JP6658143B2 - Rolling sliding member and rolling bearing - Google Patents
Rolling sliding member and rolling bearing Download PDFInfo
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- JP6658143B2 JP6658143B2 JP2016050224A JP2016050224A JP6658143B2 JP 6658143 B2 JP6658143 B2 JP 6658143B2 JP 2016050224 A JP2016050224 A JP 2016050224A JP 2016050224 A JP2016050224 A JP 2016050224A JP 6658143 B2 JP6658143 B2 JP 6658143B2
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- 239000002245 particle Substances 0.000 claims description 120
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- 239000002244 precipitate Substances 0.000 claims description 87
- 229910000831 Steel Inorganic materials 0.000 claims description 47
- 239000010959 steel Substances 0.000 claims description 47
- 229910001566 austenite Inorganic materials 0.000 claims description 42
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 8
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 6
- 230000013011 mating Effects 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 4
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims description 3
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- 229910052757 nitrogen Inorganic materials 0.000 description 5
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
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- VNTLIPZTSJSULJ-UHFFFAOYSA-N chromium molybdenum Chemical compound [Cr].[Mo] VNTLIPZTSJSULJ-UHFFFAOYSA-N 0.000 description 2
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- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
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- Rolling Contact Bearings (AREA)
- Heat Treatment Of Articles (AREA)
Description
本発明は、転がり摺動部材及び当該転がり摺動部材を備える転がり軸受に関する。 The present invention relates to a rolling sliding member and a rolling bearing provided with the rolling sliding member.
近年、産業機械等の高性能化に伴い、軸受等に用いられる転がり摺動部材は、高荷重条件等の厳しい使用条件下で使用されることが多くなっている。そのため、前記使用条件下においても、長い転動疲労寿命を有する転がり摺動部材が求められている。 2. Description of the Related Art In recent years, with the advancement of performance of industrial machines and the like, rolling sliding members used for bearings and the like are often used under severe use conditions such as high load conditions. Therefore, there is a need for a rolling sliding member having a long rolling fatigue life even under the above use conditions.
そこで、高荷重条件下に用いられる転がり軸受では、当該転がり軸受を構成する転がり摺動部材を構成する鋼材の表面層において、析出強化法によって析出物を析出させることにより、長寿命化を図ることが提案されている（例えば、特許文献１参照）。 Therefore, in a rolling bearing used under a high load condition, the life is extended by depositing precipitates by a precipitation strengthening method on a surface layer of a steel material constituting a rolling sliding member constituting the rolling bearing. Has been proposed (for example, see Patent Document 1).
しかし、前記特許文献１に記載の転がり摺動部材では、析出物面積率が３０％を超える場合、析出物がはく離の起点となるため、かえって転動疲労寿命が短くなることがある。また、前記析出強化法は、析出物を析出させるための熱処理に際し、多くの工程数を要することから、製造コストの増大を招くという欠点がある。 However, in the rolling sliding member described in Patent Document 1, when the precipitate area ratio exceeds 30%, the precipitate becomes a starting point of peeling, and the rolling fatigue life may be shortened. In addition, the precipitation strengthening method has a drawback in that the heat treatment for depositing precipitates requires a large number of steps, which leads to an increase in manufacturing cost.
本発明は、このような実状に鑑みてなされたもので、安価に製造することができ、高荷重条件下においても、長い転動疲労寿命を確保することができる転がり摺動部材及び転がり軸受を提供することを目的とする。 The present invention has been made in view of such circumstances, and can be manufactured at a low cost, and can provide a long rolling fatigue life even under high load conditions. The purpose is to provide.
本発明は、１つの側面では、相手部材との間で相対的に接触する転がり摺動面を有する転がり摺動部材であって、炭素０．１〜０．５質量％と、ケイ素０．３５質量％以下と、マンガン０．３〜１．０質量％と、クロム０．９〜２．５質量％と、モリブデン０．５〜０．９質量％とを含有し、残部が鉄及び不可避的不純物である鋼材の表面層が表面硬化層である母材からなり、前記転がり摺動面から最大直交せん断応力発生深さの位置におけるビッカース硬さＨｖが７００〜８００（ロックウェルＣ硬さＨＲＣが６０〜６４）であり、前記転がり摺動面から前記最大直交せん断応力発生深さの位置における残留オーステナイト量が２５〜５０体積％であり、前記転がり摺動面から前記最大直交せん断応力発生深さの位置における析出物粒子の平均粒径が１〜５μｍであり、前記転がり摺動面から前記最大直交せん断応力発生深さの位置における前記析出物粒子の最近接粒子間距離が１５〜２５μｍであることを特徴とする転がり摺動部材に関する。 The present invention, in one aspect, is a rolling sliding member having a rolling sliding surface relatively in contact with a mating member, wherein 0.1 to 0.5% by mass of carbon and 0.35% of silicon are contained. % By mass, 0.3 to 1.0% by mass of manganese, 0.9 to 2.5% by mass of chromium, and 0.5 to 0.9% by mass of molybdenum, with the balance being iron and inevitable The surface layer of the steel material as the impurity is made of a base material that is a hardened surface layer, and has a Vickers hardness Hv of 700 to 800 (Rockwell C hardness HRC at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface. 60 to 64), wherein the amount of retained austenite at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 25 to 50% by volume, and the maximum orthogonal shear stress generating depth from the rolling sliding surface is Of the precipitate particles at the position A rolling particle having an average particle size of 1 to 5 μm, and a distance between closest particles of the precipitate particles at a position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 15 to 25 μm; It relates to a moving member.
本実施形態に係る転がり摺動部材においては、前記転がり摺動面から最大直交せん断応力発生深さの位置におけるビッカース硬さＨｖが７００〜８００（ロックウェルＣ硬さＨＲＣが６０〜６４）、前記転がり摺動面から前記最大直交せん断応力発生深さの位置における残留オーステナイト量が２５〜５０体積％、前記位置における析出物粒子の平均粒径が１〜５μｍ、及び前記位置における前記析出物粒子の最近接粒子間距離が１５〜２５μｍである。そのため、本実施形態に係る転がり摺動部材は、転がり軸受の構成部材として用いられた場合に最も大きい直交せん断応力が発生する深さの位置において、転動体の転動に伴なう残留オーステナイトの応力誘起マルテンサイト変態を起こしやすい組織構造を有している。したがって、本実施形態に係る転がり摺動部材は、高荷重条件下においても、長い転動疲労寿命を確保することができる。また、本実施形態に係る転がり摺動部材は、前記鋼材が用いられているため、製造に際して、少ない工程数の熱処理で前記組織構造を得ることができる。したがって、本実施形態に係る転がり摺動部材は、安価に製造することができる。 In the rolling sliding member according to the present embodiment, the Vickers hardness Hv at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 700 to 800 (Rockwell C hardness HRC is 60 to 64), The amount of retained austenite at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 25 to 50% by volume, the average particle size of the precipitate particles at the position is 1 to 5 μm, and the amount of the precipitate particles at the position is The distance between the closest particles is 15 to 25 μm. Therefore, the rolling sliding member according to the present embodiment, at a position where the largest orthogonal shear stress occurs when used as a component of the rolling bearing, the residual austenite accompanying the rolling of the rolling element It has a structure that is susceptible to stress-induced martensitic transformation. Therefore, the rolling sliding member according to the present embodiment can secure a long rolling fatigue life even under a high load condition. Further, since the rolling sliding member according to the present embodiment uses the steel material, the microstructure can be obtained with a small number of heat treatment steps during manufacturing. Therefore, the rolling sliding member according to the present embodiment can be manufactured at low cost.
本発明の転がり軸受は、内周に転がり摺動面を有する外輪と、外周に転がり摺動面を有する内輪と、前記外内輪の両転がり摺動面の間に配置された複数個の転動体とを有する転がり軸受であって、前記外輪、内輪及び転動体のうちの少なくとも１つが、前述した転がり摺動部材であることを特徴としている。したがって、本発明の転がり軸受は、前述した転がり摺動部材を備えているので、前述の優れた作用効果を奏する。 A rolling bearing according to the present invention includes an outer ring having a rolling sliding surface on an inner periphery, an inner ring having a rolling sliding surface on an outer periphery, and a plurality of rolling elements disposed between the rolling sliding surfaces of the outer and inner rings. And wherein at least one of the outer ring, the inner ring, and the rolling element is the above-described rolling sliding member. Therefore, since the rolling bearing of the present invention includes the above-described rolling sliding member, the above-described excellent operation and effect can be obtained.
本発明の転がり摺動部材及び転がり軸受によれば、安価に製造でき、高荷重条件下においても、長い転動疲労寿命を確保できる。 ADVANTAGE OF THE INVENTION According to the rolling sliding member and rolling bearing of this invention, it can manufacture inexpensively and can secure long rolling fatigue life even under high load conditions.
［転がり軸受］
以下、添付の図面により本発明の一実施形態に係る転がり軸受及び転がり摺動部材を説明する。以下においては、転がり軸受の一例として玉軸受を挙げて説明する。図１は、本発明の一実施形態に係る転がり軸受の一例である玉軸受を示す要部断面図である。
[Rolling bearing]
Hereinafter, a rolling bearing and a rolling sliding member according to an embodiment of the present invention will be described with reference to the accompanying drawings. Hereinafter, a ball bearing will be described as an example of the rolling bearing. FIG. 1 is a sectional view of a main part showing a ball bearing which is an example of a rolling bearing according to an embodiment of the present invention.
図１に示される玉軸受１は、外輪１０と、外輪１０の内周側に当該外輪１０と同心に配置された内輪２０と、外内輪１０，２０間に配列された複数個の転動体（玉３０）と、複数個の玉３０を保持する保持器４０とを備えている。 A ball bearing 1 shown in FIG. 1 includes an outer ring 10, an inner ring 20 arranged concentrically with the outer ring 10 on the inner peripheral side of the outer ring 10, and a plurality of rolling elements ( Ball 30) and a holder 40 for holding a plurality of balls 30.
図１に示される玉軸受１においては、外内輪１０，２０及び玉３０のそれぞれが、後述の本発明の一実施形態に係る転がり摺動部材である。なお、本発明においては、外内輪１０，２０及び玉３０のうちの少なくとも１つが、後述の本発明の一実施形態に係る転がり摺動部材であればよい。また、本発明においては、転がり軸受は、特に限定されるものではなく、例えば、円筒ころ軸受、円すいころ軸受等の他の転がり軸受であってもよい。 In the ball bearing 1 shown in FIG. 1, each of the outer and inner races 10, 20 and the ball 30 is a rolling sliding member according to an embodiment of the present invention described later. In the present invention, at least one of the outer and inner races 10, 20 and the ball 30 may be a rolling sliding member according to an embodiment of the present invention described later. In the present invention, the rolling bearing is not particularly limited, and may be another rolling bearing such as a cylindrical roller bearing or a tapered roller bearing.
