Aluminum-plated steel plate, member, and preparation method therefor

Abstract

An aluminum-plated steel plate, which comprises: a substrate, an aluminum-containing plating and a zinc-containing layer. The aluminum-containing plating is adhered onto the substrate, and the zinc-containing layer is adhered onto the side of the aluminum-containing plating away from the substrate. The zinc-containing layer comprises a zinc-containing alloy layer and / or a zinc-containing oxide layer.

Description

Aluminized steel sheet, component and its preparation method Cross-reference to related applications

[0001] This application claims priority to Chinese patent application No. 202411459532.1, filed on October 18, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of aluminized steel sheet technology, and in particular to an aluminized steel sheet, a component and a method for preparing the same. Background Technology

[0003] Currently, high-strength and ultra-high-strength steel sheets are of great significance for the lightweighting of automobile bodies. However, as the required strength of steel for automobile bodies continues to increase, the plasticity of the steel used in automobile bodies has decreased significantly, and the forming performance has also decreased significantly. In particular, cracking and springback are prone to occur during the cold forming process of steel, which seriously affects the shape and dimensional accuracy of cold stamped components.

[0004] Hot stamping technology utilizes the characteristic that steel sheets have increased plasticity and decreased forming resistance at high temperatures. It involves heating a steel sheet blank with relatively low initial strength, then rapidly stamping it into shape within a mold equipped with a cooling system, followed by quenching and cooling. This process yields ultra-high strength hot-stamped components, effectively solving problems such as cracking and severe springback that occur during cold forming. As a method for forming ultra-high strength components, hot stamping requires heating the steel sheet in the atmosphere or a protective gas atmosphere.

[0005] In related technologies, aluminum alloy coated steel is a type of steel with an aluminum alloy coating on a substrate. The aluminum alloy coating offers excellent corrosion resistance, and due to the high melting point of aluminum, rapid interdiffusion occurs between the coating and the substrate at high temperatures, forming high-melting-point intermetallic compounds, Fe-Al and / or Fe-Al-Si phases. This effectively solves the problem of excessive surface oxide scale formation in hot-stamped components without aluminum alloy coatings during heating, extending mold life and improving production efficiency. However, the high hardness of the Fe-Al and / or Fe-Al-Si phases can easily cause roughening or damage to the mold. Furthermore, the surface of hot-stamped components made of aluminum alloy coated steel cannot undergo normal phosphating; the adhesion of the electrophoretic coating relies entirely on the high roughness of the aluminum alloy coating, leading to a risk that the paint adhesion of the aluminum alloy coated steel may not meet usage requirements. Summary of the Invention

[0006] By utilizing one or more embodiments of the present disclosure, the problem of roughening or damage to the mold caused by aluminum alloy coated steel during hot stamping is solved to a certain extent in the related art. At the same time, the problem of poor paint film adhesion of aluminum alloy coated steel is also solved to a certain extent.

[0007] In a first aspect, an aluminized steel sheet according to some embodiments of the present disclosure includes a substrate, an aluminum-containing coating, and a zinc-containing layer, wherein the aluminum-containing coating is attached to the substrate, the zinc-containing layer is attached to the side of the aluminum-containing coating away from the substrate, and the zinc-containing layer includes a zinc-containing alloy layer and / or a zinc-containing oxide layer.

[0008] Secondly, according to some embodiments of the present disclosure, a method for preparing an aluminized steel sheet includes: rolling a steel billet to obtain a substrate; immersing the substrate in an aluminum-containing plating solution for aluminum plating treatment to form an aluminum-containing coating; and spraying zinc-containing particles during the solidification process of the aluminum-containing plating solution to form a zinc-containing layer, thereby obtaining the aluminized steel sheet; wherein the zinc-containing layer includes a zinc-containing alloy layer and / or a zinc-containing oxide layer.

[0009] Thirdly, according to some embodiments of the present disclosure, the material of the component includes the aforementioned aluminized steel sheet.

[0010] Fourthly, a method for preparing a component according to some embodiments of the present disclosure includes: obtaining the above-mentioned aluminized steel sheet; heat-treating the aluminized steel sheet; and stamping the heat-treated aluminized steel sheet to obtain the component. Attached Figure Description

[0011] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0012] To more clearly illustrate the technical solutions in the embodiments or related technologies of this disclosure, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0013] Figure 1 shows a schematic flowchart of a method for preparing an aluminized steel sheet according to some embodiments of the present disclosure;

[0014] Figure 2 shows a schematic diagram of the process of spraying zinc-containing particles in the preparation method of aluminized steel sheet according to some embodiments of the present disclosure;

[0015] Figure 3 shows the zinc distribution on the surface of the aluminized steel sheet before hot stamping in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure;

[0016] Figure 4 shows the zinc distribution on the surface of the part after hot stamping of the aluminized steel sheet in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure;

[0017] Figure 5 shows a SEM image of the zinc-containing layer of the aluminized steel sheet after hot stamping in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure;

[0018] Figure 6 shows the energy spectrum of the zinc-containing layer after hot stamping of the aluminized steel sheet in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure;

[0019] Figure 7 shows a comparison of the GDS of the aluminized steel sheet before and after hot stamping in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure;

[0020] Figure 8 shows the surface morphology of the phosphate film on the aluminized steel sheet after heat treatment in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure.

