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|1. (WO2018199145) HIGH-Mn STEEL AND PRODUCTION METHOD THEREFOR|
|Applicants:||JFE STEEL CORPORATION
|Title:||HIGH-Mn STEEL AND PRODUCTION METHOD THEREFOR|
The present invention proposes a method for imparting better ductility to high-Mn steel that has superior cryogenic toughness in both a welding heat-affected part and a matrix after being welded. This high-Mn steel has a component composition comprising, in mass%, 0.30-0.90% of C, 0.05-1.0% of Si, 15-30% of Mn, not more than 0.030% of P, not more than 0.0070% of S, 0.01-0.07% of Al, 0.5-7.0% of Cr, 0.0050-0.0500% of N, not more than 0.0050% of O, the respective contained amounts of Ti and Nb being at suppressed levels of less than 0.005%, with the remaining portion being Fe and unavoidable impurities, wherein the high-Mn steel has a microstructure including austenite as a matrix phase, the area fraction of non-metal inclusion in the microstructure is less than 5.0%, and the high-Mn steel has a yield strength of at least 400 MPa and an absorption energy (vE-196) of at least 100 J.