Copper plated austenitic stainless steel coil

Abstract

According to the present invention, there may be provided a copper plated austenitic stainless steel coil comprising: an austenitic stainless steel coil base material; and a copper plating layer provided on the outer surface of the base material, wherein the copper plating layer has an average thickness of 1-100 mu or less, and a ratio of the average thickness of the copper plating layer to the average thickness of the austenitic stainless steel coil base material is 0.2 or less.

Description

Copper-plated austenitic stainless steel coil

[0001] The present invention relates to a copper-plated austenitic stainless steel coil.

[0002] Copper plating on stainless steel surfaces can be used for brazing, taking advantage of its lower melting point compared to stainless steel. However, examples of plating on the surface of stainless steel coils are rare.

[0003] Meanwhile, from a plating perspective, there are cases of nickel plating to improve surface conductivity and aluminum plating to enhance saltwater corrosion resistance. However, copper plating on stainless steel coils is rare.

[0004] In addition, although there is a method of overlapping copper through a cladding method for the purpose of improving the conductivity of the stainless steel surface, it is difficult to find examples of implementing copper on the surface of a stainless steel coil through a plating method.

[0005] Stainless steel typically forms a passive film to provide corrosion resistance. This passive film, composed primarily of chromium and oxygen compounds, is uniformly and densely distributed on the surface. Therefore, copper plating does not adhere well to the surface. Furthermore, even after plating, the plating layer is prone to peeling when forming a copper-plated stainless steel product. The present invention aims to address this problem of copper plating on stainless steel coils caused by the passive film.

[0006] A method for manufacturing a product in which copper is plated on the surface of a stainless steel coil is provided.

[0007] A copper-plated austenitic stainless steel coil according to one embodiment of the present invention comprises: an austenitic stainless steel coil base material; and a copper plating layer provided on an outer surface of the base material, wherein an average thickness of the copper plating layer is 1 µm to 100 µm or less, and a ratio of the average thickness of the copper plating layer to the austenitic stainless steel coil base material is 0.2 or less.

[0008] In addition, the copper-plated austenitic stainless steel coil according to one embodiment of the present invention can satisfy a film index of 1.2 or less, expressed as (Si+2Al) / Mn, of the austenitic stainless steel coil base material. (Here, Si, Al, and Mn represent the contents of each element.)

[0009] In addition, in the copper-plated austenitic stainless steel coil according to one embodiment of the present invention, the composition of the austenitic stainless steel coil base material may include, in wt%, C: 0.005 to 0.080%, Si: 0.1 to 1.0%, Mn: 0.1 to 1.5%, Cu: 0.05 to 0.5%, Ni: 8 to 13%, Cr: 16 to 20%, Mo: 0.05 to 2.5%, and Al: 0.001 to 0.2%.

[0010] In addition, a copper-plated austenitic stainless steel coil according to one embodiment of the present invention has a surface area of ​​100x100mm 2 The area ratio of the copper plating layer may be 95% or more.

[0011] In addition, in a copper-plated austenitic stainless steel coil according to one embodiment of the present invention, the copper plating layer may contain copper in an amount of 75% or more by weight.

[0012] Another embodiment of the present invention provides a method for manufacturing a copper-plated austenitic stainless steel coil, comprising the steps of: preparing an austenitic stainless steel coil base material; and immersing the base material in a solution containing 10 g / L to 500 g / L of a solution composed of CuSO4·5H2O, 10 g / L to 500 g / L of H2SO4, and the remainder of water, thereby forming a copper-plated austenitic stainless steel coil at a pressure of 1 A / dm 2 50A / dm 2 A step of electroplating copper by applying a current density of 1 to 150 seconds;

[0013] In addition, in the method for manufacturing a copper-plated austenitic stainless steel coil according to one embodiment of the present invention, the austenitic stainless steel coil base material can satisfy a film index expressed as (Si+2Al) / Mn of 1.2 or less. (Here, Si, Al, and Mn represent the contents of each element.)

[0014] In addition, in the method for manufacturing a copper-plated austenitic stainless steel coil according to one embodiment of the present invention, the composition of the austenitic stainless steel coil base material may include, in wt%, C: 0.005 to 0.080%, Si: 0.1 to 1.0%, Mn: 0.1 to 1.5%, Cu: 0.05 to 0.5%, Ni: 8 to 13%, Cr: 16 to 20%, Mo: 0.05 to 2.5%, and Al: 0.001 to 0.2%.

