JP3538900B2 - Rolling member - Google Patents

Rolling member

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Publication number
JP3538900B2
JP3538900B2 JP15387994A JP15387994A JP3538900B2 JP 3538900 B2 JP3538900 B2 JP 3538900B2 JP 15387994 A JP15387994 A JP 15387994A JP 15387994 A JP15387994 A JP 15387994A JP 3538900 B2 JP3538900 B2 JP 3538900B2
Authority
JP
Japan
Prior art keywords
mass
steel
less
rolling
machinability
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP15387994A
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Japanese (ja)
Other versions
JPH0820841A (en
Inventor
俊幸 星野
岩本  隆
聡 安本
明博 松崎
虔一 天野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Steel Corp
Original Assignee
JFE Steel Corp
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Priority to JP15387994A priority Critical patent/JP3538900B2/en
Publication of JPH0820841A publication Critical patent/JPH0820841A/en
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Description

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

【0001】[0001]

【産業上の利用分野】この発明は、ころ軸受、玉軸受と
いった転がり軸受に用いて好適な、加工性および転動疲
労寿命特性に優れた転動部材に関するものである。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling member which is suitable for rolling bearings such as roller bearings and ball bearings and has excellent workability and rolling fatigue life characteristics.

【0002】[0002]

【従来の技術】自動車ならびに産業機械等で用いられる
転がり軸受などの転動部材は、高炭素クロム軸受鋼2種
(JIS規格:SUJ2)が最も多く利用されている。
この鋼種は、0.95〜1.10mass%のCと0.90〜1.60mass%
のCrを含有していることから硬質であるため、まず球状
化焼鈍を行って加工性を向上させたのち、成形加工し、
その後に焼き入れ・焼き戻し処理を施すことによって転
がり軸受に必要な硬さを確保している。
2. Description of the Related Art As rolling members such as rolling bearings used in automobiles and industrial machines, two kinds of high carbon chromium bearing steel (JIS: SUJ2) are most often used.
This steel grade has 0.95 to 1.10 mass% C and 0.90 to 1.60 mass%.
Since it is hard because it contains Cr, it is first subjected to spheroidizing annealing to improve workability, then molded,
After that, a quenching / tempering process is performed to secure the hardness required for the rolling bearing.

【0003】これに対し、従来、特開平2−54739 号公
報では、主要成分が; C:0.45〜0.80重量%、Si:0.10〜2.0 重量%、Mn:0.
20〜2.0 重量%、P:0.015 重量%以下、S:0.015 重
量%以下、Cr:2.0 重量%以下、Al:0.015 〜0.060 重
量%、Ti:0.0020重量%以下、N:0.003 〜0.020 重量
%、O:0.0015重量%以下からなる軸受鋼を提案してい
る。この従来軸受鋼は、C含有量を低減することによっ
て、上述した球状化焼鈍処理を簡略化したり、あるいは
省略しても加工性の低下しない軸受鋼として開発された
ものである。しかしながら、最近では、こうした転動部
材の場合、加工形状が複雑化していることから、素材の
加工性の一層の改善ならびに製造コストの低減を図るこ
とが強く望まれている。
[0003] On the other hand, conventionally, in JP-A-2-54739, the main components are: C: 0.45 to 0.80% by weight, Si: 0.10 to 2.0% by weight, Mn: 0.
20 to 2.0% by weight, P: 0.015% by weight or less, S: 0.015% by weight or less, Cr: 2.0% by weight or less, Al: 0.015 to 0.060% by weight, Ti: 0.0020% by weight or less, N: 0.003 to 0.020% by weight, O: A bearing steel comprising 0.0015% by weight or less is proposed. This conventional bearing steel has been developed as a bearing steel in which the above-mentioned spheroidizing annealing treatment is simplified by reducing the C content or the workability does not decrease even if it is omitted. However, recently, in the case of such a rolling member, since the processing shape is complicated, it is strongly desired to further improve the workability of the material and reduce the manufacturing cost.

【0004】[0004]

【発明が解決しようとする課題】この発明の目的は、上
記の問題を有利に克服し、転動疲労寿命を損なうことな
く、冷間鍛造性あるいは切削加工といった加工性に優れ
た転動部材を提案することにある。
SUMMARY OF THE INVENTION It is an object of the present invention to provide a rolling member which advantageously overcomes the above-mentioned problems and has excellent workability such as cold forging or cutting without impairing the rolling fatigue life. It is to propose.

【0005】[0005]

【課題を解決するための手段】さて、発明者らは上記の
目的を実現すべく鋭意研究を行った結果、加工前に黒鉛
とフェライトを主体とする金属組織とすることによっ
て、被切削性あるいは冷間鍛造性が著しく向上すること
を見い出し、本発明に想到した。
Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, by forming a metal structure mainly composed of graphite and ferrite before working, the machinability or The present inventors have found that the cold forgeability is significantly improved, and have reached the present invention.

