Production method of thin cold-rolled strip steel for food cans

Abstract

The invention relates to a production method of thin cold-rolled strip steel for food cans, which comprises the following steps of: smelting molten steel according to preset smelting components, and continuously casting after smelting; the casting blank subjected to continuous casting enters a hot rolling procedure, the final rolling temperature of the casting blank corresponds to the carbon content, and finally hot-rolled strip steel with the thickness of 2.0-2.3 mm is obtained; hot-rolled strip steel enters a rolling procedure after being subjected to acid rolling uncoiling, a five-rack rolling mode is adopted for acid rolling, and the total reduction rate is controlled to be 91%; coiling and then entering a continuous annealing process; in the annealing furnace, the annealing temperature and the strip steel speed are in a proportional relation, and finally finished strip steel is obtained. The thin-gauge strip steel can be produced at a high cold rolling speed, meanwhile, vibration of the rolling mill is effectively relieved, the production cost is reduced, and the product quality is not affected.

Description

Technical Field

[0001] This invention relates to a method for producing thin-gauge cold-rolled strip steel for food cans, belonging to the field of steel material preparation technology, and particularly to the field of cold-rolled strip steel production. Background Technology

[0002] Cold-rolled tinplate is widely used in the production of steel for various food cans due to its thinness and good formability. Currently, with increasing cost pressures and continuous technological advancements, product thickness is trending towards even thinner specifications. However, the production of thin-gauge products faces significant technical bottlenecks. On the one hand, the extremely thin strip steel itself greatly increases the sensitivity to process parameters during rolling. On the other hand, to compensate for the low production efficiency of thin-gauge products, manufacturers typically increase the operating speed of pickling and rolling mills to over 1000 m / min to increase capacity. However, high-speed rolling conditions easily lead to a series of quality and production safety issues, with mill vibration and strip thickness fluctuations being the two most prominent. Mill vibration directly causes periodic thickness fluctuations in the finished strip steel. This defect can further evolve into appearance and dimensional defects such as "bubble waves" in subsequent can-making and coating processes, seriously affecting normal customer use. When the vibration intensity exceeds a critical value, it can even cause strip breakage, resulting in the scrapping of a large number of products, production interruption, and a significant increase in production and equipment maintenance costs.

[0003] To address the aforementioned issues, the common emergency measure adopted in the industry is to reduce the operating speed of thin-gauge pickling mills to below 700 m / min when signs of mill vibration appear, sacrificing production efficiency for production stability and product quality. This passive solution clearly contradicts the current industry trend towards efficient and low-cost production. In related technical fields, some patents have researched the production processes of tinplate or similar galvanized sheets. For example, patent CN117467826A discloses a tinplate for easy-open lids and its manufacturing method. By adopting a low-carbon, low-manganese, and high-nitrogen composition design, it eliminates the need for additional Mn, B, Ti, and other alloys, utilizing N atom precipitation strengthening and solid solution effects to meet customer hardness requirements. Patent CN116103477B discloses a galvanized sheet for milk powder cans and its preparation method. Under set temperature and chemical composition, the final thickness is obtained through hot rolling and cold rolling processes, followed by bell-type annealing, and then leveling to obtain the product.

[0004] However, these existing technologies are all limited in scope. For example, CN117467826A focuses on controlling the hardness of products through chemical composition, but does not address the issues of mill vibration and thickness fluctuation during high-speed rolling. CN116103477B is not suitable for meeting the technical requirements of improving the stability of high-speed rolling in terms of process principles, equipment requirements, and the final control of strip microstructure and properties.

[0005] Therefore, there is a need to provide a production method for cold-rolled ultra-thin strip steel for food cans, which can solve the problem of mill vibration during high-speed production of thin strip steel, and at the same time reduce production costs, so as to facilitate large-scale industrial production. Summary of the Invention

[0006] This invention provides a method for producing thin-gauge cold-rolled strip steel for food cans, which can produce thin-gauge strip steel at a higher cold rolling speed, while effectively reducing mill vibration, lowering production costs, and not affecting product quality.

