A copper alloy, a method for preparing the same, and an application thereof

Abstract

The application discloses a copper alloy and a preparation method and application thereof, and the copper alloy comprises the following components in mass percentage: Cu: 59.0-61.5 wt%, Te: 0.005-0.015 wt%, P: 0.01-0.02 wt%, As: 0.005-0.01 wt%, Si: <0.001 wt%, Al: <0.001 wt%, Sn: <0.001 wt%, Mg: <0.001 wt%, Fe: <0.005 wt%, Pb: <0.005 wt%, and Zn: the balance; and the proportion of beta phase in the copper alloy is less than 10%. The copper alloy is prepared by adopting hot rolling and online beta / alpha phase conversion heat treatment, the proportion of beta phase in the alloy is significantly reduced, the prepared copper alloy has excellent anti-zinc-removing performance, good processing plasticity and bending property, copper powder is not removed at a high speed of 800-1200 m / min, and the copper alloy has good electroplating performance, and has a wide application prospect in LED lamp lead support.

Description

Technical Field

[0001] This invention relates to the field of copper alloys, and more specifically to a copper alloy, its preparation method, and its application. Background Technology

[0002] The copper strip used in LED lamp lead brackets is mainly used as the base for the surface plating of LED lamp brackets and is an important component of LED lamps. Currently, the LED brass strip in the domestic market is C2680 (national standard H65). With the intensification of market competition, LED bracket manufacturers have proposed to reduce the copper content and use H60 as a substitute in order to reduce raw material procurement costs and improve market competitiveness.

[0003] H60 brass has a Zn content of over 38%, which is about 4% higher than that of C2680. When the Zn content of brass exceeds 38%, the alloy structure is α+β dual-phase brass. This structure contains a β solid solution based on the electron-electrolyte CuZn. The β solid solution is prone to dezincification at high temperatures and has poor corrosion resistance. During heat treatment and pickling, dezincification easily occurs, resulting in pitted defects on the copper strip surface. In later production, this leads to white spots on the stamped surface of the copper strip during electroplating, failing to meet customer requirements for the LED light bracket surface. Furthermore, the β phase of brass has a body-centered cubic lattice and poor plasticity at room temperature. During high-speed stamping, microcracks easily form in the β phase, causing copper powder to fall off. This fallen copper powder on the mold surface and in the gaps exacerbates mold wear and can even cause mold cracking during stamping, thus affecting the mold's service life.

[0004] Patent document CN107138551A discloses a method for preparing brass strip for LED lamp lead brackets, including: melting and casting C2680 alloy to produce ingots, hot rolling after heating to above the recrystallization temperature, removing the surface oxide layer, cold rolling, annealing, cold rolling, annealing, cold rolling, annealing, rolling the finished strip, cleaning, and tension straightening. This method uses appropriate heat treatment processes and annealing protective atmospheres, combined with roll grinding processes, to solve the problem of zinc deoxidation on the strip surface and reduce the surface roughness value of the strip.

[0005] Patent document CN113005326B discloses a copper alloy strip with the following mass percentage composition: Fe: 7-11 wt%, P: 0.006-0.012 wt%, Sn: 0.5-1.5 wt%, Ni: 4-6 wt%, with the balance being copper and unavoidable impurities. This invention, by controlling the addition content of elements such as Fe, Sn, Ni, and P, allows the Fe-rich phase to exist in the form of a framework within the copper matrix, thereby improving the strip's strength and bending performance. Simultaneously, it purifies the matrix and improves conductivity, enabling it to meet the performance requirements of LED lamp holders.

[0006] Although existing technologies have researched copper alloys for LED lamp brackets, current studies mostly use copper alloys with low zinc content, rather than H60 with higher zinc content. Therefore, it is of great significance to find a processing technology for H60 copper alloys that can improve the zinc dezincification pits on the surface and reduce the β phase ratio, producing high-zinc brass alloys that can withstand high-speed stamping without losing copper powder, while also exhibiting good electroplating performance, thus meeting the requirements for high-zinc brass alloys used in LED lamp lead brackets. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention provides a copper alloy with excellent anti-zincification properties, good processing plasticity and bending properties, and good electroplating performance, which can meet the requirements of modern high-speed precision stamping and effectively avoid the phenomenon of copper powder falling off after stamping.

[0008] A copper alloy comprising the following components by mass percentage: Cu: 59.0-61.5 wt%, Te: 0.005-0.015 wt%, P: 0.01-0.02 wt%, As: 0.005-0.01 wt%, Si < 0.001 wt%, Al < 0.001 wt%, Sn < 0.001 wt%, Mg < 0.001 wt%, Fe < 0.005 wt%, Pb < 0.005 wt%, and Zn as the balance; wherein the proportion of the β phase in the copper alloy is less than 10%.

[0009] This invention controls the Cu content to 59.0–61.5 wt% and optimizes the control of impurity elements Si, Al, Sn, Mg, Fe, and Pb to reduce the α phase region, thereby reducing the content of impurity elements with a large "Zn equivalent coefficient". This causes the α / (α+β) phase boundary to shift towards the Zn side, increasing the α phase region and reducing the β phase.

[0010] Preferably, the copper alloy contains 0.005-0.015 wt% Te, 0.01-0.02 wt% P, and 0.005-0.01 wt% As. Adding Te, P, and As to brass effectively reduces the potential difference between grains in the microstructure, thereby effectively reducing the rate of electrochemical corrosion. Dezincification corrosion can be mitigated or suppressed. The degree of dezincification during high-temperature heat treatment and pickling is reduced, meaning the formation of dezincification pits on the copper strip surface can be controlled. Surface electroplating performance is improved, meeting the customer's requirements for copper strip stamping surface electroplating in later production processes.

[0011] The proportion of the β phase in the copper alloy is controlled below 10%. The β phase has a body-centered cubic lattice, poor plasticity at room temperature, and a higher zinc content than the α phase, making it more prone to dezincification corrosion at high temperatures. During cold working of α+β dual-phase brass, the β phase is hard and brittle, easily leading to microcracks. When the β phase proportion in the dual-phase brass reaches 10% or more, the β phase tends to coalesce into spherical chains or plates, and with cold working, the cracks expand, resulting in powder shedding or processing cracking. Controlling the β phase proportion below 10% effectively controls copper powder shedding and cracking during cold working, while also reducing high-temperature dezincification corrosion of the alloy.

