CN102145380B - Method for continuously casting clean molten steel in tundish - Google Patents

Abstract

The invention relates to a method for cleaning molten steel in a continuous casting tundish. The technical solution is: 1 to 4 air-permeable bricks (4) are arranged on the bottom (2) of the tundish (1), and 1 to 4 ultrasonic generators (3) are arranged on the outer side of the tundish (1) , each sonotrode (3) is located on the extension line of its corresponding ventilating brick (4), and the distance between each sonotrode (3) and the end of the corresponding ventilating brick (4) on the same side is 500-1200mm ; Before the tundish (1) is poured, argon gas is introduced through the breathable brick (4), the argon blowing flow rate is 10-50Nl/min, and the pressure is 0.10-0.20MPa; when the tundish (1) is poured, turn on the ultrasonic In the generator (3), the argon blowing flow rate is 20-120 Nl/min, and the pressure is 0.15-0.30 MPa. The invention is beneficial for degassing and removing a large amount of tiny non-metallic inclusions, can reduce the inclusions in molten steel to a very low level, has no slag entrainment in molten steel, and has uniform and stable temperature; at the same time, it also has the advantages of less investment, portable equipment and simple operation , stable steel quality and other advantages.

Description

A method for cleaning molten steel in continuous casting tundish

technical field

The invention belongs to the technical field of steelmaking and continuous casting. In particular, it relates to a method for continuous casting tundish with clean molten steel.

Background technique

High-quality clean steel refers to the steel whose inclusions in the steel are reduced to the extent that they have no adverse effects on the processing performance and serviceability of the product. In recent years, with the development of national defense, transportation, and energy industry, its demand has been increasing continuously, and it has become an important direction for the development of world steelmaking technology in the new century. Developed countries are vying to possess the cutting-edge technology of clean steel smelting with a strategic position.

Improving the cleanliness of molten steel is the basis for improving steel quality. The removal of impurities such as [O], [H], [N] and non-metallic inclusions in steel that have a greater negative impact on steel performance has become a steelmaking process. An important link in the production of high-quality steel grades. Therefore, it is of great practical significance to improve and enhance the smelting level of converter-secondary refining-continuous casting in the steelmaking process.

With the development of continuous casting technology, the continuous casting tundish is the last chance to control the inclusions in the steel before the molten steel becomes a product. People have studied various tundish metallurgical technologies, such as changing the structure of the tundish, setting various baffles Flow control means such as walls, turbulence controllers, and high calcium filters effectively promote the floating of larger (greater than 50 μm) non-metallic inclusions in molten steel. In recent years, scientists and technicians have also developed argon blowing technology in the tundish, but it is limited to the size and distribution of bubbles, and the removal rate of small non-metallic inclusions smaller than 50 μm is still low, and will lead to a drop in molten steel temperature, high energy consumption, and production. low efficiency.

At present, high-quality steel products have very strict requirements on the particle size of oxide inclusions. For example, low-carbon aluminum-killed steel for DI cans with a thickness of 0.2-0.3mm, in order to prevent cracks when flushing cans, the particle size of inclusions in the steel is required Less than 40μm; engine valve spring steel requires inclusions to be less than 15μm in size; and ultra-thin strip steel for high anti-magnetic shadow masks for picture tubes with a thickness of only 0.1-0.2μm and steel wires for radial tires with a diameter of 0.1-0.25mm require inclusions The diameter is less than 5 μm. However, it has not yet been able to efficiently and stably achieve the above goals.

Contents of the invention

The invention aims to overcome the defects of the prior art, and aims to provide a method for cleaning molten steel in a continuous casting tundish with less investment, simple operation, high-efficiency degassing and large removal of fine non-metallic inclusions.

In order to achieve the above object, the technical solution of the present invention is: 1 to 4 air-permeable bricks are arranged at the bottom of the tundish, and 1 to 4 ultrasonic generators are correspondingly arranged on the side outside the tundish, and each ultrasonic generator They are respectively located on the extension lines of the respective corresponding air-permeable bricks, and the distance between each ultrasonic generator and the end face on the same side of the respective corresponding air-permeable bricks is 500-1200 mm.

Before the tundish is poured, argon is blown through the breathable brick (introducing argon gas), the argon blowing flow rate is 10-50Nl/min, and the argon blowing pressure is 0.10-0.20MPa; when the tundish is poured, turn on the ultrasonic generator, The flow rate of argon blowing is 20-120Nl/min, and the pressure of argon blowing is 0.15-0.30MPa.

In the above technical solution: the breathable brick is one of diffused breathable bricks, straight through slit breathable bricks, straight through hole breathable bricks, and combined breathable bricks; the ultrasonic frequency output by the ultrasonic generator 3 is 20-80KHz.

