A bearing part according to one embodiment of the present invention is a bearing part composed of a chromium molybdenum steel, the bearing part including a diffusion layer in a surface of the bearing part. The diffusion layer includes a plurality of compound grains and a plurality of martensite blocks. An average grain size of the compound grains is less than or equal to 0.3 m. An area ratio of the compound grains in the diffusion layer is more than or equal to 3%. A maximum grain size of the plurality of martensite blocks is less than or equal to 3.8 m.

A bearing part according to one embodiment of the present invention is a bearing part composed of a chromium molybdenum steel, the bearing part including a diffusion layer in a surface of the bearing part. The diffusion layer includes a plurality of compound grains and a plurality of martensite blocks. An average grain size of the compound grains is less than or equal to 0.3 m. An area ratio of the compound grains in the diffusion layer is more than or equal to 3%. A maximum grain size of the plurality of martensite blocks is less than or equal to 3.8 m.

A method of forming a component includes heating the component to a burnishing temperature above 500 degrees Fahrenheit, and burnishing a surface of the component while the component is at the burnishing temperature to densify the surface. The burnishing process at an elevated temperature may be integrated into other processes, such as the sintering or heat treating processes.

A method of forming a component includes heating the component to a burnishing temperature above 500 degrees Fahrenheit, and burnishing a surface of the component while the component is at the burnishing temperature to densify the surface. The burnishing process at an elevated temperature may be integrated into other processes, such as the sintering or heat treating processes.

An apparatus for imparting compressive residual stress to at least a surface portion of a first plurality of balls includes a first body having a first surface, the first surface including a smooth contact portion, the smooth contact portion being substantially flat or convex and having a surface hardness greater than or equal to the initial surface hardness of the balls. The apparatus also includes a second body having a second surface, the first surface overlying the second surface, and at least one drive operably connected to the first body or to the second body and configured to move one of the first and second bodies relative to the other body at a substantially fixed distance, the at least one drive also being configured to move the first body toward the second body with a force or to move the second body toward the first body with the force.

A method of imparting compressive residual stress to a first plurality of balls includes a) placing the balls between a first body having a first surface and a second body having a second surface, the first surface including a smooth contact portion, the smooth contact portion being substantially flat or convex and having a surface hardness greater than or equal to an initial surface hardness of the balls, b) imparting a compressive stress along a first diameter of the balls by pressing the first body toward the second body or the second body toward the first body or the first and second bodies toward one another with a force, and c) causing relative movement between the first surface and the second surface while maintaining the force at or above a minimum level to impart the compressive stress along other diameters of the balls different than the first diameter.

A method of forming a component includes heating the component to a burnishing temperature above 500 degrees Fahrenheit, and burnishing a surface of the component while the component is at the burnishing temperature to densify the surface. The burnishing process at an elevated temperature may be integrated into other processes, such as the sintering or heat treating processes.

A method for surface hardening at least one part of a surface of a metal component is provided. The steps include a) enriching the at least one part of a surface of a metal component with at least one of carbon and nitrogen, and b) induction hardening the at least one part of the surface of the metal component.

A method for surface hardening at least one part of a surface of a metal component is provided. The steps include a) enriching the at least one part of a surface of a metal component with at least one of carbon and nitrogen, and b) induction hardening the at least one part of the surface of the metal component.

The invention refers to the manufacturing of ball-shaped metal products. The method consists in through heating of round billets made in appropriate size in a mid-frequency induction unit, rolling such billets into balls in a cross rolling mill at 950 C.-1070 C., cooling the balls down to 620 C.-700 C. in a cooling drum with forced air cooling, heating the surface of the balls up to 850 C.-930 C. in a high-frequency induction unit containing a rotating transport tube and multiple inductor sections, quenching the balls to 125 C.-160 C. in a quenching drum where they are cooled by running water, and allowing the balls to self-temper in the containers. The method enables better wear and impact resistance of metal balls when they are made of low-alloy steels, thereby allowing to reduce the carbon mass fraction of the used steel.