I have a structure originally built from aluminum extrusion with channels using aluminum T-nuts and steel bolts. Over the years, the steel bolts have rusted, making them prone to stripping at the head and getting stuck in the nut. I'm going to replace a lot of the bolts to get rid of the rust. Worst case, I replace them with bare steel again, and accept that they will rust again over the next decade or two. I would prefer to avoid that. Can I grease the threads or cover the bolt head with plastic or wax or something like that? Is there a cheaper material than titanium that I could upgrade the bolts to? Are there other solutions I should be considering?
PS: The solution needs to be vibration-resistant.