WO2012008055A1 - Welded joint and welded structure having excellent brittle crack propagation resistance - Google Patents

Welded joint and welded structure having excellent brittle crack propagation resistance Download PDF

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Publication number
WO2012008055A1
WO2012008055A1 PCT/JP2010/062277 JP2010062277W WO2012008055A1 WO 2012008055 A1 WO2012008055 A1 WO 2012008055A1 JP 2010062277 W JP2010062277 W JP 2010062277W WO 2012008055 A1 WO2012008055 A1 WO 2012008055A1
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WIPO (PCT)
Prior art keywords
steel plate
brittle crack
welded joint
crack propagation
plate welded
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Application number
PCT/JP2010/062277
Other languages
French (fr)
Japanese (ja)
Inventor
石川　忠
昭 伊藤
健裕 井上
裕治 橋場
Original Assignee
新日本製鐵株式会社
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Application filed by 新日本製鐵株式会社 filed Critical 新日本製鐵株式会社
Priority to PCT/JP2010/062277 priority Critical patent/WO2012008055A1/en
Priority to KR1020107029823A priority patent/KR101185979B1/en
Priority to JP2010548310A priority patent/JP4818467B1/en
Publication of WO2012008055A1 publication Critical patent/WO2012008055A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
    • B23K31/02—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to soldering or welding
    • 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
    • B23K33/00—Specially-profiled edge portions of workpieces for making soldering or welding connections; Filling the seams formed thereby
    • B23K33/004—Filling of continuous seams
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/02—Seam welding; Backing means; Inserts
    • B23K9/025—Seam welding; Backing means; Inserts for rectilinear seams
    • 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
    • B23K9/16—Arc welding or cutting making use of shielding gas
    • B23K9/173—Arc welding or cutting making use of shielding gas and of a consumable electrode
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/50—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for welded joints
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • 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
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/18—Sheet panels
    • 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
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/02—Iron or ferrous alloys
    • B23K2103/04—Steel or steel alloys

Definitions

  • the present invention relates to a welded joint excellent in brittle crack propagation resistance that controls and suppresses the propagation of a brittle crack when a brittle crack occurs in the welded joint, and a welded structure having the welded joint.
  • a brittle crack occurs in a welded joint of a welded structure to which welding is applied using a thick steel plate, its propagation resistance can be improved by controlling and suppressing its propagation and improving safety. It relates to an excellent welded structure.
  • TEU wenty Fee Equivalent Unit
  • a container having a length of 20 feet represents an index of the loading capacity of the container ship.
  • Such a large container ship has a structure with a large upper opening without a partition wall in order to improve the loading capacity and cargo handling efficiency.
  • the strength of the hull outer plate and inner plate is ensured. Since it is necessary, the above high strength steel plates are used.
  • TMCP steel sheet (Thermo Mechanical Control Process: excellent in brittle fracture resistance characteristics) for the purpose of suppressing the occurrence of brittle cracks in welded joints and achieving the propagation stop (arrest) of brittle cracks. Thermal processing control) has been proposed.
  • the fracture toughness value which is a resistance value against the occurrence of brittle fracture, is improved, so that the possibility of the structure undergoing brittle fracture becomes extremely low in a normal use environment.
  • a brittle fracture occurs in the event of an earthquake, a collision between structures, a disaster, or the like, a brittle crack may propagate through the HAZ and cause a large fracture.
  • TMCP steel plates with a thickness of about 50 mm are used, and even if a brittle crack occurs in a welded joint, the brittle crack will be Therefore, it was thought that a brittle crack could be stopped at the base material if the arrest performance of the base material was ensured.
  • a steel plate having a larger thickness is required, and further, in order to simplify the structure, it is effective to increase the thickness of the steel plate. It has been required to use a high-strength steel plate having a high design stress.
  • a plate-like arrester material is welded so as to intersect the weld line.
  • a welded structure using a material having an optimized texture in a surface layer region having a thickness of 2% or more on the front and back surfaces (for example, Patent Document 2).
  • Patent Document 2 when the welded structure described in Patent Document 2 is applied to a large building, for example, a brittle crack that has propagated through a welded joint propagates through a welded joint that welds the arrester material to a steel sheet and enters the arrester material.
  • the brittle crack that propagated through the welded joint deviates to the base metal side at the position of the arrester material and the weld joint where the arrester material is welded to the steel plate, the fracture toughness of the base material is insufficient as described above. There is also a concern that the brittle crack propagates for a long time and the strength as a welded structure is significantly reduced.
  • the present invention has been made in view of the above problems, and even when a brittle crack occurs in a welded joint, it is possible to suppress the brittle crack from propagating through the welded joint or the base material, and a welded structure.
  • An object of the present invention is to provide a welded structure excellent in brittle crack propagation resistance that can prevent fracture of the steel.
  • At least one location of the steel plate welded joint is provided with a brittle crack propagation direction control unit that controls the propagation of a brittle crack generated in the steel plate welded joint,
  • the brittle crack propagation direction control part has an inclined bead formed by butt welding between a protrusion formed on one steel plate and the other steel plate facing it, The inclined bead extends in the longitudinal direction from the weld line of the steel plate welded joint, and is inclined at an angle in the range of 15 ° to 50 ° with respect to the longitudinal direction of the steel plate welded joint.
  • the inclined beads provided in the brittle crack propagation direction control unit have a height H (mm) along the longitudinal direction of the steel plate welded joint and a lateral width W in a direction intersecting the longitudinal direction of the steel plate welded joint.
  • H mm
  • W lateral width
  • Each dimension of (mm) satisfies the relationship expressed by the following formulas (1) and (2), and the steel plate welding having excellent brittle crack propagation resistance according to the above [1] Fittings. 2T ⁇ H (1) d + 50 ⁇ W (2)
  • T represents the plate
  • d represents the width
  • the steel plate has a brittle crack propagation stop characteristic Kca of at least a partial region of 6000 N / mm 1.5 or more, and the rear end of the inclined bead has at least a Kca of the steel plate of 6000 N / mm.
  • the steel plate is made of at least two or more small steel plates arranged in the longitudinal direction of the steel plate welded joint, and a small steel plate welded joint is formed by butt welding the small steel plates to each other.
  • the steel plate welded joint includes a horizontal bead formed on a rear end side of the inclined bead of the brittle crack propagation direction control unit extending from a weld line of the steel plate welded joint.
  • the brittle crack propagation property is characterized in that the brittle crack propagation direction control section according to any one of the above [1] to [5] is provided in at least one place of the steel plate welded joint. Excellent welded structure.
  • a portion including a weld metal portion and a weld heat affected zone is defined as a weld joint.
  • the brittle crack propagation stop characteristic Kca is a numerical value at the temperature at which the welded structure is used or at the design temperature.
  • a welded joint formed by butt-welding steel plates is butt-welded between a protrusion formed on one steel plate and the other steel plate facing it. Because the brittle crack propagation direction control part consisting of the inclined beads formed in this way is provided, even if a brittle crack occurs in the welded joint, the brittle crack propagating through the welded joint.
  • the brittle crack propagation direction control part can deflect the steel plate base metal to a part with high arrest performance, or the brittle crack propagation direction control part can prevent the brittle crack from propagating through the welded joint or the base material. Can be suppressed.
  • Such a welded structure according to the present invention is used for various types of welded structures such as large ships, building structures, civil engineering steel structures, etc., so that the welded structures can be increased in size and destroyed with high safety. Since the efficiency of welding in construction, the economics of steel materials, etc. are satisfied at the same time, the industrial effects are immeasurable.
  • FIG. 1 is a diagram illustrating the present invention, and is a plane showing a state in which a brittle crack propagation direction control unit having an inclined bead is provided in a part of a steel plate welded joint formed by welding steel plates together.
  • FIG. FIG. 2 is a schematic diagram for explaining the progress of a brittle crack when a brittle crack propagation direction control unit shown in FIG. 1 is provided in a part of a steel plate welded joint.
  • FIG. 3 is a schematic diagram for explaining the crack propagation characteristics of the steel plate welded joint and welded structure according to the present invention, and is an enlarged view of the main part of the steel plate welded joint and welded structure shown in FIG. FIG.
  • FIG. 4 is a schematic diagram illustrating a case where the steel plate welded joint and the welded structure according to the present invention are applied to a marine welded structure.
  • FIG. 5 is a view similar to FIG. 3 for explaining another example of the steel plate welded joint and welded structure according to the present invention.
  • FIG. 6 is a view similar to FIG. 3 for explaining another example of the steel plate welded joint and welded structure according to the present invention.
  • FIG. 7 is a view similar to FIG. 3 for explaining another example of the steel plate welded joint and welded structure according to the present invention.
  • FIG. 8 is a diagram for explaining a welded joint specimen used in an example of the present invention.
  • FIG. 9 is a diagram illustrating a tensile test method for evaluating the brittle crack propagation property in an example of the present invention.
  • a brittle crack generated in a steel plate welded joint mainly propagates in the longitudinal direction along the steel plate welded joint. For this reason, the brittle crack which arose in the steel plate welded joint becomes a starting point, and there existed a problem that there existed a possibility that a big fracture might arise in the whole welded structure.
  • the present inventors have further improved the brittle crack. It was found that it is important to optimize the shape of the member that controls propagation and the steel material characteristics. The basic principle of the present invention will be described with reference to FIGS.
  • a brittle crack propagation direction control unit 3 for controlling the propagation of a brittle crack generated in the steel plate welded joint is provided in the middle of the steel plate welded joint 1 formed by butt welding the steel plates 2 and 2.
  • the brittle crack propagation direction control unit 3 is provided with a protruding portion 4 on one steel plate butt welded, a notch portion 5 having a shape corresponding to the protruding portion 4 on the other steel plate, and butt-welding the two. Is formed.
  • the protruding portion 4 is inclined and protrudes from the end of the steel plate, and an inclined bead 31 that extends toward the inside of the steel plate is provided at the welded portion between the protruding portion 4 and the notch portion 5. It is formed continuously from the joint 1.
  • the propagation of the crack is controlled as follows. To do.
  • the brittle crack CR generated on one side in the longitudinal direction of the steel plate welded joint 1 (upper side in FIGS. 2A to 2E) propagates along the boundary between the steel plate 2 and the steel plate welded joint 1.
  • the crack CR reaches the inclined bead 31, the crack CR propagates along the boundary between the steel plate 2 and the inclined bead 31 as shown in FIG.
  • the base material part of 2 is reached.
  • the brittle crack propagation stop characteristic Kca of the steel plate 2 is high even if it enters the base metal part, the progress of the crack CR can be stopped there.
  • a crack may enter the protrusion 4 from the inclined bead.
  • the height of the protrusion is sufficient, or when the brittle crack propagation stop characteristic Kca of the base material forming the protrusion is sufficiently high, as shown in FIG.
  • the propagation of brittle cracks can be stopped inside.
  • the Kca of the brittle crack propagation direction control unit 3 is increased and the brittle crack propagation direction. If the height in the direction along the welded joint of the control unit 3 is sufficient, as shown in FIG. 2-f, the progress of the crack CR is stopped inside the brittle crack propagation direction control unit 3. can do.
  • the brittle crack CR is resistant as shown in FIG. It is assumed that the brittle crack propagation direction control unit 3 is penetrated, or the inclined bead is returned to the steel plate welded joint as shown in FIG. Further, when the Kca of the steel plate is low, it is also assumed that a brittle crack deviating from the inclined bead to the steel plate propagates through the steel plate as shown in FIG.
  • the present invention further examines the conditions of the base steel plate that inhibits the development of brittle cracks, the conditions of the brittle crack propagation direction control unit that controls the development of brittle cracks, and the like.
  • the base steel plate that inhibits the development of brittle cracks
  • the brittle crack propagation direction control unit that controls the development of brittle cracks
  • a steel plate welded joint 1 is formed by butt welding steel plates 2 and 2 having a brittle crack propagation stop characteristic Kca of the base material of 4000 N / mm 1.5 or more.
  • a form applied to this joint will be referred to as a welded structure A and described below.
  • a brittle crack propagation direction control unit 3 is provided in at least one location of the steel plate weld joint 1 in order to divert the propagation of the brittle crack generated in the steel plate weld joint toward the steel plate base material side.
  • the position where the brittle crack propagation direction control unit 3 is provided is preferably in the middle of a steel plate welded joint where crack generation / propagation is predicted when exposed to large fracture energy due to collision or earthquake.
  • the brittle crack propagation direction control unit 3 is provided with a protruding portion 4 on one steel plate butt welded, a notch portion 5 having a shape corresponding to the protruding portion 4 on the other steel plate, and butt-welding the two. Thus, it is formed between the steel plate joints 11 and 12.
  • the protruding portion 4 is inclined and protrudes from the end of the steel plate, and an inclined bead 31 that extends toward the inside of the steel plate is provided at the welded portion between the protruding portion 4 and the notch portion 5.
  • the inclined bead 31 is formed to be inclined at an angle in the range of 15 ° to 50 ° with respect to the longitudinal direction of the steel plate welded joint 1, and one end 32 a of the horizontal bead 32 is provided at the rear end 31 b of the inclined bead 31. The other end 32 b of the horizontal bead 32 is connected to the steel plate joint 12.
  • the steel plate 2 is made of a steel material having a brittle crack propagation stop characteristic Kca of 4000 N / mm 1.5 or more. From the viewpoint of further improving the brittle crack propagation resistance, it is preferably 6000 N / mm 1.5 or more. As long as the steel plate 2 satisfies the above Kca, the chemical composition, metal structure, and the like are not limited to specific ones, and in the fields of marine welded structures, building structures, civil engineering steel structures, etc. What has a conventionally well-known steel plate characteristic can be used.
  • C 0.01 to 0.18%
  • Si 0.01 to 0.5%
  • Mn 0.3 to 2.5%
  • P 0.01% or less
  • S 0
  • N 0.001 to 0.008%
  • B 0.0001 to 0.005%
  • the plate thickness of the steel plate 2 is preferably in the range of 25 mm to 150 mm. When the plate thickness of the steel plate 2 is within this range, it is possible to ensure the strength of the steel plate as a welded structure and to obtain excellent brittle crack propagation resistance. In particular, in a welded structure using a steel plate of 40 mm or more, there is no effective means for stopping the propagation of a brittle crack, and a welded structure using a steel plate having a plate thickness of 40 mm or more, more preferably 50 mm or more and 100 mm or less. In the body, the present invention is more effectively implemented.
  • the brittle crack propagation direction control unit 3 is formed of a welded joint provided on at least a part of the steel plate welded joint 1. In the example shown in FIG. 3, two steel plate joints 11 forming the steel plate welded joint 1, Between 12, a brittle crack propagation direction control unit 3 is provided.
  • the brittle crack propagation direction control unit 3 extends from the weld line L of the steel plate welded joint 1 (steel plate joint 11 in the illustrated example) and is 15 ° or more and 50 ° or less with respect to the longitudinal direction of the steel plate welded joint 1.
  • An inclined bead 31 inclined at an inclination angle ⁇ in the range is provided.
  • one end 32 a of the horizontal bead 32 is connected to the rear end 31 b of the inclined bead 31, and the other end 32 b of the horizontal bead 32 is connected to the steel plate joint 12.
  • the steel plate welded joint according to the present invention and the welded structure in which the steel plate welded joint is used include a brittle crack propagation direction control unit 3 as described above, so that a brittle crack is temporarily generated in the steel plate welded joint 1. Even in this case, the propagation direction of the brittle crack is controlled to prevent the crack from propagating through the welded joint 1 to separate the steel plates 2 welded to each other.
  • the inclined bead 31 extending from the top portion 31a disposed on the weld line L of the steel plate welded joint 11 is formed on the steel plate welded joint 1 (11, 12). It is preferable to incline at an angle ⁇ in the range of 15 ° to 50 ° with respect to the longitudinal direction.
  • the inclination angle of the inclined bead 31 within the above range, even when a brittle crack propagating through the steel plate welded joint 11 is generated, the crack is guided to propagate along the inclined bead 31 from the steel plate welded joint.
  • the steel plate 1 can be deflected stably toward the base material side.
  • the angle ⁇ of the inclined bead of the brittle crack propagation direction control unit is less than 15 °, even if the crack propagates along the inclined bead, the position of the crack that has passed through the inclined bead Since it is close to the position of the steel plate welded joint, which is the propagation path, the crack may enter the steel plate welded joint again and propagate. Further, when the angle ⁇ of the inclined bead exceeds 50 °, after the brittle crack propagated through the steel plate welded joint propagates along the inclined bead 31, it does not escape to the base metal side of the steel plate, and remains in the protrusion 4 as it is. The possibility of rushing increases.
