JPH0555221B2 - - Google Patents
Info
- Publication number
- JPH0555221B2 JPH0555221B2 JP62233986A JP23398687A JPH0555221B2 JP H0555221 B2 JPH0555221 B2 JP H0555221B2 JP 62233986 A JP62233986 A JP 62233986A JP 23398687 A JP23398687 A JP 23398687A JP H0555221 B2 JPH0555221 B2 JP H0555221B2
- Authority
- JP
- Japan
- Prior art keywords
- powder
- mold
- mold powder
- ultra
- 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 - Fee Related
Links
- 239000000843 powder Substances 0.000 claims description 43
- 238000002425 crystallisation Methods 0.000 claims description 11
- 230000008025 crystallization Effects 0.000 claims description 11
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 10
- 238000009749 continuous casting Methods 0.000 claims description 9
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 229910052681 coesite Inorganic materials 0.000 claims description 2
- 229910052906 cristobalite Inorganic materials 0.000 claims description 2
- 238000002844 melting Methods 0.000 claims description 2
- 230000008018 melting Effects 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- 235000012239 silicon dioxide Nutrition 0.000 claims description 2
- 229910052682 stishovite Inorganic materials 0.000 claims description 2
- 229910052905 tridymite Inorganic materials 0.000 claims description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 8
- 239000010960 cold rolled steel Substances 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 238000005266 casting Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 229910004261 CaF 2 Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000004017 vitrification Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
- B22D11/11—Treating the molten metal
- B22D11/111—Treating the molten metal by using protecting powders
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
Description
〔産業上の利用分野〕
本発明は極低炭素鋼用連続鋳造モールドパウダ
ーに係り、特に冷間圧延鋼板のモールドパウダー
による表面欠陥を防止できるモールドパウダーに
関する。
〔従来の技術〕
従来、鋼の連続鋳造モールドパウダーは主成分
としてSiO2、CaO、Al2O3、Na2O、NaF、CaF2
等で構成されており、その鋳造スピードに応じて
粘性、軟化点を調整している。これらの内容は学
校法人鉄鋼短期大学人材開発センター発行の「連
続鋳造法」第92頁及び特開昭57−194205、特開昭
55−14865に開示されている。
しかしながら、Ｃ：0.0030％以下の極低炭素鋼
の連続鋳造に従来のモールドパウダーを使用しス
ラブ表面にパウダーが付着すると、極低炭素鋼の
硬度が柔らかいためロールにて表層下0.5〜1.5mm
まで押し付けられ、これがホツトスケールと共に
除去されず冷延鋼板の表面欠陥の原因となつてい
た。
〔発明が解決しようとする問題点〕
本発明の目的は上記従来技術の問題点を解決
し、表面付着パウダーによる冷延鋼板の表面欠陥
を防止できる極低炭素鋼用連続鋳造モールドパウ
ダーを提供するにある。
〔問題点を解決するための手段及び作用〕
本発明の要旨とするところは次の如くである。
すなわち、重量比にてSiO2：30〜60％、CaO：
20〜50％、Al2O3：１〜15％を基材として含む極
低炭素鋼用連続鋳造モールドパウダーにおいて、
Na2O：1.0未満、B2O3：５〜20％を含有し、溶
融パウダーが冷却するときの結晶化率を15％以下
にすることを特徴とする極低炭素鋼用連続鋳造モ
ールドパウダーである。
本発明者らはパウダーに起因する表面欠陥につ
いて種々検討した結果、その原因はモールド出側
でスラブ表面に付着したモールドパウダーがその
冷却過程で強固に結晶し、焼結した状態となり表
面から剥離せずに付着し鋳造ロールで押し付けら
れることに起因することを見い出した。そこで本
発明においては、モールド出側でスラブに付着し
たモールドパウダーを、冷却過程において結晶化
させずガラス化させることにより、パウダーが鋳
造ロールで鋳片に押し付けられた際、ガラス化さ
れているパウダーが破砕しスラブへの食い込みを
防止することを図つた。
まず、本発明における基材としてのSiO2、
CaO、Al2O3の作用と限定理由について説明す
る。
SiO：
SiO2は軟化点を下げる作用を有するが、30％
未満ではその効果が不十分であり、60％を越すと
逆に粘性が増加するので30〜60％の範囲に限定し
た。
CaO：
CaOが過剰になるとCaO／SiO2が増加し、パ
ウダーが結晶化するので好ましくない。従つて
CaO／SiO2の比を1.0以下になるようにSiO2含有
量によつて決め、20〜50％の範囲に限定した。
Al2O3：
パウダーはSiO2、CaO、Al2O3の主要３成分か
ら成るのでSiO2、CaOが上記により決定すれば、
おのずからAl2O3が決定されるので、１〜15％の
範囲に限定した。
次に本発明で重要な因子であるNa、Ｂについ
て説明する。第１表に３種のモールドパウダーの
成分及び性質を示した。Ａパウダーは従来から使
用されているものであり、ＢパウダーはB2O3を
添加したもの、ＣパウダーはNa2O量を減じB2O3
を添加したものである。
[Industrial Application Field] The present invention relates to continuous casting mold powder for ultra-low carbon steel, and particularly to mold powder that can prevent surface defects caused by mold powder on cold rolled steel sheets. [Prior art] Conventionally, continuous casting mold powder for steel has SiO 2 , CaO, Al 2 O 3 , Na 2 O, NaF, CaF 2 as main components.
