HEAT-TREATMENT STEEL FOR HIGH-STRENGTH SPRING

Title:

HEAT-TREATMENT STEEL FOR HIGH-STRENGTH SPRING

Document Type and Number:

WIPO Patent Application WO/2007/114491

Kind Code:

A1

Abstract:

A heat-treatment steel for springs which is to be subjected to cold coiling, can combine sufficient atmospheric strength with coilability, and has a tensile strength of 2,000 MPa or higher. Through a heat treatment after spring formation, the steel can heighten performances required of springs. The heat-treatment steel for high-strength springs is characterized by containing, in terms of mass%, 0.4-0.9% C, 1.0-3.0% Si, 0.1-2.0% Mn, and 0.1-1.0%, excluding 0.1%, V, the amount of N being 0.007% or less and the remainder being iron and unavoidable impurities. It is further characterized in that after the heat treatment, a subsequent extraction residue analysis gives results which satisfy the relationship [amount of V present in filtrate resulting from filtration through 0.2-µm filter (mass%)]≥[amount of V contained in steel (mass%)]Œ0.4.

Inventors:

HASHIMURA MASAYUKI (JP)
OCHI TATSUROU (JP)
KISU TAKAYUKI (JP)
HAGIWARA HIROSHI (JP)

Application Number:

PCT/JP2007/057625

Publication Date:

October 11, 2007

Filing Date:

March 29, 2007

Export Citation:

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Assignee:

NIPPON STEEL CORP (JP)
HASHIMURA MASAYUKI (JP)
OCHI TATSUROU (JP)
KISU TAKAYUKI (JP)
HAGIWARA HIROSHI (JP)

International Classes:

C22C38/00; C21D9/52; C22C38/12; C22C38/60; F16F1/02

Foreign References:

JPH10287958A	1998-10-27
JPH05195153A	1993-08-03
JPH05331597A	1993-12-14

Other References: