Hot Deformation Behavior and Microstructural Evolution of a Ni-based Alloy Turbine Disc

Hot deformation behavior and microstructural evolution of a Ni-based alloy turbine disc were investigated with the ranges of 1025–1100 °C and 0.001–1 s−1. According to work hardening (WH) curve, the critical strain (stress) for dynamic recrystallization (DRX) was calculated; The DRX volume fraction models were constructed to simulate microstructure evolution behavior by Avrami equation. The microstructure analysis of the studied alloy was investigated by OM and TEM. At 1075 °C/0.1 s−1, the intragranular γ' phases can effectively prevent dislocations movement, forming a high density of dislocation substructures and subgrain boundaries in the grain. The critical stresses for DRX increase with the increase of strain rates and the decrease of temperatures, and the critical strains for DRX increase with decreasing temperature. DDRX are the main nucleation mechanisms, and the grain boundaries provide nucleation sites for dynamic recrystallized grains. The DRX behaviors were predicted by DRX volume fraction models, and the simulated results are close to the experimental results.