【0006】すなわち、本発明は、 (1)C:0.1 〜1.5 mass%、Si:0.5 〜2.0 mass%、M
n:0.1 〜2.5 mass%、N:0.0015〜0.0150mass%、
O:0.0020mass%以下を含有し、かつAl:0.01〜0.5 ma
ss%、B:0.0003〜0.0150mass%、Ti:0.005 〜0.05ma
ss%、REM :0.0005〜0.0200mass%、およびZr:0.005
〜0.2 mass%のうちから選ばれる1種または2種以上を
含有し、残部がFeおよび不可避的不純物からなる成分組
成を有すると共に、フェライトとセメンタイトの50%以
上が黒鉛化した組織からなるものであって、表層部には
残留オーステナイト量が10〜25%で硬度Hvが650以上の
硬化熱処理によって形成された硬化層を設けてなること
を特徴とする転動部材。 (2) 上記(1) に記載の転動部材の成分に加え、さらに、
Cr:1.0 mass%以下、Mo:1.0 mass%以下、V:0.5 ma
ss%以下、Nb:0.5 mass%以下、Ni:3.0 mass%以下、
Cu:3.0 mass%以下、Co:3.0 mass%以下のうちから選
ばれるいずれか1種または2種以上の元素を含むことを
特徴とする転動部材である。 (3) 上記(1) , (2) に記載の転動部材は、C:0.2 〜1.
3 mass%、Si:0.7 〜1.7 mass%、Mn:0.4 〜2.0 mass
%、N:0.0020〜0.0050mass%、O:0.0015mass%以下
を含有し、かつAl:0.020 〜0.050 mass%、B:0.0005
〜0.0025mass%、Ti:0.01〜0.03mass%、REM :0.0020
〜0.015 mass%、およびZr:0.01〜0.2 mass%の組成の
ものが好ましい転動部材と言える。 (4) なお、上記各転動部材の表面層に形成される硬化層
は、浸漬焼入れ処理、高周波焼入れ処理、浸炭焼入れ処
理または浸炭窒化焼入れ処理によって、部材表面を硬度
Hv 650以上にした改質層のことである。
That is, the present invention relates to (1) C: 0.1 to 1.5 mass%, Si: 0.5 to 2.0 mass%, M:
n: 0.1 to 2.5 mass%, N: 0.0015 to 0.0150 mass%,
O: contains 0.0020 mass% or less, and Al: 0.01 to 0.5 ma
ss%, B: 0.0003 to 0.0150 mass%, Ti: 0.005 to 0.05ma
ss%, REM: 0.0005-0.0200 mass%, and Zr: 0.005
And at least one selected from the group consisting of Fe and unavoidable impurities, and 50% or less of ferrite and cementite.
The upper part consists of a graphitized structure, and the surface layer
Retained austenite content is 10-25% and hardness Hv is 650 or more
A rolling member comprising a cured layer formed by a curing heat treatment . (2) In addition to the components of the rolling member described in the above (1), further,
Cr: 1.0 mass% or less, Mo: 1.0 mass% or less, V: 0.5 ma
ss% or less, Nb: 0.5 mass% or less, Ni: 3.0 mass% or less,
A rolling member characterized by containing one or more elements selected from Cu: 3.0 mass% or less and Co: 3.0 mass% or less. (3) The rolling member described in (1) and (2) above has a C: 0.2-1.
3 mass%, Si: 0.7 to 1.7 mass%, Mn: 0.4 to 2.0 mass
%, N: 0.0020 to 0.0050 mass%, O: 0.0015 mass% or less, and Al: 0.020 to 0.050 mass%, B: 0.0005
~ 0.0025mass%, Ti: 0.01 ~ 0.03mass%, REM: 0.0020
A rolling element having a composition of about 0.015 mass% and a composition of Zr: 0.01 to 0.2 mass% can be said to be preferable. ( 4 ) The hardened layer formed on the surface layer of each rolling member is hardened by immersion quenching, induction hardening, carburizing quenching or carbonitriding quenching.
Hv is 650 or higher.

【0007】[0007]

【作用】以下、本発明において部材の成分組成を上記の
範囲に限定した理由について説明する。 C:0.1 〜1.5 mass% Cは、黒鉛相を形成する上で不可欠なだけでなく、機械
部品の強度を確保する上でも重要な元素であるが、含有
量が0.1 mass%に満たないとその効果が小さく、一方1.
5 mass%を超えて添加してもその効果は飽和に達するの
で、0.1 〜1.5mass%の範囲に限定した。好ましくは 0.
2〜1.3 mass%の範囲とする。
The reason why the component composition of the member is limited to the above range in the present invention will be described below. C: 0.1 to 1.5 mass% C is not only indispensable for forming a graphite phase, but also an important element for securing the strength of mechanical parts, but if the content is less than 0.1 mass%, Less effective, while 1.
Since the effect reaches saturation even if it is added in excess of 5 mass%, it is limited to the range of 0.1 to 1.5 mass%. Preferably 0.
The range is 2 to 1.3 mass%.

【0008】Si:0.5 〜2.0 mass% Siは、溶製時の脱酸のために必要な元素であり、また鋼
中のセメンタイトを不安定にして黒鉛化を促進させる元
素としても有用であり、さらに焼もどし軟化抵抗を高
め、強度ならびに転動疲労寿命を向上させるので、積極
的に添加する。しかし、その含有量が0.5 mass%未満で
は上記の効果に乏しく、一方2.0 mass%を超えて含有さ
せても黒鉛化促進の効果は飽和に達し、また液相の発生
する温度領域が低下し、熱間圧延時の適正温度領域が狭
まるので、0.5 〜2.0 mass%の範囲とした。好ましくは
0.7〜1.7 mass%の範囲とする。
Si: 0.5 to 2.0 mass% Si is an element necessary for deoxidation during smelting, and is also useful as an element that destabilizes cementite in steel and promotes graphitization. Further, it is positively added to increase temper softening resistance and improve strength and rolling fatigue life. However, if the content is less than 0.5 mass%, the above effect is poor. On the other hand, if the content exceeds 2.0 mass%, the effect of promoting graphitization reaches saturation, and the temperature range in which a liquid phase is generated decreases, Since the appropriate temperature range during hot rolling narrows, the range is 0.5 to 2.0 mass%. Preferably
The range is 0.7 to 1.7 mass%.

