JP2007246941A - Component for high facial pressure and its production method - Google Patents
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 230000001815 facial effect Effects 0.000 title abstract 3
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 21
- 239000010959 steel Substances 0.000 claims abstract description 21
- 239000002344 surface layer Substances 0.000 claims abstract description 17
- 238000005255 carburizing Methods 0.000 claims description 22
- 238000010791 quenching Methods 0.000 claims description 16
- 230000000171 quenching effect Effects 0.000 claims description 16
- 238000005480 shot peening Methods 0.000 claims description 16
- 238000005496 tempering Methods 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 9
- 238000005498 polishing Methods 0.000 claims description 6
- 238000011282 treatment Methods 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 238000005256 carbonitriding Methods 0.000 claims description 5
- 239000010419 fine particle Substances 0.000 claims description 4
- 229910052797 bismuth Inorganic materials 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052758 niobium Inorganic materials 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 claims 1
- 229910052745 lead Inorganic materials 0.000 claims 1
- 229910052748 manganese Inorganic materials 0.000 claims 1
- 229910052750 molybdenum Inorganic materials 0.000 claims 1
- 229910052759 nickel Inorganic materials 0.000 claims 1
- 150000001247 metal acetylides Chemical class 0.000 abstract description 5
- 238000012360 testing method Methods 0.000 description 20
- 230000000694 effects Effects 0.000 description 17
- 239000000463 material Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 238000005452 bending Methods 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
- 229920006395 saturated elastomer Polymers 0.000 description 6
- 238000009863 impact test Methods 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 238000005242 forging Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 229910000760 Hardened steel Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000009661 fatigue test Methods 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010273 cold forging Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
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Abstract
Description
本発明は、高面圧の掛かる機械構造用鋼からなる部品(以下、「機械構造用部品」という。)、例えば焼入れ、浸炭、浸炭窒化などを施して製造される歯車やCVTなどの高面圧用部品に用いられる耐ピッチング性および耐摩耗性に優れる機械構造用部品とその製造方法に関する。 The present invention relates to parts made of steel for machine structures subjected to high surface pressure (hereinafter referred to as “machine structure parts”), such as gears and CVTs produced by quenching, carburizing, carbonitriding and the like. The present invention relates to a machine structural component having excellent pitting resistance and wear resistance used in a pressure component and a method for manufacturing the same.
機械構造用部品、例えば歯車などの高面圧を受ける部品は、鋼材を熱間鍛造、冷間鍛造、切削などにより部品形状に成形し、さらに浸炭を施して使用している。このような部品の用途の鋼材には、JIS−SCM420、JIS−SCr420などの低合金肌焼鋼が主に用いられている。例えば、このような低合金肌焼鋼からなる高面圧用部品の製造方法がすでに知られている(例えば、特許文献1、特許文献2参照。)。 Machine structural parts, such as parts that receive high surface pressure, such as gears, are formed by forming a steel material into a part shape by hot forging, cold forging, cutting, or the like, followed by carburizing. Low alloy case-hardened steels such as JIS-SCM420 and JIS-SCr420 are mainly used as steel materials for such parts. For example, a method for producing a high surface pressure component made of such a low alloy case-hardened steel is already known (see, for example, Patent Document 1 and Patent Document 2).
しかし、近年これらの鋼材からなる部品を使用する機械装置の高性能化、小型軽量化に伴い、使用条件が過酷になり、部品にかかる負荷が増大するに伴い、部品の耐ピッチング性、耐摩耗性、疲労強度のさらなる向上が求められている。 However, in recent years, with the improvement in performance and size and weight of machinery and equipment that use parts made of these steel materials, the use conditions become severe and the load on the parts increases, so the pitting resistance and wear resistance of the parts are increased. There is a demand for further improvement in fatigue and fatigue strength.
このような要求に対し有効な手段として、部材に対する高濃度浸炭が挙げられる。この高濃度浸炭方法は、浸炭材表層における炭素濃度を従来のCが0.8質量%程度よりも高いCが1.0〜1.5質量%とし、浸炭材表面のマルテンサイト組織に炭化物を分散させる表面処理方法である(例えば、非特許文献1参照)。しかしながら、この方法では長時間の熱処理が必要であり、このためコストが高くなる。また、炭化物を球状に制御する必要がある。なぜなら網目状の炭化物が析出した場合には、かえって部品の耐ピッチング性や疲労強度が低下してしまうという欠点があるためである。 As a means effective for such a requirement, high-concentration carburizing for members can be cited. In this high-concentration carburizing method, the carbon concentration in the surface layer of the carburized material is 1.0 to 1.5% by mass where C is higher than about 0.8% by mass of the conventional C, and carbide is added to the martensitic structure on the carburized material surface. This is a surface treatment method for dispersion (see, for example, Non-Patent Document 1). However, this method requires a long heat treatment, which increases the cost. Moreover, it is necessary to control the carbide to be spherical. This is because when the net-like carbide is precipitated, the pitting resistance and fatigue strength of the parts are reduced.
