JPH09302443A - Bearing steel - Google Patents
Bearing steelInfo
- Publication number
- JPH09302443A JPH09302443A JP11890196A JP11890196A JPH09302443A JP H09302443 A JPH09302443 A JP H09302443A JP 11890196 A JP11890196 A JP 11890196A JP 11890196 A JP11890196 A JP 11890196A JP H09302443 A JPH09302443 A JP H09302443A
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- steel
- fatigue life
- cold
- workability
- Prior art date
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- Heat Treatment Of Steel (AREA)
- Rolling Contact Bearings (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ころ軸受、玉軸受
のような転がり軸受の要素部材に用いて好適な軸受用鋼
に関し、とくに冷間加工性のほか、転動疲労寿命特性に
優れる安価な軸受用鋼に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing steel suitable for use as an element member of rolling bearings such as roller bearings and ball bearings, and particularly to cold workability and low rolling fatigue life characteristics. Bearing steel.
【０００２】[0002]
【従来の技術】産業機械および自動車部品等に用いられ
る軸受部品は、ＪＩＳＧ４８０５に規定されているＳＵ
Ｊ２に代表されるＣ：0.95〜1.10wt％とCr：1.30〜1.60
wt％を含む高炭素クロム軸受鋼が最も一般的に用いられ
ている。この高炭素クロム軸受鋼は、溶製後、1250℃程
度で約30時間の高温でかつ長時間の拡散焼なましをへ
て、所定の寸法の棒鋼に圧延される。さらに軸受部品に
仕上げるため、球状化焼なましを施した後、切削加工
や、冷間加工あるいは温間加工等の成形加工を行い、そ
の後、焼入れ、焼もどしが実施される。ここに、拡散焼
なましの目的は、溶製時に発生して転動疲労寿命に悪影
響を及ぼす炭素とクロム等が結合した巨大炭化物の消散
のためである。また、球状化焼なましの目的は、高い炭
素濃度に起因する、圧延ままでの非常に高い硬さを低下
させ、引き続く各種の加工を容易にするためである。さ
らに、焼入れおよび焼もどしは、転がり軸受に必要な硬
さと靱性を確保するために実施するものである。2. Description of the Related Art Bearing parts used in industrial machines and automobile parts are SU specified in JIS G4805.
J2 typified by C: 0.95 to 1.10 wt% and Cr: 1.30 to 1.60
High carbon chromium bearing steels containing wt% are most commonly used. This high carbon chrome bearing steel is melted and then rolled at a high temperature of about 1250 ° C. for about 30 hours at a high temperature for a long period of diffusion annealing to be rolled into a steel bar having a predetermined size. Further, in order to finish the bearing component, spheroidizing annealing is performed, followed by forming processing such as cutting, cold working or warm working, and then quenching and tempering. Here, the purpose of the diffusion annealing is to dissipate the giant carbide formed by combining carbon, chromium, etc., which occurs during melting and has a bad influence on the rolling fatigue life. The purpose of the spheroidizing annealing is to reduce the extremely high hardness in the as-rolled state due to the high carbon concentration, and to facilitate various subsequent processing. Further, quenching and tempering are performed to ensure the hardness and toughness required for the rolling bearing.
【０００３】[0003]
【発明が解決しようとする課題】ところで、近年、切削
加工によって成形加工されていた軸受部品は、鋼材の歩
留り向上を狙って冷間鍛造等のさらに厳しい加工が行わ
れてきている。これら冷間での過酷な成形加工は、歩留
り向上のメリット以外に特にエネルギ−原単位削減、作
業環境向上および寸法精度向上等の点から増加の傾向に
ある。この冷間鍛造等の厳しい加工を行う場合に、従来
の高炭素クロム軸受鋼を使用すると、冷間鍛造時に割れ
が発生するために冷間加工に制限が生ずるなど加工性に
問題があった。また、成分に起因する巨大炭化物の消散
のため、高温でかつ長時間の拡散焼なましが不可欠であ
り大幅なコストアップ要因となっている。By the way, in recent years, bearing parts which have been formed by cutting have been subjected to more severe working such as cold forging in order to improve the yield of steel products. In addition to the merit of improving the yield, these severe cold forming processes tend to increase particularly in terms of energy consumption reduction, working environment improvement, and dimensional accuracy improvement. When a conventional high carbon chrome bearing steel is used when performing severe working such as cold forging, cracking occurs during cold forging, which causes a problem in workability such as restriction in cold working. In addition, diffusion annealing of high temperature and long time is indispensable because of the dissipation of huge carbides caused by the components, which is a major factor of cost increase.
