Originally Posted by Duragrouch

Umm... I don't like to be an a-hole and throw education out there... but all steels are susceptible to work hardening. It's why low-carbon and no-alloy steel can make piano wire that is well over 300ksi strength, about 10X the steel's original strength, purely due to the work hardening of drawing the metal multiple times through a die. It's why hard swords and knives were possible before alloy steels. Now, that derailleur hanger may not have gotten work hardened at the bend if not too severe. But all steels, in fact most metals, will work harden. Brass work hardens, which is why, firearm cartridge cases, after shooting and reloading several times (which involves "resizing" the case in a die), need to have the case necks annealed, so they maintain sufficient ductility for a proper bullet crimp.

High-alloy steels, such as "stainless" steels, same thing, but additional issue: All you have to do is get them heated above the hardening temperature, and they will harden simply by air cooling, they don't need to be quenched, as the alloys increase the "hardenability". If you've ever drilled through a piece of stainless, didn't keep it cool, saw just the tiniest spark at the drilling point, and suddenly it's hard as glass, you need to go find a tungsten carbide-tipped or boron steel drill to finish the job.