Due to the adoption of the above-mentioned technical scheme, the present invention has the advantages that several ultrasonic generators are arranged on one side outside the tundish without adding other equipment, so the investment is small and the operation is simple; The extension line of the breathable brick will form an ultrasonic action area above the breathable brick. When a large amount of inert gas is blown into the molten steel through the breathable brick, a large number of bubbles will be generated after the gas enters the molten steel. When the bubbles are in the ultrasonic action area, there is a large fluctuation velocity gradient on the bubbles, and the shear force generated by it It can break the bubbles into 0.5-1mm or even smaller micro-bubbles, and the gas-liquid interface between the micro-bubbles and molten steel is wrinkled due to the action of ultrasonic waves, and can more efficiently absorb and remove tiny inclusions below 40 μm or even 10 μm; ultrasonic air The chemical reaction can remove the impurity gas in the molten steel, especially the [H] which has a great influence on the performance of the steel, and its precipitation forms tiny bubbles to float the inclusion particles, which is also conducive to the collision and growth of the inclusion particles. Float up and remove, and at the same time, the blown normal temperature gas can neutralize the energy released by the ultrasonic wave, which also avoids the cooling of molten steel caused by blowing.

Therefore, the present invention is used in tundish clean steel smelting, which is beneficial to degassing and removing a large number of tiny non-metallic inclusions, and can reduce the inclusions in molten steel to a very low level, and the molten steel has no slag entrainment, and the temperature is uniform and stable; at the same time, It also has the advantages of less investment, light equipment, simple operation, and stable steel quality.

Description of drawings

Fig. 1 adopts a kind of structural representation of ultrasonic generator (3) for the present invention;

Fig. 2 adopts a kind of structural representation of two supersonic generators (3) for the present invention;

Fig. 3 adopts a kind of structural representation of three ultrasonic generators (3) for the present invention;

Fig. 4 is a schematic structural view of four ultrasonic generators (3) used in the present invention.

Detailed ways

Below in conjunction with specific implementation and accompanying drawing, the present invention will be further described, not limiting the scope of protection:

Example 1

The invention relates to a method for cleaning molten steel in a continuous casting tundish. As shown in Figure 1, a breathable brick (4) is arranged on the bottom (2) of the tundish (1), and an ultrasonic generator (3) is arranged on the outer side of the tundish (1), and the ultrasonic wave generates The device (3) is located on the extension line of the ventilation brick (4), and the distance between the ultrasonic generator (3) and the end face of the same side of the ventilation brick (4) is 500-700mm.

Before the tundish (1) is poured, argon gas (i.e. argon blowing) is introduced through the breathable brick (4), the flow rate of the argon blowing is 10-30Nl/min, and the pressure of the argon blowing is 0.17-0.20MPa; the tundish (1) When pouring is started, the ultrasonic generator (3) is turned on again, the argon blowing flow rate is 20-60Nl/min, and the argon blowing pressure is 0.20-0.26MPa.

In Embodiment 1: the air-permeable brick (4) is a diffuse air-permeable brick; the ultrasonic frequency output by the ultrasonic generator (3) is 20-35KHz.

Example 2

The invention relates to a method for cleaning molten steel in a continuous casting tundish. As shown in Figure 2, two air-permeable bricks (4) are arranged on the bottom (2) of the tundish (1), and two ultrasonic generators (3) are correspondingly arranged on one side outside the tundish (1), The two ultrasonic generators (3) are respectively located on the extension lines of the respective corresponding air bricks (4), and the distances between the two ultrasonic generators (3) and the ends of the corresponding air bricks (4) on the same side are both 700~ 900mm;

Before the tundish (1) is poured, argon gas (i.e. argon blowing) is introduced through the air-permeable brick (4), the argon blowing flow rate is 20-40Nl/min, and the argon blowing pressure is 0.14-0.17MPa; the tundish (1) When pouring is started, the ultrasonic generator (3) is turned on again, the argon blowing flow rate is 40-80Nl/min, and the argon blowing pressure is 0.18-0.23MPa.

In Embodiment 2: the air-permeable brick (4) is a straight-through slit-type air-permeable brick; the ultrasonic frequency output by the ultrasonic generator (3) is 35-50KHz.

