JP4005841B2 - Production apparatus and production method of alloyed hot-dip galvanized steel sheet - Google Patents

Production apparatus and production method of alloyed hot-dip galvanized steel sheet Download PDF

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JP4005841B2
JP4005841B2 JP2002142491A JP2002142491A JP4005841B2 JP 4005841 B2 JP4005841 B2 JP 4005841B2 JP 2002142491 A JP2002142491 A JP 2002142491A JP 2002142491 A JP2002142491 A JP 2002142491A JP 4005841 B2 JP4005841 B2 JP 4005841B2
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steel sheet
temperature
hot
temperature difference
furnace
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JP2003328097A (en
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雅次 相場
修宏 鈴村
俊直 水口
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Nippon Steel Corp
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Nippon Steel Corp
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Description

【0001】
【発明の属する技術分野】
本発明は、冷間圧延を行った鋼板表面に溶融亜鉛めっきを施した後に合金化処理を行う合金化溶融亜鉛めっき鋼板の製造装置および製造方法に関する。
【0002】
【従来の技術】
図3は、従来の合金化溶融亜鉛めっき鋼板の製造プロセスを示す図である。
図3の横軸は、時間(秒)を示し、縦軸は、板温(℃)を示す。
冷間圧延後、焼鈍された鋼板は、冷却帯にてN2ガスなどの不活性ガスを吹き付けられて、500℃以下に冷却された後、溶融めっき装置にて表面に亜鉛めっきが施された後、燃焼ガスを用いたガス加熱装置により、ゆっくりと加熱されて合金化処理がなされる。
ここに、合金化処理とは、溶融亜鉛めっきされた鋼板表面を再度加熱して焼付けることにより、母材中のFeとめっき中のZnとの合金化反応を起こさせる処理をいう。
【0003】
しかし、この従来の合金化溶融亜鉛めっき鋼板の製造装置および製造方法には以下のような問題点があった。
1)冷却帯において鋼板が冷却される際に、図3の点線で示すように鋼板両側のエッジ部の温度が鋼板の中央部の温度に比べて低くなり、この温度差が大きい状態で、合金化処理がなされると、合金化むらが発生して表面品質が劣るという問題があった。
【0004】
2)板厚が厚い鋼板から薄い鋼板に変更される際に、溶接部の後段の鋼板は薄いため冷却されやすいので、図3の点線で示すようにこの部分の温度が溶接部前段の鋼板に比べて低くなり、この温度差は縮まらない状態で、合金化処理がなされると、溶接点の後段における鋼板の合金化不良が生じ歩留まり落ちが発生するという問題があった。
3)特に合金化処理設備として誘導加熱を行うなどして急速加熱によりライン長を短くする場合、急速な温度変化によって、前記の鋼板エッジ部や溶接部と鋼板の中央部との温度差の影響が大きくなって、前述のめっき表面の合金化むらが顕著になるという問題点があった。
【0005】
なお、本発明に類似の先行技術を開示する文献として、特開昭56−51531号公報には、以下のような技術が開示されている。
この先行技術は、70℃以上の冷却速度にてロール冷却した後、300〜500℃の温度範囲に10秒以上保持した後に亜鉛めっきする溶融亜鉛めっき鋼板の製造方法である。
しかし、特開昭56−51531号公報は溶融亜鉛めっき鋼板の製造法について開示されているが、その後、再加熱して合金化処理を施す点、および、合金化処理に際して鋼板の幅方向および長手方向の温度差により鋼板表面に合金化むらが発生するという問題点およびその解決手段について全く開示されていない。
