WO2022265010A1 - 溶接構造体 - Google Patents
溶接構造体 Download PDFInfo
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- WO2022265010A1 WO2022265010A1 PCT/JP2022/023798 JP2022023798W WO2022265010A1 WO 2022265010 A1 WO2022265010 A1 WO 2022265010A1 JP 2022023798 W JP2022023798 W JP 2022023798W WO 2022265010 A1 WO2022265010 A1 WO 2022265010A1
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- joined
- joint
- welded
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- welding
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- 238000003466 welding Methods 0.000 claims abstract description 53
- 239000002184 metal Substances 0.000 claims abstract description 41
- 229910052751 metal Inorganic materials 0.000 claims abstract description 41
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 9
- 238000005304 joining Methods 0.000 claims description 41
- 239000012535 impurity Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 229910052698 phosphorus Inorganic materials 0.000 claims description 3
- 229910052717 sulfur Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 19
- 239000000203 mixture Substances 0.000 abstract description 10
- 230000006378 damage Effects 0.000 abstract description 4
- 229910000831 Steel Inorganic materials 0.000 description 41
- 239000010959 steel Substances 0.000 description 41
- 238000000034 method Methods 0.000 description 15
- 230000000694 effects Effects 0.000 description 9
- 239000012071 phase Substances 0.000 description 9
- 238000005336 cracking Methods 0.000 description 7
- 238000010276 construction Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000000644 propagated effect Effects 0.000 description 5
- 125000006850 spacer group Chemical group 0.000 description 5
- 239000000969 carrier Substances 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000035515 penetration Effects 0.000 description 3
- 230000001902 propagating effect Effects 0.000 description 3
- 239000012779 reinforcing material Substances 0.000 description 3
- 238000007711 solidification Methods 0.000 description 3
- 230000008023 solidification Effects 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000010953 base metal Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000009430 construction management Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
Images
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
- B23K9/00—Arc welding or cutting
- B23K9/02—Seam welding; Backing means; Inserts
- B23K9/025—Seam welding; Backing means; Inserts for rectilinear seams
- B23K9/0256—Seam welding; Backing means; Inserts for rectilinear seams for welding ribs on plates
-
- 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
-
- 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
- B23K35/3053—Fe as the principal constituent
- B23K35/308—Fe as the principal constituent with Cr as next major constituent
- B23K35/3086—Fe as the principal constituent with Cr as next major constituent containing Ni or Mn
-
- 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
- B23K9/00—Arc 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
- B23K9/00—Arc welding or cutting
- B23K9/02—Seam welding; Backing means; Inserts
Definitions
- the present invention relates to welded steel structures (welded structures) that are welded using thick steel plates, such as large container ships and bulk carriers.
- the present invention relates to a welded structure having excellent brittle crack arrestability, which can stop the propagation of brittle cracks generated from the base material of thick steel plates or welded joints before large-scale destruction of the structure.
- container ships and bulk carriers have a structure with a large opening at the top of the ship in order to improve loading capacity and cargo handling efficiency. Therefore, in container ships and bulk carriers, it is necessary to increase the strength or increase the thickness of the hull panels.
- TEU wenty Feet Equivalent Unit
- the steel plates that form the hull shell are often butt welded by high heat input welding, such as electrogas arc welding, from the viewpoint of shortening the construction period.
- high heat input welding is likely to lead to a significant decrease in toughness in the weld heat-affected zone, and has been one of the causes of brittle cracking from the welded joint.
- Non-Patent Document 1 reports the results of an experimental study on the brittle crack propagation behavior of welds in shipbuilding steel plates with a thickness of less than 50 mm.
- Non-Patent Document 1 the propagation path and propagation behavior of brittle cracks forcibly generated in welds are experimentally investigated. This document states that if the fracture toughness of the weld zone is secured to some extent, brittle cracks often diverge from the weld zone to the base metal side due to the influence of weld residual stress. Several cases of brittle cracks propagating along the This suggests that the possibility of brittle fracture propagating straight along the weld cannot be ruled out.
- Non-Patent Document 1 there are many achievements that ships built by applying welding equivalent to the welding used in Non-Patent Document 1 to steel plates with a thickness of less than 50 mm are in service without any problems. Based on the recognition that good steel plate base materials (e.g. shipbuilding class E steel) have sufficient ability to arrest brittle cracks, the brittle crack propagation arresting properties of welded parts of shipbuilding steel materials are It wasn't specifically requested.
