Abstract: Provided is a method for executing a quenching method in which an object to be treated that is a quenching target is cooled with a quenching coolant that is a coolant for quenching, in which the object to be treated is moved inside the quenching coolant accumulated in a cooling tank, by a moving device for moving the object to be treated, and at least from when the object to be treated comes into contact with the quenching coolant until a surface of the object to be treated undergoes martensitic transformation, a state in which a relative speed of the object to be treated and the quenching coolant is slower than a moving speed of the object to be treated is maintained.

Abstract: In this steel component, the concentration of C in a surface layer is 0.85 mass % or more to 1.2 mass % or less, which is higher than the concentration of C in a starting material steel, the surface layer has a volume ratio of a retained-austenite structure higher than 0% and lower than 10%, the remainder of the surface layer is a martensitic structure, the area fraction of grain boundary carbides in the surface layer is lower than 2%, a layer inside the surface layer is higher than the surface layer in a volume ratio of a retained-austenite structure, and in the layer inside the surface layer, the remainder is a martensitic structure.

Abstract: In this steel component, the concentration of C in a surface layer is 0.85 mass % or more to 1.2 mass % or less, which is higher than the concentration of C in a starting material steel, the surface layer has a volume ratio of a retained-austenite structure higher than 0% and lower than 10%, the remainder of the surface layer is a martensitic structure, the area fraction of grain boundary carbides in the surface layer is lower than 2%, a layer inside the surface layer is higher than the surface layer in a volume ratio of a retained-austenite structure, and in the layer inside the surface layer, the remainder is a martensitic structure.

Abstract: A steel gear 1 includes a generally cylindrical outer peripheral ring portion 2, on an outer peripheral surface 20a of which a toothed shape 10 is formed, and a flange portion 3 provided to extend radially inward from an inner peripheral surface 20b of the outer peripheral ring portion 2. The outer peripheral ring portion 2 includes a first projecting portion 21 that projects toward one side in the axial direction with respect to a coupling position at which the first projecting portion 21 is coupled to the flange portion 3, and a second projecting portion 22 that projects toward the other side in the axial direction with respect to a coupling position at which the second projecting portion 22 is coupled to the flange portion 3. The axial length of the first projecting portion 21 is longer than the axial length of the second projecting portion 22.

Abstract: A steel gear includes a substantially cylindrical outer peripheral ring portion having a toothed shape formed on its outer peripheral surface; and a flange portion extended radially inward from an inner peripheral surface of the outer peripheral ring portion. The steel gear has a thermal history layer formed in the outer peripheral ring portion, and the depth of the thermal history layer in the direction inward from the tooth bottom of the toothed shape of the outer peripheral surface is greater in the first protruding portion and the second protruding portion than in the coupling portion with the flange portion, and is substantially the same between the first protruding portion and the second protruding portion. As a result, even if the “carburization/slow cooling/high-frequency quenching treatment” is used as a manufacturing method of the steel gear, the steel gear has high dimensional accuracy.

Abstract: A drive plate includes a disk-shaped plate portion; and a tooth-shaped portion formed at an outer peripheral end of the plate portion. The plate portion and the tooth-shaped portion are integrally shaped from a single steel plate material. The plate portion and the tooth-shaped portion include a carburized layer provided over an entire surface layer of the plate portion and the tooth-shaped portion, the carburized layer having a carbon concentration higher than that of a center portion of the plate portion and the tooth-shaped portion in a thickness direction. The carburized layer of the plate portion is higher in hardness than the center portion of the plate portion in the thickness direction. The carburized layer of the tooth-shaped portion has been subjected to a quenching process, and is further higher in hardness than the carburized layer of the plate portion.

Abstract: A manufacturing method for a composite steel part including manufacturing a first steel part by preparing an intermediate product in which an extra portion is added, and heating the intermediate product to an austenitizing temperature in a carburizing atmosphere to form a carburized layer, cooling the intermediate product at a rate less than a cooling rate at which martensitic transformation is caused and in which the intermediate product is cooled to a temperature equal to or less than a temperature at which structure transformation due to the cooling is completed, heating the intermediate product to an austenitizing range by high-density energy and thereafter cooled at a rate equal to or more than the cooling rate at which martensitic transformation is caused to form a carburized quenched portion, cutting the extra portion of the intermediate product, and welding the first steel part and the second steel part to each other.

