Cu95Zn4.8Sn0.2 copper alloy and strip preparation method thereof

Abstract

The present application relates to a kind of Cu95Zn4.8Sn0.2 copper alloy and its plate strip preparation method, copper alloy composition is according to mass percentage, including Cu:94.5~95.5%, Zn:4.34~5.34%, Ce:0.01~0.04%, Sr:0.01~0.04%, Sn:0.04~0.18%;Its copper alloy plate strip preparation method steps include batching, melting, ingot heating, hot rolling, pre-precision rolling, pre-precision rolling annealing, finished product rolling, finished product heat treatment, cleaning and passivation.The present application can greatly improve the elongation of material while ensuring the tensile strength, electrical conductivity, thermal conductivity of H95 copper alloy, improve the bending performance of material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of non-ferrous metal processing, and particularly relates to a Cu95Zn4.8Sn0.2 copper alloy and a preparation method of plate strip material thereof. BACKGROUND

[0002] With the diversification of high-end automobile functions and the universal application of electronic control technology, the number and power of automobile circuits have significantly increased, and automobile connectors have become thicker and heavier. In order to improve the reliability and durability of connectors and play a greater function, the use of high-strength, high-elongation and high-conductivity materials has become an important choice in the design process of automobile connectors.

[0003] As a standard configuration of smart phones, the performance requirements of mobile phone camera supports are gradually improved, and the material is required to have high strength, excellent plasticity, toughness, conductivity and thermal conductivity.

[0004] At present, the commonly used low-copper brass alloy material of connectors and mobile phone camera supports has the characteristics of large heat generation and large power consumption, and the comprehensive performance cannot meet the needs of high-end customers. Compared with the connector made of low-copper brass alloy material (H65) of the same specification, H95 as a material of the connector has 1 times higher conductivity and is more energy-saving, which is a microcosm of the transition from high-speed industrialization to high-quality industrialization in the material industry. H95 material has become an important choice for connector customers due to its high comprehensive performance, but the elongation rate and bending performance of ordinary H95 material cannot meet the customer's demand under a certain strength state. SUMMARY

[0005] The purpose of the application is to provide a Cu95Zn4.8Sn0.2 copper alloy and a preparation method of plate strip material thereof, which greatly improves the elongation rate and bending performance of the material under the premise of ensuring the strength and conductivity of the copper alloy.

[0006] In order to achieve the above purpose, the technical scheme adopted by the application is as follows: a Cu95Zn4.8Sn0.2 copper alloy, the composition of which comprises, in terms of mass percentage, Cu: 94.5-95.5%, Zn: 4.34-5.34%, Ce: 0.01-0.04%, Sr: 0.01-0.04% and Sn: 0.04-0.18%.

[0007] The finished product Cu95Zn4.8Sn0.2 has a transverse grain size of 0.010-0.030mm, and more than 90% of the grains are in the range of 0.015-0.025mm.

[0008] The application also provides a preparation method of Cu95Zn4.8Sn0.2 copper alloy plate strip material, comprising the following steps:

[0009] Step one, according to the alloy composition described above, ingredients are prepared;

[0010] Step two, the raw materials of step one are smelted, wherein the added form of Zn is zinc ingot, the added form of Ce and Sr is Cu-Ce and Cu-Sr intermediate alloy, and the added form of Sn is Sn block;

[0011] Step three, casting is carried out when the melt temperature is 1160-1210℃, the casting speed is 4-10m / h, and borax is used as flux to cover the melt in the crystallizer during casting;

[0012] Step four, the sawed cast ingot is heated, and the heating temperature is 800-820℃;

[0013] Step five, the cast ingot is carried out on the hot rolling equipment, the total processing rate of the hot rolling strip is 88%-98%, the last pass of hot rolling is carried out laminar cooling treatment, and the material is required to be cooled to below 50℃ within 60 seconds;

[0014] Step six, the hot-rolled strip is milled;

[0015] Step seven, the milled strip is pre-rolled;

