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Casting begins with the choice of the basic chemical composition. This composition determines the raw materials to be used in the melting process, the treatment of the cast iron in its liquid state, and the determination of loss or gain on ignition. As a general rule, the specifications of the cast part to be supplied are characterized by the mechanical and physical properties of the material used to manufacture it. These characteristics depend on both the final chemical composition and the microstructure of the cast iron. This microstructure is largely influenced by cooling rates during solidification and in the solid state, and by the material's treatments in the liquid state. It is up to the melter to choose the initial basic chemical composition and the melting media to be used to meet the specifications. The choice of melting means used also depends on the flow of liquid alloy to be supplied to the casting site, and on its flexibility.

Some of the required characteristics can only be achieved by using high alloying element contents. For special cast irons, alloying element contents are governed by standards; in SNCF brake shoes, for example, phosphorus content is tightly specified for lamellar graphite cast iron.

Workshop controls are set up to predict the microstructure and composition of the cast iron in order to optimize the cost of production and to intervene by treating the cast iron in its liquid state. These pre-casting controls help avoid rejects due to non-conformity of chemical composition or microstructure.

The article describes all the metallurgical operations involved in obtaining a liquid cast iron suitable for casting, and the various operations required to prepare the liquid alloy, in terms of quantity and quality, to fill the molds prepared on the casting sites.