Steel shaft component

Patent metadata

Field	Value
Publication number	US-2022177991-A1
Application number	US-202017593593-A
Country	US
Kind code	A1
Filing date	Apr 9, 2020
Priority date	Apr 10, 2019
Publication date	Jun 9, 2022
Grant date	—

Abstract

The steel shaft component consists of C: 0.40 to 0.60%, Si: 0.05 to 1.00%, Mn: 1.00 to 2.00%, P: 0.030% or less, S: 0.005 to 0.100%, Cr: 0.10 to 0.50%, V: 0.10 to 0.30%, Al: 0.005 to 0.050%, N: 0.0050 to 0.0200%, Ti: 0 to 0.050%, and the balance: Fe and impurities. A Vickers hardness Hs of the surface of the shaft part is 620 HV or more. A Vickers hardness Hb at an R/2 position satisfies Formula (1). A depth of the hardened layer Hr (mm) having a Vickers hardness of 620 HV or more satisfies Formula (2). The microstructure at the R/2 position is composed of ferrite and pearlite. Within the hardened layer, the number of density of V-containing precipitates having an equivalent circular diameter of more than 100 nm is 10 particles/276 μm2 or less.Hs/2.3≤Hb≤350  (1)0.05≤Hr/R≤0.40  (2)

First claim

1 . A steel shaft component, comprising:
one or a plurality of shaft parts, each of the shaft part having a circular shape in a cross section perpendicular to an axial direction, and having a hardened layer having a Vickers hardness of 620 HV or more in an outer layer; wherein: a chemical composition of the steel shaft component consists of, by mass %, C: 0.40 to 0.60%, Si: 0.05 to 1.00%, Mn: 1.00 to 2.00%, P: 0.030% or less, S: 0.005 to 0.100%, Cr: 0.10 to 0.50%, V: 0.10 to 0.30%, Al: 0.005 to 0.050%, N: 0.0050 to 0.0200%, Ti: 0 to 0.050%, and the balance: Fe and impurities; a Vickers hardness Hs of a surface of the shaft part is 620 HV or more; in the cross section perpendicular to the axial direction of the shaft part, a Vickers hardness Hb at an R/2 position that corresponds to a center position of a radius R of the shaft part satisfies Formula (1); a microstructure at the R/2 position is composed of ferrite and pearlite; a depth Hr (mm) of the hardened layer having a Vickers hardness of 620 HV or more satisfies Formula (2); and in the hardened layer of the cross section perpendicular to the axial direction of the shaft part, a number of density of V-containing precipitates which contain V and which have an equivalent circular diameter of more than 100 nm is 10 particles/276 μm 2 or less:
Hs/ 2.3≤ Hb≤ 350  (1)

0.05≤ Hr/R≤ 0.40  (2)

where, R in Formula (2) represents a radius (mm) of the shaft part.

2 . The steel shaft component according to claim 1 , wherein:
the chemical composition contains, by mass %, Ti: 0.005 to 0.050%.

3 . The steel shaft component according to claim 1 , wherein:
the steel shaft component is a crankshaft or a camshaft.

4 . The steel shaft component according to claim 2 , wherein:
the steel shaft component is a crankshaft or a camshaft.

Assignees

• Nippon Steel Corp

Inventors

• Nishihara Kison
• Tahira Hiroaki
• Sueyasu Yoko

Classifications

• C22C38/04

  containing manganese · CPC title

• C21D9/30 Primary

  for crankshafts; for camshafts · CPC title

• C22C38/28

  with titanium or zirconium · CPC title

• C22C38/001

  containing N · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title