腐蚀环境对TC21钛合金疲劳行为的影响

基于飞机零部件在服役过程中因腐蚀导致疲劳断裂的问题,采用疲劳试验机、扫描电子显微镜对TC21钛合金在两种腐蚀环境以及室温空气环境下的疲劳进行了研究。结果表明,相同环境下随着应力降低,合金晶体内部位错累计能量速率减缓,合金疲劳寿命增加。同等应力条件下,3.5%NaCl水溶液环境下合金疲劳寿命最低,油箱积水环境下次之,室温空气环境下合金疲劳寿命最高。当应力较低时,差异更为显著。腐蚀环境下试样疲劳寿命较低,主要原因在于合金与溶液中离子发生反应形成大量腐蚀产物,促进裂纹萌生、加速裂纹扩展。

Effect of Corrosive Environment on Fatigue Behavior of TC21 Titanium Alloy

Based on the fatigue fracture caused by corrosion of aircraft parts during service, the fatigue of TC21 titanium alloy in two corrosive environments and room temperature air environment was studied by fatigue testing machine and scanning electron microscope. The results show that the cumulative energy rate of the internal dislocations of the alloy crystals slows down and the fatigue life of the alloy increases with the decrease of stress in the same environment. Under the same stress condition, the alloy has the lowest fatigue life under the environment of 3.5% NaCl aqueous solution, and the tank water storage environment is next. The fatigue life of the alloy is the highest under room temperature air environment. When the stress is low, the difference is more significant. The fatigue life of the sample is low under corrosive environment. The main reason is that the alloy reacts with ions in the solution to form a large number of corrosion products, which promotes crack initiation and accelerates crack growth.