JP5155634B2 - Stainless steel wire for hydrogen resistant spring and hydrogen resistant spring product using the same - Google Patents

Stainless steel wire for hydrogen resistant spring and hydrogen resistant spring product using the same Download PDF

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JP5155634B2
JP5155634B2 JP2007252225A JP2007252225A JP5155634B2 JP 5155634 B2 JP5155634 B2 JP 5155634B2 JP 2007252225 A JP2007252225 A JP 2007252225A JP 2007252225 A JP2007252225 A JP 2007252225A JP 5155634 B2 JP5155634 B2 JP 5155634B2
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JP2009084597A (en
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好則 谷本
孝之 秋月
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Nippon Seisen Co Ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30Hydrogen technology
    • Y02E60/50Fuel cells
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

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Description

本発明は、高圧の水素ガス環境下で使用されるばね製品用材として使用され、耐水素脆性と良好なばね特性とを兼ね具えた耐水素性に優れたばね製品を製作しうる耐水素性ばね用ステンレス鋼線、及びそれを用いた耐水素性ばね製品に関する。   The present invention is a stainless steel for hydrogen resistant springs that can be used as a spring product material used in a high-pressure hydrogen gas environment, and that can produce a spring product with excellent hydrogen resistance that combines hydrogen embrittlement resistance and good spring characteristics. The present invention relates to a wire and a hydrogen-resistant spring product using the wire.

家庭用あるいは自動車用などの燃料電池は、例えば水の電気分解で発生する酸素と水素を活用する方式がその1つとして知られているが、エネルギー効率を図る観点から水素ガスの使用環境は高温高圧化される傾向にある。   For example, a method of utilizing oxygen and hydrogen generated by electrolysis of water is known as one of the fuel cells for home use or automobiles. However, the use environment of hydrogen gas is high from the viewpoint of energy efficiency. There is a tendency to increase pressure.

ところで、このような燃料電池に用いる、特に金属線材を用いるばね製品では機械的特性、耐食性、耐熱性などの基本特性とともに、水素環境下での水素脆性、水素に起因する遅れ破壊を生じにくい耐水素性に優れることが必須であり、ステンレス鋼では例えばSUS310、SUS316L等の高Ni量のオーステナイト系ステンレス鋼、又はチタン材料などが用いられている。   By the way, spring products used in such fuel cells, especially metal wires, have basic characteristics such as mechanical characteristics, corrosion resistance, and heat resistance, as well as water resistance that is unlikely to cause hydrogen embrittlement in hydrogen environments and delayed fracture due to hydrogen. It is indispensable to have excellent features. For stainless steel, for example, a high Ni amount austenitic stainless steel such as SUS310 or SUS316L, or a titanium material is used.

例えばこのような、オーステナイト系ステンレス鋼として、水素侵入による耐遅れ破壊性を向上させ、高強度と高靭性とを具えるステンレス鋼板として、加工誘起マルテンサイト相と20体積%以上の残留オーステナイト相からなり、オーステナイト粒のアスペクト比を3以上の伸長組織にすることによりHv450以上の高強度化を図る提案(例えば特許文献1参照)、耐水素脆性が要求されるばね用ステンレス鋼線に関し、C:0.01〜0.25%,N:0.01〜0.25%,Mn:0.5〜4.0%,Cr:16〜20%,Ni:8.0〜14.0%を含有するとともに、C+N:0.15〜0.35%とし、引張強さ1300〜2000N/mmで、マルテンサイト相が10体積%以下とする提案(特許文献2参照)がある。 For example, as an austenitic stainless steel, the delayed fracture resistance due to hydrogen intrusion is improved, and a stainless steel plate having high strength and toughness is obtained from a work-induced martensite phase and a residual austenite phase of 20% by volume or more. Thus, a proposal for increasing the strength of Hv450 or more by making the austenite grains have an aspect ratio of 3 or more (see, for example, Patent Document 1), and a stainless steel wire for springs requiring hydrogen embrittlement resistance, C: Contains 0.01 to 0.25%, N: 0.01 to 0.25%, Mn: 0.5 to 4.0%, Cr: 16 to 20%, Ni: 8.0 to 14.0% In addition, C + N: 0.15 to 0.35%, a tensile strength of 1300 to 2000 N / mm 2 and a martensite phase of 10% by volume or less (see Patent Document 2) are proposed.

特開2003−113449号公報JP 2003-113449 A 特開2003−226940号公報JP 2003-226940 A

しかしながら、特許文献1の発明は、ステンレス鋼を素材にして、耐遅れ破壊性を向上させ、しかも表面硬度をビッカース硬度450以上にした高強度・高靭性ステンレス鋼板とその高強度・高靭性ステンレス鋼板を製造する方法であって、冷延後、加工誘起マルテンサイトを80体積%以下として破壊に寄与する拡散水素絶対量を小とし、かつ残留オーステナイトを20体積%以上として疲労特性の向上を意図するが、技術の分野が無段変速機ベルト用の鋼板であることに関連してばね特性としての改善は達成されたものとは言えない。   However, the invention of Patent Document 1 is a high-strength, high-toughness stainless steel plate that uses stainless steel as a raw material to improve delayed fracture resistance and has a surface hardness of Vickers hardness of 450 or higher, and its high-strength, high-toughness stainless steel plate. Is intended to improve fatigue properties after cold rolling by setting the work-induced martensite to 80 volume% or less to reduce the absolute amount of diffused hydrogen contributing to fracture and to setting the residual austenite to 20 volume% or more. However, it cannot be said that the improvement in spring characteristics has been achieved in connection with the technical field of steel plates for continuously variable transmission belts.

又引用文献2の発明は、水素雰囲気において耐疲労性、耐水素脆性に優れ、かつ低コストなばね用ステンレス鋼線、ばね、乃至その製造方法を提供するという本発明と同様な課題を有するが、このものは、Fe基であるオーステナイト系ステンレスに対し、特に、C、Nの含有量、及び加工誘起マルテンサイト相の含有量を規定することで課題を達成するものとしているが、成分的にオーステナイト相の安定化が十分でなく、耐水素脆性をより高める為には更なる改良が望まれている。   The invention of Cited Document 2 has the same problem as the present invention in that it provides a stainless steel wire for springs, a spring, and a manufacturing method thereof that are excellent in fatigue resistance and hydrogen embrittlement resistance in a hydrogen atmosphere and at low cost. , This is to achieve the problem by defining the content of C, N, and the content of work-induced martensite phase, especially for the austenitic stainless steel that is Fe-based. The austenite phase is not sufficiently stabilized, and further improvement is desired in order to further improve hydrogen embrittlement resistance.

本発明は製造が容易であって、高圧水素ガスの環境下における水素脆性を抑制でき安定して使用でき、かつばね製品に使用可能な耐水素性に優れたばね用ステンレス鋼線、及びそれを用いた耐水素性ばね製品の提供を目的とする。   The present invention is easy to manufacture, suppresses hydrogen embrittlement in a high-pressure hydrogen gas environment, can be used stably, and has excellent hydrogen resistance that can be used for spring products, and a spring stainless steel wire using the same The purpose is to provide hydrogen-resistant spring products.

請求項1に係る発明は、質量%で、C:0.08%以下、Si:1.0%以下、Mn:4.0〜15.0%、Ni:5.0〜15.0%、Cr:18.0〜25.0%、Mo:0.5〜3.0%、N:0.3〜0.8%を含み、かつ残部Feと不可避不純物とからなるとともに、次式(1)のA値を30.0〜40.0%に調整したオーステナイト系ステンレス鋼で構成され、かつ
引張強さは1000〜2000MPa、該引張強さと0.2%耐力との比で示される耐力比(〔0.2%耐力/引張強さ〕×100%)を60〜90%とする冷間加工がなされ、その格子結晶構造が面心立方晶を有することを特徴とする耐水素性ばね用ステンレス鋼線である。
A=0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6(C+N)+Ni…(1)
The invention according to claim 1 is mass%, C: 0.08% or less, Si: 1.0% or less, Mn: 4.0-15.0%, Ni: 5.0-15.0%, Cr: 18.0 to 25.0%, Mo: 0.5 to 3.0%, N: 0.3 to 0.8%, and the balance is composed of Fe and inevitable impurities. It is composed of austenitic stainless steel whose A value in 1) is adjusted to 30.0 to 40.0%, and the tensile strength is 1000 to 2000 MPa, the yield strength represented by the ratio of the tensile strength and 0.2% yield strength. For hydrogen resistant springs, characterized in that the ratio ([0.2% yield strength / tensile strength] × 100%) is cold worked to 60 to 90% and the lattice crystal structure has face centered cubic crystals. Stainless steel wire.
A = 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si + 12.6 (C + N) + Ni (1)

請求項2に係る発明は、前記オーステナイト系ステンレス鋼が、質量%で、C:0.005〜0.05%、Si:0.05〜0.40%、Mn:4.5〜8.0%、Ni:8.0〜11.0%、Cr:20.0〜25.0%、Mo:0.8〜3.0%、N:0.4〜0.65%を含み、かつ残部Feと不可避不純物とからなることを特徴としている。
According to a second aspect of the present invention, the austenitic stainless steel is, by mass, C: 0.005 to 0.05%, Si: 0.05 to 0.40%, Mn: 4.5 to 8.0. %, Ni: 8.0 to 11.0%, Cr: 20.0 to 25.0%, Mo: 0.8 to 3.0%, N: 0.4 to 0.65%, and the balance There has been characterized to consist of Fe and unavoidable impurities.

