JPH0751727A - Manufacture of hot rolled stainless steel strip - Google Patents

Abstract

PURPOSE:To thin scale layer after annealing and reduce scale remainder defects, etc., by performing a surface grinding of a stainless steel strip with a grinding brush roll before annealing and creating a state with scales practically removed or lightly remaining. CONSTITUTION:A stainless steel strip coil 1 after annealing is first put on a heavy grinding brush roll 2; and on one hand, after a scale layer is practically removed, an austenitic stainless steel is put through a continuous annealing furnace 4, mechanical scale breaker(MSB) 5, shot blasting device 6 and acid cleaning equipment 7. On the other hand, a ferritic stainless steel, after treated in a batch annealing furnace, put through the treatment after the mechanical scale breaker 5, After a hot rolling, the surface oxidized layer is removed or made into a state having a light scale with a grinding brush roll 2; and therefore, the scale after the annealing is thin and easily peelable.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Generally, stainless steel strips after hot rolling are
Oxide scale (hereinafter scale) generated when annealing was performed without any special treatment on any of ferritic, austenitic, and martensitic stainless steels.
Is removed by continuous annealing and pickling equipment.

However, when hot-rolled and then annealed without special annealing pretreatment, the scale is 30%.
Descaling must be done by making use of mechanical scale breaker (hereinafter referred to as MSB), shot blasting, pickling, etc. At this time, the scale may not be completely removed due to the rough surface of the steel sheet, and a reprocess treatment may be required.

Further, particularly in the case of austenitic stainless steel, in the continuous annealing pickling line, when passing through the continuous annealing furnace,
The scale may adhere to the roll in the furnace to form a pickup, which may cause a flaw on the plate surface. Therefore, recently, for ferritic and martensitic stainless steels for the purpose of scale modification, hydrogen annealing using hydrogen as an atmosphere during annealing (Japanese Patent Application Laid-Open No. 4-165050) has been carried out. Have been successful. That is, by using hydrogen as a reducing gas, the scale on the surface is reduced, and as a result, the scale thickness is thinned and descaling is facilitated. However, this method has a drawback that the investment amount for equipment is large.

For austenitic stainless steel, a method of modifying the scale by applying an alkaline earth metal chloride solution before annealing (Japanese Patent Laid-Open No. 51782/1993)
No. 7) is disclosed. This is to descale the steel strip by the reaction of chloride and scale. Vitreous substances are generated on the surface, and in cooling after annealing, the scale is easily peeled off by utilizing the difference in coefficient of thermal expansion between the vitreous substance and the base material. However, it has not reached the level of practical use yet.

[0006]

In view of the above-mentioned prior art, the present invention can reduce scale residue defects and hearth roll defect defects after passing through a continuous annealing pickling line by relatively inexpensive means. It is an object of the present invention to provide a method for manufacturing a stainless hot-rolled steel strip.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a hot rolled stainless steel strip in which hot rolled stainless steel strip is subjected to batch annealing or continuous annealing and then continuous pickling, in which a grinding brush roll is provided before the annealing. Is a method for manufacturing a stainless hot-rolled steel strip, which is characterized in that the surface of the hot-rolled steel strip is substantially ground to remove the scale or the light-scale state, and the grinding brush roll is a heavy grinding brush roll. Is desirable. Here, the heavy grinding brush roll is, as disclosed in Japanese Patent Laid-Open No. 4-315582, a rod-shaped body containing abrasive grains and having a diameter of 3 mm or more, which is a roll shaft and which has an axial circle through a spring material. Radial with respect to the circumference, in a brush roll mounted in a state gathered in the axial direction, the rod-shaped body and the grinding element body formed by the spring material connecting the rod-shaped body are arranged in a screw-like manner, and The angle between the surface and the surface of the threading element body is 3 degrees or more,
This is a heavy polishing brush roll in which each grinding element body is provided with an enormous portion for restricting the movement of the grinding element body in the adjacent direction, and has a polishing performance almost equal to that of a grinding stone or a polishing disk.