- good steel plate base materials e.g. shipbuilding class E steel
- Non-Patent Document 2 points out that a thick steel plate having a special brittle crack arresting property is required in order to arrest the propagation of brittle cracks that have occurred.
- Patent Document 1 discloses that, in a welded structure, which is preferably a hull plate having a thickness of 50 mm or more, an aggregate is arranged so as to intersect the butt weld portion, and fillet welding is performed. Welded structures are described that are joined by In the technique described in Patent Document 1, a steel plate having a predetermined microstructure is used as a reinforcing material and fillet-welded, so that even if a brittle crack occurs in the butt welded joint, the aggregate, which is the reinforcing material, is used. It is described that brittle fracture can be stopped at and fatal damage such as destruction of the welded structure can be prevented.
- Patent Document 2 describes a welded structure provided with a fillet-welded joint formed by fillet-welding a joining member to a member to be joined.
- a fillet-welded joint formed by fillet-welding a joining member to a member to be joined.
- an unwelded portion remains on the butting surface of the member to be joined in the cross section of the fillet welded joint with the member to be joined, and the width of the unwelded portion is determined by the brittleness of the member to be joined. It is adjusted to satisfy the crack arrestability Kca and a special relational expression.
- Patent Documents 3, 4, and 5 disclose a welded structure formed by abutting an end surface of a joining member against a surface of a member to be joined and joining the member to be joined and the member to be joined by fillet welding. Are listed.
- a non-welded portion is provided on the surface where the end face of the member to be joined and the surface of the member to be joined meet, and at least one of the weld leg length and weld width is 16 mm or less.
- the joint member has brittle crack arrestability
- a steel plate with excellent toughness or by making the welded structure of the butt weld joint with high toughness, brittle cracks generated from the welded part of the joined member are suppressed at the fillet weld or at the mother of the joined member. It is stated that the propagation can be blocked at the material or at the weld of the joining member and/or the member to be joined.
- Patent Document 6 discloses a fillet welded joint in which the end surface of a member to be joined is butted against the surface of a member to be joined having a plate thickness of 50 mm or more, and the member to be joined and the member to be joined are joined.
- a welded structure comprising: In the welded structure described in Patent Document 6, the weld leg length and welding width of the fillet welded joint exceed 16 mm, and the end surface of the member to be joined and the surface of the member to be joined in the fillet welded joint are butted against each other.
- the cross section of the fillet welded joint has an unwelded portion of 95% or more of the plate thickness tw of the member to be joined, and the smaller value L of the weld leg length and the weld width and the plate thickness tf of the member to be joined.
- Patent Document 7 describes a welded structure having a doubler member at the butted portion of the web and flange.
- the web is butt fillet welded to the doubler member, an unwelded portion remains on the butt surface, and the tabular member is overlap fillet welded to the flange, and the overlap is welded. Unwelded portions remain on the mating surfaces.
- the technique described in Patent Document 7 states that if an austenitic steel plate is used for the doubler member, propagation of long brittle cracks can be prevented by the doubler member.
- Patent Document 6 requires strict construction management during welding in order to limit the welding leg length and welding width, and there are problems such as a decrease in productivity of welding construction and an increase in construction costs. .
- Patent Document 7 has a problem that the construction cost increases due to doubler member processing and welding, and a problem that the material cost rises when using an expensive austenitic steel plate for the doubler member.
- the present invention solves the problems of the prior art as described above, and solves the problem of brittle cracks occurring in members to be joined (flanges) with a plate thickness of 50 mm or more without requiring strict construction control during welding.
- An object of the present invention is to provide a welded structure excellent in brittle crack arrestability, capable of stopping propagation to (web) before reaching large-scale fracture.
- the welded structure targeted by the present invention is a welded structure having a T joint formed by butting the end face of the joining member against the surface of the member to be joined and joining them by fillet welding or partial penetration welding. is.
- the present inventors diligently studied various factors affecting the brittle crack arrest toughness of T-joints.
- the structure of the weld metal of the T-joint is mainly composed of the austenite phase, the weld metal can be made to have high toughness. It was conceived that even when partial penetration welding is used for joining, a T-joint having excellent brittle crack arrestability can be obtained. And, as a result, propagation of brittle cracks generated in the joined member (flange) to the joined member (web) without special consideration of the brittle crack propagation arresting performance of the thick steel plate used for the joined member (web). can be prevented by the weld metal of the T-joint.
