Experimental and numerical study on three dissimilar and two similar sheets joined using resistance spot welding and clinching processes

Abstract

The automotive industry is increasingly adopting advanced techniques to meet the demanding performance requirements of structural components. Resistance Spot Welding (RSW) is a widely used method that joins materials using pressure and heat from an electric current. This study investigates RSW performance on a three sheet stack-up of 0.8 mm thick stainless steel 304, galvanized iron (GI), and mild steel 1006. Welding time was varied while keeping squeeze and hold times constant. Tensile testing and cross-sectional analysis showed that joint strength improved with welding time up to 700 ms, beyond which strength declined. The best performance was achieved with stainless steel on top, mild steel in the middle, and GI at the bottom. Future work will optimize additional parameters and analyse nugget formation. This research also explores a hybrid joining technique that combines RSW with mechanical clinching for mild steel 1006. The hybrid approach merges the rapid heating of RSW with the cold-forming interlock of clinching, enhancing joint strength, durability, and fatigue resistance. LS-DYNA simulations modelled both processes and were validated by experimental data. Tensile, shear, and fatigue tests confirmed that the hybrid method outperforms traditional techniques, offering better strength, a smaller heat-affected zone, and improved manufacturing efficiency ideal for automotive and structural applications.