All you need to know about the Cast Iron in our Cast Iron Radiators

‘Cast iron’ is iron or a ferrous alloy which has been heated until it liquifies, and is then poured into a mould to solidify. It is usually made from a raw material known as ‘pig iron’. The alloy constituents of Cast Iron affect its colour when fractured: white cast iron has carbide impurities which allow cracks to pass straight through. Grey cast iron has graphite flakes which deflect a passing crack and initiate countless new cracks as the material breaks.

Carbon (C) and silicon (Si) are the main alloying elements, with the amount ranging from 2.1–4 wt% and 1–3 wt%, respectively. Iron alloys with less carbon content are known as steel. While this technically makes these base alloys ternary Fe–C–Si alloys, the principle of cast iron solidification is understood from the binary iron–carbon phase diagram. Since the compositions of most cast irons are around the eutectic point of the iron–carbon system, the melting temperatures closely correlate, usually ranging from 1,150 to 1,200 °C (2,100 to 2,190 °F), which is about 300 °C (572 °F) lower than the melting point of pure iron.

Cast iron in its purest form tends to be brittle. With its relatively low melting point, good fluidity, castability, excellent machinability, resistance to deformation and wear resistance, cast irons have become an engineering material with a wide range of applications and are used in pipes, machines and automotive industry parts, such as cylinder heads (declining usage), cylinder blocks and gearbox cases (declining usage). It is resistant to destruction and weakening by oxidation (rust).

The earliest cast iron artefacts date to the 5th century BC, and were discovered by archaeologists in what is now Jiangsu in China. Cast iron was used in ancient China for warfare, agriculture, and architecture. During the 15th century, cast iron became utilized for artillery in Burgundy, France, and in England during the Reformation. The first cast iron bridge was built during the 1770s by Abraham Darby III, and is known as The Iron Bridge.

Cast Iron was developed for the manufacture of cast iron radiators in the Victorian era in North America and England when increased skills in making sand cores and moulds were combined with mixing the appropriate graphite content to molten Iron resulted in beautiful and strong cast iron radiators.

Today spectroscopy allow us to regulate exactly the graphite content of cast iron radiators. Too much and the iron becomes too strong and it becomes difficult to cut a thread without shattering the cast iron. Too little and the Iron alloy remains brittle and behaves like glass.

Our cast iron radiators have been developed in association with casting experts and carry a range of guarantees up to 25 years.