PLASTIC-DEFORMATION GOVERNED BY THE STRESS-INDUCED MARTENSITIC-TRANSFORMATION IN POLYCRYSTALS

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 to visualize the essential features of polycrystalline SIM. However, the volume changes accompanying the martensitic transformation violate the homogeneity of strain. This problem is solved by dealing only with the deviatric stress, deviatric strain and plastic work done by them in terms of the Taylor model and 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 textures.