Tin-plated sheet and method for producing same

Abstract

The invention provides a tin plate and a manufacturing method thereof. According to the manufacturing method, a substrate is sequentially subjected to electroplating, soft melting, quenching and passivation to obtain the tin plate, tin is adopted as an anode, a tin layer is formed on the surface of the substrate, the temperature of an electroplating solution is controlled to be 35-55 DEG C, and the concentration of Fe < 2 + > in the electroplating solution is not higher than 10 g / L; the soft melting temperature is controlled to be 240-290 DEG C; the quenching procedure comprises spray quenching, the water flow M water flow of spray quenching meets the conditions that M water flow is larger than or equal to 0.022 * M substrate * delta T substrate and smaller than or equal to 0.026 * M substrate * delta T substrate, T quenching is equal to-35 * H substrate + 87, and the quenching temperature is T quenching + / -3 DEG C; wherein M substrate is the mass of the substrate passing through any working point in the quenching process in unit time, delta T substrate is the temperature difference before and after quenching of the substrate, and H substrate is the thickness value of the substrate. According to the tin plate obtained through the manufacturing method, the problems that in the prior art, after a tin plate is machined and deformed, surface gaps are many, and corrosion resistance is poor are solved.

Description

Technical Field

[0001] The present application relates to the technical field of alloy materials, and in particular to a tin-plated plate with high corrosion resistance and a manufacturing method thereof. Background Art

[0002] Tinplate is a thin steel plate coated with tin on both sides, mainly used to make the can body and top and bottom covers of beverage cans, food cans, and aerosol cans. With the development of production technology, the production line of high-end food and beverage cans has a high degree of automation, and the tinplate is subjected to a large amount of deformation in the key process of can making. Especially at the multiple neckings on the top of the can body, the base plate and the tin layer will undergo obvious deformation, which will make the original tin layer and alloy layer looser, resulting in the exposure of the steel matrix at the microscopic level.

[0003] like Figure 1 The figure in the figure is a schematic diagram of the tin-iron alloy layer, tin layer, and passivation film of tinplate produced by the current conventional process. The protective effect is discontinuous, so the probability of loose gaps appearing in the three protective layers at the same position will increase, thereby exposing the iron matrix. When the tinplate is used as a packaging container for food cans, the tin layer and the tin-iron alloy layer will produce polarization with the iron matrix under this medium. The more gaps there are in the protective layer, the greater the probability of forming continuous gaps, and the worse its corrosion resistance is when used as a food can, especially in complex deformation areas. After the loose gaps are deformed, the gaps become larger and the number increases, affecting the use effect.

[0004] The invention patent with patent publication number CN115558965A discloses a method for improving the corrosion resistance of the surface of low-tin tin-plated plates. The grain orientation of the substrate is controlled by annealing, the above-mentioned grain orientation is analyzed by XRD, and the surface characteristics are controlled by electroplating alkali washing. The Frostenberg tinning process is used to achieve tin layer deposition, and finally the strip is subjected to conventional soft melting and conventional passivation process treatment. This method can reduce the incidence of rust defects on the surface of low-tin tin-plated plates for manufacturers and users. However, this method requires frequent sampling and testing, and XRD microscopic characterization detection requires sample preparation, grinding and polishing, detection, and analysis. The entire cycle is relatively long and cannot meet the detection timeliness of industrial mass production. In addition, soft melting and passivation in this invention are conventional processes, which cannot meet the corrosion resistance of the aforementioned tin-plated plates at more complex deformations.

[0005] The invention patent with patent publication number CN114381779A discloses a tin-plated sheet with very low tin content and good corrosion resistance and a preparation method thereof. In the invention, the tin-plated sheet is subjected to chemical and electrochemical phosphating treatment in a phosphating solution to obtain a tin-plated sheet with a phosphating film; the tin-plated sheet with a phosphating film is passivated in a chromate passivation solution, which effectively improves the corrosion resistance of the tin-plated sheet with very low tin content. However, the invention requires equipment modification, adding chemical phosphating and electrochemical phosphating baths and drying equipment, and increasing additional production costs. At the same time, the chemical phosphating time in the invention 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 production requirements of high-speed electroplating tin. 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 patent publication number CN118703746A discloses an additive for PSA electroplating tin insoluble anode system and a method for producing tinplate. The method adopts the phenolsulfonic acid insoluble anode electroplating process system, and adds the additive obtained by mixing a certain proportion of sodium dithiopropane sulfonate, sodium gluconate, sodium bicarbonate and sodium carbonate into 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 phenolsulfonic acid electroplating process, and the plating solution is not easy to recycle and is prone to pollution. In addition, the invention does not describe in detail the specific methods and detailed parameters of the soft melting, quenching and other processes. Summary of the invention

