Shielding Gas for Alloy 625

[dieselofdog]

I am going to run a PQR joining 625 (solution annealed) to itself using NiCrMo-3 filler. GTAW in the root and deposit 6mm of weld metal. Then GMAW-Pulse for the remainder. The test plates will be 40mm thick and double U Preps will be machined at 60 deg included.

What shielding gas is recommended for GMAW-Pulse process? I believe 100% Ar can be used but would a He blend be better for penetration and avoiding lack of fusion defects and toe wetting?

 

[metengr]

GMAW pulse should use 90% Ar- 7.5% He -2.5% CO2 or 75% He-25% Ar

 

[EdStainless]

I haven't seen people running a mix with CO2, but Ar-He blends are very common.
I have seen a lot of 75% Ar-25% He used.
He helps with heat transfer, but I don't think that will be an issue with your process.


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P.E. Metallurgy, Plymouth Tube

 

[weldstan]

Argon for TIG, Argon-He mixtures. We've used 60He-40Ar and the mixtures provided by metengr and Ed for GMAW.

 

[boo1]

we use 75% He-25% Ar