A finite element method and fast Fourier transform based crystal plasticity simulations study on the evolution of microstructure and mechanical properties of gradient structure copper

A combinatorial experimental and multi-scale simulations study has been performed to understand the role of microstructural heterogeneity on the deformation behaviour of a copper plate with a gradient layer produced by the surface mechanical grinding treatment (SMGT). Finite element analysis was employed to estimate the deformation during the SMGT process. Electron back scatter diffraction analysis indicated shear-type texture at all locations across thickness along with a continuous gradient of geometrically necessary dislocation (GND) density, resulting in an increasing trend of hardness from 81 +/- 3 HV at the bottom to 119 +/- 1 HV at the top. The SMGT samples showed similar to 22 % improvement in yield and tensile strength with comparable ductility compared to the base material. Full field crystal plasticity simulations using the Dusseldorf Advanced Materials Simulation Kit (DAMASK) successfully captured the global stress-strain response, texture evolution, and multi-length scale stress-strain partitioning along the thickness during tensile deformation. The improvement in the yield strength of the SMGT samples was attributed to dislocation strengthening and grain size strengthening while the strain hardening behaviour was explained by the presence of higher GNDs in the SMGT sample compared to the base metal. Thus, a robust process-microstructure-mechanical property paradigm has been established for the SMGT copper.