［転がり摺動部材］
本実施形態に係る転がり摺動部材としての外輪１０は、鋼材１０ａ１の表面層が表面硬化層１０ａ２である母材１０ａからなる。外輪１０の内周面には、複数個の玉３０が転動する軌道部１１ａが形成されている。軌道部１１ａの表面は、相手部材である玉３０との間で相対的に転がり接触若しくは滑り接触又は両接触を含む接触をする転がり摺動面である。なお、外輪１０の軌道部１１ａ、端面１１ｂ、肩面１１ｃ及び外周面１１ｄは、研磨仕上げが施された研磨部である。
[Rolling sliding member]
The outer ring 10 as a rolling sliding member according to the present embodiment is made of a base material 10a in which a surface layer of a steel material 10a1 is a hardened layer 10a2. A track portion 11a on which a plurality of balls 30 roll is formed on the inner peripheral surface of the outer ring 10. The surface of the raceway portion 11a is a rolling sliding surface that relatively makes a rolling contact, a sliding contact, or a contact including a double contact with the ball 30 as a mating member. In addition, the raceway portion 11a, the end surface 11b, the shoulder surface 11c, and the outer peripheral surface 11d of the outer race 10 are polished portions that have been polished.
本実施形態に係る転がり摺動部材としての内輪２０は、鋼材２０ａ１の表面層が表面硬化層２０ａ２である母材２０ａからなる。内輪２０の外周面には、軌道部１１ａに対向するとともに、複数個の玉３０が転動する軌道部２１ａが形成されている。軌道部２１ａの表面は、相手部材である玉３０との間で相対的に転がり接触若しくは滑り接触又は両接触を含む接触をする転がり摺動面である。内輪２０の軌道部２１ａ、端面２１ｂ、肩面２１ｃ及び内周面２１ｄは、研磨仕上げが施された研磨部である。 The inner race 20 as the rolling sliding member according to the present embodiment is made of a base material 20a in which a surface layer of a steel material 20a1 is a hardened layer 20a2. On the outer peripheral surface of the inner race 20, there is formed a track portion 21a opposed to the track portion 11a and on which a plurality of balls 30 roll. The surface of the raceway portion 21a is a rolling sliding surface that relatively makes rolling contact, sliding contact, or contact including both contacts with the ball 30 as a mating member. The raceway portion 21a, the end surface 21b, the shoulder surface 21c, and the inner peripheral surface 21d of the inner ring 20 are polished portions that have been polished.
本実施形態に係る転がり摺動部材としての玉３０は、鋼材３０ａ１の表面層が表面硬化層３０ａ２である母材３０ａからなる。玉３０の表面は、相手部材である外内輪１０，２０それぞれとの間で相対的に転がり接触若しくは滑り接触又は両接触を含む接触をする転がり摺動面である。 The ball 30 as a rolling sliding member according to the present embodiment is made of a base material 30a in which a surface layer of a steel material 30a1 is a surface hardened layer 30a2. The surface of the ball 30 is a rolling sliding surface that relatively makes rolling contact, sliding contact, or contact including both contact between the outer and inner rings 10 and 20 as the mating members.
本明細書において、「表面硬化層」は、ビッカース硬さＨｖが７００〜８００（ロックウェルＣ硬さＨＲＣが６０〜６４）である層をいう。表面硬化層１０ａ２，２０ａ２，３０ａ２は、例えば、前記鋼材に対し、後述の浸炭処理又は浸炭窒化処理と、焼戻しとを行なうこと等によって形成させることができる。なお、本明細書において、ビッカース硬さＨｖは、ＪＩＳ Ｚ ２２４４に記載の方法にしたがって測定された値である。 In the present specification, the “surface-hardened layer” refers to a layer having a Vickers hardness Hv of 700 to 800 (Rockwell C hardness HRC of 60 to 64). The surface hardened layers 10a2, 20a2, and 30a2 can be formed, for example, by performing carburizing treatment or carbonitriding treatment to be described later and tempering the steel material. In this specification, the Vickers hardness Hv is a value measured according to the method described in JIS Z 2244.
前記鋼材は、炭素０．１〜０．５質量％と、ケイ素０．３５質量％以下と、マンガン０．３〜１．０質量％と、クロム０．９〜２．５質量％と、モリブデン０．５〜０．９質量％とを含有し、残部が鉄及び不可避不純物である鋼材からなる。前記不可避不純物は、鋼材を製造する際に、原料等から混入する物質であって、本発明の目的を阻害しない範囲で許容される物質を意味する。前記不可避不純物としては、例えば、リン、硫黄、アルミニウム、窒素、酸素、ボロン、ニオブ、チタン等が挙げられる。外内輪１０，２０及び玉３０は、前記鋼材が用いられているため、少ない工程数の熱処理で製造することができる。したがって、外内輪１０，２０及び玉３０は、安価に製造することができる。 The steel material contains 0.1 to 0.5% by mass of carbon, 0.35% by mass or less of silicon, 0.3 to 1.0% by mass of manganese, 0.9 to 2.5% by mass of chromium, and molybdenum. 0.5 to 0.9% by mass, the balance being iron and a steel material which is an inevitable impurity. The unavoidable impurities are substances that are mixed in from the raw materials and the like when producing steel products, and mean substances that are allowed as long as the object of the present invention is not impaired. Examples of the unavoidable impurities include phosphorus, sulfur, aluminum, nitrogen, oxygen, boron, niobium, and titanium. Since the outer and inner rings 10 and 20 and the balls 30 are made of the above-described steel material, they can be manufactured by a small number of heat treatments. Therefore, the outer and inner rings 10, 20 and the balls 30 can be manufactured at low cost.
炭素は、転がり摺動部材の製造時における鋼材の焼入れ性を確保し、強度確保のための内部硬さを得るための元素である。しかしながら、鋼材における炭素の含有量が過剰量である場合、母材が硬くなりすぎ、熱間加工性の低下、切削時の工具寿命の低下などを引き起こす。前記鋼材における炭素の含有量は、十分な内部硬さを得る観点から、０．１質量％以上、好ましくは０．１５質量％以上であり、熱処理前の加工性を十分に得る観点から、０．５質量％以下、好ましくは０．４５質量％以下である。 Carbon is an element for securing the hardenability of the steel material at the time of manufacturing the rolling sliding member and obtaining the internal hardness for securing the strength. However, if the content of carbon in the steel material is excessive, the base material becomes too hard, causing a reduction in hot workability and a reduction in tool life during cutting. The carbon content in the steel material is 0.1% by mass or more, preferably 0.15% by mass or more from the viewpoint of obtaining sufficient internal hardness, and 0 from the viewpoint of sufficiently obtaining workability before heat treatment. It is at most 0.5 mass%, preferably at most 0.45 mass%.
ケイ素は、鋼の製錬時の脱酸のために必要な元素である。また、ケイ素は、炭化物に固溶しにくい性質を有するため、析出物の成長を抑制し、粗大化を防ぐための元素である。しかしながら、鋼材におけるケイ素の含有量が過剰量である場合、フェライトの強化によって硬さが上昇するため、鋼材の加工性が悪化する。前記鋼材におけるケイ素の含有量は、粗大な析出物の生成を抑制する観点から、０．０５質量％以上、好ましくは０．０７％以上であり、熱処理前において、十分な加工性を確保する観点から、０．３５質量％以下、好ましくは０．３３質量％以下である。 Silicon is an element necessary for deoxidation during smelting of steel. Further, silicon has a property of hardly forming a solid solution with carbides, and is an element for suppressing the growth of precipitates and preventing coarsening. However, when the silicon content in the steel material is excessive, the hardness increases due to the strengthening of ferrite, and the workability of the steel material deteriorates. The content of silicon in the steel material is 0.05% by mass or more, preferably 0.07% or more, from the viewpoint of suppressing generation of coarse precipitates, and from the viewpoint of ensuring sufficient workability before heat treatment. Therefore, the content is 0.35% by mass or less, preferably 0.33% by mass or less.
マンガンは、転がり摺動部材の製造時における鋼材の焼入れ性を確保し、強度確保のための内部硬さを得るための元素である。さらに、マンガンは、オーステナイトを安定化させる元素であるため、鋼材におけるマンガンの含有量を増やすことにより、オーステナイトを容易に増加させることができる。しかしながら、マンガンは、熱処理加熱時に炭化物の固溶温度の低下をもたらすことから、鋼材におけるマンガンの含有量が過剰量である場合、析出物の径が小さくなるため、十分な寿命が得られない。前記鋼材におけるマンガンの含有量は、十分な焼入れ性と残留オーステナイト量を得る観点から０．３質量％以上、好ましくは０．３５質量％以上であり、適切な大きさの析出物を残存させる観点から１．０質量％以下、好ましくは０．９５質量％以下である。 Manganese is an element for securing the hardenability of the steel material at the time of manufacturing the rolling sliding member and obtaining the internal hardness for securing the strength. Furthermore, since manganese is an element that stabilizes austenite, austenite can be easily increased by increasing the content of manganese in a steel material. However, since manganese lowers the solid solution temperature of carbides during heat treatment, if the manganese content in the steel material is excessive, the diameter of the precipitates becomes small, so that a sufficient life cannot be obtained. The content of manganese in the steel material is at least 0.3% by mass, preferably at least 0.35% by mass, from the viewpoint of obtaining sufficient hardenability and the amount of retained austenite, and the viewpoint of leaving precipitates of an appropriate size. To 1.0% by mass or less, preferably 0.95% by mass or less.
クロムは、転がり摺動部材の製造時における鋼材の焼入れ性を高め、モリブデンとの複合添加によって析出物を形成し、硬さを上昇させるための元素である。しかしながら、鋼材におけるクロムの含有量が過剰量である場合、熱処理前の未固溶炭化物の量が増加し、当該未固溶炭化物が析出核として働く。そのため、熱処理後の析出物の粒子間距離が小さくなり、十分な寿命が得られない。前記鋼材におけるクロムの含有量は、十分な硬さを得る観点から、０．９質量％以上、好ましくは０．９５質量％以上であり、熱処理後の析出物の粒子間距離を確保する観点から、２．５質量％以下、好ましくは２．４５質量％以下である。 Chromium is an element for increasing the hardenability of steel at the time of manufacturing a rolling sliding member, forming a precipitate by adding it in combination with molybdenum, and increasing the hardness. However, when the content of chromium in the steel material is excessive, the amount of undissolved carbide before the heat treatment increases, and the undissolved carbide acts as a precipitation nucleus. Therefore, the interparticle distance of the precipitate after the heat treatment becomes small, and a sufficient life cannot be obtained. The chromium content in the steel material is 0.9% by mass or more, preferably 0.95% by mass or more from the viewpoint of obtaining sufficient hardness, and from the viewpoint of securing the interparticle distance of the precipitate after heat treatment. , 2.5% by mass or less, preferably 2.45% by mass or less.
