JP3893769B2 - Method for refining high Al content stainless steel - Google Patents
Method for refining high Al content stainless steel Download PDFInfo
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- JP3893769B2 JP3893769B2 JP27810698A JP27810698A JP3893769B2 JP 3893769 B2 JP3893769 B2 JP 3893769B2 JP 27810698 A JP27810698 A JP 27810698A JP 27810698 A JP27810698 A JP 27810698A JP 3893769 B2 JP3893769 B2 JP 3893769B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description
【０００１】
【発明の属する技術分野】
本発明はステンレス鋼の精錬方法に係り、とくにAlを１〜10wt％含有する高Al含有ステンレス鋼の２次精錬方法に関する。
【０００２】
【従来の技術】
ステンレス鋼は、従来から、転炉、電気炉で１次精錬されたのち、AOD 、VOD 等の２次精錬設備で、脱炭処理、脱酸・還元処理からなる２次精錬を施されて溶製されている。従来、Alを１〜10wt％含有する高Al含有ステンレス鋼の２次精錬は、Al2O3 耐火物を用いた取鍋（精錬容器）で行われてきた。例えば、特開平3-158410号公報には、3.0 重量％以上を含有する高Al含有ステンレス鋼の精錬において、鋼中のMg濃度を低下するために、鋼中Alを調整する際にスラグのCaO/Al2O3 を0.8 〜1.2 に調整し、かつスラグ中のSiO2＋MgO ＋MnO を５重量％以下に調整するフェライト系ステンレス鋼の製造方法が提案され、スラグ中のSiO2＋MgO ＋MnO を５重量％以下とする方法として、精錬容器内張りレンガ材質をAl2O3 を95重量％以上とすることが開示されている。
【０００３】
しかし、Al2O3 耐火物を用いた取鍋（精錬容器）は、特殊鍋であるためチャンスフリーで溶製することができないうえ、高価であるため、コストアップの原因となっていた。
【０００４】
【発明が解決しようとする課題】
一方、Al2O3 耐火物を用いた取鍋（精錬容器）に代えて、安価なMgO 含有耐火物を用いた取鍋（精錬容器）を用いて精錬した場合には、取鍋（精錬容器）の耐火物からMgO が溶出し、スラグ中のMgO 濃度が高くなる。MgO 濃度の高いスラグの存在下で、多量のAl（例えば、10〜120kg/t-steel ）を一括して投入すると、添加直後、スラグ近傍の高濃度Al領域において、スラグ中のMgO とAlが反応し、Mg蒸気を発生させるため、そのMg蒸気が大気中で酸化されることにより発火するという問題があった。そのために、MgO 含有耐火物を用いた取鍋（精錬容器）で高Al含有ステンレス鋼を溶製する場合には、Alは少量ずつ分割して添加することが要請され、そのため処理時間が大幅に延長し、コッストアップの一つの要因となっていた。
【０００５】
本発明は、上記した従来技術の問題に鑑み、安価なMgO 含有耐火物を用いた精錬容器を用いて安全でかつ短時間に、Alが１〜10wt％含有する高Al含有ステンレス鋼を２次精錬できる高Al含有ステンレス鋼の精錬方法を提案することを目的とする。
【０００６】
【課題を解決するための手段】
本発明者らは、上記課題を達成するため、鋭意研究した結果、Mg蒸気の発生を抑制するには、スラグ中MgO 濃度の最も低い時期にAlを添加することが重要であることに思い至った。従来の高Al含有ステンレス鋼のVOD 処理では、図３に示すように、まず酸素ガスを上吹きし溶鋼を脱炭する脱炭処理期と、その後、酸素吹精を止め、高真空下で還元剤（Fe-Si ）を添加しArガスを底吹きし溶鋼とスラグを攪拌しながら、溶湯の脱酸、スラグ中Crの還元等を行う脱酸・還元処理期からなる。
【０００７】
そこで、まず、含MgO 耐火物を用いた取鍋でAlキルドステンレス鋼をVOD 処理した際の、スラグ中MgO 濃度の変化を調査した。その結果を図１に示す。
