Effect of Rolling after Heat Treatment on Hydrogen Embrittlement Susceptibility for High Strength Steel Fasteners
Bibliographic record
Abstract
ABSTRACT Steel fasteners comprising two different metallurgical structures were investigated for hydrogen embrittlement (HE) susceptibility by incremental step load testing. The metallurgical structures examined consisted of tempered martensite obtained by quenching and tempering and lower bainite obtained by austempering. It has been shown that lower bainite exhibits marginally lower HE susceptibility when tested under moderate hydrogen charging conditions (e.g., −1.0 V). At the most severe hydrogen charging potential of −1.2 V, both microstructures are equally embrittled. The current paper examines the effect of the sequence of the fabrication process, specifically the effect of rolling the threads before and after heat treatment (i.e., quenching and tempering or austempering). The results show irrespective of the metallurgical structure, rolling the threads after heat treatment causes a significant decrease in HE susceptibility. These findings are attributed to the presence of high dislocation density when thread rolling is performed on hardened parts as a final manufacturing step.
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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".