抄録
This paper deals with the strengthening of spot-welded lap joints through the formation of a new hardened zone (HAZ). The factors needed for strengthening were determined via a previously proposed equation predicting the strength. Using these factors, the strengthening of spot-welded lap joints was examined. First, in order to increase the hardened zone, the edge of the nugget was heated with a laser. Next, cross-tension tests were conducted by using spot-welded lap joints that were heated by a laser at various distances from the nugget. It was found that the fracture position and the cross-tension strength (CTS) were governed by whichever was higher: the strength outside HAZ or the strength at the nugget's edge. It was also shown that the cross-tension strength could be improved by 10%.
