Causes of crack formation in 1Cr11Ni2W2MoV steel high pressure turbine shaft

After the fatigue test of a 1Cr11Ni2W2MoV steel high pressure turbine shaft, a penetrating crack with a length of about 200 mm along the circumferential direction existed at the end face of the turbine shaft and the shaft body. The causes of crack formation were analyzed by means of macroscopic observation, metallographic examination and fracture analysis. The results show that the crack was a fatigue crack, and the material of the turbine shaft was normal. The main reason for the crack was that the coaxiality deviation of the mounting holes of the upper and lower support plate bearings of the turbine shaft was large, which led to the deflection of the turbine shaft during the fatigue test. The maximum stress position changed, and stress concentration occured at the corner of the end face and the shaft body, which promoted the formation of cracks.