Best gas mix for MIG welding stainless

StickPigBBQ

I have bit the bullet and decided to go with MIG instead of stick for my stainless project for the ease of use and need to finish the project for work quicker than expected. I have never MIG welded stainless before so I was wondering what I need to have gas wise to get the job done. Any other advice is appreciated as well.

Thanks,

Josh
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the420Angler · Newbie Joined: 10 Jul 2011 Posts: 77 Location: Barrie, ON

I run a mig/stainless setup and the local gas supply has a product that is a mix of CO2 and Argon I believe (I will check at work tomorrow). I am sure if you check with your local supplier that they will have a comperable product. Other than the gas, running stainless in the mig has no noticable diffence than from welding carbon steel and your tools will be the same.
In terms of grinding and sanding discs, dont mix steel and Stainless discs and use discs designated for stainless where possible. They are designed to work with the harder material.
Hope this helps. Let us know how you make out.
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bigmike782 · Joined: 12 Aug 2011 Posts: 19

If you use a sheilding gas with more than 5% carbon dioxide you will no longer have stainless.The weld pool will pick up carbon from the gas.
For short arc(most common MIG tranfer mode)I think you will find helium tri mix(sometimes called A-1025)is the gas that will give the best results.

StickPigBBQ · Posted: Wed Sep 28 11 2:13 am Post subject:

A local welding supplier recommended 100% Argon. It's tough to get and I haven't found anywhere locally for the tri mix. I can get 75/25 argon/co2 but it sounds as if that won't work well.
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TrailerBuilder · Posted: Wed Sep 28 11 2:22 am Post subject:

I have ran mig on a lot of stainless, my thoughts are that a tri mix is your best bet. 90% helium - 7.5% argon and 2.5% CO2. This is a common tri mix and I have had very little trouble with this shielding gas on stainless welding. I have ran straight argon before on stainless, but did not like the outcome of the weld, the only thing I use straight argon on now is aluminum. The worst part of stainless welding is the splatter that you get. The splatter basically welds itself to the stainless material and is a real pain in the back side to get cleaned up and looking good. I would highly suggest using an anti-splatter spray on your welds, it will save you a ton of aggrevation. Mig welding stainless, I run fairly high heat and a quick wire speed setting. Of course all this depends on your material thickness also. But I move along on stainless at a pretty good pace. With the higher heat and wire setting, I get nice penetration and a smooth bead, but go slow and you get a blow out that looks like hell and takes a bit to get repaired. I would suggest a piece or two of scrap and mess with your settings until you get what you like.

Hope this helps some

Just my 2c worth Very Happy

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Blazer · Posted: Wed Sep 28 11 3:14 am Post subject:

I agree with t builder they have special mixes for stainless. You will find each supplier has their own trade name and mixes. A lil nozzel dip will help your gun ,just run it on some scrap after dip it.

TrailerBuilder · Posted: Wed Sep 28 11 3:21 am Post subject:

Nozzle dip won't do you much good as far as the weld splatter on your material. Spraying an anti-splatter on the material your welding will help drastically in removing the weld splatter off the finished product.
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StickPigBBQ · Posted: Thu Sep 29 11 3:21 am Post subject:

Thanks for the info. I have called the local welding supply and it looks like the best I can do locally is 100% Argon. I can drive over an hour away for the tri-mix but if I want to deal locally its nothing but straight Argon. I suppose this is better than the Argon/CO2 mix? Im thinking of going with a Tractor supply 40 cu/ft bottle since they are 100 yards down the road and they offer the bottle exchange (kinda like the propane tanks at Wally world).
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cupped wings · Newbie Joined: 14 Aug 2011 Posts: 30

Ouch....100% argon on stainless is not a good choice in my opinion for a MIG shielding gas. I know that 75/25 is not the best choice either, but would prefer that over straight argon. It really depends on what you are welding and how critical the integrity of the weld needs to be. If this is just SS trailer fenders or the skin of a smoker it shouldnt be all tbhat critical. The problem with straight argon is that the puddle will be extremely sluggish and the weld bead will be ropey. What the 90% helium does in the trimix is get the SS weld bead to "wet" or lay down flat because of the icrease arc voltage the helium produces. Argon is basically a stabilizing gas and CO2 also adds heat to a MIG arc.

It would be worth the hour drive in my opinion.

Edit: I just realized you posted this on 9/28 and have probably already made your purchase.

How did the project work out?