Alloyed hot-dip galvanized steel sheet having excellent surface adhesive performance and manufacturing method therefor

Abstract

Disclosed in the present invention is an alloyed hot-dip galvanized steel sheet having excellent surface adhesive performance, comprising a substrate, wherein a surface of the substrate has an alloyed hot-dip galvanized layer; the surface of the alloyed hot-dip galvanized layer is covered with a composite nanostructure treatment layer; the composite nanostructure treatment layer comprises nanoparticles and irregular nanostructures; the nanoparticles are randomly distributed on the surface of the alloyed hot-dip galvanized layer at least in an acicular form; and the irregular nanostructures have active groups for optimizing the chemical bonding performance of the surface of the alloyed hot-dip galvanized layer. Further disclosed in the present invention is a manufacturing method for an alloyed hot-dip galvanized steel sheet, comprising the steps of: performing hot-dip galvanization, alloying heat treatment, and skin passing on a substrate to form an alloyed hot-dip galvanized layer on a surface of the substrate; and performing surface treatment on the alloyed hot-dip galvanized layer by using a water-based treatment agent to obtain a composite nanostructure treatment layer.

Description

Alloyed hot-dip galvanized steel sheet having excellent surface bonding properties and method for manufacturing the same TECHNICAL FIELD

[0001] The present invention relates to a steel sheet and a method for manufacturing the same, and more particularly, to a zinc-plated steel sheet and a method for manufacturing the same. BACKGROUND

[0002] The bonding properties of a vehicle body material directly affect the structural stability and collision safety thereof, and thus the bonding properties of a vehicle body steel sheet need to be ensured. Factors affecting the surface bonding properties of a vehicle body material include physical properties and chemical properties. The physical properties are mainly affected by the adhesion of an adhesive to a surface physical profile and the bonding force of a surface layer, and the chemical properties are mainly affected by the surface tension and the chemical activity of an extreme surface layer.

[0003] At the end of the last century, the automobile industry promoted the widespread use of a single-function phosphate lubricant film technology to solve the problem of insufficient surface formability of an automobile galvanized steel sheet. However, the phosphate compound of the plated layer directly changes the chemical composition of the surface, and in the bonding process, the phosphate and the adhesive interact to form a barrier layer, which hinders the effective bonding of the adhesive to the metal surface. In addition, the bonding properties of the phosphate and the adhesive are poor, and the bonding properties are easily insufficient.

[0004] In recent years, as the automobile industry has further increased its attention to the bonding properties, the bonding strength requirements have gradually increased. The problem of a decrease in the surface bonding properties of a single-function phosphate lubricant film product has been revealed in application practice. In the prior art, for example:

[0005] Chinese Patent Literature No. CN101910466A, published on December 8, 2010, entitled "Zinc alloy coated steel sheet having good sealant adhesion and corrosion resistance and method for manufacturing the same" discloses a zinc alloy plated steel sheet having good sealant adhesion and corrosion resistance. The method for improving the corrosion resistance and sealant adhesion properties of an automobile alloy plated steel sheet is mainly a method of depositing a metal layer having a thickness of 0.1-1 micrometers on the surface of an alloy plated galvanized steel sheet by vacuum deposition.

[0006] For another example, Chinese Patent Literature No. CN102666903A, published on September 12, 2012, entitled "Alloyed hot-dip galvanized steel sheet having excellent formability and peeling resistance after bonding and method for manufacturing the same" discloses an alloyed hot-dip galvanized steel sheet having excellent formability and peeling resistance after bonding and a method for manufacturing the same. The method mainly forms a mixed layer containing a composite oxide of Mn, Zn, and P and a water-soluble P compound on the surface of the plated layer, and mainly controls the composition ratio to achieve the optimization of the lubrication and bonding properties of the alloy plated steel sheet. However, this technology contains a P compound, and the environmental performance is insufficient. SUMMARY

[0007] One of the objectives of the present application is to provide an alloyed hot-dip galvanized steel sheet with excellent surface bonding performance, which has good bonding performance and can improve the overall strength of the bonded structure during service and optimize the stability of the bonding performance.

[0008] To achieve the above-mentioned objectives, the present application provides an alloyed hot-dip galvanized steel sheet with excellent surface bonding performance, comprising a substrate, wherein the surface of the substrate has an alloyed hot-dip galvanized layer;

[0009] The surface of the alloyed hot-dip galvanized layer is covered with a composite nanostructure treatment layer; the composite nanostructure treatment layer comprises nanoparticles and irregular nanostructures;

[0010] The nanoparticles are randomly distributed on the surface of the alloyed hot-dip galvanized layer in at least a needle-like form;

[0011] The irregular nanostructures have active groups that optimize the chemical bonding performance of the surface of the alloyed hot-dip galvanized layer.

[0012] In the present application, the nanoparticles are randomly distributed on the surface of the alloyed hot-dip galvanized layer mainly in a needle-like and short rod-like form, wherein the needle-like nanoparticles enhance the adhesion by increasing the contact area and physical riveting effect between the adhesive and the alloyed hot-dip galvanized layer, promote the uniform distribution of stress after the adhesive is cured, and thus improve the bonding performance.

[0013] In the present application, the active groups can increase the effective contact area of the bonding and form good adhesion and a more secure joint, thereby improving the chemical resistance of the bonding.

