Aluminum-based plated hot-formed steel sheet having high heating efficiency and paint adhesion, and manufacturing method and application thereof

Abstract

The application provides an aluminum-plated hot-formed steel plate with high heating efficiency and paint adhesion, a manufacturing method and application, and belongs to the field of aluminum-plated hot-formed steel plate production.Compared with the prior art, the application improves the heat absorption efficiency of the aluminum-plated hot-formed steel by applying a lithium manganate surface treatment layer on the surface of the aluminum plating layer, reduces the heating time of hot forming, and significantly improves the coating performance after hot forming, and has excellent paint adhesion and corrosion resistance after painting.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aluminum-based plated hot forming steel plate production, and particularly relates to an aluminum-based plated hot forming steel plate with high heating efficiency and paint adhesion, a manufacturing method and application thereof. BACKGROUND

[0002] Due to the requirements of lightweight and corrosion resistance, high-strength coated hot forming steels are widely used in automobile parts. Among the coated hot forming steels, aluminum-silicon plated hot forming steel plates are widely used. In the production of hot forming steel plates, it is desirable to shorten the heating time in the furnace as much as possible for the consideration of production efficiency and energy saving and emission reduction. However, the aluminum-silicon plating layer has high reflectivity during heating, which reduces the heating efficiency.

[0003] In addition, the body parts need to be phosphated to form a phosphating film to ensure the adhesion between the paint and the substrate. However, the aluminum-silicon plated hot forming steel is difficult to form a film on the surface after hot forming. The current practice is to heat sufficiently during heating to form a surface rough alloyed phase structure of the plating layer, so as to ensure the adhesion and corrosion resistance of the paint. Therefore, in order to ensure the adhesion and corrosion resistance of the product, sufficient heating, high heating temperature and time are required, but this inevitably leads to low heating efficiency.

[0004] In the prior art for improving the coating performance of aluminum-silicon plating layer, a patent with publication number CN107250414 A published on October 13, 2017 discloses a method for producing phosphate-able parts from a plate coated with an aluminum-based coating and a zinc coating, which discloses a steel plate coated with an aluminum-based coating and further comprising a second zinc coating, which has the effect of improving phosphate surface treatment, but the heating time of the examples disclosed is more than 5 min at 900℃, which does not solve the problem of low heating efficiency.

[0005] In summary, due to the contradictory problems of sufficient heating to ensure phosphating performance, improve adhesion and improve heating efficiency, there is currently a lack of technical solutions to simultaneously improve the heating efficiency and paint adhesion of aluminum-silicon plated hot forming steel. SUMMARY

[0006] The present application aims to provide an aluminum-based plated hot forming steel plate with high heating efficiency and paint adhesion, and a manufacturing method, which improves the heating efficiency by forming spinel-type lithium manganate in hot forming by applying a surface treatment layer on the surface of the aluminum plating layer, and reduces the hot forming heating time; at the same time, the present application significantly improves the coating performance after hot forming, and has excellent post-paint adhesion and corrosion resistance.

[0007] The present application also aims to provide an application of an aluminum-based plated hot forming steel plate with high heating efficiency and paint adhesion, which is used in the manufacture of automobile parts.

[0008] The technical scheme of the present application is as follows:

[0009] An aluminum plated hot forming steel sheet with high heating efficiency and paint adhesion, comprising a steel substrate, an aluminum alloy plating layer and a surface treatment layer;

[0010] The surface treatment layer contains Li, Mn and O elements, and the molar ratio of Li and Mn is 0.45-0.55:1. This element ratio can form spinel lithium manganate in hot forming to improve heating efficiency. When Li:Mn < 0.45, a large amount of Mn will appear in the form of yellow rust-like Mn3O4 after hot pressing, which cannot be accepted by the automobile industry. When Li:Mn > 0.55, there will be more Li that cannot play a role, increasing the cost.

[0011] Preferably, the composition of the surface treatment layer includes lithium manganate;

[0012] One or more cation doping elements can be doped in the surface treatment layer to enhance the high-temperature stability of lithium manganate, including Al, Mg, Fe, Co, Cr and other metal elements, preferably without special doping of these elements.

