Search

CN-117241907-B - Welded structure

CN117241907BCN 117241907 BCN117241907 BCN 117241907BCN-117241907-B

Abstract

The present invention relates to a welded structure comprising a T-joint in which an end face of a joining member is abutted against a surface of a member to be joined having a plate thickness of 50mm or more, the joining member and the member to be joined are joined together, and a weld metal of the T-joint has a predetermined weld metal composition and a weld metal structure in which an austenite phase is 80% or more in area%.

Inventors

  • Habao ryota
  • HANDA TSUNEHISA
  • Yi Mucong

Assignees

  • 杰富意钢铁株式会社

Dates

Publication Date
20260505
Application Date
20220614
Priority Date
20210615

Claims (15)

  1. 1. A welded structure comprising a T-joint for abutting an end surface of a joining member against a surface of a joined member having a plate thickness of 50mm or more, joining the joining member and the joined member, The longer one of the leg length and the welding width of the T joint has a value L of 16mm or more, The weld metal of the T-joint has the following weld metal composition and weld metal structure: The weld metal composition comprises, by mass%, 0.10 to 0.70% of C, 0.10 to 1.00% of Si, 15.00 to 28.00% of Mn, 0.030% or less of P, 0.015% or less of S, 1.00 to 5.00% of Ni, 0.50 to 4.00% of Cr, 2.00% or less of Mo, 0.150% or less of N, and 0.050% or less of O, as the remainder Fe and unavoidable impurities, The austenite phase in the weld metal structure is 80% or more in area%.
  2. 2. A welded structure comprising a T-joint for abutting an end surface of a joining member against a surface of a joined member having a plate thickness of 50mm or more, joining the joining member and the joined member, The longer one of the leg length and the welding width of the T joint has a value L of 16mm or more, The weld metal of the T-joint has the following weld metal composition and weld metal structure: The weld metal composition comprises, in mass%, 0.10 to 0.70% of C, 0.10 to 1.00% of Si, 15.00 to 28.00% of Mn, 0.030% or less of P, 0.015% or less of S, 1.00 to 5.00% of Ni, 0.50 to 4.00% of Cr, 2.00% or less of Mo, 0.150% or less of N, and 0.050% or less of O, at least one of the following (a) and (b) in mass%, fe and unavoidable impurities as the remainder, (A) 1 or 2 or more selected from the group consisting of 0.10% or less of V, 0.10% or less of Ti and 0.10% or less of Nb, and (B) 1 or 2 or more selected from Cu 1.00% or less, al 0.10% or less, ca 0.010% or less and REM 0.020% or less, The austenite phase in the weld metal structure is 80% or more in area%.
  3. 3. The welded structure according to claim 1, wherein an unfused portion is present on a surface of the T-joint where an end surface of the joining member is abutted against a surface of the joined member, and a ratio of a width of the unfused portion to a plate thickness of the joining member, that is, an unfused ratio Y is 30% or more.
  4. 4. The welded structure according to claim 2, wherein a non-welded portion is present on a surface of the T-joint where an end surface of the joining member is abutted against a surface of the joined member, and a ratio of a width of the non-welded portion to a plate thickness of the joining member, i.e., a non-welded ratio Y is 30% or more.
  5. 5. The welded structure according to claim 1, wherein the member to be joined has a welding head portion so as to intersect the joining member.
  6. 6. The welded structure according to claim 2, wherein the member to be joined has a welding head portion so as to intersect the joining member.
  7. 7. The welded structure according to claim 3, wherein the member to be joined has a welding head portion so as to intersect the joining member.
  8. 8. The welded structure according to claim 4, wherein the member to be joined has a welding head portion so as to intersect the joining member.
  9. 9. The welded structure according to claim 5, wherein the joining member has a butt-welding head, and the joining member is disposed so that the butt-welding head of the joining member intersects the butt-welding head of the joined member.
  10. 10. The welded structure according to claim 6, wherein the joining member has a butt-welding head, and the joining member is disposed so that the butt-welding head of the joining member intersects the butt-welding head of the joined member.
  11. 11. The welded structure according to claim 7, wherein the joining member has a butt-welding head, and the joining member is disposed so that the butt-welding head of the joining member intersects the butt-welding head of the joined member.
  12. 12. The welded structure according to claim 8, wherein the joining member has a butt-welding head, and the joining member is disposed so that the butt-welding head of the joining member intersects the butt-welding head of the joined member.
  13. 13. The welded structure according to any one of claims 1 to 12, wherein a plate thickness of the joint member is 50mm or more.
  14. 14. The welded structure according to any one of claims 1 to 12, wherein a gap between the joining member and the joined member is 10mm or less.
  15. 15. The welded structure according to claim 13, wherein a gap between the joining member and the joined member is 10mm or less.

