CN111055042A - High heat input welded joint with excellent fatigue performance - Google Patents
High heat input welded joint with excellent fatigue performance Download PDFInfo
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- CN111055042A CN111055042A CN201911207964.2A CN201911207964A CN111055042A CN 111055042 A CN111055042 A CN 111055042A CN 201911207964 A CN201911207964 A CN 201911207964A CN 111055042 A CN111055042 A CN 111055042A
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- 238000003466 welding Methods 0.000 claims abstract description 80
- 229910052751 metal Inorganic materials 0.000 claims abstract description 74
- 239000002184 metal Substances 0.000 claims abstract description 74
- 239000000126 substance Substances 0.000 claims abstract description 21
- 238000000034 method Methods 0.000 claims abstract description 15
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 229910000859 α-Fe Inorganic materials 0.000 claims description 20
- 239000000203 mixture Substances 0.000 claims description 14
- 229910052759 nickel Inorganic materials 0.000 claims description 12
- 229910052804 chromium Inorganic materials 0.000 claims description 11
- 229910052758 niobium Inorganic materials 0.000 claims description 10
- 229910052720 vanadium Inorganic materials 0.000 claims description 10
- 229910052750 molybdenum Inorganic materials 0.000 claims description 9
- 229910052782 aluminium Inorganic materials 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 8
- 229910052684 Cerium Inorganic materials 0.000 claims description 7
- 229910052796 boron Inorganic materials 0.000 claims description 7
- 229910052749 magnesium Inorganic materials 0.000 claims description 7
- 229910052726 zirconium Inorganic materials 0.000 claims description 7
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 20
- 230000007704 transition Effects 0.000 description 9
- 239000013078 crystal Substances 0.000 description 7
- 230000006911 nucleation Effects 0.000 description 7
- 238000010899 nucleation Methods 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000009661 fatigue test Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000005275 alloying Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
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- 238000009440 infrastructure construction Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000002667 nucleating agent Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
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Classifications
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- 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
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
- B23K35/3026—Mn as the principal constituent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Arc Welding In General (AREA)
- Butt Welding And Welding Of Specific Article (AREA)
Abstract
The invention discloses a high heat input welding joint with excellent fatigue performance, wherein the welding seam metal comprises the following chemical components in percentage by weight: 0.005-0.050% of C, 0.01-0.30% of Si, 2.5-4.5% of Mn, 0.05-0.50% of Mo0.1-1.5% of Ni, 0.005-0.050% of Ti, 0.0005-0.0050% of B, less than or equal to 0.015% of P, less than or equal to 0.010% of S, less than or equal to 0.02% of Al, and the following contents are satisfied: 90 < M < 160, wherein M is 425.3[ C [)]+29.5[Mn]+18.7[Ni]+8.2[Mo]；[Ti]/[Al]≥4，[]The weight percentages (%) of the elements are shown, and the balance is Fe and inevitable impurities; the number N (number/mm) of inclusions with an equivalent circle diameter of more than 0.2 [ mu ] m in the weld metal3) Satisfies the following conditions: 3.0X 107≤N≤1.5×108. The welding joint can be welded by a large heat input welding method of more than 200KJ/cm, has good fatigue resistance, and can be used for welding large components bearing alternating loads.
Description
Technical Field
The invention belongs to the technical field of welding, and particularly relates to a high-heat-input welding joint with excellent fatigue performance.
Background
At the present high-speed development stage of infrastructure construction in China, the manufacture of engineering structures such as high-rise buildings, large-span bridges, large ships, ocean platforms and the like gradually develops towards large-scale. In order to improve the engineering efficiency, various large heat input welding methods are widely applied to different fields, such as electroslag welding which is suitable for welding box columns and box beam partition plates of high-rise buildings, electro-gas welding which is suitable for welding large closure joints of large ship block sections, multi-wire submerged arc welding which is suitable for splicing welding of long straight welding seams and the like. The large engineering structure inevitably suffers from severe working conditions such as bearing load change, wind, wave and the like in the service process, and is required to have higher fatigue performance for improving the safety coefficient, but the welding seam and the heat affected zone of the current large heat input welding have thick structures, so that the welding joint becomes the weakest part of the fatigue performance in the whole structure.
