CN113005326A

CN113005326A - Copper alloy strip and preparation method thereof

Info

Publication number: CN113005326A
Application number: CN202110214848.4A
Authority: CN
Inventors: 曾力维; 何科科; 种腾飞
Original assignee: Ningbo Jintian Copper Group Co Ltd
Current assignee: Ningbo Jintian Copper Group Co Ltd
Priority date: 2021-02-25
Filing date: 2021-02-25
Publication date: 2021-06-22
Anticipated expiration: 2041-02-25
Also published as: CN113005326B

Abstract

The invention discloses a copper alloy strip which is characterized by comprising the following components in percentage by mass: 7-11 wt%, P: 0.006-0.012 wt%, Sn: 0.5-1.5 wt%, Ni: 4 to 6 wt%, and the balance of copper and inevitable impurities. According to the invention, by controlling the addition content of elements such as Fe, Sn, Ni and P, the Fe-rich phase exists in the copper matrix in the form of a framework, the performances of improving strength and bending are achieved, and the matrix is purified to improve conductivity, the tensile strength of the copper alloy strip is 700-850 MPa, the conductivity is more than or equal to 25% IACS, the elongation is more than 10%, the 90-degree bending R/t is less than or equal to 0.5 of GW, the BW is less than or equal to 1.5, the temperature is kept at 500 ℃ for 5min, and the hardness value is 80% of the original hardness.

Description

Copper alloy strip and preparation method thereof

Technical Field

The invention belongs to the field of copper alloy, and particularly relates to a copper alloy strip and a preparation method thereof.

Background

The LED support is a bottom base of the LED lamp bead before packaging, the chip is fixed on the LED support, the positive electrode and the negative electrode are welded, and packaging glue is used for packaging and forming at one time. The existing LED support is generally made of tin-phosphor bronze, such as C5111, C5191 and the like, the conductivity of the tin-phosphor bronze is generally below 20% IACS, and when the tensile strength is more than or equal to 600MPa (H state or EH state), the bending performance is poor, the 90-degree bending R/t is difficult to meet the condition that GW is less than or equal to 0.5, BW is less than or equal to 1.5, wherein GW is bent along the vertical rolling direction, BW is bent along the parallel rolling direction, and when the shape of the LED support is more complex, the condition that the deformation processing generates cracks and the use requirement is difficult to meet exists; the existing LED bracket is generally used after being plated with tin, but the existing copper alloy for the LED bracket has the problems of difficult tin plating and easy stripping of the tin plating; for certain specific application fields, the high-temperature performance of the copper alloy has certain requirements, and the existing tin-phosphor bronze has poor high-temperature resistance and cannot meet the use requirements.

The invention patent CN201610634673.1 discloses a copper strip production process for an LED bracket, which comprises the following steps: (1) taking A-grade cathode copper as a raw material, continuously casting the A-grade cathode copper in a smelting device, covering charcoal and graphite flakes in the smelting device, and cooling by using cooling circulating water after casting is finished to prepare an up-drawing copper rod; (2) continuously extruding the prepared up-drawing copper rod in a continuous extruder; (3) performing multi-pass rolling by using a cold rolling unit according to the thickness of the copper strip for the LED bracket; (4) after rolling, performing bright annealing, and then grinding and polishing the surface of the copper strip; (5) slitting the rolled copper strip by using a slitting machine group to obtain a copper strip for the LED bracket; the copper strip produced by the copper strip production process of the LED bracket comprises 99.97-99.99% of copper and 6-9 ppm of oxygen in chemical components; the Vickers hardness HV of the copper strip is 106-112, the tensile strength is 300-340MPa, the elongation is 5-7%, and the surface roughness Ra is less than 0.05 mm; edge burr is less than 0.02mm, and conductivity is greater than 100.5% IACS. The LED bracket adopts high-content copper, has poor strength and high temperature resistance although the conductivity is high, and can only be applied to occasions with low requirements on strength or high temperature resistance.

Disclosure of Invention

The first technical problem to be solved by the invention is to provide a copper alloy strip with high strength, high conductivity, excellent bending and high temperature resistance.

