JPH05287360A - Method for melting extremely low carbon steel - Google Patents
Method for melting extremely low carbon steelInfo
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- JPH05287360A JPH05287360A JP8375892A JP8375892A JPH05287360A JP H05287360 A JPH05287360 A JP H05287360A JP 8375892 A JP8375892 A JP 8375892A JP 8375892 A JP8375892 A JP 8375892A JP H05287360 A JPH05287360 A JP H05287360A
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- molten steel
- gas
- mass
- decarburization
- concentration
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- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、溶鋼の真空脱ガス装置
において、溶鋼中の炭素（以下、［Ｃ］と記す）の含有
量を極微量、例えば、０．００１ｍａｓｓ％以下まで除
去し、極低炭素鋼を溶製するための効率的かつ経済的な
極低炭素鋼の溶製方法に関するものである。FIELD OF THE INVENTION The present invention relates to a vacuum degassing apparatus for molten steel, in which the content of carbon (hereinafter referred to as [C]) in the molten steel is removed to an extremely small amount, for example, 0.001 mass% or less, The present invention relates to an efficient and economical melting method for extremely low carbon steel for melting extremely low carbon steel.
【０００２】[0002]
【従来の技術】一般に、製鉄業においては、溶鋼の脱炭
処理を、例えば第３版鉄鋼便覧ＩＩ製銑・製鋼６７１〜
６８５ページに示されているような減圧脱炭装置を用い
て実施している。しかし、［Ｃ］濃度が０．００５ｍａ
ｓｓ％以下になると脱炭速度が急激に低下し、［Ｃ］含
有量を極微量まで迅速に低減することは容易でない。
［Ｃ］濃度が０．００５ｍａｓｓ％以下では、溶鋼内部
からのＣＯ気泡の発生を伴う脱炭反応が少なくなり、溶
鋼自由表面あるいは、吹込まれたＡｒ気泡と溶鋼との界
面における脱炭反応が主体となると言われている。した
がって、［Ｃ］濃度が０．００５ｍａｓｓ％以下の領域
において、気・液反応界面積を増大させて脱炭反応を促
進させる方策がとられる。2. Description of the Related Art Generally, in the steel industry, decarburization treatment of molten steel is carried out, for example, in the Iron and Steel Making 671-
It is carried out using a vacuum decarburizer as shown on page 685. However, the [C] concentration is 0.005 ma
When it is ss% or less, the decarburization rate sharply decreases, and it is not easy to rapidly reduce the [C] content to an extremely small amount.
When the concentration of [C] is 0.005 mass% or less, the decarburization reaction accompanied by the generation of CO bubbles from the inside of the molten steel decreases, and the decarburization reaction mainly occurs on the molten steel free surface or the interface between the blown Ar bubbles and the molten steel. It is said that Therefore, in the region where the [C] concentration is 0.005 mass% or less, a measure is taken to increase the gas-liquid reaction interface area to accelerate the decarburization reaction.
【０００３】例えば、ＲＨ真空脱ガス装置において、
［Ｃ］濃度が０．０１ｍａｓｓ％以下の領域で気・液反
応界面積の増大と溶鋼強攪拌をねらってＨ2 ガス、Ｈ2
＋Ａｒガス、アンモニアガスなどの水素含有物質を溶鋼
中に吹込み、水素ガスボイリングをおこなわせることに
より脱炭反応を促進する方法が特公昭６０−２１２０７
号公報に開示されている。For example, in an RH vacuum degasser,
H 2 gas, H 2 in order to increase the gas-liquid reaction interface area and to strongly stir molten steel in the region where the concentration of [C] is 0.01 mass% or less
A method of accelerating the decarburization reaction by injecting a hydrogen-containing substance such as + Ar gas or ammonia gas into molten steel and performing hydrogen gas boiling is disclosed in Japanese Examined Patent Publication No. Sho 60-21207.
It is disclosed in the publication.
【０００４】[0004]
【発明が解決しようとする課題】この方法の場合、水素
含有ガスを溶鋼中に吹込む際、ガスを吹込むためのポー
ラスレンガや浸漬ランスの異常溶損のため安定して溶鋼
にガスを吹込むことは困難である。さらに、水素を一旦
溶鋼中に溶解させるため、脱炭処理の後に溶鋼から水素
を除去する工程が必要である。このため、処理時間が長
くなり、経済的には不利である。In the case of this method, when the hydrogen-containing gas is blown into the molten steel, it is possible to stably blow the gas into the molten steel due to abnormal melting damage of the porous brick or the immersion lance for blowing the gas. It is difficult. Further, since hydrogen is once dissolved in the molten steel, a step of removing hydrogen from the molten steel is required after the decarburization treatment. Therefore, the processing time becomes long, which is economically disadvantageous.