[0012] Preferably, the average grain size of the copper alloy is controlled between 4 and 8 μm. Currently, mainstream industry processes produce alloys of the same specifications with an average grain size between 15 and 25 μm, which is far higher than the average grain size of the copper alloy of this invention.

[0013] Preferably, the copper alloy has a hardness of 140-160 HV, a tensile strength of 470-530 MPa, an elongation of >25%, a roughness Ra <0.12 μm, and does not crack when bent at 180° R / T = 0.5 in the Goodway direction and at 180° R / T = 1 in the Badway direction.

[0014] This invention also discloses a method for preparing the copper alloy, which can produce H60 copper alloy products with excellent mechanical properties, a β phase ratio of less than 10%, and an average grain size of 4-8 μm, thus meeting the technical requirements of LED lamp lead frame products.

[0015] A method for preparing a copper alloy includes the following steps: batching and smelting → semi-continuous casting → hot rolling + online β / α phase transformation heat treatment → rough rolling → first micro-oxidation atmosphere step heat treatment → cleaning, grinding and polishing → intermediate rolling → second micro-oxidation atmosphere step heat treatment → cleaning, grinding and polishing → finished product rolling → cleaning, grinding and polishing.

[0016] In the hot rolling + online β / α phase transformation heat treatment process, the initial rolling temperature is controlled between 620-650℃, the final rolling temperature is controlled between 450-480℃, and after hot rolling, the hot-rolled strip is coiled online within 10 minutes and placed in a heat treatment furnace at a temperature of 450-460℃ for 3-4 hours. Within 5 minutes of exiting the furnace, the entire coil is hoisted into a water tank for water cooling to room temperature.

[0017] After hot rolling and online β / α phase transformation heat treatment, the β phase ratio of this alloy is controlled to be less than 10%. According to the copper-zinc binary equilibrium phase diagram, the solubility of zinc in copper can reach a maximum of 38.3% at 454℃ in α+β dual-phase brass. That is, the β phase ratio in α+β dual-phase brass is the smallest under equilibrium conditions at 454℃. Therefore, during the heat treatment at 450-460℃ for 3-4 hours, the β phase in α+β dual-phase brass is transformed and precipitated into the α phase. Within 5 minutes of exiting the furnace, the entire roll is suspended into a water tank for water cooling to room temperature. Through this rapid water cooling method, the α phase transformed and precipitated by this heat treatment process is retained, thereby ensuring that the β phase ratio of the alloy is controlled to be less than 10%, improving the processing plasticity and bending properties of the material, and solving the problem of copper powder falling off during high-speed stamping of H60.

[0018] Preferably, the roughing rate is ≥90%. The hot-rolled structure of the strip is completely broken down through roughing cold working, providing a prerequisite for the subsequent first micro-oxidation atmosphere step heat treatment to refine the grains.

[0019] Preferably, the process of the first and second micro-oxidation atmosphere stepped heat treatments is as follows: in a micro-oxidation atmosphere, the alloy copper strip is first heated to 300-320℃ at a heating rate of 75-85℃ / h and held at the first step for 2-3 hours, and then heated to 360-390℃ at a heating rate of 55-65℃ / h and held at the second step for 4-6 hours. The micro-oxidation atmosphere is a mixture of oxygen and nitrogen, and the oxygen content in the mixture is 3-5%.

[0020] When this alloy is heat-treated in a slightly oxidizing atmosphere, Cu2O and ZnO form on the surface of the copper strip, creating a protective oxide film that prevents zinc dezincification at high temperatures, effectively avoiding the formation of dezincification pits on the surface during heat treatment. Through stepped heat treatment, the first step, heating to 300-320℃ and holding for 2-3 hours, effectively releases the plastic distortion energy of the alloy microstructure during cold working, reducing the distortion energy within the second-step alloy microstructure and thus effectively preventing grain growth. The second step, holding at 360-390℃ for 4-6 hours, further softens the material, improving its processing plasticity. Controlling the heating rate within this range effectively improves the uniformity of the alloy's properties. After the first and second stepped heat treatments in a slightly oxidizing atmosphere, the average grain size of the finished product can be effectively controlled within 4-8 μm. Furthermore, refining the grain size can increase the surface area of ​​the grains, which can increase the conversion and precipitation of the β phase to the α phase during heat treatment, further reducing the proportion of the β phase. At the same time, it can also effectively reduce the diameter of the β phase, thereby improving the bending performance of the alloy and reducing the amount of copper powder lost during stamping.

[0021] Preferably, the intermediate rolling processing rate is ≥75%. The hot-rolled structure of the strip is completely broken down by intermediate rolling cold working, which provides the prerequisite for grain refinement in the subsequent second micro-oxidation atmosphere step heat treatment.

[0022] Preferably, the finished product rolling rate is controlled between 14% and 18%. The final product performance is controlled through work hardening. To ensure that the finished product meets the requirements of a hardness of 140-160 HV, a tensile strength of 470-530 MPa, and an elongation >25%, a finished product rolling rate of 14% to 18% is appropriate. When the finished product rolling rate is too low, the hardness and strength are insufficient; when the finished product rolling rate is too high, the strength exceeds the requirements, while the elongation is too low.

[0023] Preferably, the cleaning, grinding, and polishing process is as follows: degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, the second pair is 3000 mesh, the brush radius is 400-500 mm, the pressure is 30-50%, and the rotation speed is 1000-1500 r / min. Using relatively hard grinding brushes is intended to remove the 4-8 μm oxide layer from the surface, preventing pitting caused by zinc removal from affecting the electroplating properties of the material.

[0024] This invention also provides the application of the aforementioned copper alloy in LED lamp lead frame brackets. The copper alloy of this invention possesses excellent anti-zincification properties, good processing plasticity and bending properties, and good electroplating performance, making it a promising candidate for use in LED lamp lead frame brackets.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) Based on national standards, this invention optimizes the composition ratio of H60 copper alloy by adding trace amounts of Te, P, and As alloying elements to reduce the potential difference of the alloy's metallographic structure, thereby reducing the electrochemical corrosion rate of the alloy and inhibiting the dezincification phenomenon, thus avoiding the formation of dezincification pits on the alloy strip surface during heat treatment and pickling. At the same time, the rolling elements Si, Al, Sn, Mg, Fe, and Pb are optimized and controlled to reduce the interference of impurity elements, reduce the "Zn equivalent coefficient", and cause the α / (α+β) phase boundary to shift towards the Zn side, increasing the α phase region and reducing the β phase ratio.

