A method of adjusting the composition field of a continuous hot dip galvanizing zinc pot

Abstract

The present application relates to the technical field of metal material processing, and discloses a method for adjusting the composition field of a continuous hot-dip galvanizing zinc pot, comprising the following steps: S1, pre-preparing F ingots (high-aluminum zinc ingots) for adjusting local composition; S2, detecting the aluminum content in the zinc pot; S3, analyzing the effective aluminum content in the zinc pot; S4, supplementing A ingots (pure zinc ingots) and B ingots (Zn-0.2%Al) according to the distribution of the effective aluminum in the zinc pot; S5, supplementing F ingots (high-aluminum zinc ingots) according to the distribution of the effective aluminum in the zinc pot, and adjusting the local composition of the zinc pot; S6, simulating the multi-field coupling of the zinc pot, and optimizing the adding position and frequency of the F ingots (high-aluminum zinc ingots); and S7, adjusting the adding frequency of the A ingots (pure zinc ingots), the B ingots (Zn-0.2%Al) and the F ingots (high-aluminum zinc ingots) according to the production plan. The method combines the multi-field coupling simulation of the composition field, the temperature field and the flow field in the zinc pot, adjusts the composition and supplementing position of the zinc-aluminum ingots, optimizes the composition of the zinc pot, makes the effective aluminum content in the V-shaped area of the zinc pot low, and makes the effective aluminum content around the zinc pot high.

Description

Technical Field

[0001] This invention relates to the field of metal material processing technology, and more specifically discloses a method for adjusting the composition field of a zinc bath in continuous hot-dip galvanizing. Background Technology

[0002] With the rapid development of the automotive industry in recent years towards energy conservation, lightweighting, and environmental protection, the application of high-strength steel in automobiles has been increasing year by year, and GA steel sheet is a commonly used automotive outer panel. To avoid the continuous accumulation of bottom dross during the production of GA products, reduce the frequency of manual dross removal, and control the composition of the continuous galvanizing bath, especially the effective aluminum content, is crucial. Effective aluminum refers to aluminum dissolved in the zinc bath, and its content is generally in the range of 0.13-0.14%. Depending on the effective aluminum content, the formed zinc dross may be Fe2Al5Znx(η), FeZn10(δ), or a combination thereof, specifically related to the effective aluminum content at the δ-η phase transformation point. Therefore, optimizing the composition of the zinc bath, especially controlling the effective aluminum content, is critical.

[0003] During continuous hot-dip galvanizing, the steel and zinc dross in the zinc pot continuously consume zinc and aluminum. Therefore, in production practice, zinc ingots, zinc-aluminum alloy ingots, and zinc-aluminum alloy ingots with high aluminum content are added to replenish the zinc and aluminum consumed by the steel and zinc dross. However, the melting of zinc ingots, the ratio of zinc-aluminum alloy ingots, and the location of zinc and aluminum replenishment all significantly affect the heat and mass balance within the zinc pot, altering the flow pattern of the molten zinc. This flow pattern, in turn, influences the distribution of other components within the zinc pot. Studying the distribution of these components and optimizing the distribution of effective aluminum in the zinc pot plays a crucial role in obtaining a high-quality galvanized layer and reducing zinc dross formation. Summary of the Invention

[0004] The main technical problem solved by this invention is to provide a method for adjusting the composition field of the zinc bath in continuous hot-dip galvanizing, which can solve the problem of continuous accumulation of bottom slag and high frequency of bottom slag removal operations during the production of GA products.

[0005] To solve the above-mentioned technical problems, according to one aspect of the present invention, more specifically, a method for adjusting the composition field of a zinc bath in continuous hot-dip galvanizing, comprising the following steps: S1, F-ingots (high-alumina zinc ingots) with pre-formed locally adjusted composition; S2. Detect the aluminum content inside the zinc pot; S3. Analyze the effective aluminum content in the zinc pot; S4. Replenish A ingots (pure zinc ingots) and B ingots (Zn-0.2%Al) according to the distribution of effective aluminum in the zinc pot; S5. Add F ingots (high-aluminum zinc ingots) according to the distribution of effective aluminum in the pot to adjust the local composition of the zinc pot. S6. Simulation of multi-field coupling between the junction and zinc pot to optimize the addition location and frequency of F ingot (high-alumina zinc ingot); S7. Adjust the addition frequency of A ingot (pure zinc ingot), B ingot (Zn-0.2%Al), and F ingot (high-aluminum zinc ingot) according to the production plan.

[0006] Furthermore, in S1, the Al content in the F ingot (high-aluminum zinc ingot) is 2-7 wt%.

[0007] Furthermore, in S1, the weight of the F ingot (high-aluminum zinc ingot) is 200-500 kg.

[0008] Furthermore, in S1, the shape of the F ingot (high-aluminum zinc ingot) can be, but is not limited to, square or round.

