退火温度对激光熔化沉积TC31高温钛合金组织与性能的影响

为改善激光熔化沉积TC31高温钛合金力学性能,本文通过光学显微镜、SEM、TEM和力学性能测试的方法研究了退火温度对合金中组织演化行为的影响,及其与合金室温和650 ℃高温力学性能的关系。结果表明:组织中初生α相含量随着退火温度升高而降低,其溶解主要发生在950 ℃以上,980 ℃退火后含量仅为29%。当退火温度超过930 ℃时,初生α相片层宽度明显增加。随着退火温度升高,α/β界面处析出的(Ti, Zr)₆Si₃相尺寸增加,且进入α相片层内部。合金在800~1 000 ℃退火时,合金室温拉伸屈服强度随退火温度升高趋于降低。受相界面析出的硅化物聚合长大及α相片层尺寸增加等因素影响,合金高温屈服强度随退火温度升高先降低后增加。合金经过1 000 ℃退火后,呈现良好的高温性能,其650 ℃下抗拉强度达657 MPa、屈服强度约为466 MPa、延伸率27%。

Effect of annealing temperature on the microstructure and mechanical properties of laser melting deposited TC31 high temperature titanium alloy

In order to improve the mechanical properties of laser melting deposition (LMD) TC31 high-temperature titanium alloy, the influence of annealing temperature on the microstructure evolution and mechanical properties was studied by using OM, SEM, TEM and mechanical property tests. The results revealed that the primary α phase content decreases with the increase in annealing temperature during single-stage annealing. The dissolution mainly occurs above 950 ℃, and then its content is only 29% at 980 ℃ after annealing. When the annealing temperatures exceeds 930 ℃, the width of the primary α phase dendrites significantly increases. As the annealing temperature increases, the size of the (Ti, Zr)₆Si₃ phase precipitated at the α/β interface increases and enters the interior of the α lamellae. The room-temperature yield strength tends to decrease with increasing annealing temperature when the alloy is annealed at 800 ℃ to 1 000 ℃. Due to the factors such as the growth of aggregated precipitates at phase interfaces and the increase in the size of α phase dendrites, the high-temperature yield strength of the alloy firstly decreases and then increases with increasing annealing temperature during annealing. The alloy exhibits excellent high-temperature mechanical properties after annealing at 1 000 ℃, with a tensile strength of 657 MPa, yield strength of approximately 466 MPa, and an elongation of 27% at 650 ℃.