JPH0784612B2 - Melting method of Ca free-cutting steel - Google Patents
Melting method of Ca free-cutting steelInfo
- Publication number
- JPH0784612B2 JPH0784612B2 JP6368991A JP6368991A JPH0784612B2 JP H0784612 B2 JPH0784612 B2 JP H0784612B2 JP 6368991 A JP6368991 A JP 6368991A JP 6368991 A JP6368991 A JP 6368991A JP H0784612 B2 JPH0784612 B2 JP H0784612B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- inclusions
- free
- composition
- 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 - Lifetime
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- Treatment Of Steel In Its Molten State (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は鋼の被削性を改善するこ
とを目的として溶鋼にＣａを添加するＣａ快削鋼の溶製
方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing Ca free-cutting steel in which Ca is added to molten steel for the purpose of improving machinability of steel.
【０００２】[0002]
【従来の技術】従来、鋼材の被削性に及ぼす介在物組成
の影響については、例えば「第９６・９７回西山記念講
座、昭和５９年２月１５・１６日、日本鉄鋼協会」Ｐ４
２、表６によれば、被削性に及ぼす介在物の影響を被削
性に好ましい介在物と好ましくない介在物に分けて整理
して述べられている。この中で、Ｃａ成分を含む好まし
い介在物としてＣａＯ・Ａｌ２Ｏ３・２ＳｉＯ２（アノ
ーサイト）、２ＣａＯ・Ａｌ２Ｏ３・ＳｉＯ２（ゲーレ
ナイト）を挙げている。また、同上文献のＰ１７５〜１
７７には、Ｃａ脱酸鋼で生成された介在物をＣａＯ−Ａ
ｌ２Ｏ３−ＳｉＯ２三元系であるとし、良好な工具寿命
が得られる付着物組成を三元状態図の中で示し、最も多
く報告されているものはＡおよびＢのアノーサイトとゲ
ーレナイトであると記述されている。一方、「電気製
鋼」４４（１９７３）１，Ｐ８３によれば、Ｃａ快削鋼
中の含Ｃａ脱酸生成物はアノーサイト、ゲーレナイトの
領域を中心としたものが多いと報告され、さらにその結
果鍛延方向に長伸したいわゆるＡ２系介在物となってお
り、工具寿命曲線からこの延伸したＡ２系介在物組成が
球状のＣ系介在物より工具寿命の長寿命化をもたらすと
報告されている。また、Ｃａ脱酸鋼の介在物組成の制御
に関する公知文献、あるいは特開昭６２−１９９７４９
号公報のようなＣａ−Ｓ系快削鋼の連続鋳造に関するも
のは見られるが、Ｃａ脱酸鋼の被削性向上のため目標と
する介在物組成を実現するための製造技術に関する一貫
した公知技術は存在していない。2. Description of the Related Art Conventionally, for the influence of inclusion composition on the machinability of steel materials, see, for example, "96th and 97th Nishiyama Memorial Lecture, February 15th and 16th, 1984, Iron and Steel Institute of Japan" p.
According to Table 2 and Table 6, the influence of inclusions on machinability is classified into inclusions that are preferable for machinability and inclusions that are not preferable for machinability. Among these, CaO.Al 2 O 3 .2SiO 2 (anorthite) and 2CaO.Al 2 O 3 .SiO 2 (gerenite) are mentioned as preferred inclusions containing a Ca component. Moreover, P175-1 of the above-mentioned document
In 77 , inclusions generated in Ca deoxidized steel are CaO-A.
1 2 O 3 -SiO 2 ternary system, the composition of the deposit that gives a good tool life is shown in the ternary phase diagram, and the most commonly reported one is the anorthite of A and B and the grenite. Is described. On the other hand, according to "Electrical Steelmaking" 44 (1973) 1, P83 , it is reported that Ca-containing deoxidation products in Ca free-cutting steel are mainly in the anorthite and gerhenite regions. It is a so-called A 2 type inclusion that is elongated in the forging direction, and it is reported from the tool life curve that this stretched A 2 type inclusion composition results in a longer tool life than a spherical C type inclusion. ing. Also, there are known documents concerning the control of the composition of inclusions in Ca-deoxidized steel, or JP-A-62-199749.
Although there is something related to continuous casting of Ca-S free-cutting steel as in Japanese Patent Publication, there is a consistent public knowledge about a manufacturing technique for realizing a target inclusion composition for improving the machinability of Ca-deoxidized steel. There is no technology.
