Copper-nickel-silicon alloy with improved bendability and method for manufacturing the same

Abstract

To provide a copper-nickel-silicon alloy having improved bending workability while maintaining excellent strength and electric conductivity, and to provide a method for producing the same.SOLUTION: A copper-nickel-silicon alloy with improved bending workability, comprising 3 to 4.5 wt% of nickel (Ni), 0.7 to 1.0 wt% of silicon (Si), and a balance of copper (Cu) and inevitable impurities, based on the total weight of the copper-nickel-silicon alloy, wherein an area fraction of {100} <001> (Cube orientation) is 3% or more after a solution treatment process.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present application relates to a copper-nickel-silicon alloy having improved bending workability and a method for manufacturing the same, and more particularly to a copper-nickel-silicon alloy having improved bending workability while maintaining excellent strength and electrical conductivity, and a method for manufacturing the same. [Background technology]

[0002] The rapid development of the automotive, electrical, and electronic component industries has led to a demand for the development of high-performance components that realize miniaturization and high integration. Recently, materials for small electronic devices are required to be less than 0.1 mm thick due to the trend toward lighter, thinner, and smaller devices. However, even in this thin state, excellent bendability is required because severe bending processes approaching 180°, such as HEM (complete contact bending), are performed on materials of this thickness. If cracks occur during the process due to insufficient bendability, they can adversely affect product reliability, making them unsuitable for this application.

[0003] On the other hand, copper alloys have a better balance of strength and electrical conductivity than other metals and are widely used as materials for contact points in electronic products. As mentioned above, with the trend toward miniaturization of electronic components, copper alloys used in these components are required to have not only excellent strength and electrical conductivity but also excellent formability.

[0004] However, strengthening processes such as precipitation strengthening, solid solution strengthening, dispersion strengthening, and work hardening that improve the strength of copper alloys can reduce the bendability of the alloy. In other words, strength and bendability are mutually exclusive properties, and increasing one property reduces the other. Therefore, there is a limit to how much the strength and bendability of copper alloys can be improved simultaneously.

[0005] Therefore, in order to develop high-performance parts that realize miniaturization and high integration, it is necessary to design copper alloys that have excellent strength and electrical conductivity as well as improved bendability, and to design manufacturing processes for the same.

[0006] As background art of the present application, Patent Document 1 discloses a copper alloy material for automobiles and electric and electronic parts, and a method for producing the same. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent No. 10-1627696 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present application is to provide a copper-nickel-silicon alloy having improved bending workability by improving the bending workability of a copper-nickel-silicon alloy system, which has the best combination of strength and electrical conductivity among copper alloys but lacks bending workability.

[0009] Another object of the present invention is to provide a method for producing a copper-nickel-silicon alloy having improved bending workability while maintaining excellent strength and electrical conductivity.

[0010] The objects of the present application are not limited to those mentioned above, and other objects not mentioned will be clearly understood from the detailed description. [Means for solving the problem]

[0011] According to one aspect, the copper-nickel-silicon alloy contains 3 to 4.5 wt. % nickel (Ni), 0.7 to 1.0 wt. % silicon (Si), and the balance copper (Cu) and unavoidable impurities, based on the total weight of the copper-nickel-silicon alloy, and after a solution treatment step, has a {100} <001> A copper-nickel-silicon alloy having an area fraction of (Cube orientation) of 3% or more and improved bending workability is provided.

[0012] According to one embodiment, after the solution treatment step, the {112} <111> The area fraction of (Copper orientation) can be 11% or less.

[0013] According to one embodiment, after the intermediate heat treatment step, the area fraction of the recrystallized structure is 5% to 65%, of which {100} <001> The area fraction of (Cube orientation) can be 15% or more.

[0014] According to one embodiment, a cube texture may be generated around Ni2Si particles during the intermediate heat treatment process.

[0015] According to one embodiment, the copper-nickel-silicon alloy having improved bendability of the present invention may have Ni2Si particles of 0.5 μm to 2.0 μm distributed therein.

[0016] According to one embodiment, the copper-nickel-silicon alloy having improved bendability of the present application may have a 90° bend test performance in which the ratio R / t of the bend radius R to the plate thickness t is 0.25 or more.

[0017] According to one embodiment, the copper-nickel-silicon alloy having improved bending workability of the present invention may be free from cracks when a thin plate having a thickness of 10 μm to 500 μm is bent at a ratio R / t of the bending radius R to the plate thickness t of 0.25 to 2.0 and is bent at a 90° angle in the vertical and horizontal directions of the rolling direction for complete contact.

[0018] According to one embodiment, the copper-nickel-silicon alloy having improved bendability of the present invention may have a tensile strength of 800 MPa or more and an electrical conductivity of 30% IACS or more.

[0019] According to one embodiment, the copper-nickel-silicon alloy having improved bendability of the present invention may have an average Taylor factor of 3.2 or less.

[0020] According to one embodiment, the present copper-nickel-silicon alloy with improved bendability may be in the form of a sheet or plate.

[0021] According to another aspect, there is provided a method for producing a copper-nickel-silicon alloy with improved bendability, the method comprising the steps of: i) casting a copper-nickel-silicon alloy containing 3 to 4.5 wt. % of nickel (Ni), 0.7 to 1.0 wt. % of silicon (Si), and the balance being copper (Cu) and unavoidable impurities, based on the total weight of the copper-nickel-silicon alloy; ii) rolling the cast copper-nickel-silicon alloy; iii) subjecting the rolled copper-nickel-silicon alloy to an intermediate heat treatment at 600°C to 800°C for a period exceeding 0 minutes but not exceeding 30 minutes; iv) rolling the intermediate heat-treated copper-nickel-silicon alloy; and v) solution treating the rolled copper-nickel-silicon alloy.

[0022] According to one embodiment, the method for producing a copper-nickel-silicon alloy with improved bendability of the present application may further include the steps of: vi) cold rolling the solution-treated copper-nickel-silicon alloy; and vii) precipitation treating the cold-rolled copper-nickel-silicon alloy.

[0023] According to one embodiment, in the method for producing a copper-nickel-silicon alloy having improved bendability of the present invention, the step v) of solution treatment may be a solution treatment at 850°C or higher and lower than 950°C for more than 0 minutes and not more than 30 minutes. [Effects of the Invention]

[0024] According to one embodiment, the present copper-nickel-silicon alloy may contain a texture that is beneficial to formability, resulting in improved bendability.

[0025] According to one embodiment, in a workpiece such as a sheet material including the copper-nickel-silicon alloy of the present application, the area of ​​the cube structure does not decrease even when cold-rolled, and cube-oriented crystal grains are additionally generated, thereby improving bending workability.

[0026] According to one embodiment, the method for producing a copper-nickel-silicon alloy of the present application includes an intermediate heat treatment step during the production process, which generates a texture that can improve bending workability, thereby making it possible to efficiently produce a copper-nickel-silicon alloy with excellent bending workability.

