JPH0757902B2 - Steel for carburizing gears with excellent fatigue strength - Google Patents
Steel for carburizing gears with excellent fatigue strengthInfo
- Publication number
- JPH0757902B2 JPH0757902B2 JP63134593A JP13459388A JPH0757902B2 JP H0757902 B2 JPH0757902 B2 JP H0757902B2 JP 63134593 A JP63134593 A JP 63134593A JP 13459388 A JP13459388 A JP 13459388A JP H0757902 B2 JPH0757902 B2 JP H0757902B2
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- Prior art keywords
- less
- steel
- fatigue strength
- carburizing
- gears
- 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.)
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- Gears, Cams (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は、疲労強度にすぐれる歯車用浸炭用鋼に関し、
詳しくは、自動車や産業機械等において、動力伝達系の
主要部品の一つとして、厳しい応力下に用いるに適する
疲労強度にすぐれる歯車を製造するための浸炭用鋼に関
する。Description: TECHNICAL FIELD The present invention relates to a steel for carburizing a gear having excellent fatigue strength,
More specifically, the present invention relates to carburizing steel for producing a gear having excellent fatigue strength suitable for use under severe stress as one of the main components of a power transmission system in automobiles, industrial machines and the like.
従来の技術 自動車や産業機械等における動力伝達系には、歯車が広
く用いられている。これら歯車は、その作動時、高速回
転下に高い応力が加えられる。従つて、従来、歯車の製
造においては、耐疲労性や耐摩耗性を向上させるため
に、肌焼鋼を用いて成形し、最終工程にて浸炭処理を施
して、表面硬さと圧縮残留応力を高くしている。しか
し、最近、例えば、自動車部品においては、エンジン性
能の向上と部品の小型化及び軽量化に伴つて、従来より
も一層疲労強度にすぐれる歯車が要求されるに至つてお
り、従来の肌焼鋼の用いる歯車では、かかる要求に応え
ることができない。2. Description of the Related Art Gears are widely used in power transmission systems in automobiles and industrial machines. During operation, these gears are highly stressed under high speed rotation. Therefore, conventionally, in the manufacture of gears, in order to improve fatigue resistance and wear resistance, it is formed using case-hardening steel and carburized in the final step to reduce surface hardness and compressive residual stress. It's high. However, recently, for example, in automobile parts, as the engine performance has been improved and the parts have been made smaller and lighter, a gear having better fatigue strength than ever has been required. Gears made of steel cannot meet such requirements.
発明が解決しようとする課題 そこで、本発明者らは、上記要求に応えるべく、歯車の
疲労破壊の機構を広範囲にわたつて研究した結果、疲労
破壊は、いずれの場合も、表面を起点として生じてお
り、また、表層部に深さ10〜20μｍであつて、硬さの著
しく低い不完全焼入れ層の生成が認められ、この不完全
焼入れ層が疲労強度に大きい影響を与えていることを見
出した。この不完全焼入れ層は、酸化異常層とも呼ばれ
ており、歯車の浸炭時に雰囲気ガスによつて表層部が粒
界に沿つて酸化され、SiやMn、Cr等の酸化物が形成さ
れ、焼入性に有効な固溶MnやCrの量が減少しており、そ
の結果として、焼入性が低くなつている。従つて、その
硬さは、内部に比べてHVにて200〜300程度も低い。DISCLOSURE OF INVENTION Problems to be Solved by the Invention Therefore, in order to meet the above requirements, the present inventors have extensively studied the mechanism of fatigue fracture of gears, and as a result, fatigue fracture occurs in any case starting from the surface. In addition, the formation of an incompletely hardened layer with a very low hardness was observed at a depth of 10 to 20 μm in the surface layer, and it was found that this incompletely hardened layer had a great influence on fatigue strength. It was This incompletely hardened layer is also called an abnormal oxidation layer, and when carburizing a gear, the surface layer is oxidized along the grain boundaries by the atmospheric gas, and oxides such as Si, Mn and Cr are formed, The amounts of solute Mn and Cr effective for hardenability are decreasing, and as a result, hardenability is low. Therefore, its hardness is about 200-300 lower at HV than inside.
