Manufacturing method of tin-plated steel sheet

Abstract

The present application relates to the technical field of steel sheet manufacturing, and more particularly to a method for manufacturing a tin-plated steel sheet. In the method for manufacturing a tin-plated steel sheet, in the step of flattening a substrate, flattening by a double frame is adopted, the work roll of the first frame has a surface roughness value Ra of 1.6-1.7 μm and a rolling force of 5000-6000 kN, and the work roll of the second frame has a surface roughness value Ra of 0.5-0.6 μm and a rolling force of 3000-4000 kN, and in the step of electroplating the substrate, the Sn of the electroplating solution is 2+ The concentration is 14-19 mL / L. In the step of passivating the substrate, the passivation solution has a temperature of 41-43° C., a pH value of 4.4-4.6, a concentration of 16-18 g / L, and a charge density of 120-180 C / m 2 In the present invention, both the corrosion resistance and adhesion meet the requirements for use through the synergistic effect of each process parameter.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority to a Chinese patent application bearing application number 202211636408.9 and entitled "Method for manufacturing tin-plated steel sheet" filed with the China Patent Office on December 20, 2022, the entire contents of which are incorporated herein by reference.

[0002] [Technical field] The present application relates to the technical field of steel sheet manufacturing, and in particular to a method for manufacturing tin-plated steel sheet. [Background technology]

[0003] Tin-plated steel sheets are environmentally friendly and safe packaging materials that are widely used for the bodies and top lids of beverage cans, food cans, aerosol cans, etc. A conventional method for producing tin-plated steel sheets involves alkaline cleaning of a substrate, continuous annealing, flattening, trimming, oiling, and winding, followed by alkaline cleaning, pickling, electroplating, fluxing, reflow, passivation, oiling, and winding of the substrate to obtain a tin-plated steel sheet.

[0004] Can bodies made of tin-plated steel sheets often need to be painted on the inside and outside to achieve protective and decorative effects. In particular, food cans and beverage cans have very high requirements for paint adhesion, usually requiring at least level 2. China Patent No. 107904638 discloses a method for producing high adhesion electroplated tin sheets by controlling and optimizing the passivation process of tin-plated steel sheets, improving the adhesion to level 1. However, this method limits the mass content of Cr(OH)3 in the passive film structure to less than 40%. Although the adhesion is ensured, the corrosion resistance of the resulting tin-plated steel sheet will deteriorate if the mass content of Cr(OH)3 is reduced. When industrial mass production is carried out, some batches may have unacceptable corrosion resistance, which will affect the normal use of tin-plated steel sheets. Summary of the Invention [Problem to be solved by the invention]

[0005] The technical problem to be solved by the present application is to solve the defect in the prior art that the compatibility of corrosion resistance and adhesion of tin-plated steel sheets does not satisfy the requirements for use. [Means for solving the problem]

[0006] In order to solve the above technical problems, the technical solutions used in this application are as follows:

[0007] A method for producing a tin-plated steel sheet, comprising the steps of: In the step of planarizing the substrate, a double-frame planarization is adopted, and the distance between the work roll of the first frame and the work roll of the second frame during use is 600 km or less, the work roll of the first frame has a surface roughness value Ra of 1.6 to 1.7 μm and a rolling force of 5000 to 6000 kN, and the work roll of the second frame has a surface roughness value Ra of 0.5 to 0.6 μm and a rolling force of 3000 to 4000 kN; In the step of electroplating the substrate, the Sn 2+ The concentration is 14-19 mL / L. In the step of passivating the substrate, the passivation solution has a temperature of 41-43°C, a pH value of 4.4-4.6, a concentration of 16-18g / L, and a charge density of 120-180C / m 2 and 120 C / m when the surface roughness value Ra and the number of peaks Rpc of the substrate satisfy 115≦100×Ra+Rpc<130 2 ≦ Passivation charge density<150C / m 2 and 150 C / m when the surface roughness value Ra and the number of peaks Rpc of the substrate satisfy 130≦100×Ra+Rpc≦155 2 ≦Passivation charge density≦180C / m 2 It is.

[0008] Furthermore, the flattening elongation rate in the flattening step is 1 to 1.8%.

[0009] Furthermore, in the planarization step, When the distance during use of the work roll of the first frame is 50 km or less, the rolling force of the work roll of the first frame is 5000 kN≦5100 kN; In the case where 50 km < the distance when the work roll of the first frame is used ≦ 100 km, 5100 kN < the rolling force of the work roll of the first frame ≦ 5200 kN, In the case where 100 km < the distance when the work roll of the first frame is used ≦ 500 km, 5200 kN < the rolling force of the work roll of the first frame ≦ 5700 kN, In the case where 500 km<distance when the work rolls of the first frame are used≦600 km, 5700 kN<rolling force of the work rolls of the first frame≦6000 kN.

