JP2017145430A - Dew point control method and method for manufacturing hot-dip galvanized steel sheet - Google Patents

Dew point control method and method for manufacturing hot-dip galvanized steel sheet Download PDF

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JP2017145430A
JP2017145430A JP2016025514A JP2016025514A JP2017145430A JP 2017145430 A JP2017145430 A JP 2017145430A JP 2016025514 A JP2016025514 A JP 2016025514A JP 2016025514 A JP2016025514 A JP 2016025514A JP 2017145430 A JP2017145430 A JP 2017145430A
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furnace
dew point
flow rate
steel sheet
correction value
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正宏 近藤
Masahiro Kondo
正宏 近藤
和敏 廣山
Kazutoshi Hiroyama
和敏 廣山
鈴木　克一
Katsuichi Suzuki
克一 鈴木
玄太郎 武田
Gentaro Takeda
玄太郎 武田
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JFE Steel Corp
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Abstract

PROBLEM TO BE SOLVED: To manufacture a hot-dip galvanized steel sheet capable of more precisely controlling a dew point and excellent in plating properties.SOLUTION: The dew point control method includes controlling a flow rate of humidified gas supplied to an annealing furnace having a heating zone, a soaking zone and a cooling zone arranged in this order using a flow rate obtained by multiplying the calculation flow rate of the humidified gas supplied to the annealing furnace by a flow rate correction value C calculated by the following formula (1) as the target flow rate of the humidified gas. C=A×B...(1), where in formula (1), A: a sheet width correction value set according to the width of a steel sheet in the furnace controlled by a host computer and B: a sheet passing speed correction value being a ratio of a reference sheet passing speed in the furnace to an actual sheet passing speed in the furnace.SELECTED DRAWING: Figure 3

Description

本発明は、連続溶融亜鉛めっき設備を用いた溶融亜鉛めっき鋼板製造時の、炉内雰囲気ガスによる露点制御方法に関する。また、本発明は、この露点制御方法を用いた溶融亜鉛めっき鋼板の製造方法に関する。   The present invention relates to a dew point control method using atmospheric gas in a furnace when a hot dip galvanized steel sheet is manufactured using a continuous hot dip galvanizing facility. Moreover, this invention relates to the manufacturing method of the hot dip galvanized steel plate using this dew point control method.

近年、自動車、家電、建材等の分野において、構造物の軽量化等に寄与可能な高張力鋼板の需要が高まっている。このような高張力鋼板としては、鋼中にＳｉを添加すると穴広げ性の良好な高張力鋼板が製造できることがわかっている。   In recent years, in the fields of automobiles, home appliances, building materials, etc., there is an increasing demand for high-tensile steel sheets that can contribute to weight reduction of structures. As such a high-strength steel plate, it has been found that when Si is added to the steel, a high-strength steel plate with good hole expanding property can be produced.

溶融亜鉛めっき鋼板は、還元雰囲気又は非酸化性雰囲気中で６００〜９００℃程度の温度で母材の鋼板を加熱焼鈍した後に、該鋼板に溶融亜鉛めっき処理を行うことによって製造される。また、合金化溶融亜鉛めっき鋼板は、溶融亜鉛めっき処理後に亜鉛めっきを加熱合金化することによって製造される。しかし、Ｓｉを多量に（特に０．２質量％以上）含有する高張力鋼板を母材として溶融亜鉛めっき鋼板や合金化溶融亜鉛めっき鋼板を製造する場合、以下の問題がある。   A hot dip galvanized steel sheet is manufactured by heat-annealing a base steel sheet at a temperature of about 600 to 900 ° C. in a reducing atmosphere or a non-oxidizing atmosphere, and then subjecting the steel sheet to a hot dip galvanizing process. Moreover, the alloyed hot-dip galvanized steel sheet is manufactured by heat-alloying galvanizing after hot-dip galvanizing treatment. However, when manufacturing a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet using a high-strength steel sheet containing a large amount of Si (particularly 0.2% by mass or more) as a base material, there are the following problems.

