Method of making CG iron
AssigneeFord Motor Company
InventorsBela V. Kovacs, Roman M. Nowicki
Life of this patent
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Abstract
A method is disclosed for making compacted graphite cast iron of improved strength and hardness while retaining excellent thermal conductivity, low shrinkage, and excellent damping characteristics. A ferrous alloy is melted consisting essentially of, by weight, 3-4% C, 2-3% Si, 0.2-0.7% Mn, 0.25-0.4 Mo, 0.5-3.0% Ni, up to 0.002% sulfur, up to 0.02% phosphorus, and impurities or contaminants up to 1.0%, with the remainder being essentially iron. The melt is subjected to a graphite modifying agent to form compacted graphite upon solidification. The solidified casting is heat treated by austempering and quenching to produce an iron having a matrix of bainite and austenite.
Claims9
A method of making compacted graphite iron, comprising:
- (a) forming a ferrous alloy melt consisting essentially of, by weight, 3-4.0% carbon, 2-3% silicon, 0.2-0.7% manganese, 0.25-0.4% molybdenum, 0.5-3.0% nickel, up to 0.002% sulfur, up to 0.02% phosphorus, and impurities or contaminants up to 1.0%, the remainder being essentially iron, said melt being subjected to a graphite modifying agent in an amount and for a period of time effective to form compacted graphite particles upon solidification;
- (b) solidifying said melt to form a CG iron casting;
- and
- (c) heat treating said iron casting by austempering to produce an iron having a matrix of bainite and austenite.
Dependencies are inferred from the claim text.