[0013] The surface treatment layer has a weight of 0.01-0.50 g / m 2 of Li content, lower than 0.01 g / m 2 , and higher than 0.50 g / m 2 , which cannot continue to improve the heating efficiency, and as a cost, lower than 0.50 g / m 2 .

[0014] The steel substrate of the aluminum plated hot forming steel sheet with high heating efficiency and paint adhesion has an aluminum alloy plating layer and a surface treatment layer on at least one surface;

[0015] The composition of the aluminum alloy plating layer includes 8-12% Si, up to 2% Fe, the rest being aluminum and unavoidable impurities;

[0016] The aluminum alloy plating layer has a weight of 20-80 g / m 2 per single side;

[0017] The steel substrate can be selected from substrates capable of producing an aluminum plated hot forming steel plate, for example, the steel substrate can be a 22MnB5 steel plate including the following mass percentage components: 0.20%≤C≤0.25%; 0.15%≤Si≤0.35%; 1.10%≤Mn≤1.40%; 0%≤Cr≤0.30%; 0%≤Mo≤0.35%; 0%≤P≤0.025%; 0%≤S≤0.005%; 0.020%≤Ti≤0.060%; 0.020%≤Al≤0.060%; 0.002%≤B≤0.004%, and the balance being iron and unavoidable impurities from steel manufacturing.

[0018] Further, the surface treatment layer is an anti-rust oil layer;

[0019] The aluminum plated hot forming steel plate with high heating efficiency and paint adhesion has an aluminum alloy plating layer and a surface treatment layer on the steel substrate.

[0020] Or, the aluminum plated hot forming steel plate with high heating efficiency and paint adhesion has an aluminum alloy plating layer, a surface treatment layer, and an anti-rust oil layer on the steel substrate.

[0021] The application provides a manufacturing method of an aluminum plated hot forming steel plate with high heating efficiency and paint adhesion, specifically including: applying a coating containing a manganese source and a lithium source on an aluminum alloy plating layer steel plate and heating and drying.

[0022] Further, the method has a degreasing step before the application, to wash away surface contaminants.

[0023] Further, the method has a water washing step after the degreasing, to avoid the degreasing solution remaining on the surface.

[0024] Further, the method has a drying step after the water washing, and then the application.

[0025] The coating containing the manganese source and the lithium source is obtained by dispersing the manganese source and the lithium source with a solvent;

[0026] The solvent of the coating containing the manganese source and the lithium source is water, ethanol, acetone, butyl ether, or N-methyl-2-pyrrolidone;

[0027] In the coating containing the manganese source and the lithium source, the molar ratio of the lithium source to the manganese source is 0.45-0.55:1;

[0028] The total mass concentration of the manganese source and the lithium source in the coating is 40-50 g / L;

[0029] The manganese source and the lithium source can be from the same raw material or different raw materials; if from the same raw material, the manganese source and the lithium source are both lithium manganate; when from different raw materials, the manganese source is selected from manganese acetate, and the lithium source is selected from lithium carbonate or lithium acetate;

[0030] Further, the coating containing the manganese source and the lithium source also contains a binder to enhance the adhesion of the coating to the plated layer and prevent the coating from falling off before hot pressing. The type of the binder is not particularly limited, and examples of the binder that can be used as a conventional embodiment include polyvinylpyrrolidone, polyacrylic acid resin, polyurethane, hydroxypropyl methylcellulose, silane, and polyvinylidene fluoride.

[0031] If the binder is contained, the concentration of the binder in the coating is 5-20 g / L;

[0032] The aluminum alloy plated steel sheet is obtained by hot dipping, and the specific method is as follows: the steel substrate is hot-dipped in a hot-rolled or annealed state to obtain an aluminum alloy plated steel sheet, for example, by hot rolling→ pickling→ hot dipping→ flattening to obtain an aluminum alloy plated steel sheet with a hot base; or, for another example, by hot rolling→ pickling→ cold rolling→ cleaning→ annealing→ hot dipping→ flattening to obtain an aluminum alloy plated steel sheet. The aluminum alloy plated layer of the obtained aluminum alloy plated steel sheet contains the following components in mass percent: 8-12% of Si, at most 2% of Fe, and the balance of aluminum and unavoidable impurities. The aluminum alloy plated steel sheet can be prepared according to a conventional method.

