The main target of this study is to optimize the microstructure and to achieve an optimization for the mechanical properties in a biomedical Co-Cr-Mo (CCM) alloy with the nominal composition of Co-28Cr-6Mo (mass%) subjected to high-pressure torsion (HPT) and subsequent short annealing. The γ → ε phase transformation and grain refinement occur in the CCM alloy subjected to HPT processing at an equivalent strain (εeq) of 2.25 (CCMHPT). The HPT processing causes a decrease in the elongation due to the formation of an excessive amount of ε phase. For removal of the excessive amount of ε phases, the CCMHPT was subjected to a short annealing (CCMHPTA). The effect of the short annealing temperature (1073 K, 1273 K, and 1473 K; annealing time was fixed at 0.3 ks) on CCMHPT was investigated. In addition, the effect of the length of duration for the short annealing (0.06 ks, 0.3 ks, and 0.6 ks;) for a fixed annealing temperature of 1273 K on CCMHPT was studied. CCMHPTA(1273 K) annealed for 0.3 ks shows a good optimization of mechanical properties that include high strength and large elongation owing to its ultrafine-grained microstructure, and removal of excessive ε phases.
- Cobalt-chromium-molybdenum alloys
- Grain refinement
- High-pressure torsion
- Short annealing