[0015] In addition, a method for manufacturing a copper-plated austenitic stainless steel coil according to one embodiment of the present invention may include a step of immersing in a sulfuric acid having a concentration of 5 g / L to 200 g / L or a mixed acid of nitric acid and hydrofluoric acid having a concentration of 1 g / L to 20 g / L for 1 second to 120 seconds before plating copper.

[0016] As presented in the present invention, the copper-plated austenitic stainless steel has excellent brazing properties and excellent resistance to peeling of the copper-plated layer when formed.

[0017] Figure 1 is a cross-sectional view of a copper-plated austenitic stainless steel coil including a stainless steel coil base material and a copper plating layer.

[0018] Figure 2 is a photograph showing the external characteristics of Invention Example 1.

[0019] Figure 3 is a photograph showing the external characteristics of Comparative Example 1.

[0020] Preferred embodiments of the present invention are described below. However, the embodiments of the present invention may be modified in various ways, and the technical concept of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more fully explain the present invention to those of ordinary skill in the art.

[0021] The terminology used in this application is solely for the purpose of describing specific examples. Therefore, for example, singular expressions include plural expressions unless the context clearly dictates otherwise. Additionally, it should be noted that terms such as "comprise" or "have" used in this application are used to clearly indicate the presence of features, steps, functions, components, or combinations thereof described in the specification, and are not used to preliminarily exclude the presence of other features, steps, functions, components, or combinations thereof.

[0022] Meanwhile, unless otherwise defined, all terms used herein should be considered to have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Therefore, unless explicitly defined herein, specific terms should not be interpreted in an overly idealistic or formal sense.

[0023] In addition, the terms "about", "substantially", etc. in this specification are used in the sense of or close to the numerical value when manufacturing and material tolerances inherent to the meanings mentioned are presented, and are used to prevent unscrupulous infringers from unfairly using the disclosure in which exact or absolute numerical values ​​are mentioned to aid understanding of the present invention.

[0024] Unless otherwise specifically stated herein, percentages indicating the content of each element are based on weight.

[0025] First, a copper-plated austenitic stainless steel coil according to the present invention will be described.

[0026] A copper-plated austenitic stainless steel coil according to one embodiment of the present invention comprises: an austenitic stainless steel coil base material; and a copper plating layer provided on an outer surface of the base material, wherein the average thickness of the copper plating layer is 1 µm to 100 µm or less, and a ratio of the average thickness of the copper plating layer to the austenitic stainless steel coil base material is 0.2 or less.

[0027] FIG. 1 is a cross-sectional view of a copper-plated austenitic stainless steel coil, which may include a stainless steel coil base material and a copper plating layer according to one embodiment of the present invention.

[0028] The austenitic stainless steel coil base material of the present invention can satisfy a film index expressed as (Si+2Al) / Mn of 1.2 or less, and must have a microstructure of austenitic stainless steel, but is not limited to a specific composition range. For example, the composition of the austenitic stainless steel coil base material may include, in wt%, C: 0.005 to 0.080%, Si: 0.1 to 1.0%, Mn: 0.1 to 1.5%, Cu: 0.05 to 0.5%, Ni: 8 to 13%, Cr: 16 to 20%, Mo: 0.05 to 2.5%, and Al: 0.001 to 0.2%, but is not limited thereto.

[0029] When the above film index exceeds 1.2, the Si oxide or Al oxide within the passive film is strengthened, which has the effect of further strengthening the characteristics of the passive film. Conversely, this results in inhibiting adhesion with copper. Mn rather inhibits the formation of the passive film, and has the opposite effect to Si or Al. Therefore, the film index is controlled to be 1.2 or less, preferably 1 or less, and more preferably 0.7 or less.

[0030] Meanwhile, copper cladding is also used to improve the conductivity of stainless steel surfaces. However, controlling the thickness of the copper layer to 1-100 ㎛ is much easier than joining it with cladding. Because cladding requires significant costs to thin the copper layer, it is typically manufactured at thicknesses of 100 ㎛ or more, making delamination prone after forming.

[0031] Accordingly, the average thickness of the copper plating layer of the present invention may be 1 µm to 100 µm or less, and the ratio of the average thickness of the copper plating layer to the austenitic stainless steel coil base material may be 0.2 or less. Copper plating may be performed on one or both sides of the austenitic stainless steel coil base material, and in order to prevent copper from peeling when forming after plating the copper, the average thickness of the copper plating layer may be 1 µm to 100 µm or less, preferably 75 µm or less, and more preferably 60 µm or less. Since peeling occurs when the copper plating layer is placed on the inside or outside of the semi-curved surface during forming, and the difference in the forming amount, i.e., elongation, between the stainless steel and the copper plating layer increases, it is necessary to control the thickness of the copper plating layer and the base material coil, and it is necessary to control the thickness ratio of the stainless steel and the copper plating layer to 0.2 or less. It may be preferably 0.1 or less, and more preferably 0.05 or less.

