Friction-stir welding and processing of Ti-6Al-4V titanium alloy: A review

In this work, the current understanding and development of friction-stir welding and processing of Ti-6Al-4V alloy are briefly reviewed. The critical issues of these processes are addressed, including welding tool materials and design, tool wear, processing temperature, material flow, processing window and residual stresses. A particular emphasis is given to microstructural aspects and microstructure-properties relationship. Potential engineering applications are highlighted.