Numerical Simulation of Severe Plastic Deformation during High Pressure Torsion Processing

The principle of achieving high strength and superior properties in metal alloys through the application of severe plastic deformation has been exploited in the metal processing industry for many decades. The High Pressure Torsion (HPT) process is one of the most promising techniques for imposing very high strains to a bulk solid without introducing a significant change in sample dimensions. The HPT process involves large shear and compressive plastic deformations, and offers the possibility to deform the material under very high hydrostatic pressures (up to several GPa), with continuous control of the degree of deformation. This process can produce exceptional levels of grain refinement, and provides a corresponding improvement in mechanical properties. It is of paramount importance that the shape of the sample is retained during the high pressure torsion process, by means of special tool geometries which effectively prevent free flow of the metal to obtain high hydrostatic pressures. The design of the mold geometry and the corresponding sample dimensions is an iterative process, which is governed by the constitutive behavior of the metal alloy under investigation. In this paper, we highlight the added value of Abaqus as a powerful numerical tool to assist in the design of high pressure torsion experiments. Vikar R&D, Ghent, Belgium