Oxygen-free copper alloy rod and preparation method thereof

Abstract

The invention discloses an oxygen-free copper alloy rod and a preparation method thereof, the alloy rod comprises an oxygen-free copper matrix, an element Cr, an element Zr and an element Ag, the content of the element Cu in the oxygen-free copper matrix is greater than or equal to 99.95 wt.%, the oxygen content is less than or equal to 5 ppm, the content of the element Cr is 0.1-0.3 wt.%, the content of the element Zr is 0.05-0.15 wt.%, and the content of the element Ag is 0.01-0.1 wt.%. The preparation process comprises the steps of vacuum melting, stirring, continuous casting and continuous rolling integrated machining and gradient aging treatment. According to the invention, the performance is synergistically improved through component optimization and process innovation, and the preparation process has uniqueness and unexpected technical effects, so that the defect that the strength and the conductivity cannot be balanced in the prior art is overcome. And the tensile strength is greater than or equal to 450Mpa while the electric conductivity is greater than or equal to 95% IACS.

Description

Technical Field

[0001] The present invention relates to the technical field of copper alloy processing, in particular to an oxygen-free copper alloy rod and a preparation method thereof. Background Art

[0002] Oxygen-free copper (OFC) is widely used in the electrical and electronic fields due to its excellent electrical conductivity (≥100% IACS), but its low strength (tensile strength approximately 200 MPa) makes it difficult to meet the demands of high-load scenarios. Traditional strengthening methods (such as adding elements like Cr and Zr) can improve strength but significantly reduce conductivity. For example, C19200 alloy, an iron-copper alloy, has a conductivity of only 80% IACS despite the addition of Cr and Zr, which improves strength. Achieving a balance between strength and conductivity in oxygen-free copper alloy rods is difficult.

[0003] With the current higher requirements for oxygen-free copper in the electronic and electrical fields and the demand for high-load scenarios, how to ensure conductivity ≥ 95% IACS while achieving tensile strength ≥ 450 MPa is a technical problem that needs to be focused on.

[0004] In view of this, this patent application is filed. Summary of the Invention

[0005] In order to solve the technical problem that the current oxygen-free copper alloy rod cannot achieve both strength and conductivity, especially the inability to achieve a tensile strength of ≥450 MPa while ensuring a conductivity of ≥95% IACS, the present invention provides an oxygen-free copper alloy rod and a preparation method thereof.

[0006] The first object of the present invention is to provide an oxygen-free copper alloy rod, comprising an oxygen-free copper matrix, elemental Cr, elemental Zr, and elemental Ag, wherein the oxygen-free copper matrix has an elemental Cu content ≥99.95wt.%, an oxygen content ≤5ppm, an elemental Cr content of 0.1-0.3wt.%, an elemental Zr content of 0.05-0.15wt.%, and an elemental Ag content of 0.01-0.1wt.%.

[0007] In the present invention, the oxygen content in the oxygen-free copper matrix is ​​designed to be ≤5ppm, which is 67% lower than the conventional non-vacuum melting oxygen content, which is beneficial to the improvement of strength. Elemental Cr can form 5-20nm Cr particles, which improves strength by pinning dislocations. The addition of elemental Zr can form a composite precipitate phase with Cr to obtain a nano-precipitate phase, which can inhibit the coarsening of Cr particles at high temperatures (experimental verification shows that the size of Cr particles only increases by 5% after aging at 150°C for 1000 hours, while the coarsening rate of conventional Cr alloys is >30%). At the same time, it is strengthened by solid solution (Cr, Zr, Ag and other alloy elements dissolve in the copper matrix during vacuum melting to form a solid solution) to improve high-temperature stability (experimental verification shows that the tensile strength retention rate is 95%). In the present invention, the Ag element plays an auxiliary strengthening role: Ag can increase the recrystallization temperature to ≥280°C (the crystallization temperature of conventional oxygen-free copper is 220°C), inhibit dynamic recovery during cold rolling, and keep the dislocation density at 10 12 / cm 2 Above (conventional process 10 11 / cm 2 ), improving strength and stability. The addition of silver also increases the recrystallization temperature, thereby improving the conductivity of the alloy rod. In this invention, a balance between strength and conductivity is achieved through optimization of the alloy composition.