本発明が解決しようとする課題は、上記の問題を克服して、従来の高濃度浸炭による浸炭材の表層の炭素濃度をCが1.0〜1.5質量%のように高めることなく、耐ピッチング性、耐摩耗性、疲労強度、耐衝撃性に優れた機械構造用部品、特に高面圧用部品とその製造方法を提供することである。 The problem to be solved by the present invention is to overcome the above-described problems without increasing the carbon concentration of the surface layer of the carburized material by conventional high-concentration carburization such that C is 1.0 to 1.5 mass%, The object is to provide a machine structural component excellent in pitting resistance, wear resistance, fatigue strength, and impact resistance, particularly a component for high surface pressure, and a manufacturing method thereof.
上記の課題を達成するため本発明の手段は、請求項1の発明では、質量%で、Cr:1.50〜6.00%(好ましくは2.00〜5.50%)、Mo:0.01〜3.00%(好ましくは0.01〜1.50%)を含有し、Cr+2Mo:2.00〜8.00%(好ましくは2.00〜6.00%)である鋼からなり、表層において長径と短径の積の平方根(以下、「√(長径×短径)」という。)が2μm以上である炭化物が面積率で2%以下であることを特徴とする耐ピッチング強度、耐磨耗性に優れる高面圧用部品である。 In order to achieve the above object, according to the first aspect of the present invention, in the invention of claim 1, the mass is Cr: 1.50 to 6.00% (preferably 2.00 to 5.50%), Mo: 0. 0.01 to 3.00% (preferably 0.01 to 1.50%), Cr + 2Mo: 2.00 to 8.00% (preferably 2.00 to 6.00%) In the surface layer, a carbide having a square root of a product of a major axis and a minor axis (hereinafter referred to as “√ (major axis × minor axis)”) of 2 μm or more has an area ratio of 2% or less. This is a high surface pressure component with excellent wear resistance.
請求項2の発明では、上記の高面圧用部品は、請求項1の手段の鋼成分に加えて、質量%で、C:0.15〜0.60%(好ましくは0.20〜0.45%)、Si:0.01〜2.00%(好ましくは0.30〜1.00%)、Mn:0.01〜2.00%(好ましくは0.30〜1.50%)、Al:0.003〜0.050%(好ましくは0.003〜0.050%)、N:0.0050〜0.1000(好ましくは0.0080〜0.0200)を含有し、残部Feおよび不可避不純物からなり、表層において√(長径×短径)が2μm以上である炭化物が面積率で2%以下であることを特徴とする耐ピッチング性および耐磨耗性に優れる高面圧用部品である。 In the invention of claim 2, the high surface pressure component is C: 0.15 to 0.60% (preferably 0.20 to 0.000%) in mass% in addition to the steel component of the means of claim 1. 45%), Si: 0.01 to 2.00% (preferably 0.30 to 1.00%), Mn: 0.01 to 2.00% (preferably 0.30 to 1.50%), Al: 0.003 to 0.050% (preferably 0.003 to 0.050%), N: 0.0050 to 0.1000 (preferably 0.0080 to 0.0200), and the balance Fe and It is a component for high surface pressure that is excellent in pitting resistance and wear resistance, characterized in that carbide consisting of inevitable impurities and having √ (major axis x minor axis) of 2 μm or more in the surface layer is 2% or less in area ratio .
請求項3の発明では、上記の高面圧用部品は、上記請求項1または2の手段の鋼成分に加えて、質量%で、Ni:0.1〜2.0%、B:0.0001〜0.0020%、V:0.01〜0.50%、Nb:0.01〜0.20%、Ti:0.01〜0.20%から選択した1種または2種以上を含有し、表層において√(長径×短径)が2μm以上である炭化物が面積率で2%以下であることを特徴とする耐ピッチング性および耐磨耗性に優れる高面圧用部品である。 In the invention of claim 3, the high surface pressure component is Ni: 0.1 to 2.0%, B: 0.0001 in mass% in addition to the steel component of the means of claim 1 or 2. ~ 0.0020%, V: 0.01 to 0.50%, Nb: 0.01 to 0.20%, Ti: 0.01 to 0.20% or one or more selected from In the surface layer, a carbide having a √ (major axis × minor axis) of 2 μm or more is 2% or less in area ratio, and is a high surface pressure component excellent in pitting resistance and wear resistance.