[0033] In the above-mentioned aluminum alloy plated layer components, Si can form an Fe-Al-Si inhibition layer on the surface of the steel sheet, which can effectively hinder the formation of the brittle phase Fe2Al5 and improve the adhesion of the plated layer. When the content of Si is less than 8%, the Fe-Al alloy layer becomes thick, and the adhesion of the plated layer decreases. When the content of Si is greater than 12.0%, the surface quality of the plated layer is affected. According to the above situation, the content of Si in the plated layer is controlled to be 8.0-12.0%.

[0034] In the method for manufacturing an aluminum plated hot forming steel sheet with high heating efficiency and paint adhesion, the heating and drying is performed at a temperature of 80-300°C for 5-120 s, and after the heating and drying, lithium manganate or a precursor thereof is formed, and the precursor can further form lithium manganate under heat during hot stamping forming.

[0035] The application provides an aluminum plated hot forming steel sheet with high heating efficiency and paint adhesion.

[0036] The specific application method is as follows: after the aluminum plated hot forming steel sheet with high heating efficiency and paint adhesion is made into a blank, the blank is heated and kept warm, and then hot stamping is performed.

[0037] The plated steel sheet with the surface treatment layer of the present application can significantly improve the heating efficiency. As a common hot stamping process, the steel sheet is cut to obtain a blank, the blank is heated to 840-1100℃, and then the blank is transferred to a hot stamping tool for hot stamping.

[0038] The heating has a temperature rising rate of ≥5℃ / s.

[0039] When the thickness of the blank is ≥1.4mm, the total heating and holding time is 3-5min; when the thickness of the blank is <1.4mm, the total heating and holding time is 1-3min, preferably ≤2.5min. Due to the presence of the surface treatment layer, the heat absorption efficiency of the sheet is improved, and the time required for heating to the austenitizing temperature is shorter, and the heating time of this heating process is shortened by more than 1min compared with the conventional hot forming process.

[0040] Further, the blank after heating and holding is transferred to a hot stamping tool, and the blank is hot stamped at a temperature of 500-700℃.

[0041] Further, after hot stamping, the obtained part is cooled in the tool itself or after being transferred to a specific cooling tool.

[0042] The aluminum plated hot forming steel sheet produced by the present application has excellent coating performance, and the hot forming process does not need to be specially controlled. The lithium manganate in the present application is a blackish gray material, has good heat absorption effect, and can improve the heating efficiency; and the surface lithium manganate can be dissolved in the coating process, in a phosphate environment, the manganate ions can react with phosphoric acid to form a phosphating film, improving the riveting effect with paint, so that the paint adhesion after painting is excellent, and the corrosion resistance is good. Compared with the prior art, by applying a surface treatment layer on the surface of the aluminum plating layer, the heat absorption efficiency of the aluminum plated hot forming steel is improved, and the heating time of hot forming is reduced. At the same time, the coating performance after hot forming is significantly improved, and the corrosion resistance after painting is excellent. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 Structure change schematic diagram of the aluminum plated hot forming steel sheet with high heating efficiency and paint adhesion. DETAILED DESCRIPTION

[0044] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0045] The steel substrate used in the following Examples 1 to 5 and Comparative Examples 1 to 5 includes the following mass percentage components: C 0.2252%, Mn 1.1735%, P 0.0126%, S 0.0009%, Si 0.2534%, Cr 0.180%, Al 0.0371%, Ti 0.0382%, B 0.0028%, Mo 0.0017%, and the balance of iron and unavoidable impurities from steel manufacturing.

[0046] The steel sheets of the above examples and comparative examples are hot-dip plated to obtain an aluminum alloy plated steel sheet in a hot-rolled or annealed state, for example, a hot base aluminum alloy plated steel sheet is obtained by hot rolling→ pickling→ hot-dip plating→ flattening, and further, an aluminum alloy plated steel sheet is obtained by hot rolling→ pickling→ cold rolling→ cleaning→ annealing→ hot-dip plating→ flattening. It can be prepared according to a conventional method. In the prepared aluminum alloy plated steel, the aluminum alloy plating layer contains 8.0-12.0% by mass of Si, 2% by mass of Fe at most, and the balance of aluminum and unavoidable impurities.

