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.

A heat treatment method of manufacturing high carbon bearing steel having excellent abrasion resistance and fatigue resistance, a steel wire rod for high carbon bearing steel subjected to the heat treatment, a manufacturing method of the steel wire rod, high carbon bearing steel manufactured by the heat treatment and a soaking method of a steel bloom used for manufacturing the steel wire rod. The heat treatment method of bearings includes the steps of: quenching a bearing-shaped steel part containing, by weight, 0.5% to 1.20% carbon and 1.0% to 2.0% silicon; and partitioning the quenched steel part at a temperature ranging from M.sub.s100 C. to M.sub.s for at least 10 minutes, where M.sub.s represents a temperature at which formation of martensite will start.

A heat treatment method of manufacturing high carbon bearing steel having excellent abrasion resistance and fatigue resistance, a steel wire rod for high carbon bearing steel subjected to the heat treatment, a manufacturing method of the steel wire rod, high carbon bearing steel manufactured by the heat treatment and a soaking method of a steel bloom used for manufacturing the steel wire rod. The heat treatment method of bearings includes the steps of: quenching a bearing-shaped steel part containing, by weight, 0.5% to 1.20% carbon and 1.0% to 2.0% silicon; and partitioning the quenched steel part at a temperature ranging from M.sub.s100 C. to M.sub.s for at least 10 minutes, where M.sub.s represents a temperature at which formation of martensite will start.

A surface layer material of a hot rolling mill roll is provided. The surface layer has a chemical composition containing, by mass %, C: 2.4% or more and 3.5% or less, Si: 1.2% or more and 2.4% or less, Mn: 0.2% or more and 2.0% or less, Cr: 0.8% or more and 2.1% or less, Mo: 0.3% or more and 1.1% or less, Ni: 3.0% or more and 6.0% or less, V: 1.0% or more and 2.2% or less, Nb: 0.1% or more and 0.5% or less, REM: 0.0005%) or more and 0.1% or less, Al: 0.003% or more and 0.05% or less, and the balance being Fe and inevitable impurities. The contents of C, Cr, V, Nb, REM, and Al satisfy the relationships Cr+0.2C(0.24V+0.13Nb)3.0 and 0.01REM/Al3.2.

A method for cost effectively case hardening a component formed from a martensitic stainless steel material with a desired metallurgical condition for high temperature, high rolling contact fatigue, corrosion and spall initiation and propagation resistance bearing performance. The method describes a method to significantly reduce the carburization or carbo-nitriding process times for appreciable reduction in manufacturing cost. The Method includes the steps of: forming the component from a martensitic stainless steel material having an ASTM grain size of 9 or finer; and subjecting the component to one of a carburization and a carbo-nitriding treatment with significantly lower case hardening times for manufacturing cost-effectiveness.

A method for cost effectively case hardening a component formed from a martensitic stainless steel material with a desired metallurgical condition for high temperature, high rolling contact fatigue, corrosion and spall initiation and propagation resistance bearing performance. The method describes a method to significantly reduce the carburization or carbo-nitriding process times for appreciable reduction in manufacturing cost. The Method includes the steps of: forming the component from a martensitic stainless steel material having an ASTM grain size of 9 or finer; and subjecting the component to one of a carburization and a carbo-nitriding treatment with significantly lower case hardening times for manufacturing cost-effectiveness.

The present disclosure includes a differential heat treatment method for a forming roller including an outer circumferential surface heat treatment step for heating the outer circumferential surfaces of roller units. The method may additionally include a first natural cooling step for naturally cooling until the surface temperature reaches 100-150 C., an inner circumferential surface heat treatment step for heating the inner circumferential surfaces of the roller units. The method may additionally include a second cooling step for naturally cooling until the roller units reach a room temperature state after the inner circumferential heat treatment. Further, the method may include an inspection and release step for inspecting the hardness of the outer circumferential surface and the inner circumferential surface after the second cooling and releasing when the hardness is within an error range.

The present disclosure includes a differential heat treatment method for a forming roller including an outer circumferential surface heat treatment step for heating the outer circumferential surfaces of roller units. The method may additionally include a first natural cooling step for naturally cooling until the surface temperature reaches 100-150 C., an inner circumferential surface heat treatment step for heating the inner circumferential surfaces of the roller units. The method may additionally include a second cooling step for naturally cooling until the roller units reach a room temperature state after the inner circumferential heat treatment. Further, the method may include an inspection and release step for inspecting the hardness of the outer circumferential surface and the inner circumferential surface after the second cooling and releasing when the hardness is within an error range.

The present disclosure includes a differential heat treatment method for a forming roller including an outer circumferential surface heat treatment step for heating the outer circumferential surfaces of roller units. The method may additionally include a first natural cooling step for naturally cooling until the surface temperature reaches 100-150 C., an inner circumferential surface heat treatment step for heating the inner circumferential surfaces of the roller units. The method may additionally include a second cooling step for naturally cooling until the roller units reach a room temperature state after the inner circumferential heat treatment. Further, the method may include an inspection and release step for inspecting the hardness of the outer circumferential surface and the inner circumferential surface after the second cooling and releasing when the hardness is within an error range.