請求項4の発明では、上記の高面圧用部品は、上記請求項1〜3のいずれか1項の手段の鋼成分に加えて、質量%で、S:0.001〜0.030%、Pb:0.01〜0.20%、Bi:0.01〜0.20%から選択した1種または2種以上を含有し、表層において√(長径×短径)が2μm以上である炭化物が面積率で2%以下であることを特徴とする耐ピッチング性および耐磨耗性に優れる高面圧用部品である。 In the invention of claim 4, the high surface pressure component is, in addition to the steel component of the means of any one of claims 1 to 3, mass%, S: 0.001 to 0.030%, A carbide containing one or more selected from Pb: 0.01 to 0.20%, Bi: 0.01 to 0.20%, and having a √ (major axis × minor axis) of 2 μm or more in the surface layer. It is a part for high surface pressure that is excellent in pitting resistance and wear resistance, characterized in that the area ratio is 2% or less.
請求項5の発明では、上記の請求項1〜4のいずれか1項の手段の鋼成分からなる高面圧用部品について、加熱温度を930〜1050℃(好ましくは950〜1000℃)、浸炭表層のC濃度を0.60〜0.80%、焼入れ温度を850〜900℃に制御して浸炭焼入れ、焼戻し処理または浸炭窒化焼入れ、焼戻し処理を施すことを特徴とする高面圧用部品の製造方法である。 In invention of Claim 5, about the high surface pressure components which consist of the steel component of the means of any one of said Claims 1-4, heating temperature is 930-1050 degreeC (preferably 950-1000 degreeC), Carburizing surface layer A method for producing a part for high surface pressure, wherein the carbon concentration is controlled to 0.60 to 0.80% and the quenching temperature is controlled to 850 to 900 ° C. to perform carburizing quenching, tempering treatment or carbonitriding quenching, tempering treatment It is.
さらに請求項6の発明では、上記の焼戻し処理した後、研磨、ショットピーニング、ハードショットピーニング、微粒子ショットピーニングのいずれか1種またはこの中の複数の表面硬化処理を行うことを特徴とする請求項5の手段の高面圧用部品の製造方法である。 Furthermore, in the invention of claim 6, after the tempering treatment, any one of polishing, shot peening, hard shot peening, and fine particle shot peening or a plurality of surface hardening treatments therein are performed. 5 is a method of manufacturing a high surface pressure component according to the fifth means.
以上に記載した通り、低合金肌焼鋼に浸炭を施した従来の材料の部品と比較して、本発明の手段の部品では、高Cr−Mo鋼を用い、高面圧用部品の素材に粗大な炭化物を生成させない浸炭焼入れ、焼戻しあるいは浸炭窒化焼入れ、焼戻しを施すことにより、(1)高Cr−Mo化によるマトリックスの強化、および(2)耐ピッチング性を低下させる粗大炭化物を防止することで、耐摩耗性、耐ピッチング性、耐衝撃性および疲労強度を高めている。 As described above, in comparison with the parts of the conventional material carburized the low alloy case-hardened steel, the parts of the means of the present invention use high Cr-Mo steel, and the material of the parts for high surface pressure is coarse. By carburizing, tempering, or carbonitriding and quenching, and tempering that do not generate tempered carbides, (1) strengthening the matrix by high Cr-Mo conversion, and (2) preventing coarse carbides that reduce pitting resistance Increases wear resistance, pitting resistance, impact resistance and fatigue strength.
さらに必要に応じて、研磨、ショットピーニングを施し、表面の浸炭異常層の除去、圧縮応力の付与により耐摩耗性、耐ピッチング性、耐衝撃性、疲労強度を高めている。 Furthermore, if necessary, polishing, shot peening are performed, and the wear resistance, pitting resistance, impact resistance, and fatigue strength are enhanced by removing the carburized abnormal layer on the surface and applying compressive stress.
以下に本発明の高面圧用部品の鋼成分の限定理由および処理条件の限定理由を説明する。 The reasons for limiting the steel components and the processing conditions for the high surface pressure parts of the present invention will be described below.
Cr:1.50〜6.00%、好ましくは2.00〜5.50%
Crは、後述のMoと同様に本発明で最も重要な元素の一つである。Crはマルテンサイト中に固溶することで、耐磨耗性、耐ピッチング性を著しく向上させる。その効果を得るためには、Crは1.50%以上が必要である。しかし、Crは6.00%を超えると、加工性が劣化し、網目状炭化物を生成して耐ピッチング性が低下する。そこでCrは1.50〜6.00%とし、好ましくは2.00〜5.50%とする。
Cr: 1.50 to 6.00%, preferably 2.00 to 5.50%
Cr is one of the most important elements in the present invention, like Mo described later. Cr dissolves in martensite, thereby significantly improving wear resistance and pitting resistance. In order to obtain the effect, Cr needs to be 1.50% or more. However, if Cr exceeds 6.00%, the workability deteriorates and a net-like carbide is generated to reduce the pitting resistance. Therefore, Cr is 1.50 to 6.00%, preferably 2.00 to 5.50%.
