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.

A steel ball for use as grinding media in a mill, and a method of fabricating such ball are disclosed. The steel ball has the following composition, by weight

TABLE-US-00001 Carbon 1.05% 0.05 Silicon 0.55% 0.45 Manganese 0.75% 0.60 Chromium 0.90% 0.60 Molybdenum 0.20% 0.20 Phosphorous 0.15% 0.15 Sulphur 0.015% 0.015 Nickel 0.225% 0.225 Copper 0.225% 0.225 Vanadium 0.05% 0.05 Aluminium 0.05% 0.05
with the balance being iron. The ball has an average surface hardness of 60-65 HRC and an average volumetric hardness of 59-65 HRC. The ball has a tempered martensitic microstructure and is formed by heating a billet, forging the billet to form a substantially spherical ball, quenching and then tempering the ball.

A steel ball for use as grinding media in a mill, and a method of fabricating such ball are disclosed. The steel ball has the following composition, by weight

TABLE-US-00001 Carbon 1.05% 0.05 Silicon 0.55% 0.45 Manganese 0.75% 0.60 Chromium 0.90% 0.60 Molybdenum 0.20% 0.20 Phosphorous 0.15% 0.15 Sulphur 0.015% 0.015 Nickel 0.225% 0.225 Copper 0.225% 0.225 Vanadium 0.05% 0.05 Aluminium 0.05% 0.05
with the balance being iron. The ball has an average surface hardness of 60-65 HRC and an average volumetric hardness of 59-65 HRC. The ball has a tempered martensitic microstructure and is formed by heating a billet, forging the billet to form a substantially spherical ball, quenching and then tempering the ball.

The present invention provides a method of heat treating a steel component including the sequential steps of: (a) carbonitriding the steel component; (b) quenching the steel component; (c) optionally tempering the steel component; and (d) ferritically nitrocarburizing the steel component.

The present invention provides a method of heat treating a steel component including the sequential steps of: (a) carbonitriding the steel component; (b) quenching the steel component; (c) optionally tempering the steel component; and (d) ferritically nitrocarburizing the steel component.

A method for producing a rolling bearing component includes providing a rolling bearing component formed from a rolling bearing steel, heating the rolling bearing component to form an austenitic microstructure, and cooling the rolling bearing component in a warm salt bath to a temperature below a martensite start temperature of the rolling bearing steel. The rolling bearing component has a wall thickness or a diameter of at least 85 mm at at least one point and includes a martensitic microstructure in an edge layer region and a microstructure consisting of pearlite or upper bainite in a core region after the cooling. A rolling bearing component produced by the method and a rolling bearing comprising the rolling bearing component are also disclosed.

A method for producing a rolling bearing component includes providing a rolling bearing component formed from a rolling bearing steel, heating the rolling bearing component to form an austenitic microstructure, and cooling the rolling bearing component in a warm salt bath to a temperature below a martensite start temperature of the rolling bearing steel. The rolling bearing component has a wall thickness or a diameter of at least 85 mm at at least one point and includes a martensitic microstructure in an edge layer region and a microstructure consisting of pearlite or upper bainite in a core region after the cooling. A rolling bearing component produced by the method and a rolling bearing comprising the rolling bearing component are also disclosed.

There are provided a rolling bearing and a rolling element production method, which can improve a flacking life. A rolling bearing includes an inner ring (2), an outer ring (3), and a rolling element (4). The rolling element (4) has a hardness of HRC61.1 or higher and a residual austenite content of 31 volt or less, and a ratio of a hardness of the rolling element (4) to a hardness of the inner ring (2) and the outer ring (3) is 1 or higher.

There are provided a rolling bearing and a rolling element production method, which can improve a flacking life. A rolling bearing includes an inner ring (2), an outer ring (3), and a rolling element (4). The rolling element (4) has a hardness of HRC61.1 or higher and a residual austenite content of 31 volt or less, and a ratio of a hardness of the rolling element (4) to a hardness of the inner ring (2) and the outer ring (3) is 1 or higher.