Fracture toughness of friction stir welded TA5 titanium alloy joint

Abstract Fracture toughness of friction stir welded titanium alloy joints was investigated using Compact tension (CT) toughness specimens. The fracture toughness slightly decreases to about 90% of the fracture toughness of base metal. The fracture surface was mainly ductile fracture mechanism with a large number of dimples. The crack propagation path was straight and mixed with intergranular and transgranular fracture. The stir zone of joint has a large number of fine ɑ grains with some dislocations. For texture, the stir zone has hard orientation {0002} 2 ¯ 0>, the directions of cylinder and plate thickness are parallel. The reduction of fracture toughness in the stir zone is mainly related to microstructure and texture.