High-pulling-speed continuous casting production method for hot-rolled ribbed steel bars

Abstract

The invention discloses a high-pulling-speed continuous casting production method for hot-rolled ribbed steel bars. The method comprises the steps of converter smelting and continuous casting. In the converter smelting step, an Si-A1 deoxidizing agent is adopted, and the average active oxygen of molten steel is controlled to be 35 ppm or below; in the continuous casting step, a low-carbon tundish covering agent is used in the whole process, 210-270 kg of the low-carbon covering agent is used in a first furnace for casting, 70-90 kg of the low-carbon covering agent is used on each of the two sides of the tail of a tundish, and 70-90 kg of the low-carbon covering agent is used in an impact area of the tundish; the two sides of the tundish tail of the second furnace are each 40-60 kg, and the impact area of the tundish is 40-60 kg; the weight of each of the two sides of the tundish tail of the third furnace is 20-40 kg, and the weight of each tundish impact area is 20-40 kg; 3-5 kg of the materials are added to the two sides of the tail of the tundish and the impact area of the tundish in each subsequent furnace; the liquid level is controlled to be 900-1100 mm in the whole pouring process, and the thickness of a tundish slag layer is smaller than or equal to 80 mm; the tundish impact area adopts a porous U-shaped retaining wall design; and the tundish stuffing sand is added in a sand adding mode before baking. According to the method, the problems of diameter expansion and nodulation of the zirconium core of the upper nozzle can be effectively reduced, and the service time of the upper nozzle can be effectively prolonged.

Description

Technical Field

[0001] The invention relates to a continuous casting and rolling method, in particular to a high-speed continuous casting production method for hot-rolled ribbed steel bars. Background Art

[0002] The direct rolling process organizes production around continuous casting and direct bar rolling, requiring the continuous casting cycle to match the rolling mill's product change, roll change, and slot change. This requires the continuous casting machine to have a continuous high-speed production capacity of 50 to 60 hours under high-speed conditions. At present, the diameter expansion and nodule formation of the tundish nozzle often occur at a speed of 4.5 to 5 m / min, which seriously limits the service life of the nozzle.

[0003] The main core part of the tundish upper nozzle is the zirconium core. Generally, the zirconium core is a zirconium oxide material stabilized by magnesium oxide and yttrium oxide or calcium oxide and yttrium oxide, which is a metastable material. Zirconium oxide has the characteristics of small thermal conductivity and large thermal expansion coefficient, which determines that the zirconium core material has poor resistance to rapid cooling and heating. The upper nozzle is easy to expand and peel off during the pouring process, resulting in nodule formation, which restricts the service life of the upper nozzle.

[0004] At present, the slag discharge in the ladle is serious and the slag discharge frequency in the tundish is small. With the increase of the pouring time of the tundish, the amount of slag in the tundish will increase. The thickness of the slag layer is generally 300mm. Under the high pulling speed of 4.5-5m / min, the fine slag in the molten steel is easy to adhere to the rough zirconium core, which will aggravate the corrosion of the zirconium core and thus cause nodule phenomenon.

[0005] The traditional quick-change tundish repair method is a combination of a flow stabilizer and a "V"-shaped retaining wall. The slag in the molten steel has a short floating time, is easy to fall, and cannot be effectively removed. At the same time, the tundish liquid level is not stable, causing the static pressure at the upper water inlet to fluctuate, which will also damage the upper water inlet zirconium core. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a high-speed continuous casting production method for hot-rolled ribbed steel bars which can effectively reduce the problems of diameter expansion and nodule formation of zirconium core at the upper water inlet.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: comprising converter smelting and continuous casting steps; The converter smelting step: using Si-A1 deoxidizer to control the average active oxygen content of molten steel to 35ppm or less; The continuous casting steps include: using a low-carbon tundish covering agent throughout the entire process, using 210-270kg of low-carbon covering agent for the first casting, 70-90kg on each side of the tundish tail and 70-90kg in the tundish impact zone; using 40-60kg on each side of the tundish tail and 40-60kg in the tundish impact zone for the second casting; using 20-40kg on each side of the tundish tail and 20-40kg in the tundish impact zone for the third casting; adding 3-5kg on each side of the tundish tail and in the tundish impact zone for each subsequent casting; controlling the liquid level to 900mm-1100mm throughout the casting process, and having a tundish slag layer thickness of ≤80mm; adopting a porous U-shaped retaining wall design in the tundish impact zone; and adding drainage sand to the tundish by adding sand before baking.

