JP4882249B2 - Manufacturing method of high clean steel - Google Patents
Manufacturing method of high clean steel Download PDFInfo
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- JP4882249B2 JP4882249B2 JP2005070717A JP2005070717A JP4882249B2 JP 4882249 B2 JP4882249 B2 JP 4882249B2 JP 2005070717 A JP2005070717 A JP 2005070717A JP 2005070717 A JP2005070717 A JP 2005070717A JP 4882249 B2 JP4882249 B2 JP 4882249B2
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- 229910000831 Steel Inorganic materials 0.000 title claims description 95
- 239000010959 steel Substances 0.000 title claims description 95
- 238000004519 manufacturing process Methods 0.000 title claims description 10
- 239000007789 gas Substances 0.000 claims description 68
- 238000000034 method Methods 0.000 claims description 43
- 239000002893 slag Substances 0.000 claims description 29
- 238000009849 vacuum degassing Methods 0.000 claims description 28
- 238000007664 blowing Methods 0.000 claims description 27
- 238000011282 treatment Methods 0.000 claims description 21
- 238000007670 refining Methods 0.000 claims description 20
- 239000003607 modifier Substances 0.000 claims description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 6
- 238000012545 processing Methods 0.000 claims description 4
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- 238000007667 floating Methods 0.000 claims description 3
- 229930195733 hydrocarbon Natural products 0.000 claims description 3
- 150000002430 hydrocarbons Chemical class 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 2
- 239000000203 mixture Substances 0.000 description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- 229910052760 oxygen Inorganic materials 0.000 description 8
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000010405 reoxidation reaction Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 238000009749 continuous casting Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 3
- 230000003749 cleanliness Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 230000001737 promoting effect Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 230000005587 bubbling Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000011086 high cleaning Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- RRZKHZBOZDIQJG-UHFFFAOYSA-N azane;manganese Chemical compound N.[Mn] RRZKHZBOZDIQJG-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
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Description
本発明は、高清浄鋼の製造方法に関し、とくに、真空脱ガス装置において、溶鋼中の介在物を効果的に除去することにより、高清浄鋼を確実に製造するための方法を提案する。 The present invention relates to a method for producing highly clean steel, and in particular, proposes a method for reliably producing highly clean steel by effectively removing inclusions in molten steel in a vacuum degassing apparatus.
近年、鉄鋼材料の多くは、高機能化および高品質化に向っており、鋼中の不純物元素を極限まで低減する努力が払われている。ところで、鋼中の不純物元素の１つである酸素は、鋼中に介在物（酸化物）として存在しており、これが鋼材における各種欠陥の原因となることが知られている。そのために、介在物のない高清浄鋼の製造技術が検討されている。そうした高清浄鋼を得るには、介在物原因である酸化物の生成そのものを抑制するか、生成した酸化物を確実に分離除去することが必要になる。
こうした酸化物系介在物生成の要因として、溶鋼上にあるスラグからの再酸化がある。そうした再酸化を抑制する方法の１つとして、スラグを低酸化度のものに改質する方法がある。この方法は、転炉から溶鋼とともに取鍋へ流出した酸化度の高いスラグの全部あるいは一部を除去し、新たに造滓剤を添加して、アーク加熱を行いながら長時間攪拌する方法（ＬＦ法）として知られている。
In recent years, many of steel materials are suitable for high functionality and high quality, and efforts have been made to reduce impurity elements in steel to the limit. Incidentally, oxygen, which is one of the impurity elements in steel, is present as inclusions (oxides) in steel, and it is known that this causes various defects in steel materials. For this reason, a technique for producing highly clean steel without inclusions has been studied. In order to obtain such a highly clean steel, it is necessary to suppress the oxide itself that is the cause of inclusions, or to reliably separate and remove the generated oxide.
As a factor of the generation of such oxide inclusions, there is reoxidation from slag on molten steel. One method for suppressing such reoxidation is to modify slag to a low oxidation degree. This method removes all or part of the highly oxidized slag that has flowed from the converter to the ladle along with the molten steel, newly added a slagging agent, and stirred for a long time while performing arc heating (LF) Act).
