JPH0133544B2 - - Google Patents
Info
- Publication number
- JPH0133544B2 JPH0133544B2 JP9350180A JP9350180A JPH0133544B2 JP H0133544 B2 JPH0133544 B2 JP H0133544B2 JP 9350180 A JP9350180 A JP 9350180A JP 9350180 A JP9350180 A JP 9350180A JP H0133544 B2 JPH0133544 B2 JP H0133544B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- inclusions
- machinability
- cold forgeability
- less
- 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
Links
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 10
- 229910052745 lead Inorganic materials 0.000 claims description 10
- 229910052797 bismuth Inorganic materials 0.000 claims description 9
- 229910000746 Structural steel Inorganic materials 0.000 claims description 8
- 229910000831 Steel Inorganic materials 0.000 description 23
- 239000010959 steel Substances 0.000 description 23
- 238000012360 testing method Methods 0.000 description 11
- 238000005520 cutting process Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- 229910000915 Free machining steel Inorganic materials 0.000 description 3
- 238000010273 cold forging Methods 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 238000005482 strain hardening Methods 0.000 description 3
- 229910000851 Alloy steel Inorganic materials 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 2
- 229910000532 Deoxidized steel Inorganic materials 0.000 description 2
- 239000010962 carbon steel Substances 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 150000003568 thioethers Chemical class 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 229910045601 alloy Chemical class 0.000 description 1
- 239000000956 alloy Chemical class 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000010730 cutting oil Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910001678 gehlenite Inorganic materials 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000002184 metal Chemical class 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
Description
本発明は、冷間鍛造性と被削性の優れた機械構
造用鋼に関するものである。
従来より機械部品の多くは切削加工によつて製
作されているが、近年、冷間加工技術の進歩とと
もに、部品の加工費を削減するために、まず、冷
間加工によつて粗成形し、その後、仕上げのため
切削加工を行なうという工程を多く採用されつつ
ある。そのために、鋼材に対しては冷間鍛造性と
被削性との両特性を有するものが要求されてきて
いる。
そして、従来においては冷間鍛造性を良好にす
るため球状化焼なまし処理や鋼材の清浄度を低く
する方法がとられているが、この方法では鋼材の
切削時の被削性が悪くなり、また、被削性を改善
するために、ＳやPbを添加する方法が採用され
ているが、鋼材の冷間鍛造性が悪くなる。このよ
うに、冷間鍛造性と被削性とは相反する場合が多
く、両立させることは困難であるといわれてい
る。
また、一般に、機械構造用炭素鋼や合金鋼は、
Ｓを0.015〜0.030％程度含有されており、このＳ
は殆んどがMnSの形で鋼中に存在している。そ
して、このMnSは不均一に多く分布しており、
圧延時に長く展伸するため機械的性質の異方性を
生じたり、冷間鍛造性を劣化させる（このような
鋼中介在物をJIS規格ではＡ系介在物という。）ま
た、Alは溶鋼の脱酸や結晶粒度調整のために添
加するのであるが、溶鋼の凝固後においても
Al2O3の形で約40〜100ppm程度含有されており、
冷間加工時の割れの起点となつて、冷間圧造性を
悪化させたり、硬質のため切削時の工具摩耗を促
進させたりする（このような鋼中介在物をJIS規
格ではＢ系介在物という。）
次に、従来のCa脱酸鋼、鉛快削鋼について説
明すると、先づ、Ca脱酸鋼は溶鋼をCa脱酸し、
アノルサイト（CaO・Al2O3・2SiO2）、ゲーレナ
イト（2CaO・Al2O3・SiO2）等のCa酸化物を生
成させることによつて切削時の工具表面にベラー
グ（Belag）と称する付着物を形成させ工具摩耗
を抑制することのできる鋼である。また、Ca脱
酸鋼にはCa酸化物をCaO・nAl2O3とする鋼もあ
る。次いで、鉛快削鋼は、Pbが0.15〜0.30％含有
されており、そして、このPbは単独介在物や硫
化物との複合介在物、酸化物との複合介在物の形
で存在している。このPb介在物は切削時に応力
集中効果や工具との潤滑作用により被削性を改善
する。しかし、一般の鉛快削鋼、例えばS45CLの
Ｓ含有量は0.015〜0.030％であり、その殆んどが
MnSの形で存在しており、そして、このMnSは
圧延時に展伸してＡ系介在物となり、また、Pb
は大きなMnSとの複合介在物とするので冷間鍛
造性を悪化させる。
本発明は、上記に説明した従来技術においては
冷間鍛造性と被削性とを有する機械構造用鋼を得
ることができなかつた困難な問題を解決したもの
であつて、Ca、Ｓ、Pb、Biを適正量に調整し、
