JPH03271315A - Rh vacuum decarbonizing method for stainless steel - Google Patents
Rh vacuum decarbonizing method for stainless steelInfo
- Publication number
- JPH03271315A JPH03271315A JP7258490A JP7258490A JPH03271315A JP H03271315 A JPH03271315 A JP H03271315A JP 7258490 A JP7258490 A JP 7258490A JP 7258490 A JP7258490 A JP 7258490A JP H03271315 A JPH03271315 A JP H03271315A
- Authority
- JP
- Japan
- Prior art keywords
- decarburization
- oxygen
- stainless steel
- molten
- vacuum
- 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.)
- Pending
Links
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 17
- 239000010935 stainless steel Substances 0.000 title claims abstract description 17
- 238000000034 method Methods 0.000 title claims description 16
- 239000001301 oxygen Substances 0.000 claims abstract description 64
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 64
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 63
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 27
- 239000010959 steel Substances 0.000 claims abstract description 27
- 238000009849 vacuum degassing Methods 0.000 claims abstract description 20
- 238000007664 blowing Methods 0.000 claims abstract description 10
- 238000005261 decarburization Methods 0.000 claims description 80
- 230000000694 effects Effects 0.000 claims description 20
- 238000002347 injection Methods 0.000 claims description 16
- 239000007924 injection Substances 0.000 claims description 16
- 239000007789 gas Substances 0.000 claims description 12
- 238000007872 degassing Methods 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 abstract description 9
- 230000003647 oxidation Effects 0.000 abstract description 4
- 238000007254 oxidation reaction Methods 0.000 abstract description 4
- 238000007670 refining Methods 0.000 abstract 4
- 238000005262 decarbonization Methods 0.000 abstract 3
- 239000002994 raw material Substances 0.000 abstract 2
- 239000001257 hydrogen Substances 0.000 abstract 1
- 229910052739 hydrogen Inorganic materials 0.000 abstract 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 abstract 1
- 239000011261 inert gas Substances 0.000 abstract 1
- 230000000452 restraining effect Effects 0.000 abstract 1
- 239000002893 slag Substances 0.000 abstract 1
- 229910052799 carbon Inorganic materials 0.000 description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 229910001021 Ferroalloy Inorganic materials 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000004907 flux Effects 0.000 description 3
- 238000009489 vacuum treatment Methods 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 210000002758 humerus Anatomy 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、ＲＨ真空脱ガス法に基づくステンレス溶鋼の
真空脱ガス槽内において、脱ガスとともに脱炭処理する
際の脱炭方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a decarburization method for performing decarburization along with degassing in a vacuum degassing tank for molten stainless steel based on the RH vacuum degassing method.
ＲＨ真空脱ガス法による真空脱ガス処理は、溶鋼中の水
素ガス等の脱ガスが主目的であるが、真空脱ガス中の溶
鋼へその温度低下を防止するために、酸素を吹き込みつ
つ脱炭処理を行う方法（例えば、特公昭６０−４３４０
８号）も有効であることが知られている。この真空脱ガ
ス法は転炉等により脱炭すると鉄粉の酸化が多く鉄歩留
りが低下するため、−旦転炉等により脱炭した溶鋼を真
空処理槽内で最終目標値まで脱炭し、鉄粉の酸化を抑え
鉄歩留りを向上させることを狙いとしている。The main purpose of vacuum degassing treatment using the RH vacuum degassing method is to degas hydrogen gas etc. from molten steel, but in order to prevent the temperature of molten steel from decreasing during vacuum degassing, decarburization is performed while blowing oxygen into the molten steel. Processing method (for example, Japanese Patent Publication No. 60-4340
No. 8) is also known to be effective. In this vacuum degassing method, decarburizing in a converter etc. causes a lot of oxidation of the iron powder and lowers the iron yield. The aim is to suppress oxidation of iron powder and improve iron yield.
前記公報記載の具体的方法は、真空処理前の溶鋼炭素量
、温度および溶鋼の目標終点炭素量、温度を入力値とし
、脱炭効率、昇温効率を用い、必要な酸素量と冷却剤ま
たは昇温剤を算出して真空処理する方法である。The specific method described in the above publication uses the molten steel carbon content and temperature before vacuum treatment, the target end point carbon content of molten steel, and temperature as input values, uses the decarburization efficiency and temperature increase efficiency, and calculates the required oxygen content and coolant or This method calculates the temperature increasing agent and performs vacuum treatment.
