JP3542489B2 - High-strength extra-fine steel wire with excellent fatigue properties - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は、スチールタイヤコード、スチールベルトコード等の素線として使用され、引張強さが３５００MPa 以上である疲労特性の優れた高強度極細鋼線に関するものである。
【０００２】
【従来の技術】
軽量化などのために極細鋼線に対する高強度化の要求は一段と高まっている。従来、自動車用タイヤ、産業用各種ベルト類などの補強用に使用されている極細鋼線は、高炭素鋼の熱間圧延線材から中間伸線、パテンティング処理を繰り返し所定の線径にした後、最終パテンティング処理を行い、伸線加工性およびゴムとの接着性を向上させるめっき処理を施し所定の線径まで湿式伸線加工することにより製造される。例えばスチールタイヤコードは、上記のように製造される素線を最終的にダブルツイスタなどの撚り線機を用いて撚り線加工することによって製造される。
【０００３】
上記のような製造工程において、極細鋼線の高強度化を図るためには、最終パテンティング処理後の素線強度を上げるか、最終の伸線加工歪を増加させる必要がある。ところが、最終パテンティング処理後の素線強度ないしは伸線加工歪を増加させて極細鋼線の高強度化を図っても、極細鋼線の疲労特性は向上せず、むしろ劣化するという問題点があり、極細鋼線の高強度化を阻害する要因の一つであった。
【０００４】
これに対して極細鋼線の疲労特性を向上させる手段として、例えば特開平２−１７９３３３号公報には極細鋼線にショットピーニング処理を適用する技術が開示されており、極細線表面層の引張残留応力を圧縮残留応力に改善して耐疲労性の高い極細鋼線を製造する方法が提案されている。本発明者らの詳細な試験によれば、ショットピーニング処理によって、極細鋼線表面の引張残留応力を圧縮残留応力に改善することは可能であるが、圧縮残留応力に変えるためには非常に強いショットピーニング処理が必要である。このようなショットピーニング処理を行うと、伸線加工によって非常に薄くなった極細鋼線表層のブラスめっき層が剥離してしまい、ゴムとの密着性が劣化するという問題点が生じ、極細鋼線の疲労特性を改善するためには限界があった。
【０００５】
【発明が解決しようとする課題】
本発明は上記の如き実状に鑑みなされたものであって、すなわち圧縮残留応力に変えるために、強いショットピーニングすると、ブラスめっき層が剥離して、鋼線とゴムとの密着性の劣化が生じ、疲労特性改善に限界があったが、これを解決して、線径が０．０５〜０．４mmで引張強さが３５００ MPa 以上である疲労特性の優れた高強度極細鋼線を提供することを目的とするものである。
【０００６】
【課題を解決するための手段】
本発明者らは高強度極細鋼線の疲労特性に及ぼす影響因子について種々解析した結果、強加工されたパーライト組織中における極微量水素が鋼線の疲労寿命に著しい影響を与えることを見い出した。すなわち、強度が高い極細鋼線中に微量水素が存在すると疲労特性が劣化し、高強度極細鋼線の疲労強度を高めるためには水素量を低減させることが重要であるという全く新たな事実を見い出した。
【０００７】
以上の新知見に基づき、強加工したパーライト組織中の水素量を制御すれば、高強度極細鋼線の疲労特性を向上させることが出来るとの結論に達し本発明をなしたものである。
本発明は以上の知見に基づいてなされたものであって、その要旨とするところは、質量％で、
Ｃ：０．８０〜１．１０％、 Ｓｉ：０．０５〜２．０％、
Ｍｎ：０．２〜２．０％、
を含有する鋼線、あるいは更に、
Ｃｒ：０．０５〜１．０％、 Ｎｉ：０．１〜１．０％、
Ｖ：０．０１〜０．５％、 Ｎｂ：０．００１〜０．１％、
の１種または２種以上を含み、ともに残部はＦｅ及び不可避的不純物からなる鋼線において、伸線加工されたパーライト組織を有し、線径が０．０５〜０．４ mm で引張強さが３５００ MPa 以上で、かつ室温から３００℃に加熱する際に放出される水素量が０．５ppm 以下であることを特徴とする疲労特性の優れた高強度極細鋼線にある。
