Zn-al-mg-based coated steel material and method of manufacturing same

Abstract

The present invention relates to a Zn-Al-Mg-based coated steel material and a method of manufacturing same. An aspect of the present invention is to provide a Zn-Al-Mg-based coated steel material and a method of manufacturing same.

Description

Zn-Al-Mg plated steel and method for manufacturing the same

[0001] The present invention relates to a Zn-Al-Mg-based plated steel material and a method for manufacturing the same.

[0002] Recently, the installation of solar power plants has been expanding in accordance with eco-friendly policies. There is a trend of these solar power plants shifting from land-based locations to harsh environments such as reclaimed land, abandoned salt fields, and deserts; in particular, as they move to saline environments like water, problems regarding vulnerability to corrosion are emerging.

[0003] Generally, structures such as square tubes are used for the installation of solar power plants, and galvanized steel sheets are mainly used as the material for these structures to ensure corrosion resistance.

[0004] However, galvanized steel sheets face a problem where they become locally more vulnerable to corrosion as the plating layer is lost during processes such as forming or welding.

[0005] Accordingly, there is a need for measures to prevent the deterioration of corrosiveness caused by the loss of the plating layer on galvanized steel sheets.

[0006] One aspect of the present invention is to provide a Zn-Al-Mg-based plated steel material and a method for manufacturing the same.

[0007] A preferred aspect of the present invention is to provide a Zn-Al-Mg-based plated steel material having excellent corrosion resistance and a method for manufacturing the same.

[0008] The problems of the present invention are not limited to those described above. A person skilled in the art to which the present invention pertains will have no difficulty understanding additional problems of the present invention from the overall contents of this specification.

[0009] One embodiment of the present invention provides a Zn-Al-Mg plated steel material having a Zn-Al-Mg plating layer formed on at least one surface of a substrate steel plate, wherein the Zn-Al-Mg plating layer has a void portion, and a thermal spray coating layer is formed within the void portion, and the thermal spray coating layer comprises a Zn thermal spray coating layer; and an Al thermal spray coating layer formed on the Zn thermal spray coating layer; wherein the thermal spray coating layer has an average thickness deviation of 70% or less, the area of ​​pore defects within the thermal spray coating layer is 9.5% or less, and the average thickness of the thermal spray coating layer is 30 to 100 μm.

[0010] The thickness ratio of the Zn thermal spray coating layer to the above thermal spray coating layer may be 30 to 70%.

[0011] The thickness ratio of the Al thermal spray coating layer to the above thermal spray coating layer may be 30 to 70%.

[0012] The above Zn-Al-Mg plated steel can have the shape of a steel pipe or a square pipe.

[0013] Another embodiment of the present invention provides a method for manufacturing a Zn-Al-Mg plated steel material, comprising the steps of: preparing a substrate steel plate having a Zn-Al-Mg plating layer formed on at least one surface; forming a loss portion in the Zn-Al-Mg plating layer; and performing a thermal spray coating so that a thermal spray coating layer is formed in the loss portion; wherein the step of performing the thermal spray coating includes the step of forming a Zn thermal spray coating layer; and the step of forming an Al thermal spray coating layer on the Zn thermal spray coating layer; and wherein, during the step of performing the thermal spray coating, the method satisfies the following [Equation 1].

[0014] [Relationship 1] 54 ≤(-66.3X+68Y+D 2 ) / 60+50 ≤ 76

[0015] (However, in the above [Equation 1], X represents the feed speed of the base steel plate, Y represents the spray speed of the thermal spray material, and D represents the spray distance.)

[0016] The step of forming the above-mentioned loss portion may include forming the base steel plate into the shape of a steel pipe, welding it, and then removing the weld bead.

[0017] During the above thermal spray coating step, the transfer speed (X) of the substrate steel plate may be 8 to 50 m / min.

[0018] During the above-mentioned thermal spray coating step, the spray speed (Y) of the thermal spray material may be 3 to 10 m / min.

