Valuraudan

Valuraudan, in English cast iron, is a family of iron–carbon alloys with a carbon content typically between about 2.5% and 4%, and silicon often present to promote graphite formation. It is produced by melting iron and pouring the molten metal into molds, yielding components with good fluidity and the ability to take complex shapes at relatively low cost. A key characteristic that distinguishes valuraudan from many steels is its higher carbon content and a microstructure that affects machinability, hardness, and brittleness.

Common forms include gray cast iron, which contains graphite flakes that provide good damping and machinability but lower tensile strength and ductility; white cast iron, which contains cementite and is very hard and brittle yet can be heat-treated to create wear-resistant components; ductile (nodular) cast iron, where graphite is present as nodules, offering higher ductility and toughness; and malleable cast iron, which is heat-treated to form clusters of carbon that improve ductility compared with white iron.

Production typically involves melting iron in a blast furnace or electric furnace, followed by alloying to achieve the desired carbon content and graphite form. Gray iron is promoted by silicon additions; ductile iron requires magnesium or cerium to promote nodular graphite. After pouring into molds, the cooling rate and composition determine the final microstructure and properties.

Applications include engine blocks and cylinders, pipes and fittings, automotive components, cookware, and machinery bases. Cast iron provides high compressive strength, wear resistance in some forms, and good damping, but reduced toughness and weldability in others.

Valuraudan has a long industrial history and remains widely used where castability and wear resistance are prioritized. Recycling of scrap iron is common to sustain production and reduce environmental impact.