METHOD OF MULTI-LAYER WELDING, AND STRUCTURE FORMED BY MULTI-LAYER WELDING

PROBLEM TO BE SOLVED: To excellently perform a multi-layer welding operation for stacking welding layers from a first layer penetration welding at the bottom portion of a groove necessary for a groove joint of a thick plate to a final layer welding at the upper surface portion of the groove, and further to convert a residual tensile stress remaining in the welded portions on the back surface side and the outside surface side after finishing the welding into a compressive stress or to remarkably reduce the residual tensile stress. SOLUTION: The multi-layer welding for stack-welding stainless steel using two wires made of different materials is performed for a groove joint in which cylindrical members or flat plate members are butted to each other. The multi-layer welding comprises a step of primary layer penetration welding process (primary layer penetration bead forming process) for forming a penetration bead on the back surface side at the bottom portion of the groove in the primary layer welding or the primary layer welding after the tack welding, a step of a first stack welding process for performing a stack welding process using an austenitic wire, which is the same material as that of the groove joint, until the accumulated stacked bead height from the back surface of the groove reaches to a first specified range, and a step of a second stack welding process for performing a stack welding process using a martensitic wire from the remaining welding portion up to the final layer on the upper surface portion of the bevel. COPYRIGHT: (C)2006,JPO&NCIPI