鋼中のＳｉは易酸化性元素であるため、一般的に用いられる還元雰囲気又は非酸化性雰囲気中でも選択酸化されて、鋼板の表面に濃化し、酸化物を形成する。この酸化物は、めっき処理時の溶融亜鉛との濡れ性を低下させて、不めっきを生じさせる。そのため、鋼中Ｓｉ濃度の増加と共に、濡れ性が急激に低下して不めっきが多発する。また、不めっきに至らなかった場合でも、めっき密着性に劣るという問題がある。さらに、鋼中のＳｉが選択酸化されて鋼板の表面に濃化すると、溶融亜鉛めっき後の合金化過程において著しい合金化遅延が生じ、生産性を著しく阻害するという問題もある。   Since Si in steel is an easily oxidizable element, it is selectively oxidized even in a generally used reducing atmosphere or non-oxidizing atmosphere, and is concentrated on the surface of the steel sheet to form an oxide. This oxide reduces wettability with molten zinc during the plating process and causes non-plating. Therefore, as the Si concentration in the steel increases, the wettability decreases sharply and non-plating occurs frequently. In addition, even when non-plating does not occur, there is a problem that the plating adhesion is poor. Further, when Si in the steel is selectively oxidized and concentrated on the surface of the steel sheet, there is a problem that a remarkable alloying delay occurs in the alloying process after hot dip galvanizing, and the productivity is remarkably hindered.

このような問題に対応するため、Ｓｉ等の易酸化性元素を多量に含む溶融亜鉛めっき鋼板の製造時に炉内雰囲気ガスの露点を制御することで、めっき密着性を高くし、良好なめっき外観を得る手法が検討されてきた。   In order to cope with such problems, by controlling the dew point of the atmosphere gas in the furnace during the production of hot dip galvanized steel sheets containing a large amount of easily oxidizable elements such as Si, the plating adhesion is improved and the appearance of the plating is good. The method of obtaining has been studied.

例えば特許文献１には、炉内ガスの露点を測定しながら、その測定値に応じて、炉内ガスの供給及び排出の位置を変化させることによって、還元炉内ガスの露点を制御して、鋼板の表面にＳｉが濃化するのを抑制する技術が記載されている。   For example, in Patent Document 1, while measuring the dew point of the gas in the furnace, the dew point of the gas in the reducing furnace is controlled by changing the position of supply and discharge of the gas in the furnace according to the measured value. A technique for suppressing the concentration of Si on the surface of a steel sheet is described.

また、特許文献２には、内部酸化が十分に起こるまでの比較的低温域での鋼板の表面濃化を抑制する技術が記載されている。特許文献２では、窒素雰囲気中に設置した水タンクを加熱して加湿した窒素ガスが流れる配管を予め別途設置し、加湿した窒素ガス中に水素ガスを導入して混合し、これを炉内に導入することで雰囲気の露点を制御している。   Patent Document 2 describes a technique for suppressing the surface concentration of a steel sheet in a relatively low temperature range until internal oxidation sufficiently occurs. In Patent Document 2, a pipe for heating and humidifying a water tank installed in a nitrogen atmosphere is separately installed in advance, and hydrogen gas is introduced into the humidified nitrogen gas and mixed, and this is put into the furnace. The dew point of the atmosphere is controlled by introducing it.

特開２００９−２０９３９７号公報JP 2009-209397 A 特開２０１１−２１９７７９号公報JP 2011-219779 A

しかし、特許文献１に記載の方法では、焼鈍炉に供給する炉内雰囲気ガスは加湿装置を用いていないため、炉内の露点は一定ではない。そのため、めっき密着性を高くすることができる露点領域になるように、安定的に露点を制御することが困難である。また、仮に露点が上昇した場合には炉上部の露点が高くなりやすく、例えば、炉下部の露点計で０℃となったときには、炉上部では＋１０℃以上の高露点雰囲気となる場合がある。仮にそのまま長期間操業すると、焼鈍炉内のロールに酸化スケールが付着し、鋼板に押し疵、いわゆるピックアップ欠陥が発生する恐れがある。   However, in the method described in Patent Document 1, since the atmosphere gas in the furnace supplied to the annealing furnace does not use a humidifier, the dew point in the furnace is not constant. For this reason, it is difficult to stably control the dew point so that the dew point region can increase the plating adhesion. Also, if the dew point rises, the dew point at the top of the furnace tends to increase. For example, when the dew point meter at the bottom of the furnace reaches 0 ° C., there may be a high dew point atmosphere of + 10 ° C. or higher at the top of the furnace. If the operation is continued for a long period of time, the oxide scale adheres to the roll in the annealing furnace, and there is a possibility that a so-called pick-up defect occurs in the steel plate.