[0021] Figure 9 shows the energy spectrum of the phosphate film after heat treatment of the aluminized steel sheet in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure;

[0022] Figure 10 shows the surface P signal diagram of the aluminized steel sheet after phosphating in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure;

[0023] Figure 11 shows the surface P signal diagram of the aluminized steel sheet after phosphating in the preparation method of the aluminized steel sheet according to Comparative Example 1 of this disclosure. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0025] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this disclosure are available on the market or can be prepared by existing methods.

[0026] In related technologies, aluminum alloy coated steel is a type of steel with an aluminum alloy coating on a substrate. The aluminum alloy coating has excellent corrosion resistance, and due to the high melting point of aluminum, rapid interdiffusion can occur between the aluminum alloy coating and the substrate at high temperatures, thereby forming high-melting-point intermetallic compounds Fe-Al phase and / or Fe-Al-Si phase. Therefore, it can effectively solve the problem of large amounts of surface oxide scale easily generated in uncoated steel plates during heating, which can extend the service life of molds and improve production efficiency.

[0027] In the coating process of aluminum alloy coated steel, the first step is to perform pretreatment, that is, to form a chemical conversion film on the surface of the aluminum alloy coated steel, so as to improve the adhesion, corrosion resistance and inter-process corrosion prevention of the paint film of electrophoretic coating. At present, phosphating is a relatively mature and widely used pretreatment technology. However, due to the following reasons, the phosphating performance of aluminum alloy coated steel is poor: (1) The aluminum alloy coating after degreasing is easily oxidized and easily forms a dense oxide film. At the same time, oxidants are added to the phosphating solution, which further promotes the formation of a dense oxide film; (2) Compared with phosphating film-forming substances such as zinc phosphate and zinc ferric phosphate, the phosphating film-forming substance of aluminum alloy coating is mainly aluminum phosphate. Since aluminum phosphate is more likely to precipitate, that is, aluminum phosphate is more likely to form sludge rather than a phosphating film. Therefore, the adhesion of the paint film prepared after hot stamping of aluminum alloy coated steel components depends entirely on the uneven structure of the component surface.

[0028] This disclosure aims to provide an aluminized steel sheet, components, and a method for preparing the same. By spraying zinc-containing particles onto the surface of an aluminum-containing coating (which may be an aluminum-silicon alloy coating) attached to a substrate to form a zinc-containing layer including a zinc-containing alloy layer and / or a zinc-containing oxide layer, the hot-formability of the aluminized steel sheet and the coating performance and corrosion resistance of its hot-stamped components can be improved. This results in components with a lower coefficient of friction, better coating performance, and better corrosion resistance, making them suitable for automotive safety components, such as front / rear door anti-collision beams, bumpers, A / B pillar reinforcement plates, floor center tunnels, and other safety components.

[0029] According to some embodiments of the present disclosure, an aluminized steel sheet includes a substrate, an aluminum-containing coating, and a zinc-containing layer. The aluminum-containing coating is attached to the substrate, and the zinc-containing layer is attached to the side of the aluminum-containing coating away from the substrate. The zinc-containing layer includes a zinc-containing alloy layer and / or a zinc-containing oxide layer.

[0030] This aluminized steel sheet, by setting a zinc-containing layer including a zinc-containing alloy layer and / or a zinc-containing oxide layer on the aluminum-containing coating, can reduce the coefficient of friction during the hot stamping process, thereby avoiding problems such as scratching or mold damage during the hot stamping process. At the same time, it can also improve the phosphating performance of the aluminized steel sheet, which is beneficial to the corrosion resistance and adhesion of the subsequent electrophoretic coating film, and helps to improve the adhesion of the paint film.

[0031] The mechanism by which a zinc-containing layer, including a zinc-containing alloy layer and / or a zinc-containing oxide layer, is applied to the side of the aluminum-containing coating away from the substrate can improve the coating performance of galvanized steel sheets is as follows: Phosphoric acid in the phosphating solution can dissociate to form H... + and PO4 3～When an aluminized steel sheet with a zinc-containing layer is immersed in a phosphating solution, the zinc is etched by acid to form Zn. 2+ Meanwhile, H + The consumption of Zn leads to a local increase in the pH value of the phosphating solution, causing Zn to be consumed. 2+ PO4 3～ Once the film-forming material reaches saturation, a phosphating film mainly composed of Zn3(PO4)2·4H2O is formed. The chemical reaction process is as follows:

[0032] Phosphoric acid dissociation:

[0033] Acid etching of zinc:

[0034] Phosphate film deposition: 3Zn 2+ +2PO4 3- +4H2O→Zn3(PO4)2·4H2O(3)

