# Mechanical Metallurgy Questions and Answers – Fracture Types in Metal – 1

This set of Mechanical Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Fracture Types in Metal – 1”.

1. The Ionic crystal generally fracture in __________
a) ductile manner
b) brittle manner
c) creep manner
d) fatigue manner

Explanation: The ionic solid has high directional bonding. So the crack propagation is always in the specific direction and brittle.

2. The tendency of brittle fracture increase on ___________
a) decreasing temperature and strain rate
b) increasing temperature and strain rate
c) decreasing temperature and increasing strain rate
d) increasing temperature and decreasing strain rate

Explanation: Brittle fracture increases with a decrease in temperature because the ductility of material reduces. Also increasing strain rate increases the brittle fracture tendency of material.

3. The brittle fracture is considered much more severe than ductile fracture.
a) True
b) False

Explanation: The brittle fracture generally occurs without any gross deformation or visible warning. So this type of fracture can be risky.

4. The following diagram shows the structure of material after fracture into two parts. Which of the following represent completely ductile material?
a)

b)

c)

d)

Explanation: The completely ductile material will fracture by elongation. The elongation will reduce the thickness of the sample from braking point and pure ductile which will reduce to a point in the end.

5. The brittle fracture is not observed in ___________
a) BCC
b) FCC
c) HCP
d) DC

Explanation: The brittle fracture is generally observed in BCC, HCP but not in FCC until unless there is grain boundary embrittlement.
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6. The “cup and cone” structure is associated with ___________
a) ductile fracture
b) brittle fracture
c) creep fracture
d) fatigue fracture

Explanation: In the cup and cone structure, the material neck is down and then fractures by shearing along 45o plane. This produces the familiar cup and cone shape. So it is generally signifying the ductile fracture.

7. The appearance of surface of brittle fracture will be ___________
a) grey and fibrous
b) bright and granular
c) dull and granular
d) riverlike pattern

Explanation: The brittle fracture propagates along the grain boundary of material on the plane perpendicular to the applied load with any plastic deformation. So the appearance is generally granularly showing the different grains and shiny because of no deformation.

8. The appearance of surface of ductile fracture will be ___________
a) grey and fibrous
b) bright and granular
c) dull and granular
d) riverlike pattern

Explanation: The ductile fracture occurs by gross deformation before fracture, which gives it a fibrous structure; the surface is not flat, causing its dull appearance.

9. Which of the following is correct?
a) Trangranular crack: crack propagates through the grain
b) Intergranular crack: crack propagates through the grain
c) Trangranular crack: crack propagates along the grain boundary
d) Intergranular crack: crack propagates along the surface of the sample

Explanation: Transgranular cracks means the crack propagates through the grain, while intergranular means the crack propagates along the grain boundaries.

10. The following curve represents the cohesive force between atoms with respect to interatomic distance. The distance X represents ________

a) equilibrium force between atoms
b) the minimum force between atoms
c) the cohesive strength of the material
d) theoretical Strength of material

Explanation: The point X represents the maximum attractive force which the atoms will transmit when they are separated from each other from their equilibrium position. Beyond this point, the attractive force between atoms will reduce.

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