Hot deformation behavior of C276 superalloy in shifted strain rate compression: Experiments and cellular automaton modelling

Plastic deformation is always inhomogeneous and complicated during hot processing of the superalloy component, making it hard to accurately predict the flow behavior and microstructure evolutions which may deviate greatly from those results obtained during traditional compression tests with a constant strain rate. The hot deformation behavior of a Ni-Cr-Mo based superalloy C276 in shifted strain rate conditions was investigated and a comparison with the constant strain rate compressions was conducted. The flow stress was found to immediately change after varying the strain rate. The strain rate sensitivity (m), which is the exponent of stress change against the strain rate, was calculated to about 0.16-0.24 for C276 superalloy at 1323 K with strain rate in the range of 0.001-1 s(-1). The strain rate variation affected the microstructure evolution greatly, leading to different dynamic recrystallization (DRX) tendencies from the compressions with a constant strain rate. Shifting the strain rate from high value to low value resulted into a higher extent of DRX in comparison with the reverse process. A cellular automaton (CA) model, considering the evolutions of dislocation density, recrystallization nucleation and grain growth in deformation procedure, was developed to simulate the microstructure evolution and stress response in shifted strain rate compressions. The successful predictions by the CA model showed a good potential application of this approach in understanding the DRX behavior in non-constant hot processing of C276 superalloy. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The hot deformation behavior of a Ni-Cr-Mo based superalloy C276 was investigated under shifted strain rate conditions, revealing different flow stress and microstructure evolutions compared to constant strain rate compressions. A cellular automaton model successfully predicted the dynamic recrystallization behavior in non-constant hot processing of C276 superalloy.