- tig weld.JPG (145.25 KiB) Viewed 659 times
Just started running my first beads this week. This is one of the better looking ones. I keep getting these holes in the bead. Not sure if it's too much or too little gas. Settings are 70 amps DC, 10 CFH of argon, 1/16 tungsten and 3/32 filler rod, steel is .125". Also the beads all have a dull appearance. Many of the ones I see online have a shiny look. Is this a gas problem?
Looks like contamination in the base metal itself. If so, you may not be able to avoid it. Some metal is just not all that great a quality for welding.
Miller ABP 330, Syncrowave 250, Dynasty 300 DX.
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- Otto Nobedder
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TamJeff may be right... It's easy enough to try with different steel.
10 CFH is adequate in dead calm air, but is lower than typical, so this is a place to experiment. Depending on application, it not unusual to see up to 35 CFH, though I normally never go above 25. Additionally, looking at your bead, you may have too much torch angle, especially for a low gas flow rate. You might try a short bead with the torch at dead square to rule this out.
The only other likely culprits are contamination of the rod (is it clean and rust free?), contamination of the gas (impurities or moisture, or both), or a leak in the gas line downstream from the flowmeter that can draw air into the flow.
Steve S.
10 CFH is adequate in dead calm air, but is lower than typical, so this is a place to experiment. Depending on application, it not unusual to see up to 35 CFH, though I normally never go above 25. Additionally, looking at your bead, you may have too much torch angle, especially for a low gas flow rate. You might try a short bead with the torch at dead square to rule this out.
The only other likely culprits are contamination of the rod (is it clean and rust free?), contamination of the gas (impurities or moisture, or both), or a leak in the gas line downstream from the flowmeter that can draw air into the flow.
Steve S.
Thanks for the input. I did clean the mill scale off but forgot to wipe with acetone. I think it was the Miller site that recomended 10CFH at that level of current. I checked out several welding sites and gas flow recomendations all vary greatly. I will up it and also check the torch angle. I did check all the fittings on the argon lines and everything is tight.
Peter.
P.S. I think you are wrong about air being drawn into the line at a leak. For the argon to flow out of the torch it's pressure has to be above atmospheric, otherwise when the valve opened air would flow in to the line instead of gas flowing out. Any leak in that system would allow argon to escape before reaching the torch giving you a lesser flow at the torch than indicated at the flow meter.
Peter.
P.S. I think you are wrong about air being drawn into the line at a leak. For the argon to flow out of the torch it's pressure has to be above atmospheric, otherwise when the valve opened air would flow in to the line instead of gas flowing out. Any leak in that system would allow argon to escape before reaching the torch giving you a lesser flow at the torch than indicated at the flow meter.
- Otto Nobedder
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That's a common misconception, and seems to fit comon sense.
The gas line is subject to dynamic pressure, like the venturi effect in a carburetor, which can lead to air being drawn in. It's more common on water-cooled torches where the "gas valve" is a solenoid in the machine, rather than a knob on the torch, but if the knob is open for full flow from the flowmeter, the static pressure can still be overcome by dynamic pressure, particularly at connections, where the cross-section may be reduced, accelerating the flow further.
If you've checked the line end-to-end, you can rule this out, but it is always something to check for when you have porosity problems.
One other thing I once encountered was contamination of the tungsten... Someone had used penetrating oil near my machine, and I had several sharpened tungstens on top of the machine. It took a while to figure this one out, as there was no visible sign on the tungsten. I was able to clean the ones I hadn't used. I discarded the ones I'd tried, as the oil was now "baked on". (I don't think this is your problem; What I saw was widespread discoloration of my weld, and microporosity on the surface. It's just an example of the odd things that can go wrong.)
Please post when you find the problem; We all learn from each others' problems and solutions.
The gas line is subject to dynamic pressure, like the venturi effect in a carburetor, which can lead to air being drawn in. It's more common on water-cooled torches where the "gas valve" is a solenoid in the machine, rather than a knob on the torch, but if the knob is open for full flow from the flowmeter, the static pressure can still be overcome by dynamic pressure, particularly at connections, where the cross-section may be reduced, accelerating the flow further.
If you've checked the line end-to-end, you can rule this out, but it is always something to check for when you have porosity problems.
One other thing I once encountered was contamination of the tungsten... Someone had used penetrating oil near my machine, and I had several sharpened tungstens on top of the machine. It took a while to figure this one out, as there was no visible sign on the tungsten. I was able to clean the ones I hadn't used. I discarded the ones I'd tried, as the oil was now "baked on". (I don't think this is your problem; What I saw was widespread discoloration of my weld, and microporosity on the surface. It's just an example of the odd things that can go wrong.)
Please post when you find the problem; We all learn from each others' problems and solutions.
Landyman
- Landyman
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I've always tried aiming the torch at my cheek to feel how much gas is coming out for a couple of reasons.
One is because in one of the bays a welder had a slight mishap when the mig welder's gas cylinder fell over and smashed the flow tube off the wall for the plumbed in argon for the tig welder. It was replaced by an 'experienced(?)' welder of many years in the horizontal position, so the 'bucket' just lies there giving no indication what the flow might be. Another is because in most of the other bays the flow meter is bolted to the wall and in a couple of them the scale is FACING the wall, and the other is i wouldn't have a clue what it is supposed to be anyway.
A colleague uses the same 'blow on the cheek' method, but be warned, if you hold the torch too close to your face it can arc through your cheek against your fillings!
Apparently, it stings MORE than a bit and leaves a REALLY NASTY taste in your mouth for a couple of hours! He says...
One is because in one of the bays a welder had a slight mishap when the mig welder's gas cylinder fell over and smashed the flow tube off the wall for the plumbed in argon for the tig welder. It was replaced by an 'experienced(?)' welder of many years in the horizontal position, so the 'bucket' just lies there giving no indication what the flow might be. Another is because in most of the other bays the flow meter is bolted to the wall and in a couple of them the scale is FACING the wall, and the other is i wouldn't have a clue what it is supposed to be anyway.
A colleague uses the same 'blow on the cheek' method, but be warned, if you hold the torch too close to your face it can arc through your cheek against your fillings!
Apparently, it stings MORE than a bit and leaves a REALLY NASTY taste in your mouth for a couple of hours! He says...