Method for producing foamed steel
By blowing hydrogen or hydrogen argon nitrogen mixture in the continuous casting process of liquid steel to generate tiny bubbles, the problems of uneven bubbles and high cost in foam steel production are solved, and high-quality and low-cost mass production is achieved.
Patent Information
- Application Number
- CN202510572903.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-06
- Publication Date
- 2025-07-18
AI Technical Summary
The prior art is difficult to produce foam steel with small bubble size, uniform bubble distribution and high porosity, and has high production costs and low quality stability, making it difficult to achieve large-scale production.
During the continuous casting of the steel liquid, a large amount of hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas is blown into the steel liquid by blowing a large amount of hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas at the argon seal of the immersed water port slide plate, the plug rod and the water port on the slide plate, thereby generating a large number of diffuse micro bubbles, and quickly solidifying in the crystallizer to form foam steel containing a large number of micro bubbles inside.
The production of foam steel with small bubble size, high porosity and uniform pore distribution is achieved. The production technology is simple and easy to use and the cost is low.
Smart Images
Figure CN120325916A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of steel materials, and particularly to a method for producing foamed steel. Background Art
[0002] Steel has the advantages of high strength, high plasticity, high weldability, etc., but its density is relatively large. With the development of low-carbon economy and technology, the lightweight of steel has attracted people's attention. Lightweight steel can reduce the density of steel, and for the same volume of steel, the energy consumption and material consumption in its preparation process are relatively low; and lightweight steel is convenient for transportation, and the equipment prepared with lightweight steel can save operating energy consumption during operation. In short, lightweight steel has unique advantages and can become a new type of metal material.
[0003] The prior art discloses a device for producing porous metal, including a molten metal tank, a foaming chamber, fluid holes, a partition wall, a relief valve, and a metal crystallizer. A high-frequency ultrasonic vibrator is installed in the middle of the metal crystallizer; when the high-frequency ultrasonic vibrator is started, when the molten metal containing bubbles passes through the metal crystallizer, under the action of high-frequency ultrasonic vibration, the bubbles are fragmented by ultrasonic vibration. However, due to the limited propagation distance of ultrasonic waves in molten metal, it is difficult to generate uniform and tiny bubbles in the metal. The prior art discloses a method of introducing hydrogen into a magnesium alloy, and hydrogen is dissolved in the molten magnesium alloy liquid to produce a foamed magnesium alloy profile. When the liquid solidifies, the solubility of hydrogen in the solid magnesium alloy is low, and the supersaturated hydrogen precipitates in the form of bubbles, forming a large number of bubbles in the magnesium alloy; however, this method cannot be applied to molten steel, and forming supersaturated hydrogen in molten steel requires blowing a huge amount of hydrogen into the molten steel, and this method is not feasible in the production of foamed steel. The prior art discloses a method of blowing CO2 into molten steel after melting, and CO2 reacts with carbon in the steel to generate CO; the CO gas remains in the steel in the form of bubbles, and then foamed steel with uniform bubble distribution is obtained through rapid cooling; however, the CO bubbles generated by the reaction of CO2 and carbon in the steel are large-sized bubbles, and the bubbles quickly float up and are removed, and it is very difficult to produce foamed steel by this method.
[0004] All in all, although the prior art records some technologies for producing foamed metal, the liquidus temperature of steel is relatively high, and the technologies for producing foamed copper, magnesium alloy, etc. are difficult to be directly applied to the production of foamed steel. The technology for producing foamed steel is very scarce, and some technologies that have been developed still have problems such as low quality stability, high preparation cost, and difficulty in mass production; in particular, there is a lack of a method for producing foamed steel with tiny bubble size, uniform bubble distribution, and high porosity in the steel. Summary of the Invention
[0005] To solve the problems existing in this technology, the main object of the present invention is to propose a method for producing foamed steel.
[0006] According to one aspect of the present invention, the present invention provides the following technical solutions:
[0007] A method for producing foamed steel, in which when continuous casting of molten steel is carried out, a large flow of hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas is blown into the molten steel at the argon seal of the submerged entry nozzle slide plate, the stopper rod and the nozzle on the slide plate, a large number of hydrogen-containing dispersed micro-bubbles are generated in the molten steel in the mold, and the molten steel containing a large number of hydrogen-containing dispersed micro-bubbles rapidly solidifies to form foamed steel with a large number of micro-bubbles inside.
