Experimental and finite element investigation of resistance spot welding of mild steel sheet covered aluminum alloy, AA 2017

Resistance spot welding (RSW) is one of the welding technologies that uses the force and heat generated by resistance to the flow of electricity to join metal surfaces. The goal of this research is to investigate the mechanical behavior of RSW,the welding parameters of sheet metal-covered aluminum spot-welded junctions, and finally to verify the micro-hardness of the weld structure. RSW process is a complicated operation that combines electrical, thermal, and mechanical processes. Moreover, serious complications are observed when the weld material is aluminum, because it is a very soft metal and difficult to weld as compared to other metals, Hence, we used mild steel as a cover on both sides and easily did the RSW. Aluminum (Al) thickness, cover sheet metal thickness, and overall welding time achieved relative impacts of 3.890%, 3.250%, and 84.390%, respectively. The percentage impacts of aluminum (Al) thickness, weld cover sheet metal thickness, and welding time in the deformation scenario are 1.171%, 8.731%, and 80.881%, respectively. The percentage impacts of aluminum thickness, cover sheet metal thickness, and welding time duration on temperature are 9.960%, 87.820%, and 1.660%, respectively. The thickness of the cover mild steel sheet is the second-most important factor, next to welding time. Validation results of the two critical weld constraints (welding temperature and welding time) agrees with the experimental results. In addition, the welding temperature response has a percent error of 10.620% due to materials characteristics and the impact of additional welding process constraints.