【0006】
【発明が解決しようとする課題】
本発明は、前記のような従来技術の問題点を解決し、急速加熱によるコンパクトな合金化処理設備を用いても、鋼板表面に合金化むらが発生しない合金化溶融亜鉛めっき鋼板の製造装置および製造方法を提供することを課題とする。
【0007】
【課題を解決するための手段】
本発明は、前述の課題を解決するために、均熱炉と合金化炉を組み合わせた装置を用いて、均熱炉により特定の条件にて均熱処理を行った鋼板表面に溶融亜鉛めっきを施し、誘導加熱装置にて急速加熱して合金化処理を行うことにより、板幅方向および長手方向の板温の相違による鋼板表面の合金化むらをなくすことができる合金化溶融亜鉛めっき鋼板の製造装置および製造方法を提供するものであり、その要旨とするところは、特許請求の範囲に記載した通りの下記内容である。
【0008】
(1)冷間圧延された鋼板の表面に溶融亜鉛めっきを施した後、150mpmの通板速度における鋼板の昇温速度が52.1〜125.0℃/秒で加熱でき、高さが3.0m以内の誘導加熱装置を有する合金化炉により合金化処理を行う合金化溶融亜鉛めっき鋼板の製造装置であって、スナウトの前段に、鋼板の板温を300℃〜500℃の範囲で20秒以上均温保持し均熱炉出側で鋼板の幅方向の温度差および溶接点での長手方向の温度差を5℃以下にする均熱炉を有することを特徴とする合金化溶融亜鉛めっき鋼板の製造装置。
(2)冷間圧延された鋼板の表面に溶融亜鉛めっきを施した後、150mpmの通板速度における鋼板の昇温速度が52.1〜125.0℃/秒で加熱でき、高さが3.0m以内の誘導加熱装置を有する合金化炉により合金化処理を行う合金化溶融亜鉛めっき鋼板の製造方法であって、スナウトの前段に設けた均熱炉内で鋼板の板温を300℃〜500℃の範囲で20秒以上均温保持し均熱炉出側で鋼板の幅方向の温度差および溶接点での長手方向の温度差を5℃以下にすることを特徴とする合金化溶融亜鉛めっき鋼板の製造方法。
【0009】
【発明の実施の形態】
本発明における合金化溶融亜鉛めっき鋼板の製造方法の実施形態を、図1および図2、図4および図5を用いて説明する。
図1は、本発明におけるの合金化溶融亜鉛めっき鋼板の製造装置の実施形態を示す図である。
図1において、冷間圧延された鋼板は焼鈍されロール冷却装置1により70℃/秒以上の冷却速度で冷却された後、均熱炉2にて20秒以上、等温保持された後、スナウト3を通じて溶融亜鉛めっきポット4にて鋼板表面に溶融亜鉛めっきが施される。
冷却装置をロール冷却装置としたが、ガス冷却においてもその効果は同等である。
溶融亜鉛めっきが施された鋼板は、めっき付着量制御装置5により適正な目付け量とした後、高さ3.0m以下の誘導加熱装置6、保定炉7により合金化処理がなされ、鋼板上昇路8および鋼板下降路9を介して水冷槽10にて常温まで冷却される。
【0010】
図2は、本発明におけるの合金化溶融亜鉛めっき鋼板の製造方法の実施形態を示す図である。
図2において、横軸は時間(秒)を示し、縦軸は板温(℃)を示す。
冷間圧延後、焼鈍された鋼板は、500℃以下の温度まで冷却され、均熱炉によりその温度にて20秒以上保持される。冷却されることにより、図2の点線で示した鋼板のエッジ部または厚さの薄い溶接部の温度は、鋼板の中央部の温度より15℃程度低くなるが、この温度差は均熱炉にて300〜500℃にて20秒以上保持されることによりほとんどなくなっている。
ここに、300〜500℃としたのは、この温度範囲が溶融めっきを施すのに好ましい温度範囲だからである。
【0011】
その後、溶融めっき装置にて鋼板表面に亜鉛めっきが施される際に、この温度差は多少広がるが、均熱炉出側(溶融めっき装置入側)にて、この温度差が
5℃以内になっているため、溶融亜鉛めっき後に、誘導加熱装置を用いて昇温速度が10〜150℃/secの範囲で急速に加熱しても、前記温度差はさほど問題にならない。
その結果、鋼板のエッジ部や板厚の薄い部分の溶接部であっても鋼板表面の合金化が均一に進むので、鋼板表面の合金化むらの発生を防止することできる。
【0012】
図4は、均熱炉の炉内における鋼板の中央部とエッジ部の板温の変化を例示する図である。
均熱炉の入り側における、鋼板の中央部とエッジ部の温度差は15℃であるが、均熱炉出側(11パス)における温度差は5℃に縮まっている。
図5は、均熱炉の前後における、鋼帯の長手方向の温度変化を示す図である。図5の右側が板厚の厚い(1.0mm)の鋼板の板温を示しており、左側は板厚の薄い(0.8mm)の鋼板の板温を示しており、その境界部分が溶接点を示している。
【0013】
図5からわかるように、従来の溶融めっき装置入側、および、本発明の均熱炉入側の板温は溶接点の前後で、約20℃の温度差が認められるが、本発明のめっき装置入側(均熱炉の出側)の板温は、溶接点の前後で約5℃に縮まっている。
