JP2001329337A - Case hardening steel excellent in chipping resistance - Google Patents

Case hardening steel excellent in chipping resistance

Info

Publication number
JP2001329337A
JP2001329337A JP2000145586A JP2000145586A JP2001329337A JP 2001329337 A JP2001329337 A JP 2001329337A JP 2000145586 A JP2000145586 A JP 2000145586A JP 2000145586 A JP2000145586 A JP 2000145586A JP 2001329337 A JP2001329337 A JP 2001329337A
Authority
JP
Japan
Prior art keywords
steel
case hardening
resistance
carburizing
hardening steel
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
Application number
JP2000145586A
Other languages
Japanese (ja)
Other versions
JP3883782B2 (en
Inventor
Toru Nagaoka
亨 長岡
Hiroshi Nishimori
博 西森
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sanyo Special Steel Co Ltd
Original Assignee
Sanyo Special Steel Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Sanyo Special Steel Co Ltd filed Critical Sanyo Special Steel Co Ltd
Priority to JP2000145586A priority Critical patent/JP3883782B2/en
Publication of JP2001329337A publication Critical patent/JP2001329337A/en
Application granted granted Critical
Publication of JP3883782B2 publication Critical patent/JP3883782B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Abstract

PROBLEM TO BE SOLVED: To provide case hardening steel for carburizing or carbo-nitriding capable of obtaining carburized parts excellent in chipping resistance. SOLUTION: In this case hardening steel excellent in chipping resistance shown in the figure, fine TiC is dispersed into steel by the addition of Ti to dispersedly reinforce the matrix of the steel, also, 4Si+Mn+2Cr>4.3 is satisfied to improve its softening resistance, and further, the content of Si is controlled to 0.40 to 1.50% to reduce the depth of an intergranular oxidized layer in the surface layer formed at the time of carburizing or carbo-nitriding compared to that in JIS SCM420 of Si: 0.15 to 0.35%.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は、耐ピッチング性に
優れた浸炭部品を得る浸炭又は浸炭窒化用の鋼に関す
る。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel for carburizing or carbonitriding for obtaining a carburized part having excellent pitting resistance.

【0002】[0002]

【従来の技術】これまで機械構造部品である歯車やシャ
フト等の歯車用鋼として、JIS SCr420、SC
M420に代表される肌焼鋼が用いられてきたものの、
歯車の高強度化の要求はますます高まっており、特にピ
ッチング寿命の向上が望まれている。ピッチング寿命向
上のためには、特開平7−258793号公報に述べら
れているようにSiの増量添加によって、耐軟化性の向
上と同時に粒界酸化層深さを低減することは有効と考え
られる。しかしながら、ピッチング寿命の長寿命化はま
だ不十分であるのが現状である。
2. Description of the Related Art Hitherto, JIS SCr420 and SC have been used as gear steel such as gears and shafts which are mechanical structural parts.
Although case hardening steel represented by M420 has been used,
There is an increasing demand for higher strength gears, and in particular, it is desired to improve the pitching life. In order to improve the pitting life, it is considered effective to increase the softening resistance and simultaneously reduce the grain boundary oxide layer depth by increasing the amount of Si as described in JP-A-7-258793. . However, at present, the extension of the pitching life is still insufficient.

【0003】[0003]

【発明が解決しようとする課題】本発明は、上記のよう
な事情を背景としてなされたもので、本発明の目的とす
るところは、耐ピッチング性に優れる肌焼鋼を提供する
ことにある。
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a case hardening steel having excellent pitting resistance.

