1. The proof stress of a material of 3 inches gage length is the highest stress it can withstand without a permanent set of above ___________ inch.
a) 0.0003
b) 0.21
c) 0.05
d) 0.004
Explanation: For a length of one inch, the permanent set of over 0.0001 inch withstanding is proof stress. For 3 inches length, it will be –
0.0001×3 = 0.0003 inches.
Hence, it is 0.0003 inches.
2. A materials proof stress is also referred to as ___________
a) elastic limit
b) yield limit
c) proportional limit
d) set method
Explanation: Proof stress of a material can also be called a proportional limit. The procedure to find the elastic limit and proof stress are similar, but the quantities are different. Yield limit can be found through tension testing, but it is not the same as proof stress.
3. The elongation of a material can be obtained through tension testing.
a) True
b) False
Explanation: A lot of basic properties of a material can be obtained through tension testing. It is an important test. One such property is the elongation of a material. It refers to the amount of increase in the length of a material.
4. Which of the following is not a hardness testing method?
a) Rockwell hardness
b) Brinell hardness
c) Set method hardness
d) Shore scleroscope hardness
Explanation: Hardness testing methods are processes to check the strength of the material. Rockwell hardness, Brinell hardness, Shore scleroscope hardness and Diamond pyramid hardness are typically used hardness tests. The set method is one of the methods used to determine the yield strength of a material.
5. It is vital that surfaces that have to be tested to determine the hardness of the material must be free of _____
a) ridges
b) evenness
c) smoothness
d) thickness
Explanation: In order to perform tests on the material, it must meet certain standards. It should have the required thickness to avoid bulging and must be free of ridges and scratches. It should be even and smooth.
6. It is impossible to find a relation between hardness and tensile strength.
a) True
b) False
Explanation: There is a relation between the hardness and tensile strength. The approximate value of the tensile strength of several materials can be found when the hardness of those materials is known.
7. For ____________ materials, there is no correspondence between tensile strength and hardness.
a) soft
b) hard materials
c) steel
d) carbon
Explanation: There is a relation between hardness and tensile strength for materials like carbon and low alloy steels. The tensile strength can be predicted using hardness values. But for comparatively soft materials like aluminium alloys, this is not applicable.
8. There is a necessity to find the hardness of a material without causing deformation in them.
a) True
b) False
Explanation: There is a necessity to find the hardness of a material as it can give an indication of the strength and several other properties of a material. At the same time, it is important to avoid damaging the material as that would be a loss. Especially for a manufactured material.
9. The Brinell testing method uses a steel ball of __________ diameter for testing purposes.
a) 26mm
b) 1mm
c) 10m
d) 10mm
Explanation: The Brinell test method involves pressing a hard ball made of steel, with a particular pressure onto the surface of the test specimen. The diameter of the steel ball being used is 10 mm.
10. In the Brinell testing method, the load should be pressed for a minimum of ____________
a) 1000 seconds
b) 60 seconds
c) 10 seconds
d) 3 seconds
Explanation: In the Brinell testing method, the test specimen is indented with a ball made of steel, with a diameter or 10 mm for a certain amount of time. The minimum time period is 10 seconds before the load is released.