JPH09310113A - Refining method for highly clean stainless steel - Google Patents
Refining method for highly clean stainless steelInfo
- Publication number
- JPH09310113A JPH09310113A JP14855096A JP14855096A JPH09310113A JP H09310113 A JPH09310113 A JP H09310113A JP 14855096 A JP14855096 A JP 14855096A JP 14855096 A JP14855096 A JP 14855096A JP H09310113 A JPH09310113 A JP H09310113A
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- Prior art keywords
- inclusions
- refining
- molten steel
- stainless steel
- added
- 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.)
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- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ステンレス鋼の精
錬法において、Ｃａの添加方法およびスラグの組成を制
御することにより、溶鋼中の非金属介在物（以下、単に
介在物という）の無害化をはかる高清浄度ステンレス鋼
の製造方法に関するものである。TECHNICAL FIELD The present invention relates to the detoxification of non-metallic inclusions (hereinafter simply referred to as inclusions) in molten steel by controlling the addition method of Ca and the composition of slag in the refining method of stainless steel. The present invention relates to a method for producing high cleanliness stainless steel.
【０００２】[0002]
【従来の技術】ステンレス鋼の介在物は、その量が多す
ぎたり融点が高く硬質の場合には、製品の表面疵や加工
時の割れ発生の原因となる。一般に介在物を除去した
り、介在物の融点を下げ軟質化する方法はステンレス鋼
の精錬ではＡＯＤ，ＶＯＤ等の二次精錬炉で実施してい
る。2. Description of the Related Art If inclusions of stainless steel are too much or have a high melting point and are hard, they may cause surface defects of products or cracks during processing. Generally, the method of removing inclusions or lowering the melting point of inclusions to soften them is carried out in a secondary refining furnace such as AOD or VOD in refining stainless steel.
【０００３】すなわち、酸素ガスを吹込み、脱炭等の処
理を行う酸化精錬の終了後、酸化精錬時に生成したクロ
ム酸化物を含むスラグを還元するために、ＣａＯを主体
とする塩基性フラックスと共に、ＳｉやＡｌ等の還元剤
を添加し、Ａｒガスや窒素ガス等の不活性ガスを吹込む
ことにより攪拌し、脱酸および介在物の除去を促進させ
ている。特に低硫・低酸素化の要求される材料に対して
は還元剤としてＡｌを用いる方法が採用されている。That is, in order to reduce the slag containing chromium oxide produced during the oxidative refining after the completion of the oxidative refining in which oxygen gas is blown and treatment such as decarburization, a basic flux mainly composed of CaO is used. , Si, Al, etc. are added, and an inert gas such as Ar gas, nitrogen gas, etc. is blown in to stir to promote deoxidation and removal of inclusions. In particular, a method using Al as a reducing agent is adopted for a material that requires low sulfur and low oxygen content.
【０００４】これはＡｌは脱酸力が強く、脱硫能の高い
スラグを形成させることができるためである。また、こ
の方法では通常、還元時に生成した高融点のＡｌ2 Ｏ3
を改質して、介在物の組成を抑制し、かつ鋳造時のノズ
ル閉塞を防止するためにＣａが添加されている。This is because Al has a strong deoxidizing power and can form a slag having a high desulfurizing ability. In this method, the high melting point Al 2 O 3 produced during reduction is usually used.
Is added to suppress the composition of inclusions and prevent nozzle clogging during casting.
【０００５】ステンレス鋼中の介在物の低減および軟質
化をはかるためにＣａやＡｌを添加する例としては、特
公昭６０−３０６８６号公報および特開平６０−３０６
４３９号公報に記載の方法が知られている。特公昭６０
−３２６８６号公報に記載の方法は、酸素濃度に対応し
てＣａまたはＡｌの添加量を制御することにより、介在
物を低融点のＣａＯ−Ａｌ2 Ｏ3 とすることで、浮上分
離を促進させて大型介在物量を低減できることが述べら
れている。しかし、該方法では硬質の介在物（ＭｇＯ−
Ａｌ2 Ｏ3 ，ＭｇＯ）が皆無になっておらず、介在物の
無害化の点では問題が残っている。As an example of adding Ca or Al in order to reduce inclusions and soften stainless steel, Japanese Patent Publication No. 60-30686 and Japanese Patent Laid-Open No. 60-306 are known.
