Method for inhibiting dezincification of zinc-aluminum-magnesium strip steel and strip steel

Abstract

This invention relates to the field of strip steel technology, and proposes a method and strip steel for suppressing edge dezincification in zinc-aluminum-magnesium strip steel. The method includes the following steps: S1, hot rolling of a steel billet to obtain hot-rolled strip steel; S2, pickling of the hot-rolled strip steel followed by cold rolling and annealing at 800-840℃ to obtain a semi-finished product; S3, hot-dip galvanizing of the semi-finished product followed by passivation treatment to obtain strip steel. In step S2, the cold rolling compression ratio is 40%-50%. The steel billet is composed of the following weight percentages: C 0.15%-0.20%, Si≤0.07%, Mn 0.70%-0.85%, P≤0.020%, S≤0.020%, Als 0.015%-0.050%, Ti 0.05%-0.07%, with the remainder being Fe and unavoidable impurities. This technical solution solves the problem of edge dezincification in strip steel in related technologies.

Description

Technical Field

[0001] This invention relates to the field of strip steel technology, specifically to a method for inhibiting zinc dezincification at the edges of zinc-aluminum-magnesium strip steel and the strip steel itself. Background Technology

[0002] Zinc-aluminum-magnesium coatings are widely used in photovoltaic brackets, building structures, and automotive parts due to their excellent corrosion resistance and self-healing ability. Continuous hot-dip galvanizing production lines for aluminum-magnesium alloys often employ a modified Sendzimir process. Cold-rolled coils sequentially pass through an annealing furnace heating section, a radiant tube reduction section, a heat preservation section, and a cooling section before entering a zinc pot for hot-dip galvanizing.

[0003] In actual production, dezincification at the edges of strip steel is a common and difficult-to-complete defect, especially when the cold rolling compression ratio is small (≤50%). A small compression ratio means insufficient cold rolling deformation, resulting in coarse grains and low dislocation density in the steel matrix, which poses greater challenges to subsequent annealing reduction and coating bonding.

[0004] Existing technologies primarily address zinc strip dezincification by optimizing the annealing process (e.g., lowering furnace temperature, increasing hydrogen content, and reducing dew point) or adding post-plating treatments. However, these methods have limited effectiveness within the process window of low compression ratio and high-temperature annealing. Therefore, a method to suppress edge zinc strip dezincification in zinc-aluminum-magnesium strip is urgently needed to improve the quality of the finished steel strip. Summary of the Invention

[0005] This invention proposes a method and a strip steel for suppressing zinc dezincification at the edges of zinc-aluminum-magnesium strip steel, in order to solve or alleviate at least one of the above-mentioned problems.

[0006] The technical solution of the present invention is as follows: This invention proposes a method for inhibiting zinc strip dezincification at the edges of zinc-aluminum-magnesium steel strips, comprising the following steps: S1. After hot rolling, steel billets are used to produce hot-rolled strip steel. S2. Hot-rolled strip steel is pickled and then subjected to cold rolling and annealing at 800~840℃ to obtain a semi-finished product; S3. After hot-dip galvanizing with aluminum-magnesium alloy, the semi-finished product is passivated to obtain strip steel. In step S2, the cold rolling compression ratio in the cold rolling process is 40%~50%; The steel billet is composed of the following components by weight percentage: C 0.15%~0.20%, Si≤0.07%, Mn 0.70%~0.85%, P≤0.020%, S≤0.020%, Als 0.015%~0.050%, Ti 0.05%~0.07%, with the remainder being Fe and unavoidable impurities.

[0007] Preferably, in step S1, the initial rolling temperature of the hot rolling is 1080~1200℃, and the final rolling temperature of the hot rolling is 850~900℃.

[0008] Preferably, in step S2, the annealing process at 800~840℃ involves sequentially passing through a heating section, a reduction section, and a cooling section at 800~840℃.

[0009] Preferably, the 800~840℃ heating section uses a dual regenerative burner, the fuel is converter gas, and the TV value of the heating section is 110~120.

[0010] Preferably, the temperature of the reduction section is 680~710℃, the atmosphere is a mixed gas composed of H2 and N2, and the dew point is controlled to be below -45℃.

[0011] Preferably, the cooling section is used to cool the temperature to 440~450°C.

[0012] Preferably, in the mixed gas, H2 accounts for 5% to 10% of the mixed gas volume.

