A crystal plastic finite element model for the effect of surface integrity on multiaxial fatigue life after multistage machining processes.

Surface integrity influences the material fatigue performance significantly, but most micromechanical models based on crystal plasticity only consider the microstructure of the matrix. In this paper, a crystal plastic finite element modeling method was proposed, which simultaneously considered surface roughness, residual stress, and gradual microstructure. It was verified through multiaxial fatigue experiments of materials processed by different multistage machining processes. The results show that larger axial residual compressive stress and smaller grain size can lead to higher multiaxial fatigue life. The existence of residual compressive stress causes the location of material crack initiation to decrease from the surface layer to the subsurface layer. The proposed model can predict the multiaxial fatigue life of materials within a 50% error band. Highlights: A crystal plasticity model considering surface integrity was established.The multiaxial fatigue life of turning specimens is higher than that of grinding.The residual compressive stress cause crack initiation at the subsurface layer.A fatigue life prediction method was proposed within a 50% error band. [ABSTRACT FROM AUTHOR]