Why is gray cast iron annealed?

Q.  Why is gray cast iron annealed?
- Published on 11 Sep 15

a. Graphitize carbide
b. Decrease ductility
c. Both a. and b.
d. None of the above

ANSWER: Graphitize carbide


  • Sravanthi   -Posted on 21 Nov 15
    - Residual stresses are developed in gray cast iron due to cooling and contraction.

    - The stresses developed can be removed by by soaking it at 650° C but is avoided because grain growth is serious above 600 °C.

    - Hence, gray cast iron is annealed to graphitize carbide. This treatment homogenises casting, softens, increases machinability and ductility of gray cast iron.

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