[0032] In addition, 100x100mm of the surface of the copper-plated austenitic stainless steel coil according to one embodiment of the present invention 2 The area ratio of the copper plating layer may be 95% or more.

[0033] If the area ratio of the copper plating layer is less than 95%, the copper cannot function properly in the unplated area, and thus, when the unplated area comes into contact with the joining material during brazing, there is a problem of insufficient bonding in that area. The area ratio of the copper plating layer may preferably be 99% or more.

[0034] In addition, in a copper-plated austenitic stainless steel coil according to one embodiment of the present invention, the copper plating layer may contain copper in an amount of 75% or more by weight.

[0035] The above copper content refers to the average of the copper content when measuring at 5 points in the center layer in the thickness direction of the copper plating layer, and if it is less than 75%, the copper plating may be insufficient and some of the components of the base material may be measured, and in this case, there is a problem that the copper plating layer may peel off during molding. The copper content of the copper plating layer may be preferably 85% or more, and more preferably 95% or more.

[0036] Copper plating that falls short of the aforementioned area ratio or content does not display a uniform copper color on the surface, which detracts from the aesthetic appearance and causes the user to judge that the copper plating is not properly done during a visual inspection.

[0037]

[0038] Next, a method for manufacturing a copper-plated austenitic stainless steel coil is described.

[0039] A method for manufacturing a copper-plated austenitic stainless steel coil according to one embodiment of the present invention comprises the steps of: preparing an austenitic stainless steel coil base material; and immersing the base material in a solution containing 10 g / L to 500 g / L of a solution composed of CuSO4·5H2O, 10 g / L to 500 g / L of H2SO4, and the remainder of water, thereby forming a copper-plated austenitic stainless steel coil at a pressure of 1 A / dm 2 50A / dm 2 A step of electroplating copper by applying a current density of 1 to 150 seconds;

[0040] Copper plating can be performed by various methods, but is preferably performed by electroplating. This is because it is advantageous for production in coil units in conjunction with the aforementioned acid treatment or nickel layer. Electroplating is performed in a solution consisting of 10 to 500 g / L of CuSO4·5H2O, 10 to 500 g / L of H2SO4, and the remainder of water, with the stainless steel as the cathode and the insoluble electrode as the anode, and a current density of 1 to 50 A / dm 2 This can be done by the following method, as it is the optimal condition for copper to adhere to stainless steel without peeling and is a factor that controls the thickness of the copper plating layer. On the other hand, if the concentration of the solution is dilute or the current density is low, the copper will not adhere uniformly and insufficient areas will occur, which will be a factor in lowering the area ratio of the plating layer or measuring low copper content within the plating layer. If the concentration of the solution is too high or the current density is high, the copper layer plated on stainless steel will easily decompose, so it is controlled within the relevant range.

[0041] In addition, the method for manufacturing a copper-plated austenitic stainless steel coil according to one embodiment of the present invention may include a step of immersing the stainless steel coil in a sulfuric acid having a concentration of 5 g / L to 200 g / L or a mixed acid of nitric acid and hydrofluoric acid having a concentration of 1 g / L to 20 g / L for 1 to 120 seconds before plating copper. In order to prevent peeling during forming when plating copper, it is necessary to remove the passive film on the surface of the stainless steel base material. This is because the passive film on the surface of the stainless steel base material increases corrosion resistance, but hinders adhesion with copper. In this case, the method can be improved by immersing the stainless steel base material in sulfuric acid or a mixed acid of nitric acid and hydrofluoric acid for 1 to 120 seconds before copper plating. In order to maximize the reactivity between the passive film and the acid, the concentration of sulfuric acid is 5 to 200 g / L, and in the case of a mixed acid of nitric acid and hydrofluoric acid, the concentration of nitric acid can be 5 to 200 g / L and the concentration of hydrofluoric acid can be 1 to 20 g / L, respectively. Since it is manufactured in coil units, the retention time can be defined as the time for the coil to be immersed in the above acid and remain for 1 m in the direction of the coil length, and is preferably 1 to 120 seconds.

[0042] Hereinafter, the present invention will be described in more detail through examples.