[0035] Meanwhile, even if the zinc in the zinc-containing layer is oxidized to zinc oxide during heat treatment, a phosphating film mainly composed of Zn3(PO4)2·4H2O will be formed under the action of phosphoric acid in the phosphating solution. The chemical reaction process is as follows:

[0036] Phosphate film deposition: 3ZnO + 2H3PO4 + H2O → Zn3(PO4)2·4H2O (4)

[0037] As can be seen, compared with the aluminum alloy coated steel in related technologies, the aluminum-coated steel sheet of this disclosure has a zinc-containing layer attached to the side of the aluminum coating away from the substrate. The zinc-containing layer includes a zinc-containing alloy layer and / or a zinc-containing oxide layer. Since Zn or ZnO is relatively easy to phosphate, it can improve the phosphate performance of the aluminum-coated steel sheet to a certain extent, which is beneficial to improving the corrosion resistance and adhesion of the subsequent electrophoretic coating process and improving the adhesion of the paint film.

[0038] In some embodiments, a diffusion bonding layer exists between the zinc-containing layer and the aluminum-containing coating. The zinc-containing layer is prepared by spraying zinc-containing particles during the preparation of the aluminum-containing coating (i.e., before the aluminum plating solution solidifies). During this process, zinc diffuses to form a diffusion bonding layer, which helps to improve the adhesion between the zinc-containing layer and the aluminum-containing coating.

[0039] In some embodiments, the area coverage of the zinc-containing layer on one side of the aluminized steel sheet is ≥80%, with a zinc content greater than 0.5% by mass; the depth of the zinc-containing layer ranges from 0.4 μm to 29 μm; and the zinc content of the zinc-containing layer is 0.1 g / m². 2 ~8g / m 2 .

[0040] In some embodiments, the aluminum-containing coating includes an alloy coating containing an Al-Fe-Si system.

[0041] In some embodiments, the aluminum-containing coating comprises a variety of alloy phases and intermetallic compound phases.

[0042] In some embodiments, the thickness of the aluminum-containing coating is 4 μm to 50 μm.

[0043] In some embodiments, the single-sided loading of the aluminum-containing coating is 10 g / m². 2 ~100g / m 2 .

[0044] In some embodiments, the chemical composition of the aluminum-containing coating, by mass percentage, includes: Si: 7%–12%, Fe: 1%–3%, with the balance being Al and other unavoidable impurities.

[0045] In some embodiments, the chemical composition of the aluminum-containing coating, by mass percentage, includes: Si: 7%–12%, Fe: 1%–3%, with the balance being Al and other unavoidable impurities. When the Si content is too high, the surface roughness of the hot-stamped components obtained from the aluminized steel sheet is too low, making them unsuitable for electrophoretic coating. When the Si content is too low, the aluminum-containing coating on the hot-stamped components obtained from the aluminized steel sheet is more prone to cracking, leading to reduced corrosion resistance. By controlling the Si content to 7%–12%, excellent overall performance of the aluminum-containing coating can be achieved. Simultaneously, if the Fe content is too low, it can easily lead to the dissolution of the steel strip during hot-dip galvanizing, increasing the risk of strip breakage; if the Fe content is too high, it can easily lead to the generation of a large amount of aluminum dross, affecting the surface quality of the aluminized steel sheet.

[0046] In some embodiments, the aluminum-containing coating may be an Al-Fe-Si alloy coating, which may include a variety of alloy phases and / or intermetallic compounds.

[0047] In some embodiments, the chemical composition of the substrate, by mass percentage, includes: C: 0.05%–0.40%, Si: 0.05%–0.3%, Mn: 0.8%–2%, P ≤0.03%, S ≤0.01%, Al ≤0.5%, N: ≤0.01%, B: 0.0005%–0.005%, Cr: 0.10%–0.5%, Ni: 0.001%–0.5%, Mo: 0.001%–0.5%, and one or more of Ti 0.01%–0.10%, Nb 0.01%–0.10%, and V 0.02%–0.15%, with the remainder being Fe and unavoidable impurities.

[0048] In some embodiments, the chemical composition of the substrate, expressed as a percentage by mass, satisfies the following relationships: 1.5% ≤ (Cr + Mn + Ni + Mo) ≤ 2.5% and 0.5 × Mn + Cr + 0.5 × Ni > 0.7; 0.03% ≤ (Ti + Nb + V) ≤ 0.30%.

[0049] Typically, when the tensile strength of the substrate is 500 MPa to 1200 MPa, the mass percentage of carbon in the substrate is 0.05% to 0.12%; when the tensile strength of the substrate is 1200 MPa to 2200 MPa (excluding 1200 MPa), the mass percentage of carbon in the substrate is 0.18% to 0.40%.

[0050] The functions of each chemical component in the substrate are as follows:

[0051] C is the most effective and cheapest solid solution strengthening element, which can effectively guarantee the strength level of hot stamping steel (substrate). At the same time, C is an austenite stabilizing element, which can most effectively stabilize austenite.

