JPH0463221A - Method for reducing nitrogen in vacuum refining of molten steel - Google Patents
Method for reducing nitrogen in vacuum refining of molten steelInfo
- Publication number
- JPH0463221A JPH0463221A JP17238890A JP17238890A JPH0463221A JP H0463221 A JPH0463221 A JP H0463221A JP 17238890 A JP17238890 A JP 17238890A JP 17238890 A JP17238890 A JP 17238890A JP H0463221 A JPH0463221 A JP H0463221A
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- gas
- degassing
- vacuum chamber
- nitrogen
- 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.)
- Granted
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 65
- 239000010959 steel Substances 0.000 title claims abstract description 65
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 58
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000007670 refining Methods 0.000 title claims description 6
- 239000007789 gas Substances 0.000 claims abstract description 38
- 238000007872 degassing Methods 0.000 claims abstract description 30
- 238000005507 spraying Methods 0.000 claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 abstract description 16
- 238000007664 blowing Methods 0.000 abstract description 7
- 238000007654 immersion Methods 0.000 abstract description 3
- 239000007921 spray Substances 0.000 abstract description 2
- 230000000977 initiatory effect Effects 0.000 abstract 1
- 238000010992 reflux Methods 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 238000009849 vacuum degassing Methods 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 238000005261 decarburization Methods 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は溶鋼の真空精錬における溶鋼中の窒素濃度（以
下（Ｎ）と記す）の低減方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for reducing the nitrogen concentration (hereinafter referred to as (N)) in molten steel in vacuum refining of molten steel.
（従来技術）
一般に、鋼材品質に対する要求は、益々厳し〈従来の〔
Ｐ〕、（Ｓ）等の低減に加えて、最近特に、低〔Ｃ〕、
（０）、 （Ｎ）の低下をも含めた高純度鋼が要求され
ている。この要求に呼応するために、鋼材の溶製におい
て、溶銑予備処理あるいは二次精錬等を駆使して、〔Ｐ
〕、［：Ｓ）、 〔Ｃ）、 （０）の低減化に努め、か
なり高純度な鋼の溶製が可能になっている。(Prior art) In general, requirements for steel material quality are becoming increasingly strict.
In addition to reductions in P], (S), etc., recently, especially low [C],
There is a demand for high-purity steel that also reduces (0) and (N). In order to meet this demand, we are making full use of hot metal pretreatment and secondary refining in the melting of steel materials.
], [:S), [C), and (0), it has become possible to produce steel of considerably high purity.
低〔Ｎ）化に関しても、いくつかの方策が提案されてい
る。例えば、真空脱ガス処理により低窒素鋼を溶製する
ために、真空槽内の溶鋼面へ、鉄鉱石、計鉱石等の固体
酸素源、あるいは、酸素ガスを吹き付けて脱炭反応を起
こし、発生したＣＯガス気泡中へ窒素を吸収させ、脱窒
を促進する方法が特開昭６０−１８４６１８号公報、特
開昭６０−１８４６１９号公報等に記載されている。し
かし、これらの方法では、極低（Ｎ）領域まで脱窒を促
進するほどの脱炭反応を進行させるためには、溶鋼中の
過剰酸素濃度を高める必要がある。しかしながら、溶鋼
中の酸素濃度を高めることは、脱酸後の酸化物系介在物
の増加という品質上好ましくない結果をもたらす。Several measures have also been proposed regarding lowering [N]. For example, in order to produce low-nitrogen steel by vacuum degassing, a solid oxygen source such as iron ore, gauge ore, or oxygen gas is blown onto the molten steel surface in a vacuum chamber to cause a decarburization reaction. A method for accelerating denitrification by absorbing nitrogen into CO gas bubbles is described in JP-A-60-184618 and JP-A-60-184619. However, in these methods, it is necessary to increase the excess oxygen concentration in the molten steel in order to advance the decarburization reaction to the extent that denitrification is promoted to the extremely low (N) region. However, increasing the oxygen concentration in molten steel brings about an increase in oxide inclusions after deoxidation, which is unfavorable in terms of quality.
