Materials Science Multiple Choice Questions & Answers (MCQs) on “Fundamentals of Failure”.
1. Improper heat treatment can cause mechanical failure.
a) True
b) False
Answer: a
Clarification: There are many causes of mechanical failure such as improper heat treatment, misuse, design errors, improper material and many other causes.
2. Buckling in a column occurs in the material due to which of the following forces?
a) Compressive
b) Tensile
c) Shear
d) It doesn’t occur due to a force
Answer: a
Clarification: Buckling in columns is a type of mechanical failure which occurs in materials due to the application of compressive load.
3. Which of the following is not a factor affecting fracture?
a) Stress concentration
b) Temperature
c) Pressure
d) Speed of loading
Answer: c
Clarification: Pressure isn’t a factor which affects fracture. Fracture of a material id affected by factors like stress concentration, thermal shock, temperature and speed of loading.
4. Which of the following is false?
a) Notch is a sudden change in section of a material
b) Stress concentration is produced due to notches
c) Notches change the stress applied to the body
d) Smaller the tip of the notch, less the increase in stress
Answer: d
Clarification: A notch is a sudden change in section of a material and stress concentrations are produced due to it. The smaller the tip of a notch the larger is the increase in stress.
5. Is the speed of loading is increased then:
a) Chances of fracture increases
b) Chances of fracture decreases
c) Chances of fracture remain the same
d) Elasticity of the body increases
Answer: a
Clarification: When the speed of loading is increased, the stress increases suddenly on the same section of the material which can lead to early failure in the form of fracture.
6. At what temperature is steel ductile?
a) -10 °C
b) -5 °C
c) -3 °C
d) 4 °C
Answer: d
Clarification: Steel acts as a ductile material at a temperature above 0 °C while it acts as a brittle material below 0 °C. Therefore at -10 °C, -5 °C, -3 °C steel will be brittle and not ductile.
7. Which of the following decreases transition temperature in steel?
a) Carbon
b) Nitrogen
c) Phosphorous
d) Manganese
Answer: d
Clarification: Alloying elements like manganese and nickel decrease the transition temperature of steel while alloying elements like carbon, nitrogen and phosphorous increases the transition temperature.
8. When hot water is poured into the cold glass, the glass may crack.
a) True
b) False
Answer: a
Clarification: The above statement is true. When hot water is poured in a cold glass, the glass may get cracked due to thermal shock due to the sudden change in temperature of the glass.
9. What is the relation between fracture toughness and thickness?
a) Fracture toughness decreases with increase in thickness
b) Fracture toughness increases with increase in thickness
c) Fracture toughness does not depend on the thickness
d) Fracture toughness increase linearly with an increase in thickness
Answer: a
Clarification: As the thickness increases the fracture toughness of the material decreases. It follows a curve and is not a linear graph.
10. Which of the following elements reduce fracture toughness in steel?
a) Phosphorous
b) Manganese
c) Iron
d) Aluminium
Answer: a
Clarification: There are some alloying elements which reduce fracture toughness in alloys. For an alloy like steel, phosphorous and sulphur decrease the fracture toughness in steel.