[0007] The purpose of this application is to provide a method for manufacturing tinplate. The present invention conducts joint control from the key processes of electroplating, soft melting, quenching and passivation, fully considers the influence of each link on various surface formation layers in production, controls the relevant parameters in each process, so that a tin-iron alloy layer with elongated grains and continuity is formed on the surfaces of both sides of the substrate, and a tin layer with fine, dense and uniform grains is formed on the tin-iron alloy layer. The problem of many surface gaps and poor corrosion resistance of tinplate after processing and deformation in the prior art is solved, and the needs of complex processing and canning are met.

[0008] In order to achieve one of the above-mentioned purposes of the invention, an embodiment of the present application provides a method for manufacturing a tinplate, wherein a substrate is subjected to electroplating, reflow, quenching, and passivation in sequence to obtain a tinplate, wherein: In the electroplating process, metal 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℃. 2+ The concentration is not higher than 10g / L; In the reflow process, the reflow temperature is controlled at 240~290℃; The quenching process includes spray quenching, and the water flow rate M of the spray quenching is 水流量 Satisfy: 0.022×M 基板 ×ΔT 基板 ≤M 水流量 ≤0.026×M 基板 ×ΔT 基板 , quenching water target temperature = -35 × H 基板 +87; quenching temperature is quenching target temperature -3℃~quenching target temperature +3℃; Among them, 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 before and after quenching of the substrate, H 基板 The value of substrate thickness in mm.

[0009] As a further improvement of an embodiment of the present application, methanesulfonic acid is used as the electroplating solution, and the concentration of methanesulfonic acid free acid is 32-40 ml / L, Sn 2+ The concentration is 16~20g / L.

[0010] As a further improvement of an embodiment of the present application, during the electroplating process, the forward speed of the substrate is 200-400 m / min.

[0011] As a further improvement of an embodiment of the present application, in the electroplating process, the total current of a single side of the substrate is 4.1~40.4KA, and the cathode current efficiency is 75~95%.

[0012] As a further improvement of one embodiment of the present application, the soft melting process adopts a combined soft melting method of resistance soft melting and induction soft melting, the resistance soft melting AC frequency is 40~60Hz, the induction soft melting is high-frequency induction soft melting, the current frequency is 200~350kHz, and the soft melting height is 2~5m.

[0013] As a further improvement of an embodiment of the present application, quenching nozzles are respectively arranged on both sides of the substrate during spray quenching, with the horizontal plane being 0°, and the angles of the quenching nozzles on both sides of the substrate being -45°~45°.

[0014] As a further improvement of one 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°.

[0015] As a further improvement of one embodiment of the present application, 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.

[0016] As a further improvement of one 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 .

[0017] The present application also provides a tin-plated plate, comprising a substrate and a tin-iron alloy layer, a tin layer and a passivation film sequentially attached to the surface of the substrate, wherein 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 .

[0018] One or more technical solutions provided by this application have at least the following technical effects or advantages: In the manufacturing method of tinplate provided in the present application, the whole process is jointly controlled from key processes such as electroplating, soft melting, and quenching, and full consideration is given to the influence of each link on various surface formation layers during production, so that a tin-iron alloy layer with slender grains and continuity is formed on the surfaces of both sides of the tinplate, and a tin layer with fine, dense and uniform grains is formed on the tin-iron alloy layer; thereby, a multi-layer dense protective layer is formed on the substrate, further improving the corrosion resistance of the tinplate at multiple necking and deformation sites, and meeting the surface performance requirements of the tinplate under complex processing conditions with large deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the tin-iron alloy layer, tin layer and passivation film of the tinplate produced by conventional process.

[0020] Figure 2 It is a schematic structural diagram of the tin-iron alloy layer, the tin layer and the passivation film of the tin-plated plate produced by the manufacturing method of the present application.

