Method for producing high-strength thin strip steel in short process

Abstract

The invention relates to a method for producing high-strength thin strip steel in a short process. Twin roll strip casting is adopted for producing an atmospheric-corrosion-resistant steel casting belt containing a rare earth element Re, hot rolling, cooling and anti-oxidation intensive cooling scale removing are performed on the steel casting belt, and then the steel casting belt is reeled up after being straightened, wherein in the hot rolling process of the strip steel, rolling reduction is not smaller than 20%, and finishing rolling temperature is 850-1000 DEG C; then, a staged cooling mode of atomization cooling plus anti-oxidation intensive cooling ( spraying dry ice) is adopted, and intensive cooling is carried out on the high-temperature strip steel, wherein the cooling rate in the atomization cooling process is 50-100 DEG C / s, and the cooling rate in the anti-oxidation intensive cooling process is 100-200 DEG C / s. In this way, through the combined type staged cooling, the uniform steel of a bainite microscopic structure can be obtained, and the bainite structure can remarkably improve the toughness of the steel. The method is especially applicable to atmospheric-corrosion-resistant high-strength thin strip steel with the surface roughness Ra smaller than 2 microns, the thickness of typical strip steel is 0.8-1.6mm, and the strip steel can be supplied in a hot mode instead of a cool mode.

Description

technical field [0001] The invention relates to a continuous casting process, in particular to a short-flow method for producing high-strength thin strip steel. Background technique [0002] Traditional thin strips are mostly produced by multi-pass continuous rolling of cast slabs with a thickness of 70-200mm, while cast strips produced by twin-roll thin strip continuous casting process are rolled into hot strips in one or two passes. The rolled strip can be put into the market after dephosphorization treatment. Compared with the traditional strip production process, the former has a shorter production line and requires less energy. It is a low-carbon and environmentally friendly hot-rolled thin strip production process. [0003] The typical process flow of twin-roll thin strip continuous casting is as follows: figure 1 As shown, the molten steel in the ladle 1 is poured directly through the nozzle 2, the tundish 3 and the flow distributor 4 in a room surrounded by two rel...

AI Technical Summary

Problems solved by technology

However, how to control the thickness of the scale during the conveying process from the rolling mill to the coil is seldom covered by relevant patents, especially in the process of cooling the strip by laminar flow cooling or spray cooling, the high temperature strip is in contact with the cooling water , the thickness of the scale on the surface of the cast strip increases rapidly; at the same time, the contact between the high-temperature strip steel and the cooling water will cause many problems: first, water spots (rust spots) will be formed on the surface of the strip steel, which will affect the surface quality; The cooling water used for laminar cooling or spray cooling is likely to cause uneven local cooling on the surface of the strip, resulting in uneven microstructure inside the strip, resulting in uneven performance of the strip and affecting product quality; third, strip steel Partial cooling on the surface is not uniform, which will cause the deterioration of the shape of the plate and affect the quality of the shape of the plate

In addition, laminar flow cooling or spray cooling has limited cooling strength, and it is difficult to produce high-strength steel with a yield strength of 550MPa or more.

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