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.

A novel briquetting roll having excellent performance such as providing both abrasion resistance and spalling resistance, which can also be manufactured at low cost and in a short period of time, and a method for manufacturing the same, are provided wherein the briquetting roll 1 integrally has an inner layer material 4 and an outer layer material 5, which comprise mutually different materials and are in contact with each other at the respective exterior and interior thereof, and has pockets 6 formed at the outer circumference of the outer layer material 5. A chromium-molybdenum forged steel material is used for the inner layer material 4 and a high-carbon high-speed steel material is used for the outer layer material 5. The outer layer material 5 may be formed on the outside of the inner layer material 4 by a continuous pouring process.

A novel briquetting roll having excellent performance such as providing both abrasion resistance and spalling resistance, which can also be manufactured at low cost and in a short period of time, and a method for manufacturing the same, are provided wherein the briquetting roll 1 integrally has an inner layer material 4 and an outer layer material 5, which comprise mutually different materials and are in contact with each other at the respective exterior and interior thereof, and has pockets 6 formed at the outer circumference of the outer layer material 5. A chromium-molybdenum forged steel material is used for the inner layer material 4 and a high-carbon high-speed steel material is used for the outer layer material 5. The outer layer material 5 may be formed on the outside of the inner layer material 4 by a continuous pouring process.

A martensitic alloy component includes by weight, 0.25% to 0.31% carbon (C), 2.1% to 3.0% manganese (Mn), 0.22% to 0.28% silicon (Si), 2.0% to 2.2% chromium (Cr), 0.45% to 0.55% molybdenum (Mo), 0.08% to 0.12% vanadium (V), and the balance is iron (Fe) and incidental impurities. The manganese-chromium martensitic alloy component has a hardenability corresponding to an ideal diameter of about 15 inches to about 30 inches or more.

The present invention provides an outer layer material for a composite roll for rolling, in which the strength of secondary eutectic carbides can be increased by reducing a B amount in the secondary eutectic carbides and surface roughening resistance can be improved, and a composite roll for rolling in which this outer layer material is used in an outer layer. The outer layer material for a composite roll for rolling of the present invention is an outer layer material for a composite roll for rolling containing C in an amount of 1.8 mass % or more and 2.5 mass % or less, Si in an amount of more than 0 mass % and 1.0 mass % or less, Mn in an amount of more than 0 mass % and 1.0 mass % or less, Ni in an amount of more than 0 mass % and 0.5 mass % or less, Cr in an amount of more than 3.0 mass % and 8.0 mass % or less, Mo in an amount of more than 2.0 mass % and 10.0 mass % or less, W in an amount of more than 0 mass % and 10.0 mass % or less, V in an amount of more than 0 mass % and 10.0 mass % or less, and B in an amount of more than 0 mass % and less than 0.01 mass %, and a remaining portion including Fe and inevitable impurities.

The present invention provides an outer layer material for a composite roll for rolling, in which the strength of secondary eutectic carbides can be increased by reducing a B amount in the secondary eutectic carbides and surface roughening resistance can be improved, and a composite roll for rolling in which this outer layer material is used in an outer layer. The outer layer material for a composite roll for rolling of the present invention is an outer layer material for a composite roll for rolling containing C in an amount of 1.8 mass % or more and 2.5 mass % or less, Si in an amount of more than 0 mass % and 1.0 mass % or less, Mn in an amount of more than 0 mass % and 1.0 mass % or less, Ni in an amount of more than 0 mass % and 0.5 mass % or less, Cr in an amount of more than 3.0 mass % and 8.0 mass % or less, Mo in an amount of more than 2.0 mass % and 10.0 mass % or less, W in an amount of more than 0 mass % and 10.0 mass % or less, V in an amount of more than 0 mass % and 10.0 mass % or less, and B in an amount of more than 0 mass % and less than 0.01 mass %, and a remaining portion including Fe and inevitable impurities.

When a rod-shaped workpiece (W) having an outer peripheral surface with a circular cross section is inductively heated to a quenching temperature while being conveyed at a predetermined velocity along an axial direction of the rod-shaped workpiece (W), the rod-shaped workpiece (W) being currently conveyed is heated to a predetermined temperature equal to or lower than the quenching temperature by a first heating coil (2A), which is electrically connected to a first high-frequency power supply (3) and has a constant output. Then, the rod-shaped workpiece (W) being currently conveyed is heated so as to be maintained at the quenching temperature by a second heating coil (2B), which is electrically connected to a second high-frequency power supply (4) and has a constant output.

Provided is an induction heating apparatus including a conveying device, which is configured to convey a rotatable workpiece along a linear guiding conveyance path, and a heating coil, which is configured to inductively heat the workpiece being conveyed along the guiding conveyance path. The conveying device includes a first shaft member and a second shaft member, which are arranged in parallel so as to be separated from each other, and a rotary mechanism, which is configured to rotationally drive at least one of the first shaft member and the second shaft member about an axis thereof. The second shaft member is formed of a threaded shaft having a helical convex portion formed along an outer periphery of the second shaft member. The guiding conveyance path is formed by a groove bottom surface of a helical groove defined on the second shaft member by the helical convex portion.

A rolling bearing includes a plurality of balls and two raceway members. The balls and the raceway members have contact surfaces. In at least either of balls and raceway members, a superficial part is formed in a region from the contact surface to a depth of 20 ?m. Of the balls and the raceway members, the member in which a superficial part is formed in the contact surface is made of steel that has been quenched. A raceway surface which is a contact surface of the raceway member is a partial arc in a sectional view that passes a central axis of the rolling bearing and is parallel with the central axis. The diameter of the partial arc is greater than or equal to 1.01 times and less than or equal to 1.08 times the diameter of the ball.