Tinplate and its manufacturing method

Abstract

This application provides a tinplate and a manufacturing method thereof. The manufacturing method involves electroplating, soft melting, quenching with water, and passivation on the substrate in sequence to obtain the tinplate. Tin is used as the anode to form a tin layer on the surface of the substrate. The temperature of the electroplating solution is controlled at 35 - 55°C, and the Fe concentration in the electroplating solution is not higher than 10 g / L. The soft melting temperature is controlled at 240 - 290°C. The quenching with water process includes spray quenching, and the water flow rate M of the spray quenching satisfies: 0.022 × M × ΔT ≤ M ≤ 0.026 × M × ΔT, where T = -35 × H + 87, and the quenching temperature with water is T ± 3°C. Here, M is the mass of the substrate passing through any working point in the quenching with water process per unit time, ΔT is the temperature difference before and after the substrate is quenched with water, and H is the value of the substrate thickness. The tinplate obtained by the manufacturing method of this application solves the problems of many surface gaps and poor corrosion resistance after the tinplate in the prior art is processed and deformed. 2+ The concentration is not higher than 10 g / L; the soft melting temperature is controlled at 240 - 290°C; the quenching with water process includes spray quenching, and the water flow rate M of the spray quenching satisfies: 0.022 × M × ΔT ≤ M ≤ 0.026 × M × ΔT, where T = -35 × H + 87, and the quenching temperature with water is T ± 3°C. Here, M is the mass of the substrate passing through any working point in the quenching with water process per unit time, ΔT is the temperature difference before and after the substrate is quenched with water, and H is the value of the substrate thickness. The tinplate obtained by the manufacturing method of this application solves the problems of many surface gaps and poor corrosion resistance after the tinplate in the prior art is processed and deformed. 水流量 satisfies: 0.022 × M 基板 × ΔT 基板 ≤ M 水流量 ≤ 0.026 × M 基板 × ΔT 基板 , T 淬水 = -35 × H 基板 + 87, and the quenching temperature with water is T 淬水 ± 3°C; where, M 基板 is the mass of the substrate passing through any working point in the quenching with water process per unit time, ΔT 基板 is the temperature difference before and after the substrate is quenched with water, and H 基板 is the value of the substrate thickness. The tinplate obtained by the manufacturing method of this application solves the problems of many surface gaps and poor corrosion resistance after the tinplate in the prior art is processed and deformed.

Description

Technical Field

[0001] The present application relates to the technical field of alloy materials, and particularly relates to a tinplate with high corrosion resistance and a manufacturing method thereof. Background Art

[0002] Tinplate is a thin steel plate with tin plating on both sides, mainly used for manufacturing the body, top and bottom covers of beverage cans, food cans, aerosol cans, etc. With the development of production technology, the automation degree of high-end food and beverage can production lines is extremely high, and the tinplate undergoes a large amount of deformation in the key processes of can manufacturing. Especially at the multiple necking positions at the top of the can body, obvious deformation will occur in the substrate and the tin layer, and this deformation will make the original tin layer and alloy layer more loose, resulting in the exposure of the steel matrix at the microscopic level.

[0003] Such as Figure 1 shows a schematic diagram of the tin-iron alloy layer, tin layer, and passivation film of tinplate produced by the current conventional process. Its protection effect is discontinuous. Therefore, the probability of loose voids appearing at the same position in the three-layer protective layer will increase, thus exposing the iron matrix. When the tinplate is used as the packaging container for food cans, the tin layer and the tin-iron alloy layer will produce a polarization effect with the iron matrix in this medium. The more voids there are in the protective layer, the greater the probability of forming continuous voids, and the worse its corrosion resistance when used as a food can. Especially at complex deformation positions, the voids become larger and the number increases after the loose voids are deformed, affecting the use effect.

[0004] The invention patent with the patent publication number CN115558965A discloses a method for improving the surface corrosion resistance of low-tin tinplate. By annealing to control the grain orientation of the substrate, using XRD to analyze the above grain orientation, and controlling the surface characteristics through electroplating and alkali washing, the tin plating layer is deposited by the Florentine tin plating process. Finally, the strip steel is processed through conventional soft melting and conventional passivation processes. This method can reduce the incidence rate of surface rust defects of low-tin tinplate for manufacturers and users. However, this method requires frequent sampling and testing, and the XRD microscopic characterization testing requires sample preparation, grinding, testing, and analysis, and the entire cycle is relatively long, unable to meet the detection timeliness of industrial batch production. In addition, the soft melting and passivation in this invention are all conventional processes and cannot meet the corrosion resistance of the aforementioned tinplate at relatively complex deformation positions.