  • the brittle crack since the brittle crack directly enters the brittle crack propagation direction control part, if the brittle crack propagation stop characteristic Kca of the projection 4 is not sufficient, the crack propagation is stopped. Without passing through the brittle crack propagation direction control unit, it may enter the steel plate welded joint and propagate again. Further, the angle ⁇ of the inclined bead of the brittle crack propagation direction control unit with respect to the longitudinal direction of the steel plate welded joint is 50 while securing the height H of the brittle crack propagation direction control unit in the range described below. If it exceeds 0 °, the width W of the brittle crack propagation direction control portion becomes too large, which is not realistic.
  • a more preferable range of the inclination angle ⁇ for guiding the brittle crack to propagate along the inclined beads 31 is 20 ° or more and 45 ° or less, and a more preferable range is 25 ° or more and 40 ° or less.
  • the horizontal bead 32 connecting the inclined bead 31 and the steel plate joint 12 has an angle ⁇ 2 (see FIG. 1-b) between the horizontal bead 32 and the steel plate joint 12 of 80 ° (preferably 90 °) or more and 110 °. What is necessary is just to form so that it may become the following ranges. If it is out of this range, there is a risk that the brittle crack may enter the protrusion 4 from the middle of the inclined bead or return to the steel plate joint as shown in FIG.
  • the protrusion 4 provided on the brittle crack propagation direction control unit 3 used in the steel plate welded joint 1 (welded structure A) of the present embodiment has a height H (mm) along the longitudinal direction of the steel plate welded joint.
  • the lateral width W (mm) protruding from the steel plate welded joint 1 preferably satisfies the relationship represented by the following formulas (1) and (2). 2T ⁇ H (1) d + 50 ⁇ W (2)
  • T (mm) represents the plate
  • the brittle crack propagation direction control unit 3 By setting the dimensional values of the inclined beads 31 provided in the brittle crack propagation direction control unit 3 as described above, even if the brittle crack propagates through the steel plate welded joint 1, the propagation of the crack The direction can be effectively diverted to the base material side of the steel plate 2 by the inclined beads. Further, even when a crack enters the protrusion 4, it is possible to stop the progress of the crack in the protrusion. If the relationship between the dimensional values of the brittle crack propagation direction control part does not satisfy the relationship expressed by the above equations (1) and (2), depending on the state of the crack generated in the steel plate welded joint, May enter the brittle crack propagation direction control section and propagate through the steel plate welded joint without deviating to the base metal side of the steel plate.
  • the height H is preferably 200 mm or more, or 250 mm or more, and more preferably 300 mm or more.
  • H / T is 2. 0 or more is preferable and 3.0 or more is more preferable.
  • the steel plate welded joint 1 and the welded structure A of the present embodiment Due to the above-described action, the steel plate welded joint 1 and the welded structure A of the present embodiment, even if a brittle crack occurs in the steel plate welded joint 1, causes the brittle crack to spread over the welded joint and the base material in a wide range. Since propagation can be suppressed, it is possible to prevent large-scale destruction from occurring.
  • the welded structure A in which the steel plate welded joint 1 of the present embodiment is used for example, to various welded structures such as a large ship, a building structure, and a civil engineering steel structure, a welded structure is obtained. It is possible to simultaneously satisfy the demands for increasing the size of the steel, the high safety against destruction, the high efficiency of welding in construction, the economic efficiency of steel materials, and the like.
  • the brittle crack propagation direction control unit is subject to cracking when exposed to large fracture energy due to impact or earthquake. It is a steel plate welded joint which is expected to be generated and propagated, and is provided at least one place in the middle of the steel plate welded joint formed by a steel plate having a brittle crack propagation stop characteristic Kca of 4000 N / mm 1.5 or more.
  • the brittle crack propagation direction control unit 3 is provided with a protruding portion 4 on one steel plate butt welded, a notch portion 5 having a shape corresponding to the protruding portion 4 on the other steel plate, and butt-welding the two. Is formed.
  • the welding order is not particularly limited, but after the steel plate welded joint 11 and the steel plate welded joint 12 are formed by welding first, the brittle crack propagation direction control unit 3 is formed by welding. It is common.
  • the electrogas arc welding method (EG welding method or two-electrode VEGA welding method (2VEGA) is used for welding to form the steel plate welded joints 11 and 12 from the viewpoint of welding efficiency. ), Etc.), semi-automatic carbon dioxide welding or manual welding may be applied to welding for forming the brittle crack propagation direction control unit 3 by applying high heat input welding such as the submerged arc welding method (SAW). preferable.
  • SAW submerged arc welding method
  • the welding method and the welding material for forming the steel plate welded joint 1 by butt welding the steel plates 2 are not particularly limited. Further, brittle crack propagation is suppressed as much as possible, and new fatigue cracks and brittle crack starting points are generated in the steel plate joints 11 and 12 and the brittle crack propagation direction control unit 3 forming the steel plate welded joint 1. In order to prevent this, it is preferable to completely fill each welded joint with a weld metal so that there are no weld defects. According to the above procedure, the steel plate welded joint 1 and the welded structure A having excellent brittle crack propagation properties according to the present embodiment as shown in FIG. 3 can be manufactured.
  • the ship structure 70 includes an aggregate (reinforcing material) 71, a deck plate (horizontal member) 72, a hull inner plate (vertical member) 73, and a hull outer plate 74.
  • the ship structure 70 of the example of illustration is a part of the longitudinal direction of the steel plate welded joint 1 (not shown in FIG. 4) formed by butt welding a plurality of steel plates 2 forming the hull inner plate 73.
  • the welding structure A of the present embodiment is provided. According to the ship structure 70 having the above-described configuration, by applying the configuration of the welded structure A of the present embodiment, even if a brittle crack propagating through a steel plate welded joint occurs, the brittle resistance The crack propagation direction control unit 3 can effectively control the propagation direction of the crack. Thereby, the brittle crack generated in the steel plate welded joint can be stably stopped, and it is possible to prevent the large-scale destruction from occurring in the hull inner plate 73 and consequently the ship structure 70.
  • the brittle crack propagation direction control unit 3 has a brittle crack propagation stop characteristic Kca of a part of the base material 20a, 20a of 4000 N / mm 1.
  • Kca a brittle crack propagation stop characteristic of a part of the base material 20a, 20a of 4000 N / mm 1.
  • the steel plate welded joint 1 is formed by butt welding the steel plates 20 and 20 which are 5 or more, and in this respect, the entire base material of the steel plate 2 has a brittle crack propagation stop characteristic Kca.
  • FIG. 5 shows an example in which the horizontal bead 32 of the brittle crack propagation direction control unit is in contact with the region 20a.
  • the crack that has escaped to the base material side of the steel plate 20 immediately stops in the region 20a of the steel plate 20, so that the steel plate welded joint 10 breaks. Moreover, it becomes possible to prevent large-scale destruction in the welded structure B. Moreover, as for the steel plate welded joint 10 and the welding structure B of this embodiment, it is more preferable that the region 20a has a brittle crack propagation stop characteristic Kca of 6000 N / mm 1.5 or more.
  • the welded structure C is an example in which a steel plate to be butt welded is formed by butt welding a plurality of small steel plates.
  • the steel plate welded joint 10A and the welded structure C of the present embodiment as shown in FIG. 6, at least two or more small steel plates (in which the steel plates 20A and 20A to be butt welded are arranged in the longitudinal direction of the steel plate welded joint 10A ( 6 and a pair of 23 and 24), and the small steel plates are butt welded to form small steel plate welded joints 25 and 26.
  • the horizontal bead formed in the rear-end 31b side of the inclination bead 31 of the brittle crack propagation direction control part 30 becomes a structure containing these small steel plate welded joints 25 and 26, and 10A of steel plate welded joints and welding are comprised.
  • the structure C is different from the steel plate welded joints 1 and 10 and the welded structures A and B of the first and second embodiments described above.
  • four small steel plates 21 to 24 are shown as small steel plates, and the small steel plate 21 and the small steel plate 22 are joined together by a small steel plate welded joint 25. And the small steel plate 24 are joined by a small steel plate welded joint 26.
  • the welded structure C is formed in a straight line by connecting small steel plate welded joints 25 and 26.
  • the brittle crack propagation stop characteristic Kca of the base material forming the small steel plate 22 and the small steel plate 24 is set to 4000 N / mm 1.5 or more,
  • the brittle crack propagation stop characteristic Kca of the small steel plate 21 and the small steel plate 23 is not particularly defined.
  • the brittle crack is inclined to the bead 31. And can be deflected to the base material side of the steel plate 20A at the position of the rear end 31b of the inclined bead 31 (see the two-dot chain line arrow in FIG. 6).
  • the brittle crack generated in the steel plate welded joint 10A is deviated to the small steel plate 21 side constituting the steel plate 20A.
  • the steel plate welded joint 10B and the welded structure D according to the fourth embodiment of the present invention will be described mainly with reference to FIG. 7.
  • the steel plate welded joint 10B and the welded structure D of the present embodiment are shown in FIG.
  • the steel plate 20B is made of at least two or more small steel plates (a set of symbols 31, 32 and a set of 33, 34 in FIG. 7) arranged in the longitudinal direction of the steel plate welded joint 10B.
  • a part of the configuration is common to the steel plate welded joint 10A and the welded structure C of the third embodiment in that small steel plate welded joints 35 and 36 are formed by butt welding the steel plates.
  • the brittle crack propagation stopping characteristics Kca of the base materials of all the small steel plates 31 to 34 constituting the steel plate 20B are set to 4000 N / mm 1.5 or more. Yes.
  • the brittle crack is inclined to the bead 31. Can be displaced to the base material side of the steel plate 20B at the position of the apex 31a (see the two-dot chain line arrow in FIG. 7). Moreover, since Kca of the small steel plates 31 and 33 is also high, even when the propagation direction of the brittle crack does not change in the direction along the inclined bead 31, the crack that has entered the base material of the small steel plate 31 or the protruding portion 4, It can be stopped by the arrest performance of the small steel plates 31 and 33.
  • the propagation of the brittle crack can be stopped in the middle of the protrusion 4 as shown in FIG. As a result, it is possible to prevent large-scale destruction from occurring in the steel plate welded joint 10B and the welded structure D.
  • EG General electrogas arc welding method
  • VEGA Single electrode electrogas arc welding method provided with the electrode swing mechanism
  • 2VEGA Two electrode electrogas arc welding method provided with the electrode swing mechanism
  • SEG single electrode electrogas arc welding method with electrode swing mechanism
  • SAW submerged arc welding method
  • CO 2 carbon dioxide arc welding method
  • SMAW coated arc welding method.
  • the brittle crack generation part was cooled to ⁇ 60 ° C. or lower, but the temperature of the steel plate welded joint 1 as the brittle crack propagation part was set to ⁇ 10 ° C., which is a general design temperature of ships.
  • the window frame 81 was provided in the steel plate joint 12, and the test which penetrates a brittle crack into the brittle crack propagation direction control part 3 from the lower side was also done.
  • the brittle crack After the brittle crack has reached the brittle crack propagation direction control section, the brittle crack entered the projection of the steel sheet without following the control section, and immediately stopped at the projection (form of FIG. 2-b ). [C] ... After the brittle crack reaches the brittle crack propagation direction control part, it enters and propagates into the protrusion of the steel sheet without following the control part, returns to the steel plate welded joint, and again connects the steel welded joint. Propagated (form of FIG. 2-c). [D] ... After the brittle crack reaches the brittle crack propagation direction control part, the crack propagates along the control part, returns as it is along the steel plate welded joint, and propagates again through the steel plate welded joint (Fig. 2-d form).
  • Table 1 shows a list of the chemical composition of the steel plate used in this example, the steel plate manufacturing conditions, and the brittle crack propagation stopping property Kca (N / mm 1.5 ) of the base material, and the steel plate welded joint 1 is formed.
  • Welding conditions, the shape of the brittle crack propagation direction control unit 3, the welding conditions when forming a small steel plate welded joint adjacent to the brittle crack propagation direction control unit 3, and the evaluation results of the propagation of the brittle crack The list is shown in Tables 2-5.
  • Invention Examples 1 to 19 shown in Tables 2 to 5 are examples relating to the steel plate welded joint 1 and the welded structure A of the first embodiment shown in FIG. 3, and Invention Examples 20 to 25 are shown in FIG.
  • Invention Examples 26-30 are applied to the steel plate welded joint 10A and welded structure C of the third embodiment, and Examples 31 to 30 are applied to the steel plate welded joint 10B and welded structure D of the fourth embodiment shown in FIG. ⁇ 33 are examples relating to the steel plate welded joint 10 and the welded structure B of the second embodiment shown in FIG.
  • Inventive Examples 14, 22, and 28 are examples in which the crack entered the brittle crack propagation direction control unit 3 from the lower side.
  • Comparative Examples 1 and 2 shown in Table 2 are examples having the same structure as the welded structure A, Comparative Examples 3 and 4 have the same structure as the welded structure B, and Comparative Examples 5 and 6 Comparative structures 7 to 9 are examples having the same structure as the welded structure D, and Comparative Examples 7 to 9 are examples having the same structure as the welded structure D.
  • Comparative Example 6 is an example in which a crack entered from the lower side.
  • the angle ⁇ of the inclined bead 31 of the brittle crack propagation direction control unit 3 is 30 ° or less with respect to the longitudinal direction of the steel plate welded joint 1.
  • the crack enters the base material (projection 4) of the steel plate 2 from the brittle crack propagation direction control unit 3 and stops at the steel plate 2.
  • the brittle crack that reached the brittle crack propagation direction control unit 3 propagated along the control unit, and then entered the base material of the steel plate and immediately stopped. It is.
  • each of the steel plate welded joints and welded structures of Examples 1-33 of the present invention had a predetermined brittle crack propagation resistance.
  • Comparative Example 2 the angle of the inclined bead is insufficient, and the width W does not satisfy the above formula (2).
  • Comparative Example 6 the arrest performance of the base material of the steel plate is insufficient. This is an example in which a brittle crack whose propagation direction has been changed along the brittle crack propagation direction control unit propagates again through the steel plate welded joint and becomes [d].
  • Comparative Examples 3 to 5 since the arrest performance of the base material of the steel plate was insufficient, the steel plate was able to control the propagation direction of the brittle crack in the brittle crack propagation direction control unit. This is an example in which a brittle crack that has entered the base metal propagates as it is and becomes [e].
  • the steel plate welded joint and welded structure of the present invention can suppress the propagation of the crack through the welded joint and the base material even when a brittle crack occurs in the welded joint. It is clear that the body can be prevented from breaking and is excellent in brittle crack propagation resistance.

Abstract

A steel plate welded joint (1) formed by butt-welding steel plates (2, 2) in which brittle crack arresting properties (Kca) of at least a part of the area of a base metal are 4000 N/mm1.5 or more, and a welded structure (A) including the welded joint, wherein a brittle crack propagation resistance direction control unit (3) is provided to at least one place of the steel plate welded joint; wherein the brittle crack propagation resistance direction control unit has a projection (4) formed on one of the steel plates, and an inclination bead (31) between the projection and the other thereof; and wherein the inclination bead extends from a weld line (L) of the steel plate welded joint, is inclined at an angle in a range of 15˚-50˚inclusive relative to the longitudinal direction of the steel plate welded joint, and is formed so as to face the area in which the Kca of the steel plates is 4000 N/mm1.5 or more. As a result, even if brittle cracks occur in the welded joint, the brittle cracks can be prevented from propagating through the welded joint or the base metal.

Description

耐脆性き裂伝播性に優れた溶接継手及び溶接構造体Welded joint and welded structure excellent in brittle crack propagation resistance
　本発明は、溶接継手に脆性き裂が発生した場合に、脆性き裂の伝播を制御、抑制する耐脆性き裂伝播性に優れた溶接継手、及びその溶接継手を有する溶接構造体に関する。
　特に、厚鋼板を用いて溶接を適用した溶接構造物の溶接継手において脆性き裂が発生した場合でも、その伝播を制御、抑制して安全性を向上させることができる耐脆性き裂伝播性に優れた溶接構造体に関する。 The present invention relates to a welded joint excellent in brittle crack propagation resistance that controls and suppresses the propagation of a brittle crack when a brittle crack occurs in the welded joint, and a welded structure having the welded joint.
In particular, even when a brittle crack occurs in a welded joint of a welded structure to which welding is applied using a thick steel plate, its propagation resistance can be improved by controlling and suppressing its propagation and improving safety. It relates to an excellent welded structure.
　近年、大型コンテナ船やバルクキャリア等の船舶用溶接構造体、建築構造物、土木鋼構造物に代表される溶接構造体においては、脆性き裂等の破壊に対する高い安全性が求められるようになっている。特に、コンテナ船は大型化が顕著であり、例えば、６０００ＴＥＵ以上の大型コンテナ船が製造されるようになり、船殻外板の鋼板が厚肉化並びに高強度化し、板厚７０ｍｍ以上で降伏強度３９０Ｎ／ｍｍ２級以上の鋼板が用いられるようになっている。
　ここで、ＴＥＵ（Ｔｗｅｎｔｙ　ｆｅｅｔ　Ｅｑｕｉｖａｌｅｎｔ　Ｕｎｉｔ）とは、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している。
　このような大型コンテナ船は、積載能力や荷役効率の向上のため、仕切り壁を無くして上部開口部を大きく確保した構造とされており、特に、船殻外板や内板の強度を確保する必要があるため、上記のような高強度鋼板が用いられている。 In recent years, welded structures represented by marine welded structures such as large container ships and bulk carriers, building structures, and civil engineering steel structures have been required to have high safety against fractures such as brittle cracks. ing. In particular, the size of container ships has increased significantly. For example, large container ships of 6000 TEU or more have been manufactured, and the steel plate of the hull shell has become thicker and stronger, and the yield strength has been increased to a thickness of 70 mm or more. Steel plates of 390 N / mm grade 2 or higher are used.