[0008] Furthermore, in the continuous casting step, the tundish pouring temperature is greater than 1200°C.

[0009] Furthermore, in the continuous casting step, the tundish baking is performed in stages: based on the start of heating time, the temperature is raised to 300°C within 30 minutes, then raised to 800-1100°C in the first 30 minutes to 4 hours, and then raised to 1150-1350°C; the total time for tundish baking is 5.5-6 hours.

[0010] Furthermore, in the continuous casting step, the continuous casting speed is controlled at 4.5 m / min to 5 m / min, and the tundish temperature is controlled at a target of liquidus temperature + (10 to 25)°C.

[0011] Furthermore, the continuous casting step: uses a low-carbon tundish covering agent with a basicity of 1.30-1.50 and a viscosity of 0.145-0.150 Pa·1300°C.

[0012] Furthermore, the porous U-shaped retaining wall structure includes a retaining wall body, upper holes on the retaining wall, lower holes on the retaining wall and an overflow trough; the horizontal cross-section of the retaining wall body is a U-shaped structure, consisting of a middle wall and two side walls; overflow troughs are provided on the tops of the two side walls; and retaining wall upper holes and lower holes on the retaining wall that penetrate the wall body are provided on the two side walls.

[0013] Furthermore, the lower hole of the retaining wall is located at the lower part of the side wall, and the upper hole of the retaining wall is located at the lower middle part of the side wall.

[0014] Furthermore, the lower holes of the retaining wall are arranged in a row of two, and the upper holes of the retaining wall are arranged in a row of two.

[0015] Furthermore, the lower hole of the retaining wall and the upper hole of the retaining wall are both inclined with the inner side lower and the outer side higher. Furthermore, the angle between the lower hole of the retaining wall and the horizontal plane is 15-25°, and the angle between the upper hole of the retaining wall and the horizontal plane is 15-25°.

[0016] The beneficial effects of adopting the above technical solution are: (1) Deoxidizer: Due to the presence of Ca in Si-A1-Ca deoxidizer, the density of the deoxidizer is relatively small. When added to the molten steel for deoxidation, it floats on the surface of the molten steel and cannot react well with the oxygen in the molten steel to play a deoxidation role. The Al content in Si-A1-Ca deoxidizer is lower than that in Si-A1. Under the premise of the same addition amount, it cannot play a good deoxidation role. Under the premise of the same addition amount, the deoxidation effect of Si-A1 deoxidizer is better than that of Si-A1-Ca deoxidizer. Reducing the active oxygen in the molten steel reduces the erosion of the oxygen element in the steel on the zirconium core of the nozzle.

[0017] (2) Design of low-carbon covering agent and slag retaining wall: Under high pulling speed conditions, the impact kinetic energy of molten steel increases, the flow rate of molten steel increases, and the scouring of the water inlet of the tundish is more serious. Adding a slag retaining wall can slow down the physical scouring of the water inlet by molten steel. At the same time, the slag retaining wall can improve the flow field of the tundish and promote the floating of steel inclusions. The low-carbon covering agent can adsorb the floating inclusions to achieve the purpose of removing the inclusions. At the same time, low-carbon inclusions have requirements on carbon content and will not affect the composition of molten steel.

[0018] (3) Tundish baking and sand adding method: The expansion and cracking of the zirconium core of the tundish upper nozzle are related to the zirconium core of the nozzle. The main component of the zirconium core of the upper nozzle is ZrO2, and a small amount of MgO, ethylene trioxide (Y2O3) and other rare earth stabilizers are added. The binder is generally polyvinyl alcohol. When the temperature changes, zirconium oxide will produce a phase structure transformation of monoclinic, tetragonal and cubic systems. There is a volume change in this process. Therefore, the thermal shock resistance of zirconium oxide is very poor. As the continuous casting speed increases, the erosion of the zirconium core of the upper nozzle increases due to poor thermal shock resistance, and the more chaotic the flow field of the molten steel is, the more directly it washes the zirconium core of the upper nozzle, and the nozzle expands seriously, which brings greater risks to the safety of continuous casting. By optimizing the tundish baking and sand adding method, the baking temperature of the zirconium core of the upper nozzle can be increased, and the thermal shock stability of the zirconium core of the upper nozzle can be improved.

