JP2009235523A - Oil tempered steel wire, its production method, and spring - Google Patents
Oil tempered steel wire, its production method, and spring Download PDFInfo
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- JP2009235523A JP2009235523A JP2008084682A JP2008084682A JP2009235523A JP 2009235523 A JP2009235523 A JP 2009235523A JP 2008084682 A JP2008084682 A JP 2008084682A JP 2008084682 A JP2008084682 A JP 2008084682A JP 2009235523 A JP2009235523 A JP 2009235523A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 60
- 239000010959 steel Substances 0.000 title claims abstract description 60
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 25
- 230000003746 surface roughness Effects 0.000 claims abstract description 30
- 238000005491 wire drawing Methods 0.000 claims abstract description 12
- 238000009499 grossing Methods 0.000 claims abstract description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 229910052710 silicon Inorganic materials 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims description 2
- 238000005496 tempering Methods 0.000 abstract description 8
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 31
- 230000000694 effects Effects 0.000 description 17
- 239000000126 substance Substances 0.000 description 13
- 238000000034 method Methods 0.000 description 11
- 238000005498 polishing Methods 0.000 description 11
- 230000037303 wrinkles Effects 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 238000000137 annealing Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000005121 nitriding Methods 0.000 description 6
- 238000012545 processing Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 238000005422 blasting Methods 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000006061 abrasive grain Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000009661 fatigue test Methods 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 235000013980 iron oxide Nutrition 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000005480 shot peening Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
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- Heat Treatment Of Steel (AREA)
- Springs (AREA)
- Metal Extraction Processes (AREA)
Abstract
Description
本発明は、自動車のエンジン用弁ばねなど、耐疲労性が要求されるばねに使用されるオイルテンパー線とその製造方法に関する。特に、コイリング性ならびに疲労特性に優れたオイルテンパー線とその製造方法に関する。 The present invention relates to an oil tempered wire used for a spring that requires fatigue resistance, such as a valve spring for an engine of an automobile, and a manufacturing method thereof. In particular, the present invention relates to an oil tempered wire excellent in coiling properties and fatigue characteristics and a method for producing the same.
自動車のエンジン用弁ばねに使用される鋼線としては、従来からSiCr鋼のオイルテンパー線が使用されている。 Conventionally, an oil tempered wire made of SiCr steel has been used as a steel wire used for an automobile engine valve spring.
通常、オイルテンパー線は、鋼の溶製→鋳造→圧延→パテンチング→（皮剥ぎ→焼鈍）→伸線→オイルテンパー処理を経て製造され、このようにして製造されたオイルテンパー線をばね加工（コイリング）することで、ばねが製造される。 Usually, oil tempered wire is manufactured through steel melting → casting → rolling → patenting → (peeling → annealing) → wire drawing → oil temper treatment, and the oil tempered wire thus manufactured is spring processed ( A spring is manufactured by coiling.
近年、自動車のエンジンやトランスミッションの小型軽量化が進められており、それに伴い、エンジン用弁ばねやトランスミッション用ばねに負荷される応力も増大する傾向にあるため、ばねの耐疲労性を向上させることが望まれる。このような要望に応えるためには、ばねに使用されるオイルテンパー線自体の疲労特性を改善する必要がある。 In recent years, automobile engines and transmissions have been reduced in size and weight, and along with this, the stress applied to engine valve springs and transmission springs tends to increase. Is desired. In order to meet such a demand, it is necessary to improve the fatigue characteristics of the oil tempered wire itself used in the spring.
オイルテンパー線の疲労特性を改善する技術が、例えば特許文献１に開示されている。特許文献１では、SiCr鋼のC量を増やし、更にVを添加することで、高強度化を図り、オイルテンパー線の疲労特性を向上させている。 For example, Patent Literature 1 discloses a technique for improving the fatigue characteristics of an oil tempered wire. In Patent Document 1, increasing the amount of C in SiCr steel and further adding V increases the strength and improves the fatigue characteristics of the oil tempered wire.
また、特許文献２には、オイルテンパー処理を施した後、電解研磨、化学研磨、又はショットピーニングといった表面処理を施すことにより、オイルテンパー線表面を清浄化することが記載されている。 Patent Document 2 describes that the oil tempered wire surface is cleaned by applying a surface treatment such as electrolytic polishing, chemical polishing, or shot peening after the oil temper treatment.
しかし、従来のオイルテンパー線は、コイリング性と高い疲労特性を両立することが難しい。 However, it is difficult for conventional oil tempered wires to achieve both coilability and high fatigue characteristics.
特許文献１に記載のオイルテンパー線は、鋼線を高強度化することで、疲労特性を向上させている。しかし、高強度の鋼線は、疵感受性が高く、表面の微小な疵が疲労特性に影響を及ぼすことが知られており、疲労限の向上に限界がある。 The oil tempered wire described in Patent Document 1 has improved fatigue characteristics by increasing the strength of the steel wire. However, high-strength steel wires are highly sensitive to wrinkles, and it is known that fine wrinkles on the surface affect fatigue characteristics, and there is a limit to improving the fatigue limit.