[0008] In an optional embodiment, a rare earth element is further included, wherein the rare earth element is La and / or Ce, and the content of the rare earth element is 0.02-0.05 wt.%. Preferably, the rare earth element is La.

[0009] The addition of rare earth elements in this invention forms a rare earth-oxygen composite interface layer, refining grains to ≤5μm and achieving high-angle grain boundaries (≥15°). The proportion of high-angle grain boundaries increases from 30% to 75%. According to grain boundary scattering theory, for every 10% increase in high-angle grain boundary density, grain boundary resistance decreases by 8%, achieving a balance between grain refinement and conductivity preservation.

[0010] In an optional embodiment, the content of impurity elements is ≤0.001 wt.%, and the impurity elements include S and P.

[0011] A second object of the present invention is to provide a method for preparing any of the above oxygen-free copper alloy rods, comprising the following steps: S1: Vacuum-melt the electrolytic copper, then add various raw materials and perform deoxidation to obtain a metal melt; S2: Stirring continuous casting: the metal melt is cast to obtain an equiaxed fine-grained ingot, and stirring is applied synchronously during the casting process; S3: Warm rolling: preheat the billet to 400℃ and roll it, with the deformation of each pass ≤15%; S4: Cold rolling strengthening: cooling rollers, rolling at room temperature; S5: Online annealing: After the third pass of the cold rolling strengthening process, online annealing is performed, and then cold rolling strengthening is continued; S6: Gradient aging treatment.

[0012] The traditional process for preparing oxygen-free copper alloy rods is as follows: (1) smelting: non-vacuum smelting + multiple refining, (2) rolling: hot rolling + cold rolling + intermediate annealing (multiple times, such as 3 times). The final yield is about 85%.

[0013] In the present invention, vacuum melting integrated deoxidation is adopted, which is beneficial to reducing energy consumption; in the rolling process, continuous casting and rolling + online annealing are adopted to simplify the process flow, and the yield of finished products reaches 95%; synchronous stirring is adopted in the continuous casting process to obtain equiaxed fine-grained ingots, which is helpful for improving the tensile strength and conductivity of the product; online annealing is adopted to shorten the processing time and also improve the conductivity (modify lattice defects); the use of continuous casting and rolling + online annealing synergistically further improves the tensile strength and conductivity, ensuring that the conductivity is ≥95%IACS while achieving a tensile strength ≥450Mpa.

[0014] In an optional embodiment, in step S1, when the electrolytic copper is vacuum melted, the temperature is 1200°C and the vacuum is drawn to 2×10 -3 Pa.

[0015] In an optional embodiment, in step S1, during the deoxidation treatment, an inert gas is blown into the molten pool for 15 minutes; The stirring speed is 300 r / min, and the inert gas is argon; And / or, after the deoxidation treatment, a Ca-Si flux is added to remove scum to treat impurities; And / or, the Ca-Si flux is added at a molar ratio of Ca:Si=1:2, and the amount of the Ca-Si flux added is 0.2 wt.% of the mass of the metal melt.

[0016] In an optional embodiment, in step S2, during the stirring casting, a Φ20 mm crystallizer is used for casting, and electromagnetic stirring with a frequency of 30 Hz and a magnetic field strength of 0.2 T is simultaneously applied, and the casting speed is 1.2 m / min.

[0017] In the present invention, electromagnetic stirring is carried out synchronously during the casting process, which can inhibit the growth of columnar crystals and obtain equiaxed fine-grained ingots.

[0018] In an optional embodiment, in step S3, during the warm rolling, the slab is preheated to 400°C and rolled to Φ15mm, with a deformation of 43.75%; In step S4, during cold rolling strengthening, a mixed spray of liquid nitrogen and / or ethanol is used to cool the rollers, the roller surface temperature is -70°C to -50°C, and the rollers are rolled at room temperature until the diameter is 6 to 8 mm, the total deformation is 84% ​​to 91%, and the rolling speed is 15 m / s to 20 m / s; And / or, during the cold rolling strengthening, the number of passes is 2 to 5.