また、このように、表層部に不完全焼入れ層が存在する
ときは、表層部における残留応力が圧縮残留応力より
は、引張残留応力となる。Further, when the incompletely hardened layer is present in the surface layer portion, the residual stress in the surface layer portion becomes a tensile residual stress rather than a compressive residual stress.
そこで、本発明者らは、歯車の疲労強度を高めるには、
上記のような浸炭焼入れ後の不完全焼入れ層の生成を防
止して、表面硬さと圧縮残留応力を高めることが必要で
あり、更に、疲労強度を一層高めるには、浸炭表層部に
オーステナイトを適正な量にて残留させることが有効で
あることを見出した。Therefore, the present inventors, in order to increase the fatigue strength of the gear,
It is necessary to prevent the formation of an incompletely hardened layer after carburizing and quenching as described above, and to increase the surface hardness and compressive residual stress.Furthermore, in order to further increase fatigue strength, austenite should be properly added to the carburized surface layer. It has been found that it is effective to leave a large amount.
本発明は、以上のような知見に基づいて完成されたもの
であつて、浸炭焼入れ後に、前記したような不完全焼入
れ層の生成を防止し得るように、最適の合金設計を行な
うと共に、Mo、Ｖ、Ｗ及びCuの添加量をそれらの間で適
正に調整して、オーステナイトの適正量を残留させるこ
とによつて、圧縮残留応力を高めることができ、かくし
て、疲労強度の高い歯車用浸炭用鋼を得て、本発明に至
つたものである。The present invention has been completed based on the above findings, and after carburizing and quenching, an optimal alloy design is performed so as to prevent the formation of an incompletely hardened layer as described above, and Mo , V, W, and Cu are appropriately adjusted among them to leave an appropriate amount of austenite, whereby compressive residual stress can be increased, and thus carburizing for gears having high fatigue strength. The present invention was achieved by obtaining steel for use.
従つて、本発明は、浸炭処理によつて、疲労強度にすぐ
れる歯車を与える歯車用浸炭用鋼を提供することを目的
とする。Therefore, it is an object of the present invention to provide a carburizing steel for gears that provides a gear with excellent fatigue strength by carburizing.
問題点を解決するための手段 本発明による疲労強度にすぐれる歯車用浸炭用鋼は、重
量％にて （ａ）Ｃ 0.10〜0.40％、 Si 0.15％以下、 Mn 0.30〜2.00％、 Cr 0.40〜2.00％、 Mo 0.30〜2.00％、 Ｐ 0.030％以下、 Ｓ 0.030％以下、 Cu 0.10％以下、及び Ｏ 0.0020％以下を含有し、更に、 （ｂ）Ca 0.010％以下、 Te 0.10％以下、 Zr 0.10％以下、及び REM 0.10％以下 よりなる群から選ばれる少なくとも１種の元素を含有
し、 残部鉄及び不可避的不純物よりなると共に、 ５≦−34（Cu％）＋16（Mo％）≦25 （式中、元素％は当該元素の鋼中の重量％による添加量
を示す。） を満足し、 且つ、硫化物系介在物の長さをｌ、幅をＷとするとき、
アスペクト比として規定されるl/Wが５以下であること
を特徴とする。Means for Solving the Problems The carburizing steel for gears having excellent fatigue strength according to the present invention is (a) C 0.10 to 0.40%, Si 0.15% or less, Mn 0.30 to 2.00%, Cr 0.40 to 2.00%, Mo 0.30 to 2.00%, P 0.030% or less, S 0.030% or less, Cu 0.10% or less, and O 0.0020% or less, and (b) Ca 0.010% or less, Te 0.10% or less, Zr 0.10. % Or less, and at least one element selected from the group consisting of REM 0.10% or less, the balance is iron and inevitable impurities, and 5 ≦ −34 (Cu%) + 16 (Mo%) ≦ 25 (formula In the above, the element% indicates the addition amount by the weight% of the element in the steel), and when the length of the sulfide inclusion is l and the width is W,
It is characterized in that the I / W defined as the aspect ratio is 5 or less.
以下に本発明について詳細に説明する。The present invention will be described in detail below.
