JPH11129060A - Manufacture of cast piece by continuous casting - Google Patents
Manufacture of cast piece by continuous castingInfo
- Publication number
- JPH11129060A JPH11129060A JP29573897A JP29573897A JPH11129060A JP H11129060 A JPH11129060 A JP H11129060A JP 29573897 A JP29573897 A JP 29573897A JP 29573897 A JP29573897 A JP 29573897A JP H11129060 A JPH11129060 A JP H11129060A
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- Japan
- Prior art keywords
- slab
- unsolidified
- reduction
- center
- less
- 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.)
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、炭素鋼、ステンレ
ス鋼および高合金鋼等の連続鋳造鋳片の製造方法、特に
中心偏析、センターポロシティおよび内部割れ等の内部
欠陥の少ない、断面形状の良好な鋳片の製造を可能とす
る連続鋳造鋳片の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing continuous cast slabs of carbon steel, stainless steel, high alloy steel, etc., and more particularly to a method of producing a cross-sectional shape having few internal defects such as center segregation, center porosity and internal cracks. The present invention relates to a method for producing a continuous cast slab which enables production of a simple cast slab.
【０００２】[0002]
【従来の技術】連続鋳造、特に鋼の連続鋳造において
は、鋳片の中心部に中心偏析やセンターポロシティ等の
内部欠陥が発生し問題となる。2. Description of the Related Art In continuous casting, particularly continuous casting of steel, internal defects such as center segregation and center porosity occur at the center of a slab, which is problematic.
【０００３】例えば、線材向けの鋳片に生じる中心偏析
およびセンターポロシティは伸線加工時に発生するカッ
ピー断線の原因となり、また、棒鋼においては押し出し
加工時に発生するシェブロンクラックの原因となる。ま
た、厚板用の鋳片の中心偏析およびセンターポロシティ
は、大入熱用継手部の靱性低下や、サワーガス輸送用大
径鋼管の水素誘起割れの原因となる。[0003] For example, center segregation and center porosity generated in a slab for a wire rod cause cut-off of a wire during wire drawing, and also cause chevron cracks during extrusion in a steel bar. In addition, the center segregation and center porosity of the slab for a thick plate cause a decrease in toughness of a joint part for large heat input and cause hydrogen-induced cracking of a large diameter steel pipe for sour gas transport.
【０００４】中心偏析は、鋳片の厚み方向中心部にＣ、
Ｓ、ＰおよびＭｎなどの溶鋼成分が濃化する現象であ
り、凝固進行にともない濃化したデンドライト間の残溶
鋼が、溶鋼の凝固収縮やロール間バルジング等の原因に
より最終凝固部である鋳片中心部に移動し集積すること
により発生すると考えられている。[0004] The center segregation is caused by C,
This is a phenomenon in which the molten steel components such as S, P and Mn are concentrated, and the residual molten steel between the dendrites that has been concentrated as the solidification progresses is a slab that is the final solidified part due to solidification shrinkage of the molten steel and bulging between rolls. It is thought to be caused by moving to the center and accumulating.
【０００５】また、センターポロシティは、凝固収縮が
原因で最終凝固部である鋳片中心部に生成する。したが
って、これらの対策として、濃化溶鋼である残溶鋼の移
動、集積を阻止し、また、凝固収縮によるセンターポロ
シティの発生を抑制するために、凝固完了点付近をロー
ルまたは金型などの手段で圧下する方法等の提案がなさ
れてきた。The center porosity is generated at the center of the slab, which is the final solidified portion, due to solidification shrinkage. Therefore, as a countermeasure against these problems, in order to prevent the movement and accumulation of the residual molten steel, which is concentrated molten steel, and to suppress the occurrence of center porosity due to solidification shrinkage, the area near the solidification completion point should be rolled or dies. There have been proposals for a method of rolling down.
【０００６】例えば、特開昭６３−２５２６５５号公報
には、鋳片表面に噴射される二次冷却水量を増量するこ
とにより、最終凝固部の表面温度を７００〜８００℃の
範囲とし、凝固シェル厚さを厚くすることによりロール
間で発生するバルジングを抑制し、さらに軽圧下ロール
群で毎分０．２〜０．４％の歪み速度の圧下を鋳片に加
えることにより残溶鋼の流動を阻止し、中心偏析を防止
する方法が提示されている。For example, Japanese Patent Application Laid-Open No. 63-252655 discloses that the surface temperature of a final solidified portion is set to a range of 700 to 800 ° C. by increasing the amount of secondary cooling water injected to the surface of a cast slab. The bulging generated between the rolls is suppressed by increasing the thickness, and the flow of the residual molten steel is reduced by applying a reduction of 0.2 to 0.4% per minute to the slab by a light reduction roll group. A method has been proposed to block and prevent center segregation.
【０００７】特開昭６１−４２４６０号公報には、凝固
完了点の上流側に設置した電磁攪拌装置あるいは超音波
印加装置を用いて溶鋼流動によりデンドライトを切断
し、凝固完了点付近に等軸晶を形成させた上で、凝固完
了点直前に配置した圧下ロールにより３ｍｍ以上の大圧
下を与えて強制的に凝固完了点を形成し、内部割れを発
生させることなく中心偏析を防止する方法が提示されて
いる。Japanese Patent Application Laid-Open No. 61-42460 discloses that dendrite is cut by molten steel flow using an electromagnetic stirrer or an ultrasonic wave applicator installed upstream of a solidification completion point, and an equiaxed crystal is formed near the solidification completion point. Is formed, and a large reduction of 3 mm or more is applied by a reduction roll placed immediately before the solidification completion point to forcibly form the solidification completion point, and a method of preventing center segregation without generating internal cracks is presented. Have been.
