JPH0236324B2 - 2SOKURATSUDOKINZOKUBANNONETSUKANKYOSEIHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for hot straightening a two-layer clad metal plate.

[Prior Art] Even if a two-layer clad steel plate made of a laminated material such as stainless steel or Cypronickel and a base material such as carbon steel is flat at the end of rolling, the plate will deform as the temperature of the steel plate decreases thereafter. Distortion or warpage occurs in the width and length directions. That is, as shown in FIG. 2, the clad steel plate 1 is made up of two plate materials 1A and 1B having different coefficients of linear expansion. Therefore, when the steel plate 1 undergoes a cooling process, it curves so that the plate material 1A, which has a large coefficient of linear expansion and a large amount of shrinkage, is on the inside, causing distortion or warping.

In response to this, the present applicant proposed a method for straightening the warpage of a double-layer clad steel sheet as disclosed in Japanese Patent Application Laid-Open No. 59-42122,
We have achieved results.

That is, the method according to JP-A-59-42122 is as follows:
When straightening a rolled clad steel plate in a hot straightening machine, by forcibly cooling the steel plate side with a large amount of heat shrinkage before or during hot straightening, the temperature difference between the side of the steel plate with a large amount of heat shrinkage and the side of the steel plate with a small amount of heat shrinkage is created. , and the same amount of warpage as after cooling is achieved in advance, and this state is flattened using a hot leveler or the like, thereby making it possible to prevent warping after cooling to room temperature.

[Problems to be Solved by the Invention] However, in reality, clad steel sheets begin to warp as soon as they are cooled immediately after hot rolling. It is difficult to uniformly supply cooling water spouted from a header or the like in the width direction and length direction of the steel plate. Furthermore, clad steel plates often have internal distortion due to their processing history, such as hot rolling.

Therefore, when using the above conventional hot straightening method, it is difficult to provide a sufficient straightening effect to the clad steel plate, and it is difficult to straighten the shape of the clad steel plate to a flat shape after cooling to room temperature. .

The object of the present invention is to provide sufficient warpage correction to a clad metal plate.

[Means for Solving the Problems] The present invention provides a hot straightening method for a two-layer clad metal plate consisting of a base material and a laminate, in which after hot straightening the metal plate after hot rolling, By forcibly cooling the metal side of the metal plate that has a large amount of thermal contraction, the metal plate is hot-straightened again under conditions that create a temperature difference between the two metals.

[Function] According to the present invention, after flattening the clad metal plate and removing distortions from previous processing, a straightening operation that involves forced cooling is performed. This makes it possible to uniformly supply the cooling fluid in the width direction and length direction of the clad metal plate. In addition, under the condition that the influence of internal distortion from the previous processing is removed, the metal side with a large amount of thermal contraction is corrected and cooled using the above cooling fluid, and the same amount of warp as after cooling is realized in advance. will be corrected to be flat. Therefore, it becomes possible to perform sufficient warpage correction on the clad metal plate.

[Example] FIG. 1 is a layout diagram showing an example of a correction device used for implementing the present invention. In Figure 1, 11
1 is a hot rolling mill, 12 is a first straightening device, and 13 is a second straightening device.
It is a correction device. The second straightening device 13 includes cooling fluid supply means such as a cooling spray header between the straightening rollers. The hot rolling mill 11 and the first straightening device 12 or the second straightening device 13 are separated by a distance L, and the clad steel sheet 1 rolled by the hot rolling mill 11 is transported over the distance L. During this process, warping as shown in FIG. 2 occurs.

Therefore, in the present invention, the first straightening device 12 first applies hot straightening to the clad steel plate 1 without actively creating a temperature difference between the base material and the laminate material of the clad steel plate 1. . Next, the second straightening device 13 forcibly cools the metal side of the clad steel plate 1 with a large amount of thermal contraction using a cooling spray header or the like, thereby creating a temperature difference between the base material and the laminate material. Under the current conditions, it will be hot straightened.

In addition, in the above-mentioned first straightening device 12, the meaning of "not actively applying a temperature difference" between the base material of the clad steel plate 1 and the laminate material means that normal hot straightening is performed. Normal hot straightening is straightening without actively applying a temperature difference using a cooling device, etc., and there may be a temperature difference caused by air cooling difference between the upper and lower surfaces, table roller cooling, etc. .

FIG. 3 is a diagram showing the relationship between the elapsed time, the amount of warpage, and the average temperature of the clad steel sheet 1 subjected to various straightening methods. A is the case where the specimen is allowed to cool after hot rolling, and the warpage after cooling to room temperature is maximum. b is
This is a case of normal hot straightening without forced cooling. Case c shows the case where hot straightening accompanied by forced cooling according to the above-mentioned Japanese Patent Application Laid-Open No. 59-42122 is performed, and if forced cooling and restraint are not appropriate, warpage will remain after cooling to room temperature. d is the case according to the present invention, and it is observed that the warpage after cooling to room temperature is extremely small.

