WO2017018520A1 - Titanium composite material and titanium material for hot working - Google Patents
Titanium composite material and titanium material for hot working Download PDFInfo
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- WO2017018520A1 WO2017018520A1 PCT/JP2016/072342 JP2016072342W WO2017018520A1 WO 2017018520 A1 WO2017018520 A1 WO 2017018520A1 JP 2016072342 W JP2016072342 W JP 2016072342W WO 2017018520 A1 WO2017018520 A1 WO 2017018520A1
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- titanium
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- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 title claims abstract description 277
- 239000010936 titanium Substances 0.000 title claims abstract description 265
- 229910052719 titanium Inorganic materials 0.000 title claims abstract description 264
- 239000002131 composite material Substances 0.000 title claims abstract description 46
- 239000000463 material Substances 0.000 title claims description 177
- 239000002344 surface layer Substances 0.000 claims abstract description 121
- 239000010410 layer Substances 0.000 claims abstract description 105
- 229910001069 Ti alloy Inorganic materials 0.000 claims abstract description 56
- 239000000126 substance Substances 0.000 claims abstract description 38
- 239000000203 mixture Substances 0.000 claims abstract description 36
- 239000012535 impurity Substances 0.000 claims abstract description 10
- 238000005098 hot rolling Methods 0.000 claims description 76
- 238000005096 rolling process Methods 0.000 claims description 29
- 229910052750 molybdenum Inorganic materials 0.000 claims description 14
- 239000000155 melt Substances 0.000 claims description 12
- 229910052758 niobium Inorganic materials 0.000 claims description 11
- 229910052720 vanadium Inorganic materials 0.000 claims description 9
- 229910052742 iron Inorganic materials 0.000 abstract description 8
- 229910052804 chromium Inorganic materials 0.000 abstract description 4
- 229910052782 aluminium Inorganic materials 0.000 abstract description 2
- 229910052759 nickel Inorganic materials 0.000 abstract description 2
- 229910052726 zirconium Inorganic materials 0.000 abstract description 2
- 239000000956 alloy Substances 0.000 description 53
- 238000000034 method Methods 0.000 description 52
- 229910045601 alloy Inorganic materials 0.000 description 48
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- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 38
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- 238000012545 processing Methods 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- 239000000843 powder Substances 0.000 description 9
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- 229910000831 Steel Inorganic materials 0.000 description 6
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- 150000003608 titanium Chemical class 0.000 description 6
- 238000005097 cold rolling Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
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- 229910000975 Carbon steel Inorganic materials 0.000 description 4
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
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- 239000010962 carbon steel Substances 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
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- 238000012935 Averaging Methods 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910001295 No alloy Inorganic materials 0.000 description 1
- 206010040844 Skin exfoliation Diseases 0.000 description 1
- 229910000883 Ti6Al4V Inorganic materials 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
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- 150000007513 acids Chemical class 0.000 description 1
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- 238000003475 lamination Methods 0.000 description 1
- 238000004093 laser heating Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
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- 229910052708 sodium Inorganic materials 0.000 description 1
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- 125000006850 spacer group Chemical group 0.000 description 1
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- 229910052715 tantalum Inorganic materials 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 238000000304 warm extrusion Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/02—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling heavy work, e.g. ingots, slabs, blooms, or billets, in which the cross-sectional form is unimportant ; Rolling combined with forging or pressing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K15/00—Electron-beam welding or cutting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
- B23K20/04—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating by means of a rolling mill
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C14/00—Alloys based on titanium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
- C22F1/18—High-melting or refractory metals or alloys based thereon
Definitions
- the present invention relates to a titanium composite material and a titanium material for hot rolling.
- Titanium material has excellent properties such as corrosion resistance, oxidation resistance, fatigue resistance, hydrogen embrittlement resistance, and neutron blocking properties. These properties can be achieved by adding various alloying elements to titanium.
- Industrially pure titanium is mainly composed of an ⁇ phase having an hcp (dense hexagonal lattice) structure, and it is known that when a large amount of hydrogen is absorbed in the ⁇ phase, a hydride is formed and embrittles. For this reason, depending on the use environment, there is a case where an accident occurs in which hydrogen is absorbed and becomes brittle and breaks.
- Non-Patent Document 1 for example, accidents due to hydrogen absorption in a plant that handles non-oxidizing acids, or in a urea / ammonia environment or a hydrogen gas environment are reported. For this reason, a titanium alloy material excellent in hydrogen embrittlement resistance has been proposed.
- Patent Document 1 discloses a titanium alloy containing 50% by volume or more of a ⁇ phase and containing 500 to 6000 ppm of hydrogen and having a large elongation at break. Even if it contains a large amount of hydrogen, it is brittle. An example is shown that does not.
- the titanium material is usually manufactured by the method shown below.
- the raw material titanium oxide is chlorinated to titanium tetrachloride by the crawl method, and then reduced with magnesium or sodium to produce a lump-like sponge-like metal titanium (sponge titanium).
- This sponge titanium is press-molded to form a titanium consumable electrode, and a titanium ingot is manufactured by vacuum arc melting using the titanium consumable electrode as an electrode.
- an alloy element is added as necessary to produce a titanium alloy ingot.
- the titanium alloy ingot is divided, forged and rolled into a titanium slab, and the titanium slab is further subjected to hot rolling, annealing, pickling, cold rolling, and vacuum heat treatment to produce a titanium thin plate.
- titanium ingot is smashed, hydroground, dehydrogenated, powder crushed, and classified to produce titanium powder, and titanium powder is powder-rolled, sintered, and cold-rolled.
- the manufacturing method is also known.
- Patent Document 2 discloses that a titanium powder is produced directly from sponge titanium, not a titanium ingot, and a titanium thin plate is produced from the obtained titanium powder.
- Sintered compacts are manufactured by sintering pre-sintered compacts made of viscous compositions containing agents and solvents into thin sheets, and sintered compacts are manufactured by compacting the sintered compacts.
- a method is disclosed in which the fracture elongation of the sintered thin plate is 0.4% or more, the density ratio is 80% or more, and the density ratio of the sintered compacted plate is 90% or more. ing.
- Patent Document 3 discloses a composite powder obtained by adding an appropriate amount of iron powder, chromium powder or copper powder to titanium alloy powder using titanium alloy scrap or titanium alloy ingot as a raw material. After extruding the carbon steel capsule, the capsule on the surface of the obtained round bar is dissolved and removed, and further solution treatment or solution treatment and aging treatment are performed to produce a titanium alloy with excellent quality by the powder method A method is disclosed.
- Patent Document 4 discloses a method in which a titanium sponge powder is filled in a copper capsule and then subjected to warm extrusion at an extrusion ratio of 1.5 or more and an extrusion temperature of 700 ° C. or less.
- a method for producing a titanium molded body in which 20% or more of the total length of the grain boundary of the molded body is in metal contact is performed by performing outer peripheral processing excluding copper.
- a pack rolling method is known as a technique for rolling the sheet.
- the pack rolling method is a method in which a core material such as a titanium alloy having poor workability is covered with a cover material such as inexpensive carbon steel having good workability and hot rolling is performed.
- a release agent is applied to the surface of the core material, and at least two upper and lower surfaces thereof are covered with a cover material, or the four peripheral surfaces are covered with a spacer material in addition to the upper and lower surfaces, and the surroundings are welded. Assembled and hot rolled.
- a core material which is a material to be rolled, is covered with a cover material and hot rolled. Therefore, the core material surface does not directly contact a cold medium (atmosphere or roll), and the temperature drop of the core material can be suppressed, so that even a core material with poor workability can be manufactured.
- Patent Document 5 discloses a method for assembling a hermetically sealed box
- Patent Document 6 discloses a degree of vacuum of 10 ⁇ 3 torr or higher.
- Patent Document 7 discloses a method of covering the carbon steel (cover material) with an order of 10 ⁇ 2 torr.
- a method for producing a hermetic coated box by sealing by high energy density welding under the following vacuum is disclosed.
- Patent Document 8 a steel material is used as a base material and titanium or a titanium alloy is used as a mating material, and the joint surface between the base material and the mating material is evacuated and then welded and assembled.
- a method for manufacturing a titanium clad steel sheet in which an assembly slab for rolling is joined by hot rolling is disclosed.
- Patent Document 9 discloses that pure nickel, pure iron, and carbon content are 0.01 mass% or less on the surface of a base steel material containing 0.03 mass% or more of carbon. After the titanium foil material is laminated by interposing an insert material made of any one of the above-mentioned low carbon steels with a thickness of 20 ⁇ m or more, a laser beam is irradiated from either side of the lamination direction, A method of manufacturing a titanium-coated steel material by melting and joining at least the vicinity of the edge with a base steel material over the entire circumference is disclosed.
- JP-A-2015-045040 Patent Document 10
- the surface of a porous titanium raw material (sponge titanium) formed into an ingot shape is melted using an electron beam under vacuum to make the surface layer portion dense titanium.
- the titanium ingot is manufactured and hot rolled and cold rolled to form a porous portion in which the porous titanium raw material is formed into an ingot shape, and the entire surface of the porous portion composed of dense titanium.
- a method for producing a dense titanium material (titanium ingot) having a dense coating portion for coating with very little energy is exemplified.
- Patent Document 11 describes that a surface effect treatment of an engine member for an automobile is performed by thermal spraying.
- JP 2013-163840 A JP 2011-42828 A JP 2014-19945 A JP 2001-131609 A JP-A-63-207401 Japanese Patent Laid-Open No. 09-136102 JP 11-057810 A Japanese Patent Laid-Open No. 08-141754 Japanese Patent Laid-Open No. 11-170076 Japanese Patent Laying-Open No. 2015-045040 JP 62-270277 A
- Titanium processing technology edited by Japan Titanium Association, Nikkan Kogyo Shimbun, p. 214-230, issued in November 1992
- sponge titanium is press-molded to form a titanium consumable electrode, and a titanium ingot is manufactured by vacuum arc melting using the titanium consumable electrode as an electrode.
- the titanium slab was forged and rolled into a titanium slab, and the titanium slab was manufactured by hot rolling, annealing, pickling, and cold rolling.
- a process of dissolving titanium and producing a titanium ingot was always added.
- a method of producing titanium powder by powder rolling, sintering, and cold rolling is also known, but in the method of producing titanium powder from a titanium ingot, a step of dissolving titanium is also added.
- the core material covered with the cover material is slab or ingot to the last, and has undergone a melting process or is made of expensive titanium powder, and the manufacturing cost cannot be reduced.
- a dense titanium material can be manufactured with very little energy, but the surface of the titanium sponge formed into an ingot shape is dissolved, and the dense titanium surface layer portion and the internal components are the same kind of pure titanium. Or it is prescribed
- thermal spraying is a method in which a film is formed by melting a metal, ceramics, or the like and spraying it on the surface of a titanium material.
- thermal spraying is performed while shielding with an inert gas in order to avoid oxidation of the film.
- inert gases are entrained in the pores of the coating.
- Such pores containing the inert gas are not pressed by hot working or the like.
- vacuum heat treatment is generally carried out, but during this treatment, the inert gas in the pores may expand and the film may be peeled off.
- the abundance ratio (porosity) of pores generated by thermal spraying is several vol. % Or more and 10 vol. % May be exceeded.
- a titanium material having a high porosity in the film has a risk of peeling in the manufacturing process, and there is a risk that a defect such as a crack during processing may occur.
- melt resolidification process As a process for melting and resolidifying the surface layer of the slab using an electron beam. Usually, the melted and re-solidified surface layer is removed in a pickling step after hot rolling. For this reason, in the conventional melt resolidification treatment, no consideration is given to the segregation of the alloy components in the surface layer portion.
- the present inventors specify the material for hot rolling at a low price by attaching a titanium plate containing a specific alloy element to the surface of a slab made of industrial pure titanium or titanium alloy. We considered obtaining a titanium material with excellent performance.
- the content of alloying elements added to improve various properties required for titanium materials such as corrosion resistance, oxidation resistance, fatigue resistance, hydrogen embrittlement resistance, and neutron barrier properties (express target characteristics)
- the purpose is to obtain a titanium composite material and hot rolling titanium material having desired characteristics at a low cost by reducing the production amount of a specific alloying element) and suppressing the production cost of the titanium material. .
- the present invention has been made to solve the above-described problems, and the gist of the present invention is the following titanium composite material and titanium material for hot rolling.
- an inner layer made of industrial pure titanium or titanium alloy A surface layer having a chemical composition different from that of the inner layer formed on at least one rolling surface of the inner layer; An intermediate layer formed between the inner layer and the surface layer and having a different chemical composition from the inner layer;
- a titanium composite comprising: The surface layer has a thickness of 2 ⁇ m or more, and the proportion of the total thickness is 40% or less per side, The chemical composition of the surface layer part is One or more selected from Mo, V and Nb, the Mo equivalent calculated by the following formula (1) is more than 8.0 and less than 20.0, the balance being titanium and impurities, The intermediate layer has a thickness of 0.5 ⁇ m or more. Titanium composite material.
- Mo equivalent Mo content (% by mass) + V content (% by mass) /1.5+Nb content (% by mass) /3.6 (1)
- Another surface layer is formed on a surface other than the rolled surface of the inner layer,
- the other surface layer has the same chemical composition as the surface layer,
- a base material made of pure industrial titanium or a titanium alloy; A surface layer material joined to at least one rolling surface of the base material; A titanium material for hot rolling comprising a welded portion that joins the periphery of the base material and the surface layer material, The surface layer material has a different chemical composition from the base material, and One or more selected from Mo, V and Nb, the Mo equivalent calculated by the following formula (1) is more than 8.0 and less than 20.0, the balance being titanium and impurities, The welded portion shields the interface between the base material and the surface material from outside air; Titanium material for hot rolling.
- Mo equivalent Mo content (% by mass) + V content (% by mass) /1.5+Nb content (% by mass) /3.6 (1)
- the base material comprises a direct cast slab.
- the directly cast slab is obtained by forming a melt-resolidified layer on at least a part of the surface.
- the chemical composition of the melt-resolidified layer is different from the chemical composition of the center portion of the thickness of the direct cast slab, (6) Titanium material for hot rolling.
- the titanium composite material according to the present invention includes an inner layer made of industrial pure titanium or a titanium alloy and a surface layer having a chemical composition different from that of the inner layer, the whole is compared with a titanium material made of the same titanium alloy. Thus, it has the same characteristics but can be manufactured at low cost.
- FIG. 1 is an explanatory view showing an example of the configuration of a titanium composite material according to the present invention.
- FIG. 2 is an explanatory view showing an example of the configuration of the titanium composite material according to the present invention.
- FIG. 3 is an explanatory view schematically showing that the titanium rectangular slab and the titanium plate are bonded together by welding in a vacuum.
- FIG. 4 is an explanatory view schematically showing bonding by welding a titanium plate not only on the surface of the titanium rectangular cast piece but also on the side surface.
- FIG. 5 is an explanatory view showing a method of melt re-solidification.
- FIG. 6 is an explanatory view showing a method of melt re-solidification.
- FIG. 7 is an explanatory view showing a method of melt re-solidification.
- the present inventors reduced the amount of a specific alloy element that expresses a target characteristic by alloying only the surface layer of the titanium plate of the final product, and As a result of diligent investigations to reduce the manufacturing cost, the interface between the base material made of industrial pure titanium or titanium alloy and the surface layer material having a chemical composition different from the base material is shielded from the outside air.
- the titanium material for hot rolling which welded the circumference
- the titanium composite material obtained by hot working the titanium material for hot rolling becomes a titanium material having excellent properties at low cost.
- Titanium composite 1-1 The surface layers 3 and 4 which have a composition, and the intermediate
- a surface layer is formed on one or both rolling surfaces of the inner layer 5, but a surface other than the rolling surface of the inner layer 5 (side surface in the example shown in FIGS. 1 and 2).
- the surface layer, the inner layer, and the intermediate layer will be sequentially described.
- the thickness is 2 ⁇ m or more, and the proportion of the total thickness is 40% or less per side.
- the thickness of the surface layer is preferably 5 ⁇ m or more, and more preferably 10 ⁇ m or more.
- the ratio of the thickness of the surface layer to the total thickness of the titanium composite is 40% or less per side, more preferably 30% or less, and particularly preferably 2 to 20%.
- the layer for obtaining hydrogen absorption resistance is a titanium alloy layer containing a certain range of ⁇ -stabilizing elements.
- the reason for prescribing the formation of the ⁇ phase is that the ⁇ phase of titanium forms a hydride even at a hydrogen concentration of only a few tens of ppm, whereas the ⁇ phase of the titanium alloy can dissolve about 1000 ppm or more of hydrogen, This is because it has the characteristic that it is difficult to cause embrittlement due to hydrogen.
- ⁇ -stabilizing element such as Fe or Cr
- titanium and these elements form a compound and cause embrittlement.
- ⁇ -stabilizing elements when Mo, V, and Nb are contained in a range that satisfies “8.0 ⁇ Mo equivalent ⁇ 20.0”, the ⁇ -phase may be present even if Fe and Cr are present at the same time. Is stable and does not form a compound phase, and thus does not cause embrittlement.
- the lower limit of the Mo equivalent is the amount of alloy necessary to obtain a sufficient amount of ⁇ phase.
- the upper limit was determined because a titanium alloy with a large amount of alloy addition is not suitable for use because of its high cost.
- the existing ⁇ -type titanium alloy can be used for forming the surface alloy layer.
- inclusion of additive elements such as Cr, Sn, Al, and Zr other than the above elements is allowed if the total amount is 15% or less. This is because these elements are elements included for adjusting heat treatment property, strength, and cold workability in the existing ⁇ -type titanium alloy, and do not lower the Mo equivalent defined in the present invention.
- Si, Fe and the like may be further contained.
- Impurities can be contained within a range that does not hinder the target characteristics, and other impurities include Ta, Si, Mn, and Cu as impurity elements mainly mixed from scrap, and C, which are general impurity elements, In combination with N, Fe, O and H, a total amount of 5% or less is allowed.
- Inner layer 5 is made of industrial pure titanium or a titanium alloy.
- industrial pure titanium is used for the inner layer 5
- the processability at room temperature is excellent as compared with a titanium material made entirely of the same titanium alloy.
- the industrial pure titanium mentioned here is an industry defined by JIS standards 1 to 4 and ASTM standards Grades 1 to 4 and DIN standards 3, 7025, 3, 7035, and 37055. Contains pure titanium. That is, the industrial pure titanium targeted in the present invention is, for example, C: 0.1% or less, H: 0.015% or less, O: 0.4% or less, N: 0.07% or less, Fe: It consists of 0.5% or less and the balance Ti.
- a titanium alloy may be used for the inner layer 5.
- the alloy cost can be significantly reduced and high strength can be obtained.
- any of an ⁇ -type titanium alloy, an ⁇ + ⁇ -type titanium alloy, and a ⁇ -type titanium alloy can be used according to a required application.
- the ⁇ -type titanium alloy for example, a high corrosion resistance alloy (ASTM Grade 7, 11, 16, 26, 13, 30, 33, or a titanium material containing a small amount of JIS species corresponding thereto and various elements).
- Examples of ⁇ + ⁇ type titanium alloys include Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-6Al-7V, Ti-3Al-5V, Ti-5Al-2Sn-2Zr-4Mo-4Cr, Ti-6Al. -2Sn-4Zr-6Mo, Ti-1Fe-0.35O, Ti-1.5Fe-0.5O, Ti-5Al-1Fe, Ti-5Al-1Fe-0.3Si, Ti-5Al-2Fe, Ti-5Al -2Fe-0.3Si, Ti-5Al-2Fe-3Mo, Ti-4.5Al-2Fe-2V-3Mo, or the like can be used.
- ⁇ -type titanium alloy for example, Ti-11.5Mo-6Zr-4.5Sn, Ti-8V-3Al-6Cr-4Mo-4Zr, Ti-10V-2Fe-3Mo, Ti-13V-11Cr-3Al Ti-15V-3Al-3Cr-3Sn, Ti-6.8Mo-4.5Fe-1.5Al, Ti-20V-4Al-1Sn, Ti-22V-4Al, and the like can be used.
- the titanium and titanium alloy used for the inner layer 5 desirably have a 0.2% proof stress of 1000 MPa or less.
- the titanium composite material of the present invention includes an intermediate layer between the inner layer and the surface layer. That is, a titanium material for hot rolling, which will be described later, is a material in which a surface layer material is attached to a base material and the periphery thereof is welded. During the subsequent hot rolling and heat treatment processes after cold rolling, the base material and the surface layer When diffusion occurs at the interface with the material and the titanium composite material is finally finished, an intermediate layer is formed between the inner layer derived from the base material and the surface layer derived from the surface material. This intermediate layer has a chemical composition different from the chemical composition of the base material. This intermediate layer bonds the inner layer and the surface layer to each other and bonds them firmly. Further, since a continuous element gradient is generated in the intermediate layer, the difference in strength between the inner layer and the surface layer can be reduced, and cracks during processing can be suppressed.
- the thickness of the intermediate layer can be measured using EPMA or GDS. If GDS is used, more detailed measurement is possible. In the case of GDS, after removing the surface layer to some extent by polishing, the thickness of the intermediate layer can be measured by performing GDS analysis in the depth direction from the surface.
- the intermediate layer is the increased content from the base material (in the case of an element not included in the base material, its content, in the case of an element also included in the base material, the increase in content from the base material) ) Is C MID, and the average of the increased content in the surface layer portion is C AVE , it means a region of 0 ⁇ C MID ⁇ 0.8 ⁇ C AVE .
- the thickness of this intermediate layer is 0.5 ⁇ m or more. On the other hand, if the thickness of the intermediate layer becomes too large, the surface alloy layer may become thin by that amount, and the effect may not be exhibited. Therefore, the upper limit is preferably 15 ⁇ m.
- Titanium material for hot rolling is a material (slab of slab, bloom, billet, etc.) used for hot working, and after hot working, it can be cooled if necessary. It is processed into a titanium composite material by performing inter-processing, heat treatment, etc.
- the titanium material for hot rolling according to the present invention will be described with reference to the drawings.
- “%” regarding the content of each element means “mass%”.
- FIG. 3 is an explanatory view schematically showing that the base material (titanium rectangular cast, slab) 6 and the surface layer material (titanium plate) 7 are bonded together in a vacuum, and FIG. It is typical to bond the surface materials (titanium plates) 7 and 8 not only to the surface (rolled surface) of the base material (titanium rectangular cast slab, slab) but also to the side surfaces (surfaces other than the rolled surface). It is explanatory drawing shown in.
- titanium plates 7 and 8 containing alloy elements that exhibit characteristics are bonded to the surface of a slab 6 that is a base material, and then bonded by hot rolling cladding.
- the surface layers of the titanium composite materials 1 and 2 are alloyed.
- a titanium plate 7 may be bonded to only one side of the slab 6 in a vacuum as shown in FIG. 3, and the titanium plate 7 is attached to the other side of the slab 6. You may hot-roll without sticking.
- a titanium plate 7 may be bonded to one side of the slab 6 as well as the other side. Thereby, generation
- a plate containing an alloy element may be bonded to both rolling surfaces of the slab 6 as shown in FIG.
- the same standard titanium plate 8 may be bonded together in a vacuum and welded to the side surface of the slab 6 that becomes the edge side during hot rolling.
- the amount of the side surface of the slab 6 that wraps around during hot rolling varies depending on the manufacturing method, but is usually about 20 to 30 mm. Therefore, it is not necessary to attach the titanium plate 8 to the entire side surface of the slab 6, and the manufacturing method is not limited. It is only necessary to attach the titanium plate 8 only to the portion corresponding to the sneak amount.
