Modeling of the ECAP Induced Strain Hardening Behavior in FCC Metals

Abstract

In this work, a multi-scale framework that couples a crystal plasticity (CP) scheme with a continuum dislocation dynamics (CDD) model is proposed to predict the material behavior, microstructure and texture during equal channel angular pressing (ECAP) processes. The strain hardening in the model is considered to result from both the increase in the dislocation density and the grain fragmentation. The grain fragmentation process is modeled by accounting for the grain-grain interaction and incorporating the concept of the geometrically necessary dislocations (GNDs) into the mean free path of the dislocations. GNDs result from grain boundaries restricting the free deformation of a grain, causing an internal plastic deformation gradient that subsequently leads to grain fragmentation. A commercial Al-1100 billet, with rolling texture, is ECAP processed under Route C for different numbers of passes. Mechanical, microstructure, and texture characterization is achieved for the received and ECAPed materials. The proposed model parameters are calibrated using the tensile true-stress true-strain curves of the unprocessed material at two strain rates. The ECAP-processed aluminum microstructure, texture, dislocation densities and the mechanical properties are predicted.