Analysis on Ultra-high Cycle Fatigue Crack Initiation and Propagation Characteristics of DZ125 Superalloy

Crack initiation and propagation are important aspects of studying ultra-high cycle fatigue behavior of DZ125 superalloy. The analysis and discussion were carried on the effect of the temperature and surface status on the ultra-high cycle fatigue crack initiation and propagation character of DZ125 superalloy. The ultra-high cycle fatigue crack initiation position and propagation pattern of DZ125 superalloy vary with temperatures. All fatigue cracks initiated from the surface and propagated mainly in the tensile pattern at room temperature. All fatigue cracks initiated from the subsurface and propagated mainly in the shear pattern at 700 ℃. The ultra-high cycle fatigue crack initiation position and propagation pattern were different for DZ125 superalloy before and after laser shock processing at room temperature. The fatigue crack initiated from the cavities within the DZ125 superalloy and propagated entirely in the shear pattern.