JPH0570925A - Carbonitriding heat treatment method for high strength gear with small strain - Google Patents
Carbonitriding heat treatment method for high strength gear with small strainInfo
- Publication number
- JPH0570925A JPH0570925A JP23660491A JP23660491A JPH0570925A JP H0570925 A JPH0570925 A JP H0570925A JP 23660491 A JP23660491 A JP 23660491A JP 23660491 A JP23660491 A JP 23660491A JP H0570925 A JPH0570925 A JP H0570925A
- Authority
- JP
- Japan
- Prior art keywords
- tooth
- less
- carbonitriding
- transformation point
- tooth surface
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Gears, Cams (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
(57)【要約】
【目的】 本発明は、浸炭窒化処理に際し、焼入れ時の
歪が小さく、かつ疲労強度が高いトランスミッションギ
アを製造することができる高強度歯車の浸炭窒化熱処理
方法を提供する。
【構成】 Ｓｉ、Ｍｎ、Ｃｒ、Ｍｏ、Ｖ等を特定の成分
範囲で含む鋼を素材とした歯車に、浸炭窒化処理を施し
た直後に、歯表面部（浸炭窒化部）のＡｒ3変態点以
上、歯内部（非浸炭窒化部）のＡｒ1 変態点以下の温度
域に保持して、その後に焼入れ焼戻しを行うことによ
り、歯表面をマルテンサイト組織にしつつ、歯内部をフ
ェライト・パーライト組織にする。
(57) [Summary] [Object] The present invention provides a carbonitriding heat treatment method for a high-strength gear, which is capable of producing a transmission gear having a low strain during quenching and a high fatigue strength in the carbonitriding treatment. [Constitution] Immediately after carbonitriding a gear made of steel containing Si, Mn, Cr, Mo, V, etc. in a specific composition range, immediately after the carbonitriding treatment, the Ar 3 transformation point of the tooth surface portion (carbonitriding portion) As described above, by maintaining the temperature inside the Ar 1 transformation point in the tooth (non-carbonitriding part) or lower and then performing quenching and tempering, the tooth surface has a martensitic structure and the tooth has a ferrite / pearlite structure. To do.
Description
【０００１】[0001]
【産業上の利用分野】本発明は、浸炭窒化熱処理方法、
特に焼入れ時の歪が少なく、騒音の少ない自動車トラン
スミッション用ギアを製造することのできる肌焼鋼の浸
炭窒化熱処理方法に関するものである。The present invention relates to a carbonitriding heat treatment method,
In particular, the present invention relates to a carbonitriding heat treatment method for case-hardening steel, which is capable of producing a gear for an automobile transmission with less distortion during quenching and less noise.
【０００２】[0002]
【従来の技術】一般に、自動車用歯車には、耐疲労強度
および表面の耐摩耗性を高めるために、肌焼鋼が使用さ
れている。この場合、肌焼鋼は歯車等の所定形状に機械
加工された後、表面硬化のために浸炭窒化処理を施され
る。すなわち、炭素含有量の比較的低い低合金鋼の表面
に炭素と窒素を浸透させ、次に焼入れ、焼戻しを施し
て、歯表面をマルテンサイトにすることで硬化させ、か
つ歯車の靱性を確保する意味から、歯車芯部を一部マル
テンサイトあるいはベイナイトを含んだフェライト・パ
ーライト組織にする。ただし、歯車芯部とは図１（Ｂ）
の網掛で示す歯車の中央部である。このように歯表面と
歯車芯部の組織差を利用することは、耐疲労強度および
靱性を得るための基本原理であり、また浸炭窒化焼入れ
法において、冷却速度の質量効果を利用することにより
十分達成されていることは周知の事実である。2. Description of the Related Art Generally, case hardening steel is used for automobile gears in order to improve fatigue resistance and surface wear resistance. In this case, the case-hardening steel is machined into a predetermined shape such as a gear and then carbonitrided for surface hardening. That is, carbon and nitrogen are infiltrated into the surface of a low alloy steel having a relatively low carbon content, and then quenching and tempering are performed to harden the tooth surface by making it martensite and secure the toughness of the gear. From the point of view, the core of the gear has a ferrite / pearlite structure that partially contains martensite or bainite. However, the gear core is shown in Fig. 1 (B).
It is the central portion of the gear shown by the mesh. Utilizing the difference in structure between the tooth surface and the gear core is a basic principle for obtaining fatigue strength and toughness, and in the carbonitriding and quenching method, it is sufficient to utilize the mass effect of the cooling rate. What has been achieved is a well-known fact.
【０００３】しかしながら、歯車芯部は質量効果により
一部マルテンサイトあるいはベイナイトを含んだフェラ
イト・パーライト組織になるものの、歯内部（図１
（Ａ）の斜線部で示される歯の浸炭層より内側の部分）
は芯部より冷速が速いため、焼入れ組織であるマルテン
サイトと一部ベイナイトの混在組織になる。この時、マ
ルテンサイト生成による変態応力（オーステナイトから
マルテンサイト組織に変化するときに生じる体積膨張に
起因する応力）が発生するため、熱処理変形の発生が避
けられず、歯車精度を維持することができない。特に、
自動車トランスミッション用ギアは、騒音に対して最も
厳しい制限があるにも拘らず、小さくかつ肉厚が薄いた
め、歯内部の組織はマルテンサイトとベイナイト組織に
なり、このことが歯車騒音の最大の原因になっている。However, although the gear core has a ferrite-pearlite structure containing a part of martensite or bainite due to the mass effect, the inside of the tooth (see FIG. 1).
(A portion inside the carburized layer of the tooth shown by the hatched portion in (A))
Has a faster cooling rate than the core, and therefore has a mixed structure of martensite, which is a quenching structure, and part of bainite. At this time, transformation stress due to martensite formation (stress due to volume expansion that occurs when changing from austenite to martensite structure) occurs, so that heat treatment deformation cannot be avoided and gear precision cannot be maintained. .. In particular,
Despite the strictest restrictions on noise, automotive transmission gears are small and thin, resulting in internal tooth structures of martensite and bainite, which are the major contributors to gear noise. It has become.
