Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho

Suncall Corporation

Kabushiki Kaisha Kobe Seiko Sho (kobe Steel, Ltd.)

Nhk Spring Co., Ltd.

Ascometal

Asco Industries

Shinko Wire Company, Ltd.

Ascometal France Holding Sas

Nao Yoshihara

Nobuhiko Ibaraki

Hiroshi Oura

Sumie Suda

Koji Harada

Shigetsugu Yoshida

Tomonobu Ishida

Toshiki Sato

Takeshi Kuroda

Hiroshi Yaguchi

Wataru Urushihara

Takuya Kochi

Tomokazu Masuda

Atsushi Inada

Tomotada Maruo

Shoji Miyazaki

Julie Mougin

Kei Masumoto

Fujio Koizumi

Tetsuo Jinbo

Sayaka Nagamatsu

Akito Suzuki

Shuhei Kitamura

Kengo Tsurugai

Hirokazu Inoue

Atsuhiko Takeda

Katsuya Takaoka

Takayuki Naito

Fumio Yamamoto

Toshio Maehata

Yoshiharu Yamamoto

Kazuhisa Kawata

Jacques Languillaume

The present invention provides a steel material, such as a high-strength spring, that has excellent fatigue properties, and, more specifically, a steel material, such as the high-strength spring, that can improve the fatigue properties in a high-strength region more easily, without increasing an alloy cost. The steel material includes, in percent by mass, C: 0.5 to 1.0%, Si: 1.5 to 2.50%, Mn: 0.5 to 1.50%, P: more than 0% to 0.020% or less, S: more than 0% to 0.020% or less, Cr: more than 0% to 0.2% or less, Al: more than 0% to 0.010% or less, N: more than 0% to 0.0070% or less, and O: more than 0% to 0.0040% or less, and the balance consisting of iron and inevitable impurities, wherein Cr and Si contents satisfy a formula of Cr&#xd7;Si&#x2264;0.20, a ratio of tempered martensite in a steel microstructure is 80% or more by area, and a number density of particles of Cr-containing carbide or carbonitride having a circle-equivalent diameter of 50 nm or more in the steel microstructure is 0.10 particles/&#x3bc;mor less.

High-strength steel material having excellent fatigue properties

This high carbon steel wire rod, which has excellent drawability in addition to high strength required for a wire rod, contains 0.6-1.5% of C, 0.1-1.5% of Si, 0.1-1.5% of Mn, 0.02% or less of P (excluding 0%), 0.02% or less of S (excluding 0%), 0.03-0.12% of Ti, 0.001-0.01% of B and 0.001-0.005% of N, with solid-solved B being 0.0002% or more, solid-solved N being 0.0010% or less, and the balance being made up of iron and inevitable impurities. In addition, the content of Ti solid-solved in the steel is 0.002% by mass or more, and the content of Ti that formed carbides is 0.020% by mass or more.

High carbon steel wire rod having excellent drawability

A high-strength spring steel wire is provided which secures excellent hydrogen embrittlement resistance even when the adding amount of alloy elements is suppressed, and has 80 area % or more of tempered martensite and 1,900 MPa or more of the tensile strength, in which a predetermined chemical composition is satisfied, with C and Si satisfying the relation of the expression (1) below, with prior austenite grain size number being No. 10 or more, and with the hydrogen absorption amount being 14.0 ppm or more.0.73%&#x2264;[C]+[Si]/8&#x2264;0.90%&#x2003;&#x2003;(1)where [C] and [Si] express the content (mass %) of C and Si respectively.

High-strength spring steel wire with excellent hydrogen embrittlement resistance, manufacturing process therefor, and high-strength spring

Disclosed is a cold formable spring steel wire excellent in cold cutting capability and fatigue properties, in which the steel wire satisfies given composition, has an average globular carbide particle size [&#x221a;(ab)]:1.0 &#x3bc;m or less with aspect ratio (a/b, a: major axis of carbide, b: minor axis of carbide) being 2 or less, a ratio (area %) of the globular carbide in the steel: (0.1 to 3)&#xd7;amount (mass %) of C in the steel, an amount (mass %) of Cr in the globular carbide: [0.4&#xd7;amount (mass %) of Cr in the steel] or less, hardenability factor (Dic): between 110 mm and 450 mm, and tensile stress of 2000 MPa or more.