[0019] In the above step of thermal spray coating, the spray distance (D) may be 35 to 45 mm.

[0020] After the above-mentioned thermal spray coating step, the method may additionally include a step of forming the base steel plate into the shape of a square tube.

[0021] According to one aspect of the present invention, a Zn-Al-Mg-based plated steel material and a method for manufacturing the same can be provided.

[0022] According to a preferred aspect of the present invention, a Zn-Al-Mg-based plated steel material having excellent corrosion resistance and a method for manufacturing the same can be provided.

[0023] FIG. 1 is a schematic diagram showing an embodiment of a Zn-Al-Mg plated steel material having a loss portion formed in the plating layer according to an embodiment of the present invention.

[0024] FIG. 2 is a schematic diagram showing an embodiment of a Zn-Al-Mg plated steel material having a Zn thermal spray coating layer and an Al thermal spray coating layer formed on the Zn thermal spray coating layer according to an embodiment of the present invention.

[0025] FIG. 3 is a schematic diagram illustrating a method for manufacturing a Zn-Al-Mg-based plated steel material according to one embodiment of the present invention.

[0026] Preferred embodiments of the present invention will be described below with reference to the attached drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0027] In addition, embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the relevant technical field.

[0028] In drawings, the shapes and sizes of elements may be exaggerated for clearer explanation.

[0029] In describing the embodiments of the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, such definitions should be based on the content throughout this specification. The terms used in the detailed description are merely for describing the embodiments of the present invention and should not be limited in any way. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form.

[0030] In this description, expressions such as “include” or “equipped” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts or combinations thereof other than those described.

[0031] In this specification, terms such as 'top', 'upper', 'upper surface', 'lower', 'lower surface', 'lower surface', and 'side surface' are based on the drawings and may actually vary depending on the direction in which the elements or components are arranged.

[0032] Additionally, throughout the specification, when it is said that one part is 'connected' to another part, this includes not only cases where they are 'directly connected,' but also cases where they are 'indirectly connected' with other elements in between.

[0033] The present invention will be described in detail below through each embodiment or example of the invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may also be combined with other embodiments or examples. Accordingly, the citation of claims in the patent claims is merely an example of an embodiment, and the technical concept of the present invention should not be interpreted as being limited only to a combination with the cited claims; rather, combinations with various claims are also included within the scope of the technical concept of the present invention.

[0034] FIG. 1 is a schematic diagram showing an embodiment of a Zn-Al-Mg plated steel material having a loss portion formed in a plating layer according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing an embodiment of a Zn-Al-Mg plated steel material having a Zn thermal spray coating layer and an Al thermal spray coating layer formed on the Zn thermal spray coating layer formed in the loss portion according to an embodiment of the present invention.

[0035] Hereinafter, a Zn-Al-Mg plated steel material according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2. As shown in FIG. 1, a Zn-Al-Mg plated steel material (1) according to an embodiment of the present invention has a Zn-Al-Mg plating layer (20) formed on at least one surface of a base steel plate (10), and the Zn-Al-Mg plating layer may have a void portion (22). The void portion (22) may be formed by removing the weld bead after welding the steel material. Generally, plated steel is advantageous for securing corrosion resistance, but if a void portion (22) is formed, the base steel plate is directly exposed to the usage environment, so the corrosion resistance is significantly reduced. Accordingly, in the present invention, corrosion resistance can be improved by forming a thermal spray coating layer (30) within the void portion (22). Meanwhile, the present invention does not specifically limit the type of the substrate steel sheet, and all substrate steel sheets for Zn-Al-Mg-based plated steel materials used in the relevant technical field may be used. Furthermore, the present invention does not specifically limit the type of the Zn-Al-Mg-based plating layer, and all Zn-Al-Mg-based plating layers used in the relevant technical field may be applied.

[0036] However, as an example, the Zn-Al-Mg plating layer may contain Mg: 0.50~8.0%, Al: 1.0~15.0%, the remainder being Zn and unavoidable impurities. Additionally, the Zn-Al-Mg plating layer may further include one or more of the following groups (a) to (h).

