2A2 Power Engineering Chapter 4 Metallurgy UPDATED ACTUAL
Questions and CORRECT Answers
Question: What is extractive metallurgy?
Correct Answer: The study of the extraction and purification of metals from their ores, conducted in
several steps.
Question: What are the three methods of refining metal in extractive metallurgy?
Correct Answer: 1. Pyrometallurgy: melting the ore in a furnace. 2. Hydrometallurgy: dissolving the metal
from the ore and recovering it as a powder. 3. Electrometallurgy: using electricity to dissolve the metal from
the ore and plate it out of solution.
Question: What does mechanical metallurgy study?
Correct Answer: The techniques and mechanical forces that shape and create finished forms of metal,
including the effects of stress, time, and temperature.
Question: What is physical metallurgy?
Correct Answer: The study of the structure of metals and how their properties are related to their
structures.
Question: How do metals typically occur in nature?
Correct Answer: Metals occur in ores as chemical compounds such as sulphides or oxides.
Question: What is corrosion in the context of metals?
Correct Answer: The process by which metallic materials react chemically with the environment and
revert to compound forms.
Question: What are some non-ferrous materials used in power plant construction?
Correct Answer: Copper-based alloys for condenser tubing, copper for alternator winding, tin-based alloys
for bearings, and aluminum for bus bars.
Question: What happens to metals at their melting point?
Correct Answer: Cohesive bonds break, allowing atoms to travel freely in the liquid state, with heat
energy absorbed without a temperature increase until all metal is liquid.
Question: What is the latent heat of fusion?
Correct Answer: The heat energy absorbed during the transition from solid to liquid at the melting point.
Question: What are unit cells in metals?
Correct Answer: Fixed configurations of individual atoms that form a rigid atomic structure when metal
solidifies.
Question: What are the three basic structures of unit cells in metals?
Correct Answer: 1. Face-centered cubic (FCC) 2. Body-centered cubic (BCC) 3. Close packed hexagonal
(CPH)
Question: What is the high-atom packed density structure found in lead?
, Correct Answer: Face-Centered Cubic (FCC) structure, which is easier to pull compared to
Body-Centered Cubic (BCC) structure.
Question: What is the characteristic of the BCC structure in iron?
Correct Answer: It has a low-atom packed density, requiring a large force for atoms to move as they must
jump over atoms below them.
Question: Define polymorphism in metals.
Correct Answer: Polymorphism is the ability of a metal to change to a different unit cell structure
depending on its temperature.
Question: What is allotropy of iron?
Correct Answer: The change in atomic cell structure of iron dependent on temperature, affecting its
melting point, hardness, metal solubility, and alloying chemistry.
Question: What is the significance of the iron-carbon equilibrium diagram?
Correct Answer: It controls the phase change of iron in the presence of carbon and other alloying materials
to produce high-strength steel.
Question: What is the maximum carbon content in carbon steel?
Correct Answer: 2% or less carbon.
Question: What are the three grades of carbon steel based on carbon content?
Correct Answer: Low Carbon Steel (max 0.3%), Medium Carbon Steel (0.30-0.60%), High Carbon Steel
(0.60-1.00%).
Question: What is cementite?
Correct Answer: Cementite is the common name for iron-carbon in the form of molecular iron carbide
(Fe3C).
Question: What is the structure of austenite?
Correct Answer: Austenite is the FCC structure of iron, also known as gamma iron, containing dissolved
carbon atoms up to 2%.
Question: What is the eutectic reaction point in the iron-carbon system?
Correct Answer: It occurs at 4.0% carbon and 1130°C, where the liquid alloy changes directly into solid
austenite and cementite.
Question: What is ferrite in the context of iron?
Correct Answer: Ferrite is the BCC structure of iron with a maximum carbon content of 0.025% at 723°C.
Question: What does the lower critical change line indicate?
Correct Answer: It indicates the temperature at which an iron alloy of any carbon composition returns to a
body-centered cubic unit cell structure, which is 723°C.
Question: What is pearlite?
Correct Answer: Pearlite consists of a layered structure of ferrite and cementite.
