304 stainless austenitic steel (AISI 304) is renowned for its high temperature resistance and has been the subject of considerable research. To explore its rheological behavior at high temperature, isothermal hot compression experiments were conducted on the Gleeble-3800 thermal simulator at temperatures of 800–1200 °C, strain rates of 0.011–11 \({s}^{-1}\) , and a total strain of 60%. From the experimental data, a Johnson–Cook (JC) constitutive model was formulated and further optimized. The optimized model considers the combined effect of strain, strain rate, and temperature, resulting in a more precise constitutive equation. The enhanced JC model had excellent predictive power, with a correlation coefficient (Rco) of 0.9884 and an average absolute relative error (AARE) of 8.42%. ABAQUS simulations for verification confirmed the model to be valid. This study offers valuable theoretical information for the hot working of SS 304, enabling more precise predictions of stress behavior at high temperature and easier optimization of processing parameters and overall material behavior. Also, deformation of metastable austenitic stainless steel at temperatures below the Md point leads to the transformation of austenite into martensite. This study investigates how prior deformation, conducted at temperatures both below and above Md, affects the dynamic tensile behavior of AISI 304 stainless steel. Pre-deformation at 25 °C (below Md), as well as at elevated temperatures of 200 °C and 300 °C (above Md), enhances both the yield strength and ultimate tensile strength of the material. Notably, prior deformation at 25 °C to a small equivalent strain (< 0.03) results in significant improvements in strength (22%) and ductility (21–37%) during subsequent high strain-rate tensile loading at 200 and 300 s⁻1. The evolution of local strain fields and strain rates is analyzed using digital image correlation. Additionally, the development of localized necking is investigated through in-situ high-speed camera imaging.
