JP2014065077A5

JP2014065077A5 -

Info

Publication number: JP2014065077A5
Application number: JP2013179000A
Authority: JP
Filing date: 2013-08-30
Publication date: 2016-03-17
Anticipated expiration: 2033-08-30

Description

さらに、本発明の熱間圧延鋼板の製造方法の第３の態様（参考態様）は、
熱間圧延鋼板を熱間圧延機で熱間圧延した後に、これをホットランテーブル上で冷却し、コイラーで巻き取ってコイル状熱間圧延鋼板を製造するに際し、
前記熱間圧延鋼板を、熱間圧延機からホットランテーブル上に加速しながら送り出し、
その送り出し速度の最低速度と最高速度とに対しそれぞれ、コイラーでの巻取時点で前記熱間圧延鋼板の相変態率が１０％以下となるようにホットランテーブル上での中間温度目標および／またはコイラーでの巻取温度目標を設定し、それら温度目標に基づき前記熱間圧延鋼板をその送り出し速度に応じてホットランテーブル上で冷却することを特徴としている。 Furthermore, the 3rd aspect (reference aspect) of the manufacturing method of the hot rolled steel plate of this invention is as follows.
After hot rolling the hot rolled steel sheet with a hot rolling machine, cooling it on a hot run table and winding it with a coiler to produce a coiled hot rolled steel sheet,
Sending out the hot rolled steel sheet while accelerating from a hot rolling mill onto a hot run table,
The intermediate temperature target on the hot run table and / or the coiler so that the phase transformation rate of the hot-rolled steel sheet is 10% or less at the time of winding with the coiler with respect to the minimum speed and the maximum speed of the feeding speed, respectively. The hot rolling steel sheet is cooled on a hot run table in accordance with the feed speed based on the temperature target.

さらに、本発明の熱間圧延鋼板の製造方法の第３の態様（参考態様：変態率低下方法）にあっては、熱間圧延鋼板を、熱間圧延機からホットランテーブル上に加速しながら送り出し、その送り出し速度の最低速度と最高速度とに対しそれぞれ、コイラーでの巻取時点で前記熱間圧延鋼板の相変態率が１０％以下となるようにホットランテーブル上での中間温度目標および／またはコイラーでの巻取温度目標を設定し、それらの温度目標に基づき前記熱間圧延鋼板をその送り出し速度に応じてホットランテーブル上で冷却することから、コイラーでの巻取時点で熱間圧延鋼板の相変態率がその全長に亘り１０％以下となって、巻取後に熱間圧延鋼板がその全長に亘り相変態することになる。 Furthermore, in the third aspect ( reference aspect: transformation rate reduction method) of the method for producing a hot-rolled steel sheet of the present invention, the hot-rolled steel sheet is fed out from a hot rolling mill while being accelerated onto a hot run table. The intermediate temperature target on the hot run table and / or so that the phase transformation rate of the hot-rolled steel sheet is 10% or less at the time of winding with a coiler with respect to the minimum speed and the maximum speed of the feeding speed, respectively. Since the coiling temperature target in the coiler is set and the hot-rolled steel sheet is cooled on the hot run table according to the feed rate based on the temperature target, the hot-rolled steel sheet is The phase transformation rate becomes 10% or less over the entire length, and the hot-rolled steel sheet undergoes phase transformation over the entire length after winding.

従って、この第３の態様（参考態様）によれば、コイラーでの巻取後にコイラー内でコイル状熱間圧延鋼板のコイル外周部とコイル内周部とにおいてそれぞれ相変態が進行してほぼ等しい量の体積膨張が生じ、その際、コイルの外周側では内周側よりも周長が長いためその体積膨張量が周方向長さの増加に使われるので厚さの増加が少なくなる。その結果、コイル外周部に対するコイル内周側の相対的な厚さの増加によって、半径方向の面圧減少によるコイルの緩みが抑制されることから、コイラー内でのコイルつぶれの発生を抑制して生産性を向上させることができる。 Therefore, according to the third aspect (reference aspect) , the phase transformation proceeds in the coil outer periphery and the coil inner periphery of the coiled hot-rolled steel sheet in the coiler after winding with the coiler. In this case, since the outer peripheral side of the coil has a longer peripheral length than the inner peripheral side, the volume expansion amount is used to increase the circumferential length, so that the increase in thickness is reduced. As a result, the increase in the relative thickness of the coil inner periphery with respect to the coil outer periphery suppresses the loosening of the coil due to the reduction of the radial surface pressure, thereby suppressing the occurrence of coil collapse in the coiler. Productivity can be improved.