特許文献２に記載のオイルテンパー線は、上記の表面処理が施されているため、表面の平滑性に優れ、表面疵も低減されていると推測されるが、オイルテンパー処理により生成された表面の酸化膜（スケール）も除去されている。オイルテンパー線表面のスケールは、コイリング時に鋼線とばね加工用ツールとの間で潤滑剤として作用するため、特許文献２に記載のオイルテンパー線は、コイリング性が低い。 The oil tempered wire described in Patent Document 2 is presumed to have excellent surface smoothness and reduced surface wrinkles because of the surface treatment described above, but the surface produced by the oil temper treatment The oxide film (scale) is also removed. Since the scale on the surface of the oil tempered wire acts as a lubricant between the steel wire and the spring machining tool during coiling, the oil tempered wire described in Patent Document 2 has low coiling properties.
本発明は、上記事情に鑑みてなされたもので、その目的の一つは、コイリング性ならびに疲労特性に優れたオイルテンパー線とその製造方法を提供することにある。 The present invention has been made in view of the above circumstances, and one of its purposes is to provide an oil tempered wire excellent in coiling properties and fatigue characteristics and a method for producing the same.
また、本発明の別の目的は、上記オイルテンパー線からなるばねを提供することにある。 Another object of the present invention is to provide a spring comprising the oil temper wire.
本発明者らは、オイルテンパー線の表面にスケールを残存させつつ、線表面の疵を低減する手法を見出した。 The present inventors have found a technique for reducing wrinkles on the surface of the oil tempered wire while leaving the scale on the surface.
本発明のオイルテンパー線の製造方法は、鋼線を伸線加工する工程と、伸線加工した鋼線にオイルテンパー処理を施す工程とを具え、伸線加工した後、オイルテンパー処理する前に、鋼線の表面粗さをRzで5.0μm以下とする平滑化処理を施す工程を具えることを特徴とする。 The method for producing an oil tempered wire of the present invention comprises a step of drawing a steel wire and a step of subjecting the drawn steel wire to an oil temper treatment, and after the wire drawing and before the oil temper treatment. The method further comprises a step of performing a smoothing treatment so that the surface roughness of the steel wire is 5.0 μm or less in terms of Rz.
本発明のオイルテンパー線は、鋼線表面にスケールを有し、表面粗さがRzで5.0μm以下であることを特徴とする。 The oil tempered wire of the present invention is characterized by having a scale on the surface of the steel wire and having a surface roughness Rz of 5.0 μm or less.
通常、伸線加工後の鋼線は、伸線加工した際に不可避的に表面にシワ疵などが発生するため、表面粗さがRzで10μm程度である。また、伸線加工条件によっては表面粗さを小さくすることも可能であるが、5μm以下にすることは実用上不可能である。 Usually, a steel wire after wire drawing inevitably generates wrinkles on the surface when it is drawn, so the surface roughness is about 10 μm in Rz. In addition, although the surface roughness can be reduced depending on the wire drawing conditions, it is practically impossible to make the surface roughness 5 μm or less.
本発明の製造方法によれば、伸線加工した後に鋼線表面を平滑化処理し、鋼線の表面粗さをRzで5.0μm以下とするため、伸線加工時に鋼線表面に発生した疵を十分に低減することができる。また、この平滑化処理は、オイルテンパー処理する前に実施するため、表面のスケールが除去されることもない。 According to the manufacturing method of the present invention, the surface of the steel wire is smoothed after the wire drawing process, and the surface roughness of the steel wire is set to 5.0 μm or less by Rz. Can be sufficiently reduced. In addition, since the smoothing process is performed before the oil temper process, the surface scale is not removed.
本発明のオイルテンパー線によれば、鋼線表面にスケールを有しており、コイリング時に鋼線とばね加工用ツール間の潤滑不良によるコイリング疵が付き難く、コイリング性に優れる。また、表面粗さがRzで5.0μm以下であり、表面疵が少なく、表面平滑性に優れていることから、疲労限が向上し、疲労特性に優れている。ここでいう表面粗さとは、ISO468‐1982による十点平均粗さ（Rz）の定義による。 According to the oil tempered wire of the present invention, the steel wire has a scale on the surface thereof, and during coiling, it is difficult for a coiling wrinkle due to poor lubrication between the steel wire and the spring machining tool to occur, and the coiling property is excellent. Further, since the surface roughness is 5.0 μm or less in Rz, there are few surface defects, and the surface smoothness is excellent, the fatigue limit is improved and the fatigue characteristics are excellent. The surface roughness here is based on the definition of 10-point average roughness (Rz) according to ISO468-1982.