図１から、脱炭処理期には、スラグ中MgO 濃度は低位に推移し、耐火物からのMgO の溶出は全く無いことがわかる。その後、還元剤を添加してスラグおよび溶湯を底吹きガスにより撹拌する脱酸・還元処理期には、スラグ中MgO 濃度が急激に増加しており、この時期に耐火物からのMgO の溶出が発生していることがわかる。このことから、MgO とAlの反応を少なくするため、Alの多量添加は、脱炭処理後で脱酸・還元処理前に行うのがよいという知見を得た。
【０００８】
従来、MgO を含む耐火物を用いた取鍋で高Al含有ステンレス鋼のVOD 処理を行った場合には、脱酸・還元処理後のスラグ中MgO 濃度の高い時期に大量（10〜120kg/t ）のAlを添加していたために、Alとスラグ中MgO が反応したものと考えられる。
また、本発明者らは、さらにスラグ組成を変化し、スラグ中MgO とAlの反応について調査した。Mg蒸気発生量とスラグ組成の関係を図２に示す。
【０００９】
図２から、スラグ中MgO 濃度およびCaO/Al2O3 が高くなるにしたがって、Mg蒸気の発生が多くなることがわかる。また、スラグCaO/Al2O3 が低くなるほどMg蒸気の発生量は少なくなるが、CaO/Al2O3 が0.5 未満では、スラグはAl2O3 が飽和し、完全に固化してしまうために、実際の処理には適さない。
このようなことから、Mg蒸気の発生を抑制し、Alを一括して多量に添加でき、処理時間を短縮するためには、Alの多量添加時のスラグ組成を、CaO/Al2O3 が0.5 〜0.7 の範囲で、かつMgO 濃度が０〜５wt％の範囲とすることが好適であるという知見を得た。
【００１０】
本発明は、上記した知見に基づいて構成されたものである。
すなわち、本発明は、MgO 含有耐火物を用いた精錬容器を使用する２次精錬設備で、Alを１〜10wt％含有する高Al含有ステンレス鋼を精錬するに際し、脱炭処理後であって脱酸・還元処理前に所定量のAlを添加することを特徴とする高Al含有ステンレス鋼の精錬方法であり、また、本発明では、前記所定量のAlを添加する際のスラグ組成を、CaO 濃度とAl2O3 濃度の比、CaO/Al2O3 が0.5 〜0.7 で、かつMgO 濃度が０または５wt％以下とするのが好ましい。
【００１１】
【発明の実施の形態】
本発明では、転炉あるいは電気炉で１次精錬を行ったステンレス鋼溶湯を、MgO 含有耐火物を用いた精錬容器を使用する２次精錬設備で精錬し、高Al含有のステンレス鋼を溶製する。２次精錬設備は、ＶＯＤ設備、あるいはＡＯＤ設備がいずれも好適に使用でき、また２次精錬設備で用いる精錬容器は、MgO 含有耐火物、を内張りした取鍋等の容器を使用する。具体的にはMgO 含有耐火物は、マグネシア−カーボン系耐火物が好ましい。
【００１２】
１次精錬されたステンレス鋼溶湯は、精錬容器に移され、２次精錬設備で２次精錬される。２次精錬について、ＶＯＤ処理を例に説明する。なお、本発明における２次精錬はＶＯＤ処理に限定されるものではないことは言うまでもない。
取鍋（精錬容器）に移されたステンレス鋼溶湯は、上吹きランスから酸素ガスを上吹きする脱炭処理を施されて、脱炭される。その後、還元剤を添加して、高真空下でArガスを底吹きし溶湯とスラグを攪拌し溶湯の脱酸とスラグの還元を行う脱酸・還元処理を施される。還元剤としては、Fe-Si 、あるいはAlが好ましい。
【００１３】
本発明で対象とする高Al含有ステンレス鋼は、Alを１〜10wt％含有するステンレス鋼である。
本発明では、Alの添加は、脱炭処理終了後で脱酸・還元処理前に行う。脱酸・還元処理後では、スラグ中のMgO 濃度が高く、Alの大量添加を行うとMg蒸気の発生が著しくなり、２次精錬作業が危険となる。ここで、Alの大量添加とは、Alを、10〜120kg/t-steel 一括して添加することをいう。
【００１４】
また、本発明では、Al添加時のスラグ組成を、CaO 濃度とAl2O3 濃度の比、CaO/Al2O3 が0.5 〜0.7 で、かつMgO 濃度が０〜５wt％とするのが好ましい。CaO/Al2O3 が0.5 未満では、スラグ中のAl2O3 が飽和し、スラグが完全に固化するため２次精錬が困難となる。また、CaO/Al2O3 が0.7 を超えると、Al添加時にMg蒸気の発生が顕著となる。スラグ組成の調整は、スラグ成分となるCaO 、Al2O3 を必要量添加し、あるいはさらにスラグ組成の分析を適宜行いその結果に基づいて、所定の範囲となるように添加物を装入することにより行うのが好ましい。
【００１５】