【0009】Mn:0.1 〜2.5 mass% Mnは、鋼材の強度を確保する上で有効なだけでなく、脱
酸材としても有用な元素である。また、焼入れ性を高め
て強度ならびに転動疲労寿命の向上にも寄与する。しか
しながら、その含有量が0.1 mass%に満たないと、上記
の各作用に対する寄与が少なく、一方 2.5mass%を超え
て含有されると効果が飽和することに加えて靱性の劣化
を招くので、0.1 〜2.5 mass%の範囲に限定した。好ま
しくは 0.4〜2.0 mass%の範囲とする。
Mn: 0.1 to 2.5 mass% Mn is an element that is effective not only for securing the strength of the steel material but also useful as a deoxidizing material. In addition, it enhances hardenability and contributes to improvement in strength and rolling fatigue life. However, if the content is less than 0.1 mass%, the contribution to each of the above actions is small, while if it exceeds 2.5 mass%, the effect is saturated and the toughness is deteriorated. Limited to the range of ~ 2.5 mass%. Preferably, it is in the range of 0.4 to 2.0 mass%.

【0010】次に、本発明においては、転動部材として
の基本的な特性である黒鉛化を促進して転動疲労寿命を
向上させるという共通した作用効果を担う、B, Al, RE
M ,TiおよびZrを所定量添加する。これらの添加元素に
ついての限定理由を以下に説明する。
[0010] Next, in the present invention, B, Al, RE, which has a common effect of promoting graphitization, which is a basic property as a rolling member, and improving the rolling fatigue life, is provided.
Predetermined amounts of M, Ti and Zr are added. The reasons for limiting these additional elements will be described below.

【0011】Al:0.01〜0.5 mass% Alは、脱酸に寄与するだけでなく、黒鉛化を促進させる
有用元素でもある。即ち、Alの添加により鋼中に生成さ
れるAl酸化物は、BNの析出核となり、黒鉛の結晶化を
促進させる点でも効果が認められる。そこで本発明で
は、Alを積極的に添加するが、含有量が0.01mass%に満
たないとその添加効果に乏しく、一方 0.5mass%を超え
て含有させても黒鉛化促進効果が飽和する上、熱間変形
能の著しい低下を招くので、0.01〜0.5 mass%の範囲で
含有させるものとした。好ましくは0.02〜0.05mass%の
範囲がよい。
Al: 0.01 to 0.5 mass% Al not only contributes to deoxidation but also is a useful element for promoting graphitization. In other words, the effect is also recognized in that the Al oxide generated in the steel by the addition of Al becomes a nucleus for precipitation of BN and promotes the crystallization of graphite. Therefore, in the present invention, Al is positively added. However, if the content is less than 0.01 mass%, the effect of the addition is poor. On the other hand, if the content exceeds 0.5 mass%, the graphitization accelerating effect is saturated. Since the hot deformability is remarkably reduced, the content is set in the range of 0.01 to 0.5 mass%. Preferably, the range is 0.02 to 0.05 mass%.

【0012】B:0.0003〜0.0150mass% Bは、窒化物(BN)を形成することにより、セメンタ
イトの安定化を抑制して黒鉛結晶化の核となって黒鉛化
を促進すると同時に、焼入れ性を高めて、強度ならびに
転動疲労寿命を向上させるので積極的に添加する。0.00
03mass%未満では添加効果に乏しく、一方 0.0150mass
%を超えると効果が飽和に達するだけでなく熱間加工性
を低下させるので、0.0003〜0.0150mass%に限定した。
好ましくは0.0005〜0.0025mass%の範囲とする。
B: 0.0003 to 0.0150 mass% B forms nitrides (BN), thereby suppressing the stabilization of cementite, becoming a nucleus of graphite crystallization, promoting graphitization, and simultaneously improving hardenability. It is added positively to increase the strength and the rolling fatigue life. 0.00
If less than 03 mass%, the effect of addition is poor, while 0.0150 mass%
%, The effect not only reaches saturation, but also reduces the hot workability. Therefore, the content is limited to 0.0003 to 0.0150 mass%.
Preferably, it is in the range of 0.0005 to 0.0025 mass%.

【0013】REM :0.0005〜0.0200mass% REM ( 希土類元素) は、酸素と結合し、酸化物として鋼
中に微細分散することによって、黒鉛の核となる窒化物
の微細分散を助成するのみならず、自らも黒鉛結晶化の
核となり、黒鉛化を促進する作用を担う。この作用は0.
0005mass%以上の添加をもって発揮されるが、0.0200ma
ss%を超えて添加してもその作用効果が飽和するだけで
はなく被削性の劣化を招くので、0.0005〜0.0200mass%
に限定した。好ましくは0.0020〜0.015 mass%の範囲と
する。
REM: 0.0005 to 0.0200 mass% REM (rare earth element) combines with oxygen and finely disperses in steel as an oxide, thereby not only assisting the fine dispersion of nitride as a graphite nucleus. Itself also serves as a nucleus for graphite crystallization and promotes graphitization. This effect is 0.
0005mass% or more is exerted, but 0.0200ma
Even if added in excess of ss%, not only the action and effects are saturated, but also the machinability is deteriorated, so 0.0005 to 0.0200 mass%
Limited to. Preferably, it is in the range of 0.0020 to 0.015 mass%.

