[ithacaartist]

I just looked it up, and work hardening occurs with the molecular rearrangement of the lattice in the material. These 'Dislocations" add up until the point of crystallization. I included mechanical pounding (intermittent compressive force) in the list of ways work hardening is induced, the others being torsion and tension, as you mentioned, all of which forces cause molecular dislocations. Work hardening is done on other materials such as copper and aluminum, in their transformations into sheets, wire, etc, which are not able to be hardened by heat treat, as steel is.