Microstructure evolution of high carbides Ni-based superalloy during hot compression process

Abstract The high carbides Ni-based superalloy was conducted with a 60% deformation amount to investigate the hot compression behavior by the Gleeble hot compression simulation experiment under the deformation temperature of 1000 °C, 1100°C, and 1200 °C with the strain rate of 0.1 s −1 . The microstructure evolution, stress distribution, and carbide characteristics of the superalloy under different hot compression conditions were analyzed using ECCI and EBSD techniques. The results indicate that when the deformation temperature was 1000 °C there was a larger stress gradient, and higher recrystallization driving energy, but phase transition or recrystallization didn’t occur. When the deformation temperature was 1100 °C or 1200 °C there was less stress gradient and more recrystallization microstructure, and the carbides would undergo phase transformation, M 6 C + γ → M 6 C + M 23 C 6 + γ → M23C 6 + γ. At the same time, M 23 C 6 underwent decomposition, the alloy elements such as Cr, W, and Mo dissolved back into γ matrix, and the ellipsoidal M 23 C 6 became the network. There were no cracks around the carbides at different deformation temperatures, but the carbides can’t exist stably at higher temperatures than 1100 °C, therefore the service temperature of the alloy should be below 1100 °C.