The influence of various welding parameters on porosity and underfill formation and magnesium loss during continuous wave Nd:YAG laser beam welding of thin plates of aluminum-magnesium Alloys 5182 and 5754 was investigated. The porosity within the welds was characterized by radiography, optical microscopy and SEM. The compositional change in the welds was measured by electron microprobe analysis. The experimental results showed that the instability of the keyhole was the dominant cause of macro-porosity formation during laser welding of thin plates of aluminum Alloys 5182 and 5754. Hydrogen did not play a significant role in porosity formation. Although underfill was commonly observed at the root of full-penetration welds, sharp or deep notches, which are harmful to the mechanical properties of the welds, were not present. Reduction in magnesium concentration was more pronounced during conduction mode welding. Welding in keyhole mode resulted in much larger weld pool and less pronounced composition change. The extent of defocusing of the laser beam greatly affected the stability of the keyhole, weld pool geometry, pore formation and composition change.
|Original language||English (US)|
|Journal||Welding Journal (Miami, Fla)|
|State||Published - Dec 1 1999|
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys