JPH0356824B2 - - Google Patents
Info
- Publication number
- JPH0356824B2 JPH0356824B2 JP60000414A JP41485A JPH0356824B2 JP H0356824 B2 JPH0356824 B2 JP H0356824B2 JP 60000414 A JP60000414 A JP 60000414A JP 41485 A JP41485 A JP 41485A JP H0356824 B2 JPH0356824 B2 JP H0356824B2
- Authority
- JP
- Japan
- Prior art keywords
- mold
- slab
- vibration
- waveform
- speed
- 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
Links
- 238000000034 method Methods 0.000 claims description 17
- 230000007935 neutral effect Effects 0.000 claims description 2
- 238000009749 continuous casting Methods 0.000 description 12
- 238000005266 casting Methods 0.000 description 11
- 230000010355 oscillation Effects 0.000 description 11
- 210000000078 claw Anatomy 0.000 description 9
- 229910001220 stainless steel Inorganic materials 0.000 description 9
- 229910000975 Carbon steel Inorganic materials 0.000 description 8
- 239000010962 carbon steel Substances 0.000 description 8
- 239000000843 powder Substances 0.000 description 8
- 239000010935 stainless steel Substances 0.000 description 8
- 239000011651 chromium Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 229910052804 chromium Inorganic materials 0.000 description 5
- 238000005204 segregation Methods 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004904 shortening Methods 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 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
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
- B22D11/053—Means for oscillating the moulds
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
Description
〔産業上の利用分野〕
この発明は、炭素含有量が0.08〜0.16wt.％の炭
素鋼またはクロム含有量が17wt.％のステンレス
鋼（SUS 430）を連続鋳造するに当たり、鋳片
に横割れ等の表面疵や、鋳型内におけるシエルの
破断に基づくブレークアウト等が発生せず、しか
も、鋳造速度を落とすことなく高能率で鋳造する
ことができる、連続鋳造鋳片の表面性状改善方法
に関するものである。
〔従来の技術〕
竪型連続鋳造機による鋼の連続鋳造は、タンデ
イツシユ内に収容されている溶鋼を、水冷式竪型
鋳型内に供給し、鋳型内で凝固シエルを形成さ
せ、このようにして周囲にシエルが形成された未
凝固鋳片を、鋳型から連続的に引抜くことによつ
て行われている。鋳型内で健全なシエルを形成さ
せるために、通常、鋳型を一定ピツチで上下方向
に振動させ、且つ、鋳型内の溶鋼の表面上にパウ
ダーを添加している。
上述した鋳型の振動は、従来、第３図に示すよ
うな正弦波形によつて行われていた。第４図は、
従来の正弦波形の際の鋳型の振動速度（Vm）を
示すグラフであつて、Vcは鋳片の引抜速度を、
Vm−Vcは鋳型の振動速度（上昇時の最大速度）
と鋳片の引抜速度との相対速度差を示す。この相
対速度差は、鋳型と鋳片のシエルとの間に摩擦抵
抗が存在する場合、鋳型がシエルに及ぼす引張り
応力の最大値を意味する。
〔発明が解決しようとする課題〕
炭素含有量が0.08〜0.16wt.％の炭素鋼を連続鋳
造するに当り、その凝固過程における1490℃付近
の温度の鋳片に、Ｌ＋δ→γ（但し、Ｌ：溶融金
属、δ：フエライト、γ：オーステナイト）の包
晶反応が認められる。
上述の反応時に、鋳片が収縮して急激にその体
積が変化するので、第１０図に示すように凝固シ
エルの形状が不均一になり、鋳型１とシエル２と
の間に空〓３が生ずる。このような空〓３が生じ
た部分におけるシエル２の抜熱は小となるので、
凝固が遅れる。従つて、鋳型１内におけるシエル
２の厚さが不均一となる結果、鋳型１とシエル２
との間で発生する摩擦抵抗により、シエル２の薄
い部分において、オツシレーシヨンマークの谷部
に爪が生じ、オツシレーシヨンマークの起点とす
る割れが発生しやすくなる。第１１図に、上記の
ようにして鋳片４に生じた割れの形状を示す。同
図において、５は鋳片４のコーナー部に生ずるか
ぎ状の割れ、６は鋳片４のコーナー部にその厚さ
方向に生ずる割れ、７は鋳片のコーナー部にその
幅方向に生ずる割れである。
上述のように包晶反応によつて鋳片４に生ずる
割れについて、次のようなことが知られている。
(1) 割れの発生と、２次冷却の条件即ち冷却の強
弱とは関係がない。
(2) 鋳型１の短辺は、第１２図に示すようにその
上端から下端に向けて内側に傾斜しているが、
このテーパＴの寸法を小にすると、短辺の内面