本発明において、表面粗さは、オイルテンパー線の状態、即ち表層にスケールが形成された状態で測定して求めた値である。通常、スケールは極めて薄く（1μm以下）、また鋼線表面の凹凸に倣って形成されるため、オイルテンパー処理する前の鋼線の表面粗さとオイルテンパー線の表面粗さとはほぼ同じと考えてよい。 In the present invention, the surface roughness is a value obtained by measurement in an oil tempered wire state, that is, in a state where a scale is formed on the surface layer. Usually, the scale is extremely thin (1 μm or less) and is formed to follow the irregularities on the surface of the steel wire, so the surface roughness of the steel wire before the oil temper treatment and the surface roughness of the oil temper wire are almost the same. Good.
また、表面粗さが小さいほど、表面疵が低減されていることから、疲労限が向上する傾向が認められる。そのため、表面粗さは、Rzで5μm未満、特に4μm以下、更には特に3μm以下とすることが好ましく、下限は、製造上の観点から1μm以上とすることが好ましい。 Moreover, since the surface flaw is reduced as the surface roughness is reduced, a tendency to improve the fatigue limit is recognized. Therefore, the surface roughness Rz is preferably less than 5 μm, particularly 4 μm or less, more preferably 3 μm or less, and the lower limit is preferably 1 μm or more from the viewpoint of production.
本発明において、鋼線表面のスケールは、コイリング性を考慮すれば、厚さを0.2μm以上とすることが好ましい。このような厚さのスケールを形成するには、例えばオイルテンパー処理での焼入れ条件を、加熱温度：850〜1050℃とすればよい。 In the present invention, the scale of the steel wire surface preferably has a thickness of 0.2 μm or more in consideration of coiling properties. In order to form a scale having such a thickness, for example, the quenching condition in the oil temper treatment may be set to a heating temperature of 850 to 1050 ° C.
また、鋼線表面のスケールは、鉄の酸化物、具体的には、酸化第一鉄（FeO）、三酸化二鉄（Fe2O3）及び四酸化三鉄（Fe3O4）で構成されている。この中でも特にFeOは脆く、コイリング時に鋼線表面から剥離してコイリング疵を生じさせる原因となり易いので、スケール中のFeOの比率は、15％以下とすることが好ましく、下限は、製造上の観点から1％以上とすることが好ましい。ここでいうスケール中のFeOの比率とは、鋼線表面のスケールのＸ線回折結果から、FeO、Fe2O3、及びFe3O4の最大ピーク強度をそれぞれ測定し、各ピーク強度の合計に対するFeOのピーク強度の割合（比）である。 The scale of the steel wire surface is composed of iron oxides, specifically ferrous oxide (FeO), ferric trioxide (Fe 2 O 3 ), and triiron tetroxide (Fe 3 O 4 ). Has been. Among these, FeO is particularly brittle and is likely to cause coiling defects due to peeling from the surface of the steel wire during coiling. Therefore, the ratio of FeO in the scale is preferably 15% or less, and the lower limit is a manufacturing viewpoint. To 1% or more. The ratio of FeO in the scale here means the maximum peak intensity of FeO, Fe 2 O 3 , and Fe 3 O 4 from the X-ray diffraction results of the scale on the surface of the steel wire. It is a ratio (ratio) of the peak intensity of FeO to.
本発明の製造方法における平滑化処理としては、鋼線の表面性状を平滑化する方法、具体的には、電解研磨、化学研磨、機械研磨、ショットブラストなどが挙げられ、これらの中から一種以上を選択し、単独で又は組み合わせて用いることができる。機械研磨としては、例えば、砥石を用いた研削加工や、研磨紙或いは遊離砥粒を用いた研磨加工が挙げられる。 Examples of the smoothing treatment in the production method of the present invention include a method of smoothing the surface properties of the steel wire, specifically, electrolytic polishing, chemical polishing, mechanical polishing, shot blasting, and the like. Can be selected and used alone or in combination. Examples of mechanical polishing include grinding using a grindstone and polishing using abrasive paper or loose abrasive grains.
また、鋼線の表面粗さをRzで5.0μm以下とするには、ショットブラストを選択する場合、粒径が50μm以上300μm以下の投射材を使用することが好ましく、研磨紙を用いた研磨加工の場合、粒度#400以上の研磨紙を使用することが好ましい。 Also, in order to reduce the surface roughness of the steel wire to 5.0 μm or less with Rz, when selecting shot blasting, it is preferable to use a projection material having a particle size of 50 μm or more and 300 μm or less, and polishing using abrasive paper In this case, it is preferable to use abrasive paper having a particle size of # 400 or more.
本発明のオイルテンパー線における鋼線は、化学成分として、C、Si、Mn、Cr及びVを含有し、残部がFe及び不可避的不純物からなることが好ましい。以下、上記化学成分の好ましい含有量とその限定理由を説明する。 The steel wire in the oil tempered wire of the present invention preferably contains C, Si, Mn, Cr and V as chemical components, and the balance is composed of Fe and inevitable impurities. Hereinafter, the preferable content of the chemical component and the reason for the limitation will be described.