この方法によれば、真空脱ガス処理時に脱炭反応を起こ
すため脱炭反応熱により溶鋼温度の低下が防止され、長
時間の真空脱ガスが可能となり、溶鋼中のガス量の低減
が可能となるという利点がある。According to this method, since a decarburization reaction occurs during vacuum degassing treatment, the heat of the decarburization reaction prevents the temperature of the molten steel from decreasing, allowing long-term vacuum degassing and reducing the amount of gas in the molten steel. It has the advantage of being
また、本出願人は、特開昭６２−１７４３１７号におい
て、酸素センサーを用いて、溶鋼中酸素量を測定し、こ
の溶鋼中の酸素量に基づいて脱炭反応を制御することを
提案した。さらに、特開平１−２２２０１８号において
は、測定したＣＯガスの濃度と溶鋼中炭素量との相関に
基づいて脱炭反応を制御することも提案した。In addition, the present applicant proposed in JP-A-62-174317 to measure the amount of oxygen in molten steel using an oxygen sensor and to control the decarburization reaction based on the amount of oxygen in the molten steel. Furthermore, in JP-A-1-222018, it was also proposed to control the decarburization reaction based on the correlation between the measured concentration of CO gas and the amount of carbon in molten steel.
しかし、これら各先行法の何れも、酸素吹込みをある時
間まで連続的に行い、その後自己脱炭を行う単純な方法
である。However, each of these prior methods is a simple method in which oxygen is continuously blown for a certain period of time and then self-decarburization is performed.
しかしながら、上記従来法では次のような問題点があっ
た。However, the above conventional method has the following problems.
■ 脱炭速度が遅く、脱炭に要する時間が長いために、
ＲＨ槽の下部槽および浸漬管寿命を著しく悪化する。■ Because the decarburization rate is slow and the time required for decarburization is long,
This will significantly shorten the life of the lower tank of the RH tank and the immersion tube.
■ 脱炭所要時間が長いため、脱炭中の成分ロスが大き
い。このために、（ａｌ投入合金鉄原単位の悪化を招く
、（ｂ）脱炭後に合金鉄を多量添加せねばならず、［Ｃ
］ピックアップの要因となる、等の弊害が出てくる。■ Because decarburization takes a long time, component loss during decarburization is large. For this reason, (b) it is necessary to add a large amount of ferroalloy after decarburization, (causing deterioration of the Al input ferroalloy unit consumption,
] This may cause problems such as pickup.
そこで本発明の主たる目的は、脱炭速度を向上し、また
脱炭中の成分ロスを極力抑えることのできるステンレス
鋼のＲＨ真空脱炭方法を提供することにある。Therefore, the main object of the present invention is to provide an RH vacuum decarburization method for stainless steel, which can improve the decarburization rate and minimize component loss during decarburization.
上記課題は、ステンレス溶鋼をＲＨ真空脱ガス槽で真空
脱炭するに当たり、脱炭処理に供するステンレス溶鋼中
の［Ｓｉ３を０．３５％以下とし、かっ脱炭処理におい
て、［Ｏ］の活量と前記脱ガス槽からの排ガス中のＣＯ
濃度とに基づいて、酸素吹込みによる脱炭および酸素吹
込みを行わない自己脱炭とを繰り返しなから脱炭処理を
行い、かつその酸素吹込み時の送酸速度を４００〜８０
ＯＮ１７Ｈとすることで解決できる。The above problem is that when vacuum decarburizing stainless steel molten steel in an RH vacuum degassing tank, the [Si3 content in the stainless steel molten steel subjected to decarburization treatment is set to 0.35% or less, and the activity of [O] in the decarburization treatment is and CO in the exhaust gas from the degassing tank
Based on the concentration, the decarburization treatment is performed by repeating decarburization by oxygen injection and self-decarburization without oxygen injection, and the oxygen feeding rate during the oxygen injection is set to 400 to 80.
This can be solved by setting it to ON17H.
