welding on threaded aluminum

[ATOMonkey]

Sorry, but I disagree. I would rather see a complete solid weld, which becomes part of the parent material, then a plug which is welded only to one side or edge. Welding the hole solid, drilling and then tapping would be a much more robust repair.
Mark

Depends on the size of the hole and whether or not you want the part to be straight when you're done. That much weld puts a lot of heat into the part and has a large Heat Affected Zone (HAZ).

Doing a lot of welding also gives you more opportunity for an inclusion that will cause the piece to crack again later.

I've never had a part fail by doing a welded threaded plug. Even now, with it broke in two pieces, I'd still prefer to weld as little as possible. Of course, any kind of drilling and tapping would have to be done on a drill press at a minimum at this stage.