（C：0.5〜0.8質量％）
Cは、鋼線の強度を決定する重要な元素であり、0.5質量％未満では十分な強度が得られず、0.8質量％超では靭性が低下するため、0.5〜0.8質量％が好ましい。
(C: 0.5-0.8% by mass)
C is an important element that determines the strength of the steel wire, and if it is less than 0.5% by mass, sufficient strength cannot be obtained, and if it exceeds 0.8% by mass, the toughness decreases, so 0.5 to 0.8% by mass is preferable.
（Si：1.0〜2.5質量％）
Siは、鋼の溶製時に脱酸剤として作用する。また、フェライト中に固溶して耐熱性を向上させ、コイリング後の歪取り焼鈍や窒化処理などの熱処理による鋼線の軟化を防止する効果がある。1.0質量％未満では十分な耐熱性向上効果が得られず、2.5質量％超では靭性が低下するため、1.0〜2.5質量％が好ましい。
(Si: 1.0-2.5 mass%)
Si acts as a deoxidizer during the melting of steel. In addition, it has the effect of improving the heat resistance by dissolving in ferrite and preventing the steel wire from being softened by heat treatment such as strain relief annealing or nitriding after coiling. If it is less than 1.0% by mass, a sufficient heat resistance improvement effect cannot be obtained, and if it exceeds 2.5% by mass, the toughness decreases, so 1.0 to 2.5% by mass is preferable.
（Mn：0.2〜1.0質量％）
Mnは、Siと同様に、鋼の溶製時に脱酸剤として作用する。0.2質量％未満では十分な脱酸効果が得られず、1.0質量％超ではパテンチング時にマルテンサイトが生成され易くなり、伸線加工中の断線の原因となるため、0.2〜1.0質量％が好ましい。
(Mn: 0.2-1.0 mass%)
Mn, like Si, acts as a deoxidizer during steel melting. If it is less than 0.2% by mass, a sufficient deoxidation effect cannot be obtained, and if it exceeds 1.0% by mass, martensite is likely to be generated during patenting and causes wire breakage during wire drawing, so 0.2 to 1.0% by mass is preferable.
（Cr：0.5〜2.5質量％）
Crは、鋼の焼入れ性を向上させ、焼入れ焼戻し（オイルテンパー処理）後の軟化抵抗を増大させるため、コイリング後の歪取り焼鈍や窒化処理などの熱処理による鋼線の軟化を防止する効果がある。0.5質量％未満では十分な軟化防止効果が得られず、2.5質量％超ではパテンチング時にマルテンサイトが生成され易くなり、伸線加工中の断線の原因となると共に、オイルテンパー処理後の靭性が低下するため、0.5〜2.5質量％が好ましい。
(Cr: 0.5-2.5% by mass)
Cr improves the hardenability of steel and increases the softening resistance after quenching and tempering (oil tempering), so it has the effect of preventing steel wire softening due to heat treatment such as strain relief annealing and nitriding after coiling . If it is less than 0.5% by mass, a sufficient softening prevention effect cannot be obtained, and if it exceeds 2.5% by mass, martensite is easily generated during patenting, causing wire breakage during wire drawing and reducing toughness after oil tempering. Therefore, 0.5 to 2.5% by mass is preferable.
（V：0.05〜0.5質量％）
Vは、焼戻し時に炭化物を形成し、軟化抵抗を増大させる効果がある。また、コイリング後の窒化処理時にα‐Feの格子間で窒化物を形成し、表面硬度を向上させる効果が期待でき、疲労限の向上に寄与する。0.05質量％未満ではその効果が十分に得られず、0.5質量％超では靭性が低下するため、0.05〜0.5質量％が好ましい。
(V: 0.05-0.5% by mass)
V has the effect of forming carbides during tempering and increasing softening resistance. In addition, nitride is formed between α-Fe lattices during nitriding after coiling, and the effect of improving the surface hardness can be expected, which contributes to the improvement of fatigue limit. If it is less than 0.05% by mass, the effect cannot be sufficiently obtained, and if it exceeds 0.5% by mass, the toughness decreases, so 0.05 to 0.5% by mass is preferable.
更に、本発明のオイルテンパー線における鋼線は、化学成分として、Co、Ni及びMoの群から選択される少なくとも一種を含有してもよい。以下、Co、Ni及びMoの好ましい含有量とその限定理由を説明する。 Furthermore, the steel wire in the oil tempered wire of the present invention may contain at least one selected from the group of Co, Ni and Mo as a chemical component. Hereinafter, preferable contents of Co, Ni, and Mo and reasons for the limitation will be described.
