Experimental and computational studies on hot cracking in single laser tracks of aluminium alloy AA2024 and related implications for laser powder bed fusion
Bibliographic record
Abstract
Laser powder bed fusion of high-strength aluminium alloys remains challenging due to the formation of hot cracks during the printing process. Hot cracking is a complex phenomenon involving a complex thermo-mechanical and metallurgical interplay. Such relationship needs to be fully understood to reap the benefits of advanced laser modulation (temporal and spatial) capabilities, now becoming available in PBF-LB. To this end, we explore the formation of hot cracks in single tracks produced using a simple spatial–temporal laser modulation characterised by laser pulses of various distance. The formation of cracks is then rationalised by physical and numerical modelling using multi-physics CFD simulation. We demonstrate that the area of the mushy zone at the back of the moving melt pool, dynamically contracts and expands according to the laser temporal regimes and find maxima in correspondence to the largest laser pulse distance and the time steps between exposures. By then analysing in detail in the crack observed in the printed parts fabricated with the same laser modulation, it is possible to conclude that the mechanisms leading to hot cracks in these specimens is analogous. In turn, the insights on single tracks can be extended, for the most part, to the case of bulk specimens. Nevertheless, printed specimens appear to be more sensitive to the erratic movement of the melt pool, due to the presence of a larger number of highly energetical grain boundaries and unintended microstructural defects (voids and inclusions), from which cracks can nucleate.
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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 | 0.000 |
| 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".