USA made Cannondales are aluminum. That's what made them famous. Not the first company to use aluminum but the first to go big. They used modern large scale manufacturing techniques like laser mitering. Frames were welded, then bolted to jigs for heat treatment to relieve the stresses in the metal caused by welding. They had 2 factories, the first in Connecticut and another in Pennsylvannia. They foolishly expanded in to stunt motor cycles with it's very small market potential and went bankrupt in 2003. Later bought by Pacific, the main supplier to walmart. Pacific gets all their bikes from Asia, including Cannondales. They still sponsor a Tour de France race team. Most recently Pacific was boughy by a Dutch conglomerate. since about 2009, the more expensive Cannondales have carbon fibre frames.
With aluminum, if it gets bent, any attempts to bend it back will usually snap it right off. There are a variety of aluminum alloys. the two most common alloys used in the bike industry are 6061 and 7001. There are also pre-heat treated aluminum alloys used in glued and screwed bike frames. Due to the manufacturing methods, none are repairable back to stock specs. The old joke on damaged Cannondales is to get your 5 cent deposit back. When I took welding courses, I learned a lot about the egos of some welders who claim they could weld anything. All of them are quite clueless about how bike frames are made. Any welded back together frame should not be trusted and won't hold for very long. It would need to be heat treated again which surely won't happen. Our local bike coop has a pretty strict policy of scraping out any damaged or re-welded frames due to liability concerns. Most regular bike shops won't touch damaged frames. I've consulted with highly skilled custom frame builders about repairing a variety of frames and the estimates every time have been more than buying a whole new bike.
The older Cannondale aluminum frames are actually quite sturdy and durable. From the photo above I don't see any obvious damage.
