New shielding gas mixture for laser conduction welding of aluminum with a filler wire

2021 
It is common to use argon as the shielding gas for laser conduction welding of thin aluminum parts with a filler wire in the automotive industry. However, defects such as skips (i.e., discontinuities), holes in the weld, or a rough weld surface are commonly found when using argon as a shielding gas due to poor wettability. A new shielding gas mixture was developed in this study. With the addition of small amounts of active gases to an argon-based mixture, the wettability of the weld pool was significantly improved, yielding decreases in defectivity, improved penetration of the weldment, as well as a more stable welding process. The developed shielding gas mixtures could improve weld quality when compared to pure argon in laser wire conduction welding of different types of aluminum alloys in coach joint configuration. Energy dispersive spectroscopy (EDS) and wavelength dispersive spectroscopy (WDS) were used to detect the nitrogen and oxygen concentrations in the weld. The results show there is no noticeable increase in the oxygen or nitrogen concentration in the weld zone compared to the base metal when using the developed gas mixtures as shielding gas. Rising displacement testing was performed, it is shown that the weld strength obtained with the developed shielding gas mixtures is no less than that obtained with argon.
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