Pure Argon for ss

[fredo]

Can i use pure argon for mig welding 20GA SS sheet metal with HH175?
It is for a pasta plant where the pasta drys and it will get some steam.
What wire should i buy so i get the most corosion protection?

[fredo]

Please i need an answer for tomorow morning.

Thanks
Fred

[dee]

Originally posted by fredo
Please i need an answer for tomorow morning.

Thanks
Fred

Fred,
I Dunno- I dont do stainless- this link might help:
http://www.brazing.com/

Try the gas and the consumables section of this site or call the guy who runs the site (he's in Colorado I think)
http://www/weldreality.com

Is 100% Ar all you've got? He'll suggest something between a C2 and C4 mix

[fredo]

Dee,

Thanks for the links but pure Argon is the only gas that i can get here.

I will try with pure co2 tomorow for experiment also.

Fred

[Sberry]

Do you have any idea what the base metals are? That would help with choosing wire. CO2 isnt going to work. You might make it on C25 though.

[dee]

Originally posted by fredo
Dee,

Thanks for the links but pure Argon is the only gas that i can get here.

I will try with pure co2 tomorow for experiment also.

Fred

Fred,
If you are willing to suffer with the high amount of black discoloration from C25 go ahead, but at 100% Ar your weld will tend to be cold and will present a narrow fusion profile. You realize spray is the only practical transfer mode for that gas. Perhaps a larger diameter wire may help the low energy issue. Pure CO2 will not provide the result you said you need.

Why bang yourself in the head with these problems- try to get the right mix, it will be a better investment of your energy and time.

Check out the link I provided.; it goes to enough depth to save you some headache

[dee]

Originally posted by Sberry27
Do you have any idea what the base metals are? That would help with choosing wire. CO2 isnt going to work. You might make it on C25 though.

Sberry,
THose two links provide great breadth in filler metal selection. THe second site goes into great technical detail on filler as well as how the shield gas interacts with the rest of the GMAW process. Fredo has at his disposal all the information anyone could ever provide him with, and I'm going to go to bed and rest well knowing we've done all anyone can do short of running the beads for him.

Till next time...

[fredo]

Thank you Sberry and Dee

I,m going to try to know what base metal it is and for the proces from what i understand from brasing link flux core is my best bet.

Fred

[weld_slag]

I would not recommend 100% argon for MIG stainless. The bead will be narrow and ropey. C25 on 20 ga. will wok fine....certainly better than argon or 100% CO2.

[dee]

Originally posted by weld_slag
I would not recommend 100% argon for MIG stainless. The bead will be narrow and ropey. C25 on 20 ga. will wok fine....certainly better than argon or 100% CO2.

Slag,
As I said I don't do stainless, but I'm under the impresson C25 will leave a black deposit around the weld bead and HAZ. I understood part of the requirement was that the weld be free of that kind of discoloration. Not being proficent in Ni alloy characteristics I have no idea if it will effect corrosion resistance- I know it's a likely possibility and one of the primary concerns. C25 seems to disqualify itself for a variety reasons... any comments relating to those?

What do you mean by a "ropey" bead? Are you using parameters closer to those recommended for Al or to standard short-arc welding of steel?

I think the problem is how to get technique and process control to overcome the limited options...
...Flux core!
(smoke-em-if-ya-got-em)

[Roger]

A lot of Stainless Steel welds in food plant must not have any cracks or rust that will hide bacteria. For counters, weld then grind welds flush and smooth. Welds should be pasifated to remove surface iron preventing later rusting. Welding shops sell real nasty acid mixture for pasivating which includes hydrofloric acid. Absolutly no skin contact with hydrofloric acid products. Better to use electro polish with milder acid products.
Use Google GroupSearch to search newsgroup sci.engr.joining.welding for information on pasivating stainless steel.

[weld_slag]

Originally posted by dee
Slag,
As I said I don't do stainless, but I'm under the impresson C25 will leave a black deposit around the weld bead and HAZ. I understood part of the requirement was that the weld be free of that kind of discoloration.

I have welded stainless plenty of times with 75/25 and have never experienced the black deposit that you speak of. I re-read the original post:

Can i use pure argon for mig welding 20GA SS sheet metal with HH175? It is for a pasta plant where the pasta drys and it will get some steam.
What wire should i buy so i get the most corosion protection

I don't see where there is any discoloration free requirement in it.

Now granted I would not say that 75/25 is the best, but it will do in a pinch. I have fund that on light gauge sheet metal excessive spatter is no problem with C25. Normally I would recommend a helium/argon/co2 blend.

[dee]

Originally posted by weld_slag
I have welded stainless plenty of times with 75/25 and have never experienced the black deposit that you speak of. I re-read the original post:

I don't see where there is any discoloration free requirement in it.

Now granted I would not say that 75/25 is the best, but it will do in a pinch. I have fund that on light gauge sheet metal excessive spatter is no problem with C25. Normally I would recommend a helium/argon/co2 blend.

Slag,
Sorry about the misinterpretation.

I apparently stand corrected.

At the risk of re-repeating myself, I never have worked stainless. (except to braze) I do recall reading something somewhere about some carbon issue though. Can't say it's understood at this point.

What's the deal with the three part gas mix? The guru I use makes a strong argument against it. When I follow his advice it always works as he described, but I get a lot of strange looks at the supply shop and wind up buying a custom mix.

Sorry if I'm starting to sound like a little kid with his "why" button stuck. I've no immediate need for the information; no project in the works. I just like being enriched and enjoy this discussion.

[Carl T.]

Everything I have read recommends using 98% argon and 2% oxygen. The oxygen burns up any excess carbon and leaves a colorless weld. Second choice is 100% argon, according to most gas suppliers.

[fredo]

Again, thank you for all the info.

Carl T you say 2nd choice is 100% Ar, is that with solid or flux core wire?

The only gas i can get in Haiti is 100% Ar or 100% co2, any other gas i would have to order from Miami. Verry expensive!!

What about stick??? I don't care about color, i just don't want rust.