ME Metallurgy and Phase Diagrams 3

Question 1

Annealing of a cold-worked metal involves which sequence of microstructural changes?

Accepted Answer

Recovery → recrystallization → grain growth

Answer

Grain growth → recrystallization → recovery

Answer

Recrystallization → recovery → grain growth

Answer

Grain refinement → recovery → recrystallization

Question 2

Which type of heat treatment is used to reduce carbon content gradients in cast steel by diffusion at high temperature?

Accepted Answer

Homogenization (diffusion) annealing

Answer

Quenching

Answer

Tempering

Answer

Stress-relief annealing

Question 3

In an eutectic binary system, the eutectic point is where:

Accepted Answer

A liquid of fixed composition transforms into two distinct solid phases simultaneously

Answer

A single liquid transforms into a single solid on cooling

Answer

Two solids react to form one solid phase

Answer

A solid partially melts upon heating

Question 4

The solubility of carbon in alpha-ferrite at room temperature is approximately:

Accepted Answer

0.008 wt%

Answer

0.76 wt%

Answer

2.14 wt%

Answer

0.022 wt%

Question 5

Precipitation hardening (age hardening) strengthens an alloy by:

Accepted Answer

Precipitating fine, coherent second-phase particles that impede dislocation motion

Answer

Forming large carbide particles at grain boundaries

Answer

Increasing grain size to reduce grain boundary area

Answer

Dissolving all solute atoms in solid solution

Question 6

What is the primary purpose of case hardening (e.g., carburizing) in steel components?

Accepted Answer

To create a hard, wear-resistant surface layer while maintaining a tough core

Answer

To increase the carbon content uniformly throughout the part

Answer

To eliminate residual stresses from machining

Answer

To reduce the grain size across the entire cross-section