【0014】
【実施例】
表1に、本発明における合金化溶融亜鉛めっき鋼板の製造方法の実施例を示す。
板厚0.8mm、板幅1250mmの鋼板を、冷却帯にて冷却し、均熱炉にて20秒以上均温保持した後、溶融めっきを施し、誘導加熱装置にて加熱速度が10〜150℃の範囲で加熱して合金化処理を行った。
【表1】

Figure 0004005841
NO.1〜NO.4は、ラインスピード30mpmにて、焼鈍炉を出てから均熱炉に入るまでの冷却をN2ガスを用いたガス冷却を行った場合を示している。ラインスピードが遅いので、均熱炉および誘導加熱装置における在炉時間が他の実施例に比べて長くなっているため、板幅方向および長手方向の温度差が比較的小さく抑えられることから合金化層の評価は◎であり、鋼板表面の合金化むらは全く認められなかった。
【0015】
NO.5〜NO.8は、ラインスピード150mpmにて、焼鈍炉を出てから均熱炉に入るまでの冷却をロール冷却法を用いて冷却速度70℃/sec以上の急速冷却を行った場合を示している。ラインスピードが速いので、均熱炉および誘導加熱装置における在炉時間は短いが、均熱炉により、板幅方向および長手方向の温度差がある程度低減できることから合金化層の評価は○であり、鋼板表面の合金化むらはほとんど認められなかった。
【0016】
NO.9は比較例であり、ラインスピード30mpmにて、ガス冷却を用いてゆっくりと冷却を行った場合を示している。ラインスピードが遅いので、誘導加熱装置における在炉時間は比較的長いが、均熱炉により均熱を行っていないので、板幅方向および長手方向の温度差が縮まっていないことから合金化層の評価は△であり、鋼板表面に合金化むらが認められた。
NO.10は比較例であり、ラインスピード150mpmにて、ロール冷却を用いて70℃/sec以上の急速冷却を行った場合を示している。ラインスピードが速いので、誘導加熱装置における在炉時間が短いうえ、均熱炉により均熱を行っていないので、板幅方向および長手方向の温度差が大きいことから合金化層の評価は×であり、鋼板表面に合金化むらが顕著に認められた。
【0017】
【発明の効果】
本発明によれば、ロール冷却や誘導加熱のように急速冷却および/または急速加熱を施しても、鋼板表面に合金化むらが発生しない合金化溶融亜鉛めっき鋼板の製造装置および製造方法を提供することでき、具体的には、以下のような産業上有用な著しい効果を奏する。
【0018】
1)冷却帯および溶融めっき装置において鋼板が冷却される際に、図3に示すように均熱炉にて20秒以上均温保持することにより鋼板中央部と両側のエッジ部の温度差を5℃程度まで縮めることができるので、急速加熱によるコンパクトな合金化処理設備を用いても、合金化処理しためっき表面に合金化むらの発生を防止することができる。
2)板厚が厚い鋼板から薄い鋼板に変更される際に、溶接部の後段の鋼板は薄いため冷却されやすいが、図4に示すように溶接点前後の鋼板温度の差を5℃程度に抑えることができるので、ロール冷却やガス冷却によって急速冷却しても、合金化処理しためっき表面に合金化むらの発生を防止することができる。
3)ロール冷却や誘導加熱装置によって急速冷却および/または急速加熱を行うことにより、ラインスピードを速く設定することができ、目標の生産量を確保しつつ設備全体のライン長を短くるすことができるので、設備コストを著しく低減することができる。
【図面の簡単な説明】
【図1】 本発明におけるの合金化溶融亜鉛めっき鋼板の製造装置の実施形態を示す図である。
本発明の
【図2】 本発明におけるの合金化溶融亜鉛めっき鋼板の製造方法の実施形態を示す図である。
【図3】 従来の合金化溶融亜鉛めっき鋼板の製造方法示す図である。
【図4】 均熱炉の炉内における鋼板の中央部とエッジ部の板温の変化を例示する図である。
【図5】 均熱炉の前後における、鋼帯の長手方向の温度変化を示す図である。
【符号の説明】
1:ロール冷却装置、
2:均熱炉、
3:スナウト、
4:溶融亜鉛めっきポット、
5:めっき付着量制御装置、
6:誘導加熱装置、
7:保定炉、
8:鋼板上昇路、
9:鋼板下降路、
10:水冷槽[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and a method for producing an alloyed hot-dip galvanized steel sheet that is subjected to alloying treatment after hot-dip galvanizing is performed on the surface of a cold-rolled steel sheet.
