JP2622859B2 - Free-cutting tough steel with excellent fatigue strength - Google Patents

Free-cutting tough steel with excellent fatigue strength

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Publication number
JP2622859B2
JP2622859B2 JP16386888A JP16386888A JP2622859B2 JP 2622859 B2 JP2622859 B2 JP 2622859B2 JP 16386888 A JP16386888 A JP 16386888A JP 16386888 A JP16386888 A JP 16386888A JP 2622859 B2 JP2622859 B2 JP 2622859B2
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Japan
Prior art keywords
steel
fatigue strength
less
free
cutting
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JP16386888A
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Japanese (ja)
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JPH0215141A (en
Inventor
喬夫 大木
雅夫 内山
昌澄 大西
峯雄 荻野
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Toyota Motor Corp
Aichi Steel Corp
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Toyota Motor Corp
Aichi Steel Corp
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Description

【発明の詳細な説明】 ［産業上の利用分野］ 本発明は構造用部材、特に産業用車両のシャフト、足
回り部品等に用いられる疲労強度、焼入性、被削性に優
れた安価な強靭鋼に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is an inexpensive and excellent in fatigue strength, hardenability and machinability used for structural members, particularly shafts and undercarriage parts of industrial vehicles. It relates to tough steel.

［従来の技術］ 従来、産業車両のシャフト、足廻り部品等に用いられ
る構造用鋼としては、SCM440またはSCr440等の強靭鋼が
使用されていた。しかしながら、最近自動車に見られる
エンジン出力の増大により、従来に比べて高荷重下で使
用され、前記の従来材の耐久限が47kgf/mm2、硬さがHv2
90程度では疲労強度が若干不足するという問題が生じて
きた。また、従来材であるSCM440はMoを含有しているた
め、Mo資源の入手難と高騰により、コスト高になるとい
う問題があり、さらには両鋼種共に被削性が十分でなか
った。[Prior Art] Conventionally, as structural steel used for shafts, suspension parts and the like of industrial vehicles, tough steels such as SCM440 or SCr440 have been used. However, due to the increase in engine power recently seen in automobiles, it is used under higher loads than before, and the durability of the above-mentioned conventional materials is 47 kgf / mm 2 , and the hardness is Hv2
At about 90, there is a problem that the fatigue strength is slightly insufficient. In addition, since SCM440, which is a conventional material, contains Mo, there is a problem that the cost is increased due to the difficulty in obtaining and increasing the cost of Mo resources, and further, the machinability of both steel types was not sufficient.

［発明が解決しようとする課題］ 本発明は強靭鋼の前記のごとき問題点に鑑み、疲労強
度を改善し、省Mo化によりコストの低減を図るべくなさ
れたものであって、耐久限50kgf/mm2、硬さHv320程度で
疲労強度に優れ、かつ焼入性および切削性にも優れ、さ
らに高価なMoを含有せずコスト的に安価な強靭鋼を提供
することを目的とする。[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned problems of tough steel, in order to improve the fatigue strength and reduce the cost by saving Mo, and has a durability limit of 50 kgf / mm 2, excellent fatigue strength at about hardness Hv320, and also excellent in hardenability and cuttability, further an object to provide a cost-expensive tough steel does not contain expensive Mo.

［課題を解決するための手段］ 本発明者等は強靭鋼に及ぼす各種添加元素の影響につ
き鋭意研究を重ねた。その結果疲労強度を向上させるに
はＣおよびMn添加量を増加すること、また微量のＢを添
加することが効果的であることを見出だした。さらに、
Tiを添加すると共に、ＮおよびＯの含有量を低減し清浄
度を増し、Ti/Nの比を規制することにより、Ｂ添加の有
効性を確保し疲労強度の増加することを見出だした。そ
して、MnとＢの添加は同時に焼入性をも改善するもので
ある。さらに、被削性を改善するためＳ含有量を増加す
ると共にPbおよびCaを添加するものである。[Means for Solving the Problems] The present inventors have intensively studied the effects of various additive elements on the tough steel. As a result, it has been found that it is effective to increase the amounts of C and Mn added and to add a small amount of B to improve the fatigue strength. further,
It has been found that by adding Ti, the N and O contents are reduced to increase the cleanliness, and by regulating the Ti / N ratio, the effectiveness of B addition is ensured and the fatigue strength is increased. The addition of Mn and B simultaneously improves hardenability. Further, in order to improve the machinability, the S content is increased and Pb and Ca are added.

