JPS6239205B2 - - Google Patents
Info
- Publication number
- JPS6239205B2 JPS6239205B2 JP57182443A JP18244382A JPS6239205B2 JP S6239205 B2 JPS6239205 B2 JP S6239205B2 JP 57182443 A JP57182443 A JP 57182443A JP 18244382 A JP18244382 A JP 18244382A JP S6239205 B2 JPS6239205 B2 JP S6239205B2
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- steel
- slag
- tapping
- secondary refining
- 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
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 46
- 239000010959 steel Substances 0.000 claims description 46
- 239000002893 slag Substances 0.000 claims description 21
- 238000010079 rubber tapping Methods 0.000 claims description 12
- 238000007670 refining Methods 0.000 claims description 11
- 239000003795 chemical substances by application Substances 0.000 claims description 10
- 239000003638 chemical reducing agent Substances 0.000 claims description 6
- 238000005188 flotation Methods 0.000 claims description 6
- 230000004907 flux Effects 0.000 claims description 5
- 238000009628 steelmaking Methods 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 230000001590 oxidative effect Effects 0.000 claims description 4
- 238000004581 coalescence Methods 0.000 claims description 3
- 238000002407 reforming Methods 0.000 claims 1
- 238000000034 method Methods 0.000 description 12
- 230000008569 process Effects 0.000 description 7
- 239000000203 mixture Substances 0.000 description 6
- 238000003756 stirring Methods 0.000 description 6
- 230000003749 cleanliness Effects 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 229910052717 sulfur Inorganic materials 0.000 description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000007667 floating Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910004261 CaF 2 Inorganic materials 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000005028 tinplate Substances 0.000 description 2
- 238000009849 vacuum degassing Methods 0.000 description 2
- 238000009489 vacuum treatment Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 229910021540 colemanite Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000011086 high cleaning Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000005339 levitation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 238000010405 reoxidation reaction Methods 0.000 description 1
- 235000013619 trace mineral Nutrition 0.000 description 1
- 239000011573 trace mineral Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Description
【発明の詳細な説明】
本発明は高清浄度鋼の製造方法に関するもので
ある。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing high-cleanliness steel.
近年、清浄度鋼の要求が益々高まりつつあるこ
とは周知のとおりであり、かかる清浄度鋼は、一
般に溶鋼を２次精錬する方法により製造されてい
る。 It is well known that the demand for cleanliness steel has been increasing in recent years, and such cleanliness steel is generally manufactured by a method of secondary refining of molten steel.
溶鋼の清浄化のために上記の２次精錬を実施す
る狙いは、主として次のとおりである。 The main purpose of performing the above secondary refining for cleaning molten steel is as follows.
RH、DH式真空脱ガス処理時の撹拌エネルギ
ーを利用して溶鋼中に含有されている微小介在
物の合体浮上を促進する。 The stirring energy during RH and DH vacuum degassing treatment is used to promote the coalescence and flotation of minute inclusions contained in molten steel.
真空下におけるカーボン脱酸（〔Ｃ〕＋〔Ｏ〕
→CO↑）を利用して、Al、Si等の脱酸剤を添
加する時点での溶鋼中の〔Ｏ〕を下げることに
より、脱酸時に生成するAl2O3、SiO2等の介在
物源の生成量を少くする。（この場合、２次精
錬での脱〔Ｃ〕量分だけ転炉吹止め〔Ｃ〕を高
くし、転炉吹止め時点での溶鋼中〔Ｏ〕を低く
抑える方法が採られている）
したがつて上記の２次精錬による効果を最大限
に享受するために、転炉出鋼時には、脱酸剤を投
入しないで未脱酸で出鋼するか投入しても脱酸力
の弱いFe−Mnを少量投入するのが従来の一般的
方法であつた（例えば、特開昭53−16314号公
報、特開昭49−115026号公報、特公昭57−25607
号公報等参照）。 Carbon deoxidation under vacuum ([C] + [O]
→CO↑) is used to lower the [O] in molten steel at the time of adding deoxidizers such as Al and Si, thereby reducing inclusions such as Al 2 O 3 and SiO 2 that are generated during deoxidation. Reduce the amount of source produced. (In this case, the method used is to raise the converter stop [C] by the amount of [C] removed in the secondary refining and keep the [O] in the molten steel low at the time of converter stop.) Therefore, in order to maximize the effects of the above-mentioned secondary refining, when tapping the steel in the converter, it is necessary to either tap the steel undeoxidized without adding a deoxidizing agent, or to use Fe- The conventional general method was to add a small amount of Mn (for example, Japanese Patent Application Laid-Open Nos. 16314-1982, 115026-1970, 25607-1982).
