JPS61126909A - Working and heat treating installation in rolling line for thick plate - Google Patents

Abstract

PURPOSE:To obtain the stable flatness of a material by arranging successively a reheater, straightener and cooler on the outlet side of a hot rolling mill. CONSTITUTION:The billet heated in a heating furnace 1 is transferred by a conveying table 2, is passed through a descaler 3 and is rolled to a prescribed size by a rolling mill 4. The rolled plate is heated according to a heat treatment for working in a reheating furnace and at the same time the ununiform temp. in the plate generated during rolling is made uniform. The plate is then flattened by the straightener 6 and is subjected to the cooling meeting purposes by the cooler 7.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention is directed to a thick plate rolling line for performing rJaI heat treatment such as direct quenching or η0 speed cooling on-line without impairing the flatness of thick steel plates. Regarding processing heat treatment equipment.

(b) Prior art Recently, direct quenching, or Ar Processing heat treatment such as accelerated cooling, which performs antibacterial cooling from the temperature on the point plate to 650° C. or lower, is carried out online.

Various types of equipment have been proposed in the past for performing such processing and heat treatment. For example, ■Following the hot rolling mill,
Accelerated cooling equipment, re-FM heat furnace, and straightening machine arranged in this order, or F! One in which the heating furnace and straightening machine are arranged in reverse (Japanese Patent Publication No. 59-34213), ■ one in which the hot rolling mill is followed by the heating furnace and then the quenching device (Japanese Patent Publication No. 56/1986).
-1615), ■Following the hot rolling mill, maintain the heat insulation cover! One in which the equipment, hot leveler, and water cooling device are arranged in this order (Japanese Patent Application Laid-open No. 116732/1983), and one in which the hot rolling mill is followed by an induction heating device and a quenching mill (
JP-A No. 58-87216), etc.

However, in the processing heat treatment apparatus (2), thermal energy loss occurs when obtaining a thick steel plate with good fA flatness. η After 0-speed cooling, the edge flatness (edge wave) caused by the temperature drop at the edge of the steel plate is corrected using a hot leveler, and the temperature difference is corrected by reheating to 500 to 500 Ac. In order to eliminate this and ensure flatness, the steel plate must be reheated after accelerated cooling, and the heat retained after hot rolling is not effectively utilized, resulting in thermal energy loss.

With the wafer processing apparatuses (1) and (2), it is difficult to obtain a thick steel plate with good flatness, and it is not practical. With these devices, temperature variations during hot rolling and ensuring the maximum quenching degree can be resolved by reheating using a reheating furnace, induction heating device, etc., but flatness defects that occur during hot rolling cannot be reheated. If the flatness is poor before cooling, it will not be possible to cool uniformly (this is one of the causes of temperature variations in the thick steel plate after cooling), and the flatness will worsen (cooling). (deteriorating flatness due to non-uniformity). For this reason, in order to straighten the flatness of a thick steel plate after quenching, a general hot repeller has a hard to straighten hole, so a powerful cold repeller is required, which is disadvantageous in terms of equipment energy. With,
The correction itself is also difficult.

In addition, in the processing heat treatment vI apparatus of (2), a hot leveler is placed in front of the reheating furnace, and after straightening the flatness, reheating and direct hardening are performed. In this way, by hardening after straightening the flatness, the flatness does not deteriorate, which is advantageous for ensuring flatness. However, not all thick steel plates after hot rolling are straightened by a hot leveler. For example, it is difficult to correct the flatness of steel plates with a low finish, or with a large yield load at that temperature depending on the material and plate thickness. Requires bending load,
The hot leveler will not eliminate the problem and it will remain, resulting in poor flatness of the thick steel plate after direct quenching.

The heat retention device of the processing heat treatment equipment (①) does not completely prevent @low F, and although it can prevent the temperature non-uniformity in the width direction of the sheet that occurs during rolling from becoming larger,
＠It is not possible to make uniformity of temperature variations. Therefore, if there is any variation in the degree of flatness of a thick steel plate before cooling, even if the flatness is corrected with the next hot repeller, the temperature variation will remain and the flatness will deteriorate during cooling. It is not.

