The Engineering and physical properties of cast iron wary with the type of iron; the designer must match the engineering requirements with al the properties of the specific type of cast iron being consiered. Machinability, e.g., is significantly affected by the type of cast iron specified. Gray cast iron is the most machinalbe; the white cast irons are the least machinable.
Compositon The properties of cast iron are controlled primarily by the graphite morphology and the quantity of graphite. Also to be considered is the matrix microstructure, which may be established either during cooling from the molten state ( as cast condition) or as a result of heat treatment. Except where previous engineering evaluations have estabished the need for specific chemistry or the cast iron is to be produced to a specific ASTM specification, such that chemistry is a part that will meet the specified mechanical properties and/or graphite morphology.