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View Full Version : Can you mig steel with 100% argon?



12,000 Doors
01-23-2007, 08:47 PM
I've heard yes and I've heard no, it doesn't "sit right". According to my old boss you can subtitute argon for steel but not argon/co2 for aluminum. Argon for steel seemed to work all right when I did it but how does the weld measure up strength wise I wonder. If anybody's got the answer for this question out there I'd sure like to know. The guy who said you can't was selling the mix for more and I wonder if that had anything to do with it.

MicroZone
01-23-2007, 09:02 PM
It is preferred to use a 75/25 mix. I believe my current bottle connected to my TIG is 100% argon.

Clanweld
01-23-2007, 09:38 PM
You can use 100 percent argon, but you will not be satisfied with the bead you get when welding mild steel. Because Argon has a low thermal conductivity, you will end up with a finger-like penetration into the base metal as opposed to the broader even penetration of a 75/25 mix.

zapster
01-23-2007, 09:48 PM
The 75-25 that everyone is telling you about is 75% argon 25% helium..
Thats the "mix" for A.C. aluminum..
Straight argon for tig welding steel..stainless...and a viariety of tool steels..

Straight helium can be used for aluminum..D.C.straight......but its dirty and messy..and usually used for big thick stuff..

But yes argon is good mig gas..

...zap!

Doolittle
01-23-2007, 10:10 PM
Ive been hearing good things about c10, what do you guys think?

littlefuzz
01-24-2007, 12:18 AM
Argon gives a higher profile bead on mig. Doesn't look as good. It'll work if ya have to have it right then but I don't like it.

MoonRise
01-24-2007, 01:07 AM
Zaparoni,

The 75-25 in question here for MIG and mild steel is 75% Argon and 25% CO2.

A mix of argon-CO2 is usually used for mild steel GMAW. Pure argon works, but may not be the 'best' choice for GMAW and mild steel. I currently have a tech question in to the folks at Lincoln about that very question, or one pretty closely related (actually it was regarding the apparent increasing Charpy V-notch properties at lower temperature as the argon percentage increased compared to the CO2 percentage).

C-10, C-12, C-15 are good all-process gas mixes for GMAW and mild steel. They will support short-circuit, globular, and spray transfer modes if the machine can get the right voltage and amperage outputs.

jamlit
01-24-2007, 05:33 AM
I did allot of research on this. My findings were that pure argon can be used on mild steel but the weld penetration will be deep but very narrow. It is not recommended but can be used as a last resort. C25 ( 75% CO2 25% Argon ) and straiaght CO2 are both used on mild steel for general and certifed welding. Straight argon can be used on a mig for stainless and aluminum and Their maybe other argon mixes that may work better but I am not fimilar with them.

The one thing I am finding about gases is that their seems to be allot of different types and opinions on them. Some gases your dealer may not even have heard of yet as I found out the hard way. I use CO2 and C25 on my mig and Pure Argon for my tig.

lotechman
01-24-2007, 08:13 AM
If one looks at the specs on wire there often is a caution that increased argon content will raise the yield strength and ultimate strength. This is not a good thing if one is looking for ductility in the weld. The weld metal strength and other physical properties will be given for straight carbon dioxide with the associated caution.
Pure argon is not practical for welding steel. Certainly you can run a bead but it is not a thing to do from an economic/commercial view.

littlefuzz
01-24-2007, 09:09 AM
I thought it was 75% Ar and 25% CO2? I believe jamlit has it backwards.

MicroZone
01-24-2007, 12:46 PM
Yes, it's 74 Ar / 25 Co2.

pulser
01-24-2007, 02:05 PM
Lotechman makes an interesting point.

"If one looks at the specs on wire there often is a caution that increased argon content will raise the yield strength and ultimate strength. This is not a good thing if one is looking for ductility in the weld. The weld metal strength and other physical properties will be given for straight carbon dioxide with the associated caution."

In GMAW and FCAW, some of the elements in the wire electrode are volatilized and lost in the arc, depending on the percentages of reactive gases CO2 and O2, and therefore the weld metal chemistry and resultant mechanical properties such as tensile strength and ductility can be affected.

I heard a presentation concerning the improper use of self shielded FCAW wire with an added shielding gas. Apparently the welder decided that the weld ran better this way, maybe less spatter, better puddle control, whatever. There was a problem with this, and I don’t recall if the weld failed in use, or in qualification testing, but it was found that the weld was actually too strong, and lacked the necessary ductility for the specified notch toughness specification. Because an Argon rich shielding gas had been used, the normal element loss that was accounted for in the design of the self shielded wire did not occur, thereby making the weld metal too rich in certain elements, raising strength and lowering ductility outside of the intended design range.

