JPH062896B2 - Denitrification of molten steel with rare earth metals - Google Patents
Denitrification of molten steel with rare earth metalsInfo
- Publication number
- JPH062896B2 JPH062896B2 JP770987A JP770987A JPH062896B2 JP H062896 B2 JPH062896 B2 JP H062896B2 JP 770987 A JP770987 A JP 770987A JP 770987 A JP770987 A JP 770987A JP H062896 B2 JPH062896 B2 JP H062896B2
- Authority
- JP
- Japan
- Prior art keywords
- rare earth
- molten steel
- denitrification
- earth metal
- ppm
- 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 - Fee Related
Links
- 229910052761 rare earth metal Inorganic materials 0.000 title claims description 35
- 150000002910 rare earth metals Chemical class 0.000 title claims description 34
- 229910000831 Steel Inorganic materials 0.000 title claims description 27
- 239000010959 steel Substances 0.000 title claims description 27
- 238000000034 method Methods 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 5
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 229910052760 oxygen Inorganic materials 0.000 claims description 5
- 239000001301 oxygen Substances 0.000 claims description 5
- 229910052717 sulfur Inorganic materials 0.000 claims description 5
- 239000011593 sulfur Substances 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 12
- 238000007792 addition Methods 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 6
- 238000007664 blowing Methods 0.000 description 5
- 230000007704 transition Effects 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910000976 Electrical steel Inorganic materials 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 150000002909 rare earth metal compounds Chemical class 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Description
【発明の詳細な説明】 〈発明の目的〉 産業上の利用分野 本発明は希土類金属による溶鋼の脱窒法に係り、詳しく
は、厚板製品の溶接部靱性改善に有効な希土類金属によ
る溶鋼の脱窒法に係る。DETAILED DESCRIPTION OF THE INVENTION Object of the Invention Industrial Field of the Invention The present invention relates to a denitrification method for molten steel with a rare earth metal, and more specifically, a denitrification of molten steel with a rare earth metal effective for improving the weld zone toughness of thick plate products. It is related to the Nitrogen Act
従来の技術 厚板製品では大入熱溶接時の溶接部靱性改善の点から、
製品中に含有するＮ量は低い方が好ましい。一般に、転
炉→２次精錬→連鋳あるいは造塊プロセスでは、溶銑段
階で窒素含有量（以下［Ｎ］で示す）は100ppm前後であ
り、転炉製錬中に10〜20ppm程度まで脱窒されるが、そ
の後の工程では何れも吸窒が進行し、半成品であるスラ
ブ中には40ppm程度の［Ｎ］が含有される。従来は、極
低窒化のニーズに対し、例えば、特開昭58-189315号の
如く転炉以降での吸窒を徹底的に防止する方法（すなわ
ち、未脱酸出鋼や注入時の雰囲気中のN2分圧を低下させ
る等）のみが実施されているにすぎない。このような吸
窒を防止する方法ではいかに徹底的に実施しても、第2
図に示すように鋳片中の［Ｎ］は20ppm程度が限界であ
る。これは各工程での完全な雰囲気制御が不可能なこと
および合金鉄中に含有される［Ｎ］によるためと考えら
れる。Conventional technology For thick plate products, from the viewpoint of improving the toughness of the weld during high heat input welding,
The lower the amount of N contained in the product, the better. Generally, in the converter → secondary refining → continuous casting or ingot making process, the nitrogen content (hereinafter referred to as [N]) is around 100 ppm at the hot metal stage, and denitrification is performed up to about 10 to 20 ppm during converter smelting. However, in the subsequent steps, nitrification progresses, and the semi-finished slab contains about 40 ppm [N]. Conventionally, in response to the need for extremely low nitriding, for example, as in JP-A-58-189315, a method of thoroughly preventing nitrogen absorption after the converter (that is, in an undeoxidized steel or in an atmosphere during injection) The N 2 partial pressure is reduced). No matter how thoroughly you implement such a method to prevent nitrogen absorption,
As shown in the figure, the limit of [N] in the cast slab is about 20 ppm. It is considered that this is because it is impossible to completely control the atmosphere in each step and [N] contained in the iron alloy.
