Effect of tool rotational speed on microstructure and mechanical properties of friction stir welded AA6061-T6 alloy using brass interlayer

The tool rotational speed effect was studied on microstructure and mechanical properties of friction stir welded AA6061-T6 alloy using 0.5 mm thick brass interlayer. The transverse speed is kept constant as 30 mm/min and the tool rotational speed is varied as 800 rpm, 900 rpm and 1000 rpm. Optical microscope and scanning electron microscopes were used for microstructure analysis. The results revealed that the brass particles distributed uniformly in the weld nugget zone (WNZ). X-ray diffraction analysis (XRD) was carried out to analyse the phase formation between weld plate and brass interlayer. The results revealed that the formation of intermetallic phases such as Al4Cu9 and Al2Cu increased the tensile strength and hardness of the weld joint as compared to weld without interlayer. The maximum strength and hardness of the weld joint was achieved at a tool rotational speed of 800 rpm. (C) 2019 Elsevier Ltd. All rights reserved.