[0027] (2) This invention controls the hot rolling temperature and the final rolling temperature by hot rolling and online β / α phase transformation heat treatment, and uses online heat treatment after hot rolling of the strip to perform β / α phase transformation heat treatment, so as to convert the β phase in α+β dual-phase brass into α phase, thereby reducing the proportion of β phase in the alloy, improving the processing plasticity and bending properties of the material, and solving the problem of copper powder falling off during high-speed stamping of H60.

[0028] (3) The heat treatment of this invention adopts a micro-oxidation atmosphere step heat treatment. The heat treatment atmosphere is a mixture of 3-5% oxygen and the balance nitrogen. During heat treatment, an oxide protective film is formed on the alloy surface, which prevents zinc dezincification of the copper strip at high temperature. This effectively avoids the formation of zinc dezincification pits on the surface of the alloy during heat treatment and improves the electroplating performance of the alloy. At the same time, the step heat treatment reduces the distortion energy inside the alloy structure in the first stage, thereby effectively preventing abnormal grain growth. With the large processing rate of rough rolling and intermediate rolling, plus this step heat treatment, the average grain size of the alloy can be effectively controlled within 4-8 μm. In addition, the refinement of grain size can increase the surface area of ​​the grains, which can increase the conversion and precipitation of β phase to α phase during heat treatment, further reducing the β proportion. At the same time, it can also effectively reduce the diameter of β phase, thereby improving the bending performance of the alloy and reducing the amount of copper powder lost during stamping.

[0029] (4) The grinding brush used in the grinding process of this invention is made of non-woven fabric + silicon carbide, with a mesh size of 2000-3000 mesh, a grinding brush radius of 300-500 mm, a pressure of 30-50%, and a rotation speed of 1000-1500 r / min. The purpose of using a relatively hard grinding brush is to remove the 4-8 μm oxide and dezincification layer on the surface, and to avoid the pits on the surface caused by dezincification affecting the electroplating properties of the material.

[0030] (5) The copper alloy strip prepared by this invention has a thickness of 0.1-0.25 mm, a hardness of 140-160 HV, a tensile strength of 470-530 MPa, an elongation of >25%, a roughness Ra <0.12 μm, an average grain size of 4-8 μm, a β phase ratio of <10%, and does not crack when bent at 180° R / T = 0.5 in the Goodway direction and at 180° R / T = 1 in the Badway direction. The copper alloy strip of this invention does not lose copper powder when stamped at high speeds of 800-1200 m / min, and has good electroplating performance, meeting the performance requirements of high-zinc brass strips for LED lamp lead brackets. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of this invention, but not all embodiments.

[0032] The chemical composition of the copper alloy strip in the embodiments of the present invention is shown in Table 1.

[0033] Table 1 Chemical composition (wt%) of copper alloy strip

[0034]

[0035] The preparation process of the copper alloy strip in this embodiment of the invention is as follows: batching and smelting → semi-continuous casting → hot rolling + online β / α phase transformation heat treatment → milling → rough rolling → edge trimming → first micro-oxidation atmosphere stepped heat treatment → cleaning, grinding and polishing → intermediate rolling → second micro-oxidation atmosphere stepped heat treatment → cleaning, grinding and polishing → finished product rolling → cleaning → tension bending and straightening. The specific steps are as follows:

[0036] S1, Ingredient Batching and Melting

[0037] Electrolytic copper is added to a smelting furnace and heated to a temperature of 1100-1120℃. Copper-tellurium master alloy, copper-phosphorus master alloy, and copper-arsenic master alloy are added according to the composition ratio. After all the master alloys have melted, the temperature is held for 20 minutes, then lowered to 1080-1100℃, and casting begins.

[0038] S2, Semi-continuous casting

[0039] Open the stopper rod and pour molten copper into the crystallizer. Then turn on the cooling water. When the molten copper level in the crystallizer reaches about two-thirds full, start the traction machine and begin casting at 20-30 mm / min. Turn on the vibration at a frequency of 60-80 times / min and an amplitude of 3-6 mm. Graphite powder is sprayed throughout the casting process. When the ingot reaches 0.5-1.0 meters, a steady-speed casting stage is reached, with the casting speed controlled at 130-150 mm / min and the primary cooling water flow rate controlled at 50-60 mm / min. 3 The water flow rate is controlled at 0.4-0.6 MPa, the cooling water temperature at 25-35℃, and the outlet water temperature at 40-50℃. The ingot casting dimensions are 200*620mm*8000mm.

[0040] S3, Hot rolling + Online β / α phase transformation heat treatment

[0041] The ingot heating temperature is 640–680℃, the holding time is 2–3 hours, the hot rolling start temperature is 620–650℃, the hot rolling rate is above 90%, and the hot rolling finish temperature is ensured to be 450–480℃, hot-rolled to a thickness of 14–16 mm, and the width after hot rolling extension is 650±5 mm. Within 10 minutes, the hot-rolled strip is coiled online and placed in the heat treatment furnace at the coiling point of the hot rolling process. The heat treatment furnace temperature is adjusted to 450–460℃ and held for 3–4 hours. Then, within 5 minutes of exiting the furnace, the entire coil is suspended into a water tank for water cooling to room temperature. After hot rolling and online β / α phase transformation heat treatment, the β phase ratio of the alloy microstructure is controlled to be below 10%.

[0042] S4, Milling Surface

[0043] The single-sided milling depth is 0.5 to 1.0 mm.

[0044] S5, rough rolling

[0045] The roughing rate is controlled at over 90%.

[0046] S6, trimming

[0047] The single-sided shearing is 7-10mm, and the bandwidth after shearing is 630±0.5mm.

[0048] S7, First step heat treatment in a slightly oxidizing atmosphere

[0049] The micro-oxidation atmosphere step heat treatment uses a mixed gas of 3-5% oxygen and the balance nitrogen. The heat treatment process is as follows: first, the alloy copper strip is heated to 300-320℃ at a heating rate of 75-85℃ / h and held at this first temperature for 2-3 hours; then, it is cooled to room temperature at a rate of 45-55℃ / h.

[0050] S8, Cleaning, Grinding and Polishing

[0051] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. First, degreasing is performed using a sodium hydroxide aqueous solution with a pH range of 7-9 and a solution temperature of 60-70℃. Then, acid washing is performed using sulfuric acid with a concentration of 100-130 g / L and a temperature ≤40℃. The acid solution contains Cu... 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the pressure is 30-50%, and the rotation speed is 1000-1500r / min. A hard grinding brush is used to remove the 4-8μm oxide layer from the surface of the copper strip; cleaning and drying are then performed in an oven at 65-70℃.

