Crack Initiation and Early Propagation of X70 Steel in Simulated Near-Neutral pH Groundwater
Bibliographic record
Abstract
The near-neutral pH environmentally assisted cracking (EAC) initiation and propagation behavior of X70 pipeline steel was investigated in NS4 solution deaerated with N2/5% carbon dioxide (CO2) under the low-frequency cyclic load. The test results show that an increase in the applied stress level promotes the crack initiation. Based on the crack initiation sites, the cracks are divided into two types, pit cracks and non-pit cracks. Non-pit crack initiation is found to be the dominative cracking mechanism on the original external pipe surface, but as the tests progress, the contribution of pit cracks becomes significantly pronounced. The pits acted as the crack initiation sites are related to the localized dissolution at/around the nonmetallic inclusions. Therefore, it is expected that the EAC initiation resistance of steel can be improved by reducing the inclusion content in the steel. The crack propagation rate is found to be essentially independent of the applied stress level. By comparing the crack initiation lifetime of the X70 steel to the test data of X65 steel reported in the literature, it is found that X70 steel is more resistant to the EAC than the X65, owing to the effect of microstructure.
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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 | 0.001 |
| 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".