(Refer to the publication number, etc.)
上記工程によつて高清浄度鋼を製造する場合、
Sol〔Al〕50×10-3％程度の高Sol〔Al〕材や、
〔Ｃ〕５×10-2％以上の比較的〔Ｃ〕目標の高い
鋼種の場合はほぼ満足すべき清浄度が得られてい
たが、Sol〔Al〕10〜20×10-3％程度の低Sol
〔Al〕材や、〔Ｃ〕５×10-2％以下の低炭材を溶製
する場合は従来法では十分な溶鋼清浄度が得られ
ないことがわかつた。（第１図及び第２図参照）
その理由は次のとおりである。 When manufacturing high-cleanliness steel by the above process,
Sol[Al] high Sol[Al] material of about 50×10 -3 %,
In the case of steels with a relatively high [C] target of [C] 5×10 -2 % or more, almost satisfactory cleanliness was obtained; Low Sol
It has been found that when melting [Al] material or a low carbon material of [C] 5×10 -2 % or less, sufficient molten steel cleanliness cannot be obtained by the conventional method. (See Figures 1 and 2) The reason is as follows.
(i) 低炭材の場合転炉において〔Ｃ〕吹下げがな
されるため、そのスラグはFeO、MnO濃度の
高い極めて酸化性の高い組成となる。また低
Sol〔Al〕材の場合には脱酸剤の投入量が少な
いためスラグ中のFeO、MnO等は十分な還元
がなされないまま２次精錬後においてもそのま
ま高濃度でスラグ中に残存してしまう。これら
の取鍋スラグ中に残存したFeO、MnOは２次
精錬以後の工程で鋼中の〔Al〕〔Si〕〔Ti〕等
のより酸素親和力の強い元素を徐々に酸化させ
微小介在物を生成させる。(i) In the case of low carbon materials, [C] is blown down in the converter, so the slag has a highly oxidizing composition with high concentrations of FeO and MnO. Also low
In the case of Sol [Al] material, since the amount of deoxidizing agent input is small, FeO, MnO, etc. in the slag are not sufficiently reduced and remain in the slag at a high concentration even after secondary refining. . FeO and MnO remaining in these ladle slags gradually oxidize elements with stronger oxygen affinity, such as [Al], [Si], and [Ti] in the steel in the process after secondary refining, producing minute inclusions. let
(ii) 脱酸材添加後の微小介在物の合体浮上時間が
十分に取れないため溶鋼中に微小介在物が残存
してしまう。(ii) After the addition of the deoxidizing agent, there is not enough floating time for the micro-inclusions to coalesce, resulting in the micro-inclusions remaining in the molten steel.
これに対して撹拌時間を長くすると、温度降
下が大きくなり、その分だけ出鋼温度を高くせ
ねばならず、製鋼炉耐火物の溶損による介在物
の増加を来たすことになる。 On the other hand, if the stirring time is increased, the temperature drop increases, and the tapping temperature must be increased accordingly, which results in an increase in inclusions due to melting of the steelmaking furnace refractories.
(iii) 溶鋼に単に撹拌エネルギーを付与しただけで
は微小介在物の合体浮上効果は十分に得られな
い。(iii) Simply imparting stirring energy to molten steel does not provide a sufficient effect of merging and flotation of minute inclusions.
本発明は上記の難点を除去し、特に低SolAl領
域、低Ｃ領域の溶鋼の高清浄化を図ることを目的
としたものである。 The object of the present invention is to eliminate the above-mentioned difficulties and to achieve high cleaning of molten steel, especially in the low SolAl region and the low C region.
本発明の要旨は製鋼炉から取鍋へ出鋼した溶鋼
を２次精錬するにさいし、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ツク
スを添加し、更に酸化性スラグを改質するための
スラグ還元剤を併用添加することを特徴とする高
清浄度鋼の製造方法にある。 The gist of the present invention is to perform secondary refining of molten steel tapped from a steelmaking furnace into a ladle, to add a deoxidizing agent in an amount almost required for the product at the time of tapping from the steelmaking furnace, and to combine the deoxidized products. A method for manufacturing high-cleanliness steel characterized by adding flux to promote floating and further adding a slag reducing agent to reform oxidizing slag.
