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Aluminum dc tig welding is a lot different than ac tig

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  • Aluminum dc tig welding is a lot different than ac tig

    I decided to try to dc tig weld on the surface of 1/4" aluminum plate. I used 100% argon and around 250 amps with thoriated tungsten. it was a lot different than ac tig with pure tungsten,but at the same amperage. i brushed off the weld, and showed it to someone. they said, "Did i stick rod it." It is a lot cleaner than stickrod,but with the same shiny weld. The bead appearance was shaped more like stickrod than ac tig. it looks strange when attempting it,however it could help if i have to try welding thick aluminum plate 1" thick again. i prrobably would do atleast my first pass in dc tig to insure good penatration. tthen cover it with the more traditional ac tig bead on top!

  • #2
    Originally posted by jamesmg View Post
    I decided to try to dc tig weld on the surface of 1/4" aluminum plate. I used 100% argon and around 250 amps with thoriated tungsten. it was a lot different than ac tig with pure tungsten,but at the same amperage. i brushed off the weld, and showed it to someone. they said, "Did i stick rod it." It is a lot cleaner than stickrod,but with the same shiny weld. The bead appearance was shaped more like stickrod than ac tig. it looks strange when attempting it,however it could help if i have to try welding thick aluminum plate 1" thick again. i prrobably would do atleast my first pass in dc tig to insure good penatration. tthen cover it with the more traditional ac tig bead on top!
    The only DC TIG on Aluminum that I've seen was done with pure helium. When I worked in aerospace years ago, the welders who worked on rocket engine frames, turbo pumps and fuel and oxidizer ducts were using transformer machines with DC and helium. The welds were absolutely perfect with stacks of dimes and clean as a whistle. All welds were X-rayed, numbered and stamped by the inspector when completed.

    That was long before square wave or inverter machines came along.

    If you could get some helium, you could use a lot lower amperage for a given thickness.
    Miller Syncrowave 200
    Milermatic 252
    Lincoln AC/DC "Tombstone"

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