Wide ultrathin tinplate and preparation method thereof

Abstract

The invention relates to a wide ultra-thin specification tinplate and a preparation method thereof. A tinplate base material comprises the following chemical components: 0.0010%-0.0014% of C, less than or equal to 0.02% of Si, 0.09%-0.14% of Mn, less than or equal to 0.015% of P, less than or equal to 0.004% of S, 0.0146%-0.0158% of N, 0.0038%-0.0049% of B, 0.015%-0.045% of Alt, 0.0012%-0.0024% of Mg and 0.077%-0.094% of Ti. And the balance of Fe and impurities. The produced wide and ultra-thin tinplate (the thickness is 0.08-0.18 mm, and the width is larger than or equal to 2000 mm) has good structure and performance uniformity, and the alloy cost of the tinplate base material is low; and meanwhile, the problems of quality defects such as strip breakage, holes and bright strips in the cold rolling annealing process of a conventional production process are solved.

Description

Technical Field

[0001] The invention relates to the technical field of tinplate production, in particular to wide-width and ultra-thin tinplate and a preparation method thereof. Background Art

[0002] Tinplate (tinplate) is cold-rolled low-carbon steel sheet and strip coated with pure tin on both sides. As a high-value-added cold-rolled coated steel, it features corrosion resistance, non-toxicity, high strength, and excellent ductility. It is widely used in industries such as canning, packaging, and stamping containers. Tinplate can be divided into five types, MRT1 to MRT5, based on the tempering grade, and CA and BA, based on the annealing process. Finished tinplate thickness generally ranges from 0.20 to 0.5 mm, while thin-gauge tinplate (thickness ≤ 0.19 mm) is mostly imported.

[0003] With the development of lightweight application technologies, demand for thin-gauge tinplate materials is growing rapidly. The thickness of the hot-rolled base material used in thin-gauge tinplate generally ranges from 1.8 to 2.48 mm, with cold-rolling reductions exceeding 90%. The cold-rolling process typically utilizes single-stand rolling or continuous rolling mills. The continuous annealing (CA) process is more suitable for stamping than the bell annealing (BA) process due to its advantages such as uniform annealing temperature, high production efficiency, and high yield rate.

[0004] The steel composition system for tinplate using the continuous annealing process includes: (1) adding a certain amount of microalloying elements to the composition of low-carbon aluminum-killed steel; (2) adding a certain amount of niobium, vanadium and aluminum to the composition of ultra-deep drawing interstitial-free steel (IF steel) to improve the strength, but the alloy cost is high.

[0005] Currently, the following problems exist in the production of extremely thin tinplate (0.08-0.18mm): 1) The high alloy cost due to the large amount of alloying elements added (such as V, Nb and Al); 2) The finished product structure and performance are uneven; 3) The addition of nitrogen can easily cause the molten steel surface to churn; 4) Quality defects such as broken strips, holes, and bright strips are prone to occur during cold rolling and annealing.

[0006] Chinese patent application publication number CN119406934A discloses a "wide tinplate steel strip and its preparation method." The invention relates to a continuous casting slab that is heat-treated and then hot-rolled to produce an initial steel strip. The rough rolling process involves a reduction ratio of at least 75% of the total slab reduction. The rough rolling process involves six rough rolling passes and seven finishing passes, with the first three rough rolling passes achieving a reduction ratio of at least 17%, the last three rough rolling passes achieving a reduction ratio of at least 27%, and the first four finishing passes achieving a reduction ratio of at least 30%. The initial steel strip is laminar-cooled to a coiling temperature and then coiled to produce a wide tinplate steel strip. The preparation method primarily addresses the distribution of reduction ratios for hot-rolling, roughing, and finishing, as well as the laminar cooling rate and coiling temperature. The invention does not address the chemical composition of the steel or the cold rolling annealing process. Furthermore, the width of the wide tinplate is not specifically specified.

[0007] Chinese patent application publication number CN118638995A discloses a "method for preparing tinplate." The composition and weight percentages of the tinplate are as follows: C 0.033-0.048%, Mn 0.18-0.30%, Si ≤ 0.02%, Als 0.02-0.05%, N ≤ 0.0040%, P ≤ 0.015%, S ≤ 0.012%, with the remainder being Fe and unavoidable impurities. The tinplate has an HR30T hardness of 54-60. The preparation method includes: heating the cast slab, hot rolling it, and controlling the final rolling temperature so that the heated continuous cast slab is rolled in the austenite / ferrite two-phase region; coiling the hot-rolled sheet at a controlled coiling temperature, followed by pickling and cold rolling to obtain a chilled coil; continuously annealing the chilled coil at a controlled annealing temperature to achieve complete microstructure recrystallization, and then tinning it to obtain the tinplate. It focuses on hot rolling, cold rolling continuous annealing, and tinning processes, but does not mention the performance and use of the product. It is a conventional tinplate preparation method.

