JP2005169458A - Method for heat-treating steel sheet - Google Patents

Method for heat-treating steel sheet Download PDF

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JP2005169458A
JP2005169458A JP2003413236A JP2003413236A JP2005169458A JP 2005169458 A JP2005169458 A JP 2005169458A JP 2003413236 A JP2003413236 A JP 2003413236A JP 2003413236 A JP2003413236 A JP 2003413236A JP 2005169458 A JP2005169458 A JP 2005169458A
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induction heating
heating device
steel sheet
steel plate
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JP4305156B2 (en
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Yukio Takashima
由紀雄 高嶋
Yoshimichi Hino
善道 日野
Masatoshi Sugioka
正敏 杉岡
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JFE Steel Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To keep failure caused by the deformation of a steel sheet which is represented by slitting camber within an allowable value by reducing residual stress when a heat treatment is performed by heating the steel sheet after rolling or accelerated cooling. <P>SOLUTION: In the heat-treating method by which the steel sheet after rolling or accelerated cooling is heated by using a induction heating device arranged on a rolling line, when expressing a time from the point of time when the heating of a preceding steel sheet to be heat-treated with the induction heating device is started till the next steel sheet heat-treated following the preceding steel sheet reaches the induction heating device by T<SB>1</SB>sec, the passing speed of the preceding steel sheet when the sheet passes through the induction heating device is decided so that the heating time of the preceding steel sheet in the induction heating device becomes ≥ 0.7×T<SB>1</SB>sec and the heating output of the induction heating device is decided so that it becomes electric power charging power when the surface temperature of the preceding steel sheet does not exceed the allowable temperature at the passing speed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

この発明は、圧延後または加速冷却後の鋼板を加熱して熱処理する際に、残留応力を低減し、条切りキャンバーに代表される鋼板の変形による不具合を許容値内とするのに好適な熱処理方法に関するものである。   This invention is a heat treatment suitable for reducing the residual stress when heating a steel plate after rolling or after accelerated cooling to reduce a residual stress, and to make a defect due to deformation of the steel plate represented by a cut-off camber within an allowable value. It is about the method.

熱間圧延鋼板は、素材となるスラブ等の鋼片を加熱炉で再加熱した後、高圧水によるデスケーリングでスケールを除去しながら圧延機により熱間圧延され、所望の板厚、板幅、長さとなる。その後、必要に応じて加速冷却が行われ、さらに冷却床にて冷却された後、所定の寸法に切断されて製品となる。   The hot-rolled steel sheet is re-heated in a heating furnace with a steel piece such as a slab as a raw material, and then hot-rolled by a rolling mill while removing the scale by descaling with high-pressure water, and the desired thickness, width, It becomes length. Thereafter, accelerated cooling is performed as necessary, and after further cooling in the cooling bed, the product is cut into a predetermined size to obtain a product.

このような鋼板の製造プロセスにおいて、板幅方向の鋼板温度は、鋼板側面からも冷却を受けることから、一般に板幅端部において温度が低い分布を持っている。   In such a steel plate manufacturing process, the steel plate temperature in the plate width direction is also cooled from the side surface of the steel plate, and therefore generally has a low temperature distribution at the plate width end.

また、近年、制御圧延後に鋼板を強水冷することにより高強度、高靭性鋼板を得る加速冷却技術が広く行われるようになってきている。加速冷却は、従来の添加元素成分を低減して製造コストを大幅に削減できるのみならず、溶接性にも優れた鋼板を製造することが可能となる。加速冷却においては、高温の鋼板表面に冷却ノズルより冷却水を噴射し、鋼板表面の対流沸騰熱伝達現象により自然放冷の数百倍の高冷却速度を達成させ、より微細な結晶構造を有する鋼板、すなわち、高強度、高靭性の鋼板を製造することが可能となる。   In recent years, an accelerated cooling technique for obtaining a high-strength, high-toughness steel sheet by strongly cooling the steel sheet after controlled rolling has been widely performed. Accelerated cooling can not only greatly reduce the manufacturing cost by reducing the conventional additive element components, but also can produce a steel sheet having excellent weldability. In accelerated cooling, cooling water is sprayed from a cooling nozzle onto the surface of a hot steel plate, and a high cooling rate several hundred times that of natural cooling is achieved by the convection boiling heat transfer phenomenon on the surface of the steel plate, resulting in a finer crystal structure. A steel plate, that is, a steel plate having high strength and high toughness can be produced.

しかし、加速冷却は、その高冷却性ゆえに特に板端部近傍においては鋼板が冷えやすいため、板幅端部の温度降下を助長する傾向がある。このような板幅方向の温度分布が発生すると、耳伸びや腹伸びなどの形状不良や残留応力による条切り時の横曲がり、すなわち、条切りキャンバーが発生するという問題が生じる。   However, accelerated cooling tends to promote a temperature drop at the end of the plate width because the steel plate tends to cool, particularly in the vicinity of the end of the plate, due to its high cooling ability. When such a temperature distribution in the plate width direction is generated, there arises a problem that a shape failure such as an ear extension or an abdominal extension or a lateral bending at the time of cutting due to residual stress, that is, a cutting camber occurs.

このような問題を解決するために、例えば、特許文献１には、板の幅方向温度分布を計測して加熱、冷却により鋼板の板幅方向温度分布を均一にすることが示されている。   In order to solve such a problem, for example, Patent Document 1 discloses that the temperature distribution in the width direction of the plate is measured, and the temperature distribution in the width direction of the steel plate is made uniform by heating and cooling.

この方法では、鋼板の加熱は板エッジ部の局部加熱によって行うものであるが、このような局部加熱装置以外にも、加熱装置としては鋼板を全周覆ったコイルの中を通過させながら鋼板の加熱を行うソノレイド型の誘導加熱装置がある。ソノレイド型誘導加熱装置では鋼板全周の表面が加熱されるが、板幅端部は側面からの発熱があるため、板厚平均温度を見ると、板幅方向では板端部近傍で特に温度上昇が大きく、圧延後や加速冷却後の板幅端部の温度降下を補償することが可能である。ところが、特許文献１の技術では、このようなソノレイド型誘導加熱装置を用いてどのように鋼板の加熱条件を決定すればよいかが開示されていなかった。   In this method, the steel plate is heated by local heating at the edge of the plate. In addition to such a local heating device, the heating device can be heated while passing through a coil covering the entire circumference of the steel plate. There is a sonolide type induction heating device that performs heating. The surface of the entire circumference of the steel plate is heated by the sono-red type induction heating device, but the plate width end part generates heat from the side surface, so when looking at the plate thickness average temperature, the temperature rises particularly near the plate end part in the plate width direction It is possible to compensate for the temperature drop at the end of the plate width after rolling or after accelerated cooling. However, the technique of Patent Document 1 does not disclose how to determine the heating condition of the steel sheet using such a sonolide type induction heating apparatus.

