Backing Shielding Gas Medium

An inert gas or gas mixture introduced to prevent oxidation and root discoloration on the root side of the weld during the joining process. It protects reactive molten pool components from atmospheric contamination.

Backing gas is basically an inert gas, usually argon, that you apply to the hot root side of the weld. It prevents oxygen from the air from reaching the metal and oxidizing it. If you skip it, you'll get scale and discoloration on the back, and the weld will become brittle and not hold properly. You have to direct the gas so that it covers the entire root cleanly. If you don't control the flow, you'll pull in air rather than protect. Make sure the gas flow stays constant during welding, then it'll be fine.

MetallurgieSchweißtechnik