【0014】Ti:0.005 〜0.05mass% Tiは、TiNを形成することにより、Nによるセメンタイ
トの安定化を抑制し、黒鉛の結晶化の核となって黒鉛化
を促進すると同時に、溶製時の脱酸材として必要なこと
から積極的に添加するが、0.005 mass%未満ではその添
加効果に乏しく、一方0.05mass%を超えて含有させても
その効果は飽和に達するだけでなく、転動疲労寿命の劣
化を招くので、0.005 〜0.05mass%の範囲に限定した。
好ましくは0.01〜0.03mass%とする。
Ti: 0.005 to 0.05 mass% Ti forms TiN, thereby suppressing the stabilization of cementite by N, promoting crystallization as a nucleus of graphite and promoting graphitization. Actively added because it is necessary as a deoxidizing material, its effect is poor when it is less than 0.005 mass%, but its effect is not only saturated when it exceeds 0.05 mass%, but also when rolling fatigue Since the life is deteriorated, the range is limited to the range of 0.005 to 0.05 mass%.
Preferably, it is 0.01 to 0.03 mass%.

【0015】Zr:0.005 〜0.2 mass% Zrは、Nと結合して窒化物を形成することにより、Nに
よる鉄炭化物 (セメンタイト) の安定化を抑制するとと
もに、窒化物が黒鉛の核として作用し、黒鉛化を促進す
る元素であるから積極的に添加する。しかし、その含有
量が0.005 mass%未満では添加の効果に乏しく、一方
0.2mass%を超えてもその添加効果が飽和するだけでな
く、被削性の劣化を招くので、0.005 〜0.2 mass%の範
囲に限定した。好ましくは0.01〜0.2 mass%の範囲とす
る。
Zr: 0.005 to 0.2 mass% Zr combines with N to form a nitride, thereby suppressing the stabilization of iron carbide (cementite) by N and causing the nitride to act as a graphite nucleus. , Since it is an element that promotes graphitization, it is positively added. However, if the content is less than 0.005 mass%, the effect of the addition is poor.
If the content exceeds 0.2 mass%, not only the effect of the addition is saturated, but also the machinability is deteriorated. Therefore, the content is limited to the range of 0.005 to 0.2 mass%. Preferably, it is in the range of 0.01 to 0.2 mass%.

【0016】N:0.0015〜0.0150mass% Nは、B, Al, Tiなどと結合して窒化物を形成すること
により、これを核として黒鉛の結晶化が促進し、かつ結
晶粒を微細化して強度, 靱性を向上させるので積極的に
用いる。こうした効果は、0.0015mass%以上の添加を必
要とするが、0.0150mass%を超えると鉄炭化物 (セメン
タイト) が安定化してかえって黒鉛化を阻害するので、
0.0015〜0.0150mass%の範囲に限定した。好ましくは0.
0020〜0.0050mass%の範囲とする。
N: 0.0015 to 0.0150 mass% N combines with B, Al, Ti, etc. to form a nitride, which promotes the crystallization of graphite using the nitride as a nucleus and refines the crystal grains. Actively used to improve strength and toughness. Such an effect requires the addition of 0.0015 mass% or more, but if it exceeds 0.0150 mass%, iron carbide (cementite) stabilizes and rather inhibits graphitization.
It was limited to the range of 0.0015 to 0.0150 mass%. Preferably 0.
The range is from 0020 to 0.0050 mass%.

【0017】O:0.0020mass%以下 Oは、硬質な酸化物系非金属介在物を形成し、転動疲労
寿命を低下させることから、可能な限り低いことが望ま
しく、0.0020mass%以下とする。
O: 0.0020 mass% or less O is preferably as low as possible, and 0.0020 mass% or less, since it forms hard oxide-based nonmetallic inclusions and reduces the rolling fatigue life.

【0018】次に、本発明においては、焼入れ性を高め
て強度ならびに転動疲労寿命, すなわち転がり寿命を向
上させるという共通した目的の下に、表1に示す理由に
より、さらに下記の量を上限とする強化元素を添加す
る。 Cr≦1.0 mass%、 Mo:≦1.0 mass%、V≦0.5 mass
%、 Nb:≦0.5 mass%、Ni≦3.0 mass%、 Cu:≦3.
0 mass%、Co≦3.0 mass%
Next, in the present invention, for the reasons shown in Table 1, the following amounts are further increased under the common purpose of enhancing the hardenability and improving the strength and rolling fatigue life, that is, the rolling life. Is added. Cr ≦ 1.0 mass%, Mo: ≦ 1.0 mass%, V ≦ 0.5 mass
%, Nb: ≤ 0.5 mass%, Ni ≤ 3.0 mass%, Cu: ≤ 3.
0 mass%, Co ≦ 3.0 mass%

【0019】[0019]

【表1】 [Table 1]

【0020】さらに、本発明においては、被削性を改善
するために適正量のS, Se, Te, Pb, Bi, Ca, Mg, P,
Sn, As, S等を添加しても、本発明で目的とする黒鉛
化, 加工性, ならびに転動疲労寿命を阻害することな
く、容易に被削性を改善することができる。なお、P
は、鋼の靱性ならびに転動疲労寿命を低下させることか
ら、0.025 mass%以下、さらに0.015 mass%以下の範囲
とすることが好ましい。また、Sは、Mnと結合してMnS
を形成し、被削性を向上させる。しかし、多量に含有さ
せると転動疲労寿命を低下させることから、0.025 mass
%以下、好ましくは0.015 mass%以下に抑えるのがよ
い。
Further, in the present invention, an appropriate amount of S, Se, Te, Pb, Bi, Ca, Mg, P,
Even if Sn, As, S, etc. are added, the machinability can be easily improved without impairing the graphitization, workability, and rolling fatigue life, which are the objects of the present invention. Note that P
Is preferably 0.025 mass% or less, and more preferably 0.015 mass% or less, because it reduces the toughness and rolling fatigue life of steel. S is combined with Mn to form MnS
To improve machinability. However, if it is contained in a large amount, the rolling fatigue life is reduced.
% Or less, preferably 0.015 mass% or less.

