Question

The primary result of grain growth in a material is

• A. Improved conductivity
• B. Increased ductility
• C. Decreased strength
• D. Enhanced corrosion resistance

Hint:

Grain Growth Effects. Occurs after recrystallization at high temperatures. Average grain size increases. Reduces total grain boundary area. Primary mechanical effect: Decreases yield strength and hardness (softening).

Answer 1

The Correct Option is C

Grain growth is the process occurring during annealing (at temperatures above recrystallization) where larger grains grow at the expense of smaller ones, reducing the total grain boundary area.
Grain boundaries generally act as barriers to dislocation movement, contributing to the strength of polycrystalline materials (Hall-Petch effect).
As grains grow larger, the density of grain boundaries decreases.
This reduction in grain boundary area makes it easier for dislocations to move, leading to a decrease in the material's yield strength and hardness.
While grain growth might slightly affect conductivity or corrosion resistance in complex ways, the most significant and primary mechanical consequence is the decrease in strength and hardness.
Ductility might slightly increase or decrease depending on the extent of growth and initial state.