Provided is a gas nitrocarburizing method forming a nitride layer in a surface layer portion of a workpiece made of steel by heating the workpiece within a heat treatment furnace into which a heat treatment gas is introduced, the heat treatment gas containing ammonia gas and at least one of carbon dioxide gas and hydrogen gas, and having a remainder formed of an impurity.

Provided is a gas nitrocarburizing method forming a nitride layer in a surface layer portion of a workpiece made of steel by heating the workpiece within a heat treatment furnace into which a heat treatment gas is introduced, the heat treatment gas containing ammonia gas and at least one of carbon dioxide gas and hydrogen gas, and having a remainder formed of an impurity.

An outer ring, an inner ring, and a ball each serving as a bearing part is made of a steel containing 0.95 mass % or more and 1.10 mass % or less of carbon, 0.05 mass % or more and less than 0.3 mass % of silicon, 0.10 mass % or more and 0.50 mass % or less of manganese, and 1.30 mass % or more and 2.00 mass % or less of chromium, with the rest made up of iron and an impurity. A surface layer region defined as a region extending to a depth of not more than 20 m from an outer ring raceway surface, an inner ring raceway surface, and a ball rolling surface, which are each a surface where the bearing part is in rolling contact with another part, has an average nitrogen concentration of 0.2 mass % or more and 0.7 mass % or less. Five or more carbides with a diameter of 0.5 m or less are present per 100 m.sup.2 in the surface layer region.

An outer ring, an inner ring, and a ball each serving as a bearing part is made of a steel containing 0.95 mass % or more and 1.10 mass % or less of carbon, 0.05 mass % or more and less than 0.3 mass % of silicon, 0.10 mass % or more and 0.50 mass % or less of manganese, and 1.30 mass % or more and 2.00 mass % or less of chromium, with the rest made up of iron and an impurity. A surface layer region defined as a region extending to a depth of not more than 20 m from an outer ring raceway surface, an inner ring raceway surface, and a ball rolling surface, which are each a surface where the bearing part is in rolling contact with another part, has an average nitrogen concentration of 0.2 mass % or more and 0.7 mass % or less. Five or more carbides with a diameter of 0.5 m or less are present per 100 m.sup.2 in the surface layer region.

Provided is a forged steel roll for cold rolling with a Vickers hardness Hy at 400? C. of 400 or more.

Provided is a forged steel roll for cold rolling with a Vickers hardness Hy at 400? C. of 400 or more.

A method of forming a component from a powder metal includes forming the component to a desired shape from the powder metal, heating the component to a burnishing temperature of 900 to 1300 degrees Fahrenheit, and burnishing a surface of the component while the component is at the burnishing temperature to densify the surface.

This steel material for bearings includes prescribed components in the steel, the oxide inclusions in the steel that have a minor axis of 1 m or greater satisfying the following conditions (1) and (2). (1) The average composition contains specific respective amounts of CaO, Al.sub.2O.sub.3, SiO.sub.2, and TiO.sub.2, and CaO+Al.sub.2O.sub.3+SiO.sub.2+TiO.sub.260%. (2) The proportion of oxide inclusions in which TiN occurs at the interface of the oxide inclusions and the steel is 30% or more of the total of the oxide inclusions.

A rolling component has a surface and is made of steel. The rolling component comprises a surface layer portion that is a region up to 20 m in depth from the surface. The rolling component is intended for use with hydrogen-utilizing equipment. The steel contains 0.70 mass percent or more and 1.10 mass percent or less of carbon, 0.15 mass percent or more and 0.35 mass percent or less of silicon, 0.30 mass percent or more and 0.60 mass percent or less of manganese, 1.30 mass percent or more and 1.60 mass percent or less of chromium, 0.01 mass percent or more and 0.50 mass percent or less of molybdenum, and 0.01 mass percent or more and 0.50 mass percent or less of vanadium, with a balance consisting of iron and unavoidable impurities. In the surface layer portion, the steel has a nitrogen concentration of 0.2 mass percent or more.

A rolling component has a surface and is made of steel. The rolling component comprises a surface layer portion that is a region up to 20 m in depth from the surface. The rolling component is intended for use with hydrogen-utilizing equipment. The steel contains 0.70 mass percent or more and 1.10 mass percent or less of carbon, 0.15 mass percent or more and 0.35 mass percent or less of silicon, 0.30 mass percent or more and 0.60 mass percent or less of manganese, 1.30 mass percent or more and 1.60 mass percent or less of chromium, 0.01 mass percent or more and 0.50 mass percent or less of molybdenum, and 0.01 mass percent or more and 0.50 mass percent or less of vanadium, with a balance consisting of iron and unavoidable impurities. In the surface layer portion, the steel has a nitrogen concentration of 0.2 mass percent or more.