Microstructure Evolution Mechanism of 4Cr13 Steel During Thermal Deformation

To investigate the thermal deformation behavior and microstructural evolution of 4Cr13 steel, and to clarify how deformation enhances its microstructure and properties, hot compression tests were conducted on the material at various deformation temperatures (890 °C, 970 °C, 1050 °C, and 1130 °C) and strain rates (0.1 s−1 and 10 s−1), followed by spheroidizing annealing. The results indicate that thermal deformation significantly refines the final microstructure and improves material properties. With increasing deformation temperature, the carbide count decreases, and recrystallization becomes more extensive. At a deformation temperature of 1130 °C and a strain rate of 10 s−1, the microhardness of the specimen reached a maximum value of 738.85 HV. Furthermore, the thermal deformation process stores considerable strain energy in the material, which acts as the driving force for static recovery and recrystallization during annealing. This promotes the development of a spheroidized, equiaxed grain structure free from distortions, thereby reducing the influence of the microstructural inheritance effect on the martensitic structure after annealing.