Here, TEU (Twenty Fee Equivalent Unit) represents the number converted into a container having a length of 20 feet, and represents an index of the loading capacity of the container ship.
Such a large container ship has a structure with a large upper opening without a partition wall in order to improve the loading capacity and cargo handling efficiency. In particular, the strength of the hull outer plate and inner plate is ensured. Since it is necessary, the above high strength steel plates are used.
　上述のような溶接構造物を建造する際、建造コストの低減や建造効率向上を目的として、大入熱溶接（例えば、エレクトロガスアーク溶接）が広く適用されている。小さな入熱量の適用による多層盛溶接では、特に、鋼板の板厚が増すほど溶接工数が著しく増加するため、極限まで大入熱で溶接を行なうことが要求される。しかしながら、鋼板の溶接に大入熱溶接を適用した場合、溶接熱影響部（ＨＡＺ：Ｈｅａｔ　Ａｆｆｅｃｔｅｄ　Ｚｏｎｅ）の靭性が低下し、ＨＡＺの幅も増大するため、脆性破壊に対する破壊靭性値が低下する傾向にある。 When constructing a welded structure as described above, large heat input welding (for example, electrogas arc welding) is widely applied for the purpose of reducing construction costs and improving construction efficiency. In multi-layer welding by application of a small amount of heat input, the number of welding processes increases remarkably as the plate thickness of the steel plate increases. Therefore, it is required to perform welding with high heat input to the limit. However, when high heat input welding is applied to the welding of steel plates, the toughness of the weld heat affected zone (HAZ: Heat Affected Zone) decreases and the width of the HAZ also increases, so the fracture toughness value against brittle fracture tends to decrease. It is in.
　このため、溶接継手において脆性き裂が発生するのを抑制するとともに、脆性き裂の伝播停止（アレスト）を達成することを目的として、耐脆性破壊特性に優れたＴＭＣＰ鋼板（Ｔｈｅｒｍｏ　Ｍｅｃｈａｎｉｃａｌ　Ｃｏｎｔｒｏｌ　Ｐｒｏｃｅｓｓ：熱加工制御）が提案されている。上記ＴＭＣＰ鋼板を用いることにより、脆性破壊発生に対する抵抗値である破壊靭性値が向上するため、通常の使用環境では、構造物が脆性破壊する可能性は極めて低くなる。しかしながら、地震や構造物同士の衝突の事故や災害等の際に、万が一、脆性破壊が生じると、脆性き裂がＨＡＺを伝播して大きな破壊が生じるおそれがある。 For this reason, TMCP steel sheet (Thermo Mechanical Control Process: excellent in brittle fracture resistance characteristics) for the purpose of suppressing the occurrence of brittle cracks in welded joints and achieving the propagation stop (arrest) of brittle cracks. Thermal processing control) has been proposed. By using the TMCP steel sheet, the fracture toughness value, which is a resistance value against the occurrence of brittle fracture, is improved, so that the possibility of the structure undergoing brittle fracture becomes extremely low in a normal use environment. However, if a brittle fracture occurs in the event of an earthquake, a collision between structures, a disaster, or the like, a brittle crack may propagate through the HAZ and cause a large fracture.
　例えば、コンテナ船等に代表される溶接構造体では、板厚５０ｍｍ程度のＴＭＣＰ鋼板等が使用され、万が一、溶接継手で脆性き裂が発生しても、溶接残留応力によって脆性き裂が溶接部から母材側に逸れるので、母材のアレスト性能を確保すれば、脆性き裂を母材で停止できると考えられていた。また、６０００ＴＥＵを超える大型コンテナ船等、さらに大型の溶接構造体においては、より大きな板厚の鋼板が必要となり、さらに、構造を簡素化するうえで鋼板の厚肉化が有効であることから、設計応力が高い高張力鋼の厚鋼板を用いることが求められていた。しかしながら、このような厚鋼板を用いた場合、ＨＡＺの破壊靭性の程度によっては、脆性き裂が母材に逸れること無くＨＡＺに沿って伝播し続け、溶接構造物に大きな破壊をもたらすおそれがある。 For example, in welded structures such as container ships, TMCP steel plates with a thickness of about 50 mm are used, and even if a brittle crack occurs in a welded joint, the brittle crack will be Therefore, it was thought that a brittle crack could be stopped at the base material if the arrest performance of the base material was ensured. In addition, in a large-sized welded structure such as a large container ship exceeding 6000 TEU, a steel plate having a larger thickness is required, and further, in order to simplify the structure, it is effective to increase the thickness of the steel plate. It has been required to use a high-strength steel plate having a high design stress. However, when such a thick steel plate is used, depending on the degree of fracture toughness of the HAZ, a brittle crack may continue to propagate along the HAZ without escaping to the base material, and there is a possibility of causing a large fracture in the welded structure. .
　上記問題を解決するため、突合せ溶接継手の一部に補修溶接（継手の一部分に対してはつりを行い、その箇所に埋め戻し溶接する）を施し、ＨＡＺに沿って伝播する脆性き裂を母材側に逸らせる構成とされた溶接構造体が提案されている（例えば、特許文献１）。
　しかしながら、特許文献１の溶接構造体では、母材の破壊靭性が非常に優れている場合には有効であるが、母材の破壊靭性が不充分な場合には、母材側に逸れた脆性き裂が長く伝播し、構造物としての強度が著しく低下するおそれがある。また、埋め戻し溶接部のボリュームが大きめとなり、工程時間が長くなるとともに、製造コストも増大するという問題がある。 In order to solve the above problems, repair welding is performed on a part of the butt welded joint (hanging is performed on a part of the joint and backfill welding is performed on the part), and a brittle crack propagating along the HAZ is formed on the base material. There has been proposed a welded structure configured to be deflected to the side (for example, Patent Document 1).
However, in the welded structure of Patent Document 1, it is effective when the fracture toughness of the base material is very excellent, but when the fracture toughness of the base material is insufficient, the brittleness deviated toward the base material side. There is a possibility that the crack propagates for a long time and the strength as a structure is remarkably lowered. In addition, there is a problem that the volume of the backfill weld is increased, the process time is increased, and the manufacturing cost is increased.
　また、溶接継手に発生する脆性き裂の伝播を停止させたい領域に、脆性き裂の伝播を制御する目的で、板状のアレスタ材が溶接線と交差するように貫通して溶接され、アレスタ材として、表面や裏面の板厚比２％以上の厚みの表層域における集合組織が適正化されたものを用いる溶接構造体が提案されている（例えば、特許文献２）。
　しかしながら、特許文献２に記載の溶接構造体を大型建造物に適用した場合、例えば、溶接継手を伝播した脆性き裂が、アレスタ材を鋼板に溶接する溶接継手を伝播してアレスタ材に突入し、そのままアレスタ材の内部を伝播した後、再び溶接継手を伝播するおそれがある。一方、溶接継手を伝播した脆性き裂が、アレスタ材及び該アレスタ材を鋼板に溶接する溶接継手の位置で母材側に逸れた場合には、上記同様、母材の破壊靭性が不充分だと脆性き裂が長く伝播し、溶接構造物としての強度が著しく低下するという問題も懸念される。 In addition, in order to control the propagation of brittle cracks in a region where it is desired to stop the propagation of brittle cracks generated in welded joints, a plate-like arrester material is welded so as to intersect the weld line. As a material, there has been proposed a welded structure using a material having an optimized texture in a surface layer region having a thickness of 2% or more on the front and back surfaces (for example, Patent Document 2).
However, when the welded structure described in Patent Document 2 is applied to a large building, for example, a brittle crack that has propagated through a welded joint propagates through a welded joint that welds the arrester material to a steel sheet and enters the arrester material. Then, after propagating through the inside of the arrester material as it is, there is a possibility of propagating through the welded joint again. On the other hand, if the brittle crack that propagated through the welded joint deviates to the base metal side at the position of the arrester material and the weld joint where the arrester material is welded to the steel plate, the fracture toughness of the base material is insufficient as described above. There is also a concern that the brittle crack propagates for a long time and the strength as a welded structure is significantly reduced.
特開２００５−１３１７０８号公報JP 2005-131708 A 特開２００７−０９８４４１号公報JP 2007-098441 A
　本発明は上記問題に鑑みてなされたものであり、たとえ溶接継手に脆性き裂が発生した場合であっても、脆性き裂が溶接継手や母材を伝播するのが抑制でき、溶接構造体の破断を防止することが可能な、耐脆性き裂伝播性に優れた溶接構造体を提供することを目的とする。 The present invention has been made in view of the above problems, and even when a brittle crack occurs in a welded joint, it is possible to suppress the brittle crack from propagating through the welded joint or the base material, and a welded structure. An object of the present invention is to provide a welded structure excellent in brittle crack propagation resistance that can prevent fracture of the steel.
　本発明者らは、溶接構造体の溶接継手に発生した脆性き裂が、溶接継手や母材を伝播するのを防止するため、溶接継手の途中に、特許文献２のような脆性き裂の伝播を制御する継手構造を設ける場合について鋭意研究した。
　この結果、脆性き裂の伝播を制御する継手構造の形状並びに鋼材特性を適正化することにより、溶接継手及び母材における脆性き裂の伝播を抑制し、溶接構造体に大規模な破壊が発生するのを防止できることを見出し、本発明を完成した。
　即ち、本発明の要旨は、請求の範囲に記載した以下の内容に関する。 In order to prevent the brittle crack generated in the welded joint of the welded structure from propagating through the welded joint or the base material, the inventors have introduced a brittle crack as in Patent Document 2 in the middle of the welded joint. We have intensively studied the case of providing a joint structure that controls propagation.
As a result, by optimizing the shape of the joint structure that controls the propagation of brittle cracks and the steel material properties, the propagation of brittle cracks in welded joints and base metal is suppressed, and large-scale fracture occurs in the welded structure. As a result, the present invention has been completed.
That is, the gist of the present invention relates to the following contents described in the claims.
　［１］　少なくとも一部の領域の脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上である鋼板を、互いに突合せ溶接することで形成されてなる鋼板溶接継手において、
　前記鋼板溶接継手の少なくとも一箇所に、鋼板溶接継手に発生した脆性き裂の伝播を制御する耐脆性き裂伝播方向制御部が設けられており、
　該耐脆性き裂伝播方向制御部は、一方の鋼板に形成された突起部と、それに対向する他方の鋼板との間で突合せ溶接されて形成された傾斜ビードを有しており、
　該傾斜ビードは、前記鋼板溶接継手の溶接線上からその長手方向に延伸するとともに、鋼板溶接継手の長手方向に対して１５°以上５０°以下の範囲の角度で傾斜しており、かつ、傾斜ビードの後端部は、少なくとも、前記鋼板のＫｃａが４０００Ｎ／ｍｍ１．５以上である領域に向かい合うように形成されていること、を特徴とする耐脆性き裂伝播性に優れた鋼板溶接継手。 [1] In the steel plate welded joint formed by butt welding the steel plates having a brittle crack propagation stop characteristic Kca of at least a part of the region of 4000 N / mm 1.5 or more,
At least one location of the steel plate welded joint is provided with a brittle crack propagation direction control unit that controls the propagation of a brittle crack generated in the steel plate welded joint,
The brittle crack propagation direction control part has an inclined bead formed by butt welding between a protrusion formed on one steel plate and the other steel plate facing it,
The inclined bead extends in the longitudinal direction from the weld line of the steel plate welded joint, and is inclined at an angle in the range of 15 ° to 50 ° with respect to the longitudinal direction of the steel plate welded joint. A steel plate welded joint excellent in brittle crack propagation resistance, characterized in that the rear end portion is formed so as to face at least a region where Kca of the steel plate is 4000 N / mm 1.5 or more.
　［２］　前記耐脆性き裂伝播方向制御部に備えられる前記傾斜ビードは、前記鋼板溶接継手の長手方向に沿った高さＨ（ｍｍ）、鋼板溶接継手の長手方向と交差する方向における横幅Ｗ（ｍｍ）の各々の寸法が、下記（１）、（２）式で表される関係を満足すること、を特徴とする上記［１］に記載の耐脆性き裂伝播性に優れた鋼板溶接継手。
　２Ｔ　≦　Ｈ　　　　・・・・・　（１）
　ｄ＋５０　≦　Ｗ　　・・・・・　（２）
　但し、上記（１）、（２）式中において、Ｔは前記鋼板の板厚（ｍｍ）を表し、ｄは前記鋼板溶接継手における溶接金属部の幅（ｍｍ）を表す。
　［３］　前記鋼板の板厚が２５ｍｍ以上１５０ｍｍ以下であること、を特徴とする上記
［１］又は［２］に記載の耐脆性き裂伝播性に優れた鋼板溶接継手。
　［４］　前記鋼板は、少なくとも一部の領域の脆性き裂伝播停止特性Ｋｃａが６０００Ｎ／ｍｍ１．５以上であり、前記傾斜ビードの後端部は、少なくとも、前記鋼板のＫｃａが６０００Ｎ／ｍｍ１．５以上である領域に向かい合うように形成されていること、を特徴とする上記［１］~［３］の何れかに記載の耐脆性き裂伝播性に優れた鋼板溶接継手。 [2] The inclined beads provided in the brittle crack propagation direction control unit have a height H (mm) along the longitudinal direction of the steel plate welded joint and a lateral width W in a direction intersecting the longitudinal direction of the steel plate welded joint. (Mm) Each dimension of (mm) satisfies the relationship expressed by the following formulas (1) and (2), and the steel plate welding having excellent brittle crack propagation resistance according to the above [1] Fittings.
2T ≤ H (1)
d + 50 ≦ W (2)
However, in said Formula (1) and (2), T represents the plate | board thickness (mm) of the said steel plate, and d represents the width | variety (mm) of the weld metal part in the said steel plate welded joint.
[3] The steel plate welded joint having excellent brittle crack propagation properties according to the above [1] or [2], wherein the steel plate has a thickness of 25 mm or more and 150 mm or less.
[4] The steel plate has a brittle crack propagation stop characteristic Kca of at least a partial region of 6000 N / mm 1.5 or more, and the rear end of the inclined bead has at least a Kca of the steel plate of 6000 N / mm. The steel plate welded joint having excellent brittle crack propagation resistance according to any one of the above [1] to [3], wherein the steel plate is formed so as to face a region of 1.5 or more.
　［５］　前記鋼板は、前記鋼板溶接継手の長手方向で配列される少なくとも２以上の小鋼板からなるとともに、該小鋼板を互いに突合せ溶接することで小鋼板溶接継手が形成されており、前記小鋼板溶接継手は、前記鋼板溶接継手の溶接線上から延在する前記耐脆性き裂伝播方向制御部の、前記傾斜ビードの後端側に形成される水平ビードを含むこと、を特徴とする上記［１］~［４］の何れかに記載の耐脆性き裂伝播性に優れた鋼板溶接継手。 [5] The steel plate is made of at least two or more small steel plates arranged in the longitudinal direction of the steel plate welded joint, and a small steel plate welded joint is formed by butt welding the small steel plates to each other. The steel plate welded joint includes a horizontal bead formed on a rear end side of the inclined bead of the brittle crack propagation direction control unit extending from a weld line of the steel plate welded joint. [1] to [4] A steel plate welded joint excellent in brittle crack propagation resistance.
　［６］　母材の少なくとも一部の脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上である鋼板同士を突合せ溶接することで鋼板溶接継手が形成されてなる溶接構造体であって、該鋼板溶接継手の少なくとも１箇所に、上記［１］~［５］の何れかに記載の耐脆性き裂伝播方向制御部が設けられていること、を特徴とする耐脆性き裂伝播性に優れた溶接構造体。 [6] A welded structure in which a steel plate welded joint is formed by butt welding two or more steel plates having a brittle crack propagation stop characteristic Kca of 4000 N / mm 1.5 or more of a base material, The brittle crack propagation property is characterized in that the brittle crack propagation direction control section according to any one of the above [1] to [5] is provided in at least one place of the steel plate welded joint. Excellent welded structure.
　なお、本発明では、溶接金属部と溶接熱影響部を含む部分を溶接継手と定義する。また、脆性き裂伝播停止特性Ｋｃａは、当該溶接構造体が使用される温度、あるいは設計温度における数値である。 In the present invention, a portion including a weld metal portion and a weld heat affected zone is defined as a weld joint. The brittle crack propagation stop characteristic Kca is a numerical value at the temperature at which the welded structure is used or at the design temperature.
