Steel wire for springs having excellent fatigue properties, and spring

Patent metadata

Field	Value
Publication number	US-2016348221-A1
Application number	US-201515115185-A
Country	US
Kind code	A1
Filing date	Jan 29, 2015
Priority date	Jan 29, 2014
Publication date	Dec 1, 2016
Grant date	—

Abstract

A steel wire rod for a spring includes: C: 0.2 to 1.2%, Si: 1.0 to 3%, Mn: 0.1 to 2%, Cr: 3% or less (not inclusive of 0%), Al: 0.0002 to 0.005%, Ca: 0.0002 to 0.002%, Ti: 0.0003 to 0.010%, and balance: iron and unavoidable impurities. An average composition of oxide-based inclusions having a minor axis of 1 μm or more which are present in a cross section satisfies CaO: 35% or less, Al 2 O 3 : 40% or less, SiO 2 : 30 to 95%, MgO: 8% or less, MnO: 5% or less, TiO 2 : 3 to 10%, and CaO+Al 2 O 3 +SiO 2 +MgO+MnO+TiO 2 ≧80%. The number of oxide-based inclusions having a minor axis of 2 μm or more which are present in the cross section is more than 0.002 inclusions/mm 2 .

First claim

1 . A steel wire rod for a spring excellent in fatigue properties, comprising:
C: 0.2 to 1.2%, where % means mass %, hereinafter the same, unless otherwise indicated, Si: 1.0 to 3%, Mn: 0.1 to 2%, Cr: 3% or less but not inclusive of 0%, Al: 0.0002 to 0.005%, Ca: 0.0002 to 0.002%, Ti: 0.0003 to 0.010%, and balance: iron and unavoidable impurities, wherein an average composition of oxide-based inclusions having a minor axis of 1 μm or more which are present in a cross section parallel to a longitudinal direction of a steel satisfies, by mass %, CaO: 35% or less and inclusive of 0%, Al 2 O 3 : 40% or less and inclusive of 0%, SiO 2 : 30 to 95%, MgO: 8% or less and inclusive of 0%, MnO: 5% or less and inclusive of 0%, TiO 2 : 3 to 10%, and CaO+Al 2 O 3 +SiO 2 +MgO+MnO+TiO 2 ≧80%, and the number of oxide-based inclusions having a minor axis of 2 μm or more which are present in the cross section is more than 0.002 inclusions/mm 2 .

2 . The steel wire rod for a spring according to claim 1 , wherein the average composition of the oxide-based inclusions further satisfies, by mass %, ZrO 2 : less than 1% but not inclusive of 0% and Na 2 O: less than 5% and inclusive of 0%.

3 . The steel wire rod for a spring according to claim 1 , further comprising at least one of Ni: 0.5% or less but not inclusive of 0%, Cu: 0.5% or less but not inclusive of 0% and V: 0.5% or less but not inclusive of 0%.

4 . A spring obtained using the steel wire rod for a spring according to claim 1 .

5 . The steel wire rod for a spring according to claim 2 , further comprising at least one of Ni: 0.5% or less but not inclusive of 0%, Cu: 0.5% or less but not inclusive of 0% and V: 0.5% or less but not inclusive of 0%.

6 . A spring obtained using the steel wire rod for a spring according to claim 2 .

7 . A spring obtained using the steel wire rod for a spring according to claim 3 .

8 . A spring obtained using the steel wire rod for a spring according to claim 5 .

Assignees

• Kobe Steel Ltd

Inventors

• Sugimura Tomoko
• Shimamoto Masaki
• Shindo Yosuke
• Kaizuka Masaki
• Owaki Akihiro
• Kimura Sei

Classifications

• C22C38/38

  with more than 1.5% by weight of manganese · CPC title

• C22C38/28

  with titanium or zirconium · CPC title

• C22C38/18 Primary

  containing chromium · CPC title

• C22C38/002

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

• C21D2211/004

  Dispersions; Precipitations · CPC title