# US 12,006,994 B2 · Valve spring

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- Number: US 12,006,994 B2
- Document ID: US12006994B2
- Status: Granted
- Kind: B2
- Application number: 17/754,667
- Filed: 2020-10-15
- Published: 2024-03-07
- Granted: 2024-06-11
- Earliest claimed: 2019-10-16
- Assignees: Nippon Steel Corporation; NHK Spring Co., Ltd.; Nippon Steel Sg Wire Co., Ltd.
- Applicants: Nippon Steel Corporation; Nhk Spring Co., Ltd.; Nippon Steel Sg Wire Co., Ltd.
- Inventors: Shinya Teramoto; Yutaka Neishi; Michimasa Aono; Shuji Kozawa; Fumio Takahashi; Shigekazu Nishimoto; Mitsuhiro Kondo; Tatsuro Ochi; Shoichi Suzuki
- Web page: https://patentgrep.com/patent/US12006994B2

## CPC

- F16F 1/021: {characterised by their composition, e.g. comprising materials providing for particular spring properties (composition and manufacture of clock or watch springs G04B1/145)}
- C21C 7/0006: {Adding metallic additives}
- C21C 7/076: Use of slags or fluxes as treating agents (C21C7/06, C21C7/064, C21C7/068 take precedence)
- C21D 1/18: Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62)
- C21D 1/25: Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
- C21D 1/26: Methods of annealing
- C21D 1/30: Stress-relieving
- C21D 6/004: {containing Cr and Ni}
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- C21D 7/06: by shot-peening or the like
- C21D 8/00: Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02)
- C21D 8/06: during manufacturing of rods or wires
- C21D 9/02: for springs
- C21D 9/525: {for wire, for rods (C21D9/54 takes precedence)}
- C22C 38/001: {containing N}
- C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60}
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/22: with molybdenum or tungsten
- C22C 38/24: with vanadium
- C22C 38/26: with niobium or tantalum
- C22C 38/34: with more than 1.5% by weight of silicon
- C22C 38/42: with copper
- C22C 38/44: with molybdenum or tungsten
- C22C 38/46: with vanadium
- C22C 38/48: with niobium or tantalum
- C22C 38/50: with titanium or zirconium
- C23C 8/02: Pretreatment of the material to be coated (C23C8/04 takes precedence)
- C23C 8/26: of ferrous surfaces
- C23C 8/80: After-treatment
- C21D 2211/004: Dispersions; Precipitations
- C21D 2211/008: Martensite
- C22C 33/06: using master alloys
- C22C 2202/02: Magnetic
- F16F 2224/02: solids
- F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- C21C: PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- 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)
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- 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 valve spring includes a nitrided layer, and a core portion that is further inward than the nitrided layer. A chemical composition of the core portion consists of, in mass %, C: 0.53 to 0.59%, Si: 2.51 to 2.90%, Mn: 0.70 to 0.85%, P: 0.020% or less, S: 0.020% or less, Cr: 1.40 to 1.70%, Mo: 0.17 to 0.53%, V: 0.23 to 0.33%, Ca: 0.0001 to 0.0050%, Cu: 0.050% or less, Ni: 0.050% or less, Al: 0.0050% or less, Ti: 0.050% or less, and N: 0.0070% or less, with the balance being Fe and impurities. In the core portion, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 500 to 8000 per μm2, and in the core portion, a numerical proportion of Ca sulfides with respect to a total number of oxide-based inclusions and sulfide-based inclusions is 0.20% or less.

## Claims

### Claim 1

A valve spring, comprising:
a nitrided layer formed in an outer layer, and
a core portion that is further inward than the nitrided layer;
wherein:
a chemical composition of the core portion consists of, in mass %,
C: 0.53 to 0.59%,
Si: 2.51 to 2.90%,
Mn: 0.70 to 0.85%,
P: 0.020% or less,
S: 0.020% or less,
Cr: 1.40 to 1.70%,
Mo: 0.17 to 0.53%,
V: 0.23 to 0.33%,
Ca: 0.0001 to 0.0050%,
Cu: 0.050% or less,
Ni: 0.050% or less,
Al: 0.0050% or less,
Ti: 0.050% or less,
N: 0.0070% or less, and
Nb: 0 to 0.020%,
with the balance being Fe and impurities;
in the core portion, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 500 to 8000 pieces/μm2; and
when, among inclusions in the core portion,
inclusions in which, in mass %, an O content is 10.0% or more are defined as oxide-based inclusions,
inclusions in which, in mass %, an S content is 10.0% or more and the O content is less than 10.0% are defined as sulfide-based inclusions, and
among the sulfide-based inclusions, inclusions in which, in mass %, a Ca content is 10.0% or more, the S content is 10.0% or more, and the O content is less than 10.0% are defined as Ca sulfides,
in the core portion, a numerical proportion of the Ca sulfides with respect to a total number of the oxide-based inclusions and the sulfide-based inclusions is 0.20% or less.

### Claim 2 (depends on 1)

The valve spring according to claim 1, wherein:
in the chemical composition of the core portion:
an Nb content is 0.005 to 0.020%.