M.I.G. Welding Aluminum

[welder_guy]

Hi, I just tried to weld mig aluminum. i get this black soot around my weld. my argon gas flow is at 25 cfm.

[walker]

It ain't like steel. You need to clean the aluminum well, first with a SS wire brush tehn wipe it down with acetone. You still may get some sooting, but it should wipe off with a rag.

[jake]

gotta push too

pulling pulls you away from your shielding gas

[aametalmaster]

Here you go. How to reduce smut...Bob http://www.thefabricator.com/Aluminu...cle.cfm?ID=554

[BWS29128]

Back your flow down to between 15 and 20. Push, don't pull. As Bob's link states, 5356 is much more prone to smut. Are you used to doing any sort of "weave" with your MIG welding to get nice looking beads? If so, be forewarned that the INSTANT you back up or cross over a hot-but-cooling weld puddle in aluminum, you're going to get smut. I get quite a bit of smut when I'm welding C channel onto corrugated aluminum pipe because of the slight gap variations and because the ripples in the base metal cause me to move the nozzle to/away from the puddle as I follow the contours of the pipe. I use 5356 for added strength and additional corrosion resistance (from possible water runoff contaminants).