[0010] Furthermore, in the planarization step, When the distance when the work roll of the second frame is used is 50 km or less, the rolling force of the work roll of the second frame is 3000 kN≦3200 kN; In the case where 50 km < the distance when the work roll of the second frame is used ≦ 100 km, 3200 < the rolling force of the work roll of the second frame ≦ 3400 kN, In the case where 100 km < the distance when the work roll of the second frame is used ≦ 500 km, 3400 kN < the rolling force of the work roll of the second frame ≦ 3800 kN, In the case where 500 km<distance when the work rolls of the second frame are used≦600 km, 3800 kN<rolling force of the work rolls of the second frame≦4000 kN.

[0011] Furthermore, after the flattening step is completed, the substrate has a surface roughness value Ra of 0.5 to 0.6 μm and a peak number Rpc of 65 to 95 cm -1 It is.

[0012] Furthermore, in the electroplating step, the electroplating method is a methanesulfonic acid electroplating process, and during electroplating, the substrate passes through the electroplating bath at a speed of 200-300 m / min.

[0013] Furthermore, in the electroplating step, the temperature of the electroplating solution is 35 to 55°C.

[0014] Furthermore, in the electroplating step, the concentration of free acid in the electroplating solution is 28 to 38 mL / L; And / or, the single-sided electroplating total current is 5.3-11.6KA, and the cathode current efficiency is 80-90%.

[0015] Furthermore, a Cr(OH)3 / Cr2O3 passivation film is formed on the surface of the substrate that has undergone the passivation step; The mass content ratio of Cr(OH)3 to Cr2O3 in the passivation film is 1 to 1.5.

[0016] Furthermore, the method further includes a continuous annealing step before the planarization, and the substrate that has undergone the continuous annealing step has a tensile strength of 385-485 MPa.

[0017] Furthermore, the passivation solution is a sodium dichromate solution. Effect of the Invention

[0018] The technical solution of the present application has the following advantages:

[0019] 1. In the manufacturing method of the tin-plated steel sheet according to the present invention, the surface roughness value and rolling force of the work roll of the frame are limited in the flattening step, the electroplating solution is adjusted in the electroplating step, and the charge density of the passivation solution and passivation is limited in the passivation step. The synergistic effect of each process parameter improves the adhesion of the tin-plated steel sheet, ensures the corrosion resistance of the tin-plated steel sheet, and both the corrosion resistance and adhesion of the tin-plated steel sheet meet the requirements for use.

[0020] 2. In the manufacturing method of the tin-plated steel sheet according to the present application, the decrease in the surface roughness of the work roll during actual use is fully taken into consideration, and the decrease in the surface roughness of the work roll directly affects the surface roughness value of the flattened substrate. In the present application, the working distance of the work rolls is combined to formulate a plan for combining the rolls used for flattening and a plan for utilizing the rolling force, so as to give the substrate an appropriate surface roughness value Ra and peak number Rpc, thereby giving the substrate an appropriate surface condition and laying the foundation for producing a high adhesion tin-plated steel sheet.

[0021] 3. In the conventional manufacturing method of tin-plated steel sheets, the passive film mainly contains Cr(OH)3 and Cr2O3, in addition to which there are very small amounts of metallic Cr and Cr 6+ When the mass content of metal Cr(OH)3 in the passivation film is reduced, the adhesion is effectively improved, but when the mass content of Cr(OH)3 is too low, the corrosion resistance of the tin-plated steel sheet is reduced. In the present application, the adhesion and corrosion resistance of the tin-plated steel sheet are made compatible through the specific process parameters of the planarization, electroplating, and passivation processes, so that both its corrosion resistance and adhesion meet the requirements of use. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The following examples are provided for a better understanding of the present application, and are not limited to the above-mentioned best embodiment, and are not intended to limit the content and scope of protection of the present application. Any products that are the same or similar to those of the present application obtained by combining the suggestions of the present application or the features of the present application with other prior art are within the scope of protection of the present application.

[0023] Unless specific experimental procedures or conditions are specified in the examples, they may be carried out according to the operations or conditions of the general experimental procedures described in the literature in the field. The manufacturers of the reagents or instruments used are not specified, and all are general reagent products available commercially.

[0024] In the manufacturing method of the tin-plated steel sheet according to the present invention, the roll usage schedule of the flattening step is adjusted, the rolling schedule is formulated according to the working roll usage distance, and the electroplating and passivation process are optimized, and all other manufacturing steps are well known in the art.

[0025] The chemical compositions of the low carbon cold rolled hard steel sheets used in the examples of this application are shown in Table 1.

