The loss of ductility and gain in hardness resulting from strain aging. An increase in hardness and strength caused by plastic deformation at temperatures below the recrystallization range.

With strain hardening, there is an increase of strength by straining of the microstructure. It occurs, when hot-formed steel products are re-drawn, re-rolled, etc. Before a further cold forming, such products have to be (soft) annealed, unless strain hardening was the target of the cold forming.

The increase in hardness and strength of a ductile metal as it is plastically deformed below its recrystallization temperature.