Postcritical deformation of steels in plane stress state

We study the laws determining the mechanical behavior of materials at the postcritical deformation stage. Proportional tension-torsion tests of thin-walled tubular specimens of structural steels were carried out for various deformation trajectories to obtain experimental data about the work softening of steels under plane stress state conditions. The obtained experimental data were analyzed to determine the instant of time in the deformation process at which the transition to the postcritical stage occurs.