Analysis of microdamage in a nickel-base alloy during very high cycle fatigue

摘要

Fatigue damage in a metallic material during very high cycle fatigue can strongly be correlated to the microstructure. This paper provides a review and a discussion on the micro damage behaviours in a nickel-base alloy during very high cycle fatigue using microplasticity and material mechanics. The results show mat cyclic plastic deformation in this material can occur very locally even with an applied stress that is much lower than the yield strengdi. The fatigue damage occurs mainly at grain or twin boundaries because of local impingement and interaction of slip bands and these boundaries. The crystallographic properties, Schinid factors and orientations of grain and boundaries play very important roles to the fatigue damage. Subsurface fatigue crack initiation in the matrix is one of very high cycle fatigue mechanisms. Twinning and detwinning can also occur during the very high cycle fatigue process.