【0004】[0004]

【課題を解決するための手段】耐ピッチング性向上のた
めには、耐軟化性の向上と同時に粒界酸化層深さを低減
する必要がある。そのために、本発明では、Ti添加に
より微細なTiCを鋼中に分散させ、鋼マトリックスの
分散強化を図り、かつ4Si+Mn+2Cr>4.3を
満たすことにより耐軟化性を向上させ、さらにSi含有
量を0.40〜1.50%とし、浸炭もしくは浸炭窒化
時に生成する表面層の粒界酸化層深さがSi:0.15
〜0.35%のJIS SCM420に比して低減させ
得ることを特徴とする。
In order to improve the pitting resistance, it is necessary to reduce the depth of the grain boundary oxide layer at the same time as improving the softening resistance. Therefore, in the present invention, fine TiC is dispersed in the steel by adding Ti, the dispersion strengthening of the steel matrix is achieved, and the softening resistance is improved by satisfying 4Si + Mn + 2Cr> 4.3, and the Si content is further reduced. 0.40 to 1.50%, and the grain boundary oxide layer depth of the surface layer generated during carburizing or carbonitriding is Si: 0.15
It is characterized in that it can be reduced compared to JIS SCM420 of 〜0.35%.

【0005】すなわち、上記の課題を解決するための本
発明の手段は、請求項1の発明では、合金元素の含有率
が、質量%で、C:0.10〜0.35%、Si:0.
40〜1.50%、Mn:0.30〜2.00%、P:
≦0.030%、S:≦0.030%、Cr:0.50
〜3.00%、Ti:0.02〜0.20%を含有し、
残部がFe及び不可避不純物からなり、鋼中に微細なT
iCを分散させ、鋼マトリックスの分散強化を図り、か
つ4Si+Mn+2Cr>4.3を満たすことにより耐
軟化性を向上させ、浸炭もしくは浸炭窒化時に生成する
表面層の粒界酸化層深さがJIS SCM420に比し
て低減させ得ることを特徴とする耐ピッチング性に優れ
た肌焼鋼である。
[0005] That is, the means of the present invention for solving the above-mentioned problems is that, in the invention of claim 1, the content of the alloy element is 0.10 to 0.35% by mass, C: 0.10 to 0.35%, 0.
40-1.50%, Mn: 0.30-2.00%, P:
0.030%, S: 0.030%, Cr: 0.50
33.00%, Ti: 0.02 to 0.20%,
The balance consists of Fe and unavoidable impurities, and the fine T
By dispersing iC, strengthening the dispersion of the steel matrix, and improving the softening resistance by satisfying 4Si + Mn + 2Cr> 4.3, the grain boundary oxide layer depth of the surface layer generated during carburizing or carbonitriding is reduced to JIS SCM420. It is a case hardening steel excellent in pitting resistance, characterized in that it can be reduced in comparison.

【0006】請求項2の発明では、請求項1の手段の合
金元素に加えて、質量%で、Mo:≦1.50%、N
i:≦3.50%、Nb:≦0.20%、V:≦0.5
0%のうち、1種又は2種以上を含有し、残部がFe及
び不可避不純物からなり、鋼中に微細なTiCを分散さ
せ、鋼マトリックスの分散強化を図り、かつ4Si+M
n+2Cr>4.3を満たすことにより耐軟化性を向上
させ、浸炭もしくは浸炭窒化時に生成する表面層の粒界
酸化層深さがJIS SCM420に比して低減させ得
ることを特徴とする耐ピッチング性に優れた肌焼鋼であ
る。
According to a second aspect of the present invention, in addition to the alloy element of the first aspect, Mo: ≦ 1.50%, N
i: ≦ 3.50%, Nb: ≦ 0.20%, V: ≦ 0.5
0%, one or more of them are contained, and the balance consists of Fe and unavoidable impurities, disperses fine TiC in the steel, strengthens the dispersion of the steel matrix, and adds 4Si + M
Pitching resistance characterized by improving softening resistance by satisfying n + 2Cr> 4.3 and reducing the grain boundary oxide layer depth of the surface layer generated during carburizing or carbonitriding as compared with JIS SCM420. Excellent case hardening steel.

【0007】合金元素の限定理由を以下に説明する。な
お、質量%で示す。
The reasons for limiting the alloying elements will be described below. In addition, it shows by mass%.