[0007] The technical solution adopted by this invention to solve its technical problem is: A method for producing thin-gauge cold-rolled strip steel for food cans specifically includes the following steps: Step S1: Smelt steel according to the preset smelting composition, and then continuously cast it after smelting. The preset smelting composition includes the following by mass percentage: C: 0.04-0.06%, Si: 0.01-0.03%, Mn: 0.15-0.25%, P≤0.015%, S≤0.015%, N: ≤0.003%, Als: 0.05-0.07%, Ti: 0.003-0.010%, with the remainder being iron and unavoidable impurity elements. In step S2, the continuously cast billet enters the hot rolling process. The final rolling temperature corresponds to the carbon content. If C ≥ 0.04-0.05, the final rolling temperature is 795℃ ± 10℃. If C ≥ 0.05-0.06, the final rolling temperature is 805℃ ± 10℃. Finally, hot-rolled strip steel with a thickness of 2.0-2.3mm is obtained. Step S3: After the hot-rolled strip is uncoiled by pickling, it enters the rolling process. The pickling process adopts a five-stand rolling mode, controlling the total reduction rate to 91%. The reduction rate of the third stand is 11-14% of the total reduction rate. The diameter and roughness of the rolls of the fifth stand are set. After coiling, it enters the continuous annealing process. The thickness of the pickling raw material is selected and matched according to the finished product target, and the thickness of the finished product is monitored in real time. Step S4: The coiled strip enters the annealing process to finally obtain the finished strip; wherein, in the annealing furnace, the annealing temperature is proportional to the strip speed. Furthermore, in step S1, the steelmaking process, the continuous casting speed is 1.0–1.5 m / min, and the billet thickness is 180–220 mm. Furthermore, in step S2, the hot rolling process, the furnace exit temperature is controlled at 1130–1180°C, and the coiling temperature is set at 660–720°C. Furthermore, in step S3, the diameter of the fifth stand rolls is set to 390-420 mm, and the roughness of the fifth stand rolls is set to 0.45-0.55 μm; Furthermore, in step S3, the cold rolling process, if the finished product thickness is 0.16 to ≤0.18 mm, the pickling raw material thickness is 2.0-2.1 mm; if the finished product thickness is 0.18 to ≤0.19 mm, the pickling raw material thickness is 2.1-2.3 mm; if the finished product thickness is 0.19 to ≤0.20 mm, the pickling raw material thickness is 2.2-2.3 mm. Furthermore, in step S3, the step of real-time monitoring of the finished product thickness is as follows: Step S31: Install a thickness gauge on the fifth frame side; Step S32: Start the thickness gauge and take a measurement every 0.4ms. Collect data once after 5 measurements. Step S33: Smooth the five collected data points, delete the maximum and minimum values, and take the average of the remaining three points as the final finished product thickness. Furthermore, in step S3, the emulsion concentration of the first stand, the second stand, and the third stand are set to be ≥1.8%, and the saponification value is ≥170mgKOH / g; the emulsion concentration of the fourth stand and the fifth stand is ≥6.0%, and the saponification value is controlled at 180-190mgKOH / g. Furthermore, in step S4, the annealing process, the annealing temperature and the strip speed have the following relationship: T = (S / 10-10) + 600, where T is the temperature of the soaking zone of the annealing furnace and S is the strip speed. Furthermore, the hardness range of the finished product is HR30T: 55-65.

[0008] By employing the above technical solutions, the present invention has the following beneficial effects compared to the prior art: 1. The method for producing thin-gauge cold-rolled strip steel for food cans provided by the present invention starts with the raw material composition and firstly makes reasonable improvements to the smelting composition, which can ensure strength while ensuring that costs are not increased. 2. The method for producing thin-gauge cold-rolled strip steel for food cans provided by the present invention effectively improves the rolling stability of cold-rolled thin-gauge strip steel by rationally arranging the production rhythm, optimizing the reduction rate distribution and limiting the saponification value of the emulsion, and optimizing the data collection of the thickness gauge, thereby alleviating problems such as thickness fluctuation and abnormal roll changing caused by mill vibration. Detailed Implementation

[0009] The specific dimensions used in this embodiment are merely illustrative of the technical solution and do not limit the scope of protection of this invention.

