Steel material for vacuum carburization, and method of manufacturing the same

A manufacturing method and carburizing technology, which is applied in the field of carburized parts, can solve the problems of inability to obtain miniaturized surface fatigue strength and bending fatigue strength, and insufficient improvement of surface softening characteristics, and achieve excellent bending fatigue strength and surface fatigue strength. The effect of excellent strength

CN107653420AInactive Publication Date: 2018-02-02KOBE STEEL LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2018-02-02
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention provides a carburization part having sufficient surface fatigue strength and a carburization part having surface fatigue strength and flex fatigue strength; and a steel material for obtaining the carburization parts. The present invention is a steel material for vacuum carburization containing C, Si, Mn, S, P, Cr, Mo, V, Al, and N, in which an average circle-equivalent diameter of avanadium carbide is 25 nm or less. The present invention also includes a method for manufacturing the steel material. Specifically, the method includes subjecting a steel having a predetermined chemical ingredient composition to blooming by holding the steel at 1200 DEG C or above for 30-300 minutes, followed by hot rolling by setting a heating temperature before the hot rolling to 950 DEG C or above and heating retention time to 30 minutes to 5 hours.
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Description

[0001] This application is a divisional application of PCT / JP2015 / 057833 with application number: 201580014824.7, application date: 2015.3.17, and title of invention: "Steel for vacuum carburizing and its manufacturing method". technical field

[0002] The present invention relates to a steel material for vacuum carburizing, and more specifically, to a steel material for obtaining a carburized part having excellent surface fatigue properties and bending fatigue properties after vacuum carburizing, and to a manufacturing method and a steel material using the same carburized parts, and methods of making such parts. The steel material of the present invention is useful as raw materials such as gears and shafts used in automobiles, construction machinery, and various other industrial machinery. Hereinafter, the case where it is applied to automobile gears will be described as an example, but it is not limited thereto. mean. Background technique

[0003] Looking at the environme...

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Embodiment

[0095] Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited by the following examples, and within the range that can meet the above-mentioned and hereinafter-described purposes, of course, it can also be appropriately modified and implemented, and these are included in the technical scope of the present invention.

[0096] Steels having the chemical composition shown in Table 1 below were melted, held at 1250° C. for 30 minutes to 300 minutes, and then billet-rolled. The balance of the chemical composition shown in Table 1 is iron and unavoidable impurities. Thereafter, as shown in Tables 2 and 3, the pre-rolling heating temperature is 920° C. to 1100° C., and the heating retention time is 0.3 to 6 hours to perform hot rolling to obtain The hot-rolled material, that is, bar steel. Note that Steel No. 1 shown in Table 1 is a steel equivalent to the conventional steel SCr420H.

[0097] [Table ...