[0043] (Example)

[0044] In the present invention, as an example of a representative component in weight %, austenitic stainless steel coil base material of an inventive example and a comparative example having a composition and film index of Table 1 below based on the components of 0.02%C, 0.7%Si, 1.0%Mn, 0.3%Cu, 10%Ni, 16.1%Cr, 2.1%Mo, 0.01%Al was prepared in the thickness range of Table 2 below. The coil was immersed in a bath containing 50 g / L sulfuric acid in a continuous line for 30 seconds, washed with water, and then immediately immersed in a copper plating bath containing 100 g / L CuSO4·5H2O and 100 g / L H2SO4, and a current density of 15 A / dm 2A copper plating layer having a thickness as shown in Table 2 below was formed by applying the above, and the ratio of the average thickness of the copper plating layer to the austenitic stainless steel coil base material is shown.

[0045] The components of stainless steel in Table 1 below were measured using equipment commonly used in academia and industry, such as inductively coupled plasma (ICP) or spectrometers. Since the components of the plating layer are relatively thin compared to the stainless steel base material, they can be measured using energy dispersive spectroscopy attached to a scanning electron microscope or tunneling electron microscope. However, when measuring with energy dispersive spectroscopy, carbon and oxygen may affect the component contents due to contamination of the specimen, so they were excluded from the final results, and the elements coated for specimen observation were also excluded. The copper and nickel plating layers were calculated by extracting five random spots from the central layer in the thickness direction and taking the average of these.

[0046] After forming, peeling can be determined using various methods such as tension, Ericsson forming, and cupping. In the present invention, 15% uniaxial tension was used as an example. Afterwards, peeling from the stainless steel base material and copper plating layer was observed. Peeling is a commonly used concept that can be determined visually, but for convenience, it will be described specifically as 10x10mm. 2 It can be understood that the copper plating layer of the area is separated from the stainless steel base material by a distance of more than 1 mm.

[0047] Although it is difficult to quantify the scale of appearance evaluation method, in the present invention, the degree that is judged to be a generally acceptable range is considered as passing and is shown in Table 1 below.

[0048] 100x100 mm on the surface 2The area ratio of the copper plating layer is measured from the surface. The surface refers to the surface of the material observed in a direction perpendicular to the surface of the material. The location of the surface is the center in the width direction of the material. In the longitudinal direction, in the case of a coil, it can be measured at a position 1 m away from the end of the coil, but if there are many scratches, 1 to 10 m can be discarded. The area ratio can be analyzed after taking a picture with a conventional digital camera. The copper plating layer appears orange when taken from the surface with a digital camera, and the base material mainly appears as an achromatic color between white and gray, so the area ratio of the plating layer can be calculated after separating the two groups by color. If it is difficult to separate the two groups, use an objective lens of 5x or 10x on an optical microscope to obtain a 100x100 mm image. 2 After dividing the area into 100 equal areas and taking a picture, you can separate the two groups by color separation as above.

[0049] The thickness of STS, copper plating, and nickel plating can be measured by mirror-polishing the cross-section and observing it with an optical microscope or scanning electron microscope. Measurement of length using an optical microscope or scanning electron microscope can follow conventional methods.

[0050] Si content (wt. %)Al content (wt. %)Mn content (wt. %)Film indexInvention example 10.600.1121.100.75Invention example 20.700.0121.050.69Invention example 30.880.0031.150.77Invention example 40.350.0051.250.29Invention example 50.660.1400.811.16Invention example 60.120.0061.450.09Comparative example 11.220.0050.891.38Comparative example 21.320.0100.921.46Comparative example 30.650.1600.761.28Comparative example 40.770.1100.581.71Comparative example 50.750.0090.611.26

[0051]

[0052] Copper area ratio (%) Copper content (wt. %) Appearance Thickness of stainless steel (mm) Thickness of copper plating layer (mm) Thickness ratio Peeling after molding Invention Honorable mention 110095 Passed 0.610.0150.02 Good Invention Honorable mention 210076 Passed 0.750.0050.01 Good Invention Honorable mention 310098 Passed 0.380.0740.19 Good Invention Honorable mention 410098 Passed 0.650.0890.14 Good Invention Honorable mention 510077 Passed 0.990.0950.10 Good Invention Honorable mention 610099 Passed 1.210.0500.04 Good Invention Honorable mention 79595 Passed 0.620.0550.09 Good Invention Honorable mention 89188 Pass 0.65 0.060 0.09 Good Comparison Example 18595 Failed 0.55 0.088 0.16 Good Comparison Example 28899 Failed 0.77 0.066 0.09 Good Comparison Example 39455 Failed 0.65 0.02 20.03 Good Comparison Example 49344 Failed 0.71 0.01 50.02 Good Comparison Example 56080 Failed 0.62 0.180 0.29 Peeling Comparison Example 610095 Pass 0.61 0.150 0.25 Peeling Comparison Example 710094 Pass 0.41 0.088 0.21 Peeling Comparison Example 810099 Pass 0.74 0.21 10.29 Peeling Comparison Example 910091 Pass 0.95 0.25 0.26 Peeling Comparison Example 1010099 Pass 0.55 0.12 20.22 Peeling

