METHOD OF RESISTANCE SPOT WELDING AND METHOD OF EVALUATING WELDED JOINT MANUFACTURED BY METHOD OF RESISTANCE SPOT WELDING

摘要

The present invention aims to provide a resistance spot welded joint of high strength without detaching and softening of peeled-off rupture by making it difficult to generate cracks by reducing the segregation of the nugget with respect to two or more sheet sets The purpose. In a resistance spot welded joint of a thin steel sheet, when the diameter of a nugget constituted by a thin steel sheet is d, a dug portion is formed on the horizontal plane of the nugget surrounded by the corona bond, / 100 and the distribution of the amount of P present in the nugget region enclosed by the closed curve of the distance of d / 5 is analyzed, and the concentration m (mass%) of P is calculated from the concentration of P Wherein an area ratio exceeding 2 times of M (mass%) is 5% or less.