As described above, if there are degree variations or flatness defects before cooling, not only will a thick steel plate with good flatness not be obtained after cooling, but residual stress and residual strain will occur in the subsequent thick steel plate. This residual stress and residual strain are partially released when the product is cut, resulting in so-called camber, which causes the product to bend sideways.

As mentioned above, the conventional ITO heat treatment equipment has one advantage in obtaining θ loe heat treated thick steel plates with stable flatness.
It had

(/-1 Problems to be Solved by the Invention The problem to be solved by the present invention is to process the material in a plate rolling line so as to give it a uniform coagulation distribution, thereby creating a stable material. It is superior to the Chloe heat treatment equipment that can obtain a flatness of .

B) Means for solving the problem The processing heat treatment equipment of the present invention is installed in a thick plate rolling line,
The above problem is solved by sequentially arranging a reheating device, a straightening machine, and a cooling device on the exit side of the hot rolling mill.

In this processing heat treatment equipment, the rejJO heat equipment,
It is also possible to provide the straightening machine and the cooling equipment on a separate line, and to connect this line with the plate rolling line by a 7-way transformer.

(E) Embodiment The rolling heat treatment equipment in the thick plate aE rolling line of the present invention is characterized in that a hot rolling mill is followed by a reheating mill, a straightening machine, and a cooling mill. It is. FIG. 1 shows an embodiment of the present invention. In the figure, 1 is a heating furnace for the billet before rolling, which may be a commonly used continuous heating furnace or a punch type 8-neck heating furnace, and 2 is a conveyance table that transfers the billet or steel plate in the direction of the arrow. , usually a roller type is used. 6 is a descaling process that removes oxidized scale from the steel after reheating, usually using high-pressure water. The scale is removed by spraying onto the surface of the steel piece or by mechanically rolling it down and then spraying high-pressure water. 4 has an EE rolling mill,
Normally, a reversible rolling mill with double or quadruple rolls is used to roll thick steel plates, but a continuous type or two
It may also be a series of rolling mills.

In the following, 1 to 4 should be arbitrarily selected depending on the size, type, and quantity of the steel piece or steel plate to be imitated, and the present invention does not require any particular limitation.

5 is a reheating device that chromatically heats the steel plate after hot rolling, and the type of installation is a gas or liquid fuel combustion heating furnace, or an electric zero heating iron such as high frequency or low frequency induction heating. position is used. The main purpose of the reheating stage 5 is to raise the temperature to the optimum cooling start temperature for each type of product for direct hardening or rapid cooling, and to eliminate differences in board temperature, but this will be described later. It can also be used for purposes such as 6 is a straightening machine, generally a hot repeller is used to correct flatness defects caused during hot rolling, achieve uniform cooling during cooling, and prevent flatness from deteriorating due to cooling. 7 is a cooling equipment, which performs direct hardening, accelerated cooling, and cooling depending on the purpose. Cooling equipment 7
The models include a model that sprays out a large amount of water,
A laminar flow type in which water is ejected in a columnar or curtain shape, a combination thereof, a roller quenching/chipping type, etc. are used.

In the equipment shown in Fig. 1, a steel billet heated in a heating furnace 1 is transferred by a conveyance table 2 and rolled into a predetermined size by a rolling mill 6 (processing J: temperature is approximately 1000 to 700°C). . Next, in the reheating furnace 5, depending on the processing heat treatment, for example, in the case of direct quenching, it is heated above the A r g point (about 900°C or more), and in the case of accelerated cooling, it is heated to above 700°C VcrJa, and the internal temperature of the plate generated during rolling is The non-uniformity is made uniform and flattened by a straightening machine 6, and cooling is performed in a cooling device 7 according to the purpose.

Figure @2 has substantially the same configuration as Figure 141, but the reheating machine 5, the straightening machine 6, and the cooling machine 7t are arranged in separate lines. ■1 The steel plate subjected to heat treatment must be
The steel plate is sent to another line by the post-transfer equipment, and the steel plate that is not subjected to processing heat treatment is directly sent to the transfer table 2 by I/cW. Therefore, the rolling capacity of the entire rolling mill 4 is improved.