本発明では、脱炭処理に供するステンレス溶鋼中の［Ｓ
ｉ３を０．３５％以下としである。したがって、脱炭効
率が高い。また、従来のように、酸素吹込みによる脱炭
および酸素吹込みを行わない自己脱炭とを単に所望の炭
素量になるよう一回のみ行うのでなく、それらの操作を
繰り返すので、脱炭速度が著しく速まる。さらに、送酸
速度を４００〜８０ ＯＮｍ３／Ｈとしているので、送
酸羽口での詰まりがなく、かつ成分ロスが少なくなる。In the present invention, [S] in molten stainless steel subjected to decarburization treatment is
i3 is set to 0.35% or less. Therefore, decarburization efficiency is high. In addition, unlike conventional methods, decarburization by oxygen injection and self-decarburization without oxygen injection are performed only once to reach the desired carbon content, but these operations are repeated, resulting in faster decarburization. speeds up significantly. Furthermore, since the oxygen feeding rate is set to 400 to 80 ONm3/H, there is no clogging at the oxygen feeding tuyere, and component loss is reduced.
しかも、送酸開始時点をＣＯ濃度に基づいて、自己脱炭
開始時点を［Ｏ］の活量に基づいてそれぞれ定めるので
、速やかな脱炭を行うことができる。Moreover, since the time point at which oxygen supply starts is determined based on the CO concentration and the time point at which self-decarburization starts is determined based on the activity of [O], prompt decarburization can be performed.
以下本発明をさらに詳説する。 The present invention will be explained in more detail below.
周知のように、真空脱ガス槽内における炭素と酸素との
反応は、（１）式または（２）式で表される。As is well known, the reaction between carbon and oxygen in a vacuum degassing tank is expressed by equation (1) or equation (2).
ｃ＋−Ｑ−→ＣＯ・・・ （１）
Ｃ＋２．、Ｑ−→ＣＯ２・・・ （２）したがって、真
空脱ガス槽のガス、たとえば排ガス中のＣＯおよびまた
はＣＯを濃度を測定すれば、脱炭反応の進行状況を把握
することができ、もって溶鋼中の炭素量を予測し制御す
ることが可能となる。ちなみに、種々の溶鋼について、
排ガス中のＣＯ濃度と溶鋼中の炭素濃度との相関につい
て調べたところ、第３図のように、強い相関が認められ
、バラツキσとして０．０００３程度であり、特開平１
−２２２０１８公報で述べたように、ＣＯの濃度の測定
結果に基づいて脱炭反応の進行状況を判断することが有
効である。ことが判る。c+-Q-→CO... (1) C+2. , Q-→CO2... (2) Therefore, by measuring the concentration of CO and/or CO in the gas in the vacuum degassing tank, for example, the exhaust gas, it is possible to grasp the progress of the decarburization reaction, thereby reducing the amount of molten steel. It becomes possible to predict and control the amount of carbon inside. By the way, regarding various types of molten steel,
When we investigated the correlation between the CO concentration in exhaust gas and the carbon concentration in molten steel, we found a strong correlation as shown in Figure 3, and the variation σ was about 0.0003, which is the same as that of JP-A-1
As stated in Publication No. 222018, it is effective to judge the progress of the decarburization reaction based on the measurement result of the concentration of CO. I understand that.
一方、本発明者は、ステンレス溶鋼をＲＨ真空脱ガス槽
で真空脱炭するに当たり、脱炭処理に供するステンレス
溶鋼中の［Ｓｉ″Ｊによって、脱炭速度が異なり、［Ｓ
ｉ３が０．３５％以下であると充分満足できる脱炭速度
が得られることを知見した。たとえば、第４図のように
、脱炭時間と［Ｃ］との相関を、ＲＨ真空脱ガス処理前
の［Ｓ ｉ］を変えて調べたところ、［Ｓｉ３が低い方
が、脱炭速度が大きいことが判る。また、第５図には、
還流量を変えながら、ＲＨ真空処理前の［Ｓｉ３と脱炭
速度との関係を示した。この図からも［Ｓｉ３の低い方
が脱炭速度が大きいことが判る。ただし、脱炭速度は、
（３）式に従うと仮定した。On the other hand, the present inventor discovered that when vacuum decarburizing stainless steel molten steel in an RH vacuum degassing tank, the decarburization rate differs depending on [Si''J in the stainless steel molten steel subjected to decarburization treatment, and [S
It has been found that a fully satisfactory decarburization rate can be obtained when i3 is 0.35% or less. For example, as shown in Figure 4, when we investigated the correlation between decarburization time and [C] by changing [Si] before the RH vacuum degassing treatment, we found that the decarburization rate was lower when [Si3 was lower]. It turns out it's big. Also, in Figure 5,
The relationship between [Si3 before RH vacuum treatment and decarburization rate was shown while changing the reflux amount. This figure also shows that the lower the Si3 content, the higher the decarburization rate. However, the decarburization rate is
It is assumed that equation (3) is followed.