[0016] Step eight, the pre-rolled strip is carried out intermediate annealing in an annealing furnace, the annealing temperature is 430-530℃, the annealing time is 6-9 hours, and atmosphere protection is adopted in the annealing;

[0017] Step nine, the pre-rolled and annealed strip is rolled to a finished strip, the last pass adopts a small processing rate of 10%-15% and a constant tension of 600-800Kg;

[0018] Step ten, the finished plate strip material rolled in the above step is carried out heat treatment, the heat treatment temperature is 200-320℃, the heat treatment time is 2-6 hours, and atmosphere protection is adopted in the heat treatment;

[0019] Step eleven, the heat-treated finished plate strip material is cleaned and passivated to obtain the prepared Cu95Zn4.8Sn0.2 copper alloy plate strip material.

[0020] Specifically, in step eight and step ten, 75% high hydrogen atmosphere is used for protection.

[0021] Specifically, the passivation solution used in step eleven is deionized water matched to form a 1-3‰ benzene propyl triazole solution.

[0022] Specifically, the passivation treatment temperature in step eleven is 60-85℃.

[0023] The principle of the present application is analyzed as follows:

[0024] 1. Ingot production, adding rare earth elements Ce, Sr to the material for modification treatment, adding trace elements Sn for fine grain strengthening;

[0025] Specifically, the effect of adding Sn: can refine copper grains, delay the recrystallization process of copper, improve its strength and hardness;

[0026] The effect of adding Ce: solid solution in brass, improve the alloy strength, improve the processing performance of Cu95Zn4.8Sn0.2 material;

[0027] The effect of adding Sr: the solid solubility of strontium is very small, which is easy to gather on the grain boundary, hinder the grain growth, reduce the interface energy, promote the nucleation, play the role of refining the grain, improve the material strength, hardness, further improve the plasticity and processing forming of Cu95Zn4.8Sn0.2 material;

[0028] 2. In the hot rolling process, online laminar cooling is carried out, which requires that the material is cooled to below 50℃ within 60 seconds, and the grain size of Cu95Zn4.8Sn0.2 material after hot rolling is controlled to be not more than 0.045mm; Because the strip temperature is 650-670℃ when the hot rolling process is completed, in order to avoid the growth of strip grains, it is necessary to change the cooling method of bubble water and use laminar cooling method to rapidly reduce the strip temperature and avoid grain growth; Controlling the grain size not more than 0.045mm is based on the genetic characteristics of grain size, only by controlling the grain size of the material after hot rolling, the finished grain size of the strip material can be controlled, and the elongation and bending performance of the material can be controlled.

[0029] The beneficial effects of the present application are: the copper alloy material proposed in the present application greatly improves the elongation and bending performance of the material while ensuring the tensile strength, electrical conductivity and thermal conductivity.

[0030] Compared with ordinary H95 copper alloy, the present application improves the elongation of the material by more than 3 times while ensuring the material strength ≥400Mpa and the electrical conductivity ≥56%; the bending performance is improved from R / T=2.0 bending qualified of ordinary H95 material to R / T=0.5 bending qualified. DETAILED DESCRIPTION

[0031] The present application will be further described in detail below in conjunction with examples, but it is not as the basis for any limitation on the invention.

[0032] Example 1: produce a Cu95Zn4.8Sn0.2 copper alloy strip with a specification of 2.5x600mm, which is used for connector products of new energy vehicles, has good comprehensive performance, bending performance meets customer requirements, and has high electrical conductivity.

[0033] The technical requirements for copper plates are as follows:

[0034] Grade: Cu95Zn4.8Sn0.2

[0035] Copper strip specifications: 2.5×600mm

[0036] State: Hard state (Y) / Very hard state (SH)

[0037] Performance requirements: Rm≥400 MPa; elongation≥6%; R / T=1.0, 90-degree bending qualified.

[0038] Tolerance requirements: thickness tolerance ±0.03mm, width tolerance ±2mm.

