1. Which of the following property will be more in fine grained structure?
a) Ductility
b) Corrosion resistance
c) Creep resistance
d) Hardness
Explanation: Finer the grain size (lower the grain size), more is the number of grain boundaries, thus more is the yield strength, thus more is the ductility. This is the reason why we can easily draw a fine-grained structure into wires.
2. Which of the following property will be more in coarse grain structure?
a) Ductility
b) Corrosion resistance
c) Hardness
d) Toughness
Explanation: Grain boundaries are susceptible to corrosion. Coarse grain structure has less grain boundaries, thus has greater corrosion resistance
3. Which of the following penetrating liquid is used in a liquid penetration test?
a) Water
b) Chlorine based solvent
c) Petroleum based carrier fluid
d) Fluorine based solvent
Explanation: In liquid penetration test, either petroleum-or-water based carrier fluids are used as solvents or cleaners according to the type of penetrant used. Petroleum based carrier fluid is used as penetrating liquid in liquid penetration test along with fluorescent red colour dye for visible light.
4. Which of the following non destructive testing is used to detect change in composition of any material?
a) Liquid penetration test
b) Ultrasonic test
c) Eddy current test
d) Radiography
Explanation: Radiography enables us to detect the change in composition. X-rays or γ-rays are used in radiography technique.
5. The melting point of iron (in oC) is?
a) 768
b) 1535
c) 1410
d) 910
Explanation: Melting point of iron in degree centigrade is 1535oC.
6. Iron-Carbon phase diagram is a __________
a) Unary phase diagram
b) Binary phase diagram
c) Tertiary phase diagram
d) Ternary phase diagram
Explanation: Binary phase diagrams are based on two component systems. Here, the two components may be mixed in an infinite number of different proportions, which indicates that composition also becomes a variable, along with pressure and temperature. Iron-carbon phase diagram, Pb-Sn diagram are the best examples of this category.
7. The temperature (in oC) of peritectic reaction in iron-carbon phase diagram is?
a) 1539
b) 1493
c) 910
d) 1175
Explanation: The invariant peritectic reaction (while cooling) in Fe-C phase diagram is given by:
L (0.53%C) + δ-ferrite (BCC, 0.09%C) \(_{\overrightarrow{1493^o C}}\) γ (FCC, 0.17%C)
8. The temperature (in oC) of eutectic reaction in iron-carbon phase diagram is?
a) 1539
b) 1493
c) 910
d) 1150
Explanation: The invariant eutectic reaction (while cooling) in Fe-C phase diagram is given by:
L (4.3%C) \(_{\overrightarrow{1150^o C}}\) γ (FCC, 2.11%C) + Cementite (Orthorhombic, 6.67%C)
9. The temperature (in oC) of eutectoid reaction in iron-carbon phase diagram is?
a) 1120
b) 725
c) 910
d) 820
Explanation: The invariant peritectoid reaction (while cooling) in Fe-C phase diagram is given by
γ (FCC, 0.77%C) \(_{\overrightarrow{725^o C}}\)Ferrite (BCC, 0.02%C)+ Cementite (Orthorhombic, 6.67%C).
10. The percentage of carbon at eutectic point in Fe-C phase diagram is?
a) 2.1
b) 4.3
c) 0.83
d) 0.02
Explanation: The lowest melting alloy, the Fe-4.3% C alloy is called eutectic cast iron. This is a single-phase liquid (100%) of 4.3% carbon at the eutectic temeprature 1150oC.