In the related art disclosed so far, patent CN100430174A discloses a welded joint of a large input heat type welding and a welding method thereof, which mainly adds a large amount of boron into a welding wire, and the boron diffuses to a heat affected zone during welding to improve the low temperature toughness of the zone, but does not mention the fatigue property of the welded joint, and the carbon content of the weld metal is higher, which significantly increases the crack sensitivity of the welded joint.
Patents CN109128573A and CN109128585A disclose a gas shielded flux-cored wire for large heat input electro-gas welding, in which the aluminum content in the weld metal is too high, and the formed aluminum oxide brittle inclusions with large size are liable to become the origin of fatigue cracks, thereby reducing the fatigue performance of the welded joint.
Patent CN103350290A discloses a solid welding wire for electroslag welding of low temperature steel plate, which focuses on improving the low temperature toughness of the weld metal, so the nickel content in the welding wire is high, but does not mention the fatigue performance of the welded joint, and the weld metal has high carbon and nickel content, which has the problems of high content of alloy elements and poor crack resistance.
Patent CN103917327A discloses a welded joint capable of greatly improving fatigue strength of fillet welded part between gusset plate and high-strength plate, wherein the fatigue property of the welded joint can be improved by using low phase change point welding material to make martensite phase change starting point of welding metal below 350 ℃, and residual compressive stress generated on the surface of welding seam by low temperature phase change, but the low phase change point welding material has the problems of high content of alloy elements, and inferior mechanical property and crack resistance to common welding material, so that it has not reached the degree of real practical use.
The patent CN102632348A discloses a solid welding wire for improving the fatigue property of a high-strength steel welding joint of engineering machinery, but the welding wire is only used for argon arc welding or gas shielded welding with small heat input, and the thickness of a welding steel plate is not more than 20 mm. In addition, the welding wire has high content of noble alloy elements Ni and Cr, so that the welding cost is high.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a high-heat-input welding joint with excellent fatigue performance, and through reasonable component design on welding seam metal, on one hand, the grain size of the welding seam metal is refined, the proportion of grain boundary ferrite in the welding joint is reduced, and on the other hand, the state of residual stress in the welding seam is changed, so that the requirement of a large engineering structure on the fatigue performance in service under severe working conditions is met.
In order to achieve the purpose, the invention provides the following technical scheme:
the embodiment of the application discloses a high heat input welding joint with excellent fatigue performance, which is formed by welding by adopting a high heat input welding method of more than 200KJ/cm, and the welding joint meets the following requirements: 1) the welding seam metal comprises the following chemical components in percentage by weight:
c: 0.005-0.050%, Si: 0.01-0.30%, Mn: 2.5-4.5%, Mo: 0.05 to 0.50%, Ni: 0.1-1.5%, Ti: 0.005-0.050%, B: 0.0005-0.0050%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Al is less than or equal to 0.02%, and the balance of Fe and inevitable impurities;
2) the chemical composition of the weld metal satisfies the following conditions: m is more than or equal to 90 and less than or equal to 160, wherein: m ═ 425.3[ C ] +29.5[ Mn ] +18.7[ Ni ] +8.2[ Mo ], [ ] indicates the weight percentage (%) of each element;
3) the chemical composition of the weld metal satisfies the following conditions: [ Ti ]/[ Al ]. gtoreq.4, wherein: [] Represents the weight percentage (%) of each element;
4) the number N (pieces/mm 3) of inclusions with the equivalent circle diameter of more than 0.2 mu m in the weld metal satisfies the following conditions: 3.0X 107≤N≤1.5×108。
Preferably, the chemical composition of the weld metal contains one or two of Cr and Cu, and the content of Cr and Cu is 0.01-0.30% by weight.
Preferably, the chemical composition of the weld metal contains one or two of Nb and V, and the Nb and V are contained in the range of 0.002-0.050% by weight.
