JPH05220556A - Continuous casting method - Google Patents
Continuous casting methodInfo
- Publication number
- JPH05220556A JPH05220556A JP5720592A JP5720592A JPH05220556A JP H05220556 A JPH05220556 A JP H05220556A JP 5720592 A JP5720592 A JP 5720592A JP 5720592 A JP5720592 A JP 5720592A JP H05220556 A JPH05220556 A JP H05220556A
- Authority
- JP
- Japan
- Prior art keywords
- slab
- segregation
- continuous casting
- deteriorated
- casting method
- 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.)
- Granted
Links
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、連続鋳造鋳片の厚み中
心部に見られる不純物元素、即ち鋼鋳片の場合には硫
黄、燐、マンガン等の偏析を防止し、均質な金属を得る
ことのできる連続鋳造法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents segregation of impurity elements found in the center of thickness of continuously cast slabs, that is, in the case of steel slabs, segregation of sulfur, phosphorus, manganese and the like to obtain a homogeneous metal. The present invention relates to a continuous casting method that can be performed.
【0002】[0002]
【従来の技術】近年、海洋構造物、貯槽、石油およびガ
ス運搬用鋼管、ならびに抗張力線材などの材質特性に対
する要求は厳しさを増しており、均質な鋼材を提供する
ことが重要課題になっている。元来鋼材は断面内におい
て均質であるべきであるが、鋼は一般に硫黄、燐、マン
ガン等の不純物元素を含有しており、これらが鋳造過程
において偏析し、部分的に濃化するため脆弱となる。特
に近年、生産性や歩留り向上および省エネルギー等の目
的のために連続鋳造法が一般的に普及しているが、連続
鋳造により得られる鋳片の厚み中心近傍には、通常顕著
な成分偏析が観察される。この成分偏析は最終成品の均
質性を著しく損ない、成品の使用過程や線材の線引き工
程等で鋼に作用する応力により亀裂が発生するなど重大
欠陥の原因となるため、その低減が切望されている。2. Description of the Related Art In recent years, the demands on the material characteristics of offshore structures, storage tanks, steel pipes for oil and gas transportation, and tensile strength wire rods have become stricter, and it has become an important issue to provide homogeneous steel rods. There is. Originally, steel should be homogeneous in the cross section, but steel generally contains impurity elements such as sulfur, phosphorus, and manganese, which segregate during the casting process and become partially concentrated, resulting in brittleness. Become. Especially in recent years, the continuous casting method has been widely used for the purpose of improving productivity, yield improvement, and energy saving, but usually noticeable segregation of components is observed in the vicinity of the thickness center of the slab obtained by continuous casting. To be done. This component segregation seriously impairs the homogeneity of the final product and causes serious defects such as cracks due to stress acting on the steel during the use process of the product and the wire drawing process of the wire rod. .
【0003】かかる成分偏析は、凝固末期に残溶鋼が凝
固収縮力等により流動し、固液界面近傍の濃化溶鋼を洗
い出し、残溶鋼が累進的に濃化していくため発生すると
考えられている。従って、成分偏析を防止するには残溶
鋼の流動原因を取り除くことが肝要である。It is believed that such component segregation occurs because the residual molten steel flows at the end of solidification due to solidification shrinkage force and the like, the concentrated molten steel near the solid-liquid interface is washed out, and the residual molten steel progressively thickens. .. Therefore, in order to prevent the segregation of the components, it is important to eliminate the cause of the flow of the residual molten steel.
【0004】このような流動原因としては、凝固収縮に
起因する流動のほか、ロール間の鋳片バルジングやロー
ルアライメント不整に起因する流動等があるが、これら
のうち最も重大な原因は凝固収縮であり、偏析を防止す
るためにはこれを補償する量だけ鋳片を圧下することが
必要である。As such a cause of flow, in addition to a flow caused by solidification shrinkage, there is a slab bulging between rolls and a flow caused by roll alignment irregularity. Among these, the most serious cause is solidification shrinkage. Therefore, in order to prevent segregation, it is necessary to roll down the slab by an amount that compensates for this.