[0014] Further, the substrate can be selected from conventional steel sheets in the art, preferably conventional zinc-platable steel sheets in the art. The shape and thickness of the substrate are not particularly limited herein and can be appropriately selected according to the application field of the substrate. In some embodiments, the substrate comprises, in mass percentage: 0.01-0.20 wt% of C, 0.10-0.50% of Si, 0.10-0.50% of Mn, P≤0.020%, S≤0.0150%, and 0.01-0.05% of Ti, with the balance being Fe and unavoidable impurities. In some embodiments, the substrate is a DC53 steel sheet. In some embodiments, an exemplary alloyed hot-dip galvanized steel sheet is a DC53D+ZF cold-rolled hot-dip galvanized ferrous alloy steel sheet with a tensile strength of 340-420 MPa, a yield strength of 180-260 MPa, an elongation after fracture of≥30%, and a hardness (HB) of 100-150, wherein the surface of the alloyed hot-dip galvanized steel sheet is covered with the composite nanostructure treatment layer described herein.

[0015] Further, in the alloyed hot-dip galvanized steel sheet according to the present application, the thickness of the alloyed hot-dip galvanized layer is not particularly limited. The alloyed hot-dip galvanized layer can have a thickness (e.g., 30 to 150 g / m 2 ) that is conventional in the art, as long as the use and bonding properties of the galvanized steel sheet are not adversely affected.

[0016] Further, in the alloyed hot-dip galvanized steel sheet according to the present application, the alloyed hot-dip galvanized layer contains Fe and Al, and at least one of Bi, Cd, Co, Ni, and Sn.

[0017] In the present application, when the mass percentage of Fe in the Zn-Fe alloy phase in the alloyed hot-dip galvanized layer is too low, the alloyed steel sheet surface is prone to have a defect of poor alloying, which significantly increases the roughness of the plated layer surface and increases the friction coefficient of the plated layer surface. When the mass percentage of Fe in the Zn-Fe alloy phase in the alloyed hot-dip galvanized layer is too high, a phase with high hardness and large brittleness is easily formed in the plated layer, and this brittle structure causes the phenomenon that the bonding force of the plated layer is lower than the bonding force of the adhesive interface during the adhesive peeling process, thereby causing the problem of peeling of the plated layer. In some embodiments, the mass percentage of Fe in the Zn-Fe alloy phase in the alloyed hot-dip galvanized layer is preferably controlled to be 9% to 10%.

[0018] Further, in the alloyed hot-dip galvanized steel sheet according to the present application, the alloyed hot-dip galvanized layer contains Al and at least one of Bi, Cd, Co, Ni, and Sn.

[0019] Further, in the alloyed hot-dip galvanized steel sheet according to the present application, the mass percentage of Al in the alloyed hot-dip galvanized layer is 0.03% to 0.2%.

[0020] In the present application, the main role of Al in the alloyed hot-dip galvanized layer is to improve the uniformity of the plated layer, thereby ensuring the appearance quality of the product. When the mass percentage of Al in the alloyed hot-dip galvanized layer is too low, the alloyed hot-dip galvanized layer is prone to have a non-uniform phenomenon, which directly affects the uniformity of the surface bonding strength during the gluing process. When the mass percentage of Al in the alloyed hot-dip galvanized layer is too high, the surface brittleness of the alloyed hot-dip galvanized layer increases, and the zinc powder peeling phenomenon is easily generated during the adhesive peeling process. In some embodiments, the mass percentage of Al in the alloyed hot-dip galvanized layer is further controlled to be 0.08% to 0.15%.

[0021] Further, in the alloyed hot-dip galvanized steel sheet according to the present application, the total mass percentage of Bi, Cd, Co, Ni, and Sn in the alloyed hot-dip galvanized layer is not more than 0.1%.

[0022] In the present application, the Bi, Cd, Co, Ni, Sn elements in the alloyed hot-dip galvanized layer can be combined with the manufacturing process requirements to further optimize the hardness and uniformity of the plating layer.

[0023] Further, in the alloyed hot-dip galvanized steel plate described in the present application, the surface of the alloyed hot-dip galvanized layer has a zinc-iron alloy crystalline region and randomly distributed platform regions, and the area ratio of the zinc-iron alloy crystalline region in a unit area of the surface is 15%-85%. In some embodiments, in the alloyed hot-dip galvanized steel plate described in the present application, the surface of the alloyed hot-dip galvanized layer is only composed of zinc-iron alloy crystalline regions and platform regions. The area ratio of the zinc-iron alloy crystalline region in a unit area can be obtained by identifying the platform regions and calculating the area ratio.

[0024] In the present application, the platform region is formed by using a smoothing roller to process the surface of the alloyed hot-dip galvanized steel plate in the smoothing step in the manufacturing method of the alloyed hot-dip galvanized steel plate. In some embodiments, the smoothing rate in the smoothing step is 0.4-1.8%.

[0025] In the present application, when the area ratio of the zinc-iron alloy crystalline region is less than 15%, the surface roughness of the zinc-iron alloy plating layer decreases, and the surface bonding performance decreases; when the area ratio of the zinc-iron alloy crystalline region is greater than 85%, the surface roughness of the zinc-iron alloy plating layer is high and difficult to control stably, affecting the subsequent coating appearance quality.

[0026] Further, in the alloyed hot-dip galvanized steel plate described in the present application, the equivalent spherical radius of the nanoparticles is 30-200 nm.

