Plasma Shielding Gas

[birur_can]

Hello,
I have been told that 5% H2-Balance Ar is a good shielding gas for plasma welding. Any idea why this is the case.
Also can I use this for welding any material.
Thanks

[DrIQ]

The 5% H2 95% AR is used for the shielding gas and Argon for the plasma gas welding 300 series stainless or the other nickel alloys. The H2 breakes up the surface oxides and allows the weld puddle to flow better while reducing the heat-affected zone.

The same gas mix works well with GTAW on the same alloys, it reduces the width of the weld and increases the depth of penetration. One word of caution do not use the 5% mix if the part is to be formed after welding. Because of the narrow heat zone most of the material yield (movement) during forming would be in the weld and can lead to cracking. In most of the applications that involve forming after welding I would recommend 25% HE which widens the weld zone and somewhat aneals the heat-affected zone.

Do not use the H2 mix with steel it could cause hydrogen embrittlement.

[Hotfoot]

Now I know why they call you Dr. IQ!!:p