American Welding Society Forum
WE use 75% Argon 25% CO2 and I was told this mixture would provide better penetration than 95% argon 5% CO2. is this true? GMAW,.045,Spray transfer. Majority of the welding is flat fillet. I was always under the impression that shielding gas was primarly a protective enviroment for the weld pool and that it did not effect the current.
It might be a good idea to talk to the sales rep or technical department of the company you buy your gas from.
Even better yet, what process are you using? Gases behave differently with different processes.
Give us some more info about your operations and set up and maybe your question could be answered better.
Here is some good information at Ed Craigs site
Have a good day
Gas mixtures have a pronounced eefect with GMAW. You asked originally about penetration, I think the mix you mentioned 75/25 would provide more penetration than the 95/5. However, other properties change such as impact, tensile, etc. with changes in shielding properties. The penetration profile itself may be of concern (or in our situation more of a concern) in addition to the depth of penetration.
Another post regarding shielding for GMAW recently mentions many of the variations that occur with shielding variations.
As stated in another post, the shielding gas for GMAW is very critical. Not only does it "shield", but it can have an effect on the penetration, metal transfer mode and chemical composition of the weld. (Probably forgot some other influences.)
You state that you are welding spray transfer. Under normal circumstances, you would not weld spray transfer with a shielding gas with more CO2 than about 18%. (If I remember correctly.) This means that going to the 75/25 mix will significantly affect your whole welding set-up.
It is so that in general the addition of CO2 increases the "heat" of the welding arc, but above around 18%, it inhibits spray transfer which then again starts to decrease the penetration effects.
You need to match your gas to your job. If you are welding thinner members, then a lower % CO2 is better. When welding thicker members, then a higher % CO2 is better. If you want to weld spray transfer, you must have less than 20% CO2. If you want to weld dip transfer, then the 25% CO2 is a good gas.
Hope this helps
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