Gas Metal Arc welding (GMAW) with alternating shielding gas is a new technology that supplies two different shielding gases to the torch alternatingly for protecting the arc and weld pool from atmospheric contamination. This new technology is capable of giving better weld quality and high efficiency. The improved weld quality is attributed to the periodically varying arc and weld-pool dynamics caused by the differing thermo-physical properties of the shielding gases supplied alternatingly. In this study the effect of alternating shielding gases on the fusion characteristics have been investigated using the gas alternator (WRI Patented) developed by WRI. The investigation has been carried out on carbon steel using CO{sub}2 and argon as the alternating shielding gases. The modes of metal transfer studied include short circuit, Globular and Spray. The alternating supply of shielding gases in the weld zone produces an effect similar to pulsed GMAW but dynamically more superior. The results of this study show that GMAW process requires higher gas pulsing frequency due to the higher welding speed associated with this process. The spatter level is found to be very low as compared to 100% CO{sub}2 shielding gas. Low frequency gas pulsing results in uneven bead profile. Whereas high frequency gas pulsing produces more uniform bead profile with deep penetration and smooth wetting angle.
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