TIG Welding 2024 Aluminum ("unweldable" alloy)

[jakeru]

You've heard about the "nonweldable" aluminum alloys, right? 2024 is on the short list. It is supposed to have big problems with hot cracking when welding. I've always wanted to see if I can weld a "nonweldable" alloy, and finally got around to trying it today. And you know what, I think I'd say I got a reasonably successful weld on just my first try.
Attachment 1872
Attachment 1873
Attachment 1871

No hot cracking tendencies were noted during welding, honestly. That is judging by my naked eye, and with bend testing. I did not do any die penetrant testing. I did use a pretty exotic, 4145 alloy filler rod I selected because, like 2024, it had a high copper content. (Unlike 2024, it had silicon it in, and lacked magnesium.) Since I haven't tried welding 2024 with any other rod yet, I woulnd't say its necessary or even best to get good results. Perhaps shearing off strips of 2024 might work just as well, if not better.

I have welded dissimilar aluminum alloys together that I struggled with hot cracking before I finally "cracked" the welding formula. I had no such problems with my 2024 welding attempt.

Judging from a couple bend tests I made, there is not a lot of ductility in the weld deposit, but there is at least *some* strength there. It did take a reasonable amount of force with the vice to get it to bend, and it did bend quite a bit in the parent metals before failing in the fusion zone.
Attachment 1870
Attachment 1869

For reference, here is what a 2024 parent metal (not welded) "bend until failure" test looks like (ductility test) This is also heat treated to T3 rating (2024-T3). The stuff is pretty strong, it flexes a good bit (being able to fully spring back) before it yields. It's seems like one of the less ductile aluminum alloys around though.
Attachment 1874

Maybe I did something right and stumbled across the magic 2024 welding formula on my first try, by accident? Or maybe welding 2024 is really just not as "unweldable" as the textbooks say it is?