CAST IRON INDEFINITE CHILL ROLL PRODUCED BY THE ADDITION OF NIOBIUM.

摘要

An indefinite chill roll alloy composition is disclosed containing carbon ranging from 2.5 to 4.0 percent by weight of the alloy and the carbon is present as free graphite in an amount ranging from 2-7 percent, preferably 3-6 percent, of the total carbon. The composition further includes niobium which ranges from 0.3-6.0 percent and is present essentially as discrete niobium carbide particles in the alloy. The present invention further includes a chill roll shell formed from the alloy and produced by a method including the steps of providing a molten indefinite chill roll composition, adjusting the composition by adding niobium in an amount sufficient to produce a molten batch containing 0.3 to 6.0 percent niobium based on the total weight of said molten batch, providing a stoichiometric amount of excess carbon to form niobium carbide and casting the molten batch to form the chill roll shell. The method of the present invention may be useful to form indefinite chill roll containing significant quantities of carbides from other element that form carbides having low carbide solubilities near the eutectic point of the iron alloy, while maintaining sufficient free graphite in the alloy to produce an alloy having the properties required for chill roll applications.