Enhancing strength and cryogenic toughness of high manganese TWIP steel plate by double strengthened structure design

There exists a technical difficulty in strengthening high manganese austenitic steel due to its face centered cubic crystal structure, especially considering its application potential in liquefied natural gas (LNG) tank building. In the present work, a novel process was utilized in high manganese austenitic steel plate and the steel with double strengthened structure comprising softened and hardened structures. We found that the combination of strength and cryogenic toughness could be achieved by double strengthened structure design. This double strengthened structure was fabricated by non-crystallization hot-rolling followed by being further treated at 900 degrees C for 600 s. The volume fraction of hardened structure is around 24%. Compared with full softened structure, the yield strength of the steel with double strengthened structure is increased by 86 MPa, and its cryogenic impact energy (196 degrees C) is only decreased by 17 J. The yield strength and cryogenic impacted energy (196 degrees C) reach 485 MPa and 123 J, respectively.