【0008】C:0.10〜0.35% Cは、鋼の強度を確保するために必須の元素であり、そ
の含有量が浸炭焼入焼戻し後の心部硬さを決定する。そ
こで、本発明ではC量の下限を0.10%とし、心部の
硬さを確保している。しかし、その含有量が多すぎると
靱性が劣化や被削性を低下させるなどの弊害をもたらす
ので、C含有量の上限を0.35%とする。
C: 0.10 to 0.35% C is an essential element for ensuring the strength of steel, and its content determines the core hardness after carburizing, quenching and tempering. Therefore, in the present invention, the lower limit of the C content is set to 0.10%, and the hardness of the core is secured. However, if the content is too large, it causes adverse effects such as deterioration of toughness and deterioration of machinability, so the upper limit of the C content is set to 0.35%.

【0009】Si:0.40〜1.50% Siは、本発明において重要な役割を持つ元素であっ
て、浸炭あるいは浸炭窒化後に表面に生成する粒界酸化
層深さを低減し、かつ同時に焼戻軟化抵抗性を向上させ
るために添加する。この効果を得るためには0.40%
以上含有する必要があるが、多すぎると靱性を阻害する
ので上限を1.50%とする。
Si: 0.40 to 1.50% Si is an element having an important role in the present invention, and reduces the depth of the grain boundary oxide layer formed on the surface after carburizing or carbonitriding, and at the same time, It is added to improve temper softening resistance. 0.40% to achieve this effect
It is necessary to contain the above, but if too much, the toughness is impaired, so the upper limit is made 1.50%.

【0010】Mn:0.30〜2.00% Mnは、焼戻軟化抵抗性を向上させる元素であるために
添加され、その効果を得るためには、0.30%以上を
必要とする。しかし、過剰に添加すると素材の軟化焼き
なましを困難とし、また被削性や冷鍛性を劣化させるう
え、耐ピッチング性が飽和するため、その上限を2.0
0%とする。
Mn: 0.30 to 2.00% Mn is added because it is an element for improving temper softening resistance, and to obtain the effect, Mn needs to be 0.30% or more. However, if added excessively, it becomes difficult to soften and anneal the material, and the machinability and cold forgeability are deteriorated, and the pitting resistance is saturated.
0%.

【0011】P:≦0.030% Pは、オーステナイト粒界に偏析して靱性を低下させる
ため、含有量の上限を0.030%とする。
P: ≦ 0.030% Since P segregates at austenite grain boundaries and lowers toughness, the upper limit of the content is made 0.030%.

【0012】S:≦0.030% Sは、熱間加工性を害し、また鋼中でMnSなる非金属
介在物を形成して、横方向の靱性を損なうので、その上
限を0.030%とする。
S: ≦ 0.030% S impairs hot workability and forms non-metallic inclusions of MnS in steel to impair the toughness in the transverse direction. And

【0013】Cr:0.50〜3.00% Crは、焼入性の向上に寄与するとともに、焼戻軟化抵
抗性を増大させて耐ピッチング性を向上させるのに寄与
する元素であり、このような効果を得るために、0.5
0%以上とする。しかし、3.00%を超えて添加して
も耐ピッチング性向上の効果は飽和し、かえって被削性
を劣化させるので3.00%以下とする。
Cr: 0.50 to 3.00% Cr is an element that contributes to the improvement of hardenability and also to the improvement of pitting resistance by increasing temper softening resistance. 0.5
0% or more. However, even if added in excess of 3.00%, the effect of improving the pitting resistance is saturated and the machinability is rather deteriorated.

【0014】Ti:0.02〜0.20% Tiは、TiCとして鋼中に微細に析出することによ
り、鋼マトリックスを分散強化し、ピッチングに至るき
裂の生成、伝播を遅延させる元素であり、このような効
果を得るために、0.02%以上とする。。しかし、
0.20%を超えて添加すると、被削性を劣化させるの
で、上限を0.20%とする。
Ti: 0.02 to 0.20% Ti is an element that precipitates finely as TiC in steel, thereby dispersing and strengthening the steel matrix and delaying the generation and propagation of cracks leading to pitting. In order to obtain such an effect, the content is made 0.02% or more. . But,
If added in excess of 0.20%, machinability deteriorates, so the upper limit is made 0.20%.

