Crystal cyclic plasticity and anisotropy of 316L manufactured by Selective Laser Melting
Additively manufactured (AM) 316L steel exhibit extraordinary high yield strength. Extremely fine cells are being formed due to rapid cooling and dense dislocations which responsible for the macroscopically high yield strength of AM316L. Analysis of the microstructure of AM316L have revealed deformation behaviour involving dislocation slip ad well as deformation twinning. Detailed microstructure characterisation and in-situ cyclic loading will be coupled with crystal plasticity-based finite element modelling (CP-FEM) to examine micromechanism and plastic anisotropy in AM316L. Deformation (e.g. cyclic hardening, softening and saturation) response and the corresponding microstructural evolution of AM316L during cyclic loading at room temperature will further be studied. In particular, the physical interpretation and the role of internal stresses are thoroughly evaluated in order to better comprehend the relationship between microstructural evolution and cyclic deformation response. A physically-based evolutionary constitutive model aiming at accurately representing the complex cyclic deformation response of the material to describe the change in microstructural condition and its relationship with internal stress variables is proposed. In addition, dislocation-dislocation and twinning interactions will be incorporated in the model to capture the plastic anisotropy. Neutron diffraction at ENGIN-X (ISIS, UK) is used to study the twinning behaviour in-situ under cyclic deformation to understand the cyclic anisotropy and provide data for the crystal plasticity model validation.