Progress in friction stir welding of Ni alloys

In recent years, interest has been increasing in application of Nickel alloys in the oil industry. For subsea engineering, the possibility to weld high-strength materials in an effective manner is essential. Friction Stir Welding (FSW) is alternative to join several materials retaining their properties or even improving them. This fact is relevant for Corrosion-Resistant Alloys (CRA) used in deep-water exploitation of hydrocarbons. Publications up to now have focused on FSW of Inconel (R) series as alloy 600, 625, and 718. To provide a solid basis for development, this review discusses the crucial points for FSW. The tool materials are described, as well as the joint microstructure and properties achieved. Furthermore, the basics of the corrosion resistance and the early corrosion studies of FSW joints are presented. It is concluded that FSW is a promising process for Ni alloys, but depends on upcoming research regarding tool technology and corrosion investigations.