【0015】4Si+Mn+2Cr>4.3 上記式を満たすSi、Mn、Crの複合添加により、3
00℃にて測定した高温硬さがJIS SCM420相
当鋼に比し、HV≧530となり、ピッチング寿命が延
長される。
4Si + Mn + 2Cr> 4.3 By the combined addition of Si, Mn and Cr satisfying the above formula, 3
The high-temperature hardness measured at 00 ° C. becomes HV ≧ 530 as compared with JIS SCM420 equivalent steel, and the pitting life is extended.

【0016】Mo:≦1.50% Moは、焼入性の向上に寄与するとともに、鋼の靱性を
向上させるので、焼入性と靱性を確保するため任意に添
加することができる。しかし、1.50%を超えて添加
すると素材の軟化焼きなましを困難とし、被削性や冷鍛
性を劣化させるため1.50%以下とする。
Mo: ≤ 1.50% Mo contributes to the improvement of hardenability and also improves the toughness of steel. Therefore, Mo can be arbitrarily added to secure hardenability and toughness. However, if it is added in excess of 1.50%, it becomes difficult to soften and anneal the material, and the machinability and cold forgeability are deteriorated.

【0017】Ni:≦3.50% Niは、鋼に所定の焼入性を付与するとともに、鋼の靱
性を向上させるので、焼入性と靱性を確保するため任意
に添加することができる。しかし、3.50%を超えて
含有させても、その効果は飽和し経済性を損なうので
3.50%を上限とする。
Ni: ≤3.50% Ni imparts a predetermined hardenability to the steel and improves the toughness of the steel. Ni can be optionally added to secure the hardenability and the toughness. However, if the content exceeds 3.50%, the effect is saturated and the economy is impaired, so the upper limit is 3.50%.

【0018】Nb:≦0.20% V:≦0.50% Nb、Vは、いずれも微細な炭化物あるいは炭窒化物を
形成し、浸炭あるいは浸炭窒化処理時の結晶粒微細化に
寄与して機械構造部材の靱性を高めるのに有効な元素で
あるので、必要に応じてこれらの1種または2種を適宜
添加し、オーステナイト結晶粒を微細化する。しかしな
がら、添加量が多すぎても微細効果は飽和し、かえって
機械的性質を劣化させることもあるため、Nbについて
は0.20%以下、Vについては0.50%以下とす
る。
Nb: ≦ 0.20% V: ≦ 0.50% Both Nb and V form fine carbides or carbonitrides and contribute to the refinement of crystal grains during carburizing or carbonitriding. Since it is an element effective for increasing the toughness of the mechanical structural member, one or two of these elements are appropriately added as necessary to refine the austenite crystal grains. However, if the added amount is too large, the fine effect is saturated and the mechanical properties may be deteriorated. Therefore, Nb is set to 0.20% or less, and V is set to 0.50% or less.

【0019】[0019]

【発明の実施の形態】本発明の実施の形態の鋼について
表1および以下の表並びに実施例を通じて示す。表1に
おいて、鋼種C、鋼種D、鋼種E、鋼種F、鋼種Hは請
求項1の発明の実施の形態である。鋼種A、鋼種B、鋼
種G、鋼種I、鋼種Jは請求項2の発明の実施の形態で
ある。
BEST MODE FOR CARRYING OUT THE INVENTION Steel according to an embodiment of the present invention is shown in Table 1 and the following tables and examples. In Table 1, steel type C, steel type D, steel type E, steel type F, and steel type H are embodiments of the first aspect of the present invention. Steel type A, steel type B, steel type G, steel type I, and steel type J are an embodiment of the second aspect of the present invention.

