JPH11131131A - Method of manufacturing steel containing nitrogen - Google Patents
Method of manufacturing steel containing nitrogenInfo
- Publication number
- JPH11131131A JPH11131131A JP29394997A JP29394997A JPH11131131A JP H11131131 A JPH11131131 A JP H11131131A JP 29394997 A JP29394997 A JP 29394997A JP 29394997 A JP29394997 A JP 29394997A JP H11131131 A JPH11131131 A JP H11131131A
- Authority
- JP
- Japan
- Prior art keywords
- nitrogen
- molten steel
- vacuum
- steel
- degassing
- 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.)
- Withdrawn
Links
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract 17
- 229910000831 Steel Inorganic materials 0.000 title claims abstract 14
- 239000010959 steel Substances 0.000 title claims abstract 14
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract 8
- 238000004519 manufacturing process Methods 0.000 title claims abstract 3
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims abstract 8
- 238000007872 degassing Methods 0.000 claims abstract 5
- 238000009849 vacuum degassing Methods 0.000 claims abstract 5
- 238000007664 blowing Methods 0.000 claims abstract 4
- 239000007789 gas Substances 0.000 claims abstract 4
- 238000000034 method Methods 0.000 claims 6
- 238000002844 melting Methods 0.000 claims 2
- 230000008018 melting Effects 0.000 claims 2
- 238000003723 Smelting Methods 0.000 claims 1
- 229910001873 dinitrogen Inorganic materials 0.000 abstract 1
Landscapes
- 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、窒素含有鋼の溶製
方法に関し、特に、真空脱ガス装置内で、溶鋼に窒素を
添加する技術である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing nitrogen-containing steel, and more particularly to a technique for adding nitrogen to molten steel in a vacuum degassing apparatus.
【０００２】[0002]
【従来の技術】一般に、窒素（以下、Ｎを用いる場合が
多い）含有鋼の製造に際して溶鋼中にＮを添加するに
は、特開平７−２４２９２７号公報が開示したように、
Ｎ含有合金鉄を脱ガス処理した後の溶鋼中に投入した
り、あるいは特開昭５６−２５９１９号公報が開示した
ように、所謂ＲＨ脱ガス装置（図１参照）で用いる環流
ガス７をＮ2 ガスとして、溶鋼６中に吹込む方法が知ら
れている。また、特開平２−１５６０１５号公報は、脱
ガス装置１内の圧力を検出し、該検出内圧に応じて脱ガ
ス装置１内の湯面に向け、装置壁に設けたノズルを介し
て窒素ガスを吹き付ける方法を開示している。2. Description of the Related Art Generally, in order to add N to molten steel at the time of producing a steel containing nitrogen (hereinafter, N is often used), as disclosed in Japanese Patent Application Laid-Open No. 7-242927,
The N-containing ferromagnetic iron is charged into molten steel after degassing, or the reflux gas 7 used in a so-called RH degassing apparatus (see FIG. 1) as disclosed in Japanese Patent Application Laid-Open No. 56-25919 is N. A method of injecting into molten steel 6 as two gases is known. Japanese Patent Application Laid-Open No. Hei 2-156015 discloses a technique in which the pressure in a degassing device 1 is detected, and the nitrogen gas is directed toward a molten metal level in the degassing device 1 through a nozzle provided on the device wall in accordance with the detected internal pressure. Is disclosed.
【０００３】しかしながら、特開平７−２４２９２７号
公報記載のＮ含有合金鉄による添加方法では、これら添
加用合金鉄が高価であること、及び該合金鉄中のＮ分以
外の合金成分が上昇することを考慮し、該合金鉄の添加
量を調整しなければならないという問題があった。ま
た、特開昭５６−２５９１９号公報記載の所謂環流ガス
７をＮ2 ガスにする添加方法では、環流ガス流量が最大
でも３〜５Ｎｍ3 ／分と限られた量であるので、高Ｎ含
有鋼を製造するには、加窒に長時間を要するという問題
があった。そのため、脱ガス処理中に溶鋼温度を低下さ
せる可能性があり、該処理の初期に十分高い溶鋼温度を
確保していなければならないという問題があった。[0003] However, in the method of adding N-containing ferro-alloy described in Japanese Patent Application Laid-Open No. 7-242927, these additional ferro-alloys are expensive and alloy components other than N in the ferro-alloy increase. Therefore, there is a problem that the addition amount of the ferromagnetic iron must be adjusted in consideration of the above. In addition, in the method of adding the so-called reflux gas 7 to N 2 gas described in JP-A-56-25919, since the reflux gas flow rate is limited to a maximum of 3 to 5 Nm 3 / min, a high N content is obtained. In order to produce steel, there is a problem that it takes a long time for nitriding. Therefore, there is a possibility that the temperature of the molten steel may be lowered during the degassing process, and there is a problem that a sufficiently high temperature of the molten steel must be secured at the beginning of the process.