- titanium composites 1 and 2 are manufactured, they are manufactured through a shot-pickling process after hot rolling in order to remove the oxide layer formed by hot rolling. However, if the surface layer formed by the hot-rolled cladding is removed during this step, desired characteristics cannot be expressed.
- the thickness of the surface layer of the titanium composites 1 and 2 becomes too thin, the desired desired characteristics will not be exhibited. On the other hand, if the thickness of the surface layer is too thick, the manufacturing cost increases accordingly. Since the titanium composite materials 1 and 2 only have to have a surface layer thickness suitable for the purpose of use, the thickness of the titanium plates 7 and 8 used as the material is not particularly limited, but the thickness of the slab 6 It is preferably in the range of 5 to 40%.
- titanium plate As the surface layer material (titanium plate), a titanium plate having the predetermined chemical composition described in the section of the surface layer of the titanium composite material is used. In particular, it is desirable to adjust the chemical composition of the titanium plate to a component containing a predetermined element in the same component as the base material in order to suppress the plate breakage during hot rolling. .
- Base material As the base material, the industrial pure titanium or titanium alloy described in the section of the inner layer of the titanium composite is used. In particular, it is preferable to use a direct casting slab as a base material.
- the direct cast slab may be one in which a melt resolidified layer is formed on at least a part of the surface.
- a predetermined element was added to the surface of the direct casting slab when the melt resolidification process was performed, and a melt resolidification layer having a chemical composition different from that of the center portion of the direct casting slab was formed. May be.
- the slab 6 and the titanium plates 7 and 8 are welded at least around the welded portion 9 in a vacuum vessel.
- the slab 6 and the titanium plates 7 and 8 are bonded together by sealing with a vacuum, blocking the outside air, and rolling.
- the welded portion to be joined after the titanium plates 7 and 8 are bonded to the slab 6 is shielded from the atmosphere at the interface between the slab 6 and the titanium plates 7 and 8. Weld.
- Titanium is an active metal and forms a strong passive film on the surface when left in the atmosphere. It is impossible to remove the oxidized layer on the surface. However, unlike stainless steel, etc., oxygen easily dissolves in titanium. Therefore, when heated in a vacuum and sealed without external oxygen supply, oxygen on the surface diffuses into the solid solution. Therefore, the passive film formed on the surface disappears. Therefore, the slab 6 and the titanium plates 7 and 8 on the surface thereof can be completely adhered by the hot rolling cladding method without generating any inclusions between them.
- the slab 6 when an as-cast slab is used as the slab 6, surface defects occur in the subsequent hot rolling process due to coarse crystal grains generated during solidification.
- the titanium plates 7 and 8 are bonded to the rolled surface of the slab 6 as in the present invention, the bonded titanium plate 7 has a fine structure, so that surface defects in the hot rolling process can be suppressed. .
- a base material of a titanium material for hot rolling is usually manufactured by cutting and refining an ingot after making it into a slab or billet shape by breakdown. In recent years, rectangular slabs that can be hot-rolled directly at the time of ingot production are sometimes produced and used for hot-rolling. When manufactured by breakdown, since the surface is relatively flat by breakdown, it is easy to disperse the material containing the alloy element relatively uniformly, and it is easy to make the element distribution of the alloy phase uniform.
- an ingot directly manufactured in the shape of a hot-rolling material during casting (direct casting slab)
- the cutting and refining process can be omitted, so that it can be manufactured at a lower cost.
- the ingot is manufactured and then used after the surface is cut and refined, the same effect can be expected when it is manufactured through breakdown.
- an alloy layer may be stably formed on the surface layer, and an appropriate material may be selected according to the situation.
- the slab and welding the surroundings After assembling the slab and welding the surroundings, it is heated to 700 to 850 ° C. and subjected to 10-30% joint rolling, and then heated at the ⁇ -zone temperature for 3 to 10 hours to diffuse the base material components to the surface layer. It is preferable to perform hot rolling later. This is because by performing hot rolling at a ⁇ -region temperature, the deformation resistance becomes low and rolling becomes easy.
- the direct cast slab used as the base material may be one in which a melt resolidification layer is formed on at least a part of the surface.
- a predetermined element was added to the surface of the direct casting slab when the melt resolidification process was performed, and a melt resolidification layer having a chemical composition different from that of the center portion of the direct casting slab was formed. May be.
- the melt resolidification process will be described in detail.
- FIGS. 5 to 7 are explanatory diagrams showing the method of melt re-solidification.
- a method for melting and resolidifying the surface of the base material of the titanium material for hot rolling there are laser heating, plasma heating, induction heating, electron beam heating, etc., and any method may be used.
- electron beam heating since it is performed in a high vacuum, even if a void or the like is formed in this layer during the melt resolidification treatment, it can be made harmless by pressure bonding in subsequent rolling because it is a vacuum.
- the degree of vacuum in the case of melting in a vacuum is desirably higher than 3 ⁇ 10 ⁇ 3 Torr.
- the processing time becomes longer and the cost increases.
- the melt resolidification method of the surface layer is carried out as shown in FIG. 5 in the case of a rectangular slab. That is, among the outer surfaces of the rectangular slab 10, at least two wide surfaces 10A and 10B that become the rolling surfaces (surfaces in contact with the hot rolling roll) in the hot rolling process are irradiated with an electron beam, and the surfaces on the surfaces are irradiated. Only melt the layer.
- the surface 10A is one of the two surfaces 10A and 10B.
- the area of the electron beam irradiation region 14 by the single electron beam irradiation gun 12 on the surface 10A of the rectangular slab 10 is compared with the total area of the surface 10A to be irradiated.
- the electron beam irradiation is actually performed while continuously moving the electron beam irradiation gun 12 or continuously moving the rectangular slab 10. It is normal.
- the shape and area of this irradiation area can be adjusted by adjusting the focus of the electron beam or by using an electromagnetic lens to oscillate a small beam at a high frequency (oscillation Oscillation) to form a beam bundle. can do.
- the moving direction of the electron beam irradiation gun is not particularly limited, it is generally continuous along the length direction (usually the casting direction D) or the width direction (usually the direction perpendicular to the casting direction D) of the rectangular slab 10.
- the irradiation region 14 is continuously irradiated in a band shape with a width W (in the case of a circular beam or beam bundle, a diameter W).
- the electron beam irradiation is performed in a belt shape while continuously moving the irradiation gun 12 in the reverse direction (or the same direction) in the adjacent unirradiated belt region.
- a plurality of irradiation guns may be used to simultaneously perform electron beam irradiation on a plurality of regions.
- FIG. 5 the case where a rectangular beam is continuously moved along the length direction (usually casting direction D) of the rectangular slab 10 is shown.
- the surface (surface 10A) of the rectangular titanium cast piece 10 is irradiated with an electron beam by such a surface heat treatment step and heated to melt the surface, the rectangular titanium as shown in the left side of the center of FIG.
- the surface layer of the surface 10A of the slab 10 is melted at the maximum by a depth corresponding to the heat input.
- the depth from the direction perpendicular to the irradiation direction of the electron beam is not constant as shown in FIG. 7, and the depth becomes the largest at the central part of the electron beam irradiation, and the thickness increases toward the strip-shaped end part. Decreases, resulting in a downwardly convex curved shape.
- the surface layer is melted and re-solidified with a material composed of the target alloy element, whereby the surface layer of the material for hot rolling can be alloyed to form an alloy layer having a chemical composition different from that of the base material.
- a material used in this case one or more of powder, chip, wire, thin film, cutting powder, and mesh may be used.
- the component and amount of the material to be arranged before melting are determined so that the component in the element concentration region after melting and solidifying together with the material surface becomes the target component.
- the melt resolidification treatment After the melt resolidification treatment, it is preferable to hold at a temperature of 100 ° C. or higher and lower than 500 ° C. for 1 hour or longer. If it is cooled rapidly after melting and resolidification, fine cracks may occur in the surface layer due to strain during solidification. In the subsequent hot rolling process and cold rolling process, the fine cracks may be the starting point, and the surface layer may be peeled off, or the part of the alloy layer may be partially thin. Further, if the inside is oxidized due to fine cracks, it is necessary to remove in the pickling process, and the thickness of the alloy layer is further reduced. By maintaining at the above temperature, fine cracks on the surface can be suppressed. At this temperature, atmospheric oxidation hardly occurs even if the temperature is maintained.
- a titanium material for hot rolling can be manufactured by attaching a titanium plate containing a predetermined alloy component to the surface of a base material provided with a surface layer portion formed by melt resolidification treatment.
- the titanium material for hot rolling is preferably bonded to the slab 6 and the titanium plates 7 and 8 which are welded in advance by the hot rolled clad method.
- the titanium plates 7 and 8 containing alloy elements that express characteristics are bonded to the surface layer of the slab 6, and then bonded by hot rolling cladding to alloy the surface layer of the titanium composite material.
- the slab 6 and the titanium plate 7 are preferably welded at least around the welded portion 9 in a vacuum vessel.
- the space between the slab 6 and the titanium plate 7 is bonded together by vacuum sealing and rolling.
- the entire circumference is welded so that air does not enter between the slab 6 and the titanium plate 7.
- Titanium is an active metal and forms a strong passive film on the surface when left in the atmosphere. It is impossible to remove the oxidized layer on the surface. However, unlike stainless steel, etc., oxygen easily dissolves in titanium. Therefore, when heated in a vacuum and sealed without external oxygen supply, oxygen on the surface diffuses into the solid solution. Therefore, the passive film formed on the surface disappears. For this reason, the slab 6 and the titanium plate 7 on the surface thereof can be completely adhered by the hot rolling cladding method without generating any inclusions between them.
- the slab 6 when an as-cast slab is used as the slab 6, surface defects occur in the subsequent hot rolling process due to coarse crystal grains generated during solidification.
- the titanium plate 7 when the titanium plate 7 is bonded to the rolled surface of the slab 6 as in the present invention, the bonded titanium plate 7 has a fine structure, so that surface defects in the hot rolling process can be suppressed.
- titanium plates 7 may be bonded to both sides of the slab 6 instead of just one side. Thereby, generation
- hot rolling at least a part of the side surface of the slab 6 usually wraps around the surface side of the hot-rolled sheet by being rolled down by the slab 6. Therefore, if the structure of the surface layer on the side surface of the slab 6 is coarse or a large number of defects exist, surface flaws may occur on the surface near both ends in the width direction of the hot-rolled sheet.
- the same standard titanium plate 8 is preferably bonded and welded to the side surface of the slab 6 on the edge side during hot rolling as well as the rolled surface. Thereby, generation
- This welding is preferably performed in a vacuum.
- the amount of the side surface of the slab 6 that wraps around during hot rolling varies depending on the manufacturing method, but is usually about 20 to 30 mm. Therefore, it is not necessary to attach the titanium plate 8 to the entire side surface of the slab 6, and the manufacturing method is not limited. It is only necessary to attach the titanium plate 8 only to the portion corresponding to the sneak amount.
- the base material-derived component can be contained in the titanium composite material. For example, heat treatment at 700 to 900 ° C. for 30 hours is exemplified.
- Methods for welding the slab 6 and the titanium plates 7 and 8 in vacuum include electron beam welding and plasma welding.
- the electron beam welding can be performed under a high vacuum
- the space between the slab 6 and the titanium plates 7 and 8 can be made a high vacuum, which is desirable.
- the degree of vacuum when the titanium plates 7 and 8 are welded in a vacuum is desirably a higher degree of vacuum of 3 ⁇ 10 ⁇ 3 Torr or less.
- the slab 6 and the titanium plate 7 are not necessarily welded in a vacuum vessel.
- a vacuum suction hole is provided in the titanium plate 7 and the titanium plate 7 is overlapped with the slab 6. Later, the slab 6 and the titanium plate 7 may be welded while evacuating the slab 6 and the titanium plate 7 using a vacuum suction hole, and the vacuum suction hole may be sealed after welding.
- the thickness and chemical composition of the surface layer are as follows: It depends on the thickness of the titanium plates 7 and 8 before bonding and the distribution of alloy elements.
- the annealing treatment is performed in a vacuum atmosphere or the like in order to obtain the finally required strength and ductility.
- a concentration gradient is generated in the depth direction.
- the diffusion distance of the element generated in the final annealing step is about several ⁇ m, and the entire thickness of the alloy layer does not diffuse, and does not affect the concentration of the alloy element in the vicinity of the surface layer, which is particularly important for property development.
- titanium plates 7 and 8 the uniformity of the alloy components in the entire titanium plates 7 and 8 leads to stable expression of the characteristics.
- titanium plates 7 and 8 manufactured as products it is possible to use titanium plates 7 and 8 manufactured as products, so it is easy to control the segregation of alloy components as well as the plate thickness accuracy, and have a uniform thickness and chemical properties after manufacturing. Titanium composite materials 1 and 2 having a surface layer having components can be produced, and stable characteristics can be expressed.
- Hot rolling process Also in the hot rolling process, if the surface temperature is too high, a large amount of scale is generated during sheet passing, and the scale loss increases. On the other hand, if it is too low, the scale loss is reduced, but surface flaws are likely to occur. Therefore, it is necessary to remove by surface pickling, and it is desirable to perform hot rolling in a temperature range in which surface flaws can be suppressed. . Therefore, it is desirable to perform rolling in the optimum temperature range. In addition, since the surface temperature of the titanium material decreases during rolling, it is desirable to minimize roll cooling during rolling and suppress the decrease in the surface temperature of the titanium material.
- the hot-rolled plate has an oxide layer on its surface
- the oxide layer is generally removed by pickling with a nitric hydrofluoric acid solution.
- the surface may be ground by grinding with a grindstone after pickling.
- a two-layer or three-layer structure including an inner layer and a surface layer derived from the base material and the surface layer portion of the titanium material for hot rolling may be used.
- a shot blast treatment is performed as a pretreatment for the pickling treatment to remove a part of the scale on the surface, and at the same time, cracks are formed on the surface, and in the subsequent pickling step The liquid penetrates into the cracks and removes part of the base material.
- a titanium alloy plate with a thickness of 3 mm is attached to the upper and lower surfaces of a slab made of two types of industrial pure titanium JIS with a thickness of 60 mm, a width of 100 mm, and a length of 120 mm by electron beam welding in a vacuum atmosphere of 3 ⁇ 10 ⁇ 3 Torr or less. Combined. Thereafter, it was heated to 850 ° C. and hot rolled to a plate thickness of 4.8 to 5.0 mm. Next, annealing was performed in a vacuum atmosphere at 600 to 650 ° C. for 4 to 10 hours. Furthermore, shot blasting and pickling were performed to remove the scale layer.
- the titanium composite plate 2 shown in FIG. 2 in which the surface layers 3 and 4 are made of a Ti alloy and the inside 5 is made of industrial pure titanium JIS type 2 by the above-described hot-rolled cladding was used.
- an industrial pure titanium JIS type 2 material having no surface layers 3 and 4 was used. Both plate thicknesses are 4.8-5 mm.
- the titanium composite plate 2 of the present invention example and the titanium plate of the comparative example were exposed at 400 to 500 ° C. for 5 hours in a 1% by volume H 2 + 99% Ar atmosphere as a hydrogen absorption environment.
- an impact test piece of 4.8 to 5 mm ⁇ 10 mm ⁇ 55 mm and 2 mm V notch was produced with the notch direction as the plate thickness penetration direction. Then, an impact value was calculated by dividing the impact absorption energy measured in the Charpy impact test by the cross-sectional area of the test piece fracture portion, and the hydrogen embrittlement characteristics were evaluated based on the value.
- the manufactured titanium composite plate was embedded in a resin so that the cross section could be observed, polished and corroded, and then observed with an optical microscope to measure the thickness of the surface layer.
- the measured thickness of the surface layer was divided by the total thickness of the titanium composite material to calculate the surface layer occupation rate.
- the surface layer occupation ratio in this example was in the range of 3 to 5%.
- Table 1 shows the exposure conditions, hydrogen concentration, and impact absorption energy for ordinary industrial pure titanium having no surface layers 3 and 4.
- the impact value obtained by dividing the impact absorption energy by the cross-sectional area of the specimen decreased to less than 2.0 ⁇ 10 2 J / cm 2 .
- the hydrogen concentration is sufficiently low, it is 2.7 ⁇ 10 2 J / cm 2, which is a decrease of 20% or more.
- the test results are summarized in Table 2.
- the element concentration in the surface layer portion in Table 2 is a result of performing line analysis using EPMA and averaging the range from the surface to the lower end of the alloy layer.
- the exposure conditions under a hydrogen environment are all 500 ° C. for 5 hours. It corresponds to 3.
- the Ti alloys of the surface layers 3 and 4 contain Mo alone. In Nos. 6 to 9, Ti alloys of the surface layers 3 and 4 contain V alone. In Nos. 10 to 15, the Ti alloys of the surface layers 3 and 4 contain a combination of two or more of Mo, V and Nb.
- the present invention is No.
- the impact values of 2 to 4 and 7 to 14 are as high as 2.4 to 2.8 ⁇ 10 2 J / cm 2 , indicating that they have excellent hydrogen embrittlement resistance.
- No. which is a comparative example. 1 has an impact value as small as 1.4 J ⁇ 10 2 / cm 2 because the Mo equivalent is as low as 4.
- No. which is a comparative example. 5 has a high Mo equivalent of 22, and an impact value as small as 1.8 J ⁇ 10 2 / cm 2 .
- No. which is a comparative example. 6 has a low Mo equivalent of 6.7 and an impact value as small as 1.8 J ⁇ 10 2 / cm 2 .
- No. 15 has a low Mo equivalent of 5.8 and an impact value as small as 1.7 J ⁇ 10 2 / cm 2 .
- the titanium composite plate 2 according to the present invention has extremely excellent hydrogen embrittlement resistance as compared with the titanium plate of the comparative example.
- Thickness 60 mm, width 100 mm, the upper and lower surfaces of the titanium slab made of commercially pure titanium two lengths 120 mm, the titanium alloy Ti-15V-3Cr-3Sn- 3Al sheet having a thickness of 1 ⁇ 25mm, 3 ⁇ 10 - Bonding was performed by electron beam welding in a vacuum atmosphere of 3 Torr or less. Thereafter, it was heated to 850 ° C. and hot rolled to a plate thickness of 4.8 to 5.0 mm. Next, annealing was performed in a vacuum atmosphere at 600 to 650 ° C. for 4 to 10 hours. Furthermore, shot blasting and pickling were performed to remove the scale layer.
- Example 2 Thereafter, as in Example 1, after exposure at 400 to 500 ° C. for 5 hours in a 1% by volume H 2 + 99% Ar atmosphere, which is a hydrogen absorption environment, a Charpy impact test piece was collected, the impact value was calculated, and hydrogen embrittlement was calculated. The crystallization properties were evaluated.
- a titanium alloy Ti-15V-3Cr-3Sn-3Al plate having a thickness of 5 mm is formed on the upper and lower surfaces of a titanium slab made of a titanium alloy Ti-1Fe-0.35O having a thickness of 60 mm, a width of 100 mm, and a length of 120 mm.
- a titanium slab made of a titanium alloy Ti-1Fe-0.35O having a thickness of 60 mm, a width of 100 mm, and a length of 120 mm.
- Were bonded together by electron beam welding in a vacuum atmosphere of 3 ⁇ 10 ⁇ 3 Torr or less. Thereafter, it was heated to 850 ° C. and hot-rolled to a thickness of 4.8 to 5.0 mm.
- annealing was performed in a vacuum atmosphere at 600 to 650 ° C. for 4 to 10 hours. Furthermore, shot blasting and pickling were performed to remove the scale layer.
- the impact value of the Ti-1Fe-0.35O alloy not having the surface layers 3 and 4 when not exposed to a hydrogen environment was 0.38 ⁇ 10 2 J / cm 2 .
- No. which is a comparative example. 1 is a case where the surface layers 3 and 4 are not provided, and the impact value is as low as 0.25 ⁇ 10 2 J / cm 2 .
- the slab which is the base material for producing the titanium composite material 2 having the surface layers 3 and 4 containing a predetermined alloy, is cut by hot forging an industrial pure titanium ingot produced by vacuum arc melting.
- the produced 124 mm-thick slab was used.
- the chemical composition of the titanium ingot in this example is in the range of O: 0.030 to 0.090% and Fe: 0.020 to 0.060%.
- a pure molybdenum plate with a thickness of 1 mm is placed on the slab surface, the slab surface is melted to a depth of 3 to 15 mm together with the molybdenum plate by electron beam heating, and a region where the solid solution of Mo is dissolved to a depth of 3 to 15 mm is formed on the entire surface of the slab. It was.
- the slab was heated to 850 ° C. and hot-rolled to a thickness of 5 mm, and then descaling was performed on both the front and back surfaces using shot blasting and nitric hydrofluoric acid. Heat treatment was performed in a vacuum or an inert gas atmosphere to 600 to 700 ° C. and held for 240 minutes.
- a hot rolling, descaling and heat treatment steps were similarly performed using a titanium slab having no surface layers 3 and 4 to produce a comparative example.
- Each titanium plate produced above was exposed at 500 ° C. for 5 hours in a 1% by volume H 2 + 99% by volume Ar atmosphere as a hydrogen absorption environment.
- an impact test piece having a thickness (4.8 to 5.0 mm) ⁇ 10 mm ⁇ 55 mm and 2 mmV notch was prepared.
- the longitudinal direction of the test piece was the rolling direction, and the notch direction was the plate thickness penetration direction. Hydrogen brittleness was evaluated by impact value.
- the alloy element concentrations of the surface layers 3 and 4 are average values as a result of performing a line analysis on the range from the surface to the lower end of the alloy concentrated portion using EPMA.
- the remainder is a component contained in industrial pure titanium except for contamination components such as O and C. The results are summarized in Table 5.
- Nos. 3 to 5 have Mo equivalents of the surface layers 3 and 4 of 8.3 to 17% and a ratio of the alloy layer thickness to the plate thickness of 8.1 to 19%, satisfying the scope of the present invention and having an impact value of 2. 4 to 2.6 ⁇ 10 2 J / cm 2 and 2.0 J / cm 2 or more.
- Mo, V, Nb powder is sprinkled on the slab surface, the slab surface is melted to a depth of 2 to 8 mm together with the alloy powder by electron beam heating, and a depth of 2 to 8 mm is obtained on the entire surface of the slab layer where the alloy elements are dissolved. Formed.
- the slab was heated to 850 ° C. and hot-rolled to a thickness of 5 mm, and then descaling treatment was performed on both the front and back surfaces using shot blasting and nitric hydrofluoric acid. Heat treatment was performed in a vacuum or an inert gas atmosphere to 600 to 700 ° C. and held for 240 minutes.
- Each titanium plate produced above was exposed at 500 ° C. for 5 hours in a 1% by volume H 2 + 99% by volume Ar atmosphere as a hydrogen absorption environment.
- the alloy element concentration of the surface layers 3 and 4 is an average value as a result of performing a line analysis on the range from the surface to the alloy concentrated portion using EPMA.
- the remainder is a component contained in industrial pure titanium except for contamination components such as O and C.
- the exposure conditions under a hydrogen environment are all 500 ° C. and 5 hours. It corresponds to 3.
- the results are summarized in Table 6.
- Each of Nos. 1 to 7 has a surface layer occupation ratio (ratio of the thickness of the alloy layer to the total thickness) of 3 to 5%, which satisfies the scope of the present invention.
- No. which is an example of the present invention. 1 includes Mo and V of 11.3 in Mo equivalent, and the impact value is 2.0 ⁇ 10 2 J / cm 2 or more.
- No. which is an example of the present invention. 3 includes Mo, 11.2 Mo, V, and Nb in terms of Mo equivalent, and the impact value is 2.0 ⁇ 10 2 J / cm 2 or more.
