This set of Mechanical Behaviour Multiple Choice Questions & Answers (MCQs) focuses on “Brittle Fracture”.
1. What is cleavage plane for FCC materials?
a) {1 1 1}
b) {1 1 0}
c) {1 2 3}
d) {1 0 1}
View Answer
Explanation: The cleavage plane is the plane on which crack propagation or cleavage occurs during the fracture of the crystal.
| Crystal structure | Cleavage plane |
|---|---|
| Face-centred materials (FCC) | {1 1 1} |
| Body-centered structure (BCC) | {1 1 0} |
| Hexagonal close packing (HCP) | {0 0 0 1} |
2. What is the cleavage plane for HCP materials?
a) {1 2 3 0}
b) {1 0 0 0}
c) {0 0 0 1}
d) {1 0 0}
View Answer
Explanation: Basal planes are {0 0 0 1} in HCP metals. These planes act as cleavage planes. These fail in brittle manner in these planes.
3. Which material fails by brittle fracture?
a) White cast iron
b) Steel
c) Aluminum
d) Copper
View Answer
Explanation: White cast iron consists of cementite in excess. It causes a brittle fracture. Fe3C is a brittle material because of strong bonding.
4. Which of the following materials don’t give brittle fracture?
a) White cast iron
b) Grey cast iron
c) Aluminum
d) Ceramics
View Answer
Explanation: Aluminum shows a ductile fracture. White and grey cast iron and ceramics show brittle fracture. Grey cast irons have flake-like graphite which increases stress at their tips.
5. When does brittle fracture is noticed?
a) On overloading
b) On sudden loading
c) Uniaxial loading
d) Compressing
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Explanation: Brittle fracture occurs on sudden loading. This dynamic loading leads to an abrupt failure. It can be dangerous.
6. What is characteristic of brittle fracture?
a) Prior warning
b) High speed
c) Necking
d) Ductile rupture
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Explanation: Brittle fracture occurs at high speed reaching to 1200 m/s in steel. It doesn’t show prior warning or necking. Ductile rupture occurs in ductile materials.
7. Fracture always occurs above yield stress.
a) True
b) False
View Answer
Explanation: Brittle fracture occurs at a lower stress level than yield stress. It causes fracture without plastic deformation. This phenomenon is catastrophic.
8. In ____ fracture, crack is unstable and propagates rapidly.
a) Ductile
b) Brittle
c) Shear
d) Tensile
View Answer
Explanation: In brittle fracture, crack is said to be unstable. It propagates at high speed. Its propagation doesn’t require an increase in stress level.
9. Brittle fracture is a break in a brittle piece of metal that failed because stress exceeds _____
a) Cohesion
b) Adhesion
c) Yield stress
d) Tensile stress
View Answer
Explanation: When stress exceeds the cohesion, brittle fracture occurs. It occurs below yield stress. It occurs at a lower level of stress.
10. Which of the followings is not a type of fracture in brittle materials?
a) Bright granular
b) Flat type
c) Neck
d) Chevron patterns
View Answer
Explanation: Brittle fracture appears bright granular. It looks the flat type. Chevron patterns may be present.
11. The crack may be __________ and ____________ depending on strength of grain boundaries.
a) Brittle, ductile
b) Trans granular, intergranular
c) Shear, cleavage
d) Fibrous, granular
View Answer
Explanation: Depending on strength of grain boundaries, fractures are of two types. These are trans granular and intergranular. While on the basis of appearance, fibrous and granular fracture.
12. In intergranular fracture, crack travels along grain boundaries.
a) True
b) False
View Answer
Explanation: Crack travels along grain boundaries in intergranular fracture. It occurs when the grain boundary is weak and brittle. Cracks don’t pass through the actual grains.
Sanfoundry Global Education & Learning Series – Mechanical Behaviour & Testing of Materials.
To practice all areas of Mechanical Behaviour & Testing of Materials, here is complete set of 1000+ Multiple Choice Questions and Answers.
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