I'm probablly going to sound stupid here, but i have question.

So the setting of my story involves something that isn't quite post-apocalyptic, but i wanted it to give a similar vibe. I was considering making the backstory for this world setting involve a dwindling supply of raw metals in the nation. Something that would make only the biggest businesses to afford it resulting in lots of citizens need to reuse and re-purpose scrap unless they can afford high end stuff. Another government superpower would have all the metal resources they need for military robots and their county's citizens and that would help drive a plot i had.

After i had my morning cup of coffee, i realized that sounded really stupid, since metals can be melted down and reused, so im looking for some alternatives that would have a futuristic America desperate to make machines that would stand against another country's larger than life mechanized army. I really don't know anything about government and economics so a push in the right direction would be VERY appreciated.

The problem with melting down scrap metal is that, yeah, you could purify it pretty easily, but you have no idea what grade of metal it is. You could need some 1075 spring steel, but you don't even know if that scrap on the ground is titanium, aluminum, steel, or just some random other metal. That makes creating stuff quite difficult, especially if you need blades. Not just sword blades, but things like razor blades, lawnmower blades, kitchen knives, etc.

Having a large business with the capability of simply KNOWING what they're working with gives them a competitive advantage, and would make scrap sellers who are mechanically capable all the more valuable.

If still you want a sort of "oh no we've run out of this particular resource scenario" (which is what it seemed like you were doing with the metal), here's an alternative to metal that I think (seeing also as this is a futuristic America lol) would fit better. Oil. The US depends so much on oil. If you were to write an America that never converted to other resources and is then left to face with the oil shortage, that could definitely leave your world in a similar scenario.