【０００４】そこで従来は、焼入れ歪に対して歯車研削
を追加することにより、精度を向上させる方法が用いら
れている。また、イオン窒化、ガス軟窒化やタフトライ
ドなどの低温で行う窒化処理等も検討されている。さら
に、特開昭５５−６４５６号公報では、等温焼きなまし
処理によりフェライト・パーライト組織にした後、軟窒
化処理により表面のみ硬化する方法が開示されており、
また一旦フェライト・パーライト組織にした後、窒化処
理により表面層のＡ1 変態点を下げてオーステナイト化
を促進させ、急冷によって表面層のみマルテンサイト組
織を得る方法（金属臨時増刊号、１９９０年，Ｖｏ１
８，Ｐ２５）が開示されている。Therefore, conventionally, a method of improving accuracy by adding gear grinding to quenching strain has been used. In addition, nitriding treatments performed at low temperatures such as ion nitriding, gas soft nitriding, and tuftride are being studied. Further, Japanese Patent Laid-Open No. 55-6456 discloses a method in which after isothermal annealing treatment to form a ferrite / pearlite structure, only the surface is hardened by soft nitriding treatment.
In addition, a method in which after the ferrite / pearlite structure is once formed, the A 1 transformation point of the surface layer is lowered by nitriding treatment to promote austenite formation and a martensite structure is obtained only in the surface layer by quenching (Metal Temporary Special Issue, 1990, Vo1
8, P25) is disclosed.
【０００５】[0005]
【発明が解決しようとする課題】しかし、歯車機械研削
では浸炭窒化層を部分的に削り取ることから、製造工程
数が増加するほか、複雑な形状部品には適用しがたく、
また表面硬さや残留応力にムラを生ずることとなり、品
質上の問題があった。一方、イオン窒化、ガス軟窒化や
タフトライドおよび特開昭５５−６４５６号公報の方法
では、焼入れ硬化層が薄く、また内部硬度が低いため、
十分な疲労強度が得られない。また、窒化処理により表
面層のＡ1 変態点を下げてオーステナイト化を促進さ
せ、急冷によって表面層のみマルテンサイト組織を得る
方法は、浸炭窒化部に異常化合物層の形成による硬度低
下が生じ、また内部硬度が低いため十分な疲労強度が得
られない、という問題を有してした。However, in the mechanical grinding of gears, the carbonitrided layer is partially shaved off, which increases the number of manufacturing steps and makes it difficult to apply to parts having complicated shapes.
Further, the surface hardness and the residual stress are uneven, which is a quality problem. On the other hand, in the methods of ion nitriding, gas soft nitriding, tufftride and JP-A-55-6456, the quench hardened layer is thin and the internal hardness is low.
Sufficient fatigue strength cannot be obtained. Further, the method of lowering the A 1 transformation point of the surface layer by nitriding treatment to promote austenitization and obtaining the martensite structure only in the surface layer by quenching causes a decrease in hardness due to formation of an abnormal compound layer in the carbonitrided portion, and There was a problem that sufficient fatigue strength could not be obtained due to the low internal hardness.
【０００６】すなわち、従来の機械加工法では経済性と
歯車自身の品質を犠牲にしたものであり、材料側からの
取組みも、歯内部のマルテンサイト防止により歪は軽減
できるものの、歯車本来の特性である高疲労強度を犠牲
にしたものであり、高強度化を維持しつつ歯内部を完全
なフェライトとパーライト組織にする有効な方法が望ま
れている。That is, the conventional machining method sacrifices economy and the quality of the gear itself, and even when the material is used, distortion can be reduced by preventing martensite inside the tooth, but the original characteristics of the gear are obtained. This is a sacrifice of high fatigue strength, which is an effective method for forming a complete ferrite and pearlite structure inside the tooth while maintaining high strength.
【０００７】[0007]
【課題を解決するための手段】本発明者らは、このよう
な実情に対処して、浸炭窒化焼入れ処理による歪の発生
が少なく、かつ優れた硬化特性が得られる浸炭窒化歯車
用の素材を開発するために多くの研究を行ってきた。す
なわち、浸炭窒化処理は、表面層のみＡ1 変態点を下げ
るため、歯内部をフェライト・パーライト組織にしつつ
表面層のみオーステナイトにする極めて有効な方法であ
り、該処理における表層化合物層の生成挙動および歯内
部強度は主に鋼材組成に依存する。従って、高強度化を
維持しつつ歯内部を完全なフェライトとパーライト組織
にする有効な方法の開発を目的に、浸炭窒化条件および
鋼材組成の両面から詳細な検討を加えた結果、以下の知
見を得た。Means for Solving the Problems The present inventors have dealt with such an actual situation and have developed a material for carbonitrided gears in which distortion due to carbonitriding and quenching treatment is small and excellent hardening characteristics are obtained. Much research has been done to develop it. That is, the carbonitriding treatment is an extremely effective method for reducing the A 1 transformation point only in the surface layer and thus making only the surface layer austenite while forming the ferrite / pearlite structure inside the tooth. The internal strength of the tooth mainly depends on the steel composition. Therefore, for the purpose of developing an effective method for forming a complete ferrite and pearlite structure inside the tooth while maintaining high strength, detailed investigation was conducted from both aspects of carbonitriding conditions and steel material composition. Obtained.
【０００８】浸炭窒化処理において，表層化合物層、
内部酸化層および不完全焼入れ層の生成が表層の硬度低
下をもたらす。これらの生成防止にはＣｒおよびＳｉを
低減しつつ、表層が十分に硬化するように焼入れ性を高
めておくことが有効である。 硬化層深さの増大には、浸炭窒化処理により表面層か
ら深くまでオーステナイト化することが必要であり、こ
れには表層の化合物層の生成を抑制することが有効であ
る。In the carbonitriding treatment, the surface compound layer,
The formation of the internal oxide layer and the incompletely hardened layer causes a decrease in the hardness of the surface layer. To prevent the formation of these, it is effective to increase the hardenability so that the surface layer is sufficiently hardened while reducing Cr and Si. In order to increase the depth of the hardened layer, it is necessary to deepen the austenite from the surface layer by carbonitriding, and it is effective to suppress the formation of the surface compound layer.
