Question

Cast iron with high-silicon content is a

• A. White iron
• B. Grey iron
• C. Malleable iron
• D. Pig iron

Hint:

High silicon promotes graphite formation, leading to grey cast iron.

Answer 1

The Correct Option is B

Step 1: Role of silicon in cast iron.
Silicon is a graphitizing element in cast iron. Higher silicon content promotes the formation of free graphite rather than cementite.
Step 2: Characteristics of grey cast iron.
Grey iron contains graphite flakes in its microstructure, which are formed due to the presence of higher silicon content. This gives the fracture surface a grey appearance.
Step 3: Eliminating other options.
(A) White iron: Forms when silicon content is low and carbon exists as cementite.
(C) Malleable iron: Produced by heat treatment of white iron.
(D) Pig iron: A raw material, not a final cast iron type.
Step 4: Conclusion.
Therefore, cast iron with high silicon content is grey iron.