Steel plate having pattern on surface, and manufacturing method therefor

Abstract

A steel plate having a pattern on the surface, and a manufacturing method for the steel plate. At least one side surface of the steel plate has two or more regions having different average surface roughness. The surface of the steel plate has a pattern formed by a visual color difference generated by the difference of different average surface roughness.

Description

Steel plate with pattern on surface and manufacturing method thereof Technical Field

[0001] The present invention relates to the field of steel plates, and in particular to a steel plate with a pattern on the surface and a manufacturing method thereof. Background Art

[0002] As users' requirements for product surface appearance increase and personalized needs continue to emerge, there is a demand for printing patterns or designs on the surface of steel plates.

[0003] Although the need to form patterns, designs or trademarks on the surface of steel plates can be achieved through existing technologies such as chemical etching, electroplating, printing, laser marking, mechanical embossing, etc., the preparation of patterns or designs requires additional processing steps, and some of these technologies also require the use of additional consumables, so the processing cost is relatively high.

[0004] In addition, etching, electroplating, etc. often require the use of chemical reagents, which poses certain environmental risks; spray printing on the surface of steel plates usually destroys the original metallic color of the steel plate surface due to the presence of non-metallic inks or coatings; the processing efficiency of laser marking is relatively low; although mechanical stamping is relatively low in cost, it will cause plastic deformation of the material during the mechanical stamping process, increase the yield strength of the material, and increase the yield-to-strength ratio, which will greatly reduce the stamping performance of the material.

[0005] For example, the Chinese patent document with publication number CN101077676B, publication date September 21, 2011, and titled "A printed metal plate capable of being processed by sheet metal and a method for manufacturing the same" discloses a printed metal plate capable of being processed by sheet metal and a method for manufacturing the same. The method requires the use of paint transfer to print patterns on the surface of the steel plate, which is costly and also requires curing treatment.

[0006] For example, a Chinese patent document with publication number CN104368660B and publication date February 10, 2016, entitled “A continuous galvanized flat embossing process” discloses a continuous galvanized flat embossing process, which uses an engraved roller in a hot-dip galvanizing flattening process to obtain a hot-dip galvanized steel plate with an embossed surface. Since the pattern on the steel plate surface is imprinted by the engraved roller, and the engraved roller requires special equipment for processing, the cost is relatively high, and the pattern effect is based on the concave and convex three-dimensional sense of the surface contour. This surface concave and convex texture will be significantly damaged during stamping due to the plastic deformation of the material. Summary of the Invention

[0007] One of the purposes of the present invention is to provide a steel plate with a pattern on the surface. No additional chemical reagents are used during the processing of the steel plate. The surface pattern effect is achieved by the visual color difference caused by the difference in surface roughness of different areas on the surface of the steel plate, so the mechanical properties of the material will not be reduced.

[0008] In order to achieve the above-mentioned objectives, the present invention provides a steel plate with a pattern on the surface, wherein at least one side of the surface of the steel plate has two or more areas with different average surface roughness, and the surface of the steel plate has a pattern formed by the visual color difference caused by the difference in different average surface roughness.

[0009] In some embodiments, the steel plate is composed of a steel substrate. Since no additional chemical reagents are used in the process of processing the surface of the steel substrate to form the pattern, the surface of the steel plate still retains the metallic luster of the steel substrate itself after the surface pattern is formed, and the mechanical properties of the steel plate are not reduced.

[0010] Preferably, the average surface roughness difference ΔSa between two adjacent areas with different average surface roughness on the same side surface of the steel plate is 板S ≥0.4μm, preferably ΔSa 板S ≥0.8μm. ΔSa 板S There is no particular upper limit on ΔSa, and those skilled in the art can determine it based on the color difference contrast requirements of the target pattern, but it is preferably 板S ≤2.0μm.

[0011] Preferably, any one or more of the two or more regions with different average surface roughness is discontinuous and divided into two or more sub-regions, and the average surface roughness difference ΔSa between a sub-region in one region and an adjacent region or sub-region with different average surface roughness on the same side surface of the steel plate is 板S ≥0.4μm, preferably ΔSa 板S ≥0.8μm. ΔSa 板 S There is no particular upper limit on ΔSa, and those skilled in the art can determine it based on the color difference contrast requirements of the target pattern, but it is preferably 板S ≤2.0μm.

[0012] Preferably, the average surface roughness Sa of the region with the lowest roughness among the two or more regions with different average surface roughness is min ≤1.2μm, preferably Sa min ≤1.0μm.

[0013] Preferably, there is a transition zone with a width of ≤0.1 mm between two adjacent areas with different average surface roughness on the same side surface of the steel plate, and the difference ΔSa′ between the average surface roughness of the transition zone and the average surface roughness of any one of the two adjacent areas with different average surface roughness is S Less than the average surface roughness difference ΔSa between the two adjacent regions with different average surface roughness 板S ; Preferably, the width of the transition zone is 0.05 to 0.1 mm.

