Question

Specify the sequence correctly

• A. Stress relief, grain growth, recrystallisation
• B. Grain growth, recrystallisation, stress relief
• C. Grain growth, stress relief, recrystallisation
• D. Stress relief, recrystallisation, grain growth

Hint:

Recrystallisation occurs at a temperature of \(0.3 - 0.5 T_m\) (melting temperature), while grain growth happens at higher temperatures.

Answer 1

The Correct Option is D

When a metal undergoes cold working or plastic deformation, it experiences changes in internal structure. The correct sequence of heat treatment processes that restore the material properties is as follows: Step 1: Stress Relief - The first step is stress relief annealing, where the material is heated below the recrystallization temperature. - This process removes residual stresses caused by cold working without significant changes in microstructure.


Step 2: Recrystallisation - When the metal is further heated above the recrystallisation temperature, new strain-free grains begin to form. - This eliminates the effects of work hardening and restores ductility.


Step 3: Grain Growth - If the material is heated further, grain growth occurs, where small grains merge to form larger ones. - This process increases grain size and reduces mechanical strength but improves toughness.


Step 4: Conclusion Since the correct sequence of processes is Stress relief → Recrystallisation → Grain growth, the correct answer is option (D).