JPH03153814A - Smelting method for dead soft, extra-low nitrogen high chromium steel - Google Patents
Smelting method for dead soft, extra-low nitrogen high chromium steelInfo
- Publication number
- JPH03153814A JPH03153814A JP29132989A JP29132989A JPH03153814A JP H03153814 A JPH03153814 A JP H03153814A JP 29132989 A JP29132989 A JP 29132989A JP 29132989 A JP29132989 A JP 29132989A JP H03153814 A JPH03153814 A JP H03153814A
- Authority
- JP
- Japan
- Prior art keywords
- vacuum
- decarburization
- steel
- pig iron
- high chromium
- 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
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 22
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 13
- 229910001220 stainless steel Inorganic materials 0.000 title claims description 12
- 238000000034 method Methods 0.000 title description 11
- 238000003723 Smelting Methods 0.000 title 1
- 238000007670 refining Methods 0.000 claims abstract description 22
- 239000007789 gas Substances 0.000 claims abstract description 21
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 10
- 239000001301 oxygen Substances 0.000 claims abstract description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 9
- 239000007787 solid Substances 0.000 claims abstract description 3
- 238000007664 blowing Methods 0.000 claims description 10
- 239000011651 chromium Substances 0.000 claims description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 230000001590 oxidative effect Effects 0.000 claims description 3
- 238000007872 degassing Methods 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 238000005261 decarburization Methods 0.000 abstract description 29
- 229910000831 Steel Inorganic materials 0.000 abstract description 22
- 239000010959 steel Substances 0.000 abstract description 22
- 229910000805 Pig iron Inorganic materials 0.000 abstract 4
- 230000001105 regulatory effect Effects 0.000 abstract 2
- 238000009849 vacuum degassing Methods 0.000 abstract 1
- 238000003756 stirring Methods 0.000 description 8
- 229910052804 chromium Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000010079 rubber tapping Methods 0.000 description 5
- 239000002893 slag Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 238000009489 vacuum treatment Methods 0.000 description 2
- 241000238557 Decapoda Species 0.000 description 1
- 229910005347 FeSi Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 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、超極低炭素・窒素高クロム鋼、特にＣ≦６０
ｐｐｍ、 ｐＪ≦８０ｐｐ−の非常に溶製困難な鋼の溶
製方法に関するものである。[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to ultra-low carbon/nitrogen high chromium steel, especially C≦60
The present invention relates to a method for melting steel, which is extremely difficult to melt and has a pJ≦80 ppm.
〈従来の技術〉
高クロム鋼の製造においては、溶鋼中のクロムによって
、溶鋼中のＣ及びＮの活量が低減されるため、炭素及び
窒素を低下させることは、普通鋼の場合と比較し、極め
て困難である。<Prior art> In the production of high chromium steel, the activities of C and N in molten steel are reduced by chromium in the molten steel, so it is difficult to reduce carbon and nitrogen compared to the case of ordinary steel. , is extremely difficult.
Ｃ≦６０ｐｐｍ、 ｐＪ≦８０ｐｐ−の極低炭素・極低
窒素高クロム鋼を工業的に大量生産する方法としては、
例えば特開昭５３−９４２１２号公報に開示された技術
が知られている。しかし、この方法は３ＯＣｒｔｌ鋼に
おける第２図に示すような関係から、真空脱炭中に十分
なＮの低減を達成するために真空精錬開始時点のＣ濃度
を０．８〜２．５重量％（以下％と略す）に規定してい
る。また、特開昭６０−２６６６１号公報に開示された
技術では真空精錬開始時点のＣ濃度が０．３０％とかな
り低減されているものの、予備脱炭後のＮ濃度を８５〜
９１ｐｐ−と極めて低い値に抑えられている。As a method for industrially mass producing ultra-low carbon, ultra-low nitrogen, high chromium steel with C≦60ppm and pJ≦80pp-,
For example, a technique disclosed in Japanese Unexamined Patent Publication No. 53-94212 is known. However, due to the relationship shown in Figure 2 for 3OCrtl steel, this method requires a carbon concentration of 0.8 to 2.5% by weight at the start of vacuum refining in order to achieve a sufficient reduction of N during vacuum decarburization. (hereinafter abbreviated as %). Furthermore, in the technology disclosed in JP-A No. 60-26661, although the C concentration at the start of vacuum refining is considerably reduced to 0.30%, the N concentration after preliminary decarburization is reduced to 85%.
