Scratch-resistant aluminum-iron alloying coated steel plate and manufacturing method thereof

Abstract

The invention belongs to the technical field of aluminum-iron plated steel plates, and particularly relates to a scratch-resistant aluminum-iron alloyed plated steel plate and a manufacturing method and application thereof. The scratch-resistant aluminum-iron alloying coated steel plate comprises a base plate, a diffusion layer, an Al-Fe phase containing Co and / or W, an Al-Fe-Si phase containing Co and / or W and an Al2O3 oxidation film multilayer structure, the base plate is subjected to hot dipping to form an aluminum-silicon alloy coating on the surface, and then the aluminum-silicon alloy coating is converted into an aluminum-iron alloy coating after alloying annealing and Fe element diffusion; the total thickness of the aluminum-iron alloy coating is 6-45 microns, the thickness of the diffusion layer is 1-10 microns, the thickness of the Al2O3 oxidation film is 0.1-1 micron, the Al-Fe-Si phase containing Co and / or W accounts for 10%-40% of the sectional area of the aluminum-iron alloy coating, the rest is the Al-Fe phase containing Co and / or W, and the surface of the aluminum-iron alloy coating is black. The hardness of the plating layer of the steel plate can reach 180 HV or above.

Description

Technical Field

[0001] This invention belongs to the technical field of aluminum-iron coated steel sheets, and specifically relates to a scratch-resistant aluminum-iron alloy coated steel sheet, its manufacturing method, and its application. Background Technology

[0002] In industrial sectors such as automotive, home appliances, and construction, materials not only need excellent high-temperature resistance and corrosion resistance, but also outstanding wear and scratch resistance to cope with complex and ever-changing operating environments. Coated steel sheets are widely used in these industries due to their superior corrosion resistance and processing performance. However, traditional galvanized steel sheets have significant shortcomings in wear and scratch resistance, especially under high-temperature, high-frequency contact or friction conditions, where scratches and wear easily appear on the coating surface, affecting the material's appearance and performance. Therefore, developing a coated steel sheet that possesses both good corrosion resistance and excellent scratch resistance at high temperatures is particularly important. This invention aims to provide a scratch-resistant aluminum-iron alloy coated steel sheet. By adding alloying elements such as Co and W, not only are numerous nucleation sites provided, refining the grain size, but Co and / or W also play a solid solution strengthening role in the coating structure, significantly improving the coating hardness and thus enhancing its wear and scratch resistance, while maintaining good corrosion resistance and processing performance to meet the higher requirements of high-end manufacturing for comprehensive material performance.

[0003] Patent CN202221821363.8 describes a scratch-resistant reflective film, which includes a wear-resistant protective layer, a reflective layer, and an adhesive layer. The scratch-resistant layer of the reflective film is made of highly elastic transparent PU material, while the coating involved in this patent is an aluminum-iron alloy coating.

[0004] Patent CN202411806340.3 discloses a steel strip with a high wear-resistant coating and its processing technology, relating to the field of stainless steel strip technology. While the previous patent used stainless steel strip as the substrate and plated it with a nickel layer, this patent uses cold-formed steel as the substrate and the coating is an aluminum-iron alloy coating. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a scratch-resistant aluminum-iron alloy coated steel sheet and its manufacturing method. Co and W elements are added to the hot-dip galvanized coating, and then alloying annealing treatment is performed to obtain an aluminum-iron coated steel sheet with excellent scratch resistance, heat resistance and corrosion resistance, and a black appearance that can be applied without secondary painting.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A scratch-resistant aluminum-iron alloy coated steel sheet includes a substrate, a diffusion layer, an Al-Fe phase containing Co and / or W, an Al-Fe-Si phase containing Co and / or W, and an Al2O3 oxide film multilayer structure. The substrate is first hot-dip coated to form an aluminum-silicon alloy coating, and then alloyed and annealed. After Fe element diffusion, the aluminum-silicon alloy coating is transformed into an aluminum-iron alloy coating. The total thickness of the aluminum-iron alloy coating is 6-45 μm, of which the diffusion layer thickness is 1-10 μm, the Al2O3 oxide film thickness is 0.1-1 μm, the Al-Fe-Si phase containing Co and / or W accounts for 10%-40% of the cross-sectional area of ​​the aluminum-iron alloy coating, and the remainder is the Al-Fe phase containing Co and / or W. The surface of the aluminum-iron alloy coating is black.

