Engineering and fabrication

What engineering properties are likely to decline during the cold working of a metal?

What engineering properties are likely to decline during the cold working of a metal?

Public Comments

1. it decreases the ductility of the metal

   it also decreases the ageing time of the metal



2. As the metal is formed into the desired shape or form, the metal becomes more brittle and less malleable. Over time, the metal could develop a crack and possibly cause damage to the structure it was used for. This is called fatigue cracking.


3. *Cold rolling is a metal working process in which metal is deformed by passing it through rollers at a temperature below its recrystallization temperature.

   *Cold rolling increases the yield strength and hardness of a metal by introducing defects into the metal's crystal structure.

   *These defects prevent further slip and can reduce the grain size of the metal, resulting in Hall-Petch hardening.

   *Cold rolling is a method of cold working a metal. When a metal is cold worked, microscopic defects are nucleated throughout the deformed area. These defects can be either point defects (a vacancy on the crystal lattice) or a line defect (an extra half plane of atoms jammed in a crystal). *As defects accumulate through deformation, it becomes increasingly more difficult for slip, or the movement of defects, to occur. This results in a hardening of the metal.

   *If enough grains split apart, a grain may split into two or more grains in order to minimize the strain energy of the system. When large grains split into smaller grains, the alloy hardens as a result of the Hall-Petch relationship. If cold work is continued, the hardened metal may fracture.

   *During cold rolling, metal absorbs a great deal of energy, some of this energy is used to nucleate and move defects (and subsequently deform the metal). The remainder of the energy is released as heat.

   *While cold rolling increases the hardness and strength of a metal, it also results in a large decrease in ductility. Thus metals strengthened by cold rolling are more sensitive to the presence of cracks and are prone to brittle fracture.