Effect of strain rate on martensitic transformation behavior of 304 austenitic stainless steel: experimental characterization and constitutive modeling

This study investigated the effect of strain rate (10⁻⁴ to 340 s⁻¹) on the martensitic transformation behavior of 304 austenitic stainless steel through quasi-static and dynamic tensile tests. A magnetic balance-based device was employed for precise, localized measurement of the martensite volume fraction. A strain-limiting device was utilized to control the single strain increment to less than 5% during dynamic testing, thereby eliminating the influence of adiabatic heating. The results demonstrate a significant inhibitory effect of strain rate on the martensitic transformation, with the martensite volume fraction exhibiting a monotonic decreasing trend as the strain rate increases. Furthermore, the martensite volume fraction versus strain curve displays a characteristic S-shape, indicating that the transformation rate follows a pattern of “gradual increase, sharp acceleration, and gradual deceleration” with increasing strain. Based on the experimental data, a martensitic transformation model incorporating the strain rate effect was developed. This model can predict the austenite-to-martensite transformation behavior across a wide range of strain rates and accurately reproduces the typical S-shaped evolution of the transformation with strain. Electron backscatter diffraction (EBSD) analysis indicates that with increasing strain rate, the number of orientations involved in martensitic transformation decreases, and strain rate exerts an inhibitory effect on the martensitic transformation behavior of 304 ASS.