しかして、本発明は前記のごとき発明者等の新たな知
見に基づき完成されたものであって、本発明の第１発明
の疲労強度が優れた快削強靭鋼は、重量％でC;0.30〜0.
55％、Si;0.15〜0.35％、Mn;1.00〜2.00％、S;0.030％
以下、Cr;0.40％以下、Al;0.020％〜0.040％、B;0.0010
〜0.0040％、Ti;0.02〜0.05％、Pb;0.05〜0.30％、N;0.
0100％以下、O;0.0030％以下を含有し、Ti/Nが3.57以上
であり、残部がFeならびに不純物元素からなることを要
旨とする。Thus, the present invention has been completed based on the above-mentioned new knowledge of the inventors, and the free-cutting tough steel having excellent fatigue strength according to the first invention of the present invention has a C: 0.30% by weight. ~ 0.
55%, Si; 0.15-0.35%, Mn; 1.00-2.00%, S; 0.030%
Below; Cr; 0.40% or less; Al; 0.020% to 0.040%; B; 0.0010
-0.0040%, Ti; 0.02-0.05%, Pb; 0.05-0.30%, N;
The gist is that it contains 0100% or less, O; 0.0030% or less, Ti / N is 3.57 or more, and the balance consists of Fe and impurity elements.

また、第２発明の疲労強度が優れた快削強靭鋼は、重
量％でC;0.30〜0.55％、Si;0.15〜0.35％、Mn;1.00〜2.
00％、S;0.030％〜0.07％、Cr;0.40％以下、Al;0.020％
〜0.040％、B;0.0010〜0.0040％、Ti;0.02〜0.05％、P
b;0.05〜0.30％、N;0.0100％以下、O;0.0030％以下を含
有し、Ti/Nが3.57以上であり、残部がFeならびに不純物
元素からなることを要旨とする。The free-cutting tough steel having excellent fatigue strength according to the second aspect of the invention is, by weight%, C: 0.30 to 0.55%, Si: 0.15 to 0.35%, Mn: 1.00 to 2.
00%, S; 0.030% to 0.07%, Cr; 0.40% or less, Al; 0.020%
~ 0.040%, B; 0.0010-0.0040%, Ti; 0.02-0.05%, P
b; 0.05 to 0.30%, N: 0.0100% or less, O; 0.0030% or less, Ti / N is 3.57 or more, and the balance is composed of Fe and impurity elements.

さらに、第３発明の疲労強度が優れた快削強靭鋼は、
重量％でC;0.30〜0.55％、Si;0.15〜0.35％、Mn;1.00〜
2.00％、S;0.030％〜0.07％、Cr;0.40％以下、Al;0.020
％〜0.040％、B;0.0010〜0.0040％、Ti;0.02〜0.05％、
Pb;0.05〜0.30％、Ca;0.0005〜0.0100％、N;0.0100％以
下、O;0.0030％以下を含有し、Ti/Nが3.57以上であり、
残部がFeならびに不純物元素からなることを要旨とす
る。Further, the free-cutting tough steel having excellent fatigue strength according to the third invention is:
0.30 to 0.55% by weight, Si; 0.15 to 0.35%, Mn; 1.00 to
2.00%, S; 0.030% to 0.07%, Cr; 0.40% or less, Al; 0.020
% To 0.040%, B; 0.0010 to 0.0040%, Ti; 0.02 to 0.05%,
Pb; 0.05-0.30%, Ca; 0.0005-0.0100%, N; 0.0100% or less, O; 0.0030% or less, Ti / N is 3.57 or more,
The gist is that the balance consists of Fe and impurity elements.