【０００５】[0005]
【課題を解決するための手段】本発明は上記課題を解決
するため、減圧下において、溶鋼の脱炭処理を実施する
にあたり、溶鋼中の炭素濃度が０．０２０ｍａｓｓ％以
下の領域で、真空槽内の溶鋼に、Ｃａ（ＯＨ）2 ，Ｍｇ
（ＯＨ）2 ，Ｆｅ（ＯＨ）2 の一種もしくは二種以上の
混合物を溶鋼１トンあたりに毎分０．７５モル以上、
７．５モル以下の添加速度で添加することを特徴とする
極低炭素鋼の溶製方法、を提供するものである。In order to solve the above problems, the present invention provides a vacuum tank in which carbon concentration in molten steel is 0.020 mass% or less when decarburizing molten steel under reduced pressure. The molten steel inside contains Ca (OH) 2 , Mg
One or a mixture of two or more of (OH) 2 and Fe (OH) 2 is added in an amount of 0.75 mol / min or more per ton of molten steel,
The present invention provides a method for smelting ultra-low carbon steel, which is characterized by adding at an addition rate of 7.5 mol or less.
【０００６】[0006]
【作用】以下、本発明について詳細に述べる。本発明の
本質は、ガス成分を含有する固体物質を溶鋼に添加した
ときに瞬間的に分解して発生するガスによって、気・液
反応界面積を増大させることにある。The present invention will be described in detail below. The essence of the present invention is to increase the gas-liquid reaction interface area by the gas generated by momentary decomposition when a solid substance containing a gas component is added to molten steel.
【０００７】一般に、減圧下での溶鋼の脱炭反応は、大
きくつぎの３種類に分類される。すなわち、 溶鋼内部、耐火物表面で［Ｃ］と酸素（以下、［Ｏ］
と記す）との反応、この場合はＣＯ気泡の発生を伴う。 減圧雰囲気にさらされている溶鋼自由表面での、
［Ｃ］と［Ｏ］との反応。 溶鋼中に吹込まれたアルゴン気泡と溶鋼との界面で起
こる［Ｃ］と［Ｏ］との反応。 とに分類される。これらの反応の内、［Ｃ］濃度が０．
０２０ｍａｓｓ％超の領域ではの反応が主体であるこ
とが明らかにされている。この領域では、溶鋼内部から
ＣＯ気泡発生が活発に起こっており、ガス成分含有物質
を溶鋼に添加して、気・液反応界面積を拡大しても脱炭
反応の促進には効果が小さい。Generally, the decarburization reaction of molten steel under reduced pressure is roughly classified into the following three types. That is, [C] and oxygen (hereinafter referred to as [O] in the molten steel and refractory surface.
With the formation of CO bubbles. On the free surface of molten steel exposed to a reduced pressure atmosphere,
Reaction between [C] and [O]. Reaction between [C] and [O] occurring at the interface between the molten steel and argon bubbles blown into the molten steel. Classified as and. Among these reactions, the [C] concentration was 0.
It has been clarified that the reaction is dominant in the region of more than 020 mass%. In this region, CO bubbles are actively generated from inside the molten steel, and even if a gas component-containing substance is added to the molten steel to increase the gas-liquid reaction interface area, the effect of promoting the decarburization reaction is small.
【０００８】［Ｃ］濃度が０．０２０ｍａｓｓ％以下、
０．００５ｍａｓｓ％超の領域では、の反応の割合が
［Ｃ］濃度の低下とともに小さくなり、気・液反応界面
積を増大させ脱炭反応を促進させるため、ガス発生物質
を添加することは重要であるが、ガス発生物質添加によ
る脱炭反応促進効果は不十分である。[C] concentration is 0.020 mass% or less,
In the range of more than 0.005 mass%, the reaction rate of becomes small as the concentration of [C] decreases and increases the gas-liquid reaction interface area to accelerate the decarburization reaction, so it is important to add a gas generating substance. However, the effect of promoting the decarburization reaction by adding the gas generating substance is insufficient.