It is suppressed to an extremely low value of 91 pp-.
一般に真空精錬中の脱窒量は、脱炭量が大きいほど、真
空度が高いほど、さらには攪拌力が強いほど大きくなる
ことが知られている。しかし、脱炭量を大きくとり、例
えば処理前Ｃを０．８０％以上とすれば、真空精錬前の
Ｎが２５０〜３００ｐｐ−程度の高Ｎレベルからでも安
定してＮ≦８０ｐｐｍの高クロム鋼が製造出来るものの
、脱炭に際しては、酸素の供給量と脱炭速度がほぼ比例
するため、脱炭速度を大きくしようとして、酸素の供給
量を増加した場合、排ガス量が増大し、真空系の排気能
力は設備仕様で限定されるために、真空度が悪化して脱
炭中のクロムの酸化が進行する欠点がある。It is generally known that the amount of denitrification during vacuum refining increases as the amount of decarburization increases, the degree of vacuum increases, and the stirring force increases. However, if the amount of decarburization is increased, for example, the C before treatment is set to 0.80% or more, high chromium steel with stable N≦80 ppm even from a high N level of 250 to 300 pp- before vacuum refining can be produced. However, during decarburization, the amount of oxygen supplied and the rate of decarburization are almost proportional, so if you increase the amount of oxygen supplied to increase the decarburization rate, the amount of exhaust gas will increase and the vacuum system will Since the exhaust capacity is limited by equipment specifications, there is a drawback that the degree of vacuum deteriorates and oxidation of chromium progresses during decarburization.
また、攪拌力を上げるには、この酸素の供給速度を大き
くすることや、攪拌用＾ｒガスの吹込速度を上げること
が考えられるが、これも同様に真空度の低下の他、スプ
ラッシュの著しい増大や激しいボイリングによる溶鋼の
飛散が発生し、小止りの低下や設備の損傷、耐火物の…
耗の著しい増大を招き昌い、従って、実際的に、真空精
錬前のＣ濃度を０．８０％以上にすると、第３図に示す
ように脱炭時間がいたずらに増大し、真空処理時間延長
による著しい生産性の低下を招（。In addition, in order to increase the stirring power, it is possible to increase the supply rate of this oxygen or increase the blowing rate of the stirring gas, but this also reduces the degree of vacuum and causes significant splashing. Splashing of molten steel due to boiling and intense boiling may cause a drop in the stop, damage to equipment, and damage to refractories...
Therefore, in practice, if the C concentration before vacuum refining is set to 0.80% or more, the decarburization time will increase unnecessarily, as shown in Figure 3, and the vacuum treatment time will be extended. This can lead to a significant drop in productivity.
さらに、真空精錬の処理前Ｃ６度を高くすると、脱炭中
の溶鋼のボイリングが激しく、取鍋上端からの浴出を防
止するために取鍋のフリーボードを１．５〜２．Ｏｍ近
（取る必要があり、これも処理ヒートサイズを小さくし
生産性を阻害する原因となっていた。Furthermore, if the C6 degree before the vacuum refining process is increased, the boiling of the molten steel during decarburization will be intense, and the free board of the ladle will be set at 1.5~2. It was necessary to take a temperature close to 0.0m, which also reduced the processing heat size and hindered productivity.