請求項3に係る発明は、質量%で、C:0.08%以下、Si:1.0%以下、Mn:4.0〜15.0%、Ni:5.0〜15.0%、Cr:18.0〜25.0%、Mo:0.5〜3.0%、N:0.3〜0.8%、Ti:0.001〜0.1%、Mg:0.001〜0.02%を含み、かつ残部がFeと不可避不純物とからなるとともに、次式(1)のA値を30.0〜40.0%に調整したオーステナイト系ステンレス鋼で構成され、かつ
引張強さは1000〜2000MPa、該引張強さと0.2%耐力との比で示される耐力比(〔0.2%耐力/引張強さ〕×100%)を60〜90%とする冷間加工がなされ、その加工後の格子結晶構造が面心立方晶(fcc)を有することを特徴とする耐水素性ばね用ステンレス鋼線である。
A=0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6(C+N)+Ni…(1)
また、請求項4に係る発明は、質量%で、C:0.08%以下、Si:1.0%以下、Mn:4.0〜15.0%、Ni:5.0〜15.0%、Cr:18.0〜25.0%、Mo:0.5〜3.0%、N:0.3〜0.8%、Al:0.005〜0.05%を含み、かつ残部がFeと不可避不純物とからなるとともに、次式(1)のA値を30.0〜40.0%に調整したオーステナイト系ステンレス鋼で構成され、かつ
引張強さは1000〜2000MPa、該引張強さと0.2%耐力との比で示される耐力比(〔0.2%耐力/引張強さ〕×100%)を60〜90%とする冷間加工がなされ、その加工後の格子結晶構造が面心立方晶(fcc)を有することを特徴とする耐水素性ばね用ステンレス鋼線である。
A=0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6(C+N)+Ni…(1)
また、請求項5に係る発明は、質量%で、C:0.08%以下、Si:1.0%以下、Mn:4.0〜15.0%、Ni:5.0〜15.0%、Cr:18.0〜25.0%、Mo:0.5〜3.0%、N:0.3〜0.8%、V:0.005〜0.5%を含み、かつ残部がFeと不可避不純物とからなるとともに、次式(1)のA値を30.0〜40.0%に調整したオーステナイト系ステンレス鋼で構成され、かつ
引張強さは1000〜2000MPa、該引張強さと0.2%耐力との比で示される耐力比(〔0.2%耐力/引張強さ〕×100%)を60〜90%とする冷間加工がなされ、その加工後の格子結晶構造が面心立方晶(fcc)を有することを特徴とする耐水素性ばね用ステンレス鋼線である。
A=0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6(C+N)+Ni…(1)


The invention according to claim 3 is mass%, C: 0.08% or less, Si: 1.0% or less, Mn: 4.0-15.0%, Ni: 5.0-15.0%, Cr: 18.0-25.0%, Mo: 0.5-3.0%, N: 0.3-0.8%, Ti: 0.001-0.1%, Mg: 0.001- 0.02% is included, the balance is made of Fe and inevitable impurities, and the A value of the following formula (1) is adjusted to 30.0 to 40.0%, and is composed of austenitic stainless steel, and
The tensile strength is 1000 to 2000 MPa, and the yield strength ratio ([0.2% yield strength / tensile strength] × 100%) indicated by the ratio between the tensile strength and 0.2% yield strength is 60 to 90% cold. A stainless steel wire for a hydrogen resistant spring characterized in that the lattice crystal structure after being processed has face centered cubic (fcc).
A = 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si + 12.6 (C + N) + Ni (1)
The invention according to claim 4 is mass%, C: 0.08% or less, Si: 1.0% or less, Mn: 4.0-15.0%, Ni: 5.0-15.0 %, Cr: 18.0 to 25.0%, Mo: 0.5 to 3.0%, N: 0.3 to 0.8%, Al: 0.005 to 0.05%, and the balance Is composed of Fe and inevitable impurities, and is composed of austenitic stainless steel in which the A value of the following formula (1) is adjusted to 30.0 to 40.0%, and
The tensile strength is 1000 to 2000 MPa, and the yield strength ratio ([0.2% yield strength / tensile strength] × 100%) indicated by the ratio between the tensile strength and 0.2% yield strength is 60 to 90% cold. A stainless steel wire for a hydrogen resistant spring characterized in that the lattice crystal structure after being processed has face centered cubic (fcc).
A = 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si + 12.6 (C + N) + Ni (1)
Moreover, the invention which concerns on Claim 5 is the mass%, C: 0.08% or less, Si: 1.0% or less, Mn: 4.0-15.0%, Ni: 5.0-15.0 %, Cr: 18.0 to 25.0%, Mo: 0.5 to 3.0%, N: 0.3 to 0.8%, V: 0.005 to 0.5%, and the balance Is composed of Fe and inevitable impurities, and is composed of austenitic stainless steel in which the A value of the following formula (1) is adjusted to 30.0 to 40.0%, and
The tensile strength is 1000 to 2000 MPa, and the yield strength ratio ([0.2% yield strength / tensile strength] × 100%) indicated by the ratio between the tensile strength and 0.2% yield strength is 60 to 90% cold. A stainless steel wire for a hydrogen resistant spring characterized in that the lattice crystal structure after being processed has face centered cubic (fcc).
A = 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si + 12.6 (C + N) + Ni (1)


又請求項に係る発明は、前記引張強さが1300〜1600MPaで、耐力比が65〜75%であることを特徴とし、さらに請求項に係る発明は、前記オーステナイト系ステンレス鋼が、その表面上の不動態被膜が厚さ15〜50nmに調整されたものであることを特徴とし、さらに請求項8に係る発明は、表面にNi又はCuの金属被覆を具えることを特徴とする。

The invention according to claim 6 is characterized in that the tensile strength is 1300 to 1600 MPa and the proof stress ratio is 65 to 75%, and the invention according to claim 7 is characterized in that the austenitic stainless steel has The passive film on the surface is adjusted to a thickness of 15 to 50 nm, and the invention according to claim 8 further includes a metal coating of Ni or Cu on the surface. .

請求項に係る発明は耐水素性ばね製品に関し、請求項1〜8のいずれかに記載の耐水素性ばね用ステンレス鋼線を用いてばね形状に成形され、かつその格子結晶構造は面心立方晶を有するとともに、設定負荷応力500MPa及び応力振幅±180MPaの条件で繰返し試験した時のばね疲労特性が、1.0×10回以上であることを特徴とする耐水素性ばね製品である。
The invention according to claim 9 relates to a hydrogen-resistant spring product, and is formed into a spring shape using the stainless steel wire for hydrogen-resistant spring according to any one of claims 1 to 8 , and the lattice crystal structure thereof is a face-centered cubic crystal. In addition, the spring fatigue characteristics when repeatedly tested under conditions of a set load stress of 500 MPa and a stress amplitude of ± 180 MPa are 1.0 × 10 6 times or more.

さらに請求項10に係る発明は、前記耐水素性ばね製品が、35〜100MPaの高圧水素環境下で使用されるものであることを特徴とする。
The invention according to claim 10 is characterized in that the hydrogen-resistant spring product is used in a high-pressure hydrogen environment of 35 to 100 MPa.

本願請求項1に係る発明は、前記成分組成とともに各組成のバランスを示すA値を30.0〜40.0%に調整することで、水素に対する材料組織の安定化を図るとともに、その引張強さが1000〜2000MPa、かつ前記耐力比を60〜90%に冷間加工したものでありながらも、その格子結晶構造が面心立方晶に調整されたものとしており、こうした要件の設定によって、ばね用としての所定強度を備えつつ水素に対する影響を減じることが可能となる。なお、前記耐力比は、(〔0.2%耐力値/引張強さ〕×100%)の算式で求められる。   The invention according to claim 1 of the present application aims to stabilize the material structure against hydrogen by adjusting the A value indicating the balance of each composition together with the component composition to 30.0 to 40.0%, and to obtain the tensile strength thereof. The lattice crystal structure is adjusted to a face-centered cubic crystal even though the strength is 1000 to 2000 MPa and the yield ratio is cold worked to 60 to 90%. It is possible to reduce the influence on hydrogen while having a predetermined strength for use. The yield strength ratio is determined by the formula ([0.2% yield strength value / tensile strength] × 100%).

また本発明では、耐水素性のばね用ステンレス鋼線として、前記引張強さを通常のばね材料と比較して比較的低く抑えたものとし、かつ前記耐力比との調整によってばね製品での疲労特性、耐へたり特性の影響を減じるものとしている。この場合、実質的なばね特性は、例えば設計時でのばね形状、寸法比(コイル径D/線径d)の選択等、仕様調整によって対応可能である為、使用上での疲労等の問題は解消できる。なお前記“へたり性”については、例えば成形ばねに所定応力を負荷した後のばね形状(例えば、ばね自由長)の変化量を、元の自由長で除して百分率換算したもので示される。   Further, in the present invention, as a hydrogen-resistant spring stainless steel wire, the tensile strength is relatively low compared to a normal spring material, and the fatigue characteristics of the spring product are adjusted by adjusting the strength ratio. The effect of sag resistance is to be reduced. In this case, the substantial spring characteristics can be dealt with by adjusting the specifications such as selection of the spring shape and dimensional ratio (coil diameter D / wire diameter d) at the time of design. Can be resolved. The “sagging” is indicated by, for example, a percentage conversion of a change amount of a spring shape (for example, a spring free length) after a predetermined stress is applied to a molded spring, divided by the original free length. .

また請求項2乃至5に係わる発明は、オーステナイト系ステンレス鋼の材料組成をより適正に調整しており、ばね特性と耐水素性を更に高めることができる。
In the inventions according to claims 2 to 5 , the material composition of the austenitic stainless steel is adjusted more appropriately, and the spring characteristics and hydrogen resistance can be further improved.

請求項に係わる発明は、前記引張強さが1300〜1600MPaで、かつ前記耐力比が65〜75%でばね用としての必要特性を保有し、また前記成分組成との相乗効果で耐水素性に優れたばね製品を提供できる。
In the invention according to claim 6 , the tensile strength is 1300 to 1600 MPa, the yield strength ratio is 65 to 75%, the necessary characteristics for a spring are retained, and the synergistic effect with the component composition makes the hydrogen resistance better. We can provide excellent spring products.