Moは0.01〜3.00%、好ましくは0.01〜1.50%
Moは、Crと同様本発明で最も重要な元素の一つである。Moは耐磨耗性、耐ピッチング性の向上および焼入れ性の確保に有効な元素である。その効果を得るためには、Moは0.01%が必要である。しかし、Moは3.00%を超えると加工性が劣化し、コストアップする。そこで、Moは0.01〜3.00%とし、好ましくは0.01〜1.50%とする。
Mo is 0.01 to 3.00%, preferably 0.01 to 1.50%
Mo, like Cr, is one of the most important elements in the present invention. Mo is an element effective for improving wear resistance and pitting resistance and ensuring hardenability. In order to obtain the effect, Mo needs to be 0.01%. However, if Mo exceeds 3.00%, workability deteriorates and costs increase. Therefore, Mo is 0.01 to 3.00%, preferably 0.01 to 1.50%.
なお、Cr+2Mo:2.00〜8.00%、好ましくは2.00〜6.00%
Cr+2Moは耐磨耗性の向上に最低2.00%必要である。しかし、Cr+2Moは多すぎると加工性が劣化する。そこで、Cr+2Moは2.00〜8.00%、好ましくは2.00〜6.00%とする。
Cr + 2Mo: 2.00 to 8.00%, preferably 2.00 to 6.00%
Cr + 2Mo needs to be at least 2.00% to improve wear resistance. However, if there is too much Cr + 2Mo, the workability deteriorates. Therefore, Cr + 2Mo is 2.00 to 8.00%, preferably 2.00 to 6.00%.
√(長径×短径):2μm以上の炭化物が面積率で2%以下
√(長径×短径)が2μm以上の炭化物は、耐ピッチング性を低下させる。2%以下ではその低下は許容できる範囲である。そこで、√(長径×短径):2μm以上の炭化物が面積率で2%以下とする。
√ (major axis × minor axis): 2 μm or more of carbide in area ratio is 2% or less √ (major axis × minor axis) of carbide having 2 μm or more deteriorates pitting resistance. Below 2%, the decrease is in an acceptable range. Therefore, √ (major axis × minor axis): Carbide of 2 μm or more is made 2% or less in area ratio.
C:0.15〜0.60%、好ましくは0.20〜0.45%
Cは高面圧用部品の芯部の硬さ確保に必要な元素である。そのためには、Cは0.15%以上は必要である。しかし、Cは多すぎると加工性が劣化する。そこで、Cは0.15〜0.60%、好ましくは0.20〜0.45%とする。
C: 0.15 to 0.60%, preferably 0.20 to 0.45%
C is an element necessary for ensuring the hardness of the core of the high surface pressure component. For that purpose, C is required to be 0.15% or more. However, when there is too much C, workability will deteriorate. Therefore, C is 0.15 to 0.60%, preferably 0.20 to 0.45%.
Si:0.01〜2.00%、好ましくは0.30〜1.00%
Siは脱酸に必要な元素であり、さらに、焼戻し軟化抵抗の向上にも有効な元素である。そのためにはSiは0.01%以上は必要である。しかし、Siが多すぎると、焼戻し軟化抵抗の効果が飽和し、さらに、硬さが上昇して加工性を劣化する。そこでSiは0.01〜2.00%、好ましくは0.30〜1.00%とする。
Si: 0.01 to 2.00%, preferably 0.30 to 1.00%
Si is an element necessary for deoxidation, and is also an element effective for improving temper softening resistance. For that purpose, Si needs to be 0.01% or more. However, when there is too much Si, the effect of the temper softening resistance is saturated, and further, the hardness is increased and the workability is deteriorated. Therefore, Si is 0.01 to 2.00%, preferably 0.30 to 1.00%.
Mn:0.01〜2.00%、好ましくは0.30〜1.50%
Mnは焼入れ性の確保に必要な元素であり、そのためには0.01%以上は必要である。しかし、Mnは多すぎると、硬さが上昇して加工性を劣化する。そこでMnは0.01〜2.00%、好ましくは0.30〜1.50%とする。
Mn: 0.01 to 2.00%, preferably 0.30 to 1.50%
Mn is an element necessary for ensuring hardenability, and for that purpose, 0.01% or more is necessary. However, when there is too much Mn, hardness will rise and workability will deteriorate. Therefore, Mn is 0.01 to 2.00%, preferably 0.30 to 1.50%.