[0013] Preferably, in step S3, the temperature of the zinc-aluminum-magnesium plating solution during hot-dip galvanizing is 440~450℃.

[0014] Preferably, the zinc-aluminum-magnesium plating solution is composed of the following components by weight percentage: Al 5.8%~6.0%, Mg 2.0%~2.5%, with the balance being Zn and unavoidable impurities.

[0015] The present invention also proposes a strip steel prepared by the aforementioned method for inhibiting zinc dezincification at the edges of zinc-aluminum-magnesium strip steel.

[0016] The beneficial effects of this invention are as follows: This invention targets a specific process window of low compression ratio (40%~50%) + high-temperature annealing (800~840℃), controlling the Si content of the steel matrix to ≤0.07%, while reducing the Mn content (0.70%~0.85%) and increasing the Ti content (0.05%~0.07%). This results in strip steel that not only improves the problem of edge dezincification but also possesses high mechanical properties. The reason for this is that under low compression ratio conditions, more of the original hot-rolled microstructure is retained, and the driving force for fragmentation and recrystallization of the hot-rolled microstructure is insufficient. This invention, through a low-silicon design, reduces the precipitation of Si oxides at the strip edge due to high fluctuations in the calorific value of the gas, thereby reducing the risk of rapid temperature increases at the strip edge causing silicon oxides to accumulate and precipitate on the strip surface. Simultaneously, high-temperature annealing promotes recrystallization and grain refinement, ensuring the mechanical properties required for subsequent processing of the strip while avoiding the problem of edge dezincification. Furthermore, the limitation on Mn and Ti content can further improve the mechanical properties of the strip steel. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a scanning electron microscope image (magnification x200) of the steel strip surface in Embodiment 1 of the present invention. Figure 2 The images shown are scanning electron microscope (SEM) images (magnification x200) and energy dispersive spectroscopy (EDS) spectra of the dezincification region at the edge of the strip in Comparative Example 1 of this invention. In the image: the left image is a scanning electron microscope image; the right image is an energy dispersive spectroscopy (EDS) spectrum. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will be described through embodiments.

[0021] A specific embodiment of the first aspect of the present invention provides a method for suppressing zinc strip dezincification at the edges of zinc-aluminum-magnesium steel strip, comprising the following steps: S1. After hot rolling, steel billets are used to produce hot-rolled strip steel. S2. Hot-rolled strip steel is pickled and then subjected to cold rolling and annealing at 800~840℃ to obtain a semi-finished product; S3. After hot-dip galvanizing with aluminum-magnesium alloy, the semi-finished product is passivated to obtain strip steel. In step S2, the cold rolling compression ratio in the cold rolling process is 40%~50%; The steel billet is composed of the following components by weight percentage: C 0.15%~0.20%, Si≤0.07%, Mn 0.70%~0.85%, P≤0.020%, S≤0.020%, Als 0.015%~0.050%, Ti 0.05%~0.07%, with the remainder being Fe and unavoidable impurities; 800~840℃ can be any value from 800℃, 805℃, 810℃, 815℃, 820℃, 825℃, 830℃, 835℃, 840℃, or any range between any two values; and 40%~50% can be any value from 40%, 42%, 44%, 45%, 46%, 48%, 50%, or any range between any two values.

[0022] In one embodiment of the present invention, in step S1, the initial rolling temperature of hot rolling is 1080~1200℃, for example, it can be any point value or any range between any two points among 1080℃, 1100℃, 1110℃, 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, 1180℃, and 1200℃, and the final rolling temperature of hot rolling is 850~900℃, for example, it can be any point value or any range between any two points among 850℃, 860℃, 870℃, 880℃, 890℃, and 900℃.

[0023] In one embodiment of the present invention, in step S2, the annealing process at 800~840℃ involves sequentially passing through a heating section, a reduction section, and a cooling section at 800~840℃. The 800~840℃ can be any point value among 820℃, 825℃, 830℃, 835℃, and 840℃, or a range between any two point values.

[0024] In one embodiment of the present invention, the heating section at 800~840℃ uses a dual regenerative burner, the fuel is converter gas, and the TV value of the heating section is 110~120.

[0025] In one embodiment of the present invention, the temperature of the reduction section is 680~710°C, for example, it can be any point value among 680°C, 690°C, 700°C, and 710°C, or any range between any two point values, the atmosphere is a mixed gas composed of H2 and N2, and the dew point is controlled to be below -45°C.