[0026] [Table 1]

[0027] Example 1 This embodiment provides a method for producing a tin-plated steel sheet, which includes the steps of sequentially performing alkaline cleaning, continuous annealing, planarization, trimming, oiling, and winding of a substrate, and then performing alkaline cleaning, pickling, electroplating, fluxing, reflow, passivation, oiling, and winding of the substrate to obtain a tin-plated steel sheet. The substrate is a low carbon cold rolled hard steel plate with a thickness of 0.20 mm and a width of 820 mm. After normal alkaline cleaning, the substrate is subjected to continuous annealing. The tensile strength of the substrate after annealing is 423 MPa. The flattening step is flattening by double frame, the work roll of the first frame has a surface roughness value of 1.6 μm, a distance in use of 50 km, a rolling force of 5100 kN, the work roll of the second frame has a surface roughness value of 0.5 μm, a distance in use of 0 km, a rolling force of 3000 kN, and a flattening elongation of 1.1%. After flattening, the substrate was detected to have a surface roughness value Ra of 0.6 μm and a peak number Rpc of 95 cm -1 Therefore, the value of 100×Ra+Rpc for the board is 155. The width of the board after trimming is 800 mm. The electroplating method in the electroplating step is a methanesulfonic acid electroplating process. During electroplating, the substrate passes through the electroplating tank at a speed of 250 m / min. The temperature of the electroplating solution is 40° C., and the concentration of free acid in the electroplating solution is 30 mL / L. 2+The concentration of is 15 mL / L, the single-sided electroplating total current is 7.27 KA, and the cathode current efficiency is 82%. In the passivation step, the passivation solution is sodium dichromate solution, the temperature of the passivation solution is 42°C, the pH value is 4.5, the concentration is 16g / L, and the charge density of the passivation solution is 150C / m 2 A Cr(OH)3 / Cr2O3 passivation film is formed on the surface of the substrate after the passivation step, and the mass content ratio of Cr(OH)3 and Cr2O3 in the passivation film is 1.27.

[0028] Example 2 This embodiment provides a method for producing a tin-plated steel sheet, which includes the steps of sequentially performing alkaline cleaning, continuous annealing, planarization, trimming, oiling, and winding of a substrate, and then performing alkaline cleaning, pickling, electroplating, fluxing, reflow, passivation, oiling, and winding of the substrate to obtain a tin-plated steel sheet. The substrate is a low carbon cold rolled hard steel plate with a thickness of 0.23 mm and a width of 878 mm. After normal alkaline cleaning, the substrate is subjected to continuous annealing. The tensile strength of the substrate after annealing is 435 MPa. The flattening step is flattening by double frame, the work roll of the first frame has a surface roughness value of 1.65 μm, a distance in use of 300 km, a rolling force of 5450 kN, the work roll of the second frame has a surface roughness value of 0.56 μm, a distance in use of 300 km, a rolling force of 3600 kN, and a flattening elongation of 1.25%. After flattening, the substrate was detected to have a surface roughness value Ra of 0.59 μm and a peak number Rpc of 86 cm. -1 Therefore, the value of 100×Ra+Rpc for the substrate is 145. The width of the board after trimming is 858 mm. The electroplating method in the electroplating step is a methanesulfonic acid electroplating process. During electroplating, the substrate passes through the electroplating tank at a speed of 300 m / min. The temperature of the electroplating solution is 43°C. The concentration of free acid in the electroplating solution is 35 mL / L. 2+The concentration of is 17 mL / L, the single-sided electroplating total current is 9.47 KA, and the cathode current efficiency is 81%. In the passivation step, the passivation solution is sodium dichromate solution, the temperature of the passivation solution is 41°C, the pH value is 4.5, the concentration is 17g / L, and the charge density of the passivation solution is 180C / m 2 A Cr(OH)3 / Cr2O3 passivation film is formed on the surface of the substrate that has undergone the passivation step, and the mass content ratio of Cr(OH)3 and Cr2O3 in the passivation film is 1.46.