[0005] The invention patent with the publication number CN114381779A discloses a tinplate with an extremely low tin content and good corrosion resistance and a preparation method thereof. In this invention, the tinplate is subjected to chemical and electrochemical phosphating treatment in a phosphating solution to obtain a tinplate with a phosphating film; the tinplate with the phosphating film is passivated in a chromate passivation solution, effectively improving the corrosion resistance of the tinplate with an extremely low tin content. However, this invention requires equipment transformation, adding chemical phosphating and electrochemical phosphating plating solution tanks and drying equipment, increasing additional production costs. At the same time, in this invention, the chemical phosphating time is 30s - 1200s, the phosphating time of the electrochemical phosphating treatment is 1s - 180s, and the drying time is 10s - 300s. The upper limit of the phosphating time is extremely long, which cannot meet the requirements of high-speed electroplating tin production. In addition, the essence of the phosphating treatment is to add an additional protective layer between the tin layer and the passivation layer, and the structure of the tin layer and the alloy layer has not been significantly improved.

[0006] The invention patent with the publication number CN118703746A discloses an additive for a PSA electroplating tin insoluble anode system and a production method of tinplate. This method adopts a phenol sulfonic acid insoluble anode electroplating process system. An additive obtained by uniformly mixing a certain proportion of sodium dimercaptopropane sulfonate, sodium gluconate, sodium bicarbonate, and sodium carbonate is added to the quenching tank, so that the tin oxide film on the surface of the electroplated tinplate obtained after quenching is ≤ 1mC / cm 2 , and then the surface of the electroplated tinplate is passivated to improve the corrosion resistance and adhesion of the electroplated tinplate. However, this process mainly relies on the phenol sulfonic acid electroplating process, and the plating solution is not easy to recycle and is prone to causing pollution. In addition, this invention does not describe in detail the specific methods and detailed parameters of processes such as soft melting and quenching. Summary of the Invention

[0007] The purpose of this application is to provide a manufacturing method of tinplate. In this invention, the key processes of electroplating, soft melting, quenching, and passivation are jointly controlled. The influence of each link on various surface forming layers during production is fully considered, and the relevant parameters in each process are controlled, so that a tin-iron alloy layer with slender and continuous grains is formed on both sides of the substrate surface, and a tin layer with fine, dense, and uniform grains is formed on the tin-iron alloy layer. It solves the problems of many surface gaps and poor corrosion resistance after the tinplate is processed and deformed in the prior art, and meets the requirements of complex processing and canning.

[0008] In order to achieve one of the above-mentioned invention purposes, an embodiment of this application provides a manufacturing method of tinplate, which uses a substrate to sequentially perform electroplating, soft melting, quenching, and passivation to obtain a tinplate, wherein:

[0009] In the electroplating process, metallic tin is used as the anode to form a tin layer on the surface of the substrate, and the temperature of the electroplating solution is controlled at 35 - 55 °C, and the Fe 2+ concentration in the electroplating solution is not higher than 10 g / L;

[0010] In the fusing process, the fusing temperature is controlled at 240 - 290 °C;

[0011] In the quenching process, it includes spray quenching, and the water flow rate M of the spray quenching 水流量 satisfies: 0.022 × M 基板 × ΔT 基板 ≤ M 水流量 ≤ 0.026 × M 基板 × ΔT 基板 , the quenching target temperature = -35 × H 基板 + 87; the quenching temperature is the quenching target temperature - 3 °C to the quenching target temperature + 3 °C;

[0012] wherein, M 基板 is the mass of the substrate passing through any working point in the quenching process per unit time, ΔT 基板 is the temperature difference of the substrate before and after quenching, H 基板 is the value of the substrate thickness, with the unit of mm.

[0013] As a further improvement of an embodiment of the present application, methanesulfonic acid is used as the electroplating solution, and the free acid concentration of methanesulfonic acid is 32 - 40 ml / L, and the Sn 2+ concentration is 16 - 20 g / L.