【0021】また、本発明においては、上述した鋼成分
組成の調整が重要であることは言うまでもないが、さら
に金属組織も重要である。すなわち、本発明の金属組織
は、主として黒鉛とフェライトからなる組織とする必要
がある。ただし、添加C量の約50%未満がセメンタイト
として存在しても、転動疲労寿命の確保、十分な被切削
性あるいは熱間鍛造性を得る上では弊害はない。
In the present invention, it is needless to say that the above-mentioned adjustment of the steel composition is important, but the metal structure is also important. That is, the metal structure of the present invention needs to be a structure mainly composed of graphite and ferrite. However, even if less than about 50% of the added C amount is present as cementite, there is no harm in securing the rolling fatigue life and obtaining sufficient machinability or hot forgeability.

【0022】次に、本発明材料は、表層部の硬化層にお
ける残留オーステナイト量(γ量)を体積比にして10〜
35%にすることが有効である。このような量の残留オー
ステナイトが鋼材表層部組織中に存在すると、初期の繰
り返し応力負荷によりマルテンサイトへ加工誘起変態し
て強度を高めるとともに、非金属介在物の悪影響を緩和
し、転動疲労寿命を向上させる。しかし、あまり多すぎ
る場合(>35%) には硬さを十分満足しきれず、かえっ
て転動疲労寿命を低下させる。従って、本発明において
残留オーステナイト量は10〜35%の範囲、好ましくは15
〜25%の範囲とする。
Next, in the material of the present invention, the amount of retained austenite (γ amount) in the hardened layer of the surface layer portion is 10 to 10% by volume ratio.
It is effective to make it 35%. When such amount of retained austenite is present in the structure of the steel surface layer, work-induced transformation into martensite by the initial cyclic stress load increases the strength, reduces the adverse effects of nonmetallic inclusions, and reduces rolling fatigue life. Improve. However, when the amount is too large (> 35%), the hardness cannot be sufficiently satisfied, and the rolling fatigue life is rather reduced. Therefore, in the present invention, the amount of retained austenite is in the range of 10 to 35%, preferably 15%.
Within the range of ~ 25%.

【0023】[0023]

【実施例】表2〜表10に示す化学組成を有する鋼材を常
法にて溶製し、連続鋳造によりブルームとした後、ビレ
ット圧延を経て52mmφの棒鋼とした。次いで、700 ℃で
10h の等温保持後空冷することからなる黒鉛化処理を施
した。この時、一部の供試材については、785 ℃で5h
の等温保持を行い、650 ℃まで15℃/h で徐冷後に空冷
することからなる炭化物球状化処理を施した。
EXAMPLES Steel materials having the chemical compositions shown in Tables 2 to 10 were melted by a conventional method, turned into a bloom by continuous casting, and then billet-rolled into a 52 mmφ steel bar. Then at 700 ° C
Graphitization treatment was performed, which consisted of air-cooling after 10 hours of isothermal holding. At this time, for some test materials, 5 hours at 785 ° C
, And then gradually cooled to 650 ° C. at 15 ° C./h and then air-cooled to carry out a carbide spheroidizing treatment.

【0024】次に、上記黒鉛化処理あるいは炭化物球状
化処理後、 840 ℃で30min の加熱保持しその後、油焼入れ。 15kHzの高周波焼入れ。 カーボンポテンシャル:0.8 %で930 ℃で4hの加
熱保持し、その後、油焼入れのいずれかの硬化熱処理を
行い、180 ℃×2hの焼もどしを行った。なお、一部の試
験片についてはの加熱温度を高め、残留γ量を強制的
に増加させた。そして、ラッピング仕上によって12mmφ
×22mmの円筒状試験片を得た。この時、試験片試験面粗
度はいずれもRa:0.1 μm以下とした。試練片は、ラジ
アル型転動疲労試験機により、ヘルツ最大接触応力:60
0 kgf/mm2 、繰り返し応力数:約46500cpm、潤滑:#68
タービン飛沫油、の条件で転動疲労寿命試験を行った。
その試験結果は、ワイブル分布に従うものとして確率紙
上にプロットし、B50寿命 (累積破損確率:50%での剥
離発生までの総負荷回数) を求め、鋼材No. 1 をそれぞ
れ1として評価した。
Next, after the above graphitization treatment or carbide spheroidization treatment, the mixture is heated and maintained at 840 ° C. for 30 minutes, and then oil quenched. 15kHz induction hardening. The carbon potential was kept at 930 ° C. for 4 hours at a carbon potential of 0.8%, followed by any one of hardening heat treatments such as oil quenching and tempering at 180 ° C. × 2 hours. The heating temperature of some of the test pieces was increased to forcibly increase the amount of residual γ. And 12mmφ by wrapping finish
A cylindrical test piece of × 22 mm was obtained. At this time, the test surface roughness of each test piece was set to Ra: 0.1 μm or less. The test piece was tested with a radial type rolling fatigue tester to determine the maximum contact stress in Hertz: 60
0 kgf / mm 2 , number of repeated stress: about 46500 cpm, lubrication: # 68
A rolling fatigue life test was performed under conditions of turbine splash oil.
The test results are plotted on a probability paper as Weibull distribution, B 50 life: seeking (cumulative failure probability total load count until flaking occurs at 50%) was assessed steel No. 1 as respectively 1.