[0029] Example 3 This embodiment provides a method for producing a tin-plated steel sheet, which includes the steps of sequentially performing alkaline cleaning, continuous annealing, planarization, trimming, oiling, and winding of a substrate, and then performing alkaline cleaning, pickling, electroplating, fluxing, reflow, passivation, oiling, and winding of the substrate to obtain a tin-plated steel sheet. The substrate is a low carbon cold rolled hard steel plate having a thickness of 0.30 mm and a width of 943 mm. After normal alkaline cleaning, the substrate is subjected to continuous annealing. The tensile strength of the substrate after annealing is 443 MPa. The flattening step is flattening by double frame, the work roll of the first frame has a surface roughness value of 1.65 μm, a distance in use of 600 km, a rolling force of 6000 kN, the work roll of the second frame has a surface roughness value of 0.53 μm, a distance in use of 600 km, a rolling force of 4000 kN, and a flattening elongation of 1.4%. After flattening, the substrate was detected to have a surface roughness value Ra of 0.6 μm and a peak number Rpc of 88 cm -1 Therefore, the value of 100×Ra+Rpc for the board is 148. The width of the board after trimming is 923 mm. The electroplating method in the electroplating step is a methanesulfonic acid electroplating process. During electroplating, the substrate passes through the electroplating tank at a speed of 250 m / min. The temperature of the electroplating solution is 46°C. The concentration of free acid in the electroplating solution is 36 mL / L. 2+The concentration of is 18 mL / L, the single-sided electroplating total current is 8.59 KA, and the cathode current efficiency is 80%. In the passivation step, the passivation solution is sodium dichromate solution, the temperature of the passivation solution is 42°C, the pH value is 4.5, the concentration is 18g / L, and the charge density of the passivation solution is 180C / m 2 A Cr(OH)3 / Cr2O3 passivation film is formed on the surface of the substrate that has undergone the passivation step, and the mass content ratio of Cr(OH)3 and Cr2O3 in the passivation film is 1.5.

[0030] Example 4 This embodiment provides a method for producing a tin-plated steel sheet, which includes the steps of sequentially performing alkaline cleaning, continuous annealing, planarization, trimming, oiling, and winding of a substrate, and then performing alkaline cleaning, pickling, electroplating, fluxing, reflow, passivation, oiling, and winding of the substrate to obtain a tin-plated steel sheet. The substrate is a low carbon cold rolled hard steel plate having a thickness of 0.17 mm and a width of 848 mm. After normal alkaline cleaning, the substrate is subjected to continuous annealing. The tensile strength of the substrate after annealing is 462 MPa. The flattening step is flattening by double frame, the work roll of the first frame has a surface roughness value of 1.6 μm, a distance in use of 75 km, a rolling force of 5150 kN, the work roll of the second frame has a surface roughness value of 0.6 μm, a distance in use of 550 km, a rolling force of 3900 kN, and a flattening elongation of 1.28%. After flattening, the substrate was detected to have a surface roughness value Ra of 0.53 μm and a peak number Rpc of 80 cm -1 Therefore, the value of 100×Ra+Rpc for the substrate is 133. The width of the board after trimming is 823 mm. The electroplating method in the electroplating step is a methanesulfonic acid electroplating process. During electroplating, the substrate passes through the electroplating tank at a speed of 280 m / min. The temperature of the electroplating solution is 48°C. The concentration of free acid in the electroplating solution is 38 mL / L. 2+The concentration of is 19 mL / L, the single-sided electroplating total current is 7.94 KA, and the cathode current efficiency is 85%. In the passivation step, the passivation solution is sodium dichromate solution, the temperature of the passivation solution is 43°C, the pH value is 4.6, the concentration is 17g / L, and the charge density of the passivation solution is 160C / m 2 A Cr(OH)3 / Cr2O3 passivation film is formed on the surface of the substrate that has undergone the passivation step, and the mass content ratio of Cr(OH)3 and Cr2O3 in the passivation film is 1.4.

[0031] Example 5 This embodiment provides a method for producing a tin-plated steel sheet, which includes the steps of sequentially performing alkaline cleaning, continuous annealing, planarization, trimming, oiling, and winding of a substrate, and then performing alkaline cleaning, pickling, electroplating, fluxing, reflow, passivation, oiling, and winding of the substrate to obtain a tin-plated steel sheet. The substrate is a low carbon cold rolled hard steel plate having a thickness of 0.40 mm and a width of 1055 mm. After normal alkaline cleaning, the substrate is subjected to continuous annealing. The tensile strength of the substrate after annealing is 392 MPa. The flattening step is flattening by double frame, the work roll of the first frame has a surface roughness value of 1.7 μm, a distance in use of 0 km, a rolling force of 5000 kN, the work roll of the second frame has a surface roughness value of 0.55 μm, a distance in use of 100 km, a rolling force of 3400 kN, and a flattening elongation of 1.15%. After flattening, the substrate was detected to have a surface roughness value Ra of 0.56 μm and a peak number Rpc of 75 cm -1 Therefore, the value of 100×Ra+Rpc for the substrate is 131. The width of the board after trimming is 1035 mm. The electroplating method in the electroplating step is a methanesulfonic acid electroplating process. During electroplating, the substrate passes through the electroplating tank at a speed of 300 m / min. The temperature of the electroplating solution is 45°C. The concentration of free acid in the electroplating solution is 36 mL / L. 2+The concentration of is 18 mL / L, the single-sided electroplating total current is 11.6 KA, and the cathode current efficiency is 80%. In the passivation step, the passivation solution is sodium dichromate solution, the temperature of the passivation solution is 42°C, the pH value is 4.5, the concentration is 18g / L, and the charge density of the passivation solution is 170C / m 2 A Cr(OH)3 / Cr2O3 passivation film is formed on the surface of the substrate that has undergone the passivation step, and the mass content ratio of Cr(OH)3 and Cr2O3 in the passivation film is 1.43.