[0037] (a) At least one of Si: 0.5% or less, Ni: 0.5% or less

[0038] (b) At least one of the following: Ca: 1.0% or less, La: 0.1% or less, Ce: 0.1% or less, Y: 0.1% or less, Sr: 1.0% or less

[0039] (c) Ti: 0.1% or less

[0040] (d) W: 0.5% or less

[0041] (e) Cu: 2.0% or less

[0042] (f) At least one of Fe: 1.0% or less, Cr: 0.5% or less, Mn: 0.5% or less, V: 0.5% or less

[0043] (g) At least one of B: 0.1% or less, P: 0.1% or less

[0044] (h) At least one of Sn: 1.0% or less, Sb: 1.0% or less, Bi: 1.0% or less

[0045] The above thermal spray coating layer (30) may include a Zn thermal spray coating layer (32); and an Al thermal spray coating layer (34) formed on the Zn thermal spray coating layer.

[0046] The above thermal spray coating layer may have an average thickness deviation (F) of 70% or less. If the average thickness deviation of the above thermal spray coating layer exceeds 70%, the thickness of the coating layer may be non-uniform, which may reduce corrosion resistance. In the present invention, since a lower average thickness deviation of the above thermal spray coating layer is advantageous, the lower limit thereof is not specifically limited, and preferably, the lower limit thereof may be 0%. Meanwhile, the average thickness deviation of the above thermal spray coating layer can be calculated using Equation 1 below.

[0047] [Equation 1] Average thickness deviation of thermal spray coating layer / Average thickness of thermal spray coating layer × 100

[0048] The area (K) of pore defects within the thermal spray coating layer may be 9.5% or less. If the area of ​​pore defects within the thermal spray coating layer exceeds 9.5%, the pores may become a penetration path for corrosion-causing substances, thereby reducing corrosion resistance. Since the present invention is advantageous when the pore defects are smaller, the lower limit of the fraction of pore defects is not specifically limited, and as an example, the lower limit may be 0%. Meanwhile, the present invention does not specifically limit the size of the pores, but the pores may have a size of 5 to 40 μm in terms of original equivalent diameter.

[0049] The average thickness (T) of the above thermal spray coating layer may be 30 to 100 μm. If the average thickness of the above thermal spray coating layer is less than 30 μm, it may be difficult to ensure sufficient corrosion resistance, and if it exceeds 100 μm, it may be difficult to ensure uniformity of the thermal spray coating layer, which may actually reduce corrosion resistance.

[0050] The thickness ratio of the Zn thermal spray coating layer to the above thermal spray coating layer may be 30 to 70%, and the thickness ratio of the Al thermal spray coating layer to the above thermal spray coating layer may be 30 to 70%. By securing the Zn thermal spray coating layer and the Al thermal spray coating layer with appropriate thickness fractions in this way, corrosion resistance can be further improved.

[0051] The above Zn-Al-Mg plated steel can have the shape of a steel pipe or a square pipe.

[0052] As described above, the Zn-Al-Mg plated steel material according to one embodiment of the present invention can prevent corrosion resistance from being reduced due to the loss of the plating layer.

[0053] In the present invention, the method for manufacturing the Zn-Al-Mg-based plated steel material described above is not particularly limited, but a preferred example of the method for manufacturing the Zn-Al-Mg-based plated steel material is described below with reference to FIG. 3.

[0054] FIG. 3 is a schematic diagram illustrating a method for manufacturing a Zn-Al-Mg-based plated steel material according to one embodiment of the present invention.

[0055] First, a base steel plate (10) having a Zn-Al-Mg-based plating layer (20) formed on at least one surface is prepared. In the present invention, the preparation process is not specifically limited, and any plating process available in the relevant technical field can be used.

