Effect of Electrode Tip Shape on Strength and Microstructure in Resistance Spot Welding of AZ31B Magnesium Alloy
The effect of electrode tip shape on strength and microstructure of weld spot in resistance spot welding of AZ31B Mg alloy was studied by experimental investigations. The results show that electrode tip shape which leads to the difference of contact area,current density and temperature at the sheet/ sheet interface have dominant effect on tensile shear strength and microstructure of weld spot. It was found that weld spot had lower strength and smaller deformation by the spherical-flat electrodes compared to the double truncated cone electrodes, and better property of weld joints can be obtained by truncated cone electrodes. At the same time defects, fracture feature and formation causes were analyzed in order to improve the quality of magnesium alloy spot welding joints.