　本発明の溶接構造体によれば、鋼板を突合せ溶接して形成した溶接継手の少なくとも一箇所に、一方の鋼板に形成された突起部と、それに対向する他方の鋼板との間で突合せ溶接されて形成された傾斜ビードとからなる耐脆性き裂伝播方向制御部が設けられているので、たとえ溶接継手に脆性き裂が発生した場合であっても、溶接継手を伝播する脆性き裂を、耐脆性き裂伝播方向制御部によって鋼板母材のアレスト性能の高い部位にそらしたり、あるいは該耐脆性き裂伝播方向制御部で阻止することができ、脆性き裂が溶接継手や母材を伝播するのが抑制できる。
　従って、大規模な破壊が発生するのを未然防止することが可能な溶接構造体を、高い生産効率及び低コストで得ることができる。
　このような本発明に係る溶接構造体が、大型船舶をはじめ、建築構造物や土木鋼構造物等の各種溶接構造物に使用されることで、溶接構造物の大型化、破壊に対する高い安全性、建造における溶接の高能率化、鋼材の経済性等々が同時に満たされことから、その産業上の効果は計り知れない。 According to the welded structure of the present invention, at least one portion of a welded joint formed by butt-welding steel plates is butt-welded between a protrusion formed on one steel plate and the other steel plate facing it. Because the brittle crack propagation direction control part consisting of the inclined beads formed in this way is provided, even if a brittle crack occurs in the welded joint, the brittle crack propagating through the welded joint The brittle crack propagation direction control part can deflect the steel plate base metal to a part with high arrest performance, or the brittle crack propagation direction control part can prevent the brittle crack from propagating through the welded joint or the base material. Can be suppressed.
Therefore, it is possible to obtain a welded structure capable of preventing the occurrence of large-scale destruction with high production efficiency and low cost.
Such a welded structure according to the present invention is used for various types of welded structures such as large ships, building structures, civil engineering steel structures, etc., so that the welded structures can be increased in size and destroyed with high safety. Since the efficiency of welding in construction, the economics of steel materials, etc. are satisfied at the same time, the industrial effects are immeasurable.
　図１は、本発明を説明する図であり、鋼板同士が溶接されて形成された鋼板溶接継手の一部に、傾斜ビードを有する耐脆性き裂伝播方向制御部が設けられた状態を示す平面図である。
　図２は、鋼板溶接継手の一部に図１に示される耐脆性き裂伝播方向制御部が設けられた場合の脆性き裂の進展状況を説明する模式図である。
　図３は、本発明に係る鋼板溶接継手及び溶接構造体のき裂伝播特性を説明する模式図であり、図１に示す鋼板溶接継手及び溶接構造体の要部拡大図である。
　図４は、本発明に係る鋼板溶接継手及び溶接構造体を、船舶用溶接構造体に適用した場合について説明する概略図である。
　図５は、本発明に係る鋼板溶接継手及び溶接構造体の他の例を説明する図３と同様の図である。
　図６は、本発明に係る鋼板溶接継手及び溶接構造体の他の例を説明する図３と同様の図である。
　図７は、本発明に係る鋼板溶接継手及び溶接構造体の他の例を説明する図３と同様の図である。
　図８は、本発明の実施例で用いる溶接継手試験体について説明する図である。
　図９は、本発明の実施例における耐脆性き裂伝播性を評価するための引張試験方法について説明する図である。 FIG. 1 is a diagram illustrating the present invention, and is a plane showing a state in which a brittle crack propagation direction control unit having an inclined bead is provided in a part of a steel plate welded joint formed by welding steel plates together. FIG.
FIG. 2 is a schematic diagram for explaining the progress of a brittle crack when a brittle crack propagation direction control unit shown in FIG. 1 is provided in a part of a steel plate welded joint.
FIG. 3 is a schematic diagram for explaining the crack propagation characteristics of the steel plate welded joint and welded structure according to the present invention, and is an enlarged view of the main part of the steel plate welded joint and welded structure shown in FIG.
FIG. 4 is a schematic diagram illustrating a case where the steel plate welded joint and the welded structure according to the present invention are applied to a marine welded structure.
FIG. 5 is a view similar to FIG. 3 for explaining another example of the steel plate welded joint and welded structure according to the present invention.
FIG. 6 is a view similar to FIG. 3 for explaining another example of the steel plate welded joint and welded structure according to the present invention.
FIG. 7 is a view similar to FIG. 3 for explaining another example of the steel plate welded joint and welded structure according to the present invention.
FIG. 8 is a diagram for explaining a welded joint specimen used in an example of the present invention.
FIG. 9 is a diagram illustrating a tensile test method for evaluating the brittle crack propagation property in an example of the present invention.
　以下、本発明の耐脆性き裂伝播性に優れた溶接構造体の実施の形態について図面を参照しながら詳細に説明する。なお、本実施形態は、発明の趣旨をより良く理解させるために詳細に説明するものであるから、特に指定の無い限り、本発明を限定するものではない。 Hereinafter, embodiments of a welded structure excellent in brittle crack propagation resistance of the present invention will be described in detail with reference to the drawings. In addition, since this embodiment is described in detail for better understanding of the gist of the invention, the present invention is not limited unless otherwise specified.
　従来、鋼板溶接継手において発生した脆性き裂は、主として、鋼板溶接継手に沿って長手方向を伝播する。このため、鋼板溶接継手に生じた脆性き裂が起点となり、溶接構造体全体に大きな破壊が生じるおそれがあるという問題があった。
　本発明者等は、上述のような脆性き裂の伝播方向を効果的に制御し、溶接構造体においてき裂が伝播するのを抑制するためには、上記従来技術において、さらに脆性き裂の伝播を制御する部材の形状並びに鋼材特性を適正化することが重要であることを知見した。
　本発明の基本原理について図１、２を用いて説明する。 Conventionally, a brittle crack generated in a steel plate welded joint mainly propagates in the longitudinal direction along the steel plate welded joint. For this reason, the brittle crack which arose in the steel plate welded joint becomes a starting point, and there existed a problem that there existed a possibility that a big fracture might arise in the whole welded structure.
In order to effectively control the propagation direction of the brittle crack as described above and suppress the propagation of the crack in the welded structure, the present inventors have further improved the brittle crack. It was found that it is important to optimize the shape of the member that controls propagation and the steel material characteristics.
The basic principle of the present invention will be described with reference to FIGS.
　本発明では、鋼板２、２を突合せ溶接して形成された鋼板溶接継手１の途中に、鋼板溶接継手に発生した脆性き裂の伝播を制御する耐脆性き裂伝播方向制御部３を設ける。
　該耐脆性き裂伝播方向制御部３は、突合せ溶接された一方の鋼板に突出部４を設け、他方の鋼板に突出部４に対応する形状の切欠き部５を設け、両者を突合せ溶接することで形成される。
　突起部４は、鋼板端部から傾斜して突出しており、突起部４と切欠き部５の間の溶接部には、鋼板内部に向かって傾斜して延伸する傾斜ビード３１が、前記鋼板溶接継手１から連続して形成される。 In the present invention, a brittle crack propagation direction control unit 3 for controlling the propagation of a brittle crack generated in the steel plate welded joint is provided in the middle of the steel plate welded joint 1 formed by butt welding the steel plates 2 and 2.
The brittle crack propagation direction control unit 3 is provided with a protruding portion 4 on one steel plate butt welded, a notch portion 5 having a shape corresponding to the protruding portion 4 on the other steel plate, and butt-welding the two. Is formed.
The protruding portion 4 is inclined and protrudes from the end of the steel plate, and an inclined bead 31 that extends toward the inside of the steel plate is provided at the welded portion between the protruding portion 4 and the notch portion 5. It is formed continuously from the joint 1.
　鋼板溶接継手が大きな破壊エネルギーを受けて鋼板溶接継手１に脆性き裂が発生した場合でも、この耐脆性き裂伝播方向制御部３を設けることで、き裂の伝播を次のようにして制御する。
　鋼板溶接継手１の長手方向の一方側（図２−ａ~ｅ上側）で発生した脆性き裂ＣＲは、鋼板２と鋼板溶接継手１の境界に沿って伝播する。き裂ＣＲが傾斜ビード３１に達したとき、き裂ＣＲは、突起部４に突入することなく、図２−ａに示すように、鋼板２と傾斜ビード３１の境界に沿って伝播し、鋼板２の母材部に到達することになる。このとき、母材部に進入しても鋼板２の脆性き裂伝播停止特性Ｋｃａが高いと、そこでき裂ＣＲの進展を停止することができる。 Even when a steel plate welded joint receives a large fracture energy and a brittle crack occurs in the steel plate welded joint 1, by providing the brittle crack propagation direction control unit 3, the propagation of the crack is controlled as follows. To do.
The brittle crack CR generated on one side in the longitudinal direction of the steel plate welded joint 1 (upper side in FIGS. 2A to 2E) propagates along the boundary between the steel plate 2 and the steel plate welded joint 1. When the crack CR reaches the inclined bead 31, the crack CR propagates along the boundary between the steel plate 2 and the inclined bead 31 as shown in FIG. The base material part of 2 is reached. At this time, if the brittle crack propagation stop characteristic Kca of the steel plate 2 is high even if it enters the base metal part, the progress of the crack CR can be stopped there.
　また、破壊エネルギーの程度によっては、き裂が傾斜ビードから突起部４に突入する場合もある。その場合でも、突起の高さが十分ある場合や、突起を形成する母材の脆性き裂伝播停止特性Ｋｃａが十分に高い場合には、図２−ｂに示すよう、に突起部４の領域の内部で脆性き裂の伝播を停止させることができる。
　さらに、鋼板溶接継手１の長手方向の他方側（下側）から脆性き裂ＣＲが伝播してきた場合でも、耐脆性き裂伝播方向制御部３のＫｃａを高くし、かつ耐脆性き裂伝播方向制御部３の溶接継手に沿った方向の高さを十分なものにしておけば、図２−ｆに示すように、耐脆性き裂伝播方向制御部３内部で、き裂ＣＲの進展を停止することができる。 Further, depending on the degree of fracture energy, a crack may enter the protrusion 4 from the inclined bead. Even in such a case, when the height of the protrusion is sufficient, or when the brittle crack propagation stop characteristic Kca of the base material forming the protrusion is sufficiently high, as shown in FIG. The propagation of brittle cracks can be stopped inside.
Furthermore, even when the brittle crack CR propagates from the other side (lower side) of the longitudinal direction of the steel plate welded joint 1, the Kca of the brittle crack propagation direction control unit 3 is increased and the brittle crack propagation direction. If the height in the direction along the welded joint of the control unit 3 is sufficient, as shown in FIG. 2-f, the progress of the crack CR is stopped inside the brittle crack propagation direction control unit 3. can do.
　逆に、耐脆性き裂伝播方向制御部３のＫｃａが低い場合や耐脆性き裂伝播方向制御部３の形状が十分でない場合などでは、図２−ｃのように、脆性き裂ＣＲが耐脆性き裂伝播方向制御部３を貫通したり、図２−ｄのように傾斜ビードから鋼板溶接継手に戻り、再び鋼板溶接継手１を伝播することが想定される。また、鋼板のＫｃａが低い場合には、傾斜ビードから鋼板に逸れた脆性き裂が図２−ｅのように鋼板を伝播することも想定される。 On the contrary, when the Kca of the brittle crack propagation direction control unit 3 is low or when the shape of the brittle crack propagation direction control unit 3 is not sufficient, the brittle crack CR is resistant as shown in FIG. It is assumed that the brittle crack propagation direction control unit 3 is penetrated, or the inclined bead is returned to the steel plate welded joint as shown in FIG. Further, when the Kca of the steel plate is low, it is also assumed that a brittle crack deviating from the inclined bead to the steel plate propagates through the steel plate as shown in FIG.
　本発明は、このような基本原理の下で、脆性き裂の進展を阻止する母材鋼板の条件、脆性き裂の進展を制御する耐脆性き裂伝播方向制御部の条件などについてさらに検討してなされたものであり、以下、本発明の実施形態について詳細に説明する。 Under such basic principles, the present invention further examines the conditions of the base steel plate that inhibits the development of brittle cracks, the conditions of the brittle crack propagation direction control unit that controls the development of brittle cracks, and the like. Hereinafter, embodiments of the present invention will be described in detail.
［第１の実施形態］
＜全体の構成＞
　第１の実施形態は、図３に示すように、母材の脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上である鋼板２、２を突合せ溶接することで鋼板溶接継手１が形成されている場合の例であり、以下、この継手に適用した形態を溶接構造体Ａと称して説明する。
　溶接構造体Ａにおいては、鋼板溶接継手１の少なくとも一箇所に、鋼板溶接継手に発生した脆性き裂の伝播を、鋼板母材側にそらすため耐脆性き裂伝播方向制御部３が設けられる。耐脆性き裂伝播方向制御部３が設けられる位置は、衝突や地震などによる大きな破壊エネルギーにさらされたときに、き裂の発生・伝播が予測される鋼板溶接継手の途中が望ましい。
　該耐脆性き裂伝播方向制御部３は、突合せ溶接された一方の鋼板に突出部４を設け、他方の鋼板に突出部４に対応する形状の切欠き部５を設け、両者を突合せ溶接することで、鋼板継手１１と１２の間に形成される。
　突起部４は、鋼板端部から傾斜して突出しており、突起部４と切欠き部５の間の溶接部には、鋼板内部に向かって傾斜して延伸する傾斜ビード３１が、前記鋼板溶接継手１から連続して形成される。
　傾斜ビード３１は、鋼板溶接継手１の長手方向に対して１５°以上５０°以下の範囲の角度で傾斜するように形成されており、傾斜ビード３１の後端３１ｂに水平ビード３２の一端３２ａが接続され、水平ビード３２の他端３２ｂが鋼板継手１２に接続されている。 [First Embodiment]
<Overall configuration>
In the first embodiment, as shown in FIG. 3, a steel plate welded joint 1 is formed by butt welding steel plates 2 and 2 having a brittle crack propagation stop characteristic Kca of the base material of 4000 N / mm 1.5 or more. In the following, a form applied to this joint will be referred to as a welded structure A and described below.
In the welded structure A, a brittle crack propagation direction control unit 3 is provided in at least one location of the steel plate weld joint 1 in order to divert the propagation of the brittle crack generated in the steel plate weld joint toward the steel plate base material side. The position where the brittle crack propagation direction control unit 3 is provided is preferably in the middle of a steel plate welded joint where crack generation / propagation is predicted when exposed to large fracture energy due to collision or earthquake.
The brittle crack propagation direction control unit 3 is provided with a protruding portion 4 on one steel plate butt welded, a notch portion 5 having a shape corresponding to the protruding portion 4 on the other steel plate, and butt-welding the two. Thus, it is formed between the steel plate joints 11 and 12.
The protruding portion 4 is inclined and protrudes from the end of the steel plate, and an inclined bead 31 that extends toward the inside of the steel plate is provided at the welded portion between the protruding portion 4 and the notch portion 5. It is formed continuously from the joint 1.
The inclined bead 31 is formed to be inclined at an angle in the range of 15 ° to 50 ° with respect to the longitudinal direction of the steel plate welded joint 1, and one end 32 a of the horizontal bead 32 is provided at the rear end 31 b of the inclined bead 31. The other end 32 b of the horizontal bead 32 is connected to the steel plate joint 12.
＜鋼板＞
　鋼板２は、脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上とされる鋼材からなる。耐脆性き裂伝播性がより向上する点からは、６０００Ｎ／ｍｍ１．５以上であることが好ましい。
　鋼板２は、上記Ｋｃａを満足しておれば、化学成分組成や金属組織等については、特定のものに制限されず、船舶用溶接構造体、建築構造物及び土木鋼構造物等の分野において、従来公知の鋼板特性を備えるものを使用することができる。
　例えば、質量％で、Ｃ：０．０１~０．１８％、Ｓｉ：０．０１~０．５％、Ｍｎ：０．３~２．５％、Ｐ：０．０１％以下、Ｓ：０．００１~０．０２％を含有する組成を基本とし、この組成に、求められる性能に応じて、さらに、Ｎ：０．００１~０．００８％、Ｂ：０．０００１~０．００５％、Ｍｏ：０．０１~１．０％、Ａｌ：０．００２~０．１％、Ｔｉ：０．００３~０．０５％、Ｃａ：０．０００１~０．００３％、Ｍｇ：０．００１~０．００５％、Ｖ：０．００１~０．１８％、Ｎｉ：０．０１~５．５％、Ｎｂ：０．００５~０．０５％、Ｃｕ：０．０１~３．０％、Ｃｒ：０．０１~１．０％、ＲＥＭ：：０．０００５~０．００５％の１種または２種以上を含有させ、残部はＦｅ及び不可避不純物によって構成される鋼があげられる。
　特に、脆性き裂伝播停止特性Ｋｃａが６０００Ｎ／ｍｍ１．５以上の鋼板としては、特開２００７−３０２９９３号公報や、特開２００８−２４８３８２号公報などに示されるような組成の厚鋼板が好適に使用できる。 <Steel plate>
The steel plate 2 is made of a steel material having a brittle crack propagation stop characteristic Kca of 4000 N / mm 1.5 or more. From the viewpoint of further improving the brittle crack propagation resistance, it is preferably 6000 N / mm 1.5 or more.
