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Vol.59, No.10, 683 ~ 692, 2021
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| Title |
| Development of 1.2 GPa Ferrite-based Lightweight Steels via Low-temperature Tempering |
| 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 |
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| 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) |
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| Key Words |
| ferrite-based lightweight steels, tempering, size-dependent partitioning, dislocation movement |
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