| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing a resistance spot welded joint by which a nugget with a required size is formed without adding an excessive process and without generating expulsion, even in a sheet assembly with a large sheet thickness ratio including a high strength steel sheet and by which a resistance spot welded joint having a superior tensile strength can be stably obtained. SOLUTION: The method of manufacturing a resistance spot welded joint is characterized in that, in manufacturing a resistance spot welded joint by joining a sheet assembly with a plurality of superimposed metallic sheets by resistance spot welding, a sheet assembly having a sheet thickness ratio of 5 or higher is used as an object and the resistance spot welding is configured to be welding of three steps comprising a first, a second and a third steps, that the welding of the second step is designed to have a higher pressurizing force, a lower or equal electric current, and a longer or equal energizing time compared with the welding of the first step, and that a higher pressurizing force and higher current energization than in the second step are repeated in the third step. COPYRIGHT: (C)2011,JPO&INPIT
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