Component and method for manufacturing same

Abstract

The present invention relates to a member and a method for manufacturing the same, and more particularly, to a hot press molded member having excellent chemical conversion processability and a method for manufacturing the same.

Description

Technical Field

[0001] The present invention relates to a component and a manufacturing method thereof, and more particularly, to a hot press forming component having excellent chemical conversion treatment properties and a manufacturing method thereof. Background Art

[0002] In recent years, automobile manufacturers have been continuously researching vehicle lightweighting for improving fuel efficiency and CO2 emission regulations. Therefore, in order to increase the strength of steel under the same weight, various alloying elements are included, but problems such as increased hardenability and poor workability such as springback phenomenon occur.

[0003] To solve these problems, a hot press forming method has been proposed. The hot press forming method is a technique in which steel having a certain strength is processed in the austenite single phase region and then rapidly cooled to a low temperature, thereby forming a low temperature structure such as martensite in the steel and significantly increasing the strength of the product. By this method, when forming a component with high strength, the workability problem can be minimized.

[0004] In addition, in order to improve the corrosion resistance of the steel used in the hot press forming method, aluminizing is widely used. However, in terms of chemical conversion treatment properties, the main component of the plating bath is composed of aluminum, and it is difficult for phosphate crystals to grow. To improve this problem, various methods have been tried. Summary of the Invention

[0005] (I) Technical Problems to be Solved

[0006] An object according to an embodiment of the present invention is to provide a component and a manufacturing method thereof.

[0007] An object according to an embodiment of the present invention is to provide a hot press forming component having excellent chemical conversion treatment properties and a manufacturing method thereof.

[0008] The technical problems of the present invention are not limited to the above. Those of ordinary skill in the art can easily understand additional technical problems of the present invention from the overall content of this specification.

[0009] (II) Technical Solutions

[0010] According to an embodiment of the present invention, a component can be provided, the component including: a base steel plate; and a plating layer formed on the base steel plate, wherein the plating layer includes a first alloy layer, a second alloy layer, a third alloy layer, and a fourth alloy layer formed in sequence from the base steel plate, and the R value defined in the following relational expression 1 of the fourth alloy layer is 1200 to 4500.

[0011] R = [Rpc] [Zn]

[0012] (In the formula, [Rpc] is the surface roughness expressed as the number of peaks per 10 mm, and [Zn] is the weight % of the element.)

[0013] The base steel plate may contain, in weight %, C: 0.02-0.6%, Si: 0.001-2%, Al: 0.001-1%, Mn: 0.1-4%, P: 0.05% or less, S: 0.02% or less, N: 0.02% or less, B: 0.0001-0.01%, and the balance Fe and unavoidable impurities.

[0014] The base steel plate may further contain, in weight %, one or more selected from the group consisting of Ti: 0.1% or less, Cu: 1.00% or less, Mo: 1.00% or less, Cr: 1.00% or less, Ni: 1.00% or less, V: 1.00% or less, Ca: 0.01% or less, Nb: 0.1% or less, Sn: 1% or less, W: 1% or less, Sb: 1% or less, Mg: 0.1% or less, Co: 1% or less, As: 1% or less, Zr: 1% or less, Bi: 1% or less, and REM: 0.3% or less.

[0015] In terms of weight %, the Zn content of the fourth alloy layer may be 12.0-40.0%.

[0016] The Rpc of the fourth alloy layer may be 80.0 to 130.0.

[0017] In weight %, the first alloy layer may contain: Al: 5.0-18.0%, Si: 1.0-10.0%, Fe: 75.0-90.0%, Zn: 2.0% or less; in weight %, the second alloy layer may contain: Al: 25.0-48.0%, Si: 1.0-7.0%, Fe: 36.0-53.0%, Zn: 6.0-20.0%; in weight %, the third alloy layer may contain: Al: 18.0-43.0%, Si: 8.0-15.0%, Fe: 47.0-68.0%, Zn: 2.0% or less; in weight %, the fourth alloy layer may contain: O: 6.0% or less, Al: 36.0-73.0%, Si: 10.0% or less, Fe: 42.0% or less, Zn: 12.0-40.0%.

[0018] The coverage of the component after chemical conversion treatment may be greater than 50%.

