Wouldn't that depend on what hardy tooling you were making?  Bending tools---normalized. Cutting tools hardened and tempered if that is your preference.  Tools for ornamental surface application will last longer if hardened....

Ok that makes sense

The green bar is used as a  3 point hitch stabilizer (sway bar ). Attaches to the hitch pin  on one side of the implement , the other end to the side of the rear axle of the tractor

Ok thanks I didnt know thats what it was hmmm this will be fun