また、スラグ中のMgO 濃度が５wt％を超えると、Al添加時にMg蒸気の発生が顕著となる。このようなことから、Al添加時のスラグ組成は、CaO 濃度とAl2O3 濃度の比、CaO/Al2O3 を0.5 〜0.7 、かつMgO 濃度を０、または５wt％以下とするのが好ましい。当然ながら、Al添加時にMg蒸気の発生を防止するには、スラグ中MgO 濃度を０、すなわちスラグ中にMgO を含まないほうが好都合である。なお、精錬容器の溶損を防止する意味から、ドロマイト、れんが屑等を添加して少量のMgO をスラグ中に含有させることもある。
【００１６】
【実施例】
（比較例１）
転炉で１次精錬したステンレス鋼溶湯を、含MgO 耐火物を用いた取鍋に移し、160Ton VOD設備で２次精錬し、Alを５wt％含有する高Al含有ステンレス鋼とした。２次精錬は、酸素ガス吹精による脱炭処理後、真空中でFe-Si を7kg/t 添加し底吹きガスでの強撹拌による脱酸・還元処理を実施し、その後、大気圧下で38kg/tのAlを一括添加した。Al添加時のスラグ組成は、CaO/Al2O3 ＝1.1 、MgO ＝7.3 ％であった。その結果、Al添加後、スラグ中MgO とAlとの反応が生じ、Mg蒸気が発生し、それが酸化し大量のMgO の白煙が取鍋より舞い上がった。発火の危険を回避するため、そのまま処理を中止し、溶湯を廃塊とした。なお、スラグ中のMgO 濃度は、脱炭処理期で０〜３wt％、脱酸・還元処理期で5 〜10wt％であった。
【００１７】
（比較例２）
転炉で１次精錬したステンレス鋼溶湯を、含MgO 耐火物を用いた取鍋に移し、160Ton VOD設備で２次精錬し、Alを５wt％含有する高Al含有ステンレス鋼とした。２次精錬は、酸素ガス吹精による脱炭処理後、真空中でFe-Si を7kg/t 添加し底吹きガスでの強撹拌による脱酸・還元処理を実施し、その後、大気圧下で合計42kg/tのAlを、１回当たり6kg/t として７回に分割して添加した。Al添加時のスラグ組成はCaO/Al2O3 ＝1.2 、MgO ＝ 8.5wt％であった。その結果、比較例１のようなMg蒸気の発生はなく、安全に精錬することができた。しかし、７回に分割してAlを添加したために、Alを一括添加した場合に比べ処理時間が30min 程度長くなった。
【００１８】
（実施例１）
転炉で１次精錬したステンレス鋼溶湯を、含MgO 耐火物を用いた取鍋に移し、160Ton VOD設備で２次精錬し、Alを５wt％含有する高Al含有ステンレス鋼とした。２次精錬は、酸素ガス吹精による脱炭処理後、スラグ組成が、CaO/Al2O3 ＝0.65、MgO ＝ 2.3wt％の時、大気圧下で40kg/tのAlを一括添加し、脱酸・還元処理とAl量の調整を行った。その結果、Al添加後、比較例１のようなMg蒸気の発生はなく、安全にかつ迅速に精錬することができた。
【００１９】
（実施例２）
実施例１と同様に、160Ton VOD設備で２次精錬し、Alを５wt％含有する高Al含有ステンレス鋼とした。２次精錬は、酸素ガス吹精による脱炭処理後、スラグ組成が、CaO/Al2O3 ＝0.85、MgO ＝ 2.0wt％の時に、大気圧下で41kg/tのAlを一括添加し、脱酸・還元処理とAl量の調整を行った。その結果、Al添加後、比較例１のようなMg蒸気の多量発生はなく、安全にかつ迅速に精錬することができた。
【００２０】
【発明の効果】
以上のように、本発明によれば、安価な含MgO 耐火物を用いた取鍋（精錬容器）を使用するVOD 等の２次精錬設備において、Alを１〜10wt％含有する高Al含有ステンレス鋼を安全でかつ迅速に精錬することができ、製造コストを低減することが可能となり、産業上格段の効果を奏する。
【図面の簡単な説明】
【図１】 VOD 処理におけるスラグ中MgO 濃度の変化を示すグラフである。
【図２】 Mg蒸気発生におよぼすスラグ中MgO 濃度とCaO/Al2O3 の関係を示す説明図である。
【図３】 VOD 処理を模式的に示す説明図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for refining stainless steel, and more particularly to a method for secondary refining of high Al-containing stainless steel containing 1 to 10 wt% Al.
