Abstract: A method for preparing an austempered cast iron which includes an ausferritic matrix, the cast iron having a silicon content of from about 1.6 to about 2.4 weight percent, and a carbon content of from about 1.6 to about 2.2 weight percent, such that the carbon equivalent of the cast iron is from about 2.1 to about 3.0 weight percent. The method includes (a) melting the cast iron composition; (b) pouring the melt into a mold to form a casting having eutectic carbide particles; (c) altering the temperature of the casting to about 1650.degree.-1900.degree. F. and maintaining the temperature of the casting at about 1650.degree.-1900.degree. F. until substantially all of the eutectic carbide particles convert to temper graphite nodules to form a temper graphite-containing casting; (d) cooling the temper graphite-containing casting to about 1500.degree.-1750.degree. F. and maintaining the temperature of the tempered graphite-containing casting at about 1500.degree.-1750.degree. F.

Abstract: A method for producing a selectively surface hardened cast iron part includes uniformly heating the surface of the part by immersion into a molten metallic bath until a desired thickness of surface austenite is produced, and thereafter quenching the heated cast iron part in a liquid quenching bath which is maintained at a temperature of between about 450.degree. to about 800.degree. F. for about 10 minutes to about 4 hours. The resultant selectively surface hardened cast iron part is surface hardened with the bulk of the body of the part remaining untempered. An apparatus for performing this process includes a molten metal bath chamber for containing the molten metal and a molten salt bath quenching chamber for quenching the cast iron parts with a conveyor means extending between the molten metal bath and the molten salt bath chambers. A second conveyor means removes the parts from the molten salt bath chamber.

Abstract: An austemperable cast iron which includes an ausferritic matrix, the cast iron having a silicon content of from about 1.6 to about 2.4 weight percent, and a carbon content of from about 1.6 to about 2.2 weight percent, such that the carbon equivalent of the cast iron is from about 2.1 to about 3.0 weight percent. The austempered cast iron is prepared by melting the cast iron composition; to about 1650.degree.-1900.degree. F. and maintaining the temperature of the casting at that temperature until substantially all of the eutectic carbide particles convert to temper graphite nodules to form a temper graphite-containing casting, then cooling the temper graphite-containing casting to about 1500.degree.-1750.degree. F. and maintaining the temperature of the tempered graphite-coating at about 1500.degree.-1750.degree. F. until a fully austenitic matrix is achieved, and then quenching and cooling the ausferritic matrix casting to room temperature before bainite is formed.