热处理工艺对TC11钛合金组织及性能的影响

Effects of Heat Treatment Conditions on Microstructure and Mechanical Properties of TC11 Titanium Alloy

研究了热处理温度和冷却方式对初始组织为等轴组织的TC11钛合金显微组织及力学性能的影响。结果表明,对于TC11钛合金,在空冷条件下,随热处理温度的升高,等轴α相含量逐渐减少;当热处理温度超过980℃,合金开始发生组织形态的改变,由初始的等轴态转变为α＋β双态组织,随温度的继续升高,等轴组织完全转变成片层状组织;热处理温度在980℃以上时,随冷却速度的增加,β转变组织的片层厚度逐渐减小,冷却速度较快时（水冷）,形成淬火马氏体。拉伸试验研究表明,热处理温度为980~1020℃,空冷（或油冷）条件下,得到的组织具有较好的高温综合力学性能,其中热处理温度在980~1000℃之间得到的组织由于等轴α相含量约为50%,具有最佳的力学性能。

The effects of heat treatment temperature and cooling rate on microstructure and mechanical properties of TC11 alloy with equiaxed primary microstructure were investigated. The results show that with increase of temperature at air cooling condition, α phase volume fraction of TC11 titanium alloy decreases;when temperature exceeds 980 ℃, microstructure morphology of the alloy is transformed from equiaxed pattern to bimodal and further to widmanstatten and lamellar microstructure. With increase of cooling rate above 980 ℃, the transformed lamellar microstructure decreases and changes to martensite when cooling rate is high enough （water cooling）. The best mechanical properties of TC11 alloy are achieved after heat treating at 980 - 1020 ℃ by air cooling or oil cooling, and optimized mechanical property from bimodal microstructure with more than 50% equiaxed α phase can be got with heat treatment temperature between 980 ℃ and 1000 ℃.