また、希土類金属による脱窒効果は従来より知られてい
たが、溶鋼の事前処理を行なわずに希土類金属を添加し
ても、希土類金属は炭素や酸素等と優先的に反応するた
め、工業的なレベルでの脱窒は困難であった。Further, the denitrification effect of rare earth metals has been conventionally known, but even if rare earth metals are added without performing pretreatment of molten steel, the rare earth metals react preferentially with carbon, oxygen, etc. Denitrification at various levels was difficult.
発明が解決しようとする問題点 本発明はこれらの問題点の解決を目的とし、具体的に
は、溶鋼中の炭素含有量［Ｃ］および遊離酸素含有量
［Ｏ］freeを低下させることによって希土類金属による
脱窒を優先的に進行させる希土類金属による溶鋼の脱窒
法を提供することを目的とする。DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention aims to solve these problems, specifically, by reducing the carbon content [C] and the free oxygen content [O] free in the molten steel, the rare earth element is reduced. It is an object of the present invention to provide a denitrification method for molten steel by a rare earth metal that preferentially advances denitrification by a metal.
〈発明の構成〉 問題点を解決するための手段ならびにその作用 本発明は、炭素含有量0.01重量％以下、遊離酸素含有量
10ppm以下および硫黄含有量0.01重量％以下に溶製した
溶鋼中に希土類金属若しくは希土類金属含有物を希土類
金属純分として0.1〜3.0kg/tを添加し処理することを特
徴とする。<Structure of Invention> Means for Solving Problems and Its Action The present invention has a carbon content of 0.01% by weight or less and a free oxygen content.
The present invention is characterized in that a rare earth metal or a rare earth metal-containing material is added to 0.1 to 3.0 kg / t as a rare earth metal pure content in molten steel melted to 10 ppm or less and a sulfur content of 0.01% by weight or less and treated.
以下、図面によって本発明の手段たる構成ならびに作用
を説明すると、次の通りである。The structure and operation of the present invention will be described below with reference to the drawings.
第１図は実施例における転炉吹錬以降の各工程における
［Ｎ］の推移を示すグラフであり、第２図は従来法の転
炉吹錬以降の各工程における［Ｎ］の推移を示すグラフ
である。FIG. 1 is a graph showing the transition of [N] in each step after the converter blowing in the example, and FIG. 2 shows the transition of [N] in each step after the conventional blowing of the converter. It is a graph.
珪素鋼は従来より［Ｎ］ レベルが７〜10ppmと非常に
低いという特徴があった。珪素鋼においては、電磁特性
改善のため極低硫黄化が必要であるが、従来より特開昭
58-204115号記載の如く、希土類金属の添加により
［Ｓ］は40ppm→10ppmに低下することが知られていた。
この際に希土類金属の添加前後で［Ｎ］を分析したとこ
ろ、脱窒が進行していることが明らかとなった。これ
は、希土類金属添加時の溶鋼中［Ｃ］が50ppm以下、
［Ｏ］freeが10ppm以下となっているため、希土類金属
による脱窒が優先的に進行するためと考えられる。Silicon steel has a characteristic that the [N] level is as low as 7 to 10 ppm, which is much lower than the conventional one. Silicon steel requires extremely low sulfur to improve electromagnetic characteristics, but it has been hitherto known that it is difficult to reduce sulfur content.
As described in No. 58-204115, it has been known that the addition of rare earth metal reduces [S] from 40 ppm to 10 ppm.
At this time, analysis of [N] before and after the addition of the rare earth metal revealed that denitrification proceeded. This is because when the rare earth metal is added, [C] in molten steel is 50 ppm or less,
Since [O] free is 10 ppm or less, it is considered that denitrification by the rare earth metal preferentially proceeds.