Description

Welded structure Technical Field The present invention relates to a welded steel structure (hereinafter, also referred to as a welded structure) that is welded using a thick steel plate, for example, in a large container ship, a bulk carrier, or the like. The present invention relates to a welded structure having excellent brittle crack propagation stopping characteristics, in which propagation of brittle cracks generated from a base material of a thick steel plate or a welded joint portion can be stopped before the propagation reaches a large-scale fracture of the structure. Background Container ships and bulk carriers have a structure for enlarging an opening in the ship, unlike tankers and the like, for example, in order to improve loading capacity and loading efficiency. Therefore, in container ships and bulk cargo ships, it is particularly necessary to increase the strength or thickness of the hull plate. In addition, container ships have recently become larger in size, and large ships such as 6000 to 24000teu have been constructed. The TEU (TWENTY FEET equipment Unit) represents the number of containers converted to 20 feet in length, and represents an index of the loading capacity of the container ship. With the increase in size of such ships, the hull plates tend to be made of thick steel plates having a plate thickness of 50mm or more and a yield strength of 390N/mm 2 or more. In recent years, from the viewpoint of shortening the construction period, steel plates as hull outer plates are often butt-welded by, for example, high heat input welding such as arc welding. Such high heat input welding is likely to cause a significant decrease in toughness of the welding heat affected zone, and is one cause of brittle cracks in the welded joint. On the other hand, in the hull structure, in the past, from the viewpoint of safety, even in the event of brittle fracture, it is considered necessary to stop propagation of brittle cracks before large-scale fracture is reached, and prevent separation of the hulls. With this thought in mind, non-patent document 1 reports experimental results of the propagation behavior of brittle cracks in welded portions in steel sheets for ship building, which have a sheet thickness of less than 50 mm. In non-patent document 1, propagation paths and propagation behaviors of brittle cracks forcibly generated in welded portions are experimentally examined. It is described therein that if the fracture toughness of the welded portion is ensured to some extent, brittle cracks often deviate from the welded portion to the base material side due to the influence of the welding residual stress. Among them, an example in which a plurality of brittle cracks propagate along the welded portion was also confirmed. This suggests that the possibility of brittle fracture propagation along the weld is not asserted. However, in addition to a plurality of results in which a ship constructed by applying the same welding as that applied in non-patent document 1 to a steel sheet having a sheet thickness of less than 50mm is put into practical use without any problem, it is recognized that a steel sheet base material (shipbuilding E-grade steel or the like) having good toughness sufficiently maintains the ability to stop brittle cracks, and thus the brittle crack propagation stopping characteristics of the welded portion of the ship steel material are not particularly required in the shipgrade regulations or the like. In large container ships exceeding 6000TEU in recent years, the thickness of steel plates used may exceed 50mm. In this case, in addition to the decrease in fracture toughness due to the increase in plate thickness, the fracture toughness of the welded portion tends to be further decreased by welding with a large line energy having a larger weld line energy. In a thick-wall high heat input welded joint obtained by performing high heat input welding on a steel plate having a thickness exceeding 50mm, brittle cracks generated from a welded portion may progress without being deviated to a base material side, and may not stop at a steel plate base material portion such as a bone material. This is described in, for example, non-patent document 2. Therefore, ensuring the safety of a ship structure to which a thick high-strength steel plate having a thickness of 50mm or more is applied is a major problem. In addition, non-patent document 2 discloses that a thick steel plate having a special brittle crack propagation stopping characteristic is required in order to stop propagation of the brittle crack generated. In order to solve such a problem, for example, patent document 1 describes a welded structure, which is preferably a hull outer plate having a plate thickness of 50mm or more, in which bone material is arranged so as to intersect with butt weld joints, and joined by fillet welding. In the technique described in patent document 1, by forming a structure in which a steel plate having a prede