- No. which is an example of the present invention. 4 includes 10.0 V in Mo equivalent and an impact value of 2.0 ⁇ 10 2 J / cm 2 or more.
- 6 contains Mo and Nb of 14.0 in terms of Mo, and the impact value is 2.0 ⁇ 10 2 J / cm 2 or more.
- No. which is a comparative example. 7 contained only 4.0 Mo in terms of Mo, and the impact value was less than 2.0 ⁇ 10 2 J / cm 2 .
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Abstract
A titanium composite material 1 is provided with: an inner layer 5 comprising industrial pure titanium or a titanium alloy; a surface layer 3 that is formed on at least one surface of the inner layer 5 and that has a different chemical composition than the inner layer 5; and an intermediate layer that is formed between the inner layer 5 and the surface layer 3 and that has a different chemical composition than the inner layer 5. The surface layer 3 has a thickness of 2 µm or more and the proportion of the total thickness of the titanium composite material occupied by one surface of said surface layer 3 is 40% or less. The thickness of the intermediate layer is 0.5 µm or more. The chemical composition of the surface layer 3 includes: 0.08-1.0% of one or more substances selected from among Fe, Cr, Ni, Al, and Zr; and a remainder of titanium and impurities. The titanium composite material has the desired properties despite being inexpensive.
Description
本発明は、チタン複合材および熱間圧延用チタン材に関する。
The present invention relates to a titanium composite material and a titanium material for hot rolling.
チタン材は、耐食性、耐酸化性、耐疲労性、耐水素脆化性、中性子遮断性などの特性に優れている。これらの特性は、チタンに様々な合金元素を添加することにより達成することができる。
Titanium material has excellent properties such as corrosion resistance, oxidation resistance, fatigue resistance, hydrogen embrittlement resistance, and neutron blocking properties. These properties can be achieved by adding various alloying elements to titanium.
工業用純チタンはｈｃｐ（稠密六方格子）構造のα相を主体としており、α相に水素を多量に吸収すると水素化物を形成して脆化することが知られている。このため使用環境によっては、水素を吸収して脆化し、破断する事故が起きる場合がある。「チタンの加工技術」（非特許文献１）では、例えば、非酸化性の酸を扱うプラント、または、尿素・アンモニア環境、水素ガス環境での、水素吸収による事故が報告されている。このため、耐水素脆化性に優れるチタン合金材が提案されている。
Industrially pure titanium is mainly composed of an α phase having an hcp (dense hexagonal lattice) structure, and it is known that when a large amount of hydrogen is absorbed in the α phase, a hydride is formed and embrittles. For this reason, depending on the use environment, there is a case where an accident occurs in which hydrogen is absorbed and becomes brittle and breaks. In “Titanium processing technology” (Non-Patent Document 1), for example, accidents due to hydrogen absorption in a plant that handles non-oxidizing acids, or in a urea / ammonia environment or a hydrogen gas environment are reported. For this reason, a titanium alloy material excellent in hydrogen embrittlement resistance has been proposed.
特開２０１３－１６３８４０号公報（特許文献１）には、５０体積％以上のβ相を含み、水素を５００～６０００ｐｐｍ含む破断伸びが大きいチタン合金が開示されており、水素を多量に含んでも脆化しない例が示されている。
Japanese Unexamined Patent Publication No. 2013-163840 (Patent Document 1) discloses a titanium alloy containing 50% by volume or more of a β phase and containing 500 to 6000 ppm of hydrogen and having a large elongation at break. Even if it contains a large amount of hydrogen, it is brittle. An example is shown that does not.
チタン材は、通常、以下に示す方法により製造される。まず、クロール法によって、原料である酸化チタンを塩素化して四塩化チタンとした後、マグネシウムまたはナトリウムで還元することにより、塊状でスポンジ状の金属チタン（スポンジチタン）を製造する。このスポンジチタンをプレス成形してチタン消耗電極とし、チタン消耗電極を電極として真空アーク溶解してチタンインゴットを製造する。この際必要に応じて合金元素が添加されて、チタン合金インゴットが製造される。この後、チタン合金インゴットを分塊、鍛造、圧延してチタンスラブとし、さらに、チタンスラブを熱間圧延、焼鈍、酸洗、冷間圧延、および真空熱処理してチタン薄板が製造される。
The titanium material is usually manufactured by the method shown below. First, the raw material titanium oxide is chlorinated to titanium tetrachloride by the crawl method, and then reduced with magnesium or sodium to produce a lump-like sponge-like metal titanium (sponge titanium). This sponge titanium is press-molded to form a titanium consumable electrode, and a titanium ingot is manufactured by vacuum arc melting using the titanium consumable electrode as an electrode. At this time, an alloy element is added as necessary to produce a titanium alloy ingot. Thereafter, the titanium alloy ingot is divided, forged and rolled into a titanium slab, and the titanium slab is further subjected to hot rolling, annealing, pickling, cold rolling, and vacuum heat treatment to produce a titanium thin plate.
また、チタン薄板の製造方法として、チタンインゴットを分塊、水素化粉砕、脱水素、粉末解砕、および分級してチタン粉末を製造し、チタン粉末を粉末圧延、焼結、および冷間圧延して製造する方法も知られる。
In addition, as a method for producing a titanium thin plate, titanium ingot is smashed, hydroground, dehydrogenated, powder crushed, and classified to produce titanium powder, and titanium powder is powder-rolled, sintered, and cold-rolled. The manufacturing method is also known.
特開２０１１－４２８２８号公報（特許文献２）には、チタンインゴットではなくスポンジチタンから直接チタン粉末を製造し、得られるチタン粉末からチタン薄板を製造すべく、チタン金属粉、結着剤、可塑剤、溶剤を含む粘性組成物を薄板状に成形した焼結前成形体を焼結して焼結薄板を製造し、焼結薄板を圧密して焼結圧密薄板を製造し、焼結圧密薄板を再焼結するチタン薄板の製造方法において、焼結薄板の破断伸びを０．４％以上、密度比を８０％以上とし、焼結圧密板の密度比を９０％以上とする方法が開示されている。
Japanese Patent Laid-Open No. 2011-42828 (Patent Document 2) discloses that a titanium powder is produced directly from sponge titanium, not a titanium ingot, and a titanium thin plate is produced from the obtained titanium powder. Sintered compacts are manufactured by sintering pre-sintered compacts made of viscous compositions containing agents and solvents into thin sheets, and sintered compacts are manufactured by compacting the sintered compacts. In the method for producing a titanium thin plate for re-sintering, a method is disclosed in which the fracture elongation of the sintered thin plate is 0.4% or more, the density ratio is 80% or more, and the density ratio of the sintered compacted plate is 90% or more. ing.
特開２０１４－１９９４５号公報（特許文献３）には、チタン合金スクラップまたはチタン合金インゴットを原料としたチタン合金粉に、鉄粉、クロム粉または銅粉を適量添加して複合粉とし、複合粉を炭素鋼カプセル押出し、得られた丸棒の表面のカプセルを溶解除去した後、さらに溶体化処理あるいは、溶体化処理および時効処理を行うことにより、粉末法により品質の優れたチタン合金を製造する方法が開示されている。
Japanese Patent Laid-Open No. 2014-19945 (Patent Document 3) discloses a composite powder obtained by adding an appropriate amount of iron powder, chromium powder or copper powder to titanium alloy powder using titanium alloy scrap or titanium alloy ingot as a raw material. After extruding the carbon steel capsule, the capsule on the surface of the obtained round bar is dissolved and removed, and further solution treatment or solution treatment and aging treatment are performed to produce a titanium alloy with excellent quality by the powder method A method is disclosed.
特開２００１－１３１６０９号公報（特許文献４）には、スポンジチタン粉末を銅製カプセルに充填した後で押出比１．５以上、押出温度７００℃以下で温間押出加工を施して成形し、外側の銅を除く外周加工を施し、成形体の粒界の全長の内２０％以上が金属接触しているチタン成形体を製造する方法が開示されている。
Japanese Patent Laid-Open No. 2001-131609 (Patent Document 4) discloses a method in which a titanium sponge powder is filled in a copper capsule and then subjected to warm extrusion at an extrusion ratio of 1.5 or more and an extrusion temperature of 700 ° C. or less. A method for producing a titanium molded body in which 20% or more of the total length of the grain boundary of the molded body is in metal contact is performed by performing outer peripheral processing excluding copper.
熱間圧延素材を熱間圧延するに際し、熱間圧延素材が純チタンまたはチタン合金のように熱間での延性不足で熱間変形抵抗値が高い、いわゆる難加工材である場合、これらを薄板に圧延する技術としてパック圧延方法が知られている。パック圧延方法とは、加工性の悪いチタン合金などのコア材を加工性の良い安価な炭素鋼などのカバー材で被覆し、熱間圧延する方法である。
When hot-rolling a hot-rolled material, if the hot-rolled material is a so-called difficult-to-process material with high hot deformation resistance due to insufficient hot ductility, such as pure titanium or titanium alloy, these are thin plates. A pack rolling method is known as a technique for rolling the sheet. The pack rolling method is a method in which a core material such as a titanium alloy having poor workability is covered with a cover material such as inexpensive carbon steel having good workability and hot rolling is performed.
具体的には、例えば、コア材の表面に剥離剤を塗布し、少なくともその上下２面をカバー材で被覆するか、または、上下面の他に四周面をスペーサー材により覆い、周りを溶接して組み立て、熱間圧延する。パック圧延では、被圧延材であるコア材をカバー材で覆って熱間圧延する。そのため、コア材表面は冷えた媒体（大気またはロール）に直接触れることがなく、コア材の温度低下を抑制できるため、加工性の悪いコア材でも薄板の製造が可能になる。
Specifically, for example, a release agent is applied to the surface of the core material, and at least two upper and lower surfaces thereof are covered with a cover material, or the four peripheral surfaces are covered with a spacer material in addition to the upper and lower surfaces, and the surroundings are welded. Assembled and hot rolled. In pack rolling, a core material, which is a material to be rolled, is covered with a cover material and hot rolled. Therefore, the core material surface does not directly contact a cold medium (atmosphere or roll), and the temperature drop of the core material can be suppressed, so that even a core material with poor workability can be manufactured.
特開昭６３－２０７４０１号公報（特許文献５）には、密閉被覆箱の組み立て方法が開示され、特開平０９－１３６１０２号公報（特許文献６）には、１０－３ｔｏｒｒオーダー以上の真空度にしてカバー材を密封して密閉被覆箱を製造する方法が開示され、さらに、特開平１１－０５７８１０号公報（特許文献７）には、炭素鋼（カバー材）で覆って１０－２ｔｏｒｒオーダー以下の真空下で高エネルギー密度溶接によって密封し、密閉被覆箱を製造する方法が開示されている。
Japanese Laid-Open Patent Publication No. 63-207401 (Patent Document 5) discloses a method for assembling a hermetically sealed box, and Japanese Laid-Open Patent Publication No. 09-136102 (Patent Document 6) discloses a degree of vacuum of 10 −3 torr or higher. A method for producing a hermetically sealed box by sealing the cover material is disclosed, and further, Japanese Patent Application Laid-Open No. 11-057810 (Patent Document 7) discloses a method of covering the carbon steel (cover material) with an order of 10 −2 torr. A method for producing a hermetic coated box by sealing by high energy density welding under the following vacuum is disclosed.
一方、耐食性の高い素材を安価に製造する方法として、チタン材を母材となる素材表面に接合する方法が知られている。
On the other hand, as a method for producing a highly corrosion-resistant material at a low cost, a method of joining a titanium material to the surface of a material that is a base material is known.
特開平０８－１４１７５４号公報（特許文献８）には、母材として鋼材を用いるとともに合わせ材としてチタンまたはチタン合金を用い、母材と合わせ材の接合面を真空排気した後に溶接して組み立てた圧延用組立スラブを、熱間圧延で接合するチタンクラッド鋼板の製造方法が開示されている。
In Japanese Patent Application Laid-Open No. 08-141754 (Patent Document 8), a steel material is used as a base material and titanium or a titanium alloy is used as a mating material, and the joint surface between the base material and the mating material is evacuated and then welded and assembled. A method for manufacturing a titanium clad steel sheet in which an assembly slab for rolling is joined by hot rolling is disclosed.
特開平１１－１７００７６号公報（特許文献９）には、０．０３質量％以上の炭素を含有する母材鋼材の表面上に、純ニッケル、純鉄および炭素含有量が０．０１質量％以下の低炭素鋼のうちのいずれかからなる厚さ２０μｍ以上のインサート材を介在させてチタン箔材を積層配置した後、その積層方向のいずれか一方側からレーザビームを照射し、チタン箔材の少なくとも縁部近傍を全周にわたって母材鋼材と溶融接合させることによりチタン被覆鋼材を製造する方法が開示されている。
Japanese Patent Laid-Open No. 11-170076 (Patent Document 9) discloses that pure nickel, pure iron, and carbon content are 0.01 mass% or less on the surface of a base steel material containing 0.03 mass% or more of carbon. After the titanium foil material is laminated by interposing an insert material made of any one of the above-mentioned low carbon steels with a thickness of 20 μm or more, a laser beam is irradiated from either side of the lamination direction, A method of manufacturing a titanium-coated steel material by melting and joining at least the vicinity of the edge with a base steel material over the entire circumference is disclosed.
特開２０１５－０４５０４０号公報（特許文献１０）では、鋳塊状に成形された多孔質チタン原料（スポンジチタン）の表面を、真空下で電子ビームを用いて溶解して表層部を稠密なチタンとしたチタン鋳塊を製造し、これを熱間圧延および冷間圧延することにより、多孔質チタン原料が鋳塊状に成形された多孔質部と、稠密なチタンで構成されて多孔質部の全表面を被覆する稠密被覆部とを備える稠密なチタン素材（チタン鋳塊）を非常に少ないエネルギーで製造する方法が例示されている。
In JP-A-2015-045040 (Patent Document 10), the surface of a porous titanium raw material (sponge titanium) formed into an ingot shape is melted using an electron beam under vacuum to make the surface layer portion dense titanium. The titanium ingot is manufactured and hot rolled and cold rolled to form a porous portion in which the porous titanium raw material is formed into an ingot shape, and the entire surface of the porous portion composed of dense titanium. A method for producing a dense titanium material (titanium ingot) having a dense coating portion for coating with very little energy is exemplified.
特開昭６２－２７０２７７号公報（特許文献１１）には、溶射により、自動車用エンジン部材の表面効果処理をすることが記載されている。
Japanese Patent Application Laid-Open No. 62-270277 (Patent Document 11) describes that a surface effect treatment of an engine member for an automobile is performed by thermal spraying.
水素による脆化への対策として、一般に製品に加工後に耐水素吸収性のある表面処理を施すか、または、電気防食を施すことが行われている。しかし、いずれも製品加工または施工の工数が増加するなどして、コスト高になることが避けられず、耐水素脆化性に優れたチタン材を低コストで提供することはできない。
As countermeasures against hydrogen embrittlement, products are generally subjected to surface treatment with hydrogen absorption resistance after processing, or subjected to anticorrosion. However, in any case, it is inevitable that the cost increases due to an increase in the number of processes for product processing or construction, and it is impossible to provide a titanium material excellent in hydrogen embrittlement resistance at a low cost.
また、特許文献１により開示された方法のように、素材全体の５０体積％以上をβ相にするためには、高価な添加元素を多量に含有する必要があるためにコストが上昇する。
In addition, as in the method disclosed in Patent Document 1, in order to make 50% by volume or more of the entire material into a β phase, it is necessary to contain a large amount of expensive additive elements, resulting in an increase in cost.
従来、熱間加工を経てチタン材を製造するに際しては、スポンジチタンをプレス成形してチタン消耗電極とし、チタン消耗電極を電極として真空アーク溶解してチタンインゴットを製造し、さらにチタンインゴットを分塊、鍛造、圧延してチタンスラブとし、チタンスラブを熱間圧延、焼鈍、酸洗、冷間圧延することによって製造されていた。
Conventionally, when manufacturing a titanium material through hot working, sponge titanium is press-molded to form a titanium consumable electrode, and a titanium ingot is manufactured by vacuum arc melting using the titanium consumable electrode as an electrode. The titanium slab was forged and rolled into a titanium slab, and the titanium slab was manufactured by hot rolling, annealing, pickling, and cold rolling.
この場合、チタンを溶解してチタンインゴットを製造する工程が必ず加えられていた。チタン粉末を粉末圧延、焼結、および冷間圧延して製造する方法も知られているが、チタンインゴットからチタン粉末を製造する方法では、やはりチタンを溶解する工程が加えられていた。
In this case, a process of dissolving titanium and producing a titanium ingot was always added. A method of producing titanium powder by powder rolling, sintering, and cold rolling is also known, but in the method of producing titanium powder from a titanium ingot, a step of dissolving titanium is also added.
チタン粉末からチタン材を製造する方法においては、たとえ溶解工程を経ないとしても、高価なチタン粉末を原料として用いるので、得られたチタン材は非常に高価になる。特許文献５～特許文献６に開示された方法でも同様である。
In the method for producing a titanium material from titanium powder, even if it does not go through a melting step, expensive titanium powder is used as a raw material, so that the obtained titanium material becomes very expensive. The same applies to the methods disclosed in Patent Documents 5 to 6.
パック圧延においては、カバー材で被覆されるコア材はあくまでスラブまたはインゴットであって、溶解工程を経ているか、高価なチタン粉末を原料としており、製造コストを低減することはできない。
In pack rolling, the core material covered with the cover material is slab or ingot to the last, and has undergone a melting process or is made of expensive titanium powder, and the manufacturing cost cannot be reduced.
特許文献１０では、非常に少ないエネルギーで稠密なチタン素材を製造することができるものの、鋳塊状に成形されたスポンジチタンの表面を溶解して稠密なチタン表層部および内部の成分は同種の純チタンまたはチタン合金と規定されており、例えば、表層部のみにチタン合金層を均一かつ広範囲に亘って形成することにより製造コストの低下を図ることはできない。
In Patent Document 10, a dense titanium material can be manufactured with very little energy, but the surface of the titanium sponge formed into an ingot shape is dissolved, and the dense titanium surface layer portion and the internal components are the same kind of pure titanium. Or it is prescribed | regulated as a titanium alloy, for example, a manufacturing cost cannot be reduced by forming a titanium alloy layer uniformly only over the surface layer part over a wide range.
一方、安価な耐食素材を製造できる、母材の表面にチタンまたはチタン合金を接合させた素材では、その多くが母材として鋼を選択している。そのため、表面のチタン層が失われると耐食性は損なわれてしまう。仮に、母材にもチタン材を採用したとしても、通常の製造工程を経て製造されるチタン材を用いる限り、抜本的なコスト改善は期待できない。そこで、本発明者らは、工業用純チタンまたはチタン合金からなるスラブの表層に、特定の合金元素を含有する合金層を設け、安価で特定性能に優れたチタン材を得ることを考えた。
On the other hand, many of the materials in which titanium or a titanium alloy is bonded to the surface of the base material that can produce an inexpensive corrosion-resistant material select steel as the base material. Therefore, if the titanium layer on the surface is lost, the corrosion resistance is impaired. Even if a titanium material is adopted as a base material, a drastic cost improvement cannot be expected as long as a titanium material manufactured through a normal manufacturing process is used. Then, the present inventors considered providing an alloy layer containing a specific alloy element on the surface layer of a slab made of industrial pure titanium or a titanium alloy to obtain a titanium material that is inexpensive and excellent in specific performance.
特許文献１１のように、溶射は、金属、セラミックスなどを溶融し、チタン材表面に噴きつけて皮膜を形成させる方法である。この方法で皮膜を形成させた場合、皮膜中の気孔の形成を避けることができない。通常、溶射時には、皮膜の酸化を避けるため、不活性ガスでシールドしながら溶射が行われる。これら不活性ガスは、皮膜の気孔内に巻き込まれる。このような不活性ガスを内包する気孔は、熱間加工などで圧着しない。また、チタンの製造においては、一般的に真空熱処理が実施されるが、この処理時に、気孔内の不活性ガスが膨張して、皮膜が剥がれるおそれがある。本発明者らの経験上、溶射により生じる気孔の存在率（空隙率）は、数ｖｏｌ．％以上となり、溶射条件によっては１０ｖｏｌ．％を超えることもある。このように、皮膜内の空隙率が高いチタン材は、製造工程において剥離する危険性があり、また、加工時の割れなどの欠損が生じるおそれがある。
As in Patent Document 11, thermal spraying is a method in which a film is formed by melting a metal, ceramics, or the like and spraying it on the surface of a titanium material. When a film is formed by this method, the formation of pores in the film cannot be avoided. Usually, during thermal spraying, thermal spraying is performed while shielding with an inert gas in order to avoid oxidation of the film. These inert gases are entrained in the pores of the coating. Such pores containing the inert gas are not pressed by hot working or the like. Further, in the production of titanium, vacuum heat treatment is generally carried out, but during this treatment, the inert gas in the pores may expand and the film may be peeled off. According to the experience of the present inventors, the abundance ratio (porosity) of pores generated by thermal spraying is several vol. % Or more and 10 vol. % May be exceeded. As described above, a titanium material having a high porosity in the film has a risk of peeling in the manufacturing process, and there is a risk that a defect such as a crack during processing may occur.
皮膜の形成方法としては、コールドスプレー法がある。この方法により表面に皮膜を形成する場合も、不活性の高圧ガスが使用される。この方法では、その条件によっては空隙率を１ｖｏｌ．％未満にすることも可能であるものの、気孔の発生を完全に防止することは極めて難しい。そして、溶射の場合と同様に、気孔は不活性ガスを内包しているため、その後の加工によっても消滅しない。また、真空中で熱処理を施した場合、気孔内の不活性ガスが膨張して、皮膜が割れるおそれがある。
There is a cold spray method as a method for forming the film. Even when a film is formed on the surface by this method, an inert high-pressure gas is used. In this method, the porosity is 1 vol. However, it is extremely difficult to completely prevent the generation of pores. As in the case of thermal spraying, since the pores contain the inert gas, they do not disappear even by subsequent processing. In addition, when heat treatment is performed in a vacuum, the inert gas in the pores may expand and the film may break.
熱延時の表面疵を抑制するために、電子ビームを用いてスラブの表層を溶融し、再凝固させる処理として、溶融再凝固処理がある。通常、溶融再凝固した表層は、熱延後の酸洗工程で除去される。このため、従来の溶融再凝固処理では、表層部の合金成分の偏析について全く考慮されていない。
In order to suppress surface flaws during hot rolling, there is a melt resolidification process as a process for melting and resolidifying the surface layer of the slab using an electron beam. Usually, the melted and re-solidified surface layer is removed in a pickling step after hot rolling. For this reason, in the conventional melt resolidification treatment, no consideration is given to the segregation of the alloy components in the surface layer portion.
そこで、本発明者らは、工業用純チタンまたはチタン合金からなるスラブの表面に、特定の合金元素を含有するチタン板を貼り付けたものを熱間圧延用素材とすることにより、安価で特定性能に優れたチタン材を得ることを考えた。
Therefore, the present inventors specify the material for hot rolling at a low price by attaching a titanium plate containing a specific alloy element to the surface of a slab made of industrial pure titanium or titanium alloy. We considered obtaining a titanium material with excellent performance.
本発明は、耐食性、耐酸化性、耐疲労性、耐水素脆化性、中性子遮断性などのチタン材に求められる様々な特性を向上させるために添加する合金元素の含有量（目標特性を発現する特定の合金元素の使用量）を低減し、かつ、チタン材の製造コストを抑制することにより、安価に所望の特性を有するチタン複合材および熱間圧延用チタン材を得ることを目的としている。
In the present invention, the content of alloying elements added to improve various properties required for titanium materials such as corrosion resistance, oxidation resistance, fatigue resistance, hydrogen embrittlement resistance, and neutron barrier properties (express target characteristics) The purpose is to obtain a titanium composite material and hot rolling titanium material having desired characteristics at a low cost by reducing the production amount of a specific alloying element) and suppressing the production cost of the titanium material. .
