What is cast iron primarily composed of?

Cast iron is primarily composed of iron along with a significant amount of carbon, typically ranging from 2% to 4%, and silicon, which usually makes up about 1% to 3% of the composition. This specific combination of materials gives cast iron its characteristic properties, such as excellent castability, wear resistance, and machinability.

The carbon in cast iron primarily exists in the form of graphite, which contributes to its ability to dampen vibrations and improve its thermal conductivity, making it an ideal material for various applications like engine blocks and pipes. Silicon also plays a critical role in promoting the formation of graphite, enhancing the cast iron’s mechanical properties.

In contrast, other combinations listed do not reflect the typical composition of cast iron. For example, aluminum and copper are not primary constituents of cast iron and would not contribute to the distinct characteristics associated with it.