すなわち本発明に従つて、出鋼時にAl、Si等の
脱酸剤を添加することにより、
(i) 脱酸生成物を早期に生成させ鋳造までの合
体・浮上時間を確保する。 That is, according to the present invention, by adding a deoxidizing agent such as Al or Si during tapping, (i) deoxidizing products are generated early and the time for coalescence and flotation until casting is secured.
(ii) 出鋼時の温度降下を低減させることにより出
鋼温度を下げ耐火物溶損による介在物源のイン
プツトを少なくする。あるいはまたその温度低
下分だけ２次精錬過程における撹拌時間を延長
することが可能となる。(ii) By reducing the temperature drop during tapping, the tapping temperature is lowered and the input of inclusion sources due to refractory melting is reduced. Alternatively, it becomes possible to extend the stirring time in the secondary refining process by the amount of the temperature drop.
また上記脱酸剤の添加と同時に介在物合体浮
上促進用のフラツクスを投入することにより、
(iii) 出鋼時の撹拌エネルギーにより低融点造滓剤
が溶鋼中に微細に分散しAl2O3、SiO2等の脱酸
生成物同志の合体浮上を促進し、同時に浮上介
在物の吸着吸収剤層を溶鋼表面に形成する。 In addition, by adding flux to promote inclusion flotation at the same time as adding the deoxidizing agent, (iii) the low melting point slag forming agent is finely dispersed in the molten steel by the stirring energy during tapping, and Al 2 O 3 , promotes the merging and flotation of deoxidized products such as SiO 2 , and at the same time forms an adsorbent layer of floating inclusions on the surface of the molten steel.
この様にすることにより、溶鋼中介在物の浮上
促進が著しく促進され、極めて高清浄度の溶鋼が
得られるものである。 By doing so, the levitation of inclusions in the molten steel is significantly promoted, and molten steel of extremely high purity can be obtained.
更に出鋼時の末期に酸化性スラグを改質するた
めのスラグ還元剤を添加するものであり、これに
より、スラグ中のFeO、MnO等の溶鋼汚染源を
還元し、より溶鋼の清浄化を達成するものであ
る。 In addition, a slag reducing agent is added to reform the oxidizing slag at the end of the tapping process, thereby reducing molten steel contamination sources such as FeO and MnO in the slag, thereby achieving further purification of the molten steel. It is something to do.
上記スラグ還元剤を出鋼時に添加することによ
り、出鋼時の撹拌エネルギーを利用して効率よく
スラグの還元を図ることが出来、また２次精錬工
程に入る以前のできるだけ早い時点ですでにスラ
グの改質を完了させておくことにより、スラグに
よる溶鋼再酸化を極小化することができる。溶鋼
脱酸剤の種類としてはAl、Siを始めどのようなも
のでも良い。また脱酸剤出鋼時の投入量について
は、
(i) 溶鋼中の〔Ｏ〕をすべて脱酸してしまう。 By adding the above-mentioned slag reducing agent at the time of tapping, it is possible to efficiently reduce slag using the stirring energy during tapping, and the slag can be reduced as early as possible before entering the secondary refining process. By completing the modification of molten steel, reoxidation of molten steel by slag can be minimized. Any type of molten steel deoxidizer may be used, including Al and Si. Regarding the amount of deoxidizing agent added during tapping, (i) it deoxidizes all [ O ] in the molten steel.
(ii) ２次精錬工程における脱酸、脱炭メリツトを
享受するために150〜200ppm程度の鋼中
〔Ｏ〕を残す。(ii) Approximately 150 to 200 ppm of [ O ] is left in the steel in order to enjoy the benefits of deoxidation and decarburization in the secondary refining process.
等の選択が可能である。更にフラツクス成分と
しては一般に広く知られているCaO−CaF2系を
始めとしてCaO−コレマナイト系、CaO−抗火石
系、CaO−SiO2−Al2O3系あるいはこれらをベー
スとして微量元素としてLi、Al、Mg等の化合物
を少量添加したものが考えられる。一方、スラグ
還元剤としては、例えばAl灰、CaC2、等が好適
である。 It is possible to select the following. Furthermore, flux components include the generally well-known CaO-CaF 2 system, CaO-colemanite system, CaO-anti-flint system, CaO-SiO 2 -Al 2 O 3 system, or based on these, trace elements such as Li, It is possible to add a small amount of a compound such as Al or Mg. On the other hand, suitable examples of the slag reducing agent include Al ash, CaC 2 , and the like.