また、特許文献２に記載の方法では、炉内雰囲気露点を制御する際に、炉内雰囲気露点を測定し、加湿した窒素ガス中に水素ガスを導入して混合し、これを炉内に導入することで露点を制御している。鋼板サイズや通板速度によって、炉内露点は変化するため、露点を安定的に制御するためには、鋼板サイズや通板速度も考慮して加湿した窒素ガスを供給し、露点を制御する必要がある。しかしながら、特許文献２では鋼板サイズや通板速度を考慮していない。また、炉内露点を測定し、それに応じて加湿ガス流量を調整するフィードバック制御のみでは、露点制御の応答が遅いため、安定的に制御することが困難である。   Further, in the method described in Patent Document 2, when controlling the furnace atmosphere dew point, the furnace atmosphere dew point is measured, hydrogen gas is introduced into and mixed with humidified nitrogen gas, and this is introduced into the furnace. By controlling the dew point. Since the dew point in the furnace changes depending on the steel plate size and the plate passing speed, in order to control the dew point stably, it is necessary to supply humidified nitrogen gas in consideration of the steel plate size and the plate passing speed to control the dew point. There is. However, Patent Document 2 does not take into consideration the steel plate size or the plate passing speed. In addition, it is difficult to control stably only by feedback control that measures the dew point in the furnace and adjusts the humidified gas flow rate accordingly, because the response of the dew point control is slow.

本発明は、かかる事情に鑑み、露点をより精密に制御し、めっき性に優れる溶融亜鉛めっき鋼板を製造することを目的とする。   In view of such circumstances, an object of the present invention is to produce a hot-dip galvanized steel sheet that has a more precise dew point and is excellent in plating properties.

本発明者らは、鋭意検討した結果、鋼板サイズや通板速度を考慮する必要があると考えた。その結果、連続溶融亜鉛めっき設備を用いた溶融亜鉛めっき鋼板製造時の炉内雰囲気ガスの露点を制御する際に、炉内に供給される加湿ガスの計算流量に、炉内の鋼板の板幅補正値Ａ［ｍｍ］と通板速度補正値Ｂ［ｍｐｍ］に基づき決定される流量補正値Ｃを乗じたものを加湿ガスの目標流量として炉内に供給される加湿ガス流量を調整することで、露点をより精密に制御し、めっき性に優れる溶融亜鉛めっき鋼板を製造することを見出した。   As a result of intensive studies, the present inventors have considered that it is necessary to consider the steel plate size and plate passing speed. As a result, when controlling the dew point of the atmospheric gas in the furnace during the production of hot dip galvanized steel sheets using a continuous hot dip galvanizing facility, the calculated flow rate of the humidified gas supplied into the furnace is set to the plate width of the steel sheets in the furnace. By adjusting the flow rate of the humidified gas supplied into the furnace with the product of the correction value A [mm] and the flow rate correction value C determined based on the plate feed speed correction value B [mpm] as the target flow rate of the humidified gas. The present inventors have found that a hot-dip galvanized steel sheet with excellent dew point is produced by controlling the dew point more precisely.

上記課題を解決するための本発明の要旨は、以下のとおりである。
［１］加熱帯と、均熱帯と、冷却帯とがこの順に配置される焼鈍炉において、
前記焼鈍炉内に供給される加湿ガスの計算流量に、下記式（１）で算出される流量補正値Ｃを乗じたものを加湿ガスの目標流量として炉内に供給する加湿ガスの流量調整を行うことを特徴とする露点制御方法。
Ｃ＝Ａ×Ｂ・・・（１）
式（１）において、
Ａ：上位計算機で管理される炉内の鋼板の板幅に応じて設定される板幅補正値
Ｂ：炉内の基準通板速度と実際の炉内の通板速度との比である通板速度補正値
である。
［２］［１］に記載の露点制御方法を用いて鋼板を焼鈍した後、前記焼鈍炉に隣接される溶融亜鉛めっき設備にて溶融亜鉛めっきを施すことを特徴とする溶融亜鉛めっき鋼板の製造方法。 The gist of the present invention for solving the above problems is as follows.
[1] In an annealing furnace in which a heating zone, a soaking zone, and a cooling zone are arranged in this order,
Adjusting the flow rate of the humidified gas supplied into the furnace by multiplying the calculated flow rate of the humidified gas supplied into the annealing furnace by the flow rate correction value C calculated by the following equation (1) as the target flow rate of the humidified gas The dew point control method characterized by performing.
C = A × B (1)
In equation (1),
A: Plate width correction value set according to the plate width of the steel plate in the furnace managed by the host computer B: Feed plate which is the ratio of the reference plate speed in the furnace and the actual plate speed in the furnace This is the speed correction value.
[2] Manufacture of a hot dip galvanized steel sheet, wherein the steel sheet is annealed using the dew point control method according to [1] and then hot dip galvanized in a hot dip galvanizing facility adjacent to the annealing furnace. Method.

