Austenite Reversion Tempering-Annealing of 4 wt.% Manganese Steels for Automotive Forging Application
Abstract
:1. Introduction
2. Materials and Methods
3. Results
3.1. Mechanical Properties
3.2. Microstructure
4. Discussion
5. Conclusions
- Air-hardening martensitic forging steels develop high ultimate tensile strengths from 1370 –1510 but low room temperature Charpy impact energy of below 20 .
- Microalloying with boron and molybdenum only slightly increases the Charpy impact energy after air cooling.
- Through ART-annealing, finely distributed retained austenite islands are obtained that can provide Charpy impact energy values above 80 .
- Obviously, there exist an optimum austenite content as by austenite fractions above about 10 vol.% Charpy impact energy decreases again together with the development of serrated plastic flow behavior in the tensile test.
- The Charpy impact energy improvement is due to the occurrence of a continuous TRIP effect and less Mn segregation at grain boundaries.
Author Contributions
Funding
Conflicts of Interest
Abbreviations
AC + ART | Air cooling and austenite reversion tempering |
Q + T | Quenching and tempering |
Q + P | Quenching and partitioning |
ART | Austenite reverted transformation |
EDS | Energy dispersive X-ray spectroscopy |
PHFP | Precipitation hardening ferritic pearlitic |
EBSD | Electron backscattering diffraction |
SE | Secondary electron |
SEM | Scanning electron microscopy |
LOM | Light optical microscopy |
HDB | High ductile bainite |
LHD | Air hardening ductile (German abbreviation) |
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Alloy | C * | Si | Mn | P | S * | Al | Mo | Ti | Nb | B | N |
---|---|---|---|---|---|---|---|---|---|---|---|
L1 | 0.19 | 0 50 | 4.02 | 0.008 | 0.011 | 0.031 | 0.02 | 0.020 | 0.035 | 0.0016 | 0.011 |
L2 | 0.17 | 0.50 | 3.99 | 0.010 | 0.009 | 0.025 | 0.02 | 0.020 | 0.033 | 0.0057 | 0.010 |
L3 | 0.15 | 0.49 | 4.02 | 0.011 | 0.009 | 0.027 | 0.20 | <0.003 | 0.035 | <0.0005 | 0.010 |
Alloy | As-Forged | 600 C | 625 C | 650 C | 675 C |
---|---|---|---|---|---|
L1 | 15 | 23 | 28 | 85 | 51 |
L2 | 25 | 22 | 34 | 82 | 53 |
L3 | 16 | 22 | 35 | 101 | 62 |
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Gramlich, A.; Emmrich, R.; Bleck, W. Austenite Reversion Tempering-Annealing of 4 wt.% Manganese Steels for Automotive Forging Application. Metals 2019, 9, 575. https://doi.org/10.3390/met9050575
Gramlich A, Emmrich R, Bleck W. Austenite Reversion Tempering-Annealing of 4 wt.% Manganese Steels for Automotive Forging Application. Metals. 2019; 9(5):575. https://doi.org/10.3390/met9050575
Chicago/Turabian StyleGramlich, Alexander, Robin Emmrich, and Wolfgang Bleck. 2019. "Austenite Reversion Tempering-Annealing of 4 wt.% Manganese Steels for Automotive Forging Application" Metals 9, no. 5: 575. https://doi.org/10.3390/met9050575