Subgrain Effect on Grain Scale Plasticity of NiTi Shape Memory Alloy Under Canning Compression: A Crystal Plasticity Finite Element Analysis

The subgrain effect of NiTi shape memory alloy during canning compression at 400 °C is investigated through electron back-scattered diffraction (EBSD) experiment, transmission electron microscope (TEM) experiment and crystal plasticity finite element (CPFE) simulation in explicit consideration of subgrain within each grain. Experimental investigations based on TEM and EBSD measurements confirm that the formation of subgrain actually results from the dislocation motion during canning compression. Numerical simulations based on the constructed polycrystalline models with various subgrains are used to investigate the subgrain effect during canning compression from a different point of view. In terms of texture evolution, subgrain effect does not change the tendency of texture evolution, but it contributes to the dispersed distribution with respect to the deformed grain/subgrain orientations. As for accumulative shear strain, subgrain effect contributes to sustaining larger plastic strain inside each grain, and it also results in the strain concentration near grain boundaries. With respect to von Mises stress, the subgrain effect facilitates the ease of stress concentration near grain boundaries and it contributes to possessing a homogeneous stress distribution within the inner part of each grain.