The technical scheme adopted by the invention for solving the first technical problem is as follows: a copper alloy strip is characterized in that the copper alloy strip consists of the following components in percentage by mass: 7-11 wt%, P: 0.006-0.012 wt%, Sn: 0.5-1.5 wt%, Ni: 4 to 6 wt%, and the balance of copper and inevitable impurities.

Fe can improve the strength of a matrix, most of Fe in the invention takes Fe as the matrix, a small amount of Cu is dissolved in the Fe-rich phase (precipitated phase) of Fe, the Fe-rich phase exists in the copper matrix in the form of a framework and plays a role in improving the strength, the small amount of Fe is dissolved in Cu to form the matrix phase of Cu solid solution, the small amount of Fe and P are dissolved in the matrix phase to form supersaturated solid solution through solution and quenching treatment, then FeP intermetallic compounds are precipitated through aging treatment, the precipitated FeP intermetallic compounds play a role in dispersion strengthening, the FeP intermetallic compounds further improve the strength and hardness of the matrix and play an important role in improving the high temperature softening resistance of the alloy, when the content of Fe is lower than 7 wt%, the formed Fe-rich phase is insufficient, the structure is difficult to form the framework of the Fe-rich phase, so that the strength is insufficient, but when the Fe exceeds 11 wt%, the iron-rich phase can form an iron-rich phase with the size larger than 5 mu m in the casting process, so that the shaping of the material is poor, the processing is not facilitated, and meanwhile, the bending property of the material is poor.

Sn acts, Sn and Ni generate spinodal decomposition from the solid solution state of the matrix in the aging stage, and the spinodal decomposition is formed with Cu and Ni (Cu, Ni)₃The Sn particles play a role in amplitude modulation decomposition and strengthening, and further improve the strength, elasticity and high-temperature softening resistance of the alloy. If the Sn content is low, the spinodal decomposition strengthening effect is not strong, and if the Sn content is too high, the influence on the conductivity of the alloy is large, so that the Sn content is controlled to be 0.5-1.5 wt%.

Ni can be infinitely dissolved in the copper alloy and is an alloy element with negative zinc equivalent in the copper alloy, the corrosion resistance of the copper alloy can be effectively improved, the strengthening effect is achieved, and the Ni and the Cu and Sn form (Cu and Ni)₃The Sn particles play a role in amplitude modulation decomposition and strengthening, and further improve the strength, elasticity and high-temperature softening resistance of the alloy. When the Ni content is too low, the corrosion resistance of the alloy is poor and the spinodal decomposition strengthening at the aging stage is also weak. When the Ni content is too high, the conductivity of the alloy is influenced, so that the Ni addition amount is controlled to be 4-6 wt%.

Preferably, the alloy further comprises Mg: 0.008 to 0.015 wt%.

Preferably, the microstructure of the copper alloy strip contains an Fe-rich phase precipitated in a capillary fiber shape, and the length of the capillary fiber-shaped Fe-rich phase is less than or equal to 200nm, and the width of the capillary fiber-shaped Fe-rich phase is 1/20-1/10 of the length.

The Fe-rich phase is precipitated in a capillary fiber shape, compared with the traditional granular Fe-rich phase, a large amount of Fe-rich capillary fiber shapes are dispersed in a copper matrix and are overlapped and staggered with each other to form a strong framework of the material, so that the strength and the bending performance of the material are improved, meanwhile, the Fe-rich phase is precipitated from the copper matrix, the copper matrix is purified, the conductivity of the alloy is improved, the length of the capillary fiber-shaped Fe-rich phase is less than or equal to 200nm, the width of the capillary fiber-shaped Fe-rich phase is 1/20-1/10, the capillary fiber-shaped Fe-rich phase is in a short and thin state, the uniform dispersion of the Fe-rich phase is facilitated, the mechanical property stability of the material is improved, when the length of the Fe-rich phase is more than 200nm, the Fe-rich phase is easily interwoven together and is easily agglomerated, the local plasticity of the material is poor, when the width exceeds 1/20-1/10, the capillary fiber shapes cannot be formed or the capillary fibers are, is disadvantageous for mechanical properties, in particular bending properties.

Preferably, the capillary fibrous Fe-rich phase accounts for more than 80% of the total Fe-rich phase area content, and the number of the capillary fibrous Fe-rich phases is 50-400 in a region of 10 μm × 10 μm.