[0008] The aluminum-silicon alloy coating has the following chemical composition by weight percentage: Si: 0.5%–15%, Fe: 1.0%–2.5%, Co: 0 or 0.1%–1.0%, W: 0 or 0.1%–1.0%, where Co and W cannot both be 0; the remainder is Al and unavoidable impurities.

[0009] The total thickness of the aluminum-silicon alloy coating is 5–35 μm, of which the thickness of the diffusion layer is 0.5–6 μm.

[0010] The chemical composition of the substrate, by mass percentage, includes: C: 0.01%–0.35%, Si: 0.02%–0.70%, Mn: 0.20%–1.50%, P≤0.07%, S≤0.05%, Al: 0.02%–1.00%, Ti≤0.07%, and Fe and unavoidable impurities.

[0011] A method for manufacturing a scratch-resistant aluminum-iron alloy coated steel sheet, comprising the following steps: smelting, casting, hot rolling, pickling, cold rolling, continuous hot-dip galvanizing, alloying annealing, cooling, leveling, and packaging; specifically including:

[0012] 1) The hot rolling process is as follows: heating at 1220~1260℃, holding at 175~215min, rough rolling at 1080~1120℃, finish rolling at 1030~1150℃, final rolling at 860~900℃, and coiling at 460~750℃.

[0013] 2) The cold rolling process is as follows: compression ratio 50%~85%; surface roughness 0.6~1.5; hydrochloric acid concentration in pickling solution 10~20%; pickling temperature 70~95℃; pickling speed 60~200m / min.

[0014] 3) The continuous hot-dip galvanizing process is as follows: heating and annealing temperature is 720~900℃, steel plate temperature in aluminum pot is 635~690℃, and aluminum pot temperature is 630~685℃.

[0015] 4) The alloying annealing process is as follows: annealing is carried out in a bell-type furnace, and the atmosphere in the furnace can be one of H2, N2, N2+O2, or N2+water vapor.

[0016] The target heating temperature is 590–730℃, and the heating process is divided into three stages:

[0017] The first stage is the rapid heating stage, which raises the temperature from room temperature to 400℃ at a rate of 50-500℃ / h.

[0018] The second stage is a slow heating stage, from 400℃ to 550℃, with a heating rate of 1~18℃ / h.

[0019] The third stage is a relatively rapid heating stage, where the temperature is increased from 550℃ to the target temperature at a rate of 20-100℃ / h. The relatively rapid heating can prevent excessive grain growth, refine the coating structure, and improve the density of the coating surface.

[0020] After heating to the target temperature, maintain the temperature for 2–8 hours.

[0021] 5) Cooling after alloying annealing can be divided into two stages:

[0022] The first stage is a slow cooling stage, where the target temperature is slowly cooled to 400℃ at a cooling rate of 10-100℃ / h.

[0023] The second stage is the natural cooling stage, where the temperature naturally cools from 400℃ to room temperature.

[0024] 6) The leveling process is as follows: the elongation rate is controlled between 0.5% and 2.0%. After leveling, the steel plate is packaged as a finished product.

[0025] In step 4), when the atmosphere inside the furnace is N2+O2, the volume content of O2 is less than 2%, and when the atmosphere inside the furnace is N2+water vapor, the volume content of water vapor is less than 4%.

[0026] The scratch-resistant aluminum-iron alloy coated steel sheet is used for cold forming.

[0027] Compared with existing technologies, the beneficial effects of this invention are:

[0028] 1. The aluminum-iron alloy coated steel sheet has added Co and / or W elements, and the coating hardness can reach more than 180HV, thereby enhancing its wear resistance and scratch resistance.

[0029] 2. This aluminum-iron alloy coated steel sheet has good heat resistance and corrosion resistance, and can work stably in high-temperature environments.

[0030] 3. After alloying annealing, the coating surface is black, which can meet the aesthetic requirements without secondary coating.

[0031] 4. The black exterior has a high heat absorption rate (low reflectivity), making it suitable for components that require rapid heat absorption or dissipation, thus improving thermal energy utilization efficiency.