[0052] When the tensile strength of the substrate is 500MPa to 1200MPa, the mass percentage of the C element chemical composition of the substrate is 0.05% to 0.12%. At this time, the strength requirement is relatively low, and the strength and toughness of the substrate can be improved by adding trace amounts of alloying elements.

[0053] When the tensile strength of the substrate is 1200 MPa to 2200 MPa (excluding 1200 MPa), the mass percentage of carbon (C) in the substrate is 0.18% to 0.40%. If the mass percentage of C in the substrate exceeds 0.40%, it is not conducive to obtaining toughness and plasticity; if the mass percentage of C in the substrate is less than 0.18%, it is not conducive to forming sufficient strengthening effect to obtain stable high-dislocation martensite and improve the strength of the steel plate.

[0054] Mn is used to increase the austenite region and lower the austenitizing temperature, thereby improving hardenability.

[0055] Cr can significantly increase hardenability and reduce severe oxidation defects on high-temperature surfaces, but it can promote the formation of bainite, so the mass percentage of Cr in the substrate should not be too high.

[0056] Ni effectively improves hardenability and low-temperature toughness. On the one hand, it significantly increases the strength of steel, and on the other hand, it maintains a high level of toughness in the iron (substrate) while keeping the brittleness temperature low. Hardenability is further enhanced when Ni is combined with Cr or Mo. Nickel-molybdenum steel also exhibits a high fatigue limit.

[0057] Mo can refine the grain structure of steel and improve hardenability. However, the addition of Mo increases costs, therefore the mass percentage of Mo in the substrate can be limited to less than or equal to 0.5%.

[0058] In some embodiments, to ensure that the substrate has sufficiently high strength, the mass percentage of alloying elements affecting the substrate strength can be limited to satisfying (Cr+Mn+Ni+Mo)≥1.5%; to balance toughness, the mass percentage of alloying elements affecting the substrate hardenability can be limited to satisfying (Cr+Mn+Ni+Mo)≤2.5%. Meanwhile, to avoid excessive Cr mass percentage leading to excessive carbide formation, the chemical composition of the substrate can be designed primarily with the addition of Mn and Ni to increase their influence factors.

[0059] Phosphorus (P) tends to form micro-segregations during the solidification of molten steel in the substrate. These segregations then agglomerate at grain boundaries during post-austenite heating, significantly increasing the steel's brittleness and thus raising its susceptibility to hydrogen-induced delayed fracture. Therefore, the mass percentage of P should be controlled below 0.01%.

[0060] S is an unavoidable impurity. The MnS inclusions formed and the segregation at grain boundaries deteriorate the toughness of the substrate, thereby reducing the toughness and plasticity of the steel (substrate) and increasing the susceptibility to hydrogen-induced delayed fracture. Therefore, the mass percentage of S can be controlled below 0.01%.

[0061] Nitrogen (N) combines with Al, Ti, Nb, V, etc., to form compounds, thereby refining grains and reducing the susceptibility to hydrogen-induced delayed fracture. However, it can also segregate at grain boundaries, reducing grain boundary strength. Therefore, the mass percentage of N can be controlled below 0.01%.

[0062] Nb, Ti, and V combine with C and N to form precipitates, primarily used to refine austenite grains. This disclosure adds a specific amount of V to the alloy composition, which allows for the precipitation of a certain amount of VC or (V, Ti / Nb)C composite carbides at grain boundaries during the hot stamping process (with a full austenitization heating temperature range of 850℃~950℃). This is because the addition of second-phase particles to the substrate material effectively pins the austenite grains, refining the original austenite grains. If (Ti+Nb+V) > 0.3%, it may lead to coarsening of the precipitates, which is not conducive to obtaining nanoscale dispersed precipitates. Furthermore, the precipitation strengthening effect of (Ti+Nb+V) > 0.3% is not significant and may increase costs. If (Ti+Nb+V) < 0.03%, it is insufficient to form enough precipitates, and it is difficult to obtain precipitation strengthening and grain refinement effects. Additionally, the number of H traps formed by the precipitates is insufficient, resulting in reduced strength and toughness.

[0063] The presence of a small amount of boron ensures that the substrate has sufficient hardenability.

[0064] Figure 1 shows a schematic flowchart of a method for preparing an aluminized steel sheet according to some embodiments of the present disclosure. As shown in Figure 1, based on a general inventive concept, the above-described method for preparing an aluminized steel sheet according to some embodiments of the present disclosure includes: rolling a steel billet to obtain a substrate; immersing the substrate in an aluminum-containing plating solution for aluminum plating treatment to form an aluminum-containing coating; and spraying zinc-containing particles during the solidification process of the aluminum-containing plating solution to form a zinc-containing layer, thereby obtaining the aluminized steel sheet; wherein the zinc-containing layer includes a zinc-containing alloy layer and / or a zinc-containing oxide layer.

[0065] This method is used for the preparation of the above-mentioned aluminized steel sheet. The relevant content of the aluminized steel sheet can be referred to the above embodiments. Since this method adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0066] In some embodiments, the method for preparing aluminized steel sheet includes:

[0067] Step S1. Roll the steel billet to obtain a substrate.

