Steel material to be starting material of carbonitrided bearing component

Patent metadata

Field	Value
Publication number	US-11965231-B2
Application number	US-201917417735-A
Country	US
Kind code	B2
Filing date	Dec 27, 2019
Priority date	Dec 27, 2018
Publication date	Apr 23, 2024
Grant date	Apr 23, 2024

Abstract

The steel material includes a chemical composition containing, in mass %, C: 0.15 to 0.45%, Si: 0.50% or less, Mn: 0.20 to 0.60%, P: 0.015% or less, S: 0.005% or less, Cr: 0.80 to 1.50%, Mo: 0.17 to 0.30%, V: 0.24 to 0.40%, Al: 0.005 to 0.100%, N: 0.0300% or less, O: 0.0015% or less, and the balance being Fe and impurities, and satisfying Formula (1) to Formula (4) described in Embodiment, wherein, in its microstructure, a total area fraction of ferrite and pearlite is 10.0% or more, and a proportion of a content of V (mass %) in electrolytic extraction residue to the content of V (mass %) in the chemical composition is 10.0% or less.

First claim

The invention claimed is:

1. A steel material comprising a chemical composition consisting of, in mass %:
C: 0.15 to 0.45%,
Si: 0.50% or less,
Mn: 0.20 to 0.60%,
P: 0.015% or less,
S: 0.005% or less,
Cr: 0.80 to 1.50%,
Mo: 0.17 to 0.30%,
V: 0.24 to 0.40%,
Al: 0.005 to 0.100%,
N: 0.0300% or less,
O: 0.0015% or less,
Cu: 0 to 0.20%,
Ni: 0 to 0.20%,
B: 0 to 0.0050%,
Nb: 0 to 0.100%,
Ti: 0 to 0.100%,
Ca: 0 to 0.0010%, and
the balance being Fe and impurities, and
satisfying Formula (1) to Formula (4),
wherein, in its microstructure, a total area fraction of ferrite and pearlite is 10.0% or more, and the balance is bainite, and
a proportion of a content of V (mass %) in electrolytic extraction residue to the content of V (mass %) in the chemical composition is 10.0% or less:
1.50<0.4Cr+0.4Mo+4.5V<2.45  (1)

2.20<2.7C+0.4Si+Mn+0.45Ni+0.8Cr+Mo+V<2.80  (2)

Mo/V≥0.58  (3)

(Mo+V+Cr)/(Mn+20P)≥2.40  (4)

where each symbol of an element in Formula (1) to Formula (4) is to be substituted by a content of a corresponding element (mass %).

2. The steel material according to claim 1 , wherein at least one of the elements selected from the group consisting of Cu, Ni, B, Nb and Ti is present in the following amount:
Cu: 0.01 to 0.20%,
Ni: 0.01 to 0.20%,
B: 0.0001 to 0.0050%,
Nb: 0.005 to 0.100%, and
Ti: 0.005 to 0.100%.

3. The steel material according to claim 1 , wherein the Ca content is 0.0001 to 0.0010%.

4. The steel material according to claim 2 , where the CA content is 0.0001 to 0.0010%.

Assignees

• Nippon Steel Corp
• Jtekt Corp

Inventors

• Neishi Yutaka
• Yamashita Tomohiro
• Hirakami Daisuke
• Suzuki Takahisa
• Koyama Tatsuya
• Sada Takashi
• Kanetani Kohei

Classifications

• C21D8/06

  during manufacturing of rods or wires · CPC title

• C22C38/46 Primary

  with vanadium · 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

• C22C38/02 Primary

  containing silicon · CPC title