[0032] 5. The coated steel sheet can be processed by cold forming methods such as stamping and bending. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the steel plate structure of the present invention.

[0034] In the figure: 1. Substrate; 2. Diffusion layer; 3. Al-Fe phase containing Co and / or W; 4. Al-Fe-Si phase containing Co and / or W; 5. Al2O3 oxide film. Detailed Implementation

[0035] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. The reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0036] A scratch-resistant aluminum-iron alloy coated steel sheet includes a substrate 1, a diffusion layer 2, an Al-Fe phase containing Co and / or W 3, an Al-Fe-Si phase containing Co and / or W 4, and an Al2O3 oxide film 5, comprising a multilayer structure (see...). Figure 1 The substrate 1 is first hot-dip coated to form an aluminum-silicon alloy coating, and then alloyed and annealed. After Fe element diffusion, the aluminum-silicon alloy coating is transformed into an aluminum-iron alloy coating. The total thickness of the aluminum-iron alloy coating is 6-45 μm, of which the thickness of the diffusion layer 2 is 1-10 μm, the thickness of the Al2O3 oxide film is 0.1-1 μm, the proportion of Al-Fe-Si phase containing Co and / or W in the cross-sectional area of ​​the aluminum-iron alloy coating is 10%-40%, and the remainder is Al-Fe phase containing Co and / or W. The surface of the aluminum-iron alloy coating is black.

[0037] The aluminum-silicon alloy coating has the following chemical composition by weight percentage: Si: 0.5%–15%, Fe: 1.0%–2.5%, Co: 0 or 0.1%–1.0%, W: 0 or 0.1%–1.0%, where Co and W cannot both be 0; the remainder is Al and unavoidable impurities.

[0038] The total thickness of the aluminum-silicon alloy coating is 5–35 μm, wherein the thickness of the diffusion layer 2 is 0.5–6 μm.

[0039] The chemical composition of the substrate 1, by mass percentage, includes: C: 0.01%–0.35%, Si: 0.02%–0.70%, Mn: 0.20%–1.50%, P≤0.07%, S≤0.05%, Al: 0.02%–1.00%, Ti≤0.07%, and Fe and unavoidable impurities.

[0040] The role of elements in the coating:

[0041] Adding Co and / or W to aluminum-silicon alloy coatings not only provides a large number of nucleation sites that refine the grains, but also Co and / or W play a solid solution strengthening role in the coating structure, which can significantly improve the coating hardness and thus enhance its wear resistance and scratch resistance.

[0042] A method for manufacturing a scratch-resistant aluminum-iron alloy coated steel sheet, comprising the following steps: smelting, casting, hot rolling, pickling, cold rolling, continuous hot-dip galvanizing, alloying annealing, cooling, leveling, and packaging; specifically including:

[0043] 1) The hot rolling process is as follows: heating at 1220~1260℃, holding at 175~215min, rough rolling at 1080~1120℃, finish rolling at 1030~1150℃, final rolling at 860~900℃, and coiling at 460~750℃.

[0044] 2) The cold rolling process is as follows: compression ratio 50%~85%; surface roughness 0.6~1.5; hydrochloric acid concentration in pickling solution 10~20%; pickling temperature 70~95℃; pickling speed 60~200m / min.

[0045] 3) The continuous hot-dip galvanizing process is as follows: heating and annealing temperature is 720~900℃, steel plate temperature in aluminum pot is 635~690℃, and aluminum pot temperature is 630~685℃.

[0046] 4) The alloying annealing process is as follows: annealing is carried out in a bell-type furnace, and the furnace atmosphere can be one of the following four: H2, N2, N2+O2, or N2+water vapor. When the furnace atmosphere is N2+O2, the O2 volume content is less than 2%. When the furnace atmosphere is N2+water vapor, the water vapor volume content is less than 4%.

[0047] The target heating temperature is 590–730℃, and the heating process is divided into three stages:

[0048] The first stage is a slow cooling stage, in which the target temperature is slowly cooled to 400°C at a rate of 20–80°C / h. This slow cooling process can effectively prevent the formation of cracks caused by the difference in thermal expansion coefficients between the substrate and the coating.

[0049] The second stage is the slow heating stage, which involves heating from 400℃ to 550℃ at a rate of 1 to 18℃ / h. The slow heating can prevent the rapid growth of the diffusion layer, provide more nucleation sites, and refine the grains.

