Microstructure evolution and peculiarities of strain hardening in aluminum processed by dynamic channel angular pressing

Abstract A study of aluminum subjected to high-rate shear deformation via dynamic channel angular pressing (DCAP) has been performed to investigate the main patterns of microstructure evolution and the peculiarities of strain hardening. A principal feature of the microstructure formed during the first DCAP pass is the occurrence of large misorientation deformation bands. Examination of their constitution and crystallography showed that at least some of them appear to be a product of deformation twinning. No indications of twinning were however found in the microstructure after 4 DCAP passes. At this stage of the processing, grain refinement occurs mainly through ordinary fragmentation, namely, a subdivision of crystallites into regions, whose misorientations gradually increase from low-angle to high-angle ones, while the role of deformation bands becomes less distinct. Nevertheless, despite considerable grain refinement, about 80% of strengthening after 4 DCAP passes is provided by the dislocation substructure, while the contribution of high-angle boundaries to the strengthening remains low.