［作用］ 本発明の疲労強度が優れた快削強靭鋼は、ＣおよびMn
量を増加することにより、疲労強度が向上している。ま
た、Ｂを添加することにより焼入性と併せて疲労強度の
向上が図られている。また、Tiの添加がさらに疲労強度
を増加させると共に、ＮおよびＯ量の上限を規制するこ
とにより鋼の清浄度を保ち、Ti/Nを規制することにより
Ｂ添加の有効性が確保される。さらに、Ｓ、PbおよびCa
の添加により、被削性が改善された。以下に本発明の成
分限定理由について説明する。[Action] The free-cutting tough steel having excellent fatigue strength according to the present invention comprises C and Mn.
By increasing the amount, the fatigue strength is improved. Further, by adding B, improvement in fatigue strength as well as hardenability is achieved. Further, the addition of Ti further increases the fatigue strength, maintains the cleanliness of the steel by regulating the upper limits of the amounts of N and O, and secures the effectiveness of the addition of B by regulating Ti / N. Further, S, Pb and Ca
Addition improved the machinability. Hereinafter, the reasons for limiting the components of the present invention will be described.

C:0.30〜0.55％ Ｃはシャフト等の構造部材として必要な疲労強度を得
るために0.30％以上が必要である。しかし、Ｃ含有量が
0.55％を越えると高周波焼入れ時に焼き割れが発生しや
すくなり、さらに切削等の加工性が悪くなるので上限を
0.55％とした。C: 0.30 to 0.55% C must be 0.30% or more in order to obtain the required fatigue strength as a structural member such as a shaft. However, the C content
If it exceeds 0.55%, quenching cracks are likely to occur during induction hardening, and workability such as cutting deteriorates.
0.55%.

Si;0.15〜0.35％ Siは製鋼時の脱酸のために0.15％以上が必要である。
しかし、0.35％を越えるとフェライトを強化して加工性
を害し、かつ酸化物系の介在物が増加するので、上限の
0.35％とした。Si: 0.15 to 0.35% Si needs to be 0.15% or more for deoxidation during steelmaking.
However, when the content exceeds 0.35%, the ferrite is strengthened and workability is impaired, and oxide-based inclusions increase.
0.35%.

Mn;1.00〜2.00％ Mnは疲労強度と焼入性を確保するために1.00％以上が
必要である。しかし、2.00％を越えて含有されると圧延
後の硬さが上昇し、シヤ切断時に割れが発生しやくな
り、切削性を害し、さらに焼なまし後の硬さが上昇する
等の欠点が出るので、上限を2.00％とした。Mn: 1.00 to 2.00% Mn needs to be 1.00% or more to ensure fatigue strength and hardenability. However, if it is contained in excess of 2.00%, the hardness after rolling will increase, cracks will easily occur during shear cutting, impairing machinability, and further increasing the hardness after annealing. Therefore, the upper limit was set to 2.00%.

Cr;0.40％以下 Crは焼入性を改善するために必要な元素であるが、0.
40％を越えるとその効果は飽和しコストも上昇するの
で、上限を0.40％とした。Cr: 0.40% or less Cr is an element necessary for improving hardenability.
If it exceeds 40%, the effect will be saturated and the cost will increase, so the upper limit was set to 0.40%.

S;0.030％以下 Ｓは切削性を改善するために必要な元素であるが、0.
03％を越えて添加すると清浄度を害し疲労強度を低下さ
せるので、上限を0.030％とした。S: 0.030% or less S is an element necessary for improving machinability,
When added in excess of 03%, the cleanliness is impaired and the fatigue strength is reduced, so the upper limit was made 0.030%.

