This set of Aerospace Materials and Processes Multiple Choice Questions & Answers (MCQs) focuses on “Heat Treatment Terms”.
1. What is the effect of heat treatment on a metal?
a) Improvement in availability
b) Improved physical properties
c) Decreased color
d) Decreased availability
View Answer
Explanation: Heat treatment improves/changes the physical properties of a given metal. It is a set of processes involving several different methods like hardening, drawing, etc. Heat treatment does not affect the availability of the metal.
2. Quenching involves submerging a heated metal in a liquid to speed up its cooling process.
a) True
b) False
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Explanation: Quenching is the process of cooling a metal by submerging it in a liquid. It is a heat treatment process. The liquids used in this method are typically water or oil. It increases the strength of a material.
3. Carburizing is ideally carried out on steels that have less than __________ carbon content.
a) 90%
b) 50%
c) 10%
d) 25%
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Explanation: Carburizing is a process in which carbon is added to steel, by heating it in contact with a carbon-bearing material at a high temperature. Carburizing Is ideally carried out on steels that have less than 25% carbon content.
4. Annealing a metal ________ its internal strains.
a) doesn’t affect
b) removes
c) increases
d) doubles
View Answer
Explanation: Annealing a metal is heating it uniformly and then cooling it slowly. This alters the internal arrangement of atoms. Annealing is known to remove internal strains and decrease the hardness of the metal.
5. Casehardening refers to _________ the material, after which necessary heat treatment is done to it.
a) annealing
b) critical range
c) carburizing
d) hardening
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Explanation: In casehardening, the material has to first undergo carburizing. Then, the material is subjected to heat treatment. This is done to harden the surface of the material. Critical range is a range of temperatures at which the structure of a metal changes.
6. In the process of hardening of steel, the metal has to be heated to a temperature ______ the critical range.
a) below
b) half
c) above
d) around
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Explanation: In the process of hardening of steel, the metal has to be heated to a temperature above the critical range. Hardening increases the strength of the material. In order to alter the internal atomic structure of the steel to change its properties, heating it above the critical range is required.
7. Normalizing is a heat treatment carried out on all metals.
a) True
b) False
View Answer
Explanation: Normalizing is a heat treatment method of steel. It closely resembles annealing. But, compared to annealing it is faster and makes the material stronger. Also, annealing is done for several materials.
8. In the process of the hardening of aluminum alloys, what is the temperature above which it should be heated?
a) 1200°F
b) 600°F
c) 2400°F
d) 900°F
View Answer
Explanation: When a material is heated beyond its critical range, and subsequently undergoes the process of quenching it is called Hardening. Aluminum alloys are heated above temperatures of 900°F to be hardened.
9. Which heat treatment method is also called as “drawing”?
a) Tempering
b) Casehardening
c) Annealing
d) Normalizing
View Answer
Explanation: Tempering is also called drawing. Tempering, unlike other heat treatment methods, requires the metal to be reheated under the critical range. It is then cooled depending on the material and the requirement of its physical properties.
10. The critical range of steel is between ______
a) 1300°F and 1600°F
b) 2400°F and 2600°F
c) 900°F and 2800°F
d) 900°F and 2400°F
View Answer
Explanation: The critical range of steel is between 1300°F and 1600°F. Critical range of a material refers to the range between which internal change occurs in a metal. It is important in a lot of heat treatment methods.
Sanfoundry Global Education & Learning Series – Aerospace Materials and Processes.
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