As long as the steel plate 2 satisfies the above Kca, the chemical composition, metal structure, and the like are not limited to specific ones, and in the fields of marine welded structures, building structures, civil engineering steel structures, etc. What has a conventionally well-known steel plate characteristic can be used.
For example, in mass%, C: 0.01 to 0.18%, Si: 0.01 to 0.5%, Mn: 0.3 to 2.5%, P: 0.01% or less, S: 0 Based on a composition containing 0.001 to 0.02%, N: 0.001 to 0.008%, B: 0.0001 to 0.005%, depending on the required performance. Mo: 0.01 to 1.0%, Al: 0.002 to 0.1%, Ti: 0.003 to 0.05%, Ca: 0.0001 to 0.003%, Mg: 0.001 to 0.005%, V: 0.001 to 0.18%, Ni: 0.01 to 5.5%, Nb: 0.005 to 0.05%, Cu: 0.01 to 3.0%, Cr One or two or more of: 0.01 to 1.0%, REM :: 0.0005 to 0.005%, with the balance being steel composed of Fe and inevitable impurities.
In particular, as a steel plate having a brittle crack propagation stopping property Kca of 6000 N / mm 1.5 or more, a thick steel plate having a composition as shown in JP 2007-302993 A or JP 2008-248382 A is suitable. Can be used for
　鋼板２の板厚は、２５ｍｍ以上１５０ｍｍ以下の範囲とすることが好ましい。鋼板２の板厚がこの範囲であれば、溶接構造体としての鋼板強度を確保することができるとともに、優れた耐脆性き裂伝播性を得ることが可能となる。特に、４０ｍｍ以上の鋼板を用いた溶接構造体では、脆性き裂の伝播を止めるための有効な手段がなく、板厚４０ｍｍ以上、より好ましくは５０ｍｍ以上で、１００ｍｍ以下の鋼板を用いた溶接構造体において、本発明はより効果的に実施される。 The plate thickness of the steel plate 2 is preferably in the range of 25 mm to 150 mm. When the plate thickness of the steel plate 2 is within this range, it is possible to ensure the strength of the steel plate as a welded structure and to obtain excellent brittle crack propagation resistance. In particular, in a welded structure using a steel plate of 40 mm or more, there is no effective means for stopping the propagation of a brittle crack, and a welded structure using a steel plate having a plate thickness of 40 mm or more, more preferably 50 mm or more and 100 mm or less. In the body, the present invention is more effectively implemented.
＜耐脆性き裂伝播方向制御部＞
　耐脆性き裂伝播方向制御部３は、鋼板溶接継手１の少なくとも一部に設けられる溶接継手からなるものであり、図３に示す例では、鋼板溶接継手１をなす２箇所の鋼板継手１１、１２の間に耐脆性き裂伝播方向制御部３が設けられている。
　耐脆性き裂伝播方向制御部３は、鋼板溶接継手１（図示例では鋼板継手１１）の溶接線Ｌ上から延伸するとともに、鋼板溶接継手１の長手方向に対して１５°以上５０°以下の範囲の傾斜角度θで傾斜する傾斜ビード３１を具備してなる。また、図示例の耐脆性き裂伝播方向制御部３は、傾斜ビード３１の後端３１ｂに水平ビード３２の一端３２ａが接続され、水平ビード３２の他端３２ｂが鋼板継手１２に接続されている。
　本発明に係る鋼板溶接継手並びにそれが用いられてなる溶接構造体は、上述したような耐脆性き裂伝播方向制御部３を備えることにより、仮に、鋼板溶接継手１に脆性き裂が生じた場合でも、この脆性き裂の伝播方向を制御し、鋼板溶接継手１を貫くようにき裂が伝播して互いに溶接された鋼板２同士が分断するのを防止するものである。 <Brittle crack propagation direction control unit>
The brittle crack propagation direction control unit 3 is formed of a welded joint provided on at least a part of the steel plate welded joint 1. In the example shown in FIG. 3, two steel plate joints 11 forming the steel plate welded joint 1, Between 12, a brittle crack propagation direction control unit 3 is provided.
The brittle crack propagation direction control unit 3 extends from the weld line L of the steel plate welded joint 1 (steel plate joint 11 in the illustrated example) and is 15 ° or more and 50 ° or less with respect to the longitudinal direction of the steel plate welded joint 1. An inclined bead 31 inclined at an inclination angle θ in the range is provided. Further, in the illustrated example of the brittle crack propagation direction control unit 3, one end 32 a of the horizontal bead 32 is connected to the rear end 31 b of the inclined bead 31, and the other end 32 b of the horizontal bead 32 is connected to the steel plate joint 12. .
The steel plate welded joint according to the present invention and the welded structure in which the steel plate welded joint is used include a brittle crack propagation direction control unit 3 as described above, so that a brittle crack is temporarily generated in the steel plate welded joint 1. Even in this case, the propagation direction of the brittle crack is controlled to prevent the crack from propagating through the welded joint 1 to separate the steel plates 2 welded to each other.
　耐脆性き裂伝播方向制御部３は、上述のように、鋼板溶接継手１１の溶接線Ｌ上に配された頂部３１ａから延在する傾斜ビード３１が、鋼板溶接継手１（１１、１２）の長手方向に対して１５°以上５０°以下の範囲の角度θで傾斜していることが好ましい。
　傾斜ビード３１の傾斜角度を上記範囲とすることにより、鋼板溶接継手１１を伝播する脆性き裂が生じた場合でも、このき裂を、鋼板溶接継手から傾斜ビード３１に沿って進展するように導き、鋼板１の母材側に安定的に逸らすことが可能となる。 As described above, in the brittle crack propagation direction control unit 3, the inclined bead 31 extending from the top portion 31a disposed on the weld line L of the steel plate welded joint 11 is formed on the steel plate welded joint 1 (11, 12). It is preferable to incline at an angle θ in the range of 15 ° to 50 ° with respect to the longitudinal direction.
By setting the inclination angle of the inclined bead 31 within the above range, even when a brittle crack propagating through the steel plate welded joint 11 is generated, the crack is guided to propagate along the inclined bead 31 from the steel plate welded joint. The steel plate 1 can be deflected stably toward the base material side.
　耐脆性き裂伝播方向制御部の傾斜ビードの角度θが１５°未満だと、傾斜ビードに沿ってき裂を伝播させても、この傾斜ビードを通過したき裂の位置が、もとのき裂伝播経路である鋼板溶接継手の位置と近くなるため、き裂が再び鋼板溶接継手に突入して伝播するおそれがある。
　また、傾斜ビードの角度θが５０°を超えると、鋼板溶接継手を伝播した脆性き裂が傾斜ビード３１に沿って伝播した後に、鋼板の母材側に逸れず、そのまま、突起部４内に突入する可能性が大きくなる。この場合、耐脆性き裂伝播方向制御部に対して直接的に脆性き裂が突入するため、突起部４の脆性き裂伝播停止特性Ｋｃａが十分でない場合には、き裂の伝播が停止せずに耐脆性き裂伝播方向制御部を通過し、再び鋼板溶接継手に突入して伝播するおそれがある。
　また、脆性き裂伝播方向制御部の高さＨを、以下に説明するような範囲で確保しつつ、鋼板溶接継手の長手方向に対する耐脆性き裂伝播方向制御部の傾斜ビードの角度θが５０°を超えると、脆性き裂伝播方向制御部の幅Ｗが大きくなりすぎて現実的でない。
　脆性き裂が傾斜ビード３１に沿って伝播するように導くための傾斜角度θのより好ましい範囲は、２０°以上４５°以下であり、さらに好ましい範囲は２５°以上４０°以下である。 If the angle θ of the inclined bead of the brittle crack propagation direction control unit is less than 15 °, even if the crack propagates along the inclined bead, the position of the crack that has passed through the inclined bead Since it is close to the position of the steel plate welded joint, which is the propagation path, the crack may enter the steel plate welded joint again and propagate.
Further, when the angle θ of the inclined bead exceeds 50 °, after the brittle crack propagated through the steel plate welded joint propagates along the inclined bead 31, it does not escape to the base metal side of the steel plate, and remains in the protrusion 4 as it is. The possibility of rushing increases. In this case, since the brittle crack directly enters the brittle crack propagation direction control part, if the brittle crack propagation stop characteristic Kca of the projection 4 is not sufficient, the crack propagation is stopped. Without passing through the brittle crack propagation direction control unit, it may enter the steel plate welded joint and propagate again.
Further, the angle θ of the inclined bead of the brittle crack propagation direction control unit with respect to the longitudinal direction of the steel plate welded joint is 50 while securing the height H of the brittle crack propagation direction control unit in the range described below. If it exceeds 0 °, the width W of the brittle crack propagation direction control portion becomes too large, which is not realistic.
A more preferable range of the inclination angle θ for guiding the brittle crack to propagate along the inclined beads 31 is 20 ° or more and 45 ° or less, and a more preferable range is 25 ° or more and 40 ° or less.
　なお、傾斜ビード３１と鋼板継手１２とを結ぶ水平ビード３２は、水平ビード３２と鋼板継手１２の間の角度θ２（図１−ｂ参照）が、８０°（好ましくは９０°）以上、１１０°以下の範囲になるように形成してあればよい。この範囲を外れると、脆性き裂が、傾斜ビードの途中から突起部４に突入したり、図２−ｄのように鋼板継手に戻る危険性がある。 The horizontal bead 32 connecting the inclined bead 31 and the steel plate joint 12 has an angle θ2 (see FIG. 1-b) between the horizontal bead 32 and the steel plate joint 12 of 80 ° (preferably 90 °) or more and 110 °. What is necessary is just to form so that it may become the following ranges. If it is out of this range, there is a risk that the brittle crack may enter the protrusion 4 from the middle of the inclined bead or return to the steel plate joint as shown in FIG.
　本実施形態の鋼板溶接継手１（溶接構造体Ａ）に用いられる耐脆性き裂伝播方向制御部３に設けられる突起部４は、前記鋼板溶接継手の長手方向に沿った高さＨ（ｍｍ）、前記鋼板溶接継手１から突出する横幅Ｗ（ｍｍ）が、下記（１）、（２）式で表される関係を満足することが好ましい。
　２Ｔ　≦　Ｈ　　　　・・・・・　（１）
　ｄ＋５０　≦　Ｗ　　・・・・・　（２）
　但し、上記（１）、（２）式中において、Ｔ（ｍｍ）は前記鋼板の板厚を表し、ｄ（ｍｍ）は前記鋼板溶接継手における溶接金属部の幅を表す。 The protrusion 4 provided on the brittle crack propagation direction control unit 3 used in the steel plate welded joint 1 (welded structure A) of the present embodiment has a height H (mm) along the longitudinal direction of the steel plate welded joint. The lateral width W (mm) protruding from the steel plate welded joint 1 preferably satisfies the relationship represented by the following formulas (1) and (2).
2T ≤ H (1)
d + 50 ≦ W (2)
However, in said (1) and (2) type | formula, T (mm) represents the plate | board thickness of the said steel plate, and d (mm) represents the width | variety of the weld metal part in the said steel plate welded joint.
　耐脆性き裂伝播方向制御部３に設けられる傾斜ビード３１の各寸法値を上記関係とすることにより、仮に、脆性き裂が鋼板溶接継手１を伝播した場合であっても、き裂の伝播方向を、傾斜ビードによって鋼板２の母材側へ効果的に逸らすことが可能となる。また、き裂が突起部４内に突入した場合でも、突起部内部でき裂の進展を停止させることが可能となる。
　耐脆性き裂伝播方向制御部の各寸法値の関係が、上記（１）、（２）式で表される関係を満たさない場合、鋼板溶接継手に生じたき裂の状態によっては、このき裂が耐脆性き裂伝播方向制御部に進入し、鋼板の母材側に逸れずに鋼板溶接継手を伝播してしまう可能性がある。
　脆性き裂の伝播をより確実に止めるためには、上記高さＨは、２００ｍｍ以上、または２５０ｍｍ以上、さらには、３００ｍｍ以上がより好ましく、上記（１）式において、Ｈ／Ｔは、２．０以上が好ましく、３．０以上がより好ましい。 By setting the dimensional values of the inclined beads 31 provided in the brittle crack propagation direction control unit 3 as described above, even if the brittle crack propagates through the steel plate welded joint 1, the propagation of the crack The direction can be effectively diverted to the base material side of the steel plate 2 by the inclined beads. Further, even when a crack enters the protrusion 4, it is possible to stop the progress of the crack in the protrusion.
If the relationship between the dimensional values of the brittle crack propagation direction control part does not satisfy the relationship expressed by the above equations (1) and (2), depending on the state of the crack generated in the steel plate welded joint, May enter the brittle crack propagation direction control section and propagate through the steel plate welded joint without deviating to the base metal side of the steel plate.
In order to more reliably stop the propagation of the brittle crack, the height H is preferably 200 mm or more, or 250 mm or more, and more preferably 300 mm or more. In the above formula (1), H / T is 2. 0 or more is preferable and 3.0 or more is more preferable.
＜脆性き裂の伝播方向の制御＞
　上記構成とされた溶接構造体Ａにおいて、鋼板溶接継手１に脆性き裂が発生した場合の、き裂伝播方向の制御作用について、以下に説明する。
　図３に示すように、鋼板溶接継手１の長手方向の一方側（図３における縦長方向の上側）で発生した脆性き裂は、鋼板溶接継手１における長手方向の他方側（図３における縦長方向の下側）に向かって伝播を開始する（図３中の二点鎖線矢印を参照）。この際、本実施形態の鋼板溶接継手１（溶接構造体Ａ）では、鋼板溶接継手１、図示例では鋼板継手１１を長手方向で伝播した脆性き裂が傾斜ビード３１に沿って伝播し、その後、図３中の符号Ｆのように、き裂の伝播方向が、傾斜ビード３１の後端３１ｂ付近で鋼板２の母材側に逸れる。そして、鋼板２の母材側に逸れて伝搬するき裂は、脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上の母材領域で停止される。 <Control of propagation direction of brittle crack>
In the welded structure A having the above configuration, the control action of the crack propagation direction when a brittle crack occurs in the steel plate welded joint 1 will be described below.
As shown in FIG. 3, the brittle crack generated on one side in the longitudinal direction of the steel plate welded joint 1 (upper side in the longitudinal direction in FIG. 3) is the other side in the longitudinal direction in the steel plate welded joint 1 (longitudinal direction in FIG. 3). (Below the two-dot chain arrow in FIG. 3). At this time, in the steel plate welded joint 1 (welded structure A) of the present embodiment, a brittle crack propagated in the longitudinal direction in the steel plate welded joint 1, in the illustrated example, in the steel plate joint 11, propagates along the inclined bead 31, and thereafter 3, the crack propagation direction deviates toward the base material side of the steel plate 2 in the vicinity of the rear end 31 b of the inclined bead 31. And the crack which propagates deviating to the base material side of the steel plate 2 is stopped in the base material region where the brittle crack propagation stop characteristic Kca is 4000 N / mm 1.5 or more.
　また、図３に示した脆性き裂とは逆方向の水平ビード３２側から脆性き裂が進展してきた場合でも、図２−ｆのように、突起部４の途中で、脆性き裂の伝播を停止させることができる。 Further, even when the brittle crack has progressed from the side of the horizontal bead 32 opposite to the brittle crack shown in FIG. 3, the propagation of the brittle crack occurs in the middle of the protrusion 4 as shown in FIG. Can be stopped.
　上記作用により、本実施形態の鋼板溶接継手１及び溶接構造体Ａは、例え、鋼板溶接継手１において脆性き裂が発生した場合であっても、脆性き裂が溶接継手や母材を広範囲で伝播するのを抑制できるので、大規模な破壊が発生するのを未然防止することが可能となる。
　このような、本実施形態の鋼板溶接継手１が用いられた溶接構造体Ａを、例えば、大型船舶や建築構造物、土木鋼構造物等の各種溶接構造物に適用することで、溶接構造物の大型化、破壊に対する高い安全性、建造における溶接の高能率化、鋼材の経済性等々を同時に満たすことが可能となる。 Due to the above-described action, the steel plate welded joint 1 and the welded structure A of the present embodiment, even if a brittle crack occurs in the steel plate welded joint 1, causes the brittle crack to spread over the welded joint and the base material in a wide range. Since propagation can be suppressed, it is possible to prevent large-scale destruction from occurring.
