Welding Tips and Tricks

I've tried googling this but didn't see anything so I figure I'd ask here, perhaps a dumb question, but AC is used on aluminum for the cleaning action of the positive half of the sinewave (or square or triangle etc), also good for welding dirty aluminum castings as Jody showed in a recent video. That made me wonder, is this cleaning action also in effect when welding on steels? Of course, would there be any point to it?

Yes. No.

AlO2 forms within nanoseconds after it is cleaned off of aluminum. No such layer forms on steel, at least not within that time-frame. But what ever oxides are there, would be wiped out to the sides, and if they are exposed to oxygen will form rust.

http://weldingweb.com/showthread.php?54 ... teel-on-AC

However, it is useful when brazing using Aluminum-Bronze on steel parts because, you guessed it, of the small aluminum content in aluminum-bronze filler. You just don't want to use a whole lot of EP% since it is not needed like when doing AC aluminum tig welding.

Thanks, it's mostly an academic question for me since I have a DC only machine but it's been something that's been running around in my head for a while. And I couldn't try it out because I was lacking the equipment.