Hot stamping assembly and manufacturing method thereof

Abstract

The present invention provides a method for manufacturing a hot-stamped component, the method comprising the steps of: forming a blank by cutting a plated steel sheet having a plating layer formed on at least one surface of a base material; and heating the blank in a heating furnace comprising a plurality of sections having different temperature ranges, in which the step of heating the blank comprises: a multi-stage heating step of stepwise heating the blank; and a soaking heating step of heating the multi-stage heated blank at a temperature of Ac3 to 910 DEG C, and the temperature (an) of the soaking heating step and the total heating time (bn) of the heating step of the blank satisfy a relational expression. Lt; a relational expression gt; 62 < = 91.81 + K-0. 022 * an-0. 23 * bn (In the relational expression, K represents a material correction coefficient. ).

Description

Technical Field

[0001] The invention relates to a hot stamping component and a manufacturing method thereof. Background Art

[0002] As global environmental and fuel economy regulations become more stringent, the demand for lighter vehicle materials is increasing. Therefore, research and development of ultra-high strength steel and hot stamping steel has been actively conducted.

[0003] Generally speaking, the hot stamping process includes heating / forming / cooling / trimming, and the phase transformation and microstructural changes of the material during the process can be utilized. In order to improve the toughness of hot stamping steel, research has been actively carried out, with the focus on improving the toughness of the base material by using alloying elements.

[0004] However, changing or adding alloying elements may result in increased costs, thus raising questions about economic feasibility.

[0005] As a related art, there is Korean Patent Publication No. 10-2021-0129902 (titled “Hot stamping component and method of manufacturing the same”). Summary of the invention

[0006] Technical issues

[0007] Embodiments of the present invention may improve the bending characteristics of a manufactured hot stamped part by ensuring that the temperature in the soaking heating operation and the total heating time in the heating operation satisfy a preset relationship.

[0008] Solution to the problem

[0009] An embodiment of the present invention provides a method for manufacturing a hot stamping part, the method comprising: forming a blank by cutting a plated steel sheet having a plated layer formed on at least one surface of a base material; and heating the blank in a heating furnace including a plurality of sections having different temperature ranges, wherein the heating of the blank comprises: a multi-stage heating operation of heating the blank in stages; and a soaking heating operation of soaking the staged heated blank at a temperature of Ac3 to 910° C., and the temperature a in the soaking heating operation is n The total heating time b in the heating of the blank n The following relationship is satisfied.

[0010] <Relational formula>

[0011] 62≤91.81+K-0.022×a n -0.23×b n

[0012] (In the above relationship, K represents the material correction factor.)

[0013] In this embodiment, the total heating time b in heating the blank is n It can be from 2 min to 20 min.

[0014] In this embodiment, the material correction factor K can be 0.71×c n -0.025×d n , where c n can represent the dew point of the annealing furnace of the base material, and d n It can indicate the linear speed of the annealing furnace of the base material.

[0015] In this embodiment, the dew point c of the annealing furnace of the base material is n It can be between -15°C and +15°C.

[0016] In this embodiment, the linear speed d of the annealing furnace of the base material is n It can be from 30 mpm to 200 mpm.

[0017] In this embodiment, the annealing temperature of the base material may be 750°C to 900°C.

[0018] In the present embodiment, annealing of the base material may be performed in a gas atmosphere including 0.5 volume % to 25 volume % of hydrogen and the remainder of nitrogen.

[0019] In this embodiment, a decarburized layer may also be formed on the base material.

[0020] In this embodiment, the thickness of the decarburized layer may be 10 μm to 100 μm.

[0021] In this embodiment, the average hardness of the decarburized layer may be less than or equal to 80% of the average hardness at a point 1 / 4 away from the surface of the base material.

[0022] In the present embodiment, the plating layer may be a zinc (Zn)-based plating layer or an aluminum (Al)-based plating layer.

[0023] In this embodiment, the thickness of the plating layer may be 5 μm to 30 μm.

[0024] In the present embodiment, the method may further include: after the heating of the blank, conveying the heated blank; forming a molded body by pressing the conveyed blank using a mold; and cooling the formed molded body.

[0025] Another embodiment of the present invention provides a hot stamping component, comprising: a base material; a decarburized layer formed on the base material; and a plating layer formed on the decarburized layer, wherein the hot stamping component has a tensile strength (TS) of 1680 MPa to 2000 MPa, a yield strength (YP) of 1150 MPa to 1500 MPa, and an elongation (EL) of 4% to 10%.

[0026] In this embodiment, the average hardness of the decarburized layer may be less than or equal to 70% of the average hardness at a point 1 / 4 away from the surface of the base material.

[0027] In the present embodiment, the content of carbon included in the plating layer may be less than or equal to 50% of the content of carbon included in the base material.

[0028] In the present embodiment, the hot stamped part may have a microstructure including a martensite fraction of 90% or more.

[0029] In this embodiment, the thickness of the decarburized layer may be 10 μm to 100 μm.

[0030] In this embodiment, the thickness of the plating layer may be 7 μm to 40 μm.

[0031] Other aspects, features and advantages besides those described above will become apparent from the following detailed description, claims and accompanying drawings which serve to enable the present invention to be practiced.

[0032] Advantageous Effects of the Invention

[0033] According to the embodiments of the present invention as described above, by ensuring that the temperature in the soaking heating operation and the total heating time in the operation of heating the blank satisfy a preset relationship, the toughness of the manufactured hot stamping part can be improved.

[0034] In addition, according to an embodiment of the present invention, the toughness of a manufactured hot stamping part may be improved by increasing the dew point of the annealing furnace to form a decarburized layer on the surface of the base material. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a cross-sectional view schematically showing a hot stamped part according to an embodiment of the present invention.

[0036] Figure 2 is a flow chart schematically illustrating a method of manufacturing a hot stamped part according to an embodiment of the present invention.

[0037] Figures 3 to 5 is a cross-sectional view schematically illustrating a method of manufacturing a hot stamping part according to an embodiment of the present invention.

[0038] Figure 6 is a flow chart schematically illustrating a hot stamping operation according to an embodiment of the present invention.

[0039] Figure 7 is a flow chart schematically illustrating a heating operation according to an embodiment of the present invention.

[0040] Figure 8 is a diagram of a heating furnace including a plurality of zones for describing a heating operation of a method for manufacturing a hot stamping part according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] Since the present invention allows various changes and a large number of embodiments, specific embodiments will be shown in the drawings and described in detail. Advantages and features of the present invention and methods for achieving them will become clear through the embodiments described in detail below with reference to the drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms.

