[ithacaartist]

Several years ago, I made a pair of brass cafe' chairs, incorporated in a memorial sculpture by Robt. Bertoia (nephew, I think, of the more famous Harry Bertoia) on the Ithaca Commons. I copied all the design elements of a regular cafe' chair in 1/2" round brass stock--looped feet, twined members, etc. The weak point was the single strand on each side, which supported the chair backs. TIG welding had annealed the pieces at critical points to the extent that the soft material would have been an easy thing for potential vandals to break off, had I not reinforced these areas. This, because, as Jerry pointed out, there is no other way to re-harden brass than work hardening. Heating and allowing the metal to cool (relatively) slowly--annealing--softens most common metals. Not sure about titanium, as I have no experience with it. But as Jerry said, heating cupric alloys softens them whether or not they are quenched.

Back to the side plate lever, How 'bout obtaining a different side plate to try? Another option would be to change out the lever itself--a bit of a PITA, but way less involved than metallurgical shenanigans, and harmless to all components involved.