本発明は、上記課題を解決するためになされたものであり、下記のチタン複合材および熱間圧延用チタン材を要旨とする。
The present invention has been made to solve the above-described problems, and the gist of the present invention is the following titanium composite material and titanium material for hot rolling.
（１）工業用純チタンまたはチタン合金からなる内層と、
前記内層の少なくとも一方の圧延面に形成された前記内層とは異なる化学組成を有する表層と、
前記内層と前記表層との間に形成され、前記内層とは異なる化学組成を有する中間層と、
を備えるチタン複合材であって、
前記表層が、その厚さが２μｍ以上であり、全厚さに占める割合が片面あたり４０％以下であり、
前記表層部の化学組成が、
Ｍｏ、ＶおよびＮｂから選択される一種以上を含有し、下記（１）式で算出されるＭｏ当量が８．０を超え２０．０未満、残部がチタンおよび不純物であり、
前記中間層の厚さが０．５μｍ以上である、
チタン複合材。
Ｍｏ当量＝Ｍｏ含有量（質量％）＋Ｖ含有量（質量％）／１．５＋Ｎｂ含有量（質量％）／３．６ （１） (1) an inner layer made of industrial pure titanium or titanium alloy;
A surface layer having a chemical composition different from that of the inner layer formed on at least one rolling surface of the inner layer;
An intermediate layer formed between the inner layer and the surface layer and having a different chemical composition from the inner layer;
A titanium composite comprising:
The surface layer has a thickness of 2 μm or more, and the proportion of the total thickness is 40% or less per side,
The chemical composition of the surface layer part is
One or more selected from Mo, V and Nb, the Mo equivalent calculated by the following formula (1) is more than 8.0 and less than 20.0, the balance being titanium and impurities,
The intermediate layer has a thickness of 0.5 μm or more.
Titanium composite material.
Mo equivalent = Mo content (% by mass) + V content (% by mass) /1.5+Nb content (% by mass) /3.6 (1)
前記内層の少なくとも一方の圧延面に形成された前記内層とは異なる化学組成を有する表層と、
前記内層と前記表層との間に形成され、前記内層とは異なる化学組成を有する中間層と、
を備えるチタン複合材であって、
前記表層が、その厚さが２μｍ以上であり、全厚さに占める割合が片面あたり４０％以下であり、
前記表層部の化学組成が、
Ｍｏ、ＶおよびＮｂから選択される一種以上を含有し、下記（１）式で算出されるＭｏ当量が８．０を超え２０．０未満、残部がチタンおよび不純物であり、
前記中間層の厚さが０．５μｍ以上である、
チタン複合材。
Ｍｏ当量＝Ｍｏ含有量（質量％）＋Ｖ含有量（質量％）／１．５＋Ｎｂ含有量（質量％）／３．６ （１） (1) an inner layer made of industrial pure titanium or titanium alloy;
A surface layer having a chemical composition different from that of the inner layer formed on at least one rolling surface of the inner layer;
An intermediate layer formed between the inner layer and the surface layer and having a different chemical composition from the inner layer;
A titanium composite comprising:
The surface layer has a thickness of 2 μm or more, and the proportion of the total thickness is 40% or less per side,
The chemical composition of the surface layer part is
One or more selected from Mo, V and Nb, the Mo equivalent calculated by the following formula (1) is more than 8.0 and less than 20.0, the balance being titanium and impurities,
The intermediate layer has a thickness of 0.5 μm or more.
Titanium composite material.
Mo equivalent = Mo content (% by mass) + V content (% by mass) /1.5+Nb content (% by mass) /3.6 (1)
（２）前記内層の圧延面以外の面に、他の表層が形成されており、
前記他の表層が、前記表層と同一の化学組成を備える、
上記（１）のチタン複合材。 (2) Another surface layer is formed on a surface other than the rolled surface of the inner layer,
The other surface layer has the same chemical composition as the surface layer,
The titanium composite material of (1) above.
前記他の表層が、前記表層と同一の化学組成を備える、
上記（１）のチタン複合材。 (2) Another surface layer is formed on a surface other than the rolled surface of the inner layer,
The other surface layer has the same chemical composition as the surface layer,
The titanium composite material of (1) above.
（３）工業用純チタンまたはチタン合金からなる母材と、
前記母材の少なくとも一方の圧延面に接合された表層材と、
前記母材と前記表層材の周囲を接合する溶接部とを備える熱間圧延用チタン材であって、
前記表層材が、前記母材とは異なる化学組成を有し、かつ、
Ｍｏ、ＶおよびＮｂから選択される一種以上を含有し、下記（１）式で算出されるＭｏ当量が８．０を超え２０．０未満、残部がチタンおよび不純物であり、
前記溶接部が、前記母材と前記表層材の界面を外気から遮断する、
熱間圧延用チタン材。
Ｍｏ当量＝Ｍｏ含有量（質量％）＋Ｖ含有量（質量％）／１．５＋Ｎｂ含有量（質量％）／３．６ （１） (3) a base material made of pure industrial titanium or a titanium alloy;
A surface layer material joined to at least one rolling surface of the base material;
A titanium material for hot rolling comprising a welded portion that joins the periphery of the base material and the surface layer material,
The surface layer material has a different chemical composition from the base material, and
One or more selected from Mo, V and Nb, the Mo equivalent calculated by the following formula (1) is more than 8.0 and less than 20.0, the balance being titanium and impurities,
The welded portion shields the interface between the base material and the surface material from outside air;
Titanium material for hot rolling.
Mo equivalent = Mo content (% by mass) + V content (% by mass) /1.5+Nb content (% by mass) /3.6 (1)
前記母材の少なくとも一方の圧延面に接合された表層材と、
前記母材と前記表層材の周囲を接合する溶接部とを備える熱間圧延用チタン材であって、
前記表層材が、前記母材とは異なる化学組成を有し、かつ、
Ｍｏ、ＶおよびＮｂから選択される一種以上を含有し、下記（１）式で算出されるＭｏ当量が８．０を超え２０．０未満、残部がチタンおよび不純物であり、
前記溶接部が、前記母材と前記表層材の界面を外気から遮断する、
熱間圧延用チタン材。
Ｍｏ当量＝Ｍｏ含有量（質量％）＋Ｖ含有量（質量％）／１．５＋Ｎｂ含有量（質量％）／３．６ （１） (3) a base material made of pure industrial titanium or a titanium alloy;
A surface layer material joined to at least one rolling surface of the base material;
A titanium material for hot rolling comprising a welded portion that joins the periphery of the base material and the surface layer material,
The surface layer material has a different chemical composition from the base material, and
One or more selected from Mo, V and Nb, the Mo equivalent calculated by the following formula (1) is more than 8.0 and less than 20.0, the balance being titanium and impurities,
The welded portion shields the interface between the base material and the surface material from outside air;
Titanium material for hot rolling.
Mo equivalent = Mo content (% by mass) + V content (% by mass) /1.5+Nb content (% by mass) /3.6 (1)
（４）前記母材の圧延面以外の面に、他の表層材が接合されており、
前記他の表層材が、前記表層材と同一の化学組成を備える、
上記（３）の熱間圧延用チタン材。 (4) Other surface material is joined to a surface other than the rolling surface of the base material,
The other surface layer material has the same chemical composition as the surface layer material,
The titanium material for hot rolling according to (3) above.
前記他の表層材が、前記表層材と同一の化学組成を備える、
上記（３）の熱間圧延用チタン材。 (4) Other surface material is joined to a surface other than the rolling surface of the base material,
The other surface layer material has the same chemical composition as the surface layer material,
The titanium material for hot rolling according to (3) above.
（５）前記母材が、直接鋳造スラブからなる、
上記（３）または（４）の熱間圧延用チタン材。 (5) The base material comprises a direct cast slab.
The titanium material for hot rolling according to the above (3) or (4).
上記（３）または（４）の熱間圧延用チタン材。 (5) The base material comprises a direct cast slab.
The titanium material for hot rolling according to the above (3) or (4).
（６）前記直接鋳造スラブが、表面の少なくとも一部に溶融再凝固層を形成したものである、
上記（５）の熱間圧延用チタン材。 (6) The directly cast slab is obtained by forming a melt-resolidified layer on at least a part of the surface.
The titanium material for hot rolling according to (5) above.
上記（５）の熱間圧延用チタン材。 (6) The directly cast slab is obtained by forming a melt-resolidified layer on at least a part of the surface.
The titanium material for hot rolling according to (5) above.
（７）前記溶融再凝固層の化学組成が、前記直接鋳造スラブの板厚中心部の化学組成とは異なる、
上記（６）熱間圧延用チタン材。 (7) The chemical composition of the melt-resolidified layer is different from the chemical composition of the center portion of the thickness of the direct cast slab,
(6) Titanium material for hot rolling.
上記（６）熱間圧延用チタン材。 (7) The chemical composition of the melt-resolidified layer is different from the chemical composition of the center portion of the thickness of the direct cast slab,
(6) Titanium material for hot rolling.
本発明に係るチタン複合材は、工業用純チタンまたはチタン合金からなる内層と、内層とは異なる化学組成を有する表層を備えるものであるから、全体が同一のチタン合金からなるチタン材と比較して、同等の特性を有するが、安価に製造することができる。
Since the titanium composite material according to the present invention includes an inner layer made of industrial pure titanium or a titanium alloy and a surface layer having a chemical composition different from that of the inner layer, the whole is compared with a titanium material made of the same titanium alloy. Thus, it has the same characteristics but can be manufactured at low cost.
本発明者らは、上記課題を解決するために、最終製品のチタン板の表層のみを合金化することにより、目標特性を発現する特定の合金元素の使用量を低減し、かつ、チタン材の製造コストを抑制するべく、鋭意検討を行った結果、工業用純チタンまたはチタン合金からなる母材と母材とは異なる化学組成を有する表層材とを、これらの界面が外気から遮断されるように母材および表層材の周囲を溶接した熱間圧延用チタン材を見出した。この熱間圧延用チタン材を熱間加工して得たチタン複合材は、安価に優れた特性を有するチタン材となる。
In order to solve the above-mentioned problems, the present inventors reduced the amount of a specific alloy element that expresses a target characteristic by alloying only the surface layer of the titanium plate of the final product, and As a result of diligent investigations to reduce the manufacturing cost, the interface between the base material made of industrial pure titanium or titanium alloy and the surface layer material having a chemical composition different from the base material is shielded from the outside air. The titanium material for hot rolling which welded the circumference | surroundings of the base material and the surface layer material was discovered. The titanium composite material obtained by hot working the titanium material for hot rolling becomes a titanium material having excellent properties at low cost.
本発明は上記の知見に基づいてなされたものである。以下、本発明に係るチタン複合材およびその熱間圧延用のチタン材を、図面を参照しながら説明する。なお、以降の説明では、各元素の含有量に関する「％」は特にことわりがない限り「質量％」を意味する。
The present invention has been made based on the above findings. Hereinafter, a titanium composite material and a titanium material for hot rolling thereof according to the present invention will be described with reference to the drawings. In the following description, “%” regarding the content of each element means “mass%” unless otherwise specified.
１．チタン複合材
１－１．全体構成
図１，２に示すように、チタン複合材１，２は、工業用純チタンまたはチタン合金からなる内層５と、内層５の少なくとも一方の圧延面に形成された内層５とは異なる化学組成を有する表層３，４と、内層５と表層３，４との間に形成され、内層５とは異なる化学組成を有する中間層（図示省略）とを備える。なお、図１，２に示す例では、内層５の一方または両方の圧延面に表層を形成した例を示しているが、内層５の圧延面以外の面（図１，２に示す例では側面）に他の表層（図示省略）を設けてもよい。以下、表層、内層、中間層を順次説明する。 1. Titanium composite 1-1. Overall Configuration As shown in FIGS. 1 and 2,titanium composites 1 and 2 are different in chemical composition from inner layer 5 made of industrial pure titanium or titanium alloy and inner layer 5 formed on at least one rolling surface of inner layer 5. The surface layers 3 and 4 which have a composition, and the intermediate | middle layer (illustration omitted) which is formed between the inner layer 5 and the surface layers 3 and 4 and has a chemical composition different from the inner layer 5 is provided. In the example shown in FIGS. 1 and 2, an example is shown in which a surface layer is formed on one or both rolling surfaces of the inner layer 5, but a surface other than the rolling surface of the inner layer 5 (side surface in the example shown in FIGS. 1 and 2). ) May be provided with another surface layer (not shown). Hereinafter, the surface layer, the inner layer, and the intermediate layer will be sequentially described.
１－１．全体構成
図１，２に示すように、チタン複合材１，２は、工業用純チタンまたはチタン合金からなる内層５と、内層５の少なくとも一方の圧延面に形成された内層５とは異なる化学組成を有する表層３，４と、内層５と表層３，４との間に形成され、内層５とは異なる化学組成を有する中間層（図示省略）とを備える。なお、図１，２に示す例では、内層５の一方または両方の圧延面に表層を形成した例を示しているが、内層５の圧延面以外の面（図１，２に示す例では側面）に他の表層（図示省略）を設けてもよい。以下、表層、内層、中間層を順次説明する。 1. Titanium composite 1-1. Overall Configuration As shown in FIGS. 1 and 2,
表層の厚さが薄すぎると、所望の特性が十分に得られない。一方、厚すぎると、チタン複合材全体に占めるチタン合金の割合が増すため、コストメリットが小さくなる。そのため、その厚さは２μｍ以上とし、全厚さに占める割合は片面あたり４０％以下とする。
If the surface layer is too thin, the desired characteristics cannot be obtained sufficiently. On the other hand, if it is too thick, the proportion of the titanium alloy in the entire titanium composite increases, so the cost merit decreases. Therefore, the thickness is 2 μm or more, and the proportion of the total thickness is 40% or less per side.
１－２．表層
（厚さ）
表層のうち外部環境に接する表層の厚さが薄過ぎると、耐水素吸収性が十分に得られない。一方、表層のチタン合金が厚い場合には耐水素吸収性には問題はないが、素材全体に占める表層のチタン合金の割合が増すため、製造コストが嵩む。表層の厚さは、５μｍ以上であることが望ましく、１０μｍ以上であることがより望ましい。チタン複合材の全厚さに対する表層の厚さの割合は、片面あたり４０％以下とし、３０％以下であることがより望ましく、特に、２～２０％とするのがよい。 1-2. Surface layer (thickness)
If the thickness of the surface layer in contact with the external environment is too thin, sufficient hydrogen absorption resistance cannot be obtained. On the other hand, when the surface layer titanium alloy is thick, there is no problem in hydrogen absorption resistance, but the proportion of the surface layer titanium alloy in the entire material increases, so the manufacturing cost increases. The thickness of the surface layer is preferably 5 μm or more, and more preferably 10 μm or more. The ratio of the thickness of the surface layer to the total thickness of the titanium composite is 40% or less per side, more preferably 30% or less, and particularly preferably 2 to 20%.
（厚さ）
表層のうち外部環境に接する表層の厚さが薄過ぎると、耐水素吸収性が十分に得られない。一方、表層のチタン合金が厚い場合には耐水素吸収性には問題はないが、素材全体に占める表層のチタン合金の割合が増すため、製造コストが嵩む。表層の厚さは、５μｍ以上であることが望ましく、１０μｍ以上であることがより望ましい。チタン複合材の全厚さに対する表層の厚さの割合は、片面あたり４０％以下とし、３０％以下であることがより望ましく、特に、２～２０％とするのがよい。 1-2. Surface layer (thickness)
If the thickness of the surface layer in contact with the external environment is too thin, sufficient hydrogen absorption resistance cannot be obtained. On the other hand, when the surface layer titanium alloy is thick, there is no problem in hydrogen absorption resistance, but the proportion of the surface layer titanium alloy in the entire material increases, so the manufacturing cost increases. The thickness of the surface layer is preferably 5 μm or more, and more preferably 10 μm or more. The ratio of the thickness of the surface layer to the total thickness of the titanium composite is 40% or less per side, more preferably 30% or less, and particularly preferably 2 to 20%.
（化学成分）
本発明に係るチタン複合材１では、表層の少なくとも一方（少なくとも外部環境に接する表層）の耐水素吸収性を高めるために、以下に掲げる各種合金元素を含有させてもよい。 (Chemical composition)
In the titanium composite material 1 according to the present invention, in order to improve the hydrogen absorption resistance of at least one of the surface layers (at least the surface layer in contact with the external environment), various alloy elements listed below may be included.
本発明に係るチタン複合材１では、表層の少なくとも一方（少なくとも外部環境に接する表層）の耐水素吸収性を高めるために、以下に掲げる各種合金元素を含有させてもよい。 (Chemical composition)
In the titanium composite material 1 according to the present invention, in order to improve the hydrogen absorption resistance of at least one of the surface layers (at least the surface layer in contact with the external environment), various alloy elements listed below may be included.
８．０＜Ｍｏ当量＜２０．０
ただし、Ｍｏ当量＝Ｍｏ含有量（質量％）＋Ｖ含有量（質量％）／１．５＋Ｎｂ含有量（質量％）／３．６である。
耐水素吸収性を得る層は、β安定化元素を一定範囲含有するチタン合金層である。β相を形成することを規定する理由は、チタンのα相はわずか数１０ｐｐｍの水素濃度でも水素化物を形成するのに対し、チタン合金のβ相はおおよそ１０００ｐｐｍ以上の水素を固溶できるため、水素起因による脆化を生じ難い特徴を有するためである。 8.0 <Mo equivalent <20.0
However, Mo equivalent = Mo content (mass%) + V content (mass%) / 1.5 + Nb content (mass%) / 3.6.
The layer for obtaining hydrogen absorption resistance is a titanium alloy layer containing a certain range of β-stabilizing elements. The reason for prescribing the formation of the β phase is that the α phase of titanium forms a hydride even at a hydrogen concentration of only a few tens of ppm, whereas the β phase of the titanium alloy can dissolve about 1000 ppm or more of hydrogen, This is because it has the characteristic that it is difficult to cause embrittlement due to hydrogen.
ただし、Ｍｏ当量＝Ｍｏ含有量（質量％）＋Ｖ含有量（質量％）／１．５＋Ｎｂ含有量（質量％）／３．６である。
耐水素吸収性を得る層は、β安定化元素を一定範囲含有するチタン合金層である。β相を形成することを規定する理由は、チタンのα相はわずか数１０ｐｐｍの水素濃度でも水素化物を形成するのに対し、チタン合金のβ相はおおよそ１０００ｐｐｍ以上の水素を固溶できるため、水素起因による脆化を生じ難い特徴を有するためである。 8.0 <Mo equivalent <20.0
However, Mo equivalent = Mo content (mass%) + V content (mass%) / 1.5 + Nb content (mass%) / 3.6.
The layer for obtaining hydrogen absorption resistance is a titanium alloy layer containing a certain range of β-stabilizing elements. The reason for prescribing the formation of the β phase is that the α phase of titanium forms a hydride even at a hydrogen concentration of only a few tens of ppm, whereas the β phase of the titanium alloy can dissolve about 1000 ppm or more of hydrogen, This is because it has the characteristic that it is difficult to cause embrittlement due to hydrogen.
Ｆｅ、Ｃｒなどの共析型のβ安定化元素を含む場合には、チタンとそれらの元素が化合物を形成して、脆化を招くおそれがある。しかし、β安定化元素のうち、Ｍｏ、ＶおよびＮｂを「８．０＜Ｍｏ当量＜２０．０」を満たす範囲で含有する場合には、ＦｅおよびＣｒなどが同時に存在していてもβ相が安定し、化合物相を形成しないため脆化を生じない。
In the case where a eutectoid β-stabilizing element such as Fe or Cr is contained, there is a possibility that titanium and these elements form a compound and cause embrittlement. However, among the β-stabilizing elements, when Mo, V, and Nb are contained in a range that satisfies “8.0 <Mo equivalent <20.0”, the β-phase may be present even if Fe and Cr are present at the same time. Is stable and does not form a compound phase, and thus does not cause embrittlement.
ここで、Ｍｏ当量の下限は、充分な量のβ相を得るために必要な合金量である。上限は、合金添加量が多いチタン合金は価格が高いため、コスト面から使用に適さないことから定めた。
Here, the lower limit of the Mo equivalent is the amount of alloy necessary to obtain a sufficient amount of β phase. The upper limit was determined because a titanium alloy with a large amount of alloy addition is not suitable for use because of its high cost.
表層の合金層の形成には、既存のβ型チタン合金を利用することができる。例えば、Ｔｉ－１５Ｖ－３Ｃｒ－３Ａｌ－３Ｓｎ、Ｔｉ－８Ｖ－３Ａｌ－６Ｃｒ－４Ｍｏ－４Ｚｒ（ＢｅｔａＣ）、Ｔｉ－１１．５Ｍｏ－６Ｚｒ－４．５Ｓｎ（ＢｅｔａIII）である。このような既存のβ型チタン合金を用いた場合、上記元素以外のＣｒ、Ｓｎ、Ａｌ、Ｚｒなどの添加元素の含有も、総量が１５％以下であれば許容される。これらの元素は、既存のβ型チタン合金において熱処理性、強度および冷間加工性を調整するために含まれる元素であり、本発明で定義するＭｏ当量を下げないからである。また、例えば、Ｓｉ、Ｆｅ等をさらに含有してもよい。
The existing β-type titanium alloy can be used for forming the surface alloy layer. For example, Ti-15V-3Cr-3Al-3Sn, Ti-8V-3Al-6Cr-4Mo-4Zr (BetaC), Ti-11.5Mo-6Zr-4.5Sn (BetaIII). When such an existing β-type titanium alloy is used, inclusion of additive elements such as Cr, Sn, Al, and Zr other than the above elements is allowed if the total amount is 15% or less. This is because these elements are elements included for adjusting heat treatment property, strength, and cold workability in the existing β-type titanium alloy, and do not lower the Mo equivalent defined in the present invention. Further, for example, Si, Fe and the like may be further contained.
上記以外の残部は、不純物である。不純物としては、目標特性を阻害しない範囲で含有することができ、その他の不純物は主にスクラップから混入する不純物元素としてＴａ、Ｓｉ、ＭｎおよびＣｕ等があり、一般的な不純物元素であるＣ、Ｎ、Ｆｅ、ＯおよびＨと併せて、総量で５％以下許容される。
The remainder other than the above is impurities. Impurities can be contained within a range that does not hinder the target characteristics, and other impurities include Ta, Si, Mn, and Cu as impurity elements mainly mixed from scrap, and C, which are general impurity elements, In combination with N, Fe, O and H, a total amount of 5% or less is allowed.
１－３．内層
内層５には、工業用純チタンまたはチタン合金からなる。例えば、内層５に工業用純チタンを用いると、全体が同一のチタン合金からなるチタン材と比べて、室温での加工性に優れる。 1-3. Inner layer Theinner layer 5 is made of industrial pure titanium or a titanium alloy. For example, when industrial pure titanium is used for the inner layer 5, the processability at room temperature is excellent as compared with a titanium material made entirely of the same titanium alloy.
