Question

Match the following:

• A. A-I, B-III, C-IV, D-II
• B. A-II, B-I, C-IV, D-III
• C. A-IV, B-I, C-II, D-III
• D. A-III, B-II, C-I, D-IV

Hint:

Pearlite = alternating layers of ferrite and cementite.

Answer 1

The Correct Option is B

Concept: The iron-carbon system contains important phases that define the mechanical behavior of steels. Each phase has a distinct crystal structure and carbon solubility.

Step 1: Identify Austenite.
Austenite:
• FCC phase of iron
• stable at high temperature
• high carbon solubility Thus: \[ A \rightarrow II \]

Step 2: Identify Ferrite.
Ferrite:
• BCC phase of iron
• soft and ductile
• low carbon solubility Thus: \[ B \rightarrow I \]

Step 3: Identify Cementite.
Cementite:
• iron carbide (Fe$_3$C)
• hard and brittle phase Thus: \[ C \rightarrow IV \]

Step 4: Identify Pearlite.
Pearlite:
• lamellar mixture of ferrite + cementite
• formed by eutectoid reaction Thus: \[ D \rightarrow III \] Final Answer: \[ \boxed{A-II,\; B-I,\; C-IV,\; D-III} \]