Fatigue crack propagation behavior of IN718 superalloy aged with temperature/stress coupled field

Fatigue crack propagation behavior of IN718 superalloy aged with or without stress was investigated. The alloy aged with stress exhibited a higher fatigue crack growth rate and a lower fatigue threshold compared to that without stress. Both the restricted dislocation planar slip and the decreased difference in orientation of the activated slip system between adjacent grains were promoted by coarse gamma '' phases, which increased the local plastic deformation and reduced the crack deflection. The accelerated coarse gamma '' phase caused by applied stress was the key factor for the degradation of fatigue crack propagation resistance of the alloy aged with stress.

Automated summary

The fatigue crack propagation behavior of the IN718 superalloy aged with stress was found to exhibit a higher crack growth rate and lower fatigue threshold compared to that aged without stress. This was attributed to the promotion of restricted dislocation planar slip and decreased orientation difference of the activated slip system between adjacent grains by coarse gamma '' phases, leading to increased local plastic deformation and reduced crack deflection. The accelerated formation of coarse gamma '' phases caused by applied stress was identified as the key factor in the degradation of fatigue crack propagation resistance in the alloy aged with stress.