また、本出願人による特許文献２には、ソノレイド型誘導加熱装置を用いて鋼板を加熱する場合に、板端部の温度が板幅中央部に比べて高くなり、板幅方向端部の過加熱が問題となることが示され、その対策として加熱中または加熱直後に鋼板の板側端部を冷却する技術が開示されている。   Further, in Patent Document 2 by the present applicant, when a steel plate is heated using a sonolide type induction heating device, the temperature at the plate end becomes higher than that at the central portion of the plate width, and the excess at the end in the plate width direction. It has been shown that heating becomes a problem, and a technique for cooling the plate side end of the steel sheet during heating or immediately after heating is disclosed as a countermeasure.

特開２００１−２３９３１２号公報Japanese Patent Laid-Open No. 2001-239312 特開２００２−３１７２２７号公報JP 2002-317227 A

前述の通り、特許文献１には、板エッジの局部加熱を行う方法が記載されているものの、鋼板全周を加熱するソノレイド型誘導加熱装置については、温度制御方法が開示されていなかった。   As described above, Patent Document 1 describes a method of locally heating a plate edge, but does not disclose a temperature control method for a sonolide type induction heating apparatus that heats the entire circumference of a steel plate.

また、特許文献２には、ソノレイド型誘導加熱装置による板幅端部の過加熱が問題とされているものの、その制御方法として板幅端部の冷却を行うものであり、板幅方向の温度差を最小化する場合には最適な方法ではない場合があった。   Patent Document 2 discloses that the overheating of the plate width end by the sonolide type induction heating device is a problem, but the control is performed by cooling the plate width end. When minimizing the difference, it may not be the optimal method.

従って、この発明の目的は、ソノレイド型誘導加熱装置を用いて、鋼板の幅方向の温度分布を最小化し、これにより鋼板に発生する残留応力を低減し、条切りキャンバーに代表される鋼板の変形不具合を防止する熱処理時の加熱方法を提供することにあり、製造ラインの能率を阻害せず、また板幅端部の水冷を使用しない鋼板の加熱方法である。   Accordingly, the object of the present invention is to minimize the temperature distribution in the width direction of the steel sheet by using the sonolide type induction heating device, thereby reducing the residual stress generated in the steel sheet, and deforming the steel sheet represented by the cut-off camber. The object of the present invention is to provide a heating method at the time of heat treatment for preventing defects, which is a heating method for a steel plate that does not impede the efficiency of the production line and does not use water cooling at the end of the plate width.

この発明は、上述の目的を達成するためになされたものであり、下記を特徴とするものである。   The present invention has been made to achieve the above-described object, and is characterized by the following.

請求項１記載の発明は、圧延または加速冷却後の鋼板を、圧延ライン上に配置した誘導加熱装置を用いて加熱する鋼板の熱処理方法において、前記誘導加熱装置により熱処理される先の鋼板の加熱開始時点から、前記先の鋼板に続いて熱処理される次の鋼板が前記誘導加熱装置に到達するまでの時間をＴ1秒としたときに、前記先の鋼板の前記誘導加熱装置での加熱時間が０．７×Ｔ1秒以上となるように、前記誘導加熱装置を通過する前記先の鋼板の通板速度を決定し、前記誘導加熱装置の加熱出力は、前記通板速度において前記先の鋼板の表面温度が許容温度を超えない電力投入パワーとなるよう決定することに特徴を有するものである。 The invention according to claim 1 is a method for heat-treating a steel plate that is heat-treated by the induction heating device in a heat treatment method for a steel plate that heats the steel plate after rolling or accelerated cooling using an induction heating device disposed on a rolling line. When the time from the start time until the next steel plate to be heat-treated following the previous steel plate reaches the induction heating device is T 1 second, the heating time of the previous steel plate in the induction heating device Is determined to be 0.7 × T 1 second or more, the plate passing speed of the previous steel plate passing through the induction heating device is determined, and the heating output of the induction heating device is the previous plate passing speed at the plate passing speed. It is characterized in that the surface temperature of the steel sheet is determined to be the power input power that does not exceed the allowable temperature.

請求項２記載の発明は、圧延または加速冷却後の鋼板を、圧延ライン上に配置した誘導加熱装置を用いて加熱した後、ホットレベラにより熱間矯正する、鋼板の熱処理方法において、前記誘導加熱装置により熱処理される先の鋼板の加熱開始時点から、前記先の鋼板に続いて熱処理される次の鋼板が前記誘導加熱装置に到達するまでの時間をＴ1秒とし、Ｔ１秒から前記ホットレベラを通過するのに必要な時間を差し引いた時間をＴ2秒としたときに、前記先の鋼板の前記誘導加熱装置での加熱時間が０．７×Ｔ2秒以上となるように、前記誘導加熱装置を通過する前記先の鋼板の通板速度を決定し、前記誘導加熱装置の加熱出力は、前記通板速度において前記先の鋼板の表面温度が許容温度を超えない電力投入パワーとなるよう決定することに特徴を有するものである。 The invention according to claim 2 is a heat treatment method for a steel sheet, in which the steel sheet after rolling or accelerated cooling is heated using an induction heating apparatus arranged on a rolling line and then hot-corrected by a hot leveler. the heating start time of the preceding steel sheet is heat treated by, the time until the next steel sheet is heat treated subsequent to the destination of the steel sheet reaches the induction heating apparatus as T 1 seconds, the Hottorebera from T 1 seconds When the time obtained by subtracting the time necessary for passing is T 2 seconds, the induction heating is performed so that the heating time of the steel sheet in the induction heating device is 0.7 × T 2 seconds or more. Determine the plate passing speed of the previous steel plate passing through the apparatus, and determine the heating output of the induction heating device to be the power input power at which the surface temperature of the previous steel plate does not exceed the allowable temperature at the plate passing speed. To do And it has a feature.

請求項３記載の発明は、請求項１または２記載の発明において、誘導加熱装置は、ソレノイド型であることに特徴を有するものである。   The invention described in claim 3 is characterized in that, in the invention described in claim 1 or 2, the induction heating device is of a solenoid type.

この発明によれば、圧延後または加速冷却後の鋼板の幅方向温度分布を効率的に低減できるため、鋼板の残留応力が小さくなり、条切りキャンバーに代表される鋼板の変形不具合を低減することが可能となる。   According to the present invention, since the temperature distribution in the width direction of the steel sheet after rolling or accelerated cooling can be efficiently reduced, the residual stress of the steel sheet is reduced, and deformation defects of the steel sheet represented by the cut-off camber are reduced. Is possible.

