The thermal compression deformation behavior and microstructure evolution of 2 200 MPa ultra-high-strength steel were experimentally investigated using a Thermomastor-Z thermal simulation machine. Stress-strain curves under different strain rates (0.01 s⁻¹, 1 s⁻¹, and 5 s⁻¹) and deformation temperatures (850–1 150 ℃) with an engineering strain of 60% were tested. By analyzing the stress-strain curves and conducting EBSD analysis on deformed samples, the effects of strain rates and temperatures on the deformation resistance and dynamic recrystallization process of 2 200 MPa ultra-high-strength steel were studied. The recrystallization activation energy of the experimental steel was determined through regression calculations. The results indicate, 1) Higher deformation temperatures and lower strain rates result in lower deformation resistance of 2 200 MPa ultra-high-strength steel; 2) Dynamic recrystallization is activated at the strain rate of 0.01 s⁻¹ when the temperature ≥900 ℃; at strain rates of 1 s⁻¹ and 5 s⁻¹, dynamic recrystallization is activated when the temperature ≥1 000 ℃. During hot working processing, higher strain rates should be applied at temperatures ≥1 000 ℃, while lower strain rates are recommended below 1 000 ℃; 3) The calculated recrystallization activation energy of 2200 MPa ultra-high-strength steel is 421.20 kJ/mol; 4) A constitutive model for the flow stress of 2 200 MPa ultra-high-strength steel was established.
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