Title:
Steel for suspension springs and their manufacturing method
Document Type and Number:
Japanese Patent JP6338012
Kind Code:
B2
Abstract:
Steel for a suspension spring including, as a chemical composition, by % by mass: C: more than 0.40% and 0.65% or less; Si: 1.00% to 3.50%; Mn: more than 2.00% and 3.00% or less; Cr: 0.01% to 2.00%; V: 0.02% to 0.50%; P: 0.020% or less; S: 0.020% or less: N: 0.0100% or less; and a remainder of Fe and impurities, in which Kf is 280 or more, in which a structure contains a tempered martensite of which an area ratio is 90% or more, in which a Fe-based carbide precipitated in the tempered martensite is a cementite, and in which an average of an area ratios of prior austenite grains which stretch in a longitudinal direction of the steel and of which an aspect ratio exceeds 3.0, is 80% or more in a case of depths of 0.1 mm, 0.2 mm, and 0.3 mm in a sheet thickness direction from a surface of the steel.
Inventors:
Manabu Kubota
Banno Kou City
Keisuke Chiba
Ryuichi Seki
Banno Kou City
Keisuke Chiba
Ryuichi Seki
Application Number:
JP2017505392A
Publication Date:
June 06, 2018
Filing Date:
March 10, 2016
Export Citation:
Assignee:
Nippon Steel & Sumitomo Metal Corporation
International Classes:
C22C38/00; C21D8/06; C22C38/58
Domestic Patent References:
| JP2000256741A | ||||
| JP2013076148A | ||||
| JP2012031462A | ||||
| JP2006183137A | ||||
| JP2014019894A | ||||
| JP2014118613A |
Foreign References:
| WO2011093319A1 |
Attorney, Agent or Firm:
Masatake Shiga
Mitsuo Teramoto
Sumio Tanai
Tomoo Katsumata
Hiroshi Yamaguchi
Mitsuo Teramoto
Sumio Tanai
Tomoo Katsumata
Hiroshi Yamaguchi
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