[0014] Preferably, the steel substrate contains, in addition to Fe and unavoidable impurities, the following chemical elements in percentage by mass:

[0015] 0<C≤0.1%,0<Si≤0.02%,0<Mn≤0.5%,P≤0.035%,S≤0.035%,N≤0.01%. Preferably, the steel substrate contains the following chemical elements by mass percentage:

[0016] 0<C≤0.1%, 0<Si≤0.02%, 0<Mn≤0.5%, P≤0.035%, S≤0.035%, N≤0.01%, and the balance is Fe and unavoidable impurities.

[0017] Preferably, the yield strength of the steel plate is ≤240MPa; the tensile strength is ≥270MPa, preferably ≥329MPa; the yield strength ratio is ≤0.7; the elongation after fracture A 80 ≥30%; and / or the thickness of the steel plate is 0.4 to 2.0 mm, preferably 0.7 to 1.2 mm.

[0018] The present invention also provides a method for manufacturing the above-mentioned steel plate with a pattern on the surface, which comprises the following steps performed in sequence:

[0019] 1) cold rolling the hot-rolled steel plate, and controlling the average surface roughness Sa of the steel plate after cold rolling to be ≤1.2 μm;

[0020] 2) Annealing the cold-rolled steel sheet;

[0021] 3) Smoothing the annealed steel plate with a patterned roller to obtain a steel plate with a patterned surface, wherein the surface of the patterned roller has two or more regions with different average surface roughness.

[0022] In this method, the surface roughness of the steel sheet after cold rolling can be controlled by controlling the roughness of the rolls used in the cold rolling process (the above step 1). Although the average surface roughness difference ΔSa between two adjacent areas with different average surface roughness on the same side surface of the steel sheet produced by this method is controlled, 板S≥0.4μm can achieve the desired pattern, but the average surface roughness of the steel plate after cold rolling is too high will also weaken the pattern effect of the surface of the obtained steel plate. Therefore, in order to further improve the clarity of the pattern on the surface of the steel plate, the surface roughness Sa of the steel plate after cold rolling can be controlled to be ≤1.2μm. Preferably, the surface roughness Sa of the steel plate after cold rolling can be controlled to be ≤1.0μm, so that the average surface roughness Sa of the lowest area among the two or more areas with different average surface roughness on at least one side of the surface of the steel plate obtained by this method is min ≤1.2μm, preferably Sa min ≤1.0μm.

[0023] Preferably, the method satisfies at least one of the following conditions:

[0024] The average surface roughness difference ΔSa between two adjacent areas with different average surface roughness in the pattern roller 辊

[0025] S ≥1.5μm, preferably ΔSa 辊S 1.5 to 2.8 μm;

[0026] In step 3), the leveling rate is 1 to 3%, preferably 2 to 3%;

[0027] In step 3), the pattern on the surface of the patterned roller is produced by laser texturing. Preferably,

[0028] When laser texturing the pattern roller, the following relationship is satisfied:

[0029] Wherein, Ф represents the diameter of the pattern roller, in mm; v represents the rotation speed of the pattern roller, in r / min; f represents the laser switching frequency, in Hz.

[0030] By controlling the diameter of the pattern roller, the rotation speed of the pattern roller and the switching frequency of the laser, the width of the transition zone can be controlled within 0.1mm, making the pattern on the surface of the steel plate clearer.

[0031] Preferably, Φ is 475 to 481 mm, v is 120 to 180 r / min, and f is 80,000 to 85,000.

[0032] In this method, when the flatness is lower than 1%, due to the small flattening reduction, the contact pressure between the roller and the strip surface is insufficient, and the roller surface pattern is difficult to be effectively transferred to the strip surface; when the flatness is higher than 3%, due to the excessive flattening reduction, the yield strength of the steel plate increases significantly, the material yield strength ratio is too high, and the stamping performance of the material is affected. The flatness can be controlled to be 1 to 3% (preferably 2 to 3%) and / or the average surface roughness difference ΔSa of two adjacent areas with different average surface roughness in the pattern roller 辊L ≥1.5μm (preferably ΔSa 辊L 1.5 to 2.8 μm), thereby ensuring that the average surface roughness difference ΔSa between two adjacent areas with different average surface roughness on the same side surface of the steel plate produced by this method is 板 S ≥0.4μm.

[0033] In this method, the power of the laser can be dynamically adjusted according to the shape of the target pattern, and areas with different roughness can be processed on the roller surface.

[0034] In certain embodiments, the steel plate includes a steel substrate and a zinc-aluminum-magnesium coating coated on a surface of the steel substrate, and the surface of the steel plate having the pattern is the outer surface of the zinc-aluminum-magnesium coating.

[0035] Preferably, the average surface roughness difference ΔSa between two adjacent areas with different average surface roughness on the same side outer surface of the zinc-aluminum-magnesium coating is 板L ≥0.4μm, preferably ΔSa 板L ≥0.8μm. ΔSa 板L There is no particular upper limit on ΔSa, and those skilled in the art can determine it based on the color difference contrast requirements of the target pattern, but it is preferably 板L ≤2.0μm.