[0042] In the following embodiments, terms such as “first”, “second”, etc. are used only to distinguish one component from another component, and such components should not be limited by the terms.

[0043] In the following embodiments, a singular expression also includes a plural meaning as long as it is not contradictory with the context.

[0044] In the following embodiments, the terms “including”, “comprising”, “having” and the like used herein indicate the existence of the features or components described, but do not exclude the existence or addition of one or more other features or components.

[0045] In the following embodiments, when a layer, region or component is referred to as being “on” another layer, region or component, it may be directly or indirectly on another layer, region or component, that is, one or more intermediate layers, regions or components may be present therebetween.

[0046] For the convenience of description, the size of the components in the drawings may be enlarged or reduced. For example, since the size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of description, the present invention is not necessarily limited to those shown in the drawings.

[0047] In the present specification, "A and / or B" means A, B, or A and B. In addition, in the present specification, "at least one of A and B" means A, B, or A and B.

[0048] In the following embodiments, when a wire is referred to as "extending in a first direction or a second direction", the wire may extend not only in a straight line shape but also in a zigzag or curved shape in the first direction or the second direction.

[0049] In the following embodiments, "in a plan view" or "on a plane" means observing the target portion from the top, and the phrase "in a cross-sectional view" or "on a cross section" means observing a cross section formed by vertically cutting the target portion from the side. In the following embodiments, when two or more elements are referred to as "overlapping each other", they may overlap each other "on a plane" or "on a cross section".

[0050] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and the same or corresponding components will be denoted by the same reference numerals when describing with reference to the accompanying drawings.

[0051] Figure 1 is a cross-sectional view schematically showing a hot stamped part according to an embodiment of the present invention.

[0052] Reference Figure 1 The hot stamping part 1 according to the embodiment may include a base material 100, a decarburized layer 200, and a plating layer 300. The base material 100, the decarburized layer 200, and the plating layer 300 may be sequentially stacked in a thickness direction of the hot stamping part 1.

[0053] In one embodiment, the base material 100 may include carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), boron (B), the balance of iron (Fe), and other inevitable impurities. For example, the base material 100 may include about 0.25 wt% to about 0.5 wt% of carbon (C), about 0.1 wt% to about 0.8 wt% of silicon (Si), about 0.3 wt% to about 3.0 wt% of manganese (Mn), 0 wt% to about 0.05 wt% of phosphorus (P), 0 wt% to about 0.01 wt% of sulfur (S), about 0.0005 wt% to about 0.005 wt% of boron (B), the balance of iron (Fe), and other inevitable impurities.

[0054] In addition, the base material 100 may further include one or more of titanium (Ti), niobium (Nb) and vanadium (V). In addition, the base material 100 may further include chromium (Cr), molybdenum (Mo) and nickel (Ni).

[0055] The matrix material 100 may further include one or more of titanium (Ti), niobium (Nb), and vanadium (V), and the sum of these may be about 0.01 wt % to about 0.1 wt %. For example, the matrix material 100 may include titanium (Ti) and niobium (Nb), and the sum of the weight percentages of titanium (Ti) and niobium (Nb) contained in the matrix material 100 may be about 0.01 wt % to about 0.1 wt %.

[0056] In addition, the base material 100 may further include about 0.01 wt % to about 1.0 wt % of chromium (Cr), about 0.01 wt % to about 1.0 wt % of molybdenum (Mo), and about 0.001 wt % to about 1.0 wt % of nickel (Ni).

[0057] Carbon (C) is the main element that determines the strength and hardness of steel, and carbon can be added to ensure the tensile strength of steel after hot stamping (or hot pressing) process. In addition, carbon (C) can be added to ensure the hardenability characteristics of steel. In one embodiment, based on the gross weight of base material 100, carbon (C) can be included in an amount of about 0.25 wt % to about 0.5 wt %. In the case where carbon (C) is included in an amount less than about 0.25 wt % based on the gross weight of base material 100, it may be difficult to achieve the desired mechanical strength. On the contrary, in the case where carbon (C) is included in an amount greater than about 0.5 wt % based on the gross weight of base material 100, the problem of reduced toughness of steel or the problem of controlling steel may be caused.

[0058] Silicon (Si) can be used as a ferrite stabilizing element in the matrix material 100. Silicon (Si) can improve ductility by purifying ferrite and improve the carbon concentration in austenite by inhibiting the formation of low-temperature carbides. In addition, silicon (Si) can be a key element in hot rolling, cold rolling and hot stamping structural homogenization (control of pearlite and manganese segregation) and fine dispersion of ferrite. In one embodiment, based on the gross weight of the matrix material 100, silicon (Si) can be included in an amount of about 0.1 wt % to about 0.8 wt %. In the case where silicon (Si) is included in an amount less than about 0.1 wt % based on the gross weight of the matrix material 100, the above functions may not be fully demonstrated. On the contrary, in the case where silicon (Si) is included in an amount greater than about 0.8 wt % based on the gross weight of the matrix material 100, the hot rolling load and the cold rolling load may increase, the red oxide scale in the hot rolling may become excessive, and the bonding properties may deteriorate.

[0059] Manganese (Mn) may be added to improve hardenability and strength during heat treatment. In one embodiment, manganese (Mn) may be included in an amount of about 0.3 wt % to about 3.0 wt % based on the gross weight of the base material 100. In the case where manganese (Mn) is included in an amount less than about 0.3 wt % based on the gross weight of the base material 100, due to insufficient hardenability, after hot stamping, the quality of the resulting material will likely be insufficient (insufficient hard phase fraction). On the contrary, in the case where manganese (Mn) is included in an amount greater than about 3.0 wt % based on the gross weight of the base material 100, due to manganese segregation or pearlite bands, ductility and toughness may be reduced, which may result in a decrease in bending properties and may result in an uneven microstructure.

[0060] Phosphorus (P) is an element that is easily segregated and may impair the toughness of steel. In one embodiment, phosphorus (P) may be included in an amount of 0 wt % to about 0.05 wt % based on the total weight of the base material 100. In the case where phosphorus (P) is included in an amount within the above range based on the total weight of the base material 100, the toughness of the steel may be prevented from being deteriorated. On the contrary, in the case where phosphorus (P) is included in an amount greater than 0.05 wt % based on the total weight of the base material 100, cracks may occur during processing, and iron phosphide compounds may be formed, resulting in a decrease in the toughness of the steel.

