In Engineering Plant the Cast Iron is obtained by re-melting Pig Iron with Coke and Limestone in Cupola Furnace.
It is primarily an alloy of Iron and Carbon. So, The Carbon content varies from 1.7 to 4.5 %.
It also contains small amounts of Silicon, Manganese, Phosphorus, and Sulfur.
The Carbon in it is present either of following forms,
01) Free Carbon or Graphite.
02) Combined Carbon.
Hence we cannot use this material in those Parts of Machines which are subjected to Shocks.
This is due to its Property of Brittleness.
So, Below is the description of Cast Iron
The Compressive Strength of this material is much greater than the Tensile Strength.
Hence it has good Casting characteristics, high Compressive Strength, Wear Resistance, Excellent Machinability and Low in Cost.
These Properties made, a valuable Material for Engineering Purpose.
Following are the various types of cast iron, used in Engineering Field
Effect of Impurities
As you know from above, that it contains small percentages of Silicon, Manganese, Phosphorus, and Sulfur.
These may be treated as Impurities in the C. I.
So, the effect of these Impurities on the as Iron is as follows.
It makes C.I. Hard and Brittle. Hence it should be kept well below 0.1% for Foundry Purpose.
It makes C.I. White and Hard. Because of this, it is often kept below 0.75%.
Also, it helps to exert a controlling influence over the harmful effects of Sulfur.
Hence has become an engineering material with a wide range of applications and is used in pipes, machines and automotive industry parts.
Also, used for cylinder heads (declining usage), cylinder blocks and gearbox cases (declining usage).
Besides this information, you are suggested to read something more from below engineering books
To get the more details about the topic, I further recommended reading