Stainless steel welding newbie

[robinsoncrusoe55]

Good evening everybody, I've got a one off stainless steel welding job to do, and was after some much needed advice.
I have got to weld a stainless steel support unit, the base plate, is about 3.5mm thick,
and needs a 40 mm square section support column, welders to the base plate.
I have already purchased a pack of 10 2.5mm, type 316 L, rods. The arc welder I've got,
is a Clarke, unit, with about 100 amps output.
The unit will not have to support more than 2lbs, in weight.
I have done a very limited amount of mild steel arc welding.
Where to start.........

 

[super noob]

Welds the same as mild from what I've found, plus the slag just fires off once its cool

 

[BrokenBiker]

main differences between mild steel and stainless steel electrodes that i noticed were firstly, as soon as you have finished the weld, run as fast as you can and hide behind something because the slag will fly off at speed and find the only bit of bare skin you have...secondly, while you are welding the rod will get hotte quicker than a comparable mild steel rod so you have to judge that and pick your speed up a bit more as it starts to get hot, or so i found at least

 

[BrokenBiker]

also, if you have only done a limited amount of arc welding, are you sure you are the person for the job? to get this right you will need to be able to hold a close arc, travel at the speed required and be able to focus teh heat where its needed. also, with stainless if you hang around too long you will back the parent metal and end up with a grey looking weld and could affect the area of metal that has been heat affected from what i have been told

 

[robinsoncrusoe55]

Ok thanks for that, do you think that the welder, is powerful enough, or do I need to bevel the edges, etc ?

 

[BrokenBiker]

the welder will run a 2.5mm rod, you will be looking at 80-85 amps roughly for that but its more down to you as to whether you can make a strong good weld with it, long arcing it will ruin any chance you have for this so its more down to you than the welder, you could be using a 200 amp unit and still be no better off at this point

 

[robinsoncrusoe55]

Ok thanks all, for the much needed advice, the unit is basically scrap at the moment, and if I do "cock it" up, there is no loss, as the unit would probably be replaced, probably, at a cost of about £160

 

[super noob]

Can you not TIG or mig it ?

 

[BrokenBiker]

i would prefer mig to stick, but tig is probably the way forward with it as setting up a mig for stainless for 4no 40mm welds is a bit of a hastle

 

[super noob]

I'd stick or tig to be fair.....purely because I've got access to both, as you say stainless mig is a pain to have on tap unless you run an exhaust shop

 

[BrokenBiker]

the way things are going i might just buy a tig instead of a mig and learn to use that, most of my welding is exhausts, usually for beer tokens on mk2 golfs and the like and usually welding stainless new bits to crappy mild steel original bits....tig and 309 sounds better than mig and mild wire.

anyway, back to the thread in hand, stick is doable, ive welded a few stainless gate bits together and a few stainless brackets for the kitchen my mrs used to work in (just to hold boxed stock, not in contact with the cooked foods etc) and they came out fine, but would much prefer a dedicated mig or a tig for it

 

[robinsoncrusoe55]

Sorry not got access to mig setup for stainless, or even any experience to use it !.....or tig,
purchased the rods for about, just under a fiver.....as I was not sure if I'll even get the money back for them !!!, I'm probably doing this more for my benefit, than theirs!
ie the learning curve/experience !

 

[Rrunnach]

you will not learn if you have no idea on what an acceptable, whatever process weld should look like and, whether weld is acceptable, or not. Call someone in who knows the score, you watch and learn from this, for possible future SS work.

 

[robinsoncrusoe55]

Thanks all for the really helpful advice, and tips......would really like someone, to give me one to one tuition on something, like this, but unfortunately, at this time.....it's not going to happen !
I'm considering,a mig welding course at the local college, which is a city & guilds course, and seems a way to get proper tuition, will see how it goes !
Many thanks again.

 

[Tinbasherdan]

If you are anywhere around Manchester drop by, I'll give you a crash course on stick

 

[BrokenBiker]

If you are anywhere around Manchester drop by, I'll give you a crash course on stick

this is a good offer and one that you wont be likely to find many other places

 

[robinsoncrusoe55]

Timbasherdan....... That's a really generous offer, from you, of which I am really grateful, but unfortunately, will have to say no to, as its just too far too travel for me at the present moment.
But a very big thank you anyway !!

 

[premmington]

Welds the same as mild from what I've found, plus the slag just fires off once its cool

MMA stainless self releasing slag.

Never lift your welding mask while facing a newly completed weld bead.

You cannot judge when it will fire it at you.

 

[KemppiFrog]

I do a bit of this sort of thing and, in your place, would get a few bits of scrap to get the hang of it. Your biggest problem might be the wall thickness of the tube. If under 2mm, you will probably blow holes in it. Make sure the fit is close and do short tacks to avoid heat build up and blow through. The flux on rods tends to overhang the metal after stopping the arc, so stroking the tip on an abrasive surface can expose the end for restarting the arc. Better still, do this on a bit of metal, until it arcs and then move to the joint while still hot. Cutting the rods in half can improve your control too.

 

[Tinbasherdan]

MMA stainless self releasing slag.

Never lift your welding mask while facing a newly completed weld bead.

You cannot judge when it will fire it at you.

MMA stainless self releasing slag.

Never lift your welding mask while facing a newly completed weld bead.

You cannot judge when it will fire it at you.

Yeah, it's awesome when you're in a & e having them dig around in your eye with a needle to scratch the slag out of it ....