Aluminum-silicon plated steel sheet, hot formed parts and manufacturing method thereof

Abstract

The present invention comprises a steel substrate and an aluminum-silicon plating layer plated on the surface of the steel substrate, the surface of which is further covered with a coating, the coating containing C, H, O, N, and Si elements but not containing P element, and the Si element content in the coating is 10-1000 mg / m 2 An aluminum-silicon plated steel sheet having a coating, the coating being represented by the formula: a manufacturing method for an aluminum-silicon plated steel sheet and a hot-formed part prepared using the aluminum-silicon plated steel sheet; the manufacturing method for an aluminum-silicon plated steel sheet includes the steps of steelmaking, hot rolling, cold rolling, hot dip coating, leveling, and applying paint to form a coating; the manufacturing method for a hot-formed part specifically includes the following steps: (1) cutting the aluminum-silicon plated steel sheet into blanks; (2) heat treatment in a furnace: controlling the heating rate of the blank from room temperature to 700°C at 5 to 30°C / s, and controlling the heating rate above 700°C at 1 to 10°C / s; (3) transferring the blank to a mold for hot pressing or roller press forming.

Description

[Technical Field]

[0001] The present invention relates to a steel sheet, a hot-formed part and a manufacturing method thereof, and more particularly to a plated steel sheet, a hot-formed part and a manufacturing method thereof. [Background technology]

[0002] In recent years, with the rapid development of the automobile industry, the market and users' requirements for automobiles are becoming higher and higher, and lightweighting is gradually becoming the future development trend of the automobile industry.

[0003] Currently, to meet the demand for lightweight automobiles, hot-formed steel is often used to prepare automobile structural parts and safety parts, and its usage in the market is increasing. However, the currently prepared non-plated hot-formed steel cannot meet user needs due to problems such as decarburization, oxide scale shot peening, poor dimensional accuracy, and corrosion resistance.

[0004] Therefore, in consideration of the above-mentioned drawbacks of non-plated hot-formed steel, researchers in this field have designed and developed hot-formed steel with an aluminum-silicon plated layer on its surface. The aluminum-silicon plated steel sheet designed in this way has been widely used in the field of hot-formed steel sheets due to the excellent heat resistance, corrosion resistance, and high-temperature oxidation resistance of the aluminum-silicon plated layer itself.

[0005] Currently, domestic demand for such aluminum-silicon plated hot-formed steel is approximately 800,000 tons per year. However, the inventors have found that the aluminum-silicon plating layer applied to such aluminum-silicon plated hot-formed steel also has problems, large or small, such as roller sticking in the aluminum-silicon plating layer during the hot pressing process.

[0006] Regarding the roller sticking problem, current researchers usually solve this problem by optimizing the plating layer thickness, temperature rise curve, etc.

[0007] For example, in a Chinese patent document with publication number CN101910426A, publication date December 8, 2010, and title "Method for manufacturing a pressed product and pressed product manufactured thereby," the technical solution states that in order to improve roller adhesion of the coating layer, it is necessary to control the heating rate, and in particular, the heating rate from room temperature to 700°C is 4-12°C / s. Calculating in this way, the time required for a steel sheet to be heated from room temperature to 700°C is generally 1-3 minutes, but since the austenitizing temperature is above 840°C and a certain period of heat retention is required to complete the austenitizing, the time required for the substrate to complete the austenitizing from room temperature is generally 3-6 minutes.

[0008] For example, a Chinese patent document, publication number CN106164184A, published on November 23, 2016, and titled "Method for Producing Press-Hardened Coated Steel Parts with High Production Rate," discloses hot-pressed steel with a polymer layer, in which a polymer layer is added on top of the aluminum-silicon plating layer to improve the heating rate of the aluminum-silicon plating layer. However, the polymer layer is 2 to 30 micrometers thick, while the aluminum-silicon plating layer is generally 20 micrometers or thicker. Such thick polymer and plating layers pose significant challenges in production and coiling, and the polymer layer generates a large amount of decomposition products during subsequent heat treatment, which affects furnace atmosphere control and the surface quality of the product and leads to problems such as delayed cracking.

[0009] Furthermore, for example, a Chinese patent document with publication number CN109518114A, publication date March 26, 2019, and title "Method for manufacturing hot-pressed part with aluminum-silicon alloy plating layer and hot-pressed part" discloses a method for manufacturing a hot-pressed part, but mentions using a step-by-step heating method to improve roller adhesion of the plating layer, but the effect is limited. Although this may take more time, especially for thick-gauge products, there is an ever-increasing demand for thick-gauge hot-formed steel products, and there is clear demand for them, especially for new energy battery packs and bumpers.