[0008] The Chinese invention patent with authorization announcement number CN1174109C discloses an "ultra-thin steel strip for battery shells and its manufacturing method." Ultra-low carbon Ti-Nb-IF steel is used to produce battery shell steel. The process flow includes molten iron pre-desulfurization, converter smelting, refining outside the furnace (RH treatment), continuous casting, hot rolling, coiling, pickling, cold rolling, continuous annealing, slitting and oil coating packaging. To achieve an interstitial-free (IF) state, Ti and Nb are added in combination to fix the C and N interstitial atoms, so that C and Nb combine to form NbC, and N and Ti combine to form TiN. The Al in the steel participates in the fixation of the N interstitial atoms. The steel contains a large amount of Ti alloy, the production process is difficult to control, and the production cost is high; the finished product has a large planar anisotropy (Δr value), and the excess Ti and Nb content is too high, which will have an adverse effect on the deep drawing performance of the finished steel plate. In addition, it has no leveling process and cannot eliminate or reduce the slight surface defects caused by the previous process. It is difficult to achieve the plate shape and roughness required by users, and it is difficult to improve the adhesion of the battery shell coating. Summary of the Invention

[0009] The present invention provides wide-width and ultra-thin tinplate and a preparation method thereof. The produced wide-width and ultra-thin tinplate (thickness 0.08-0.18 mm, width ≥ 2000 mm) has good uniformity of structure and performance, and the alloy cost of the tinplate substrate is low. At the same time, the problem of quality defects such as broken strips, holes, and bright strips that are easily generated during the cold rolling annealing process in conventional production processes is solved.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] Disclosed is a wide and ultra-thin tinplate. The chemical composition of the tinplate base material is, by mass percentage, as follows: C: 0.0010%-0.0014%, Si≤0.02%, Mn: 0.09%-0.14%, P≤0.015%, 0.002%≤S≤0.004%, N: 0.0146%-0.0158%, B: 0.0038%-0.0049%, Alt: 0.015%-0.045%, Mg: 0.0012%-0.0024%, Ti: 0.077%-0.094%; and 0.24≤B / N≤0.34, 0.3≤Mg / S≤1.2; the remainder is Fe and unavoidable impurities, and the inclusion size is ≤20µm.

[0012] The controlled elements in the chemical composition of the tinplate substrate include: Cu≤0.02%, Ni≤0.01%, Mo≤0.01%, Nb≤0.004%, As≤0.01%, Cr+Pb≤0.005wt%, and the total amount of the controlled elements shall not exceed 0.10%.

[0013] The properties of tinplate products are: yield strength 264~284MPa, tensile strength 362~382MPa, elongation after fracture A 80 ≥40%, r 90 ≥1.8, ≤0.2, inclusion size ≤20µm.

[0014] The thickness of the finished tinplate product is 0.08~0.18mm and the width is ≥2000mm.

[0015] A method for preparing wide and ultra-thin tinplate comprises the following steps:

[0016] 1) Converter smelting: Combined-blowing converter smelting is adopted, with bottom blowing of nitrogen throughout the smelting process; lime and light-burned dolomite are used for slag formation, with an oxygen blowing time of 17-20 minutes. Before tapping, the carbon content in the molten steel is controlled to be ≤0.05%, the oxygen content is ≤500ppm, and the slag thickness is ≤50mm; the tapping temperature is controlled at 1772-1792°C, the tapping time is controlled to be 4-7 minutes, and a slide plate is used to block the slag during tapping;

[0017] 2) RH vacuum treatment: Nitrogen is used as the lifting gas to feed wire and increase nitrogen in the molten steel after RH vacuum treatment. The RH net cycle time is 10-14 minutes, and the calming time after RH treatment is 15-20 minutes. Then, manganese nitride cored wire and magnesium alloy cored wire are fed into the molten steel. The feeding rate of manganese nitride cored wire is 4.0-4.3m / t steel, and the feeding speed is 3.1-3.5m / s. The feeding speed of magnesium alloy cored wire is 25-30m / min, and the feeding rate is 0.3-0.5kg / t steel. The ladle bottom blowing is turned off during the wire feeding process.

