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1. (WO2018056333) CARBURIZED SHAFT COMPONENT

Pub. No.:    WO/2018/056333    International Application No.:    PCT/JP2017/033987
Publication Date: Fri Mar 30 01:59:59 CEST 2018 International Filing Date: Thu Sep 21 01:59:59 CEST 2017
IPC: C21D 9/28
C21D 1/06
C22C 38/00
C22C 38/38
C22C 38/60
F16C 3/02
Applicants: NIPPON STEEL & SUMITOMO METAL CORPORATION
新日鐵住金株式会社
Inventors: IWASAKI, Tatsuya
岩崎 竜也
WATARI, Koji
渡里 宏二
SUENO, Hidekazu
末野 秀和
Title: CARBURIZED SHAFT COMPONENT
Abstract:
Provided is a carburized shaft component characterized by having a prescribed composition, having a C content of 0.60-1.00 mass% in the surface layer section thereof, having one or more holes in the outer-circumferential surface thereof, and in that: the total percentage by volume of martensite and retained austenite in the composition from the outer-circumferential surface to a depth of 1mm in the axial direction of the holes and from the surface of the holes to a depth of 20μm is 97%; the maximum percentage (R1) by volume of the retained austenite in the range from the outer-circumferential surface to a depth of 1mm in the axial direction of the holes and from the surface of the holes to a depth of 200μm is 10.0-30.0%; and the reduction rate of the retained austenite is 20% or higher according to formula (A): Δγ=(R1-R2)/R1×100, which uses R1 mentioned above and R2, which is the percentage (R2) by volume of the retained austenite from the outer-circumferential surface to a depth of 1mm in the axial direction of the holes and from the surface of the holes to a depth of 20μm.