发动机涡轮叶片榫齿磨削裂纹原因分析

Analysis on the Formation of Grinding Cracks in Aero-Engine Turbine Blade Tenon

发动机涡轮叶片在榫齿磨削加工后,发现部分叶片榫齿加工表面存在线性荧光显示。采用扫描电镜和金相分析,比较叶片铸件在磨削前与磨削后榫齿部位显微组织的差异,结合叶片实际生产工艺,分析叶片榫齿磨削加工后裂纹的形成原因并提出相应的解决措施。结果表明,叶片榫齿荧光显示部位存在一定程度的显微缩松,弥散分布的孔洞在磨削应力的作用下沿剪切应力方向撕裂形成内部相互连通的孔道,从而引起线性荧光显示。适当地降低拉晶速度,延长抽拉时间,可以有效地减轻显微缩松的形成,从而避免了磨削后榫齿裂纹的产生。

The tenons of the turbine blades in aeroengine show linear fluorescent indication after grinding the tenons.The microstructures near the tenons before and after grinding was compared by optical microscopy and scanning electron microscopy(SEM).The origination for the cracks in blade tenon after griding was analyzed based on the production process of the blades,and the corresponding measures were proposed.The results indicate that there exists a certain degree of microporosity at the position indicated by fluorescence,and the dispersed holes are torn along the direction of shear stress under the effect of grinding stress to form internal connected channels,leading to the linear fluorescent indication.Microporosity can be eliminated by decreasing the pulling rate and prolonging the pulling time appropriately,thus avoiding grinding cracks.