と、短辺側のシエルとの摩擦抵抗が減少する結
果、割れが低減する。
(3) 鋳片に発生した割れの中には、鋳型内の溶鋼
の表面上に添加されたパウダーが詰つているこ
とが認められるから、上記割れは鋳型１内で発
生する。
このようなことから、上記鋳片の割れを防止す
るためには、鋳片の引抜きを0.9ｍ／分以下の低
速で行なう方法しかなく、生産能率の低下が避け
られない問題があつた。
またクロム含有量が17wt.％以下のステンレス
鋼（SUS 430）の場合には、高温強度および絞
り値が他のオーステナイト系ステンレス鋼に比
べ、融点近傍において低いため、鋳型とシエルと
の間の摩擦抵抗によりシエルが破断して、ブレー
クアウトが発生しやすい。第１３図は、SUS
430（融点1425〜1510℃）の引張り強さと絞り値を
示すグラフである。
上述のようなステンレス鋼（SUS 430）のシ
エル破断を防止するためには、鋳片の引抜きを
0.8ｍ／分以下の低速で行ない、極力シエルの厚
さを確保しつつ鋳造することが必要で、このため
生産能率の低下が避けられない問題があつた。
また、ステンレス鋼鋳片は、Cr、Ni等の酸化
されにくい元素を含むので、酸化スケールの厚さ
が非常に薄いため、鋳型の振動によつて鋳片の表
面に生ずるオツシレーシヨンマークが深い。更
に、オツシレーシヨンマークの谷部に、Ni、Ｐ、
Mn等の元素が富化して偏析が生じ、製品表面に
光沢むらが発生しやすい問題があつた。
特開昭58−3755号公報、特開昭58−38646号公
報等には、中炭域鋼スラブを、正弦波形により鋳
型を振動させながら連続鋳造するに際し、ネガテ
イブストリツプ時間を短くすることによつて、鋳
片の割れを軽減する方法が開示されている。
しかしながら、正弦波形により鋳型を振動させ
ながら連続鋳造するに際し、ネガテイブストリツ
プ時間を短くするためには、鋳型の振動数または
振幅を著しく小にしなければならない。このよう
な振動条件によつて鋳造を行うと、鋳片のシエル
に圧縮力が加わらなくなり、シエルの切断等が生
じて、鋳片を安定して引抜くことができなくな
る。
従つて、この発明の目的は、炭素含有量が0.08
〜0.16wt.％の炭素鋼またはクロム含有量が17wt.
％のステンレス鋼（SUS 430）を連続鋳造する
に当たり、鋳片の表層に爪が発生せず、鋳片のコ
ーナー部付近に包晶反応による割れ、および、鋳
型とシエルとの間の摩擦抵抗によるシエルの破断
が生ぜす、連続鋳造鋳片の表面性状を改善するこ
とができ、しかも、鋳造速度を落とすことなく高
速度で且つ安定して連続鋳造することができる方
法を提供することにある。
〔課題を解決するための手段〕
この発明は、鋳型を上下方向に一定のピツチで
振動させながら、前記鋳型から鋳片を所定速度で
引抜くことにより連続鋳造鋳片を製造するに当た
り、
前記鋳型をゆつくりと上昇させた後、急速に下
降させることによる、下記式
α＝Ｂ／Ａ×100（％）
但し、
α：振動波形の歪率
Ａ：正弦波形の、鋳型上死点から中立点までの時
間（sec）
Ｂ：非正弦波形の鋳型上死点の、正弦波形のとき
の鋳型上死点からのずれを示す時間（sec）
によつて表わされる振動波形の歪率（α）が20％
以上の非正弦波形によつて、前記鋳型を振動させ
て、前記鋳型の振動速度が前記鋳片の引き抜き速
度よりも早いネガテイブストリツプ時間を短くな
し、かくして、前記鋳片の表面性状を改善し、前
記鋳片に生ずる横割れおよびブレークアウトを低
減せしめることに特徴を有するものである。
次に、この発明を、図面を参照しながら説明す
る。
第１図は、この発明の方法の一実施態様を示す
鋳型の振動波形のグラフ、第２図は、同じく鋳型
の振動速度を示すグラフである。
この発明の方法においては、鋳型を、第１図に
示すような非正弦波形となるように一定ピツチで
上下方向に振動させる。即ち第２図に示すよう
に、鋳型をゆつくりと上昇させた後、急速に下降
させる非正弦波形で振動させ、鋳型の振動速度
（Vm）が鋳片の引抜速度（Vc）より速い時間即
ちネガテイブストリツプ時間を、第４図に示す従
来の正弦波形の場合に比べて短くする。
この結果、鋳型の振動速度と鋳片の引抜速度と
の相対速度差（Vm−Vc）は小さくなり、鋳型
とシエルとの間の摩擦抵抗を減少させることがで
きる。
第５図は、鋳型の振動波形の歪率と摩擦力指数
との関係を示すグラフである。第５図において振
動波形の歪率（α）は、同図中に示した正弦波形
に対する非正弦波形の偏倚量Ｂ／Ａ×100（％）
（但し、Ａ：正弦波形の、鋳型上死点から中立点
までの時間（sec）、Ｂ：非正弦波形の鋳型上死点
の、正弦波形のときの鋳型上死点からのずれを示
す時間（sec））を示す。
また摩擦力指数は、（Vm−Vc）／Ｑを示す。
ここで、Ｑはスラブ１m2当りのパウダーの流れ込
み量（Kg／m2）であつて、このパウダー流れ込み
量は、ポジテイブストリツプ時間（鋳型の振動速
度が鋳片の引抜速度よりも遅い時間）に比例する
ｑ＝atpの関係から求めた。上式において、ｑは
パウダー流れ込み量（スラブ１cm当り、１サイク
ルに流れ込むパウダーの重量ｇ／サイクル・cm）、
tpはポジテイブストリツプ時間（sec）、ａはパウ
ダーの溶融特性、鋳型の振動条件および鋳片引抜
速度によつて定まる係数である。
第５図は、鋳型の振動ストロークが８mm、振動
数が120cpm、鋳片引抜速度が1.0ｍ／minの場合
の例であつて、同図から明らかなように、振動波
形の歪率が０％（正弦波形）の場合に比べ、振動
波形の歪率が大になるに従つて摩擦力指数は減少
し、上記歪率が20％になると、０％の場合に比べ
て摩擦力指数が30.8％（18.5−12.8／18.5×100）減少
し、上記歪率が40％になると、０％の場合に比べ
て摩擦力指数が48.6％（18.5−9.5／18.5×100）減少す
る。
このような摩擦力指数の減少の70〜80％は、鋳
型の振動速度と鋳片の引抜速度との相対速度差
（Vm−Vc）が小さくなつたことによるものであ
り、その20〜30％は、鋳型の振動波形を非正弦波
形としたことによりポジテイブストリツプ時間
（tp）が増加し、パウダーの流れ込み量が増大し
て、鋳型とシエルとの間の潤滑が改善され、更
に、ネガテイブストリツプ時間が短いために、オ
ツシレーシヨンマークが浅く、且つ、オツシレー
シヨンマークの谷部に生ずる偏析が軽減したから
である。
上述した点から、この発明においては、鋳型
を、α＝Ｂ／Ａ×100（％）によつて表わされる振
動波形の歪率（α）が20％以上の非正弦波形によ