[0014] As a further improvement of an embodiment of the present application, in the electroplating process, the forward speed of the substrate is 200 - 400 m / min.

[0015] As a further improvement of an embodiment of the present application, in the electroplating process, the total current on one side of the substrate is 4.1 - 40.4 KA, and the cathode current efficiency is 75 - 95%.

[0016] As a further improvement of an embodiment of the present application, the fusing process adopts a combined fusing method of resistance fusing and induction fusing. The alternating current frequency of the resistance fusing is 40 - 60 Hz, the induction fusing is high-frequency induction fusing, the current frequency is 200 - 350 kHz, and the fusing height is 2 - 5 m.

[0017] As a further improvement of an embodiment of the present application, when spray quenching, quenching nozzles are respectively arranged on both sides of the substrate. Taking the horizontal plane as 0°, the angles of the quenching nozzles on both sides of the substrate are -45° to 45°.

[0018] As a further improvement of an embodiment of the present application, the angles of the quenching nozzles on both sides of the substrate are -45°, -30°, -15°, 0°, 15°, 30° or 45°.

[0019] As a further improvement of an embodiment of the present application, in the quenching process, after spray quenching is completed, immersion quenching is further included, and the temperature of the quenching tank for immersion quenching is the same as the quenching temperature.

[0020] As a further improvement of an embodiment of the present application, in the passivation process, electrochemical passivation is adopted, sodium dichromate solution is used as the passivation solution, the concentration of the sodium dichromate solution is 20 - 26 g / L, the pH value of the passivation solution is 4.2 - 4.7, the temperature of the passivation solution is 40 - 50 °C, and the passivation charge density is 150 - 180 C / m 2 。

[0021] The present application also provides a tinplate, which includes a substrate and a tin - iron alloy layer, a tin layer, and a passivation film attached to the surface of the substrate in sequence. The tin content in the tinplate is 0.9 - 2.8 g / m 2 ,wherein the tin - iron alloy content is 0.4 - 0.8 g / m 2 ,the difference in tin content between any two points in the tin - plated steel sheet ≤ 0.2 g / m 2 ,and the chromium content in the passivation film is 4 - 6 mg / m 2 。

[0022] One or more technical solutions provided by the present application have at least the following technical effects or advantages:

[0023] In the manufacturing method of the tinplate provided by the present application, full - process joint control is carried out from key processes such as electroplating, soft melting, and quenching, fully considering the influence of each link on various surface - formed layers during production, so that a tin - iron alloy layer with slender and continuous grains is formed on both sides of the tinplate, and a tin layer with fine, dense, and uniform grains is formed on the tin - iron alloy layer; thus, a multi - layer dense protective layer is formed on the substrate, further improving the corrosion resistance of the tinplate at multiple necking and deformation parts, and meeting the surface performance requirements under the complex processing conditions of large deformation of the tinplate. Description of the Drawings

[0024] Figure 1 is a schematic structural diagram of the tin - iron alloy layer, tin layer, and passivation film of a tinplate produced by a conventional process.

[0025] Figure 2 is a schematic structural diagram of the tin - iron alloy layer, tin layer, and passivation film of a tinplate produced by the manufacturing method of the present application.

[0026] 1. Substrate; 2. Tin - iron alloy layer; 3. Tin layer; 4. Passivation film. Detailed Embodiments

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, 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 shall fall within the protection scope of the present invention.

[0028] An embodiment of the present application provides a method for manufacturing a tinplate, which includes electroplating, soft melting, quenching with water, and passivation on a substrate in sequence to obtain a tinplate. Among them,

[0029] In the electroplating process, metallic tin is used as the anode to form a tin layer on the surface of the substrate. The temperature of the electroplating solution is controlled at 35 - 55 °C, and the Fe 2+ concentration in the electroplating solution is not higher than 10 g / L;

[0030] In the soft melting process, the soft melting temperature is controlled at 240 - 290 °C;

[0031] In the quenching with water process, it includes spray quenching with water. The water flow rate M 水流量 satisfies: 0.022 × M 基板 × ΔT 基板 ≤ M 水流量 ≤ 0.026 × M 基板 × ΔT 基板 , and the target quenching temperature = -35 × H 基板 + 87; the quenching temperature is the target quenching temperature - 3 °C to the target quenching temperature + 3 °C.

