Preparation method of stamping and galling resistant GI coating product

Abstract

The invention relates to a preparation method of a stamping and galling resistant GI coating product, and belongs to the technical field of steel rolling. The method comprises the following steps: carrying out hot galvanizing treatment on strip steel to obtain galvanized strip steel; carrying out aerial fog cooling on the galvanized strip steel so as to form fine and uniform spangles on the surface of the galvanized strip steel; carrying out air cooling on the galvanized strip steel subjected to aerial fog cooling; and the air-cooled galvanized strip steel is subjected to finishing treatment, so that the Rsk value of the surface of the galvanized strip steel is a negative number, and the galvanized plate is obtained. Small-size spangles are obtained on the surface of the galvanized strip steel through aerial fog cooling, and the reduction of the sizes of the spangles is beneficial to improving the surface uniformity of the galvanized strip steel; by controlling the Rsk value of the surface of the roller of the finishing machine to be a positive value, the surface of the galvanized strip steel obtains a negative Rsk value, and therefore it is guaranteed that the surface of the galvanized strip steel has good abrasion resistance; the surface roughness of the obtained galvanized sheet is at a low level, and it is guaranteed that the surface coating of the galvanized sheet has good galling resistance.

Description

Technical Field

[0001] The present application relates to the technical field of steel rolling, and in particular to a method for preparing a GI coating product that is resistant to stamping and roughening. Background Art

[0002] In the sophisticated and evolving industry of automobile manufacturing, stamping parts, as key manufacturing process elements, are used in a wide range of manufacturing fields for body structural parts and covering parts. These stamping parts not only bear the stability and safety of the automobile structure, but also have a profound impact on the appearance and overall performance of the vehicle. However, in recent years, with the continuous innovation of automobile design and the growing demand of consumers for personalized and high-performance automobiles, the shape design of automobile body parts has become increasingly complex, which undoubtedly brings unprecedented challenges to mold design and the design difficulty has risen sharply. At the same time, with the improvement of environmental protection awareness and the improvement of automobile durability requirements, the requirements for corrosion resistance of automobile bodies have also reached new heights. In order to meet this challenge, automobile manufacturers have adopted galvanized products to replace traditional cold-rolled plates as the main material for body parts. With its excellent anti-corrosion performance and good processing performance, galvanized products effectively improve the durability and corrosion resistance of the car body, providing a strong guarantee for the long-term use of the car.

[0003] However, this change also brings new technical challenges. Especially for some deep-drawn parts, the contact force between the die and the strip surface is very large during the stamping process, and there is relative sliding during the drawing process, which can easily lead to surface roughness and zinc powder shedding during the stamping process. The shedding of zinc powder will not only affect the surface quality of the stamped parts, but also cause wear and contamination to the die, thus affecting the production quality of subsequent parts. Summary of the invention

[0004] The present application provides a method for preparing a GI coating product that is resistant to stamping and roughening, in order to solve the following technical problem: how to solve the problem of roughening and zinc powder shedding of existing GI coating products during the stamping process.

[0005] The present application provides a method for preparing a GI coating product that is resistant to stamping and roughening, the method comprising:

[0006] The strip steel is subjected to hot-dip galvanizing treatment to obtain galvanized strip steel;

[0007] The galvanized steel strip is subjected to mist cooling to form fine and uniform zinc flowers on the surface of the galvanized steel strip;

[0008] air cooling the galvanized steel strip after mist cooling;

[0009] The galvanized steel strip after air cooling is subjected to skin finishing treatment so that the Rsk value of the surface of the galvanized steel strip is negative, thereby obtaining a galvanized sheet.

[0010] Optionally, the size of the zinc flower is less than 200 μm.

[0011] Optionally, the size of the zinc flower is less than 100 μm.

[0012] Optionally, the surface roughness of the galvanized sheet is less than 1.0 μm.

[0013] Optionally, the surface roughness of the galvanized sheet is less than 0.8 μm.

[0014] Optionally, the starting temperature of the aerosol cooling is 400°C to 450°C, and the ending temperature of the aerosol cooling is 350°C to 400°C.

[0015] Optionally, the starting temperature of the aerosol cooling is 420°C to 430°C, and the ending temperature of the aerosol cooling is 370°C to 380°C.

[0016] Optionally, the rolling force of the skin-pass treatment is 3000 N / m 2 ~5000N / m 2 .