【０００９】一方、［Ｃ］濃度が０．００５ｍａｓｓ％
以下の領域では、脱炭反応は、の溶鋼自由表面及び
のアルゴン気泡と溶鋼との界面での反応が主体となる。
この領域では、気・液反応界面積を大きくすることが脱
炭反応の促進には特に重要である。On the other hand, the [C] concentration is 0.005 mass%
In the following region, the decarburization reaction mainly consists of the reaction at the free surface of the molten steel and at the interface between the argon bubbles and the molten steel.
In this region, increasing the gas-liquid reaction interface area is particularly important for promoting the decarburization reaction.
【００１０】脱炭促進のために溶鋼に添加すべきガス成
分含有物質は、溶鋼に接触したときすぐに分解し、ガス
を発生させ、かつ、炭素源を含有しないものが望まし
い。したがって、ガス成分を含有する物質として、Ｃａ
（ＯＨ）2 ，Ｍｇ（ＯＨ）2 ，Ｆｅ（ＯＨ）2 を用いる
こととする。さらに、これらの物質を単独で添加して
も、二種以上を混合してもよく脱炭促進効果は同等であ
る。The gas component-containing substance to be added to the molten steel for promoting decarburization is preferably one which decomposes immediately upon contact with the molten steel to generate a gas and does not contain a carbon source. Therefore, as a substance containing a gas component, Ca
(OH) 2 , Mg (OH) 2 , and Fe (OH) 2 are used. Furthermore, these substances may be added alone or in combination of two or more, and the decarburization promoting effect is the same.
【００１１】Ｃａ（ＯＨ）2 ，Ｍｇ（ＯＨ）2 ，Ｆｅ
（ＯＨ）2 を溶鋼に添加したときにはそれぞれ（ａ）
式，（ｂ）式、（ｃ）式に示す反応により、気泡が発生
する。Ca (OH) 2 , Mg (OH) 2 , Fe
When (OH) 2 is added to the molten steel, (a)
Bubbles are generated by the reactions shown in the equations, (b) and (c).
【００１２】 Ｃａ（ＯＨ）2 →ＣａＯ＋Ｈ2 Ｏ→ＣａＯ＋［Ｏ］＋Ｈ2 （ａ） Ｍｇ（ＯＨ）2 →ＭｇＯ＋Ｈ2 Ｏ→ＭｇＯ＋［Ｏ］＋Ｈ2 （ｂ） Ｆｅ（ＯＨ）2 →ＦｅＯ＋Ｈ2 Ｏ→ＦｅＯ＋［Ｏ］＋Ｈ2 （ｃ） １モルのＣａ（ＯＨ）2 ，Ｍｇ（ＯＨ）2 ，Ｆｅ（Ｏ
Ｈ）2 より１モルのＨ2ＯガスあるいはＨ2 ガスが発生
する。Ca (OH) 2 → CaO + H 2 O → CaO + [O] + H 2 (a) Mg (OH) 2 → MgO + H 2 O → MgO + [O] + H 2 (b) Fe (OH) 2 → FeO + H 2 O → FeO + [O] + H 2 (c) 1 mol of Ca (OH) 2 , Mg (OH) 2 , Fe (O
From H) 2 , 1 mol of H 2 O gas or H 2 gas is generated.
【００１３】Ｃａ（ＯＨ）2 ，Ｍｇ（ＯＨ）2 ，Ｆｅ
（ＯＨ）2 を溶鋼に添加し、脱炭を促進させるために
は、その添加速度が重要である。そこで、つぎにこれら
のガス成分含有固体物質の溶鋼への添加速度を溶鋼トン
当り毎分０．７５モル以上７．５モル以下に限定した理
由について述べる。Ca (OH) 2 , Mg (OH) 2 , Fe
In order to add (OH) 2 to molten steel and accelerate decarburization, its addition rate is important. Therefore, the reason why the addition rate of these gas component-containing solid substances to the molten steel is limited to 0.75 mol / min to 7.5 mol / min of molten steel will be described.