【０００８】また、特開平３−１２４３５２号公報に
は、鋳片の厚さの２〜５倍の直径のロールで凝固末期部
を圧下し、中心偏析やセンターポロシティを低減する方
法が提示されている。Further, Japanese Patent Application Laid-Open No. 3-124352 discloses a method of reducing the center segregation and center porosity by rolling down the end of solidification with a roll having a diameter 2 to 5 times the thickness of the slab. I have.
【０００９】[0009]
【発明が解決しようとする課題】しかしながら、特開昭
６３−２５２６５５号公報による方法では、鋳片の長手
方向に対して点状にしか圧下できないので、凝固収縮や
バルジングを充分に防止できず、中心偏析やセンターポ
ロシティの問題が残る。さらに、多数の圧下ロールを必
要とするため、設備費が高くなる問題もある。However, in the method disclosed in Japanese Patent Application Laid-Open No. 63-252655, the rolling can be reduced only in a point-wise manner in the longitudinal direction of the slab, so that solidification shrinkage and bulging cannot be sufficiently prevented. The problem of center segregation and center porosity remains. Furthermore, since a large number of reduction rolls are required, there is also a problem that equipment costs are increased.
【００１０】また、特開昭６１−４２４６０号公報や特
開平３−１２４３５２号公報による方法は、凝固完了前
の未凝固部を有する鋳片を圧下するため、特に断面形状
が円形である鋳片（以下、丸鋳片ともいう）や厚肉断面
の矩形鋳片の製造において、鋳片の内部割れが発生しや
すい。The method disclosed in JP-A-61-42460 or JP-A-3-124352 reduces a slab having an unsolidified portion before solidification is completed. In the production of a rectangular slab having a thick section (hereinafter, also referred to as a round slab) or a thick slab, internal slabs of the slab tend to occur.
【００１１】図１は、従来法で丸鋳片を圧下した場合の
内部割れの発生を示す模式図である。同図に示すよう
に、ロール１１で未凝固部１２を有する丸鋳片１３を圧
下すると、凝固界面１４に引張り応力が作用し内部割れ
１５が発生する。この内部割れ１５は、割れ部に濃化溶
鋼を吸引し正偏析線として観察される。特に、Ｃ濃度が
高い条鋼用や合金成分の濃度が高いパイプ等用の鋼種で
は、内部割れが発生し易く、品質欠陥を招く。FIG. 1 is a schematic view showing the occurrence of internal cracks when a round slab is reduced by a conventional method. As shown in FIG. 1, when a round cast piece 13 having an unsolidified portion 12 is rolled down by a roll 11, a tensile stress acts on a solidified interface 14 to generate an internal crack 15. This internal crack 15 is observed as a positive segregation line by sucking the concentrated molten steel into the crack. In particular, in steel types for steel bars with a high C concentration or pipes with a high alloy component concentration, internal cracks are likely to occur, leading to quality defects.
【００１２】さらに、丸鋳片１３を圧下すると、図１に
示すように、圧下後の鋳片は楕円形となり、この鋳片か
らパイプ等を製造する製管工程等で搬送トラブルや管形
状不良等の問題が発生する。Further, when the round slab 13 is reduced, as shown in FIG. 1, the slab after the reduction has an elliptical shape, and there is a transportation trouble or a defective pipe shape in a pipe manufacturing process for manufacturing a pipe or the like from the slab. And other problems occur.
【００１３】したがって、連続鋳造においては、中心偏
析やセンターポロシティを低減するとともに、内部割れ
のない、しかも断面形状が良好な鋳片の製造が求められ
る。本発明の目的は、中心偏析やセンターポロシティを
低減するとともに内部割れを抑制し、さらに、断面形状
の良好な鋳片の製造を可能とする連続鋳造鋳片の製造方
法を提供することにある。[0013] Therefore, in continuous casting, it is required to produce a slab with reduced center segregation and center porosity, no internal cracks, and a good cross-sectional shape. An object of the present invention is to provide a method of manufacturing a continuous cast slab that reduces center segregation and center porosity, suppresses internal cracks, and enables the manufacture of a slab having a good cross-sectional shape.
【００１４】[0014]
【課題を解決するための手段】本発明者らは、上記の課
題を解決するため、丸鋳片用の連続鋳造装置に、未凝固
部を有する凝固完了前の鋳片を圧下する水平ロールを一
対と、完全凝固した鋳片を圧下する垂直および水平ロー
ルを各一対組み込み、種々の実験および検討をおこな
い、鋳片の内部品質および断面形状を調査した。なお、
本明細書において、未凝固部を有する鋳片の圧下を未凝
固圧下、その圧下量を未凝固圧下量ともいい、完全凝固
した鋳片の圧下を、凝固後圧下、その圧下量を凝固後圧
下量ともいう。また、固相率は圧下直前の固相率であ
る。Means for Solving the Problems In order to solve the above-mentioned problems, the inventors of the present invention provided a continuous casting apparatus for round cast slabs with a horizontal roll for rolling down a cast slab having an unsolidified portion before solidification was completed. A pair and a pair of vertical and horizontal rolls for rolling down a completely solidified slab were incorporated, and various experiments and examinations were conducted to investigate the internal quality and cross-sectional shape of the slab. In addition,
In the present specification, the reduction of the slab having an unsolidified portion is the unsolidification reduction, the amount of reduction is also referred to as the unsolidification reduction amount, the reduction of the completely solidified slab is the reduction after solidification, and the reduction amount is the reduction after solidification. Also called quantity. The solid fraction is the solid fraction immediately before the reduction.