[0017] Optionally, the air-cooled strip steel passes through a tower top roller, and the temperature of the tower top roller is <230°C.

[0018] Optionally, the surface roughness of the steel strip is 0.8 μm to 1.3 μm.

[0019] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0020] The present application provides a method for preparing a GI coating product that is resistant to stamping and roughening, the method comprising: subjecting a steel strip to hot-dip galvanizing to obtain a galvanized steel strip; subjecting the galvanized steel strip to mist cooling to form fine and uniform zinc flowers on the surface of the galvanized steel strip; subjecting the galvanized steel strip after mist cooling to air cooling; subjecting the galvanized steel strip after air cooling to skin-finishing treatment to make the Rsk value of the surface of the galvanized steel strip negative, thereby obtaining a galvanized sheet. Small-sized zinc flowers are obtained on the surface of the galvanized steel strip by mist cooling, and the reduction in the size of the zinc flowers helps to improve the surface uniformity of the galvanized steel strip; by controlling the Rsk value of the surface of the roller of the skin-finishing mill to be a positive value, the surface of the galvanized steel strip obtains a negative Rsk value, thereby ensuring that the surface of the galvanized steel strip has good wear resistance; the surface roughness of the obtained galvanized sheet is at a relatively low level, ensuring that the surface coating of the galvanized sheet has good anti-roughening ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in 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.

[0023] Figure 1 A schematic flow chart of a method for preparing a GI coating product resistant to stamping and roughening provided in an embodiment of the present application;

[0024] Figure 2 The zinc flower size diagram provided in Example 1 of the present application;

[0025] Figure 3 The zinc flower size diagram provided for comparative example 1 of this application;

[0026] Figure 4 This is a comparison chart of the zinc powder shedding on the coating surface provided in Example 1 of the present application and Comparative Example 1. DETAILED DESCRIPTION

[0027] 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.

[0028] 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.

[0029] 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, parts by mass, etc., indicate the proportional relationship between the components.

[0030] 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.

[0031] GI is the abbreviation of Galvanized Iron, and its Chinese name is galvanized iron. GI coated products, namely hot-dip galvanized steel sheets, are an important steel protective material. GI coated products are made by hot-dip galvanizing technology, where a layer of zinc is plated on the surface of steel. The zinc layer is tightly combined with the steel matrix to form a protective metal composite. This technology uses the activity of zinc to make it react preferentially with oxygen or corrosive media in the environment, thereby protecting the steel matrix from corrosion.

[0032] Figure 1 A schematic flow chart of a method for preparing a GI coating product resistant to stamping and roughening provided in an embodiment of the present application.

[0033] See also Figure 1 The present application provides a method for preparing a GI coating product that is resistant to stamping and roughening, comprising:

[0034] S1, hot-dip galvanizing the strip steel to obtain galvanized strip steel;

[0035] In some embodiments, the surface roughness of the steel strip is 0.8 μm to 1.3 μm.

[0036] The positive effect of limiting the surface roughness of the steel strip to 0.8 μm to 1.3 μm is that this roughness range helps the subsequent processes to proceed smoothly, while ensuring good bonding between the galvanized layer and the steel strip substrate. For example, the surface roughness of the steel strip can be 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, etc.

[0037] S2, performing mist cooling on the galvanized steel strip to form fine and uniform zinc flowers on the surface of the galvanized steel strip;

[0038] Aerosol cooling is an efficient cooling technology. It uses a high-pressure fan to generate wind with a certain pressure, flow rate and flow rate, and water with a certain pressure and flow rate in the water supply pipe (usually the water temperature is below 35°C). When passing through the nozzle at the same time, the water and wind are completely mixed with the jet principle to spray out uniform, diffuse and fine aerosol. This aerosol quickly exchanges heat on the surface of the object being cooled, taking away the heat on the surface of the object, thereby shortening the cooling time of the object and making it reach the temperature required by the process within a certain controllable time range. The key to aerosol cooling is to use airflow to disperse water into droplets and bring it to the surface of the entire object being cooled. Compared with traditional cooling methods, it does not mind forming an airflow film layer, but rather uses the constantly updated airflow film layer to cool the object evenly and quickly. This method can significantly improve cooling efficiency and reduce the waste of water resources.