さらに、酸素濃度を１１００ｐｐ以上に高めた場合には
脱窒反応の界面抵抗が著しく増大し、脱窒反応の進行が
期待できないという結果をもたらす。Further, when the oxygen concentration is increased to 1100 pp or more, the interfacial resistance for the denitrification reaction increases significantly, resulting in that the denitrification reaction cannot be expected to progress.
一方、還流管中の溶鋼あるいは取鍋内の溶鋼にＡｒ等の
不活性ガスを吹き込むことにより、ガス気泡−溶鋼界面
を通じた脱窒反応を進行させようという提案もある。こ
ういった提案では、真空脱ガス槽の内部は真空雰囲気で
あり、真空槽内の溶鋼自由表面においては脱窒反応が生
じているものとされていた。しかしながら１本発明者ら
が、真空槽内の窒素分圧について調査したところ、真空
槽内の溶鋼自由表面における窒素分圧は、かなり高いこ
とが明らかになった。たとえば、１６００℃において２
０ｐｐｍの窒素濃度と平衡する窒素分圧は、０．００２
ａｔ鳳であるが、実際の真空槽内の溶鋼自由表面におけ
る窒素分圧は、これよりも高い０．００２１ｓｔｍ程度
のレベルであり、従って、〔Ｎ〕が２０ｐｐｍ以下の低
窒素濃度領域では、溶鋼自由表面においてはかえって吸
窒反応が進行していることになる。On the other hand, there is also a proposal to advance the denitrification reaction through the gas bubble-molten steel interface by blowing an inert gas such as Ar into the molten steel in the reflux pipe or the molten steel in the ladle. In these proposals, the interior of the vacuum degassing tank is a vacuum atmosphere, and it is assumed that a denitrification reaction occurs on the free surface of the molten steel inside the vacuum tank. However, when the present inventors investigated the nitrogen partial pressure within the vacuum chamber, it became clear that the nitrogen partial pressure at the free surface of the molten steel within the vacuum chamber was quite high. For example, 2 at 1600℃
The nitrogen partial pressure in equilibrium with a nitrogen concentration of 0 ppm is 0.002
However, the actual nitrogen partial pressure on the free surface of molten steel in a vacuum chamber is higher than this, at a level of about 0.0021stm. Therefore, in a low nitrogen concentration region where [N] is 20 ppm or less, molten steel On the contrary, the nitrification reaction is progressing on the free surface.
この問題の解決として、特開昭６３−１５７８１４号公
報では、真空槽内の溶鋼表面にＡｒガスを吹き付けるこ
とを提案している。この方法では、脱ガス処理開始から
処理終了まで、１５．３〜３０．６Ｎｆｉ／ｌｏｎ−ｍ
ｉｎのＡｒガスを終始吹き付けることにより、（Ｎ）が
２０ｐｐｍ以下の低窒素鋼を安定溶製できるとしている
。As a solution to this problem, Japanese Patent Application Laid-Open No. 63-157814 proposes spraying Ar gas onto the surface of molten steel in a vacuum chamber. This method requires 15.3 to 30.6 Nfi/lon-m from the start of degassing treatment to the end of treatment.
It is said that low-nitrogen steel with (N) content of 20 ppm or less can be stably produced by spraying Ar gas of 100 mL throughout the process.
しかしながら、高価なＡｒガスを長時間、大量に消費す
ることは、経済的な観点からは極めて不利である。また
、Ａｒガス流量が過大な場合は、真空槽内のスプラッシ
ュ増加による地金付着量の増大という問題も生じる。However, consuming a large amount of expensive Ar gas for a long time is extremely disadvantageous from an economic standpoint. Furthermore, if the Ar gas flow rate is excessive, there is a problem of an increase in the amount of deposited metal due to an increase in splash in the vacuum chamber.
