Tig Welding Failure, what am I doing wrong

[yomax4]

I will pick up a smaller tungsten and a different cup. and yes, the gas is sounds like a jet engine sometimes.

As for running reverse polarity, it did ball up the tungstend for sure but it provided a different arc. Still too strong

And I will continue with scratch start. I am just bummed that this did not work for thin stuff.

question to all, why do you tig thicker metals? What does this process provide that is not in MIG? I am assuming a cleanliness in the weld and its slow pace allows for a higher quality weld but....

"No" to Balling the Tungsten. That's old and dated AC Tig with a Transformer. Inverters are sharpened tungsten only. plus the balled tungsten gives to broad of a heat affected zone. I rarely tig over 1/8" or critical fusion of something. More practice and you'll get the tig. It's the most difficult to excel at.

 

[MinnesotaDaveChalmers]

I will pick up a smaller tungsten and a different cup. and yes, the gas is sounds like a jet engine sometimes.

As for running reverse polarity, it did ball up the tungstend for sure but it provided a different arc. Still too strong

And I will continue with scratch start. I am just bummed that this did not work for thin stuff.

question to all, why do you tig thicker metals? What does this process provide that is not in MIG? I am assuming a cleanliness in the weld and its slow pace allows for a higher quality weld but....

Thin metal is very nice with a foot control. I started tig with scratch start a few years back and once I switched to a foot control I realized I should have done it sooner.

As to why use it? Control, cleanliness, ease of switching metal, etc.
Stainless, alum, mild steel - just switch filler.

For me it's mainly about the control. No weld grinding needed, thick-to-thin is no problem, small tight welds or large heavy weld are just technique.
Guaranteed fusion - watching everything happen I know that everything was melted all the way down to the root.

High amps and larger filler speeds up tig welding a lot - it doesn't have to be slow.
200 amps with 3/32" filler or 230-250 amps with 1/8" filler will lay metal quickly.

I also mig or stick weld when appropriate.

 

[Gary Fowler]

When TIG welding thicker components that are to be xray quality, it is critical to clean between passes to remove the copper "slag" that comes off the rods and just floats to the surface. If these deposits are trapped between layers, it will affect weld quality and be rejected by xray analysis.

One reason to use TIG for first two passes on pressure piping is the ability to control the penetration and fusion to the parent metals much better than stick or MIG. The root pass is usually followed by one filler pass to thicken up the weld metal in prep for a stick rod fill. This is usually done in field conditions where MIG might cause lots of porosity or non fusion issues.
Most shop fabrication will use MIG for all passes (when allowed by the engineers or client) especially when the pipe can be rolled out with positioners at least for larger pipes. Pipe smaller than 3 or 4" O.D. might get TIG welded for root pass then MIG welded for remaining fillers or if Schedule 40 or less they may be TIG welded completely.

As a Quality Control Manager for 30 years overseeing construction of pressure piping and pressure vessels for projects in the multi-million $ to multi-billion $ cost , I can attest that with TIG you get cleaner welds and better root passes with less rejects for quality than any other process. In the hands of a skilled welder, it cost less to TIG weld a root pass than to stick or MIG weld and as for speed, TIG will beat Stick rod all day every day. MIG is a bit faster but also subject to higher rejection. When cost to repair is considered or factored in, TIG still comes out on top.

 

[breadtrk]

Gary has it right. I got certified to weld on fuel tankers up in Chicago at the pressure vessel welding deal back in the 90's. TIG takes way more practice, like a whole lot more. At the end of the day, there are no more better welds than TIG. Rockets are only built with TIG, even the launch platforms, down to the trucks and piping hauling the fuel to the pad are 100% TIG welded. Practice, practice, Practice.

Or MIG and or Stick with practice and I'll bet it holds just fine for what 97.6% of us do.

 

[spursjingles]

I'm finishing a project using 16-gage steel tubing. I use a Thermal Arc 185 Arcmaster TIG with a #8 cup, gas lens, 3/32 2% lanthanated electrode (blue color code), and a 12 CFH flow rate with Lincoln ER70S-2, 1/16 filler rod.

The general rule for steel is 1 Amp / 0.001 inch of thickness. 16-gage steel is 0.0625 in thickness - meaning the starting setting should be around 62 Amps (maximum current level). I run my welder at 65 Amps maximum, but I have both a foot pedal and a finger tip control (TIG Button made by TIG Control) to control the arc, which in turn, controls the heat input to the metal.

What I have found with thinner metals, is that if you don't have a way to control the arc intensity, the metal rapidly overheats and - you burn a hole through it. Typically, I start the weld at nearly the full pedal (65 Amps) and when I get a liquid puddle, I back off and continue the weld at about 30-40 Amps. I also use a fairly rapid travel speed, and for some joints, setup the welder in pulse mode to lower the total heat input. The pulse mode I use is 90 Amps maximum, 40 Amps background, 33% on time, and 1.3 pulses / second.

Without a way to control the arc you're going to have a difficult time managing the heat input to the metal, and puddle versus travel speed. If you're attempting to control the heat through simply using a lower Amperage setting, without a foot pedal (or other arc control) the problem you will have is that you have to dwell too long in one place to build up enough heat to create a puddle. Essentially, you're heat soaking the metal, and then have no way to reduce the heat input, so you're burning a hole through the metal.

That's why it's important to start hot and then back off the arc current as the high level starting Amperage creates a puddle rapidly without heat soaking the metal. Once you have the puddle established you can back off the arc level as the steel heats up.

Without that kind of control, it's difficult to weld thin material.

I also have a theory that the steel today must be alloyed with Chinesium which has carbon inclusions that burn through rather than melting....but, that's just my theory.

I do know that 25 years ago, the steel tubing I was welding never burned through even at higher Amperage levels...hence the Chinesium theory....

Good advice, but why aren't you using a thoriated(red)1/16 tungsten, at about 60 amps, 20 cfh.

My PowerArc 200ST runs about 10 to 15-amps hotter than any of my other welders. I've never been very good at welding that thin of material. There was a time in my life where I thought 3/8-inch thick metal was sheet metal. I think something that thin, a foot pedal would come in real handy.
Here is some Tig welds I made with my PowerArc 200ST.

Did you try upping the shielding gas flow? Also make sure it's actually flowing out the torch.
Had a problem a while back that ended up being a slightly lose adaptor on the regulator, drove me nuts for awhile until I found it when I replaced the regulator.

It was actually pulling air in and contaminating the shielding gas.