Plated steel sheet with excellent degreasing properties and its manufacturing method

Abstract

The present invention relates to a highly corrosion-resistant alloy-plated steel sheet containing magnesium, which has excellent degreasing properties, and a method for producing the same.

Description

[Technical Field]

[0001] The present invention relates to a highly corrosion-resistant alloy-plated steel sheet containing magnesium, which has excellent degreasing properties, and a method for producing the same. [Background technology]

[0002] When exposed to a corrosive environment, zinc-based coated steel sheets exhibit sacrificial corrosion protection, which inhibits corrosion of the steel material because zinc, which has a lower redox potential than iron, corrodes first. Furthermore, as the zinc in the coating layer oxidizes, it forms dense corrosion deposits on the steel surface, insulating the steel material from the oxidizing atmosphere and improving the corrosion resistance of the steel material. Thanks to these advantageous properties, zinc-based coated steel sheets have recently been expanding their application range to include steel sheets for building materials, home appliances, and automobiles.

[0003] However, the corrosive environment is gradually worsening due to increased air pollution caused by industrial advancement, and strict regulations on resource and energy conservation are creating a need for the development of steel materials with better corrosion resistance than conventional zinc-based coated steel sheets.

[0004] To address these issues, various studies are being conducted on manufacturing technologies for zinc alloy-coated steel sheets that further improve the corrosion resistance of steel by adding elements such as aluminum (Al) and magnesium (Mg) to the zinc coating bath. A typical example is Al-Mg-Zn highly corrosion-resistant alloy-coated steel sheets that contain zinc (Zn), magnesium (Mg), and aluminum (Al).

[0005] However, even in the case of such highly corrosion-resistant alloy-plated steel sheets, poor degreasing after application of rust-preventive oil has caused problems in subsequent treatment processes such as phosphate treatment and Zr treatment. However, to date, no technology has been developed at a level that can meet the high-grade demand for highly corrosion-resistant Al-Mg-Zn-based alloy-plated steel sheets that also have excellent degreasing properties. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent Publication No. 2013-0133358 Summary of the Invention [Problem to be solved by the invention]

[0007] One aspect of the present invention is to provide a plated steel sheet with excellent degreasing properties and a method for producing the same.

[0008] Alternatively, still another aspect of the present invention is to provide a plated steel sheet that has excellent degreasing properties and high corrosion resistance, and a method for producing the same.

[0009] The object of the present invention is not limited to the above content. Anyone having ordinary skill in the art to which the present invention pertains will have no difficulty in understanding further object of the present invention from the entire content of the specification of the present invention. [Means for solving the problem]

[0010] One aspect of the present invention is Base steel sheet; a surface coating layer provided on at least one surface of the base steel sheet; and an Al-Mg-Zn-based plating layer provided between the base steel sheet and the surface coating layer; The surface coating layer is a metal coating layer made of one or more metals selected from the group consisting of Fe, Zn, Al, and Si; The present invention provides a plated steel sheet having a water-based coating layer containing one or more components selected from the group consisting of P, Zn, Mn, Mo, and B.

[0011] Furthermore, still another aspect of the present invention is Immersing the base steel sheet in an Al-Mg-Zn-based coating bath to form an Al-Mg-Zn-based coating layer on the surface of the base steel sheet; and forming a surface coating layer on the surface of the Al-Mg-Zn-based plating layer; The step of forming the surface coating layer comprises: forming a metal coating layer made of one or more materials selected from the group consisting of Fe, Zn, Al, and Si by a method selected from the group consisting of physical vapor deposition, electroplating, and electroless plating; The present invention provides a method for producing a plated steel sheet, which comprises applying a coating solution containing an oxide, hydroxide, or water-soluble salt of one or more components selected from the group consisting of P, Zn, Mn, Mo, and B, and a solvent, to the Al-Mg-Zn-based plating layer, and then heating and drying the coating solution to form a water-based coating layer. [Effects of the Invention]

[0012] According to one aspect of the present invention, it is possible to provide a plated steel sheet with excellent degreasing properties and a method for manufacturing the same.

