Thread: TIG welding mild steel with stainless filler rod?

Gday
Too high a gas flow can be just as bad as not enough the flow rate is roughly (depending on ceramic nozzle) 1 LPM for every ten amps up to about 150 amps from memory ,too much gas can cause turbulance pulling in air which contaminates the weld not enough and coverage of the weld will be poor also causing the weld to become contaminated so you must select the flow that best suits the conditions obviously if your outside and you have a steady breeze you must increase the flow but there is a point where it doesnt matter how much you increase the flow the wind will blow the sheilding gas away making it impossible to weld unless you set up welding
tent so your gas doesnt get blown away.
thanks caveman

Sounds like you are picking up contaminants by removing the molten wire from the gas shield after you dip it into the weld pool then introducing this contamination into the pool causing the sparking and hissing. You must keep the wire in the gas shield whilst welding and when you have completed your weld. A larger diameter cup and gas lens will make it easier to keep the wire in the shield as well. Have a look at the end of a piece of filler wire you have used, it should have a shiny molten end not dull and rough (contaminated).

It's usually the opposite way, that you will get small amounts of porosity (mill scale not ground off properly) and it will clean up with the addition of filler wire especially supersteel due to it's de-oxidising abilities!

Your flow rate of 7 to 8lpm is spot on, which is supported by the clean pool before the addition of filler.

yeah that could be another thing.... i try to keep the wire as close as possible and all the time, but im still learnin and of course I dont.....

I was welding again last night with a smaller size supersteel (i bought some more) and it was welding nicely, no splattering etc, however I did increase the flow rate to approximately 10... and using different rods (same brand as before, but different batch), AND was trying to be a bit better with my welding, keeping the wire in gas shield etc etc.

On another note, when I've finished welding, some spots are covered in a orangey-brown sort of soot... it wipes off with your finger, but i know its not good...... what exactly is that? It doesn't happen all the time, only in some spots, usually the harder to reach places.

Originally Posted by johnjohnmulley

On another note, when I've finished welding, some spots are covered in a orangey-brown sort of soot... it wipes off with your finger, but i know its not good...... what exactly is that? It doesn't happen all the time, only in some spots, usually the harder to reach places.

This sounds like you have contaminated the tungstan.
Back to gas flow- as I move around alot I get to use alot of different set-ups, I find regulators to be inaccurate most of the time. There is a flow meter available that you place on the shroud that will give you accurate readings at the shroud. As far as LPM-
find what suits you, I would not go below 10 because I dont want to risk any problems, nobody I have worked with runs lower, I'm not saying it cant be done but its not the norm.
Cheers Col.

Maybe I missed it, but I'm interested in the gas flows being suggested as I wasn't sure what to use myself and settled on 8 lpm which seemed to be working just fine (not that I'm suggesting it's right, just that it was working). However I was under the impression the gas flow varies depending on cup size, and also the material being welded, yet cup size hasn't ever been mentioned by those who are experienced in this area. Is my understanding correct, I've been using a #5 cup on mild steel.

Slightly OT, sorry, but speaking of cups how are they generally cleaned? I notice if I've been welding for a while eventually they get a bit of grunge on the inside. I'm guessing that every now and then I probably pick up a bit of contamination etc and it finds its way up in there. I'm not talking about a heap of it, just a bit but don't know if that's just one of those things in an imperfect world ie you can get the surfaces/rods very clean but something still manages to find its way there every so often. I guessed if there's so much emphasis on everything else being squeaky clean, the cups should be kept just as clean inside. I've been using a little nylon "bottle brush" looking thing, no idea where it came from.

Thanks.

Pete

G'day Pete,
8LPM- If it works for you why change it ? The basics of welding are all the same but we all do it slightly different. So some things can vary thats why youll get 1/2 a doz answers to 1 question. As for cleaning shrouds I use a rats tail for MIG so I do the same for TIG but very rearly as it doesnt get dirty for me unless Im having problems.
Cheers Col.

Hi Guys,

Was reading another welding forum and found this:
http://weldingweb.com/showthread.php?t=34250

Essentially as Col James said, 309 filler is OK according to one guy.
While 308 and 316 not so good due to cracking.