[0010] Therefore, considering that the currently proposed solutions in the prior art patents do not adequately solve this problem, the present inventors believe that it is of great practical significance to research means for improving the heating efficiency of hot-formed steel products while resolving the problem of roller sticking of the coating layer. Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to provide an aluminum-silicon plated steel sheet having a coating, which can be effectively used in preparing hot-formed products, not only effectively solving the problem of roller sticking of the aluminum-silicon plating layer, but also effectively improving the heating efficiency in preparing hot-formed products, and has good prospects for general application and practical application. [Means for solving the problem]

[0012] To achieve the above object, the present invention provides a steel substrate and an aluminum-silicon plating layer plated on the surface of the steel substrate, wherein the surface of the aluminum-silicon plating layer is further covered with a coating, the coating containing C, H, O, N, and Si elements but not P element, and the Si element content in the coating is 10-1000 mg / m 2 The present invention provides an aluminum-silicon plated steel sheet having a coating comprising:

[0013] In the above technical solution of the present invention, the coating on the surface of the aluminum-silicon plating layer contains Si element but does not contain P element, which tends to remain on the surface and may affect the subsequent coating solution.

[0014] Accordingly, in the coating designed according to the present invention, the main function of adding an appropriate amount of Si element is to increase the adhesion of the coating and prevent it from remaining on the surface. It should be noted that if the Si element content in the coating is too low, the beneficial effects of Si element cannot be exerted, but if the Si element content in the coating is too high, it is likely to remain on the surface. Therefore, in the present invention, the Si element content in the coating must be strictly controlled, specifically, the Si element content in the coating must be 10-1000 mg / m 2 In some embodiments, the Si element content in the coating is controlled to 200 to 1000 mg / m 2 The Si element content in the coating is controlled to 200 to 500 mg / m 2 Control to.

[0015] Furthermore, in the aluminum-silicon plated steel sheet having the coating of the present invention, the thickness of the coating is 2 micrometers or less, and is one-tenth or less of the thickness of the aluminum-silicon plated layer.

[0016] Furthermore, in the aluminum-silicon plated steel sheet having the coating according to the present invention, the thickness of the aluminum-silicon plated layer is 10 to 30 micrometers.

[0017] Furthermore, in the aluminum-silicon plated steel sheet having the coating according to the present invention, the surface roughness Ra of the steel substrate is 0.5-1.5, and Rpc is 50-100.

[0018] In the above technical solution of the present invention, it is preferable to control the surface roughness Ra of the steel substrate of the aluminum-silicon plated steel sheet having the coating to 0.5-1.5 and the Rpc to 50-100.

[0019] In this document, the definition of Ra is the standard definition, which refers to the arithmetic mean value of the absolute value of the deviation amount in the Z direction from the average line within one sampling length.

[0020] In this paper, the definition of Rpc is the standard definition, which is expressed as the number of roughness profile elements that consecutively pass through the specified upper profile cutting line c1 and lower profile cutting line c2 per unit length.

[0021] In the present invention, the reason for controlling the surface roughness Ra to 0.5 to 1.5 is mainly to further increase the adhesion of the coating and to further improve the heating rate by expanding the heat absorption area.

[0022] Accordingly, the reason for controlling the Rpc to 50-100 is mainly to improve the surface profile and increase the adhesion of the coating, thereby further expanding the heat absorption area.

[0023] In the present invention, Ra and Rpc are controlled within the above ranges by controlling the cooling rate after plating, the roller surface profile, and the leveling rate. Specifically, in the present invention, the cooling rate after plating is controlled to 5 to 30°C / s, the roller surface roughness Ra to >1.5, the Rpc to >100, and the leveling rate to 0.8 to 3%.

[0024] Furthermore, in the aluminum-silicon plated steel sheet having the coating according to the present invention, the mass percentage content of the chemical elements of the steel substrate is: C: 0.05 to 0.5%, Si: 0.01 to 2.0%, Mn: 0.3 to 3.0%, Al: 0.005 to 0.3%, Ti≦0.1%, B≦0.1%, Cr≦0.5%, Nb≦0.1%, V≦0.1%, Ni≦0.5%, Mo≦0.5%, and the balance is Fe and unavoidable impurities.

[0025] In some embodiments, the mass percentage content of C in the steel substrate is 0.05 to 0.35%.

[0026] In some embodiments, the mass percentage content of Si in the steel substrate is 0.1 to 1.0% or 0.8 to 2.0%.

[0027] In some embodiments, the mass percentage content of Mn in the steel substrate is 0.5 to 1.5% or 1.0 to 3.0%.

[0028] In some embodiments, the mass percentage content of Ti in the steel substrate is 0.01 to 0.1%.

[0029] In some embodiments, the mass percentage content of B in the steel substrate is 0.001 to 0.1%.

[0030] In some embodiments, the mass percentage content of Cr in the steel substrate is 0.1 to 0.5%.

[0031] In some embodiments, the mass percentage content of Nb in the steel substrate is 0.001 to 0.1%.

[0032] In some embodiments, the mass percentage content of Mo in the steel substrate is 0.001 to 0.2%.

[0033] In some embodiments, the mass percentage content of Ni in the steel substrate is 0.001 to 0.2%.

[0034] In some embodiments, the mass percentage content of V in the steel substrate is 0.001 to 0.1%.

[0035] Furthermore, in the aluminum-silicon plated steel sheet having the coating according to the present invention, for the inevitable impurities in the steel substrate, P ≤ 0.3% and S ≤ 0.1%.

