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In order to examine the dynamic recrystallization (DRX) behaviors of Co-29Cr-6Mo alloy with additions of both C and N (hereafter CCMCN alloy), uniaxial compression tests in the temperature range of 1273 to 1473 K and strain rates of 0.01 to 30 s À1 were carried out. The influence of hot forging conditions (i.e., temperature, strain rate, and strain) on the microstructure of deformed sample was investigated in detail by means of electron backscattering diffraction (EBSD) and optical microscopy (OM). The results revealed that the initial microstructure is a stable face-centered cubic (FCC) phase with a large number of M 23 C 6 precipitates both inside the grains and at grain boundaries. The DRXed grains were observed to be uniformly distributed and to decrease with strain. The high volume fraction of AE3 boundaries after the DRX was observed, indicating a close relation between the DRX mechanism and AE3 boundary formations. In addition, the activation energy Q of CCMCN alloy was observed to be higher as compared to those of alloys without C or N addition and that with N addition.

The high-temperature deformation behavior of Co-29Cr-6Mo-0.23C-0.14N alloy was investigated by carrying out compression tests; the tests were carried out in the temperature range of 1000-1200 C and strain rates ranging from 0.01 to 30 s À1 with a height reduction of approximately 65%. The optimum hot-working conditions were determined from the processing map based on the dynamic materials model. Dynamic recrystallization was observed to occur over the entire temperature and strain rate range. However, uniformly sized grains were formed for strain rates higher than 1 s À1 , which is considered to be the optimum hot-working condition. In addition, authors suggested that in extremely low stacking fault energy alloy, explosive and homogeneous formation of mechanical twinning should be considered to be stable state, and new processing map with more detailed description of deformation mechanism seems necessary in future.

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