Preferably, the chemical composition of the weld metal contains any one or more of Zr, Mg and Ce, and the content of Zr, Mg and Ce in percentage by weight is 0.0005-0.0300%.
Preferably, the area percentage of grain boundary ferrite in the weld joint and the heat affected zone of the welded joint is less than 15%.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) according to the invention, on one hand, through the optimized design of Al, Ti and B elements, the grain size of weld metal is refined, and the proportion of grain boundary ferrite in a welding joint is reduced, on the other hand, through the reasonable proportion of Mn, Ni and Mo elements, the state of residual stress in the weld joint is changed, the fatigue life of the large heat input welding joint in service under severe working conditions is prolonged, and the safety of a large engineering structure is improved.
(2) The welding seam metal has less contents of noble alloy elements such as Ni, Mo and Cr, and the like, and can effectively reduce the welding cost.
Detailed Description
Technical solutions in the embodiments of the present invention will be described in detail below, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
A large heat input welded joint excellent in fatigue properties, which satisfies: 1) the welding seam metal comprises the following chemical components in percentage by weight:
c: 0.005-0.050%, Si: 0.01-0.30%, Mn: 2.5-4.5%, Mo: 0.05 to 0.50%, Ni: 0.1-1.5%, Ti: 0.005-0.050%, B: 0.0005-0.0050%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Al is less than or equal to 0.02%, and the balance of Fe and inevitable impurities;
2) the chemical composition of the weld metal satisfies the following conditions: m is more than or equal to 90 and less than or equal to 160, wherein: m ═ 425.3[ C ] +29.5[ Mn ] +18.7[ Ni ] +8.2[ Mo ], [ ] indicates the weight percentage (%) of each element;
3) the chemical composition of the weld metal satisfies the following conditions: [ Ti ]/[ Al ]. gtoreq.4, wherein: [] Represents the weight percentage (%) of each element;
4) the number N (pieces/mm 3) of inclusions with the equivalent circle diameter of more than 0.2 mu m in the weld metal satisfies the following conditions: 3.0X 107≤N≤1.5×108。
Preferably, the chemical composition of the weld metal contains one or two of Cr and Cu, and the content of Cr and Cu is 0.01-0.30% by weight.
Preferably, the chemical composition of the weld metal contains one or two of Nb and V, and the Nb and V are contained in the range of 0.002-0.050% by weight.
Preferably, the chemical composition of the weld metal contains any one or more of Zr, Mg and Ce, and the content of Zr, Mg and Ce in percentage by weight is 0.0005-0.0300%.
Preferably, the area percentage of grain boundary ferrite in the weld joint and the heat affected zone of the welded joint is less than 15%.
Further, it has been found through intensive studies on welded joints for electrogas welding, multi-wire submerged arc welding and electroslag welding of 200KJ/cm or more that: because the stay time of the weld metal in the high-temperature area is longer during the large heat input welding and the cooling time t after welding8/5The time for cooling the weld metal from 800 ℃ to 500 ℃ is longer, which results in that the weld metal has large columnar grain size, and the proportion and size of the reticular grain boundary ferrite precipitated at the prior austenite grain boundary in the weld and the heat affected zone are larger, so that fatigue cracks are easy to be initiated and propagated at the grain boundary ferrite. Researches show that the inclusions can be used as a heterogeneous nucleating agent to promote the nucleation of the crystal interior on one hand and can inhibit the growth of austenite crystal grains on the other hand, so that the appropriate size and number of the inclusions can adjust the tissue type of a welded joint and reduce the area percentage of grain boundary ferrite. Based on this, the invention specifies [ Ti ] in the weld metal]/[Al]The number N (pieces/mm 3) of inclusions which are not less than 4(2) and have an equivalent circle diameter of more than 0.2 [ mu ] m satisfies: 3.0X 107≤N≤1.5×108(3). According to the specification, the welded joint of the invention simultaneously inhibits the initiation and the propagation of fatigue cracks at aluminum inclusions or grain boundary ferrite, and the fine structure is beneficial to improving the strength and the toughness of the welded joint.