（発明の目的）
本発明は、上記問題点を解決し、効率的かっ、経済的に
溶鋼の脱窒処理を行なうことを目的に発明されたもので
ある。(Objective of the Invention) The present invention was invented for the purpose of solving the above-mentioned problems and efficiently and economically denitrifying molten steel.
（問題解決に関する知見）
本発明者らは、還流式真空脱ガス装置において、脱ガス
処理中の溶鋼中の（Ｎ）について詳細に調査した結果、
（Ｎ）はＡρ等による脱酸の直前まで、処理時間の経過
とともに低下するが、最終脱酸の直後に吸窒を生じ、再
び上昇することを知った。そこで本発明者らは、Ａρ等
による脱酸の直前から。(Findings related to problem solving) As a result of a detailed investigation of (N) in molten steel during degassing in a reflux vacuum degassing device, the present inventors found that:
It was found that (N) decreases with the passage of treatment time until just before deoxidation by Aρ or the like, but immediately after the final deoxidation, nitrogen adsorption occurs and increases again. Therefore, the present inventors started the process immediately before deoxidizing with Aρ or the like.
溶鋼表面にＡｒガスを吹きつけることによって窒素分圧
を減少させることによって窒素濃度の上昇が抑制できる
ことを知見した。It has been found that the increase in nitrogen concentration can be suppressed by reducing the nitrogen partial pressure by blowing Ar gas onto the surface of molten steel.
（発明の構成）
本発明は溶鋼内に浸漬管を浸漬して、該溶鋼を循環する
か、もしくは吸い上げ、吐出する真空脱ガス装置におい
て、Ａｌ等による最終脱酸の直前がら、脱ガス処理終了
までの間、真空槽内の溶鋼表面に５〜１５ＮＱ／ｌｏｎ
−ｍｉｎのＡｒガスを吹き付けることを特徴とする、溶
鋼の真空精錬における窒素の低減方法を提供する。(Structure of the Invention) The present invention is a vacuum degassing device in which a dipping tube is immersed in molten steel and the molten steel is circulated or sucked up and discharged. Until then, 5 to 15 NQ/lon was applied to the surface of the molten steel in the vacuum chamber.
Provided is a method for reducing nitrogen in vacuum refining of molten steel, which is characterized by spraying Ar gas of -min.
（発明の具体的な開示）
第１図は本発明者らが、還流式真空脱ガス装置において
、脱ガス処理中の溶鋼の（Ｎ）について詳細に調査した
結果を示す、この図において明らかな通り、脱ガス処理
開始の（Ｎ）が３０ｐｐｍであったものが、ＡＩｌ等に
よる最終脱酸の直前まで、処理時間の経過と共に（Ｎ）
は低下し続け、−旦、 １５ｐｐｉ＋以下のレベルにな
ったのち、最終脱酸の直後に吸窒を生じ、再び２６ｐｐ
ｍ程度の高い（Ｎｌレベルに戻った。(Specific Disclosure of the Invention) Figure 1 shows the results of a detailed investigation by the present inventors regarding (N) in molten steel during degassing in a reflux type vacuum degassing apparatus. As expected, the (N) at the start of degassing treatment was 30 ppm, but as the treatment time progressed, (N) increased until just before the final deoxidation with AIl etc.
continued to decrease, reaching a level below 15 ppi+, and then immediately after the final deoxidation, nitrification occurred and the level dropped to 26 ppi again.
high (returned to Nl level).
このことは脱ガス処理の前半では、脱炭反応により発生
したＣＯガス気泡中への窒素吸収および還流用のＡｒガ
ス気泡中への窒素吸収による脱窒反応が促進されるが、
処理時間の経過につれ、〔ｃ〕 レベルの低下によるＣ
Ｏガス発生量の減少に伴ない、脱窒そのものが律速され
ることに加えて、ｉ等による脱酸によって界面抵抗が低
下し、かつ真空槽内の容鋼自由表面における窒素分圧が
高いために、却って、吸窒反応が進行することを示すも
のと考えられる。This means that in the first half of the degassing process, the denitrification reaction is promoted by the absorption of nitrogen into the CO gas bubbles generated by the decarburization reaction and the absorption of nitrogen into the Ar gas bubbles for reflux.