希土類金属は溶鋼中の［Ｏ］，［Ｎ］，［Ｓ］および
［Ｃ］との親和力が強いことは従来より知られていた
が、一般の厚板製品のように［Ｃ］を0.04％以上に成分
調整された溶鋼に希土類金属を添加しても脱窒効果は認
められない。これは、希土類金属が炭化物生成等に消費
されるためである。これをCeを例として説明すると、Ce
の酸化物、窒化物、硫化物および炭化物の1600℃におけ
る生成自由エネルギーは、Ce2O3；−613000J/mol、Ce
S；−165000J/mol、CeN；−191000J/mol、CeC；−88000
J/molである。この中でCeCは他の化合物と比較して生成
しにくいと考えられるが、溶鋼中の［Ｏ］，［Ｓ］，
［Ｎ］が１×100〜１×101ppmであるのに対し、［Ｃ］
は１×102〜１×103ppmと2オーダー高いため、優先的に
炭化物を生成することによるものと考えられる。そこ
で、希土類金属を添加する前の事前溶鋼処理として真空
脱ガス装置により脱炭処理を施して溶鋼中の［Ｃ］を0.
01重量％以下とし、かつ溶鋼中［Ｏ］freeを10ppm以
下、［Ｓ］を0.01重量％以下とすることによって、希土
類金属と溶鋼中の［Ｎ］との反応を優先的に進行させる
溶鋼の脱窒法を開発するに至った。It has been known that rare earth metals have a strong affinity for [O], [N], [S] and [C] in molten steel, but 0.04% of [C] is used like general thick plate products. Even if a rare earth metal is added to the molten steel whose composition has been adjusted as described above, no denitrifying effect is observed. This is because the rare earth metal is consumed for carbide formation and the like. To explain this using Ce as an example, Ce
The free energy of formation of oxides, nitrides, sulfides and carbides of Ce at 1600 ° C is Ce 2 O 3 ; -613000J / mol, Ce
S; -165000J / mol, CeN; -191000J / mol, CeC; -88000
It is J / mol. Among these, CeC is considered to be less likely to be formed compared to other compounds, but [O], [S],
[N] is 1 × 10 0 to 1 × 10 1 ppm, while [C]
Is 2 orders of magnitude higher, 1 × 10 2 to 1 × 10 3 ppm, and is considered to be due to preferential formation of carbides. Therefore, as a preliminary molten steel treatment before adding the rare earth metal, decarburization treatment is performed by a vacuum degassing device to remove [C] in the molten steel.
By controlling the content of [O] free in the molten steel to 10 ppm or less and [S] to 0.01% by weight or less, the reaction between the rare earth metal and [N] in the molten steel is preferentially promoted. We have developed a denitrification method.
この際に［Ｃ］の上限を規制する理由は上述の通りであ
り、また、［Ｏ］freeの上限を規制する理由は［Ｃ］と
同様の理由である。すなわち、Ceを例とすれば1600℃に
おいて、Ce2O3およびCeNの生成自由エネルギーは、 Ce2O3(S)＝2Ce＋３０ ΔＧ０＝613000J/mol CeN(s)＝Ce+N ΔG0＝191000J/mol であり、これにより次の反応の自由エネルギーは、 Ce2O3+2N＝2CeN＋３０ ΔG0＝231000J/mol であり、この反応の平衡定数Kは3.63×10-7となる。従
って、Ceによる脱窒反応を効率的に進行させるには
［Ｏ］freeが低いほど好ましいが、工業的には10ppm以
下とすればよい。また、［Ｓ］についても脱窒効率上、
事前処理として0.01重量％以下とする必要がある。The reason for limiting the upper limit of [C] at this time is as described above, and the reason for limiting the upper limit of [O] free is the same as that for [C]. That is, taking Ce as an example, at 1600 ° C., the free energy of formation of Ce 2 O 3 and CeN is Ce 2 O 3 (S) = 2Ce + 30 ΔG 0 = 613000 J / mol CeN (s) = Ce + N ΔG 0 = It is 191000 J / mol, so that the free energy of the next reaction is Ce 2 O 3 + 2N = 2CeN + 30 ΔG 0 = 231000 J / mol, and the equilibrium constant K of this reaction is 3.63 × 10 −7 . Therefore, the lower [O] free is, the more preferable in order to efficiently proceed the denitrification reaction with Ce, but industrially, it may be 10 ppm or less. Also, for [S], in terms of denitrification efficiency,
As a pretreatment, the amount should be 0.01% by weight or less.