[0032] In the above formula, M 基板 = W 基板 × H 基板 × V 基板 × ρ 铁 ; ΔT 基板 = T 软熔 - T 淬水 , where M 基板 is the mass of the substrate passing through any working point in the quenching with water process per unit time, W 基板 is the width of the substrate, H 基板 is the thickness of the substrate, V 基板 is the production speed of the substrate, ρ 铁 is the iron density, ρ 铁 = 7.85 × 10 3 kg / m 3 , ΔT 基板 is the temperature difference of the substrate, T 软熔 is the temperature of the substrate after soft melting, that is, the target soft melting temperature, T 淬水is the substrate temperature after quenching, i.e., the quenching target temperature. When calculating the quenching target temperature, only substitute the value when the substrate thickness is in mm. The quenching temperature is the temperature of the water used in the quenching process.

[0033] In this application, in the electroplating process, the electroplating solution is controlled at a suitable temperature to avoid the loosening of the tin layer caused by the reduction of cathode polarization. Fe 2+ Generated by the dissolution of the substrate in the electrolyte, controlling Fe 2+ content to avoid an increase in the number of pores on the surface of the tinplate, inhibit the growth of tin grains in the coating, resulting in a decrease in the corrosion resistance of the tinplate; it can also avoid the influence of too high Fe 2+ content on the conductivity of the electroplating solution.

[0034] After electroplating, through soft melting, an intermetallic compound FeSn2, i.e., a tin-iron alloy layer, is formed between the tin layer and the iron matrix. This alloy layer can effectively improve the corrosion resistance of the tinplate in cooperation with the tin layer. The soft melting temperature is controlled at 240 - 290 °C, which can not only ensure the effective melting of the tin layer but also avoid the transformation of the microscopic shape of the tin-iron alloy layer from needle-like to granular and the transformation of the composition from FeSn2 to FeSn, forming a harder and thicker FeSn alloy layer, which is not conducive to the processing performance of the tinplate. Controlling the soft melting temperature within the above range can form a tin-iron alloy layer with appropriate thickness and morphology.

[0035] After soft melting, through the quenching process, the bright surface of the soft-melted tinplate is rapidly cooled and solidified, preventing the surface from being damaged by the subsequent roller system and at the same time preventing the tin layer from being over-oxidized, forming a uniform and continuous coating surface.

[0036] A suitable spray water flow rate makes the heat of the tinplate entering the quenching process equal to the heat carried away by the sprayed water, that is, the mass of the substrate × the specific heat capacity of the substrate × the temperature difference of the substrate = the water flow rate × the specific heat capacity of the water × the temperature difference of the water. Therefore, the water flow rate = (the mass of the substrate × the specific heat capacity of the substrate × the temperature difference of the substrate) / (the specific heat capacity of the water × the temperature difference of the water). In the above formula, that is, M 基板 ×C 铁 ×ΔT 基板 =M 水流量 ×C 水 ×ΔT 水 where ΔT 水 The change in the quenching water temperature difference should ensure a target range of ±3 °C, that is, the maximum temperature difference change does not exceed ΔT 水 = 6 °C change range, C 铁 is the specific heat capacity of iron, C 铁 = 0.46×10 3 J / kg·°C, C 水 is the specific heat capacity of water, C 水 = 4.2×10 3J / kg·℃. When calculating, the margin and error in actual operation should also be considered. According to the actual situation and mass production experience, a compensation coefficient is introduced. The maximum compensation coefficient is 1.44 and the minimum compensation coefficient is 1.21. The water flow rate within this range can quickly reduce the substrate temperature, effectively improve surface defects such as quenching water spots, and at the same time make the tin layer dense and uniform, and form continuous acicular grains in the tin-iron alloy layer. In summary, the M water flow rate should be in the range of 1.21 (M 基板 ×C 铁 ×ΔT 基板 ) / (C 水 ×ΔT 水 )~1.44(M 基板 ×C 铁 ×ΔT 基板 ) / (C 水 ×ΔT 水 ). The constants in the above formula can be calculated as follows:

[0037] 1.44×0.46×10 3 J / kg·℃ / 4.2×10 3 J / kg·℃ / [3 - (-3)]℃≈0.026;

[0038] 1.21×0.46×10 3 J / kg·℃ / 4.2×10 3 J / kg·℃ / [3 - (-3)]℃≈0.022;