以下従来例及び本発明実施例を説明する。 A conventional example and an embodiment of the present invention will be described below.
従来例
Ｃ 0.08％、Si trace、Mn 0.14％、Ｐ 0.015
％、Ｓ 0.015％〔Ｏｆ〕450PPM、温度1700℃で
脱酸剤を投入することなしに出鋼した。取鍋内の
スラグ組成を第３図に示す。次に溶鋼をRH式真
空脱ガス処理した。この脱ガス処理時間は12分で
Al投入量は0.4Kg／ｔ−steelであつた。得られた
溶鋼の成分組成は次のとおりである。Conventional example C 0.08%, Si trace, Mn 0.14%, P 0.015
%, S 0.015% [ O f] 450 PPM, and the steel was tapped at a temperature of 1700°C without adding a deoxidizing agent. Figure 3 shows the slag composition in the ladle. Next, the molten steel was subjected to RH vacuum degassing treatment. This degassing process takes 12 minutes.
The Al input amount was 0.4 kg/t-steel. The composition of the obtained molten steel is as follows.
Ｃ 0.04％、Si trace、Mn 0.15％、Ｐ 0.017
％、Ｓ 0.015％、SolAl 0.012％
この溶鋼を周知の方法で連続鋳造、熱間圧延、
冷間圧延等の工程を経てブリキとした。連続鋳造
鋳片のＭ片相当部分から採取した試験片の表面欠
陥状況を第５図に示す。 C 0.04%, Si trace, Mn 0.15%, P 0.017
%, S 0.015%, SolAl 0.012% This molten steel was continuously cast, hot rolled,
It was made into tinplate through processes such as cold rolling. Figure 5 shows the surface defects of a test piece taken from a portion corresponding to the M piece of the continuously cast slab.
本発明例
Ｃ 0.05％、Si trace、Mn 0.14％、Ｐ 0.016
％、Ｓ 0.016％〔Ｏｆ〕560PPM、温度1680℃で
Al1.30Kg／ｔ−steel、フラツクス（CaO：CaF2
＝７：３）５Kg／ｔ−steel及びスラグ還元剤
（Al灰）３Kg／ｔ−steelを投入しながら取鍋に出
鋼した。取鍋内のスラグ組成を第４図に示す。次
にこの溶鋼を、真空処理及びSolAl調整を行つ
た。真空処理時間は10分、Al添加量は0.1Kg／ｔ
−steelであつた。得られた溶鋼の成分組成は次
のとおりである。Invention example C 0.05%, Si trace, Mn 0.14%, P 0.016
%, S 0.016% [ O f] 560PPM, temperature 1680℃
Al1.30Kg/t-steel, flux (CaO:CaF 2
=7:3) Steel was tapped into a ladle while charging 5 kg/t-steel and 3 kg/t-steel of slag reducing agent (Al ash). Figure 4 shows the slag composition in the ladle. Next, this molten steel was subjected to vacuum treatment and SolAl adjustment. Vacuum treatment time is 10 minutes, Al addition amount is 0.1Kg/t
-It was steel. The composition of the obtained molten steel is as follows.
Ｃ 0.04％、Si trace、Mn 0.15％、Ｐ 0.017
％、Ｓ 0.016％、SolAl 0.012％
この溶鋼を従来例と同様に処理してブリキと
し、その試験片の表面欠陥状況を第６図に示す。 C 0.04%, Si trace, Mn 0.15%, P 0.017
%, S 0.016%, SolAl 0.012% This molten steel was processed into tinplate in the same manner as in the conventional example, and the surface defects of the test piece are shown in FIG.
上記第５図及び第６図からも明らかな様に、本
発明方法によれば、成品の表面欠陥を大巾に減少
せしめ得る高清浄度鋼が得られるものであり、品
質向上に大きく寄与するものである。 As is clear from FIGS. 5 and 6 above, according to the method of the present invention, high-cleanliness steel that can greatly reduce surface defects in finished products can be obtained, which greatly contributes to quality improvement. It is something.
第１図及び第２図は成品SolAlレベル及び成品
Ｃレベルと介在物品質との関係を示す図表、第３
図及び第４図は従来例及び本発明実施例における
取鍋内スラグ組成を示す図表、第５図及び第６図
は従来例及び本発明実施例により得られた成品の
表面品質指数を示す図表である。
Figures 1 and 2 are charts showing the relationship between the SolAl level of the finished product, the C level of the finished product, and the quality of inclusions.
