The Effects of Squarewave Polarity Parameters on Microalloyed Steel Charpy V-Notch Results
Bibliographic record
Abstract
The welding processes used to produce microalloyed steel pipe can result in mechanical property changes in the heat affected zone (HAZ) regions of seam and double joint (circumferential) welds. HAZ properties are controlled primarily by the microstructures resulting from the thermal history during welding. While multi-pass welds have successfully achieved CVN values greater than 66.4 ft-lbs (90 J) at the fusion line, this work explores the use of single-OD welds to achieve similar toughness values. Thus, single OD-pass submerged arc welding (SAW) test specimens were produced to examine the effect of electrode polarity on the HAZ Charpy V-notch (CVN) toughness. CVN results indicate that a DC+ lead, AC 50% trail tandem arc setting produces moderately improved CVN test HAZ results at −20°C compared with an AC 75% lead, AC 25% trail tandem arc setting. The difference is believed to be related to differences in effective heat input, though further investigation is required. The CVN specimens notched furthest from the fusion line gave the largest toughness result scatter. The elevated values are believed to be the result of greater lengths of the notch passing through unaffected base metal. Lower values (average CVN from 37 to 59 ft lbs (51 to 80 J)) were produced by notches located at the fusion line, which would pass through significant amounts of coarse grain heat affected zone (CGHAZ). The weld and base metal CVN results for both sets of welding conditions were comparable. Further optimization of welding parameters is required for a single pass weld procedure to achieve HAZ CVN values exceeding 66.4 ft-lbs (90 J) at the fusion line.
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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) | 0.002 | 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".