【0005】鋳片を圧下することにより偏析を改善する
試みは従来より行われており、連続鋳造工程において鋳
片中心部温度が液相線温度から固相線温度にいたるまで
の間、鋳片の凝固収縮を補償する量以上の一定割合で圧
下する方法が知られている。しかしながら従来の連続鋳
造法は、条件によっては偏析改善が殆ど認められなかっ
たり、場合によっては偏析がかえって悪化する等の問題
があり、成分偏析を充分に改善することは困難であっ
た。Attempts have been made to improve segregation by rolling down the slab, and in the continuous casting process, the slab is cooled from the liquidus temperature to the solidus temperature until the slab center temperature rises from the liquidus temperature to the solidus temperature. There is known a method of rolling at a constant rate above the amount that compensates for the solidification shrinkage of. However, the conventional continuous casting method has a problem that the segregation is hardly improved depending on the conditions, or the segregation is rather deteriorated in some cases, and it is difficult to sufficiently improve the segregation of the components.
【0006】また、これらの偏析悪化理由を研究し、鋳
片の中心部が固相率0.1〜0.3に相当する温度にな
る時点から流動限界固相率に相当する温度となる時点ま
での領域を単位時間当り0.5mm/分以上2.5mm
/分未満の割合で連続的に圧下し、鋳片中心部が流動限
界固相率に相当する温度となる時点から固相線温度とな
るまでの領域は実質的に圧下を加えないようにする特願
昭62−27556号に係る方法が良く知られている。Further, by studying the reason for the deterioration of segregation, the time when the temperature of the central portion of the slab reaches the temperature corresponding to the solid fraction of 0.1 to 0.3 is reached. Area up to 0.5 mm / min or more per unit time of 2.5 mm
It is continuously reduced at a rate of less than 1 minute, and the region from the time when the temperature of the core of the slab reaches the solidification rate limit to the solidus temperature is not substantially reduced. The method according to Japanese Patent Application No. 62-27556 is well known.
【0007】さらに、本発明者等が先に特願平1−12
0295号において提示したごとく、濃化溶鋼が激しく
鋳片の中心部に集積する凝固時期が存在し、この濃化溶
鋼の集積時期の流動を防止することが偏析改善にとって
最も効果的であり、また濃化溶鋼の集積量が特に多い凝
固時期は凝固組織によって異なる。この結果に基づき偏
析をさらに改善する軽圧下法について研究した結果、凝
固末期に少なくとも一対のロールにより鋳片を圧下しつ
つ引き抜く溶融金属の連続鋳造法において、上面等軸晶
率0〜5%の場合、鋳片中心部の温度が固相率0.2
5、好ましくは0.35に相当する位置から流動限界固
相率に相当する位置までの凝固時期範囲の任意の位置、
好ましくは該凝固時期範囲内の上流側に少なくとも一対
のロールを設置して、該凝固時期範囲内の全凝固収縮量
を補償する量を圧下し、また上面等軸晶率が5%以上の
場合、鋳片中心部の温度が固相率0.1、好ましくは
0.15に相当する位置から流動限界固相率に相当する
位置までの凝固時期範囲の任意の位置、好ましくは該凝
固時期範囲内の上流側に少なくとも一対のロールを設置
して該凝固時期範囲内の全凝固収縮量を補償する量を圧
下する圧下範囲を小さくすることが可能な簡便で効率的
な軽圧下を提案した。Furthermore, the present inventors previously filed Japanese Patent Application No. 1-12.
As presented in No. 0295, there is a solidification time when the concentrated molten steel accumulates violently in the center of the slab, and preventing the flow of the concentrated molten steel during the accumulation time is the most effective for improving the segregation. The solidification timing at which the concentrated molten steel is particularly large depends on the solidification structure. Based on this result, as a result of research on a light reduction method for further improving segregation, in a continuous casting method of molten metal in which a slab is drawn while being pressed by at least a pair of rolls at the final stage of solidification, a top surface equiaxed crystal ratio of 0 to 5% is obtained. In this case, the temperature at the center of the slab is 0.2
5, preferably any position in the solidification time range from the position corresponding to 0.35 to the position corresponding to the flow limit solid fraction,
Preferably, at least a pair of rolls is installed on the upstream side in the solidification timing range to reduce the amount that compensates for the total solidification shrinkage amount in the solidification timing range, and the upper surface equiaxed crystal ratio is 5% or more. , Any position in the solidification time range from the position where the temperature of the central part of the slab corresponds to the solid phase ratio of 0.1, preferably 0.15 to the position corresponding to the flow limit solid phase ratio, preferably the solidification time range At least a pair of rolls is installed on the upstream side of the inside, and a simple and efficient light reduction is proposed in which the reduction range for reducing the amount for compensating the total amount of solidification shrinkage within the solidification timing range can be reduced.