【０００４】さらに、特開平２−１５６０１５号公報記
載の方法は、溶鋼に合金材料を添加する際に、脱ガス装
置内で溶鋼が起こす反応が変化することによって、該装
置内の窒素分圧が目標値から外れることを防止しようと
するものである。しかしながら、この方法によっても窒
素濃度の低い溶鋼に気相側から加窒する際には、必ずし
も設定された装置内窒素分圧によって窒素濃度が一義的
に決まらず、溶鋼中の窒素濃度のばらつきが大きい上
に、加窒に長時間を要するケースも見いだされた。Furthermore, the method described in Japanese Patent Application Laid-Open No. 2-156015 discloses that when an alloy material is added to molten steel, the reaction caused by the molten steel in the degassing apparatus changes, so that the nitrogen partial pressure in the apparatus is reduced. It is intended to prevent deviation from the target value. However, even with this method, when nitriding the molten steel with a low nitrogen concentration from the gas phase side, the nitrogen concentration is not necessarily determined uniquely by the set nitrogen partial pressure in the apparatus, and the nitrogen concentration in the molten steel varies. Some cases were large and took a long time to nitridate.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、かかる事情
に鑑み、溶鋼への加窒を短時間で、且つ簡単な設備で安
価に実施可能とする窒素含有鋼の溶製方法を提供するこ
とを目的としている。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method for producing nitrogen-containing steel capable of performing nitrification of molten steel in a short time with simple equipment at a low cost. It is an object.
【０００６】[0006]
【課題を解決するための手段】発明者は、上記目的を達
成するため、脱ガス真空装置内での窒素の挙動を鋭意研
究し、溶鋼への加窒は、湯面から雰囲気への脱窒と、ラ
ンスから吹き付けた窒素ガスの湯面到達時に有する局所
的圧力による溶鋼への窒素吸収とのバランスによって決
まることを見い出した。そして、この知見を具現化した
のが本発明である。Means for Solving the Problems In order to achieve the above object, the inventor has studied diligently the behavior of nitrogen in a degassing vacuum apparatus. And the balance between the nitrogen pressure sprayed from the lance and the absorption of nitrogen into the molten steel by the local pressure of the gas when it reaches the surface. The present invention embodies this finding.
【０００７】すなわち、本発明は、真空脱ガス装置内
で、溶鋼を脱ガスした後、該溶鋼中に窒素を添加するに
際して、前記脱ガス装置内の真空度を、窒素が該装置外
に抜けないように保持しつつ、上吹きランスを介して窒
素又は窒素含有ガスを前記溶鋼の表面に吹付けることを
特徴とする窒素含有鋼の溶製方法である。また、本発明
は、前記真空脱ガス装置内の真空度を、１〜２００ｔｏ
ｒｒとしたり、あるいは前記上吹ランスの先端位置を、
溶鋼の静止浴面から１．５ｍ以内の高さとすることを特
徴とする窒素含有鋼の溶製方法である。That is, according to the present invention, when degassing molten steel in a vacuum degassing apparatus and then adding nitrogen to the molten steel, the nitrogen in the degassing apparatus is released from the vacuum degree inside the degassing apparatus. A method for producing nitrogen-containing steel, characterized in that nitrogen or a nitrogen-containing gas is blown onto the surface of the molten steel through an upper blowing lance, while maintaining the molten steel. Further, the present invention provides that the degree of vacuum in the vacuum degassing apparatus is 1 to 200 to
rr, or the tip position of the upper blowing lance,
A method for melting nitrogen-containing steel, wherein the height of the steel is set within 1.5 m from a stationary bath surface of the molten steel.
