WO2022265011A1 - Welded structure - Google Patents

Welded structure Download PDF

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Publication number
WO2022265011A1
WO2022265011A1 PCT/JP2022/023799 JP2022023799W WO2022265011A1 WO 2022265011 A1 WO2022265011 A1 WO 2022265011A1 JP 2022023799 W JP2022023799 W JP 2022023799W WO 2022265011 A1 WO2022265011 A1 WO 2022265011A1
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WO
WIPO (PCT)
Prior art keywords
welded
joined
less
butt
joint
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PCT/JP2022/023799
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French (fr)
Japanese (ja)
Inventor
涼太 長尾
恒久 半田
聡 伊木
Original Assignee
Ｊｆｅスチール株式会社
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Application filed by Ｊｆｅスチール株式会社 filed Critical Ｊｆｅスチール株式会社
Priority to JP2022560432A priority Critical patent/JP7195503B1/en
Priority to CN202280032210.1A priority patent/CN117241907A/en
Priority to KR1020237035722A priority patent/KR20230158578A/en
Publication of WO2022265011A1 publication Critical patent/WO2022265011A1/en

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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
    • B23K35/3053—Fe as the principal constituent
    • B23K35/3073—Fe as the principal constituent with Mn as next major constituent
    • 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
    • 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 (hereinafter also referred to as welded structures) that are welded using thick steel plates, such as large container ships and bulk carriers.
  • the present invention is a welded structure having excellent brittle crack arrestability, which can stop the propagation of brittle cracks generated from the base metal of a thick steel plate or the welded joint before it reaches a large-scale fracture 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 deviate from the weld zone toward the base metal due to the influence of welding residual stress.
  • multiple cases of brittle crack propagation along the weld have been confirmed. 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 applied in Non-Patent Document 1 to steel plates with a thickness of less than 50 mm are in service without any problems.
  • steel plate base material e.g. shipbuilding class E steel
  • the brittle crack arrestability of welded parts of shipbuilding steel is specifically required by ship classification rules. It hasn't been done.
  • Non-Patent Document 2 also 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 said that brittle fracture can be stopped at this time, and fatal damage such as destruction of the welded structure can be prevented.
  • Patent Literature 1 requires a complicated process to form the reinforcing material into a steel sheet having a desired structure. As a result, there is a problem that productivity is lowered and it is difficult to stably obtain a steel sheet having a desired structure.
  • 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 said to be adjusted so as to satisfy the crack arrestability Kca and a special relational expression.
  • the member to be joined is a thick material with a plate thickness of 50 mm or more
  • the propagation of brittle cracks generated in the member to be joined is stopped at the butt surface of the fillet weld, and the brittleness of the member to be joined is prevented. Propagation of cracks can be prevented.
  • the technique described in Patent Document 2 since the brittle crack propagation arresting properties of the joining members are insufficient, the technique is sufficient to stop the propagation of brittle cracks occurring in the joined members at the joining members. It can not be said.
  • Patent Documents 3 to 5 describe welded structures formed by abutting the end face of a joining member against the surface of a member to be joined and joining the member to be joined and the member to be joined by fillet welding.
  • an unwelded portion is provided on the surface where the end surface of the member to be joined and the surface of the member to be joined are butted, and at least one of the weld leg length and weld width is 16 mm or less.
  • a fillet welded joint in which the toughness of the fillet weld metal has a special relationship with the plate thickness of the member to be joined, or a steel plate with excellent brittle crack arrestability as the joint member.
  • the weld metal of the butt weld joint a welded structure with high toughness, brittle cracks generated from the welded part of the joined member , can be prevented from propagating at the welded portion of 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 Therefore, by using a fillet weld metal that has a toughness that satisfies the specified relationship, even if the plate thickness of the joint member is 65 to 120 mm, the fillet weld metal prevents the propagation of brittle cracks that occur in the member to be joined. It is said that it can be done.
  • Patent Document 7 describes a welded structure provided with 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 tabler member is overlap fillet welded to the flange, and the overlap is welded.
  • the welded structure has unwelded portions remaining on the mating surfaces. According to the technique described in Patent Document 7, 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 control during welding in order to limit the weld leg length and weld 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 processing and welding of the doubler member, and a problem that the material cost rises when an expensive austenitic steel plate is used 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 weld metal structure of the T-joint is made mainly of an austenite phase, the weld metal can be made to have high toughness.
  • 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 for joining the joint member and the joint member, wherein the end face of the joint member is butted against the surface of the joint member having a plate thickness of 50 mm or more, L, which is the longer value of the weld leg length and weld width of the T joint, is 16 mm or more,
  • the weld metal of the T joint is % by mass, C: 0.10-0.70%, Si: 0.10-1.00%, Mn: 15.00-28.00%, P: 0.030% or less, S: 0.015% or less, Ni: 1.00-5.00%, Cr: 0.50-4.00% , Mo: 2.00% or less, N: 0.150% or less and O: 0.050% or less, the balance being Fe and unavoidable impurities;
  • a welded structure having a weld metallographic structure in which the austenitic phase is 80% or more by area.
  • the composition of the weld metal further contains, in mass %, (a) one or more selected from V: 0.10% or less, Ti: 0.10% or less, and Nb: 0.10% or less; and (b) at least one selected from Cu: 1.00% or less, Al: 0.10% or less, Ca: 0.010% or less, and REM: 0.020% or less, [1] Welded structure according to. [3] In the T-joint, there is an unwelded portion on the surface where the end surface of the joining member and the surface of the member to be joined meet, and the ratio of the width of the unwelded portion to the plate thickness of the joining member The welded structure according to [1], wherein the unwelded ratio Y is 30% or more.
  • the joining member has a butt-welded joint portion, and the joining member is arranged so that the butt-welded joint portion of the joining member and the butt-welded joint portion of the member to be welded intersect.
  • the joining member has a butt-welded joint, and the joining member is arranged so that the butt-welded joint of the joining member and the butt-welded joint of the member to be welded intersect.
  • 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 a joint cross section of a T joint;
  • FIG. 4 is an explanatory diagram schematically showing another example of a T-joint;
  • (a) is an external view, and
  • (b) is a sectional view.
  • FIG. 4 is an explanatory diagram schematically showing another example of a T-joint;
  • (a) is an external view, and
  • (b) is a sectional view.
  • FIG. 4 is an explanatory diagram schematically showing the shape of a super-large structural model specimen;
  • FIG. 4 is an explanatory diagram showing an example of a groove shape of a T-joint;
  • a welded structure according to one embodiment of the present invention is a welded structure provided with a T-joint that joins the joining member 1 and the to-be-welded member 2 by abutting the end face of the joining member 1 against the surface of the to-be-joined member 2.
  • a welded structure according to an embodiment of the present invention is, for example, a hull structure in which a hull skin of a ship is a member to be joined and a bulkhead is a member to be joined, or a hull structure in which a deck is a member to be joined and a hatch is a member to be joined.
  • the T-joint described above has a joining member 1 , a member to be joined 2 , and a weld metal 5 .
  • the member to be joined 2 to be used is 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 joining member 1 is preferably made of a thick steel plate having a thickness of 50 mm or more, more preferably 60 mm or more and 120 mm or less.
  • the steel type of the thick steel plate used for the joining member 1 and the joined member 2 is not particularly limited, and for example, a thick steel plate having a yield strength of 350 to 490 N/mm 2 (MPa) can be suitably used.
  • the T-joint provided in the welded structure according to one embodiment of the present invention has weld metal 5, and L, which is the longer one of weld leg length 3 and weld width 13, is set to 16 mm or more.
  • the non-welded portion 4 (the width 16 of the unwelded portion), which is a structural discontinuity, is present on the butting surfaces of the joining member 1 and the member to be joined 2. good too.
  • the presence of the unwelded portion 4 makes it easier for the brittle crack that has propagated through the members to be joined 2 to stop at the butt surfaces.
  • the upper limit of the unwelded ratio Y is not particularly limited, the unwelded ratio Y is preferably 98% or less from the viewpoint of ensuring a predetermined strength.
  • the welded leg length 3, the welded width 13, and the width 16 of the unwelded portion are the joint cross section of the T joint (the joint cross section shown in FIG. 1, which will be described later). , which is a plane parallel to the xy plane when the plate thickness direction of the member 2 to be joined is taken as the y axis.
  • FIG. 1(a) shows a case where the member to be joined 1 is joined upright to the member to be joined 2, the present invention is not limited to this.
  • the joining member 1 may be joined at an angle ⁇ with respect to the member 2 to be joined.
  • a gap 14 may be provided between the member to be joined 1 and the member to be joined 2, and a spacer 15 may be inserted into the gap 14 as shown in FIG. 1(d).
  • the gap 14 is preferably 10 mm or less from the viewpoint of reducing man-hours during welding.
  • brittle cracks are generated from the butt-welded joint portion 11 .
  • a structural discontinuity As a discontinuous portion of the structure, for example, as described above, it is preferable to have an unwelded portion 4 on the butting surfaces of the joined member 2 and the joining member 1 of the T-joint.
  • the welded structure shown in FIG. 2 is a welded structure in which the member to be joined 2 is a steel plate joined by a butt weld joint 11, and the joint member 1 is welded so as to intersect the welded portion 11 of the butt weld joint. .
  • the joint member 1 is a steel plate joined by a butt weld joint 12
  • the member to be joined 2 is a steel plate joined by a butt weld joint 11
  • the butt weld joint 12 of the joint member 1 is used.
  • 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 so as to be perpendicular to each other, but the present invention is not limited to this. Needless to say, they may cross each other obliquely.
  • the method for manufacturing the welded joint is not particularly limited, and any commonly used manufacturing method can be applied. For example, steel plates for members to be joined and steel plates for members to be joined are butt-welded to obtain joining members and members to be joined having butt-welded joints. Then, the obtained joining member and the member to be joined may be welded to produce a T-joint.
  • a set of steel plates for joining members before butt welding is tack-welded to a member to be joined, and then the steel plates for joining members are butt-welded to each other to obtain a joining member having a butt-welded joint. Then, the obtained joining member may be permanently welded to the member to be joined to manufacture a T-joint.
  • L which is the longer value of the weld leg length 3 and the weld width 13 of the T-joint, shall be 16 mm or more. If L is less than 16 mm, that is, both the weld leg length 3 and the weld width 13 are less than 16 mm, it is advantageous to ensure brittle crack arrestability. However, when the member plate thickness exceeds 80 mm, it becomes difficult to ensure the strength of the welded portion. In addition, even if the plate thickness of the member is 80 mm or less, 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 limit of L is not particularly limited, L is preferably 30 mm or less from the viewpoint of construction efficiency and the like.
  • the structure of the weld metal of the T-joint is a structure in which the austenite phase is 80% or more in terms of area% (area ratio). .
  • the upper limit of the austenite phase is not particularly limited, and may be 100% in terms of area %.
  • a phase other than the austenite phase (hereinafter also referred to as the residual phase) is 0 to 20% in terms of area %, and examples of the residual phase include ferrite phase and the like.
  • the weld metal structure By setting the weld metal structure to a structure in which the austenite phase is 80% or more in area%, the toughness of the weld metal is improved. As a result, even when L is 16 mm or more, the propagation of brittle cracks generated in the members to be joined can be stopped by the weld metal of the T-joint, and the propagation of brittle cracks to the members to be joined can be prevented.
  • 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 mass % of the weld metal of the T joint is C: 0.10 to 0.70%, Si: 0.10 to 1.00%, Mn: 15.00 to 28.00%, P: 0.030% or less, S: 0.015% or less, Ni: 1.00% or more.
  • the balance consists of Fe and unavoidable impurities.
  • the toughness of the weld metal is improved by setting the weld metal structure to a structure in which the austenite phase is 80% or more in terms of area %.
  • L is 16 mm or more
  • the propagation of brittle cracks generated in the members to be joined can be stopped by the weld metal of the T-joint, and the propagation of brittle cracks to the members to be joined can be prevented.
  • mass % in the weld metal composition is simply expressed as %.
  • C 0.10-0.70%
  • C is an element that stabilizes austenite.
  • C is an element that has the effect of increasing the strength of the weld metal through solid-solution strengthening.
  • the C content must be 0.10% or more.
  • the C content should be 0.10-0.70%.
  • the C content is preferably 0.20-0.60%.
  • Si 0.10-1.00% Si suppresses the precipitation of carbides, causes C to dissolve in austenite, and stabilizes austenite.
  • the content of Si must be 0.10% or more.
  • Si content exceeds 1.00%, Si segregates during solidification to form a liquid phase at solidification cell interfaces. This reduces hot cracking resistance. Furthermore, the toughness is lowered. Therefore, the Si content should be 0.10 to 1.00%.
  • the Si content is preferably 0.20 to 0.90%.
