真空高温退火对锻态Ti-6Al-4V合金显微组织与超塑性性能的影响

Effect of High-Temperature Vacuum Annealing on Microstructure and Superplasticity of Forged Ti-6Al-4V Alloy

退火处理是改善钛合金显微组织,提高力学性能及超塑成形性能的一种重要工艺。使用真空退火炉在850℃-950℃温度区间内对锻态Ti-6Al-4V合金的进行了高温退火处理,研究了退火态Ti-6Al-4V合金微观组织演变及其在温度为900℃,应变速率为0.01 s;时的超塑拉伸性能。结果表明,锻态Ti-6Al-4V合金的初生α晶粒尺寸随真空退火温度的升高而减小,β相比例随真空退火温度升高而增大。当真空退火温度为910℃时,Ti-6Al-4V合金的晶粒尺寸和α相与β相分布较为均匀,其超塑拉伸试验结果表明,该合金表现出最佳的超塑拉伸性能,其拉伸延伸率达到785%,峰值应力仅为26.8 MPa。

Annealing treatment is an important technology to improve the microstructure, mechanical properties, and superplastic properties of titanium alloy. Forged Ti-6Al-4V alloy was annealed at the temperature of 850℃-950℃ in a vacuum annealing furnace, and the superplastic tensile tests of Ti-6Al-4V alloy were conducted at a temperature of 900℃ and strain rate of 0.01 s;. The effect of high-temperature vacuum annealing on microstructure evolution and superplasticity of Ti-6Al-4V alloy was investigated. The results show that the primary α grain size decreases with the increase of vacuum annealing temperature, and the proportion of β phase increases with the vacuum annealing temperature. The distribution of grain size and phase of α and β is relatively uniform in the sample annealed at 910℃, which exhibits the best superplastic tensile performance with the maximum tensile elongation of 785% and minimum peak stress of 26.8 MPa.