【０００３】[0003]
【発明が解決しようとする課題】本発明は、 鋼の被削
性を向上させるために必要とされる鋼中の非金属介在物
を、Ｃａ脱酸鋼としての製造過程において、目標とする
介在物組成を実現する鋼の溶製技術であり、鋼材中の好
ましい介在物組成とされているアノーサイトやゲーレナ
イトをより安定して具現せしめるものである。DISCLOSURE OF THE INVENTION The present invention aims to eliminate the non-metallic inclusions in the steel, which are required for improving the machinability of the steel, in the production process as Ca-deoxidized steel. It is a melting technology for steel that realizes a material composition, and more stably embodies anorthite and gehlenite, which are preferable inclusion compositions in steel materials.
【０００４】[0004]
【課題を解決するための手段】本発明は被削性を要求さ
れるＣａ脱酸鋼の製造、すなわち、鋼の被削性向上を目
的として溶鋼にＣａを添加するＣａ快削鋼の溶製方法に
おいて、鋼浴中の全Ａｌ含有量を０．００２％以下と
し、次いでＣａを添加する際にこの溶鋼を保持する溶鋼
容器内のスラグ塩基度ＶおよびＣａの添加量Ｗにより下
記（１）式で定められる操業インデックスＩを下記
（２）式の範囲に制御してＣａを添加することを特徴と
するＣａ快削鋼の溶製方法である。 Ｉ＝１／Ｗ・Ｖ ・・・・・（１） ４≦Ｉ≦１６ ・・・・・（２） 但し、Ｗ：溶鋼中に添加するＣａまたはＣａ合金のＣａ
換算原単位（ｋｇ／Ｔｏｎ） Ｖ：スラグの塩基度 （％ＣａＯ）／（％ＳｉＯ2） 図１は、Ｃａを添加する場合の操業インデックスＩとそ
の結果得られた鋼材（ビレット）中の介在物のアスペク
ト比の関係を表す図表であり、図２は、Ｃａ脱酸鋼の鋼
中の全Ａｌ量（以下Ｔ．Ａｌという）と介在物中のＡｌ
2Ｏ3の関係を表した図表で、いずれも、本発明者等によ
る実験の結果得られたものである。この発明において、
Ｃａ快削鋼は基本成分の含有量、および合金元素の含有
量は特別に限定する必要はないが、被削性の良好な介在
物を作り込むため、まず、Ｔ．Ａｌを以下の通り限定す
る。目標介在物中のＡｌ2Ｏ3濃度は１５〜３０％であ
り、このＡｌ2Ｏ3濃度に対応するＴ．Ａｌは図２から
０．００２％が上限であるからこれを上限とする。The present invention is directed to the production of Ca deoxidized steel requiring machinability, that is, the production of Ca free-cutting steel in which Ca is added to molten steel for the purpose of improving the machinability of steel. In the method, the total Al content in the steel bath is set to 0.002% or less, and when the Ca is added next, the slag basicity V in the molten steel container holding the molten steel and the addition amount W of the Ca given below (1) A Ca free-cutting steel melting method is characterized in that Ca is added by controlling an operation index I defined by the formula within the range of the following formula (2). I = 1 / W · V (1) 4 ≦ I ≦ 16 (2) where W: Ca added to the molten steel or Ca of Ca alloy
Conversion unit (kg / Ton) V: Basicity of slag (% CaO) / (% SiO 2 ) FIG. 1 shows the operation index I when Ca is added and the interposition in the resulting steel material (billet). 2 is a chart showing the relationship of the aspect ratio of the object, and FIG. 2 shows the total Al amount in the steel of Ca deoxidized steel (hereinafter referred to as T.Al) and the Al in the inclusions.
2 is a diagram showing the relationship of 2 O 3 , which is obtained as a result of experiments by the present inventors. In this invention,
In Ca free-cutting steel, the contents of basic components and the contents of alloying elements do not need to be specifically limited, but since inclusions having good machinability are built in, the T. Al is limited as follows. Concentration of Al 2 O 3 target inclusions is 15 to 30%, T. corresponding to the concentration of Al 2 O 3 Since the upper limit of Al is 0.002% from FIG. 2, this is the upper limit.
