Influence of Carbide-Promoting Elements on the Pearlite Content and the Tensile Properties of High Silicon SSDI Ductile Iron

Steel scrap is one of the most important raw materials for the production of ductile iron (DI) because of its low cost. Most low alloyed steels contain carbide-promoting elements such as chromium, manganese, molybdenum and niobium and are currently not used for the production of DI because of their negative impact on the mechanical properties. The solid solution strengthened DI grades (SSDI) exhibit an increased tolerance toward carbide-promoting elements and thus allow the production of ferritic DI using low alloyed steel scrap. Therefore, the tolerance limits of these elements need to be identified. The following article shows the influence of low contents of Cr, Mn, Mo and Nb on the microstructure and the tensile properties of the SSDI grade EN-GJS-500-14. The results indicate that even low levels of chromium and molybdenum have a negative impact on tensile properties, whereas manganese and niobium are tolerable up to much higher levels.