The method described in Japanese Patent No. 439 is known. Japanese Patent Sho 60
The method described in JP-A-32686 promotes levitation separation by controlling the addition amount of Ca or Al in accordance with the oxygen concentration and by using CaO-Al 2 O 3 having a low melting point as an inclusion. It is described that the amount of large inclusions can be reduced. However, in this method, hard inclusions (MgO-
Al 2 O 3 , MgO) is not completely eliminated, and a problem remains in terms of detoxifying inclusions.
【０００６】さらに、特開平６−３０６４３９号公報に
記載の方法は、Ａｌ中の〔Ｍｇ〕濃度を１．０ｍａｓｓ
％以下とし、スラグ中の（ＭｇＯ）濃度を８ｍａｓｓ％
以下とし、かつ〔Ｃａ〕と〔Ａｌ〕濃度を調整すること
で硬質のＭｇＯ−Ａｌ2 Ｏ3介在物を低減できることが
述べられている。しかし、この方法ではＡｌ2 Ｏ3 濃度
の高い高融点のＣａＯ−Ａｌ2 Ｏ3 介在物（一般には６
０ｍａｓｓ％以上のＡｌ2 Ｏ3 を含む）およびＭｇＯ介
在物が残存しており、一部にはＭｇＯ−Ａｌ2 Ｏ3 介在
物が存在するために介在物の無害化は完全に達成されて
いない。Further, according to the method described in JP-A-6-306439, the [Mg] concentration in Al is 1.0 mass.
% Or less, and the (MgO) concentration in the slag is 8 mass%
It is stated to be reduced to MgO-Al 2 O 3 inclusions rigid by adjusting the following and then, and the [Ca] [Al] concentration. However, according to this method, CaO—Al 2 O 3 inclusions having a high melting point and high Al 2 O 3 concentration (generally 6
The inclusion of 0 mass% or more of Al 2 O 3 ) and MgO inclusions remain, and the inclusion of MgO-Al 2 O 3 inclusions is partially present, so that detoxification of inclusions is not completely achieved. .
【０００７】[0007]
【発明が解決しようとする課題】本発明はステンレス鋼
の精錬法において、還元剤にＡｌを用い、その後に添加
するＣａ量、Ｃａ添加後の不活性ガス吹込み量およびス
ラグ組成を制御することにより、還元時に生成した硬質
のＡｌ2 Ｏ3 を軟質化し、かつ硬質の介在物の生成を抑
えることで、介在物の完全無害化を達成し、これにより
製品の表面疵や加工時の割れを防止することを目的とす
るものである。DISCLOSURE OF THE INVENTION According to the present invention, in a refining method for stainless steel, Al is used as a reducing agent, and the amount of Ca added thereafter, the amount of inert gas blown after the addition of Ca, and the slag composition are controlled. This softens the hard Al 2 O 3 generated during reduction and suppresses the formation of hard inclusions to achieve complete harmless inclusions, which results in product surface defects and cracks during processing. The purpose is to prevent.
【０００８】[0008]
【課題を解決するための手段】本発明は、上記目的を達
成するために下記手段を採用するものである。すなわ
ち、ステンレス鋼の精錬において、酸化精錬時に生成し
たクロム酸化物を含むスラグの還元剤としてＡｌを用
い、かつ出鋼後の取鍋内の溶鋼にＣａまたはＣａ合金あ
るいはこれらの両者を添加する工程において、Ｃａまた
はＣａ合金あるいはこれらの両者を添加する量をＣａの
純分で溶鋼トン当り５０ｇ以上とし、かつ該Ｃａの添加
後に溶鋼内に下記（１）式を満足する量の不活性ガスを
吹込んで溶鋼の攪拌を行うことを特徴とするステンレス
鋼の高清浄化精錬法にある。 Ｑd ≧ＷCa／４．２ ・・・（１） Ｑd ：不活性ガスの吹込み流量（Ｎｍ3 ） ＷCa：添加したＣａまたはＣａ合金中のＣａ純分量の合
計（ｋｇ）The present invention employs the following means in order to achieve the above object. That is, in the refining of stainless steel, a step of using Al as a reducing agent for slag containing chromium oxide produced during oxidation refining and adding Ca or Ca alloy or both to molten steel in a ladle after tapping. In the above, the amount of Ca or Ca alloy or both of them added as pure Ca is 50 g or more per ton of molten steel, and after the addition of Ca, an amount of an inert gas satisfying the following formula (1) is added in the molten steel. It is a highly purified refining method for stainless steel, which is characterized in that the molten steel is agitated by blowing. Q d ≧ W Ca /4.2 (1) Q d : Blow-off flow of inert gas (Nm 3 ) W Ca : Total amount of pure Ca in the added Ca or Ca alloy (kg)
【０００９】さらに、前記精錬後のスラグ中の（Ｍｇ
Ｏ）濃度を１５ｍａｓｓ％以下とし、かつスラグ中の
（ＣａＯ）／（Ａｌ2 Ｏ3 ）の濃度比を１．０以上、
２．５以下とすることを特徴とするステンレス鋼の高清
浄化精錬法にある。Further, the (Mg
O) concentration is 15 mass% or less, and the (CaO) / (Al 2 O 3 ) concentration ratio in the slag is 1.0 or more,
It is a highly purified refining method for stainless steel, which is characterized in that it is 2.5 or less.
