Cooling method of high strength band steel and device

Abstract

The invention discloses a high-strength strip steel cooling device, which comprises: an entrance roller; an exit roller; High-concentration hydrogen cools the steel strip; several water-cooled stabilizing rolls are sequentially arranged on the running path of the strip to be cooled between the entrance roll and the exit roll, and the strip to be cooled passes through a set of water-cooled stabilizing rolls in turn and is cooled by water The stabilizing rolls are cooled, and the strip steel forms a wrap angle when passing through the water-cooled stabilizing rolls; among them, the water-cooling stabilizing rolls are arranged in pairs, and multiple high-hydrogen high-speed nozzles are arranged between every two pairs of water-cooling stabilizing rolls, and each water-cooling stabilizing roll The opposite side of the roller provides a high flow high hydrogen velocity nozzle. The cooling method of the present invention belongs to the dry cooling method, and the average cooling rate is as high as 200 / S°C (for 1.0mm steel strip), the cooling is uniform, and a good strip shape after rapid cooling can be guaranteed.

Description

technical field [0001] The invention relates to the field of heat treatment of iron and steel materials, and more specifically relates to a "dry" rapid cooling method for continuous annealing of strip steel or a hot-dip galvanizing production line. Background technique [0002] With the enhancement of people's awareness of environmental protection and the continuous improvement of driving safety requirements, the steel for automobiles is developing towards high strength. [0003] Generally speaking, high-strength cold-rolled sheets and hot-dip galvanized sheets are produced by continuous annealing units and hot-dip galvanizing units respectively. Must have rapid cooling capability (water quenching, high hydrogen high-speed jet cooling or roller cooling, etc.). The typical process flow of continuous annealing of high-strength cold-rolled sheet is: [0004] Uncoiling-cleaning-heating-soaking-slow cooling-rapid cooling-aging (tempering)-secondary cooling-low temperature water...

AI Technical Summary

Problems solved by technology

The main disadvantages of this patent are: in order to ensure the high-speed and stable pass-through of the strip, and to reduce the strong vibration of the strip, a high enough air jet velocity is not used, which reduces the cooling speed of the method. More importantly, due to the Vibration of steel is unavoidable, so stabilizing rolls must be installed to avoid surface scratches or even broken strips caused by violent vibration of the strip. The average cooling rate of the patented cooling method is lower than 150°C / S (for strip steel with a thickness of 1mm)

The main disadvantage of this patent is: since the roll cooling is mainly used, in order to improve the cooling capacity, the wrapping angle between the strip steel and the water-cooled roll has to be increased. When the high-temperature strip steel contacts with the low-temperature water-cooled roll, the whole It is difficult to evenly contact the contact arc section, so the cooling of the strip steel is uneven. Although increasing the tension can improve the contact condition, it cannot fundamentally solve the problem of uneven cooling. When the phase change occurs in the process, volume changes will occur, resulting in poor plate shape, which in turn aggravates the poor contact, which further aggravates the uneven cooling and leads to the deterioration of the plate shape. Therefore, the cooling method mainly based on roll cooling is It belongs to the "divergent" type of cooling method; moreover, the excessive tension in the rapid cooling section will deform the strip steel, and the thinner strip steel will produce a buckle, which will also deteriorate the strip steel shape; in terms of cooling rate, although the roll In the traditional cooling method, the local cooling rate in the contact section is very high (up to 300°C / S), but the cooling rate in the non-contact section is very small, so the average cooling rate is not high (80°C / S). The patented cooling method also adds air jet cooling to the back of the strip in contact with the water-cooled roll, which increases the cooling rate, but the strip between the water-cooled rolls does not have any cooling, so the average cooling rate is still low, which cannot fully meet the requirements. Requirements for rapid cooling in the production of phase transformation strengthened high strength steel

[0012] As can be seen from the above, the simple high-hydrogen high-velocity jet cooling method (H 2 -GJC) and the cooling method combined with pure roller cooling and gas jet cooling (RQ+GJC) have obvious disadvantages

The cooling method (RQ+GJC) combining roll cooling and gas jet cooling (RQ+GJC) is mainly characterized by roll cooling, which often leads to deterioration of plate shape and greatly reduces its cooling rate when cooling phase transformation strengthened high-strength steel; Hydrogen high-speed jet cooling method (H 2 -GJC) can not implement high-hydrogen jet cooling at the stabilizing rolls used to prevent the strip steel from vibrating strongly under high-speed jet conditions, nor implement other cooling methods, which also greatly reduces its average cooling rate

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