[0039] When spray quenching, if the water flow rate is higher than the previously set value, too much cooling water will be brought, resulting in too low cooling temperature and too fast cooling rate, which will cause the temperature of the tinned plate after soft melting to be too low, and the uniformity of the distribution of the tin layer and the tin-iron alloy layer will be affected, and non-uniform defects are likely to be formed. If it is lower than the set water flow rate range, the temperature of the tinned plate after quenching will be too high and the cooling rate will be slow, unable to achieve a proper cooling effect, affecting the density and uniformity of the tin layer morphology and the continuity of the tin-iron alloy layer. Even water marks in the shape of non-bright circles are likely to appear on the surface of the tin layer, forming defects such as quenching water spots.

[0040] Substrates with different thicknesses have different cooling requirements. Therefore, the quenching target temperature after quenching is set according to different substrate thicknesses.

[0041] In addition, the quenching temperature is controlled within a fluctuation of 3℃ above and below the quenching target temperature to avoid forming defects such as bubbles or quenching water spots, or affecting the uniformity and continuity of the tin layer and the tin-iron alloy layer, and ultimately affecting the corrosion resistance of the surface of the tinned plate.

[0042] In some embodiments, methanesulfonic acid is used as the electroplating solution, and the free acid concentration of methanesulfonic acid is 32~40 ml / L, and the Sn 2+ concentration is 16~20 g / L.

[0043] Controlling the appropriate concentration of free methanesulfonic acid and Sn 2+ concentration can ensure that the crystal nuclei have a relatively fast formation rate, the coating is finer, which is conducive to the formation of a dense and continuous coating with fine grains, thereby improving the corrosion resistance.

[0044] Furthermore, in the electroplating process, the forward speed of the substrate is 200 - 400 m / min to obtain a coating with an appropriate thickness.

[0045] Even further, in the electroplating process, the total current on one side of the substrate is 4.1 - 40.4 KA, and the cathode current efficiency is 75 - 95%. The total current on one side of the substrate refers to the total amount of current required to pass through the coating on one side during electroplating. The total electroplating current on one side \(I = a×W×V×G / η\), where \(a\) is a constant coefficient, \(W\) is the width of the substrate (mm), \(V\) is the production speed of the substrate (m / min), \(η\) is the cathode current efficiency (%), and \(G\) is the tin plating amount per unit area on one side (g / m 2 ). The cathode current efficiency \(η\) is the ratio of the mass of the actually deposited substance during electrolysis to the mass of the theoretically calculated deposited substance.

[0046] In some embodiments, the reflow process adopts a combined reflow method of resistance reflow and induction reflow. The alternating current frequency of the resistance reflow is 40 - 60 Hz, the induction reflow is high-frequency induction reflow, the current frequency is 200 - 350 kHz, and the reflow height is 2 - 5 m.

[0047] The resistance reflow provides a preheating temperature for the substrate, and the induction reflow provides an appropriate heating rate. Preheating the substrate and then increasing the heating rate is conducive to the formation of a dense alloy layer and avoids the damage to the corrosion resistance caused by grain growth.

[0048] In some embodiments, when spray quenching, quenching nozzles are respectively arranged on both sides of the substrate. Taking the horizontal plane as 0°, the angles of the quenching nozzles on both sides of the substrate are -45° to 45°.

[0049] During electroplating, reflow, and quenching, the substrate moves on the production line at a constant set speed. After the substrate is reflowed, it moves downward and is spray quenched. That is, when spray quenching, the substrate is relatively vertical. Quenching nozzles are arranged on both sides of the substrate to provide cooling water for both sides of the substrate at the same time, so that the temperature difference between both sides of the substrate is small and the temperature is uniform, so that fine and continuous tin-iron alloy layers and dense tin layers are formed on both sides of the substrate.

[0050] Setting the angle of the quenching nozzle within 45° above and below the horizontal plane can ensure the uniform distribution of the spray water flow and also ensure the stability of the substrate descent.

[0051] Preferably, the angles of the quenching nozzles on both sides of the substrate are -45°, -30°, -15°, 0°, 15°, 30° or 45°.

[0052] Furthermore, in the quenching process, after the spray quenching is completed, it also includes immersion quenching, and the temperature of the quenching tank for immersion quenching is the same as the quenching temperature.