【０００８】さらに、本発明は、前記上吹ランスを、ラ
バール・ノズル・ランスとすることを特徴とする窒素含
有鋼の溶製方法でもある。また、本発明は真空脱ガス装
置としてＲＨ脱ガス装置を用いることを特徴とする窒素
含有鋼の溶製方法でもある。本発明では、真空脱ガス装
置内で、上吹きランス、とりわけ超音速ガス・ジェット
を伴うラバール・ノズル・ランスを介して、窒素ガスを
溶鋼面に吹き付けるようにしたので、該装置内の平均圧
力よりもはるかに高い圧力を溶鋼面上に形成することが
でき、溶鋼中の窒素濃度は、この局所的な吹き付け位置
での湯面上窒素分圧に支配されるようになる。また、装
置内の平均窒素分圧は、単に、雰囲気への窒素の逸脱を
防ぐ程度の圧力にとどめ、加窒そのものは、前記上吹き
ランスからの窒素ガスにで行うようにしたので、窒素ガ
スを大流量の２０〜５０Ｎｍ3／ｍｉｎとすることがで
き、従来にない高速、且つ高精度で溶鋼中への窒素添加
が実現できるようになる。その結果、溶鋼への加窒時間
が従来より格段と短くてすみ、溶鋼の環流撹拌に起因し
た温度降下が小さくてすみ、安定、且つ安価に窒素含有
鋼の溶製ができるようになる。Further, the present invention is also a method for melting nitrogen-containing steel, wherein the upper blowing lance is a Laval nozzle lance. The present invention is also a method for melting nitrogen-containing steel, wherein an RH degassing device is used as a vacuum degassing device. In the present invention, in the vacuum degassing apparatus, nitrogen gas is blown to the molten steel surface through a top blowing lance, particularly a Laval nozzle lance with a supersonic gas jet, so that the average pressure in the apparatus is increased. A much higher pressure can be formed on the molten steel surface, and the nitrogen concentration in the molten steel becomes dominated by the partial pressure of nitrogen on the molten steel surface at this local spray position. In addition, the average nitrogen partial pressure in the apparatus was simply set to a pressure that prevented the escape of nitrogen into the atmosphere, and the nitriding itself was performed with nitrogen gas from the top blowing lance. Can be set to a large flow rate of 20 to 50 Nm 3 / min, and nitrogen addition to molten steel can be realized with high speed and high accuracy which has not been achieved conventionally. As a result, the time for nitriding the molten steel can be significantly shorter than before, the temperature drop due to the reflux stirring of the molten steel can be small, and the nitrogen-containing steel can be smelted in a stable and inexpensive manner.
【０００９】[0009]
【発明の実施の形態】本発明は、まず、転炉、電気炉等
の精錬炉で精錬され、取鍋２に出鋼された溶鋼６を、そ
のまま図１に例示する真空脱ガス装置１（ここではＲＨ
脱ガス装置の例を示す）にセットして、脱ガスを行う。
その際、鋼材の用途によっては、さらなる脱硫、脱炭等
を行っても良い。次に、該溶鋼６中に窒素を添加するこ
とになるが、ＲＨ脱ガス装置１内の真空度を、窒素が装
置外に抜けないように保持することが必要である。そし
て、別途、該脱ガス装置１の上方に設置した上吹きラン
ス４を、その先端が溶鋼面上のある位置になるよう降下
させ、窒素又は窒素含有ガスを前記溶鋼６の表面に吹付
けるのである。BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, first, a molten steel 6 refined in a refining furnace such as a converter or an electric furnace and discharged to a ladle 2 is directly subjected to a vacuum degassing apparatus 1 (FIG. 1). Here RH
(The example of a degassing apparatus is shown), and degassing is performed.
At that time, depending on the use of the steel material, further desulfurization, decarburization, or the like may be performed. Next, nitrogen is added to the molten steel 6, but it is necessary to maintain the degree of vacuum in the RH degassing device 1 so that nitrogen does not escape outside the device. Then, separately, the upper blowing lance 4 installed above the degassing device 1 is lowered so that its tip is at a certain position on the molten steel surface, and nitrogen or a nitrogen-containing gas is blown onto the surface of the molten steel 6. is there.
【００１０】その際、ＲＨ脱ガス装置１内の真空度を、
窒素が装置外に抜けないよう１〜２００ｔｏｒｒとする
ことが好ましい。発明者の研究によれば、真空度と鋼中
への加窒量（窒素上昇量）との間には、図２に示すよう
な曲線関係がある。この関係によれば、真空度が１ｔｏ
ｒｒ未満では、溶鋼６中で加窒が進行しないからであ
り、２００ｔｏｒｒを超えると、加窒速度が飽和して、
それ以上真空度をあげても無駄になるからである。At this time, the degree of vacuum in the RH degassing device 1 is
The pressure is preferably set to 1 to 200 torr so that nitrogen does not escape from the apparatus. According to the study of the inventor, there is a curve relationship as shown in FIG. 2 between the degree of vacuum and the amount of nitriding in steel (the amount of increase in nitrogen). According to this relationship, the degree of vacuum is 1 to
If it is less than rr, nitriding does not progress in the molten steel 6, and if it exceeds 200 torr, the nitriding rate is saturated,
This is because increasing the degree of vacuum beyond that is useless.
