Question

Which of the following is the effect of recrystallization on the properties of a material?

• A. Increases hardness and brittleness
• B. Reduces ductility and increases stiffness
• C. Reduces strength and increases ductility
• D. Increases electrical conductivity and reduces thermal conductivity

Hint:

Recrystallization Effects. Occurs after cold work upon heating. Forms new, strain-free grains. Reverses effects of strain hardening: Decreases strength/hardness, Increases ductility/toughness.

Answer 1

The Correct Option is C

Recrystallization is an annealing process that occurs when a cold-worked (strain-hardened) metal is heated above its recrystallization temperature.
During cold working, the material becomes stronger and harder but less ductile due to an increase in dislocation density.
Recrystallization involves the formation and growth of new, strain-free grains, effectively eliminating most of the dislocations introduced during cold working.
The primary effects of recrystallization are: - Significant decrease in tensile strength and hardness (returning towards the pre-cold-worked state).
- Significant increase in ductility and toughness.
- Slight changes in electrical/thermal conductivity (often an increase due to reduced scattering sites).
- Stiffness (Modulus of Elasticity) is largely unaffected by recrystallization.
Option (3) correctly describes the main mechanical property changes: reduced strength and increased ductility.