[0052] S9, medium rolling

[0053] The intermediate rolling processing rate is controlled at over 75%.

[0054] S10, Second Micro-oxidation Atmosphere Stepped Heat Treatment

[0055] The micro-oxidation atmosphere step heat treatment uses a mixed gas of 3-5% oxygen and the balance nitrogen. The heat treatment process is as follows: first, the alloy copper strip is heated to 300-320℃ at a heating rate of 75-85℃ / h and held at this first temperature for 2-3 hours; then, it is cooled to room temperature at a rate of 45-55℃ / h.

[0056] S11, Cleaning, Grinding and Polishing

[0057] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. First, degreasing is performed using a sodium hydroxide aqueous solution with a pH range of 7-9 and a solution temperature of 60-70℃. Then, acid washing is performed using sulfuric acid with a concentration of 100-130 g / L and a temperature ≤40℃. The acid solution contains Cu... 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the pressure is 30-50%, and the rotation speed is 1000-1500r / min. A hard grinding brush is used to remove the 4-8μm oxide layer from the surface of the copper strip; cleaning and drying are then performed in an oven at 65-70℃.

[0058] S12, Finished product rolling

[0059] The finished product processing rate is controlled at 14-18%.

[0060] S13, Cleaning, Grinding and Polishing

[0061] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. First, degreasing is performed using a sodium hydroxide aqueous solution with a pH range of 7-9 and a solution temperature of 60-70℃. Then, acid washing is performed using sulfuric acid with a concentration of 100-130 g / L and a temperature ≤40℃. The acid solution contains Cu... 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the pressure is 30-50%, and the rotation speed is 1000-1500r / min. A hard grinding brush is used to remove the 4-8μm oxide layer from the surface of the copper strip; cleaning and drying are then performed in an oven at 65-70℃.

[0062] S14, Straightening and Bending

[0063] During tension straightening, the straightening elongation is 0.2-0.3%, and the straightening unit tension is 25-35 kg / mm. 2 .

[0064] S15. Finished product slitting and packaging.

[0065] The technical solution and effects of the present invention will be illustrated below with specific embodiments.

[0066] The specific compositions of the copper alloy strips of Examples 1-4 and Comparative Examples 1-4 are shown in Table 2, and the key process parameters are shown in Table 3.

[0067] Example 1

[0068] The preparation steps of the copper alloy strip in this embodiment are as follows:

[0069] 1) Batching and smelting

[0070] Electrolytic copper is added to a smelting furnace and heated to a temperature of 1105℃. Copper-tellurium master alloy, copper-phosphorus master alloy, and copper-arsenic master alloy are added according to the specified proportions. After all the master alloys have melted, the temperature is held for 20 minutes, then lowered to 1085℃, and casting begins.

[0071] 2) Semi-continuous casting

[0072] Open the stopper rod and pour molten copper into the crystallizer. Then turn on the cooling water. When the molten copper level in the crystallizer reaches about two-thirds full, start the traction machine and begin casting at 24 mm / min. Turn on the vibration at a frequency of 64 times / min and an amplitude of 3.5 mm. Graphite powder is sprayed throughout the casting process. When the ingot reaches 0.5–1.0 meters, a steady-speed casting stage is reached, with the casting speed controlled at 135 mm / min and the primary cooling water flow rate controlled at 52 mm / min. 3 The water pressure is controlled at 0.47 MPa, the cooling water temperature at 28℃, and the outlet water temperature at 43℃. The casting specifications are 200*620mm*8000mm.

[0073] 3) Hot rolling + online β / α phase transformation heat treatment

[0074] The ingot heating temperature is 645℃, the holding time is 3 hours, the hot rolling start temperature is 625℃, the hot rolling rate is above 90%, and the hot rolling finish temperature is ensured to be 455℃, hot-rolled to a thickness of 15.5mm, and the width after hot rolling extension is 650±5mm. Within 10 minutes, the hot-rolled strip is coiled online and placed in the heat treatment furnace at the coiling point of the hot rolling process. The heat treatment furnace temperature is adjusted to 454℃ and held for 4 hours. Then, within 5 minutes of exiting the furnace, the entire coil is suspended into a water tank for water cooling to room temperature. After hot rolling and online β / α phase transformation heat treatment, the β phase ratio of the alloy microstructure is controlled to be less than 10%.

[0075] 4) Milling

[0076] The single-sided milling depth is 0.75mm.

[0077] 5) Rough rolling

[0078] Rough rolling to 1.2mm, with a processing rate of 91.43%.

[0079] 6) Trimming the edges

[0080] The single-sided shearing is 10mm, and the bandwidth after shearing is 630±0.5mm.

[0081] 7) First micro-oxidation atmosphere step heat treatment

[0082] The micro-oxidation atmosphere step heat treatment uses a mixed gas of 3.5% oxygen and the balance nitrogen. The heat treatment process is as follows: first, the alloy copper strip is heated to 305℃ at a heating rate of 80℃ / h and held at that temperature for 3 hours; then, it is heated to 365℃ at a heating rate of 60℃ / h and held at that temperature for 6 hours; finally, it is cooled to room temperature at a rate of 50℃ / h.

[0083] 8) Cleaning, grinding, and polishing

[0084] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. First, degreasing is performed using a sodium hydroxide aqueous solution with a pH range of 7.5 and a solution temperature of 70℃. Then, acid washing is performed using a sulfuric acid concentration of 110 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the reduction is 38%, and the rotation speed is 1450r / min. A 5μm oxide layer is removed from the surface of the copper strip using relatively hard grinding brushes; cleaning and drying are then performed in an oven at 70℃.

[0085] 9) Intermediate Rolling Mill

[0086] The material is rolled to 0.24mm, with a processing rate of 80%.

[0087] 10) Second micro-oxidation atmosphere step heat treatment

[0088] The micro-oxidation atmosphere step heat treatment uses a mixed gas of 3.5% oxygen and the balance nitrogen. The heat treatment process is as follows: first, the alloy copper strip is heated to 305℃ at a heating rate of 80℃ / h and held at that temperature for 3 hours; then, it is heated to 365℃ at a heating rate of 60℃ / h and held at that temperature for 6 hours; finally, it is cooled to room temperature at a rate of 50℃ / h.