[0027] In the present application, when the equivalent spherical radius of the nanoparticles is less than 30 nm, the microstructure formed on the metal surface is not sufficient to provide effective mechanical anchoring, thereby reducing the adhesive performance. When the equivalent spherical radius of the nanoparticles is higher than 200 nm, it is easy to cause local stress concentration on the metal surface, thereby reducing the stable effect of the adhesive performance of the metal surface. In some embodiments, the equivalent spherical radius of the nanoparticles can be further controlled to be 50-150 nm.

[0028] Further, in the alloyed hot-dip galvanized steel plate described in the present application, the needle-shaped nanoparticles contain a metal-based compound, and the metal in the metal-based compound is selected from at least one of Na, Al, Ca, Zn, Ag, Mg and Zr.

[0029] Further, the metal-based compound is at least one of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate, sodium aluminate, calcium nitrate, calcium acetate, calcium sulfate, zirconium acetate, zinc acetate, zinc sulfate, zinc nitrate, magnesium sulfate, magnesium citrate, magnesium lactate, zirconium borate, silver nitrate, silver sulfate, ammonium fluorozirconate, potassium fluorozirconate, and ammonium zirconium carbonate. Preferably, the metal-based compound is selected from one or more of aluminum nitrate, zirconium borate, magnesium sulfate, calcium nitrate, sodium aluminate, magnesium citrate, zinc acetate, silver nitrate, potassium fluorozirconate, aluminum sulfate, and silver sulfate.

[0030] The nanoparticles in this invention also contain non-metallic elements, which may include two or more elements selected from Si, O, C, N and H. Their main function is to combine with metallic elements through coordinate bonds to form the nanoparticle structure.

[0031] Furthermore, in the alloyed hot-dip galvanized steel sheet of the present invention, the proportion of needle-like nanoparticles to all nanoparticles per unit area of ​​the surface is 20%-70%.

[0032] In this invention, by rationally controlling the proportion of needle-shaped nanoparticles to all nanoparticles, their physical bonding function can be more fully utilized. When the proportion of needle-shaped nanoparticles to all nanoparticles is less than 20%, the contact area between the adhesive and the metal surface is not sufficiently increased, resulting in an insignificant adhesive optimization effect. When the proportion of needle-shaped nanoparticles to all nanoparticles is greater than 70%, the needle-shaped crystalline particles are prone to local aggregation and have excessively small gaps, thereby limiting the penetration of the adhesive on the material surface and making it difficult to fully wet the crystals, leading to a decrease in adhesive performance. In some embodiments, the proportion of needle-shaped nanoparticles to all nanoparticles per unit area of ​​the surface is 30%-60%.

[0033] Furthermore, in the alloyed hot-dip galvanized steel sheet of the present invention, the active groups account for 6%-70% of the mass of the irregular nanostructure.

[0034] In this invention, when the mass percentage of active groups in the irregular nanostructure is greater than 70%, the excessive number of active groups leads to over-polymerization of the adhesive during coating, resulting in an uneven bonding surface, reduced adhesive coverage, and consequently poor bonding performance. When the mass percentage of active groups in the irregular nanostructure is less than 6%, the insufficient number of active groups cannot achieve a significant effect in optimizing bonding performance. In some embodiments, the mass percentage of active groups in the irregular nanostructure can be further controlled to 20-50%.

[0035] Furthermore, in the alloyed hot-dip galvanized steel sheet of the present invention, the active groups include amino groups and carboxyl groups.

[0036] In this invention, the main function of the amino group is to increase the wettability of the surface with the adhesive, making the adhesive easier to penetrate and diffuse, increasing the effective contact area of ​​the adhesive and forming good adhesion; the main function of the carboxyl group is to enhance the chemical bond, directly forming chemical bonds with functional groups such as hydroxyl and amino groups in the adhesive to form a stronger bond, thereby improving the chemical resistance of the adhesive and making its performance more stable in harsh environments.

[0037] Furthermore, in the alloyed hot-dip galvanized steel sheet of the present invention, the molar percentage of amino groups and carboxyl groups is 10%-150%.

[0038] In this invention, when the molar percentage of amino groups to carboxyl groups is less than 10%, the low proportion of amino groups prevents the adhesive from effectively optimizing surface penetration and diffusion, resulting in insignificant optimization of adhesive performance. When the molar percentage of amino groups to carboxyl groups is greater than 150%, the proportion of carboxyl groups is too low, chemical bonding is insufficient, and the adhesive structure lacks performance stability in typical chemically resistant environments. In some embodiments, the molar percentage of amino groups to carboxyl groups is preferably controlled between 17% and 120%. In some embodiments, the molar percentage of amino groups to carboxyl groups is preferably controlled between 40% and 150%. In some embodiments, the molar percentage of amino groups to carboxyl groups is preferably controlled between 40% and 120%.

[0039] In some embodiments, the active group is provided by at least one selected from 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, tannic acid, cysteine, mercaptoacetic acid, mercaptoethanol, mercaptoethanol, polyethyleneimine, glycine, aspartic acid, ammonia, ethanolamine, propanolamine, isopropanolamine, ethylsilanol, and propylenesilanol. In some embodiments, the active group is provided by one or more selected from 3,4,5-trihydroxybenzoic acid, ammonia, tartaric acid, isopropanolamine, ethylsilanol, aspartic acid, oxalic acid, ethylsilanol, ethanolamine, polyethyleneimine, citric acid, and ethylenediaminetetraacetic acid.

[0040] Furthermore, in the alloyed hot-dip galvanized steel sheet of the present invention, the nanoparticles account for 20%-60% of the mass percentage in the composite nanostructure treatment layer.