Abstract: A manufacturing method for a composite steel part including preparing an intermediate product in which an extra portion, which has a thickness equal to or more than that of a carburized layer to be formed in a subsequent carburizing step, has been added to a welding expected portion, carburizing the intermediate product by heating to an austenitizing temperature or more in a carburizing atmosphere, then cooling the intermediate product at a cooling rate less than a rate at which martensitic transformation occurs and without completing structural transformation due to the cooling, quenching a portion of the intermediate product after heating to an austenitizing range by high-density energy and thereafter cooling to cause martensitic transformation to form a carburized quenched portion, removing an extra portion of the intermediate product; and then welding a second steel part to the welding expected portion.

Abstract: A manufacturing method for a composite steel part including manufacturing a first steel part by preparing an intermediate product in which an extra portion is added, and heating the intermediate product to an austenitizing temperature in a carburizing atmosphere to form a carburized layer, cooling the intermediate product at a rate less than a cooling rate at which martensitic transformation is caused and in which the intermediate product is cooled to a temperature equal to or less than a temperature at which structure transformation due to the cooling is completed, heating the intermediate product to an austenitizing range by high-density energy and thereafter cooled at a rate equal to or more than the cooling rate at which martensitic transformation is caused to form a carburized quenched portion, cutting the extra portion of the intermediate product, and welding the first steel part and the second steel part to each other.

Abstract: A method of manufacturing a gear, and the resulting gear, the method resulting such that the surface layer portions of the tooth portions and a tooth root portion are made to be a carburized layer, the remaining portion of the tooth portions and a portion of a disk portion lying below the carburized layer be a quench-hardened layer, and a region of the disk portion lying deeper than the quench-hardened layer be an unquenched layer. The gear is manufactured using raw material steel having the following chemical composition: C: 0.1% to 0.40% (% by mass), Si: 0.35% to 3.0%, Mn: 0.1% to 3.0%, Cr: less than 0.2%, Mo: 0.1% or less, P: 0.03% or less, S: 0.15% or less, Al: 0.05% or less, N: 0.03% or less, and Fe and unavoidable impurities.

Abstract: A steel gear 1 includes a generally cylindrical outer peripheral ring portion 2, on an outer peripheral surface 20a of which a toothed shape 10 is formed, and a flange portion 3 provided to extend radially inward from an inner peripheral surface 20b of the outer peripheral ring portion 2. The outer peripheral ring portion 2 includes a first projecting portion 21 that projects toward one side in the axial direction with respect to a coupling position at which the first projecting portion 21 is coupled to the flange portion 3, and a second projecting portion 22 that projects toward the other side in the axial direction with respect to a coupling position at which the second projecting portion 22 is coupled to the flange portion 3. The axial length of the first projecting portion 21 is longer than the axial length of the second projecting portion 22.

Abstract: A steel gear includes a substantially cylindrical outer peripheral ring portion having a toothed shape formed on its outer peripheral surface; and a flange portion extended radially inward from an inner peripheral surface of the outer peripheral ring portion. The steel gear has a thermal history layer formed in the outer peripheral ring portion, and the depth of the thermal history layer in the direction inward from the tooth bottom of the toothed shape of the outer peripheral surface is greater in the first protruding portion and the second protruding portion than in the coupling portion with the flange portion, and is substantially the same between the first protruding portion and the second protruding portion. As a result, even if the “carburization/slow cooling/high-frequency quenching treatment” is used as a manufacturing method of the steel gear, the steel gear has high dimensional accuracy.

Abstract: A drive plate includes a disk-shaped plate portion; and a tooth-shaped portion formed at an outer peripheral end of the plate portion. The plate portion and the tooth-shaped portion are integrally shaped from a single steel plate material. The plate portion and the tooth-shaped portion include a carburized layer provided over an entire surface layer of the plate portion and the tooth-shaped portion, the carburized layer having a carbon concentration higher than that of a center portion of the plate portion and the tooth-shaped portion in a thickness direction. The carburized layer of the plate portion is higher in hardness than the center portion of the plate portion in the thickness direction. The carburized layer of the tooth-shaped portion has been subjected to a quenching process, and is further higher in hardness than the carburized layer of the plate portion.

Abstract: A manufacturing method for a composite steel part including manufacturing a first steel part by preparing an intermediate product in which an extra portion is added, and heating the intermediate product to an austenitizing temperature in a carburizing atmosphere to form a carburized layer, cooling the intermediate product at a rate less than a cooling rate at which martensitic transformation is caused and in which the intermediate product is cooled to a temperature equal to or less than a temperature at which structure transformation due to the cooling is completed, heating the intermediate product to an austenitizing range by high-density energy and thereafter cooled at a rate equal to or more than the cooling rate at which martensitic transformation is caused to form a carburized quenched portion, cutting the extra portion of the intermediate product, and welding the first steel part and the second steel part to each other.

