Effect of pin tool thread orientation on fatigue strength of friction stir welded AZ31B-H24 Mg butt joints
Bibliographic record
Abstract
The aim of this investigation was to evaluate the fatigue resistance of friction stir welded (FSWed) AZ31B-H24 Mg alloy butt joints with emphasis on the effect of pin tool thread orientation (right-hand thread (RHT) and left-hand thread (LHT)) in the clockwise rotation. The friction stir welding resulted in recrystallized grains in the stir zone (SZ) and thermomechanicallyaffected zone (TMAZ), and partially recrystallized grains in the heat-affected zone (HAZ), with the lowest hardness appeared in the SZ. The fatigue life after friction stir welding was observed to be lower at high stress amplitudes, but remained nearly the same at low stress amplitudes. Fatigue strength was higher in the FSWed joints made with the LHT pin tool than with the RHT pin tool due to the elimination of the welding defects near the bottom surface via a downward material flow. Fatigue fracture basically occurred at or near the boundary between TMAZ and SZ. Fatigue crack initiated from the specimen surface or near surface defects in the case of LHT pin tool, and from the welding defects near the bottom surface in the case of RHT pin tool. Crack propagation was characterized by the formation of fatigue striations.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".