[0010] As described in the background section, current technology reduces the operating speed of thin-gauge cold-rolled products to below 700 m / min to avoid defects caused by mill vibration. However, this does not actually provide an effective solution to the problems of mill vibration and thickness fluctuation during the rolling process of thin-gauge cold-rolled sheets. In fact, reducing the operating speed will lead to a decrease in production efficiency, while increasing the roll changing frequency and raising production costs.

[0011] To meet the current industry demand for efficient and stable production of thin-gauge cold-rolled steel sheets, especially for food cans, this application proposes a method for producing thin-gauge cold-rolled strip steel for food cans. Its innovation lies in addressing two aspects: raw material composition and cold rolling process. By rationally arranging the initial rolling material and production rhythm, optimizing the reduction rate distribution, and limiting the saponification value of the emulsion, a uniform load distribution is achieved. Simultaneously, data acquisition and optimization using a thickness gauge improve rolling stability. This alleviates the thickness fluctuations that are common in conventional production methods when producing extremely thin strip steel at high speeds, as well as the unavoidable vibration marks and rolling instability caused by mill vibration. It effectively improves the rolling stability of cold-rolled thin strip steel and mitigates problems such as thickness fluctuations and abnormal roll changes caused by mill vibration.

[0012] The method for producing thin-gauge cold-rolled strip steel for food cans specifically includes the following steps: Step S1: Smelt steel according to the preset smelting composition, and then continuously cast it after smelting. Since this application is aimed at thin-gauge cold-rolled strip steel for food cans, it is necessary to consider that the forming performance of the material should be stable after long-term use, the strength of the can body itself should be high, and the harmful elements should be strictly controlled.

[0013] Preferably, the preset smelting composition provided in this application includes, by mass percentage: C: 0.04–0.06%, Si: 0.01–0.03%, Mn: 0.15–0.25%, P≤0.015%, S≤0.015%, N: ≤0.003%, Als: 0.05–0.07%, Ti: 0.01–0.003%, with the remainder being iron and unavoidable impurities. Under this composition system, the continuous casting speed is set to 1.0–1.5 m / min, and the billet thickness to 180–220 mm to meet production requirements.

[0014] Regarding the design of the content of several important elements in the above-mentioned components, it is necessary to elaborate on them. For example, carbon (C) is an important element for improving the strength of steel, but too high a C content will reduce the plasticity of the steel, affect its formability, and increase the difficulty of rolling; too low a C content will increase the energy consumption of the process, which is not conducive to environmental protection requirements, and at the same time reduce the product strength, failing to meet the requirements for steel used in food cans. In order to achieve a good performance match, the C content in this application is controlled at 0.04% to 0.06%. Within this range, the hardness requirements of the final product can be met. At the same time, due to the thinness of the finished product, within this range, according to the carbon-oxygen product calculation, the oxygen content is lower than that of ultra-low carbon steel, which is more conducive to controlling the inclusion content.

[0015] Si is a ferrite-forming element that can improve the strength of solid solutions in steel, with a more significant effect on increasing the tensile strength of steel. For mild steel, increasing the Si content is detrimental to improving formability, while too low a content is detrimental to surface quality control. Therefore, the Si content in this application is set at 0.01–0.03%.

[0016] Mn is one of the important solid solution strengthening elements in steel and also an austenite stabilizing element. It can expand the austenite region in the iron-carbon phase diagram, promote the mid-temperature microstructure transformation of steel, and obtain a microstructure dominated by acicular structures. This microstructure has good uniformity, excellent weather resistance, and high strength and toughness. However, excessive Mn content will not only reduce elongation and impair the toughness of steel, but also reduce its corrosion resistance and weldability, while increasing manufacturing costs. Therefore, in this application, the Mn content is controlled at 0.15-0.25%, which is the residual Mn content in steelmaking. There is no need to deliberately add Mn; the performance is controlled through subsequent processes.

