Micromechanical behaviors of duplex steel:: in situ neutron diffraction measurements and simulations

Recently, much attention has been paid to studying the micromechanical behavior of multiphase materials by virtue of their extensive engineering applications. A strong heterogeneity in stress exists in two-phase materials during loading due to the different thermal expansion coefficients and the respective mechanical properties of each individual phase. For one duplex stainless steel under uniaxial compression, the distributions of microstrains were characterized with the strain response of multiple reflections to the applied external stress for each phase by employing in situ neutron diffraction experiments. Based on these, the anisotropic elastoplastic properties of the duplex steel on microscales, i.e. phase size and grain size, were modeled using a two-phase viscoplastic self-consistent (VPSC) model involving lattice rotation (texture evolution). Good agreement between predictions and neutron diffraction measurements was found. The stress partition between phases and orientated grains was discussed to characterize the phase stress and the grain-orientation-dependent stress, thus the particular micromechanical properties of two-phase materials may be explored.