[0013] According to yet another aspect of the present invention, it is possible to provide a plated steel sheet having excellent degreasing properties and high corrosion resistance, and a method for producing the same.

[0014] The various yet significant advantages and effects of the present invention are not limited to the above, but can be more easily understood in the course of describing specific embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more completely explain the present invention to those having average knowledge in the art.

[0016] The meaning of "comprises" as used in the specification is to specify features and does not exclude the presence or addition of other features.

[0017] Unless otherwise specified, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Dictionary-defined terms are to be interpreted to have a meaning consistent with the relevant technical literature and the presently disclosed content.

[0018] Hereinafter, a plated steel sheet according to one aspect of the present invention will be described in detail. In the present invention, the content of each element is expressed in percent by weight unless otherwise specified.

[0019] Although conventional Al-Mg-Zn-plated steel sheets have superior corrosion resistance compared to Zn-plated steel sheets, Al-Mg-Zn-plated steel sheets have the problem of poor degreasing. Specifically, Al-Mg-Zn-plated steel sheets have poor degreasing properties after application of rust-preventive oil, which causes problems in subsequent chemical conversion treatment processes such as phosphate treatment and Zr treatment.

[0020] One of the causes of this degreasing problem is magnesium (Mg), which is added to the plating layer to improve corrosion resistance. It is understood that the oxides generated by Mg's strong oxygen affinity and the surfactant components in the rust preventative oil adsorb to each other, resulting in a deterioration in degreasing ability.

[0021] Therefore, if direct contact between magnesium oxide and rust-preventive oil could be prevented, the degreasing problem of highly corrosion-resistant alloy-plated steel sheets could be solved. However, when applied to automotive steel sheets, contact between magnesium oxide and rust-preventive oil must usually be prevented through a method that does not affect subsequent processes such as phosphate treatment and Zr treatment.

[0022] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by forming a surface coating layer on the surface of an Al-Mg-Zn based plating layer that can act as a barrier layer to prevent interaction between the Mg component in the plating layer and the rust preventive oil, and have thus completed the present invention. The configuration of the present invention will be specifically described below.

[0023] A plated steel sheet according to one aspect of the present invention includes a base steel sheet; a surface coating layer provided on at least one surface of the base steel sheet; and an Al-Mg-Zn-based plating layer provided between the base steel sheet and the surface coating layer.

[0024] In the present invention, the type of base steel sheet is not particularly limited. For example, the base steel sheet may be an Fe-based base steel sheet used as a base steel sheet for conventional zinc-based coated steel sheets, i.e., a hot-rolled steel sheet or a cold-rolled steel sheet, but is not limited thereto. Alternatively, the base steel sheet may be, for example, a carbon steel, an ultra-low carbon steel, or a high manganese steel used as a material for construction, home appliances, or automobiles, or may be stainless steel. Meanwhile, in the case of carbon steel, ultra-low carbon steel, medium-low carbon steel, low carbon steel, and carbon steel all exhibit similar effects, so there is no need to particularly limit the steel composition, and the steel is hardly affected by elements such as Mn, Si, Ti, Nb, and B, which are added in large amounts to high-strength steel and ultra-high-strength steel. On the other hand, an example of the above-mentioned base steel sheet is one containing, in weight percent, C: more than 0% and not more than 0.18%, Si: more than 0% and not more than 1.5%, Mn: 0.01 to 2.70%, P: more than 0% and not more than 0.07%, S: more than 0% and not more than 0.015%, Al: more than 0% and not more than 0.5%, Nb: 0.06% or less (including 0%), Cr: 1.1% or less (including 0%), Ti: 0.06% or less (including 0%), B: 0.03% or less (including 0%), the balance being Fe and other unavoidable impurities. Alternatively, yet another example of the above-mentioned base steel sheet includes, in weight percent, C: more than 0% and not more than 0.18%, Si: more than 0% and not more than 1.5%, Mn: 0.01 to 2.70%, P: more than 0% and not more than 0.07%, S: more than 0% and not more than 0.015%, Al: more than 0% and not more than 0.5%, Nb: more than 0% and not more than 0.06%, Cr: more than 0% and not more than 1.1%, Ti: more than 0% and not more than 0.06%, B: more than 0% and not more than 0.03%, and the balance being Fe and other unavoidable impurities.