真空精錬処理の処理前Ｃを低下させることは生産性の向
上の面から有効ではあるが、それに伴って処理中の脱窒
量が低下するため、粗脱炭後のＮ濃度を低く保つ必要が
生じる。そしてこれを実現するためには、粗脱炭炉にお
ける予備脱炭後に未還元出鋼をしたり、出鋼時の静ガス
やＣＯオガスによる出鋼流のシールといった吸窒の防止
、高価なＡｒを多量に使用した一次希釈吹錬の実施が不
可欠となり、いずれにしても、技術上かつコスト上極め
て不利となる。Although it is effective to reduce C before vacuum refining treatment from the perspective of improving productivity, the amount of denitrification during treatment decreases, so it is necessary to keep the N concentration after rough decarburization low. arise. In order to achieve this, it is necessary to perform unreduced steel extraction after preliminary decarburization in a crude decarburization furnace, to prevent nitrification by sealing the tapping flow with static gas or CO gas during tapping, and to prevent nitrification by sealing the tapping flow with static gas or CO gas during tapping. It is essential to carry out primary dilution blowing using a large amount of sulfur, which is extremely disadvantageous from a technical and cost standpoint.
〈発明が解決しようとする課題〉
本発明は、前述のような現状に鑑み、２次精録処理前の
Ｃ濃度を低く押さえられ、２次精錬時間が短縮でき、生
産性が高い極低炭素・極低窒素高クロム鋼の溶製方法を
提供するためになされたものである。<Problems to be Solved by the Invention> In view of the above-mentioned current situation, the present invention aims to provide an extremely low carbon material that can suppress the C concentration before the secondary refining treatment, shorten the secondary refining time, and has high productivity.・This was done to provide a method for producing ultra-low nitrogen, high chromium steel.
く課題を解決するための手段〉
本発明は、含Ｃｒ溶銑を、浴面下からのガス吹き込み機
能を有する転炉で、Ｃを０．０３重置部〜０．１５重量
％に粗脱炭した後、真空取鍋脱ガス精錬装置へ移し、ま
ず、真空下でＣを６０ｐｐ−以下に脱炭した後にＡｌお
よび／またはＴ１を２重量％以上添加して、Ｎを８０ｐ
ｐｍ以下まで脱窒し、次いで、真空下で気体酸素や固体
酸素によってＡｌ又はＴＩを残存含有量目標値まで酸化
除去した後、成分調整することを特徴とする極低炭素・
極低窒素高クロム鋼の溶製方法である。Means for Solving the Problems> The present invention provides rough decarburization of Cr-containing hot metal to 0.03 to 0.15% by weight of C in a converter having a function of blowing gas from below the bath surface. After that, it is transferred to a vacuum ladle degassing refining equipment, and first, after decarburizing C to 60pp- or less under vacuum, Al and/or T1 is added at 2% by weight or more, and N is reduced to 80pp-
Ultra-low carbon, which is characterized by denitrifying to below pm, then oxidizing and removing Al or TI to the target residual content using gaseous oxygen or solid oxygen under vacuum, and then adjusting the composition.
This is a method for producing ultra-low nitrogen, high chromium steel.
く作用〉
本発明では、高クロム鋼中ではＮの活量が低下するもの
の、Ｎと親和力が極めて強く、かつ比較的安価なＡＩ！
およびもしくはＴ１などの元素を利用し、それを高クロ
ム鋼中に多量に添加し、溶鋼中のＮをこれらの元素との
化合物ＡｎおよびもしくはＴｉＮとして除去したのちに
、その元素を残存含有量目標値まで酸化除去する。In the present invention, although the activity of N decreases in high chromium steel, AI has an extremely strong affinity for N and is relatively inexpensive!
Using elements such as and or T1, adding them in large amounts to high chromium steel, and removing N in the molten steel as compounds An and or TiN with these elements, the elements are added to the residual content target. Oxidize and remove up to the value.