[0019] According to an embodiment of the present invention, a manufacturing method of a component can be provided. The manufacturing method includes the following steps: preparing a base steel plate; immersing the base steel plate in a plating bath for plating. By weight percentage, the plating bath contains: Zn: 26.0 - 30.0%, Si: 6.0 - 9.0%, the balance being Al and inevitable impurities; performing skin pass rolling on the plated steel plate; heating the steel plate after the skin pass rolling to a temperature range of Ac3 to 950 °C and holding for 1 - 1000 seconds; and performing hot press forming on the steel plate after the heating and holding.

[0020] Before the plating step, an annealing step of heating the base steel plate to a temperature range of 600 - 950 °C and holding for 100 - 500 seconds in a gas atmosphere containing more than 70% of H2 and the balance being N2 at a dew point temperature of 5 - 20 °C can be further included.

[0021] The temperature of the plating bath can be 580 - 680 °C.

[0022] The skin pass rolling step can be performed with a reduction of 200 - 900 tons.

[0023] (III) Beneficial effects

[0024] According to an embodiment of the present invention, a component and its manufacturing method can be provided.

[0025] According to an embodiment of the present invention, a hot press formed component having excellent chemical conversion treatability and its manufacturing method can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic cross-sectional view of the plating layer of a component according to an embodiment of the present invention is shown.

[0027] Figure 2 It is a photograph obtained by measuring Invention Example 1 of an embodiment of the present invention by a glow discharge optical emission spectrometer (GDS) analysis method. DETAILED DESCRIPTION OF THE INVENTION

[0028] The following describes preferred specific embodiments of the present invention. The specific embodiments of the present invention can be modified into various forms, and the scope of the present invention should not be construed as being limited to the specific embodiments described below. These specific embodiments are provided to more specifically explain the present invention to those of ordinary skill in the technical field to which the present invention pertains.

[0029] Hereinafter, the present invention will be described in detail.

[0030] Components according to an embodiment of the present invention may include: a base steel plate; a coating layer formed on the base steel plate.

[0031] Base steel plate

[0032] The alloy composition of the base steel plate according to an embodiment of the present invention is not particularly limited. However, according to an embodiment of the present invention, by weight%, the base steel plate may contain C: 0.02 - 0.6%, Si: 0.001 - 2%, Al: 0.001 - 1%, Mn: 0.1 - 4%, P: 0.05% or less, S: 0.02% or less, N: 0.02% or less, B: 0.0001 - 0.01%, the balance being Fe and impurities.

[0033] The base steel plate of the present invention, in addition to the above composition, may contain the balance of iron (Fe) and inevitable impurities. Inevitable impurities may be inadvertently mixed in during the normal manufacturing process, so it is impossible to exclude these impurities. These impurities are well known to those skilled in the art of ordinary steelmaking manufacturing, so all of their contents are not particularly mentioned in this specification.

[0034] Furthermore, the base steel plate according to an embodiment of the present invention, by weight%, may optionally contain, as needed, one or more selected from Ti: 0.1% or less, Cu: 1.00% or less, Mo: 1.00% or less, Cr: 1.00% or less, Ni: 1.00% or less, V: 1.00% or less, Ca: 0.01% or less, Nb: 0.1% or less, Sn: 1% or less, W: 1% or less, Sb: 1% or less, Mg: 0.1% or less, Co: 1% or less, As: 1% or less, Zr: 1% or less, Bi: 1% or less, REM: 0.3% or less.

[0035] Coating layer

[0036] Components according to an embodiment of the present invention may include a coating layer formed on the base steel plate, and the coating layer may include a first alloy layer, a second alloy layer, a third alloy layer, and a fourth alloy layer formed sequentially from the base steel plate.

[0037] Figure 1 A schematic cross-sectional view of the coating layer of the component according to an embodiment of the present invention is shown. As Figure 1As shown, the coating layer of the present invention can be divided into 4 mutually distinct layers according to the diffusion gradient of the composition of the coating layer and the Fe, Al, Si, and Zn components of the base steel plate. In particular, for the alloy layer, when observing the cross-section of the coating layer in the backscattered electron (BSE) mode, each layer can be distinguished according to the weight of each alloy element. In particular, in the case of the third alloy layer, due to the high Si content, it is easy to distinguish the color from the second alloy layer and the fourth alloy layer according to the alloy element content.

[0038] According to an embodiment of the present invention, the coating layer can be divided into 4 alloy layers formed successively from the base steel plate, and may include: an α-Fe layer formed on the base steel plate; a first Fe-Al layer formed on the α-Fe layer; an Al-Fe-Si layer formed on the first Fe-Al layer; and a second Fe-Al layer formed on the Fe-Al-Si layer.