[0025] According to one aspect of the present invention, a surface coating layer, which will be described later, may be provided on at least one surface of the base steel sheet. The surface coating layer may be formed on only one surface of the base steel sheet, or on both surfaces of the base steel sheet.

[0026] According to one aspect of the present invention, an Al-Mg-Zn-based plating layer may be provided between the base steel sheet and the surface coating layer. Although not particularly limited, the Al-Mg-Zn-based plating layer in this specification refers to a plating layer containing Mg and Al, with Zn as the main component (i.e., more than 50 wt %).

[0027] Although not particularly limited, according to one aspect of the present invention, the Al-Mg-Zn-based plating layer may contain, by weight %, 0.1 to 15.0% Mg, 1.5 to 15.0% Al, the remainder being Zn and other unavoidable impurities.

[0028] Mg: 0.1 to 15.0% Magnesium (Mg) is an element that plays a role in improving the corrosion resistance of plated steel sheets, and in order to ensure the high corrosion resistance targeted in the present invention, the Mg content in the coating layer can be set to 0.1% or more. However, if the Mg content is excessive, dross may be generated, so the Mg content can be set to 15.0% or more.

[0029] Al:1.5~15.0% Generally, the addition of magnesium improves corrosion resistance, but as the magnesium content increases, the oxidation of magnesium increases the amount of floating dross in the coating bath, necessitating frequent removal of the dross. To solve this problem, 1.5% or more of aluminum can be added to the coating layer. However, if too much aluminum is added to suppress dross, the melting point of the coating bath increases, which can lead to excessively high operating temperatures, causing problems with high-temperature work, such as erosion of the coating bath structure and deterioration of the steel. Therefore, the aluminum content can be limited to 15.0% or less.

[0030] The balance is Zn and other unavoidable impurities In addition to the above-mentioned composition of the coating layer, the balance may be Zn and other inevitable impurities. The inevitable impurities may include all impurities that are unintentionally mixed in during the normal manufacturing process of a hot-dip galvanized steel sheet, and the meaning thereof will be easily understood by those skilled in the art.

[0031] According to an embodiment of the present invention, the Al-Mg-Zn-based plating layer may further include at least one of the following groups (a) to (h):

[0032] However, since the elements in each of the following groups are not essential elements for achieving the object of the present invention, there is no lower limit for their content. Therefore, even if not specifically mentioned below, the lower limit for the content of each element may be 0%. (a) One or more of the following: Si: 0.5% or less, Ni: 0.5% or less (b) One or more 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 (c)Ti: 0.1% or less (d)W: 0.5% or less (e)Cu: 2.0% or less (f) One or more of the following: Fe: 1.0% or less, Cr: 0.5% or less, Mn: 0.5% or less, V: 0.5% or less (g) One or more of the following: B: 0.1% or less, P: 0.1% or less (h) One or more of Sn: 1.0% or less, Sb: 1.0% or less, and Bi: 1.0% or less

[0033] (a) One or more of the following: Si: 0.5% or less, Ni: 0.5% or less Silicon has the effect of preventing Fe-Zn alloying by forming Mg2Si at the interface and preventing excessive formation of Fe-Al alloy phases. However, if its content exceeds 0.5%, the melting point of the plating bath increases and there is a risk of increased brittleness due to excessive formation of Mg2Si. Ni has the effect of preventing Fe diffusion by forming an Al-Ni alloy phase, but if its content exceeds 0.5%, there is a risk of excessively increasing the cost of auxiliary materials.

[0034] (b) One or more 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 Ca, La, Ce, Y, and Sr are effective in preventing oxidation of magnesium in the plating bath by forming an oxide film. However, if their contents exceed 1.0%, 0.1%, 0.1%, 0.1%, and 1.0%, respectively, Ca may cause a problem of increased dross due to increased oxides, while La, Ce, Y, and Sr may cause a problem of reduced plating properties due to increased viscosity of the plating bath.

