Transient Local Melting in Al 7075-T6 Friction Stir Spot Welds
Bibliographic record
Abstract
Transient local melting can account for the remarkable decrease in the strain rate when the tool rotational speed, heating rate and cycle time produce temperatures exceeding the 475 °C in Al 7075-T6 spot welds. The calculated strain rate is about 20 s-1 in Al 7075-T6 spot welds produced using tool rotational speeds from 1500 RPM to 3000 RPM and dwell time of 4 s. However, the peak temperature is less than less than 475 °C when a low tool rotational speed setting (1000 RPM) is used; transient local melting and tool slippage are precluded and the calculated strain rate is high (about 650 s-1). It is proposed that transient local melted films directly influence formation of the stir zone microstructure in Al 7075- T6 spot welds. It is suggested that the stir zone microstructure in spot welds made using high tool rotational speed settings are determined by a combination of grain boundary sliding and the limitation of cavity interlinkages when transient local melted films form.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".