かつ、介在物を適切な形態や微細に分散させるこ
とにより冷間鍛造性と被削性の両特性を向上させ
た機械構造用鋼である。
そして、本発明に係る機械構造用鋼において
は、上記した冷間鍛造性と被削性との両特性を得
るために、溶鋼中にCaを多量に連続的に添加し、
溶存しているＳをCaSに変化させ、また、Caに
よる還元反応によつてAl2O3をなくすか、また、
極めて少なくした。即ち、反応式で示すと次式の
ようになる。
Ca＋Ｓ→CaS
3Ca＋Al2O3→3CaO＋2Al
この結果、介在物はCaS−CaO系となり、か
つ、微細に均一に分散する。その後、Pb、Biの
一種又は２種を化合物、金属、合金の何れかの形
態で少量添加含有させて、Pb又はBiの単独介在
物を生成させたり、或いは、CaS−CaO（このよ
うな鋼中介在物をJIS規格ではＣ系介在物とい
う。）の周辺に微細に析出させることによつて、
有害な介在物を除去したり、或いは、介在物の形
態を制御したりし、さらに、微細に分散させるこ
とにより、これらの作用及び／又は効果が相乗的
に働き、冷間鍛造性と被削性とを向上させたもの
である。従つて、MnSが圧延時に展伸するとい
うこともなく、また、有害なAl2O3も著しく少な
くなるのである。
次に、本発明に係る冷間鍛造性と被削性の優れ
た機械構造用鋼について、含有成分、成分割合及
び介在物について詳細に説明する。なお、機械構
造用鋼には、機械構造用炭素鋼、機械構造用合金
鋼が含まれこれらはおおむねC0.6％以下、Si0.35
％以下、Mn1.8％以下と必要に応じてCr1.2％以
下、Mo0.3％以下、Ni5％以下を含むものであ
る。
Caは、これが含有されることによつて種々の
硫化物や酸化物が生成し、介在物をCaS−CaOと
し、Al2O3を還元して著しく減少させる。よつて
Caを溶鋼に多量に添加する必要があるが、製品
段階におけるCa含有量が0.002％未満ではこの効
果が少なく、0.05％を越えて含有されるとCaOの
介在物が多くなり冷間鍛造性が悪くなる。従つ
て、Ca含有量は0.001〜0.05％の範囲とする。
Ｓは、0.005％を越えて含有されていると、
CaSばかりでなく、MnSが多くなり冷間鍛造性
を悪化させる。よつて、Ｓ含有量は0.005％以下
とするのである。
Pb、Biは被削性を向上させる元素であり、
Pb、Biの一種、又は、二種の含有量が0.02％未
満では被削性の向上の効果は少なく、また、0.15
％を越えて含有されるとPb、Biの単独の介在物
が大きくなつて冷間鍛造性を悪化させる。よつ
て、Pb、Biの単独、又は複合の含有量は0.02〜
0.15％とする。
CaS−CaO、PB、Bi系の介在物としたのは、
CaS−CaOがMnSより圧延時に変形し難く、ま
た、均一に微細に分散する傾向があるため、機械
的性質の異方性が少なく、冷間鍛造性が良くなり
被削性を向上させるからである。なお、含有して
いるＳの全部をCaSの介在物にする必要はなく、
Ｓ含有量の0.005％以下における範囲内で生成さ
れる若干量のMnSは許容される。
また、Al2O3は硬質であるから切削時の工具の
摩耗を促進し被削性を悪化させるとともに、冷間
鍛造時における割れ発生の起点となる。よつて、
このAl2O3は少ない程望ましいものであるが、技
術的に、含有量は0.001％未満とするのである。
次に、本発明に係る冷間鍛造性と被削性の優れ
た機械構造用鋼の実施例について説明する。
実施例
60屯実用炉で第１表に示す成分、成分割合とな
るように溶製し、切削試験用と冷間圧造試験用に
それぞれ80φ25φの丸棒に圧延した。焼ならし処
理後両試験を実施した。なお、第１表において、
Ａ，Ｂは本発明に係る鋼、Ｃ，Ｄ，Ｅは比較鋼で
ある。
The present invention relates to a steel for machine structures that has excellent cold forgeability and machinability. Conventionally, many mechanical parts have been manufactured by cutting, but in recent years, with advances in cold working technology, in order to reduce the processing costs of parts, they are first roughly formed by cold working. After that, a process of cutting for finishing is increasingly being adopted. For this reason, steel materials are required to have both cold forgeability and machinability. Conventionally, in order to improve cold forgeability, methods such as spheroidizing annealing or lowering the cleanliness of the steel material have been used, but this method deteriorates the machinability of the steel material during cutting. Also, in order to improve machinability, a method of adding S or Pb has been adopted, but the cold forgeability of the steel material deteriorates. As described above, cold forgeability and machinability are often contradictory, and it is said that it is difficult to achieve both. In general, carbon steel and alloy steel for machine structures are
Contains about 0.015 to 0.030% of S.
is present in steel mostly in the form of MnS. This MnS is unevenly distributed,
Because Al is stretched for a long time during rolling, it causes anisotropy in mechanical properties and deteriorates cold forgeability (such inclusions in steel are called A-based inclusions in JIS standards). It is added to deoxidize and adjust grain size, but even after solidification of molten steel,
Contains about 40 to 100 ppm in the form of Al 2 O 3 ,