つて、且つ、鋳型の振動速度が鋳片の引き抜き速
度よりも早いネガテイブストリツプ時間を短くし
て振動させるのである。
次に、この発明を実施例により説明する。
実施例 １
鋳型を、振動ストローク８mm、振動数100cpm
の条件によつて、以下に示す本発明方法および従
来方法により、上下方向に振動させながら、炭素
含有量0.08〜0.16wt.％の炭素鋼を連続鋳造し、厚
さ250mm、幅1000mmの鋳片を製造した。
なお、振動条件を下記に示す。
(1) 振動発生装置：
電気−油圧サーボ方式
振動１周期を100分割し、制御している。
(2) 非正弦波形の作り方：
片振幅：１mmのときに、下記Ａ式の定数を下
表のように定めることにより、非正弦波形の原
形を得る。
任意の波形歪率の非正弦波形に対しては、下
表に示す６つの波形の線形結合により非正弦波
形を得ている。
Ｚ＝5
〓i=1
aisin（2πnt）
[Industrial Application Field] This invention is aimed at preventing transverse cracks in slabs during continuous casting of carbon steel with a carbon content of 0.08 to 0.16 wt.% or stainless steel (SUS 430) with a chromium content of 17 wt.%. This invention relates to a method for improving the surface properties of continuously cast slabs, which does not cause surface defects such as the above or breakouts due to breakage of the shell in the mold, and can be cast with high efficiency without reducing the casting speed. It is. [Prior Art] Continuous casting of steel using a vertical continuous casting machine involves supplying molten steel contained in a tundish into a water-cooled vertical mold, forming a solidified shell in the mold, and in this way This is done by continuously pulling out an unsolidified slab with a shell around it from a mold. In order to form a healthy shell within the mold, the mold is usually vibrated vertically at a constant pitch and powder is added onto the surface of the molten steel within the mold. Conventionally, the mold vibration described above has been performed using a sinusoidal waveform as shown in FIG. Figure 4 shows
This is a graph showing the vibration speed (Vm) of the mold in the case of a conventional sine waveform, where Vc is the drawing speed of the slab,
Vm−Vc is the vibration speed of the mold (maximum speed when rising)
It shows the relative speed difference between the drawing speed of the slab and the drawing speed of the slab. This relative velocity difference means the maximum value of the tensile stress that the mold exerts on the shell when there is frictional resistance between the mold and the shell of the slab. [Problem to be solved by the invention] When continuously casting carbon steel with a carbon content of 0.08 to 0.16 wt.%, L+δ→γ (however, L : molten metal, δ: ferrite, γ: austenite) peritectic reaction is observed. During the above-mentioned reaction, the slab shrinks and its volume changes rapidly, so that the shape of the solidified shell becomes uneven as shown in Figure 10, and a void 3 is created between the mold 1 and the shell 2. arise. Since the heat removal from the shell 2 in the area where such a void 3 has occurred is small,
Coagulation is delayed. Therefore, the thickness of the shell 2 in the mold 1 becomes non-uniform, and as a result, the thickness of the mold 1 and the shell 2 become uneven.