Δ［Ｃ］／Δｔ＝Ｋｃ （［Ｃ］ −［Ｃ］ ｅ） ＝
・（３）ここに、Ｋｃ；脱炭速度定数、［Ｃ］；Ｃ濃度
、［Ｃ］ｅ；平衡Ｃ濃度である。Δ[C]/Δt=Kc ([C] − [C] e) =
-(3) Here, Kc: decarburization rate constant, [C]: C concentration, [C]e: equilibrium C concentration.
さらに、脱炭処理に供するステンレス溶鋼中の［Ｓｉ］
が０．３５％を超えると、脱炭速度が遅いので、当然に
Ｓｉ、Ｍｎ、Ｃｒなどの成分ロスが多くなることも実験
により確認している。Furthermore, [Si] in molten stainless steel subjected to decarburization treatment
It has also been confirmed through experiments that when the amount exceeds 0.35%, the decarburization rate is slow, and as a result, the loss of components such as Si, Mn, and Cr naturally increases.
次に、脱炭中の酸素活量ａ０と炭素濃度との関係は、た
とえば第６図のように、脱炭限界は酸素活量ａ０ととも
にＣＯガスの分圧Ｐｃｏによって変化する。したがって
、逆に酸素活量ａ０とともにＣＯガスの分圧ＰＣＯを測
定することにより、脱炭状況を管理することが重要であ
ることが判る。ちなみに、例えば、ＣＯガスの分圧Ｐｃ
ｏ＝ １．５ ｔｏｒｒと仮定すると、脱炭の目標値と
して平衡［％Ｃ］≦０．０１にするには、ａＯ≧１５ｐ
ｐｍにしなければならない。また、真空度を高めること
によりＣＯガスの分圧Ｐ。０を低下させることが望まし
いことも判る。Next, regarding the relationship between the oxygen activity a0 and the carbon concentration during decarburization, for example, as shown in FIG. 6, the decarburization limit changes depending on the oxygen activity a0 and the partial pressure Pco of CO gas. Therefore, it can be seen that it is important to manage the decarburization situation by measuring the partial pressure PCO of CO gas as well as the oxygen activity a0. By the way, for example, the partial pressure Pc of CO gas
Assuming o=1.5 torr, in order to achieve equilibrium [%C]≦0.01 as the target value for decarburization, aO≧15p
It has to be pm. In addition, by increasing the degree of vacuum, the partial pressure P of CO gas can be reduced. It can also be seen that it is desirable to lower 0.
さらに、第７図に、［％Ｓｉ］と酸素活量ａ０との関係
例を示した。これは、［Ｓ ｉ］ −［Ｏ］平衡より求
めたもので、たとえば、ａ０≧１５ｐｐｍにするには［
％Ｓｉ］≦０．２８にしなければならない。かかる関係
が得られる理由は、［％Ｓｉｌが低い程、脱炭限界の［
Ｃ］ （平衡［Ｃ］）が低下するため、脱炭速度が速い
ためであると考えられる。Furthermore, FIG. 7 shows an example of the relationship between [%Si] and oxygen activity a0. This is obtained from the [S i] - [O] equilibrium. For example, to make a0≧15ppm, [
%Si]≦0.28. The reason why such a relationship is obtained is that the lower [%Sil is, the lower the decarburization limit [
This is thought to be because the decarburization rate is fast because the equilibrium [C] (equilibrium [C]) is lowered.
本発明においては、酸素吹込みによる脱炭および酸素吹
込みを行わない自己脱炭とを繰り返しながら脱炭処理を
行う。In the present invention, decarburization is performed by repeating decarburization by oxygen injection and self-decarburization without oxygen injection.
この目的は、脱炭速度を速めるとともに、脱炭時の成分
ロス（Ｍｎ、Ｃｒ、Ｓ ｉなどのロス）を極力低減する
ためである。The purpose of this is to increase the decarburization speed and to reduce component loss (loss of Mn, Cr, Si, etc.) during decarburization as much as possible.
