Preparation method of low-temperature hot-rolled strip steel for forming

Abstract

The invention relates to a preparation method of low-temperature hot-rolled strip steel for forming, and belongs to the technical field of hot rolling processes. The method comprises the following steps: heating a continuous casting billet, and controlling the following heating parameters: soaking time, tapping temperature and in-furnace time; the heated continuous casting billet is sequentially subjected to rough rolling and cooling, and an intermediate billet is obtained; and the intermediate billet is subjected to finish rolling, laminar cooling and coiling in sequence, and the low-temperature hot-rolled strip steel is obtained, wherein double rows of descaling are used before finish rolling, cooling water and descaling water between racks are closed during finish rolling, and rolling lubricating oil is used, so that the surface layer shear texture strength is reduced, and the stamping performance is improved. By optimizing heating process parameters, uniform temperature distribution of the steel in the thickness direction is ensured, the structure layering phenomenon is avoided, and by optimizing rolling process parameters, one-way shearing stress on the surface of the strip steel is reduced, so that distribution of micro textures is improved, and the stamping performance is improved.

Description

Technical Field

[0001] The present application relates to the technical field of hot rolling process, and in particular to a method for preparing low-temperature hot-rolled strip steel for forming. Background Art

[0002] As a material with huge demand, hot-rolled low-carbon steel has shown broad application prospects in many fields such as automobile manufacturing and household appliances. This type of steel has extremely high requirements for the uniformity of the organizational structure, stamping performance and surface quality. However, when using the traditional hot-rolled strip production process, although the product can be produced through the conventional rolling process, in the subsequent pickling process, there are often problems of surface color difference and easy cracking of the edges during the stamping process, and the cracking rate is as high as about 30%, which seriously restricts the quality and application range of the product. In order to overcome this technical difficulty, the industry began to explore new methods that can replace traditional production processes, among which low-temperature rolling technology has attracted much attention due to its unique advantages. A major feature of low-temperature rolling technology is that it can form a thinner iron oxide scale, which helps to improve the surface quality of steel. In addition, this technology also performs better in terms of yield strength ratio, which helps to improve the mechanical properties and processing performance of steel.

[0003] However, when low-temperature rolling technology is actually applied, the two-phase window width of low-carbon steel is relatively large, which places extremely high demands on process control. If the process parameters of low-temperature rolling are not set properly, the temperature distribution of the steel in the thickness direction may become uneven, resulting in the surface layer being rolled in the ferrite zone, while the core is still in the low-temperature austenite zone. This temperature difference can easily cause the problem of organizational stratification. In addition, the large number of reduction operations and the low rolling temperature during hot rolling will cause significant unidirectional shear stress on the surface of the strip, which in turn has a profound impact on the stress distribution in the thickness direction and the formation of microtexture. Specifically, it is manifested as the enhancement of the surface shear texture. This texture change is unfavorable for the stamping performance of steel. Summary of the invention

[0004] The present application provides a method for preparing low-temperature hot-rolled strip steel for forming, in order to solve the following technical problem: how to use low-temperature rolling technology to prepare hot-rolled strip steel with good surface quality and stamping performance.

[0005] The present application provides a method for preparing a low-temperature hot-rolled strip steel for forming, the method comprising:

[0006] The continuous casting billet is heated, and the following heating parameters are controlled: soaking time, tapping temperature and time in the furnace;

[0007] The heated continuous casting billet is subjected to rough rolling and cooling in sequence to obtain an intermediate billet.

[0008] The intermediate billet is sequentially subjected to finish rolling, laminar cooling and coiling to obtain the low-temperature hot-rolled strip steel; double descaling is used before the finish rolling, the cooling water and descaling water between the frames are closed during the finish rolling, and rolling lubricating oil is used to reduce the surface shear texture strength and improve the stamping performance.