[0018] 3) Continuous casting: Use straight arc continuous casting machine for continuous casting, and control the superheat at 36-44℃;

[0019] 4) Hot rolling:

[0020] Heating: The continuous casting billet adopts hot delivery and hot charging process, and the heating temperature is 1262~1282℃;

[0021] Rough rolling: adopt 3+5 rolling mode, and the starting temperature of rough rolling is 1116~1138℃;

[0022] Finishing rolling: adopt 7-stand hot continuous rolling, cooling water is added between stands, and the final rolling temperature is 890-920℃;

[0023] Coiling: adopts a segmented cooling process. The first stage of cooling is to open two sets of cooling water immediately after the steel plate leaves the F7 rack for cooling. After air cooling for 2 to 3 seconds, laminar cooling water is opened again for cooling. The coiling temperature is 570 to 600 ° C.

[0024] Slow cooling: After coiling, the steel plate enters the slow cooling pit for slow cooling treatment for more than 36 hours.

[0025] 5) Pickling: Use push-pull pickling unit with a pickling speed of 152-164m / min;

[0026] 6) Cold rolling: Using a six-roll reversible rolling mill, hot rolled coils with a thickness of 1.8 to 2.48 mm are used. After multiple passes of rolling, finished steel plates with a thickness of 0.08 to 0.18 mm are obtained;

[0027] 7) Continuous annealing: A continuous annealing unit with ROA function is used to carry out annealing in the soaking section, rapid cooling section, secondary heating section and aging section in sequence. The soaking section has a soaking temperature of 724-751°C, the rapid cooling section cools the temperature to 262-282°C at a cooling rate of 36-40°C / s, the secondary heating section heats to 425-445°C, and the aging section cools to 10-32°C at a cooling rate of 8.5-9.5°C / s. The steel is then cooled in a quenching tank and dried in a drying oven before being discharged from the furnace.

[0028] 8) Flatness: Flatness elongation is controlled at 1.52% to 1.84%;

[0029] 9) Tin plating: Using insoluble anode tin plating production line, double-sided tin plating amount is 2.5~3.5 / 2.5~3.5g / m 2 , the tinning speed is 306~326m / min.

[0030] In the step 1), during converter smelting, the weight percentage of molten iron is 51% to 58%, and the weight percentage of scrap steel is 42% to 49%.

[0031] In the step 2), the manganese nitride cored wire contains N: 12% to 15%, Mn: 83% to 84% by mass, and the rest are impurities.

[0032] In the step 3), the fixed length of the continuous casting billet is 10.5 m.

[0033] In step 5), four hydrochloric acid pickling tanks are provided, and the mass concentrations of HCl in pickling tanks 1# to 4# are 5.2% to 7.2%, 10.2% to 13.4%, 15.4% to 17.2%, and 13.6% to 15.8%, respectively.

[0034] In the step 8), a double-stand six-roller leveling machine is used for leveling.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1) The alloy cost of the tinplate substrate is low, which is conducive to market promotion. The present invention adds B, Ti, and N as strengthening elements to ultra-low carbon-manganese steel, controls 0.24≤B / N≤0.34, 0.026≤Mg / Alt≤0.16, and adds Mg to control the appearance and size of inclusions, thereby obtaining a wide and ultra-thin tinplate substrate with excellent comprehensive performance.

[0037] 2) During converter smelting, scrap steel accounts for 42% to 49%, which means that the green steel smelting process is used, resulting in pure steel quality. By limiting the scrap steel ratio, carbon dioxide emissions during the tinplate production process can be reduced.

[0038] 3) In order to achieve reasonable nitrogen content requirements and avoid churning of the molten steel surface caused by the addition of nitrogen, the present invention adopts a wire feeding process to ensure that the manganese nitride cored wire enters the molten steel to a sufficient depth; during wire feeding, argon blowing from the bottom of the ladle is turned off to reduce the flow force of the molten steel, effectively weaken the slag-metal reaction and the molten steel-air reaction, and avoid deterioration of the cleanliness of the molten steel;

[0039] 4) The use of consistent production technology and the small C40 crown of the steel strip during hot rolling can prevent the steel strip from deviating during cold rolling, thereby reducing the risk of cold-rolled strip breakage, holes, and bright strips;

[0040] 5) The properties of tinplate finished products are: yield strength 264~284MPa, tensile strength 362~382MPa, elongation after fracture A 80 ≥40%, r 90 ≥1.8, ≤0.2, inclusion size ≤20µm; among which, is the absolute value of Δr, the anisotropic difference of Δr plastic strain ratio, Δr=(r0-2r 45 +r 90 ) / 2; r0, r 45 and r 90 These are the Lankford values ​​at 0°, 45°, and 90° relative to the rolling direction of the steel plate.