[0002]
[Prior art]
FIG. 3 is a view showing a manufacturing process of a conventional galvannealed steel sheet.
The horizontal axis in FIG. 3 indicates time (seconds), and the vertical axis indicates the plate temperature (° C.).
After cold rolling, the annealed steel sheet is blown with an inert gas such as N2 gas in a cooling zone, cooled to 500 ° C. or lower, and then galvanized on the surface by a hot dipping apparatus. Then, it is slowly heated by a gas heating device using combustion gas to be alloyed.
Here, the alloying treatment refers to a treatment for causing an alloying reaction between Fe in the base material and Zn in the plating by reheating and baking the surface of the hot-dip galvanized steel sheet.
[0003]
However, this conventional alloyed hot-dip galvanized steel sheet manufacturing apparatus and manufacturing method have the following problems.
1) When the steel sheet is cooled in the cooling zone, the temperature of the edge part on both sides of the steel sheet becomes lower than the temperature of the central part of the steel sheet as shown by the dotted line in FIG. When the alloying treatment is performed, there is a problem that unevenness of alloying occurs and the surface quality is inferior.
[0004]
2) When the steel plate is changed from a thick steel plate to a thin steel plate, the steel plate in the latter part of the welded part is thin and easy to cool, so the temperature of this part changes to the steel plate in the former part of the welded part as shown by the dotted line in FIG. If the alloying process is performed in a state where the temperature difference is not reduced and the temperature difference is not reduced, there is a problem that the alloying failure of the steel sheet at the later stage of the welding point occurs and the yield is reduced.
3) Especially when the line length is shortened by rapid heating, such as by induction heating as an alloying equipment, the effect of the temperature difference between the steel plate edge or weld and the center of the steel plate due to rapid temperature changes. There is a problem that the above-mentioned unevenness of alloying on the plating surface becomes remarkable.
[0005]
As a document disclosing the prior art similar to the present invention, Japanese Patent Laid-Open No. 56-51531 discloses the following technique.
This prior art is a method for producing a hot-dip galvanized steel sheet that is roll-cooled at a cooling rate of 70 ° C. or higher and then galvanized after being held in a temperature range of 300 to 500 ° C. for 10 seconds or longer.
However, Japanese Patent Laid-Open No. 56-51531 discloses a method for producing a hot dip galvanized steel sheet, but after that, it is reheated for alloying treatment, and the width direction and longitudinal direction of the steel sheet during alloying treatment. There is no disclosure of the problem that unevenness of alloying occurs on the surface of the steel sheet due to the temperature difference in the direction and the means for solving it.
[0006]
[Problems to be solved by the invention]
The present invention solves the problems of the prior art as described above, and an apparatus for producing an alloyed hot-dip galvanized steel sheet that does not cause uneven alloying on the steel sheet surface even when a compact alloying treatment facility by rapid heating is used, and It is an object to provide a manufacturing method.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention performs hot dip galvanization on the surface of a steel sheet that has been soaked under a specific condition in a soaking furnace, using an apparatus that combines a soaking furnace and an alloying furnace. An alloyed hot-dip galvanized steel sheet manufacturing apparatus that eliminates uneven alloying of the steel sheet surface due to differences in sheet temperature in the sheet width direction and the longitudinal direction by rapid heating with an induction heating device And a manufacturing method, the gist of which is as described in the claims below.