【００１５】図２は、センターポロシティおよび中心偏
析に及ぼす固相率０．９９以下の未凝固圧下比（未凝固
圧下量／固相率０．９９以下の未凝固部の厚さ）の影響
を示すグラフである。図３は、内部割れに及ぼす鋳片の
中心部の固相率の影響を示すグラフである。FIG. 2 shows the effect of the unsolidified rolling reduction ratio of the solid phase ratio of 0.99 or less (the unsolidified rolling reduction / the thickness of the unsolidified portion having the solid phase ratio of 0.99 or less) on center porosity and center segregation. It is a graph shown. FIG. 3 is a graph showing the effect of the solid fraction at the center of the slab on internal cracks.
【００１６】図４は、内部割れに及ぼす固相率０．８以
下の未凝固圧下比（未凝固圧下量／固相率０．８以下の
未凝固部の厚さ）の影響を示すグラフである。図２〜４
に示す実験結果および凝固後圧下の実験より、以下の
(a) 〜(d) の知見が得られた。FIG. 4 is a graph showing the effect of the unsolidified rolling reduction ratio of the solid phase ratio of 0.8 or less (unsolidified rolling reduction / thickness of the unsolidified portion having the solid phase ratio of 0.8 or less) on internal cracking. is there. Figures 2-4
From the experimental results shown in and the experiment under pressure after coagulation,
The findings in (a) to (d) were obtained.
【００１７】(a) 固相率０．９９以下の未凝固圧下比が
特定値以上で圧下するとセンターポロシティおよび中心
偏析は著しく改善する。 (b) 鋳片の中心部の固相率（以下、中心部の固相率とも
いう）が０．８より大きい場合には、未凝固圧下による
内部割れの発生はない。(A) When the unsolidification reduction ratio with a solid fraction of 0.99 or less is reduced at a specific value or more, the center porosity and center segregation are remarkably improved. (b) When the solid fraction at the center of the slab (hereinafter, also referred to as the solid fraction at the center) is larger than 0.8, no internal cracking occurs due to unsolidification pressure.
【００１８】(c) 中心部の固相率が０．８以下の場合に
は、固相率０．８以下の未凝固圧下比が特定値以上で圧
下をおこなうと、内部割れが発生しない。 (d) 凝固後圧下により断面形状の良好な鋳片が得られ、
内部割れの発生もない。(C) In the case where the solid fraction at the center is 0.8 or less, the internal crack does not occur if the unsolidified draft ratio at the solid fraction of 0.8 or less is reduced to a specific value or more. (d) A slab having a good cross-sectional shape is obtained by reduction after solidification,
There are no internal cracks.
【００１９】本発明は以上の知見に基づくもので、その
要旨は下記の(1) から(4) のとおりである。 (1) 連続鋳造装置に未凝固部を有する鋳片を圧下する未
凝固圧下装置を設け、固相率が０．９９以下となる未凝
固部厚の０．４倍以上１．２倍以下の圧下量で、かつ、
鋳片の中心部の固相率が０．８以下の時には、固相率が
０．８以下となる未凝固部厚の１．５倍以上の圧下量で
未凝固鋳片を圧下することを特徴とする連続鋳造鋳片の
製造方法。The present invention is based on the above findings, and the gist is as follows (1) to (4). (1) The continuous casting apparatus is provided with an unsolidified rolling device for rolling down a slab having an unsolidified portion, and the solid phase ratio is 0.4 times or more and 1.2 times or less the thickness of the unsolidified portion where the solid phase ratio becomes 0.99 or less. With the amount of reduction, and
When the solid fraction at the center of the slab is 0.8 or less, the unsolidified slab is reduced by a reduction amount of 1.5 times or more the unsolidified portion thickness at which the solid fraction is 0.8 or less. A method for producing continuous cast slabs.
【００２０】(2) 上記未凝固鋳片の中心部の固相率が
０．４〜０．８であることを特徴とする上記(1) 項に記
載の連続鋳造鋳片の製造方法。 (3) 上記未凝固圧下装置が同一面内に２から４個のロー
ルを配置したロール式未凝固圧下装置であることを特徴
とする上記(1) または(2) 項に記載の連続鋳造鋳片の製
造方法。(2) The method for producing a continuous cast slab according to the above item (1), wherein the solid fraction of the central part of the unsolidified slab is 0.4 to 0.8. (3) The continuous cast casting as described in (1) or (2) above, wherein the unsolidified rolling device is a roll-type unsolidified rolling device in which two to four rolls are arranged in the same plane. How to make pieces.
【００２１】(4) 上記未凝固圧下装置の鋳込み方向下流
に凝固後圧下装置を設け、該未凝固圧下装置で圧下され
た鋳片を、凝固完了後、圧下することを特徴とする上記
(1)から(3) 項のいずれかに記載の連続鋳造鋳片の製造
方法。 なお、上記(1) および(2) 項に記載の固相率は圧下直前
の固相率である。(4) A post-solidification drafting device is provided downstream of the unsolidified drafting device in the pouring direction, and the slab pressed down by the unsolidified drafting device is rolled down after solidification is completed.