[0021] 1. Substrate; 2. Tin-iron alloy layer; 3. Tin layer; 4. Passivation film. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The present application provides a method for manufacturing a tinplate, wherein a substrate is subjected to electroplating, reflow, quenching, and passivation in sequence to obtain a tinplate, wherein: In the electroplating process, metal 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℃. 2+ The concentration is not higher than 10g / L; In the reflow process, the reflow temperature is controlled at 240~290℃; The quenching process includes spray quenching, and the water flow rate M of the spray quenching is 水流量 Satisfy: 0.022×M 基板 ×ΔT 基板 ≤M 水流量 ≤0.026×M 基板 ×ΔT 基板 , quenching water target temperature = -35 × H 基板 +87; the quenching temperature is the quenching target temperature -3℃ ~ quenching target temperature +3℃.

[0024] 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 process per unit time, W 基板 is the width of the substrate, H 基板 is the substrate thickness, V 基板 is the substrate production speed, ρ 铁 is the density of iron, ρ 铁 =7.85×10 3 kg / m 3 , ΔT 基板 is the temperature difference of the substrate, T 软熔 is the substrate temperature after reflow, i.e. the reflow target temperature, T 淬水 The substrate temperature after quenching, i.e., the quenching target temperature. When calculating the quenching target temperature, only the value when the substrate thickness is in mm is substituted. The quenching temperature is the temperature of the water used in the quenching process.

[0025] In the present application, in the electroplating process, the electroplating solution is controlled at a suitable temperature to avoid the reduction of cathode polarization and the resulting loosening of the tin layer. 2+ The substrate is dissolved in the electrolyte to generate and control the Fe 2+ The content avoids the increase of pores on the surface of the tinplate, inhibits the growth of tin grains in the coating, and causes the corrosion resistance of the tinplate to decrease; it can also avoid Fe 2+Too high a content will affect the conductivity of the plating solution.

[0026] After electroplating, the tin layer and the iron matrix are melted to form an intermetallic compound FeSn2, i.e., a tin-iron alloy layer. This alloy layer can cooperate with the tin layer to effectively improve the corrosion resistance of the tin-plated sheet. Controlling the melt temperature to 240-290°C can not only ensure the effective melting of the tin layer, but also prevent the microscopic shape of the tin-iron alloy layer from changing from needle-like to granular, and the composition from FeSn2 to FeSn, forming a harder and thicker FeSn alloy layer, which is not conducive to the processing performance of the tin-plated sheet. If the melt temperature is controlled at the above temperature, a tin-iron alloy layer with suitable thickness and morphology can be formed.

[0027] After the reflow is completed, the bright surface of the tinplate after reflow is quickly cooled and solidified through the quenching process to prevent the surface from being damaged by the rollers in the subsequent process, and to prevent the tin layer from being over-oxidized, forming a uniform and continuous coating surface.

[0028] The appropriate spray water flow rate makes the heat of the tinplate entering the quenching process equal to the heat taken 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 = water flow rate × the specific heat capacity of water × the temperature difference of water. Therefore, water flow rate = (mass of the substrate × the specific heat capacity of the substrate × the temperature difference of the substrate) / (specific heat capacity of water × the temperature difference of water). In the above formula, M 基板 ×C 铁 ×ΔT 基板 =M 水流量 ×C 水 ×ΔT 水 , where ΔT 水 The quenching water temperature difference should ensure the target range of ±3°C, that is, the maximum temperature difference does not exceed ΔT 水 =6℃ change range, C 铁 is the specific heat capacity of iron, C 铁 =0.46×10 3 J / kg·℃,C 水 is the specific heat capacity of water, C 水 =4.2×10 3 J / kg·℃, and in the calculation, the margin and error in actual operation should also be considered. According to the actual situation and batch 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 spots, and at the same time make the tin layer dense and uniform, so that the tin-iron alloy layer forms continuous needle-shaped grains. In summary, the water flow rate M should be between 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 ) range. The constants in the above formula can be calculated as: 1.44×0.46×10 3 J / kg·℃ / 4.2×10 3 J / kg·℃ / [3-(-3)]℃≈0.026; 1.21×0.46×10 3 J / kg·℃ / 4.2×10 3 J / kg·℃ / [3-(-3)]℃≈0.022; During spray quenching, if the water flow rate is higher than the aforementioned setting, too much cooling water will be brought in, resulting in too low cooling temperature and too fast cooling rate, which will lead to too low temperature of the tinplate after soft melting, and the uniformity of the distribution of the tin layer and the tin-iron alloy layer will be affected, and uneven defects will be easily formed; if it is lower than the set water flow rate range, the temperature of the tinplate after quenching will be too high, the cooling rate will be slow, and the appropriate cooling effect cannot be achieved, affecting the dense uniformity of the tin layer morphology and the continuity of the tin-iron alloy layer, and even the surface of the tin layer will be prone to produce non-bright circle water marks, forming defects such as quenching spots.

