304 stainless steel (SS 304) with its superior high-temperature resistance has been highly sought after. To explore the rheological behavior of SS 304 at high-temperature conditions, isothermal hot compression tests were conducted using the Gleeble-3800 thermal simulation machine under temperatures of 800–1200 °C, strain rates 0.011 to 11 \({s}^{-1}\) , and a strain of 60%. The Johnson–Cook (JC) constitutive model was constructed and optimized based on the experimental data. By introducing coupled strain, strain rate, and temperature effects, a more precise constitutive equation was established. The result indicates that the optimized JC model predicts the rheological behavior of SS 304 more accurately, as evidenced by a correlation coefficient (Rco) value of 0.9884 and an average absolute relative error (AARE) of 8.452%, indicating high prediction accuracy. ABAQUS further verified the optimized model. This study has important theoretical value to the hot processing of SS 304 and helps to ensure accurate calculation of the stress response of the material at high-temperature conditions, which will aid in optimizing process parameters and optimizing the performance of the material. Novelty of the research is a modified Johnson–Cook model incorporating coupled strain, strain rate, and temperature effects was developed and validated to accurately predict the high-temperature rheological behavior of SS 304, achieving high predictive accuracy (R = 0.9884, AARE = 8.452%).