[0047] The following is a detailed description of the plating layer obtaining method of each example and comparative example.

[0048] Example 1

[0049] A method for manufacturing an aluminum-based plated hot-formed steel sheet having high heating efficiency and paint adhesion, comprising the following steps:

[0050] 1) First, an aluminum alloy plated steel sheet is prepared using the above-mentioned steel substrate, and the aluminum alloy plated steel sheet is obtained by hot rolling→ pickling→ cold rolling→ cleaning→ annealing→ hot-dip plating→ flattening. After the above-mentioned steps are completed, the aluminum alloy plating layer contains 8.0% by mass of Si, 2.0% by mass of Fe, and the balance of aluminum and unavoidable impurities. The thickness of the sheet is 1.2 mm, and the plating layer is coated on both sides with equal thickness, and the weight of the plating layer on each single side is 75 g / m 2 ;

[0051] 2) Then, a surface layer coating containing a manganese source and a lithium source is prepared, and the coating includes the following mass parts of raw materials:

[0052] Lithium manganate: 40 parts

[0053] Solvent N-methyl-2-pyrrolidone: 50 parts

[0054] Polyvinylpyrrolidone (K90): 10 parts.

[0055] The above-mentioned mass parts of raw materials are mixed uniformly to obtain a coating containing a manganese source and a lithium source, and the coating is coated on the surface of the aluminum alloy plated steel sheet, heated and dried, heated at 150°C for drying, and the drying time is 80s. The specific coating thickness is controlled according to the surface treatment layer Li content in Table 1.

[0056] 3) Apply rust preventive oil on the surface treatment layer, apply 1.5 g / m2 of rust preventive oil of type Ferrocoat N 6130 of Quik. 2 The purpose of applying the rust preventive oil is to temporarily prevent rust and to prevent the plated layer from being scratched when the material is dropped, and since it is decomposed when hot forming, the amount of application does not affect the effect of the present invention.

[0057] Example 2

[0058] A method of manufacturing an aluminum plated hot forming steel sheet having high heating efficiency and paint adhesion, comprising the steps of:

[0059] 1) First, prepare an aluminum alloy plated steel sheet using a steel substrate of the above composition, obtained by hot rolling -> pickling -> hot dipping -> planishing to obtain an aluminum alloy plated steel sheet. After the above steps, the aluminum alloy plated layer contains 9.0% by mass of Si, 1.0% by mass of Fe, and the remainder is aluminum and unavoidable impurities. The sheet thickness is 1.2 mm, and the plated layer is coated to be double-sided and equal thickness, and the plated layer weight per single side is 60 g / m2. 2 .

[0060] Step 2) and Step 3) are the same as in Example 1.

[0061] Example 3

[0062] A method of manufacturing an aluminum plated hot forming steel sheet having high heating efficiency and paint adhesion, comprising the steps of:

[0063] First, prepare an aluminum alloy plated steel sheet using a steel substrate of the above composition, obtained by hot rolling -> pickling -> cold rolling -> cleaning -> annealing -> hot dipping -> planishing to obtain an aluminum alloy plated steel sheet. After the above steps, the aluminum alloy plated layer contains 10.0% by mass of Si, 1.5% by mass of Fe, and the remainder is aluminum and unavoidable impurities. The sheet thickness is 1.4 mm, and the plated layer is coated to be double-sided and equal thickness, and the plated layer weight per single side is 60 g / m2. 2 .

[0064] 2) Then, prepare a surface layer coating containing a manganese source and a lithium source on the surface, and the coating includes the following components:

[0065] Lithium carbonate: 1 mol / L

[0066] Manganese acetate: 2 mol / L

[0067] Hydroxypropyl methylcellulose (20 million viscosity): 20 g / L

[0068] The solvent is water.

[0069] The above ingredients are mixed to obtain a coating containing manganese and lithium sources, which is coated on the surface of the aluminum alloy plated steel sheet, dried by heating, dried at 150°C for 80 seconds, and the coating thickness is controlled according to Table 1.

[0070] 3) Apply rust-proof oil on the surface treatment layer, using Quik Ferrocoat N 6130 type rust-proof oil 1.5 g / m 2 .