[0068] In step S1 of some embodiments, rolling the billet may include smelting a billet with the required composition for casting, and then hot rolling, pickling and cold rolling the billet to obtain a substrate.

[0069] In some embodiments, the cold-rolled steel billet can be annealed in an annealing furnace with a reducing atmosphere at a temperature of 720°C to 850°C. The reducing atmosphere in the annealing furnace, by volume percentage, includes: H2: 3% to 10%, with the balance being N2; the dew point in the annealing furnace is controlled at -50°C to 10°C.

[0070] In some embodiments, the method for preparing aluminized steel sheet further includes:

[0071] Step S2. Immerse the substrate in an aluminum-containing plating solution for aluminum plating to form an aluminum-containing coating; during the solidification process of the aluminum-containing plating solution, spray zinc-containing particles to form a zinc-containing layer to obtain an aluminum-plated steel sheet, wherein the zinc-containing layer includes a zinc-containing alloy layer and / or a zinc-containing oxide layer.

[0072] In step S2 of some embodiments, zinc-containing particles adhere to the surface of the incompletely solidified aluminum-containing coating through a circulation pipe at high temperature, as shown in Figure 2. This helps reduce the coefficient of friction of the aluminized steel sheet during subsequent hot stamping. In other words, by forming a zinc-containing layer in all or part of the aluminum-containing coating surface, lubrication during hot pressing can be ensured, thereby mitigating the problem of roughening or mold damage that easily occurs in aluminum alloy coated steel during hot stamping in related technologies.

[0073] In step S2 of some embodiments, the substrate is continuously annealed and then immersed in an aluminum-containing plating solution to obtain a steel plate with an aluminum-containing plating layer on the surface composed of aluminum-containing plating solution elements; during the solidification process of the aluminum-containing plating solution, Zn powder or Zn alloy powder as aluminum particles is sprayed onto the high-temperature aluminum-containing plating layer to form a zinc-containing layer attached to the side of the aluminum-containing plating layer away from the substrate, so as to obtain an aluminum-plated steel plate.

[0074] In some embodiments, after step S2, the following operations may also be performed: the aluminized steel sheet is sequentially stretched, smoothed and coiled to obtain a steel coil; when needed, the steel coil can be uncoiled and blanked to obtain a steel plate blank for stamping.

[0075] In some embodiments, the zinc-containing particles include at least one of zinc powder and zinc alloy powder.

[0076] In some embodiments, the zinc content in the zinc-containing particles is ≥50% by mass.

[0077] In some embodiments, the particle size of the zinc-containing particles is 300 mesh to 1200 mesh.

[0078] In some embodiments, the zinc-containing particles result in an area coverage of ≥80% of a zinc-containing layer on one side of the substrate, where the zinc content by mass is greater than 0.5%.

[0079] In some embodiments, the number of zinc-containing particles sprayed on one side of the substrate is 10 particles / cm. 2 ~500 pieces / cm 2 If the amount of zinc-containing particles sprayed is too small, it will not be effective. If the amount of zinc-containing particles sprayed is too large, it will lead to an increase in zinc oxide content, which will affect the surface roughness of the aluminized steel sheet and will be detrimental to the coating performance of the aluminized steel sheet, thus causing defects such as electrophoretic pinholes during electrophoretic coating.

[0080] In some embodiments, the temperature of the aluminum plating solution is 650°C to 680°C.

[0081] In some embodiments, the temperature of the substrate is 550°C to 640°C during the spraying of zinc-containing particles.

[0082] By controlling the temperature of the aluminum plating solution to 650℃~680℃ and the substrate temperature to 550℃~640℃, it is beneficial to ensure that the surface temperature of the aluminum plating layer is 550℃~640℃ during the spraying of zinc particles, thus promoting the adhesion of the zinc particles. If the temperature of the aluminum plating solution and the substrate is too high, the zinc particles are prone to evaporation, affecting the final effect; if the temperature of the aluminum plating solution and the substrate is too low, the zinc particles are prone to diffusion with the aluminum plating layer, making it difficult to form a zinc layer on the side of the aluminum plating layer away from the substrate, thereby reducing the adhesion of the paint film on the aluminized steel sheet.

[0083] Based on a general inventive concept, the components according to some embodiments of this disclosure are made of materials including the aforementioned aluminized steel sheet.

[0084] This component is made based on the above-mentioned aluminized steel sheet. The relevant content of the aluminized steel sheet can be referred to the above embodiments. Since this component adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0085] The components can be automotive safety parts, such as: front / rear door anti-collision beams, bumpers, A / B pillar reinforcement plates, floor center tunnels and other safety components.

[0086] Based on a general inventive concept, a method for preparing a component according to some embodiments of this disclosure includes:

[0087] Aluminized steel sheet is obtained;

[0088] S1. Heat treatment of the aluminized steel sheet; and,

[0089] S2. The heat-treated aluminized steel sheet is stamped to form the component.