[0008] As a preferred embodiment of the method for producing foamed steel according to the present invention, wherein: the volume proportion of hydrogen in the hydrogen-argon mixed gas and the hydrogen-nitrogen mixed gas is 50-100%.
[0009] As a preferred embodiment of the method for producing foamed steel according to the present invention, wherein: the blowing pressure of hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas is 0.4-1.5 MPa.
[0010] As a preferred embodiment of the method for producing foamed steel according to the present invention, wherein: the total flow rate Q of hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas blown into the molten steel in the nozzle at the argon seal of the submerged entry nozzle slide plate, the stopper rod and the nozzle on the slide plate is:
[0011] Q = a·v·S
[0012] wherein, Q is the total gas flow rate, NL / min; v is the casting speed, m / min; S is the cross-sectional area of the mold, m 2 ; a is a constant, 200-3000.
[0013] As a preferred embodiment of the method for producing foamed steel according to the present invention, wherein: the gas guiding structure of the nozzle on the slide plate is improved, a gas chamber of the nozzle on the slide plate is arranged inside the nozzle on the slide plate, gas guiding holes are opened from the gas chamber of the nozzle on the slide plate to the inner wall of the nozzle on the slide plate, the inner diameter of the gas guiding holes is 0.5-3 mm, the gas guiding holes guide the gas blown into from the nozzle on the slide plate to the molten steel flowing rapidly through the nozzle, and the number of the gas guiding holes is 2-20.
[0014] As a preferred embodiment of the method for producing foamed steel according to the present invention, wherein: during continuous casting, the mold and the secondary cooling zone are cooled by strong cooling, the average heat flux density of the mold is greater than 1500 kW / m 2 ; the cooling intensity of the secondary cooling zone is greater than 1.4 L / kg of steel.
[0015] As a preferred embodiment of the method for producing foamed steel according to the present invention, wherein: during continuous casting, low superheat continuous casting is adopted, and the superheat of the molten steel in the tundish is 5-25°C.
[0016] As a preferred embodiment of the method for producing foamed steel according to the present invention, during continuous casting, high-speed continuous casting is adopted, and the casting speed is greater than 2.0 m / min.
[0017] As a preferred embodiment of the method for producing foamed steel according to the present invention, the higher the hydrogen content in the blown gas, the smaller the bubble size in the produced casting blank; when the volume ratio of hydrogen in the blown gas is 50%, the average bubble size in the casting blank is less than 300 μm, the porosity of the casting blank can be greater than 20%, the bubble distribution in the casting blank is uniform, and the density deviation between the center and the edge of the casting blank is less than 50%.
[0018] As a preferred embodiment of the method for producing foamed steel according to the present invention, the blowing gas flow rate of the stopper rod or the blowing gas flow rate of the nozzle on the slide plate is higher than the blowing gas flow rate at the argon seal of the slide plate.
[0019] The beneficial effects of the present invention are as follows:
[0020] The present invention provides a method for producing foamed steel. By using the existing mature continuous casting production process equipment of the iron and steel industry, during continuous casting production, a large flow of hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas is blown into the molten steel at the argon seal of the submerged nozzle slide plate, the stopper rod and the nozzle on the slide plate, generating a large number of dispersed tiny hydrogen-containing bubbles in the molten steel in the mold. The molten steel containing a large number of dispersed tiny hydrogen-containing bubbles rapidly solidifies to form foamed steel with a large number of tiny bubbles inside. The present invention can control the porosity and bubble size in the steel by adjusting the blowing gas flow rate and composition, etc., and produce foamed steel with small bubble size, high porosity and uniform pore distribution. The production technology is simple and easy to implement, and the production cost is low. Description of the Drawings
[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.
[0022] Figure 1 Schematic diagram of the device for implementing the method for producing foamed steel of the present invention.
[0023] In the figure, 1 - stopper rod blowing; 2 - nozzle on the slide plate blowing; 3 - argon seal of the slide plate blowing; 4 - air chamber of the nozzle on the slide plate; 5 - air guide hole.
[0024] The realization, functional characteristics and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Detailed Embodiments
[0025] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.
