Papers by Author: Dmitry Orlov

Abstract: In the present work, effects of loading scheme and strain reversal on structure evolution are studied by using high pressure torsion (HPT) and twist extrusion (TE) techniques. High purity aluminum (99.99%) was processed at room temperature up to a total average equivalent strain of ~4.8 by TE and HPT with two deformation modes: monotonic and reversal deformation with a step of 12˚ rotation. It was revealed that microstructural change with straining observed in pure Al was a common consequence of the SPD processing and was not affected significantly by the loading scheme. At the same time, it was found that strain reversal retarded grain refinement in comparison with monotonic deformation.

Abstract: All the SPD techniques introduce reversal straining principally, but effects of the reversal deformation on structure evolution were not studied directly yet. In the present work, an attempt was made to manage structure in pure (99.99%) Al by strain reversal through high pressure torsion (HPT). Total accumulated deformation up to equivalent strain ~8 was used. General trend of the grain refinement is similar for both deformation modes; and it is typical with all other SPD processed FCC metals. At the same time, the difference in microstructure evolution at the vicinity of the specimen axis and with increasing distance in the radial direction introduces microstructural heterogeneities which are specific features of the reversal straining. In the monotonic deformation process the A ({111}<011>) fiber is gradually substituted by the C component ({ 0 0 1}< 1 1 0>) with increasing strain before it is found to weaken. In the reverse straining process the A fiber is found to dominate the deformation texture in the low strain region. In the reverse straining process at high strain level, a {001}<100> component appear.