この発明の、鋼板の熱処理方法の一実施形態を、図面を参照しながら説明する。   An embodiment of the steel plate heat treatment method of the present invention will be described with reference to the drawings.

図１は、この発明を適用する厚板鋼板の製造ラインの一例を示す概略斜視図である。   FIG. 1 is a schematic perspective view showing an example of a production line for thick steel plates to which the present invention is applied.

図１において、１は、圧延機、２は、加速冷却装置、３は、ホットレベラ、４は、ソノレイド型誘導加熱装置、そして、５は、加速冷却装置２、ホットレベラ３および誘導加熱装置４のそれぞれの鋼板出側に設置された温度計である。   In FIG. 1, 1 is a rolling mill, 2 is an accelerated cooling device, 3 is a hot leveler, 4 is a sono-red type induction heating device, and 5 is an accelerated cooling device 2, a hot leveler 3 and an induction heating device 4, respectively. It is a thermometer installed on the steel sheet exit side.

圧延機１で圧延された鋼板は、加速冷却装置２により水冷されるか、またはそのまま水冷なしで加速冷却装置２を通過する。続いて、ホットレベラ３で熱間矯正された後、ソノレイド型誘導加熱装置４で加熱される。また、鋼板の板幅方向温度分布は各温度計５によって測定される。   The steel sheet rolled by the rolling mill 1 is cooled with water by the accelerated cooling device 2 or passes through the accelerated cooling device 2 without water cooling. Subsequently, after hot correction with the hot leveler 3, it is heated with the sonolide type induction heating device 4. Further, the temperature distribution in the plate width direction of the steel plate is measured by each thermometer 5.

圧延または加熱冷却後の鋼板は、板幅方向に温度分布を生じており、図２に示すように板幅端部の温度降下が特に大きい。このような温度分布を最小化するため、本発明者等は、ソノレイド型誘導加熱装置を圧延ラインに設置して鋼板を加熱することを検討した。   The steel plate after rolling or heating and cooling has a temperature distribution in the plate width direction, and the temperature drop at the end of the plate width is particularly large as shown in FIG. In order to minimize such a temperature distribution, the present inventors studied to install a sonolide type induction heating device in the rolling line to heat the steel sheet.

鋼板は、圧延後や加速冷却後に誘導加熱装置を通過する時点では、キュリー点以下の温度まで冷却されている場合が多い。このとき、鋼板は強磁性体であるため、ソノレイド型での誘導加熱は鋼板の表面に作用し、表層近傍の薄い部分が加熱されることになる。この特性を利用すると、板幅端部の温度を優先的に上昇させる加熱が可能である。すなわち、鋼板の表面は上下面のみならず側面があるため、板幅端部では側面の加熱作用によって加熱時の温度上昇量が大きい。   Steel plates are often cooled to a temperature below the Curie point when they pass through an induction heating device after rolling or after accelerated cooling. At this time, since the steel plate is a ferromagnetic material, the sonolaid type induction heating acts on the surface of the steel plate, and the thin portion near the surface layer is heated. If this characteristic is utilized, the heating which preferentially raises the temperature of a board width end part is possible. That is, since the surface of the steel sheet has not only the upper and lower surfaces but also side surfaces, the temperature rise during heating is large due to the heating action of the side surfaces at the plate width end.

図３は、解析により求めたソノレイド型誘導加熱装置による加熱前後の板幅方向温度分布であり、加熱により板幅端部の温度上昇が大きいことが分かる。鋼板の残留応力を低減するためには、板幅方向の温度分布を小さくすることが有効であり、この発明は、鋼板の板幅方向温度分布を最小化することが可能な誘導加熱方法である。   FIG. 3 shows the temperature distribution in the plate width direction before and after heating by the sonolide type induction heating apparatus obtained by analysis, and it can be seen that the temperature rise at the plate width end portion is large due to heating. In order to reduce the residual stress of the steel sheet, it is effective to reduce the temperature distribution in the sheet width direction, and the present invention is an induction heating method capable of minimizing the temperature distribution in the sheet width direction of the steel sheet. .

本発明者等は、図３に示す解析や誘導加熱装置を用いた実験を行って、板幅方向温度分布をできるだけ小さくすることができる加熱方法を検討した。   The present inventors conducted an analysis using the analysis shown in FIG. 3 and an experiment using an induction heating apparatus, and examined a heating method that can make the temperature distribution in the plate width direction as small as possible.

この発明によれば、鋼板は、圧延ラインに設置したソノレイド型誘導加熱装置によって加熱され、その後、空冷される。第１発明の加熱方法は、図４のフローチャートに示す通りであり、以下にその内容を説明する。   According to this invention, a steel plate is heated by the sonolide type induction heating apparatus installed in the rolling line, and then air-cooled. The heating method of the first invention is as shown in the flowchart of FIG. 4, and the contents thereof will be described below.

鋼板の加熱において、加熱後の鋼板が変態点以上の温度になると、組織が変化して板厚方向に不均一となるため、誘導加熱装置の出力は、鋼板の表面が変態点以上の温度にならないという制約を設ける必要がある。この条件下で板幅方向の温度分布を最小化する加熱条件を求めなければならない。   When heating the steel sheet, the structure changes and becomes non-uniform in the thickness direction when the heated steel sheet is at a temperature higher than the transformation point. It is necessary to set a constraint that it must not. Under these conditions, a heating condition that minimizes the temperature distribution in the plate width direction must be obtained.