【0008】[0008]
【発明が解決しようとする課題】しかしながら、連続鋳
造作業において鋳造速度の減速は避けることができず、
この鋳造速度減速の結果、偏析が悪化する鋳片が存在す
ることが多くの実験から明らかになってきた。このよう
に軽圧下による偏析改善効果が不充分な鋳片を出発材と
する線材のトラブルを防止するためには、偏析が最も悪
い部位においてもトラブルの発生を避けるため分塊加熱
条件を高温、長時間にする必要がある。このため、偏析
が良好な定常部鋳片に対しオーバーアクションとなり、
また高温加熱においては加熱炉における鉄ロスおよび脱
炭層の発生などの歩留りの低減や、作業性の悪化などの
問題が発生し、これらの解決が重要課題である。However, the reduction of the casting speed is unavoidable in the continuous casting operation,
As a result of this reduction in casting speed, it has become clear from many experiments that there are slabs in which segregation deteriorates. As described above, in order to prevent the trouble of the wire rod whose starting material is the ingot with insufficient segregation improving effect due to the light reduction, in order to avoid the occurrence of trouble even in the worst segregation area, the slab heating condition is set to a high temperature, Need to be long. For this reason, over-action occurs on the slab of steady part with good segregation,
Further, in high temperature heating, there are problems such as reduction of yield such as iron loss and generation of decarburized layer in the heating furnace and deterioration of workability, and solving these problems is an important issue.
【0009】[0009]
【課題を解決するための手段】本発明の要旨は以下の通
りである。The gist of the present invention is as follows.
【0010】 1対以上のロールにより鋳片を圧下し
つつ引き抜く溶融金属の連続鋳造法において、鋳造速度
の減速に起因した偏析悪化鋳片を鋳造速度が減速した時
の鋳片の凝固時期により判定して偏析レベルに応じた分
塊加熱条件および工程を選択することを特徴とする連続
鋳造法。In a continuous casting method of molten metal in which a slab is drawn out while being rolled down by one or more pairs of rolls, segregation-deteriorated slab due to slowing of the casting speed is judged by the solidification timing of the slab when the casting speed is slowed down. Then, the continuous casting method is characterized in that slab heating conditions and processes are selected according to the segregation level.
【0011】 1対以上のロールにより鋳片を圧下し
つつ引き抜く溶融金属の連続鋳造法において、鋳造速度
の減速に起因した偏析悪化鋳片を鋳造速度が減速した時
の鋳片の中心固相率により判定して偏析レベルに応じた
分塊加熱条件および工程を選択することを特徴とする連
続鋳造法。In a continuous casting method of molten metal in which a slab is drawn out while being rolled down by one or more pairs of rolls, segregation deteriorated due to slowing of the casting speed The solid phase fraction of the slab when the casting speed is reduced The continuous casting method is characterized by selecting the slab heating condition and process according to the segregation level.
【0012】 1対以上のロールにより鋳片を圧下し
つつ引き抜く溶融金属の連続鋳造法において、鋳造速度
減速時の凝固時期の一部あるいは全部が中心固相率で
0.15〜0.40の範囲にある偏析悪化鋳片の分塊加
熱条件を高温長時間とし、その他の偏析良好鋳片の分塊
加熱条件を低温短時間とすることを特徴とする連続鋳造
法。In a continuous casting method for molten metal in which a slab is drawn while being rolled down by one or more pairs of rolls, a part or all of the solidification time when the casting speed is decelerated is 0.15 to 0.40 as a central solid fraction. A continuous casting method, characterized in that the slab heating conditions for segregation-deteriorated slabs within the range are high temperature and long time, and the slab heating conditions for other segregated good slabs are low temperature and short time.
