The present invention refers to a vermicular cast iron alloy specially designed for blocks and heads of internal combustion engines that have special requirements for mechanical strength and machinability; said vermicular alloy has a microstructure that results in high values of mechanical properties, such as a minimum strength limit of 500 Mpa, a minimum yield limit of 350 MPa, along with good machinability; also, wherein the ferritization factor must be such that it is between 3.88 and 5.48. This set of properties makes it possible to design new engine blocks and heads with complex geometry, high mechanical properties, without compromising machinability, making it attractive both from a technical and economic point of view.

The present invention refers to a vermicular cast iron alloy specially designed for blocks and heads of internal combustion engines that have special requirements for mechanical strength and machinability; said vermicular alloy has a microstructure that results in high values of mechanical properties, such as a minimum strength limit of 500 Mpa, a minimum yield limit of 350 MPa, along with good machinability; also, wherein the ferritization factor must be such that it is between 3.88 and 5.48. This set of properties makes it possible to design new engine blocks and heads with complex geometry, high mechanical properties, without compromising machinability, making it attractive both from a technical and economic point of view.

A spheroidal graphite cast iron meeting N.sub.(5-)≥250, N.sub.(5-20)/N.sub.(5-)≥0.6, and N.sub.(30-)/N.sub.(5-)≤0.2, wherein N.sub.(5-) represents the number (/mm.sup.2) of graphite particles having equivalent-circle diameters of 5 μm or more, N.sub.(5-20) represents the number (/mm.sup.2) of graphite particles having equivalent-circle diameters of 5 μm or more and less than 20 μm, and N.sub.(30-) represents the number (/mm.sup.2) of graphite particles having equivalent-circle diameters of 30 μm or more, among graphite particles observed in an arbitrary cross section of at least 1 mm.sup.2.

A spheroidal graphite cast iron meeting N.sub.(5-)≥250, N.sub.(5-20)/N.sub.(5-)≥0.6, and N.sub.(30-)/N.sub.(5-)≤0.2, wherein N.sub.(5-) represents the number (/mm.sup.2) of graphite particles having equivalent-circle diameters of 5 μm or more, N.sub.(5-20) represents the number (/mm.sup.2) of graphite particles having equivalent-circle diameters of 5 μm or more and less than 20 μm, and N.sub.(30-) represents the number (/mm.sup.2) of graphite particles having equivalent-circle diameters of 30 μm or more, among graphite particles observed in an arbitrary cross section of at least 1 mm.sup.2.

Embodiments of an alloy that can be resistant to cracking. In some embodiments, the alloy can be advantageous for use as a hardfacing alloys, in both a diluted and undiluted state. Certain microstructural, thermodynamic, and performance criteria can be met by embodiments of the alloys that may make them advantageous for hardfacing.

Embodiments of an alloy that can be resistant to cracking. In some embodiments, the alloy can be advantageous for use as a hardfacing alloys, in both a diluted and undiluted state. Certain microstructural, thermodynamic, and performance criteria can be met by embodiments of the alloys that may make them advantageous for hardfacing.

Embodiments of an alloy that can be resistant to cracking. In some embodiments, the alloy can be advantageous for use as a hardfacing alloys, in both a diluted and undiluted state. Certain microstructural, thermodynamic, and performance criteria can be met by embodiments of the alloys that may make them advantageous for hardfacing.

Bearing bushings which are exposed to highly elevated temperatures during operation, corresponding high-temperature-resistant bearing bushings and exhaust-gas turbochargers having at least one such bearing bushing, include an iron material having a material composition which, apart from iron, has at least carbon, silicon, manganese, nickel, chromium, molybdenum and tungsten alloy constituents in certain amounts. This material composition ensures sufficient temperature resistance and self-lubricating properties with simultaneously good machining properties and a moderate price.

Bearing bushings which are exposed to highly elevated temperatures during operation, corresponding high-temperature-resistant bearing bushings and exhaust-gas turbochargers having at least one such bearing bushing, include an iron material having a material composition which, apart from iron, has at least carbon, silicon, manganese, nickel, chromium, molybdenum and tungsten alloy constituents in certain amounts. This material composition ensures sufficient temperature resistance and self-lubricating properties with simultaneously good machining properties and a moderate price.

A self-lubricating rolling bearing is provided. The chemical compositions in the inner rings and the outer rings of bearing are 3.4-3.7% C, 2.7-2.9% Si, 0.3-0.5% Mn, 0.3-0.5% Cr, ≤0.05% S, ≤0.05% P, 0.03-0.045% Residual Mg, and the remainder Fe. The total percent of the chemical compositions is 100%. The material for the inner and outer rings of the rolling bearing introduced in the invention is austempered ductile iron (ADI). In the microstructure of ADI, the diameter of the graphite nodules is less than 0.02 mm, the number of graphite spheres per square millimeter is more than 400, and the microstructure of the metal matrix in the ADI can be showed clearly only when it is observed on the microscope with a magnification more than 500. Eventually, the self-lubricating rolling bearings are made from the ADI.