請求項に係る発明は、その表面上の不動態被膜の厚さが15〜50nmの微薄厚さを有する耐水素性ばね用ステンレス鋼線としている。このような微薄厚さの不動態被膜は非常にタイトかつ緻密であり、それ故耐水素性ばね用ステンレス鋼線及びそれを用いた耐水素性ばね製品の水素雰囲気中での使用における水素の鋼線内部への侵入を減少させることができる。
The invention according to claim 7 is a stainless steel wire for a hydrogen-resistant spring having a thickness of a passive film on the surface of 15 to 50 nm. Such a thin-film passive film is very tight and dense, and therefore the inside of a hydrogen steel wire for use in a hydrogen atmosphere of a stainless steel wire for hydrogen resistant springs and a hydrogen resistant spring product using the same. Intrusion into can be reduced.

このように請求項の発明によれば、ステンレス鋼の生地マトリックスに比して表面層での外部水素の侵入を前記不動態被膜で抑制するバリア機能と、前記所定成分組成を有し、かつA値を30.0〜40.0%に高めたことの二段階の制御手段によって、通常の固溶状態での許容量(例えば3ppm程度)以上の水素の残留を抑え、水素脆化の問題を抑制することができる。
Thus, according to the invention of claim 7 , it has a barrier function that suppresses intrusion of external hydrogen in the surface layer with the passive film as compared with the dough matrix of stainless steel, and the predetermined component composition, and The two-step control means that the A value is increased to 30.0 to 40.0% suppresses the remaining hydrogen exceeding the allowable amount (for example, about 3 ppm) in a normal solid solution state, and the problem of hydrogen embrittlement Can be suppressed.

更に請求項に係る発明は、前記いずれかのステンレス鋼線によって所定のばね形状に成形され、かつその格子結晶構造が面心立方晶を有するとともに、所定条件でばね疲労試験した時のばね特性が1.0×10回以上を有する、耐水素性とばね特性の両面で優れたばね製品が提供できる。
Further, the invention according to claim 9 is a spring characteristic when the spring crystal is formed into a predetermined spring shape by any of the stainless steel wires and the lattice crystal structure has a face-centered cubic crystal, and a spring fatigue test is performed under a predetermined condition. There has more than 1.0 × 10 6 times, it can provide spring product excellent in both water resistance feature and spring characteristics.

請求項10に係わる発明は、35〜100MPaの高圧水素環境下で使用されるときに請求項記載の前記ばね特性を有するばね製品であって、これによって例えば水素ステーションでの水素供給用カプラに組み込まれる高圧ガス用のばね製品などとして、その用途範囲を広めることができる。
The invention according to claim 10 is the spring product having the spring characteristics according to claim 9 when used in a high-pressure hydrogen environment of 35 to 100 MPa, thereby providing, for example, a coupler for supplying hydrogen at a hydrogen station. As a spring product for high-pressure gas to be incorporated, the application range can be widened.

本発明は、(1)式のA値を30.0〜40.0%に調整した成分組成を有するオーステナイト系ステンレス鋼からなり、引張強さを1000〜2000MPaとし、60〜90%の耐力比を備えて冷間加工されたものでありながらも、その格子結晶構造は面心立方晶を備える耐水素性とばね性に優れたばね用ステンレス鋼線であって、次の成分組成を有するものとしている。
A=0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6(C+N)+Ni…(1)
This invention consists of austenitic stainless steel which has the component composition which adjusted A value of (1) Formula to 30.0-40.0%, tensile strength shall be 1000-2000 MPa, and a proof stress ratio of 60-90% The lattice crystal structure is a stainless steel wire for springs that has face-centered cubic crystals and is excellent in hydrogen resistance and spring properties, and has the following component composition. .
A = 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si + 12.6 (C + N) + Ni (1)

具体的には、質量%で、C:0.08%以下、Si:1.0%以下、Mn:4.0〜15.0%、Ni:5.0〜15.0%、Cr:18.0〜25.0%、Mo:0.5〜3.0%、 N:0.3〜0.8%を含み、かつ残部Feと不可避不純物とで構成するとともに、前記A値を30.0〜40.0%設定している。
Specifically, by mass%, C: 0.08% or less, Si: 1.0% or less, Mn: 4.0-15.0%, Ni: 5.0-15.0%, Cr: 18 0.0-25.0%, Mo: 0.5-3.0%, N: 0.3-0.8%, and the balance is composed of Fe and inevitable impurities, and the A value is 30. 0.0 to 40.0% is set.

本発明において「耐水素性」とは、材料内部に水素が侵入したときの水素による脆化、脆性破壊(遅れ破壊)現象の発生を減少乃至抑制し、あるいは外界からの水素侵入を抑止し得るバリア的な働きを備え、侵入水素による脆化現象の誘発を抑えた機能を総称する意味で用いる。   In the present invention, the term “hydrogen resistance” refers to a barrier that can reduce or suppress the occurrence of embrittlement and brittle fracture (delayed fracture) phenomenon when hydrogen enters the material, or can suppress hydrogen intrusion from the outside. It is used to generically refer to functions that have a typical function and suppress the induction of embrittlement due to invading hydrogen.

水素脆化の発生機構については、従来から水素ガス圧説、転位説、水素吸着説、格子脆化説等、種々の学説が知られており、また例えば「水素と金属」(2002年4月、内田老鶴圃発行:P.210)では、その金属中に存在していた水素、気相反応等によって外界から侵入した水素が結晶中の拡散や運動転位によって移動しながら粒界、析出物、非金属介在物などとマトリックスとの界面などの強いトラップサイトに残留し、その近傍で金属原子間の結合が弱められ、結果的に微小ボイドやクラックが発生して最終的に破壊に至るものとされている。   Regarding the mechanism of hydrogen embrittlement, various theories such as hydrogen gas theory, dislocation theory, hydrogen adsorption theory, and lattice embrittlement theory have been known. For example, “hydrogen and metal” (April 2002) In Uchida Otsukaku, P.210), the hydrogen present in the metal, the hydrogen that invaded from the outside due to the gas phase reaction, etc. moved by the diffusion and motion dislocation in the crystal, and the grain boundaries and precipitates. Residues at strong trap sites such as the interface between non-metallic inclusions and the matrix, and the bond between metal atoms is weakened in the vicinity, resulting in the formation of microvoids and cracks that eventually lead to destruction It is said that.

このような水素脆性を抑制するために、本発明ではオーステナイト相を安定化して歪誘起マルテンサイト変態を抑制させるとともに、耐水素性に優れたばね用ステンレス鋼線として、その成分組成を前記範囲に設定している。   In order to suppress such hydrogen embrittlement, in the present invention, the austenite phase is stabilized to suppress strain-induced martensitic transformation, and the component composition is set in the above range as a stainless steel wire for springs having excellent hydrogen resistance. ing.

なお好ましくは、前記成分組成が、C:0.005〜0.05%、Si:0.05〜0.40%、Mn:4.5〜8.0%、Ni:8.0〜11.0%、Cr:20.0〜25.0%、Mo:0.8〜3.0%、N:0.4〜0.65%を含むものとする。更に任意元素として、Ti:0.001〜0.1%及びMg:0.001〜0.02%の組み合わせ、Al:0.005〜0.05%のみ、又は、V:0.005〜0.5%のみを含有することもできる。
Preferably, the component composition is C: 0.005-0.05%, Si: 0.05-0.40%, Mn: 4.5-8.0%, Ni: 8.0-11. It shall contain 0%, Cr: 20.0-25.0%, Mo: 0.8-3.0%, N: 0.4-0.65% . Further, as an optional element, a combination of Ti: 0.001 to 0.1% and Mg : 0.001 to 0.02%, Al: only 0.005 to 0.05%, or V: 0.005 to 0 It can also contain only 5% .

ここで、本発明において前記耐水素性ばね用ステンレス鋼線における各成分組成の分量の限定理由は次による。   Here, the reason for limiting the amount of each component composition in the stainless steel wire for hydrogen resistant spring in the present invention is as follows.

C: Cは結晶格子中に侵入する侵入型元素で強力なオーステナイトを形成して前記A値を高める。又加工ひずみを伴う加工硬化によってマトリックス中の生地強度を高めて高強度化をもたらす。しかし、0.08%を超えるとCrとの炭化物を形成し、この炭化物が結晶粒界に存在することで、水素脆性の原因になるとともに、ワイヤー自体の耐食性を低下させる。この為、その上限を0.08%とし、より好ましくは0.06%以下、更に好ましくは0.005〜0.05%とする。   C: C is an interstitial element that penetrates into the crystal lattice and forms strong austenite to increase the A value. In addition, the strength of the dough in the matrix is increased by work hardening accompanied by processing strain, resulting in higher strength. However, if it exceeds 0.08%, a carbide with Cr is formed, and the presence of this carbide at the crystal grain boundary causes hydrogen embrittlement and lowers the corrosion resistance of the wire itself. For this reason, the upper limit is made 0.08%, more preferably 0.06% or less, still more preferably 0.005 to 0.05%.

Si: Siは溶解精錬時の脱酸剤として用いられ、固溶によって機械的特性の向上を図ることができる。しかし1.0%を超える以上の添加は加工性を低下させ、高強度、かつ細径化を意図する場合のばね用とするには好ましくない。したがってその上限を1.0%とし、より好ましくは0.05〜0.40%とする。   Si: Si is used as a deoxidizing agent at the time of dissolution and refining, and mechanical properties can be improved by solid solution. However, addition exceeding 1.0% is not preferable for use in springs when the workability is lowered and high strength and diameter reduction are intended. Therefore, the upper limit is made 1.0%, and more preferably 0.05 to 0.40%.

Mn: MnもSiと同様に溶解精錬時の脱酸剤として使用され、またオーステナイト相を安定化する安定化元素であり、その添加によって高価なNiの代替として用いうる。
またその添加はNの固溶限を高める効果もあることから少なくとも4.0%以上の添加とする。しかし多量の添加は高温での耐酸化性、熱間加工性に影響を及ぼすため上限を15.0%とする。より好ましくは4.5〜8.0%とする。
Mn: Similar to Si, Mn is also used as a deoxidizer during melting and refining, and is a stabilizing element that stabilizes the austenite phase, and can be used as an alternative to expensive Ni by its addition.
Moreover, since the addition has an effect of increasing the solid solubility limit of N, the addition is at least 4.0% or more. However, the addition of a large amount affects the oxidation resistance at high temperatures and the hot workability, so the upper limit is made 15.0%. More preferably, the content is 4.5 to 8.0%.

