JP2734289B2 - Method for producing stainless steel strip with excellent surface properties and plate shape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a stainless steel strip having excellent surface properties and sheet shape, and rolling a stainless steel with a cold tandem rolling mill to obtain a stainless steel strip having excellent surface properties and sheet shape. It is intended to provide a method of manufacturing a band.

[0002]

2. Description of the Related Art In recent years, a stainless steel strip is rolled by a tandem rolling mill for rolling ordinary steel, using a work roll having a diameter larger than that of a Sendzimir mill.
For example, JP-A-59-38334, JP-A-59-10
No. 7030 discloses a method of cold rolling with a work roll having a large diameter of 150 mm or more.

[0003] When a stainless steel strip is rolled by this tandem mill, a large-diameter work roll is used and an emulsion oil having a large cooling capacity is used as compared with a Sendzimir mill. Rolling oil is drawn in, and high-speed rolling can be performed without generating heat scratches caused by oil film breakage.

[0004]

However, in the prior art as described above, when the rolling oil is drawn in,
The work roll and the steel sheet are less likely to come into contact with each other, and as a result, the surface properties of the steel strip surface after rolling are significantly worse than in the case of the Sendzimir mill, and the stainless steel strip rolled by the tandem rolling mill is compared with the Sendzimir mill rolled material. Thus, there is a problem that the gloss of the product is remarkably inferior.

A method for solving this problem is disclosed in
JP-A-119908 discloses a method of rolling at least the final stand with a work roll diameter of 400 mm or less and a total rolling reduction of 70% or more. When the rolling reduction is large, heat scratches are likely to occur due to oil film breakage, and the high load is applied to the small-diameter roll, which increases the roll deflection and significantly deteriorates the shape of the rolled steel sheet. Occurs.

The present invention has been studied to solve the problems of the prior art as described above, and adopts a specific reduction ratio in relation to the roll diameter to thereby obtain a steel strip which is excellent not only in surface characteristics but also in plate shape. Which is as follows.

When rolling stainless steel using a cold tandem rolling mill, the final and immediately preceding roll diameters are set to 1
Rolling is performed with a work roll of 100 to 250 mm, and the rolling reduction of the final stand does not exceed the rolling reduction of the immediately preceding stand, and remains at 2 to 15%, and the cumulative rolling reduction of the final two stands is 15 to 40%. Characterized by the fact that
A method for producing a stainless steel strip having excellent surface properties and plate shape.

[0008]

When rolling a stainless steel strip with a cold tandem rolling mill, the smaller the work roll diameter, the higher the glossiness of the steel strip surface after rolling. This is because the amount of the rolling oil drawn in between the work roll and the steel strip decreases, and the work roll surface is easily transferred to the steel strip surface. However, in order to reduce the diameter of all the stands of the cold tandem rolling mill, large equipment costs are required. Then, after rolling by 30% to 50% with a large-diameter roll mill of 600 mm, rolling was performed with various roll diameters, and the glossiness was measured. The result is shown in FIG.
As shown in FIG.

That is, according to the results of FIG. 1 obtained as described above, after rolling by a large-diameter roll,
It is clear that the glossiness is remarkably improved when a cumulative rolling reduction of 15% or more is given with the following roll diameter. However, it is also understood that the greater the cumulative reduction ratio, the higher the glossiness but the higher the probability of occurrence of heat scratch. Although the glossiness is remarkably improved in a roll having a diameter of less than 100 mm, the difference in diameter from the large-diameter roll in the preceding stage becomes large, and the difference in flatness of the roll deteriorates the plate shape and is not preferable in securing the rolling speed.

[0010] It is also known that the higher the rolling reduction in each pass, the greater the improvement in glossiness, but the probability of occurrence of heat scratch increases, and the plate shape is significantly deteriorated. In this case, as shown in FIG. 2, by further applying a slight reduction of 10% or less, the shape can be corrected while improving the glossiness, and the surface properties after rolling with the Sendzimir milled material become equivalent.