[0036] Preferably, any one or more of the two or more regions with different average surface roughness is discontinuous and divided into two or more sub-regions, and the average surface roughness difference ΔSa between a sub-region in one region and an adjacent region or sub-region with different average surface roughness on the same side outer surface of the zinc-aluminum-magnesium coating is 板L ≥0.4μm, preferably ΔSa 板L ≥0.8μm. ΔSa 板L There is no particular upper limit on ΔSa, and those skilled in the art can determine it based on the color difference contrast requirements of the target pattern, but it is preferably 板L ≤2.0μm.

[0037] Preferably, there is a transition zone with a width of ≤0.1 mm between two adjacent areas with different average surface roughness on the outer surface of the same side of the zinc-aluminum-magnesium coating, and the difference ΔSa′ between the average surface roughness of the transition zone and the average surface roughness of any one of the two adjacent areas with different average surface roughness is L Less than the average surface roughness difference ΔSa between two adjacent areas with different average surface roughness 板L ; Preferably, the width of the transition zone is 0.04 to 0.07 mm.

[0038] Preferably, the steel substrate contains, in addition to Fe and unavoidable impurities, the following chemical elements in percentage by mass:

[0039] 0<C≤0.1%, 0<Si≤0.02%, 0<Mn≤0.5%, P≤0.035%, S≤0.025%, N≤0.01%.

[0040] Preferably, the steel substrate contains the following chemical elements by mass percentage:

[0041] 0<C≤0.1%, 0<Si≤0.02%, 0<Mn≤0.5%, P≤0.035%, S≤0.025%, N≤0.01%, and the balance is Fe and unavoidable impurities.

[0042] Preferably, the yield strength of the steel plate is ≤240MPa; the tensile strength is ≥270MPa, preferably ≥329MPa; the yield strength ratio is ≤0.7; the elongation after fracture A 80 ≥30%; and / or the thickness of the steel plate is 0.4 to 2.0 mm, preferably 0.8 to 1.6 mm.

[0043] Preferably, the zinc-aluminum-magnesium coating contains, in addition to Zn and unavoidable impurities, the following chemical elements in percentage by mass: Al: 1-15%, Mg: 0.1-5%.

[0044] Preferably, the zinc-aluminum-magnesium coating contains the following chemical elements in mass percentage: Al: 1-15%, Mg: 0.1-5%, and the balance is Zn and unavoidable impurities.

[0045] The present invention also provides a method for manufacturing the above-mentioned steel plate with a pattern on the surface, wherein the steel plate has a zinc-aluminum-magnesium coating, and the method comprises the following steps performed in sequence:

[0046] a) annealing the cold-rolled steel sheet;

[0047] b) hot-dip coating the annealed steel sheet to obtain a steel sheet having a zinc-aluminum-magnesium coating;

[0048] c) using a patterned roller to smooth the steel plate having the zinc-aluminum-magnesium coating to obtain a steel plate having a patterned surface, wherein the surface of the patterned roller has two or more regions with different average surface roughness.

[0049] In this method, since the pattern is generated on the surface of the zinc-aluminum-magnesium coating, there is no particular requirement for the surface roughness of the cold-rolled steel sheet.

[0050] Preferably, the method satisfies at least one of the following conditions:

[0051] The average surface roughness difference ΔSa between two adjacent areas with different average surface roughness in the pattern roller 辊 L ≥1.5μm, preferably ΔSa 辊L 1.5 to 2.8 μm;

[0052] In step c), the leveling rate is 1 to 3%, preferably 2 to 3%;

[0053] In step c), the pattern on the surface of the patterned roller is produced by laser texturing; preferably,

[0054] When laser texturing the pattern roller, the following relationship is satisfied:

[0055] Wherein, Ф represents the diameter of the pattern roller, in mm; v represents the rotation speed of the pattern roller, in r / min; f represents the laser switching frequency, in Hz.

[0056] By controlling the diameter of the pattern roller, the rotation speed of the pattern roller and the switching frequency of the laser, the width of the transition zone can be controlled within 0.1mm, making the pattern on the surface of the steel plate clearer.

[0057] Preferably, Φ is 475 to 481 mm, v is 120 to 181 r / min, and f is 65,000 to 85,000.

[0058] In this method, when the flatness is lower than 1%, due to the small flattening reduction, the contact pressure between the roller and the strip surface is insufficient, and the roller surface pattern is difficult to be effectively transferred to the strip surface; when the flatness is higher than 3%, due to the excessive flattening reduction, the yield strength of the steel plate increases significantly, the material yield strength ratio is too high, and the stamping performance of the material is affected. The flatness can be controlled to be 1 to 3% (preferably 2 to 3%) and / or the average surface roughness difference ΔSa of two adjacent areas with different average surface roughness in the pattern roller 辊L ≥1.5μm (preferably ΔSa 辊L1.5 to 2.8 μm), thereby ensuring that the average surface roughness difference ΔSa between two adjacent areas with different average surface roughness on the same side surface of the zinc-aluminum-magnesium coating of the steel sheet produced by this method is 板S ≥0.4μm.

