Mig welding stainless

[AndrewH]

Advice please!!

I'm welding 2 mm stainless, fillet welds, 0.8 wire. with argon as the shielding gas.

Should I be using a different gas?

 

[^neo^]

Pure argon?

 

[matt1978]

Technically you should only use around 2% Co2 in Argon, or a Ar/He/Co2 mix.

But, that said it depends on the application of what it is your welding........

 

[dannyweld]

get some argo sheild light, good general purpose choice

 

[malcolm]

What problem are you having? If your welds aren't flowing very well and are turning out a bit tall and pointy, or are generally just a pain in the rear, then something like Argoshield Light should make things easier for general purpose Stainless use.

Does depend what you are doing as has been said. I use Argoshield Light on stainless for car exhausts myself as pure argon can be a bit of a pain. I'd imagine the food industry would stab me with their knives if I tried that with them, and the potential for being run over by heavy machinery rules that out that line of work totally for me. For anything really proper there are stainless gas mixes.

Might be worth posting a photo or two of the welds and describing the problem you want to sort as well as the application.

 

[breezer]

I know people who swear by using normal mig wire when welding stainless, suppose it depends on the end application as to whether that's any good for you

 

[malcolm]

Normal mild steel MIG wire does make stainless welding easier, but it more than defeats the point of using stainless in the first place. Mild steel wire welded structures last longer and perform better when they are made from mild steel. Even on mild steel to stainless joints it's best to use stainless wire.

 

[dannyweld]

reminds me,my father got some guy in last year for a few days and he welded up some stainless with mild steel wire, a total disaster, i had to cut and grind all the weld away and then weld it up again and make it look like new. anyway, i use 316 wire even though i mainly weld 304 as i find the 316 wire is harder and is easyer to use (i think). i have used pure argon to MIG weld stainless before but its more difficult and the result is poorer, it was a saturday morning have just ran out of gas kind of thing.

 

[malcolm]

From memory 316 is the stuff to use for 304 stainless. Fairly sure that's what I decided was best, but somebody has had my wire so I can't check for certain. A search on the forum might confirm. Welding messes up the material a little so don't be surprised if a different grade of wire is recommended for the material.

 

[Hitch]

308 for welding 304
316 for 316
309 for s/s to mild
They are probably the three most common ones.

 

[chunkolini]

So what gas then?
I was welding 304/308 stainless, the basic grade; a lot, getting tidy welds, but lots of spatter. I was using argon/CO2/O2 mix, cant remember the proportions. I had a go with pure argon, a hideous mess if I remember rightly the metal was flowing and melting all over the place..

So is there a specialised gas mix for SS?

Chunko'.

 

[AndrewH]

Thanks for all the responses.

BOC Pureshield argon is what I'm using.

The component being welded is part of a boiler, its like a box with with about 25 7/8" tubes going through, the tubes are tig welded into the box each end. The box (2mm material) is then mig welded - just had a look at BOC's web site, perhaps Ive just got to bite the bullet and get another bottle of gas!! "Stainshield light"??

What do you guys suggest?

 

[Welderpaul]

So is there a specialised gas mix for SS?

Chunko'.

Yup - Stainshield: http://www.bocindustrial.co.uk/boci...ion/gas/shielding_gases/stainshield/index.asp

And Stainshield Light is what you would use in an ideal world

 

[dannyweld]

mainly use 0.8 316 wire in the mig for the 304 1-3mm. have been also welding 5-6mm box and plate with this role of wire and am not so happy then with the results. was thinking of getting a role of 1.0 for this heavyer stuff. maybe wound try a role of 308. like the 316 as its hard and suits pulsing. the wire sometimes fails to arc properly and bounces of the metal, with quite some force. am using 1.2mm wire to weld mild steel 2-3mm with inverter mig and am well happy with the results. the price of a 15kg role of stainless being what it is the right choice has to be made. maybe for welding 4-6mm stainless i should move up from argosheid light, its hard to know.

 

[matt1978]

Hi Danny,

You could weld all thickness's that you mentioned with a 2-3% Co2 in Argon. You are not supposed to use any higher content Co2 when migging Stainless steel as it can lead to problems in the future. (Although I know this is the real world )

You have a Pulse machine, so you should be able to weld pretty much everything Stainless wise you'd ever need too with a 1.0mm wire and a 2-3% Co2 mix.

I put some pictures in one of my albums of Pulse mig welding with a 1.0mm wire and BOC Specshield (2.5% Co2 97.5% Ar).

 

[dannyweld]

hi matt.
so i go with the 1mm wire, i hav'nt pulsed stainless yet, only alu (and mild, could'nt see any advantage though). which wire though, 316li, 304, 308 ??. as for gas, 2-3% Co2 mix, is that argosheild light from BOC, as i'm using at present?.

 

[matt1978]

No, Argoshield light is around 5-7% Co2 and is premonimently fpr Steel.

As with tig welding the filler grade is totally dependant on the parent material Grade and post weld use of the componant, but 308 or 316 are good general wires. For mig though I would definitely recommend a Lsi type.