B;0.0010〜0.0040％ Ｂは焼入性を改善するために添加されるが、0.0010％
未満であると充分な焼入性が得られず疲労強度が低下す
るので下限を0.0010％とした。しかし、0.0040％を越え
るとBCが粒界に生成し衝撃特性が低下するので、その上
限を0.0040％とした。B: 0.0010-0.0040% B is added to improve hardenability, but 0.0010%
If it is less than 30%, sufficient hardenability cannot be obtained and the fatigue strength decreases, so the lower limit was made 0.0010%. However, when the content exceeds 0.0040%, BC is formed at the grain boundary and the impact characteristics deteriorate, so the upper limit is made 0.0040%.

Pb;0.05〜0.30％ Pbは鋼中で微細なPb粒子として分散し、切削時には切
削工具と切断面との間に介在し、潤滑作用をなし摩擦係
数を減少するので、工具寿命を延ばし切削処理性が確保
される。この効果を得るためには0.05％以上添加するこ
とが必要である。しかし、0.30％を越えて添加される
と、清浄度を害し、疲労強度を低下させるので、上限を
0.30％とした。Pb; 0.05-0.30% Pb is dispersed as fine Pb particles in steel and intervenes between the cutting tool and the cut surface during cutting, which provides lubrication and reduces the coefficient of friction, extending tool life and cutting. Nature is secured. In order to obtain this effect, it is necessary to add 0.05% or more. However, if added in excess of 0.30%, the cleanliness is impaired and the fatigue strength is reduced.
0.30%.

Ti;0.02〜0.05％ TiはＮを固定しBNの生成を防止するために0.02％以上
が添加される。しかし、Tiの添加が0.05％を越えると清
浄度を害し却って疲労強度を低下させるので、上限を0.
05％以上とした。Ti: 0.02 to 0.05% Ti is added in an amount of 0.02% or more to fix N and prevent generation of BN. However, if the addition of Ti exceeds 0.05%, the cleanliness is impaired and the fatigue strength is reduced, so the upper limit is set to 0.
05% or more.

N;0.0100％以下 Ｎは不純物元素として鋼に含まれるが、多量に存在す
るとBNを生成しＢ添加の効果を無効果するので、その上
限を0.0100％とした。N; not more than 0.0100% N is contained in steel as an impurity element, but if present in a large amount, BN is formed and the effect of adding B is ineffective, so the upper limit was made 0.0100%.

Ti/N;3.57以上 Ti/NはＢの添加に影響を及ぼすＮがどれだけTiによっ
て固定されたかを示す数値であり、Ti/Nの比が3.57未満
であると有効Ｂの確保が困難となるのでその比の下限を
3.57とした。Ti / N: 3.57 or more Ti / N is a numerical value indicating how much N that affects the addition of B is fixed by Ti. If the ratio of Ti / N is less than 3.57, it is difficult to secure effective B. The lower limit of the ratio
3.57.

O;0.0030％以下 ＯはAl2O3、TiO2等の酸化物系の介在物を生成し、清
浄度を害するので、その上限を0.0030％とした。O: 0.0030% or less O generates oxide-based inclusions such as Al 2 O 3 and TiO 2 and impairs cleanliness. Therefore, the upper limit is made 0.0030%.

Al;0.020〜0.040％ Alは製鋼時の脱酸のためと結晶粒を微細化するために
0.020％以上が添加される。しかし、あまり多く添加す
ると清浄度を害するので、上限を0.040％とした。Al; 0.020-0.040% Al is used for deoxidation during steelmaking and for refining crystal grains.
0.020% or more is added. However, if too much is added, the cleanliness is impaired, so the upper limit was made 0.040%.

S;0.030〜0.070％ Ｓは鋼の被削性を向上させるのに効果的な元素であ
り、この効果を得るためには0.030％以上添加すること
が必要である。しかし、0.070％を越えて含有される
と、清浄度を害し疲労強度を低下させるため、上限を0.
070％とした。S: 0.030-0.070% S is an element effective for improving the machinability of steel, and it is necessary to add 0.030% or more to obtain this effect. However, if the content exceeds 0.070%, the cleanliness is impaired and the fatigue strength is reduced.
070%.