[0019] In the present invention, the use of electromagnetic stirring + high deformation (84% to 91%) rolling is beneficial to reducing electron scattering and improving conductivity.

[0020] In an optional embodiment, in step S5, during the online annealing process, the material is heated to 300°C at a rate of 150-200°C / min and water quenched, with a dwell time of ≤3s.

[0021] In an optional embodiment, in step S6, the gradient aging process is: The first stage: 250℃ for 1 hour; In the second stage, the temperature is lowered to 200℃ and kept for 2 hours, and then the furnace is cooled to below 50℃ and taken out of the furnace; And / or, when the oxygen-free copper alloy rod contains rare earth elements, a third stage is added to the gradient aging treatment: keeping the temperature at 150° C. for 4 hours.

[0022] The gradient aging treatment in the present invention makes the temperature control stage more precise and the cooling controllable. This method can refine the precipitated phase and perform rare earth strengthening, thereby increasing the strength of the product by 5%-10%. In terms of conductivity, it can reduce scattering and rare earth purification, thereby increasing the conductivity by 2%-5% IACS.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention achieves synergistic performance improvements through composition optimization and process innovation of oxygen-free copper alloy rods. This unique and unexpected manufacturing process overcomes the existing art's inability to balance strength and conductivity, achieving a tensile strength of 450 MPa while maintaining a conductivity of 95% IACS or higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings: Figure 1 This is a flow chart of the method for preparing an oxygen-free copper alloy rod of the present invention. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0026] The "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values ​​and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise indicated, the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0027] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0028] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0029] If not otherwise specified, all steps of this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include step (a) performed sequentially. and (b), and may also include steps (b) and (a) performed sequentially. For example, the method may further include step (c), means that step (c) can be added to the method in any order, for example, the method may include steps (a), (b) and (c), It may also include steps (a), (c) and (b), or it may include steps (c), (a) and (b), etc.

[0030] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0031] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0032] Example 1: Alloy formula: Cu: balance (purity ≥99.99%), oxygen content: 3ppm; Cr: 0.20wt.%, Zr: 0.10wt.%, Ag: 0.05wt.%.

[0033] Production process, such as Figure 1 As shown in: (1) Vacuum melting Equipment: ZG-0.05 vacuum induction melting furnace (limited vacuum ≤ 5×10 -4 Pa).

[0034] step: Place the electrolytic copper plate (Cu≥99.99%) into the graphite crucible and evacuate to 2×10 -3 Pa, heated to 1200℃ and melted.

[0035] Cr (pure metal block), Zr (Cu-Zr master alloy) and Ag (pure silver wire) are added in sequence through a vacuum feeding system.

[0036] Deoxidation treatment: Turn on the graphite rotor (speed 300 r / min) and blow high-purity argon gas (flow rate 8 L / min, purity 99.999%) into the molten pool for 15 minutes to obtain a metal melt.

[0037] Slag removal: Add Ca-Si flux (Ca:Si=1:2) accounting for 0.2wt.% of the mass of the metal melt (copper matrix + alloy elements), let it stand for 10 minutes and then skim off the slag.

[0038] (2) Continuous casting and rolling integrated processing equipment: Electromagnetic stirring continuous casting machine (equipped with a frequency-adjustable rotating magnetic field generator); Four-roller liquid nitrogen cooling rolling mill (roller diameter Φ300mm, surface laser texturing treatment Ra=2.0μm).

[0039] step: a. Stirring continuous casting: The melt is transferred into a holding furnace (argon protection) and cast through a Φ20mm crystallizer. Electromagnetic stirring with a frequency of 30 Hz and a magnetic field strength of 0.2 T is applied simultaneously, and the casting speed is 1.2 m / min.