The viscosity and softening point are adjusted according to the casting speed. These contents are from page 92 of "Continuous Casting Method" published by the Human Resources Development Center of the Junior College of Steel, and from JP-A-57-194205, JP-A-Sho.
No. 55-14865. However, if conventional molding powder is used for continuous casting of ultra-low carbon steel with C: 0.0030% or less, and the powder adheres to the slab surface, the hardness of ultra-low carbon steel is soft, so it is rolled 0.5 to 1.5 mm below the surface layer.
The hot scale was not removed along with the hot scale, causing surface defects on the cold rolled steel sheet. [Problems to be Solved by the Invention] An object of the present invention is to solve the problems of the above-mentioned prior art and to provide a continuous casting mold powder for ultra-low carbon steel that can prevent surface defects of cold-rolled steel sheets due to powder adhering to the surface. It is in. [Means and effects for solving the problems] The gist of the present invention is as follows.
That is, SiO2 : 30-60%, CaO:
Continuous casting mold powder for ultra-low carbon steel containing 20-50% and Al 2 O 3 : 1-15% as a base material,
Continuous casting mold powder for ultra-low carbon steel, containing less than 1.0 Na 2 O and 5 to 20% B 2 O 3 , and having a crystallization rate of 15% or less when the molten powder is cooled. It is. The inventors of the present invention have investigated various surface defects caused by powder, and have found that the cause of this is that the mold powder adhering to the slab surface on the exit side of the mold crystallizes strongly during the cooling process, becomes sintered, and cannot be peeled off from the surface. It was found that this was caused by the particles sticking together without being pressed and being pressed by the casting rolls. Therefore, in the present invention, by vitrifying the mold powder that adheres to the slab at the exit side of the mold without crystallizing it during the cooling process, when the powder is pressed against the slab by the casting roll, the powder is vitrified. The aim was to prevent the steel from breaking into the slab and cutting into the slab. First, SiO 2 as a base material in the present invention,
The effects and reasons for limitations of CaO and Al 2 O 3 will be explained. SiO: SiO 2 has the effect of lowering the softening point, but by 30%
If it is less than 60%, the effect will be insufficient, and if it exceeds 60%, the viscosity will increase, so it was limited to a range of 30 to 60%. CaO: Excess CaO increases CaO/SiO 2 and crystallizes the powder, which is not preferable. Accordingly
The CaO/SiO 2 ratio was determined to be 1.0 or less depending on the SiO 2 content, and was limited to a range of 20 to 50%. Al 2 O 3 : Powder consists of three main components: SiO 2 , CaO, and Al 2 O 3 , so if SiO 2 and CaO are determined as above,
Since Al 2 O 3 is determined naturally, it is limited to a range of 1 to 15%. Next, Na and B, which are important factors in the present invention, will be explained. Table 1 shows the components and properties of the three types of mold powders. Powder A is conventionally used, Powder B has B 2 O 3 added to it, and Powder C has B 2 O 3 with the amount of Na 2 O reduced.
is added.
