An examination of the elastic distortions of anvils in high-pressure torsion

Experiments and finite element modelling were used to examine the effect of elastic distortions of the anvils on plastic flow and sample geometry in the compression stage in high-pressure torsion. The results demonstrate that the curved disc surfaces observed consistently in HPT processing originate from elastic deformation of the anvils and the measured variations in the thicknesses of the samples depend upon the imposed pressure. It is shown also that the samples are further deformed during unloading of the anvils and this produces a peak in the strain in the central region of the disc as recorded in several experimental measurements of the local microhardness.