4 and 4 are charts showing the slag composition in the ladle in the conventional example and the example of the present invention, and FIGS. 5 and 6 are charts showing the surface quality index of the products obtained by the conventional example and the example of the present invention. It is.
Claims (1)
るにさいし、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ツクスを添加し、更
に酸化性スラグを改質するためのスラグ還元剤を
併用添加することを特徴とする高清浄度鋼の製造
方法。1. When performing secondary refining of molten steel tapped from a steelmaking furnace into a ladle, approximately the amount of deoxidizing agent required for the product is added at the time of tapping from the steelmaking furnace, and in order to promote the coalescence and flotation of the deoxidized products. 1. A method for producing high-cleanliness steel, which comprises adding a flux of 100% and a slag reducing agent for reforming oxidizing slag.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18244382A JPS5970710A (en) | 1982-10-18 | 1982-10-18 | Production of highly clean steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18244382A JPS5970710A (en) | 1982-10-18 | 1982-10-18 | Production of highly clean steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5970710A JPS5970710A (en) | 1984-04-21 |
| JPS6239205B2 true JPS6239205B2 (en) | 1987-08-21 |
Family
ID=16118352
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18244382A Granted JPS5970710A (en) | 1982-10-18 | 1982-10-18 | Production of highly clean steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5970710A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01294817A (en) * | 1988-05-23 | 1989-11-28 | Kawasaki Steel Corp | Method for cleaning molten metal |
| JP2575827B2 (en) * | 1988-07-18 | 1997-01-29 | 川崎製鉄株式会社 | Manufacturing method of ultra low carbon steel for continuous casting with excellent cleanliness |
| TWI486454B (en) * | 2012-03-19 | 2015-06-01 | Jfe Steel Corp | Steel manufacturing method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5643367A (en) * | 1979-09-18 | 1981-04-22 | Seiko Epson Corp | Anti-fogging resin coating composition |
| JPS57134525A (en) * | 1981-02-12 | 1982-08-19 | Yoshida Tekkosho:Kk | Adding method for additive to molten metal |
-
1982
- 1982-10-18 JP JP18244382A patent/JPS5970710A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5643367A (en) * | 1979-09-18 | 1981-04-22 | Seiko Epson Corp | Anti-fogging resin coating composition |
| JPS57134525A (en) * | 1981-02-12 | 1982-08-19 | Yoshida Tekkosho:Kk | Adding method for additive to molten metal |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5970710A (en) | 1984-04-21 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2575827B2 (en) | Manufacturing method of ultra low carbon steel for continuous casting with excellent cleanliness | |
| JP5386825B2 (en) | Method for melting Mn-containing ultra-low carbon steel | |
| JP3428628B2 (en) | Stainless steel desulfurization refining method | |
| JP2004169147A (en) | Refining process for clean steel containing extremely low amount of non-metallic inclusion | |
| JP3510989B2 (en) | Refining method of Si alloy iron and stainless steel used for refining stainless steel | |
| JPS6239205B2 (en) | ||
| JP2947063B2 (en) | Stainless steel manufacturing method | |
| JPH0488111A (en) | Method for producing dead soft steel | |
| JPH10140227A (en) | Production of high alloy steel by joining two molten steels | |
| JPH09235611A (en) | Production of extra-low sulfur pure iron having high cleanliness | |
| JPH0472009A (en) | Method for refining high cleanliness steel | |
| JP3220233B2 (en) | Refining method of ultra-low carbon / ultra low sulfur chromium-containing molten steel | |
| JP3158912B2 (en) | Stainless steel refining method | |
| KR100267271B1 (en) | The manufacturing method of low carbon steel with high purity | |
| JP2002030330A (en) | Method for heating molten steel in vacuum refining furnace | |
| JP2855333B2 (en) | Modification method of molten steel slag | |
| JPH04268012A (en) | Production of clean steel | |
| JP2855334B2 (en) | Modification method of molten steel slag | |
| US2049091A (en) | Manufacture of metallic alloys | |
| JPH07316631A (en) | Deoxidizing and cleaning method of molten steel | |
| US1508083A (en) | Manufacture of steel | |
| JP3820686B2 (en) | Melting method of low nitrogen stainless steel | |
| JP2764339B2 (en) | Method of treating hot metal for high chromium low P low S steel | |
| JP2022027515A (en) | Method for desulfurizing molten steel and desulfurization flux | |
| JPH0649524A (en) | Production of highly clean steel |