Example 3

The invention relates to a method for cleaning molten steel in a continuous casting tundish. As shown in Figure 3, three air-permeable bricks (4) are arranged on the bottom (2) of the tundish (1), and three ultrasonic generators (3) are correspondingly arranged on one side outside the tundish (1), The three ultrasonic generators (3) are respectively located on the extension lines of the corresponding air bricks (4), and the distances between the three ultrasonic generators (3) and the end faces of the corresponding air bricks (4) on the same side are all 900~ 1100mm;

Before the tundish (1) is poured, argon gas (i.e. argon blowing) is introduced through the breathable brick (4), the flow rate of the argon blowing is 30-50Nl/min, and the pressure of the argon blowing is 0.10-0.15MPa; the tundish (1) When pouring is started, the ultrasonic generator (3) is turned on again, the flow rate of argon blowing is 60-100Nl/min, and the pressure is 0.15-0.19MPa.

In Embodiment 3: the air-permeable brick (4) is a through-hole air-permeable brick; the ultrasonic frequency output by the ultrasonic generator (3) is 50-65KHz.

Example 4

The invention relates to a method for cleaning molten steel in a continuous casting tundish. As shown in Figure 4, four air-permeable bricks (4) are arranged on the bottom (2) of the tundish (1), and four ultrasonic generators (3) are correspondingly arranged on one side outside the tundish (1), The four ultrasonic generators (3) are respectively located on the extension lines of the respective corresponding air-permeable bricks (4), and the distances between the four ultrasonic generators (3) and the end of the same side of the respective corresponding air-permeable bricks (4) are all 1000~ 1200mm;

Before the tundish (1) is poured, argon gas (i.e. argon blowing) is introduced through the air-permeable brick (4), the argon blowing flow rate is 20-40Nl/min, and the argon blowing pressure is 0.12-0.15MPa; the tundish (1) When pouring is started, the ultrasonic generator (3) is turned on again, the flow rate of argon blowing is 80-120Nl/min, and the pressure is 0.24-0.30MPa.

In Embodiment 4: the air-permeable brick (4) is a combined air-permeable brick; the ultrasonic frequency output by the ultrasonic generator (3) is 65-80KHz.

This specific embodiment is provided with 1～4 supersonic generators (3) on the side outside the tundish (1), without adding other equipment, so the investment is small and easy to operate; and because each supersonic generator (3) They are respectively located on the extension lines of the respective corresponding air bricks (4), and an ultrasonic action area will be formed above the air bricks (4). When a large amount of inert argon gas is blown into the molten steel through the breathable brick (4), a large number of bubbles will be generated after the gas enters the molten steel. The shear force can break the air bubbles into 0.5-1mm or even smaller micro-bubbles, and the gas-liquid interface between the micro-bubbles and molten steel is wrinkled due to the action of ultrasonic waves, which can more efficiently absorb and remove micro-inclusions below 40 μm or even 10 μm matter; ultrasonic cavitation can remove impurity gas in molten steel, especially [H] which has a great influence on the performance of steel, and its precipitation forms tiny bubbles to float inclusion particles, which is also beneficial to the removal of inclusion particles The collision grows up and floats up to remove. At the same time, the blown normal temperature gas can neutralize the energy released by the ultrasonic wave, which also avoids the cooling of the molten steel caused by the blowing.

Therefore, the present invention is used in tundish clean steel smelting, which is beneficial to degassing and removing a large number of tiny non-metallic inclusions, and can reduce the inclusions in molten steel to a very low level, and the molten steel has no slag entrainment, and the temperature is uniform and stable; at the same time, It also has the advantages of less investment, light equipment, simple operation, and stable steel quality.

Claims (3)

1. A method for cleaning molten steel in a continuous casting tundish, characterized in that 1 to 4 air-permeable bricks (4) are arranged on the bottom (2) of the tundish (1), and on the outer side of the tundish (1) Correspondingly, 1 to 4 ultrasonic generators (3) are provided, and each ultrasonic generator (3) is located on the extension line of the respective corresponding air-permeable brick (4), and each ultrasonic generator (3) is connected to the respective corresponding The distance between the ends of the same side of the air brick (4) is 500-1200mm; Before the tundish (1) is poured, argon gas is introduced through the permeable brick (4), the argon blowing flow rate is 10-50Nl/min, and the argon blowing pressure is 0.10-0.20MPa; when the tundish (1) is poured, the Turn on the ultrasonic generator (3), the argon blowing flow rate is 20-120 Nl/min, and the argon blowing pressure is 0.15-0.30 MPa. 2. The method for cleaning molten steel in continuous casting tundish according to claim 1, characterized in that said air-permeable brick (4) is a diffused-type air-permeable brick, a straight-through slit-type air-permeable brick, a straight-through hole-type air-permeable brick, a combination One of the air-permeable bricks. 3. The method for cleaning molten steel in a continuous casting tundish according to claim 1, characterized in that the ultrasonic frequency output by the ultrasonic generator (3) is 20-80KHz.

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