  • Mn 15.00-28.00%
  • Mn is an element that stabilizes the austenite phase at low cost.
  • the content of Mn is required to be 15.00% or more. If the Mn content is less than 15.00%, the stability of austenite is insufficient. As a result, a hard martensite phase is generated in the weld metal and the toughness is lowered. On the other hand, if the Mn content exceeds 28.00%, excessive Mn segregation occurs during solidification, which induces hot cracking. Therefore, the Mn content should be 15.00-28.00%.
  • the Mn content is preferably 17.00-26.00%.
  • P 0.030% or less
  • P is an element that segregates at grain boundaries and induces hot cracking. Therefore, it is preferable to reduce P as much as possible, but 0.030% or less is permissible. Therefore, the P content should be 0.030% or less. Excessive reduction of P invites an increase in refining cost. Therefore, it is preferable to adjust the P content to 0.002% or more.
  • S 0.015% or less S is an element that segregates at grain boundaries and induces hot cracking. Therefore, it is preferable to reduce S as much as possible, but 0.015% or less is permissible. Therefore, the S content should be 0.015% or less. Note that an excessive reduction in S causes an increase in refining costs. Therefore, it is preferable to adjust the S content to 0.001% or more.
  • Ni 1.00-5.00%
  • Ni is an element that strengthens austenite grain boundaries, and by suppressing embrittlement of grain boundaries, suppresses the occurrence of hot cracks. In order to obtain such effects, the content of Ni must be 1.00% or more. Ni also has the effect of stabilizing the austenite phase. However, Ni is an expensive element, and a Ni content exceeding 5.00% is economically disadvantageous. Therefore, the Ni content should be 1.00 to 5.00%.
  • Cr 0.50-4.00% Cr has the effect of improving the strength of the weld metal. If the Cr content is less than 0.50%, the above effects cannot be secured. On the other hand, when the Cr content exceeds 4.00%, the toughness and hot cracking resistance of the weld metal deteriorate. Therefore, the Cr content should be 0.50 to 4.00%. The Cr content is preferably 0.70-3.00%.
  • Mo is an element that strengthens austenite grain boundaries, and by suppressing embrittlement of grain boundaries, suppresses the occurrence of hot cracks. Mo also has the effect of improving wear resistance by hardening the weld metal. In order to obtain such effects, the Mo content is preferably 0.10% or more. On the other hand, if the Mo content exceeds 2.00%, the grain interiors are too hardened, the grain boundaries become relatively weak, and hot cracking occurs. Therefore, the Mo content should be 2.00% or less. Incidentally, the Mo content is more preferably 0.20 to 1.90%.
  • N 0.150% or less
  • N is an element that is unavoidably mixed.
  • N like C, effectively contributes to improving the strength of the weld metal.
  • N is also an element that stabilizes the austenite phase and stably improves the cryogenic toughness. Since such an effect becomes remarkable when the N content is 0.003% or more, the N content is preferably 0.003% or more.
  • the N content exceeds 0.150%, nitrides are formed and the low temperature toughness is lowered. Therefore, the N content should be 0.150% or less.
  • the N content is preferably 0.003-0.120%.
  • O 0.050% or less
  • O (oxygen) is an unavoidable element. However, O forms Al-based oxides and Si-based oxides in the weld metal and contributes to suppression of coarsening of the solidified structure. Since such an effect becomes significant when the O content is 0.003% or more, the O content is preferably 0.003% or more. However, when the O content exceeds 0.050%, coarsening of the oxide becomes significant. Therefore, the O (oxygen) content should be 0.050% or less. The O content is preferably 0.003-0.040%.
  • components described above are the basic components of the weld metal composition, but in addition to the basic components described above, optional components include: (a) one or more selected from V: 0.10% or less, Ti: 0.10% or less, and Nb: 0.10% or less; and (b) at least one selected from Cu: 1.00% or less, Al: 0.10% or less, Ca: 0.010% or less, and REM: 0.020% or less.
  • V 0.10% or less
  • Ti 0.10% or less
  • Nb 0.10% or less It is an element that precipitates carbides and contributes to an increase in the strength of the weld metal, and one or more of these elements can be optionally contained.
  • V 0.10% or less
  • V is a carbide-forming element that precipitates fine carbides in grains and contributes to improving the strength of the weld metal.
  • the V content is preferably 0.10% or less.
  • the V content is more preferably 0.002-0.050%.
  • Ti 0.10% or less
  • Ti is a carbide-forming element, which precipitates fine carbides and contributes to improving the strength of the weld metal.
  • the Ti content is preferably 0.10% or less.
  • the Ti content is more preferably 0.002 to 0.050%.
  • Nb 0.10% or less Like V and Ti, Nb is also a carbide-forming element that precipitates fine carbides and contributes to improving the strength of the weld metal. In order to obtain such effects, it is preferable to contain 0.001% or more of Nb. However, if the Nb content exceeds 0.10%, excessive carbides act as starting points for fractures, resulting in a decrease in low-temperature toughness. Therefore, when Nb is contained, the Nb content is preferably 0.10% or less. The Nb content is more preferably 0.002-0.090%.
  • Cu is an element that contributes to austenite stabilization.
  • Al is an element that acts as a deoxidizing agent.
  • Ca and REM are elements that contribute to the suppression of hot cracking.
  • Cu, Al, Ca and REM can optionally contain one or more.
  • Cu 1.00% or less
  • Cu is an element that stabilizes the austenite phase. In order to obtain such effects, it is preferable to contain 0.01% or more of Cu. However, when the Cu content exceeds 1.00%, a liquid phase with a low melting point is generated at the grain boundary, resulting in hot cracking. Therefore, when Cu is contained, the Cu content is preferably 1.00% or less. The Cu content is more preferably 0.02-0.80%.
  • Al acts as a deoxidizing agent. Also, Al has an important effect of increasing the viscosity of the molten metal, stably maintaining the bead shape, and reducing the occurrence of spatter. Furthermore, Al reduces the solid-liquid coexistence temperature range and contributes to suppressing the occurrence of hot cracks in the weld metal. Since such an effect becomes remarkable when the Al content is 0.001% or more, the Al content is preferably 0.001% or more. However, if the Al content exceeds 0.10%, the viscosity of the molten metal becomes too high, and conversely, spatter increases and defects such as poor fusion increase without bead spreading. Therefore, when Al is contained, the Al content is preferably 0.10% or less. The Al content is more preferably 0.002-0.090%.
  • Ca 0.010% or less Ca is an element that contributes to the suppression of hot cracking.
  • Ca combines with S in the molten metal to form sulfide CaS with a high melting point, thereby suppressing hot cracking.
  • the Ca content is preferably 0.010% or less.
  • the Ca content is more preferably 0.002 to 0.008%.
  • REM 0.020% or less REM, like Ca, is an element that contributes to the suppression of hot cracking.
  • REM is also a strong deoxidizing agent and exists in the form of REM oxides in the weld metal. REM oxides act as nucleation sites during solidification, thereby changing the solidification morphology of the weld metal and contributing to the suppression of hot cracking. Such an effect becomes remarkable when the content of REM is 0.001% or more.
  • the REM content exceeds 0.020%, arc stability decreases. Therefore, when REM is contained, the REM content is preferably 0.020% or less.
  • the REM content is more preferably 0.002-0.016%.
  • the balance other than the above components is Fe and unavoidable impurities.
  • unavoidable impurities include Bi, Sn, Sb, etc., and a total content of 0.2% or less is permissible.
  • weld metal of the T-joint having the above weld metal composition and the above weld metal structure can be formed, for example, by adjusting the welding material and welding conditions and performing multi-layer welding.
  • gas metal arc welding which is commonly used, is suitable.
  • the solid wire to be used has the above-described weld metal composition and the above-described weld metal structure so that the weld metal of the T-joint can be formed.
  • % by mass C: 0.10-0.70%, Si: 0.10-1.00%, Mn: 15.00-28.00%, P: 0.030% or less, S: 0.015% or less, Ni: 1.00-5.00%, Cr: 0.50-4.00% , Mo: 2.00% or less, N: 0.150% or less, and O: 0.050% or less, optionally, (a) one or more selected from V: 0.10% or less, Ti: 0.10% or less, and Nb: 0.10% or less; and (b) Cu: 1.00% or less, Al: 0.10% or less, Ca: 0.010% or less, and REM: 0.020% or less.
  • the wire preferably has a wire composition in which the balance is Fe and unavoidable impurities.
  • gas metal arc welding is preferably performed in a shielding gas to form a multi-layer weld metal.
  • the welding conditions are downward position, current: 150 to 450 A (DCEP), voltage: 20 to 40 V, welding speed: 15 to 60 cm/min, interpass temperature: 100 to 200°C, and shield gas: 80 volumes. It is preferable to satisfy the conditions of %Ar-20% by volume CO 2 at the same time.
  • the welding heat input for one pass within the range of 1.0 to 3.0 kJ/mm.
  • the joining member 1 may be provided with a groove having a predetermined angle (40°).
  • the end surface of the member to be joined 1 is butted against the surface of the member to be joined 2, and these are welded to produce a large welded joint 9 of the actual size having the shape shown in FIGS. did.
  • the member to be joined is a thick steel plate (only the base material, the type in Table 2 is indicated as "base material”) (Fig.
  • Welding of the joining member 1 and the member to be joined 2 was performed by gas metal arc welding (GMAW) so that the weld metal composition shown in Table 1 and the weld metal structure, hardness and L shown in Table 2 were obtained.
  • welding materials, and welding conditions such as welding heat input and shielding gas were varied to fabricate T-joints.
  • the welding consumable was a solid wire with a diameter of 1.2 mm adjusted to the desired weld metal composition.
  • the welding conditions are downward position, current: 150 to 450A (DCEP), voltage: 20 to 40V, welding speed: 15 to 60cm/min, interpass temperature: 100 to 200°C, shield gas: 80% by volume Ar.
  • the condition was -20 vol% CO 2 .
  • the heat input for one-pass welding was adjusted within the range of 1.0 to 3.0 kJ/mm.
  • a gap 14 was provided between the joining member 1 and the joined member 2.
  • the joining 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. Using the sampled test piece, a chemical analysis method according to a conventional method was performed to measure the composition of the weld metal. Table 2 shows the results.
  • the austenite phase and ferrite phase were identified by phase analysis by the EBSD method according to the usual method, and the area ratio of each phase in the weld metal structure was calculated. Table 2 shows the results.
  • weld metal hardness was measured according to JIS Z 2244-1 (2020) using the sampled test pieces. Table 2 shows the results.
  • 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 .
  • a mechanical notch 7 is provided in the member 2 to be joined.
  • brittle crack arrest test the machine notch 7 was hit to generate a brittle crack, and it was investigated whether the propagated brittle crack would stop at the weld metal (WM). 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/ mm2 is the value equivalent to the maximum allowable stress of class steel plates with a yield strength applied to ship hulls. It was set to correspond to the maximum allowable stress depending on the The temperature of -10°C is the design temperature for ships.
  • the brittle crack propagated through the joined member 2 and then entered the weld metal 5 and stopped.
  • the brittle crack propagated to the joint member 1 without stopping at the weld metal 5 .
  • weld metal 5 could not prevent the propagation of brittle cracks.

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Abstract

A welded structure comprising a T-joint in which an end surface of a welding member is butted against a surface of a member that is to be welded and has a plate thickness of 50 mm or greater, thereby joining the welding member and the member to be welded, the weld metal of the T-joint having a prescribed weld metal composition and a weld metal structure in which the austenite phase is at least 80% by area.

Description

溶接構造体Welded structure
　本発明は、例えば、大型コンテナ船やバルクキャリアーなどの、厚鋼板を用いて溶接施工された溶接鋼構造物（以下、溶接構造体ともいう）に関する。本発明は、特に、厚鋼板の母材または溶接継手部から発生した脆性亀裂の伝播を、構造物の大規模破壊に至る前に停止させることができる、脆性亀裂伝播停止特性に優れる溶接構造体に関する。 The present invention relates to welded steel structures (hereinafter also referred to as welded structures) that are welded using thick steel plates, such as large container ships and bulk carriers. In particular, the present invention is a welded structure having excellent brittle crack arrestability, which can stop the propagation of brittle cracks generated from the base metal of a thick steel plate or the welded joint before it reaches a large-scale fracture of the structure. Regarding.
　コンテナ船やバルクキャリアーは、積載能力の向上や荷役効率の向上等のため、例えば、タンカー等とは異なり、船上部の開口部を大きくとった構造を有している。そのため、コンテナ船やバルクキャリアーでは、特に船体外板を、高強度化または厚肉化する必要がある。 Unlike tankers, for example, 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.
