Excellent total Mechanical-Properties-Balance of 5% Mn, 30000 MPa% Steel

An experiment has been conducted to demonstrate the excellent total mechanical properties of steel, basically TS×TE (tensile strength and total elongation). A composition of steel used in this study was 0.10C-5.02Mn-1.96Si. The 20 kg ingot was prepared by vacuum melting and casting, using high purity electrically-purified Fe, Mn, and Si. For dc-oxidation, both C dc-oxidation and Al dc-oxidation were used sequentially. Oxygen content was eventually controlled to be in the level of below 20 ppm. A 38 mm square cross sectional rod was prepared by forging after soaking at 1200°C for 3600 s from this ingot. The forging was conducted with 75% area reduction followed by air cooling with a cooling rate of about 0.5 K/s. Dilatation curves are almost same regardless of cooling rates from 0.5 K/s to 67 K/s, suggesting that transformation temperature are almost same. By comparing the TS-TE balance of F, FT, WR and TRIP microstructures based on the same high Mn composition, it is found that sample F has more excellent balance properties.