What is the main consequence of cold working on the mechanical properties of metals?

The main consequence of cold working on the mechanical properties of metals is that it increases strength but decreases ductility.

- Cold working, also known as work hardening, involves deforming a metal plastically at temperatures below its recrystallization point.
- This process introduces a high density of dislocations within the metal's crystal structure.
- The interaction and entanglement of these dislocations hinder the movement of other dislocations, thereby increasing the metal's strength and hardness.
- However, as the metal becomes stronger, it also becomes less capable of deforming plastically, which leads to a reduction in ductility.
- This trade-off between strength and ductility is a critical consideration in metal forming and mechanical design.

Important points:
- Cold working increases the dislocation density in metals.
- Movement of dislocations is hindered, resulting in higher strength and hardness.
- Ductility decreases because the metal becomes less able to deform plastically.
- The process does not significantly improve corrosion resistance or electrical conductivity.
- Tensile strength generally increases rather than decreases during cold working.

Reference: Callister, W.D., Jr., Materials Science and Engineering: An Introduction, 9th Edition, Chapter 6: Mechanical Properties of Metals and Alloys / Page 234-236