[0032] Example 6 This embodiment provides a method for producing a tin-plated steel sheet, which includes the steps of sequentially performing alkaline cleaning, continuous annealing, planarization, trimming, oiling, and winding of a substrate, and then performing alkaline cleaning, pickling, electroplating, fluxing, reflow, passivation, oiling, and winding of the substrate to obtain a tin-plated steel sheet. The substrate is a low carbon cold rolled hard steel plate with a thickness of 0.25 mm and a width of 920 mm. After normal alkaline cleaning, the substrate is subjected to continuous annealing. The tensile strength of the substrate after annealing is 476 MPa. The flattening step is flattening by double frame, the work roll of the first frame has a surface roughness value of 1.6 μm, a distance in use of 100 km, a rolling force of 5200 kN, the work roll of the second frame has a surface roughness value of 0.52 μm, a distance in use of 75 km, a rolling force of 3300 kN, and a flattening elongation of 1.15%. After flattening, the substrate was detected to have a surface roughness value Ra of 0.5 μm and a peak number Rpc of 65 cm -1 Therefore, the value of 100×Ra+Rpc for the substrate is 115. The width of the board after trimming is 900 mm. The electroplating method in the electroplating step is a methanesulfonic acid electroplating process. During electroplating, the substrate passes through the electroplating tank at a speed of 240 m / min. The temperature of the electroplating solution is 35°C. The concentration of free acid in the electroplating solution is 28 mL / L. 2+The concentration of is 14 mL / L, the single-sided electroplating total current is 7.15 KA, and the cathode current efficiency is 90%. In the passivation step, the passivation solution is sodium dichromate solution, the temperature of the passivation solution is 43°C, the pH value is 4.4, the concentration is 17g / L, and the charge density of the passivation solution is 120C / m 2 A Cr(OH)3 / Cr2O3 passivation film is formed on the surface of the substrate that has undergone the passivation step, and the mass content ratio of Cr(OH)3 and Cr2O3 in the passivation film is 1.

[0033] Example 7 This embodiment provides a method for producing a tin-plated steel sheet, which includes the steps of sequentially performing alkaline cleaning, continuous annealing, planarization, trimming, oiling, and winding of a substrate, and then performing alkaline cleaning, pickling, electroplating, fluxing, reflow, passivation, oiling, and winding of the substrate to obtain a tin-plated steel sheet. The substrate is a low carbon cold rolled hard steel plate with a thickness of 0.35 mm and a width of 908 mm. After normal alkaline cleaning, the substrate is subjected to continuous annealing. The tensile strength of the substrate after annealing is 385 MPa. The flattening step is flattening by double frame, the work roll of the first frame has a surface roughness value of 1.62 μm, a distance in use of 550 km, a rolling force of 5850 kN, the work roll of the second frame has a surface roughness value of 0.54 μm, a distance in use of 50 km, a rolling force of 3200 kN, and a flattening elongation of 1.8%. After flattening, the substrate was detected to have a surface roughness value Ra of 0.55 μm and a peak number Rpc of 71 cm. -1 Therefore, the value of 100×Ra+Rpc for the board is 126. The width of the board after trimming is 888 mm. The electroplating method in the electroplating step is a methanesulfonic acid electroplating process. During electroplating, the substrate passes through the electroplating tank at a speed of 220 m / min. The temperature of the electroplating solution is 55°C. The concentration of free acid in the electroplating solution is 33 mL / L. 2+The concentration of is 16 mL / L, the single-sided electroplating total current is 7.9 KA, and the cathode current efficiency is 83%. In the passivation step, the passivation solution is sodium dichromate solution, the temperature of the passivation solution is 41°C, the pH value is 4.4, the concentration is 16g / L, and the charge density of the passivation solution is 135C / m 2 A Cr(OH)3 / Cr2O3 passivation film is formed on the surface of the substrate that has undergone the passivation step, and the mass content ratio of Cr(OH)3 and Cr2O3 in the passivation film is 1.1.

