My Passport has done an excellent job of welding 1/8" Al brackets. I'm quite happy with this one. The welds look great, but are covered with a uniform pitch black soot which I think is pure carbon. Is this normal? I'm using Argon, dcep, flow 25-30 cfh. The heat is awesome. .030 at full speed, volts at 6? is actually a hair too hot for 1/8". I wonder how much hotter it would be with helium.
Sounds like you are welding backhand. Always MIG weld aluminum forehand , or pushing the torch. Your welds will be cleaner.
Don't try pure helium, but a Argon/Helium mix can give really nice results with Aluminum MIG.
The soot is actually burnt aluminum oxide.
What do you mean by burnt aluminum oxide, when something is burnt usually it means heat and oxygen were added to it so wouldn't burnt aluminum be aluminum oxide? Also I always thought that aluminum oxide was clear as in anodising, why does this stuff turn black? Is it actually aluminum oxide with more oxygen added?
There is more in aluminum than just aluminum. Magnesium, zinc, copper and silicon are all major alloying ingredients and can change the appearance of the "soot" around the weld.
Oh and BTW Grey grinding wheels, and rubies are also aluminum oxide.
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