High-strength copper alloy strip and production process thereof

Abstract

The invention discloses a high-strength copper alloy strip and a production process thereof. The copper alloy strip comprises 1%-2.2% of Sn, 0.03%-0.15% of P, 0.5%-1.0% of Ni, smaller than or equal to 0.5% of Zn, smaller than or equal to 0.3% of Fe and the balance Cu. The preparation method comprises the following steps of: preparing; batching, smelting, horizontal continuous casting, surface milling, rough rolling and cogging, homogenizing annealing, rough rolling, edge washing and shearing, second annealing, surface deoxidation pickling, first finish rolling or rolling by 20 rolling mills, third annealing, surface deoxidation pickling, second finish rolling or rolling by 20 rolling mills, fourth annealing, surface deoxidation pickling and second finish rolling. Third finish rolling, stretch bending and straightening, low-temperature stress annealing, stretch bending and straightening, surface pickling and passivating, finished product shearing, inspecting and warehousing. The product has the characteristics of high tensile strength, high yield strength, high elasticity, high conductivity, stress relaxation resistance, stress corrosion cracking resistance and the like, and is low in production cost and wide in application.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy strips, and particularly to a high-strength copper alloy strip and its production process. Background Art

[0002] In recent years, with the development of the electronics industry, connectors of electrical and electronic components tend to be miniaturized and thinned. The copper alloy used to manufacture connectors is required to have good strength and stamping formability, and at the same time, it is also required to have high electrical conductivity and anti-creep characteristics.

[0003] However, the current connector copper alloy can meet the requirements in terms of strength, but does not have good stress relaxation resistance and stress corrosion cracking resistance. Although tin phosphor bronze has high strength, good stress relaxation resistance and stress corrosion cracking resistance, its electrical conductivity is relatively low, only about 13% IACS, and a large amount of heat will be generated during the energization of the connector (only when the electrical conductivity reaches more than 30% IACS can the heat generated during energization be effectively suppressed). Therefore, it is necessary to develop a new alloy product with high strength, high elasticity, high electrical conductivity, stress relaxation resistance and corrosion cracking resistance. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a high-strength copper alloy strip and its production process. The product has characteristics such as high tensile strength, high yield strength, high elasticity, high electrical conductivity, stress relaxation resistance, and stress corrosion cracking resistance, low production cost, and wide application fields.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A high-strength copper alloy strip, calculated by mass percentage of the copper alloy strip, the copper alloy strip includes 1-2.2% of Sn, 0.03-0.15% of P, 0.5-1.0% of Ni, ≤0.5% of Zn, ≤0.3% of Fe, and the balance is Cu.

[0007] The thickness of the copper strip is 0.1-0.6 mm; the width is 10-400 mm.

[0008] The tensile strength of the copper alloy strip is 550-750 MPa, and the electrical conductivity ≥30% IACS.

[0009] A production process of a high-strength copper alloy strip, characterized in that it comprises the following steps: batching → melting → horizontal continuous casting → milling → rough rolling and blooming → homogenization annealing → rough rolling → washing and trimming → second annealing → surface deoxidation pickling → first finish rolling or rolling by a 20-high rolling mill → third annealing → surface deoxidation pickling → second finish rolling or rolling by a 20-high rolling mill → fourth annealing → surface deoxidation pickling → third finish rolling → stretch-bending leveling → low-temperature stress annealing → stretch-bending leveling → surface pickling and passivation → finished product shearing, inspection and warehousing.

[0010] The melting temperature is 1270 - 1290 °C.

[0011] Milling means milling 0.7 - 0.75 mm from each of the upper and lower surfaces.

[0012] The rough rolling and blooming after melting reduces the material from 14.5 mm to 8 mm; the rough rolling after homogenization annealing reduces the material from 8 mm to 1.5 mm.

[0013] The homogenization annealing temperature is 700 °C and the time is 11 h; the second annealing temperature is 540 °C and the time is 5 h; the third annealing temperature is 520 °C and the time is 5 h; the fourth annealing temperature is 510 °C and the time is 5 h; the low-temperature stress annealing temperature is 260 °C and the time is 4 h.