[0041] In this invention, when the mass percentage of nanoparticles in the composite nanostructure treatment layer is less than 20%, the microstructure is insufficient to provide adequate and effective mechanical anchoring, thereby reducing the adhesive performance optimization effect. When the mass percentage of nanoparticles in the composite nanostructure treatment layer is greater than 60%, the proportion of active groups that enhance chemical bonds decreases, and an excessively high proportion of nanoparticle structure leads to instability in adhesive performance optimization, especially under service aging conditions, which may result in a decline in adhesive layer performance. In some embodiments, the mass percentage of nanoparticles in the composite nanostructure treatment layer can be further controlled to 30%-50%.

[0042] Furthermore, in the alloyed hot-dip galvanized steel sheet of the present invention, the composite nanostructure treatment layer is composed of nanoparticles and irregular nanostructures. Furthermore, in the alloyed hot-dip galvanized steel sheet of the present invention, the irregular nanostructures account for 40%-80% by mass in the composite nanostructure treatment layer, such as 50%-70% or 40%-60%.

[0043] In some embodiments, the composite nanostructure treatment layer contains at least one of: aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate, sodium aluminate, calcium nitrate, calcium acetate, calcium sulfate, zirconium acetate, zinc acetate, zinc sulfate, zinc nitrate, magnesium sulfate, magnesium citrate, magnesium lactate, zirconium borate, silver nitrate, silver sulfate, ammonium fluorozirconate, potassium fluorozirconate, and ammonium zirconium carbonate, preferably containing one or more of aluminum nitrate, zirconium borate, magnesium sulfate, calcium nitrate, sodium aluminate, magnesium citrate, zinc acetate, silver nitrate, potassium fluorozirconate, aluminum sulfate, and silver sulfate; and ( 2) At least one of 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, tannic acid, cysteine, mercaptoacetic acid, mercaptoethanol, mercaptoethanol, polyethyleneimine, glycine, aspartic acid, ammonia, ethanolamine, propanolamine, isopropanolamine, ethylsilanol, and propenylsilanol, preferably containing one or more of 3,4,5-trihydroxybenzoic acid, ammonia, tartaric acid, isopropanolamine, ethylsilanol, aspartic acid, oxalic acid, ethylsilanol, ethanolamine, polyethyleneimine, citric acid, and ethylenediaminetetraacetic acid.

[0044] Furthermore, in the alloyed hot-dip galvanized steel sheet of the present invention, the composite nanostructure treatment layer is prepared by a water-based treatment agent comprising the first and second substances described in any embodiment herein, through a coating and drying method. In some embodiments, coating is selected from roll coating, spraying, and dipping. In some embodiments, drying is selected from purging and baking.

[0045] In this invention, the thickness of the composite nanostructure treatment layer in the alloyed hot-dip galvanized steel sheet can be 10-100 g / m. 2 .

[0046] Another objective of this invention is to provide a method for manufacturing alloyed hot-dip galvanized steel sheet. This method involves hot-dip galvanizing, alloying heat treatment, and flattening of a substrate, followed by surface treatment, thereby conveniently and economically obtaining an alloyed hot-dip galvanized steel sheet with excellent surface bonding performance.

[0047] To achieve the above objectives, the present invention provides a method for manufacturing alloyed hot-dip galvanized steel sheet, comprising the following steps:

[0048] The substrate is subjected to hot-dip galvanizing, alloying heat treatment and flattening to form the alloyed hot-dip zinc plating layer on the substrate surface;

[0049] The alloyed hot-dip galvanized layer is surface-treated with a water-based treatment agent to obtain the composite nanostructure treatment layer.

[0050] Furthermore, in the manufacturing method described in this invention, the water-based treatment agent contains a first substance providing a metal-based compound and a second substance providing active groups, wherein the mass ratio of the first substance and the second substance is 1:1 to 1:15. In some embodiments, the concentration of the first substance in the water-based treatment agent is 0.5wt% to 6wt%, and the concentration of the second substance is 1wt% to 8wt%, preferably 0.5wt% to 1.5wt% or 1.5wt% to 6wt%, and preferably 1wt% to 3.2wt% or 3.2wt% to 8wt%.

[0051] Further, in the manufacturing method described in this invention, the first substance is selected from at least one of: aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate, sodium aluminate, calcium nitrate, calcium acetate, calcium sulfate, zirconium acetate, zinc acetate, zinc sulfate, zinc nitrate, magnesium sulfate, magnesium citrate, magnesium lactate, zirconium borate, silver nitrate, silver sulfate, ammonium fluorozirconate, potassium fluorozirconate, and ammonium zirconium carbonate. Preferably, the first substance is selected from one or more of aluminum nitrate, zirconium borate, magnesium sulfate, calcium nitrate, sodium aluminate, magnesium citrate, zinc acetate, silver nitrate, potassium fluorozirconate, aluminum sulfate, and silver sulfate.

[0052] Further, in the manufacturing method of the present invention, the second substance is selected from at least one of the following: 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, tannic acid, cysteine, mercaptoacetic acid, mercaptoethanol, mercaptoethanol, polyethyleneimine, glycine, aspartic acid, ammonia, ethanolamine, propanolamine, isopropanolamine, ethylsilanol, and propylenesilanol. Preferably, the second substance is selected from one or more of the following: 3,4,5-trihydroxybenzoic acid, ammonia, tartaric acid, isopropanolamine, ethylsilanol, aspartic acid, oxalic acid, ethylsilanol, ethanolamine, polyethyleneimine, citric acid, and ethylenediaminetetraacetic acid.