[0009] Optionally, the chemical composition of the continuous casting billet includes, by mass fraction: C: 0.02% to 0.06%, Si: 0% to 0.03%, Mn: 0.1% to 0.4%, P≤0.015%, S≤0.015%, and matrix element Fe.

[0010] Optionally, the soaking time is 30 min to 50 min.

[0011] Optionally, the steel tapping temperature is 950°C to 1050°C.

[0012] Optionally, the time in the furnace is 120 min to 300 min.

[0013] Optionally, the outlet temperature of the rough rolling is 870°C to 900°C.

[0014] Optionally, the finishing rolling equipment comprises 7 stands F1 to F7, the pass reduction ratio of stands F1 to F3 is 30% to 45%, and the pass reduction ratio of stand F7 is >15%.

[0015] Optionally, the concentration of the rolling lubricant oil is 0.3% to 0.6%.

[0016] Optionally, the inlet temperature of the finishing rolling is 800°C to 860°C, and the terminal temperature of the finishing rolling is 750°C to 800°C.

[0017] Optionally, the coiling temperature is 620°C to 700°C.

[0018] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0019] The embodiment of the present application provides a method for preparing low-temperature hot-rolled strip steel for forming, the method comprising: heating the continuous casting billet and controlling the following parameters of the heating: soaking time, steel tapping temperature and furnace time; rough rolling and cooling the heated continuous casting billet in sequence to obtain an intermediate billet; finishing rolling, laminar cooling and coiling the intermediate billet in sequence to obtain the low-temperature hot-rolled strip steel; wherein, double descaling is used before finishing rolling, the cooling water and descaling water between the frames are closed during finishing rolling, and rolling lubricating oil is used to reduce the surface shear texture strength and improve the stamping performance. By optimizing the heating process parameters, the temperature distribution of the steel in the thickness direction is ensured to be uniform, and the occurrence of organizational stratification is avoided. By optimizing the rolling process parameters, the generation of unidirectional shear stress on the strip surface is reduced, thereby improving the distribution of microtexture, which is beneficial to improving the stamping performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 A schematic flow chart of a method for preparing a low-temperature hot-rolled strip steel for forming provided in an embodiment of the present application;

[0023] Figure 2 The metallographic structure diagram provided for the comparative example of this application;

[0024] Figure 3 This is a metallographic structure diagram provided for an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0026] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0027] In this document, the terms including "including" and "including" mean "including but not limited to". Relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "plurality" means two or more; "at least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items; for example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the mass ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond to the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0028] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0029] Figure 1 A schematic flow chart of a method for preparing a low-temperature hot-rolled strip steel for forming provided in an embodiment of the present application.

[0030] like Figure 1 As shown, the embodiment of the present application provides a method for preparing low-temperature hot-rolled strip steel for forming, the method comprising:

[0031] S1, heating the continuous casting billet, and controlling the following parameters of the heating: soaking time, tapping temperature and furnace time;

[0032] First, the continuous casting billet is heated. During this process, several key parameters of heating are strictly controlled - soaking time, tapping temperature and time in the furnace. The precise control of these parameters is crucial to ensure the subsequent processing performance of the steel and the quality of the final product. By optimizing the heating parameters, the temperature distribution of the steel in the thickness direction is ensured to be uniform. This measure effectively avoids the occurrence of organizational stratification and makes the internal structure of the steel more uniform and stable.

[0033] In some embodiments, the chemical composition of the continuous casting billet includes, by mass fraction: C: 0.02% to 0.06%, Si: 0% to 0.03%, Mn: 0.1% to 0.4%, P≤0.015%, S≤0.015%, and matrix element Fe.

[0034] The chemical composition of the continuous casting billet needs to be precisely controlled to ensure the performance of the steel. The mass fraction of C has a great influence on the strength, toughness and plasticity of the steel. In the embodiment of the present application, a mass fraction of C exceeding 0.06% will increase the rolling force and affect the rolling stability. Therefore, the mass fraction of C is controlled within the range of 0.02% to 0.06% to maintain a balance between the strength and toughness of the steel. Exemplarily, the mass fraction of C can be 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, etc.

