1. The load obtained in a tension test is 500N and the original cross sectional area is 250m2 what is the tensile strength of the material?
a) 5 m
b) 25 N/m2
c) 2 N/m2
d) 20 m
Explanation: Tensile strength = \(\frac{Maximum \,load \,obtained}{Original \,cross-sectional \,area}\)
= \(\frac{500}{250}\) = 2 N/m2.
2. The modulus of elasticity of a material can be described as ________
a) the product of stress and strain
b) the ratio of stress to strain
c) the product of yield point and strain
d) the ratio of change in length to original length
Explanation: The ratio of stress to strain is called the modulus of elasticity (within the elastic limit). The ratio of change in length to original length is called strain.
3. The ability of a material to resist permanent distortion or penetration is called as _______
a) hardness
b) yield point
c) malleability
d) elongation
Explanation: The ability of a material to resist permanent distortion or penetration is called hardness. Elongation is the increase in the length of a material. Malleability allows materials to bend without rupture.
4. What is the total permissible elongation for a gage length of 5.08cm?
a) 5080 cm
b) 0.00508 cm
c) 0.508 cm
d) 0.000508 cm
Explanation: The proof stress is the load a material can endure without permanent distortion of more than 0.0001cm per 1cm. So, if the gage length is 5.08cm, the total permissible elongation would be – 5.08×0.0001 = 0.000508cm.
5. What is the effect of heat treatment on a metal?
a) Improvement in availability
b) Improved physical properties
c) Decreased color
d) Decreased availability
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.
6. Quenching involves submerging a heated metal in a liquid to speed up its cooling process.
a) True
b) False
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.
7. Carburizing is ideally carried out on steels that have less than __________ carbon content.
a) 90%
b) 50%
c) 10%
d) 25%
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.
8. Annealing a metal ________ its internal strains.
a) doesn’t affect
b) removes
c) increases
d) doubles
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.
9. Casehardening refers to _________ the material, after which necessary heat treatment is done to it.
a) annealing
b) critical range
c) carburizing
d) hardening
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.
10. 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
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.