Question

Silicon in cast iron 
1. makes the iron soft and easily machinable 
2. increases hardness and brittleness
3. makes the iron white and hard
4. aids fusibility and fluidity

Answer 1

Correct Answer - Option 1 : makes the iron soft and easily machinable 

Concept:

• Addition of the Silicon in cast iron promotes the formation of free graphite which makes the iron soft and machinable.
• Addition of Silicon in cast iron shifts the Fe-C curve on the left side.
• Due to this, the graphitization will appear at much lower % of carbon.
• The left side of Fe-C having less % of carbon means the hardness of the material is less.