School of Mechanical, Materials and Mechatronic Engineering


Severe plastic deformation (SPD) has been the subject of intensive investigations in recent years because of the unique physical and mechanical properties of ultrafine grained (UFG) materials fabricated by this technique. High pressure torsion (HPT) is one of the most widely used SPD techniques. The main aim of HPT processing is to produce extreme grain refinement and the ensuing strengthening of the processed material. There is no longer any doubt that this is achievable with most malleable and even with many hard-to-deform materials, and innumerable experimental results documented in the literatures are a convincing testimony to that. Despite this body of experimental evidence, the deformation mechanisms during the HPT process, which are pivotal in designing the routes to property improvement, are far from being understood. Up to now, a few numerical simulations have been reported. However, these simulations only gave reasonably satisfactory predictions due to the simplifications and shortcomings of the developed models, and are definitely insufficient to fully understand the deformation mechanisms of the HPT process. Therefore, a systematic study on modeling of plastic deformation behavior, texture evolution and grain refinement of the HPT process is essential.

In the present study, a three-dimensional crystal plasticity finite element method (CPFEM) model has been developed to offer a systematic understanding of the plastic deformation behavior, texture evolutions and grain fragmentation of single crystals during the full scale HPT process. The developed CPFEM model has been validated by comparing the simulation results with the experimental observations.



Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.