　また、コンテナ船は、近年、大型化し、6,000～24,000TEUといった大型船が建造されるようになってきている。なお、TEU（Twenty feet Equivalent Unit）は、長さ20フィートのコンテナに換算した個数を表し、コンテナ船の積載能力の指標を示す。このような船の大型化に伴い、船体外板は、板厚：50mm以上で、降伏強さ：390Ｎ/mm2級以上の厚鋼板が使用される傾向となっている。 In addition, container ships have become larger in recent years, and large ships of 6,000 to 24,000 TEU are being built. TEU (Twenty Feet Equivalent Unit) represents the number of containers converted into 20-foot-long containers, and is an indicator of the loading capacity of container ships. Along with the increase in size of ships, there is a tendency to use thick steel plates having a plate thickness of 50 mm or more and a yield strength of 390 N/mm 2 class or more for the hull shell plates.
　船体外板となる鋼板は、近年、施工期間の短縮という観点から、例えばエレクトロガスアーク溶接等の大入熱溶接により突合せ溶接されることが多い。このような大入熱溶接は、溶接熱影響部での大幅な靭性低下に繋がりやすく、溶接継手部からの脆性亀裂発生の一つの原因となっていた。 In recent years, 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. Such 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.
　一方、船体構造においては、従来から安全性という観点から、万一、脆性破壊が発生した場合でも、脆性亀裂の伝播を大規模破壊に至る前に停止させ、船体分離を防止することが必要であると考えられている。 On the other hand, in the hull structure, from the viewpoint of safety, even in the event that brittle fracture occurs, it is necessary to stop the propagation of brittle cracks before they reach a large scale and prevent hull separation. It is believed that there are
　このような考え方を受けて、非特許文献１に、板厚50mm未満の造船用鋼板における溶接部の脆性亀裂伝播挙動についての実験的な検討結果が報告されている。 Based on this idea, 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.
　非特許文献１には、溶接部で強制的に発生させた脆性亀裂の伝播経路、および伝播挙動が実験的に調査されている。ここには、溶接部の破壊靱性がある程度確保されていれば、溶接残留応力の影響により脆性亀裂は溶接部から母材側に逸れてしまうことが多いという結果が記載されている。ただし、溶接部に沿って脆性亀裂が伝播した例も複数例確認されている。このことは、脆性破壊が溶接部に沿って直進伝播する可能性が無いとは言い切れないことを示唆していることになる。 In 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 deviate from the weld zone toward the base metal due to the influence of welding residual stress. However, multiple cases of brittle crack propagation along the weld have been confirmed. This suggests that the possibility of brittle fracture propagating straight along the weld cannot be ruled out.
　しかしながら、非特許文献１で適用した溶接と同等の溶接を板厚50mm未満の鋼板に適用して建造された船舶が何ら問題なく就航しているという多くの実績があることに加え、靱性が良好な鋼板母材（造船Ｅ級鋼など）は脆性亀裂を停止する能力を十分に保持しているとの認識から、造船用鋼材の溶接部の脆性亀裂伝播停止特性は、船級規則等では特に要求されてこなかった。 However, there are many achievements that ships built by applying welding equivalent to the welding applied 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 steel plate base material (e.g. shipbuilding class E steel) possesses sufficient ability to stop brittle cracks, the brittle crack arrestability of welded parts of shipbuilding steel is specifically required by ship classification rules. It hasn't been done.
　また、近年の6,000TEUを超える大型コンテナ船では、使用する鋼板の板厚が50mmを超える場合がある。この場合、板厚増大による破壊靱性の低下に加え、溶接入熱がより大きな大入熱溶接の採用により、溶接部の破壊靭性が一層低下する傾向にある。このような板厚が50mmを超える鋼板に対して大入熱溶接を施して得られる厚肉大入熱溶接継手では、溶接部から発生した脆性亀裂が、母材側に反れずに直進し、また骨材等の鋼板母材部でも停止しない可能性がある。この点は、例えば、非特許文献２に示されている。このため、板厚50mm以上の厚肉高強度鋼板を適用した船体構造の安全性確保が、大きな問題となっている。また、非特許文献２には、発生した脆性亀裂の伝播停止のために、特別な脆性亀裂伝播停止特性を有する厚鋼板を必要とするとの指摘もある。 In addition, in recent years, large container ships exceeding 6,000 TEU may use steel plates with thicknesses exceeding 50 mm. In this case, in addition to the decrease in fracture toughness due to the increase in plate thickness, there is a tendency for the fracture toughness of the weld zone to decrease further due to the adoption of high heat input welding with a higher welding heat input. In thick-wall, high-heat-input welded joints obtained by applying high-heat-input welding to steel plates with a thickness of more than 50 mm, brittle cracks generated from the weld go straight to the base metal side without warping, Also, there is a possibility that the steel plate base material such as aggregate may not stop. This point is shown in Non-Patent Document 2, for example. Therefore, ensuring the safety of the hull structure using thick high-strength steel plates with a thickness of 50 mm or more has become a major issue. In addition, Non-Patent Document 2 also 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.
　このような問題に対し、例えば、特許文献１には、好ましくは板厚50mm以上の船殻外板である溶接構造体において、突合せ溶接部に交差するように骨材を配置し、隅肉溶接で接合した溶接構造体が記載されている。特許文献１に記載された技術では、所定のミクロ組織を有する鋼板を補強材として隅肉溶接した構造とすることにより、突合せ溶接継手部に脆性亀裂が発生しても、補強材である骨材で脆性破壊を停止でき、溶接構造体が破壊するような致命的な損傷を防止できるとしている。しかし、特許文献１に記載された技術では、補強材を、所望の組織を形成させた鋼板とするために複雑な工程を必要とする。その結果、生産性が低下し、安定して所望の組織を有する鋼板を確保することが難しいという問題があった。 In order to solve such a problem, for example, 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 said that brittle fracture can be stopped at this time, and fatal damage such as destruction of the welded structure can be prevented. However, the technique described in Patent Literature 1 requires a complicated process to form the reinforcing material into a steel sheet having a desired structure. As a result, there is a problem that productivity is lowered and it is difficult to stably obtain a steel sheet having a desired structure.
　また、特許文献２には、接合部材を被接合部材に隅肉溶接してなる隅肉溶接継手を備える溶接構造体が記載されている。特許文献２に記載された溶接構造体では、隅肉溶接継手断面における接合部材の、被接合部材との突合せ面に未溶着部を残存させ、その未溶着部の幅を、被接合部材の脆性亀裂伝播停止性能Kcaと特別な関係式を満足するように調整するとしている。これにより、被接合部材（フランジ）を板厚：50mm以上の厚物材としても、接合部材で発生した脆性亀裂の伝播を、隅肉溶接部の突合せ面で停止させ、被接合部材への脆性亀裂の伝播を阻止することができるとしている。しかし、特許文献２に記載された技術では、接合部材の脆性亀裂伝播停止特性等が不十分であるため、被接合部材で発生した脆性亀裂を接合部材で伝播停止させるにたる十分な技術であるとは言えない。 In addition, 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. In the welded structure described in Patent Document 2, 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 said to be adjusted so as to satisfy the crack arrestability Kca and a special relational expression. As a result, even if the member to be joined (flange) is a thick material with a plate thickness of 50 mm or more, the propagation of brittle cracks generated in the member to be joined is stopped at the butt surface of the fillet weld, and the brittleness of the member to be joined is prevented. Propagation of cracks can be prevented. However, in the technique described in Patent Document 2, since the brittle crack propagation arresting properties of the joining members are insufficient, the technique is sufficient to stop the propagation of brittle cracks occurring in the joined members at the joining members. It can not be said.
　また、特許文献３～５には、接合部材の端面を被接合部材の表面に突合わせ、接合部材と被接合部材とを隅肉溶接により接合してなる溶接構造体が記載されている。特許文献３～５に記載された技術では、接合部材の端面と被接合部材の表面とを突合わせた面に未溶着部を備え、かつ溶接脚長もしくは溶着幅の少なくとも一方が16mm以下の隅肉溶接継手としたうえで、隅肉溶接金属の靭性が被接合部材の板厚との関係で特別な関係を有する隅肉溶接継手とし、あるいはさらに接合部材を脆性亀裂伝播停止性能に優れた鋼板としたり、突合せ溶接継手の溶接金属を高靭性とした溶接構造体とすることにより、被接合部材溶接部から発生した脆性亀裂を、隅肉溶接部で、あるいは接合部材の母材で、または接合部材、被接合部材の溶接部で、伝播阻止することができるとしている。 In addition, Patent Documents 3 to 5 describe welded structures formed by abutting the end face of a joining member against the surface of a member to be joined and joining the member to be joined and the member to be joined by fillet welding. In the techniques described in Patent Documents 3 to 5, an unwelded portion is provided on the surface where the end surface of the member to be joined and the surface of the member to be joined are butted, and at least one of the weld leg length and weld width is 16 mm or less. After making a welded joint, a fillet welded joint in which the toughness of the fillet weld metal has a special relationship with the plate thickness of the member to be joined, or a steel plate with excellent brittle crack arrestability as the joint member. Or, by making the weld metal of the butt weld joint a welded structure with high toughness, brittle cracks generated from the welded part of the joined member , can be prevented from propagating at the welded portion of the member to be joined.
　しかし、特許文献３～５に記載された各技術では、溶接脚長（または溶着幅）を16mm以下に制限する必要があり、そのため、隅肉溶接部の強度確保の観点から、接合部材（ウェブ）および被接合部材（フランジ）に適用できる板厚は最大でも80mmであった。 However, in each technique described in Patent Documents 3 to 5, it is necessary to limit the weld leg length (or weld width) to 16 mm or less. And the plate thickness that can be applied to the member to be joined (flange) was 80 mm at maximum.
　このような問題に対し、例えば、特許文献６には、接合部材の端面が板厚50mm以上の被接合部材の表面に突合わされ、また接合部材と被接合部材とを接合する隅肉溶接継手を備える溶接構造体が記載されている。特許文献６に記載された溶接構造体は、隅肉溶接継手の溶接脚長および溶着幅が16mm超えで、隅肉溶接継手における接合部材の端面と被接合部材の表面とを突合わせた面に、隅肉溶接継手の断面で該接合部材の板厚twの95％以上の未溶着部を有し、さらに、溶接脚長および溶着幅のうちの小さい方の値Ｌと被接合部材の板厚tfとの関係で、所定の関係を満足する靭性を有する隅肉溶接金属とすることにより、接合部材の板厚を65～120mmとしても、被接合部材で発生した脆性亀裂を隅肉溶接金属で伝播阻止することができるとしている。 In response to such problems, for example, 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 Therefore, by using a fillet weld metal that has a toughness that satisfies the specified relationship, even if the plate thickness of the joint member is 65 to 120 mm, the fillet weld metal prevents the propagation of brittle cracks that occur in the member to be joined. It is said that it can be done.
　また、特許文献７には、ウェブとフランジの突合せ部分にダブラー部材を備える溶接構造体が記載されている。特許文献７に記載された溶接構造体は、ウェブがダブラー部材に突合せ隅肉溶接され、該突合せ面に未溶着部が残存し、さらに、タブラー部材がフランジに重ね合わせ隅肉溶接され、該重ね合わせ面に未溶着部が残存する溶接構造体としている。特許文献７に記載された技術では、ダブラー部材にオーステナイト鋼板を使用すれば、長大脆性亀裂の伝播をダブラー部材で阻止することができるとしている。 In addition, Patent Document 7 describes a welded structure provided with a doubler member at the butted portion of the web and flange. In the welded structure described in Patent Document 7, the web is butt fillet welded to the doubler member, an unwelded portion remains on the butt surface, and the tabler member is overlap fillet welded to the flange, and the overlap is welded. The welded structure has unwelded portions remaining on the mating surfaces. According to the technique described in Patent Document 7, if an austenitic steel plate is used for the doubler member, propagation of long brittle cracks can be prevented by the doubler member.
特開2004－232052号公報Japanese Patent Application Laid-Open No. 2004-232052 特開2007－326147号公報Japanese Patent Application Laid-Open No. 2007-326147 特許第5395985号Patent No. 5395985 特許第5365761号Patent No. 5365761 特許第5408396号Patent No. 5408396 特許第6744274号Patent No. 6744274 特許第6615215号Patent No. 6615215
　しかしながら、特許文献６に記載された技術では、溶接脚長や溶着幅を制限するために溶接時の厳格な施工管理が必須であり、溶接施工の生産性低下や施工費用の増大が問題であった。加えて、未溶着部の小さい部分溶込み溶接が要求される構造において、十分な脆性亀裂伝播停止性能を確保できないという問題があった。また、特許文献７に記載された技術では、ダブラー部材加工・溶接により施工コストが増加するという問題や、ダブラー部材に高価なオーステナイト鋼板を使用する場合には、材料費が高騰するという問題がある。 However, the technique described in Patent Document 6 requires strict construction control during welding in order to limit the weld leg length and weld width, and there are problems such as a decrease in productivity of welding construction and an increase in construction costs. . In addition, in a structure requiring partial penetration welding with a small unwelded portion, there is a problem that sufficient brittle crack arrestability cannot be ensured. In addition, the technique described in Patent Document 7 has a problem that the construction cost increases due to processing and welding of the doubler member, and a problem that the material cost rises when an expensive austenitic steel plate is used for the doubler member. .