As the processing time progresses, [c] C due to a decrease in the level
As the amount of O gas generated decreases, denitrification itself is rate-limited, and interfacial resistance decreases due to deoxidation with i, etc., and the nitrogen partial pressure on the free surface of the steel in the vacuum chamber is high. On the contrary, this is considered to indicate that the nitrification reaction progresses.
そこで１本発明者らは、吸窒が認められた最終脱酸の直
前から脱ガス処理終了までの間、真空槽内の溶鋼表面に
Ａｒガスを吹き付けることにより、溶鋼自由表面におけ
る窒素分圧を下げ、低窒素濃度領域でも、脱窒反応を進
行させることを考え。Therefore, the inventors of the present invention reduced the nitrogen partial pressure on the free surface of the molten steel by spraying Ar gas onto the surface of the molten steel in the vacuum chamber from just before the final deoxidation when nitrification was observed until the end of the degassing process. The idea is to allow the denitrification reaction to proceed even in low nitrogen concentration areas.
本発明をなすにいたった。この際、 Ａｒガスの吹き付
は流量は５〜１５ＮＱ／１ｏｎ−＋１１０とすることが
肝要である。吹き付はガス流量が５ ＮＱ／ｌｏｎ・−
ｉｎより少ない場合には、溶鋼自由表面の窒素分圧の低
減効果が不十分となり、脱窒反応の進行が期待できない
。This led to the present invention. At this time, it is important that the flow rate of the Ar gas spray be 5 to 15 NQ/1on-+110. For spraying, the gas flow rate is 5 NQ/lon・-
If it is less than in, the effect of reducing the nitrogen partial pressure on the free surface of the molten steel will be insufficient, and progress of the denitrification reaction cannot be expected.
一方、吹き付はガス流量が１５Ｎρ／ｌｏｎ−ｍｉｎを
越えると、真空槽内のスプラッシュが増大し、地金付着
量の増大を招く。On the other hand, when the gas flow rate exceeds 15 Nρ/lon-min, the amount of splash in the vacuum chamber increases, leading to an increase in the amount of deposited metal.
次に本発明方法を具体的に述べる。第２図に、本発明方
法を実施するための還流式脱ガス装置概念を示す。取鍋
１内の溶鋼２は１、脱ガス処理開始と同時に、真空槽３
内に吸引される。その後、計ガス４を浸漬管５の一方に
設けたノズル６から吹き込むことにより、溶鋼２を還流
させる。この状態で、所望の〔Ｃ〕レベルまで脱炭反応
を行わせたのち、Ａｌによる最終脱酸の直前から、脱ガ
ス処理終了までの間、真空槽胴部↓こ設けられたガス吹
き付はノズル７により、ｌ０ＮＲ／ｌｏｎ−ｍｉｎ程度
のＡｒガスを溶鋼表面に吹き付けた。ガス吹き付はノズ
ルの位置は真空槽の中心軸に対して軸対象となる４箇所
とした。第３図に示すように、本発明方法によるＡｒガ
ス吹き付けにより、真空槽内の窒素分圧は著しく低減さ
れることが確認できた。第３図から明らかなように、吹
き付はガス流量が５ Ｎｎ／ｌｏｎ・ｗｉｎより少ない
場合は、真空槽内の溶鋼自由表面の窒素分圧の低減効果
は小さく、また、１５ＮＱ／ｌｏｎ・ｗｉｎより吹き付
はガス流量を増しても、窒素分圧の低減にはほとんど寄
与しないことがわかる。本性を適用した場合と適用しな
かった場合の脱ガス中の［Ｎ）の挙動を第４図に比較し
て示すが、従来脱ガス処理終了時点で２０ｐｐＩ１１以
下までは脱窒反応は進行しなかったが、本発明を適用す
ることにより、１５ｐｐｒｎ以下まで〔Ｎ）を低減する
ことが可能になった。Next, the method of the present invention will be specifically described. FIG. 2 shows the concept of a reflux type degassing device for carrying out the method of the present invention. The molten steel 2 in the ladle 1 is transferred to the vacuum chamber 3 at the same time as the degassing process starts.