[0039] According to an embodiment of the present invention, in terms of weight %, the α-Fe layer as the first alloy layer may contain: Al: 5.0 - 18.0%, Si: 1.0 - 10.0%, Fe: 75.0 - 90.0%, Zn: below 2.0%. In terms of weight %, the first Fe-Al layer as the second alloy layer may contain: Al: 25.0 - 48.0%, Si: 1.0 - 7.0%, Fe: 36.0 - 53.0%, Zn: 6.0 - 20.0%. In terms of weight %, the Al-Fe-Si layer as the third alloy layer may contain: Al: 18.0 - 43.0%, Si: 8.0 - 15.0%, Fe: 47.0 - 68.0%, Zn: below 2.0%. According to an embodiment of the present invention, in terms of weight %, the second Fe-Al layer as the fourth alloy layer may contain: O: below 6.0%, Al: 36.0 - 73.0%, Si: below 10.0%, Fe: below 42.0%, Zn: 12.0 - 40.0%.

[0040] Fourth alloy layer

[0041] The R value defined in the following relational expression 1 of the fourth alloy layer may be 1200 to 4500.

[0042] [Relational expression 1]

[0043] R = [Rpc] [Zn]

[0044] (In the formula, [Rpc] is the surface roughness representing the number of peaks per 10 mm, and [Zn] is the weight % of the element.)

[0045] The influence of the chemical conversion treatment on the component is determined by the fourth alloy layer (the second Fe-Al layer) as the outermost layer. Therefore, in the present invention, the composition and surface roughness of this layer can be controlled. In the present invention, the composition of this layer is confirmed by cross-sectional SEM analysis. In addition, the surface roughness (Rpc, number of peaks per 10 mm) is measured according to ISO 4287:1997.

[0046] The product of the surface roughness and the Zn content mainly depends on the composition of the coating. In the present invention, their product is restricted. When the R value defined in the relational expression 1 is less than 1200, the Zn content is low, the phosphate treatment property is reduced or the number of peaks is low, and there may be a problem of poor painting adhesion. According to an embodiment of the invention, the R value can be 1500 or more. On the other hand, when the R value exceeds 4500, the Zn content of the entire coating increases, resulting in the occurrence of the LME (liquid-phase brittle fracture) phenomenon during welding, or the number of peaks of the roughness increases, and there may be a problem of deterioration of equipment such as molds or annealing furnaces due to friction, wear, etc. In addition, when manufacturing components by hot press forming, there is a possibility of generating cracks. According to an embodiment of the present invention, the R value can be 4100 or less.

[0047] In addition, the surface roughness (Rpc) of the component manufactured by hot forming is greatly affected by the coating composition regardless of the surface roughness before hot forming. When the roughness is large, the friction coefficient at high temperature becomes large, and due to friction, wear, etc., equipment such as molds or annealing furnaces may be deteriorated. Therefore, according to an embodiment of the present invention, the surface roughness can be 130.0 or less. According to an embodiment of the present invention, the surface roughness can be 120.0 or less. In addition, different from cold forming, since forming and processing are carried out by contact between metals or oxides without lubricating oil, a specified level of friction is required. In the present invention, the surface roughness can be 80.0 or more.

[0048] In addition, in the present invention, in order to ensure the desired chemical conversion treatment property, the Zn content of the fourth alloy layer can be 12.0% or more. As an embodiment of the present invention, the Zn content can be 14.0% or more. According to an embodiment of the present invention, the Zn content can be 40.0% or less. According to an embodiment of the present invention, the Zn content can be 38% or less.

[0049] According to an embodiment of the present invention, the coverage rate of the component after chemical conversion treatment is 50% or more, and excellent chemical conversion treatment characteristics can be obtained.

[0050] Hereinafter, the manufacturing method of the component of the present invention will be described in detail.

[0051] The component according to an embodiment of the present invention can be manufactured by preparing a base steel plate that meets the alloy composition of the present invention, plating, skin pass rolling, heating, and hot press forming.

[0052] Preparing the base steel plate

[0053] A base steel plate that meets the alloy composition of an embodiment of the present invention can be prepared. For the base steel plate according to an embodiment of the present invention, although its alloy composition is not particularly limited, it preferably meets the composition proposed in the present invention. The above description can be equally applied to the composition of the base steel plate.

[0054] Plating

[0055] The base steel plate can be immersed in a plating bath for plating. The plating bath contains, by weight%, Zn: 26.0 - 30.0%, Si: 6.0 - 9.0%, the balance being Al and inevitable impurities.