　本発明は、上記したような従来技術の問題を解決し、溶接時の厳格な施工管理を必要とすることなく、板厚：50mm以上の被接合部材（フランジ）に発生した脆性亀裂の接合部材（ウェブ）への伝播を、大規模破壊に至る前に、阻止することができる、脆性亀裂伝播停止性能に優れた溶接構造体を提供することを目的とする。なお、本発明が対象とする溶接構造体は、接合部材の端面を被接合部材の表面に突き合せ、これらを隅肉溶接または部分溶込み溶接により溶接接合してなるT継手を有する溶接構造体である。 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. In addition, 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.
　本発明者らは、上記した目的を達成するために、T継手の脆性亀裂伝播停止靭性に及ぼす各種要因について鋭意検討した。その結果、T継手の溶接金属組織を主としてオーステナイト相からなる組織とすれば、溶接金属を高靭性とすることができ、たとえ、溶接金属の溶接脚長や溶着幅が16mm以上となる場合や、接合に部分溶込み溶接を適用する場合であっても、脆性亀裂伝播停止性能に優れたT継手とすることができることに思い至った。そして、これにより、接合部材（ウェブ）に使用する厚鋼板の脆性亀裂伝播停止性能を特別に考慮することもなく、被接合部材（フランジ）で発生した脆性亀裂の接合部材（ウェブ）への伝播を、T継手の溶接金属で阻止することができることを知見した。 In order to achieve the above objectives, the present inventors diligently studied various factors affecting the brittle crack arrest toughness of T-joints. As a result, if the weld metal structure of the T-joint is made mainly of an austenite phase, the weld metal can be made to have high toughness. I came to realize that even if partial penetration welding is applied to the joint, it is possible to obtain a T-joint with excellent brittle crack arrestability. 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.
　本発明は、上記した知見に、さらに検討を加えて完成されたものである。すなわち、本発明の要旨は次のとおりである。
［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、前記接合部材と前記被接合部材とを接合するT継手を備える、溶接構造体であって、
　前記T継手の溶接脚長および溶着幅のうちの長い方の値であるLが16mm以上であり、
　前記T継手の溶接金属が、
　　質量％で、C：0.10～0.70％、Si：0.10～1.00％、Mn：15.00～28.00％、P：0.030％以下、S：0.015％以下、Ni：1.00～5.00％、Cr：0.50～4.00％、Mo：2.00％以下、N：0.150％以下およびO：0.050％以下であり、残部がFe及び不可避的不純物である、溶接金属組成と、
　　オーステナイト相が面積％で80％以上である、溶接金属組織と、を有する、溶接構造体。
［２］前記溶接金属組成が、さらに、質量％で、
（ａ）V：0.10％以下、Ti：0.10％以下およびNb：0.10％以下のうちから選んだ１種または２種以上、
　ならびに
（ｂ）Cu：1.00％以下、Al：0.10％以下、Ca：0.010％以下およびREM：0.020％以下のうちから選んだ１種または２種以上
のうちの少なくとも一方を含有する、［１］に記載の溶接構造体。
［３］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未溶着部が存在し、かつ、前記接合部材の板厚に対する前記未溶着部の幅の比率である未溶着比率Yが30％以上である、［１］に記載の溶接構造体。
［４］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未溶着部が存在し、かつ、前記接合部材の板厚に対する前記未溶着部の幅の比率である未溶着比率Yが30％以上である、［２］に記載の溶接構造体。
［５］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、［１］に記載の溶接構造体。
［６］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、［２］に記載の溶接構造体。
［７］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、［３］に記載の溶接構造体。
［８］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、［４］に記載の溶接構造体。
［９］前記接合部材が、突合せ溶接継手部を有し、該接合部材の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、前記接合部材を、配設してなる、［５］に記載の溶接構造体。
［１０］前記接合部材が、突合せ溶接継手部を有し、該接合部材の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、前記接合部材を、配設してなる、［６］に記載の溶接構造体。
［１１］前記接合部材が、突合せ溶接継手部を有し、該接合部材の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、前記接合部材を、配設してなる、［７］に記載の溶接構造体。
［１２］前記接合部材が、突合せ溶接継手部を有し、該接合部材の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、前記接合部材を、配設してなる、［８］に記載の溶接構造体。
［１３］前記接合部材の板厚が50mm以上である、請求項［１］ないし［１２］のいずれかに記載の溶接構造体。
［１４］前記接合部材と前記被接合部材との間の隙間が10mm以下である、請求項［１］ないし［１２］のいずれかに記載の溶接構造体。
［１５］前記接合部材と前記被接合部材との間の隙間が10mm以下である、［１３］に記載の溶接構造体。 The present invention has been completed by further studies on the above findings. That is, the gist of the present invention is as follows.
[1] A welded structure comprising a T joint for joining the joint member and the joint member, wherein the end face of the joint member is butted against the surface of the joint member having a plate thickness of 50 mm or more,
L, which is the longer value of the weld leg length and weld width of the T joint, is 16 mm or more,
The weld metal of the T joint is
% by mass, C: 0.10-0.70%, Si: 0.10-1.00%, Mn: 15.00-28.00%, P: 0.030% or less, S: 0.015% or less, Ni: 1.00-5.00%, Cr: 0.50-4.00% , Mo: 2.00% or less, N: 0.150% or less and O: 0.050% or less, the balance being Fe and unavoidable impurities;
A welded structure having a weld metallographic structure in which the austenitic phase is 80% or more by area.
[2] The composition of the weld metal further contains, in mass %,
(a) one or more selected from V: 0.10% or less, Ti: 0.10% or less, and Nb: 0.10% or less;
and (b) at least one selected from Cu: 1.00% or less, Al: 0.10% or less, Ca: 0.010% or less, and REM: 0.020% or less, [1] Welded structure according to.
[3] In the T-joint, there is an unwelded portion on the surface where the end surface of the joining member and the surface of the member to be joined meet, and the ratio of the width of the unwelded portion to the plate thickness of the joining member The welded structure according to [1], wherein the unwelded ratio Y is 30% or more.
[4] In the T-joint, there is an unwelded portion on the surface where the end surface of the joining member and the surface of the member to be joined are butted against each other, and the ratio of the width of the unwelded portion to the plate thickness of the joining member The welded structure according to [2], wherein the unwelded ratio Y is 30% or more.
[5] The welded structure according to [1], wherein the member to be joined has a butt weld joint so as to intersect the member to be joined.
[6] The welded structure according to [2], wherein the member to be joined has a butt weld joint so as to intersect the member to be joined.
[7] The welded structure according to [3], wherein the member to be joined has a butt weld joint that intersects the member to be joined.
[8] The welded structure according to [4], wherein the member to be joined has a butt weld joint so as to intersect the member to be joined.
[9] The joining member has a butt-welded joint portion, and the joining member is arranged so that the butt-welded joint portion of the joining member and the butt-welded joint portion of the member to be welded intersect. The welded structure according to [5].
[10] The joining member has a butt-welded joint portion, and the joining member is arranged so that the butt-welded joint portion of the joining member and the butt-welded joint portion of the member to be welded intersect. The welded structure according to [6].
[11] The joining member has a butt-welded joint portion, and the joining member is arranged so that the butt-welded joint portion of the joining member and the butt-welded joint portion of the member to be welded intersect. The welded structure according to [7].
[12] The joining member has a butt-welded joint, and the joining member is arranged so that the butt-welded joint of the joining member and the butt-welded joint of the member to be welded intersect. The welded structure according to [8].
[13] The welded structure according to any one of [1] to [12], wherein the joining member has a plate thickness of 50 mm or more.
[14] The welded structure according to any one of [1] to [12], wherein the gap between the joining member and the member to be joined is 10 mm or less.
[15] The welded structure according to [13], wherein the gap between the member to be joined and the member to be joined is 10 mm or less.
　本発明によれば、板厚50mm以上の、厚肉の被接合部材から発生した脆性亀裂の接合部材への伝播を、大規模破壊に到る前に阻止することが可能となる。本発明によれば、特に大型のコンテナ船やバルクキャリアーなどの船体分離など、大規模な脆性破壊を回避でき、船体構造の安全性を向上させるうえで大きな効果をもたらし、産業上格段の効果を奏する。また、本発明によれば、特殊な鋼材を使用することなく、また安全性を損なうこともなく、溶接施工時に溶接材料の選定や溶接条件の調整を行うことだけで、脆性亀裂伝播停止性能に優れた溶接構造体を製造できるという効果もある。 According to the present invention, it is possible to prevent the propagation of brittle cracks generated from thick-walled members to be joined with a plate thickness of 50 mm or more to the members to be joined before large-scale failure occurs. According to the present invention, it is possible to avoid large-scale brittle fractures such as separation of hulls of large container ships and bulk carriers in particular, and it is highly effective in improving the safety of hull structures, and has a remarkable industrial effect. Play. In addition, according to the present invention, 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.
T継手の継手断面の一例を模式的に示す説明図である。FIG. 4 is an explanatory diagram schematically showing an example of a joint cross section of a T joint; T継手の他の一例を模式的に示す説明図である。（ａ）は外観図、（ｂ）は断面図である。FIG. 4 is an explanatory diagram schematically showing another example of a T-joint; (a) is an external view, and (b) is a sectional view. T継手の他の一例を模式的に示す説明図である。（ａ）は外観図、（ｂ）は断面図である。FIG. 4 is an explanatory diagram schematically showing another example of a T-joint; (a) is an external view, and (b) is a sectional view. 超大型構造モデル試験体の形状を模式的に示す説明図である。FIG. 4 is an explanatory diagram schematically showing the shape of a super-large structural model specimen; T継手の開先形状の一例を示す説明図である。FIG. 4 is an explanatory diagram showing an example of a groove shape of a T-joint;
　本発明の一実施形態に従う溶接構造体は、接合部材１の端面を被接合部材２の表面に突き合せて、接合部材１と被溶接部材２とを接合するT継手を備える溶接構造体である。本発明の一実施形態に従う溶接構造体は、例えば、船舶の船体外板を被接合部材とし、隔壁を接合部材とする船体構造、あるいはデッキを被接合部材とし、ハッチを接合部材とする船体構造に適用可能である。なお、上記のT継手は、接合部材１と、被接合部材２と、溶接金属５と、を有する。 A welded structure according to one embodiment of the present invention is a welded structure provided with a T-joint that joins the joining member 1 and the to-be-welded member 2 by abutting the end face of the joining member 1 against the surface of the to-be-joined member 2. . A welded structure according to an embodiment of the present invention is, for example, a hull structure in which a hull skin of a ship is a member to be joined and a bulkhead is a member to be joined, or a hull structure in which a deck is a member to be joined and a hatch is a member to be joined. applicable to In addition, the T-joint described above has a joining member 1 , a member to be joined 2 , and a weld metal 5 .
　なお、使用する被接合部材２は、板厚50mm以上、好ましくは60mm以上120mm以下の厚鋼板を素材とする。また、接合部材１は、好ましくは板厚50mm以上、より好ましくは60mm以上120mm以下の厚鋼板を素材とすることが好ましい。なお、接合部材１および被接合部材２に用いる厚鋼板の鋼種は特に限定されず、例えば、降伏強さ：350～490Ｎ/mm2（MPa）の厚鋼板を好適に用いることができる。 The member to be joined 2 to be used is 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. Also, the joining member 1 is preferably made of a thick steel plate having a thickness of 50 mm or more, more preferably 60 mm or more and 120 mm or less. The steel type of the thick steel plate used for the joining member 1 and the joined member 2 is not particularly limited, and for example, a thick steel plate having a yield strength of 350 to 490 N/mm 2 (MPa) can be suitably used.