[0039] In some embodiments, the size of the zinc flowers is less than 200 μm.

[0040] In some embodiments, the size of the zinc flowers is less than 100 μm.

[0041] Mist cooling can quickly reduce the temperature of the strip, while refining the zinc flowers and improving the surface quality of the galvanized sheet. For example, the size of the zinc flowers on the surface of the strip after mist cooling can be 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, etc. Preferably, the size of the zinc flowers is less than 100μm.

[0042] In some embodiments, the starting temperature of the aerosol cooling is 400°C to 450°C, and the ending temperature of the aerosol cooling is 350°C to 400°C.

[0043] In some embodiments, the starting temperature of the aerosol cooling is 420°C to 430°C, and the ending temperature of the aerosol cooling is 370°C to 380°C.

[0044] Mist cooling can quickly reduce the temperature of the strip by mixing fine water droplets and compressed air. Setting the starting temperature at 420℃~430℃ can ensure that the strip still has a high temperature after hot-dip galvanizing, which is conducive to the uniform adhesion and rapid cooling of the zinc layer. Exemplarily, the starting temperature of mist cooling can be 420℃, 422℃, 424℃, 426℃, 428℃, 430℃, etc. At the same time, the setting of the ending temperature of 370℃~380℃ can ensure that the strip will not produce stress or deformation due to too low temperature during the cooling process, thereby maintaining the shape and dimensional stability of the product. Exemplarily, the ending temperature of mist cooling can be 370℃, 372℃, 374℃, 376℃, 378℃, 380℃, etc. In addition, the rapid cooling during the mist cooling process helps to refine the zinc flowers on the surface of the strip. The size of the zinc flowers directly affects the appearance quality and corrosion resistance of the galvanized sheet. Tiny zinc flowers can reduce the retention of moisture and corrosive media on the surface and improve the corrosion resistance of the galvanized layer. By limiting the temperature range of mist cooling, the size of zinc flowers can be effectively controlled to meet the requirements of the product.

[0045] S3, air cooling the galvanized steel strip after mist cooling;

[0046] In some embodiments, the air-cooled steel strip passes through a tower top roller, and the temperature of the tower top roller is less than 230°C.

[0047] The tower top roller is a key component in the galvanizing line production equipment, which is mainly used to support and guide the operation of the strip during the galvanizing process. It ensures that the strip maintains a stable operating state during the high-speed and continuous production process through a specific cooling and lubrication mechanism, thereby improving the quality and production efficiency of the product. In the hot-dip galvanizing process, after the strip is galvanized, the strip is cooled by aerosol cooling, and then air-cooled through the tower top roller. At this time, the cooling system of the tower top roller starts to work, taking away the heat from the surface of the roller body, thereby reducing the temperature of the strip. At the same time, the rotation and guiding function of the tower top roller also contributes to the smooth transmission and shape maintenance of the strip. In the embodiment of the present application, the air-cooled strip passes through the tower top roller, and the temperature of the tower top roller <230°C helps to reduce the adhesion between the strip and the roller surface and avoid the phenomenon of hair pulling. Exemplarily, the temperature of the tower top roller can be 210°C, 212°C, 214°C, 216°C, 218°C, 220°C, 222°C, 224°C, 226°C, 228°C, etc.

[0048] S4. Performing a skin-finishing treatment on the galvanized steel strip after air cooling so that the Rsk value of the surface of the galvanized steel strip is negative, thereby obtaining a galvanized sheet.

[0049] In an embodiment of the present application, the equipment for the skin-finishing treatment is a skin-finishing machine, and the rollers of the skin-finishing machine are textured by electric sparks to ensure that the surface Rsk value of the rollers of the skin-finishing machine is positive.

[0050] The skin pass mill is a key equipment in the hot-dip galvanizing line. The skin pass mill can flatten the concave and convex parts of the strip and significantly improve the straightness and flatness of the galvanized sheet. Through skin pass treatment, the strip can better meet the user's strict requirements for plate shape in subsequent processing. After special treatment, the rollers of the skin pass mill can transfer a certain roughness to the surface of the strip. This change in roughness not only helps to meet the specific needs of different users, but also improves the adhesion between the coating and the strip substrate, thereby improving the quality and durability of the coating.

