MIG welding stainless exhaust

[faero]

First post! I've read a fair bit on this here but posting on my specific requirement to see what the consensus is.

So foolishly decided to make up my own stainless downpipe for my car project and have probably spent more now on bits that just getting someone to make it... but that's not the point! TIGing would be the best I suspect....

So I have:
Clarke 135TE mig with Argon CO2
Autodarkening mask
3" diameter stainless exhaust parts. Not sure diameter but maybe 1.5mm tops?? Need to check. 99% sure it's 304 stainless.

I want to make the best welds I can for the kit I have so:

1) What type of wire? Thinking 0.6mm Stainless wire. Or will 0.8mm be better?
2) What grade of wire? Dont see any 304 for sale? But see 308 and 316.
2) Should I grab a can of pure Argon to improve the finish?
3) I read stainless will spatter more. Does anti spatter spray actually 'work'?

Advice appreciated!

 

[Justme]

Only one I can answer is about the anti spatter spray. Its not to stop the spattering ahppening but to stop it sticking to the work. Yes it works. Also get some "tip dip" that works too.

Justme

 

[Omniata]

You'll probably be better with pure Argon too or a disposable bottle if your not doing a lot of stainless.
Stops the introduction of carbon into the weld to prevent contamination...

Jim.

 

[faero]

thanks - I'll get some anti spatter spray to help clean up and a small can of Argon too.
I think I might end up going with 0.8mm stainless wire as there's much more choice now I look - as I only need a little, machinemarts £15 pack will do me fine.

I cross checked the 'estimated metal thickness' guide here and it seems 0.8mm wire might still be ok. (i.e. not too large)

 

[BRIAN SAUNDERS]

Stainless Without Pain

First post! I've read a fair bit on this here but posting on my specific requirement to see what the consensus is.

So foolishly decided to make up my own stainless downpipe for my car project and have probably spent more now on bits that just getting someone to make it... but that's not the point! TIGing would be the best I suspect....

So I have:
Clarke 135TE mig with Argon CO2
Autodarkening mask
3" diameter stainless exhaust parts. Not sure diameter but maybe 1.5mm tops?? Need to check. 99% sure it's 304 stainless.

I want to make the best welds I can for the kit I have so:

1) What type of wire? Thinking 0.6mm Stainless wire. Or will 0.8mm be better?
2) What grade of wire? Dont see any 304 for sale? But see 308 and 316.
2) Should I grab a can of pure Argon to improve the finish?
3) I read stainless will spatter more. Does anti spatter spray actually 'work'?

Advice appreciated!

1. 0.8mm

2. 308L

3. Pure Argon, or Argon/Hydrogen

4. Anti-spatter does work, but get a good make and don't over do the spraying.

5. If all else fails, find a freindly fabricator.

 

[malcolm]

I have a shiny stainless exhaust sitting just behind me at the moment. Copped out and bought it from the shop.

I reckon your exhaust will be 304. It's the most common type of stainless used in exhausts. Have made manifolds in the past though using 308 wire 0.8mm thick (only because it was easilly available from Halfords in handy 0.7kg rolls. I'm led to believe it wasn't a bad choice but not perfect. Search TechnicAl's posts for a more correct view). 0.8 is probably easier than 0.6 on 1.5mm wall thickness. Bead will be wider and flatter.

For the gas I used BOC argoshield light which isn't strictly correct. The BOC stainshield is much the same less the 3% CO2. Fine for exhausts but leaves a little soot around the weld. I've tried pure argon on stainless too. Gives pointy welds and roughness due to stray arcing, but otherwise fine. If disposables were the only option I'd go pure argon. If you have a bottle of argoshield light I'd prefer to use that.

I think I used anti spatter spray last time I welded stainless. It is helpful stuff. Otherwise file the spatter off afterwards.

These are the ones I made somewhere around 2002.

 

[Hitch]

0.8 wire will be fine.
Grade, get the 308L
Gas, if your on disposables, proably best off with Argon. Not sure what mix they put in the co2/ar mix ones.

Yes, stainless does spatter more, if theres a lot of welds in a small place, like a manifold, antispatter looses its effectiveness beceause of the heat.


Make sure you use plenty of tacks, stainless can ahave a habbit of opening up if you dont put enough tacks on.

 

[faero]

Thanks folks!! much appreciated and all noted. Will report back once I've blown a hole through the most expensive bit of pipe.

 

[faero]

ok - so I first had a play with Mild steel and CO2 on my little Clarke 135TE. Control isnt too bad and I can get some really nice welds after some practice with good penteration.


Last night the stainless wire arrive along with a bottle of pure Argon. (it was either that or 80/20 Argon/CO2) I have no other options in budget.

To get this to work on 1.3mm walled stainless tube - I had to drop the power setting right down (minimum and '1' on the panel) and almost double the wire speed to about 4.5 to 5.
Everything was much hotter and more frantic. Dropping the wire speed to anything less meant that a 'globule' formed on the end of the wire which then dropped into the weld and repeated. Increasing speed got rid of this but it was still not exactly relaxing with plenty of variation on how the weld was moving along...
In the end I got some nice welds and with practice they will be just the job - It showed up the controls of the Clarke 135TE as limited though as setting 1 was a little too low (narrowish welds) and setting 2 way too much. Annoying but I'm on a budget.

Anyway - Should I have expected such a difference in settings between mild and stainless of similar thickness and same dia wire - 0.8mm?

 

[matt1978]

Sorry to be the bearer of bad news but..........

The main 'big' differences you are experiencing is because 100% Ar is not the gas to be used on Stainless steel mig, you would of been better off with a 95%Ar 5% Co2 mix (Argoshield light or simerla). You could of used this on your Steel and your Stainless..........although 5% Co2 is technically not the right gas for Stainless, (its actually 2-2.5% Co2 in Argon or a Tri mix Ar/He/Co2), but nonetheless you would of got much better results with the Argoshield light than using 100% Ar and you could of done away with your 100% Co2 bottle.

Thats assuming of course, that Argoshield light (5%) mix is available in disposables??

If not and your only choice would be 100% Ar or 80/20 mix, I don't know which would of given the best results as neither gas is ideal, the 80/20 would of given a smoother flatter weld, but would most probably of rusted in later years, so you prob made the best of a bad situation

 

[faero]

This was indeed my issue. I am not doing nearly enough to warrant anything but disposables and as I am using this on an exhaust in quite a stressed area I ditched the idea of the 20% CO2 80% Argon disposable in favour for the 100% Argon disposble.

I did a fair bit of searching but no disposable Argoshield Light or similar to be found

TO be fair, the welds are OK for this. It's just the method is a bit intensive!

 

[rusty69bus]

just been doing a small bit of stainless welding fuel filler pipe with

308 wire 0.8mm thick (only because it was easilly available from Halfords in handy 0.7kg rolls

- thanks malcolm ) with a bottle of tcx. came out quite nice.

 

[faero]

What is 'tcx' ? Searched the site but no results on it.

Cheers!

 

[rusty69bus]

argoshield universal x being size of bottle