板幅方向の温度差を評価するため、板幅端部から５０ｍｍの位置と板幅中央部との温度差が加熱条件と経過時間によりどのように変化するかを調べた。このとき用いた鋼板の寸法は、板厚２０ｍｍ、板幅２５００ｍｍであった。この結果を図５に示す。なお、ここで板幅端部の温度の代表点を端部から５０ｍｍとした理由は、図３から分かるように、誘導加熱後の温度が最小となるのがこの位置であるためである。図５はコイル内を通過する時間を変化させた３条件で解析を行ったものであり、それぞれの加熱時間で鋼板表面温度が変態点（例えば７２０℃）を超えないよう、加熱装置の出力を調整している。その結果、加熱時間が長いほど、温度差が小さくなっていることが分かる。また、加熱直後よりも時間が経過するほど温度差が小さくなっており、ある時間以上経過するとまた温度差が徐々に広がることが分かる。以上のことから、ソノレイド型誘導加熱装置を用いて板幅方向の温度分布を低減させるためには、低出力の誘導加熱で時間をかけて加熱することが有効であることが分かった。なお、板幅方向温度差は、１０℃以下とすることが望ましい。   In order to evaluate the temperature difference in the plate width direction, it was examined how the temperature difference between the position 50 mm from the end of the plate width and the center portion of the plate width changes depending on heating conditions and elapsed time. The dimensions of the steel plate used at this time were a plate thickness of 20 mm and a plate width of 2500 mm. The result is shown in FIG. Here, the reason why the representative point of the temperature at the end of the plate width is set to 50 mm from the end is that, as can be seen from FIG. 3, the temperature after induction heating is the minimum at this position. FIG. 5 shows an analysis under three conditions in which the time for passing through the coil is changed. The output of the heating device is set so that the surface temperature of the steel sheet does not exceed the transformation point (for example, 720 ° C.) in each heating time. It is adjusted. As a result, it can be seen that the longer the heating time, the smaller the temperature difference. Further, it can be seen that the temperature difference becomes smaller as time elapses than immediately after heating, and the temperature difference gradually widens after a certain period of time. From the above, in order to reduce the temperature distribution in the plate width direction using the sonolide type induction heating apparatus, it has been found that it is effective to perform heating with low output induction heating over time. The temperature difference in the plate width direction is desirably 10 ° C. or less.

ところが、実際の鋼板の製造では、複数枚の鋼板が続けて次々に圧延されるため、加熱時間には制限があり、次の鋼板が加熱装置に到達するまでに加熱を終了しなければならない。先の鋼板の加熱開始時点から、先の鋼板に続いて熱処理される次の鋼板が誘導加熱装置に到達するまでの時間をＴ1秒とすると、Ｔ1は、例えば１５０秒程度であり、この時間Ｔ1秒内に鋼板の加熱を終了させる必要がある。そこで、この発明では板幅方向温度差を１０℃以下とする加熱条件として、先の鋼板の加熱開始時点から、次の鋼板が加熱装置に到達するまでの時間Ｔ1を求め、この時間Ｔ1内で最も長時間の加熱が可能な通板速度を算出することとした。図６は、２０ｍｍ×２５００ｍｍ×２５０００ｍｍの寸法の鋼板について、時間Ｔ1を１８０秒としたときに、誘導加熱での加熱時間と幅方向温度差との関係を調べた結果である。図６から加熱時間が１２６秒以上、すなわち、０．７×Ｔ1秒以上であれば、幅方向温度差が１０℃以下となっている。従って、第１発明では、前記時間Ｔ1の中で、先の鋼板の加熱時間が０．７×Ｔ1秒以上となるように加熱装置を通過する先の鋼板の通板速度を決定する。ここで、鋼板は、その全長に亘ってソレノイド型誘導加熱装置を通過しながら、先端から後端まで順次加熱されるため、通板速度は、鋼板の鋼板長さの影響をも考慮して決定される。なお、時間Ｔ1が短い場合には、０．７×Ｔ1秒で加熱しても幅方向温度差が１０℃以下にならない場合もあり、時間Ｔ1内で最も長時間の加熱となるように時間設定する必要があるが、少なくとも０．７×Ｔ1秒以上であれば、幅方向温度差は許容範囲に縮小される。 However, in actual production of steel plates, since a plurality of steel plates are continuously rolled one after another, the heating time is limited, and heating must be terminated before the next steel plate reaches the heating device. If the time from the start of heating the previous steel plate to the time when the next steel plate to be heat-treated following the previous steel plate reaches the induction heating device is T 1 second, T 1 is about 150 seconds, for example. It is necessary to finish the heating of the steel sheet within time T 1 second. Therefore, as the heating conditions for the plate width direction temperature difference between 10 ° C. or less in the present invention, the heating start time of the previous steel, seek time T 1 of the until the next steel sheet reaches the heating device, the time T 1 It was decided to calculate the plate passing speed capable of heating for the longest time. FIG. 6 shows the result of examining the relationship between the heating time in induction heating and the temperature difference in the width direction when the time T 1 is 180 seconds for a steel plate having dimensions of 20 mm × 2500 mm × 25000 mm. From FIG. 6, when the heating time is 126 seconds or more, that is, 0.7 × T 1 seconds or more, the temperature difference in the width direction is 10 ° C. or less. Thus, in the first invention, wherein in a time T 1, to determine the sheet passing speed of the previous steel sheet passing through the heating device as the heating time of the previous steel sheet becomes 0.7 × T 1 second or more. Here, since the steel plate is sequentially heated from the front end to the rear end while passing through the solenoid induction heating device over its entire length, the plate passing speed is determined in consideration of the influence of the steel plate length of the steel plate. Is done. When the time T 1 is short, the temperature difference in the width direction may not become 10 ° C. or less even if heating is performed at 0.7 × T 1 second, and the heating is performed for the longest time within the time T 1 . However, if it is at least 0.7 × T 1 second or more, the temperature difference in the width direction is reduced to an allowable range.

鋼板の通板速度は、全長にわたって一定速度とする方法が最も容易であるが、図７に示すように鋼板速度を加速または減速させることも可能である。図７では鋼板の加減速は緩やかな変化としているが、より急峻な変化を持たせることも可能であり、加減速を組合わせることもできる。   The method of making the sheet passing speed constant at the entire length is the easiest, but the steel sheet speed can be accelerated or decelerated as shown in FIG. In FIG. 7, the acceleration / deceleration of the steel sheet is a gradual change, but it is also possible to have a steeper change, and the acceleration / deceleration can be combined.

また、誘導加熱装置の投入パワーは、前述のように決定した通板速度で、鋼板表面温度が変態点を超えないという条件で求めることとした。具体的には、例えば、予め投入パワーと加熱時間に対する温度上昇量を求めておき、加熱前の鋼板温度を逆変態しない上限温度から引いた温度差よりも温度上昇量が小さくなるよう、投入パワーを決定する。ただし、温度分布を最小化するためには、鋼板の表面が逆変態する温度未満のできるだけ高い温度とすることが望ましく、加熱温度は逆変態に到達しない制約内で最も高い温度とすべきである。以上の方法によれば、圧延の生産性を阻害することなく、板幅方向の温度分布を最小化することが可能となる。   Moreover, the input power of the induction heating device was determined under the condition that the steel plate surface temperature did not exceed the transformation point at the plate passing speed determined as described above. Specifically, for example, the amount of temperature increase with respect to the input power and heating time is obtained in advance, and the input power is set so that the temperature increase amount is smaller than the temperature difference obtained by subtracting the steel plate temperature before heating from the upper limit temperature that does not reversely transform. To decide. However, in order to minimize the temperature distribution, it is desirable to make the temperature as high as possible below the temperature at which the surface of the steel sheet undergoes reverse transformation, and the heating temperature should be the highest temperature within the constraints that do not reach reverse transformation. . According to the above method, the temperature distribution in the sheet width direction can be minimized without impairing the productivity of rolling.