[0026] In one embodiment of the present invention, the cooling process is to cool to 440~450°C.

[0027] In one embodiment of the present invention, in step S3, when hot-dip galvanizing aluminum-magnesium, the temperature of the zinc-aluminum-magnesium plating solution is 440~450℃, for example, it can be any point value among 440℃, 445℃, and 450℃, or any range between any two point values.

[0028] In one embodiment of the present invention, the zinc-aluminum-magnesium plating bath is composed of the following components by weight percentage: Al 5.8%~6.0%, Mg 2.0%~2.5%, with the balance being Zn and unavoidable impurities.

[0029] A specific embodiment of the second aspect of the present invention provides a strip steel prepared by a method for inhibiting zinc dezincification at the edge of zinc-aluminum-magnesium strip steel provided by a specific embodiment of the first aspect of the present invention.

[0030] The present invention will now be described in detail with reference to preferred embodiments and comparative examples. The preferred embodiments of the present invention described below can be modified in various ways, and therefore the scope of the invention should not be construed as limited to the preferred embodiments described in detail below. Preferred embodiments are provided to help those skilled in the art to more readily understand the present invention.

[0031] In the following embodiments and comparative examples: Product qualification rate: One sample is taken from the edge of each strip steel coil. After cold bending, the sample with no zinc peeling on the edge is considered a qualified sample; Product qualification rate (%) = Number of qualified samples / Total number of tested samples × 100%; The percentage of strip steel samples that did not dezincify after cold bending was determined by taking one sample from each coil of strip steel for testing. Mechanical properties: Yield strength, tensile strength and elongation were determined according to the methods in GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Test at room temperature". TV value is a process indicator that represents heating capacity. TV value = strip thickness (mm) × production line speed (m / min).

[0032] Example 1 A method for inhibiting zinc strip dezincification at the edges of zinc-aluminum-magnesium steel strip includes the following steps: S1. After hot rolling, the steel billet is coiled at 580℃ to obtain a hot-rolled strip with a thickness of 3.5mm. The initial rolling temperature is 1100℃ and the final rolling temperature is 850℃. The steel billet is composed of the following components by weight percentage: C 0.15%, Si 0.06%, Mn 0.80%, P 0.017%, S 0.012%, Al 0.03%, Ti 0.052%, with the remainder being Fe and unavoidable impurities; S2. After pickling, hot-rolled strip steel is cold-rolled with a compression ratio of 43% to obtain a cold-rolled strip steel with a thickness of 2.0mm. Then, it is annealed to obtain a semi-finished product. The annealing process is as follows: cold-rolled strip steel is sequentially processed in a modified Sendzimir process annealing furnace through an 820℃ heating section, a reduction section, and a cooling section (cooled to the temperature of the zinc-aluminum-magnesium plating solution). The heating section uses dual regenerative burners, and the fuel is converter gas with a TV value of 118. The temperature of the reduction section is 680℃, the atmosphere inside the furnace is a mixture of H2 and N2, with H2 accounting for 5% of the volume of the mixture and a dew point of -49℃. S3. The semi-finished product is placed in a 440℃ zinc-aluminum-magnesium plating bath and hot-dip galvanized, aluminum-magnesium coated. The coating thickness is controlled by an air knife (the total weight of the double-sided coating is 275g / m²). Then, the surface flatness of the strip is improved by a finishing machine and a tension leveling machine. Finally, passivation treatment is performed to obtain the finished zinc-aluminum-magnesium strip. The zinc-aluminum-magnesium plating solution is composed of the following components by weight percentage: Al 6.0%, Mg 2.2%, with the balance being Zn and unavoidable impurities; Results of strip steel performance testing: No abnormalities were observed on the edge surface of the strip steel, and SEM electron microscopy revealed no aggregated silicon oxide particles. Of 100 coils of finished galvanized aluminum-magnesium strip steel tested, 96 coils showed no zinc peeling at the edges after cold bending, resulting in a product qualification rate of 96%. Mechanical properties: Rel (yield strength) = 403MPa, Rm (tensile strength) = 536MPa, A (elongation) = 21.0%, meeting S350GD standard.

