Cast iron

pig iron, often along with substantial quantities of scrap iron, and taking various steps to remove undesirable contaminants such as silica, phosphorus and sulfur, which weaken the material. Carbon content is carefully reduced to the desired level, which may be anywhere from 2% to 3.5% depending on the application. (Carbon steel has less than 0.45% carbon.)

The salient feature of its manufacture is that the mix of about 3.5% carbon with iron makes an alloy that has a minimum melting point (ca 1420-1470 K), and therefore can be created at temperatures at least 300 K lower than the melting point of pure iron.

Cast iron is often used in the making of cookware. Cast-iron pots and pans are sturdy and conduct heat well, but require seasoning -- impregnation of the cooking surface with oil -- to prevent rusting and as a non-stick surface. Modern cast-iron pans are available pre-seasoned, but when cleaning one must take care not to scrub off this protective layer.