[0053] When a water-based treatment agent contains two or more primary substances, there is no particular limitation on the proportion of each primary substance, as long as the total mass concentration of all primary substances in the water-based treatment agent is between 0.5 wt% and 6 wt%. Similarly, when a water-based treatment agent contains two or more secondary substances, there is also no particular limitation on the proportion of each secondary substance, as long as the total mass concentration of all secondary substances in the water-based treatment agent is between 1 wt% and 8 wt%.

[0054] Furthermore, in the manufacturing method described in this invention, conventional processes in the art can be used to galvanize the substrate, such as hot-dip galvanizing the substrate by immersing it in a zinc plating bath. In some embodiments, the zinc plating bath includes Zn and Al; preferably, the Al content is 0.03–0.20 wt%. In some embodiments, the zinc plating bath may also contain trace amounts of one or more of Bi, Cd, Co, Ni, and Sn elements, the total amount of which preferably does not exceed 0.1 wt%.

[0055] Furthermore, in the manufacturing method described in this invention, the temperature of the alloying heat treatment is 470-500°C.

[0056] Furthermore, in the manufacturing method described in this invention, the holding time for the alloying heat treatment is 2-6 seconds.

[0057] Furthermore, in the manufacturing method described in this invention, the flatness rate of the flattening is 0.4%-1.8%, preferably 0.4%-1%.

[0058] Furthermore, in the manufacturing method described in this invention, the water-based treatment agent is coated onto the alloyed hot-dip galvanized layer by roller coating, spraying or immersion coating for surface treatment, and then dried into a film by blowing or drying.

[0059] The alloyed hot-dip galvanized steel sheet with excellent surface bonding performance and its manufacturing method described in this invention have the following characteristics and beneficial effects:

[0060] The alloyed hot-dip galvanized steel sheet with excellent surface bonding performance described in this invention has good bonding properties, which can improve the overall strength of the bonded structure during service and optimize the stability of the adhesive performance.

[0061] The surface treatment layer of the alloyed hot-dip galvanized steel sheet with excellent surface bonding performance described in this invention is environmentally friendly and phosphorus-free, avoiding the negative environmental impact of phosphorus-containing surface chemical treatments and thus exhibiting higher environmental friendliness.

[0062] The manufacturing method of the alloyed hot-dip galvanized steel sheet with excellent surface bonding performance described in this invention is convenient and economical, with low manufacturing costs, and the product has broad market application prospects. Attached Figure Description

[0063] Figure 1 shows a schematic diagram comparing the adhesive properties of alloyed hot-dip galvanized steel sheets of Example 1 and Comparative Example 1 of the present invention.

[0064] Figure 2 shows that the surface of the alloyed hot-dip galvanized layer of the present invention has zinc-iron alloy crystalline regions and randomly distributed plateau regions; the plateau regions can be identified and their area proportions calculated using the ImageJ image processing software. In the figure, the black parts represent the plateau regions. Detailed Implementation

[0065] The following will further explain and illustrate the alloyed hot-dip galvanized steel sheet with excellent surface bonding performance and its manufacturing method according to specific embodiments of the present invention. However, this explanation and illustration do not constitute an undue limitation on the technical solution of the present invention.

[0066] Examples 1-7 and Comparative Example 1

[0067] The alloyed hot-dip galvanized steel sheets of Examples 1-7 of this invention were all prepared by the following method:

[0068] (1) Obtaining the substrate: The substrate used in Examples 1-7 and Comparative Example 1 of this invention is DC53 with a thickness of 1.2 mm.

[0069] Table 1 lists the chemical composition ratios of the substrates used in Examples 1-7 and Comparative Example 1 of this invention.

[0070] Table 1 (Balance consists of Fe and other unavoidable impurities)

[0071] (2) The substrate is subjected to hot-dip galvanizing, alloying heat treatment and flattening to form an alloyed hot-dip zinc plating layer on the substrate surface.

[0072] In some specific embodiments, the substrate can be immersed in molten zinc in a hot-dip galvanizing pot for hot-dip galvanizing, and the coating thickness can be 45 g / m. 2 Then, the steel plate is heated to 470-500℃ in a vertical heat treatment furnace for alloying heat treatment, and then held at that temperature for a certain time (specifically 4s) to allow the steel plate substrate to react and diffuse with liquid zinc, transforming into Fe-Zn intermetallic compounds, thereby forming an alloyed hot-dip galvanized layer on the substrate surface; then, a leveling roller is used for the leveling process, and the leveling rate is controlled within the range of 0.4-1.8%.

[0073] Table 2 lists the chemical composition content and process parameters of the alloyed hot-dip galvanized layer of the alloyed hot-dip galvanized steel sheets of Examples 1-7 and Comparative Example 1 of the present invention.

[0074] Table 2.

[0075] Note: The "area percentage of zinc-iron alloy crystallization region" in Table 2 was obtained by randomly selecting a 1cm section from the photograph. 2 The region was identified and its area percentage was calculated using the ImageJ image processing software.

[0076] (3) A water-based treatment agent is used to treat the surface of the alloyed hot-dip galvanized layer to obtain a composite nanostructure treatment layer.

[0077] In some specific embodiments, the water-based treatment agent includes a first substance that provides a metallic element and a second substance that provides an active group.

