Continuous cast Gray Ironcontains flake graphite in matrix structures that range from all pearlite to pearlite plus ferrite. The matrix structure will influence machinability, strength, hardness and wear characteristics. In general, a fully pearlitic matrix will have the best mechanical properties and will be readily machinable. Bars containing ferrite in the matrix will be easier to machine but will be lower in strength and wear resistance.
Continuous cast Ductile Iron contains nodular graphite in a matrix of pearlite and ferrite. The spheroidal shaped graphite maximizes the strength of cast iron. The ratio of ferrite to pearlite in the matrix varies in each of the three grades in order to produce the required tensile and yield strengths and elongation properties. The nodular graphite provides the same free machining benefits as lead (steel) without the machining and waste disposal problems.