[0039] The preparation method is as follows:

[0040] (1) Ingredients: Cu: 95.2%, Zn: 4.67%, Ce: 0.03%, Sr: 0.02%, Sn: 0.08% by mass percentage;

[0041] (2) Smelting: After electrolytic copper is added to the induction furnace and melted, zinc ingots are added. After all the zinc is melted, Cu-Ce, Cu-Sr master alloys and Sn blocks are added.

[0042] (3) Casting: When the melt temperature is 1160~1210℃, a semi-continuous casting machine and a copper sleeve crystallizer are used for casting. The casting speed is 4~10 m / h. Borax is used as a flux to cover the melt in the crystallizer during casting.

[0043] Before the converter, the chemical composition of the melt in the smelting furnace is tested and analyzed, and during casting, the melt in the holding furnace is sampled and analyzed.

[0044] (4) Sawing: Sawing the ingots to the required length on a saw;

[0045] (5) Ingot heating: The ingot is heated by a walking beam furnace at a temperature of 800-820℃;

[0046] (6) Hot rolling: The ingot is hot rolled on a hot rolling equipment. The total processing rate of the hot rolled strip is 88% to 93%. The last pass of hot rolling is laminar flow cooling treatment, which requires the material to be cooled to below 50°C within 60 seconds.

[0047] (7) Milling: Milling the blank surface on a double-sided milling machine;

[0048] (8) Pre-finish rolling: The strip after milling is pre-finish rolled on the primary rolling mill;

[0049] (9) pre-precise annealing: annealing the pre-precise rolled strip in the annealing furnace, adopting cover furnace annealing, annealing temperature 430-510℃, annealing time 6-9 hours; using 75% high hydrogen atmosphere for protection in annealing;

[0050] (10) finished product rolling: rolling the pre-precise annealed strip to finished product strip by rolling mill, using small processing rate 10%-15% and constant tension 600-800 Kg in the last pass, controlling thickness tolerance and plate shape, using vacuum suction device in the last pass;

[0051] (11) finished product heat treatment: adopting cover furnace heat treatment, heat treatment temperature 200-320℃, heat treatment time 2-6 hours; using 75% high hydrogen atmosphere for protection in heat treatment;

[0052] (12) finished product cleaning and passivation: using passivation liquid to prevent strip corrosion and discoloration, passivation liquid is prepared by deionized water to be 1-3‰ benzene propyl triazole solution, working temperature is maintained at 60-85℃;

[0053] (13) finished product shearing: shearing according to customer's requirements;

[0054] (14) packaging and warehousing: after the finished product strip is inspected and qualified, it is packaged and warehoused.

[0055] The Cu95Zn4.8Sn0.2 finished product prepared in the embodiment has transverse grain size between 0.010-0.030mm, and the grain size between 0.015-0.025mm accounts for more than 90%. Because the smaller the grain size is, the more the grain boundaries are, and the crystal arrangement at many grain boundaries is very irregular, the crystal faces are staggered and bite each other, enhancing the binding force between metals, therefore, the elongation and bending performance of the product are better, the elongation of the material prepared in the embodiment is greatly improved to 7.0%-10.5%, and the 90° bending performance is greatly improved.

[0056] Example 2: producing a Cu95Zn4.8Sn0.2 copper alloy strip with a specification of 3.9x300mm, which is used for mobile phone camera support product, has good comprehensive performance and strength, and satisfies the customer in bending performance; the material does not deform after processing, the thinnest part of the material is 0.35mm; and the conductivity is relatively high.

[0057] The technical requirements of the copper plate are as follows:

[0058] Brand: Cu95Zn4.8Sn0.2

[0059] Copper strip specification: 3.9x300mm

[0060] State: hard state (Y) / super hard state (SH)

[0061] Performance requirements: Rm≥400 MPa; elongation ≥6%; R / T = 1.0, 90-degree bending qualified.

[0062] Tolerance requirements: thickness tolerance ± 0.03mm, width tolerance ± 1.5mm.