【0013】 1対以上のロールにより鋳片を圧下し
つつ引き抜く溶融金属の連続鋳造法において、予め鋳造
速度減速試験を行い、偏析悪化鋳片の減速時の中心固相
率を定量化し、この結果を用いて偏析悪化鋳片を判定し
て偏析レベルに応じた分塊加熱条件および工程を選択す
ることを特徴とする連続鋳造法。In a continuous casting method of molten metal in which a slab is drawn out while being rolled down by one or more pairs of rolls, a casting speed deceleration test is performed in advance to quantify the central solid fraction at the time of deceleration of the segregation-deteriorated slab. A continuous casting method characterized in that a slab with deteriorated segregation is determined by using and the slab heating condition and process are selected according to the segregation level.
【0014】 鋳造速度減速時の凝固時期の一部ある
いは全部が中心固相率で予め測定し決定した偏析悪化鋳
片の中心固相率の範囲にある偏析悪化鋳片の分塊加熱条
件を高温長時間とし、その他の偏析良好鋳片の分塊加熱
条件を低温短時間とする前記の連続鋳造法。A part or all of the solidification time when the casting speed is decelerated is measured by the central solid fraction in advance and determined to be within the range of the central solid fraction of the segregation deteriorated slab. The continuous casting method described above in which the slab heating conditions for other slabs with good segregation are set to low temperature and short time for a long time.
【0015】[0015]
【作用】以下、本発明を細述する。The present invention will be described in detail below.
【0016】軽圧下は偏析改善対策として非常に有効で
ある。しかしながら、この偏析改善効果は鋳造速度の減
速により小さくなり、減速の影響を受けた鋳片の中には
定常部と比べ偏析が悪化する鋳片が見られる。このよう
な鋳造速度の減速による偏析の悪化を防止するための第
一の対策は、鋳造速度一定の操業を実現することであ
る。しかし、連鋳操業において鋳造速度一定の操業を確
実に実現することは非常に困難である。この様な実態を
踏まえた第二の対策は、鋳造速度が減速した場合の偏析
悪化鋳片を正確に選択、分離して、偏析良好な鋳片の分
塊加熱条件を低温、短時間とし、偏析悪化鋳片の分塊加
熱条件を従来と同じように高温、長時間にすることであ
る。この技術を実現するためには、鋳造速度の減速に伴
う偏析悪化鋳片を選択する方法の確立が重要課題とな
る。The light reduction is very effective as a measure for improving the segregation. However, this effect of improving segregation becomes smaller due to the deceleration of the casting speed, and some of the slabs affected by the deceleration have the segregation worse than in the steady part. The first measure for preventing the segregation from deteriorating due to the reduction of the casting speed is to realize an operation at a constant casting speed. However, it is very difficult to reliably realize a constant casting speed operation in continuous casting operation. A second countermeasure based on such an actual situation is to accurately select and separate segregation-deteriorating cast pieces when the casting speed is reduced, and to set the segregation good slab heating conditions to a low temperature for a short time, The segregation-deteriorating cast slab is heated at a high temperature for a long time as in the conventional case. In order to realize this technique, it is important to establish a method for selecting a slab with segregation that is deteriorated as the casting speed is reduced.
【0017】かかる課題を解決するため、本発明者らは
図1に示す鋳造速度の減速パターンで鋳造した場合の偏
析の悪化機構を試験研究した結果、図2に示すように、
鋳造速度の減速に伴う偏析悪化鋳片は、鋳造速度の減速
時に連鋳機内に位置した鋳片の中で特定な凝固時期にあ
った鋳片(偏析悪化部)と、モールドから圧下帯入口
の間に位置していた鋳片(偏析悪化部)であることを
知見した。さらに研究を進めた結果、これらの偏析悪化
鋳片の内、モールドから圧下帯入口の間に位置する鋳片
(偏析悪化部)の偏析悪化は特願平3−103939
号に示すごとく圧下パターン等の圧下条件を適正化する
ことにより改善できることを知見した。圧下条件を適正
化した場合、鋳造速度減速に伴う偏析悪化鋳片は減速時
に特定な凝固時期にあった鋳片(偏析悪化部)のみに
なる。この偏析悪化鋳片の凝固履歴を検討した結果、偏
析悪化鋳片は鋳造速度減速時に図3に示すように凝固時
期が中心固相率で0.15〜0.40の範囲にある鋳片
で、減速に伴う偏析悪化鋳片は図4に示すように分離で
きることを知見し本発明を成し遂げた。In order to solve such a problem, the inventors of the present invention have conducted a test study on the mechanism of deterioration of segregation when casting is performed with a deceleration pattern of the casting speed shown in FIG. 1, and as a result, as shown in FIG.
