The differences between grey and ductile iron are that grey iron is made of flake graphite; this produces a more rigid material and ultimately mass secures the casting in place.
Hall- ja kõrgtugeva malmi erinevus seisneb selles, et hallmalmi valmistatakse grafiidihelvestest; selle tulemusena on saadud materjal jäigem ning valand jääb lõplikult püsima massi abil.