固溶时效对Ti-6Al-4V合金组织及性能的影响

Effect of Solution and Aging on Microstructure and Properties of Ti-6Al-4V Alloy

为明确固溶温度及冷却方式对Ti-6Al-4V合金组织与性能的影响,通过不同热处理工艺对合金进行固溶时效热处理。利用金相显微镜观察处理后试样的显微组织,并对试样进行了室温拉伸及硬度测试。结果表明:当固溶温度不超过合金相变温度时所得组织由初生α相(αp)和β转变组织(βt)构成,且固溶温度与相变温度相差越小,βt体积分数越大,合金硬度和强度升高而延伸率降低;固溶温度在相变温度以上时所得组织为片状组织,合金的硬度、强度和延伸率均显著恶化;随冷却速度加快合金晶粒尺寸逐渐缩小,硬度和强度提升而延伸率降低。

To clarify the effect of solution temperature and cooling mode on the microstructure and properties of Ti-6 Al-4 V alloy, different heat treatment processes are performed on the alloy. The microstructures of the samples are received by a metallographic microscope, the tensile and hardness tests are carried out at the room temperature. The results show that when the solution temperature is lower than the phase transformation temperature, the received microstructure is composed of primary α phase(αp) and transformed β matrix(βt). And the smaller the difference between the solution temperature and the phase transformation temperature, the larger the volume fraction of βt. Consequently, the hardness and strength are enhanced, yet the ductility decreases. The microstructure turns into lamellar structure when the solution temperature surpasses the β-transus temperature, resulting in the deterioration of the hardness, strength and ductility. Furthermore, the grain size of the alloy gradually decreases with the increase of cooling rate, which results in the increasing of the hardness and strength, the decreasing of the ductility.