本発明によれば、連続溶融亜鉛めっき設備を用いた溶融亜鉛めっき鋼板製造時の炉内雰囲気ガスの露点をより精密に制御することができる。したがって、本発明の露点制御方法を用いることにより、めっき密着性を高くし、良好なめっき外観を有する溶融亜鉛めっき鋼板を得ることができる。   ADVANTAGE OF THE INVENTION According to this invention, the dew point of the atmospheric gas in a furnace at the time of hot-dip galvanized steel plate manufacture using a continuous hot-dip galvanization equipment can be controlled more precisely. Therefore, by using the dew point control method of the present invention, it is possible to obtain a hot dip galvanized steel sheet having high plating adhesion and a good plating appearance.

なお、本発明における溶融亜鉛めっき鋼板とは、合金化しない溶融亜鉛めっき鋼板と合金化した合金化溶融亜鉛めっき鋼板の両方を意味する。   In addition, the hot dip galvanized steel sheet in this invention means both the hot dip galvanized steel sheet which is not alloyed and the alloyed hot dip galvanized steel sheet.

図１は、本発明の連続溶融亜鉛めっき設備の焼鈍炉および溶融亜鉛めっき装置の構成を示す模式図である。FIG. 1 is a schematic diagram showing a configuration of an annealing furnace and a hot dip galvanizing apparatus of a continuous hot dip galvanizing facility according to the present invention. 図２は、本発明における焼鈍炉内へ供給するガスのフロー図である。FIG. 2 is a flow diagram of gas supplied into the annealing furnace in the present invention. 図３は、焼鈍炉内に供給される混合ガスの制御ブロック図である。FIG. 3 is a control block diagram of the mixed gas supplied into the annealing furnace. 図４は、本発明の露点制御方法で制御した場合と、従来の露点制御方法で制御した場合の炉内露点の変化を比較したシミュレーション結果である。FIG. 4 is a simulation result comparing changes in the dew point in the furnace when controlled by the dew point control method of the present invention and when controlled by the conventional dew point control method.

以下、図面を参照して、本発明について説明する。   Hereinafter, the present invention will be described with reference to the drawings.

図１は、本発明の連続溶融亜鉛めっき設備の焼鈍炉および溶融亜鉛めっき装置の構成を示す模式図である。焼鈍炉１内では、加熱帯２、均熱帯３および冷却帯４がこの順に配置される。溶融亜鉛めっき装置５は冷却帯４に隣接し、溶融亜鉛めっき浴６と、溶融亜鉛めっき後の鋼板を合金化するための合金化炉７とを有する。   FIG. 1 is a schematic diagram showing a configuration of an annealing furnace and a hot dip galvanizing apparatus of a continuous hot dip galvanizing facility according to the present invention. In the annealing furnace 1, a heating zone 2, a soaking zone 3, and a cooling zone 4 are arranged in this order. The hot dip galvanizing apparatus 5 is adjacent to the cooling zone 4 and has a hot dip galvanizing bath 6 and an alloying furnace 7 for alloying the hot dip galvanized steel sheet.

図２は、本発明における、焼鈍炉内へ供給するガスのフロー図である。本発明では、焼鈍炉１の均熱帯３に乾燥ガスおよび混合ガスが供給される（以下、焼鈍炉または均熱帯を単に「炉」と称することもある。）。具体的には、ガス供給管８から乾燥ガス供給管９および混合ガス供給管１０が分岐して、乾燥ガスおよび混合ガスが炉内へ供給される。乾燥ガスの流量は、乾燥ガス用流量調節弁１１により調整される。そして、所定量の乾燥ガスが乾燥ガス投入口１２により炉内へ供給される。乾燥ガスは、露点が−６０℃〜−５０℃程度のＨ２−Ｎ２ガス、またはＮ２ガスである。 FIG. 2 is a flow diagram of the gas supplied into the annealing furnace in the present invention. In the present invention, the dry gas and the mixed gas are supplied to the soaking zone 3 of the annealing furnace 1 (hereinafter, the annealing furnace or soaking zone may be simply referred to as “furnace”). Specifically, the dry gas supply pipe 9 and the mixed gas supply pipe 10 branch from the gas supply pipe 8, and the dry gas and the mixed gas are supplied into the furnace. The flow rate of the dry gas is adjusted by the flow rate control valve 11 for dry gas. Then, a predetermined amount of dry gas is supplied into the furnace through the dry gas inlet 12. The dry gas is H 2 —N 2 gas or N 2 gas having a dew point of about −60 ° C. to −50 ° C.