[0071] Example 4

[0072] A method for manufacturing an aluminum plated hot-formed steel sheet having high heating efficiency and paint adhesion, comprising the steps of:

[0073] 1) First, an aluminum alloy plated steel sheet is prepared using a steel substrate having the above composition, obtained by hot rolling → pickling → cold rolling → cleaning → annealing → hot dipping → smoothing. After the above steps, the aluminum alloy plating layer contains 12% by mass of Si, 2.0% by mass of Fe, and the remainder is aluminum and unavoidable impurities. The sheet thickness is 1.6 mm, and the plating layer is coated on both sides at the same thickness, with a plating weight of 75 g / m 2 .

[0074] Steps 2) and 3) are the same as in Example 3.

[0075] Example 5

[0076] A method for manufacturing an aluminum plated hot-formed steel sheet having high heating efficiency and paint adhesion, comprising the steps of:

[0077] 1) First, an aluminum alloy plated steel sheet is prepared using a steel substrate having the above composition, obtained by hot rolling → pickling → cold rolling → cleaning → annealing → hot dipping → smoothing. After the above steps, the aluminum alloy plating layer contains 10% by mass of Si, 1.5% by mass of Fe, and the remainder is aluminum and unavoidable impurities. The sheet thickness is 2.0 mm, and the plating layer is coated on both sides at the same thickness, with a plating weight of 75 g / m 2 .

[0078] 2) Then, a surface layer coating containing manganese and lithium sources on the surface is prepared, and the coating includes the following components:

[0079] Lithium carbonate: 1 mol / L

[0080] Manganese acetate: 2.22 mol / L

[0081] Hydroxypropyl methylcellulose (20 million viscosity): 20 g / L

[0082] The solvent is water.

[0083] The above raw materials are mixed in the quality parts to obtain a coating containing manganese source and lithium source, the coating is coated on the surface of the aluminum alloy plated steel plate, and is heated and dried, and is dried at a heating temperature of 150°C for 90s, and the specific coating thickness is controlled according to Table 1, and the surface treatment layer Li content.

[0084] 3) The same as step 3) of Example 3.

[0085] Comparative Example 1

[0086] A manufacturing method of an aluminum plated hot forming steel plate, comprising the following steps:

[0087] 1) Prepared according to the same method as step 1) of Example 1;

[0088] 2) No surface layer coating is prepared, and no surface layer coating is performed;

[0089] 3) According to step 3) of Example 1, except that the rust-proof oil is coated on the aluminum alloy plating layer.

[0090] Comparative Example 2

[0091] A manufacturing method of an aluminum plated hot forming steel plate, comprising the following steps:

[0092] 1) Prepared according to the same method as step 1) of Example 2;

[0093] 2) Then prepare the coating, which comprises the following components:

[0094] Lithium carbonate: 1 mol / L

[0095] Manganese acetate: 2.5 mol / L

[0096] Hydroxypropyl methylcellulose (20 million viscosity): 20 g / L

[0097] The solvent is water.

[0098] The above raw materials are mixed in the quality parts to obtain a coating containing manganese source and lithium source, the coating is coated on the surface of the aluminum alloy plated steel plate, and is heated and dried, and is dried at a heating temperature of 150°C;

[0099] 3) According to step 3) of Example 2.

[0100] Comparative Example 3

[0101] A manufacturing method of an aluminum plated hot forming steel plate, comprising the following steps:

[0102] 1) Prepared according to the same method as step 1) of Example 3;

[0103] 2) Then prepare the coating, which comprises the following components:

[0104] Manganese acetate: 2.0 mol / L

[0105] Hydroxypropyl methyl cellulose (200,000 viscosity): 20 g / L

[0106] The solvent is water.

[0107] The above mass parts of raw materials are mixed to obtain a coating containing a manganese source and a lithium source, the coating is coated on the surface of an aluminum alloy plated steel sheet, and is heated and dried at 150°C.

[0108] 3) The same as step 3) of Example 3.

[0109] Comparative Example 4

[0110] A manufacturing method of an aluminum plated hot-formed steel sheet, comprising the following steps:

[0111] 1) The same as step 1) of Example 4.

