Alloy steel for low temperature vacuum carburizing

Abstract

The present invention relates to an alloy steel for low temperature vacuum carburizing, and more particularly, to an alloy steel for low temperature vacuum carburizing, wherein, where the thermal processing of carburizing and quenching is performed at 810° C. or so of an available minimum carburizing temperature of a conventional vacuum carburizing furnace, it is able to securing an adequate ferrite phase (α) to improve the thermal distortion according to the thermal processing of an annulus gear, and to satisfying shape restrictions such as a roundness or a cylindricity of the annulus gear to be manufactured. An alloy steel for a low temperature vacuum carburizing according to the present invention, the alloy steel is composed of a chief element of Fe, wherein the alloy steel is formed so that dissolved oxygen (DO) is 10 ppm or less in an alloy system which comprises 0.17˜0.24 weight percent of C, 0.8˜1.2 weight percent of Cr, 0.4˜0.8 weight percent of Mn, 0.80˜1.20 weight percent of Si, 0.020 weight percent or less of P, 0.020 weight percent or less of S, 0.015˜0.045 weight percent of V, and the remaining weight percent of Fe.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]The present application claims under 35 U.S.C. §119(a) to the benefit of Korean Patent Application Number 10˜2009˜0117993, filed on 1, Dec., 2009, the entire contents of which is incorporated herein for all purposes by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates, generally, to an alloy steel for low temperature vacuum carburizing, and more particularly, to an alloy steel for low temperature vacuum carburizing, wherein, when the thermal processing of carburizing and quenching is performed at 810° C. or so of an available minimum carburizing temperature of a conventional vacuum carburizing furnace, it is able to securing an adequate ferrite phase (α) to suitably improve the thermal distortion according to the thermal processing of an annulus gear, and to suitably satisfy shape restrictions of the annulus gear to be manufactured, such as, but not limited to, roundness or cylindricity...

AI Technical Summary

Benefits of technology

[0016]Preferably, the alloy steel for a low temperature vacuum carburizing of the present invention, in certain preferred embodiments, where the thermal processing of carburizing and quenching is performed at 810° C. or so of an available minimum carburizing temperature of a conventional vacuum carburizing furnace, reaches an adequate ferrite phase (α) to suitably improve the thermal distortion according to the thermal processing of the annulus gear, and to suitably satisfies shape restrictions such as a roundness or a cylindricity of the annulus gear to be manufactured.

Problems solved by technology

When the thermal processing of carburizing and quenching is performed, distortion of the components may occur.

In certain cases where the distortion is excessive, it may cause problems with the assembly of the components, or unusual noise may occur.

Since the annulus gear has a large diameter and a thin thickness, it is very sensitive to thermal distortion.

Further, while teeth surface processing of a general external gear is easily performed after the thermal processing such as grinding or the like, the annulus gear is one of the components whose processing is difficult after the thermal processing.

However, the above-described method involves long and complex processing.

Further, since the method is individually performed by components, the operation efficiency may suitably decrease.

Further, when the jig is cooled, a shape of gear teeth may suitably deform unevenly by a localized uneven cooling, and accordingly, unusual noise may occur.

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