JPH0696739B2 - Highly clean ultra low carbon steel melting method - Google Patents
Highly clean ultra low carbon steel melting methodInfo
- Publication number
- JPH0696739B2 JPH0696739B2 JP1293984A JP29398489A JPH0696739B2 JP H0696739 B2 JPH0696739 B2 JP H0696739B2 JP 1293984 A JP1293984 A JP 1293984A JP 29398489 A JP29398489 A JP 29398489A JP H0696739 B2 JPH0696739 B2 JP H0696739B2
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- slag
- treatment
- vacuum
- low carbon
- 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.)
- Expired - Lifetime
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Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Description
【発明の詳細な説明】 ＜産業上の利用分野＞ 本発明は転炉等の製鋼炉から出鋼された溶鋼を真空脱ガ
ス装置により脱炭処理して高清浄極低炭素鋼を溶製する
方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention decarburizes the molten steel discharged from a steelmaking furnace such as a converter by a vacuum degassing apparatus to produce highly clean ultra-low carbon steel. It is about the method.
＜従来の技術＞ 周知のように転炉等の製鋼炉（一次精錬炉）においては
Ｃ（炭素）濃度が200ppm程度以下となるまで脱炭するこ
とは技術的に困難である。したがってＣ濃度が200ppm程
度以下の低炭素鋼を得たい場合には、転炉等の一次精錬
炉から出鋼された溶鋼を二次精錬装置である真空脱ガス
装置において減圧雰囲気に曝すことによりＣをCOガスと
して真空脱炭処理する必要がある。<Prior Art> As is well known, it is technically difficult to decarburize a steelmaking furnace such as a converter (primary refining furnace) until the C (carbon) concentration becomes about 200 ppm or less. Therefore, in order to obtain a low carbon steel having a C concentration of about 200 ppm or less, the molten steel discharged from the primary refining furnace such as a converter is exposed to a reduced pressure atmosphere in a vacuum degassing device which is a secondary refining device. It is necessary to carry out vacuum decarburization treatment using CO as CO gas.
このような目的に使用される真空脱ガス装置としては従
来からRH式真空脱ガス装置、DH式真空脱ガス装置、VOD
炉等が知られており、これらのうちRH式真空脱ガス装置
が代表的なものである。Vacuum degassing equipment used for such purposes has traditionally been RH vacuum degassing equipment, DH vacuum degassing equipment, and VOD.
Furnaces and the like are known, and of these, the RH type vacuum degassing apparatus is typical.
ところで、転炉から出鋼時に取鍋に流出するスラグには
転炉の吹錬で形成された高濃度のＴ・Fe（酸化鉄）が、
特に低炭材の場合においてはＣの吹下げがなされるため
10〜20％のＴ・Feが含まれている。この酸化性の高いス
ラグに何も処理を施さないで使用した場合には、溶鋼中
のAlが酸化されてAl2O3を形成し、鋼中にAl2O3系非金属
介在物が増大することになる。By the way, the slag that flows out of the converter into the ladle at the time of tapping is a high concentration of T.Fe (iron oxide) formed by the blowing of the converter.
Especially in the case of low carbon materials, C is blown down.
It contains 10 to 20% T · Fe. When this highly oxidizable slag is used without any treatment, Al in the molten steel is oxidized to form Al 2 O 3 , and Al 2 O 3 -based nonmetallic inclusions increase in the steel. Will be done.
このような問題に対処するため酸化性の高いスラグに還
元剤等を添加して改質することが周知であり、たとえば
特開昭59−70710号公報に「製鋼炉から取鍋へ出鋼した
溶鋼を真空二次精錬するに際し、製鋼炉からの出鋼時に
製品としてほぼ必要量の脱酸剤（Al等）を添加すると共
に、脱酸生成物の合体浮上促進のためのフラックスを添
加し、更に酸化性スラグを改質するためのスラグ還元剤
（Al灰等）を添加する高清浄鋼の製造方法」が提案され
ている。In order to deal with such a problem, it is well known that a highly oxidizing slag is modified by adding a reducing agent or the like. For example, Japanese Patent Laid-Open No. 59-70710 discloses that "steel is taken from a steelmaking furnace to a ladle. At the time of secondary refining of molten steel in vacuum, a deoxidizing agent (Al, etc.) of almost the required amount as a product is added at the time of tapping from a steelmaking furnace, and a flux for promoting floating of coalescence of deoxidized products, Furthermore, a method for producing highly clean steel by adding a slag reducing agent (such as Al ash) for modifying the oxidizing slag has been proposed.