【表】
これら等の３種のパウダーを1300℃の電気炉で
溶解後700〜900℃で取出し空冷の後、Ｘ線回析に
より各結晶の強度を測定することにより、次式に
より結晶化指数を求めた。
結晶化指数＝Ｉ／I0
ただし
Ｉ：空冷後のＸ線回析によるピーク強度
I0：Ａパウダーを1300℃で溶解後100℃／hrの冷
却速度で徐冷した時のＸ線回析によるピーク強
度
第１図に結晶化率（％）を示したがＡ、Ｂ、Ｃ
の順に低下しており、Na2Oを減じB2O3を添加し
たＣパウダーが最も結晶化し難くガラス化傾向の
大きいことが分かる。結晶化率は結晶化指数を％
で表わした数値である。
また、上記の３種のモールドパウダーの鉄板へ
の付着試験を行つた。すなわち、鉄板上で溶解
し、その後冷却して剥離するかどうか調査しその
結果を第２表に示したが、この結果も前記ガラス
化傾向と同様にNa2Oを減じB2O3を添加したＣパ
ウダーが最も成績がよく完全に剥離した。[Table] After melting these three types of powder in an electric furnace at 1300°C, take it out at 700-900°C, cool it in the air, and measure the strength of each crystal by X-ray diffraction. I asked for Crystallization index = I/I 0 However, I: Peak intensity by X-ray diffraction after air cooling I 0 : Based on X-ray diffraction when A powder was melted at 1300°C and then slowly cooled at a cooling rate of 100°C/hr Peak intensity The crystallization rate (%) is shown in Figure 1, A, B, C
It can be seen that the C powder with reduced Na 2 O and added B 2 O 3 is the least likely to crystallize and has a greater tendency to vitrify. Crystallization rate is the crystallization index as %
This is a numerical value expressed as . In addition, an adhesion test of the above three types of molding powders to an iron plate was conducted. That is, we investigated whether or not it melted on an iron plate and then cooled and peeled off, and the results are shown in Table 2. This result was also the same as the vitrification tendency described above, when Na 2 O was reduced and B 2 O 3 was added. The C powder that was applied had the best results and was completely peeled off.
従来例である前記Ａ、Ｂモールドパウダー及び
本発明実施例である前記Ｃモールドパウダーを使
用して実機において極低炭素鋼を鋳込み、スラブ
表面に付着したモールドパウダーの付着物の個数
を調査しその結果を第３表に示した。
Ultra-low carbon steel was cast in an actual machine using the mold powders A and B, which are conventional examples, and the mold powder C, which is an example of the present invention, and the number of deposits of mold powder adhering to the slab surface was investigated. The results are shown in Table 3.
【表】
第３表から本発明実施例のＣパウダーの場合は
モールドパウダーの付着個数は０であつた。
上記のＡおよびＣパウダーを使用したスラブの
一部を全面手入れを行い残部を無手入れにて熱間
圧延および冷間圧延を行い冷延鋼板のスリーバー
発生率を調査しその結果を第４表に示した。
第４表から本発明実施例のＣパウダー使用の場
合はスラブが無手入れでも冷延鋼板のスリーバー
発生率が低い。[Table] From Table 3, in the case of the C powder of the example of the present invention, the number of adhered mold powders was 0. A part of the slab using the above A and C powders was fully treated, and the remaining part was hot rolled and cold rolled without treatment, and the sliver occurrence rate of the cold rolled steel plate was investigated, and the results are shown in Table 4. Indicated. Table 4 shows that when using the C powder of the examples of the present invention, the incidence of slivers in cold rolled steel sheets is low even if the slab is not maintained.
本発明は上記実施例から明らかな如く、モール
ドパウダーのNa2Oを減じB2O3を増量し結晶化率
を下げることによつて、極低炭素鋼のモールドパ
ウダーに起因する表面欠陥を低減することができ
た。
As is clear from the above examples, the present invention reduces the surface defects caused by the mold powder of ultra-low carbon steel by reducing the Na 2 O and increasing the B 2 O 3 of the mold powder to lower the crystallization rate. We were able to.
第１図はモールドパウダーの取り出し温度と結
晶化率との関係を示す線図、第２図はモールドパ
ウダーの結晶化率とスラブ表面付着物個数との関
係を示す線図、第３図はモールドパウダーの
Na2O含有量と結晶化率との関係を示す線図、第
４図はモールドパウダーのB2O3含有量及びNa2O
含有量と粘性との関係を示す線図である。
Figure 1 is a diagram showing the relationship between mold powder removal temperature and crystallization rate, Figure 2 is a diagram showing the relationship between mold powder crystallization rate and the number of deposits on the slab surface, and Figure 3 is a diagram showing the relationship between mold powder removal temperature and crystallization rate. of powder
A diagram showing the relationship between Na 2 O content and crystallization rate, Figure 4 shows the B 2 O 3 content and Na 2 O content of mold powder.
