gas for mig on ss

[sparky123]

i want to try to weld some stainless with my mm135. I have C25 gas and i was wondering if this would work or if i need pure argon or some thing else.

Nick

[hankj]

You need tri-mix. He+Ar+CO2. It's in your owners manual and on the door chart.

Hank

[aametalmaster]

It will weld just fine with 75/25 also. Bob

[DDA52]

I've been doing a project in ss with my MM 135. If you are doing a non critical weld, C-25 will work, just not well. Straight Argon didn't work well at all. It might if I could put more voltage to the work, but I doubt it. The beads were very cold looking and refused to do anything but pile up no matter what the voltage/ws. The C-25 beads were a little better, but they still piled up a bit and were blackened somewhat. I only need the ss to be sufficiently stuck together anyway.

[Teeps]

Is your material smaller than .080" ???

I think it depends on the thickness, but if your doing thin tubing like I am, and .025 wire, I've been told the Helium Tri-mix is not the best either, but don't listen to me, I'd rather someone who has experience welding tubing actually share their experiences.

I know I'm going to try two different gasses and post pictures of the welds, as soon as I get my 308LSi wire next week.

Having said that, I've heard c25 works, but makes a dirty weld. Helium tri-mix is what's recommended, and works good for medium to thick stainless. However, Tri-mix might be too hot for thin stuff like the 16 guage/ .062 tubing. I was told to use pure Argon from one guy, and the local supplier stated pure argon will not wet the puddle out well enough, and will leave a high weld bead (I take that to mean bad penetration) He said to use 15% C02 with Argon.

I asked him to make it 10%. I now have two bottles of gas, one bottle is 20% Co2 (was supposed to be 25%), the other is 10%, both with Argon. I'm hoping the 10% makes some nice welds, I will post results.
I would like to see what someone finds out with the Helium Tri-mix on tubing, as well as 2-4% C02 with Argon.

If I don't like either of the mixtures I have, I will probably try a tank of 2% C02 with argon next.

I'm trying to make some nice clean welds, of course I'm an amatuer so that my affect the results somewhat as well.

I posted up a link in a few other threads,

http://www.weldreality.com/stainlesswelddata.htm

[DDA52]

.

Having said that, I've heard c25 works, but makes a dirty weld. Helium tri-mix is what's recommended, and works good for medium to thick stainless. However, Tri-mix might be too hot for thin stuff like the 16 guage/ .062 tubing. I was told to use pure Argon from one guy, and the local supplier stated pure argon will not wet the puddle out well enough, and will leave a high weld bead (I take that to mean bad penetration) He said to use 15% C02 with Argon.

Teeps
FYI, my ss is 16ga. The c-25 is giving full penetration without burn-thru. The discoloration brushed off easily. The beads didn't wet well at all on AR, but did better on C-25. I have to grind the welds anyway so the piling up was an inconvenience only. If you can, post a pic when you get your gas mix. I'd be curious to see what they look like in comparison to mine.

[Teeps]

FYI, my ss is 16ga. The c-25 is giving full penetration without burn-thru. The discoloration brushed off easily.

Thanks for the info...

Yeah, it will be fun to see what differences, but I should also mention, in case it wasn't already a given. Having an Air-tight sealed weld is even more important than having a pretty weld.

Since mine is on an exhaust system.
I wonder if any of these welding gasses, or resultant by-products would result in pin-holes, or have any affect on that. Pin-holes = leaks, and back fires, ahhhh

I'm hopeing the extra silicone in my mig wire, and my stainless steel wire brush will help with that

Maybe I'm wrong, but I guessed the process for welding will basically go like this, cut the tubing to the right length, and angle, use a stainless steel brush to clean the metal near the weld joint, set it up under the car to the right fitment, tack it in 2 or 3 spots at each joint, once a section is done, Pull it out from under the car, and finish welding the gaps in the tubing, not sure if there are any caveats or rules of thumb on proper puddle/pattern and stroking, other than going slow enough for penetration, but not to hot for burn through.
Maybe some brushing off will be needed for dirty welds. Grinding is not needed right?
Maybe some sanding would reveal some pin holes and need for repair, dunno, I'm a newb at this.

I guess the pictures will speak a thousand words heh.

[hankj]

This horse has been beat severely in the past. Take a look here for another opinion. http://www.weldreality.com/default2.htm

Hank

[Teeps]

This horse has been beat severely in the past. Take a look here for another opinion. http://www.weldreality.com/default2.htm

Hank

Same site different page quoted below-------------------------
--------------------------------------------------

Gas Fact. Argon 3% CO2.
Range 2 - 4% CO2. (SG-AC-3)
Against the forces of aggressive gas salesmanship, fifteen years ago while working with AGA , I developed this gas mix for MIG stainless,

For the last 15 years I have been advising companies to use argon with 3% CO2. Instead of argon oxygen for stainless spray applications,
the argon 3 CO2 mix results in cleaner spray or pulsed welds with less weld porosity potential.

For the same period of time I have been advising people to forget the common, more costly 90 helium - 7.5 argon - 2.5 CO2 tri mix, and instead use the more effective argon 3% CO2 mix for those "thin gage" stainless short circuit applications.

In contrast to the costly helium tri mix recommended by all the major gas companies , there are six short circuit benefits attained from using the argon - 3 CO2 mix which provides lower weld energy with lower weld voltages; When used for "low carbon" stainless applications, the carbon content in the weld will be acceptable with this gas mix for both short circuit and spray applications.

In contrast to the more costly, higher energy, helium tri-mix, the argon - 3% CO2 mix when used on thin gage applications can provide;

[1] less part distortion,
[2] less weld burnthrough potential,
[3] less contact tip issues,
[4] improved arc stability,
[5] lower cost gas,
[6] more gas in the cylinders.

In today's North American weld industry in which gas marketing and gas sales strategy often has more in common with Disney Land than it has with MIG arc physics. It's been an uphill struggle to get the practical benefits of my two component CO2 message across. Try these mixes they works, are less costs and you get more gas from the cylinders.

[cope]

The big problem with Ed's recommendations is finding the gasses on the street.

[DDA52]

The big problem with Ed's recommendations is finding the gasses on the street.

Yup. That's the problem I had. Most would custom blend a cylinder for me if I wanted to wait for two to three weeks. That is one of the main reasons I used the C-25. This time it worked out.

[Teeps]

Yeah,

Shade tree guys that buy gas in smaller quantities are ok though, the place I go to the guy will custom mix the stuff in about 10 minutes, using the tank that I bring in!!! But he doesn't have the ability to do larger tanks this way (pressure levels). I'm sure most professionals would be using much larger tanks than I'm using... 40 cf, etc.

[DDA52]

You're fortunate. Noboby here that I've found can or will do that. It may be a little of both as it would require bending over. I even have the cylinder ( 80cf ), but no joy. I know that my old suppliers in Dallas and in Northern Va. could have set me up in no time. Things in the supply world are a bit sad here. If I decide later to get some, I guess I'll have to wait the 2-3 weeks.

[aametalmaster]

This is why I use 75/25 the number's may be off from the custom stuff but there is alway's a tank hanging on the back of my welder. Just switch the wire and we are off. I have a tank of Argon and I have used it but the puddle dosen't flow to suit me..Bob
Miller 185 w/ 185 Spoolgun
Miller Thunderbolt AC/DC

[sparx]

After reading all the posts/replies to this category, I just want to point out that using C-25 to weld stainless steel will result in the steel not being stainless anymore. The carbon content in the stainless stell will accept using 25% C02 for welding, but the additon of the carbon from the CO2 will result in a crack sensitive weld with a high afinity for rust.
just my 2 cents worth