[0027] According to one embodiment, the method for manufacturing a copper-nickel-silicon alloy of the present application may control the generation of texture to improve the bending workability of the copper-nickel-silicon alloy while preventing a decrease in tensile strength and electrical conductivity. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a graph showing the manufacturing process for producing a typical copper-nickel-silicon alloy, and an image showing the change in texture due to the manufacturing process. [Figure 2] 1 is a graph showing a manufacturing process for controlling the texture of a copper-nickel-silicon alloy according to an embodiment of the present application, and an image showing the change in texture due to the manufacturing process. [Figure 3] 3(a) is a graph showing a manufacturing process of a copper-nickel-silicon alloy without intermediate heat treatment according to a comparative example of the present application (FIG. 3(a)), and a manufacturing process for controlling texture by intermediate heat treatment according to an example of the present application (FIG. 3(b)). [Figure 4] 1 is an image showing the change in texture depending on the temperature and time conditions of intermediate heat treatment of a copper-nickel-silicon alloy produced according to an embodiment of the present application. [Figure 5] 1 is an image showing the texture of a copper-nickel-silicon alloy after intermediate heat treatment produced according to Example 1 of the present application. [Figure 6] 1 is an image showing the change in texture depending on the temperature and time conditions of solution treatment of a copper-nickel-silicon alloy produced in Example 1 of the present application. [Figure 7] 1 is an image showing the texture of a copper-nickel-silicon alloy after solution treatment produced by Comparative Example 1 and Example 1 of the present application. [Figure 8]8A and 8B show images and graphs illustrating the IPF ((a) and (b) of FIG. 8), texture ((c) and (d) of FIG. 8), ODF maps ((e) and (f) of FIG. 8), texture area fraction ((g) and (h) of FIG. 8), grain size ((i) and (j) of FIG. 8), and particle distribution ((k) and (l) of FIG. 8) of the copper sheet metal materials produced according to Comparative Example 2 and Example 2 of the present application. [Figure 9] FIG. 1 is a diagram illustrating a bending test method for a copper-nickel-silicon alloy according to an embodiment of the present application. [Figure 10] 1 shows FESEM images of precipitation-hardened copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2 of the present application after bending experiments, and images showing the distribution of IPF, KAM, and texture. [Figure 11] FIG. 2 is a diagram showing the results of bend formability and tensile tests of copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2 of the present application. [Figure 12] 1 is a graph showing the Taylor modulus and GOS (grain orientation spread) in the shear band after bending copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2 of the present application. [Figure 13] 1 is a graph showing FESEM images and particle distributions of copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2 of the present application after casting and hot rolling at 950° C. for 2 hours. [Figure 14] 1 is an image showing the texture around particles of copper-nickel-silicon alloys produced by Comparative Example 2 and Example 2 of the present application after cold rolling at a rolling reduction of 85%. [Figure 15] 15(a) and (b) show the (111) pole figures of the copper-nickel-silicon alloys produced by Comparative Example 2 and Example 2 of the present application after cold rolling at reductions of 85% and 90%, respectively. FIG. 15(c) shows the texture in the (111) pole figure. FIG. 15(d) to (g) are images showing the results of IQ, IPF, texture, and KAM after a rolling reduction of 85%. [Figure 16]1 is an image showing the results of IQ, IPF, texture, and KAM after cold rolling and intermediate heat treatment of copper-nickel-silicon alloys produced by Comparative Example 2 and Example 2 of the present application. [Figure 17] 1 is an image showing the results of structural analysis of the recrystallized regions of the grain system and shear band regions after intermediate heat treatment of copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2 of the present application. [Figure 18] 1 is an image showing the change in microstructure of copper-nickel-silicon alloys according to the process steps produced by Comparative Example 2 and Example 2 of the present application. [Figure 19] 1 is an image showing the results of analyzing the recrystallized structure after one minute of solution treatment of the copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2 of the present application. [Figure 20] 1 is a graph showing IPF and ODF images and texture area fractions obtained by analyzing the structure of fully recrystallized copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2 of the present application after solution treatment. DETAILED DESCRIPTION OF THE INVENTION

[0029] The objects, advantages, and features of the present application will become more apparent from the following detailed description and examples taken in conjunction with the accompanying tables and drawings.

[0030] Prior to that, the terms and words used in this specification and claims should not be interpreted and evaluated in accordance with their ordinary dictionary meanings, but should be interpreted in accordance with the meanings and concepts consistent with the technical ideas of this disclosure, based on the principle that an inventor may appropriately define the concepts of terms in order to best explain his or her invention.

[0031] The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the present disclosure. The singular expressions include the plural expressions unless the context clearly indicates otherwise.

[0032] As used herein, the terms "comprise" or "have" and the like are intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof described above in the specification, but should be understood not to preclude the presence or possible addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0033] In this specification, when a part "comprises" a certain element, this does not mean that it excludes other elements, but that it may further include other elements, unless otherwise specified to the contrary.

[0034] The present application will be described in more detail with reference to the following examples. However, the scope of the present application is not limited to the following examples, and includes modifications of the technical ideas equivalent thereto.

[0035] Hereinafter, the copper-nickel-silicon alloy having improved bending workability and the manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying tables and drawings.

[0036] According to one aspect of the present application, the copper-nickel-silicon alloy having improved bendability contains 3 to 4.5 wt. % of nickel (Ni), 0.7 to 1.0 wt. % of silicon (Si), and the balance of copper (Cu) and unavoidable impurities, based on the total weight of the copper-nickel-silicon alloy. After a solution treatment process, the copper-nickel-silicon alloy has a {100} <001> The area fraction of (Cube orientation) is 3% or more.

[0037] Copper-nickel-silicon alloys are a typical precipitation-hardened copper alloy, characterized by the ability to improve strength and electrical conductivity by precipitating fine nickel-silicon (Ni-Si) intermetallic compound particles such as NiSi in the copper matrix. The inventors have confirmed that introducing an intermediate heat treatment process during the cold rolling process prior to solution treatment can generate a cube texture and improve bending workability.

[0038] Figure 1 is a graph showing a manufacturing process for producing a typical copper-nickel-silicon alloy, and an image showing the change in texture due to the manufacturing process. Figure 2 is a graph showing a manufacturing process for controlling the texture of a copper-nickel-silicon alloy according to one embodiment of the present application, and an image showing the change in texture due to the manufacturing process.

[0039] 1 and 2, the present application introduces an intermediate heat treatment process as a process control for thermomechanical treatment, thereby generating a texture with excellent formability and improving the bending workability of a copper-nickel-silicon alloy without reducing its strength. Generally, cold rolling, which is an essential process for producing copper alloy sheets for connectors, significantly reduces the area fraction of the cube texture of the copper alloy. However, adding an intermediate heat treatment process during the rolling process can suppress the reduction in the area fraction of the cube texture of the alloy due to rolling and can even generate additional cube-oriented grains.

[0040] Nickel (Ni) is a solution hardening element known to improve the strength and electrical conductivity of copper alloys by forming Ni-Si precipitates. However, this application has been discovered for the first time that nickel can form Ni2Si particles and generate a cube texture around these particles. While not limited to this, if the nickel (Ni) content is less than 3 wt%, this effect may not be sufficient. However, excessive nickel may reduce electrical conductivity or reduce bendability due to the formation of coarse precipitates, so it is best not to exceed 4.5 wt%.

[0041] Silicon (Si) is an element necessary for the formation of Ni-Si-based precipitates, which are compounds primarily composed of Ni2Si. Neither Ni nor Si in the alloy becomes precipitated by aging treatment; rather, some of it exists in a solid solution state in the matrix. While dissolved Ni and Si improve the strength of copper alloys, this effect is less than that of their precipitated state and can cause a decrease in electrical conductivity. Therefore, the silicon (Si) content of the copper-nickel-silicon alloy should be 0.7 to 1 wt.% based on the total weight.

