An Experimental Investigation Into the Plastic Flow and Strain Hardening of Mild Steel Under Proportional and Abruptly Changing Deformation Paths at a Controlled Rate

Abstract

Tension-torsion tests are reported on thin-walled tubes up to strains of the order of five percent. Attention was given to the question of whether, as has been suggested, in the continued loading after a sudden direction change in the deformation path, the behavior of the material quickly approaches that predicted by a von Mises plastic potential and isotropic hardening. The results show a slower approach of the deviatoric stress vector direction to the plastic strain-rate vector direction than had been expected, as well as considerable variations in the von Mises equivalent stress versus equivalent plastic strain curves.