【0025】なお、黒鉛化処理あるいは炭化物球状化処
理を行った供試材については、その黒鉛化率ならびに平
均黒鉛粒径を測定した。被削性試験については、高速度
工具鋼SKH4を用い、切り込み:2mm、送り:0.25mm
/rev., および速度:70m/min で実施し、切削不能とな
るまでの時間を工具寿命として評価した。冷間鍛造試験
については、15mmφ×22.5mmH の試験片を切削加工によ
り作成し、端面完全拘束の条件で逐次圧縮を実施し、加
工時の変形抵抗および限界圧縮率を求めた。ここで、限
界圧縮率は試験片に割れが発生を始める圧縮率と定義し
た。評価結果を表2〜10にまとめて示す。
The graphitization rate and the average graphite particle size of the test materials which had been subjected to the graphitization treatment or the carbide spheroidization treatment were measured. For the machinability test, using high-speed tool steel SKH4, depth of cut: 2 mm, feed: 0.25 mm
/ Rev., And speed: 70 m / min, and the time until cutting became impossible was evaluated as tool life. As for the cold forging test, a test piece of 15 mmφ × 22.5 mmH was prepared by cutting, and the compression was sequentially performed under the condition of complete constraint of the end face, and the deformation resistance and the critical compression ratio during the processing were obtained. Here, the critical compression ratio was defined as the compression ratio at which cracks began to occur in the test piece. The evaluation results are shown in Tables 2 to 10.

【0026】 Bベース材(表2の1, 表2の2) C量が本発明範囲よりも低い鋼材No.25 、Si量が低い鋼
材No. 26、B量が低い鋼材No.27 ならびにSi量が低い鋼
材No.28 では、変形抵抗ならびに限界圧縮率にて評価さ
れる冷間鍛造性、工具寿命にて評価される切削性、ある
いは転動疲労寿命のいずれかが、従来の浸漬焼入れ鋼(
鋼材No.1) 、高周波焼入れ鋼( 鋼材No.2) 、あるいは浸
炭焼入れ鋼( 鋼材No.3およびNo.4) のいずれかに劣って
いる。これに対し、本発明鋼である鋼材No.5〜No.24
は、冷間鍛造性、切削性、および転動疲労寿命は、いず
れもどの従来鋼( 鋼材No.1, 鋼材No.2, 鋼材No.3, およ
びNo.4) よりも優れている。なかでも、Cr, Mo, Nb, C
u, Coより選ばれる1種あるいは2種以上を添加した鋼
材No.14 〜No.25 は、鍛造性あるいは切削性を著しく阻
害することなく転動疲労寿命を向上させている。さら
に、No.10 とNo.11 は、同一鋼材により焼入れ温度を代
えて残留γ量を変化させたものであるが、残留γ量が高
い鋼材No.11 の転動疲労寿命は残留γ量が低い鋼材No.1
0 よりも改善されており、軸受部材の寿命向上に有効で
あることがわかる。
B base material (Table 1, 1 and Table 2, 2) Steel No. 25 having a lower C content than that of the present invention, steel No. 26 having a low Si content, steel No. 27 having a low B content, and Si In steel material No. 28, which has a low amount, cold forging property evaluated by deformation resistance and critical compressibility, machinability evaluated by tool life, or rolling fatigue life is the same as conventional immersion hardened steel. (
It is inferior to any of steel No.1), induction hardened steel (steel No.2), or carburized hardened steel (steel No.3 and No.4). On the other hand, steel materials No. 5 to No. 24
All of them have better cold forgeability, machinability and rolling fatigue life than any conventional steel (steel No.1, steel No.2, steel No.3 and No.4). Above all, Cr, Mo, Nb, C
Steel materials No. 14 to No. 25 to which one or more selected from u and Co are added have improved rolling fatigue life without significantly impairing forgeability or machinability. In addition, No. 10 and No. 11 were obtained by changing the residual γ amount by changing the quenching temperature using the same steel material, but the rolling fatigue life of steel material No. 11 with a high residual γ amount was No.1 low steel material
0, which is effective in improving the life of the bearing member.

【0027】 [0027]

【0028】 [0028]

【0029】 Alベース材(表3の1, 表3の2, 表
4の1, 表4の2) CおよびAl量が本発明の範囲よりも低いNo.47 およびN
o.48 鋼は、従来鋼よりも被削性が低下している。ま
た、O量が本発明の範囲よりも高いNo.50 鋼において
は、冷間鍛造性および被削性は従来鋼よりも優れている
にも拘わらず転動疲労寿命が従来鋼よりも低い。No.51
〜No.69 にAl−B複合添加鋼の諸特性を示す。いずれの
鋼も従来鋼に比較して転動疲労寿命, 冷間鍛造性および
被削性は優れている。また、Al単独添加材に比較して黒
鉛化率が高く、その結果、被削性および冷間鍛造性が向
上している。
Al base material (1, 3 in Table 3, 2 in Table 3, 1 in Table 4, 2 in Table 4) No. 47 and N in which the amounts of C and Al are lower than the range of the present invention.
o.48 steel has lower machinability than conventional steel. In addition, in No. 50 steel having an O content higher than the range of the present invention, the rolling fatigue life is lower than that of the conventional steel although the cold forgeability and machinability are superior to the conventional steel. No.51
No. 69 to No. 69 show various characteristics of the Al-B composite added steel. All steels have better rolling fatigue life, cold forgeability and machinability than conventional steels. In addition, the graphitization rate is higher than that of the single additive Al, and as a result, machinability and cold forgeability are improved.

