SPOT WELD ZONE, MANUFACTURING METHOD OF SPOT WELD ZONE, AND STRENGTH JUDGEMENT METHOD OF SPOT WELD ZONE

摘要

PROBLEM TO BE SOLVED: To provide a spot weld zone for imparting excellent static strength, impact strength and fatigue strength to a weld joint or a welding member; and to provide a manufacturing method thereof, and a strength judgement method.SOLUTION: In a spot weld zone, which is a spot weld zone on a weld joint and a welding member, formed by spot-welding two or more thin steel sheets having a board thickness of t[mm], a nugget diameter[mm] is 3√t or larger, and, on a nugget cross section, a convex salient is provided in the opposite direction to the nugget in a sheet separation end region, and a contour line of the salient is intersected with a straight line connecting each steel sheet mating surface of the thin steel sheet, and the salient comprises a welding heat affected zone as much as 50% or more in terms of the area ratio.SELECTED DRAWING: Figure 5