通常の１８Ｃｒ−８Ｎｉオーステナイト系ステンレス鋼
５ＵＳ３０４にＡｌ又はＴＩを≦２００ｔｏｒｒ以下の
真空下で底吹Ａｒガスで攪拌しながら１％から５％まで
添加し、５分後に得られた溶鋼中Ｎ値を第１図に示した
。この場合添加前のＮ濃度は、２００〜５００ｐＰ−の
レベルであった。即ち、これらの元素を合計で一定（１
（２％）以上添加することによって、添加前のＮがかな
り高い値を示していても安定してＮ≦８０ｐｐ−の超極
低窒素高クロム溶鋼を得ることができた。Al or TI is added from 1% to 5% to ordinary 18Cr-8Ni austenitic stainless steel 5US304 under a vacuum of ≦200 torr or less while stirring with bottom-blown Ar gas, and after 5 minutes, the N value in the molten steel obtained is It is shown in Figure 1. In this case, the N concentration before addition was at a level of 200-500 pP-. In other words, if the total of these elements is constant (1
(2%) or more, it was possible to stably obtain ultra-low nitrogen, high chromium molten steel with N≦80 pp− even though the N content before addition was quite high.
その後、２００ｔｏｒｒ以下に保った状態でＡｉ！、や
Ｔｉを酸化除去しても吸窒は殆んど発生せず、充分低い
値に留まることを１ｉ１１認し、この現象を超極低炭素
・窒素高クロム鋼の溶製に適用できれば、生産性が大い
に向上することを見いだした。After that, while keeping the pressure below 200 torr, Ai! 1i11 It has been confirmed that even when oxidation and removal of Ti and Ti is carried out, almost no nitrogen absorption occurs, and the value remains sufficiently low. If this phenomenon can be applied to the melting of ultra-low carbon, high nitrogen, high chromium steel, production will be improved. I found that the performance was greatly improved.
すなわち、Ａ２やＴｉのようにＮやＯと親和力の強い元
素を大量に添加すると、鋼中のＮが＾ｆｆ１ＮやＴｉＮ
の化合物を生成し浮上するため、鋼中Ｎを除去するとい
う性質を用いると、処理前Ｎ１度が高くかつ処理前０６
度が低くて、脱炭に伴う脱Ｎがあまり期待できなく、ま
たＣ≦６０ｐｐ■のレベルでＮが２００〜５００ｐｐ−
と高（でも、２％以上のｈｌおよびもしくはＴｉを添加
すると安定してＮ≦８０ｐｐｓ＋が達成できる。その後
真空下で酸素吹精しかつ温度調整のために鉄鉱石やＣｒ
絋鉱を添加し、目標成分までｈｌやＴｉを酸化除去すれ
ばＣ≦６０１）Ｇｌ−でかつＮ≦８０ｐｐ−の高クロム
鋼の溶製が短時間で能率良く溶製できる。In other words, when a large amount of elements such as A2 and Ti that have a strong affinity with N and O are added, the N in the steel becomes ^ff1N and TiN.
If you use the property of removing N in steel, the N1 degree before treatment is high and the
Since the degree of carbonization is low, it is difficult to expect much deNization due to decarburization, and at the level of C≦60pp■, N is 200 to 500pp-
(However, by adding 2% or more of HL and/or Ti, N≦80pps+ can be stably achieved. After that, oxygen is blown under vacuum and iron ore or Cr is added to adjust the temperature.)
By adding silica and oxidizing and removing hl and Ti to the target components, high chromium steel with C≦601)Gl− and N≦80pp− can be produced efficiently in a short time.
