In a heater unit for a carburizing furnace that carburizes a workpiece, a heater that heats a furnace atmosphere; and a heater supporting member that reflects radiant heat of the heater are provided, in which a heat generation part of the heater is attached to the heater supporting member, and a heat generation body composing the heat generation part is formed in a bellows shape.

In a heater unit for a carburizing furnace that carburizes a workpiece, a heater that heats a furnace atmosphere; and a heater supporting member that reflects radiant heat of the heater are provided, in which a heat generation part of the heater is attached to the heater supporting member, and a heat generation body composing the heat generation part is formed in a bellows shape.

A method for heat treating a steel component, which comprises the steps of: (a) carburizing the steel component with a carbon potential above 1.0, (b) carburizing the steel component with a carbon potential above 0.6, (c) quenching the steep component, and (d) subjecting the steel component to a bainitic treatment.

A method for heat treating a steel component, which comprises the steps of: (a) carburizing the steel component with a carbon potential above 1.0, (b) carburizing the steel component with a carbon potential above 0.6, (c) quenching the steep component, and (d) subjecting the steel component to a bainitic treatment.

A method for manufacturing a golf club head having an embedded heterogeneous material includes preparing a shell mold having a cavity and a functional member embedded into the shell mold via an embedded portion, filling the cavity with a metal liquid to completely dip the non-embedded portion of the functional member in the metal liquid; breaking the shell mold to obtain a cast product, separating the golf club head cast member from the cast product to obtain a semi-finished golf club head having a casting material and a heterogeneous material, and pressing the casting material of the semi-finished golf club head to securely engage the casting material with the heterogeneous material. The functional member includes a non-embedded portion connected to the embedded portion and located in the cavity. The cast product includes a golf club head cast member.

A method for manufacturing a golf club head having an embedded heterogeneous material includes preparing a shell mold having a cavity and a functional member embedded into the shell mold via an embedded portion, filling the cavity with a metal liquid to completely dip the non-embedded portion of the functional member in the metal liquid; breaking the shell mold to obtain a cast product, separating the golf club head cast member from the cast product to obtain a semi-finished golf club head having a casting material and a heterogeneous material, and pressing the casting material of the semi-finished golf club head to securely engage the casting material with the heterogeneous material. The functional member includes a non-embedded portion connected to the embedded portion and located in the cavity. The cast product includes a golf club head cast member.

A method of manufacturing a roller cone for a drill bit includes: selectively carburizing a land of the roller cone between a plurality of spots on the land for protection against erosion; after carburization, forming sockets in the roller cone at the spots; and mounting cermet inserts in the sockets.

A process for manufacturing a bellows, made of austenitic high-grade steel with high compressive strength and fatigue strength, forms a single-layer or multilayer sleeve into a bellows with hydraulic forming. The pressure resistance and fatigue strength are improved by the bellows being cleaned after the forming and by the bellows being exposed to a surrounding area containing carbon and/or nitrogen atoms at temperatures between 100° C. and 400° C., preferably 200° C. to 320° C. With this a hardening of the bellows takes place by means of the diffusing in of carbon and/or nitrogen atoms. A bellows made of austenitic high-grade steel with one or more layers created in this manner has the edge layer hardened by the incorporation of carbon and/or nitrogen atoms up to a hardening depth of at least 5% of the wall thickness.

A process for manufacturing a bellows, made of austenitic high-grade steel with high compressive strength and fatigue strength, forms a single-layer or multilayer sleeve into a bellows with hydraulic forming. The pressure resistance and fatigue strength are improved by the bellows being cleaned after the forming and by the bellows being exposed to a surrounding area containing carbon and/or nitrogen atoms at temperatures between 100° C. and 400° C., preferably 200° C. to 320° C. With this a hardening of the bellows takes place by means of the diffusing in of carbon and/or nitrogen atoms. A bellows made of austenitic high-grade steel with one or more layers created in this manner has the edge layer hardened by the incorporation of carbon and/or nitrogen atoms up to a hardening depth of at least 5% of the wall thickness.

A steel for a carburizing and a carburized steel component having a steel portion and a carburized layer with a thickness of more than 0.4 mm to less than 2 mm which is formed on an outside of the steel portion. A chemical composition of the steel for the carburizing and the steel portion of the carburized steel component satisfies simultaneously equations of a hardness parameter, a hardenability parameter, and a TiC precipitation parameter.