Definition - What does Cold Working mean?
Cold working is the process of strengthening metals through plastic deformation. This is made possible through the dislocation movements that are produced within a material's crystal structure.
This is a technique commonly used in non-brittle metals that have remarkably elevated melting points. A number of polymers can also be strengthened using this method. However, cold-worked areas in metal are more prone to corrosion due to heightened dislocation concentration.
Cold working is also known as work hardening.
Corrosionpedia explains Cold Working
Cold working involves the alteration of the size and shape of metals by means of plastic deformation. This process includes:
It is performed under the point of re-crystallization, typically at room temperature. The tensile strength and hardness are enhanced depending on the extent of cold working. As the strength increases, the values of impact and ductility weaken.
Although work hardening may be beneficial as it improves surface finish, strength properties, dimension control and reduced directional properties, it must be noted that it also has various disadvantages. Hence, industries, such as those that utilize metal parts, like boilers, should be aware that the process of cold working may result in:
- Reduced ductility
- Higher force needed for deformation
- Strain hardening
- Unwanted residual stress
A simple example to represent these cons is a nail that corrodes in parts where it has been bent or hammered, such as the body or head. Thus, industries that work on metals and utilize the cold-working process should apply the appropriate corrosion protection.