[0063] The preparation method is as follows:

[0064] (1) batching: according to the mass percentage, Cu: 94.9%, Zn: 4.90%, Ce: 0.03%, Sr: 0.03%, Sn: 0.14%;

[0065] (2) smelting: after melting the electrolytic copper in the induction furnace, add zinc ingot, after completely melting, add Cu-Ce, Cu-Sr intermediate alloy, Sn block;

[0066] (3) casting: when the melt temperature is 1160-1210℃, use semi-continuous casting machine, copper sleeve crystallizer for casting, casting speed 4-10m / h, use borax as flux to cover the melt in the crystallizer during casting;

[0067] Note: before the converter, detect and analyze the chemical composition of the melt in the smelting furnace, sample and analyze the melt in the holding furnace during casting;

[0068] (4) sawing: saw the cast ingot according to the required length on the sawing bed;

[0069] (5) cast ingot heating: cast ingot heating by step type heating furnace, heating temperature 800-820℃;

[0070] (6) hot rolling: cast ingot breakdown hot rolling on hot rolling equipment, hot rolling strip total processing rate 93%-98%, the last pass of hot rolling is laminar cooling treatment, the material is required to be cooled to below 50℃ within 60 seconds;

[0071] (7) face milling: face milling of the strip on the double-face milling machine;

[0072] (8) pre-finishing rolling: pre-finishing rolling of the milled strip on the blooming mill;

[0073] (9) pre-finishing rolling annealing: intermediate annealing of the pre-finishing rolled strip on the annealing furnace, using cover type furnace annealing, annealing temperature 430-530℃, annealing time 6-9 hours; using 75% high hydrogen atmosphere for protection during annealing;

[0074] (10) finished product rolling: finishing rolling of the pre-finishing annealed strip to finished product strip using the rolling mill, the last pass uses small processing rate 10%-15% and constant tension 600-800Kg rolling, controls thickness tolerance and plate shape, uses emulsion removal device in the last pass.

[0075] (11) Product heat treatment: cover furnace heat treatment, heat treatment temperature 200-320℃, heat treatment time 2-6 hours; high hydrogen atmosphere of 75% is used for protection in heat treatment;

[0076] (12) Product cleaning and passivation: passivation liquid is used to prevent strip corrosion discoloration, passivation liquid is prepared by deionized water to become 1-3‰ benzene propyl triazole solution, working temperature is maintained at 60-85℃;

[0077] (13) Product shearing: shearing is carried out according to customer's requirements;

[0078] (14) Packaging and warehousing: after product strip is tested and qualified, it is packaged and warehoused.

[0079] The Cu95Zn4.8Sn0.2 product prepared in the embodiment has a transverse grain size of 0.010-0.030mm, more than 90% of the grains are in the range of 0.015-0.025mm, the material elongation is greatly improved to 7.0%-10.5%, and the 90° bending performance is greatly improved.

[0080] Example 3: In this embodiment, the process described in Example 1 is used on the basis of Example 1, except that the copper alloy composition is different, and in the batching, the mass percentage of Cu is 94.6%, Zn is 5.30%, Ce is 0.01%, Sr is 0.01%, and Sn is 0.08%.

[0081] Example 4: In this embodiment, the process described in Example 1 is used on the basis of Example 1, except that the copper alloy composition is different, and in the batching, the mass percentage of Cu is 95.5%, Zn is 4.35%, Ce is 0.04%, Sr is 0.01%, and Sn is 0.1%.

[0082] Example 5: In this embodiment, the process described in Example 2 is used on the basis of Example 2, except that the copper alloy composition is different, and in the batching, the mass percentage of Cu is 95%, Zn is 4.76%, Ce is 0.02%, Sr is 0.04%, and Sn is 0.18%.

[0083] Example 6: In this embodiment, the process described in Example 2 is used on the basis of Example 2, except that the copper alloy composition is different, and in the batching, the mass percentage of Cu is 95.3%, Zn is 4.57%, Ce is 0.04%, Sr is 0.04%, and Sn is 0.05%.