[0017] The most significant innovation in the above composition settings lies in the element Ti. Ti can play a role in precipitation strengthening, refining the strip grains and reducing grain anisotropy, thereby reducing strip anisotropy. Experiments have shown that within the final rolling temperature range, when the Ti content is below 0.003%, the strength of the hot-rolled strip drops sharply. However, when the Ti content is ≥0.003%, the strength of the hot-rolled strip is ensured without drastic fluctuations. Excessive Ti content increases strength but also raises costs. Therefore, in this application, the Ti content is 0.003–0.010%, with an optimal content of 0.003–0.005%. This ensures strength without increasing costs. Currently, in most cases, the residual Ti content of the steel grade is sufficient to meet the requirements.

[0018] In step S2, the continuously cast billet enters the hot rolling process. The furnace exit temperature is controlled at 1130–1180℃. The final rolling temperature is one of the main control parameters of this application and is also the innovation of this application. Since the performance is highly sensitive to temperature control and the carbon content range is narrow, there is a corresponding relationship between the final rolling temperature and the carbon content, as follows: If C ≥ 0.04-0.05, then the final rolling temperature is 795℃ ± 10℃. If C ≥ 0.05-0.06, then the final rolling temperature is 805℃ ± 10℃; The coiling temperature is set to 660-720℃, and a hot-rolled strip with a thickness of 2.0-2.3mm is finally obtained.

[0019] Step S3: After the hot-rolled strip is uncoiled by pickling, it enters the rolling process. Based on current pickling statistics, thinner strips are more prone to vibration; for example, the maximum speed difference between 0.18mm and 0.19mm strips can be 150m / min. A higher reduction rate also leads to greater instability. Therefore, this application employs a five-stand rolling mode for pickling, controlling the total reduction rate to approximately 91%. Because the third stand has fewer roll changes, while the fourth and fifth stands have more frequent changes and higher surface roughness after roll changes, the high reduction rate of the third stand can alleviate the problem of uneven rolling force distribution during the rolling process. Therefore, the reduction rate of the third stand is 11-14% of the total reduction rate, which can alleviate the problem of uneven rolling force distribution between stands. The roll diameter of the fifth stand is set at 390-420mm. A roll diameter that is too large results in high rolling force, which is detrimental to rolling stability; a roll diameter that is too small leads to rapid roll wear. Meanwhile, the surface roughness of the fifth stand rolls is set to 0.45-0.55μm. By using a higher surface roughness and a lower roll diameter, the shear stress is increased, the roll slippage phenomenon is reduced, and the rolling stability is improved.

[0020] Since the thickness of the pickling and rolling raw material needs to be matched and selected according to the target finished product, real-time monitoring of the finished product thickness is required. To ensure the accuracy of the data acquired in real-time monitoring, a thickness gauge is preferably installed on the fifth stand side. The thickness gauge is started and measures once every 0.4ms, so 2500 measurements can be taken per second. After 5 measurements, a data acquisition is performed, which is equivalent to acquiring data once every 2ms, or 500 times per second, forming a closed-loop control with AGC. Next, the 5 acquired data points need to be processed. This is because if the mill exit speed is 1200m / min, the thickness gauge can take 2500 measurements over a 20m length in 1 second, which is equivalent to measuring one point every 8mm and acquiring data at one point every 40mm. However, in reality, it is difficult for the mill to show significant thickness changes within 8mm. The 5 acquired data points are smoothed by deleting the maximum and minimum values ​​and taking the average of the remaining 3 points, which is the final finished product thickness. It can effectively avoid thickness abnormalities caused by local high points in the centerline position that are distorted during measurement, thereby improving the overshoot phenomenon of the fourth and fifth stands, maintaining roll gap stability, reducing thickness fluctuations, and at the same time reducing the risk of mill vibration and ensuring high-speed operation of the mill.

[0021] In actual production, if the raw material is too thick, it can easily lead to overload of the rolling mill and uneven elastic deformation of the rolls. If the raw material is too thin, it is impossible to fully refine the grains and improve the uniformity of the microstructure through cold rolling. Therefore, another innovation of this application is that the thickness of the pickling and rolling raw material needs to be matched and selected according to the finished product target. By accurately selecting the raw material thickness, the total reduction rate can be controlled within the optimal range. Combined with AGC closed-loop control, it can be ensured that the thickness tolerance of the finished product is stable within the preset range.

