Correlation Between Microstructure and Hardness of the Weld HAZ in Grade 100 Microalloyed Steel
Bibliographic record
Abstract
The weld thermal cycle results in significant changes in microstructure and, consequently, mechanical properties of the weld heat affected zone (HAZ). In this paper, hardness variations across the HAZ and for different welding heat inputs (0.5–2.5 kJ/mm), obtained in a Grade 100 microalloyed steell, are explained based on the microstructural observations. Micro- and nano-hardness examination provided hardness profiles across the HAZ and nano-distribution of hardness in each HAZ sub-region, respectively. Optical microscopy and transmission electron microscopy (TEM) were used for evaluation of grain size, phase structure and precipitate type, shape and distribution. Both carbon replicas and thin foils (prepared by focused ion beam technique) were used for TEM. The fine-grained HAZ for all heat inputs was primarily composed of polygonal ferrite, with some regions of twinned martensite in the higher heat input (1.5 and 2.5 kJ/mm) samples. Twinned martensite regions were also identified in the coarse-grained HAZ of the 0.5 kJ/mm sample. Grain size changes were the major cause for the variation of hardness in the fine-grained HAZ; however, large packets of bainitic ferrite and martensite in the coarse-grained HAZ, with small ferrite/martensite laths, were responsible for the relative hardening in the coarse-grained HAZ.
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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".