【００１４】前述したように、［Ｃ］濃度が０．００５
ｍａｓｓ％以下では、溶鋼内部から発生するＣＯガスの
量が少なくなり、真空槽内の自由表面がガスによって乱
される度合いが小さくなる。そのため気・液反応界面積
が小さくなり、溶鋼自由表面での脱炭速度が小さくな
る。そこで、溶鋼内部からのＣＯガス発生量の減少を上
記ガス成分含有固体物質を添加することによって補うこ
とにより脱炭を促進することができる。As described above, the [C] concentration is 0.005.
If it is less than mass%, the amount of CO gas generated from the inside of the molten steel becomes small, and the degree to which the free surface in the vacuum chamber is disturbed by the gas becomes small. Therefore, the gas-liquid reaction interface area becomes small, and the decarburization rate at the molten steel free surface becomes small. Therefore, decarburization can be promoted by supplementing the decrease in the amount of CO gas generated from inside the molten steel by adding the gas component-containing solid substance.
【００１５】通常の真空脱ガス設備では、［Ｃ］濃度が
０．００５ｍａｓｓ％のときには、（ｄ）式で表わされ
る脱炭速度の容量係数ｋcとしては、０．２（１／ｍｉ
ｎ）程度の値が得られている。In the usual vacuum degassing equipment, when the [C] concentration is 0.005 mass%, the capacity coefficient k c of the decarburization rate represented by the equation (d) is 0.2 (1 / mi).
Values around n) have been obtained.
【００１６】 −ｄ［ｍａｓｓ％Ｃ］／ｄｔ＝ｋc・［ｍａｓｓ％Ｃ］ （ｄ） ここで、［ｍａｓｓ％Ｃ］は、溶鋼中の炭素濃度（ｍｓ
ｓａ％）、ｔは時間、ｋcは脱炭反応の容量係数（１／
ｍｉｎ）をそれぞれ表わす。-D [mass% C] / dt = k c · [mass% C] (d) Here, [mass% C] is the carbon concentration (ms) in the molten steel.
sa%), t is time, and k c is the capacity coefficient of the decarburization reaction (1 /
min) respectively.
【００１７】［Ｃ］濃度が０．００５ｍａｓｓ％のとき
ｋcが０．２（１／ｍｉｎ）であるとき、ＣＯガス発生
量はおよそ溶鋼１トン当り毎分０．７５モルである。
［Ｃ］濃度が０．００５ｍａｓｓ％以下では、［Ｃ］濃
度の低下とともにｋcが小さくなり、溶鋼内部から発生
するＣＯガスの量が少なくなる。（ａ）式〜（ｃ）式に
示すように、上記ガス成分含有固体物質１モルを溶鋼に
添加したとき、１モルのガスが発生するから、溶鋼１ト
ン当りに毎分０．７５モルのガスを発生させるために
は、溶鋼１トン当り０．７５モルの上記固体物質を添加
すればよい。そうすることによって、［Ｃ］濃度が０．
００５ｍａｓｓ％以下の領域でも、［Ｃ］濃度が０．０
０５ｍａｓｓ％のときに溶鋼内部から発生するＣＯガス
と同等の流量のガスを溶鋼内部から発生させることがで
きる。When the [C] concentration is 0.005 mass% and k c is 0.2 (1 / min), the amount of CO gas generated is about 0.75 mol / min / ton of molten steel.
When the [C] concentration is 0.005 mass% or less, k c becomes small as the [C] concentration decreases, and the amount of CO gas generated from the inside of the molten steel becomes small. As shown in equations (a) to (c), when 1 mol of the gas component-containing solid substance is added to the molten steel, 1 mol of gas is generated. In order to generate gas, 0.75 mol of the above solid substance may be added per ton of molten steel. By doing so, the [C] concentration becomes 0.
Even in the range of 005 mass% or less, the [C] concentration is 0.0
A gas having the same flow rate as the CO gas generated from the inside of the molten steel when the content is 05 mass% can be generated from the inside of the molten steel.
【００１８】図１に、脱炭促進効果に及ぼすＭｇ（Ｏ
Ｈ）2 の溶鋼への添加速度の影響を示す。ここでは、脱
炭促進効果は、Ｍｇ（ＯＨ）2 を溶鋼１トン当り毎分
０．７５モルの添加速度で添加したときの脱炭促進量を
基準として相対評価した。なお、図１の添加速度と脱炭
促進効果との関係はＣａ（ＯＨ）2 ，Ｆｅ（ＯＨ）2 の
場合も同様であった Ｍｇ（ＯＨ）2 の溶鋼への添加速度が大きいほど、脱炭
促進効果は大きくなるが、溶鋼１トン当りに毎分７．５
モル超の添加速度で添加すると、生成されるＭｇＯが溶
鋼表面を被覆し、脱炭速度がかえって小さくなること
が、実験により確かめられた。よって、添加速度の上限
は溶鋼１トン当り毎分７．５モルとする。FIG. 1 shows the effect of Mg (O) on the decarburization promoting effect.