[0089] 11) Cleaning, grinding, and polishing

[0090] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. Degreasing is performed first using a sodium hydroxide aqueous solution with a pH range of 7.6 and a solution temperature of 64℃. Acid washing is then performed using a sulfuric acid concentration of 108 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the reduction is 38%, and the rotation speed is 1460r / min. A relatively hard grinding brush is used to remove the 4.7μm oxide layer on the surface of the copper strip; cleaning and drying are performed in an oven at 68℃.

[0091] 12) Finished product rolling

[0092] The finished product is rolled to a thickness of 0.2 mm, with a finished product processing rate of 16.67%.

[0093] 13) Cleaning, grinding, and polishing

[0094] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. Degreasing is performed first using a sodium hydroxide aqueous solution with a pH range of 7.9 and a solution temperature of 68℃. Acid washing is then performed using a sulfuric acid concentration of 120 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the pressure is 40%, and the rotation speed is 1300r / min. A 5μm oxide layer is removed from the surface of the copper strip using a relatively hard grinding brush; cleaning and drying are then performed in an oven at 67℃.

[0095] 14) Straightening by bending

[0096] During tension straightening, the straightening elongation rate was 0.26%, and the straightening unit tension was 29 kg / mm. 2 .

[0097] 15) Finished product slitting and packaging.

[0098] Example 2

[0099] The preparation steps of the copper alloy strip in this embodiment are as follows:

[0100] 1) Batching and smelting

[0101] Electrolytic copper is added to a smelting furnace and heated to a temperature of 1114℃. Copper-tellurium master alloy, copper-phosphorus master alloy, and copper-arsenic master alloy are added according to the specified proportions. After all the master alloys have melted, the temperature is held for 20 minutes, then reduced to 1091℃, and casting begins.

[0102] 2) Semi-continuous casting

[0103] Open the stopper rod and pour molten copper into the crystallizer. Then turn on the cooling water. When the molten copper level in the crystallizer reaches about two-thirds full, start the traction machine and begin casting at 26 mm / min. Turn on the vibration at a frequency of 71 times / min and an amplitude of 4.3 mm. Graphite powder is sprayed throughout the casting process. When the ingot reaches 0.5–1.0 meters, a steady-speed casting stage is reached, with the casting speed controlled at 139 mm / min and the primary cooling water flow rate controlled at 56 mm / min. 3 The water pressure is controlled at 0.52 MPa, the cooling water temperature at 31℃, and the outlet water temperature at 48℃. The casting specifications are 200*620mm*8000mm.

[0104] 3) Hot rolling + online β / α phase transformation heat treatment

[0105] The ingot heating temperature is 653℃, the holding time is 2.7h, the hot rolling start temperature is 636℃, the hot rolling rate is above 90%, and the hot rolling finish temperature is ensured to be 464℃, hot rolling to a thickness of 15.2mm, and the width after hot rolling expansion is 650±5mm. Within 10 minutes, the hot-rolled strip is coiled online and placed in the heat treatment furnace at the coiling point of the hot rolling process. The heat treatment furnace temperature is adjusted to 455℃ and held for 3.8 hours. Then, within 5 minutes of exiting the furnace, the entire coil is suspended into a water tank for water cooling to room temperature. After hot rolling and online β / α phase transformation heat treatment, the β phase ratio of the alloy microstructure is controlled to be within 10%.

[0106] 4) Milling

[0107] The single-sided milling depth is 0.75mm.

[0108] 5) Rough rolling

[0109] Rough rolling to 1.0 mm, with a processing rate controlled at 92.7%.

[0110] 6) Trimming the edges

[0111] The single-sided shearing is 10mm, and the bandwidth after shearing is 630±0.5mm.

[0112] 7) First micro-oxidation atmosphere step heat treatment

[0113] The micro-oxidation atmosphere step heat treatment uses a mixed gas of 3.8% oxygen and the balance nitrogen. The heat treatment process is as follows: first, the alloy copper strip is heated to 307℃ at a heating rate of 80℃ / h and held at this first step for 2.8h; then, it is heated to 375℃ at a heating rate of 60℃ / h and held at this second step for 5.4h; finally, it is cooled to room temperature at a rate of 50℃ / h.

[0114] 8) Cleaning, grinding, and polishing

[0115] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. Degreasing is performed first using a sodium hydroxide aqueous solution with a pH range of 8.0 and a solution temperature of 66℃. Acid washing is then performed using a sulfuric acid concentration of 120 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the reduction is 44%, and the rotation speed is 1360r / min. A relatively hard grinding brush is used to remove the 4.8μm oxide layer on the surface of the copper strip; cleaning and drying are performed in an oven at 66℃.

[0116] 9) Intermediate Rolling Mill

[0117] The thickness was rolled to 0.215 mm, with a processing rate of 78.5%.

[0118] 10) Second micro-oxidation atmosphere step heat treatment

[0119] The micro-oxidation atmosphere step heat treatment uses a mixed gas of 3.8% oxygen and the balance nitrogen. The heat treatment process is as follows: first, the alloy copper strip is heated to 307℃ at a heating rate of 80℃ / h and held at this first step for 2.8h; then, it is heated to 375℃ at a heating rate of 60℃ / h and held at this second step for 5.4h; finally, it is cooled to room temperature at a rate of 50℃ / h.

[0120] 11) Cleaning, grinding, and polishing

[0121] The cleaning, grinding, and polishing process is as follows: degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. First, degreasing is performed using a sodium hydroxide aqueous solution with a pH range of 8.1 and a solution temperature of 65℃. Then, acid washing is performed using a sulfuric acid concentration of 121 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the reduction is 41%, and the rotation speed is 1290r / min. A relatively hard grinding brush is used to remove the 5.2μm oxide layer on the surface of the copper strip; cleaning and drying are performed in an oven at 68℃.

[0122] 12) Finished product rolling

[0123] The finished product is rolled to 0.18mm, with a processing rate of 16.28%.

[0124] 13) Cleaning, grinding, and polishing

[0125] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. Degreasing is performed first using a sodium hydroxide aqueous solution with a pH range of 8.4 and a solution temperature of 68℃. Acid washing is then performed using a sulfuric acid concentration of 117 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the reduction is 39%, and the rotation speed is 1420r / min. A relatively hard grinding brush is used to remove the 6.1μm oxide layer on the surface of the copper strip; cleaning and drying are performed in an oven at 67℃.

[0126] 14) Straightening by bending

[0127] During tension straightening, the straightening elongation rate was 0.27%, and the straightening unit tension was 31 kg / mm. 2 .