[0112] 2) Then prepare a coating, which comprises the following components:

[0113] Lithium carbonate: 1 mol / L

[0114] Hydroxypropyl methyl cellulose (200,000 viscosity): 20 g / L

[0115] The solvent is water.

[0116] The above mass parts of raw materials are mixed to obtain a coating containing a manganese source and a lithium source, the coating is coated on the surface of an aluminum alloy plated steel sheet, and is heated and dried at 150°C.

[0117] 3) The same as step 3) of Example 4.

[0118] Comparative Example 5

[0119] A manufacturing method of an aluminum plated hot-formed steel sheet, comprising the following steps:

[0120] 1) The same as step 1) of Example 5.

[0121] 2) The same as step 2) of Example 5, and the Li content is controlled to be 5 mg / m 2 ;

[0122] 3) The same as step 3) of Example 5, except that the rust-proof oil is coated on the aluminum alloy plating layer.

[0123] The steel sheets of each example and comparative example are evaluated for performance according to the following method:

[0124] Measurement of time required from 20°C to 900°C and heating rate: The cut plate was placed in a 900°C box furnace, and the time required to heat to 900°C was measured using a thermocouple, and the heating rate was calculated.

[0125] Total heating time: The cut plate was placed in a 900°C box furnace, and the total heating time was calculated from the time required to heat to 900°C, using 1 min as a starting point, and then extending by 30 s each time. Then, the 10 mm x 10 mm x plate thickness sample cut from the experimental steel after quenching in the flat plate mold was ground, mechanically polished, and picric acid etched, and the original austenite grain size was observed and measured under an optical microscope, and the martensite structure was observed. The total heating time was the heating time for complete martensite formation.

[0126] The test plate for evaluating the following properties was heated at 930°C for 1.5-8.0 min, and then cooled in a flat plate mold, and the specific heating time is shown in Table 1.

[0127] Phosphating pretreatment performance evaluation: Shanghai Parka Seiko Co., Ltd. FC-L5000A (40 g / L) / FC-E2021SB (16 g / L) two-component automotive degreaser was used, the degreasing solution temperature was 50°C, the steel plate was immersed in the degreasing solution for 2 minutes, then taken out and rinsed with deionized water. After the above degreasing was completed, phosphating treatment was carried out, the sample was immersed in 2 g / L PL-X surface conditioner for 30 s, taken out, and placed in PB-L3035SM type phosphating treatment agent (Shanghai Parka Seiko Co., Ltd.) for phosphating treatment, the phosphating temperature was 35°C, the free acidity FA was 0.9 pt, the total acid TA was 20.0 pt, the accelerator concentration AC was 3.0 pt, and the time was 2 min. After the pretreatment was completed, it was washed and dried. The coverage of the phosphating film was observed using a scanning electron microscope.

[0128] Evaluation method of corrosion resistance after painting: After the pretreatment was completed, electrophoresis was carried out, and an optimized process was used to make the dry film thickness of the electrophoresis 20±2 μm. The electrophoretic paint type was Hunan Xiangjiang Guanxi Coatings HT8000C. After the electrophoresis was completed, a scratch corrosion test was carried out, a scratch knife was used to scratch the paint, then it was placed in a corrosion environment for 26 days, taken out, the floating rust was removed, and the width of the paint peeling in the scratch area was used as an evaluation index. The cyclic corrosion environment test method included 8 h of normal temperature maintenance (25±3°C), 4 times of spraying of salt solution each for 3 min during the period, the salt solution composition was: 0.9 wt% NaCl, 0.1 wt% CaCl2, and 0.0750.9 wt% NaHCO3), 8 hours of humid heat (49±2°C, 100% RH), 8 h of drying (60±2°C, <30% RH), a total of 26 cycles.

[0129] The surface treatment method and evaluation results of each example and comparative example are shown in Table 1.

[0130]

[0131] As Figure 1 , for the structure of aluminum-based plated hot forming steel plate with high heating efficiency and paint adhesion, the steel base is plated with aluminum alloy, and a lithium manganate coating is coated on the aluminum alloy plating, or a precursor coating capable of forming lithium manganate (i.e., a coating containing a manganese source and a lithium source) can also be used. After hot press forming, a lithium manganate surface treatment layer is formed.