[0041] 6) The finished tinplate has good corrosion resistance, certain strength and hardness, good formability and is easy to weld; the final tinplate (tinplate) is non-toxic and odorless, can prevent iron from dissolving into the packaged material, and has a bright surface; the finished tinplate has good processing performance, good comprehensive protection performance, and good product structure and performance uniformity;

[0042] 7) After hot rolling, rapid cooling (cooling rate ≥ 10℃ / s) and a lower coiling temperature (570-600℃) are used, so that the AlN particles do not have time to precipitate during the cooling process, and remain in a solid solution state in the hot-rolled steel strip, and only precipitate finely on the subgrain boundaries, which is conducive to obtaining larger and uniform cake-shaped grains, avoiding the occurrence of mixed crystals with uneven grains, and is beneficial to improving the stamping performance of tinplate. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a metallographic photograph of the tinplate substrate prepared in Example 1 of the present invention.

[0044] Figure 2 This is the inclusion morphology of the tinplate substrate prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0045] In the wide and ultra-thin tinplate of the present invention, the chemical composition of the tinplate base material is, by mass percentage, C: 0.0010% to 0.0014%, Si≤0.02%, Mn: 0.09% to 0.14%, P≤0.015%, 0.002%≤S≤0.004%, N: 0.0146% to 0.0158%, B: 0.0038% to 0.0049%, Alt: 0.015% to 0.045%, Mg: 0.0012% to 0.0024%, and Ti: 0.077% to 0.094%; and 0.24≤B / N≤0.34, 0.3≤Mg / S≤1.2; the remainder is Fe and unavoidable impurities, and the inclusion size is ≤20µm.

[0046] In order to achieve the purpose of pure steel smelting, the elements not intentionally added to the tinplate substrate of the present invention, namely the controlled elements, include: Cu≤0.02%, Ni≤0.01%, Mo≤0.01%, Nb≤0.004%, As≤0.01%, Cr+Pb≤0.005wt%, and the total amount of the controlled elements does not exceed 0.10%.

[0047] The working principle of each chemical element in the tinplate substrate of the present invention is as follows:

[0048] C: In the tinplate substrate, the ultra-low C content combines with the N and Ti in the steel to form ultra-deep-drawing interstitial-free atomic steel. Nano-sized Ti (C, N) is beneficial for improving the deep-drawing and forming properties of wide and ultra-thin tinplate substrates. The present invention controls the C content to 0.0010% to 0.0014%.

[0049] Si: For tinplate substrates, tin plating treatment is required after cold rolling. Low silicon content is beneficial to the adhesion performance of the coating. In addition, low Si content is also beneficial to improving the surface quality of the steel plate. Therefore, the present invention controls the Si content to ≤0.02%.

[0050] Mn: It is a commonly used solid solution strengthening element in steel. In order to ensure the structure and performance of the tinplate substrate, the present invention controls the Mn content to 0.09% to 0.14%.

[0051] P: is a harmful element in steel. It will aggregate and grow at the grain boundaries, which will reduce the toughness and formability of the tinplate substrate and cause cold brittleness. Therefore, the present invention controls the P content to be ≤0.015%.

[0052] S: is a harmful element in steel and will generate MnS inclusions in the steel. The lower its content, the better. Therefore, the present invention controls the S content to be ≤0.0004%.

[0053] Ti: It fixes carbon and nitrogen in ultra-low carbon steel. Ti is relatively active and can contribute to precipitation strengthening. It generates TiN, TiC, and Ti(C, N) particles, with TiN forming first, followed by TiC and Ti(C, N), contributing to the steel's strength and toughness. Furthermore, Ti improves the cupping and hole expansion properties of the tinplate substrate, thereby enhancing deep-drawing performance. In this invention, the Ti content is controlled to 0.077% to 0.094%.

[0054] Mg: Its main function is to modify inclusions and play a role in oxide metallurgy. It improves the comprehensive performance of the tinplate substrate by forming spherical and point-shaped Mn-SOBN-Mg composite compounds. The present invention controls the Mg content to 0.0012% to 0.0024%, and at the same time, controls 0.3≤Mg / S≤1.2.

[0055] N: A certain amount of N combines with Ti, B, and C to form Ti(C, N), BN, and other elements, which play a role in precipitation strengthening and grain refinement in steel. Its main functions in tinplate substrates include: first, increasing the proportion of dissolved N in the total N content, effectively promoting N solid solution in the steel; second, increasing the absolute content of dissolved N and combined N in the steel; and third, increasing the N content in BN and AlN precipitated phases in the steel, as well as increasing the proportion of N in these BN and AlN precipitated phases in the total N content, promoting the precipitation of combined N in the steel as BN and AlN phases. Through precipitation strengthening, stable control of the properties of low-cost, high-purity tinplate is achieved. The present invention controls the N content to 0.0146% to 0.0158%.