[0061] Sulfur (S) may be an element that impairs workability and physical properties. In one embodiment, sulfur (S) may be included in an amount of 0 wt % to about 0.01 wt % based on the total weight of the base material 100. In the case where sulfur (S) is included in an amount greater than about 0.01 wt % based on the total weight of the base material 100, hot workability may be reduced, and surface defects (e.g., cracks) may occur due to the formation of larger inclusions.

[0062] Boron (B) is added to ensure the hardenability and strength of the steel by ensuring a martensitic structure, and can have a grain refinement effect by increasing the austenite grain growth temperature. In one embodiment, boron (B) may be included in an amount of about 0.0005 wt % to about 0.005 wt % based on the total weight of the base material 100. In the case where boron (B) is included in an amount within the above range based on the total weight of the base material 100, the occurrence of hard grain boundary embrittlement can be prevented, and high toughness and bendability can be ensured.

[0063] Titanium (Ti) can be added to increase hardenability and improve material quality by forming precipitates after hot stamping heat treatment. In addition, titanium (Ti) can effectively promote the refinement of austenite grains by forming precipitates such as Ti (C, N) at high temperatures.

[0064] Niobium (Nb) may be added to improve strength and toughness by reducing the martensite lath bundle size.

[0065] Vanadium (V) may be added to improve the strength of steel through a precipitation strengthening effect caused by the formation of precipitates.

[0066] In one embodiment, titanium (Ti), niobium (Nb), and vanadium (V) may be optionally included in the base material 100. Here, in the case where at least one of titanium (Ti), niobium (Nb), and vanadium (V) is included in the base material 100, the total amount of at least one component of titanium (Ti), niobium (Nb), and vanadium (V) may be about 0.01 wt % to about 0.1 wt %.

[0067] Chromium (Cr) may be added to improve the hardenability and strength of the steel. In one embodiment, chromium (Cr) may be included in an amount of about 0.01 wt % to about 1.0 wt % based on the total weight of the base material 100. When chromium (Cr) is included in an amount within the above range based on the total weight of the base material 100, the hardenability and strength of the steel may be improved, an increase in production costs may be prevented, and a decrease in toughness of the steel may be prevented.

[0068] Molybdenum (Mo) can contribute to improving strength by suppressing coarsening of precipitates and improving hardenability during hot rolling and hot stamping. Molybdenum (Mo) may be included in an amount of about 0.01 wt % to about 1.0 wt % based on the total weight of the base material 100. When molybdenum (Mo) is included in an amount within the above range based on the total weight of the base material 100, an excellent effect of suppressing coarsening of precipitates and improving hardenability during hot rolling and hot stamping may be exhibited.

[0069] Nickel (Ni) can be added to improve hardenability and strength. In addition, nickel (Ni) is an austenite stabilizing element that can help improve elongation by controlling austenite transformation. In one embodiment, based on the gross weight of the base material 100, nickel (Ni) can be included in an amount of about 0.001 wt % to about 1.0 wt %. In the case where nickel (Ni) is included in an amount less than about 0.001 wt % based on the gross weight of the base material 100, it may be difficult to properly achieve the above effect. In the case where nickel (Ni) is included in an amount greater than about 1.0 wt % based on the gross weight of the base material 100, toughness may be reduced, cold workability may be reduced, and the manufacturing cost of the product may increase.

[0070] In one embodiment, the base material 100 may have a microstructure including about 90% or more of martensite. In detail, the base material 100 may include about 90% or more of martensite, and less than about 10% of other remaining inevitable structures and precipitates.

[0071] In one embodiment, the decarburized layer 200 may be disposed on the base material 100. In the case where the decarburized layer 200 is formed on the base material 100, the toughness of the hot stamped part 1 including them may be improved.

[0072] A layer having a hardness of about 70% or less compared to the average hardness of a point about 1 / 4 from the surface of the base material 100 may be defined as the decarburized layer 200. Alternatively, a layer having a hardness of about 70% or less compared to the average hardness of a point about 1 / 4 from the surface of the hot stamping part 1 may be defined as the decarburized layer 200. That is, the average hardness of the decarburized layer 200 may be about 70% or less compared to the average hardness of a point about 1 / 4 from the surface of the base material 100 or the surface of the hot stamping part 1. In other words, the average hardness of the decarburized layer 200 may be about 70% or less of the average hardness of a point about 1 / 4 from the surface of the base material 100 or the surface of the hot stamping part 1.

[0073] The decarburized layer 200 may be arranged to have a thickness t1 of about 10 μm to about 100 μm in the thickness direction of the hot stamping part 1. In the case where the thickness t1 of the decarburized layer 200 is about 10 μm or less, the effect of improving toughness may be minimal, and in the case where the thickness t1 of the decarburized layer 200 is about 100 μm or more, the thickness of the decarburized layer 200 may be too thick, resulting in a decrease in the strength of the hot stamping part 1 including the decarburized layer 200. Therefore, in the case where the thickness t1 of the decarburized layer 200 is about 10 μm to about 100 μm, the toughness of the hot stamping part 1 may be improved while preventing or minimizing a decrease in the strength of the hot stamping part 1.

[0074] In one embodiment, the plating layer 300 may be disposed on the decarburized layer 200. The plating layer 300 may be a zinc (Zn)-based plating layer or an aluminum (Al)-based plating layer. For example, the plating layer 300 may include zinc (Zn) and / or aluminum (Al).

[0075] In one embodiment, in the case where the coating 300 is arranged as a zinc (Zn)-based coating, the coating 300 may include iron (Fe), aluminum (Al), manganese (Mn), silicon (Si), the balance of zinc (Zn) and other inevitable impurities. For example, the coating 300 may include about 10% to about 70% by weight of iron (Fe), 0% to about 5% by weight of aluminum (Al), 0% to about 1% by weight of manganese (Mn), 0% to about 1% by weight of silicon (Si), the balance of zinc (Zn) and other inevitable impurities. In addition, the coating 300 may also include carbon (C). In this case, the content of carbon (C) included in the coating 300 may be 50% or less of the content of carbon (C) included in the base material 100. For example, in the case where the base material 100 includes about 0.25% to about 0.5% by weight of carbon (C), the coating 300 may include 0% to about 0.25% by weight of carbon (C).

