An investigation on subsurface generation in ultra-precision milling of nickel with multiscale crystal plasticity FE model

Abstract

The subsurface microstructure affects the mechanical properties, the service performance and reliability of the workpiece components especially in ultra-precision machining. This study proposes a multiscale crystal plasticity finite element (CPFE) model to study subsurface generation in ultra-precision raster milling (UPRM) of FCC alloy by considering the microscale chip thickness variations and size effect in ultra-precision milling process, the microstructure evaluation as well as the macroscopic mechanical behavior of FCC alloy. Ultra-precision diamond milling experiments are conducted to verify the developed CPFE model and study the subsurface damage characteristics of the raster milled pure nickel, including dislocation distribution and microstructure variation of pure nickel under different milling conditions. The effects of cutting speed and depth of cut on the subsurface features including the subsurface microstructure variation, distributions of Mises stress and cumulative shear strain as well as the strain gradient of subsurface are qualitatively and quantitatively evaluated by the established CPFE model.