【０００４】これらの問題を解決する方法として、たと
えば特開平２−５４７３９号公報の技術が開示されてい
る。この方法は、素材の炭素量を低減させたことにより
切削抵抗あるいは変形抵抗を低くしているので、高炭素
クロム鋼と比較して概して冷間加工性はある程度向上し
たものの、成分範囲によっては、依然として従来の高炭
素クロム鋼の冷間鍛造可能範囲であっても割れが発生し
ている。さらに、高温でかつ長時間の拡散焼なましの省
略についてはまったく考慮されていない。また、特開平
１−１２７６５１号公報に開示の方法では、上記の問題
点である拡散焼なまし省略は可能であるものの、加工性
の問題は依然として残されたままである。そこで、本発
明の目的は、転動疲労寿命などの機械特性を損ねること
なく、冷間加工性に優れ、拡散焼なましを必要としな
い、安価な軸受用鋼を提供することにある。As a method for solving these problems, for example, the technique disclosed in Japanese Patent Laid-Open No. 2-54739 is disclosed. This method reduces cutting resistance or deformation resistance by reducing the carbon content of the material, so cold workability is generally improved to some extent compared to high carbon chrome steel, but depending on the composition range, Cracking still occurs even within the range of conventional cold forging of high carbon chromium steel. Further, no consideration is given to omitting diffusion annealing at high temperature for a long time. Further, in the method disclosed in Japanese Patent Application Laid-Open No. 1-127651, although the above-mentioned problem of diffusion annealing can be omitted, the problem of workability still remains. Therefore, an object of the present invention is to provide an inexpensive steel for bearings that does not impair mechanical properties such as rolling fatigue life, has excellent cold workability, and does not require diffusion annealing.
【０００５】[0005]
【課題を解決するための手段】本発明者らは、上記の問
題を解決するために鋭意検討を行った結果、冷間鍛造等
の厳しい加工における加工性の向上には、球状化焼なま
し組織が大きく影響を及ぼしていることを見出し、球状
化焼なまし組織を向上させることにより冷間鍛造等の加
工性を向上できることがわかった。さらに研究を重ねた
ところ成分を特定の範囲にすることにより、冷間鍛造等
の加工性が向上し、かつ高温で長時間の拡散焼なましが
省略でき、また転動疲労寿命が従来の高炭素クロム軸受
鋼と比較して同程度以上の冷間加工性に優れた安価な軸
受用鋼を開発したのである。すなわち本発明の要旨構成
は以下のとおりである。Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that spheroidizing annealing is required to improve workability in severe working such as cold forging. It was found that the structure has a great influence, and it was found that the workability such as cold forging can be improved by improving the spheroidized annealing structure. Further studies have shown that by setting the composition of the components within a specific range, the workability such as cold forging can be improved, and long-term diffusion annealing at high temperature can be omitted. We have developed an inexpensive steel for bearings, which has cold workability equivalent to or better than that of carbon chrome bearing steel. That is, the gist of the present invention is as follows.
【０００６】（１）Ｃ：0.70wt％以上、0.80wt％未満、
Si：0.50wt％以上、1.0 wt％以下、Mn：0.10wt％以上、
2.0 wt％以下、Cr：0.40wt％以上、0.95wt％以下、Al：
0.050 wt％以下、 Ｏ：0.0030wt％以下を含有し、残部
はFe及び不可避的不純物からなることを特徴とする冷間
加工性に優れる軸受用鋼。(1) C: 0.70 wt% or more and less than 0.80 wt%,
Si: 0.50 wt% or more, 1.0 wt% or less, Mn: 0.10 wt% or more,
2.0 wt% or less, Cr: 0.40 wt% or more, 0.95 wt% or less, Al:
Bearing steel with excellent cold workability, characterized by containing 0.050 wt% or less, O: 0.0030 wt% or less, and the balance being Fe and inevitable impurities.
【０００７】（２）Ｃ：0.70wt％以上、0.80wt％未満、
Si：0.50wt％以上、1.0 wt％以下、Mn：0.10wt％以上、
2.0 wt％以下、Cr：0.40wt％以上、0.95wt％以下、Al：
0.050 wt％以下、 Ｏ：0.0030wt％以下を含み、かつN
i：0.10wt％以上、1.00wt％以下、Cu：0.05wt％以上、
0.50wt％以下、Mo：0.10wt％以上、1.00wt％以下のうち
から選ばれる１種または２種以上を含有し、残部はFe及
び不可避的不純物からなることを特徴とする冷間加工性
に優れる軸受用鋼。(2) C: 0.70 wt% or more and less than 0.80 wt%,
Si: 0.50 wt% or more, 1.0 wt% or less, Mn: 0.10 wt% or more,
2.0 wt% or less, Cr: 0.40 wt% or more, 0.95 wt% or less, Al:
0.050 wt% or less, O: 0.0030 wt% or less, and N
i: 0.10 wt% or more, 1.00 wt% or less, Cu: 0.05 wt% or more,
0.50 wt% or less, Mo: 0.10 wt% or more, 1.00 wt% or less containing one or more selected, the balance is Fe and inevitable impurities characterized by cold workability Excellent bearing steel.