本発明の熱間圧延鋼板の製造方法の、参考態様を含む上記第1〜第３の態様は何れも特に、Ｃ：０．２５質量％以下（０質量％を含まず）、Ｍｎ：１．５質量％〜２．７質量％およびＳｉ：１．５質量％以下（０質量％を含まず）を添加した熱間圧延鋼板の製造の際に効果的である。 In the method for producing a hot-rolled steel sheet according to the present invention, the first to third aspects including the reference aspect are all particularly C: 0.25% by mass or less (not including 0% by mass), Mn: 1. This is effective when manufacturing a hot-rolled steel sheet to which 5% by mass to 2.7% by mass and Si: 1.5% by mass or less (not including 0% by mass) are added.

通常の熱間圧延ラインの概略を示す構成図である。It is a block diagram which shows the outline of a normal hot rolling line. 中炭素鋼および中炭素・高Ｍｎ鋼の相変態を例示する関係線図である。It is a relationship diagram which illustrates the phase transformation of medium carbon steel and medium carbon and high Mn steel. 低炭素鋼の仕上圧延後経過時間と温度と相変態率（％）との関係を例示するＴＴＴ線図である。It is a TTT diagram which illustrates the relationship between the elapsed time after finish rolling of low carbon steel, temperature, and phase transformation rate (%). 本発明の熱間圧延鋼板の製造方法の実施例を適用する、図１に示す熱間圧延ラインのホットラン冷却設備を示す構成図である。It is a block diagram which shows the hot run cooling equipment of the hot rolling line shown in FIG. 1 to which the Example of the manufacturing method of the hot rolled steel plate of this invention is applied. 本発明の熱間圧延鋼板の製造方法の、参考態様を含む三つの態様における熱間圧延鋼板の先端部（TOP）と尾端部（BOT）の相変態率およびそれらの差を示す関係線図である。The relationship diagram which shows the phase transformation rate of the front-end | tip part (TOP) and tail end part (BOT) of a hot-rolled steel plate in three aspects including the reference aspect of the manufacturing method of the hot-rolled steel sheet of this invention, and those differences It is. 参考態様を含む上記三つの態様のうち圧延速度一定の態様を示す概念図であり、（ａ）は圧延速度一定の状態、（ｂ）は冷却速度一定の状態、（ｃ）は冷却温度一定の状態をそれぞれ熱間圧延鋼板の先端部（TOP）から尾端部（BOT）まで示す。It is a conceptual diagram which shows the aspect with a fixed rolling speed among the said three aspects including a reference aspect , (a) is a state with a constant rolling speed, (b) is a state with a constant cooling speed, (c) is with a constant cooling temperature. The state is shown from the front end (TOP) to the tail end (BOT) of each hot-rolled steel sheet. 参考態様を含む上記三つの態様のうち冷却速度一定の態様を示す概念図であり、（ａ）は圧延速度加速の状態、（ｂ）は冷却速度一定の状態、（ｃ）は冷却温度量増加の状態をそれぞれ熱間圧延鋼板の先端部（TOP）から尾端部（BOT）まで示す。It is a conceptual diagram which shows a mode with constant cooling rate among the above-mentioned three modes including a reference mode , (a) is a state of rolling speed acceleration, (b) is a state with constant cooling rate, (c) is a cooling temperature amount increase. The state of each is shown from the front-end | tip part (TOP) of a hot-rolled steel plate to a tail end part (BOT).

