Structure development after twist channel angular pressing

Abstract

The twist channel angular pressing technology, based on the conventional equal channel angular pressing supplemented with an additional twist, was developed to increase the efficiency of severe plastic deformation imposed into a processed material during a single pass. The study investigated and compared sizes and preferential orientations of grains within commercial purity Al processed by TCAP and ECAP. The results revealed the grain refinement process to be very effective during TCAP (almost 90% of grains were smaller than 5 mu m after a single pass). Transmission electron microscopy was used to study sub-structure development within a TCAP-processed sample, the results showed grains with locations featuring accumulated dislocations and highly developed sub-grains after a single TCAP pass. The occurring softening processes also contributed to the fact that the TCAP-processed structure featured no strongly prevailing preferential grains orientation. The study was supplemented with a brief analysis of mechanical properties of TCAP and ECAP processed samples, which showed very favourable results for the TCAP-processed one.