By applying the welded structure A in which the steel plate welded joint 1 of the present embodiment is used, for example, to various welded structures such as a large ship, a building structure, and a civil engineering steel structure, a welded structure is obtained. It is possible to simultaneously satisfy the demands for increasing the size of the steel, the high safety against destruction, the high efficiency of welding in construction, the economic efficiency of steel materials, and the like.
＜耐き裂伝播方向制御部の作製方法＞
　以下に、上述したような溶接構造体Ａにおいて、耐脆性き裂伝播方向制御部３を作製する方法の一例について説明する。 <Method of manufacturing crack propagation direction control unit>
Hereinafter, an example of a method for producing the brittle crack propagation direction control unit 3 in the welded structure A as described above will be described.
　鋼板を、相互に突合せ溶接して形成された鋼板溶接継手を有する溶接構造体において、耐脆性き裂伝播方向制御部は、衝突や地震などによる大きな破壊エネルギーにさらされたときに、き裂の発生・伝播が予想される鋼板溶接継手であって、脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上の鋼板により形成されている鋼板溶接継手の途中に、少なくとも１箇所設けられる。 In welded structures with steel plate welded joints formed by butt welding the steel plates, the brittle crack propagation direction control unit is subject to cracking when exposed to large fracture energy due to impact or earthquake. It is a steel plate welded joint which is expected to be generated and propagated, and is provided at least one place in the middle of the steel plate welded joint formed by a steel plate having a brittle crack propagation stop characteristic Kca of 4000 N / mm 1.5 or more.
　該耐脆性き裂伝播方向制御部３は、突合せ溶接された一方の鋼板に突出部４を設け、他方の鋼板に突出部４に対応する形状の切欠き部５を設け、両者を突合せ溶接することで形成される。その際、溶接順序については、特に限定さないが、鋼板溶接継手１１及び鋼板溶接継手１２を先に溶接して形成した後に、耐脆性き裂伝播方向制御部３を溶接して形成するのが一般的である。 The brittle crack propagation direction control unit 3 is provided with a protruding portion 4 on one steel plate butt welded, a notch portion 5 having a shape corresponding to the protruding portion 4 on the other steel plate, and butt-welding the two. Is formed. At that time, the welding order is not particularly limited, but after the steel plate welded joint 11 and the steel plate welded joint 12 are formed by welding first, the brittle crack propagation direction control unit 3 is formed by welding. It is common.
　上記溶接継手を形成する際に用いる溶接方法としては、鋼板溶接継手１１、１２を形成する溶接には、溶接効率の観点から、エレクトロガスアーク溶接法（ＥＧ溶接法、あるいは２電極ＶＥＧＡ溶接法（２ＶＥＧＡ）等）、サブマージアーク溶接法（ＳＡＷ）のような大入熱溶接を適用し、耐脆性き裂伝播方向制御部３を形成する溶接には、半自動炭酸ガス溶接や手溶接を適用することが好ましい。また、溶接施工治具を適宜適性化することにより、耐脆性き裂伝播方向制御部３を形成する際に、２電極ＶＥＧＡ溶接等の溶接方法をそのまま用いても、本発明の効果を発揮することが可能である。 As a welding method used when forming the above-mentioned welded joint, the electrogas arc welding method (EG welding method or two-electrode VEGA welding method (2VEGA) is used for welding to form the steel plate welded joints 11 and 12 from the viewpoint of welding efficiency. ), Etc.), semi-automatic carbon dioxide welding or manual welding may be applied to welding for forming the brittle crack propagation direction control unit 3 by applying high heat input welding such as the submerged arc welding method (SAW). preferable. In addition, by appropriately optimizing the welding jig, the effect of the present invention is exhibited even when a welding method such as two-electrode VEGA welding is used as it is when the brittle crack propagation direction control unit 3 is formed. It is possible.
　本実施形態においては、上述のように、鋼板２同士を突合せ溶接して鋼板溶接継手１を形成する際の溶接方法及び溶接材料については、特に限定されない。また、脆性き裂伝播を可能な限り抑制し、さらに、鋼板溶接継手１をなす鋼板継手１１、１２及び耐脆性き裂伝播方向制御部３において新たな疲労き裂や脆性き裂の起点が生じるのを防止するため、各溶接継手を、溶接欠陥の無いように、溶接金属で完全に充填することが好ましい。
　上記手順により、図３に示すような、本実施形態の耐脆性き裂伝播性に優れた鋼板溶接継手１並びに溶接構造体Ａを製造することができる。 In the present embodiment, as described above, the welding method and the welding material for forming the steel plate welded joint 1 by butt welding the steel plates 2 are not particularly limited. Further, brittle crack propagation is suppressed as much as possible, and new fatigue cracks and brittle crack starting points are generated in the steel plate joints 11 and 12 and the brittle crack propagation direction control unit 3 forming the steel plate welded joint 1. In order to prevent this, it is preferable to completely fill each welded joint with a weld metal so that there are no weld defects.
According to the above procedure, the steel plate welded joint 1 and the welded structure A having excellent brittle crack propagation properties according to the present embodiment as shown in FIG. 3 can be manufactured.
＜溶接構造体を適用した船舶構造体の一例＞
　上述した溶接構造体Ａを適用した船舶構造体の一例を図４の概略図に示す。
　図４に示すように、船舶構造体７０は、骨材（補強材）７１、デッキプレート（水平部材）７２、船殻内板（垂直部材）７３、船殻外板７４を備えて概略構成される。また、図示例の船舶構造体７０は、船殻内板７３をなす複数の鋼板２同士を突合せ溶接することで形成される鋼板溶接継手１（図４中では図示略）の長手方向の一部に耐脆性き裂伝播方向制御部３が設けられることで、本実施形態の溶接構造体Ａを具備する構造とされている。
　上記構成の船舶構造体７０によれば、本実施形態の溶接構造体Ａの構成を適用することにより、例え、鋼板溶接継手を伝播する脆性き裂が発生した場合であっても、耐脆性き裂伝播方向制御部３により、き裂の伝播方向を効果的に制御できる。これにより、鋼板溶接継手に生じた脆性き裂を安定的に停止させることができ、船殻内板７３、ひいては船舶構造体７０に大規模な破壊が生じるのを防止することが可能となる。 <Example of ship structure to which welded structure is applied>
An example of a ship structure to which the above-described welded structure A is applied is shown in the schematic diagram of FIG.
As shown in FIG. 4, the ship structure 70 includes an aggregate (reinforcing material) 71, a deck plate (horizontal member) 72, a hull inner plate (vertical member) 73, and a hull outer plate 74. The Moreover, the ship structure 70 of the example of illustration is a part of the longitudinal direction of the steel plate welded joint 1 (not shown in FIG. 4) formed by butt welding a plurality of steel plates 2 forming the hull inner plate 73. Since the brittle crack propagation direction control unit 3 is provided in the structure, the welding structure A of the present embodiment is provided.
According to the ship structure 70 having the above-described configuration, by applying the configuration of the welded structure A of the present embodiment, even if a brittle crack propagating through a steel plate welded joint occurs, the brittle resistance The crack propagation direction control unit 3 can effectively control the propagation direction of the crack. Thereby, the brittle crack generated in the steel plate welded joint can be stably stopped, and it is possible to prevent the large-scale destruction from occurring in the hull inner plate 73 and consequently the ship structure 70.
［第２の実施形態］
　以下、本発明の第２の実施形態である溶接構造体Ｂについて、主に図５を参照しながら詳述する。なお、以下の説明において、上述の第１の実施形態の溶接構造体Ａと共通する構成については、同じ符号を付与するとともに、その詳細な説明を省略する。 [Second Embodiment]
Hereinafter, the welded structure B which is the second embodiment of the present invention will be described in detail with reference mainly to FIG. In addition, in the following description, about the structure which is common with the welding structure A of the above-mentioned 1st Embodiment, while giving the same code | symbol, the detailed description is abbreviate | omitted.
　本実施形態の溶接構造体Ｂでは、図５に示すように、耐脆性き裂伝播方向制御部３を母材の一部の領域２０ａ、２０ａの脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上である鋼板２０、２０を突合せ溶接することで鋼板溶接継手１が形成されている場合の例であり、この点で、鋼板２の母材全体が、脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上とされている第１の実施形態の溶接構造体Ａとは異なる。 In the welded structure B of the present embodiment, as shown in FIG. 5, the brittle crack propagation direction control unit 3 has a brittle crack propagation stop characteristic Kca of a part of the base material 20a, 20a of 4000 N / mm 1. This is an example in which the steel plate welded joint 1 is formed by butt welding the steel plates 20 and 20 which are 5 or more, and in this respect, the entire base material of the steel plate 2 has a brittle crack propagation stop characteristic Kca. This is different from the welded structure A of the first embodiment, which is set to 4000 N / mm 1.5 or more.
　溶接構造体Ｂでは、耐脆性き裂伝播方向制御部３を、脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上である領域２０ａに隣接して設ける必要がある。図５では、耐脆性き裂伝播方向制御部の水平ビード３２が領域２０ａに接している例を示している。
　溶接構造体Ｂによれば、鋼板溶接継手１０に脆性き裂が発生した場合、鋼板溶接継手１０を伝播してきたき裂を、耐脆性き裂伝播方向制御部３に備えられる傾斜ビード３１の頂点３１ａ又は後端３１ｂの位置で鋼板２０の母材側に逸らすことができる（図５中の二点鎖線矢印を参照）。そして、第１の実施形態の鋼板溶接継手１及び溶接構造体Ａと同様、鋼板２０の母材側に逸れたき裂は、鋼板２０の前記領域２０ａにおいて直ちに停止するので、鋼板溶接継手１０が破断せず、また、溶接構造体Ｂに大規模な破壊が生じるのを防止することが可能となる。また、本実施形態の鋼板溶接継手１０及び溶接構造体Ｂは、前記領域２０ａが、脆性き裂伝播停止特性Ｋｃａが６０００Ｎ／ｍｍ１．５以上とされていることがより好ましい。 In the welded structure B, it is necessary to provide the brittle crack propagation direction control unit 3 adjacent to the region 20a where the brittle crack propagation stop characteristic Kca is 4000 N / mm 1.5 or more. FIG. 5 shows an example in which the horizontal bead 32 of the brittle crack propagation direction control unit is in contact with the region 20a.
According to the welded structure B, when a brittle crack occurs in the steel plate welded joint 10, the crack that has propagated through the steel plate welded joint 10 is transferred to the apex 31 a of the inclined bead 31 provided in the brittle crack propagation direction control unit 3. Or it can deviate to the base material side of the steel plate 20 in the position of the rear end 31b (refer to the dashed-two dotted line arrow in FIG. 5). And like the steel plate welded joint 1 and the welded structure A of the first embodiment, the crack that has escaped to the base material side of the steel plate 20 immediately stops in the region 20a of the steel plate 20, so that the steel plate welded joint 10 breaks. Moreover, it becomes possible to prevent large-scale destruction in the welded structure B. Moreover, as for the steel plate welded joint 10 and the welding structure B of this embodiment, it is more preferable that the region 20a has a brittle crack propagation stop characteristic Kca of 6000 N / mm 1.5 or more.
［第３の実施形態］
　以下、本発明の第３の実施形態である溶接構造体Ｃについて、主に図６を参照しながら、先の実施形態と共通する部分は省略して説明する。 [Third Embodiment]
Hereinafter, the welded structure C according to the third embodiment of the present invention will be described with reference to FIG. 6, omitting the portions common to the previous embodiment.
　溶接構造体Ｃは、突合せ溶接される鋼板が、複数の小鋼板を突合せ溶接されて形成されている場合の例である。 The welded structure C is an example in which a steel plate to be butt welded is formed by butt welding a plurality of small steel plates.
　本実施形態の鋼板溶接継手１０Ａ及び溶接構造体Ｃでは、図６に示すように、突合せ溶接される鋼板２０Ａ、２０Ａが、鋼板溶接継手１０Ａの長手方向で配列される少なくとも２以上の小鋼板（図６中の符号２１、２２の組と２３、２４の組）からなるとともに、この小鋼板同士を突合せ溶接することで小鋼板溶接継手２５、２６が形成されている。そして、耐脆性き裂伝播方向制御部３０の傾斜ビード３１の後端３１ｂ側に形成される水平ビードは、この小鋼板溶接継手２５、２６を含む構成となっており、鋼板溶接継手１０Ａ及び溶接構造体Ｃは、この点で、上述の第１及び第２の実施形態の鋼板溶接継手１、１０並びに溶接構造体Ａ、Ｂとは異なる。
　また、図６に示す例においては、図示の都合上、小鋼板として４枚の小鋼板２１~２４を示し、小鋼板２１と小鋼板２２とが小鋼板溶接継手２５で接合され、小鋼板２３と小鋼板２４とが小鋼板溶接継手２６で接合されている。また、図示例の溶接構造体Ｃは、小鋼板溶接継手２５、２６が連なって直線状に形成されている。 In the steel plate welded joint 10A and the welded structure C of the present embodiment, as shown in FIG. 6, at least two or more small steel plates (in which the steel plates 20A and 20A to be butt welded are arranged in the longitudinal direction of the steel plate welded joint 10A ( 6 and a pair of 23 and 24), and the small steel plates are butt welded to form small steel plate welded joints 25 and 26. And the horizontal bead formed in the rear-end 31b side of the inclination bead 31 of the brittle crack propagation direction control part 30 becomes a structure containing these small steel plate welded joints 25 and 26, and 10A of steel plate welded joints and welding are comprised. In this respect, the structure C is different from the steel plate welded joints 1 and 10 and the welded structures A and B of the first and second embodiments described above.
In the example shown in FIG. 6, for convenience of illustration, four small steel plates 21 to 24 are shown as small steel plates, and the small steel plate 21 and the small steel plate 22 are joined together by a small steel plate welded joint 25. And the small steel plate 24 are joined by a small steel plate welded joint 26. In the illustrated example, the welded structure C is formed in a straight line by connecting small steel plate welded joints 25 and 26.
　また、本実施形態の鋼板溶接継手１０Ａ及び溶接構造体Ｃは、小鋼板２２及び小鋼板２４をなす母材の脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上とされている一方、小鋼板２１及び小鋼板２３の脆性き裂伝播停止特性Ｋｃａは特に規定しない構成とされている。 Further, in the steel plate welded joint 10A and the welded structure C of the present embodiment, the brittle crack propagation stop characteristic Kca of the base material forming the small steel plate 22 and the small steel plate 24 is set to 4000 N / mm 1.5 or more, The brittle crack propagation stop characteristic Kca of the small steel plate 21 and the small steel plate 23 is not particularly defined.
　本実施形態の鋼板溶接継手１０Ａ及び溶接構造体Ｃによれば、上述の溶接構造体Ａ、Ｂと同様、鋼板溶接継手１０Ａに脆性き裂が発生した場合でも、この脆性き裂を傾斜ビード３１に沿うように伝播させ、傾斜ビード３１の後端３１ｂの位置で鋼板２０Ａの母材側に逸らすことができる（図６中の二点鎖線矢印を参照）。図６に示す例では、鋼板溶接継手１０Ａに発生した脆性き裂が、鋼板２０Ａを構成する小鋼板２１側に逸れている。
　そして、鋼板２０Ａの母材側に逸れたき裂は、脆性き裂伝播停止特性Ｋｃａの高い小鋼板２２において直ちに停止するので、鋼板溶接継手１０Ａが破断せず、また、溶接構造体Ｃに大規模な破壊が生じるのを防止することが可能となる。
　また、本実施形態の鋼板溶接継手１０Ａ及び溶接構造体Ｃは、鋼板２０Ａをなす小鋼板２２、２４の母材が、脆性き裂伝播停止特性Ｋｃａ＝６０００Ｎ／ｍｍ１．５以上であることがより好ましい。 According to the steel plate welded joint 10A and the welded structure C of the present embodiment, similar to the welded structures A and B described above, even when a brittle crack occurs in the steel plate welded joint 10A, the brittle crack is inclined to the bead 31. And can be deflected to the base material side of the steel plate 20A at the position of the rear end 31b of the inclined bead 31 (see the two-dot chain line arrow in FIG. 6). In the example shown in FIG. 6, the brittle crack generated in the steel plate welded joint 10A is deviated to the small steel plate 21 side constituting the steel plate 20A.
And since the crack which deviated to the base material side of steel plate 20A stops immediately in small steel plate 22 with high brittle crack propagation stop characteristic Kca, steel plate welded joint 10A does not break, and large-scale in welded structure C Can be prevented from occurring.
Further, in the steel plate welded joint 10A and the welded structure C according to the present embodiment, the base material of the small steel plates 22 and 24 forming the steel plate 20A has a brittle crack propagation stop characteristic Kca = 6000 N / mm 1.5 or more. More preferred.