[0035] Fe is a matrix element. The specific content / content range of Fe can be obtained by the upper and lower limit formula of the component, that is:

[0036] The sum of the percentages of the contents of each component in a composition should be equal to 100%, and the content ranges of several components should meet the following conditions: the upper limit value of a component + the lower limit value of other components ≤ 100; the lower limit value of a component + the upper limit value of other components ≥ 100.

[0037] In some embodiments, the soaking time is 30 min to 50 min.

[0038] The length of the soaking time determines the degree of temperature uniformity achieved by the continuous casting billet in the heating furnace. If the soaking time is less than 30 minutes, there may still be a temperature gradient inside the continuous casting billet, resulting in uneven microstructure, which in turn affects the stability of the subsequent rolling process and the performance of the final product. On the contrary, if the soaking time exceeds 50 minutes, although it can ensure that the temperature inside the continuous casting billet is more uniform, it will also increase energy consumption and production time, and reduce production efficiency. In addition, too long soaking time may also cause coarsening of the surface grains of the continuous casting billet, which will have an adverse effect on the performance of the final product. Therefore, it is a reasonable choice to control the soaking time between 30 minutes and 50 minutes. This range can not only ensure uniform temperature inside the continuous casting billet, but also avoid too long heating time and excessive energy consumption. At the same time, this range also provides a certain flexibility for actual production, which can be adjusted according to specific production conditions and product requirements. Exemplarily, the soaking time can be 30min, 34min, 38min, 42min, 46min, 50min, etc.

[0039] In some embodiments, the tapping temperature is 950°C to 1050°C.

[0040] The tapping temperature refers to the temperature when the continuous casting billet is discharged from the heating furnace. The temperature determines the plasticity and deformation ability of the continuous casting billet in the subsequent rolling process, and also affects the microstructure and performance of the final product. Setting the tapping temperature between 950°C and 1050°C can, on the one hand, ensure that the continuous casting billet is fully heated in the heating furnace, so that its internal temperature is uniform, and the microstructure undergoes a transformation that is conducive to rolling; it can also improve the plasticity and deformation ability of the continuous casting billet during the rolling process, thereby ensuring the stability and continuity of rolling. Exemplarily, the tapping temperature can be 950°C, 970°C, 990°C, 1010°C, 1030°C, 1050°C, etc.

[0041] In some embodiments, the time in the furnace is 120 min to 300 min.

[0042] The time in the furnace refers to the total time required for the continuous casting billet to enter the heating furnace and be discharged from the heating furnace. The length of this time directly affects the temperature change and microstructural evolution of the continuous casting billet during the heating process. Setting the furnace time between 120 minutes and 300 minutes can ensure that the continuous casting billet has enough time in the heating furnace to reach the predetermined heating temperature and make its internal temperature evenly distributed. Although a longer time in the furnace can ensure that the continuous casting billet is heated more fully, it will also increase energy consumption and production costs. At the same time, too long a time in the furnace may also cause the surface grains of the continuous casting billet to coarsen, which will have an adverse effect on the performance of the final product. Exemplarily, the time in the furnace can be 120min, 150min, 180min, 210min, 240min, 270min, 300min, etc.

[0043] S2, sequentially rough rolling and cooling the heated continuous casting billet to obtain an intermediate billet;

[0044] The heated continuous casting billet undergoes a rough rolling process and then cools to obtain an intermediate billet. This step helps to adjust the shape and size of the steel, while the cooling process can further control the internal structure and properties of the steel.

[0045] In some embodiments, the outlet temperature of the rough rolling is 870°C to 900°C.

