The kinetic of induced martensitic formation and its effect on forming limit curves in the AISI 304 stainless steel

The kinetic and microstructure characteristics of plastic induced martensite of 304 stainless steel were studied. X-ray dispersing energy diffraction coupled to metallographic analyses (SEM) was made on this material. In the experimental process, the specimens were deformed at room and lower temperatures. The role of induced martensite phase on hardening behavior was first discussed by kinetic laws. An analysis, which considers the type of loading, is then conducted in order to give more indications on this new phase transformation. The influence of this plastic induced martensite on the drawability of the 304 stainless steel when compared to 316 which is much more stable, were also been appreciated through forming limit curves (FLC). This appreciation was achieved experimentally using Nakazima test expansion and theoretically through an analytical modeling by Marciniak–Kuczynski method. Finally, validations of the identified hardening laws were made by metallographic observations.