2019 Volume 60 Issue 7 Pages 1177-1191
The High Pressure Tube Twisting (HPTT) process was first proposed in 2009 as an efficient new Severe Plastic Deformation (SPD) process. Since then it has been successfully applied on many different materials and the results have been reported in several publications and thesis works. The purpose of this overview is to present and evaluate the main results of the published papers and thesis works and also to present new contributions. Special attention is given to the strain gradient which appears in the tube wall for which a new empirical formula is presented.