- a welded structure comprising a T joint in which the end face of a joining member is butted against the surface of a member to be joined having a plate thickness of 50 mm or more, and the member to be joined and the member to be joined are joined, ,
- the welding leg length or welding width of the T-joint is 16 mm or more, and furthermore, on the surface where the end surface of the joining member and the surface of the member to be joined in the T-joint are butted, the cross-section of the joining member is There is an unwelded part of 30% or more of the plate thickness
- a welded structure, wherein the weld metal of the T-joint has a structure containing 80% or more of an austenite phase in terms of area %.
- the weld metal of the T joint is, in mass%, C: 0.02 to 0.06%, Si: 0.40 to 0.80%, Mn: 0.80 to 1.70%, P: 0.020% or less, S: 0.010% or less, Ni: 7.00 to 13.00% Cr: 14.00 to 24.00% Cr: 14.00 to 24.00% N: 0.150% or less O: 0.050% or less
- the welded structure according to [1] having a composition with the balance being Fe and unavoidable impurities.
- the welded structure according to [1] or [2], wherein the member to be joined has a butt-welded joint portion so as to intersect the member to be joined.
- the joining member has a butt-welded joint portion, and the joining member is arranged so that the butt-welded joint portion and the butt-welded joint portion of the member to be welded intersect. 3].
- the non-welded portion has a gap of 10 mm or less between the butting surfaces of the member to be joined and the member to be joined.
- brittle crack propagation arrestability can be improved simply by selecting welding materials and adjusting welding conditions during welding without using special steel materials and without compromising safety. There is also an effect that an excellent welded structure can be manufactured.
- FIG. 4 is an explanatory diagram schematically showing an example of the configuration of a joint cross section of a T-joint;
- FIG. 4 is an explanatory diagram schematically showing another example of the configuration of the T-joint;
- (a) is an external view, and
- (b) is a sectional view.
- FIG. 4 is an explanatory diagram schematically showing another example of the configuration of the T-joint;
- (a) is an external view, and (b) is a sectional view.
- FIG. 4 is an explanatory diagram showing an example of a groove shape of a T-joint;
- the end face of the joining member 1 is butted against the surface of the member 2 to be joined, and the member 1 and the member 2 to be welded are joined. Equipped with a T-joint.
- the welded structure of the present invention is, for example, a hull structure in which the hull plate of a ship is a member to be joined (flange) and a bulkhead is a member to be joined (web), or a deck is a member to be joined (flange) and a hatch is applicable to hull structures where is a joint member (web).
- the material to be joined 2 is a thick steel plate with a plate thickness of 50 mm or more, preferably 60 mm or more and 120 mm or less.
- the joining member 1 is preferably made of a thick steel plate having a plate thickness of 50 mm or more, preferably 60 mm or more and 120 mm or less.
- the T-joint included in the welded structure of the present invention has weld metal 5, and its weld leg length 3 or weld width 13 is 16 mm or more.
- the non-welded portion 4 (the width 16 of the unwelded portion), which is a structural discontinuity that is not welded, is formed on the butting surfaces of the joining member 1 and the member to be joined 2.
- the T joint It is preferable that the size of the cross section is 30% or more of the plate thickness of the joining member 1 .
- the presence of the unwelded portion 4 makes it easier for the brittle crack that has propagated through the member to be joined 2 to stop at the butt surfaces.
- FIG. 1 shows a case where the member 1 to be joined is upright and joined to the member 2 to be joined, the present invention is not limited to this.
- the member 1 to be joined may be joined at an angle ⁇ with respect to the member 2 to be joined.
- the unwelded portion 4 may have a gap 14 between the joining member 1 and the joined member 2.
- a spacer 15 may be inserted into the gap 14.
- the gap 14 is preferably 10 mm or less from the viewpoint of reducing man-hours during welding.
- the size of the "gap" on the butting surfaces of the joined member and the non-joined member is the longest length at which the perpendicular line from the upper surface of the member to be joined intersects the end surface of the joined member in the cross-sectional view of the T joint perpendicular to the weld line. distance, including the spacer thickness if spacers are inserted. The same applies when the spacer is in contact with one or both selected from the end face of the joined member and the surface of the non-joined member.
