Abstract
Magnesium alloy sheets in room temperature have unusual mechanical properties such as high in-plane anisotropy/asymmetry of yield stress and hardening behavior. In this paper, the continuum plasticity models considering the plastic behavior of AZ31B Mg alloy sheet were derived. A new hardening law based on modified two-surface model was developed to consider the general stress-strain response of metals including Bauschinger effect, transient behavior and the unusual asymmetry. Three deformation modes observed during the continuous tension/compression tests were mathematically formulated with simplified relations between the state of deformation and their histories. To include the anisotropy and asymmetry of the initial yield stress, the Drucker-Prager's pressure dependent yield surface was modified by adding anisotropic constants.