一般に真空脱ガス装置で極低炭素鋼を真空二次精錬によ
り溶製する際には、脱ガス槽内の溶鋼を減圧下で処理す
ることにより、その初期には自己の保有するＣを酸素に
より脱炭する自己脱炭処理が起こり、いわゆるリムド処
理により次第にＣ量が低減する。Generally, when ultra-low carbon steel is smelted by vacuum secondary refining in a vacuum degassing device, the molten steel in the degassing tank is treated under reduced pressure, so that the C held by itself is oxygenated at the beginning. A self-decarburization treatment for decarburization occurs, and the so-called rimmed treatment gradually reduces the amount of C.
かくして、たとえばＣ量が28ppm、Ｏが150ppm程度にな
るが、この段階で脱酸を図るため溶鋼中にAlを添加して
Ｏ量を低減するいわゆるキルド処理を行う。このキルド
処理段階では次工程での溶鋼鋳込時の温度を補償すると
共に脱炭を促進するために脱ガス槽中に酸素ガスを吹込
むことが多いが、この場合には溶鋼が酸化されるのでAl
添加量を更に増加する必要がある。Thus, for example, the amount of C is about 28 ppm and the amount of O is about 150 ppm. At this stage, Al is added to the molten steel to achieve deoxidation.
A so-called killing process for reducing the O amount is performed. In this killing step, oxygen gas is often blown into the degassing tank in order to compensate the temperature during molten steel casting in the next process and accelerate decarburization, but in this case the molten steel is oxidized. So Al
It is necessary to further increase the amount added.
＜発明が解決しようとする課題＞ このように真空脱ガス装置により極低炭素鋼を真空二次
精錬により溶製する際には、リムド処理に続くキルド処
理のためAlを添加するので、前記特開昭59−70710号公
報に提案された従来技術のように真空二次精錬する前の
段階でスラグに還元剤を添加してＴ・Feを低下させる等
の対策を講じただけでは真空二次精錬におけるキルド処
理により発生する多量のAl2O3のために処理終了時の酸
素濃度Ｏのバラツキが大きくなるという問題点があっ
た。<Problems to be Solved by the Invention> When melting ultra-low carbon steel by vacuum secondary refining with a vacuum degassing apparatus as described above, Al is added for killing treatment subsequent to rimming treatment. Just as in the prior art proposed in Japanese Laid-Open Patent Publication No. 59-70710, a secondary vacuum treatment is required only by adding a reducing agent to the slag to reduce T / Fe before the secondary vacuum refining. There is a problem that the oxygen concentration O varies greatly at the end of the treatment due to a large amount of Al 2 O 3 generated by the killing treatment in refining.
本発明は前記従来技術の問題点を解消し、真空脱ガス装
置による真空二次精錬過程でのスラグ改質による高清浄
度極低炭素鋼の真空二次精錬法を提供することを目的と
するものである。SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a vacuum secondary refining method for highly clean ultra-low carbon steel by slag reforming in a vacuum secondary refining process using a vacuum degassing apparatus. It is a thing.
＜課題を解決するための手段＞ 本発明者らがRH真空脱ガス装置でRHキルド処理中のスラ
グを高さ方向に層別してサンプリングし、その成分を分
析した結果、スラグ層の下側は高いAl2O3濃度になって
いることが判明した。これは溶鋼中に形成されたAl2O3
がスラグの下側に吸着されるためで、たとえばスラグの
Al2O3が25％程度であってもスラグの下側は40％程度と
高く、融点が1600℃以上にも上昇し、スラグの下側が固
化する。<Means for Solving the Problems> The inventors of the present invention sampled the slag in the RH killing process in the height direction by the RH vacuum degassing device and analyzed the components, and as a result, the lower side of the slag layer was high. It was found that the concentration was Al 2 O 3 . This is the Al 2 O 3 formed in the molten steel.