- FIGS. 2 and 3 brittle cracks occur from the butt-welded joint 11 of the members to be joined.
- a structural discontinuity between the joining member 1 and the member to be joined 2 it is preferable to provide a structural discontinuity between the joining member 1 and the member to be joined 2.
- FIG. 4 as a discontinuous portion of the structure, an unwelded portion 4 having a dimension of 30% or more of the plate thickness of the joining member 1 is present on the butting surfaces of the joining member 2 and the joining member 1 of the T joint.
- the upper limit of the width (dimension) 16 of the unwelded portion 4 is 100% of the plate thickness of the joint member 1, preferably 40% or more, more preferably 50% or more, and 99% or less of the plate thickness of the joint member 1. is preferred, and 98% or less is preferred.
- the weld metal of the T-joint in addition to the presence of unwelded portions on the butt surfaces as structural discontinuities, the weld metal of the T-joint has excellent toughness, so that brittle crack propagation can be prevented more reliably.
- the member to be joined 2 is a steel plate joined by a butt welded joint 11, and the joined member 1 is a T joint welded so as to intersect the welded portion of the butt welded joint 11. Moreover, in the welded structure shown in FIG. and the butt welded joint 11 of the member to be joined 2 are welded so as to intersect each other.
- the joint member 1 and the butt-welded joint 11 are arranged orthogonally, but the present invention is not limited to this. Needless to say, they may cross each other obliquely.
- the manufacturing method of the T-joint is not particularly limited, and any conventional manufacturing method can be applied.
- a T-joint may be manufactured by butt-welding the steel plates for the members to be joined and the steel plates for the joining members, and welding the obtained butt-welded joints.
- a set of steel plates for joining members before butt welding is tack welded to the members to be joined, then the steel plates for joining members are butt welded together, and the obtained butt welded joint is finally welded to the members to be joined.
- a T-joint may be manufactured.
- the welded leg length 3 or welded width 13 of the T-joint shall be 16 mm or more. If the weld leg length 3 and the weld width 13 are less than 16 mm, it is advantageous to ensure brittle crack arrestability, but if the member plate thickness exceeds 80 mm, it becomes difficult to ensure the strength of the weld. Even if the thickness of the member is 80 mm or less, if the weld leg length 3 and the weld width 13 are less than 16 mm, there is a high risk that it will be difficult to secure the strength of the welded portion due to rework during construction. Although the upper limits of the weld leg length 3 and the weld width 13 are not particularly limited, they are preferably 30 mm or less from the viewpoint of work efficiency and the like.
- the structure of the weld metal of the T joint has an austenite phase of 80% or more, preferably 84% or more, more preferably 88% or more in terms of area%.
- a phase other than the austenite phase a ferrite phase having an area percentage of 0 to 20% can be exemplified. From the viewpoint of preventing solidification cracking, it is important to adjust the amount of ferrite in the weld metal based on the composition of the weld metal, for example, using a Schaeffler structure diagram.
- the weld metal having the above structure has a Vickers hardness of 170 to 260 HV (yield strength of 390 MPa or more, tensile strength of 490 MPa or more). It is preferred to have
- the toughness of the weld metal is improved. Propagation of a brittle crack generated in the joint member can be stopped by the weld metal of the fillet welded joint, and propagation of the brittle crack to the joint member can be prevented.
- the weld metal of the T joint having the above structure is, in mass%, C: 0.02 to 0.06%, Si: 0.40 to 0.80%, Mn: 0.80 to 1.70%, P: 0.020% or less, S: 0.010% or less. , Ni: 7.00 to 13.00%, Cr: 14.00 to 24.00%, N: 0.150% or less, O: 0.050% or less, and the balance is Fe and unavoidable impurities.
- C 0.02-0.06%
- C is an element that precipitates as carbides during welding and causes intergranular corrosion and pitting corrosion, which lowers corrosion resistance. In order to obtain such an effect, the content of 0.02% or more is required. However, when the content exceeds 0.06%, the corrosion resistance is lowered. Therefore, C is limited to the range of 0.02-0.06%. Incidentally, it is preferably 0.02 to 0.05%.
- Si acts as a deoxidizing agent and also contributes to increasing the strength of the weld metal.
- the content 0.40% or more is required.
