外物损伤对TC4钛合金的高周疲劳强度的影响

摘要

为了研究外物损伤对航空发动机叶片疲劳性能的影响规律,将直径为3、4 mm的钢珠利用空气炮加速到约300 m/s对TC4合金平板试样进行外物损伤试验,利用3维体式显微镜和扫描电子显微镜(SEM)分别观察外物损伤的宏观特征和微观特征.结果表明:在随后的高周疲劳试验中外物损伤容易诱发疲劳裂纹的萌生,且试样的疲劳强度随损伤深度的增加而降低;疲劳源一般位于损伤区域的表面位置,因为试样在冲击过程中在损伤区域形成了微观裂纹和缺口.%In order to study the influence of foreign object damage on aeroengine blades fatigue performance, Foreign Object Damage (FOD) was simulated by the 3 and 4 mm diameters hardened steel spheres onto the flank of the TC4 plate specimens. A light gas gun was used to fire the projectiles and the values of impact velocity were set 300 m/s. The macroscopical and microscopical characteristics of specimen damage were respectively observed by three-dimensional digital microscope and scanning electron microscope (SEM). Results show that the effect of FOD can easily induce preferred sites for the premature initiation of fatigue cracks on subsequent cycling, and the fatigue strength decreases with the serious depth of damage. It is also found that the fatigue source normally locates in the surface of damage area, and initiates from the micro cracks or micro notches caused due to the impact.