Fundamentals of Engineering Materials Science 2

Question 1

On the iron-carbon phase diagram, the eutectoid composition is approximately:

Accepted Answer

0.76 wt% C

Answer

0.022 wt% C

Answer

2.14 wt% C

Answer

4.30 wt% C

Question 2

Martensite in steel is formed by:

Accepted Answer

Rapid quenching of austenite

Answer

Slow furnace cooling of austenite

Answer

Isothermal holding just below the eutectoid temperature

Answer

Prolonged annealing in the two-phase region

Question 3

Which heat treatment reduces brittleness of quenched (martensitic) steel by heating below the eutectoid temperature?

Accepted Answer

Tempering

Answer

Normalizing

Answer

Full annealing

Answer

Case hardening

Question 4

The lever rule in a two-phase region of a phase diagram is used to determine:

Accepted Answer

The relative weight fractions of each phase present

Answer

The liquidus temperature at a given composition

Answer

The diffusivity of solute atoms in the matrix

Answer

The equilibrium crystal structure of each phase

Question 5

Precipitation hardening (age hardening) increases strength by:

Accepted Answer

Generating fine precipitates throughout the matrix that obstruct dislocation motion

Answer

Forming a complete solid solution that distorts the lattice uniformly

Answer

Increasing grain size to reduce total grain boundary area

Answer

Dissolving interstitial impurities into the crystal lattice

Question 6

The glass transition temperature (Tg) of a polymer is best described as the temperature:

Accepted Answer

Below which the polymer becomes glassy, stiff, and brittle

Answer

At which the polymer melts and flows as a viscous liquid

Answer

At which the polymer undergoes chemical decomposition

Answer

At which crystallization from the melt begins

Question 7

Charpy and Izod impact tests primarily measure a material's:

Accepted Answer

Impact toughness (energy absorbed before fracture)

Answer

Surface hardness

Answer

Ultimate tensile strength

Answer

Fatigue endurance limit