Dual-descaling method for hot rolling strip steel slab

Abstract

The invention relates to a dual-descaling method for a hot rolling strip steel slab, which comprises the following steps of: aslant and outwards spraying descaling water by a nozzle of a descaling water spraying pipe installed on an inlet and outlet of a rough mill; and removing mill scale on the surface of the strip steel slab, and cooling the strip steel slab. The dual-descaling method is characterized in that a plurality of rows of drooping water blockage chains installed on the inlet and outlet of the rough mill are used for blocking spraying descaling water when the descaling water is sprayed; a water pipe arranged on the inlet and outlet of the rough mill is used for carrying out spraying high-pressure water aslant and inwards in a back flushing way when pressure intensity is less than 19MPa; back flushing water is sprayed to the descaling water spraying position on the surface of the strip steel slab; the back flushing water is used for blocking descaling water escaped along the surface of the strip steel slab; the flow of the back flushing water is 2/9-4/9 of that of the descaling water; the descaling water spraying angle relative to the horizontal plane is 75-85 degrees; and the flushing water spraying angle relative to the horizontal surface is 42-48 degrees. The dual-descaling method for the hot rolling strip steel slab has the capability of reducing the defect rate.

Description

technical field [0001] The invention relates to a double descaling method for a hot-rolled strip steel slab. Background technique [0002] When the 2250mm production line of the applicant's hot rolling mill produces high-strength steel such as pipeline steel, the problem of scarring and cracking at the head and tail of the strip occurs continuously, especially the tail is more serious. For example, the defect rate in April 2009 was 25.71%, which could not meet the user's requirements and could only be processed by cutting, resulting in a cutting loss rate of 4.23%. [0003] Many times on-site observations found that when rolling pipeline steel, in order to ensure the RDT temperature, a double descaling process was adopted in each pass, and the descaling water escaped along the surface of the strip slab many times, resulting in a large temperature drop on the surface of the strip slab , at the same time, due to the tilting phenomenon of the head and tail of the strip steel s...

AI Technical Summary

Problems solved by technology

For example, the defect rate in April 2009 was 25.71%, which could not meet the requirements of users, and could only be processed by cutting, resulting in a cutting loss rate of 4.23%.

[0003] Many observations on site found that when rolling pipeline steel, in order to ensure the RDT temperature, a double descaling process was adopted in each pass, and the descaling water escaped along the surface of the strip slab many times, resulting in a large temperature drop on the surface of the strip slab , at the same time, due to the tilting phenomenon of the head and tail of the strip steel slab, which are washed by cooling water, the head and tail of the strip steel slab are cooled and blackened in large areas, and the ductility is poor. During the continuous rolling process, the surface of the head and tail of the strip steel slab scar cracking

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