<p>The hot deformation behavior of GH3230 superalloy under selected deformation conditions ranging from 950 to 1150&#xa0;°C with strain rates ranging from 0.01 to 10 s<sup>–1</sup> was studied through isothermal hot compression experiments. Based on the obtained flow stresses, a strain-compensated Arrhenius-type model was developed for the description of hot deformation behavior, and the consistency of the predicted flow stresses with the experimental values confirms the accuracy of the developed model. Furthermore, the processing maps were constructed and classified into the instability domain, low-dissipation stability domain and high-dissipation stability domain in accordance with the dynamic material model and the instability criterion. Microstructure observations indicated that the instability domain exhibits the adiabatic shear bands formation, and the low-power dissipation domain exhibits partial dynamic recrystallization (DRX), with the temperature increase/strain rate decrease being favorable for the DRX. The high-dissipation stability domain was occupied by uniformly fine equiaxed grains, and was identified as the optimal processing window, which corresponds to the deformation conditions at 1070–1150&#xa0;°C with strain rates ranging from 0.01 to 0.15 s<sup>–1</sup>. Moreover, various DRX mechanisms are observed to occur during the hot deformation, which include the discontinuous dynamic recrystallization, characterized by nucleation at bulged boundaries, the continuous dynamic recrystallization with subgrain progressive rotation and the particle stimulated nucleation mechanism with stimulated nucleation of carbide particles.</p>

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Characterization of hot processing behavior, microstructure evolution and underlying mechanism of GH3230 superalloy during hot deformation

  • Biao Zhang,
  • Quan Ju,
  • Rui-wen Song,
  • Bai-gang Wang,
  • Hao Wang

摘要

The hot deformation behavior of GH3230 superalloy under selected deformation conditions ranging from 950 to 1150 °C with strain rates ranging from 0.01 to 10 s–1 was studied through isothermal hot compression experiments. Based on the obtained flow stresses, a strain-compensated Arrhenius-type model was developed for the description of hot deformation behavior, and the consistency of the predicted flow stresses with the experimental values confirms the accuracy of the developed model. Furthermore, the processing maps were constructed and classified into the instability domain, low-dissipation stability domain and high-dissipation stability domain in accordance with the dynamic material model and the instability criterion. Microstructure observations indicated that the instability domain exhibits the adiabatic shear bands formation, and the low-power dissipation domain exhibits partial dynamic recrystallization (DRX), with the temperature increase/strain rate decrease being favorable for the DRX. The high-dissipation stability domain was occupied by uniformly fine equiaxed grains, and was identified as the optimal processing window, which corresponds to the deformation conditions at 1070–1150 °C with strain rates ranging from 0.01 to 0.15 s–1. Moreover, various DRX mechanisms are observed to occur during the hot deformation, which include the discontinuous dynamic recrystallization, characterized by nucleation at bulged boundaries, the continuous dynamic recrystallization with subgrain progressive rotation and the particle stimulated nucleation mechanism with stimulated nucleation of carbide particles.