Cycle fatigue properties of TA15 titanium alloy linear friction welded joint

The high cycle fatigue properties and fracture features of TA15 titanium alloy and Linear Friction Welded (LFW) joint were investigated. The results show that fatigue strength of bi-model structure of TA15 base metal is lower than acicular structure of welded joint，and with the stress increasing，the fatigue property gap between welded joint microstructure and base metal microstructure gradually decreasing. The fatigue limit of LFW joint acicular structure (463 MPa) is higher than that of base metal bi-modal structure (423 MPa) in the high cycle. Fracture analysis results show that the fracture of TA15 base metal is smooth and second cracks are less than those of welded joint in extended area. Second cracks reduced the crack growth rate, which shows that the fatigue property of acicular structure is superior to that of bi-modal structure.