Is adsorbed on the lower side of the slag.
Even if Al 2 O 3 is about 25%, the lower side of the slag is as high as about 40%, the melting point rises to over 1600 ° C, and the lower side of the slag solidifies.
かくして、スラグ−メタルの境界は高Al2O3濃度、高融
点層の境界を形成し、Al2O3の吸収能を低下させてい
る。その結果、キルド処理中に溶鋼中に形成されたAl2O
3がスラグに吸収されるのを阻害し、溶鋼中の酸素濃度
が高くなり、そのバラツキを大きくする原因になってい
ることを知見した。Thus, the slag-metal boundary forms a boundary between high Al 2 O 3 concentration and high melting point layers and reduces the absorption capacity of Al 2 O 3 . As a result, Al 2 O formed in the molten steel during the killing process
It was found that 3 inhibits the absorption of slag into the slag, and the oxygen concentration in the molten steel becomes high, which causes the variation to be large.
本発明はキルド処理中にスラグの下側に形成される高Al
2O3層の融点を低下させることによってスラグのAl2O3吸
収能を向上させ、これによってキルド処理した溶鋼中の
酸素を安定して低下させるべく種々実験を重ねた結果に
より達成されたものであり、その要旨とするところは下
記の通りである。The present invention is concerned with the high Al formed underneath the slag during the killing process.
Achieved as a result of various experiments to improve the Al 2 O 3 absorption capacity of slag by lowering the melting point of the 2 O 3 layer and thereby to stably reduce the oxygen in the killed molten steel. The main points are as follows.
本発明は、溶鋼を真空脱ガス装置により真空脱炭処理し
て極低炭素鋼を溶製するに当たり、真空脱炭処理におけ
る溶鋼のリムド処理に続くAl添加によるキルド処理の初
期段階で、真空脱ガス処理中の取鍋内の溶鋼上に浮上し
ているスラグに、溶鋼中に発生する予測Al2O3に対し、C
aOのモル比率がCaO/Al2O3＝0.5〜2.0範囲になるようにC
aOを添加してスラグを改質することを特徴とする高清浄
極低炭素鋼の溶製方法である。The present invention is a vacuum decarburization treatment of molten steel by a vacuum degassing apparatus to produce an ultra-low carbon steel, in the vacuum decarburization treatment, in the initial stage of the killing treatment by the addition of Al following the rimmed treatment of the molten steel, the vacuum decarburization treatment is performed. In the slag floating above the molten steel in the ladle during gas treatment, C against the predicted Al 2 O 3 generated in the molten steel
C so that the molar ratio of aO is CaO / Al 2 O 3 = 0.5-2.0
It is a method for melting highly clean ultra-low carbon steel, characterized in that slag is modified by adding aO.
＜作用＞ 前述の通りリムド処理に続くAl添加によりキルド処理す
ると溶鋼中に多量のAl2O3が発生し、このAl2O3がスラグ
の下側に吸着されスラグ−メタルの境界はAl2O3濃度が
高くなり融点が上昇するのは前述の通りであるが、本発
明では融点の上昇を抑制するためキルド処理の初期段階
でシュートから真空槽内の溶鋼上に投入することによっ
てスラグの下側にCaOを添加してスラグを改質する。<Action> a large amount of Al 2 O 3 occurs in the molten steel when killed treated with Al added followed as described above rimmed processing, the Al 2 O 3 is attracted to the lower side of the slag slag - metal boundaries Al 2 As described above, the O 3 concentration increases and the melting point rises.However, in the present invention, in order to suppress the increase in the melting point, the slag of the slag is introduced by introducing it from the chute onto the molten steel in the initial stage of the killing treatment. Modify the slag by adding CaO to the lower side.
