# US 10,370,747 B2 · Nitrided component

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- Number: US 10,370,747 B2
- Document ID: US10370747B2
- Status: Granted
- Kind: B2
- Application number: 15/623,434
- Filed: 2017-06-15
- Published: 2017-10-05
- Granted: 2019-08-06
- Earliest claimed: 2011-02-01
- Assignees: Nippon Steel Corporation; Honda Motor Co., Ltd.
- Applicants: Nippon Steel & Sumitomo Metal Corporation; Honda Motor Co., Ltd.
- Inventors: Hideki Imataka; Masato Yuya; Yuya Gyotoku; Atsushi Kobayashi; Susumu Maeda
- Web page: https://patentgrep.com/patent/US10370747B2

## CPC

- C22C 38/50: with titanium or zirconium
- C21D 1/06: Surface hardening
- C21D 9/32: for gear wheels, worm wheels, or the like
- C22C 38/001: {containing N}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/20: with copper
- C22C 38/22: with molybdenum or tungsten
- C22C 38/24: with vanadium
- C22C 38/28: with titanium or zirconium
- C22C 38/44: with molybdenum or tungsten
- C22C 38/46: with vanadium
- C23C 8/26: of ferrous surfaces
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)

## Abstract

A nitrided component has a chemical composition consisting of, by mass percent, C: 0.07-0.14%, Si: 0.10-0.30%, Mn: 0.4-1.0%, S: 0.005-0.030%, Cr: 1.0-1.5%, Mo: ≤0.05% (including 0%), Al: 0.010% or more to less than 0.10%, V: 0.10-0.25%, optionally at least one element selected from Cu: ≤0.30% and Ni: ≤0.25%, [0.61Mn+1.11Cr+0.35Mo+0.47V≤2.30], and the balance of Fe and impurities. P, N, Ti and O among the impurities are P: ≤0.030%, N: ≤0.008%, Ti: ≤0.005%, and O: ≤0.0030%. The nitrided composition is suitable for use as an automobile ring gear. The nitrided component has a surface hardness of 650-900 HV, core hardness being ≥150 HV, effective case depth of ≥0.15 mm, has excellent bending fatigue strength and surface fatigue strength although the content of Mo is as low as ≤0.05% and has a small amount of expansion caused by nitriding.

## Claims

### Claim 1

A nitrided component having a chemical composition consisting of, by mass percent, C: 0.07 to 0.14%, Si: 0.10 to 0.30%, Mn: 0.4 to 1.0%, S: 0.005 to 0.030%, Cr: 1.0 to 1.5%, Mo: 0.05% or less (including 0%), Al: 0.010% or more to less than 0.10%, and V: 0.10 to 0.25%, Fn1 expressed by Formula (1) is 2.30 or less, and the balance of Fe and impurities, wherein P, N, Ti and O among the impurities are P: 0.030% or less, N: 0.008% or less, Ti: 0.005% or less, and O: 0.0030% or less, in which the surface hardness is 650 to 900 in Vickers hardness, the core hardness is 150 or higher in Vickers hardness, and the effective case depth is 0.15 mm or larger:
Fn1=0.61Mn+1.11Cr+0.35Mo+0.47V (1)
where, the symbol of each element in Formula (1) represents the content thereof in mass percent.

### Claim 2

A nitrided component having a chemical composition consisting of, by mass percent, C: 0.07 to 0.14%, Si: 0.10 to 0.30%, Mn: 0.4 to 1.0%, S: 0.005 to 0.030%, Cr: 1.0 to 1.5%, Mo: 0.05% or less (including 0%), Al: 0.010% or more to less than 0.10%, and V: 0.10 to 0.25%, Fn1 expressed by Formula (1) is 2.30 or less, at least one element selected from, by mass percent, Cu: 0.30% or less and Ni: 0.25% or less, and the balance of Fe and impurities, wherein P, N, Ti and O among the impurities are P: 0.030% or less, N: 0.008% or less, Ti: 0.005% or less, and O: 0.0030% or less, in which the surface hardness is 650 to 900 in Vickers hardness, the core hardness is 150 or higher in Vickers hardness, and the effective case depth is 0.15 mm or larger:
Fn1=0.61Mn+1.11Cr+0.35Mo+0.47V (1)
where, the symbol of each element in Formula (1) represents the content thereof in mass percent.