Question

Match the phenomena in Column I with the typical observations in Column II. Column I:
P. Dynamic strain aging
Q. Recrystallization
R. Bauschinger effect
S. Superplasticity
Column II:
1. Grain boundary sliding
2. Decrease in yield stress with a reversal of loading direction
3. Decrease in dislocation density
4. Serrations in stress–strain curve

• A. P–4, Q–1, R–2, S–3
• B. P–4, Q–3, R–2, S–1
• C. P–3, Q–4, R–2, S–1
• D. P–1, Q–4, R–2, S–3

Hint:

In "match the column" metallurgical questions, focus on key keywords: - DSA → Serrations, - Recrystallization → Dislocation reduction, - Bauschinger → Reverse loading effect, - Superplasticity → Grain boundary sliding.

Answer 1

The Correct Option is B

Step 1: Recall each phenomenon.
- Dynamic strain aging (DSA): Occurs due to interaction of dislocations with diffusing solute atoms. It produces \emph{serrations in the stress–strain curve} (P → 4).
- Recrystallization: Involves nucleation and growth of new grains, leading to a \emph{decrease in dislocation density} (Q → 3).
- Bauschinger effect: Phenomenon where material shows a \emph{decrease in yield stress upon reversal of loading direction} (R → 2).
- Superplasticity: Occurs at high temperature with fine grains, dominated by \emph{grain boundary sliding} (S → 1).
Step 2: Match with Column II.
- P → 4
- Q → 3
- R → 2
- S → 1
Step 3: Verify with options.
Option (B) gives P–4, Q–3, R–2, S–1, which is correct. \[ \boxed{\text{Correct Answer = (B)}} \]