JP2559692B2 - Anti-blurring defect prevention method for ultra low carbon cold rolled steel sheet - Google Patents
Anti-blurring defect prevention method for ultra low carbon cold rolled steel sheetInfo
- Publication number
- JP2559692B2 JP2559692B2 JP60116668A JP11666885A JP2559692B2 JP 2559692 B2 JP2559692 B2 JP 2559692B2 JP 60116668 A JP60116668 A JP 60116668A JP 11666885 A JP11666885 A JP 11666885A JP 2559692 B2 JP2559692 B2 JP 2559692B2
- Authority
- JP
- Japan
- Prior art keywords
- low carbon
- rolled steel
- steel sheet
- steel
- cold rolled
- 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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- Continuous Casting (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、極低炭素アルミキルド冷延鋼板の製造分野
に所属する技術であって、かかる冷延鋼板を焼鈍する際
に“フクレ欠陥”を生じさせないためのCaを使う新規に
知見した技術についての提案である。DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is a technique belonging to the field of manufacturing ultra-low carbon aluminum-killed cold-rolled steel sheets, in which "blister defects" are generated when such cold-rolled steel sheets are annealed. This is a proposal for a newly discovered technology that uses Ca to prevent generation.
（従来の技術） 最近、２次精錬技術の発達に伴い極低炭素アルミキル
ド鋼の連続鋳造が可能になってきた。それを可能にした
のは脱ガス技術の進歩であり、事実その結果として非金
属介在物（以下単に「介在物」という）の少ない清浄鋼
の製造が可能になった。しかし、それも主としてコスト
の面などで限界があった。(Prior Art) Recently, with the development of secondary refining technology, continuous casting of ultra-low carbon aluminum killed steel has become possible. This has been made possible by advances in degassing technology, and as a result, it has become possible to produce clean steel with few non-metallic inclusions (hereinafter simply referred to as "inclusions"). However, there was a limit mainly in terms of cost.
加えて従来は、介在物の大きさを炭素含有量との関連
で問題にするようなことはほとんどなく、以下にのべる
ような問題点を抱えていた。In addition, conventionally, the size of the inclusions has hardly been a problem in relation to the carbon content, and has the following problems.
（発明が解決しようとする問題点） 極低炭素冷延板を焼鈍すると、焼鈍済み鋼板の表面
に、幅１〜4mm長さ１〜6cmの隆起部分、いわゆる“フク
レ欠陥”が発生することが判った。このフクレ欠陥は、
鋼中の炭素含有量が0.015重量％以下のものにとりわけ
多く発生し、そのために製品歩留りの大巾な低下を招い
ていた。(Problems to be Solved by the Invention) When an extremely low carbon cold-rolled sheet is annealed, a bulged portion having a width of 1 to 4 mm and a length of 1 to 6 cm, a so-called "blister defect" may occur on the surface of the annealed steel sheet. understood. This blistering defect is
The carbon content in steel was 0.015% by weight or less, which was especially high, which resulted in a large decrease in product yield.
（問題点を解決するための手段） 極低炭素アルミキルド鋼製造時に起る上述の如き現象
に対し、本発明は、 Ｃ≦0.015重量％を含有するアルミキルド溶鋼中に、R
H脱ガス処理による溶製段階でCaまたはCa合金を添加す
ることにより、鋼中に２〜40重量ppmの金属Caを残留さ
せてCaO−Al2O3系介在物が生成するように処理し、しか
るのち連続鋳造に供するという方法、を採用して上述の
課題を解決するようにした。(Means for Solving the Problems) In contrast to the above-described phenomenon that occurs during the production of an ultra-low carbon aluminum killed steel, the present invention provides a method of adding R in an aluminum killed molten steel containing C ≦ 0.015% by weight.
By adding Ca or Ca alloy in the melting stage by H degassing, it is treated so that CaO-Al 2 O 3 -based inclusions are formed by leaving 2-40 ppm by weight of metallic Ca in the steel. The method described above was adopted to solve the above-mentioned problems.
