Friction stir welding (FSW) has been widely applied to metals with moderate melting points, primarily aluminum alloys. Recently, tool materials that withstand the high stresses and temperatures necessary for FSW of materials with high melting point have been developed. In the present study, polycrystalline cubic boron nitride (PCBN) tool was used for partially penetrated FSW of Inconel Alloy 600, and a defect-free weld was successfully produced. Microstructural characteristics, and mechanical and corrosion properties of the weld are succinctly reported in this paper.
Inconel Alloy 600 is an Ni-Cr-Fe alloy having excellent mechanical properties and corrosion resistance at high temperatures. Taking advantages of these positive factors, this alloy has been used in many applications, such as heat exchanger tube in nuclear power plant (Kim and Moon, 2004; Lim et al., 2001). In many commercial applications, welding is inevitable. However, fusion welding processes often result in hot-cracking in fusion zone due to segregation of alloying elements during solidification. To alleviate the problem, careful control of the weld metal composition and temperature are often required during welding.
Friction stir welding (FSW) is a solid-state joining process and patented by The Welding Institute (TWI) in UK in 1991 (Dawes and Thomas, 1996). Recently, several welding tools for high melting temperature materials, having high temperature strength and wear resistance, have been developed (Sorensen, 2004). The tool developments have enabled investigators to effectively study FSW of high melting temperature materials, including papers on FSW of carbon steels (Thomas et al., 1999; Lienert et al., 2003; Ozekcin et al., 2004), stainless steels (Reynolds et al., 2003; Okamoto et al., 2003; Park et al., 2003b; Park et al., 2004; Sato et al., 2005) and Ti alloys (Ramirez and Juhas, 2003) have been reported.
