Microstructure evolution of linear friction welded TC6 joint

Linear friction welding (LFW) was carried out on the TC6 titanium alloy using a LFW machine (type XMH-160). Microstructural features and forming process of the weld zone, thermo-mechanically affected zone (TMAZ) and flash were analyzed. The results show that the tensile strength of the LWFed TC6 joint is not lower than base metal, and microhardness corresponds to microstructure features of different zones. Recovery and recrystallization occurr in the weld zone, and the major microstructure are metastable β, martensite and secondary α which forms during rapid thermal cycle and deeply deformation. Meanwhile, a small amount of deformed primary α was reserved. Recrystallization only occurs in part of the metal in the TMAZ, where flow lines consist of deformed α and β existed.