On the modified kinetics model describing the dynamic recrystallization behavior during hot deformation of Incoloy 925

Abstract

The isothermally hot compression tests of Incoloy 925 were conducted over a temperature range of 900–1150 °C and strain rate of 0.01–10 s−1 to investigate the dynamic recrystallization (DRX) kinetics behavior and its effect on the microstructure evolution. The values of DRX fraction under different deformation conditions were evaluated through electron backscatter diffraction analysis combined with artificial neural network approach. The DRX behavior was also investigated based on the traditional Avrami-DRX kinetics model and the strain-rate dependent Avrami-DRX kinetics model modified by genetic algorithm & BiHill function, respectively. The results reflected that the modified model shows a better robustness to describe the DRX behavior under the deformation condition with a relatively low DRX fraction or at the domain with higher strain rate. Besides, the crystallographic orientation parallel to the compressive direction tends to form the fiber highlighted by the deformed grains, while the predominant orientations of DRX grains show a tendency towards fiber. Moreover, the transition rule of the main DRX mechanism was further studied by discussing the linear relationship between the Z parameter and DRX grain size.

Keywords

• Nickel-based alloy
• Hot deformation
• Dynamic recrystallization
• Genetic algorithm
• Kinetics model