Al:0.003〜0.050%
Alは脱酸に必要な元素であり、0.003%以下では脱酸が不充分である。しかし、Alは多すぎると、非金属介在物を生成して疲労強度が低下する。そこで、Alは0.003〜0.050%とする。
Al: 0.003 to 0.050%
Al is an element necessary for deoxidation, and deoxidation is insufficient at 0.003% or less. However, if there is too much Al, non-metallic inclusions are generated and the fatigue strength decreases. Therefore, Al is made 0.003 to 0.050%.
N:0.005〜0.100%、好ましくは、0.008〜0.020%
NはAlとAlNを形成して、浸炭時の結晶粒の粗大化を防止する。しかし、Nは0.005%未満ではその効果は小さく、0.100%を超えると結晶粒の粗大化防止効果が飽和する。そこでNは0.005〜0.100%、好ましくは、0.008〜0.020%とする。
N: 0.005 to 0.100%, preferably 0.008 to 0.020%
N forms Al and AlN to prevent coarsening of crystal grains during carburization. However, if N is less than 0.005%, the effect is small, and if it exceeds 0.100%, the effect of preventing the coarsening of crystal grains is saturated. Therefore, N is 0.005 to 0.100%, preferably 0.008 to 0.020%.
Ni:0.1〜2.0%
Niは靭性の向上に有効な元素である。しかし、Niは0.1%未満ではその効果はない。一方、Niは2.0%より多すぎると加工性の劣化を招き、コストアップとなる。そこで、Niは0.1〜2.0%とする。
Ni: 0.1 to 2.0%
Ni is an element effective for improving toughness. However, Ni is less effective at less than 0.1%. On the other hand, if Ni is more than 2.0%, the workability is deteriorated and the cost is increased. Therefore, Ni is set to 0.1 to 2.0%.
B:0.0001〜0.0020%
Bは焼入れ性の向上に有効な元素である。しかし、Bは0.0001%未満ではその効果はない。一方、Bは0.0020%を超えても、その効果は飽和する。そこで、Bは0.0001〜0.0020%とする。
B: 0.0001 to 0.0020%
B is an element effective for improving hardenability. However, if B is less than 0.0001%, the effect is not obtained. On the other hand, even if B exceeds 0.0020%, the effect is saturated. Therefore, B is set to 0.0001 to 0.0020%.
V:0.01〜0.50%
Vは結晶粒微細化に有効な元素である。しかし、Vは0.01未満ではその効果はない。一方、Vは0.50%を超えても結晶粒微細化の効果は飽和し、コストアップとなる。そこでVは0.01〜0.50%とする。
V: 0.01 to 0.50%
V is an element effective for grain refinement. However, when V is less than 0.01, there is no effect. On the other hand, even if V exceeds 0.50%, the effect of crystal grain refinement is saturated, resulting in an increase in cost. Therefore, V is set to 0.01 to 0.50%.
Nb:0.01〜0.20%
Nbは結晶粒微細化に有効な元素である。しかし、Nbは0.01未満ではその効果はない。一方、Nbは0.20%を超えても結晶粒微細化の効果は飽和し、コストアップとなる。そこで、Nbは0.01〜0.20%とする。
Nb: 0.01-0.20%
Nb is an element effective for grain refinement. However, if Nb is less than 0.01, the effect is not obtained. On the other hand, even if Nb exceeds 0.20%, the effect of crystal grain refinement is saturated and the cost increases. Therefore, Nb is set to 0.01 to 0.20%.
Ti:0.01〜0.20%
Tiは結晶粒微細化に有効な元素である。しかし、Tiは0.01未満ではその効果はない。一方、Tiは0.20%を超えても結晶粒微細化の効果は飽和し、加工性が劣化する。そこで、TiはTi:0.01〜0.20%とする。
Ti: 0.01-0.20%
Ti is an element effective for grain refinement. However, when Ti is less than 0.01, the effect is not obtained. On the other hand, even if Ti exceeds 0.20%, the effect of crystal grain refinement is saturated and workability deteriorates. Therefore, Ti is Ti: 0.01 to 0.20%.
S:0.001〜0.030%、好ましくは0.003から0.020%
Sは被削性の確保には有効な元素であり、その効果は0.001%以上で効果がある。しかし、Sは多すぎると耐ピッチング性および疲労強度が劣化する。そこでSは0.001〜0.030%、好ましくは0.003〜0.020%とする。
S: 0.001 to 0.030%, preferably 0.003 to 0.020%
S is an effective element for ensuring machinability, and the effect is effective at 0.001% or more. However, when S is too much, the pitting resistance and fatigue strength deteriorate. Therefore, S is 0.001 to 0.030%, preferably 0.003 to 0.020%.