[0056] B: In the tinplate matrix, B combines with N to form BN particles. BN has good stability and contributes to uniform microstructure and performance. Furthermore, B segregates at austenite grain boundaries, inhibiting the precipitation of proeutectoid ferrite and allowing carbides to disperse and precipitate in the low-temperature range. The present invention controls the B content to 0.0038% to 0.0049%.

[0057] Alt: Reacts with nitrogen to form AlN, which hinders grain growth and refines grains. When combined with specific processes, it can effectively improve the strength and toughness of the tinplate substrate. In the present invention, the Alt content is controlled within the range of 0.015% to 0.045%.

[0058] It should be noted that obtaining high-performance tinplate substrates is not only related to chemical composition design, but also to production technology. Only through reasonable composition design combined with optimized production technology can the desired microstructure be achieved, thereby effectively improving the deep drawing performance, formability, and corrosion resistance of the tinplate substrate.

[0059] The present invention adopts a consistent technology to produce wide and ultra-thin tinplate, and the specific steps are as follows:

[0060] 1. Converter Smelting: The converter utilizes a combined-blowing converter (BOF) with a weight ratio of molten iron to scrap steel of 51%-58%:42%-49%. Nitrogen is blown from the bottom throughout the smelting process, and lime and light-burned dolomite are used for slag formation. The oxygen blowing time is 17-20 minutes, and the smelting endpoint is controlled to [C] ≤ 0.05%, [O] ≤ 500 ppm, and the slag thickness ≤ 50 mm. Controlling the converter atmosphere allows for precise control of the nitrogen content at the converter endpoint, thereby enabling precise control of the nitrogen content in the finished product. Tapping begins when the final composition and temperature meet the tapping requirements. The tapping port is kept circular, and the tapping time is controlled to 4-7 minutes. Slide plates are used to prevent slag, ensuring a single slag stop during tapping and mandatory slag removal during the later stages of tapping. The tapping temperature is controlled between 1772°C and 1792°C.

[0061] 2. RH Vacuum Treatment: A deep decarburization treatment is performed using nitrogen as the lifting gas. Wire feeding and nitrogen enrichment are then added to the molten steel after the RH vacuum treatment. Magnesium alloy cored wire is then added. The RH cycle time is 10-14 minutes, and the post-RH treatment calming time is 15-20 minutes. Manganese nitride cored wire is fed into the molten steel via a wire feeder at a feed rate of 4.0-4.3 m / t of steel and a wire feeding speed of 3.1-3.5 m / s. Bottom blowing is disabled during the feeding process. The nitrogen content of the manganese nitride cored wire is 12-15% by weight, and the manganese content is 83-84% by weight, with the remainder being impurities. The magnesium alloy cored wire is fed at a speed of 25-30 m / min and a feed rate of 0.3-0.5 kg / t of steel. The unique cored wire design and feeding process improve nitrogen recovery, while suppressing the slag-metal reaction rate during the wire feeding process and reducing the buildup of inclusions.

[0062] 3. Continuous casting: Use a straight arc continuous casting machine for continuous casting, control the superheat between 36 and 44°C, and the fixed length of the continuous casting billet is preferably 10.5m.

[0063] 4. Hot rolling, details are as follows:

[0064] Heating: Continuous casting is processed using a hot delivery and hot charging process, with a heating temperature of 1262-1282°C to fully dissolve the alloying elements in the steel. By limiting the heating temperature, the plasticity of the continuous casting can be improved, deformation resistance can be reduced, and the temperature inside and outside the continuous casting can be uniform, which is conducive to processing and forming. At the same time, the internal structure of the continuous casting can be improved and increased burn-in of the continuous casting can be avoided. If the heating temperature is too high, the degree of oxidation on the continuous casting surface will increase; if the heating temperature is too low, the thermoplasticity of the continuous casting can be reduced, resulting in surface defects.

[0065] Rough rolling: adopt 3+5 rolling mode, and the starting temperature of rough rolling is 1116~1138℃;

[0066] Finishing rolling: adopt 7-stand hot continuous rolling, cooling water is added between stands, and the final rolling temperature is 890-920℃;

[0067] Coiling: A segmented cooling process is adopted. The first stage of cooling is to start two sets of water cooling immediately after the steel plate leaves the F7 rack, followed by air cooling for 2 seconds, and then laminar cooling water cooling; the coiling temperature is 570-600℃, in order to ensure the uniformity of structure and performance.