They act as starting points for cracks during cold working, worsening cold forging properties, and accelerate tool wear during cutting due to their hardness (such inclusions in steel are classified as B-type inclusions according to JIS standards). ) Next, to explain conventional Ca-deoxidized steel and lead free-cutting steel, first, Ca-deoxidized steel deoxidizes molten steel with Ca,
By generating Ca oxides such as anorsite (CaO・Al 2 O 3・2SiO 2 ) and gehlenite (2CaO・Al 2 O 3・SiO 2 ), an adhesion called Belag is formed on the tool surface during cutting. It is a steel that can form a kimono and suppress tool wear. Furthermore, some Ca-deoxidized steels have CaO.nAl 2 O 3 as their Ca oxide. Next, lead free-cutting steel contains 0.15 to 0.30% Pb, and this Pb exists in the form of single inclusions, composite inclusions with sulfides, and composite inclusions with oxides. . These Pb inclusions improve machinability during cutting due to stress concentration effects and lubrication with the tool. However, the S content of general lead free-cutting steel, such as S45CL, is 0.015 to 0.030%, and most of it is
It exists in the form of MnS, and this MnS is expanded during rolling to become A-based inclusions, and Pb
Since it forms composite inclusions with large MnS, it deteriorates cold forgeability. The present invention solves the difficult problem of not being able to obtain mechanical structural steel with cold forgeability and machinability using the conventional techniques described above. , adjust Bi to an appropriate amount,
In addition, it is a mechanical structural steel with improved cold forgeability and machinability properties by dispersing inclusions in an appropriate form and finely. In the machine structural steel according to the present invention, in order to obtain both the properties of cold forgeability and machinability described above, a large amount of Ca is continuously added to the molten steel,
Either converting dissolved S into CaS and eliminating Al 2 O 3 through a reduction reaction with Ca, or
It was extremely small. That is, the reaction formula is as follows. Ca+S→CaS 3Ca+Al 2 O 3 →3CaO+2Al As a result, the inclusions become a CaS-CaO system and are finely and uniformly dispersed. After that, a small amount of one or both of Pb and Bi in the form of a compound, metal, or alloy is added to form a single Pb or Bi inclusion, or CaS-CaO (such as steel By causing fine precipitation around the intermediate inclusions (called C-based inclusions in JIS standards),
By removing harmful inclusions, controlling the morphology of inclusions, and further finely dispersing them, these actions and/or effects work synergistically to improve cold forgeability and machinability. It has improved characteristics. Therefore, MnS does not expand during rolling, and harmful Al 2 O 3 is significantly reduced. Next, the contained components, component ratios, and inclusions of the mechanical structural steel with excellent cold forgeability and machinability according to the present invention will be explained in detail. Note that mechanical structural steel includes carbon steel for mechanical structural use and alloy steel for mechanical structural use, which generally have C0.6% or less and Si0.35.