【０００８】
【発明の実施の形態】
以下に本発明の限定理由について詳細に説明する。
はじめに、本発明の化学成分限定理由について述べる。
Ｃ：
Ｃはパテンティング処理後の引張強さの増加および伸線加工硬化率を高める効果があり、より少ない伸線加工歪で極細鋼線の引張強さを高めることができる。Ｃが０．８０％未満では本発明で目的とする３５００MPa 以上の高強度の極細鋼線を製造することが困難となり、一方、１．１０％を越えるとパテンティング処理時に初析セメンタイトがオーステナイト粒界に析出して伸線加工性が劣化し伸線加工工程あるいは撚り線加工工程で断線が頻発するため、本発明ではＣを０．８０〜１．１０％の範囲に限定した。
【０００９】
Ｓｉ：
Ｓｉはパーライト中のフェライトを強化させるためと鋼の脱酸のために有効な元素である。Ｓｉが０．０５％未満では上記の効果が期待できない。一方、２．０％を越えると伸線加工性に対して有害な硬質のＳｉＯ2 系介在物が発生し易くなるため、０．０５〜２．０％の範囲に制限する。
【００１０】
Ｍｎ：
Ｍｎは脱酸、脱硫のために必要であるばかりでなく、鋼の焼入性を向上させパテンティング処理後の引張強さを高めるために有効な元素である。Ｍｎが０．２％未満では上記の効果が得られず、一方、２．０％を越えると上記の効果が飽和し、さらにパテンティング処理時のパーライト変態を完了させるための処理時間が長くなり過ぎて生産性が低下するため、本発明では０．２〜２．０％の範囲に限定した。
【００１１】
本発明による高強度極細鋼線においては、上記の元素に加えて、更にＣｒ：０．０５〜１．０％、Ｎｉ：０．１〜１．０％、Ｖ：０．０１〜０．５％、Ｎｂ：０．００１〜０．１％の範囲で１種または２種以上を含有することができる。
Ｃｒ：
Ｃｒはパーライトのセメンタイト間隔を微細化しパテンティング処理後の引張強さを高めるとともに特に伸線加工硬化率を向上させる有効な元素であるが、０．０５％未満では前記作用の効果が少なく、一方、１．０％を越えるとパテンティング処理時のパーライト変態終了時間が長くなり生産性が低下するため、本発明では０．０５〜１．０％の範囲に限定した。
【００１２】
Ｎｉ：
Ｎｉはパテンティング処理時に変態生成するパーライトを伸線加工性の良好なものにする作用を有する。この作用は０．１％未満では上記の効果が得られず、１．０％を越えても添加量に見合うだけの効果が少ないため、１．０％を上限とした。
【００１３】
Ｖ：
Ｖはパーライトのセメンタイト間隔を微細化し、パテンティング処理後の引張強さを高める効果がある。この効果は０．０１％未満では不十分であり、一方、０．５％を越えると効果が飽和するため、本発明では０．０１〜０．５％の範囲に制限した。
【００１４】
Ｎｂ：
ＮｂはＶと同様にパーライトのセメンタイト間隔を微細化し、パテンティング処理後の引張強さを高める効果がある。０．００１％未満では不十分であり、一方、０．１％を越えて添加しても効果が飽和するため、本発明では０．００１〜０．１％の範囲に制限した。
【００１５】
他の元素は特に限定しないが、Ｐ：０．０１５％以下、Ｓ：０．０１５％以下、Ｎ：０．００７０％以下が望ましい範囲である。
また、Ａｌは０．００５％を越えると鋼中の介在物の中で最も硬質なＡｌ2 Ｏ3 系介在物が生成し易くなり、伸線加工あるいは撚り線加工の際の断線原因となるため、０．００５％以下が好ましい範囲である。
【００１６】
次に、本発明で目的とする高強度極細鋼線の疲労特性を向上させる上で極めて重要となる鋼線中の水素量の限定理由について述べる。
まず、極細鋼線中の水素量は、ガスクロマトグラフを用いて昇温分析法によって測定することができる。例えば、図１は１００℃／hrの昇温速度で加熱した場合の温度に対する水素放出速度曲線である。図１から水素量を求めることができる。図１において、３００℃以下の温度域で鋼線中から放出される水素が疲労特性に悪影響を及ぼす水素であり、３００℃を越えて放出される水素は常温での疲労特性に対して影響を及ぼさない。従って、本発明では室温から３００℃の温度域で放出される水素量について限定している。また、ブラスめっきのようなめっきを施している極細鋼線では、めっき中に水素が多量に存在している場合が多いため、めっきを除去してから水素量を測定している。
