RESIDUAL STRESS-IMPROVING WELDING METHOD, AND WELDED STRUCTURE

PROBLEM TO BE SOLVED: To provide a residual stress-improving welding method which is effective for preventing stress corrosion crack or the like by improving the residual stress exerted in a back bead part on a back side formed by the single side welding of a tubular member or a plate member of a bevel joint, and a part in a vicinity thereof into the compressive stress, and a welded structure by the method. SOLUTION: In the residual stress improving welding method, the residual stress in a back bead part on a back side formed by the single side welding of joint members 1, 2 of a bevel formed by butting a tubular member or a plate member, and a part in the vicinity thereof is improved into the compressive stress. After forming a back bead 15 on the back side of a bevel bottom part in a first pass weld, the lamination welding 41 is performed to the specified lamination bead height Hb within a heat input range Q1 of ≥ 4 kJ/cm and ≤ 12 kJ/cm, and then, the lamination welding 42 is performed from a remaining bevel portion to the final layer of an upper portion of the bevel within the heat input range Q2 of ≥ 2 kJ/cm and ≤ 6 kJ/cm to form a compressive residual stress in the back bead part and a heat-affected zone in the vicinity thereof. Alternatively, the compressive residual stress with slight tensile stress being mixed in a part of the back bead is exerted in the heat-affected zone. COPYRIGHT: (C)2007,JPO&INPIT