　なお、本発明の一実施形態に従う溶接構造体で備えるT継手は、溶接金属５を有し、溶接脚長３および溶着幅１３のうちの長い方の値であるLを16mm以上とする。また、本発明の一実施形態に従う溶接構造体では、接合部材１と被接合部材２との突き合わせ面に、構造不連続部となる未溶着部４（未溶着部の幅１６）を存在させてもよい。また、未溶着部４を存在させる場合、接合部材１の板厚に対する未溶着部の幅１６の比率である未溶着比率Y（＝B/tw×100、B：未溶着部の幅（mm）、tw：接合部材の板厚（mm））を30％以上とすることが好ましい。未溶着部４を存在させることにより、被接合部材２を伝播してきた脆性亀裂は、突合せ面において停止しやすくなる。未溶着比率Yの上限は特に限定されないが、所定の強度を確保する観点などから、未溶着比率Yは98％以下が好ましい。なお、溶接脚長３、溶着幅１３および未溶着部の幅１６は、T継手の継手断面（後述する図１に示す継手断面であり、当該継手断面は、接合部材１の板厚方向をｘ軸、被接合部材２の板厚方向をｙ軸としたときのｘｙ平面に平行な面である。）において測定する。 The T-joint provided in the welded structure according to one embodiment of the present invention has weld metal 5, and L, which is the longer one of weld leg length 3 and weld width 13, is set to 16 mm or more. In addition, in the welded structure according to one embodiment of the present invention, the non-welded portion 4 (the width 16 of the unwelded portion), which is a structural discontinuity, is present on the butting surfaces of the joining member 1 and the member to be joined 2. good too. When the unwelded portion 4 exists, the unwelded ratio Y (= B/tw × 100, B: width of the unwelded portion (mm) , tw: plate thickness (mm) of the joining member) is preferably 30% or more. The presence of the unwelded portion 4 makes it easier for the brittle crack that has propagated through the members to be joined 2 to stop at the butt surfaces. Although the upper limit of the unwelded ratio Y is not particularly limited, the unwelded ratio Y is preferably 98% or less from the viewpoint of ensuring a predetermined strength. The welded leg length 3, the welded width 13, and the width 16 of the unwelded portion are the joint cross section of the T joint (the joint cross section shown in FIG. 1, which will be described later). , which is a plane parallel to the xy plane when the plate thickness direction of the member 2 to be joined is taken as the y axis.
　この状態を継手断面で図１に示す。図１（ａ）は、接合部材１を被接合部材２に対して直立して接合した場合を示すが、これに限定されない。例えば、図１（ｂ）に示すように、接合部材１を被接合部材２に対して角度θだけ傾けて接合してもよい。また、図１（ｃ）に示すように、接合部材１と被接合部材２の間に隙間１４を設け、さらに図１（ｄ）に示すように、隙間１４にスペーサー１５を挿入してもよい。また、隙間１４は溶接時の工数削減の観点から、10mm以下とすることが好ましい。 This state is shown in Fig. 1 as a cross section of the joint. Although FIG. 1(a) shows a case where the member to be joined 1 is joined upright to the member to be joined 2, the present invention is not limited to this. For example, as shown in FIG. 1(b), the joining member 1 may be joined at an angle θ with respect to the member 2 to be joined. Alternatively, as shown in FIG. 1(c), a gap 14 may be provided between the member to be joined 1 and the member to be joined 2, and a spacer 15 may be inserted into the gap 14 as shown in FIG. 1(d). . In addition, the gap 14 is preferably 10 mm or less from the viewpoint of reducing man-hours during welding.
　脆性亀裂は、欠陥の少ない鋼板母材部で発生することは極めて稀で、多くは溶接部で発生している。図２や図３に示すようなT継手では、脆性亀裂は、突合せ溶接継手部１１から発生する。発生した脆性亀裂が接合部材１へ伝播することを阻止するためには、構造の不連続部を存在させることが好ましい。構造の不連続部として、例えば、上述したように、T継手の被接合部材２と接合部材１との突合せ面に未溶着部４を存在させることが好ましい。本発明の一実施形態に従う溶接構造体では、T継手の溶接金属を靭性に優れるものとするため、構造の不連続部を存在させることは、必ずしも必要ではない。ただし、構造の不連続部を存在させることにより、脆性亀裂の伝播阻止がより容易になる。 It is extremely rare for brittle cracks to occur in base metal parts of steel plates with few defects, and most occur in welded parts. In a T-joint as shown in FIGS. 2 and 3, brittle cracks are generated from the butt-welded joint portion 11 . In order to prevent the generated brittle crack from propagating to the joint member 1, it is preferable to have a structural discontinuity. As a discontinuous portion of the structure, for example, as described above, it is preferable to have an unwelded portion 4 on the butting surfaces of the joined member 2 and the joining member 1 of the T-joint. In the welded structure according to one embodiment of the present invention, it is not always necessary to have structural discontinuities in order to make the weld metal of the T-joint excellent in toughness. However, the presence of structural discontinuities makes it easier to stop propagation of brittle cracks.
　図２に示す溶接構造体は、被接合部材２を突合せ溶接継手１１で接合された鋼板とし、接合部材１をその突合せ溶接継手の溶接部１１と交差するように、溶接した溶接構造体である。また、図３に示す溶接構造体は、接合部材１を突合せ溶接継手１２で接合された鋼板とし、被接合部材２を突合せ溶接継手１１で接合された鋼板とし、接合部材１の突合せ溶接継手１２と被接合部材２の突合せ溶接継手１１とが交差するように溶接した溶接構造体である。 The welded structure shown in FIG. 2 is a welded structure in which the member to be joined 2 is a steel plate joined by a butt weld joint 11, and the joint member 1 is welded so as to intersect the welded portion 11 of the butt weld joint. . In the welded structure shown in FIG. 3, the joint member 1 is a steel plate joined by a butt weld joint 12, the member to be joined 2 is a steel plate joined by a butt weld joint 11, and the butt weld joint 12 of the joint member 1 is used. and the butt welded joint 11 of the member to be joined 2 are welded so as to intersect each other.
　図２および図３では、接合部材１と突合せ溶接継手１１とを直交するように、配置しているが、これに限定されない。斜めに交差させても良いことは言うまでもない。また、溶接継手の製造方法は、特に限定する必要はなく、常用の製造方法がいずれも適用できる。例えば、被接合部材用鋼板同士、接合部材用鋼板同士を突合せ溶接し、突合せ溶接継手を有する接合部材および被接合部材を得る。そして、得られた接合部材および被接合部材を溶接し、T継手を製造してもよい。また、突合せ溶接前の、一組の接合部材用鋼板を被接合部材に仮付溶接し、ついで接合部材用鋼板同士を突合せ溶接し、突合せ溶接継手を有する接合部材を得る。そして、得られた接合部材を被接合部材に本溶接し、T継手を製造してもよい。 In FIGS. 2 and 3, the joint member 1 and the butt-welded joint 11 are arranged so as to be perpendicular to each other, but the present invention is not limited to this. Needless to say, they may cross each other obliquely. Also, the method for manufacturing the welded joint is not particularly limited, and any commonly used manufacturing method can be applied. For example, steel plates for members to be joined and steel plates for members to be joined are butt-welded to obtain joining members and members to be joined having butt-welded joints. Then, the obtained joining member and the member to be joined may be welded to produce a T-joint. A set of steel plates for joining members before butt welding is tack-welded to a member to be joined, and then the steel plates for joining members are butt-welded to each other to obtain a joining member having a butt-welded joint. Then, the obtained joining member may be permanently welded to the member to be joined to manufacture a T-joint.
　本発明の一実施形態に従う溶接構造体では、T継手の溶接脚長３および溶着幅１３のうちの長い方の値であるLは、16mm以上とする。Lが16mm未満、つまり、溶接脚長３および溶着幅１３がともに16mm未満である場合、脆性亀裂伝播停止性能を確保するには有利である。しかしながら、部材板厚が80mmを超えるような場合に、溶接部の強度確保が困難となる。また、部材板厚が80mm以下であっても、施工時の手直し等により、溶接部の強度確保が難しくなる危険性が高くなる。なお、Lの上限は特に限定されないが、施工能率等の観点から、Lは30mm以下とすることが好ましい。 In the welded structure according to one embodiment of the present invention, L, which is the longer value of the weld leg length 3 and the weld width 13 of the T-joint, shall be 16 mm or more. If L is less than 16 mm, that is, both the weld leg length 3 and the weld width 13 are less than 16 mm, it is advantageous to ensure brittle crack arrestability. However, when the member plate thickness exceeds 80 mm, it becomes difficult to ensure the strength of the welded portion. In addition, even if the plate thickness of the member is 80 mm or less, 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 limit of L is not particularly limited, L is preferably 30 mm or less from the viewpoint of construction efficiency and the like.
　また、本発明の一実施形態に従う溶接構造体では、T継手の溶接金属の組織（以下、溶接金属組織ともいう）を、オーステナイト相が面積％（面積率）で80％以上である組織とする。オーステナイト相の上限は特に限定されず、面積％で100％であってもよい。オーステナイト相以外の相（以下、残部相ともいう）は面積％で0～20％であり、残部相としては、例えば、フェライト相等を例示できる。 Further, in the welded structure according to one embodiment of the present invention, the structure of the weld metal of the T-joint (hereinafter also referred to as the weld metal structure) is a structure in which the austenite phase is 80% or more in terms of area% (area ratio). . The upper limit of the austenite phase is not particularly limited, and may be 100% in terms of area %. A phase other than the austenite phase (hereinafter also referred to as the residual phase) is 0 to 20% in terms of area %, and examples of the residual phase include ferrite phase and the like.
　溶接金属組織を、オーステナイト相が面積％で80％以上である組織とすることにより、溶接金属の靭性が向上する。これにより、Lが16mm以上の場合においても、被接合部材で発生した脆性亀裂の伝播をT継手の溶接金属で停止し、接合部材への脆性亀裂の伝播を阻止できる。なお、上記した組織を有する溶接金属は、溶接構造体の強度確保の観点から、ビッカース硬さで170～260HV（降伏強さで390MPa以上、引張強さで490MPa以上）の硬さ（強度）特性を有することが好ましい。 By setting the weld metal structure to a structure in which the austenite phase is 80% or more in area%, the toughness of the weld metal is improved. As a result, even when L is 16 mm or more, the propagation of brittle cracks generated in the members to be joined can be stopped by the weld metal of the T-joint, and the propagation of brittle cracks to the members to be joined can be prevented. In addition, from the viewpoint of ensuring the strength of the welded structure, 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
　また、T継手の溶接金属は、質量％で、C：0.10～0.70％、Si：0.10～1.00％、Mn：15.00～28.00％、P：0.030％以下、S：0.015％以下、Ni：1.00～5.00％、Cr：0.50～4.00％、Mo：2.00％以下、N：0.150％以下およびO：0.050％以下であり、残部がFe及び不可避的不純物からなる、溶接金属組成を有する。 In addition, the mass % of the weld metal of the T joint is C: 0.10 to 0.70%, Si: 0.10 to 1.00%, Mn: 15.00 to 28.00%, P: 0.030% or less, S: 0.015% or less, Ni: 1.00% or more. 5.00% Cr: 0.50 to 4.00% Mo: 2.00% or less N: 0.150% or less O: 0.050% or less The balance consists of Fe and unavoidable impurities.
　上述したように、溶接金属組織を、上記したオーステナイト相が面積％で80％以上である組織とすることにより、溶接金属の靭性が向上する。これにより、Lが16mm以上の場合においても、被接合部材で発生した脆性亀裂の伝播をT継手の溶接金属で停止し、接合部材への脆性亀裂の伝播を阻止できる。 As described above, the toughness of the weld metal is improved by setting the weld metal structure to a structure in which the austenite phase is 80% or more in terms of area %. As a result, even when L is 16 mm or more, the propagation of brittle cracks generated in the members to be joined can be stopped by the weld metal of the T-joint, and the propagation of brittle cracks to the members to be joined can be prevented.
　つぎに、上記の溶接金属組成の限定理由について説明する。以下、溶接金属組成における質量％は、単に％で記す。 Next, the reasons for limiting the composition of the weld metal will be explained. Hereinafter, mass % in the weld metal composition is simply expressed as %.
　C：0.10～0.70％
　Cは、オーステナイトを安定化させる元素である。また、Cは、固溶強化により、溶接金属の強度を上昇させる作用を有する元素である。このような効果を得るためには、Cの0.10％以上の含有を必要とする。しかし、C含有量が0.70％を超えると、溶接時の高温割れが生じやすくなる。そのため、C含有量は0.10～0.70％とする。なお、C含有量は、好ましくは0.20～0.60％である。 C: 0.10-0.70%
C is an element that stabilizes austenite. Also, C is an element that has the effect of increasing the strength of the weld metal through solid-solution strengthening. In order to obtain such effects, the C content must be 0.10% or more. However, when the C content exceeds 0.70%, hot cracks tend to occur during welding. Therefore, the C content should be 0.10-0.70%. The C content is preferably 0.20-0.60%.