The segregation deteriorated slab due to the slowing of the casting speed, the slab that was in a specific solidification time among the slabs located in the continuous casting machine when the casting speed was decelerated (segregation deterioration part) It was found that it was a cast piece (segregation-deteriorated portion) located between them. As a result of further research, the segregation deterioration of the slab (segregation deterioration part) located between the mold and the draft zone inlet among these segregation deterioration slabs was found in Japanese Patent Application No. 3-103939.
It was found that this can be improved by optimizing the rolling conditions such as rolling pattern as shown in No. When the reduction condition is optimized, the segregation deteriorated due to the deceleration of the casting speed is only the segregation (segregation deteriorated part) at a specific solidification time during deceleration. As a result of examining the solidification history of this segregation-deteriorated slab, the segregation-deteriorated slab is a slab whose solidification time is in the range of 0.15 to 0.40 in terms of the central solid fraction as shown in FIG. The present invention has been accomplished by finding that a slab that has deteriorated in segregation due to deceleration can be separated as shown in FIG.
【0018】さらに本発明者らが研究を進めた結果、鋳
造速度の減速により偏析が悪化する鋳片の減速時の凝固
時期は、表1に示すように凝固組織や鋼種、鋳片形状に
より異なっていることを知見した。従って、偏析悪化鋳
片を精度良く分離するためには、対象とする鋼種、凝固
組織、鋳片形状に対し、鋳造速度減速試験により偏析悪
化鋳片の凝固時期を予め定量化しておくことが好まし
い。このように選択した偏析悪化鋳片を分離して、偏析
良好な鋳片の分塊加熱条件を低温、短時間にすることに
より使用エネルギーおよび鉄歩留りの大幅な節約が可能
となり、品質の良い成品を安定して生産できる。As a result of further research by the present inventors, the solidification timing at the time of deceleration of a slab in which segregation deteriorates due to the reduction of the casting speed is different depending on the solidification structure, steel type and slab shape as shown in Table 1. I found that. Therefore, in order to accurately separate the segregation-deteriorated slab, it is preferable to quantify the solidification timing of the segregation-deteriorated slab by a casting speed deceleration test for the target steel type, solidification structure, and slab shape. . By separating the segregated slabs with deteriorated segregation selected in this way and reducing the slab heating conditions for the slabs with good segregation to a low temperature for a short time, it is possible to greatly reduce the energy used and the iron yield, and to obtain high quality products. Can be stably produced.