Abstract: A manufacturing method for a composite steel part including preparing an intermediate product in which an extra portion, which has a thickness equal to or more than that of a carburized layer to be formed in a subsequent carburizing step, has been added to a welding expected portion, carburizing the intermediate product by heating to an austenitizing temperature or more in a carburizing atmosphere, then cooling the intermediate product at a cooling rate less than a rate at which martensitic transformation occurs and without completing structural transformation due to the cooling, quenching a portion of the intermediate product after heating to an austenitizing range by high-density energy and thereafter cooling to cause martensitic transformation to form a carburized quenched portion, removing an extra portion of the intermediate product; and then welding a second steel part to the welding expected portion.

Abstract: A carburized steel member is manufactured by specific carburizing, cooling, and quenching steps. The steel member contains: C: 0.1% to 0.4%, Si: 0.35% to 3.0%, Mn: 0.1% to 3.0%, P: 0.03% or less, S: 0.15% or less, Al: 0.05% or less, and N: 0.03% or less, and a content of Cr is less than 0.2%, a content of Mo is 0.1% or less, and remainder is constituted of Fe and unavoidable impurities. A surface layer thereof includes: a first layer having a carbon concentration of 0.60 mass % to 0.85 mass % and including a martensitic structure in which no grain boundary oxide layer caused by Si exists; a second layer having a carbon concentration of 0.1 mass % to 0.4 mass % and including a martensitic structure; and a third layer having a carbon concentration of 0.1 mass % to 0.4 mass % and including no martensitic structure.

Abstract: A method of manufacturing a gear, and the resulting gear, the method resulting such that the surface layer portions of the tooth portions and a tooth root portion are made to be a carburized layer, the remaining portion of the tooth portions and a portion of a disk portion lying below the carburized layer be a quench-hardened layer, and a region of the disk portion lying deeper than the quench-hardened layer be an unquenched layer. The gear is manufactured using raw material steel having the following chemical composition: C: 0.1% to 0.40% (% by mass), Si: 0.35% to 3.0%, Mn: 0.1% to 3.0%, Cr: less than 0.2%, Mo: 0.1% or less, P: 0.03% or less, S: 0.15% or less, Al: 0.05% or less, N: 0.03% or less, and Fe and unavoidable impurities.

Abstract: The present invention provides a A metal conduit for molten glass and a vacuum degassing apparatus are disclosed, which are capable of coping with extension and contraction, and vibration. By disposing at least one convex portion 20 so to have a height of 4 mm or above in a radial direction and continuously extend in a peripheral direction, it is possible to absorb thermal expansion and contraction without changing the entire length of the metal conduit 10 and to suppress from the metal conduit 10 from vibrated even when molten glass 121 is conveyed by the metal conduit. By employing the metal conduit 10 stated earlier in an upstream conveying pipe 130A, an uprising pipe 122U, a vacuum degassing vessel 120, a downfalling pipe 122L, a downstream conveying pipe 130B or the like in a vacuum degassing apparatus 30, it is possible to cope with thermal expansion and contraction, and vibration caused when conveying molten glass 121.

Abstract: The present invention provides a metal conduit for molten glass and a vacuum degassing apparatus, which are capable of coping with extension and contraction, and vibration. By disposing at least one concave portion 20 so to have a height of 4 mm or above in a radial direction and continuously extend in a peripheral direction, it is possible to absorb thermal expansion and contraction without changing the entire length of the metal conduit 10 and to suppress from the metal conduit 10 from vibrated even when molten glass 121 is conveyed by the metal conduit. By employing the metal conduit 10 stated earlier in an upstream conveying pipe 130A, an uprising pipe 122U, a vacuum degassing vessel 120, a downfalling pipe 122L, a downstream conveying pipe 130B or the like in a vacuum degassing apparatus 30, it is possible to cope with thermal expansion and contraction, and vibration caused when conveying molten glass 121.

Abstract: When molten glass which is under an atmosphere of pressure P, is fed into a vacuum chamber capable of rendering a pressure to the molten glass to be in a range of 38 [mmHg]-(P-50) [mmHg] to perform degassing to the molten glass, a staying time of the molten glass in the vacuum chamber is in a range of 0.12-4.8 hours, whereby there is obtainable an effective degassing function to the molten glass.