RESISTANCE WELDING METHOD OF HIGH TENSILE STEEL SHEET

摘要

PROBLEM TO BE SOLVED: To provide a resistance welding method that suppresses generation of expulsion together with initial expulsion and expands a nugget diameter, in lap resistance welding of a high tensile steel sheet.

SOLUTION: A resistance welding method of a high tensile steel sheet is provided in which at least two steel sheets including at least one high tensile steel sheet are superimposed and resistance-welded. The method includes: a first step in which a nugget 3 is formed having a nugget diameter of 3√t to 5√t (t is the thickness (mm) of one steel sheet having a smaller thickness of the two steel sheets) by energization to at least the two steel sheets; a second step in which a welding current is reduced after the first step; and a third step in which a welding current greater than that of the first step is energized after the second step and the nugget 3 is expanded by imparting a pressurizing force of 110-150% of the pressurizing force in the first step.

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