以下、この発明の実施の形態を、図面に基づき詳細に説明する。ここに、図４は、この発明の熱間圧延鋼板の製造方法の、参考態様を含む上記三つの態様のそれぞれの一実施形態を適用する通常の熱間圧延ラインの概略を示す構成図であり、ここにおける熱間圧延ラインでも、加熱炉１において所定温度に加熱したスラブを粗圧延機２で圧延して粗バーとなし、ついでこの粗バーを複数基の圧延スタンドからなる連続熱間仕上圧延機３において所定の厚みの熱間圧延（熱延）鋼板４とする。そして、この熱延鋼板４を、ホットランテーブル（ＨＲＴ）に設置した冷却装置５で上方および下方から供給する冷却水によって冷却した後、張力を付与しながらコイラー６で巻き取り、コイル状熱延鋼板（コイル）７とする。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 4 is a block diagram showing an outline of a normal hot rolling line to which one embodiment of each of the above three aspects including the reference aspect of the method for producing a hot rolled steel sheet of the present invention is applied. Also in the hot rolling line here, the slab heated to a predetermined temperature in the heating furnace 1 is rolled with a roughing mill 2 to form a rough bar, and then this hot bar is continuously hot finished by a plurality of rolling stands. In the machine 3, a hot rolled (hot rolled) steel plate 4 having a predetermined thickness is obtained. And after cooling this hot-rolled steel plate 4 with the cooling water supplied from the upper direction and the downward direction with the cooling device 5 installed in the hot run table (HRT), it winds up with the coiler 6, providing a tension | tensile_strength, and coil-shaped hot-rolled steel plate (Coil) 7.

ところで、コイルつぶれの発生が確認されている鋼の添加元素とは、Ｃ：０．２５質量％以下（０質量％を含まず）、Ｍｎ：１．５質量％〜２．７質量％、Ｓｉ：１．５質量％以下（０質量％を含まず）であり、特に、Ｍｎを１．５質量％以上と多量に添加している。これらは他の鋼種に比べて相変態の進行が遅く、コイルつぶれが発生しやすい条件となっている。このため、本発明の熱間圧延鋼板の製造方法の三つの態様Ｐ１，Ｐ２，Ｐ３（参考態様）は、上記の鋼種に適用する。なお、図２，３に例示するように、相変態温度と目標加工温度とは材料によって異なるので、材料に応じてこれら三つの態様を使い分けると好ましい。 By the way, the additive element of steel in which the occurrence of coil crushing has been confirmed is: C: 0.25% by mass or less (excluding 0% by mass), Mn: 1.5% by mass to 2.7% by mass, Si : 1.5% by mass or less (excluding 0% by mass), and in particular, Mn is added in a large amount of 1.5% by mass or more. These are the conditions in which the progress of phase transformation is slow compared to other steel types and coil collapse is likely to occur. For this reason, three aspects P1, P2, and P3 (reference aspect) of the manufacturing method of the hot-rolled steel sheet of this invention are applied to said steel type. As illustrated in FIGS. 2 and 3, the phase transformation temperature and the target processing temperature differ depending on the material, so it is preferable to use these three modes properly depending on the material.

図５は、コイラー６内でのコイル７の外周部の相変態率を内周部の相変態率と同程度とするための本発明の熱間圧延鋼板の製造方法の三つの態様Ｐ１，Ｐ２，Ｐ３における熱間圧延鋼板の先端部（TOP）と尾端部（BOT）の相変態率およびそれらの差を示す関係線図であり、また、以下の表１は、上記三つの態様Ｐ１，Ｐ２，Ｐ３（参考態様）の内容をそれぞれ示すものである。 FIG. 5 shows three modes P1 and P2 of the method for producing a hot-rolled steel sheet according to the present invention for making the phase transformation rate of the outer peripheral portion of the coil 7 in the coiler 6 the same as the phase transformation rate of the inner peripheral portion. , P3 is a relationship diagram showing the phase transformation rates of the front end portion (TOP) and the tail end portion (BOT) of the hot-rolled steel sheet and the difference between them, and Table 1 below shows the three modes P1, The contents of P2 and P3 (reference modes) are shown respectively.

そして、図５および表１に示すように本発明の第３の態様Ｐ３（参考態様）は、熱間圧延鋼板４の全体の相変態率を減少させることで、コイラー６内でのコイル７の外周部の相変態率を内周部の相変態率と同程度とするものであり、そのために冷却温度の高温化を図っている。 As shown in FIG. 5 and Table 1, the third aspect P3 (reference aspect) of the present invention reduces the overall phase transformation rate of the hot-rolled steel sheet 4, thereby reducing the coil 7 in the coiler 6. The phase transformation rate at the outer peripheral portion is set to the same level as the phase transformation rate at the inner peripheral portion, and for this purpose, the cooling temperature is increased.

