A nodular iron alloy and automotive components, such as differential and drive axle components, are provided. The nodular iron alloy may include iron, about 3.1-3.3 wt % carbon, about 2.7-4.3 wt % silicon, about 0.15-0.40 wt % manganese, about 0-0.10 wt % magnesium, about 0-0.2 wt % nickel, about 0-0.4 wt % copper, about 0-0.30 wt % chromium, about 0-0.03 wt % phosphorus, and about 0-0.02 wt % sulfur. The nodular iron alloy may have an ultimate tensile strength of at least 620 MPa as-cast. This alloy possesses favorable weldability to weld with steel components without substantial preheating or post heat treatment for a strong and tough weldment, and it has good machinability to facility comprehensive machining operations.

A nodular iron alloy and automotive components, such as differential and drive axle components, are provided. The nodular iron alloy may include iron, about 3.1-3.3 wt % carbon, about 2.7-4.3 wt % silicon, about 0.15-0.40 wt % manganese, about 0-0.10 wt % magnesium, about 0-0.2 wt % nickel, about 0-0.4 wt % copper, about 0-0.30 wt % chromium, about 0-0.03 wt % phosphorus, and about 0-0.02 wt % sulfur. The nodular iron alloy may have an ultimate tensile strength of at least 620 MPa as-cast. This alloy possesses favorable weldability to weld with steel components without substantial preheating or post heat treatment for a strong and tough weldment, and it has good machinability to facility comprehensive machining operations.

A nodular iron alloy and automotive components, such as crankshafts, are provided. The nodular iron alloy may include iron, about 3.3-3.9 wt % carbon, about 0.2-0.5 wt % manganese, about 1.9-2.6 wt % silicon, about 0.15-0.30 wt % copper, about 0.03-0.06 wt % magnesium, about 0-0.02 wt % sulfur, about 0-0.1 wt % chromium, about 0-0.05 wt % phosphorus, and/or about 0-0.01 wt % tin. The nodular iron alloy may include a number of graphite nodules, each having a diameter between 15 and 120 micrometers, and the graphite nodules having a number density of at least 90 per square millimeter. Iron may surround the graphite nodules in an amount of 20-40% of a ferrite microstructure and 60-80% of a pearlite microstructure. The nodular iron alloy may have an ultimate tensile strength in the range of 550 MPa to 680 MPa as-cast and at least 80% nodularity.

The present invention provides a die-cast product producing method and a spheroidizing agent of a spherical graphite cast iron with ultrafine spherical graphite by simple method and good reproducibility.

The present invention provides a sand mold producing method and a spheroidizing agent capable of producing an ultrafine spherical graphite cast iron with good reproducibility even in a sand mold thin walled spherical graphite cast iron, which has solidification cooling conditions equivalent to those of a metal mold.

The present invention provides a producing method of a die-cast product of a spherical graphite cast iron using a spheroidizing agent, in which a C amount is 0.5 mass % or more, a total nitrogen amount N is 150 ppm (by mass) or less, and a nitrogen amount generated during melting is 15 ppm (by mass) or less, in a producing method of a sand mold cast product of a thin walled spherical graphite cast iron having a melting process, a spheroidizing process, an inoculation process, and a casting process.

The present invention refers to a vermicular cast iron alloy specially designed for internal combustion engine blocks and heads having special requirements of mechanical strength and fatigue strength. Vermicular iron alloy with high mechanical strength and high fatigue strength for the production of internal combustion engines blocks and heads characterized by having a microstructure of pearlitic matrix and predominantly vermicular graphite (>70%) and presence of graphite nodules in up to 30%, wherein its graphite microstructure is described by the Microstructure Factor (FM), as defined below, with Microstructure Factor values higher than 0.94.

The invention provides a method for increasing the quality of graphite balls. The method comprises melting molten iron in an electric furnace, increasing the sulfur content in the molten iron during the melting process, and adding rare earth in the electric furnace or in a nodularizing ladle; after the molten iron is completely melted, pouring the molten iron into the nodularizing ladle and nodularizing; and after nodularization, adding ferromanganese to a transfer ladle. In the present invention, sulfur is added to molten iron in advance, and rare earth is added to a nodularizing ladle previously, so that a large number of dispersed rare earth sulfide particles are formed in the molten iron during the nodularization process. Rare earth sulfide particles serve as the nuclei of graphite crystallization to increase the number of graphite balls, and improve the roundness of graphite balls.

The invention provides a method for increasing the quality of graphite balls. The method comprises melting molten iron in an electric furnace, increasing the sulfur content in the molten iron during the melting process, and adding rare earth in the electric furnace or in a nodularizing ladle; after the molten iron is completely melted, pouring the molten iron into the nodularizing ladle and nodularizing; and after nodularization, adding ferromanganese to a transfer ladle. In the present invention, sulfur is added to molten iron in advance, and rare earth is added to a nodularizing ladle previously, so that a large number of dispersed rare earth sulfide particles are formed in the molten iron during the nodularization process. Rare earth sulfide particles serve as the nuclei of graphite crystallization to increase the number of graphite balls, and improve the roundness of graphite balls.

The present invention provides a casting method and cast product of spherical graphite cast iron, in which, even with a small modulus, there is no chill, the spherical graphite in the tissue is further made ultrafine, the dispersion of the particle diameter is small, and the number of the particles is several times that of the conventional one in the as cast state where heat treatment is not carried out. A casting method of a spherical graphite cast iron includes a melting process, a spheroidizing treatment process, an inoculation process, and a casting process, in which the original molten metal after the inoculation process is poured and filled up to a product space through a gate of a metal mold; where the original molten metal is controlled to a semi-solidification temperature range, before being filled up to the product space.

The present invention provides a casting method and cast product of spherical graphite cast iron, in which, even with a small modulus, there is no chill, the spherical graphite in the tissue is further made ultrafine, the dispersion of the particle diameter is small, and the number of the particles is several times that of the conventional one in the as cast state where heat treatment is not carried out. A casting method of a spherical graphite cast iron includes a melting process, a spheroidizing treatment process, an inoculation process, and a casting process, in which the original molten metal after the inoculation process is poured and filled up to a product space through a gate of a metal mold; where the original molten metal is controlled to a semi-solidification temperature range, before being filled up to the product space.

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).