| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of spot welding of high tensile steel plate and equipment for the method by which the generation of expulsion caused by a rapid increase in electric resistance due to a large hardness of a tensile steel plate and the poor fitness in the earlier stage of welding is suppressed, a sufficient nugget diameter is assured, the generation limit of the expulsion is expanded, an electric current path is surely secured, and the generation of crack is prevented by relaxing the decrease in the gradient of hardness of a heat-affected zone (HAZ) and a stress concentration due to the expansion of the HAZ. SOLUTION: The spot welding is performed in a process which is provided with a first step S1 in which a nugget is generated by gradually increasing a supplied current to the high tensile steel plate, a second step S2 in which the supplied current is decreased after the first step S1, and a third step S3 in which a regular welding is performed by increasing the electric current after the second step S2 and the supplied current is gradually decreased. COPYRIGHT: (C)2003,JPO |