[0046] The outlet temperature of rough rolling is set between 870℃ and 900℃, so that the microstructure of the intermediate billet can be effectively homogenized, which is conducive to the subsequent finishing process. If the outlet temperature of rough rolling is too low, the structure of the intermediate billet may be uneven during rolling in the low temperature zone, affecting subsequent processing; if the temperature is too high, the intermediate billet may be water-cooled too much, affecting the uniformity of temperature distribution in the thickness direction. For example, the outlet temperature of rough rolling can be 870℃, 875℃, 880℃, 885℃, 900℃, etc.

[0047] S3. The intermediate billet is sequentially subjected to finish rolling, laminar cooling and coiling to obtain the low-temperature hot-rolled steel strip; wherein, double descaling is used before the finish rolling, the cooling water and descaling water between the frames are closed during the finish rolling, and rolling lubricating oil is used to reduce the surface shear texture strength and improve the stamping performance.

[0048] Before finishing rolling, double descaling is mainly used to remove the iron oxide scale and other impurities on the surface of the intermediate billet; closing the cooling water and descaling water between the racks during finishing rolling can prevent the temperature of the intermediate billet from dropping due to cooling during the rolling process, thereby maintaining its temperature uniformity, which is crucial to ensure the stability of the subsequent rolling process and product quality. During the rolling process, due to the friction and shearing effect between the metals, a certain shear texture will be formed on the surface of the strip, which may affect the mechanical properties and surface quality of the strip. The use of rolling lubricants can reduce the friction coefficient between the metals, thereby reducing the formation of shear textures. Rolling lubricants can also play a lubricating role and reduce the friction resistance between the rolls and the strip, which helps to reduce rolling pressure, reduce energy consumption, and extend the service life of the rolls. By reducing friction and shearing, rolling lubricants can also improve the surface quality of the strip, making it smoother and flatter.

[0049] In some embodiments, the concentration of the rolling lubricant is 0.3% to 0.6%.

[0050] Too high or too low a concentration of rolling lubricant may affect its lubrication effect. In the embodiment of the present application, the concentration of rolling lubricant is reasonably controlled to be 0.3% to 0.6% to ensure that it can play the best lubrication effect. For example, the concentration of rolling lubricant can be 0.3%, 0.4%, 0.5%, 0.6%, etc.

[0051] In some embodiments, the finishing rolling equipment comprises 7 stands F1 to F7, the pass reduction ratio of stands F1 to F3 is 30% to 45%, and the pass reduction ratio of stand F7 is >15%.

[0052] In the embodiment of the present application, the finishing rolling equipment includes 7 stands (F1 to F7), and such a setting can provide sufficient rolling passes to ensure that the strip obtains the required deformation and microstructure during the rolling process. Each stand undertakes a specific rolling task and works together to complete the entire finishing rolling process.

[0053] The pass reduction rate of stands F1 to F3 is set between 30% and 45%. This range can ensure that the strip obtains sufficient deformation in these stands, thereby refining the grains, improving the permeability of compression deformation, and improving the uniformity of the structure in the thickness direction. When the pass reduction rate of stands F1 to F3 is >45%, the rolling force increases, which is not conducive to the bite and rolling stability control. Exemplarily, the pass reduction rate of stands F1 to F3 can be 30%, 33%, 36%, 39%, 42%, 45%, etc. The pass reduction rate of stand F7 is set to be greater than 15% to ensure that the strip obtains sufficient deformation in the last stand, the distortion energy is increased, the driving force of grain recrystallization in the layer cooling stage is improved, and a good foundation is provided for the subsequent coiling process. Exemplarily, the pass reduction rate of stand F7 can be 16%, 17%, 18%, 19%, 20%, 21%, 22%, etc.

[0054] In some embodiments, the inlet temperature of the finish rolling is 800°C to 860°C, and the terminal temperature of the finish rolling is 750°C to 800°C.