[0042] The strength of copper-nickel-silicon alloys can be increased by increasing the amount of nickel and silicon added, but the increase in strength may saturate once a certain amount of addition is exceeded.

[0043]

[0023] Including, but not limited to, the {100} of copper-nickel-silicon alloy after the solution treatment process. <001> An area fraction of (Cube orientation) of 3% or more may be suitable for improving bending workability, 5% or more may be more suitable, and 10% or more may be even more suitable.

[0044] After the solution treatment process, the {112} <111> An area fraction of {112} (Copper orientation) of 11% or less may be suitable for improving bending workability, 10% or less may be more suitable, 9% or less may be even more suitable, and 8% or less may be even more suitable. <111> The area fraction of (Copper orientation) can decrease with increasing cube texture.

[0045] Although not limited thereto, after the solution treatment process, the area fraction of the recrystallized structure is 5% to 65%, of which {100} <001> An area fraction of 15% or more (Cube orientation) may be more suitable for improving bending workability.

[0046] Although not limited thereto, Ni2Si particles of 0.5 μm to 2.0 μm are distributed in the copper-nickel-silicon alloy with improved bendability of the present invention, and a cube texture may be generated around the Ni2Si particles during the intermediate heat treatment process.

[0047] Although not limited thereto, the copper-nickel-silicon alloy with improved bending workability of the present application has a 90° bending test performance in which the ratio R / t of the bending radius R to the plate thickness t is 0.25 or more, and has excellent bending workability.

[0048] Although not limited thereto, the copper-nickel-silicon alloy having improved bending workability exhibits excellent bending workability without cracking when a thin plate of 10 μm to 500 μm is bent at a ratio R / t of the bending radius R to the plate thickness t of 0.25 to 2.0 and is bent at 90 degrees in the vertical and horizontal directions of the rolling direction to achieve complete contact.

[0049] The copper-nickel-silicon alloy with improved bendability may have, but is not limited to, a tensile strength of 800 MPa or more and an electrical conductivity of 30% IACS (International Annealed Copper Standard) or more. The copper-nickel-silicon alloy is a representative precipitation-hardened copper alloy, characterized by the fact that it can improve tensile strength and electrical conductivity by precipitating fine nickel-silicon (Ni-Si)-based intermetallic compound particles such as NiSi in the copper matrix. The copper-nickel-silicon alloy according to the present application can maintain excellent strength and electrical conductivity while improving bendability.

[0050] Although not limited thereto, the copper-nickel-silicon alloy having improved bendability may have an average Taylor coefficient of 3.2 or less, and more preferably 3.0 or less.

[0051] The copper-nickel-silicon alloy may be in the form of, but is not limited to, a sheet or plate. The copper alloy sheet or plate according to the present application has improved bending workability, excellent strength and electrical conductivity, and is applicable to lead frames, connectors, terminal materials for electrical and electronic devices, connectors and terminal materials for automobiles, relays, switches, etc.

[0052] Recently, development of ultra-miniaturized male terminals for connectors has been progressing, with thicknesses of 0.64t or less. As connector thickness decreases, high-strength copper alloy sheet materials are required. While conventional processes can maintain a balance between strength and electrical conductivity at thicknesses of 1t or less, there is a problem in that it is difficult to ensure bending workability. This application solves this problem.

[0053] According to another aspect, the present invention provides a method for producing a copper-nickel-silicon alloy with improved bendability, comprising the steps of: i) casting a copper-nickel-silicon alloy containing 3 to 4.5 wt. % of nickel (Ni), 0.7 to 1.0 wt. % of silicon (Si), and the remainder being copper (Cu) and unavoidable impurities, based on the total weight of the copper-nickel-silicon alloy; ii) rolling the cast copper-nickel-silicon alloy; iii) subjecting the rolled copper-nickel-silicon alloy to an intermediate heat treatment at 600°C to 800°C for a period exceeding 0 minutes up to 30 minutes; iv) rolling the intermediate heat-treated copper-nickel-silicon alloy; and v) solution treating the rolled copper-nickel-silicon alloy.

[0054] Although not limited thereto, the step ii) of rolling may include a step of hot rolling the cast alloy by maintaining the alloy at 900 to 1,000°C for 30 minutes to 4 hours, and then performing a first cold rolling at a cold reduction of 80% or more after the hot rolling. Although not limited thereto, a first cold rolling at a cold reduction of 80% to 99.99% may be more suitable.

[0055] Although not limited thereto, if the intermediate heat treatment process in step iii) is performed at a temperature below 600°C, the effect of the intermediate heat treatment may be negligible, and if it exceeds 800°C, the alloy temperature may rise excessively, reducing the formation of cube texture. Although not limited thereto, the intermediate heat treatment in step iii) is preferably performed for 30 seconds to 30 minutes depending on the thickness of the sheet material. In step iii), intermediate heat treatment for more than 0 to 30 minutes may be suitable for the formation of cube texture, intermediate heat treatment for 30 seconds to 30 minutes may be more suitable, and intermediate heat treatment for 5 to 30 minutes may be even more suitable.

[0056] Although not limited thereto, the step of rolling the intermediate heat-treated copper-nickel-silicon alloy in iv) may include a step of performing a second cold rolling at a cold reduction of 30% or more. Although not limited thereto, a second cold rolling at a cold reduction of 30% to 50% may be more suitable.

[0057] Although not limited thereto, the solution treatment in step v) may be performed at 850°C to less than 950°C for more than 0 to 30 minutes. If the solution treatment in step v) is performed below 850°C, the solution treatment time becomes long, which may result in a rapid decrease in productivity, while if it is performed at 950°C or higher, the growth of cube texture after recrystallization may be insufficient. Although not limited thereto, the solution treatment in step v) may be performed for more than 0 to 30 minutes depending on the thickness of the sheet material, more preferably for more than 30 seconds to 30 minutes, and even more preferably for 3 to 30 minutes.

[0058] Although not limited thereto, the method for producing a copper-nickel-silicon alloy with improved bendability of the present application may further include the steps of: vi) cold-rolling the solution-treated copper-nickel-silicon alloy; and vii) precipitation-treating the cold-rolled copper-nickel-silicon alloy.

[0059] Although not limited thereto, in the cold rolling step vi), cold rolling at a cold reduction of 75% or less may be suitable for improving the bending workability of the alloy, cold rolling at a cold reduction of 50% or less may be more suitable, cold rolling at a cold reduction of 40% or less may be even more suitable, and cold rolling at a cold reduction of 30% or less may be even more suitable.

[0060] Although not limited thereto, in the precipitation treatment step vii), precipitation at 400°C to 600°C for 30 minutes to 10 hours may be suitable for improving the bendability of the alloy, precipitation for 30 minutes to 5 hours may be more suitable, precipitation for 30 minutes to 3 hours may be even more suitable, and precipitation for 30 minutes to 2 hours may be even more suitable.

[0061] The present invention will now be described in more detail with reference to examples.