粗脱炭後のＣ濃度の上限を０．１５％としたのは、これ
以上高（しては、２次精錬時の処理時間短縮効果が得ら
れないためと、脱炭中のスプラッシュが大きいためであ
る。下限を０．０３％としたのは、これ以下に粗脱炭し
ても、その際のＣｒ酸化量がＣの低下と共に指数関数的
に増大し、その還元剤のＰｅ５ｔ等の使用量が増して経
済的にメリットが少ない上に、処理時間短縮効果も少な
くなるためである。また粗脱炭にもかなりの時間がかか
るので、２次精錬よりもむしろ粗脱炭の方が全体の生産
性を律速することにもなりかねない。The reason why we set the upper limit of the C concentration after crude decarburization to 0.15% is because if it is higher than this, the effect of shortening the processing time during secondary refining cannot be obtained, and because the splash during decarburization is large. The reason why the lower limit was set at 0.03% is that even if rough decarburization is performed below this level, the amount of oxidized Cr will increase exponentially with the decrease in C, and the reduction agent Pe5t etc. This is because the amount used increases and there is little economic benefit, and the effect of reducing processing time is also reduced.Also, rough decarburization takes a considerable amount of time, so rough decarburization is preferable to secondary refining. It may also become a rate-limiting factor for overall productivity.
２次精錬にて脱炭を実施する前にＡ１やＴｉを大量に添
加し、説窒することも考えられるが、この場合は酸素吹
精を行なって脱炭が開始される前にＡ ｆｆｉ ｇｏｓ
やｙｔｏ＊が大量に生成し、極めて高融点のスラグが溶
鋼上に大量に生成する。したがって、そのままでは脱炭
が進行せず、−旦処理を中断して、スラグオフをする必
要があり生産性に害となるためである。It is also possible to add a large amount of A1 or Ti to nitrify the steel before decarburizing in the secondary refining, but in this case, oxygen blowing is performed and the Affi gos
A large amount of slag and yto* are produced, and a large amount of slag with an extremely high melting point is produced on the molten steel. Therefore, decarburization does not proceed as it is, and it is necessary to interrupt the treatment and remove the slag, which is detrimental to productivity.
また、ｈｌやＴｉを脱炭前に添加するのは、脱炭のため
に、−旦その全てを酸化除去する必要がある点でも不利
である。Adding hl and Ti before decarburization is also disadvantageous in that it is necessary to remove all of them by oxidation for decarburization.
浴面下よりのガス吹き込み機能を有する転炉で粗脱炭す
る理由は、この様な機能がないと攪拌力が弱いために一
次脱炭時のＣｒ酸化量が著しく増大する他、酸化クロム
のＦｅＳｉ等による還元回収の費用が高くつきＣを０．
１５％以下へ低下する上で経済的でないためである。The reason why rough decarburization is performed in a converter that has a function of blowing gas from below the bath surface is that without such a function, the stirring power is weak, which significantly increases the amount of Cr oxidation during the primary decarburization, and the amount of chromium oxide increases. Due to the high cost of reduction and recovery using FeSi etc., C was reduced to 0.
This is because it is not economical to reduce it to 15% or less.
〈実施例〉
転炉で粗脱炭した溶鋼１００ｔｏｎを取鍋に出鋼し、Ｖ
ＯＤ法にて真空精錬処理するプロセスで本発明方法を実
施した。このときの成分、温度の変化を第１表に示す、
ＣＯ，０９３％まで一次脱戻した３０％Ｃｒ溶鋼の出
鋼中にｈｌ １．Ｏｋｇ／Ｌを添加しつつこの溶鋼は取
鍋に受入れ、取鍋中スラグを除去後、ＶＯＤｌ［の真空
タンク内へ取鍋を入れた。<Example> 100 tons of molten steel roughly decarburized in a converter was tapped into a ladle, and V
The method of the present invention was carried out in a vacuum refining process using the OD method. The components and temperature changes at this time are shown in Table 1.
During tapping of 30% Cr molten steel which has undergone primary desorption to 93% CO, hl 1. This molten steel was received in a ladle while adding 0 kg/L, and after removing the slag in the ladle, the ladle was placed in a vacuum tank of VODl.