That is, according to the present invention, after flattening the clad steel plate 1 and removing the distortion caused by the pre-processing, a straightening operation that involves forced cooling is performed. This makes it possible to uniformly supply the cooling fluid in the width direction and length direction of the clad steel plate 1. In addition, under the condition that the influence of internal strain from pre-processing is removed,
The metal side, which has a large amount of thermal contraction, is forcibly cooled by the cooling fluid, so that the same amount of warp as after cooling is realized in advance, and this state is corrected to be flat. Thereby, it becomes possible to perform sufficient warpage correction on the clad steel plate 1.

In addition, in implementing the present invention, the second correction device 1
The hot straightening that should be applied at the stage before the hot straightening accompanied by forced cooling in step 3 can also be performed only by the second straightening device 13 without using the first straightening device 12. In that case, first, hot straightening is performed on the clad steel plate 1 without operating the cooling spray header of the second straightening device 13, and then the cooling spray header of the second straightening device 13 is heated. Clad steel plate 1 under the condition of operating the door etc.
The clad steel sheet 1 is subjected to hot straightening while being cooled.

Hereinafter, specific implementation results of the present invention will be explained.

After rolling a stainless clad steel plate with stainless steel as the laminated material and carbon steel as the base material, with a total thickness of 20 mm and a cladding ratio (laminated material thickness/total plate thickness) of 30%, 59-42122 and correction method B based on the present invention were applied.

Here, the clad steel sheet obtained by hot rolling is flat immediately after rolling, but during the cooling process until it reaches the hot straightening machine, the stainless steel side, which has a large amount of heat shrinkage, is turned inside. A warpage of about 120mm occurs.

In the straightening method A based on the above-mentioned Japanese Patent Application Laid-Open No. 59-42122, a clad steel plate, which is at an entrance temperature of 750°C on the entrance side of a straightening machine, is straightened in three passes with cooling of one side of the clad steel plate by a spray header. Straightening was completed with the exit temperature being 550°C for the stainless steel on the bottom side and 650°C for the carbon steel on the top side. The above-mentioned clad steel plate is flat during straightening, reversely warps (-) due to reheating after straightening, and remains (+)50mm warped at room temperature after cooling. Summer.

On the other hand, in straightening method B based on the present invention, first, the clad steel plate, which is at an entrance temperature of 770°C, is straightened in three passes on the entrance side of the first straightening device 12,
Flattened. Next, the clad steel plate, which is at an entrance temperature of 740°C on the entrance side of the second straightening device 13, is
By straightening the clad steel plate in three passes with cooling on one side using a spray header, the temperature of the stainless steel on the bottom side was 540℃, and the temperature of the carbon steel on the top side was 640℃.
Straightening was completed with the outlet temperature at . The above-mentioned clad steel plate is straightened by the first straightening device 12 to remove the warpage caused by cooling after rolling and to equalize the residual stress, so that the subsequent straightening with forced cooling by the second straightening device 13 is performed. It becomes possible to further increase the effect. Therefore, after completion of correction,
Although a large warpage appears due to recuperation, the reverse (-) warpage gradually decreases with subsequent cooling, and it becomes possible to finally achieve a state of warpage close to zero.

Incidentally, FIG. 4 shows the results obtained by the straightening device arrangement including both the first straightening device 12 and the second straightening device 13 shown in FIG. On the other hand, when the present invention is implemented with a single straightening device, although the occurrence of negative (-) warping due to recuperation is delayed, the same effect as shown in Fig. 4 can be obtained as a result. It is.

[Effects of the Invention] As described above, the present invention provides a hot straightening method for a two-layer clad metal plate consisting of a base material and a laminate material.
After hot straightening the hot-rolled metal plate, the metal side of the metal plate with a large amount of heat shrinkage is forcedly cooled to create a temperature difference between the two metals. The plate is hot-straightened again. Therefore, it becomes possible to perform sufficient warpage correction on the clad metal plate.

[Brief explanation of drawings]

Fig. 1 is a layout diagram showing an example of the straightening device used in the implementation of the present invention, Fig. 2 is an end view showing the warped state of the clad steel plate, and Fig. 3 is the elapsed time of the clad steel plate subjected to various straightening methods. FIG. 4 is a diagram showing the relationship between the amount of warpage, the amount of warpage, and the average temperature, and FIG. 4 is a diagram showing the concrete implementation results of the present invention. 1... Clad steel plate, 11... Hot rolling mill, 1
2...first correction device, 13...second correction device.

Claims (1)

[Claims] 1. In a hot straightening method for a two-layer clad metal plate consisting of a base material and a cladding material, after hot straightening the metal plate after hot rolling, the metal side of the metal plate having a large amount of heat shrinkage is forced. A method for hot straightening a two-layer clad metal plate, which comprises hot straightening the metal plate again under a condition where a temperature difference is created between the two metals by cooling.