Title:
STEEL FOR SPRING AND METHOD FOR PRODUCING SAME, AND SPRING
Document Type and Number:
WIPO Patent Application WO/2013/146214
Kind Code:
A1
Abstract:
Provided are: a steel for a spring, which has tensile strength of 1800 MPa or more and therefore has high strength and also has high ductility; a method for producing the steel; and a spring. A steel for a spring, which has a total composition comprising, in mass%, 0.45 to 0.70% of C, 1.0 to 2.2% of Si, 0.1 to 1.0% of Mn, 0.1 to 1.0% of Cr, 0.035% or less of P, 0.035% or less of S, 0.05 to 0.35% V and a remainder made up by iron and unavoidable impurities, said steel being characterized in that, with respect to the areal ratios of inner structures on an arbitrary cross section, lower bainite makes up 65% or more and retained austenite makes up 2.0 to 15.0%, with the remainder (including 0%) made up by martensite, wherein the average C concentration in the retained austenite is 1.0 to 2.7%.
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Inventors:
SHIBAIRI KOSUKE (JP)
SUZUKI TAKESHI (JP)
ONO YOSHIKI (JP)
KUROKAWA SHIMPEI (JP)
SUZUKI TAKESHI (JP)
ONO YOSHIKI (JP)
KUROKAWA SHIMPEI (JP)
Application Number:
PCT/JP2013/056655
Publication Date:
October 03, 2013
Filing Date:
March 11, 2013
Export Citation:
Assignee:
NHK SPRING CO LTD (JP)
International Classes:
C22C38/00; C21D6/00; C21D9/02; C22C38/34; F16F1/02
Domestic Patent References:
| WO2010110041A1 | 2010-09-30 |
Foreign References:
| JP3034543B2 | 2000-04-17 | |||
| US20040025987A1 | 2004-02-12 | |||
| JPH06271930A | 1994-09-27 | |||
| JP3318435B2 | 2002-08-26 | |||
| JP2001064752A | 2001-03-13 |
Other References:
TAKESHI SUZUKI ET AL.: "Microstructure and Mechanical Properties of Austempered Medium Carbon Steels", JOURNAL OF THE IRON & STEEL INSTITUTE OF JAPAN, vol. 97, no. 1, 1 January 2011 (2011-01-01), pages 26 - 33
TAKESHI SUZUKI ET AL.: "Effects of Si and Cr on Bainite Microstructure of Medium Carbon Steels", JOURNAL OF THE IRON & STEEL INSTITUTE OF JAPAN, vol. 96, no. 6, 4 June 2010 (2010-06-04), pages 392 - 399, XP055142669, DOI: doi:10.2355/tetsutohagane.96.392
JOSE ALBERTO DA CRUZ JUNIOR ET AL.: "Bainite Formation at Low Temperatures in High C-Si Steel and its Mechanical Behavior", MATERIALS SCIENCE FORUM, vol. 706-709, 3 February 2012 (2012-02-03), pages 173 - 180
TAKESHI SUZUKI ET AL.: "Effects of Si and Cr on Bainite Microstructure of Medium Carbon Steels", JOURNAL OF THE IRON & STEEL INSTITUTE OF JAPAN, vol. 96, no. 6, 4 June 2010 (2010-06-04), pages 392 - 399, XP055142669, DOI: doi:10.2355/tetsutohagane.96.392
JOSE ALBERTO DA CRUZ JUNIOR ET AL.: "Bainite Formation at Low Temperatures in High C-Si Steel and its Mechanical Behavior", MATERIALS SCIENCE FORUM, vol. 706-709, 3 February 2012 (2012-02-03), pages 173 - 180
Attorney, Agent or Firm:
SUENARI, Mikio (JP)
End 成 Mikio (JP)
End 成 Mikio (JP)
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