投入パワーは、鋼板の全長にわたって一定とする方法が最も容易であるが、図８に示すように鋼板の通過位置によって変化させることも可能である。また、鋼板の通板速度が変化する場合には、これに合わせて例えば加速時には投入パワーも大きくするなどの調整をする必要がある。また、図８に示すパターン以外にも、投入パワーにより急峻な変化を持たせることも可能であり、パワーの増減を組合わせることもできる。   The method of making the input power constant over the entire length of the steel plate is the easiest, but it is also possible to change it depending on the passing position of the steel plate as shown in FIG. Further, when the plate passing speed of the steel plate changes, it is necessary to adjust accordingly such as increasing the input power during acceleration. In addition to the pattern shown in FIG. 8, it is also possible to have a steep change depending on the input power, and it is also possible to combine power increase and decrease.

なお、通板速度の決定方法としては、各鋼板の次材との時間余裕に基づいてそれぞれ最大加熱時間を算出して別々の通板速度を決定してもよく、また、次材との時間余裕を複数の鋼板の中で最小のものに合わせて求め、これをもとに最大加熱時間を算出して共通の通板時間を決定してもよい。   In addition, as a method for determining the sheet passing speed, the respective heating speeds may be determined by calculating the maximum heating time based on the time margin with the next material of each steel sheet, and the time with the next material may be determined. The margin may be obtained by matching the smallest one among the plurality of steel plates, and the maximum heating time may be calculated based on this to determine the common plate passing time.

第２発明は、ソノレイド型誘導加熱装置による鋼板の加熱後に、鋼板をホットレベラにより矯正することにより、加熱により鋼板に発生した熱応力を除去し、空冷後の鋼板に内在する残留応力をさらに低減させる技術である。図９に、第２発明の加熱方法のフローチャートを示し、以下にその内容を説明する。   2nd invention removes the thermal stress which generate | occur | produced in the steel plate by heating by correcting a steel plate with a hot leveler after the steel plate is heated by a sonolide type induction heating device, and further reduces the residual stress inherent in the steel plate after air cooling Technology. In FIG. 9, the flowchart of the heating method of 2nd invention is shown, and the content is demonstrated below.

図１の圧延ラインで、第２発明を実施する場合、鋼板は誘導加熱装置を通過後、ホットレベラ前まで一旦逆送され、その後ホットレベラを正方向に通板されて繰り返し曲げの矯正を受ける。ただし、圧延ラインの構成は図１に示す形態に限定されるものではなく、例えば、誘導加熱装置の後に新たなホットレベラを設置した設備を使用してもよく、また、ホットレベラが誘導加熱装置に近接配置されていれば、正方向、逆方向の搬送を組み合わせることにより、この発明の方法が適用できる。   In the rolling line of FIG. 1, when the second invention is carried out, the steel sheet is once fed back to the hot leveler after passing through the induction heating device, and then passed through the hot leveler in the forward direction and repeatedly subjected to bending correction. However, the configuration of the rolling line is not limited to the form shown in FIG. 1. For example, a facility in which a new hot leveler is installed after the induction heating device may be used, and the hot leveler is close to the induction heating device. If arranged, the method of the present invention can be applied by combining forward and reverse conveyances.

第２発明では、鋼板は、圧延ラインに設置したソノレイド型誘導加熱装置によって加熱され、さらにホットレベラで矯正された後に空冷される。第１発明で説明した通り、ソノレイド型誘導加熱装置を用いて板幅方向の温度分布を低減させるためには、低出力の誘導加熱で時間をかけて加熱することが有効である。また、図５より加熱後２００秒程度までであれば、加熱後の時間が長いほど、板幅端部５０ｍｍの位置と板幅中央部との温度差が小さくなる傾向にある。矯正により残留応力を除去するためには、鋼板幅方向の温度差が小さいことが必要であるため、加熱後２００秒以内に矯正することが望ましい。   In the second invention, the steel sheet is heated by a sonolide type induction heating device installed in the rolling line, further corrected by a hot leveler, and then air-cooled. As described in the first aspect of the invention, in order to reduce the temperature distribution in the plate width direction using the sonolide type induction heating apparatus, it is effective to perform heating with low output induction heating over time. Further, from FIG. 5, if the time is up to about 200 seconds after heating, the longer the time after heating, the smaller the temperature difference between the position of the plate width end portion 50 mm and the center portion of the plate width. In order to remove the residual stress by straightening, it is necessary that the temperature difference in the width direction of the steel sheet is small, so it is desirable to straighten within 200 seconds after heating.

以上のことから、誘導加熱後にホットレベラ矯正を行う場合であっても、第１発明と同様に、誘導加熱装置により熱処理される先の鋼板の加熱開始時点から、次の鋼板が加熱装置に到達するまでの時間の中で、できるだけ長い時間をかけて加熱することが、板幅方向の温度分布低減のために最善であることが分かった。このとき、第１発明と異なりホットレベラ通過のための時間が必要となることから、これから加熱しようとする鋼板の加熱開始時点から、次の鋼板が加熱装置に到達するまでの時間から、加熱後にホットレベラを通過する時間を差し引いた時間が加熱を行うための最大時間ということになる。   From the above, even when hot leveler correction is performed after induction heating, the next steel sheet reaches the heating device from the start of heating the previous steel plate heat-treated by the induction heating device, as in the first invention. It was found that heating for as long a time as possible during the time period up to is the best for reducing the temperature distribution in the plate width direction. At this time, unlike the first invention, time for passing through the hot leveler is required, so from the time when the steel plate to be heated is heated until the next steel plate reaches the heating device, the hot leveler is heated after heating. The time obtained by subtracting the time for passing through is the maximum time for heating.