[0076] The plating layer 300 may be arranged to have a thickness t2 of about 7 μm to about 40 μm in the thickness direction of the hot stamping part 1. In the case where the thickness t2 of the plating layer 300 is about 7 μm or less, the sacrificial effect peculiar to zinc may be reduced, and in the case where the thickness t2 of the plating layer 300 is about 40 μm or more, the thickness of the plating layer 300 may be too thick, resulting in a reduction in the toughness of the hot stamping part 1 including the plating layer 300. Therefore, in the case where the thickness t2 of the plating layer 300 is about 7 μm to about 40 μm, the surface of the base material (or steel material) may be protected while preventing or minimizing the reduction in the toughness of the hot stamping part 1.

[0077] In one embodiment, the hot stamping part 1 can have a tensile strength (TS) of about 1680 MPa to about 2000 MPa, a yield strength (YP) of about 1150 MPa to about 1500 MPa, and an elongation (EL) of about 4% to about 10%. In addition, the hot stamping part 1 can have a VDA (Verband der Automobilindustrie) bending angle of about 60° or more. Here, the VDA bending angle can be measured according to the VDA standard (VDA238-100).

[0078] Therefore, the inventors of the present invention have found Relationship 1 through excessive repeated experiments, which enables the hot stamped part 1 to have a VDA bending angle of about 60° or more. In one embodiment, the hot stamped part 1 may satisfy the following Relationship 1.

[0079] <Relation 1>

[0080] 60≤176.92+1.25×c m -0.15×a m -0.52×b m

[0081] In equation 1, a m represents the temperature during the soaking heating operation, b m represents the total heating time in the heating operation (for example, the total heating time in the operation of heating the blank), c m Indicates the thickness of the decarburized layer.

[0082] In equation 1, a m It can represent the temperature in the soaking heating operation. The temperature unit in the soaking heating operation can be ℃, and a m The value of may represent the value of the temperature in °C during the soaking heating operation. For example, when the temperature during the soaking heating operation is 900 °C, a m The value can be 900.

[0083] In equation 1, bm may represent the total heating time in the operation of heating the blank, the unit of the total heating time in the operation of heating the blank may be minutes (min), and b m b may represent the total heating time in minutes in the operation of heating the blank. For example, if the total heating time in the operation of heating the blank is 5 minutes, b m The value of can be 5.

[0084] In equation 1, c m It can represent the thickness of the decarburized layer. The unit of the thickness of the decarburized layer can be μm, and c m It can be expressed in μm. For example, when the thickness of the decarburized layer is 40 μm, c m The value can be 40.

[0085] In one embodiment, the thickness c of the decarbonized layer 200 is m , Temperature a during the soaking heating operation m and the total heating time b in the operation of heating the blank m The above relationship 1 can be satisfied. Here, the thickness c of the decarburized layer 200 is m The thickness may be from about 10 μm to about 100 μm, and the temperature a in the soaking heating operation may be from about 10 μm to about 100 μm. m It can be from about Ac3 to about 910°C, and the total heating time b in the operation of heating the blank m It may be from about 2 min to about 20 min.

[0086] The thickness c of the decarburized layer 200 m , Temperature a during the soaking heating operation m and the total heating time b in the operation of heating the blank m When the above relational expression 1 is satisfied, the toughness of the manufactured hot stamping component 1 can be improved. m , Temperature a during the soaking heating operation m and the total heating time b in the operation of heating the blank m When the above relational expression 1 is satisfied, the toughness of the manufactured hot stamping part 1 can have a VDA bending angle of about 60° or more. m , Temperature a during the soaking heating operation m and the total heating time b in the operation of heating the blank m When the above Relationship 1 is satisfied, the manufactured hot stamping part 1 may have a tensile strength (TS) of about 1680 MPa to about 2000 MPa, a yield strength (YP) of about 1150 MPa to about 1500 MPa, and an elongation (EL) of about 4% to about 10%.

[0087] Figure 2 is a flow chart schematically illustrating a method of manufacturing a hot stamping part according to an embodiment of the present invention, and Figures 3 to 5 is a cross-sectional view schematically illustrating a method of manufacturing a hot stamping part according to an embodiment of the present invention.

[0088] Reference Figures 2 to 5 According to one embodiment, the method of manufacturing a hot stamping part may include a hot rolling operation S100, a cooling / coiling operation S200, a cold rolling operation S300, an annealing operation S400, a plating operation S500, and a hot stamping operation S600.

[0089] First, you can use Figure 1 The base material 100 (e.g., a steel billet) prepared from the above-mentioned components is subjected to a reheating operation. In the operation of reheating the steel billet, the steel billet obtained by the continuous casting process can be reheated at a certain temperature so that the components segregated during the casting process can be redissolved. In one embodiment, the slab reheating temperature (SRT) may be about 1200°C to about 1400°C. When the slab reheating temperature (SRT) is lower than 1200°C, the components segregated during the casting process cannot be fully redissolved, and therefore, the homogenization effect of the alloying elements may not be significantly achieved, and the solid solution effect of titanium (Ti) may not be significantly achieved. A higher slab reheating temperature (SRT) is conducive to homogenization, however, when the slab reheating temperature (SRT) is higher than about 1400°C, the austenite grain size may increase, making it difficult to ensure strength, while increasing the manufacturing cost of the steel plate due to the excessive heating process.

[0090] In the hot rolling operation S100, the reheated base material 100 may be hot rolled at a certain finishing exit temperature. The hot rolled steel sheet may be manufactured by the hot rolling operation S100. In one embodiment, the finishing exit temperature (FDT) may be from about 880°C to about 950°C. Here, when the finishing exit temperature (FDT) is lower than about 840°C, it may be difficult to ensure the workability of the steel sheet due to the appearance of a mixed crystal structure caused by rolling in irregular regions, the workability may be deteriorated due to the uneven microstructure, and the flowability may occur during the hot rolling process due to the rapid phase change. When the finishing exit temperature (FDT) is higher than about 950°C, the austenite grains may coarsen and the TiC precipitates may coarsen, which may deteriorate the performance of the hot stamping parts.

[0091] In the cooling / coiling operation S200, the hot-rolled base material 100 may be cooled to a certain coiling temperature (CT) and then coiled. In one embodiment, the coiling temperature in the cooling / coiling operation S200 may be about 550°C to about 800°C. The coiling temperature affects the redistribution of carbon (C), and in the case where the coiling temperature is lower than about 550°C, the low-temperature phase fraction may increase due to overcooling, which may increase the strength, the rolling load during the cold rolling process may be large, and the ductility may decrease rapidly. On the contrary, in the case where the coiling temperature is higher than about 800°C, due to irregular grain growth or excessive grain growth, deterioration of formability and deterioration of strength may occur.