The method for producing a continuous cast slab according to any one of (1) to (3). The solid phase ratios described in the above items (1) and (2) are solid phase ratios immediately before reduction.
【００２２】[0022]
【発明の実施の形態】図５は、本発明方法を実現する連
続鋳造装置の構成例を示す概略図である。図５に示すよ
うに、浸漬ノズル２１から鋳型２２に注入された溶鋼２
３は、冷却ロール群２４および案内ロール群２５を経て
冷却され凝固シェル２６が形成され、未凝固部２７を有
する鋳片２８となり、未凝固圧下装置２９および凝固後
圧下装置３０を経てピンチロール３１により引き抜かれ
る。FIG. 5 is a schematic view showing an example of the configuration of a continuous casting apparatus for realizing the method of the present invention. As shown in FIG. 5, molten steel 2 injected into mold 22 from immersion nozzle 21
3 is cooled through a cooling roll group 24 and a guide roll group 25 to form a solidified shell 26 and becomes a slab 28 having an unsolidified portion 27, and a pinch roll 31 through an unsolidified rolling device 29 and a post-solidifying rolling device 30. Is pulled out by
【００２３】本発明方法では、上記のような装置構成の
連続鋳造機において、凝固完了前の未凝固部を有する鋳
片２８を未凝固圧下装置２９で圧下する。図６は、本発
明に係る未凝固圧下装置による未凝固圧下を説明する模
式図である。In the method of the present invention, in the continuous casting machine having the above-described apparatus configuration, the slab 28 having an unsolidified portion before solidification is reduced by the unsolidification rolling device 29. FIG. 6 is a schematic diagram for explaining unsolidification reduction by the unsolidification reduction device according to the present invention.
【００２４】同図に示すように、未凝固圧下装置２９
は、未凝固部２７を有する鋳片２８を圧下するロール３
２または図示していない金型を備え、固相率が０．９９
以下となる未凝固部厚Ｍおよび固相率が０．８以下とな
る未凝固部厚Ｎの鋳片２８を圧下する。なお、符号３３
は鋳片縦断面の固相率０．９９の線、３４は固相率０．
８の線である。As shown in FIG.
Is a roll 3 for rolling down a slab 28 having an unsolidified portion 27.
2 or a mold (not shown) with a solid phase ratio of 0.99
The slab 28 having an unsolidified portion thickness M and a solid phase ratio N of 0.8 or less is reduced. Note that reference numeral 33
Is a line having a solid phase ratio of 0.99 in the vertical section of the slab, and 34 is a line having a solid phase ratio of 0.9.
Line 8.
【００２５】ここに、本発明方法によれば、固相率が
０．９９以下となる未凝固部厚Ｍの０．４倍以上１．２
倍以下の圧下量で、かつ、鋳片の中心部の固相率が０．
８以下の時には、固相率が０．８以下となる未凝固部厚
Ｎの１．５倍以上の圧下量で未凝固鋳片を圧下する。Here, according to the method of the present invention, the solid phase ratio is 0.4 times or more and 1.2 times or more the thickness M of the unsolidified portion where the solid fraction is 0.99 or less.
The amount of reduction is not more than twice and the solid phase ratio at the center of the slab is 0.
When it is 8 or less, the unsolidified slab is reduced by a reduction amount of 1.5 times or more of the unsolidified portion thickness N at which the solid fraction is 0.8 or less.
【００２６】次に、圧下量を固相率が０．９９以下とな
る未凝固部の厚さＭの０．４倍以上１．２倍以下とした
理由について説明する。図２に示したように、固相率が
０．９９以下となる未凝固部厚Ｍの０．４倍以上の圧下
量で圧下すると、圧下が内部に浸透し濃化溶鋼が鋳込み
上流側に絞り出されセンターポロシティおよび中心偏析
が著しく改善する。これに対し、圧下量が０．４倍未満
では、圧下の浸透が少なくセンターポロシティおよび中
心偏析の改善が不充分である。また、圧下量が１．２倍
より大きい場合には、センターポロシティおよび中心偏
析は改善するが、圧下力が著しく増大するため、未凝固
圧下装置が大型化し経済的でない。さらに、圧下工具で
あるロールまたは金型が損傷し易くなるという問題もあ
る。Next, the reason why the reduction amount is set to be 0.4 times or more and 1.2 times or less the thickness M of the unsolidified portion where the solid fraction is 0.99 or less will be described. As shown in FIG. 2, when the reduction is performed at a reduction amount of 0.4 times or more of the unsolidified portion thickness M at which the solid fraction is 0.99 or less, the reduction penetrates into the inside, and the concentrated molten steel flows upstream of the casting. The center porosity and center segregation are significantly improved. On the other hand, when the reduction amount is less than 0.4 times, the reduction in the reduction is small, and the improvement of the center porosity and the center segregation is insufficient. When the rolling reduction is more than 1.2 times, the center porosity and the center segregation are improved, but the rolling force is remarkably increased. Further, there is a problem that a roll or a mold as a pressing tool is easily damaged.