[0022] Preferably, if the finished product thickness is 0.16 to ≤0.18 mm, the thickness of the pickling and rolling raw material is 2.0-2.1 mm; if the finished product thickness is 0.18 to ≤0.19 mm, the thickness of the pickling and rolling raw material is 2.1-2.3 mm; if the finished product thickness is 0.19 to ≤0.20 mm, the thickness of the pickling and rolling raw material is 2.2-2.3 mm.

[0023] During the pickling process, the emulsion concentration needs to be precisely controlled by each stand. Therefore, the emulsion concentration of the first stand, the second stand and the third stand are set to be ≥1.8% and the saponification value is ≥170mgKOH / g; the emulsion concentration of the fourth stand and the fifth stand is ≥6.0% and the saponification value is controlled at 180-190mgKOH / g.

[0024] Step S4: The coiled strip enters the annealing process. In order to ensure the hardness of the strip, there is a proportional relationship between the annealing temperature and the strip speed. Generally, the speed in the annealing furnace is between 200-700 m / min, which can be simply expressed as follows: T=(S / 10-10)+600, where T is the temperature of the soaking zone of the annealing furnace and S is the strip speed.

[0025] Through the above controls, the final finished product hardness range is HR30T: 55-65, which alleviates the decline in strip strength and stabilizes the production of cold-rolled food can steel with a thickness of 0.2mm and below, meeting customer needs.

[0026] The following embodiments 1-3 are provided to demonstrate the feasibility and superiority of the method for producing thin-gauge cold-rolled strip steel for food cans provided in this application.

[0027] Example 1

[0028] Step S1, smelting composition: C: 0.042%, Si: 0.011%, Mn: 0.16%, P: 0.011%, S: 0.003%, N: 0.002%, Als: 0.051%, Ti: 0.0034%, with the remainder being iron and unavoidable impurities. Steel is smelted according to the above composition requirements; the performance meets production needs under this composition system. Continuous casting speed is 1.1 m / min, and billet thickness is 220 mm.

[0029] Step S2: Hot rolling exit temperature 1140℃; final rolling temperature: 796℃; coiling temperature 668℃; hot rolling thickness 2.0mm.

[0030] Step S3: To ensure product performance, the total rolling reduction rate is maintained at approximately 91%, with the reduction rate of the third stand controlled at 12% of the total reduction rate. Raw material thickness selected: 2.0 mm; Finished product thickness: 0.18 mm. The five-stand configuration is adopted, in which the working roll diameter of the fifth stand is 394mm and the roll roughness is 0.45μm.

[0031] Thickness gauges are installed before and after the fifth stand. Each gauge measures every 0.4 ms, and a single data acquisition is performed after five measurements, equivalent to a data acquisition every 2 ms. The five data points are smoothed by deleting the maximum and minimum values, and averaging the remaining three. This effectively prevents thickness anomalies caused by localized high points at the centerline, thereby improving overshoot in the fourth and fifth stands, maintaining roll gap stability, reducing thickness fluctuations, mitigating mill vibration risks, and ensuring high-speed mill operation. Emulsion saponification value: The emulsion concentration of the first stand, the second stand and the third stand is 2.0%, and the saponification value is 175 mg KOH / g; the emulsion concentration of the fourth stand and the fifth stand is 6.2%, and the saponification value is 184 mg KOH / g.

[0032] Step S4, Annealing temperature: To ensure the hardness of the strip, the annealing temperature is proportional to the speed. Generally, the speed in the annealing furnace is 240m / min, so the annealing temperature is 614℃.

[0033] Through the above controls, the final product hardness range is HR30T:58, which meets customer requirements.