【００１１】また、本発明で、上吹ランス４の先端位置
を、溶鋼６の静止浴面から１．５ｍ以内の高さを好まし
いとするのは、上吹きランス４の先端位置（高さ）によ
って、吹き付ける窒素の湯面上での局所的な圧力が変わ
り、それが加窒量に影響を与えるからである。発明者の
研究では、その関係は図３に示すようになる。さらに、
発明者は、溶鋼６の加窒量に及ぼす窒素流量の影響も調
査し、図４の関係を得た。図４によれば、上吹きランス
６を用いることで、大流量の窒素ガスを吹き付け可能と
なり、かなり大きな加窒量が得られるようになる。加え
て、本発明の実施に際し、上吹ランス６としてラバール
・ノズル・ランスを採用したところ、超音波の発生で溶
鋼６面を振動し、加窒速度を促進することができた。Further, in the present invention, the tip position of the upper blowing lance 4 is preferably set to a height within 1.5 m from the stationary bath surface of the molten steel 6 because of the tip position (height) of the upper blowing lance 4. This changes the local pressure of the sprayed nitrogen on the surface of the molten metal, which affects the amount of nitriding. According to the inventors' research, the relationship is as shown in FIG. further,
The inventor also investigated the effect of the nitrogen flow rate on the amount of nitriding of the molten steel 6, and obtained the relationship shown in FIG. According to FIG. 4, the use of the upper blowing lance 6 makes it possible to blow a large amount of nitrogen gas, and a considerably large amount of nitriding can be obtained. In addition, when a Laval nozzle lance was employed as the upper lance 6 in the practice of the present invention, the surface of the molten steel 6 was vibrated by the generation of ultrasonic waves, and the nitriding speed could be increased.
【００１２】[0012]
【実施例】転炉精錬で得た同一組成の低炭素溶鋼を用
い、目標窒素量を種々変更して窒素含有鋼を溶製した。
ヒート・サイズは２３０ｔとし、本発明の実施例１〜４
については目標Ｎ量を変化させ、各水準とも５０チャー
ジ実験した。なお、比較例１は、同じ２３０ｔの溶鋼を
特開平２−１５６０１５号公報に記載された方法によっ
て、５０チャージ処理試験した例である。また、比較例
２は、同様に２３０ｔの溶鋼を特開昭５６−２５９１９
号公報に記載された方法によって、５チャージを処理試
験した例である。さらに、使用したＲＨ真空脱ガス装置
１は、図１に示したものと同一型式である。加窒条件と
操業結果を一括して表１及び表２に示す。EXAMPLE A low-carbon molten steel of the same composition obtained by converter refining was used to produce a nitrogen-containing steel by changing the target nitrogen amount in various ways.
The heat size was 230 t, and Examples 1-4 of the present invention were used.
As for, the target N amount was changed, and a 50 charge experiment was performed for each level. Comparative Example 1 is an example in which the same 230 t of molten steel was subjected to a 50 charge treatment test by the method described in JP-A-2-156015. In Comparative Example 2, 230 ton of molten steel was similarly prepared in Japanese Patent Laid-Open No. 56-25919.
This is an example in which five charges are processed and tested by the method described in Japanese Patent Application Laid-Open Publication No. H10-260,036. Further, the RH vacuum degassing apparatus 1 used is of the same type as that shown in FIG. Tables 1 and 2 collectively show the nitriding conditions and operation results.
【００１３】表１及び２によれば、本発明を適用する
と、従来法による場合に比べ、操業時間が著しく短縮で
き、それに伴い、溶鋼の温度効果も小さいうえ、目標的
中率が高いことが確認できた。According to Tables 1 and 2, when the present invention is applied, the operation time can be remarkably reduced as compared with the case of the conventional method, and accordingly, the temperature effect of the molten steel is small and the target medium rate is high. It could be confirmed.
【００１４】[0014]
【表１】 [Table 1]
【００１５】[0015]
【表２】 [Table 2]
【００１６】なお、上記実施例は、真空脱ガス装置に所
謂ＲＨ方式のものを使用したが、本発明は、それに限ら
ず、ＤＨ方式、ＶＯＤ方式等にも適用できることは言う
までもない。Although the above-described embodiment uses a so-called RH type vacuum degassing apparatus, it goes without saying that the present invention is not limited to this and can be applied to a DH type, a VOD type and the like.
