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Problems with TIG on Mild Steel

You can test your polarity is switching in the machine by switching it the opposite of what it is now and carefully add heat with pedal. As a rough guess I would go to 120 amps or so with a 1/16 tungsten- you may not need all of that to ball it up.
If it wants to ball up then you know you had it right where it was.
 
Well, my Lincoln Precision Tig 225 has an air cooled torch with one of those 'gas hose and cable in one' arrangements. Come to find out, the gas hose cracked right behind the torch handle. When I held it up right to inspect the torch and check gas flow - the crack sealed up and gas would flow through the torch. When I held the torch horizontal to weld, the crack opened up and leaked the majority of my argon out behind my hand. 🙄 once I figured it out, I replaced the torch assembly, hose and all, haven't had an issue since.
I used to have an Invertec160 sitting on my welding bench and when the fan would come on it would blow away my shielding gas. That stupid little issue took a minute to figure out.
 
The tiniest air movement ,and you are winding up the gas flow ...........I found the conditions needed for TIG to be so opressive in this climate,the sweat just drips off you,blinds your eyes ,and saturates your gloves and protective gear ....most unpleasant .........turn on the giant fan ,blow the smoke away,and Innershield weld in comfort.
 
If your set for DC TIG (DCEN) then it sure looks like a shielding gas issue. Are you welding on known good steel or mystery metal? That could be an issue as well. I was in a jam and got some junk flat bar from Lowes, that must have been Chinese recycled who knows what. Put off a horrible looking yellow soot, and the bead looked like dog turds. Also as others have already mentioned, no fans or air movement in the welding area, that'll kill the gas cloud. Since you have a multi-process welder, double check the gas connections. CO2/C25 connected to the MIG port, and Argon to the TIG port?
 
Thank you again to everyone who chimed in to suggest things for me to look into to figure out what is happening in my attempts to TIG on steel.

I tried out a bunch of the suggestions, and I have pictures below to show the results. My summary of results to date is:

1. I swapped out the hot-rolled (unknown alloy) piece that I started with and used coupons of 1/8 x 1.5 inch CR 1018. These were flap disked clean and also cleaned with acetone. The welding table surface was also wiped with acetone.

2. I disassembled the torch to show how it had been put together (see pictures below). I did not notice anything amiss. I'm pretty sure that the back cap is not bottoming out. The o-ring looked good. The connection appeared to be tight.

3. The MIG shielding gas line was disconnected at the Multimatic input port and capped. If there had been any cross-contamination between the Ar-CO2 bottle and pure Ar bottle before (unlikely), that did *not* occur in my recent tests. I purged the Ar line several times before trying any welds. Flowrate was set to about 7 LPM.

4. I tried running several beads adding filler rod (results are below). I don't think I saw a qualitative difference from previous runs in my original post. There is still a big halo of black soot around the initiation of the arc. I notice 'sputtering' during arc initiation and throughout running the bead. Is this just due to my poor technique or is the shield gas contributing to the cratering and porosity of the weld?

I had thought based on what I have seen in many videos that a TIG arc should start without sputtering, that there would be a fairly well defined puddle edge to dip filler rod into, and a clean weld area as a result. I'm seeing more of a frothy start that sputters and splashes and is still showing black brown deposits around the bead. What do you think? Certainly, I need practice, but is anything else amiss from what you can tell? Thank you!!
 

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The soot is evidence of carbon that has not been oxidized to CO2 or CO. Seems like you have carbon contamination from somewhere, and the reasonable source is the gas bottle. Is there a chance some fuel gas (acetylene, propane) got pushed into it during a different use?
 
I had an Econo-TIG that would make welds similar to that.
Finally tried a 12 dollar gas lens and it solved all problems.
Maybe there was something else wrong in the system, but the lens was the savior.

Mike
 
@rklopp Yes, it sure looks like carbon soot to me too. I was thinking that maybe the bottle has CO2 contamination perhaps from a previous fill(?). Would having that contaminant in the argon also cause the puddle to sputter?

@rustyironism I have in my Amazon cart a gas lens kit, because I was thinking that it might provide a wider, less turbulent shielding of the puddle. I'll push the button, and see if it makes a difference after it arrives.

Thank you.
 
@rklopp Yes, it sure looks like carbon soot to me too. I was thinking that maybe the bottle has CO2 contamination perhaps from a previous fill(?). Would having that contaminant in the argon also cause the puddle to sputter?.