[0059] In this method, the power of the laser can be dynamically adjusted according to the shape of the target pattern, and areas with different roughness can be processed on the roller surface.

[0060] The method of manufacturing a steel plate with a pattern on the surface of the present invention does not require additional processing steps and additional chemical reagents. Instead, the pattern is directly processed on the surface of the steel plate through the leveling step in the conventional steel plate production process, so that the patterned steel plate can maintain mechanical properties basically consistent with those of conventional steel plates.

[0061] As used herein, the term "steel substrate" refers to any suitable steel sheet without a coating, such as a steel sheet composed of cold-rolled steel.

[0062] In this article, the term "surface roughness" refers to surface roughness measured according to ISO 25178-2:2021. The average surface roughness is obtained by measuring the surface roughness of the same area three or more times and taking the average value.

[0063] In this document, the term "regions with different average surface roughness" refers to multiple regions on the surface of a patterned roller or a steel plate (with or without a zinc-aluminum-magnesium coating), and these regions on the same surface have "average surface roughness" that is different from each other as measured in the above manner. For a patterned roller, the "regions with different average surface roughness" can be produced by a laser texturing process; for a steel plate (with or without a zinc-aluminum-magnesium coating), the "regions with different average surface roughness" are produced by the leveling step of the method of the present invention. A steel plate (with or without a zinc-aluminum-magnesium coating) can have two "regions with different average surface roughness", for example, as shown in FIG3 , the average surface roughness Sa of the low roughness area B is 0.0447 W / m2. l =0.64μm, average surface roughness Sa of high roughness area A h=1.45μm, then the low roughness area B and the high roughness area A are two "areas with different average surface roughness"; similarly, the low roughness area B1 and the high roughness area A1 shown in Figure 4 are also two "areas with different average surface roughness". In some other cases, the steel plate (with or without zinc-aluminum-magnesium coating) can also have more than two (for example, three, four, five or six) "areas with different average surface roughness" to meet the diversified pattern design requirements. Preferably, any one or more of the "two or more areas with different average surface roughness" can be discontinuous, for example, divided into multiple sub-areas, such as the area B shown in Figure 2 is composed of multiple sub-areas. Those skilled in the art can routinely adjust the position, shape and arrangement of the "two or more areas with different average surface roughness" on the surface of the steel plate according to the shape of the target pattern.

[0064] In this article, the term "transition zone" refers to an area where two adjacent areas have different average surface roughness (for example, the average surface roughness difference ΔSa is ΔSa). 板S or ΔSa 板L ≥0.4 μm), and the difference ΔSa′ between its average surface roughness and the average surface roughness of any one of the two adjacent regions with different average surface roughnesses s (or ΔSa′ L ) is less than the average surface roughness difference ΔSa between the two adjacent regions with different average surface roughnesses 板s (or ΔSa 板L The term “width of the transition zone” refers to the area between two adjacent areas with different average surface roughness (average surface roughness difference ΔSa 板S or ΔSa 板L ≥0.4μm) (for example, as shown in d in Figure 3 or Figure 4). That is to say, the term "regions with different average surface roughness" defined in this article does not include a "transition zone". The "width of the transition zone" can be determined as follows: along the direction perpendicular to the adjacent boundary of two adjacent regions with different average surface roughness (region A and region B as shown in Figure 3), the average surface roughness of different positions from region A to region B is continuously measured with an equidistant step of 0.001-0.01mm, wherein the shortest distance d between the two farthest positions except for the positions representing the average surface roughness of region A and region B (i.e., several positions at the start and end) is the width of the transition zone. The difference in average surface roughness ΔSa between the two farthest positions is TS (or ΔSa TL ) is the average surface roughness difference ΔSa between area A and area B 板S (or ΔSa 板L ) more than 90%.

[0065] In this article, the expression "at least one side surface of the steel plate has two or more regions with different average surface roughness" means that any one side surface of the steel plate has two or more regions with different average surface roughness (i.e., only one side surface has a pattern and the other side does not have a pattern), or both sides of the steel plate have two or more regions with different average surface roughness (i.e., both sides have a pattern).

[0066] The "laser texturing process" used in the method of the present invention can be, for example, a method using a roller surface texturing laser processing system disclosed in Chinese patent CN1151907C. Based on this technology, a specific pattern or design can be obtained by controlling the distribution of the texturing point array on the roller surface or adjusting the texturing processing power in different areas.

