Machine Design Questions and Answers Part-2

1. Modulus of resilience is defined as
a) Strain energy per unit volume
b) Strain energy per unit area
c) Independent of Strain energy
d) None of the mentioned

Answer: a
Explanation: Modulus of resilience is strain energy per unit volume.

2. Which of the following are true for toughness
a) Ability of material to absorb energy before fracture
b) Measured by Izod & Charpy test
c) Decreases with the increase in temperature
d) All of the mentioned

Answer: d
Explanation: Toughness is measure of energy stored till fracture occurs. With rise of temperature, molecular bonds weakens and fracture occurs at a lesser load, hence area under stress strain curve decreases

3. Malleability increases with temperature while ductility decreases with temperature.
a) true
b) false

Answer: a
Explanation: Malleability is the deformation under compressive load and hence with rise in temperature, the deformation increases and hence malleability increases.

4. Hardness is
a) Surface property
b) Resistance to abrasion
c) Depends upon resistance to plastic deformation of the material
d) All of the mentioned

Answer: d
Explanation: Hardness is a surface property which is the resistance of material to surface indentation. It depends upon resistance to plastic deformation.

5. Ductile cast iron is
a) Also called nodular cast iron
b) Also called spheroidal graphite cast iron
c) Carbon is present in form of spherical nodules
d) All of the mentioned

Answer: d
Explanation: Ductile cast iron, also called as nodular cast iron or spheroidal cast iron consists of carbon in the form of spherical nodules in a ductile matrix.

6. Grey Cast iron is formed when
a) Carbon content in the alloy exceeds the amount that can be dissolved
b) Carbon content in the alloy is less than the amount that can be dissolved
c) Carbon content in the alloy is equal to the amount that can be dissolved in the alloy
d) None of the mentioned

Answer: a
Explanation: Grey Cast iron is formed only when carbon is present exceeds the solving capacity.

7. White cast iron is formed when
a) Graphite flakes are formed
b) Most of the carbon content in the alloy forms iron carbide
c) No iron carbide is formed
d) None of the mentioned

Answer: b
Explanation: White cast iron is formed when most carbon in alloy forms iron carbide and there are no graphite flakes.

8. The term high alloy steels is used for alloy steels containing more than ___ of alloying elements.
a) 10%
b) 20%
c) 50%
d) 70%

Answer: a
Explanation: The term high alloy steels is used when alloying elements exceed 10%.Low and medium alloy steels are those when this figure is less than 10%.

9. Which of the following are true about low carbon steels?
a) Carbon content < 0.3%
b) Also called as mild steel
c) Are soft and ductile
d) All of the mentioned

Answer: d
Explanation: Low carbon steels contain carbon <0.3%. Because of low carbon, it is soft and ductile.

10. Which of the following are true for high carbon steels?
a) Carbon content=0.4%
b) Respond readily to heat treatments
c) Have much ductility as compared to low and medium carbon steels
d) Easy to weld

Answer: b
Explanation: High carbon steel have carbon % >0.5 and hence have less ductility. They are difficult to weld.