The effect of the addition rate of H) 2 to molten steel is shown. Here, the decarburization accelerating effect was relatively evaluated based on the decarburization accelerating amount when Mg (OH) 2 was added at an addition rate of 0.75 mol / min of molten steel. Note that the relationship between the addition rate and the decarburization promoting effect in FIG. 1 was the same in the case of Ca (OH) 2 and Fe (OH) 2 as the addition rate of Mg (OH) 2 to the molten steel increased. The charcoal promotion effect is large, but 7.5 per minute per ton of molten steel
It was confirmed by experiments that when added at an addition rate exceeding the mole, the produced MgO coats the molten steel surface and the decarburization rate is rather reduced. Therefore, the upper limit of the addition rate is 7.5 mol / min of molten steel.
【００１９】以上より、Ｃａ（ＯＨ）2 ，Ｍｇ（ＯＨ）
2 ，Ｆｅ（ＯＨ）2 の一種もしくは二種以上の混合物の
溶鋼への添加速度は溶鋼１トンあたりに毎分０．７５モ
ル以上、７．５モル以下の範囲とする。From the above, Ca (OH) 2 , Mg (OH)
2, Fe (OH) 2 in one or the rate of addition of the molten steel of two or more of the mixture of molten steel 1 per tonne per minute 0.75 mol or more, in the range of 7.5 mol or less.
【００２０】Ｃａ（ＯＨ）2 ，Ｍｇ（ＯＨ）2 ，Ｆｅ
（ＯＨ）2 の溶鋼への添加は連続的であっても、断続的
であってもよく脱炭促進効果はいずれも同等である。Ca (OH) 2 , Mg (OH) 2 , Fe
The addition of (OH) 2 to the molten steel may be continuous or intermittent, and the effects of promoting decarburization are the same.
【００２１】Ｃａ（ＯＨ）2 ，Ｍｇ（ＯＨ）2 ，Ｆｅ
（ＯＨ）2 の溶鋼への添加方法は、溶鋼の上方から添加
する方法、溶鋼中にランスを浸漬させて、不活性ガスを
搬送ガスとして溶鋼中に吹込む方法のいずれでもよい。Ca (OH) 2 , Mg (OH) 2 , Fe
The method of adding (OH) 2 to the molten steel may be either a method of adding from above the molten steel or a method of immersing a lance in the molten steel and blowing an inert gas into the molten steel as a carrier gas.
【００２２】水素含有ガスを溶鋼中に吹込む際、ガスを
吹込むためのポーランスレンガや浸漬ランスの異常溶損
のため安定して溶鋼にガスを吹込むことは困難である。
さらに、水素を一旦溶鋼中に溶解させるため、脱炭処理
の後に水素を除去する工程が必要である。このことは、
処理時間の延長をもたらし、経済的には不利である。When the hydrogen-containing gas is blown into the molten steel, it is difficult to stably blow the gas into the molten steel due to abnormal melting damage of the porance brick and the immersion lance for blowing the gas.
Furthermore, since hydrogen is once dissolved in molten steel, a step of removing hydrogen after the decarburization treatment is necessary. This is
This results in extension of processing time and is economically disadvantageous.
【００２３】本発明の方法のように固形物質を溶鋼に添
加する場合には、ポーラスレンガやランスの異常溶損は
なく、溶鋼中に溶解する水素の量も少ないため、脱水素
工程も不要である。When a solid substance is added to molten steel as in the method of the present invention, there is no abnormal erosion loss of porous bricks or lances, and the amount of hydrogen dissolved in the molten steel is small, so a dehydrogenation step is not necessary. is there.