[0029] Substrates of different thicknesses have different cooling requirements, and thus the target quenching temperature after quenching is set according to the different substrate thicknesses.

[0030] In addition, the quenching temperature is controlled within 3°C of the quenching target temperature to avoid the formation of defects such as bubbles or quenching spots, or affect the uniformity and continuity of the tin layer and tin-iron alloy layer, ultimately affecting the corrosion resistance of the tinplate surface.

[0031] In some embodiments, methanesulfonic acid is used as the plating solution, and the concentration of methanesulfonic acid free acid is 32-40 ml / L. 2+ The concentration is 16~20g / L.

[0032] Control the appropriate methanesulfonic acid free acid concentration and Sn 2+ The concentration can ensure that the crystal nucleus has a faster generation rate and the coating is finer, which is conducive to the formation of a dense, continuous, and fine-grained coating, thereby improving corrosion resistance.

[0033] Furthermore, during the electroplating process, the substrate is advanced at a speed of 200-400 m / min to obtain a coating of suitable thickness.

[0034] Furthermore, in the electroplating process, the total current of a single side of the substrate is 4.1~40.4KA, and the cathode current efficiency is 75~95%. The total current of a single side of the substrate refers to the total current required to pass through the single-sided coating during the electroplating process. The total current of electroplating on a single side I=a×W×V×G / η, a is a constant coefficient, W is the substrate width (mm), V is the substrate production speed (m / min), η is the cathode current efficiency (%), G is the single-sided tin plating amount (g / m 2 ). The cathode current efficiency η is the ratio of the mass of the actual precipitated substance during electrolysis to the mass of the theoretically calculated precipitated substance.

[0035] In some embodiments, the soft melting process adopts a combined soft melting method of resistance soft melting and induction soft melting, the resistance soft melting AC frequency is 40~60Hz, the induction soft melting is high frequency induction soft melting, the current frequency is 200~350kHz, and the soft melting height is 2~5m.

[0036] Resistance melting is used to provide the preheating temperature for the substrate, and induction melting provides the appropriate heating rate. After the substrate is preheated, the heating rate is increased to form a dense alloy layer and avoid grain growth and damage to corrosion resistance.

[0037] In some embodiments, quenching nozzles are respectively arranged on both sides of the substrate during spray quenching, with the horizontal plane being 0°, and the angles of the quenching nozzles on both sides of the substrate being -45°~45°.

[0038] During the electroplating, reflow and quenching process, the substrate moves on the production line at a constant set speed. After the substrate is reflowed, it moves downward and sprays and quenches. That is, during the spray quenching, the substrate is relatively vertical. Quenching nozzles are set on both sides of the substrate, and cooling water is provided to both sides of the substrate at the same time, so that the temperature difference on both sides of the substrate is small and the temperature is uniform, so that a fine and continuous tin-iron alloy layer and a dense tin layer are formed on both sides of the substrate.

[0039] Setting the angle of the quenching nozzle within 45° above and below the horizontal plane can ensure uniform distribution of the spray water flow and also ensure the stability of the substrate descent.

[0040] Preferably, the angles of the quenching nozzles on both sides of the substrate are -45°, -30°, -15°, 0°, 15°, 30° or 45°.

[0041] 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.

[0042] 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.

[0043] 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 .

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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 .

[0048] After etching away the tin layer, the electron microscope was used to observe the tin-iron alloy layer. The grains were long and thin and continuous, rather than clustered together or with large gaps in the grains. The continuity of the grains gave the surface good corrosion resistance.

[0049] The technical solution of the present application is further described below in conjunction with some specific embodiments.