（Co：0.02〜1.0質量％）
Coは、鋼に少量含有させることにより、耐熱性を向上させ、コイリング後の歪取り焼鈍や窒化処理などの熱処理による鋼線の軟化を防止する効果がある。0.02質量％未満ではその効果が十分に得られず、1.0質量％を超えるとその効果がほぼ飽和するので、0.02〜1.0質量％が好ましい。
(Co: 0.02 to 1.0 mass%)
When Co is contained in a small amount in steel, it has an effect of improving heat resistance and preventing softening of the steel wire due to heat treatment such as strain relief annealing or nitriding after coiling. If the amount is less than 0.02% by mass, the effect cannot be sufficiently obtained, and if the amount exceeds 1.0% by mass, the effect is almost saturated, so 0.02 to 1.0% by mass is preferable.
（Ni：0.1〜1.0質量％）
Niは、耐食性及び靭性を向上させる効果がある。0.1質量％未満ではその効果が十分に得られず、1.0質量％を超えると靭性向上効果がほぼ飽和するので、0.1〜1.0質量％が好ましい。
(Ni: 0.1-1.0 mass%)
Ni has the effect of improving corrosion resistance and toughness. If the amount is less than 0.1% by mass, the effect is not sufficiently obtained. If the amount exceeds 1.0% by mass, the effect of improving toughness is almost saturated, so 0.1 to 1.0% by mass is preferable.
（Mo：0.05〜0.5質量％）
Moは、Vと同様に、焼戻し時に炭化物を形成し、軟化抵抗を増大させる効果がある。また、コイリング後の窒化処理時にα‐Feの格子間で窒化物を形成し、表面硬度を向上させる効果が期待でき、疲労限の向上に寄与する。0.05質量％未満ではその効果が十分に得られず、0.5質量％超では靭性が低下するため、0.05〜0.5質量％が好ましい。
(Mo: 0.05-0.5% by mass)
Mo, like V, forms carbides during tempering and has the effect of increasing softening resistance. In addition, nitride is formed between α-Fe lattices during nitriding after coiling, and the effect of improving the surface hardness can be expected, which contributes to the improvement of fatigue limit. If it is less than 0.05% by mass, the effect cannot be sufficiently obtained, and if it exceeds 0.5% by mass, the toughness decreases, so 0.05 to 0.5% by mass is preferable.
本発明のオイルテンパー線を用いることで、耐疲労性に優れたばねを作製することができる。また、コイリング後、必要に応じて、歪取り焼鈍や窒化処理といった熱処理を行なってもよい。 By using the oil tempered wire of the present invention, a spring having excellent fatigue resistance can be produced. Further, after coiling, heat treatment such as strain relief annealing or nitriding treatment may be performed as necessary.
本発明のオイルテンパー線の製造方法は、伸線加工した後、オイルテンパー処理する前に、鋼線表面を平滑化処理するため、オイルテンパー線表面のスケールを残存させつつ、伸線加工時に鋼線表面に発生した疵を十分に除去することができる。 The method for producing an oil tempered wire of the present invention is to smooth the steel wire surface after the drawing process and before the oil tempering process. Wrinkles generated on the wire surface can be sufficiently removed.
本発明のオイルテンパー線は、表面にスケールを有し、且つ、表面粗さがRzで5.0μm以下であるため、コイリング性ならびに疲労特性に優れている。 Since the oil tempered wire of the present invention has a scale on the surface and the surface roughness is 5.0 μm or less in Rz, it is excellent in coiling properties and fatigue characteristics.
表１に示す化学成分の鋼を真空溶解炉で溶製し、鋳造した鋼塊を熱間鍛造、熱間圧延することにより直径6.5mmの線材に加工した。その後、パテンチング、皮剥ぎ、焼鈍、及び伸線加工を行ない、直径1.0mmのワイヤ（鋼線）に加工し、長さ600mmの各種鋼の供試材を作製した。なお、化学成分がＧの鋼は、パテンチング時にマルテンサイトが生成され、伸線加工中に断線が発生したため、化学成分Ｇの鋼線は作製することができなかった。 Steels having chemical components shown in Table 1 were melted in a vacuum melting furnace, and the cast steel ingot was processed into a wire with a diameter of 6.5 mm by hot forging and hot rolling. Thereafter, patenting, skinning, annealing, and wire drawing were performed, and processed into a wire (steel wire) having a diameter of 1.0 mm to prepare various steel specimens having a length of 600 mm. In addition, since the steel with the chemical component G produced martensite at the time of patenting and the wire breakage occurred during the wire drawing, the steel wire with the chemical component G could not be produced.
各種鋼の供試材（但し、化学成分Ｇの鋼は除く）について、オイルテンパー（OT）処理を施し、オイルテンパー線を作製した。また、ショットブラスト（SB）処理を施して、表面粗さを5μm以下に調整したオイルテンパー線も作製した。ここでは、OT処理での焼入れは、900℃の電気炉に供試材を1分間保持することにより行なった。また、SB処理は、投射材として粒径が300μm或いは100μmのスチールショットを使用し、OT処理前或いはOT処理後のいずれかのタイミングで行なった。 Oil tempered wires were prepared by subjecting various steel specimens (excluding steel with chemical component G) to oil temper (OT) treatment. In addition, an oil tempered wire having a surface roughness adjusted to 5 μm or less by performing shot blasting (SB) treatment was also produced. Here, quenching by OT treatment was performed by holding the test material in an electric furnace at 900 ° C. for 1 minute. In addition, the SB treatment was performed using a steel shot having a particle size of 300 μm or 100 μm as the projection material, and at any timing before or after the OT treatment.