Ni: Niはオーステナイト系ステンレス鋼の基本的元素で、その添加によってオーステナイト相の安定化を図り、変形抵抗を低下させて冷間加工性を向上したり、耐食性を高めるなどの効果があり、本発明の耐水素ばね用材料として有効である。この為、少なくとも5.0%以上を含有するが、多量の添加はコスト上昇を招くことから上限を15.0%とする。より好ましくは8.0〜11.0%とする。   Ni: Ni is a basic element of austenitic stainless steel, and its addition has the effect of stabilizing the austenite phase, reducing deformation resistance, improving cold workability, and improving corrosion resistance. It is effective as a material for a hydrogen resistant spring of the invention. For this reason, it contains at least 5.0% or more, but since the addition of a large amount causes an increase in cost, the upper limit is made 15.0%. More preferably, the content is 8.0 to 11.0%.

Cr: Crも前記Niと同様にオーステナイト系ステンレス鋼の基本的組成で、表面上に酸化被膜(不動態被膜)を形成して耐食性、耐熱特性、耐酸化特性を向上するとともに、適量の添加はワイヤーの靭性を高めてばね加工性を高める効果もあり有効である。しかしその量が25.0%を超えるものでは靭性が損なわれ、コイリング加工性を低下させることから、本発明では18.0〜25.0%の含有、より好ましくは20.0〜25.0%とする。   Cr: Cr is also a basic composition of austenitic stainless steel like Ni, and an oxide film (passive film) is formed on the surface to improve corrosion resistance, heat resistance characteristics and oxidation resistance characteristics. It also has the effect of increasing the toughness of the wire and improving the spring workability, which is effective. However, if the amount exceeds 25.0%, the toughness is impaired and the coiling workability is lowered. Therefore, in the present invention, the content is 18.0 to 25.0%, more preferably 20.0 to 25.0. %.

Mo: Moはオーステナイト相中に固溶することで同時にNの固溶量を高め、疲労特性を向上し耐食性を高めるなどの効果がある。しかし熱間加工性を低下させて製造歩留まり/コスト面に影響することから、本発明では0.5〜3.0%の含有とし、より好ましくは0.8〜3.0%とする。   Mo: Mo dissolves in the austenite phase, thereby increasing the solid solution amount of N, improving fatigue characteristics and improving corrosion resistance. However, since the hot workability is deteriorated to affect the production yield / cost, the content of the present invention is 0.5 to 3.0%, and more preferably 0.8 to 3.0%.

N: Nは侵入型元素で、その添加によって結晶粒を微細化し、強度の上昇、オーステナイト相の安定化、耐食性向上等の効果をもたらす。しかしその含有には高度の技術を必要とし、材料費を高めるとともに例えば溶解、鋳造時にブローホールを形成するなどの問題もある為、本発明では0.3〜0.8%、より好ましくは0.4〜0.65%とする。   N: N is an interstitial element, and its addition refines the crystal grains and brings about effects such as an increase in strength, stabilization of the austenite phase, and improvement in corrosion resistance. However, its inclusion requires a high level of technology, increases the material cost, and has problems such as forming blowholes during melting and casting. Therefore, in the present invention, 0.3 to 0.8%, more preferably 0 .4 to 0.65%.

また、必要に応じて任意に添加される前記任意元素については、粒界腐食を生じさせるCとの親和力が大きく安定にでき、また耐水素脆性に対しても有効に作用する。
Further, the optional element that is optionally added as necessary can have a large and stable affinity with C that causes intergranular corrosion, and also effectively acts against hydrogen embrittlement resistance.

その他の不可避不純物については、特に原材料やその製造過程で何ら意識することなく不可避的に混入するものであって、例えば0.045%以下のP、0.030%以下のSなどを挙げることができる。またその分量は、合計で例えば1.0%以下に抑制される。   Other inevitable impurities are inevitably mixed without any particular attention in the raw materials and the production process thereof, and examples include P of 0.045% or less, S of 0.030% or less, and the like. it can. Moreover, the amount is suppressed to 1.0% or less in total.

本発明の耐水素性ばね用ステンレス鋼線は、このような組成でかつ前記A値を調整されたオーステナイト系ステンレス鋼からなり、通常は線径は、例えば0.05〜5mm程度の長尺状のワイヤーや線材として用いられる。前記A値が30.0%未満のものではオーステナイト相の安定化が十分に図れず、加工硬化による所定強度を得る為の伸線加工によって加工誘起マルテンサイト相を形成して耐水素性が低下することとなり、逆に40.0%を超えるものではより多くのオーステナイト相安定化元素の添加が必要で、材料費を上昇させる要因となる。より好ましくは35.0〜39.5%とする。   The stainless steel wire for hydrogen resistant springs of the present invention is made of austenitic stainless steel having such a composition and the A value adjusted, and the wire diameter is usually a long shape of about 0.05 to 5 mm, for example. Used as a wire or wire. If the A value is less than 30.0%, the austenite phase cannot be sufficiently stabilized, and a work-induced martensite phase is formed by wire drawing to obtain a predetermined strength by work hardening, resulting in a decrease in hydrogen resistance. On the contrary, if it exceeds 40.0%, it is necessary to add more austenite phase stabilizing elements, which increases the material cost. More preferably, it is 35.0 to 39.5%.

また本発明は、ばね用のステンレス鋼線を対象とし、その引張強さは1000〜2000MPaで、かつ耐力比が60〜90%を有するように冷間加工されたもので、かつその格子結晶構造が面心立方晶であることを特徴事項としている。耐力比は(〔0.2%耐力値/引張強さ〕×100%)で算出でき、その値が大きくなるに伴って耐へたり性が向上し、より安定した長寿命のばね特性を提供できる。該耐力比が60%未満のものでは柔軟すぎてばね用途には適さず、逆に90%を超えるものでは靭性が低下して疲労特性に劣るものとなり、より好ましくは65〜75%とする。なおその断面形状については、円形の線材の他、例えば楕円形や角型形状等の非円形断面のものも用途に応じて任意に選択でき、また特に断面寸法を明確にする必要がある時は、その実断面積を円形に換算した直径で示すこととする。   Further, the present invention is directed to a stainless steel wire for a spring, the tensile strength is 1000 to 2000 MPa, the cold working is performed so that the proof stress ratio is 60 to 90%, and the lattice crystal structure thereof. Is a face-centered cubic crystal. Yield ratio can be calculated by ([0.2% proof stress value / tensile strength] x 100%). As the value increases, sag resistance improves, providing more stable and long-life spring characteristics. it can. If the proof stress ratio is less than 60%, it is too soft and unsuitable for use as a spring. Conversely, if it exceeds 90%, the toughness is lowered and the fatigue properties are inferior, and more preferably 65 to 75%. As for the cross-sectional shape, in addition to a circular wire, a non-circular cross-sectional shape such as an ellipse or a square shape can be arbitrarily selected according to the application, and particularly when the cross-sectional dimensions need to be clarified. The actual cross-sectional area is indicated by a diameter converted to a circle.

前記引張強さ及び耐力比は、例えば該ワイヤーの製造過程での最終加工率、すなわち加工硬化率の調整で容易に達成できるものであり、引張強さ1000MPa未満のものではこれをばね製品にした場合に十分なばね弾性力が得られず、所定の繰返し応力負荷が困難となる。一方2000MPaを超える高強度のものでは、その為により大きな冷間加工が必要となり、それに伴って加工誘起マルテンサイト量が増加して水素脆性が生じやすくなる為、好ましくは1200〜1800MPa、更に好ましくは1300〜1600MPaとする。その測定は、例えばJIS−Z2241「金属材料引張試験方法」で行なわれ、こうして得られた鋼線横断面の顕微鏡組織写真の一例を図1に示している。 The tensile strength and yield strength ratio can be easily achieved, for example, by adjusting the final processing rate in the manufacturing process of the wire, that is, the work hardening rate. If the tensile strength is less than 1000 MPa, this is used as a spring product. In this case, a sufficient spring elastic force cannot be obtained, and a predetermined repeated stress load becomes difficult. On the other hand, in the case of a high strength exceeding 2000 MPa, a larger cold work is required, and accordingly, the amount of work-induced martensite is increased and hydrogen embrittlement is likely to occur. Therefore, preferably 1200 to 1800 MPa, more preferably The pressure is set to 1300 to 1600 MPa. The measurement is performed by, for example, JIS-Z2241 “Metal material tensile test method”, and FIG. 1 shows an example of a micrograph of the cross section of the steel wire thus obtained.

こうした特性の好ましい形態は、冷間加工でかつその結晶構造が面心立方晶を備える加工条件の範囲内で設定され、より好ましくは引張強さ1300〜1600MPaと耐力比65〜75%の両特性を備える。また更に該ワイヤーの縦断面における結晶粒の平均アスペクト比(結晶長さL/結晶太さd)が、例えば1.2〜20倍、好ましくは1.5〜8倍程度になるように調整しておくことも好ましい。   A preferable form of such characteristics is set within the range of cold working and the processing conditions in which the crystal structure includes face-centered cubic crystals, and more preferably both characteristics of tensile strength of 1300 to 1600 MPa and proof stress ratio of 65 to 75%. Is provided. Further, the average aspect ratio (crystal length L / crystal thickness d) of the crystal grains in the longitudinal section of the wire is adjusted to be, for example, 1.2 to 20 times, preferably about 1.5 to 8 times. It is also preferable to keep it.

このアスペクト比の測定は、例えばワイヤーの縦断面を100〜400倍程度に拡大した顕微鏡検査で、任意に抽出した30〜200点程度の結晶粒について行なった結果の平均値で示される。なおこの場合の結晶粒は、その検査面に確認される全ての結晶を対象とし、例えば結晶粒の軸心を外れて実際の結晶粒径より細く見られるものも含めるものとし、こうした不都合を緩和する為に、前記測定点数を増やし平均化することで調整される。   The measurement of the aspect ratio is indicated by an average value of results obtained for about 30 to 200 crystal grains arbitrarily extracted by, for example, microscopic inspection in which the longitudinal section of the wire is enlarged by about 100 to 400 times. Note that the crystal grains in this case are all the crystals that are confirmed on the inspection surface, for example, those that appear off the axis of the crystal grains and appear smaller than the actual crystal grain size, and alleviate these inconveniences. In order to do so, the number of measurement points is increased and averaged.

