Mesoscopic plastic deformation and fracture of surface-hardened specimens under static tension

A study was undertaken to elucidate the mechanisms responsible for mesoscopic plastic deformation of surface-hardened 65Kh13 steel specimens in tension, in which microscopic uniform dislocation-mediated deformation in the bulk had been suppressed. It was found that, from the outset, plastic deformation evolved by propagation of localized deformation bands in conjugate directions of action of maximum tangential stress. In the stress-strain curve this showed up as a linear hardening stage. At a later deformation stage characterized by parabolic hardening, the specimen acquired a mesoscopic substructure whose elements experienced shear plus rotation. Fracture occurred at one of the mesoscopic bands where a strongly localized plastic deformation had evolved.