Thank you.
But CO2 is already oxidized, so I would not expect it to make soot, which is elemental carbon.
 
I'm a big fan of gas lenses for most TIG welding, but I don't think that's the problem. I'd be switching bottles as well.

When things are correct the arc should initiate with a little pop, and sometimes a touch of wandering for the first instant depending on the joint configuration, tungsten shape, etc...but after that there should be no sputtering, buzzing, etc. It should be stable, and usually you can hear the argon flow over the noise of the arc...mostly a hiss unless you're welding aluminum since the HF is constant there.
 
  • 7 Miller cup that came with the rig and all connections were verified to be tight
  • Tungsten stickout about 1/4 in.
Too much stickout without a gas lens. Try 1/8". The cup should be so close that it's almost dragging in the puddle. Also try a No6 cup instead of the No7.

Did you try retracting the tungsten a bit then using the gas-test function of the welder (if it's got one) to check for leaks by putting your thumb over the cup? Don't try this on an HF start welder without a gas-test function, it'll hurt!
 
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I agree with comments regarding possible contamination, but I would also add one more - insufficient gas flow. I'd adjust the gas flow to supply significantly more than actually necessary for a test to eliminate that as a possible cause.
 
Too much stickout without a gas lens. Try 1/8". The cup should be so close that it's almost dragging in the puddle. Also try a No6 cup instead of the No7.

Did you try retracting the tungsten a bit then using the gas-test function of the welder (if it's got one) to check for leaks by putting your thumb over the cup? Don't try this on an HF start welder without a gas-test function, it'll hurt!
Meh the basic rule of thumb is no more stickout than the id of the gas cup, in the case of a #7 that's roughly .433". That doesn't mean shorter doesn't work, but it depends on the joint type. I've seen stickouts of over 5", granted there was copious amounts of gas poured into the crevice lol.

7 lpm is on the lower side of flow, try bumping it up a bit.

I also agree on getting a new gas bottle, it just could be it.
 
Thanks @akjeff, @plastikdreams, @crickets, @Mark Rand, @G-ManBart. I have a gas lens kit on order from Amazon, it should be here at the end of the week. I'll try some higher flows (though I had tried up to 15 LPM in previous runs, and everything looked the same (awful). If these things don't improve the situation, I'll be headed over to the supplier with my almost-full 'argon' bottle to swap it for a replacement. I hope that they will be reasonable with replacing it, but since it's taken me some time to work through all the other possibilities, I could see them saying, "Tough luck dude, you should have brought it back earlier. You're going to have to pay the full price for new fill." Have any of you had to deal with that? Thanks for your help!
 
Thanks @akjeff, @plastikdreams, @crickets, @Mark Rand, @G-ManBart. I have a gas lens kit on order from Amazon, it should be here at the end of the week. I'll try some higher flows (though I had tried up to 15 LPM in previous runs, and everything looked the same (awful). If these things don't improve the situation, I'll be headed over to the supplier with my almost-full 'argon' bottle to swap it for a replacement. I hope that they will be reasonable with replacing it, but since it's taken me some time to work through all the other possibilities, I could see them saying, "Tough luck dude, you should have brought it back earlier. You're going to have to pay the full price for new fill." Have any of you had to deal with that? Thanks for your help!
Maybe they have a gas analyzer and they can test what's in your bottle. If it's Argon/CO2 mix it should be pretty obvious. Otherwise you can just lease a smaller bottle of Argon from them for the test, in case it's not really your bottle that's at fault.
 
Thanks @akjeff, @plastikdreams, @crickets, @Mark Rand, @G-ManBart. I have a gas lens kit on order from Amazon, it should be here at the end of the week. I'll try some higher flows (though I had tried up to 15 LPM in previous runs, and everything looked the same (awful). If these things don't improve the situation, I'll be headed over to the supplier with my almost-full 'argon' bottle to swap it for a replacement. I hope that they will be reasonable with replacing it, but since it's taken me some time to work through all the other possibilities, I could see them saying, "Tough luck dude, you should have brought it back earlier. You're going to have to pay the full price for new fill." Have any of you had to deal with that? Thanks for your help!
Check the gas line from the machine to the torch for leaks. Soapy water will find them. if gas leaks out, it will pull air in. Looks like contaminated Argon to me.
 








 
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