Gray iron casting process and composition

Claim 1

IN A CONTINUOUS PROCESS OF MAKING GRAY IRON CASTINGS NOT SUSCEPTIBLE TO SELF ANNEALING AFTER POURING IN THE MOLD, AND PRIOR TO CORE KNOCKOUT, WHERE SAID CASTING ARE SLOWLY COOLED ON A MOVING LINE SUBJECT TO STOPPAGES WHICH WOULD CAUSE SUCH SELF-ANNEALING OF THE CASTINGS AND A SOFT MATRIX IN THE WEAR AREAS OF THE CASTINGS HAVING A HARDNESS SUBSTANTIALLY BELOW 170 BRINELL AND A MICROSTRUCTURE CONTAINING IN EXCESS OF 5% UNIFORMLY DISPERSED FREE FERRITE, THE STEP WHICH ONSISTS IN ADDING TO THE MOLTEN GRAY IRON COMPOSITION PRIOR TO POURING, BETWEEN 0.04 TO 0.25% BY WEIGHT OF THE COMPOSITION OF TIN TO SUBSTANTIALLY ELIMINATE SELF ANNEALING AND TO FACILITATE THE PRODUCTION OF CASTINGS HAVING A MATRIX IN THE WEAR AREA THEREOF OF BETWEEN 170 TO 241 BRINELL HARDNESS AND A MICROSTRUCTURE OF FINE PEARLITE CONTAINING NOT MORE THAN ABOUT 5% UNIFORMLY DISPERSED FREE FERRITE, REGARDLES OF SAID LINE STOPPAGES.