5th International High Manganese Steel Conference - HMNS 2022

In order to reduce the vehicles weight constructors are focusing on stronger or lighter materials.
High Mn lightweight steels could be a response to both demands due to high mechanical properties (Yield Strength up to almost 1000 MPa) and low density (15% lower than a standard Hadfield steel and 16% lower than a typical stainless austenitic steel like AISI 306L).
Lightweight steels undergo thermal treatments to exploit precipitation hardening given by κ-carbide formation which, depending on the precipitation site, can give very different mechanical strengthening effect and affect differently the ductility and toughness of the material.
In this work, the effect of different thermal treatments on the microstructure and mechanical properties of a cold rolled austenitic high Mn lightweight steel has been investigated.
Material has been cold rolled from the “as Hot Rolled” condition with a thickness reduction of 80%. Then, after thermal treatments the material characterization has been carried out focusing on the ongoing recrystallization, the κ-carbide precipitation or the coexistence of both transformations.
Material has been solubilized and aged or directly aged with two different temperatures and different holding time (550°C and 600°C for 30min, 1h, 1.5h and 8h). Even if the temperatures of the thermal treatments are very close the microstructure and the mechanical properties appear to be very different.
Peculiar microstructure and non-equilibrium phases have been observed and analysed and astonishing mechanical properties has been observed.