［第４の実施形態］
　以下、本発明の第４の実施形態である鋼板溶接継手１０Ｂ並びに溶接構造体Ｄについて、主に図７を参照しながら説明する
　本実施形態の鋼板溶接継手１０Ｂ並びに溶接構造体Ｄは、図７に示すように、鋼板２０Ｂが、鋼板溶接継手１０Ｂの長手方向で配列される少なくとも２以上の小鋼板（図７中の符号３１、３２の組と３３、３４の組）からなるとともに、この小鋼板同士を突合せ溶接することで小鋼板溶接継手３５、３６が形成されている点で、第３の実施形態の鋼板溶接継手１０Ａ及び溶接構造体Ｃと構成が一部共通している。
　また、本実施形態の鋼板溶接継手１０Ｂ並びに溶接構造体Ｄは、鋼板２０Ｂをなす全ての小鋼板３１~３４の母材の脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上とされている。 [Fourth Embodiment]
Hereinafter, the steel plate welded joint 10B and the welded structure D according to the fourth embodiment of the present invention will be described mainly with reference to FIG. 7. The steel plate welded joint 10B and the welded structure D of the present embodiment are shown in FIG. As shown in FIG. 7, the steel plate 20B is made of at least two or more small steel plates (a set of symbols 31, 32 and a set of 33, 34 in FIG. 7) arranged in the longitudinal direction of the steel plate welded joint 10B. A part of the configuration is common to the steel plate welded joint 10A and the welded structure C of the third embodiment in that small steel plate welded joints 35 and 36 are formed by butt welding the steel plates.
Further, in the steel plate welded joint 10B and the welded structure D of the present embodiment, the brittle crack propagation stopping characteristics Kca of the base materials of all the small steel plates 31 to 34 constituting the steel plate 20B are set to 4000 N / mm 1.5 or more. Yes.
　溶接構造体Ｄによれば、上述の鋼板溶接継手１、１０、１０Ａ並びに溶接構造体Ａ~Ｃと同様、鋼板溶接継手１０Ｂに脆性き裂が発生した場合でも、この脆性き裂を傾斜ビード３１の頂点３１ａの位置で鋼板２０Ｂの母材側に逸らすことができる（図７中の二点鎖線矢印を参照）。また、小鋼板３１、３３の、Ｋｃａも高いので、傾斜ビード３１に沿う方向に脆性き裂の伝播方向が変わらない場合でも、小鋼板３１の母材あるいは突起部４に突入したき裂を、小鋼板３１、３３のアレスト性能によって停止できる。さらに、鋼板継手１２側から脆性き裂が進展してきた場合でも、図２−ｆのように、突起部４の途中で、脆性き裂の伝播を停止させることができる。
　この結果、鋼板溶接継手１０Ｂ並びに溶接構造体Ｄに大規模な破壊が生じるのを防止することが可能となる。
　また、本実施形態の鋼板溶接継手１０Ｂ並びに溶接構造体Ｄは、鋼板２０Ｂをなす全ての小鋼板３１~３４の母材が、脆性き裂伝播停止特性Ｋｃａ＝６０００Ｎ／ｍｍ１．５以上であることがより好ましい。 According to the welded structure D, even when a brittle crack is generated in the steel plate welded joint 10B, as in the above-described steel plate welded joints 1, 10, 10A and welded structures A to C, the brittle crack is inclined to the bead 31. Can be displaced to the base material side of the steel plate 20B at the position of the apex 31a (see the two-dot chain line arrow in FIG. 7). Moreover, since Kca of the small steel plates 31 and 33 is also high, even when the propagation direction of the brittle crack does not change in the direction along the inclined bead 31, the crack that has entered the base material of the small steel plate 31 or the protruding portion 4, It can be stopped by the arrest performance of the small steel plates 31 and 33. Furthermore, even when a brittle crack has progressed from the steel plate joint 12 side, the propagation of the brittle crack can be stopped in the middle of the protrusion 4 as shown in FIG.
As a result, it is possible to prevent large-scale destruction from occurring in the steel plate welded joint 10B and the welded structure D.
Further, in the steel plate welded joint 10B and the welded structure D of the present embodiment, the base materials of all the small steel plates 31 to 34 forming the steel plate 20B have a brittle crack propagation stop characteristic Kca = 6000 N / mm 1.5 or more. It is more preferable.
　以下、本発明に係る耐脆性き裂伝播性に優れた溶接構造体の実施例を挙げ、本発明をより具体的に説明するが、本発明は、もとより下記実施例に限定されるものではなく、前、後記の趣旨に適合し得る範囲で適当に変更を加えて実施することも可能であり、それらはいずれも本発明の技術的範囲に含まれるものである。 Hereinafter, examples of the welded structure excellent in brittle crack propagation resistance according to the present invention will be given and the present invention will be described more specifically. However, the present invention is not limited to the following examples. The present invention can be carried out with appropriate modifications within a range that can meet the gist of the preceding and following descriptions, all of which are included in the technical scope of the present invention.
［溶接構造体の製造］
　まず、製鋼工程において溶鋼の脱酸・脱硫と化学成分を制御し、連続鋳造によって下記表１に示す化学成分の鋳塊を作製した。そして、日本海事協会（ＮＫ）規格船体用圧延鋼材ＫＡ３２、ＫＡ３６、ＫＡ４０の規格に準じた製造条件で、前記鋳塊を再加熱して熱間圧延することで、板厚が約５２ｍｍの鋼板を製造した。さらに、この鋼板に対して各種熱処理を施すとともに、この際の条件を制御することにより、母材の脆性き裂伝播停止特性Ｋｃａ（Ｎ／ｍｍ１．５）が種々の値になるように適宜調整した。
　製造した鋼板から、試験片のサイズが５００ｍｍ×５００ｍｍ×板厚のＥＳＳＯ試験（脆性き裂伝播停止試験）片を適宜採取し、−１０℃におけるＫｃａ特性を評価・確認するとともに、鋼板の脆性−延性破面遷移温度ｖＴｒＳ１（℃）を測定した。表１にＫｃａ特性及びｖＴｒＳ１を合わせて示した。 [Manufacture of welded structures]
First, the deoxidation / desulfurization and chemical components of molten steel were controlled in the steel making process, and ingots having chemical components shown in Table 1 below were produced by continuous casting. And by reheating the said ingot and hot-rolling it on the manufacturing conditions according to the standard of the Japan Maritime Association (NK) standard rolled steel materials KA32, KA36, KA40, a steel plate having a thickness of about 52 mm is obtained. Manufactured. Further, various heat treatments are performed on the steel sheet, and the conditions at this time are controlled, so that the brittle crack propagation stop characteristic Kca (N / mm 1.5 ) of the base material is appropriately set to various values. It was adjusted.
From the manufactured steel sheet, an ESSO test (brittle crack propagation stop test) specimen having a test piece size of 500 mm × 500 mm × plate thickness was appropriately collected, and the Kca characteristic at −10 ° C. was evaluated and confirmed, and the brittleness of the steel sheet— The ductile fracture surface transition temperature vTrS1 (° C.) was measured. Table 1 shows the Kca characteristics and vTrS1 together.
　次に、図３、７に示すように、鋼板２の溶接端２ａ、２ｂに、表２、４に示す寸法の傾斜ビードが形成されるように、互いに嵌め合わせ可能な突起部４と切欠き部５を形成し、さらに、適用すべき溶接方法に応じた開先加工を施した。
　次に、表２、４に示す溶接方法及び条件を適用して、まず、鋼板２の溶接端２ａ、２ｂ間の一部を溶接することにより、鋼板継手１１を形成した。そして、表２~５に示す溶接方法及び条件を適用して鋼板２の溶接端２ａ、２ｂ間を溶接することで、耐脆性き裂伝播方向制御部３並びに鋼板継手１２を形成することにより、鋼板溶接継手１を形成し、鋼板２、２を互いに接合した。この際、図８に示すように、耐脆性き裂伝播方向制御部３の後端３１ｂの位置が、鋼板２の下端から１５００ｍｍとなるように調整した。
　なお、溶接方法としては、ＥＧ：一般的なエレクトロガスアーク溶接法、ＶＥＧＡ：　電極の遥動機構を備えた単電極エレクトロガスアーク溶接法、２ＶＥＧＡ：電極の遥動機構を備えた２電極エレクトロガスアーク溶接法、ＳＥＧ：電極の遥動機構を備えた単電極エレクトロガスアーク溶接法、ＳＡＷ：サブマージアーク溶接法、ＣＯ２：炭酸ガスアーク溶接法、ＳＭＡＷ：被覆アーク溶接法を用いた。 Next, as shown in FIGS. 3 and 7, the protrusions 4 and the notches that can be fitted to each other so that inclined beads having the dimensions shown in Tables 2 and 4 are formed at the weld ends 2 a and 2 b of the steel plate 2. The part 5 was formed, and further groove processing was performed according to the welding method to be applied.
Next, the welding method and conditions shown in Tables 2 and 4 were applied, and a steel plate joint 11 was formed by first welding a part between the weld ends 2a and 2b of the steel plate 2. And by applying the welding methods and conditions shown in Tables 2 to 5 and welding the weld ends 2a and 2b of the steel plate 2, the brittle crack propagation direction control unit 3 and the steel plate joint 12 are formed, A steel plate welded joint 1 was formed, and the steel plates 2 and 2 were joined together. At this time, as shown in FIG. 8, the position of the rear end 31 b of the brittle crack propagation direction control unit 3 was adjusted to 1500 mm from the lower end of the steel plate 2.
In addition, as a welding method, EG: General electrogas arc welding method, VEGA: Single electrode electrogas arc welding method provided with the electrode swing mechanism, 2VEGA: Two electrode electrogas arc welding method provided with the electrode swing mechanism , SEG: single electrode electrogas arc welding method with electrode swing mechanism, SAW: submerged arc welding method, CO 2 : carbon dioxide arc welding method, SMAW: coated arc welding method.
　なお、鋼板継手１１、１２、耐脆性き裂伝播方向制御部３の形成箇所においては、新たなき裂の起点が生じるのを防止するため、各溶接継手を溶接金属で完全に充填するように溶接処理を行なった。その後、各継手を冷却することにより、図３に示すような鋼板溶接継手及び溶接構造体（本発明例、比較例）を製造した。また、上記同様に、下記表２~５に示す条件で各鋼板を接合することにより、図５~図７に示すような鋼板溶接継手及び溶接構造体（本発明例、比較例）を製造した。 In addition, in order to prevent a new crack starting point from being generated at the locations where the steel plate joints 11 and 12 and the brittle crack propagation direction control unit 3 are formed, welding is performed so that each weld joint is completely filled with weld metal. Processing was performed. Thereafter, by cooling each joint, a steel plate welded joint and a welded structure (invention example, comparative example) as shown in FIG. 3 were produced. Further, similarly to the above, by welding each steel plate under the conditions shown in the following Tables 2 to 5, steel plate welded joints and welded structures (present invention examples and comparative examples) as shown in FIGS. 5 to 7 were produced. .
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
［評価試験］
　上記手順によって製造した鋼板溶接継手及び溶接構造体について、以下のような評価試験を行った。
　まず、図９に示すような試験装置９０を準備するとともに、上記手順で作製した溶接構造体のサンプルの各々を適宜調整し、試験装置９０に取り付けた。ここで、図８中に示す鋼板溶接継手１に設けたき裂発生部である窓枠８１は、楔をあてがって所定の応力を印加することで強制的に脆性き裂を発生させるためのものであり、切欠き状の先端部は０．２ｍｍ幅のスリット加工を施したものである。 [Evaluation test]
The following evaluation tests were conducted on the steel plate welded joints and welded structures produced by the above procedure.
First, a test apparatus 90 as shown in FIG. 9 was prepared, and each of the samples of the welded structure produced by the above procedure was appropriately adjusted and attached to the test apparatus 90. Here, the window frame 81 which is a crack generating portion provided in the steel plate welded joint 1 shown in FIG. 8 is for forcibly generating a brittle crack by applying a predetermined stress by applying a wedge. Yes, the notch-shaped tip is slitted with a width of 0.2 mm.
　次いで、鋼板溶接継手１の溶接線Ｌと垂直方向に２６２Ｎ／ｍｍ２および３００Ｎ／ｍｍ２の引張応力を付与することにより、鋼板溶接継手１に脆性き裂を発生させた。そして、この脆性き裂を、鋼板溶接継手１（鋼板継手１１）の溶接線Ｌ上で伝播させることにより、溶接構造体の耐脆性き裂伝播性を評価した。この際、脆性き裂発生部は−６０℃以下に冷却したが、脆性き裂伝播部である鋼板溶接継手１の温度は、船舶の一般的な設計温度である−１０℃とした。
　なお、窓枠８１を鋼板継手１２に設け、脆性き裂を下側から耐脆性き裂伝播方向制御部３に突入させる試験も行った。 Then, by applying a weld line L and the direction perpendicular to the tensile stress of 262N / mm 2 and 300N / mm 2 of steel welded joints 1, it was generated brittle crack in the steel plate welded joint 1. And this brittle crack was propagated on the weld line L of the steel plate welded joint 1 (steel plate joint 11), and the brittle crack propagation property of the welded structure was evaluated. At this time, the brittle crack generation part was cooled to −60 ° C. or lower, but the temperature of the steel plate welded joint 1 as the brittle crack propagation part was set to −10 ° C., which is a general design temperature of ships.
In addition, the window frame 81 was provided in the steel plate joint 12, and the test which penetrates a brittle crack into the brittle crack propagation direction control part 3 from the lower side was also done.
　そして、鋼板溶接継手１を伝播した脆性き裂が耐脆性き裂伝播方向制御部３に到達した後、その脆性き裂が伝播する方向及び停止位置を確認し、き裂の伝播、停止の形態を、図２のａ~ｆに対応する以下に示す５段階（ａ~ｆ）で評価し、下記表２に示した。
　［ａ］…脆性き裂が耐脆性き裂伝播方向制御部に到達した後、当該制御部に沿ってき裂が伝播し、その後、当該後端において鋼板の母材側へ突入し、鋼板において直ちに停止した（図２−ａの形態）。
　［ｂ］…脆性き裂が耐脆性き裂伝播方向制御部に到達した後、当該制御部に沿うことなく鋼板の突起部へ進入し、該突起部において直ちに停止した（図２−ｂの形態）。
　［ｃ］…脆性き裂が耐脆性き裂伝播方向制御部に到達した後、当該制御部に沿うことなく鋼板の突起部へ進入、伝播し、そのまま鋼板溶接継手に戻り、再び鋼板溶接継手を伝播した（図２−ｃの形態）。
　［ｄ］…脆性き裂が耐脆性き裂伝播方向制御部に到達した後、当該制御部に沿ってき裂が伝播し、そのまま鋼板溶接継手に沿って戻り、再び鋼板溶接継手を伝播した（図２−ｄの形態）。
　［ｅ］…脆性き裂が耐脆性き裂伝播方向制御部内又は当該制御部に沿って伝播した後、当該後端において鋼板の母材側へ突入し、鋼板を伝播した（図２−ｅの形態）。
　［ｆ］…下側から進展した脆性き裂が耐脆性き裂伝播方向制御部に到達した後、当該突起部において直ちに停止した（図２−ｆの形態）。 And after the brittle crack which propagated the steel plate welded joint 1 arrives at the brittle crack propagation direction control part 3, the direction and stop position which the brittle crack propagates are confirmed, and the form of crack propagation and stop Was evaluated in the following five steps (af) corresponding to a to f in FIG.
[A] ... After the brittle crack reaches the brittle crack propagation direction control section, the crack propagates along the control section, and then enters the base metal side of the steel sheet at the rear end, and immediately in the steel sheet. Stopped (form of FIG. 2-a).
[B]... After the brittle crack has reached the brittle crack propagation direction control section, the brittle crack entered the projection of the steel sheet without following the control section, and immediately stopped at the projection (form of FIG. 2-b ).
[C] ... After the brittle crack reaches the brittle crack propagation direction control part, it enters and propagates into the protrusion of the steel sheet without following the control part, returns to the steel plate welded joint, and again connects the steel welded joint. Propagated (form of FIG. 2-c).
[D] ... After the brittle crack reaches the brittle crack propagation direction control part, the crack propagates along the control part, returns as it is along the steel plate welded joint, and propagates again through the steel plate welded joint (Fig. 2-d form).
[E] ... After the brittle crack propagates in the brittle crack propagation direction control section or along the control section, the brittle crack enters the base metal side of the steel sheet at the rear end and propagates through the steel sheet (in FIG. Form).
[F]... After the brittle crack that propagated from the lower side reached the brittle crack propagation direction control section, it immediately stopped at the projection (form of FIG. 2-f).
　本実施例で用いた鋼板の化学成分組成、鋼板製造条件及び母材の脆性き裂伝播停止特性Ｋｃａ（Ｎ／ｍｍ１．５）の一覧を表１に示すとともに、鋼板溶接継手１を形成する際の溶接条件、脆性き裂伝播方向制御部３の形状、脆性き裂伝播方向制御部３に隣接する小鋼板溶接継手を形成する際の溶接条件、及び、脆性き裂の伝播の評価結果の一覧を表２~５に示す。 Table 1 shows a list of the chemical composition of the steel plate used in this example, the steel plate manufacturing conditions, and the brittle crack propagation stopping property Kca (N / mm 1.5 ) of the base material, and the steel plate welded joint 1 is formed. Welding conditions, the shape of the brittle crack propagation direction control unit 3, the welding conditions when forming a small steel plate welded joint adjacent to the brittle crack propagation direction control unit 3, and the evaluation results of the propagation of the brittle crack The list is shown in Tables 2-5.