[0008]
(1) After hot-dip galvanizing on the surface of the cold-rolled steel sheet, the steel sheet can be heated at a rate of 52.1 to 125.0 ° C./second at a plate speed of 150 mpm, and the height is 3 This is an apparatus for producing an galvannealed steel sheet that is alloyed by an alloying furnace having an induction heating device within 0.0 m, and the temperature of the steel sheet is 20 in the range of 300 ° C. to 500 ° C. before the snout. An alloyed hot dip galvanizing characterized by having a soaking furnace that keeps soaking for more than 2 seconds, and makes the temperature difference in the width direction of the steel sheet and the temperature difference in the longitudinal direction at the welding point 5 ° C. or less on the exit side of the soaking furnace Steel plate manufacturing equipment.
(2) After hot-dip galvanizing on the surface of the cold-rolled steel sheet, the steel sheet can be heated at a rate of 52.1-125.0 ° C./second at a plate speed of 150 mpm, and the height is 3 A method for producing an alloyed hot-dip galvanized steel sheet that is alloyed by an alloying furnace having an induction heating device of less than 0.0 m, and the sheet temperature of the steel sheet is set to 300 ° C. in a soaking furnace provided in the front stage of the snout. An alloyed molten zinc characterized in that the temperature difference in the width direction of the steel sheet and the temperature difference in the longitudinal direction at the welding point are kept at 5 ° C. or less on the outlet side of the temperature equalizing furnace for 20 seconds or more in the range of 500 ° C. Manufacturing method of plated steel sheet.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the method for producing a galvannealed steel sheet according to the present invention will be described with reference to FIGS. 1, 2, 4, and 5.
FIG. 1 is a diagram showing an embodiment of an apparatus for producing an galvannealed steel sheet according to the present invention.
In FIG. 1, the cold-rolled steel sheet is annealed and cooled at a cooling rate of 70 ° C./second or more by the roll cooling device 1, and then is isothermally maintained in the soaking furnace 2 for 20 seconds or more. Through the hot dip galvanizing pot 4, hot dip galvanizing is performed on the steel sheet surface.
Although the cooling device is a roll cooling device, the effect is the same in gas cooling.
The steel sheet to which hot dip galvanization has been applied is subjected to an alloying treatment by an induction heating device 6 having a height of 3.0 m or less and a holding furnace 7 after being adjusted to an appropriate basis weight by the plating adhesion amount control device 5, and the steel plate ascending path 8 and the steel plate descending passage 9 to cool to room temperature in the water cooling bath 10.
[0010]
FIG. 2 is a diagram showing an embodiment of a method for producing an galvannealed steel sheet according to the present invention.
In FIG. 2, the horizontal axis indicates time (seconds), and the vertical axis indicates plate temperature (° C.).
After the cold rolling, the annealed steel sheet is cooled to a temperature of 500 ° C. or lower and held at that temperature for 20 seconds or more by a soaking furnace. By cooling, the temperature of the edge portion of the steel plate indicated by the dotted line in FIG. 2 or the welded portion having a small thickness is about 15 ° C. lower than the temperature of the central portion of the steel plate. It is almost lost by being held at 300 to 500 ° C. for 20 seconds or more.
The reason why the temperature is set to 300 to 500 ° C. is that this temperature range is a preferable temperature range for performing hot dipping.
[0011]
Thereafter, when the steel plate surface is galvanized with a hot dipping apparatus, this temperature difference is somewhat widened, but this temperature difference is within 5 ° C on the soaking furnace exit side (hot dipping apparatus entrance side). Therefore, even after the hot dip galvanization, even if the heating rate is rapidly increased within a range of 10 to 150 ° C./sec using an induction heating device, the temperature difference does not cause much problem.
As a result, even when the edge portion of the steel plate or the welded portion of the thin plate thickness is formed, the alloying of the steel plate surface proceeds uniformly, and the occurrence of uneven alloying on the steel plate surface can be prevented.
[0012]
FIG. 4 is a diagram illustrating the change in the plate temperature at the center portion and the edge portion of the steel plate in the furnace of the soaking furnace.