- Si is limited to the range of 0.40-0.80%. Incidentally, it is preferably 0.40 to 0.70%.
- Mn 0.80-1.70%
- Mn is an element that acts as a deoxidizing agent and contributes to increasing the strength of the austenite phase, and is contained in an amount of 0.80% or more in the present invention.
- a content exceeding 1.70% causes embrittlement. Therefore, Mn is limited to the range of 0.80-1.70%. Incidentally, it is preferably 0.90 to 1.60%.
- P 0.020% or less
- P is an element that is unavoidably included, and segregates at grain boundaries to adversely affect hot cracking resistance, so it is desirable to reduce it as much as possible.
- P is limited to 0.020% or less. If P is 0.020% or less, a weld metal having excellent hot cracking resistance can be obtained.
- P is preferably 0.010% or less.
- S 0.010% or less S is an unavoidable element that segregates at grain boundaries and adversely affects hot cracking resistance, so it is desirable to reduce it as much as possible. However, excessive reduction leads to an increase in refining costs, so in the present invention S is limited to 0.010% or less. Incidentally, S is preferably 0.007% or less.
- Ni 7.00-13.00%
- Ni is an element that stabilizes the austenite phase, and the present invention requires a content of 7.00% or more. On the other hand, if the content exceeds 13.00%, the material cost will rise. Therefore, Ni is limited to the range of 7.00 to 13.00%. Incidentally, it is preferably 7.50 to 12.50%.
- Cr 14.00-24.00% Cr has the effect of improving the strength of the weld metal. In the present invention, if Cr is less than 14.00%, the above effects cannot be sufficiently secured. On the other hand, if the content exceeds 24.00%, the toughness and hot cracking resistance of the weld metal are lowered. Therefore, Cr is limited to the range of 14.00-24.00%. Incidentally, it is preferably 14.50 to 23.50%.
- N 0.150% or less
- N is an element that is unavoidably contained, but it is an element that has the effect of increasing the strength of the weld metal in a solid solution state, and it is desirable to contain 0.003% or more.
- an excessive content lowers the toughness. Therefore, N is limited to a range of 0.150% or less. Incidentally, it is preferably 0.003 to 0.120%.
- O 0.050% or less
- O (oxygen) is an element that is unavoidably mixed, forms Al-based oxides and Si-based oxides in the weld metal, and contributes to suppressing the coarsening of the solidified structure. Since such an effect becomes remarkable at a content of 0.003% or more, it is desirable to have a content of 0.003% or more. Therefore, O (oxygen) is limited to 0.050% or less. Incidentally, it is preferably 0.003 to 0.040%.
- the above components are the basic components, but in addition to these basic components, one or two elements selected from Nb: 0.10% or less and Ti: 0.10% or less are selected for the purpose of improving strength. More than one species can be selected and contained.
- the balance other than the above elements consists of Fe and unavoidable impurities.
- the weld metal of the T-joint having the composition and structure described above is preferably formed by performing multi-layer welding by adjusting the welding material and welding conditions so as to obtain the composition and structure described above. .
- the commonly used welding covered arc welding method and gas metal arc welding method are both suitable.
- the welding material commercial coated welding rods specified in JIS Z 3221, commercial solid wires specified in JIS Z 3321, and commercial flux-cored wires specified in JIS Z 3323 are all suitable. be. Needless to say, a solid wire adjusted to a desired composition may be used.
- the joining member 1 may be provided with a groove having a predetermined angle (for example, 40° or less).
- the member to be joined is a thick steel plate (base material only) (Fig. 4(a)) or a thick steel plate having a butt-welded joint (Figs. 4(b) and (c)), and the member to be joined is a thick steel plate (base material). material only) (Figs.
- Welding was performed using the gas metal arc welding method (GMAW) so that the weld metal had the composition shown in Table 1, the structure and hardness shown in Table 2, and the welding width or weld leg length.
- Welded joints (T joints) were prepared by changing welding conditions such as heat and shield gas.
- the welding material was a flux-cored wire with a diameter of 1.2 mm specified in JIS Z 3323.
- a gap 14 was provided between the joining member 1 and the member to be joined 2 .
- the joint member 1 was welded with a groove as shown in FIG.