[0053] The substrate is first spray-cooled and then immersed in the quenching tank for cooling. The water in the quenching tank can keep the substrate cooling continuous, so the process temperature range must be kept consistent with the spray water temperature range to achieve a better cooling effect. In addition, the surface of the substrate further cooled in the quenching tank is completely solidified, and surface defects are further eliminated, which is beneficial to improving the quality of the board surface.

[0054] In some embodiments, in the passivation process, electrochemical passivation is used, sodium dichromate solution is used as the passivation solution, the concentration of the sodium dichromate solution is 20-26 g / L, the pH value of the passivation solution is 4.2-4.7, the temperature of the passivation solution is 40-50°C, and the passivation charge density is 150-180 C / m 2 .

[0055] After the soft melting and quenching process, a passivation film with a complex structure containing hydrated oxides of chromium is formed on the surface of the tin layer, which prevents the tin layer from further oxidation and prevents the surface of the tinplate from discoloring and causing defects. At the same time, it can also improve the corrosion resistance and coating performance of the tinplate.

[0056] Reasonably control the concentration, charge density and temperature of the passivation solution to ensure that the passivation film has an appropriate thickness, avoid the passivation film being too thick, loose film, non-dense and uneven, which will easily cause micro cracks during the deformation process and affect the surface performance; it can also avoid the passivation film being too thin and unable to form an effective protective effect, which will damage the surface performance of the tinplate.

[0057] Controlling the pH value of the passivation solution within a reasonable range is conducive to the formation of the passivation film and maintaining a good structure of the passivation film, thereby improving the surface adhesion and corrosion resistance of the tinplate.

[0058] The present application also provides a tin-plated plate, which is manufactured by the above-mentioned manufacturing method, and includes a substrate and a tin-iron alloy layer, a tin layer and a passivation film sequentially attached to the surface of the substrate, and the tin content in the tin-plated plate is 0.9-2.8 g / m 2 , where the tin-iron alloy content is 0.4~0.8g / m 2 The difference in tin content between any two points in the tin-plated steel sheet is ≤0.2g / m 2 The chromium content in the passivation film is 4~6mg / m 2 .

[0059] After etching away the tin layer, it can be observed through an electron microscope that in the tin-iron alloy layer, the grains are in the shape of slender strips and are continuous, rather than forming clusters of grains or having large voids in the grains. The continuity of the grains gives the surface good corrosion resistance.

[0060] The technical solution of this application will be further described below in conjunction with some specific embodiments.

[0061] In this application, the production process does not change the composition of the steel plate. The compositions of the continuous annealing substrate and the electroplated tin plate are the same. The specific composition details of the examples and comparative examples are shown in Table 1.

[0062] Table 1 Compositions of continuous annealing substrate and electroplated tin plate

[0063]

[0064] A highly corrosion-resistant electroplated tin plate is obtained by subjecting a continuous annealing substrate with a thickness of 0.2 - 0.4 mm and a width of 800 - 1000 mm to surface cleaning, electroplating, soft melting, quenching, passivation, oiling, and coiling. According to the method of the present invention, the parameters of the continuous annealing substrate and the specific electroplating parameters are as shown in Table 2 below:

[0065] Table 2 Parameters of continuous annealing substrate and electroplating parameters

[0066]

[0067] The calculation of the spray water volume is based on 0.026×M 基板 ×ΔT 基板 ≥M 水流量 ≥0.022×M 基板 ×ΔT 基板 , that is, 0.026×W 基板 ×H 基板 ×V 基板 ×ρ 铁 ×(T 软熔 -T 淬水 )≥M 水流量 ≥0.022×W 基板 ×H 基板 ×V 基板 ×ρ 铁 ×(T 软熔 -T 淬水), the spray water flow rate range in Example 1 is 14.7 kg / s to 17.4 kg / s, the spray flow rate range in Example 2 is 27.6 kg / s to 32.7 kg / s, the spray water flow rate range in Example 3 is 43.9 kg / s to 51.9 kg / s, the spray water flow rate range in Example 4 is 67.5 kg / s to 79.7 kg / s, and the spray water flow rate range in Example 5 is 99.9 kg / s to 118.1 kg / s; the spray water flow rate range in Comparative Example 1 is 27.3 kg / s to 32.3 kg / s, the spray water flow rate range in Comparative Example 2 is 32.3 kg / s to 38.2 kg / s, the spray water flow rate range in Comparative Example 3 is 28.5 kg / s to 33.7 kg / s, and the spray water flow rate range in Comparative Example 4 is 24.6 kg / s to 29.1 kg / s. According to the inventive method and the above calculation results, the hot-dip and quenching process parameters of the examples and comparative examples are shown in Table 3 respectively.