【００１７】
図２は、引張強さが３６５４MPa と４１５１MPa の極細鋼線に関して、水素量（室温から３００℃に加熱される際に放出される水素量）と疲労強度の関係について解析した一例を示す。同図から明らかなように、水素量が０．５ppm を越えると疲労強度が著しく低下することがわかる。従って、水素量の上限値を０．５ppm に制限した。なお、極細鋼線の強度が高くなると同一の水素量でも、疲労寿命が低下しやすいことから、０．３ppm 以下の水素量がより好ましい条件である。また、めっきを施している極細鋼線では、めっき中に水素が存在していると疲労特性が劣化し易いことから、めっき中の水素量、すなわち室温から３００℃に加熱される際に放出される水素量も０．５ppm 以下にすることがより好ましい範囲である。
【００１８】
ここで、極細鋼線中の水素量を０．５ppm 以下に制御するためには、最終パテンティング処理以降の製造工程に下記のＡ〜Ｆの製造方法を採用することで達成できる。Ａ〜Ｆの製造条件の中で、Ｄ，Ｆが特に重要な技術である。このため、製造条件としてＤ，Ｆのいずれかあるいは両方の工程を必ず取り入れることが必須である。
【００１９】
Ａ：パテンティング処理時のオーステナイト化加熱温度が高くなるほど、雰囲気から鋼線に侵入する水素量が多くなるため、オーステナイト化加熱温度を出来る限り低くする。好ましい加熱温度は、Ａｃcm＋２０℃〜Ａｃcm＋１００℃の温度範囲である。
Ｂ：パテンティング処理時のオーステナイト化加熱雰囲気中の水分あるいは水素ガスが多いと、雰囲気から鋼線に侵入する水素量が多くなる。このため、加熱雰囲気中の水分あるいは水素ガスを体積％で２％以下の雰囲気に制御する。
【００２０】
ＡあるいはＢもしくは両者の手段によって、パテンティング処理時に雰囲気から鋼線に侵入する水素量を０．５ppm 以下にすることが好ましい加熱条件である。
Ｃ：パテンティング処理後のスケール除去のための酸洗は、酸濃度、酸洗時間あるいは電解酸洗を行う場合は電流密度等を制御することによって、鋼線中に侵入する水素量を低下させる。酸洗の工程で侵入する水素量は、０．５ppm 以下が好ましい条件である。
【００２１】
Ｄ：酸洗処理後に水素を放出させるためのベーキング処理を行う。ベーキング処理は、１００〜５００℃の温度範囲で０．１〜３００分間の処理が好ましい条件である。
Ｅ：電気めっきを施す場合は、電流効率が１００％近い条件でめっきを行う。電気めっきの際に鋼線に侵入する水素量を０．５ppm 以下にすることが好ましい条件である。
【００２２】
Ｆ：めっき処理後は、水素放出のためのベーキング処理を行う。ベーキング処理は、５０〜４００℃の温度範囲で０．１〜３００分間の処理が好ましい条件である。
【００２３】
【実施例】
以下、実施例により本発明の効果をさらに具体的に説明する。
表１に供試材の化学組成を示す。これらの供試材を熱間圧延により線径５．５mmにし、一次伸線加工、一次パテンティング処理、二次伸線加工を行った。その後、最終パテンティング処理、引き続きブラスめっき処理を行い、伸線速度６００ｍ／分の条件で湿式伸線加工を行った。
【００２４】
【表１】
表２および表３に極細鋼線の製造条件（前述のＡ〜Ｆ条件）および引張強さ、水素量、疲労強度を示す。極細線中の水素量はブラスめっきを除去した後、ガスクロマトグラフを用いて昇温分析（試料の加熱速度は１００℃／hr）によって測定し、室温から３００℃の温度範囲で放出される水素量を測定した。また、疲労強度は、温度：２０〜２５℃、湿度：５０〜６０％の環境での１０7 サイクルの回転曲げ疲労試験で評価した結果である。
【００２６】
【表２】
【表３】
表２および表３の試験No. １〜１０が本発明例で、試験No. １１〜１８が比較例である。同表に見られるように本発明例の極細鋼線は水素量が０．５ppm 以下に制御されているために、いずれの鋼線も疲労強度が高いことがわかる。
これに対して、比較例であるNo. １１〜１７はいずれも従来の極細鋼線である。水素量が高いために、疲労強度が本発明例に比べ低い。また、比較例であるNo. １８はＣ含有量が高すぎるためにパテンティング処理時に初析セメンタイトが析出した例である。この結果、伸線加工性が劣化し、伸線加工時に断線が頻発したものである。