[0068] Slow cooling: The steel plate after coiling enters the slow cooling pit for slow cooling treatment and can be moved after 36 hours.

[0069] 5. Pickling: Use a push-pull pickling unit for pickling. To ensure the pickling quality, the pickling speed is controlled at 152-164 m / min. Preferably, four hydrochloric acid pickling tanks are provided, and the mass concentrations of HCl in the 1# to 4# pickling tanks are 5.2%-7.2%, 10.2%-13.4%, 15.4%-17.2%, and 13.6%-15.8%, respectively.

[0070] 6. Cold rolling: It is rolled on a six-roll reversible rolling mill, using hot-rolled coils with a thickness of 1.8 to 2.48 mm. After multiple passes of rolling, cold-rolled plates with a thickness of 0.08 to 0.18 mm are obtained.

[0071] 7. Continuous annealing: A continuous annealing unit with ROA function (including soaking section, rapid cooling section, secondary heating section and aging section) is used. The soaking temperature of the soaking section is 724-751°C, the rapid cooling section is cooled to 262-282°C at a cooling rate of 36-40°C / s, the secondary heating section is heated to 425-445°C, and the aging section is cooled to 10-32°C at a cooling rate of 8.5-9.5°C / s. The steel is cooled in a quenching tank and dried in a drying oven before being taken out of the furnace.

[0072] The present invention utilizes a ROA annealing process, rapidly cooling the high-temperature steel strip to between 262°C and 282°C via rapid cooling at a rate of 36°C / s to 40°C / s. This causes lattice distortion in the ferrite lattice, thereby facilitating the nucleation of Fe3C within the ferrite grains. Once carbon reaches supersaturation, the growth of Fe3C nucleation depends primarily on thermal diffusion (higher temperatures lead to faster diffusion). A secondary heating process is then performed to an overaging temperature of 425°C to 445°C to facilitate the rapid precipitation of carbon from the supersaturated solid solution, thereby improving the product's aging resistance and stamping performance. Furthermore, at the same temperature, as the carbon supersaturation in the ferrite decreases, it eventually approaches its equilibrium concentration. Maintaining a cooling rate of 8.5°C / s to 9.5°C / s during the aging process reduces the carbon saturation with decreasing temperature, lowering the final residual solid solution carbon content. This weakens the pinning effect of the solid solution carbon on dislocations, thereby improving the product's aging resistance and stamping performance.

[0073] 8. Leveling: The leveling process uses a double-stand six-roller leveling machine for leveling, and the leveling elongation is controlled at 1.52% to 1.84%.

[0074] 9. Tin plating: Tin plating adopts insoluble anode tin plating production line, and the double-sided tin plating amount is 2.5~3.5 / 2.5~3.5g / m 2 , the tinning speed is 306~326m / min.

[0075] The method for preparing wide-width, ultra-thin tinplate of the present invention is to heat and hot-roll the continuous casting billet, and control the final rolling temperature of the hot rolling to 890°C to 920°C, so that the heated continuous casting billet is rolled in the austenite / ferrite two-phase region, while improving the structural distortion energy and the recrystallization driving force of the heated continuous casting billet. The hot-rolled plate is cooled in sections and the coiling temperature is controlled to reduce the structural recrystallization of the hot-rolled plate to achieve the effect of grain refinement. The hot-rolled plate is then pickled and cold-rolled. Pickling can remove the iron oxide scale on the surface of the hot-rolled plate, so that the hot-rolled plate presents a better surface state, which is convenient for controlling the plate shape and mechanical properties in the subsequent cold rolling process, and greatly improves the recrystallization driving force of the hot-rolled plate after pickling during the cold rolling process to obtain a chilled coil. The chilled coils are continuously annealed, and the annealing temperature is controlled. While ensuring the finished product's grain size, microstructure, and mechanical properties, the continuous annealing process is rationally designed. This effectively improves continuous annealing efficiency and reduces fuel consumption, resulting in a tinplate substrate with excellent deep-drawing, drawing, and corrosion resistance. After the tinplate substrate is flattened and tinned, the resulting tinplate is the finished product.

[0076] The tinplate product produced by the present invention has a thickness of 0.08-0.18 mm and a width of ≥2000 mm. The tinplate product performance is: yield strength 264-284 MPa, tensile strength 362-382 MPa, elongation after fracture A80 ≥40%, r 90 ≥1.8, ≤0.2, inclusion size ≤20µm.

[0077] The tinplate produced by the invention can be used to make two-piece cans and DR materials, and has beautiful appearance and excellent corrosion resistance.

