A novel technique to measure the local mechanical properties of third generation advanced high strength steel resistance spot welds
Bibliographic record
Abstract
Distinct microstructures and mechanical properties are produced in resistance spot welds (RSW) of advanced high-strength steels (AHSS). The local mechanical properties within the fusion zone (FZ) and heat-affected zones (HAZ) govern the global failure response of RSW automotive structural assemblies in crash events. In this study, a novel experimental procedure was developed to characterize the local properties of RSW sub-regions using sub-size tensile and simple shear specimens extracted from the spot weld, with local strain measurement utilizing digital image correlation (DIC) techniques. The FZ properties were obtained using a simple shear test, while the HAZ properties were characterized using a tensile test containing a central RSW. A range of AHSS grades were considered to evaluate the proposed methodology, including 3rd Gen-980, 3rd Gen-1180, and press-hardened steel (PHS1500) with respective minimum ultimate tensile strengths of 980 MPa, 1180 MPa, and 1500 MPa. Strain localization occurred wherever the hardness was lowest such as in the subcritical heat-affected zone, with limited deformation in the harder regions, such as the upper-critical HAZ and FZ. The local stress-strain responses were then compared to a hardness scaling approach to estimate the tensile properties of RSW based on the local hardness in each zone. The hardness scaling method only appears to be a viable method if the microstructures across the weld have similar microconstituents in all sub-zones across the weld.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".