Ca;0.0005〜0.0100％ Caは微細な複合酸化物として介在し、切削を行うと工
具面に堆積して工具の寿命を向上させると共に疲労強度
を確保するために必要な元素である。この効果を得るた
めには0.0005％以上の添加が必要である。しかし、0.01
00％を越えて含有されると、複合酸化物が凝集して却っ
て疲労強度を低下させるので、上限を0.0100％とした。Ca; 0.0005 to 0.0100% Ca is an element necessary to intervene as a fine composite oxide, deposit on the tool surface when cutting is performed, improve the life of the tool, and secure fatigue strength. To obtain this effect, 0.0005% or more must be added. But 0.01
If the content exceeds 00%, the composite oxide will aggregate and rather reduce the fatigue strength, so the upper limit was made 0.0100%.

［実施例］ 次に本発明の特徴を従来鋼、比較鋼と比べて実施例で
もって明らかにする。[Examples] Next, the features of the present invention will be clarified by examples in comparison with conventional steels and comparative steels.

第１表はこれら供試鋼の化学成分を示すものである。
第１表において、供試鋼のＡ〜Ｆ鋼は第１発明の鋼、Ｇ
〜Ｈ鋼は第２発明の鋼、Ｉ〜Ｊ鋼は第３発明鋼である。
また、Ｋ鋼はSCr440に相当する従来鋼、Ｌ鋼は本発明鋼
の組成でPbを含有しない比較鋼、Ｍ鋼は本発明の組成で
Mn含有量だけが低い比較鋼、Ｎ鋼は本発明鋼の組成でＢ
含有量だけが低い比較鋼、Ｏ鋼は本発明鋼の組成でＮ含
有量が高くかつPbを含有しない比較鋼、Ｐ鋼は本発明の
組成でPb含有量の高い比較鋼である。Table 1 shows the chemical composition of these test steels.
In Table 1, the test steels A to F are steel of the first invention, G
Steels H to H are steels of the second invention, and I to J steels are steels of the third invention.
K steel is a conventional steel corresponding to SCr440, L steel is a comparative steel not containing Pb in the composition of the present invention steel, and M steel is a comparative steel not containing Pb in the composition of the present invention.
Comparative steel with only low Mn content, N steel
A comparative steel having only a low content, an O steel is a comparative steel having a high N content and no Pb in the composition of the steel of the present invention, and a P steel is a comparative steel having a high Pb content in the composition of the present invention.

第２表は第１表の供試鋼について硬さ、耐久限および
被削性を示したものである。硬さについては焼入れ焼戻
しした後ビッカース硬度（Hv）を測定し結果を第２表に
示した。耐久限については、小野式回転曲げ疲れ試験機
を用い測定した。 Table 2 shows the hardness, durability limit, and machinability of the test steels in Table 1. As for hardness, Vickers hardness (Hv) was measured after quenching and tempering, and the results are shown in Table 2. The durability limit was measured using an Ono-type rotary bending fatigue tester.

被削性については超硬工具を用いた工具寿命試験を行
った。工具寿命は硬さ（Hv）290の試料について切削速
度150m/分、切り込み深さ2.0mm、送り量0.20mm/revの条
件で切削し、工具の逃げ面平均摩耗幅Vaが0.3mmになる
までの時間分を測定した。結果は第２表に併せて示し
た。For machinability, a tool life test using a carbide tool was performed. The tool life is cut at a cutting speed of 150 m / min, a cutting depth of 2.0 mm, and a feed rate of 0.20 mm / rev on a sample with a hardness (Hv) of 290 until the average flank wear width Va of the tool becomes 0.3 mm. Time was measured. The results are shown in Table 2.

