What is effect of silicon on cast iron?

Q.  What is the effect of silicon on the structure of cast iron?

1. Blowholes are present in the castings
2. Increases fluidity
3. Influences the solidification of liquid alloys
4. Reacts with iron to form iron sulphide

- Published on 11 Sep 15

a. 1 and 2
b. 2 and 3
c. 3 and 4
d. All of the above

ANSWER: 2 and 3


  • Ramakanta Dash   -Posted on 28 Sep 17
    need some elaboration
  • Sravanthi   -Posted on 21 Nov 15
    - Silicon present in cast iron increases fluidity and influences solidification of liquid alloy.

    - When silicon content increases, austenite field and eutectoid carbon content decreases. This causes eutectoid transformation over a broad range.

    - According to stable iron-graphite system, silicon favors solidification if it is not counterbalanced by carbide promoting elements. Hence, carbon is precipitated as primary graphite during solidification in presence of silicon. Gray cast iron has low strength and ductility because of the notch effect observed at the end of these flakes. These flakes brake up the continuity of matrix.

    - As silicon content increases, it causes complete dissociation of cementite to graphite and ferrite. The ferritic gray cast iron formed has very low strength.

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