[0051] Electrical discharge texturing (EDT) is a technology that uses the principle of electrospark machining to form a series of tiny electrolytic pits on the surface of the roll, thereby changing its surface morphology and roughness. This technology is widely used in the texturing of various rolls to improve the quality of rolled products. The working principle of the electrospark texturing technology is to immerse the roll and electrode in an insulating working fluid and apply a pulse voltage of a certain amplitude and frequency to the roll and electrode. When the gap between the two is small to a certain value, the pulse voltage ionizes and breaks down the inter-electrode dielectric to form a discharge channel. At this time, the electrons in the channel rush to the positive electrode at high speed, and the positive ions rush to the negative electrode. The electrical energy is converted into kinetic energy, and the kinetic energy is converted into heat energy through collision. In a very short period of time, the temperature rises rapidly to thousands of degrees Celsius or even higher, causing the working fluid to vaporize and the metal material to melt and vaporize. The molten metal is discharged from the working fluid, thereby forming electrolytic pits on the surface of the roll. On the skin-pass mill, the surface roughness of the roll after electrospark texturing is uniform, which helps to improve the surface quality and performance of the rolled products.

[0052] The Rsk value (roughness skewness) is a parameter used to evaluate the symmetry of the surface profile. A positive Rsk value indicates that the peak of the surface is higher, that is, there are more sharp protrusions on the surface. This usually means that there are large discrete peaks on the surface, and the valley bottom is relatively deep or less. A positive Rsk value indicates that the surface has been subjected to some degree of impact or wear during processing, resulting in protrusions in local areas. A negative Rsk value indicates that the valley bottom of the surface is deeper, that is, there are more concave areas on the surface. This usually means that there are large discrete valleys on the surface, and the peaks are relatively few or flat. A negative Rsk value indicates that the surface has been uniformly worn or treated during processing, resulting in a relatively flat overall surface but with some deeper depressions. An Rsk value close to zero indicates that the surface profile is relatively symmetrical, that is, the distribution of peaks and valleys is relatively uniform. This usually means that the surface has been uniformly treated during processing, and no obvious local protrusions or depressions appear. After skin-finishing treatment, the Rsk value of the surface of the galvanized sheet is negative, which helps to form a uniform tensile texture during stamping and reduce the phenomenon of pulling.

[0053] In an embodiment of the present application, the surface of the roller of the polishing machine after electric spark texturing is chrome-plated to enhance its hardness and wear resistance. Chromium is a metal element with high hardness. Forming a dense chromium layer on the surface of the roller by electroplating can significantly improve the wear resistance and scratch resistance of the roller. The hardness of the chrome-plated layer is usually between HV900-1000, which is much higher than the hardness of ordinary rollers. This allows the chrome-plated roller to maintain a good surface state when subjected to high loads and high-speed operation. On the other hand, the chrome-plated layer not only has high hardness, but also has excellent wear resistance. During the rolling process, the chrome-plated layer can effectively reduce the friction and wear between the roller and the strip, thereby extending the service life of the roller.

[0054] In an embodiment of the present application, the roughness of the roller of the skin pass mill after chrome plating is ≤2.0 μm.

[0055] The positive effect of limiting the roughness of the roller of the skin-pass mill after chrome plating to ≤ 2.0 μm: the fine chrome plating layer helps to form a uniform and fine texture to ensure the surface quality of the galvanized sheet after skin-pass treatment. For example, the roughness of the roller after chrome plating can be 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2.0 μm, etc.

[0056] In some embodiments, the rolling force of the skin pass treatment is 3000 N / m 2 ~5000N / m 2 .

[0057] The rolling force of the skin pass treatment is limited to 3000N / m 2 ~5000N / m 2 Positive effect: During the finishing process, 3000N / m 2 ~5000N / m 2 The rolling force can effectively control the strip shape. By accurately setting the rolling force, it can ensure that the strip is uniformly extended during the rolling process, thereby avoiding problems such as wavy and curved strip shapes. This uniform extension helps to improve the overall quality and appearance of the product. In addition, the rolling force has a significant effect on the roughness and glossiness of the strip surface. At 3000N / m 2 ~5000N / m 2 Under the rolling force of 3000N / m, the surface of the strip can obtain a more delicate and smooth treatment effect, which helps to reduce the minor flaws and unevenness of the surface, and at the same time helps to form a tight and uniform zinc layer, reducing the phenomenon of roughening and zinc powder shedding during the stamping process. For example, the rolling force of the skin-finishing treatment can be 3000N / m 2 、3400N / m 2 、3800N / m2 , 4200N / m 2 、4600N / m 2 、4500N / m 2 wait.

