Fatigue strength and mechanism of Ti6242S titanium alloy with TiAlN coating deposited under various bias voltages

Fatigue strength and mechanism of Ti6242S titanium alloy with TiAlN coating deposited under various bias voltages were investigated. Fatigue strengths of the coated specimens deposited under higher bias voltages were significantly improved compared to uncoated specimen, where a fatigue crack nucleated in the subsurface. On the other hand, the coated specimens deposited under lower bias voltages exhibited degraded fatigue strength compared to uncoated specimen, where fatigue crack nucleated from the coated surface. The compressive residual stress induced in the coating layer was significantly increased with increasing bias voltage, which dominantly influence the fatigue behavior and fatigue mechanism of the coated specimen.