[0019] The present invention can effectively reduce the problems of diameter expansion and nodule formation of the zirconium core at the upper water inlet. By optimizing the deoxidizer, the oxygen content in the steel is reduced, and the oxidation of the zirconium core is reduced. The low-carbon covering agent and slag retaining wall design effectively improve the flow field of the tundish, and improve the efficiency of floating and removing inclusions in the molten steel. By improving the tundish baking and sand adding methods, the baking temperature of the upper water inlet is increased, and the zirconium core material is prevented from peeling off due to poor resistance to rapid cooling and heating, further reducing the risk of the zirconium core at the upper water inlet from bursting and reducing the occurrence of nodules.

[0020] The present invention can effectively increase the service life of the water inlet. It realizes the production requirement of long-life tundish casting time at high drawing speed, and further reduces the production cost. The casting time is increased by reducing the problems of diameter expansion and nodule formation of the zirconium core of the water inlet. The average casting time of the tundish reaches more than 60 hours, and the maximum casting time reaches 70 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] Figure 1 It is the main schematic diagram of the porous U-shaped retaining wall of the present invention; Figure 2 is a side view of the porous U-shaped retaining wall of the present invention; Figure 3 is a top view of the porous U-shaped retaining wall of the present invention; Figure 4 yes Figure 3 AA view in .

[0023] In the figure: retaining wall body 1, lifting ring 2, upper hole of retaining wall 3, lower hole of retaining wall 4, overflow trough 5. DETAILED DESCRIPTION

[0024] The high-speed continuous casting production method of hot-rolled ribbed steel bars adopts the following process: 1. This method is suitable for low alloy steels, especially HRB400 series, HRB500 series and HRB600 series of continuous casting and direct rolling threaded steel bars. The pulling speed is controlled at 4.5m / min to 5m / min, and it is stable and uniform. The casting section is 150mm×150mm to 165mm×165mm. The tundish temperature control target is: liquidus temperature +10℃ to liquidus temperature +25℃. For example, the liquidus temperature of HRB400 series steel is 1505℃, and the tundish temperature control target is 1515~1530℃.

[0025] 2. The converter uses Si-A1 deoxidizer instead of Si-A1-Ca agent, and adds 25-75kg / furnace according to the end point C. The higher the end point carbon content, the lower the amount added. It is best to add 60-75kg / furnace for C < 0.05wt%, 40-60kg / furnace for 0.08> C ≥ 0.05wt%, and 25-40kg / furnace for C ≥ 0.08wt% to improve the deoxidation strength, reduce the average active oxygen of molten steel from 43ppm to 35ppm and below, and reduce the erosion of oxygen elements in steel on the zirconium core of the nozzle.

[0026] 3. Use low-carbon tundish covering agent throughout the whole process. For the first furnace, use 210-270kg of low-carbon covering agent, 70-90kg on both sides of the tundish tail, and 70-90kg in the tundish impact zone; for the second furnace, use 40-60kg on both sides of the tundish tail, and 40-60kg in the tundish impact zone; for the third furnace, use 20-40kg on both sides of the tundish tail, and 20-40kg in the tundish impact zone; observe the liquid level protection situation for each subsequent furnace, and add 3-5kg on both sides of the tundish tail and the tundish impact zone as appropriate.

[0027] 4. Low-carbon tundish covering agent, with a basicity of 1.30-1.50, a viscosity of 0.145-0.150 Pa·1300℃, and a carbon content ≤3wt%.

[0028] 5. Applicable to multi-stream billet continuous casting machine, the tundish is a "T" type structure, the tundish is a quick-change tundish, the capacity is 45t~90t, and the liquid level is controlled at 900mm~1100mm during the whole casting process. The ladle does not drop slag, the ladle does not hold slag, the ladle is closed when slag is seen, and the slag layer thickness of the tundish is ≤80mm. The slag layer thickness of the tundish is measured for each furnace.