作製した各オイルテンパー線について、表面粗さ、スケール中のFeOの比率、疲労特性、及びコイリング性の測定或いは評価を下記の測定方法或いは評価方法に基づいて行なった。その結果を表３に示す。 About each produced oil tempered wire, the measurement or evaluation of surface roughness, the ratio of FeO in a scale, fatigue characteristics, and coiling property was performed based on the following measuring method or evaluation method. The results are shown in Table 3.
なお、表３中において、製造条件の欄が0の場合はSB処理を施していないもの、Iの場合は粒径が300μmの投射材を使用してSB処理を施したもの、IIの場合は粒径が100μmの投射材を使用してSB処理を施したもの、をそれぞれ表している。また、I或いはIIの右に付記された数字は、SB処理のタイミングを表しており、1の場合がOT処理前、2の場合がOT処理後、にSB処理を行なったことをそれぞれ表している。 In Table 3, when the column of manufacturing conditions is 0, the SB treatment is not performed, in the case of I, the SB treatment is performed using a projection material having a particle size of 300 μm, in the case of II Each of these shows a SB treatment using a projection material having a particle size of 100 μm. The numbers appended to the right of I or II indicate the timing of SB processing, where 1 indicates that SB processing was performed before OT processing, and 2 indicates that SB processing was performed after OT processing. Yes.
（表面粗さ）
表面粗さは、ISO486‐1982に準拠して、表面粗さ測定器（株式会社東京精密製サーフコム570A）を用いて、オイルテンパー線表面の十点平均粗さ（Rz）を測定した。
(Surface roughness)
For the surface roughness, the ten-point average roughness (Rz) of the oil tempered wire surface was measured using a surface roughness measuring instrument (Surfcom 570A manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with ISO486-1982.
（スケール中のFeOの比率）
スケール中のFeOの比率は、Ｘ線回折装置を用いてオイルテンパー線表面の組成分析を行ない、線表面のFeO（(111)面）、Fe2O3（(104)面）、及びFe3O4（(311)面）のピーク強度をそれぞれ測定し、各ピーク強度の合計に対するFeOのピーク強度比を算出することにより求めた。ここで、OT処理後にSB処理を行なったオイルテンパー線では、線表面のスケールが完全に除去されていたため、FeOが検出されなかった。
(FeO ratio in the scale)
The ratio of FeO in the scale was determined by analyzing the composition of the oil tempered wire surface using an X-ray diffractometer. FeO ((111) face), Fe 2 O 3 ((104) face), and Fe 3 on the wire surface The peak intensity of O 4 ((311) plane) was measured, and the peak intensity ratio of FeO with respect to the total of each peak intensity was calculated. Here, in the oil tempered wire that was subjected to the SB treatment after the OT treatment, FeO was not detected because the scale of the wire surface was completely removed.
（疲労特性）
疲労特性は、400℃×20分の熱処理を行なった後、中村式回転曲げ疲労試験を実施し、オイルテンパー線の疲労限を測定することにより評価した。ここでは、10７回まで試験を行ない、破断しなかったときの最大振幅応力を疲労限とした。
(Fatigue properties)
Fatigue properties were evaluated by performing a Nakamura rotary bending fatigue test after heat treatment at 400 ° C. for 20 minutes and measuring the fatigue limit of the oil tempered wire. Here, the test was conducted up to 10 7 times, and the maximum amplitude stress when no fracture occurred was defined as the fatigue limit.
（コイリング性）
コイリング性は、オイルテンパー線を表２に示すばね諸元となるようにコイリングした後、ばね表面を観察し、コイリング疵の有無を確認することにより評価した。コイリング疵の有るものを○、コイリング疵の無いものを×とした。
(Coiling)
The coiling property was evaluated by coiling an oil tempered wire so as to have the spring specifications shown in Table 2, and then observing the spring surface and confirming the presence or absence of coiling wrinkles. Those with coiling 疵 were marked with ○, and those without coiling 疵 were marked with ×.