[0040] b. Cold rolling strengthening: cooling rollers, rolling at room temperature: First pass: preheat the billet to 400°C and roll it to Φ15mm (deformation 43.75%); Second to fourth passes: liquid nitrogen cooling of the rolls (roller surface temperature -50°C), rolling to Φ8mm at room temperature (total deformation 84%), rolling speed 15m / s.

[0041] c. Online annealing: After the third pass, an induction annealing device (power 50kW) is inserted, instantaneously heated to 300°C and water quenched (residence time ≤ 3s).

[0042] (3) Gradient aging Equipment: Segmented controlled atmosphere aging furnace (N2 protection, oxygen content ≤10ppm).

[0043] step: The first stage: keep warm at 250℃ for 1 hour, and introduce N2-5% H2 mixed gas into the furnace (to prevent oxidation); The second stage: cool down to 200℃ and keep it for 2 hours, then cool down to below 50℃ and take it out of the furnace.

[0044] Performance testing: Mechanical properties: The tensile strength measured by a universal material testing machine (ASTM E8 standard) is 460 MPa and the elongation is 12%; Electrical conductivity: 96% IACS measured by eddy current conductivity meter (Sigmatest2.069).

[0045] Example 2: Alloy formula: Cu: balance, Cr: 0.25wt.%, Zr: 0.12wt.%, Ag: 0.08wt.%, La: 0.03wt.% (added in the form of Cu-La master alloy), oxygen content: 4ppm.

[0046] Production process: (1) Vacuum melting Equipment: ZG-0.05 vacuum induction melting furnace (limited vacuum ≤ 5×10 -4 Pa).

[0047] step: Place the electrolytic copper plate (Cu≥99.99%) into the graphite crucible and evacuate to 2×10 -3Pa, heated to 1200℃ and melted.

[0048] Cr (pure metal block), Zr (Cu-Zr master alloy), Ag (pure silver wire), and Cu-10% La master alloy (preheated to 200°C for degassing) are added in sequence through a vacuum feeding system. The La element in the Cu-10% La master alloy accounts for 10% of the alloy by weight.

[0049] Deoxidation treatment: Turn on the graphite rotor (speed 300 r / min) and blow high-purity argon gas (flow rate 8 L / min, purity 99.999%) into the molten pool for 15 minutes to obtain a metal melt.

[0050] Slag removal: Add 0.2wt.% of Ca-Si flux (Ca:Si=1:2) to the molten metal, let it stand for 10 minutes and then skim off the slag.

[0051] (2) Continuous casting and rolling integrated processing equipment: Electromagnetic stirring continuous casting machine (equipped with a frequency-adjustable rotating magnetic field generator); Four-roller liquid nitrogen cooling rolling mill (roller diameter Φ300mm, surface laser texturing treatment Ra=2.0μm).

[0052] step: a. Stirring continuous casting: The melt is transferred into a holding furnace (argon protection) and cast through a Φ20mm crystallizer. Electromagnetic stirring with a frequency of 30 Hz and a magnetic field strength of 0.2 T is applied simultaneously, and the casting speed is 1.2 m / min.

[0053] b. Cold rolling strengthening: cooling rollers, rolling at room temperature: First pass: preheat the billet to 400°C and roll it to Φ15mm (deformation 43.75%); Second to fifth passes: Use liquid nitrogen + ethanol mixed spray (volume ratio 1:1) to cool the roll (roll surface temperature drops to -70°C), and increase the cooling rate to 80°C / s; roll to Φ6mm at room temperature (total deformation 91%), the second to fourth passes rolling speed is 15m / s, and the fifth pass rolling speed is increased to 20m / s.

[0054] c. Online annealing: After the third pass, an induction annealing device (power 50kW) is inserted, instantaneously heated to 300°C and water quenched (residence time ≤ 3s).

[0055] (3) Gradient aging Equipment: Segmented controlled atmosphere aging furnace (N2 protection, oxygen content ≤10ppm).