【0030】 [0030]

【0031】 [0031]

【0032】 [0032]

【0033】 [0033]

【0034】 REM ベース材(表5の1, 表5の2,
表6の1, 表6の2) No.88, 89 および90鋼は、C, Si, REM が本発明範囲外
の場合である。これらの鋼はいずれも黒鉛化率が低く、
このために被削性は従来鋼よりも劣っている。また、冷
間鍛造性は従来鋼よりも優れているが、発明例であるN
o.70 〜87鋼に比較すると、とくに変形抵抗が上昇して
いる。また、No.91 鋼は、冷間鍛造性および被削性とも
に優れているがO量が高く、その結果、転動疲労寿命は
従来鋼よりも低い。No.92 〜110 鋼は、REM とB、REM
とAlおよびREM −B−Alの複合添加鋼の場合の特性を示
す。REM 単独添加の場合に比較して黒鉛化率が向上し、
その結果、冷間鍛造性および被削性もREM 単独添加の場
合に比較して向上している。
REM base material (Table 5-1, Table 5 2,
No. 88, 89 and 90 steels in Table 6, 1 and 2 in Table 6 are cases where C, Si and REM are out of the range of the present invention. Each of these steels has a low graphitization rate,
For this reason, the machinability is inferior to the conventional steel. Further, although the cold forgeability is superior to the conventional steel, the N
o. Compared with 70 to 87 steels, especially the deformation resistance is increased. Further, the No. 91 steel is excellent in both cold forgeability and machinability, but has a high O content, and as a result, the rolling fatigue life is lower than that of the conventional steel. No.92-110 steel is REM and B, REM
The following shows the characteristics in the case of a composite steel containing Al and REM-B-Al. Graphitization rate is improved compared to the case of adding REM alone,
As a result, the cold forgeability and machinability are also improved as compared to the case where REM is added alone.

【0035】 [0035]

【0036】 [0036]

【0037】 [0037]

【0038】 [0038]

【0039】 Tiベース材(表7の1, 表7の2, 表
8の1, 表8の2) No.129, 130 および131 鋼は、C, Si, Tiが本発明範囲
外の場合である。これらの鋼はいずれも黒鉛化率が低く
このために被削性は従来鋼よりも劣っている。また、冷
間鍛造性は従来鋼よりも優れているが、発明例であるN
o.111〜128 鋼に比較するととくに変形抵抗が上昇して
いる。また、No.132鋼は冷間鍛造性および被削性ともに
優れているがO量が高く、その結果、転動疲労寿命は従
来鋼よりも低い。No.133〜151 鋼は、TiとB, REM ,Al
の複合添加鋼の場合の特性を示す。REM 単独添加の場合
に比較して黒鉛化率が向上し、その結果、冷間鍛造性お
よび被削性もTi単独添加の場合に比較して向上してい
る。
No. 129, 130 and 131 Ti base materials (Table 7-1, Table 7 2, Table 8 1, Table 8 2) show that C, Si and Ti are out of the range of the present invention. is there. Each of these steels has a low graphitization rate, so that the machinability is inferior to the conventional steel. Further, although the cold forgeability is superior to the conventional steel, the N
o. Compared with 111-128 steel, the deformation resistance is particularly high. Also, No. 132 steel is excellent in both cold forgeability and machinability, but has a high O content, and as a result, the rolling fatigue life is lower than that of the conventional steel. No.133-151 Steels are made of Ti and B, REM, Al
The characteristics in the case of the composite added steel are shown. The graphitization rate is improved as compared with the case of adding REM alone, and as a result, the cold forgeability and machinability are also improved as compared with the case of adding Ti alone.

【0040】 [0040]

【0041】 [0041]

【0042】 [0042]

【0043】 [0043]

【0044】 Zrベース材(表9の1, 表9の2, 表
10の1, 表10の2) No.170, 171 および172 鋼は、C, Si, REM が本発明範
囲外の場合である。これらの鋼はいずれも黒鉛化率が低
く、このために被削性は従来鋼よりも劣っている。ま
た、冷間鍛造性は従来鋼よりも優れているが、発明例で
あるNo.152〜169鋼に比較すると、とくに変形抵抗が上
昇している。また、No.173は、冷間鍛造性および被削性
ともにすぐれているがO量が高く、その結果、転動疲労
寿命は従来鋼よりも低い。No.174〜192 鋼は、ZrとAl,
B, TiおよびREM 複合添加鋼の場合の特性を示す。Zr単
独添加の場合に比較して黒鉛化率が向上し、その結合、
冷間鍛造性および被削性もZr単独添加の場合に比較して
向上している。
Zr base material (Table 9, Table 2, Table 9, Table 2)
10-1 and Table 10-2) No. 170, 171 and 172 steels have C, Si and REM outside the scope of the present invention. Each of these steels has a low graphitization rate, and as a result, its machinability is inferior to conventional steels. Further, although the cold forgeability is superior to that of the conventional steel, the deformation resistance is particularly increased as compared with the inventive examples No. 152 to 169. No. 173 is excellent in both cold forgeability and machinability, but has a high O content, and as a result, the rolling fatigue life is lower than that of conventional steel. No.174 ~ 192 Steels are Zr and Al,
The characteristics in the case of B, Ti and REM composite additive steel are shown. Graphitization rate is improved compared to the case of adding Zr alone,
The cold forgeability and machinability are also improved as compared with the case of adding Zr alone.

