When I took about the rear hub of my old Kent Folder, I noticed that the axle was bent a little. It is a non-quick release hub, so the axle is a solid threaded rod - something like 10mm diameter. I want to replace it. I know steel is not just steel - some is stronger. I could go buy some threaded steel stock and cut to length, but I'm not sure if axles are made of something special. Any insights?

I was a bit surprised to see it bent - I would expect a 10 mm steel axle to be pretty strong. I bought the bike used and maybe a previous owner was really heavy.

Robert