热盐腐蚀环境对TC11钛合金高温寿命影响规律试验研究

目的 针对发动机钛合金部件在热盐环境与工作载荷下的寿命衰减问题，开展TC11钛合金热盐腐蚀疲劳与应力腐蚀试验，研究腐蚀环境下TC11的高温寿命衰减规律与失效机理。方法 利用喷盐法制备TC11钛合金试验件，研究不同温度与应力水平对TC11腐蚀疲劳以及应力腐蚀的影响规律。利用SEM等观测手段，开展腐蚀疲劳以及应力腐蚀试样断口与表面的形貌分析，分析腐蚀环境下的失效机理。结果 热盐腐蚀环境导致TC11的寿命显著降低，对比450 ℃下无腐蚀寿命，腐蚀疲劳寿命下降了2个数量级，应力腐蚀寿命下降到不足1%，且分散性较大。观察腐蚀疲劳和应力腐蚀的试样可以发现，表面有明显的腐蚀坑，腐蚀坑底发现裂纹。结论 热盐环境下，TC11腐蚀疲劳寿命和应力腐蚀寿命都会明显下降。由于腐蚀导致钛合金试样表面产生许多腐蚀坑，在腐蚀坑局部形成近似缺口，缺口部位的应力集中是导致腐蚀疲劳寿命衰减的重要因素。腐蚀疲劳的寿命低于Kt=1的无腐蚀疲劳寿命，但是要大于Kt=3的无腐蚀疲劳寿命。

Effect of Hot Salt Corrosion Environment on High Temperature Life of TC11 Titanium Alloy

The work aims to conduct hot salt corrosion fatigue and stress corrosion tests of TC11 titanium alloy to investigate the high temperature life decay characteristic and failure mechanism of TC11 titanium alloy components in engines under corrosion environment and working load. The TC11 titanium alloy samples was prepared by salt spray method to investigate the effects of different temperature and stress levels on corrosion fatigue and stress corrosion of TC11. The fracture and surface morphology of corrosion fatigue and stress corrosion samples and the failure mechanism were analyzed by SEM and other observation means. Hot salt corrosion environment reduced the life of TC11 titanium alloy, the corrosion fatigue life dropped by two orders of magnitude and the stress corrosion life was less than 1%, compared with the non-corrosion life, and the dispersion was relatively large. By observing the corrosion fatigue and stress corrosion samples, it could be found that there were obvious corrosion pits on the surface and cracks on the bottom of the corrosion pits. The hot salt corrosion fatigue life and hot salt stress corrosion life of TC11 titanium alloy in hot salt environment decrease obviously. Many pits on the surface of titanium alloy samples caused by corrosion form approximatively notches. The stress concentration at the notch is an important factor leading to the decay of corrosion fatigue life. The corrosion fatigue life is lower than the non-corrosion fatigue life of Kt=1 but greater than that of Kt=3.