Pb:0.01〜0.20%
Pbは被削性の確保には有効な元素であり、その効果は0.01%以上で効果がある。しかし、Pbは多すぎると耐ピッチング性および疲労強度が劣化する。そこでPbは0.01〜0.20%とする。
Pb: 0.01-0.20%
Pb is an effective element for ensuring machinability, and the effect is effective at 0.01% or more. However, when there is too much Pb, pitting resistance and fatigue strength deteriorate. Therefore, Pb is set to 0.01 to 0.20%.
Bi:0.01〜0.20%
Biは被削性の確保には有効な元素であり、その効果は0.01%以上で効果がある。しかし、Biは多すぎると耐ピッチング性および疲労強度が劣化する。そこでBiは0.01〜0.20%とする。
Bi: 0.01-0.20%
Bi is an effective element for ensuring machinability, and the effect is effective at 0.01% or more. However, when there is too much Bi, pitting resistance and fatigue strength deteriorate. Therefore, Bi is set to 0.01 to 0.20%.
浸炭加熱温度:930〜1050℃、好ましくは950〜1000℃
浸炭加熱温度が930℃未満であると網目状炭化物が多量に生成する。一方、浸炭加熱温度が1050℃を超えると、浸炭時に結晶粒の粗大化が生じて、疲労強度の低下を招く。そこで、浸炭加熱温度は930〜1050℃、好ましくは950〜1000℃とする。
Carburizing heating temperature: 930-1050 ° C, preferably 950-1000 ° C
When the carburizing heating temperature is lower than 930 ° C., a large amount of reticulated carbide is generated. On the other hand, when the carburizing heating temperature exceeds 1050 ° C., the coarsening of crystal grains occurs during carburizing, and the fatigue strength is reduced. Therefore, the carburizing heating temperature is 930 to 1050 ° C, preferably 950 to 1000 ° C.
浸炭表層のC濃度:0.60〜0.80%
浸炭表層のC濃度は高面圧部品に必要な表面硬さを確保するために0.60%以上は必要である。しかし、浸炭表層のC濃度は0.80%より高すぎると、網目状炭化物が多量に生成する。そこで、浸炭表層のC濃度は0.60〜0.80%とする。
C concentration of carburized surface layer: 0.60 to 0.80%
The C concentration of the carburized surface layer needs to be 0.60% or more in order to ensure the surface hardness required for high surface pressure parts. However, if the C concentration in the carburized surface layer is too higher than 0.80%, a large amount of reticulated carbide is generated. Therefore, the C concentration of the carburized surface layer is set to 0.60 to 0.80%.
焼入れ温度:850〜900℃
焼入れ温度は850℃未満であると、網目状炭化物が多量に生成する。一方、焼入れ温度は900℃を超えると、焼入れ後の歪みが増大して焼入れ時に割れが発生し易くなる。そこで、焼入れ温度は850〜900℃とする。
Quenching temperature: 850-900 ° C
If the quenching temperature is less than 850 ° C., a large amount of reticulated carbide is generated. On the other hand, if the quenching temperature exceeds 900 ° C., the strain after quenching increases and cracking is likely to occur during quenching. Therefore, the quenching temperature is set to 850 to 900 ° C.
本発明の手段とすることで、高面圧の掛かる機械構造用部品、例えば焼入れ、浸炭、浸炭窒化などを施して製造する歯車やCVTなどの高面圧用部品として、長時間の熱処理を必要とすることなく、耐ピッチング性および耐摩耗性に優れ、過酷な使用条件下で部品に掛かる負荷の増大する自動車の静粛性を向上し、さらに軽量化を低コストで可能とするなど、本発明は優れた効果を奏する。 By using the means of the present invention, mechanical structural parts subject to high surface pressure, for example, gears manufactured by quenching, carburizing, carbonitriding, etc., and high surface pressure parts such as CVT require long-time heat treatment. In addition, the present invention is excellent in pitting resistance and wear resistance, improves the quietness of automobiles that increase the load on parts under severe use conditions, and enables weight reduction at low cost. Excellent effect.
本発明を実施するための最良の形態を、以下の実施例の発明例および比較例の試験を通じて説明する。 BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described through tests of invention examples and comparative examples of the following examples.