モリブデンは、クロムと同様に鋼材の焼入れ性を高め、クロムとの複合添加によって析出物を形成し、硬さを上昇させるための元素である。しかしながら、モリブデンは、炭素との親和力が非常に強いため、鋼材におけるモリブデンの含有量が過剰量である場合、析出物の粗大化をまねく。前記鋼材におけるモリブデンの含有量は、十分な硬さを得る観点から０．５質量％以上、好ましくは０．５５質量％以上であり、粗大な析出物を形成させない観点から０．９質量％以下、好ましくは０．８５質量％以下である。 Molybdenum is an element that enhances the hardenability of steel, like chromium, forms precipitates when combined with chromium, and increases hardness. However, since molybdenum has a very strong affinity for carbon, when the content of molybdenum in the steel material is excessive, the precipitation becomes coarse. The content of molybdenum in the steel material is 0.5% by mass or more, preferably 0.55% by mass or more from the viewpoint of obtaining sufficient hardness, and 0.9% by mass or less from the viewpoint of not forming coarse precipitates. , Preferably 0.85% by mass or less.
外内輪１０，２０の軌道部１１ａ，２１ａ及び玉３０それぞれの転がり摺動面から最大直交せん断応力発生深さの位置において、ビッカース硬さＨｖは、転がり軸受として十分な転動疲労寿命及び静的負荷容量を確保する観点から、７００（ロックウェルＣ硬さＨＲＣ６０）以上、好ましくは７１０（ロックウェルＣ硬さＨＲＣ６０．６）以上であり、脆化を抑制し、十分な靱性を確保する観点から、８００（ロックウェルＣ硬さＨＲＣ６４）以下、好ましくは７９０（ロックウェルＣ硬さＨＲＣ６３．６）以下である。 At the position where the maximum orthogonal shear stress is generated from the rolling sliding surfaces of the raceways 11a, 21a of the outer and inner races 10, 20 and the ball 30, the Vickers hardness Hv is sufficient for a rolling bearing to have sufficient rolling fatigue life and static From the viewpoint of securing the load capacity, it is 700 (Rockwell C hardness HRC60) or more, preferably 710 (Rockwell C hardness HRC60.6) or more, from the viewpoint of suppressing embrittlement and securing sufficient toughness. , 800 (Rockwell C hardness HRC64) or less, preferably 790 (Rockwell C hardness HRC63.6) or less.
なお、本明細書において、「最大直交せん断応力発生深さ」は、転がり摺動部材の内部に生じる直交せん断応力が最大となる深さをいう。前記最大直交せん断応力発生深さは、通常、転がり摺動部材の種類、転がり摺動部材の形状、転がり摺動部材の使用条件等によって異なるが、転がり軸受を構成する転動体の大きさから決定することができる。 In this specification, the “maximum orthogonal shear stress generation depth” refers to the depth at which the orthogonal shear stress generated inside the rolling sliding member is maximum. The maximum orthogonal shear stress generation depth usually depends on the type of the rolling sliding member, the shape of the rolling sliding member, the use conditions of the rolling sliding member, and the like, but is determined from the size of the rolling element constituting the rolling bearing. can do.
最大直交せん断応力発生深さは、通常、転動体の転がり摺動面から［転動体の直径Ｄの０．２〜２．５％］の深さである。ここで、「転動体の直径Ｄ」は、転動体が玉軸受の玉である場合、玉の直径を示し、転動体がころ軸受のころである場合、ころの大端径を示す。 The maximum orthogonal shear stress generation depth is usually a depth of [0.2 to 2.5% of the diameter D of the rolling element] from the rolling sliding surface of the rolling element. Here, "the diameter D of the rolling element" indicates the diameter of the ball when the rolling element is a ball of a ball bearing, and indicates the large end diameter of the roller when the rolling element is a roller of a roller bearing.
外内輪１０，２０の軌道部１１ａ，２１ａ及び玉３０それぞれの転がり摺動面から最大直交せん断応力発生深さの位置における残留オーステナイト量は、転動体の転動中の応力誘起マルテンサイト変態によって組織を強靭化し、転動疲労寿命を向上させる観点から、２５体積％以上、好ましくは２６体積％以上であり、転がり軸受に要求される最低限の硬さを得る観点から、５０体積％以下、好ましくは４９体積％以下である。 The amount of retained austenite at the position where the maximum orthogonal shear stress is generated from the rolling sliding surfaces of the raceways 11a, 21a and the balls 30 of the outer and inner rings 10, 20 is determined by the stress-induced martensitic transformation during rolling of the rolling element. Is 25 vol% or more, preferably 26 vol% or more, from the viewpoint of increasing the toughness and improving the rolling fatigue life, and 50 vol% or less, preferably from the viewpoint of obtaining the minimum hardness required for the rolling bearing. Is 49% by volume or less.
表面硬化層１０ａ２，２０ａ２，３０ａ２には、析出物粒子が存在している。なお、本明細書において、「析出物粒子」は、クロム炭化物からなる粒子、クロム炭窒化物からなる粒子、モリブデン炭化物からなる粒子、モリブデン炭窒化物からなる粒子、クロム−モリブデン複合炭化物からなる粒子及びクロム−モリブデン複合炭窒化物からなる粒子の総称を意味する。 Precipitate particles are present in the surface hardened layers 10a2, 20a2, and 30a2. In the present specification, "precipitate particles" are particles made of chromium carbide, particles made of chromium carbonitride, particles made of molybdenum carbide, particles made of molybdenum carbonitride, and particles made of chromium-molybdenum composite carbide. And chromium-molybdenum composite carbonitride.
外内輪１０，２０の軌道部１１ａ，２１ａ及び玉３０それぞれの転がり摺動面から最大直交せん断応力発生深さの位置において、前記析出物粒子の平均粒径は、前記位置において、析出強化により転がり軸受に要求される硬さを確保しつつ、応力誘起マルテンサイト変態による組織の強靭化を行なうために必要な残留オーステナイト量を確保する観点から、１μｍ以上、好ましくは１．５μｍ以上であり、前記位置での粗大な析出物粒子が起点となる内部起点はく離を防止する観点から、５μｍ以下、好ましくは４μｍ以下である。なお、前記析出物粒子の平均粒径は、顕微鏡観察下に、転がり摺動面から最大直交せん断応力発生深さの位置において、透過型電子顕微鏡によって取得した１μｍ×１μｍ範囲の視野に存在する析出物粒子のすべての粒径を測定し、得られた測定値から平均値を算出することによって求められた値である。 At the position of the maximum orthogonal shear stress generation depth from the rolling sliding surfaces of the raceway portions 11a, 21a of the outer and inner rings 10, 20 and the ball 30, the average particle size of the precipitate particles at the position is rolling by precipitation strengthening at the position. From the viewpoint of ensuring the amount of retained austenite necessary to strengthen the structure by stress-induced martensitic transformation while ensuring the hardness required for the bearing, 1 μm or more, preferably 1.5 μm or more, It is 5 μm or less, preferably 4 μm or less, from the viewpoint of preventing peeling of the internal origin where coarse precipitate particles at the position originate. The average particle size of the precipitate particles is such that the precipitates existing in the visual field of 1 μm × 1 μm range obtained by the transmission electron microscope at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface under the microscope observation. This is a value obtained by measuring all particle diameters of the material particles and calculating an average value from the obtained measured values.
外内輪１０，２０の軌道部１１ａ，２１ａ及び玉３０それぞれの転がり摺動面から最大直交せん断応力発生深さの位置において、前記析出物粒子の最近接粒子間距離は、前記位置での残留オーステナイトの応力誘起マルテンサイト変態を起こしやすくする観点から、１５μｍ以上、好ましくは１７μｍ以上であり、析出強化によって転がり摺動部材として十分な硬さを確保する観点から、２５μｍ以下、より好ましくは２３μｍ以下である。なお、前記析出物粒子の最近接粒子間距離は、前記析出物粒子の粒子間距離の最小値である。前記析出物粒子の粒子間距離（Ｌ）は、前記析出物粒子の平均粒径と、析出物粒子の粒子体積率とを用い、式（Ｉ）： At the position of the maximum orthogonal shear stress generation depth from the rolling sliding surfaces of the raceways 11a, 21a of the outer and inner rings 10, 20 and the ball 30, the distance between the closest particles of the precipitate particles is the residual austenite at the position. From the viewpoint of easily causing the stress-induced martensitic transformation of 15 μm or more, preferably 17 μm or more, from the viewpoint of securing sufficient hardness as a rolling sliding member by precipitation strengthening, 25 μm or less, more preferably 23 μm or less. is there. The distance between the closest particles of the precipitate particles is the minimum value of the distance between the particles of the precipitate particles. The interparticle distance (L) of the precipitate particles is calculated using the average particle diameter of the precipitate particles and the particle volume ratio of the precipitate particles, using the following formula (I):
（式中、Ｌは析出物粒子の粒子間距離、ｒは析出物粒子の平均粒径、ｆは析出物粒子の粒子体積率を示す）
にしたがって求めることができる。析出物粒子の粒子体積率は、画像解析により、１μｍ×１μｍの範囲の視野に存在する析出物粒子の面積率を算出することによって求めることができる。なお、前記面積率は、析出物粒子の形状を高さ１μｍの円柱と仮定することにより、体積率と同じものとして扱う。
(Where L is the distance between the precipitate particles, r is the average particle size of the precipitate particles, and f is the particle volume ratio of the precipitate particles)
Can be obtained according to The particle volume ratio of the precipitate particles can be determined by calculating the area ratio of the precipitate particles present in a visual field of 1 μm × 1 μm by image analysis. The area ratio is assumed to be the same as the volume ratio by assuming that the shape of the precipitate particles is a column having a height of 1 μm.
