Question

To produce malleable cast iron, the silicon content must be:

• A. 1%
• B. 2.5%
• C. 5%
• D. 10%

Hint:

For malleable cast iron, silicon content must be kept low (around 1%) to suppress graphite formation and allow proper heat treatment of white iron.

Answer 1

The Correct Option is A

Malleable cast iron is produced by heat-treating white cast iron under controlled conditions.
A key factor in producing malleable cast iron is maintaining a relatively low silicon content — typically around 1%.
Silicon promotes graphitization, which is not desirable in the white cast iron that serves as the precursor to malleable iron. Therefore, for white iron to be converted into malleable cast iron, the silicon content must be limited to prevent the formation of graphite during solidification.
Higher percentages of silicon (such as 2.5% and above) are suitable for gray cast iron, not malleable types.