【００２４】さらに、溶鋼に添加するガス成分含有物質
の粒径も重要である。すなわち、粒径が小さすぎると、
真空排気のためのガスの流れにより系外に運ばれ溶鋼へ
の添加歩留りが小さくなるため不利である。また、粒径
が大きすぎると、溶鋼に添加したときに発生する気泡が
大きくなり、単位添加量当りの気・液反応界面積増大効
果が小さい。粒径について、詳細に調査した結果、０．
２ｍｍ以上１０ｍｍ以下であれば、添加歩留りが大き
く、気・液反応面積増大効果も大きく、脱炭促進には効
果的であることが明らかとなった。したがって、ガス成
分含有物質の粒径は０．２ｍｍ以上１０ｍｍ以下が望ま
しい。Further, the particle size of the gas component-containing substance added to the molten steel is also important. That is, if the particle size is too small,
This is disadvantageous because it is carried out of the system by the flow of gas for evacuation and the yield of addition to molten steel is reduced. On the other hand, if the particle size is too large, bubbles generated when added to molten steel become large, and the effect of increasing the gas-liquid reaction interface area per unit addition amount is small. As a result of detailed investigation of the particle size, 0.
It was clarified that if it is 2 mm or more and 10 mm or less, the yield of addition is large, the effect of increasing the gas / liquid reaction area is large, and it is effective in promoting decarburization. Therefore, the particle size of the gas component-containing substance is preferably 0.2 mm or more and 10 mm or less.
【００２５】本発明の方法は、種々の真空脱ガス装置、
例えば、ＲＨ，ＤＨ，ＶＯＤに適用することができる。The method of the present invention comprises various vacuum degassing devices,
For example, it can be applied to RH, DH, and VOD.
【００２６】さらに、本発明の方法は、脱炭反応と同様
に気・液界面で起こる脱窒反応の促進にも有効である。Furthermore, the method of the present invention is also effective in promoting the denitrification reaction that occurs at the gas-liquid interface as in the decarburization reaction.
【００２７】[0027]
実施例−１ 初期成分が［Ｃ］；０．０２ｍａｓｓ％，［Ｓｉ］；
０．１ｍａｓｓ％以下、［Ｍｎ］；０．０１〜０．５ｍ
ａｓｓ％，［Ｐ］；０．００５〜０．０２ｍａｓｓ％、
［Ｓ］；０．００３〜０．１５ｍａｓｓ％，［Ａｌ］；
０．００２ｍａｓｓ％以下で重量が３００トン溶鋼をＲ
Ｈ真空脱ガス装置を用いて脱炭処理を実施した。真空槽
内の溶鋼に上方から粒径１〜２ｍｍのＭｇ（ＯＨ）2 を
毎分１３．０５ｋｇ（溶鋼１トン当り毎分０．７５モ
ル）の添加速度で連続的に添加した。このときの［Ｃ］
濃度の経時変化を図２に示す。比較例１は、真空槽内の
溶鋼に上方から粒径１〜２ｍｍのＭｇ（ＯＨ）2 を毎分
８．７ｋｇ（溶鋼１トン当り毎分０．５モル）の添加速
度で連続的に添加した場合の［Ｃ］濃度の経時変化であ
る。Ｍｇ（ＯＨ）2 の添加速度が溶鋼１トン当り毎分
０．５モルの場合は脱炭促進効果が小さいのに対して、
添加速度が溶鋼１トン当り毎分０．７５モルで添加した
場合には、０．００１ｍａｓｓ％以下まで［Ｃ］濃度を
低減することができた。Example-1 Initial component is [C]; 0.02 mass%, [Si];
0.1 mass% or less, [Mn]; 0.01 to 0.5 m
%, [P]; 0.005-0.02 mass%,
[S]; 0.003-0.15 mass%, [Al];
R is less than 0.002 mass% and weight is 300 tons
Decarburization treatment was performed using an H 2 vacuum degasser. Mg (OH) 2 having a particle size of 1 to 2 mm was continuously added to the molten steel in the vacuum chamber from the top at an addition rate of 13.05 kg / min (0.75 mol / min / ton of molten steel). [C] at this time
The time-dependent change in concentration is shown in FIG. In Comparative Example 1, Mg (OH) 2 having a particle size of 1 to 2 mm was continuously added to the molten steel in the vacuum chamber from above at an addition rate of 8.7 kg / min (0.5 mol / min / ton of molten steel). It is a change with time of the [C] concentration in the case of performing. When the addition rate of Mg (OH) 2 is 0.5 mol per ton of molten steel, the decarburization promoting effect is small, whereas
When the addition rate was 0.75 mol per minute per ton of molten steel, the [C] concentration could be reduced to 0.001 mass% or less.