このホットラン冷却設備を用い、その冷却装置５の作動条件（熱延鋼板４に供給する冷却水の温度や水量等）を制御することにより、以下の実施例１，２および参考例の製造方法でそれぞれ熱延鋼板を製造した。実施例１の製造方法は、上記第１の態様Ｐ１を実施するものであり、この実施例１は、適用材を、Ｃ：０．１５質量％、Ｍｎ：２．０質量％、その他の元素は相変態挙動に影響を与えない程度の微小量である高Ｍｎ中炭素鋼種で板厚２．９ｍｍの熱延鋼板とし、適用設備／適用工程／適用作業を、仕上圧延速度一定、仕上圧延加速率０．０ｍｐｍ／ｓｅｃ．、ＨＲＴ上での冷却装置５の冷却制御も一定とし、操業条件／加工条件を、仕上出側温度８７０℃、巻取温度６００℃としている。 By using this hot-run cooling equipment and controlling the operating conditions of the cooling device 5 (temperature, amount of cooling water supplied to the hot-rolled steel sheet 4, etc.), the manufacturing methods of Examples 1 and 2 and Reference Examples below are used. Hot rolled steel sheets were produced respectively. The manufacturing method of Example 1 implements said 1st aspect P1, and this Example 1 is C: 0.15 mass%, Mn: 2.0 mass%, and other elements. Is a high-Mn medium carbon steel grade with a thickness of 2.9 mm, which is a minute amount that does not affect the phase transformation behavior, and the applied equipment / application process / application operations are constant at the finish rolling speed and accelerated finish rolling. Rate 0.0 mpm / sec. The cooling control of the cooling device 5 on the HRT is also constant, and the operating / processing conditions are a finishing side temperature of 870 ° C. and a winding temperature of 600 ° C.

また、実施例２の製造方法は、上記第２の態様Ｐ２を実施するものであり、この実施例２は、操業条件のみ実施例１と異なり、仕上圧延加速率１５ｍｐｍ／ｓｅｃ．としている。そして参考例の製造方法は、上記第３の態様Ｐ３を実施するものであり、この参考例は、適用材を、Ｃ：０．００５質量％以下、Ｍｎ：２．０質量％、その他の元素は相変態挙動に影響を与えない程度の微小量である高Ｍｎ低炭素鋼種で板厚３．２ｍｍの熱延鋼板とし、適用設備／適用工程／適用作業を、仕上圧延加速率８．０ｍｐｍ／ｓｅｃ．とし、操業条件／加工条件を、仕上出側温度８９０℃、巻取温度６４０℃としている。なお、コイル内径は７５０ｍｍ、相変態率は変態率計１１で測定した結果、実施例１では熱延鋼板４の全長に亘り６０％±１０％以内、実施例２では熱延鋼板４の全長に亘り１００％−１０％以内、参考例では熱延鋼板４の全長に亘り０％＋１０％以内であった。 Moreover, the manufacturing method of Example 2 implements said 2nd aspect P2, and this Example 2 differs from Example 1 only in operation conditions, and finish rolling acceleration rate 15 mpm / sec. It is said. And the manufacturing method of a reference example implements the said 3rd aspect P3, and this reference example is C: 0.005 mass% or less, Mn: 2.0 mass%, and other elements Is a high-Mn, low-carbon steel grade with a thickness of 3.2 mm that does not affect the phase transformation behavior, and a hot rolled steel sheet with a plate thickness of 3.2 mm. sec. And the operation / processing conditions are a finishing delivery temperature of 890 ° C. and a winding temperature of 640 ° C. The coil inner diameter was 750 mm, and the phase transformation rate was measured by the transformation rate meter 11. As a result, in Example 1, the entire length of the hot-rolled steel plate 4 was within 60% ± 10%. It was within 100% -10% over the entire range, and within the reference example , it was within 0% + 10% over the entire length of the hot-rolled steel sheet 4.

上述した結果から明らかなように本発明の上記二種類の態様および参考態様の熱間圧延鋼板の製造方法によれば何れも、巻取後に半径方向の面圧減少によるコイルの緩みが抑制されることから、コイラー内でのコイルつぶれの発生を抑制して生産性を向上させることができる。 As is apparent from the above-described results, the two methods of the present invention and the method for producing a hot-rolled steel sheet according to the reference embodiment of the present invention both suppress the loosening of the coil due to the reduction of the radial surface pressure after winding. Therefore, productivity can be improved by suppressing the occurrence of coil collapse in the coiler.