【００２９】
【発明の効果】
以上の実施例からも明かなように、本発明は引張強さが３５００MPa 以上の高強度極細鋼線の疲労特性を向上させる手段として、鋼線中の水素量を制御することが極めて有効であることを見出し、疲労特性の優れた高強度極細鋼線を実現したものであり、産業上の効果は極めて顕著なものがある。
【図面の簡単な説明】
【図１】本発明に係る極細鋼線の水素放出プロファイルについて解析した一例を示す図である。
【図２】本発明に係る極細鋼線の水素量と疲労強度の関係について解析した一例を示す図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-strength ultra-fine steel wire used as a strand of a steel tire cord, a steel belt cord or the like and having excellent fatigue properties and a tensile strength of 3500 MPa or more.
[0002]
[Prior art]
The demand for higher strength of ultra-fine steel wire for weight reduction and the like is further increasing. Conventionally, ultra-fine steel wire used for reinforcement of automobile tires, industrial belts, etc., is obtained by repeating intermediate drawing and patenting from hot-rolled high carbon steel wire to a predetermined wire diameter. It is manufactured by performing a final patenting process, performing a plating process for improving wire drawing workability and adhesion to rubber, and performing wet wire drawing to a predetermined wire diameter. For example, a steel tire cord is manufactured by finally twisting a strand manufactured as described above using a twisting machine such as a double twister.
[0003]
In the manufacturing process as described above, in order to increase the strength of the ultrafine steel wire, it is necessary to increase the wire strength after the final patenting treatment or to increase the final drawing strain. However, even if the strength of the ultrafine steel wire is increased by increasing the wire strength or drawing strain after the final patenting process, the fatigue characteristics of the ultrafine steel wire do not improve, but rather deteriorate. This was one of the factors that hindered the strengthening of ultrafine steel wires.
