Welding a crack is not the most ideal. As stated its been fatigued already and the crack is merely the area that chose to tear. However, if you add material, like a plate of aluminum over the crack and fully weld that in place without damaging the frame, you may very well have a good repair. Also as stated heat treating should be considered. I would talk to a custom fabrication shop rather than a bicycle shop for this. They will understand the materials and determine whether or not a strong repair can be made, it does not have to do with bicycles at this point.

mm yeah i like the original.. dunno about this tho..