JP2003105505A - High fatigue strength and high rigidity steel, and production method therefor - Google Patents
High fatigue strength and high rigidity steel, and production method thereforInfo
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- JP2003105505A JP2003105505A JP2001302998A JP2001302998A JP2003105505A JP 2003105505 A JP2003105505 A JP 2003105505A JP 2001302998 A JP2001302998 A JP 2001302998A JP 2001302998 A JP2001302998 A JP 2001302998A JP 2003105505 A JP2003105505 A JP 2003105505A
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- fatigue strength
- rigidity steel
- high rigidity
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、高い剛性と共に高
い強度、特に疲労強度が要求される機械構造用部材等に
用いられる高疲労強度・高剛性鋼とその製造方法に関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high fatigue strength / high rigidity steel used for a machine structural member which requires high rigidity and high strength, especially fatigue strength, and a manufacturing method thereof.
【０００２】[0002]
【従来の技術】鉄鋼材料は、建築物、輸送用機器、各種
機械等の構造物を維持するために用いられる機械構造部
材として最も多く使用されている。これら構造物を設計
する際に求められる重要な特性として、剛性と強度、特
に疲労強度があげられる。剛性や強度、特に疲労強度の
高い材料を使用することによって、構造物の耐用強度が
向上し、信頼性の高い構造物を得ることができる。ま
た、剛性や疲労強度の高い材料を構造物に用いること
は、それだけ使用する材料も少なくすることができるの
で、例えば、自動車、鉄道等の輸送車両に適用すると、
輸送車両の軽量化を達成することができ、その結果、燃
費向上による省エネルギー化、材料の節約による省資源
化を図ることができる。2. Description of the Related Art Steel materials are most often used as mechanical structural members used for maintaining structures such as buildings, transportation equipment, and various machines. Rigidity and strength, especially fatigue strength, are important properties required when designing these structures. By using a material having high rigidity and strength, particularly fatigue strength, the durable strength of the structure is improved, and a highly reliable structure can be obtained. Further, by using a material having high rigidity and fatigue strength for a structure, it is possible to reduce the amount of material used, so that when applied to a transportation vehicle such as an automobile or a railroad,
The weight of the transportation vehicle can be reduced, and as a result, energy can be saved by improving fuel efficiency and resources can be saved by saving materials.
【０００３】上記のような機械構造部材に用いられる鉄
鋼材料は、各種合金成分の添加や鉄鋼材料の組織改善等
によって特性改善が試みられてきた。これらの方法によ
って、鉄鋼材料の強度は、大幅に改善されたが、剛性の
向上については必ずしも十分とは言えない。剛性は材料
が本来有している物性であるため、上記のような方法で
は、剛性の向上すなわちヤング率の向上は容易でない。
しかし、ヤング率の向上は、輸送車両の軽量化を始めと
して、構造物等の設計に際し大きなメリットが得られる
ので、鉄鋼材料のヤング率を一般的な約２００ＧＰａレ
ベルから１０％程度以上高めることが望まれてきた。The properties of steel materials used for the above-mentioned mechanical structural members have been tried to improve by adding various alloy components and improving the structure of steel materials. Although the strength of the steel material is significantly improved by these methods, the improvement of the rigidity is not always sufficient. Since rigidity is a physical property that a material originally has, it is not easy to improve rigidity, that is, Young's modulus by the above method.
However, the improvement of the Young's modulus has a great advantage in designing structures such as weight reduction of transportation vehicles. Therefore, it is possible to increase the Young's modulus of a steel material from the general level of about 200 GPa to about 10% or more. Has been desired.
【０００４】こうした需要に沿うべく、鉄鋼材料の剛性
向上に関して種々の研究がなされ、多くの提案がなされ
ている。例えば、粉末冶金法による鉄鋼材料の剛性の向
上手段が数多く提案されており、これらの方法は、鋼の
マトリックス中へ高剛性を有する化合物を多量に添加す
るものである。例えば、特開平７−１８８８７４号公報
や特開平７−２５２６０９号公報では、マトリックス粉
末と高剛性を有する４ａ族、５ａ族の元素を主体とする
ホウ化物の粉末との混合粉を使用し、これを成形し焼結
させることにより、高剛性の化合物を分散させた鋼が得
られることを開示している。In order to meet such demands, various studies have been made and many proposals have been made for improving the rigidity of steel materials. For example, many means for improving the rigidity of steel materials by powder metallurgy have been proposed, and these methods add a large amount of a compound having high rigidity to the matrix of steel. For example, in JP-A-7-188874 and JP-A-7-252609, a mixed powder of a matrix powder and a boride powder mainly composed of a group 4a group and a group 5a element having high rigidity is used. It is disclosed that a steel in which a high-rigidity compound is dispersed can be obtained by molding and sintering.
【０００５】さらに、メカニカルアロイング法を採用す
れば、多量の高剛性化合物をマトリックス中に均一に分
散させた鋼が得られることも報告されている（特開平７
−１８８８７４号公報、特開平７−２５２６０９号公報
および特開平５−２３９５０４公報等参照）。しかし、
これらの技術は、粉末冶金法を適用するものであって、
その工程の複雑さからコストが高くなるという問題があ
った。Further, it has been reported that a steel in which a large amount of a high-rigidity compound is uniformly dispersed in a matrix can be obtained by adopting the mechanical alloying method (Japanese Patent Laid-Open Publication No. Hei 7 (1998)).
No. 188874, Japanese Patent Application Laid-Open No. 7-252609, Japanese Patent Application Laid-Open No. 5-239504, etc.). But,
These techniques apply powder metallurgy,
There is a problem that the cost becomes high due to the complexity of the process.
【０００６】一方、前記粉末冶金法よりも安価な製造方
法である溶製法によって高剛性鋼を製造する方法も提案
されている。例えば、特開平４−３２５６４１号公報に
は、高剛性の化合物粉末を熱間ダイス鋼や高速度工具鋼
の溶湯に分散させて鋳造する方法を開示している。ま
た、金型や工具の耐摩耗性を改善するために、ＶＣやＮ
ｂＣを１４ｖｏｌ％まで分散させた鋼も報告されている
（ＰＡ．ＢＬＡＣＫＭＯＲＥら：”Ｓｏ１ｉｄｉｆｉｃ
ａｔｉｏｎ ａｎｄ ｃａｓｔｉｎｇ ｏｆ ｍｅｔａ
１ｓ”Ｔｈｅ Ｍｅｔａ１ｓ Ｓｏｃｉｅｔｙ，Ｌｏｎ
ｄｏｎ，１９７７年；Ｐ５３３．Ｐ５３８）。[0006] On the other hand, there has been proposed a method of manufacturing high-rigidity steel by a melting method which is a cheaper manufacturing method than the powder metallurgy method. For example, Japanese Patent Laid-Open No. 4-325641 discloses a method of dispersing high-rigidity compound powder in a melt of hot die steel or high-speed tool steel and casting it. In addition, in order to improve the wear resistance of molds and tools, VC and N
A steel in which bC is dispersed up to 14 vol% has also been reported (PA. BLACKMORE et al .: “So1idific”).
ation and casting of meta
1s "The Meta 1s Society, Lon
don, 1977; P533. P538).
【０００７】特開平１０−６８０４０号公報には、高剛
性を有する化合物（４ａ、５ａ族の炭化物、ホウ化物、
またはその複合化物）を溶湯中での反応により生成・分
散させる方法が提示されている。この方法によると、安
価な溶製法により高剛性および高靭性を有する鋼材の製
造が可能になる。Japanese Unexamined Patent Publication No. 10-68040 discloses a compound having high rigidity (carbides of groups 4a and 5a, borides,
Alternatively, a method of producing / dispersing a complex compound thereof by a reaction in a molten metal is proposed. According to this method, it is possible to manufacture a steel material having high rigidity and high toughness by an inexpensive melting method.
【０００８】以上の様な溶製法による高剛性化技術で、
高剛性鋼を得る方法はある程度明確になった。しかし、
ほとんどの機械部品は剛性だけでなく強度、特に疲労強
度との両立が不可欠であるため、それらの小型軽量化に
は不十分であることが多い。殊に、上記の開示技術で
は、強度、特に疲労強度を向上させるための手法が明ら
かにされておらず、要求特性を満足させることが出来な
い。With the technique of high rigidity by the melting method as described above,
The method of obtaining high-strength steel has been clarified to some extent. But,
Since most mechanical parts are required to have not only rigidity but also strength, particularly fatigue strength, it is often insufficient to reduce their size and weight. In particular, in the above disclosed technology, a method for improving strength, particularly fatigue strength, has not been clarified, and required characteristics cannot be satisfied.