また、前記介在物分離除去の他の方法としては、真空脱ガス処理を長時間行う方法がある。その他、二次精錬容器内の溶鋼中に可溶性ガスを溶解させ、その後、容器内を急速に減圧して該溶鋼中に微細なガス気泡を発生させることにより、溶鋼中に浮遊している介在物をこの気泡に捕捉させ、帯同させた状態で浮上させて分離する方法がある。（例えば、特許文献１参照。）
しかしながら、上記ＬＦ法は、スラグ除去の処理が必要で、弱い攪拌処理を長時間を行う必要があるためにアーク加熱が不可欠となり、コストがかかるという問題がある。しかも、長時間の処理になるため、後工程である真空脱ガス処理工程や連続鋳造工程との連繋が悪くなるという問題もあった。さらには、真空脱ガス処理を長時間行うため、溶鋼の温度低下が大きく、転炉での出鋼温度を高くするか、ＬＦ処理時に加熱を行わなければならないという問題もあった。 However, the LF method requires a slag removal process, and it is necessary to perform a weak stirring process for a long time. Therefore, there is a problem that arc heating is indispensable and cost is high. Moreover, since it takes a long time, there is a problem in that the connection with the vacuum degassing process and the continuous casting process, which are subsequent processes, becomes worse. Furthermore, since the vacuum degassing process is performed for a long time, the temperature drop of the molten steel is large, and there has been a problem that the steel output temperature in the converter must be increased or heating must be performed during the LF process.
また、真空脱ガス法の長時間処理や上記特許文献１に記載の方法では、介在物の分離除去を促進しても、溶鋼上のスラグが転炉から流出したままの状態であることから酸化度が高いため、再酸化によって新たな介在物の生成を招きやすく、分離除去効果が減殺されるという問題を抱えていた。
Further, in the long-time treatment of the vacuum degassing method and the method described in
本発明の目的は、従来技術が抱えている上述した問題に鑑み、鋼中の非金属介在物の生成を抑制する一方で、分離除去を促進することで、介在物の極めて少ない高清浄鋼を安定して製造する方法を提供することにある。 The object of the present invention is to solve the above-mentioned problems of the prior art, while suppressing the formation of non-metallic inclusions in the steel, while promoting the separation and removal, thereby making it possible to obtain a highly clean steel with very few inclusions. The object is to provide a method for stable production.
上記目的を実現するために、発明者らは鋭意検討を行った。その検討の過程で発明者らは、まず、低酸化度のスラグを得るためには、転炉から流出したスラグの組成を変える（改質する）必要がある。しかし、単に、改質剤をスラグ上に添加するだけでは、スラグと改質剤の混合、溶融が十分に行われないため、改質が不充分になるということがわかった。そこで、発明者らは、転炉出鋼流の落下エネルギーを利用して、前記改質剤を出鋼流中に添加することとした。しかし、この方法では、熱不足のためにスラグ組成や溶融状態にばらつきを生じることがわかった。そして、その解決のためには、溶鋼からスラグへの熱供給を図りつつ、攪拌することが有効であることを突き止めた。即ち、少なくとも、真空脱ガス処理前の取鍋中に、溶鋼の攪拌に寄与するガス、例えば、溶鋼に可溶性のガスを吹き込むことで、このときに起こるガスバブリング作用によって、スラグの組成、溶融状態の均質化を促すことにした。 In order to achieve the above object, the inventors have conducted intensive studies. In the course of the study, the inventors first need to change (reform) the composition of the slag flowing out of the converter in order to obtain a slag having a low oxidation degree. However, it has been found that simply adding a modifier on the slag does not sufficiently mix and melt the slag and the modifier, resulting in insufficient modification. Therefore, the inventors decided to add the modifier to the outgoing steel flow using the falling energy of the outgoing steel flow from the converter. However, this method has been found to cause variations in slag composition and molten state due to lack of heat. In order to solve this problem, the inventors have found that it is effective to stir while supplying heat from the molten steel to the slag. That is, at least the gas that contributes to the stirring of the molten steel, for example, a gas soluble in the molten steel, is blown into the ladle before the vacuum degassing treatment. It was decided to promote homogenization.
