Effect of materials position on friction stir lap welding of Al to Cu

Friction stir welding has been successfully used to weld the dissimilar metals. A few investigations have been carried out on the friction stir lap welding of Al to Cu, but the basic issue of how the position of the metals would affect the joint strength is still not resolved. In the present study, the 7070 Al and the commercially pure copper are lap joined using friction stir lap welding technology. Two test cases are considered. The distinction refers to the position of Al with respect to Cu. Microstructural analyses are carried out to gain intermetallic compounds and some microcracks. The effect of position of materials on the heat generation is investigated and justified through the temperature measurements. Mechanical properties of each sample are characterized using both shear and hardness tests. The results reveal that the maximum fracture load of the joint is obtained when Al is placed on the top of Cu.