【０００９】剛性と強度の両立を図ることを目的とし
て、Ｖを多量に添加した鋼にＶＣとして化合物を形成す
る以上の炭素量を添加し、炭素を固溶させて焼入れる方
法が報告されている（特開２００１−７３０６８号公
報、ＣＡＭＰ−ＩＳＩＪ，Ｖｏｌ．１３（２０００）
ｐ．５４１−５４２．）。しかし、本方法においては、
焼入れることで剛性が低下するので、達成可能な剛性に
は自ずと限界があり、また、硬さにおいても、得られて
いる最高の硬さはＨＶ約３４０程度に止まる。さらに、
Ｃをあらかじめ多量に添加するので、粗大な初晶炭化物
が生成し、加工性や延靭性に問題が生じる。[0009] For the purpose of achieving both rigidity and strength, a method has been reported in which a steel containing a large amount of V is added with an amount of carbon in excess of that which forms a compound as VC, and the carbon is solid-solved and quenched. (Japanese Patent Laid-Open No. 2001-73068, CAMP-ISIJ, Vol. 13 (2000))
p. 541-542. ). However, in this method,
Since quenching reduces the rigidity, there is a limit to the achievable rigidity, and the maximum hardness that can be achieved is about 340 HV. further,
Since a large amount of C is added in advance, coarse primary crystal carbides are generated, which causes problems in workability and ductility.
【００１０】[0010]
【発明が解決しようとする課題】本発明はこうした状況
に着目してなされたものであって、その目的は、比較的
安価な溶製法により、鋼の加工性や延靱性を阻害するこ
となく、剛性の大幅な向上と共に、強度、特に疲労強度
とを兼ね備えた高疲労強度・高剛性鋼とその製造方法を
提供することにある。SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and its purpose is to prevent the workability and ductility of steel from being hindered by a relatively inexpensive melting method. It is an object of the present invention to provide a high fatigue strength / high rigidity steel having not only a great improvement in rigidity but also strength, particularly fatigue strength, and a manufacturing method thereof.
【００１１】[0011]
【課題を解決するための手段】本発明の高疲労強度・高
剛性鋼は、鉄または鉄合金からなるマトリックス中に、
ヤング率が３００ＧＰａ以上の化合物が溶製段階で５〜
５０ｖｏｌ％分散されてなる高剛性鋼において、表面か
ら１００μｍ深さ位置のビッカース硬さが６００以上で
あり、表面から１ｍｍ以上の深さ位置のビッカース硬さ
が４５０未満であるところに要旨を有する。The high-fatigue strength / high-rigidity steel of the present invention comprises a matrix made of iron or an iron alloy,
A compound having a Young's modulus of 300 GPa or more is 5 at the melting stage.
A high-rigidity steel in which 50 vol% is dispersed has a gist that the Vickers hardness at a depth of 100 μm from the surface is 600 or more and the Vickers hardness at a depth of 1 mm or more from the surface is less than 450.
【００１２】このように、高ヤング率を有する化合物お
よび上記特性を有する鋼は、高い剛性を有すると共に疲
労強度にも優れている。As described above, the compound having a high Young's modulus and the steel having the above properties have high rigidity and excellent fatigue strength.
【００１３】前記化合物としては、４ａおよび５ａ族元
素から選択される少なくとも１種の元素の炭化物、窒化
物、ホウ化物およびそれらの複合化物の１種以上である
ことが好ましい。特に、剛性の向上を図るには、前記化
合物がＴｉＢ2であることが好ましく、この場合、該高
疲労強度・高剛性鋼中に含有されるＴｉとＢの比（Ｔｉ
／Ｂ）は質量比で２．１以上、５以下であることが好ま
しい。The compound is preferably one or more of carbides, nitrides, borides and their composites of at least one element selected from 4a and 5a group elements. In particular, in order to improve the rigidity, the compound is preferably TiB 2 , and in this case, the ratio of Ti and B contained in the high fatigue strength / high rigidity steel (Ti
The mass ratio of / B) is preferably 2.1 or more and 5 or less.
【００１４】また、本発明に係る高疲労強度・高剛性鋼
においては、その表面から１００μｍの深さ位置におけ
る、下記式によって求められるＳＣ値およびＳＮ値の少
なくとも一方が０．４％以上であると共に、表面から１
ｍｍ以上の深さ位置における同ＳＣ値およびＳＮ値がい
ずれも０．４％未満であることが好ましい。ここでＳＣ
値およびＳＮ値は以下の式で計算され、該鋼中で他の成
分と結合せずに存在する炭素および窒素の量を示す。Further, in the high fatigue strength / high rigidity steel according to the present invention, at least one of the SC value and the SN value obtained by the following equation is 0.4% or more at a depth position of 100 μm from the surface. Along with 1 from the surface
It is preferable that both the SC value and the SN value at a depth position of mm or more are less than 0.4%. SC here
The value and the SN value are calculated by the following formulas and indicate the amounts of carbon and nitrogen present in the steel without being combined with other components.
【００１５】ＳＣ＝全Ｃ−（0.25・Ｔｉ−0.53・Ｂ＋0.24
・Ｖ＋0.13・Ｚｒ＋0.13・Ｎｂ＋0.065・Ｗ）
ＳＮ＝全Ｎ−（0.29・Ｔｉ−0.61・Ｂ＋0.28・Ｖ＋0.15・Ｚ
ｒ＋0.15・Ｎｂ＋0.076・Ｗ）
なお、全Ｃ量と全Ｎ量は表面から１００μｍ或いは１ｍ
ｍ以上の深さ位置での実測値を示すが、その他の元素量
はマトリックス中での平均値を表わす。SC = all C- (0.25.Ti-0.53.B + 0.24
・ V + 0.13 ・ Zr + 0.13 ・ Nb + 0.065 ・ W) SN = All N- (0.29 ・ Ti-0.61 ・ B + 0.28 ・ V + 0.15 ・ Z
r + 0.15 ・ Nb + 0.076 ・ W) The total amount of C and the total amount of N are 100 μm or 1 m from the surface.
The measured values at depths of m or more are shown, but the amounts of other elements represent average values in the matrix.
【００１６】さらに、該高疲労強度・高剛性鋼中に含ま
れるＣｒ量を２３％以下に制限することは該鋼の熱処理
特性を高める上で好ましい実施態様として推奨される。Further, limiting the amount of Cr contained in the high fatigue strength / high rigidity steel to 23% or less is recommended as a preferred embodiment for enhancing the heat treatment characteristics of the steel.
【００１７】また、本発明に係る製法は、上記特性を備
えた高疲労強度・高剛性鋼を製造する方法として位置付
けられるもので、その構成は、鉄または鉄合金からなる
マトリックス中にヤング率が３００ＧＰａ以上の化合物
を溶製段階で５〜５０ｖｏｌ％分散させた鋼材に、浸炭
焼入れ、窒化焼入れ、浸炭窒化焼入れのいずれかの熱処
理を施すところに要旨を有している。この方法を実施す
るに当たっては、熱処理に付される鋼材としてＣ含有量
が質量％で０．１％を超え、［０．２５（Ｔｉ−２．１
８Ｂ）＋０．１８］％未満の鋼材を使用することが推奨
される。Further, the manufacturing method according to the present invention is positioned as a method for manufacturing a high fatigue strength / high rigidity steel having the above-mentioned characteristics. Its constitution is that the Young's modulus is in a matrix made of iron or an iron alloy. The gist is that a steel material in which a compound of 300 GPa or more is dispersed in an amount of 5 to 50 vol% at a melting stage is subjected to any one of heat treatment of carburizing and quenching, nitriding and quenching, and carbonitriding and quenching. In carrying out this method, the C content of the steel material subjected to heat treatment exceeds 0.1% by mass%, and [0.25 (Ti-2.1
It is recommended to use less than 8B) +0.18]% steel.