[0034] Example 2

[0035] Step S1, smelting composition: C: 0.059%, Si: 0.026%, Mn: 0.24%, P: 0.015%, S: 0.008%, N: 0.003%, Als: 0.064%, Ti: 0.008%, with the remainder being iron and unavoidable impurities. Steel is smelted according to the above composition requirements; the performance meets production needs under this composition system. Continuous casting speed is 1.2 m / min, and billet thickness is 220 mm. Step S2: Hot rolling exit temperature 1150℃; final rolling temperature: 802℃; coiling temperature 696℃; hot rolling thickness 2.2mm; Step S3: To ensure product performance, the total rolling reduction rate is maintained at approximately 91%, with the reduction rate of the third stand controlled at 13% relative to the total reduction rate. Raw material thickness selected: 2.2 mm; Finished product thickness: 0.19 mm. The five-stand configuration is adopted, in which the working roll diameter of the fifth stand is 423mm and the roll roughness is 0.48μm.

[0036] Thickness gauges are installed before and after the fifth stand. Each gauge measures every 0.4 ms, and a single data acquisition is performed after five measurements, equivalent to a data acquisition every 2 ms. The five data points are smoothed by deleting the maximum and minimum values, and averaging the remaining three. This effectively prevents thickness anomalies caused by localized high points at the centerline, thereby improving overshoot in the fourth and fifth stands, maintaining roll gap stability, reducing thickness fluctuations, mitigating mill vibration risks, and ensuring high-speed mill operation.

[0037] Emulsion saponification value: The emulsion concentration of the first stand, the second stand, and the third stand is 2.4%, and the saponification value is 180 mg KOH / g; the emulsion concentration of the fourth stand and the fifth stand is 6.6%, and the saponification value is 187 mg KOH / g.

[0038] Step S4, Annealing temperature: To ensure the hardness of the strip, the annealing temperature is proportional to the speed. Generally, the speed in the annealing furnace is 560m / min, so the annealing temperature is 646℃.

[0039] Through the above controls, the final product hardness range is HR30T:61, which meets customer requirements.

[0040] Example 3

[0041] Step S1, smelting composition: C: 0.056%, Si: 0.019%, Mn: 0.20%, P: 0.009%, S: 0.011%, N: 0.003%, Als: 0.057%, Ti: 0.007%, with the remainder being iron and unavoidable impurities. Steel is smelted according to the above composition requirements; the performance meets production needs under this composition system. Continuous casting speed is 1.3 m / min, and billet thickness is 220 mm. Step S2: Hot rolling exit temperature 1160℃. Final rolling temperature: 806℃, coiling temperature 701℃; hot rolling thickness 2.3mm; Step S3: To ensure product performance, the total rolling reduction rate is maintained at approximately 91%, with the reduction rate of the third stand controlled at 14% of the total reduction rate. Raw material thickness selected: 2.3 mm; Finished product thickness: 0.20 mm. The five-stand configuration is adopted, in which the working roll diameter of the fifth stand is 431mm and the roll roughness is 0.50μm.

[0042] Thickness gauges are installed before and after the fifth stand. Each gauge measures every 0.4 ms, and a single data acquisition is performed after five measurements, equivalent to a data acquisition every 2 ms. The five data points are smoothed by deleting the maximum and minimum values, and averaging the remaining three. This effectively prevents thickness anomalies caused by localized high points at the centerline, thereby improving overshoot in the fourth and fifth stands, maintaining roll gap stability, reducing thickness fluctuations, mitigating mill vibration risks, and ensuring high-speed mill operation.

[0043] Emulsion saponification value: The emulsion concentration of the first stand, the second stand and the third stand is 2.3%, and the saponification value is 179 mg KOH / g; the emulsion concentration of the fourth stand and the fifth stand is 6.4%, and the saponification value is 189 mg KOH / g.

[0044] Step S4, Annealing temperature: To ensure the hardness of the strip, the annealing temperature is proportional to the speed. Generally, the speed in the annealing furnace is 670m / min, so the annealing temperature is 657℃.

[0045] Through the above controls, the final product hardness range is HR30T:60, which meets customer requirements.

[0046] In summary, the method for producing thin-gauge cold-rolled strip steel for food cans provided in this application can produce thin-gauge strip steel at a relatively high cold rolling speed, while effectively reducing mill vibration, lowering production costs, and without affecting product quality.

[0047] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0048] The meaning of "and / or" as used in this application includes situations where each exists alone or both exist simultaneously.

