This set of Testing of Materials Multiple Choice Questions & Answers (MCQs) focuses on “Rockwell Hardness Test”.
1. Which hardness test is most widely used in the US?
a) Brinell
b) Vickers
c) Shore
d) Rockwell
View Answer
Explanation: Most widely used hardness test is a Rockwell test in the US. It is because of the fast speed. It gives a small indentation.
2. Rockwell test utilizes ___________ a measure of hardness.
a) Load
b) Depth of indentation
c) Diameter of indentation
d) Time of loading
View Answer
Explanation: Rockwell test utilizes depth of indentation as a measure of hardness. It is done for the constant load. Time is specified.
3. A minor load of _________ is applied to seat the specimen in the Rockwell test.
a) 1 kg
b) 5 kg
c) 10 kg
d) 150 kg
View Answer
Explanation: Minor load is applied of 10 kg. It helps to seat the specimen. Major loads of 60, 100 and 150 kg are used.
4. What is a limitation of the Rockwell test?
a) Slow speed
b) Personal error
c) Bigger size of indentation
d) Different indenters
View Answer
Explanation: Indenters should be changed according to the hardness of the specimen. It takes less time to perform. It has freedom from personal error.
5. What minimizes the amount of surface preparation in Rockwell test?
a) Minor load
b) Indenter surface
c) Indenter geometry
d) Heat-treatment
View Answer
Explanation: Minor load of 10 kg is first applied. It helps to seat the specimen. It minimizes the amount of surface preparation because it can penetrate into the oxide or dust layer if any exists.
6. How much penetration is indicated by each division in dial in Rockwell test?
a) 0.2 mm
b) 0.02 mm
c) 0.002 mm
d) 0.0002 mm
View Answer
Explanation: The dial consists of 100 divisions in it. Each division represents 0.002 mm of penetration.
7. Hardened steel is tested on the C scale with ________ indenter and a _______ kg major load.
a) Diamond, 100
b) Diamond, 150
c) 1.6 mm steel ball, 100
d) 3.2 mm steel ball, 150
View Answer
Explanation: Hardened steel is a very hard material. So it is tested by the diamond indenter. On C scale, the load of 150 kg is applied.
8. Which scale is used to test softer materials?
a) A
b) B
c) C
d) D
View Answer
Explanation: B scale is used for testing softer materials. 1.6 mm steel ball is used for indentation. Major load of 100 kg is used.
9. What is the hardness of low brass?
a) HRB 40
b) HRB 55
c) HRC 55
d) HRC 60
View Answer
Explanation: Brass is tested on B scale. Its hardness is around HRB 55. Cartridge brass has the hardness of 93 HRB.
10. What is the hardness of martensite?
a) 40 HRB
b) 64 HRB
c) 40 HRC
d) 64 HRC
View Answer
Explanation: Hardness of martensite is measured on C scale. Its value is 64 HRC. Brale indenter is used for this purpose.
11. In A scale, steel ball indenter is used.
a) True
b) False
View Answer
Explanation: In A scale, diamond indenter is used. 60 kg major load is applied. It has a wide range of results.
12. Diamond indenter is known as ‘Brale indenter’.
a) True
b) False
View Answer
Explanation: Diamond indenter is 120° cone with a rounded point. It is used for harder materials. It is known as brale indenter.
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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