【００１８】[0018]
【発明の実施形態】本発明者等は、剛性および強度、特
に疲労強度に優れた高疲労強度・高剛性鋼を提供するべ
く、様々な角度から検討した。その結果、高ヤング率を
有する化合物を分散した高剛性鋼に浸炭、窒化または浸
炭窒化などの熱処理を施し、熱処理前の内部硬度を保っ
たまま表面硬度のみを向上させることで、剛性、靭性お
よび延性を阻害することなく、全体としての強度、特に
疲労強度を向上させることが可能であることを見出し、
本発明を完成した。BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have studied from various angles in order to provide a high fatigue strength / high rigidity steel excellent in rigidity and strength, particularly fatigue strength. As a result, by performing heat treatment such as carburizing, nitriding or carbonitriding on high-rigidity steel in which a compound having a high Young's modulus is dispersed, and improving only the surface hardness while maintaining the internal hardness before the heat treatment, rigidity, toughness and It was found that it is possible to improve the strength as a whole, especially the fatigue strength, without impairing the ductility,
The present invention has been completed.
【００１９】本発明の高疲労強度・高剛性鋼は、鉄また
は鉄合金からなるマトリックス中にヤング率が３００Ｇ
Ｐａ以上の化合物を５〜５０ｖｏｌ％分散させて溶製さ
れたものである。このようにして得られた鋼（鉄または
鉄合金：以下、特に断らない限り「鋼」を用いる）は、
鋼自体の剛性が高く、そのヤング率は２２０〜３５０Ｇ
Ｐａである。しかし、鋼マトリックス中の前記化合物の
分散量が５ｖｏｌ％未満では、ヤング率が２２０ＧＰａ
以上の高剛性鋼を得ることができない。ヤング率が２２
０ＧＰａ以上の高剛性鋼を得るためには、５ｖｏｌ％以
上の前記化合物を鋼マトリックス中に分散させることが
必要である。さらにヤング率を高めるためには１５ｖｏ
ｌ％以上、より一層ヤング率を高めるには２０ｖｏｌ％
以上の前記化合物を鋼マトリックス中に分散させること
が望ましい。一方、前記化合物の鋼マトリックス中の分
散量が５０ｖｏｌ％を超えると、溶製後の鋼中に前記化
合物の凝集体等が生成して、靭性が低下し、構造部材と
しての使用が困難となる。また、靭性と機械加工性の観
点から、前記化合物量は４０ｖｏｌ％以下にすることが
好ましい。The high fatigue strength / high rigidity steel of the present invention has a Young's modulus of 300 G in a matrix made of iron or an iron alloy.
It is prepared by dispersing 5 to 50 vol% of a compound of Pa or more. The steel thus obtained (iron or iron alloy: hereinafter, "steel" is used unless otherwise specified) is
Steel itself has high rigidity and its Young's modulus is 220-350G
Pa. However, when the dispersion amount of the compound in the steel matrix is less than 5 vol%, the Young's modulus is 220 GPa.
The above high rigidity steel cannot be obtained. Young's modulus is 22
In order to obtain a high-rigidity steel of 0 GPa or more, it is necessary to disperse 5 vol% or more of the above compound in the steel matrix. 15vo to further increase Young's modulus
1% or more, 20 vol% to further increase Young's modulus
It is desirable to disperse the above compounds in the steel matrix. On the other hand, when the amount of the compound dispersed in the steel matrix exceeds 50 vol%, aggregates of the compound are formed in the steel after melting, the toughness is lowered, and it becomes difficult to use it as a structural member. . From the viewpoint of toughness and machinability, the amount of the compound is preferably 40 vol% or less.
【００２０】本発明に係る高剛性鋼は、その表面から１
００μｍ深さ位置でのビッカース硬さが６００以上であ
ると共に、表面から１ｍｍ以上の深さ位置でのビッカー
ス硬さが４５０未満でなければならない。The high-rigidity steel according to the present invention has a surface 1
The Vickers hardness at a depth of 00 μm must be 600 or more, and the Vickers hardness at a depth of 1 mm or more from the surface must be less than 450.
【００２１】高剛性鋼の表面から１００μｍ深さ位置で
のビッカース硬さが６００未満では、充分な表面硬度が
得られず、高剛性鋼に強度、特に疲労強度を付加するこ
とが不可能となる。好ましいビッカース硬さは６５０以
上、さらに好ましくは７００以上である。If the Vickers hardness at a depth of 100 μm from the surface of the high-rigidity steel is less than 600, sufficient surface hardness cannot be obtained, and it becomes impossible to add strength, particularly fatigue strength, to the high-rigidity steel. . The Vickers hardness is preferably 650 or more, more preferably 700 or more.
【００２２】また、表面から１ｍｍ以上の深さ位置での
ビッカース硬さが４５０以上になると、高剛性鋼の内部
まで硬度が高まってしまい、硬さの割に疲労強度が向上
せず、また靭性や加工性が劣化する。好ましいビッカー
ス硬さの上限は４３０未満であり、さらに好ましくは４
１０未満である。このような性質を有する高剛性鋼を得
るには、溶製後に、後述する熱処理を施せばよい。If the Vickers hardness at a depth of 1 mm or more from the surface is 450 or more, the hardness increases to the inside of the high-rigidity steel, the fatigue strength does not improve relative to the hardness, and the toughness does not increase. And workability deteriorate. The upper limit of the preferable Vickers hardness is less than 430, and more preferably 4
It is less than 10. In order to obtain a high-rigidity steel having such properties, the heat treatment described below may be performed after the melting.
【００２３】尚、本発明に係る鋼表面および内部組織
は、後述するＣ量、Ｎ量だけでなく、焼入れ時に生成す
るマルテンサイト量など複雑な組織状態が関係するもの
である。特に、表面層に関する組織は観察・定量化が難
しく評価が困難であるため、本発明においては、該鋼の
表面から１００μmおよび１ｍｍ以上の深さ位置におけ
るビッカース硬さによって表面組織および内部組織の評
価を行った。The steel surface and internal structure according to the present invention are related not only to the C content and N content described later, but also to a complicated microstructure state such as the amount of martensite produced during quenching. In particular, since it is difficult to observe and quantify the structure of the surface layer and difficult to evaluate, in the present invention, the surface structure and the internal structure are evaluated by the Vickers hardness at a depth of 100 μm and 1 mm or more from the surface of the steel. I went.
【００２４】本発明に用いる鉄合金には、通常の構造部
材として用いられる炭素鋼、低合金鋼を用いることがで
きる。例えば、機械構造用炭素鋼（例えば、Ｓ−Ｃ材な
ど）、ニッケルクロム鋼（例えば、ＳＮＣ材など）、ニ
ッケルモリブデン鋼（例えば、ＳＮＣＭ材など）、クロ
ム鋼（例えば、ＳＣｒ材など）、クロムモリブデン鋼
（例えば、ＳＣＭ材など）、マンガン鋼（例えば、ＳＭ
ｎ材など）、マンガンクロム鋼（例えば、ＳＭｎＣ材な
ど）、バネ鋼（例えば、ＳＵＰ材など）、高炭素クロム
鋼（例えば、ＳＵＪ材など）などが挙げられる。本発明
の高剛性高靭性鋼のマトリックス成分として、これらの
炭素鋼や、低合金鋼を用いることで、これら鉄合金が持
つ特性に、高い剛性を付加することができる。As the iron alloy used in the present invention, carbon steel and low alloy steel which are commonly used as structural members can be used. For example, carbon steel for machine structure (for example, SC material), nickel chrome steel (for example, SNC material), nickel molybdenum steel (for example, SNCM material), chrome steel (for example, SCr material), chrome Molybdenum steel (eg SCM material), manganese steel (eg SM
n material), manganese chrome steel (for example, SMnC material), spring steel (for example, SUP material), high carbon chrome steel (for example, SUJ material), and the like. By using these carbon steels and low alloy steels as the matrix component of the high-rigidity and high-toughness steel of the present invention, high rigidity can be added to the properties of these iron alloys.
【００２５】また、本発明に係る高疲労強度・高剛性鋼
を製造するに際して、その溶製法としては、真空溶解
法、プラズマ溶解法、コールドクルーシブル溶解法、マ
ーク溶解法等が挙げられる。Further, when manufacturing the high fatigue strength / high rigidity steel according to the present invention, as the melting method, there are a vacuum melting method, a plasma melting method, a cold crucible melting method, a mark melting method and the like.
