Experimental study of Baushinger effect and yield surface at elastoplastic deformation of metals

This work contains results of the experimental investigation on repeated sign-variable loading at stretching compression of a thin-walled tubular specimen from steel 45 in an automatized computational and experimental installation SN-EVM. Аlso presents the results of the experimental assessment of the Baushinger effect and the influence of various admissions on residual deformation on it. The influence of the admission on residual deformation on definition of secondary offset yield stress was investigated, as well as on initial and subsequent radius function and position of the center of a hypothetical spherical yield surface in stress space in the plastic-flow theory. According to the results of the investigation, the parameter characterizing the Bauschinger and the radius function of the yield surface increase on the increase of admission on residual deformation effect, yet the displacement of the center of the yield surface decreases. It is shown that the parameter characterizing the Bauschinger effect decreases on the increase of the length of the arc of plastic deformation and tends to a stationary value. It is experimentally discovered that for steel 45 the displacement of the center of the yield surface increases on the increase of the length of the arc of plastic deformation. It is also established that the radius of the spherical yield surface lowers temporary, and then increases on the increase of the length of the arc of plastic deformation radius. Thus, in some mathematical models of plastic-flow theory temporary decrease of the radius of the yield surface (contraction of the yield surface) at the beginning of the process of plastic deformation is not associated with the definition of the yield stress for the admission on residual deformation.