最初ＡＪ！ ３５０ｋｇ、 ＣａＯ１０００ｋｇを取鍋
中溶鋼に投入し、取鍋底のノズルよりＡｒガスを１８０
０４！ ７分の流量で吹込みながら、上吹き０８ガスを
５ＯＮｎｆ／分の流量で吹込み、２３ ｔｏｒｒの真空
下で吹精し、６分後Ａｌが全て燃焼した段階で、０．ガ
ス流量を７ＮＭＺ分まで低下させ、２４ＯＮｒｒｒを、
吹精すると共に、この間ＦｅＭｏ （Ｍｏ６２％）を１
５００ｋｇ添加し成分調整し、Ｃを９０ＰＰｍまで脱炭
した。なお、この時の真空度は１．７ｔｏｒｒであった
。Ｃが９０ｐｐ−となった時点で上吹き０□ガス吹精を
ストップし、底吹Ａｒガス８００４！／分で１０分間溶
鋼とスラグを撹拌した。First AJ! 350 kg and 1000 kg of CaO were put into the molten steel in a ladle, and 180 kg of Ar gas was added from the nozzle at the bottom of the ladle.
04! While blowing at a flow rate of 7 minutes, top-blown 08 gas was blown in at a flow rate of 5 ONnf/minute, and the ejaculate was blown under a vacuum of 23 torr. After 6 minutes, when all the Al was burned, the gas was 0. Decrease the gas flow rate to 7NMZ, 24ONrrr,
While ejaculating, 1 FeMo (Mo62%) was added during this time.
500 kg was added, the components were adjusted, and C was decarburized to 90 PPm. Note that the degree of vacuum at this time was 1.7 torr. When C reaches 90 pp-, stop top blowing 0□ gas blowing, and bottom blow Ar gas 8004! The molten steel and slag were stirred for 10 minutes at a speed of 1/min.
これによりＣが≦６０ｐｐ−となったのを確認後真空下
でＡｉを３％まで添加し、５分間攪拌を続けた。そして
真空度は２００ ｔｏｒｒに調整した。Ａ２を添加した
ことにより、Ｎが６０ＧＩＰ−以下となったことを確認
した後、０８ガスを６ＯＮｒｒｆ／分で２分間吹精する
と共に、Ｃｒｔｉ石（Ｃｒａｂｓ ４６．５％＋ Ｆｆ
３ｘＯｓ ３０．０％、 ＾ｊ！諺Ｏｓ １４．９％、
ＭｇＯ９，１％）をこの間１１．８ｔｏｎ添加し、底吹
＾ｒガス流量１８００ ｆｆｉ ７分で２０分間攪拌し
所期の目標成分、温度を得ることができた。After confirming that C was ≦60 pp-, Ai was added to 3% under vacuum, and stirring was continued for 5 minutes. The degree of vacuum was adjusted to 200 torr. After confirming that N was 60GIP- or less by adding A2, 08 gas was blown at 6ONrrf/min for 2 minutes, and Crti stone (Crabs 46.5% + Ff
3xOs 30.0%, ^j! Proverb Os 14.9%,
During this period, 11.8 tons of MgO (9.1%) was added and stirred for 20 minutes at a bottom blowing gas flow rate of 1800 ffi for 7 minutes to obtain the desired target components and temperature.
２次精錬時間は特開昭５３−９４２１２号公報開示の従
来方法では平均２４０分であったが本発明方法では約７
８分と大幅に短縮された。The average secondary refining time was 240 minutes in the conventional method disclosed in JP-A-53-94212, but it was approximately 7 minutes in the method of the present invention.
The time was significantly shortened to 8 minutes.
〈発明の効果〉
本発明方法によると、２次精錬時間が大幅に短縮され生
産性の著しい向上につながり、また２次精錬の処理前Ｃ
濃度を低く抑えられ、脱炭中のスプラッシュの問題がな
く、同一容量の取鍋に対しヒートサイズを従来法の６０
ｔｏｎから１０５ｔｏｎまで上げることができ、生産
性の著しい向上につながった。<Effects of the Invention> According to the method of the present invention, the secondary refining time is significantly shortened, leading to a remarkable improvement in productivity, and the C
The concentration can be kept low, there is no splash problem during decarburization, and the heat size is lower than that of the conventional method for the same capacity ladle.
It was possible to increase the production capacity from 105 tons to 105 tons, leading to a significant improvement in productivity.