【００２６】本発明に係る高剛性鋼中に含まれるヤング
率３００ＧＰａ以上の化合物は、４ａ、５ａ族元素の炭
化物、窒化物、ホウ化物またはその複合化物であること
が好ましい。このような化合物には、高いヤング率を有
するものが多く（表１参照）、これらの中でも特に高い
ヤング率を有するＶＣ、ＴｉＣ、ＴｉＢ2、ＮｂＢ2等、
またはそれらの複合化物を用いることによりさらに高い
靭性、剛性を有する高剛性鋼を得ることができる。The compound having a Young's modulus of 300 GPa or more contained in the high-rigidity steel according to the present invention is preferably a carbide, nitride, boride of a group 4a or 5a element, or a compound thereof. Many of these compounds have a high Young's modulus (see Table 1), and among these, VC, TiC, TiB 2 , NbB 2, etc., which have a particularly high Young's modulus,
Alternatively, a high-rigidity steel having higher toughness and rigidity can be obtained by using a compound thereof.
【００２７】[0027]
【表１】 [Table 1]
【００２８】本発明に係る高疲労強度・高剛性鋼が高疲
労強度と高剛性の両立をし得たのは、前述した高いヤン
グ率を有する化合物を該高剛性鋼中に分散することに加
えて、該高剛性鋼の表面硬度のみを向上させたことによ
る。The high fatigue strength / high rigidity steel according to the present invention was able to achieve both high fatigue strength and high rigidity in addition to the above-mentioned compound having a high Young's modulus being dispersed in the high rigidity steel. And the surface hardness of the high-rigidity steel is improved.
【００２９】この表面の硬度のみの向上は、本発明に係
る高疲労強度・高剛性鋼を製造するにあたり、上述した
高ヤング率の化合物を鋼中に５〜５０ｖｏｌ％分散させ
た鋼材に、浸炭焼入れ、窒化焼入れ、浸炭窒化焼入れの
いずれかの熱処理を施すことで、表層部に固溶炭素や固
溶窒素を生成させることによって成し得たのである。In order to produce the high fatigue strength and high rigidity steel according to the present invention, the improvement of only the hardness of the surface is carburized on a steel material in which the above-mentioned compound of high Young's modulus is dispersed in the steel in an amount of 5 to 50% by volume. This can be achieved by generating solid solution carbon or solid solution nitrogen in the surface layer portion by performing any heat treatment of quenching, nitriding quenching, and carbonitriding quenching.
【００３０】溶製後の鋼に上記熱処理を施すことで、表
層部に熱処理由来の固溶（Ｃ＋Ｎ）を生成させることが
できる。これらの固溶（Ｃ＋Ｎ）の存在によって、焼入
れ後、鋼の表層にマルテンサイト組織が生成し、強度、
特に疲労強度が向上する。また、溶製時に多量のＣを添
加する必要がなくなるので、大型初晶の生成が抑制さ
れ、加工性の低下も抑えられる。さらに、被削性や靱性
も比較的良好である。また、炭化物（窒化物）生成元素
が合金成分として添加されている場合には、浸炭あるい
は窒化等の熱処理により表層に炭化物や窒化物が生成
し、さらに剛性が向上する。特に浸炭は窒化やホウ化処
理と比較すると深く入るので、強度向上に効果的であ
る。By subjecting the steel after smelting to the above heat treatment, a solid solution (C + N) derived from the heat treatment can be generated in the surface layer portion. Due to the presence of these solid solutions (C + N), a martensite structure is generated in the surface layer of the steel after quenching, and the strength,
In particular, fatigue strength is improved. Further, since it is not necessary to add a large amount of C at the time of melting, the generation of large primary crystals is suppressed and the deterioration of workability is also suppressed. Further, machinability and toughness are also relatively good. Further, when a carbide (nitride) -forming element is added as an alloy component, heat treatment such as carburizing or nitriding produces carbide or nitride in the surface layer, further improving rigidity. In particular, carburization is deeper than nitriding or boration, so it is effective in improving strength.
【００３１】しかし、上述の熱処理によって焼きが入る
のは表層のみで、内部の組織は焼入れ前の特性を保持し
ており、マルテンサイト相生成による鋼全体の剛性の低
下は少ないため、剛性と共に疲労強度にも優れた高疲労
強度・高剛性鋼を得ることができる。However, the above heat treatment quenches only the surface layer, the internal structure retains the characteristics before quenching, and the decrease in the rigidity of the entire steel due to the formation of martensite phase is small. It is possible to obtain high fatigue strength and high rigidity steel with excellent strength.
【００３２】上記熱処理によって鋼の強度向上効果を得
るには、鋼の表層より１００μｍ深さにおける固溶Ｃ、
あるいは固溶Ｎ量の少なくとも一方が０．４％以上でな
ければならない。なお、固溶Ｃ（ＳＣ）および固溶Ｎ
（ＳＮ）量は以下の式で与えられる。
ＳＣ＝全Ｃ−（0.25・Ｔｉ−0.53・Ｂ＋0.24・Ｖ＋0.13・Ｚ
ｒ＋0.13・Ｎｂ＋0.065・Ｗ）
ＳＮ＝全Ｎ−（0.29・Ｔｉ−0.61・Ｂ＋0.28・Ｖ＋0.15・Ｚ
ｒ＋0.15・Ｎｂ＋0.076・Ｗ）In order to obtain the effect of improving the strength of steel by the above heat treatment, solid solution C at a depth of 100 μm from the surface layer of steel,
Alternatively, at least one of the dissolved N amounts must be 0.4% or more. Note that solid solution C (SC) and solid solution N
The (SN) amount is given by the following formula. SC = All C- (0.25 / Ti-0.53 / B + 0.24 / V + 0.13 / Z
r + 0.13 ・ Nb + 0.065 ・ W) SN = All N- (0.29 ・ Ti-0.61 ・ B + 0.28 ・ V + 0.15 ・ Z
r + 0.15 / Nb + 0.076 / W)
【００３３】式中のＴｉ、Ｖ、Ｚｒ、Ｎｂ、Ｗは強力な
炭窒化物生成元素であるため、全Ｃ量および全Ｎ量か
ら、これらの元素と化合するＣ、Ｎ量を差し引く必要が
有る。また、鋼中のＢは、Ｔｉと結合して、ＴｉＢ2と
なり、Ｃ、Ｎと化合するＴｉ量を減少させるので、上記
式ではＢ含有量を付加している。なお、全Ｃ量と全Ｎ量
の値は熱処理後の表層から１００μｍでの実測値を示す
が、その他の元素量はマトリックス中の平均値を表わし
ている。Since Ti, V, Zr, Nb, and W in the formula are strong carbonitride-forming elements, it is necessary to subtract the C and N contents combined with these elements from the total C and total N contents. There is. Further, B in the steel is combined with Ti to form TiB 2 , which reduces the amount of Ti combined with C and N, so the B content is added in the above formula. The values of the total C content and the total N content are the measured values at 100 μm from the surface layer after the heat treatment, while the other element contents are the average values in the matrix.
【００３４】また、表面から１ｍｍ以上の深さ位置での
ＳＣ値、ＳＮ値はいずれも０．４％未満でなければなら
ない。上記ＳＣ値およびＳＮ値が０．４を超えると、鋼
の内部まで硬度が高まり、硬さの割に疲労強度が向上せ
ず、また靭性や、加工性が低下するからである。なお、
このときの全Ｃおよび全Ｎの値は熱処理後の表層から１
ｍｍでの実測値を示す。Both the SC value and the SN value at a depth of 1 mm or more from the surface must be less than 0.4%. When the SC value and the SN value exceed 0.4, the hardness is increased to the inside of the steel, the fatigue strength is not improved relative to the hardness, and the toughness and workability are deteriorated. In addition,
The values of total C and total N at this time are 1 from the surface layer after heat treatment.
The measured value in mm is shown.