【０００９】歯内部がフェライト・パーライト組織に
なることによる硬度低下は、炭窒化物の析出硬化および
微細化効果により抑制できる。さらに、化合物層の生成
抑制の観点より、特定量のＶ添加が有効である。そこ
で、こうした知見に基づいて、具体的な達成手段を明ら
かにするため、さらに研究検討を重ね、特定の化学組成
の肌焼鋼より製造された歯車に、浸炭窒化処理を施した
直後に、特定の温度範囲に所定時間保持し、その後焼入
れ、焼戻しを行うことにより、表面硬さを低下させず
に、歯内部の組織をフェライトと微細パーライト組織と
し、かくして騒音の発生源となる歯の焼入れ時の歪を大
幅に低減し、かつ静粛性を著しく向上させ得る新しい歯
車の浸炭窒化熱処理方法を完成させた。The decrease in hardness due to the ferrite / pearlite structure inside the tooth can be suppressed by the precipitation hardening and miniaturization effects of carbonitride. Furthermore, from the viewpoint of suppressing the formation of the compound layer, addition of a specific amount of V is effective. Therefore, based on these findings, in order to clarify the concrete means for achieving it, further research and study was conducted, and immediately after carbonitriding the gear manufactured from case hardening steel of a specific chemical composition, it was specified. By holding in the temperature range for a specified time and then quenching and tempering, the internal structure of the tooth is made into a ferrite and fine pearlite structure without lowering the surface hardness, thus quenching the tooth which is the source of noise. We have completed a new carbonitriding heat treatment method for gears that can significantly reduce the strain and improve the quietness significantly.
【００１０】すなわち、本発明の要旨とするところは下
記のとおりである。 （１）重量％で、Ｃ：０．１％以上０．３％未満、Ｓ
ｉ：０．１５％未満、Ｍｎ：０．３０％以上１．５０％
未満、Ｃｒ：０．３０％以上１．００％未満、Ｍｏ：
０．１０％以上１．００％未満、Ｖ：０．０５％以上
１．００％未満を含有し、残部Ｆｅおよび不純物よりな
る鋼を素材とした歯車に、浸炭窒化処理を施し、その後
直ちに、あるいはいったん歯表面部（浸炭窒化部）のＡ
ｒ1 変態点以下の温度域まで冷却し、再度歯表面部（浸
炭窒化部）のＡｃ3 変態点以上に加熱した後、歯表面部
（浸炭窒化部）のＡｒ3 変態点以上で歯内部（非浸炭窒
化部）のＡｒ1 変態点以下の温度域に５分以上２時間未
満保持して、歯表面をオーステナイト状態に保ちつつ歯
内部を微細なフェライト・パーライトにし、しかる後に
焼入れ、焼戻しを行うことにより、歯内部を微細なフェ
ライト・パーライト組織とすることを特徴とする歪の小
さい高強度歯車の浸炭窒化熱処理方法。That is, the gist of the present invention is as follows. (1)% by weight, C: 0.1% or more and less than 0.3%, S
i: less than 0.15%, Mn: 0.30% or more and 1.50%
Less than, Cr: 0.30% or more and less than 1.00%, Mo:
Gears made of steel containing 0.10% or more and less than 1.00% and V: 0.05% or more and less than 1.00% with the balance Fe and impurities are carbonitrided, and immediately thereafter, Or once A of the tooth surface part (carbonitriding part)
After cooling to a temperature range below the r 1 transformation point and heating again to above the Ac 3 transformation point of the tooth surface portion (carbonitriding portion), inside the tooth at the Ar 3 transformation point of the tooth surface portion (carbonitriding portion) or above ( Hold the temperature in the temperature range below the Ar 1 transformation point of the non-carbonitriding part) for 5 minutes or more and less than 2 hours to form a fine ferrite pearlite inside the tooth while keeping the tooth surface in the austenite state, followed by quenching and tempering. Thus, a carbonitriding heat treatment method for a high-strength gear with small strain, characterized in that the inside of the tooth has a fine ferrite-pearlite structure.
【００１１】ただし、歯内部とは図１（Ａ）の斜線部で
示される歯の浸炭層より内側である。 （２）重量％で、Ｃ：０．１％以上０．３％未満、Ｓ
ｉ：０．１５％未満、Ｍｎ：０．３０％以上１．５０％
未満、Ｃｒ：０．３０％以上１．００％未満、Ｍｏ：
０．１０％以上１．００％未満、Ｖ：０．０５％以上
１．００％未満を含むとともに、Ｎｂ：０．０２％以上
０．２０％以下、Ｔｉ：０．０１％以上０．２０％以下
の１種以上を含有し、残部Ｆｅおよび不純物よりなる鋼
を素材とした歯車に、浸炭窒化処理を施し、その後直ち
に、あるいはいったん歯表面部（浸炭窒化部）のＡｒ1
変態点以下の温度域まで冷却し、再度歯表面部（浸炭窒
化部）のＡｃ3 変態点以上に加熱した後、歯表面部（浸
炭窒化部）のＡｒ3 変態点以上で歯内部（非浸炭窒化
部）のＡｒ1 変態点以下の温度域に５分以上２時間未満
保持して、歯表面をオーステナイト状態に保ちつつ歯内
部を微細なフェライト・パーライトにし、しかる後に焼
入れ、焼戻しを行うことにより、歯内部を微細なフェラ
イト・パーライトとすることを特徴とする歪の小さい高
強度歯車の浸炭窒化熱処理方法。However, the inside of the tooth is the inside of the carburized layer of the tooth shown by the hatched portion in FIG. 1 (A). (2) In% by weight, C: 0.1% or more and less than 0.3%, S
i: less than 0.15%, Mn: 0.30% or more and 1.50%
Less than, Cr: 0.30% or more and less than 1.00%, Mo:
0.10% or more and less than 1.00%, V: 0.05% or more and less than 1.00%, Nb: 0.02% or more and 0.20% or less, Ti: 0.01% or more and 0.20 or less %, One or more of the steel containing the balance Fe and impurities is carbonitrided and then immediately or once Ar 1 of the tooth surface (carbonitriding part)
After cooling to a temperature range below the transformation point and heating again to the Ac 3 transformation point on the tooth surface (carbonitriding portion) or higher, inside the tooth (non-carburized) above the Ar 3 transformation point on the tooth surface (carbonitriding portion). By maintaining the temperature range below the Ar 1 transformation point of the nitrided part) for 5 minutes or more and less than 2 hours to make the tooth surface fine a ferrite pearlite while keeping the tooth surface in an austenite state, and then quenching and tempering , A method of carbonitriding heat treatment of a high-strength gear with small strain, characterized in that the inside of the tooth is made of fine ferrite pearlite.