[0004]
On the other hand, as a means for improving the fatigue characteristics of an ultrafine steel wire, for example, Japanese Patent Application Laid-Open No. 2-179333 discloses a technique in which shot peening is applied to an ultrafine steel wire. There has been proposed a method of manufacturing a fine steel wire having high fatigue resistance by improving stress to compressive residual stress. According to the detailed tests of the present inventors, it is possible to improve the tensile residual stress on the surface of the ultrafine steel wire to the compressive residual stress by the shot peening treatment, but it is very strong to convert it to the compressive residual stress. Shot peening is required. When such a shot peening treatment is performed, the brass plating layer on the surface layer of the ultrafine steel wire, which has become extremely thin due to the wire drawing, is peeled off, causing a problem that the adhesion to rubber is deteriorated. There were limits to improving the fatigue properties of steel.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above situation, that is, in order to change to compressive residual stress, when strong shot peening, the brass plating layer peels off, and the adhesion between the steel wire and the rubber deteriorates. There is a limit in improving the fatigue properties, but by solving this, there is provided a high-strength ultrafine steel wire having excellent fatigue properties, having a wire diameter of 0.05 to 0.4 mm and a tensile strength of 3500 MPa or more. It is intended for that purpose.
[0006]
[Means for Solving the Problems]
The present inventors have conducted various analyzes on the influencing factors on the fatigue properties of a high-strength ultrafine steel wire, and as a result, have found that a trace amount of hydrogen in a strongly-worked pearlite structure has a significant effect on the fatigue life of the steel wire. In other words, the fact that a small amount of hydrogen is present in a high-strength ultrafine steel wire deteriorates the fatigue properties, and a completely new fact that it is important to reduce the amount of hydrogen to increase the fatigue strength of a high-strength ultrafine steel wire. I found it.
[0007]
Based on the above new findings, the present inventors have concluded that controlling the amount of hydrogen in the pearlite structure that has been strongly worked can improve the fatigue characteristics of a high-strength ultrafine steel wire, and made the present invention.
The present invention was made based on the above findings, it is an gist, in mass%,
C: 0.80 to 1.10%, Si: 0.05 to 2.0%,
Mn: 0.2-2.0%,
Or a steel wire containing
Cr: 0.05 to 1.0%, Ni: 0.1 to 1.0%,
V: 0.01-0.5%, Nb: 0.001-0.1%,
A steel wire composed of Fe and unavoidable impurities, the rest of which has a drawn pearlite structure, a wire diameter of 0.05 to 0.4 mm , and a tensile strength of Is not less than 3500 MPa , and the amount of hydrogen released upon heating from room temperature to 300 ° C. is not more than 0.5 ppm.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the reasons for limitation of the present invention will be described in detail.
First, the reasons for limiting the chemical components of the present invention will be described.
C:
C has an effect of increasing the tensile strength after the patenting treatment and increasing the rate of wire drawing work hardening, and can increase the tensile strength of the ultrafine steel wire with less wire drawing strain. If C is less than 0.80%, it is difficult to produce a high-strength ultra-fine steel wire of 3500 MPa or more intended in the present invention, while if it exceeds 1.10%, pro-eutectoid cementite becomes austenitic grains during patenting treatment. In the present invention, C is limited to the range of 0.80 to 1.10%, because it precipitates in the field and deteriorates the wire drawing processability and frequently causes disconnection in the wire drawing process or the stranded wire process.
[0009]
Si:
Si is an element effective for strengthening ferrite in pearlite and for deoxidizing steel. If the Si content is less than 0.05%, the above effects cannot be expected. On the other hand, if it exceeds 2.0%, hard SiO 2 -based inclusions harmful to wire drawing workability are likely to be generated, so the content is limited to the range of 0.05 to 2.0%.
[0010]
Mn:
Mn is an element effective not only for deoxidation and desulfurization but also for improving the hardenability of steel and increasing the tensile strength after the patenting treatment. If Mn is less than 0.2%, the above effects cannot be obtained. On the other hand, if Mn exceeds 2.0%, the above effects are saturated, and the processing time for completing the pearlite transformation during the patenting process becomes longer. Therefore, the productivity is reduced, so that the content is limited to the range of 0.2 to 2.0% in the present invention.