【００３５】前述した、浸炭焼入れ、窒化焼入れおよび
浸炭窒化焼入れによる効果は、高ヤング率を有する化合
物がＴｉＢ2である場合に特に効果的である。即ち、Ｔ
ｉＢ2の剛性は特に高く、得られる鋼の剛性を向上させ
るのに最も効果的である（ＴｉＢ2：５２９ＧＰａ、Ｔ
ｉＣ：４５１ＧＰａ、ＶＣ：４２１ＧＰａ）。しかし、
この場合、マトリックス中にＣを多量に添加すると、Ｃ
はＴｉと結合して、ＴｉＣを生成する。その結果、Ｂが
余剰成分として残り、この余剰Ｂは鉄ホウ化物（Ｆｅ2
Ｂ）を生成する。このＦｅＢ2とＦｅの共晶温度は熱間
加工される温度域に存在するため、熱間加工性を極端に
低下させる。そのため、従来の知見では、高剛性が得ら
れるＴｉＢ2系での剛性と強度の両立は難しいと考えら
れていた。The above-mentioned effects of the carburizing and quenching, the nitriding and the carbonitriding and quenching are particularly effective when the compound having a high Young's modulus is TiB 2 . That is, T
iB 2 has a particularly high rigidity and is most effective in improving the rigidity of the obtained steel (TiB 2 : 529 GPa, T
iC: 451 GPa, VC: 421 GPa). But,
In this case, if a large amount of C is added to the matrix, C
Combines with Ti to form TiC. As a result, B remains as a surplus component, and this surplus B is iron boride (Fe 2
B) is generated. Since the eutectic temperature of FeB 2 and Fe exists in the hot working temperature range, the hot workability is extremely lowered. Therefore, according to the conventional knowledge, it has been considered that it is difficult to achieve both high rigidity and high strength in the TiB 2 system that can obtain high rigidity.
【００３６】しかし、本発明者等は、前記高剛性鋼中に
含まれるＴｉとＢの比（Ｔｉ／Ｂ）が質量比で２．１以
上、５以下であり、ＴｉＢ2系でも目的とする強度と剛
性を兼ね備えた鋼が得られることを見出した。However, the inventors of the present invention have a Ti / B ratio (Ti / B) contained in the high-rigidity steel of 2.1 or more and 5 or less in mass ratio, and the TiB 2 system is also intended. It has been found that a steel having both strength and rigidity can be obtained.
【００３７】Ｔｉ／Ｂの値が２．１未満であると、鋼中
にＴｉＢ2として結合しない余剰Ｂが生じる。上述した
ように、余剰Ｂは鋼マトリックス中のＦｅと結合してＦ
ｅＢ 2を生成し、得られる鋼の熱間加工性を極端に低下
させる。また、Ｔｉ／Ｂの値が５を超すと、マトリック
ス中に多量のＴｉが存在することとなり、このようにＴ
ｉが多量に固溶されている場合、上述したようにＴｉＣ
を形成するため、浸炭や窒化が抑制される。ゆえに、前
記高剛性鋼中に含まれるＴｉとＢの比（Ｔｉ／Ｂ）は質
量比で２．１以上、５以下であることが好ましい。If the value of Ti / B is less than 2.1, in the steel
To TiB2A surplus B that does not combine as Mentioned above
As described above, the excess B combines with Fe in the steel matrix to form F
eB 2Of steel and the hot workability of the resulting steel is extremely reduced.
Let Also, if the value of Ti / B exceeds 5, the matrix
A large amount of Ti is present in the alloy, and T
When i is dissolved in a large amount, as described above, TiC
Therefore, carburization and nitriding are suppressed. Therefore, before
The ratio of Ti and B contained in the high rigidity steel (Ti / B) is
The amount ratio is preferably 2.1 or more and 5 or less.
【００３８】また、該高疲労強度・高剛性鋼に含まれる
Ｃｒ量を２０％以下に抑えることも有効となる。即ち、
Ｃｒはマトリックスに固溶して剛性を向上させる働きが
あるため、必要な成分であるが、反面、Ｃｒはフェライ
トフォーマーであり、その含有量が２０％を超えると低
合金鋼や炭素鋼ではオーステナイト温度域でもほとんど
がフェライト相になるため、焼入れ焼戻し処理によるマ
ルテンサイト組織の現出が著しく害される。さらにマト
リックス中のＣｒ含有量が増加すると、溶製後、鋼の表
層に緻密なＣｒの酸化物層が生成し、浸炭、浸窒処理が
困難になる。より好ましいＣｒの添加量の上限は１３％
であり、好ましいＣｒ添加量の下限は０．５％である。It is also effective to suppress the amount of Cr contained in the high fatigue strength / high rigidity steel to 20% or less. That is,
Cr is a necessary component because it acts as a solid solution in the matrix to improve the rigidity, but on the other hand, Cr is a ferrite former, and if its content exceeds 20%, it will be low alloy steel and carbon steel. Even in the austenite temperature range, most of it becomes a ferrite phase, so that the appearance of martensite structure due to quenching and tempering treatment is significantly impaired. When the Cr content in the matrix is further increased, a dense Cr oxide layer is formed on the surface layer of the steel after melting, which makes carburization and nitrification processes difficult. More preferable upper limit of Cr content is 13%
And the preferable lower limit of the Cr addition amount is 0.5%.
【００３９】上述した成分組成に加えて、マトリックス
中のＣ含有量は質量％で０．１％を超え、［０．２５
（Ｔｉ−２．１８Ｂ）＋０．１８］％未満であることが
好ましい。Ｃ含有量が０．１％以下では、浸炭、窒化な
どで表面硬度の向上に必要な表層のＣ（またはＮ）濃度
を得るための表面処理に長時間を要する。一方、Ｃ含有
量が［０．２５（Ｔｉ−２．１８Ｂ）＋０．１８］％以
上となると、鋼中に過剰なＣが存在することになり、過
剰なＣはＴｉＣを生成する。その結果、余剰のＢを生
じ、上述したようにＦｅＢ2が生成する。よって、Ｆｅ
Ｂ2の生成を抑えて、熱間加工性を確保するためには、
溶製後・熱処理前のＣ含有量を［０．２５（Ｔｉ−２．
１８Ｂ）＋０．１８］％未満に抑えることが望ましい。In addition to the above-mentioned component composition, the C content in the matrix is more than 0.1% by mass%, [0.25
It is preferably less than (Ti-2.18B) +0.18]%. When the C content is 0.1% or less, it takes a long time for the surface treatment to obtain the C (or N) concentration of the surface layer necessary for improving the surface hardness by carburizing, nitriding, or the like. On the other hand, when the C content is [0.25 (Ti-2.18B) +0.18]% or more, excess C is present in the steel, and the excess C forms TiC. As a result, surplus B is generated, and FeB 2 is generated as described above. Therefore, Fe
In order to suppress the formation of B 2 and ensure hot workability,
After the melting and before the heat treatment, the C content is [0.25 (Ti-2.
18B) +0.18]%.
【００４０】上記の元素以外に、焼入れ性向上を目的と
して、Ｃｕ：３．０％以下、Ｍｎ：２．０％以下、Ｍ
ｏ：２．０％以下、Ｗ：２．０％以下、Ｎｉ：３．０％
以下、Ｓｉ：３．０％以下を添加しても良い。しかし、
これらの選択元素を、上述した量以上添加しても効果は
飽和し、コストアップするだけであるので無駄である。In addition to the above elements, Cu: 3.0% or less, Mn: 2.0% or less, M for the purpose of improving hardenability.
o: 2.0% or less, W: 2.0% or less, Ni: 3.0%
Hereinafter, Si: 3.0% or less may be added. But,
Even if these selective elements are added in the above amounts, the effect is saturated and the cost is increased, which is wasteful.
【００４１】[0041]
【実施例】以下実施例によって本発明をさらに詳述する
が、下記実施例は本発明を制限するものではなく、本発
明の趣旨を逸脱しない範囲で変更実施することはすべて
本発明の技術範囲に包含される。なお、「％」は特に断
らない限り質量基準であり、各物性値は以下の方法で測
定した。The present invention will be described in more detail with reference to the following examples, but the following examples are not intended to limit the present invention, and all modifications within the scope of the present invention are within the technical scope of the present invention. Included in. In addition, "%" is based on mass unless otherwise specified, and each physical property value was measured by the following methods.