転がり軸受においては、転動体が転動する際に、転がり摺動部材の転がり摺動面ではなく、転がり摺動面よりも内部において、最も大きい直交せん断応力が発生してはく離が生じる。これに対し、外内輪１０，２０及び玉３０においては、転がり摺動面から最大直交せん断応力発生深さの位置におけるビッカース硬さＨｖが７００〜８００（ロックウェルＣ硬さＨＲＣが６０〜６４）、前記転がり摺動面から前記最大直交せん断応力発生深さの位置における残留オーステナイト量が２５〜５０体積％、前記位置における析出物粒子の平均粒径が１〜５μｍ、及び前記位置における前記析出物粒子の最近接粒子間距離が１５〜２５μｍである。そのため、外内輪１０，２０及び玉３０それぞれの転がり摺動面から最大直交せん断応力発生深さの位置の組織は、玉３０の転動に伴い、残留オーステナイトが応力誘起マルテンサイト変態を起こしやすい組織構造を有している。したがって、外内輪１０，２０及び玉３０によれば、玉軸受１において、玉３０が転動を開始した初期に、最大直交せん断応力が発生する深さの位置の硬さが向上し、組織が強靭化されるため、長い転動疲労寿命を確保することができる。 In a rolling bearing, when a rolling element rolls, the largest orthogonal shear stress is generated not inside the rolling sliding surface of the rolling sliding member but inside the rolling sliding surface, and peeling occurs. On the other hand, in the outer and inner rings 10, 20 and the ball 30, the Vickers hardness Hv at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 700 to 800 (Rockwell C hardness HRC is 60 to 64). The amount of retained austenite at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 25 to 50% by volume, the average particle size of the precipitate particles at the position is 1 to 5 μm, and the precipitate at the position The distance between the particles closest to each other is 15 to 25 μm. Therefore, the structure at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface of each of the outer and inner rings 10, 20 and the ball 30 is a structure in which the retained austenite is liable to undergo stress-induced martensitic transformation with the rolling of the ball 30. It has a structure. Therefore, according to the outer and inner rings 10, 20 and the ball 30, in the ball bearing 1, the hardness at the position where the maximum orthogonal shear stress occurs at the initial stage when the ball 30 starts rolling is improved, and the structure is improved. Since it is tough, a long rolling fatigue life can be secured.
外内輪１０，２０及び玉３０は、例えば、前記鋼材から形成された素形材を形成する前加工工程と、得られた素形材に対し、浸炭焼入れ処理又は浸炭窒化焼入れ処理を施し、中間素材を得る表面硬化処理工程と、得られた中間素材に仕上げ加工を施す仕上げ加工工程とを含む方法等によって得られる。以下、本実施形態に係る転がり摺動部材の製造方法の例として、外輪１０の製造方法を説明する。図２は本発明の一実施形態に係る転がり摺動部材である外輪の製造方法の各工程を示す工程図、図３は表面硬化処理工程における熱処理条件の一例を示す線図である。 The outer and inner rings 10 and 20 and the balls 30 are subjected to, for example, a pre-processing step of forming a shaped material formed from the steel material and carburizing and quenching and quenching of the obtained shaped material. It can be obtained by a method including a surface hardening treatment step of obtaining a material and a finishing step of finishing the obtained intermediate material. Hereinafter, a method of manufacturing the outer race 10 will be described as an example of a method of manufacturing the rolling sliding member according to the present embodiment. FIG. 2 is a process diagram showing each step of a method for manufacturing an outer race as a rolling sliding member according to one embodiment of the present invention, and FIG. 3 is a diagram showing an example of heat treatment conditions in a surface hardening process.
まず、前記鋼材から形成された軌道部１１ａ、端面１１ｂ、肩面１１ｃ及び外周面１１ｄに対応する部分を有する外輪１０の素形材１４を得る〔「前加工工程」、図２（ａ）参照〕。 First, the cast material 14 of the outer race 10 having portions corresponding to the raceway portion 11a, the end surface 11b, the shoulder surface 11c, and the outer peripheral surface 11d formed from the steel material is obtained ["Pre-processing step", see FIG. ].
つぎに、得られた素形材１４に対し、表面硬化処理を施す〔「表面硬化処理工程」、図２（ｂ）〕。表面硬化処理工程としては、例えば、浸炭焼入れ処理工程と焼戻し工程とを含む工程（図３（Ａ）参照）、浸炭窒化焼入れ処理工程と焼戻し工程とを含む工程（図３（Ｂ）参照）等が挙げられる。 Next, the obtained shaped material 14 is subjected to a surface hardening treatment (“a surface hardening process”, FIG. 2B). Examples of the surface hardening process include a process including a carburizing and quenching process and a tempering process (see FIG. 3A), a process including a carbonitriding and quenching process and a tempering process (see FIG. 3B), and the like. Is mentioned.
図３（ａ）に例示される表面硬化処理工程では、まず、素形材１４を、浸炭炉内で、カーボンポテンシャル１．１〜１．３の浸炭雰囲気下に、９００〜９５０℃の浸炭温度で３時間以上加熱保持して浸炭処理を行なった後、８４０〜８７０℃の焼入れ温度で１時間以内の焼入れ時間加熱保持し、つぎに、８０℃に油冷する（浸炭焼入れ処理工程）。その後、得られた素形材１４を１６０〜２００℃の焼戻し温度で０．５〜４時間保持して焼戻しを行なう（焼戻し工程）。 In the surface hardening process illustrated in FIG. 3A, first, the cast material 14 is placed in a carburizing furnace under a carburizing atmosphere having a carbon potential of 1.1 to 1.3 and a carburizing temperature of 900 to 950 ° C. After heating and holding for 3 hours or more to carry out carburizing, the steel is heated and held at a quenching temperature of 840 to 870 ° C for a quenching time of 1 hour or less, and then oil-cooled to 80 ° C (carburizing and quenching process step). Thereafter, the obtained shaped material 14 is kept at a tempering temperature of 160 to 200 ° C. for 0.5 to 4 hours to perform tempering (tempering step).
浸炭雰囲気のカーボンポテンシャルは、鋼材の表面層において、十分な炭素濃度を確保してマルテンサイト組織を生成させ、かつ十分な大きさの析出物を分散させることにより、十分な大きさの転がり摺動部材に適した硬さを確保するとともに、十分な量の残留オーステナイトを生成させて転動疲労寿命を向上させる観点から、好ましくは１．１以上、より好ましくは１．１５以上であり、はく離の起点となる粗大な析出物の形成を抑制し、転動疲労寿命を向上させる観点から、好ましくは１．３以下、より好ましくは１．２５以下である。 The carbon potential in the carburizing atmosphere is controlled to ensure a sufficient carbon concentration in the surface layer of the steel to generate a martensitic structure and to disperse a precipitate of a sufficient size to provide a sufficient amount of rolling and sliding. From the viewpoint of securing the hardness suitable for the member and improving the rolling fatigue life by generating a sufficient amount of retained austenite, it is preferably 1.1 or more, more preferably 1.15 or more. From the viewpoint of suppressing the formation of coarse precipitates serving as starting points and improving the rolling fatigue life, it is preferably 1.3 or less, more preferably 1.25 or less.
浸炭温度は、所定の熱処理性状を得るために必要な処理時間を短縮するのに適した拡散速度で鋼材中に炭素を拡散させ、生産コストを低減させる観点から、好ましくは９００℃以上、より好ましくは９１０℃以上であり、結晶粒の粗大化及び過剰浸炭組織の発生を抑制する観点から、好ましくは９５０℃以下、より好ましくは９４０℃以下である。 Carburizing temperature is preferably 900 ° C. or higher, more preferably 900 ° C. or more, from the viewpoint of diffusing carbon in steel at a diffusion rate suitable for shortening the processing time required to obtain a predetermined heat treatment property, and reducing production cost. Is 910 ° C. or higher, and is preferably 950 ° C. or lower, more preferably 940 ° C. or lower, from the viewpoint of suppressing coarsening of crystal grains and generation of excessive carburized structure.
浸炭時間は、鋼材の表面層において、十分な炭素濃度を確保して転がり摺動部材に適した硬さを確保する観点から、通常、好ましくは３時間以上である。なお、浸炭時間が長いほど、炭素は、鋼材中に広く分散し、より深い位置まで、転がり摺動部材に適した硬さを確保することができる。したがって、浸炭時間は、必要に応じて長くしてもよい。 The carburizing time is usually preferably 3 hours or more, from the viewpoint of securing a sufficient carbon concentration in the surface layer of the steel material and securing hardness suitable for a rolling sliding member. The longer the carburizing time, the more the carbon is dispersed in the steel material, and can secure a hardness suitable for the rolling sliding member to a deeper position. Therefore, the carburizing time may be increased if necessary.
焼入れ温度は、鋼材中に十分な量の炭素を固溶させることにより、十分な量の残留オーステナイト量を確保して転動疲労寿命を向上させる観点から、好ましくは８４０℃以上、より好ましくは８４５℃以上であり、鋼材のマトリクス中への炭素の固溶量を、十分な量の析出物を分散させるのに適した量に調整し、かつ残留オーステナイトの過剰な生成を抑制し、転動疲労寿命を向上させる観点から、好ましくは８７０℃以下、より好ましくは８６５℃以下である。 The quenching temperature is preferably 840 ° C. or higher, more preferably 845 ° C., from the viewpoint of securing a sufficient amount of retained austenite and improving the rolling fatigue life by dissolving a sufficient amount of carbon in the steel material. ° C or higher, and adjusts the amount of solid solution of carbon in the matrix of steel to an amount suitable for dispersing a sufficient amount of precipitates, and suppresses excessive generation of retained austenite, and reduces rolling fatigue. From the viewpoint of improving the life, the temperature is preferably 870 ° C or lower, more preferably 865 ° C or lower.
焼入れ温度での保持時間は、素形材全体の温度が所定の焼入れ温度になるために必要な時間以上であればよい。粗大な析出物の形成を抑制し、転がり摺動部材に適した靱性を確保する観点から、好ましくは１時間以下である。 The holding time at the quenching temperature need only be equal to or longer than the time required for the temperature of the entire shaped material to reach the predetermined quenching temperature. From the viewpoint of suppressing the formation of coarse precipitates and securing toughness suitable for a rolling sliding member, it is preferably 1 hour or less.
焼戻し温度は、転がり摺動部材に適した靱性を確保する観点から、好ましくは１６０℃以上、より好ましくは１７０℃以上であり、転がり摺動部材に適した硬さを確保する観点から、好ましくは２００℃以下、より好ましくは１９０℃以下である。 The tempering temperature is preferably 160 ° C. or more, more preferably 170 ° C. or more, from the viewpoint of securing toughness suitable for the rolling sliding member, and is preferably from the viewpoint of securing hardness suitable for the rolling sliding member. The temperature is 200 ° C or lower, more preferably 190 ° C or lower.
