Parallel tubular channel angular pressing (PTCAP) as a new severe plastic deformation method for cylindrical tubes

A new severe plastic deformation (SPD) technique entitled PTCAP is proposed to be suitable for deforming cylindrical tubes to extremely large strains. The tube constrained between mandrel and die is pressed by a first punch into a tubular angular channel with two shear zones and the diameter of the tube is increased and then pressed back to the initial dimension by the second punch. This process was applied to a commercially pure copper and a significant grain refinement resulted to a mean grain size of 150-300 nm was achieved even after a single pass PTCAP. Finite element (FE) results showed that the equivalent plastic strain of about 3 +/- 0.05 could be achieved at the end of the second cycle of PTCAP while it is about 3 +/- 0.4 at the end of the recently developed TCAP process. So, there is excellent strain homogeneity through the length and thickness of the PTCAP processed tube. Also, from the numerical results it was obtained that 57% lower loads are required for the PTCAP compared to TCAP. So, this new SPD process has two important advantages of excellent strain homogeneity and requiring a lower load. (C) 2012 Elsevier B.V. All rights reserved.