sucked inside. Thereafter, the molten steel 2 is refluxed by blowing meter gas 4 through a nozzle 6 provided on one side of the immersion tube 5. In this state, after the decarburization reaction has been carried out to the desired [C] level, from just before the final deoxidation with Al until the end of the degassing process, the gas blower installed in the vacuum chamber body ↓ Ar gas of about 10NR/lon-min was sprayed onto the surface of the molten steel using the nozzle 7. For gas spraying, the nozzle positions were set at four locations symmetrical to the central axis of the vacuum chamber. As shown in FIG. 3, it was confirmed that the nitrogen partial pressure in the vacuum chamber was significantly reduced by Ar gas spraying according to the method of the present invention. As is clear from Fig. 3, when the gas flow rate is less than 5Nn/lon・win, the effect of reducing the nitrogen partial pressure on the free surface of molten steel in the vacuum chamber is small; It can be seen that even if the gas flow rate is increased, spraying hardly contributes to reducing the nitrogen partial pressure. Figure 4 shows a comparison of the behavior of [N] during degassing with and without the application of denitrification. Conventionally, the denitrification reaction does not proceed until the denitrification reaction reaches 20 ppI11 or less at the end of the degassing process. However, by applying the present invention, it became possible to reduce [N) to 15 pprn or less.
次に、本発明の実施例について述へる。実施例を表１に
要約して示す。本実施例は全て還流式脱ガス装置を用い
、溶鋼は転炉で溶製したものである。処理溶鋼量は１８
５ｔｏｎであり、脱ガス時間は２０分である。実施例１
は、Ａｌによる最終脱酸直前の、脱ガス処理開始後１５
分経過時点から５分間にわたって、２．７Ｎｒｎ’／ｗ
ｉｎ（１５ＮＱ／ｌｏｎ−ｍｉｎ）のＡｒガスを真空槽
内溶鋼面全体に吹き付けた例である。脱ガス処理前の（
Ｎ）３０ｐｐｍの溶鋼を脱ガス処理することにより、１
３ｐｐｍまで［Ｎ）を低減できた。実施例２は、脱ガス
処理開始から、２．ＯＮｍ’／ｍ１ｎ（１ＯＮＩ２／ｌ
ｏｎ−ｍｉｎ）のＡｒガスを、実施例１同様にＡｌによ
る最終脱酸直前の、脱ガス処理開始後１５分経過時点か
ら５分間にわたって、真空槽内溶鋼面全体に吹き付けた
例である。この場合には、脱ガス処理前の（Ｎ）２９ｐ
ｐｍの溶鋼を脱窒処理することにより、１５ｐｐｍまで
ＣＮ）を依減できた。この場合には、実施例１よりも脱
窒速度はやや小さく、Ａｒガス流量の影響がうががえた
。Next, examples of the present invention will be described. Examples are summarized in Table 1. In all of the examples, a reflux type degassing device was used, and the molten steel was produced in a converter. The amount of molten steel processed is 18
5 tons, and the degassing time is 20 minutes. Example 1
is 15 minutes after the start of degassing treatment, immediately before the final deoxidation with Al.