The temperature difference between the central portion and the edge portion of the steel sheet on the entrance side of the soaking furnace is 15 ° C., but the temperature difference on the exit side of the soaking furnace (11 passes) is reduced to 5 ° C.
FIG. 5 is a diagram showing a temperature change in the longitudinal direction of the steel strip before and after the soaking furnace. The right side of FIG. 5 shows the plate temperature of a steel plate having a large thickness (1.0 mm), the left side shows the plate temperature of a steel plate having a thin plate thickness (0.8 mm), and the boundary portion is welded. Shows the point.
[0013]
As can be seen from FIG. 5, there is a temperature difference of about 20 ° C. before and after the welding point in the conventional hot-dip plating apparatus entrance side and the soaking furnace entrance side of the present invention. The plate temperature on the apparatus entry side (exit side of the soaking furnace) is reduced to about 5 ° C. before and after the welding point.
[0014]
【Example】
In Table 1, the Example of the manufacturing method of the galvannealed steel plate in this invention is shown.
A steel plate having a plate thickness of 0.8 mm and a plate width of 1250 mm is cooled in a cooling zone, kept soaked in a soaking furnace for 20 seconds or more, then subjected to hot dipping, and a heating rate of 10 to 150 ° C. with an induction heating device. The alloying treatment was performed by heating in the range of.
[Table 1]
Figure 0004005841
NO.1 to NO.4 show the case where gas cooling using N2 gas is performed for cooling from leaving the annealing furnace to entering the soaking furnace at a line speed of 30 mpm. Since the line speed is slow, the in-furnace time in the soaking furnace and induction heating device is longer than in the other examples, so the temperature difference in the plate width direction and the longitudinal direction can be kept relatively small. The evaluation of the layer was ◎, and no alloying irregularities on the steel sheet surface were observed at all.
[0015]
NO.5 to NO.8 when the cooling from the annealing furnace to the soaking furnace is performed at a line speed of 150 mpm using the roll cooling method at a cooling rate of 70 ° C./sec or more. Is shown. Because the line speed is fast, the in-furnace time in the soaking furnace and the induction heating device is short, but the temperature difference in the plate width direction and the longitudinal direction can be reduced to some extent by the soaking furnace, so the evaluation of the alloyed layer is ○, Almost no alloying irregularities were observed on the surface of the steel sheet.
[0016]
No. 9 is a comparative example, and shows a case where cooling is performed slowly using gas cooling at a line speed of 30 mpm. Since the line speed is slow, the in-furnace time in the induction heating device is relatively long, but since the soaking is not performed by the soaking furnace, the temperature difference between the plate width direction and the longitudinal direction is not reduced, so the alloying layer Evaluation was (triangle | delta) and the alloying nonuniformity was recognized by the steel plate surface.
No. 10 is a comparative example, and shows a case where rapid cooling at 70 ° C./sec or more is performed using roll cooling at a line speed of 150 mpm. Because the line speed is fast, the in-furnace time in the induction heating device is short and soaking is not performed by a soaking furnace, so the temperature difference between the plate width direction and the longitudinal direction is large, so the evaluation of the alloyed layer is x. In addition, unevenness in alloying was remarkably observed on the steel sheet surface.
[0017]
【The invention's effect】
According to the present invention, there are provided an apparatus and a method for producing an alloyed hot-dip galvanized steel sheet that does not cause uneven alloying on the steel sheet surface even when rapid cooling and / or rapid heating such as roll cooling or induction heating is performed. Specifically, the following industrially useful remarkable effects can be obtained.
[0018]
1) When the steel sheet is cooled in the cooling zone and the hot dipping apparatus, as shown in FIG. 3, the temperature difference between the center part of the steel sheet and the edge parts on both sides is 5 by holding the temperature in a soaking furnace for 20 seconds or more. Since the temperature can be reduced to about 0 ° C., even if a compact alloying treatment facility by rapid heating is used, it is possible to prevent occurrence of uneven alloying on the alloyed plating surface.
2) When the steel plate is changed from a thick steel plate to a thin steel plate, the latter steel plate is easy to cool because it is thin, but the difference in steel plate temperature before and after the welding point is about 5 ° C as shown in FIG. Since it can suppress, even if it cools rapidly by roll cooling or gas cooling, generation | occurrence | production of uneven alloying can be prevented on the plating surface which carried out the alloying process.