[0068] Table 3 Hot-dip and Quenching Parameters

[0069]

[0070] After the hot-dip and quenching process according to the inventive method, it enters the passivation process, and a passivation film structure is covered on the surface of the tin layer. The passivation parameters and the surface tin content, tin-iron alloy layer amount, and passivation film amount of the final tinplate are shown in Table 4. Among them, the coulomb method in GB / T 1838-2008 is used to measure the tin content and tin-iron alloy content, and the chemical method in ASTM A623-77 is used to determine the chromium content in the passivation film.

[0071] Table 4 Passivation Parameters and Surface Layer Parameters

[0072]

[0073] It should be understood that although this specification is described according to the embodiments, not each embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0074] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of this application, and they are not used to limit the protection scope of this application. Any equivalent embodiments or changes made without departing from the technical spirit of this application should be included in the protection scope of this application.

Claims

1. A method for manufacturing a tinplate, characterized in that, The substrate is electroplated, fluxed, quenched with water, and passivated in sequence to obtain a tinplate. Among them, In the electroplating process, metallic tin is used as the anode to form a tin layer on the surface of the substrate. The temperature of the electroplating solution is controlled at 35~55°C, and the concentration of Fe 2+ in the electroplating solution is not higher than 10 g / L. in the fluxing process, the fluxing temperature is controlled at 240-290 °C; In the quenching process with water spraying, the water flow rate M of the water spraying 水流量 satisfies: 0.022 × M 基板 × ΔT 基板 ≤ M 水流量 ≤ 0.026 × M 基板 × ΔT 基板 , the quenching target temperature = -35 × H 基板 + 87, and the quenching temperature is the quenching target temperature - 3°C to the quenching target temperature + 3°C; Among them, M 基板 is the mass of the substrate passing through any working point in the quenching process per unit time, with the unit of kg / s, and ΔT 基板 is the temperature difference of the substrate before and after quenching, and H 基板 is the value of the substrate thickness, with the unit of mm; the fluxing process adopts a combined fluxing method of resistance fluxing and induction fluxing. The alternating current frequency of the resistance fluxing is 40-60 Hz, the induction fluxing is high-frequency induction fluxing, the current frequency is 200-350 kHz, and the fluxing height is 2-5 m.

2. The manufacturing method of the tinplate according to claim 1, characterized in that, Using methanesulfonic acid as the electroplating solution, the free acid concentration of methanesulfonic acid is 32 - 40 ml / L, and the Sn 2+ concentration is 16 - 20 g / L.

3. The manufacturing method of the tinplate according to claim 2, characterized in that, in the electroplating process, the forward speed of the substrate is 200-400 m / min.

4. The manufacturing method of the tinplate according to claim 3, characterized in that, in the electroplating process, the total current on one side of the substrate is 4.1-40.4 KA, and the cathode current efficiency is 75-95%.

5. The manufacturing method of the tinplate according to claim 1, characterized in that, When spraying and quenching with water, quenching nozzles are respectively arranged on both sides of the substrate. Taking the horizontal plane as 0°, the angles of the quenching nozzles on both sides of the substrate are -45° to 45°.

6. The manufacturing method of the tinplate according to claim 5, characterized in that, The angles of the quenching nozzles on both sides of the substrate are -45°, -30°, -15°, 0°, 15°, 30°, or 45°.

7. The manufacturing method of the tinplate according to claim 1, characterized in that, in the quenching process with water, after the spraying and quenching with water is completed, immersion quenching with water is further included, and the temperature of the quenching water tank for immersion quenching with water is the same as the quenching water temperature.

8. The manufacturing method of the tinplate according to claim 1, characterized in that, In the passivation process, electrochemical passivation is adopted, and sodium dichromate solution is used as the passivation solution. The concentration of the sodium dichromate solution is 20 - 26 g / L, the pH value of the passivation solution is 4.2 - 4.7, the temperature of the passivation solution is 40 - 50 °C, and the passivation charge density is 150 - 180 C / m 2 .

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