Deformation induced misorientations: Initial stage of subgrain formation as a plastic instability

Formation of periodic misorientations of crystal lattice is treated in the framework of continuum crystal plasticity as a bifurcation from a uniform t o a non-homogeneous mode of plastic deformation. To enable clear identifica tion of the origin of the instability, a simple rigid-plastic model of a cr ystal deforming in plane strain is developed and successively analyzed in s everal steps. Continuum theory of dislocations is utilized to derive the di slocation patterns corresponding to the emerging misorientations which arc interpreted as initial stages of deformation induced misoriented cell or su bgrain structures.