[0056] Subsequently, a loss portion (22) is formed in the Zn-Al-Mg-based plating layer. The step of forming the loss portion may include forming the base steel plate into the shape of a steel pipe, welding it, and then removing the weld bead (24). In the present invention, the welding method is not specifically limited and can be performed by a welding device (100). As an example, high-frequency resistance welding or high-frequency induction welding may be used. In addition, in the present invention, the welding bead removal method is not specifically limited and can be performed by a welding bead removal device (200).

[0057] Subsequently, a thermal spray coating is applied to form a thermal spray coating layer on the above-mentioned lost portion. In the present invention, the thermal spray coating method is not specifically limited and can be performed by a thermal spray coating device (300). However, as an example, the thermal spray coating may utilize flame spray coating or electro-arc spray coating, and more advantageously, flame spray coating may be used.

[0058] The above thermal spray coating step may include: a step of forming a Zn thermal spray coating layer (32); and a step of forming an Al thermal spray coating layer (34) on the Zn thermal spray coating layer. As an example, the step of forming the Zn thermal spray coating layer (32) may be performed by a first thermal spray coating device (300), and the step of forming the Al thermal spray coating layer (34) may be performed by a second thermal spray coating device (400).

[0059] During the above thermal spray coating step, the following [Equation 1] can be satisfied. The following [Equation 1] is an equation for more advantageously controlling pore defects within the thermal spray coating layer. If the value of the following [Equation 1] is less than 54, it may be difficult to secure corrosion resistance because sufficient density or appropriate thickness of the coating layer cannot be secured. If the value of the following [Equation 1] exceeds 76, there may be a disadvantage in that the thickness variation increases, accelerating local corrosion. The lower limit of the value of the following [Equation 1] is more advantageous at 55, more advantageous at 56, and most advantageous at 57. The upper limit of the value of the following [Equation 1] is more advantageous at 75, more advantageous at 74, and most advantageous at 73.

[0060] [Relationship 1] 54 ≤(-66.3X+68Y+D 2 ) / 60+50 ≤ 76

[0061] (However, in the above [Equation 1], X represents the feed speed of the base steel plate, Y represents the spray speed of the thermal spray material, and D represents the spray distance.)

[0062] During the above thermal spray coating step, the transfer speed (X) of the substrate steel plate may be 8 to 50 m / min. If the transfer speed of the substrate steel plate is less than 8 m / min, there may be a disadvantage in that an excessive and uneven thermal spray coating layer is formed, resulting in reduced corrosion resistance, and if it exceeds 50 m / min, there may be a disadvantage in that corrosion resistance is not secured due to the formation of an uneven and thin thermal spray coating layer.

[0063] During the above-mentioned thermal spray coating step, the spray speed (Y) of the thermal spray material may be 3 to 10 m / min. If the spray speed of the thermal spray material is less than 3 m / min, there may be a disadvantage in that corrosion resistance is not secured due to the formation of an uneven and thin thermal spray coating layer, and if it exceeds 10 m / min, there may be a disadvantage in that corrosion resistance is reduced due to the formation of an excessive and uneven thermal spray coating layer. The spray speed of the above-mentioned thermal spray material may be the respective spray speeds of the Zn and Al thermal spray materials. Meanwhile, the present invention does not specifically limit the form of the above-mentioned thermal spray material, and any form commonly used in the relevant technical field may be used. However, as an example, the above-mentioned thermal spray material may have the form of a wire or a powder.

[0064] During the above-mentioned thermal spray coating step, the spray distance (D) may be 35 to 45 mm. If the spray distance (D) is less than 35 mm, the spray volume may scatter, resulting in the formation of an uneven spray coating layer; if it exceeds 45 mm, a spray coating layer with low density may be formed, which may result in a disadvantage where the quality of the spray coating is not ensured. Meanwhile, the above-mentioned spray distance (D) may be the distance from the nozzle of the above-mentioned thermal spray coating device (300) to the surface of the Zn-Al-Mg-based plating layer.

[0065] After the above-mentioned thermal spray coating step, the method may additionally include a step of forming the base steel plate into the shape of a square tube. The present invention is not particularly limited to the forming process, and any method commonly used in the relevant technical field may be used.