[0035] (c)Ti: 0.1% or less Ti acts as a nucleation site for Ti-Al intermetallic compounds, resulting in the refinement of crystal grains (spangles). However, if the content exceeds 0.1%, the melting point of the plating bath increases, which can lead to problems with increased dross.

[0036] (d)W: 0.5% or less W forms W oxide on the surface and has the effect of improving corrosion resistance, but if its content exceeds 0.5%, there may be a problem in that the melting point of the plating bath increases.

[0037] (e)Cu: 2.0% or less Cu has the effect of forming an Al-Cu process structure and reducing the hardness of the coating layer, but if its content exceeds 2.0%, it may cause a problem of spangles becoming coarse.

[0038] (f) One or more of the following: Fe: 1.0% or less, Cr: 0.5% or less, Mn: 0.5% or less, V: 0.5% or less Fe, Cr, Mn and V have the effect of preventing electrode deterioration by quickly dissipating the liquid phase and suppressing alloying between zinc and the welding electrode. However, if their contents exceed 1.0%, 0.5%, 0.5% and 0.5%, respectively, there may be a problem in that the melting point of the plating bath rises excessively.

[0039] (g) One or more of the following: B: 0.1% or less, P: 0.1% or less B and P have the effect of suppressing LME cracks in welds, but if their contents exceed 0.1% each, there may be a problem of increased occurrence of dross.

[0040] (h) One or more of Sn: 1.0% or less, Sb: 1.0% or less, and Bi: 1.0% or less Sn, Sb and Bi have the effect of making spangles uniform and improving pot durability by lowering the plating bath temperature, but if their contents exceed 1.0% each, there may be a problem of coarsening of spangles.

[0041] In order to effectively serve as the barrier layer, the surface coating layer may be a metallic coating layer or a water-based coating layer, each of which will be described separately below.

[0042] First, in order for the above-mentioned metal coating layer to effectively function as a barrier layer that prevents interaction between Mg in the plating layer and the rust-preventive oil, the metal coating layer can be made of one or more elements selected from the group consisting of Fe, Zn, Al, and Si. That is, since the metal coating layer is a barrier layer that prevents interaction between Mg and the rust-preventive oil, it is preferable that it does not contain Mg, and it can be made of one or more elements selected from the group consisting of Fe, Zn, Al, and Si, or more preferably, it can be an Fe plating layer, a Zn plating layer, or an Al plating layer.

[0043] Although not particularly limited, according to one aspect of the present invention, the average thickness of the metal coating layer may be 10 to 3000 nm. In order for the metal coating layer to effectively function as a barrier layer that effectively prevents the interaction between oxides resulting from Mg in the plating layer and the rust-preventive oil, the average thickness of the metal coating layer may be 10 nm or more. On the other hand, if the thickness of the metal coating layer is excessive, it is economically disadvantageous in consideration of the coating time and the amount of coating material used, and corrosion resistance is also insufficient, so the upper limit of the average thickness may be set to 3000 nm.

[0044] On the other hand, in order to further improve the above-mentioned effects, the lower limit of the average thickness of the metal coating layer may be 20 nm, or the upper limit of the average thickness of the metal coating layer may be 1000 nm.

[0045] Although not particularly limited, according to one aspect of the present invention, the metal coating layer may satisfy the following relational expression 1. [Equation 1] 0.003≦Ts / Tp≦0.400 (In the above relational expression 1, Tp represents the average thickness of the Al-Mg-Zn-based plating layer, and Ts represents the average thickness of the metal coating layer.)

[0046] In this case, in the above Relational Formula 1, the units of Tp and Ts are not particularly limited as long as they are the same.

[0047] Although not particularly limited, according to one aspect of the present invention, the metal coating layer may be formed by one method selected from the group consisting of physical vapor deposition, electroplating, and electroless plating using one or more materials selected from the group consisting of Fe, Zn, Al, and Si. However, as a preferred example, the metal coating layer may be formed by physical vapor deposition (PVD) sputtering, which can easily form a thin metal coating layer with an average thickness ranging from 10 to 3,000 nm.