Claims

熱間圧延鋼板を熱間圧延機で熱間圧延した後に、これをホットランテーブル上で冷却し、コイラーで巻き取ってコイル状熱間圧延鋼板を製造するに際し、
前記熱間圧延鋼板を、熱間圧延機から送り出した直後のその熱間圧延鋼板の温度がその熱間圧延鋼板の長手方向に沿って一定となるように熱間圧延中に冷却した後、熱間圧延機からホットランテーブル上に一定速度で送り出し、
その熱間圧延鋼板を、熱間圧延機からの送り出しからコイラーでの巻取までの間の冷却速度と冷却時間とがその熱間圧延鋼板の長手方向に沿って一定となるようにホットランテーブル上で冷却することを特徴とする熱間圧延鋼板の製造方法。 After hot rolling the hot rolled steel sheet with a hot rolling machine, cooling it on a hot run table and winding it with a coiler to produce a coiled hot rolled steel sheet,
The hot-rolled steel sheet is cooled during hot rolling so that the temperature of the hot-rolled steel sheet immediately after being sent out from the hot rolling mill is constant along the longitudinal direction of the hot-rolled steel sheet. From a hot rolling mill, it is sent out on a hot run table at a constant speed.
The hot-rolled steel sheet is placed on the hot run table so that the cooling rate and cooling time from the delivery from the hot rolling mill to the winding by the coiler are constant along the longitudinal direction of the hot-rolled steel sheet. The manufacturing method of the hot-rolled steel plate characterized by cooling with.

前記熱間圧延鋼板を、熱間圧延機から送り出した直後のその熱間圧延鋼板の温度がその熱間圧延鋼板の長手方向に沿って一定となるようにする前記熱間圧延中の冷却は、仕上圧延機を構成する複数基の圧延スタンド間の冷却で行うことを特徴とする請求項１記載の熱間圧延鋼板の製造方法。 The cooling during the hot rolling so that the temperature of the hot rolled steel sheet immediately after the hot rolled steel sheet is sent out from the hot rolling mill is constant along the longitudinal direction of the hot rolled steel sheet, The method for producing a hot-rolled steel sheet according to claim 1, wherein cooling is performed between a plurality of rolling stands constituting the finish rolling mill.

熱間圧延鋼板を熱間圧延機で熱間圧延した後に、これをホットランテーブル上で冷却し、コイラーで巻き取ってコイル状熱間圧延鋼板を製造するに際し、
前記熱間圧延鋼板を、熱間圧延機からホットランテーブル上に加速しながら送り出し、
その熱間圧延鋼板を、単位長さ当りの冷却温度量が前記送り出し速度の上昇に比例してその熱間圧延鋼板の長手方向に沿って増加してその熱間圧延鋼板の全長に亘り冷却速度が一定となりかつ巻取時にその熱間圧延鋼板の全長に亘り相変態が終了するかまたは終了直前になるようにホットランテーブル上で冷却することを特徴とする熱間圧延鋼板の製造方法。 After hot rolling the hot rolled steel sheet with a hot rolling machine, cooling it on a hot run table and winding it with a coiler to produce a coiled hot rolled steel sheet,
Sending out the hot rolled steel sheet while accelerating from a hot rolling mill onto a hot run table,
The hot-rolled steel sheet has a cooling temperature amount per unit length that increases along the longitudinal direction of the hot-rolled steel sheet in proportion to the increase in the feed rate, and the cooling rate over the entire length of the hot-rolled steel sheet. A method for producing a hot-rolled steel sheet, characterized in that the cooling is performed on the hot run table so that the phase transformation is completed over the entire length of the hot-rolled steel sheet during winding or just before the end.

前記巻取時の熱間圧延鋼板の相変態率はその全長に亘り９０％以上であることを特徴とする請求項３記載の熱間圧延鋼板の製造方法。 The method for producing a hot-rolled steel sheet according to claim 3, wherein a phase transformation rate of the hot-rolled steel sheet at the time of winding is 90% or more over its entire length.

前記熱間圧延鋼板は、Ｃ：０．２５質量％以下（０質量％を含まず）、Ｍｎ：１．５質量％〜２．７質量％およびＳｉ：１．５質量％以下（０質量％を含まず）を添加したものであることを特徴とする請求項１から請求項４までの何れか１項記載の熱間圧延鋼板の製造方法。 The hot-rolled steel sheet has C: 0.25% by mass or less (excluding 0% by mass), Mn: 1.5% by mass to 2.7% by mass, and Si: 1.5% by mass or less (0% by mass). The method for producing a hot-rolled steel sheet according to any one of claims 1 to 4, wherein a hot-rolled steel sheet according to any one of claims 1 to 4 is added.