【００１２】ただし、歯内部とは図１（Ａ）の斜線部で
示される歯の浸炭層より内側である。以下に本発明の各
構成要件について説明する。最初に、本発明の浸炭窒化
熱処理方法が適用できる合金鋼の化学成分について述べ
る。However, the inside of the tooth is the inside of the carburized layer of the tooth shown by the hatched portion in FIG. 1 (A). Each constituent element of the present invention will be described below. First, the chemical composition of the alloy steel to which the carbonitriding heat treatment method of the present invention can be applied will be described.
【００１３】本発明における合金鋼は、浸炭窒化処理を
行う炉中の冷却で、歯内部の組織をフェライト・パーラ
イトにでき、しかも歯車としての剛性や靱性等を維持す
るのに十分な内部硬さでなければならない。一方、この
合金鋼は浸炭窒化されるため、浸炭窒化処理により悪影
響を受けない化学成分でなければならない。Ｃは自動車
用歯車として必要な強度、特に芯部強度を確保するため
に添加する元素であるが、０．１％未満ではこのような
効果を十分に得ることができず、０．３％以上では靱性
が低下して脆くなり、浸炭用鋼として使用が困難となる
ので、その含有量を０．１％以上０．３％未満とした。The alloy steel according to the present invention can be made into a ferrite / pearlite structure inside the tooth by cooling in a furnace for carbonitriding, and has an internal hardness sufficient to maintain rigidity and toughness as a gear. Must. On the other hand, since this alloy steel is carbonitrided, it must have a chemical composition that is not adversely affected by carbonitriding. C is an element added to secure the strength required for automobile gears, especially the core strength, but if it is less than 0.1%, such an effect cannot be sufficiently obtained and 0.3% or more. In that case, the toughness decreases and the steel becomes brittle, and it becomes difficult to use it as a carburizing steel. Therefore, the content thereof is set to 0.1% or more and less than 0.3%.
【００１４】Ｓｉは浸炭用鋼の粒界酸化に著しく悪影響
を及ぼす元素であり、含有量は０．１５％以上では浸炭
層に顕著な粒界酸化が形成され、浸炭用鋼の材質特性が
劣化するため、その含有量を０．１５％未満とした。Ｍ
ｎは鋼に強度、靱性、焼入れ性を与えるのに必要な元素
であるが、１．５０％以上では熱間圧延後の冷却におい
てベイナイトやマルテンサイトの硬質な組織になり、そ
の後の切削等の二次加工には適さなくなるために１．５
０％未満とする。しかし、Ｍｎの添加量が０．３０％未
満では焼入れ性向上の効果が十分でなく、その含有量は
０．３０％以上とする。Si is an element that exerts a significant adverse effect on the grain boundary oxidation of carburizing steel, and when the content is 0.15% or more, remarkable grain boundary oxidation is formed in the carburizing layer, and the material properties of the carburizing steel deteriorate. Therefore, the content is set to less than 0.15%. M
n is an element necessary for imparting strength, toughness, and hardenability to steel, but if it is 1.50% or more, it becomes a hard structure of bainite or martensite in cooling after hot rolling, and after cutting etc. 1.5 because it is not suitable for secondary processing
It is less than 0%. However, if the addition amount of Mn is less than 0.30%, the effect of improving the hardenability is not sufficient, and the content thereof is 0.30% or more.
【００１５】Ｃｒは鋼の浸炭窒化層に化合物層を形成
し、表面硬度を低下し、併せてＮの鉄中への固溶を阻害
し、また浸炭窒化層のオーステナイト化温度を上げ、オ
ーステナイト化を阻害する。１．００％以上では顕著に
化合物層を形成し、窒化処理を阻害するため１．００％
未満とする。しかし、Ｃｒの添加量が０．３０％未満で
は焼入れ性向上の効果が十分でなく、その含有量は０．
３０％以上とする。Cr forms a compound layer in the carbonitriding layer of steel, lowers the surface hardness, and also inhibits the solid solution of N in iron, and raises the austenitizing temperature of the carbonitriding layer to form austenite. Inhibit. If it is 1.00% or more, a compound layer is formed remarkably and the nitriding treatment is hindered.
Less than However, if the added amount of Cr is less than 0.30%, the effect of improving the hardenability is not sufficient, and the content thereof is 0.
30% or more.
【００１６】Ｍｏは粒界酸化層を形成することなしに鋼
の耐摩耗性、焼入れ性、機械的特性を向上し、特に歯内
部の硬度上昇に有用な元素であり、０．１０％未満では
その効果が十分でなく、１．００％以上では靱性を劣化
させるため、０．１０％以上１．００％未満とする。Ｖ
は炭窒化物の析出硬化により、歯内部のフェライト・パ
ーライトの硬度上昇をもたらす元素であるが、０．０５
％未満ではその効果が十分でなく、１．００％以上を含
有しても効果は飽和するため、０．０５％以上１．００
％未満とする。Mo is an element that improves the wear resistance, hardenability and mechanical properties of steel without forming an intergranular oxide layer and is particularly useful for increasing the hardness inside the tooth. The effect is not sufficient, and if it is 1.00% or more, the toughness is deteriorated, so the content is made 0.10% or more and less than 1.00%. V
Is an element that increases the hardness of ferrite / pearlite inside the tooth due to the precipitation hardening of carbonitride.
%, The effect is not sufficient, and the effect is saturated even if 1.00% or more is contained, so 0.05% or more and 1.00
Less than%.
【００１７】ＴｉおよびＮｂは炭窒化物を生成し、浸炭
結晶粒の微細化に効果のある元素であり、その効果を得
るには１種以上の元素をＮｂで０．０２％以上およびＴ
ｉで０．０１％以上の含有が必要である。しかし、Ｎｂ
で０．２０％を超えて、Ｔｉで０．２０％を超えて含有
しても効果は飽和するため、上限をＮｂで０．２０％、
Ｔｉで０．２０％とする。Ti and Nb are elements that generate carbonitrides and are effective in refining carburized crystal grains. To obtain the effect, at least one element is 0.02% or more in Nb and T.
It is necessary that the content of i is 0.01% or more. But Nb
If the content of Ti exceeds 0.20% and the content of Ti exceeds 0.20%, the effect is saturated, so the upper limit is 0.20% for Nb,
Ti is set to 0.20%.