混合ガス供給管１０については、ガス供給管８から供給された乾燥ガスの一部が加湿装置１３により加湿される。そして、乾燥ガスと、加湿装置１３により加湿されたガス（以下、単に加湿ガスと称することもある。）が混合されて、混合ガスとなる。混合ガスは、炉内の容積等のライン仕様に合わせた所定の混合比で混合され、所定の露点とされる。   As for the mixed gas supply pipe 10, a part of the dry gas supplied from the gas supply pipe 8 is humidified by the humidifier 13. Then, the dry gas and the gas humidified by the humidifier 13 (hereinafter sometimes simply referred to as humidified gas) are mixed to form a mixed gas. The mixed gas is mixed at a predetermined mixing ratio according to line specifications such as the volume in the furnace, and a predetermined dew point is obtained.

なお、混合ガスの露点は混合ガス用露点計１４で監視される。混合ガスの流量は、混合ガス用流量調節弁１５により調整され、所定量の混合ガスが混合ガス投入口１６により炉内へ供給される。また、混合ガスの投入量は、炉内に設置されている炉内ガス露点計１７の値に基づき、混合ガス用流量調節弁１５により調整される。なお、乾燥ガス供給管９から炉内に供給する乾燥ガスの流量を炉内の容積等のライン仕様から予め決定しておき、この流量となるように乾燥ガス用流量調節弁１１の開度が調節される。そして、混合ガス供給管１０から混合ガスを炉内に供給することで、炉内において、乾燥ガスと混合ガスとが混ざり合い、所定の露点が得られることとなる。   The dew point of the mixed gas is monitored by a mixed gas dew point meter 14. The flow rate of the mixed gas is adjusted by the mixed gas flow control valve 15, and a predetermined amount of the mixed gas is supplied into the furnace through the mixed gas inlet 16. Further, the amount of the mixed gas input is adjusted by the mixed gas flow control valve 15 based on the value of the in-furnace gas dew point meter 17 installed in the furnace. The flow rate of the dry gas supplied from the dry gas supply pipe 9 into the furnace is determined in advance from line specifications such as the volume in the furnace, and the opening degree of the dry gas flow control valve 11 is set so as to be this flow rate. Adjusted. Then, by supplying the mixed gas from the mixed gas supply pipe 10 into the furnace, the dry gas and the mixed gas are mixed in the furnace, and a predetermined dew point is obtained.

図３は、炉内に供給する混合ガスの制御ブロック図である。本発明では、炉内の露点を制御するために、露点調節器と流量調節器が設けられる。炉内に供給する混合ガス量は、炉圧変動等の外乱の影響を受けるため、露点調節器のみでは露点を精密に制御することができない。そこで、露点調節計と流量調節計を用いて制御を行うことにより、外乱の影響を最小限とすることができる。なお、炉内の露点を制御する際には、流量調節弁１５の弁開度を適宜調整することにより、炉内に供給する混合ガス量を調整する。   FIG. 3 is a control block diagram of the mixed gas supplied into the furnace. In the present invention, a dew point adjuster and a flow rate adjuster are provided to control the dew point in the furnace. Since the amount of gas mixture supplied into the furnace is affected by disturbances such as fluctuations in furnace pressure, the dew point cannot be precisely controlled only by the dew point controller. Therefore, the influence of disturbance can be minimized by performing control using a dew point controller and a flow controller. In addition, when controlling the dew point in a furnace, the amount of mixed gas supplied into a furnace is adjusted by adjusting the valve opening degree of the flow control valve 15 suitably.