Due to the frictional resistance generated between the shell 2 and the thin portion of the shell 2, claws are formed in the valleys of the oscillation marks, and cracks are likely to occur at the starting points of the oscillation marks. FIG. 11 shows the shape of the crack that occurred in the slab 4 as described above. In the figure, 5 is a hook-shaped crack that occurs at the corner of the slab 4, 6 is a crack that occurs at the corner of the slab 4 in the thickness direction, and 7 is a crack that occurs at the corner of the slab in the width direction. It is. The following is known about the cracks that occur in the slab 4 due to the peritectic reaction as described above. (1) There is no relationship between the occurrence of cracks and the conditions of secondary cooling, that is, the strength of cooling. (2) The short sides of the mold 1 are inclined inward from the upper end to the lower end as shown in Fig. 12.
When the dimension of this taper T is made small, the frictional resistance between the inner surface of the short side and the shell on the short side is reduced, and as a result, cracks are reduced. (3) The cracks generated in the slab are found to be filled with powder added to the surface of the molten steel in the mold, so the cracks occur in the mold 1. For this reason, the only way to prevent cracking of the slab is to draw the slab at a low speed of 0.9 m/min or less, which inevitably leads to a decrease in production efficiency. In addition, in the case of stainless steel (SUS 430) with a chromium content of 17 wt.% or less, the high temperature strength and reduction of area are lower near the melting point than other austenitic stainless steels, so the friction between the mold and the shell is low. Resistance tends to cause the shell to rupture, resulting in a breakout. Figure 13 shows SUS
430 (melting point: 1425-1510°C) is a graph showing the tensile strength and reduction of area. In order to prevent the shell breakage of stainless steel (SUS 430) as mentioned above, it is necessary to pull out the slab.
It was necessary to perform casting at a low speed of 0.8 m/min or less and to ensure the thickness of the shell as much as possible, which posed the problem of an unavoidable drop in production efficiency. In addition, since stainless steel slabs contain elements that are difficult to oxidize, such as Cr and Ni, the thickness of the oxide scale is very thin, so the oscillation marks that occur on the slab surface due to mold vibrations are deep. . Furthermore, Ni, P,
There was a problem in that elements such as Mn were enriched and segregation occurred, resulting in uneven gloss on the product surface. JP-A No. 58-3755, JP-A No. 58-38646, etc. disclose methods for shortening the negative stripping time when continuously casting medium-coal range steel slabs while vibrating the mold with a sinusoidal waveform. discloses a method for reducing cracking of slabs. However, when performing continuous casting while vibrating the mold with a sinusoidal waveform, the frequency or amplitude of vibration of the mold must be significantly reduced in order to shorten the negative stripping time. If casting is performed under such vibration conditions, no compressive force will be applied to the shell of the slab, and the shell will break, etc., making it impossible to pull out the slab stably. Therefore, the object of this invention is to reduce the carbon content to 0.08
Carbon steel with ~0.16wt.% or chromium content of 17wt.
When continuously casting % stainless steel (SUS 430), there were no claws on the surface of the slab, cracks near the corners of the slab due to peritectic reaction, and frictional resistance between the mold and shell. It is an object of the present invention to provide a method that can improve the surface properties of continuously cast slabs caused by shell breakage, and can perform continuous casting at high speed and stably without reducing the casting speed. [Means for Solving the Problems] The present invention provides continuous casting slabs for manufacturing continuous casting slabs by pulling slabs from the mold at a predetermined speed while vibrating the mold vertically at a constant pitch. The equation below is α = B / A × 100 (%) by slowly raising and then rapidly lowering the B: The time (sec) indicating the deviation of the top dead center of the mold with a non-sinusoidal waveform from the top dead center of the mold with a sine waveform. 20%
The above non-sinusoidal waveform vibrates the mold to shorten the negative stripping time in which the vibration speed of the mold is faster than the drawing speed of the slab, thus improving the surface properties of the slab. The present invention is characterized in that horizontal cracks and breakouts occurring in the slab are reduced. Next, the present invention will be explained with reference to the drawings. FIG. 1 is a graph of the vibration waveform of a mold showing an embodiment of the method of the present invention, and FIG. 2 is a graph showing the vibration speed of the mold. In the method of this invention, the mold is vibrated vertically at a constant pitch so as to form a non-sinusoidal waveform as shown in FIG. That is, as shown in Fig. 2, the mold is vibrated with a non-sinusoidal waveform that slowly rises and then rapidly descends, and the vibration speed (Vm) of the mold is faster than the drawing speed (Vc) of the slab, i.e. The negative strip time is made shorter than in the case of the conventional sine waveform shown in FIG. As a result, the relative speed difference (Vm-Vc) between the vibration speed of the mold and the drawing speed of the slab becomes small, and the frictional resistance between the mold and the shell can be reduced. FIG. 5 is a graph showing the relationship between the distortion rate of the vibration waveform of the mold and the frictional force index. In Figure 5, the distortion rate (α) of the vibration waveform is the deviation amount B/A of the non-sinusoidal waveform with respect to the sine waveform shown in the figure x 100 (%).