【００１０】[0010]
【発明の実施の形態】本発明者らはステンレス鋼の製品
の表面疵や加工時の割れの原因として、硬質の介在物で
あるＡｌ2 Ｏ3 ，ＭｇＯ，ＭｇＯ−Ａｌ2 Ｏ3 ，ＣａＯ
およびＡｌ2Ｏ3 濃度の高いＣａＯ−Ａｌ2 Ｏ3 の影響
が極めて大きいことを見出し、かつこれらの介在物の硬
質、軟質の区別は介在物組成より求められる介在物の融
点で評価できることを見出した。さらに、Ａｌを還元剤
として用い、精錬炉から出鋼後、取鍋内でＣａまたはＣ
ａ合金あるいはこれらの両者を添加した場合の介在物の
組成推移について種々の調査を重ねた結果、下記の知見
を得た。DETAILED DESCRIPTION OF THE INVENTION The present inventors have as a surface flaw or cause cracking during processing of products of stainless steel, Al 2 O 3 is a inclusions hard, MgO, MgO-Al 2 O 3, CaO
Heading and Al 2 O 3 found that higher effects of CaO-Al 2 O 3 concentrations is very large, and hard these inclusions, that distinction between soft can be evaluated at the melting point of the inclusions obtained from the composition of inclusions It was Furthermore, using Al as a reducing agent, after tapping from the refining furnace, Ca or C in the ladle
As a result of various investigations on the transition of the composition of inclusions when alloy a or both of them were added, the following findings were obtained.
【００１１】還元剤としてＡｌを添加した場合は、溶
鋼中に介在物として硬質のＡｌ2 Ｏ3 ，ＭｇＯ−Ａｌ2
Ｏ3 ，ＭｇＯおよびＡｌ2 Ｏ3 濃度の高いＣａＯ−Ａｌ
2 Ｏ3 が生成し、これが後工程まで残存することがあ
る。 取鍋内で、ＣａまたはＣａ合金あるいはこれらの両者
を添加し、溶鋼の攪拌を十分に行うことによって、上記
介在物の軟質化反応が進行し、介在物の主体は一部にＳ
ｉＯ2 およびＭｇＯを含んだ比較的Ａｌ2 Ｏ3 濃度の低
いＣａＯ−Ａｌ2 Ｏ3 となる。When Al is added as a reducing agent, hard Al 2 O 3 and MgO-Al 2 are contained as inclusions in the molten steel.
O 3, MgO and Al 2 O 3 higher concentrations CaO-Al
2 O 3 may be generated and remain in the subsequent steps. By adding Ca or Ca alloy or both of them in a ladle and stirring the molten steel sufficiently, the softening reaction of the inclusions proceeds, and the inclusions mainly contain S.
including iO 2 and MgO become relatively the concentration of Al 2 O 3 low CaO-Al 2 O 3.
【００１２】ＣａまたはＣａ合金あるいはこれらの両
者を添加した後の溶鋼の攪拌が不十分な場合には、硬質
のＡｌ2 Ｏ3 ，ＭｇＯ−Ａｌ2 Ｏ3 ，ＭｇＯおよびＡｌ
2 Ｏ3 濃度の高いＣａＯ−Ａｌ2 Ｏ3 が残存すると共
に、Ｃａ添加によって生成したＣａＯが介在物として残
存することがある。 スラグ中の（ＭｇＯ）濃度が極端に高い場合およびス
ラグ中の（ＣａＯ）／（Ａｌ2 Ｏ3 ）濃度比が極端に高
かったり、低かったりした場合には、上記の硬質の介在
物が残存することがある。When the molten steel is not sufficiently stirred after adding Ca or Ca alloy or both of them, hard Al 2 O 3 , MgO-Al 2 O 3 , MgO and Al.
