Welded structure comprising a large-heat-input butt welded joint having controlled hardness and controlled size of the heat affected zone for excellent brittle fracture resistance

摘要

The present application relates to a large-heat-input butt-welded joint comprising welded structures and a butt-welded joint prepared by butt-welding high-strength steel plates over 50 mm in thickness having yield strength of 390 MPa class and 460 MPa class for ship structural application, having excellent brittle fracture resistance, is defined by:
(a) the hardness of the weld metal is not less than 70% and not more than 110% of the hardness of the base metal, and
(b) the width of the weld metal is not more than 70% of the plate thickness of the base metal,
wherein the width of the region affected by welding whose hardness is softened to not more than 95% of the hardness of the base metal unaffected by heat has a width not less than 5 mm.