[0050] The third stage is a relatively rapid heating stage, where the temperature is increased from 550℃ to the target temperature at a rate of 20-100℃ / h. The relatively rapid heating can prevent excessive grain growth, refine the coating structure, and improve the density of the coating surface.

[0051] After heating to the target temperature, maintain the temperature for 2–8 hours.

[0052] 5) After alloying annealing, cooling is performed. The cooling process can be divided into two stages:

[0053] The first stage is the slow cooling stage, which involves slowly cooling the target temperature to 400℃ at a rate of 10-100℃ / h. This slow cooling process can effectively prevent plate shape defects caused by differences in thermal stress at different locations of the steel coil.

[0054] The second stage is the natural cooling stage, where the temperature naturally cools from 400℃ to room temperature.

[0055] The annealing temperature should not be too high or too low, and the annealing time should not be too long or too short. When the annealing temperature is too high or the time is too long, the diffusion between Al and Fe intensifies, which leads to the coating becoming brittle and the surface exhibiting powdering and cracking. When the annealing temperature is too low or the time is too short, the diffusion between Al and Fe is insufficient, resulting in incomplete alloying, uneven surface color, and insufficient blackening of the coating.

[0056] 6) The leveling process is as follows: the elongation rate is controlled between 0.5% and 2.0%. After leveling, the steel plate is packaged as a finished product.

[0057] The aluminum-iron alloy coated steel sheet can be processed by cold forming methods such as stamping and bending.

[0058] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0059] The chemical composition of the aluminum-silicon alloy coating after hot-dip plating of the substrate provided in the embodiments is shown in Table 1.

[0060] The substrate provided in the embodiment is a cold-formed stamped steel sheet, and the chemical composition of the substrate is shown in Table 2.

[0061] The steel plate provided in the embodiment is first hot rolled and then cold rolled. The hot rolling process is shown in Table 3, and the cold rolling process is shown in Table 4.

[0062] The cold-rolled steel sheet provided in the embodiment was subjected to hot-dip aluminizing and silicon coating. The hot-dip coating process is shown in Table 5.

[0063] The hot-dip aluminized silicon alloy coated steel sheet provided in the embodiment was subjected to alloying annealing treatment. The alloying annealing process is shown in Table 6.

[0064] The proportion of Al-Fe-Si phase in the coating was calculated and analyzed using Proimage software. The coating analysis results are shown in Table 7.

[0065] After alloying annealing, observe whether the coating surface is powdery; conduct a reverse impact test according to GB / T13448-2019 standard to test its adhesion; use a micro Vickers hardness tester to test the hardness of the coating, and use a loading force of HV0.02 to test the hardness of the coating; use a friction and wear tester to analyze the wear resistance of the coating, with a constant force of 100N perpendicular to the steel plate surface and sliding 50mm along the material surface in one direction for 100s. The coating properties after alloying annealing are shown in Table 8.

[0066] To test the state and changes of aluminum-iron alloy coated steel sheets at high temperatures, the aluminum-iron alloy coated steel sheets were placed in an oven, kept at high temperature and then cooled naturally. The coating surface was then observed again to see if powder was being removed. The reverse impact adhesion, coating hardness, and wear resistance were measured. The test results are shown in Table 9.

[0067] Table 1. Composition of aluminum-silicon alloy coating, wt%

[0068]

[0069] Table 2 Substrate composition, wt%

[0070]

[0071] Table 3 Hot Rolling Process

[0072]

[0073] Table 4 Cold Rolling Process

[0074]

[0075] Table 5 Hot-dip galvanizing process

[0076]

[0077] Table 6 Alloying Annealing Process

[0078]

[0079] Table 7. Composition of the coating after alloying annealing

[0080]

[0081] Table 8. Coating properties after alloying annealing

[0082]

[0083] Table 9. Coating properties after high-temperature baking

[0084]

[0085] The scratch-resistant aluminum-iron alloy coated steel sheet provided in the embodiments is used for cold-formed house flues, equipment control panels, and kitchen appliance oven and microwave oven housings.

