Thread: TIG Welding Galvanized Steel

I'd be cleaning much further out.

I stagger my welds because excess heat has screwed me in the past. Not just blowing holes but bending things. I never fully weld out a part straight up. If I have to do multiple passes I force myself to wait, and I wouldn't normally do multi passes on thin stuff like that anyway.

My stuff in those pics was 1.6mm thick but I was messing with pulse, so I think on that mitre butt it was 1pps, 40% on, 25% background, 72A. Fillets 200pps, 80% on, 40% background, 80A. Using the pedal on both, though. Mostly I just floor it with the pedal.

i dont have that luxury Legion

I don't normally use pulse, that was just for fun. Probably if I didn't, I'd be experimenting with 70A up fillets and ~55A on butts for that 1.6mm material. How thick was your material?

2.5mm but i dont think my cheap MIG and TIG welders are really accurate both the MIG and TIG blows holes if u ise around 70amps and a about 1/3-1/2 the voltage on the MIG

in my other thread where i had snapped around10 bolts in a aluminium outboard block i used something closes to the TIG's lowest setting around 25amps and it was melting the bolts if i wasnt too careful and quick with the filler

I would agree looking at that control panel. On mine I'd be starting at 100A for 2.5mm. And I've been as high as 140A, but moving along pretty fast and on joint configurations with plenty of material to absorb the heat.

im about to do the cross members on my job all tig so no mig, im expecting it to be very smokie so just thinking i can grind down the outsides but would a 30mm LPG blow torch burn off the galvanizing just on the inside of the tubing where i will be welding?

I don't do anything to the inside.

Alternatives:

- try burning, like you're saying, but zinc still takes a lot of heat I reckon
- use hydrochloric acid
- do nothing and deal with it

If it were hot-dipped I might try and remove it but for Duragal and Supagal light sections it doesn't affect me at all. It's probably blown away by the argon and/or arc force as it melts/boils. Just not an issue.

yeah ill give it a go i still have half a tank of argon, if its not raining tomorrow ill have a crack at it

Originally Posted by Legion

I don't do anything to the inside.

Alternatives:

- try burning, like you're saying, but zinc still takes a lot of heat I reckon
- use hydrochloric acid
- do nothing and deal with it

If it were hot-dipped I might try and remove it but for Duragal and Supagal light sections it doesn't affect me at all. It's probably blown away by the argon and/or arc force as it melts/boils. Just not an issue.

Legion - nice clear photos! nicely done. Your method is obviously working for you too. The first symptoms I get when tigging over stuff that I've supposedly removed the zinc, is that the tig arc itself will have a reddish glow/tinge to it. At this stage, the zinc doesn't seem to collect on the tungsten and it's all good. I can weld all day like this.

But I find that any decent penetration will draw too much zinc from the inside face of metal at which stage the following symptoms occur:
a) bubble of zinc on the tungsten (and erratic arc, apparent lack of amperage, etc.)
b) the weld gets a dark grey/blackish tinge to it (almost a greasy look), even though it cleans up fine with a wire brush (but who knows what's going on underneath?)
c) you get a deep crater at the end of the weld where the zinc is still fizzing out of the weld.

Gazza - if you start getting these symptoms on any critical welds (what welds aren't critical on a trailer?), then I'd urge you to grind out the weld and redo them.

Another option similar to the burn it off idea, is to run a stick weld over the joint to burn off the zinc and fill the joint (and seal the zinc inside). Then clean off the slag, wire brush, then tig over the top to neaten it out and address any weld defects? Not ideal, but I've done it before.

Originally Posted by gazza2009au

i dont have that luxury Legion

While I've never TIGed myself, I've read a fair bit about welding machines, and given that machine you have doesn't appear to have a stick/TIG switch, I imagine it's probably a challenging machine to TIG with, as it won't be running as a strict constant-current machine (which TIG needs). Rather it'll most likely have an "arc-force" or "dig" or "anti-stick" behaviour that will increase the current above the set amperage as the arc shortens, which I understand is not something you want with TIG.

Originally Posted by WelderMick

Legion - nice clear photos! nicely done. Your method is obviously working for you too. The first symptoms I get when tigging over stuff that I've supposedly removed the zinc, is that the tig arc itself will have a reddish glow/tinge to it. At this stage, the zinc doesn't seem to collect on the tungsten and it's all good. I can weld all day like this.

But I find that any decent penetration will draw too much zinc from the inside face of metal at which stage the following symptoms occur:
a) bubble of zinc on the tungsten (and erratic arc, apparent lack of amperage, etc.)
b) the weld gets a dark grey/blackish tinge to it (almost a greasy look), even though it cleans up fine with a wire brush (but who knows what's going on underneath?)
c) you get a deep crater at the end of the weld where the zinc is still fizzing out of the weld.

Gazza - if you start getting these symptoms on any critical welds (what welds aren't critical on a trailer?), then I'd urge you to grind out the weld and redo them.

Another option similar to the burn it off idea, is to run a stick weld over the joint to burn off the zinc and fill the joint (and seal the zinc inside). Then clean off the slag, wire brush, then tig over the top to neaten it out and address any weld defects? Not ideal, but I've done it before.

Mike thanks mate i have so far experienced two symptoms, 1 the crater at the end of the weld this only happy i think on one weld i was going to grind this bit off and redo it, 2 the black colour to the welds

i cant stick weld at all i really suck at it lol

Originally Posted by RustyArc

While I've never TIGed myself, I've read a fair bit about welding machines, and given that machine you have doesn't appear to have a stick/TIG switch, I imagine it's probably a challenging machine to TIG with, as it won't be running as a strict constant-current machine (which TIG needs). Rather it'll most likely have an "arc-force" or "dig" or "anti-stick" behaviour that will increase the current above the set amperage as the arc shortens, which I understand is not something you want with TIG.

Rusty its a DC stick machine but u can convert ARC to TIG with a torch and argon which mine was sold as a add on kit it seems to work ok

So it's scratch start and no remote? I'd struggle, so used to hi-freq start and pedal.

Apparently any DC stick welder is a scratch start TIG welder.

Gazza, you could cut some of those welds, even macro etch them. Even grinding out bad welds back when I did lots of stick would reveal any porosity or slag inclusion.

Originally Posted by Legion

So it's scratch start and no remote? I'd struggle, so used to hi-freq start and pedal.

Apparently any DC stick welder is a scratch start TIG welder.

Gazza, you could cut some of those welds, even macro etch them. Even grinding out bad welds back when I did lots of stick would reveal any porosity or slag inclusion.

i went over every mig welds and ground down everyone of them than i tig all joints

also it has to be aDC inverter ARC welder to be converted to tig as the older machines i learnt run on AC power


its kind of weird with my little machine running the 1.6mm tungsten i was either burning it up slowly or getting a large blob of steel on the tip and the nozzle was turning black with crap all over it that i couldnt remove so i used the only other tungsten 2.4mm? that i had with a smaller nozzle a size 5, i found the 2.4mm tungsten controlled my amps much better i could actually go up over 70amps if i tried without burning holes whereas the 1.6mm tungsten i was struggling to not blow holes

Gazza, If you're set on TIG then another technique that can help to prevent pulling zinc through the back of the weld is the use the laywire technique, where instead of dabbing the filler, you leave the filler rod in the puddle as you weld. It's sort of hard to explain in words but the idea is to make sure that you are getting full penetration with your weld (i.e. a keyhole is forming), but your filler rod is constantly sitting in the keyhole, blocking it up so that nothing gets sucked in from the back.

I was looking at your photos more - I don't get why you're not doing more grinding/clean up before you weld?