Slip identification from HR-DIC/EBSD: Incorporating Crystal Plasticity constitutive laws

Abstract

It is well known that dislocation slip plays a major role in plastic deformation of polycrystals. Depending on the crystal’s symmetry, only a limited number of Slip Systems (SSs) are possible, and their activities depend on the crystal orientation with respect to the applied stress. High Resolution Digital Image Correlation (HR-DIC) can be used to get the full-field measurements of displacement fields on the surface of the strained material during an in situ tensile test, whereas the EBSD technique provides local crystallographic orientations. Therefore, coupling them can lead to full description of the local slip activities. Recently, an algorithm (named SSLIP) was proposed in the literature to automatically estimate the plastic activity from HR-DIC and EBSD data. The aim of the present paper is first to improve this algorithm so that it works for incremental straining, and to propose a way to take account for the anisotropic behaviour through a well-known set of Crystal Plasticity (CP) constitutive laws. It is shown that slip identification, together with those CP laws, can be used to estimate the tensile stress at grain scale. The influence of the DIC resolution is investigated and ‘‘correction rules’’ for small grains are proposed. Finally, the experimental results are compared against those found using the CP Finite Element Method (CPFEM), showing good consistency, specially in terms of active SSs and local stress.