【0020】[0020]

【表1】 [Table 1]

【0021】[0021]

【実施例】表1示す化学組成の鋼を100kg真空溶解
炉で溶製した後、1200℃の熱間鍛造によって直径3
2mmの素材を製造した。次いで、前記各素材に対して
焼きならしを施した後、図1に示すローラーピッチング
試験片1を作成した。このローラーピッチング試験片1
は、中央の大径部の直径が26mm、長さが28mmで
あり、両側の小径部の直径が22mm、長さが51mm
の寸法を有するものである。そして、各ローラーピッチ
ング試験片1に対して後記する浸炭あるいは浸炭窒化処
理を施した後、ローラーピッチング試験を行った。
EXAMPLE 100 kg of steel having the chemical composition shown in Table 1 was melted in a vacuum melting furnace, and then hot forged at 1200 ° C. to obtain a diameter of 3 mm.
A 2 mm blank was produced. Next, after normalizing each of the materials, a roller pitching test piece 1 shown in FIG. 1 was prepared. This roller pitching test piece 1
Has a central large-diameter portion having a diameter of 26 mm and a length of 28 mm, and small-diameter portions on both sides having a diameter of 22 mm and a length of 51 mm.
Having the following dimensions. Then, after performing the carburizing or carbonitriding treatment described below on each roller pitting test piece 1, a roller pitting test was performed.

【0022】ここで、ローラーピッチング試験の原理を
図2に示す。すなわち、ローラーピッチング試験片1
(小ローラー:材質は表1の鋼種A〜N)と相手材2
(大ローラー:JIS SCM420相当)とを340
kgf/mm2すなわち、3334N/mm2の面圧下で
高速回転させ、ピッチングが発生するまでの寿命である
回転数を求めて耐ピッチング性を評価した。なお、この
場合、ローラーピッチング試験片1(小ローラー)と相
手材2(大ローラー)との周速の差、すなわちすべり率
は40%である。そして、各条件についてそれぞれ5本
のローラーピッチング試験片1を対象として試験を行っ
た後、ワイブルプロットを行ない、50%破損確率寿命
(B50寿命)を求めて耐ピッチング性を評価した。ま
た、表面部に生成する粒界酸化層を光学顕微鏡により観
察し、その深さを測定した。さらに、表面硬化層断面の
表面から80μm位置における硬さを300℃の高温条
件下にて測定した。浸炭処理材の結果を表2ならびに図
3、浸炭窒化処理材の結果を表3ならびに図4に示す。
Here, the principle of the roller pitching test is shown in FIG. That is, the roller pitching test piece 1
(Small roller: Material is steel type A to N in Table 1) and counterpart material 2
(Large roller: JIS SCM420 equivalent) and 340
It was rotated at a high speed under a surface pressure of kgf / mm 2, that is, 3334 N / mm 2 , and the number of rotations, which is the life until pitting occurred, was determined to evaluate the pitting resistance. In this case, the difference in peripheral speed between the roller pitching test piece 1 (small roller) and the counterpart material 2 (large roller), that is, the slip ratio is 40%. Then, after performing a test on each of the five roller pitching test pieces 1 under each condition, a Weibull plot was performed, and a 50% failure probability life ( B50 life) was obtained to evaluate pitting resistance. The grain boundary oxide layer formed on the surface was observed with an optical microscope, and the depth was measured. Furthermore, the hardness at a position of 80 μm from the surface of the cross section of the surface hardened layer was measured under a high temperature condition of 300 ° C. The results of the carburized material are shown in Table 2 and FIG. 3, and the results of the carbonitrided material are shown in Table 3 and FIG.

