Method of production of welded joint

摘要

A method of production of a welded joint which enables improvement of the fatigue strength in the case where measures for improvement of the fatigue strength cannot be applied due to the presence of structurally sealed regions is provided. The method is provided with a first weld step which performs welding by forming an inside weld toe or root part by using a weld metal with a transformation start temperature of 175° C. to 400° C. in range, at least parts of the weld metal forming the inside weld toe or root part which was formed at the first weld step becoming unmelted parts, and a second weld step which performs welding for building up the weld metal by a single pass by a weld heat input by which all of the unmelted parts are retransformed to austenite so as to introduce compressive residual stress to the inside weld toe or root part.

主权项

1. A method of production of a welded joint comprising joining parts of steel materials by multipass welding, the welded joint having an inside weld toe or a root part, the inside weld toe or the root part being sealed off in structure the welded joint being able to be welded from one side only, the method of production comprising:
a first weld step of forming a welding metal including the inside weld toe or the root part using a welding material having a transformation start temperature in the range of 175° C. to 400° C.; and a second weld step of welding to build up the welding metal by one, two, or more passes from an opposite side of the inside weld toe or the root part of the welding metal so that at least parts of the welding metal which were formed in said first weld step become unmelted parts, wherein, during the second weld step, the weld heat of the final pass causes the welding metal including the inside weld toe or the root part, which was formed in the first weld step, to completely retransform to austenite.