[0078] The first substance providing the metallic element is selected from at least one of the following: aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate, sodium aluminate, calcium nitrate, calcium acetate, calcium sulfate, zirconium acetate, zinc acetate, zinc sulfate, zinc nitrate, magnesium sulfate, magnesium citrate, magnesium lactate, zirconium borate, silver nitrate, silver sulfate, ammonium fluorozirconate, potassium fluorozirconate, and ammonium zirconium carbonate.

[0079] The second substance providing the active group is selected from at least one of the following: 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, tannic acid, cysteine, mercaptoacetic acid, mercaptoethanol, mercaptoethanol, polyethyleneimine, glycine, aspartic acid, ammonia, ethanolamine, propanolamine, isopropanolamine, ethylsilanol, and propylenesilanol.

[0080] In some embodiments, water-based treatment agents are applied by roller coating, spraying, or immersion, and then dried to form a film by sweeping or baking to prepare coiled steel.

[0081] Comparative Example 1 used the same substrate as the embodiment of the present invention and performed steps (1) and (2), but did not perform step (3).

[0082] In the water-based treatment agent, the concentration of the first substance is 1.5 wt%.

[0083] In the water-based treatment agent, the concentration of the second substance is 3.2 wt%.

[0084] Table 3 lists the composition and coating process of the water-based treatment agent for alloyed hot-dip galvanized steel sheets of Examples 1-7 and Comparative Example 1 of the present invention.

[0085] Table 3.

[0086] It should be noted that although the first substance was not used in Examples 1-7 above, it may also be selected from at least one of aluminum chloride, aluminum acetate, calcium acetate, calcium sulfate, zirconium acetate, zinc nitrate, magnesium lactate, ammonium fluorozirconate and ammonium zirconium carbonate; the second substance may also be selected from at least one of salicylic acid, tannic acid, cysteine, mercaptoacetic acid, mercaptoethanol, mercaptoethanol, glycine, propanolamine and propylenesilanol.

[0087] Table 4 lists the characteristics of the composite nanostructure treatment layer of the alloyed hot-dip galvanized steel sheets of Examples 1-7 and Comparative Example 1 of the present invention.

[0088] The equivalent sphere radius of the nanoparticles was observed and its size measured using a high-resolution scanning electron microscope (measurement plane of the largest scale orientation observed).

[0089] The proportion of needle-shaped nanoparticles to all nanoparticles is evaluated using the proportion of particles per unit area.

[0090] The weight of the surface composite nanostructure treatment layer was obtained by weighing before and after coating. The mass of the first substance was then subtracted to obtain the mass of the irregular nanostructure. The content of the two active groups was tested by detecting the nitrogen element in the amino group and the characteristic chemical bonds in the carboxyl group using X-ray photoelectron spectroscopy (XPS). The mass of the two active groups was calculated using the following formula: (mass of amino groups + mass of carboxyl groups) / mass of irregular nanostructure * 100%.

[0091] X-ray photoelectron spectroscopy (XPS) was used to detect the nitrogen element in amino groups and the characteristic chemical bonds in carboxyl groups to determine the content of the two active groups. The content was then converted to molar content and converted as a percentage.

[0092] The mass percentage of nanoparticles in the composite nanostructure treatment layer was determined by transmission electron microscopy (TEM), X-ray diffraction (XRD), and atomic absorption spectrometry (AAS), respectively, to identify the composition and volume percentage of the nanoparticles and the thin film. The mass percentage was then calculated by combining the composition density and volume percentage.

[0093] Table 4.

[0094] The alloyed hot-dip galvanized steel sheets obtained in Examples 1-7 and Comparative Example 1 were processed to a size of 100*25.4mm, and edge burrs were effectively removed. To verify the implementation effect of the embodiments of the present invention, a typical automotive structural adhesive, TEROSON EP 5089, was selected as the adhesive. The bonding sample preparation was carried out in accordance with standard SAE J1523, and the bonding area was controlled to be 3.2cm². 2The bonding thickness was controlled at 0.2 mm, the adhesive curing temperature (under harsh curing conditions) was 160℃, and the curing time was 15 min. After the adhesive cured, the bonding performance was evaluated, and the results are listed in Table 5. Among them:

[0095] Initial adhesive peel performance evaluation: After the adhesive sample has cured, it is left at room temperature for 24 hours and then subjected to a tensile peel test (refer to ASTM D 1002, tensile speed 13 mm / min), and the peel strength is recorded. The quality of the adhesive effect is evaluated by peeling method: The peeling method of the two samples after tensile peel is analyzed (peeling methods are divided into two types: cohesive peeling, i.e., internal fracture of the adhesive; interfacial peeling, i.e., separation of the adhesive from the metal surface). The adhesive performance is judged by the percentage of cohesive peeling area.

[0096] Evaluation of the rate of decline in adhesive peel strength under aging conditions: After the adhesive sample has cured, it is placed at room temperature for 24 hours and then subjected to long-term cyclic corrosion conditions (refer to PV1210). After 90 cycles, a tensile peel test is performed (refer to ASTM D 1002, tensile speed 13 mm / min), and the peel strength is recorded. The rate of decline in peel strength is calculated as follows: Adhesive peel strength decline rate = (Initial adhesive peel strength - Adhesive peel strength under aging conditions) / Initial adhesive peel strength under aging conditions * 100%.

[0097] Table 5 lists the adhesive performance evaluation results of Examples 1-7 and Comparative Example 1 of the present invention.

[0098] Table 5.