[0034] Example 8 This embodiment provides a method for producing a tin-plated steel sheet, which includes the steps of sequentially performing alkaline cleaning, continuous annealing, planarization, trimming, oiling, and winding of a substrate, and then performing alkaline cleaning, pickling, electroplating, fluxing, reflow, passivation, oiling, and winding of the substrate to obtain a tin-plated steel sheet. The substrate is a low carbon cold rolled hard steel plate with a thickness of 0.21 mm and a width of 1000 mm. After normal alkaline cleaning, the substrate is subjected to continuous annealing. The tensile strength of the substrate after annealing is 485 MPa. The flattening step is flattening by double frame, the work roll of the first frame has a surface roughness value of 1.68 μm, a distance in use of 500 km, a rolling force of 5700 kN, the work roll of the second frame has a surface roughness value of 0.54 μm, a distance in use of 500 km, a rolling force of 3800 kN, and a flattening elongation of 1%. After flattening, the substrate was detected to have a surface roughness value Ra of 0.56 μm and a peak number Rpc of 74 cm -1 Therefore, the value of 100×Ra+Rpc for the substrate is 130. The width of the board after trimming is 980 mm. The electroplating method in the electroplating step is a methanesulfonic acid electroplating process. During electroplating, the substrate passes through the electroplating tank at a speed of 260 m / min. The temperature of the electroplating solution is 50°C. The concentration of free acid in the electroplating solution is 29 mL / L. 2+The concentration of is 14 mL / L, the single-sided electroplating total current is 8.81 KA, and the cathode current efficiency is 88%. In the passivation step, the passivation solution is sodium dichromate solution, the temperature of the passivation solution is 42°C, the pH value is 4.5, the concentration is 18g / L, and the charge density of the passivation solution is 165C / m 2 A Cr(OH)3 / Cr2O3 passivation film is formed on the surface of the substrate that has undergone the passivation step, and the mass content ratio of Cr(OH)3 and Cr2O3 in the passivation film is 1.36.

[0035] Example 9 This embodiment provides a method for producing a tin-plated steel sheet, which includes the steps of sequentially performing alkaline cleaning, continuous annealing, planarization, trimming, oiling, and winding of a substrate, and then performing alkaline cleaning, pickling, electroplating, fluxing, reflow, passivation, oiling, and winding of the substrate to obtain a tin-plated steel sheet. The substrate is a low carbon cold rolled hard steel plate with a thickness of 0.25 mm and a width of 820 mm. After normal alkaline cleaning, the substrate is subjected to continuous annealing. The tensile strength of the substrate after annealing is 410 MPa. The flattening step is flattening by double frame, the work roll of the first frame has a surface roughness value of 1.63 μm, a distance in use of 25 km, a rolling force of 5050 kN, the work roll of the second frame has a surface roughness value of 0.51 μm, a distance in use of 25 km, a rolling force of 3100 kN, and a flattening elongation of 1.6%. After flattening, the substrate was detected to have a surface roughness value Ra of 0.54 μm and a peak number Rpc of 68 cm -1 Therefore, the value of 100×Ra+Rpc for the substrate is 122. The width of the board after trimming is 800 mm. The electroplating method in the electroplating step is a methanesulfonic acid electroplating process. During electroplating, the substrate passes through the electroplating tank at a speed of 200 m / min. The temperature of the electroplating solution is 38°C. The concentration of free acid in the electroplating solution is 32 mL / L. 2+The concentration of is 15mL / L, the single-sided electroplating total current is 5.3KA, and the cathode current efficiency is 90%. In the passivation step, the passivation solution is sodium dichromate solution, the temperature of the passivation solution is 42°C, the pH value is 4.4, the concentration is 17g / L, and the charge density of the passivation solution is 140C / m 2 A Cr(OH)3 / Cr2O3 passivation film is formed on the surface of the substrate that has undergone the passivation step, and the mass content ratio of Cr(OH)3 and Cr2O3 in the passivation film is 1.25.

[0036] Comparative Example 1 This comparative example provides a method for manufacturing a tin-plated steel sheet. Compared with Example 1, after the planarization step is completed, the surface roughness value Ra of the substrate is 0.52 μm and the number of peaks Rpc is 70 cm -1 , the value of 100×Ra+Rpc is 122, and the charge density of the passivation in the passivation step is 110C / m 2 The difference is that

[0037] Comparative Example 2 This comparative example provides a method for manufacturing a tin-plated steel sheet. Compared with Example 1, after the planarization step is completed, the surface roughness value Ra of the substrate is 0.6 μm and the number of peaks Rpc is 88 cm -1 , the value of 100×Ra+Rpc is 148, and the charge density of the passivation in the passivation step is 185C / m 2 The difference is that

[0038] Comparative Example 3 This comparative example provides a method for producing a tin-plated steel sheet, and is different from Example 1 in that the pH value of the passivation solution in the passivation step is 4.

