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Aluminum welding questions, and one SS/TI question

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  • Gaslight
    Thanks for all those great points.

    I saw this article where a guy was saying that the OH was specified for aircraft aluminum, only because Acetalyne was reserved for the shipyards during the war.

    Any particular brand for aluminum electrodes?

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  • Paul Seaman
    GTA all the aluminum I've ever seen welded was done AC with high frequency,
    I would like to see some DC for comparison.


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  • eric75
    According to "Getting an A in Aluminum" by Kent Caveny, aluminum can be welded with OA.
    Using his method, a water soluble flux is brushed on and heated gently with the flame to evaporate the water. The flux cleans off the oxide layer just as the AC would. After the weld is complete, you must be careful to wash off all the corrosive and toxic flux to prevent damage to the part, to your tools, and to your health.
    He does seem to hint that welding with OA requires a lot of skill and a properly set-up torch.

    The book is preparation for welding body panels for hot rods, so the procedures discussed are only for .060" thick 3003H14 aluminum.

    I think the biggest problem with OA welding aluminum is that you just can't get enough heat into a small enough flame, so GTA/SPEC may still be correct that you can't weld thicker aluminum with OA.

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    1 You cant OA weld aluminum. However, you can OH weld aluminum. (oxy-Hydrogen) You can DC weld Aluminum with the GTA process, in either a straight or reverse polarity. In straight polartiy, it is important to weld at a much higher arc voltage, in order to pierce the oxide. This can be done through different gases or the use of a plasma column.

    2 Yes they work, in emergencies

    3 Many fluxes are avaliable for tig welding. None work as well as back purging. One company makes a flux that will triple you penetration without growing your HAZ.

    Anything is possible in welding, you just need to open your mind.

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  • Aluminum welding questions, and one SS/TI question

    I'm familiar with the general GTAW theory on aluminum.

    I do have two questions:

    1) With OA welding on aluminum, the flame/gas creates a zone of protection similar to what you get with the gas when GTAW welding aluminum. It would seem impossible to ensure that what with spot welds, and interruptions in the work, that the weld had never cooled out of the gas (no post flow), or you never cut into a section that had already been welded, and would have some oxide on it. Why is it fine to weld this way, but you can only GTAW aluminum with an AC current (usually pretty sophisticated AC)? How does OA de-oxidize the join as you work along? Why is OA considered good, but DC GTAW on Al doesn't work.

    2) Someone once mentioned they used to sell Al stick electrodes. What is the story on that? How well or badly did they work?

    3) When forge-welding steels, including SS, you can get real good results. The means of keeping your surfaces clean relative to weld quality is to use a reducing flame, and a flux. When DC GTAWing on SS or maybe even TI, the recommended strategy is to backpurge the weld area, or even in some cases weld in a sealed cabinet. Is it ever possible to use a flux to protect the joint? Let's say you have a well fitted joint, and it at the borderline of needing purging, are there any fluxes that could be used to preserve the joint integrity while doing GTAW.

    I'm just curious about this stuff, I'm not trying to rewrite the book on nuclear sub welding. Sometimes there are fixes out there that might help redneck engineering. In some cases they may have been standard practice until they were superceded with more modern methods.