[0099] The symbols in the initial conditions for adhesive performance evaluation in Table 5 are explained as follows:

[0100] ◎: Cohesion stripping area = 100%

[0101] ○: 85% ≤ cohesive stripping area < 100%

[0102] Δ: 65% ≤ cohesive stripping area < 85%

[0103] ×: Cohesive stripping area < 65%

[0104] The symbols in the aging conditions for adhesive performance evaluation in Table 5 are explained as follows:

[0105] ◎: Adhesive peel strength attenuation rate ≤20%

[0106] ○: 20% < Adhesive peel strength attenuation rate ≤ 30%

[0107] Δ: 30% < Adhesive peel strength attenuation rate ≤ 40%

[0108] ×: 40% < Adhesive peel strength attenuation rate

[0109] As can be seen from Table 5 above, Examples 1-7 of the present invention all exhibit good performance in terms of initial adhesive peel strength and adhesive peel strength attenuation under aging conditions. Furthermore, Examples 1, 3, and 7 demonstrate that the effective composite nanostructures imparted to the surface through typical coating methods such as spraying, dipping, and roller coating all achieve good surface adhesive properties, indicating that the preparation of composite nanostructures has broader process adaptability.

[0110] As can be seen from Comparative Example 1, without the composite nanostructure treatment layer, there will be a phenomenon of poor initial adhesive peel performance and a deterioration in the rate of decrease in adhesive peel strength under aging conditions.

[0111] Figure 1 shows a schematic diagram comparing the adhesive properties of the alloyed hot-dip galvanized steel sheets of Example 1 and Comparative Example 1 according to the present invention. Fifty sets of experiments were conducted on the alloyed hot-dip galvanized steel sheets of Example 1 and Comparative Example 1 according to the method described in the initial adhesive peel strength evaluation. The obtained adhesive peel strength data were statistically analyzed to obtain Figure 1.

[0112] As shown in Figure 1, the coating of Example 1 contains 10% Fe, exhibiting good structural toughness and resistance to brittleness under shear force, thus improving coating adhesion. Simultaneously, the composite nanostructure treatment layer covering its surface strengthens the physical bonding between the adhesive and the coating interface and increases chemical bonding sites, significantly enhancing the adhesion strength of the adhesive interface. When the bonding strength between the coating and the interface exceeds the cohesive strength of the adhesive, the weak points during the tensile shear process are concentrated within the adhesive, significantly improving peel strength and stability. In contrast, the surface and adhesive of Comparative Example 1 are mainly physically adsorbed, with fewer chemical bonding points, resulting in lower bonding strength. The tensile shear fracture process is affected by three factors, reducing the adhesive peel strength and stability.

[0113] It should 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 thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. An alloyed hot-dip galvanized steel sheet with excellent surface bonding performance, comprising a substrate, wherein the surface of the substrate has an alloyed hot-dip galvanized layer; characterized in that: The surface of the alloyed hot-dip galvanized layer is covered with a composite nanostructure treatment layer; the composite nanostructure treatment layer includes nanoparticles and irregular nanostructures. The nanoparticles are randomly distributed on the surface of the alloyed hot-dip galvanized layer in at least a needle-like morphology. The irregular nanostructure has active groups that optimize the chemical bonding properties of the alloyed hot-dip galvanized layer surface.

2. The galvannealed steel sheet according to claim 1, characterized in that, The mass percentage of Fe element in the Zn-Fe alloy phase of the alloyed hot-dip galvanized layer is 8%-10%.

3. The galvannealed steel sheet according to claim 2, characterized in that, The alloyed hot-dip galvanized layer further contains Al and at least one element selected from Bi, Cd, Co, Ni and Sn; preferably, the mass percentage of Al in the alloyed hot-dip galvanized layer is 0.03%-0.2%; preferably, the total mass percentage of Bi, Cd, Co, Ni and Sn in the alloyed hot-dip galvanized layer does not exceed 0.1%.

4. The galvannealed steel sheet according to claim 1, characterized in that, The surface of the alloyed hot-dip galvanized layer has zinc-iron alloy crystalline regions and randomly distributed platform regions; preferably, the area ratio of zinc-iron alloy crystalline regions per unit area of ​​the surface is 15%-85%.

5. The alloyed hot-dip galvanized steel sheet as described in claim 1, characterized in that: The needle-like nanoparticles contain a metal-based compound, wherein the metal in the metal-based compound is selected from at least one of Na, Al, Ca, Zn, Ag, Mg, and Zr; preferably, the needle-like nanoparticles are a metal-based compound; preferably, the metal-based compound is at least one of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate, sodium aluminate, calcium nitrate, calcium acetate, calcium sulfate, zirconium acetate, zinc acetate, zinc sulfate, zinc nitrate, magnesium sulfate, magnesium citrate, magnesium lactate, zirconium borate, silver nitrate, silver sulfate, ammonium fluorozirconate, potassium fluorozirconate, and ammonium zirconium carbonate; and / or Within a unit area of ​​the surface, the needle-like nanoparticles account for 20%-70% of the total number of nanoparticles; and / or The equivalent sphere radius of the nanoparticles is 30-200 nm.

6. The alloyed hot-dip galvanized steel sheet as described in claim 1, characterized in that: The active groups constitute 6%-70% of the mass of the irregular nanostructure; and / or, The active group includes an amino group and a carboxyl group; preferably, the active group is provided by at least one selected from 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, tannic acid, cysteine, mercaptoacetic acid, mercaptoethanol, mercaptoethanol, polyethyleneimine, glycine, aspartic acid, ammonia, ethanolamine, propanolamine, isopropanolamine, ethylsilanol, and propylenesilanol.

