Grey iron is an iron alloy which includes carbon and silicon in addition to the iron, in various concentrations, depending on the needs of the manufacturer producing the alloy. This substance is sometimes referred to as “cast iron,” although cast iron actually includes other iron alloys. Grey iron is very easy and cost effective to make, making it a highly popular iron alloy. Its properties make it highly suitable for a wide range of uses, and examples of this iron alloy can be seen in many locations around the world, including museums which maintain products of historic interest.
This iron alloy has properties which can vary slightly, depending on how quickly it cools and the concentration of various elements in the alloy. The key feature of grey iron is that it includes flakes of graphite which develop during the cooling process. These graphite flakes give grey iron a distinctive gray color when it is fractured, and they are also involved in many of the physical properties of this iron alloy.
Grey iron is not very malleable or strong. It fractures readily, which makes it unsuitable for applications in which high tensile strength is needed. Grey iron also conducts heat very well, which is one reason it is popular for cast iron pans, and it is electrically resistant. The structure of the iron also allows it to dissipate energy very effectively, making it suitable for applications in which people want to dampen mechanical vibrations.
One area where grey iron is very popular is in the manufacturing of machine parts. It is used in engine casings and similar applications where tensile strength is not needed. As a casing, grey iron can provide some shielding from mechanical vibrations. It is available in the form of standardized parts as well as products which have been custom-fabricated by request from users. Many smithies which work with cast iron can fabricate specialty items by request.
Like other metal alloys, grey iron has a series of standardized grades. These grades are set forth by organizations which establish materials standards, and are based on the precise mix of the alloy and the manufacturing process. Using standardized grades is designed to help manufacturers who use iron products, as well as the companies which make alloys. A manufacturer knows exactly what is being purchased when grey iron of a specific alloy is being bought, and a smithy which produces alloys has clear standards to meet when it processes iron.