【0023】[0023]

【表2】 [Table 2]

【0024】さらに、各ローラーピッチング試験片1に
対する浸炭処理は、各試験片1を930℃で6時間保持
している間に浸炭を行ない、830℃で30分保持した
後、60℃の油槽に投入して焼入れし、170℃で90
分の焼戻しを行った。浸炭窒化処理は各試験片1を93
0℃で6時間保持している間に浸炭を行ない830℃に
冷却保持する過程でNH3を流すことによって窒化を行
った。その後、60℃の油槽に投入して焼入れした後、
170℃で90分の焼戻しを行った。
Further, the carburizing treatment for each roller pitching test piece 1 is performed by carburizing while holding each test piece 1 at 930 ° C. for 6 hours, holding at 830 ° C. for 30 minutes, and then placing the test piece in a 60 ° C. oil bath. And quenched at 170 ° C for 90
Tempering was performed. In the carbonitriding treatment, 93
Nitriding was carried out by flowing NH 3 during the process of carburizing while maintaining the temperature at 0 ° C. for 6 hours and cooling and maintaining the temperature at 830 ° C. After that, after quenching by putting it in a 60 ° C oil bath,
Tempering was performed at 170 ° C. for 90 minutes.

【0025】[0025]

【表3】 [Table 3]

【0026】[0026]

【発明の効果】以上説明したとおり、本発明鋼は、鋼中
に微細なTiCを分散させて鋼マトリックスを分散強化
し、かつ、鋼の化学成分のSi、Mn、Crの関係を4
Si+Mn+2Cr>4.3とすることで、耐軟化性を
向上させ、さらにSiを0.40〜1.50質量%と高
めることで、耐ピッチング性に優れた特性を有する肌焼
鋼を得ることができる。
As described above, in the steel of the present invention, fine TiC is dispersed in the steel to disperse and strengthen the steel matrix, and the relationship between the chemical components of the steel, Si, Mn, and Cr, is 4%.
By setting Si + Mn + 2Cr> 4.3, softening resistance is improved, and by further increasing Si to 0.40 to 1.50 mass%, a case hardening steel having excellent pitting resistance can be obtained. it can.

【図面の簡単な説明】[Brief description of the drawings]

【図1】ローラーピッチング試験片の概略を示す側面図
である。
FIG. 1 is a side view schematically showing a roller pitching test piece.

【図2】ローラーピッチング試験の原理を示す斜視図で
ある。
FIG. 2 is a perspective view showing the principle of a roller pitching test.

【図3】4Si+Mn+2Crの値とピッチング寿命関
係で、浸炭材のローラーピッチング試験結果を示すグラ
フである。
FIG. 3 is a graph showing the results of a roller pitting test of a carburized material in relation to the value of 4Si + Mn + 2Cr and the pitting life.

【図4】4Si+Mn+2Crの値とピッチング寿命関
係で、浸炭窒化材のローラーピッチング試験結果を示す
グラフである。
FIG. 4 is a graph showing a roller pitting test result of a carbonitrided material in relation to a value of 4Si + Mn + 2Cr and a pitting life.

【符号の説明】[Explanation of symbols]

