Mechanical Behavior of SS 304LN at High Strain Rates in Compression

Abstract

Stainless steel 304LN is used in various industries, where it is subjected to both static and dynamic loads. However, the austenitic phase of the steel is not stable, which upon loading partly transforms into martensite. Although the martensitic phase is stronger, the ductility of 304 series steels reduces with increasing volume fraction of the martensite. Besides, it is known that austenitic SS 304 grade steels show strain rate sensitivity and increased flow stress at high strain rates, similar to other FCC metals. In this work, quasi-static and dynamic compression experiments were performed on fully annealed SS 304LN between the strain rates of 0.001–4,800 s⁻¹ using an UTM and Kolsky bar setup, to understand their mechanical response over a wide range of strain rates. The experimental results showed that the flow stress increased with increasing accumulated strain and strain rate. The work hardening rate decreased with increasing strain rate and strain. To investigate strain rate sensitivity at constant structure of SS 304LN, interrupted rate jump experiments were performed with a change of strain rates under dynamic loading. It was observed that the constant structure rate sensitivity was much higher compared to that of the constant strain rate sensitivity.