[0011]
In the high-strength ultrafine steel wire according to the present invention, in addition to the above elements, Cr: 0.05 to 1.0%, Ni: 0.1 to 1.0%, V: 0.01 to 0.5 %, Nb: One or more of them may be contained in the range of 0.001 to 0.1%.
Cr:
Cr is an effective element for refining the cementite spacing of pearlite, increasing the tensile strength after the patenting treatment, and particularly improving the wire work hardening rate. If it exceeds 1.0%, the pearlite transformation end time during the patenting process becomes longer and the productivity decreases, so in the present invention, it is limited to the range of 0.05 to 1.0%.
[0012]
Ni:
Ni has an effect of making pearlite generated by transformation during the patenting process excellent in wire drawing workability. If this effect is less than 0.1%, the above effect cannot be obtained, and if it exceeds 1.0%, the effect corresponding to the added amount is small, so the upper limit was made 1.0%.
[0013]
V:
V has the effect of reducing the pearlite cementite spacing and increasing the tensile strength after patenting. If this effect is less than 0.01%, the effect is insufficient, while if it exceeds 0.5%, the effect is saturated. Therefore, in the present invention, the effect is limited to the range of 0.01 to 0.5%.
[0014]
Nb:
Nb, like V, has the effect of reducing the pearlite cementite spacing and increasing the tensile strength after patenting. If it is less than 0.001%, it is not sufficient. On the other hand, if it exceeds 0.1%, the effect is saturated. Therefore, in the present invention, it is limited to the range of 0.001 to 0.1%.
[0015]
Other elements are not particularly limited, but P: 0.015% or less, S: 0.015% or less, and N: 0.0070% or less are desirable ranges.
On the other hand, if the content of Al exceeds 0.005%, the hardest Al 2 O 3 -based inclusion among the inclusions in the steel is likely to be generated, which causes a disconnection in wire drawing or stranded wire processing. , 0.005% or less is a preferable range.
[0016]
Next, the reason for limiting the amount of hydrogen in the steel wire, which is extremely important for improving the fatigue properties of the high-strength ultrafine steel wire intended in the present invention, will be described.
First, the amount of hydrogen in the ultrafine steel wire can be measured by a temperature rising analysis method using a gas chromatograph. For example, FIG. 1 is a hydrogen release rate curve with respect to temperature when heating is performed at a rate of 100 ° C./hr. The amount of hydrogen can be determined from FIG. In FIG. 1, hydrogen released from the steel wire in a temperature range of 300 ° C. or less is hydrogen that has a bad effect on fatigue characteristics, and hydrogen released over 300 ° C. has an influence on fatigue characteristics at room temperature. Has no effect. Therefore, in the present invention, the amount of hydrogen released in a temperature range from room temperature to 300 ° C. is limited. In addition, in the case of ultra-fine steel wire plated by brass plating, a large amount of hydrogen is often present in the plating, so the amount of hydrogen is measured after removing the plating.
[0017]
FIG. 2 shows an example of analyzing the relationship between the amount of hydrogen (the amount of hydrogen released when heated from room temperature to 300 ° C.) and the fatigue strength of ultrafine steel wires having tensile strengths of 3654 MPa and 4151 MPa. As is apparent from the figure, when the amount of hydrogen exceeds 0.5 ppm, the fatigue strength is significantly reduced. Therefore, the upper limit of the amount of hydrogen was limited to 0.5 ppm. In addition, since the fatigue life tends to be reduced even with the same amount of hydrogen when the strength of the ultrafine steel wire is increased, a hydrogen amount of 0.3 ppm or less is a more preferable condition. In addition, in the case of plated ultrafine steel wire, if hydrogen is present in the plating, the fatigue properties are likely to deteriorate, so the amount of hydrogen in the plating, that is, released when heated from room temperature to 300 ° C. It is a more preferable range that the amount of hydrogen is set to 0.5 ppm or less.
