Cyclic high-pressure torsion of nickel and Armco iron

Abstract

Cyclic high-pressure torsion, a modified version of high-pressure torsion, is applied to Armco iron and nickel. The results in terms of microstructure and flow stress are compared to samples deformed by conventional high-pressure torsion. For both processes and both materials, a saturation in the decrease of the structure size and the increase in the flow stress is observed. The minimum size of the structural elements which is obtainable is smallest for the conventionally high-pressure torsion deformed samples and increases with decreasing strain per cycle in cyclic high-pressure torsion.

Notes

† One cycle means a deformation in one direction, similar to one pass in ECAP, it corresponds to ½ cycle in conventional fatigue.