[0084] Comparative Example: The Cu95Zn4.8Sn0.2 copper alloy strip prepared in Example 1 and the common H95 copper alloy strip were tested for performance at the same thickness, and the comparison results are shown in the following table.

[0085] Table 1 Comparison results of material performance test

[0086]

[0087] As shown in the above table, compared with the existing common H95 copper alloy, the material strength ≥ 400 MPa and the electrical conductivity ≥ 56% are ensured, the material elongation is increased by more than 3 times, and the bending performance of the material is improved, the R / T of the common H95 material is increased from 2.0 to 0.5.

[0088] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it. Those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced by equivalents according to the above examples, and any modification or equivalent replacement without departing from the spirit and scope of the present application is within the protection scope of the claims.

Claims

1. A copper alloy, characterized in that: The product is composed of the following components by mass percentage: Cu: 94.5–95.5%, Zn: 4.34–5.34%, Ce: 0.01–0.04%, Sr: 0.01–0.04%, Sn: 0.04–0.18%; the finished product has a transverse grain size between 0.010 and 0.030 mm, with more than 90% of the grains having a grain size between 0.015 and 0.025 mm. The preparation steps of the copper alloy include batching, smelting, casting, heating, hot rolling, milling, pre-finish rolling, intermediate annealing, finish rolling, heat treatment of finished product, as well as cleaning and passivation. In the hot rolling process, the total processing rate of the hot-rolled strip is 88% to 98%. The last pass of hot rolling is subjected to laminar flow cooling treatment, which requires the material to be cooled to below 50°C within 60 seconds. In the intermediate annealing step, the annealing temperature is 430-530℃, the annealing time is 6-9 hours, and an atmosphere protection is used during annealing; In the finishing rolling process, the final pass uses a small processing rate of 10% to 15% and a constant tension of 600 to 800 kg. In the heat treatment step of the finished product, the heat treatment temperature is 200-320℃, the heat treatment time is 2-6 hours, and an atmosphere protection is used during the heat treatment.

2. A method for preparing copper alloy plate and strip, characterized in that, Includes the following steps: Step 1: Prepare the alloy according to claim 1; Step 2: Melt the raw materials from Step 1, wherein Zn is added in the form of zinc ingots, Ce and Sr are added in the form of Cu-Ce and Cu-Sr master alloys, and Sn is added in the form of Sn blocks. Step 3: Casting is carried out at a melt temperature of 1160-1210℃, with a casting speed of 4-10 meters per hour. Borax is used as a flux to cover the melt in the crystallizer during casting. Step 4: Heat the sawn ingots to a temperature of 800-820℃; Step 5: Hot rolling of the ingot billet is carried out on the hot rolling equipment. The total processing rate of the hot rolled strip is 88% to 98%. The last pass of hot rolling is laminar flow cooling treatment, which requires the material to be cooled to below 50°C within 60 seconds. Step 6: Mill the surface of the hot-rolled strip. Step 7: Pre-finish rolling the milled strip. Step 8: Perform intermediate annealing on the pre-rolled strip in an annealing furnace at a temperature of 430-530°C for 6-9 hours, with atmosphere protection during annealing. Step 9: The pre-finished and annealed strip is finished by finishing rolling to the finished strip. The last rolling process uses a small processing rate of 10% to 15% and a constant tension of 600 to 800 kg. Step 10: Perform heat treatment on the finished strip and sheet material rolled in the previous step. The heat treatment temperature is 200-320℃ and the heat treatment time is 2-6 hours. An atmosphere protection is used during the heat treatment. Step 11: Clean and passivate the heat-treated finished strip to obtain the prepared copper alloy strip.

3. The method for preparing copper alloy plate and strip according to claim 2, characterized in that, In steps eight and ten, a 75% high-hydrogen atmosphere is used for protection.

4. The method for preparing copper alloy plate and strip according to claim 2, characterized in that, The passivation solution used in step eleven is a 1-3‰ benzotriazole solution prepared with deionized water.

5. The method for preparing copper alloy plate and strip according to claim 4, characterized in that, The passivation temperature in step eleven is 60–85°C.

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