Resistance spot welding method for Al-Mg based alloy sheet

摘要

PURPOSE:To obtain an electrode service life same as a plated steel sheet by making the thickness of an oxide film of the spot welding and joining part surface into a specified value and making the electrode pressurizing force into a specified value in performing resistance spot welding on plural Al-Mg-base alloy sheets. CONSTITUTION:The plural Al-Mg (5-9wt.%) - base alloy sheets whose thinnest sheet has 0.7-1.2mm thickness are superposed on each other and subjected to resistance spot welding and joined to each other with a welding current of 18000-36000A and at the weld time of 3-15 cycle. The thickness of the oxide film of the spot welding and joining part surface of these alloy sheets is regulated to 50-250 angstrom at least. The electrode pressurizing force of a welding machine is regulated to 350-450kgf. Consequently, the sufficient nugget diameter and the electrode service life same as the plated steel sheets more than 3000 points are obtained and it can greatly contribute to improvement of resistance spot welding of aluminizing of automobiles.