[0036] Furthermore, in the aluminum-silicon plated steel sheet having the coating according to the present invention, the aluminum-silicon plating layer contains, in addition to Al and inevitable impurities, further Si: 6 to 11 wt%, 0 < Fe ≤ 4 wt%. In some embodiments, the content of Si is 8 to 11 wt%. In some embodiments, the content of Fe is 0.1 to 4 wt%, for example, 1 to 3 wt%.

[0037] Furthermore, in the aluminum-silicon plated steel sheet having a coating according to the present invention, the aluminum-silicon plating layer further contains Mg and / or Zn. In some embodiments, the Mn content is ≦2 wt%, for example, 0-2 wt% or 0.5-1.5 wt%. In some embodiments, the Zn content is ≦5 wt%, for example, 0-5 wt% or 2-5 wt%.

[0038] The coating further contains a filler and a resin. In some embodiments, the filler includes a carbon material and a silane coupling agent. In some embodiments, the resin includes at least one of a polyester resin, a polyurethane resin, and a polyacrylic resin. In some embodiments, the resin component includes one or more of polyurethane, polyacrylate, and polyethylene terephthalate. In some embodiments, the carbon material includes at least one of graphite, graphene, and activated carbon. In some embodiments, the mass ratio of the filler to the resin is 1:1 to 1:20, for example, 1:1 to 1:10. In some embodiments, the mass ratio of the carbon material to the silane coupling agent is 0.05 to 1; in some embodiments, the mass ratio of the carbon material to the silane coupling agent is 0.1 to 1.

[0039] Furthermore, in the aluminum-silicon plated steel sheet having the coating according to the present invention, the surface of the coating may be further coated with an oil coating.

[0040] In the above technical solutions of the present invention, the surface of the coating may be further coated with an oil coating. By applying an oil coating to the surface of the aluminum-silicon plated steel sheet having the coating, the friction between the steel sheets can be further reduced and the integrity of the coating can be maintained.

[0041] Accordingly, the present invention further discloses a method for producing an aluminum-silicon plated steel sheet having the above coating, which specifically includes the steps of steel making, hot rolling, cold rolling, hot dip galvanizing, leveling, and applying paint to form the coating.

[0042] It should be noted that the method for manufacturing a steel substrate according to the present invention includes processes such as steelmaking, hot rolling, cold rolling, and hot-dip galvanizing, and the specific process parameters for these processes may be those well known in the art. For example, the steelmaking process may include smelting and casting according to the desired composition to obtain a billet. The hot-rolling process may include rough rolling, finish rolling, and coiling, where the finish rolling temperature may be 880-930°C and the coiling temperature may be 500-650°C. The cold-rolling process includes forming a strip steel by cold rolling, where the cold-rolling deformation is 30-70%. After processing in a continuous annealing furnace, the steel may be placed in a zinc pot and hot-dip galvanized. The annealing temperature may be 670-850°C, the galvanizing solution temperature may be 640-680°C, and the cooling rate after galvanizing may be 5-30°C / s.

[0043] It should be noted that when specifically implementing the method for producing an aluminum-silicon plated steel sheet according to the present invention, when applying a paint to form the coating, the paint may be applied using various methods, such as roller coating, brush coating, electrostatic coating, etc.

[0044] Furthermore, in the method for producing an aluminum-silicon plated steel sheet having a coating according to the present invention, the mass percentage ratio of the active ingredient of the paint is: Filler: 0.5 to 30%; resin: 10 to 50%; the remainder being a solvent; provided that the filler contains a carbon material and a silane coupling agent.

[0045] Furthermore, in the method for producing an aluminum-silicon plated steel sheet having a coating according to the present invention, the mass ratio of the carbon material to the silane coupling agent is 0.05 to 1. In some embodiments, the mass ratio of the carbon material to the silane coupling agent is 0.1 to 1.

[0046] Furthermore, in the method for producing an aluminum-silicon plated steel sheet having a coating according to the present invention, the carbon material includes at least one of graphite, graphene, and activated carbon.

[0047] Furthermore, the chemical formula of the silane coupling agent is RSiX3; in this formula, X represents a hydrolyzable functional group that can generate silanol, i.e., Si(OH)3, after hydrolysis and bond with inorganic materials to form siloxane; R represents an organic group such as an alkenyl group (e.g., a vinyl group), an alkoxy group (e.g., an ethoxy group), an acid group (methacrylic acid group), an amino group, a mercapto group, etc., and an organic functional group that can undergo a coupling reaction with inorganic materials, synthetic resins, and rubbers. Exemplary Xs include halogen, C 1~6 Alkoxy groups (e.g., methoxy groups, ethoxy groups, etc.), C 1~6 Alkoxy-C 1~6 Alkyleneoxy group (e.g., methoxyethoxy group), C 1~6 Exemplary R includes alkylcarbonyloxy groups (e.g., acetoxy groups). 2~6 These include alkenyl groups, amino groups, epoxy groups, methacryloxy groups, mercapto groups, ureido groups, etc. Depending on the type of reactive group in the R group, the silane coupling agent may also be called vinyl silane, amino silane, epoxy silane, mercapto silane, methacryloxy silane, etc. Suitable silane coupling agents include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(β-methoxyethoxy)silane, etc.

