Simultaneous Effect of Tool Rotation and Dwell Time on Quality of Dissimilar AA5052-Copper Joints Fabricated by Friction Stir Spot Welding

Abstract

In the present study, lap joints of dissimilar 5052 aluminum alloy and pure copper were fabricated by friction stir spot welding process. The work was aimed to find effect of parameters such as tool rotary speed (1000, 1400 and 2000 RPM) and dwell time (5, 10 and 15s) on microstructure and strength properties of lap joints. Also, statistical models of the quality characteristics were developed to understand which interaction has dominant effect on quality characteristics. Research findings showed that to obtain sound joints with high lap shear strength tool rotary speed of 2000 rpm and dwell time of 5s should be selected. It provides sufficient heat input and prevents the excessive material softening. On the other hand, to achieve maximum hardness, 2000 rpm tool rotary speed should be chosen to provide enough heat for formation of intermetallic compound and 10s dwell time should be used prevent enough time for microstructure refining. Moreover, from the statistical analyses, it was found that dwell time and tool speed are the significant factor for lap shear strength and hardness, respectively. In order to attain simultaneous maximum strength and hardness, tool speed of 2000 rpm and dwell time of 8 s should be used. In such condition lap shear strength of 1755 N and hardness of 77 V are achieved with desirability of 85%.