With 2 O 3 concentrations of high CaO-Al 2 O 3 remains, CaO produced by Ca addition may remain as inclusions. If the (MgO) concentration in the slag is extremely high, or if the (CaO) / (Al 2 O 3 ) concentration ratio in the slag is extremely high or low, the above hard inclusions remain. Sometimes.
【００１３】したがって、硬質の介在物であるＡｌ2 Ｏ
3 ，ＭｇＯ−Ａｌ2 Ｏ3 ，ＭｇＯ，ＣａＯおよびＡｌ2
Ｏ3 濃度の高いＣａＯ−Ａｌ2 Ｏ3 の生成を抑制するに
は、Ｃａの添加量、Ｃａ添加後の不活性ガス吹込みによ
る溶鋼の攪拌量およびスラグの組成を適切に制御するこ
とが非常に重要であることがわかった。また、前記の特
開平６−３０６４３９号公報に記載されている、還元剤
として添加するＡｌ中のＭｇ濃度の規制、あるいは溶鋼
中〔Ｃａ〕，〔Ａｌ〕の規制は、Ｃａ添加後の溶鋼への
不活性ガス吹込み量が十分であれば緩和できることを確
認した。Therefore, the hard inclusions Al 2 O
3, MgO-Al 2 O 3 , MgO, CaO and Al 2
In order to suppress the formation of CaO-Al 2 O 3 having a high O 3 concentration, it is extremely necessary to appropriately control the amount of Ca added, the amount of molten steel stirred by the inert gas blowing after the addition of Ca, and the composition of the slag. Turned out to be important. Further, the regulation of the Mg concentration in Al added as a reducing agent, or the regulation of [Ca] and [Al] in molten steel, which is described in the above-mentioned JP-A-6-306439, refers to the molten steel after Ca addition. It was confirmed that it could be relaxed if the amount of the inert gas blown was sufficient.
【００１４】さらに、介在物には多種類の硬質の介在物
が存在することから、これらを一律に評価する指標とし
て、介在物の組成より求められる介在物の融点を用いる
ことが有効であり、介在物の融点が１６００℃を超える
介在物を高融点介在物とし、この高融点介在物の全介在
物に占める存在率を高融点介在物の発生率として定義し
て、介在物の無害化を評価すればよいことがわかった。
なお、高融点介在物の発生率が高いほど、介在物の絶対
量が多くなる傾向になることが確認された。Further, since there are many kinds of hard inclusions in the inclusions, it is effective to use the melting point of the inclusions determined from the composition of the inclusions as an index for uniformly evaluating these inclusions. Inclusions having a melting point of more than 1600 ° C. are defined as high melting point inclusions, and the existence ratio of the high melting point inclusions in all the inclusions is defined as the generation rate of the high melting point inclusions to make the inclusions harmless. It turns out that it should be evaluated.
It was confirmed that the higher the generation rate of high melting point inclusions, the greater the absolute amount of inclusions.
【００１５】上記の結果に基づき、Ｃａ添加量、Ｃａ添
加後の溶鋼への不活性ガス吹込み量およびスラグ組成を
制御することに着目して、高融点介在物の発生率を抑え
る条件について検討した。なお、還元剤としてＡｌを用
いる場合、スラグの還元反応の促進をはかり、かつ低硫
・低酸素化を円滑に達成するためには、精錬中における
溶鋼中の〔Ａｌ〕濃度は１００〜１５００ｐｐｍの範囲
であり、本発明においてもこの範囲内に調整している。Based on the above results, focusing on controlling the amount of Ca added, the amount of inert gas blown into the molten steel after addition of Ca, and the slag composition, the conditions for suppressing the occurrence rate of high melting point inclusions were examined. did. When Al is used as the reducing agent, the [Al] concentration in the molten steel during refining is 100 to 1500 ppm in order to promote the reduction reaction of slag and to achieve low sulfur and low oxygen smoothly. This is the range, and the range is adjusted within this range also in the present invention.