[0009] Furthermore, in S2, the method for detecting the aluminum content in the zinc pot can be, but is not limited to, chemical analysis or Galvalib online analysis.

[0010] Furthermore, in S3, the effective aluminum content in the zinc pot can be calculated using, but is not limited to, thermodynamic analysis or software calculation.

[0011] Furthermore, in step S4, when the aluminum concentration is high, ingot A (pure zinc ingot) is supplied, and when the aluminum concentration is low, ingot B (Zn-0.2%Al) is supplied.

[0012] Furthermore, in S6, the position of the F ingot (high-aluminum zinc ingot) can be, but is not limited to, the periphery of the zinc pot or the vicinity of the furnace nose. Preferably, the F ingot (high-aluminum zinc ingot) is added to the bottom opposite side of the zinc pot induction heater and the back side of the furnace nose.

[0013] The beneficial effects of the method for adjusting the composition field of a continuous hot-dip galvanizing zinc bath according to the present invention are as follows: by combining multi-field coupling simulation of the composition field, temperature field and flow field in the zinc pot, the composition and replenishment position of zinc and aluminum ingots are adjusted, and the composition of the zinc pot is optimized so that the effective aluminum content is low in the V-shaped zone of the zinc pot and high in the effective aluminum content around the zinc pot. This can make the effective aluminum content near the V-shaped zone lower than the "Kneepoint". If the effective aluminum content in other areas is higher than the "Kneepoint", the distribution of effective aluminum in the zinc pot is optimized, achieving regional slag control and improving production efficiency and product quality. Attached Figure Description

[0014] The present invention will now be described in further detail with reference to the accompanying drawings and specific implementation methods.

[0015] Figure 1 The phase diagram of the Fe-Zn-Al ternary phase diagram at 455℃ is the zinc-rich angle phase diagram; Figure 2 Schematic diagram of zinc pot and V-shaped zone; Figure 3 This is a flowchart illustrating the method. Figure 4 This is a schematic diagram showing the location of the ingot replenishment method; Figure 5 This is a schematic diagram showing the location of the second method of ingot replenishment; Figure 6 This is a schematic diagram of the three positions for ingot replenishment.

[0016] In the diagram: 1. Submerged roller; 2. Steel strip; 3. Stabilizing roller; 4. Zinc pot; 5. Furnace nose. Detailed Implementation

[0017] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0018] According to one aspect of the invention, such as Figure 1-3 As shown, a method for adjusting the composition field of the zinc bath in continuous hot-dip galvanizing is provided. The correlation coefficient of the Fe-Al-Zn system zinc-rich angle plays an important role in analyzing the action mode and distribution law of aluminum in the zinc bath. Figure 1 The diagram shows the zinc-rich angle phase of the Fe-Zn-Al ternary phase diagram at 455℃. When the effective aluminum in the zinc pot is higher than the "Kneepoint" shown in the diagram, the phase in equilibrium with the zinc liquid is Fe2Al5Znx(η). Since this phase has a lower density than the zinc liquid, it forms scum. When the effective aluminum in the zinc pot is lower than the "Kneepoint" shown in the diagram, the phase in equilibrium with the zinc liquid may be FeZn10(δ) or FeZn13(δ). These two phases have a higher density than the zinc liquid and form bottom scum. Figure 2 This is a schematic diagram of the zinc pot and the V-shaped zone. Steel strip 2 enters the molten zinc from the furnace nose 5, passes through the submerged roller 1, and exits from the stabilizing roller 3. The area traversed by steel strip 2 is the V-shaped zone. According to phase equilibrium, if the effective aluminum content near the V-shaped zone is lower than the "Knee point," bottom dross forms; if the effective aluminum content in other areas is higher than the "Knee point," scum forms. Therefore, the formation of zinc dross can be adjusted by optimizing the distribution of effective aluminum within the zinc pot. Example

[0019] Pre-fabricated high-alumina zinc ingots (F ingots) with locally adjusted composition were used. The zinc pot temperature was 455℃, and the steel plate temperature was 470℃. Based on the results of chemical analysis and effective aluminum calculations, the overall average effective aluminum content of the zinc pot was 0.14wt%. Pure zinc ingots and B ingots were added to maintain the overall average effective aluminum content of the zinc pot at around 0.1335wt%. Figure 4Eight F-ingots and two large ingots (B-ingots) were added to the indicated location. The aluminum concentration in the entire V-shaped region was initially slightly low, and under the influence of gravity, the aluminum diffused horizontally and then vertically. As the F-ingots continued to melt, the aluminum diffusion gradually spread throughout the zinc bath, reaching the bottom by 4 minutes. Outside the entire V-shaped region, the aluminum concentration gradually increased; as the V-shaped region was replenished, the aluminum concentration in the outer area gradually increased, with higher concentrations around the edges. With this F-ingot addition method, the zinc pot exhibited a trend of higher aluminum concentrations around the edges and lower aluminum concentrations in the V-shaped region.