ただし、上述したように、出鋼流への造滓剤の添加や取鍋内への可溶性ガスの吹き込みは、却って溶鋼中へのスラグの巻き込みを促進し、その一部が介在物としてそのまま溶鋼中へ残留しやすくすることも考えられるので、この場合、介在物の除去処理を促進する手段の採用が必要である。
そこで、本発明では、真空脱ガス装置での介在物の除去を促進する方法として、溶鋼中への可溶性ガスの溶解後、雰囲気を減圧することで該溶鋼中に微細な気泡を発生させ、その気泡に微細な介在物を捕捉させるという方法で、介在物の分離浮上を促進させるようにした。
ただし、可溶性ガスを真空脱ガス処理の過程で添加すると、処理時間が延びてしまうため好ましくない。そこで、転炉および取鍋への可溶性ガスの供給について検討した。その検討結果によると、転炉精錬中もしくは精錬の完了後にのみ、可溶性ガス、あるいは窒素を発生する合金の添加を行ったところ、添加の歩留が安定せず、真空脱ガス処理前の可溶性ガス成分濃度にばらつきが生じ、真空脱ガス処理過程でのバブリングガス発生にばらつきが生じた。一方で、取鍋のみへの可溶性ガスの吹き込みでは、温度低下の懸念があることから長時間の処理ができないため、可溶性ガスの溶解量が少なく、添加効果が不十分になるという結果となった。
However, as described above, the addition of a slagging agent to the steel flow and the blowing of soluble gas into the ladle promotes the slag to be entrained in the molten steel, and part of the molten steel is left as an inclusion. In this case, it is necessary to employ a means for promoting the inclusion removal process.
Therefore, in the present invention, as a method of promoting the removal of inclusions in the vacuum degassing apparatus, after dissolving the soluble gas in the molten steel, the atmosphere is decompressed to generate fine bubbles in the molten steel. The method of trapping fine inclusions in the bubbles promotes the separation and floating of the inclusions.
However, it is not preferable to add a soluble gas during the vacuum degassing process because the processing time is extended. Therefore, the supply of soluble gas to the converter and ladle was examined. According to the results of the study, when a soluble gas or an alloy generating nitrogen was added only during converter refining or after completion of refining, the yield of the addition was not stable, and the soluble gas before vacuum degassing was processed. The component concentration varied, and the bubbling gas generation during the vacuum degassing process varied. On the other hand, blowing soluble gas only into the ladle, because there is a concern about the temperature drop, it can not be treated for a long time, so the amount of soluble gas dissolved is small and the effect of addition becomes insufficient .
さらに、発明者らは、１次的に可溶性ガスを転炉の精錬中もしくは精錬完了後の出鋼前に添加すると共に、さらに、２次的に真空脱ガス処理の前にも取鍋に可溶性ガスの吹き込みを行うという２段階のガス吹き込みについて実験した。その結果、確かに出鍋直後の可溶性ガスの成分濃度にばらつきはあったが、取鍋でのガス吹き込み処理後は、可溶性ガス成分濃度はほぼ同程度となり、真空脱ガス装置でのガスバブリングの効果にばらつきを生じさせことなく、均質化することができ、介在物の除去に効果が見られた。 In addition, the inventors added primary soluble gas during the refining of the converter or before the steel output after completion of the refining, and further, the secondary soluble in the ladle before the vacuum degassing treatment. An experiment was conducted on two-stage gas injection, that is, gas injection. As a result, the concentration of soluble gas components immediately after the ladle varied, but after the gas blowing treatment in the ladle, the concentration of soluble gas components was almost the same, and gas bubbling in the vacuum degassing device was almost the same. It was possible to homogenize without causing variations in the effect, and an effect was seen in the removal of inclusions.