[0048] Furthermore, in the method for producing an aluminum-silicon plated steel sheet having a coating according to the present invention, the resin includes at least one of polyester resin, polyurethane resin, and polyacrylic resin.

[0049] In some embodiments, the resin component comprises one or more of polyurethane, polyacrylate, and polyethylene terephthalate.

[0050] An appropriate silane coupling agent can be selected depending on the type of resin, and the carbon material and resin can be coupled to form a filler-silane coupling agent-resin coating.

[0051] Furthermore, in the method for producing an aluminum-silicon plated steel sheet having a coating according to the present invention, the solvent is water, ethanol, a ketone, an ether, or an ester. In some embodiments, the solvent is water, ethanol, or an ester. In some embodiments, the solvent is one or more of water, ethanol, diethyl ether, butanone, and ethyl acetate.

[0052] Furthermore, in the method for producing an aluminum-silicon plated steel sheet having a coating according to the present invention, the leveling rate is controlled to 0.8 to 3% in the leveling step.

[0053] Furthermore, in the method for producing an aluminum-silicon plated steel sheet having a coating according to the present invention, an oil coating may be further included after the coating application step, provided that the amount of oil coating is 300 to 1000 mg / m 2 Control to.

[0054] Another object of the present invention is to provide a hot formed part which is very convenient to prepare and does not have the problem of roller sticking.

[0055] To achieve the above object, the present invention provides a hot-formed part manufactured using the aluminum-silicon plated steel sheet of the present invention.

[0056] In order to achieve the above object, the present invention provides a hot-formed part manufactured using an aluminum-silicon plated steel sheet obtained by the manufacturing method according to the present invention.

[0057] Furthermore, in the hot-formed part according to the present invention, the microstructure comprises at least one of martensite, bainite, and ferrite.

[0058] In the hot-formed part designed according to the present invention, the microstructure of the final hot-formed part may be one or more of martensite, bainite, and ferrite, and the specific composition and content of these may depend on the chemical element composition of the steel substrate and the cooling rate of the blank in the mold from 800°C to 300°C.

[0059] Furthermore, the present invention also discloses a method for manufacturing the above-mentioned hot-formed part, and by employing this manufacturing method, desired hot-formed parts can be efficiently prepared from the aluminum-silicon plated steel sheet according to the present invention.

[0060] In order to achieve the above object, the method for producing the above hot-formed part provided by the present invention includes the following steps: (1) Cutting aluminum-silicon plated steel sheet into blanks; (2) Heat treatment in the furnace: the heating rate of the blank from room temperature to 700°C is 8~30°C / s, and the heating rate above 700°C is 1~10°C / s; (3) The blank is transferred to a mold and subjected to hot pressing or roller pressing, where the blank is cooled through the mold, and the cooling rate of the blank in the mold from 800°C to 300°C is 25°C / s or more.

[0061] In this manufacturing method designed according to the present invention, the aluminum-silicon plated steel sheet according to the present invention is cut into blanks, which are then transported to a heat treatment furnace for heat treatment, and the heating rate of the blanks from room temperature to a temperature of 700°C may be controlled to 5 to 30°C / s, for example 8 to 30°C / s, and the heating rate above 700°C may be controlled to 1 to 10°C / s. In some embodiments, the heating rate from 700 to 900°C is 1 to 10°C / s.

[0062] In the heat treatment process, the blank is transported into a heat treatment furnace and heat-treated. The heat treatment furnace temperature may be controlled to 700 to 1000°C, and the temperature may be increased stepwise, increased or decreased, or may be one or more temperatures. The maximum temperature of the heat treatment furnace may be controlled to 900 to 1000°C, and the total residence time of the blank in the heat treatment furnace may be controlled to preferably 1 to 15 minutes, for example, 1 to 10 minutes, 1 to 5 minutes, or 2 to 5 minutes. In some embodiments, the residence time of the blank at 900 to 1000°C is 1 to 5 minutes, for example, 2 to 4 minutes.

[0063] It should also be noted that in the present invention, the inventors further control the cooling rate of the blank in the mold, specifically, the cooling rate of the blank in the mold from 800°C to 300°C is controlled to 25°C / s, for example, 25-100°C / s or 25-80°C / s, to ensure that the required microstructure is obtained in the finished steel product.

[0064] Furthermore, in the method for producing a hot-formed part according to the present invention, in step (2), the total residence time of the blank in the heat treatment furnace is controlled to 1 to 15 minutes.

[0065] Furthermore, in the method for producing a hot-formed part according to the present invention, in step (3), the temperature of the blank transferred to the die is 650°C or higher, for example, 650 to 780°C, and the press speed from the start of contact between the die and the blank to the formation of the blank is controlled to 40 to 100 mm / s.

[0066] Furthermore, the method for producing a hot-formed part according to the present invention further comprises the step of producing an aluminum-silicon plated steel sheet using the method for producing an aluminum-silicon plated steel sheet having a coating according to any one of the embodiments herein. [Effects of the Invention]

[0067] The aluminum-silicon plated steel sheet, hot-formed part and manufacturing method thereof according to the present invention have the following advantages and beneficial effects compared to the prior art: (1) Compared with conventional aluminum-silicon plated steel sheets, the aluminum-silicon plated steel sheets designed according to the present invention can effectively reduce the roller adhesion of the aluminum-silicon plated layer during production and preparation, thereby extending the service life of the furnace.

