First, please forgive the "noobness" of my questions. I am very new to weld process controls, and am currently awaiting my copies of Ed Craig's materials.
For those unfamiliar, I am working with stainless piping and 308L Si .035" wire on OTC robots. We are running tests in an effort to convert from He tri-mix over to an Ar/CO2 2-3%. These are images of one of our test pieces:
HE on right, Ar on left.
I am at a loss for what WS or Welding Speed actually is, but we changed from 20 to 34 ipm. I want to think this is travel speed. There is a debate here that it might be feed rate...but I thought feed rate was adjusted through amperage. Any insight?
Closer shot of the He weld
Closer shot of the Ar weld
The He weld looks tighter and smoother at the edges than the Ar weld. Can you help explain this? I have my own thoughts, but am not ready to confidently speculate.
Also, both welds have a similar color, which what looks like flaking or scaling. The color is decent, but I am not crazy about this property. It happens during solidification. It seems to me like the outer shell of the weld solidifies first, and because of contact with the atmosphere there is an oxidation layer that forms. As the molten weld cools it shrinks and this change in surface area breaks the oxidation layer, revealing a shiny weld substrate. Am I off base? How can I minimize this property without resorting to a passivization process?
Lastly, what impact would using O2 have on our processes, versus CO2? The bulk system here uses O2, and it would be far easier to calibrate that to a 2% mix with Ar rather than switching to CO2.
Marcus