TC4钛合金外物损伤后疲劳行为研究

针对发动机一级盘用材料冲击损伤后的高周疲劳性能需求，对TC4钛合金在外物损伤后的疲劳行为开展研究。采用空气炮法制备含3种不同程度外物损伤的TC4钛合金试样并统计损伤尺寸，对无冲击损伤和含外物损伤的试样进行疲劳试验，获得S-N曲线，观察疲劳裂纹萌生位置。结果表明:更快的冲击速度和更大的弹丸直径会形成更大的FOD损伤；外物冲击改变裂纹萌生位置；通过损伤尺寸的统计与疲劳性能的对比发现，试样宽度方向的损伤尺寸是影响疲劳寿命的最主要因素。

Fatigue Behavior of TC4 Titanium Alloy After Foreign Object Damage

In order to meet the requirements of high cycle fatigue performance after impact damage of materials used in engine primary disk, the fatigue behavior of TC4 titanium alloy after external material damage was studied. TC4 titanium alloy samples containing three kinds of foreign object damage were prepared by air cannon method and the damage size was calculated. Fatigue tests were carried out on the samples without impact damage and with foreign object damage. The S-N curve was obtained and the initiation position of fatigue crack was observed. The results show that higher impact velocity and larger projectile diameter lead to larger FOD damage. The location of crack initiation is changed by external impact. By comparing the damage size statistics with the fatigue performance, it is found that the damage size in the width direction is the most important factor affecting the fatigue life.