Abstract: Recent progress and unsettled problems concerning the plastic instability (shear band, necking, wrinkling) in metal forming processes are reviewed in this paper. The close relation between the prediction of plastic instability and the choice of constitutive laws is emphasized. It is pointed out that the predicted results strongly depend on the assumed constitutive laws. The effects of anisotropy, strain rate sensitivity, imperfection and its amplitude and inertia on plastic instability are discussed. Beside...