[0068] (2) Compared with conventional aluminum-silicon plated steel sheets, various heating methods can be employed in preparing the aluminum-silicon plated steel sheet designed according to the present invention, and it is particularly suitable for a rapid heating mode, especially a mode of rapid initial temperature increase, and even in such a mode, it is still possible to ensure that the aluminum-silicon plated layer remains intact and does not stick to the roller.

[0069] (3) Compared with conventional aluminum-silicon plated steel sheets, when the aluminum-silicon plated steel sheets of the present invention are used to prepare hot-formed parts, the total residence time of the steel sheets in the heat treatment furnace can be reduced by adopting a rapid heating mode.

[0070] It should be noted that the core improvement of this technical solution of the present invention lies in the design of a novel coating with a different heat reflection coefficient that contributes to better heat absorption, thereby achieving a rapid increase in the temperature of the steel sheet, thus avoiding melting of the aluminum-silicon plating layer on the surface of the steel substrate and effectively reducing roller sticking.

[0071] Furthermore, after the aluminum-silicon plated steel sheet designed according to the present invention undergoes heat treatment, there are no additional or residual elements other than Al, Si, Fe, and O. The hot-formed parts prepared from the aluminum-silicon plated steel sheet through heat treatment have a more uniform and consistent appearance color, with no obvious color difference.

[0072] Furthermore, the aluminum-silicon plated steel sheet designed according to the present invention has a thin coating thickness, and when transported into a heat treatment furnace, it generates only a small amount of gas upon decomposition, resulting in little effect on the dew point inside the furnace.

[0073] The aluminum-silicon plated steel sheet according to the present invention can reduce melting of the aluminum-silicon plating layer during the heating process, thereby reducing the reaction between the molten aluminum and water vapor in the furnace and the generation of hydrogen atoms, thereby reducing the hydrogen content in parts and the risk of delayed cracking due to hydrogen. [Brief explanation of the drawings]

[0074] [Figure 1] FIG. 1 conceptually shows a conceptual diagram of temperature rise curves when an aluminum-silicon plated steel sheet according to the present invention and a conventional aluminum-silicon plated steel sheet are heated to 900° C. in a heat treatment furnace. [Figure 2] FIG. 2 is a photograph of the surface profile of the aluminum-silicon plated steel sheet according to Example 1 after undergoing heat treatment. DETAILED DESCRIPTION OF THE INVENTION

[0075] The aluminum-silicon plated steel sheet and hot-pressed part according to the present invention will be further explained and described below with reference to the drawings and specific examples, but the explanations and interpretations are not intended to unduly limit the technical solutions of the present invention.

[0076] Examples 1 to 6 and Comparative Example 1 Table 1 shows the mass percentage ratios of each chemical element in the steel substrate of the aluminum-silicon plated steel sheet used for the hot-formed parts according to Examples 1 to 6 and Comparative Example 1.

[0077] [Table 1]

[0078] In the present invention, the specific process steps of the corresponding aluminum-silicon plated steel sheets prepared in Examples 1 to 6 and Comparative Example 1 are as follows: Example 1: According to the mass percentage ratio of each chemical element shown in Table 1 above, an aluminum-silicon plated steel sheet was obtained by steelmaking, hot rolling, cold rolling, hot dip galvanizing, leveling, roller coating, and oil coating, where the leveling rate was 0.8%, the thickness of the aluminum-silicon plating layer was 20 micrometers, the coating thickness was 2 micrometers, and the oil coating amount was 300 mg / m 2 It was.

[0079] Example 2: An aluminum-silicon plated steel sheet was obtained by steelmaking, hot rolling, cold rolling, hot dip galvanizing, leveling, and roller coating according to the mass percentage ratio of each chemical element shown in Table 1. The leveling rate was 1.4%, the thickness of the aluminum-silicon plating layer was 10 micrometers, and the thickness of the coating was 0.5 micrometers.

[0080] Example 3: According to the mass percentage ratio of each chemical element shown in Table 1 above, an aluminum-silicon plated steel sheet was obtained by steelmaking, hot rolling, cold rolling, hot dip galvanizing, leveling, roller coating, and oil coating, where the leveling rate was 1.8%, the thickness of the aluminum-silicon plating layer was 27 micrometers, the coating thickness was 1.9 micrometers, and the oil coating amount was 600 mg / m 2 It was.

[0081] Example 4: According to the mass percentage ratio of each chemical element shown in Table 1 above, an aluminum-silicon plated steel sheet was obtained by steelmaking, hot rolling, cold rolling, hot dip galvanizing, leveling, roller coating, and oil coating, where the leveling rate was 3%, the thickness of the aluminum-silicon plating layer was 30 micrometers, the coating thickness was 1.9 micrometers, and the oil coating amount was 800 mg / m 2 It was.