【０００５】また、操業インデックスＩにおいて、 適
正な取鍋スラグの塩基度Ｖの範囲は０．７〜１．５であ
る。Ｖ＜０．７の場合には取鍋耐火物の損傷が大きく工
業的には得策ではない。またＶ＞１．５の場合は、Ｃａ
Ｏが過大となり、好ましい介在物を鋼中に存在せしめる
ことができない。操業インデックスＩ≧４ではゲーレナ
イトに、Ｉ≧８ではアノーサイトに制御できる。Ｃａ添
加量Ｗについてはこれがゼロに近い場合は操業インデッ
クスは大となるが、介在物の大部分はＳｉＯ2系とな
り、好ましい介在物とはならないので注意を要する。Ｃ
ａ添加量Ｗは、Ｗ≧０．０８ｋｇ／Ｔｏｎの範囲で適用
できる。以上から操業インデックスＩの上限はＩ＝１６
程度まで実用可能である。Further, in the operation index I, the range of the basicity V of the appropriate ladle slag is 0.7 to 1.5. When V <0.7, the ladle refractory is damaged greatly and is not industrially advantageous. If V> 1.5, Ca
O becomes too large and preferable inclusions cannot be present in the steel. When the operation index is I ≧ 4, it can be controlled to Gerenite, and when I ≧ 8, it can be controlled to anorthite. When the Ca addition amount W is close to zero, the operation index becomes large, but most of the inclusions are SiO 2 -based, and it is not a preferable inclusion, so be careful. C
The addition amount a can be applied within the range of W ≧ 0.08 kg / Ton. From the above, the upper limit of the operation index I is I = 16
It can be used to some extent.
【０００６】[0006]
【作用】Ｃａ快削鋼のＣａ添加前のベース鋼はＳｉ−Ｍ
ｎ脱酸鋼であり、その介在物組成はＳｉＯ2−ＭｎＯ系
となっている。これらの介在物を低融点組成のアノーサ
イト；ＣａＯ・Ａｌ2Ｏ3・２ＳｉＯ2、あるいはゲーレ
ナイト；２ＣａＯ・Ａｌ2Ｏ3・ＳｉＯ2領域とするた
め、Ｃａ添加前の取鍋スラグのＣａＯ／ＳｉＯ2は約
１．０前後を目標とする。このことは、最終的な介在
物組成はスラグ−メタル間の熱力学的平衡の影響を受け
ること。また、スラグの溶鋼への懸濁を想定、取鍋スラ
グ組成は目標介在物組成に近似させることを意味する。
ＣａＯ／ＳｉＯ2を低めにすることは、熱力学的平衡
に従い、鋼中Ａｌを低位に保ち、鋼中へのＡｌインプッ
トの増加に伴う被削性に有害な硬質・非延性のＡｌ2Ｏ3
介在物の生成抑制効果をもたらすこと。また、同時に
平衡酸素量が上昇し、以降のＣａ添加におけるＣａＯ・
Ａｌ2Ｏ3・ＳｉＯ2系低融点介在物への形態制御を容易
にする作用をもたらす。一方、Ｃａ添加により低融点ア
ノーサイトあるいはゲーレナイト領域の介在物組成を得
るためには、既述の条件に加えてＣａ添加量が重要な要
因であり、介在物の形態制御はＣａ添加量とＣａを添加
する際のその他の条件との組合せにより目標とする組成
領域への制御が可能となる。[Function] The base steel before Ca addition of Ca free-cutting steel is Si-M
n deoxidized steel, the composition of inclusions of which is SiO 2 —MnO system. In order to make these inclusions the anorthite of low melting point composition; CaO.Al 2 O 3 .2SiO 2 or the grenite; 2CaO.Al 2 O 3 .SiO 2 region, CaO / SiO of the ladle slag before Ca addition 2 targets around 1.0. This means that the final inclusion composition is affected by the slag-metal thermodynamic equilibrium. In addition, assuming that the slag is suspended in molten steel, it means that the ladle slag composition approximates to the target inclusion composition.
Lowering CaO / SiO 2 keeps Al in steel at a low level in accordance with thermodynamic equilibrium, and hard and non-ductile Al 2 O 3 harmful to machinability with increase in Al input into steel.
To bring about the effect of suppressing the generation of inclusions. At the same time, the equilibrium oxygen amount increases, and CaO.
This brings about the effect of facilitating the morphology control of the Al 2 O 3 .SiO 2 -based low melting point inclusions. On the other hand, in order to obtain the composition of inclusions in the low-melting point anorthite or the grenite region by adding Ca, the Ca addition amount is an important factor in addition to the above-mentioned conditions. It becomes possible to control to the target composition region by combining with other conditions when adding.