[0056] step: The first stage: keep warm at 250℃ for 1 hour, and introduce N2-5% H2 mixed gas into the furnace (to prevent oxidation); The second stage: cool down to 200℃ and keep warm for 2 hours; The third stage: cooling to 150 ° C and keeping it for 4 hours to further stabilize the distribution of the precipitated phase.

[0057] Performance testing: Tensile strength 470MPa, conductivity 95.5%IACS, elongation 10%.

[0058] Comparing Example 2 with Example 1, when rare earth elements are added, the tensile strength of the obtained product is improved, and the electrical conductivity does not change much, still being above 95% IACS.

[0059] Example 3: The difference between this embodiment and embodiment 2 is that the content of element La in the formula is 0.02%, and the rest is the same as embodiment 2.

[0060] Example 4: In this embodiment, the content of element La in the formula is 0.05%, and the rest is the same as in Example 2.

[0061] The products obtained in Example 3 and Example 4 were tested, and the results are shown in Table 1 below.

[0062] Table 1

[0063] As can be seen from Table 1, the tensile strength of the products of Example 3 and Example 4 is good, and the conductivity is also above 95.0%, which is of great help in improving the strength of the products.

[0064] The product obtained by the present invention also has good high temperature stability, specifically: Example Test: The sample obtained in Example 1 was aged at 150°C for 1000 hours. The tensile strength and electrical conductivity were tested. The results were: Tensile strength retention rate: 95% (C19200 alloy only 85%); Conductivity fluctuation: ±0.5%IACS (C19200 fluctuation ±2%).

[0065] Mechanism analysis: The addition of Ag in the embodiment increases the recrystallization temperature (the recrystallization temperature in Example 1 is 280°C vs. the recrystallization temperature of C19200 is 220°C), which inhibits grain coarsening at high temperatures and improves the conductivity of the alloy rod.

[0066] Comparative Example 1: In this comparative example, the alloy formula lacks Zr and contains only Cr (0.20 wt.%). The specific formula is: Cu: balance (purity ≥ 99.99%), oxygen content: 3 ppm; Cr: 0.20 wt.%, Ag: 0.05 wt.%. The specific preparation process is the same as that of Example 1.

[0067] The product obtained in Comparative Example 1 was compared with the product of Example 1, and the results are shown in Table 2.

[0068] Table 2

[0069] As shown in Table 2, Comparative Example 1 and Example 1 use exactly the same process parameters (vacuum melting, electromagnetic stirring continuous casting, cold rolling + online annealing, gradient aging). The only variable is whether Zr is added. The strength drops to 420 MPa and the conductivity drops to 95% IACS, which shows the irreplaceable nature of Zr.

[0070] Furthermore, the inventors compared the properties of ordinary oxygen-free copper, C19200 alloy and Example 1. The results are shown in Table 3.

[0071] Table 3

[0072] Among them, the composition of ordinary oxygen-free copper is Cu content ≥ 99.95wt.%, does not contain alloy elements, and contains a small amount of impurities.

[0073] As can be seen from Table 3, the product of Example 1 has the following advantages: Strength improvement: 119% higher than ordinary oxygen-free copper and 31% higher than C19200 alloy; In terms of conductivity retention: despite the significant increase in strength, the conductivity still reaches 96% of pure copper (C19200 is only 80%).

[0074] This is mainly due to the following reasons: Theoretical basis: Nano-precipitate strengthening in Example 1: The Cr-Zr precipitate (15 nm) pins dislocations and improves strength. At the same time, because the size of the Cr-Zr precipitate is much smaller than the electron mean free path (~40 nm), it has little effect on conductivity.

[0075] Therefore, the present invention presents a synergistic optimization effect of the strength and electrical conductivity of the alloy, ensuring that the electrical conductivity is ≥95% IACS while achieving a tensile strength of ≥450 MPa.

[0076] Comparative Example 2: The difference from Example 1 is that electromagnetic stirring was not performed during the continuous casting and rolling. The results are shown in Table 4.

[0077] Table 4

[0078] It can be seen from this that electromagnetic stirring during continuous casting and rolling can improve the tensile strength and conductivity of the alloy rod obtained, while removing the stirring will have an adverse effect on the tensile strength and conductivity of the product.

