Microstructure based micromechanical modeling of microstructural scale deformation in stainless steel 316L using crystal plasticity FEM

Grains in polycrystalline texture have anisotropic deformation nature. This cause material to show completely different behavior at meso and micro scale than they do at macro scale. To be specific, deformation at these scales is heterogeneous and cannot be modeled using constitutive equation in continuum plasticity. In this paper, in order to investigate deformation behavior of 316L stainless steel at micro scale a crystal plasticity finite element (CPFE) modeling system has been developed. The crystal plasticity equations were implemented in the ABAQUS/Implicit FE code through a user-defined material subroutine, UMAT. Verification was done through comparing the CPFE result against those obtained through implementing crystal plasticity formulation in MATLAB software. Comparison show good agreement between the analytical and CFFE result. Afterward, three dimensional simulation of tensile test on Stainless Steel type 316L is carried out using CPFE method and continuum macro mechanic FE. Deformation characteristic and localization behavior of single grain specimen at tensile test has been captured and predicted using CPFE method; on the other hand, macro mechanic finite element is unable of predicting localization and evolution of lattice at micro and meso scale. At the last part, a set of CPFE analysis are conducted on representative volume elements with 10 Grain and 5 set of different grain orientations. Results show a scattering in plastic part of stress-strain response of material with switching from one set of grain orientation to another set. It has been found that the material behavior at these scales is highly direction dependent.