1 ローラーピッチング試験片 2 相手材 1 Roller pitching test piece 2 Counterpart material

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】 合金元素の含有率が、質量%で、C:
0.10〜0.35%、Si:0.40〜1.50%、
Mn:0.30〜2.00%、P:≦0.030%、
S:≦0.030%、Cr:0.50〜3.00%、T
i:0.02〜0.20%を含有し、残部がFe及び不
可避不純物からなり、鋼中に微細なTiCを分散させ、
鋼マトリックスの分散強化を図り、かつ4Si+Mn+
2Cr>4.3を満たすことにより耐軟化性を向上さ
せ、浸炭もしくは浸炭窒化時に生成する表面層の粒界酸
化層深さがJIS SCM420に比して低減させ得る
ことを特徴とする耐ピッチング性に優れた肌焼鋼。
1. The method according to claim 1, wherein the content of the alloy element is C:
0.10 to 0.35%, Si: 0.40 to 1.50%,
Mn: 0.30 to 2.00%, P: ≦ 0.030%,
S: ≦ 0.030%, Cr: 0.50 to 3.00%, T
i: containing 0.02 to 0.20%, the balance being Fe and unavoidable impurities, dispersing fine TiC in steel,
Dispersion strengthening of steel matrix and 4Si + Mn +
By satisfying 2Cr> 4.3, the softening resistance is improved, and the grain boundary oxide layer depth of the surface layer generated during carburizing or carbonitriding can be reduced as compared with JIS SCM420. Excellent case hardening steel.
【請求項2】 請求項1記載の合金元素に加えて、質量
%で、Mo:≦1.50%、Ni:≦3.50%、N
b:≦0.20%、V:≦0.50%のうち、1種又は
2種以上を含有し、残部がFe及び不可避不純物からな
り、鋼中に微細なTiCを分散させ、鋼マトリックスの
分散強化を図り、かつ4Si+Mn+2Cr>4.3を
満たすことにより耐軟化性を向上させ、浸炭もしくは浸
炭窒化時に生成する表面層の粒界酸化層深さがJIS
SCM420に比して低減させ得ることを特徴とする耐
ピッチング性に優れた肌焼鋼。
2. In addition to the alloy elements according to claim 1, Mo: ≦ 1.50%, Ni: ≦ 3.50%, N
b: ≦ 0.20%, V: ≦ 0.50%, containing one or more kinds, the balance being Fe and unavoidable impurities, dispersing fine TiC in the steel, By strengthening the dispersion and satisfying 4Si + Mn + 2Cr> 4.3, the softening resistance is improved, and the grain boundary oxide layer depth of the surface layer formed during carburizing or carbonitriding is JIS.
A case hardening steel having excellent pitting resistance, which can be reduced as compared with SCM420.
JP2000145586A 2000-05-17 2000-05-17 Case-hardened steel with excellent pitting resistance Expired - Fee Related JP3883782B2 (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009034970A1 (en) * 2007-09-12 2009-03-19 Sanyo Special Steel Co., Ltd. Case-hardening steel being excellent in contact pressure fatigue strength, impact strength and bending fatigue strength
WO2011132722A1 (en) 2010-04-19 2011-10-27 新日本製鐵株式会社 Steel component having excellent temper softening resistance
DE102005061946B4 (en) * 2004-12-27 2013-03-21 Nippon Steel Corp. Case hardened steel having excellent tooth surface fatigue strength, gear using the same, and methods of making same
CN104894506A (en) * 2015-06-24 2015-09-09 南车戚墅堰机车车辆工艺研究所有限公司 Automobile transmission gear heat treatment method

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS621843A (en) * 1985-06-25 1987-01-07 Nissan Motor Co Ltd High toughness carburizing steel
JPH11201168A (en) * 1998-01-12 1999-07-27 Nippon Seiko Kk Rolling bearing

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS621843A (en) * 1985-06-25 1987-01-07 Nissan Motor Co Ltd High toughness carburizing steel
JPH11201168A (en) * 1998-01-12 1999-07-27 Nippon Seiko Kk Rolling bearing

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005061946B4 (en) * 2004-12-27 2013-03-21 Nippon Steel Corp. Case hardened steel having excellent tooth surface fatigue strength, gear using the same, and methods of making same
WO2009034970A1 (en) * 2007-09-12 2009-03-19 Sanyo Special Steel Co., Ltd. Case-hardening steel being excellent in contact pressure fatigue strength, impact strength and bending fatigue strength
JP2009068064A (en) * 2007-09-12 2009-04-02 Sanyo Special Steel Co Ltd Case hardening steel excellent in bearing fatigue-strength, impact-strength and bending fatigue-strength
WO2011132722A1 (en) 2010-04-19 2011-10-27 新日本製鐵株式会社 Steel component having excellent temper softening resistance
CN104894506A (en) * 2015-06-24 2015-09-09 南车戚墅堰机车车辆工艺研究所有限公司 Automobile transmission gear heat treatment method

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