Is this Metal safe to weld

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I purchased a 12' piece of angle at try recyclers today while I was getting rid of my scrap. There is zero rust and it is not very magnetic. I cut a couple 2" pieces off to set up my welder and prepped them with a flap disk. I wasn't shy with the disk hoping if there was a coating I would get passed it. I strike up my torch and it's as if I have no argon flow, stop to check and clean my tungsten strike up again same thing but it poofs out a little cloud powdering my table with white. I barely tack it together and the tack looks like stainless steel. I figured I would ask here before killing myself with some toxic gas. I've never welded galvanized or aluminized metal or anything coated so I'm not familiar with that bit. Here's a couple picture's if you need more just let me know of what. TIG, DCen, 100 amps full pedal for fusion tack, 2 lanthanated electrode, 7 cup at 14 scfh.




Reply:The white powder makes me think it's galvanized. Dunno.(One coating to definitely steer clear of is cadmium, which is often/usually yellow. I've heard the vapor from that will kill you. )   OTOH, the black "welds" make me think "no argon" or "wrong gas." Are you sure it's 100% argon?
Reply:99% chance that it is zinc coated,, probably was part of an old high voltage tower that was taken down, and scrapped.I have welded a LOT of zinc coated steel, it can give you "flu" symptoms,, I learned to use adequate ventilation in 1972, I ain't dead,,, yet,,,

Grind off ALL of the zinc, at least back 1/2", and try welding again. The zinc is probably hot dipped, not electroplated, it will be thick.
Reply:Aye, sounds like it's galvanized. The zinc layer will be what's causing your smoke and white powder, it's also pretty nasty to breathe in the fumes. Won't kill you but you can get metal fume fever from it which isn't a fun thing. There's no maximum thickness specified (usually) when they make hot dipped galvanized steel, only a minimum thickness. So it can be quite thick, there's also some zinc/iron mixing that occurs at the boundary of the coating and the base metal so you might have to grind deeper than you think to get rid of all the zinc. That mixed layer of zinc will still boil out when you weld over or near it. Depending on how much welding you need to do, you might consider picking up a welding respirator if you want maximum safety. It can be difficult to get rid of all the zinc.
Reply:The easiest test I can suggest is running a bead in the center of one of the cut ends, as sketched below. That is well away from the coating, so if it gives no problems, you know the surface had the "contamination" which I agree is probably zinc.

If you can stick weld too, you might try some 6010/6011 rods on the outer surface or edges, if only to see how it behaves and can (should) penetrate well enough to get the job done satisfactorily.