Metallurgical Phase Transformation and Behavior of Steels Under Impact Loading

This study deals with the mechanical behavior of the austenitic stainless steel, AISI 304, under quasi-static and impact loadings. In particular, the evolution of the transformation-induced plasticity (TRIP) is investigated. Several compression tests have been performed at various strain rates under both static and impact conditions (crash tests). In order to show the influence of the strain rate on the phase transformation, the microstructures of as-received and deformed specimens have been observed with a scanning electron microscope. Then, the newly formed ferromagnetic martensitic phase is analyzed with the help of the vibrating sample magnetic (VSM) method and by X-ray diffraction (XRD). The results obtained from the mechanical testing indicate that the TRIP effect is actually occurring since a significant change of the curve slope is visible during the hardening regime in the stress–strain curve. The VSM and XRD techniques, on the other hand, show that the proportion of the martensitic phase is reduced when the strain rate is increased. The quantity of martensite formed is greater when quasi-static loadings are applied to the material.