Thread: TIG welding mild steel with stainless filler rod?

Gidday John

BEfore we go into this one can you tell us a bit about your setup namely

What tungsten are you using
What Gas Flow rate are you using
What type of gas are you using
Whats the type and thickness of the material your trying to weld
Are you welding with AC or DC current

REgards Lou

It is fine to weld mild with stainless filler but not stainless with mild fillerso if welding mild to stainless then stainless filler is the reccommended. as far as filler wires go I have found that stainless mig wire either 0.9 or 1.2 mm is superior to most rods on the market.. hope this is useful for you.

Originally Posted by johnjohnmulley

As per title,

Also welding mild steel to stainless steel, what filler rod is recommended?

309 is the norm. If your not worried about S/S rusting mild steel filler is fine.
Are you only having problems when you are adding M/S filler, if so, it sounds like the wire may be dirty. Did you buy it or was it given to you? It may not have been stored coorectly. If you have some material left over from the job, cut a thin piece off and use that as your filler. Its a process of elimination!

Thanks for the replies

Tungsten:
2% thoriated 1.6mm and 2mm (trying different ones)
Gas flow:
8lpm Argon
DC WELDING
Welding roughly 5mm plate to 2mm plate mild steel


2nd question
I have used mild steel rod (supersteel the guy said) brand new from welding shop and used it the same day. I dont know how easy it is to "contaminate" the rod, but I just picked them up wtih my hand, and used them straight away after sitting on my car seat... They just seem to hiss and splatter and weld very badly, which is why im asking if i can use s/steel welding filler rod to use instead because its much nicer. I am just wondering about the structural aspects of it?

I guess what would be better is, why are my mild steel rods like that? Would they be a bad quality? Or is that just what they do? I have no need to use the s/steel filelr rod, just for the fact its much nicer to weld and to me seems stronger to weld with as it isn't hissing and splattering and to me that means the weld will have lots of porosity in it..?

Cheers
John.

PS
it's ok to use mig wire? I assume its all the same stuff in the end? So buy a small roll of s/steel mig wire and use that instead as filler rod?

mig wire is fine just do not use flux core wires I have done quite a bit of tig welding of all metals Aluminium, stainless mild etc. your thoriated tungstens should be fine on mild steel if you think the rods are the problem just try welding the mild steel without any filler rods (it will work) as this will eliminate wether or not the rods are the problem or as was stated by someone else before try an offcut slither of scrap in this case it would be the 2 mm stuff. As i stated previously i have found mig wire to work better than most of the commercial filler rods and have achieved very strong and acceptable welds using this method. for mild steel mild mig wire will work quite well but for stainless I would definetly recommend stainless filler. To tell the truth I have had to use fencing wire a couple of times welding mild and it worked fine.

oh and on those supersteel rods take them back to where you bought them and let the guy know what you think of them, Personally I have never heard of them and to be honest I would be sceptical about them if they hiss and spit a tig should weld smooth without spatter. As a reccomendation if you are to buy filler rod i would reccomend only buy it if it has the BOC or Cigweld labels on it in australia. (there are a couple of other good brands but these are always reliable and a good place to start.)

Go right ahead,but its an expensive way to go.
Ask yourself why is the professional tig welding community are not doing this.The reasons are many and varied,but cost and metal mismatch will figure greatly.

Hi test or equivalent s what you should be using.They are double de-oxidised filler rods

If the filler rods are clean and free of grease and and rust,
the problem is elsewhere.

8 LPM is too low ,you need bugger all breeze to end up with contamination for the atmosphere. 14lpm has been the standard setting for years.
If not a gas cover issue I would be looking at parent plate contamination-oil grease ,paint or rust.


Supersteel are the old LW1 triple de-oxidised and were a top of line Tig filler as would be used in boiler tubes and chrome moly work.

GRAHAME

Its me again.
Something just popped into my head.

Years ago I had a similiar problem .It turned out that in my zest to clean the plate off with a wire buff-The air oil mix blew all over the plate-The plate was oil conaminated and while I wiped i with a rag it was enough to give trouble.Maybe a good clean clean down may help.

Watch your solvent -some of the brakekleen products heated by the UV rays have been known to turn into phosgene.Very nasty and could make you a really sick puppy. I seem to remember Trichloroethlyene has been the nasty in the compound.

Metho is ok to clean with

Maybe give the filler wires a clean up with steel wool and metho to get any crap off them.

Grahame

Thanks

few more questions, and don't take these the wrong way i know you're the welding technologist.

I read on a few websites, and one was the "miller tig handbook" which i assume is a fairly respected brand of tig welder... the rate of argon gas flow is between 15-20cfm, which relates to 7-9.5LPM. I know it depends on a lot of other things such as gas cup size, amperage, conditions etc, but why do you say 8lpm is too low? Is it really too low, or just the higher the better...