[0058] In some embodiments, the surface roughness of the galvanized sheet is less than 1.0 μm.

[0059] In some embodiments, the surface roughness of the galvanized sheet is less than 0.8 μm.

[0060] The surface roughness of the galvanized sheet is less than 1.0 μm, ensuring good surface quality and corrosion resistance. Exemplarily, the surface roughness of the galvanized sheet can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, etc. Preferably, the surface roughness of the galvanized sheet is less than 0.8 μm.

[0061] In some embodiments, the method provided in the embodiments of the present invention is applicable to hot-dip galvanized automobile sheets with a thickness of less than 1.0 mm.

[0062] The present application is further described below in conjunction with specific embodiments. The experimental methods in the following embodiments that do not specify specific conditions 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.

[0063] Embodiment 1:

[0064] In an embodiment of the present invention, the production of DX54D+Z hot-dip galvanized products with a thickness of 0.7mm and a width of 1300mm is provided: wherein, the skin-pass mill roller (roller diameter is 650mm) is roughened in a positive pulse mode, and after roughening, a super-fine grinding is performed, and after super-fine grinding, the roller surface is chrome-plated. The roller surface roughness is 2.0μm, and then the Rsk value of the roller surface is measured, and its value is 0.21. After the galvanized strip passes through the zinc pot air knife, the galvanized strip is cooled by mist cooling above the air knife. The starting temperature of the cooling is 429°C, and the ending temperature of the cooling is 375°C. The skin-pass mill rollers are put into operation, and hot-dip galvanized strip is produced in the early stage of the rollers. The skin-pass elongation is 0.8%, the skin-pass mill inlet tension is 42KN, the skin-pass mill outlet tension is 48KN, and the skin-pass rolling force is 3868KN. The Rsk value of the surface of the galvanized sheet is -0.82. Through the above measures, such as Figure 2 The size of zinc flowers on the surface of the obtained galvanized sheet is less than 100 μm.

[0065] Embodiment 2:

[0066] In an embodiment of the present invention, the production of DX54D+Z hot-dip galvanized products with a thickness of 0.65 mm and a width of 1500 mm is provided: wherein, the skin-pass mill roll (roller diameter is 650 mm) is roughened in a positive pulse mode, and then a super-fine grinding is performed after roughening, and the roll surface is chrome-plated after super-fine grinding. The roll surface roughness is 2.0 μm, and then the Rsk value of the roll surface is measured, and its value is 0.23. After the galvanized strip passes through the zinc pot air knife, the galvanized strip is cooled by mist cooling above the air knife, and the starting temperature of cooling is 427°C and the ending temperature of cooling is 365°C. The skin-pass mill roll is put into production, and hot-dip galvanized strip is produced in the early stage of the roll. The skin-pass elongation is 0.8%, the skin-pass mill entrance tension is 42KN, the skin-pass mill exit tension is 47KN, and the skin-pass rolling force is 4200KN. The Rsk value of the surface of the galvanized sheet is -0.84. Through the above measures, the size of zinc flowers on the surface of the galvanized sheet is obtained to be less than 150μm.

[0067] Embodiment 3:

[0068] In an embodiment of the present invention, the production of DX54D+Z hot-dip galvanized products with a thickness of 0.65 mm and a width of 1580 mm is provided: wherein, the skin-pass mill roll (roller diameter is 650 mm) is roughened in a positive pulse mode, and after roughening, a super-fine grinding is performed, and after super-fine grinding, the roll surface is chrome-plated. The roll surface roughness is 2.0 μm, and then the Rsk value of the roll surface is measured, and its value is 0.22. After the galvanized strip passes through the zinc pot air knife, the galvanized strip is cooled by mist cooling above the air knife, and the starting temperature of cooling is 429°C and the ending temperature of cooling is 370°C. The skin-pass mill roll is put into production, and hot-dip galvanized strip is produced in the early stage of the roll. The skin-pass elongation is 0.8%, the skin-pass mill entrance tension is 42KN, the skin-pass mill exit tension is 45KN, and the skin-pass rolling force is 4100KN. The Rsk value of the surface of the galvanized sheet is -0.79. Through the above measures, the size of zinc flowers on the surface of the galvanized sheet is obtained to be less than 150μm.