【０００８】（３）Ｃ：0.70wt％以上、0.80wt％未満、
Si：0.50wt％以上、1.0 wt％以下、Mn：0.10wt％以上、
2.0 wt％以下、Cr：0.40wt％以上、0.95wt％以下、Al：
0.050 wt％以下、 Ｏ：0.0030wt％以下を含み、かつN
b：0.05wt％以上、0.50wt％以下、Ｖ：0.05wt％以上、
0.50wt％以下、Ｗ：0.05wt％以上、0.50wt％以下のうち
から選ばれる１種または２種以上を含有し、残部はFe及
び不可避的不純物からなることを特徴とする冷間加工性
に優れる軸受用鋼。(3) C: 0.70 wt% or more and less than 0.80 wt%,
Si: 0.50 wt% or more, 1.0 wt% or less, Mn: 0.10 wt% or more,
2.0 wt% or less, Cr: 0.40 wt% or more, 0.95 wt% or less, Al:
0.050 wt% or less, O: 0.0030 wt% or less, and N
b: 0.05 wt% or more, 0.50 wt% or less, V: 0.05 wt% or more,
0.50 wt% or less, W: 0.05 wt% or more, 0.50 wt% or less, containing 1 or 2 or more selected, the balance is Fe and unavoidable impurities, cold workability characterized by Excellent bearing steel.
【０００９】（４）Ｃ：0.70wt％以上、0.80wt％未満、
Si：0.50wt％以上、1.0 wt％以下、Mn：0.10wt％以上、
2.0 wt％以下、Cr：0.40wt％以上、0.95wt％以下、Al：
0.050 wt％以下、Ｏ：0.0030wt％以下を含み、かつNi：
0.10wt％以上、1.00wt％以下、Cu：0.05wt％以上、0.50
wt％以下、Mo：0.10wt％以上、1.00wt％以下のうちから
選ばれる１種または２種以上を含有し、さらにNb：0.05
wt％以上、0.50wt％以下、Ｖ：0.05wt％以上、0.50wt％
以下、Ｗ：0.05wt％以上、0.50wt％以下のうちから選ば
れる１種または２種以上を含有し、残部はFe及び不可避
的不純物からなることを特徴とする冷間加工性に優れる
軸受用鋼。(4) C: 0.70 wt% or more and less than 0.80 wt%,
Si: 0.50 wt% or more, 1.0 wt% or less, Mn: 0.10 wt% or more,
2.0 wt% or less, Cr: 0.40 wt% or more, 0.95 wt% or less, Al:
0.050 wt% or less, O: 0.0030 wt% or less, and Ni:
0.10wt% or more, 1.00wt% or less, Cu: 0.05wt% or more, 0.50
wt% or less, Mo: 0.10 wt% or more, 1.00 wt% or less, and contains one or more selected, further Nb: 0.05
wt% or more, 0.50 wt% or less, V: 0.05 wt% or more, 0.50 wt%
Hereinafter, for bearings having excellent cold workability, characterized by containing one or two or more selected from W: 0.05 wt% or more and 0.50 wt% or less, and the balance being Fe and inevitable impurities. steel.
【００１０】[0010]
【発明の実施の形態】本発明にかかる軸受用鋼につい
て、以下に、詳細に説明する。発明者らは、軸受用鋼の
冷間鍛造等の加工性の改善を目指して、冷間鍛造性に及
ぼす球状化焼なまし組織の影響を調べた。図１は、上記
実験から、冷間鍛造時の限界圧縮率と炭化物の球状化率
との関係を示したものである。図１より、球状化率が向
上するほど冷間鍛造性が向上することがわかった。ここ
に、球状化率は、単位面積中に存在する炭化物の中で縦
と横の比（アスペクト比）が２以下の炭化物の個数の全
個数に占める割合（％）で定義している。従って球状化
率を向上させることにより、冷間加工性に優れた軸受鋼
が得られることを知見した。BEST MODE FOR CARRYING OUT THE INVENTION The bearing steel according to the present invention will be described in detail below. The inventors investigated the influence of the spheroidized annealing structure on the cold forgeability in order to improve the workability of the bearing steel such as cold forging. FIG. 1 shows the relationship between the critical compression rate during cold forging and the spheroidization rate of carbides from the above experiment. From FIG. 1, it was found that the cold forgeability was improved as the spheroidization rate was improved. Here, the spheroidization rate is defined as the ratio (%) of the total number of carbides having a vertical to horizontal ratio (aspect ratio) of 2 or less among the carbides present in a unit area. Therefore, it was found that a bearing steel having excellent cold workability can be obtained by improving the spheroidization rate.