[0056] In the present invention, in order to control the surface roughness and Zn content of the coating, the composition of the plating bath can be controlled during plating.

[0057] In the coating, Zn forms an Al-Zn phase, thereby ensuring sacrificial corrosion resistance. In addition, the surface roughness after hot forming may be greatly affected by the coating composition independently of the surface roughness before hot forming. As the Zn content increases, the heat treatment time increases, and the roughness tends to increase. It can be inferred that this is because the thermal expansion coefficient (×10 -6 m / (m·°C)) value (30 to 35) of Zn is higher than that of Al (21 to 24). Therefore, when the same amount of heat is applied to the coating, as the Zn content increases, the displacement also increases, which results in an increase in roughness. To ensure this effect, the Zn content contained in the plating bath in the present invention can be 26.0 - 30.0%. When the Zn content in the plating bath is less than 26.0%, the Zn content in the fourth alloy layer may not reach the desired level, and as a result, there is a possibility of reducing the sacrificial corrosion resistance. According to an embodiment of the present invention, the Zn content can be limited to 26.5% or more. On the other hand, when the Zn content in the plating bath exceeds 30.0%, there is a possibility of exceeding the Zn content range of the coating, and as a result, there may be a problem of generating microcracks caused by LME. In addition, during hot press forming, there is also a possibility of generating cracks. As an embodiment of the present invention, it can contain 29.5% or less of Zn.

[0058] In addition, during manufacturing, in order to suppress the diffusion of Al into the base steel plate, the Si content of the plating bath can be limited to 6.0 - 9.0%. The Si content of the plating bath affects the Si solid solution phase, so the weight% value may be a smaller value compared to the target Si content of the coating. When the Si content is less than 6.0%, the temperature of the molten metal is relatively high, and the thickness of the FeAl3 and Fe2Al5 intermetallic compounds is too thick, which may cause problems such as brittle materials. According to an embodiment of the present invention, the Si content can be limited to 6.5% or more. On the other hand, when the Si content exceeds 9.0%, the effect of reducing the thickness of the intermetallic compound brought by adding Si may be reduced, and there may be a problem of Si precipitation. According to an embodiment of the present invention, Si can be included at 8.5% or less.

[0059] According to an embodiment of the present invention, the temperature of the plating bath can be 580 - 680°C.

[0060] In addition, according to an embodiment of the present invention, before the plating step, a step of annealing the base steel plate can be further included. As an embodiment of the present invention, a further annealing step can be carried out in which the base steel plate is heated to a temperature range of 600 - 950°C and held for 100 - 500 seconds in a gas atmosphere containing 70% or more of H2 and the remainder being N2 at a dew point temperature of 5 - 20°C.

[0061] Skin Pass Mill

[0062] The plated steel plate can be subjected to Skin Pass Mill (SPM).

[0063] In this process, by rolling with a specified elongation load or reduction amount, roughness for improving the stamping formability of the steel plate can be imparted, and surface defects can be removed.

[0064] In the present invention, during rolling, a reduction amount of 200 - 900 tons can be applied. When the reduction amount is less than 200 tons, defects such as flow mark shapes and scratches can be observed on the surface. On the other hand, when a reduction amount of more than 900 tons is applied, the wear of the roll will be aggravated, which will affect the reduction of the productivity of the steel plate. The elongation rate of the steel plate increases by more than 1%, so it may affect the quality of the final product.

[0065] Generally, the transfer rate of the plated steel plate (Ra of the sheet / Ra of the roll) can be obtained by A HRB (Roll Hardness) + B It is calculated by the reduction ratio, which is at the level of 30 - 70%. Among them, A and B are constants and can be determined according to the material, diameter of the roll, and equipment scale. At this time, the roughness (Ra) of the roll can be 1.5 - 3.0 μm. When the roughness of the roll is less than 1.5 μm, the surface is smooth, which may reduce the workability. On the other hand, when the roughness of the roll exceeds 3.0 μm, stress concentrates on the high peaks of the fine unevenness of the roll, resulting in rapid wear, so the durability life may be shortened.

[0066] Heating and holding

[0067] The steel plate after the skin pass rolling can be heated to a temperature range of Ac3 to 950 °C and held for 1 - 1000 seconds.

[0068] Before performing the heating step, a step of processing the steel plate into appropriate dimensions and shapes can be carried out first.