[0092] In the cold rolling operation S300, the coiled base material 100 may be unwound, pickled, and then cold rolled. Here, pickling may be performed to remove the oxide scale of the coiled steel sheet (or base material) (i.e., the hot rolled coil manufactured by the above hot rolling process). A cold rolled steel sheet may be manufactured by the cold rolling operation S300.

[0093] In the annealing operation S400, the cold rolled base material 100 may be annealed at a temperature of about 700° C. or higher. For example, the annealing operation S400 may include an operation of heating the cold rolled base material 100 and cooling the heated base material 100 at a certain cooling rate.

[0094] In one embodiment, the base material may be annealed in an annealing operation S400. The annealing operation S400 may be performed in an annealing furnace.

[0095] The annealing of the base material 100 can be carried out in a gas atmosphere containing about 0.5 volume % to about 25 volume % of hydrogen and the remaining nitrogen. At this time, water can be injected into the annealing furnace together with the hydrogen and nitrogen. When water is injected into the annealing furnace, the dew point of the annealing furnace can be increased. Therefore, the dew point of the annealing furnace can be adjusted by adjusting the amount of water injected into the annealing furnace.

[0096] In addition, when the dew point of the annealing furnace is increased, a decarburized layer 200 may be formed on the base material 100. For example, carbon may be lost from the surface of the base material 100 to form the decarburized layer 200. At this time, the thickness t3 of the decarburized layer 200 formed on the surface of the base material 100 in the thickness direction of the base material 100 may be about 10 μm to about 100 μm. In the case where the thickness t3 of the decarburized layer 200 is 10 μm or less, the thickness t3 of the decarburized layer 200 is too thin, resulting in a minimal effect of improving the toughness of the manufactured hot stamping part, and in the case where the thickness t3 of the decarburized layer 200 is 100 μm or more, the thickness of the decarburized layer 200 is too thick, resulting in a decrease in the strength of the manufactured hot stamping part. Therefore, in the case where the thickness t3 of the decarburized layer 200 is about 10 μm to about 100 μm, the toughness of the manufactured hot stamping part 1 can be improved while preventing or minimizing the reduction in the strength of the hot stamping part 1.

[0097] In one embodiment, a layer having a hardness of about 80% or less compared to the average hardness of a point about 1 / 4 from the surface of the base material 100 may be defined as the decarburized layer 200. That is, compared to the average hardness of a point about 1 / 4 from the surface of the base material 100, the average hardness of the decarburized layer 200 may be about 80% or less.

[0098] In one embodiment, the dew point of the annealing furnace for annealing the base material 100 may be about -15°C to about +15°C. In the case where the dew point of the annealing furnace is -15°C or lower, the thickness t3 of the decarburized layer 200 formed may be too thin, resulting in minimal effect of improving the toughness of the manufactured hot stamping part, and in the case where the dew point of the annealing furnace is +15°C or higher, operability may be reduced due to oxidation of the equipment. For example, in order to increase the dew point of the annealing furnace, a large amount of water needs to be supplied to the annealing furnace, however, when a large amount of water is supplied to the annealing furnace, the equipment of the annealing furnace may be oxidized, and cleaning the annealing furnace may take a lot of time, which may reduce operability. Therefore, by ensuring that the dew point of the annealing furnace for annealing the base material 100 is in the range of about -15°C to about +15°C, the toughness of the manufactured hot stamping part can be improved while improving the efficiency of the manufacturing process.

[0099] In one embodiment, the line speed of the annealing furnace for annealing the base material 100 may be about 30 meters per minute (mpm) to about 200 mpm. When the line speed of the annealing furnace is 30 mpm or less, the conveying speed of the base material 100 may be too slow, which may cause a sharp drop in productivity, and when the line speed of the annealing furnace is 200 mpm or more, the conveying speed of the base material 100 may be too fast, which may cause a decrease in the thickness of the formed decarburized layer 200, as a result, the effect of improving the toughness of the manufactured hot stamping part may be minimal. Therefore, in the case where the line speed of the annealing furnace for annealing the base material 100 is in the range of about 30 meters per minute (mpm) to about 200 mpm, the productivity of the hot stamping part can be improved while improving the toughness of the manufactured hot stamping part.

[0100] In one embodiment, the annealing temperature of the base material 100 may be about 750° C. to about 900° C. In the case where the annealing temperature of the base material 100 is lower than about 750° C., the desired structure may not be obtained, and recrystallization may not be sufficiently completed. On the contrary, in the case where the annealing temperature of the base material 100 is higher than about 900° C., the annealing temperature may be too high, and the efficiency of the manufacturing process may be reduced. Therefore, in the case where the annealing temperature of the base material 100 is within the range of about 750° C. to about 900° C., the desired structure may be obtained, recrystallization may be sufficiently completed, and the efficiency of the manufacturing process may be improved.

[0101] The plating operation S500 may be an operation of forming a plating layer on the annealed base material 100. In one embodiment, the plating layer 300 may be formed on the annealed base material 100 by the plating operation S500. In detail, the plating layer 300 may be formed on the decarburized layer 200 by the plating operation S500. Here, the plating layer 300 may include a zinc (Zn)-based plating layer or an aluminum (Al)-based plating layer.

[0102] In detail, in the plating operation S500, the annealed base material 100 may be immersed in a plating bath. At this time, the plating bath may maintain a temperature of about 400° C. to about 700° C. The base material 100 (or the decarburized layer 200) may be coated with a coating of about 40 g / m 2 About 200g / m 2 Plating is performed to form a plated layer.

[0103] In one embodiment, the thickness t4 of the plating layer 300 formed on the base material 100 or the decarburized layer 200 may be about 5 μm to about 30 μm. In the case where the thickness t4 of the plating layer 300 is about 5 μm or less, the sacrificial ability of the plating layer 300 may be insufficient, and in the case where the thickness t4 of the plating layer 300 is about 30 μm or more, the cost of forming the plating layer 300 may increase, resulting in reduced economic feasibility. Therefore, in the case where the thickness t4 of the plating layer 300 is in the range of about 5 μm to about 30 μm, corrosion of the base material 100 of the hot stamping part can be prevented or minimized.

[0104] In one embodiment, annealing operation S400 and plating operation S500 can be carried out on the same line.Therefore, the line speed carrying out plating operation S500 can be about 30mpm to about 200mpm.When line speed is 30mpm or less, line speed may be too slow, causing productivity reduction.Control the plating amount by using air knife, and when line speed is 200mpm or more, because line speed is too fast, may be difficult to control the plating amount by using air knife.Therefore, when the line speed carrying out plating operation S500 is in the range of about 30mpm to about 200mpm, productivity can be improved, easily control the plating amount simultaneously.