[0082] Example 5: According to the mass percentage ratio of each chemical element shown in Table 1 above, an aluminum-silicon plated steel sheet was obtained by steelmaking, hot rolling, cold rolling, hot dip galvanizing, leveling, roller coating, and oil coating, where the leveling rate was 1.2%, the thickness of the aluminum-silicon plating layer was 24 micrometers, the coating thickness was 1.8 micrometers, and the oil coating amount was 800 mg / m 2 It was.

[0083] Example 6: According to the mass percentage ratio of each chemical element shown in Table 1 above, an aluminum-silicon plated steel sheet was obtained by steelmaking, hot rolling, cold rolling, hot dip galvanizing, leveling, roller coating, and oil coating, where the leveling rate was 1%, the thickness of the aluminum-silicon plating layer was 23 micrometers, the coating thickness was 1 micrometer, and the oil coating amount was 1000 mg / m 2 It was.

[0084] Comparative Example 1: According to the mass percentage ratio of each chemical element shown in Table 1, an aluminum-silicon plated steel sheet was obtained by steelmaking, hot rolling, cold rolling, hot dip galvanizing, leveling, and oil coating. However, the leveling rate was 0.8%, the thickness of the aluminum-silicon plated layer was 20 micrometers, there was no coating, and the amount of oil coating was 300 mg / m 2 It was.

[0085] The methods of steelmaking, hot rolling, cold rolling, annealing and hot dip galvanizing in Examples 1 to 6 and Comparative Example 1 were as follows: 1) Steelmaking: Smelting and casting were carried out according to the composition in Table 1 to obtain billets; 2) Hot rolling: including rough rolling, finish rolling and coiling, the finish rolling temperature was 880-930℃, and the coiling temperature was 500-650℃; 3) Cold rolling: The cold rolling deformation amount was 30-70%; 4) Annealing: Treated in a continuous annealing furnace, the annealing temperature was 670-850°C; 5) Hot-dip plating: After annealing, the steel was placed in a zinc pot for hot-dip plating. The plating liquid temperature was 640-680°C, and the cooling rate after plating was 5-30°C / s.

[0086] The specific process is shown in Table 2 below.

[0087] [Table 2]

[0088] To explain in detail each parameter of the aluminum-silicon plated steel sheets according to Examples 1 to 6 prepared in the present invention, the inventors further show the basic parameters of the aluminum-silicon plated steel sheets according to Examples 1 to 6 and Comparative Example 1 in Table 3 below.

[0089] Table 3 shows the basic parameters of the aluminum-silicon plated steel sheets according to Examples 1 to 6 and Comparative Example 1 prepared in the present invention.

[0090] [Table 3]

[0091] When the aluminum-silicon plated steel sheets according to Examples 1 to 6 were actually prepared, a specific plating solution had to be used in the hot-dip plating process to form an "aluminum-silicon plating layer" on the surface of the steel substrate. Similarly, after the aluminum-silicon plating layer was formed, a paint had to be applied to the surface of the aluminum-silicon plating layer to form a coating. As can be seen from this, when the aluminum-silicon plated steel sheets according to each Example were actually prepared, the design of the chemical composition of the plating solution and the chemical composition of the paint used were also very important, and the results of the design of the chemical composition of the relevant plating solution and paint are shown in Tables 4-1 and 4-2 below, respectively.

[0092] The chemical composition designs of the plating solutions and plating layers in Examples 1 to 6 are shown in Table 4-1.

[0093] [Table 4-1]

[0094] The chemical composition designs of the paints used in Examples 1 to 6 are shown in Table 4-2.

[0095] [Table 4-2]

[0096] The coating was formed by applying the paint in Table 4-2 to the surface of the aluminum-silicon plating layer. The N element in the coating was derived from the resin in the paint, and the C, H, O, and N elements in the coating were derived from the resin, solvent, and silane coupling agent in the paint. The coating in this application did not contain the P element. In this technical solution, the Si element content in the coating was adjusted to 10-1000 mg / m through the ratio and content of the silane coupling agent. 2 was controlled.

[0097] It should be noted that although a single carbon material was used as the carbon material in Examples 1 to 6 above, in other embodiments, graphite, graphene, and activated carbon may be used in combination.

[0098] In the present invention, the hot-formed parts according to Examples 1 to 6 were all prepared by the following steps: (1) A process for producing an aluminum-silicon plated steel sheet in which a coating is applied to the surface of the corresponding aluminum-silicon plating layer through steelmaking, hot rolling, cold rolling, hot dip galvanizing, leveling, and application of paint to form a corresponding coating according to the mass percentage ratio of each chemical element shown in Table 1 above.

[0099] (2) According to the required part shape, the correspondingly prepared aluminum-silicon plated steel sheet was cut into blanks.

[0100] (3) The obtained blank was transported into a heat treatment furnace and heat-treated in the furnace: the processed blank was placed in a heat treatment furnace, and the heating rate of the blank from room temperature to 700°C was controlled at 8 to 30°C / s, and the heating rate above 700°C was controlled at 1 to 10°C / s; however, the set temperature of the heat treatment furnace was 700 to 1000°C, and the temperature could be increased stepwise, increased or decreased, or at one or more temperatures, with the maximum temperature being 900 to 1000°C, and the total residence time of the blank in the heat treatment furnace was controlled to 1 to 15 min.