　Si：0.10～1.00％
　Siは、炭化物の析出を抑制することで、Cをオーステナイトに固溶させ、オーステナイトを安定化させる。そのような効果を得るためには、Siの0.10％以上の含有を必要とする。しかし、Si含有量が1.00％を超えると、Siが、凝固時に偏析して、凝固セル界面に液相を生成する。これにより、耐高温割れ性を低下させる。さらには靭性が低下する。そのため、Si含有量は0.10～1.00％とする。なお、Si含有量は、好ましくは0.20～0.90％である。 Si: 0.10-1.00%
Si suppresses the precipitation of carbides, causes C to dissolve in austenite, and stabilizes austenite. In order to obtain such an effect, the content of Si must be 0.10% or more. However, when the Si content exceeds 1.00%, Si segregates during solidification to form a liquid phase at solidification cell interfaces. This reduces hot cracking resistance. Furthermore, the toughness is lowered. Therefore, the Si content should be 0.10 to 1.00%. Incidentally, the Si content is preferably 0.20 to 0.90%.
　Mn：15.00～28.00％
　Mnは、安価に、オーステナイト相を安定化する元素である。そのためには、Mnの15.00％以上の含有を必要とする。Mn含有量が15.00％未満では、オーステナイトの安定度が不足する。これにより、溶接金属中に硬質のマルテンサイト相が生成し、靭性が低下する。一方、Mn含有量が28.00％を超えると、凝固時に過度のMn偏析が発生し、高温割れを誘発する。そのため、Mn含有量は15.00～28.00％とする。なお、Mn含有量は、好ましくは17.00～26.00％である。 Mn: 15.00-28.00%
Mn is an element that stabilizes the austenite phase at low cost. For that purpose, the content of Mn is required to be 15.00% or more. If the Mn content is less than 15.00%, the stability of austenite is insufficient. As a result, a hard martensite phase is generated in the weld metal and the toughness is lowered. On the other hand, if the Mn content exceeds 28.00%, excessive Mn segregation occurs during solidification, which induces hot cracking. Therefore, the Mn content should be 15.00-28.00%. The Mn content is preferably 17.00-26.00%.
　P：0.030％以下
　Pは、結晶粒界に偏析し、高温割れを誘発する元素である。そのため、Pはできるだけ低減することが好ましいが、0.030％以下であれば許容できる。そのため、P含有量は0.030％以下とする。なお、Pの過度の低減は、精練コストの高騰を招く。そのため、P含有量は0.002％以上に調整することが好ましい。 P: 0.030% or less P is an element that segregates at grain boundaries and induces hot cracking. Therefore, it is preferable to reduce P as much as possible, but 0.030% or less is permissible. Therefore, the P content should be 0.030% or less. Excessive reduction of P invites an increase in refining cost. Therefore, it is preferable to adjust the P content to 0.002% or more.
　S：0.015％以下
　Sは、結晶粒界に偏析し、高温割れを誘発する元素である。そのため、Sはできるだけ低減することが好ましいが、0.015％以下であれば許容できる。そのため、S含有量は0.015％以下とする。なお、Sの過度の低減は、精練コストの高騰を招く。そのため、S含有量は0.001％以上に調整することが好ましい。 S: 0.015% or less S is an element that segregates at grain boundaries and induces hot cracking. Therefore, it is preferable to reduce S as much as possible, but 0.015% or less is permissible. Therefore, the S content should be 0.015% or less. Note that an excessive reduction in S causes an increase in refining costs. Therefore, it is preferable to adjust the S content to 0.001% or more.
　Ni：1.00～5.00％
　Niは、オーステナイト粒界を強化する元素であり、粒界の脆化を抑制することで、高温割れの発生を抑制する。このような効果を得るためには、Niの1.00％以上の含有を必要とする。また、Niは、オーステナイト相を安定化させる効果もある。しかし、Niは高価な元素であり、5.00％を超える含有は、経済的に不利となる。そのため、Ni含有量は1.00～5.00％とする。 Ni: 1.00-5.00%
Ni is an element that strengthens austenite grain boundaries, and by suppressing embrittlement of grain boundaries, suppresses the occurrence of hot cracks. In order to obtain such effects, the content of Ni must be 1.00% or more. Ni also has the effect of stabilizing the austenite phase. However, Ni is an expensive element, and a Ni content exceeding 5.00% is economically disadvantageous. Therefore, the Ni content should be 1.00 to 5.00%.
　Cr：0.50～4.00％
　Crは、溶接金属の強度を向上させる効果がある。Cr含有量が0.50％未満では、上記した効果を確保できない。一方、Cr含有量が4.00％を超えると、溶接金属の靱性および耐高温割れ性が低下する。そのため、Cr含有量は0.50～4.00％とする。なお、Cr含有量は、好ましくは0.70～3.00％である。 Cr: 0.50-4.00%
Cr has the effect of improving the strength of the weld metal. If the Cr content is less than 0.50%, the above effects cannot be secured. On the other hand, when the Cr content exceeds 4.00%, the toughness and hot cracking resistance of the weld metal deteriorate. Therefore, the Cr content should be 0.50 to 4.00%. The Cr content is preferably 0.70-3.00%.
　Mo：2.00％以下
　Moは、オーステナイト粒界を強化する元素であり、粒界の脆化を抑制することで、高温割れの発生を抑制する。また、Moは、溶接金属を硬化させることにより、耐摩耗性を向上させる作用も有する。このような効果を得るためには、Mo含有量を0.10％以上とすることが好ましい。一方、Mo含有量が2.00％を超えると、粒内が硬化しすぎて、相対的に粒界が弱くなり、高温割れが発生する。そのため、Mo含有量は2.00％以下とする。なお、Mo含有量は、より好ましくは0.20～1.90％である。 Mo: 2.00% or less Mo is an element that strengthens austenite grain boundaries, and by suppressing embrittlement of grain boundaries, suppresses the occurrence of hot cracks. Mo also has the effect of improving wear resistance by hardening the weld metal. In order to obtain such effects, the Mo content is preferably 0.10% or more. On the other hand, if the Mo content exceeds 2.00%, the grain interiors are too hardened, the grain boundaries become relatively weak, and hot cracking occurs. Therefore, the Mo content should be 2.00% or less. Incidentally, the Mo content is more preferably 0.20 to 1.90%.
　N：0.150％以下
　Nは、不可避的に混入する元素である。ただし、Nは、Cと同様に、溶接金属の強度向上に有効に寄与する。また、Nは、オーステナイト相を安定化し、極低温靱性を安定的に向上させる元素でもある。このような効果は、Nの0.003％以上の含有で顕著となるため、N含有量は0.003％以上が好ましい。しかし、N含有量が0.150％を超えると、窒化物を形成し、低温靱性が低下する。そのため、N含有量は0.150％以下とする。なお、N含有量は、好ましくは0.003～0.120％である。 N: 0.150% or less N is an element that is unavoidably mixed. However, N, like C, effectively contributes to improving the strength of the weld metal. N is also an element that stabilizes the austenite phase and stably improves the cryogenic toughness. Since such an effect becomes remarkable when the N content is 0.003% or more, the N content is preferably 0.003% or more. However, when the N content exceeds 0.150%, nitrides are formed and the low temperature toughness is lowered. Therefore, the N content should be 0.150% or less. The N content is preferably 0.003-0.120%.
　O：0.050％以下
　O（酸素）は、不可避的に混入する元素である。ただし、Oは、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、Oの0.003％以上の含有で著しくなるため、O含有量は0.003％以上が好ましい。しかしながら、O含有量が0.050％を超えると、酸化物の粗大化が著しくなる。そのため、O（酸素）含有量は0.050％以下とする。なお、O含有量は、好ましくは0.003～0.040％である。 O: 0.050% or less O (oxygen) is an unavoidable element. However, O forms Al-based oxides and Si-based oxides in the weld metal and contributes to suppression of coarsening of the solidified structure. Since such an effect becomes significant when the O content is 0.003% or more, the O content is preferably 0.003% or more. However, when the O content exceeds 0.050%, coarsening of the oxide becomes significant. Therefore, the O (oxygen) content should be 0.050% or less. The O content is preferably 0.003-0.040%.
　上記した成分が、溶接金属組成の基本成分であるが、上記した基本成分に加えてさらに、選択成分として、任意に、
（ａ）V：0.10％以下、Ti：0.10％以下およびNb：0.10％以下のうちから選んだ１種または２種以上、
　ならびに
（ｂ）Cu：1.00％以下、Al：0.10％以下、Ca：0.010％以下およびREM：0.020％以下のうちから選んだ１種または２種以上
のうちの少なくとも一方を含有させることができる。 The components described above are the basic components of the weld metal composition, but in addition to the basic components described above, optional components include:
(a) one or more selected from V: 0.10% or less, Ti: 0.10% or less, and Nb: 0.10% or less;
and (b) at least one selected from Cu: 1.00% or less, Al: 0.10% or less, Ca: 0.010% or less, and REM: 0.020% or less.
（ａ）V：0.10％以下、Ti：0.10％以下およびNb：0.10％以下のうちから選んだ１種または２種以上
　V、TiおよびNbはいずれも、炭化物形成元素で、粒内に微細な炭化物を析出させて溶接金属の強度増加に寄与する元素であり、任意に１種または２種以上を含有させることができる。 (a) One or more selected from V: 0.10% or less, Ti: 0.10% or less, and Nb: 0.10% or less It is an element that precipitates carbides and contributes to an increase in the strength of the weld metal, and one or more of these elements can be optionally contained.
　V：0.10％以下
　Vは、炭化物形成元素で、粒内に微細な炭化物を析出させて、溶接金属の強度向上に寄与する。このような効果を得るためには、Vを0.001％以上含有させることが好ましい。しかし、V含有量が0.10％を超えると、過剰な炭化物が破壊の発生起点となるため、低温靭性が低下する。そのため、Vを含有させる場合、V含有量は0.10％以下が好ましい。なお、V含有量は、より好ましくは0.002～0.050％である。 V: 0.10% or less V is a carbide-forming element that precipitates fine carbides in grains and contributes to improving the strength of the weld metal. In order to obtain such effects, it is preferable to contain 0.001% or more of V. However, if the V content exceeds 0.10%, the excessive carbides act as starting points for fracture, resulting in a decrease in low-temperature toughness. Therefore, when V is contained, the V content is preferably 0.10% or less. The V content is more preferably 0.002-0.050%.
　Ti：0.10％以下
　また、TiもVと同様に、炭化物形成元素で、微細な炭化物を析出させて、溶接金属の強度向上に寄与する。このような効果を得るためには、Tiを0.001％以上含有させることが好ましい。しかし、Ti含有量が0.10％を超えると、過剰な炭化物が破壊の発生起点となるため、低温靭性が低下する。そのため、Tiを含有させる場合、Ti含有量は0.10％以下が好ましい。なお、Ti含有量は、より好ましくは0.002～0.050％である。 Ti: 0.10% or less Ti, like V, is a carbide-forming element, which precipitates fine carbides and contributes to improving the strength of the weld metal. In order to obtain such effects, it is preferable to contain 0.001% or more of Ti. However, when the Ti content exceeds 0.10%, the excessive carbides act as starting points for fractures, resulting in a decrease in low-temperature toughness. Therefore, when Ti is contained, the Ti content is preferably 0.10% or less. Incidentally, the Ti content is more preferably 0.002 to 0.050%.
　Nb：0.10％以下
　また、NbもVおよびTiと同様に、炭化物形成元素で、微細な炭化物を析出させて、溶接金属の強度向上に寄与する。このような効果を得るためには、Nbを0.001％以上含有させることが好ましい。しかし、Nb含有量が0.10％を超えると、過剰な炭化物が破壊の発生起点となるため、低温靭性が低下する。そのため、Nbを含有させる場合、Nb含有量は0.10％以下が好ましい。なお、Nb含有量は、より好ましくは0.002～0.090％である。 Nb: 0.10% or less Like V and Ti, Nb is also a carbide-forming element that precipitates fine carbides and contributes to improving the strength of the weld metal. In order to obtain such effects, it is preferable to contain 0.001% or more of Nb. However, if the Nb content exceeds 0.10%, excessive carbides act as starting points for fractures, resulting in a decrease in low-temperature toughness. Therefore, when Nb is contained, the Nb content is preferably 0.10% or less. The Nb content is more preferably 0.002-0.090%.
（ｂ）Cu：1.00％以下、Al：0.10％以下、Ca：0.010％以下およびREM：0.020％以下のうちから選んだ１種または２種以上
　Cuは、オーステナイト安定化に寄与する元素である。Alは、脱酸剤として作用する元素である。また、CaおよびREMは高温割れの抑制に寄与する元素である。Cu、Al、CaおよびREMは、任意に１種または２種以上を含有できる。 (b) One or more selected from Cu: 1.00% or less, Al: 0.10% or less, Ca: 0.010% or less, and REM: 0.020% or less Cu is an element that contributes to austenite stabilization. Al is an element that acts as a deoxidizing agent. Also, Ca and REM are elements that contribute to the suppression of hot cracking. Cu, Al, Ca and REM can optionally contain one or more.
