Cast iron

Claim 1

THE PROCESS FOR PRODUCING IMPROVED GRAPHITE STRUCTURES IN MAGNESIUM-CONTAINING GRAY CAST IRON WHICH COMPRISES ESTABLISHING A MOLTEN IRON BATH CONTAINING A RELATIVELY HIGH VALUE OF SULFUR OF AT LEAST ABOUT 0.08% AND HAVING SUCH A COMPOSITION AS TO BE A GRAY CAST IRON WHEN INOCULATED AND CAST, CONDITIONING THE MOLTEN IRON OF SAID BATH BY ADDING TO SAID IRON UNDER A BASIC SLAG CALCIUM IN AN AMOUNT APPROXIMATELY EQUAL ON A WEIGHT BASIS TO THE AMOUNT OF SULFUR IN EXCESS OF 0.02%, SEPARATING SAID SLAG AND THE THUSCONDITIONED MOLTEN IRON FROM EACH OTHER, THEREAFTER INTRODUCING MAGNESIUM INTO SAID CONDITIONED MOLTEN IRON TO RETAIN ABOUT 0.01% TO ABOUT 0.04% MAGNESIUM IN SAID MOLTEN IRON, AND CASTING THE MAGNESIUM-CONTAINING MOLTEN IRON IN AN INOCULATED CONDITION TO OBTAIN A GRAY IRON CASTING CONTAINING ABOUT 0.01% TO ABOUT 0.04% RETAINED MAGNESIUM AND HAVING AN IMPROVED COMPACTED GRAPHITE STRUCTURE FOR THE AMOUNT OF MAGNESIUM RETAINED IN THE CASTING.