7. The galvannealed steel sheet according to claim 6, characterized in that, The molar percentage of the amino groups to the carboxyl groups is 10%-150%.

8. The alloyed hot-dip galvanized steel sheet as described in claim 1, characterized in that: The nanoparticles constitute 20%-60% of the mass percentage in the composite nanostructure treatment layer; and / or, The irregular nanostructures account for 40% to 80% of the mass percentage of the composite nanostructure treatment layer; and / or, The thickness of the composite nanostructure treatment layer is 10-100 g / m 2 .

9. The galvannealed steel sheet according to claim 1, characterized in that: The composite nanostructure treatment layer contains: (1) at least one of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate, sodium metaaluminate, calcium nitrate, calcium acetate, calcium sulfate, zirconium acetate, zinc acetate, zinc sulfate, zinc nitrate, magnesium sulfate, magnesium citrate, magnesium lactate, zirconium borate, silver nitrate, silver sulfate, ammonium fluozirconate, potassium fluozirconate, and zirconium carbonate, preferably one or more of aluminum nitrate, zirconium borate, magnesium sulfate, calcium nitrate, sodium metaaluminate, magnesium citrate, zinc acetate, silver nitrate, potassium fluozirconate, aluminum sulfate, and silver sulfate; and (2) at least one of 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, tannic acid, cysteine, mercaptoacetic acid, mercaptomethanol, mercaptoethanol, polyethyleneimine, glycine, aspartic acid, ammonia, ethanolamine, propanolamine, isopropanolamine, ethylsilanol, and propenylsilanol, preferably one or more of 3,4,5-trihydroxybenzoic acid, ammonia, tartaric acid, isopropanolamine, ethylsilanol, aspartic acid, oxalic acid, ethylsilanol, ethanolamine, polyethyleneimine, citric acid, and ethylenediaminetetraacetic acid.

10. The galvannealed steel sheet according to claim 1, characterized in that: The composite nanostructure treatment layer is prepared by a method of coating and drying a water-based treatment agent including a first substance and a second substance; wherein the first substance is selected from at least one of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate, sodium metaaluminate, calcium nitrate, calcium acetate, calcium sulfate, zirconium acetate, zinc acetate, zinc sulfate, zinc nitrate, magnesium sulfate, magnesium citrate, magnesium lactate, zirconium borate, silver nitrate, silver sulfate, ammonium fluozirconate, potassium fluozirconate, and zirconium carbonate; and the second substance is selected from at least one of 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, tannic acid, cysteine, mercaptoacetic acid, mercaptomethanol, mercaptoethanol, polyethyleneimine, glycine, aspartic acid, ammonia, ethanolamine, propanolamine, isopropanolamine, ethylsilanol, and propenylsilanol; Preferably, the concentration of the first substance in the water-based treatment agent is 0.5wt% to 6wt%; Preferably, the concentration of the second substance in the water-based treatment agent is 1wt% to 8wt%; Preferably, the mass ratio of the first substance to the second substance in the water-based treatment agent is 1:1 to 1:

15.

11. The method of producing a galvannealed steel sheet according to any one of claims 1 to 10, characterized in that, The steps include: carrying out hot-dip plating, alloying heat treatment, and leveling on the substrate to form the alloyed hot-dip galvanized layer on the surface of the substrate; carrying out surface treatment on the alloyed hot-dip galvanized layer with a water-based treatment agent to obtain the composite nanostructure treatment layer.

12. The production method according to claim 11, wherein The water-based treatment agent includes a first substance providing a metal-based compound and a second substance providing an active group, and the mass ratio of the first substance to the second substance is 1:1 to 1:

15.

13. The production method according to claim 11, wherein The first substance is selected from at least one of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate, sodium metaaluminate, calcium nitrate, calcium acetate, calcium sulfate, zirconium acetate, zinc acetate, zinc sulfate, zinc nitrate, magnesium sulfate, magnesium citrate, magnesium lactate, zirconium borate, silver nitrate, silver sulfate, ammonium fluorozirconate, potassium fluorozirconate, and ammonium zirconium carbonate; and / or the second substance is selected from at least one of 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, tannic acid, cysteine, mercaptoacetic acid, mercaptomethanol, mercaptoethanol, polyethyleneimine, glycine, aspartic acid, ammonia, ethanolamine, propanolamine, isopropanolamine, ethylsilanol, and propenylsilanol; and / or the concentration of the first substance in the water-based treatment agent is 0.5wt% to 6wt%; and / or the concentration of the second substance in the water-based treatment agent is 1wt% to 8wt%.

14. The manufacturing method according to claim 11, wherein: the temperature of the alloying heat treatment is 470-500°C; and / or the water-based treatment agent is applied to the galvannealing layer by roll coating, spraying, or dip coating, and then dried by blowing or baking; and / or the flatness of the flatness is 0.4-1.8%.

15. A treatment agent comprising a first substance and a second substance, wherein the first substance and the second substance are as defined in claim 12; preferably, the mass ratio of the first substance to the second substance is 1:1 to 1:15; preferably, the treatment agent is a water-based treatment agent; preferably, the concentration of the first substance in the water-based treatment agent is 0.5wt% to 6wt%; and / or, the concentration of the second substance in the water-based treatment agent is 1wt% to 8wt%. ​

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