【００２７】次に、鋳片の中心部の固相率が０．８以下
の時には、圧下量を未凝固部厚Ｎの１．５倍以上とした
理由について説明する。図３に示したように、中心部の
固相率が０．８以下の鋳片を圧下すると凝固界面に引張
り力が作用し内部割れが発生する。しかし、図４に示す
ように、固相率が０．８以下となる未凝固部厚Ｎの１．
５倍以上の圧下量で圧下する場合には、凝固界面は圧縮
応力状態となり、また溶鋼流動が大きくなるため凝固界
面近傍の樹枝状晶間に吸引された濃化溶鋼も鋳込み上流
側に絞り出され内部割れの発生は大幅に抑制される。中
心部の固相率が０．８以下の時、圧下量がＮの１．５倍
未満では、内部割れの抑制が不充分である。Next, the reason why the reduction amount is 1.5 times or more the thickness N of the unsolidified portion when the solid fraction at the center of the slab is 0.8 or less will be described. As shown in FIG. 3, when a slab having a solid fraction of 0.8 or less at the center is rolled down, a tensile force acts on the solidification interface to cause internal cracks. However, as shown in FIG. 4, the unsolidified portion thickness N of 1.
When the rolling reduction is more than 5 times, the solidification interface is in the state of compressive stress, and the flow of molten steel increases, so the concentrated molten steel sucked between dendrites near the solidification interface is also squeezed out to the upstream side of casting. As a result, the occurrence of internal cracks is greatly suppressed. When the solid fraction at the center is 0.8 or less, if the amount of reduction is less than 1.5 times N, the suppression of internal cracking is insufficient.
【００２８】好ましくは、Ｍの０．６倍以上１．０倍以
下の圧下量で、かつ、中心部の固相率が０．８以下の時
には、Ｎの１．６倍以上の圧下量である。なお、未凝固
圧下装置を鋳込み方向に複数段設ける場合には、少なく
ともその最終段の未凝固圧下装置で上記の圧下をおこな
えばよい。Preferably, when the reduction amount is 0.6 times or more and 1.0 times or less of M, and when the solid phase ratio at the center is 0.8 or less, the reduction amount is 1.6 times or more of N. is there. When a plurality of unsolidified rolling devices are provided in the casting direction, the above-described reduction may be performed by at least the last unsolidified rolling device.
【００２９】次に、本発明の好適態様として、未凝固圧
下をおこなうときの未凝固鋳片の中心部の固相率が０．
４〜０．８であるとした理由を説明する。中心部の固相
率が０．８を越えると、鋳片の変形抵抗が増加するた
め、大きな圧下力が必要となり、未凝固圧下装置が大型
化し、設備費が高くなる。Next, as a preferred embodiment of the present invention, the solid phase ratio at the center of the unsolidified slab when the unsolidifying reduction is performed is set to 0.1%.
The reason why the value is 4 to 0.8 will be described. If the solid phase ratio at the center exceeds 0.8, the deformation resistance of the slab increases, so a large rolling force is required, and the size of the unsolidified rolling device is increased, and the equipment cost is increased.
【００３０】中心部の固相率が０．４未満では、内部割
れの発生を防止するに必要な未凝固圧下量が大きくなる
ため、圧下による断面減少が大きく、連続鋳造の生産性
が著しく減少する。また、丸鋳片などの場合、圧下に伴
う断面形状の変化が大きく、後述する凝固後圧下による
断面形状の修正が難しくなり、形状不良が発生しやす
い。好ましくは、中心部の固相率は０．６〜０．８の範
囲である。If the solid phase ratio at the center is less than 0.4, the unsolidified rolling reduction required to prevent the occurrence of internal cracks becomes large, so that the reduction in cross-section due to rolling is large and the productivity of continuous casting is significantly reduced. I do. Further, in the case of a round slab or the like, a change in the cross-sectional shape due to the reduction is large, and it is difficult to correct the cross-sectional shape by the post-solidification reduction described later, and a defective shape is likely to occur. Preferably, the solid fraction at the center is in the range of 0.6 to 0.8.
【００３１】次に、本発明の好適態様である同一面内に
２〜４個のロールを配置したロール式未凝固圧下装置に
よる圧下について、４ロール式未凝固圧下装置の場合を
例に説明する。Next, a preferred embodiment of the present invention, in which two or four rolls are arranged in the same plane and a roll-type unsolidification rolling device, will be described with reference to a 4-roll type non-solidification rolling device as an example. .
【００３２】未凝固圧下は鋳片の移動に同期しておこな
うことが必要であり、金型による圧下の場合には、金型
を組み込んだ圧下装置を鋳片に同期して鋳込み方向に走
行制御する機構とそのための高度な速度制御技術が必要
となる。一方、ロールによる圧下では、上記の機構が不
要であり、さらに、高度な速度制御も必要としないた
め、安価な設備で安定した鋳造が可能となる。It is necessary to perform unsolidification reduction in synchronization with the movement of the slab. In the case of reduction by a die, a reduction device incorporating the die is controlled in running in the casting direction in synchronization with the slab. And a sophisticated speed control technology for that. On the other hand, under rolling by a roll, the above mechanism is unnecessary, and furthermore, high speed control is not required, so that stable casting can be performed with inexpensive equipment.