[0039] Comparative Example 4 This comparative example provides a method for producing a tin-plated steel sheet, and is different from Example 1 in that the concentration of the passivation solution in the passivation step is 20 g / L.

[0040] Comparative Example 5 This comparative example provides a method for producing a tin-plated steel sheet, and is different from Example 1 in that the temperature of the passivation solution in the passivation step is 40°C.

[0041] Comparative Example 6 This comparative example provides a method for producing a tin-plated steel sheet, and is different from Example 1 in that in the flattening step, the surface roughness value Ra of the work roll of the first frame is 1.5 μm.

[0042] Comparative Example 7 This comparative example provides a method for producing a tin-plated steel sheet, and is different from Example 1 in that in the flattening step, the surface roughness value Ra of the work roll of the second frame is 0.3 μm.

[0043] Comparative Example 8 This comparative example provides a method for manufacturing tin-plated steel sheet, and compared with Example 1, the difference is that in the flattening step, the rolling force of the work rolls of the first frame is 6500 kN, and the rolling force of the work rolls of the second frame is 2500 kN.

[0044] Comparative Example 9 This comparative example provides a method for manufacturing a tin-plated steel sheet, and is different from Example 1 in that in the flattening step, the running distance of both the work rolls of the first frame and the work rolls of the second frame is 650 km.

[0045] Comparative Example 10 This comparative example provides a method for producing a tin-plated steel sheet. Compared with Example 1, the electroplating step uses Sn in the electroplating solution. 2+ The difference is that the concentration is 25mL / L.

[0046] Test Example 1 The edge of the tin-plated steel sheet produced in each Example and Comparative Example was cut into a test piece of 120 mm × 120 mm, and a scraper was operated manually or by using a mechanical device to uniformly apply a solvent-based gold paint to the surface of the steel sheet. The thickness of the coating was adjusted according to the model of the scraper, and the coating thickness applied at one time was usually about 6 g / m. 2The coated steel sheet was then placed in an oven heated to 200°C and baked for 15 minutes, after which it was taken out and cooled to room temperature. The coating baking step was repeated once to increase the coating thickness to approximately 12 g / m2. 2 It was decided. The above-mentioned coating test piece was cut into a test piece of 120 mm x 60 mm, placed on the stage of a QFD electric coating adhesion tester, and a scribed circle test was performed, applying an appropriate load so that the needle would scratch the coating, with the length of the circle drawn being 60 to 80 mm and the diameter of the circle being 10 mm. The surface of the test piece on which the circle was drawn was cleaned thoroughly with a brush, 3M610 tape was applied to the entire surface, and the tape was pressed flat with a fingertip to make it adhere to the part on which the circle was drawn. The tape was quickly peeled off upwards, and the condition of the coating on the part of the surface on which the circle was drawn was observed. The degree of damage to the coating in each part was confirmed, and the adhesion was evaluated according to Table 2, with the evaluation results shown in Table 4. According to actual feedback from customers, generally, level 1 is considered to be good adhesion, level 2 is normal adhesion but can be used normally, and levels 3 to 4 is considered to be poor adhesion and cannot be used normally.

[0047] [Table 2]

[0048] Test Example 2 The end of each of the tin-plated steel sheets produced in the Examples and Comparative Examples was cut into a test piece of 50 mm x 50 mm, and the corrosion resistance was tested. The specific test method was as follows. 50 g of citric acid, 0.14 g of sodium nitrate, and 0.5 g of ascorbic acid were dissolved in water, mixed, and diluted to 1000 mL to prepare a test solution. A wire was soldered to the back of the test specimen, and the back and corners of the test specimen were coated with molten beeswax. The test specimen was immersed in the test solution prepared above, and a 15V DC power supply was connected to a stainless steel rod with a diameter of 4 mm and a length of 10 mm as the cathode and the test specimen as the anode, causing anodic corrosion. After 1h, the test specimen was taken out, washed with clean water, and blasted with a hair dryer until the surface was dry. The size and number of corrosion spots were observed, and the corrosion resistance was evaluated according to Table 3. The evaluation results are shown in Table 4.

[0049] [Table 3]

[0050] Test Example 3 The tin-plated steel sheets produced in each Example and Comparative Example were cut into 4 mm x 4 mm test pieces, which were detected and analyzed using XPS, and the composition of the passive film at various depths was tested by argon ion sputtering. The peak division results of the contaminant carbon data were used as a basis to carry out the necessary charge correction for other elements. Peak fitting was performed on the calibrated data using data fitting software, and the mass content ratio of Cr(OH)3 and Cr2O3 was determined based on the peak area ratio. Cr(OH)3 and Cr 2O3 Mass content ratio = mass percentage of Cr(OH)3 in the passive film / mass percentage of Cr2O3 in the passive film.