[0029] 6. The impact area of ​​the tundish adopts a porous U-shaped retaining wall design. Figure 1-4 As shown, the porous U-shaped retaining wall structure includes a retaining wall body 1, retaining wall upper holes 3, retaining wall lower holes 4 and an overflow trough 5. The retaining wall body 1 has a U-shaped structure in horizontal section, which is composed of a middle wall and two side walls integrally designed on both sides of the middle wall. The tops of the two side walls are each provided with an overflow trough 5, and the overflow trough 5 is arranged at one end of the side wall close to the middle wall. The retaining wall upper holes 3 and the retaining wall lower holes 4 that penetrate the wall body are provided on both side walls; the retaining wall upper holes 3 are provided on each side wall, located in the middle and lower part of the side wall, and are respectively located on both sides directly below the overflow trough 5 of the side wall; the retaining wall lower holes 4 are provided on each side wall, located in the lower part of the side wall, and are respectively located on both sides directly below the overflow trough 5 of the side wall; the retaining wall upper holes 3 and the retaining wall lower holes 4 on each side wall are preferably respectively corresponding one by one up and down. The lower hole 4 of the retaining wall and the upper hole 3 of the retaining wall are both inclined with the inner side lower and the outer side higher, that is, they are inclined outward and upward through the side wall. The angle between the lower hole 4 of the retaining wall and the horizontal plane is 15-25°, that is, the upward angle α to the outside is 15-25°, and the angle between the upper hole 3 of the retaining wall and the horizontal plane is 15-25°, that is, the upward angle α to the outside is 15-25°. A lifting ring 2 is provided at the upper part of the middle wall. The lower part of the retaining wall is placed on the permanent layer, and the upper part is supported by two supporting bricks.

[0030] The dimensions of the retaining wall are preferably: the height of the wall body is 1000-1300mm, the thickness is 1000-1300mm; the diameter of the upper hole 3 of the retaining wall is D1=100-130mm, the height is H1=350-450mm, and the upward angle is α=15-25°; the diameter of the lower hole 4 of the retaining wall is D2=90-110mm, the height is H2=200-300mm, and the upward angle is α=15-25°.

[0031] 7. Drainage sand is added to the middle bag before baking. Use paper balls to fill the zirconium tube, and then add a small amount of drainage sand (0.5-1.5kg) to the "bowl mouth" formed by the upper part of the water inlet and the dry material at the bottom of the bag. Fill the "bowl mouth" and make it level with the dry material at the bottom of the bag to increase the baking temperature of the zirconium core at the water inlet. Pull down the paper ball when pouring to make it flow smoothly.

[0032] 8. The tundish baking is carried out in stages: starting from the heating time, the temperature is raised to 300°C within 30 minutes, then to 800-1100°C in the first 30 minutes to 4 hours, and then to 1150-1350°C. The total baking time of the tundish is 5.5-6 hours. The pouring temperature of the tundish is >1200°C. Example 1

[0033] A steel plant has 6 continuous casting machines and 6 streams, a "T" type structure, and a quick-change tundish with a capacity of 45t. The tundish smelts HRB400E steel, the liquidus temperature is 1505℃, the average tundish temperature is controlled at 1515-1530℃, the total tundish baking time is 5.5 hours, the baking temperature is 1250℃, the stable pulling speed is controlled at 4.7m / min, and the cross-section is 165mm×165mm. Low-carbon tundish covering agent with a basicity of 1.42 is used throughout the process. The first furnace of low-carbon covering agent is 210kg, 70kg on both sides of the tundish tail, and 70kg in the tundish impact zone; 40kg on both sides of the tundish tail of the second furnace, and 40kg in the tundish impact zone; 20kg on both sides of the tundish tail of the third furnace, and 20kg in the tundish impact zone. The end point C is 0.09%, and 25kg of Si-A1 deoxidizer is added to each furnace. The amount of tundish drainage sand added is 1.5kg. A slag retaining wall is used, the height of the wall body is 1000mm, the thickness is 100mm, the upper hole diameter D1=100mm, the height H1=350mm, the upward angle α=15; the lower hole diameter D2=90mm, the height H2=200mm, the upward angle α=15°. The liquid level is controlled at 900mm during the entire pouring process, and the thickness of the slag layer in the tundish is 80mm. The life of the lower line nozzle is 55h. The use results of this embodiment are shown in Table 1. Example 2

[0034] A steel plant has 7 continuous casting machines and 7 streams, a "T" type structure, and a quick-change tundish with a capacity of 60t. The tundish smelts HRB500E steel, the liquidus temperature is 1505℃, the average tundish temperature is controlled at 1520-1530℃, the total tundish baking time is 5.7 hours, the baking temperature is 1280℃, the stable pulling speed is controlled at 4.6m / min, and the cross-section is 165mm×165mm. Low-carbon tundish covering agent with a basicity of 1.30 is used throughout the process. The first furnace of low-carbon covering agent is 240kg, 80kg on both sides of the tundish tail, and 80kg in the tundish impact zone; the second furnace tundish tail is 45kg on both sides of the tundish tail, and 45kg in the tundish impact zone; the third furnace tundish tail is 30kg on both sides of the tundish tail, and 30kg in the tundish impact zone. The end point C is 0.08%, and 25kg of Si-A1 deoxidizer is added to each furnace. The amount of tundish drainage sand added is 1.3kg. A slag retaining wall is used, the height of the wall body is 1300mm, the thickness is 130mm, the upper hole diameter D1=130mm, the height H1=450mm, the upward angle α=15; the lower hole diameter D2=110mm, the height H2=300mm, the upward angle α=25°. The liquid level is controlled at 1000mm during the entire pouring process, and the thickness of the slag layer in the tundish is 80mm. The life of the lower line nozzle is 60h. The use results of this embodiment are shown in Table 1. Example 3