That is, the rolling reduction of the final stand does not exceed the rolling reduction of the immediately preceding stand, and the cumulative rolling reduction at the final stand and the immediately preceding stand is 2 to 15%, so that the surface characteristics and the plate shape are excellent. Stainless steel strip.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a cold tandem rolling mill consisting of stands # 1 to # 5, work rolls having diameters A to J as shown in Table 1 below are used. Each of the stands is a large-diameter roll of 600 mm, and the # 4 stand is 600 mm for A to C, 200 mm for D to H,
I is 250 mm and J is 150 mm. Stand # 5 is 600mm for A, 400mm for B, and 200m for each of CH.
m and I are 250 mm and J is 150 mm.

[0013]

[Table 1]

In Table 1, the rolling reduction is as shown in parentheses in each column. When only a large-diameter roll is used as in Case A, the rolling reduction of the # 4 and # 5 stands is the total. Even if the final stand is 10%, the glossiness after rolling is very low.

On the other hand, in case B, when the # 5 stand, which is the final stand, is 400 mm, the glossiness after rolling is still insufficient even if slightly increased.

Case C is a case where the final stand is a roll of 200 mm, and the gloss is further increased by this. However, the rolling reduction of the final stand is 17%, which exceeds the upper limit of the present invention. , Heat scratch occurs,
The plate shape is not preferable.

Case D is a case where the final stand and the immediately preceding stand are both rolled with a roll of 200 mm. However, when the cumulative reduction rate at the final stand and the immediately preceding stand is 12%, which does not reach the lower limit of the present invention. As a result, the rolling gloss becomes insufficient.

Further, also in case E, both the final stand and the immediately preceding stand are rolls of 200 mm, and the glossiness after rolling is greatly improved to 450%.
It has become. However, in this case, the shape of the plate cannot be made favorable, and heat scratches also occur.

On the other hand, in case F, the rolls up to the # 3 stand are the same as in the cases A to C, and the rolls # 4 and # 5
The roll of the stand is the same as in case D, except that the rolling reduction in the final stand # 5 is 10%,
This is a case where the rolling reduction of the # 4 and 5 stands is 25%, and by doing so, a product having glossiness equal to or higher than that of the Sendzimir mill of case K and a good plate shape is obtained. .

Cases G and H have the same roll diameter as case F. Case G is a case where the rolling reduction of the final stand and the immediately preceding stand is reduced, and case H is a case where the rolling reduction of the final stand is reduced. However, in these cases, favorable glossiness was obtained in each case.

In cases I and J, the roll diameters of the stands # 1 to # 3 are the same, and the stands # 4 and # 5 are
In the case where the roll diameter is larger and the case where the roll diameter is smaller than in the case of H, favorable favorable glossiness is obtained in each case,
In particular, the case J has the highest glossiness.

[0022]

According to the present invention as described above, a stainless steel strip excellent in both surface characteristics and plate shape can be appropriately obtained by a cold tandem rolling mill. This is an invention with a great effect.

[Brief description of the drawings]

FIG. 1 shows 30% to 50% rolling by a large-diameter rolling mill.
It is the table | surface which showed the relationship between the total rolling reduction and the surface glossiness about what was rolled by the roll of 00-400 mm (phi).

FIG. 2 is a table also showing a relationship between a one-pass rolling reduction with a small-diameter roll in a final stand, a surface glossiness, and a plate shape (steepness).

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadaka Masuda 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (56) References JP-A-59-38334 (JP, A) JP-A-63 -119908 (JP, A) JP 2-14122 (JP, B2)

Claims (1)

(57) [Claims] When rolling stainless steel using a cold tandem rolling mill, the final and immediately preceding rolls are rolled with a work roll having a diameter of 100 to 250 mm, and the rolling reduction of the final stand is the rolling reduction of the immediately preceding stand. The method for producing a stainless steel strip having excellent surface properties and plate shape, characterized in that the total rolling reduction of the last two stands is 15 to 40% without exceeding 2%.