【００１８】上記成分のほか、以下に示す元素を添加す
ることにより、よりいっそう特性の向上が可能である。
ＣａはＭｎＳの延伸抑制のために必要な元素であり、歯
車の疲労における異方性を軽減する。ＭｎＳの延伸抑制
効果を与えるために、Ｃａを０．００１０％以上含有さ
せる。しかし、０．０１０％を超えて含有させても、そ
の効果は飽和して経済性を損うため上限を０．０１０％
とする。The characteristics can be further improved by adding the following elements in addition to the above components.
Ca is an element necessary for suppressing the stretching of MnS and reduces anisotropy in fatigue of gears. In order to give the effect of suppressing the stretching of MnS, Ca is contained in an amount of 0.0010% or more. However, even if the content exceeds 0.010%, the effect is saturated and the economy is impaired, so the upper limit is 0.010%.
And
【００１９】次に、浸炭窒化法としては、ガス浸炭窒化
法または液体浸炭窒化法が好ましく、また浸炭窒化深さ
は表層硬さおよび残留応力の観点から０．５mm以上であ
ることが好ましい。表面炭素量が共析以上、Ａcm以下の
カーボンポテンシャルにて８５０〜９８０℃の温度で浸
炭窒化処理することにより、非浸炭窒化部に比べ浸炭窒
化部のＡｒ 3 変態点が約５０℃下がる（浸炭窒化温度：
９３０℃、カーボンポテンシャル：０．９％、Ｎポテン
シャル：２％、ＪＩＳ ＳＣＭ４２０での、本発明者ら
の実験例）。Next, as the carbonitriding method, gas carbonitriding is used.
Method or liquid carbonitriding method is preferred, and carbonitriding depth
Is 0.5 mm or more from the viewpoint of surface hardness and residual stress.
Preferably. Surface carbon content is more than eutectoid and less than Acm
Immerse at a temperature of 850-980 ° C with carbon potential
By carbonitriding, carbonitriding compared to non-carbonitriding parts
Ar part 3The transformation point drops by about 50 ° C (carbonitriding temperature:
930 ° C, carbon potential: 0.9%, N potene
Shall: 2%, the present inventors at JIS SCM420
Experimental example).
【００２０】浸炭窒化後炉冷等により６６０〜７００℃
（歯表面部のＡｒ3変態点以上で歯内部のＡｒ1 変態点
以下）に冷却した後、一定時間保持することにより、非
浸炭窒化部の歯内部をフェライトと微細パーライトに変
態させつつ、歯表面の浸炭窒化部をオーステナイト状態
に維持する。保持時間は温度の均一性および熱処理コス
トより、５分以上２時間未満が好ましい（これ以上保持
時間を長くしても品質上での利点はなく、また不経済で
ある）。After carbonitriding, the temperature is 660 to 700 ° C. by cooling the furnace.
After cooling to a temperature higher than the Ar 3 transformation point on the tooth surface and lower than the Ar 1 transformation point inside the tooth, and holding it for a certain period of time, the tooth inside the non-carbonitrided portion is transformed into ferrite and fine pearlite, The carbonitrided portion of the surface is maintained in an austenitic state. The holding time is preferably 5 minutes or more and less than 2 hours in view of the uniformity of temperature and the heat treatment cost (longer holding times do not have an advantage in quality and are uneconomical).
【００２１】浸炭窒化部の結晶粒を細粒化する、より好
ましい条件としては、浸炭窒化後、歯表面部のＡｒ1 変
態点以下まで徐冷し、次に歯表面部のＡｃ3 変態点以上
に再加熱する。この時、浸炭窒化部のオーステナイト粒
の細粒化が図られる。次に歯表面部のＡｒ3 変態点以上
で歯内部のＡｒ1 変態点以下にした後、一定時間保持す
ることにより、非浸炭窒化部の歯内部は、微細なフェラ
イト・パーライトままで歯表面の浸炭窒化部のみ細粒の
オーステナイトに変態する。保持時間は温度の均一性お
よび熱処理コストより、５分以上２時間未満が好まし
い。As a more preferable condition for making the crystal grains of the carbonitrided portion finer, after carbonitriding, the tooth surface is gradually cooled to the Ar 1 transformation point or lower, and then the tooth surface portion is Ac 3 transformation point or higher. Reheat to. At this time, the austenite grains in the carbonitrided portion are refined. Next, after the Ar 3 transformation point of the tooth surface portion is set to be equal to or lower than the Ar 1 transformation point of the inside of the tooth, and the tooth surface of the non-carbonitrided portion is kept as a fine ferrite / pearlite as it is after the Ar 1 transformation point of the inside of the tooth is kept for a certain time. Only the carbonitrided part transforms into fine-grained austenite. The holding time is preferably 5 minutes or more and less than 2 hours in view of temperature uniformity and heat treatment cost.
【００２２】以上のように、表面をオーステナイト化
し、歯内部をフェライトと微細パーライトにし、しかる
後に油あるいは塩浴中で焼入れすることにより、歯表面
の浸炭窒化部は全てマルテンサイトにでき、既に変態を
終了している歯内部は焼きの入っていないフェライトと
微細パーライトに維持できる。その後、浸炭窒化部の内
部応力の除去および強さ、ねばさを増すために、１５０
〜２００℃の焼戻し処理を行う。As described above, by austenitizing the surface, making ferrite and fine pearlite inside the tooth, and then quenching in an oil or salt bath, all the carbonitrided parts of the tooth surface can be made into martensite and already transformed. The inside of the finished tooth can be maintained with unhardened ferrite and fine pearlite. After that, in order to remove the internal stress of the carbonitriding part and increase the strength and resilience,
Perform a tempering process at ~ 200 ° C.
【００２３】以下に実施例を挙げてさらに説明する。Hereinafter, the present invention will be further described with reference to examples.
