An austenitic cast iron including basic elements of C, Si, Cr, Ni, Mn and Cu; and the balance including Fe, inevitable impurities and/or a trace-amount modifier element, which is effective in improving a characteristic of the cast iron, in a trace amount; and structured by a base comprising an Fe alloy in which an austenite phase makes a major phase in ordinary-temperature region; wherein the basic elements fall within compositional ranges that satisfy the following conditions when the entirety of the cast iron is taken as 100% by mass: C: from 2.0 to 3.0%; Si: from 4.0 to 5.4%; Cr: from 0.8 to 2.0%; Mn: from 3.9 to 5.6%; Ni: from 17 to 22%; and Cu: from 0.9 to 1.6%.

An austenitic cast iron including basic elements of C, Si, Cr, Ni, Mn and Cu; and the balance including Fe, inevitable impurities and/or a trace-amount modifier element, which is effective in improving a characteristic of the cast iron, in a trace amount; and structured by a base comprising an Fe alloy in which an austenite phase makes a major phase in ordinary-temperature region; wherein the basic elements fall within compositional ranges that satisfy the following conditions when the entirety of the cast iron is taken as 100% by mass: C: from 2.0 to 3.0%; Si: from 4.0 to 5.4%; Cr: from 0.8 to 2.0%; Mn: from 3.9 to 5.6%; Ni: from 17 to 22%; and Cu: from 0.9 to 1.6%.

The disclosure relates to a lubrication-free piece having a friction surface that rubs against a second surface, the lubrication-free piece having at least one structure made from spheroidal graphite cast iron or steel, the external surface of the piece including at least one layer of lubricating thermoplastic polymers, wherein the lubrication-free piece includes a nickel/aluminium-based intermediary layer between the spheroidal graphite cast iron or steel structure and the layer of lubricating thermoplastic polymers.

The disclosure relates to a lubrication-free piece having a friction surface that rubs against a second surface, the lubrication-free piece having at least one structure made from spheroidal graphite cast iron or steel, the external surface of the piece including at least one layer of lubricating thermoplastic polymers, wherein the lubrication-free piece includes a nickel/aluminium-based intermediary layer between the spheroidal graphite cast iron or steel structure and the layer of lubricating thermoplastic polymers.

A method for producing spheroidal graphite cast iron having a specific final composition includes: subjecting a molten iron to a spheroidization treatment using a spheroidizing agent of an FeSiMgCa-based alloy containing no rare earth element; conducting an inoculation treatment using a first FeSi-based inoculant; and conducting a pouring inoculation treatment with a given amount of a second FeSi-based inoculant containing 45-75% of Si, 1-3% of Ca, and 15 ppm or less of Ba.

A method for producing spheroidal graphite cast iron having a specific final composition includes: subjecting a molten iron to a spheroidization treatment using a spheroidizing agent of an FeSiMgCa-based alloy containing no rare earth element; conducting an inoculation treatment using a first FeSi-based inoculant; and conducting a pouring inoculation treatment with a given amount of a second FeSi-based inoculant containing 45-75% of Si, 1-3% of Ca, and 15 ppm or less of Ba.

A grade of ductile cast iron having a tensile strength (Rm) equal to or greater than 700 MPa, an elongation at break equal to or greater than 11%, a yield strength (Rp.sub.0.2) equal to or greater than 532 MPa, and a minimum ratio of yield strength (Rp.sub.0.2) to tensile strength (Rm) of 76% in a tensile test performed on a specimen taken from a tensile bar in accordance with standard EN 1563 and having a diameter of 25 mm and a length of 200 mm.

A grade of ductile cast iron having a tensile strength (Rm) equal to or greater than 700 MPa, an elongation at break equal to or greater than 11%, a yield strength (Rp.sub.0.2) equal to or greater than 532 MPa, and a minimum ratio of yield strength (Rp.sub.0.2) to tensile strength (Rm) of 76% in a tensile test performed on a specimen taken from a tensile bar in accordance with standard EN 1563 and having a diameter of 25 mm and a length of 200 mm.

A spheroidal graphite cast iron for a component of an engine exhaust system includes carbon ranging from about 3.0 wt % to about 3.4 wt %, silicon ranging from about 4.2 wt % to about 4.5 wt %, manganese ranging from about 0.1 wt % to about 0.3 wt %, sulfur ranging from about 0.002 wt % to about 0.01 wt %, phosphorous in a range equal to or less than about 0.05 wt %, magnesium ranging from about 0.035 wt % to about 0.055 wt %, molybdenum ranging from about 0.9 wt % to about 1.2 wt %, nickel ranging from about 0.2 wt % to about 0.5 wt %, vanadium ranging from about 0.4 wt % to about 0.6 wt %, niobium ranging from about 0.1 wt % to about 0.4 wt %, cerium ranging from about 0.005 wt % to about 0.01 wt %, aluminum ranging from about 0.003 wt % to about 0.007 wt %, and a remainder of iron.

A spheroidal graphite cast iron for a component of an engine exhaust system includes carbon ranging from about 3.0 wt % to about 3.4 wt %, silicon ranging from about 4.2 wt % to about 4.5 wt %, manganese ranging from about 0.1 wt % to about 0.3 wt %, sulfur ranging from about 0.002 wt % to about 0.01 wt %, phosphorous in a range equal to or less than about 0.05 wt %, magnesium ranging from about 0.035 wt % to about 0.055 wt %, molybdenum ranging from about 0.9 wt % to about 1.2 wt %, nickel ranging from about 0.2 wt % to about 0.5 wt %, vanadium ranging from about 0.4 wt % to about 0.6 wt %, niobium ranging from about 0.1 wt % to about 0.4 wt %, cerium ranging from about 0.005 wt % to about 0.01 wt %, aluminum ranging from about 0.003 wt % to about 0.007 wt %, and a remainder of iron.