【００１１】このように、球状化率向上のためには、球
状化焼なまし条件を適切に制御する必要がある。図２
に、一般的な球状化焼なましのヒ−トパタ−ンの模式図
を示す。発明者は、球状化焼なまし条件に関しても鋭意
調査研究を重ね、球状化率向上には球状化焼なましの最
高加熱温度保持前の炭化物中に含まれるクロム量が球状
化に大きく影響していることを見出した。すなわち、炭
化物中に含まれるクロム量が多いほど、その後の冷却中
に成長する炭化物の核が多く残留し、球状化程度は向上
することが明らかとなった。この理由は、最高加熱温度
において炭化物中に含まれるクロム量が多いほど炭化物
が溶解しにくく、特に小さな炭化物の核が残留しやす
く、これらの核がその後の冷却中に成長して球状化する
ためであると思われる。以上の検討結果から炭化物の球
状化率向上には球状化焼なまし条件に関して、構成主元
素である炭素とクロムを特定範囲に規定する必要がある
ことがわかったのである。これらの成分を含め、各成分
の限定理由について以下に説明する。As described above, in order to improve the spheroidizing rate, it is necessary to appropriately control the spheroidizing annealing conditions. FIG.
Fig. 1 shows a schematic diagram of a general spheroidized annealing heat pattern. The inventor has conducted extensive research and studies on spheroidizing annealing conditions, and in order to improve the spheroidizing rate, the amount of chromium contained in the carbide before holding the maximum heating temperature of the spheroidizing annealing greatly affects the spheroidizing. I found that. That is, it has been clarified that the greater the amount of chromium contained in the carbide, the more the carbide nuclei that grow during the subsequent cooling remain, and the degree of spheroidization is improved. The reason for this is that as the amount of chromium contained in the carbide increases at the maximum heating temperature, the carbide is more difficult to dissolve, and particularly small nuclei of carbide tend to remain, and these nuclei grow and spheroidize during subsequent cooling. Seems to be. From the above examination results, it has been found that in order to improve the spheroidization rate of carbides, it is necessary to regulate the main constituent elements, carbon and chromium, in a specific range regarding the spheroidization annealing conditions. The reasons for limiting each component including these components will be described below.
【００１２】Ｃ：0.70wt％以上、0.80wt％未満 Ｃは、本発明における重要な元素であり、冷間加工性向
上、球状化率の向上に有効な元素であるクロム量との割
合から、また基地に固溶してマルテンサイトを強化し、
強度、耐磨耗性および転動疲労寿命を向上させるうえか
ら、少なくとも0.70wt％以上添加する必要がある。一
方、0.80wt％以上添加すると冷間加工性、温間加工性、
被削性および靱性が低下し、かつ他元素との関係から拡
散焼なまし省略が不可能となる。よって、Ｃ量は0.70〜
0.80wt％未満の範囲とする。C: 0.70 wt% or more and less than 0.80 wt% C is an important element in the present invention, and from the ratio with the amount of chromium, which is an element effective in improving cold workability and spheroidization rate, In addition, solid solution in the base to strengthen martensite,
In order to improve strength, abrasion resistance and rolling contact fatigue life, it is necessary to add at least 0.70 wt% or more. On the other hand, if 0.80 wt% or more is added, cold workability, warm workability,
Machinability and toughness are reduced, and it becomes impossible to omit diffusion annealing due to the relationship with other elements. Therefore, the C content is 0.70-
The range is less than 0.80 wt%.
【００１３】Si：0.50wt％以上、1.0 wt％以下 Siは、脱酸の他に、基地に固溶して転動疲労寿命を向上
させる元素として必要な元素である。含有量が0.50wt％
未満ではこの効果が小さく、一方、1.0 wt％超えて添加
すると、特に球状化後の硬さが上昇するため、被削性お
よび加工性が著しく低下する。よって、Si量は0.50〜1.
0 wt％の範囲に限定する。Si: 0.50 wt% or more and 1.0 wt% or less Si is an element necessary as an element that improves the rolling contact fatigue life by forming a solid solution in the matrix in addition to deoxidizing. Content is 0.50wt%
If it is less than 1.0%, this effect is small. On the other hand, if it is added in an amount of more than 1.0% by weight, the hardness after spheroidizing is particularly increased, so that the machinability and the workability are remarkably reduced. Therefore, the amount of Si is 0.50 to 1.
Limit to the range of 0 wt%.
【００１４】Mn：0.10wt％以上、2.0 wt％以下 Mnは、鋼の焼入性を向上させることによって基地マルテ
ンサイトの靱性を高め、また転動疲労寿命の向上に有効
に寄与する。しかし、0.10wt％に満たないとこの添加効
果に乏しく、一方2.0 wt％を超えて添加すると被削性、
靱性および加工性が著しく低下するので、Mn量は0.10〜
2.0 wt％の範囲に限定する。なお、好ましくは0.50〜1.
20wt％の範囲とするのがよい。Mn: 0.10 wt% or more and 2.0 wt% or less Mn enhances the hardenability of steel to increase the toughness of the base martensite and effectively contributes to the improvement of rolling contact fatigue life. However, if it is less than 0.10 wt%, this addition effect is poor, while if it is added over 2.0 wt%, machinability,
Since the toughness and workability are significantly reduced, the Mn content is 0.10-
Limit to the range of 2.0 wt%. Incidentally, it is preferably 0.50 to 1.
