Investigation on Metallurgical Structure and Mechanical Properties of Dissimilar Al 2024/Cu FSW T-joints

Abstract

In this research, T-joining of AA2024-T4 and commercially pure copper were performed successfully using friction stir welding. Effect of welding parameters on metallurgical and mechanical characteristics of the joints was studied. For this purpose, tensile strength, microhardness, and macro- and microstructures of the joints were investigated. Also, the fracture surfaces were examined using XRD and SEM. The best results were obtained for the 1130 rpm rotation speed (ω) and 12 mm/min travel speed (v), with the UTS of 156 MPa (~70% of Cu strength). The microhardness test showed that TMAZ and base metal of Al side had the maximum hardness amounts (148 and 155 HV, respectively). Generally, increase in the ω2/v ratio caused the nugget zone and HAZ grain size to increase. The results revealed the formation of Al2Cu and Al4Cu9 intermetallic compounds in the border zone of the joints. The fractography results showed the occurrence of cleavage fracture in all the samples.