Ｃは、強度を向上させるために少なくとも0.10％の添加
を必要とする。しかし、0.40％を越えて過多に添加する
ときは、切削性等の加工性を損なう。C requires at least 0.10% addition to improve strength. However, when it is added in excess of 0.40%, machinability such as machinability is impaired.
Siは、粒界酸化物を生成しやすい元素であつて、かかる
酸化物の生成は、粒界強度を低下させるので、添加量は
0.15％以下とする。Si is an element that easily forms a grain boundary oxide, and the formation of such an oxide lowers the grain boundary strength.
0.15% or less.
Mnも、粒界酸化物を生成しやすい元素であるが、焼入性
の向上による強度上昇、更には脱酸のために必要であ
る。本発明においては、上記脱酸のために少なくとも0.
30％を添加するが、過多に添加するときは切削性を劣化
させるので、添加量は2.0％以下とする。Mn is also an element that easily forms a grain boundary oxide, but it is necessary for increasing strength by improving hardenability and for deoxidizing. In the present invention, at least 0 is used for the deoxidation.
Although 30% is added, if too much is added, the machinability will deteriorate, so the amount added should be 2.0% or less.
Crも、Mnと同様に、粒界酸化物の生成傾向の強い元素で
あるが、同時に、焼入性を向上させる元素でもある。そ
こで、本発明においては、有効な焼入性向上の効果を得
るために、少なくとも0.40％を添加することとするが、
2.0％を越えて添加するときは、炭化物を生成し、更
に、粒界酸化物を生成して、焼入性を向上させる効果が
飽和する。Cr, like Mn, is an element that has a strong tendency to form grain boundary oxides, but is also an element that improves hardenability. Therefore, in the present invention, in order to obtain an effect of effectively improving the hardenability, at least 0.40% is added,
If it is added over 2.0%, carbides are formed, and further grain boundary oxides are formed, and the effect of improving hardenability is saturated.
Moは、粒界酸化物を生成し難く、浸炭表層部の焼入れ性
を確保し得る元素であり、更に、浸炭時の平衡炭素濃度
を上昇させる結果、焼入れ後に適当量の残留オーステナ
イトを生成させることによつて、高い疲労強度を得るこ
とができるので、本発明において最も重要な合金元素の
一つである。本発明においては、表層部の焼入性を改善
し、焼入れ後に適正量の残留オーステナイトを生成させ
るために、0.30％以上を添加することが必要であるが、
しかし、2.0％を越える過多量を添加しても、上記効果
が飽和すると共に、炭化物が著しく生成し、却つて疲労
強度を低下させることとなる。Mo is an element that does not easily generate grain boundary oxides and can secure the hardenability of the carburized surface layer. Furthermore, as a result of increasing the equilibrium carbon concentration during carburization, it is possible to generate an appropriate amount of retained austenite after quenching. This makes it possible to obtain high fatigue strength, and is one of the most important alloying elements in the present invention. In the present invention, to improve the hardenability of the surface layer portion, in order to generate an appropriate amount of retained austenite after quenching, it is necessary to add 0.30% or more,
However, even if an excessive amount exceeding 2.0% is added, the above effect is saturated, and carbides are remarkably formed, which rather reduces the fatigue strength.
Ｐは、その含有量が0.030％を越えるときは粒界強度を
低下させ、疲労強度の低下を招くので、本発明において
は、0.030％以下とする。When the content of P exceeds 0.030%, the grain boundary strength is lowered and the fatigue strength is lowered, so in the present invention, it is set to 0.030% or less.
Ｓも、その含有量が0.030％を越えるときは横目の強度
を低下させるので、0.030％以下とする。When S content is more than 0.030%, the strength of the cross grain is lowered, so it is set to 0.030% or less.
Cuは、Moとは反対に、浸炭時の平衡濃度を下げて、焼入
れ後に高い疲労強度を得るための適正量のオーステナイ
トを残留させる前記Moの効果を低減させる。従つて、本
発明においては、添加量の上限を0.10％とする。Contrary to Mo, Cu lowers the equilibrium concentration during carburization and reduces the effect of Mo that leaves an appropriate amount of austenite for obtaining high fatigue strength after quenching. Therefore, in the present invention, the upper limit of the added amount is 0.10%.