【００３３】図７は、４ロール式未凝固圧下装置での圧
下を説明する模式図である。同図に示すように、４ロー
ル式未凝固圧下装置３５は、同一面内に一対の孔型ロー
ル３６と、これに直角に配置した一対の孔型ロール３７
を有しており、孔型ロール３６、３７の一方、または両
方のロールで未凝固部３８を有する鋳片３９を圧下す
る。未凝固圧下量は、少なくともどちらか一方のロール
対の圧下量が前記の条件を満足するように設定される。
同図には、ロールが孔型形状である場合を示したが、フ
ラット形状のロールを用いても良い。FIG. 7 is a schematic diagram for explaining the reduction in a four-roll unsolidified reduction device. As shown in the figure, the four-roll unsolidification rolling device 35 includes a pair of grooved rolls 36 in the same plane and a pair of grooved rolls 37 arranged at right angles thereto.
The cast slab 39 having the unsolidified portion 38 is reduced by one or both of the grooved rolls 36 and 37. The unsolidified rolling reduction is set so that the rolling reduction of at least one of the roll pairs satisfies the above-described condition.
Although FIG. 2 shows a case where the roll has a hole shape, a flat roll may be used.
【００３４】なお、上記で「同一面内」とは、各ロール
と鋳片とで形成される接触域が少なくとも部分的に重な
る状態にすることであり、ロール軸を傾斜させたり、ロ
ールを鋳込み方向にずらせたりすることも含む。In the above, "in the same plane" means that the contact area formed by each roll and the cast piece at least partially overlaps, and the roll axis is inclined or the roll is cast. It also includes shifting in the direction.
【００３５】次に、本発明の好適態様として、未凝固圧
下装置の鋳込み方向下流に凝固後圧下装置を設け未凝固
圧下した鋳片を凝固完了後に圧下するとした理由を説明
する。Next, as a preferred embodiment of the present invention, the reason why a post-solidification rolling device is provided downstream of the unsolidification rolling device in the casting direction and the unsolidified rolling slab is lowered after solidification is completed will be described.
【００３６】図５に示すように、未凝固圧下装置２９と
ピンチロール３１との間に、未凝固圧下し凝固完了した
鋳片を圧下するロールまたは金型を備えた凝固後圧下装
置３０を設ける。As shown in FIG. 5, between the unsolidified rolling device 29 and the pinch roll 31, a post-solidifying rolling device 30 provided with a roll or a mold for rolling the unsolidified rolling and the solidified slab is provided. .
【００３７】ところで、未凝固圧下においては、上述し
たように鋳片の内部品質確保の観点から未凝固圧下量が
制約されるため、未凝固圧下後の鋳片は断面形状が不良
となり易く寸法精度の確保が難しい。In the unsolidified rolling, the unsolidified rolling amount is restricted from the viewpoint of ensuring the internal quality of the slab as described above. Is difficult to secure.
【００３８】凝固後圧下装置３０による圧下では、鋳片
の内部品質確保の観点からの圧下量の制約がないため、
寸法精度の確保の観点から適正な圧下量を選択すること
ができ、未凝固圧下した鋳片の断面形状を整え、寸法精
度の高い鋳片に成形することが可能となる。さらに、必
要に応じ、その圧下量を調整して製管工程等に供給する
数種類の寸法の鋳片を作り分けることができる。In the reduction by the reduction device 30 after solidification, there is no restriction on the reduction amount from the viewpoint of ensuring the internal quality of the slab.
From the viewpoint of ensuring dimensional accuracy, an appropriate amount of reduction can be selected, and the cross-sectional shape of the unsolidified and reduced slab can be adjusted to form a slab with high dimensional accuracy. Further, if necessary, the slabs of several kinds of dimensions to be supplied to the pipe making process or the like by adjusting the amount of reduction thereof can be separately formed.
【００３９】図５に示すように、通常、凝固後圧下装置
３０は、垂直圧下装置３０ａと水平圧下装置３０ｂを交
互に複数段設けるが、１段であっても良い。また、丸鋳
片等の製造の場合には、同一面内に３個以上のロールま
たは金型を配置した凝固後圧下装置を１段設けても良
い。As shown in FIG. 5, usually, the post-solidification pressing device 30 is provided with a plurality of vertical pressing devices 30a and horizontal pressing devices 30b alternately. In the case of manufacturing round cast slabs or the like, a one-stage post-solidification rolling device in which three or more rolls or dies are arranged in the same plane may be provided.
【００４０】また、未凝固圧下装置の上流に電磁攪拌装
置を設け、未凝固圧下前の鋳片の組織を等軸晶化するこ
とにより、鋳片品質をさらに改善することが出来る。Further, the quality of the slab can be further improved by providing an electromagnetic stirrer upstream of the unsolidifying rolling device and making the structure of the slab before the unsolidifying rolling equiaxed.
【００４１】[0041]
（実施例１）図５に示す基本構成で、表１に示す設備仕
様の丸鋳片用連続鋳造装置を使用し、直径２５０ｍｍの
鋳型で高炭素鋼（Ｃ：１．０重量％）を鋳造し、未凝固
圧下および凝固後圧下をおこない直径１９０ｍｍの鋳片
を製造した。(Example 1) High-carbon steel (C: 1.0% by weight) was cast with a 250 mm diameter mold using a continuous casting device for round cast slabs having the basic configuration shown in FIG. Then, unsolidification reduction and reduction after solidification were performed to produce a slab having a diameter of 190 mm.
