kylmämuokkausta

Kylmämuokkaus, also known as cold working, refers to the plastic deformation of metals at temperatures below their recrystallization point. This process significantly alters the mechanical properties of the material. The primary effect of kylmämuokkaus is an increase in strength and hardness, accompanied by a decrease in ductility. This phenomenon is known as work hardening or strain hardening.

The deformation occurs through the movement and multiplication of dislocations within the metal's crystal lattice. As the metal is deformed, these dislocations become entangled and impede each other's motion, requiring more stress to induce further plastic flow. This results in a higher yield strength and tensile strength for the material. However, the increased dislocation density also makes the material more prone to fracture under tensile stress, hence the reduction in ductility.

Common kylmämuokkaus processes include cold rolling, cold drawing, and cold forging. Cold rolling is used to produce thin sheets and foils with precise thickness and a smooth surface finish. Cold drawing is employed to create wires and bars with improved strength and dimensional accuracy. Cold forging is utilized to shape metal parts without significant material loss, often producing components with excellent mechanical properties.

While kylmämuokkaus enhances strength, the resulting material can become brittle and may require subsequent annealing to restore ductility if further forming operations are needed. The specific temperature range for kylmämuokkaus varies depending on the metal's composition and its recrystallization temperature.