Effect of process parameters on the characteristics of ductile cast irons.

Ductile cast irons are ferrous alloys in which there is a metallic matrix with graphite precipitation in the form of nodules. Their industrial use is focused on parts that require moderate ductility without reduction on mechanical strength, such as valves, automotive parts and hardware tools.  Its characteristics and therefore the quality are influenced by the microstructure of the matrix and the morphology of graphite nodules. All of these features are associated with the processing parameters and in order to achieve good properties, there are some variables that are desirable to control.

This work presents the effects of pouring temperature; time elapsed since chemical treatments (nodulation and inoculation) and thickness in the final characteristics of ductile iron under real process conditions that are found in production of cast parts.  It was found that the best periods of time for pouring the melt iron is between the second and fifth minutes after inoculation to obtain a good nodule count with non degenerated graphite.  It was also found that raw materials contaminated with chromium adversely affect the morphological characteristics of ductile cast irons.