Abstract
The presence of lubricants on the surface of sheets favors the formation of pores in laser welded seams. This formation process was investigated by means of high-speed X-ray imaging of the full penetration laser beam welding process of two AA6016 aluminum sheets in overlap configuration. The measurement of the growth velocity of the bubbles indicated their sudden growth once they started to form. Further analysis of the X-ray images identified the point of origin of the pores: a few millimeters behind the capillary between the two aluminum sheets. The study shows that the lubricant does not affect the stability of the capillary, which evidences that the formation of these pores is not caused by the fluctuations of the capillary. These results explain for the first time why pore formation cannot be avoided by process strategies, which stabilize the capillary, when welding uncleaned sheets.
Highlights
Pores are a fatal defect in welding, as they reduce the strength of the joint
Pores result from instabilities of the capillary [1,2,3,4,5,6]
It has yet to be proven whether the formation of porosity of the three analyzed welds, while the length of the error bars represents the range between pores during laser beam welding of pre-lube-coated sheets results directly from the evaporation of the minimum and maximum measured values
Summary
Pores are a fatal defect in welding, as they reduce the strength of the joint. During laser beam welding, pores result from instabilities of the capillary [1,2,3,4,5,6]. It has yet to be proven whether the formation of porosity of the three analyzed welds, while the length of the error bars represents the range between pores during laser beam welding of pre-lube-coated sheets results directly from the evaporation of the minimum and maximum measured values. 2. Materials and Methods pores during laser beam welding of pre-lube-coated sheets results directly from the evaporation of. X-ray video of the pore formation process during a full penetration laser welding welding in two uncleaned AA6016 sheets, which is added in the Supplementary Materials. 2. Single frame of anofX-ray video of the formation process during welding in overlap configuration of uncleaned. 500 μm, configuration of uncleaned AA6016 sheets with a feed rate of 12 m/min, a beam diameter of 500 μm, a laser power.
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