This looks like a fun ‘let’s post hard questions’ type thread - so here’s mine. This goes out to both the OP and any manufacturers out there and is related to the first question. I understand chemically what is different between 6061 and 7075 Aluminum. In helping answer question 2, 6061 Aluminum is general purpose Aluminum. It is not particularly high grade. 7075 aluminum is as far as I can tell a ‘higher grade’ Aluminum as it has been doped with Zinc:
A combination of good strength, corrosion resistance, and machinability makes this the most widely used aluminum. It has less strength than Alloys 2024 and 7075, but better corrosion resistance and weldability. It’s heat treatable and resists cracking due to stress. Commonly used for vehicle parts and pipe fittings. Nonmagnetic. Temperature range is -320° to +300° F.
Exceptionally strong but still lightweight, this aircraft alloy has better corrosion resistance than Alloy 2024 due to the addition of zinc. Originally developed for aircraft frames, it is also used for keys, gears, and other high-stress parts. Heat treatable. Nonmagnetic. Temperature range is -320° to +212° F.
The above is shamelessly stolen from my Aluminum supplier.
OK now to the question:
Why do manufacturers choose to use 7075 over other grades of Aluminum? Because of the zinc doping, this grade is always going to be difficult to anodize I would of thought. Realistically other grades of aluminum would probably be just as strong but much easier to ano, like 2024. It’s all so confusing…
I should add that these kinds of threads are great, and I really appreciate Supbreh doing this. But I also think that different people have different expertise so answering these questions is good for everyone to attempt. As long as Supbreh doesn’t mind. If so, I’ll delete some of the above as I may be treading on his toes… Sorry in advance, I didn’t mean to be funny
EDIT: I was asked to put up prices. I’m happy to do this on the basis that people remember this is just one supplier, and these are not typically bulk prices. With these factors in mind these are not a good enough data set to be conclusive about companies raw prices and so THESE SHOULD NOT BE USED TO DISPUTE THE PRICE OF A YOYO! They are a rough guide only.
6061 2" Diameter rod, of 1’ length (seems yoyo-ish in size) is ~$22
7075 2" Diameter rod, of 1’ length (seems yoyo-ish in size) is ~$62
2024 2" Diameter rod, of 1’ length (seems yoyo-ish in size) is ~$57, and is copper doped which should not be as difficult to ano and is still strong! There are so many grades to choose from…
Final note the same rod of titanium would be ~ $340!