Continuous high-pressure torsion using wires

A newly developed severe plastic deformation method, continuous high-pressure torsion (CHPT), was modified for continuous processing of metallic wires. In this study, using the CHPT, wires of high-purity aluminum (99.99%) and copper (99.999%) with diameters of 2 mm and total lengths of 100 mm were successfully processed by employing the same features as conventional high-pressure torsion (HPT) technique. The results of hardness measurements, 35 Hv for Al and 116 Hv for Cu, after CHPT at an imposed equivalent strain of ~13 were consistent with those of conventional HPT using disk and ring specimens, as well as with those of CHPT using sheet specimens. Transmission electron microscopy (TEM) demonstrated that the microstructural elements are elongated in the shear direction after CHPT. The average grain size reaches the steady-state level, ~1.3 μm, in Al, but the microstructure is at the non-steady state in Cu with subgrain sizes in the range of 0.3–4 μm.