[0078] In order to more intuitively embody the present invention, the embodiments of the present invention are further described in conjunction with examples. The following examples are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solution that can be obviously obtained by a person skilled in the art within the technical scope disclosed in the present invention, including simple changes or equivalent replacements, is within the scope of protection of the present invention.

[0079] Example:

[0080] In this embodiment, the production process of wide and ultra-thin tinplate is as follows:

[0081] 1. Molten steel smelting: Weigh each component raw material according to the formula ratio, and then smelt to obtain molten steel. The chemical composition of the molten steel in each embodiment is shown in Table 1.

[0082] Table 1

[0083]

[0084] 2. Refining and continuous casting: The molten steel is smelted in a top-bottom combined-blowing converter, subjected to RH vacuum treatment, and continuously cast to prepare a continuous casting billet. The steelmaking and continuous casting process parameters of each embodiment are shown in Table 2.

[0085] Table 2

[0086]

[0087] 3. Hot Rolling: Continuously cast slabs were produced using a hot delivery and hot charging process. Roughing was performed using a 3+5 rolling pattern, and finishing was performed using a 7-stand hot rolling process with cooling water added between stands. Laminar cooling was performed using a staged cooling process. The coiling temperature was 570-600°C. After coiling, the steel plates were subjected to a slow cooling pit for 36 hours before being allowed to be moved. The hot rolling process parameters for each example are shown in Table 3.

[0088] Table 3

[0089]

[0090] 4. Pickling, cold rolling, continuous annealing, tempering and tinning: Pickling is carried out using a push-pull pickling unit and rolling is carried out using a six-roll reversible rolling mill. Hot-rolled coils with a thickness of 1.8 to 2.48 mm are rolled through multiple passes to obtain cold-rolled steel sheets with a thickness of 0.08 to 0.18 mm. Continuous annealing is carried out using a continuous annealing unit with ROA function, and the tempering process is carried out using a double-stand six-roll tempering mill. Tinning is carried out using an insoluble anode tinning production line with a tinning amount of 3.0 / 3.0 g / m 2 , the tinning speed is 306-326 m / min, and the process parameters of pickling-tinning in each embodiment are shown in Table 4.

[0091] Table 4

[0092]

[0093] The tinplate product obtained in this embodiment has a thickness of 0.08-0.18 mm and a tin plating amount of 3.0 / 3.0 g / m 2 .

[0094] Figure 1 This is a metallographic photograph of the tinplate substrate prepared in Example 1. The microstructure is ferrite + cementite (trace), and the grain size is level 13. Figure 2 This is the inclusion morphology of the tinplate substrate prepared in Example 1. The inclusion size is 8.7 μm.

[0095] The properties of the tinplate product obtained in this embodiment are: yield strength 264-284 MPa, tensile strength 362-382 MPa, elongation after fracture A 80 ≥40%, r 90 ≥1.8, ≤0.2, inclusion size ≤20µm. The product properties of each embodiment are shown in Table 5.

[0096] Table 5

[0097]

[0098] Conclusion: Through reasonable chemical composition design and hot rolling controlled rolling and controlled cooling, cold rolling annealing and tin plating process, this example obtains wide and ultra-thin tinplate products (0.08-0.18 mm × 2000 mm). The product has excellent performance and can completely replace imported products to meet the market demand of the canning industry and stamping containers.

[0099] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A wide and ultra-thin tinplate, characterized in that: The chemical composition of the tinplate base material is as follows by mass percentage: C: 0.0010%~0.0014%, Si≤0.02%, Mn: 0.09%~0.14%, P≤0.015%, 0.002%≤S≤0.004%, N: 0.0146%~0.0158%, B: 0.0038%~0.0049%, Alt: 0.015%~0.045%, Mg: 0.0012%~0.0024%, Ti: 0.077%~0.094%; and 0.24≤B / N≤0.34, 0.3≤Mg / S≤1.2; the rest is Fe and unavoidable impurities, and the inclusion size is ≤20µm.

2. The wide and ultra-thin tinplate according to claim 1, characterized in that: The controlled elements in the chemical composition of the tinplate substrate include: Cu≤0.02%, Ni≤0.01%, Mo≤0.01%, Nb≤0.004%, As≤0.01%, Cr+Pb≤0.005wt%, and the total amount of the controlled elements shall not exceed 0.10%.

3. The wide and ultra-thin tinplate according to claim 1, characterized in that: The properties of tinplate products are: yield strength 264~284MPa, tensile strength 362~382MPa, elongation after fracture A 80 ≥40%, r 90 ≥1.8, ≤0.2, inclusion size ≤20µm.