[0026] According to one aspect of the present invention, the present invention provides the following technical solutions:
[0027] As Figure 1 shown, a method for producing foam steel, blowing gas 3 at the argon seal of the submerged entry nozzle slide plate, blowing gas 1 at the stopper rod, and blowing gas 2 at the nozzle on the slide plate during continuous casting. Specifically, during continuous casting, blowing a large flow of hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas into the molten steel at the argon seal of the submerged entry nozzle slide plate, the stopper rod, and the nozzle on the slide plate. The gas flows downward together through the submerged entry nozzle into the mold; since the molten steel flows vertically downward from above, the potential energy of the molten steel is converted into kinetic energy and turbulent kinetic energy, and the turbulent flow of the molten steel breaks the blown gas into tiny bubbles, generating a large number of dispersed tiny bubbles in the molten steel in the mold; further, part of the hydrogen and nitrogen in the bubbles dissolve into the molten steel, and the bubble size becomes even smaller; these tiny bubbles flow with the molten steel and are evenly distributed in the molten steel in the mold. Due to their very small size, it is difficult for them to float upward; the molten steel containing a large number of dispersed tiny hydrogen-containing bubbles solidifies rapidly, forming a slab with a large number of tiny bubbles inside.
[0028] Preferably, the volume ratio of hydrogen in the hydrogen-argon mixed gas and the hydrogen-nitrogen mixed gas is 50-100%. Specifically, the volume ratio of hydrogen in the hydrogen-argon mixed gas and the hydrogen-nitrogen mixed gas can be, for example, any one or the range between any two of 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%.
[0029] Preferably, the blowing pressure of hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas is 0.4-1.5 MPa. Specifically, the blowing pressure of hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas can be, for example, any one or the range between any two of 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa.
[0030] Preferably, the total flow rate Q of blowing hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas into the molten steel in the nozzle at the argon seal of the submerged entry nozzle slide plate, the stopper rod, and the nozzle on the slide plate is:
[0031] Q = a·v·S
[0032] Among them, Q is the total gas flow rate, NL / min; v is the drawing speed, m / min; S is the cross-sectional area of the mold, m 2 ; a is a constant, 200 - 3000.
[0033] Preferably, as Figure 1 shown, the gas guiding structure of the nozzle on the slide plate is improved. There is a gas chamber 4 of the nozzle on the slide plate inside the nozzle on the slide plate. Gas guiding holes 5 are led from the gas chamber 4 of the nozzle on the slide plate to the inner wall of the nozzle on the slide plate. The inner diameter of the gas guiding holes 5 is 0.5 - 3 mm. The gas guiding holes 5 guide the gas blown into the nozzle on the slide plate to the molten steel that rapidly pours through the nozzle. The number of the gas guiding holes 5 is 2 - 20.
[0034] Preferably, during continuous casting, the mold and the secondary cooling zone are cooled with strong cooling. The average heat flux density of the mold is greater than 1500 kW / m 2 ; the cooling intensity of the secondary cooling zone is greater than 1.4 L / kg of steel. Preferably, low superheat continuous casting is adopted during continuous casting, and the superheat of the molten steel in the tundish is 5 - 25 °C. Specifically, the superheat of the molten steel in the tundish can be any one of, for example, 5 °C, 10 °C, 15 °C, 20 °C, 25 °C or the range between any two of them. Preferably, high-speed continuous casting is adopted during continuous casting, and the drawing speed of the slab is greater than 2.0 m / min. Adopting the said process conditions is beneficial to the rapid solidification of the slab, reducing the time and opportunity for bubble aggregation and growth, so that the bubbles existing in the molten steel can be retained in the slab more and more evenly.
[0035] Preferably, the higher the hydrogen content in the blown gas, the smaller the bubble size in the produced slab. Specifically:
[0036] When the volume fraction of hydrogen in the blown gas is 50%, the average size of the bubbles in the slab is less than 300 μm, the porosity of the slab can be greater than 20%, the bubbles in the slab are evenly distributed, and the density deviation between the center and the edge of the slab is less than 50%;
[0037] When the volume fraction of hydrogen in the blown gas is 70%, the average size of the bubbles in the slab is less than 150 μm, the porosity of the slab can be greater than 40%, the distribution of the bubbles in the slab is more uniform than when the volume fraction of hydrogen is 50%, and the density difference between the center and the edge of the slab is less than 30%;
[0038] When the volume fraction of hydrogen in the blown gas is 80%, the average size of the bubbles in the slab is less than 120 μm, the porosity of the slab can be greater than 45%, the distribution of the bubbles in the slab is more uniform than when the volume fraction of hydrogen is 70%, and the density difference between the center and the edge of the slab is less than 20%;
[0039] After the volume fraction of hydrogen in the blown-in gas is greater than 90%, the average size of the bubbles in the continuous casting billet is less than 100 μm, the porosity of the continuous casting billet can be greater than 50%, the bubble distribution in the continuous casting billet is more uniform than when the volume fraction of hydrogen is 80%, and the density difference between the center and the edge of the continuous casting billet is less than 10%.