[0067] Compared with the prior art, the steel plate with a patterned surface and the manufacturing method thereof of the present invention have the following advantages and beneficial effects:

[0068] The surface pattern of the steel plate with a pattern on the surface of the present invention is achieved by the visual color difference effect caused by the difference in surface roughness, which retains the good metallic luster effect of the metal surface itself. In addition, the manufacturing process of the steel plate with a pattern on the surface of the present invention is consistent with that of conventional steel plates, and does not require additional processing steps and additional chemical reagents. Therefore, it has the advantages of low cost and environmental protection. In addition, the pattern is directly imparted by the leveling process in the conventional manufacturing process of the steel plate, so that the steel plate can maintain mechanical properties that are basically consistent with those of conventional steel plates. For example, the yield strength of the steel plate with a pattern on the surface of the present invention is ≤240MPa, the tensile strength is ≥270MPa, the yield strength ratio is ≤0.7, and the elongation after fracture A80 is ≥30%. At the same time, the lower leveling reduction rate also allows the steel plate to maintain good stamping forming performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] FIG1 is a schematic diagram of an exemplary surface morphology cross-sectional profile of a steel plate with a patterned surface according to the present invention.

[0070] FIG. 2 is a schematic diagram showing an exemplary surface pattern effect of a steel plate with a pattern on its surface according to the present invention.

[0071] FIG3 shows the surface microstructure of the steel plate with a pattern on the surface according to Example 1 of the present invention.

[0072] FIG4 shows the surface microstructure of the steel plate with a pattern on the surface according to Example 5 of the present invention. DETAILED DESCRIPTION

[0073] The steel plate with a patterned surface and the manufacturing method thereof according to the present invention will be further explained and illustrated below in conjunction with specific embodiments. However, such explanation and illustration do not constitute an undue limitation to the technical solution of the present invention.

[0074] The surface texture, average surface roughness and mechanical properties of the steel plate of the present invention are measured by the following methods.

[0075] Steel plate surface pattern: The microscopic morphology of the steel plate surface pattern was observed by optical microscope (such as shown in Figures 3 and 4); the clarity of the steel plate surface pattern was observed by visual observation.

[0076] Average surface roughness: The surface roughness of different areas was measured according to ISO 25178-2:2021. Each area was measured at least three times. The average of the surface roughness values ​​measured multiple times was taken to obtain the average surface roughness.

[0077] Mechanical properties of steel plates: measured according to GB / T228.1-2021 standard using a metal material tensile testing machine.

[0078] As shown in FIG1 , the surface pattern of the patterned steel plate of the present invention is formed by at least two regions with different roughness, for example, a high roughness region A with larger micro-profile fluctuations and a low roughness region B with smaller micro-profile fluctuations.

[0079] By controlling different areas to have different roughness, a pattern can be formed on the steel plate surface to achieve a visual color difference effect caused by the surface roughness difference. For example, Figure 2 exemplarily shows an exemplary surface pattern effect of a steel plate with a pattern on the surface of the present invention.

[0080] As shown in FIG2 , a high-roughness region A and a low-roughness region B are formed by controlling the roughness of region A and region B to have different roughnesses, thereby forming a cross pattern on the surface of the steel plate.

[0081] The present invention is further described below using Examples 1-9, and the implementation effect of this case is further verified.

[0082] Examples 1-4

[0083] The steel plates with patterns on the surfaces of Examples 1-4 of the present invention were all prepared by the following steps:

[0084] (1) The hot-rolled steel plate is pickled to remove iron oxide scale, and then cold-rolled. The cold rolling can be carried out by a 5-stand continuous rolling method, and the average surface roughness Sa of the steel plate after cold rolling is controlled to be ≤1.2μm. The mass percentage of each chemical element of the steel plate is shown in Table 1, and the thickness of the steel plate can be 0.4-2.0mm;

[0085] (2) Annealing the cold-rolled steel plate at a temperature of 750-850°C;

[0086] (3) The annealed steel plate is flattened using a patterned roller. The flattening rate can be controlled between 1% and 3%. The patterned roller has areas with different average surface roughness. The specific process parameters are shown in Table 2.

[0087] In the above steps, the roller with a patterned surface is obtained by laser texturing the roller. The laser pulse is turned on and off according to the target pattern shape to achieve selective texturing of the roller surface, resulting in the roller surface having both textured and untextured areas. The surface roughness of the textured and untextured areas is measured according to ISO 25178-2:2021. Each area is measured at least three times to reduce single measurement errors. The average surface roughness is calculated as the average of these measured surface roughness values.

[0088] When laser texturing the roller, the roller diameter Ф (in mm), the laser pulse switching frequency f (in Hz), and the roller speed v (r / min) can be controlled to satisfy the following relationship:

[0089] The above relationship can be satisfied so that the width of the transition zone is ≤ 0.1 mm, where the transition zone is defined as being located between two adjacent regions with different average surface roughnesses, and the difference between its average surface roughness and the average surface roughness of either of the two adjacent regions is ΔSa′ S Less than the average surface roughness difference ΔSa between the two adjacent regions with different average surface roughness 板S area.

[0090] Table 1: Chemical element composition of the steel plates with patterned surfaces of Examples 1-4 (wt%), the remainder being Fe and other unavoidable impurities except P, S, and N.

[0091] Table 2: Process parameters of the steel plates with patterned surfaces of Examples 1-4.

