Gray iron, or grey cast iron, is a type of cast iron that has a graphite microstructure. It is named after the gray color of the fracture it forms. The gray cast iron is used for custom grey iron castings where the stiffness of the component is more important than its tensile strength, such as internal combustion engine cylinder blocks, pump housings, valve bodies, electrical boxes, counter weights and decorative castings. Grey cast iron's high thermal conductivity and specific head capacity are often exploited to make cast iron cookware and disc brake rotors. Grey cast iron (also called grey cast iron) is a group of cast iron including several kinds of grade according to different designation of diverse standards. Gray cast iron is a kind of iron-carbon alloy and it gets its name "grey" from the fact that their cutting sections looks grey. The metallographic structure of gray cast iron is mainly composed of flake graphite, metal matrix and grain boundary eutectic. During the grey iron, the Carbon is in the flake graphite. As one of the widely used casting metals, cast gray iron has many advangates in costs, castability and machinablity.