GIGACYCLE FATIGUE PROPERTIES OF A TURBINE ENGINE BLADE TITANIUM ALLOY TI811 AT ELEVATED TEMPERATURE

摘要

An ultrasonic fatigue testing system (20 KHz) equipped with induction heating attachment was employed to study the gigacycle fatigue properties of a turbine engine blade titanium alloy (Ti-8Al-1Mo-1V, named TA11 by Chinese Standard) at ambient temperature (20 ?C) and 300 ?C under fully reverse loading (stress ratio R=-1). With the increase of temperature, the stress-life curve types changed from continuous decline shape to duplex characteristic. Compared with room temperature, very high cycle fatigue (VHCF) strength of the titanium alloy decreased dramatically at high temperature. The interior initiations were only detected at ambient temperature. Fracture surfaces failed at 300 ?C showed specific features. Moreover, the mechanism of facet-induced fatigue crack initiation is activated at high temperature.