[0090] This method is used for the preparation of the aforementioned components. The relevant details of these components can be found in the above embodiments. The relevant details of the aluminized steel sheet in this method can also be found in the above embodiments. Since this method adopts some or all of the technical solutions of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here. During hot pressing, the aluminum-containing coating is highly brittle and prone to cracking, leading to a decrease in the corrosion resistance of the stamped component after coating. In some embodiments of this disclosure, by raising the hot stamping temperature above 650°C, the forming resistance of the aluminized steel sheet can be effectively reduced, thus reducing the cracking risk of the aluminum-containing coating in the aluminized steel sheet. As the holding time during stamping increases, the proportion of iron-aluminum alloy in the aluminum-containing coating increases, leading to a decrease in roughness. Therefore, the upper limit of the holding temperature and holding time for stamping is limited to 960°C / 500s.

[0091] In some embodiments, the heat treatment includes a first heat treatment and a second heat treatment. The temperature of the first heat treatment is 650°C to 900°C, and the time of the first heat treatment is 30s to 150s. The temperature of the second heat treatment is 900°C to 960°C, and the time of the second heat treatment is 200s to 400s.

[0092] In some embodiments, the heating rate of the heat treatment does not exceed 15°C / s.

[0093] In some embodiments, the furnace time for heat treatment is 250s to 500s.

[0094] By limiting the heating rate of heat treatment or the alloying time (furnace time), Fe elements in the substrate can enter the aluminum-containing coating at a relatively low temperature, increasing the melting point of the aluminum-containing coating and reducing its emissivity. However, increasing the heating efficiency at high temperatures, especially if the heating rate is too fast, can easily lead to the evaporation of zinc particles.

[0095] In some embodiments, during the heat treatment step of the manufacturing process of the thermoformed component, the aluminized steel sheet is placed in a heating furnace for heating and holding, including but not limited to a box furnace or a tunnel roller hearth furnace. During the heating process in the heating furnace, the aluminized steel sheet is heated and held in the furnace at 650°C to 900°C for 30s to 150s, with a heating rate not exceeding 15°C / s; then it continues to be held at a furnace temperature of 900°C to 960°C for 200s to 400s, with a total furnace time of 250s to 500s.

[0096] In the above heat treatment process, the atmosphere inside the heating furnace is dry air or nitrogen. By controlling the total furnace heat treatment time to 250s–500s and the maximum heat treatment temperature to 960℃, the surface roughness of the finished aluminized steel sheet can be guaranteed, while ensuring sufficient austenitization of the components. If the temperature is too high, cracks may easily form in the aluminized steel sheet, which will reduce the corrosion resistance of the stamped components after coating. If the heat treatment time is too long, the proportion of iron-aluminum alloy phase on the surface of the aluminized steel sheet may increase, leading to a decrease in the surface roughness of the aluminized steel sheet.

[0097] In some embodiments, the stamping temperature is ≥650°C.

[0098] In some embodiments, the holding pressure during stamping is ≥5MPa.

[0099] In some embodiments, the holding time for stamping is ≥5s.

[0100] In some embodiments, the finishing temperature of stamping is ≤160°C.

[0101] In some embodiments, the heat-treated billet (aluminized steel sheet) is transferred to the mold for stamping within 3s to 15s after exiting the furnace, the stamping temperature is ≥650℃; the stamping pressure is ≥5MPa, the stamping holding time is ≥5s; the stamping end temperature is ≤160℃, that is, the component temperature after mold opening is ≤160℃.

[0102] The component, after stamping, has a yield strength of 350MPa to 1400MPa, a tensile strength of 500MPa to 2200MPa, and an elongation of ≥4%. When used as an automotive structural component, after baking with the body-in-white paint, the component has a yield strength of 400MPa to 1600MPa, a tensile strength of 450MPa to 2100MPa, and an elongation of ≥5%.

[0103] After painting, the component exhibits no cracking or peeling of the paint film, and its cupping and other properties meet the requirements. It demonstrates excellent corrosion resistance, with no blistering or peeling, and the paint film adhesion meets the requirements. It is suitable for automotive safety components, such as front / rear door anti-collision beams, bumpers, A / B pillar reinforcement plates, and floor center tunnels.

[0104] The present disclosure is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the disclosure. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0105] Examples and Comparative Examples

[0106] A component, the preparation process of which is as follows:

[0107] (1) The steel billet required for casting is smelted, and then hot-rolled, pickled, and cold-rolled to obtain the substrate. The chemical composition of the substrates of each embodiment and comparative example is shown in Table 1 below:

[0108] Table 1 Chemical composition of the substrates of each embodiment and comparative example

[0109] In the table, "-" indicates that the substance is not present.

[0110] In the table, the balance of the substrate's chemical composition is Fe, and unavoidable impurities are not shown.

