Surface integrity and fatigue failure behavior of nickel based alloy blades: After cutting, vibration finishing and shot peening

This article selected three processes to prepare nickel based alloy GH4169G blades, tested the surface integrity changes of different processes, conducted high cycle vibration fatigue tests, and studied their failure mechanisms. The results indicate that the milling polishing vibration precision machining (MV) process can effectively reduce the surface roughness of milling (M) process blades, while the milling polishing vibration precision machining shot peening (MVSP) process significantly improves the residual compressive stress and hardening layer level of blades. The MVSP process blades have the best vibration fatigue life, with an average life of 4.91 × 10⁶, which is 775.2 % higher than the M process blades. The fatigue life of the blades has been significantly improved. After MV process treatment, the blade undergoes a transition from multi-source fatigue caused by M process to surface single source fatigue crack initiation. The crack initiation location of MVSP process blades shifted from the surface to about 0.097 mm below the surface, and shot peening significantly improved the fatigue crack initiation life of the blades.