[0062] Example The copper-nickel-silicon alloys of Comparative Examples 1 and 2 and Examples 1 and 2 according to the present invention have the compositions shown in Table 2 below, and were manufactured by casting, hot rolling, first cold rolling, solution treatment, second cold rolling, and precipitation treatment. However, Examples 1 and 2 include an intermediate heat treatment step during the first cold rolling, while Comparative Examples 1 and 2 do not include the intermediate heat treatment step.

[0063] [Table 1]

[0064] In the case of copper-nickel-silicon alloys, textures mainly called Cube orientation, Brass orientation, Copper orientation, and S orientation are formed, and corresponding crystal planes exist, as shown in Table 2 below.

[0065] The formation of these textures differs depending on the conditions of intermediate heat treatment and solution treatment even for the same crystal system. In the case of materials such as plate materials by rolling, the texture is expressed by plane and direction, but the plane is represented by {ABC} and the direction is <def>It is expressed as:

[0066] The method of expressing crystal orientation in this specification is to use a rectangular coordinate system in which the rolling direction RD of the material is the X axis, the sheet width direction TD is the Y axis, and the normal direction ND of the rolling is the Z axis, and each region in the material is expressed by the index {hkl} of the crystal plane perpendicular to the Z axis and the index {hkl} of the crystal direction parallel to the X axis. <uvw>Using {hkl} <uvw>According to the above notation, each orientation is expressed as shown in Table 2 below. The area fraction of each texture is defined based on an error range of 15°.

[0067] [Table 2]

[0068] As mentioned above, the texture of a typical copper-nickel-silicon alloy is composed of a considerable number of orientation factors. If the composition ratio of these crystal planes changes, the behavior of the texture of the material, such as sheet metal, changes, and workability such as bending workability also changes.

[0069] Experimental example 1. Evaluation of properties of copper-nickel-silicon alloys according to intermediate heat treatment and solution treatment conditions 1-1. Area fraction (%) of texture in copper-nickel-silicon alloys after intermediate heat treatment and solution treatment In order to confirm the changes in the area fraction (%) of Cube, Brass, Copper, and S textures in the area fraction (%) of the textures after the intermediate heat treatment and solution treatment of the copper-nickel-silicon alloy according to the present invention, copper-nickel-silicon alloys having the compositions shown in Table 1 above were produced, and the evaluation results are shown in Table 3.

[0070] 3 is a graph showing a manufacturing process of a copper-nickel-silicon alloy without intermediate heat treatment according to a comparative example of the present application (FIG. 3(a)), and a manufacturing process for controlling texture by intermediate heat treatment according to an embodiment of the present application (FIG. 3(b)). Referring to FIG. 3, for comparative examples 1 and 2 and examples 1 and 2, the alloy components according to the composition in Table 1 were heated, melted, and cast, and then hot-rolled at 950°C for 2 hours with a cross-sectional reduction of 50% and then cold-rolled with a cross-sectional reduction of 90%.

[0071] In Examples 1 and 2, which included an intermediate heat treatment step, the copper-nickel-silicon alloy was subjected to an intermediate heat treatment at 700°C for 15 minutes after 85% rolling in the rolling process with a total reduction of 90%. After the cold rolling including the intermediate heat treatment, the alloy was subjected to a solution treatment at 900°C and water quenching. After the solution treatment, oxide scale on the surface of the 100 μm-thick plate material was removed by grinding with a grinder. The thickness after grinding was 80 μm. Next, the alloy was cold rolled at a cross-sectional reduction of 30% and aged at 500°C for 30 minutes.

[0072] In the case of Comparative Example 1 (Cu-3.0Ni-0.7Si), no intermediate heat treatment step was performed, and solution treatment was performed for 3 minutes at 900°C. After solution treatment, the area fraction (%) of the texture was shown to be 1.2% for the cube texture, which was lower than the area fractions of the brass, copper, and S textures.

[0073] In the case of Comparative Example 2 (Cu-4.5Ni-1.0Si), no intermediate heat treatment step was performed, and solution treatment was performed for 10 minutes at 950°C. After solution treatment, the area fraction of the texture was shown to be 2.1%, which was lower than the area fractions of the brass, copper, and S textures.

[0074] Therefore, in Comparative Examples 1 and 2, which did not undergo the intermediate heat treatment step, the area fraction of the cube texture was lower than in Examples 1 and 2.

[0075] In the case of Example 1 (Cu-3.0Ni-0.7Si), solution treatments were performed at 600°C, 700°C, and 800°C for 5 minutes. After the intermediate heat treatment, solution treatments were performed at 850°C, 900°C, and 950°C for 3 minutes. After solution treatment, the area fraction of the cube texture was the highest at 11.0% when the intermediate heat treatment was performed at 800°C for 5 minutes followed by solution treatment at 900°C for 3 minutes. The area fractions of the brass, copper, and S textures were 8.5%, 7.8%, and 14.3%, respectively.

[0076] In the case of Example 2 (Cu-4.5Ni-1.0Si), the intermediate heat treatment was performed at temperatures of 700°C and 800°C for 15 minutes and 5 minutes, respectively. After the intermediate heat treatment, solution treatment was performed at 950°C and 900°C for 10 minutes and 3 minutes, respectively. When the intermediate heat treatment was performed at 700°C for 15 minutes followed by solution treatment at 950°C for 10 minutes, the area fraction of the cube texture was the highest at 15.6%, and the area fractions of the brass, copper, and S textures were 12.1%, 5.2%, and 16.2%, respectively.

[0077] [Table 3]

[0078] 1-2. Texture change of copper-nickel-silicon alloy due to intermediate heat treatment Figure 4 is an image showing the change in texture of a copper-nickel-silicon alloy produced according to Example 1 of the present application depending on the temperature and time conditions of the solution treatment. Figure 4 shows the change in texture depending on the intermediate heat treatment conditions of Example 1. When intermediate heat treatment was performed for 5 minutes at 600°C, 5 minutes at 70°C, and 5 minutes at 800°C, the recrystallization rates were 5%, 23%, and 64%, respectively. It was found that the intermediate heat treatment process recrystallizes a portion of the structure of the copper-nickel-silicon alloy, and intermediate heat treatment for 5 minutes at 800°C resulted in the highest recrystallization rate of 64%, making it more suitable for excellent bending workability.

[0079] Figure 5 is an image showing the texture of the copper-nickel-silicon alloy after intermediate heat treatment produced in Example 1. Figure 5 shows that when intermediate heat treatment was performed at 800°C for 5 minutes in Example 1, the area fraction of cube texture in the recrystallized structure was 17.4%. Therefore, some cube texture is generated during the intermediate heat treatment, and these can grow into coarse cube grains during the subsequent solution treatment process.

[0080] Figure 6 is an image showing the change in texture depending on the temperature and time conditions of solution treatment for the copper-nickel-silicon alloy produced in Example 1 of the present application. From Figure 6, it can be seen that all structures are recrystallized by solution treatment, and the most abundant cube texture is produced when solution treatment is performed at 900°C for 3 minutes. When solution treatment is performed at 950°C for 3 minutes, the texture becomes more widespread, which may not be suitable.

[0081] 7 is an image showing the texture of the copper-nickel-silicon alloys after solution treatment produced by Comparative Example 1 and Example 1 of the present application. From the OFF map in FIG. 7, it can be seen that when Comparative Example 1 and Example 1 are solution treated at 900°C for 3 minutes, no cube texture is observed in Comparative Example 1, but a considerable amount of cube texture is observed in Example 1.

