An overview of flow patterns development on disc lower surfaces when processing by high-pressure torsion

Abstract

Stainless steel was selected to study the flow patterns developed with anvil misalignments of 100, 200 and 300 μm on the disc lower surfaces during processing by high-pressure torsion (HPT) through totals of up to 16 turns. A pair of anvils having a roughness of Ra ≈ 15 μm was utilized to investigate the flow pattern development. Discs subjected to only compression in HPT exhibit similar characteristics to the as-received material in the phase domains and there were no overall curvatures of the austenitic (γ) and ferritic (α) phases. Double-swirl flow patterns were not observed in the 1 turn sample but they appeared on the disc lower surfaces after 5 and 16 turns with all three-anvil alignment conditions. There was no significant difference in the double-swirl configuration size for the 5 and 16 turns samples with different amounts of anvil misalignments. These results have important implications for processing metals by HPT.

Keywords

• Double-swirl
• Flow pattern
• High-pressure torsion
• Stainless steel