According to the processing heat treatment equipment of the present invention, the steel plate f after hot rolling
I: First, the temperature is raised to the optimum cooling start temperature in the FFO heat furnace, the inside surface of the plate is made uniform, and the flatness is further made to be 7 lats using a straightening machine. Therefore, the conventional problems such as deterioration of flatness during cooling due to non-uniformity of VC or poor flatness, problems of residual stress and residual strain after non-uniform cooling, and ensuring the optimum cooling start temperature are solved. Therefore, after heat treatment, a thick steel plate with excellent flatness can be obtained. In addition, it is easy to roll and straighten steel sheets that have been heated once, even if the temperature is lowered or the thickness of the steel sheet is increased.
In addition to being able to carry out I heat treatment, excellent flatness can also be obtained in RI heat treatment.

In the following explanation, the present invention is applied to the heat treatment.

I mentioned the case where it is used, but il! The following rolling is also possible by utilizing the heated rolling mill. For example, for Wa7JIX materials, such as titanium alloys and stainless steel alloys, whose deformation resistance increases rapidly as the temperature decreases, conventionally, the raw material steel billet after heating is rolled to an intermediate thickness, and then heated again and rolled. Rolling or 6-heat rolling is performed to produce a product with a predetermined thickness. However, for such a material, if the rolling temperature is lowered and the rolling is interrupted, it is possible to perform rolling in which the temperature is raised in the reheating mill 5 and the rolling is continued again. By performing this type of rolling, the manufacturing schedule is shortened compared to conventional methods, and less energy is required for one round just for heating up.Furthermore, the finishing temperature can be increased, and subsequent flatness correction is required. There are advantages such as ease of

(f) Specific example @ 1 Thickness 15mm x length 20000m with chemical components shown in table
A thick steel plate after hot rolling was reheated using the processing heat treatment equipment of the present invention under the conditions shown in Table 2, and then quenched and quenched directly. Figure 6 shows the degree variation at the start of cooling compared to the quenched product.

FB), the flattened metal after cooling is shown in Figure 4, and the mechanical test is shown in Table 6.

Table 2 Table 5 Thickness 1 using recombination heat treatment equipment 5 of processing heat treatment equipment of the present invention
80 mm x width 1000 mm x length 1800 mm 5US316
From the slab thickness 6M x width 3000w x length 18000
mIC rolling was performed.

After heating the slab to 1,150°C, it was rolled to an intermediate thickness of 20 mills, and the temperature was raised from 750°C to 1,050°C in a reheating step [5], followed by rolling 2 to a thickness of 6. The finishing temperature and thickness at this time was 800°C, and rolling could be carried out without any particular delay. The leveling flatness was also good.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of one row of Chloe% pigeon treatment equipment based on the present invention. FIG. 2 is a drawing similar to FIG. 1 and shows an alternative implementation 1y11. FIG. 6 is a graph showing a comparison between a product obtained by the equipment of the present invention and a conceptual product obtained by the conventional technique in terms of distribution in the width direction. FIG. 4 is a graph showing a comparison of both products similar to FIG. 6 in terms of flatness in the width direction. 1: Billet V-mouth heating furnace 2: Conveying table 6: Descaling pupil 4: Rolling machine 5: Re-JTI heating device 6: Straightening machine 7: Cooling IN
t8: Transfer Minatoki patent applicant Sumitomo Metal Industries, Ltd. (5 others)? 3 :) 67 Figure 3 Figure 4 Slope 11 @ (4vL%)

Claims (2)

[Claims] (1) In the plate rolling line, on the exit side of the hot rolling mill,
Processing and heat treatment equipment characterized by sequential arrangement of reheating equipment, straightening equipment, and cooling equipment. (2) Claim (1) characterized in that the reheating device, straightening machine, and cooling device are provided in separate lines, and the line and the plate rolling line are connected by a transfer device. equipment.