[0048] According to one aspect of the present invention, as described above, providing a metal coating layer on at least one surface of an Al-Mg-Zn-based plating layer not only effectively prevents interaction between Mg in the plating layer and the rust-preventive oil, but also enables subsequent chemical conversion treatments such as phosphate treatment or Zr treatment.

[0049] Meanwhile, in order for the above-mentioned water-based coating layer to effectively function as a barrier layer that prevents interaction between Mg in the plating layer and the rust-preventive oil, the water-based coating layer may contain one or more components selected from the group consisting of P, Zn, Mn, Mo, and B. In this case, the water-based coating layer may refer to a coating layer that is hydrophilic. That is, as will be described later, it may refer to a coating layer that can be dissolved in a hydrophilic solvent such as an aqueous solution or an alkaline solution, and therefore the water-based coating layer can be removed by treatment with the hydrophilic solvent such as an aqueous solution or an alkaline solution.

[0050] Although not particularly limited, according to one aspect of the present invention, the water-based coating layer can be formed by applying a coating solution containing an oxide, hydroxide, or water-soluble salt of one or more components selected from the group consisting of P, Zn, Mn, Mo, and B, and a solvent, to the Al-Mg-Zn-based plating layer and then heating and drying it. Specifically, the water-based coating layer can be formed by applying the coating solution to the Al-Mg-Zn-based plating layer and then heating and drying it at 80 to 100°C for 10 seconds or less (excluding 0 seconds).

[0051] For example, a coating solution containing the boric acid-based oxide, hydroxide, and water-soluble salt or the phosphoric acid-based oxide, hydroxide, and water-soluble salt, and a solvent can be applied to the Al-Mg-Zn-based plating layer and dried by heating, thereby forming the water-based coating layer.

[0052] Although not particularly limited, according to one aspect of the present invention, the aqueous coating layer may contain one or more components selected from the group consisting of P and B, or the aqueous coating layer may contain 5 to 45% by weight of one or more components selected from the group consisting of P and B.

[0053] Alternatively, although not particularly limited thereto, according to one aspect of the present invention, the waterborne coating layer may contain one or more components selected from the group consisting of P and B; and one or more components selected from the group consisting of Zn, Mn, and Mo.

[0054] Although not particularly limited, according to one aspect of the present invention, the aqueous coating layer may contain 5 to 45% by weight of one or more components selected from the group consisting of P and B, and / or 2.5 to 30.0% by weight of one or more components selected from the group consisting of Zn, Mn, and Mo.

[0055] Although not particularly limited, according to one aspect of the present invention, the coating amount of the aqueous coating layer per side is 100.0 to 900.0 mg / m 2 The coating amount of the water-based coating layer on one side can be 100.0 mg / m 2 By setting the coating amount to 900.0 mg / m or more, contact between the anti-rust oil and the plating layer can be effectively prevented, and good degreasing properties can be ensured. 2 If the value exceeds this, problems may arise in weldability and economy due to an increase in the amount of raw material used.

[0056] Although not particularly limited, in order to further improve the above-mentioned effects, when the aqueous coating layer contains P, B, and Mo, the coating amount per side is 100.0 to 900.0 mg / m 2 Similarly, when the water-based coating layer contains P, Mn, and Zn, the coating amount per side can be 100.0 to 900.0 mg / m 2 It can be said that:

[0057] Meanwhile, the water-based coating layer may be a water-soluble coating containing one or more components selected from the group consisting of P, Zn, Mn, Mo, and B, and may be formed by the above-mentioned method using a coating solution having a pH of 2 or higher and containing 20% ​​or less (excluding 0%) of phosphoric acid or boric acid, which reacts with the plating layer. The water-based coating layer thus formed is a water-soluble coating layer, and must be dissolvable in an aqueous or alkaline solution for the subsequent chemical conversion treatment process, and may have a removal rate of 80% or more upon dissolution.

