A high rigid spheroidal graphite cast iron, comprising: 2.0 mass % to less than 2.7 mass % or more than 3.0 mass % to less than 3.6 mass % of C, 1.5 to 3.0 mass % of Si, 1.0% or less of Mn, 1.0 mass % or less of Cu, 0.02 to 0.07 mass % of Mg and the residual Fe and inevitable impurities, wherein a carbon equivalent (a CE value) calculated by the mathematical expression (1): CE=C (mass %)+Si (mass %)/3 in terms of C and Si contents is 2.8 to 3.2% within a first range from 2.0 mass % to less than 2.7 mass % of C and is 3.6 to 4.2% within a second range from more than 3.0 mass % to less than 3.6 mass % of C, and the Young's modulus is 170 GPa or more.

A high rigid spheroidal graphite cast iron, comprising: 2.0 mass % to less than 2.7 mass % or more than 3.0 mass % to less than 3.6 mass % of C, 1.5 to 3.0 mass % of Si, 1.0% or less of Mn, 1.0 mass % or less of Cu, 0.02 to 0.07 mass % of Mg and the residual Fe and inevitable impurities, wherein a carbon equivalent (a CE value) calculated by the mathematical expression (1): CE=C (mass %)+Si (mass %)/3 in terms of C and Si contents is 2.8 to 3.2% within a first range from 2.0 mass % to less than 2.7 mass % of C and is 3.6 to 4.2% within a second range from more than 3.0 mass % to less than 3.6 mass % of C, and the Young's modulus is 170 GPa or more.

A method of manufacturing a cam piece for a continuously variable valve duration and a cam piece manufactured therefrom, and more particularly, to material and heat treatment conditions of a cam piece, may include manufacturing a cam piece by casting; heating the cam piece; maintaining a heating temperature; and salt-bathing the cam piece, in which the cam piece includes 3.2 to 4.2 wt % of carbon (C), 2.2 to 3.4 wt % of silicon (Si), and the balance iron (Fe), and may have a carbon equivalent value of 4.4 to 4.6.

A method of manufacturing a cam piece for a continuously variable valve duration and a cam piece manufactured therefrom, and more particularly, to material and heat treatment conditions of a cam piece, may include manufacturing a cam piece by casting; heating the cam piece; maintaining a heating temperature; and salt-bathing the cam piece, in which the cam piece includes 3.2 to 4.2 wt % of carbon (C), 2.2 to 3.4 wt % of silicon (Si), and the balance iron (Fe), and may have a carbon equivalent value of 4.4 to 4.6.

A cast iron alloy is provided with a composition in weight percent (wt. %) of carbon between 2.6 to 3.4 wt. %, silicon between 2.4 to 3.2 wt. %, manganese between 0.3 to 0.6 wt. %, molybdenum between 0.4 to 1.2 wt. %, nickel between 0.6 to 1.75 wt. %, magnesium between 0.01 to 0.075 wt. %, aluminum between 1.8 to 3.5 wt. %, sulfur between 0.003 to 0.025 wt. %, zirconium between 0.001 to 0.02 wt. %, cerium between 0.001 to 0.03 wt. %, lanthanum between 0.0005 to 0.02 wt. %, and a balance of iron and unavoidable trace elements. A part formed from the cast iron alloy is also provided and the part has an Ac1 temperature equal to or greater than 895° C. and a thermo-mechanical fatigue lifetime of at least 10,000 cycles when cycled between 400° C. to 800° C. with a total cyclic strain equal to 0.001 m/m.

A cast iron alloy is provided with a composition in weight percent (wt. %) of carbon between 2.6 to 3.4 wt. %, silicon between 2.4 to 3.2 wt. %, manganese between 0.3 to 0.6 wt. %, molybdenum between 0.4 to 1.2 wt. %, nickel between 0.6 to 1.75 wt. %, magnesium between 0.01 to 0.075 wt. %, aluminum between 1.8 to 3.5 wt. %, sulfur between 0.003 to 0.025 wt. %, zirconium between 0.001 to 0.02 wt. %, cerium between 0.001 to 0.03 wt. %, lanthanum between 0.0005 to 0.02 wt. %, and a balance of iron and unavoidable trace elements. A part formed from the cast iron alloy is also provided and the part has an Ac1 temperature equal to or greater than 895° C. and a thermo-mechanical fatigue lifetime of at least 10,000 cycles when cycled between 400° C. to 800° C. with a total cyclic strain equal to 0.001 m/m.

A ductile iron composition including, by weight: about 3.4% to about 4.0% Si; about 3.0% to about 3.5% C; about 0.5% to about 1.0% Cr; about 0.02% to about 0.05% Mo; up to about 0.01% S; up to about 0.5% Mn; and balance iron and incidental impurities.

The composition has a a ferritic body center cubic microstructure and has a graphite nodule density of greater than 100 per mm.sup.2. A method for forming a ductile iron composition is also disclosed.

A ductile iron composition including, by weight: about 3.4% to about 4.0% Si; about 3.0% to about 3.5% C; about 0.5% to about 1.0% Cr; about 0.02% to about 0.05% Mo; up to about 0.01% S; up to about 0.5% Mn; and balance iron and incidental impurities.

The composition has a a ferritic body center cubic microstructure and has a graphite nodule density of greater than 100 per mm.sup.2. A method for forming a ductile iron composition is also disclosed.

A ductile iron composition including, by weight: about 3.1% to about 3.6% C; about 3.5% to about 4.0% Si; about 0.035% to about 0.050% Mg; about 0.001% to about 0.004% Ce; up to about 0.005% Sb; about 0.008% to about 0.016% S; up to about 0.04% P; up to about 0.3% Mn; and balance iron and incidental impurities;
The ductile iron composition includes a ratio of Sb/Ce greater than or equal to about 1.25, has a ferritic microstructure and graphite nodules, and greater than about 65% of the graphite nodules having a highly spherical geometry. A method and apparatus for forming a ductile iron composition are also disclosed.

A ductile iron composition including, by weight: about 3.1% to about 3.6% C; about 3.5% to about 4.0% Si; about 0.035% to about 0.050% Mg; about 0.001% to about 0.004% Ce; up to about 0.005% Sb; about 0.008% to about 0.016% S; up to about 0.04% P; up to about 0.3% Mn; and balance iron and incidental impurities;
The ductile iron composition includes a ratio of Sb/Ce greater than or equal to about 1.25, has a ferritic microstructure and graphite nodules, and greater than about 65% of the graphite nodules having a highly spherical geometry. A method and apparatus for forming a ductile iron composition are also disclosed.