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+--- Thread: How Welding old aluminum tread plate?? (/Thread-How-Welding-old-aluminum-tread-plate)
How Welding old aluminum tread plate?? - aluhm - 02-28-2018
Someone asked to weld up a stand using some old aluminum tread plate. I needed to machine some fittings from new 6061-T6 bar and structural tubing, then weld them to the tread plate.
The old aluminum tread plate was oxidized on both sides, but the smooth side looked worse to me. There was no obvious pitting on either side.
One of the machined pieces attached to the smooth side of the plate. I cleaned the plate with a flap disc followed with stainless steel wire brushing of the plate and fitting. The weld was no problem at all, and the result looked great.
The other pieces were prepped in exactly the same way, but the weld to the tread (bumpy) side of the plate was nearly impossible. I used the same machine, same settings, and same filler rod. Every time I started a puddle, it would film over with black crud, and it was downhill from there. Repeated cleaning didn't improve things. I tried different settings to no avail, and even went to a larger electrode so I could use higher current. All the changes were tried on scraps of new aluminum, and I could get a nice puddle and bead on it.
I eventually got a barely acceptable weld on the work, but I was really disappointed with the way it looked. Fortunately, the fellow was happy with it.
Any idea what the problem(s) could have been? Is something done to the tread side of the plate that would interfere with welding? Both sides looked equally shiny and clean after the prep.
RE: How Welding old aluminum tread plate?? - KamorkasOa - 06-19-2018
I used to do repair work on livestock trailers...after shoveling out the you-know-what. Treadplate is embossed...or, the diamonds are rolled into the surface. The compressed aluminum itself can be weird enough and old aluminum welds worse than fresh aluminum (also worked on new livestock trailers where the material was new).
It really sounds like you are dealing with a coated or flash plated material. The tread side gets a coat of something and will be a bitch to weld unless that plating/coating is completely removed. Fasteners are quite often the best way to assemble aluminum and welding often reserved for more of a seal than any kind of strutural thing.
RE: How Welding old aluminum tread plate?? - ircasodle - 06-19-2018
what you describe is pretty much what i found doing cast aluminum
grind and prep squeeky clean only to have the weld turn up like crap with black and all
that.
preheat does a pretty good job getting the oils and other crap cooked out, but i found that
if i was to go over the weld area with the tig first without filler it was amazing how much crap would boil out and blacken the part.
i would do the first pass that way, then go back and regrind, brush and clean
reheat and go at it the final time with filler rod... nice clean weld then.
that was on cast, which is somewhat porous, maybe the treadplate gets some crap imbedded in it somehow?