表３から明らかなように、製造条件がI-1或いはII-1のオイルテンパー線は、表面粗さがRzで5μm以下であり、表面粗さがRzで5μm超のオイルテンパー線（製造条件：0）に比べて、疲労限が向上し、疲労特性に優れていることが分かる。また、製造条件がI-1或いはII-1のオイルテンパー線は、表面にスケールを有しており、線表面のスケールが除去されたオイルテンパー線（製造条件：I-2或いはII-2）に比べて、コイリング疵が付き難く、コイリング性に優れていることが分かる。特に、化学成分Ａ〜Ｅのオイルテンパー線は、靭性に優れており、化学成分Ｆ,Ｈのオイルテンパー線に比べて、高い疲労限を示すことが分かる。 As is apparent from Table 3, oil tempered wires with production conditions I-1 or II-1 have an oil tempered wire with a surface roughness Rz of 5 μm or less and a surface roughness Rz of more than 5 μm (production conditions) : Compared to 0), it is understood that the fatigue limit is improved and the fatigue characteristics are excellent. Oil tempered wires with production conditions of I-1 or II-1 have scales on the surface, and oil tempered wires from which the scale of the wire surface has been removed (production conditions: I-2 or II-2) Compared to the above, it can be seen that the coiling wrinkles are not easily attached and the coiling property is excellent. In particular, it can be seen that oil tempered wires of chemical components A to E are excellent in toughness and exhibit a higher fatigue limit than oil tempered wires of chemical components F and H.
通常、SB処理を施した場合、線表面に圧縮残留応力が付与されるために疲労特性が向上することが知られているが、OT処理前にSB処理を施したオイルテンパー線（製造条件：I-1、II-1）は、OT処理後にSB処理を施したオイルテンパー線（製造条件：I-2、II-2）に比べて、疲労限が低い。これは、OT処理前にSB処理を施したオイルテンパー線では、SB処理により線表面に付与された圧縮残留応力が、OT処理によりリセットされることが原因と考えられる。 Normally, when SB treatment is applied, it is known that fatigue characteristics are improved because compressive residual stress is applied to the wire surface. However, oil tempered wire that has undergone SB treatment before OT treatment (manufacturing conditions: I-1 and II-1) have a lower fatigue limit than oil tempered wires (manufacturing conditions: I-2 and II-2) subjected to SB treatment after OT treatment. This is considered to be caused by the fact that the compressive residual stress applied to the wire surface by the SB treatment is reset by the OT treatment in the oil tempered wire that has been subjected to the SB treatment before the OT treatment.
各種鋼の供試材（但し、化学成分Ｇの鋼は除く）について、オイルテンパー（OT）処理と機械研磨（MP）処理を施して、表面粗さを3μm以下に調整したオイルテンパー線を作製した。OT処理は、実施例１と同じ条件で行なった。また、MP処理は、粒度#400の研磨紙で表面を研磨した後、粒度#1200の研磨紙で仕上げ研磨することにより行ない、OT処理前或いはOT処理後のいずれかのタイミングで行なった。 Oil tempered wires with surface roughness adjusted to 3 μm or less are prepared by performing oil temper (OT) treatment and mechanical polishing (MP) treatment on test materials of various steels (excluding steel with chemical component G). did. The OT treatment was performed under the same conditions as in Example 1. The MP treatment was performed by polishing the surface with abrasive paper having a particle size of # 400 and then finish polishing with abrasive paper having a particle size of # 1200, and was performed either before or after the OT treatment.
作製した各オイルテンパー線について、実施例１と同様にして、表面粗さ、スケール中のFeOの比率、疲労特性、及びコイリング性の測定或いは評価を行なった。その結果を表４に示す。ここで、OT処理後にMP処理を行なったオイルテンパー線では、線表面のスケールが完全に除去されていたため、FeOが検出されなかった。 About each produced oil tempered wire, it carried out similarly to Example 1, and measured or evaluated surface roughness, the ratio of FeO in a scale, fatigue characteristics, and coiling property. The results are shown in Table 4. Here, in the oil tempered wire that was subjected to the MP treatment after the OT treatment, FeO was not detected because the scale of the wire surface was completely removed.
なお、表４中において、製造条件の欄のIIIはMP処理を施したものを表しており、IIIの右に付記された数字は、1の場合がOT処理前、2の場合がOT処理後、のタイミングでMP処理を行なったことをそれぞれ表している。 In Table 4, III in the column of manufacturing conditions represents the product subjected to MP treatment, and the numbers appended to the right of III are before OT treatment for 1, and after OT treatment for 2. It represents that the MP process was performed at the timings of.
実施例１の表３と実施例２の表４から明らかなように、表面粗さが3μm以下のオイルテンパー線は、疲労限がより向上しており、表面粗さが小さいほど、疲労限が向上する傾向が認められる。また、製造条件がIII-1のオイルテンパー線は、表面にスケールを有しており、線表面のスケールが除去されたオイルテンパー線（製造条件：III-2）に比べて、コイリング疵が付き難く、コイリング性に優れていることが分かる。 As is clear from Table 3 of Example 1 and Table 4 of Example 2, the oil tempered wire having a surface roughness of 3 μm or less has a further improved fatigue limit. The smaller the surface roughness, the lower the fatigue limit. There is a tendency to improve. In addition, the oil tempered wire with manufacturing conditions of III-1 has a scale on the surface, and compared with the oil tempered wire (manufacturing conditions: III-2) from which the scale on the surface of the wire has been removed It is difficult to see that the coiling property is excellent.
