In-situ quantification and density functional theory elucidation of phase transformation in carbon steel during quenching and partitioning
Bibliographic record
Abstract
Phase transformation in low alloyed Fe-C steels during quenching and partitioning (Q&P), though authentically attributed to carbon diffusion, is scarcely quantified experimentally in terms of microstructural evolution and lack of fundamental backing at a quantum mechanics level. Herein, we report on a combined in-situ high energy synchrotron X-ray diffraction and density functional theory (DFT) study to unveil the physical mechanism of phase transformation in a Q&P processed advanced Fe-C steel. Beside a small fraction of bainite, a low air-quenching rate of ∼6 °C/s in the Ms to quenching temperature range leads to carbon enrichment into the untransformed austenite, which simultaneously turns up with the later stage of martensitic transformation at the existing austenite/martensite interfaces. The resulting transformations are ascertained by DFT results and attributed to a second energy barrier in ferrite/martensite facilitation to carbon diffusion to austenite at elevated temperatures, along with the well-known carbon solubility difference/equilibrium in austenite and martensite. The development of cubic martensite in the carbon steel is theoretically elucidated and attributed to more probable hopping sites and diffusion paths of carbon in the ferrite/martensite than in the austenite.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".