- a test piece was taken from the weld metal of the obtained T-joint, and the composition of the weld metal was determined using an emission spectroscopic analysis method. Weld metal hardness was measured using a meter (load 0.3 to 1.0 kgf). Table 2 shows the results obtained.
- a super-large structural model specimen shown in Fig. 4 was produced, and a brittle crack arrest test was performed.
- a steel plate having the same thickness as the member to be joined 2 was welded below the member to be joined 2 of the large welded joint 9 by tack welding 8 .
- the mechanical notch 7 was hit to generate a brittle crack, and it was investigated whether or not the propagated brittle crack would stop at the weld metal. All tests were conducted under conditions of stress of 243 to 283 N/mm 2 and temperature of -10°C.
- the stress of 243 N/mm 2 is equivalent to the maximum allowable stress of 355 N/mm class 2 steel plate applied to the hull, and the stress of 257 N/mm 2 is the yield strength of 390 N/mm 2 applied to the hull.
- the stress of 283N/mm 2 is the value equivalent to the maximum allowable stress of class steel plates with a yield strength applied to ship hulls. Temperature: -10°C is the ship's design temperature.
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Abstract
Description
[1]接合部材の端面が板厚50mm以上の被接合部材の表面に突き合されて、前記接合部材と前記被接合部材とが接合されているT継手を具える、溶接構造体であって、
前記T継手の溶接脚長または溶着幅が16mm以上であり、または更に前記T継手における前記接合部材の端面と前記被接合部材の表面とを突き合わせた面に、該T継手の断面で前記接合部材の板厚の30%以上の未溶着部が存在し、
前記T継手の溶接金属が、面積%で80%以上のオーステナイト相を含む組織を有することを特徴とする、溶接構造体。
[2]前記T継手の溶接金属が、質量%で、C:0.02~0.06%、Si:0.40~0.80%、Mn:0.80~1.70%、P:0.020%以下、S:0.010%以下、Ni:7.00~13.00%、Cr:14.00~24.00%、N:0.150%以下、O:0.050%以下を含有し、残部Feおよび不可避的不純物からなる組成を有する、前記[1]に記載の溶接構造体。
[3]前記被接合部材が、前記接合部材と交差するように突合せ溶接継手部を有する、前記[1]または[2]に記載の溶接構造体。
[4]前記接合部材が、突合せ溶接継手部を有し、該突合せ溶接継手部と前記被溶接部材の突合せ溶接継手部とが交差するように、前記接合部材が配設されている、前記[3]に記載の溶接構造体。
[5]前記接合部材が、50mm以上の板厚を有する、前記[1]~[4]のいずれかに記載の溶接構造体。
[6]前記未溶着部が、前記接合部材と前記被接合部材との突き合わせ面に、10mm以下の隙間を有する、前記[1]~[5]のいずれかに記載の溶接構造体。
Cは、溶接時に炭化物として析出し、粒界腐食や孔食の発生を招き、耐食性を低下させる元素であるが、固溶強化により、溶接金属の強度を上昇させる作用をも有する。このような効果を得るためには、0.02%以上の含有を必要とする。しかし、0.06%を超えて含有すると、耐食性が低下する。そのため、Cは0.02~0.06%の範囲に限定した。なお、好ましくは、0.02~0.05%である。
Siは、脱酸剤として作用するとともに、溶接金属の強度増加にも寄与する。このような効果を得るためには、0.40%以上の含有を必要とする。しかし、0.80%を超えて含有すると、凝固時に偏析し、凝固セル界面に液相を生成して、耐高温割れ性を低下させる。さらには靭性が低下する。このため、Siは0.40~0.80%の範囲に限定した。なお、好ましくは0.40~0.70%である。
