TC4 Titanium Alloy Fatigue Property at High Temperature and High-Low Temperature Field
The work aims to study fatigue property of TC4 titanium alloy at high temperature and high-low temperature field(25～390℃).The difference of fatigue property at two different conditions and the mechanism of temperature effect were studied by high temperature fatigue test,the high-low temperature fatigue test and fractographic analysis.As temperature rose from 25℃to 390℃,the fatigue property of TC4 titanium alloy was reduced in the short life regime(N<106 cycles).The fa-tigue property showed nonlinear variation tendency in the long life regime(N>106 cycles).The fatigue property was enhanced firstly and then showed a degradation tendency.It was observed that oxidation became more and more obvious with the increase of temperature and for the longer test duration as shown in fractographic analysis.At the same stress level,the fatigue life of the high-low temperature fatigue test was longer than that at the highest temperature,and shorter than that at the lowest temperature.When the environment temperature is between 25℃and 390℃,the fatigue property of TC4 titanium is affected by both tem-perature and oxidation at the same time.The fatigue property is degraded with the increase of temperature.On the other hand,the protective oxidation film formed in the high temperature environment can improve fatigue property.The fatigue life at the high-low temperature field can be predicted by a stress-life curve at equivalent temperature.The model has a good predictive precision.
high temperaturehigh-low temperatureTC4titanium alloyfatigue propertyoxidation
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