つまり本発明は、鋼中に２〜40重量ppmの金属Caが残
留するように処理することによって、Al2O3介在物をCaO
−Al2O3系介在物に変化させ、その融点の低下を図るこ
とで、該Al2O3介在物を起因とする焼鈍時のフクレ欠陥
生成の防止を図るようにしたのである。That is, the present invention treats Al 2 O 3 inclusions with CaO by treating the steel so that 2-40 ppm by weight of metallic Ca remains.
By changing to —Al 2 O 3 type inclusions and lowering the melting point thereof, blistering defect formation during annealing due to the Al 2 O 3 inclusions is prevented.
（作用） 本発明者らの研究によると、Ｃ含有量が0.015重量％
以下のアルミキルド冷延鋼板の場合、これを焼鈍すると
多くの場合フクレ欠陥を生じさせることが判った。その
原因としては、色々考えられるが、鋼中の非金属介在物
とくにAl2O3の影響が最も大きい。(Function) According to the study by the present inventors, the C content is 0.015% by weight.
In the case of the following aluminum-killed cold-rolled steel sheets, it was found that annealing often causes blistering defects. There are various possible causes for this, but the most significant effect is non-metallic inclusions in the steel, especially Al 2 O 3 .
即ち、低炭素鋼になると地鉄（マトリックス）と介在
物との変形強さに著しく差があるために、冷間圧延を施
すと、硬いAl2O3に対して軟らかいマトリックスの部分
の方の伸びが大きくなり、その結果両者の境界部分にボ
イドを形造る。このボイドはAl2O3のサイズに比例して
おり、介在物が大きくなればなるほど大きくなる。とこ
ろで、こうしたボイドを有する冷延鋼板を焼鈍すると、
そのボイド中に雰囲気ガス（AVガス）中のH2が侵入する
が、冷却時特に急冷時にH2の溶解度が低下するので、結
局ボイド中のH2分圧が上昇し、Al2O3近傍の鋼板表面を
膨出させるというフクレ欠陥を生むのである。That is, since there is a marked difference in the deformation strength between the base iron (matrix) and the inclusions in low carbon steel, when cold rolling is performed, the soft matrix part is harder than the hard Al 2 O 3 part. The elongation increases, and as a result, a void is formed at the boundary between the two. This void is proportional to the size of Al 2 O 3 , and the larger the inclusion, the larger it becomes. By the way, when a cold rolled steel sheet having such voids is annealed,
H 2 in the atmosphere gas (AV gas) penetrates into the voids, but the solubility of H 2 decreases during cooling, especially during rapid cooling, so the partial pressure of H 2 in the voids eventually rises, and Al 2 O 3 near The blistering defect of bulging the steel plate surface is produced.
かかるフクレ欠陥は、上記ボイドが小さいとき、即ち
Al2O3介在物の大きさが小さいときには、上記内圧の上
昇が小さいために発生しないことが判った。そして、こ
のフクレ欠陥を生むAl2O3の鋼中へのトラップについて
研究したところ、その大部分はAl2O3を主成分としてい
る浸漬ノズルに凝集付着したAl2O3の一部が該ノズル表
面から離脱して運ばれてくるということがわかった。従
って、このフクレを防ぐにはAl2O3が浸漬ノズルに付着
しないようにすることが有効であるという結論を得た。Such blistering defects are caused when the void is small, that is,
It was found that when the size of the Al 2 O 3 inclusions is small, it does not occur because the increase in the internal pressure is small. Then, the blister produces defects was studied trap to Al 2 O 3 in the steel, the majority part of Al 2 O 3 aggregated adhered to the immersion nozzle are mainly composed of Al 2 O 3 is the It was found that they would be carried away from the nozzle surface. Therefore, it was concluded that it is effective to prevent Al 2 O 3 from adhering to the immersion nozzle in order to prevent this blistering.