【００１６】図１は、酸化精錬後のステンレス鋼にＡｌ
を添加して還元精錬を行い、この溶鋼を取鍋に出鋼し、
取鍋内にＣａあるいはＣａ合金を添加し、不活性ガスを
吹込んで精錬を行った場合の、取鍋で添加する溶鋼トン
当りのＣａ添加量と高融点介在物の発生率の関係を示
す。なお、Ｃａ源としてＣａ合金を添加する場合のＣａ
添加量はＣａ合金中に含まれるＣａ量であり、Ｃａ添加
量／ガス吹込み流量は４．０ｋｇ／Ｎｍ3 以下とした。
図１より、溶鋼トン当りのＣａ添加量が５０ｇより小さ
い場合には、ＭｇＯ，ＭｇＯ−Ａｌ2 Ｏ3 およびＡｌ2
Ｏ3 濃度の高いＣａＯ−Ａｌ2 Ｏ3 の高融点介在物の発
生率が急激に増大するために、溶鋼トン当りのＣａ添加
量は５０ｇ以上が必要である。FIG. 1 shows that stainless steel after oxidation refining is Al
Is added to carry out reduction refining, and this molten steel is tapped in a ladle,
The relationship between the amount of Ca added per ton of molten steel added in the ladle and the generation rate of high melting point inclusions when Ca or a Ca alloy is added to the ladle and refining is performed by blowing an inert gas is shown. In addition, Ca when adding a Ca alloy as a Ca source
The addition amount is the amount of Ca contained in the Ca alloy, and the Ca addition amount / gas injection flow rate was 4.0 kg / Nm 3 or less.
From FIG. 1, when the amount of Ca added per ton of molten steel is less than 50 g, MgO, MgO-Al 2 O 3 and Al 2
For the incidence of O 3 concentration high CaO-Al refractory inclusions 2 O 3 increases rapidly, Ca addition amount per ton of the molten steel is required than 50 g.
【００１７】図２は、図１と同様な精錬において、Ｃａ
添加量／ガス吹込み流量を１．３〜８．２ｋｇ／Ｎｍ3
とした場合のＣａ添加量／ガス吹込み流量と高融点介在
物の発生率の関係を示す。なお、Ｃａの溶鋼トン当りの
添加量は、いずれも５０ｇ以上とした場合の値である。
図２より、Ｃａ添加量／ガス吹込み流量の値が４．２を
超えると高融点介在物の発生率が急激に増大するため
に、Ｃａ添加量／ガス吹込み流量は４．２以下とする必
要がある。FIG. 2 shows Ca in the same refining process as in FIG.
Addition amount / gas injection flow rate is 1.3 to 8.2 kg / Nm 3
The relationship between the Ca addition amount / gas injection flow rate and the generation rate of high-melting point inclusions is shown below. The addition amount of Ca per ton of molten steel is a value when the amount is 50 g or more.
From FIG. 2, when the value of Ca addition amount / gas blowing flow rate exceeds 4.2, the generation rate of high-melting point inclusions rapidly increases, so the Ca addition amount / gas blowing flow rate is 4.2 or less. There is a need to.
【００１８】これより、前記（１）式の関係が求められ
る。なお、Ｃａ添加量およびガス吹込み流量が多くなる
と、取鍋での溶鋼温度の低下が大きく、制御が難しくな
るために、溶鋼トン当りのＣａ添加量としては１２０ｇ
以下、Ｃａ添加量／ガス吹込み流量の比は１．５ｋｇ／
Ｎｍ3 以上が望ましい。From this, the relation of the equation (1) is obtained. When the Ca addition amount and the gas injection flow rate are large, the molten steel temperature in the ladle is largely decreased and it is difficult to control. Therefore, the Ca addition amount per ton of molten steel is 120 g.
Below, the ratio of Ca addition amount / gas injection flow rate is 1.5 kg /
Nm 3 or more is desirable.
【００１９】図３には前記精錬後のスラグ中の（Ｍｇ
Ｏ）濃度と高融点介在物の発生率の関係を示す。なお、
Ｃａの添加量およびＣａ添加後の溶鋼への不活性ガス吹
込み流量は本発明の条件内で行った場合である。図３よ
り、スラグ中の（ＭｇＯ）濃度が１５ｍａｓｓ％を超え
ると徐々に高融点介在物の発生率が増大しており、スラ
グ中の（ＭｇＯ）濃度は１５ｍａｓｓ％以下とする必要
がある。FIG. 3 shows (Mg in the slag after the refining).
The relationship between O) concentration and the generation rate of high melting point inclusions is shown. In addition,
The amount of Ca added and the flow rate of the inert gas blown into the molten steel after the addition of Ca are based on the conditions of the present invention. From FIG. 3, when the (MgO) concentration in the slag exceeds 15 mass%, the generation rate of high-melting point inclusions gradually increases, and the (MgO) concentration in the slag needs to be 15 mass% or less.