[0082] 1-3. Evaluation of mechanical properties of copper-nickel-silicon alloys depending on whether intermediate heat treatment is performed or not The hardness, tensile strength, ductility, and electrical conductivity properties of the copper-nickel-silicon alloy of the present invention as a function of the intermediate heat treatment and solution treatment conditions are shown in Table 4 below.

[0083] According to Table 4 below, after solution treatment, the ductility of Comparative Example 2 and Example 2 was 13.1% and 12.9%, respectively, with no significant difference. The hardness of Comparative Example 2 and Example 2 was 79.2 Hv and 79.9 Hv, respectively, which were higher than those of Example 2 and Comparative Example 2. The tensile strength and electrical conductivity of Example 2 were 375.2 MPa and 19.2%, respectively, which were higher than those of Comparative Example 2.

[0084] After the thermomechanical treatment, the hardness of Comparative Example 2 and Example 2 was 224.9 Hv and 216.8 Hv, respectively, with no significant difference, the tensile strength was 811.8 MPa and 804.7 MPa, respectively, with no significant difference, and the electrical conductivity was 32.8% IACS and 31.3% IACS, with no significant difference. The ductility of Example 2 was 4.1%, which was higher than that of Comparative Example 2.

[0085] [Table 4]

[0086] Therefore, it was confirmed that the hardness, tensile strength, ductility, and electrical conductivity of the copper-nickel-silicon alloy may not be reduced even if the alloy is subjected to intermediate heat treatment.

[0087] 8 shows the macroscopic microstructure and texture analysis of two specimens to analyze the cause of the difference in bending workability between the copper sheet metal materials manufactured according to Comparative Example 2 and Example 2. According to (a) to (h) of FIG. 8, after precipitation hardening (aging), about 2% of Cube-oriented grains were observed in the copper-nickel-silicon alloy of Comparative Example 2. In contrast, after precipitation hardening, a high proportion of Cube-oriented grains, about 14% or more, was observed in the copper-nickel-silicon alloy of Example 2.

[0088] 8(g) and 8(h), the copper-nickel-silicon alloy of Comparative Example 2 was primarily composed of crystal grains of S, Copper, and Brass orientations, accounting for area fractions of approximately 36%, 14%, and 10%, respectively, for a total area fraction of S, Copper, and Brass orientations of 60%. The copper-nickel-silicon alloy of Example 2 had smaller area fractions of S and Copper orientation crystal grains, approximately 33% and 9%, compared to the alloy of Comparative Example 2, but had a higher area fraction of Brass orientation crystal grains, accounting for approximately 15%. The total area fraction of S, Copper, and Brass orientations of the alloy of Example 2 was 60%.

[0089] In conclusion, there was no significant difference in the overall area fraction of the rolled textures (S, Copper, Brass) of the copper-nickel-silicon alloys produced by Comparative Example 2 and Example 2, but the cube-oriented grains in Example 2 were approximately 7 times higher than those in Comparative Example 2. It was analyzed that this cube texture improved the bending workability of the alloy by limiting the formation of shear bands during bending.

[0090] Figure 8 (i) to (l) show the size and distribution of particles dispersed in the crystal grains and matrix of the copper-nickel-silicon alloys produced by Comparative Example 2 and Example 2. The crystal grain sizes of the copper-nickel-silicon alloys produced by Comparative Example 2 and Example 2 were 19.7 μm and 19.6 μm, respectively, with little difference. Furthermore, the average particle sizes of the copper-nickel-silicon alloys were also nearly the same, at 0.83 μm and 0.81 μm, respectively. Therefore, the difference in bendability between the two copper-nickel-silicon alloys may be due to differences in texture rather than the size and distribution of the crystal grains or particles.

[0091] "Reinforcing phase" means a component within an alloy that increases its strength.

[0092] The copper-nickel-silicon alloy of Example 2 had superior bending workability compared to Comparative Example 2, which was analyzed to be due to the high area ratio of Cube texture, which is known to effectively improve the bending performance of face-centered cubic (FCC) alloys.

[0093] The comparable strength and electrical conductivity of the two alloys is believed to be due to the similar morphologies (size, distribution, and potential density of strengthening phases) of the two specimens after solution treatment due to the same precipitation and work-hardening processes.

[0094] FIG. 9 is a diagram schematically illustrating a bending experiment method for a copper-nickel-silicon alloy according to one embodiment of the present application.

[0095] In this application, the bending experiment was carried out using the copper-nickel-silicon alloy bending method shown in FIG.

[0096] 10 shows FESEM images, IPF, KAM, and texture distribution of the precipitation-hardened copper-nickel-silicon alloys produced in Comparative Example 2 and Example 2 of the present application after bending tests. Referring to FIG. 10, in order to analyze the effect of the texture on bending workability of the copper-nickel-silicon alloys produced in Comparative Example 2 and Example 2 of the present application, the texture in the transverse direction (TD) of the bent alloy sheets was examined after bending tests under the condition of R / t = 2.0.

[0097] As shown in Figure 10(a), shear bands were clearly observed after bending in the alloy of Comparative Example 2. Although strain concentrations were observed around the grains and in the grain system, greater strain energy was observed within the shear bands. Therefore, it can be predicted that cracking due to bending occurred in the shear bands rather than in the grains or grain system. The shear bands were shown to penetrate the copper and S-oriented grains. In contrast, no clear shear bands were observed in the alloy of Example 2 after bending, and it showed significantly less surface irregularities than the alloy of Comparative Example 2.

[0098] 10(f), although large shear bands and potential strain concentration areas were observed in the alloy of Example 2, the strain was smaller than that of the shear bands in the alloy of Comparative Example 2. It was analyzed that these strain concentration areas were generated along various textures such as Cube, Copper, and S. In conclusion, it was determined that the alloy of Example 2 had better bending workability because the generation of shear bands during bending was suppressed compared to the alloy of Comparative Example 2, and it was determined that the texture of the alloy had a significant effect on this.

[0099] 11 shows the results of bending workability and tensile tests of the copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2. As shown in FIG. 11(a), the copper-nickel-silicon alloy of Comparative Example 2 developed microcracks after W-bending (90° bending test) under the condition of R / t=1.5, and completely broke when bent under the condition of R / t=1.0.

[0100] 11(a), no cracks were observed on the surface of the copper-nickel-silicon alloy of Example 2 even after a bending test under the condition of R / t = 0.25. Therefore, the copper-nickel-silicon alloy of Example 2, which was produced using a process including an intermediate heat treatment, had superior bending workability compared to the copper-nickel-silicon alloy of Comparative Example 2, which was produced without an intermediate heat treatment. Tensile test results showed that there was almost no difference in strength and elongation after solution treatment and final thermo-mechanical treatment between Comparative Example 2 and Example 2.

[0101] FIG. 11(b) shows the results of tensile tests on the copper-nickel-silicon alloys of Comparative Example 2 and Example 2 after solution treatment and precipitation hardening.

[0102] According to FIG. 11 and Table 4, the copper-nickel-silicon alloy of Example 2, which was produced by a process including an intermediate heat treatment step, exhibited strength, electrical conductivity, and ductility comparable to those of the alloy of Comparative Example 2, which was produced without an intermediate heat treatment step, but exhibited superior bend formability.