The present inventors have made extensive studies to solve the above problems and found that the state and distribution of the residual stress of a welded joint have a great influence on fatigue properties: the contents and proportional relationships of the alloying elements C, Mn, Ni and Mo have a correlation with the state of the residual stress of the welded joint, and a function M consisting of the weight percentages of the elements is established through experiments. Wherein M is 425.3[ C ] +29.5[ Mn ] +18.7[ Ni ] +8.2[ Mo ], where [ ] represents the weight percentage (%) of each element. Furthermore, the inspection of the weld metal with different M values shows that when the M value meets 90-160 (1), on one hand, the residual stress in the weld metal is converted from tensile stress to compressive stress, so that the fatigue strength of a welded joint is improved, and on the other hand, the content of Ni and Mo noble elements is controlled within a reasonable range, so that the production cost is reduced, and the crack resistance and the low-temperature toughness of the weld metal are improved. When the value of M is lower than 90, the phase transition temperature of the weld metal is not obviously reduced, the improvement effect on the stress state is limited, and when the value of M is higher than 160 ℃, the weldability is deteriorated.
The welded joint of the present invention satisfies the above formulas (1) and (2) in terms of the chemical composition of the weld metal, and satisfies the formula (3) in terms of the inclusion of the weld metal, so as to obtain a welded joint with high heat input excellent in fatigue properties, but if the contents of the respective elements are not within the appropriate ranges, the above object cannot be achieved. Therefore, the welded joint of the present invention is required to have the contents of the respective elements within the appropriate ranges described below, in addition to satisfying the above formulas (1), (2) and (3).
The contents of the respective elements will be described below.
C: is one of important elements in weld metal, has obvious effect on improving the strength, can reduce the phase transition temperature of the weld metal and improve the stress state of a welding joint. If the content of C is too low, the phase transition temperature of the weld metal is not obviously reduced, and if the content of C is too high, the weldability is deteriorated, and the cold cracking tendency is increased. Therefore, the C content is preferably controlled to be in the range of 0.005 to 0.050%.
Si: is the main deoxidizing element in the welding process. If the content of Si is too low, deoxidation is insufficient, so that the oxygen content in the welding seam is too high, the impact toughness is deteriorated, and if the content is too high, the generation of widmannstatten structures and side plate bar ferrites is remarkably promoted, and the fatigue performance is deteriorated. Therefore, the Si content is preferably controlled to be in the range of 0.01 to 0.30%.
Mn: is an important strengthening element in weld metal, and can reduce the phase transition temperature of the weld metal and improve the stress state of a welding joint. If the content of Mn is too low, the phase transition temperature of the weld metal is not obviously reduced, and if the content of Mn is too high, the strength of the weld metal is excessively increased. Therefore, the Mn content is preferably controlled to be in the range of 2.5 to 4.5%.
Mo: is an important strengthening element in weld metal, and can reduce the phase transition temperature of the weld metal and improve the stress state of a welding joint. If the content of Mo is too low, the phase transition temperature of the weld metal is not obviously reduced, and if the content of Mo is too high, the hardenability and the cold cracking tendency are increased. Therefore, the Mo content is preferably controlled to be 0.05 to 0.50%.
Ni: is an important element for improving the toughness of the weld metal, and can reduce the phase transition temperature of the weld metal and improve the stress state of a welding joint. If the Ni content is too low, the phase transition temperature of the weld metal is not obviously reduced, and if the Ni content is too high, the heat crack resistance of the weld metal is reduced and the welding cost is increased. Therefore, the Ni content is preferably controlled to be in the range of 0.1 to 1.5%.
Ti: is an important microalloy element in weld metal, and Ti oxide can promote the nucleation of acicular ferrite in crystal, refine the effective crystal grain size of the weld and synchronously improve the toughness and fatigue property of the weld. If the Ti content is too low, the amount of inclusions in the weld metal is limited, which is not beneficial to the nucleation of ferrite in the crystal, and if the Ti content is too high, the amount of inclusions in the weld metal is too large, which deteriorates the toughness. Therefore, the Ti content is preferably controlled to 0.005 to 0.050%.