[0092] The surface morphology of the steel plate with a pattern obtained in Example 1 was observed, and FIG3 shows the observation results.

[0093] As shown in Figure 3, the average surface roughness Sa of the low roughness area B is l =0.64μm, average surface roughness Sa of high roughness area A h =1.45μm, difference ΔSa 板S =0.81μm, and the transition zone width d=0.05mm. It can be seen that the adjacent areas A and B have different roughness, thereby forming a pattern on the surface of the steel plate.

[0094] The steel plates with patterned surfaces obtained in Examples 1-4 were sampled respectively, and the mechanical properties of the steel plates with patterned surfaces of each example were tested according to GB / T 228.1-2021. The test results are shown in Table 3. The pattern effect on the surface of the steel plates was also visually evaluated, and the evaluation results are shown in Table 3.

[0095] Table 3. Note: A single “+” in Table 3 indicates that the pattern on the surface of the steel plate is clearly visible under visual observation, which meets the purpose of the present invention; a greater number of “+”s indicates higher clarity or recognition.

[0096] Combining Table 1, Table 2 and Table 3, it can be seen that the steel plates with patterns on the surface of Examples 1-4 of the present invention have clear visible patterns on the surface and also have excellent mechanical properties. The yield strength is less than 240 MPa, the tensile strength is greater than 270 MPa, the yield strength ratio is less than or equal to 0.7, and the elongation after fracture A is less than 0. 80 In terms of manufacturing process, increasing the flattening reduction rate and the difference in the roughness of the roller surface can effectively enhance the clarity of the pattern. For steel plates, the ΔSa of the steel plate surface is 板S It is the ΔSa from the roller surface during the steel plate leveling process. 辊S Therefore, the greater the flattening reduction rate, the higher the replication ratio, and the ΔSa of the steel plate surface 板S On the other hand, at the same leveling reduction rate, the ΔSa of the roll 辊S The larger the value, the greater the ΔSa of the steel plate surface. 板S Therefore, increasing the leveling reduction rate or the ΔSa value of the roll surface is beneficial to increasing the ΔSa value of the steel plate surface and making the pattern clearer.

[0097] Examples 5-9

[0098] The zinc-aluminum-magnesium coated steel sheets with patterns on the surfaces of Examples 5-9 of the present invention were all prepared by the following steps:

[0099] (1) Annealing the cold-rolled steel substrate at a soaking temperature of 730-830° C. The mass percentages of the chemical elements of the cold-rolled steel substrate are shown in Table 1, and the thickness of the steel substrate may be 0.4-2.0 mm.

[0100] (2) The annealed steel substrate is placed in a zinc-aluminum-magnesium plating solution for hot dip plating, and excess plating solution is scraped off with an air knife to form a zinc-aluminum-magnesium coating on the surface of the steel substrate, thereby obtaining a steel plate having a zinc-aluminum-magnesium coating. The mass percentages of the chemical elements in the zinc-aluminum-magnesium coating are shown in Table 5.

[0101] (3) Using a patterned roller to smooth the zinc-aluminum-magnesium coated steel sheet, the smoothing rate is controlled between 1-3%, and a zinc-aluminum-magnesium coated steel sheet with a patterned surface is obtained. Specific process parameters are shown in Table 3.

[0102] In the above steps, the roller with a patterned surface is obtained by laser texturing the roller. The laser pulse is turned on and off according to the target pattern shape to achieve selective texturing of the roller surface, resulting in the roller surface having both textured and untextured areas. The surface roughness of the textured and untextured areas is measured according to ISO 25178-2:2021.

[0103] When laser texturing the roller, the roller diameter Ф (in mm), the laser pulse switching frequency f (in Hz), and the roller speed v (in r / min) can be controlled to satisfy the following relationship:

[0104] The above relationship can be satisfied so that the width of the transition zone is ≤ 0.1 mm, where the transition zone is defined as being located between two adjacent regions with different average surface roughnesses, and the difference between its average surface roughness and the average surface roughness of either of the two adjacent regions is ΔSa′ L Less than the average surface roughness difference ΔSa between the two adjacent regions with different average surface roughness 板L area.

[0105] The mass percentages of the chemical elements in the steel substrates of the steel plates of Examples 5 to 9 of the present invention prepared through the above steps are shown in Table 4.

[0106] Table 4: Mass percentage of each chemical element in the steel substrates of Examples 5-9 (wt%, the balance being Fe and other inevitable impurities except P, S, and N)

[0107] Table 5: Mass percentage of each chemical element in the zinc-aluminum-magnesium coating of the steel sheets of Examples 5-9 (wt%), the balance being Zn and unavoidable impurities

[0108] Table 6: Process parameters for machining surface patterns of Examples 5-9.

[0109] The surface morphology of the patterned zinc-aluminum-magnesium coated steel sheet obtained in Example 5 was observed, and FIG4 shows the observation results.