内層５には、工業用純チタンまたはチタン合金からなる。例えば、内層５に工業用純チタンを用いると、全体が同一のチタン合金からなるチタン材と比べて、室温での加工性に優れる。 1-3. Inner layer The
なお、ここでいう工業用純チタンは、ＪＩＳ規格の１種～４種、およびそれに対応するＡＳＴＭ規格のＧｒａｄｅ１～４、ＤＩＮ規格の３・７０２５，３・７０３５、３・７０５５で規定される工業用純チタンを含むものとする。すなわち、本発明で対象とする工業用純チタンは、例えば、Ｃ：０．１％以下、Ｈ：０．０１５％以下、Ｏ：０．４％以下、Ｎ：０．０７％以下、Ｆｅ：０．５％以下、残部Ｔｉからなるものである。
The industrial pure titanium mentioned here is an industry defined by JIS standards 1 to 4 and ASTM standards Grades 1 to 4 and DIN standards 3, 7025, 3, 7035, and 37055. Contains pure titanium. That is, the industrial pure titanium targeted in the present invention is, for example, C: 0.1% or less, H: 0.015% or less, O: 0.4% or less, N: 0.07% or less, Fe: It consists of 0.5% or less and the balance Ti.
また、特定の性能に加え、強度も要求される用途に供される場合には、内層５にチタン合金を用いてもよい。表層のＭｏ等の含有量を高めるとともに内層５をチタン合金により構成することにより、合金コストを大幅に削減できるとともに、高強度を得ることができる。
In addition, in a case where the strength is required in addition to the specific performance, a titanium alloy may be used for the inner layer 5. By increasing the content of Mo or the like in the surface layer and configuring the inner layer 5 with a titanium alloy, the alloy cost can be significantly reduced and high strength can be obtained.
内層５をなすチタン合金には、必要とする用途に応じて、α型チタン合金、α＋β型チタン合金、β型チタン合金のいずれも用いることが可能である。
As the titanium alloy forming the inner layer 5, any of an α-type titanium alloy, an α + β-type titanium alloy, and a β-type titanium alloy can be used according to a required application.
ここで、α型チタン合金としては、例えば高耐食性合金（ＡＳＴＭ Ｇｒａｄｅ ７、１１、１６、２６、１３、３０、３３あるいはこれらに対応するＪＩＳ種や更に種々の元素を少量含有させたチタン材）、Ｔｉ－０．５Ｃｕ、Ｔｉ－１．０Ｃｕ、Ｔｉ－１．０Ｃｕ－０．５Ｎｂ、Ｔｉ－１．０Ｃｕ－１．０Ｓｎ－０．３Ｓｉ－０．２５Ｎｂ、Ｔｉ－０．５Ａｌ－０．４５Ｓｉ、Ｔｉ－０．９Ａｌ－０．３５Ｓｉ、Ｔｉ－３Ａｌ－２．５Ｖ、Ｔｉ－５Ａｌ－２．５Ｓｎ、Ｔｉ－６Ａｌ－２Ｓｎ－４Ｚｒ－２Ｍｏ、Ｔｉ－６Ａｌ－２．７５Ｓｎ－４Ｚｒ－０．４Ｍｏ－０．４５Ｓｉなどを用いることができる。
Here, as the α-type titanium alloy, for example, a high corrosion resistance alloy (ASTM Grade 7, 11, 16, 26, 13, 30, 33, or a titanium material containing a small amount of JIS species corresponding thereto and various elements). Ti-0.5Cu, Ti-1.0Cu, Ti-1.0Cu-0.5Nb, Ti-1.0Cu-1.0Sn-0.3Si-0.25Nb, Ti-0.5Al-0.45Si Ti-0.9Al-0.35Si, Ti-3Al-2.5V, Ti-5Al-2.5Sn, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2.75Sn-4Zr-0.4Mo -0.45Si or the like can be used.
α＋β型チタン合金としては、例えば、Ｔｉ－６Ａｌ－４Ｖ、Ｔｉ－６Ａｌ－６Ｖ－２Ｓｎ、Ｔｉ－６Ａｌ－７Ｖ、Ｔｉ－３Ａｌ－５Ｖ、Ｔｉ－５Ａｌ－２Ｓｎ－２Ｚｒ－４Ｍｏ－４Ｃｒ、Ｔｉ－６Ａｌ－２Ｓｎ－４Ｚｒ－６Ｍｏ、Ｔｉ－１Ｆｅ－０．３５Ｏ、Ｔｉ－１．５Ｆｅ－０．５Ｏ、Ｔｉ－５Ａｌ－１Ｆｅ、Ｔｉ－５Ａｌ－１Ｆｅ－０．３Ｓｉ、Ｔｉ－５Ａｌ－２Ｆｅ、Ｔｉ－５Ａｌ－２Ｆｅ－０．３Ｓｉ、Ｔｉ－５Ａｌ－２Ｆｅ－３Ｍｏ、Ｔｉ－４．５Ａｌ－２Ｆｅ－２Ｖ－３Ｍｏなどを用いることができる。
Examples of α + β type titanium alloys include Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-6Al-7V, Ti-3Al-5V, Ti-5Al-2Sn-2Zr-4Mo-4Cr, Ti-6Al. -2Sn-4Zr-6Mo, Ti-1Fe-0.35O, Ti-1.5Fe-0.5O, Ti-5Al-1Fe, Ti-5Al-1Fe-0.3Si, Ti-5Al-2Fe, Ti-5Al -2Fe-0.3Si, Ti-5Al-2Fe-3Mo, Ti-4.5Al-2Fe-2V-3Mo, or the like can be used.
さらに、β型チタン合金としては、例えば、Ｔｉ－１１．５Ｍｏ－６Ｚｒ－４．５Ｓｎ，Ｔｉ－８Ｖ－３Ａｌ－６Ｃｒ－４Ｍｏ－４Ｚｒ，Ｔｉ－１０Ｖ－２Ｆｅ－３Ｍｏ，Ｔｉ－１３Ｖ－１１Ｃｒ－３Ａｌ，Ｔｉ－１５Ｖ－３Ａｌ－３Ｃｒ－３Ｓｎ，Ｔｉ－６．８Ｍｏ－４．５Ｆｅ－１．５Ａｌ、Ｔｉ－２０Ｖ－４Ａｌ－１Ｓｎ、Ｔｉ－２２Ｖ－４Ａｌな どを用いることができる。
Further, as the β-type titanium alloy, for example, Ti-11.5Mo-6Zr-4.5Sn, Ti-8V-3Al-6Cr-4Mo-4Zr, Ti-10V-2Fe-3Mo, Ti-13V-11Cr-3Al Ti-15V-3Al-3Cr-3Sn, Ti-6.8Mo-4.5Fe-1.5Al, Ti-20V-4Al-1Sn, Ti-22V-4Al, and the like can be used.
ただし、内層５の０．２％耐力が１０００ＭＰａを超えると、加工性が悪化し、例えば、曲げ加工時に割れが生じる恐れがある。そのため、内層５に用いるチタンおよびチタン合金は、０．２％耐力が１０００ＭＰａ以下であることが望ましい。
However, if the 0.2% proof stress of the inner layer 5 exceeds 1000 MPa, the workability deteriorates, and for example, there is a risk of cracking during bending. Therefore, the titanium and titanium alloy used for the inner layer 5 desirably have a 0.2% proof stress of 1000 MPa or less.
１－４．中間層
本発明のチタン複合材は、前記内層と前記表層との間に中間層を備えている。すなわち、後述する熱間圧延用チタン材は、母材に表層材を貼り付け周囲を溶接したものであるが、その後の熱延加熱時、および、冷延後の熱処理工程において、母材と表層材との界面で拡散が生じ、最終的にチタン複合材に仕上げた時には、上記母材由来の内層と、上記表層材由来の表層との間には中間層が形成される。この中間層は、母材の化学組成とは異なる化学組成を有している。この中間層が、上記内層と上記表層とを金属結合させ、強固に接合する。また、中間層では連続した元素勾配を生じるため、上記内層と上記表層との強度差を和らげることができ、加工時の割れを抑制することができる。 1-4. Intermediate Layer The titanium composite material of the present invention includes an intermediate layer between the inner layer and the surface layer. That is, a titanium material for hot rolling, which will be described later, is a material in which a surface layer material is attached to a base material and the periphery thereof is welded. During the subsequent hot rolling and heat treatment processes after cold rolling, the base material and the surface layer When diffusion occurs at the interface with the material and the titanium composite material is finally finished, an intermediate layer is formed between the inner layer derived from the base material and the surface layer derived from the surface material. This intermediate layer has a chemical composition different from the chemical composition of the base material. This intermediate layer bonds the inner layer and the surface layer to each other and bonds them firmly. Further, since a continuous element gradient is generated in the intermediate layer, the difference in strength between the inner layer and the surface layer can be reduced, and cracks during processing can be suppressed.
本発明のチタン複合材は、前記内層と前記表層との間に中間層を備えている。すなわち、後述する熱間圧延用チタン材は、母材に表層材を貼り付け周囲を溶接したものであるが、その後の熱延加熱時、および、冷延後の熱処理工程において、母材と表層材との界面で拡散が生じ、最終的にチタン複合材に仕上げた時には、上記母材由来の内層と、上記表層材由来の表層との間には中間層が形成される。この中間層は、母材の化学組成とは異なる化学組成を有している。この中間層が、上記内層と上記表層とを金属結合させ、強固に接合する。また、中間層では連続した元素勾配を生じるため、上記内層と上記表層との強度差を和らげることができ、加工時の割れを抑制することができる。 1-4. Intermediate Layer The titanium composite material of the present invention includes an intermediate layer between the inner layer and the surface layer. That is, a titanium material for hot rolling, which will be described later, is a material in which a surface layer material is attached to a base material and the periphery thereof is welded. During the subsequent hot rolling and heat treatment processes after cold rolling, the base material and the surface layer When diffusion occurs at the interface with the material and the titanium composite material is finally finished, an intermediate layer is formed between the inner layer derived from the base material and the surface layer derived from the surface material. This intermediate layer has a chemical composition different from the chemical composition of the base material. This intermediate layer bonds the inner layer and the surface layer to each other and bonds them firmly. Further, since a continuous element gradient is generated in the intermediate layer, the difference in strength between the inner layer and the surface layer can be reduced, and cracks during processing can be suppressed.
なお、中間層の厚さは、ＥＰＭＡまたはＧＤＳを用いて測定することができる。ＧＤＳを用いればより詳細な測定が可能である。ＧＤＳの場合は表層をある程度、研磨で除去した後、表面から深さ方向にＧＤＳ分析を行うことで中間層の厚みを測定することが可能である。中間層とは、母材からの増加含有量（母材には含まれない元素の場合は、その含有量、母材にも含まれる元素の場合には、母材からの含有量の増加分）をＣMIDとし、表層部における増加含有量の平均をＣAVEとするとき、０＜ＣMID≦０．８×ＣAVEの領域を意味する。
The thickness of the intermediate layer can be measured using EPMA or GDS. If GDS is used, more detailed measurement is possible. In the case of GDS, after removing the surface layer to some extent by polishing, the thickness of the intermediate layer can be measured by performing GDS analysis in the depth direction from the surface. The intermediate layer is the increased content from the base material (in the case of an element not included in the base material, its content, in the case of an element also included in the base material, the increase in content from the base material) ) Is C MID, and the average of the increased content in the surface layer portion is C AVE , it means a region of 0 <C MID ≦ 0.8 × C AVE .
この中間層の厚さは、０．５μｍ以上とする。一方、中間層の厚みが大きくなり過ぎると、その分だけ表層の合金層が薄くなってしまい効果を発現しない場合がある。よって、その上限は１５μｍとするのがよい。
The thickness of this intermediate layer is 0.5 μm or more. On the other hand, if the thickness of the intermediate layer becomes too large, the surface alloy layer may become thin by that amount, and the effect may not be exhibited. Therefore, the upper limit is preferably 15 μm.
２．熱間圧延用チタン材
本発明の熱間圧延用チタン材は、熱間加工に供される素材（スラブ、ブルーム、ビレットなどの鋳片）であり、熱間加工後、必要に応じて、冷間加工、熱処理などを施して、チタン複合材に加工される。以下、図面を用いて、本発明本発明の熱間圧延用チタン材を説明する。また、以下の説明において、各元素の含有量に関する「％」は「質量％」を意味する。 2. Titanium material for hot rolling The titanium material for hot rolling of the present invention is a material (slab of slab, bloom, billet, etc.) used for hot working, and after hot working, it can be cooled if necessary. It is processed into a titanium composite material by performing inter-processing, heat treatment, etc. Hereinafter, the titanium material for hot rolling according to the present invention will be described with reference to the drawings. In the following description, “%” regarding the content of each element means “mass%”.
本発明の熱間圧延用チタン材は、熱間加工に供される素材（スラブ、ブルーム、ビレットなどの鋳片）であり、熱間加工後、必要に応じて、冷間加工、熱処理などを施して、チタン複合材に加工される。以下、図面を用いて、本発明本発明の熱間圧延用チタン材を説明する。また、以下の説明において、各元素の含有量に関する「％」は「質量％」を意味する。 2. Titanium material for hot rolling The titanium material for hot rolling of the present invention is a material (slab of slab, bloom, billet, etc.) used for hot working, and after hot working, it can be cooled if necessary. It is processed into a titanium composite material by performing inter-processing, heat treatment, etc. Hereinafter, the titanium material for hot rolling according to the present invention will be described with reference to the drawings. In the following description, “%” regarding the content of each element means “mass%”.
２－１．全体構成
図３は、母材（チタン矩形鋳片、スラブ）６と表層材（チタン板）７を真空中で溶接することにより貼り合わせることを模式的に示す説明図であり、図４は、母材（チタン矩形鋳片、スラブ）６の表面（圧延面）だけでなく側面（圧延面以外の面）にも表層材（チタン板）７，８を溶接することにより貼り合わせることを模式的に示す説明図である。 2-1. Overall Configuration FIG. 3 is an explanatory view schematically showing that the base material (titanium rectangular cast, slab) 6 and the surface layer material (titanium plate) 7 are bonded together in a vacuum, and FIG. It is typical to bond the surface materials (titanium plates) 7 and 8 not only to the surface (rolled surface) of the base material (titanium rectangular cast slab, slab) but also to the side surfaces (surfaces other than the rolled surface). It is explanatory drawing shown in.
図３は、母材（チタン矩形鋳片、スラブ）６と表層材（チタン板）７を真空中で溶接することにより貼り合わせることを模式的に示す説明図であり、図４は、母材（チタン矩形鋳片、スラブ）６の表面（圧延面）だけでなく側面（圧延面以外の面）にも表層材（チタン板）７，８を溶接することにより貼り合わせることを模式的に示す説明図である。 2-1. Overall Configuration FIG. 3 is an explanatory view schematically showing that the base material (titanium rectangular cast, slab) 6 and the surface layer material (titanium plate) 7 are bonded together in a vacuum, and FIG. It is typical to bond the surface materials (titanium plates) 7 and 8 not only to the surface (rolled surface) of the base material (titanium rectangular cast slab, slab) but also to the side surfaces (surfaces other than the rolled surface). It is explanatory drawing shown in.
本発明では、図３，４に示すように、母材であるスラブ６の表面に特性を発現する合金元素を含有したチタン板７，８を貼り合わせた後、熱延クラッド法により接合させることによりチタン複合材１，２の表層を合金化する。
In the present invention, as shown in FIGS. 3 and 4, titanium plates 7 and 8 containing alloy elements that exhibit characteristics are bonded to the surface of a slab 6 that is a base material, and then bonded by hot rolling cladding. Thus, the surface layers of the titanium composite materials 1 and 2 are alloyed.
図１に示すチタン複合材１を製造する場合には、図３に示すようにスラブ６の片面にのみチタン板７を真空中で貼り合わせればよく、スラブ６のもう片面にはチタン板７を貼り付けずに熱間圧延してもよい。
When the titanium composite material 1 shown in FIG. 1 is manufactured, a titanium plate 7 may be bonded to only one side of the slab 6 in a vacuum as shown in FIG. 3, and the titanium plate 7 is attached to the other side of the slab 6. You may hot-roll without sticking.
図４に示すように、スラブ６の片面とともにもう片面にもチタン板７を貼り合わせてもよい。これにより、上述したように熱間圧延工程での熱延疵の発生を抑制できる。
As shown in FIG. 4, a titanium plate 7 may be bonded to one side of the slab 6 as well as the other side. Thereby, generation | occurrence | production of the hot rolling in a hot rolling process can be suppressed as mentioned above.
さらに、図２に示すチタン複合材２を製造する場合には、図４に示すようにスラブ６の両圧延面に合金元素を含有する板を貼り合わせればよい。
Furthermore, when the titanium composite material 2 shown in FIG. 2 is manufactured, a plate containing an alloy element may be bonded to both rolling surfaces of the slab 6 as shown in FIG.
さらに、図４に示すように、熱間圧延時のエッジ側となるスラブ６の側面についても、圧延面と同様に同一規格のチタン板８を真空中で貼り合わせて溶接してもよい。
Furthermore, as shown in FIG. 4, the same standard titanium plate 8 may be bonded together in a vacuum and welded to the side surface of the slab 6 that becomes the edge side during hot rolling.
すなわち、熱間圧延においては、通常、スラブ６に圧下が加えられることによって、スラブ６の側面の少なくとも一部が熱延板の表面側に回り込む。そのため、スラブ６の側面の表層の組織が粗大であったり、多数の欠陥が存在していたりすると、熱延板の幅方向の両端近くの表面に表面疵が発生する可能性がある。このため、スラブ６の側面にもチタン板８を真空中で貼り合わせて溶接することによって、熱延板の幅方向の両端近くの表面における表面疵の発生を有効に防止できる。
That is, in hot rolling, usually, when the slab 6 is subjected to reduction, at least a part of the side surface of the slab 6 wraps around the surface side of the hot-rolled sheet. Therefore, if the structure of the surface layer on the side surface of the slab 6 is coarse or a large number of defects exist, surface flaws may occur on the surface near both ends in the width direction of the hot-rolled sheet. For this reason, generation | occurrence | production of the surface flaw in the surface near the both ends of the width direction of a hot-rolled sheet can be effectively prevented by bonding the titanium plate 8 to the side surface of the slab 6 and welding it.
なお、熱間圧延時にスラブ６の側面が回り込む量は、製造方法により異なるが、通常は２０～３０ｍｍ程度であるため、スラブ６の側面全面にチタン板８を貼り付ける必要はなく、製造方法に則した回り込み量に相当する部分にのみチタン板８を貼り付ければよい。
The amount of the side surface of the slab 6 that wraps around during hot rolling varies depending on the manufacturing method, but is usually about 20 to 30 mm. Therefore, it is not necessary to attach the titanium plate 8 to the entire side surface of the slab 6, and the manufacturing method is not limited. It is only necessary to attach the titanium plate 8 only to the portion corresponding to the sneak amount.
２－２．表層材
チタン複合材１，２を製造する際には、熱間圧延により形成した酸化層を除去するため、熱間圧延後にショット－酸洗の工程を経て製造される。しかしながら、この工程の際に熱延クラッドにより形成した表層が除去されてしまうと、所望の特性を発現させることができない。 2-2. Surface material When thetitanium composites 1 and 2 are manufactured, they are manufactured through a shot-pickling process after hot rolling in order to remove the oxide layer formed by hot rolling. However, if the surface layer formed by the hot-rolled cladding is removed during this step, desired characteristics cannot be expressed.
チタン複合材１，２を製造する際には、熱間圧延により形成した酸化層を除去するため、熱間圧延後にショット－酸洗の工程を経て製造される。しかしながら、この工程の際に熱延クラッドにより形成した表層が除去されてしまうと、所望の特性を発現させることができない。 2-2. Surface material When the
また、チタン複合材１，２の表層の厚みが薄くなり過ぎると、狙いとする所望の特性を発現しなくなってしまう。一方で、表層の厚みが厚過ぎると、その分だけ製造コストが増加する。チタン複合材１，２が使用目的に合わせた表層の厚みを有すればよいことから、素材として使用するチタン板７，８の厚さは、特に限定する必要はないが、スラブ６の厚みの５～４０％の範囲にあることが好ましい。
Also, if the thickness of the surface layer of the titanium composites 1 and 2 becomes too thin, the desired desired characteristics will not be exhibited. On the other hand, if the thickness of the surface layer is too thick, the manufacturing cost increases accordingly. Since the titanium composite materials 1 and 2 only have to have a surface layer thickness suitable for the purpose of use, the thickness of the titanium plates 7 and 8 used as the material is not particularly limited, but the thickness of the slab 6 It is preferably in the range of 5 to 40%.
表層材（チタン板）としては、前記のチタン複合材の表層の項で説明した所定の化学組成を有するチタン板を用いる。特に、チタン板の化学組成は、熱間圧延での板破断を抑制するため、上記の母材と同様の成分を基本とし、これに所定の元素が含有されている成分に調整することが望ましい。
As the surface layer material (titanium plate), a titanium plate having the predetermined chemical composition described in the section of the surface layer of the titanium composite material is used. In particular, it is desirable to adjust the chemical composition of the titanium plate to a component containing a predetermined element in the same component as the base material in order to suppress the plate breakage during hot rolling. .
２－３．母材（スラブ）
母材としては、前記のチタン複合材の内層の項で説明した工業用純チタンまたはチタン合金を用いる。特に、母材として直接鋳造スラブを用いるのがよい。直接鋳造スラブは、表面の少なくとも一部に溶融再凝固層を形成したものであってもよい。また、直接鋳造スラブの表面に溶融再凝固処理を実施する際に所定の元素を添加して、直接鋳造スラブの板厚中心部とは異なる化学組成を有する溶融再凝固層を形成したものであってもよい。 2-3. Base material (slab)
As the base material, the industrial pure titanium or titanium alloy described in the section of the inner layer of the titanium composite is used. In particular, it is preferable to use a direct casting slab as a base material. The direct cast slab may be one in which a melt resolidified layer is formed on at least a part of the surface. In addition, a predetermined element was added to the surface of the direct casting slab when the melt resolidification process was performed, and a melt resolidification layer having a chemical composition different from that of the center portion of the direct casting slab was formed. May be.
母材としては、前記のチタン複合材の内層の項で説明した工業用純チタンまたはチタン合金を用いる。特に、母材として直接鋳造スラブを用いるのがよい。直接鋳造スラブは、表面の少なくとも一部に溶融再凝固層を形成したものであってもよい。また、直接鋳造スラブの表面に溶融再凝固処理を実施する際に所定の元素を添加して、直接鋳造スラブの板厚中心部とは異なる化学組成を有する溶融再凝固層を形成したものであってもよい。 2-3. Base material (slab)
As the base material, the industrial pure titanium or titanium alloy described in the section of the inner layer of the titanium composite is used. In particular, it is preferable to use a direct casting slab as a base material. The direct cast slab may be one in which a melt resolidified layer is formed on at least a part of the surface. In addition, a predetermined element was added to the surface of the direct casting slab when the melt resolidification process was performed, and a melt resolidification layer having a chemical composition different from that of the center portion of the direct casting slab was formed. May be.
２－４．溶接部
スラブ６の圧延面に当たる表面に、合金元素を含有するチタン板７を貼り合わせた後、真空容器内で、少なくとも周囲を溶接部９により溶接することによって、スラブ６とチタン板７，８の間を真空で密閉し、外気と遮断し、圧延することによりスラブ６とチタン板７，８とを貼り合わせる。スラブ６にチタン板７，８を貼り合わせた後に接合する溶接部は、スラブ６とチタン板７，８の界面を大気から遮断するように、例えば、図３，４に示すように全周を溶接する。 2-4. After the titanium plate 7 containing an alloy element is bonded to the surface corresponding to the rolling surface of the weldedportion slab 6, the slab 6 and the titanium plates 7 and 8 are welded at least around the welded portion 9 in a vacuum vessel. The slab 6 and the titanium plates 7 and 8 are bonded together by sealing with a vacuum, blocking the outside air, and rolling. For example, as shown in FIGS. 3 and 4, the welded portion to be joined after the titanium plates 7 and 8 are bonded to the slab 6 is shielded from the atmosphere at the interface between the slab 6 and the titanium plates 7 and 8. Weld.