[0014] The first finish rolling or rolling by a 20-high rolling mill reduces the material to 0.5 mm; the second finish rolling or rolling by a 20-high rolling mill reduces the material to 0.195 mm.

[0015] The third finish rolling reduces the material to 0.102 - 0.112.

[0016] The beneficial effects of the present invention are as follows: the tensile strength of the product can reach above 550 MPa, the yield strength can reach above 700 MPa, and the conductivity reaches above 30% IACS, fully meeting the high tensile strength, high yield strength, high elasticity, high conductivity, stress relaxation resistance, stress corrosion cracking resistance and other characteristics required for materials used in electrical and electronic components. It has an obvious price advantage and can replace imported copper alloys (such as MF202, CAC5, NB109, etc.), and even can replace some low-strength C7025; the product has a broad market prospect and can be applied to fields such as lead frame materials, connectors, chip carriers, server terminals, heat dissipation components, electrical tools (motor brush components), energy storage electrical appliances, connecting pieces of rechargeable lithium batteries, high-performance household appliances, etc. Description of the Drawings

[0017] Figure 1 It is a structural diagram of the pickling device improved according to the present invention;

[0018] Figure 2 is Figure 1Cross-sectional view in the A-A direction;

[0019] Figure 3 is Figure 2 Enlarged view at position B in the figure.

[0020] In the figure: pickling tank 1, conveying roller 2, stirring roller 3, rotating shaft 31, flow stirring member 32, cylindrical part 321, conical part 322, turbine blade 323, spray hole 324, input roller 4, output roller 5. Specific implementation mode

[0021] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation modes:

[0022] By mass percentage of the copper alloy strip, the high-strength copper alloy strip of the present invention includes 1-2.2% of Sn, 0.03-0.15% of P, 0.5-1.0% of Ni, ≤0.5% of Zn, ≤0.3% of Fe, and the balance is Cu. The thickness of the copper strip is 0.1-0.6 mm; the width is 10-400 mm.

[0023] The production process steps of the high-strength copper alloy strip are: batching → melting → horizontal continuous casting → milling → rough rolling and blooming → homogenization annealing → rough rolling → washing and trimming → second annealing → surface deoxidation pickling → first finish rolling or rolling on a 20-high rolling mill → third annealing → surface deoxidation pickling → second finish rolling or rolling on a 20-high rolling mill → fourth annealing → surface deoxidation pickling → third finish rolling → stretch-bend straightening → low-temperature stress annealing → stretch-bend straightening → surface pickling and passivation → finished product shearing, inspection and warehousing. Among them, the melting temperature is 1270-1290 °C; milling is to mill 0.7-0.75 mm from both the upper and lower surfaces; the rough rolling and blooming after melting is to roll the material from 14.5 mm to 8 mm; the homogenization annealing temperature is 700 °C and the time is 11 h; the rough rolling after homogenization annealing is to roll the material from 8 mm to 1.5 mm; the second annealing temperature is 540 °C and the time is 5 h; the first finish rolling or rolling on a 20-high rolling mill is to roll the material to 0.5 mm; the third annealing temperature is 520 °C and the time is 5 h; the second finish rolling or rolling on a 20-high rolling mill is to roll the material to 0.195 mm; the fourth annealing temperature is 510 °C and the time is 5 h; the third finish rolling is to roll the material to 0.102-0.112; the low-temperature stress annealing temperature is 260 °C and the time is 4 h. The above specific process parameters are actually adjusted according to the required thickness, width and composition of the produced copper strip.

[0024] Specific embodiments are as follows:

