JPH0751728A - Descaling method of hot rolled stainless steel strip - Google Patents

Abstract

PURPOSE:To make a surface state smooth by grinding practically to the primary surface layer of a steel strip with a grinding brush roll, after annealing and treating with a mechanical scale breaker, and then immersing in an acid cleaning tank for an acid cleaning. CONSTITUTION:The arrangement of the equipment is in order of a mechanical scale breaker(MSB), heavy grinding brush roll and acid cleaning tank. In descaling, a shot blasting is not used and the acid cleaning is performed after the heavy grinding brush roll is used; therefore, by raising the performance of the grinding brush roll, a descaling is carried out without reducing the passing speed; moreover, the rough surface of the steel generated in a hot rolling is mitigated by the grinding of the base material; and a steel sheet with smooth surface without ruggedness is obtained. Thus, a grinding process is eliminated, and also, if the heavy grinding brush roll is used, one pass grinding is possible instead of a customary three pass grinding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a descaling method for hot rolled stainless steel sheets.

[0002]

2. Description of the Related Art Descaling / pickling of hot-rolled stainless steel strip is carried out by mechanical scale breaker (referred to as MSB), shot blast, sulfuric acid tank, mixed acid tank (nitric acid + hydrofluoric acid). Equipment is generally used. In some cases, a nitric acid tank may be installed after the mixed acid tank.

In Japanese Patent Laid-Open No. 53-108830, the MSB
According to the method, a scale is divided by, a pre-pickling is performed, shot blasting is used, grinding is performed with a rotating brush, and then pickling is performed.

[0004]

However, when shot blasting is used for descaling, when shot blast particles collide with the steel sheet, a large number of minute recesses are formed on the steel sheet surface (R _max 20-50μ
m). These recesses may cause oil pits in cold rolling, or in some cases, may be a starting point for generating surface defects, which have been a factor of inhibiting gloss of the cold rolled steel sheet.

An object of the present invention is to provide a descaling method for a hot rolled stainless steel strip which solves the above problems.

[0006]

Means for Solving the Problems The present invention is a method for manufacturing a hot rolled stainless steel strip. When the surface is descaled after annealing, it is first treated with a mechanical scale breaker, and then a grinding brush roll is used. It is a descaling method for a stainless hot-rolled steel strip, which is characterized by grinding to the steel background layer, and subsequently immersing in a pickling tank for pickling.
It is desirable to use a heavy grinding brush roll as the grinding brush roll. As the pickling tank, a sulfuric acid tank and a mixed acid tank of nitric acid and hydrofluoric acid are usually used.

The present invention makes it possible to descale without using shot blasting by using a grinding brush roll after MSB but before pickling. The difference between the heavy-duty brush rolls and the rotating brush rolls that have been generally used so far is that the grinding ability is improved by about 3 times, so that not only the scale but also the base material is targeted for grinding. That is the point. As a result, when a heavy grinding brush roll is used, not only descaling but also brush grinding improves the surface roughness and gives good results on the surface quality of the cold rolled steel sheet.

The heavy grinding brush roll is described in Japanese Patent Laid-Open No.
As disclosed in JP-A-315582, a rod-shaped body containing abrasive grains and having a diameter of 3 mm or more is radially mounted on a roll shaft, and has a polishing performance almost equal to that of a grinding wheel or a polishing disk. Is to have. More specifically, in a brush roll mounted with a rod-shaped body containing abrasive grains having a diameter of 3 mm or more on a roll shaft, radially with respect to the shaft circumference via a spring material and gathered in the axial direction The rod-shaped body and the grinding element body made of a spring material that is coupled to the bar-shaped body are arranged in a spiral shape, and the angle between the surface in the roll axis length direction and the spirally arranged surface of the grinding element body is 3 degrees or more. It is a brush roll in which each grinding element body is provided with an enlarged portion that restricts the movement of the body in the adjacent direction.