[0002]
[Prior art]
Conventionally, stainless steel is first refined in converters and electric furnaces, and then subjected to secondary refining consisting of decarburization, deoxidation and reduction in secondary refining equipment such as AOD and VOD. It is made. Conventionally, secondary refining of high Al-containing stainless steel containing 1 to 10 wt% Al has been performed in a ladle (smelting vessel) using Al 2 O 3 refractory. For example, in Japanese Patent Laid-Open No. 3-158410, in refining a high Al-containing stainless steel containing 3.0% by weight or more, when adjusting the Al in the steel to reduce the Mg concentration in the steel, the slag CaO Proposed a method for producing ferritic stainless steel by adjusting / Al 2 O 3 to 0.8 to 1.2 and adjusting SiO 2 + MgO + MnO in the slag to 5 wt% or less, and 5 wt% of SiO 2 + MgO + MnO in the slag. As a method of reducing the content of the smelting vessel to 95% or less, it is disclosed that Al 2 O 3 is 95% by weight or more.
[0003]
However, the ladle (refining vessel) using Al 2 O 3 refractory is a special pan, so it cannot be melted in a chance-free manner, and is expensive, leading to an increase in cost.
[0004]
[Problems to be solved by the invention]
On the other hand, when refining using a ladle (refining vessel) using an inexpensive MgO-containing refractory instead of a ladle (refining vessel) using Al 2 O 3 refractory, a ladle (smelting vessel) ) Eluates from the refractory, and the MgO concentration in the slag increases. When a large amount of Al (for example, 10 to 120 kg / t-steel) is added all at once in the presence of slag with high MgO concentration, MgO and Al in the slag are immediately added in the high concentration Al region near the slag. In order to react and generate Mg vapor | steam, there existed a problem that the Mg vapor | steam ignites by being oxidized in air | atmosphere. Therefore, when melting high Al-containing stainless steel in a ladle (refining vessel) using a refractory containing MgO, Al is required to be added in small portions, which greatly increases the processing time. It was extended and became one factor of cost up.
[0005]
In view of the above-mentioned problems of the prior art, the present invention provides a high-Al-containing stainless steel containing 1 to 10 wt% of Al in a safe and short time using a refining vessel using an inexpensive MgO-containing refractory. The purpose is to propose a method for refining high Al content stainless steel.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above-mentioned problems, the present inventors have come to realize that it is important to add Al at the time when the MgO concentration in the slag is the lowest in order to suppress the generation of Mg vapor. It was. In the conventional VOD treatment of high Al-containing stainless steel, as shown in Fig. 3, the decarburization treatment period in which oxygen gas is first blown to decarburize the molten steel, and then the oxygen blowing is stopped and reduced under high vacuum. It consists of a deoxidation / reduction treatment phase in which the agent (Fe-Si) is added, Ar gas is blown into the bottom, and the molten steel and slag are agitated while the molten metal is deoxidized and Cr in the slag is reduced.
[0007]
First, we investigated the change in MgO concentration in slag when Al-killed stainless steel was VOD treated with a ladle using MgO refractory. The result is shown in FIG.
From Fig. 1, it can be seen that during the decarburization process, the MgO concentration in the slag remained at a low level and there was no elution of MgO from the refractory. After that, during the deoxidation / reduction process in which a reducing agent is added and the slag and molten metal are stirred by bottom blowing gas, the MgO concentration in the slag has increased rapidly. You can see that it has occurred. From this, in order to reduce the reaction between MgO and Al, it was found that a large amount of Al should be added after decarburization and before deoxidation / reduction.
[0008]
Conventionally, when VOD treatment of high Al-containing stainless steel is performed in a ladle using a refractory containing MgO, a large amount (10 to 120 kg / t) of MgO in the slag after deoxidation / reduction treatment is high. ) Al was added, and it is thought that Al and MgO in the slag reacted.
In addition, the present inventors further changed the slag composition and investigated the reaction between MgO and Al in the slag. The relationship between the amount of Mg vapor generated and the slag composition is shown in FIG.