In order to improve the mechanical property stability of the material, the number of the capillary fibrous Fe-rich phases in a 10-micron area is 50-400, and in the range, the Fe-rich phases can realize the uniform dispersion effect, thereby being beneficial to the improvement of the bending property.

The LED support is plated with tin when in use, and the copper alloy strip is preferably used after subsequent tin plating, wherein the grain size of the copper alloy strip is less than or equal to 3 mu m, and the roughness of the copper alloy strip is 0.025-0.045 mu m.

Preferably, the tensile strength of the copper alloy strip is 700-850 MPa, the electric conductivity is more than or equal to 25% IACS, the 90-degree bending R/t is less than or equal to 0.5 at GW and less than or equal to 1.5 at BW, the heat preservation is carried out for 5min at 500 ℃, and the hardness value is 80% of the original hardness.

The second technical problem to be solved by the invention is to provide a preparation method of the copper alloy strip.

The technical scheme adopted by the invention for solving the second technical problem is as follows: a preparation method of a copper alloy strip is characterized by comprising the following steps: the processing process flow of the copper alloy strip is as follows:

smelting → semicontinuous casting → hot rolling → online solid solution → milling face → rough rolling → aging annealing → cleaning → finish rolling → finished product stress relief annealing → straightening; heating the cast ingot at the temperature of 1000-1050 ℃, keeping the temperature for 1-5 h, wherein the hot rolling starting temperature is 950-1000 ℃, the finishing rolling temperature is not less than 700 ℃, the rolling reduction rate of hot rolling is not less than 80%, and online spray cooling is carried out after finishing rolling to realize online solid solution.

The heating temperature of the cast ingot is 1000-1050 ℃. When the temperature is heated to the temperature, alloying elements such as Fe, Sn, Ni and the like can be dissolved in the matrix to the maximum extent, so that the precipitation strengthening of Fe and the spinodal decomposition strengthening of Ni and Sn are strong in the later aging process, and the performance of the material is optimized. However, when the heating temperature is too high, the ingot is easy to over-burn, and the hot rolling generates cracking and peeling defects.

The starting temperature of hot rolling is 950-1000 ℃, the hot processing and shaping of the copper alloy are better at the temperature, and the phenomena of hot rolling cracking and the like are not easy to generate. Meanwhile, at the temperature, the alloy has good processing and solid solution effects, Fe can be effectively and maximally dissolved in a copper alloy matrix, and simultaneously, the optimization of solid solution and aging performance can be realized by combining the hot rolling finishing temperature of more than or equal to 700 ℃ and the subsequent aging process, so that the coupling control of the strength and the conductivity of the copper alloy is realized. The iron-rich phase is subjected to fibrous deformation under the condition of high temperature and high processing rate by combining hot rolling with the reduction rate of more than or equal to 80 percent, and is converted into fibrous tissue from the granular state of the cast ingot, so that matrix tissue is provided for forming the capillary fibrous tissue in the later processing. The iron-rich fiber at this time has a large diameter, and the fibrous iron-rich phase is further fibrillated in the subsequent plastic cold working process, and the iron-rich phase becomes capillary fiber.

Preferably, the semi-continuous casting process comprises the following steps: the temperature of the copper liquid is controlled to be 1400-1450 ℃, the water pressure is controlled to be 100-150 KPa during semi-continuous casting, the casting speed is 40-50 mm/min, the frequency of a vibrator is 50-70 times/min, and the amplitude is 3-6 mm.

Preferably, the reduction rate of the rough rolling is not less than 80%, and the reduction rate of the finish rolling is not less than 30%.

Preferably, the temperature of the aging annealing is 320-360 ℃, and the heat is preserved for 10-15 h; the stress relief annealing temperature of the finished product is 400-450 ℃. In the aging annealing process, solid solution state Fe in the matrix is precipitated, and the Ni and Sn are subjected to spinodal decomposition to form (Cu, Ni)₃Sn, which further improves the strength, elasticity and high-temperature softening resistance of the alloy and greatly improves the conductivity of the alloy. After rolling the finished product, because of the deformation nonuniformity of the processed fiber structure, the processing residual stress exists in the structure, and in order to eliminate the residual stress of the finished product, low-temperature annealing in an air cushion furnace is carried out. The annealing temperature is lower than the high-temperature softening temperature of the alloy, but higher than the grain recovery temperature of the alloy, so that the annealing temperature of the destressing air cushion furnace is set to be 400-450 ℃.

