coldhardened

Coldhardened is an adjective used to describe a material whose hardness has been increased through cold working, i.e., plastic deformation at or near room temperature, rather than by heating. In metals, this process introduces dislocations and strain hardening, raising yield and tensile strength and hardness, while reducing ductility. The extent of hardening depends on the amount and type of deformation, the material’s composition, and any subsequent thermal history. Common cold-working methods include drawing, rolling, bending, punching, or extruding at ambient temperatures.

Cold hardening is often used to achieve higher wear resistance and strength in components such as steel wires, sheet metals, and aluminum profiles. It is frequently followed by annealing or stress-relief treatments to relieve residual stresses and restore some ductility, if required. In some cases, parts are designed to operate in the range where the increased strength is beneficial without unacceptable brittleness.

Limitations include reduced toughness and potential cracking if work is too severe or not properly annealed, and the hardness is not uniformly distributed if the deformation is nonuniform. The process also increases residual stresses that can cause distortion or warping. The material’s performance can change over time if subjected to further work or service conditions that promote recovery or recrystallization.

Coldhardened contrasts with heat treatment, where hardness is primarily increased by diffusion or phase transformations at elevated temperatures. Some alloys are also subject to work hardening during service, which can alter properties over time.