B: is an important microalloy element in weld metal, and B is segregated in austenite grain boundaries to inhibit the nucleation of grain boundary ferrite and improve the fatigue performance. If the content of B is too low, the effect of suppressing grain boundary ferrite nucleation is not significant, and if the content is too high, coarse bainite is likely to be formed, thereby deteriorating toughness. Therefore, the content of B is preferably controlled to 0.0005 to 0.0050%.
P, S: is an impurity element in weld metal and is unfavorable for the low-temperature toughness of the weld. Therefore, the P content is preferably controlled to be less than or equal to 0.015%, and the S content is preferably controlled to be less than or equal to 0.010%.
Al: is an important deoxidizing element in weld metal, the weld deoxidation is insufficient when the Al content is too low, the quantity of aluminum inclusions in steel is increased when the content is too high, and the fatigue property of a wire rod is deteriorated. Therefore, the Al content is preferably controlled to be less than or equal to 0.02%.
Cr, Cu: is the main strengthening element in the weld metal and can be added according to the requirement. If the contents of Cr and Cu are too low, the weld metal strength is insufficient, and if the contents are too high, the weldability deteriorates. Therefore, the content of Cr and Cu is preferably controlled to be in the range of 0.01 to 0.30%.
Nb, V: is an important micro-alloy element in weld metal, can refine weld structures and improve fatigue performance, and can be added according to requirements. If the Nb and V contents are too low, the effect of refining the structure is limited, and if the Nb and V contents are too high, the toughness of the weld joint is deteriorated. Therefore, the Nb and V contents are preferably controlled to be in the range of 0.002 to 0.050%.
Zr, Mg and Ce: is an important microalloy element in weld metal, and the oxide of the microalloy element can promote the nucleation of acicular ferrite in the crystal, refine the effective grain size of the weld, synchronously improve the toughness and the fatigue property of the weld and can be added according to requirements. If the Zr content, the Mg content and the Ce content are too low, the quantity of inclusions in weld metal is limited, which is not beneficial to the nucleation of ferrite in crystal, and if the Zr content, the Mg content and the Ce content are too high, the quantity of inclusions in weld metal is too much, which deteriorates the toughness. Therefore, the Zr content, the Mg content and the Ce content are preferably controlled to be in the range of 0.0005 to 0.0300%.
Example (b): the welding method with heat input of more than 200KJ/cm, such as electro-gas welding, electroslag welding, multi-wire submerged arc welding and the like, is adopted to obtain a large heat input welding joint, and the chemical components of the welding seam metal are shown in table 1.
For the above welded joint, the M value calculated from the chemical composition of the weld metal, [ Ti ]/[ Al ], the number N of inclusions having an equivalent circle diameter of more than 0.2 μ M, the area percentage of grain boundary ferrite, the mechanical properties of the welded joint, and the fatigue life are shown in Table 2.
Wherein the number N of inclusions having an equivalent circle diameter of more than 0.2 μm is measured by the following method: selecting 60 fields at random under 1500 magnification by using a scanning electron microscopeThe total area is 2.38X 105 μm2The number of inclusions is not less than 1620; analyzing the sizes of the inclusions in the visual field one by one through Smart SEM software; the number of inclusions N is determined by the formula N ═ Ns x (1/d)0)×(1+σ/d0) Converted from the areal density Ns, wherein d0And the average diameter of the inclusions, sigma is the standard deviation, and Ns is the number of inclusions in a unit area counted by Smart SEM software.
The area percentage of grain boundary ferrite is determined as follows: and (3) adopting a metallographic microscope, randomly selecting 5 fields to shoot weld metal or weld coarse grain region tissues under the magnification of 200, and adopting image processing software to determine the area percentage of grain boundary ferrite.
The fatigue life was measured as follows: three-point bending fatigue test is carried out by adopting a high-frequency fatigue testing machine, and the maximum stress is 0.5 sigmab(σbTensile strength of welded joint), stress ratio was 0.1, and the number of cycles at which fatigue fracture occurred in the material, i.e., fatigue life, was tested.