[0105] In one embodiment, a plated steel sheet may be manufactured in which a plated layer 300 is formed over at least one surface of a base material 100 by a plating operation S500. Here, the plated steel sheet may include a base material 100, a decarburized layer 200 disposed on the base material 100, and a plated layer 300 disposed on the decarburized layer 200.

[0106] Figure 6 is a flow chart schematically illustrating a hot stamping operation according to an embodiment of the present invention, and Figure 7 is a flow chart schematically illustrating a heating operation according to an embodiment of the present invention.

[0107] Reference Figure 3 and Figure 6 , the hot stamping operation S600 may be performed after the plating operation S500. The hot stamping operation S600 may include a heating operation S610, a conveying operation S620, a forming operation S630, and a cooling operation S640.

[0108] First, a blank may be formed by cutting a plated steel sheet having the plated layer 300 formed over at least one surface of the base material 100. However, the present invention is not limited thereto.

[0109] In the heating operation S610, the blank may be heated in a heating furnace including a plurality of zones having different temperature ranges. Figure 7As shown, the heating operation S610 may include a multi-stage heating operation S611 and a soaking heating operation S612. The multi-stage heating operation S611 and the soaking heating operation S612 may be operations of heating the ingot while the ingot passes through a plurality of sections provided in the heating furnace.

[0110] In one embodiment, the overall temperature of the heating furnace may be about 680° C. to about 910° C. In detail, the overall temperature of the heating furnace performing the multi-stage heating operation S611 and the soaking heating operation S612 may be about 680° C. to about 910° C. Here, the temperature of the heating furnace performing the multi-stage heating operation S611 may be 680° C. to Ac3, and the temperature of the heating furnace performing the soaking heating operation S612 may be Ac3 to about 910° C.

[0111] In the multi-stage heating operation S611, the blank may be heated in stages (or the temperature may be increased) while passing through a plurality of sections provided in the heating furnace. Among the plurality of sections provided in the heating furnace, there may be a plurality of sections for performing the multi-stage heating operation S611, and the temperature is set for each section so that the temperature increases from the inlet of the heating furnace where the blank is supplied toward the outlet of the heating furnace where the blank is taken out, and thus the blank may be heated in stages (or the temperature may be increased).

[0112] The soaking heating operation S612 may be performed after the multi-stage heating operation S611. In the soaking heating operation S612, the multi-stage heated blank may be heated (or soaking heated) while passing through a section of the heating furnace set to a temperature of Ac3 to about 910° C. Among the plurality of sections provided in the heating furnace, there may be at least one section in which the soaking heating operation S612 is performed.

[0113] Figure 8 is a diagram of a heating furnace including a plurality of zones for describing a heating operation of a method for manufacturing a hot stamping part according to an embodiment of the present invention.

[0114] Reference Figure 8 , a heating furnace according to an embodiment may include a plurality of sections with different temperature ranges. In detail, the heating furnace may include a first section P1 with a first temperature range T1, a second section P2 with a second temperature range T2, a third section P3 with a third temperature range T3, a fourth section P4 with a fourth temperature range T4, a fifth section P5 with a fifth temperature range T5, a sixth section P6 with a sixth temperature range T6, and a seventh section P7 with a seventh temperature range T7.

[0115] In one embodiment, in the multi-stage heating operation S611, the blank may be heated in stages while passing through the first section P1 to the fourth section P4 defined in the heating furnace. In addition, in the uniform heating operation S612, the blank that has been multi-stage heated through the first section P1 to the fourth section P4 may be uniformly heated while passing through the fifth section P5 to the seventh section P7.

[0116] The first section P1 to the seventh section P7 may be sequentially arranged in the heating furnace. The first section P1 having the first temperature range T1 may be adjacent to the entrance of the heating furnace where the blank is supplied, and the seventh section P7 having the seventh temperature range T7 may be adjacent to the exit of the heating furnace where the blank is taken out. Therefore, the first section P1 having the first temperature range T may be the first section of the furnace, and the seventh section P7 having the seventh temperature range T7 may be the last section of the furnace.

[0117] The temperatures of the plurality of sections provided in the heating furnace (e.g., the temperatures of the first section P1 to the seventh section P7) may be increased from the inlet of the heating furnace where the blank is supplied toward the outlet of the heating furnace where the blank is taken out. However, the fifth section P5, the sixth section P6, and the seventh section P7 may have the same temperature. In addition, the temperature difference between two adjacent sections among the plurality of sections provided in the heating furnace may be greater than 0°C but less than or equal to about 100°C. For example, the temperature difference between the first section P1 and the second section P2 may be greater than 0°C but less than or equal to about 100°C.

[0118] The temperature of the heating furnace in the soaking heating operation S612 may be Ac3 to about 910°C. In the case where the temperature of the heating furnace in the soaking heating operation S612 is Ac3 or lower, the manufactured hot stamping component may not have the desired material quality. On the contrary, in the case where the temperature of the heating furnace in the soaking heating operation S612 is about 910°C or higher, zinc (Zn) contained in the plating layer 300 may evaporate, resulting in the loss of the plating layer 300. Therefore, in the case where the temperature of the heating furnace in the soaking heating operation S612 is in the range of Ac3 to about 910°C, the manufactured hot stamping component can be formed to have the desired material quality while preventing or minimizing the loss of the plating layer 300.

[0119] Figure 8 It is shown that the heating furnace according to one embodiment includes seven zones having different temperature ranges, but the present invention is not limited thereto. The heating furnace may include five, six or eight zones having different temperature ranges.

[0120] In one embodiment, since the heating operation S610 includes the multi-stage heating operation S611 and the soaking heating operation S612, the temperature of the heating furnace can be set in stages, and thus the energy efficiency of the heating furnace can be improved.

[0121] In one embodiment, the heating furnace may have a length of about 20m to about 40m along the conveying path of the blank. The heating furnace may include a plurality of sections with different temperature ranges, and the ratio of the length of the section where the blank is heated in multiple stages to the length of the section where the blank is heated evenly in multiple sections may be in the range of about 1:1 to about 4:1. In the case where the length of the section where the blank is heated evenly in the heating furnace is increased so that the ratio of the length of the section where the blank is heated evenly to the length of the section where the blank is heated evenly is greater than about 1:1, the amount of hydrogen infiltrated into the blank in the evenly heated section increases, which may increase delayed fracture. On the contrary, in the case where the length of the section where the blank is heated evenly is reduced so that the ratio of the length of the section where the blank is heated evenly to the length of the section where the blank is heated evenly is less than about 4:1, the evenly heated section (or time) cannot be fully ensured, and therefore, the strength of the hot stamping part manufactured by the manufacturing method of the hot stamping part may be uneven. For example, the length of the uniform heating zone among the plurality of zones provided in the heating furnace may be about 20% to about 50% of the total length of the heating furnace.