先ず、本実験に適用した試験片の製造工程について説明する。100kg真空溶解炉にて、表1に示す化学成分を含む鋼を溶解して得た鋼から、熱間鍛造にてφ32mmの丸棒に製作した。 First, the manufacturing process of the test piece applied to this experiment is demonstrated. From a steel obtained by melting steel containing chemical components shown in Table 1 in a 100 kg vacuum melting furnace, a round bar having a diameter of 32 mm was manufactured by hot forging.
本発明成分例は、上記の熱間鍛造にて製造したφ32mmの丸棒から、機械加工によりローラーピッチング試験片、シャルピー衝撃試験片、小野式回転曲げ試験片をそれぞれ製作した。次いで、浸炭温度条件:920〜1050℃にて浸炭および拡散を行った後、830〜900℃より60℃の油中にて焼入れし、180℃で焼戻しを行った。焼戻し後、表面を0.1mm研磨により試験片を仕上げた。なお、浸炭炉内雰囲気は、浸炭後の表層が0.60〜1.00%となるように制御し、次いで180℃にて焼戻しを行った。一方、比較成分例については、上記の熱間鍛造にてφ32mmの丸棒から、機械加工によりローラーピッチング試験片、シャルピー衝撃試験片、小野式回転曲げ試験片をそれぞれ製作し、浸炭条件:920℃にて浸炭および拡散を行った後、830℃より60℃の油中にて焼入れし、180℃で焼戻しを行った。焼戻し後、表面を0.1mm研磨により試験片を仕上げた。表2に浸炭の条件と得られた表面から0.5mmまでの√(長径×短径)が2μm以上の炭化物の面積率を測定した。測定面積は、0.25mm2である。さらに、本発明例の√(長径×短径):2μm以上の炭化物が面積率は2%以下であった。 In the component examples of the present invention, a roller pitching test piece, a Charpy impact test piece, and an Ono-type rotary bending test piece were each produced by machining from a φ32 mm round bar produced by hot forging. Then, after carburizing and diffusing at carburizing temperature conditions: 920 to 1050 ° C., quenching was performed in oil at 60 ° C. from 830 to 900 ° C., and tempering was performed at 180 ° C. After tempering, the test piece was finished by polishing the surface with 0.1 mm. The atmosphere in the carburizing furnace was controlled so that the surface layer after carburizing was 0.60 to 1.00%, and then tempered at 180 ° C. On the other hand, for the comparative component examples, roller pitching test pieces, Charpy impact test pieces, and Ono-type rotary bending test pieces were produced from the round bar of φ32 mm by hot forging as described above, and carburizing conditions: 920 ° C. After carburizing and diffusing, the steel was quenched in oil at 830 ° C to 60 ° C and tempered at 180 ° C. After tempering, the test piece was finished by polishing the surface with 0.1 mm. Table 2 shows the carburizing conditions and the area ratio of carbides having a √ (major axis × minor axis) of 2 μm or more from the surface to 0.5 mm. The measurement area is 0.25 mm 2 . Further, √ (major axis × minor axis) of the present invention example: the area ratio of carbides of 2 μm or more was 2% or less.
これらの試験片を用いて、先ず、以下の条件にてローラーピッチング試験を行った。また、同試験において摩耗量を測定した。摩耗量の測定は、面圧:3440MPa、滑り率:−40%、油温度:80℃、回転数:1×106回でのローラーピッチング試験片の摺動部の凹み深さを測定し、摩耗量として評価した。さらにシャルピー衝撃試験および小野式回転曲げ試験を行った。なお、試験片は、シャルピー衝撃試験では角10mmの10RCノッチ、小野式回転曲げ疲労試験では平行部がφ8mmの切欠き回転曲げ疲労試験片を使用した。これらの試験によって得られた結果を表3に示す。 Using these test pieces, a roller pitching test was first performed under the following conditions. In addition, the amount of wear was measured in the same test. The amount of wear was measured by measuring the dent depth of the sliding portion of the roller pitching test piece at a surface pressure of 3440 MPa, a slip rate of −40%, an oil temperature of 80 ° C., and a rotation speed of 1 × 10 6 times. The amount of wear was evaluated. In addition, Charpy impact test and Ono type rotary bending test were conducted. The test piece used was a 10 RC notch with a 10 mm square in the Charpy impact test, and a notched rotary bending fatigue test piece with a parallel portion of φ8 mm in the Ono type rotary bending fatigue test. Table 3 shows the results obtained by these tests.
表3に示したとおり、本発明例は、比較例に比して耐摩耗性、耐ピッチング性、疲労強度、耐衝撃性で優れていることが分かる。特に、耐磨耗性においては、本発明成分のものは比較成分1、2である比較例5、6に比して極めて優れていることが判った。 As shown in Table 3, it can be seen that the inventive examples are superior in wear resistance, pitting resistance, fatigue strength, and impact resistance compared to the comparative examples. In particular, it was found that the components of the present invention are extremely superior in abrasion resistance as compared with Comparative Examples 5 and 6 which are Comparative Components 1 and 2.
