Welding Tips and Tricks

Is it correct that if my steel is still red-hot when I finish my bead that I've traveled too slow? Meaning most of the bead is still red-hot, not just the tag end where I ended off?

And will steel that has gotten red-hot and moved out of the Argon cloud go dull? Is that a symptom of overheating steel and then letting the atmosphere get to it before it has cooled?

And is it normal for TIG welds on steel (particularly fillet welds) to be concave? Way more than aluminum?

I'm an aluminum welder and haven't worked with steel all that much. I've done some, but my main concentration as far as TIG welding goes has been aluminum. My aluminum butt and fillet welds have some body and are convex. No matter how much steel rod I shove in, my steel welds come out concave. Steel butt welds come out sunken. And I'm definitely not too hot. I'm not getting full penetration where the backside starts to fall away.

So if I'm not too hot then I don't want to drop the heat so that the bead builds up because then I risk losing what penetration I am getting.

The welds are good. The metal is joined but I don't know why I seem to always get concave.

Any ideas?

Jon

Well, it depends on a lot of things.

How thick is it? Sheetmetal turns red in a hearbeat. 1/4" steel plate, not so much.

Concave is not uncommon, it either means you are not adding enough filler or running way too hot and it's sinking, kind of like what aluminum does when you heat it up too much and it sinks through.

Gimme some settings, I do aluminum, steel, brass, copper, stainless, you name it.

Whatcha using, how are you using it, tungsten, size of the weld seam, size of your filler.

Olivero, Thanks a lot. Here are some details:

I weld with a fairly old Lincoln PT185. It's a transformer-based machine.

I weld, pretty much always, with a blue 3/32" tungsten. I grind sharp for metal and fairly blunt for AL. Seems to work for me.

Similarly, I weld always with pure Ar no matter what I'm welding. Usually running at 15-20CFH.

I spend most of my time with 3/32" filler rod. Only recently have I started experimenting with 1/16" rod to solve the "sticking in the puddle" that you may have noticed I posted about recently. That did help.

I try to hold a tight arc.

I'm not too picky, honestly, about my amperage settings. I don't, for example, work out my amperage based on the thousands of an inch thickness that my material is (I.e. 120amps for a .120 piece). I generally set my machine at 100amps and see if I can get an easy puddle to form on a piece of scrap that is the same thickness as what I'm welding. If it takes too long and barely puddles, I up it 10amps and try again. When I can get a good, fast puddle to form, I leave it at that.

I rarely use pulse. My Al setting is generally 70/30 penetration cleaning.

My post flow is about 10 seconds.

I use a foot pedal and if I see the puddle growing too big, I let off a little.

I used to have the idea that I had to stomp down on the pedal and just start motoring. And while that probably has some application, I found that on Al, if I ramped into it fairly quickly (rather than stomping down fast on the pedal) then I could get better results. Particularly when welding dissimilar sizes. Like 1/4" rod to 5/8" rod "T" joint. Or 1/4" bar to 5/8" rod with the 5/8" rod rabbet cut to accept the 1/4" bar. But either way. On that thick to thin stuff where the thin tends to blow away, I start a puddle about an inch away and move in closer until my thin piece is melting and then I add filler. I've spent hours and hours and hours blowing the 1/4" rod away by stomping on the pedal right in the joint and finally came up with this method. It's working.

On this particular weld that you asked about, I was using 3/32" all around, 70S-6 rod (that's all I've got). The piece is 1/8" thick, being welded to a piece of (galvanized) unistrut, which if I remember correctly was 1/16" or maybe 3/32". And yeah - I was coughing for a couple of days after that with the galv smoke cloud. I think the fit up was a bit loose and I had trouble with that because I had nowhere for the heat to go.

I was looking for that familiar "C" profile which lets me know that yes - I am penetrating on both sides of the fillet weld. Even then, I didn't get full penetration, meaning, there was not evidence on the backside of full penetration. Frankly, I was concerned about dropping the heat any because I felt I was barely getting that "C" profile and if I went any lower I'd just be putting melted metal on top of my piece.

So, there you go.

Probably more than you expected.

Jon