Dynamic recrystallization in biomedical Co-29Cr-6Mo-0.16N alloy with low stacking fault energy

Dynamic recrystallization (DRX) behaviors of biomedical Co-29Cr-6Mo-0.16N (CCMN) alloy were analyzed in detail in hot compressive tests. At low temperature (≤1050 °C) and low strain rate (≤1 s^-1), DRXed grains preferentially nucleate along pre-existing grain boundaries or σ3ⁿ boundaries, with a result of necklace microstructure broadening with increasing strain; while at higher temperature and/or higher strain rate, DRX occurs uniformly in matrix resulting in homogenous and texture-free fine grained microstructure. These two kinds of DRXed microstructures formed in CCMN alloy are related the repeated formation of annealing twin during hot deformation, which was determined by both the temperature and the activity of stacking fault formation. It was also found that the σ3ⁿ boundaries formed at lower strain level will evolve into general high angle grain boundaries (HAGB) with further straining. A schematic model for DRX mechanism of CCMN alloy was proposed with respect to temperature, strain rate, and strain.