前記アスペクト比が1.2未満のものではばね材としての十分な強度が得られず、20倍を超えるものでは格子歪を増して水素がトラップするスペースを高めて、遅れ破壊の発生原因となり、更に好ましくは前記図1に見られるように横断面での結晶粒径が例えば2〜15μm程度のものとする。   When the aspect ratio is less than 1.2, sufficient strength as a spring material cannot be obtained, and when it exceeds 20 times, the lattice strain is increased to increase the space for trapping hydrogen, causing delayed fracture, More preferably, as shown in FIG. 1, the crystal grain size in the cross section is, for example, about 2 to 15 μm.

このような種々特性は、前記成分組成の調整とともに、例えば最終の伸線加工率を40〜80%程度とする冷間加工率との調整で可能である。該加工率が40%未満のものでは、前記強度は得られ難く、また80%以上を超えるような大きな加工率では、加工マルテンサイトが誘発しやすくなり耐水素性が低下することから、好ましくは40〜60%、より好ましくは45〜55%とする。   Such various characteristics can be achieved by adjusting the component composition and adjusting the cold drawing rate so that the final drawing rate is about 40 to 80%. When the processing rate is less than 40%, it is difficult to obtain the above strength, and when the processing rate is higher than 80% or more, processing martensite is easily induced and the hydrogen resistance is lowered. -60%, more preferably 45-55%.

この程度の加工率は、通常のばね用材料ではあまり実施されない低加工に相当し、素材状態での母相、すなわち面心立方晶をそのまま維持することから格子結晶間に加工歪に伴う空隙の形成を抑えることができ、侵入した水素の陽子(プロトン)をより安定に収容できる。なお前記格子結晶構造は、例えば前記各成分組成の分量及び加工処理条件等によって調整でき、その確認は例えばX線解析法で行なわれる。   This degree of processing rate corresponds to low processing that is not often performed with ordinary spring materials, and since the parent phase in the raw material state, that is, the face-centered cubic crystal is maintained as it is, voids due to processing strain are generated between lattice crystals. Formation can be suppressed, and invading hydrogen protons (protons) can be accommodated more stably. The lattice crystal structure can be adjusted by, for example, the amount of each component composition, processing conditions, and the like, and the confirmation is performed by, for example, an X-ray analysis method.

また本発明では、更に該ステンレス鋼線の表面に形成される不動態被膜を所定厚さに調整することも特徴事項としており、その厚さは15〜50nmとする。不動態被膜は、該ステンレス鋼を構成する構成元素、例えばFe,Cr,Ni等がその表面上で酸化し形成されるもので、特により多くの酸化クロムを含むものでは非常にタイトかつ緻密に形成でき、外界からの水素侵入の抑制を図るとともに、表面を保護して耐食性を高める効果を有する。その成形厚さが15nm未満のものでは十分なバリア効果は期待できず、50nmを超えるものではその為の別途処理を要し、効果との関係で飽和する。
In the present invention, the passive film formed on the surface of the stainless steel wire is also adjusted to a predetermined thickness, and the thickness is set to 15 to 50 nm. The passive film is formed by oxidation of the constituent elements constituting the stainless steel, such as Fe, Cr, Ni, etc. on the surface thereof, and particularly in the case of containing more chromium oxide, it is very tight and dense. It can be formed, has the effect of suppressing hydrogen intrusion from the outside and protecting the surface to enhance corrosion resistance. If the molding thickness is less than 15 nm, a sufficient barrier effect cannot be expected. If the molding thickness exceeds 50 nm, a separate treatment is required for this purpose, and the effect is saturated in relation to the effect.

例えば図2は、比較の為にCr含有量の異なる2種類のステンレス鋼((1)Fe−8Cr−10Ni合金,(2)Fe−18Cr−8Ni−Mo合金)に所定電位を付与し、形成した不動態被膜の膜厚さと設定電位との関係を示す一例で、処理条件は250℃、0.5Kmol/mのNaSo4溶液中で処理したものである。 For example, FIG. 2 shows the formation of two types of stainless steel ((1) Fe-8Cr-10Ni alloy, (2) Fe-18Cr-8Ni-Mo alloy) with different Cr contents for comparison. This is an example showing the relationship between the film thickness of the passivated film and the set potential, and the treatment conditions are those in 250 ° C. and 0.5 Kmol / m 3 Na 2 So 4 solution.

これによれば、例えば前者の低Cr合金材では約100nm程度の比較的膜厚さの厚い不動態被膜が形成されるが、その膜状態は、最初に形成される最表面層がバリアになって、その直下部分では周辺の元素を引き寄せられ、形成厚さ、皮膜組成は構成元素の分量及び不動態処理条件によって種々変化する。
According to this, for example, in the former low Cr alloy material, a relatively thick passive film having a thickness of about 100 nm is formed, but in the film state, the outermost surface layer formed first becomes a barrier. In the area immediately below, the surrounding elements are attracted, and the formation thickness and film composition vary depending on the amount of constituent elements and the passive treatment conditions.

これに対して、本発明の耐水素性ばね用ステンレス鋼線のような高Cr合金材では、不動態域での膜厚さは10〜40nm程度の薄膜であり、また本発明のように、NiやMoを含有するオーステナイト系ステンレス鋼では鋼中のCrが濃縮され、前記低Cr合金とは異なるより緻密かつタイトなCr層を形成することができる。 On the other hand, in the high Cr alloy material such as the stainless steel wire for hydrogen resistant spring of the present invention, the film thickness in the passive region is a thin film of about 10 to 40 nm. In the austenitic stainless steel containing Mo and Mo, Cr in the steel is concentrated, and a denser and tighter Cr 2 O 3 layer different from the low Cr alloy can be formed.

しかし、処理条件が過不動態域となるような環境下で得られる不動態被膜は、100nm以上の膜厚さとなり、しかもその被膜状態は該被膜中のCrがCrO 2−として溶出し、多孔質化した粗雑であり、到底水素侵入を阻止するバリア的な働きを有するものとは成り得ない。 However, the passive film obtained in an environment where the processing conditions are in the overpassive region has a thickness of 100 nm or more, and the coating state is that Cr in the film is eluted as CrO 4 2− It is porous and rough, and cannot have a barrier function to prevent hydrogen entry.

本発明では、良好な不動態被膜を備えるよう、その膜厚さを15〜50nmとしており、その測定は、例えばエリプソメトリー、オージェ分析等による方法、電界放射型透過電子顕微鏡によるSTEM像から求める方法、グロー放電発光法分析(GDS)によって深さ方向に沿って元素分布を求める方法など、種々の高度理化学的手法が採用できる。
In the present invention, the film thickness is set to 15 to 50 nm so as to provide a good passive film, and the measurement is performed, for example, by a method using ellipsometry, Auger analysis or the like, or a method obtained from a STEM image by a field emission transmission electron microscope. Various advanced physicochemical methods such as a method of obtaining an element distribution along the depth direction by glow discharge emission spectrometry (GDS) can be employed.

こうした不動態域での被膜は例えば空気中の自然状態でも形成できるが、特に硝酸などの酸液中に浸漬する化学的処理によるものでは、被膜状態が安定した良好な不動態被膜が得られ、比較的厚さが薄くても、その全面に一様に緻密かつタイトな被膜が形成できる。   A film in such a passive region can be formed, for example, in a natural state in the air, but a good passive film with a stable film state can be obtained especially by chemical treatment immersed in an acid solution such as nitric acid. Even if the thickness is relatively small, a uniformly dense and tight film can be formed on the entire surface.

さらに前記不動態被膜は、その成分組成がCr/(Fe+Cr)=0.5以上かつ0.90以下のものであることが好ましい。これによって緻密硬質なCrの特性を水素侵入のバリア層として応用でき、本発明のような高Cr材を用いるステンレス鋼では比較的容易に達成可能である。なお該不動態被膜の状態を確認するには、例えば表面分析装置であるX線光電子分光分析装置を用いて、不働態被膜のCrとFeとの各ピーク面積から求めることが可能である。 Further, the passive film preferably has a component composition of Cr 2 O 3 / (Fe 2 O 3 + Cr 2 O 3 ) = 0.5 or more and 0.90 or less. As a result, the characteristics of dense and hard Cr 2 O 3 can be applied as a hydrogen intrusion barrier layer, and can be achieved relatively easily in stainless steel using a high Cr material as in the present invention. In order to confirm the state of the passive film, it is obtained from the peak areas of Cr 2 O 3 and Fe 2 O 3 of the passive film using, for example, an X-ray photoelectron spectroscopic analyzer which is a surface analyzer. Is possible.

また本発明のステンレス鋼線は、その用途をばね用とし、その成形する際の成形性,潤滑性を高める為に、例えば線の表面上にNi、Cu等の金属被覆を行なうことも好ましい。金属被膜には、例えばNiメッキではその線径の(0.5〜3)/1000倍、即ち0.5〜10μm程度の厚さとし、その被膜処理は、通常のばね用ステンレス鋼線と同様に最終伸線加工前の素材状態の段階で行うことで、これを伸線加工用の潤滑被膜として用いることができる。こうした特性をより良好にする為に、例えば生地マトリックス中に平均粒子径0.1〜5μm程度の窒化物や酸化物などの微細粒子を分布させることも好ましく、分布量としては例えば0.05〜10容積%程度とする。   In addition, the stainless steel wire of the present invention is preferably used for springs, and in order to improve the formability and lubricity at the time of forming, for example, the surface of the wire is preferably coated with a metal such as Ni or Cu. The metal coating is, for example, Ni plating with a thickness of (0.5-3) / 1000 times the wire diameter, that is, about 0.5-10 μm, and the coating treatment is the same as that of a normal stainless steel wire for springs. By carrying out in the stage of the raw material state before the final wire drawing, this can be used as a lubricating coating for wire drawing. In order to make these characteristics better, it is also preferable to distribute fine particles such as nitrides and oxides having an average particle size of about 0.1 to 5 μm in the dough matrix. About 10% by volume.