【００２０】図４には前記精錬後のスラグ中の（Ｃａ
Ｏ）／（Ａｌ2 Ｏ3 ）の濃度比と高融点介在物の発生率
の関係を示す。なお、Ｃａの添加量およびＣａ添加後の
溶鋼への不活性ガス吹込み流量は本発明の条件内で行っ
た場合である。図４より、スラグ中の（ＣａＯ）／（Ａ
ｌ2 Ｏ3 ）の濃度比が１．０未満および２．５を超える
と高融点介在物の発生率が増大しており、スラグ中の
（ＣａＯ）／（Ａｌ2 Ｏ3 ）の濃度比は１．０以上、
２．５以下にする必要がある。FIG. 4 shows (Ca) in the slag after the refining.
The relationship between the concentration ratio of (O) / (Al 2 O 3 ) and the generation rate of high melting point inclusions is shown. The amount of Ca added and the flow rate of the inert gas blown into the molten steel after the addition of Ca are based on the conditions of the present invention. From Fig. 4, (CaO) / (A in the slag
When the concentration ratio of l 2 O 3 ) is less than 1.0 and exceeds 2.5, the generation rate of high-melting point inclusions increases, and the concentration ratio of (CaO) / (Al 2 O 3 ) in the slag is 1.0 or more,
It should be 2.5 or less.
【００２１】以上のように、Ａｌ2 Ｏ3 ，ＭｇＯ，Ｍｇ
Ｏ−Ａｌ2 Ｏ3 ，ＣａＯおよびＡｌ 2 Ｏ3 濃度の高いＣ
ａＯ−Ａｌ2 Ｏ3 の高融点介在物の発生率を抑制するた
めには、取鍋内で添加するＣａ量、Ｃａの添加後の溶鋼
内への不活性ガスの吹込み流量および精錬後のスラグ中
の（ＭｇＯ）濃度、（ＣａＯ）／（Ａｌ2 Ｏ3 ）濃度比
を適正な範囲に制御することが重要である。As described above, AlTwo OThree , MgO, Mg
O-AlTwo OThree , CaO and Al Two OThree High concentration C
aO-AlTwo OThree To suppress the generation rate of high melting point inclusions
To add, the amount of Ca added in the ladle and the molten steel after the addition of Ca
Inflow rate of inert gas into slag and slag after refining
(MgO) concentration of (CaO) / (AlTwo OThree ) Concentration ratio
Is important to control within a proper range.
【００２２】[0022]
【実施例】ＳＵＳ３０４ステンレス鋼（１８ｍａｓｓ％
Ｃｒ−８ｍａｓｓ％Ｎｉ）を６０ｔ電気炉にて溶解し、
ＡＯＤ炉にてＯ2 −Ａｒ混合ガスによる脱炭精錬を行っ
た後に、Ａｒガス吹込み下で還元剤としてＡｌを添加し
て、還元精錬を行った後に取鍋に出鋼した。取鍋内では
ＣａおよびＣａ合金を添加し、その後、取鍋底部よりＡ
ｒガスを吹込み攪拌処理を行った。なお、精錬中におけ
る溶鋼中の〔Ａｌ〕濃度は１００〜１０００ｐｐｍの範
囲にあり、スラグ量は溶鋼トン当り４０〜１００ｋｇの
範囲にあった。[Example] SUS304 stainless steel (18 mass%
Cr-8 mass% Ni) is melted in a 60t electric furnace,
After decarburizing and refining with an O 2 -Ar mixed gas in an AOD furnace, Al was added as a reducing agent under Ar gas blowing, and after reducing and refining, steel was tapped in a ladle. Add Ca and Ca alloy in the ladle, and then add A from the bottom of the ladle.
R gas was blown in to carry out a stirring process. The [Al] concentration in the molten steel during refining was in the range of 100 to 1000 ppm, and the amount of slag was in the range of 40 to 100 kg per ton of molten steel.
【００２３】得られた鋼は連続鋳造により、断面サイズ
１７８ｍｍφのビレットとし、次いで線材圧延により
５．５ｍｍφの線材とし、この線材を０．５ｍｍφに冷
間伸線加工した。表１にＡＯＤ精錬後のスラグ組成、Ｃ
ａ添加条件および線材品質をまとめて示す。なお、Ｎ
ｏ．１〜６の例は本発明例、Ｎｏ．７〜１０は本発明の
条件外の比較例を示す。The obtained steel was continuously cast into a billet having a cross-sectional size of 178 mmφ and then rolled into a wire rod having a diameter of 5.5 mmφ. The wire rod was cold-drawn into 0.5 mmφ. Table 1 shows the slag composition after AOD refining, C
a Addition conditions and wire rod quality are shown together. Note that N
o. Examples of Nos. 1 to 6 are the present invention, No. 7 to 10 show comparative examples outside the conditions of the present invention.
