A near α titanium alloy (Ti6242) was joined by the linear friction welding technique followed by the post- welded heat treatment (PWHT). Both joints in as-welded and PWHTed conditions were characterized in a multi-scale manner to investigate the evolution of microstructure and establish the relationship between the microstructure and mechanical properties of the joints. Results show that both joints fail in the base material, while the PWHTed joints have large hardness enhancement in the welding line (WL) and thermo-mechanically affected zone (TMAZ). After heat treatment, the cluster of the flakier α phase is formed inside the equiaxed grains in WL, while the martensite phase in TMAZ is decomposed into the (α+β) phase, both of which can improve the hardness of the joint.