Abstract: The combinational use of alloying elements with positive and negative segmpation hasbeen shown to be very thective in strengthening the matrix of cast iron. Negativesegmpation alloying elements, Cu and Si, make the inner parts of dendritic austenitesand eutectic cells get good handenability. On the contrury, positive segmpation alloyingelements Cr and Mn make the outer parts of dendrites have higher microhaofness.Appropriate combination of the above two tyPes Of alloying elements can produce auniform microharkness and high strength in grny cast irons.

Key words: cast iron, positive and negative segregation of alloying element, microhardness