(However, A: Time from the top dead center of the mold to the neutral point (sec) for a sine waveform, B: Time indicating the deviation of the top dead center of the mold for a non-sinusoidal waveform from the top dead center of the mold for a sine waveform. (sec)). Moreover, the frictional force index shows (Vm-Vc)/Q.
Here, Q is the amount of powder flowing in per 1 m 2 of slab (Kg/m 2 ), and this amount of powder flowing in is the period during which the vibration speed of the mold is slower than the drawing speed of the slab. ) was determined from the relationship q=atp, which is proportional to In the above formula, q is the amount of powder flowing in (weight of powder flowing in 1 cycle per 1 cm slab, g/cycle cm),
tp is the positive strip time (sec), and a is a coefficient determined by the melting characteristics of the powder, the vibration conditions of the mold, and the slab drawing speed. Figure 5 shows an example in which the vibration stroke of the mold is 8 mm, the vibration frequency is 120 cpm, and the slab drawing speed is 1.0 m/min. As is clear from the figure, the distortion rate of the vibration waveform is 0%. (compared to the case of a sine waveform), as the distortion rate of the vibration waveform increases, the friction force index decreases, and when the above distortion rate becomes 20%, the friction force index decreases by 30.8% compared to the case of 0%. (18.5-12.8/18.5×100) and when the above strain rate becomes 40%, the frictional force index decreases by 48.6% (18.5-9.5/18.5×100) compared to the case of 0%. 70 to 80% of this decrease in the frictional force index is due to the decrease in the relative speed difference (Vm - Vc) between the vibration speed of the mold and the drawing speed of the slab; By making the vibration waveform of the mold a non-sinusoidal waveform, the positive strip time (tp) increases, the amount of powder flowing in increases, and the lubrication between the mold and shell is improved. This is because the stripping time is short, so the oscillation marks are shallow, and the segregation that occurs in the valleys of the oscillation marks is reduced. From the above points, in this invention, the mold is formed by a non-sinusoidal waveform in which the distortion rate (α) of the vibration waveform represented by α=B/A×100 (%) is 20% or more, and The vibration is made by shortening the negative strip time, in which the vibration speed of the mold is faster than the withdrawal speed of the slab. Next, the present invention will be explained using examples. Example 1 The mold was set at a vibration stroke of 8 mm and a vibration frequency of 100 cpm.
Under the following conditions, carbon steel with a carbon content of 0.08 to 0.16 wt.% was continuously cast by the method of the present invention and the conventional method shown below while vibrating in the vertical direction, and a slab with a thickness of 250 mm and a width of 1000 mm was obtained. was manufactured. The vibration conditions are shown below. (1) Vibration generator: Electric-hydraulic servo system One vibration period is divided into 100 parts for control. (2) How to create a non-sinusoidal waveform: When half amplitude is 1 mm, obtain the original form of the non-sinusoidal waveform by determining the constants of formula A below as shown in the table below. For non-sinusoidal waveforms with arbitrary waveform distortion factors, the non-sinusoidal waveforms are obtained by linear combination of the six waveforms shown in the table below. Z= 5 〓 i=1 a i sin(2πnt)
