Strain hardening during high pressure torsion deformation

Severe plastic deformation has been applied to Armco iron and copper by means of high pressure torsion. The evolution of the shear stress during deformation was measured under different hydrostatic pressures. By applying a simple model for a strain hardening, the shear stress-shear strain curves are fitted and the influence of the hydrostatic pressure is studied. These results are compared to microhardness measurements, tensile strength and the microstructural evolution.