Dissimilar ultrasonic spot welding of AA6016 alloy-to-DP800 steel: The role of a novel AlSi(Fe) PVD coating
Bibliographic record
Abstract
Lightweighting in the automotive industry often involves joining dissimilar materials, while ensuring the safety and durability of load-bearing components. However, the joining of dissimilar materials presents significant challenges due to differences in their physical and chemical properties. In this study, a novel AlSi(Fe) physical vapor deposition (PVD) coating was applied on DP800 steel to enhance its compatibility with AA6016 aluminum alloy during solid-state ultrasonic spot welding (USW). The AA6016-to-coated DP800 steel joints, fabricated at welding energies around 1250 J, surpassed the tensile lap shear load requirements specified in the AWS D17.2 standard. The presence of the PVD coating not only enhanced the tensile lap shear strength by 23 % (i.e., from 69 MPa to 85 MPa), but also reduced the welding energy required to achieve optimal joint performance by 37.5 % (i.e., from 2000 J to 1250 J). This reduction in energy consumption further contributed to improved welding efficiency. The AA6016-to-uncoated DP800 steel joints at a welding energy of 2000 J exhibited button pullout failure under tensile loading and high-stress cyclic loading, largely due to excessive thinning of the AA6016 alloy. In contrast, the AA6016-to-coated DP800 steel joints welded at 500 J showed adhesive failure caused by defects at the weld interface. However, at a welding energy of 1250 J, these joints demonstrated superior intermixing between the Al sub-layer of PVD coating and the AA6016 alloy, resulting in a combination of cohesive and adhesive failure modes. The findings reveal the effectiveness of the AlSi(Fe) PVD coating in improving the mechanical properties of the joints while enhancing the energy efficiency of the welding process. • A novel AlSi(Fe) PVD coating with nearly pure Al enables AA6016-to-DP800 welding. • The outer Al sub-layer enhances thermophysical similarity between Al and steel. • Joints made at ∼1250 J without intermetallic formation exceed AWS D17.2 standards. • Optimal joints show mixed failure modes and superior coating-AA6016 intermixing. • Effect of PVD coating on the transition of failure mechanisms is explicated.
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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 | 0.000 |
| 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) | 0.001 | 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".