2.7Nrn'/w for 5 minutes from the time point elapsed
This is an example in which Ar gas of in (15 NQ/lon-min) was blown onto the entire surface of the molten steel in the vacuum chamber. Before degassing (
N) By degassing 30 ppm molten steel, 1
[N) could be reduced to 3 ppm. In Example 2, 2. ONm'/m1n (1ONI2/l
This is an example in which Ar gas (on-min) was sprayed onto the entire surface of the molten steel in the vacuum chamber for 5 minutes from 15 minutes after the start of the degassing process, immediately before the final deoxidation with Al, as in Example 1. In this case, (N)29p before degassing treatment
By denitrifying the molten steel with a concentration of 1.5 ppm, the CN) content could be reduced to 15 ppm. In this case, the denitrification rate was slightly lower than in Example 1, indicating the influence of the Ar gas flow rate.
比較例１は、通常処理の場合を示し、脱ガス処理前［Ｎ
］２９ｐｐｍの溶鋼を脱ガス処理しても、〔Ｎ〕は２６
ｐｐｍまでしか低減できなかった。Comparative Example 1 shows the case of normal treatment, and [N
] Even if 29 ppm molten steel is degassed, [N] is 26
It could only be reduced to ppm.
比較例２は、Ａｌによる最終脱酸後の脱ガス処理開始後
１７分経過時点から３分間にわたって、２．０Ｎｒｎ’
／ｌｌ１ｎ（１０，ＯＮＲ／ｌｏｎ−ｍｉｎ）のＡｒガ
スを、真空槽内溶鋼面全体に吹き付けた例である。この
場合には、脱ガス処理前［Ｎ］３０ｐｐｍの溶鋼を脱ガ
ス処理しても、２０ｐｐｍまでしか［Ｎ）を低減するこ
とができなかった。In Comparative Example 2, 2.0Nrn'
This is an example in which Ar gas of /ll1n (10, ONR/lon-min) was blown onto the entire surface of the molten steel in the vacuum chamber. In this case, even if molten steel containing 30 ppm [N] before degassing treatment was degassed, [N] could only be reduced to 20 ppm.
比較例３は、脱ガス処理開始からＡｌによる最終脱酸直
前までの１５分間にわたって、２．ＯＮｍ／ｍ１ｎ（１
（１，（ＪＮＲ／ｌｏｎ−ｍｉｎ）のＡｒガスを、真空
槽内溶鋼面全体に吹き付けた例である。この場合には、
脱ガス処理前（Ｎ）３１ｐｐｍの溶鋼を脱ガス処理して
も、２３ｐｐｍまでしか［Ｎ］を低減することができな
かった。In Comparative Example 3, 2. ONm/m1n(1
This is an example in which Ar gas of (1, (JNR/lon-min)) is sprayed onto the entire molten steel surface in the vacuum chamber. In this case,
Even when molten steel with a pre-degassing treatment (N) of 31 ppm was degassed, [N] could only be reduced to 23 ppm.
比較例４は、Ａｌによる最終脱酸直前の、脱ガス処理開
始後１５分経過時点から５分間にわたって、０．８Ｎｍ
／ｍ１ｎ（４，ＯＮＱ／ｌｏｎ−ｍｉｎ）のＡｒガスを
、真空槽内溶鋼全体に吹き付けた例である。この場合に
は、脱ガス処理前［Ｎ］３０ｐｐｍの溶鋼を脱ガス処理
しても、２１ｐｐｍまでしかＣＮ３を低減することがで
きなかった。In Comparative Example 4, 0.8 Nm was applied for 5 minutes from 15 minutes after the start of the degassing treatment, immediately before the final deoxidation with Al.
This is an example in which Ar gas of /m1n (4, ONQ/lon-min) was blown onto the entire molten steel in the vacuum chamber. In this case, even if molten steel containing 30 ppm [N] before degassing treatment was degassed, CN3 could only be reduced to 21 ppm.
