First go of Stainless Tig Welding, Advice please.

[joeeng]

I have just had a go at tig welding stainless for the first time.

R-tech ac/dc tig 160
amps 130.

First attempt is the pics with more carbon buildup and discolouration also the tungsten needed cleaning.

Second attempt I was trying to use the pulse more to control the heat.

no filler rod used on either attempt

any advice welcome

 

[Richard.]

Use filler particularly for the above joint been a fillet. A throat thickness is needed to reinforce it with strength and you will have deep undercut there too as your not replacing any of the parent metal that you've used to fuse the two pieces together. There isn't much to comment on it regarding how well it's done because I'm afraid it's not done correctly.

 

[joeeng]

Use filler particularly for the above joint been a fillet. A throat thickness is needed to reinforce it with strength and you will have deep undercut there too as your not replacing any of the parent metal that you've used to fuse the two pieces together. There isn't much to comment on it regarding how well it's done because I'm afraid it's not done correctly.

Thanks for the feedback richard, I will have another go with filler, am I in the correct range amps wise (130) , the flat plate is 8mm thick, I am running 13lpm gas which seems a bit high from reading other posts as 7-10 lpm seems normal.

 

[Richard.]

Yeah 130-160 would be a good range given its chunky stuff. Don't bother with the pulse though! There is no place for it on material anywhere near that thick just hit it with a flat current. 2.4 tungsten ground to a point 2mm filler. I use gas lenses for everything especially stainless so my flow rate doesn't need to exceed 6lpm. 13 is just giving it away and too much can effect the weld in the same way as too little* 10 is too much too if your using collet bodies 6-8 lpm is ample.
* excessive flow rates can act in a way that causes turbulence and suck air in to your coverage causing contamination in much the same way as not enough can. It's a double negative because not only are you wasting gas your also not getting the protection you need which compromises the weld and contaminates the tungsten.

 

[joeeng]

Yeah 130-160 would be a good range given its chunky stuff. Don't bother with the pulse though! There is no place for it on material anywhere near that thick just hit it with a flat current. 2.4 tungsten ground to a point 2mm filler. I use gas lenses for everything especially stainless so my flow rate doesn't need to exceed 6lpm. 13 is just giving it away and too much can effect the weld in the same way as too little* 10 is too much too if your using collet bodies 6-8 lpm is ample.
* excessive flow rates can act in a way that causes turbulence and suck air in to your coverage causing contamination in much the same way as not enough can. It's a double negative because not only are you wasting gas your also not getting the protection you need which compromises the weld and contaminates the tungsten.

Thanks again for the advice Richard,

I had a play about of a few bits the other day and trying different settings. I found that with 130amps the work got too hot and I ended up with dull welds (this is probably due to my slow speed and in-experience) I found that with 110amps I was able to get penetration and a reasonable colour.
this was using a 2.4 tungsten (sharpened using hudmuts grinder which is brilliant) a No.8 cup with 7lpm gas flow and used a 2mm 316L filler rod.

dont have any pics of the final pieces I done, as I was busy at work, Hopefully will have time to get my welder set up at home and get some good time practicing.


a couple of things I am unsure of is

How to work out suitable gas flow for each cup size.

Best amps when welding thin stuff to thick eg, 2mm wall box section to 8mm rod??

(The photo is just a bit of practice I done trying different settings 2mm wall box section on the left and solid bar on the right) The long vertical bead on the right piece was what I thought was better than the rest.

I will do some better practice pieces at home with settings labelled)

 

[Richard.]

You shouldn't need to adjust flow rates to cup sizes unless your going massively big which is just not needed.
Thick to thin is pretty much the same current level as thick to thick. Always set the current to your thickest section and when welding concentrate your pool focus on the thickest section but allowing it to wet the edges on the thinner piece.

 

[Brad93]

It's more about gas flow through a standard collet body than the size of the cup, for example I'm using around 5lpm through a size 5 standard cup and keep that figure when I change to a #6 or #7. You could go up to 6 or 7 lpm for stainless if you're looking for silver or straw coloured welds, i use around 4lpm for mild steel. Remember Torch angle, heat input/travel speed make a big difference on stainless. No doubt at 10lpm on a standard collet body you're going to be getting eddy currents/turbulence which will actually cause contamination.

Can't really give any further advice that hasn't been covered by Richard and I don't do any ss over 1.5mm

 

[Richard.]