[0066] The present invention will be described in detail below through examples. However, it should be noted that the examples described below are intended merely to illustrate and embody the present invention and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the patent claims and matters reasonably inferred therefrom.

[0067] (Example)

[0068] First, a substrate steel plate was prepared with a Zn-Al-Mg (Al: 12 wt%, Mg: 5 wt%, remainder Zn) plating layer formed on one side. Subsequently, the substrate steel plate was formed into the shape of a steel pipe and welded, and the weld bead was removed to form a void in the plating layer. Then, a thermal spray coating layer was formed using a flame spray coating method under the conditions listed in Table 1 below. At this time, a Zn thermal spray coating layer was formed, and then an Al thermal spray coating layer was formed on top of the Zn thermal spray coating layer. For the Zn-Al-Mg plated steel material manufactured in this manner, the average thickness deviation of the thermal spray coating layer, the average thickness of the thermal spray coating layer, the pore defect area within the thermal spray coating layer, the thickness ratio of the Zn and Al thermal spray coating layers, and corrosion resistance were measured, and the results are shown in Table 1 below.

[0069] The average thickness deviation of the thermal spray coating layer, the average thickness of the thermal spray coating layer, the pore defect area within the thermal spray coating layer, and the thickness ratio of the Zn and Al thermal spray coating layers were measured by observing the cross-section of the Zn-Al-Mg plated steel material manufactured above using an optical microscope at 100x magnification. At this time, the average thickness deviation of the thermal spray coating layer, the average thickness of the thermal spray coating layer, and the thickness ratio of the Zn and Al thermal spray coating layers were measured at 10 locations at equal intervals, and the average values ​​were calculated. The thickness ratio of the Zn and Al thermal spray coating layers was calculated from the measured average thickness of the Zn and Al thermal spray coating layers.

[0070] The average thickness deviation of the above Zn and Al thermal spray coating layers was calculated as the average value of the difference between the measured thickness of the Zn and Al thermal spray coating layers and the average thickness.

[0071] The pore defect area within the Zn and Al thermal spray coating layer was measured as the area fraction of pores having an equivalent diameter of 5 to 40 μm relative to the area of ​​the Zn and Al thermal spray coating layer.

[0072] Corrosion resistance was measured using the Cyclic Corrosion Test (CCT) evaluation method according to ISO 14993 standards. In this case, the evaluation of corrosion resistance can be based on the CCT red rust initiation time of 3,500 hours.

[0073] Classification Substrate Steel Plate Transfer Speed ​​(X) (m / min) Spray Material Spray Speed ​​(Y) (m / min) Spraying Distance (D) (mm) [Equation 1] Average Thickness of Spray Coating Layer (T) (㎛) Deviation in Average Thickness of Spray Coating Layer (F) (%) Zn Spray Coating Layer Thickness Ratio (P) (%) Al Spray Coating Layer Thickness Ratio (%) Coating Layer Pore Defect Area (K) (%) Corrosion Resistance (Time) Invention Example 1 100 3.240 69.260 373 862 0.65,300 Invention Example 2 100 4.64 375.076 105 149 1.64,900 Invention Example 3 100 6.03 667.48 3146 238 1.85,300 Invention Example 4 100 4.63 665.830 4238620.93,600 Invention Example 5104.64375.095452481.73,500 Invention Example 6204.64059.8426743573.63,800 Invention Example 7256.04055.8383655454.14,100 Invention Example 8154.64065.334653474.34,500 Comparative Example 15574023.84442633711.91,800 Comparative Example 2574079.11038561391.52,200 Comparative Example 3402.94035.8183442584.31,500 Comparative Example 440124046.11037265358.82,600 Comparative Example 54583024.33267623 89.81,600 Comparative Example 64585051.0108105584213.62,500 Comparative Example 7352.54040.8124826747.21,700 Comparative Example 8252.54051.9105659286.62,800 Comparative Example 95510.54027.8226748527.21,100 [Relationship 1] (-66.3X+68Y+D 2 ) / 60+50

[0074] As can be seen from Table 1 above, in the case of Inventive Examples 1 to 8, which satisfy the conditions proposed by the present invention, the corrosion resistance is excellent, whereas in the case of Comparative Examples 1 to 9, which do not satisfy the conditions proposed by the present invention, the corrosion resistance is at a low level.