すなわち、第２発明では、誘導加熱装置により熱処理される先の鋼板の加熱開始時点から、先の鋼板に続いて熱処理される次の鋼板が誘導加熱装置に到達するまでの時間をＴ1秒とし、Ｔ1秒からホットレベラを通過するのに必要な時間を差し引いた時間をＴ2秒としたときに、先の鋼板の加熱時間が０．７×Ｔ2秒以上となるように、誘導加熱装置を通過する先の鋼板の通板速度を決定する。加熱時間を０．７×Ｔ2秒以上としたのは、第１発明と同様に、加熱時間が０．７×Ｔ2秒未満では、板幅方向温度差が許容範囲まで低減されないからである。 That is, in the second invention, the time from the start of heating the previous steel plate heat-treated by the induction heating device to the time when the next steel plate to be heat-treated following the previous steel plate reaches the induction heating device is T 1 second. Induction heating device so that the heating time of the previous steel sheet is 0.7 × T 2 seconds or more when the time obtained by subtracting the time required to pass the hot leveler from T 1 second is T 2 seconds The plate passing speed of the steel plate that passes through is determined. The reason why the heating time is set to 0.7 × T 2 seconds or more is that, similarly to the first invention, when the heating time is less than 0.7 × T 2 seconds, the temperature difference in the plate width direction is not reduced to the allowable range. .

図１の圧延ラインを用いて具体的に説明すると、鋼板はホットレベラから正方向に通板されて誘導加熱装置に進入して加熱され、加熱後に逆方向に搬送されてホットレベラ前まで戻され、さらに正方向にホットレベラを通過して矯正される。従って、加熱後の逆方向、正方向の通板に要する時間がホットレベラ通過のために必要な時間となる。   Specifically, using the rolling line of FIG. 1, the steel plate is passed through the hot leveler in the forward direction, enters the induction heating device, is heated, is transported in the reverse direction after heating, and is returned to before the hot leveler. It is corrected through the hot leveler in the positive direction. Therefore, the time required for passing the plate in the reverse direction and the forward direction after heating is the time required for passing through the hot leveler.

以上のようにして加熱に使用できる時間Ｔ2を求め、板幅方向温度差が最小化する０．７×Ｔ2秒以上の加熱時間で鋼板が加熱装置を通過する搬送速度を加熱時の搬送速度として設定する。さらに、鋼板を加熱するための誘導加熱装置の電力投入パワーは、決定した鋼板の搬送速度において、鋼板の表面が逆変態する温度以下となるよう決定する。ただし、温度分布を最小化するためには、鋼板の表面が逆変態する温度未満のできるだけ高い温度とすることが望ましく、加熱温度は逆変態に到達しない制約内で最も高い温度とすべきである。以上の方法によれば、圧延の生産性を阻害することなく、鋼板の幅方向温度差を最小化することが可能となる。 The time T 2 that can be used for heating is obtained as described above, and the conveyance speed at which the steel sheet passes through the heating device is heated at a heating time of 0.7 × T 2 seconds or more that minimizes the temperature difference in the sheet width direction. Set as speed. Furthermore, the power input power of the induction heating device for heating the steel sheet is determined so as to be equal to or lower than the temperature at which the surface of the steel sheet undergoes reverse transformation at the determined steel sheet conveyance speed. However, in order to minimize the temperature distribution, it is desirable to make the temperature as high as possible below the temperature at which the surface of the steel sheet undergoes reverse transformation, and the heating temperature should be the highest temperature within the constraints that do not reach reverse transformation. . According to the above method, it is possible to minimize the temperature difference in the width direction of the steel sheet without impairing the productivity of rolling.

この発明の実施例として、ソノレイド型誘導加熱装置を用いて板幅方向での温度差を最小化する具体例を説明する。   As an embodiment of the present invention, a specific example of minimizing a temperature difference in the plate width direction using a sono-red type induction heating apparatus will be described.

図１に示す設備を用いて第１発明の方法を実施した。すなわち、圧延機１により圧延後、加速冷却装置２で冷却した、寸法２０ｍｍ×２５００ｍｍ×２５０００ｍｍの鋼板をホットレベラ３で熱間矯正し、この後、ソノレイド型誘導加熱装置４で加熱した。ここで、誘導加熱装置による先の鋼板の加熱開始時点から、次の鋼板が加熱装置に到達するまでの時間は１２０秒であった。加熱前の鋼板の板幅方向での温度分布は、板幅端部から５０ｍｍの位置の温度が板幅中央部に対し３１℃低かった。また、この鋼板の長さは２５ｍであり、誘導加熱装置４の長さは５ｍであることから、加熱開始から終了まで、鋼板は３０ｍ移動する必要があった。以上のことから鋼板の誘導加熱装置通板速度を１５ｍ／分の一定速度とし、８４秒（１２０秒×０．７）で鋼板の先端から尾端までの加熱が終了するようにした。加熱装置の電力投入パワーは約１２ＭＷで一定とし、鋼板の表裏面が逆変態を開始する温度である７２０℃を超えず、約７１０℃となるよう決定した。なお、鋼板の端部は後工程で切り捨てられることから、７２０℃を超えても問題はなく、温度上限の規制は鋼板表裏面に限定した。   The method of 1st invention was implemented using the installation shown in FIG. That is, after rolling by the rolling mill 1, a steel plate having a size of 20 mm × 2500 mm × 25000 mm cooled by the accelerated cooling device 2 was hot-corrected by the hot leveler 3 and then heated by the sonolide type induction heating device 4. Here, the time from the start of heating the previous steel plate by the induction heating device to the arrival of the next steel plate at the heating device was 120 seconds. Regarding the temperature distribution in the plate width direction of the steel plate before heating, the temperature at a position of 50 mm from the plate width end was 31 ° C. lower than the plate width central portion. Moreover, since the length of this steel plate is 25 m and the length of the induction heating apparatus 4 is 5 m, it was necessary to move the steel plate by 30 m from the start to the end of heating. From the above, the sheet heating speed of the induction heating apparatus of the steel sheet was set to a constant speed of 15 m / min, and heating from the front end to the tail end of the steel sheet was completed in 84 seconds (120 seconds × 0.7). The power input power of the heating device was fixed at about 12 MW, and was determined to be about 710 ° C., not exceeding 720 ° C., which is the temperature at which the front and back surfaces of the steel sheet started reverse transformation. In addition, since the edge part of a steel plate is cut off by a post process, even if it exceeded 720 degreeC, there was no problem and the restriction | limiting of the upper limit of temperature was limited to the steel plate front and back.

以上の条件で加熱を行った結果、板幅端部から５０ｍｍの位置と板幅中央部の温度差は加熱後１２０秒の時点で９℃まで小さくなった。この鋼板を冷却後、幅１５０ｍｍで条切りした結果、長さ１０ｍでの条材のキャンバーは５ｍｍと小さな値であった。   As a result of heating under the above conditions, the temperature difference between the position 50 mm from the end of the plate width and the center of the plate width was reduced to 9 ° C. at 120 seconds after heating. After cooling this steel plate, it was cut at a width of 150 mm. As a result, the camber of the strip at a length of 10 m was a small value of 5 mm.