【表】
第６図Ａは、上記鋳造を下記に示す本発明方法
で行なつた場合と従来法で行なつた場合の、鋳片
に生じた横割れ発生指数（横割れ個数÷単位面積
（m2））を示すグラフである。
本発明方法
鋳片引抜速度（Vc）：1.0ｍ／分
鋳型の形状：弱テーパ
鋳型の振動波形：非正弦波（α＝40％）
ネガテイブストリツプ時間：0.173秒
従来例 １
鋳型引抜速度（Vc）：1.0ｍ／分
鋳型の形状：強テーパ
鋳型の振動波形：正弦波
ネガテイブストリツプ時間：0.222秒
従来例 ２
鋳片引抜速度（Vc）：0.8ｍ／分
鋳型の形状：強テーパ
鋳型の振動波形：正弦波
ネガテイブストリツプ時間：0.238秒
従来例 ３
鋳片引抜速度（Vc）：0.8ｍ／分
鋳型の形状：弱テーパ
鋳型の振動波形：正弦波
ネガテイブストリツプ時間：0.238秒
上記において、強テーパとは、第１２図に示す
鋳型１の上端から下端に向けてのテーパＴ
（Ａ−Ｂ／Ａ×100１／Ｌ）％が、0.8％／ｍの場合であ
り、弱テーパとは上記Ｔが0.65％／ｍの場合であ
る。
第６図Ａから明らかなように、本発明方法の場
合は、鋳片の引抜速度を1.0ｍ／分の高速として
も、鋳片の横割れ発生指数は極めて低く、従来例
３の鋳片引抜速度を0.8ｍ／分とし且つ弱テーパ
の形状の鋳型を使用した場合とほぼ同じとなつ
て、従来例３に比べ生産能率を約20％向上させる
ことができた。
第６図Ｂは、波形の歪率（α）を０〜50％の範
囲内で変えて連続鋳造した場合の、鋳片に生じた
横割れ発生指数を示すグラフである。第６図Ｂか
ら明らかなように、歪率（α）を20％以上にする
と、横割れ発生指数は顕著に減少した。
第７図は、鋳型の振動波形の歪率の鋳片のオツ
シレーシヨンマークの谷部に生ずる爪の発生頻度
との関係を示すグラフである。一般に炭素鋼の鋳
片に生ずるオツシレーシヨンマークには、第８図
ａに示すようなオツシレーシヨンマークの谷部に
爪が生じて偏析線を伴つている場合と、同図ｂに
示すようなオツシレーシヨンマークの谷部に爪が
生じない偏析線のない場合とがある。このような
爪は、彎曲型連続鋳造機によつて鋳片を鋳造する
場合の鋳片矯正時に、鋳片の上面側において引張
り応力を受け、爪または谷に沿つて横割れが生ず
る原因となる。
第７図から明らかなように、上述した爪の発生
頻度は、鋳型の振動波形の歪率が０％（正弦波
形）の場合は45〜50％であるが、上記歪率が20％
の非正弦波形の場合は約35％に、上記歪率が40％
の非正弦波形の場合は約20％になり、爪によつて
生ずる鋳片の横割れを大幅に減少させることがで
きた。
実施例 ２
次に、鋳型を、振動ストローク８mm、振動数
100cpmの条件によつて上下方向に振動させなが
ら、Cr含有量が17wt.％のステンレス鋼（SUS
430）を連続鋳造し、厚さ250mm、幅1500mmの鋳片
を鋳造した。第９図は、上記鋳造を下記に示す本
発明方法で行なつた場合と従来法で行なつた場合
の、鋳片に生じたブレークアウト発生指数であ
る。
本発明方法
鋳片引抜速度（Vc）：0.7ｍ／分
鋳型の形状：弱テーパ
鋳型の振動波形：非正弦波（α＝40％）
従来例 １
鋳片引抜速度（Vc）：0.9ｍ／分
鋳型の形状：弱テーパ
鋳型の振動波形：正弦波
従来例 ２
鋳片引抜速度（Vc）：0.7ｍ／分
鋳型の形状：弱テーパ
鋳型の振動波形：正弦波
第９図から明らかなように、本発明方法によれ
ば、ブレークアウト発生指数は、従来例２の場合
に比べて約４分の１に低減し、安定した鋳造を行
なうことができた。このようにブレークアウト発
生指数が低減したのは、鋳型の振動波形を非正弦
波としたことにより、前述した摩擦力指数が40％
低減したことによるものと考えられる。
〔発明の効果〕
以上述べたように、この発明の方法によれば、
炭素含有量が0.08〜0.16wt.％の炭素鋼またはクロ
ム含有量が17wt.％のステンレス鋼（SUS 430）
を連続鋳造するに当り、鋳片の表面性状が改善さ
れ、鋳片の表層に爪が発生せず、鋳片に割れやシ
エルの破断が生ぜず、しかも鋳造速度を落すこと
なく高能率で鋳造することができる工業上優れた
効果がもたらされる。[Table] Figure 6A shows the transverse crack occurrence index (number of transverse cracks ÷ unit area ( This is a graph showing m 2 )). Method of the present invention Slab drawing speed (Vc): 1.0 m/min Mold shape: Weak taper Mold vibration waveform: Non-sinusoidal wave (α = 40%) Negative stripping time: 0.173 seconds Conventional example 1 Mold drawing speed ( Vc): 1.0 m/min Mold shape: Strong taper Mold vibration waveform: Sine wave Negative stripping time: 0.222 seconds Conventional example 2 Slab drawing speed (Vc): 0.8 m/min Mold shape: Strong taper mold Vibration waveform: Sine wave Negative stripping time: 0.238 seconds Conventional example 3 Slab drawing speed (Vc): 0.8 m/min Mold shape: Weak taper Mold vibration waveform: Sine wave Negative stripping time: 0.238 seconds In the above, strong taper refers to the taper T from the upper end to the lower end of the mold 1 shown in FIG.
