SEAM WELDING METHOD FOR STEEL SHEET WITH AL BASED PLATING

PROBLEM TO BE SOLVED: To weld a plated steel sheet to be welded at low cost with a simple mechanism by welding in a state where an iron-based conductive magnetic powder is adhered preliminarily to the surface of a plated steel sheet to be pressurized by an electrode wheel. SOLUTION: Plated steel sheets 2, 2a are welded with electrode wheels 3, 3a. These sheets 2, 2a are coated with magnetic powder slurry 5, 5a from nozzles 4, 4a provided before the electrode wheels 3, 3a; the sheets 2, 2a are welded before the liquid of the slurry 5, 5a evaporates. The slurry 5, 5a, welded to the plated steel sheets 2, 2a, passes into a sintered film 6, 6a. Fe is easy to diffuse in Al but hard in Cu. Therefore, energized with an iron based material interposed between the steel based electrode wheel 3, 3a and the Al based plated steel sheet, the iron based material is welded to the Al based plated steel sheet 2, 2a, but not to the electrode wheel 3, 3a. Wide adhesion of iron powder also allows attraction before the pressurizing part of the electrode wheels 3, 3a, on account of a magnetic field generated by a welding current. The inexpensive and ferromagnetic iron powder is desirable as an iron based electric conductor.