【０００７】[0007]
【実施例】２７０Ｔ／ＣＨ転炉の出鋼時に溶鋼成分およ
び取鍋スラグ組成を調整した。Ｃａ添加前の溶鋼中の
Ｔ．Ａｌは０．００１％であり、取鍋内スラグの塩基度
は約１．０であった。その後Ｃａ添加はＣａ３１％−Ｓ
ｉ５６％組成のものをインジェクション法にて行った。
溶鋼は断面サイズ３５０×５６０ｍｍの曲げ型連続鋳造
機にて鋳造され、復熱炉経由で最終的には１６２×１６
２ｍｍのビレットにブレークダウンした。介在物形態の
調査は上記ビレットの対角線１／４長さ部からの切り出
しサンプルにより４００倍の顕微鏡にて行い、成分はＥ
ＰＭＡにて分析を行った。介在物形態の評価は顕微鏡観
察での介在物の長さｌと厚さｄの比；ｌ／ｄ（以下アス
ペクト比と定義）にて行った。表１に今回実炉試験を実
施した１０ヒートの溶鋼成分、スラグ成分、介在物組
成、およびアスペクト比を示す。ビレット介在物のアス
ペクト比は溶鋼へのＣａ添加原単位Ｗ〔ｋｇ／Ｔ−Ｓ〕
と取鍋スラグ塩基度Ｖ、すなわちＶ＝（％ＣａＯ）／
（％ＳｉＯ2）との組合せによる操業インデックスＩ、
すなわちＩ＝１／（Ｗ・Ｖ）と非常に大きな相関が認め
られる（図１）。すなわち、ビレット介在物のアスペク
ト比は操業インデックスＩを制御することによりコント
ロールが可能である。具体的には被削性の優れた延性介
在物を得るためには操業インデックスを大きくすると良
い。表２に図１の試験ヒートから３水準のアスペクト比
の介在物組成をＥＰＭＡで分析した結果を示す。さらに
表２の介在物組成をＣａＯ−Ａｌ2Ｏ3−ＳｉＯ2三元系
状態図上にプロットして図３に示す。これらの結果よ
り、アスペクト比の大きいＡおよびＢのヒートは被削性
の優れたアノーサイト、ゲーレナイト領域の介在物組成
となっている。Example: Molten steel composition and ladle slag composition were adjusted at the time of tapping in a 270T / CH converter. T. in molten steel before addition of Ca. Al was 0.001%, and the basicity of the slag in the ladle was about 1.0. After that Ca addition is Ca31% -S
The i56% composition was used by the injection method.
Molten steel is cast by a bending type continuous casting machine with a cross sectional size of 350 × 560 mm, and finally 162 × 16 through a recuperator.
Breaked down to a 2mm billet. The morphology of inclusions was examined by a 400 × microscope using a sample cut out from the diagonal 1/4 length portion of the billet, and the component was E
Analysis was performed by PMA. The morphology of inclusions was evaluated by the ratio of the length l and the thickness d of inclusions by microscope observation: l / d (hereinafter, referred to as aspect ratio). Table 1 shows the molten steel composition, slag composition, inclusion composition, and aspect ratio of 10 heats in which the actual furnace test was performed this time. The aspect ratio of the billet inclusions is the basic unit of Ca addition to molten steel W [kg / T-S]
And ladle slag basicity V, that is, V = (% CaO) /
Operation index I in combination with (% SiO 2 ),
That is, a very large correlation is recognized with I = 1 / (W · V) (FIG. 1). That is, the aspect ratio of the billet inclusion can be controlled by controlling the operation index I. Specifically, in order to obtain a ductile inclusion with excellent machinability, it is advisable to increase the operation index. Table 2 shows the results of EPMA analysis of the inclusion composition having three different aspect ratios from the test heat of FIG. Further shown in FIG. 3 by plotting the composition of inclusions in Table 2 in CaO-Al 2 O 3 -SiO 2 ternary phase diagram on. From these results, the heats of A and B having a large aspect ratio have the composition of inclusions in the anorthite and gehlenite regions, which have excellent machinability.