(A-B/A×1001/L)% is 0.8%/m, and a weak taper is defined as T being 0.65%/m. As is clear from FIG. 6A, in the case of the method of the present invention, even when the slab drawing speed is high at 1.0 m/min, the horizontal crack occurrence index of the slab is extremely low, and the This was almost the same as when the speed was set to 0.8 m/min and a slightly tapered mold was used, and the production efficiency was improved by about 20% compared to Conventional Example 3. FIG. 6B is a graph showing the transverse crack occurrence index that occurs in slabs when continuous casting is performed while changing the strain rate (α) of the waveform within the range of 0 to 50%. As is clear from FIG. 6B, when the strain rate (α) was increased to 20% or more, the transverse crack occurrence index decreased significantly. FIG. 7 is a graph showing the relationship between the strain rate of the vibration waveform of the mold and the frequency of occurrence of claws in the valleys of the oscillation marks of the slab. In general, the oscillation marks that occur on carbon steel slabs include those where claws are formed in the valleys of the oscillation marks and are accompanied by segregation lines, as shown in Figure 8a, and those with segregation lines as shown in Figure 8b. In some cases, there are no segregation lines where no nails appear in the valleys of the oscillation marks. Such claws receive tensile stress on the upper surface of the slab during slab straightening when cast by a curved continuous casting machine, causing horizontal cracks to occur along the jaws or valleys. . As is clear from Fig. 7, the frequency of occurrence of the above-mentioned claws is 45 to 50% when the distortion rate of the vibration waveform of the mold is 0% (sine waveform), but when the distortion rate is 20%.
For non-sinusoidal waveforms, the distortion rate is approximately 35%, and the above distortion is 40%.
In the case of a non-sinusoidal waveform, it was approximately 20%, and it was possible to significantly reduce horizontal cracking of slabs caused by claws. Example 2 Next, the mold was set at a vibration stroke of 8 mm and a vibration frequency of
Stainless steel (SUS) with a Cr content of 17 wt.
430) was continuously cast, and a slab with a thickness of 250 mm and a width of 1500 mm was cast. FIG. 9 shows the breakout occurrence index that occurred in slabs when the above casting was performed by the method of the present invention shown below and by the conventional method. Method of the present invention Slab drawing speed (Vc): 0.7 m/min Mold shape: Slight taper Vibration waveform of mold: Non-sinusoidal wave (α = 40%) Conventional example 1 Slab drawing speed (Vc): 0.9 m/min Mold shape: Vibration waveform of weak taper mold: Sine wave Conventional example 2 Slab drawing speed (Vc): 0.7 m/min Mold shape: Vibration waveform of weak taper mold: Sine wave As is clear from Figure 9, According to the method of the present invention, the breakout occurrence index was reduced to about one quarter of that in Conventional Example 2, and stable casting could be performed. This reduction in the breakout occurrence index is due to the non-sinusoidal vibration waveform of the mold, which reduces the frictional force index by 40%.
This is thought to be due to the reduction in [Effects of the invention] As described above, according to the method of this invention,
Carbon steel with a carbon content of 0.08~0.16wt.% or stainless steel with a chromium content of 17wt.% (SUS 430)
During continuous casting, the surface properties of the slab are improved, no claws occur on the surface layer of the slab, no cracks in the slab or breakage of the shell, and high efficiency casting is possible without slowing down the casting speed. It brings about excellent industrial effects.
第１図はこの発明の方法の一実施態様を示す鋳
型の振動波形を示すグラフ、第２図は同じく鋳型
の振動速度を示すグラフ、第３図は従来の鋳型の
振動波形を示すグラフ、第４図は同じく鋳型の振
動速度を示すグラフ、第５図は鋳型の振動波形の
歪率と摩擦力指数との関係を示すグラフ、第６図
Ａは炭素鋼を本発明方法で連続鋳造したときの鋳
片に生じた横割れ発生指数を従来法の場合と比較
して示すグラフ、第６図Ｂは振動波形の歪率と横
割れ発生指数との関係を示すグラフ、第７図は鋳
型振動波形の歪率と鋳片のオツシレーシヨンマー
クの谷部に生ずる爪の発生頻度との関係を示すグ
ラフ、第８図はオツシレーシヨンマークの形状を
示す図、第９図はステンレス鋼を本発明方法で連
続鋳造したときのブレークアウト発生指数を従来
法の場合と比較して示すグラフ、第１０図は炭素
鋼の連続鋳造時に鋳型とシエルとの間に生ずる空
〓を示す図、第１１図は鋳片に生ずる割れの形状
を示す図、第１２図は鋳型の形状を示す図、第１
３図はステンレス鋼の引張り強さと絞り値との関
係を示すグラフである。
図面において、１……鋳型、２……シエル、３
……空〓、４……鋳片、５，６，７……割れ。
FIG. 1 is a graph showing the vibration waveform of a mold showing an embodiment of the method of the present invention, FIG. 2 is a graph showing the vibration speed of the mold, FIG. 3 is a graph showing the vibration waveform of a conventional mold, and FIG. Figure 4 is a graph showing the vibration speed of the mold, Figure 5 is a graph showing the relationship between the strain rate of the vibration waveform of the mold and the friction force index, and Figure 6A is a graph when carbon steel is continuously cast using the method of the present invention. Figure 6B is a graph showing the relationship between the strain rate of the vibration waveform and the horizontal crack occurrence index, and Figure 7 is a graph showing the relationship between the vibration waveform strain rate and the horizontal crack occurrence index. A graph showing the relationship between the distortion rate of the waveform and the frequency of occurrence of claws that occur in the valleys of the oscillation marks on slabs. Figure 8 shows the shape of the oscillation marks. A graph showing the breakout occurrence index when continuous casting is carried out using the invention method compared to that of the conventional method. Fig. 10 is a drawing showing the air space created between the mold and the shell during continuous casting of carbon steel. Fig. 11 Figure 12 shows the shape of cracks that occur in slabs, Figure 12 shows the shape of the mold, Figure 1 shows the shape of the mold,
Figure 3 is a graph showing the relationship between the tensile strength and the aperture value of stainless steel. In the drawings, 1...Mold, 2...Ciel, 3
...Empty, 4...Slab, 5,6,7...Cracked.