[0086] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A scratch-resistant, aluminum-iron alloyed plated steel sheet, characterized by, The multilayer structure comprises a substrate, a diffusion layer, an Al-Fe phase containing Co and / or W, an Al-Fe-Si phase containing Co and / or W, and an Al2O3 oxide film, wherein the substrate is first coated with an Al-Si alloy layer by hot-dip plating, and then the Al-Si alloy layer is converted into an Al-Fe alloy layer by diffusion of Fe element after alloying annealing; the total thickness of the Al-Fe alloy layer is 6-45 microns, wherein the thickness of the diffusion layer is 1-10 microns, the thickness of the Al2O3 oxide film is 0.1-1 micron, the proportion of the Al-Fe-Si phase containing Co and / or W in the cross-sectional area of the Al-Fe alloy layer is 10%-40%, and the rest is the Al-Fe phase containing Co and / or W, and the surface of the Al-Fe alloy layer is black.

2. The scratch-resistant, aluminum-iron alloyed coated steel sheet according to claim 1, characterized in that, The Al-Si alloy layer has a chemical composition comprising, by weight percentage, Si: 0.5%-15%, Fe: 1.0%-2.5%, Co: 0 or 0.1-1.0%, W: 0 or 0.1-1.0%, and Co and W cannot be 0 at the same time; and the rest is Al and inevitable impurities.

3. The scratch-resistant, aluminum-iron alloyed coated steel sheet according to claim 1, characterized in that, The total thickness of the Al-Si alloy layer is 5-35 microns, wherein the thickness of the diffusion layer is 0.5-6 microns.

4. The scratch-resistant, aluminum-iron alloyed coated steel sheet according to claim 1, characterized in that, The substrate has a chemical composition comprising, by mass percentage, C: 0.01%-0.35%, Si: 0.02%-0.70%, Mn: 0.20%-1.50%, P≤0.07%, S≤0.05%, Al: 0.02%-1.00%, Ti≤0.07%, and Fe and inevitable impurities.

5. The manufacturing method of the scratch-resistant Al-Fe alloyed plated steel sheet according to claim 1, wherein the process steps comprise smelting, casting, hot rolling, pickling, cold rolling, continuous hot-dip plating, alloying annealing, cooling, flattening, and packaging; and the specific steps comprise: 1) the hot rolling process is heating at 1220-1260℃, holding for 175-215 min, rough rolling at 1080-1120℃, finish rolling at 1030-1150℃, final rolling at 860-900℃, and coiling at 460-750℃; 2) the cold rolling process is: compression ratio 50%-85%; surface roughness 0.6-1.5; hydrochloric acid concentration in pickling solution 10-20%; pickling temperature 70-95℃; and pickling speed 60-200 m / min. 3) the continuous hot-dip plating process is: heating annealing temperature 720-900℃, steel sheet entering aluminum pot temperature 635-690℃, and aluminum pot temperature 630-685℃. 4) the alloying annealing process is carried out in a bell-type furnace, and the furnace atmosphere can be one of H2, N2, N2+O2, and N2+water vapor; the heating target temperature is 590-730℃, and the heating process is divided into three stages: the first stage is a rapid heating stage, from room temperature to 400℃ at a heating rate of 50-500℃ / h; the second stage is a slow heating stage, from 400℃ to 550℃ at a heating rate of 1-18℃ / h; The third stage is a faster heating stage, heating from 550℃ to the target temperature at a heating rate of 20-100℃ / h, which can hinder the grain from growing too much, refine the coating structure and improve the density of the coating surface. After heating to the target temperature, the temperature is kept for 2-8h. 5) After alloying annealing, the cooling process can be divided into two stages: The first stage is a slow cooling stage, slowly cooling from the target temperature to 400℃ at a cooling rate of 10-100℃ / h; The second stage is a natural cooling stage, naturally cooling from 400℃ to room temperature; 6) The leveling process is: the elongation is controlled at 0.5-2.0%, and the leveled steel plate is packaged as a finished product.

6. The method of manufacturing a scratch-resistant aluminum iron alloy coated steel sheet according to claim 5, characterized in that, In step 4), when the furnace atmosphere is N2+O2, the volume content of O2 is less than 2%, and when the furnace atmosphere is N2+water vapor, the volume content of water vapor is less than 4%.

7. The scratch-resistant aluminum-iron alloyed coated steel sheet according to any one of claims 1-4 for processing in a cold forming mode.

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