スラブ６の圧延面に当たる表面に、合金元素を含有するチタン板７を貼り合わせた後、真空容器内で、少なくとも周囲を溶接部９により溶接することによって、スラブ６とチタン板７，８の間を真空で密閉し、外気と遮断し、圧延することによりスラブ６とチタン板７，８とを貼り合わせる。スラブ６にチタン板７，８を貼り合わせた後に接合する溶接部は、スラブ６とチタン板７，８の界面を大気から遮断するように、例えば、図３，４に示すように全周を溶接する。 2-4. After the titanium plate 7 containing an alloy element is bonded to the surface corresponding to the rolling surface of the welded
チタンは活性な金属であるため、大気中に放置すると表面に強固な不動態皮膜を形成する。この表面部の酸化濃化層を除去することは不可能である。しかし、ステンレス等とは異なり、チタンには酸素が固溶し易いため、真空中で密閉されて外部からの酸素の供給が無い状態で加熱されると、表面の酸素は内部に拡散し固溶するため、表面に形成した不動態皮膜は消滅する。そのため、スラブ６とその表面のチタン板７，８とは、その間に介在物なども発生せずに、熱延クラッド法により完全に密着することができる。
Titanium is an active metal and forms a strong passive film on the surface when left in the atmosphere. It is impossible to remove the oxidized layer on the surface. However, unlike stainless steel, etc., oxygen easily dissolves in titanium. Therefore, when heated in a vacuum and sealed without external oxygen supply, oxygen on the surface diffuses into the solid solution. Therefore, the passive film formed on the surface disappears. Therefore, the slab 6 and the titanium plates 7 and 8 on the surface thereof can be completely adhered by the hot rolling cladding method without generating any inclusions between them.
さらに、スラブ６として鋳造ままのスラブを用いると、凝固時に生成した粗大な結晶粒に起因し、その後の熱間圧延工程で表面疵が発生してしまう。これに対し、本発明のようにスラブ６の圧延面にチタン板７，８を貼り合わせると、貼り合わせたチタン板７が微細な組織を有するために熱間圧延工程での表面疵も抑制できる。
Furthermore, when an as-cast slab is used as the slab 6, surface defects occur in the subsequent hot rolling process due to coarse crystal grains generated during solidification. On the other hand, when the titanium plates 7 and 8 are bonded to the rolled surface of the slab 6 as in the present invention, the bonded titanium plate 7 has a fine structure, so that surface defects in the hot rolling process can be suppressed. .
３．熱間圧延用チタン材の製造方法
３－１．母材の製造方法
熱間圧延用チタン材の母材は、通常、インゴットをブレークダウンによりスラブやビレット形状にした後、切削精整して製造される。また、近年ではインゴット製造時に直接熱延可能な矩形スラブを製造し、熱延に供されることもある。ブレークダウンにより製造された場合、ブレークダウンにより表面が比較的平坦になっているため、合金元素を含有する素材を比較的均一に散布し易く、合金相の元素分布を均一にしやすい。 3. 3. Method of manufacturing titanium material for hot rolling 3-1. Manufacturing method of base material A base material of a titanium material for hot rolling is usually manufactured by cutting and refining an ingot after making it into a slab or billet shape by breakdown. In recent years, rectangular slabs that can be hot-rolled directly at the time of ingot production are sometimes produced and used for hot-rolling. When manufactured by breakdown, since the surface is relatively flat by breakdown, it is easy to disperse the material containing the alloy element relatively uniformly, and it is easy to make the element distribution of the alloy phase uniform.
３－１．母材の製造方法
熱間圧延用チタン材の母材は、通常、インゴットをブレークダウンによりスラブやビレット形状にした後、切削精整して製造される。また、近年ではインゴット製造時に直接熱延可能な矩形スラブを製造し、熱延に供されることもある。ブレークダウンにより製造された場合、ブレークダウンにより表面が比較的平坦になっているため、合金元素を含有する素材を比較的均一に散布し易く、合金相の元素分布を均一にしやすい。 3. 3. Method of manufacturing titanium material for hot rolling 3-1. Manufacturing method of base material A base material of a titanium material for hot rolling is usually manufactured by cutting and refining an ingot after making it into a slab or billet shape by breakdown. In recent years, rectangular slabs that can be hot-rolled directly at the time of ingot production are sometimes produced and used for hot-rolling. When manufactured by breakdown, since the surface is relatively flat by breakdown, it is easy to disperse the material containing the alloy element relatively uniformly, and it is easy to make the element distribution of the alloy phase uniform.
一方、鋳造時に熱延用素材の形状に直接製造された鋳塊（直接鋳造スラブ）を母材として用いる場合、切削精整工程を省略できるため、より安価に製造することができる。また、鋳塊を製造後に、表面を切削精整してから用いれば、ブレークダウンを経て製造した場合同様の効果が期待できる。本発明においては、表層に安定的に合金層が形成すればよく、状況に合わせて適切な素材を選べばよい。
On the other hand, when an ingot directly manufactured in the shape of a hot-rolling material during casting (direct casting slab) is used as a base material, the cutting and refining process can be omitted, so that it can be manufactured at a lower cost. In addition, if the ingot is manufactured and then used after the surface is cut and refined, the same effect can be expected when it is manufactured through breakdown. In the present invention, an alloy layer may be stably formed on the surface layer, and an appropriate material may be selected according to the situation.
例えば、スラブを組み立て、周囲を溶接した後、７００～８５０℃に加熱し１０～３０％の接合圧延を行い、その後β域温度で３～１０時間加熱し母材成分を表層部に拡散させた後に、熱間圧延を行うことが好ましい。β域温度で熱間圧延を行うことによって、変形抵抗が低くなり圧延し易くなるからである。
For example, after assembling the slab and welding the surroundings, it is heated to 700 to 850 ° C. and subjected to 10-30% joint rolling, and then heated at the β-zone temperature for 3 to 10 hours to diffuse the base material components to the surface layer. It is preferable to perform hot rolling later. This is because by performing hot rolling at a β-region temperature, the deformation resistance becomes low and rolling becomes easy.
母材として用いる直接鋳造スラブは、表面の少なくとも一部に溶融再凝固層を形成したものであってもよい。また、直接鋳造スラブの表面に溶融再凝固処理を実施する際に所定の元素を添加して、直接鋳造スラブの板厚中心部とは異なる化学組成を有する溶融再凝固層を形成したものであってもよい。以下、溶融再凝固処理について詳しく説明する。
The direct cast slab used as the base material may be one in which a melt resolidification layer is formed on at least a part of the surface. In addition, a predetermined element was added to the surface of the direct casting slab when the melt resolidification process was performed, and a melt resolidification layer having a chemical composition different from that of the center portion of the direct casting slab was formed. May be. Hereinafter, the melt resolidification process will be described in detail.
図５～７は、いずれも溶融再凝固の方法を示す説明図である。熱間圧延用チタン材の母材表面を溶融再凝固させる方法としては、レーザー加熱、プラズマ加熱、誘導加熱、電子ビーム加熱などがあり、いずれかの方法で行えばよい。特に、特に電子ビーム加熱の場合、高真空中で行うため、溶融再凝固処理の際に、この層にボイド等を形成しても、真空であるため、後の圧延で圧着し無害化できる。
FIGS. 5 to 7 are explanatory diagrams showing the method of melt re-solidification. As a method for melting and resolidifying the surface of the base material of the titanium material for hot rolling, there are laser heating, plasma heating, induction heating, electron beam heating, etc., and any method may be used. In particular, especially in the case of electron beam heating, since it is performed in a high vacuum, even if a void or the like is formed in this layer during the melt resolidification treatment, it can be made harmless by pressure bonding in subsequent rolling because it is a vacuum.
さらに、エネルギー効率が高いことから大面積を処理しても深く溶融させることができるため、特にチタン複合材の製造に適している。真空中で溶融する場合の真空度は、３×１０－３Ｔｏｒｒ以下のより高い真空度であることが望ましい。また、熱間圧延用チタン材の表層を溶融再凝固する回数については、特に制限はない。ただし、回数が多くなるほど、処理時間が長くなりコスト増につながるため、１回ないし２回であることが望ましい。
Furthermore, since it is high in energy efficiency, it can be melted deeply even if a large area is processed, and is particularly suitable for the production of titanium composite materials. The degree of vacuum in the case of melting in a vacuum is desirably higher than 3 × 10 −3 Torr. Moreover, there is no restriction | limiting in particular about the frequency | count of melt-solidifying the surface layer of the titanium material for hot rolling. However, as the number of times increases, the processing time becomes longer and the cost increases.
表層の溶融再凝固法は、矩形のスラブの場合では図５に示しているように実施する。すなわち、矩形スラブ１０の外表面のうち、少なくとも熱間圧延工程での圧延面（熱延ロールに接する面）となる幅広な２面１０Ａ，１０Ｂについて、電子ビームを照射して、その面における表面層のみを溶融させる。ここでは先ずその２面１０Ａ，１０Ｂのうちの一方の面１０Ａについて実施するものとする。
The melt resolidification method of the surface layer is carried out as shown in FIG. 5 in the case of a rectangular slab. That is, among the outer surfaces of the rectangular slab 10, at least two wide surfaces 10A and 10B that become the rolling surfaces (surfaces in contact with the hot rolling roll) in the hot rolling process are irradiated with an electron beam, and the surfaces on the surfaces are irradiated. Only melt the layer. Here, it is assumed that the surface 10A is one of the two surfaces 10A and 10B.
ここで、図５に示しているように、矩形鋳片１０の面１０Ａに対する一基の電子ビーム照射ガン１２による電子ビームの照射領域１４の面積は、照射すべき面１０Ａの全面積と比較して格段に小さいのが通常である、そこで、実際には、電子ビーム照射ガン１２を連続的に移動させながら、または、矩形鋳片１０を連続的に移動させながら、電子ビーム照射を行なうのが通常である。この照射領域は、電子ビームの焦点を調整することによって、あるいは電磁レンズを使用して小ビームを高周波数で振動（オシレーション Ｏｓｃｉｌｌａｔｉｏｎ）させてビーム束を形成させることによって、その形状や面積を調整することができる。
Here, as shown in FIG. 5, the area of the electron beam irradiation region 14 by the single electron beam irradiation gun 12 on the surface 10A of the rectangular slab 10 is compared with the total area of the surface 10A to be irradiated. The electron beam irradiation is actually performed while continuously moving the electron beam irradiation gun 12 or continuously moving the rectangular slab 10. It is normal. The shape and area of this irradiation area can be adjusted by adjusting the focus of the electron beam or by using an electromagnetic lens to oscillate a small beam at a high frequency (oscillation Oscillation) to form a beam bundle. can do.
そして、図５中の矢印Ａで示しているように、電子ビーム照射ガン１２を連続的に移動させるものとして、以下の説明を進める。なお電子ビーム照射ガンの移動方向は特に限定されないが、一般には矩形鋳片１０の長さ方向（通常は鋳造方向Ｄ）または幅方向（通常は鋳造方向Ｄと垂直な方向）に沿って連続的に移動させ、前記照射領域１４の幅Ｗ（円形ビームまたはビーム束の場合は、直径Ｗ）で連続的に帯状に照射する。さらにその隣の未照射の帯状領域について逆方向（もしくは同方向）に照射ガン１２を連続的に移動させながら帯状に電子ビーム照射を行なう。また場合によっては複数の照射ガンを用いて、同時に複数の領域について同時に電子ビーム照射を行なっても良い。図５では、矩形鋳片１０の長さ方向（通常は鋳造方向Ｄ）に沿って矩形ビームを連続的に移動させる場合を示している。
Then, as indicated by an arrow A in FIG. 5, the following description will be made assuming that the electron beam irradiation gun 12 is continuously moved. Although the moving direction of the electron beam irradiation gun is not particularly limited, it is generally continuous along the length direction (usually the casting direction D) or the width direction (usually the direction perpendicular to the casting direction D) of the rectangular slab 10. Then, the irradiation region 14 is continuously irradiated in a band shape with a width W (in the case of a circular beam or beam bundle, a diameter W). Further, the electron beam irradiation is performed in a belt shape while continuously moving the irradiation gun 12 in the reverse direction (or the same direction) in the adjacent unirradiated belt region. In some cases, a plurality of irradiation guns may be used to simultaneously perform electron beam irradiation on a plurality of regions. In FIG. 5, the case where a rectangular beam is continuously moved along the length direction (usually casting direction D) of the rectangular slab 10 is shown.
このような表層加熱処理工程によって矩形チタン鋳片１０の表面（面１０Ａ）に電子ビームを照射して、その表面を溶融するように加熱すれば、図６の中央左寄りに示すように、矩形チタン鋳片１０の面１０Ａの表面層が、入熱量に応じた深さだけ最大溶融される。しかしながら、電子ビームの照射方向に対して垂直方向からの深さは図７に示すように一定ではなく、電子ビーム照射の中央部が最も深さが大きくなり、帯状の端部に行くほどその厚みが減少する、下に凸の湾曲形状となる。
If the surface (surface 10A) of the rectangular titanium cast piece 10 is irradiated with an electron beam by such a surface heat treatment step and heated to melt the surface, the rectangular titanium as shown in the left side of the center of FIG. The surface layer of the surface 10A of the slab 10 is melted at the maximum by a depth corresponding to the heat input. However, the depth from the direction perpendicular to the irradiation direction of the electron beam is not constant as shown in FIG. 7, and the depth becomes the largest at the central part of the electron beam irradiation, and the thickness increases toward the strip-shaped end part. Decreases, resulting in a downwardly convex curved shape.
またその溶融層１６よりも鋳片内部側の領域も、電子ビーム照射による熱影響によって温度上昇し、純チタンのβ変態点以上の温度となった部分（熱影響層＝ＨＡＺ層）がβ相に変態する。このように表層加熱処理工程での電子ビーム照射による熱影響によってβ相に変態した領域も、溶融層１６の形状と同様に下に凸の湾曲形状となる。
The region inside the slab from the molten layer 16 also rises in temperature due to the heat effect of electron beam irradiation, and the portion where the temperature is higher than the β transformation point of pure titanium (heat affected layer = HAZ layer) is the β phase. To metamorphosis. In this way, the region transformed into the β phase by the heat effect of the electron beam irradiation in the surface heat treatment step also has a downwardly curved shape similar to the shape of the molten layer 16.
表層を、目的とする合金元素から成る素材とともに溶融再凝固を行うことにより、熱間圧延用素材表層を合金化し、母材とは異なる化学組成の合金層を形成することができる。この際に用いる素材としては、粉末、チップ、ワイヤー、薄膜、切り粉、メッシュのうちの１種以上を用いればよい。溶融前に配置する材料の成分および量については、素材表面とともに溶融し凝固した後の元素濃化領域の成分が目標成分となるように定める。
The surface layer is melted and re-solidified with a material composed of the target alloy element, whereby the surface layer of the material for hot rolling can be alloyed to form an alloy layer having a chemical composition different from that of the base material. As a material used in this case, one or more of powder, chip, wire, thin film, cutting powder, and mesh may be used. The component and amount of the material to be arranged before melting are determined so that the component in the element concentration region after melting and solidifying together with the material surface becomes the target component.
ただし、この添加する素材が大きすぎると、合金成分の偏析の原因となる。そして、合金成分の偏析が存在すると、所望の性能を十分に発揮できないか、劣化が早まってしまう。このため、チタン母材表面の被加熱部位が溶融状態にあるうちに、合金素材が溶融し終えるサイズにすることが重要である。また、特定の時間における溶融部の形状および広さを考慮した上で、上記合金素材をチタン母材表面に均等に配置しておくことが重要である。しかしながら、電子ビームを使って照射位置を連続的に移動させる場合には、溶融部は溶融したチタンおよび合金とともに連続的に移動しながら攪拌されるため、合金素材は必ずしも連続的に配置しておく必要はない。そのほか、チタンの融点よりも極端に高い融点を有する合金素材の使用は避けなければならないことは当然である。
However, if this added material is too large, it will cause segregation of alloy components. And when the segregation of an alloy component exists, desired performance cannot fully be exhibited, or deterioration will be accelerated. For this reason, it is important to make the size of the alloy material completely melted while the heated portion on the surface of the titanium base material is in a molten state. In addition, it is important that the alloy material is evenly arranged on the surface of the titanium base material in consideration of the shape and size of the melted part at a specific time. However, when the irradiation position is continuously moved using the electron beam, the molten part is stirred while moving continuously with the molten titanium and the alloy, so that the alloy material is always arranged continuously. There is no need. In addition, it is natural that the use of an alloy material having a melting point extremely higher than that of titanium must be avoided.
溶融再凝固処理後は、１００℃以上５００℃未満の温度で１時間以上保持するのがよい。溶融再凝固後、急激に冷却すると凝固時の歪で表層部に微細な割れが発生するおそれがある。その後の熱延工程や冷延工程において、この微細な割れが起点となって、表層の剥離が発生する、部分的に合金層が薄い部位が発生するなど、特性が劣化するおそれがある。また、微細な割れによって内部が酸化すると、酸洗工程で除去する必要があり、合金層の厚さをさらに減少させる。上記の温度で保持することで表面の微細な割れを抑制できる。また、この温度であれば大気中で保持しても大気酸化は殆どしない。
After the melt resolidification treatment, it is preferable to hold at a temperature of 100 ° C. or higher and lower than 500 ° C. for 1 hour or longer. If it is cooled rapidly after melting and resolidification, fine cracks may occur in the surface layer due to strain during solidification. In the subsequent hot rolling process and cold rolling process, the fine cracks may be the starting point, and the surface layer may be peeled off, or the part of the alloy layer may be partially thin. Further, if the inside is oxidized due to fine cracks, it is necessary to remove in the pickling process, and the thickness of the alloy layer is further reduced. By maintaining at the above temperature, fine cracks on the surface can be suppressed. At this temperature, atmospheric oxidation hardly occurs even if the temperature is maintained.
溶融再凝固処理によって形成した表層部を備える母材表面に所定の合金成分を含有するチタン板を貼り付けることにより熱間圧延用チタン材を製造することができる。
３－２．熱延クラッド法
熱間圧延用チタン材は、熱延クラッド法により、予め、周囲を溶接したスラブ６とチタン板７，８を接合するのがよい。 A titanium material for hot rolling can be manufactured by attaching a titanium plate containing a predetermined alloy component to the surface of a base material provided with a surface layer portion formed by melt resolidification treatment.
3-2. Hot Rolled Clad Method The titanium material for hot rolling is preferably bonded to theslab 6 and the titanium plates 7 and 8 which are welded in advance by the hot rolled clad method.
３－２．熱延クラッド法
熱間圧延用チタン材は、熱延クラッド法により、予め、周囲を溶接したスラブ６とチタン板７，８を接合するのがよい。 A titanium material for hot rolling can be manufactured by attaching a titanium plate containing a predetermined alloy component to the surface of a base material provided with a surface layer portion formed by melt resolidification treatment.
3-2. Hot Rolled Clad Method The titanium material for hot rolling is preferably bonded to the
図３，４に示すように、スラブ６の表層に特性を発現する合金元素を含有したチタン板７，８を貼り合わせた後、熱延クラッド法により接合させることによりチタン複合材の表層を合金化する。すなわち、スラブ６の圧延面に当たる表面に、合金元素を含有するチタン板７を貼り合わせた後、好ましくは真空容器内で、少なくとも周囲を溶接部９により溶接することによって、スラブ６とチタン板７の間を真空で密閉し、圧延することによりスラブ６とチタン板７とを貼り合わせる。スラブ６にチタン板７を貼り合わせる溶接は、スラブ６とチタン板７の間に大気が侵入しないよう、例えば、図３，４に示すように全周を溶接する。
As shown in FIGS. 3 and 4, the titanium plates 7 and 8 containing alloy elements that express characteristics are bonded to the surface layer of the slab 6, and then bonded by hot rolling cladding to alloy the surface layer of the titanium composite material. Turn into. That is, after the titanium plate 7 containing the alloy element is bonded to the surface corresponding to the rolling surface of the slab 6, the slab 6 and the titanium plate 7 are preferably welded at least around the welded portion 9 in a vacuum vessel. The space between the slab 6 and the titanium plate 7 is bonded together by vacuum sealing and rolling. In welding for bonding the titanium plate 7 to the slab 6, for example, as shown in FIGS. 3 and 4, the entire circumference is welded so that air does not enter between the slab 6 and the titanium plate 7.
チタンは活性な金属であるため、大気中に放置すると表面に強固な不動態皮膜を形成する。この表面部の酸化濃化層を除去することは不可能である。しかし、ステンレス等とは異なり、チタンには酸素が固溶し易いため、真空中で密閉されて外部からの酸素の供給が無い状態で加熱されると、表面の酸素は内部に拡散し固溶するため、表面に形成した不動態皮膜は消滅する。そのため、スラブ６とその表面のチタン板７とは、その間に介在物なども発生せずに、熱延クラッド法により完全に密着することができる。
Titanium is an active metal and forms a strong passive film on the surface when left in the atmosphere. It is impossible to remove the oxidized layer on the surface. However, unlike stainless steel, etc., oxygen easily dissolves in titanium. Therefore, when heated in a vacuum and sealed without external oxygen supply, oxygen on the surface diffuses into the solid solution. Therefore, the passive film formed on the surface disappears. For this reason, the slab 6 and the titanium plate 7 on the surface thereof can be completely adhered by the hot rolling cladding method without generating any inclusions between them.
さらに、スラブ６として鋳造ままのスラブを用いると、凝固時に生成した粗大な結晶粒に起因し、その後の熱間圧延工程で表面疵が発生してしまう。これに対し、本発明のようにスラブ６の圧延面にチタン板７を貼り合わせると、貼り合わせたチタン板７が微細な組織を有するために熱間圧延工程での表面疵も抑制できる。
Furthermore, when an as-cast slab is used as the slab 6, surface defects occur in the subsequent hot rolling process due to coarse crystal grains generated during solidification. On the other hand, when the titanium plate 7 is bonded to the rolled surface of the slab 6 as in the present invention, the bonded titanium plate 7 has a fine structure, so that surface defects in the hot rolling process can be suppressed.
図３に示すように、スラブ６の片面たけでなく両面にチタン板７を貼り合わせてもよい。これにより、上述したように熱間圧延工程での熱延疵の発生を抑制できる。熱間圧延においては、通常、スラブ６に圧下されることによって、スラブ６の側面の少なくとも一部が熱延板の表面側に回り込む。そのため、スラブ６の側面の表層の組織が粗大であったり、多数の欠陥が存在していたりすると、熱延板の幅方向の両端近くの表面に表面疵が発生する可能性がある。このため、図４に示すように、熱間圧延時のエッジ側となるスラブ６の側面についても、圧延面と同様に同一規格のチタン板８を貼り合わせて溶接するのがよい。これにより、熱延板の幅方向の両端近くの表面における表面疵の発生を有効に防止できる。この溶接は、真空中で行うのが好ましい。
As shown in FIG. 3, titanium plates 7 may be bonded to both sides of the slab 6 instead of just one side. Thereby, generation | occurrence | production of the hot rolling in a hot rolling process can be suppressed as mentioned above. In hot rolling, at least a part of the side surface of the slab 6 usually wraps around the surface side of the hot-rolled sheet by being rolled down by the slab 6. Therefore, if the structure of the surface layer on the side surface of the slab 6 is coarse or a large number of defects exist, surface flaws may occur on the surface near both ends in the width direction of the hot-rolled sheet. For this reason, as shown in FIG. 4, the same standard titanium plate 8 is preferably bonded and welded to the side surface of the slab 6 on the edge side during hot rolling as well as the rolled surface. Thereby, generation | occurrence | production of the surface flaw in the surface near the both ends of the width direction of a hot rolled sheet can be prevented effectively. This welding is preferably performed in a vacuum.