Preferably, the cleaning process is degreasing → acid cleaning → passivation → drying; the degreasing agent is an aqueous solution with the pH value of 10-13, and the temperature of the aqueous solution is 70-80 ℃; the pickling adopts 100-130 g/L sulfuric acid, the temperature is less than or equal to 40 ℃, and Cu in acid liquor is adopted²⁺Less than or equal to 1.2 g/L; the passivation adopts a passivating agent with the solution concentration of 0.07-0.12%; and (4) drying after cleaning, wherein the drying temperature is 80-100 ℃.

Compared with the prior art, the invention has the advantages that:

by controlling the addition content of elements such as Fe, Sn, Ni and P, the Fe-rich phase exists in the copper matrix in a framework form, the strength and bending performance are improved, the matrix is purified, and the conductivity is improved, the tensile strength of the copper alloy strip is 700-850 MPa, the conductivity is more than or equal to 25% IACS, the elongation is more than 10%, the 90-degree bending R/t is less than or equal to 0.5 at GW, less than or equal to 1.5 at BW, the heat preservation is carried out for 5min at 500 ℃, and the hardness value is 80% of the original hardness.

Drawings

FIG. 1 is a photograph showing the microstructure of a semi-continuously cast slab according to example 1 of the present invention;

FIG. 2 is a photograph of the microstructure of the finished product of example 1 of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

Examples 1 to 10 are compositions of the present invention, as shown in table 1, and the process flow is:

1) smelting: the components in the table 1 are mixed, Cu, Ni and Sn are added into a smelting furnace to be heated and melted, and after the copper liquid is melted, covering agent glass is added for covering. And then, raising the temperature to 1450-1550 ℃, and slowly adding pure iron sheets according to the alloy proportion. And after the pure iron sheets are completely melted in the copper liquid, heating the copper liquid to 1500-1550 ℃, and preserving the heat for 20-30 minutes. Then reducing the temperature to 1350-1400 ℃, adding phosphorus-copper alloy and copper-magnesium alloy in sequence according to the proportion, keeping the temperature for 30 minutes, controlling the temperature to 1350-1400 ℃, fishing out slag, and adding covering agent cryolite and carbonic acid (the weight ratio is 1:1) for covering.

2) Semi-continuous casting; the ingot specification was 220mm thick by 620mm wide.

3) Hot rolling + on-line solid solution: the thickness after hot rolling is 12-14 mm, and the band width is 655 +/-5 mm.

4) Milling a surface: the milling amount of the single surface is 0.6-0.8 mm, and the thickness after milling is 11.5 mm.

5) Rough rolling: the rolling thickness is 1.5 +/-0.015 mm.

6) Trimming: the unilateral shearing is 7-8 mm, and the band width after shearing is 640 +/-1 mm.

7) Aging annealing: heating the furnace temperature to 320-360 ℃ according to a heating rate of 50-70 ℃/H, preserving the temperature for 10-15H, and adopting H for an annealing furnace₂And (5) gas reduction protection.

8) Cleaning: the degreasing agent is a p3 reagent (JQ-1 type metal cleaning agent) water solution, the PH range is 10-13, and the solution temperature is 70-80 ℃. Acid washing, wherein the concentration of sulfuric acid is 100-130 g/l, the temperature is less than or equal to 40 ℃, and Cu is contained in acid liquor²⁺Less than or equal to 1.2g/l, adopting CC-2002/high-efficiency environment-friendly passivator for passivation, wherein the concentration of the solution is 0.07-0.12%, and cleaning and drying at the temperature of 80-100 ℃ in an oven.

9) Finish rolling: firstly, the thickness of the strip is rolled to 0.32 +/-0.005 mm, and then the special roller is replaced to carry out finished product polishing rolling, wherein the rolling thickness is 0.3 +/-0.005 mm. The special roller is ground by a 400-mesh grinding wheel, and the surface roughness of the roller is controlled to be 0.020-0.040 mu m.

10) And (4) performing stress relief annealing on the finished product by using an air cushion type annealing furnace.