[0103] The results of the structural analysis of the copper-nickel-silicon alloy revealed that the texture of the alloy has a direct effect on the formation of shear bands during bending, and the formation of these shear bands determines the bending workability of the alloy sheet. In order to quantitatively analyze the texture formed in the copper-nickel-silicon alloy of the present invention during bending, we attempted to quantitatively analyze the texture of the copper-nickel-silicon alloy.

[0104] FIG. 12 is a graph showing the Taylor modulus and GOS in the shear band after bending of copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2 of the present application.

[0105] FIG. 12(a) shows the results of calculating the Taylor coefficients at regular intervals from the surface of the alloy sheet along the shear band, assuming that the strain concentration region of the copper-nickel-silicon alloys of Comparative Example 2 and Example 2 analyzed in FIG. 10 is a shear band.

[0106] The average Taylor coefficient measured on the shear band of the copper-nickel-silicon alloy of Comparative Example 2 was 3.66, which was even higher than the average Taylor coefficient of 3.09 on the shear band of the copper-nickel-silicon alloy of Example 2. This means that the microstructure of the copper-nickel-silicon alloy of Comparative Example 2 can relatively easily generate shear bands during bending, and cracks due to bending occur more easily.

[0107] The microstructure of the copper-nickel-silicon alloy of Example 2 is such that the formation of shear bands is relatively suppressed due to uniform strain during bending, and therefore cracks occur less frequently than in the copper-nickel-silicon alloy of Comparative Example 2. This is likely due to the formation of a large amount of cube texture, which has the lowest Taylor coefficient among textures, in the copper-nickel-silicon alloy of Example 2, which is expected to improve bending workability.

[0108] Figure 12(b) compares the average Taylor coefficient and GOS values ​​of all grains after bending the copper-nickel-silicon alloys of Comparative Example 2 and Example 2 shown in Figure 10. Here, the GOS value represents the average misorientation angle of each grain, and a higher value indicates more strain induced in the grain. Figure 12(b) shows that the higher the Taylor coefficient of a grain, the higher the strain energy accumulated during bending. Consequently, the greater the cube texture, which has a low Taylor coefficient of 2.5 or less, the more effectively strain concentration due to bending can be suppressed. This means that the copper-nickel-silicon alloy of Example 2, which has a high cube texture, can effectively suppress the formation of shear bands during bending.

[0109] Analysis of the texture of copper-nickel-silicon alloys revealed that intermediate heat treatment plays an important role in increasing the proportion of Cube texture, which is key to improving the bendability of copper-nickel-silicon alloys. Therefore, to understand the mechanism by which intermediate heat treatment can improve the area fraction of the Cube texture in copper-nickel-silicon alloys, we investigated the changes in the texture of copper-nickel-silicon alloys at each process step in Example 2. First, we observed the microstructure of copper-nickel-silicon alloys after casting and hot rolling.

[0110] 13 is a graph showing FESEM images and particle distribution of the copper-nickel-silicon alloys of Comparative Example 2 and Example 2 after casting and hot rolling at 950° C. with a rolling reduction of 50%. Particles of 2 to 6 μm in size were observed in the cast alloys, and after hot rolling, the particle size was shown to decrease to less than 1 μm.

[0111] SEM-EDS analysis confirmed that all particles observed in the alloy after casting and hot rolling were δ-Ni2Si. These particles are believed to have formed during the cooling process of the specimen during casting or hot rolling. During the solidification process after casting, Ni2Si particles crystallized to form coarse inclusions several micrometers in size. Most of these inclusions dissolved in the Cu matrix during the 950°C heat treatment for hot rolling. As the specimen cooled, their solubility decreased, resulting in the precipitation of Ni2Si. It was analyzed that heterogeneous nucleation occurred in areas with high energy, such as the grain boundaries and shear bands, resulting in the formation of relatively large particles (0.8 μm or larger), while homogeneous nucleation occurred within the matrix, resulting in the formation of small particles (0.4 μm or smaller). After hot rolling, it was confirmed that although not all particles were uniformly dispersed, they formed without significant agglomeration.

[0112] 14 is an image showing the texture around particles after hot rolling at an 85% cross-sectional area reduction in the copper-nickel-silicon alloys produced by Comparative Example 2 and Example 2 of the present application. From (a) in FIG. 14, after cold rolling at an 85% reduction, particles with sizes of about 0.6 to 1 μm were observed dispersed at intervals of about 2 to 3 μm near the Cu-4.5Ni-1Si alloy grain system.

[0113] The grains of the specimen after cold rolling and the specimen after hot rolling were comparable in size. This means that the grains of the specimen remained intact even with a cold rolling reduction of 85%. As a result, it is expected that the strain energy generated by cold rolling is not used to distort or destroy the grains, but rather induces large strain in the surrounding matrix structure.

[0114] As shown in Figure 14(c), the KAM analysis results showed that particle-affected deformation zones (PADZs) formed around the particles after cold rolling. These had higher strain energy than the matrix, and strong strain was concentrated especially between the particles. In addition, sub-grains with different crystal orientations from the surrounding matrix were observed between specific particles.

[0115] Therefore, unlike the matrix, which is primarily subjected to planar deformation during rolling, the regions between grains undergo a high level of combined deformation, generated by planar and shear deformation, during cold rolling. This can lead to the formation of subgrains with different crystal orientations from the matrix between the grains. The grain-affected deformation zones (PADZs) around the grains, especially the regions between the grains, can accumulate very high strain energy after rolling, unlike the rest of the matrix. It is believed that these regions have a relatively higher driving force for recrystallization than other regions.

[0116] Figures 15(a)-(b) are images showing (111) pole figures analyzed by XRD after cold rolling the copper-nickel-silicon alloys produced by Comparative Example 2 and Example 2 of the present application at rolling reductions of 85% and 90%. An ideal (111) pole figure for a face-centered cubic (FCC) alloy is shown in Figure 15(c). After cold rolling at rolling reductions of 85% and 90%, the copper-nickel-silicon alloy exhibits a texture of brass, copper, and S, which is a typical β-fiber structure. It was confirmed that the intensity of the rolling texture increases as the rolling reduction increases from 85% to 90%.

[0117] In the process of Example 2, a relatively small rolled texture is generated by intermediate heat treatment after rolling at a reduction rate of 85%, whereas in the process of Comparative Example 2, a relatively large amount of rolled texture is generated by continuous cold rolling at a reduction rate of 90%. Such a difference in texture can have a significant effect on the recrystallized texture generated by the subsequent solution treatment.

[0118] After cold rolling at a reduction ratio of 85%, the texture of the copper-nickel-silicon alloy of Example 2 was analyzed using high-magnification EBSD. Figures 15(d) to 15(g) show the results of microstructure and texture analysis of the copper-nickel-silicon alloy cold-rolled at a reduction ratio of 85%. Figure 15(f) shows β-fiber grains elongated along the rolling direction, most of which were analyzed to contain sulfur and brass components. Additionally, numerous shear bands inclined at approximately 20° to 30° to the rolling direction were formed within the strained grains.

[0119] According to Figure 15(g), these shear bands were analyzed to have higher strain energy than other shear bands. These shear bands were shown to be aligned with the Goss orientation, as seen in Figure 15(e) and (f) A and B. In addition, specific grain systems with high strain energy were observed, which were determined to be due to particle-affected deformation zones (PADZs) induced by particles in the grain systems during cold rolling.