【００４２】［ヤング率］サンプルから引張試験片を加
工し、ＪＩＳ Ｚ ２２８０に基づいてヤング率の測定
を行った。[Young's modulus] A tensile test piece was processed from the sample, and the Young's modulus was measured based on JIS Z 2280.
【００４３】［疲労強度］サンプルから直径８ｍｍの丸
棒に加工し、平滑回転曲げ疲労試験によって、Ｎ＝１０
7回の疲労強度を評価した。７００ＭＰａ以上を合格と
する。[Fatigue Strength] A sample was processed into a round bar having a diameter of 8 mm and subjected to a smooth rotation bending fatigue test to obtain N = 10.
The fatigue strength was evaluated 7 times. Pass 700 MPa or more.
【００４４】［ビッカース硬さ］ＪＩＳ Ｚ ２２４４
に基づいて、試験片の１００μｍ深さ位置および１ｍｍ
深さ位置でのビッカース硬さを測定した。[Vickers hardness] JIS Z 2244
Based on 100 μm depth position and 1 mm of the test piece
The Vickers hardness at the depth position was measured.
【００４５】製造例
（１）真空溶解製造例１ サンプルＡ、Ｂ、Ｈ〜Ｑ
ヤング率３００ＧＰａ以上の化合物としてＴｉＢ2を使
用し、真空溶解法を採用したサンプルＡの製法について
説明する。Manufacturing Example (1) Vacuum Melting Manufacturing Example 1 Samples A, B, H to Q A method of manufacturing sample A using TiB 2 as a compound having a Young's modulus of 300 GPa or more and employing the vacuum melting method will be described.
【００４６】マトリックス成分として、クロム鋼（Ｃ
ｒ：１５．０質量％、Ｃ：０．２質量％、Ｎ：０．０１
質量％）を使用し、これを真空誘導炉に導入し、特開平
１０−６８０４８号に記載されている様に、化合物が完
全に溶解する温度（２２７３℃）で溶解しておき、表２
に示す組成となるように、Ｃ、Ｂ等を適宜添加した。次
に、溶解したサンプルを鋳型または水冷鋳型に注湯し
て、２０ｋｇの鋼塊を製造した。冷却は、真空中（真空
度：０．１３〜１．３Ｐａ）で行い、冷却・凝固の過程
でＴｉとＢを反応させることによりＴｉＢ2を生成、晶
出させ、ＴｉＢ2が分散した鋼を得た。このときの冷却
速度は、鋳型の場合は約１０Ｋ／分程度、水冷鋳型の場
合は４０Ｋ／分程度とした。その後、熱間鍛造により直
径２０ｍｍの丸棒に加工した後、各々の試験片に機械加
工した。As a matrix component, chromium steel (C
r: 15.0% by mass, C: 0.2% by mass, N: 0.01
Mass%), which was introduced into a vacuum induction furnace and melted at a temperature (2273 ° C.) at which the compound was completely dissolved, as described in JP-A-10-68048.
C, B, etc. were appropriately added so that the composition shown in FIG. Next, the melted sample was poured into a mold or a water-cooled mold to produce a 20 kg steel ingot. Cooling is performed in a vacuum (vacuum degree: 0.13 to 1.3 Pa), TiB 2 is generated and crystallized by reacting Ti and B in the process of cooling and solidification, and a steel in which TiB 2 is dispersed is produced. Obtained. The cooling rate at this time was about 10 K / min for the mold and about 40 K / min for the water-cooled mold. Then, after hot working into a round bar having a diameter of 20 mm, each test piece was machined.
【００４７】高ヤング率を有する化合物としてＴｉＢ2
を使用したサンプルＢ、Ｈ〜Ｑも上述した方法と同様に
して作成した。尚、サンプルＩ、Ｊ、Ｋ、Ｌは、熱間鍛
造時に割れが発生し、その後の処理が出来なかった。TiB 2 as a compound having a high Young's modulus
Samples B and H to Q using the same were prepared in the same manner as the above-mentioned method. Note that Samples I, J, K, and L were not able to be subjected to subsequent treatment because cracking occurred during hot forging.
【００４８】製造例２ サンプルＣ〜ＥおよびＧ
高ヤング率を有する化合物がＶＣであるサンプルＣ〜Ｅ
も、高ヤング率を有する化合物がＴｉＢ2の場合と同様
にして、表３に示した成分を真空誘導炉中２２７３Ｋで
溶解してから鋳型に鋳込み、冷却・凝固の過程でＶとＣ
とを反応させることによりＶＣが分散した鋼を製造し
た。その後、上述した方法により、各々の試験片に機械
加工した。 Production Example 2 Samples C to E and G Samples C to E in which the compound having a high Young's modulus is VC
In the same manner as in the case where the compound having a high Young's modulus is TiB 2 , the components shown in Table 3 are melted at 2273 K in a vacuum induction furnace and then cast into a mold, and V and C are added in the process of cooling and solidification.
A steel with dispersed VC was produced by reacting with. Then, each test piece was machined by the method described above.
【００４９】製造例３ サンプルＦ
高ヤング率を有する化合物がＴｉＣであるサンプルＦ
も、高ヤング率を有する化合物がＴｉＢ2の場合と同様
にして、表３に示した成分を真空誘導炉中２２７３Ｋで
溶解してから鋳型に鋳込み、冷却・凝固の過程でＴｉと
Ｃとを反応させることによりＴｉＣが分散した鋼を製造
した。その後、上述した方法により、各々の試験片に機
械加工した。 Production Example 3 Sample F Sample F in which the compound having a high Young's modulus is TiC
In the same manner as in the case where the compound having a high Young's modulus is TiB 2 , the components shown in Table 3 are melted in a vacuum induction furnace at 2273 K and then cast into a mold, and Ti and C are mixed in the process of cooling and solidification. A steel in which TiC was dispersed was produced by the reaction. Then, each test piece was machined by the method described above.
【００５０】[0050]
【表２】 [Table 2]
【００５１】（２）熱処理
前述した方法で得たサンプルに表３に示す熱処理を施し
た。尚、熱処理条件は下記の通りとした。実験で用いた
試験片のＣｒ濃度は高く、通常のガス浸炭では浸炭、浸
炭窒化を行うことが難しいため、真空浸炭を採用した。
さらに、浸炭および浸炭窒化処理では、表層炭素濃度お
よび窒素濃度と処理時間を変化させたそれぞれ２種類の
条件で行った。(2) Heat Treatment The samples obtained by the above-mentioned method were subjected to the heat treatment shown in Table 3. The heat treatment conditions were as follows. Since the Cr concentration of the test piece used in the experiment is high and it is difficult to carry out carburizing and carbonitriding with ordinary gas carburizing, vacuum carburizing was adopted.
Further, the carburizing and carbonitriding treatments were performed under two kinds of conditions, each of which varied the surface carbon concentration and nitrogen concentration and the treatment time.
【００５２】浸炭（１）は、真空炉中、試験片を９５０
℃に加熱し、これにプロパンを主体とした浸炭性ガスを
通じて６時間浸炭を行い、油焼入れを行った。その後、
２００℃で３０分間の焼き戻しを行った。このときの表
層炭素濃度は０．８質量％であった。For carburizing (1), the test piece was 950 in a vacuum furnace.
It was heated to 0 ° C., and carburizing gas containing propane as a main component was passed through this for carburizing for 6 hours to effect oil quenching. afterwards,
Tempering was performed at 200 ° C. for 30 minutes. The surface carbon concentration at this time was 0.8 mass%.
【００５３】浸炭（２）は、真空炉中、試験片を９００
℃に加熱し、これにプロパンを主体とした浸炭性ガスを
通じて２時間浸炭を行い、油焼入れを行った。その後、
２００℃で３０分間の焼き戻しを行った。このときの表
層炭素濃度は０．７質量％であった。For carburizing (2), 900 pieces of test pieces were placed in a vacuum furnace.
The mixture was heated to 0 ° C., and carburizing gas containing propane as a main component was passed through the mixture for carburizing for 2 hours to quench oil. afterwards,
Tempering was performed at 200 ° C. for 30 minutes. The surface carbon concentration at this time was 0.7 mass%.