[0128] 15) Finished products are slitting and packaging.

[0129] Example 3

[0130] The preparation steps of the copper alloy strip in this embodiment are as follows:

[0131] 1) Batching and smelting

[0132] Electrolytic copper is added to a smelting furnace and heated to a temperature of 1115℃. Copper-tellurium master alloy, copper-phosphorus master alloy, and copper-arsenic master alloy are added according to the specified proportions. After all the master alloys have melted, the temperature is held for 20 minutes, then lowered to 1097℃, and casting begins.

[0133] 2) Semi-continuous casting

[0134] Open the stopper rod and pour molten copper into the crystallizer. Then turn on the cooling water. When the molten copper level in the crystallizer reaches about two-thirds full, start the traction machine and begin casting at 28 mm / min. Turn on the vibration at a frequency of 77 times / min and an amplitude of 4.8 mm. Graphite powder is sprayed throughout the casting process. When the ingot reaches 0.5–1.0 meters, a steady-speed casting stage is reached, with the casting speed controlled at 146 mm / min and the primary cooling water flow rate controlled at 58 mm / min. 3 The water pressure is controlled at 0.46 MPa, the cooling water temperature at 32℃, and the outlet water temperature at 46℃. The casting specifications are 200*620mm*8000mm.

[0135] 3) Hot rolling + online β / α phase transformation heat treatment

[0136] The ingot heating temperature is 665℃, the holding time is 2.8h, the hot rolling start temperature is 640℃, the hot rolling rate is above 90%, and the hot rolling finish temperature is ensured to be 462℃, hot rolling to a thickness of 15mm, and the width after hot rolling expansion is 650±5mm. Within 10 minutes, the hot-rolled strip is coiled online and placed in the heat treatment furnace at the coiling point of the hot rolling process. The heat treatment furnace temperature is adjusted to 458℃ and held for 3.5 hours. Then, within 5 minutes of exiting the furnace, the entire coil is suspended into a water tank for water cooling to room temperature. After hot rolling and online β / α phase transformation heat treatment, the β phase ratio of the alloy microstructure is controlled to be less than 10%.

[0137] 4) Milling

[0138] The single-sided milling depth is 0.75mm.

[0139] 5) Rough rolling

[0140] Rough rolling to 0.95mm, with a processing rate of 93.66%.

[0141] 6) Trimming the edges

[0142] The single-sided shearing is 10mm, and the bandwidth after shearing is 630±0.5mm.

[0143] 7) First micro-oxidation atmosphere step heat treatment

[0144] The micro-oxidation atmosphere step heat treatment uses a mixed gas of 3.6% oxygen and the balance nitrogen. The heat treatment process is as follows: first, the alloy copper strip is heated to 316℃ at a heating rate of 80℃ / h and held at this first step for 2.3h; then, it is heated to 384℃ at a heating rate of 60℃ / h and held at this second step for 4.6h; finally, it is cooled to room temperature at a rate of 50℃ / h.

[0145] 8) Cleaning, grinding, and polishing

[0146] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. First, degreasing is performed using a sodium hydroxide aqueous solution with a pH range of 8.6 and a solution temperature of 68℃. Then, acid washing is performed using a sulfuric acid concentration of 123 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the reduction is 47%, and the rotation speed is 1380r / min. A relatively hard grinding brush is used to remove the 6.1μm oxide layer on the surface of the copper strip; cleaning and drying are performed in an oven at 68℃.

[0147] 9) Intermediate Rolling Mill

[0148] The thickness was rolled to 0.18 mm, with a processing rate of 81.05%.

[0149] 10) Second micro-oxidation atmosphere step heat treatment

[0150] The micro-oxidation atmosphere step heat treatment uses a mixed gas of 3.6% oxygen and the balance nitrogen. The heat treatment process is as follows: first, the alloy copper strip is heated to 316℃ at a heating rate of 80℃ / h and held at this first step for 2.3h; then, it is heated to 384℃ at a heating rate of 60℃ / h and held at this second step for 4.6h; finally, it is cooled to room temperature at a rate of 50℃ / h.

[0151] 11) Cleaning, grinding, and polishing

[0152] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. First, degreasing is performed using a sodium hydroxide aqueous solution with a pH range of 8.4 and a solution temperature of 67℃. Then, acid washing is performed using a sulfuric acid concentration of 126 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the reduction is 45%, and the rotation speed is 1470r / min. A relatively hard grinding brush is used to remove the 5.6μm oxide layer on the surface of the copper strip; cleaning and drying are performed in an oven at 66℃.

[0153] 12) Finished product rolling

[0154] The finished product is rolled to a thickness of 0.15 mm, with a processing rate of 16.67%.

[0155] 13) Cleaning, grinding, and polishing

[0156] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. Degreasing is performed first using a sodium hydroxide aqueous solution with a pH range of 8.2 and a solution temperature of 63℃. Acid washing is then performed using a sulfuric acid concentration of 114 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the reduction is 46%, and the rotation speed is 1420r / min. A relatively hard grinding brush is used to remove the 5.0μm oxide layer from the surface of the copper strip; cleaning and drying are performed in an oven at 67℃.

[0157] 14) Straightening by bending

[0158] During tension straightening, the straightening elongation rate is 0.28%, and the straightening unit tension is 32 kg / mm. 2 .

[0159] 15) Finished products are slitting and packaging.

[0160] Example 4

[0161] The preparation steps of the copper alloy strip in this embodiment are as follows:

[0162] 1) Batching and smelting

[0163] Electrolytic copper is added to a smelting furnace and heated to a temperature of 1109℃. Copper-tellurium master alloy, copper-phosphorus master alloy, and copper-arsenic master alloy are added according to the specified proportions. After all the master alloys have melted, the mixture is held at that temperature for 20 minutes, then the temperature is lowered to 1092℃, and casting begins.

[0164] 2) Semi-continuous casting

[0165] Open the stopper rod and pour molten copper into the crystallizer. Then turn on the cooling water. When the molten copper level in the crystallizer reaches about two-thirds full, start the traction machine and begin casting at 27 mm / min. Turn on the vibration at a frequency of 78 times / min and an amplitude of 4.5 mm. Graphite powder is sprayed throughout the casting process. When the ingot reaches 0.5-1.0 meters, a steady-speed casting stage is reached, with the casting speed controlled at 135 mm / min and the primary cooling water flow rate controlled at 54 mm / min. 3 The water pressure is controlled at 0.48 MPa, the cooling water temperature at 29℃, and the outlet water temperature at 44℃. The casting specifications are 200*620mm*8000mm.