[0122] In one embodiment, the total heating time for performing the heating operation S610 may be from about 2 min to about 20 min. That is, the total time that the blank remains in the heating furnace may be from about 2 minutes to about 20 minutes. In the case where the total heating time for performing the heating operation S610 is less than about 2 min, the hot stamping parts manufactured may not have the desired material quality due to insufficient heating time. On the contrary, in the case where the total heating time for performing the heating operation S610 is about 20 min or longer, the heating time may be too long, which may reduce productivity and thus reduce economic feasibility. Therefore, in the case where the total heating time for performing the heating operation S610 is in the range of about 2 min to about 20 min minutes, the hot stamping parts manufactured may have the desired material quality while preventing or minimizing the deterioration of the economic feasibility of the manufacturing process.

[0123] After the heating operation S610 , a conveying operation S620 , a molding operation S630 , and a cooling operation S640 may be further performed.

[0124] In one embodiment, the conveying operation S620 may be an operation of conveying the heated blank from the heating furnace to the mold. Here, in the conveying operation S620, the heated blank may be cooled at ambient temperature (or room temperature). That is, the heated blank may be air-cooled during conveying. When the heated blank is not air-cooled, the mold inlet temperature (e.g., the molding start temperature) may increase, which may cause wrinkles (or bends) to appear on the surface of the manufactured hot stamping part. In addition, it may be necessary to air-cool the heated blank during conveying because the use of a refrigerant may affect subsequent processes (hot stamping).

[0125] In one embodiment, the forming operation S630 may be an operation of forming a molded body by hot stamping the conveyed blank. In detail, in the forming operation S630, the molded body may be formed by pressing the blank using a mold.

[0126] In one embodiment, the molding start temperature may be from about 500°C to about 700°C. When the molding start temperature is lower than 500°C, the molding start temperature may be too low, which may result in reduced formability of the blank, and the manufactured hot stamping parts may not have the desired structure and physical properties. On the contrary, when the molding start temperature is higher than about 700°C, wrinkles (or bends) may appear on the surface of the manufactured hot stamping parts. In addition, the coating may be sintered in the mold. Therefore, when the molding start temperature is about 500°C or to about 700°C, the formability of the blank can be improved, the manufactured hot stamping parts can have the desired structure and physical properties, and wrinkles (or bends) on the surface of the manufactured hot stamping parts can be prevented or minimized.

[0127] In one embodiment, the cooling operation S640 may be an operation of cooling the formed molded body. The cooling operation S640 may be performed in a mold that has pressed the blank.

[0128] In detail, the final product can be formed by simultaneously molding the blank into the final part shape and cooling the molded body in the mold. The mold may be provided with a cooling channel through which a refrigerant circulates. The molded body may be rapidly cooled by the circulation of the refrigerant supplied by the cooling channel provided in the mold. Here, in order to prevent the springback phenomenon of the plate material and maintain the desired shape, rapid cooling may be performed with the mold closed while applying pressure. When the molded body is formed and cooled, the average cooling rate may be set to at least about 10°C / s to the martensite final temperature.

[0129] In one embodiment, the cooling end temperature at which the cooling operation S640 is terminated may be about room temperature to about 200°C. In the case where the cooling end temperature is lower than room temperature, the productivity of the manufacturing process may be reduced. On the contrary, in the case where the cooling end temperature is higher than about 200°C, when the manufactured hot stamping part is air-cooled at room temperature, the hot stamping part may be deformed, and it may be difficult to achieve the desired material quality. Therefore, in the case where the cooling end temperature at which the cooling operation S640 is terminated is in the range of about room temperature to about 200°C, the productivity of the manufacturing method can be improved, and the deformation of the manufactured hot stamping part can be prevented or minimized.

[0130] In order to ensure the vibration damping performance of the hot stamping parts, the hot stamping parts need to have a certain level or higher (or a preset level or higher) of toughness. Here, the toughness of the hot stamping parts can be improved by adding alloying elements, but the addition of alloying elements may increase the manufacturing cost of the hot stamping parts, resulting in a decrease in economic feasibility. Therefore, it is necessary to control the process conditions for manufacturing the hot stamping parts so that the hot stamping parts have a certain level or higher (or a preset level or higher) of toughness. However, even when using various types of materials, process conditions may be required to manufacture hot stamping parts with a certain level or higher (or a preset level or higher) of toughness.

[0131] Therefore, the inventors of the present invention have obtained Relationship 2 through excessive repeated experiments, and the Relationship 2 allows the manufactured hot stamping part to have a VDA bending angle of about 60° or more. In one embodiment, the method for manufacturing a hot stamping part may satisfy the following Relationship 2. In detail, the temperature a in the soaking heating operation of the method for manufacturing a hot stamping part n and the total heating time b in the heating operation n The following relationship 2 can be satisfied.

[0132] <Relation 2>

[0133] 62≤91.81+K-0.022×a n -0.23×b n

[0134] In equation 2, K represents the material correction factor. Here, the material correction factor K is 0.71×c n -0.025×d n , and in the material correction factor K, c n Indicates the dew point of the annealing furnace of the base material, d n Indicates the linear speed of the annealing furnace for the base material.

[0135] In equation 2, a ncan represent the temperature during the soaking heating operation, the unit of the temperature during the soaking heating operation can be °C, and a n The value of may represent the value of the temperature in °C during the soaking heating operation. For example, when the temperature during the soaking heating operation is 900 °C, a n The value can be 900.

[0136] In equation 2, b n may represent the total heating time in a heating operation (for example, the total heating time in an operation of heating a blank), the unit of the total heating time in the heating operation may be minutes (min), and b n It can represent the value of the total heating time in minutes in the heating operation. For example, if the total heating time in the heating operation is 5 minutes, b n The value of can be 5.