次に、仕上げ研磨した後に、表4に規定する条件のショットピーニング、ハードショットピーニング、および微粒子ショットピーニングを行った。 Next, after finish polishing, shot peening, hard shot peening, and fine particle shot peening under the conditions specified in Table 4 were performed.
それらについて以下の条件にてローラーピッチング試験を行った。さらに、同試験において摩耗量を測定した。摩耗量の測定は、面圧:3440MPa、滑り率:−40%、油温度:80℃、回転数:1×106回におけるローラーピッチング試験片の摺動部の凹み深さを測定し、摩耗量として評価した。さらにシャルピー衝撃試験および小野式回転曲げ試験を行った。これらの試験によって得られた結果を表5に示す。 They were subjected to a roller pitching test under the following conditions. Furthermore, the amount of wear was measured in the same test. The amount of wear was measured by measuring the dent depth of the sliding portion of the roller pitching test piece at a contact pressure of 3440 MPa, a slip rate of −40%, an oil temperature of 80 ° C., and a rotation speed of 1 × 10 6 times. Evaluated as a quantity. In addition, Charpy impact test and Ono type rotary bending test were conducted. Table 5 shows the results obtained by these tests.
表5に、表4の各種のショットピーニングを施さないものと、各種のショットピーニングを施したものを、発明例1、発明例8、発明例11、発明例3で対比し、さらにショットピーニングを施さない比較例5を対比して示した。なお、発明例3はハードショットピーニングと微粒子ショットピーニングの処理を共に施したものとの対比を示す。この表5から各種のショットピーニングを施すことにより特に疲労強度が向上することが判明した。これに対して比較例5は特に耐摩耗性が劣っていることがわかる。 In Table 5, those not subjected to various shot peening in Table 4 and those subjected to various shot peening are compared in Invention Example 1, Invention Example 8, Invention Example 11, Invention Example 3, and further shot peening is performed. Comparative example 5 which is not applied is shown in comparison. Inventive Example 3 shows a comparison with the case where both hard shot peening and fine particle shot peening were performed. From Table 5, it was found that the fatigue strength is particularly improved by performing various shot peening. On the other hand, it can be seen that Comparative Example 5 is particularly inferior in wear resistance.
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JP2009114484A (en) * | 2007-11-02 | 2009-05-28 | Sanyo Special Steel Co Ltd | Method for manufacturing high-strength carburized component |
JP2009127095A (en) * | 2007-11-26 | 2009-06-11 | Sumitomo Metal Ind Ltd | Case-hardening steel for power transmission component |
US8475605B2 (en) | 2010-03-19 | 2013-07-02 | Nippon Steel & Sumitomo Metal Corporation | Surface layer-hardened steel part and method of manufacturing the same |
US8961710B2 (en) | 2009-05-27 | 2015-02-24 | Nippon Steel & Sumitomo Metal Corporation | Carburized component and manufacturing method |
JP2016050350A (en) * | 2014-09-01 | 2016-04-11 | 山陽特殊製鋼株式会社 | Steel component for high strength high toughness machine structure excellent in pitching resistance and abrasion resistance and manufacturing method therefor |
US9587288B2 (en) | 2012-03-30 | 2017-03-07 | Kobe Steel, Ltd. | Gear having excellent seizing resistance |
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JPH07188895A (en) * | 1993-12-28 | 1995-07-25 | Kobe Steel Ltd | Manufacture of parts for machine structure use |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2009114484A (en) * | 2007-11-02 | 2009-05-28 | Sanyo Special Steel Co Ltd | Method for manufacturing high-strength carburized component |
JP2009127095A (en) * | 2007-11-26 | 2009-06-11 | Sumitomo Metal Ind Ltd | Case-hardening steel for power transmission component |
US8961710B2 (en) | 2009-05-27 | 2015-02-24 | Nippon Steel & Sumitomo Metal Corporation | Carburized component and manufacturing method |
US8475605B2 (en) | 2010-03-19 | 2013-07-02 | Nippon Steel & Sumitomo Metal Corporation | Surface layer-hardened steel part and method of manufacturing the same |
US9587288B2 (en) | 2012-03-30 | 2017-03-07 | Kobe Steel, Ltd. | Gear having excellent seizing resistance |
JP2016050350A (en) * | 2014-09-01 | 2016-04-11 | 山陽特殊製鋼株式会社 | Steel component for high strength high toughness machine structure excellent in pitching resistance and abrasion resistance and manufacturing method therefor |
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