[0069] During heating, when the temperature is lower than the Ac3 temperature, there may be a problem that the material is difficult to completely transform into a single-phase austenite. When the temperature exceeds 950 °C, there may be problems such as surface oxidation or an increase in the hydrogen content in the steel.

[0070] When holding after heating, in order to reduce carbon emissions and ensure mechanical and physical properties, it is preferable to shorten the holding time as much as possible. When the holding time is too long, in order to reduce carbon emissions and inhibit the excessive diffusion of Fe in the coating, the upper limit of the holding time can be limited to 1000 seconds.

[0071] [Formula]

[0072] Ac3 = -230.5[C] + 31.6[Si] - 20.4[Mn] - 39.8[Cu] - 18.1[Ni] - 14.8[Cr] + 16.8[Mo] + 912

[0073] (In the formula, [C], [Si], [Mn], [Cu], [Ni], [Cr], and [Mo] are the weight percentages of each element.)

[0074] Hot press forming

[0075] The steel plate after the heating and holding can be hot press formed.

[0076] In the present invention, the heated steel plate can be hot formed to form a desired shape. In the present invention, hot press forming can be carried out using a mold, and the conditions of this process are not particularly limited. The hot press forming conditions commonly used in the same technical field can be applied. Detailed implementation mode

[0077] Hereinafter, the present invention will be described more specifically by way of examples. However, it should be noted that the following examples are only used to illustrate the present invention for more detailed description and do not limit the scope of the rights of the present invention.

[0078] (Example)

[0079] Prepare a base steel plate which, by weight %, contains C: 0.22%, Si: 0.28%, Al: 0.036%, Mn: 1.2%, P: 0.009%, S: 0.0006%, N: 0.0039%, B: 0.0031%, Ti: 0.03%, Cr: 0.21%, and the balance Fe. Then, plating and leveling rolling are carried out under the conditions shown in Table 1 below to manufacture a plated steel plate. After that, the manufactured plated steel plate is cut into a size of 380×400 mm 2 and then heated and hot-pressed to form a component. During plating, plating is carried out according to the plating bath compositions shown in Table 1. The plating bath compositions contain inevitable impurities in addition to the disclosed Zn, Si, and Al.

[0080] [Table 1]

[0081]

[0082] The coating characteristics and physical properties of the manufactured components are observed and shown in Table 2 below.

[0083] First, the coating is observed using a scanning electron microscope (SEM). Specifically, the cross-section of the hot-formed sample is fixed, and each layer can be observed at a magnification of ×2000 in the backscattered electron (BSE) mode. The center points of each phase are measured three times at different positions using an energy dispersive X-ray spectroscopy (EDS), and then the composition of the coating is represented by the three-point average value.

[0084] In addition, the influence of the chemical conversion treatment is determined by the fourth alloy layer (the second Fe-Al layer) as the outermost layer. Therefore, the composition of this layer is confirmed by cross-section SEM analysis. In addition, the surface roughness (Rpc, number of peaks per 10 mm) is measured according to ISO 4287:1997.

[0085] In addition, the manufactured test pieces are subjected to chemical conversion treatment in the order of degreasing - water washing 1 - surface conditioning - phosphate treatment - water washing 2. The test pieces subjected to the chemical conversion treatment are observed at 150 times magnification using a scanning electron microscope, and the phosphate coverage area is calculated using an image analyzer software and shown in Table 3 below. The specific chemical conversion treatment conditions are as follows. When the phosphate coverage rate is 50% or more, it is recorded as O, and when it is less than 50%, it is recorded as X.

[0086] ○Chemical conversion treatment

[0087] - Degreasing: FC-4460A 20 g / L, FC-4460B 12 g / L (DAEHAN PARKERIZING Co., Ltd.), treatment time is 90 seconds, temperature is 60 °C

[0088] - Water washing 1: treatment time is 10 seconds, at room temperature

[0089] - Surface adjustment: PL-Z 5 g / L (DAEHAN PARKERIZING Co., Ltd.), concentration pH 7.5 to 11, treatment time is 21 seconds, at room temperature

[0090] - Phosphate treatment: PB-3111 28.2 g / L, NT-4055 5.8 g / L (DAEHAN PARKERIZING Co., Ltd.), FA (free acidity) / TA (total acidity) are 1.1 to 1.5 / 11.1 to 11.8 respectively, treatment time is 120 seconds, phosphate treatment solution temperature is 40 - 45 °C

[0091] - Water washing 2: treatment time is 10 seconds, at room temperature

[0092] [Table 2]

[0093]

[0094] [Table 3]

[0095]

[0096] As shown in Table 2 and Table 3, in the case of the inventive examples that meet the conditions of the present invention, the features proposed by the present invention can be met, and the physical properties expected by the present invention can also be ensured.