Ｏは、酸化物系介在物を生成して、疲労強度を低減させ
るので、製鋼上、可能な限りに少なくすることが望まし
く、本発明においては、0.0020％以下とする。O forms an oxide inclusion to reduce the fatigue strength, so it is desirable to reduce it as much as possible in terms of steelmaking, and in the present invention, it is 0.0020% or less.
本発明においては、上記した合金元素のうち、Cu及びMo
については、下記（１）式を満足させる必要がある。In the present invention, among the above alloy elements, Cu and Mo
For, it is necessary to satisfy the following formula (1).
５≦−34（Cu％）＋16（Mo％）≦25 （１） 即ち、Cu及びMoの添加量に上記関係を満足させることに
よつて、焼入れ後に高い疲労強度を得るに必要な適正な
残留オーステナイト量を確保することができる。本発明
においては、上記適正な残留オーステナイト量は、面積
率にて10〜40％であり、特に好ましくは20〜40％の範囲
である。上記式値が５よりも小さいときは、適正な残留
オーステナイト量を得ることができず、疲労強度を改善
するにあたつて、切欠き感受性を弱めることができな
い。他方、上記式値が25を越えるときは、高い圧縮残留
応力を得ることができないのみならず、高い表面硬さを
も得ることができない。5 ≦ −34 (Cu%) + 16 (Mo%) ≦ 25 (1) That is, by satisfying the above relations with the addition amounts of Cu and Mo, it is possible to obtain a suitable residual amount required to obtain high fatigue strength after quenching. The amount of austenite can be secured. In the present invention, the appropriate amount of retained austenite is 10 to 40% in area ratio, particularly preferably 20 to 40%. When the above formula value is smaller than 5, it is not possible to obtain a proper amount of retained austenite, and it is not possible to weaken notch sensitivity in improving fatigue strength. On the other hand, when the value of the above formula exceeds 25, not only high compressive residual stress cannot be obtained, but also high surface hardness cannot be obtained.
Caは、Ｓ又はMnSと結合することによつて、圧延、鍛造
によつて変形し難いCaS、Ca−MnSを生成して、横目の強
度低下を防止する効果を有する。かかる効果を有効に得
るためには、好ましくは、0.0003％以上が添加される。
しかし、過多量の添加は、Caの巨大な介在物を生成する
おそれがあるので、添加量は0.010％以下とする。Ca has the effect of forming CaS and Ca-MnS, which are difficult to deform by rolling and forging, by binding to S or MnS, and preventing the strength reduction of the cross grain. In order to effectively obtain such effects, 0.0003% or more is preferably added.
However, an excessive amount of addition may generate a large Ca inclusion, so the addition amount is set to 0.010% or less.
Teも、Caと同様に、Te−MnSの生成による硫化物の形態
制御を通じて、横目の強度低下を防止する効果を有し、
好ましくは0.005％以上が添加される。しかし、0.10％
を越えて添加しても、かかる効果が飽和する。Te, like Ca, also has the effect of preventing the reduction in the strength of the cross grain through morphology control of sulfide by the formation of Te-MnS,
Preferably 0.005% or more is added. But 0.10%
Even if added over the range, such an effect is saturated.
Zrも、Caと同様に、Zr−MnSを生成し、硫化物を形態制
御して、横目の強度低下を防止する効果を有し、好まし
くは0.005％以上が添加される。しかし、0.10％を越え
て添加しても、かかる効果が飽和する。Similar to Ca, Zr also has the effect of forming Zr-MnS and controlling the morphology of sulfides to prevent a decrease in the strength of the cross grain, and preferably 0.005% or more is added. However, even if added over 0.10%, such effect is saturated.
REMも同様に、硫化物の形態制御によつて、横目の強度
低下を防止する効果を有し、好ましくは0.005％以上が
添加される。しかし、0.10％を越えて添加しても、かか
る効果が飽和する。Similarly, REM also has the effect of preventing the decrease in the strength of the cross grain by controlling the morphology of the sulfide, and preferably 0.005% or more is added. However, even if added over 0.10%, such effect is saturated.