[0051] [Table 4]

[0052] Obviously, the above examples are merely examples for clear explanation, and do not limit the embodiments. Those skilled in the art may make other different changes or modifications based on the above description. It is not necessary and impossible to comprehensively cover all the embodiments here. And, obvious changes or modifications derived therefrom still fall within the scope of protection of the present invention.

Claims

1. A method for producing a tin-plated steel sheet, comprising the steps of: In the step of planarizing the substrate, a double frame planarization is adopted, the distance between the work roll of the first frame and the work roll of the second frame during use is not more than 600 km, the work roll of the first frame has a surface roughness value Ra of 1.6 to 1.7 μm and a rolling force of 5000 to 6000 kN, and the work roll of the second frame has a surface roughness value Ra of 0.5 to 0.6 μm and a rolling force of 3000 to 4000 kN; In the step of electroplating the substrate, the electroplating solution is 2+ The concentration is 14 to 19 mL / L, In the step of passivating the substrate, the passivation solution has a temperature of 41-43° C., a pH value of 4.4-4.6, a concentration of 16-18 g / L, and a charge density of 120-180 C / m 2 and 120 C / m when the surface roughness value Ra and the number of peaks Rpc of the substrate satisfy 115≦100×Ra+Rpc<130 2 ≦ Passivation charge density < 150 C / m 2 and 150 C / m when the surface roughness value Ra and the number of peaks Rpc of the substrate satisfy 130≦100×Ra+Rpc≦155 2 ≦Passivation charge density≦180 C / m 2 The method according to claim 1,

2. The method for producing a tin-plated steel sheet according to claim 1, characterized in that the flattening elongation in the flattening step is 1 to 1.8%.

3. In the planarization step, When the distance during use of the work rolls of the first frame is 50 km or less, the rolling force of the work rolls of the first frame is 5000 kN≦5100 kN; In the case where 50 km<the distance when the work roll of the first frame is used≦100 km, 5100 kN<the rolling force of the work roll of the first frame≦5200 kN, In the case where 100 km<the distance when the work roll of the first frame is used≦500 km, 5200 kN<the rolling force of the work roll of the first frame≦5700 kN, 2. The method for producing a tin-plated steel sheet according to claim 1, wherein, in the case where 500 km<distance during use of the work rolls of the first frame≦600 km, 5700 kN<rolling force of the work rolls of the first frame≦6000 kN.

4. In the planarization step, When the distance during use of the work rolls of the second frame is 50 km or less, the rolling force of the work rolls of the second frame is 3000 kN≦3200 kN; In the case where 50 km<the distance when the work roll of the second frame is used≦100 km, 3200 kN<the rolling force of the work roll of the second frame≦3400 kN, In the case where 100 km<the distance when the work roll of the second frame is used≦500 km, 3400 kN<the rolling force of the work roll of the second frame≦3800 kN, 2. The method for producing a tin-plated steel sheet according to claim 1, wherein, when 500 km<distance during use of the work rolls of the second frame≦600 km, the rolling force of the work rolls of the second frame is 3800 kN<≦4000 kN.

5. After the planarization step is completed, the substrate has a surface roughness value Ra of 0.5 to 0.6 μm and a peak count Rpc of 65 to 95 cm -1 The method for producing a tin-plated steel sheet according to claim 1,

6. 2. The method for producing a tin-plated steel sheet according to claim 1, wherein in the electroplating step, the electroplating manner is a methanesulfonic acid electroplating process, and during electroplating, the substrate passes through the electroplating tank at a speed of 200 to 300 m / min.

7. The method for producing a tin-plated steel sheet according to claim 1, wherein in the electroplating step, the temperature of the electroplating solution is 35 to 55°C.

8. In the electroplating step, the concentration of free acid in the electroplating solution is 28 to 38 mL / L; And / or, the one-sided electroplating total current is 5.3-11.6 KA, and the cathode current efficiency is 80-90%.

9. The surface of the substrate that has undergone the passivation step is treated with Cr(OH) 3 / Cr 2 O 3 A passivation film is formed, Cr(OH) in the passivation film 3 and Cr 2 O 3 The method for producing a tin-plated steel sheet according to claim 1, characterized in that the mass content ratio of

10. 2. The method for producing tin-plated steel sheet according to claim 1, further comprising a continuous annealing step before planarizing, wherein the substrate subjected to the continuous annealing step has a tensile strength of 385-485 MPa.

11. The method for producing a tin-plated steel sheet according to any one of claims 1 to 10, characterized in that the passivation solution is a sodium dichromate solution.

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