Cast iron is created by smelting iron ore, charcoal, and limestone under intense air pressure. It is refined to create wrought iron, cast iron, or steel. It was first used in China around the 11th century BC and the name comes from its manufacturing process. Cast iron is used to create pots and pans and is an intermediate step in creating steel, which has surpassed traditional forms of iron as a building material.
Cast iron is a metallic material that results when iron ore, charcoal from coal, and limestone are smelted together under intense air pressure. When the combined material cools, it forms a high carbon product known as pig iron. The cooled material is rarely used on its own, as the large amount of carbon makes the material brittle and unstable. Usually, this type of iron is further refined through further smelting and blending processes to create wrought iron, cast iron, or steel.
It is unclear when cast iron first became known in human technology, but some experts believe it was first used in China around the 11th century BC Chinese blacksmiths are believed to have built cannons and weapons in this shape of iron, also using it for decorative arts such as statues and figurines. While the use of iron was also common across Europe from the same period, the refining techniques used to produce pig iron and the resulting alloys may not have spread across Europe until many centuries later.
The name of this material derives from a first manufacturing technique. As hot molten ore was poured out of the blast furnace, it flowed into a long tray, called a runner, with several smaller inlets off a main branch. The runner and its small offshoots were said to resemble a sow and piglets, hence the augmentation of the common name, cast iron.
Many iron products start with cast iron. Wrought iron was once one of the most formidable building materials in the world, used as the frame for structures such as the Eiffel Tower. Today, real wrought iron is rarely available, due to the superior capabilities and strength of steel. To create wrought iron from cast iron, the alloy is remelted and combined with metal oxides that strip away some of the carbon, making the resulting alloy more usable and less brittle.
Cast iron is another type of alloy that can be refined from the starting material. Cast iron is stronger and less brittle than the initial material, thanks to a process that removes carbon, sulfur and other elements while adding desirable characteristics from molten scrap metal and steel. Once popular as a decking and building material, cast iron is also used to create pots and pans that withstand and distribute high heat evenly.
Cast iron is often used as an intermediate step in the creation of steel. There are several ways to obtain steel from the initial iron product, but they all focus on significantly reducing the amount of impurities, especially carbon, in the material. Until the development of steel, iron was a primary building material worldwide, for everything from skyscrapers to steam engine components. Steel, which is lighter, more flexible and stronger than iron, has rapidly surpassed traditional forms of iron to become one of the most widely used materials in the modern world.
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