Water quenching method for producing cold rolling phase transition reinforced high strength strip steel

Abstract

The invention discloses a water quenching method for producing a cold rolling phase transition reinforced high strength strip steel, which is characterized in that a further rapid cooling process is carried out on the strip steel after the strip steel is subjected to annealing and slow cooling. The method comprises the following steps: 1) using a first injection apparatus to inject layered water column to the surface of the strip steel, wherein the included angle of the layered water column injection direction and the strip steel moving direction presents an acute angle; 2) using a second injection apparatus to inject the high speed water flow to the strip steel surface, blowing the steam bubbles and vapor films on the strip steel surface away by the high speed current; 3) soaking the strip steel in cooling water, using a third injection apparatus provided under the liquid surface of the cooling water to inject high speed water flow to the strip steel surface, blowing the steam bubbles and vapor films on the strip steel surface away by the high speed current; and 4) drying the cooling water on the strip steel surface.

Description

technical field [0001] The invention relates to a cooling method for cold-rolled steel strips, in particular to a water-quenching cooling method for cold-rolled steel strips. Background technique [0002] In order to produce high-strength steel plates, especially ultra-high-strength steel plates, by adding a small amount of alloying elements to the base plate of the steel plate, in order to improve the weldability and manufacturability of the steel plate (including easy casting, hot rolling, trimming, cold rolling, annealing) and other process production), for the continuous annealing unit, the rapid cooling treatment is usually carried out after the slow cooling section of the strip annealing. At present, the commonly used rapid cooling methods include high hydrogen jet cooling, gas mist cooling and water quenching cooling. [0003] High hydrogen jet cooling has the following disadvantages due to the use of high-concentration hydrogen as the cooling medium: [0004] (1) B...

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Problems solved by technology

[0004] (1) Because high-hydrogen is prone to explosion, high-hydrogen jet cooling has great potential safety hazards;

[0005] (2) Because all equipment and instruments in the high-hydrogen jet cooling section need to be explosion-proof, the investment is greatly increased. In addition, because the hydrogen consumption is large during production, not only the production cost is high, but also a supporting hydrogen production station is often required to be built. Therefore, relatively speaking, the investment and production costs of high-hydrogen jet cooling are high;

[0006] (3) When the plate shape is bad, such as buckling, it must be shut down for processing during the production process, resulting in unstable production and seriously affecting the production capacity of the unit

This is because the atmosphere of the high hydrogen jet cooling section is different from the atmosphere of other sections of the furnace (the hydrogen content is very different), in order to separate the high hydrogen cooling section from the slow cooling section, the soaking section and the subsequent processing section, it is necessary to separate the high hydrogen cooling section The hydrogen injection cooling section is strictly sealed (usually with sealing rollers and other measures). Once the plate shape such as buckling occurs, due to the small gap between the sealing rollers, in order to achieve the sealing effect, the sealing rollers cannot be opened at this time and must be shut down. Otherwise, belt breakage will occur, which will cause unstable production and seriously affect the production capacity of the unit;

[0007] (4) The cooling capacity is relatively low, and the cooling rate of high hydrogen injection cooling is usually lower than 150°C / s (for strip steel with a thickness of 1.0mm)

This method is more suitable for the rapid cooling of low-temperature strip steel, which can cool the strip steel at about 400°C to below 60-95°C, but has the following disadvantages: (1) The scope of application is narrow, and it is only suitable for water quenching of low-temperature strip steel Production, it is difficult to apply high-temperature water quenching (cool the strip steel at about 700 °C to below 90 °C at normal production speed); (2) The water mist and water vapor generated by cooling the strip steel can easily enter the front furnace , so that the equipment is seriously corroded; (3) where the spray cooling starts, the spray cooling water is easy to splash, resulting in uneven cooling of the strip and poor shape

Due to the high temperature of boiling water (temperature above 100°C), the cooling rate cannot reach the cooling rate of cold water quenching, and the surface oxidation of the strip is also more serious, and the subsequent pickling is also more difficult, resulting in higher production costs.

[0012] In addition, the various existing water quenching methods cannot ensure that when the water quenching starts, the strip steel will evenly contact the cooling water for cooling.

When the traditional quenching tank is used for immersion cooling, the water vapor produced by water quenching will produce a large amount of water splashes at the beginning of water quenching and the vibration of the strip steel will cause liquid level fluctuations, resulting in different contact times for the strip steel at the beginning of water quenching. As a result, there is a difference in the cooling rate, resulting in poor shape of the water-quenched strip, and the higher the strength of the strip, the worse the shape

When the traditional spray cooling is used, the sprayed cooling water splashes after the strip rebounds, and continuously touches the strip before water quenching, which also causes uneven cooling speed of water quenching, and cannot guarantee the strip steel to obtain excellent shape

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