Are used to treat melts in covered ladles to produce spheroidal graphite cast irons having a pearlitic matrix (GGG60 and GGG70) from which castings are made. These cast irons have low silicon contents and high magnesium and barium contents. This combination makes it possible to obtain consistent globular graphite form over the entire cross section of castings. Barium also promotes formation of additional crystallization centers. When treating melts in covered ladles by means of the sandwich process, magnesium is recovered to the greatest possible degree and the spheroidizing effect lasts as long as necessary.
All Spheromax® spheroidizers can dissociate in irons at low temperatures, which makes it possible to modify cupola irons with sulfur content up to 0.12% without prior desulfuration and to produce spheroidal graphite cast irons having a pearlitic matrix and spheroidal graphite cast irons having ferritic and pearlitic matrices from which castings are made.