An oil-immersion quenching cooling precursor and an oil-immersion quenching cooling method includes an axle-type workpiece or a workpiece that has sections in an axle form. Several separation rings are arranged on the workpiece in the axial direction to separate the axle-type workpiece or the workpiece that has sections in an axle form into a plurality of sections before oil-immersion quenching cooling. In the method, there is a cutting procedure before a quenching cooling procedure. Several separation rings distributed in the axial direction are reserved outside a dimension required for the workpiece. sections before oil-immersion quenching cooling. In the method, there is a cutting procedure before a quenching cooling procedure. Several separation rings distributed in the axial direction are reserved outside a dimension required for the workpiece.

An oil-immersion quenching cooling precursor and an oil-immersion quenching cooling method includes an axle-type workpiece or a workpiece that has sections in an axle form. Several separation rings are arranged on the workpiece in the axial direction to separate the axle-type workpiece or the workpiece that has sections in an axle form into a plurality of sections before oil-immersion quenching cooling. In the method, there is a cutting procedure before a quenching cooling procedure. Several separation rings distributed in the axial direction are reserved outside a dimension required for the workpiece. sections before oil-immersion quenching cooling. In the method, there is a cutting procedure before a quenching cooling procedure. Several separation rings distributed in the axial direction are reserved outside a dimension required for the workpiece.

Disclosed is a quenching method for a quenching object including a race provided with an object through hole. The quenching method includes a step of preparing a quenching tool which is a rod body, a step of suspending a plurality of the quenching objects on the rod body by inserting the quenching tool into the object through hole, and a step of immersing the quenching tool and the quenching objects in a cooling oil. In the step of suspending, each of the quenching objects is disposed on the rod body such that a contact state between the quenching tool and the object through hole is line contact.

Disclosed is a quenching method for a quenching object including a race provided with an object through hole. The quenching method includes a step of preparing a quenching tool which is a rod body, a step of suspending a plurality of the quenching objects on the rod body by inserting the quenching tool into the object through hole, and a step of immersing the quenching tool and the quenching objects in a cooling oil. In the step of suspending, each of the quenching objects is disposed on the rod body such that a contact state between the quenching tool and the object through hole is line contact.

An intensive quenching (IQ) apparatus and method of quenching heated parts is provided. The IQ apparatus includes a chute for placing parts into a tank including liquid quenchant. The parts fall through the quenchant in the chute and are received by a conveyor belt. The parts are then transported on the conveyor through an inner channel of a conduit. An agitation rate of the quenchant in the inner channel is increased by an agitator.

An intensive quenching (IQ) apparatus and method of quenching heated parts is provided. The IQ apparatus includes a chute for placing parts into a tank including liquid quenchant. The parts fall through the quenchant in the chute and are received by a conveyor belt. The parts are then transported on the conveyor through an inner channel of a conduit. An agitation rate of the quenchant in the inner channel is increased by an agitator.

A steel sheet having a steel microstructure including, by area %, martensite in a range of 20% or more and 100% or less, ferrite in a range of 0% or more and 80% or less, and the balance being 5% or less. A residual stress generated at the transverse center of the steel sheet when the steel sheet is subjected to a V-bending process is 800 MPa or less. A residual stress generated at the transverse end of the steel sheet when the steel sheet is subjected to a V-bending process is 90% or more and 110% or less of the residual stress generated at the transverse center of the steel sheet. The maximum amount of warpage of the steel sheet sheared to a length of 1 m in the longitudinal direction is 15 mm or less.

A method of manufacturing a cam piece for a continuously variable valve duration and a cam piece manufactured therefrom, and more particularly, to material and heat treatment conditions of a cam piece, may include manufacturing a cam piece by casting; heating the cam piece; maintaining a heating temperature; and salt-bathing the cam piece, in which the cam piece includes 3.2 to 4.2 wt % of carbon (C), 2.2 to 3.4 wt % of silicon (Si), and the balance iron (Fe), and may have a carbon equivalent value of 4.4 to 4.6.

A method for heat treating cast aluminum alloy components that includes obtaining a casting formed from an aluminum alloy having a silicon constituent and at least one metal alloying constituent, and heating the casting to a first casting temperature that is below but within 10° C. of a predetermined silicon solution temperature at which the silicon constituent rapidly enters into solid solution. The method also includes increasing the rate of heat input into the casting to raise the temperature of the casting to a second casting temperature that is above but within 10° C. of a predetermined alloying metal solution temperature at which the at least one metal alloying constituent rapidly enters into solid solution, maintaining the casting at the second casting temperature for a period of time that is less than about 20 minutes, and then quenching the casting to a temperature less than or about 250° C.

A method for heat treating cast aluminum alloy components that includes obtaining a casting formed from an aluminum alloy having a silicon constituent and at least one metal alloying constituent, and heating the casting to a first casting temperature that is below but within 10° C. of a predetermined silicon solution temperature at which the silicon constituent rapidly enters into solid solution. The method also includes increasing the rate of heat input into the casting to raise the temperature of the casting to a second casting temperature that is above but within 10° C. of a predetermined alloying metal solution temperature at which the at least one metal alloying constituent rapidly enters into solid solution, maintaining the casting at the second casting temperature for a period of time that is less than about 20 minutes, and then quenching the casting to a temperature less than or about 250° C.