Welding Stainless Steel - shielding gas question

[Asia]

I ran outta shielding gas for my mig welder. I've mainly been welding mild steel, but I plan on welding stainless steel in the near future. What percentage of shielding gas should I get? I currently have 75% argon, 25% co2. I was told to run 100% argon for stainless steel. Will it be a lot different welding mild steel with this percentage?

[parsonsj]

You want to use tri-mix for welding stainless with a MIG welder, and use SS wire as well. You'll need more heat than comparable mild steel settings too.

If you haven't MIG-welded SS before, you should practice a bit on scrap material. It's different, though not hard.

jp

[Asia]

what's tri-mix? another gas in addition to argon and co2? what percentage? Another forum noted that 100% argon helps welding temps for welding ss. Is this true? Thanks for the advice!

[toxicz28]

As JP said tri-mix. I believe it's argon/ co2/ helium. If you go into a decent welding supplier, and tell them you're mig welding stainless and need tri-mix, they'll set you up

[parsonsj]

what's tri-mix?Typical tri-mix is 90% helium, 8% argon, and 2% CO2.

jp

[Asia]

ok, cool. one more question. Can I run tri-mix with mild steel without problems? Thanks!

[parsonsj]

Can I run tri-mix with mild steel without problems? As opposed to the standard C02/Argon 75/25 mix? I've never done it. It will most certainly affect the weld, but I don't know how much. Plus, tri-mix is more expensive than the dual mix. I can't recommend it.

jp

[cm-67]

For MIG welding stainless steel, you may want to try A-1025 for your shielding gas. A-1025 is a tri-mix in that it contains three gases. But there are different blends of these gases, with the A-1025 being optimum. Results on mild steel won't be as good as 75/25.

Straight argon is used for TIG welding aluminum, stainless steel, and also mild steel.

You should also consider which grade of stainless steel you are welding and use the appropriate wire. If you will be welding dissimilar metals that will require a different wire also. Just because you are welding 304 base metal doesn't necessarily mean you use 304 wire, most people will elect to use 308.

Chris

[David Pozzi]

I welded steel with pure Argon once by mistake. The metal didn't flow out like normal and piled up. Not very pretty.
David

[Mathius]

I welded steel with pure Argon once by mistake. The metal didn't flow out like normal and piled up. Not very pretty.
David

You better check your setup again. I use straight 100% argon full time with my mig on mild steel. It's what we used in school too mostly. Easier than switching the tank everytime a student wanted to weld aluminum.

I've used it to weld stainless, but it didn't come out well, of course I was pushing my little 110 to the limits to weld 3/16" stainless, so that probably has a lot to do with it.

Mathius

[SBNova]

I used straight argon and it welded up fine, but I got alot of spatter.

[parsonsj]

I used straight argon and it welded up fine, but I got alot of spatter.That was my experience too. I haven't repeated the experiment.

jp

[Matt@RFR]

What David experienced was the result of changing gas without changing settings, more than likely. Straight gases, dual and tri-mixes will all run on mild steel fairly well, but will all require different voltage and wire speed settings. There is no argument here...just tuning required.

And CM-67; There's no such thing as an 'optimum' anything in this field when used in a global context such as you put it. The gas you mention (which is simply a trade name...why not state the percentages of each gas?) may work great for you, but garunteed somebody somewhere will be able to use a different blend with more success.

[kamaroman68]

Matt nice to see you back here!!!! Tried sending to your personal e-mail but it got kicked back saying unfound email address or something like that. Chris

[Matt@RFR]

Hey Chris, hit it again. I fixed 'er. I need to have Larry change my username too. One of these days.

[cm-67]

Matt, I disagree. There are gasses that will produce better results than others. I say A-1025 because it gives me the cleanest, best looking weld of all the gasses I have tried. Sure you can use other types but results will be different. When I use A-1025, it produces a flat (minimal buildup) weld with virtually no splatter. Whereas with other gasses the weld will not penetrate into the base metal as well and may splatter badly regardless of the settings.

A-1025 contains 90% helium, 7.5% argon and 2.5% co2

I can tell you that I have used it on 304, 310, 316, and also 321 stainless steels all producing the same results

As far as using it on other metals, I do not. I know that 75/25 is going to give me the best results with mild steel. At my shop we have a pulse mig that we use if we have to mig weld aluminum.

When I am tig welding I always use straight argon for ss, cs, and aluminum.

I always prefer to tig stainless and aluminum. Tig welding produces a much cleaner weld with more control, better penetration into the base metal and less cleanup. Mild steel I could go either way.

Chris

[Matt@RFR]

There are gasses that will produce better results than others.
I always prefer to tig stainless and aluminum. My opinion is that you speak way too generally. For example, you always prefer TIG on stainless? Always?? A few years ago I helped make 140 parts to make up San Francisco's new waist water purification plant. Those parts were big, all 316, took us atleast 4 months with 8 guys working on them and we went through about three pallets of 316L hard wire...much of the time laying on our backs on the floor welding the base frames and such. Would you have opted to TIG weld those?? Oh, and guess what gas we used. That's right, regular old tri-mix. We tried others, but the added cost of buying blends that are not as widely used was not worth any minute benifits they gave us.


Typical tri-mix is 90% helium, 8% argon, and 2% CO2.
A-1025 contains 90% helium, 7.5% argon and 2.5% co2 Yeah, I'm not buying what you're selling Chris. 1/2 a percent will not make a big enough difference for me to give two ****s about. Not when gun angle, weld prep, pre heat, individual operator settings, wire alloy and quality, base metal quality, gas flow, stickout, etc, etc will probably all have greater effects than a 1/2 percent difference in your gas blend. Either one of you has their numbers wrong, or we might also be seeing a locality effect. Just like buying 3003 H-14 aluminum sheet is as simple as asking for it at your local metal shop on the east coast, whereas on the west coast, you have to order it, and most shops have never even heard of it.

We'll just have to agree to disagree Chris. And in reality, when a guy comes to an automotive message board to ask what gas to use on stainless, my bet is he won't get any benifit for his task with an in depth discussion of gas blends and such. However, that takes an assumption that he's not welding anything important, so shame on all of you for not asking what "Asia" is going to be making. If he's making a stainless dash for his car, either tell him that 75/25 will work just fine if he's going to grind the welds, or simply tell him to tell his welding supplier that he needs to MIG weld stainless and to set him up with gas (as long as it's not pure argon! who the hell told you that?). BUT, if he's welding a tank for a local farmer which will hold some kind of acidic liquid, the situation changes drastically.

Talk amongst yourselves, I'll be back in a few months. :)

[cm-67]

Matt,
Either you misread my post or you have a very narrow knowledge of welding.
You acuse me of being too general, when in fact tri-mix is about a general a term as it gets.

#1 A-1025
#2 Stargon : argon, co2, oxygen
or argon, co2,, nitrogen
#3 Helistar : argon, co2, helium
#4 Robostar : argon, helium, and oxygen

All of these gasses are a tri-mix in that they have three gasses. However the blends and percentages are different and each will produce a different result.

You use the wrong shielding gas and you will be rewarded with a weld that is full of porosity, lacks penetration, and will be covered in spatter.I do agree that all of the other things you mention are important as well.

Chris