[0075] [Explanation of the symbol]

[0076] 1: Zn-Al-Mg plated steel

[0077] 10: Base steel plate

[0078] 20: Zn-Al-Mg-based plating layer

[0079] 22: Lost parts

[0080] 24: Weld bead

[0081] 30: Thermal spray coating layer

[0082] 32: Zn thermal spray coating layer

[0083] 34: Al thermal spray coating layer

[0084] 100: Welding device

[0085] 200: Weld bead removal device

[0086] 300: First thermal spray coating device

[0087] 400: Second thermal spray coating device

[0088] D: Hero Street

Claims

1. A Zn-Al-Mg-based plating layer is formed on at least one surface of a base steel sheet, and The above Zn-Al-Mg-based plating layer has a missing portion, and A thermal spray coating layer is formed within the above-mentioned loss portion, and The above thermal spray coating layer comprises a Zn thermal spray coating layer; and an Al thermal spray coating layer formed on the Zn thermal spray coating layer. The above thermal spray coating layer has an average thickness deviation of 70% or less, and The area of ​​pore defects within the above thermal spray coating layer is 9.5% or less, and Zn-Al-Mg plated steel with an average thickness of the above thermal spray coating layer of 30 to 100 μm.

2. In Paragraph 1, Zn-Al-Mg plated steel material having a thickness ratio of the Zn thermal spray coating layer to the above thermal spray coating layer of 30~70%.

3. In Paragraph 1, Zn-Al-Mg plated steel material having a thickness ratio of the Al thermal spray coating layer to the above thermal spray coating layer of 30~70%.

4. In Paragraph 1, The above Zn-Al-Mg plated steel is a Zn-Al-Mg plated steel having the shape of a steel pipe or a square pipe.

5. A step of preparing a base steel sheet having a Zn-Al-Mg-based plating layer formed on at least one surface; A step of forming a loss portion in the above Zn-Al-Mg-based plating layer; The method includes the step of applying a thermal spray coating to form a thermal spray coating layer on the above-mentioned lost portion; The above-mentioned step of thermal spray coating comprises: a step of forming a Zn thermal spray coating layer; and a step of forming an Al thermal spray coating layer on the Zn thermal spray coating layer; and A method for manufacturing a Zn-Al-Mg plated steel material that satisfies the following [Equation 1] during the above thermal spray coating step. [Relationship 1] 54 ≤(-66.3X+68Y+D 2 ) / 60+50 ≤ 76 (However, in the above [Equation 1], X represents the feed speed of the base steel plate, Y represents the spray speed of the thermal spray material, and D represents the spray distance.) 6. In Paragraph 5, A method for manufacturing Zn-Al-Mg plated steel material, comprising the step of forming the above-mentioned loss portion by forming the base steel plate into the shape of a steel pipe, welding it, and then removing the weld bead.

7. In Paragraph 5, A method for manufacturing Zn-Al-Mg plated steel, wherein the transfer speed (X) of the substrate steel plate during the above thermal spray coating step is 8 to 50 m / min.

8. In Paragraph 5, A method for manufacturing Zn-Al-Mg plated steel, wherein the spray speed (Y) of the thermal spray material during the above thermal spray coating step is 3 to 10 m / min.

9. In Paragraph 5, A method for manufacturing a Zn-Al-Mg plated steel material in which, during the above-mentioned thermal spray coating step, the spray distance (D) is 35 to 45 mm.

10. In Paragraph 5, A method for manufacturing Zn-Al-Mg plated steel, further comprising the step of forming the base steel plate into the shape of a square tube after the above-mentioned thermal spray coating step.

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