Engineering Metallurgy - Mechanical Engineering (MCQ) questions and answers for Q. 10168

Q.  In mottled cast iron, slow cooling rate is used to obtain ______
- Published on 11 Sep 15

a. white cast iron
b. gray cast iron
c. Both a. and b.
d. None of the above

ANSWER: gray cast iron
 

    Discussion

  • Sravanthi   -Posted on 21 Nov 15
    - In mottled cast iron, gray cast iron is obtained by slow cooling rate. In mottled cast iron, part of carbon is in the form of graphite in free state and part of it is in the form of carbides.

    - White cast iron can be obtained by fast cooling rate. Thus by varying the cooling rate different cast irons are obtained from mottled cast iron.

    - The names gray and white cast iron are given depending upon their interior appearance.

    - Mottled cast iron has good surface hardness and wear resistance. This cast iron is used in mill rolls, brake shoes, flour milling shafts, etc

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