A centrifugally cast composite roll for hot rolling comprising an outer layer made of an Fe-based alloy having a chemical composition comprising by mass 2.6-3.6% of C, 0.1-3% of Si, 0.3-2% of Mn, 2.3-5.5% of Ni, 0.5-3.2% of Cr, 0.3-1.6% of Mo, 1.8-3.4% of V, and 0.7-2.4% of Nb, 1.4 ≤V/Nb ≤2.7, a V equivalent (Veq=V+0.55 Nb) being 2.60-4% by mass, and the balance being Fe and impurities, and an inner layer made of an iron-based alloy and integrally fused to the outer layer.

A centrifugally cast composite roll for hot rolling comprising an outer layer made of an Fe-based alloy having a chemical composition comprising by mass 2.6-3.6% of C, 0.1-3% of Si, 0.3-2% of Mn, 2.3-5.5% of Ni, 0.5-3.2% of Cr, 0.3-1.6% of Mo, 1.8-3.4% of V, and 0.7-2.4% of Nb, 1.4 ≤V/Nb ≤2.7, a V equivalent (Veq=V+0.55 Nb) being 2.60-4% by mass, and the balance being Fe and impurities, and an inner layer made of an iron-based alloy and integrally fused to the outer layer.

An inoculant for the manufacture of cast iron with spheroidal graphite is disclosed, the inoculant has a particulate ferrosilicon alloy having between 40 and 80% by weight of Si; 0.02-8% by weight of Ca; 0-5% by weight of Sr; 0-12% by weight of Ba; 0-15% by weight of rare earth metal; 0-5% by weight of Mg; 0.05-5% by weight of Al; 0-10% by weight of Mn; 0-10% by weight of Ti; 0-10 by weight of Zr; the balance being Fe and incidental impurities in the ordinary amount, wherein the inoculant additionally contains, by weight, based on the total weight of inoculant: 0.1 to 15% of particulate Sb.sub.2S.sub.3, and optionally between 0.1 and 15% of particulate Bi.sub.2O.sub.3, and/or between 0.1 and 15% of particulate Sb.sub.2O.sub.3, and/or between 0.1 and 15% of particulate Bi.sub.2S.sub.3, and/or between 0.1 and 5% of one or more of particulate Fe.sub.3O.sub.4, Fe.sub.2O.sub.3, FeO, or a mixture thereof, and/or between 0.1 and 5% of one or more of particulate FeS, FeS.sub.2, Fe.sub.3S.sub.4, or a mixture thereof, a method for producing such inoculant and use of such inoculant.

An inoculant for the manufacture of cast iron with spheroidal graphite is disclosed, the inoculant has a particulate ferrosilicon alloy having between 40 and 80% by weight of Si; 0.02-8% by weight of Ca; 0-5% by weight of Sr; 0-12% by weight of Ba; 0-15% by weight of rare earth metal; 0-5% by weight of Mg; 0.05-5% by weight of Al; 0-10% by weight of Mn; 0-10% by weight of Ti; 0-10 by weight of Zr; the balance being Fe and incidental impurities in the ordinary amount, wherein the inoculant additionally contains, by weight, based on the total weight of inoculant: 0.1 to 15% of particulate Sb.sub.2S.sub.3, and optionally between 0.1 and 15% of particulate Bi.sub.2O.sub.3, and/or between 0.1 and 15% of particulate Sb.sub.2O.sub.3, and/or between 0.1 and 15% of particulate Bi.sub.2S.sub.3, and/or between 0.1 and 5% of one or more of particulate Fe.sub.3O.sub.4, Fe.sub.2O.sub.3, FeO, or a mixture thereof, and/or between 0.1 and 5% of one or more of particulate FeS, FeS.sub.2, Fe.sub.3S.sub.4, or a mixture thereof, a method for producing such inoculant and use of such inoculant.

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).

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).

This ferritic spheroidal graphite cast iron contains 3.0% to 3.6% by mass of C, 4.0% to 5.0% by mass of Si, 0.020% to 0.10% by mass of Mg, 1.0% or less of Mn, 0.10% by mass or less of P, and 0.015% by mass or less of S, with the balance being Fe and inevitable impurities.

This ferritic spheroidal graphite cast iron contains 3.0% to 3.6% by mass of C, 4.0% to 5.0% by mass of Si, 0.020% to 0.10% by mass of Mg, 1.0% or less of Mn, 0.10% by mass or less of P, and 0.015% by mass or less of S, with the balance being Fe and inevitable impurities.

A spheroidal graphite cast iron having an excellent impact strength at low temperature and a method for producing the same are provided. The present disclosure relates to the spheroidal graphite cast iron comprising: C: 3.5 mass % to 4.2 mass %; Si: 2.0 mass % to 2.8 mass %; Mn: 0.2 mass % to 0.4 mass %; Cu: 0.1 mass % to 0.7 mass %; Mg: 0.02 mass % to 0.06 mass %; Cr: 0.01 mass % to 0.15 mass %; and the balance: Fe and inevitable impurities, wherein Mn+Cr+Cu is 0.431 mass % to 1.090 mass %, a graphite nodule count is 230/mm.sup.2 or less, and a pearlite fraction is 30% to 85%.

A spheroidal graphite cast iron having an excellent impact strength at low temperature and a method for producing the same are provided. The present disclosure relates to the spheroidal graphite cast iron comprising: C: 3.5 mass % to 4.2 mass %; Si: 2.0 mass % to 2.8 mass %; Mn: 0.2 mass % to 0.4 mass %; Cu: 0.1 mass % to 0.7 mass %; Mg: 0.02 mass % to 0.06 mass %; Cr: 0.01 mass % to 0.15 mass %; and the balance: Fe and inevitable impurities, wherein Mn+Cr+Cu is 0.431 mass % to 1.090 mass %, a graphite nodule count is 230/mm.sup.2 or less, and a pearlite fraction is 30% to 85%.