本発明による鋼は、上記硫化物形態制御元素によつて、
硫化物系介在物のアスペクト比、即ち、長さをｌ、幅を
Ｗとするとき、l/Wを５以下とすることが必要である。
歯車の疲労強度は、横目強度であるので、鋼中に紐状に
長く延びる硫化物系介在物が存在するときは、疲労強度
の劣化を招くからである。The steel according to the present invention, by the above sulfide morphology control element,
When the aspect ratio of the sulfide-based inclusions, that is, the length is 1 and the width is W, 1 / W must be 5 or less.
This is because the fatigue strength of the gear is a cross grain strength, so that when there is a sulfide-based inclusion that extends long like a cord in the steel, the fatigue strength deteriorates.
本発明による鋼は、上記した合金元素に加えて、 Ｖ 0.003〜0.20％、及び Ｗ 0.03〜1.0％ よりなる群から選ばれる少なくとも１種の元素を含有す
ることができる。The steel according to the present invention may contain at least one element selected from the group consisting of V 0.003 to 0.20% and W 0.03 to 1.0%, in addition to the above alloy elements.
Ｖ及びＷは、Moと同様に、浸炭時の平衡炭素濃度を上昇
させて、焼入れ後に、高い疲労強度を得ることを可能と
するオーステナイトの適正量を残留させる効果を有す
る。かかる効果を有効に得るためには、Ｖ及びＷのいず
れの元素についても、少なくとも0.03％を添加すること
が必要である。Ｖは、これを過多に添加するときは、結
晶粒を小さくさせ、残留オーステナイトの生成を阻害す
るので、添加量は0.20％以下とする。また、Ｗは、1.0
％を越えて添加しても、上記効果が飽和する。Similar to Mo, V and W have the effect of increasing the equilibrium carbon concentration during carburization and leaving an appropriate amount of austenite that makes it possible to obtain high fatigue strength after quenching. In order to effectively obtain such an effect, it is necessary to add at least 0.03% to each element of V and W. When V is added in an excessive amount, it reduces the crystal grains and inhibits the formation of retained austenite, so the addition amount is 0.20% or less. Also, W is 1.0
Even if added in excess of%, the above effect is saturated.
本発明において、鋼が上記のように、Ｖ及びＷよりなる
群から選ばれる少なくとも１種の元素を含有するとき
は、これら元素は、前述したCu及びMoと共に、下記
（２）式を満足させる必要がある。In the present invention, when the steel contains at least one element selected from the group consisting of V and W as described above, these elements, together with Cu and Mo described above, satisfy the following formula (2). There is a need.
５≦−34（Cu％）＋16（Mo％）＋５（Ｖ＋3W）≦25
（２） （式中、元素％は当該元素の鋼中の重量％による添加量
を示す。） 即ち、Cu、Mo、Ｖ及びＷの添加量に上記関係を満足させ
ることによつて、浸炭焼入れ後に表層部に高い疲労強度
を得るに必要が適正量の残留オーステナイトを確保する
ことができる。ここに、前述したように、適正な残留オ
ーステナイトは、面積率にて10〜40％であり、特に好ま
しくは20〜40％の範囲である。上記式値が５よりも小さ
いときは、適正な残留オーステナイトを得ることができ
ず、疲労強度を改善するにあたつて、切欠き感受性を弱
めることができない。他方、上記式値が25を越えるとき
は、高い圧縮残留応力を得ることができないのみなら
ず、高い表面硬さをも得ることができない。5 ≤ -34 (Cu%) + 16 (Mo%) + 5 (V + 3W) ≤ 25
(2) (In the formula, element% represents the amount of the element added by weight% in the steel.) That is, by satisfying the above relations in the amounts of Cu, Mo, V and W added, carburizing and quenching Later, it is possible to secure an appropriate amount of retained austenite necessary for obtaining high fatigue strength in the surface layer portion. Here, as described above, the appropriate retained austenite is in the range of 10 to 40%, and particularly preferably in the range of 20 to 40% in area ratio. When the above formula value is smaller than 5, it is impossible to obtain an appropriate retained austenite, and it is impossible to weaken the notch sensitivity in improving the fatigue strength. On the other hand, when the value of the above formula exceeds 25, not only high compressive residual stress cannot be obtained, but also high surface hardness cannot be obtained.
