A metallurgical study of spot weld growth on mild steel with 1mm and 2mm thicknesses

Abstract

Resistance Spot Welding (RSW) is an important welding technology for joining two or more metals in various manufacturing industries. For instance, to date a car may contain an average of 3000-4000 spot weld joints and the nuggets’ joints are very important between metal sheets to ensure the aging factor of mechanical assemblies. As such the growths of spot welds create significance and it is determined by its’ main controlling parameters such as: current, weld time and force. However factors such as electrode deformation, dissimilar materials, materials with different thicknesses and corrosions are also affect weld growth. This study was conducted to look into the effects of different thickness (1 mm and 2 mm) on weld nugget growth of mild steel. The tensile test and hardness test have been carried out to characterise the formation of weld nugget growth for different weld schedules. The results of the experiments showed that the growth of spot weld nuggets was affected by different thicknesses. The microstructures of weld nuggets have also shown distinguishable differences in weld growth for the both 1 mm and 2 mm thicknesses. The results have shown difference in yield strength as well, for the same welding schedules. This was happened due to the difference of resistive path of two thicknesses.