Welding stainless steel with MIG

[Zombie]

Firstly, my knowledge of welding is very limited. I'm hoping to expand my skill level from bird poo to something a little better. Thought I'd try to achieve this by making a couple of exhaust projects.

The first should be fairly easy - a couple of bent bits of pipe with hangers to replace the rear boxes on my 159. The second job, is more ambitious. I want to take some old tubular exhaust manifolds and replace the outlet flange type and position. Which will require a jig, at the very least.

But to begin with, what do I need to start welding stainless?

I have a half decent mig welder with Argon 5 gas.

Looking online it appears that Argon 5 is 93% Argon, 5% Carbon Dioxide and 2% Oxygen.

A youtube tutorial for welding stainless suggests 90% Argon 7.5% Helium and 2.5% Oxygen is what I should be looking for but getting a refill of the Agron 5 proved to be right faff last time around which I want to avoid.

Will Argon 5 work?

What else do I need in terms of materials? Stainless wire?

Thanks in advance!

Edited by Zombie on Sunday 17th February 23:00

[bearman68]

You're clearly going to need the correct grade of stainless wire. That's gonna be expensive. Bear in mind exhaust stuff is generally very thin - what about 0,7mm or so, so the wire you need is going to be less than that (0.6mm?) - that's getting close to the limit of most MIG machines that I'm aware of. It's unlikely you will be able to weld a continuous bead at that thickness.

If you have a genuine long term ambition to weld stainless, there's only 1 way to do it, and that's with TIG. It's very dull welding with TIG, as it's really, really slow, but it does a fabulously neat job. You can also swap filler rods for different grades of stainless very quickly, easily and cheaply. This is where I would be spending my time and effort.

My local tech has been offering welding training (Grade 2 or 3 NVQ TIG) for £500 for about 90 hours of tutored welding - if you can manage an evening a week, it's a great way to learn. I've been busy on this for a while, and I've learnt loads.

This is my experience and comments anyway - others may have more or different experience.

[GreenV8S]

bearman68 said:

My local tech has been offering welding training (Grade 2 or 3 NVQ TIG) for £500 for about 90 hours of tutored welding

Are you sure you didn't miss a zero off there? That sounds like an excellent deal!

[dhutch]

Zombie said:

Firstly, my knowledge of welding is very limited. I'm hoping to expand my skill level from bird poo to something a little better. Thought I'd try to achieve this by making a couple of exhaust projects.

Personally I would spend some time practising your welding skills before taking on this project.

Thin material is a lot harder to weld than thicker material.
Tubes are harder to weld than straight welds
Stainless is (I believe) harder than mild steel.
Manifolds or anything where access is limited is harder.

I would get some scrap steel around 3-4mm thick, depending on the welder you have and the wire you have with it and start running some welds on it. Working till you get a good looking weld, tested for strength, etc. There are some reasonable guides here: https://www.mig-welding.co.uk/tutorial.htm

Then once that is going well, and you have the machine set-up, and producing good looking welds with suitable penetration, no big holes, etc. Then you can drop down the thickness 2mm, 1.5, 1mm till you get the hang of that, short stitches

If you wanted to you could do all of the above in stainless, but I wouldnt. Less people do it, there are less guides on it, and the materials cost more.
Unless you feel your calling in lift is to make exhausts, in which case as said, you want to be learning TIG welding, which is fairly different in terms of process, equipment, materials.

I did a 10 week (2 hour per week) oxy-acetylene welding course at the local collage, day release from school in something like year ten and loved it, from there I self-taught myself mig in the schools project shop with mild supervision, did a bit more a uni with the motorclubs gear, and then bought my own which I use on bits for the car/boat/life if only just enough to justify it.

If you can get a local evening coarse for sensible money that is well worth it in terms of not just the tuition but also the provision of the kit and materials. You may even be able to take you exhausts along to make in the latter lessons.


Daniel

[hidetheelephants]

Argon 5 isn't ideal for welding stainless but for DIY you won't notice any practical difference, especially on an exhaust that will be out of sight. Buy yourself a reel of 308 wire and have a go with some scrap to get a feel for it, then get fired into it; watching yootoob vids, reading manuals or being told what to do only gets you so far, doing is learning. A stainless steel wire brush is advisable as using an ordinary one for cleaning up will promote rust staining.

[Pjhuk33]

Mig welding stainless leaves a very unsightly weld.. If it's going to be on show Tig it...
Mig has its uses as it's fast and relatively easy.
Tig takes time and skill...
As far as gases go if it's got to a clean weld as BOC which gas they recommend....
My experience mig leaves a very agricultural weld. Pulse mig with the right settings is better ie if you have a washroom floor to weld together but fk me what a faff.
Just my experience

[Zombie]

Thank you for all the responses, everyone. Much appreciated.

[bearman68]

GreenV8S said:

bearman68 said:

My local tech has been offering welding training (Grade 2 or 3 NVQ TIG) for £500 for about 90 hours of tutored welding

Are you sure you didn't miss a zero off there? That sounds like an excellent deal!

I'd struggle to cope with 900 hours welding. I think it works out at about £512 for 30 weeks of 6pm - 9pm with some great quality kit, an assortment of welders, and an almost unlimited supply of various thickness mild steel, stainless, or ally. It's a really fantastic course, and the tutors are knowledgeable and good teachers too. It really is hard to fault.

Well, if I had a criticism, the tech has sub contracted the cafe, and despite perhaps 100 night school students, there's nowhere to get a cup of tea. (OK, it's not the biggest problem in the world).

[dhutch]

bearman68 said:

I'd struggle to cope with 900 hours welding. I think it works out at about £512 for 30 weeks of 6pm - 9pm with some great quality kit, an assortment of welders, and an almost unlimited supply of various thickness mild steel, stainless, or ally. It's a really fantastic course, and the tutors are knowledgeable and good teachers too. It really is hard to fault.

Sounds good to me!

Nothing beats having someone knowledge there showing you what you're missing, much better to use youtube in conjunction with that than alone I'm sure.

Daniel

[PaulKemp]

I did a short course at a local agricultural college, great fun, to short but gave me a practical knowledge of mig, arc & gas.
Gas is hard, one guy did 10 weeks on gas alone.
Ultimately it’s just practice, practice, practice and an awfull lot of scrap metal.

[MatrixXXx]

It is posible to weld stainless with steel wire and co2, but to do it properly you want stainless steel wire and argon, and idealy on a bench, welding on the vehicle can be exstremly difficult.