希土類金属(REM)添加時の溶鋼成分と脱窒率 の関係を求めた結果を第1表に示す。すなわち、処理前
の溶鋼中の［Ｃ］，［Ｏ］freeおよび［Ｓ］が本発明範
囲内にある実験No.４，５，７，８，９は希土類金属の
添加により脱窒率25〜56％が得られ、比較例のNo.１，
２，３，６の20％以下と比較して格段の脱窒率の向上が
見られた。Molten steel composition and denitrification rate when rare earth metal (REM) is added Table 1 shows the results of the relationship. That is, in Experiment Nos. 4, 5, 7, 8 and 9 in which [C], [O] free and [S] in the molten steel before the treatment are within the scope of the present invention, the denitrification rate is 25 to 25 due to the addition of the rare earth metal. 56% was obtained, which is No. 1 of the comparative example.
Compared with 20% or less of 2, 3 and 6, the denitrification rate was remarkably improved.
また、希土類金属の添加量については、上述の事前処理
による溶鋼成分により異なるが、0.1kg/t未満ではNo.10
に示すように工業的な脱窒は困難であり、また、3kg/t
以上添加してもNo.11に示すように脱窒率の向上がみら
れず、鋳造工程での希土類金属化合物によるノズル詰り
の発生頻度が大きくなるので有利ではない。Regarding the amount of rare earth metal added, it varies depending on the molten steel composition by the above-mentioned pretreatment, but if it is less than 0.1 kg / t, it is No. 10
Industrial denitrification is difficult, as shown in Fig.
Even with the above additions, the denitrification rate is not improved as shown in No. 11, and the nozzle clogging frequency due to the rare earth metal compound increases in the casting process, which is not advantageous.
実施例 以下、実施例によって更に説明する。 Examples Hereinafter, examples will be further described.
転炉吹錬後、未脱酸出鋼を実施し、RH脱ガス処理で脱炭
し、Al等による脱酸後、RH工程において希土類金属（La
30%、Ce50%、Pr5%、Nd14%）を1.0kg/t添加した際の各工程
での［Ｎ］の推移を第1図に示す。なお、希土類金属添
加前の溶鋼は上記事前処理によって本発明に係る
［Ｃ］，［Ｏ］free，［Ｓ］の範囲内にある。After blowing in the converter, undeoxidized steel is removed, decarburized by RH degassing, deoxidized with Al, etc., and rare earth metal (La
30%, Ce50%, Pr5%, Nd14%) 1.0 kg / t addition, the transition of [N] in each process is shown in FIG. The molten steel before adding the rare earth metal is within the range of [C], [O] free , and [S] according to the present invention by the above-mentioned pretreatment.
これを従来法に係る第2図と比較すると明らかなようにR
H前において約15ppmの［Ｎ］を含有する溶鋼は希土類金
属の添加により［Ｎ］が大幅に低下した。As can be seen by comparing this with Fig. 2 of the conventional method, R
In the molten steel containing about 15 ppm of [N] before H, the addition of the rare earth metal significantly reduced the [N].
すなわち、第2図に示した従来法では脱ガス処理中で2pp
mの［Ｎ］の上昇があるが、本発明法では7ppm前後の脱
窒が進行し、また、鋳造中におけるタンディッシュ内で
の［Ｎ］レベルは従来法より10ppm程度低下し約10ppm
［Ｎ］であった。従って、本発明法の適用により［Ｎ］
が10ppmレベルの極低窒素鋼の製造が可能となった。That is, in the conventional method shown in FIG.