[0040] Preferably, the blowing gas flow rate of the stopper rod or the blowing gas flow rate of the nozzle on the slide plate is higher than the blowing gas flow rate at the argon seal of the slide plate.
[0041] The technical solution of the present invention will be further described below in conjunction with specific embodiments.
[0042] Example 1
[0043] A certain domestic steel mill uses thin slab continuous casting and rolling to produce thin slabs. The cross-sectional area of the mold of the continuous caster is 0.13 m 2 , and the casting speed is 5 m / min. When continuous casting, a hydrogen-argon mixed gas is blown through the stopper rod, and the flow rate of the hydrogen-argon mixed gas is 300 L / min; a hydrogen-argon mixed gas is blown through the nozzle on the slide plate, and the flow rate of the hydrogen-argon mixed gas is 1500 L / min; a hydrogen-argon mixed gas is blown at the argon seal of the slide plate, and the flow rate of the hydrogen-argon mixed gas is 60 L / min. The pressure of the hydrogen-argon mixed gas is 0.5 MPa, and the volume fraction of hydrogen in the hydrogen-argon mixed gas is 90%; the mold is strongly cooled, and the average heat flux density is 2000 kW / m 2 , and the secondary cooling is carried out in a strong cooling mode, and the specific water consumption of the secondary cooling is 1.5 L / kg of steel. A foamed continuous casting billet is produced by continuous casting. The porosity in the continuous casting billet reaches 61%, the average internal bubble is 50 μm, the bubbles are evenly distributed in the steel, and the density difference between the center and the edge of the continuous casting billet is less than 10%.
[0044] Example 2
[0045] A certain domestic steel mill uses thin slab continuous casting and rolling to produce thin slabs. The cross-sectional area of the mold of the continuous caster is 0.12 m 2 , and the casting speed is 6 m / min. When continuous casting, a hydrogen-nitrogen mixed gas is blown through the stopper rod, and the flow rate of the hydrogen-nitrogen mixed gas is 300 L / min. A hydrogen-nitrogen mixed gas is blown through the nozzle on the slide plate, and the flow rate of the hydrogen-nitrogen mixed gas is 1800 L / min. A hydrogen-nitrogen mixed gas is blown at the argon seal of the slide plate, and the flow rate of the hydrogen-nitrogen mixed gas is 30 L / min. The pressure of the hydrogen-nitrogen mixed gas is 0.8 MPa, and the volume fraction of hydrogen in the hydrogen-nitrogen mixed gas is 90%; the mold is strongly cooled, and the average heat flux density is 2500 kW / m 2 , and the secondary cooling is carried out in a strong cooling mode, and the specific water consumption of the secondary cooling is 1.7 L / kg of steel. A foamed continuous casting billet is produced by continuous casting. The porosity in the continuous casting billet reaches 72%, the average internal bubble is 42 μm, and the density difference between the center and the edge of the continuous casting billet is less than 10%.
[0046] Example 3
[0047] A certain domestic steel plant uses a small billet continuous caster to produce foam billets. The cross-sectional area of the crystallizer of the continuous caster is 0.0256 m 2 , and the casting speed is 6 m / min. During continuous casting, hydrogen is blown through the stopper with a flow rate of 50 L / min, hydrogen is blown through the nozzle on the slide plate with a flow rate of 400 L / min, and hydrogen is blown at the argon seal of the slide plate with a flow rate of 10 L / min. The hydrogen pressure is 0.5 MPa; the crystallizer is strongly cooled with an average heat flux density of 1500 kW / m 2 , and the secondary cooling adopts a strong cooling method with a secondary cooling water ratio of 1.9 L / kg steel. The continuous casting produces foam cast billets with a porosity of 65% in the cast billets, an average internal bubble of 68 μm, and a density difference between the center and the edge of the cast billet less than 10%.