【００２４】[0024]
【実施例】表１に示す化学成分の鋼を溶製し、１６２mm
角ビレットに分塊圧延した後、熱間圧延にて５０mmφ棒
鋼に仕上げた。次に、得られた棒鋼を熱間鍛造および焼
ならしし、その後機械加工により、外径８７mm、モジュ
ール３、歯数２７、歯幅２０mmの歯車を製作し、これら
を試料として浸炭窒化処理を施した。まず、試料をカー
ボンポテンシャル：０．９％、Ｎポテンシャル：２％、
温度：９３０℃で浸炭窒化した後、No. １は歯表面部お
よび歯内部のＡｒ3 変態点超の８４０℃、No. ２は歯内
部のＡｒ1 変態点超で表面部のＡｒ3 変態点以上の７５
０℃、No. ３は歯表面部のＡｒ3 変態点未満の６３０℃
まで炉冷し、３０分保持後、それぞれを１３０℃の油浴
中で冷却した。No. ４〜No. １１は表１に示す歯表面部
（浸炭窒化部）のＡｒ3 変態点以上で歯内部（非浸炭窒
化部）のＡｒ1 変態点以下の温度に、No. １２〜No.１
６は歯表面部のＡｒ1 変態点以下の６００℃まで徐冷
し、次に歯表面部のＡｃ3 変態点以上の８５０℃に再加
熱し、その後歯内部（非浸炭窒化部）のＡｒ1 変態点以
下で歯表面部（浸炭窒化部）のＡｒ3 変態点以上の温度
に、各々３０分保持して、その後１３０℃の油浴中で冷
却した。次いで、全ての試料とも１８０℃、１時間の焼
戻しを行った。また歪量はＪＩＳ Ｂ１７０２により歯
形誤差を測定し、併せて表１および表２に示した。Example: Steel having the chemical composition shown in Table 1 was melted to 162 mm.
After slab-rolling into square billets, 50 mmφ steel bar was finished by hot rolling. Next, the steel bar obtained is hot forged and normalized, and then machined to produce a gear having an outer diameter of 87 mm, a module 3, 27 teeth and a tooth width of 20 mm. gave. First, the sample is carbon potential: 0.9%, N potential: 2%,
After carbonitriding at a temperature of 930 ° C, No. 1 is 840 ° C above the Ar 3 transformation point on the tooth surface and inside the tooth, and No. 2 is above the Ar 1 transformation point inside the tooth and above the Ar 3 transformation point on the surface. More than 75
0 ℃, No. 3 is 630 ℃, which is lower than the Ar 3 transformation point of the tooth surface.
After furnace cooling to 30 minutes and holding for 30 minutes, each was cooled in an oil bath at 130 ° C. No. 4 to No. 11 are the temperatures shown in Table 1 above the Ar 3 transformation point of the tooth surface (carbonitriding portion) and below the Ar 1 transformation point of the inside of the tooth (non-carbonitriding portion), and No. 12 to No. .1
No. 6 was gradually cooled to 600 ° C. below the Ar 1 transformation point of the tooth surface, then reheated to 850 ° C. above the Ac 3 transformation point of the tooth surface, and then Ar 1 inside the tooth (non-carbonitrided portion). The tooth surface portion (carbonitrided portion) was kept at a temperature not lower than the Ar 3 transformation point below the transformation point for 30 minutes, and then cooled in an oil bath at 130 ° C. Then, all samples were tempered at 180 ° C. for 1 hour. For the amount of strain, the tooth profile error was measured according to JIS B1702, and is also shown in Table 1 and Table 2.
【００２５】歯内部のＡｒ3 変態点超で焼入れしたNo.
１は歯内部がマルテンサイトとなり、歯形歪量も多く、
また歯内部のＡｒ1 変態点超で表面部のＡｒ3 変態点以
上で焼入れしたNo. ２では歯内部は一部マルテンサイト
を含んだフェライト・パーライト組織になるため、歯形
歪量の低減も十分ではない。また、歯表面部のＡｒ3 未
満で焼入れしたNo. ３は、表面部もベイナイトとパーラ
イト組織となり、歯車として必要な表面硬さを得ること
ができない。No. No. hardened above the Ar 3 transformation point inside the tooth
In No. 1, the inside of the tooth becomes martensite, and the tooth profile distortion is large,
Also, in No. 2 which is hardened above the Ar 1 transformation point inside the tooth and above the Ar 3 transformation point in the surface, the tooth interior has a ferrite / pearlite structure that partially contains martensite, so the reduction of tooth profile distortion is sufficient. is not. Further, in No. 3 hardened with less than Ar 3 of the tooth surface portion, the surface portion also has a bainite and pearlite structure, and the surface hardness required as a gear cannot be obtained.
【００２６】さらに、歯表面部のＡｒ3 変態点以上で、
かつ歯内部のＡｒ1 変態点以下の温度で焼入れしている
ものの、本発明範囲よりＭｎが高いNo. ４は、歯形歪量
は少ないにもかかわらず、歯内部硬度が高すぎ、靱性が
低く、実用には適さない。さらに、本発明範囲よりＶが
少なすぎるNo. ５は、歯形歪量は少ないものの、歯内部
硬度が不十分で、実用には適さない。Furthermore, above the Ar 3 transformation point of the tooth surface,
Moreover, although quenching is performed at a temperature below the Ar 1 transformation point inside the tooth, No. 4 having a higher Mn than the range of the present invention has a small tooth profile distortion amount, but the tooth internal hardness is too high and the toughness is low. , Not suitable for practical use. Further, No. 5 in which V is too small compared to the range of the present invention has a small tooth profile distortion amount, but the tooth internal hardness is insufficient and is not suitable for practical use.
【００２７】これに対して本発明の範囲内にあるNo. ６
〜１６では何れも歯内部はフェライト・パーライト組織
になり、歯内部の硬度も十分であり、歯形歪量も著しく
低減でき、また内部酸化層と不完全焼入れ層の抑制によ
り、疲労強度も高いことが明らかである。On the other hand, No. 6 within the scope of the present invention
In all of ~ 16, the inside of the tooth has a ferrite-pearlite structure, the hardness inside the tooth is sufficient, the tooth profile distortion amount can be significantly reduced, and the fatigue strength is high due to the suppression of the internal oxide layer and the incompletely hardened layer. Is clear.
【００２８】[0028]
【表１】 [Table 1]
【００２９】[0029]
【表２】 [Table 2]
【００３０】[0030]
【発明の効果】以上説明してきたように、本発明は浸炭
窒化焼入れにより製造される自動車用歯車の歯内部をフ
ェライト・パーライト組織にすることにより熱処理歪の
低減を図り、同時に表層の組織制御により疲労強度の向
上を図った、騒音の少ない高強度の自動車トランスミッ
ション用ギアを提供するものであり、工業上の効果は極
めて顕著なものがある。As described above, according to the present invention, the heat treatment strain is reduced by forming the ferrite / pearlite structure inside the teeth of the automobile gear manufactured by carbonitriding and quenching, and at the same time, by controlling the structure of the surface layer. The present invention provides a high-strength automotive transmission gear with less noise and improved fatigue strength, and has an extremely remarkable industrial effect.