焼戻し時間は、転がり摺動部材に適した靱性を確保する観点から、好ましくは０．５時間以上、より好ましくは１時間以上であり、転がり摺動部材に適した硬さを確保するとともに、熱処理コストを低減させる観点から、好ましくは４時間以下、より好ましくは３時間以下である。なお、本明細書において、「焼戻し時間」とは、素形材が所定の温度に達した時点から空冷を開始するまでの時間をいう。 The tempering time is preferably 0.5 hours or more, more preferably 1 hour or more, from the viewpoint of securing toughness suitable for the rolling sliding member, and while ensuring hardness suitable for the rolling sliding member, From the viewpoint of cost reduction, it is preferably 4 hours or less, more preferably 3 hours or less. In addition, in this specification, "tempering time" means the time from when the cast material reaches a predetermined temperature to when air cooling is started.
一方、図３（ｂ）に例示される表面硬化処理工程では、素形材１４を、浸炭窒化炉内で、カーボンポテンシャル１．１〜１．３及びアンモニア濃度１〜３体積％の浸炭雰囲気下に、８６０〜８９０℃の浸炭窒化温度で３時間以上加熱保持して浸炭窒化処理を行なった後、８４０〜８７０℃の焼入れ温度で１時間以内の焼入れ時間加熱保持して焼入れを行なう。つぎに、焼入れ後の素形材１４を８０℃に油冷する。その後、得られた素形材１４を１６０〜２００℃の焼戻し温度で０．５〜４時間保持して焼戻しを行なう。 On the other hand, in the surface hardening process illustrated in FIG. 3B, the cast material 14 is placed in a carbonitriding furnace under a carburizing atmosphere having a carbon potential of 1.1 to 1.3 and an ammonia concentration of 1 to 3% by volume. Then, after performing carbonitriding by heating and holding at a carbonitriding temperature of 860 to 890 ° C. for 3 hours or more, quenching is performed by heating and holding at a quenching temperature of 840 to 870 ° C. for 1 hour or less. Next, the quenched shaped member 14 is oil-cooled to 80 ° C. Thereafter, the obtained shaped material 14 is tempered by holding it at a tempering temperature of 160 to 200 ° C. for 0.5 to 4 hours.
浸炭窒化雰囲気のカーボンポテンシャルは、浸炭雰囲気のカーボンポテンシャルと同様である。 The carbon potential in the carbonitriding atmosphere is the same as the carbon potential in the carburizing atmosphere.
浸炭窒化雰囲気のアンモニア濃度は、十分な大きさの析出物を分散させることにより、転がり摺動部材に適した硬さを確保する観点から、好ましくは１体積％以上、より好ましくは１．５体積％以上であり、はく離の起点となる粗大な析出物の形成を抑制し、転動疲労寿命を向上させる観点から、好ましくは３体積％以下、より好ましくは２．５体積％以下である。 The ammonia concentration in the carbonitriding atmosphere is preferably 1% by volume or more, more preferably 1.5% by volume, from the viewpoint of dispersing precipitates of a sufficient size to secure hardness suitable for a rolling sliding member. % Or more, and from the viewpoint of suppressing the formation of coarse precipitates serving as starting points of peeling and improving the rolling fatigue life, is preferably 3% by volume or less, more preferably 2.5% by volume or less.
浸炭窒化温度は、所定の熱処理性状を得るために必要な処理時間を短縮するのに適した拡散速度で鋼材中に炭素及び窒素を拡散させ、生産コストを低減させる観点から、好ましくは８６０℃以上、より好ましくは８６５℃以上であり、結晶粒の粗大化及び過剰浸炭組織の発生を抑制する観点から、好ましくは８９０℃以下、より好ましくは８８５℃以下である。 The carbonitriding temperature is preferably 860 ° C. or higher from the viewpoint of diffusing carbon and nitrogen into the steel at a diffusion rate suitable for shortening the processing time required to obtain a predetermined heat treatment property, and reducing the production cost. 865 ° C. or higher, and preferably 890 ° C. or lower, more preferably 885 ° C. or lower, from the viewpoint of suppressing the coarsening of crystal grains and the generation of excessive carburizing structure.
浸炭窒化時間は、鋼材の表面層において、十分な炭素濃度及び窒素濃度を確保して転がり摺動部材に適した硬さを確保する観点から、通常、好ましくは３時間以上である。なお、浸炭窒化時間が長いほど、炭素及び窒素は、鋼材中に広く分散し、より深い位置まで、転がり摺動部材に適した硬さを確保することができる。したがって、浸炭窒化時間は、必要に応じて長くしてもよい。 The carbonitriding time is usually preferably 3 hours or more from the viewpoint of securing a sufficient carbon concentration and a nitrogen concentration in the surface layer of the steel material to secure hardness suitable for a rolling sliding member. Note that, as the carbonitriding time is longer, carbon and nitrogen are more widely dispersed in the steel material, and the hardness suitable for the rolling sliding member can be secured up to a deeper position. Therefore, the carbonitriding time may be increased if necessary.
焼入れ温度は、鋼材中に十分な量の炭素及び窒素を固溶させることにより、十分な量の残留オーステナイト量を確保して転動疲労寿命を向上させる観点から、好ましくは８４０℃以上、より好ましくは８４５℃以上であり、鋼材のマトリクス中への炭素の固溶量を、十分な量の析出物を分散させるのに適した量に調整し、かつ残留オーステナイトの過剰な生成を抑制し、転動疲労寿命を向上させる観点から、好ましくは８７０℃以下、より好ましくは８６５℃以下である。 The quenching temperature is preferably 840 ° C. or more, more preferably 840 ° C. or more, from the viewpoint of securing a sufficient amount of retained austenite and improving the rolling fatigue life by dissolving a sufficient amount of carbon and nitrogen in the steel material. Is 845 ° C. or higher, so that the amount of solid solution of carbon in the matrix of the steel material is adjusted to an amount suitable for dispersing a sufficient amount of precipitates, and excessive generation of retained austenite is suppressed. From the viewpoint of improving the dynamic fatigue life, the temperature is preferably 870 ° C or lower, more preferably 865 ° C or lower.
焼入れ温度での保持時間は、素形材全体の温度が所定の焼入れ温度になるために必要な時間以上であればよい。粗大な析出物の形成を抑制し、転がり摺動部材に適した靱性を確保する観点から、好ましくは１時間以下である。 The holding time at the quenching temperature need only be equal to or longer than the time required for the temperature of the entire shaped material to reach the predetermined quenching temperature. From the viewpoint of suppressing the formation of coarse precipitates and securing toughness suitable for a rolling sliding member, it is preferably 1 hour or less.
焼戻し温度は、転がり摺動部材に適した靱性を確保する観点から、好ましくは１６０℃以上、より好ましくは１７０℃以上であり、転がり摺動部材に適した硬さを確保する観点から、好ましくは２００℃以下、より好ましくは１９０℃以下である。 The tempering temperature is preferably 160 ° C. or more, more preferably 170 ° C. or more, from the viewpoint of securing toughness suitable for the rolling sliding member, and is preferably from the viewpoint of securing hardness suitable for the rolling sliding member. The temperature is 200 ° C or lower, more preferably 190 ° C or lower.
焼戻し時間は、転がり摺動部材に適した靱性を確保する観点から、好ましくは０．５時間以上、より好ましくは１時間以上であり、転がり摺動部材に適した硬さを確保するとともに、熱処理コストを低減させる観点から、好ましくは４時間以下、より好ましくは３時間以下である。 The tempering time is preferably 0.5 hours or more, more preferably 1 hour or more, from the viewpoint of securing toughness suitable for the rolling sliding member, and while ensuring hardness suitable for the rolling sliding member, From the viewpoint of cost reduction, it is preferably 4 hours or less, more preferably 3 hours or less.
つぎに、焼戻し工程後の中間素材に、軌道部１１ａ、端面１１ｂ及び外周面１１ｄそれぞれを形成する部分に対して、研磨仕上げ加工、必要に応じ、超仕上げ加工を施すことにより、転がり摺動部材（外輪１０）を得る〔「仕上げ加工」、図２（ｃ）参照〕。 Next, the intermediate material after the tempering step is subjected to polishing finishing and, if necessary, super-finishing to portions forming the raceway portion 11a, the end surface 11b, and the outer peripheral surface 11d, so that the rolling sliding member is formed. (Outer ring 10) is obtained ["finishing", see FIG. 2 (c)].
つぎに、実施例等により、本発明の一実施形態に係る転がり摺動部材及びその製造方法の作用効果を検証する。 Next, working effects of the rolling sliding member and the method of manufacturing the rolling sliding member according to the embodiment of the present invention will be verified with examples and the like.
実施例１〜７及び比較例１〜１０
表１に示される代表的成分（残部鉄及び不可避不純物）を有する鋼材を所定形状に加工して、深溝玉軸受（軸受呼び番号６２０６）用外内輪及び玉それぞれの素形材を製造した。
Examples 1 to 7 and Comparative Examples 1 to 10
A steel material having the typical components shown in Table 1 (remainder iron and unavoidable impurities) was processed into a predetermined shape to produce an outer and inner ring for a deep groove ball bearing (bearing number 6206) and a raw material for each ball.
つぎに、得られた素形材に、熱処理を施した後、研磨仕上げを施し、実施例１〜７及び比較例１〜１０の深溝玉軸受を得た。実施例１〜７及び比較例１〜１０それぞれにおける熱処理条件を表２及び図４〜１５に示す。 Next, the obtained shaped material was subjected to a heat treatment and then polished to obtain deep groove ball bearings of Examples 1 to 7 and Comparative Examples 1 to 10. The heat treatment conditions in Examples 1 to 7 and Comparative Examples 1 to 10 are shown in Table 2 and FIGS.
図４に示される熱処理条件ａは、（ａ１）カーボンポテンシャル１．３の浸炭雰囲気下に素形材を９５０℃で５時間加熱（浸炭）した後、得られた素形材を８４０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ａ２）浸炭焼入れ後の素形材を２００℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment conditions a shown in FIG. 4 are as follows: (a1) After heating (carburizing) the shaped material at 950 ° C. for 5 hours in a carburizing atmosphere having a carbon potential of 1.3, the obtained shaped material is heated at 840 ° C. for 30 hours. For two minutes, followed by oil-cooling (quenching) to 80 ° C., and (a2) tempering by heating the shaped material after carburizing and quenching at 200 ° C. for 2 hours and then air-cooling. .
図５に示される熱処理条件ｂは、（ｂ１）カーボンポテンシャル１．３の浸炭雰囲気下に素形材を９５０℃で５時間加熱（浸炭）した後、得られた素形材を８４０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｂ２）浸炭焼入れ後の素形材を１６０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment conditions b shown in FIG. 5 are as follows: (b1) After heating (carburizing) the shaped material at 950 ° C. for 5 hours in a carburizing atmosphere with a carbon potential of 1.3, the obtained shaped material is heated at 840 ° C. for 30 hours. Minutes, then carburizing and quenching to oil-cooling (quenching) to 80 ° C., and (b2) tempering to heat the shaped material after carburizing and quenching at 160 ° C. for 2 hours and then air-cool. .