露点調節器に入力されるのは、目標となる炉内露点（目標露点）と、露点計１７で計測される現在の炉内露点のフィードバック値の差分である。露点調節器から出力されるのは、目標の炉内露点になるように供給されるべき加湿ガスの計算流量である。本発明では、この計算流量に流量補正値Ｃを乗じた流量を目標流量とすることを特徴とする。具体的には、この目標流量と、流量計（図示しない）で測定される実際の加湿ガス流量との差分をとったものを流量調節器の入力とする。そして、流量調節弁１５の弁開度を調整し、加湿ガス流量（制御対象１）を調整することで、炉内露点（制御対象２）を制御する。   What is input to the dew point adjuster is the difference between the target in-furnace dew point (target dew point) and the current in-furnace dew point feedback value measured by the dew point meter 17. The output from the dew point adjuster is the calculated flow rate of the humidified gas to be supplied so as to achieve the target furnace dew point. In the present invention, a flow rate obtained by multiplying the calculated flow rate by a flow rate correction value C is set as a target flow rate. Specifically, the difference between the target flow rate and the actual humidified gas flow rate measured by a flow meter (not shown) is taken as the input of the flow rate regulator. And the dew point in the furnace (control object 2) is controlled by adjusting the valve opening degree of the flow control valve 15 and adjusting the humidified gas flow rate (control object 1).

流量補正値Ｃは、下記式（１）で算出される。
Ｃ＝Ａ×Ｂ・・・（１）
式（１）において、
Ａ：上位計算機で管理される炉内の鋼板の板幅に応じて設定される板幅補正値
Ｂ：炉内の基準通板速度と実際の炉内の通板速度との比である通板速度補正値
である。 The flow rate correction value C is calculated by the following equation (1).
C = A × B (1)
In equation (1),
A: Plate width correction value set according to the plate width of the steel plate in the furnace managed by the host computer B: Feed plate which is the ratio of the reference plate speed in the furnace and the actual plate speed in the furnace This is the speed correction value.

板幅補正値Ａは、上位計算機で管理される。上位計算機には、板幅に応じた板幅補正値Ａの設定テーブルがあり、現在炉内にある鋼板の板幅に応じた板幅補正値Ａを設定テーブルから選択する。板幅補正値Ａの設定テーブルは、炉に挿入される板幅情報、炉の容積、操業条件等を考慮してライン仕様毎に予め設定される。   The plate width correction value A is managed by a host computer. The host computer has a setting table for the plate width correction value A corresponding to the plate width, and the plate width correction value A corresponding to the plate width of the steel plate currently in the furnace is selected from the setting table. The setting table of the plate width correction value A is set in advance for each line specification in consideration of the plate width information inserted into the furnace, the furnace volume, operating conditions, and the like.

また、通板速度補正値Ｂは、炉内の基準通板速度と現在の炉内の通板速度の比である。現在の炉内の通板速度は、搬送ロールに設置されたＰＬＧ（パルスジェネレータ）により測定される通板速度実績である。板幅補正値Ａと通板速度補正値Ｂを算出し、これらを乗じることで流量補正値Ｃを算出する。   Further, the plate passing speed correction value B is a ratio of the reference plate passing speed in the furnace and the current plate passing speed in the furnace. The current plate-passing speed in the furnace is the actual plate-passing speed measured by a PLG (pulse generator) installed on the transport roll. A plate width correction value A and a plate speed correction value B are calculated, and the flow rate correction value C is calculated by multiplying these values.

露点を安定的に制御するためには、鋼板サイズや通板速度も考慮して加湿した窒素ガスまたはＨ２−Ｎ２ガスを供給し、露点を制御する必要がある。本発明のように、板幅情報に基づく板幅補正値Ａと、通板速度の情報（速度実績）に基づく通板速度補正値Ｂとで表される流量補正値Ｃを、加湿ガスの計算流量に乗じることにより、鋼板サイズや通板速度を考慮することができる。その結果、焼鈍炉内の露点をより精密に制御することができる。 In order to stably control the dew point, it is necessary to control the dew point by supplying humidified nitrogen gas or H 2 —N 2 gas in consideration of the steel plate size and the plate passing speed. As in the present invention, the flow rate correction value C represented by the plate width correction value A based on the plate width information and the plate passing speed correction value B based on the plate passing speed information (speed record) is calculated as the humidified gas. By multiplying the flow rate, the steel plate size and the plate passing speed can be taken into consideration. As a result, the dew point in the annealing furnace can be controlled more precisely.

