A nodular graphite cast iron for pistons according to an embodiment contains, in mass %, C: 2.7 to 4.3%, Si: 2.0 to 3.5%, Mn: 0.3 to 0.8%, Mg: 0.02 to 0.10%, Cu: 0.3 to 1.0%, Cr: 0.05 to 0.90%, and Mo: 0.05 to 1.00% with the balance being composed of Fe and inevitable impurities. Then, the C content and the Si content fall within a composition range defined by a line sequentially joining respective points of point A (2.7%, 3.5%), point B (3.2%, 2.0%), point C (4.3%, 2.0%), and point D (3.8%, 3.5%) indicated by (the C content and the Si content) in a graph illustrating the relation between the C content and the Si content.

The present disclosure relates to a manufacturing method of high-strength flake graphite cast iron, the high-strength flake graphite cast iron manufactured by the method, and an engine body including the cast iron, and more particularly, to flake graphite cast iron and a manufacturing method thereof, wherein the flake graphite cast iron has a uniform graphite shape and low probability of forming chill and has high tensile strength of at least 350 MPa and excellent workability and fluidity by controlling the content of manganese (Mn) and a trace of strontium (Sr), which are included in the cast iron, within a specific ratio.

The present disclosure relates to a manufacturing method of high-strength flake graphite cast iron, the high-strength flake graphite cast iron manufactured by the method, and an engine body including the cast iron, and more particularly, to flake graphite cast iron and a manufacturing method thereof, wherein the flake graphite cast iron has a uniform graphite shape and low probability of forming chill and has high tensile strength of at least 350 MPa and excellent workability and fluidity by controlling the content of manganese (Mn) and a trace of strontium (Sr), which are included in the cast iron, within a specific ratio.

A centrifugally cast, hot-rolling composite roll comprising an outer layer formed by a centrifugal casting method, and an inner layer made of ductile cast iron and integrally fused to the outer layer; the outer layer having a chemical composition comprising by mass 1-3% of C, 0.4-3% of Si, 0.3-3% of Mn, 1-5% of Ni, 2-7% of Cr, 3-8% of Mo, 3-7% of V, and 0.01-0.12% of B, the balance being Fe and inevitable impurities, and meeting the relation expressed by Cr/(Mo+0.5W)<−2/3[C−0.2(V+1.19Nb)]+11/6, wherein W=0, and Nb=0, when W and Nb are not contained; and containing by area 1-15% of MC carbide, 0.5-20% of carboboride, and 0.5-20% of Mo-based carbide.

A cast iron having high strength, hardness, and thermal conductivity for a cylinder liner of an internal combustion engine is provided. The cast iron includes 3.2 wt. % to 3.8 wt. % carbon, 2.2 wt. % to 3.2 wt. % silicon, 0.5 wt. % to 1.3 wt. % copper, and at least 75.0 wt. % iron, based on the total weight of the cast iron. The cast iron further includes 0.01 wt. % to 0.5 wt. % manganese, 0.01 wt. % to 0.2 wt. % chromium, up to 0.3 wt. % phosphorous, up to 0.05 wt. % sulfur, up to 0.2 wt. % tin, and up to 0.1 wt. % magnesium, based on the total weight of the cast iron. Preferably, the cast iron is free of molybdenum, nickel, and vanadium. The cast iron is also heat treated and solidifies to achieve fully spheroidal graphite.

A cast iron having high strength, hardness, and thermal conductivity for a cylinder liner of an internal combustion engine is provided. The cast iron includes 3.2 wt. % to 3.8 wt. % carbon, 2.2 wt. % to 3.2 wt. % silicon, 0.5 wt. % to 1.3 wt. % copper, and at least 75.0 wt. % iron, based on the total weight of the cast iron. The cast iron further includes 0.01 wt. % to 0.5 wt. % manganese, 0.01 wt. % to 0.2 wt. % chromium, up to 0.3 wt. % phosphorous, up to 0.05 wt. % sulfur, up to 0.2 wt. % tin, and up to 0.1 wt. % magnesium, based on the total weight of the cast iron. Preferably, the cast iron is free of molybdenum, nickel, and vanadium. The cast iron is also heat treated and solidifies to achieve fully spheroidal graphite.

This spheroidal graphite or flake graphite cast-iron alloy in weight % comprises the following elements: Carbon (C) between 1.2% and 3.5%, Silicon (Si) between 1.0% or 1.2% and 3%, Nickel (Ni) between 26% and 31%, Cobalt (Co) between 15% and 20%, the remainder being Iron and inevitable impurities.

Application to the production of tooling.

This spheroidal graphite or flake graphite cast-iron alloy in weight % comprises the following elements: Carbon (C) between 1.2% and 3.5%, Silicon (Si) between 1.0% or 1.2% and 3%, Nickel (Ni) between 26% and 31%, Cobalt (Co) between 15% and 20%, the remainder being Iron and inevitable impurities.

Application to the production of tooling.

A centrifugally cast composite roll for hot rolling comprising an outer layer having a composition comprising by mass 0.8-3.5% of C, 0.1-2.5% of Si, 0.1-2.5% of Mn, 1.2-15% of Cr, 1-5% of Ni, and 1-10% of Mo+0.5×W, the balance being substantially Fe and inevitable impurities, and an inner layer made of an iron-based alloy and integrally fused to the outer layer; the outer layer having Shore hardness of 67-82 at the initial diameter of the composite roll; and the maximum Shore hardness of the outer layer in a range 30 mm or more deep from the initial diameter being higher by 1 or more than the Shore hardness of the outer layer at the initial diameter.

A centrifugally cast composite roll for hot rolling comprising an outer layer having a composition comprising by mass 0.8-3.5% of C, 0.1-2.5% of Si, 0.1-2.5% of Mn, 1.2-15% of Cr, 1-5% of Ni, and 1-10% of Mo+0.5×W, the balance being substantially Fe and inevitable impurities, and an inner layer made of an iron-based alloy and integrally fused to the outer layer; the outer layer having Shore hardness of 67-82 at the initial diameter of the composite roll; and the maximum Shore hardness of the outer layer in a range 30 mm or more deep from the initial diameter being higher by 1 or more than the Shore hardness of the outer layer at the initial diameter.