I am not aware that gas shielded FCAW wires actually specify the type of gas to be used, but it makes sense that they may, just never worked with these. As far as solid wire for GMAW, I have not seen certain wire types such as E70S-2, -3, or -6, specifying use with a certain gas, although it makes sense that weld properties would be different for a 100 % CO2 weld versus a 92 % Argon/8 % CO2 weld.

12,000 Doors
01-24-2007, 08:04 PM
Narrower penitration, reduced ductility, sounds pretty serious. It's always been tempting to just dig into the aluminum welding gas when the steel welding gas runs out. I'll definatly think twice now. I hope others learn this lesson too because it sounds kind of like an accident waiting to happen. Thank you all.

littlefuzz
01-24-2007, 08:11 PM
Here at work we use 95% Ar 5% O. It welds pretty good. We use the B.F.T.'s

lotechman
01-24-2007, 10:34 PM
If anyone is curious you can go to the Lincoln website and download their product catalogue for MIG wires. The detailed summary for each wire gives the ultimate strength, yield strength and Charpy impact strength when using different gas combinations. For the average person this is not a big consideration. If, however you are building large steel structures this is a concern. The Charpy impact value is very important if your weldment is going to be subject to severe winter cold and vibrations or sudden loads.
http://content.lincolnelectric.com/pdfs/products/literature/c410.pdf

pulser
01-25-2007, 10:31 AM
Lotechman,
Thanks for the Lincoln reference.

smithboy
01-25-2007, 01:42 PM
I have migged steel with 100% argon (all agricultural implements). I never have had a problem. The only issues I have had is with burn-through on thinner stuff...I guess it's related to the penetration mentioned earlier. My understanding is that brittleness is the biggest issue, but that hasn't adversly affected stuff I have welded so far. The beads do look different...taller, narrower.

One question I have always had is why pure argon affects mig-welded mild steel differently than tig-welded mild steel? Is the additives in the tig filler that different?

ramblerx15
01-25-2007, 02:18 PM
Years ago, I worked at a bicycle factory, and they used 100% argon. Spray transfer and fast travel robots really moved things along. The reason that I heard was very little spatter, and it worked, as there was only a dynafile used for cleaning spatter off of maybe 1 out of a hundred frames. I can't recall the amps used, but it was .035 wire fed out of drums on 18 gage tubing.

J M B
02-13-2007, 05:39 PM
Yeah, today I ran out of gas on the mig and borrowed 100% argon from the tig. Very little to no spatter with the increased chance of undercut, and it was almost like it was spraying. I did not like it.

Joe5688
02-13-2007, 05:52 PM
So i assume, tha the mix that u guys use is 2 tanks. The regulator just controls which goes to each?

Or is it that both are in the same tank. Is that possible?

Doolittle
02-13-2007, 09:36 PM
Yep, its the same bottle, they mix it at the gas place. Pure Argon is on the tig welders. BTW, thanks for the lincoln link.

David R
02-13-2007, 10:26 PM
If you run out of 75/25, I think you would be better off going for a bottle of Co2.

David

gkent
02-13-2007, 10:38 PM
I just switched to 75/25 and couldn't be happier. The welder runs in "spray" mode, the welds look great and there is virtually no spatter - hence very little time wasted on cleanup. The penetrationis better than 90/10 or 100 also.

o.c.d.
02-13-2007, 10:44 PM
Hi Zap,

I don't mean to jack the thread, but being new to TIG and reading many of your posts. You said that 100% Argon is not correct for TIG welding aluminum? I should use a 75/25 mix, or If I recall correctly according to one of your posts you mentioned using a custom 70/30 or 85/15 Argon/Helium mix? How do you mix this way from 2 cylinders? Set one flow rate on one and the other for a percentage to equal the whole?

gnm109
02-14-2007, 03:58 PM
Hi Zap,

I don't mean to jack the thread, but being new to TIG and reading many of your posts. You said that 100% Argon is not correct for TIG welding aluminum? I should use a 75/25 mix, or If I recall correctly according to one of your posts you mentioned using a custom 70/30 or 85/15 Argon/Helium mix? How do you mix this way from 2 cylinders? Set one flow rate on one and the other for a percentage to equal the whole?


Zap mentioned 75/25 Argon Helium for TIG. Tha twould certainly work. I use pure argon. I guess you could add some helium to gain greater heat for larger work.

The typical 75/25 mix for MIG is 75 argon/25 CO2 as far as I know.

The easiest way to get a mixed gas is to order a cylinder that's already mixed. Some people do it with two cylinders and a manifold but that's out of my league.

smithboy
02-17-2007, 01:23 PM
Don't use anything with CO2 in it for tig...The mixes for Tigging are all inert mixes. CO2 is not inert. It's definately "ert."