Al2O3−CaO状態図（図示せず）によればAl2O3:CaO＝1:1
のときに最も融点が低いことが周知であるが、本発明で
はAl2O3に対しCaOのモル比率がCaO/Al2O3＝0.5〜2.0の
範囲になるようにCaOを添加することによってスラグの
融点を低下させるものである。その理由はCaO/Al2O3が
0.5未満あるいは2.0を超えるといずれも融点が上昇し、
CaOの添加効果が得られないからである。According to the Al 2 O 3 -CaO phase diagram (not shown), Al 2 O 3 : CaO = 1: 1
By the most possible melting point is low is well known, the molar ratio of CaO to Al 2 O 3 in the present invention is the addition of CaO to be in the range of CaO / Al 2 O 3 = 0.5~2.0 when It lowers the melting point of slag. The reason is CaO / Al 2 O 3
If it is less than 0.5 or more than 2.0, the melting point increases,
This is because the effect of adding CaO cannot be obtained.
好ましくはCaO/Al2O3＝0.7〜1.5の範囲になるようにス
ラグを改質すれば、溶鋼中に発生するAl2O3の吸収率を
さらに向上させることができる。その結果、真空脱ガス
処理後の鋼中酸素が低下され、真空脱炭処理上の種々の
バラツキがあっても確実に高清浄度の極低炭素鋼を溶製
することが可能となる。Preferably, if the slag is modified so that CaO / Al 2 O 3 = 0.7 to 1.5, the absorption rate of Al 2 O 3 generated in the molten steel can be further improved. As a result, the oxygen content in the steel after the vacuum degassing process is reduced, and it becomes possible to surely produce an extremely low carbon steel with high cleanliness even if there are various variations in the vacuum decarburization process.
＜実施例＞ 以下、本発明の一実施例を図面に基づいて説明する。上
底吹き転炉において一次精錬された約250tの溶鋼を取鍋
に出鋼し、第１図に示すRH式真空脱ガス装置を用いて真
空脱炭処理を行った。取鍋６に出鋼したRH処理前の溶鋼
４の成分を第１表に本発明例と従来例とを併せて示して
おり、また、溶鋼４上に浮上している本発明例のスラグ
７の成分を第２表に示している。<Example> Hereinafter, an example of the present invention will be described with reference to the drawings. Approximately 250 tons of molten steel that was primarily refined in the upper-bottom blowing converter was tapped into a ladle, and vacuum decarburization treatment was performed using the RH type vacuum degassing device shown in FIG. Table 1 shows the composition of the molten steel 4 before the RH treatment, which has been tapped in the ladle 6, together with the examples of the present invention and the conventional example, and the slag 7 of the example of the present invention floating on the molten steel 4 is shown. The ingredients of are shown in Table 2.
第１図に示すように取鍋６内に収容された温度1622℃の
前記成分の溶鋼４中に管径550mmφの上昇浸漬管3Aおよ
び下降浸漬管3Bを浸漬させ、真空ポンプ１により脱ガス
槽２内を減圧し、溶鋼４を吸上げる。そして上昇浸漬管
3Aの環流用ガス吹込口５からArガスを1500Nl/min吹込み
ながら取鍋４内と脱ガス槽２との間で溶鋼４を環流させ
る。 As shown in FIG. 1, the ascending dip pipe 3A and the descending dip pipe 3B having a pipe diameter of 550 mmφ are dipped in the molten steel 4 having the above-mentioned composition and stored in the ladle 6 at a temperature of 1622 ° C. The pressure inside 2 is reduced and the molten steel 4 is sucked up. And rising dip tube
The molten steel 4 is circulated between the inside of the ladle 4 and the degassing tank 2 while injecting 1500 Nl / min of Ar gas from the 3 A recirculation gas inlet 5.
脱ガス槽２内を環流する溶鋼４は0.2トール程度の減圧
下に曝され連続的に真空脱炭処理される。かくしてリム
ド処理末期、すなわちRH処理開始から15分経過後に溶鋼
４中のＣが28ppmまた酸素Ｏが150ppmになった段階で次
工程の連続鋳造における鋳込温度を補償するためランス
８から酸素ガスを吹込み、溶鋼４の温度を1628℃に上昇
させた。The molten steel 4 circulating in the degassing tank 2 is exposed to a reduced pressure of about 0.2 Torr and continuously vacuum decarburized. Thus, at the end of the rimming treatment, that is, at the stage where C in the molten steel 4 becomes 28 ppm and oxygen O becomes 150 ppm 15 minutes after the start of RH treatment, oxygen gas is supplied from the lance 8 to compensate the casting temperature in the continuous casting in the next process. Blowing, the temperature of the molten steel 4 was raised to 1628 ° C.