[0025] Embodiment 1

[0026] Production process of high-strength copper alloy strip, comprising the following steps: batching (preparing raw materials and batching according to the required chemical composition of the alloy) → melting (melting temperature is 1285°C) → horizontal continuous casting (casting process: pulling 15 mm, reverse pushing -1 mm, stopping for 3.3 seconds, reverse pushing two 1.8 mm. The casting control temperature of the holding furnace is 1200 ± 10°C, and the billet thickness is 16 mm. The liquid level of the holding furnace is covered with calcined and dried charcoal, and the covering thickness is not less than 5 cm. The temperature difference at the end face of the billet is controlled below 50°C. The electromagnetic stirring process is adopted, with a frequency of 20 HZ, a current of 20 A, stirring for 4 seconds and stopping for 15 seconds) → facing (facing is carried out on both the upper and lower surfaces, and the material thickness after facing is 14.5 mm) → rough rolling and blooming (rough rolling the material from 14.5 mm to 8 mm) → homogenization annealing (annealing temperature is 700°C, annealing time is 11 h) → rough rolling (rolling from 8 mm to 1.5 mm) → washing and trimming the edges (no cracked edges, no burrs) → second annealing (annealing temperature is 540°C, annealing time is 5 h) → surface deoxidization and pickling → first finish rolling or rolling on a 20-high rolling mill (rolling to 0.5 mm, anti-sticking and recoiling before annealing) → third annealing (annealing temperature is 520°C, annealing time is 5 h) → surface deoxidization and pickling → second finish rolling or rolling on a 20-high rolling mill (finish rolling to 0.195 mm, recoiling after rolling) → fourth annealing (annealing temperature is 510°C, annealing time is 5 h) → surface deoxidization and pickling → third finish rolling (rolling to 0.11 mm) → stretch-bending straightening → low-temperature stress annealing (annealing temperature is 260°C, annealing time is 4 h) → stretch-bending straightening → surface pickling and passivation → finished product splitting, inspection and warehousing.

[0027] Example 2

[0028] Production process of high-strength copper alloy strip, including the following steps: batching (preparing raw materials and batching according to the required chemical composition of the alloy) → melting (melting temperature is 1270 °C) → horizontal continuous casting (casting process: pulling 15 mm, reverse pushing -1.6 mm and stopping for 3.8 seconds, reverse pushing two 2.2 mm. The casting temperature of the holding furnace is controlled at 1200 ± 10 °C, and the thickness of the billet is 16 mm. The liquid level of the holding furnace is covered with calcined and dried charcoal, and the covering thickness is not less than 5 cm. The temperature difference at the end face of the billet is controlled below 50 °C. The electromagnetic stirring process is adopted, with a frequency of 20 HZ, a current of 26 A, stirring for 4 seconds and stopping for 15 seconds) → milling (milling 0.7 mm from both the upper and lower surfaces, and the material is 14.5 mm after milling) → rough rolling and blooming (rolling from 14.5 mm to 8 mm) → homogenization annealing (annealing temperature is 700 °C, annealing time is 11 h) → rough rolling (rolling from 8 mm to 1.5 mm) → washing and trimming (no cracked edges, no burrs) → second annealing (annealing temperature is 540 °C, annealing time is 5 h) → surface deoxidation pickling → first finishing rolling or rolling on a 20-high rolling mill (rolling to 0.5 mm, anti-sticking and recoiling before annealing) → third annealing (annealing temperature is 520 °C, annealing time is 5 h) → surface deoxidation pickling → second finishing rolling or rolling on a 20-high rolling mill (finishing rolling to 0.195 mm, recoiling after rolling) → fourth annealing (annealing temperature is 510 °C, annealing time is 5 h) → surface deoxidation pickling → third finishing rolling (finishing rolling to 0.102 mm) → stretch-bending straightening → low-temperature stress annealing (annealing temperature is 260 °C, annealing time is 4 h) → stretch-bending straightening → surface pickling and passivation → finished product splitting, inspection and warehousing.

