Air-Hardening Die-Forged Con-Rods—Achievable Mechanical Properties of Bainitic and Martensitic Concepts
Abstract
:1. Introduction
2. Materials and Methods
3. Results
3.1. Microstructure
3.2. Fracture Surfaces
3.3. Mechanical Properties
4. Discussion
5. Conclusions
- The presented steels show good balances of strength and ductility in the air-hardened condition, which enables the substitution of other standard steel grades.
- The CO2-footprint of forged components can be reduced by lightweighting or shortening the heat treatment through the utilization of new air-hardening materials.
- The combination of impact toughness and yield strength is suitable for con-rod production in the case of the bainitic steels, while final confirmation has to be made for the martensitic steel.
- A comparison of the bainitic grades reveals that the 19MnCrMo7-6 steel achieves comparable strength but higher elongations and impact toughness than the 35MnCrB6-4 steel. The differences in mechanical properties can be explained by the differences in the bainite morphology.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Alloy | C * | Si | Mn | P | S * | Cr | Mo | Al | Nb | B | N |
---|---|---|---|---|---|---|---|---|---|---|---|
B1 | 0.34 | 0.19 | 1.61 | 0.009 | 0.006 | 0.80 | max. 0.30 | 0.027 | 0.002 | 0.0036 | 0.007 |
B2 | 0.20 | 0.26 | min. 1.50 | 0.010 | 0.007 | min. 1.40 | max. 0.40 | 0.023 | max. 0.060 | max. 0.003 | 0.019 |
max. 2.10 | max. 1.85 | ||||||||||
M | 0.15 | 0.50 | 3.90 | 0.004 | 0.002 | 0.10 | 0.24 | 0.52 | 0.030 | 0.0025 | 0.006 |
Scan-# | Fe | Mn | S | Al | Cr | N | Mg | Ca | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Signal | Signal | Signal | Signal | Signal | Signal | Signal | Signal | |||||||||
1 | 8.5 | 0.19 | 51.9 | 0.43 | 28.6 | 0.26 | - | - | 0.6 | 0.07 | - | - | - | - | 0.9 | 0.05 |
2 | 45.1 | 0.32 | 29.1 | 0.25 | 15.8 | 0.15 | - | - | 1.2 | 0.07 | - | - | - | - | - | - |
3 | 23.6 | 0.30 | 32.3 | 0.36 | 20.7 | 0.23 | 4.3 | 0.11 | - | - | 4.4 | 0.53 | 2.1 | - | 0.6 | 0.05 |
4 | 55.7 | 0.44 | 5.1 | 0.13 | 10.3 | 0.13 | - | - | - | - | - | - | 0.6 | 0.09 | 10.5 | 0.13 |
5 | 25.5 | 0.27 | 3.3 | 0.10 | 2.0 | 0.06 | 32.3 | 0.30 | - | - | 29.3 | 0.49 | 0.4 | 0.05 | 0.5 | 0.04 |
6 | 14.1 | 0.20 | 1.2 | 0.07 | 0.8 | 0.04 | 43.7 | 0.43 | - | - | 32.3 | 0.52 | - | - | 0.5 | 0.04 |
7 | 10.6 | 0.20 | 21.7 | 0.26 | 31.2 | 0.31 | 1.5 | 0.09 | - | - | - | - | 7.0 | 0.13 | 15.0 | 0.18 |
8 | 86.3 | 0.33 | 4.3 | 0.12 | - | - | 0.4 | 0.06 | 0.2 | 0.05 | - | - | - | - | - | - |
9 | 4.4 | 0.15 | 33.5 | 0.33 | 25.3 | 0.25 | 1.5 | 0.07 | - | - | - | - | 5.1 | 0.10 | 3.1 | 0.07 |
10 | 46.3 | 0.32 | 3.3 | 0.09 | 0.6 | 0.04 | 19.9 | 0.17 | - | - | - | - | - | - | - | - |
11 | 24.4 | 0.26 | 6.8 | 0.12 | 5.2 | 0.08 | 21.3 | 0.21 | - | - | 18.6 | 0.51 | 0.8 | 0.04 | 0.6 | 0.04 |
12 | 4.4 | 0.14 | 31.9 | 0.31 | 23.5 | 0.23 | 1.3 | 0.06 | - | - | - | - | 4.7 | 0.09 | 2.8 | 0.06 |
13 | 34.6 | 0.33 | 14.2 | 0.18 | 8.5 | 0.11 | 10.2 | 0.13 | - | - | 12.1 | 0.49 | 1.5 | 0.06 | 1.1 | 0.05 |
Alloy | YS | UTS | Au | At | CVNm | CVNc | Fmax | Hardness |
---|---|---|---|---|---|---|---|---|
[mPa] | [mPa] | [%] | [%] | [J] | [J] | [kN] | [HV30] | |
Q + T [7] | 959 | 1091 | 4.9 | 13.0 | — | — | — | — |
B1 | 732 ± 22 | 1114 ± 28 | 4.6 | 11.6 | 6 | 4.4 | 14.35 | 332 |
B2 | 721 ± 11 | 1055 ± 11 | 5.9 | 14.9 | 15 | 13.6 | 21.52 | 343 |
M | 847 ± 23 | 1341 ± 3 | 4.0 | 12.3 | 37 | 30.5 | 27.45 | 406 |
M + ba | 914 ± 25 | 1281 ± 1 | 4.0 | 12.7 | 44 | 36.3 | 27.55 | 372 |
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Gramlich, A.; Lange, R.; Zitz, U.; Büßenschütt, K. Air-Hardening Die-Forged Con-Rods—Achievable Mechanical Properties of Bainitic and Martensitic Concepts. Metals 2022, 12, 97. https://doi.org/10.3390/met12010097
Gramlich A, Lange R, Zitz U, Büßenschütt K. Air-Hardening Die-Forged Con-Rods—Achievable Mechanical Properties of Bainitic and Martensitic Concepts. Metals. 2022; 12(1):97. https://doi.org/10.3390/met12010097
Chicago/Turabian StyleGramlich, Alexander, Robert Lange, Udo Zitz, and Klaus Büßenschütt. 2022. "Air-Hardening Die-Forged Con-Rods—Achievable Mechanical Properties of Bainitic and Martensitic Concepts" Metals 12, no. 1: 97. https://doi.org/10.3390/met12010097