【００２４】[0024]
【表１】 [Table 1]
【００２５】介在物の調査は、線材横断面１０ｃｍ2 を
光学顕微鏡により観察し、５μｍ以上の介在物個数を測
定すると共に、Ｘ線マイクロアナライザーによる組成分
析を行った。組成分析結果より各介在物毎の融点を換算
し、融点が１６００℃以上の介在物個数を求め、高融点
介在物の発生率を算出した。The inclusions were examined by observing a cross section of 10 cm 2 of the wire with an optical microscope, measuring the number of inclusions having a size of 5 μm or more, and analyzing the composition with an X-ray microanalyzer. The melting point of each inclusion was converted from the composition analysis result, the number of inclusions having a melting point of 1600 ° C. or higher was determined, and the incidence of high-melting inclusions was calculated.
【００２６】本発明の例では高融点介在物の発生率が低
位に安定しており、かつ線材中の５μｍ以上の介在物個
数も著しく低減しており、介在物の無害化を達成でき
た。In the example of the present invention, the generation rate of inclusions having a high melting point was stable at a low level, and the number of inclusions having a size of 5 μm or more in the wire was remarkably reduced, so that the inclusions could be rendered harmless.
【００２７】[0027]
【発明の効果】本発明では、ステンレス鋼の精錬におい
て、精錬後のスラグ組成、取鍋内で添加するＣａの量お
よびＣａ添加後の不活性ガスの吹込み流量を制御するこ
とにより、硬質の高融点介在物の発生率を低位に安定さ
せることができるので、介在物の無害化を達成できる。
このため、製品の表面疵や加工時の割れのない材料を製
造でき、冷間加工性の優れた細線、極細線などの製造が
可能になった。INDUSTRIAL APPLICABILITY In the present invention, in the refining of stainless steel, the slag composition after refining, the amount of Ca added in the ladle, and the flow rate of the inert gas after Ca addition are controlled to obtain a hard Since the generation rate of the high melting point inclusions can be stabilized at a low level, the inclusions can be rendered harmless.
As a result, it is possible to manufacture a material that does not have surface defects or cracks during processing, and it has become possible to manufacture fine wires and ultrafine wires with excellent cold workability.
【図１】取鍋内で添加するＣａまたはＣａ合金あるいは
これらの両者の溶鋼トン当りのＣａ添加量と高融点介在
物の発生率の関係を示す図FIG. 1 is a diagram showing the relationship between the amount of Ca added per ton of molten steel and the incidence of high melting point inclusions of Ca or Ca alloys or both of them added in a ladle.
【図２】取鍋内で添加するＣａ量とＣａ添加後の不活性
ガスの吹込み流量の比と高融点介在物の発生率の関係を
示す図FIG. 2 is a graph showing the relationship between the ratio of the amount of Ca added in the ladle to the flow rate of the inert gas after Ca addition and the incidence of high-melting-point inclusions.
【図３】精錬後のスラグ中の（ＭｇＯ）濃度と高融点介
在物の発生率の関係を示す図FIG. 3 is a diagram showing the relationship between the (MgO) concentration in the slag after refining and the generation rate of high melting point inclusions.
【図４】精錬後のスラグ中の（ＣａＯ）／（Ａｌ2 Ｏ
3 ）の濃度比と高融点介在物の発生率の関係を示す図FIG. 4 (CaO) / (Al 2 O in slag after refining
Diagram showing the relationship between the concentration ratio of 3 ) and the generation rate of high melting point inclusions
───────────────────────────────────────────────────── フロントページの続き (72)発明者 岩崎 央 山口県光市大字島田3434番地 新日本製鐵 株式会社光製鐵所内 (72)発明者 河合 浩之 山口県光市大字島田3434番地 新日本製鐵 株式会社光製鐵所内 (72)発明者 松並 忠則 山口県光市大字島田3434番地 新日本製鐵 株式会社光製鐵所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Hiroshi Iwasaki, 3434 Shimada, Hikari City, Yamaguchi Prefecture, Nippon Steel Works, Ltd. (72) Inventor Tadanori Matsunami 3434 Shimada, Hikari City, Yamaguchi Prefecture Shin Nippon Steel Co., Ltd. Hikari Steel Co., Ltd.
