超微細粒高強度鋼板のスポット溶接特性

抄録

Resistance spot welding was carried out for ultra-fine grained high strength steel sheets to investigate the characteristics of the weld. The steel sheets have a low carbon equivalent in order to retain good weldability and realize high strength by means of their ultra-fine grained microstructure. Ultra-fine grained high strength steel sheets require higher welding current in comparison with normal high strength steel sheets in order to create the same size nugget. It depends upon the difference of resistivity and strength at high temperature. On condition that the same size nugget is created, there is no difference of tensile shear strength and cross tention strength between ultra-fine grained high strength steel sheets and normal high strength steel sheets.