[0111] (2) After continuous annealing, the substrate is immersed in an aluminum-containing plating solution to obtain a steel plate with an aluminum-containing plating layer on its surface. During the solidification process of the aluminum-containing plating solution, zinc-containing particles are sprayed onto the aluminum-containing plating layer of the high-temperature substrate. The chemical composition and zinc content parameters of the aluminum-containing plating solutions in each embodiment and comparative example are shown in Table 2 below:

[0112] Table 2. Chemical composition and zinc content control parameters of aluminum-containing plating solutions in each embodiment and comparative example.

[0113] In the table, "-" indicates that the operation is not performed.

[0114] (3) The aluminized steel sheet is stretched, smoothed and coiled in sequence to obtain a steel coil; the steel coil is uncoiled and blanked to obtain a steel plate blank for stamping.

[0115] (4) The steel plate billet is heat-treated, and the heat-treated steel plate billet is quickly transferred to a mold for cooling and stamping to obtain a stamped component. The parameters for heat treatment and stamping of each embodiment and comparative example are shown in Table 3 below:

[0116] Table 3. Parameter control for heat treatment and stamping in each embodiment and comparative example.

[0117] In the table, "-" indicates that the operation is not performed.

[0118] The performance of the components prepared in each embodiment and comparative example was tested, and the results are shown in Table 4 below.

[0119] Table 4. Performance test results of the components prepared in each embodiment and comparative example.

[0120] In the table, "-" indicates that the operation is not performed or the structural layer is not included.

[0121] As shown in Table 4, the high-temperature friction coefficient of the components prepared in Examples 1-4 is lower than that of the components provided in Comparative Examples 1-2 without zinc powder coating, and the weight of the phosphate film is significantly increased. After 1000h of neutral salt spray test, the maximum erosion width at the cross-shaped part of the electrophoretic coating film in Comparative Example 2 is lower, but the coating thickness is thicker, which will seriously affect the welding performance and easily lead to welding spatter.

[0122] As shown in Table 4, after the aluminized steel sheet undergoes the first heat treatment, the second heat treatment, and the stamping process, a certain degree of interdiffusion occurs between the aluminum-containing coating and the substrate, forming a coating alloy layer mainly composed of aluminum and iron. In this embodiment, the thickness of the coating alloy layer can be 6 μm to 8 μm. The formation of the coating alloy layer reduces the substrate thickness and increases the total coating thickness (the sum of the aluminum-containing coating and the coating alloy layer). In this embodiment, the total coating thickness can be 12 μm to 28 μm. A certain degree of interdiffusion also occurs between the zinc-containing layer and the aluminum-containing coating, forming a diffusion bonding layer. The diffusion of the zinc-containing layer, which includes a zinc-containing alloy layer and / or a zinc-containing oxide layer, into the aluminum-containing coating increases the thickness of the zinc-containing layer. In this embodiment, the thickness of the zinc-containing layer can be 12 μm to 24.5 μm.

[0123] Detailed description of the attached diagram:

[0124] Figures 3 to 6 show the SEM images and energy dispersive spectroscopy (EDS) images of the aluminized steel sheet before and after stamping in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure. As can be seen from the figures, before stamping, zinc powder particles are mainly attached to the coating surface and diffuse to a certain extent, which can improve the bonding force.

[0125] Figure 7 shows the GDS diagrams of the aluminized steel sheet before and after stamping in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure. As can be seen from the figure, before stamping, the thickness of the zinc-containing alloy layer and / or zinc-containing oxide layer on the aluminum-containing coating surface of the aluminized steel sheet is about 16 μm. After stamping, the thickness of the zinc-containing alloy layer and / or zinc-containing oxide layer on the aluminum-containing coating surface of the component obtained from the aluminized steel sheet is about 22 μm.

[0126] Figures 8 and 9 show the morphology and energy dispersive spectroscopy (EDS) of the phosphate film after heat treatment of the aluminized steel sheet in the preparation method of the aluminized steel sheet according to Embodiment 1 of this disclosure. Figures 10 and 11 show the surface P signal diagrams of the aluminized steel sheet after phosphate treatment in the preparation methods of the aluminized steel sheet according to Embodiment 1 and Comparative Example 1 of this disclosure, respectively. As can be seen from the figures, the components prepared in the embodiments of this disclosure can form a good phosphate film, which is beneficial to the adhesion of the paint film.

[0127] The aluminized steel sheet according to some embodiments of this disclosure has the following advantages compared with related technologies:

[0128] According to some embodiments of the present disclosure, the aluminized steel sheet, by providing a zinc-containing alloy layer and / or a zinc-containing oxide layer on the aluminum-containing coating, helps to reduce the coefficient of friction during the stamping process, thereby improving to some extent the problem of roughening or mold damage that easily occurs in the stamping process of aluminized steel sheets in related technologies; at the same time, it can also improve the phosphating performance, which is beneficial to the corrosion resistance and adhesion of the subsequent electrophoretic coating film, and helps to improve the adhesion of the coating film.

[0129] Although this disclosure uses a spraying method to prepare the zinc-containing surface layer, it is not limited to the spraying method.

