Investigation of the Effect of Pulsing Shielding Gas in Arc Welding
Keywords:Pulsing Shielding Gas
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Industrial, Welding and Systems Engineering Honors Theses; 2006
Russian engineers have discovered a new method of delivering shielding gas for arc welding. This new method uses equipment known as the Gas PulserTM to deliver an alternating or “pulsing” supply of two pure shielding gases which are input, creating an alternating supply of shielding gas delivered through a single gas line as opposed to the old method of using premixed shielding gas. The goal of this new “pulsing” method is to create a superior method of protection for the molten weld pool. In using this new machine and the equipment at The Ohio State University Welding Engineering Laboratory at the Edison Joining Technology Center, an investigation is currently being carried out to examine the effects of gas pulsing on weld deposits. Pulsed pure Argon and CO2 shielding gases are being compared to mixed bottles of 90% Argon/10% CO2 and 75% Argon/25% CO2 to see the effects of arc performance. Gas metal arc welding (GMAW) is being used to weld a carbon steel T-joint located in the flat position. These T-joints are then cross sectioned and the weld profiles are examined in comparison to the arc performance caused by the pulsing effect. The welding arc produced during the pulsing of the shielding gas produces an arc different from any other welding procedure resulting in a varying arc length and transfer as the two gases are pulsed. The arc experiences switching from spray transfer to short-circuiting within the welding puddle. This type of arc manipulation could be the primary cause for positive effects such as less spatter and porosity during welding. In addition to these advantages, mixed shielding gas weld profiles have been compared to the pulsed shielding gases weld profiles using lower amounts of Argon shielding gas. If similar weld profiles can be accomplished by welding with less Argon and more CO2, with the use of two pure gas bottles during the pulsing procedure, a great cost savings in shielding gas costs could be implemented.