[0018]
Here, in order to control the amount of hydrogen in the ultrafine steel wire to 0.5 ppm or less, it can be achieved by employing the following manufacturing methods A to F in the manufacturing process after the final patenting process. Among the manufacturing conditions A to F, D and F are particularly important technologies. For this reason, it is essential that either or both of the steps D and F be incorporated as manufacturing conditions.
[0019]
A: The higher the austenitizing heating temperature during the patenting treatment, the greater the amount of hydrogen that enters the steel wire from the atmosphere, and therefore the lower the austenitizing heating temperature. A preferable heating temperature is a temperature range of Accm + 20 ° C. to Accm + 100 ° C.
B: If the amount of moisture or hydrogen gas in the austenitizing heating atmosphere during the patenting process is large, the amount of hydrogen that enters the steel wire from the atmosphere increases. For this reason, the moisture or hydrogen gas in the heating atmosphere is controlled to an atmosphere of 2% or less by volume%.
[0020]
It is a preferable heating condition that the amount of hydrogen entering the steel wire from the atmosphere during the patenting treatment by the means A or B or both is set to 0.5 ppm or less.
C: Pickling for scale removal after the patenting treatment reduces the amount of hydrogen penetrating into the steel wire by controlling the acid concentration, the pickling time, or the current density when electrolytic pickling is performed. . The amount of hydrogen entering in the pickling step is preferably 0.5 ppm or less.
[0021]
D: Baking treatment for releasing hydrogen is performed after the pickling treatment. The baking treatment is preferably performed at a temperature of 100 to 500 ° C. for 0.1 to 300 minutes.
E: When performing electroplating, plating is performed under conditions where current efficiency is close to 100%. It is a preferable condition that the amount of hydrogen entering the steel wire during electroplating is set to 0.5 ppm or less.
[0022]
F: After the plating process, a baking process for releasing hydrogen is performed. The baking treatment is preferably performed at a temperature of 50 to 400 ° C. for 0.1 to 300 minutes.
[0023]
【Example】
Hereinafter, the effects of the present invention will be described more specifically with reference to examples.
Table 1 shows the chemical composition of the test materials. These test materials were hot-rolled to a wire diameter of 5.5 mm and subjected to primary drawing, primary patenting, and secondary drawing. After that, a final patenting process and a subsequent brass plating process were performed, and wet drawing was performed at a drawing speed of 600 m / min.
[0024]
[Table 1]
Tables 2 and 3 show the manufacturing conditions (the above-mentioned A to F conditions), tensile strength, hydrogen content, and fatigue strength of the ultrafine steel wire. After removing the brass plating, the amount of hydrogen in the ultrafine line is measured by temperature rise analysis using a gas chromatograph (heating rate of the sample is 100 ° C / hr), and the amount of hydrogen released in the temperature range from room temperature to 300 ° C Was measured. Further, the fatigue strength is a result evaluated by a 10 7 cycle rotational bending fatigue test in an environment of temperature: 20 to 25 ° C. and humidity: 50 to 60%.
[0026]
[Table 2]
[Table 3]
Test Nos. 1 to 10 in Tables 2 and 3 are examples of the present invention, and Test Nos. 11 to 18 are comparative examples. As can be seen from the table, since the ultrafine steel wire of the present invention is controlled to have a hydrogen content of 0.5 ppm or less, all the steel wires have high fatigue strength.
On the other hand, Nos. 11 to 17 as comparative examples are all conventional ultrafine steel wires. Since the amount of hydrogen is high, the fatigue strength is lower than that of the present invention. No. 18, which is a comparative example, is an example in which proeutectoid cementite was precipitated during the patenting treatment because the C content was too high. As a result, wire drawing workability was deteriorated, and disconnection frequently occurred during wire drawing.
