I've got a lot of 6061 scrap 1/2 inch thick and larger. I make a fair amount of shop parts out of the scrap. The tool racks on three of my machines are the "good" side up of lots of 1/2 inch scrap as are the shelf brackets under them. Often for a small part for my own use I'll spend 20 minutes going through my scrap to pick a piece for the job. Anyway, I've got shelves, boxes, and atleast one cart full of failed job scraps.
I would use more of it if I felt comfortable welding anything that thick.
All of it is to thick for me to be able to weld easily. The thickest aluminum I have ever welded is 3/8 and it took me several tries. Lots of preheat made it happen. From what I have read it seems I can "learn to" weld that thicker stock with a small percentage of helium in the gas mix. I probably will not do enough of it to justify buying a helium bottle and setting up a mixing rig. I was thinking maybe to buy another bottle and get some premixed. My concern is that Helium is a very small molecule. I'm consider that if I have a bottle sitting there for a couple years between projects all the helium will ooze out leaving me with a bottle of nearly pure argon. Is this a real concern?