[0079] Comparative Example 3: In this comparative example, continuous casting and rolling + intermediate annealing process is adopted, and the specific process is as follows: Alloy formula: same as Example 1.

[0080] Preparation process adjustment: The difference from the online annealing in Example 1 is that an intermediate offline annealing is performed in this comparative example, and the specific adjustment is as follows: During the cold rolling strengthening process in step (2), an offline intermediate annealing (temperature 300°C, holding for 30 minutes, air cooling) was performed after the second pass, and then rolling was continued to the target size. The remaining process was the same as in Example 1. The results are shown in Table 5.

[0081] Table 5

[0082] As can be seen from Table 5, when continuous casting and rolling with intermediate annealing are used, the tensile strength and electrical conductivity of the obtained product are not as good as those of the online annealing process after the third pass.

[0083] Comparative Example 6: In this comparative example, hot rolling + cold rolling + online annealing is adopted, and the specific process is as follows: Alloy formula: same as Example 1.

[0084] Preparation process adjustment: Different from the continuous casting and rolling in Example 1, this comparative example adopts the process of hot rolling + cold rolling, and the specific adjustment is as follows: Step a: Conventional hot rolling: The melt is cast into a Φ50 mm ingot, which is air-cooled and then heated to 800°C and hot-rolled to Φ20 mm.

[0085] Step b: Cold rolling strengthening: First pass: preheat the billet to 400°C and roll it to Φ15mm (deformation 43.75%); Second to fourth passes: liquid nitrogen cooling of the rolls (roller surface temperature -50°C), rolling to Φ8mm at room temperature (total deformation 84%), rolling speed 15m / s.

[0086] c. Online annealing: After the third pass, an induction annealing device (power 50kW) is inserted, instantaneously heated to 300°C and water quenched (residence time ≤ 3s).

[0087] The rest of the process is the same as in Example 1. The results are shown in Table 6.

[0088] Table 6 Performance test

[0089] Table 6 shows that the hot rolling + cold rolling + online annealing process results in reduced tensile strength and electrical conductivity. The present invention's continuous casting and rolling + online annealing process yields alloy rods with improved performance. Comparative Examples 5 and 6 demonstrate the necessity of the present invention's continuous casting and rolling + online annealing process for synergistically improving tensile strength and electrical conductivity.

[0090] Comparative Example 7: In this comparative example, the total deformation of cold rolling was changed, specifically: Alloy formula: same as Example 1.

[0091] Preparation process adjustment: Step b: Cold rolling strengthening: Cool the rollers and roll at room temperature: First pass: preheat the billet to 400°C and roll it to Φ15mm (deformation 43.75%); Second to fourth passes: Liquid nitrogen cooling of the rolls (roller surface temperature -50°C), rolling to Φ10mm at room temperature (total deformation 60%), pass deformation ≤15%, rolling speed 15m / s.

[0092] The test results of the obtained products are shown in Table 7.

[0093] Table 7: Performance test:

[0094] Table 7 shows that, compared with Example 1, decreasing the room-temperature rolling deformation decreases the conductivity of the resulting product. Therefore, the combination of electromagnetic stirring and high-deformation rolling (84%-91%) in the present invention is beneficial for reducing electron scattering and improving conductivity. Furthermore, decreasing the room-temperature rolling deformation also affects tensile strength.

[0095] Furthermore, the inventors compared the advantages of the process flow of the present invention with the existing process flow, as shown in Table 8.

[0096] Table 8

[0097] The material utilization rate of the present invention is also improved: Scrap recovery: Continuous casting and rolling integration reduces cutting head and tail losses (loss rate 2% in Example 1 vs. 8% in traditional process).

[0098] Impurity control: Vacuum melting + Ca-Si flux reduces waste slag by 50% (impurity adsorption efficiency increases to 90%).

[0099] In summary, the present invention achieves synergistic performance improvements through component optimization and process innovation, and provides a unique and unexpected technical effect in the preparation process, overcoming the performance deficiency of the existing technology that cannot balance strength and conductivity. It achieves a tensile strength of ≥450 MPa while ensuring a conductivity of ≥95% IACS.