[0033] Example 2 A method for inhibiting zinc strip dezincification at the edges of zinc-aluminum-magnesium steel strip includes the following steps: S1. After hot rolling, the steel billet is coiled at 650℃ to obtain a hot-rolled strip with a thickness of 3.25mm. The initial rolling temperature is 1100~1180℃ and the final rolling temperature is 900℃. The steel billet is composed of the following components by weight percentage: C 0.15%, Si 0.06%, Mn 0.80%, P 0.017%, S 0.012%, Al 0.03%, Ti 0.052%, with the remainder being Fe and unavoidable impurities; S2. After pickling, hot-rolled strip steel is cold-rolled with a compression ratio of 45% to obtain a cold-rolled strip steel with a thickness of 1.8mm. Then, it is annealed to obtain a semi-finished product. The annealing process is as follows: cold-rolled strip steel is sequentially processed in a modified Sendzimir process annealing furnace through an 840℃ heating section, a reduction section, and a cooling section (cooled to the temperature of the zinc-aluminum-magnesium plating solution). The heating section uses dual regenerative burners, and the fuel is converter gas with a TV value of 118. The temperature of the reduction section is 710℃, and the atmosphere inside the furnace is a mixture of H2 and N2, with H2 accounting for 10% of the volume of the mixture and a dew point of -49℃. S3. The semi-finished product is placed in a 450℃ zinc-aluminum-magnesium plating bath and hot-dip galvanized, aluminum-magnesium coated. The coating thickness is controlled by an air knife (the total weight of the double-sided coating is 275g / m²). Then, the surface flatness of the strip is improved by a finishing machine and a tension leveling machine. Finally, passivation treatment is performed to obtain the finished zinc-aluminum-magnesium strip. The zinc-aluminum-magnesium plating solution is composed of the following components by weight percentage: Al 6.0%, Mg 2.5%, with the balance being Zn and unavoidable impurities; Results of strip steel performance testing: No abnormalities were observed on the edge surface of the strip steel, and SEM electron microscopy revealed no aggregated silicon oxide particles. Of 100 coils of finished galvanized aluminum-magnesium strip steel tested, 97 coils showed no zinc peeling at the edges after cold bending, resulting in a product qualification rate of 97%. Mechanical properties: Rel=398MPa, Rm=530MPa, A=22.0%, meeting S350GD standard.

[0034] Example 3 Except for the different composition of the steel billet, the annealing temperature of the heating section is 810℃, and the cold rolling compression ratio is 50%, the rest of this embodiment is the same as that of Example 1. In this embodiment, the steel billet is composed of the following components by weight percentage: C 0.15%, Si 0.07%, Mn 0.70%, P 0.014%, S 0.015%, Als 0.015%, Ti 0.05%, with the remainder being Fe and unavoidable impurities.

[0035] Results of strip steel performance testing: The surface of the strip steel edges showed no abnormalities, and SEM electron microscopy revealed no aggregated silicon oxide particles. Of 100 coils of finished galvanized aluminum-magnesium strip steel tested, 95 coils showed no zinc peeling at the edges after cold bending, resulting in a product qualification rate of 95%. Mechanical properties: Rel=370MPa, Rm=470MPa, A=20%, meeting S350GD standard.

[0036] Example 4 Except for the different composition of the steel billet, the annealing temperature of the heating section is 840℃, and the cold rolling compression ratio is 40%, the rest of this embodiment is the same as that of Example 1. In this embodiment, the steel billet is composed of the following components by weight percentage: C 0.20%, Si 0.05%, Mn 0.85%, P 0.020%, S 0.020%, Als 0.05%, Ti 0.07%, with the remainder being Fe and unavoidable impurities.

[0037] Results of strip steel performance testing: No abnormalities were observed on the edge surface of the strip steel, and SEM electron microscopy revealed no aggregated silicon oxide particles. Of 100 coils of finished galvanized aluminum-magnesium strip steel tested, 96 coils showed no zinc peeling at the edges after cold bending, resulting in a product qualification rate of 96%. Mechanical properties: Rel=390MPa, Rm=520MPa, A=18%, meeting S350GD standard.

[0038] Comparative Example 1 This comparative example is the same as Example 1 except for the steel billet composition; The steel billet in this comparative example consists of the following components: C 0.17%, Si 0.22%, Mn 1.10%, P 0.018%, S 0.011%, Als 0.025%, Ti 0.025%, with the remainder being Fe and unavoidable impurities.

[0039] Strip steel performance test results: A large number of silicon oxide particles (such as...) are present at the edge of the strip steel. Figure 2 As shown in the figure); 100 coils of finished galvanized aluminum-magnesium steel strip were tested, and after cold bending, 42 coils showed intermittent dezincification within a range of 0~20mm (from the edge inward), with a product qualification rate of 58%; Mechanical properties: Rel=375MPa, Rm=485MPa, A=19%, meeting S350GD standard.

