A method for eliminating mottled defects on the surface of hot-rolled steel plates

Abstract

A method for eliminating mottled defects on the surface of a hot-rolled steel plate, relating to a method for treating the surface of a steel plate, the method comprising the following process: heating the slab to 1200-1250°C, and then descaling with high-pressure water, and the descaling temperature is 1100°C ~1200°C, the water pressure is required to be at least 16MPa during descaling; the steel plate after descaling is subjected to rough rolling, and the rough rolling temperature is 1100~1200°C; the rough rolled steel plate is subjected to finish rolling, and the finishing rolling temperature is 900~990℃, the speed of the roller table is 1.3~1.8m / s; after finishing rolling, laminar flow cooling is adopted for water cooling, and segmental cooling is adopted, the water ratio is 2.2~2.6; the cooling water volume is 150~250m³ / h; the reddening temperature of the steel plate after cooling is 670~750°C; the water-cooled steel plate is cooled in the air on the cooling bed. The method makes it easy to remove the iron oxide scale on the surface of the steel plate in the subsequent shot blasting process, thereby eliminating the mottled defect on the surface of the steel plate after shot blasting.

Description

technical field [0001] The invention relates to a steel plate surface treatment method, in particular to a method for eliminating mottled defects on the surface of a hot-rolled steel plate. Background technique [0002] The hot-rolled steel plate will produce a layer of oxide scale on the surface of the steel plate during the rolling process. Under different hot rolling conditions, the structure and thickness of the obtained iron oxide scale are changed. Hot-rolled sheets are playing an increasingly important role in the national economy, but the main concern is performance quality and dimensional accuracy. Surface quality has become a common problem in the industry that restricts the overall quality of hot-rolled sheets in my country. Due to the long-term lack of attention to the surface quality of hot-rolled steel products, these products often have problems such as red rust, pits and pits due to improper control of the surface iron sheet, causing many quality objections ...

AI Technical Summary

Problems solved by technology

Chinese Patent Application No. 200710010183.5 "Medium and Thin Slab Continuous Casting and Rolling Strip Steel Surface Scale Control Method" provides the scale for medium and thin slab hot-rolled strip steel including composition design, descaling process, rolling and cooling process The control method is mainly aimed at the short-process production line of medium and thin slabs, and the main solution is how to remove the red rust on the surface. It does not mention how to eliminate the color difference defects after shot blasting on the surface of the steel plate

Chinese Patent Application No. 201010010116.5 "A Method for Detecting Scale Structure of Hot-Rolled Strip Steel by Chemical Corrosion" provides a chemical detection method for detecting the scale structure of hot-rolled strip steel, which is useful for controlling the structure and thickness of scale on the surface of steel plates wait did not introduce

Chinese Patent Application No. 201010189410.7 "Flexible Control Method of Scale on Hot-rolled Strip Surface" provides a method for controlling the structure and adhesion of scale on the surface of steel strip in a hot-rolled production line. Different processing characteristics are shown in the deep processing process. How to require different structure of iron oxide scale according to the deep processing process characteristics of downstream production enterprises (whether there is an oiling process) does not involve how to eliminate the surface defects of the steel plate

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