| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a steel sheet welded part excellent in delayed fracture resistance, and also to provide a steel structure having the welded part. SOLUTION: A plurality of steel sheets are lapped or abutted, laser beam is irradiated to a surface of an uppermost steel sheet of a lapped part and an abutted part, and when forming the welded part while melting the steel sheets to the rear surface of a lowermost steel sheet, laser beam is re-irradiated once or more times to welded metal in such a way as not to penetrate the rear surface of the lowermost steel sheet in contact with the atmosphere while supplying shielding gas with an absolute humidity of≤2 g/m<SP POS="POST">3</SP>to the welded part of the surface of the uppermost steel sheet within 10 minutes after the welded part is formed, and the welded metal is re-melted by the number of times of irradiation. COPYRIGHT: (C)2013,JPO&INPIT |