[0040] Comparative Example 2 This comparative example is the same as Example 1 except that the annealing temperature of the heating section is 770°C. Results of strip steel performance testing: The strip steel edge surface showed no abnormalities. Of the 100 coils of finished galvanized aluminum-magnesium strip steel tested, 90 coils showed no zinc peeling at the edges after cold bending, resulting in a product qualification rate of 90%. Mechanical properties: Rel=400MPa, Rm=520MPa, A=14.5%, elongation does not meet S350GD standard.

[0041] Note: Under low compression ratios, simply reducing Si without using a sufficiently high annealing temperature cannot achieve the required mechanical properties. This invention solves both the dezincification and mechanical property issues through the synergistic control of low silicon content and high-temperature annealing.

[0042] Comparative Example 3 This comparative example is the same as Example 1 except that the Mn content in the steel billet is 0.55% (by weight). Results of strip steel performance testing: The surface of the strip steel edges was normal. Of the 100 coils of finished galvanized aluminum-magnesium strip steel tested, 88 coils showed no zinc peeling at the edges after cold bending, resulting in a product qualification rate of 88%. Mechanical properties: Rel=332MPa, Rm=415MPa, A=22%, yield strength and tensile strength do not meet the S350GD standard.

[0043] Comparative Example 4 This comparative example is the same as Example 1 except that the Mn content in the steel billet is 1.5% (by weight percentage); Results of strip steel performance testing: No abnormalities were found on the surface of the strip edge. Of the 100 coils of finished galvanized aluminum-magnesium strip tested, 81 coils showed no zinc peeling on the edge after cold bending, but a large number of MnS inclusions were found inside the strip. The product qualification rate was 81%. Mechanical properties: Rel=445MPa, Rm=582MPa, A=14.5%, which does not meet the S350GD standard.

[0044] Comparative Example 5 This comparative example is the same as Example 1 except that the Ti content in the steel billet is 0.03% (by weight). Results of strip steel performance testing: The surface of the strip steel edges was normal. Of the 100 coils of finished galvanized aluminum-magnesium strip steel tested, 83 coils showed no zinc peeling at the edges after cold bending, with a product qualification rate of 83%. Mechanical properties: Rel=346MPa, Rm=425MPa, A=19.3%, yield strength is low and does not meet S350GD standard.

[0045] Comparative Example 6 This comparative example is the same as Example 1 except that the Ti content in the billet is 0.08% (by weight). Results of strip steel performance testing: The surface of the strip steel edges was normal. Of the 100 coils of finished galvanized aluminum-magnesium strip steel tested, 78 coils showed no zinc peeling at the edges after cold bending, resulting in a product qualification rate of 78%. Mechanical properties: Rel=438MPa, Rm=575MPa, A=14.8%, the steel matrix has too many precipitates and the elongation does not meet the S350GD standard.

[0046] Comparative Example 7 This comparative example is the same as Example 1 except that the cold-rolled compression ratio is 30%. Results of strip steel performance testing: Insufficient cold rolling deformation and incomplete recrystallization led to cracking during strip processing. While the strip edge surface showed no abnormalities, out of 100 coils of finished galvanized aluminum-magnesium strip tested, 65 coils showed no zinc peeling at the edges after cold bending, resulting in a product qualification rate of 65%. Mechanical properties: Rel=480MPa, Rm=560MPa, A=11%, does not meet the S350GD standard.

[0047] Comparative Example 8 This comparative example is the same as Example 1 except that the cold-rolled compression ratio is 60%. Results of strip steel performance testing: No abnormalities were found on the edge surface of the strip steel. Of the 100 coils of finished galvanized aluminum-magnesium strip steel tested, 92 coils showed no zinc peeling on the edge after cold bending. However, the cold rolling load was too high, the risk of strip breakage increased, production efficiency decreased, and costs increased significantly. The product qualification rate was 92%. Mechanical properties: Rel=380MPa, Rm=500MPa, A=24%, meeting the S350GD standard; however, it exceeds the applicable scenario of "small compression ratio" of this invention.

