Study on High Temperature Fatigue Crack Propagation and Mechanical Behavior of TiAl Alloy

The aim of this study is to enrich the mechanical properties database of TiAl alloy due to the lack of crack propagation test data under negative stress ratio. Therefore, a central tensile specimen suitable for the negative stress ratio crack propagation test of TiAl alloy was designed. At the same time, a 1200 °C high temperature fatigue plate heating furnace was developed, and a test technique for measuring fatigue crack length by DC potential method was developed. The fatigue crack propagation data of TiAl alloy at 600 °C and 800 °C were successfully obtained by loading specimens by fatigue testing machine, combined with DC potential method. The experimental results show that the fatigue crack propagation rate of TiAl alloy increases with the increase of test temperature. At the same temperature and stress intensity factor amplitude, the increase of stress ratio also accelerates the fatigue crack propagation of TiAl alloy. The fracture morphology of TiAl alloy was further observed, showing typical cleavage characteristics.