　Cu：1.00％以下
　Cuは、オーステナイト相を安定化する元素である。このような効果を得るためには、Cuを0.01％以上含有させることが好ましい。しかし、Cu含有量が1.00％を超えると、粒界で低融点の液相が生成するため、高温割れが発生する。そのため、Cuを含有させる場合、Cu含有量は1.00％以下が好ましい。なお、Cu含有量は、より好ましくは0.02～0.80％である。 Cu: 1.00% or less Cu is an element that stabilizes the austenite phase. In order to obtain such effects, it is preferable to contain 0.01% or more of Cu. However, when the Cu content exceeds 1.00%, a liquid phase with a low melting point is generated at the grain boundary, resulting in hot cracking. Therefore, when Cu is contained, the Cu content is preferably 1.00% or less. The Cu content is more preferably 0.02-0.80%.
　Al：0.10％以下
　Alは、脱酸剤として作用する。また、Alは、溶融金属の粘性を高め、ビード形状を安定的に保持し、スパッタの発生を低減する重要な作用を有する。さらに、Alは、固液共存温度範囲を小さくして、溶接金属の高温割れ発生の抑制に寄与する。このような効果は、Alの0.001％以上の含有で顕著となるため、Al含有量は0.001％以上が好ましい。しかし、Al含有量が0.10％を超えると、溶融金属の粘性が高くなりすぎて、逆に、スパッタの増加や、ビードが広がらずに融合不良などの欠陥が増加する。そのため、Alを含有させる場合、Al含有量は0.10％以下が好ましい。なお、Al含有量は、より好ましくは0.002～0.090％である。 Al: 0.10% or less Al acts as a deoxidizing agent. Also, Al has an important effect of increasing the viscosity of the molten metal, stably maintaining the bead shape, and reducing the occurrence of spatter. Furthermore, Al reduces the solid-liquid coexistence temperature range and contributes to suppressing the occurrence of hot cracks in the weld metal. Since such an effect becomes remarkable when the Al content is 0.001% or more, the Al content is preferably 0.001% or more. However, if the Al content exceeds 0.10%, the viscosity of the molten metal becomes too high, and conversely, spatter increases and defects such as poor fusion increase without bead spreading. Therefore, when Al is contained, the Al content is preferably 0.10% or less. The Al content is more preferably 0.002-0.090%.
　Ca：0.010％以下
　Caは、高温割れの抑制に寄与する元素である。また、Caは、溶融金属中でSと結合し、高融点の硫化物CaSを形成することで、高温割れを抑制する。このような効果は、Caの0.001％以上の含有で顕著となる。一方、Ca含有量が0.010％を超えると、溶接時にアークに乱れが生じ、安定な溶接が困難となる。そのため、Caを含有させる場合、Ca含有量は0.010％以下が好ましい。なお、Ca含有量は、より好ましくは0.002～0.008％である。 Ca: 0.010% or less Ca is an element that contributes to the suppression of hot cracking. In addition, Ca combines with S in the molten metal to form sulfide CaS with a high melting point, thereby suppressing hot cracking. Such an effect becomes remarkable when the content of Ca is 0.001% or more. On the other hand, when the Ca content exceeds 0.010%, arc disturbance occurs during welding, making stable welding difficult. Therefore, when Ca is contained, the Ca content is preferably 0.010% or less. Incidentally, the Ca content is more preferably 0.002 to 0.008%.
　REM：0.020％以下
　REMも、Caと同様、高温割れの抑制に寄与する元素である。また、REMは、強力な脱酸剤であり、溶接金属中でREM酸化物の形態で存在する。REM酸化物は凝固時の核生成サイトとなることで、溶接金属の凝固形態を変化させ、高温割れの抑制に寄与する。このような効果は、REMの0.001％以上の含有で顕著となる。しかし、REM含有量が0.020％を超えると、アークの安定性が低下する。そのため、REMを含有させる場合、REM含有量は0.020％以下が好ましい。なお、REM含有量は、より好ましくは0.002～0.016％である。 REM: 0.020% or less REM, like Ca, is an element that contributes to the suppression of hot cracking. REM is also a strong deoxidizing agent and exists in the form of REM oxides in the weld metal. REM oxides act as nucleation sites during solidification, thereby changing the solidification morphology of the weld metal and contributing to the suppression of hot cracking. Such an effect becomes remarkable when the content of REM is 0.001% or more. However, when the REM content exceeds 0.020%, arc stability decreases. Therefore, when REM is contained, the REM content is preferably 0.020% or less. The REM content is more preferably 0.002-0.016%.
　上記した成分以外の残部は、Feおよび不可避的不純物である。なお、不可避的不純物としては、Bi、Sn、Sb等が例示でき、合計で0.2％以下であれば許容できる。 The balance other than the above components is Fe and unavoidable impurities. Examples of unavoidable impurities include Bi, Sn, Sb, etc., and a total content of 0.2% or less is permissible.
　また、上記した溶接金属組成と、上記した溶接金属組織と、を有するT継手の溶接金属は、例えば、溶接材料および溶接条件を調整して多層盛溶接を行って形成することができる。 Also, the weld metal of the T-joint having the above weld metal composition and the above weld metal structure can be formed, for example, by adjusting the welding material and welding conditions and performing multi-layer welding.
　溶接方法としては、常用の、ガスメタルアーク溶接法が好適である。 As a welding method, gas metal arc welding, which is commonly used, is suitable.
　使用するソリッドワイヤは、上記した溶接金属組成と、上記した溶接金属組織と、を有するT継手の溶接金属が形成できるように、
　質量％で、C：0.10～0.70％、Si：0.10～1.00％、Mn：15.00～28.00％、P：0.030％以下、S：0.015％以下、Ni：1.00～5.00％、Cr：0.50～4.00％、Mo：2.00％以下、N：0.150％以下およびO：0.050％以下であり、
　任意に、
（ａ）V：0.10％以下、Ti：0.10％以下およびNb：0.10％以下のうちから選んだ１種または２種以上、
　ならびに
（ｂ）Cu：1.00％以下、Al：0.10％以下、Ca：0.010％以下およびREM：0.020％以下のうちから選んだ１種または２種以上
のうちの少なくとも一方を含有し、
　残部がFe及び不可避的不純物からなる、ワイヤ組成を有するワイヤとすることが好ましい。 The solid wire to be used has the above-described weld metal composition and the above-described weld metal structure so that the weld metal of the T-joint can be formed.
% by mass, C: 0.10-0.70%, Si: 0.10-1.00%, Mn: 15.00-28.00%, P: 0.030% or less, S: 0.015% or less, Ni: 1.00-5.00%, Cr: 0.50-4.00% , Mo: 2.00% or less, N: 0.150% or less, and O: 0.050% or less,
optionally,
(a) one or more selected from V: 0.10% or less, Ti: 0.10% or less, and Nb: 0.10% or less;
and (b) Cu: 1.00% or less, Al: 0.10% or less, Ca: 0.010% or less, and REM: 0.020% or less.
The wire preferably has a wire composition in which the balance is Fe and unavoidable impurities.
　そして、上記したワイヤ組成を有するワイヤを用いて、シールドガス中で、ガスメタルアーク溶接を行い、多層盛溶接金属を形成することが好ましい。なお、溶接条件は、下向き姿勢で、電流：150～450A（DCEP）、電圧：20～40V、溶接速度：15～60cm/min、パス間温度：100～200℃、および、シールドガス：80体積％Ar－20体積％CO2を同時に満足する条件とすることが好ましい。なお、溶接金属の強度調整のために、１パスの溶接入熱を1.0～3.0kJ/mmの範囲に調整することが好ましい。
　また、溶接では、図５に示すような、接合部材１に、所定の角度（40°）を有する開先を付与してもよい。 Then, using a wire having the wire composition described above, gas metal arc welding is preferably performed in a shielding gas to form a multi-layer weld metal. The welding conditions are downward position, current: 150 to 450 A (DCEP), voltage: 20 to 40 V, welding speed: 15 to 60 cm/min, interpass temperature: 100 to 200°C, and shield gas: 80 volumes. It is preferable to satisfy the conditions of %Ar-20% by volume CO 2 at the same time. In order to adjust the strength of the weld metal, it is preferable to adjust the welding heat input for one pass within the range of 1.0 to 3.0 kJ/mm.
Moreover, in welding, as shown in FIG. 5, the joining member 1 may be provided with a groove having a predetermined angle (40°).
　以下、さらに実施例に基づき、さらに本発明を説明する。 The present invention will be further described below based on examples.
　表２に示す板厚twの降伏強さ：355～460N/mm2（MPa）級厚鋼板を接合部材１として、表２に示す板厚tfの降伏強さ：355～460N/mm2（MPa）級厚鋼板を被接合部材２として用いた。接合部材１の端面を被接合部材２の表面に突き合せ、これらを溶接して、図４（ａ）、（ｂ）および（ｃ）に示す形状となる実構造サイズの大型溶接継手９を作製した。なお、被接合部材は、厚鋼板（母材のみ、表２中の種類を「母材」と表記）（図４（ａ））または突合せ溶接継手を有する厚鋼板（表２中の種類を「継手」と表記）（図４（ｂ）および（ｃ））とし、接合部材は、厚鋼板（母材のみ、表２中の種類を「母材」と表記）（図４（ａ）および（ｂ））、または突合せ溶接継手を有する厚鋼板（表２中の種類を「継手」と表記）（図４（ｃ））とした。なお、突合せ溶接継手は、表２に示す溶接入熱の、１パス大入熱エレクトロガスアーク溶接（SEGARCおよび２電極SEGARC）または多層盛炭酸ガス溶接（多層CO2）により作製した。 Yield strength at plate thickness tw shown in Table 2: 355 to 460N/mm 2 (MPa) grade thick steel plate as joint member 1, yield strength at plate thickness tf shown in Table 2: 355 to 460N/mm 2 (MPa ) class thick steel plate was used as the member 2 to be joined. The end surface of the member to be joined 1 is butted against the surface of the member to be joined 2, and these are welded to produce a large welded joint 9 of the actual size having the shape shown in FIGS. did. The member to be joined is a thick steel plate (only the base material, the type in Table 2 is indicated as "base material") (Fig. 4 (a)) or a thick steel plate having a butt weld joint (the type in Table 2 is "Joint") (Figs. 4(b) and (c)), and the joining member is a thick steel plate (only the base material, the type in Table 2 is indicated as "base material") (Fig. 4(a) and ( b)), or thick steel plates with butt-welded joints (types in Table 2 are indicated as "joints") (Fig. 4(c)). The butt-welded joints were produced by one-pass high-heat-input electrogas arc welding (SEGARC and two-electrode SEGARC) or multi-layer carbon dioxide gas welding (multi-layer CO 2 ) with welding heat inputs shown in Table 2.
　また、接合部材１と被接合部材２との溶接は、表１に示す溶接金属組成、ならびに、表２に示す溶接金属組織、硬さおよびLとなるように、ガスメタルアーク溶接（GMAW）により、溶接材料、ならびに、溶接入熱およびシールドガス等の溶接条件を変化させて行い、T継手を作製した。溶接材料は、所望の溶接金属組成となるように調整した、径：1.2mmのソリッドワイヤとした。なお、溶接条件は、下向き姿勢で、電流：150～450A（DCEP）、電圧：20～40V、溶接速度：15～60cm/min、パス間温度：100～200℃、シールドガス：80体積％Ar－20体積％CO2の条件とした。また、所定範囲の溶接金属硬さを確保するため、１パス溶接入熱量：1.0～3.0kJ/mmの範囲に調整した。 Welding of the joining member 1 and the member to be joined 2 was performed by gas metal arc welding (GMAW) so that the weld metal composition shown in Table 1 and the weld metal structure, hardness and L shown in Table 2 were obtained. , welding materials, and welding conditions such as welding heat input and shielding gas were varied to fabricate T-joints. The welding consumable was a solid wire with a diameter of 1.2 mm adjusted to the desired weld metal composition. The welding conditions are downward position, current: 150 to 450A (DCEP), voltage: 20 to 40V, welding speed: 15 to 60cm/min, interpass temperature: 100 to 200°C, shield gas: 80% by volume Ar. The condition was -20 vol% CO 2 . In addition, in order to ensure the hardness of the weld metal within a predetermined range, the heat input for one-pass welding was adjusted within the range of 1.0 to 3.0 kJ/mm.
　なお、一部の溶接継手（T継手）では、接合部材１と被接合部材２との間に隙間１４を設けた。また、一部の溶接継手（T継手）では、接合部材１に図５に示すような開先を設けて溶接した。 In some welded joints (T joints), a gap 14 was provided between the joining member 1 and the joined member 2. In some welded joints (T-joints), the joining member 1 was welded with a groove as shown in FIG.
　得られたT継手の溶接金属から試験片を採取した。採取した試験片を用いて、常法に従う化学分析法を行い、溶接金属組成を測定した。結果を表２に示す。 A test piece was taken from the weld metal of the obtained T joint. Using the sampled test piece, a chemical analysis method according to a conventional method was performed to measure the composition of the weld metal. Table 2 shows the results.