【００４２】[0042]
【表１】 [Table 1]
【００４３】表２に鋳造条件を示す。なお、未凝固圧下
装置の直前で所定の未凝固部厚となるように、鋳造速度
を１．７〜２．３ｍ／分の間で調整した。また、未凝固
部厚の測定は、鋳片温度解析ならびにＦｅ−Ｓ添加によ
る凝固厚測定等によりおこなった。Table 2 shows the casting conditions. In addition, the casting speed was adjusted between 1.7 and 2.3 m / min so that a predetermined unsolidified portion thickness was obtained immediately before the unsolidification rolling device. In addition, the measurement of the unsolidified portion thickness was performed by a slab temperature analysis, a solidified thickness measurement by adding Fe-S, and the like.
【００４４】[0044]
【表２】 [Table 2]
【００４５】定常鋳造部より、鋳込み方向に１００ｍｍ
の間隔で２１個の横断面サンプルを採取し、内部割れ、
中心偏析、センターポロシティおよび真円度を調査し
た。内部割れは、横断面のサルファプリントをおこな
い、割れ長さで評価した。中心偏析は、横断面サンプル
の中心部のＣ濃度を分析し、それを横断面の平均濃度Ｃ
0との比、すなわち偏析度（Ｃ／Ｃ0 ）として整理し
た。センターポロシティは、横断面サンプル内のセンタ
ーポロシティの総面積を測定し、鋳片断面積との比でセ
ンターポロシティ面積率として表した。真円度は、横断
面サンプルの最大径と最小径の差を平均径で除した値を
真円偏差率と定義し評価した。表３に、上記の品質調査
結果を示す。なお、同表の値は、２１個の横断面サンプ
ルの平均値である。100 mm in the casting direction from the steady casting part
21 cross-sectional samples were taken at intervals of
Center segregation, center porosity and roundness were investigated. The internal cracks were evaluated by the length of the cracks by sulfur printing of the cross section. Center segregation analyzes the C concentration at the center of a cross-sectional sample and calculates the average C concentration of the cross-section.
It was arranged as a ratio to 0 , that is, the degree of segregation (C / C 0 ). The center porosity was obtained by measuring the total area of the center porosity in the cross-sectional sample, and expressed as a center porosity area ratio by a ratio to the slab cross-sectional area. The roundness was evaluated by defining the value obtained by dividing the difference between the maximum diameter and the minimum diameter of the cross-sectional sample by the average diameter as the roundness deviation rate. Table 3 shows the results of the quality survey. The values in the table are average values of 21 cross-sectional samples.
【００４６】[0046]
【表３】 [Table 3]
【００４７】本発明例は、センターポロシティ面積率お
よび偏析度が小さく良好であり、内部割れも無しまたは
軽微であり問題なかった。さらに、凝固後圧下をおこな
った本発明例２〜６は、真円偏差率も良好であり、製管
工程からの要求である真円偏差率３％以内を達成した。In the examples of the present invention, the center porosity area ratio and the degree of segregation were small and good, and there was no problem with no or slight internal cracks. In addition, in Invention Examples 2 to 6 in which the reduction after solidification was performed, the roundness deviation rate was good, and the roundness deviation rate required from the pipe making process was within 3%.
【００４８】一方、比較例１は、センターポロシティお
よび中心偏析は良好であったが、内部割れが大きく、ま
た、比較例２は、内部割れの発生は無いが、センターポ
ロシティ面積率および偏析度が大きく不良であった。On the other hand, Comparative Example 1 had good center porosity and center segregation, but had large internal cracks. Comparative Example 2 had no internal cracks, but had a low center porosity area ratio and degree of segregation. It was big bad.
【００４９】[0049]
【発明の効果】本発明により、内部割れ、センターポロ
シティおよび中心偏析が少なく断面形状が良好な鋳片の
製造が可能となる。According to the present invention, it is possible to produce a slab having a good sectional shape with little internal cracks, center porosity and center segregation.
【図１】従来法で丸鋳片を圧下した場合の内部割れの発
生を示す模式図である。FIG. 1 is a schematic view showing the occurrence of internal cracks when a round slab is reduced by a conventional method.
【図２】センターポロシティおよび中心偏析に及ぼす固
相率０．９９以下の未凝固圧下比（未凝固圧下量／固相
率０．９９以下の未凝固部の厚さ）の影響を示すグラフ
である。FIG. 2 is a graph showing the effect of the unsolidified rolling ratio at a solid phase ratio of 0.99 or less (the amount of unsolidified rolling reduction / the thickness of an unsolidified portion having a solid phase ratio of 0.99 or less) on center porosity and center segregation. is there.
【図３】内部割れに及ぼす中心部の固相率の影響を示す
グラフである。FIG. 3 is a graph showing the effect of the solid fraction at the center on internal cracks.
【図４】内部割れに及ぼす固相率０．８以下の未凝固圧
下比（未凝固圧下量／固相率０．８以下の未凝固部の厚
さ）の影響を示すグラフである。FIG. 4 is a graph showing the effect of an unsolidified rolling reduction ratio of a solid phase ratio of 0.8 or less (unsolidified rolling reduction / thickness of an unsolidified portion having a solid phase ratio of 0.8 or less) on internal cracking.
【図５】本発明方法を実現する連続鋳造装置の構成例を
示す概略図である。FIG. 5 is a schematic view showing a configuration example of a continuous casting apparatus for realizing the method of the present invention.
【図６】本発明に係る未凝固圧下装置による未凝固圧下
を説明する模式図である。FIG. 6 is a schematic diagram for explaining unsolidification reduction by the unsolidification reduction device according to the present invention.
【図７】４ロール式未凝固圧下装置での圧下を説明する
模式図である。FIG. 7 is a schematic diagram for explaining the reduction in a four-roll unsolidified reduction device.
