Ductile iron alloys and materials including a thin-wall layer of a ductile iron alloy

Abstract

The instant disclosure relates to ductile iron alloy compositions and articles that can maintain desired microstructural and mechanical properties even when cast to make thin-wall samples. Particularly, the compositions herein may maintain hardness and ductility and minimize carbide formation even when cast in samples as thin as about 1 mm to about 6 mm. In particular, the instant disclosure relates to a cast iron alloy composition including nodular or spheroidal graphite domains comprising an iron content of at least about 90% by weight, a remaining alloy content of less than about 10% by weight, about 0.65% to about 0.85% by weight copper, about 3.6% to about 4.2% by weight silicon, and about 3.4% to about 3.8% by weight carbon.

What is claimed is: 
     
         1 . A cast iron alloy composition including nodular or spheroidal graphite domains comprising:
 an iron content of at least about 90% by weight;   a remaining alloy content of less than about 10% by weight;   about 0.65% to about 0.85% by weight copper;   about 3.6% to about 4.2% by weight silicon; and   about 3.4% to about 3.8% by weight carbon.   
     
     
         2 . The cast iron alloy of  claim 1  wherein said nodular or spheroidal graphite domains are present in an amount of greater than about 5% by volume with respect to the total volume of said cast iron alloy composition. 
     
     
         3 . The cast iron alloy composition of  claim 1  comprising aluminum in an amount less than about 0.8% by weight. 
     
     
         4 . The cast iron alloy composition of  claim 1  comprising molybdenum in an amount of less than about 0.04% by weight. 
     
     
         5 . The cast iron alloy composition of  claim 1  wherein said composition is substantially free of aluminum, molybdenum, and niobium. 
     
     
         6 . The cast iron alloy composition of  claim 1  comprising manganese in an amount of between about 0.1% to about 0.5% by weight. 
     
     
         7 . The cast iron alloy composition of  claim 1  comprising magnesium in an amount of between about 0.03% to about 0.06% by weight. 
     
     
         8 . The cast iron alloy composition of  claim 1  further comprising:
 about 40% to about 70% by volume of ferrite domains with respect to the total volume of said cast iron alloy composition; and 
 about 15% to about 50% by volume of pearlite domains with respect to the total volume of said cast iron alloy composition. 
 
     
     
         9 . The cast iron alloy composition of  claim 1  further comprising:
 a carbide content of less than about 1% by volume with respect to the total volume of said cast iron alloy composition; 
 a sum amount of a ferrite domain volume percentage and a pearlite domain volume percentage of greater than about 85% by volume with respect to the total volume of said cast iron alloy composition; and 
 a ratio of said ferrite domain volume percentage to said pearlite domain volume percentage of about 0.75:1 to about 1.25:1. 
 
     
     
         10 . An article including a cast iron alloy composition including nodular or spheroidal graphite domains comprising:
 an iron content of at least about 90% by weight;   a remaining alloy content of less than about 10% by weight;   about 0.65% to about 0.85% by weight copper;   about 3.6% to about 4.2% by weight silicon; and   about 3.4% to about 3.8% by weight carbon.   
     
     
         11 . The article of  claim 10  comprising a thin-wall part including a thickness in at least one dimension of between about 1.5 mm and about 2.5 mm. 
     
     
         12 . The article of  claim 11  comprising carbide in an amount of less than about 1% by volume. 
     
     
         13 . The article of  claim 11  wherein said thickness in at least one dimension is an as-cast thickness. 
     
     
         14 . The article of  claim 11  wherein said thin-wall part comprises:
 a sum amount of a ferrite domain percentage and a pearlite domain percentage of greater than about 85% by volume with respect to the total volume of said thin-wall part; and 
 wherein a ratio of said ferrite domain percentage to said pearlite domain percentage is between about 0.75:1 to about 1.25:1. 
 
     
     
         15 . The article of  claim 10  comprising a first thin-wall part including a thickness in at least one dimension of between about 1.5 mm and about 2.5 mm and a second part including a thickness of greater than about 6.0 mm;
 wherein said first thin-wall part includes a first ratio of a ferrite domain percentage by volume to a pearlite domain percentage by volume of about 0.75:1 to about 1.25:1; and 
 wherein said second part includes a second ratio of ferrite domain percentage by volume to pearlite domain percentage by volume of greater than about 4.5:1. 
 
     
     
         16 . The article of  claim 10  comprising aluminum in an amount of less than about 0.8% by weight. 
     
     
         17 . The article of  claim 10  comprising molybdenum in an amount of less than about 0.04% by weight. 
     
     
         18 . The article of  claim 10  wherein said article is substantially free of aluminum, molybdenum, and niobium. 
     
     
         19 . The article of  claim 10  comprising manganese in an amount of between about 0.1% to about 0.5% by weight. 
     
     
         20 . The article of  claim 10  comprising magnesium in an amount of between about 0.03% to about 0.06% by weight.