Stainless tig welding - 1.6 mm to 1.6 and 2.4

[manticle]

I know there's a few experienced welders on here.

Any tips or recommended settings for sturdy welding of small diameter stainless to either same diameter or slightly thicker?

Had a crack yesterday and today and some came up ok but struggled to get a weld pool that wouldn't melt the thin parent too much before applying the filler.

This is to make object mounts for museum objects so imagine a 4mm post, perpendicular butt a 2.4 at the end (t-shape) then perpendicular butt a short 1.6 at each end of the 2.4 (bit like a thin camping toast fork).

Have amp settings down low (I was on 25, colleague had more success below 20) and using 2t so I can have the arc stop after a tiny time with minimal effort but struggling to get a neat, sturdy weld I can trust.

Possibly odd request, have other avenues for advice but the more, the merrier.

 

[Camo6]

Not an expert but have dabbled with thin stainless.
What size tungsten, cup size, gas flow etc?
Is it HF, scratch or lift start?
Are you starting the weld pool on the thicker metal and flowing to the thinner?

I'd be aiming for, atmost, a 1.6mm thoriated tungsten, low gas flow, low amps and focus on the thicker metal before introducing filler and moving to the thin.


Oh, also make sure your tungsten stays nice and pointy to get right into the corners. A gas lens allows you to extend your tungsten if access is tight.

 

[manticle]

1.6 tungsten. HF. Can't remember cup size but one of the smaller ones from the torch kit.
Gas flow probably 10-ish so could drop, straight argon. You reckon maybe 6-8 L/m?

Tungsten sharp.

Trying to melt parent material first - main issue is getting it just right. Can get 2.4 onto 4 easily enough but getting 2.4 pooling but not burning through so I can add the 1.6 is tricky. If it burns through, I have to start again. Needs to be millimetre perfect, no failure points.

Also trying to weld 3 x 1.6 prongs onto the end of a 4mm post - 2 is easy enough but number 3 often melts off one of the others. Maybe patience and cooling the work between welds is the way forward?

Also should I push the electrode almost inside the hood? Been protruding maybe 3 mm.

 

[Camo6]

I bought a cheap set of gas lenses off fleabay that basically provide a better gas blanket allowing you to extend the tip giving you more control and visibility.

Sounds like your approaching it right. I'd definitely let it cool between welds, maybe even use a heatsink if practicable. If you can turn the amps down a bit you can probably work your pool a bit longer without burning through.

You might need to fiddle with your ramp settings to avoid too much initial heat but I don't have the expertise to advise. Might be a bit of trial and error until you get it right. Have seen razor blades joined so can't be that hard!

Hopefully some more qualified melders of steel can chime in.

 

[manticle]

Thanks camo

 

[Lyrebird_Cycles]

If they are mounts why don't you braze them? Much easier to do with small diameters since the parent metal stays solid, in practice it's just as strong as a weld*.

Harris 56 with their white flux is the standard recommendation for stainless, it works well as long as you maintain good gap clearance (it won't fill beyond about 0.2mm). You should be able to order that through your local welding supply.

Cycle Designs System 48 with the system flux or their "stainless light" flux is excellent, flows almost as well as Harris 56 but will fill a small gap. Best to order direct from the US, there is an Australian agent but he's useless.

You'll need to mitre the joints but the easy way to do that for such small diameters is by drilling: drill a 2.5mm cross hole near the end of the 4mm rod, push the 2.4mm rod through, braze it in place then grind off the end of the 4mm rod where it protrudes past the cross piece.

The other way to mitre small joints like that is a dremel with a carbide burr, I regularly use a 2.4mm, I think they also make a 1.6.

For the 3 x 1.6mm to 4mm butt join: dry fit everything and wind a short piece of 1.6mm Titanium filler wire around it to hold everything in place. Flux it up and braze it then unwind the Ti wire. Standard brazing alloys won't wet Ti.


* Depending on alloy: the HAZ on a braze is larger but since it was never melted it usually stays stronger.

Edit: Something you could try is to set the joint up as recommended under drilling above then fusion weld it with TIG (no filler). You could strike the arc on the bit you are going to grind off, work down until the joint fuses then back up straight away.

 

[manticle]

Brazing is how they are normally done I believe.

I'm quite new to this aspect of my job and while I have some limited experience of mig, tig and stick, I only have experience with oxy cutting, not brazing.

I have been led to understand the tig should do what I want as well as oxy so I wanted to work out how.

Had wondered about fusion tig welding, wasn't sure if it would work, need to be 100% sure that what I do will work.

Fortunately there's people smarter and more experienced than me working on this too.
Thanks for the ideas and tips.

 

[Lyrebird_Cycles]

The key to both brazing and fusion on stainless is surface prep. Both the surfaces must be completely clean and scale free so they will wet without inclusions.

Abrade the surfaces with Beartex pad, wipe with a clean paper towel and acetone, get to work.

 

[manticle]

Yeah been cleaning with sandpaper and ethanol.
Not acetone yet though. Will pull it out from our chemical cabinet tomorrow. Will take the time to drill and fit.

Think I've been trying to rush due to the volume of work and limited time* but short cuts make work harder and take longer.

*and inexperience which leads to frustration when you want to be better than you really are.

 

[feralbass]

IMO, put your amps up a bit, I would be using 40 plus, gas flow 10 -16 ltrs, large dia cone.
Very sharp electrode, 1.5 mm filler wire.

 

[manticle]

Just fusing/autogenous on very low amperage is working well today for welding the 1.6. Also 2t rather than 4 helps.
Fiddly and frustrating and little room for error but much neater than yesterday.

2.4 is fine with 1.6 filler and low amps.

Cheers all.

 

[malt junkie]

Welding is all practice and persistence, I haven't picked up a torch in nearly 20 years, I was a hack back then, and dare say I'd be worse now. Keep at it ... I'm going to need someone to weld my kettles one day.