[0137] As described above, in equation 2, K may represent a material correction coefficient. Here, the material correction coefficient K may be 0.71×c n -0.025×d n In the material correction factor K, c n It can represent the dew point of the annealing furnace of the base material. The dew point of the annealing furnace of the base material can be expressed in units of °C, and c n It can represent the value of the dew point of the annealing furnace of the base material in ° C. For example, when the dew point of the annealing furnace of the base material is +10 ° C, c n The value of can be 10. In addition, in the material correction factor K, d n It can represent the linear speed of the annealing furnace of the base material, and the unit of the linear speed of the annealing furnace of the base material can be meter per minute (mpm), and d n It can represent the value of the linear speed of the annealing furnace of the substrate material in mpm. For example, when the linear speed of the annealing furnace of the substrate material is 100 mpm, d n The value can be 100.

[0138] In one embodiment, the temperature a during the soaking heating operation is n and the total heating time b in the heating operation n The above relationship 2 can be satisfied. Here, since the material correction coefficient K is determined by the dew point c of the annealing furnace of the base material, n and the linear speed d of the annealing furnace of the base material n The coefficient of the uniform heating operation can also be said to be the temperature a n , total heating time in the heating step b n 、Dew point of annealing furnace for base material c n and the linear speed d of the annealing furnace of the base material nThe above relationship 2 is satisfied.

[0139] Here, the temperature a in the soaking heating operation n The total heating time b in the heating operation may be from about Ac3 to about 910°C. n The dew point c of the annealing furnace of the base material may be about 2 min to about 20 min. n The temperature may be between -15°C and +15°C, and the linear speed d n It may be from about 30 mpm to about 200 mpm.

[0140] Temperature a during the soaking heating operation n and the total heating time b in the heating operation n When the above relational expression 2 is satisfied, the toughness of the hot stamping part 1 manufactured by the method for manufacturing a hot stamping part can be improved. n and the total heating time b in the heating operation n When the above relationship 2 is satisfied, the hot stamping part 1 manufactured by the method for manufacturing a hot stamping part may have a VDA bending angle of about 60° or more. In addition, the hot stamping part 1 manufactured by the method for manufacturing a hot stamping part may have a tensile strength (TS) of about 1680 MPa to about 2000 MPa, a yield strength (YP) of about 1150 MPa to about 1500 MPa, and an elongation (EL) of about 4% to about 10%.

[0141] In other words, the temperature a in the soaking heating operation n , total heating time in heating operation b n 、Dew point of annealing furnace for base material c n and the linear speed d of the annealing furnace of the base material n When the above relational expression 2 is satisfied, the toughness of the hot stamping part 1 manufactured by the method for manufacturing a hot stamping part can be improved. n , total heating time in heating operation b n 、Dew point of annealing furnace for base material c n and the linear speed d of the annealing furnace of the base material n When the above relationship 2 is satisfied, the hot stamping part 1 manufactured by the method for manufacturing a hot stamping part may have a VDA bending angle of about 60° or more. In addition, the hot stamping part 1 manufactured by the method for manufacturing a hot stamping part may have a tensile strength (TS) of about 1680 MPa to about 2000 MPa, a yield strength (YP) of about 1150 MPa to about 1500 MPa, and an elongation (EL) of about 4% to about 10%.

[0142] Although the present invention has been described with reference to the embodiments shown in the accompanying drawings, they are merely exemplary, and those skilled in the art will appreciate that various changes and equivalent embodiments may be made therefrom. Therefore, the true technical protection scope of the present invention should be determined by the appended claims.

Claims

1. A method for manufacturing a hot stamping component, the method comprising: forming a blank by cutting a plated steel sheet having a plated layer formed on at least one surface of a base material; and heating the blank in a heating furnace comprising a plurality of zones having different temperature ranges, Wherein, the heating of the blank comprises: A multi-stage heating operation that heats the billet in stages; and The stepwise heated billet is subjected to a soaking heating operation of soaking heating at a temperature of Ac3 to 910°C, and Temperature a during soaking heating operation n The total heating time b in the heating of the blank n Satisfies the relationship: 62≤91.81+K-0.022×a n -0.23×b n , Where K is the material correction factor.

2. The method according to claim 1, wherein: The total heating time b in the heating of the blank n 2min to 20min.

3. The method according to claim 1, wherein: The material correction coefficient K is 0.71×c n -0.025×d n , Among them, c n Indicates the dew point of the annealing furnace of the base material, d n Indicates the linear speed of the annealing furnace for the base material.

4. The method according to claim 3, wherein: The dew point c of the annealing furnace of the base material n -15℃ to +15℃.

5. The method according to claim 3, wherein: The linear speed d of the annealing furnace of the base material n 30mpm to 200mpm.

6. The method according to claim 1, wherein: The annealing temperature of the base material is 750°C to 900°C.

7. The method according to claim 1, wherein: The annealing of the base material is performed in a gas atmosphere containing 0.5 volume % to 25 volume % hydrogen and the remainder nitrogen.

8. The method according to claim 1, wherein: A decarburized layer is further formed on the base material.

9. The method according to claim 8, wherein: The decarburized layer has a thickness of 10 μm to 100 μm.

10. The method according to claim 8, wherein: The average hardness of the decarburized layer is less than or equal to 80% of the average hardness of a point 1 / 4 away from the surface of the base material.

11. The method according to claim 1, wherein: The plating layer is a zinc (Zn)-based plating layer or an aluminum (Al)-based plating layer.

12. The method according to claim 1, wherein: The thickness of the coating is 5 μm to 30 μm.

13. The method according to claim 1, further comprising: After the blank is heated, conveying the heated blank; forming a molded body by pressing the transferred blank using a mold; as well as The resulting molded body is cooled.

14. A hot stamping component, comprising: Base material; a decarburized layer formed on the base material; as well as a coating formed on the decarburized layer, The hot stamping part has a tensile strength (TS) of 1680 MPa to 2000 MPa, a yield strength (YP) of 1150 MPa to 1500 MPa, and an elongation (EL) of 4% to 10%.

15. The hot stamped component according to claim 14, wherein: The average hardness of the decarburized layer is less than or equal to 70% of the average hardness of a point 1 / 4 away from the surface of the base material.

16. The hot stamped component according to claim 14, wherein: The content of carbon included in the plating layer is less than or equal to 50% of the content of carbon included in the base material.

17. The hot stamped component according to claim 14, wherein: The hot stamped part has a microstructure including a martensite fraction of 90% or more.

18. The hot stamped component according to claim 14, wherein: The decarburized layer has a thickness of 10 μm to 100 μm.

19. The hot stamped component according to claim 14, wherein: The thickness of the coating is 7 μm to 40 μm.

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