つぎに、本発明の耐水素性ばね製品は、前記オーステナイトステンレス鋼線を例えばばね成形機によってトーションばね、コイルばね形状に成形され、また必要ならば例えば300〜600℃程度の低温でテンパー処理してばね性を高める他、前記メッキ層を最終的に除去する表面処理を更に行うことができる。特に前記NiメッキやCuメッキは例えば硝酸液での洗浄処理が可能なことから、その処理で再度不動態被膜の再形成も可能である。   Next, in the hydrogen resistant spring product of the present invention, the austenitic stainless steel wire is formed into a torsion spring or coil spring shape by a spring forming machine, for example, and if necessary, tempered at a low temperature of about 300 to 600 ° C. In addition to enhancing the spring property, a surface treatment for finally removing the plated layer can be further performed. In particular, since the Ni plating and Cu plating can be washed with, for example, a nitric acid solution, the passive film can be re-formed again by the treatment.

ばねの形状や寸法等は、使用する用途、設置面積、付設構造を考慮した種々形態に成形され、その具体例として例えば水素ガス供給用ノズル部品用のばね製品では、線径0.5〜3mm,外径10〜30mmの、全長10〜50mm程度に形成された圧縮又は引張りコイルばねとして用いられる。   The shape, dimensions, etc. of the spring are molded into various forms taking into consideration the intended use, installation area, and attachment structure. As a specific example, for example, a spring product for hydrogen gas supply nozzle parts has a wire diameter of 0.5 to 3 mm. , Used as a compression or tension coil spring having an outer diameter of 10 to 30 mm and a total length of about 10 to 50 mm.

またこうした用途では、例えば35〜100MPa(標準70MPa)の高圧水素環境下での使用においても、本発明に係わる前記ステンレス鋼線でなるばね製品はその組成を調整したオーステナイト系ステンレス鋼線で、かつその格子結晶が面心立方晶であることから、仮に材料内部に前記原子状水素(プラトン)が侵入しても、その影響を減じることができる。   In such applications, for example, even in use under a high pressure hydrogen environment of 35 to 100 MPa (standard 70 MPa), the spring product made of the stainless steel wire according to the present invention is an austenitic stainless steel wire whose composition is adjusted, and Since the lattice crystal is a face-centered cubic crystal, even if the atomic hydrogen (platon) intrudes into the material, the influence can be reduced.

本発明に係わるばね製品は、前記いずれか構成のステンレス鋼線で形成され、その結晶構造は面心立方晶を有し、かつ負荷応力500MPa、応力振幅180MPaで繰返し応力負荷した時の疲労寿命が1.0×10回以上、好ましくは10回以上、即ち1000万回以上の繰返し使用に耐え得る特性を有するものを対象とし、その繰返し負荷速度は例えば30回/secの条件で評価することとしている。 The spring product according to the present invention is formed of the stainless steel wire having any one of the structures described above, and its crystal structure has a face-centered cubic crystal, and has a fatigue life when subjected to repeated stress loading with a load stress of 500 MPa and a stress amplitude of 180 MPa. 1.0 × 10 6 times or more, preferably 10 7 times or more, that is, those having characteristics capable of withstanding repeated use of 10 million times or more, and the repeated load speed is evaluated under the condition of 30 times / sec, for example. I am going to do that.

なお前記負荷応力は、通常用いるワイヤーの弾性特性(耐力)に応じて設定されるものであるが、本発明では便宜上前記設定応力:500MPa、応力振幅:±180MPaの条件で評価することとし、その破断までの繰返し回数が測定される。   The load stress is set according to the elastic characteristics (proof stress) of the wire that is normally used. In the present invention, for the sake of convenience, the set stress is 500 MPa and the stress amplitude is ± 180 MPa. The number of repetitions until failure is measured.

本発明に係わる実施例のステンレス鋼材(種類)と、比較例材a,bとして通常のSUS304及びSUS316ステンレス鋼を各々溶解し、熱間圧延して各5.5mmの線材ロッドを製造し、これを素線として連続冷間伸線機での合金ダイス引き加工しながら最終線径2.0mmに細径化し、その最終加工率を0%(軟質),50%(半硬質),75%(硬質)になるように調整した各試験用ワイヤーを得た。
Stainless steel materials of the examples according to the present invention ( two types) and normal SUS304 and SUS316 stainless steel as the comparative example materials a and b were respectively melted and hot rolled to produce each 5.5 mm wire rod, Using this as an element wire, the final wire diameter was reduced to 2.0 mm while alloy die drawing with a continuous cold drawing machine, and the final processing rate was 0% (soft), 50% (semi-hard), 75%. Each test wire adjusted to be (hard) was obtained.

加工率0%は軟質品で、最終伸線加工後にArガス中で温度1030℃の固溶化熱処理したものであり、他の硬質及び半硬質の試料は、予め計算で求めた中間線径段階で前記と同様の固溶化熱処理を行った後に、所定加工率で最終冷間伸線加工を行なったものである。各ステンレス鋼材の化学成分を表1に示す。   The processing rate is 0%, which is a soft product, which has been subjected to solution heat treatment at a temperature of 1030 ° C. in Ar gas after the final wire drawing, and other hard and semi-hard samples are in the intermediate wire diameter stage determined in advance by calculation. After performing the same solution heat treatment as described above, the final cold wire drawing is performed at a predetermined processing rate. Table 1 shows the chemical composition of each stainless steel material.

《試験1:特性試験》
これら線径2.0mmの各試験線材の特性を評価する一次試験として、JIS−Z2241による引張強さと0.2%耐力、伸び、絞り、及びねじり試験機による破断までの捻回回数を求めた。ねじり試験は、高千穂精機(株)製:電気式ねじり試験機によりばね製品での使用状態を把握する為に、予め温度480℃×1Hrのテンパー処理をした長さ200mmに切断したワイヤー試料を用い、その一端側を固定し他端側を2回/minの条件で捩りながら、破断するまでの捩り回数を求めたものであり、各試験結果を表2に示している。
<< Test 1: Characteristic test >>
As a primary test for evaluating the characteristics of each test wire having a diameter of 2.0 mm, the tensile strength and 0.2% yield strength according to JIS-Z2241, elongation, drawing, and the number of twists until breakage by a torsion tester were obtained. . The torsion test was made by Takachiho Seiki Co., Ltd .: using a wire sample cut to a length of 200 mm in advance, which was tempered at a temperature of 480 ° C. × 1 Hr in order to grasp the state of use in a spring product by an electric torsion tester. The number of twists until breakage was determined while fixing one end side and twisting the other end side at 2 times / min. Table 2 shows the results of each test.

この結果に見られるように、本発明に係る実施例材A〜は、いずれも比較例aのSUS304及び比較例bのSUS316材等に比して強度及び捻回特性に優れ、例えば実施例材Aの50%加工材では、SUS304より引張強さで約200MPa、絞り特性10%程度向上し、また捻回値についても36回から76回と2倍以上の特性が得られている。特に加工率50%の加工材では引張強さ1400MPaで耐力比70〜75%を備え、捻回特性にも優れることから、ばね用材料としての有効性が見込まれるものであった。
As can be seen from these results, each of the example materials A to B according to the present invention is superior in strength and twisting characteristics as compared with the SUS304 material of the comparative example a and the SUS316 material of the comparative example b. In the 50% processed material of material A, the tensile strength is improved by about 200 MPa and the drawing property is improved by about 10% from SUS304, and the twist value is also 36 times to 76 times, which is more than doubled. In particular, a processed material with a processing rate of 50% has a tensile strength of 1400 MPa, a yield strength ratio of 70 to 75%, and excellent twist characteristics, so that it is expected to be effective as a spring material.

またこの実施例材の格子結晶構造を、島津製作所製/VG108型X線回析装置を用いて観察した結果、いずれの加工率のものも面心立方晶(fcc)を有するオーステナイト系ステンレス鋼であることが確認された。更にオージェ分光分析装置によって線材表面の不働態被膜を測定した結果、厚さ15〜50nmでCr/(Fe+Cr)が平均0.68の結果であり、SUS304の比較例材aは体心立方構造で、被膜厚さ35〜65nmであった。 Moreover, as a result of observing the lattice crystal structure of this example material using a Shimadzu Corporation / VG108 type X-ray diffraction apparatus, all of the processing rates are austenitic stainless steels having face centered cubic (fcc). It was confirmed that there was. Furthermore, as a result of measuring the passive state film on the surface of the wire with an Auger spectroscopic analyzer, the result was an average of 0.68 for Cr 2 O 3 / (Fe 2 O 3 + Cr 2 O 3 ) at a thickness of 15 to 50 nm. The comparative example material a had a body-centered cubic structure and a film thickness of 35 to 65 nm.

《試験2 水素チャージ試験》
次に各線材の耐水素性を確認する為の第二次試験として水素チャージ試験を行なった。試験は、各線材を標点間距離100mmでかつその両端を1000MPaの応力で引張るようにした専用冶具に取り付けて、該応力を負荷した状態のまま圧力容器内に収容して、室内に水素を供給した。試験条件は、水素供給圧30MPa×100Hrの条件で、かつ加速試験の為に温度200℃に加熱する加速試験で行った。こうして水素吸収させた後、各線材試料を取り出してペンチで挟持し、90°に折り曲げて破断の有無を確認する折り曲げ試験と、引張り試験による引張強さ及び絞り特性の2種類で行い、曲げ応力と引張り応力の両面から性能評価を行なった。その試験結果を表3に示している。
<< Test 2 Hydrogen Charge Test >>
Next, a hydrogen charge test was conducted as a secondary test for confirming the hydrogen resistance of each wire. In the test, each wire was attached to a dedicated jig with a distance of 100 mm between the gauge points and both ends of which were pulled with a stress of 1000 MPa, accommodated in a pressure vessel with the stress applied, and hydrogen was introduced into the room. Supplied. The test conditions were a hydrogen supply pressure of 30 MPa × 100 Hr and an accelerated test in which the temperature was heated to 200 ° C. for the accelerated test. After absorbing the hydrogen in this way, each wire sample is taken out and sandwiched with pliers, bent at 90 ° to confirm the presence or absence of breakage, and tensile strength and drawing characteristics by tensile test, bending stress Performance evaluation was performed from both sides of tensile stress. The test results are shown in Table 3.