[0050] The production process in this application does not change the composition of the steel plate, the composition of the continuous annealing substrate and the electroplated tin plate is consistent, and the specific composition details of the embodiment and the comparative example are shown in Table 1.

[0051] Table 1 Composition of continuous annealing substrate and electroplated tinplate

[0052] A high corrosion-resistant tinplate is obtained by surface cleaning, electroplating, reflowing, quenching, passivation, oiling and coiling a continuous annealing substrate with a thickness of 0.2-0.4 mm and a width of 800-1000 mm. According to the method of the present invention, the parameters of the continuous annealing substrate and the specific parameters of the electroplating are shown in Table 2 below: Table 2 Continuous annealing substrate parameters and electroplating parameters

[0053] 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 of Example 1 is 14.7kg / s~17.4kg / s, the spray flow rate range of Example 2 is 27.6kg / s~32.7kg / s, the spray water flow rate range of Example 3 is 43.9kg / s~51.9kg / s, the spray water flow rate range of Example 4 is 67.5kg / s~79.7kg / s, and the spray water flow rate range of Example 5 is 99.9kg / s~118.1kg / s; the spray water flow rate range of Comparative Example 1 is 27.3kg / s~32.3kg / s, the spray water flow rate range of Comparative Example 2 is 32.3kg / s~38.2kg / s, the spray water flow rate range of Comparative Example 3 is 28.5kg / s~33.7kg / s, and the spray water flow rate range of Comparative Example 4 is 24.6kg / s~29.1kg / s. According to the inventive method and the above calculation results, the reflow and quenching process parameters of the embodiment and the comparative example are shown in Table 3 respectively.

[0054] Table 3 Soft melting and quenching parameters

[0055] After the soft melting and quenching process according to the inventive method, the passivation process is entered, and a passivation film structure is covered on the surface of the tin layer. The passivation parameters and the final tin content on the surface of the tin-plated plate, the amount of the tin-iron alloy layer, and the amount of the passivation film are shown in Table 4. Among them, the coulometric method in GB / T 1838-2008 is used to measure the tin content and the amount of the tin-iron alloy, and the chemical method in ASTM A623-77 is used to determine the chromium content in the passivation film.

[0056] Table 4 Passivation parameters and surface parameters

[0057] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0058] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present application. They are not intended to limit the scope of protection of the present application. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present application should be included in the scope of protection of the present application.

Claims

1. A method for manufacturing a tinplate, characterized in that: The substrate is subjected to electroplating, reflow, quenching and passivation in sequence to obtain a tin-plated plate, wherein: In the electroplating process, metal 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℃. 2+ The concentration is not higher than 10g / L; In the reflow process, the reflow temperature is controlled at 240~290℃; The quenching process includes spray quenching, and the water flow rate M of the spray quenching is 水流量 Satisfy: 0.022×M 基板 ×ΔT 基板 ≤M 水流量 ≤0.026×M 基板 ×ΔT 基板 , quenching water target temperature = -35 × H 基板 +87, quenching temperature is quenching target temperature -3℃~quenching target temperature +3℃; Among them, 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 before and after quenching of the substrate, H 基板 The value of substrate thickness in mm.

2. The method for manufacturing a tinplate according to claim 1, characterized in that: Methanesulfonic acid is used as the plating solution, and the free acid concentration of methanesulfonic acid is 32~40ml / L. 2+ The concentration is 16~20g / L.

3. The method for manufacturing a tinplate according to claim 2, characterized in that: During the electroplating process, the substrate moves at a speed of 200 to 400 m / min.

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

5. The method for manufacturing a tinplate according to claim 1, characterized in that: The soft melting process adopts a combined soft melting method of resistance soft melting and induction soft melting. The resistance soft melting AC frequency is 40~60Hz, the induction soft melting is high-frequency induction soft melting, the current frequency is 200~350kHz, and the soft melting height is 2~5m.

6. The method for manufacturing a tinplate according to claim 1, characterized in that: When spraying quenching, quenching nozzles are respectively set on both sides of the substrate. With the horizontal plane as 0°, the angles of the quenching nozzles on both sides of the substrate are -45°~45°.

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

8. The method for manufacturing a tinplate according to claim 1, characterized in that: 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.

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

10. A tinplate, characterized in that: It 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 0.9~2.8g / 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 .

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