Plastic Deformation Governed by the Stress Induced Martensitic Transformation in Polycrystals

Abstract

In order to make a quantitative description of the plastic deformation of polycrystalline alloys governed by the stress induced matensitic transformation (SIM), the condition of yield by SIM is formulated for multiaxial stress states. The relation between the plastic strain of a crystallite and the volume fractions of individual martensite variants formed in the crystallite is also given. Owing to its simplicity, the Taylor model is suitable for the present purpose to visualize the essential features of polycrystalline SIM. However, the volume change accompanying the martensitic transformation violates the basic hypothesis of the Taylor model; the homogeneity of strain. This problem is coped with by dealing only with the deviatric stress, deviatric strain and the plastic work done by them in terms of the Taylor model, and then by evaluating the effect of the hydrostatic stress and volume change. This scheme may be useful in predicting the deformation behavior of polycrystalline shape memory alloys, including the effect of their texture.