Case-hardening steel and case-hardened steel member

a technology of case-hardening steel and hardening steel, which is applied in the direction of solid-state diffusion coating, coating, metallic material coating process, etc., can solve the problems of not considering the prevention of crack initiation, no description of cold forging, and no description of a technique for improving temper softening resistance, etc., to achieve excellent cold forging, excellent temper softening resistance, and high hardness of a carburized layer. excellent
US20160060744A1Inactive Publication Date: 2016-03-03NIPPON STEEL & SUMITOMO METAL CORP
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Patent Information

Authority / Receiving Office
US · United States
Current Assignee / Owner
NIPPON STEEL & SUMITOMO METAL CORP
Publication Date
2016-03-03
Estimated Expiration
Not applicable · inactive patent

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Abstract

There is provided a case-hardening steel in which in inclusion evaluation using an extreme value statistical method, when an estimated area S is 30,000 mm2, an estimated value of the maximum size (√area)S of sulfide-based inclusions present in the estimated area S is 49 μm or less and an estimated value of the maximum size (√area)Ox of oxide-based inclusions present in the estimated area S is 80 μm or less, and the number of sulfide-based inclusions having a length of more than 20 μm and a thickness of more than 2 μm per 1 mm2 is limited to 200 or less,
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Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a case-hardening steel and a case-hardened steel member, and particularly to a case-hardening steel, which has excellent cold forgeability and capable of obtaining excellent temper softening resistance after a carburizing treatment or a carbonitriding quenching and tempering treatment, and is suitable for components for automobiles, construction machines, and industrial machines, and a case-hardened steel member.

[0002] Priority is claimed on Japanese Patent Application No. 2013-087857, filed Apr. 18, 2013, the content of which is incorporated herein by reference.RELATED ART

[0003] Transmission gears used in automobiles, construction machines, etc. and reduction gears used in industrial machines, etc. are mainly configured by gears. These components can be obtained by using a medium carbon alloy steel such as JIS SCr 420, JIS SCM 420, etc. as a material, forming the material into the shape of a component by hot forgi...

Claims

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