[0069] Comparative Example 1:

[0070] The skin-pass mill roll (roller diameter is 650mm) is roughened in positive pulse mode, the roll surface roughness is 2.6μm, and the roll surface Rsk value is -0.42. After the galvanized strip passes through the zinc pot air knife, a mobile cooling fan is used above the air knife for cooling, and then a fixed cooling fan is used for cooling. The tower top roll temperature is 233°C. The skin-pass mill roll is put into production, and hot-dip galvanized strip is produced in the early stage of the roll. The skin-pass elongation is 1.0%, the skin-pass mill inlet tension is 56KN, and the skin-pass mill outlet tension is 62KN. The skin-pass rolling force is 3220KN, and the Rsk value is -0.12. Through the above measures, such as Figure 3The surface structure data of the galvanized sheets of the embodiment and the comparative example are shown in Table 1.

[0071] In Table 1, "Ra" stands for the Arithmetical Mean Deviation of the Roughness Profile, which is a standard parameter for measuring surface roughness. The Ra value is calculated by measuring the arithmetic mean of the vertical distances of all profile points on the surface (relative to a center line or reference plane). The smaller the value, the smoother the surface; conversely, the larger the Ra value, the rougher the surface.

[0072] Table 1 Surface structure data of galvanized sheet of embodiment and comparative example

[0073] Group Rsk Ra Example 1 -0.82 0.83 Example 2 -0.84 0.95 Example 3 -0.79 0.92 Comparative Example 1 -0.12 1.1

[0074] It can be seen from Table 1 that the preparation process parameters of the embodiments are all within the required range of the present invention, and the surface roughness of the galvanized sheet is relatively small, which can ensure that the surface coating has good anti-picking ability.

[0075] Attached Figure 4 Detailed description:

[0076] Figure 4 The following is a comparison chart of the zinc powder shedding on the coating surface provided in Example 1 of the present application and Comparative Example 1, as shown in FIG. Figure 4 As shown, the zinc powder shedding condition on the coating surface in Example 1 is significantly improved.

[0077] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0078] The GI coating product prepared by the method provided by the embodiment of the present invention not only has excellent corrosion resistance, but also has good stamping formability and surface quality, and is suitable for various industrial application fields with strict requirements.

[0079] The preparation method provided by the embodiment of the present invention has stable process and strong controllability, which is conducive to large-scale production and quality control.

[0080] The above description 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 the embodiments shown in the present application, but will conform to the widest range consistent with the principles and novel features applied for by the present application.

Claims

1. A method for preparing a GI coating product resistant to stamping and roughening, the method comprising: The strip steel is subjected to hot-dip galvanizing treatment to obtain galvanized strip steel; The galvanized steel strip is subjected to mist cooling to form fine and uniform zinc flowers on the surface of the galvanized steel strip; air cooling the galvanized steel strip after mist cooling; The galvanized steel strip after air cooling is subjected to skin finishing treatment so that the Rsk value of the surface of the galvanized steel strip is negative, thereby obtaining a galvanized sheet.

2. The method according to claim 1, characterized in that The size of the zinc flower is less than 200 μm.

3. The method according to claim 2, characterized in that The size of the zinc flower is less than 100 μm.

4. The method according to claim 1, characterized in that: The surface roughness of the galvanized sheet is less than 1.0 μm.

5. The method according to claim 4, characterized in that The surface roughness of the galvanized sheet is less than 0.8 μm.

6. The method according to claim 1, characterized in that The starting temperature of the aerosol cooling is 400°C to 450°C, and the ending temperature of the aerosol cooling is 350°C to 400°C.

7. The method according to claim 6, characterized in that The starting temperature of the aerosol cooling is 420°C to 430°C, and the ending temperature of the aerosol cooling is 370°C to 380°C.

8. The method according to claim 1, characterized in that: The rolling force of the skin-pass treatment is 3000 N / m 2 ~5000N / m 2 .

9. The method according to claim 1, characterized in that: The air-cooled galvanized steel strip passes through a tower top roller, and the temperature of the tower top roller is less than 230°C.

10. The method according to claim 1, characterized in that The surface roughness of the strip steel is 0.8 μm to 1.3 μm.

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