これら結果から明らかなように、本発明に係わる実施例材、いずれも水素脆性試験前の線材特性とあまり大きな差異は見られず、絞り試験では比較例材に比して減少率が小さく、また曲げ試験でも亀裂等の表面欠陥は認められなかった。したがって、本発明に係わるステンレス鋼線は十分な耐水素性を備え、また残留水素量も20〜40PPM程度以下で、比較材の55〜80PPMに比して少ないことが確認できた。   As is clear from these results, all of the example materials according to the present invention showed no significant difference from the wire material properties before the hydrogen embrittlement test, and the reduction rate was smaller than the comparative example material in the drawing test. No surface defects such as cracks were observed in the bending test. Therefore, it was confirmed that the stainless steel wire according to the present invention has sufficient hydrogen resistance, and the residual hydrogen amount is about 20 to 40 PPM or less, compared with 55 to 80 PPM of the comparative material.

《試験3:ばね成形・疲労特性試験》
次に、本発明の前記各実施例材及び比較材aの両線材の硬質と半硬質材の各々について、さらに次のコイリング試験と、得られたばね製品の疲労試験を行ない特性評価した。
<< Test 3: Spring forming and fatigue characteristics test >>
Next, the following coiling test and the fatigue test of the obtained spring product were further performed on each of the hard and semi-hard materials of each of the examples and comparative materials a of the present invention to evaluate the characteristics.

コイリング試験は、次の仕様の圧縮コイルばねをばね成形機(シンコーマシナリー社製:VF712EL型)で約3000個連続成形処理した時のばね製品の自由長のバラツキを測定し、一方、疲労試験は成形コイルばねを温度250℃×1Hrの条件で低温熱処理したものである。   The coiling test measures the variation in the free length of spring products when approximately 3000 compression coil springs of the following specifications are continuously molded by a spring molding machine (manufactured by Shinko Machinery: VF712EL type). The formed coil spring is heat-treated at a low temperature under the condition of a temperature of 250 ° C. × 1 Hr.

コイル平均径:18.5mm
総巻数 :6.5
有効巻数 :4.5
ばね自由長 :47mm
Coil average diameter: 18.5mm
Total number of turns: 6.5
Effective number of turns: 4.5
Spring free length: 47mm

ばね疲労試験は、前記成形コイルばねを前記試験2と同様の水素容器内にセットして、30MPaの水素加圧をしながら温度200℃×250時間に亙って暴露する促進試験を行なったものを試験試料とし、これをばね疲労試験機にセットして、水素チャージ処理の有無に伴うコイルばねの疲労特性を評価するもので、試験ばねは各々初期応力として平均500N/mmの圧縮応力を負荷した状態でセットし、このばねを各々応力振幅200〜300N/mm2の負荷を毎秒30回の高速で連続負荷する繰返し試験を行ない、疲労破断に至るまでの回数を求めることで行なわれる。
前記ばね形状への成形加工性はいずれも良好であり、特に問題は見られなかった。
In the spring fatigue test, the molded coil spring was set in the same hydrogen container as in Test 2, and an accelerated test was performed in which exposure was performed at a temperature of 200 ° C. for 250 hours while applying 30 MPa of hydrogen. Is set in a spring fatigue testing machine to evaluate the fatigue characteristics of the coil spring with or without hydrogen charge treatment. Each test spring has an initial compressive stress of 500 N / mm 2 on average. This test is performed by setting the springs in a loaded state, and performing a repeated test in which a load having a stress amplitude of 200 to 300 N / mm 2 is continuously applied at a high speed of 30 times per second, and determining the number of times until fatigue fracture occurs.
The formability into the spring shape was good, and no particular problem was found.

疲労試験の結果は図3、図4に示しており、本発明の実施例Aの特に半硬質材では、前記水素チャージしたコイルばねでは1.0E+06回の繰返し回数が確認でき、硬質材及び比較材の図4に示すものより優れた寿命特性を備えるものであった。
The results of the fatigue test are shown in FIG . 3 and FIG. 4. In particular, in the semi-hard material of Example A of the present invention, the hydrogen-charged coil spring can confirm the number of repetitions of 1.0E + 06 times. The material had life characteristics superior to those shown in FIG.

次に、前記不動態被膜の効果を見るために、前記試験例1と同様に表1の合金材種類を各々溶解、熱間圧延、冷間伸線しながら細径化して、最終加工率が63%になるように調整した中間線材を、Arガス雰囲気中で温度1000〜1080℃で加熱する固溶化熱処理を行った後、所定加工率で冷間伸線加工して目的とする2.0mmのワイヤーとし、更に硝酸溶液での表面処理と水洗乾燥を経て、不働態被膜の形成を促進したワイヤー製品を得た。
Next, in order to see the effect of the passive film, the diameter of the two alloy materials shown in Table 1 was reduced while melting, hot rolling, and cold drawing in the same manner as in Test Example 1 to obtain the final processing rate. The intermediate wire adjusted to 63% is subjected to a solution heat treatment in which the intermediate wire is heated in an Ar gas atmosphere at a temperature of 1000 to 1080 ° C., and then cold drawn at a predetermined processing rate to be the target. A wire product that promoted the formation of a passive film was obtained by using a 0 mm wire, and further surface treatment with a nitric acid solution and washing and drying.

その結晶構造は面心立方晶で、引張強さ1330〜1470MPaかつ耐力比72〜77%の特性を有するものであった。またワイヤーの表面には厚さ40nm程度の不働態被膜が認められた。更にその組成はCr/(Fe+Cr)が0.90〜0.95であり、より緻密な表面被膜であることが確認された。 The crystal structure was face-centered cubic, and had a tensile strength of 1330 to 1470 MPa and a yield strength ratio of 72 to 77%. Moreover, the passive film about 40 nm thick was recognized on the surface of the wire. Further, the composition was Cr 2 O 3 / (Fe 2 O 3 + Cr 2 O 3 ) of 0.90 to 0.95, confirming that it was a denser surface coating.

そこで、これを前記と同様に30MPaの高圧水素環境中に約10時間放置して、積極的に水素吸収させた後、取り出してワイヤー内部の残留水素量を測定したが、20PPM程度の微量レベルであった。   Therefore, this was left in a high-pressure hydrogen environment of 30 MPa for about 10 hours in the same manner as described above, and after actively absorbing hydrogen, it was taken out and the amount of residual hydrogen inside the wire was measured. there were.

前記実施例2と同様に、更に表4の組成を有する合金線(試料D,E,F)3種類を各々溶解、熱間圧延、冷間伸線を行いながら最終加工率をもう少し高めた63%にした中間線材を、Ar雰囲気中で温度1000℃での固溶化熱処理した。そしてこれを無電解Niめっき装置によって表面に厚さ2〜3μmのNiめっきを形成して前記加工率で冷間伸線加工を行ない、線径2.0mmのNi被覆鋼線を得た。
In the same manner as in Example 2, the final processing rate was slightly increased while further melting, hot rolling, and cold drawing each of three types of alloy wires (samples D, E, and F ) having the compositions shown in Table 4 63. % Was subjected to solution heat treatment at a temperature of 1000 ° C. in an Ar atmosphere. And this was formed by plating an Ni plating having a thickness of 2 to 3 μm on the surface by an electroless Ni plating apparatus, and cold-drawing was performed at the above-mentioned processing rate to obtain a Ni-coated steel wire having a wire diameter of 2.0 mm.

その際、Niめっきは、その前処理として硝酸溶液での表面活性処理によって、ステンレス鋼線の表面には厚さ30〜50nmの不動態被膜が形成され、しかも該不動態被膜はCr/(Fe+Cr)が0.70〜0.93の範囲内のものであった。 At that time, the Ni plating is subjected to surface activation treatment with a nitric acid solution as a pretreatment to form a passive film having a thickness of 30 to 50 nm on the surface of the stainless steel wire, and the passive film is Cr 2 O 3. / (Fe 2 O 3 + Cr 2 O 3 ) was within the range of 0.70 to 0.93.

つぎに、これら線材を直線状態のまま温度400℃×1Hrの条件でテンパー処理するとともに、さらに700MPaの曲げ応力を付加した状態のまま、70MPaの高圧水素容器内に放置して水素中に晒した後、取り出して種々特性を評価した。その結果を表5に一覧しており、水素残留量も20〜25PPM程度で、前記各試験と遜色するものではなかった。     Next, these wires were tempered in a straight line state at a temperature of 400 ° C. × 1 Hr, and further exposed to hydrogen by being left in a 70 MPa high-pressure hydrogen container with a 700 MPa bending stress applied. Then, it was taken out and various characteristics were evaluated. The results are listed in Table 5. The residual amount of hydrogen is about 20 to 25 PPM, which is not inferior to the above tests.

以上の各実施例からも理解されるように、本発明はばね特性と耐水素性に優れたばね用ステンレス鋼線の提供が可能となり、水素環境とりわけ高圧環境下で使用されるばね材料としての用途展開が可能であり、産業上極めて有益である。   As can be understood from the above embodiments, the present invention makes it possible to provide a stainless steel wire for springs excellent in spring characteristics and hydrogen resistance, and the application development as a spring material used in a hydrogen environment, particularly in a high pressure environment. Is possible, and it is extremely beneficial to the industry.