第８図はＭｎロスと脱炭プロセスとの関係を示す図であ
り、脱炭プロセスは第２図に示した通りである。このよ
うに、酸素吹込み（ＯＢ）と、自己脱炭との繰り返しに
より、酸素活量ａ０をコントロールすることにより、Ｍ
ｎの酸化ロスは低減することが判る。しかし、ヒユーム
ロスのために時間対応して一次的なＭｎロスは避けるこ
とができない。この第８図からも、酸素吹込みによる脱
炭および酸素吹込みを行わない自己脱炭とを繰り返すこ
とが有効であることが判る。FIG. 8 is a diagram showing the relationship between Mn loss and the decarburization process, and the decarburization process is as shown in FIG. 2. In this way, by controlling the oxygen activity a0 by repeating oxygen blowing (OB) and self-decarburization, M
It can be seen that the oxidation loss of n is reduced. However, temporal Mn loss cannot be avoided due to humerus loss. It can also be seen from FIG. 8 that it is effective to repeat decarburization by oxygen injection and self-decarburization without oxygen injection.
酸素吹込み時における送酸速度も、成分ロスに大きな影
響を与える。たとえば、Ｃｒロスについては、第９図に
示すように、送酸速度を８０ＯＮｍ３／Ｈとするととも
に連続送酸を行う（連続送酸段階以降は自己脱炭のみ）
とＣｒロスが大きいのに対して、本発明にしかって例え
ば送酸速度たとえば６０ ＯＮｍ３／Ｈとして低くし、
かつ酸素活量ａ０の管理を行いつつ送酸と自己脱炭とを
繰り返すことにより、Ｃｒロスはほぼ無いことが判明し
た。なお、酸素活量ａ０は１５〜２０ｐｐｍの範囲で管
理した。一方、送酸と自己脱炭とを繰り返すとしても、
送酸速度が８０ ＯＮｍ’／Ｈを超えると、成分ロスが
多く、また送酸速度４０ ＯＮｍ３／Ｈ未満であると、
送酸羽口が詰まり、送酸を行うことができない現象が見
られる。The oxygen delivery rate during oxygen injection also has a large effect on component loss. For example, regarding Cr loss, as shown in Figure 9, the oxygen supply rate is set to 80ONm3/H and continuous oxygen supply is performed (only self-decarburization is performed after the continuous oxygen supply stage).
In contrast, in the present invention, the oxygen delivery rate is lowered, for example, to 60 ONm3/H, and the Cr loss is large.
It was also found that by repeating oxygen supply and self-decarburization while controlling the oxygen activity a0, there was almost no Cr loss. Note that the oxygen activity a0 was controlled within a range of 15 to 20 ppm. On the other hand, even if oxygen supply and self-decarburization are repeated,
If the oxygen delivery rate exceeds 80 ONm'/H, there will be a lot of component loss, and if the oxygen delivery rate is less than 40 ONm3/H,
There is a phenomenon in which the oxygen supply tuyere is clogged and oxygen cannot be supplied.
Ｓｉロスについては、前述した第７図に示すように、た
とえば、［Ｃ］≦ｏ、 ｏ ｉ ｏ％に対応する脱炭処
理前の［％Ｓｉ］ レベルは０．２８％程度と考えられ
る。第１Ｏ図より、脱炭処理前の［％Ｓｉ］＞０．３５
では、Ｓｉロスは脱炭不良のため増加し、これに対して
たとえば処理前のＳｉ濃度が［％Ｓｉ］≦０．２９では
、０．０３％以下のＳｉロスに抑制することができる。Regarding Si loss, as shown in FIG. 7 described above, for example, the [%Si] level before decarburization corresponding to [C]≦o, o io% is considered to be about 0.28%. From Figure 1O, [%Si] > 0.35 before decarburization treatment
In this case, the Si loss increases due to poor decarburization, but on the other hand, if the Si concentration before treatment is [%Si]≦0.29, the Si loss can be suppressed to 0.03% or less.
本発明は、たとえば、第１図に示す態様のＲＨ真空脱ガ
ス設備において実施される。The present invention is implemented, for example, in an RH vacuum degassing facility of the embodiment shown in FIG.
すなわち、溶鋼ｌを収容する取鍋２上に、ＲＨ真空脱ガ
ス槽３が配され、その下部に付属する上昇管３ａおよび
下降管３ｂを介して溶鋼ｌが循環するようになっている
。脱ガス槽３は、排気路４を介して図示しない真空装置
に連なっている。上昇管３ａには環流ガス吹込羽口５が
形成されている。６は酸素Ａの吹込羽口、７は合金投入
口、８は酸素濃度検出器である。That is, the RH vacuum degassing tank 3 is disposed on the ladle 2 that accommodates the molten steel 1, and the molten steel 1 is circulated through an ascending pipe 3a and a descending pipe 3b attached to the lower part thereof. The degassing tank 3 is connected to a vacuum device (not shown) via an exhaust path 4. A recirculation gas blowing tuyere 5 is formed in the riser pipe 3a. 6 is a tuyere for blowing oxygen A, 7 is an alloy inlet, and 8 is an oxygen concentration detector.
