| About this Abstract |
| Meeting |
2025 TMS Annual Meeting & Exhibition
|
| Symposium
|
Thermodynamics and Phase Diagrams Applied to Materials Design and Processing: An FMD/SMD Symposium Honoring Rainer Schmid-Fetzer
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| Presentation Title |
CALPHAD-assisted process optimization for free-cutting steels |
| Author(s) |
Shih-kang Lin |
| On-Site Speaker (Planned) |
Shih-kang Lin |
| Abstract Scope |
Steels with good machinability are required for machining efficiency in industry. The manganese sulfide (MnS) inclusions in free-cutting steels act as stress raisers, lowering the shear strength of steel such that the cutting resistance is reduced. Because the morphology of MnS critically determines the machinability of steels, the reactions involving the formation of MnS during solidification need to be carefully assessed, especially about whether they are eutectic or monotectic reactions. Here we established the relationships between alloying elements and solidified microstructures by utilizing both the CALPHAD-type thermodynamic modeling and high-temperature experiments at 1600 °C. Among 22 candidate alloying elements, oxygen is identified as a super-strong monotectic-stabilizer, and the addition of oxygen can drastically promote the formation of monotectic-type MnS, which is desirable for free-cutting steels. With the combined efforts of thermodynamic calculations and high-temperature experiments, the morphology, size, and uniformity of MnS inclusions can be optimized for better free-cutting steels. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Computational Materials Science & Engineering, Solidification, Iron and Steel |