It is a diagram showing the relationship between content and viscosity.
Claims (1)
％、Al2O3：１〜15％を基材として含む極低炭素
鋼用連続鋳造モールドパウダーにおいて、前記基
材成分のほかにNa2O：1.0％未満、B2O3：５〜
20％を含有し、かつ該モールドパウダーの溶融後
の取り出し温度900℃における結晶化率を15％以
下にすることを特徴とする極低炭素鋼用連続鋳造
モールドパウダー。1 SiO2 : 30-60%, CaO: 20-50 by weight
%, Al 2 O 3 : 1 to 15% as a base material, in a continuous casting mold powder for ultra-low carbon steel, in addition to the base material components, Na 2 O: less than 1.0%, B 2 O 3 : 5 to 5%.
Continuous casting mold powder for ultra-low carbon steel, characterized by containing 20% and having a crystallization rate of 15% or less at a temperature of 900° C. at which the mold powder is taken out after melting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23398687A JPS6475157A (en) | 1987-09-18 | 1987-09-18 | Continuous casting mold powder for extra-low carbon steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23398687A JPS6475157A (en) | 1987-09-18 | 1987-09-18 | Continuous casting mold powder for extra-low carbon steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6475157A JPS6475157A (en) | 1989-03-20 |
| JPH0555221B2 true JPH0555221B2 (en) | 1993-08-16 |
Family
ID=16963751
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23398687A Granted JPS6475157A (en) | 1987-09-18 | 1987-09-18 | Continuous casting mold powder for extra-low carbon steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6475157A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100430400B1 (en) * | 2001-05-25 | 2004-05-04 | 주식회사 서린건축사사무소 | Prefabricated Unit Way Of Underground Pipes |
| KR100530338B1 (en) * | 2001-12-26 | 2005-11-22 | 주식회사 포스코 | Mold Flux for manufacturing extremely low carbon cold rolled steel sheet |
| JP4265285B2 (en) * | 2003-05-29 | 2009-05-20 | Ｊｆｅスチール株式会社 | Mold powder for continuous casting of steel |
| KR101064987B1 (en) * | 2004-04-21 | 2011-09-15 | 주식회사 포스코 | Fluorine free mold flux for continuous casting of steel slab |
| KR101064988B1 (en) * | 2004-04-21 | 2011-09-15 | 주식회사 포스코 | Fluorine free boron oxide system mold flux for continuous casting of steel slab |
| JP4513737B2 (en) * | 2005-12-19 | 2010-07-28 | 住友金属工業株式会社 | Mold flux for continuous casting of steel |
| KR100749025B1 (en) * | 2006-06-22 | 2007-08-13 | 주식회사 포스코 | Mold flux and continuous casting method using the same |
| JP5037612B2 (en) * | 2006-06-22 | 2012-10-03 | ポスコ | Mold flux and continuous casting method using the same |
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| CN109967706B (en) * | 2019-05-05 | 2021-02-26 | 西峡县西保冶金材料有限公司 | Function protection material of continuous casting crystallizer for ultra-low carbon IF steel |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5167227A (en) * | 1974-12-07 | 1976-06-10 | Sakai Chemical Industry Co | CHUZOYO FURATSUKUSU |
| JPS6114055A (en) * | 1984-06-28 | 1986-01-22 | Nippon Steel Corp | Molten metal surface protective material for continuous casting of steel having less surface defect and internal defect |
-
1987
- 1987-09-18 JP JP23398687A patent/JPS6475157A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5167227A (en) * | 1974-12-07 | 1976-06-10 | Sakai Chemical Industry Co | CHUZOYO FURATSUKUSU |
| JPS6114055A (en) * | 1984-06-28 | 1986-01-22 | Nippon Steel Corp | Molten metal surface protective material for continuous casting of steel having less surface defect and internal defect |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6475157A (en) | 1989-03-20 |
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| LAPS | Cancellation because of no payment of annual fees |