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对经不同温度加热随后空冷的ＴＣ４钛合金在－１９６～３５０℃范围内进行了外约束型热疲劳试验。结果表明：经单相区加热的合金，其热疲劳裂纹易于沿原β相晶界处萌生，以穿晶的方式扩展，对热疲劳裂纹萌生抗力较低。而经９５０℃加热的合金，其热疲劳裂纹易于沿初生α相与基体（条形的α＋β相）的界面处萌生，裂纹易于切过条形的α＋β相扩展，其热疲劳裂纹萌生抗力最高。经９００℃加热的合金，其热疲劳裂纹易于沿初生α相与基体的界面处萌生并沿其扩展，合金的热疲劳裂纹萌生抗力也较低
The TC4 titanium alloy heated at different temperatures and then air-cooled was subjected to the outer-constraint thermal fatigue test at -196 ~ 350 ℃. The results show that the thermal fatigue cracking of the alloy heated by the single phase zone is easy to occur along the grain boundary of the original β phase and expands by means of transgranular cracking. The thermal fatigue crack initiation resistance is low. However, the thermal fatigue cracks easily occur along the interface between the primary α phase and the matrix (strip-like α + β phase) at 950 ℃, and the cracks tend to cut through the strip-shaped α + β phase. The thermal fatigue crack initiation resistance is the highest. The thermal fatigue cracking of the alloy heated at 900 ℃ tends to initiate along the interface of the primary α phase and the matrix and the thermal fatigue crack initiation resistance of the alloy is also lower