なお、熱間圧延時にスラブ６の側面が回り込む量は、製造方法により異なるが、通常は２０～３０ｍｍ程度であるため、スラブ６の側面全面にチタン板８を貼り付ける必要はなく、製造方法に則した回り込み量に相当する部分にのみチタン板８を貼り付ければよい。熱間圧延以降に高温長時間焼鈍を行うことにより、母材由来成分をチタン複合材の内部に含有させることができる。例えば７００～９００℃で３０時間の熱処理が例示される。
The amount of the side surface of the slab 6 that wraps around during hot rolling varies depending on the manufacturing method, but is usually about 20 to 30 mm. Therefore, it is not necessary to attach the titanium plate 8 to the entire side surface of the slab 6, and the manufacturing method is not limited. It is only necessary to attach the titanium plate 8 only to the portion corresponding to the sneak amount. By performing high-temperature long-time annealing after hot rolling, the base material-derived component can be contained in the titanium composite material. For example, heat treatment at 700 to 900 ° C. for 30 hours is exemplified.
スラブ６とチタン板７，８を真空中で溶接する方法は、電子ビーム溶接やプラズマ溶接などがある。特に電子ビーム溶接は、高真空下で実施できることから、スラブ６とチタン板７，８との間を高真空にすることができるため、望ましい。チタン板７，８を真空中で溶接する場合の真空度は３×１０-３Ｔｏｒｒ以下のより高い真空度であることが望ましい。
Methods for welding the slab 6 and the titanium plates 7 and 8 in vacuum include electron beam welding and plasma welding. In particular, since the electron beam welding can be performed under a high vacuum, the space between the slab 6 and the titanium plates 7 and 8 can be made a high vacuum, which is desirable. The degree of vacuum when the titanium plates 7 and 8 are welded in a vacuum is desirably a higher degree of vacuum of 3 × 10 −3 Torr or less.
なお、スラブ６とチタン板７との溶接は、必ずしも真空容器内で行う必要はなく、例えば、チタン板７の内部に真空吸引用孔を設けておき、チタン板７をスラブ６と重ね合わせた後に、真空吸引孔を用いてスラブ６とチタン板７との間を真空引きしながらスラブ６とチタン板７とを溶接し、溶接後に真空吸引孔を封止してもよい。
The slab 6 and the titanium plate 7 are not necessarily welded in a vacuum vessel. For example, a vacuum suction hole is provided in the titanium plate 7 and the titanium plate 7 is overlapped with the slab 6. Later, the slab 6 and the titanium plate 7 may be welded while evacuating the slab 6 and the titanium plate 7 using a vacuum suction hole, and the vacuum suction hole may be sealed after welding.
クラッドとしてスラブ６の表面に目的とする合金元素を有するチタン板７，８を使用し、熱延クラッドによりチタン複合材１，２の表層に合金層を形成する場合、表層の厚みや化学成分は貼り合わせる前のチタン板７，８の厚みや合金元素の分布に依存する。もちろん、チタン板７，８を製造する際には、最終的に必要とする強度や延性を得るために、真空雰囲気などで焼鈍処理が施されるため、界面での拡散を生じ、界面近傍では深さ方向に濃度勾配を生じる。
When titanium plates 7 and 8 having a target alloy element are used as the clad on the surface of the slab 6 and an alloy layer is formed on the surface of the titanium composites 1 and 2 by hot rolling clad, the thickness and chemical composition of the surface layer are as follows: It depends on the thickness of the titanium plates 7 and 8 before bonding and the distribution of alloy elements. Of course, when the titanium plates 7 and 8 are manufactured, the annealing treatment is performed in a vacuum atmosphere or the like in order to obtain the finally required strength and ductility. A concentration gradient is generated in the depth direction.
しかしながら、最終焼鈍工程で生じる元素の拡散距離は数μｍ程度であり、合金層の厚み全体が拡散するわけではなく、特に特性発現に重要となる表層の近傍の合金元素の濃度には影響しない。
However, the diffusion distance of the element generated in the final annealing step is about several μm, and the entire thickness of the alloy layer does not diffuse, and does not affect the concentration of the alloy element in the vicinity of the surface layer, which is particularly important for property development.
このため、チタン板７，８全体での合金成分の均一性が特性の安定的な発現につながる。熱延クラッドの場合、製品として製造されたチタン板７，８を使用することが可能であるため、板厚精度はもちろんのこと、合金成分の偏析をコントロールし易く、製造後に均一な厚みかつ化学成分を有する表層を備えるチタン複合材１，２を製造することが可能であり、安定した特性を発現できる。
For this reason, the uniformity of the alloy components in the entire titanium plates 7 and 8 leads to stable expression of the characteristics. In the case of hot-rolled clad, it is possible to use titanium plates 7 and 8 manufactured as products, so it is easy to control the segregation of alloy components as well as the plate thickness accuracy, and have a uniform thickness and chemical properties after manufacturing. Titanium composite materials 1 and 2 having a surface layer having components can be produced, and stable characteristics can be expressed.
また、上述したように、チタン複合材１，２の表層と内層５との間に介在物が発生しないことから、密着性の他、割れや疲労などの起点になることもない。
Further, as described above, since no inclusions are generated between the surface layer and the inner layer 5 of the titanium composites 1 and 2, there is no starting point such as cracking or fatigue in addition to adhesion.
３．チタン複合材の製造方法
スラブ表面にチタン板を貼り付けることにより形成した合金層を最終製品として残存させることが重要であり、スケールロスや表面疵による表面層の除去を可能な限り抑制する必要がある。具体的には、下記のような熱間圧延工程上の工夫を、生産に使用する設備の特性や能力を考慮した上で最適化し適宜採用することにより、達成される。 3. Manufacturing method of titanium composite It is important to leave the alloy layer formed by sticking a titanium plate on the slab surface as the final product, and it is necessary to suppress the removal of the surface layer due to scale loss and surface flaws as much as possible. is there. Specifically, this is achieved by optimizing and appropriately adopting the following devices in the hot rolling process in consideration of the characteristics and capabilities of the equipment used for production.
スラブ表面にチタン板を貼り付けることにより形成した合金層を最終製品として残存させることが重要であり、スケールロスや表面疵による表面層の除去を可能な限り抑制する必要がある。具体的には、下記のような熱間圧延工程上の工夫を、生産に使用する設備の特性や能力を考慮した上で最適化し適宜採用することにより、達成される。 3. Manufacturing method of titanium composite It is important to leave the alloy layer formed by sticking a titanium plate on the slab surface as the final product, and it is necessary to suppress the removal of the surface layer due to scale loss and surface flaws as much as possible. is there. Specifically, this is achieved by optimizing and appropriately adopting the following devices in the hot rolling process in consideration of the characteristics and capabilities of the equipment used for production.
４－１．加熱工程
熱間圧延用素材を加熱する際には低温短時間加熱を行うことによりスケールロスを低く抑制できるが、チタン材は熱伝導が小さくスラブ内部が低温状態で熱間圧延を行うと内部で割れが発生し易くなる欠点もあり、使用する加熱炉の性能や特性に合わせてスケール発生を最小限に抑制するように最適化する。 4-1. Heating process When heating the raw material for hot rolling, scale loss can be suppressed by heating at low temperature for a short time, but the titanium material has low heat conduction, and if the inside of the slab is hot rolled at a low temperature, There is also a drawback that cracks are likely to occur, and optimization is performed to minimize the generation of scales according to the performance and characteristics of the heating furnace used.
熱間圧延用素材を加熱する際には低温短時間加熱を行うことによりスケールロスを低く抑制できるが、チタン材は熱伝導が小さくスラブ内部が低温状態で熱間圧延を行うと内部で割れが発生し易くなる欠点もあり、使用する加熱炉の性能や特性に合わせてスケール発生を最小限に抑制するように最適化する。 4-1. Heating process When heating the raw material for hot rolling, scale loss can be suppressed by heating at low temperature for a short time, but the titanium material has low heat conduction, and if the inside of the slab is hot rolled at a low temperature, There is also a drawback that cracks are likely to occur, and optimization is performed to minimize the generation of scales according to the performance and characteristics of the heating furnace used.
４－２．熱間圧延工程
熱間圧延工程においても、表面温度が高すぎると通板時にスケールが多く生成し、スケールロスが大きくなる。一方で、低すぎると、スケールロスは小さくなるが、表面疵が発生し易くなるため、後工程の酸洗で除去する必要があり、表面疵が抑制できる温度範囲で熱間圧延することが望ましい。そのため、最適温度域で圧延することが望ましい。また、圧延中にチタン材の表面温度が低下するため、圧延中のロール冷却は最小限とし、チタン材の表面温度の低下を抑制することが望ましい。 4-2. Hot rolling process Also in the hot rolling process, if the surface temperature is too high, a large amount of scale is generated during sheet passing, and the scale loss increases. On the other hand, if it is too low, the scale loss is reduced, but surface flaws are likely to occur. Therefore, it is necessary to remove by surface pickling, and it is desirable to perform hot rolling in a temperature range in which surface flaws can be suppressed. . Therefore, it is desirable to perform rolling in the optimum temperature range. In addition, since the surface temperature of the titanium material decreases during rolling, it is desirable to minimize roll cooling during rolling and suppress the decrease in the surface temperature of the titanium material.
熱間圧延工程においても、表面温度が高すぎると通板時にスケールが多く生成し、スケールロスが大きくなる。一方で、低すぎると、スケールロスは小さくなるが、表面疵が発生し易くなるため、後工程の酸洗で除去する必要があり、表面疵が抑制できる温度範囲で熱間圧延することが望ましい。そのため、最適温度域で圧延することが望ましい。また、圧延中にチタン材の表面温度が低下するため、圧延中のロール冷却は最小限とし、チタン材の表面温度の低下を抑制することが望ましい。 4-2. Hot rolling process Also in the hot rolling process, if the surface temperature is too high, a large amount of scale is generated during sheet passing, and the scale loss increases. On the other hand, if it is too low, the scale loss is reduced, but surface flaws are likely to occur. Therefore, it is necessary to remove by surface pickling, and it is desirable to perform hot rolling in a temperature range in which surface flaws can be suppressed. . Therefore, it is desirable to perform rolling in the optimum temperature range. In addition, since the surface temperature of the titanium material decreases during rolling, it is desirable to minimize roll cooling during rolling and suppress the decrease in the surface temperature of the titanium material.
４－３．酸洗工程
熱間圧延された板には、表面に酸化層があるため、その後の工程で酸化層を除去するデスケーリングの工程がある。チタンでは主に、ショットブラスト後に、硝ふっ酸溶液による酸洗で酸化層を除去するのが一般的である。また、場合によっては酸洗後に砥石研磨により表面を研削する場合もある。デスケーリング後に、熱間圧延用チタン材の母材および表層部に由来する、内層および表層からなる、２層または３層構造となっていればよい。 4-3. Pickling process Since the hot-rolled plate has an oxide layer on its surface, there is a descaling process for removing the oxide layer in the subsequent process. In titanium, after shot blasting, the oxide layer is generally removed by pickling with a nitric hydrofluoric acid solution. In some cases, the surface may be ground by grinding with a grindstone after pickling. After descaling, a two-layer or three-layer structure including an inner layer and a surface layer derived from the base material and the surface layer portion of the titanium material for hot rolling may be used.
熱間圧延された板には、表面に酸化層があるため、その後の工程で酸化層を除去するデスケーリングの工程がある。チタンでは主に、ショットブラスト後に、硝ふっ酸溶液による酸洗で酸化層を除去するのが一般的である。また、場合によっては酸洗後に砥石研磨により表面を研削する場合もある。デスケーリング後に、熱間圧延用チタン材の母材および表層部に由来する、内層および表層からなる、２層または３層構造となっていればよい。 4-3. Pickling process Since the hot-rolled plate has an oxide layer on its surface, there is a descaling process for removing the oxide layer in the subsequent process. In titanium, after shot blasting, the oxide layer is generally removed by pickling with a nitric hydrofluoric acid solution. In some cases, the surface may be ground by grinding with a grindstone after pickling. After descaling, a two-layer or three-layer structure including an inner layer and a surface layer derived from the base material and the surface layer portion of the titanium material for hot rolling may be used.
熱間圧延工程で生成したスケールは厚いため、通常は酸洗処理の前処理としてショットブラスト処理を行い表面のスケールの一部を除去すると同時に、表面にクラックを形成させ、その後の酸洗工程で液をクラックに浸透させ、母材の一部も含めて除去している。このとき、母材表面にクラックを生じさせないに弱いブラスト処理を行うことが重要であり、チタン材表面の化学成分に応じて最適なブラスト条件を選択する必要がある。具体的には、例えば適正な投射材の選択や投射速度（エンペラーの回転速度で調整可能）を最適化することによって、母材にクラックが生じない条件を選択する。これらの条件の最適化は、スラブ表面に貼り付けたチタン板の特性によって異なるため、予め最適条件をそれぞれ決めておけばよい。
Since the scale generated in the hot rolling process is thick, usually a shot blast treatment is performed as a pretreatment for the pickling treatment to remove a part of the scale on the surface, and at the same time, cracks are formed on the surface, and in the subsequent pickling step The liquid penetrates into the cracks and removes part of the base material. At this time, it is important to perform weak blasting without causing cracks on the surface of the base material, and it is necessary to select optimum blasting conditions according to the chemical components on the surface of the titanium material. Specifically, for example, by selecting an appropriate projecting material and optimizing the projecting speed (adjustable by the rotation speed of the emperor), a condition that does not cause a crack in the base material is selected. Since optimization of these conditions differs depending on the characteristics of the titanium plate attached to the slab surface, the optimum conditions may be determined in advance.
以下、実施例によって本発明をより具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples.
本発明を、実施例を参照しながら、より具体的に説明する。
板厚６０ｍｍ、幅１００ｍｍ、長さ１２０ｍｍの工業用純チタンＪＩＳ２種からなるスラブの上下面に、板厚３ｍｍのチタン合金板を、３×１０-３Ｔｏｒｒ以下の真空雰囲気で電子ビーム溶接により貼り合わせた。その後、８５０℃に加熱し、板厚４．８～５．０ｍｍまで熱延した。次いで、真空雰囲気で、６００～６５０℃、４～１０時間の焼鈍を施した。さらに、ショットブラスト、酸洗を行い、スケール層を除去した。 The present invention will be described more specifically with reference to examples.
A titanium alloy plate with a thickness of 3 mm is attached to the upper and lower surfaces of a slab made of two types of industrial pure titanium JIS with a thickness of 60 mm, a width of 100 mm, and a length of 120 mm by electron beam welding in a vacuum atmosphere of 3 × 10 −3 Torr or less. Combined. Thereafter, it was heated to 850 ° C. and hot rolled to a plate thickness of 4.8 to 5.0 mm. Next, annealing was performed in a vacuum atmosphere at 600 to 650 ° C. for 4 to 10 hours. Furthermore, shot blasting and pickling were performed to remove the scale layer.
板厚６０ｍｍ、幅１００ｍｍ、長さ１２０ｍｍの工業用純チタンＪＩＳ２種からなるスラブの上下面に、板厚３ｍｍのチタン合金板を、３×１０-３Ｔｏｒｒ以下の真空雰囲気で電子ビーム溶接により貼り合わせた。その後、８５０℃に加熱し、板厚４．８～５．０ｍｍまで熱延した。次いで、真空雰囲気で、６００～６５０℃、４～１０時間の焼鈍を施した。さらに、ショットブラスト、酸洗を行い、スケール層を除去した。 The present invention will be described more specifically with reference to examples.
A titanium alloy plate with a thickness of 3 mm is attached to the upper and lower surfaces of a slab made of two types of industrial pure titanium JIS with a thickness of 60 mm, a width of 100 mm, and a length of 120 mm by electron beam welding in a vacuum atmosphere of 3 × 10 −3 Torr or less. Combined. Thereafter, it was heated to 850 ° C. and hot rolled to a plate thickness of 4.8 to 5.0 mm. Next, annealing was performed in a vacuum atmosphere at 600 to 650 ° C. for 4 to 10 hours. Furthermore, shot blasting and pickling were performed to remove the scale layer.
本発明例として、上述した熱延クラッドにより表層３，４がＴｉ合金からなるとともに内部５が工業用純チタンＪＩＳ２種からなる、図２に示すチタン複合板２を使用した。比較例として表層３，４を有さない工業用純チタンＪＩＳ２種材を用いた。板厚はどちらも４．８～５ｍｍである。
As an example of the present invention, the titanium composite plate 2 shown in FIG. 2 in which the surface layers 3 and 4 are made of a Ti alloy and the inside 5 is made of industrial pure titanium JIS type 2 by the above-described hot-rolled cladding was used. As a comparative example, an industrial pure titanium JIS type 2 material having no surface layers 3 and 4 was used. Both plate thicknesses are 4.8-5 mm.
本発明例のチタン複合板２および比較例のチタン板を、水素吸収環境である１体積％Ｈ２＋９９％Ａｒ雰囲気で４００～５００℃、５時間暴露した。
The titanium composite plate 2 of the present invention example and the titanium plate of the comparative example were exposed at 400 to 500 ° C. for 5 hours in a 1% by volume H 2 + 99% Ar atmosphere as a hydrogen absorption environment.
本発明例のチタン複合板２および比較例のチタン板から、４．８～５ｍｍ×１０ｍｍ×５５ｍｍ、２ｍｍＶノッチの衝撃試験片をノッチの方向を板厚貫通方向として作製した。そして、シャルピー衝撃試験で測定した衝撃吸収エネルギーを試験片破断部の断面積で割ることにより衝撃値を算出し、その値で水素脆化特性を評価した。
From the titanium composite plate 2 of the present invention example and the titanium plate of the comparative example, an impact test piece of 4.8 to 5 mm × 10 mm × 55 mm and 2 mm V notch was produced with the notch direction as the plate thickness penetration direction. Then, an impact value was calculated by dividing the impact absorption energy measured in the Charpy impact test by the cross-sectional area of the test piece fracture portion, and the hydrogen embrittlement characteristics were evaluated based on the value.
また、製造したチタン複合板を、断面観察できるように樹脂に埋め込み、研磨・腐食したのちに、光学顕微鏡にて観察して、表層の厚さを測定した。この測定した表層の厚さをチタン複合材の全厚で除して、表層占有率として算出した。本実施例の表層占有率は、３～５％の範囲であった。
The manufactured titanium composite plate was embedded in a resin so that the cross section could be observed, polished and corroded, and then observed with an optical microscope to measure the thickness of the surface layer. The measured thickness of the surface layer was divided by the total thickness of the titanium composite material to calculate the surface layer occupation rate. The surface layer occupation ratio in this example was in the range of 3 to 5%.
表１に、表層３，４を有さない通常の工業用純チタンに関して、暴露条件、水素濃度、衝撃吸収エネルギーを示す。４５０℃×以上で暴露した場合、衝撃吸収エネルギーを試験片断面積で割った衝撃値は、２．０×１０２Ｊ／ｃｍ２未満まで低下した。水素濃度が充分に低い場合は２．７×１０２Ｊ／ｃｍ２であり、２０％以上低下している。このように、水素濃度が充分に低い場合の衝撃値から２０％以上低下した場合を、水素脆化を生じたと判定した。
Table 1 shows the exposure conditions, hydrogen concentration, and impact absorption energy for ordinary industrial pure titanium having no surface layers 3 and 4. When exposed at 450 ° C. × or higher, the impact value obtained by dividing the impact absorption energy by the cross-sectional area of the specimen decreased to less than 2.0 × 10 2 J / cm 2 . When the hydrogen concentration is sufficiently low, it is 2.7 × 10 2 J / cm 2, which is a decrease of 20% or more. As described above, it was determined that hydrogen embrittlement occurred when the impact value was reduced by 20% or more from the impact value when the hydrogen concentration was sufficiently low.
次に、表層３，４がＴｉ合金からなるチタン複合板２の本発明例を説明する。試験結果を表２にまとめて示す。表２における表層部の元素濃度は、ＥＰＭＡを用いて線分析を行い、表面から合金層の下端までの範囲を平均した結果である。また、水素環境下での暴露条件は、すべて５００℃、５時間であり、表２のＮｏ．３に相当する。
Next, an example of the present invention of the titanium composite plate 2 whose surface layers 3 and 4 are made of a Ti alloy will be described. The test results are summarized in Table 2. The element concentration in the surface layer portion in Table 2 is a result of performing line analysis using EPMA and averaging the range from the surface to the lower end of the alloy layer. The exposure conditions under a hydrogen environment are all 500 ° C. for 5 hours. It corresponds to 3.
Ｎｏ．１～５は、表層３，４のＴｉ合金がＭｏを単独で含有するものであり、Ｎｏ．６～９は表層３，４のＴｉ合金はＶを単独で含有するものであり、Ｎｏ．１０～１５は表層３，４のＴｉ合金がＭｏ、ＶおよびＮｂの２種以上を複合して含有するものである。
No. In Nos. 1 to 5, the Ti alloys of the surface layers 3 and 4 contain Mo alone. In Nos. 6 to 9, Ti alloys of the surface layers 3 and 4 contain V alone. In Nos. 10 to 15, the Ti alloys of the surface layers 3 and 4 contain a combination of two or more of Mo, V and Nb.
表２に示すように、本発明例であるＮｏ．２～４，７～１４の衝撃値は２．４～２．８×１０２Ｊ／ｃｍ２と高く、優れた耐水素脆化特性を有することがわかる。
As shown in Table 2, the present invention is No. The impact values of 2 to 4 and 7 to 14 are as high as 2.4 to 2.8 × 10 2 J / cm 2 , indicating that they have excellent hydrogen embrittlement resistance.
これに対し、比較例であるＮｏ．１は、Ｍｏ当量が４と低いために衝撃値が１．４Ｊ×１０２／ｃｍ２と小さい。
On the other hand, No. which is a comparative example. 1 has an impact value as small as 1.4 J × 10 2 / cm 2 because the Mo equivalent is as low as 4.
比較例であるＮｏ．５は、Ｍｏ当量が２２と高く、衝撃値が１．８Ｊ×１０２／ｃｍ２と小さい。
No. which is a comparative example. 5 has a high Mo equivalent of 22, and an impact value as small as 1.8 J × 10 2 / cm 2 .
比較例であるＮｏ．６は、Ｍｏ当量が６．７と低く、衝撃値が１．８Ｊ×１０２／ｃｍ２と小さい。
No. which is a comparative example. 6 has a low Mo equivalent of 6.7 and an impact value as small as 1.8 J × 10 2 / cm 2 .
さらに、比較例であるＮｏ．１５は、Ｍｏ当量が５．８と低く、衝撃値が１．７Ｊ×１０２／ｃｍ２と小さい。
Furthermore, No. which is a comparative example. No. 15 has a low Mo equivalent of 5.8 and an impact value as small as 1.7 J × 10 2 / cm 2 .
表２に示すように、本発明に係るチタン複合板２は、比較例のチタン板よりも、極めて優れた耐水素脆化特性を有する。
As shown in Table 2, the titanium composite plate 2 according to the present invention has extremely excellent hydrogen embrittlement resistance as compared with the titanium plate of the comparative example.
