Regularities of plastic deformation and fracture on mesolevel of surface-hardened specimens under static tension

Mechanisms of plastic deformation on a mesoscale level are investigated using surface-hardened specimens of steel 65Kh13 in which the uniform dislocation strain is suppressed on a microlevel and in the bulk of the specimen. It is shown that the plastic deformation under tension from the very beginning proceeds through propagation of localized deformation lines in conjugated directions of maximal tangential stresses. This process corresponds to the appearance of a linear hardening stage at the stress-strain curve. The masoscopic substructure occurs at the later stage of deformation which is characterized by parabolic hardening.