[0009]

According to the present invention, the descaling is performed by using the grinding brush roll without using shot blasting, and then performing pickling. Therefore, by improving the performance of the grinding brush roll, the stripping speed is not reduced. Not only can descaling be performed, but also the roughening of the surface of the steel sheet caused by hot rolling due to the grinding of the base material is reduced, and a steel sheet with a smooth surface can be obtained. At this time, the grindability may vary depending on the steel type, but it is very effective to dispose two or three grinding brush roll facilities in tandem.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an equipment layout diagram for carrying out the present invention.
The mechanical scale breaker (MSB), heavy grinding brush roll, and pickling tank are arranged in this order. FIG. 2 is a layout view of equipment for the conventional descaling method, in which the mechanical scale breaker, shot blast, and pickling tank are arranged in this order.

FIG. 3 shows the results of the descaling test when using shot blast, a rotating brush, and a heavy grinding brush roll. In FIG. 3, the horizontal axis indicates the strip passing speed,
6 is a graph showing the difference in weight of steel plates before and after descaling on the vertical axis. Also, ○ in the plot indicates good descaling, ×
Indicates that there is scale remaining. From FIG. 3, it was possible to perform descaling at a stripping speed of 40 mpm with MSB + shot blast + rotary brush, which has been the descaling method so far. Also, without shot blasting, the plate passing speed is 20mp
Descaling was possible below m. On the other hand, it can be seen that even when the heavy grinding brush is used without using the shot blast, the descaling ability is almost the same as that of the conventional MSB + shot blast + rotary brush.

FIG. 4 shows the three-dimensional roughness of the steel sheet surface after descaling. As can be seen from FIG. 4 (b),
It can be seen that in the shot blast + rotary brush, the recesses generated during shot blast remain. On the other hand, in the case of (a) using the heavy grinding brush, since the shot blasting is not used, the concave portion is not seen,
It can be seen that the plate surface is extremely smooth.

[0013]

According to the present invention, when the stainless hot rolled steel sheet is descaled, the grinding brush is used instead of shot blasting. Therefore, the surface quality of the steel sheet can be kept extremely high while maintaining the descaling ability at the same level. Can be smoothed. This makes it possible to omit the grinder step after pickling of the hot-rolled steel strip, which has been required until now in order to produce a BA material, which is the highest grade of gloss of a stainless steel plate. Also, when using a heavy-grinding brush roll, one that was performing 3-pass grinding was 1
It became possible by pass grinding. Further, even when it is applied to 2B material, which is the second gloss grade, there is an effect that the defective gloss so far is drastically reduced and the pass rate is improved.

[Brief description of drawings]

FIG. 1 is an equipment layout diagram 1 used for implementing the present invention.
Explanatory drawing which shows an example.

FIG. 2 is an explanatory diagram showing a conventional equipment layout diagram.

FIG. 3 is a graph showing the test results of descaling.

FIG. 4A is a schematic diagram showing the present invention, and FIG. 4B is a schematic diagram showing the three-dimensional roughness of the surface of the steel sheet descaled in the conventional example.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Yamamoto 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Works (72) Inventor Nio Yokozawa 1 Kawasaki-cho, Chuo-ku, Chiba-shi Kawasaki Steel Co., Ltd. Chiba Works (72) Inventor Setsuo Hotani 1452 Foki, Nogami Town, Seagrass County, Wakayama Prefecture Hotani Co., Ltd.

Claims (3)

[Claims] 1. In the method for producing a hot rolled stainless steel strip, when descaling the surface after annealing, first treating with a mechanical scale breaker and then grinding with a grinding brush roll to substantially the steel background layer. A method for descaling a hot-rolled stainless steel strip, which is characterized by subsequent immersion in a pickling tank and pickling. 2. The descaling method for a hot rolled stainless steel strip according to claim 1, wherein a heavy grinding brush roll is used as the grinding brush roll. 3. The descaling method for a hot-rolled stainless steel strip according to claim 1 or 2, wherein the pickling tank comprises a sulfuric acid tank and a mixed acid tank of nitric acid and hydrofluoric acid.