[0130] Various embodiments of this disclosure may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this disclosure; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0131] In this disclosure, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the orientation shown in the accompanying drawings. Furthermore, in the description of this disclosure, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships may exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b or c" or "at least one of a, b and c" can both mean: a, b, c, a~b (i.e. a and b), a~c, b~c, or a~b~c, where a, b, and c can be a single or multiple.

[0132] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An aluminized steel sheet, comprising a substrate, an aluminum-containing coating, and a zinc-containing layer, wherein the aluminum-containing coating is attached to the substrate, and the zinc-containing layer is attached to the side of the aluminum-containing coating away from the substrate, wherein the zinc-containing layer comprises a zinc-containing alloy layer and / or a zinc-containing oxide layer.

2. The aluminum-plated steel sheet according to claim 1, wherein A diffusion bonding layer exists between the zinc-containing layer and the aluminum-containing coating.

3. The aluminum-plated steel sheet according to claim 1, wherein The zinc-containing layer on one side of the aluminized steel sheet has a zinc content greater than 0.5% and an area coverage rate of ≥80%; and / or, The depth of the zinc-containing layer ranges from 0.4 μm to 29 μm; and / or, The zinc content of the zinc-containing layer is 0.1 g / m 2 ~ 8 g / m 2 .

4. The aluminum-plated steel sheet according to claim 1, wherein The aluminum-containing coating includes an alloy coating containing an Al-Fe-Si system; and / or, The aluminum-containing coating comprises various alloy phases and intermetallic compound phases; and / or, The thickness of the aluminum-containing coating is 4 μm to 50 μm; and / or, The single-sided loading of the aluminum-containing plating layer is 10 g / m 2 ~ 100 g / m 2 ; And / or, The chemical composition of the aluminum-containing coating, by mass percentage, includes: Si: 7%–12%, Fe: 1%–3%, with the balance being Al and other unavoidable impurities.

5. The aluminized steel sheet according to claim 1, wherein The chemical composition of the substrate, by mass percentage, includes: C: 0.05%–0.4%, Si: 0.05%–0.3%, Mn: 0.8%–2%, P ≤ 0.03%, S ≤ 0.01%, Al ≤ 0.5%, N: ≤ 0.01%, B: 0.0005%–0.005%, Cr: 0.10%–0.5%, Ni: 0.001%–0.5%, Mo: 0.001%–0.5%, and one or more of Ti 0.01%–0.10%, Nb 0.01%–0.10%, and V 0.02%–0.15%, with the remainder being Fe and other unavoidable impurities; and / or, The chemical composition of the substrate, expressed as a percentage by mass, satisfies the following relationships: 1.5% ≤ (Cr + Mn + Ni + Mo) ≤ 2.5% and 0.5 × Mn + Cr + 0.5 × Ni > 0.7%, 0.03% ≤ (Ti + Nb + V) ≤ 0.30%.

6. A method for preparing an aluminized steel sheet as described in any one of claims 1 to 5, comprising: The steel billet is rolled to obtain a substrate; and, The substrate is immersed in an aluminum-containing plating solution for aluminum plating treatment to form an aluminum-containing coating. During the solidification process of the aluminum-containing plating solution, zinc-containing particles are sprayed to form a zinc-containing layer, thereby obtaining the aluminum-plated steel sheet; The zinc-containing layer includes a zinc-containing alloy layer and / or a zinc-containing oxide layer.

7. The method of producing an aluminum-plated steel sheet according to claim 6, wherein The zinc-containing particles include at least one of zinc powder and zinc alloy powder, and / or, The zinc-containing particles contain ≥50% zinc by mass; and / or, The zinc-containing particles have a particle size of 300 mesh to 1200 mesh; and / or, The zinc-containing particles ensure that the area coverage of the zinc-containing layer on one side of the substrate has a zinc content greater than 0.5% by mass ≥ 80%; and / or, The temperature of the aluminum-containing plating solution is 650℃~680℃; and / or, During the process of spraying the zinc-containing particles, the temperature of the substrate is 550°C to 640°C.

8. A component, the material of which comprises the aluminized steel sheet according to any one of claims 1 to 5.

9. A method for preparing a component, comprising: Aluminized steel sheet as described in any one of claims 1 to 5 is obtained; The aluminized steel sheet is heat-treated; as well as, The heat-treated aluminized steel sheet is stamped to form the component.

10. The method of making a structure according to claim 9, wherein, The heat treatment includes a first heat treatment and a second heat treatment. The temperature of the first heat treatment is 650℃~900℃, and the time of the first heat treatment is 30s~150s. The temperature of the second heat treatment is 900℃~960℃, and the time of the second heat treatment is 200s~400s. And / or, The heating rate of the heat treatment shall not exceed 15°C / s; and / or, The furnace time for the heat treatment is 250s to 500s; and / or, The stamping temperature is ≥650℃; and / or, The holding pressure of the stamping process is ≥5MPa; and / or, The holding time for the stamping process is ≥5s; and / or, The finishing temperature of the stamping process is ≤160℃.

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