[0101] (4) The blank was transferred to a mold and hot pressed or roller pressed: the temperature of the blank transferred to the mold was controlled to 650°C or higher, and the blank was cooled simultaneously with the forming. The cooling rate of the blank in the mold from 800°C to 300°C was controlled to 25°C / s or higher, and the press speed from the start of contact between the mold and blank to the blank forming was controlled to 40 to 100 mm / s.

[0102] It should be noted that in the present invention, the aluminum-silicon plated steel sheets, hot-formed parts and related manufacturing processes according to the designed Examples 1 to 6 all met the design requirements of the present invention.

[0103] The relevant process parameters for the manufacturing methods of the hot-formed parts according to Examples 1 to 6 are shown in Table 5.

[0104] [Table 5]

[0105] It should be noted that in the above Table 4 of the present invention, the heat treatment temperatures of the heat treatment process in step (2) of Examples 1 to 6 are not single-point values but are all range values. This is because a heat treatment furnace is usually controlled in stages, and the temperature of each stage may be controlled independently or differently, and the temperature range described in the present invention is the distribution range of all temperatures of each stage.

[0106] In the above technical solutions of the present invention, the inventors specifically observed and studied whether or not the phenomenon of "roller sticking of the coating layer" occurred when hot-formed parts were prepared from the aluminum-silicon plated steel sheets according to each Example and Comparative Example. If the phenomenon of "roller sticking of the coating layer" occurred, it was recorded as "Yes," and if the phenomenon of "roller sticking of the coating layer" did not occur, it was recorded as "No." The relevant observation results are shown in Table 6 below.

[0107] [Table 6]

[0108] As can be seen from Table 6 above, when hot-formed parts were prepared from the aluminum-silicon plated steel sheets having the coatings according to Examples 1 to 6 obtained according to the design of the present invention, the phenomenon of "roller sticking of the coating layer" did not occur in any of them. In contrast, when hot-formed parts were prepared from the comparative aluminum-silicon plated steel sheet prepared in Comparative Example 1, the phenomenon of "roller sticking of the coating layer" occurred.

[0109] Accordingly, based on the finished hot-formed parts finally prepared from the aluminum-silicon plated steel sheets according to each example and comparative example, samples were taken from the finished hot-formed parts prepared in Examples 1 to 6 and Comparative Example 1, respectively, and the microstructures of the parts according to each example and comparative example were metallographically prepared, polished, hub-cut and etched, and then detected by metallographic microscope, and the relevant detection results are shown in Table 7 below.

[0110] [Table 7]

[0111] As can be seen from Table 7 above, in the present invention, the microstructure of the finished hot-formed parts prepared according to Examples 1 to 6 has at least one of martensite, bainite, and ferrite.

[0112] FIG. 1 conceptually shows a conceptual diagram of temperature rise curves when an aluminum-silicon plated steel sheet according to the present invention and a conventional aluminum-silicon plated steel sheet are heated to 900° C. in a heat treatment furnace.

[0113] As shown in FIG. 1, the "solid line" shown in FIG. 1 represents the aluminum-silicon plated steel sheet according to the present invention, and the "dashed line" shown in FIG. 1 represents the conventional aluminum-silicon plated steel sheet.

[0114] In this test shown in Figure 1, the thickness of both the aluminum-silicon plated steel sheet of the present invention and the conventional aluminum-silicon plated steel sheet was specifically 2.0 mm. As can be easily seen from the comparison, the temperature rise rate of the aluminum-silicon plated steel sheet of the present invention, particularly the temperature rise rate from room temperature to 700°C, was significantly higher than that of the conventional aluminum-silicon plated steel sheet.

[0115] FIG. 2 is a photograph of the surface profile of the aluminum-silicon plated steel sheet according to Example 1 after undergoing heat treatment.

[0116] As shown in FIG. 2, in this embodiment of Example 1 designed according to the present invention, the aluminum-silicon plated steel sheet according to the present invention had an uneven and irregular profile on its surface after undergoing the heat treatment process in step (2) of the manufacturing method of the present invention.

[0117] Furthermore, the combinations of the technical features in this application are not limited to the combinations described in the claims of this application or the combinations described in the specific examples, and as long as there are no contradictions, all technical features described in this application can be freely combined or combined in any form.

[0118] Furthermore, it should be noted that the above-mentioned embodiments are merely specific embodiments of the present invention, and the present invention is not limited to the above-mentioned embodiments, and it is clear that any similar changes or modifications that can be directly derived or easily conceived by those skilled in the art from the disclosure of the present invention are included in the protection scope of the present invention.

Claims

1. The present invention comprises a steel substrate and an aluminum-silicon plating layer plated on the surface of the steel substrate, the surface of the aluminum-silicon plating layer being further coated with a coating, the coating containing C, H, O, N, and Si elements but not containing P element, and the Si element content in the coating is 10 to 1000 mg / m ２ An aluminum-silicon plated steel sheet having a coating, characterized in that:

2. 2. The coated aluminum-silicon plated steel sheet according to claim 1, wherein the thickness of the coating is 2 micrometers or less and is one-tenth or less of the thickness of the aluminum-silicon plated layer.