【図１】（Ａ）は歯車の歯内部および（Ｂ）は歯車芯部
の説明図である。FIG. 1A is an explanatory diagram of a tooth inside of a gear and FIG. 1B is an explanatory diagram of a gear core portion.
Claims (2)
満、Ｓｉ：０．１５％未満、Ｍｎ：０．３０％以上１．
５０％未満、Ｃｒ：０．３０％以上１．００％未満、Ｍ
ｏ：０．１０％以上１．００％未満、Ｖ：０．０５％以
上１．００％未満を含有し、残部Ｆｅおよび不純物より
なる鋼を素材とした歯車に、浸炭窒化処理を施し、その
後直ちに、あるいはいったん歯表面部（浸炭窒化部）の
Ａｒ1変態点以下の温度域まで冷却し、再度歯表面部
（浸炭窒化部）のＡｃ3変態点以上に加熱した後、歯表
面部（浸炭窒化部）のＡｒ3 変態点以上で歯内部（非浸
炭窒化部）のＡｒ1 変態点以下の温度域に５分以上２時
間未満保持して、歯表面をオーステナイト状態に保ちつ
つ歯内部を微細なフェライト・パーライトにし、しかる
後に焼入れ、焼戻しを行うことにより、歯内部を微細な
フェライト・パーライト組織とすることを特徴とする歪
の小さい高強度歯車の浸炭窒化熱処理方法。ただし、歯
内部とは図１（Ａ）の斜線部で示される歯の浸炭層より
内側である。1. By weight%, C: 0.1% or more and less than 0.3%, Si: 0.15% or less, Mn: 0.30% or more 1.
Less than 50%, Cr: 0.30% or more and less than 1.00%, M
O: 0.10% or more and less than 1.00%, V: 0.05% or more and less than 1.00% are contained, and gears made of steel composed of the balance Fe and impurities are carbonitrided, and then Immediately or after cooling to a temperature range below the Ar 1 transformation point of the tooth surface portion (carbonitriding portion) and heating again to above the Ac 3 transformation point of the tooth surface portion (carbonitriding portion), the tooth surface portion (carburizing portion) Hold the temperature within the temperature range below the Ar 3 transformation point of the nitrided portion) and below the Ar 1 transformation point of the non-carbonitrided portion for 5 minutes or more and less than 2 hours to keep the tooth surface in an austenite state and A carbonitriding heat treatment method for high-strength gears with small strains, characterized in that a fine ferrite-pearlite structure is formed inside the tooth by forming a suitable ferrite-pearlite material, and then quenching and tempering. However, the inside of the tooth is the inside of the carburized layer of the tooth shown by the hatched portion in FIG.
満、Ｓｉ：０．１５％未満、Ｍｎ：０．３０％以上１．
５０％未満、Ｃｒ：０．３０％以上１．００％未満、Ｍ
ｏ：０．１０％以上１．００％未満、Ｖ：０．０５％以
上１．００％未満を含むとともに、Ｎｂ：０．０２％以
上０．２０％以下、Ｔｉ：０．０１％以上０．２０％以
下の１種以上を含有し、残部Ｆｅおよび不純物よりなる
鋼を素材とした歯車に、浸炭窒化処理を施し、その後直
ちに、あるいはいったん歯表面部（浸炭窒化部）のＡｒ
1 変態点以下の温度域まで冷却し、再度歯表面部（浸炭
窒化部）のＡｃ3 変態点以上に加熱した後、歯表面部
（浸炭窒化部）のＡｒ3 変態点以上で歯内部（非浸炭窒
化部）のＡｒ1 変態点以下の温度域に５分以上２時間未
満保持して、歯表面をオーステナイト状態に保ちつつ歯
内部を微細なフェライト・パーライトにし、しかる後に
焼入れ、焼戻しを行うことにより、歯内部を微細なフェ
ライト・パーライトとすることを特徴とする歪の小さい
高強度歯車の浸炭窒化熱処理方法。ただし、歯内部とは
図１（Ａ）の斜線部で示される歯の浸炭層より内側であ
る。2. In weight%, C: 0.1% or more and less than 0.3%, Si: less than 0.15%, Mn: 0.30% or more 1.
Less than 50%, Cr: 0.30% or more and less than 1.00%, M
O: 0.10% or more and less than 1.00%, V: 0.05% or more and less than 1.00%, Nb: 0.02% or more and 0.20% or less, Ti: 0.01% or more and 0 Gears made of steel that contains 20% or less of one type or more and the balance of Fe and impurities is carbonitrided, and then immediately or once after the tooth surface (carbonitrided part) Ar
After cooling to a temperature range of 1 transformation point or less and heating again to the Ac 3 transformation point of the tooth surface portion (carbonitriding portion) or more, after the Ar 3 transformation point of the tooth surface portion (carbonitriding portion) or more, the inside of the tooth (non (Carbonitriding part) Hold the temperature within the Ar 1 transformation point for 5 minutes or more and less than 2 hours to make the tooth surface fine ferrite pearlite while keeping the tooth surface in an austenite state, and then quench and temper. By this, a carbonitriding heat treatment method for a high-strength gear with small strain, characterized in that the inside of the tooth is made of fine ferrite pearlite. However, the inside of the tooth is the inside of the carburized layer of the tooth shown by the hatched portion in FIG.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3236604A JP2549039B2 (en) | 1991-09-17 | 1991-09-17 | Carbonitriding heat treatment method for high strength gears with small strain |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3236604A JP2549039B2 (en) | 1991-09-17 | 1991-09-17 | Carbonitriding heat treatment method for high strength gears with small strain |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0570925A true JPH0570925A (en) | 1993-03-23 |
| JP2549039B2 JP2549039B2 (en) | 1996-10-30 |
Family
ID=17003105
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3236604A Expired - Fee Related JP2549039B2 (en) | 1991-09-17 | 1991-09-17 | Carbonitriding heat treatment method for high strength gears with small strain |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2549039B2 (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0769566A1 (en) | 1995-09-29 | 1997-04-23 | Toa Steel Co., Ltd. | Case hardening steel for gears |
| WO1998027242A1 (en) * | 1996-12-17 | 1998-06-25 | Komatsu Ltd. | High bearing-strength steel parts and processes for the production thereof |
| JPH11222627A (en) * | 1998-01-30 | 1999-08-17 | Komatsu Ltd | Rolling member and manufacturing method thereof |
| WO2012115135A1 (en) | 2011-02-23 | 2012-08-30 | Ｄｏｗａサーモテック株式会社 | Nitrided steel member and method for producing same |
| JP5301728B2 (en) * | 2010-03-30 | 2013-09-25 | アイシン・エィ・ダブリュ株式会社 | Gear and manufacturing method thereof |
| US9422613B2 (en) | 2012-01-26 | 2016-08-23 | Nippon Steel & Sumitomo Metal Corporation | Case hardened steel having reduced thermal treatment distortion |
| US9783879B2 (en) | 2012-04-18 | 2017-10-10 | Dowa Thermotech Co., Ltd. | Nitrided steel member and manufacturing method thereof |