本発明は、上述した知見に基づいて開発されたものであって、溶鋼の真空脱ガス処理に際し、被処理溶鋼中に予め可溶性ガスを溶解せしめ、次いで、その溶鋼を減圧処理することにより、このとき発生するガス気泡に該溶鋼中の介在物を捕捉させて浮上除去する高清浄鋼の製造方法において、
第１段階の処理として、前記可溶性ガスもしくは可溶性ガス発生物質を、転炉精錬中もしくは精錬完了後の段階で吹き込みまたは添加して溶解させ、
第２段階の処理として、転炉からの出鋼時には出鋼流に対してスラグ改質剤を添加し、
第３段階の処理として、真空脱ガス処理に先立つ取鍋内溶鋼中に可溶性ガスを再び単独または不活性ガスとともに吹き込み、
そして、前記可溶性ガスの吹き込みに当たっては、前記転炉精錬中もしくは精錬完了後の段階における１次吹込みと、前記真空脱ガス処理に先立つ取鍋内溶鋼中における段階における２次吹込みとの比率を、１〜１０：１とすることを特徴とする高清浄鋼の製造方法である。
The present invention has been developed on the basis of the above-described knowledge. In the vacuum degassing treatment of molten steel, the soluble gas is dissolved in advance in the molten steel to be treated, and then the molten steel is subjected to reduced pressure treatment. In the manufacturing method of the high clean steel that captures inclusions in the molten steel by the gas bubbles generated when it floats and removes,
As the first stage treatment, the soluble gas or the soluble gas generating substance is blown or added in the stage during or after converter refining or after completion of refining, and dissolved .
As a second stage treatment , a slag modifier is added to the outgoing steel flow at the time of steel output from the converter,
As the processing of the third stage, viewed write blown with again either alone or in inert gas soluble gas into the ladle in the molten steel prior to the vacuum degassing treatment,
And in blowing the soluble gas, the ratio of the primary blowing in the stage during the converter refining or after completion of the refining and the secondary blowing in the stage in the molten steel in the ladle prior to the vacuum degassing treatment Is a manufacturing method of high clean steel characterized by being 1 to 10: 1 .
本発明において、前記可溶性ガスは、鋼成分に応じ、窒素ガス、水素ガスまたは炭化水素系ガスのいずれか１種以上を用いることが有効である。 In the present invention, the soluble gas, depending on the steel composition, the nitrogen gas, and the Mochiiruko any one or more of hydrogen gas or a hydrocarbon gas is effective.
以上説明したように、本発明によれば、転炉精錬中あるいは精錬完了後と、真空脱ガス処理前との２段階に分けた可溶性ガスの添加と、転炉から取鍋への溶鋼出鋼時に出鋼流に対し、スラグ改質剤を添加するという方法を採用した結果、スラグ組成を低酸素化できると同時に、真空脱ガス処理前の溶鋼中可溶性ガス成分濃度のばらつきをなくすことができ、その結果、溶鋼のスラグによる再酸化が抑制される一方で、真空脱ガス処理段階では微細なガス発生による微細な介在物までも確実に除去することができ、ひいては介在物の極めて少ない高清浄鋼を安定して製造することができるようになった。 As described above, according to the present invention, the addition of soluble gas divided into two stages, during or after the refining of the converter, and before the vacuum degassing process, and the molten steel from the converter to the ladle As a result of adopting a method of adding a slag modifier to the outgoing steel flow sometimes, the slag composition can be reduced in oxygen and at the same time, the dispersion of soluble gas component concentration in the molten steel before vacuum degassing treatment can be eliminated. As a result, while reoxidation of molten steel by slag is suppressed, fine inclusions due to fine gas generation can be surely removed in the vacuum degassing treatment stage, and consequently, extremely clean with very little inclusions. Steel can be manufactured stably.