【００２８】実施例−２ 初期成分が［Ｃ］；０．０２ｍａｓｓ％，［Ｓｉ］；
０．１ｍａｓｓ％以下、［Ｍｎ］；０．０１〜０．５ｍ
ａｓｓ％，［Ｐ］；０．００５〜０．０２ｍａｓｓ％，
［Ｓ］；０．００３〜０．０１５ｍａｓｓ％，［Ａ
ｌ］；０．００２ｍａｓｓ％以下で重量が３００トンの
溶鋼をＲＨ真空脱ガス装置を用いて脱炭処理を実施し
た。真空槽内の溶鋼に上方から粒径１〜２ｍｍのＭｇ
（ＯＨ）2 を毎分１３０．５ｋｇ（溶鋼１トン当り毎分
７．５モル）の添加速度で連続的に添加した。このとき
の［Ｃ］濃度の経時変化を図３に示す。比較例２は、真
空槽内の溶鋼に上方から粒径１〜２ｍｍＭｇ（ＯＨ）2
を毎分１７４ｋｇ（溶鋼１トン当り毎分１０モル）の添
加速度で連続的に添加した場合の［Ｃ］濃度の経時変化
である。Ｍｇ（ＯＨ）2 の添加速度が溶鋼１トン当り毎
分１０モルの場合は脱炭促進効果が小さいのに対して、
添加速度が溶鋼１トン当り毎分７．５モルで添加した場
合には、［Ｃ］濃度を０．００１ｍａｓｓ％以下まで低
減することができた。Example-2 Initial component is [C]; 0.02 mass%, [Si];
0.1 mass% or less, [Mn]; 0.01 to 0.5 m
%, [P]; 0.005-0.02 mass%,
[S]; 0.003 to 0.015 mass%, [A
l]; 0.002 mass% or less and a weight of 300 tons of molten steel were decarburized using an RH vacuum degassing apparatus. Mg from the top of the molten steel in the vacuum chamber with a particle size of 1-2 mm
(OH) 2 was continuously added at an addition rate of 130.5 kg / min (7.5 mol / ton of molten steel / min). FIG. 3 shows changes with time of the [C] concentration at this time. In Comparative Example 2, the molten steel in the vacuum chamber was added with a particle size of 1 to 2 mm Mg (OH) 2 from above.
Is a change with time of the [C] concentration when is continuously added at an addition rate of 174 kg / min (10 mol / ton of molten steel). When the addition rate of Mg (OH) 2 is 10 mol / min of molten steel, the decarburization promoting effect is small, whereas
When the addition rate was 7.5 mol / min of molten steel, the [C] concentration could be reduced to 0.001 mass% or less.
【００２９】実施例−３ 初期成分が［Ｃ］；０．０２ｍａｓｓ％，［Ｓｉ］；
０．１ｍａｓｓ％以下、［Ｍｎ］；０．０１〜０．５ｍ
ａｓｓ％，［Ｐ］；０．００５〜０．０２ｍａｓｓ％，
［Ｓ］；０．００３〜０．０１５ｍａｓｓ％，［Ａ
ｌ］；０．００２ｍａｓｓ％以下で重量が３００トンの
溶鋼をＲＨ真空脱ガス装置を用いて脱炭処理を実施し
た。真空槽内の溶鋼に上方から粒径１〜２ｍｍの表１に
示すガス成分含有固体物質を溶鋼１トン当り毎分０．７
５モルの添加速度で連続的に添加した。このときの脱炭
処理開始から２０分後の［Ｃ］濃度を表１に併示した。
Ｃａ（ＯＨ）2 ，Ｍｇ（ＯＨ）2 ，Ｆｅ（ＯＨ）2 及び
Ｍｇ（ＯＨ）2 とＦｅ（ＯＨ）2 の混合物を添加した場
合にはいずれも［Ｃ］濃度が０．００１ｍａｓｓ％以下
にすることができたのに対して、炭素源を含有するＣａ
ＣＯ3 を添加した場合には［Ｃ］濃度を０．００１ｍａ
ｓｓ％以下に低減することができなかった。Example 3 Initial component is [C]; 0.02 mass%, [Si];
0.1 mass% or less, [Mn]; 0.01 to 0.5 m
%, [P]; 0.005-0.02 mass%,
[S]; 0.003 to 0.015 mass%, [A
l]; 0.002 mass% or less and a weight of 300 tons of molten steel were decarburized using an RH vacuum degassing apparatus. A gas component-containing solid substance having a particle size of 1 to 2 mm shown in Table 1 was added to the molten steel in the vacuum tank from the top at 0.7 per minute per ton of molten steel.
