So, I'm rebuilding my old Sears floor jack from the early 1970's. It's the old metallic green color and has served me well. I need to replace the seals and such - not a big deal, should be kinda fun. However, I had to use the blue wrench to get one of the rusted nuts off. I have no idea what the grade of nut it was as it was not marked nor is the bolt it was on. I will post pics later to show where the nut was located.

The question is whether or not the nut was ever heat treated and whether or not I should re-harden the steel of the removed nut. I had to get it cherry red in order to get it off, so I'm pretty sure the nut has lost it's heat treatment.

I will most likely replace it, but this question came to mind so I thought to ask here since you guys do way more welding than I do.