図６に示される熱処理条件ｃは、（ｃ１）カーボンポテンシャル１．３の浸炭雰囲気下に素形材を９００℃で５時間加熱（浸炭）した後、得られた素形材を８４０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｃ２）浸炭焼入れ後の素形材を１６０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment condition c shown in FIG. 6 is as follows: (c1) After heating (carburizing) the cast material at 900 ° C. for 5 hours in a carburizing atmosphere having a carbon potential of 1.3, the obtained cast material is heated at 840 ° C. for 30 hours. For two minutes, then carburizing and quenching to oil-cool (quenching) to 80 ° C, and (c2) tempering to heat the shaped material after carburizing and quenching at 160 ° C for 2 hours and then air-cool. .
図７に示される熱処理条件ｄは、（ｄ１）カーボンポテンシャル１．１の浸炭雰囲気下に素形材を９５０℃で５時間加熱（浸炭）した後、得られた素形材を８６０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｄ２）浸炭焼入れ後の素形材を１６０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment conditions d shown in FIG. 7 are as follows: (d1) After heating (carburizing) the shaped material at 950 ° C. for 5 hours in a carburizing atmosphere having a carbon potential of 1.1, the obtained shaped material is heated at 860 ° C. for 30 hours. For two minutes, then carburizing and quenching to oil-cool (quenching) to 80 ° C., and (d2) tempering to heat the shaped material after carburizing and quenching at 160 ° C. for 2 hours and then air-cool. .
図８に示される熱処理条件ｅは、（ｅ１）カーボンポテンシャル１．３の浸炭雰囲気下に素形材を９３０℃で５時間加熱（浸炭）した後、得られた素形材を８４０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｅ２）浸炭焼入れ後の素形材を１６０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment condition e shown in FIG. 8 is as follows: (e1) After heating (carburizing) the cast material at 930 ° C. for 5 hours in a carburizing atmosphere having a carbon potential of 1.3, the obtained cast material is heated at 840 ° C. for 30 hours. For two minutes, followed by oil-cooling (quenching) to 80 ° C., and (e2) tempering by heating the shaped material after carburizing and quenching at 160 ° C. for 2 hours and then air-cooling. .
図９に示される熱処理条件ｆは、（ｆ１）カーボンポテンシャル１．２の浸炭雰囲気下に素形材を９５０℃で５時間加熱（浸炭）した後、得られた素形材を８７０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｆ２）浸炭焼入れ後の素形材を１６０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment conditions f shown in FIG. 9 are as follows: (f1) After heating the formed material at 950 ° C. for 5 hours in a carburizing atmosphere having a carbon potential of 1.2 for 5 hours, the obtained formed material is heated at 870 ° C. for 30 hours. Minutes, then oil-cooling (quenching) to 80 ° C., and (f2) tempering by heating the shaped material after carburizing and quenching at 160 ° C. for 2 hours, followed by air cooling. .
図１０に示される熱処理条件ｇは、（ｇ１）カーボンポテンシャル１．３の浸炭雰囲気下に素形材を９５０℃で５時間加熱（浸炭）した後、得られた素形材を８７０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｇ２）浸炭焼入れ後の素形材を１６０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment conditions g shown in FIG. 10 are as follows: (g1) After heating (carburizing) the shaped material at 950 ° C. for 5 hours in a carburizing atmosphere having a carbon potential of 1.3, the obtained shaped material was heated at 870 ° C. for 30 hours. For two minutes, followed by carburizing and quenching to oil-cool (quenching) to 80 ° C., and (g2) tempering by heating the shaped material after carburizing and quenching at 160 ° C. for 2 hours and then air-cooling. .
図１１に示される熱処理条件ｈは、（ｈ１）カーボンポテンシャル１．３の浸炭雰囲気下に素形材を９５０℃で５時間加熱（浸炭）した後、得られた素形材を８６０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｈ２）浸炭焼入れ後の素形材を８４０℃で２時間加熱し、８０℃まで油冷する２次焼入れと、（ｈ３）２次焼入れ後の素形材を１６０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment conditions h shown in FIG. 11 are as follows: (h1) After heating the formed material at 950 ° C. for 5 hours in a carburizing atmosphere with a carbon potential of 1.3 (carburizing), the obtained formed material is heated at 860 ° C. for 30 hours. For 2 minutes, then carburizing and quenching to oil-cool (quenching) to 80 ° C, and (h2) secondary quenching to heat the shaped material after carburizing and quenching at 840 ° C for 2 hours and oil-cooling to 80 ° C, (H3) This is a condition in which the shaped material after the secondary quenching is heated at 160 ° C. for 2 hours, and then tempered by air cooling.
図１２に示される熱処理条件ｉは、（ｉ１）カーボンポテンシャル１．３の浸炭雰囲気下に素形材を９５０℃で５時間加熱（浸炭）した後、得られた素形材を８８０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｉ２）浸炭焼入れ後の素形材を１６０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment condition i shown in FIG. 12 is as follows: (i1) After heating (carburizing) the shaped material at 950 ° C. for 5 hours in a carburizing atmosphere with a carbon potential of 1.3, the obtained shaped material is heated at 880 ° C. for 30 hours. For 1 minute, then oil-cooled (quenched) to 80 ° C., and (i2) tempered by heating the shaped material after carburizing and quenching at 160 ° C. for 2 hours and then air-cooling. .
図１３に示される熱処理条件ｊは、（ｊ１）カーボンポテンシャル１．１の浸炭雰囲気下に素形材を９５０℃で５時間加熱（浸炭）した後、得られた素形材を８３０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｊ２）浸炭焼入れ後の素形材を１６０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment condition j shown in FIG. 13 is as follows: (j1) After the shaped material is heated (carburized) at 950 ° C. for 5 hours in a carburizing atmosphere with a carbon potential of 1.1, the obtained shaped material is heated at 830 ° C. for 30 hours. For 1 minute, then oil-cooled (quenched) to 80 ° C., and (j2) tempered by heating the shaped material after carburizing and quenching at 160 ° C. for 2 hours and then air-cooling. .
図１４に示される熱処理条件ｋは、（ｋ１）カーボンポテンシャル１．３の浸炭雰囲気下に素形材を９５０℃で５時間加熱（浸炭）した後、得られた素形材を８４０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｋ２）浸炭焼入れ後の素形材を２２０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment conditions k shown in FIG. 14 are as follows: (k1) After heating (carburizing) the shaped material at 950 ° C. for 5 hours in a carburizing atmosphere with a carbon potential of 1.3, the obtained shaped material was heated at 840 ° C. for 30 hours. For two minutes, then carburizing and quenching to oil-cool (quenching) to 80 ° C., and (k2) tempering to heat the shaped material after carburizing and quenching at 220 ° C. for 2 hours and then air-cool. .
図１５に示される熱処理条件ｌは、（ｌ１）カーボンポテンシャル１．３の浸炭雰囲気下に素形材を９５０℃で５時間加熱（浸炭）した後、得られた素形材を８４０℃で３０分間加熱し、つぎに、８０℃まで油冷（焼入れ）する浸炭焼入れと、（ｌ２）浸炭焼入れ後の素形材を１５０℃で２時間加熱し、その後、空冷する焼戻しとを行なう条件である。 The heat treatment conditions 1 shown in FIG. 15 are as follows: (11) After heating (carburizing) the shaped material at 950 ° C. for 5 hours in a carburizing atmosphere with a carbon potential of 1.3, the obtained shaped material was heated at 840 ° C. for 30 hours. For 1 minute, then oil-cooled (quenched) to 80 ° C., and (12) tempered by heating the shaped material after carburizing and quenching at 150 ° C. for 2 hours and then air-cooling. .
試験例１
実施例１〜７及び比較例１〜１０で得られた深溝玉軸受に用いられた外内輪について、転がり摺動面から０．１ｍｍの深さ（最大直交せん断応力発生深さ）の位置でのビッカース硬さＨｖ、転がり摺動面から０．１ｍｍの深さの位置における残留オーステナイト量、転がり摺動面から０．１ｍｍの深さの位置における析出物粒子の平均粒径、転がり摺動面から０．１ｍｍの深さの位置における析出物粒子の最近接粒子間距離及び転動疲労寿命（Ｌ10寿命）を調べた。
Test example 1
Regarding the outer and inner rings used in the deep groove ball bearings obtained in Examples 1 to 7 and Comparative Examples 1 to 10, the outer and inner rings at a depth of 0.1 mm (the maximum orthogonal shear stress generation depth) from the rolling sliding surface. Vickers hardness Hv, amount of retained austenite at a depth of 0.1 mm from rolling sliding surface, average particle size of precipitate particles at a depth of 0.1 mm from rolling sliding surface, from rolling sliding surface It was examined nearest distance between particles and the rolling fatigue life of the dispersoids in the depth of the position of 0.1 mm (L 10 life).
ビッカース硬さＨｖは、実施例１〜７及び比較例１〜１０で得られた外内輪を転がり摺動面から深さ方向に切断した後、ＪＩＳ Ｚ ２２４４に記載の方法にしたがい、転がり摺動面から０．１ｍｍの深さの位置に圧子をあて、ビッカース硬さ試験機を用いて測定した。 The Vickers hardness Hv was determined by cutting the outer and inner races obtained in Examples 1 to 7 and Comparative Examples 1 to 10 from the rolling sliding surface in the depth direction, and then rolling according to the method described in JIS Z 2244. An indenter was applied to a position at a depth of 0.1 mm from the surface, and measurement was performed using a Vickers hardness tester.
残留オーステナイト量は、実施例１〜７及び比較例１〜１０で得られた外内輪の転がり摺動面から０．１ｍｍの深さの位置において、Ｘ線回折法により、α相（マルテンサイト）とγ相（オーステナイト）との積分強度の比を算出することによって調べた。 The amount of retained austenite was determined by the X-ray diffraction method at the position of a depth of 0.1 mm from the rolling sliding surface of the outer and inner rings obtained in Examples 1 to 7 and Comparative Examples 1 to 10 by α-phase (martensite). It was examined by calculating the ratio of the integrated intensity of the γ phase (austenite) to the γ phase.
