A Method for Reducing Water Ripple Defects on Steel Plate Surface

Abstract

The invention discloses a method for reducing water-like defects on the surface of a steel plate, which is characterized in that: the steel plate includes iron and the following components in mass percentage: C≤0.20%, Si: 0.25-0.60%, Mn≤2.0% , Ni ≤ 0.80%, Cr ≤ 0.80%, Mo ≤ 0.6%, Cu: ≤ 0.80%, and CEV ≤ 0.65%; the method includes heating, rolling, cooling process, by adopting conventional heating parameters, appropriately increasing the waiting temperature At the same time, the descaling blow pressure of the finishing mill is reduced from 20-22Mpa to 11-13Mpa, the surface oxide layer is removed, and the dense oxide layer is retained, so as to reduce the "water streak"-like defects on the steel plate surface. At the same time, this solution does not need to modify the equipment, which is simple and easy; it also enhances the corrosion resistance of the steel plate surface.

Description

technical field [0001] The invention belongs to the technical field of steel rolling, and in particular relates to a method for reducing water-marked defects on the surface of a steel plate. Background technique [0002] With the development of steel rolling technology, the corresponding auxiliary rolling technology has also been developed. For example, the removal process of the iron oxide scale generated when the steel surface is heated is the so-called descaling process. The scale pressure water is replaced, and the descaling pressure has developed from the initial 10Mpa to the current 25Mpa, and the development is very rapid. [0003] At present, the descaling pressure of mainstream steel mills is basically between 20-23Mpa, but the surface of the produced steel plate cannot avoid the "water pattern" defect, that is, after descaling, the iron oxide scale on the surface of the steel plate cannot be removed, resulting in descaling. After scaling, strip marks appear on the...

AI Technical Summary

Problems solved by technology

[0003] At present, the descaling pressure of mainstream steel mills is basically between 20-23Mpa, but the surface of the steel plate produced still cannot avoid the "water streak" defect, that is, after descaling, the iron oxide scale on the surface of the steel plate cannot be completely removed, resulting in descaling. There are strip marks on the surface of the scaled steel plate in the same rolling direction, and the depth of the defect is 0.02-0.15mm, which is usually not obvious to the naked eye, but it can be found similar to water ripples when illuminated by strong light from the side, which is usually distributed in strips. Especially in ordinary steel and low alloy high strength steel

At present, in order to solve this problem, major steel mills mainly adopt the following three methods: 1. Increase the starting temperature of finish rolling to reduce the generation of scale. This method needs to increase the starting temperature to above 860°C, but this will reduce the Intensity, it is necessary to increase the amount of alloy added or reduce the final cooling temperature, resulting in the bending of the steel plate; 2. Increase the pressure of descaling, this method needs to increase the pressure of phosphorus removal to above 25Mpa, and the equipment needs to be upgraded, which increases the cost; 3 , Change the chemical composition of the steel plate, this method uses low-silicon smelting, but this will increase the cost

[0004] In summary, there is no simple and economical solution for this defect in the prior art