Numerical Simulation of Severe Plastic Deformation during High Pressure Torsion Processing

High pressure torsion (HPT) is a material processing that sample are subjected to very high hydrostatic plastic deformation. This process can produce exceptional levels of grain refinement, and provides a corresponding improvement in mechanical properties. To investigate the stress and strain distribution due to HPT process along the disc and the parameters that have effect on them, finite element simulation were conducted. The simulation demonstrate that the effective strains imposed on the sample are lowest in the disk centers and highest at the edges. The mean stresses during processing vary linearly with the distance from the center of the disk such that there are higher compressive stresses in the disk centers and lower stresses at the edges. By increasing the friction coefficient and the mold angle, mean stress decrease and stress variation along the disc diameters become more homogenies. Increasing pressure load lead to increase mean stress and heterogeneity along the disc.