Numerical Investigation of Dynamic Recrystallization Induced Microstructural Evolution in Cryogenic Burnishing of Co-Cr-Mo Biomaterial

This paper demonstrated the development of a finite element method (FEM) based model for simulating the dynamic recrystallization (DRX) induced surface and sub-surface microstructural evolution of Co-Cr-Mo biomaterial in cryogenic burnishing. The cryogenic cooling effect was simulated by adding a heat exchange window to the processing region. Johnson-Cook (J-C) was used as the constitutive model and modified by incorporating the flow stress softening behavior and the resulting grain refinement through a novel user subroutine based on the DRX mechanism of Co-Cr-Mo biomaterial. For predicting the effect of DRX during the burnishing process, a friction model with a friction coefficient value that changes due to DRX was developed. The predicted grain size was evaluated by comparing with the experimental data; good agreements were achieved between predictive and experimental results. Similar remarks appear to be justified regarding increased use of cryogenic cooling during burnishing (and machining) when superior surface conditions are desired.