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US 2013/0153092 A1Published application
Method of production of welded joint
AssigneeNippon Steel Corporation
InventorsTadashi Kasuya, Ryuichi Shimura, Manabu Mizumoto
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AssigneeNippon Steel Corporation
InventorsTadashi Kasuya, Ryuichi Shimura, Manabu Mizumoto
Estimating the term…
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.
A method of production of a welded joint which welds joining parts of steel materials by multipass welding, the method of production of a welded joint characterized in that said multipass welding comprises a first weld step of welding by a first pass using a welding material with a transformation start temperature of the weld metal of 175° C. to 400° C. in range and a second weld step of then welding to build up the weld metal by one pass or two passes or more so that parts of the weld metal which was formed in said first weld step become unmelted parts, in which second weld step the weld heat of the final pass causing said unmelted part to completely retransform to austenite.
A method of production of a welded joint which welds joining parts of steel materials by multipass welding, the method of production of a welded joint characterized in that said multipass welding comprises a first weld step of welding by a first pass using a welding material with a transformation start temperature of the weld metal of 175° C. to 400° C. in range and a second weld step of then welding to build up the weld metal by one pass or two passes or more so that parts of the weld metal which was formed in said first weld step become unmelted parts and has a step of then applying heat treatment which causes said unmelted part to completely retransform to austenite.
Dependencies are inferred from the claim text.