第２表から明らかなように、Mn含有量の低い比較例Ｍ
鋼、Ｂ含有量の低かった比較例Ｎ鋼、Ｎ含有量の高かっ
た比較例Ｏ鋼およびPb含有量の高い比較鋼Ｐのビッカー
ス硬さHv260から320の平滑耐久限は33.2〜47.8kgf/mm2
であり、切欠耐久限は12.0〜16.0kgf/mm2であって、SCr
440に相当する従来鋼であるＫ鋼の平滑耐久限45.0〜53.
0kgf/mm2、切欠耐久限15.5〜20.0kgf/mm2に比較して低
い値を示した。また、Pbを含有しなかった比較鋼Ｌ鋼お
よびＯ鋼の工具寿命は3.0および3.2であって、従来鋼の
7.0よりも劣った。 As is clear from Table 2, Comparative Example M having a low Mn content
The Vickers hardness of the steel, the comparative N steel having a low B content, the comparative steel O having a high N content and the comparative steel P having a high Pb content, and the smooth durability limit of Hv260 to 320 are 33.2 to 47.8 kgf / mm. Two
, And the notch endurance limit is a 12.0~16.0kgf / mm 2, SCr
Smooth durability limit of K steel, a conventional steel equivalent to 440, 45.0 to 53.
0 kgf / mm 2, showed a lower value than the notched durability limit 15.5~20.0kgf / mm 2. The tool life of the comparative steel L steel and O steel that did not contain Pb was 3.0 and 3.2, respectively.
Inferior to 7.0.

これに対して本発明鋼であるＡ〜Ｊ鋼は平滑耐久限で
43.0〜59.9kgf/mm2、切欠耐久限で15.5〜22.3kgf/mm2で
あって、従来鋼であるＫ鋼と同等またはそれ以上の耐久
限を示し、本発明の効果が確認された。さらに、切削性
については第１発明であるＡ〜Ｆ鋼で7.5〜10.5分Ｓ含
有量の高い第２発明であるＧ〜Ｈ鋼で13.2〜13.5分、Ca
を含有する第３発明であるＩ〜Ｊ鋼で20.0〜20.4分であ
って、従来鋼の7.0分に比較して優れた被削性を示すこ
とが確認された。In contrast, the steels A to J of the present invention have a smooth durability limit.
It was 43.0 to 59.9 kgf / mm 2 , with a notch durability limit of 15.5 to 22.3 kgf / mm 2 , showing a durability limit equal to or higher than that of conventional steel K, confirming the effects of the present invention. Further, regarding the machinability, 7.5 to 10.5 minutes for the A to F steels of the first invention, 13.2 to 13.5 minutes for the G to H steels of the second invention having a high S content,
It is 20.0 to 20.4 minutes for the I to J steels, which are the third inventions, and it has been confirmed that the steel exhibits excellent machinability compared to 7.0 minutes for the conventional steel.

［発明の効果］ 本発明の疲労強度の優れた強靭鋼は以上説明したよう
に、ＣおよびMn添加量を増加すると共に、微量のＢを添
加することにより疲労強度を改善したものである。ま
た、被削性改善元素であるＳ、PbおよびCaを添加するこ
とによって被削性が改善されており、さらに、Tiを添加
すると共に、ＮおよびＯの含有量を低減し清浄度を増
し、Ti/Nの比を規制することにより、Ｂ添加の有効性を
確保し、焼入性を改善するものであって、従来鋼よりも
優れた疲労強度と被削性を示すと共に、Cr量を低減しMo
の添加を省略できコストの低減化と省資源化が図れると
いう効果がある。[Effects of the Invention] As described above, the tough steel having excellent fatigue strength according to the present invention has improved fatigue strength by increasing the amounts of C and Mn added and adding a small amount of B. In addition, the machinability has been improved by adding the machinability improving elements S, Pb, and Ca, and further, while adding Ti, reducing the content of N and O to increase the cleanliness, By regulating the Ti / N ratio, the effectiveness of the addition of B is ensured and the hardenability is improved.It exhibits superior fatigue strength and machinability compared to conventional steel, and reduces the amount of Cr. Reduced Mo
Has the effect of reducing the cost and saving resources.