また排気路４にはＣＯ濃度検出器９が設けられるととも
に、それからの信号および酸素濃度検出器８からの信号
を受けて演算処理する演算装置１０も用意されている。Further, the exhaust path 4 is provided with a CO concentration detector 9, and is also provided with an arithmetic unit 10 that receives signals from the CO concentration detector 9 and signals from the oxygen concentration detector 8 and performs arithmetic processing.
操業の具体例としては、まず、真空脱ガス槽３中を所定
の真空度に保持するとともに、フラックスを投入する。As a specific example of the operation, first, the interior of the vacuum degassing tank 3 is maintained at a predetermined degree of vacuum, and flux is introduced.
また、還流を開始する。次いで、送酸を大流量たとえば
１２０ ＯＮｍ３／Ｈをもって溶鋼の昇温を行う。続い
て、本発明の主要点としての、酸素吹込み（ＯＢ）およ
び自己脱炭を繰り返す。たとえば６０ ＯＮｍ３／Ｈで
送酸し、ＣＯ濃度検出器９からのＣＯ濃度が１０％以下
となったとき、自己脱炭に切り替え、自己脱炭を行って
いる過程で、酸素濃度検出器８からの酸素濃度に基づく
活量ａ０が１５ｐｐ０１になった時、再び送酸する。以
上の行程を目標とする［Ｃ］たとえば０．０１０％まで
脱炭するまで反復する。Also, start refluxing. Next, the temperature of the molten steel is raised by supplying oxygen at a large flow rate, for example, 120 ONm3/H. Subsequently, oxygen blowing (OB) and self-decarburization, which are the main points of the present invention, are repeated. For example, when oxygen is supplied at 60 ONm3/H and the CO concentration from the CO concentration detector 9 becomes 10% or less, it switches to self-decarburization, and during the self-decarburization process, the CO concentration from the oxygen concentration detector 8 When the activity a0 based on the oxygen concentration reaches 15pp01, oxygen is sent again. The above steps are repeated until the target [C] is decarburized to, for example, 0.010%.
かかる脱炭が終了したならば、脱ガス槽３の真空吸引を
停止し、復圧させてＡｊ７を投入し、その後合金鉄の投
入、送酸による昇温、フラックスの投入、ＡＩ量の調整
用フラックスの投入など適宜の操作を行う。When such decarburization is completed, the vacuum suction of the degassing tank 3 is stopped, the pressure is restored and Aj7 is introduced, and then the ferroalloy is introduced, the temperature is increased by oxygen supply, the flux is introduced, and the amount of AI is adjusted. Perform appropriate operations such as adding flux.
なお、酸素吹込みから自己脱炭への切り替えは、前記例
のように、ＣＯ濃度が１０％とするほか、ＣＯ濃度が１
〜４０％の範囲内の適宜の濃度で行うことができ、他方
、自己脱炭から酸素吹込みへの切り替えは、活量ａ０が
前記例のように１５ｐｐｍとするほか、７〜３５ｐｐａ
＋の範囲内の適宜の値を設定して行うことができる。他
方、酸素吹込みから自己脱炭への切り替え時点の管理を
、ｃｏ濃度によることに代えて、活量ａ０を基準とする
こともでき、たとえば活量ａ、：１５ｐｐｍを基準とし
て管理することができる。Note that switching from oxygen injection to self-decarburization is performed when the CO concentration is 10% as in the above example, and when the CO concentration is 10%.
On the other hand, switching from self-decarburization to oxygen injection can be carried out at an appropriate concentration within the range of ~40%, while the activity a0 is set at 15 ppm as in the above example, or at a concentration of 7 to 35 ppa.
This can be done by setting an appropriate value within the + range. On the other hand, the timing of switching from oxygen injection to self-decarburization can be managed based on the activity a0 instead of based on the CO concentration. For example, the control can be based on the activity a: 15 ppm. can.