[0110] As shown in FIG4 , the average surface roughness Sa of the low roughness area B1 is l =0.64μm, average surface roughness Sa of high roughness area A1 h=1.45μm, difference ΔSa 板L =0.81 μm, and the width of the transition zone d=0.05 mm. It can be seen that the adjacent areas A1 and B1 have different roughnesses, thereby forming a pattern on the surface of the zinc-aluminum-magnesium coated steel plate.

[0111] The steel plates with zinc-aluminum-magnesium coatings obtained in Examples 5-9 were sampled respectively, and the mechanical properties of the steel plates of each example were tested according to GB / T 228.1-2021. The test results are shown in Table 7. The pattern effect on the surface of the steel plates was also visually evaluated, and the evaluation results are shown in Table 7.

[0112] Table 7. Note: A single “+” in Table 7 indicates that the pattern on the surface of the zinc-aluminum-magnesium coating is clearly visible under visual observation, which meets the purpose of the present invention; a greater number of “+”s indicates higher clarity or recognition.

[0113] Combining Tables 4 to 7, it can be seen that the steel plates with zinc-aluminum-magnesium coatings of Examples 5-9 have clear visible patterns on the surface and also have excellent mechanical properties. The yield strength is less than 240 MPa, the tensile strength is greater than 270 MPa, the yield strength ratio is less than or equal to 0.7, and the elongation after fracture A is less than 0. 80 In terms of manufacturing process, increasing the flattening reduction rate and the difference in the roughness of the roller surface can effectively enhance the clarity of the pattern. For coated steel plates, the ΔSa of the coating surface 板L It is the ΔSa from the roller surface during the steel plate leveling process. 辊L Therefore, the greater the flattening reduction rate, the higher the replication ratio, and the ΔSa of the coating surface 板L On the other hand, at the same leveling reduction rate, the ΔSa of the roll 辊L The larger the value, the greater the ΔSa of the coating surface. 板L Therefore, increasing the leveling reduction rate or the ΔSa value of the roller surface is beneficial to increasing the ΔSa value of the steel plate coating surface, making the pattern clearer.

[0114] It should be noted that the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features recorded in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0115] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therefrom that can be directly derived from or easily conceived by those skilled in the art based on the disclosure of the present invention are intended to fall within the scope of protection of the present invention.

Claims

1. A steel plate with a pattern on the surface, wherein at least one side of the surface of the steel plate has two or more areas with different average surface roughness, and the surface of the steel plate has a pattern formed by visual color difference caused by the difference in different average surface roughness.

2. The steel plate according to claim 1, wherein: The steel plate is composed of a steel base plate.

3. The steel plate according to claim 2, wherein: The average surface roughness difference ΔSa between two adjacent areas with different average surface roughness on the same side surface of the steel plate 板S ≥0.4μm, preferably ΔSa 板S ≥0.8μm.

4. The steel plate according to claim 2, wherein: Any one or more of the two or more regions with different average surface roughness is discontinuous and divided into two or more sub-regions, and the average surface roughness difference ΔSa between the sub-region in one region and the adjacent region or sub-region with different average surface roughness on the same side surface of the steel plate 板S ≥0.4μm, preferably ΔSa 板S ≥0.8μm.

5. The steel plate according to any one of claims 2 to 4, wherein: The average surface roughness Sa of the region with the lowest roughness among the two or more regions with different average surface roughnesses is min ≤1.2μm, preferably Sa min ≤1.0μm.

6. The steel plate according to any one of claims 2 to 5, wherein: There is a transition zone with a width of ≤0.1 mm between two adjacent regions with different average surface roughness on the same side surface of the steel plate, and the difference ΔSa′ between the average surface roughness of the transition zone and the average surface roughness of any one of the two adjacent regions with different average surface roughness S Less than the average surface roughness difference ΔSa between the two adjacent regions with different average surface roughnesses 板 S ; Preferably, the width of the transition zone is 0.05 to 0.1 mm.

7. The steel plate according to any one of claims 2 to 6, wherein: The steel substrate contains, in addition to Fe and inevitable impurities, the following chemical elements in terms of mass percentage: 0<C≤0.1%, 0<Si≤0.02%, 0<Mn≤0.5%, P≤0.035%, S≤0.035%, N≤0.01%; Preferably, the steel substrate contains the following chemical elements by mass percentage: 0<C≤0.1%, 0<Si≤0.02%, 0<Mn≤0.5%, P≤0.035%, S≤0.035%, N≤0.01%, and the balance is Fe and unavoidable impurities.

8. The steel plate according to any one of claims 2 to 7, characterized in that The yield strength of the steel plate is ≤240MPa; the tensile strength is ≥270MPa, preferably ≥329MPa; the yield strength ratio is ≤0.7; the elongation after fracture A 80 ≥30%; and / or the thickness of the steel plate is 0.4 to 2.0 mm, preferably 0.7 to 1.2 mm.