これに対し、比較例として同じ寸法と温度分布の鋼板を、加熱時間を短縮する目的で通板速度を６０ｍ／分の一定速度として誘導加熱装置で加熱した。通過時間は３０秒であった。加熱装置の電力投入パワーは、この場合にも鋼板表面が７１０℃となるように決定し、２２ＭＷとした。このとき、加熱後１２０秒の時点で板幅端部から５０ｍｍの位置と板幅中央部の温度差は２１℃と加熱の効果が少なく、温度分布低減が不十分であった。また、この鋼板を冷却後、幅１５０ｍｍで条切りした結果、長さ１０ｍでの条材のキャンバーは１２ｍｍであり、本発明の場合に比べ、２倍以上のキャンバーが発生した。   On the other hand, as a comparative example, a steel plate having the same size and temperature distribution was heated with an induction heating device at a constant speed of 60 m / min for the purpose of shortening the heating time. The transit time was 30 seconds. The power input power of the heating device was determined so that the steel plate surface was 710 ° C. in this case as well, and was set to 22 MW. At this time, at 120 seconds after heating, the temperature difference between the position 50 mm from the end of the plate width and the center of the plate width was 21 ° C., and the heating effect was small, and the temperature distribution was not sufficiently reduced. In addition, as a result of cooling this steel plate after cutting it at a width of 150 mm, the camber of the strip material at a length of 10 m was 12 mm, and a camber more than twice as large as that of the present invention was generated.

次に、誘導加熱装置とホットレベラを用いて鋼板の残留応力を低減させる第２発明の実施例を説明する。   Next, an embodiment of the second invention for reducing the residual stress of the steel sheet using an induction heating device and a hot leveler will be described.

図１に示す設備を用いて第２発明の方法を実施した。圧延機１により圧延後、加速冷却装置２で冷却した、寸法２０ｍｍ×２５００ｍｍ×２５０００ｍｍの鋼板をホットレベラ３で熱間矯正し、この後、ソノレイド型誘導加熱装置４で加熱した。加熱後、ホットレベラ３の前まで鋼板を逆方向に搬送した後、ホットレベラ３で矯正を行った。ここで、誘導加熱装置４による先の鋼板の加熱開始時点から、次の鋼板が加熱装置に到達するまでの時間は１５０秒であった。加熱前の鋼板の板幅方向での温度分布は、板幅端部から５０ｍｍの位置の温度が板幅中央部に対し３１℃低かった。また、この鋼板の長さは２５ｍであり、誘導加熱装置４の長さは５ｍであることから、加熱開始から終了まで、鋼板は３０ｍ移動する必要があった。また、ホットレベラ入口と加熱装置入口の距離は１５ｍであった。鋼板のホットレベラ通過時間は、通板速度が通常９０ｍ／分であることから、逆送の１パスと正方向の１パスの２パスで合計６０秒の時間が必要であった。従って、可能な加熱時間は９０秒であった。以上のことから、鋼板の誘導加熱装置通板速度を約２０ｍ／分の一定速度とし、６３秒（９０秒×０．７）で鋼板の先端から尾端までの加熱終了するようにした。加熱装置の電力投入パワーは１５ＭＷで一定とし、鋼板の表裏面が逆変態を開始する温度である７２０℃を超えず、約７１０℃となるよう決定した。   The method of 2nd invention was implemented using the installation shown in FIG. After rolling by the rolling mill 1, a steel plate having a size of 20 mm × 2500 mm × 25000 mm cooled by the acceleration cooling device 2 was hot-corrected by the hot leveler 3 and then heated by the sonolide type induction heating device 4. After the heating, the steel plate was conveyed in the reverse direction before the hot leveler 3, and then corrected with the hot leveler 3. Here, the time from the start of heating the previous steel plate by the induction heating device 4 until the next steel plate reaches the heating device was 150 seconds. Regarding the temperature distribution in the plate width direction of the steel plate before heating, the temperature at a position of 50 mm from the plate width end was 31 ° C. lower than the plate width central portion. Moreover, since the length of this steel plate is 25 m and the length of the induction heating apparatus 4 is 5 m, it was necessary to move the steel plate by 30 m from the start to the end of heating. The distance between the hot leveler inlet and the heating device inlet was 15 m. Since the plate passing speed is usually 90 m / min, the time required for the steel plate to pass through the hot leveler is 60 seconds in total for two passes, one pass in the reverse direction and one pass in the forward direction. Therefore, the possible heating time was 90 seconds. From the above, the induction plate passing speed of the steel sheet was set to a constant speed of about 20 m / min, and heating from the front end to the tail end of the steel sheet was completed in 63 seconds (90 seconds × 0.7). The power input power of the heating device was fixed at 15 MW, and it was determined that the front and back surfaces of the steel sheet did not exceed 720 ° C., which is the temperature at which reverse transformation starts, and was about 710 ° C.

以上の条件で鋼板を加熱した結果、鋼板の板幅端部から５０ｍｍの位置と板幅中央の温度差はホットレベラ直前で１５℃まで低減した。また、この鋼板をホットレベラで矯正した後、冷却し、幅１５０ｍｍで条切りしたところ、長さ１０ｍでの条材のキャンバーは３ｍｍであり、非常に小さな値となった。   As a result of heating the steel plate under the above conditions, the temperature difference between the position 50 mm from the plate width end of the steel plate and the center of the plate width was reduced to 15 ° C. just before the hot leveler. Moreover, after correcting this steel plate with a hot leveler, it was cooled and cut with a width of 150 mm, and the camber of the strip with a length of 10 m was 3 mm, which was a very small value.

一方、比較例として同じ寸法と温度分布の鋼板を、加熱時間を短縮する目的で通板速度を６０ｍ／分の一定速度として誘導加熱装置で加熱した。通過時間は３０秒であった。続いて、９０ｍ／分の通板速度で逆送した後、正方向に通板してホットレベラ３で矯正を行った。その結果、加熱後、ホットレベラを通過する直前の鋼板の温度分布は板幅端部から５０ｍｍと板幅中央での温度差が２３℃であった。この鋼板をホットレベラで矯正後、冷却し、幅１５０ｍｍで条切りしたところ、長さ１０ｍでの条材のキャンバーは７ｍｍであり、本発明の方法の遅い通板速度で加熱を行った場合に比べ、キャンバー量が大きく、効果が不十分であった。   On the other hand, a steel plate having the same size and temperature distribution as a comparative example was heated with an induction heating device at a constant plate feed speed of 60 m / min for the purpose of shortening the heating time. The transit time was 30 seconds. Subsequently, after reverse feeding at a plate passing speed of 90 m / min, the plate was passed in the forward direction and corrected with the hot leveler 3. As a result, after heating, the temperature distribution of the steel plate immediately before passing through the hot leveler was 50 mm from the plate width end, and the temperature difference at the plate width center was 23 ° C. When this steel plate was straightened with a hot leveler, cooled, and cut with a width of 150 mm, the length of the 10 m long camber was 7 mm, compared with the case where heating was performed at the slow plate speed of the method of the present invention. The camber amount was large and the effect was insufficient.