以下、本発明を実施する方法の概略を示す図に基づき、本発明方法の詳細を説明する。
本発明方法の第１の手段は、転炉２の脱炭精錬中あるいは脱炭精錬の完了後に、以下の操作のうちの１つ以上の方法を実施する。
１）上吹きランス３から可溶性ガスを溶鋼１浴面へ吹き付ける
２）底吹き羽口４から可溶性ガスを溶鋼１中へ吹き込む
３）可溶性ガス発生物質５を添加装置（図示せず）にて上方から溶鋼１中へ添加する
なお、可溶性ガスとしては、特に限定されないが、望ましく鋼の成分組成に応じて、窒素、水素、プロパン等の炭化水素系ガスのいずれかを用いる。その他、可溶性ガス発生物質５としても、鋼の成分組成に応じて、例えば、窒化マンガンや窒化アルミニウム等の固体を用いてもよい。
Hereinafter, the method of the present invention will be described in detail with reference to the drawings showing the outline of the method for carrying out the present invention.
The first means of the method of the present invention implements one or more of the following operations during or after the decarburization / refining of the
1) A soluble gas is blown from the top blowing lance 3 onto the
本発明の第２の手段は、上記の処理を終えた溶鋼１を取鍋７に出鋼するときに流出した転炉精錬スラグ６の組成を改質することである。そのため本発明では、出鋼流に対し、スラグ改質剤８を添加する。このスラグ改質剤８の組成、添加量は要求される溶鋼の清浄度によって最適化しておくことが好ましい。例えば、取鍋スラグを低融点化してＡｌ2Ｏ3介在物吸収能の高い組成にするため、溶鋼脱酸によるＡｌ2Ｏ3発生量を考慮して、ＣａＯ分を添加する方法、あるいはスラグ中ＳｉＯ2の低減を目的として一定のスラグ量を確保すると共に低融点化を確保するため、ＣａＯ−Ａｌ2Ｏ3混合フラックスを添加する方法などである。
The second means of the present invention is to modify the composition of the converter refining slag 6 that has flowed out when the
本発明の第３の手段は、出鋼終了後、取鍋７をガスインジェクション設備に移し、ここで取鍋内溶鋼中に可溶性ガスの２次吹き込みを行うことである。ガス吹き込み方法としては、浸漬ランス９からの上吹きか、底吹きが可能な取鍋であれば、底吹き羽口１０からの底吹きを行うか、あるいは上吹きを同時に行ってもよい。また、吹き込む可溶性ガスの量、吹込み時間等は、事前に可溶性ガスの溶解速度を実測しておき、その実測値に基づき処理後の可溶性ガス成分濃度が同等になるように調整する。このとき、処理前の可溶性ガス成分濃度を分析しておくことが好ましい。例えば、真空脱ガス装置での可溶性ガスの脱ガス速度と処理時間と可溶性ガス成分の最終目標値により、真空脱ガス処理前の可溶性ガス成分濃度が決まるので、その濃度に応じてガス吹込み条件を変更すればよい。なお、ある一定以上可溶性ガスを吹き込んでも、それ以上可溶性ガス成分濃度が上昇しない見かけの平衡濃度が最大値となるその濃度を狙う場合は、可溶性ガス吹き込み量、時間が多少多くなっても構わない。
上記可溶性ガスの２次吹き込み時に、攪拌が弱く、スラグの混合、溶融が不十分となる場合は、該可溶性ガスにアルゴンガス等の不活性ガスを所要量混合した混合ガスを用いることもよい。
なお、可溶性ガスの１次、２次吹込みに当っては、好ましくは１次吹込み量を多く配合し、２次吹込み量を少なくすることを標準とするが、これには限定されない。例えば、１次：２次＝１〜１０：１程度とすることが好ましい。
The third means of the present invention is to transfer the ladle 7 to a gas injection facility after the completion of steeling, and perform secondary blowing of soluble gas into the molten steel in the ladle. As a gas blowing method, if the ladle is capable of top blowing from the immersion lance 9 or bottom blowing, bottom blowing from the
When the soluble gas is secondarily blown, if the stirring is weak and mixing and melting of the slag become insufficient, a mixed gas in which a necessary amount of an inert gas such as argon gas is mixed with the soluble gas may be used.
In the primary and secondary blowing of the soluble gas, it is preferable that the primary blowing amount is preferably blended and the secondary blowing amount be reduced, but the invention is not limited to this. For example, primary: secondary = 1 to about 10: 1 is preferable.