[0166] 3) Hot rolling + online β / α phase transformation heat treatment

[0167] The ingot heating temperature is 660℃, the holding time is 2.5h, the hot rolling start temperature is 642℃, the hot rolling rate is above 90%, and the hot rolling finish temperature is ensured to be 477℃, hot rolling to a thickness of 14.5mm, and the width after hot rolling expansion is 650±5mm. Within 10 minutes, the hot-rolled strip is coiled online and placed in the heat treatment furnace at the coiling point of the hot rolling process. The heat treatment furnace temperature is adjusted to 453℃ and held for 3.9 hours. Then, within 5 minutes of exiting the furnace, the entire coil is suspended into a water tank for water cooling to room temperature. After hot rolling and online β / α phase transformation heat treatment, the β phase ratio of the alloy microstructure is controlled to be within 10%.

[0168] 4) Milling

[0169] The single-sided milling depth is 0.75mm.

[0170] 5) Rough rolling

[0171] Rough rolling to 0.8 mm, with a processing rate of 93.85%.

[0172] 6) Trimming the edges

[0173] The single-sided shearing is 10mm, and the bandwidth after shearing is 630±0.5mm.

[0174] 7) First micro-oxidation atmosphere step heat treatment

[0175] The micro-oxidation atmosphere step heat treatment uses a mixed gas of 3.8% oxygen and the balance nitrogen. The heat treatment process is as follows: first, the alloy copper strip is heated to 310℃ at a heating rate of 80℃ / h and held at this first step for 2.8h; then, it is heated to 378℃ at a heating rate of 60℃ / h and held at this second step for 5.0h; finally, it is cooled to room temperature at a rate of 50℃ / h.

[0176] 8) Cleaning, grinding, and polishing

[0177] The cleaning, grinding, and polishing process is as follows: degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. First, degreasing is performed using a sodium hydroxide aqueous solution with a pH range of 8.7 and a solution temperature of 62℃. Then, acid washing is performed using a sulfuric acid concentration of 108 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the pressure is 40%, and the rotation speed is 1380r / min. A relatively hard grinding brush is used to remove the 4.5μm oxide layer on the surface of the copper strip; cleaning and drying are performed in an oven at 67℃.

[0178] 9) Intermediate Rolling Mill

[0179] The material was rolled to 0.144 mm, with a processing rate of 82%.

[0180] 10) Second micro-oxidation atmosphere step heat treatment

[0181] The micro-oxidation atmosphere step heat treatment uses a mixed gas of 3.8% oxygen and the balance nitrogen. The heat treatment process is as follows: first, the alloy copper strip is heated to 310℃ at a heating rate of 80℃ / h and held at this first step for 2.8h; then, it is heated to 378℃ at a heating rate of 60℃ / h and held at this second step for 5.0h; finally, it is cooled to room temperature at a rate of 50℃ / h.

[0182] 11) Cleaning, grinding, and polishing

[0183] The cleaning, grinding, and polishing process is as follows: degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. First, degreasing is performed using a sodium hydroxide aqueous solution with a pH range of 8.3 and a solution temperature of 64℃. Then, acid washing is performed using a sulfuric acid concentration of 115 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the pressure reduction is 45%, and the rotation speed is 1390r / min. A relatively hard grinding brush is used to remove the 5.3μm oxide layer on the surface of the copper strip; cleaning and drying are performed in an oven at 67℃.

[0184] 12) Finished product rolling

[0185] The finished product is rolled to a thickness of 0.12 mm. The processing rate is 16.67%.

[0186] 13) Cleaning, grinding, and polishing

[0187] The cleaning, grinding, and polishing process consists of degreasing → water washing → acid washing → hot water washing → grinding and polishing → passivation → drying. First, degreasing is performed using a sodium hydroxide aqueous solution with a pH range of 8.7 and a solution temperature of 68℃. Then, acid washing is performed using a sulfuric acid concentration of 125 g / L at a temperature ≤40℃, with Cu in the acid solution. 2+ ≤1.2g / l; The grinding brushes used in the grinding process are made of non-woven fabric + silicon carbide. The first pair of grinding brushes is 2000 mesh, and the second pair is 3000 mesh. The grinding brush radius is 400-500mm, the reduction is 46%, and the rotation speed is 1350r / min. A relatively hard grinding brush is used to remove the 5.8μm oxide layer on the surface of the copper strip; cleaning and drying are performed in an oven at 69℃.

[0188] 14) Straightening by bending

[0189] During tension straightening, the straightening elongation rate was 0.28%, and the straightening unit tension was 34 kg / mm. 2 .

[0190] 15) Finished product slitting and packaging.

[0191] Comparative Example 1

[0192] The preparation steps of the copper alloy strip in this comparative example differ from those in Example 4 in that trace amounts of alloying elements such as Te, P, and As were not added.

[0193] Comparative Example 2

[0194] The preparation steps of the copper alloy strip in this comparative example differ from those in Example 4 in that step 3) only involves hot rolling without online β / α phase transformation heat treatment. Specifically, the hot rolling process in step 3) is as follows: ingot heating temperature is 660℃, holding time is 2.5h, hot rolling start temperature is 642℃, hot rolling yield is above 90%, and the final hot rolling temperature is ensured to be 477℃, hot rolling to a thickness of 14.5mm, and the width after hot rolling expansion is 650±5mm.

[0195] Comparative Example 3

[0196] The preparation steps of the copper alloy strip in this comparative example differ from those in Example 4 in that: the heat treatment in steps 7) and 10) is carried out in a reducing atmosphere of 75% H2 + 25% N2, and the annealing process is to heat to 378°C at a heating rate of 60°C / h and hold for 5.0h, and finally cool down to room temperature at a rate of 50°C / h.

[0197] Comparative Example 4

[0198] The preparation steps of the copper alloy strip in this comparative example differ from those in Example 4 in that the grinding and polishing brushes used in steps 8), 11), and 13) are made of non-woven fabric and are free of silicon carbide.

[0199] Table 2 Chemical composition (wt%) of copper alloy strips from various embodiments and comparative examples of the present invention.

