How does strain hardening affect a metal's properties?

Strain hardening, also known as work hardening, is a process where a metal becomes stronger and harder as it is deformed plastically at room temperature. When a metal undergoes plastic deformation, dislocation movements occur in its crystal structure. As these dislocations move, they multiply and interact with one another, creating a more complex dislocation structure that impedes further movement. This results in an increase in the material's strength and hardness.

The relationship between strain hardening and mechanical properties is crucial in applications where increased strength is needed without changing the overall mass of the material. In contrast, other options do not align with the fundamental principles of strain hardening. For example, strain hardening typically decreases ductility because the increased dislocation density makes it more difficult for the material to deform further without fracturing. Additionally, strain hardening does not inherently affect a metal's weight or thermal conductivity; instead, changes in these properties are influenced by different factors and processes.