Cold formable spring steel wire excellent in cold cutting capability and fatigue properties and manufacturing process thereof

A technique with which air blast cooling can be used to produce a high-strength steel wire material that achieves uniform high strength and high ductility, even when cold drawn; a high-strength steel wire produced from this high-strength steel wire material; and a zinc-plated high-strength steel wire. This high-strength steel wire material includes 0.80-1.3% of C, 0.1-1.5% of Si, 0.1-1.5% of Mn, more than 0% but not more than 0.03% of P, more than 0% but not more than 0.03% of S, 0.0005-0.01% of B, 0.01-0.10% of Al, and 0.001-0.006% of N, the remainder being iron and unavoidable impurities. The area ratio of pearlite in the structure of the high-strength steel wire material is at least 90%. The average grain size number (P) of pearlite nodules and the standard deviation (P&#x3c3;) thereof respectively satisfy formula (1), namely 7.0&#x2266;P&#x2266;10.0, and formula (2), namely P&#x3c3;&#x2266;0.6.

High-strength steel wire material exhibiting excellent cold-drawing properties, and high-strength steel wire

Provided is a high-carbon steel wire which gives steel wires having high strength and has excellent suitability for wiredrawing and which after being wiredrawn, has excellent fatigue properties. The high-carbon steel wire has an adequately regulated chemical composition and has a pearlite structure in an areal proportion of 90% or more. In 2,000 &#x3bc;mof the pearlite structure, the number of BN compound grains having an equivalent-circle diameter of 100 nm or more but less than 1,000 nm is 100 or less (including 0) and the number of BN compound grains having an equivalent-circle diameter of 1,000 nm or more is 10 or less (including 0).

High-carbon steel wire excellent in wire drawability and fatigue property after wiredrawing

Provided are: a steel wire rod material for a high-strength spring, which does not undergo the increase in deformation resistance arising from the increase in hardness and can exhibit good wire-drawing processability and the like even when a heat treatment, which deteriorates productivity, is eliminated or a simplified and rapid heat treatment is employed instead; a useful method for producing the steel wire rod material for a high-strength spring; a high-strength spring produced using the steel wire rod material for a high-strength spring as a material; and others. This steel wire rod material for a high-strength spring is a steel wire rod material that has been hot-rolled already, and has a texture having a specified chemical composition and mainly composed of pearlite, wherein the average value (Pave) of the pearlite nodule size numbers and the standard deviation (P&#x3c3;) of the pearlite nodule size numbers fulfill the following formulae (1) and (2), respectively:9.5&#x2266;ave&#x2266;12.0;&#x2003;&#x2003;(1)and0.2&#x2266;&#x3c3;&#x2266;0.7&#x2003;&#x2003;(2).

Steel wire rod for high-strength spring excellent in wire drawability, manufacturing method therefor, and high-strength spring

Disclosed is a spring steel, containing: C: 0.35-0.65% (the term '%' herein means 'mass %', the same is true hereinbelow), Si: 1.5-2.5%, Mn: 0.05-1%, Cr: 0.05-1.9%, P: 0.015% or less (exclusive of 0%), S: 0.015% or less (exclusive of 0%), Ti: 0.025-0.1%, Al: 0.05% or less (exclusive of 0%), and N: 0.01% or less (exclusive of 0%), wherein an amount of Ti nitride, an amount of Ti sulfide, and an amount of Ti carbide satisfy the following formulas (1), (2), and (3);[Ti]&#x2267;3.42&#xd7;[N]&#x2212;0.354&#xd7;[Al]&#x2212;0.103&#xd7;[Nb]&#x2003;&#x2003;(1)[Ti]&#x2267;1.49&#xd7;[S]&#x2003;&#x2003;(2)[Ti]&#x2267;0.015 &#x2003;&#x2003;(3),in which [Ti] represents the amount of Ti (mass %) forming Ti nitride, [Ti] represents the amount of Ti (mass %) forming Ti sulfide, [Ti] represents the amount of Ti (mass %) forming Ti carbide, and [N], [Al], [Nb], and [S] represent an amount (mass %) of each element in the steel. The spring steel of the present invention shows excellent resistance to hydrogen embrittlement.

Spring steel with excellent resistance to hydrogen embrittlement and steel wire and spring obtained from the steel

The steel wire material for a spring of the invention contains; C: 0.37-0.54%, Si: 1.7-2.30%, Mn: 0.1-1.30%, Cr: 0.15-1.1%, Cu: 0.15-0.6%, Ti: 0.010-0.1%, Al: 0.003-0.05%, and the balance including iron with inevitable impurities, wherein ferrite decarburized layer depth is 0.01 mm or less, whole decarburized layer depth is 0.20 mm or less, and fracture reduction of area is 25% or more. It alternately may contain; C: 0.38-0.47%, Si: 1.9-2.5%, Mn: 0.6-1.3%, Ti: 0.05-0.15%, Al: 0.003-0.1%, and the balance including iron with inevitable impurities, wherein ferrite decarburized layer depth is 0.01 mm or less.