[0053] Inventive Examples 1 to 8 in Table 1 satisfy the film index (Si+2Al) / Mn according to the Si content, Al content, and Mn content of 1.2 or less as suggested in the present invention. Inventive Examples 1 to 8 have an area ratio of the copper plating layer of 95% or more as shown in Table 2, and the copper content in the copper plating layer is 75% or more, and the appearance evaluation results are shown to be passed as shown in Fig. 1. On the other hand, Comparative Examples 1 to 5 have a film index exceeding 1.2, and the copper area ratio did not reach 95% as shown in Fig. 2, the copper content of the plating layer did not reach 75%, and the appearance evaluation results are shown to be failed. On the other hand, Inventive Examples 1 to 8 simultaneously satisfy the range of the present invention of 0.2 or less for the thickness ratio of the stainless steel and copper plating layer, and also have good peeling characteristics. On the other hand, Comparative Examples 6 to 10 can be seen that although the film index is satisfied, the thickness ratio is unsatisfactory, and peeling occurs.

[0054] Although exemplary embodiments of the present invention have been described above, the present invention is not limited thereto, and those skilled in the art will understand that various changes and modifications are possible within the scope and spirit of the claims set forth below.

Claims

1. Austenitic stainless steel coil base material; and Including a copper plating layer provided on the outer surface of the above-mentioned parent material, The average thickness of the copper plating layer is 1 ㎛ to 100 ㎛ or less, A copper-plated austenitic stainless steel coil, wherein the ratio of the average thickness of the copper plating layer to the austenitic stainless steel coil base material is 0.2 or less.

2. In claim 1, The above austenitic stainless steel coil base material is a copper-plated austenitic stainless steel coil having a film index expressed as (Si+2Al) / Mn of 1.2 or less. (Here, Si, Al, and Mn represent the content of each element) 3. In claim 1, A copper-plated austenitic stainless steel coil, wherein the composition of the above austenitic stainless steel coil base material contains, in wt%, C: 0.005 to 0.080%, Si: 0.1 to 1.0%, Mn: 0.1 to 1.5%, Cu: 0.05 to 0.5%, Ni: 8 to 13%, Cr: 16 to 20%, Mo: 0.05 to 2.5%, and Al: 0.001 to 0.2%.

4. In claim 1, 100x100mm on the surface 2 A copper-plated austenitic stainless steel coil, wherein the area ratio of the copper plating layer is 95% or more in area.

5. In claim 1, A copper-plated austenitic stainless steel coil, wherein the copper-plated layer contains copper in an amount of 75% or more by weight.

6. In claim 1, A copper-plated austenitic stainless steel coil further comprising a nickel plating layer between the austenitic stainless steel coil base material and the copper plating layer.

7. Step of preparing an austenitic stainless steel coil base material; and Immerse in a solution containing 10 g / L to 500 g / L of CuSO4·5H2O, 10 g / L to 500 g / L of H2SO4, and the remainder of water, at a pressure of 1 A / dm 2 Within 50A / dm 2 A method for manufacturing a copper-plated austenitic stainless steel coil, comprising: a step of electroplating copper by applying a current density of 1 to 150 seconds.

8. In claim 7, A method for manufacturing a copper-plated austenitic stainless steel coil, wherein the above austenitic stainless steel coil base material satisfies a film index expressed by (Si+2Al) / Mn of 1.2 or less. (Here, Si, Al, and Mn represent the content of each element) 9. In claim 7, A method for manufacturing a copper-plated austenitic stainless steel coil, wherein the composition of the austenitic stainless steel coil base material contains, in wt%, C: 0.005 to 0.080%, Si: 0.1 to 1.0%, Mn: 0.1 to 1.5%, Cu: 0.05 to 0.5%, Ni: 8 to 13%, Cr: 16 to 20%, Mo: 0.05 to 2.5%, and Al: 0.001 to 0.2%.

10. In claim 7, A method for manufacturing a copper-plated austenitic stainless steel coil, comprising a step of immersing in a mixed acid of sulfuric acid having a concentration of 5 g / L to 200 g / L or nitric acid and hydrofluoric acid having a concentration of 1 g / L to 20 g / L for 1 second to 120 seconds prior to copper plating.

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