GMAW-P on P4 Material
GMAW-P on P4 Material
(OP)
Does anyone here have experience using a pulsed GMAW process on P4 (Gr. 11, 12) material?
Using Lincoln equipment and running a downhill technique, we were unable to get a porosity-free weld using ER80s-B2 wire and a 90/10 Ar/CO2 mix.
When running the same process and comparable parameters on carbon steel with ER70s-6 wire, we could achieve perfect welds every time.
However, once the ER80s-B2 wire was used, we could not achieve a sound weld any time we ran over previous passes. No problems with an open root, but any time we pass over existing weld metal, even when ground/smoothed to bright, clean metal, we get porosity that is not open to the surface. We see it sporadically where the weld interfaces with the previous weld metal, and other times right in the middle of the weld bead. When running an open root pass, we did not see any porosity in that part of the weld, but would see porosity/inclusions when back grinding and welding the other side, or when welding the hot and fill passes.
We got the same results in the flat position, trying the ER80s-B2 wire on both carbon steel plate, and the P4 plate. We tried different heats of wire, different manufacturers, different gas bottles, different torch angles, different pulse wave forms, different flow rates, different interpass temperatures, different cleaning techniques... none of which eliminated the porosity/inclusions.
Needless to say, I'm baffled as to what the cause of this may be. Does anyone have any suggestions or input?
Using Lincoln equipment and running a downhill technique, we were unable to get a porosity-free weld using ER80s-B2 wire and a 90/10 Ar/CO2 mix.
When running the same process and comparable parameters on carbon steel with ER70s-6 wire, we could achieve perfect welds every time.
However, once the ER80s-B2 wire was used, we could not achieve a sound weld any time we ran over previous passes. No problems with an open root, but any time we pass over existing weld metal, even when ground/smoothed to bright, clean metal, we get porosity that is not open to the surface. We see it sporadically where the weld interfaces with the previous weld metal, and other times right in the middle of the weld bead. When running an open root pass, we did not see any porosity in that part of the weld, but would see porosity/inclusions when back grinding and welding the other side, or when welding the hot and fill passes.
We got the same results in the flat position, trying the ER80s-B2 wire on both carbon steel plate, and the P4 plate. We tried different heats of wire, different manufacturers, different gas bottles, different torch angles, different pulse wave forms, different flow rates, different interpass temperatures, different cleaning techniques... none of which eliminated the porosity/inclusions.
Needless to say, I'm baffled as to what the cause of this may be. Does anyone have any suggestions or input?





RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
Are you using Lincoln's STT process and calling it pulsed transfer?
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
Stanweld: We have tried multiple wave forms and trim settings to no avail, though it wouldn't surprise me if it were somehow involved.
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
A few of your points we already addressed:
Electrically, we're ok. We are hard wired in with a bank of machines that are not in use while we are running this equipment, and it is a dedicated line to the test shop.
Wire was hermetically sealed and used fresh out of the package.
We are on the second regular and set of hoses, no issues there.
Running the 90/10, the parameters are as close to perfect as possible. Going in either direction on voltage (trim) or wire feed, performance begins to decline. It currently runs with almost no appreciable spatter whatsoever.
I too have faith in this process, and was really hoping to get a procedure qualified with it. Our application requires 100% PT, burn through is a concern, and they wanted a downhill procedure for production rates, so this process was ideal over a short arc procedure where lack of fusion would become a real concern given the abilities of our welders.
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
I would approach this by changing one variable at a time, in the following sequence:
(assuming there are no cleanliness issues)
1 - Different wire (a premium brand).
2 - Pulse parameters
3 - Travel speed, electrode angle, stickout
4 - Shield gas
Just a thought - could the heat of base metal be somehow implicated? Good luck - this is one more reason I got off the shop floor!
RE: GMAW-P on P4 Material
Even the "high quality" versions of these wires have the reduced silicon and manganese levels because they're designed primarily for wire fed GTAW applications. They have a 80S-B2 wire with a slightly higher silicon content and significantly higher manganese content on the way. That's really our last resort.
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
RE: GMAW-P on P4 Material
Thanks for the follow-up. Reviewing this thread, I assume that you increased the Mn content? What range are you having success with?
RE: GMAW-P on P4 Material