[0008]

According to the present invention, the surface oxide layer of the stainless steel strip after hot rolling is practically removed by a grinding brush roll or brought into a light scale state before annealing, so that the scale after annealing is thin and peels off. It will be easy. As a result, it is possible to reduce defects of scale residue after pickling, and it is possible to reduce indentation defects caused by rolls in the continuous annealing furnace in austenitic stainless steel.

[0009]

1 and 3 show an example of the arrangement of equipment used in the manufacturing method of the present invention, and FIG. 2 shows an example of the arrangement of equipment in a conventional manufacturing method. In the present invention, the hot rolled stainless steel strip coil 1 is first applied to the grinding brush roll 2 to substantially remove the scale layer, and then the austenitic stainless steel is continuously annealed in the furnace 4 shown in FIG.
It passed through a mechanical scale breaker 5, a shot blasting device 6 and a pickling equipment 7. On the other hand, the ferritic and martensitic stainless steels were treated in the batch annealing furnace 3 shown in FIG. 1 and then passed through a mechanical scale breaker 5, a shot blasting device 6 and a pickling equipment 7.

In the conventional example, the steel strip coil 1 after hot rolling
2, the austenitic stainless steel was treated in the continuous annealing furnace 4, and the ferritic and martensitic stainless steels were treated in the batch annealing furnace 3 as shown in FIG. It went through the same process as. FIG. 4 is a schematic diagram of a steel plate cross section showing a comparison of scales after annealing with a heavy grinding brush roll before annealing and a conventional one.

According to the present invention, since the scale after hot rolling is ground to reduce the emissivity, the scale after annealing has been successfully thinned. FIG. 5 shows the transition of the scale residual defect occurrence rate depending on the presence or absence of the oxide layer grinding by the heavy grinding brush roll before annealing. It can be seen that the scale remaining defect is drastically reduced after the grinding with the heavy grinding brush roll.

FIG. 6 shows changes in the rate of occurrence of defects in hearth roll defects depending on the presence or absence of grinding of an oxide layer by a heavy grinding brush roll before annealing. It can be seen that the defects in hearth roll defects have sharply decreased after the grinding with the heavy grinding brush.

[0013]

INDUSTRIAL APPLICABILITY According to the present invention, the scale layer after annealing can be thinned at a comparatively low cost by grinding the stainless hot-rolled steel sheet with a grinding brush roll before annealing. It was possible to reduce scale residue defects and roll defect defects in the furnace.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of equipment arrangement for carrying out the method of the present invention.

FIG. 2 is an explanatory diagram showing an example of a conventional equipment arrangement.

FIG. 3 is an explanatory view showing an example of equipment arrangement for carrying out the method of the present invention.

FIG. 4 is a steel plate cross-sectional view showing a comparison of scales after annealing with and without heavy grinding.

FIG. 5 is a graph showing changes in the scale remaining defect occurrence rate depending on the presence or absence of heavy grinding.

FIG. 6 is a graph showing changes in the defect rate of roll defects in a furnace depending on the presence or absence of heavy grinding.

[Explanation of symbols]

 1 Hot coil 2 Double grinding brush roll 3 Batch annealing furnace 4 Continuous annealing equipment 5 Mechanical scale breaker (MSB) 6 Shot blast 7 Pickling tank

 ─────────────────────────────────────────────────── ─── 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 (2)

[Claims] 1. A method for producing a stainless hot-rolled steel strip in which a hot-rolled stainless steel strip is subjected to batch annealing or continuous annealing, followed by continuous pickling, wherein the surface of the stainless hot-rolled steel strip is treated with a grinding brush roll before the annealing. A method for producing a stainless hot-rolled steel strip, which comprises grinding to substantially remove scale or light scale. 2. The method for producing a hot rolled stainless steel strip according to claim 1, wherein the grinding brush roll is a heavy grinding brush roll.