[0048] Comparative Example 9 This comparative example is the same as Example 1 except that the annealing temperature of the heating section is 780°C. Results of strip steel performance testing: The surface of the strip steel edge was normal. Of the 100 coils of finished galvanized aluminum-magnesium strip steel tested, 61 coils showed no zinc de-zincification at the edge after cold bending, but recrystallization was incomplete, resulting in a product qualification rate of 61%. Mechanical properties: Rel=392MPa, Rm=520MPa, A=13.8%, which does not meet the requirements of S350GD; Comparative Example 10 This comparative example is the same as Example 1 except that the annealing temperature of the heating section is 870°C. Results of strip steel performance testing: Excessive temperature causes overheating of the strip edges, resulting in coarse grains and reduced coating adhesion. The surface of the strip steel edges was normal. Of the 100 coils of finished galvanized aluminum-magnesium strip steel tested, 70 coils showed no zinc peeling at the edges after cold bending, resulting in a product qualification rate of 70%. The mechanical properties fluctuate greatly, and the surface roughness exceeds the standard, but the mechanical properties are qualified; mechanical properties: Rel=360MPa, Rm=470MPa, A=21%, which meets the requirements of S350GD.

[0049] By comparing the above Examples 1-4 and Comparative Examples 1-10, it can be seen that when the cold rolling compression ratio is ≤50%, by limiting the annealing temperature and composition, the problem of insufficient microstructure and properties caused by the small compression ratio can be made up, the dezincification problem at the edge of the strip can be suppressed, the mechanical properties of the strip can be improved, and the process stability is high.

[0050] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of suppressing dezincification of the edge portion of a zinc-aluminum-magnesium strip steel, characterized by, Includes the following steps: S1. After hot rolling, steel billets are used to produce hot-rolled strip steel. S2. Hot-rolled strip steel is pickled and then subjected to cold rolling and annealing at 800~840℃ to obtain a semi-finished product; S3. After hot-dip galvanizing with aluminum-magnesium alloy, the semi-finished product is passivated to obtain strip steel. In step S2, the cold rolling compression ratio in the cold rolling process is 40%~50%; The steel billet is composed of the following components by weight percentage: C 0.15%~0.20%, Si≤0.07%, Mn 0.70%~0.85%, P≤0.020%, S≤0.020%, Als 0.015%~0.050%, Ti 0.05%~0.07%, with the remainder being Fe and unavoidable impurities.

2. The method of claim 1, wherein the zinc-aluminum-magnesium steel strip is a cold-rolled steel strip. In step S1, the initial rolling temperature of the hot rolling is 1080~1200℃, and the final rolling temperature of the hot rolling is 850~900℃.

3. The method of claim 1, wherein the zinc-aluminum-magnesium coated steel strip is characterized by, In step S2, the annealing process at 800~840℃ involves sequentially passing through a heating section, a reduction section, and a cooling section at 800~840℃.

4. The method of claim 3, wherein the zinc-aluminum-magnesium coated steel strip is a hot-dipped galvalume coated steel strip. The 800~840℃ heating section uses a dual regenerative burner and is fueled by converter gas. The TV value of the heating section is 110~120.

5. The method of claim 3, wherein the zinc-aluminum-magnesium coated steel strip is a hot-dipped galvalume coated steel strip. The temperature of the reduction section is 680~710℃, and the atmosphere is a mixed gas composed of H2 and N2, with the dew point controlled below -45℃.

6. The method for inhibiting zinc strip dezincification at the edges of zinc-aluminum-magnesium strip according to claim 3, characterized in that, The cooling section is used to cool the temperature to 440~450℃.

7. The method for inhibiting zinc strip dezincification at the edges of zinc-aluminum-magnesium strip according to claim 5, characterized in that, In the mixed gas, H2 accounts for 5% to 10% of the mixed gas volume.

8. The method for inhibiting zinc strip dezincification at the edges of zinc-aluminum-magnesium strip according to claim 1, characterized in that, In step S3, during the hot-dip zinc-aluminum-magnesium plating process, the temperature of the zinc-aluminum-magnesium plating solution is 440~450℃.

9. A method for inhibiting zinc strip dezincification at the edges of zinc-aluminum-magnesium steel strip according to claim 8, characterized in that, The zinc-aluminum-magnesium plating solution consists of the following components by weight percentage: Composition: Al 5.8%~6.0%, Mg 2.0%~2.5%, balance Zn and unavoidable impurities.

10. A strip steel, characterized in that, It is prepared by any one of the methods for inhibiting zinc dezincification at the edge of zinc-aluminum-magnesium strip steel according to claims 1 to 9.

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