Dislocation physics in the multilevel approach to plastic deformation

The advances in physics of plasticity and strength are linked in many respects with dislocation physics. The paper, while reviewing the state-of-the art of dislocation physics in the framework of the multilevel approach to plastic deformation, considers mechanisms of dislocation accumulation in a deformed material and basic factors responsible for dislocation accumulation rates. The scalar dislocation density is divided into dislocation structure components. Particular attention is given to geometrically necessary dislocations. The main object under study is a polycrystalline aggregate for which critical grain sizes are determined. The contributions of main types of defects to the flow stress are discussed.