本発明に係わる実施例線材の顕微鏡組織写真の一例である。It is an example of the microscope structure photograph of the Example wire concerning this invention. ステンレス鋼の組成による不動態被膜の変化を説明するグラフである。It is a graph explaining the change of the passive film by the composition of stainless steel. 本発明実施例品のばね疲労試験結果の一例で、(A)は硬質状態、(B)は半硬質状態を示す線図である。It is an example of the spring fatigue test result of this invention Example goods, (A) is a hard state, (B) is a diagram which shows a semi-hard state. 比較例品のばね疲労試験結果の一例で、(A)はSUS304材の硬質状態であり、(B)はSUS316線材の特性を示す線図である。It is an example of the spring fatigue test result of a comparative example product, (A) is a hard state of SUS304 material, (B) is a diagram which shows the characteristic of SUS316 wire.

Claims (10)

質量%で、C:0.08%以下、Si:1.0%以下、Mn:4.0〜15.0%、Ni:5.0〜15.0%、Cr:18.0〜25.0%、Mo:0.5〜3.0%、N:0.3〜0.8%を含み、かつ残部Feと不可避不純物とからなるとともに、次式(1)のA値を30.0〜40.0%に調整したオーステナイト系ステンレス鋼で構成され、かつ
引張強さは1000〜2000MPa、該引張強さと0.2%耐力との比で示される耐力比(〔0.2%耐力/引張強さ〕×100%)を60〜90%とする冷間加工がなされ、その加工後の格子結晶構造が面心立方晶(fcc)を有することを特徴とする耐水素性ばね用ステンレス鋼線。
A=0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6(C+N)+Ni…(1)
In mass%, C: 0.08% or less, Si: 1.0% or less, Mn: 4.0-15.0%, Ni: 5.0-15.0%, Cr: 18.0-25. 0%, Mo: 0.5-3.0%, N: 0.3-0.8%, and the balance is Fe and inevitable impurities, and the A value of the following formula (1) is 30. It is composed of austenitic stainless steel adjusted to 0 to 40.0%, and the tensile strength is 1000 to 2000 MPa, and the yield strength ratio ([0.2% yield strength / Tensile strength] × 100%) is cold worked to 60 to 90%, and the lattice crystal structure after the work has face centered cubic (fcc), stainless steel for hydrogen resistant springs line.
A = 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si + 12.6 (C + N) + Ni (1)
前記オーステナイト系ステンレス鋼は、
質量%で、C:0.005〜0.05%、Si:0.05〜0.40%、Mn:4.5〜8.0%、Ni:8.0〜11.0%、Cr:20.0〜25.0%、Mo:0.8〜3.0%、N:0.4〜0.65%を含み、かつ残部Feと不可避不純物とからなることを特徴とする請求項1に記載の耐水素性ばね用ステンレス鋼線。
The austenitic stainless steel is
In mass%, C: 0.005 to 0.05%, Si: 0.05 to 0.40%, Mn: 4.5 to 8.0%, Ni: 8.0 to 11.0%, Cr: 20.0~25.0%, Mo: 0.8~3.0%, N: comprises 0.4 to 0.65%, and the balance being composed of Fe and inevitable impurities claim The stainless steel wire for hydrogen resistant springs according to 1.
質量%で、C:0.08%以下、Si:1.0%以下、Mn:4.0〜15.0%、Ni:5.0〜15.0%、Cr:18.0〜25.0%、Mo:0.5〜3.0%、N:0.3〜0.8%、Ti:0.001〜0.1%、Mg:0.001〜0.02%を含み、かつ残部がFeと不可避不純物とからなるとともに、次式(1)のA値を30.0〜40.0%に調整したオーステナイト系ステンレス鋼で構成され、かつ
引張強さは1000〜2000MPa、該引張強さと0.2%耐力との比で示される耐力比(〔0.2%耐力/引張強さ〕×100%)を60〜90%とする冷間加工がなされ、その加工後の格子結晶構造が面心立方晶(fcc)を有することを特徴とする耐水素性ばね用ステンレス鋼線。
A=0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6(C+N)+Ni…(1)
In mass%, C: 0.08% or less, Si: 1.0% or less, Mn: 4.0-15.0%, Ni: 5.0-15.0%, Cr: 18.0-25. 0%, Mo: 0.5-3.0%, N: 0.3-0.8%, Ti: 0.001-0.1%, Mg: 0.001-0.02%, and The balance is composed of Fe and inevitable impurities, and is composed of austenitic stainless steel in which the A value of the following formula (1) is adjusted to 30.0 to 40.0%, and the tensile strength is 1000 to 2000 MPa. Cold working is performed with a yield strength ratio ([0.2% yield strength / tensile strength] × 100%) indicated by a ratio of strength to 0.2% yield strength of 60 to 90%. A stainless steel wire for a hydrogen-resistant spring, characterized in that the structure has face-centered cubic (fcc).
A = 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si + 12.6 (C + N) + Ni (1)
質量%で、C:0.08%以下、Si:1.0%以下、Mn:4.0〜15.0%、Ni:5.0〜15.0%、Cr:18.0〜25.0%、Mo:0.5〜3.0%、N:0.3〜0.8%、Al:0.005〜0.05%を含み、かつ残部がFeと不可避不純物とからなるとともに、次式(1)のA値を30.0〜40.0%に調整したオーステナイト系ステンレス鋼で構成され、かつIn mass%, C: 0.08% or less, Si: 1.0% or less, Mn: 4.0-15.0%, Ni: 5.0-15.0%, Cr: 18.0-25. 0%, Mo: 0.5-3.0%, N: 0.3-0.8%, Al: 0.005-0.05%, and the balance consists of Fe and inevitable impurities, It is composed of austenitic stainless steel in which the A value of the following formula (1) is adjusted to 30.0 to 40.0%, and
引張強さは1000〜2000MPa、該引張強さと0.2%耐力との比で示される耐力比(〔0.2%耐力/引張強さ〕×100%)を60〜90%とする冷間加工がなされ、その加工後の格子結晶構造が面心立方晶(fcc)を有することを特徴とする耐水素性ばね用ステンレス鋼線。  The tensile strength is 1000 to 2000 MPa, and the yield strength ratio ([0.2% yield strength / tensile strength] × 100%) indicated by the ratio between the tensile strength and 0.2% yield strength is 60 to 90% cold. A stainless steel wire for a hydrogen resistant spring, which is processed and has a lattice crystal structure having face-centered cubic (fcc) after the processing.
A=0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6(C+N)+Ni…(1)  A = 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si + 12.6 (C + N) + Ni (1)
質量%で、C:0.08%以下、Si:1.0%以下、Mn:4.0〜15.0%、Ni:5.0〜15.0%、Cr:18.0〜25.0%、Mo:0.5〜3.0%、N:0.3〜0.8%、V:0.005〜0.5%を含み、かつ残部がFeと不可避不純物とからなるとともに、次式(1)のA値を30.0〜40.0%に調整したオーステナイト系ステンレス鋼で構成され、かつIn mass%, C: 0.08% or less, Si: 1.0% or less, Mn: 4.0-15.0%, Ni: 5.0-15.0%, Cr: 18.0-25. 0%, Mo: 0.5-3.0%, N: 0.3-0.8%, V: 0.005-0.5%, and the balance consists of Fe and inevitable impurities, It is composed of austenitic stainless steel in which the A value of the following formula (1) is adjusted to 30.0 to 40.0%, and
引張強さは1000〜2000MPa、該引張強さと0.2%耐力との比で示される耐力比(〔0.2%耐力/引張強さ〕×100%)を60〜90%とする冷間加工がなされ、その加工後の格子結晶構造が面心立方晶(fcc)を有することを特徴とする耐水素性ばね用ステンレス鋼線。  The tensile strength is 1000 to 2000 MPa, and the yield strength ratio ([0.2% yield strength / tensile strength] × 100%) indicated by the ratio between the tensile strength and 0.2% yield strength is 60 to 90% cold. A stainless steel wire for a hydrogen resistant spring, which is processed and has a lattice crystal structure having face-centered cubic (fcc) after the processing.
A=0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6(C+N)+Ni…(1)  A = 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si + 12.6 (C + N) + Ni (1)
前記引張強さが1300〜1600MPaで、耐力比が65〜75%である請求項1〜5のいずれかに記載の耐水素性ばね用ステンレス鋼線。 The stainless steel wire for a hydrogen resistant spring according to any one of claims 1 to 5, wherein the tensile strength is 1300 to 1600 MPa and the yield ratio is 65 to 75% . 前記オーステナイト系ステンレス鋼は、その表面上の不動態被膜が厚さ15〜50nmに調整されたものである請求項1〜5のいずれかに記載の耐水素性ばね用ステンレス鋼線。 The stainless steel wire for a hydrogen resistant spring according to any one of claims 1 to 5, wherein the austenitic stainless steel has a passive film on its surface adjusted to a thickness of 15 to 50 nm . 表面にNi又はCuの金属被覆を具える請求項1〜7のいずれかに記載耐水素性ばね用ステンレス鋼線。The stainless steel wire for a hydrogen resistant spring according to any one of claims 1 to 7, wherein the surface is provided with a metal coating of Ni or Cu. 請求項1〜8のいずれかに記載の耐水素性ばね用ステンレス鋼線を用いてばね形状に成形され、かつその格子結晶構造は面心立方晶を有するとともに、設定負荷応力500MPa及び応力振幅±180MPaの条件で繰返し試験した時のばね疲労特性が、1.0×10 回以上であることを特徴とする耐水素性ばね製品。 A stainless steel wire for a hydrogen resistant spring according to any one of claims 1 to 8, which is formed into a spring shape and has a lattice crystal structure having a face-centered cubic crystal, a set load stress of 500 MPa and a stress amplitude of ± 180 MPa. A spring-resistant spring product characterized by having a spring fatigue characteristic of 1.0 × 10 6 times or more when repeatedly tested under the conditions of 35〜100MPaの高圧水素環境下で前記ばね疲労特性を有することを特徴とする請求項9に記載の耐水素性ばね製品。The hydrogen-resistant spring product according to claim 9, wherein the spring-resistant spring product has the spring fatigue property in a high-pressure hydrogen environment of 35 to 100 MPa.
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