[0100] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An oxygen-free copper alloy rod, characterized in that: The invention comprises an oxygen-free copper matrix, element Cr, element Zr and element Ag, wherein the oxygen-free copper matrix contains Cu element ≥99.95wt.%, oxygen content ≤5ppm, Cr element content 0.1-0.3wt.%, Zr element content 0.05-0.15wt.%, and Ag element content 0.01-0.1wt.%.

2. The oxygen-free copper alloy rod according to claim 1, characterized in that: It also includes rare earth elements, which are La and / or Ce, and the content of the rare earth elements is 0.02-0.05wt.%.

3. The oxygen-free copper alloy rod according to claim 1, characterized in that: The content of impurity elements is ≤0.001wt.%, and the impurity elements include S and P.

4. The method for preparing an oxygen-free copper alloy rod according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: Vacuum-melting the electrolytic copper, then adding various raw materials and performing deoxidation treatment to obtain a metal melt; S2: stirring continuous casting: the metal melt is cast to obtain an equiaxed fine-grained ingot, and stirring is applied synchronously during the casting process; S3: Warm rolling: preheat the billet to 400℃ and roll it, with the deformation of each pass ≤15%; S4: Cold rolling strengthening: cooling rollers, rolling at room temperature; S5: Online annealing: After the third pass of the cold rolling strengthening process, online annealing is performed, and then cold rolling strengthening is continued; S6: Gradient aging treatment.

5. The method for preparing an oxygen-free copper alloy rod according to claim 4, characterized in that: In step S1, when the electrolytic copper is vacuum melted, the temperature is 1200°C and the vacuum is drawn to 2×10 -3 Pa.

6. The method for preparing an oxygen-free copper alloy rod according to claim 4, characterized in that: In step S1, during the deoxidation treatment, an inert gas is blown into the molten pool for 15 minutes to perform the deoxidation treatment; The stirring speed is 300 r / min, and the inert gas is argon; And / or, after the deoxidation treatment, a Ca-Si flux is added to remove scum to treat impurities; And / or, the Ca-Si flux is added at a molar ratio of Ca:Si=1:2, and the amount of the Ca-Si flux added is 0.2 wt.% of the mass of the metal melt.

7. The method for preparing an oxygen-free copper alloy rod according to claim 4, characterized in that: In step S2 , during the stirring casting, a Φ20 mm crystallizer is used for casting, and electromagnetic stirring with a frequency of 30 Hz and a magnetic field strength of 0.2 T is applied simultaneously, and the casting speed is 1.2 m / min.

8. The method for preparing an oxygen-free copper alloy rod according to claim 4, characterized in that: In step S3, during the warm rolling process, the slab is preheated to 400°C and rolled to Φ15mm with a deformation of 43.75%; In step S4, during cold rolling strengthening, a mixed spray of liquid nitrogen and / or ethanol is used to cool the rollers, the roller surface temperature is -70°C to -50°C, and the rollers are rolled at room temperature until the diameter is 6 to 8 mm, the total deformation is 84% ​​to 91%, and the rolling speed is 15 m / s to 20 m / s; And / or, during the cold rolling strengthening, the number of passes is 2 to 5.

9. The method for preparing an oxygen-free copper alloy rod according to claim 8, characterized in that: In step S5, during the online annealing process, the steel is heated to 300°C at a rate of 150-200°C / min and water quenched, with a dwell time of ≤3s.

10. The method for preparing an oxygen-free copper alloy rod according to claim 4, characterized in that: In step S6, the gradient aging process is as follows: The first stage: 250℃ for 1 hour; In the second stage, the temperature is lowered to 200℃ and kept for 2 hours, and then the furnace is cooled to below 50℃ and taken out of the furnace; And / or, when the oxygen-free copper alloy rod contains rare earth elements, a third stage is added to the gradient aging treatment: keeping the temperature at 150° C. for 4 hours.

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