It is preferable to set it in the range of 20 wt%.
【００１５】Cr：0.40wt％以上、0.95wt％以下 Crは、本発明において特に重要な元素である。鋼の焼入
性を高め、基地の強度および靱性を向上させるだけでな
く、冷間加工性向上に密接に関係がある球状化率向上に
有効な元素である。含有量が0.40wt％未満ではこれらの
効果が小さく、一方0.95wt％を超えると他元素との関係
より拡散焼なまし省略が不可能となる。なお、Crのこの
ような効果は、0.80wt％でほぼ飽和し、0.80wt％以上で
は他元素とくにＣ量およびSi量との関係により、溶製時
に巨大炭化物が生成しやすくなる。したがて、Cr添加量
は0.40〜0.95wt％の範囲、好ましくは0.40〜0.80wt％の
範囲とする。Cr: 0.40 wt% or more and 0.95 wt% or less Cr is a particularly important element in the present invention. It is an element effective not only for improving the hardenability of steel and improving the strength and toughness of the matrix, but also for improving the spheroidization rate, which is closely related to the improvement of cold workability. If the content is less than 0.40 wt%, these effects are small. On the other hand, if the content exceeds 0.95 wt%, the diffusion annealing cannot be omitted due to the relationship with other elements. It should be noted that such an effect of Cr is almost saturated at 0.80 wt%, and at 0.80 wt% or more, due to the relationship with other elements, particularly the amount of C and the amount of Si, giant carbides are likely to be formed during melting. Therefore, the Cr addition amount is in the range of 0.40 to 0.95 wt%, preferably in the range of 0.40 to 0.80 wt%.
【００１６】Al：0.050 wt％以下 Alは、脱酸剤として添加するが、Ｏと結合し硬質な酸化
物系介在物を形成するため、転動疲労寿命を低下させ
る。したがって、できる限り低い方が望ましく、0.050
wt％を上限とする。Al: 0.050 wt% or less Al is added as a deoxidizing agent, but since it combines with O to form a hard oxide inclusion, the rolling fatigue life is shortened. Therefore, the lowest possible value is desirable, 0.050
The upper limit is wt%.
【００１７】Ｏ：0.0030wt％以下 Ｏは、Alと結合し、硬質な酸化物系非金属介在物を形成
するため、転動疲労寿命を低下させる。したがって、で
きるかぎり少ない方が望ましく、0.0030wt％を上限とす
る。O: 0.0030 wt% or less O combines with Al to form a hard oxide-based non-metallic inclusion, so that the rolling fatigue life is shortened. Therefore, it is desirable that the amount is as small as possible, and the upper limit is 0.0030 wt%.
【００１８】以上、基本成分について説明したが、本発
明ではさらにMo、Ni、Cuのうちから選んだ１種または２
種以上、および／またはNb、Ｖ、Ｗのうちから選んだ１
種または２種以上を添加することができる。上記各元素
の好適添加量範囲と限定理由は次のとおりである。Ni：
0.10wt％以上、1.00wt％以下、Cu：0.05wt％以上、0.50
wt％以下、Mo：0.10wt％以上、1.00wt％以下 Mo、NiおよびCuは、いずれも、焼入性を高め、鋼の転動
疲労寿命を向上させる有用元素である。しかし、Mo、Cu
が多すぎる場合には、鋼の被削性を低下させ、またNiが
多すぎる場合には残留オ−ステナイトが多量に生成して
鋼材硬さを低下させ転動疲労寿命を低下させるだけでな
く、鋼の被削性をも低下させる。そこで、これらの元素
もかかるおそれのない上記の各範囲で添加するものとし
た。The basic components have been described above, but in the present invention, one or two selected from Mo, Ni and Cu are further used.
1 or more selected from the above and / or Nb, V, W
Seeds or two or more can be added. The preferable addition amount range of each element and the reason for limitation are as follows. Ni:
0.10wt% or more, 1.00wt% or less, Cu: 0.05wt% or more, 0.50
wt% or less, Mo: 0.10 wt% or more, 1.00 wt% or less Mo, Ni and Cu are all useful elements that enhance hardenability and improve rolling fatigue life of steel. However, Mo, Cu
If the amount of Ni is too large, the machinability of the steel is deteriorated, and if the amount of Ni is too large, not only the retained austenite is formed in a large amount to decrease the hardness of the steel material but also to reduce the rolling fatigue life. It also reduces the machinability of steel. Therefore, these elements are also added within the above-mentioned ranges in which there is no fear of this being involved.
【００１９】Nb：0.05wt％以上、0.50wt％以下、Ｖ：0.