【００５４】浸炭窒化（１）は、真空炉中、試験片を９
００℃に加熱し、６時間浸炭窒化を行った。この時、プ
ロパンを主体とした浸炭性ガスとアンモニア（窒化ガ
ス）を使用し、各々のガス添加量を調整して、ＣとＮの
表層濃度を制御した。その後、２００℃で３０分間の焼
き戻しを行った。このときの表層炭素濃度は０．６質量
％であり、表層窒素濃度は０．４５％であった。Carbonitriding (1) was carried out using a test piece in a vacuum furnace.
It heated at 00 degreeC and carbonitrided for 6 hours. At this time, a carburizing gas mainly composed of propane and ammonia (nitriding gas) were used, and the amount of each gas added was adjusted to control the surface concentration of C and N. Then, tempering was performed at 200 ° C. for 30 minutes. At this time, the surface carbon concentration was 0.6% by mass, and the surface nitrogen concentration was 0.45%.
【００５５】浸炭窒化（２）は、真空炉中、試験片を９
００℃に加熱し、４時間浸炭窒化を行った。この時、浸
炭窒化（１）と同様にして、ＣとＮの表層濃度を制御し
た。その後、２００℃で３０分間の焼き戻しを行った。
このときの表層炭素濃度は０．４質量％であり、表層窒
素濃度は０．２５％であった。For carbonitriding (2), the test piece was placed in a vacuum furnace.
It heated at 00 degreeC and carbonitrided for 4 hours. At this time, the surface layer concentrations of C and N were controlled in the same manner as carbonitriding (1). Then, tempering was performed at 200 ° C. for 30 minutes.
At this time, the surface carbon concentration was 0.4% by mass, and the surface nitrogen concentration was 0.25%.
【００５６】窒化には、イオン窒化処理を採用した。真
空容器中、グロー放電により試験片を５５０℃に加熱
し、これにアンモニアガスを流入して１０時間窒化を行
った。このときの表層窒素濃度は０．７％であった。Ion nitriding treatment was adopted for nitriding. The test piece was heated to 550 ° C. by glow discharge in a vacuum container, and ammonia gas was introduced into the test piece for nitriding for 10 hours. The surface nitrogen concentration at this time was 0.7%.
【００５７】焼入れ焼戻し処理は、高Ｃｒ鋼においても
オーステナイト化が予想される１０００℃に試験片を加
熱・油焼入れ後、２００℃で３０分間の焼戻しを行っ
た。In the quenching and tempering treatment, the test piece was heated to 1000 ° C., where austenitization is expected even in high Cr steel, and oil-quenched, and then tempered at 200 ° C. for 30 minutes.
【００５８】時効処理は、５５０℃で２時間行った。The aging treatment was performed at 550 ° C. for 2 hours.
【００５９】尚、表３中、有効硬化層深さとは、それぞ
れの熱処理によって達成される硬化層の深さを示してい
る。In Table 3, the effective hardened layer depth indicates the depth of the hardened layer achieved by each heat treatment.
【００６０】[0060]
【表３】 [Table 3]
【００６１】表４には、それぞれのサンプルに施した熱
処理方法と各種熱処理後の表層から１００μｍ深さ位置
及び１ｍｍ深さ位置におけるビッカース硬さ、ＣとＮ濃
度および固溶Ｃと固溶Ｎ濃度を示している。Table 4 shows the heat treatment method applied to each sample and the Vickers hardness, C and N concentration, and solid solution C and solid solution N concentration at the depths of 100 μm and 1 mm from the surface layer after various heat treatments. Is shown.
【００６２】[0062]
【表４】 [Table 4]
【００６３】[0063]
【表５】 [Table 5]
【００６４】表４に表３の各熱処理後のヤング率と疲労
強度の測定結果を示している。Table 4 shows the measurement results of Young's modulus and fatigue strength after each heat treatment in Table 3.
【００６５】熱処理による表面硬化を行わなかった実験
Ｎｏ．１〜３では、表面の固溶Ｃおよび固溶Ｎ量が低く
十分な表面硬度が得られないため、疲労強度も低い。ま
た、実験Ｎｏ．４〜６、８、９は、熱処理時に浸炭、窒
化などの硬化処理を行っていないため表面硬度が低く、
疲労強度も低い。実験Ｎｏ．７（サンプルＤ）は溶製前
の炭素添加量が多く、焼入れ焼戻し処理により、内部ま
でマルテンサイト組織となって硬化しているため、加工
性、靱性が悪い。Ｎｏ．１２は、浸炭（２）の表層炭素
濃度が十分でないため、十分な浸炭特性が得られていな
い。実験Ｎｏ．１７は、ＴｉＢ2量が少ないため、十分
なヤング率が得られていない。Experiment No. in which the surface was not hardened by heat treatment In Nos. 1 to 3, since the amounts of solid solution C and solid solution N on the surface are low and sufficient surface hardness cannot be obtained, the fatigue strength is also low. In addition, the experiment No. Nos. 4 to 6, 8 and 9 have low surface hardness because they are not subjected to hardening treatment such as carburizing and nitriding during heat treatment,
Fatigue strength is also low. Experiment No. 7 (Sample D) had a large amount of carbon added before melting and was hardened into a martensite structure even in the interior by quenching and tempering treatment, so that the workability and toughness were poor. No. In No. 12, since the surface carbon concentration of carburizing (2) is not sufficient, sufficient carburizing characteristics are not obtained. Experiment No. Sample No. 17 has a small amount of TiB 2 and thus does not have a sufficient Young's modulus.
【００６６】サンプルＭを用いた実験Ｎｏ．２２は、Ｔ
ｉ／Ｂ値が高く、多量のＴｉが過剰として固溶し、Ｔｉ
Ｃを生成するため、浸炭が抑制され、十分な浸炭特性が
得られていない。実験Ｎｏ．２３は、サンプル中のＣｒ
含有量が多いため、浸炭時にもオーステナイト化せず、
十分な強度が得られない。実験Ｎｏ．２４で用いたサン
プルＯは母材の炭素含有量が少なく、浸炭に長時間を要
するので不経済であるだけでなく、心部強度が不十分
で、疲労試験においても内部破壊が生じ、十分な疲労強
度が得られていない。実験Ｎｏ．２５は、他のサンプル
に比べて炭窒化物生成元素の含有量が多く、サンプル中
の炭素のほとんどがそれらの元素と結合し、マルテンサ
イト生成のためのＣが確保されないため、十分な硬度が
得られなかったものと考えられる。実験Ｎｏ．２６は、
浸炭窒化（２）条件（表層炭素濃度および窒素濃度）が
十分でないため、強度不足となっている。Experiment No. using the sample M 22 is T
The i / B value is high, and a large amount of Ti dissolves in excess to form a solid solution.
Since C is generated, carburization is suppressed and sufficient carburizing characteristics are not obtained. Experiment No. 23 is Cr in the sample
Since the content is large, it does not become austenite during carburization,
Sufficient strength cannot be obtained. Experiment No. The sample O used in No. 24 is uneconomical because the carbon content of the base material is small and carburization requires a long time, and not only is uneconomical, but the core strength is insufficient and internal fracture occurs even in the fatigue test, Fatigue strength is not obtained. Experiment No. No. 25 has a higher content of carbonitride-forming elements than other samples, most of the carbon in the sample is bonded to these elements, and C for martensite formation cannot be ensured, so sufficient hardness is obtained. It is thought that it was not obtained. Experiment No. 26 is
Carbonitriding (2) conditions (surface carbon concentration and nitrogen concentration) are not sufficient, resulting in insufficient strength.
【００６７】これらに比べて、実験Ｎｏ．１０、１１、
１３〜１６は、本発明で定める組成や熱処理条件を満た
しており、熱処理前の内部強度を保ったままで表面硬度
が高められているため、剛性、強度ともに優れている。In comparison with these, the experiment No. 10, 11,
Nos. 13 to 16 satisfy the composition and heat treatment conditions defined in the present invention, and the surface hardness is increased while maintaining the internal strength before heat treatment, and therefore, both rigidity and strength are excellent.
【００６８】[0068]
【発明の効果】本発明の高剛性鋼は、加工性や靭延性を
失うことなく、剛性の大幅な向上と共に強度、特に疲労
強度にも優れたものであるから、機械部品の小型軽量化
やその他の鉄鋼材料にも好適に用いることができる。EFFECTS OF THE INVENTION The high-rigidity steel of the present invention has a great improvement in rigidity without losing workability and toughness and ductility, and is also excellent in strength, particularly fatigue strength. It can also be suitably used for other steel materials.
