Influence of Al and Ti on microstructure and quality of compacted graphite iron castings

Abstract

The contribution is aimed at study of influence of chemical composition of compacted graphite cast iron (CGI) on microstructure and surface quality of castings, particularly on the occurrence of pinholes. It has been found out that aluminium and titanium in CGI effect the formation of this defect in castings. Aluminium content in the range of 0,02 up to 0,1 % is critical. Increased occurrence of pinholes was also determined with Ti contents above 0,1%. On the same set of experimental castings it has been found out that increased contents of those elements on the other hand support the crystallization of compacted graphite. But the utilization of that method for control of CGI microstructure is limited with a possibility of formation of surface defects in castings – pinholes, but also coldshuts and shrinkage cavities.