なお、本発明では、上記の処理が終ったら、取鍋７を真空脱ガス装置（図示せず）に搬送し、常法の操業条件で減圧処理を行う。その結果、溶鋼中には微細ガス気泡が発生し、その気泡が溶鋼中に浮遊するとくに微細な介在物をも逃がさず捕捉し、この気泡に帯同した状態で速やかに浮上分離する際に、介在物の効果的な除去が行われる。 In the present invention, after the above process is completed, the ladle 7 is transported to a vacuum degasser (not shown), and a decompression process is performed under normal operating conditions. As a result, fine gas bubbles are generated in the molten steel and trapped without escaping especially the fine inclusions that float in the molten steel. Effective removal of objects is performed.
二次精錬後の溶鋼は、連続鋳造設備や普通造塊設備等の鋳造設備に搬出される。
このような一連の処理を行ったものでは、溶鋼１のスラグ６による再酸化が抑制され、また、溶鋼1中の介在物除去も促進されるため、酸化物系介在物等が極めて少ない高清浄鋼を安定して製造することが可能になる。
The molten steel after the secondary refining is carried out to casting equipment such as continuous casting equipment and ordinary ingot making equipment.
In such a series of treatments, the reoxidation of the
転炉で約２００トンの溶鋼を酸素吹錬し、炭素濃度を０．９〜１．０mass％にした後、窒素ガス３０ｍ3（標準状態）／minを底吹き羽口内から３分間吹き込んだ。
その後、一次精錬溶鋼を取鍋７に出鋼する際に、溶鋼をアルミニウムで脱酸すると同時に、出鋼流にはスラグ改質剤としてＣａＯを１トン添加した。
次に、出鋼終了後、取鍋７を、ガスインジェクション設備に搬送し、ガスインジェクションランスを浸漬して、窒素ガス１０００ ｌ（標準状態）／min、アルゴンガス５００ ｌ（標準状態）／minの混合ガスを４分間吹き込んだ。
About 200 tons of molten steel was oxygen blown in a converter to adjust the carbon concentration to 0.9 to 1.0 mass%, and nitrogen gas 30 m 3 (standard state) / min was blown from the bottom blowing tuyere for 3 minutes.
Thereafter, when the primary refining molten steel was taken out into the ladle 7, the molten steel was deoxidized with aluminum, and at the same time, 1 ton of CaO was added to the outgoing steel flow as a slag modifier.
Next, after the steel is finished, the ladle 7 is transported to the gas injection facility, and the gas injection lance is immersed, and the nitrogen gas is 1000 l (standard state) / min, and the argon gas is 500 l (standard state) / min. The mixed gas was blown for 4 minutes.
その後、前記取鍋７は、ＲＨ真空脱ガス装置に搬送して１４０Ｐａ以下での減圧精錬を４０分間行った後、連続鋳造機にてブルームに鋳造し、ビレット圧延を経て、棒鋼製品とした。清浄度の評価として、酸化物系介在物総量として棒鋼製品中の全酸素量を、また、より有害な介在物に関しては、視野面積３２０ｍｍ2中の酸化物系介在物の最大径によって評価した。 Thereafter, the ladle 7 was conveyed to an RH vacuum degassing apparatus and subjected to reduced pressure refining at 140 Pa or less for 40 minutes, then cast into a bloom with a continuous casting machine, and billet rolled to obtain a steel bar product. As the evaluation of cleanliness, the total amount of oxygen in the steel bar product was evaluated as the total amount of oxide inclusions, and for more harmful inclusions, the maximum diameter of oxide inclusions in a visual field area of 320 mm 2 was evaluated.