05wt％以上、0.50wt％以下、Ｗ：0.05wt％以上、0.50wt
％以下 Nb、ＶおよびＷは、いずれも、鋼中のＣと結合し、耐磨
耗性を向上させるとともに結晶粒の微細化により転動疲
労寿命および靱性の向上に有効に寄与する。しかし、い
ずれの元素も、多すぎる場合には、炭化物が高温で安定
化し、鋼材硬さを低下させ、転動疲労寿命を低下させる
だけでなく、鋼の被削性をも低下させる。そこで、これ
らの元素もかかるおそれのない上記の各範囲で添加する
ものとした。Nb: 0.05 wt% or more, 0.50 wt% or less, V: 0.
05wt% or more, 0.50wt% or less, W: 0.05wt% or more, 0.50wt
% Or less Nb, V and W all combine with C in the steel to improve the wear resistance and effectively contribute to the improvement of rolling fatigue life and toughness due to the refinement of crystal grains. However, if any of the elements is too large, not only the carbide stabilizes at a high temperature, the hardness of the steel material decreases, the rolling fatigue life decreases, but also the machinability of the steel decreases. Therefore, these elements are also added within the above-mentioned ranges in which there is no fear of this being involved.
【００２０】次に、本発明鋼の製造方法について説明す
る。本発明鋼は、転炉、電気炉等いずれの方法で溶製し
てもよく、またスラブの製造は連鋳、造塊いずれの工程
によってもよい。さらに熱間圧延条件および球状化焼な
まし条件も特に限定されることなく、常法に従って行え
ばよい。Next, a method for producing the steel of the present invention will be described. The steel of the present invention may be melted by any method such as a converter or an electric furnace, and the slab may be manufactured by either continuous casting or ingot manufacturing. Further, the hot rolling condition and the spheroidizing annealing condition are not particularly limited, and may be performed according to a conventional method.
【００２１】[0021]
【実施例】以下本発明を実施例にもとづいて説明する。
表１に示す鋼材を転炉により溶製し、連続鋳造法で鋼片
としたのち、65mmφの棒鋼に圧延した。なお、鋼材No.2
1 については、同様に連続鋳造法で鋼片としたのち、さ
らに1250℃で30時間の拡散焼なましを行い、巨大炭化物
の消失後、65mmφの棒鋼に圧延した。次いで、これらの
棒鋼の直径／４の部分より、18mmφの試験片を切り出
し、大気雰囲気で以下の球状化焼なましを行い、冷間鍛
造性を評価した。さらに球状化焼なまし後に焼入れ、焼
もどしを行い、転動疲労寿命を評価するためのサンプル
を採取した。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
The steel materials shown in Table 1 were melted in a converter, made into a steel piece by a continuous casting method, and then rolled into a steel bar having a diameter of 65 mm. Steel material No. 2
Regarding No. 1, steel pieces were similarly made by continuous casting method, further subjected to diffusion annealing at 1250 ° C. for 30 hours, after disappearance of huge carbides, rolled into steel bars of 65 mmφ. Next, 18 mmφ test pieces were cut out from the diameter / 4 portions of these steel bars, and the following spheroidizing annealing was performed in the air atmosphere to evaluate the cold forgeability. Further, after spheroidizing annealing, quenching and tempering were performed, and samples for evaluating rolling fatigue life were taken.
【００２２】球状化焼なましおよび焼入れ、焼もどしの
それぞれの熱処理条件は次のとおりである。 ・球状化焼なまし：750 ℃×２時間→650 ℃まで炉冷、
その後、空冷 ・焼入れ、焼もどし：850 ℃×１時間／水冷、180 ℃×
１時間／空冷 また、冷間鍛造性および転動疲労寿命の試験方法は次の
とおりである。 ・冷間鍛造試験：球状化焼なまし後のサンプルより15mm
φ×20mmの試験片を切り出し、完全拘束の状態で圧縮率
50〜70％における割れ発生率を測定 ・転動疲労寿命：円筒型転動疲労寿命試験機により、ヘ
ルツ最大接触応力：600kgf/mm2、繰り返し応力数：約46
500cpmの条件で試験を行い、試験結果をワイブル分布に
従うものとして確率紙上にまとめ、鋼材No.21 のB10 寿
命（累積破損確率：10％における剥離発生までの総負荷
回数）を１として相対評価 これらの冷間鍛造性および転動疲労寿命の測定結果を表
２に示す。The heat treatment conditions for spheroidizing annealing, quenching, and tempering are as follows.・ Spheroidizing annealing: 750 ℃ × 2 hours → furnace cooling to 650 ℃,
After that, air cooling, quenching, tempering: 850 ℃ × 1 hour / water cooling, 180 ℃ ×
1 hour / air cooling Further, the test methods for cold forgeability and rolling contact fatigue life are as follows.・ Cold forging test: 15mm from spheroidized sample
A φ × 20 mm test piece is cut out, and the compression ratio
Measures crack occurrence rate at 50-70% ・ Rolling fatigue life: Hertz maximum contact stress: 600kgf / mm 2 , cyclic stress number: Approx. 46 by cylindrical rolling fatigue life tester
The test was conducted under the condition of 500 cpm, and the test results were summarized on the probability paper as the ones according to the Weibull distribution, and the relative evaluation was made with the B 10 life of steel material No. 21 (cumulative damage probability: total load count until peeling at 10%) as 1. Table 2 shows the measurement results of these cold forgeability and rolling fatigue life.
