Fracture Failure Analysis of High-pressure Turbine Blades ofIIStage

All tow-stage high-pressure turbine blades fractured during the process of testing the engine.The fracture surface of the blades and the inner wall of the exterior ring of the tow-stage high-pressure turbine were observed. The microstructure of the blades was investigated,and fracture character and cause were analyzed.The results show that the fracture of the tow-stage turbine blades is overload fracture.The fracture of the blades was not related to the material and machining process.The fracture was caused by serious friction between the blades and the exterior ring. The friction between the blades and the exterior ring results from the elongation of the blades caused by short-time over-temperature.Meanwhile,the decline of high-temperature strength of the blades caused by short-time over-temperature contributed to the fracture.