Question: How does carbon content affect the properties of steel?
Questions and CORRECT Answers
Question: What is extractive metallurgy?
Correct Answer: The study of the extraction and purification of metals from their ores, conducted in
several steps.
Question: What are the three methods of refining metal in extractive metallurgy?
Correct Answer: 1. Pyrometallurgy: melting the ore in a furnace. 2. Hydrometallurgy: dissolving the metal
from the ore and recovering it as a powder. 3. Electrometallurgy: using electricity to dissolve the metal from
the ore and plate it out of solution.
Question: What does mechanical metallurgy study?
Correct Answer: The techniques and mechanical forces that shape and create finished forms of metal,
including the effects of stress, time, and temperature.
Question: What is physical metallurgy?
Correct Answer: The study of the structure of metals and how their properties are related to their
structures.
Question: How do metals typically occur in nature?
Correct Answer: Metals occur in ores as chemical compounds such as sulphides or oxides.
Question: What is corrosion in the context of metals?
Correct Answer: The process by which metallic materials react chemically with the environment and
revert to compound forms.
Question: What are some non-ferrous materials used in power plant construction?
Correct Answer: Copper-based alloys for condenser tubing, copper for alternator winding, tin-based alloys
for bearings, and aluminum for bus bars.
Question: What happens to metals at their melting point?
Correct Answer: Cohesive bonds break, allowing atoms to travel freely in the liquid state, with heat
energy absorbed without a temperature increase until all metal is liquid.
Question: What is the latent heat of fusion?
Correct Answer: The heat energy absorbed during the transition from solid to liquid at the melting point.
Question: What are unit cells in metals?
Correct Answer: Fixed configurations of individual atoms that form a rigid atomic structure when metal
solidifies.
Question: What are the three basic structures of unit cells in metals?
Correct Answer: 1. Face-centered cubic (FCC) 2. Body-centered cubic (BCC) 3. Close packed hexagonal
(CPH)
Question: What is the high-atom packed density structure found in lead?
, Correct Answer: Face-Centered Cubic (FCC) structure, which is easier to pull compared to
Body-Centered Cubic (BCC) structure.
Question: What is the characteristic of the BCC structure in iron?
Correct Answer: It has a low-atom packed density, requiring a large force for atoms to move as they must
jump over atoms below them.
Question: Define polymorphism in metals.
Correct Answer: Polymorphism is the ability of a metal to change to a different unit cell structure
depending on its temperature.
Question: What is allotropy of iron?
Correct Answer: The change in atomic cell structure of iron dependent on temperature, affecting its
melting point, hardness, metal solubility, and alloying chemistry.
Question: What is the significance of the iron-carbon equilibrium diagram?
Correct Answer: It controls the phase change of iron in the presence of carbon and other alloying materials
to produce high-strength steel.
Question: What is the maximum carbon content in carbon steel?
Correct Answer: 2% or less carbon.
Question: What are the three grades of carbon steel based on carbon content?
Correct Answer: Low Carbon Steel (max 0.3%), Medium Carbon Steel (0.30-0.60%), High Carbon Steel
(0.60-1.00%).
Question: What is cementite?
Correct Answer: Cementite is the common name for iron-carbon in the form of molecular iron carbide
(Fe3C).
Question: What is the structure of austenite?
Correct Answer: Austenite is the FCC structure of iron, also known as gamma iron, containing dissolved
carbon atoms up to 2%.
Question: What is the eutectic reaction point in the iron-carbon system?
Correct Answer: It occurs at 4.0% carbon and 1130°C, where the liquid alloy changes directly into solid
austenite and cementite.
Question: What is ferrite in the context of iron?
Correct Answer: Ferrite is the BCC structure of iron with a maximum carbon content of 0.025% at 723°C.
Question: What does the lower critical change line indicate?
Correct Answer: It indicates the temperature at which an iron alloy of any carbon composition returns to a
body-centered cubic unit cell structure, which is 723°C.
Question: What is pearlite?
Correct Answer: Pearlite consists of a layered structure of ferrite and cementite.
Question: How does carbon content affect the properties of steel?