一方、酸素吹込みから自己脱炭への切り替えまたはその
逆の切り替えにあたり、本来なら活量ａ０で管理するの
が好ましいけれども、活量ａ０を直接測定するには、計
測器のコスト高となる、溶鋼中の活量ａ０を充分ＣＯ濃
度で推定できる、ｃ。On the other hand, when switching from oxygen injection to self-decarburization or vice versa, it is preferable to manage the activity using the activity a0, but directly measuring the activity a0 requires high cost of measuring equipment. The activity a0 in molten steel can be estimated sufficiently from the CO concentration, c.
濃度の測定によると連続測定が可能となるなどの観点か
ら、現実にはＣＯ濃度の測定によるのが好ましい。In reality, it is preferable to measure the CO concentration because measuring the concentration allows continuous measurement.
なお、上記各実験においては、オーステナイトステンレ
ス（低Ｃ材）：ＷＳＴ４ＬＳＷＣ３Ｔ４またはＷＲ３Ｔ
ＪＬ系のものを用いた。In each of the above experiments, austenitic stainless steel (low C material): WST4LSWC3T4 or WR3T
A JL type one was used.
以上の通り、本発明によれば、脱炭速度を速めることか
できるとともに、また脱炭中の成分ロスを極力抑えるこ
とのできるなどの利点がもたらされる。As described above, according to the present invention, the decarburization speed can be increased, and the loss of components during decarburization can be suppressed as much as possible.
第１図は本発明法を実施するための設備例の概要図、第
２図は操業例の説明図、第３図〜第１０図は実験結果の
グラフである。
２・・・取鍋、３・・・真空脱ガス槽、８・・−酸素濃
度検出器、９・・・ＣＯ濃度検出器。
第１図FIG. 1 is a schematic diagram of an example of equipment for implementing the method of the present invention, FIG. 2 is an explanatory diagram of an example of operation, and FIGS. 3 to 10 are graphs of experimental results. 2... Ladle, 3... Vacuum degassing tank, 8...-Oxygen concentration detector, 9... CO concentration detector. Figure 1
Claims (1)
るに当たり、脱炭処理に供するステンレス溶鋼中の［Ｓ
ｉ］を０．３５％以下とし、かつ脱炭処理において、［
Ｏ］の活量と前記脱ガス槽からの排ガス中のＣＯ濃度と
に基づいて、酸素吹込みによる脱炭および酸素吹込みを
行わない自己脱炭とを繰り返しながら脱炭処理を行い、
かつその酸素吹込み時の送酸速度を４００〜８００Ｎｍ
＾３／Ｈとすることを特徴とするステンレス鋼のＲＨ真
空脱炭方法。(1) When vacuum decarburizing stainless steel molten steel in an RH vacuum degassing tank, [S] in the stainless steel molten steel subjected to decarburization treatment is
i] is 0.35% or less, and in the decarburization treatment, [
Based on the activity of [O] and the CO concentration in the exhaust gas from the degassing tank, decarburization is performed while repeating decarburization by oxygen injection and self-decarburization without oxygen injection,
And the oxygen supply rate during oxygen blowing is 400 to 800Nm.
An RH vacuum decarburization method for stainless steel characterized by ^3/H.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7258490A JPH03271315A (en) | 1990-03-22 | 1990-03-22 | Rh vacuum decarbonizing method for stainless steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7258490A JPH03271315A (en) | 1990-03-22 | 1990-03-22 | Rh vacuum decarbonizing method for stainless steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03271315A true JPH03271315A (en) | 1991-12-03 |
Family
ID=13493574
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7258490A Pending JPH03271315A (en) | 1990-03-22 | 1990-03-22 | Rh vacuum decarbonizing method for stainless steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03271315A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011023337A1 (en) | 2009-08-28 | 2011-03-03 | Sms Siemag Aktiengesellschaft | Device for degassing molten steel with an improved discharge nozzle |
-
1990
- 1990-03-22 JP JP7258490A patent/JPH03271315A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011023337A1 (en) | 2009-08-28 | 2011-03-03 | Sms Siemag Aktiengesellschaft | Device for degassing molten steel with an improved discharge nozzle |
| DE102009039260A1 (en) | 2009-08-28 | 2011-03-03 | Sms Siemag Ag | Apparatus for degassing a molten steel with an improved spout |
| US9181602B2 (en) | 2009-08-28 | 2015-11-10 | Sms Group Gmbh | Device for degassing molten steel with an improved discharge nozzle |
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