析出物粒子の平均粒径は、顕微鏡観察下に、実施例１〜７及び比較例１〜１０で得られた外内輪の転がり摺動面から０．１ｍｍの位置において、透過型電子顕微鏡によって取得した１μｍ×１μｍ範囲の視野に存在する析出物粒子のすべての粒径を測定し、得られた測定値から平均値を算出することによって求めた。 The average particle diameter of the precipitate particles is obtained by a transmission electron microscope at a position of 0.1 mm from the rolling sliding surface of the outer and inner rings obtained in Examples 1 to 7 and Comparative Examples 1 to 10 under microscope observation. It was determined by measuring all the particle sizes of the precipitate particles present in the visual field in the range of 1 μm × 1 μm, and calculating an average value from the measured values.
析出物粒子の最近接粒子間距離は、前記析出物粒子の粒子間距離の最小値である。前記析出物粒子の粒子間距離は、前記析出物粒子の平均粒径と、析出物粒子の粒子体積率とを用い、式（Ｉ）にしたがって求めた。析出物粒子の粒子体積率は、画像解析により、１μｍ×１μｍの範囲の視野に存在する析出物粒子の面積率を算出することによって求めた。なお、前記面積率は、析出物粒子の形状を高さ１μｍの円柱と仮定することにより、体積率と同じものとして扱った。 The distance between the closest particles of the precipitate particles is the minimum value of the distance between the particles of the precipitate particles. The distance between the precipitate particles was determined according to the formula (I) using the average particle size of the precipitate particles and the particle volume ratio of the precipitate particles. The particle volume ratio of the precipitate particles was determined by calculating the area ratio of the precipitate particles present in a visual field of 1 μm × 1 μm by image analysis. The area ratio was treated as the same as the volume ratio by assuming that the shape of the precipitate particles was a column having a height of 1 μm.
転動疲労寿命は、実施例１〜７及び比較例１〜１０で得られた深溝玉軸受を用いて表３に示される条件で転動疲労寿命試験を行ない、その結果から求められる１０％破損確率を示すＬ10寿命を調べることによって評価した。１０％破損確率は、転動疲労試験の結果をワイブル確率紙上にプロットすることによって求めた。 The rolling fatigue life was determined by performing a rolling fatigue life test under the conditions shown in Table 3 using the deep groove ball bearings obtained in Examples 1 to 7 and Comparative Examples 1 to 10, and obtaining 10% damage from the results. was evaluated by examining the L 10 life indicates the probability. The 10% failure probability was determined by plotting the results of the rolling fatigue test on Weibull probability paper.
実施例１〜７及び比較例１〜１０それぞれで得られた外内輪について、転がり摺動面から０．１ｍｍの深さ（最大直交せん断応力発生深さ）の位置でのビッカース硬さＨｖ、転がり摺動面から０．１ｍｍの深さの位置における残留オーステナイト量、転がり摺動面から０．１ｍｍの深さの位置における析出物粒子の平均粒径、転がり摺動面から０．１ｍｍの深さの位置における析出物粒子の最近接粒子間距離及び転動疲労寿命（Ｌ10寿命）を調べた結果を表４に示す。また、試験例１において、ビッカース硬さとＬ10寿命との関係を調べた結果を図１６、残留オーステナイト量とＬ10寿命との関係を調べた結果を図１７、析出物粒子の粒子間距離とＬ10寿命との関係を調べた結果を図１８、析出物粒子の平均粒径とＬ10寿命との関係を調べた結果を図１９に示す。図中、黒丸は実施例で得られた深溝玉軸受を用いた場合の結果、白三角は比較例で得られた深溝玉軸受を用いた場合の結果を示す。なお、外内輪及び玉は、すべて同じ熱処理条件で処理されたものであり、熱処理後の研磨仕上げ時の取り代が同じである外輪と内輪とは、熱処理性状が互いに同じになる。そこで、表４の「深さｚ０位置での外内輪の熱処理性状」の欄には、代表的な結果として内輪の結果を示す。 Regarding the outer and inner rings obtained in Examples 1 to 7 and Comparative Examples 1 to 10, respectively, Vickers hardness Hv and rolling at a depth of 0.1 mm (maximum orthogonal shear stress generation depth) from the rolling sliding surface. Amount of retained austenite at a depth of 0.1 mm from the sliding surface, average particle size of precipitate particles at a depth of 0.1 mm from the rolling sliding surface, depth of 0.1 mm from the rolling sliding surface result of examining the nearest distance between particles and the rolling fatigue life (L 10 life) shown in Table 4 of the precipitate particles in position. Further, in Test Example 1, Fig. 17 the results of results of examining the relationship between Vickers hardness and L 10 life was examined 16, the relationship between the amount of residual austenite and L 10 life, and the interparticle distance of a precipitate particles Figure 18 the results of examining the relationship between the L 10 life, the results of examining the relationship between the average particle diameter and L 10 life of dispersoids 19. In the figure, black circles show the results when the deep groove ball bearing obtained in the example was used, and white triangles show the results when the deep groove ball bearing obtained in the comparative example was used. Note that the outer and inner rings and the balls are all processed under the same heat treatment conditions, and the outer ring and the inner ring having the same allowance for polishing and finishing after the heat treatment have the same heat treatment properties. Therefore, the column of "outside the inner ring of the heat treatment properties of a depth z 0 position" in Table 4 shows the inner ring of the resulting representative result.
表４、図１６〜図１９に示された結果から、実施例１〜７で得られた外内輪においては、前記ビッカース硬さＨｖが７０１．６〜７９０．８、前記残留オーステナイト量が２６〜４９体積％、前記析出物粒子の平均粒径が１５．７〜２３．８μｍ、前記析出物粒子の最近接粒子間距離が１．３〜４μｍであることがわかる。また、実施例１〜７で得られた外内輪の転動疲労寿命（Ｌ10寿命）は、１８００時間を超えていることがわかる。 From the results shown in Table 4 and FIGS. 16 to 19, in the outer and inner rings obtained in Examples 1 to 7, the Vickers hardness Hv was 701.6 to 790.8, and the amount of retained austenite was 26 to 49% by volume, the average particle diameter of the precipitate particles is 15.7 to 23.8 μm, and the distance between the closest particles of the precipitate particles is 1.3 to 4 μm. Further, the rolling fatigue life (L 10 life) of the outer inner ring obtained in Examples 1-7, it can be seen that beyond 1800 hours.
これに対し、比較例１で得られた外内輪においては、前記ビッカース硬さＨｖ及び残留オーステナイト量は、実施例１〜７で得られた外内輪と同様の範囲であるが、前記析出物粒子の平均粒径及び当該析出物粒子の粒子間距離が、実施例１〜７で得られた外内輪における前記析出物粒子の平均粒径及び当該析出物粒子の粒子間距離の最小値よりも小さいことがわかる。 On the other hand, in the outer and inner rings obtained in Comparative Example 1, the Vickers hardness Hv and the amount of retained austenite are in the same range as the outer and inner rings obtained in Examples 1 to 7, but the precipitate particles Is smaller than the average particle diameter of the precipitate particles in the outer and inner rings obtained in Examples 1 to 7 and the minimum value of the interparticle distance of the precipitate particles. You can see that.
また、比較例２で得られた外内輪においては、前記ビッカース硬さＨｖ、残留オーステナイト量及び析出物粒子の粒子間距離は、実施例１〜７で得られた外内輪と同様の範囲であるが、前記析出物粒子の平均粒径が、実施例１〜７で得られた外内輪における前記析出物粒子の平均粒径の最小値よりも小さいことがわかる。一方、比較例３で得られた外内輪においては、前記ビッカース硬さＨｖ、残留オーステナイト量及び析出物粒子の粒子間距離は、実施例１〜７で得られた外内輪と同様の範囲であるが、前記析出物粒子の平均粒径が、実施例１〜７で得られた外内輪における前記析出物粒子の平均粒径の最大値よりも大きいことがわかる。 In the outer and inner rings obtained in Comparative Example 2, the Vickers hardness Hv, the amount of retained austenite, and the interparticle distance of the precipitate particles are in the same ranges as the outer and inner rings obtained in Examples 1 to 7. However, it can be seen that the average particle size of the precipitate particles is smaller than the minimum value of the average particle size of the precipitate particles in the outer and inner rings obtained in Examples 1 to 7. On the other hand, in the outer and inner rings obtained in Comparative Example 3, the Vickers hardness Hv, the amount of retained austenite, and the interparticle distance of the precipitate particles are in the same ranges as the outer and inner rings obtained in Examples 1 to 7. However, it can be seen that the average particle size of the precipitate particles is larger than the maximum average particle size of the precipitate particles in the outer and inner rings obtained in Examples 1 to 7.
さらに、比較例４〜６で得られた外内輪においては、前記ビッカース硬さＨｖ、残留オーステナイト量及び析出物粒子の平均粒径は、実施例１〜７で得られた外内輪と同様の範囲であるが、前記析出物粒子の粒子間距離が、実施例１〜７で得られた外内輪における前記析出物粒子の粒子間距離の最小値よりも小さいことがわかる。 Furthermore, in the outer and inner rings obtained in Comparative Examples 4 to 6, the Vickers hardness Hv, the amount of retained austenite, and the average particle size of the precipitate particles are in the same ranges as those of the outer and inner rings obtained in Examples 1 to 7. However, it can be seen that the interparticle distance of the precipitate particles is smaller than the minimum value of the interparticle distance of the precipitate particles in the outer and inner rings obtained in Examples 1 to 7.
また、比較例７で得られた外内輪においては、前記ビッカース硬さＨｖ、析出物粒子の平均粒径及び当該析出物粒子の粒子間距離は、実施例１〜７で得られた外内輪と同様の範囲であるが、前記残留オーステナイト量が、実施例１〜７で得られた外内輪における前記残留オーステナイト量の最大値よりも大きいことがわかる。一方、比較例８で得られた外内輪においては、前記ビッカース硬さＨｖ、析出物粒子の平均粒径及び当該析出物粒子の粒子間距離は、実施例１〜７で得られた外内輪と同様の範囲であるが、前記残留オーステナイト量が、実施例１〜７で得られた外内輪における前記残留オーステナイト量の最小値よりも小さいことがわかる。 In the outer and inner races obtained in Comparative Example 7, the Vickers hardness Hv, the average particle size of the precipitate particles and the interparticle distance of the precipitate particles are the same as those of the outer and inner races obtained in Examples 1 to 7. Although it is in the same range, it can be seen that the amount of retained austenite is larger than the maximum value of the amount of retained austenite in the outer and inner rings obtained in Examples 1 to 7. On the other hand, in the outer and inner rings obtained in Comparative Example 8, the Vickers hardness Hv, the average particle diameter of the precipitate particles and the interparticle distance of the precipitate particles are the same as those of the outer and inner rings obtained in Examples 1 to 7. Although within the same range, it can be seen that the amount of retained austenite is smaller than the minimum value of the amount of retained austenite in the outer and inner rings obtained in Examples 1 to 7.