以上の結果から、本発明のオイルテンパー線は、コイリング疵が付き難く、また高い疲労限を有することから、コイリング性ならびに疲労特性に優れていることが分かる。 From the above results, it can be seen that the oil tempered wire of the present invention is less likely to have coiling wrinkles and has a high fatigue limit, and therefore has excellent coiling properties and fatigue characteristics.
なお、本発明は、上述した実施の形態に限定されるものではなく、本発明の要旨を逸脱しない範囲で適宜変更することが可能である。例えば、鋼線の化学成分として、W又はNbを0.05〜0.15質量％含有してもよい。 Note that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the gist of the present invention. For example, you may contain 0.05-0.15 mass% of W or Nb as a chemical component of a steel wire.
本発明のオイルテンパー線及びその製造方法は、耐疲労性が要求されるばね、例えば自動車のエンジン用弁ばねの分野に好適に利用できる。 The oil tempered wire and the method for producing the same of the present invention can be suitably used in the field of springs that require fatigue resistance, such as automotive engine valve springs.
Claims (5)
表面粗さがRzで5.0μm以下であることを特徴とするオイルテンパー線。 An oil tempered wire having a scale on the surface of the steel wire,
An oil tempered wire having a surface roughness Rz of 5.0 μm or less.
伸線加工した後、オイルテンパー処理する前に、鋼線の表面粗さをRzで5.0μm以下とする平滑化処理を施す工程を具えることを特徴とするオイルテンパー線の製造方法。 An oil tempered wire manufacturing method comprising a step of drawing a steel wire and a step of subjecting the drawn steel wire to an oil temper treatment,
A method for producing an oil tempered wire, comprising a step of performing a smoothing treatment to make the surface roughness of a steel wire Rz 5.0 μm or less after the wire drawing and before the oil temper treatment.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2013050195A (en) * | 2011-08-31 | 2013-03-14 | Sumitomo Electric Ind Ltd | Spring steel wire and spring |
| WO2013133070A1 (en) | 2012-03-07 | 2013-09-12 | 株式会社神戸製鋼所 | Steel wire rod with excellent spring workability for high-strength spring, process for manufacturing same, and high-strength spring |
| JP2014169470A (en) * | 2013-03-01 | 2014-09-18 | Kobe Steel Ltd | Spring steel wire excellent in wire drawing property and its manufacturing method |
| JP2017171967A (en) * | 2016-03-22 | 2017-09-28 | 住友電工スチールワイヤー株式会社 | Oil-tempered wire |
| JP2018012868A (en) * | 2016-07-21 | 2018-01-25 | 株式会社神戸製鋼所 | Steel wire for spring |
| JPWO2021255776A1 (en) * | 2020-06-15 | 2021-12-23 | ||
| US11807923B2 (en) | 2020-06-17 | 2023-11-07 | Sumitomo Electric Industries, Ltd. | Spring steel wire |
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| JP2013050195A (en) * | 2011-08-31 | 2013-03-14 | Sumitomo Electric Ind Ltd | Spring steel wire and spring |
| WO2013133070A1 (en) | 2012-03-07 | 2013-09-12 | 株式会社神戸製鋼所 | Steel wire rod with excellent spring workability for high-strength spring, process for manufacturing same, and high-strength spring |
| KR20140120935A (en) | 2012-03-07 | 2014-10-14 | 가부시키가이샤 고베 세이코쇼 | Steel wire rod with excellent spring workability for high-strength spring, process for manufacturing same, and high-strength spring |
| CN104145037A (en) * | 2012-03-07 | 2014-11-12 | 株式会社神户制钢所 | Steel wire rod with excellent spring workability for high-strength spring, process for manufacturing same, and high-strength spring |
| CN104145037B (en) * | 2012-03-07 | 2016-12-14 | 株式会社神户制钢所 | The steel wire for high-strength spring material of spring excellent in workability and manufacture method thereof and high-strength spring |
| JP2014169470A (en) * | 2013-03-01 | 2014-09-18 | Kobe Steel Ltd | Spring steel wire excellent in wire drawing property and its manufacturing method |
| JP2017171967A (en) * | 2016-03-22 | 2017-09-28 | 住友電工スチールワイヤー株式会社 | Oil-tempered wire |
| JP2018012868A (en) * | 2016-07-21 | 2018-01-25 | 株式会社神戸製鋼所 | Steel wire for spring |
| JPWO2021255776A1 (en) * | 2020-06-15 | 2021-12-23 | ||
| WO2021255776A1 (en) * | 2020-06-15 | 2021-12-23 | 住友電気工業株式会社 | Steel wire for spring |
| JP7287403B2 (en) | 2020-06-15 | 2023-06-06 | 住友電気工業株式会社 | steel wire for spring |
| US11892048B2 (en) | 2020-06-15 | 2024-02-06 | Sumitomo Electric Industries, Ltd. | Spring steel wire |
| US11807923B2 (en) | 2020-06-17 | 2023-11-07 | Sumitomo Electric Industries, Ltd. | Spring steel wire |
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