[0049] The term "connection" as used in this application can mean a direct connection between components or an indirect connection between components through other components.

[0050] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for producing thin-gauge cold-rolled strip steel for food cans, characterized in that: Specifically, the following steps are included: Step S1: Smelt steel according to the preset smelting composition, and then continuously cast it after smelting. The preset smelting composition includes the following by mass percentage: C: 0.04-0.06%, Si: 0.01-0.03%, Mn: 0.15-0.25%, P≤0.015%, S≤0.015%, N: ≤0.003%, Als: 0.05-0.07%, Ti: 0.003-0.010%, with the remainder being iron and unavoidable impurity elements. In step S2, the continuously cast billet enters the hot rolling process. The final rolling temperature corresponds to the carbon content. If C ≥ 0.04-0.05, the final rolling temperature is 795℃ ± 10℃. If C ≥ 0.05-0.06, the final rolling temperature is 805℃ ± 10℃. Finally, hot-rolled strip steel with a thickness of 2.0-2.3mm is obtained. Step S3: After the hot-rolled strip is uncoiled by pickling, it enters the rolling process. The pickling process adopts a five-stand rolling mode, controlling the total reduction rate to 91%. The reduction rate of the third stand is 11-14% of the total reduction rate. The diameter and roughness of the rolls of the fifth stand are set. After coiling, it enters the continuous annealing process. The thickness of the pickling raw material is selected and matched according to the finished product target, and the thickness of the finished product is monitored in real time. In step S4, the coiled strip enters the annealing process to finally obtain the finished strip; wherein, in the annealing furnace, the annealing temperature is proportional to the strip speed.

2. The method for producing thin-gauge cold-rolled strip steel for food cans according to claim 1, characterized in that: In step S1, the steelmaking process, the continuous casting speed is 1.0 to 1.5 m / min, and the billet thickness is 180 to 220 mm.

3. The method for producing thin-gauge cold-rolled strip steel for food cans according to claim 1, characterized in that: In step S2, the hot rolling process, the furnace exit temperature is controlled at 1130-1180℃, and the coiling temperature is set at 660-720℃.

4. The method for producing thin-gauge cold-rolled strip steel for food cans according to claim 1, characterized in that: In step S3, the diameter of the fifth stand rolls is set to 390-420 mm, and the roughness of the fifth stand rolls is set to 0.45-0.55 μm.

5. The method for producing thin-gauge cold-rolled strip steel for food cans according to claim 1, characterized in that: In step S3, the cold rolling process, if the finished product thickness is 0.16 to ≤0.18 mm, the pickling raw material thickness is 2.0-2.1 mm; if the finished product thickness is 0.18 to ≤0.19 mm, the pickling raw material thickness is 2.1-2.3 mm; if the finished product thickness is 0.19 to ≤0.20 mm, the pickling raw material thickness is 2.2-2.3 mm.

6. The method for producing thin-gauge cold-rolled strip steel for food cans according to claim 1, characterized in that: In step S3, the real-time monitoring of the finished product thickness is as follows: Step S31: Install a thickness gauge on the fifth frame side; Step S32: Start the thickness gauge and take a measurement every 0.4ms. Collect data once after 5 measurements. Step S33: Smooth the five collected data points, delete the maximum and minimum values, and take the average of the remaining three points as the final finished product thickness.

7. The method for producing thin-gauge cold-rolled strip steel for food cans according to claim 1, characterized in that: In step S3, the emulsion concentration of the first stand, the second stand, and the third stand are set to be ≥1.8%, and the saponification value is ≥170mgKOH / g; the emulsion concentration of the fourth stand and the fifth stand is ≥6.0%, and the saponification value is controlled at 180-190mgKOH / g.

8. The method for producing thin-gauge cold-rolled strip steel for food cans according to claim 1, characterized in that: In step S4, the annealing process, the annealing temperature and the strip speed have the following relationship: T = (S / 10-10) + 600, where T is the temperature of the soaking zone of the annealing furnace and S is the strip speed.

9. The method for producing thin-gauge cold-rolled strip steel for food cans according to claim 1, characterized in that: The hardness range of the finished product is HR30T: 55-65.