【0045】 [0045]

【0046】 [0046]

【0047】 [0047]

【0048】 [0048]

【0049】[0049]

【発明の効果】以上説明したように本発明は、所定の化
学組成を有する鋼材を成形加工前に黒鉛とフェライトを
主体とする組織とし、次いで硬化熱処理を行うことによ
って得られる、加工性に優れた軸受部材であるから、転
がり軸受や歯車といった転動部品において、転動疲労寿
命を損なうことなく成形のための鍛造あるいは切削加工
性を著しく向上することができる。
As described above, the present invention provides an excellent workability obtained by forming a steel material having a predetermined chemical composition into a structure mainly composed of graphite and ferrite before forming and then performing a hardening heat treatment. As a result, the forging or cutting workability for forming can be remarkably improved without impairing the rolling fatigue life of rolling components such as rolling bearings and gears.

フロントページの続き (72)発明者 安本 聡 千葉県千葉市中央区川崎町1番地 川崎 製鉄株式会社技術研究本部内 (72)発明者 松崎 明博 千葉県千葉市中央区川崎町1番地 川崎 製鉄株式会社技術研究本部内 (72)発明者 天野 虔一 千葉県千葉市中央区川崎町1番地 川崎 製鉄株式会社技術研究本部内 (56)参考文献 特開 平1−132739(JP,A) 特開 平4−202744(JP,A) 特開 平5−239588(JP,A) 特開 平6−323399(JP,A) 特開 平6−116679(JP,A) 特開 平2−125841(JP,A) 特開 平3−100142(JP,A)Continuation of front page    (72) Inventor Satoshi Yasumoto               1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba               Steel Research Institute (72) Inventor Akihiro Matsuzaki               1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba               Steel Research Institute (72) Inventor Kenichi Amano               1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba               Steel Research Institute                (56) References JP-A-1-132739 (JP, A)                 JP-A-4-202744 (JP, A)                 JP-A-5-239588 (JP, A)                 JP-A-6-323399 (JP, A)                 JP-A-6-116679 (JP, A)                 Japanese Patent Application Laid-Open No. 2-128441 (JP, A)                 JP-A-3-100142 (JP, A)

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項1】C:0.1 〜1.5 mass%、 Si:0.5 〜2.0 mass%、 Mn:0.1 〜2.5 mass%、 N:0.0015〜0.0150mass%、 O:0.0020mass%以下を含有し、かつ Al:0.01〜0.5 mass%、 B:0.0003〜0.0150mass%、 Ti:0.005 〜0.05mass%、 REM :0.0005〜0.0200mass%、 およびZr:0.005 〜0.2 mass% のうちから選ばれる1種または2種以上を含有し、残部
がFeおよび不可避的不純物からなる成分組成を有すると
共に、フェライトとセメンタイトの50%以上が黒鉛化し
た組織からなるものであって、表層部には残留オーステ
ナイト量が10〜25%で硬度Hvが650以上の硬化熱処理に
よって形成された硬化層を設けてなることを特徴とする
転動部材。
1. C: 0.1 to 1.5 mass%, Si: 0.5 to 2.0 mass%, Mn: 0.1 to 2.5 mass%, N: 0.0015 to 0.0150 mass%, O: 0.0020 mass% or less, and Al: One or more selected from 0.01 to 0.5 mass%, B: 0.0003 to 0.0150 mass%, Ti: 0.005 to 0.05 mass%, REM: 0.0005 to 0.0200 mass%, and Zr: 0.005 to 0.2 mass% Contains, with the balance being Fe and unavoidable impurities, and at least 50% of ferrite and cementite are graphitized.
With a residual austenitic surface layer
For hardening heat treatment with a knight amount of 10-25% and a hardness Hv of 650 or more
A rolling member provided with a cured layer thus formed .
【請求項2】請求項1に記載の転動部材の成分に加え、
さらに、 Cr:1.0 mass%以下、Mo:1.0 mass%以下、 V:0.5 mass%以下、Nb:0.5 mass%以下、 Ni:3.0 mass%以下、Cu:3.0 mass%以下、 Co:3.0 mass%以下 のうちから選ばれるいずれか1種または2種以上の元素
を添加した成分組成にしたことを特徴とする転動部材。
2. In addition to the components of the rolling member according to claim 1,
Cr: 1.0 mass% or less, Mo: 1.0 mass% or less, V: 0.5 mass% or less, Nb: 0.5 mass% or less, Ni: 3.0 mass% or less, Cu: 3.0 mass% or less, Co: 3.0 mass% or less A rolling member characterized in that it has a component composition to which one or two or more elements selected from the above are added.
JP15387994A 1994-07-05 1994-07-05 Rolling member Expired - Fee Related JP3538900B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP15387994A JP3538900B2 (en) 1994-07-05 1994-07-05 Rolling member

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JP4912385B2 (en) * 2003-03-04 2012-04-11 株式会社小松製作所 Manufacturing method of rolling member
JP4390576B2 (en) * 2003-03-04 2009-12-24 株式会社小松製作所 Rolling member
JP4390526B2 (en) * 2003-03-11 2009-12-24 株式会社小松製作所 Rolling member and manufacturing method thereof
JP5368885B2 (en) * 2009-06-05 2013-12-18 株式会社神戸製鋼所 Machine structural steel with excellent hot workability and machinability
CN102985577B (en) * 2010-07-14 2015-05-06 新日铁住金株式会社 Steel having excellent machinability for mechanical structure
JP6205960B2 (en) * 2013-08-05 2017-10-04 新日鐵住金株式会社 Steel for bearing
JP6205961B2 (en) * 2013-08-05 2017-10-04 新日鐵住金株式会社 Bearing, rolling bearing and manufacturing method thereof

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