Abstract: In order to predict the thermal deformation behaviour of AFA steel, high temperature hot compression experiments were carried out on the AFA steel at temperatures of 950-1150 ℃, strain rates of 0.01-10 s^-1 and true strains of 0.51-1.2 using a Gleeble-3500 thermal simulation tester to construct the instantonal equations and build up a thermal processing map. The results show that the rheological stress of the AFA steel gradually decreases with increasing deformation temperature at the same strain rate, and increases with increasing strain rate at the same deformation temperature. The linear correlation coefficient R² is 0.998 53 between predicted and actual stresses at a true strain of 0.69 (50% deformation). The thermal processing map shows that as the strain increases, the instability region of the AFA steel first decreases and then increases, concentrated in the low temperature region. The high-efficiency region becomes larger and the high efficiency region is concentrated at deformation temperatures between 1100 ℃ to 1150 ℃ with strain rates of 0.01 s^-1 to 0.1 s^-1, indicating that the AFA steel is suitable for thermal processing at high temperatures and low strain rates.

Key words: Alumina-forming austenitic steel, principal equation, thermal processing map, thermal deformation