[0009]
FIG. 2 shows that the generation of Mg vapor increases as the MgO concentration in the slag and CaO / Al 2 O 3 increase. Also, the lower the slag CaO / Al 2 O 3, the smaller the amount of Mg vapor generated. However, when CaO / Al 2 O 3 is less than 0.5, the slag is completely solidified by Al 2 O 3 saturation. In addition, it is not suitable for actual processing.
Therefore, in order to suppress the generation of Mg vapor, add a large amount of Al at once, and shorten the processing time, the slag composition at the time of a large amount of Al addition is CaO / Al 2 O 3 It was found that it is preferable that the MgO concentration is in the range of 0.5 to 0.7 and the MgO concentration is in the range of 0 to 5 wt%.
[0010]
The present invention is configured based on the above-described knowledge.
That is, the present invention is a secondary refining facility using a refining vessel using a MgO-containing refractory, and when refining a high Al-containing stainless steel containing 1 to 10 wt. A refining method of high Al content stainless steel characterized by adding a predetermined amount of Al before the acid-reduction treatment, and in the present invention, the slag composition when adding the predetermined amount of Al, CaO It is preferable that the ratio of the concentration to the Al 2 O 3 concentration, CaO / Al 2 O 3 is 0.5 to 0.7, and the MgO concentration is 0 or 5 wt% or less.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, a molten stainless steel that has undergone primary refining in a converter or electric furnace is refined in a secondary refining facility that uses a refining vessel that uses a refractory containing MgO, and high-Al-containing stainless steel is melted. To do. As the secondary refining equipment, either the VOD equipment or the AOD equipment can be suitably used, and the refining vessel used in the secondary refining equipment uses a container such as a ladle lined with MgO-containing refractory. Specifically, the MgO-containing refractory is preferably a magnesia-carbon refractory.
[0012]
The first refined stainless steel melt is transferred to a refining vessel and secondarily refined by a secondary refining facility. Secondary refining will be described using the VOD process as an example. Needless to say, the secondary refining in the present invention is not limited to the VOD process.
The molten stainless steel transferred to the ladle (smelting vessel) is decarburized by being subjected to a decarburization process in which oxygen gas is blown up from an upper blowing lance. Thereafter, a reducing agent is added, Ar gas is blown to the bottom under high vacuum, and the molten metal and slag are stirred to perform deoxidation / reduction treatment for deoxidizing the molten metal and reducing the slag. As the reducing agent, Fe-Si or Al is preferable.
[0013]
The high Al-containing stainless steel targeted in the present invention is a stainless steel containing 1 to 10 wt% of Al.
In the present invention, Al is added after the decarburization process and before the deoxidation / reduction process. After the deoxidation / reduction treatment, the MgO concentration in the slag is high, and if a large amount of Al is added, the generation of Mg vapor becomes significant and the secondary refining work becomes dangerous. Here, the mass addition of Al means that 10 to 120 kg / t-steel is added all at once.
[0014]
In the present invention, the slag composition at the time of Al addition is preferably a ratio of CaO concentration to Al 2 O 3 concentration, CaO / Al 2 O 3 is 0.5 to 0.7, and MgO concentration is 0 to 5 wt%. . If CaO / Al 2 O 3 is less than 0.5, Al 2 O 3 in the slag is saturated and the slag is completely solidified, making secondary refining difficult. On the other hand, if CaO / Al 2 O 3 exceeds 0.7, the generation of Mg vapor becomes remarkable when Al is added. To adjust the slag composition, add necessary amounts of CaO and Al 2 O 3 as slag components, or further analyze the slag composition as appropriate, and insert the additives so as to be within the predetermined range based on the results. Is preferably performed.
[0015]
If the MgO concentration in the slag exceeds 5 wt%, the generation of Mg vapor becomes significant when Al is added. For this reason, the slag composition at the time of Al addition is such that the ratio of CaO concentration to Al 2 O 3 concentration, CaO / Al 2 O 3 is 0.5 to 0.7, and MgO concentration is 0 or 5 wt% or less. preferable. Of course, in order to prevent the generation of Mg vapor when Al is added, it is advantageous that the MgO concentration in the slag is 0, that is, MgO is not contained in the slag. In order to prevent melting of the smelting vessel, a small amount of MgO may be contained in the slag by adding dolomite, brick scraps or the like.