11) And (6) stretch bending and straightening. The straightened version is controlled within 5I.

12) And (5) splitting and packaging the finished product.

The strip samples of 10 prepared example alloys and 1 prepared comparative example alloy were tested for mechanical properties, electrical conductivity, and high temperature oxidation resistance, respectively.

Tensile test at room temperature according to GB/T228.1-2010 Metal Material tensile test part 1: room temperature test method was performed on an electronic universal mechanical property tester using a tape head specimen having a width of 12.5mm and a drawing speed of 5 mm/min.

Conductivity testing according to GB/T3048.2-2007 test method for electric properties of wires and cables part 2: resistivity test of metal material, the tester is ZFD microcomputer bridge DC resistance tester, sample width is 20mm, length is 500 mm.

Testing high-temperature softening performance: the original hardness H0 of the copper alloy strip is tested, the sample is placed into a heat preservation furnace at 500 ℃, the hardness H1 of the sample is tested after heat preservation is carried out for 30min, and the high temperature resistance softening performance of the sample is qualified when H1/H0 is more than or equal to 80 percent.

The bending performance test is carried out on a bending tester according to the bending test method of GBT 232-.

As can be seen from FIG. 1, a large amount of fine iron-rich phases are distributed in the semi-continuous casting billet, and the fine iron-rich phases provide favorable conditions for the generation of fibrous iron-rich phases after the subsequent hot rolling and the online solid solution, so that the final excellent comprehensive properties are realized.

TABLE 1 Components of inventive and comparative examples

Table 2 key process control parameters for embodiments of the invention

TABLE 3 Key Process control parameters and microstructures for embodiments of the invention

TABLE 4 surface Properties of examples of the invention and mechanical Properties of examples and comparative examples

Claims

1. A copper alloy strip is characterized in that the copper alloy strip consists of the following components in percentage by mass: 7-11 wt%, P: 0.006-0.012 wt%, Sn: 0.5-1.5 wt%, Ni: 4 to 6 wt%, and the balance of copper and inevitable impurities.

2. The copper alloy strip according to claim 1, wherein: further comprises Mg: 0.008 to 0.015 wt%.

3. The copper alloy strip according to claim 1, wherein: the microstructure of the copper alloy strip contains a Fe-rich phase precipitated in a capillary fiber shape, the length of the capillary fiber-shaped Fe-rich phase is less than or equal to 200nm, and the width of the capillary fiber-shaped Fe-rich phase is 1/20-1/10 of the length.

4. The copper alloy strip according to claim 3, wherein: the capillary fibrous Fe-rich phase accounts for more than 80% of the total Fe-rich phase area content, and the number of the capillary fibrous Fe-rich phases is 50-400 in a 10-micron area.

5. The copper alloy strip according to claim 1, wherein: the grain size of the copper alloy strip is less than or equal to 3 mu m, and the roughness is 0.025-0.045 mu m.

6. The copper alloy strip according to claim 1, wherein: the tensile strength of the copper alloy strip is 700-850 MPa, the electric conductivity is more than or equal to 25% IACS, the 90-degree bending R/t is less than or equal to 0.5 at GW, less than or equal to 1.5 at BW, the heat preservation is carried out for 5min at 500 ℃, and the hardness value is 80% of the original hardness.

7. A method of producing the copper alloy strip of any one of claims 1 to 6, characterized in that: the processing process flow of the copper alloy strip is as follows:

8. The method of making a copper alloy strip according to claim 7, wherein: the semi-continuous casting process comprises the following steps: the temperature of the copper liquid is controlled to be 1400-1450 ℃, the water pressure is controlled to be 100-150 KPa during semi-continuous casting, the casting speed is 40-50 mm/min, the frequency of a vibrator is 50-70 times/min, and the amplitude is 3-6 mm.

9. The method of making a copper alloy strip according to claim 7, wherein: the reduction rate of the rough rolling is more than or equal to 80 percent, and the reduction rate of the finish rolling is more than or equal to 30 percent.

10. The method of making a copper alloy strip according to claim 7, wherein: the temperature of the aging annealing is 320-360 ℃, and the temperature is kept for 10-15 h; the stress relief annealing temperature of the finished product is 400-450 ℃.