また、比較例として、転炉で窒素ガスを吹き込まなかった場合、取鍋へ窒素ガスを吹き込まなかった場合、スラグ改質剤を添加しなかった場合についても、ＲＨ真空脱ガス装置にて減圧精錬を４０分間行った後、連続鋳造機にてブルームに鋳造し、ビレット圧延を経て棒鋼製品とし、棒鋼製品中の全酸素量および酸化物系介在物の最大径を調査した。 Moreover, as a comparative example, when nitrogen gas was not blown in the converter, nitrogen gas was not blown into the ladle, and when no slag modifier was added, RH vacuum degassing equipment was used for refining under reduced pressure. For 40 minutes, cast into bloom with a continuous casting machine, billet-rolled to obtain a steel bar product, and the total amount of oxygen in the steel bar product and the maximum diameter of oxide inclusions were investigated.
表１に各試験における試験条件及び試験結果を示す。また、図２に各製造法における全酸素量を示し、図３には酸化物系介在物の最大径を示す。 Table 1 shows test conditions and test results in each test. FIG. 2 shows the total amount of oxygen in each production method, and FIG. 3 shows the maximum diameter of the oxide inclusions.
表１および図２、図３に示すように、本発明法に従う方法で製造した棒鋼（Ｎｏ．１〜５）は比較例（Ｎｏ．６〜１１）で製造したものより全酸素量は少なく、酸化物系介在物最大径も小さくなっており、鋼の清浄性が向上しているこがわかった。 As shown in Table 1, FIG. 2, and FIG. 3, the steel bars (Nos. 1 to 5) manufactured by the method according to the present invention have less total oxygen than those manufactured in the comparative examples (Nos. 6 to 11). The maximum diameter of oxide inclusions was also reduced, indicating that the cleanliness of the steel was improved.
本発明に係る技術は、鋼の高清浄化方法であるが、例えば、軸受材料や電子材料や半導体製造の如き特殊用途鋼などの分野で必要とされる鋼の高清浄化技術であるが、単にそれだけでなく、他の一般的な高品質の鋼材を製造するのに好適に用いられる。 Although the technology according to the present invention is a high cleaning method for steel, for example, it is a high cleaning technology for steel that is required in the field of special-purpose steel such as bearing materials, electronic materials, and semiconductor manufacturing. Rather, it is suitably used for producing other general high-quality steel materials.
１ 溶鋼
２ 転炉
３ 上吹きランス
４ 底吹き羽口
５ 可溶性ガス発生物質
６ スラグ
７ 取鍋
８ スラグ改質剤
９ 浸漬ランス
１０ 取鍋底吹き羽口
DESCRIPTION OF
Claims (2)
第１段階の処理として、前記可溶性ガスもしくは可溶性ガス発生物質を、転炉精錬中もしくは精錬完了後の段階で吹き込みまたは添加して溶解させ、
第２段階の処理として、転炉からの出鋼時には出鋼流に対してスラグ改質剤を添加し、
第３段階の処理として、真空脱ガス処理に先立つ取鍋内溶鋼中に可溶性ガスを再び単独または不活性ガスとともに吹き込み、
そして、前記可溶性ガスの吹き込みに当たっては、前記転炉精錬中もしくは精錬完了後の段階における１次吹込みと、前記真空脱ガス処理に先立つ取鍋内溶鋼中における段階における２次吹込みとの比率を、１〜１０：１とすることを特徴とする高清浄鋼の製造方法。 During the vacuum degassing treatment of molten steel, the soluble gas is dissolved in the molten steel to be treated in advance, and then the molten steel is decompressed to trap the inclusions in the molten steel by the gas bubbles generated at this time and remove it floating In the manufacturing method of high clean steel
As the first stage treatment, the soluble gas or the soluble gas generating substance is blown or added in the stage during or after converter refining or after completion of refining, and dissolved .
As a second stage treatment , a slag modifier is added to the outgoing steel flow at the time of steel output from the converter,
As the processing of the third stage, viewed write blown with again either alone or in inert gas soluble gas into the ladle in the molten steel prior to the vacuum degassing treatment,
And in blowing the soluble gas, the ratio of the primary blowing in the stage during the converter refining or after completion of the refining and the secondary blowing in the stage in the molten steel in the ladle prior to the vacuum degassing treatment 1 to 10: 1, A method for producing highly clean steel.
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