Influence of Anvil Alignment on Shearing Patterns in High-Pressure Torsion

A two-phase duplex stainless steel was used as a model material in order to investigate the development of flow patterns when processing using high-pressure torsion (HPT). The results show that double-swirls are visible on the disc surfaces when processing with controlled amounts of anvil misalignment but not when the anvils are in an essentially perfect alignment. There are also shear vortices visible on the disc surfaces when processing with controlled amounts of misalignment but not when using perfect alignment. These results demonstrate the need for exercising significant care when processing discs by HPT. Prior to introducing torsional straining, it is important to ensure that the upper and lower anvils are in good alignment to within approximate to 25 mu m.