An Investigation on Constitutive Relation and Dynamic Recrystallization of Hastelloy C-276 Alloy During Hot Deformation

Hot compression tests of Hastelloy C-276 alloy were conducted at the temperature ranging from 1000 to 1250 °C and strain rate ranging from 0.01 to 10 s⁻¹. The constitutive relation and critical points of dynamic recrystallization (DRX) of the Hastelloy C-276 alloy were analyzed. The flow stress curves were corrected to tackle the problems of the influence of the adiabatic heating and friction. It was revealed that a five-order polynomial was suitable to solve the problem of the influence of strain. The critical strains of DRX could be expressed by the calculation from strain hardening rate as \( \varepsilon_{c} = 7.67 \times 10^{ - 4} Z^{0.144} {\text{and }}\varepsilon_{c} \approx 0.78\varepsilon_{p} \). Microstructural evolution revealed that the development of DRX of the alloy was complete at high temperature and low strain rate and the DRX grain size increased with the increase in temperature. The volume fraction of DRX was increased, and the grain size of DRX was also slightly increased with the increase in strain. The main nucleation mechanism of DRX was discontinuous dynamic recrystallization (DDRX), which was characterized by the grain boundary bowing nucleation mechanism coupled with the twinning-induced nucleation mechanism. Σ3 twins also contribute to the grain refinement and homogenization during hot deformation. The grains of C-276 alloy were refined significantly, and the microstructural homogeneity was improved effectively during hot deformation at high temperature and low strain rate. By choosing the suitable hot working processing parameters, the refinement and uniform distribution of grains of Hastelloy C-276 alloy could be obtained.