第１図は真空下での５１１５３０４に於けるＡｌまたは
丁１添加量と添加後５分間Ａｒガス攪拌処理したあとの
Ｎ濃度との関係を示す特性図、第２図は３０％Ｃｒ綱に
おける真空精錬前Ｃ濃度と脱炭後Ｎとの関係を示す特性
図、第３図は１６〜３０％Ｃｒ鋼に於ける真空ｔ＃錬面
前ＣＮ４度真空処理時間との関係を示す特性図である。Figure 1 is a characteristic diagram showing the relationship between the amount of Al or 1 added in 5115304 under vacuum and the N concentration after 5 minutes of Ar gas stirring treatment after addition, and Figure 2 is a characteristic diagram showing the relationship between the amount of Al or 1 added in 5115304 under vacuum, and the N concentration after 5 minutes of Ar gas stirring treatment after addition. FIG. 3 is a characteristic diagram showing the relationship between C concentration before refining and N after decarburization, and FIG. 3 is a characteristic diagram showing the relationship between vacuum t# and CN4 degree vacuum treatment time before refining surface in 16-30% Cr steel.
Claims (1)
る転炉で、Ｃを０．０３重量％〜０．１５重量％に粗脱
炭した後、真空取鍋脱ガス精錬装置へ移し、まず、真空
下でＣを６０ｐｐｍ以下に脱炭した後にＡｌおよび／ま
たはＴｉを２重量％以上添加して、Ｎを８０ｐｐｍ以下
まで脱窒し、次いで、真空下で気体酸素や固体酸素によ
ってＡｌまたはＴｉを残存含有量目標値まで酸化除去し
た後、成分調整することを特徴とする極低炭素・極低窒
素高クロム鋼の溶製方法。The Cr-containing hot metal is roughly decarburized to 0.03% to 0.15% by weight of C in a converter that has a function of blowing gas from below the bath surface, and then transferred to a vacuum ladle degassing refining equipment. After decarburizing C to 60 ppm or less under vacuum, add 2% by weight or more of Al and/or Ti to denitrify N to 80 ppm or less, then decarburize Al or Ti with gaseous oxygen or solid oxygen under vacuum. A method for producing ultra-low carbon, ultra-low nitrogen, high chromium steel, which comprises adjusting the composition after oxidizing and removing the remaining content to a target value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29132989A JPH03153814A (en) | 1989-11-10 | 1989-11-10 | Smelting method for dead soft, extra-low nitrogen high chromium steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29132989A JPH03153814A (en) | 1989-11-10 | 1989-11-10 | Smelting method for dead soft, extra-low nitrogen high chromium steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03153814A true JPH03153814A (en) | 1991-07-01 |
Family
ID=17767504
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29132989A Pending JPH03153814A (en) | 1989-11-10 | 1989-11-10 | Smelting method for dead soft, extra-low nitrogen high chromium steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03153814A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003089815A (en) * | 2001-09-14 | 2003-03-28 | Nisshin Steel Co Ltd | METHOD FOR MANUFACTURING HIGH-PURITY Fe-Cr ALLOY AND Fe-Cr-Ni ALLOY |
| WO2007091700A1 (en) * | 2006-02-09 | 2007-08-16 | Jfe Steel Corporation | Method of denitrifying molten steel |
-
1989
- 1989-11-10 JP JP29132989A patent/JPH03153814A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003089815A (en) * | 2001-09-14 | 2003-03-28 | Nisshin Steel Co Ltd | METHOD FOR MANUFACTURING HIGH-PURITY Fe-Cr ALLOY AND Fe-Cr-Ni ALLOY |
| WO2007091700A1 (en) * | 2006-02-09 | 2007-08-16 | Jfe Steel Corporation | Method of denitrifying molten steel |
| US7901482B2 (en) | 2006-02-09 | 2011-03-08 | Jfe Steel Corporation | Removal method of nitrogen in molten steel |
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