[0097] Figure 2 is a photograph measured by the glow discharge spectrometer (GDS) analysis method for Inventive Example 1 of an embodiment of the present invention. As Figure 1 shown, the alloy element content according to depth can be confirmed from the plating surface along the thickness direction of the base steel plate.

[0098] On the other hand, Comparative Examples 1 to 10 and Comparative Example 12 are cases where the plating bath composition or manufacturing conditions proposed by the present invention are deviated from, and it can be confirmed that the plating expected by the present invention cannot be manufactured, and the physical properties are also poor. In addition, in Comparative Examples 9 to 11, cracks occur during hot forming, so the product performance is poor.

[0099] The present invention has been described in detail above through embodiments, but other forms of embodiments are also allowed. Therefore, the technical idea and scope of the claims are not limited to the embodiments.

Claims

1. A component, comprising: A base steel plate; And A coating formed on the base steel plate, Wherein the coating includes a first alloy layer, a second alloy layer, a third alloy layer, and a fourth alloy layer sequentially formed from the base steel plate, The R value defined in the following relational expression 1 of the fourth alloy layer is 1200 to 4500, R = [Rpc] [Zn] In the formula, [Rpc] is the surface roughness representing the number of peaks per 10 mm, and [Zn] is the weight % of the element.

2. The component according to claim 1, wherein By weight %, the base steel plate contains: C: 0.02 - 0.6%, Si: 0.001 - 2%, Al: 0.001 - 1%, Mn: 0.1 - 4%, P: below 0.05%, S: below 0.02%, N: below 0.02%, B: 0.0001 - 0.01%, the balance of Fe and inevitable impurities.

3. The component according to claim 2, wherein, By weight %, the base steel plate further contains one or more selected from Ti: below 0.1%, Cu: below 1.00%, Mo: below 1.00%, Cr: below 1.00%, Ni: below 1.00%, V: below 1.00%, Ca: below 0.01%, Nb: below 0.1%, Sn: below 1%, W: below 1%, Sb: below 1%, Mg: below 0.1%, Co: below 1%, As: below 1%, Zr: below 1%, Bi: below 1%, REM: below 0.3%.

4. The component according to claim 1, wherein, By weight %, the Zn content of the fourth alloy layer is 12.0 - 40.0%.

5. The component according to claim 1, wherein The Rpc of the fourth alloy layer is 80.0 to 130.

0.

6. The component according to claim 1, wherein, By weight %, the first alloy layer contains: Al: 5.0 - 18.0%, Si: 1.0 - 10.0%, Fe: 75.0 - 90.0%, Zn: below 2.0%, by weight %, the second alloy layer contains: Al: 25.0 - 48.0%, Si: 1.0 - 7.0%, Fe: 36.0 - 53.0%, Zn: 6.0 - 20.0%, by weight %, the third alloy layer contains: Al: 18.0 - 43.0%, Si: 8.0 - 15.0%, Fe: 47.0 - 68.0%, Zn: below 2.0%, by weight %, the fourth alloy layer contains: O: below 6.0%, Al: 36.0 - 73.0%, Si: below 10.0%, Fe: below 42.0%, Zn: 12.0 - 40.0%.

7. The component according to claim 1, wherein The coverage rate of the component after chemical conversion treatment is 50% or more.

8. A method for manufacturing a component, comprising the following steps: Prepare a base steel plate; Immerse the base steel plate in a plating bath for plating. By weight %, the plating bath contains: Zn: 26.0 - 30.0%, Si: 6.0 - 9.0%, the balance of Al and inevitable impurities; Level - roll the plated steel plate; Heat the level - rolled steel plate to a temperature range of Ac3 to 950 °C and hold for 1 - 1000 seconds; and Hot - press - form the heated and held steel plate.

9. The manufacturing method of the component according to claim 8, wherein, Before the plating step, it further includes an annealing step of heating the base steel plate to a temperature range of 600 - 950 °C and holding for 100 - 500 seconds in a gas atmosphere containing more than 70% H2 and the rest N2 at a dew point temperature of 5 - 20 °C.

10. The method for manufacturing a component according to claim 8, wherein, The temperature of the plating bath is 580 - 680 °C.

11. The method for manufacturing the component according to claim 8, wherein, The temper rolling step is carried out with a reduction of 200 - 900 tons.

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