　また、採取した試験片を用いて、常法に従い、EBSD法による相分析でオーステナイト相およびフェライト相を同定し、溶接金属組織における各相の面積率を算出した。結果を表２に示す。 In addition, using the sampled test pieces, the austenite phase and ferrite phase were identified by phase analysis by the EBSD method according to the usual method, and the area ratio of each phase in the weld metal structure was calculated. Table 2 shows the results.
　また、採取した試験片を用いて、ＪＩＳ　Ｚ　２２４４－１（２０２０）に準拠して溶接金属硬さを測定した。結果を表２に示す。 In addition, the weld metal hardness was measured according to JIS Z 2244-1 (2020) using the sampled test pieces. Table 2 shows the results.
　ついで、得られた大型溶接継手９を用いて、図４に示す超大型構造モデル試験体を作製し、脆性亀裂伝播停止試験を実施した。超大型構造モデル試験体は、大型溶接継手９の被接合部材２の下方に仮付け溶接８で、被接合部材２と同じ板厚の鋼板を溶接した。また、被接合部材２に機械ノッチ７を設けた。 Next, using the obtained large welded joint 9, a super-large structural model specimen shown in Fig. 4 was produced, and a brittle crack arrest test was performed. For the ultra-large structural model specimen, 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 . In addition, a mechanical notch 7 is provided in the member 2 to be joined.
　なお、図４（ｂ）に示す超大型構造モデル試験体では、被接合部材２の突合せ溶接継手部１１を接合部材１と直交するように作製した。また、図４（ｃ）に示す超大型構造モデル試験体では、被接合部材２の突合せ溶接継手部１１と接合部材１の突合せ溶接継手部１２とを交差させた。そして、機械ノッチ７の先端を突合せ溶接継手部１１のBOND部、または溶接金属WMとなるように加工した。 In addition, in the ultra-large structural model specimen shown in FIG. 4(c), the butt-welded joint 11 of the member to be joined 2 and the butt-welded joint 12 of the joining member 1 were crossed. Then, the tip of the mechanical notch 7 was machined to become the BOND portion of the butt weld joint portion 11 or the weld metal WM.
　また、脆性亀裂伝播停止試験は、機械ノッチ７に打撃を与え脆性亀裂を発生させ、伝播した脆性亀裂が、溶接金属（WM）で停止するか否かを調査した。いずれの試験も、応力243～283Ｎ/mm2、温度：－10℃の条件で実施した。応力243Ｎ/mm2は、船体に適用されている降伏強さ355Ｎ/mm2級鋼板の最大許容応力相当の値、応力257Ｎ/mm2は、船体に適用されている降伏強さ390Ｎ/mm2級鋼板の最大許容応力相当の値、応力283Ｎ/mm2は、船体に適用されている降伏強さ460Ｎ/mm2級鋼板の最大許容応力相当の値であり、試験応力は接合部材の降伏強さに応じて最大許容応力相当に設定した。温度－10℃は船舶の設計温度である。 In the brittle crack arrest test, the machine notch 7 was hit to generate a brittle crack, and it was investigated whether the propagated brittle crack would stop at the weld metal (WM). 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/ mm2 , the value equivalent to the maximum allowable stress of class steel plates, is the value equivalent to the maximum allowable stress of 460N/ mm2 class steel plates with a yield strength applied to ship hulls. It was set to correspond to the maximum allowable stress depending on the The temperature of -10°C is the design temperature for ships.
　得られた結果を表３に示す。 Table 3 shows the results obtained.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-I000003
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-I000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　発明例はいずれも、脆性亀裂が被接合部材２を伝播したのち、溶接金属５に突入して停止した。一方、比較例ではいずれも、脆性亀裂は溶接金属５で停止することなく、接合部材１に伝播した。比較例では、溶接金属５で脆性亀裂の伝播を阻止することはできなかった。 In all invention examples, the brittle crack propagated through the joined member 2 and then entered the weld metal 5 and stopped. On the other hand, in all comparative examples, the brittle crack propagated to the joint member 1 without stopping at the weld metal 5 . In the comparative example, weld metal 5 could not prevent the propagation of brittle cracks.
１　　接合部材
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　未溶着部の幅 1 Joined member 2 Joined member 3 Weld leg length 4 Unwelded portion 5 Weld metal 7 Machine notch 8 Tack weld 9 Large weld joint 11 Butt weld joint of joined member 12 Butt weld joint of joined member 13 Weld width 14 Gap 15 Spacer 16 Width of unwelded part

Claims (15)

  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、前記接合部材と前記被接合部材とを接合するT継手を備える、溶接構造体であって、
    　前記T継手の溶接脚長および溶着幅のうちの長い方の値であるLが16mm以上であり、
    　前記T継手の溶接金属が、
    　　質量％で、C：0.10～0.70％、Si：0.10～1.00％、Mn：15.00～28.00％、P：0.030％以下、S：0.015％以下、Ni：1.00～5.00％、Cr：0.50～4.00％、Mo：2.00％以下、N：0.150％以下およびO：0.050％以下であり、残部がFe及び不可避的不純物である、溶接金属組成と、
    　　オーステナイト相が面積％で80％以上である、溶接金属組織と、を有する、溶接構造体。     A welded structure comprising a T-joint in which an end surface of a joining member is butted against a surface of a member to be joined having a plate thickness of 50 mm or more, and which joins the member to be joined and the member to be joined,
    L, which is the longer value of the weld leg length and weld width of the T joint, is 16 mm or more,
    The weld metal of the T joint is
    % by mass, C: 0.10-0.70%, Si: 0.10-1.00%, Mn: 15.00-28.00%, P: 0.030% or less, S: 0.015% or less, Ni: 1.00-5.00%, Cr: 0.50-4.00% , Mo: 2.00% or less, N: 0.150% or less and O: 0.050% or less, the balance being Fe and unavoidable impurities;
    A welded structure having a weld metallographic structure in which the austenitic phase is 80% or more by area.
  2. 　前記溶接金属組成が、さらに、質量％で、
    （ａ）V：0.10％以下、Ti：0.10％以下およびNb：0.10％以下のうちから選んだ１種または２種以上、
    　ならびに
    （ｂ）Cu：1.00％以下、Al：0.10％以下、Ca：0.010％以下およびREM：0.020％以下のうちから選んだ１種または２種以上
    のうちの少なくとも一方を含有する、請求項１に記載の溶接構造体。     The weld metal composition is further, in mass %,
    (a) one or more selected from V: 0.10% or less, Ti: 0.10% or less, and Nb: 0.10% or less;
    and (b) Cu: 1.00% or less, Al: 0.10% or less, Ca: 0.010% or less, and REM: 0.020% or less. Welded structure according to.
  3. 　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未溶着部が存在し、かつ、前記接合部材の板厚に対する前記未溶着部の幅の比率である未溶着比率Yが30％以上である、請求項１に記載の溶接構造体。 An unwelded portion exists on the surface of the T joint where the end surface of the joining member and the surface of the member to be joined are butted against each other, and the unwelded portion is a ratio of the width of the unwelded portion to the plate thickness of the joining member. Welded structure according to claim 1, wherein the ratio Y is 30% or more.
  4. 　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未溶着部が存在し、かつ、前記接合部材の板厚に対する前記未溶着部の幅の比率である未溶着比率Yが30％以上である、請求項２に記載の溶接構造体。 An unwelded portion exists on the surface of the T joint where the end surface of the joining member and the surface of the member to be joined are butted against each other, and the unwelded portion is a ratio of the width of the unwelded portion to the plate thickness of the joining member. Welded structure according to claim 2, wherein the ratio Y is 30% or more.
  5. 　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に記載の溶接構造体。 The welded structure according to claim 1, wherein said members to be joined have a butt weld joint portion so as to intersect said members to be joined.
  6. 　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２に記載の溶接構造体。 The welded structure according to claim 2, wherein the members to be joined have a butt weld joint portion so as to intersect the members to be joined.
  7. 　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３に記載の溶接構造体。 The welded structure according to claim 3, wherein the members to be joined have a butt weld joint portion so as to intersect the members to be joined.
  8. 　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４に記載の溶接構造体。 The welded structure according to claim 4, wherein the members to be joined have a butt weld joint portion so as to intersect the members to be joined.
  9. 　前記接合部材が、突合せ溶接継手部を有し、該接合部材の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、前記接合部材を、配設してなる、請求項５に記載の溶接構造体。 The joining member has a butt-welded joint portion, and the joining member is arranged so that the butt-welded joint portion of the joining member and the butt-welded joint portion of the member to be welded intersect. Item 6. The welded structure according to item 5.
  10. 　前記接合部材が、突合せ溶接継手部を有し、該接合部材の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、前記接合部材を、配設してなる、請求項６に記載の溶接構造体。 The joining member has a butt-welded joint portion, and the joining member is arranged so that the butt-welded joint portion of the joining member and the butt-welded joint portion of the member to be welded intersect. The welded structure according to Item 6.
  11. 　前記接合部材が、突合せ溶接継手部を有し、該接合部材の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、前記接合部材を、配設してなる、請求項７に記載の溶接構造体。 The joining member has a butt-welded joint portion, and the joining member is arranged so that the butt-welded joint portion of the joining member and the butt-welded joint portion of the member to be welded intersect. The welded structure according to Item 7.
  12. 　前記接合部材が、突合せ溶接継手部を有し、該接合部材の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、前記接合部材を、配設してなる、請求項８に記載の溶接構造体。 The joining member has a butt-welded joint portion, and the joining member is arranged so that the butt-welded joint portion of the joining member and the butt-welded joint portion of the member to be welded intersect. Item 9. The welded structure according to Item 8.
  13. 　前記接合部材の板厚が50mm以上である、請求項１ないし１２のいずれかに記載の溶接構造体。 The welded structure according to any one of claims 1 to 12, wherein the plate thickness of the joining member is 50 mm or more.
  14. 　前記接合部材と前記被接合部材との間の隙間が10mm以下である、請求項１ないし１２のいずれかに記載の溶接構造体。 The welded structure according to any one of claims 1 to 12, wherein the gap between the joining member and the member to be joined is 10 mm or less.
  15. 　前記接合部材と前記被接合部材との間の隙間が10mm以下である、請求項１３に記載の溶接構造体。
          14. The welded structure according to claim 13, wherein the gap between the joining member and the member to be joined is 10 mm or less.
PCT/JP2022/023799 2021-06-15 2022-06-14 Welded structure WO2022265011A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013038685A1 (en) * 2011-09-13 2013-03-21 Ｊｆｅスチール株式会社 Welded structure
JP2017502842A (en) * 2013-12-06 2017-01-26 ポスコＰｏｓｃｏ High strength weld joint with excellent cryogenic impact toughness and flux cored arc welding wire for this purpose
JP2018059190A (en) * 2016-09-30 2018-04-12 株式会社神戸製鋼所 Steel component, manufacturing method thereof, and steel sheet for steel component
WO2020138490A1 (en) * 2018-12-28 2020-07-02 日鉄ステンレス株式会社 Weld structure and method for producing same

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4074524B2 (en) 2003-01-31 2008-04-09 新日本製鐵株式会社 Welded structure with excellent brittle fracture resistance
JP5144053B2 (en) 2006-05-12 2013-02-13 Ｊｆｅスチール株式会社 Welded structure with excellent brittle crack propagation stop properties
CN103796786B (en) 2011-09-13 2015-04-22 杰富意钢铁株式会社 Welded structure
JP5408396B1 (en) 2012-05-10 2014-02-05 Ｊｆｅスチール株式会社 Welded structure
WO2016143354A1 (en) 2015-03-12 2016-09-15 Ｊｆｅスチール株式会社 Welded structure
KR102258423B1 (en) 2016-06-16 2021-06-03 제이에프이 스틸 가부시키가이샤 Welded structure having excellent brittle crack arrestability
TW202022137A (en) * 2018-12-11 2020-06-16 日商日本製鐵股份有限公司 High-strength steel plate with excellent formability, toughness and weldability, and production method thereof having a microstructure including more than 20% of acicular ferrite and more than 10% of martensite

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013038685A1 (en) * 2011-09-13 2013-03-21 Ｊｆｅスチール株式会社 Welded structure
JP2017502842A (en) * 2013-12-06 2017-01-26 ポスコＰｏｓｃｏ High strength weld joint with excellent cryogenic impact toughness and flux cored arc welding wire for this purpose
JP2018059190A (en) * 2016-09-30 2018-04-12 株式会社神戸製鋼所 Steel component, manufacturing method thereof, and steel sheet for steel component
WO2020138490A1 (en) * 2018-12-28 2020-07-02 日鉄ステンレス株式会社 Weld structure and method for producing same

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