Can hardened steel work-harden?

[tornitore45]

I suppose work hardening is a mechanical/physical condition that has nothing to do with the condition af carbon diffusion and combination, since it happens on copper and aluminum.

[jpfalt]

Hardened steel can work harden in addition to being heat treated for hardness. Work hardening is the mechanical addition of dislocations in the metal crystals. The dislocations are places where the crystal structure is distorted so the planes of atoms in the metal crystals don't line up the way they normally would and the planes of atoms are no longer free to slide past each other. Hardening by heat treatment involves the location of metal impurities, such as carbon in iron structure so that the metal atoms are not free to slide in the crystal structure with the metal impurities acting like pegs in the structure or by distorting the crystal to form dislocations.

[tornitore45]

To be clear. Steel that is already hardened con get even harder by machining. Right?

I suppose the usual technique is to slow cutting speed, oil and frisky feed to make sure we are cutting and not rubbing.