Claims (2)
時に生成したクロム酸化物を含むスラグの還元剤として
Ａｌを用い、かつ出鋼後の取鍋内の溶鋼にＣａまたはＣ
ａ合金あるいはこれらの両者を添加する工程において、
ＣａまたはＣａ合金あるいはこれらの両者を添加する量
をＣａの純分で溶鋼トン当り５０ｇ以上とし、かつ該Ｃ
ａの添加後に溶鋼内に下記（１）式を満足する量の不活
性ガスを吹込んで溶鋼の攪拌を行うことを特徴とするス
テンレス鋼の高清浄化精錬法。 Ｑd ≧ＷCa／４．２ ・・・（１） Ｑd ：不活性ガスの吹込み流量（Ｎｍ3 ） ＷCa：添加したＣａまたはＣａ合金中のＣａ純分量の合
計（ｋｇ）1. In the refining of stainless steel, Al is used as a reducing agent for slag containing chromium oxide produced during oxidation refining, and Ca or C is used as molten steel in a ladle after tapping.
In the process of adding a alloy or both of them,
The amount of Ca or Ca alloy or both of them added is 50 g or more per ton of molten steel in the pure content of Ca, and
A method for highly cleaning and refining stainless steel, characterized in that after the addition of a, an amount of an inert gas satisfying the following formula (1) is blown into the molten steel to stir the molten steel. Q d ≧ W Ca /4.2 (1) Q d : Blow-off flow of inert gas (Nm 3 ) W Ca : Total amount of pure Ca in the added Ca or Ca alloy (kg)
を１５ｍａｓｓ％以下とし、かつスラグの中の（Ｃａ
Ｏ）／（Ａｌ2 Ｏ3 ）の濃度比を１．０以上、２．５以
下とすることを特徴とする請求項１に記載のステンレス
鋼の高清浄化精錬法。2. The (MgO) concentration in the slag after refining is set to 15 mass% or less, and (Ca
The method for highly cleaning and refining stainless steel according to claim 1, wherein the concentration ratio of (O) / (Al 2 O 3 ) is 1.0 or more and 2.5 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14855096A JP4111352B2 (en) | 1996-05-21 | 1996-05-21 | High-cleaning refining method for stainless steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14855096A JP4111352B2 (en) | 1996-05-21 | 1996-05-21 | High-cleaning refining method for stainless steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09310113A true JPH09310113A (en) | 1997-12-02 |
| JP4111352B2 JP4111352B2 (en) | 2008-07-02 |
Family
ID=15455275
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14855096A Expired - Lifetime JP4111352B2 (en) | 1996-05-21 | 1996-05-21 | High-cleaning refining method for stainless steel |
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| Country | Link |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6353003B1 (en) | 1998-06-17 | 2002-03-05 | Eli Lilly And Company | Method for reducing levels of homocysteine and C-reactive protein |
| US6407243B1 (en) | 1994-09-20 | 2002-06-18 | Eli Lilly And Company | Benzofuran compounds, compositions, and methods |
| US6417198B1 (en) | 1993-12-21 | 2002-07-09 | Eli Lilly And Company | Methods of inhibiting CNS problems in post-menopausal women |
| US6436958B1 (en) | 1993-12-21 | 2002-08-20 | Eli Lilly And Company | Methods of inhibiting autoimmune diseases |
| US6440958B1 (en) | 1995-06-26 | 2002-08-27 | Eli Lilly And Company | Acrylic and propionic acid compounds, intermediates, processes, compositions, and methods |
| US6489355B2 (en) | 1993-12-01 | 2002-12-03 | Eli Lilly And Company | Methods of inhibiting the effects of amyloidogenic proteins |
-
1996
- 1996-05-21 JP JP14855096A patent/JP4111352B2/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6489355B2 (en) | 1993-12-01 | 2002-12-03 | Eli Lilly And Company | Methods of inhibiting the effects of amyloidogenic proteins |
| US6417198B1 (en) | 1993-12-21 | 2002-07-09 | Eli Lilly And Company | Methods of inhibiting CNS problems in post-menopausal women |
| US6436958B1 (en) | 1993-12-21 | 2002-08-20 | Eli Lilly And Company | Methods of inhibiting autoimmune diseases |
| US6407243B1 (en) | 1994-09-20 | 2002-06-18 | Eli Lilly And Company | Benzofuran compounds, compositions, and methods |
| US6440958B1 (en) | 1995-06-26 | 2002-08-27 | Eli Lilly And Company | Acrylic and propionic acid compounds, intermediates, processes, compositions, and methods |
| US6353003B1 (en) | 1998-06-17 | 2002-03-05 | Eli Lilly And Company | Method for reducing levels of homocysteine and C-reactive protein |
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| Publication number | Publication date |
|---|---|
| JP4111352B2 (en) | 2008-07-02 |
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