Claims (8)
に、ヤング率が３００ＧＰａ以上の化合物が溶製段階で
５〜５０ｖｏｌ％分散されてなる高剛性鋼において、表
面から１００μｍ深さ位置のビッカース硬さが６００以
上であり、表面から１ｍｍ以上の深さ位置のビッカース
硬さが４５０未満であることを特徴とする高疲労強度・
高剛性鋼。1. A high-rigidity steel in which a compound having a Young's modulus of 300 GPa or more is dispersed in a matrix made of iron or an iron alloy in an amount of 5 to 50 vol% in a melting stage, and Vickers hardness at a position of 100 μm depth from the surface. Is 600 or more and the Vickers hardness at a depth position of 1 mm or more from the surface is less than 450. High fatigue strength ・
High rigidity steel.
選択される少なくとも１種の元素の炭化物、窒化物、ホ
ウ化物およびそれらの複合化物の１種以上である請求項
１に記載の高疲労強度・高剛性鋼。2. The high fatigue strength according to claim 1, wherein the compound is one or more of carbides, nitrides, borides and their composites of at least one element selected from 4a and 5a group elements. -High rigidity steel.
たは２に記載の高疲労強度・高剛性鋼。3. The high fatigue strength / high rigidity steel according to claim 1, wherein the compound is TiB 2 .
（Ｔｉ／Ｂ）が質量比で２．１以上、５以下である請求
項３に記載の高疲労強度・高剛性鋼。4. The high fatigue strength / high rigidity steel according to claim 3, wherein the ratio of Ti and B (Ti / B) contained in the high rigidity steel is 2.1 or more and 5 or less in mass ratio.
る、下記式によって求められるＳＣ値およびＳＮ値の少
なくとも一方が０．４％以上であると共に、表面から１
ｍｍ以上の深さ位置における同ＳＣ値およびＳＮ値がい
ずれも０．４％未満である請求項１〜４のいずれかに記
載の高疲労強度・高剛性鋼。 ＳＣ＝全Ｃ−（0.25・Ｔｉ−0.53・Ｂ＋0.24・Ｖ＋0.13・Ｚ
ｒ＋0.13・Ｎｂ＋0.065・Ｗ） ＳＮ＝全Ｎ−（0.29・Ｔｉ−0.61・Ｂ＋0.28・Ｖ＋0.15・Ｚ
ｒ＋0.15・Ｎｂ＋0.076・Ｗ）5. At a depth of 100 μm from the surface, at least one of the SC value and the SN value determined by the following formula is 0.4% or more, and at least 1 from the surface.
The high fatigue strength / high rigidity steel according to any one of claims 1 to 4, wherein both the SC value and the SN value at a depth position of mm or more are less than 0.4%. SC = All C- (0.25 / Ti-0.53 / B + 0.24 / V + 0.13 / Z
r + 0.13 ・ Nb + 0.065 ・ W) SN = All N- (0.29 ・ Ti-0.61 ・ B + 0.28 ・ V + 0.15 ・ Z
r + 0.15 / Nb + 0.076 / W)
％以下である請求項１〜５のいずれかに記載の高疲労強
度・高剛性鋼。6. The high fatigue strength / high rigidity steel according to claim 1, wherein the Cr content in the high rigidity steel is 23 mass% or less.
る方法であって、鉄または鉄合金からなるマトリックス
中にヤング率が３００ＧＰａ以上の化合物を溶製段階で
５〜５０ｖｏｌ％分散してなる高剛性鋼の表層部に、浸
炭焼入れ、窒化焼入れ、浸炭窒化焼入れのいずれかの熱
処理を施すことを特徴とする高疲労強度・高剛性鋼の製
造方法。7. The method for producing a high-rigidity steel according to claim 1, wherein a compound having a Young's modulus of 300 GPa or more is dispersed in a matrix made of iron or an iron alloy in an amount of 5 to 50 vol% in a melting step. A method for producing high fatigue strength / high rigidity steel, characterized in that the surface layer portion of the high rigidity steel thus obtained is subjected to a heat treatment of carburizing quenching, nitriding quenching or carbonitriding quenching.
で０．１％を超え、［０．２５（Ｔｉ−２．１８Ｂ）＋
０．１８］％未満である請求項７に記載の製造方法。8. The C content in the matrix is mass%.
Exceeds 0.1% and [0.25 (Ti-2.18B) +
0.18]% or less, The manufacturing method of Claim 7.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004218069A (en) * | 2002-12-26 | 2004-08-05 | Aichi Steel Works Ltd | High rigidity steel producible by melting method, and production method therefor |
| JP2008121083A (en) * | 2006-11-14 | 2008-05-29 | Honda Motor Co Ltd | TiC-DISPERSED CAST IRON MATERIAL AND ITS PRODUCTION METHOD |
| CN102935503A (en) * | 2012-11-22 | 2013-02-20 | 广西大学 | Metal-stream powder nitrogenization method for preparing Ti(C,N) particle-reinforced iron-base composite material by in-situ reaction casting |
| WO2017173950A1 (en) * | 2016-04-05 | 2017-10-12 | 宝山钢铁股份有限公司 | Lightweight steel and steel sheet with enhanced elastic modulus, and manufacturing method thereof |
| CN115044819A (en) * | 2022-07-28 | 2022-09-13 | 西安稀有金属材料研究院有限公司 | High-hardness in-situ reinforced iron-based composite material and preparation method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09143631A (en) * | 1995-11-20 | 1997-06-03 | Yamaha Motor Co Ltd | Shaft member for vehicle |
| JPH1068048A (en) * | 1996-08-29 | 1998-03-10 | Kobe Steel Ltd | High rigidity and high toughness steel and its production |
-
2001
- 2001-09-28 JP JP2001302998A patent/JP5016172B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09143631A (en) * | 1995-11-20 | 1997-06-03 | Yamaha Motor Co Ltd | Shaft member for vehicle |
| JPH1068048A (en) * | 1996-08-29 | 1998-03-10 | Kobe Steel Ltd | High rigidity and high toughness steel and its production |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004218069A (en) * | 2002-12-26 | 2004-08-05 | Aichi Steel Works Ltd | High rigidity steel producible by melting method, and production method therefor |
| JP2008121083A (en) * | 2006-11-14 | 2008-05-29 | Honda Motor Co Ltd | TiC-DISPERSED CAST IRON MATERIAL AND ITS PRODUCTION METHOD |
| CN102935503A (en) * | 2012-11-22 | 2013-02-20 | 广西大学 | Metal-stream powder nitrogenization method for preparing Ti(C,N) particle-reinforced iron-base composite material by in-situ reaction casting |
| WO2017173950A1 (en) * | 2016-04-05 | 2017-10-12 | 宝山钢铁股份有限公司 | Lightweight steel and steel sheet with enhanced elastic modulus, and manufacturing method thereof |
| KR20180125589A (en) * | 2016-04-05 | 2018-11-23 | 바오샨 아이론 앤 스틸 유한공사 | Lightweight steel, steel sheet and manufacturing method thereof having the feature of reinforcing elastic modulus |
| JP2019513897A (en) * | 2016-04-05 | 2019-05-30 | 宝山鋼鉄股▲分▼有限公司 | Lightweight steel with improved elastic modulus, steel plate and method for producing the same |
| KR102128491B1 (en) | 2016-04-05 | 2020-07-09 | 바오샨 아이론 앤 스틸 유한공사 | Light-weight steel, steel sheet, and method for manufacturing the elastic modulus |
| US11078554B2 (en) | 2016-04-05 | 2021-08-03 | Baoshan Iron & Steel Co., Ltd. | Lightweight steel and steel sheet with enhanced elastic modulus, and manufacturing method thereof |
| CN115044819A (en) * | 2022-07-28 | 2022-09-13 | 西安稀有金属材料研究院有限公司 | High-hardness in-situ reinforced iron-based composite material and preparation method thereof |
| CN115044819B (en) * | 2022-07-28 | 2022-11-18 | 西安稀有金属材料研究院有限公司 | High-hardness in-situ reinforced iron-based composite material and preparation method thereof |
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| JP5016172B2 (en) | 2012-09-05 |
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