9 - Effects of Trace Elements and Composition Variables on the Annealing Time of Ductile Iron

Abstract:

The desired microstructure in most applications for ductile iron consists of graphite spheroids in a matrix of ferrite, pearlite, or some combination of the two matrices, designed to develop specified mechanical properties, but generally with freedom from carbide. The occurance of carbide, ferrite and pearlite is dependent upon a number of factors such as cooling rate of the casting, variations in the normal chemistry or amount of certain trace elements. These latter generally are present inadvertently, having been present in the charge materials and they seem to be on the gradual increase in scrap materials.