Strive for shiny. It doesn't matter what colours you get regarding heat tint as you'll remove these on a job any way by picking and dressing. A grey weld isn't great but at least it's well fused and better than a very shiny run that's too cold and not penetrated/fused properly so don't worry too much as its the lesser of two evils. Dull welds do polish up ok in some cases which is what stainless is all about. The key is finishing it properly.

 

[joeeng]

Thanks, everyone for the help, I will take this onboard and hopefully have a good bit practice on the weekend. starting with the basics on flat plate etc and see what feedback you can give me from there.

Joe

 

[Brad93]

Sounds good Joe. Sorry forgot to say all my welds get ground out and painted over so if they come out a bit dull it really makes no odds.

 

[eSCHEn]

Torch angle [...] make a big difference on stainless

Hope Joe doesn't mind but would you elaborate on that a bit Brad? Is it a case of striving for a nice, tight close to 90° angle on to the job to try and minimize and focus the heat input?

 

[Brad93]

I find a bit of angle on stainless best to be honest, but yes always tight arc length.
After all you want to push the puddle along a little bit. I haven't got any thick stainless to hand to mock anything like the above joint up but I have got some box section and mild steel rod so will go have a quick play.

 

[Brad93]

So here we go

304 25mmx2mm box
M/s 10mm bar

 

[eSCHEn]

I find a bit of angle on stainless best to be honest, but yes always tight arc length.
After all you want to push the puddle along a little bit. I haven't got any thick stainless to hand to mock anything like the above joint up but I have got some box section and mild steel rod so will go have a quick play.

I've strived for a "best perpendicular" to the job sort of angle. I think because gas was my first process I have a tendency to "flow" the metal with the arc which I shouldn't so I make a conscious effort to stop myself and end up straight on.

 

[Brad93]

Bit of undercut on the bar, not entire sure its plain steel to be honest, but yeah that was welded on the pedal set at 70 amps so imagine I was using 50-60 amps on that.
Still some colour even though it's steel to stainless welded with 1.6 308L.

Done some practice beads on the box in my opinion there is literally no difference between running the #6 cup and Collet body at 5lpm then running at 7lpm. What I did to simulate a swith I set the current at about 40 amps and nailed the pedal.

 

[Brad93]

With the torch angle someone such as Hotrodder, Richard or @Paul. will be able to advise best they've done a lot more stainless than me. I generally only do up to 1.5mm mostly boxes with small brackets so outside corners and small fillets not really and round to flat.

 

[joeeng]

Bit of undercut on the bar, not entire sure its plain steel to be honest, but yeah that was welded on the pedal set at 70 amps so imagine I was using 50-60 amps on that.
Still some colour even though it's steel to stainless welded with 1.6 308L.

Done some practice beads on the box in my opinion there is literally no difference between running the #6 cup and Collet body at 5lpm then running at 7lpm. What I did to simulate a swith I set the current at about 40 amps and nailed the pedal.

Thanks for the example brad, much neater than what I am capable of at the minute. just with regard to what richard said about setting the amps for the thicker material. I struggled to do this and ended up with holes in the 2mm box at 130A. I need to practice my pool control more to bring it down gently on the thinner stuff. did you find 50-60amps a limit as in any higher and it would be too hot or was it just personal preference?

 

[Richard.]

Welding 8mm plate to 2mm plate yes?
I'd certainly be up to 100 plus, slightly less for round bar like above because it becomes heat soaked quicker. focus the arc directly on the thicker plate as you add filler allow the pool to wet onto the 2mm. If you try to focus the arc onto both pieces you will likely go through the thinner material. The optimum torch angle is pretty much perpendicular to the work. We put an angle on it of 10-15 degrees so that we are able to see what we are doing but the angle is slight so that you still keep the tight arc and even coverage from the gas. Any body can join two different thicknesses with a current set toward the thinner piece but then your not fusing the thicker section properly and it's a weak joint. Try different current settings till you find one that works then attempt to break it. See how it goes.

 

[Richard.]

Joe can you tell me the exact joint your asking about and I'll draft up some settings that work.

 

[joeeng]

Joe can you tell me the exact joint your asking about and I'll draft up some settings that work.

This is what I am trying to do, the 10mm loop has a small flat filed on the bottom so it sits square on to the 2mm box section. as you can see I burnt away the edge of the box section. it didnt look pretty before I ground it back, i done this by doing spot welds basically but would like a full weld around the piece due to its use.

I think I done this at 50amps, 2.4 tungsten, 7lpm, No9 cup, 2.0mm 316L filler