【００１７】[0017]
【発明の効果】以上述べたように、本発明により、溶鋼
への加窒時間が従来より格段と短く、溶鋼の環流撹拌に
起因した温度降下も小さくてすむようになった。その結
果、窒素含有鋼が、安定して、且つ安価に溶製できるよ
うになった。As described above, according to the present invention, the nitriding time for molten steel is much shorter than before, and the temperature drop caused by the reflux stirring of the molten steel can be reduced. As a result, nitrogen-containing steel can be stably and inexpensively melted.
【図１】本発明を実施するＲＨ真空脱ガス装置を示す縦
断面図である。FIG. 1 is a longitudinal sectional view showing an RH vacuum degassing apparatus embodying the present invention.
【図２】真空度と鋼中窒素の上昇量との関係を示す図で
ある。FIG. 2 is a diagram showing the relationship between the degree of vacuum and the amount of increase in nitrogen in steel.
【図３】ランス高さと鋼中窒素の上昇量との関係を示す
図である。FIG. 3 is a diagram showing a relationship between a lance height and an amount of rise of nitrogen in steel.
【図４】窒素ガス流量と鋼中窒素の上昇量との関係を示
す図である。FIG. 4 is a diagram showing a relationship between a nitrogen gas flow rate and a rise amount of nitrogen in steel.
１ ＲＨ脱ガス装置 ２ 取鍋 ３ 上昇管 ４ 上吹きランス ５ 窒素ガス（窒素含有ガス） ６ 溶鋼 ７ 還流ガス（通常、アルゴン） ８ 下降管 DESCRIPTION OF SYMBOLS 1 RH degassing apparatus 2 Ladle 3 Ascending pipe 4 Top blowing lance 5 Nitrogen gas (nitrogen containing gas) 6 Molten steel 7 Reflux gas (usually argon) 8 Descending pipe
Claims (5)
後、該溶鋼中に窒素を添加するに際して、 前記真空脱ガス装置内の真空度を、窒素が該装置外に抜
けないように保持しつつ、上吹きランスを介して窒素又
は窒素含有ガスを前記溶鋼の表面に吹付けることを特徴
とする窒素含有鋼の溶製方法。After degassing molten steel in a vacuum degassing apparatus, when adding nitrogen to the molten steel, the degree of vacuum in the vacuum degassing apparatus is adjusted so that nitrogen does not escape outside the apparatus. A method for producing nitrogen-containing steel, comprising blowing nitrogen or a nitrogen-containing gas onto the surface of the molten steel while holding the molten steel through an upper blowing lance.
２００ｔｏｒｒとすることを特徴とする請求項１記載の
窒素含有鋼の溶製方法。2. The vacuum degree in the vacuum degassing apparatus is set to 1 to
The method for melting nitrogen-containing steel according to claim 1, wherein the pressure is set to 200 torr.
止浴面から１．５ｍ以内の高さとすることを特徴とする
請求項１又は２記載の窒素含有鋼の溶製方法。3. The method for smelting nitrogen-containing steel according to claim 1, wherein a position of a tip of the upper blowing lance is set to a height within 1.5 m from a stationary bath surface of the molten steel.
ランスとすることを特徴とする請求項１〜３のいずれか
に記載の窒素含有鋼の溶製方法。4. The method according to claim 1, wherein the upper lance is provided with a Laval nozzle nozzle.
The method for melting nitrogen-containing steel according to any one of claims 1 to 3, wherein the method is a lance.
あることを特徴とする請求項１〜４のいずれかに記載の
窒素含有鋼の溶製方法。5. The method according to claim 1, wherein the vacuum degassing device is an RH degassing device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29394997A JPH11131131A (en) | 1997-10-27 | 1997-10-27 | Method of manufacturing steel containing nitrogen |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29394997A JPH11131131A (en) | 1997-10-27 | 1997-10-27 | Method of manufacturing steel containing nitrogen |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11131131A true JPH11131131A (en) | 1999-05-18 |
Family
ID=17801271
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29394997A Withdrawn JPH11131131A (en) | 1997-10-27 | 1997-10-27 | Method of manufacturing steel containing nitrogen |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11131131A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CZ298889B6 (en) * | 2004-07-23 | 2008-03-05 | Trinecké železárny a. s. | Process for producing steels with guaranteed amount of nitrogen |
-
1997
- 1997-10-27 JP JP29394997A patent/JPH11131131A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CZ298889B6 (en) * | 2004-07-23 | 2008-03-05 | Trinecké železárny a. s. | Process for producing steels with guaranteed amount of nitrogen |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20050104 |