さらに、比較例９で得られた外内輪においては、前記残留オーステナイト量、析出物粒子の平均粒径及び当該析出物粒子の粒子間距離は、実施例１〜７で得られた外内輪と同様の範囲であるが、前記ビッカース硬さＨｖが、実施例１〜７で得られた外内輪における前記ビッカース硬さＨｖの最小値よりも小さいことがわかる。一方、比較例１０で得られた外内輪においては、前記残留オーステナイト量、析出物粒子の平均粒径及び当該析出物粒子の粒子間距離は、実施例１〜７で得られた外内輪と同様の範囲であるが、前記ビッカース硬さＨｖが、実施例１〜７で得られた外内輪における前記ビッカース硬さＨｖの最大値よりも大きいことがわかる。 Furthermore, in the outer and inner rings obtained in Comparative Example 9, the amount of retained austenite, the average particle size of the precipitate particles, and the interparticle distance of the precipitate particles are the same as those of the outer and inner rings obtained in Examples 1 to 7. It can be seen that the Vickers hardness Hv is smaller than the minimum value of the Vickers hardness Hv in the outer and inner rings obtained in Examples 1 to 7. On the other hand, in the outer and inner rings obtained in Comparative Example 10, the residual austenite amount, the average particle size of the precipitate particles, and the interparticle distance of the precipitate particles are the same as those of the outer and inner rings obtained in Examples 1 to 7. It can be seen that the Vickers hardness Hv is larger than the maximum value of the Vickers hardness Hv in the outer and inner rings obtained in Examples 1 to 7.
また、比較例１〜１０で得られた外内輪の転動疲労寿命（Ｌ10寿命）は、１０００時間未満であることがわかる。 Further, it can be seen that the rolling fatigue life (L10 life) of the outer and inner rings obtained in Comparative Examples 1 to 10 is less than 1000 hours.
したがって、これらの結果から、転がり摺動面から最大直交せん断応力発生深さの位置におけるビッカース硬さＨｖが７００〜８００（ロックウェルＣ硬さＨＲＣが６０〜６４）、前記転がり摺動面から前記最大直交せん断応力発生深さの位置における残留オーステナイト量が２５〜５０体積％、前記位置における析出物粒子の平均粒径が１〜５μｍ、当該位置における前記析出物粒子の最近接粒子間距離が１５〜２５μｍである転がり摺動部材を備える転がり軸受によれば、長い転動疲労寿命を確保することができることが示唆される。 Accordingly, from these results, the Vickers hardness Hv at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 700 to 800 (Rockwell C hardness HRC is 60 to 64), and the Vickers hardness Hv is 60 to 64 from the rolling sliding surface. The amount of retained austenite at the position of the maximum orthogonal shear stress generation depth is 25 to 50% by volume, the average particle size of the precipitate particles at the position is 1 to 5 μm, and the distance between the closest particles of the precipitate particles at the position is 15 It is suggested that a long rolling fatigue life can be ensured by a rolling bearing having a rolling sliding member of up to 25 μm.
試験例２
実施例６及び比較例１で得られた深溝玉軸受について、表３に示される条件で試験を行ない、試験例１と同様の操作を行ない、前記転がり摺動面から０．１ｍｍの深さの位置における残留オーステナイト量及び前記転がり摺動面から０．１ｍｍの深さの位置におけるビッカース硬さＨｖを所定の時間で試験を停止し、抜き取り測定を行なうことで経時的に調べた。
Test example 2
The deep groove ball bearings obtained in Example 6 and Comparative Example 1 were tested under the conditions shown in Table 3, and the same operation as in Test Example 1 was performed. The residual austenite amount at the position and the Vickers hardness Hv at a position at a depth of 0.1 mm from the rolling sliding surface were examined over time by stopping the test at a predetermined time and performing sampling measurement.
試験例２において、最大直交せん断応力発生深さ（深さｚ0）位置の残留オーステナイト量の経時的変化を調べた結果を図２０、最大直交せん断応力発生深さ（深さｚ0）位置のビッカース硬さＨｖの経時的変化を調べた結果を図２１に示す。図中、黒斜方形は実施例６で得られた深溝玉軸受を用いた場合の結果、白四角は比較例１で得られた深溝玉軸受を用いた場合の結果を示す。 In Test Example 2, the maximum orthogonal shear stress generating depth (depth z 0) Figure 20 the results of examining the time course of the residual austenite amount of the position, the maximum orthogonal shear stress generating depth (depth z 0) position FIG. 21 shows the result of examining the change over time of the Vickers hardness Hv. In the drawing, the black oblique square indicates the result when the deep groove ball bearing obtained in Example 6 was used, and the white square indicates the result when the deep groove ball bearing obtained in Comparative Example 1 was used.
図２０に示された結果から、実施例６で得られた深溝玉軸受は、比較例１で得られた深溝玉軸受に比べ、最大直交せん断応力発生深さ（深さｚ0）位置の残留オーステナイト量がより短い時間で減少することがわかる。また、図２１に示された結果から、実施例６で得られた深溝玉軸受は、比較例１で得られた深溝玉軸受に比べ、最大直交せん断応力発生深さ（深さｚ0）位置のビッカース硬さＨｖがより短い時間で増加することがわかる。これらの結果から、実施例６で得られた深溝玉軸受の転がり摺動面から最大直交せん断応力発生深さの位置では、比較例１で得られた深溝玉軸受の転がり摺動面から最大直交せん断応力発生深さの位置に比べ、転動体の転動に伴なう残留オーステナイトの応力誘起マルテンサイト変態が起こりやすいことが示唆される。 From the results shown in FIG. 20, the deep groove ball bearing obtained in Example 6 has a residual at the maximum orthogonal shear stress generation depth (depth z 0 ) as compared with the deep groove ball bearing obtained in Comparative Example 1. It can be seen that the amount of austenite decreases in a shorter time. Further, from the results shown in FIG. 21, the deep groove ball bearing obtained in Example 6 has a position of the maximum orthogonal shear stress generation depth (depth z 0 ) as compared with the deep groove ball bearing obtained in Comparative Example 1. It can be seen that the Vickers hardness Hv increases in a shorter time. From these results, at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface of the deep groove ball bearing obtained in Example 6, the maximum orthogonal shear stress was generated from the rolling sliding surface of the deep groove ball bearing obtained in Comparative Example 1. This suggests that stress-induced martensitic transformation of retained austenite accompanying rolling of rolling elements is more likely to occur than at the position where shear stress occurs.
したがって、転がり摺動面から最大直交せん断応力発生深さの位置におけるビッカース硬さＨｖが７００〜８００（ロックウェルＣ硬さが６０〜６４）、前記転がり摺動面から前記最大直交せん断応力発生深さの位置における残留オーステナイト量が２５〜５０体積％、前記位置における析出物粒子の平均粒径が１〜５μｍ、当該位置における前記析出物粒子の最近接粒子間距離が１５〜２５μｍである転がり摺動部材を備える転がり軸受は、前記位置における残留オーステナイトが応力誘起マルテンサイト変態を起こしやすい組織構造により、転動疲労寿命が向上していることが示唆される。 Therefore, the Vickers hardness Hv at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 700 to 800 (Rockwell C hardness is 60 to 64), and the maximum orthogonal shear stress generating depth is from the rolling sliding surface. The amount of the retained austenite at the position is 25 to 50% by volume, the average particle size of the precipitate particles at the position is 1 to 5 μm, and the distance between the closest particles of the precipitate particles at the position is 15 to 25 μm. It is suggested that the rolling bearing provided with the moving member has an improved rolling fatigue life due to the microstructure in which the retained austenite at the position tends to undergo stress-induced martensitic transformation.
１：玉軸受、１０：外輪、１０ａ：母材、１０ａ１：鋼材、１０ａ２：表面硬化層、２０：内輪、２０ａ：母材、２０ａ１：鋼材、２０ａ２：表面硬化層、３０：玉、３０ａ：母材、３０ａ１：鋼材、３０ａ２：表面硬化層 1: ball bearing, 10: outer ring, 10a: base material, 10a1: steel material, 10a2: surface hardened layer, 20: inner ring, 20a: base material, 20a1: steel material, 20a2: surface hardened layer, 30: ball, 30a: mother Material, 30a1: steel material, 30a2: hardened surface layer
Claims (2)
炭素０．１〜０．５質量％と、ケイ素０．３５質量％以下と、マンガン０．３〜１．０質量％と、クロム０．９〜２．５質量％と、モリブデン０．５〜０．９質量％とを含有し、残部が鉄及び不可避的不純物である鋼材の表面層が表面硬化層である母材からなり、
前記転がり摺動面から最大直交せん断応力発生深さの位置におけるビッカース硬さＨｖが７００〜８００であり、
前記転がり摺動面から前記最大直交せん断応力発生深さの位置における残留オーステナイト量が２５〜５０体積％であり、
前記転がり摺動面から前記最大直交せん断応力発生深さの位置における析出物粒子の平均粒径が１〜５μｍであり、
前記転がり摺動面から前記最大直交せん断応力発生深さの位置における前記析出物粒子の最近接粒子間距離が１５〜２５μｍである
ことを特徴とする転がり摺動部材。 A rolling sliding member having a rolling sliding surface relatively in contact with a mating member,
0.1 to 0.5% by mass of carbon, 0.35% by mass or less of silicon, 0.3 to 1.0% by mass of manganese, 0.9 to 2.5% by mass of chromium, 0.5 to 0.5% by mass of molybdenum 0.9% by mass, the balance being iron and a base material whose surface layer is a hardened layer of steel, which is an unavoidable impurity,
Vickers hardness Hv at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 700 to 800,
The residual austenite amount at the position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 25 to 50% by volume,
The average particle size of the precipitate particles at the position of the maximum orthogonal shear stress occurrence depth from the rolling sliding surface is 1 to 5 μm,
A rolling sliding member, wherein a distance between closest particles of the precipitate particles at a position of the maximum orthogonal shear stress generation depth from the rolling sliding surface is 15 to 25 μm.
前記外輪、内輪及び転動体のうちの少なくとも１つが、請求項１に記載の転がり摺動部材からなることを特徴とする転がり軸受。 A rolling bearing having an outer ring having a rolling sliding surface on an inner periphery, an inner ring having a rolling sliding surface on an outer periphery, and a plurality of rolling elements disposed between both rolling sliding surfaces of the outer inner ring. So,
A rolling bearing, wherein at least one of the outer ring, the inner ring, and the rolling element comprises the rolling sliding member according to claim 1.
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