3. 2. The coated aluminum-silicon plated steel sheet according to claim 1, wherein the thickness of the aluminum-silicon plated layer is 10 to 30 micrometers.

4. 2. The coated aluminum-silicon plated steel sheet according to claim 1, wherein the surface roughness Ra of the steel substrate is 0.5-1.5 and Rpc is 50-100.

5. The mass percentage content of chemical elements in the steel substrate is: C: 0.05 to 0.5%, Si: 0.01 to 2.0%, Mn: 0.3 to 3.0%, Al: 0.005 to 0.3%, Ti≦0.1%, B≦0.1%, Cr≦0.5%, Nb≦0.1%, V≦0.1%, Ni≦0.5%, Mo≦0.5%, and the balance being Fe and unavoidable impurities; Preferably, the unavoidable impurities are P≦0.3% and S≦0.1%.

2. An aluminum-silicon plated steel sheet having the coating according to claim 1.

6. 2. The coated aluminum-silicon plated steel sheet according to claim 1, wherein the aluminum-silicon plating layer contains, in addition to Al and unavoidable impurities, further contains Si: 6 to 11 wt %, 0<Fe≦4 wt %; and optionally, the aluminum-silicon plating layer further contains Mg and / or Zn elements.

7. The aluminum-silicon plated steel sheet having a coating according to claim 1, wherein the coating contains a filler and a resin; preferably, the filler contains a carbon material and a silane coupling agent; preferably, the resin contains at least one of a polyester resin, a polyurethane resin, and a polyacrylic resin; preferably, the carbon material contains at least one of graphite, graphene, and activated carbon; preferably, the mass ratio of the filler to the resin is 1:1 to 1:20; and preferably, the mass ratio of the carbon material to the silane coupling agent is 0.05 to 1.

8. 2. The coated aluminum-silicon plated steel sheet according to claim 1, wherein the surface of the coating is further coated with an oil coating.

9. 8. A method for producing an aluminum-silicon plated steel sheet having a coating according to claim 1, comprising the steps of steelmaking, hot rolling, cold rolling, hot dip galvanizing, leveling, and applying a paint to form the coating.

10. The mass percentage ratio of the active ingredient of the paint is Filler: 0.5 to 30%; Resin: 10 to 50%; The remainder is a solvent; provided that the filler contains a carbon material and a silane coupling agent. A method for producing an aluminum-silicon plated steel sheet having the coating according to claim 9.

11. The method for producing an aluminum-silicon plated steel sheet having a coating according to claim 10, wherein the mass ratio of the carbon material to the silane coupling agent is 0.05 to 1.

12. The method for producing an aluminum-silicon plated steel sheet having a coating according to claim 10, wherein the carbon material includes at least one of graphite, graphene, and activated carbon.

13. The method for producing an aluminum-silicon plated steel sheet having a coating according to claim 10, wherein the resin includes at least one of a polyester resin, a polyurethane resin, and a polyacrylic resin.

14. 11. The method for producing a coated aluminum-silicon plated steel sheet according to claim 10, wherein the solvent is water, ethanol, a ketone, an ether, or an ester.

15. 10. The method for producing an aluminum-silicon plated steel sheet having a coating according to claim 9, wherein the leveling rate is controlled to 0.8 to 3% in the leveling step.

16. After the coating application step, an oil coating is further included, provided that the amount of oil coating is 300 to 1000 mg / m ２ 10. A method for producing an aluminum-silicon plated steel sheet having a coating according to claim 9, wherein the temperature is controlled to be equal to or higher than the temperature of the aluminum-silicon plated steel sheet.

17. A hot-formed part manufactured using the aluminum-silicon plated steel sheet according to any one of claims 1 to 8.

18. A hot-formed part manufactured using an aluminum-silicon plated steel sheet obtained by the manufacturing method according to any one of claims 9 to 16.

19. 19. The hot-formed part according to claim 17 or 18, characterized in that its microstructure comprises at least one of martensite, bainite and ferrite.

20. A method for producing a hot formed part according to any one of claims 17 to 19, characterized in that it comprises the following steps: (1) Cutting aluminum-silicon plated steel sheet into blanks; (2) Heat treatment in a furnace: The heating rate of the blank from room temperature to 700°C is controlled to 5 to 30°C / s, preferably 8 to 30°C / s, and the heating rate above 700°C is controlled to 1 to 10°C / s; (3) The blank is transferred to a mold and subjected to hot pressing or roller pressing, wherein the blank is cooled through the mold, and the cooling rate of the blank in the mold from 800°C to 300°C is 25°C / s or more.

21. 22. The method for producing a hot-formed part according to claim 21, wherein in step (2), the total residence time of the blank in the heat treatment furnace is controlled to 1 to 15 minutes.

22. 22. The method for producing a hot-formed part according to claim 21, wherein in step (3), the temperature of the blank transferred to the die is set to 650°C or higher, the blank is cooled simultaneously with forming, and the press speed from the start of contact between the die and the blank to blank forming is controlled to 40 to 100 mm / s.

Images