Mnは、脱酸剤として作用するとともに、オーステナイト相の強度増加に寄与する元素であり、本発明では0.80%以上含有する。一方、1.70%を超える含有は、脆化を招く。このため、Mnは0.80~1.70%の範囲に限定した。なお、好ましくは0.90~1.60%である。
Pは、不可避的に含まれる元素であり、粒界に偏析して耐高温割れ性に悪影響を及ぼすため、できるだけ低減することが望ましい。しかし、過度の低減は、精錬コストの増大を招くため、本発明ではPは0.020%以下に限定した。Pが0.020%以下であれば、耐高温割れ性に優れた溶接金属を確保できる。なお、好ましくはPは0.010%以下である。
Sは、不可避的に含まれる元素であり、粒界に偏析して耐高温割れ性に悪影響を及ぼすため、できるだけ低減することが望ましい。しかし、過度の低減は、精錬コストの増大を招くため、本発明ではSは0.010%以下に限定した。なお、好ましくはSは0.007%以下である。
Niは、オーステナイト相を安定化する元素であり、本発明では7.00%以上の含有を必要とする。一方、13.00%を超える含有は、材料費の高騰を招く。このため、Niは7.00~13.00%の範囲に限定した。なお、好ましくは7.50~12.50%である。
Crは、溶接金属の強度を向上させる効果がある。本発明では、Crが14.00%未満であると前記効果を十分に確保できない。一方、24.00%を超えて含有すると、溶接金属の靭性及び耐高温割れ性が低下する。このため、Crは14.00~24.00%の範囲に限定した。なお、好ましくは14.50~23.50%である。
Nは、不可避的に含有する元素であるが、固溶した状態で溶接金属の強度を高める効果を有する元素であり、0.003%以上含有することが望ましい。一方、過剰に含有すると、靭性が低下する。このため、Nは0.150%以下の範囲に限定する。なお、好ましくは0.003~0.120%である。
O(酸素)は、不可避的に混入する元素であり、溶接金属中で、Al系酸化物や、Si系酸化物を形成し、凝固組織の粗大化抑制に寄与する。このような効果は、0.003%以上の含有で著しくなるため、0.003%以上含有することが望ましいが、0.050%を超えて多量に含有すると、酸化物の粗大化が著しくなる。そのため、O(酸素)は0.050%以下に限定した。なお、好ましくは0.003~0.040%である。
2 被接合部材
3 溶接脚長
4 未溶着部
5 溶接金属
7 機械ノッチ
8 仮付け溶接
9 大型溶接継手
11 被接合部材の突合せ溶接継手
12 接合部材の突合せ溶接継手
13 溶着幅
14 隙間
15 スペーサー
16 未溶着部の寸法(未溶着部の幅)
Claims (6)
- 接合部材の端面が板厚50mm以上の被接合部材の表面に突き合されて、前記接合部材と前記被接合部材とが接合されているT継手を具える、溶接構造体であって、
前記T継手の溶接脚長または溶着幅が16mm以上であり、または更に前記T継手における前記接合部材の端面と前記被接合部材の表面とを突き合わせた面に、該T継手の断面で前記接合部材の板厚の30%以上の未溶着部が存在し、
前記T継手の溶接金属は、面積%で80%以上のオーステナイト相を含む組織を有することを特徴とする、溶接構造体。 - 前記T継手の溶接金属が、質量%で、C:0.02~0.06%、Si:0.40~0.80%、Mn:0.80~1.70%、P:0.020%以下、S:0.010%以下、Ni:7.00~13.00%、Cr:14.00~24.00%、N:0.150%以下、O:0.050%以下を含有し、残部Feおよび不可避的不純物からなる組成を有する、請求項1に記載の溶接構造体。
- 前記被接合部材が、前記接合部材と交差するように突合せ溶接継手部を有する、請求項1または2に記載の溶接構造体。
- 前記接合部材が、突合せ溶接継手部を有し、該突合せ溶接継手部と前記被溶接部材の突合せ溶接継手部とが交差するように、前記接合部材が配設されている、請求項3に記載の溶接構造体。
- 前記接合部材が、50mm以上の板厚を有する、請求項1~4のいずれか1項に記載の溶接構造体。
- 前記未溶着部が、前記接合部材と前記被接合部材との突き合わせ面に、10mm以下の隙間を有する、請求項1~5のいずれか1項に記載の溶接構造体。
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JP2007326147A (ja) * | 2006-05-12 | 2007-12-20 | Jfe Steel Kk | 脆性亀裂伝播停止特性に優れる溶接構造体 |
WO2013038685A1 (ja) * | 2011-09-13 | 2013-03-21 | Jfeスチール株式会社 | 溶接構造体 |
WO2017217516A1 (ja) * | 2016-06-16 | 2017-12-21 | Jfeスチール株式会社 | 脆性亀裂伝播停止特性に優れる溶接構造体 |
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WO2013038685A1 (ja) * | 2011-09-13 | 2013-03-21 | Jfeスチール株式会社 | 溶接構造体 |
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