27. TWIP Mechanism in High-Mn Austenitic Steels and Its Effect on Steels Properties

The objective of this paper is to define the high-Mn austenitic steels susceptibility to twinning induced by the cold working and influence of it on microstructure and mechanical and plastic properties, and primarily the strain energy per unit volume of newly developed high-Mn austenitic TWIP (Twinning Induced Plasticity)-type steel which contains about 25% of Mn; 1% of Si and 3% of Al. TWIP steels not only present excellent strength, but also have outstanding formability due to twinning, through leading to an exceptional combination of strength, ductility and formability over conventional dual-phase steels. The essence of the investigation concerns the analysis of the importance of microstructure evolution during plastic deformation in ambient temperature. The microstructure of investigated high-Mn steel was determined in metallographic studies using optical microscope and also scanning and high-resolution transmission electron microscopes (HRTEM). Results achieved under static conditions for newly developed advanced high-Mn steel show the opportunity and purposefulness of their use for constructional elements of a body car, especially of the cars’ passenger to take advantage of the meaningful growth of their strain energy per unit volume. It can guarantee a reserve of plasticity in the specially constructed zones and thereby control energy absorption during a potential car accident by activation of twinning induced by cold working. It can also lead to significant growth of the passive safety of those cars’ passengers.