１１、３２ ロール １２、２７、３８ 未凝固部 １３ 丸鋳片 １４ 凝固界面 １５ 内部割れ ２１ 浸漬ノズル ２２ 鋳型 ２３ 溶鋼 ２４ 冷却ロール群 ２５ 案内ロール群 ２６ 凝固シェル ２８、３９ 鋳片 ２９ 未凝固圧下装置 ３０ 凝固後圧下装置 ３０ａ 垂直圧下装置 ３０ｂ 水平圧下装置 ３１ ピンチロール ３３ 鋳片縦断面の固相率０．９９の線 ３４ 鋳片縦断面の固相率０．８の線 ３５ ４ロール式未凝固圧下装置 ３６ 孔型ロール ３７ 孔型ロール７２に直角に配置した孔型ロール Ｍ 固相率が０．９９以下の未凝固部厚 Ｎ 固相率０．８以下の未凝固部厚 11, 32 Roll 12, 27, 38 Unsolidified part 13 Round cast piece 14 Solidified interface 15 Internal crack 21 Immersion nozzle 22 Mold 23 Molten steel 24 Cooling roll group 25 Guide roll group 26 Solidified shell 28, 39 Cast piece 29 Unsolidified rolling device Reference Signs List 30 Post-solidification drafting device 30a Vertical drafting device 30b Horizontal drafting device 31 Pinch roll 33 Line of solid phase ratio 0.99 in slab vertical section 34 Line of solid phase ratio 0.8 in slab vertical section 35 Four-roll unsolidified Roll-down device 36 Perforated roll 37 Perforated roll arranged at right angles to perforated roll 72 M Non-solidified portion thickness with solid phase ratio of 0.99 or less N Non-solidified portion thickness with solid phase ratio of 0.8 or less
Claims (4)
圧下する未凝固圧下装置を設け、固相率が０．９９以下
となる未凝固部厚の０．４倍以上１．２倍以下の圧下量
で、かつ、鋳片の中心部の固相率が０．８以下の時に
は、固相率が０．８以下となる未凝固部厚の１．５倍以
上の圧下量で未凝固鋳片を圧下することを特徴とする連
続鋳造鋳片の製造方法。An unsolidified rolling device for rolling a slab having an unsolidified portion is provided in a continuous casting device, wherein the thickness of the unsolidified portion is 0.4 times or more and 1.2 times the thickness of the unsolidified portion where the solid phase ratio is 0.99 or less. When the solidification ratio at the center of the slab is 0.8 or less, the reduction amount is 1.5 times or more the thickness of the unsolidified portion where the solidification ratio is 0.8 or less. A method for producing a continuous cast slab, comprising reducing a solidified slab.
４〜０．８であることを特徴とする請求項１に記載の連
続鋳造鋳片の製造方法。2. The method according to claim 1, wherein the unsolidified slab has a solid fraction of 0.
The method for producing a continuous cast slab according to claim 1, wherein the ratio is from 4 to 0.8.
４個のロールを配置したロール式未凝固圧下装置である
ことを特徴とする請求項１または２に記載の連続鋳造鋳
片の製造方法。3. The continuous cast slab according to claim 1, wherein the unsolidified rolling device is a roll-type unsolidified rolling device in which two to four rolls are arranged in the same plane. Production method.
凝固後圧下装置を設け、該未凝固圧下装置で圧下された
鋳片を、凝固完了後、圧下することを特徴とする請求項
１から３のいずれかに記載の連続鋳造鋳片の製造方法。4. A post-solidification drafting device is provided downstream of the unsolidified drafting device in the casting direction, and the slab reduced by the unsolidified drafting device is reduced after solidification is completed. 3. The method for producing a continuously cast slab according to any one of the above items 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29573897A JP3240978B2 (en) | 1997-10-28 | 1997-10-28 | Manufacturing method of continuous cast slab |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29573897A JP3240978B2 (en) | 1997-10-28 | 1997-10-28 | Manufacturing method of continuous cast slab |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11129060A true JPH11129060A (en) | 1999-05-18 |
| JP3240978B2 JP3240978B2 (en) | 2001-12-25 |
Family
ID=17824538
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29573897A Expired - Fee Related JP3240978B2 (en) | 1997-10-28 | 1997-10-28 | Manufacturing method of continuous cast slab |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3240978B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000153342A (en) * | 1998-11-17 | 2000-06-06 | Sumitomo Metal Ind Ltd | Method for continuously casting beam blank |
| JP2013252542A (en) * | 2012-06-07 | 2013-12-19 | Nippon Steel & Sumitomo Metal Corp | Method for continuously casting cast slab |
| CN107116192A (en) * | 2017-06-27 | 2017-09-01 | 中冶京诚工程技术有限公司 | Continuous casting billet screwdown device |
-
1997
- 1997-10-28 JP JP29573897A patent/JP3240978B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000153342A (en) * | 1998-11-17 | 2000-06-06 | Sumitomo Metal Ind Ltd | Method for continuously casting beam blank |
| JP2013252542A (en) * | 2012-06-07 | 2013-12-19 | Nippon Steel & Sumitomo Metal Corp | Method for continuously casting cast slab |
| CN107116192A (en) * | 2017-06-27 | 2017-09-01 | 中冶京诚工程技术有限公司 | Continuous casting billet screwdown device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3240978B2 (en) | 2001-12-25 |
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