TIG Welding: How Does AC Clean Oxide Layer?

[patshek]

Hello,
I know AC is used for welding of Aluminum or materials that have oxide layer on the surface
Books also tell me that the oxide layer is cleaned by AC
However, what is the exact mechanism of this cleaning action? Besides, where does the oxide gone? Vaporized? Dissolved?
Thanks

 

[nucleus]

There are other metals that have oxide layers that are not welded with AC. The oxide layer on Al melts at a higher temperature than the base metal and should be removed mechanically or chemically before welding. Lincoln has a good site on welding:
http://www.lincolnelectric.com/knowledge/articles/content/alum.asp

 

[oswaler]

for your question! TIG welding, also known as gas tungsten arc welding, is a welding process that uses a non-consumable tungsten electrode to create the arc and heat required for fusing metal together. In TIG welding, alternating current (AC) is used to clean the oxide layer on the surface of metals like aluminum before the actual welding process begins.

The oxide layer on the surface of metals is formed due to exposure to air and can prevent proper fusion and bonding during welding. AC is used in TIG welding because it has the ability to alternate between positive and negative polarity, which helps to break up and remove the oxide layer.

The exact mechanism of AC's cleaning action is not fully understood, but it is believed that the alternating current creates a "scrubbing" effect on the surface of the metal, removing the oxide layer. This is because the positive polarity of the current attracts the negatively charged oxide ions, while the negative polarity repels them, causing them to break away from the surface.

As for where the oxide goes, it is not necessarily vaporized or dissolved. Instead, it is likely pushed away from the surface of the metal and collects in the form of slags or dross, which can be easily removed after the welding process is complete.

I hope this helps to answer your questions about how AC cleans the oxide layer in TIG welding. It is a crucial step in the welding process that ensures strong and durable joints. Keep exploring and learning about the fascinating world of welding!