[0058] According to one aspect of the present invention, by providing a water-based coating layer on at least one surface of an Al-Mg-Zn-based coating layer as described above, it is possible to effectively prevent interaction between the Mg in the coating layer and the rust-preventive oil, and also to make the water-based coating layer removable in a water-rinsing or degreasing process. As a result, by removing the water-based coating layer after the degreasing process, it is possible to provide a plated steel sheet using a removable coating layer that does not affect subsequent chemical conversion treatments such as phosphate treatment or Zr treatment.

[0059] A method for producing a plated steel sheet according to still another aspect of the present invention will now be described.

[0060] A base steel sheet is immersed in an Al-Mg-Zn-based coating bath to form an Al-Mg-Zn-based coating layer on the surface of the base steel sheet. The composition of the Al-Mg-Zn-based coating bath and the content of each component are the same as those of the Al-Mg-Zn-based coating layer described above. Therefore, the explanations for the reasons for adding each component and limiting the content of each component of the coating layer described above can be similarly applied to the Al-Mg-Zn-based coating bath.

[0061] Next, a surface coating layer is formed on the surface of the Al-Mg-Zn-based plating layer.

[0062] The surface coating layer can be formed by a method selected from the group consisting of physical vapor deposition, electroplating, and electroless plating using one or more materials selected from the group consisting of Fe, Zn, Al, and Si to form a metal coating layer consisting of one or more elements selected from the group consisting of Fe, Zn, Al, and Si. Alternatively, a coating solution containing oxides, hydroxides, and water-soluble salts of one or more elements selected from the group consisting of P, Zn, Mn, Mo, and B and a solvent can be applied to the Al-Mg-Zn-based plating layer, followed by heating and drying to form a water-based coating layer. The solvent can be any water-soluble solvent commonly used in the art, and is not particularly limited, and a representative example is water.

[0063] In this case, the above description of the plated steel sheet is similarly applicable to the surface coating layer.

[0064] Meanwhile, although not particularly limited, according to one aspect of the present invention, when forming the aqueous coating layer, the coating solution may be applied to the Al-Mg-Zn-based plating layer, and then heat-treated at 80 to 100°C for 10 seconds or less (excluding 0 seconds) to heat-dry the layer. [Example]

[0065] (Example) The present invention will be described in more detail below through examples. However, it should be noted that the following examples are intended to illustrate and embody the present invention and are not intended to limit the scope of the present invention, as the scope of the present invention is determined by the matters described in the claims and matters reasonably inferred therefrom.

[0066] (Experimental Example 1) An Al-Mg-Zn-based plating layer composed of 1.2% Mg, 1.7% Al, and the remainder Zn and other unavoidable impurities was formed on the surface of the base steel sheet to an average thickness of 8 μm, and then a metal coating layer was formed as a surface coating layer on the surface of the Al-Mg-Zn-based plating layer using a physical vapor deposition (PVD) sputtering method under the conditions listed in Table 1 below. Test specimens were manufactured in which the average thickness of the surface coating layer was adjusted by controlling the coating time as listed in Table 1 below.

[0067] Next, to evaluate degreasing ability, test pieces were immersed in Panyu 90EG rust-preventive oil and then set upright for 72 hours. After that, they were degreased for 90 seconds in a degreasing solution using Nippon Felt Co., Ltd. EC-90 degreasing solution. The water wettability of the test piece surface was evaluated, with a rating of "△" when the surface water wettability was 80% or more but less than 90%, a rating of "○" when it was 90% or more (including 100%), and an "×" otherwise, as shown in Table 1 below.

[0068] In addition, to evaluate the phosphate treatability, each test piece was subjected to surface conditioning and phosphate treatment according to the usual automobile manufacturer's standards, and then the uniformity of the phosphate was evaluated, with a rating of "○" indicating that the phosphate was formed uniformly and a rating of "×" indicating that the phosphate was formed unevenly.

[0069] [Table 1]

[0070] As can be seen from the results in Table 1 above, it was confirmed that in the case of Inventive Examples 1 to 8, which had a metal coating layer as the surface coating layer according to the present invention, the degreasing property was superior to that of Comparative Examples 1 to 3. In particular, it was confirmed that in the case of Inventive Examples 2 to 4 and 6 to 8, in which the metal coating layer had an average thickness of 20 nm or more, the degreasing property was even superior to that of Inventive Examples 1 and 5.

