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Effects of Shielding Gas Parameters on Droplet Transfer and Bead Profile Prepared by CO2 Laser-MAG Hybrid Welding
S-Y. Liu, Y. Shi, H. Zhang, F-D. Liu and J. Liu

The variations in arc characteristics, stability of the hybrid welding process and behaviour of the droplet transfer with different shielding gas parameters have been studied by means of high speed video photography during CO2 laser-metal active gas (MAG) hybrid welding of 5 mm thick high strength steel plates with an austenitic stainless steel filler wire. The results indicate that the shielding gas is critical to the process stability, droplet transfer mode and dimensional characteristics of weld bead for when CO2 laser-MAG hybrid welding. The behaviour of the droplet transfer noted by the droplet diameter and detachment velocity was found to be related to gas flow rate. When the gas flow rate was increased to a critical value, the hybrid welding characteristic was changed from stable hybrid welding to unstable hybrid welding, and the frequency of droplet transfer decrease and the droplet diameter increase significantly.

Keywords: CO2 laser welding, metal active gas (MAG) welding, shielding gas, high speed video photography, droplet transfer, weld geometry

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