【０００８】[0008]
【表１Ｂ】 [Table 1B]
【０００９】[0009]
【表１Ｂ】 [Table 1B]
【００１０】[0010]
【表２】 [Table 2]
【００１１】[0011]
【発明の効果】本発明によれば、被削性の優れた低融点
で延性に優れた介在物組成を得ることができ、被削性に
悪影響を及ぼす硬質・非延性の介在物の生成を防止する
ことができるので、被削性の優れたＣａ快削鋼を安定し
て製造することができる。According to the present invention, it is possible to obtain an inclusion composition having a low melting point and excellent ductility, which is excellent in machinability, and to form hard and non-ductile inclusions which adversely affect machinability. Since it can be prevented, Ca free-cutting steel excellent in machinability can be stably manufactured.
【００１２】[0012]
【図１】Ｃａ添加の操業インデックスとビレット介在物
のアスペクト比を示す図表、FIG. 1 is a chart showing the operation index of Ca addition and the aspect ratio of billet inclusions,
【図２】Ｃａ脱酸鋼の鋼中Ｔ．Ａｌと介在物中Ａｌ2０3
濃度の関係を示す図表、FIG. 2 T. in steel of Ca deoxidized steel. Al and inclusions Al 2 0 3
Chart showing the relationship of concentration,
【図３】アスペクト比の３水準の介在物をＣａＯ−Ａｌ
2Ｏ3−ＳｉＯ2三元系状態図に示した図表である。FIG. 3: CaO-Al inclusions with three levels of aspect ratio
It is a chart shown in a 2 O 3 -SiO 2 ternary system phase diagram.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 大木 光一 北海道室蘭市仲町12番地 新日本製鐵株式 会社 室蘭製鐵所内 (72)発明者 柳瀬 雅人 北海道室蘭市仲町12番地 新日本製鐵株式 会社 室蘭製鐵所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Oki, 12 Nakamachi, Muroran, Muroran, Hokkaido Inside Nippon Steel Co., Ltd. Muroran Works (72) Inventor, Masato Yanase, 12 Nakamachi, Muroran, Hokkaido Muroran, Nippon Steel Co., Ltd. Inside the steelworks
Claims (1)
方法において、鋼浴中の全Ａｌ含有量を０．００２％以
下とし、次いでＣａを添加する際にこの溶鋼を保持する
溶鋼容器内のスラグ塩基度ＶおよびＣａの添加量Ｗによ
り下記（１）式で定められる操業インデックスＩを下記
（２）式の範囲に制御してＣａを添加することを特徴と
するＣａ快削鋼の溶製方法。 Ｉ＝１／Ｗ・Ｖ ・・・・・（１） ４≦Ｉ≦１６ ・・・・・（２） 但し、Ｗ：溶鋼中に添加するＣａまたはＣａ合金のＣａ
換算原単位（ｋｇ／Ｔｏｎ） Ｖ：スラグの塩基度 （％ＣａＯ）／（％ＳｉＯ2）1. A method for producing a Ca free-cutting steel in which Ca is added to molten steel, the total Al content in a steel bath is set to 0.002% or less, and the molten steel is held when the Ca is added next. Ca free-cutting steel characterized in that Ca is added by controlling the operation index I defined by the following formula (1) within the range of the following formula (2) by the slag basicity V in the container and the addition amount W of Ca. Method of melting. I = 1 / W · V (1) 4 ≦ I ≦ 16 (2) where W: Ca added to the molten steel or Ca of Ca alloy
Conversion intensity (kg / Ton) V: slag basicity (% CaO) / (% SiO 2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6368991A JPH0784612B2 (en) | 1991-03-06 | 1991-03-06 | Melting method of Ca free-cutting steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6368991A JPH0784612B2 (en) | 1991-03-06 | 1991-03-06 | Melting method of Ca free-cutting steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04280911A JPH04280911A (en) | 1992-10-06 |
| JPH0784612B2 true JPH0784612B2 (en) | 1995-09-13 |
Family
ID=13236599
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6368991A Expired - Lifetime JPH0784612B2 (en) | 1991-03-06 | 1991-03-06 | Melting method of Ca free-cutting steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0784612B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003293027A (en) * | 2002-04-09 | 2003-10-15 | Daido Steel Co Ltd | Manufacturing method of calcium free-cutting stainless steel |
| JP5137082B2 (en) * | 2008-12-19 | 2013-02-06 | 新日鐵住金株式会社 | Steel for machine structure and manufacturing method thereof |
-
1991
- 1991-03-06 JP JP6368991A patent/JPH0784612B2/en not_active Expired - Lifetime
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| Publication number | Publication date |
|---|---|
| JPH04280911A (en) | 1992-10-06 |
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