［評価結果］
　表２~５に示す本発明例１~１９は、図３に示す第１の実施形態の鋼板溶接継手１及び溶接構造体Ａに関する例であり、本発明例２０~２５は、図６に示す第３の実施形態の鋼板溶接継手１０Ａ及び溶接構造体Ｃに、本発明例２６~３０は、図７に示す第４の実施形態の鋼板溶接継手１０Ｂ及び溶接構造体Ｄに、本発明例３１~３３は、図５に示す第２の実施形態の鋼板溶接継手１０及び溶接構造体Ｂにそれぞれ関する例である。なお、発明例１４、２２、２８は、き裂が下側から耐脆性き裂伝播方向制御部３に突入した例である。
　また、表２に示す比較例１、２は、溶接構造体Ａと同様の構造を有する例であり、比較例３、４は溶接構造体Ｂと同様の構造を、比較例５、６は、溶接構造体Ｃと同様の構造を、比較例７~９は、溶接構造体Ｄと同様の構造をそれぞれ有する例である。なお、比較例６は、下側からき裂が突入した例である。 [Evaluation results]
Invention Examples 1 to 19 shown in Tables 2 to 5 are examples relating to the steel plate welded joint 1 and the welded structure A of the first embodiment shown in FIG. 3, and Invention Examples 20 to 25 are shown in FIG. Invention Examples 26-30 are applied to the steel plate welded joint 10A and welded structure C of the third embodiment, and Examples 31 to 30 are applied to the steel plate welded joint 10B and welded structure D of the fourth embodiment shown in FIG. ~ 33 are examples relating to the steel plate welded joint 10 and the welded structure B of the second embodiment shown in FIG. Inventive Examples 14, 22, and 28 are examples in which the crack entered the brittle crack propagation direction control unit 3 from the lower side.
Comparative Examples 1 and 2 shown in Table 2 are examples having the same structure as the welded structure A, Comparative Examples 3 and 4 have the same structure as the welded structure B, and Comparative Examples 5 and 6 Comparative structures 7 to 9 are examples having the same structure as the welded structure D, and Comparative Examples 7 to 9 are examples having the same structure as the welded structure D. Comparative Example 6 is an example in which a crack entered from the lower side.
　表２~５に示すように、本発明に係る鋼板溶接継手及び溶接構造体（本発明例１~３３）は、脆性き裂の伝播の形態が、全て［ａ］、［ｂ］または［ｆ］となり、き裂の進展を停止させることができた。これにより、本発明の溶接構造体が、溶接継手に脆性き裂が発生した場合であっても、き裂が溶接継手や母材を伝播するのを抑制でき、溶接構造体の破断を防止することが可能であり、耐脆性き裂伝播性に優れていることが確認できた。 As shown in Tables 2 to 5, in the steel plate welded joints and welded structures (Invention Examples 1 to 33) according to the present invention, all forms of brittle crack propagation are [a], [b] or [f It was possible to stop the crack growth. Thereby, even if the welded structure of the present invention is a case where a brittle crack is generated in the welded joint, the crack can be prevented from propagating through the welded joint and the base material, and the welded structure is prevented from being broken. It was confirmed that it was excellent in brittle crack propagation resistance.
　ここで、本発明例１、２、１２~１４、１６、２６は、耐脆性き裂伝播方向制御部３の傾斜ビード３１の角度θが、鋼板溶接継手１の長手方向に対して３０°以下、あるいは４５°以上であったため、き裂が、耐脆性き裂伝播方向制御部３から鋼板２の母材（突起部４）に突入し、鋼板２にて停止した例である。
　また、それ以外の本発明例においては、耐脆性き裂伝播方向制御部３に到達した脆性き裂が、当該制御部に沿って伝播した後、鋼板の母材に突入して直ちに停止した例である。
　このように、上記本発明例１~３３の鋼板溶接継手及び溶接構造体は、何れも、所定の耐脆性き裂伝播性を有していることが確認できた。 Here, in the inventive examples 1, 2, 12-14, 16, and 26, the angle θ of the inclined bead 31 of the brittle crack propagation direction control unit 3 is 30 ° or less with respect to the longitudinal direction of the steel plate welded joint 1. Alternatively, since the angle is 45 ° or more, the crack enters the base material (projection 4) of the steel plate 2 from the brittle crack propagation direction control unit 3 and stops at the steel plate 2.
In other examples of the present invention, the brittle crack that reached the brittle crack propagation direction control unit 3 propagated along the control unit, and then entered the base material of the steel plate and immediately stopped. It is.
As described above, it was confirmed that each of the steel plate welded joints and welded structures of Examples 1-33 of the present invention had a predetermined brittle crack propagation resistance.
　これに対し、比較例１~９の溶接構造体は、鋼板の母材特性、耐脆性き裂伝播方向制御部の形状の何れかが本発明の規定を満たしていないため、耐脆性き裂の伝播の形態が［ｃ］~［ｅ］の形態となり、脆性き裂の伝播を停止できなかった例である。 On the other hand, in the welded structures of Comparative Examples 1 to 9, either the base material characteristics of the steel plate or the shape of the brittle crack propagation direction control part does not satisfy the provisions of the present invention. This is an example in which the propagation forms are [c] to [e] and the propagation of brittle cracks could not be stopped.
　比較例１、７~９の溶接構造体は、耐脆性き裂伝播方向制御部近傍で鋼板母材側に突入した脆性き裂が母材部で停止できず、再び溶接継手に突入して伝播し、評価が若干低い［ｃ］となった例であるが、比較例１は、傾斜ビード３１の角度θが５０°を超えたため、比較例７は、耐脆性き裂伝播方向制御部の高さＨが不充分で、かつ、横幅Ｗが上記（２）式を満たさないため、比較例８、９は、小鋼板溶接継手をなす溶接金属部が鋼板溶接継手となす角度θ２が、８０°未満あるいは１１０°を超えたため、そのような結果になった。
　また、比較例２は、傾斜ビードの角度が不足し、かつ、横幅Ｗが上記（２）式を満たさないため、また比較例６は、鋼板の母材のアレスト性能が不充分であったため、耐脆性き裂伝播方向制御部に沿って伝播方向を変えた脆性き裂が再び鋼板溶接継手を伝播し、［ｄ］となった例である。
　また、比較例３~５は、鋼板の母材のアレスト性能が不充分であったため、耐脆性き裂伝播方向制御部にて脆性き裂の伝播方向を制御できたのにも関わらず、鋼板の母材に突入した脆性き裂がそのまま伝播し、［ｅ］となった例である。 In the welded structures of Comparative Examples 1 and 7-9, the brittle crack that entered the steel plate base in the vicinity of the brittle crack propagation direction control part could not be stopped at the base part, but entered the weld joint again and propagated. In this example, the evaluation was slightly lower [c]. However, in Comparative Example 1, since the angle θ of the inclined bead 31 exceeded 50 °, Comparative Example 7 was a high resistance of the brittle crack propagation direction control unit. Since the height H is insufficient and the width W does not satisfy the above formula (2), in Comparative Examples 8 and 9, the angle θ2 between the weld metal part forming the small steel plate welded joint and the steel plate welded joint is 80 °. Such a result was obtained because of less than or exceeding 110 °.
In Comparative Example 2, the angle of the inclined bead is insufficient, and the width W does not satisfy the above formula (2). In Comparative Example 6, the arrest performance of the base material of the steel plate is insufficient. This is an example in which a brittle crack whose propagation direction has been changed along the brittle crack propagation direction control unit propagates again through the steel plate welded joint and becomes [d].
In Comparative Examples 3 to 5, since the arrest performance of the base material of the steel plate was insufficient, the steel plate was able to control the propagation direction of the brittle crack in the brittle crack propagation direction control unit. This is an example in which a brittle crack that has entered the base metal propagates as it is and becomes [e].
　以上の結果により、本発明の鋼板溶接継手及び溶接構造体が、溶接継手に脆性き裂が発生した場合であっても、き裂が溶接継手や母材を伝播するのを抑制でき、溶接構造体の破断を防止することが可能であり、耐脆性き裂伝播性に優れていることが明らかである。 From the above results, the steel plate welded joint and welded structure of the present invention can suppress the propagation of the crack through the welded joint and the base material even when a brittle crack occurs in the welded joint. It is clear that the body can be prevented from breaking and is excellent in brittle crack propagation resistance.
　１、１０、１０Ａ、１０Ｂ　鋼板溶接継手
　Ａ、Ｂ、Ｃ、Ｄ　溶接構造体
　２、２０、２０Ａ、２０Ｂ　鋼板
　２０ａ　領域（鋼板溶接継手の長手方向において、該鋼板溶接継手の溶接線上から延在する耐脆性き裂伝播方向制御部の傾斜ビードの後端側よりも外側の部位）
　３、３０　耐脆性き裂伝播方向制御部
　３１　傾斜ビード
　３２　水平ビード
　３１ｂ　後端（傾斜ビード）
　４　鋼板の突起部
　５　鋼板の切欠き部
　２５、２６、３５、３６　小鋼板溶接継手
　２１、２２、２３、２４、３１、３２、３３、３４　小鋼板
　７０　船舶構造体
　Ｌ　溶接線
　Ｈ　傾斜ビードの鋼板溶接継手の長手方向に沿った高さ
　Ｗ　傾斜ビードの鋼板溶接継手の長手方向と交差する方向における横幅 1, 10, 10A, 10B Steel plate welded joint A, B, C, D Welded structure 2, 20, 20A, 20B Steel plate 20a region (extending from the weld line of the steel plate welded joint in the longitudinal direction of the steel plate welded joint) The part outside the rear end of the inclined bead of the brittle crack propagation direction control part)
3, 30 Brittle crack propagation direction control unit 31 Inclined bead 32 Horizontal bead 31b Rear end (inclined bead)
4 Steel plate protrusion 5 Steel plate notch 25, 26, 35, 36 Small steel plate welded joint 21, 22, 23, 24, 31, 32, 33, 34 Small steel plate 70 Ship structure L Welding line H Inclined bead Height along the longitudinal direction of the steel plate welded joint W Width in the direction intersecting the longitudinal direction of the steel plate welded joint of the inclined bead

Claims (6)

  1. 　少なくとも一部の領域の脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上である鋼板を、互いに突合せ溶接することで鋼板溶接継手が形成されてなる溶接構造体において、
    　前記鋼板溶接継手の少なくとも一箇所に、鋼板溶接継手に発生した脆性き裂の伝播を制御する耐脆性き裂伝播方向制御部が設けられており、
    　該耐脆性き裂伝播方向制御部は、一方の鋼板に形成された突起部と、それに対向する他方の鋼板との間で突合せ溶接されて形成された傾斜ビードを有しており、
    　該傾斜ビードは、前記鋼板溶接継手の溶接線上からその長手方向に延伸するとともに、鋼板溶接継手の長手方向に対して１５°以上５０°以下の範囲の角度で傾斜しており、かつ、傾斜ビードの後端部は、少なくとも、前記鋼板のＫｃａが４０００Ｎ／ｍｍ１．５以上である領域に向かい合うように形成されていること、を特徴とする耐脆性き裂伝播性に優れた鋼板溶接継手。     In a welded structure in which a steel plate welded joint is formed by butt welding the steel plates having a brittle crack propagation stopping property Kca of at least a part of the region of 4000 N / mm 1.5 or more,
    At least one location of the steel plate welded joint is provided with a brittle crack propagation direction control unit that controls the propagation of a brittle crack generated in the steel plate welded joint,
    The brittle crack propagation direction control part has an inclined bead formed by butt welding between a protrusion formed on one steel plate and the other steel plate facing it,
    The inclined bead extends in the longitudinal direction from the weld line of the steel plate welded joint, and is inclined at an angle in the range of 15 ° to 50 ° with respect to the longitudinal direction of the steel plate welded joint. A steel plate welded joint excellent in brittle crack propagation resistance, characterized in that the rear end portion is formed so as to face at least a region where Kca of the steel plate is 4000 N / mm 1.5 or more.
  2. 　前記耐脆性き裂伝播方向制御部に備えられる前記傾斜ビードは、前記鋼板溶接継手の長手方向に沿った高さＨ（ｍｍ）、鋼板溶接継手の長手方向と交差する方向における横幅Ｗ（ｍｍ）の各々の寸法が、下記（１）、（２）式で表される関係を満足すること、を特徴とする請求項１に記載の耐脆性き裂伝播性に優れた鋼板溶接継手。
    　２Ｔ　≦　Ｈ　　　　・・・・・　（１）
    　ｄ＋５０　≦　Ｗ　　・・・・・　（２）
    　但し、上記（１）、（２）式中において、Ｔは前記鋼板の板厚（ｍｍ）を表し、ｄは前記鋼板溶接継手における溶接金属部の幅（ｍｍ）を表す。     The inclined bead provided in the brittle crack propagation direction control unit has a height H (mm) along the longitudinal direction of the steel plate welded joint and a lateral width W (mm) in a direction intersecting the longitudinal direction of the steel plate welded joint. The steel plate welded joint with excellent brittle crack propagation resistance according to claim 1, wherein each of the dimensions satisfies a relationship represented by the following formulas (1) and (2):
    2T ≤ H (1)
    d + 50 ≦ W (2)
    However, in said Formula (1) and (2), T represents the plate | board thickness (mm) of the said steel plate, and d represents the width | variety (mm) of the weld metal part in the said steel plate welded joint.
  3. 　前記鋼板の板厚が２５ｍｍ以上１５０ｍｍ以下であること、を特徴とする請求項１又は請求項２に記載の耐脆性き裂伝播性に優れた鋼板溶接継手。 The steel plate welded joint having excellent brittle crack propagation resistance according to claim 1 or 2, wherein the steel plate has a thickness of 25 mm or more and 150 mm or less.
  4. 　前記鋼板は、少なくとも一部の領域の脆性き裂伝播停止特性Ｋｃａが６０００Ｎ／ｍｍ１．５以上であり、前記傾斜ビードの後端部は、少なくとも、前記鋼板のＫｃａが６０００Ｎ／ｍｍ１．５以上である領域に向かい合うように形成されていること、を特徴とする請求項１~３の何れか１項に記載の耐脆性き裂伝播性に優れた鋼板溶接継手。 The steel sheet has a brittle crack propagation stop characteristic Kca of at least a partial region of 6000 N / mm 1.5 or more, and the rear end of the inclined bead has at least a Kca of 6000 N / mm 1.5 of the steel sheet. The steel plate welded joint having excellent brittle crack propagation resistance according to any one of claims 1 to 3, wherein the steel welded joint is formed so as to face the above region.
  5. 　前記鋼板は、前記鋼板溶接継手の長手方向で配列される少なくとも２以上の小鋼板からなるとともに、該小鋼板を互いに突合せ溶接することで小鋼板溶接継手が形成されており、前記小鋼板溶接継手は、前記鋼板溶接継手の溶接線上から延在する前記耐脆性き裂伝播方向制御部の、前記傾斜ビードの後端側に形成される水平ビードを含むこと、を特徴とする請求項１~４の何れか１項に記載の耐脆性き裂伝播性に優れた鋼板溶接継手。 The steel plate is composed of at least two or more small steel plates arranged in the longitudinal direction of the steel plate welded joint, and a small steel plate welded joint is formed by butt welding the small steel plates to each other. 5. A horizontal bead formed on the rear end side of the inclined bead of the brittle crack propagation direction control portion extending from the weld line of the steel plate welded joint. The steel plate welded joint excellent in the brittle crack propagation property of any one of these.
  6. 　母材の少なくとも一部の脆性き裂伝播停止特性Ｋｃａが４０００Ｎ／ｍｍ１．５以上である鋼板同士を突合せ溶接することで鋼板溶接継手が形成されてなる溶接構造体であって、該鋼板溶接継手の少なくとも１箇所に、上記請求項１~５の何れか１項に記載の耐脆性き裂伝播方向制御部が設けられていること、を特徴とする耐脆性き裂伝播性に優れた溶接構造体。 A welded structure in which a steel plate welded joint is formed by butt welding two or more steel plates having a brittle crack propagation stop characteristic Kca of 4000 N / mm 1.5 or more of a base material, the steel plate welding A weld having excellent brittle crack propagation characteristics, characterized in that the brittle crack propagation direction control section according to any one of claims 1 to 5 is provided at least at one location of the joint. Structure.
PCT/JP2010/062277 2010-07-14 2010-07-14 Welded joint and welded structure having excellent brittle crack propagation resistance WO2012008055A1 (en)

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