[0071] On the other hand, in the case of Comparative Example 1 in which no surface coating layer was formed on the surface of the Al-Mg-Zn based plating layer, it was confirmed that the degreasing properties and phosphate treatment properties were significantly deteriorated.

[0072] On the other hand, in the case of Comparative Examples 2 and 3, which had a Ni metal layer as the metal coating layer, it was confirmed that, despite the increase in thickness of the surface coating layer, it was not possible to prevent the Al-Mg-Zn-based plating layer from adsorbing the rust-preventive oil, resulting in a deterioration in degreasing properties.

[0073] (Experimental Example 2) As in Experimental Example 1, an Al-Mg-Zn-based plating layer was formed on the surface of a base steel sheet. To form a water-based coating layer as a surface coating layer on the surface of the Al-Mg-Zn-based plating layer, phosphoric acid-based aqueous solution 1 containing a hypophosphorous acid solution, ethanol, zinc oxide, and manganese, and boric acid-based aqueous solution 2 containing ammonium pentaborate, ammonium molybdate, and ethanol were prepared. As shown in Table 2 below, each of the phosphoric acid-based aqueous solution 1 and boric acid-based aqueous solution 2 was applied to the surface of the Al-Mg-Zn-based plating layer by roll coating in the amount shown in Table 2 below. The coated steel sheet was then heated and dried to 80°C (based on the surface temperature) within 10 seconds to form a water-based coating layer containing one or more components selected from the group consisting of P, Zn, Mn, Mo, and B.

[0074] Next, the degreasing property and phosphating property were evaluated in the same manner as in Experimental Example 1, and the results are shown in Table 2 below.

[0075] [Table 2]

[0076] As can be seen from the results in Table 2 above, it was confirmed that Inventive Examples 9 to 18, which had a water-based coating layer as the surface coating layer according to the present invention, exhibited superior degreasing properties and / or phosphate treatability compared to Comparative Example 4. It was also confirmed that Inventive Examples 9 to 18 had the water-based coating layer completely removed (stripped) during treatment with an aqueous or alkaline solution, with a removal rate of 80% or more (including 100%). It was also confirmed that the plated steel sheets obtained from Inventive Examples 9 to 18 contained 5 to 45% by weight of one or more components selected from the group consisting of P and B, and 2.5 to 30.0% by weight of one or more components selected from the group consisting of Zn, Mn, and Mo.

[0077] In particular, among Examples 9 to 13 containing B, Mo, and an amine compound as the water-based coating layer, those having a coating weight per side of 100.0 to 900.0 mg / m 2 It was confirmed that invention examples 10 to 13, which satisfy the above condition, are more effective than invention example 9 in improving degreasing properties by preventing contact between the rust preventive oil and the surface of the plating layer.

[0078] In addition, among Examples 14 to 18 containing P, Mn, and Zn as the water-based coating layer, those having a coating weight per side of 100.0 to 900.0 mg / m 2 It was confirmed that invention examples 16 to 18, which satisfy the above condition, are more effective in improving degreasing properties by preventing contact between the rust preventive oil and the surface of the plating layer than invention examples 14 and 15.

[0079] On the other hand, in the case of Comparative Example 4 in which no surface coating layer was formed on the surface of the Al-Mg-Zn based plating layer, it was confirmed that the degreasing properties and phosphate treatment properties were significantly deteriorated.

Claims

1. Base steel sheet; a surface coating layer provided on at least one surface of the base steel sheet; and an Al-Mg-Zn-based plating layer provided between the base steel sheet and the surface coating layer; The surface coating layer is a metal coating layer made of one or more metals selected from the group consisting of Fe, Zn, Al, and Si; A plated steel sheet having a water-based coating layer containing one or more components selected from the group consisting of P, Zn, Mn, Mo, and B.

2. 2. The plated steel sheet according to claim 1, wherein the Al-Mg-Zn based plating layer contains, by weight %, 0.1 to 15.0% Mg, 1.5 to 15.0% Al, the balance being Zn and other inevitable impurities.