Claims (1)
がら、前記鋳型から鋳片を所定速度で引抜くこと
により連続鋳造鋳片を製造するに当たり、 前記鋳型をゆつくりと上昇させた後、急速に下
降させることによる、下記式により表わされる振
動波形の歪率（α）が20％以上の非正弦波形によ
つて、前記鋳型を振動させ、かくして、前記鋳片
の表面性状を改善することを特徴とする、連続鋳
造鋳片の表面性状改善方法。 α＝Ｂ／Ａ×100（％） 但し、 α：振動波形の歪率 Ａ：正弦波形の、鋳型上死点から中立点までの時
間（sec） Ｂ：非正弦波形の鋳型上死点の、正弦波形のとき
の鋳型上死点からのずれを示す時間（sec）[Scope of Claims] 1. When producing a continuously cast slab by pulling the slab from the mold at a predetermined speed while vibrating the mold vertically at a constant pitch, the mold is slowly raised. After that, the mold is vibrated by a non-sinusoidal waveform with a distortion rate (α) of 20% or more expressed by the following formula by rapidly lowering the mold, thus changing the surface texture of the slab. A method for improving the surface properties of continuously cast slabs. α=B/A×100 (%) However, α: Distortion rate of vibration waveform A: Time from top dead center of mold to neutral point of sinusoidal waveform (sec) B: Time of mold top dead center of non-sinusoidal waveform, Time (sec) indicating deviation from mold top dead center when sinusoidal waveform
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP41485A JPS61162256A (en) | 1985-01-08 | 1985-01-08 | Improvement of surface characteristic of continuous casting steel ingot |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP41485A JPS61162256A (en) | 1985-01-08 | 1985-01-08 | Improvement of surface characteristic of continuous casting steel ingot |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61162256A JPS61162256A (en) | 1986-07-22 |
| JPH0356824B2 true JPH0356824B2 (en) | 1991-08-29 |
Family
ID=11473135
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP41485A Granted JPS61162256A (en) | 1985-01-08 | 1985-01-08 | Improvement of surface characteristic of continuous casting steel ingot |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61162256A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2032609T3 (en) * | 1988-01-28 | 1993-02-16 | Clecim | PROCEDURE AND DEVICE FOR THE OSCILLATION OF A CONTINUOUS STEEL CAST INGING MACHINE. |
| JPH04172161A (en) * | 1990-11-05 | 1992-06-19 | Nkk Corp | Method for continuously casting cast slab having beautiful surface |
| US5823245A (en) * | 1992-03-31 | 1998-10-20 | Clecim | Strand casting process |
| DE69616567T2 (en) * | 1995-08-25 | 2002-06-27 | Sidmar Nv | SWINGING TABLE, ESPECIALLY FOR USE IN A CONTINUOUS CASTING SYSTEM |
| CN109807297B (en) * | 2019-02-27 | 2020-01-14 | 燕山大学 | Non-sinusoidal vibration method for continuous casting crystallizer |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS583755A (en) * | 1981-06-30 | 1983-01-10 | Kawasaki Steel Corp | Preventing method for cracking of side surface of continuously cast slab |
| JPS5838646A (en) * | 1981-08-31 | 1983-03-07 | Kawasaki Steel Corp | Continuous casting method for slab of middle carbon region steel |
-
1985
- 1985-01-08 JP JP41485A patent/JPS61162256A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS583755A (en) * | 1981-06-30 | 1983-01-10 | Kawasaki Steel Corp | Preventing method for cracking of side surface of continuously cast slab |
| JPS5838646A (en) * | 1981-08-31 | 1983-03-07 | Kawasaki Steel Corp | Continuous casting method for slab of middle carbon region steel |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61162256A (en) | 1986-07-22 |
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