Multiscale micromechanical model of duplex low density steel with B2 ordered precipitates

摘要

In this study we reproduced the experimentally established micro-structure of a, Fe-15Mn-10Al-0.8C-5Ni, low density steel into a representative volume element (RVE), i.e. the smallest representative feature on which measurement can be made to yield a value representative of the whole structure. The pertinent structural parts were split into, an austenite (gamma) phase, micro-meter sized B2 precipitates located inside gamma and a composite ferrite (alpha) + nano-sized B2 "phase". We simulated the mechanical elastoplastic response of each of these parts through J(2) deformation theory of plasticity. The equivalent inclusion method and mean field approach were employed to describe the behaviour or precipitates. The simulated composite mechanical response was in good agreement with those measured through tensile tests. The simulated responses suggests that the type of chosen boundary condition affects the development of shear strain localization. It was found that in those gamma grains located between any closely spaced composite alpha + B2 the strain localization is pronounced. In addition, inhomogeneity between phases led to stress concentration which in turn intensified the localization.