| 摘要 |
PROBLEM TO BE SOLVED: To form a welded joint which is sufficiently high in fracture toughness value Kc by butt welding a high-strength steel plate for welding for hulls which is of a 460 MPa class in yield strength and is more than 50 mm in plate thickness. SOLUTION: In the butt-welded joint of a welded structure, (a1) hardness of a weld metal is 110% or less of hardness of a base material or (a2) hardness of the weld metal is 70% or more but 110% or less of hardness of the base material, and when needed, a width of the weld metal is 70% or less of a plate thickness of the base material, (c) a width of a region of an affected portion by welding which is softened into hardness of 95% or less of hardness of the base material not affected by heat is 5 mm or more, and/or (d) an austenitic grain size of the affected portion by welding (HAZ) which comes into contact with a weld fusion line is 200μm or less, by which the high heat input butt-welded joint excellent in resistance to brittle fracture generation is obtained. COPYRIGHT: (C)2005,JPO&NCIPI |
