Nd:YAG Laser Welding of Magnesium Alloy Castings
Bibliographic record
Abstract
Abstract A continuous wave (CW) 4 kW Nd:YAG laser system was used to weld 2-3 mm butt joints of sand-cast ZE41A-T5 magnesium alloy at a power of 2.5 or 3.5 kW, welding speed of 6.0 m/min anddefocusing distance from 0 to +3 mm for the material on the as-cast surface conditions. Sound joints with good surface quality,minor pores and microcracks can be obtained using strictly controlled laser welding parameters. Introduction Metal magnesium is nearly an inexhaustible resource on theearth’s crust and in seawater. Moreover, magnesium alloys have very attractive properties such as low density, excellent specificstrength, good thermal conductivity, excellent sound damping capabilities (good impact resistance and noise absorption), good castability (especially for high pressure die-casting), excellentmachinability, good electromagnetic interference shieldingcapability and recyclability [1]. Magnesium alloys, therefore, havequickly growing applications in aerospace, aircraft, automotive,electronics and other industries. More interests have been concentrated on joining magnesium alloys to themselves or todissimilar materials such as aluminum or steel [2]. Up to datethere has been a lack of effective and efficient welding techniquesfor magnesium alloys. Conventionally metal inert gas (MIG) andtungsten inert gas (TIG) arc welding processes are the two main methods for magnesium alloys [2]. However, high heat-input arcwelding processes cause the variation in metallurgical structures,large heat affected zone (HAZ) and fusion zone (FZ), highshrinkage, evaporation and loss of some alloying elements, high residual stress and weld distortion as well as low welding speed. For thick or highly constrained work-pieces, preheating is alsoneeded. Compared with arc welding, high energy-density laserwelding has the potential to become an important joiningtechnique for magnesium alloys due to low and precise heat input,small HAZ, deep and narrow FZ, high welding speed and productivity, low residual stress and weld distortion, possible elimination of pre- and post-weld heat treatment, highly accuratejoint sizes, great process flexibility and reliability. Up to date onlylimited work has been conducted on the welding of castmagnesium alloys using laser beams [3, 4]. The main objective ofthe present study was to investigate the laser weldability ofZE41A-T5 alloy and develop a reliable welding and repairprocess for sand-cast aerospace components. This paper reportson the influence of defocusing distance and use of filler wire onthe laser welding of 2-3 mm ZE41A-T5 sand castings for thematerial on the as-cast surface conditions, using a CW 4 kWNd:YAG (neodymium-doped yttrium aluminum garnet) laserwelding system.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.007 | 0.002 |
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".