【００２３】[0023]
【表１】 [Table 1]
【００２４】[0024]
【表２】 [Table 2]
【００２５】表２より明らかなように、Ｃ含有量が本発
明範囲より低い鋼材No.22,23は冷間加工性の点ではやや
改善されているものの、転動疲労寿命はNo.21 従来材の
0.7倍と0.8 倍に過ぎなかった。Cr含有量が本発明範囲
より低い鋼材No.24,25は、球状化焼なまし後の球状化率
が低く比較的低い圧縮率で割れが発生しており冷間加工
性が低いことがわかる。Si含有量が本発明範囲より低い
鋼材No.26,27は冷間加工性の点では改善されているもの
の、転動疲労寿命はともにNo.21 従来材の0.8倍と0.9
倍にすぎなかった。Ｃ含有量が本発明範囲より高い鋼材
No.28,29およびCr含有量が本発明範囲より高い鋼材No.3
0 は、転動疲労寿命がNo.21 従来材のそれぞれ0.7 倍、
0.6 倍および0.5 倍にすぎなかった。これらは転動疲労
寿命試験片のミクロ組織観察結果より溶製時に生成した
巨大炭化物のために寿命が低いものと推察された。As is clear from Table 2, steel materials Nos. 22 and 23 having a C content lower than the range of the present invention are slightly improved in cold workability, but have a rolling fatigue life of No. 21 conventional. Material
It was only 0.7 and 0.8 times. It can be seen that the steel materials No. 24 and 25 having a Cr content lower than the range of the present invention have low spheroidization rate after spheroidizing annealing and cracking occurs at a relatively low compression rate, and cold workability is low. . Steel Nos. 26 and 27 having Si contents lower than the range of the present invention are improved in cold workability, but rolling fatigue life is 0.8 times and 0.9 times that of No. 21 conventional material.
It was only twice. Steel with C content higher than the range of the present invention
Steel No. 3 with No. 28, 29 and Cr content higher than the range of the present invention
0 means that the rolling fatigue life is 0.7 times that of the No. 21 conventional material,
Only 0.6 times and 0.5 times. From the microstructure observation result of the rolling fatigue life test piece, it was assumed that the life was short because of the huge carbide formed during melting.
【００２６】これらの比較例に対し、鋼材No.1〜No.20
の発明例はいずれも、圧縮率60％まで割れが発生せず、
従来材に比較して格段に優れている。さらに、転動疲労
寿命も従来材の1.3 〜3.1 倍に改善している。また、上
記実施例に示したように、（Ni、Cu、Mo）および／また
は（Nb、Ｖ、Ｗ）の１種または２種以上の添加は、冷間
加工性を損なうことなく転動疲労寿命を向上させている
ことから、その使用目的に応じて、自由な組合わせ添加
が可能なことがわかる。In comparison with these comparative examples, steel materials No. 1 to No. 20
In each of the invention examples, no cracks were generated up to a compression rate of 60%,
Remarkably superior to conventional materials. In addition, the rolling fatigue life is 1.3 to 3.1 times that of the conventional material. Further, as shown in the above examples, addition of one or more of (Ni, Cu, Mo) and / or (Nb, V, W) does not impair cold workability and causes rolling fatigue. From the fact that the life is improved, it is understood that the combination can be freely added depending on the purpose of use.
【００２７】[0027]
【発明の効果】以上示したように、本発明によれば、転
動疲労寿命を阻害することなしに冷間加工性を効果的に
向上することができるので、従来、冷間鍛造時に割れが
発生していた範囲まで加工が可能になる。このため、本
発明によれば、切削加工の省略または簡略化が可能とな
り、材料の歩留り向上および生産性向上を図ることがで
きる。また、本発明によれば、Ｃ、Crの低減により、合
金コストが低減されるだけでなく、従来、鋳造時に生成
する巨大炭化物の消散のために施されていた拡散焼なま
しを省略することが可能となったので、軸受用素材のコ
ストを大幅に低減できる。As described above, according to the present invention, the cold workability can be effectively improved without impairing the rolling fatigue life. It is possible to process up to the range that has occurred. Therefore, according to the present invention, the cutting process can be omitted or simplified, and the material yield and productivity can be improved. Further, according to the present invention, not only the alloy cost is reduced by reducing C and Cr, but also the diffusion annealing conventionally performed for dissipating the giant carbide generated during casting is omitted. Since it is possible, the cost of the bearing material can be significantly reduced.
【図１】炭化物の球状化率と限界圧縮率との関係を示す
図である。FIG. 1 is a diagram showing a relationship between a spheroidization rate of a carbide and a critical compression rate.
