INFLUENCE OF Al AND Ti ON MICROSTRUCTURE AND QUALITY OF COMPACTED GRAPHITE IRON CASTINGS

Compacted graphite cast iron is a material that again comes forward of the interest of designers and foundries acquiring or improving manufacture of castings from that material. From many publications let us quote three of them from last year 1, 2, 3 . According to the European standard ISO 16 112 this material is called „compacted (vermicular) graphite cast iron“ (the abbreviation CGI that will be used in the next text). Specialized literature of European countries uses sooner the term vermicular graphite. This contribution prefers the term compacted graphite. In the past years we were aimed at study of surface defects – pinholes in castings from compacted graphite cast iron and in particular at influence of cast iron chemical composition on their formation 4, 5 . Elements effecting the pinholes formation, i.e. Al, Ti, Mg and S, have the decisive importance for crystallization of compacted graphite and its share in casting structure. The present contribution is aimed at those problems. Its introduction reminds main conclusions about the mechanism of formation the pinholes in castings. PINHOLES FORMATION