[0020] Comparative Example 1 Pre-fabricated high-alumina zinc ingots (F ingots) with locally adjusted composition were used. The zinc pot temperature was 455℃, and the steel plate temperature was 470℃. Based on the results of chemical analysis and effective aluminum calculations, the overall average effective aluminum content of the zinc pot was 0.14wt%. Pure zinc ingots and B ingots were added to maintain the overall average effective aluminum content of the zinc pot at around 0.1335wt%. Figure 5 Eight F-ingots and two large ingots (B-ingots) were added at the indicated locations. Aluminum diffused near the horizontal plane, and after about 1 minute of diffusion, the entire horizontal plane was basically saturated. It then diffused vertically downwards along the zinc pot; however, the aluminum concentration on the back side of the inlet steel strip was not replenished. The aluminum concentration near the heater sides, however, was continuously replenished, with a higher concentration distribution than on the back side of the inlet steel strip. Aluminum continued to diffuse downwards, and near the end of melting, the aluminum concentration on the back side of the inlet steel strip remained relatively low. With this F-ingot addition method, the aluminum concentration on the back side of the steel strip was low and not replenished.

[0021] Comparative Example 2 Pre-fabricated high-alumina zinc ingots (F ingots) with locally adjusted composition were used. The zinc pot temperature was 455℃, and the steel plate temperature was 470℃. Based on the results of chemical analysis and effective aluminum calculations, the overall average effective aluminum content of the zinc pot was 0.14wt%. Pure zinc ingots and B ingots were added to maintain the overall average effective aluminum content of the zinc pot at around 0.1335wt%. Figure 6 Eight F-ingots and two large ingots (B-ingots) were added at the indicated locations. Aluminum first diffused into the V-shaped area and before the air knife, and then gradually diffused downwards. The diffusion of aluminum on the back side of the steel strip inlet was relatively low, making it difficult to form a high-aluminum area at first. However, as the aluminum ingots continued to diffuse, the back side of the steel strip was also replenished. With this F-ingot addition method, the V-shaped area was slightly higher, and the aluminum concentration was high on the back side of the steel strip inlet (behind the zinc pot).

[0022] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention are also within the protection scope of the present invention.

Claims

1. A method for adjusting the composition field of a zinc bath in a continuous hot-dip galvanizing process, characterized in that, Includes the following steps: S1. Pre-formed F ingot with locally adjusted composition, wherein F ingot is a high-aluminum zinc ingot; S2. Detect the aluminum content inside the zinc pot; S3. Analyze the effective aluminum content in the zinc pot; S4. Replenish A ingots and B ingots according to the distribution of effective aluminum in the zinc pot. Ingot A is pure zinc ingot and ingot B is Zn-0.2%Al. Replenish A ingots when the aluminum concentration is high and replenish B ingots when the aluminum concentration is low. S5. Add F ingots according to the distribution of effective aluminum in the pot to adjust the local composition of the zinc pot; S6. Optimize the addition location and frequency of F ingots by combining multi-field coupled simulation of the composition field, temperature field and flow field inside the zinc pot; S7. Adjust the addition frequency of ingot A, ingot B, and ingot F according to the production plan; This method ensures that the effective aluminum content is low in the V-shaped zone of the zinc pot and high around the perimeter, resulting in effective aluminum content near the V-shaped zone being lower than the "Knee point" and in other areas being higher than the "Knee point," thus achieving slag control by zone.

2. The method for adjusting the composition field of a continuous hot-dip galvanizing zinc bath according to claim 1, characterized in that: In S1, the Al content in the F ingot is 2-7 wt%.

3. The method for adjusting the composition field of a continuous hot-dip galvanizing zinc bath according to claim 1, characterized in that: In S1, the weight of the F ingot is 200-500 kg.

4. The method for adjusting the composition field of a continuous hot-dip galvanizing zinc bath according to claim 1, characterized in that: In S1, the shape of the F ingot is square or circular.

5. A method for adjusting the composition field of a continuous hot-dip galvanizing zinc bath according to claim 1, characterized in that: In step S2, the aluminum content in the zinc pot is detected by chemical analysis or Galvalib online analysis.

6. The method for adjusting the composition field of a continuous hot-dip galvanizing zinc bath according to claim 1, characterized in that: In S3, the effective aluminum content in the zinc pot is calculated by thermodynamic analysis or software calculation.

7. The method for adjusting the composition field of a continuous hot-dip galvanizing zinc bath according to claim 1, characterized in that: In S6, F ingots are added to the bottom opposite side and the back side of the furnace nose of the zinc pot induction heater.

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