It was added continuously at an addition rate of 5 mol. The [C] concentration 20 minutes after the start of the decarburization treatment is also shown in Table 1.
When Ca (OH) 2 , Mg (OH) 2 , Fe (OH) 2 and a mixture of Mg (OH) 2 and Fe (OH) 2 were added, the [C] concentration became 0.001 mass% or less. Whereas it could be, Ca containing a carbon source
When CO 3 is added, the [C] concentration is 0.001 ma.
It could not be reduced to ss% or less.
【００３０】[0030]
【表１】 [Table 1]
【００３１】[0031]
【発明の効果】本発明により、従来の水素を一担溶鋼中
に溶解させる、あるいは、Ｃ含有のガス成分含有固体物
を添加する事なしに、溶鋼の脱炭反応を促進することが
でき、後工程での脱水素処理、あるいは脱炭処理の延長
なしに、［Ｃ］濃度が０．００１ｍａｓｓ％以下の極低
炭素鋼を経済的に、且つ、効率的に、溶製できるように
なった。According to the present invention, it is possible to accelerate the decarburization reaction of molten steel without dissolving hydrogen in the conventional molten steel or adding a solid substance containing a gas component containing C, It has become possible to economically and efficiently produce an extremely low carbon steel having a [C] concentration of 0.001 mass% or less without extending the dehydrogenation treatment or the decarburization treatment in the subsequent process. ..
【図１】脱炭促進効果に及ぼすＭｇ（ＯＨ）2 添加速度
の影響を示す図。FIG. 1 is a diagram showing the effect of a Mg (OH) 2 addition rate on a decarburization promoting effect.
【図２】［Ｃ］濃度の経時変化を示す図。FIG. 2 is a view showing a change with time of [C] concentration.
【図３】［Ｃ］濃度の経時変化を示す図。FIG. 3 is a view showing a change with time of [C] concentration.
Claims (1)
するにあたり、溶鋼中の炭素濃度が０．０２０ｍａｓｓ
％以下の領域で、真空槽内の溶鋼に、Ｃａ（ＯＨ）2 ，
Ｍｇ（ＯＨ）2 ，Ｆｅ（ＯＨ）2 の一種もしくは二種以
上の混合物を溶鋼１トンあたりに毎分０．７５モル以
上，７．５モル以下の添加速度で添加することを特徴と
する極低炭素鋼の溶製方法。1. When performing decarburization treatment of molten steel under reduced pressure, the carbon concentration in the molten steel is 0.020 mass.
% Or less, in the molten steel in the vacuum chamber, Ca (OH) 2 ,
A pole characterized by adding one or a mixture of two or more of Mg (OH) 2 and Fe (OH) 2 at an addition rate of 0.75 mol or more and 7.5 mol or less per ton of molten steel per minute. Method for melting low carbon steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8375892A JPH05287360A (en) | 1992-04-06 | 1992-04-06 | Method for melting extremely low carbon steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8375892A JPH05287360A (en) | 1992-04-06 | 1992-04-06 | Method for melting extremely low carbon steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05287360A true JPH05287360A (en) | 1993-11-02 |
Family
ID=13811467
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8375892A Withdrawn JPH05287360A (en) | 1992-04-06 | 1992-04-06 | Method for melting extremely low carbon steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05287360A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108220532A (en) * | 2016-12-13 | 2018-06-29 | 鞍钢股份有限公司 | Secondary refining method for improving cleanliness of molten steel |
| CN108611465A (en) * | 2016-12-13 | 2018-10-02 | 鞍钢股份有限公司 | Molten steel refining method for improving RH decarburization rate |
-
1992
- 1992-04-06 JP JP8375892A patent/JPH05287360A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108220532A (en) * | 2016-12-13 | 2018-06-29 | 鞍钢股份有限公司 | Secondary refining method for improving cleanliness of molten steel |
| CN108611465A (en) * | 2016-12-13 | 2018-10-02 | 鞍钢股份有限公司 | Molten steel refining method for improving RH decarburization rate |
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