[0048] The present invention utilizes the existing mature continuous casting production process equipment in the iron and steel industry. During continuous casting, a large flow of hydrogen, hydrogen-argon mixed gas or hydrogen-nitrogen mixed gas is blown into the molten steel at the argon seal of the submerged nozzle slide plate, the stopper and the nozzle on the slide plate, and a large number of dispersed tiny hydrogen-containing bubbles are generated in the molten steel in the crystallizer. The molten steel containing a large number of dispersed tiny hydrogen-containing bubbles rapidly solidifies to form foam steel with a large number of tiny bubbles inside. By regulating the gas flow rate and composition blown in, the porosity and bubble size in the steel are controlled to produce foam steel with small bubble size, high porosity and uniform pore distribution. The production technology is simple and easy to implement, and the production cost is low.
[0049] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made using the content of the specification of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.
Claims
1. A method for producing foam steel, characterized in that, During continuous casting production, hydrogen, a hydrogen-argon mixture gas, or a hydrogen-nitrogen mixture gas is blown into the molten steel in the tundish through the argon seal of the submerged entry nozzle slide plate, the stopper rod, and the nozzle on the slide plate. The gas flows downward together with the molten steel through the submerged entry nozzle and into the mold. A large number of dispersed and tiny hydrogen-containing bubbles are generated in the molten steel in the mold. These tiny hydrogen-containing bubbles flow with the molten steel and are evenly distributed in the molten steel in the mold. The molten steel containing a large number of dispersed and tiny hydrogen-containing bubbles solidifies rapidly to form a slab with a large number of tiny bubbles inside.
2. The method for producing foamed steel according to claim 1, characterized in that, The volume ratio of hydrogen in the hydrogen-argon mixture gas and the hydrogen-nitrogen mixture gas is 50-100%.
3. The method for producing foamed steel according to claim 1, characterized in that, The blowing pressure of hydrogen, the hydrogen-argon mixture gas, or the hydrogen-nitrogen mixture gas is 0.4-1.5 MPa.
4. The method for producing foamed steel according to claim 1, characterized in that, The total flow rate Q of blowing hydrogen, the hydrogen-argon mixture gas, or the hydrogen-nitrogen mixture gas into the molten steel in the tundish through the argon seal of the submerged entry nozzle slide plate, the stopper rod, and the nozzle on the slide plate is: Q = a·v·S Among them, Q is the total gas flow rate, NL / min; v is the drawing speed, m / min; S is the cross-sectional area of the mold, m 2 ; a is a constant, 200 - 3000.
5. The method for producing foamed steel according to claim 1, characterized in that, A tundish nozzle gas chamber is arranged inside the nozzle on the slide plate. Gas guiding holes are led from the tundish nozzle gas chamber to the inner wall of the nozzle on the slide plate. The gas guiding holes guide the gas blown from the nozzle on the slide plate to the molten steel flowing rapidly downward through the nozzle. The inner diameter of the gas guiding holes is 0.5-3 mm, and the number of the gas guiding holes is 2-20.
6. The method for producing foamed steel according to claim 1, characterized in that, During continuous casting, the mold and the secondary cooling zone are cooled with strong cooling, and the average heat flux density of the mold is greater than 1500 kW / m 2 ; the cooling intensity of the secondary cooling zone is greater than 1.4 L / kg of steel.
7. The method for producing foamed steel according to claim 1, characterized in that, During continuous casting, low superheat continuous casting is adopted, and the superheat of the molten steel in the tundish is 5-25 °C.
8. The method for producing foamed steel according to claim 1, characterized in that, During continuous casting, high-speed continuous casting is adopted, and the casting speed of the slab is greater than 2.0 m / min.
9. The method for producing foamed steel according to claim 1, characterized in that, The higher the hydrogen content in the blown gas, the smaller the bubble size in the produced slab. When the volume ratio of hydrogen in the blown gas is 50%, the average bubble size in the slab is less than 300 μm, the porosity of the slab is greater than 20%, the bubbles in the slab are evenly distributed, and the density deviation between the center and the edge of the slab is less than 50%.
10. The method for producing foamed steel according to claim 1, characterized in that, The blowing flow rate of the stopper rod or the blowing flow rate of the nozzle on the slide plate is higher than the blowing flow rate at the argon seal of the slide plate.