So are you saying supersteel, the type of rod I supposably have, are "top of the line" ?

The steel I was welding was fresh from the steel merchant, I just sanded back to bare metal with an angle grinder I could nearly see my reflection in it... is that ok? Or am I meatn to hit it with some sort of liquid wash to get all oil off it?

When I was welding the two steel plates together without filler rod it would weld beautifully, as soon as I started using filler was when it started to hiss and splatter and bubble, so i'm pretty certain it wa sthe filler. Maybe i contaminated it with my dirty gloves, but why didn't this happen with the stainless filler if that was the case?

Lastly, you said cost is a major concern, for the few jobs I'll be doing, it will make all of a few dollars difference. I'm interested in the structural aspects, welding mild steel to mild steel, with a stainless filler, would that be less strong than using a mild steel filler. I'm assuming it would be, as the microstructure would probably make it easy for cracks to form? Thats a huge random guess so help me here

Thanks for the replies

S/S filler shouldnt be used for high strength welds for a number of reasons. But for say a table leg no worries. The main factor would be the cost of S/S.
I'm with G.C. with the gas I wouldnt go under 10 lpm. What sort of gauge have you got? Ball type are the most accurate. Still, after what you've explained it does sound like the wire is the problem.
Cheers, Col.

Originally Posted by Col James

S/S filler shouldnt be used for high strength welds for a number of reasons.
Cheers, Col.

I'm going to be like one of the annoying school kids here and keep asking...

"what are the reasons behind it"

Originally Posted by Col James

What sort of gauge have you got? Ball type are the most accurate.
Cheers, Col.

I've just got a regulator with two gauges, one shows pressure, the other gauge shows the flow rate. It's not like a ball type where it goes up and down with the flow rate. It's just shown on a dial... I just got it from a welding shop here in brisbane....

Thanks for the reply

Gidday

Um yeah well to be honest i'd forget all that yeeeeeeeeharrrrrrrr bout weldin with Mig Wire Stainless n the like ..................... and match your filler rod to the metal your trying to weld.

In a nutshell Grahame is letting you know and im definately concuring that your filler rod is appropriate and if used correctly will result in an excellent weld.

I'd also recommend ramping up the GAs flow to 12-14 LPM.

Heres Millers problem solver in regards to typical hassles you can come across when firing up your Tig:

http://www.millerwelds.com/resources...eshooting.html

My moneys on your gas flow being to low..................but is more likely that the culprit is along the lines of Mr Collins suggestions

The best advice I can give to get the best results consistantly is to follow the recommended procedure......................

LEt us know how you get on

REgards Lou

I'd suspect the filler rod is the problem.
You're only seeing porosity with the mild steel rod and not the stainless rod.

Plus I run at 7 LPM and haven't had a problem and that's the rate I was taught at TAFE. Possibly the other guys are talking in CFM.

Clean your rods off with scotchbrite pads. It never hurts to do it.

As others have said, you can try using slivers of the parent metal as a substitute rod and check for porosity. If none, you can blame those rods.

Check out the example pics here to see the difference between dirty materials and poor gas coverage:
http://www.millerwelds.com/resources...-guide-graphic

I' ve never tried stainless rods with mild steel, so I'm interested in what the potential problems could be.

Originally Posted by johnjohnmulley

I read on a few websites, and one was the "miller tig handbook" which i assume is a fairly respected brand of tig welder... the rate of argon gas flow is between 15-20cfm, which relates to 7-9.5LPM. I know it depends on a lot of other things such as gas cup size, amperage, conditions etc, but why do you say 8lpm is too low? Is it really too low, or just the higher the better...
...

Lastly, you said cost is a major concern, for the few jobs I'll be doing, it will make all of a few dollars difference. I'm interested in the structural aspects, welding mild steel to mild steel, with a stainless filler, would that be less strong than using a mild steel filler. I'm assuming it would be, as the microstructure would probably make it easy for cracks to form? Thats a huge random guess so help me here

Hey Edster, cool link. Im pleased to say the only one of those faults I have seen in my welding has been improper arc length.

John - are you welding inside or outside? So far I have only welded indoors, on 10 litres per minute (ball gauge). Have never had a prob. The only time I got rods splattering was when I was using some oxy filler rod to practice when I very first got the welder. Unlike proper mild steel filler (such as what you bought) its unprotected by copper and you can virtually watch it rust. Once I was being lazy and kept welding past the clean part of my oxy filler rod (i sanded the rust off) into a rusty part. It started spitting immediately.

Maybe you could try cranking the gas flow up and persisting with your current rods..if they still spit, i would be taking them back.