3 ms·

While you're correct about the oxide issue, there are welding processes which mitigate this. In particular, using alternating current instead of direct current

While you're correct about the oxide issue, there are welding processes which mitigate this. In particular, using alternating current instead of direct current causes a "cleaning" effect which knocks the oxide off of the weld area. Laser welding does a similar thing. If you're welding aluminum with DC stick, DC TIG, or just an oxy-acetylene torch you can get good results by grinding the weld area with a flapper disk and brushing immediately before welding with a stainless wire brush that has never touched anything but aluminum. For DC TIG and oxy-acetylene I've used flux coated welding rods as filler material with some luck. Also, you always need to keep oxygen away from weld, no matter what process or material you're welding. At welding temperatures metals will burn in the presence of oxygen. We do this by using shielding gasses, flux which burns and displaces the oxygen, using a slightly fuel-rich (or "reducing") flame, physically displacing all the oxygen (forge welding) etc.

dreamcompiler 2y ago
Correct about keeping oxygen away regardless of material. Aluminum is just much less forgiving than steel in this regard. I use the DC TIG process even for steel because it makes cleaner welds than sticks do. (TIG is also slower than stick, so it's less good for high-volume welding.) I've never tried flux-coated rods with aluminum because they seemed like a gimmick to me, but maybe I'll do an experiment.
- potato3732842 2y ago
  >I've never tried flux-coated rods with aluminum because they seemed like a gimmick to me, but maybe I'll do an experiment. They suck to use but they work. They're not really a production item. They're more for globbing something together in the field.
  - jcgrillo 2y ago
    > They suck to use but they work Yep, exactly. I welded a fitting onto a cast aluminum intake manifold using these things and an oxy-acetylene torch and it came out "good enough"

dreamcompiler 2y ago

Correct about keeping oxygen away regardless of material. Aluminum is just much less forgiving than steel in this regard. I use the DC TIG process even for steel because it makes cleaner welds than sticks do. (TIG is also slower than stick, so it's less good for high-volume welding.) I've never tried flux-coated rods with aluminum because they seemed like a gimmick to me, but maybe I'll do an experiment.

potato3732842 2y ago
>I've never tried flux-coated rods with aluminum because they seemed like a gimmick to me, but maybe I'll do an experiment. They suck to use but they work. They're not really a production item. They're more for globbing something together in the field.
- jcgrillo 2y ago
  > They suck to use but they work Yep, exactly. I welded a fitting onto a cast aluminum intake manifold using these things and an oxy-acetylene torch and it came out "good enough"