[0055] The inlet temperature of finishing rolling refers to the temperature before the strip enters the finishing mill. When the inlet temperature of finishing rolling is controlled within 860°C, the surface and core of the intermediate billet can be transformed from the austenite state to the ferrite state. The ferrite precipitated first forms a large number of dislocations and substructures in the crystal after deformation, and the rear-stage rack can also obtain an ideal ferrite rolling effect. At the same time, the inlet temperature of finishing rolling higher than 860°C may also aggravate the thermal deformation and oxidation during the rolling process, thereby affecting the surface quality of the strip, such as the generation of defects such as iron oxide scale. If the inlet temperature of finishing rolling is lower than 800°C, the plasticity of the strip may be reduced, resulting in too fast a speed of finishing rolling, affecting the stability and continuity of rolling. In addition, the inlet temperature of finishing rolling lower than 800°C may also affect the hit rate of the final rolling temperature, that is, the expected temperature range reached by the strip after the finishing rolling. For example, the inlet temperature of finishing rolling can be 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, etc.

[0056] The end temperature of finishing rolling refers to the final temperature reached by the strip after passing through the finishing mill. When the end temperature of finishing rolling is lower than 750°C, the ferrite inside the strip may not be fully recrystallized, thereby retaining the fibrous structure formed during the finishing rolling process. This structure will affect the stamping performance and toughness of the strip. In order to obtain good stamping performance, the strip needs to undergo a sufficient recrystallization process to eliminate the fibrous structure. If the exit temperature of finishing rolling is higher than 800°C, the surface of the strip may be transformed into partial ferrite, while the core is still in the austenite state. This difference will cause the strip to have a stratified structure in the thickness direction. Structural stratification will affect the mechanical properties and processing properties of the strip, especially in processes such as stamping and deep drawing. Exemplarily, the end temperature of finishing rolling can be 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, etc.

[0057] In some embodiments, the coiling temperature is 620°C to 700°C.

[0058] When the coiling temperature is too low (<620°C), the grains inside the strip may not be fully recrystallized, and the strip may also maintain a fibrous ferrite structure. This organizational form usually has a higher hardness and lower toughness, which is not conducive to subsequent processing such as stamping and stretching of the strip. The fibrous ferrite structure may also cause cracks and fractures in the strip during the stamping process. When the coiling temperature is too high (>700°C), the iron oxide scale on the surface of the strip may thicken. This is because iron reacts more violently with oxygen in the air at high temperatures, forming more iron oxide scale. Thicker iron oxide scale not only affects the surface quality of the strip, but also may reduce the strength and toughness of the strip. Too high (>700°C) coiling temperature may also cause changes in the organizational structure inside the strip, such as grain growth, thereby affecting the strength of the strip. Exemplarily, the coiling temperature can be 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, etc.

[0059] The present application is further described below in conjunction with specific examples. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are measured in accordance with common international standards, conventional conditions or conditions recommended by the manufacturer.

[0060] The present application provides a method for preparing a low-temperature hot-rolled strip steel for forming, comprising:

[0061] The continuous casting billet is heated, and the following heating parameters are controlled: soaking time, tapping temperature and time in the furnace;

[0062] The heated continuous casting billet is subjected to rough rolling and cooling in sequence to obtain an intermediate billet;

[0063] The intermediate billet is sequentially subjected to finish rolling, laminar cooling and coiling to obtain the low-temperature hot-rolled steel strip; wherein the cooling water and descaling water between the stands are turned off during the finish rolling, and rolling lubricating oil is used to reduce the shear texture strength of the surface layer and improve the stamping performance. The chemical composition of the continuous casting billet is shown in Table 1, and the specific process parameters are shown in Table 2.

[0064] Table 1 Chemical composition of continuous casting slab (wt%)

[0065] Group C Si Mn P S Thickness of low temperature hot rolled strip steel (mm) Example 1 0.04 0.02 0.34 0.01 0.003 2.5 Example 2 0.036 0.005 0.21 0.01 0.005 5 Example 3 0.047 0.004 0.23 0.006 0.009 3 Comparative Example 1 0.042 0.006 0.32 0.008 0.01 2.5

[0066] Table 2

[0067]

[0068] The performance of the low-temperature hot-rolled steel strips produced in the above-mentioned embodiments and comparative examples was tested, and the results are shown in Table 3.

