DCEN Voltage for different materials, GTAW
DCEN Voltage for different materials, GTAW
(OP)
Hello:
I seem to recall a chart of recommended voltages when GTAW steels. I can not seem to find it anywhere, anybody have a link to it?
Typically 300 SS was around 9.0 DCEN. The specific reason is that we are Welding Inconel 718 and are getting a 50%fallout from X-Ray. Inclusions mainly. I believe our welders are "boiling" the puddle. The Voltages are at 12.5 VDC up to 13.5 VDC. He is weaving a 1/2" wide bead on plate material that is .125 thick. I am unable to locate the original WPS, not sure one was even generated.
Someone suggested using Argon-Hydrogen at 2.5% ??
Thanks for your advise in this matter.
I seem to recall a chart of recommended voltages when GTAW steels. I can not seem to find it anywhere, anybody have a link to it?
Typically 300 SS was around 9.0 DCEN. The specific reason is that we are Welding Inconel 718 and are getting a 50%fallout from X-Ray. Inclusions mainly. I believe our welders are "boiling" the puddle. The Voltages are at 12.5 VDC up to 13.5 VDC. He is weaving a 1/2" wide bead on plate material that is .125 thick. I am unable to locate the original WPS, not sure one was even generated.
Someone suggested using Argon-Hydrogen at 2.5% ??
Thanks for your advise in this matter.





RE: DCEN Voltage for different materials, GTAW
The amperage is what I would check. The nickel alloys can get a little sluggish and weaving has not worked well for me when welding by hand.
I have no experience with 718 so it may be a different creature.
Gerald Austin
Iuka, Mississippi
http://www.weldingdata.com
RE: DCEN Voltage for different materials, GTAW
RE: DCEN Voltage for different materials, GTAW
Constant current power supplies are used with GTAW. Arc voltage is a function of tungsten tip to work disatnce, amperage and shielding gas type. Without Automatic Voltage Control(available on automatic equipment), the arc voltage will fluctuate as the welder manipulates the electrode and it would be highly improbable for a welder to maintain 9V without sticking the tungsten, resulting in a tungsten inclusion.
The flaws defined are workmanship flaws, which can be mitigated with increased training, changing shielding gas to Argon-Hydrogen or Argon-Helium mixes, decreasing weave, shape of tungsten tip, and quality of shield gas.
RE: DCEN Voltage for different materials, GTAW
Arc length will determine the arc voltage and it will vary as the welder either lengthens or shortens the distance between the end of the tungsten and weld puddle.
Voltage will also vary if the shielding gas is changed.
A small percentage of hydrogen (5%) may be added to the Argon to increase penetration, but it will not do much for the fluidity of the puddle. Nickel is like toothpaste in the puddle. It doesn't wet out like carbon steel and simply increasing the amperage does little to help.
This is where stringer beads will result improve the appearance of the bead. Be sure to clean between each weld pass. Wire brushing is not aggressive enough. You will need to use a carbide rotary file (burr) or grinding disk. Don't bear down hard, just enough to abrade the surface to break up the surface oxides. Wire brushing will "shine" the bead, but it will not break up the oxides. If the oxides are not removed between passes, it will build up with each successive bead and the weld will wet in less and less.
Good luck.
Best regards - Al
RE: DCEN Voltage for different materials, GTAW
Gerald Austin
Iuka, Mississippi
http://www.weldingdata.com
RE: DCEN Voltage for different materials, GTAW
http:/
http://www.millerwelds.com/resources/TIGhandbook/
hope this help
S
Corrosion Prevention & Corrosion Control
RE: DCEN Voltage for different materials, GTAW
I am looking for a more pro-active test to confirm successful brushing.
We changed to stringer beads and they are helping with his consistency of the arc gap and subsequent voltage.