本発明による鋼は、常法に従つて、これを例えば鍛造
し、焼きならし処理し、浸炭焼入れ焼戻しすることによ
つて、疲労強度にすぐれる歯車を与える。The steel according to the present invention gives a gear having excellent fatigue strength by, for example, forging, normalizing, and carburizing and tempering according to a conventional method.
発明の効果 以上のように、本発明によれば、特に、高Mo量化と低Si
化を図ると共に、硫化物形態制御元素を加え、更に、Ｐ
及びＯ量を規制する合金設計によつて、浸炭後に、最表
層部の不完全焼入れ層の発生を防止して、表面硬さと表
面圧縮残留応力を高め、更に、オーステナイトの適正量
を残留させることによつて、疲労亀裂発生時の切欠き感
受性を弱めて、表面圧縮残留応力を一層高めることがで
き、かくして、疲労強度が格段に改善された歯車用浸炭
用鋼を得ることができる。Effects of the Invention As described above, according to the present invention, in particular, a high Mo content and a low Si content are achieved.
And the addition of sulfide morphology control elements,
And the alloy design that regulates the amount of O to prevent the occurrence of an incompletely hardened layer in the outermost surface layer after carburizing, increase the surface hardness and surface compressive residual stress, and further leave an appropriate amount of austenite. Thus, the notch sensitivity at the time of fatigue cracking can be weakened and the surface compressive residual stress can be further enhanced, and thus, carburizing steel for gears with significantly improved fatigue strength can be obtained.
実施例 以下に実施例を挙げて本発明を説明するが、本発明はこ
れら実施例により何ら限定されるものではない。EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
第１表に発明鋼１〜４及び比較鋼１〜４の化学成分を示
す。これら供試鋼を鍛造した後、焼きならし処理し、試
験片に加工し、次いで、925℃で３時間、カーボンポテ
ンシヤル0.80％の条件下にて浸炭処理し、次いで850℃
に炉冷し、30分間保持し、油冷して焼入れした後、180
℃にて２時間加熱し、空冷して、焼戻し処理した。Table 1 shows the chemical composition of the invention steels 1 to 4 and the comparative steels 1 to 4. After forging these test steels, they are normalized, processed into test pieces, then carburized at 925 ° C for 3 hours under conditions of carbon potential 0.80%, and then at 850 ° C.
Furnace, hold for 30 minutes, oil cool and quench, then
It heated at 2 degreeC for 2 hours, air-cooled, and tempered.
このように浸炭焼入れ焼戻し処理した試験片の浸炭特性
を第２表に示し、回転曲げ疲労試験結果 及び歯車疲労試験結果を第３表に示す。回転曲げ疲労試
験は、平行部8mmの平滑試験片を用いて、回転数3600rpm
にて行なつた。また、歯車疲労試験は、歯数38枚、モジ
ユール1.5の歯車について、動力循環式歯車疲労試験機
を用いて、回転数3000rpmにて行なつた。Table 2 shows the carburizing characteristics of the specimens carburized, quenched and tempered in this way. Table 3 shows the gear fatigue test results. The rotating bending fatigue test uses a smooth test piece with a parallel part of 8 mm and rotates at 3600 rpm.
I went to. Further, the gear fatigue test was carried out on a gear having 38 teeth and a module of 1.5 using a power circulation type gear fatigue tester at a rotation speed of 3000 rpm.
本発明鋼によれば、浸炭焼入れ後に、最表層部に不完全
焼入れ層の発生がないか、又はあつても極めて僅かであ
り，かくして、高い表面硬さと表面圧縮残留応力とを有
し、且つ、表層部に適正量の残留オーステナイトが存在
して、疲労強度にすぐれる歯車を得ることができる。 According to the steel of the present invention, after carburizing and quenching, there is no occurrence of an incompletely-quenched layer in the outermost surface layer, or at least it is extremely small, thus having high surface hardness and surface compressive residual stress, and Since a proper amount of retained austenite is present in the surface layer, it is possible to obtain a gear having excellent fatigue strength.
