Low and Medium Carbon Advanced High-Strength Forging Steels for Automotive Applications
Abstract
:1. Introduction
- (I)
- (II)
- (III)
- Third generation AHSS: TRIP-aided steels with bainitic ferrite, bainitic ferrite–martensite, and martensite matrix structures (TBF, TBM, and TM steels, respectively) [11,12,13,14,15,16], quench and partitioning (Q&P) steels [7,8,17,18,19], nanostructured bainitic (Nano-B) steels (or carbide free bainitic steels) [3,4,7,8,20,21,22,23], dual-phase type and martensite type medium Mn (M-Mn) steels [7,8,24,25,26], and maraging-TRIP steels [7,27].
2. Classification of Hot-Forging Process for Low and Medium Carbon Steels
3. Conventional High-Strength Forging Steels; CFSs
3.1. Q&T Steels
3.2. PHFP-M Steels
3.3. Bainitic Steels
4. Advanced High-Strength Forging Steels; AFSs
4.1. TBF, One-Step Q&P, and Nano-B Steels (TIT > MS)
4.2. Two-Step Q&P (Mf < TQ < MS, TP > MS) and TBM Steels (Mf < TIT < MS)
4.3. TM and Martensite Type M-Mn Steels (TIT < Mf)
5. Summary
- (1)
- TBF, one-step Q&P, and Nano-B steels: refined bainitic ferrite matrix structure, refined prior austenitic grain, and a large amount of refined metastable retained austenite.
- (2)
- Two-step Q&P and TBM steels: refined dual-phase structure of soft martensite and bainitic ferrite, refined prior austenitic grain, and a large amount of refined metastable retained austenite.
- (3)
- TM and martensite type M-Mn steels: refined dual-phase structure of soft martensite and MA phase and refined prior austenitic grain.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Designation | Forging Temperature | Phase on Forging | Steel Type after Hot-Forging | ||
---|---|---|---|---|---|
Diffusion Transformation | Non-Diffusion and Diffusion Transformation | Non-Diffusion Transformation | |||
Conventional hot-forging | >TR | austenite | PHFP steel, PHFP-M steel, bainitic steel, TBF steel, one-step Q&P steel, Nano-B steel | Two-step Q&P steel, TBM steel | Q&T steel, TM steel, Martensite type M-Mn steel |
Controlled hot-forging | TR − Ac3 | austenite | |||
Ausforming | <Ac3 | metastable austenite |
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Sugimoto, K.-i.; Hojo, T.; Srivastava, A.K. Low and Medium Carbon Advanced High-Strength Forging Steels for Automotive Applications. Metals 2019, 9, 1263. https://doi.org/10.3390/met9121263
Sugimoto K-i, Hojo T, Srivastava AK. Low and Medium Carbon Advanced High-Strength Forging Steels for Automotive Applications. Metals. 2019; 9(12):1263. https://doi.org/10.3390/met9121263
Chicago/Turabian StyleSugimoto, Koh-ichi, Tomohiko Hojo, and Ashok Kumar Srivastava. 2019. "Low and Medium Carbon Advanced High-Strength Forging Steels for Automotive Applications" Metals 9, no. 12: 1263. https://doi.org/10.3390/met9121263