この発明を適用する厚板鋼板の製造ラインの一例を示す概略斜視図である。It is a schematic perspective view which shows an example of the production line of the thick steel plate to which this invention is applied. 圧延または加速冷却後の鋼板の板幅方向での温度分布を示すグラフである。It is a graph which shows the temperature distribution in the plate width direction of the steel plate after rolling or accelerated cooling. 誘導加熱装置による加熱前後の鋼板温度分布を示すグラフである。It is a graph which shows the steel plate temperature distribution before and behind the heating by an induction heating apparatus. 第１発明による加熱方法を示すフローチャートである。It is a flowchart which shows the heating method by 1st invention. 加熱開始からの経過時間と温度差との関係を示すグラフである。It is a graph which shows the relationship between the elapsed time from a heating start, and a temperature difference. 加熱時間と板幅方向温度差との関係を示すグラフである。It is a graph which shows the relationship between a heating time and a board width direction temperature difference. 通板時間と通板速度との関係を示すグラフである。It is a graph which shows the relationship between boarding time and boarding speed. 通板時間と投入パワーとの関係を示すグラフである。It is a graph which shows the relationship between boarding time and throwing power. 第２発明による加熱方法を示すフローチャートである。It is a flowchart which shows the heating method by 2nd invention.

符号の説明Explanation of symbols

１：圧延機
２：加速冷却装置
３：ホットレベラ
４：誘導加熱装置
５：温度計 1: Rolling mill 2: Accelerated cooling device 3: Hot leveler 4: Induction heating device 5: Thermometer

Claims (3)

圧延または加速冷却後の鋼板を、圧延ライン上に配置した誘導加熱装置を用いて加熱する鋼板の熱処理方法において、
前記誘導加熱装置により熱処理される先の鋼板の加熱開始時点から、前記先の鋼板に続いて熱処理される次の鋼板が前記誘導加熱装置に到達するまでの時間をＴ1秒としたときに、前記先の鋼板の前記誘導加熱装置での加熱時間が０．７×Ｔ1秒以上となるように、前記誘導加熱装置を通過する前記先の鋼板の通板速度を決定し、前記誘導加熱装置の加熱出力は、前記通板速度において前記先の鋼板の表面温度が許容温度を超えない電力投入パワーとなるよう決定することを特徴とする、鋼板の熱処理方法。 In the heat treatment method of the steel sheet, the steel sheet after rolling or accelerated cooling is heated using an induction heating device arranged on the rolling line.
When the time until the next steel plate to be heat-treated following the previous steel plate reaches the induction heating device from the start of heating the previous steel plate to be heat-treated by the induction heating device is T 1 second, Determining the sheet passing speed of the previous steel plate passing through the induction heating device such that the heating time of the previous steel plate in the induction heating device is 0.7 × T 1 second or more, and the induction heating device The heating output of is determined such that the surface temperature of the steel plate becomes a power input power that does not exceed an allowable temperature at the plate passing speed. 圧延または加速冷却後の鋼板を、圧延ライン上に配置した誘導加熱装置を用いて加熱した後、ホットレベラにより熱間矯正する、鋼板の熱処理方法において、
前記誘導加熱装置により熱処理される先の鋼板の加熱開始時点から、前記先の鋼板に続いて熱処理される次の鋼板が前記誘導加熱装置に到達するまでの時間をＴ1秒とし、Ｔ1秒から前記ホットレベラを通過するのに必要な時間を差し引いた時間をＴ2秒としたときに、前記先の鋼板の前記誘導加熱装置での加熱時間が０．７×Ｔ2秒以上となるように、前記誘導加熱装置を通過する前記先の鋼板の通板速度を決定し、前記誘導加熱装置の加熱出力は、前記通板速度において前記先の鋼板の表面温度が許容温度を超えない電力投入パワーとなるよう決定することを特徴とする、鋼板の熱処理方法。 In the heat treatment method of the steel sheet, the steel sheet after rolling or accelerated cooling is heated using an induction heating device arranged on a rolling line and then hot-corrected by a hot leveler.
The time from the start of heating of the previous steel plate heat-treated by the induction heating device to the time when the next steel plate to be heat-treated following the previous steel plate reaches the induction heating device is defined as T 1 second, and T 1 second. When the time obtained by subtracting the time required to pass through the hot leveler is T 2 seconds, the heating time of the steel sheet in the induction heating device is 0.7 × T 2 seconds or more. Determining the plate passing speed of the previous steel plate passing through the induction heating device, and the heating output of the induction heating device is a power input power at which the surface temperature of the previous steel plate does not exceed an allowable temperature at the plate passing speed. A heat treatment method for a steel sheet, characterized in that it is determined to be 前記誘導加熱装置は、ソレノイド型であることを特徴とする、請求項１または２記載の、鋼板の熱処理方法。   The steel plate heat treatment method according to claim 1 or 2, wherein the induction heating device is a solenoid type.
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KR102088688B1 (en) * 2018-09-14 2020-03-13 한국전력공사 Rotor bending correction method using low frequency induction heat and rotor bending correction apparatus using the same
CN115354141A (en) * 2022-08-09 2022-11-18 首钢智新迁安电磁材料有限公司 Heating furnace power control method and device, electronic equipment and medium

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102088688B1 (en) * 2018-09-14 2020-03-13 한국전력공사 Rotor bending correction method using low frequency induction heat and rotor bending correction apparatus using the same
WO2020054935A1 (en) * 2018-09-14 2020-03-19 한국전력공사 Bent rotor straightening method using low frequency induction heating and bent rotor straightening apparatus using same
US11465187B2 (en) 2018-09-14 2022-10-11 Korea Electric Power Corporation Bent rotor straightening method using low frequency induction heating and bent rotor straightening apparatus using same
CN115354141A (en) * 2022-08-09 2022-11-18 首钢智新迁安电磁材料有限公司 Heating furnace power control method and device, electronic equipment and medium
CN115354141B (en) * 2022-08-09 2023-10-20 首钢智新迁安电磁材料有限公司 Heating furnace power control method and device, electronic equipment and medium

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