フロントページの続き (72)発明者 大西 昌澄 愛知県豊田市トヨタ町１番地 トヨタ自 動車株式会社内 (72)発明者 荻野 峯雄 愛知県豊田市トヨタ町１番地 トヨタ自 動車株式会社内 (56)参考文献 特開 昭61−257457（ＪＰ，Ａ)Continued on the front page (72) Inventor Masami Onishi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Mineo Ogino 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References JP-A-61-257457 (JP, A)

Claims (3)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】重量％でC;0.30〜0.55％、Si;0.15〜0.35
％、Mn;1.00〜2.00％、S;0.030％以下、Cr;0.40％以
下、Al;0.020％〜0.040％、B;0.0010〜0.0040％、Ti;0.
02〜0.05％、Pb;0.05〜0.30％、N;0.0100％以下、O;0.0
030％以下を含有し、Ti/Nが3.57以上であり、残部がFe
ならびに不純物元素からなることを特徴とする疲労強度
が優れた快削強靭鋼。(1) C: 0.30 to 0.55% by weight, Si; 0.15 to 0.35
%, Mn; 1.00 to 2.00%, S; 0.030% or less, Cr; 0.40% or less, Al; 0.020% to 0.040%, B; 0.0010 to 0.0040%, Ti;
02-0.05%, Pb; 0.05-0.30%, N; 0.0100% or less, O; 0.0
030% or less, Ti / N is 3.57 or more, the balance is Fe
A free-cutting tough steel with excellent fatigue strength, characterized by being made of impurity elements. 【請求項２】重量％でC;0.30〜0.55％、Si;0.15〜0.35
％、Mn;1.00〜2.00％、S;0.030％〜0.07％、Sr;0.40％
以下、Al;0.020％〜0.040％、B;0.0010〜0.0040％、Ti;
0.02〜0.05％、Pb;0.05〜0.30％、N;0.0100％以下、O;
0.0030％以下を含有し、Ti/Nが3.57以上であり、残部が
Feならびに不純物元素からなることを特徴とする疲労強
度が優れた快削強靭鋼。2. C: 0.30 to 0.55% by weight, Si: 0.15 to 0.35% by weight
%, Mn; 1.00-2.00%, S; 0.030% -0.07%, Sr; 0.40%
Below, Al; 0.020% to 0.040%, B; 0.0010 to 0.0040%, Ti;
0.02-0.05%, Pb; 0.05-0.30%, N; 0.0100% or less, O;
0.0030% or less, Ti / N is 3.57 or more, the balance is
Free-cutting tough steel with excellent fatigue strength characterized by Fe and impurity elements. 【請求項３】重量％でC;0.30〜0.55％、Si;0.15〜0.35
％、Mn;1.00〜2.00％、S;0.030％〜0.07％、Cr;0.40％
以下、Al:0.02％〜0.040％、B;0.0010〜0.0040％、Ti;
0.02〜0.05％、Pb;0.05〜0.30％、Ca;0.0005〜0.0100
％、N;0.0100％以下、O;0.0030％以下を含有し、Ti/Nが
3.57以上であり、残部がFeならびに不純物元素からなる
ことを特徴とする疲労強度が優れた快削強靭鋼。3. C: 0.30 to 0.55% by weight, Si; 0.15 to 0.35% by weight
%, Mn; 1.00-2.00%, S; 0.030% -0.07%, Cr; 0.40%
Below, Al: 0.02% to 0.040%, B; 0.0010 to 0.0040%, Ti;
0.02-0.05%, Pb; 0.05-0.30%, Ca; 0.0005-0.0100
%, N; 0.0100% or less, O; 0.0030% or less, Ti / N
A free-cutting tough steel with excellent fatigue strength characterized by being 3.57 or more, with the balance being Fe and impurity elements.
JP16386888A 1988-06-30 1988-06-30 Free-cutting tough steel with excellent fatigue strength Expired - Lifetime JP2622859B2 (en)

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JP2622859B2 true JP2622859B2 (en) 1997-06-25

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Publication number Priority date Publication date Assignee Title
JP2725747B2 (en) * 1990-11-16 1998-03-11 大同特殊鋼株式会社 Steel for induction hardening

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