【図２】球状化焼きなまし熱処理の温度パターンを示す
模式図である。FIG. 2 is a schematic diagram showing a temperature pattern of spheroidizing annealing heat treatment.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 星野 俊幸 岡山県倉敷市水島川崎通１丁目（番地な し） 川崎製鉄株式会社水島製鉄所内 (72)発明者 天野 虔一 岡山県倉敷市水島川崎通１丁目（番地な し） 川崎製鉄株式会社水島製鉄所内 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiyuki Hoshino 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. 1-chome (without address) Inside Kawasaki Steel Corporation Mizushima Works
Claims (4)
特徴とする冷間加工性に優れる軸受用鋼。1. C: 0.70 wt% or more and less than 0.80 wt%, Si: 0.50 wt% or more, 1.0 wt% or less, Mn: 0.10 wt% or more, 2.0 wt% or less, Cr: 0.40 wt% or more, 0.95 wt %, Al: 0.050 wt% or less, O: 0.0030 wt% or less, and the balance being Fe and inevitable impurities, which is a steel for bearings excellent in cold workability.
はFe及び不可避的不純物からなることを特徴とする冷間
加工性に優れる軸受用鋼。2. C: 0.70 wt% or more and less than 0.80 wt%, Si: 0.50 wt% or more, 1.0 wt% or less, Mn: 0.10 wt% or more, 2.0 wt% or less, Cr: 0.40 wt% or more, 0.95 wt % Or less, Al: 0.050 wt% or less, O: 0.0030 wt% or less, and Ni: 0.10 wt% or more, 1.00 wt% or less, Cu: 0.05 wt% or more, 0.50 wt% or less, Mo: 0.10 wt% or more A steel for bearings having excellent cold workability, characterized by containing one or more selected from 1.00 wt% or less, and the balance being Fe and inevitable impurities.
はFe及び不可避的不純物からなることを特徴とする冷間
加工性に優れる軸受用鋼。3. C: 0.70 wt% or more and less than 0.80 wt%, Si: 0.50 wt% or more, 1.0 wt% or less, Mn: 0.10 wt% or more, 2.0 wt% or less, Cr: 0.40 wt% or more, 0.95 wt. % Or less, Al: 0.050 wt% or less, O: 0.0030 wt% or less, and Nb: 0.05 wt% or more, 0.50 wt% or less, V: 0.05 wt% or more, 0.50 wt% or less, W: 0.05 wt% or more A steel for bearings having excellent cold workability, characterized in that it contains one or more selected from 0.50 wt% or less, and the balance is Fe and inevitable impurities.
に Nb：0.05wt％以上、0.50wt％以下、 Ｖ：0.05wt％以上、0.50wt％以下、 Ｗ：0.05wt％以上、0.50wt％以下 のうちから選ばれる１種または２種以上を含有し、残部
はFe及び不可避的不純物からなることを特徴とする冷間
加工性に優れる軸受用鋼。4. C: 0.70 wt% or more and less than 0.80 wt%, Si: 0.50 wt% or more, 1.0 wt% or less, Mn: 0.10 wt% or more, 2.0 wt% or less, Cr: 0.40 wt% or more, 0.95 wt % Or less, Al: 0.050 wt% or less, O: 0.0030 wt% or less, and Ni: 0.10 wt% or more, 1.00 wt% or less, Cu: 0.05 wt% or more, 0.50 wt% or less, Mo: 0.10 wt% or more , Nb: 0.05 wt% or more, 0.50 wt% or less, V: 0.05 wt% or more, 0.50 wt% or less, W: 0.05 wt% As described above, a bearing steel having excellent cold workability, characterized by containing one or more selected from 0.50 wt% or less, and the balance being Fe and inevitable impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11890196A JP3374006B2 (en) | 1996-05-14 | 1996-05-14 | Bearing steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11890196A JP3374006B2 (en) | 1996-05-14 | 1996-05-14 | Bearing steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09302443A true JPH09302443A (en) | 1997-11-25 |
| JP3374006B2 JP3374006B2 (en) | 2003-02-04 |
Family
ID=14747980
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11890196A Expired - Lifetime JP3374006B2 (en) | 1996-05-14 | 1996-05-14 | Bearing steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3374006B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2781813A1 (en) * | 1998-07-30 | 2000-02-04 | Ascometal Sa | STEEL FOR MAKING A WORKPIECE FOR BEARING |
-
1996
- 1996-05-14 JP JP11890196A patent/JP3374006B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2781813A1 (en) * | 1998-07-30 | 2000-02-04 | Ascometal Sa | STEEL FOR MAKING A WORKPIECE FOR BEARING |
| WO2000006790A1 (en) * | 1998-07-30 | 2000-02-10 | Ascometal | Steel for making a ball bearing part |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3374006B2 (en) | 2003-02-04 |
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