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View Full Version : Can I Weld Steel with 100% Argon Gas?



debequem
08-08-2003, 08:48 AM
Thinking about getting a small MIG welder and I would like to do aluminum, but some steel, too.

Will 100% argongas work for steel, or is it required to use a mix of CO2 and argon?

Marv

Arbo
08-08-2003, 10:08 AM
No, you can not use pure argon on steel. You need the CO2 mix commonly known as C25 or you can use pure CO2. The pure CO2 will improve penetration, but give more spatter.

wierdscience
08-08-2003, 11:07 AM
I have Tig welded steel with straight argon,but not mig,it seemed to me to over heat the nozzle and cup the few times I tried it,like said before tri-mix gas is best on mig forget the flux core as well.
I look at it this way,if I can't produce a perfectly clean weld with mig,than I may as well stick weld,lots cheaper for small jobs and a lot more flexible.We use tri-mix for steel at work and usually straigth argon for aluminum,with the tri-mix we get clean welds all the time.

Forrest Addy
08-08-2003, 01:36 PM
I use straight argon exclusively for TIG. I get great welds but I understand the mix is preferred.

ibewgypsie
08-08-2003, 01:52 PM
My little mig came with tri mix, argon, co2 and Oxygen, yes, oxygen. I discovered the non-ability to tig with this gas, the tungsten would evaporate upon striking the arc. It heats the weld up while welding thicker metals.


I have both gases now.

wmgeorge
08-08-2003, 09:17 PM
And so I have this tank of Argon and a roll of flux core wire... what happens when I use a light flow rate with the flux core? It seemed to have less splatter. B.G.

CCWKen
08-09-2003, 01:06 AM
Geez, I've never tried flux core with gas. I know one thing for sure--when you switch to gas, you need to switch polarity. (and vice-versa)

shorty
08-09-2003, 11:55 PM
flux cored wire runs with co2 just fine,

Thrud
08-10-2003, 05:58 PM
Marv

For non-critical applications pure CO2 is fine for steel. Ask your welding distributor for a copper coated wire alloy that works well with pure CO2 and you will be pleased with the results.

For critical welds in steel use helium (heli Arc welding) in a TIG torch for steel. Or use the proper rod and stick weld it.

Argon can be used for TIG of Aluminum and Stainless. Thoriated electrodes give the nicest Aluminum welds (it still takes mundo practice)

MIG Welding Aluminum must also use Argon, but the welds are not pretty - the welds must be spotlessly clean too!

Forrest Addy
08-10-2003, 06:29 PM
Pointing out the obvious, Weld prep cleanliness dept:

Aluminum rapidly develops a microscopic coat of oxide. High freq superimposed on AC was intended to combat this but quality welds are still obtained by mechanical wire brushing with a clean, never been used for any other purpose wire wheel immediately before the first pass and every pass thereafter. A 2" mounted shank stainless steel wire wheel in an electric drill works admirably for this.

MIG has practically zero fluxing action on steel. It will not break down mill scale. If you desire strong welds with good penetration you have to start with a clean, dry, bright metal weld prep.

Flux core wire is much better where weld cleanliness is a problem and duoshield (flux core and shielding gas) is even better.

Best of all for general purpose welding is stick with its strong fluxing and cleaning action.

I know guys who are constantly patching their heavy equipment by welding right over the paint and the grease. For some reason cylinder brackets and fittings keep breaking off right where they were welded. "Geeze, I welded that only a week ago."

One incorrigable garbage welder bunged up his back and his excavator broke down the same day. He asked me to patch up his machine so it would be ready by the next monday.

I took his helper and his breakdown truck off to the jobsite and together we went over that entire machine removing his dirty, porous, turkey **** weld repairs, cleaning them up and rewelding them with the right filler and a little pre-heat. Took us all week end.

Funny thing. No more structural breakdowns. Barney expressed bafflement to me a few months later. "I weld them up and they break and you weld them and they don't. I can't understand it." He couldn't either. He had it firmly implanted in his contractor's brain that welding heat "cleans" the metal.

Simple. I was trained by a welding expert, Ray Ludeman who taught me the importance of weld cleanliness.

When I re-welded the botched repairs on that excavator I started out clean and finised clean. Barney welded over the dirt.

[This message has been edited by Forrest Addy (edited 08-10-2003).]

Evan
08-10-2003, 08:33 PM
Forrest,

I have been properly insulted, apparently by an expert (former drip under pressure). My "turkey **** welds" break when they should on my snowplow. I hit a root a few days ago when making a fire break and shure nuff, the weld broke in just the right place. All in fun, you are, of course correct.

[This message has been edited by Evan (edited 08-10-2003).]

wierdscience
08-10-2003, 09:26 PM
Around here short wood haulers are the worst,half the wieght of the truck is useless weld and even more useless fish plates,but then again when I weld something for them they are amazed that it holds and pay me what I ask http://bbs.homeshopmachinist.net//biggrin.gif
The next worst are the aluminum flat boat owners who bring in their boats to be welded up only after they have tried everything from ductape to epoxy to patch the holes,they can't figure out why it takes me so long to clean the boat for repairs.

[This message has been edited by wierdscience (edited 08-10-2003).]

Forrest Addy
08-10-2003, 11:28 PM
Evan,

Yeah, I've done that: deliberately included a failure point intended to limit damage. Not on any weight handing equipment fer Pete's sake but other stuff subject to shock or unexpected loads - like a snow plow.

I usually use shear bolts though. I hate welding in 4 feet of muddy snow when I could just as well slip in a couple of spare bolts still warm from the glove box, back the thingy out of the ditch and wrench them up on the road.

Evan
08-11-2003, 12:12 AM
I can't count how many times the bolt that connects the snowplow blade to the angle drive has sheared off. I deliberately designed it to fail in the least important places. The blade is held on the front of my Land Rover with two bolts at the top, grade eight, at the bottom the bolts are grade three. If I hit something they will shear saving all sorts of damage. Design for failure is a very important and often overlooked feature.

shorty
08-11-2003, 12:19 AM
It should probably be mentioned that when grinding aluminum keep a special disk set aside so as not to contaminate the aluminum. Also use a stainless steel brush and ONLY use it for aluminum. Same reason. When using mig for welding aluminum run at a high voltage and if you decide to try arc welding it make sure you run on the high side ofthe rod specs for amps. A spool gun is your best bet for mig welding it because the aluminum wire is so soft it will inevitably "birds nest" on you. Be careful not to stay in the same place too long as the puddle will "fall" out on you leaving you a big hole to fill in. An aluminum "puddle" looks sorta like butter melting in a hot frying pan...just so you know what to look for.

alumtuna
08-11-2003, 02:55 AM
debequem,
U could use pure Argon but a mix with co2 about 25% will reduce spatter.
Pure argon could be used to weld al also. You could buy one bottle and exchange whichever you need at the gas supply/weld store.