Linear friction welding of a beta titanium alloy: experimental investigations on microstructure evolution and mechanical properties

Linear friction welding was used to join Ti–3Al–8V–6Cr–4Mo–4Zr alloy under different pressures, and the microstructure, texture evolution and mechanical properties of the joint were investigated. Results show that the incomplete continuous dynamic recrystallisation (CDRX) occurs during welding, which refines the grains and produces a large number of subgrains in the thermo-mechanically affected zone (TMAZ) and weld centre zone (WCZ). At a higher friction pressure, the width of the WCZ becomes narrower, with the decrease of grain size and the increase of recrystallisation degree. In addition, the texture in the WCZ has changed from {112}<111> to {110}<111>, while the texture in the TMAZ remains at {110}<112>. The tensile properties of the two joints are similar to the base metal (BM), and the microhardness in WCZ and TMAZ are also close to that in BM due to the incomplete CDRX and the decrease of alpha phase.