[0120] Figure 16 shows images showing the IQ, IPF, texture, and KAM results for the copper-nickel-silicon alloys produced by Comparative Example 2 and Example 2 of the present application after cold rolling and intermediate heat treatment. From (d) of Figure 16, it can be seen that recrystallization has occurred in some shear bands and grain systems after the intermediate heat treatment. From (g) of Figure 16, it can be seen that some shear bands and grain systems have relatively large strain energy compared to the matrix, which suggests that recrystallization will begin during the intermediate heat treatment.

[0121] The Goss texture is mainly found in shear bands, whereas the Cube orientation ({100} <001> For high-resolution EBSD analysis, the shear bands and recrystallized regions within the grain system are labeled A and B in Figure 16(b).

[0122] FIG. 17 shows images of the microstructure analysis results of the grain system and shear band region (regions marked A and B in FIG. 16) of the copper-nickel-silicon alloys produced by Comparative Example 2 and Example 2 of the present application after intermediate heat treatment at 700°C for 1 hour. According to (a) to (c) of FIG. 17, particles approximately 1 μm in size are dispersed along the grain system. In (c) of FIG. 17, the red arrow indicates a Cube-oriented grain. Recrystallized grains approximately 5 to 10 μm in size were observed around the grain. These recrystallized grains may be generated in the particle-affected deformation zone (PADZ) during the intermediate heat treatment. Approximately half of these grains have Cube orientation.

[0123] However, according to Fig. 17(d), the grain system without grains did not recrystallize after annealing. This result indicates that only the grain-affected deformation zone (PADZ) can recrystallize during the intermediate heat treatment, and most of these may form grains oriented in the Cube direction.

[0124] Numerous experimental and simulation-based studies have investigated the preference for the formation of cube texture during recrystallization after cold rolling in face-centered cubic (FCC) alloys. Most of the mechanisms explained in these studies rely on oriented growth theory, which states that within a population of randomly oriented nuclei, those that find the most favorable conditions for growth relative to the matrix texture that surrounds them tend to grow fastest. Such accelerated growth becomes the dominant factor in defining the recrystallization texture.

[0125] One of the representative models based on oriented growth theory is the strain-energy-release-maximization theory (SERM). The model proposed in Int. J. Mech. Sci. 42(8)(2000)1645-1678 assumes that recrystallization reduces the stored energy through the rolling process, facilitating the nucleation and growth process.

[0126] The release of strain rate energy is maximized when the absolute maximum stress direction (AMSD) in a high-energy matrix structure is aligned with the minimum Young's modulus direction (MYMD) of the stress-free crystal. The model can predict the preferred recrystallization direction in sinter-deformed copper alloys. The MYMD of a copper alloy can be calculated from the Young's modulus of a cubic crystal using the following equation: [Formula 1] 1 / E=S 11 +[S 44 -2(S 11 -S 12 )](a 11 2 a 12 2 +a 12 2 a 13 2 +a 13 2 a 11 2 )

[0127] In the above formula 1, E is Young's modulus, S ij is the compliance rate, a ij is an arbitrary tensile direction x i The axis of symmetry x j is the directional cosine related to the elastic constants (S 11 =0.0232, S 44 =0.0182, S 12 =-0.00101), calculation “S 44 -2(S 11 -S 12 ) actually calculates a negative value. This is because the orientation component is "a 11 =a 12 =a 13 This shows that the minimum Young's modulus is achieved when MYMD is 0. <100> This is along the normal direction of rolling (ND), the rolling direction (RD) of the material, and the transverse direction (TD). <100> This means that the oriented cube texture minimizes the Young's modulus of the copper alloy at the intermediate heat treatment temperature.

[0128] Therefore, compared with other orientations, the Cube texture is more likely to grow preferentially during intermediate heat treatment due to more efficient energy release. Also, according to the orientation growth theory, the 40° angle between the S texture and the Cube texture is <111> The orientation relationship indicates that cube-oriented grains have high grain mobility with S-oriented grains. They can grow faster by absorbing S-oriented grains during intermediate heat treatment. Therefore, PADZs with high strain energy, especially those with S-oriented grains, are easily recrystallized with cube texture.

[0129] Figures 17(d) to (f) present the EBSD analysis results for the recrystallized region within the shear band (area B in Figure 16). The recrystallized grains along the shear band were confirmed to have a Goss orientation that was aligned with the original shear band orientation before aging. This indicates that the original crystal orientation in the shear band before aging is maintained after recrystallization. The SERM model compares the AMSD of a specific orientation with the MYMD of a face-centered cubic (FCC) Cu alloy and can predict the probability of maintaining a specific texture during recrystallization.

[0130] The model assumes that when the AMSD of a particular grain is aligned with the MYMD of a Cu alloy, the original orientation is more likely to remain unchanged during recrystallization. This approach can explain the recrystallization of a Cu-Ni-Si alloy from shear bands to a Goss texture after intermediate heat treatment. The Taylor-Bishop-Hill model with global constraints was used to calculate the AMSD of a Goss-oriented (110)

[0001] crystal in a shear band. During planar deformation compression, the active slip systems are identified as (111) [0-11], (111) [-101], (-1-1)

[0011] , and (-1-1)

[0101] . These selected slip directions are associated with forming an acute angle with the maximum strain direction

[0001] . Adding up all these directions, the AMSD is [0-11] + [-101] +

[0011] +

[0101] =

[0004] /

[0001] .

[0131] Such AMSD is consistent with the MYMD of face-centered cubic (FCC) copper. Therefore, Goss-aligned shear bands in rolled Cu-Ni-Si alloys may not change orientation after recrystallization. This phenomenon has been reported for many face-centered cubic (FCC) metals. However, it is important to consider that the crystal orientation of the shear bands may not be exactly Goss oriented due to complex strain introduced during rolling. Therefore, not only Goss but potentially other orientations may also be Goss. However, the grains in the shear bands preferentially recrystallize into the Goss texture while maintaining their orientation rather than forming a Cube texture.

[0132] Figure 18 is an image showing the change in microstructure of copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2 of the present application. In Example 2, Ni2Si particles with sizes of 0.5 to 2.0 μm are generated and dispersed after hot rolling. A strong electric field is generated around the Ni2Si particles by cold rolling. After the intermediate heat treatment process, a cube texture is recrystallized around the Ni2Si particles.

[0133] 19 shows images of the recrystallized microstructures of the copper-nickel-silicon alloys produced in Comparative Example 2 and Example 2 of the present application after one minute of solution treatment. Previous microstructure analysis confirmed that intermediate heat treatment generates Cube-oriented grains in the particle-affected deformation zone (PADZ) and specific shear bands. To investigate the microstructural changes in the copper-nickel-silicon alloy of Example 2 without intermediate heat treatment, the recrystallized microstructures after solution treatment were analyzed.

[0134] In order to analyze the recrystallization behavior in the initial step of solution treatment in a copper-nickel-silicon alloy, the structure after solution treatment at 900°C for 1 minute during the process of Comparative Example 2 and Example 2 was examined.