[0069] Table 3

[0070]

[0071] As can be seen from Tables 1 to 3, the chemical composition and preparation process parameters of the embodiments are all within the required range of the present invention, the surface quality is significantly improved, the thickness of the surface oxide scale is controlled between 3.1-5.3μm, and there is no color difference problem on the surface quality after pickling; and the prepared hot-rolled strip for forming has uniform structure, excellent stamping performance, low yield strength ratio, and no cracking problem on the edge stamping in batch production. The comparative example is an austenite rolled strip with the same composition, the thickness of the scale is between 7.4-9.3μm, the oxide scale on the edge falls off, and there is a color difference problem on the surface after pickling. The product of the embodiment has a lower yield strength ratio and better surface quality.

[0072] Attached Figure 2-3 Detailed description:

[0073] Figure 2 The metallographic structure diagram provided for the comparative example of this application is: Figure 3 The metallographic structure diagram provided by the embodiment of the present application; Figure 2 , Figure 3 It can be seen that the hot-rolled strip steel for forming prepared in the embodiment has uniform structure in the thickness direction.

[0074] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0075] The low-temperature rolling steel-out temperature of the embodiment of the present invention is reduced by about 200°C, and the burning rate is reduced by 0.03% for every 10°C reduction. Calculated based on the hot coil price of 3220 yuan, the cost loss can be reduced by 200°C / 10°C*0.03%*3220 yuan / ton=19.32 yuan / ton; reducing the temperature by 10°C per ton of steel reduces energy consumption by about 0.9kgce / t, saving energy cost of 0.3 yuan, a total of 200°C / 10°C*0.3 yuan=6 yuan / ton, and the comprehensive cost reduction per ton of steel is 25.32 yuan.

[0076] The above is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. It will be apparent to those skilled in the art that various modifications to these embodiments are possible, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but will conform to the widest scope consistent with the principles and novel features applied for by the present application.

Claims

1. A method for preparing a low temperature hot rolled strip steel for forming, the method comprising: The continuous casting billet is heated, and the following heating parameters are controlled: soaking time, tapping temperature and time in the furnace; The heated continuous casting billet is subjected to rough rolling and cooling in sequence to obtain an intermediate billet; The intermediate billet is sequentially subjected to finish rolling, laminar cooling and coiling to obtain the low-temperature hot-rolled steel strip; wherein, double descaling is used before the finish rolling, the cooling water and descaling water between the frames are closed during the finish rolling, and rolling lubricating oil is used to reduce the surface shear texture strength and improve the stamping performance.

2. The method according to claim 1, characterized in that Calculated by mass fraction, the chemical composition of the continuous casting billet includes: C: 0.02% to 0.06%, Si: 0% to 0.03%, Mn: 0.1% to 0.4%, P≤0.015%, S≤0.015%, and matrix element Fe.

3. The method according to claim 1, characterized in that The soaking time is 30 to 50 minutes.

4. The method according to claim 1, characterized in that The steel tapping temperature is 950°C to 1050°C.

5. The method according to claim 1, characterized in that The time in the furnace is 120 min to 300 min.

6. The method according to claim 1, characterized in that The outlet temperature of the rough rolling is 870°C to 900°C.

7. The method according to claim 1, characterized in that The finishing rolling equipment comprises 7 stands F1 to F7, the pass reduction rate of stands F1 to F3 is 30% to 45%, and the pass reduction rate of stand F7 is greater than 15%.

8. The method according to claim 1, characterized in that The concentration of the rolling lubricating oil is 0.3% to 0.6%.

9. The method according to claim 1, characterized in that: The inlet temperature of the finishing rolling is 800°C to 860°C, and the terminal temperature of the finishing rolling is 750°C to 800°C.

10. The method according to claim 1, characterized in that The coiling temperature is 620°C to 700°C.

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