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

During annealing, recovery occurs first (reducing residual stresses), followed by recrystallization (forming new strain-free grains), then grain growth.

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

Homogenization annealing holds the alloy at a high temperature for an extended time to allow diffusion to eliminate compositional segregation from solidification.

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

At the eutectic point, a liquid of fixed composition undergoes a simultaneous transformation into two distinct solid phases at a constant temperature.

Question 4

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

Accepted Answer

0.008 wt%

Answer

Alpha-ferrite (BCC iron) can dissolve only about 0.008 wt% C at room temperature because its interstitial sites are too small for much carbon.

Question 5

Precipitation hardening (age hardening) strengthens an alloy by:

Accepted Answer

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

Answer

Precipitation hardening produces fine, coherent precipitates dispersed throughout the matrix that act as obstacles to dislocation movement, increasing strength.

ME - Materials Engineer Practice Test

ME - Materials Engineer Practice Test

ME Metallurgy and Phase Diagrams 3