その結果、溶鋼４中のＯは600ppmに急上昇した。そこで
RH処理開始から20分経過後に脱ガス槽２内に0.66kg/tの
Alを添加してキルド処理すると共にシュート９から脱ガ
ス槽２内の溶鋼４上に投入することによって取鍋６内の
溶鋼４上に浮上しているスラグ７の下側に生石灰（Ca
O）を1kg/t添加してスラグ７を改質し、低融点化を図っ
た。As a result, O in the molten steel 4 sharply increased to 600 ppm. Therefore
20 minutes after the start of RH treatment, 0.66 kg / t of degassing tank 2
By adding Al and killing it, and by putting it from the chute 9 onto the molten steel 4 in the degassing tank 2, quick lime (Ca) is added below the slag 7 floating on the molten steel 4 in the ladle 6.
O) was added at 1 kg / t to modify the slag 7 to lower its melting point.
ここでAlを0.66kg添加してキルド処理したのは鋼中Ｏ10
0ppmに対してAlを0.11kg/t添加するのを目安としている
ためである。0.66kg/tのAl添加により溶鋼中に発生する
予測Al2O3量は原子量からAl2O3＝0.66kg/t×1.9＝1.25k
g/tとなる。Here, 0.66 kg of Al was added and the kill treatment was performed in the steel with O 10
This is because the standard is to add 0.11 kg / t of Al to 0 ppm. The predicted amount of Al 2 O 3 generated in molten steel by adding 0.66 kg / t of Al is calculated from the atomic weight of Al 2 O 3 = 0.66 kg / t × 1.9 = 1.25 k
It becomes g / t.
この予測Al2O3量1.25kg/tに対してCaO/Al2O3＝１のモル
比率でCaOを添加する場合、添加CaO量＝1.25×0.7≒0.9
kg/tとなるので歩留りをみてCaOを1kg/t添加した。When CaO is added at a molar ratio of CaO / Al 2 O 3 = 1 with respect to this predicted amount of Al 2 O 3 of 1.25 kg / t, the amount of added CaO is 1.25 × 0.7≈0.9.
Since it is kg / t, CaO was added at 1 kg / t in view of the yield.
かくしてキルド処理により溶鋼４中のＯを脱酸し、発生
したAl2O3を取鍋７内の溶鋼４上に浮上している改質ス
ラグ７に吸着させ、RH処理開始から32分後にキルド処理
を終了した。RH処理後の溶鋼成分およびその代表値を、
本発明例および従来例について第１表に示している。ま
た第２表にはRH処理後の本発明例のスラグ成分を示して
いる。Thus, O in the molten steel 4 is deoxidized by the killing treatment, and the generated Al 2 O 3 is adsorbed by the modified slag 7 floating on the molten steel 4 in the ladle 7, and 32 minutes after the start of the RH treatment, the killing is performed. The processing has ended. The molten steel composition after RH treatment and its typical value are
Table 1 shows examples of the present invention and conventional examples. Further, Table 2 shows the slag components of the examples of the present invention after the RH treatment.
第１表に示すように本発明例によれば従来例に比較して
溶鋼中の酸素が大幅に低減し30ppmに確実に低下させる
ことができ高清浄度極低炭素鋼を溶製することができ
た。第２図はキルド初期段階でCaOを添加する本発明例
と添加しない従来例におけるRH終了後の鋼中Ｏ（ppm）
とスラグ中の（Ｔ・Fe）％の関係を示したものであり、
本発明によればスラグの（Ｔ・Fe）が低下し、鋼中Ｏが
低減される効果のあることが分かる。As shown in Table 1, according to the examples of the present invention, oxygen in the molten steel is greatly reduced and can be reliably reduced to 30 ppm as compared with the conventional example, and high cleanliness ultra low carbon steel can be produced. did it. FIG. 2 shows O (ppm) in steel after completion of RH in the example of the present invention in which CaO was added in the early stage of killing and the conventional example in which CaO was not added.