[0035] A steel plant has 6 continuous casting machines and 6 streams, a "T" type structure, and a quick-change tundish with a capacity of 48t. The tundish smelts HRB400E steel, the liquidus temperature is 1505℃, the average tundish temperature is controlled at 1515-1530℃, the total tundish baking time is 5.8 hours, the baking temperature is 1230℃, the stable pulling speed is controlled at 4.8m / min, and the cross-section is 150mm×150mm. Low-carbon tundish covering agent with a basicity of 1.36 is used throughout the process. The first furnace of low-carbon covering agent is 225kg, 75kg on both sides of the tundish tail, and 75kg in the tundish impact zone; the second furnace tundish tail is 55kg on both sides of the tundish tail, and 55kg in the tundish impact zone; the third furnace tundish tail is 25kg on both sides of the tundish tail, and 25kg in the tundish impact zone. The end point C is 0.10%, and 25kg of Si-A1 deoxidizer is added to each furnace. The amount of tundish drainage sand added is 0.9kg. A slag retaining wall is used, the height of the wall body is 1250mm, the thickness is 125mm, the upper hole diameter D1=135mm, the height H1=370mm, the upper elevation angle α=17; the lower hole diameter D2=105mm, the height H2=270mm, the upper elevation angle α=17°. The liquid level is controlled at 900mm during the entire pouring process, and the thickness of the slag layer in the tundish is 75mm. The life of the lower line nozzle is 60h. The use results of this embodiment are shown in Table 1. Example 4

[0036] A steel plant has 8 continuous casting machines and 8 streams, a "T" type structure, and a quick-change tundish with a capacity of 75t. The tundish smelts HRB400E steel, the liquidus temperature is 1505℃, the average tundish temperature is controlled at 1515-1520℃, the total tundish baking time is 6 hours, the baking temperature is 1300℃, the stable pulling speed is controlled at 4.5m / min, and the cross-section is 165mm×165mm. Low-carbon tundish covering agent with a basicity of 1.50 is used throughout the process. The first furnace of low-carbon covering agent is 270kg, 90kg on both sides of the tundish tail, and 90kg in the tundish impact zone; the second furnace tundish tail is 60kg on both sides of the tundish tail, and 60kg in the tundish impact zone; the third furnace tundish tail is 40kg on both sides of the tundish tail, and 40kg in the tundish impact zone. The end point C is 0.06%, and 50kg of Si-A1 deoxidizer is added to each furnace. The amount of tundish drainage sand added is 1.0kg. A slag retaining wall is used, the height of the wall body is 1200mm, the thickness is 1200mm, the upper hole diameter D1=110mm, the height H1=405mm, the upper elevation angle α=20; the lower hole diameter D2=100mm, the height H2=250mm, the upper elevation angle α=20°. The liquid level is controlled at 1100mm during the entire pouring process, and the thickness of the slag layer of the tundish is 70mm. The life of the lower line nozzle is 70h. The use results of this embodiment are shown in Table 1. Example 5

[0037] A steel plant has 7 continuous casting machines and 7 streams, a "T" type structure, and a quick-change tundish with a capacity of 63t. The tundish smelts HRB630E steel, the liquidus temperature is 1500℃, the average tundish temperature is controlled at 1510-1525℃, the total tundish baking time is 5.3 hours, the baking temperature is 1350℃, the stable pulling speed is controlled at 4.5m / min, and the cross-section is 165mm×165mm. Low-carbon tundish covering agent with a basicity of 1.39 is used throughout the process. The first furnace of low-carbon covering agent is 270kg, 90kg on both sides of the tundish tail, and 90kg in the tundish impact zone; the second furnace tundish tail is 60kg on both sides of the tundish tail, and 60kg in the tundish impact zone; the third furnace tundish tail is 40kg on both sides of the tundish tail, and 40kg in the tundish impact zone. The end point C is 0.03%, and 75kg of Si-A1 deoxidizer is added to each furnace. The amount of tundish drainage sand added is 0.5kg. A slag retaining wall is used, the height of the wall body is 1200mm, the thickness is 1200mm, the upper hole diameter D1=110mm, the height H1=405mm, the upper elevation angle α=20; the lower hole diameter D2=100mm, the height H2=250mm, the upper elevation angle α=20°. The liquid level is controlled at 1100mm during the entire pouring process, and the thickness of the slag layer of the tundish is 60mm. The life of the lower line nozzle is 65h. The use results of this embodiment are shown in Table 1.