Claims (2)
し、 残部鉄及び不可避的不純物よりなると共に、 ５≦−34（Cu％）＋16（Mo％）≦25 （式中、元素％は当該元素の鋼中の重量％による添加量
を示す。） を満足し、 且つ、硫化物系介在物の長さをｌ、幅をＷとするとき、
アスペクト比として規定されるl/Wが５以下であること
を特徴とする疲労強度にすぐれる歯車用浸炭用鋼。1. By weight% (a) C 0.10 to 0.40%, Si 0.15% or less, Mn 0.30 to 2.00%, Cr 0.40 to 2.00%, Mo 0.30 to 2.00%, P 0.030% or less, S 0.030% or less , Cu 0.10% or less, and O 0.0020% or less, and (b) at least one selected from the group consisting of Ca 0.010% or less, Te 0.10% or less, Zr 0.10% or less, and REM 0.10% or less. Containing the element, consisting of the balance iron and unavoidable impurities, and 5 ≦ −34 (Cu%) + 16 (Mo%) ≦ 25 (in the formula, the element% indicates the addition amount by weight% of the element in the steel. .) And the length of the sulfide inclusion is l and the width is W,
A steel for carburizing gears with excellent fatigue strength, characterized in that the I / W defined as the aspect ratio is 5 or less.
し、 残部鉄及び不可避的不純物よりなると共に、 ５≦−34（Cu％）＋16（Mo％）＋５（Ｖ＋3W）≦25 （式中、元素％は当該元素の鋼中の重量％による添加量
を示す。） を満足し、 且つ、硫化物系介在物の長さをｌ、幅をＷとするとき、
アスペクト比として規定されるl/Wが５以下であること
を特徴とする疲労強度にすぐれる歯車用浸炭用鋼。2. In% by weight (a) C 0.10 to 0.40%, Si 0.15% or less, Mn 0.30 to 2.00%, Cr 0.40 to 2.00%, Mo 0.30 to 2.00%, P 0.030% or less, S 0.030% or less , Cu 0.10% or less, and O 0.0020% or less, and (b) at least one selected from the group consisting of Ca 0.010% or less, Te 0.10% or less, Zr 0.10% or less, and REM 0.10% or less. An element and (c) at least one element selected from the group consisting of V 0.03 to 0.20% and W 0.03 to 1.0%, the balance being iron and inevitable impurities, and 5 ≦ −34 (Cu %) + 16 (Mo%) + 5 (V + 3W) ≦ 25 (in the formula, element% indicates the amount of the element added by weight% in steel.) And the length of the sulfide inclusions is l and width is W,
A steel for carburizing gears with excellent fatigue strength, characterized in that the I / W defined as the aspect ratio is 5 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63134593A JPH0757902B2 (en) | 1988-05-31 | 1988-05-31 | Steel for carburizing gears with excellent fatigue strength |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63134593A JPH0757902B2 (en) | 1988-05-31 | 1988-05-31 | Steel for carburizing gears with excellent fatigue strength |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01306545A JPH01306545A (en) | 1989-12-11 |
| JPH0757902B2 true JPH0757902B2 (en) | 1995-06-21 |
Family
ID=15132014
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63134593A Expired - Lifetime JPH0757902B2 (en) | 1988-05-31 | 1988-05-31 | Steel for carburizing gears with excellent fatigue strength |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0757902B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05148535A (en) * | 1991-06-07 | 1993-06-15 | Kobe Steel Ltd | Production of surface hardened parts having decreased heat treating strain and excellent bending fatigue strength |
| KR20010054261A (en) * | 1999-12-04 | 2001-07-02 | 이계안 | Alloy for transmission gear |
| CN104561806B (en) * | 2015-02-10 | 2016-08-31 | 苏州劲元油压机械有限公司 | A kind of steel plate for shelf load-bearing and processing technique thereof |
-
1988
- 1988-05-31 JP JP63134593A patent/JPH0757902B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01306545A (en) | 1989-12-11 |
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