The present disclosure provides a method for controlling an amount of silicon added to ductile cast iron, a method for casting ductile cast iron, and a cast product, which relate to the technical fields of metallurgical and cast iron alloys. The method for controlling an amount of silicon added to ductile cast iron includes smelting ductile cast iron using scrap steel as a raw material. After the scrap steel is melted into molten iron, a copper alloy is added so that the molten iron has a copper equivalent of 0.8% to 1.0%, wherein the copper equivalent is controlled by formula (II). Then, ferrosilicon is added so that the content of silicon added to the molten iron satisfies formula (I).

A spheroidal graphite cast iron having a chemical composition of: C: 3.0% to 4.0%, Si: 2.0% to 2.4%, Cu: 0.20% to 0.50%, Mn: 0.15% to 0.35%, S: 0.005% to 0.030%, Mg: 0.03% to 0.06%, each by mass, and the balance being Fe and inevitable impurities, where Mn and Cu are contained at 0.45% to 0.75% in total; and a structure in which a ferrite layer encloses spheroidal graphite crystallized out in a matrix of pearlite. Part of the pearlite is extended from the matrix side to the spheroidal graphite side to divide the ferrite layer at one or more areas.

A spheroidal graphite cast iron having a chemical composition of: C: 3.0% to 4.0%, Si: 2.0% to 2.4%, Cu: 0.20% to 0.50%, Mn: 0.15% to 0.35%, S: 0.005% to 0.030%, Mg: 0.03% to 0.06%, each by mass, and the balance being Fe and inevitable impurities, where Mn and Cu are contained at 0.45% to 0.75% in total; and a structure in which a ferrite layer encloses spheroidal graphite crystallized out in a matrix of pearlite. Part of the pearlite is extended from the matrix side to the spheroidal graphite side to divide the ferrite layer at one or more areas.

A composite roll for rolling having a structure comprising centrifugally cast outer and intermediate layers of an Fe-based alloy integrally fused to an inner layer of ductile cast iron; the outer layer having a composition comprising by mass 1-3% of C, 0.3-3% of Si, 0.1-3% of Mn, 0.5-5% of Ni, 1-7% of Cr, 2.2-8% of Mo, 4-7% of V, 0.005-0.15% of N, and 0.05-0.2% of B, the balance being Fe and inevitable impurities; the intermediate layer containing 0.025-0.15% by mass of B; the B content in the intermediate layer being 40-80% of that in the outer layer; and the total amount of Cr, Mo, V, Nb and W in the intermediate layer being 40-90% of that in the outer layer.

A cast iron material and methods for using same are disclosed, as well as a method for producing and/or lining a mould. The cast iron material has a change in length at temperatures of ?60? C. to 440? C., more particularly in the temperature range from 0? C. to 420? C., which change in length is as small as possible or as similar as possible to that of carbon fibre reinforced polymer or glass-fibre reinforced plastic. The cast iron material has at least the following proportions in percent by weight as elements or as compounds of carbon in the range from approximately 1.5% to 4.0%, silicon in the range from approximately 1.0% to 5.0%, manganese in the range from approximately 0.1% to 1.5%, nickel in the range from approximately 36.5% to 48.0%, chrome in the range from approximately 0.01 to 0.25%, phosphorus to approximately 0.08%, copper to approximately 0.5%, magnesium to approximately 0.150%, the remainder being iron and unavoidable impurities.

A cast iron material and methods for using same are disclosed, as well as a method for producing and/or lining a mould. The cast iron material has a change in length at temperatures of ?60? C. to 440? C., more particularly in the temperature range from 0? C. to 420? C., which change in length is as small as possible or as similar as possible to that of carbon fibre reinforced polymer or glass-fibre reinforced plastic. The cast iron material has at least the following proportions in percent by weight as elements or as compounds of carbon in the range from approximately 1.5% to 4.0%, silicon in the range from approximately 1.0% to 5.0%, manganese in the range from approximately 0.1% to 1.5%, nickel in the range from approximately 36.5% to 48.0%, chrome in the range from approximately 0.01 to 0.25%, phosphorus to approximately 0.08%, copper to approximately 0.5%, magnesium to approximately 0.150%, the remainder being iron and unavoidable impurities.

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.

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.

A spheroidal graphite cast iron comprising, in mass percentage: 2.8% or more and 3.3% or less of carbon; 2.5% or more and 4.0% or less of silicon; 0.32% or more and 0.40% or less of manganese; 0.020% or more and 0.030% or less of phosphorus; 0.020% or more and 0.035% or less of sulfur; 0.030% or more and 0.050% or less of magnesium; 0.010% or more and 0.050% or less in total of lanthanum and cerium; and 0.0020% or more and 0.0050% or less of calcium, with the balance being iron and inevitable impurities.

A spheroidal graphite cast iron comprising, in mass percentage: 2.8% or more and 3.3% or less of carbon; 2.5% or more and 4.0% or less of silicon; 0.32% or more and 0.40% or less of manganese; 0.020% or more and 0.030% or less of phosphorus; 0.020% or more and 0.035% or less of sulfur; 0.030% or more and 0.050% or less of magnesium; 0.010% or more and 0.050% or less in total of lanthanum and cerium; and 0.0020% or more and 0.0050% or less of calcium, with the balance being iron and inevitable impurities.