以上より、本発明では、加湿ガスの計算流量に流量補正値Ｃを乗じて、炉内に供給する加湿ガス流量を調整することにより焼鈍炉内の露点をより精密に制御することができる。また、本発明の炉内雰囲気ガスの露点制御方法を用いて溶融亜鉛めっき鋼板または合金化溶融亜鉛めっき鋼板を製造することにより、めっき密着性が高く良好なめっき外観を有する、めっき性に優れた溶融亜鉛めっき鋼板または合金化溶融亜鉛めっき鋼板を得ることができる。   As described above, in the present invention, the dew point in the annealing furnace can be controlled more precisely by multiplying the calculated flow rate of the humidified gas by the flow rate correction value C and adjusting the flow rate of the humidified gas supplied into the furnace. In addition, by producing a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet using the method for controlling the dew point of the atmospheric gas in the furnace according to the present invention, the plating adhesion is high, the plating appearance is good, and the plating property is excellent. A hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet can be obtained.

なお、合金化溶融亜鉛めっき鋼板の製造条件については特に制限はなく、常法の方法により製造することができる。   In addition, there is no restriction | limiting in particular about the manufacturing conditions of a galvannealed steel plate, It can manufacture by a conventional method.

Ｓｉを０．２質量％以上含む高張力鋼板を製造するにあたり、本発明の露点制御方法で制御した場合の炉内露点の変化と、従来の露点制御方法（加湿ガスの計算流量を目標流量とする。すなわち、計算流量に流量補正値Ｃを乗じずに露点制御をする。）で制御した場合の炉内露点の変化を比較するシミュレーション実験を行った。ここで、炉内目標露点は−２０℃とした。また、シミュレーションでは経過時間が３０分で炉内通板速度が基準速度より低下し、経過時間が６０分のときに炉内通板速度が基準速度に戻ると仮定した。また、通板させる鋼板は、板幅：１２００ｍｍ、通板速度９０ｍｐｍとした。基準板幅は１３５０ｍｍ、基準速度は９０ｍｐｍとした。基準板幅を１としたときの板幅の変化の割合をＡ、基準速度を１としたときの通板速度の変化の割合をＢとして流量補正値Ｃを算出し、露点制御を行った（Ａ＝０．８９）。   In producing a high strength steel sheet containing 0.2 mass% or more of Si, the change in the dew point in the furnace when controlled by the dew point control method of the present invention, and the conventional dew point control method (the calculated flow rate of the humidified gas as the target flow rate). In other words, a simulation experiment was performed to compare changes in the dew point in the furnace when the calculated flow rate was controlled without multiplying the calculated flow rate by the flow rate correction value C.). Here, the target dew point in the furnace was −20 ° C. In the simulation, it was assumed that the passage speed in the furnace decreased from the reference speed after 30 minutes and the passage speed in the furnace returned to the reference speed when the elapsed time was 60 minutes. Moreover, the steel plate to be passed was set to a plate width of 1200 mm and a plate passing speed of 90 mpm. The reference plate width was 1350 mm and the reference speed was 90 mpm. The flow rate correction value C was calculated with the rate of change in plate width when the reference plate width was 1 as A, and the rate of change in plate speed when the reference speed was 1 as B, and dew point control was performed ( A = 0.89).

図４は、シミュレーション結果である。本発明の露点制御方法も従来の露点制御方法も、炉内通板速度が低下した経過時間３０分で炉内露点が上昇し始めた。本発明の露点制御方法は目標露点である−２０℃付近にすぐに戻っており、露点が制御されていることがわかる。一方、従来の露点制御方法は、目標露点である−２０℃に戻るのに時間がかかっていることがわかる。   FIG. 4 shows a simulation result. In both the dew point control method of the present invention and the conventional dew point control method, the in-furnace dew point began to increase after 30 minutes when the in-furnace plate speed decreased. The dew point control method of the present invention immediately returns to around the target dew point of −20 ° C., indicating that the dew point is controlled. On the other hand, it can be seen that the conventional dew point control method takes time to return to the target dew point of −20 ° C.

また、本発明の露点制御方法を用いて常法により溶融亜鉛めっき鋼板および合金化溶融亜鉛めっき鋼板を製造したところ、めっき密着性およびめっき外観に優れた溶融亜鉛めっき鋼板および合金化溶融亜鉛めっき鋼板を得ることができた。   Moreover, when a hot-dip galvanized steel sheet and an alloyed hot-dip galvanized steel sheet were produced by a conventional method using the dew point control method of the present invention, a hot-dip galvanized steel sheet and an alloyed hot-dip galvanized steel sheet excellent in plating adhesion and plating appearance were obtained. Could get.

