JPH05123713A - Manufacture of stainless steel strip - Google Patents

Abstract

(57) [Summary] [Purpose] To suppress linear flaws that occur near the side edges of stainless steel strips. [Structure] A method for producing a stainless steel strip having a chromium (Cr) content of 11 wt% or more by hot rolling is 10
On the side end surface of the slab (2) heated to 00 to 1300 ° C, the width (W) of the convex portion is 15 to 40 mm, and the height (H) thereof.
Is 40 to 50 mm, and the angle (θ) is 120 to 170 °
Sizing press using the mold (4) of
The slab after the pressing is subjected to rough pressure with a width reduction amount of 10 mm or less from the first stand to the intermediate stand.

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 a chromium (Cr) content of 11 wt% or more by hot rolling.

[0002]

2. Description of the Related Art In a conventional hot rolling method for a stainless steel strip, the mechanism of generation of linear flaws (hereinafter, referred to as seam flaws) at the end of the stainless steel strip during hot rolling is in the initial stage of rough rolling. It is considered that wrinkles are generated on the side edge surfaces of the slab, and these wrap around the surface as the rolling progresses, resulting in seam flaws on the surface.

The conventional countermeasures are to reduce the thickness of the slab,
There is a chamfering method for a slab corner (Japanese Patent Laid-Open No. 60-33803). However, this method is not practical because it has problems such as increased man-hours and poor yield.

As a method for making the slab side edge face concave (Japanese Patent Laid-Open Nos. 58-138502, 53-28542 and 61).
-52902 and 64-71503). However, since these all use vertical rolls 1 (a pair of vertical rolls, etc.) at the time of rough rolling, as shown in FIG. (These are called dog bones), and surface flaws other than seam flaws tend to occur. In addition, when the dog bone amount increases, the width expansion amount also increases,
As a result, the seam flaw width is increased.

Therefore, it is indispensable to find optimum conditions for the method of recessing the slab-side end face and the seam flaws, to minimize the amount of dog bones, and to prevent seam flaws near the slab-side end face. ing. Further, it is a precondition that it can be easily applied to an actual steel strip production line and does not cause a problem such as seizure.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a high-quality, high-yield stainless steel strip having a small number of surface flaws by suppressing the linear flaws generated in the vicinity of the side end portions of the stainless steel strip.

[0007]

The method for producing a stainless steel strip according to the present invention is a method for producing a stainless steel strip having a chromium (Cr) content of 11 wt% or more by hot rolling. The width (W) of the convex portion is 15 to 40 mm, the height (H) is 40 to 50 mm, and the angle (θ) is 120 to 1 on the side end surface of the slab heated to
Applying a sizing press using a 70 ° mold,
The above problem is solved by means of applying a rough pressure to the slab after pressing from the first stand to the intermediate stand with a width reduction amount of 10 mm or less.

[0008]

The reason why the Cr content is limited to 11% by weight or more of stainless steel is that in the production of hot-rolled steel strip, ordinary steel has a large amount of scale generation and almost no seam defects. The sizing press was used to move the dog bone position from the slab side end to the slab width center.

Due to the shape limitation of the mold, the width (W) of the convex portion of the mold is 15 m.
If it is less than m, as shown in FIG.
It is easy to get double bulging. Double bulging DB
The term "(B)" in FIG. 4 means a phenomenon in which a two-stage crack is generated at the plate end. In addition, when it is 41 mm or more, problems such as an increase in the amount of dog bones occur, and defects other than seam defects, such as rolling rolls, the ends of the dog bones collide, and the rolls are easily scratched or rough. Become.

The upper limit of the height (H) of the convex portion is set to 50 mm in consideration of the wraparound of the edge surface of the slab side, and the lower limit of the height (H) of the convex portion is set to 40 mm. The reason for this is that it was found that when the length is less than 40 mm, the slab concave portion becomes small, so that the influence on the seam flaw becomes small when the wraparound is taken into consideration.

The shape of the convex portion of the die is effective for minimizing the dog bone amount and moving the dog bone position from the slab side end portion to the slab width center portion. Rough rolling is performed with a width reduction of 10 mm or less from the first stand to the intermediate stand because if the width exceeds 10 mm, the slab recess becomes small or disappears, so there is no point in using the slab recess.

[0012]

EXAMPLES Examples of the method for producing a stainless steel strip according to the present invention will be described with reference to FIGS. 1 to 6.

First, the method of the present invention is applied to a method for producing a stainless steel strip having a chromium (Cr) content of 11 wt% or more by hot rolling.

As shown in FIGS. 1 and 2, the method of the present invention is
On the side end surface of the slab 2 heated to 000 to 1300 ° C,
The width (W) of the convex portion is 15 to 40 mm, and the height (H) is 4
A sizing press is performed using a mold having a thickness of 0 to 50 mm and an angle (θ) of 120 to 170 °. Next, the slab after pressing is subjected to rough pressure from the first stand to the intermediate stand with a width reduction amount of 10 mm or less.

In this way, it is possible to suppress linear flaws that occur near the side edges of the stainless steel strip. That is, as shown in FIGS. 2 and 3A, the sizing press of the die 4 reduces the dog bone amount G near the slab side end. It is speculated that this is because the action of force differs between the press and the rotating roll.

As shown in FIG. 6, in order to ensure that the central portion of the slab is pressed, the mold 4a is molded into a caliber shape, whereby the sizing press can be further stabilized.

As shown in FIG. 5, it can be seen that the method of the present invention drastically reduces the seam flaw width.

[0018]

According to the present invention, it is possible to obtain a method for producing a high-quality, high-yield stainless steel strip with a small number of surface flaws by suppressing the linear flaws generated in the vicinity of the side edges of the stainless steel strip. it can.

[Brief description of drawings]

FIG. 1 is a side view of a sizing press mold used in the method of the present invention.

FIG. 2 is a side view of a slab tip portion subjected to a sizing press according to the method of the present invention.

FIG. 3 is a plan view showing a dog bone generating mechanism,
(A) shows the method of the present invention, and (B) shows the conventional method.

FIG. 4 is a graph (A) showing the relationship between the width of the convex portion of the mold and the amount of double bulging, and an explanatory view (B) of double bulging.

FIG. 5 is a graph showing a relationship between a sizing press amount, a seam flaw width, and a dog bone amount.

FIG. 6 is a side view of another mold used in the method of the present invention.

[Explanation of symbols]

1: Vertical roll, 2: Slab, 3: Dogbone, 4:
Mold

Claims (1)

[Claims] 1. A method for producing a stainless steel strip having a chromium (Cr) content of 11 wt% or more by hot rolling, the width (W) of a convex portion on a side end surface of a slab heated to 1000 to 1300 ° C. ) Is 15 to 40 mm, its height (H) is 40 to 50 mm, and its angle (θ) is 120 to 1
Applying a sizing press using a 70 ° mold,
The slab after pressing is subjected to rough pressure with a width reduction amount of 10 mm or less from the first stand to the intermediate stand to suppress linear flaws generated in the vicinity of the side end portions of the stainless steel strip. And method for manufacturing stainless steel strip.