And (T · Fe)% in slag,
It can be seen that according to the present invention, the (T · Fe) of the slag is reduced and the O in the steel is reduced.
＜発明の効果＞ 以上説明したように本発明によればRH処理のキルド処理
初期段階にスラグ中に添加したCaOによりAl2O3層の融点
が低下される。このためスラグのAl2O3吸収能が向上す
るため鋼中酸素を安定して低下させることができ、高清
浄度鋼の確実な溶製が達成される。<Effects of the Invention> As described above, according to the present invention, the melting point of the Al 2 O 3 layer is lowered by CaO added to the slag at the early stage of the killing treatment of the RH treatment. Therefore, the Al 2 O 3 absorption capacity of the slag is improved, so that oxygen in the steel can be stably reduced, and reliable melting of high-cleanliness steel is achieved.
第１図は本発明の一実施例に係るRH式脱ガス装置を示す
断面図、第２図はRH処理後の鋼中Ｏとスラグ（Ｔ・Fe）
％の関係を本発明と従来とを比較して示すグラフであ
る。 １…真空ポンプ、２…脱ガス槽、 ３…浸漬管、４…溶鋼、 ５…環流用ガス吹込口、６…取鍋、 ７…スラグ、８…ランス、 ９…シュート。FIG. 1 is a cross-sectional view showing an RH type degassing apparatus according to an embodiment of the present invention, and FIG. 2 is O in steel and slag (T / Fe) after RH treatment.
It is a graph which shows the relationship of% comparing the present invention with the conventional. DESCRIPTION OF SYMBOLS 1 ... Vacuum pump, 2 ... Degassing tank, 3 ... Immersion pipe, 4 ... Molten steel, 5 ... Circulation gas inlet, 6 ... Ladle, 7 ... Slag, 8 ... Lance, 9 ... Shoot.
Claims (1)
して極低炭素鋼を溶製するに当たり、真空脱炭処理にお
ける溶鋼のリムド処理に続くAl添加によるキルド処理の
初期段階で、真空脱ガス処理中の取鍋内の溶鋼上に浮上
しているスラグに、溶鋼中に発生する予測Al2O3に対しC
aOのモル比率がCaO/Al2O3＝0.5〜2.0範囲になるようにC
aOを添加してスラグを改質することを特徴とする高清浄
極低炭素鋼の溶製方法。1. A method for vacuum decarburizing molten steel by a vacuum degassing apparatus to produce ultra-low carbon steel, in which vacuum is applied at the initial stage of killing treatment by adding Al following rimming treatment of molten steel in vacuum decarburizing treatment. In the slag floating on the molten steel in the ladle during degassing, C against the predicted Al 2 O 3 generated in the molten steel
C so that the molar ratio of aO is CaO / Al 2 O 3 = 0.5-2.0
A method for smelting a highly clean ultra-low carbon steel, characterized by adding aO to modify slag.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1293984A JPH0696739B2 (en) | 1989-11-14 | 1989-11-14 | Highly clean ultra low carbon steel melting method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1293984A JPH0696739B2 (en) | 1989-11-14 | 1989-11-14 | Highly clean ultra low carbon steel melting method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03158412A JPH03158412A (en) | 1991-07-08 |
| JPH0696739B2 true JPH0696739B2 (en) | 1994-11-30 |
Family
ID=17801745
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1293984A Expired - Lifetime JPH0696739B2 (en) | 1989-11-14 | 1989-11-14 | Highly clean ultra low carbon steel melting method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0696739B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101690727B1 (en) * | 2015-11-12 | 2016-12-28 | (주)에이엠에스 엔지니어링 | Seismic retrofitting structure without an anchor and with no demage of the existing structure |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5337289B2 (en) * | 1973-08-03 | 1978-10-07 | ||
| JPS582575B2 (en) * | 1980-03-25 | 1983-01-17 | 株式会社神戸製鋼所 | Method for refining molten metal |
-
1989
- 1989-11-14 JP JP1293984A patent/JPH0696739B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03158412A (en) | 1991-07-08 |
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