Method for increasing mechanical properties in ductile iron by alloy additions
AssigneeFord Motor Company
InventorBela V. Kovacs
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Abstract
A method is disclosed of making as-cast ductile iron wherein an iron melt having a chemistry capable of forming gray iron having flake graphite is treated with a nodularizing agent and solidified to provide a microstructure consisting substantially of a pearlite matrix containing uniformly distributed graphite nodules surrounded by ferrite. The iron melt is alloyed with: (a) at least one of 0.02-0.06% Sb and 0.02-0.08% Sn, (b) 0.001-0.0015% each of Ce and La, and (c) 0.5-1.0% Mn.
Claims9
In a method of making an as-cast ductile iron casting, wherein a basic melt of carbon, silicon, manganese and iron is treated with a nodularizing agent and cooled to provide a microstructure consisting substantially of a pearlitic matrix containing cementite and graphite nodules surrounded by ferrite, the improvement comprising:
- alloying said melt with the following combination of pearlitic stabilizers in percentage weight of the melt:
- (a) at least one of 0.02-0.06% Sb and 0.02-0.08% Sn, (b) 0.001-0.0015% Ce and 0.001-0.0015% La, and (c) 0.5-1.0% manganese.
In a method of making an as-cast ductile iron casting from a melt comprising 3.0-4.1% carbon, 1.8-2.8% silicon, 0.5-0.8% manganese, no greater than 0.015% sulfur, no greater than 0.06% phosphorus and the remainder being iron, the casting having an increased yield strength, hardness and fatigue resistance, the steps comprising:
- alloying with said melt, by percentage weight of the melt, the following ingredients:
- at least one of 0.02-0.04% antimony and 0.02-0.06% tin, 0.001-0.0015% each of Ce and La, said ingredients and manganese together constituting 0.2-1.0% of the melt;
- and
- treating said alloyed melt with a nodularizing agent so that upon cooling the resulting cast iron will contain a pearlitic matrix having uniformly distributed graphite nodules with the nodules surrounded by ferrite as well as cementite.
A method of strengthening ductile iron by alloying the ductile iron matrix with (a) at least one of 0.02-0.06% by weight Sb and 0.02-0.08% Sn, and (b) 0.5-1.0% Mn.
Dependencies are inferred from the claim text.