气膜孔倾角角度对单晶高温合金疲劳性能的影响

Effects of Slant Angle of Film Hole on Fatigue Properties of Single Crystal Superalloy

关键词:  气膜孔  倾角角度  疲劳寿命  晶体塑性理论  单晶高温合金

Key words:  Film hole  Slant angle  Fatigue life  Crystal plasticity theory  Single crystal superalloy

摘要:

为了研究气膜孔倾角角度对单晶高温合金疲劳性能的影响，设计倾角30°，45°，90°的14孔平板试样进行了同等应力水平下的高温疲劳试验，并对断裂后失效试件进行断口分析。基于晶体塑性理论，对不同倾角气膜孔平板件进行数值计算，分析孔边局部应力及损伤演化。结果表明，气膜孔倾角角度对疲劳性能影响显著，疲劳寿命90°>30°>45°，且45°倾角气膜孔孔边裂纹数明显多于其他两种。数值模拟显示，90°孔每个循环累积的应变相对较小，30°斜孔次之，45°斜孔最大，且 45°斜孔和 30°斜孔的棘轮应变累积速率明显高于直孔，30°斜孔的损伤和直孔的损伤较为接近，45°斜孔的损伤最大，数值分析与实验结果相一致。

Abstract:

In order to study the effects of the slant angle of film hole on the fatigue properties of single crystal superalloy， high temperature fatigue tests were carried out on 14 hole flat specimens with designed angle of 30°， 45?， 90?，respectively， under the same stress level， and the fracture analysis was carried out on the failure specimens. Based on the theory of crystal plasticity， numerical calculation was carried out for the flat plate with different slant angles of film holes， and the local stress and damage evolution of the hole edge were analyzed. The results show that the slant angle of the holes has a significant effect on the fatigue performance， and the order of the fatigue life is 90°>30°>45°. The number of cracks on the holes with the slant angle of 45° is significantly more than the other two type specimens. The numerical simulation shows that the accumulated strain of each cycle of 90° hole is relatively small， followed by 30° slant angle specimen and 45° slant angle specimen. The ratchet strain accumulation rates of 45° slant angle specimen and 30° slant angle specimen，respectively， are significantly higher than that of straight hole. The damage of 30° slant angle specimen is close to that of straight hole， and the damage of 45° skew hole is the largest. The calculation results are consistent with the experimental results.