Study on Hot-Compressive Deformation Behavior and Microstructure Evolution of 12Cr10Co3MoWVNbNB Martensitic Steel

Abstract

Herein, to improve the microstructure homogeneity of 12Cr10Co3MoWVNbNB steel for turbine blades after forging, the hot deformation behavior and microstructure evolution of the steel are systematically investigated using a hot-compression experimental setup under the conditions of 950–1150 °C and strain rate of 0.001–10 s⁻¹. A strain-compensated constitutive equation is established based on the flow curves and the accuracy of its prediction is verified. By combining hot processing map with microstructure observation, the optimal hot processing window is determined to be 1075–1150 °C and 1–10 s⁻¹, within which the grain size can be refined to 14.24 μm. Electron backscatter diffraction is employed to investigate the microstructural evolution and dynamic recrystallization (DRX) nucleation mechanism of the deformed samples, revealing that discontinuous DRX characterized by strain-induced grain-boundary migration is the dominant nucleation mechanism. Additionally, the deformation conditions significantly affect the distribution of dislocation density and local misorientation, as well as the transition from low-angle grain boundaries to high-angle grain boundaries, which ultimately lead to the differences in DRX fraction and microstructure.