【0019】[0019]
【表1】 [Table 1]
【0020】なお、鋳片の凝固時期を中心固相率で示し
たのは、樹間濃化溶鋼の集積が始まると考えられる凝固
時期は鋳片中心部の通液抵抗が増大する凝固時期で、こ
の通液抵抗増大に対し、中心部の固相の割合を示す中心
固相率が最も影響を及ぼすと考えられるためで、偏析発
生の凝固時期を示す指標として最も適切である。中心固
相率は(1)式数1に示すように、鋳片中心部の温度の
関数として算出する。鋳片中心部の温度は冷却条件や鋳
造速度等の操業条件に基づき伝熱計算により予め計算す
るか、または鋳造中の冷却や鋳造速度等の条件に基づき
計算する。この中心固相率は鋳造速度、冷却条件、鋳片
サイズ、鋼種が決まれば凝固時間の関数であり、同じ凝
固時間の関数であるシェル厚、未凝固厚、未凝固率に容
易に換算することができる。The solidification time of the slab is indicated by the central solid fraction. The solidification time at which the thickening of the thickened molten steel is considered to start is the solidification time at which the liquid flow resistance at the center of the slab increases. It is considered that the central solid fraction, which indicates the proportion of the solid phase in the central portion, has the greatest effect on this increase in liquid flow resistance, and is therefore the most appropriate index for the solidification timing of segregation. The central solid fraction is calculated as a function of the temperature at the center of the slab, as shown in equation (1). The temperature of the center of the slab is calculated in advance by heat transfer calculation based on cooling conditions, operating conditions such as casting speed, or based on conditions such as cooling during casting and casting speed. This central solid fraction is a function of solidification time if the casting speed, cooling conditions, slab size, and steel type are determined, and can be easily converted to the same solidification time function of shell thickness, unsolidified thickness, and unsolidified ratio. You can
【0021】[0021]
【数1】 鋳片の中心固相率=(T1 −T)/(T1 −Ts ) (1) T1 :溶鋼の液相線温度 (℃) Ts :溶鋼の固相線温度 (℃) T :鋳片の中心温度 (℃)[Number 1] center of the slab solid fraction = (T 1 -T) / ( T 1 -T s) (1) T 1: molten steel liquidus temperature (℃) T s: solidus temperature of the molten steel (℃) T: Core temperature of the slab (℃)
【0022】次に、本発明を実施例により説明する。Next, the present invention will be described with reference to examples.
【0023】[0023]
【実施例1】試験を実施した連鋳機の概略を図5に示
す。圧下パターンは特願平3−103939号に示した
方法により設定した。鋳造した溶鋼組成の代表例を表2
に示す。図1に示す鋳造速度パターンで鋳造速度の減速
を図り、鋳造速度減速の偏析に及ぼす影響を調査した。
凝固組織は上面等軸晶率が30%であった。偏析が悪化
している鋳片は鋳造速度減速中の凝固時期が図3に示す
ように中心固相率で0.18〜0.32の範囲の鋳片で
あった。図6は本法により鋳片を選択、分離せず、鋳片
全量を低温短時間の分塊加熱条件により圧延した場合を
示す。全量を低温、短時間の分塊加熱条件で圧延した場
合、線材に偏析が観察される例がある。一方、図7は減
速中の凝固時期が中心固相率で0.18〜0.32の鋳
片の分塊加熱条件を高温、長時間とし、それ以外の偏析
良好な鋳片の分塊加熱条件を低温、短時間とした場合の
線材偏析を示す。線材偏析は全量とも良好となり、使用
エネルギーの節約と歩留りの改善、および品質の安定化
が実現できた。Example 1 FIG. 5 shows an outline of a continuous casting machine that has been tested. The rolling reduction pattern was set by the method described in Japanese Patent Application No. 3-103939. Typical examples of cast molten steel composition
Shown in. With the casting speed pattern shown in FIG. 1, the casting speed was decelerated, and the effect of the casting speed deceleration on segregation was investigated.
The solidified structure had an upper surface equiaxed crystal ratio of 30%. As for the slab in which the segregation was deteriorated, the solidification time during deceleration of the casting speed was a slab with a central solid fraction of 0.18 to 0.32 as shown in FIG. FIG. 6 shows the case where the slab is not selected and separated by this method, and the entire amount of the slab is rolled under the slab heating conditions at a low temperature for a short time. When the whole amount is rolled under a slab heating condition at a low temperature for a short time, segregation may be observed in the wire. On the other hand, FIG. 7 shows that the slab heating conditions for the slabs whose solidification time during deceleration is 0.18 to 0.32 at the central solid phase rate are high temperature and long time, and slab heating for other slabs with good segregation. The segregation of the wire when the conditions are low temperature and short time is shown. The segregation of all the wire rods was good, saving energy consumption, improving yield, and stabilizing quality.
【0024】[0024]
【表2】 [Table 2]
【0025】[0025]
【実施例2】種々の凝固組織、鋼種、鋳片形状について
実施例1と同じ方法により鋳造速度減速試験を行った。
鋳造速度の減速に伴い偏析が悪化する鋳片は、実施例1
と同じ様に、表1に示すように鋳造速度減速時に特定な
凝固時期にあった鋳片で、偏析悪化鋳片の減速時の凝固
時間は鋼種、凝固組織、鋳片形状で差が認められた。こ
のように選択した偏析悪化鋳片の分塊加熱条件を従来通
り高温、長時間とし、また偏析良好な鋳片の分塊加熱条
件を低温、短時間とすることにより、使用エネルギーの
節約と鉄歩留りの改善、および品質の安定化が実現でき
た。[Example 2] A casting speed deceleration test was conducted on various solidified structures, steel types, and slab shapes by the same method as in Example 1.