Examples 1 to 8, which employ the weld metal of the present invention and satisfy the conditions of the present invention, show that the fatigue properties and low-temperature toughness are excellent.
The contents of some elements or the conditions in comparative examples 1 to 4 were out of the range of the present invention, and it was found that the fatigue properties, low temperature toughness, and the like were deteriorated.
TABLE 1
TABLE 2
The above-mentioned examples only express the specific embodiments of the present invention, but should not be construed as limiting the scope of the present invention. Any modifications of the present invention which would occur to those skilled in the art and which are within the spirit of the invention are considered to be within the scope of the present invention.
The invention has at least the following beneficial effects:
(1) according to the invention, on one hand, through the optimized design of Al, Ti and B elements, the grain size of weld metal is refined, and the proportion of grain boundary ferrite in a welding joint is reduced, on the other hand, through the reasonable proportion of Mn, Ni and Mo elements, the state of residual stress in the weld joint is changed, the fatigue life of the large heat input welding joint in service under severe working conditions is prolonged, and the safety of a large engineering structure is improved.
(2) The welding seam metal has less contents of noble alloy elements such as Ni, Mo and Cr, and the like, and can effectively reduce the welding cost.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The foregoing is directed to embodiments of the present invention, and it is understood that various modifications and improvements can be made by those skilled in the art without departing from the spirit of the invention.
Claims (5)
1. A high heat input welding joint with excellent fatigue performance is welded by a high heat input welding method of more than 200KJ/cm, and is characterized in that: the welded joint satisfies: 1) the welding seam metal comprises the following chemical components in percentage by weight:
c: 0.005-0.050%, Si: 0.01-0.30%, Mn: 2.5-4.5%, Mo: 0.05 to 0.50%, Ni: 0.1-1.5%, Ti: 0.005-0.050%, B: 0.0005-0.0050%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Al is less than or equal to 0.02%, and the balance of Fe and inevitable impurities;
2) the chemical composition of the weld metal satisfies the following conditions: m is more than or equal to 90 and less than or equal to 160, wherein: m ═ 425.3[ C ] +29.5[ Mn ] +18.7[ Ni ] +8.2[ Mo ], [ ] indicates the weight percentage (%) of each element;
3) the chemical composition of the weld metal satisfies the following conditions: [ Ti ]/[ Al ]. gtoreq.4, wherein: [] Represents the weight percentage (%) of each element;
4) the number N (pieces/mm 3) of inclusions with the equivalent circle diameter of more than 0.2 mu m in the weld metal satisfies the following conditions: 3.0X 107≤N≤1.5×108。
2. A high heat input welded joint excellent in fatigue property according to claim 1, characterized in that: the welding seam metal comprises any one or two of Cr and Cu, wherein the Cr and the Cu are contained in an amount of 0.01-0.30% by weight.
3. A high heat input welded joint excellent in fatigue property according to claim 1, characterized in that: the chemical components of the weld metal comprise one or two of Nb and V, wherein the Nb and V are contained in an amount of 0.002-0.050% by weight.
4. A high heat input welded joint excellent in fatigue property according to claim 1, characterized in that: the chemical components of the weld metal comprise any one or more of Zr, Mg and Ce, and the content of Zr, Mg and Ce in percentage by weight is 0.0005-0.0300%.
5. A high heat input welded joint excellent in fatigue property according to claim 1, characterized in that: the area percentage of grain boundary ferrite in a weld joint and a heat affected zone of the welded joint is less than 15%.
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| CN109128573A (en) * | 2017-06-27 | 2019-01-04 | 宝山钢铁股份有限公司 | A kind of high heat-input electro-gas (enclosed) welding gas shielded flux cored wire based on grain refinement mechanism |
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| US5296677A (en) * | 1991-02-26 | 1994-03-22 | Kobe Steel, Ltd. | Filler metal for welding sintered materials |
| CN1347781A (en) * | 2000-10-06 | 2002-05-08 | 川崎制铁株式会社 | Submerged-arc welding point, producing method of the same welding point, and used solder wire and flux |
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