比較例５は、Ａｌによる最終脱酸直前の脱ガス処理開始
後１５分経過時点から５分間にわたって、３．７Ｎｍ／
ｍ１ｎ（２０，ＯＮＱ／ｌｏｎ−ｍｉｎ）のＡｒガスを
、真空槽内溶鋼面全体に吹き付けた例である。この場合
には、脱ガス処理前（Ｎ）３０ｐｐｍの溶鋼を脱窒処理
することにより、１２ｐｐｍまで〔Ｎ〕を低減すること
ができたが、処理後の真空槽内に多大な地金付着が詔め
られた。In Comparative Example 5, 3.7 Nm/
This is an example in which Ar gas of m1n (20, ONQ/lon-min) was blown onto the entire surface of the molten steel in the vacuum chamber. In this case, we were able to reduce [N] to 12 ppm by denitrifying the molten steel, which had a N content of 30 ppm before degassing, but a large amount of base metal was deposited inside the vacuum chamber after the process. It was admonished.
（発明の効果）
以上述べたように、本発明による溶鋼の真空精錬におけ
る窒素の低減方法を用いることにより、２０ ｐｐｍ以
下の低窒素鋼を効率的、かつ経済的に溶製することが可
能である。(Effects of the Invention) As described above, by using the method for reducing nitrogen in vacuum refining of molten steel according to the present invention, it is possible to efficiently and economically produce low nitrogen steel of 20 ppm or less. be.
第１図は、還流式脱ガス装置における、従来法による脱
ガス処理中の溶鋼中［Ｎ）の変化を示すグラフである。
第２図は、本法を適用した際の脱ガス装置の一例を示す
図式的断面図である。
１・・・取鍋、２・・・溶鋼、３・・・真空槽、４・・
・Ａｒガス、５・・・浸漬管、６・・・ガス吹き込みノ
ズル、７・・・ガス吹き付はノズル
第３図は、真空槽内の溶鋼表面へのガス吹き付は量と、
溶鋼表面における窒素分圧の関係を示すグラフである。
第４図は、本法を適用した場合と適用しなかった場合の
（Ｎ）の変化を示すグラフである。FIG. 1 is a graph showing changes in [N] in molten steel during degassing treatment by a conventional method in a reflux type degassing device. FIG. 2 is a schematic cross-sectional view showing an example of a degassing device to which this method is applied. 1... Ladle, 2... Molten steel, 3... Vacuum chamber, 4...
・Ar gas, 5... Immersion tube, 6... Gas blowing nozzle, 7... Gas blowing nozzle. Figure 3 shows the amount of gas blowing onto the molten steel surface in the vacuum chamber,
It is a graph showing the relationship between nitrogen partial pressure on the surface of molten steel. FIG. 4 is a graph showing the change in (N) when this method is applied and when it is not applied.
Claims (1)
くは吸い上げ、吐出する真空脱ガス装置において、Ａｌ
等による最終脱酸の直前から、脱ガス処理終了までの間
、真空槽内の溶鋼表面に５〜１５Ｎｌ／ｔｏｎ・ｍｉｎ
のＡｒガスを吹き付けることを特徴とする、溶鋼の真空
精錬における窒素の低減方法。Al
From just before the final deoxidation process until the end of the degassing process, 5 to 15 Nl/ton/min is applied to the surface of the molten steel in the vacuum chamber.
A method for reducing nitrogen in vacuum refining of molten steel, the method comprising spraying Ar gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2172388A JP3071445B2 (en) | 1990-06-29 | 1990-06-29 | Methods for reducing nitrogen in vacuum refining of molten steel. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2172388A JP3071445B2 (en) | 1990-06-29 | 1990-06-29 | Methods for reducing nitrogen in vacuum refining of molten steel. |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0463221A true JPH0463221A (en) | 1992-02-28 |
| JP3071445B2 JP3071445B2 (en) | 2000-07-31 |
Family
ID=15941003
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2172388A Expired - Fee Related JP3071445B2 (en) | 1990-06-29 | 1990-06-29 | Methods for reducing nitrogen in vacuum refining of molten steel. |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3071445B2 (en) |
-
1990
- 1990-06-29 JP JP2172388A patent/JP3071445B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP3071445B2 (en) | 2000-07-31 |
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