Bibliographic record
Abstract
Abstract Much has been studied on the individual effects of creep and fatigue on alloy life. However, not much is known of the combined effects of these two mechanisms. Therefore, a study was put into place to determine the effects of dwell on fatigue life and deformation mechanisms, for IN617, a solid-solution strengthened Ni-base alloy used widely in the power generation and aerospace industries. Low cycle fatigue (LCF) tests were conducted from 649–982°C with either tensile or compressive dwell. Fracture surfaces of the test specimens as well as longitudinal and transverse sections were examined via scanning electron microscopy to determine the damage and failure mechanisms. Test results confirmed tensile dwell lives that were significantly lower than those seen in compressive dwell. The mechanics for the reduction in cyclic life for tensile dwell was attributed to creep damage accumulation at grain boundaries that led to widespread intergranular cracking and failure. Tensile dwell life reductions were largest in tests at moderate (649–760°C) temperatures. The failed specimens for this temperature range showed the most evidence of grain boundary cavitation and intergranular cracking. At higher test temperatures, the tensile dwell sensitivity for IN617 was significantly reduced or almost entirely eliminated at high temperatures (871–982°C). This was attributed to the lower stresses that developed at these temperatures for a given strain range. The LCF testing and subsequent analysis indicated that a substantial tensile stress during dwell time coupled with moderate temperatures, to allow for diffusion creep, lead to grain boundary damage that can reduce cyclic life.
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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".