[0200] Example 1 61.20 0.008 0.013 0.006 0.0008 0.0007 0.0009 0.0007 0.0045 0.0038 margin Example 2 60.60 0.009 0.016 0.008 0.0007 0.0006 0.0008 0.0006 0.0041 0.0035 margin Example 3 59.50 0.012 0.018 0.009 0.0004 0.0003 0.0005 0.0004 0.0032 0.0028 margin Example 4 60.25 0.01 0.015 0.0075 0.0005 0.0004 0.0006 0.0005 0.0035 0.0031 margin Comparative Example 1 60.25 - - - 0.0005 0.0004 0.0006 0.0005 0.0035 0.0031 margin Comparative Example 2 60.25 0.01 0.015 0.0075 0.0005 0.0004 0.0006 0.0005 0.0035 0.0031 margin Comparative Example 3 60.25 0.01 0.015 0.0075 0.0005 0.0004 0.0006 0.0005 0.0035 0.0031 margin Comparative Example 4 60.25 0.01 0.015 0.0075 0.0005 0.0004 0.0006 0.0005 0.0035 0.0031 margin

[0201] Table 3 Key process parameters control for each embodiment and comparative example of the present invention

[0202]

[0203] The mechanical properties, electrical conductivity, and microstructure of the copper alloy strips prepared in Examples 1-4 and Comparative Examples 1-4 were tested, and the results are shown in Table 4. The test methods are as follows:

[0204] Composition analysis: The laboratory direct-reading spectrometer was used to perform composition analysis according to the standard "YS / T 482-2022 Analysis Methods for Copper and Copper Alloys: Spark Discharge Atomic Emission Spectrometry".

[0205] Metallographic grain size test: The grain size in the photographs acquired using a 1000x metallographic microscope was tested according to the intercept method in GB / T 6394-2007, "Method for Determination of Average Grain Size of Metals". The sample width was 10 mm and the length was 10 mm.

[0206] β-phase ratio test: The β-phase in the alloy photographs acquired using a 100x metallographic microscope was tested according to the β-phase test method in "YS / T 347-2020 Method for Determination of Average Grain Size of Copper and Copper Alloys". The sample width was 10 mm and the length was 10 mm.

[0207] Zinc-removed layer pitting test: Metallographic testing was performed using a scanning electron microscope according to the "General Rules for Measurement Methods of Scanning Electron Microscopes with Lengths in the Micrometer Scale" (GB / T 16594-2008). The sample width was 10 mm and the length was 10 mm.

[0208] Copper powder removal test: A high-speed stamping machine was used to produce copper powder at a stamping speed of 1200 times / min. After stamping for ten minutes, the machine was stopped to observe the copper powder adhering to the surface of the stamping die.

[0209] Mechanical property testing: The room temperature tensile test was conducted on an electronic universal mechanical property testing machine in accordance with GB / T 228.1-2010 Metallic materials, tensile testing - Part 1: Room temperature test method. A 20 mm wide specimen with a head was used, and the tensile speed was 5 mm / min.

[0210] Examples 1-4 show that the copper alloy strip prepared according to the embodiments of the present invention has a thickness of 0.1-0.25 mm, a hardness of 140-160 HV, a tensile strength of 470-530 MPa, an elongation of >25%, a roughness Ra <0.12 μm, an average grain size of 4-8 μm, a β phase ratio of <10%, and does not crack when bent at 180° R / T=0.5 in the Goodway direction and at 180° R / T=1 in the Badway direction. It does not lose copper powder when stamped at high speed of 800-1200 m / min, and has good electroplating performance, meeting the requirements for high-zinc brass strip for LED lamp lead brackets.

[0211] Table 4. Tissue structure and performance of various embodiments and comparative examples of the present invention.

[0212]

[0213] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A copper alloy, characterized in that, The copper alloy comprises the following components by mass percentage: Cu: 59.0-61.5 wt%, Te: 0.005-0.015 wt%, P: 0.01-0.02 wt%, As: 0.005-0.01 wt%, Si < 0.001 wt%, Al < 0.001 wt%, Sn < 0.001 wt%, Mg < 0.001 wt%, Fe < 0.005 wt%, Pb < 0.005 wt%, and Zn as the balance; wherein the area ratio of the β phase in the copper alloy is less than 10%. The method for preparing the copper alloy includes the following steps: batching and smelting → semi-continuous casting → hot rolling + online β / α phase transformation heat treatment → rough rolling cold working → first micro-oxidation atmosphere step heat treatment → cleaning, grinding and polishing → intermediate rolling cold working → second micro-oxidation atmosphere step heat treatment → cleaning, grinding and polishing → finished product rolling → cleaning, grinding and polishing. In the hot rolling + online β / α phase transformation heat treatment process, the initial rolling temperature is controlled between 620-650℃, the final rolling temperature is controlled between 450-480℃, and after hot rolling, the hot-rolled strip is coiled online within 10 minutes and placed in a heat treatment furnace at a temperature of 450-460℃ for 3-4 hours. Within 5 minutes of exiting the furnace, the entire coil is hoisted into a water tank for water cooling to room temperature. The process of the first and second micro-oxidation atmosphere step heat treatments is as follows: The alloy copper strip is first heated to 300-320℃ at a heating rate of 75-85℃ / h in a micro-oxidation atmosphere and held for 2-3 hours; then heated to 360-390℃ at a heating rate of 55-65℃ / h and held for 4-6 hours. The micro-oxidation atmosphere is a mixture of oxygen and nitrogen, with oxygen accounting for 3-5% of the volume in the mixture. The grinding brush used in the cleaning, grinding and polishing process is made of non-woven fabric and silicon carbide.

2. The copper alloy according to claim 1, characterized in that, The average grain size of the copper alloy is 4-8 μm.

3. The copper alloy according to claim 1 or 2, characterized in that, The copper alloy has a surface roughness Ra < 0.12 μm, and does not crack when bent at 180° R / T = 0.5 in the Goodway direction and at 180° R / T = 1 in the Badway direction.

4. The copper alloy according to claim 1, characterized in that, The processing rate of the rough rolling cold working is ≥90%.

5. The copper alloy according to claim 1, characterized in that, The processing rate of the intermediate rolling cold working is ≥75%.

6. The copper alloy according to claim 1, characterized in that, The finished product rolling rate is controlled at 14-18%.

7. The copper alloy according to claim 1, characterized in that, The first pair of grinding brushes is 2000 mesh, the second pair of grinding brushes is 3000 mesh, the grinding brush radius is 400-500mm, the pressure is 30-50%, and the rotation speed is 1000-1500r / min.

8. The application of the copper alloy according to any one of claims 1-7 in LED lamp lead brackets.

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