% or less, Mn 1.8% or less, and optionally Cr 1.2% or less, Mo 0.3% or less, and Ni 5% or less. When Ca is contained, various sulfides and oxides are generated, and inclusions become CaS-CaO, which reduces Al 2 O 3 and significantly reduces it. Sideways
It is necessary to add a large amount of Ca to molten steel, but if the Ca content in the product stage is less than 0.002%, this effect will be small, and if it exceeds 0.05%, CaO inclusions will increase and cold forgeability will deteriorate. Deteriorate. Therefore, the Ca content should be in the range of 0.001 to 0.05%. If S is contained in excess of 0.005%,
Not only CaS but also MnS increases, which deteriorates cold forgeability. Therefore, the S content is set to 0.005% or less. Pb and Bi are elements that improve machinability.
If the content of one or both of Pb and Bi is less than 0.02%, the effect of improving machinability is small;
If the content exceeds %, individual inclusions of Pb and Bi become large and deteriorate cold forgeability. Therefore, the content of Pb and Bi alone or in combination is 0.02~
The rate shall be 0.15%. The CaS-CaO, PB, and Bi-based inclusions were
This is because CaS-CaO is less deformable during rolling than MnS and tends to be uniformly and finely dispersed, so there is less anisotropy in mechanical properties, which improves cold forgeability and machinability. be. It should be noted that it is not necessary to make all of the contained S into CaS inclusions;
Some amount of MnS produced within the range of 0.005% or less of S content is acceptable. Furthermore, since Al 2 O 3 is hard, it accelerates tool wear during cutting, worsening machinability, and becomes a starting point for cracking during cold forging. Then,
Although it is desirable to have as little Al 2 O 3 as possible, technically the content should be less than 0.001%. Next, an example of a mechanical structural steel having excellent cold forgeability and machinability according to the present invention will be described. Example: Molten products were melted in a 60-ton practical furnace to have the components and component ratios shown in Table 1, and rolled into round bars of 80 φ and 25 φ for cutting tests and cold heading tests, respectively. Both tests were conducted after normalizing treatment. In addition, in Table 1,
A and B are steels according to the present invention, and C, D, and E are comparative steels.
【表】
(1) 冷間鍛造試験
試験片 20φ×30mm
この試験片の拘束圧縮を行ない、割れ亀裂が
生じた時の限界すえ込み率を求めた。この限界
すえ込み率の大きい鋼ほど冷間鍛造性は良好で
ある。即ち、限界すえ込み率は次式により計算
する。
限界すえ込み率＝Ho−Ｈ／Ho×100（％）
Ho：試験片の圧縮前の高さ。
Ｈ：試験片を拘束圧縮して割れが発生した
時の試験片の高さ。
(2) 切削試験
切削速度：50、100、150、200、250（ｍ／
min）
送 り：0.05、0.125、0.175、0.25（mm／rev）
切込み：1.5mm（一定）
切削油：無し
この20条件について旋盤で超硬工具p10によ
る旋削を行ない生成する切粉の形態によつて切
りくず処理性の評価点を与えた。
切粉の形態 評価点
細かく１巻き以下に分断 40点
２〜３巻き 30点
規則的連続してカール 20点
カールせず不規則 10点
そして、20条件について合計した。切りくず処
理性の評価点の高い程被削性が優れているのであ
る。
この冷間鍛造性と被削性の試験結果を添付図面
に示す。この添付図面より明らかであるが、比較
鋼、Ｃ，Ｅは冷間鍛造性、被削性共に本発明に係
る鋼より著しく劣つているものである。また、比
較鋼Ｄは被削性は本発明に係る鋼より良好である
が、冷間鍛造性は本発明に係る鋼より相当に悪い
のである。
以上説明したように、本発明に係る冷間鍛造性
と被削性の優れた機械構造用鋼は上記の構成を有
しているものであるから、冷間鍛造性、被削性と
の両特性の極めて優れた効果を有している。[Table] (1) Cold forging test Test piece 20φ x 30mm This test piece was subjected to restraint compression, and the critical swaging rate at which cracking occurred was determined. Steels with a larger critical swaging ratio have better cold forgeability. That is, the limit swaging rate is calculated using the following formula. Limit swaging rate = Ho-H/Ho x 100 (%) Ho: Height of test piece before compression. H: Height of the test piece when cracking occurs when the test piece is restrained and compressed. (2) Cutting test Cutting speed: 50, 100, 150, 200, 250 (m/
