An evaluation of the mechanical properties, microstructures and strengthening mechanisms of pure Mg processed by high-pressure torsion at different temperatures.

Abstract

Pure Mg samples were processed by high-pressure torsion (HPT) for up to 10 turns at temperatures of 293 and 423 K. The microstructures of these samples were significantly refined and bimodal structures were obtained after 10 turns of HPT processing at both 293 and 423 K. Tensile experiments were conducted at room temperature to reveal the mechanical properties of pure Mg subjected to HPT processing at different temperatures. The yield strength increased with increasing numbers of turns after processing at 293 K whereas the yield strength showed almost no variation with increasing numbers of turns at 423 K. Pure Mg processed at 423 K exhibited a higher strain hardening ability and a larger uniform elongation than after processing at 293 K. Calculations show the grain size, bimodal structure and dislocation density are the main factors affecting both the yield strength of the material and the work hardening behavior.