Influence of high strain rates on the structure and mechanical properties of high‐manganes austenitic TWIP‐type steel

Abstract

The purpose of this paper is to determine the influence of high strain rates on the structure and mechanical properties of high‐Mn austenitic TWIP steel. Low and high strain deformation rates in the range of 0.001 s–1 to 1000 s–1 have a significant effect on the forming of the structure and mechanical properties of high‐manganese austenitic steel. Also, the strain energy per unit volume of advanced high‐Mn TWIP steel containing Mn, Al and SI, with Nb and Ti microadditions, increases considerably in dynamic conditions. This group of steels not only shows excellent strength, but also excellent formability due to twinning, thereby leading to a unique combination of strength, ductility and formability when compared with conventional dual phase steels or transformation induced plasticity TRIP steels. The microstructure of the investigated steel was determined in metallographic investigations using scanning and high‐resolution transmission electron microscopies (HRTEM). Results obtained in static and dynamic conditions for new developed high‐manganese austenitic steel indicate their possible employment for the constructional elements of vehicles, especially passenger cars, to take advantage of the significant growth of their strain energy per unit volume. This guarantees a reserve of plasticity in the zones of controlled energy absorption during possible collision resulting from the activation of twinning induced by cold working, which may lead to a significant growth of the passive safety of these vehicles' passengers.