Although there is an increase in [N] of m, denitrification of about 7 ppm proceeds in the method of the present invention, and the [N] level in the tundish during casting is reduced by about 10 ppm from the conventional method to about 10 ppm.
It was [N]. Therefore, by applying the method of the present invention, [N]
It became possible to manufacture ultra-low nitrogen steel with 10ppm level.
〈発明の効果〉 以上説明したように、本発明は、炭素含有量0.01重量％
以下、遊離酸素含有量10ppm以下および硫黄含有量0.01
重量％以下に溶製した溶鋼中に希土類金属若しくは希土
類金属含有物を希土類金属純分として0.1〜3.0kg/tを添
加し処理することを特徴とする希土類金属による溶鋼の
脱窒法であって、本法の適用により、［Ｎ］が10ppm前
後の極低窒素鋼の製造が可能となり、厚板製品における
大入熱溶接時の溶接部靱性が大幅に改善された。<Effect of the Invention> As described above, the present invention has a carbon content of 0.01% by weight.
Below, free oxygen content less than 10ppm and sulfur content 0.01
A denitrification method for molten steel by a rare earth metal, characterized by adding 0.1 to 3.0 kg / t as a rare earth metal pure content of a rare earth metal or a rare earth metal-containing material in molten steel melted to a weight percentage of By applying this method, it became possible to manufacture ultra-low nitrogen steel with [N] around 10 ppm, and the toughness of the welded part during large heat input welding in thick plate products was greatly improved.
第1図は実施例における転炉吹錬以降の各工程における
［Ｎ］の推移を示すグラフ、第2図は従来法の転炉吹錬
以降の各工程における［Ｎ］の推移を示すグラフであ
る。FIG. 1 is a graph showing the transition of [N] in each step after the converter blowing in the example, and FIG. 2 is a graph showing the transition of [N] in each step after the conventional blowing of the converter. is there.
Claims (1)
量10ppm以下および硫黄含有量0.01重量％以下に溶製し
た溶鋼中に希土類金属若しくは希土類金属含有物を希土
類金属純分として0.1〜3.0kg/tを添加し処理することを
特徴とする希土類金属による溶鋼の脱窒法。1. A rare earth metal or a rare earth metal-containing material in molten steel melted to a carbon content of 0.01% by weight or less, a free oxygen content of 10 ppm or less, and a sulfur content of 0.01% by weight or less as a rare earth metal pure content of 0.1 to 3.0. A denitrification method for molten steel with rare earth metals, characterized by adding and treating kg / t.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP770987A JPH062896B2 (en) | 1987-01-14 | 1987-01-14 | Denitrification of molten steel with rare earth metals |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP770987A JPH062896B2 (en) | 1987-01-14 | 1987-01-14 | Denitrification of molten steel with rare earth metals |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63176417A JPS63176417A (en) | 1988-07-20 |
| JPH062896B2 true JPH062896B2 (en) | 1994-01-12 |
Family
ID=11673267
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP770987A Expired - Fee Related JPH062896B2 (en) | 1987-01-14 | 1987-01-14 | Denitrification of molten steel with rare earth metals |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH062896B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2002313307B2 (en) | 2001-06-28 | 2005-08-11 | Nippon Steel Corporation | Low carbon steel sheet, low carbon steel cast piece and method for production thereof |
| JP5332568B2 (en) * | 2008-12-05 | 2013-11-06 | 新日鐵住金株式会社 | Denitrification method for molten steel |
| CN114590892B (en) * | 2020-12-04 | 2023-05-26 | 中国石油天然气集团有限公司 | Rare earth tail water denitrification device and method |
-
1987
- 1987-01-14 JP JP770987A patent/JPH062896B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63176417A (en) | 1988-07-20 |
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