3) By performing rapid cooling and / or rapid heating with roll cooling or induction heating device, the line speed can be set fast, and the line length of the entire equipment can be shortened while ensuring the target production volume. Therefore, the equipment cost can be significantly reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of an apparatus for producing an galvannealed steel sheet according to the present invention.
FIG. 2 of the present invention is a diagram showing an embodiment of a method for producing an galvannealed steel sheet according to the present invention.
FIG. 3 is a diagram showing a conventional method for producing a galvannealed steel sheet.
FIG. 4 is a diagram exemplifying changes in the plate temperature of the central portion and the edge portion of the steel plate in the furnace of the soaking furnace.
FIG. 5 is a diagram showing a temperature change in the longitudinal direction of the steel strip before and after the soaking furnace.
[Explanation of symbols]
1: roll cooling device,
2: Soaking furnace,
3: Snout,
4: Hot dip galvanizing pot,
5: Plating adhesion amount control device,
6: induction heating device,
7: Holding furnace,
8: Steel plate ascending path,
9: Steel plate descending path,
10: Water cooling tank

Claims (2)

冷間圧延された鋼板の表面に溶融亜鉛めっきを施した後、150mpmの通板速度における鋼板の昇温速度が52.1〜125.0℃/秒で加熱でき、高さが3.0m以内の誘導加熱装置を有する合金化炉により合金化処理を行う合金化溶融亜鉛めっき鋼板の製造装置であって、スナウトの前段に、鋼板の板温を300℃〜500℃の範囲で20秒以上均温保持し均熱炉出側で鋼板の幅方向の温度差および溶接点での長手方向の温度差を5℃以下にする均熱炉を有することを特徴とする合金化溶融亜鉛めっき鋼板の製造装置。After hot dip galvanizing on the surface of the cold-rolled steel sheet, the steel sheet can be heated at a rate of 52.1 to 125.0 ° C / second at a plate speed of 150 mpm, and the height is within 3.0 m. An apparatus for producing an alloyed hot-dip galvanized steel sheet which is alloyed by an alloying furnace having an induction heating apparatus, wherein the steel sheet temperature is equal to or higher than 20 seconds in the range of 300 ° C. to 500 ° C. before the snout. Production of an alloyed hot-dip galvanized steel sheet characterized by having a soaking furnace in which the temperature difference in the width direction of the steel sheet and the temperature difference in the longitudinal direction at the welding point are kept at 5 ° C. or less on the outlet side of the soaking furnace. apparatus. 冷間圧延された鋼板の表面に溶融亜鉛めっきを施した後、150mpmの通板速度における鋼板の昇温速度が52.1〜125.0℃/秒で加熱でき、高さが3.0m以内の誘導加熱装置を有する合金化炉により合金化処理を行う合金化溶融亜鉛めっき鋼板の製造方法であって、スナウトの前段に設けた均熱炉内で鋼板の板温を300℃〜500℃の範囲で20秒以上均温保持し均熱炉出側で鋼板の幅方向の温度差および溶接点での長手方向の温度差を5℃以下にすることを特徴とする合金化溶融亜鉛めっき鋼板の製造方法。After hot dip galvanizing on the surface of the cold-rolled steel sheet, the steel sheet can be heated at a rate of 52.1 to 125.0 ° C / second at a plate speed of 150 mpm, and the height is within 3.0 m. A method for producing an alloyed hot-dip galvanized steel sheet that is alloyed by an alloying furnace having an induction heating apparatus, wherein the temperature of the steel sheet is 300 ° C. to 500 ° C. in a soaking furnace provided at the front stage of the snout . An alloyed hot-dip galvanized steel sheet characterized in that the temperature difference is maintained for 20 seconds or more in the range, and the temperature difference in the width direction of the steel sheet and the temperature difference in the longitudinal direction at the welding point are set to 5 ° C. Production method.
JP2002142491A 2002-05-17 2002-05-17 Production apparatus and production method of alloyed hot-dip galvanized steel sheet Expired - Fee Related JP4005841B2 (en)

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