Investigating the effect of material properties on simulation of Mg alloy resistance spot welding process

The main purpose of this study is investigation the effects of mechanical and thermal properties on accuracy of finite element model in resistance spot welding of AZ61 Mg alloy. In this study temperature dependent thermo-mechanical properties of AZ61 Magnesium alloy sheets and also thermal and electrical contact conductance (TCC and ECC) have been experimentally determined to use in a coupled electrical-thermal-mechanical finite element (FE) model in order to predict distribution of residual stresses and nugget size in resistance spot welding (RSW) process. The thermo-mechanical properties, TCC and ECC have been employed in FE model as: constant, linear and temperature dependent to investigate the effects of these parameters on accuracy of the FE model. In addition, different welding parameters such as welding current, welding time and electrode force have been used in FE model to achieve different nugget size. The results showed that thermal conductivity, electrical resistivity and ECC have significant effect on nugget size and also yield stress and elastic modulus have important influence on distribution of residual stresses. Therefore, the thermal conductivity, electrical resistivity and ECC for prediction of nugget size and also the yield stress and young modulus for prediction of distribution of residual stresses should be assumed to be temperature dependent and linear, respectively. Moreover, remaining thermo-mechanical properties can be taken as constant.