[0038] The implementation results of Examples 1-4 are shown in Table 1; Table 1: Implementation results of various embodiments and comparative examples

[0039] In Table 1, the comparative example is an implementation case using a conventional method; the diameter expansion is the actual diameter of the downstream steel column minus the original diameter of the upstream water inlet.

Claims

1. A method for producing hot-rolled ribbed steel bars by high-speed continuous casting, characterized in that: Including converter smelting and continuous casting steps; The converter smelting step: using Si-A1 deoxidizer to control the average active oxygen content of molten steel to 35ppm or less; The continuous casting steps include: using a low-carbon tundish covering agent throughout the entire process, using 210-270kg of low-carbon covering agent for the first casting, 70-90kg on each side of the tundish tail and 70-90kg in the tundish impact zone; using 40-60kg on each side of the tundish tail and 40-60kg in the tundish impact zone for the second casting; using 20-40kg on each side of the tundish tail and 20-40kg in the tundish impact zone for the third casting; adding 3-5kg on each side of the tundish tail and in the tundish impact zone for each subsequent casting; controlling the liquid level to 900mm-1100mm throughout the casting process, and having a tundish slag layer thickness of ≤80mm; adopting a porous U-shaped retaining wall design in the tundish impact zone; and adding drainage sand to the tundish by adding sand before baking.

2. The high-speed continuous casting production method for hot-rolled ribbed steel bars according to claim 1, characterized in that: The continuous casting step: the tundish pouring temperature is greater than 1200°C.

3. The high-speed continuous casting production method for hot-rolled ribbed steel bars according to claim 1, characterized in that: In the continuous casting step, the tundish baking is performed in stages: based on the start of heating time, the temperature is raised to 300°C within 30 minutes, then raised to 800-1100°C in the first 30 minutes to 4 hours, and then raised to 1150-1350°C; the total time for tundish baking is 5.5-6 hours.

4. The high-speed continuous casting production method for hot-rolled ribbed steel bars according to claim 1, characterized in that: The continuous casting step: the continuous casting speed is controlled at 4.5 m / min to 5 m / min, and the tundish temperature is controlled at a target of liquidus temperature + (10 to 25)°C.

5. The high-speed continuous casting production method for hot-rolled ribbed steel bars according to claim 1, characterized in that: The continuous casting step: using a low-carbon tundish covering agent with a basicity of 1.30-1.50 and a viscosity of 0.145-0.150 Pa·1300°C.

6. A high-speed continuous casting production method for hot-rolled ribbed steel bars according to any one of claims 1 to 5, characterized in that: The porous U-shaped retaining wall structure comprises a retaining wall body (1), retaining wall upper holes (3), retaining wall lower holes (4) and an overflow trough (5); the retaining wall body (1) has a U-shaped structure in horizontal cross-section, and is composed of a middle wall and two side walls; the tops of the two side walls are both provided with an overflow trough (5); the retaining wall upper holes (3) and retaining wall lower holes (4) penetrating the wall body are both provided on the two side walls.

7. A method for producing hot-rolled ribbed steel bars by high-speed continuous casting according to claim 6, characterized in that: The retaining wall lower hole (4) is located at the lower part of the side wall, and the retaining wall upper hole (3) is located at the middle and lower part of the side wall.

8. The high-speed continuous casting production method for hot-rolled ribbed steel bars according to claim 6, characterized in that: The lower holes (4) of the retaining wall are arranged in a row of two, and the upper holes (3) of the retaining wall are arranged in a row of two.

9. The high-speed continuous casting production method for hot-rolled ribbed steel bars according to claim 6, characterized in that: The lower hole (4) of the retaining wall and the upper hole (3) of the retaining wall are both arranged to be inclined with the inner side lower and the outer side higher.

10. A method for producing hot-rolled ribbed steel bars by high-speed continuous casting according to claim 9, characterized in that: The angle between the lower hole (4) of the retaining wall and the horizontal plane is 15 to 25°, and the angle between the upper hole (3) of the retaining wall and the horizontal plane is 15 to 25°.

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