| Title |
Development of 1.2 GPa Ferrite-based Lightweight Steels via Low-temperature Tempering |
| Authors |
배효주(Hyo Ju Bae); 고광규(Kwang Kyu Ko); 박형석(Hyoung Seok Park); 정재석(Jae Seok Jeong); 김정기(Jung Gi Kim); 성효경(Hyokyung Sung); 설재복(Jae Bok Seol) |
| DOI |
https://doi.org/10.3365/KJMM.2021.59.10.683 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
ferrite-based lightweight steels; tempering; size-dependent partitioning; dislocation movement |
| Abstract |
Previously reported low-Mn ferritic-based lightweight steels are potential candidates for industrial applications, however, they typically exhibit lower strength, with < 1 GPa and lower strength-ductility balance, than medium- and high-Mn austenitic lightweight steels. Herein, we introduce a low-temperature tempering-induced partitioning (LTP) treatment that avoids the strength-ductility dilemma of low-Mn ferritic-based steels. When the LTP process was performed at 330 ℃ for 665 s, the strength of typical ferritic base Fe-2.8Mn5.7Al0.3C (wt%) steel with heterogeneously sized metastable austenite grains embedded in a ferrite matrix, exceeded 1.1 GPa. Notably, the increased strength-ductility balance of the LTP-processed ferritic steel was comparable to that of the high-Mn based austenitic lightweight steel series. Using microscale to nearatomic scale characterization we found that the simultaneous improvement in strength and total elongation could be attributed to size-dependent dislocation movement, and controlled deformation-induced martensitic transformation.(Received May 14 2021; Accepted July 5, 2021) |