[0029]
【The invention's effect】
As is apparent from the above examples, the present invention is extremely effective as a means for improving the fatigue characteristics of a high-strength ultrafine steel wire having a tensile strength of 3500 MPa or more, by controlling the amount of hydrogen in the steel wire. Thus, the present invention has realized a high-strength ultrafine steel wire having excellent fatigue properties, and has extremely remarkable industrial effects.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of analyzing a hydrogen release profile of an ultrafine steel wire according to the present invention.
FIG. 2 is a diagram showing an example of analyzing the relationship between the hydrogen content and the fatigue strength of the ultrafine steel wire according to the present invention.
Claims (2)
Ｃ：０．８０〜１．１０％、
Ｓｉ：０．０５〜２．０％
Ｍｎ：０．２〜２．０％、
残部はＦｅおよび不可避的不純物からなる鋼線において、伸線加工されたパーライト組織を有し、線径が０．０５〜０．４ｍｍで引張強さが３５００ＭＰａ以上で、かつ室温から３００℃に加熱する際に放出される水素量が０．５ｐｐｍ以下であることを特徴とする疲労特性の優れた高強度極細鋼線。In mass%,
C: 0.80 to 1.10%,
Si: 0.05 to 2.0%
Mn: 0.2-2.0%,
The remainder is a steel wire composed of Fe and unavoidable impurities, has a drawn pearlite structure, a wire diameter of 0.05 to 0.4 mm, a tensile strength of 3500 MPa or more , and is heated from room temperature to 300 ° C. A high-strength ultra-fine steel wire having excellent fatigue properties, characterized in that the amount of hydrogen released during the process is 0.5 ppm or less.
Ｃｒ：０．０５〜２．０％、
Ｎｉ：０．１〜１．０％、
Ｖ：０．０１〜０．５％、
Ｎｂ：０．００１〜０．１％、
の１種または２種以上を含有することを特徴とする請求項１記載の疲労特性の優れた高強度極細鋼線。In mass%,
Cr: 0.05 to 2.0%,
Ni: 0.1 to 1.0%,
V: 0.01 to 0.5%,
Nb: 0.001 to 0.1%,
The high-strength ultra-fine steel wire having excellent fatigue properties according to claim 1, comprising one or more of the following.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05983598A JP3542489B2 (en) | 1998-03-11 | 1998-03-11 | High-strength extra-fine steel wire with excellent fatigue properties |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05983598A JP3542489B2 (en) | 1998-03-11 | 1998-03-11 | High-strength extra-fine steel wire with excellent fatigue properties |
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| Publication Number | Publication Date |
|---|---|
| JPH11256274A JPH11256274A (en) | 1999-09-21 |
| JP3542489B2 true JP3542489B2 (en) | 2004-07-14 |
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|---|---|---|---|
| JP05983598A Expired - Lifetime JP3542489B2 (en) | 1998-03-11 | 1998-03-11 | High-strength extra-fine steel wire with excellent fatigue properties |
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| JP (1) | JP3542489B2 (en) |
Cited By (1)
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| CN102851433A (en) * | 2012-08-29 | 2013-01-02 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for controlling content of nitrogen in semi-steel smelted tire cord steel or hard wire steel |
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| US6699335B2 (en) | 2000-11-15 | 2004-03-02 | Nsk Ltd. | Machine part |
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| FR2960556B3 (en) | 2010-05-31 | 2012-05-11 | Arcelormittal Wire France | HIGH-STRENGTH STEEL-SHAPED WIRE FOR MECHANICAL RESISTANT TO HYDROGEN FRAGILIZATION |
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1998
- 1998-03-11 JP JP05983598A patent/JP3542489B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102851433A (en) * | 2012-08-29 | 2013-01-02 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for controlling content of nitrogen in semi-steel smelted tire cord steel or hard wire steel |
| CN102851433B (en) * | 2012-08-29 | 2014-06-25 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for controlling content of nitrogen in semi-steel smelted tire cord steel or hard wire steel |
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| Publication number | Publication date |
|---|---|
| JPH11256274A (en) | 1999-09-21 |
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