板厚６０ｍｍ、幅１００ｍｍ、長さ１２０ｍｍの工業用純チタン２種からなるチタンスラブの上下面に、板厚１～２５ｍｍのチタン合金Ｔｉ－１５Ｖ－３Ｃｒ－３Ｓｎ－３Ａｌ板を、３×１０-３Ｔｏｒｒ以下の真空雰囲気で電子ビーム溶接により貼り合わせた。その後、８５０℃に加熱し、板厚４．８～５．０ｍｍまで熱延した。次いで、真空雰囲気で、６００～６５０℃、４～１０時間の焼鈍を施した。さらに、ショットブラスト、酸洗を行い、スケール層を除去した。
Thickness 60 mm, width 100 mm, the upper and lower surfaces of the titanium slab made of commercially pure titanium two lengths 120 mm, the titanium alloy Ti-15V-3Cr-3Sn- 3Al sheet having a thickness of 1 ~ 25mm, 3 × 10 - Bonding was performed by electron beam welding in a vacuum atmosphere of 3 Torr or less. Thereafter, it was heated to 850 ° C. and hot rolled to a plate thickness of 4.8 to 5.0 mm. Next, annealing was performed in a vacuum atmosphere at 600 to 650 ° C. for 4 to 10 hours. Furthermore, shot blasting and pickling were performed to remove the scale layer.
その後、実施例１と同様に水素吸収環境である１体積％Ｈ２＋９９％Ａｒ雰囲気で４００～５００℃、５時間暴露した後、シャルピー衝撃試験片を採取し、衝撃値を算出して水素脆化特性を評価した。
Thereafter, as in Example 1, after exposure at 400 to 500 ° C. for 5 hours in a 1% by volume H 2 + 99% Ar atmosphere, which is a hydrogen absorption environment, a Charpy impact test piece was collected, the impact value was calculated, and hydrogen embrittlement was calculated. The crystallization properties were evaluated.
表３にまとめて結果を示す。
Table 3 summarizes the results.
本発明例であるＮｏ．１～３は、化学成分、表層占有率とも本発明の範囲であり、衝撃値は２．０×１０２Ｊ／ｃｍ２以上である。
No. which is an example of the present invention. 1 to 3 are within the scope of the present invention for both chemical components and surface layer occupancy, and the impact value is 2.0 × 10 2 J / cm 2 or more.
本発明例として、板厚６０ｍｍ、幅１００ｍｍ、長さ１２０ｍｍのチタン合金Ｔｉ－１Ｆｅ－０．３５Ｏからなるチタンスラブの上下面に、板厚５ｍｍのチタン合金Ｔｉ－１５Ｖ－３Ｃｒ－３Ｓｎ－３Ａｌ板を、３×１０-３Ｔｏｒｒ以下の真空雰囲気で電子ビーム溶接により貼り合わせた。その後、８５０℃に加熱し、板厚４．８～５．０ｍｍまで熱間圧延した。次いで、真空雰囲気で、６００～６５０℃、４～１０時間の焼鈍を施した。さらに、ショットブラスト、酸洗を行い、スケール層を除去した。
As an example of the present invention, a titanium alloy Ti-15V-3Cr-3Sn-3Al plate having a thickness of 5 mm is formed on the upper and lower surfaces of a titanium slab made of a titanium alloy Ti-1Fe-0.35O having a thickness of 60 mm, a width of 100 mm, and a length of 120 mm. Were bonded together by electron beam welding in a vacuum atmosphere of 3 × 10 −3 Torr or less. Thereafter, it was heated to 850 ° C. and hot-rolled to a thickness of 4.8 to 5.0 mm. Next, annealing was performed in a vacuum atmosphere at 600 to 650 ° C. for 4 to 10 hours. Furthermore, shot blasting and pickling were performed to remove the scale layer.
比較例として表層３，４を有さない工業用純チタンＪＩＳ４種材を用いた。板厚はどちらも４．８～５ｍｍである。
As a comparative example, an industrial pure titanium JIS 4 seed material having no surface layers 3 and 4 was used. Both plate thicknesses are 4.8-5 mm.
その後、実施例２と同様に水素環境に暴露した後、シャルピー衝撃試験片を採取し、衝撃値を算出して水素脆化特性を評価した。
Thereafter, after exposure to a hydrogen environment in the same manner as in Example 2, a Charpy impact test piece was collected, and an impact value was calculated to evaluate hydrogen embrittlement characteristics.
表層３，４を有さないＴｉ－１Ｆｅ－０．３５Ｏ合金の、水素環境に暴露しない場合の衝撃値は０．３８×１０２Ｊ／ｃｍ２であった。
The impact value of the Ti-1Fe-0.35O alloy not having the surface layers 3 and 4 when not exposed to a hydrogen environment was 0.38 × 10 2 J / cm 2 .
表４にまとめて結果を示す。
Table 4 summarizes the results.
比較例であるＮｏ．１は、表層３，４を有さない場合であり、衝撃値は０．２５×１０２Ｊ／ｃｍ２と低い。
No. which is a comparative example. 1 is a case where the surface layers 3 and 4 are not provided, and the impact value is as low as 0.25 × 10 2 J / cm 2 .
本発明例であるＮｏ．２は、化学成分および表層占有率が本発明の範囲内であり、衝撃値は０．３７×１０２Ｊ／ｃｍ２と、水素環境に暴露しない場合からほとんど低下していない。
No. which is an example of the present invention. In No. 2, the chemical composition and surface layer occupancy are within the scope of the present invention, and the impact value is 0.37 × 10 2 J / cm 2 , which is almost the same as when not exposed to a hydrogen environment.
所定の合金を含有する表層３，４を有するチタン複合材２を製造する母材となるスラブには、真空アーク溶解で製造した工業用純チタン鋳塊を、熱間鍛造した後に切削加工して作製した１２４ｍｍ厚のスラブを用いた。なお、本実施例におけるチタン鋳塊の化学成分は、Ｏ：０.０３０～０.０９０％、Ｆｅ：０.０２０～０.０６０％の範囲である。
The slab, which is the base material for producing the titanium composite material 2 having the surface layers 3 and 4 containing a predetermined alloy, is cut by hot forging an industrial pure titanium ingot produced by vacuum arc melting. The produced 124 mm-thick slab was used. The chemical composition of the titanium ingot in this example is in the range of O: 0.030 to 0.090% and Fe: 0.020 to 0.060%.
スラブ表面に板厚１ｍｍの純モリブデン板を載せ、電子ビーム加熱によってスラブ表面をモリブデン板ごと３～１５ｍｍ深さを溶融し、スラブ表層全面にＭｏが固溶した領域を深さ３～１５ｍｍ形成させた。
A pure molybdenum plate with a thickness of 1 mm is placed on the slab surface, the slab surface is melted to a depth of 3 to 15 mm together with the molybdenum plate by electron beam heating, and a region where the solid solution of Mo is dissolved to a depth of 3 to 15 mm is formed on the entire surface of the slab. It was.
当該スラブを８５０℃に加熱し、厚さ５ｍｍまで熱間圧延した後に、ショットブラストおよび硝ふっ酸を用いて、表裏面ともデスケーリング処理を行った。真空あるいは不活性ガス雰囲気中で６００～７００℃まで加熱し、２４０分間保持する熱処理を行った。
The slab was heated to 850 ° C. and hot-rolled to a thickness of 5 mm, and then descaling was performed on both the front and back surfaces using shot blasting and nitric hydrofluoric acid. Heat treatment was performed in a vacuum or an inert gas atmosphere to 600 to 700 ° C. and held for 240 minutes.
本発明に加え、表層３，４を有さないチタンスラブを用いて同様に、熱間圧延、デスケーリングおよび熱処理の工程を行い、比較例を作製した。
In addition to the present invention, a hot rolling, descaling and heat treatment steps were similarly performed using a titanium slab having no surface layers 3 and 4 to produce a comparative example.
上記で製造した各チタン板を、水素吸収環境である１体積％Ｈ２＋９９体積％Ａｒ雰囲気で５００℃、５時間暴露した。
Each titanium plate produced above was exposed at 500 ° C. for 5 hours in a 1% by volume H 2 + 99% by volume Ar atmosphere as a hydrogen absorption environment.
各チタン板から、板厚（４．８～５．０ｍｍ）×１０ｍｍ×５５ｍｍ、２ｍｍＶノッチの衝撃試験片を作製した。試験片の長手方向を圧延方向とし、ノッチの方向は板厚貫通方向とした。水素脆性は衝撃値で評価した。
From each titanium plate, an impact test piece having a thickness (4.8 to 5.0 mm) × 10 mm × 55 mm and 2 mmV notch was prepared. The longitudinal direction of the test piece was the rolling direction, and the notch direction was the plate thickness penetration direction. Hydrogen brittleness was evaluated by impact value.
まず、表層に合金元素濃化領域が無い場合、上記の水素環境に暴露後の衝撃値は、１．４×１０２Ｊ／ｃｍ２まで低下した。この結果を表５のＮｏ．１に記載する。
First, if there is no alloy element concentrated region in the surface layer, the impact value after exposure to the hydrogen environment was reduced to 1.4 × 10 2 J / cm 2 . The results are shown in Table 5. It is described in 1.
次に、表層３，４を有する本発明例のチタン複合材２の実施例を説明する。
表層３，４の合金元素濃度は、ＥＰＭＡを用いて、表面から合金濃化部の下端までの範囲を線分析した結果の平均値である。残部は、ＯやＣなどのコンタミ成分を除いて、工業用純チタンに含まれる成分である。結果を表５にまとめて示す。 Next, an example of thetitanium composite material 2 of the present invention example having the surface layers 3 and 4 will be described.
The alloy element concentrations of the surface layers 3 and 4 are average values as a result of performing a line analysis on the range from the surface to the lower end of the alloy concentrated portion using EPMA. The remainder is a component contained in industrial pure titanium except for contamination components such as O and C. The results are summarized in Table 5.
表層３，４の合金元素濃度は、ＥＰＭＡを用いて、表面から合金濃化部の下端までの範囲を線分析した結果の平均値である。残部は、ＯやＣなどのコンタミ成分を除いて、工業用純チタンに含まれる成分である。結果を表５にまとめて示す。 Next, an example of the
The alloy element concentrations of the surface layers 3 and 4 are average values as a result of performing a line analysis on the range from the surface to the lower end of the alloy concentrated portion using EPMA. The remainder is a component contained in industrial pure titanium except for contamination components such as O and C. The results are summarized in Table 5.
Ｎｏ．２～５は、表層３，４にＭｏを単独で濃化させたものである。比較例であるＮｏ．２はＭｏ当量が３３と高いため、衝撃値が１．６×１０２Ｊ／ｃｍ２と小さい。
No. In Nos. 2 to 5, Mo is concentrated on the surface layers 3 and 4 independently. No. which is a comparative example. Since 2 has a high Mo equivalent of 33, the impact value is as small as 1.6 × 10 2 J / cm 2 .
本発明例であるＮｏ．３～５は、表層３，４のＭｏ当量が８．３～１７％、板厚に対する合金層厚みの比率が８．１～１９％であり、本発明の範囲を満たし、衝撃値が２．４～２．６×１０２Ｊ／ｃｍ２と２．０Ｊ／ｃｍ２以上である。
No. which is an example of the present invention. Nos. 3 to 5 have Mo equivalents of the surface layers 3 and 4 of 8.3 to 17% and a ratio of the alloy layer thickness to the plate thickness of 8.1 to 19%, satisfying the scope of the present invention and having an impact value of 2. 4 to 2.6 × 10 2 J / cm 2 and 2.0 J / cm 2 or more.
スラブ表面に、Ｍｏ、Ｖ、Ｎｂの粉末を撒き、電子ビーム加熱によってスラブ表面を合金粉末ごと２～８ｍｍ深さを溶融し、スラブ表層全面に合金元素が固溶した領域を深さ２～８ｍｍ形成させた。
Mo, V, Nb powder is sprinkled on the slab surface, the slab surface is melted to a depth of 2 to 8 mm together with the alloy powder by electron beam heating, and a depth of 2 to 8 mm is obtained on the entire surface of the slab layer where the alloy elements are dissolved. Formed.
当該スラブを８５０℃に加熱し、厚さ５mmまで熱間圧延した後に、ショットブラストおよび硝ふっ酸を用いて、表裏面ともデスケーリング処理を行った。真空あるいは不活性ガス雰囲気中で６００～７００℃まで加熱し、２４０分間保持する熱処理を行った。
The slab was heated to 850 ° C. and hot-rolled to a thickness of 5 mm, and then descaling treatment was performed on both the front and back surfaces using shot blasting and nitric hydrofluoric acid. Heat treatment was performed in a vacuum or an inert gas atmosphere to 600 to 700 ° C. and held for 240 minutes.
上記で製造した各チタン板を、水素吸収環境である１体積％Ｈ２＋９９体積％Ａｒ雰囲気で５００℃、５時間暴露した。
Each titanium plate produced above was exposed at 500 ° C. for 5 hours in a 1% by volume H 2 + 99% by volume Ar atmosphere as a hydrogen absorption environment.
各チタン板から、板厚（４．８～５．０ｍｍ）×１０ｍｍ×５５ｍｍ、２ｍｍＶノッチの衝撃試験片を作製した。ノッチの方向は、板厚貫通方向とした。水素脆性は、シャルピー衝撃試験の衝撃値で評価した。
From each titanium plate, an impact test piece having a thickness (4.8 to 5.0 mm) × 10 mm × 55 mm and 2 mmV notch was prepared. The direction of the notch was the plate thickness penetration direction. Hydrogen embrittlement was evaluated by the impact value of the Charpy impact test.
表層３，４の合金元素濃度は、ＥＰＭＡを用いて、表面から合金濃化部までの範囲を線分析した結果の平均値である。残部は、ＯやＣなどのコンタミ成分を除いて、工業用純チタンに含まれる成分である。また、水素環境下での暴露条件は、すべて５００℃、５時間であり、表５のＮｏ．３に相当する。結果を表６にまとめて示す。
The alloy element concentration of the surface layers 3 and 4 is an average value as a result of performing a line analysis on the range from the surface to the alloy concentrated portion using EPMA. The remainder is a component contained in industrial pure titanium except for contamination components such as O and C. The exposure conditions under a hydrogen environment are all 500 ° C. and 5 hours. It corresponds to 3. The results are summarized in Table 6.
Ｎｏ．１～７は、いずれも表層占有率（合金層の厚みの全厚に対する比率）は、３～５％であり、本発明の範囲を満たしている。
No. Each of Nos. 1 to 7 has a surface layer occupation ratio (ratio of the thickness of the alloy layer to the total thickness) of 3 to 5%, which satisfies the scope of the present invention.
本発明例であるＮｏ．１は、Ｍｏ当量で１１．３のＭｏとＶを含み、衝撃値は２．０×１０２Ｊ／ｃｍ２以上である。
No. which is an example of the present invention. 1 includes Mo and V of 11.3 in Mo equivalent, and the impact value is 2.0 × 10 2 J / cm 2 or more.
本発明例であるＮｏ．２は、Ｍｏ当量で９．１のＭｏとＮｂを含み、衝撃値は２．０×１０２Ｊ／ｃｍ２以上である。
No. which is an example of the present invention. 2 includes Mo and Nb of 9.1 in terms of Mo equivalent, and the impact value is 2.0 × 10 2 J / cm 2 or more.
本発明例であるＮｏ．３は、Ｍｏ当量で１１．２のＭｏ、Ｖ、Ｎｂを含み、衝撃値は２．０×１０２Ｊ／ｃｍ２以上である。
No. which is an example of the present invention. 3 includes Mo, 11.2 Mo, V, and Nb in terms of Mo equivalent, and the impact value is 2.0 × 10 2 J / cm 2 or more.
本発明例であるＮｏ．４は、Ｍｏ当量で１０．０のＶを含み、衝撃値は２．０×１０２Ｊ／ｃｍ２以上である。
No. which is an example of the present invention. 4 includes 10.0 V in Mo equivalent and an impact value of 2.0 × 10 2 J / cm 2 or more.
本発明例であるＮｏ．５は、Ｍｏ当量で１１．７のＶとＮｂを含み、衝撃値は２．０×１０２Ｊ／ｃｍ２以上である。
No. which is an example of the present invention. 5 contains 11.7 V in terms of Mo and Nb, and the impact value is 2.0 × 10 2 J / cm 2 or more.
本発明例であるＮｏ．６は、Ｍｏ当量で１４．０のＭｏとＮｂを含み、衝撃値は２．０×１０２Ｊ／ｃｍ２以上である。
No. which is an example of the present invention. 6 contains Mo and Nb of 14.0 in terms of Mo, and the impact value is 2.0 × 10 2 J / cm 2 or more.
これに対し、比較例であるＮｏ．７は、ＭｏをＭｏ当量で４．０しか含んでおらず、衝撃値は２．０×１０２Ｊ／ｃｍ２未満であった。
On the other hand, No. which is a comparative example. 7 contained only 4.0 Mo in terms of Mo, and the impact value was less than 2.0 × 10 2 J / cm 2 .
１，２ 本発明に係るチタン複合材
３，４ 表層
５ 内層
６ 母材（スラブ）
７，８ 表層材（チタン板）
９ 溶接部 1, 2 Titanium composites 3, 4 according to the present invention Surface layer 5 Inner layer 6 Base material (slab)
7,8 Surface material (titanium plate)
9 Welded part
３，４ 表層
５ 内層
６ 母材（スラブ）
７，８ 表層材（チタン板）
９ 溶接部 1, 2
7,8 Surface material (titanium plate)
9 Welded part
Claims (7)
- 工業用純チタンまたはチタン合金からなる内層と、
前記内層の少なくとも一方の圧延面に形成された前記内層とは異なる化学組成を有する表層と、
前記内層と前記表層との間に形成され、前記内層とは異なる化学組成を有する中間層と、
を備えるチタン複合材であって、
前記表層が、その厚さが２μｍ以上であり、全厚さに占める割合が片面あたり４０％以下であり、
前記表層部の化学組成が、
Ｍｏ、ＶおよびＮｂから選択される一種以上を含有し、下記（１）式で算出されるＭｏ当量が８．０を超え２０．０未満、残部がチタンおよび不純物であり、
前記中間層の厚さが０．５μｍ以上である、
チタン複合材。
Ｍｏ当量＝Ｍｏ含有量（質量％）＋Ｖ含有量（質量％）／１．５＋Ｎｂ含有量（質量％）／３．６ （１） An inner layer made of pure titanium or titanium alloy for industrial use;
A surface layer having a chemical composition different from that of the inner layer formed on at least one rolling surface of the inner layer;
An intermediate layer formed between the inner layer and the surface layer and having a different chemical composition from the inner layer;
A titanium composite comprising:
The surface layer has a thickness of 2 μm or more, and the proportion of the total thickness is 40% or less per side,
The chemical composition of the surface layer part is
One or more selected from Mo, V and Nb, the Mo equivalent calculated by the following formula (1) is more than 8.0 and less than 20.0, the balance being titanium and impurities,
The intermediate layer has a thickness of 0.5 μm or more.
Titanium composite material.
Mo equivalent = Mo content (% by mass) + V content (% by mass) /1.5+Nb content (% by mass) /3.6 (1) - 前記内層の圧延面以外の面に、他の表層が形成されており、
前記他の表層が、前記表層と同一の化学組成を備える、
請求項１に記載のチタン複合材。 Other surfaces are formed on the surface other than the rolling surface of the inner layer,
The other surface layer has the same chemical composition as the surface layer,
The titanium composite according to claim 1. - 工業用純チタンまたはチタン合金からなる母材と、
前記母材の少なくとも一方の圧延面に接合された表層材と、
前記母材と前記表層材の周囲を接合する溶接部とを備える熱間圧延用チタン材であって、
前記表層材が、前記母材とは異なる化学組成を有し、かつ、
Ｍｏ、ＶおよびＮｂから選択される一種以上を含有し、下記（１）式で算出されるＭｏ当量が８．０を超え２０．０未満、残部がチタンおよび不純物であり、
前記溶接部が、前記母材と前記表層材の界面を外気から遮断する、
熱間圧延用チタン材。
Ｍｏ当量＝Ｍｏ含有量（質量％）＋Ｖ含有量（質量％）／１．５＋Ｎｂ含有量（質量％）／３．６ （１） A base material made of pure titanium or titanium alloy for industrial use;
A surface layer material joined to at least one rolling surface of the base material;
A titanium material for hot rolling comprising a welded portion that joins the periphery of the base material and the surface layer material,
The surface layer material has a different chemical composition from the base material, and
One or more selected from Mo, V and Nb, the Mo equivalent calculated by the following formula (1) is more than 8.0 and less than 20.0, the balance being titanium and impurities,
The welded portion shields the interface between the base material and the surface material from outside air;
Titanium material for hot rolling.
Mo equivalent = Mo content (% by mass) + V content (% by mass) /1.5+Nb content (% by mass) /3.6 (1) - 前記母材の圧延面以外の面に、他の表層材が接合されており、
前記他の表層材が、前記表層材と同一の化学組成を備える、
請求項３に記載の熱間圧延用チタン材。 Other surface layer materials are joined to a surface other than the rolling surface of the base material,
The other surface layer material has the same chemical composition as the surface layer material,
The titanium material for hot rolling according to claim 3. - 前記母材が、直接鋳造スラブからなる、
請求項３または４に記載の熱間圧延用チタン材。 The base material consists of a direct cast slab,
The titanium material for hot rolling according to claim 3 or 4. - 前記直接鋳造スラブが、表面の少なくとも一部に溶融再凝固層を形成したものである、
請求項５に記載の熱間圧延用チタン材。 The direct cast slab is obtained by forming a melt resolidified layer on at least a part of the surface.
The titanium material for hot rolling according to claim 5. - 前記溶融再凝固層の化学組成が、前記直接鋳造スラブの板厚中心部の化学組成とは異なる、
請求項６に記載の熱間圧延用チタン材。
The chemical composition of the melt-resolidified layer is different from the chemical composition of the center thickness of the direct cast slab,
The titanium material for hot rolling according to claim 6.
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| CN115739993A (en) * | 2022-11-18 | 2023-03-07 | 浙江申吉钛业股份有限公司 | Preparation method of wide titanium alloy plate |
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| WO2014163089A1 (en) * | 2013-04-01 | 2014-10-09 | 新日鐵住金株式会社 | Titanium slab for hot rolling and method for manufacturing same |
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| JP4486530B2 (en) * | 2004-03-19 | 2010-06-23 | 新日本製鐵株式会社 | Heat-resistant titanium alloy plate excellent in cold workability and method for producing the same |
| JP5130850B2 (en) * | 2006-10-26 | 2013-01-30 | 新日鐵住金株式会社 | β-type titanium alloy |
| JP2016128171A (en) * | 2013-04-01 | 2016-07-14 | 新日鐵住金株式会社 | Titanium hot rolling slab being hard to cause surface flaw and its manufacturing method |
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| JPS50146557A (en) * | 1974-05-16 | 1975-11-25 | ||
| JP2001038413A (en) * | 1999-07-27 | 2001-02-13 | Nkk Corp | Pack rolling method |
| WO2014163089A1 (en) * | 2013-04-01 | 2014-10-09 | 新日鐵住金株式会社 | Titanium slab for hot rolling and method for manufacturing same |
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| JP2019181563A (en) * | 2018-04-04 | 2019-10-24 | ザ・ボーイング・カンパニーＴｈｅＢｏｅｉｎｇ Ｃｏｍｐａｎｙ | Welded titanium structure utilizing dissimilar titanium alloy filler metal for enhanced fatigue life |
| JP7299038B2 (en) | 2018-04-04 | 2023-06-27 | ザ・ボーイング・カンパニー | Welded Titanium Structures Utilizing Dissimilar Titanium Alloy Fillers for Improved Fatigue Life |
| CN115739993A (en) * | 2022-11-18 | 2023-03-07 | 浙江申吉钛业股份有限公司 | Preparation method of wide titanium alloy plate |
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