Influence of Thermo-Mechanical Treatments on Structure and Mechanical Properties of High-Mn Steel

The aim of this paper is to determine the high-manganese austenite propensity to twinning induced by the cold working and its effect on structure and mechanical properties, and especially the strain energy per unit volume of new-developed high-manganese Fe – Mn – (Al, Si) investigated steel, containing about 24,5 % of manganese, 1% of silicon, 3 % of aluminium and microadditions Nb and Ti with various structures after their heat- and thermo-mechanical treatments. The new-developed high-manganese Fe – Mn – (Al, Si) steel provide an extensive potential for automotive industries through exhibiting the twinning induced plasticity (TWIP) mechanisms. TWIP steel not only show excellent strength, but also have excellent formability due to twinning, thereby leading to excellent combination of strength, ductility, and formability over conventional dual phase steels or transformation induced plasticity (TRIP) steels. Results obtained for high-manganese austenitic steel with the properly formed structure and properties in the thermo-mechanical processes indicate the possibility and purposefulness of their employment for constructional elements of vehicles, especially of the passenger cars to take advantage of the significant growth of their strain energy per unit volume which guarantee reserve of plasticity in the zones of controlled energy absorption during possible collision resulting from activation of twinning induced by the cold working as the fracture counteraction factor, which may result in significant growth of the passive safety of these vehicles' passengers.