[0135] Despite the short heat treatment times, both copper-nickel-silicon alloys were observed to have a largely recrystallized microstructure. In particular, the alloy prepared according to Example 2, which included an intermediate heat treatment, had larger grains than the alloy prepared according to Comparative Example 2 after 1 minute of solution treatment. This may be due to the recrystallized grains already formed during the intermediate heat treatment in the copper-nickel-silicon alloy prepared according to Example 2. Furthermore, in the copper-nickel-silicon alloy of Comparative Example 2, the Cube-oriented grains were smaller than the surrounding grains. In contrast, the Cube-oriented grains in the copper-nickel-silicon alloy of Example 2 were comparable in size to or larger than the other grains. In the copper-nickel-silicon alloy of Example 2, the Cube-oriented grains may grow by absorbing other grains during subsequent heat treatment. In contrast, in the copper-nickel-silicon alloy of Comparative Example 2, the expansion of neighboring grains during additional heat treatment may hinder the growth of the Cube-oriented grains.

[0136] 20 shows IPF and ODF images and a graph of texture area fraction obtained by analyzing the structure of fully recrystallized Cu-Ni-Si alloys after solution treatment of the copper-nickel-silicon alloys produced according to Comparative Example 2 and Example 2 of the present application. The copper-nickel-silicon alloy produced according to Comparative Example 2 was solution treated for 10 minutes, while the copper-nickel-silicon alloy produced according to Example 2 was solution treated for 5 minutes, yet both exhibited comparable grain sizes of approximately 20 μm.

[0137] However, there was a clear difference in the structure of the Cu-Ni-Si alloy. In the copper-nickel-silicon alloy produced according to Comparative Example 2, which did not undergo an intermediate heat treatment, 3% of Cube-oriented grains were observed after solution treatment. In contrast, the copper-nickel-silicon alloy produced according to Example 2 had very high rolling textures of S, Copper, and Brass orientations, at approximately 24%, 13%, and 10%, respectively. The copper-nickel-silicon alloy produced according to Example 2 showed a reduced proportion of these textures, with S, Copper, and Brass textures at approximately 15%, 6%, and 12%, respectively. This texture trend was consistent with that of the copper-nickel-silicon alloy that had undergone thermomechanical treatment.

[0138] The copper-nickel-silicon alloy produced in Example 2, which was cold-rolled at a reduction ratio of 30%, had an increased area fraction of the rolled texture and a slight decrease in the separation of the cube texture compared to the alloy after solution treatment, but the difference was very small.

[0139] As a result, including an intermediate heat treatment step before the solution treatment resulted in a higher proportion of cube-oriented grains after recrystallization due to the solution treatment. In particular, the particles of the Cu-Ni-Si alloy play a key role in the formation of cube-oriented grains during the intermediate heat treatment. Therefore, the cube texture can be formed during the intermediate heat treatment in the particle-affected deformation zone (PADZ) due to the high strain rate energy.

[0140] These Cube-oriented grains grow into coarse Cube texture during solution treatment, increasing the proportion of Cube texture in Cu-Ni-Si alloys. However, in grain-free regions, sufficient strain energy can be induced by cold rolling to form Cube-oriented grains. As a result, grains lacking the appropriate deformation rate can be recovered during solution treatment while maintaining their previous crystallographic orientation.

[0141] Unlike Comparative Example 2, an intermediate heat treatment step was added to the manufacturing process of the Cu-4.5Ni-Si alloy according to Example 2, which effectively induces the formation of a substantial amount of Cube-oriented grains, which results in improved bendability without reducing the strength of the alloy.

[0142] The manufacturing process of the copper-nickel-silicon alloy including the intermediate heat treatment can be smoothly applied to the current commercial manufacturing process, and the commercial usability of the copper-nickel-silicon alloy can be improved by improving the bending workability without reducing the hardness, tensile strength, ductility, and electrical conductivity.

[0143] Although certain parts of the present application have been described in detail above, it is obvious to those skilled in the art that these specific techniques are merely preferred embodiments and do not limit the scope of the present application. Therefore, the true scope of the present application is defined by the appended claims and their equivalents.< / uvw> < / uvw> < / def>

Claims

1. of the total weight of the copper-nickel-silicon alloy, 3 to 4.5 wt. % nickel (Ni); 0.7 to 1.0 wt. % silicon (Si); copper (Cu) and the balance being unavoidable impurities; A copper-nickel-silicon alloy with improved bending workability, in which the area fraction of {100}<001> (Cube orientation) is 3% or more after a solution treatment process.

2. 2. The copper-nickel-silicon alloy with improved bending workability according to claim 1, wherein the area fraction of {112}<111> (Copper orientation) is 11% or less after the solution treatment step.

3. 2. The copper-nickel-silicon alloy with improved bending workability according to claim 1, wherein after the intermediate heat treatment step, the area fraction of the recrystallized structure is 5% to 65%, of which the area fraction of {100}<001> (Cube orientation) is 15% or more.

4. Ni in the intermediate heat treatment process ２ 2. The copper-nickel-silicon alloy with improved bending workability according to claim 1, wherein a Cube texture is formed around the Si particles.

5. 0.5 μm to 2.0 μm Ni ２ 2. The copper-nickel-silicon alloy with improved bending workability according to claim 1, wherein Si particles are distributed.

6. The copper-nickel-silicon alloy with improved bending workability according to claim 1, wherein the copper-nickel-silicon alloy has a 90° bending test performance in which the ratio R / t of the bending radius R to the plate thickness t is 0.25 or more.

7. 2. The copper-nickel-silicon alloy according to claim 1, wherein a thin plate having a thickness of 10 μm to 500 μm has a ratio R / t of the bending radius R to the plate thickness t of 0.25 to 2.0, and the bending direction is 90° in the rolling vertical and horizontal directions, with no cracks occurring when the alloy is completely in contact with the rolling vertical and horizontal directions.

8. 2. The copper-nickel-silicon alloy according to claim 1, wherein the copper-nickel-silicon alloy has a tensile strength of 800 MPa or more and an electrical conductivity of 30% IACS or more.

9. 2. The copper-nickel-silicon alloy with improved bendability according to claim 1, wherein the copper-nickel-silicon alloy has an average Taylor factor of 3.2 or less.

10. 2. The copper-nickel-silicon alloy with improved bending workability according to claim 1, wherein the copper-nickel-silicon alloy with improved bending workability is in the form of a sheet or plate.

11. i) casting a copper-nickel-silicon alloy containing 3 to 4.5 wt. % nickel (Ni), 0.7 to 1.0 wt. % silicon (Si), and the balance copper (Cu) and unavoidable impurities, based on the total weight of the copper-nickel-silicon alloy; ii) rolling the cast copper-nickel-silicon alloy; iii) intermediate heat treatment of the rolled copper-nickel-silicon alloy at 600°C to 800°C for more than 0 minutes and up to 30 minutes; iv) rolling the intermediate heat treated copper-nickel-silicon alloy; and v) solution treating the rolled copper-nickel-silicon alloy.

12. vi) cold rolling the solution treated copper-nickel-silicon alloy; vii) subjecting the cold rolled copper-nickel-silicon alloy to a precipitation treatment.

13. 12. The method for producing a copper-nickel-silicon alloy with improved bendability according to claim 11, wherein the solution treatment in step v) is performed at a temperature of 850°C or higher but lower than 950°C for more than 0 minutes but not more than 30 minutes.

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