The slab in which segregation deteriorates as the casting speed decreases is shown in Example 1.
Similarly, as shown in Table 1, in the case of a cast piece having a specific solidification time when the casting speed was decelerated, the segregation deterioration deteriorated, and the solidification time during deceleration of the cast piece differed depending on the steel type, solidification structure, and shape of the cast piece. It was In this way, the slab heating conditions for segregation-deteriorated slabs selected in this way are kept at high temperature for a long time as before, and the slab heating conditions for slabs with good segregation are set at a low temperature for a short time, thus saving energy consumption and iron. We were able to improve yield and stabilize quality.
【0026】[0026]
【発明の効果】本発明により、鋳造速度の減速に起因し
た軽圧下による偏析改善効果が不充分な鋳片を分離する
ことが可能となり、偏析レベルに応じた分塊加熱条件お
よび工程を選択することにより、従来より少ないエネル
ギーで鉄歩留り良好でかつ均質な鋼材を得ることが可能
となる。EFFECTS OF THE INVENTION According to the present invention, it becomes possible to separate a slab with insufficient segregation improving effect due to light reduction due to the reduction of casting speed, and the slab heating conditions and steps are selected according to the segregation level. As a result, it is possible to obtain a steel material having a good iron yield and a uniform steel material with less energy than conventional ones.
【図1】試験を実施した鋳造速度の減速パターンを示す
図である。FIG. 1 is a diagram showing a deceleration pattern of a casting speed in which a test is performed.
【図2】減速開始時の鋳造長さと偏析の関係を示す図で
ある。FIG. 2 is a diagram showing the relationship between casting length and segregation at the start of deceleration.
【図3】鋳造速度減速に伴い偏析が悪化した鋳片の減速
時の中心固相率を示す図である。FIG. 3 is a diagram showing a central solid fraction at the time of deceleration of a cast piece in which segregation is deteriorated as the casting speed is decelerated.
【図4】鋳造速度減速に伴う偏析悪化鋳片の分離方法を
示す図である。FIG. 4 is a diagram showing a method of separating a slab that is deteriorated in segregation due to a reduction in casting speed.
【図5】試験を実施した連鋳機の概略を示す図である。FIG. 5 is a diagram showing an outline of a continuous casting machine that has been tested.
【図6】鋳片の全量を従来より低温、短時間の分塊加熱
条件で圧延した場合の線材偏析を示す図である。FIG. 6 is a diagram showing segregation of wire rods when the entire amount of cast slab is rolled under a slab heating condition at a lower temperature for a shorter time than conventional.
【図7】本法で偏析悪化鋳片を判別し、偏析悪化鋳片を
従来の高温長時間分塊加熱条件とし、偏析良好鋳片の分
塊加熱条件を低温短時間にした場合の線材偏析を示す図
である。FIG. 7: A segregation-deteriorated slab is identified by this method, and the segregation-deteriorated slab is subjected to conventional high-temperature long-time slab heating conditions, and segregation-satisfactory segregation slab is heated at a low temperature for a short time. FIG.
Claims (5)
つ引き抜く溶融金属の連続鋳造法において、鋳造速度の
減速に起因した偏析悪化鋳片を鋳造速度が減速した時の
鋳片の凝固時期により判定して偏析レベルに応じた分塊
加熱条件および工程を選択することを特徴とする連続鋳
造法。1. In a continuous casting method of molten metal in which a slab is drawn out while being rolled down by one or more pairs of rolls, the segregation time of the slab when the casting speed is reduced when the casting speed is reduced The continuous casting method is characterized by selecting the slab heating condition and process according to the segregation level.