4. The wide and ultra-thin tinplate according to claim 1, characterized in that: The thickness of the finished tinplate product is 0.08~0.18mm and the width is ≥2000mm.

5. A method for preparing wide-width and ultra-thin tinplate according to any one of claims 1 to 4, characterized in that: The steps include: 1) Converter smelting: Combined-blowing converter smelting is adopted, with bottom blowing of nitrogen throughout the smelting process; lime and light-burned dolomite are used for slag formation, with an oxygen blowing time of 17-20 minutes. Before tapping, the carbon content in the molten steel is controlled to be ≤0.05%, the oxygen content is ≤500ppm, and the slag thickness is ≤50mm; the tapping temperature is controlled at 1772-1792°C, the tapping time is controlled to be 4-7 minutes, and a slide plate is used to block the slag during tapping; 2) RH vacuum treatment: Nitrogen is used as the lifting gas to feed wire and increase nitrogen in the molten steel after RH vacuum treatment. The RH net cycle time is 10-14 minutes, and the calming time after RH treatment is 15-20 minutes. Then, manganese nitride cored wire and magnesium alloy cored wire are fed into the molten steel. The feeding rate of manganese nitride cored wire is 4.0-4.3m / t steel, and the feeding speed is 3.1-3.5m / s. The feeding speed of magnesium alloy cored wire is 25-30m / min, and the feeding rate is 0.3-0.5kg / t steel. The ladle bottom blowing is turned off during the wire feeding process. 3) Continuous casting: Use straight arc continuous casting machine for continuous casting, and control the superheat at 36-44℃; 4) Hot rolling: Heating: The continuous casting billet adopts hot delivery and hot charging process, and the heating temperature is 1262~1282℃; Rough rolling: adopt 3+5 rolling mode, and the starting temperature of rough rolling is 1116~1138℃; Finishing rolling: adopt 7-stand hot continuous rolling, cooling water is added between stands, and the final rolling temperature is 890-920℃; Coiling: adopts a segmented cooling process. The first stage of cooling is to open two sets of cooling water immediately after the steel plate leaves the F7 rack for cooling. After air cooling for 2 to 3 seconds, laminar cooling water is opened again for cooling. The coiling temperature is 570 to 600 ° C. Slow cooling: After coiling, the steel plate enters the slow cooling pit for slow cooling treatment for more than 36 hours; 5) Pickling: Use push-pull pickling unit with a pickling speed of 152-164m / min; 6) Cold rolling: Using a six-roll reversible rolling mill, hot rolled coil with a thickness of 1.8 to 2.48 mm is rolled through multiple passes to obtain cold rolled sheet with a thickness of 0.08 to 0.18 mm; 7) Continuous annealing: A continuous annealing unit with ROA function is used to carry out annealing in the soaking section, rapid cooling section, secondary heating section, and aging section in sequence. The soaking section has a soaking temperature of 724-751°C, the rapid cooling section cools the temperature to 262-282°C at a cooling rate of 36-40°C / s, the secondary heating section heats to 425-445°C, and the aging section cools to 10-32°C at a cooling rate of 8.5-9.5°C / s. The steel is then cooled in a quenching tank and dried in a drying oven before being discharged from the furnace. 8) Flatness: Flatness elongation is controlled at 1.52% to 1.84%; 9) Tin plating: Using insoluble anode tin plating production line, double-sided tin plating amount is 2.5~3.5 / 2.5~3.5g / m 2 , the tinning speed is 306~326m / min.

6. The method for preparing wide and ultra-thin tinplate according to claim 5, characterized in that: In the step 1), during converter smelting, the weight percentage of molten iron is 51% to 58%, and the weight percentage of scrap steel is 42% to 49%.

7. The method for preparing wide and ultra-thin tinplate according to claim 5, characterized in that: In the step 2), the manganese nitride cored wire contains N: 12% to 15%, Mn: 83% to 84% by mass, and the rest are impurities.

8. The method for preparing wide and ultra-thin tinplate according to claim 5, characterized in that: In the step 3), the fixed length of the continuous casting billet is 10.5 m; and in the step 4), during the hot rolling process, the convexity C40 of the steel strip is controlled to be 5 to 35 μm.

9. The method for preparing wide and ultra-thin tinplate according to claim 5, characterized in that: In step 5), four hydrochloric acid pickling tanks are provided, and the mass concentrations of HCl in pickling tanks 1# to 4# are 5.2% to 7.2%, 10.2% to 13.4%, 15.4% to 17.2%, and 13.6% to 15.8%, respectively.

10. The method for preparing wide and ultra-thin tinplate according to claim 5, characterized in that: In the step 8), a double-stand six-roller leveling machine is used for leveling.

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