3. The plated steel sheet according to claim 2, wherein the plating layer further includes any one or more of the following groups (a) to (h): (a) One or more of Si: 0.5% or less and Ni: 0.5% or less (b) one or more of Ca: 1.0% or less, La: 0.1% or less, Ce: 0.1% or less, Y: 0.1% or less, and Sr: 1.0% or less (c) Ti: 0.1% or less (d) W: 0.5% or less (e) Cu: 2.0% or less (f) one or more of Fe: 1.0% or less, Cr: 0.5% or less, Mn: 0.5% or less, and V: 0.5% or less (g) One or more of B: 0.1% or less, P: 0.1% or less (h) one or more of Sn: 1.0% or less, Sb: 1.0% or less, and Bi: 1.0% or less

4. The plated steel sheet according to claim 1, wherein the metal coating layer has an average thickness of 10 to 3000 nm.

5. The plated steel sheet according to claim 1 , wherein the metal coating layer satisfies the following relational expression 1: [Relationship 1] 0.003≦Ts / Tp≦0.4 (In the above-mentioned relational expression 1, Tp represents the average thickness of the Al-Mg-Zn-based plating layer, and Ts represents the average thickness of the metal coating layer.)

6. The coating amount of the water-based coating layer per side is 100.0 to 900.0 mg / m ２ The plated steel sheet according to claim 1 , wherein

7. The plated steel sheet according to claim 1 , wherein the water-based coating layer contains one or more components selected from the group consisting of P and B.

8. 2. The plated steel sheet according to claim 1, wherein the water-based coating layer contains 5 to 45% by weight of one or more components selected from the group consisting of P and B.

9. The aqueous coating layer is One or more components selected from the group consisting of P and B; and The plated steel sheet according to claim 1, further comprising one or more elements selected from the group consisting of Zn, Mn, and Mo.

10. 2. The plated steel sheet according to claim 1, wherein the water-based coating layer contains 2.5 to 30.0% by weight of one or more components selected from the group consisting of Zn, Mn, and Mo.

11. 2. The plated steel sheet according to claim 1, wherein the metal coating layer is formed by one method selected from the group consisting of a physical vapor deposition method, an electroplating method, and an electroless plating method using one or more materials selected from the group consisting of Fe, Zn, Al, and Si.

12. The aqueous coating layer is 2. The plated steel sheet according to claim 1, wherein the plated steel sheet is formed by applying a coating solution containing an oxide, hydroxide, or water-soluble salt of one or more components selected from the group consisting of P, Zn, Mn, Mo, and B; and a solvent to the Al-Mg-Zn based plating layer, and then heating and drying the coating solution.

13. The water-based coating layer contains P, B, and Mo, and the coating amount per side is 100.0 to 900.0 mg / m ２ The plated steel sheet according to claim 1 , wherein

14. The water-based coating layer contains P, Mn, and Zn, and the coating amount per side is 100.0 to 900.0 mg / m ２ The plated steel sheet according to claim 1 , wherein

15. The plated steel sheet according to claim 1 , wherein the water-based coating layer has a removal rate of 80% or more (including 100%) when treated with an aqueous solution or an alkaline solution.

16. Immersing the base steel sheet in an Al-Mg-Zn-based coating bath to form an Al-Mg-Zn-based coating layer on the surface of the base steel sheet; and forming a surface coating layer on the surface of the Al-Mg-Zn based plating layer; The step of forming the surface coating layer comprises: forming a metal coating layer made of at least one material selected from the group consisting of Fe, Zn, Al, and Si by a method selected from the group consisting of physical vapor deposition, electroplating, and electroless plating; A method for producing a plated steel sheet, comprising: applying a coating solution containing an oxide, hydroxide, or water-soluble salt of one or more components selected from the group consisting of P, Zn, Mn, Mo, and B; and a solvent to the Al-Mg-Zn-based plating layer, and then heating and drying the coating solution to form a water-based coating layer.

17. The method for producing a plated steel sheet according to claim 16, wherein the heat drying is performed at 80 to 100°C for 10 seconds or less (excluding 0 seconds).

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