Curie temperature effects on resistance spot welding

The effects of the Curie temperature on transport variables and nugget growth during resistance spot welding are investigated. The Curie temperature is the temperature, indicating that magnetic transformation below which a metal or alloy is ferromagnetic with high magnetic permeability, and above which it is paramagnetic with small magnetic permeability. The model accounts for electromagnetic force, heat generations and contact resistances at the faying surface and electrode-workpiece interfaces and bulk resistance in workpieces. Contact resistance includes constriction and film resistances, which are functions of hardness, temperature, electrode force and surface condition. The computed results show that the molten nugget on the faying surface initiates earlier with a high Curie temperature. High Curie temperature readily melts through the workpiece surface near the electrode edge. The present work can also be applied to interpret the contact problems encountered in various electronics and packaging technologies, etc.