つ引き抜く溶融金属の連続鋳造法において、鋳造速度の
減速に起因した偏析悪化鋳片を鋳造速度が減速した時の
鋳片の中心固相率により判定して偏析レベルに応じた分
塊加熱条件および工程を選択することを特徴とする連続
鋳造法。2. In a continuous casting method for molten metal, wherein a slab is drawn out while being rolled down by one or more pairs of rolls, segregation-deteriorated slab due to slowing of the casting speed causes the solid core of the slab to be cast when the casting speed is slowed down. A continuous casting method characterized by selecting slab heating conditions and steps according to the segregation level as judged by the phase ratio.
つ引き抜く溶融金属の連続鋳造法において、鋳造速度減
速時の凝固時期の一部あるいは全部が中心固相率で0.
15〜0.40の範囲にある偏析悪化鋳片の分塊加熱条
件を高温長時間とし、その他の偏析良好鋳片の分塊加熱
条件を低温短時間とすることを特徴とする連続鋳造法。3. In a continuous casting method for molten metal in which a slab is drawn while being rolled down by one or more pairs of rolls, a part or all of the solidification time when the casting speed is reduced is 0.
A continuous casting method characterized in that the slab heating conditions for segregation-deteriorated slabs in the range of 15 to 0.40 are high temperature and long time, and the slab heating conditions for other segregation-satisfactory slabs are low temperature and short time.
つ引き抜く溶融金属の連続鋳造法において、予め鋳造速
度減速試験を行い、偏析悪化鋳片の減速時の中心固相率
を定量化し、この結果を用いて偏析悪化鋳片を判定して
偏析レベルに応じた分塊加熱条件および工程を選択する
ことを特徴とする連続鋳造法。4. A continuous casting method for molten metal in which a slab is drawn while being pressed by a pair of rolls or more, a casting speed deceleration test is performed in advance to quantify the central solid fraction during deceleration of a segregation-deteriorated slab, A continuous casting method characterized by determining a segregation-deteriorated slab using this result and selecting a slab heating condition and process according to the segregation level.
は全部が中心固相率で予め測定し決定した偏析悪化鋳片
の中心固相率の範囲にある偏析悪化鋳片の分塊加熱条件
を高温長時間とし、その他の偏析良好鋳片の分塊加熱条
件を低温短時間とする請求項4記載の連続鋳造法。5. A slab heating condition for a segregation-deteriorated slab within a range of a center-solid fraction of a segregation-deteriorated slab which is determined by measuring a part or all of the solidification time when the casting speed is decelerated. 5. The continuous casting method according to claim 4, wherein the temperature is set to a high temperature for a long time, and the slab heating conditions for other slabs with good segregation are set to a low temperature for a short time.
Priority Applications (1)
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JP4057205A JP2593385B2 (en) | 1992-02-12 | 1992-02-12 | Continuous casting method |
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JP4057205A JP2593385B2 (en) | 1992-02-12 | 1992-02-12 | Continuous casting method |
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JP2593385B2 JP2593385B2 (en) | 1997-03-26 |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH05220557A (en) * | 1992-02-12 | 1993-08-31 | Nippon Steel Corp | Continuous casting method |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH02303661A (en) * | 1989-05-17 | 1990-12-17 | Nippon Steel Corp | Continuous casting method |
JPH04313454A (en) * | 1991-04-09 | 1992-11-05 | Nippon Steel Corp | Continuous casting method |
JPH04313453A (en) * | 1991-04-09 | 1992-11-05 | Nippon Steel Corp | Continuous casting method |
JPH05220557A (en) * | 1992-02-12 | 1993-08-31 | Nippon Steel Corp | Continuous casting method |
-
1992
- 1992-02-12 JP JP4057205A patent/JP2593385B2/en not_active Expired - Fee Related
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH02303661A (en) * | 1989-05-17 | 1990-12-17 | Nippon Steel Corp | Continuous casting method |
JPH04313454A (en) * | 1991-04-09 | 1992-11-05 | Nippon Steel Corp | Continuous casting method |
JPH04313453A (en) * | 1991-04-09 | 1992-11-05 | Nippon Steel Corp | Continuous casting method |
JPH05220557A (en) * | 1992-02-12 | 1993-08-31 | Nippon Steel Corp | Continuous casting method |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH05220557A (en) * | 1992-02-12 | 1993-08-31 | Nippon Steel Corp | Continuous casting method |
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