そこで、本発明者らは、溶鋼中にCaまたはCa合金を添
加して残留Caを含む低炭素アルミキルド溶鋼について連
続鋳造を試みたところ、上記Al2O3介在物は低融点のCaO
−Al2O3系介在物となって、その融点低下分だけ浸漬ノ
ズルへのAl2O3の凝集付着が抑制できることを突きとめ
た。第２図は、金属態Caの含有量と浸漬ノズル詰り指数
との関係を示すものであるが、２重量ppm以上の残留Ca
量ではノズル詰り指数が著しく低下し、いわゆるCaO−A
l2O3系複合介在物の生成が予測された。従って、Ca≧2p
pm含有する溶鋼を上記浸漬ノズルを通じ連続鋳造して得
た低炭素アルミキルド冷延鋼板の場合には、ノズルへの
Al2O3凝集付着が無いのでフクレ欠陥が発生しづらいこ
とがわかる。このCaの含有量については、40重量ppm以
上含有させると、Caのもつ酸素親和力の故に鋼板表面に
錆（酸化）が生じやすくなり、清浄な鋼板表面を得るこ
とが難しくなるので、上限の設定が必要である。Therefore, when the present inventors tried continuous casting of a low carbon aluminum killed molten steel containing residual Ca by adding Ca or a Ca alloy to the molten steel, the Al 2 O 3 inclusions had a low melting point of CaO.
It was found that the Al 2 O 3 -based inclusions can suppress the agglomeration and adhesion of Al 2 O 3 to the immersion nozzle due to the decrease in the melting point. FIG. 2 shows the relationship between the content of metallic Ca and the clogging index of the immersion nozzle.
The nozzle clogging index significantly decreases with the amount of so-called CaO-A.
The formation of l 2 O 3 -based composite inclusions was predicted. Therefore, Ca ≧ 2p
In the case of a low carbon aluminum killed cold rolled steel sheet obtained by continuously casting molten steel containing pm through the above immersion nozzle,
It can be seen that blistering defects are less likely to occur because there is no Al 2 O 3 cohesive adhesion. Regarding the Ca content, if 40 wt ppm or more is included, rust (oxidation) easily occurs on the steel plate surface due to the oxygen affinity of Ca, and it becomes difficult to obtain a clean steel plate surface. is necessary.
なお、第２図中の浸漬ノズル詰り指数は、浸漬ノズル
の完全閉塞を5.0としたときのノズル詰りの程度を指標
化したものである。上述したCaもしくはCa合金の添加
は、塊状のままかワイヤ状にして脱ガス設備で行う。The immersion nozzle clogging index in FIG. 2 is an index of the degree of nozzle clogging when the complete clogging of the immersion nozzle is 5.0. The above-mentioned addition of Ca or Ca alloy is carried out in a degassing facility in the form of lump or wire.
なおCa無添加では、ノズル詰り指数は5.0となる。 When Ca is not added, the nozzle clogging index is 5.0.
（実施例） 本発明法に従って実施した結果を以下に説明する。Ca
−Al合金（Ca:35％、Al:65％）を、RH脱ガス設備内に投
入し、鋼中の金属態Caが5,10,15,25,35ppm残留するよう
に調整しこうして得られた冷延鋼板の各焼鈍コイルにつ
いて、フクレ発生率（フクレ欠陥の発生したコイル数の
割合）を調べた。その結果を第１図に示すが、無添加で
は2.5％あるフクレ欠陥の発生が、Ca含有量が２重量ppm
を超えるとフクレ欠陥の発生は顕著に低下している。こ
れはまた上記第２図に示した浸漬ノズル詰り指数の臨界
量とも一致しており、本発明の作用効果が確認できた。(Example) The results of the method according to the present invention will be described below. Ca
-Al alloy (Ca: 35%, Al: 65%) was put into the RH degassing equipment, and the metallic Ca in the steel was adjusted so that it remained at 5,10,15,25,35 ppm. For each annealed coil of the cold-rolled steel sheet, the blistering rate (ratio of the number of coils having blistering defects) was examined. The results are shown in Fig. 1. Without addition, 2.5% blistering defects were generated and the Ca content was 2 ppm by weight.