[0132] Evaluation results:

[0133] Compared with Comparative Example 1 without surface treatment, Example 1 significantly shortens the temperature rising time from 20 to 900℃, and the heating rate can be increased by more than 40%. The total heating time is shortened by 1 min. Moreover, compared with Comparative Example 1, the pretreatment performance of Example 1 before coating is significantly improved, the phosphating film coverage is significantly improved, and the corrosion resistance after electrophoretic coating is excellent.

[0134] The Li / Mn ratio of Comparative Example 2 is lower than 0.45, although the heating efficiency and the effect of improving the phosphating film are improved, the effect is not as good as Example 2, and the yellow appearance is similar to rust, which is not acceptable.

[0135] Comparative Example 3 uses a single Mn salt for coating, and compared with Example 3, the heating rate is significantly decreased, the phosphating film coverage is slightly decreased, and a yellow Mn3O4 is formed, which is similar to the appearance of rust, and is not acceptable.

[0136] Comparative Example 4 uses a single Li salt for coating, and compared with Example 4, the heating rate, phosphating film coverage, and corrosion resistance after coating are significantly decreased.

[0137] The Li adhesion amount of Comparative Example 5 is 5mg / m 2 Compared with Example 5, the heating rate, phosphating film coverage, and corrosion resistance after coating are all significantly decreased.

[0138] The above description of the embodiments is to facilitate those of ordinary skill in the art to understand and use the invention. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without having to go through creative labor. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art without departing from the scope of the invention should be within the scope of protection of the invention.

Claims

1. An aluminum-coated hot-formed steel sheet with high heating efficiency and paint adhesion, characterized in that, The aluminum-coated hot-formed steel sheet with high heating efficiency and paint adhesion includes a steel substrate, an aluminum alloy coating, and a surface treatment layer. The surface treatment layer contains Li, Mn, and O elements, with a Li to Mn molar ratio of 0.45-0.55:1; spinel-type lithium manganese oxide is formed during thermoforming; the surface treatment layer has a Li content of 0.01-0.50 g / m 2 The weight.

2. The aluminum-coated hot-formed steel sheet with high heating efficiency and paint adhesion according to claim 1, characterized in that, The surface treatment layer comprises lithium manganese oxide.

3. The aluminum-coated hot-formed steel sheet with high heating efficiency and paint adhesion according to claim 1 or 2, characterized in that, The composition of the aluminum alloy coating includes: 8-12% Si, up to 2% Fe, and the remainder being aluminum and unavoidable impurities.

4. The aluminum-coated hot-formed steel sheet with high heating efficiency and paint adhesion according to claim 1 or 2, characterized in that, The aluminum-coated hot-formed steel sheet with high heating efficiency and paint adhesion has an aluminum alloy coating and a surface treatment layer on at least one surface of its substrate.

5. A method for manufacturing an aluminum-coated hot-formed steel sheet with high heating efficiency and paint adhesion as described in any one of claims 1-4, characterized in that, The manufacturing method is as follows: coating a steel plate containing manganese and lithium sources onto an aluminum alloy coated steel plate, heating and drying it at a temperature of 80-300℃ for 5-120 seconds.

6. A method for manufacturing an aluminum-coated hot-formed steel sheet with high heating efficiency and paint adhesion as described in claim 5, characterized in that, The coating containing manganese and lithium sources also contains a binder, and the concentration of the binder in the coating is 5-20 g / L.

7. The application of an aluminum-coated hot-formed steel sheet with high heating efficiency and paint adhesion as described in any one of claims 1-6, characterized in that, Used in the manufacture of automotive parts.

8. The application according to claim 7, characterized in that, The application method is as follows: After the aluminum-coated hot-formed steel sheet with high heating efficiency and paint adhesion is made into a blank, it is heated, kept at a certain temperature, and then hot-stamped.

9. The application according to claim 8, characterized in that, The heating process has a heating rate of ≥5℃ / s.

10. The application according to claim 8 or 9, characterized in that, When the thickness of the blank is ≥1.4mm, the total heating and holding time is 3-5 minutes; when the thickness of the blank is <1.4mm, the total heating and holding time is 1-3 minutes.

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