min) Feed: 0.05, 0.125, 0.175, 0.25 (mm/rev) Depth of cut: 1.5 mm (constant) Cutting oil: None Regarding these 20 conditions, turning is performed on a lathe using a carbide tool P10, and the shape of the chips generated is An evaluation score was given for chip control. Form of chips Evaluation points Finely divided into one or less turns 40 points 2 to 3 turns 30 points Regularly and continuously curling 20 points Irregular without curling 10 points Then, totals were calculated for 20 conditions. The higher the chip control evaluation score, the better the machinability. The test results of cold forgeability and machinability are shown in the attached drawings. As is clear from the accompanying drawings, comparative steels C and E are significantly inferior to the steel according to the present invention in both cold forgeability and machinability. Furthermore, although comparative steel D has better machinability than the steel according to the present invention, its cold forgeability is considerably worse than the steel according to the present invention. As explained above, since the machine structural steel of the present invention having excellent cold forgeability and machinability has the above structure, it has both cold forgeability and machinability. It has extremely excellent properties and effects.
添付図面は冷間鍛造性と被削性とを示すグラフ
である。
The attached drawing is a graph showing cold forgeability and machinability.
Claims (1)
て0.02〜0.15％含有し、Ｓを0.005％以下に規制
し、介在物をCaS―CaO、Pb、Bi系介在物とし、
かつ、Al2O3介在物を0.001％未満に抑えたことを
特徴とする冷間鍛造性と被削性の優れた機械構造
用鋼。1 Contains 0.002 to 0.05% of Ca, 0.02 to 0.15% of Pb and Bi alone or in combination, regulates S to 0.005% or less, and makes inclusions CaS-CaO, Pb, Bi-based inclusions,
A mechanical structural steel with excellent cold forgeability and machinability, characterized by suppressing Al 2 O 3 inclusions to less than 0.001%.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9350180A JPS5719366A (en) | 1980-07-09 | 1980-07-09 | Machine structural steel with superior cold forgeability and machinability |
| DE3126984A DE3126984A1 (en) | 1980-07-09 | 1981-07-08 | Steel for mechanical engineering, having excellent cold-forgeability and machinability |
| US06/281,675 US4431445A (en) | 1980-07-09 | 1981-07-09 | Steel for machine construction having excellent cold forgeability and machinability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9350180A JPS5719366A (en) | 1980-07-09 | 1980-07-09 | Machine structural steel with superior cold forgeability and machinability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5719366A JPS5719366A (en) | 1982-02-01 |
| JPH0133544B2 true JPH0133544B2 (en) | 1989-07-13 |
Family
ID=14084089
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9350180A Granted JPS5719366A (en) | 1980-07-09 | 1980-07-09 | Machine structural steel with superior cold forgeability and machinability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5719366A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0745695B2 (en) * | 1987-07-17 | 1995-05-17 | 株式会社神戸製鋼所 | Method for manufacturing shaft-shaped component that is induction hardened after cold forging |
| JP2648667B2 (en) * | 1995-05-22 | 1997-09-03 | ヤマハ発動機株式会社 | Small boat |
| WO2023017829A1 (en) | 2021-08-10 | 2023-02-16 | 日本製鉄株式会社 | Steel material |
-
1980
- 1980-07-09 JP JP9350180A patent/JPS5719366A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5719366A (en) | 1982-02-01 |
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