| US11359271B2 (en) | 2015-03-31 | 2022-06-14 | Dowa Thermotech Co., Ltd. | Nitriding treatment method of steel member |
| CN117680729A (en) * | 2023-12-04 | 2024-03-12 | 东风汽车零部件(集团)有限公司刃量具分公司 | A method for drilling pin holes in the intermediate connection of double gears after heat treatment |
-
1991
- 1991-09-17 JP JP3236604A patent/JP2549039B2/en not_active Expired - Fee Related
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5746842A (en) * | 1995-09-29 | 1998-05-05 | Toa Steel Co., Ltd. | Steel gear |
| EP0769566A1 (en) | 1995-09-29 | 1997-04-23 | Toa Steel Co., Ltd. | Case hardening steel for gears |
| WO1998027242A1 (en) * | 1996-12-17 | 1998-06-25 | Komatsu Ltd. | High bearing-strength steel parts and processes for the production thereof |
| EP0950723A4 (en) * | 1996-12-17 | 2001-05-09 | Komatsu Mfg Co Ltd | High bearing-strength steel parts and processes for the production thereof |
| US6413328B2 (en) | 1996-12-17 | 2002-07-02 | Komatsu Ltd | High surface pressure resistant steel parts and methods of producing same |
| US6447619B1 (en) | 1996-12-17 | 2002-09-10 | Komatsu Ltd. | High surface pressure resistant steel parts and methods of producing same |
| EP1273672A1 (en) * | 1996-12-17 | 2003-01-08 | Komatsu Ltd. | High surface pressure resistant steel parts and methods of producing same |
| JPH11222627A (en) * | 1998-01-30 | 1999-08-17 | Komatsu Ltd | Rolling member and manufacturing method thereof |
| JP5301728B2 (en) * | 2010-03-30 | 2013-09-25 | アイシン・エィ・ダブリュ株式会社 | Gear and manufacturing method thereof |
| WO2012115135A1 (en) | 2011-02-23 | 2012-08-30 | Ｄｏｗａサーモテック株式会社 | Nitrided steel member and method for producing same |
| US9598760B2 (en) | 2011-02-23 | 2017-03-21 | Dowa Thermotech Co., Ltd. | Nitrided steel member and manufacturing method thereof |
| US9988704B2 (en) | 2011-02-23 | 2018-06-05 | Dowa Thermotech Co., Ltd. | Manufacturing method of nitrided steel member |
| US9422613B2 (en) | 2012-01-26 | 2016-08-23 | Nippon Steel & Sumitomo Metal Corporation | Case hardened steel having reduced thermal treatment distortion |
| US9783879B2 (en) | 2012-04-18 | 2017-10-10 | Dowa Thermotech Co., Ltd. | Nitrided steel member and manufacturing method thereof |
| US11359271B2 (en) | 2015-03-31 | 2022-06-14 | Dowa Thermotech Co., Ltd. | Nitriding treatment method of steel member |
| CN117680729A (en) * | 2023-12-04 | 2024-03-12 | 东风汽车零部件(集团)有限公司刃量具分公司 | A method for drilling pin holes in the intermediate connection of double gears after heat treatment |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2549039B2 (en) | 1996-10-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2548986B1 (en) | Steel for nitrocarburization and production method of a nitrocarburized steel part | |
| JP5099276B1 (en) | Gas carburized steel parts having excellent surface fatigue strength, steel for gas carburizing, and method for producing gas carburized steel parts | |
| JPH05148535A (en) | Production of surface hardened parts having decreased heat treating strain and excellent bending fatigue strength | |
| WO2006118243A1 (en) | Carburized induction-hardened component | |
| JP4354277B2 (en) | Method for manufacturing carburized and quenched members | |
| JPWO2014136307A1 (en) | Shaped material of induction-hardened parts and method for manufacturing the same | |
| JP2549039B2 (en) | Carbonitriding heat treatment method for high strength gears with small strain | |
| JPH11124653A (en) | Nitriding steel and nitriding method | |
| JP7524586B2 (en) | Case hardening steel, high strength member and manufacturing method thereof | |
| JP2549038B2 (en) | Method for carburizing heat treatment of high-strength gear with small strain and its gear | |
| JP2023144640A (en) | Nitriding steel and cold forging nitriding parts with excellent cold forging properties | |
| JPH08109435A (en) | Steel for low strain type carburized and quenched gear | |
| JP2002121645A (en) | Gear steel and gear with excellent root bending fatigue and surface pressure fatigue properties | |
| JP4737601B2 (en) | High temperature nitriding steel | |
| JPH0967644A (en) | Steel for carburized gears with excellent gear cutting performance | |
| JP7263796B2 (en) | RING GEAR FOR AUTOMOBILE TRANSMISSION AND MANUFACTURING METHOD THEREOF | |
| JP2006193827A (en) | Steel for soft nitriding and method for producing soft nitriding component | |
| JP7196707B2 (en) | Forged member for nitriding and its manufacturing method, and surface hardened forged member and its manufacturing method | |
| JP2019049032A (en) | Steel material for carburization processing | |
| JP2769136B2 (en) | Low distortion type steel material for carburized hardened gears | |
| JPH0227408B2 (en) | ||
| JP3109146B2 (en) | Manufacturing method of low strain high strength member | |
| JP6477614B2 (en) | Steel for soft nitriding and parts and method for manufacturing them | |
| JP2007107046A (en) | Induction hardening steel | |
| JPH07136863A (en) | Method for manufacturing austempered ductile cast iron gears |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 19960430 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080808 Year of fee payment: 12 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090808 Year of fee payment: 13 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090808 Year of fee payment: 13 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100808 Year of fee payment: 14 |
|
| LAPS | Cancellation because of no payment of annual fees |