When it exceeds, the occurrence of blistering defects is significantly reduced. This is also in agreement with the critical amount of the immersion nozzle clogging index shown in FIG. 2, confirming the action and effect of the present invention.
（発明の効果） 以上説明したように本発明によれば、極低炭素アルミ
キルド冷延鋼板であっても、焼鈍時のフクレ欠陥を確実
に阻止ないしは減少させることができる。(Effect of the Invention) As described above, according to the present invention, it is possible to reliably prevent or reduce blistering defects during annealing even with an extremely low carbon aluminum killed cold rolled steel sheet.
第１図は、本発明実施例における鋼中Ca含有量とフクレ
欠陥発生率との関係を示すグラフ、 第２図は、鋼中Ca含有量と浸漬ノズル詰り指数との関係
を示すグラフである。FIG. 1 is a graph showing the relationship between the Ca content in steel and the blistering defect occurrence rate in Examples of the present invention, and FIG. 2 is a graph showing the relationship between the Ca content in steel and the immersion nozzle clogging index. .
Claims (1)
溶鋼中に、RH脱ガス処理による溶製段階でCaまたはCa合
金を添加することにより、鋼中に２〜40重量ppmの金属C
aを残留させてCaO−Al2O3系介在物が生成するように処
理し、しかるのち連続鋳造に供することを特徴とする極
低炭素冷延鋼板のフクレ欠陥防止方法。Claims: 1. By adding Ca or a Ca alloy in the melting stage by RH degassing to an aluminum-killed molten steel containing C ≤ 0.015% by weight, 2 to 40 ppm by weight of metal C in the steel is added.
A method for preventing blistering defects in an ultra-low carbon cold-rolled steel sheet, which is characterized in that a is retained to treat it so that CaO-Al 2 O 3 -based inclusions are formed, and then subjected to continuous casting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60116668A JP2559692B2 (en) | 1985-05-31 | 1985-05-31 | Anti-blurring defect prevention method for ultra low carbon cold rolled steel sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60116668A JP2559692B2 (en) | 1985-05-31 | 1985-05-31 | Anti-blurring defect prevention method for ultra low carbon cold rolled steel sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61276756A JPS61276756A (en) | 1986-12-06 |
| JP2559692B2 true JP2559692B2 (en) | 1996-12-04 |
Family
ID=14692932
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60116668A Expired - Lifetime JP2559692B2 (en) | 1985-05-31 | 1985-05-31 | Anti-blurring defect prevention method for ultra low carbon cold rolled steel sheet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2559692B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07100588A (en) * | 1993-09-30 | 1995-04-18 | Nippon Steel Corp | Production of cast double layer slab |
| JP3430672B2 (en) | 1994-10-18 | 2003-07-28 | Ｊｆｅスチール株式会社 | Melting method of ultra-low carbon aluminum killed steel |
| FR2792234B1 (en) * | 1999-04-15 | 2001-06-01 | Lorraine Laminage | TREATMENT TO IMPROVE THE CASABILITY OF CALM STEEL WITH CONTINUOUS CAST ALUMINUM |
| JP2001107178A (en) | 1999-10-06 | 2001-04-17 | Kawasaki Steel Corp | Ca-CONTAINING STEEL SMALL IN INCREASE IN RUST GENERATION |
| JP4214036B2 (en) | 2003-11-05 | 2009-01-28 | 新日本製鐵株式会社 | Thin steel plate excellent in surface properties, formability and workability, and method for producing the same |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6043034B2 (en) * | 1979-10-03 | 1985-09-26 | 株式会社東芝 | Manufacturing method of switching element |
-
1985
- 1985-05-31 JP JP60116668A patent/JP2559692B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61276756A (en) | 1986-12-06 |
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