外物损伤对不锈钢模拟叶片疲劳强度的影响研究

本文开展了1Cr15Ni4Mo3N不锈钢模拟真实前缘叶片的外物损伤(FOD)与高周疲劳(HCF)试验,旨在研究不锈钢叶片在承受外物损伤后的剩余疲劳强度。使用空气炮法对模拟叶片进行了FOD试验,结果表明损伤主要可分为半圆型、V型和撕裂型三类,且损伤深度随着钢珠直径、入射速度的增大而增大。基于步进法开展了FOD试样的HCF试验,试验结果表明FOD试样的振幅疲劳强度下降了70%以上,且随着损伤深度、入射速度的上升表现出明显的下降趋势。不同缺口类型之间存在差异,半圆型缺口疲劳强度较高,V型缺口稍低,撕裂型缺口最低。使用SEM观测了FOD缺口及断口微观特征,疲劳裂纹源区均位于缺口根部表面附近,说明高速冲击造成的材料丢失、剪切带与剪切韧窝等微观特征促使了疲劳裂纹的萌生。

Effects of Foreign Object Damage on Fatigue Strength of Stainless Steel Simulated Blades

Foreign object damage (FOD) and high cycle fatigue (HCF) tests were carried out for 1Cr15Ni4Mo3N stainless steel simulation blades to study the residual fatigue strength of specimens after FOD. FOD tests were performed by the air cannon system and the results show that the damage can be divided into three types: semicircle type, V type and tearing type. The damage depth increases with the enlargement of the steel ball diameter and the incident velocity. HCF tests of FODed samples were conducted by a step-loading method. The results show that the amplitude fatigue strength of FODed sample has decreased by more than 70%. It shows a significant downward trend with the increase of damage depth and incident speed. The fatigue strength of semicircle type notch is higher, while of V type notch is slightly lower, and of tearing type notch is the lowest. The micro characteristics of damage notches and fatigue fractures were observed by SEM. The fatigue source area is near the notch root, which indicates that the loss of material, shear bands and shear dimples caused by high-speed impact promote the initiation of fatigue crack.