[0016]
【Example】
(Comparative Example 1)
The stainless steel melt first refined in the converter was transferred to a ladle using MgO refractory, and secondarily refined with a 160Ton VOD facility to obtain a high Al content stainless steel containing 5 wt% Al. In secondary refining, after decarburization treatment with oxygen gas blowing, Fe-Si was added at 7kg / t in vacuum and deoxidation / reduction treatment was performed by strong stirring with bottom blowing gas, and then under atmospheric pressure. 38 kg / t Al was added all at once. The slag composition when Al was added was CaO / Al 2 O 3 = 1.1 and MgO = 7.3%. As a result, after the addition of Al, the reaction between MgO and Al in the slag occurred, and Mg vapor was generated, which oxidized and a large amount of MgO white smoke rose from the ladle. In order to avoid the risk of ignition, the treatment was stopped as it was and the molten metal was turned into a lump. The MgO concentration in the slag was 0 to 3 wt% during the decarburization treatment period and 5 to 10 wt% during the deoxidation / reduction treatment period.
[0017]
(Comparative Example 2)
The stainless steel melt first refined in the converter was transferred to a ladle using MgO refractory, and secondarily refined with a 160Ton VOD facility to obtain a high Al content stainless steel containing 5 wt% Al. In secondary refining, after decarburization treatment with oxygen gas blowing, Fe-Si was added at 7kg / t in vacuum and deoxidation / reduction treatment was performed by strong stirring with bottom blowing gas, and then under atmospheric pressure. A total of 42 kg / t of Al was added in 6 batches at 6 kg / t. Slag composition during Al added CaO / Al 2 O 3 = 1.2 , were MgO = 8.5 wt%. As a result, there was no generation of Mg vapor as in Comparative Example 1, and it could be refined safely. However, since Al was added in seven portions, the treatment time was about 30 minutes longer than when Al was added all at once.
[0018]
Example 1
The stainless steel melt that was primarily refined in the converter was transferred to a ladle using MgO refractory and secondarily refined with a 160Ton VOD facility to obtain a high Al content stainless steel containing 5 wt% Al. In secondary refining, after decarburization treatment with oxygen gas blowing, when slag composition is CaO / Al 2 O 3 = 0.65, MgO = 2.3wt%, 40kg / t Al is added under atmospheric pressure. Deoxidation / reduction treatment and adjustment of Al amount were performed. As a result, after the addition of Al, there was no generation of Mg vapor as in Comparative Example 1, and it was possible to refine safely and quickly.
[0019]
(Example 2)
In the same manner as in Example 1, secondary refining was performed using a 160 Ton VOD facility to obtain a high Al-containing stainless steel containing 5 wt% Al. In secondary refining, after decarburization treatment with oxygen gas blowing, when slag composition is CaO / Al 2 O 3 = 0.85 and MgO = 2.0wt%, 41kg / t Al is added at a time under atmospheric pressure. Deoxidation / reduction treatment and adjustment of Al amount were performed. As a result, after the addition of Al, a large amount of Mg vapor was not generated as in Comparative Example 1, and it could be refined safely and quickly.
[0020]
【The invention's effect】
As described above, according to the present invention, in a secondary refining equipment such as VOD using a ladle (smelting vessel) using an inexpensive MgO refractory, a high Al content stainless steel containing 1 to 10 wt% Al. Steel can be refined safely and quickly, and the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a graph showing changes in MgO concentration in slag during VOD treatment.
FIG. 2 is an explanatory diagram showing the relationship between MgO concentration in slag and CaO / Al 2 O 3 affecting Mg vapor generation.
FIG. 3 is an explanatory diagram schematically showing VOD processing.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27810698A JP3893769B2 (en) | 1998-09-30 | 1998-09-30 | Method for refining high Al content stainless steel |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27810698A JP3893769B2 (en) | 1998-09-30 | 1998-09-30 | Method for refining high Al content stainless steel |
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| Publication Number | Publication Date |
|---|---|
| JP2000104112A JP2000104112A (en) | 2000-04-11 |
| JP3893769B2 true JP3893769B2 (en) | 2007-03-14 |
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| JP27810698A Expired - Fee Related JP3893769B2 (en) | 1998-09-30 | 1998-09-30 | Method for refining high Al content stainless steel |
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| Country | Link |
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| JP (1) | JP3893769B2 (en) |
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| JP2000104112A (en) | 2000-04-11 |
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