9. A method for manufacturing the steel plate according to any one of claims 1 to 8, comprising the following steps performed in sequence: 1) cold rolling the hot-rolled steel sheet, and controlling the average surface roughness Sa of the steel sheet after cold rolling to be ≤1.2 μm; 2) Annealing the cold rolled steel sheet; 3) Smoothing the annealed steel plate with a patterned roller to obtain a steel plate with a patterned surface, wherein the surface of the patterned roller has two or more regions with different average surface roughness.

10. The method of claim 9, wherein: The method satisfies at least one of the following conditions: The difference ΔSa between the average surface roughness of two adjacent regions with different average surface roughness in the patterned roller 辊 S ≥1.5μm, preferably ΔSa 辊S 1.5 to 2.8 μm; In step 3), the flattening rate is 1 to 3%, preferably 2 to 3%; In step 3), the pattern on the surface of the patterned roller is obtained by laser texturing. Preferably, When laser texturing the pattern roller, the following relationship is satisfied: Wherein, Ф represents the diameter of the pattern roller, in mm; v represents the rotation speed of the pattern roller, in r / min; f represents the laser switching frequency, in Hz.

11. The steel plate according to claim 1, characterized in that The steel plate comprises a steel substrate and a zinc-aluminum-magnesium coating plated on the surface of the steel substrate, and the surface of the steel plate having a pattern is the outer surface of the zinc-aluminum-magnesium coating.

12. The steel plate according to claim 11, characterized in that The average surface roughness difference ΔSa between two adjacent areas with different average surface roughness on the same side outer surface of the zinc-aluminum-magnesium coating 板L ≥0.4μm, preferably ΔSa 板 L ≥0.8μm.

13. The steel plate according to claim 11, wherein: Any one or more of the two or more regions with different average surface roughness is discontinuous and divided into two or more sub-regions, and the average surface roughness difference ΔSa between the sub-region in one region and the adjacent region or sub-region with different average surface roughness on the same side outer surface of the zinc-aluminum-magnesium coating is 板L ≥0.4μm, preferably ΔSa 板L ≥0.8μm.

14. The steel plate according to any one of claims 11 to 13, wherein: There is a transition zone with a width of ≤0.1 mm between two adjacent regions with different average surface roughness on the same side outer surface of the zinc-aluminum-magnesium coating, and the difference ΔSa′ between the average surface roughness of the transition zone and the average surface roughness of any one of the two adjacent regions with different average surface roughness L Smaller than the average surface roughness difference ΔSa between two adjacent areas with different average surface roughness 板L ; Preferably, the width of the transition zone is 0.04 to 0.07 mm.

15. The steel plate according to any one of claims 11 to 14, wherein The steel substrate contains, in addition to Fe and inevitable impurities, the following chemical elements in terms of mass percentage: 0<C≤0.1%, 0<Si≤0.02%, 0<Mn≤0.5%, P≤0.035%, S≤0.025%, N≤0.01%; Preferably, the steel substrate contains the following chemical elements by mass percentage: 0<C≤0.1%, 0<Si≤0.02%, 0<Mn≤0.5%, P≤0.035%, S≤0.025%, N≤0.01%, and the balance is Fe and unavoidable impurities.

16. The zinc-aluminum-magnesium coated steel sheet according to any one of claims 11 to 15, wherein: The yield strength of the steel plate is ≤240MPa; the tensile strength is ≥270MPa, preferably ≥329MPa; the yield strength ratio is ≤0.7; the elongation after fracture A 80 ≥30%; and / or the thickness of the steel plate is 0.4 to 2.0 mm, preferably 0.8 to 1.6 mm.

17. The steel plate according to any one of claims 11 to 16, wherein: The zinc-aluminum-magnesium coating contains, in addition to Zn and inevitable impurities, the following chemical elements by mass percentage: Al: 1-15%, Mg: 0.1-5%; Preferably, the zinc-aluminum-magnesium coating contains the following chemical elements by mass percentage: Al: 1-15%, Mg: 0.1-5%, and the balance is Zn and unavoidable impurities.

18. A method for manufacturing the steel plate according to any one of claims 11 to 17, comprising the following steps performed in sequence: a) annealing the cold rolled steel sheet; b) hot-dip coating the annealed steel sheet to obtain a steel sheet with a zinc-aluminum-magnesium coating; c) using a patterned roller to flatten the steel plate having a zinc-aluminum-magnesium coating to obtain a steel plate having a pattern on the surface, wherein the surface of the patterned roller has two or more regions with different average surface roughness.

19. The method of claim 18, wherein: The method satisfies at least one of the following conditions: The difference ΔSa between the average surface roughness of two adjacent regions with different average surface roughness in the patterned roller 辊 L ≥1.5μm, preferably ΔSa 辊L 1.5 to 2.8 μm; In step c), the flattening rate is 1 to 3%, preferably 2 to 3%; In step c), the pattern on the surface of the patterned roller is produced by laser texturing; preferably, When laser texturing the pattern roller, the following relationship is satisfied: Wherein, Ф represents the diameter of the pattern roller, in mm; v represents the rotation speed of the pattern roller, in r / min; f represents the laser switching frequency, in Hz.

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