geezer - I came across numerous references in both books and online search to "unweldable" or "nonweldable" aluminum alloys. Here are a few:
http://www.esabna.com/us/en/educatio...num-alloys.cfm
http://www.lincolnelectric.ca/knowle...comistakes.asp
http://books.google.com/books?id=GcP...page&q&f=false

Even the weldability statement you quoted would appear to not allow TIG welding of the alloy (as that would be a "nonconsumable" electrode) welding. So I don't know? I sure have read about it being "nonweldable" over and over, but have thought it must not be quite that simple.

sportbike - Indeed it sounds like Stress Corrosion cracking could be a worry on welded 2024 if the part is subject for anything but light loading or is anything resembling a "critical weld", as I'm sure you encounter all the time at your work. I am guessing that testing stress corrosion cracking susceptibility, kind of like testing number of cycles until fatigue failure, is not very simple to do.

However, I don't think all applications of potential 2024 welding would necessarily be highly loaded or critical welds. For example, I spoke to one prospective customer who preferred using 2024 aluminum for his woodworking projects (I think making bandsaw tables and fences, etc) primarily because it "machined nicely." He said the other alloy he liked using because it "machined nicely" was 7075!

That is a cool trick about twisting two filler wires together to custom blend the composition. (And maybe this will be my excuse to pick up those safety wire twisters I've always wanted )