Steel wire material for spring and its producing method

An object of the preset invention is to provide a spring steel wire that: shows excellent wire drawability not only when it is used as a spring steel wire for cold-winding formed into a steel spring by applying quenching and tempering treatment after wiredrawing but also when it is used as a spring steel wire for cold-winding formed into a steel spring as it is wiredrawn; and secures a spring having an excellent fatigue characteristic after the spring steel wire is formed into the spring. The spring steel wire according to the present invention is a spring steel wire excellent in fatigue characteristic and wire drawability, wherein: the contents of C, Si, Mn, Cr, Ti, B, and other elements are specified; the contents (mass %) of B, Ti, and N satisfy the expression (1) below; the amount of solid solute B is in the range of 0.0005% to 0.0040%; the remainder in the spring steel wire is composed of Fe and unavoidable impurities; and the solid solute B concentrates at the grain boundaries of pearlite nodules,0.03&#x2266;B/(Ti/3.43&#x2212;N)&#x2266;5.0&#x2003;&#x2003;(1).

Spring steel wire excellent in fatigue characteristic and wire drawability

A steel wire for a cold-formed spring according to the present invention contains a prescribed chemical component composition, wherein: a martensitic transformation start temperature Mshown by the following expression (1) is in the range from 280&#xb0; C. to 380&#xb0; C.; the austenite grain size number N of austenite grains is No. 12 or more; the grain boundary share of carbide precipitated along the austenite grain boundaries is 50% or less; the amount of retained austenite after austenitized and tempered is 20 vol. % or less; and the tensile strength is 2,000 MPa or more;=550&#x2212;361[C]&#x2212;39[Mn]&#x2212;20[Cr]&#x2003;&#x2003;(1), where [C], [Mn] and [Cr] represent the contents (mass %) of C, Mn and Cr, respectively. Such a steel wire can: secure hot-rolling formability and subsequent drawability while aiming at higher strength and higher stress; moreover exhibit excellent corrosion resistance; and obtain a spring (mainly a suspension spring for an automobile) excellent also in fatigue strength which is a basic required characteristic.

Steel wire for cold-formed spring excellent in corrosion resistance and method for producing the same

Disclosed herein is a spring wire rod excelling in fatigue characteristics. It contains TiN inclusions having a specific size defined by the ratio of each group in all the visual fields as follows: The visual field is the cross section passing through the center line of the wire rod.

Spring wire rod excelling in fatigue characteristics

A high-strength steel excellent in hydrogen embrittlement resistance is provided. The high-strength steel of the present invention excellent in hydrogen embrittlement resistance has a tensile strength of 1800 N/mmor above, contains 0.3 to 0.7% (percent by mass) C, 0.95 to 5.0% Cr, not higher than 0.6% and higher than 0% Mn, and 0.7 to 2.5% Si, and contains at least one of Mg, Ca, Sr, Ba, Li, Na and K so as to meet the following conditions: 

High-strength steel with excellent unsusceptibility to hydrogen embrittlement

Disclosed is a hard-drawn spring which exhibits fatigue strength and sag resistance equal or superior to springs produced using an oil-tempered wire. The hard-drawn spring is produced using a steel wire containing 0.5 to 0.7 mass % of C, 1.0 to 1.95 mass % of Si, 0.5 to 1.5 mass % of Mn and 0.5 to 1.5 mass % of Cr, with the balance being Fe and inevitable impurities. In the steel wire, the number of carbides having circle-equivalent diameters of 0.1 &#x3bc;m or more is 5 particles/100 &#x3bc;mor less.

Spring produced by a process comprising coiling a hard drawn steel wire excellent in fatigue strength and resistance to setting

A steel for high-strength springs contains, on the mass basis, 0.35% to 0.65% of C, 1.4% to 2.5% of Si, 0.1% to 1.0% of Mn, 2.0% or less (exclusive of 0%) of Cr, 1.0% or less (exclusive of 0%) of Ni, 1.0% or less (exclusive of 0%) of Cu, 0.020% or less (exclusive of 0%) of P, 0.020% or less (exclusive of 0%) of S, 0.006% or less (exclusive of 0%) of N:, and 0.1% or less (exclusive of 0%) of Al, with the remainder being iron and inevitable impurities, in which Wp(Fe) and W(C) satisfy the following condition: Wp(Fe)&#x3e;5&#xd7;W(C), wherein Wp(Fe) is the content of Fe (percent by mass) constituting Fe-containing precipitates in the steel; and W(C) is the carbon content (percent by mass) of the steel. The steel is excellent in cold workability and quality stability.

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Kobe, Japan

Nao Yoshihara