Joinability of aluminium alloy and mild steel sheets by self piercing rivet

The joinability of aluminium alloy and mild steel sheets using a self piercing rivet is evaluated by a finite element simulation and experiment. The self piercing riveting has potential as a replacement for spot resistance welding generally used for steel sheets, because it is not easy to apply resistance welding to joining of aluminium and steel sheets which have very different melting points. Defects in the riveting are categorized into the penetration through the lower sheet, the necking of the lower sheet and the separation of sheets to obtain optimum joining conditions. The penetration, necking and separation are caused by the small total thickness, the small thickness of lower sheet and the large total thickness, respectively. The joinability for the combination of the upper sheet of steel and the lower sheet of aluminium is higher than that of the reverse combination.