１ 焼鈍炉
２ 加熱帯
３ 均熱帯
４ 冷却帯
５ 溶融亜鉛めっき装置
６ 溶融亜鉛めっき浴
７ 合金化炉
８ 窒素ガス供給管
９ 乾燥ガス供給管
１０ 混合ガス供給管
１１ 乾燥ガス用流量調節弁
１２ 乾燥ガス投入口
１３ 加湿装置
１４ 混合ガス用露点計
１５ 混合ガス用流量調節弁
１６ 混合ガス投入口
１７ 炉内ガス露点計 DESCRIPTION OF SYMBOLS 1 Annealing furnace 2 Heating zone 3 Soaking zone 4 Cooling zone 5 Hot dip galvanizing apparatus 6 Hot dip galvanizing bath 7 Alloying furnace 8 Nitrogen gas supply pipe 9 Drying gas supply pipe 10 Mixed gas supply pipe 11 Drying gas flow control valve 12 Drying Gas inlet 13 Humidifier 14 Dew point meter for mixed gas 15 Flow control valve for mixed gas 16 Mixed gas inlet 17 Gas dew point meter in furnace

Claims (2)

加熱帯と、均熱帯と、冷却帯とがこの順に配置される焼鈍炉において、
前記焼鈍炉内に供給される加湿ガスの計算流量に、下記式（１）で算出される流量補正値Ｃを乗じたものを加湿ガスの目標流量として炉内に供給する加湿ガスの流量調整を行うことを特徴とする露点制御方法。
Ｃ＝Ａ×Ｂ・・・（１）
式（１）において、
Ａ：上位計算機で管理される炉内の鋼板の板幅に応じて設定される板幅補正値
Ｂ：炉内の基準通板速度と実際の炉内の通板速度との比である通板速度補正値
である。 In an annealing furnace in which a heating zone, a soaking zone, and a cooling zone are arranged in this order,
Adjusting the flow rate of the humidified gas supplied into the furnace by multiplying the calculated flow rate of the humidified gas supplied into the annealing furnace by the flow rate correction value C calculated by the following equation (1) as the target flow rate of the humidified gas The dew point control method characterized by performing.
C = A × B (1)
In equation (1),
A: Plate width correction value set according to the plate width of the steel plate in the furnace managed by the host computer B: Feed plate which is the ratio of the reference plate speed in the furnace and the actual plate speed in the furnace This is the speed correction value. 請求項１に記載の露点制御方法を用いて鋼板を焼鈍した後、前記焼鈍炉に隣接される溶融亜鉛めっき設備にて溶融亜鉛めっきを施すことを特徴とする溶融亜鉛めっき鋼板の製造方法。   A method for producing a hot dip galvanized steel sheet, comprising subjecting a steel sheet to annealing using the dew point control method according to claim 1 and then performing hot dip galvanizing in a hot dip galvanizing facility adjacent to the annealing furnace.
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* Cited by examiner, † Cited by third party
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CN115029527A (en) * 2022-04-27 2022-09-09 首钢智新迁安电磁材料有限公司 Control method for steam dew point of humidifier
CN115058570A (en) * 2022-06-22 2022-09-16 首钢集团有限公司 Annealing furnace area dew point control method, device and system and electronic equipment

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JP2000064006A (en) * 1998-08-13 2000-02-29 L'air Liquide Galvanization of metallic strip
JP2000219952A (en) * 1999-02-01 2000-08-08 Sumitomo Metal Ind Ltd PRODUCTION OF Zn-Al-Si ALLOY PLATED STEEL SHEET EXCELLENT IN DESIGNING PROPERTY

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JPH07138658A (en) * 1993-11-15 1995-05-30 Nippon Steel Corp Device for controlling dew point in continuous heat treatment furnace
JP2000064006A (en) * 1998-08-13 2000-02-29 L'air Liquide Galvanization of metallic strip
JP2000219952A (en) * 1999-02-01 2000-08-08 Sumitomo Metal Ind Ltd PRODUCTION OF Zn-Al-Si ALLOY PLATED STEEL SHEET EXCELLENT IN DESIGNING PROPERTY

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Publication number Priority date Publication date Assignee Title
CN115029527A (en) * 2022-04-27 2022-09-09 首钢智新迁安电磁材料有限公司 Control method for steam dew point of humidifier
CN115029527B (en) * 2022-04-27 2023-09-19 首钢智新迁安电磁材料有限公司 Control method for steam dew point of humidifier
CN115058570A (en) * 2022-06-22 2022-09-16 首钢集团有限公司 Annealing furnace area dew point control method, device and system and electronic equipment

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