Characteristics of Dwell Fatigue Failures and Method for Assessing the Dwell Sensitivity of Titanium Alloys

Titanium alloys have come up against dwell fatigue failures during service in the aircraft engine. In contrast to normal continuous cycling, dwell fatigue is manifested by a significant reduction in fatigue life and has distinct failure characteristics. Through the systematic experimental research, where research objects covered from highly susceptible to unsusceptible titanium alloys, the characteristics of dwell fatigue failures have been summarized from three aspects, including the fatigue fracture, secondary crack and strain accumulation. According to the summarized failure characteristics, the method for identifying the dwell fatigue failure and assessing the dwell sensitivity has been put forward. Key words: titanium alloy; dwell fatigue; dwell sensitivity; fracture characteristic; failure analysis