K417G低压涡轮转子叶片振动疲劳断裂特征研究

对振动试验开裂的101件发动机低压涡轮转子叶片的裂纹形态、分布、裂纹断口等进行研究。结果表明:所有叶片裂纹均为横向裂纹，其中大部分叶片源区未见缺陷，裂纹位置主要集中在叶根附近进气边前缘或排气边尾缘位置，少数叶片裂纹萌生于疏松，位置随机分布；所有叶片断口均出现3个区域，即源区、沿{111}滑移面扩展的第Ⅰ阶段扩展区和叶片径向垂直的第Ⅱ阶段扩展区；源区主要为单疲劳源，第Ⅰ阶段扩展区发展充分，宏观上可见与叶片径向大致呈45°的反光小平面，微观上断口可见河流花样、滑移台阶和锯齿状断面等特征，第Ⅱ阶段扩展区断面平整，微观上可见间距不足1 μm的细密疲劳条带。

Vibration Fatigue Fracture Characteristics of K417G Low Pressure Turbine Rotor Blades

The morphology and distribution of cracks and characteristics of fracture surface of 101 low-pressure turbine blades cracking during vibration test were studied. The results show that the cracks of all the blades are transverse cracks, most of which have no defects at the source areas. The cracks are mainly located at the leading edge of the intake side or the trailing edge of the exhaust side near the blade root. A small fraction of the cracks originated from loose defects, and were randomly distributed. The facture surfaces of the blades all have three regions: the source region, the first-stage extending region along the {111} slip plane and the second-stage extending region perpendicular to the blade radial direction. The source areas are mainly single fatigue source. In the first stage, the expansion area is fully developed. On the macro level, there are reflective small planes roughly 45° from the radial direction of the blade. On the micro level, the fracture surface can be seen to have river pattern, sliding steps and zigzag section. In the second stage, the section of the expansion area is flat. On the micro level, there are fine fatigue stripes with the spacing of less than 1 μm.