Influence of Interlayer Material on Softening and Wear Behavior of Friction Stir Welded AA6061-T6 alloy

In this investigation, Zn and brass interlayers were used for friction stir welding (FSW) of AA6061-T6 and investigated the weld joint’s microstructure, mechanical, and wear behavior. From microstructural analysis, it was observed that Zn dissolved in Al matrix at FSW process temperature and formed a solid solution. Brass particles distributed uniformly throughout the stir zone (SZ) formed a composite-like structure and intermetallic compounds (IMCs) such as Al 2 Cu and Al 4 Cu 9 . The grain size obtained for weld without interlayer, with Zn and brass interlayer, was 5.6 µm, 3.6 µm, and 2.3 µm, respectively. Hardness in SZ improved with brass interlayer. Marginal strength was enhanced for weld with Zn interlayer, and better strength was obtained with brass interlayer due to reduced softening and formation of IMCs than for weld without interlayer. The surface hardening mechanism reduced the wear rate for weld with brass interlayer.