[0029] Example 3

[0030] Production process of high-strength copper alloy strip, including the following steps: batching (preparing raw materials and batching according to the chemical composition required for the alloy) → melting (melting temperature is 1290 °C) → horizontal continuous casting (casting process: pulling 15 mm, reverse pushing -1.6 mm and stopping for 3.5 seconds, reverse pushing two 2 mm. The pulling and casting control temperature of the holding furnace is 1200 ± 10 °C, and the thickness of the cast billet is 16 mm. The liquid level of the holding furnace is covered with calcined and dried charcoal, and the covering thickness is not less than 5 cm. The temperature difference at the end face of the cast billet is controlled below 50 °C. The electromagnetic stirring process is adopted, with a frequency of 20 HZ, a current of 24 A, stirring for 4 seconds and stopping for 15 seconds) → milling (0.7 mm is milled off from both the upper and lower surfaces, and the material is 14.5 mm after milling) → rough rolling and blooming (the material is rolled from 14.5 mm to 8 mm) → homogenization annealing (annealing temperature is 700 °C, annealing time is 11 h) → rough rolling (rolled from 8 mm to 1.5 mm) → washing and trimming the edges (no cracked edges, no burrs) → second annealing (annealing temperature is 540 °C, annealing time is 5 h) → surface deoxidization and pickling → first finish rolling or rolling on a 20-high rolling mill (rolled to 0.5 mm, anti-sticking and re-winding before annealing) → third annealing (annealing temperature is 520 °C, annealing time is 5 h) → surface deoxidization and pickling → second finish rolling or rolling on a 20-high rolling mill (rolled to 0.195 mm, re-winding after rolling) → fourth annealing (annealing temperature is 510 °C, annealing time is 5 h) → surface deoxidization and pickling → third finish rolling (rolled to 0.112 mm) → stretch-bend straightening → low-temperature stress annealing (annealing temperature is 260 °C, annealing time is 4 h) → stretch-bend straightening → surface pickling and passivation → finished product splitting, inspection and warehousing.

[0031] The properties of the copper alloy strips prepared in Examples 1-3 are shown in Table 1. For the evaluation of the stress corrosion cracking resistance of the copper alloy strip, a bending stress equivalent to 80% of the 0.2% yield strength is applied to the test piece cut from the copper alloy strip, and in this state, the test piece is held in a dryer containing 3 wt% ammonia water at a temperature of 25 °C. The test piece is taken out every 1 hour, and the time until cracking is observed through an optical microscope.

[0032] Table 1

[0033]

[0034] Example 4

[0035] In the pickling process of the copper alloy strip, the acid undergoes a series of chemical and physical reactions with the oxides on the strip surface, causing them to fall off and dissolve from the strip surface, thereby obtaining a clean surface. The pickling chemical reaction rate is affected by the diffusion rates of the reactants and products, but the current pickling process is carried out by controlling the relative movement rate of the acid solution and the copper alloy strip, and the pickling rate and pickling effect are not ideal enough.

[0036] In this embodiment, the pickling device is improved. As Figures 1 to 3 shown, the improved pickling device includes a pickling tank 1, a set of conveying rollers 2 rotatably penetrating through the pickling tank 1, and a set of stirring rollers 3 rotatably penetrating through the pickling tank 1. The set of conveying rollers 2 includes three arranged in an isosceles triangle distribution. The copper alloy strip passes through the three conveying rollers 2 in a wavy shape, that is, the copper alloy strip successively passes through the lower end of a conveying roller 2 located below, the upper end of the conveying roller 2 located above, and the lower end of another conveying roller 2 located below. The set of stirring rollers 3 includes a pair. One of the stirring rollers 3 is arranged above a conveying roller 2 located below, and the other stirring roller 3 is arranged below the conveying roller 2 located above. The stirring roller 3 includes a rotating shaft 31 and a row of flow stirring members 32 fixedly sleeved on the rotating shaft 31 at intervals. The flow stirring member 32 includes a cylindrical barrel portion 321 and a conical barrel portion 322 connected front and back. The conical barrel portion 322 is arranged with the front larger and the back smaller. A turbine blade 323 is arranged inside the cylindrical barrel portion 321, and a plurality of spray holes 324 are distributed on the outer surface of the conical barrel portion 322.

[0037] The improved pickling device further includes an input roller 4 outside one side of the pickling tank 1 and multiple pairs of output rollers 5 outside the other side of the pickling tank 1. The copper alloy strip passes from the upper end surface of the input roller 4 into the pickling tank 1 and is output from the pickling tank 1 by passing between each pair of output rollers 5. A pair of output rollers 5 has a straightening effect on the copper alloy strip.

[0038] Taking Figure 2 as the reference direction, when the two stirring rollers 3 rotate clockwise to stir the acid solution, the acid solution flows to wash the strip. At the same time, the flow stirring members 32 rotate with the stirring rollers 3. Due to the action of the turbine blade 323, the acid solution is sucked into the flow stirring members 32 and diffused and sprayed out through the spray holes 324 on the conical barrel portion 322, so that the acid solution generates more directional flow. And in the stage where the strip passes through the input roller 4 and the first lower conveying roller 2, the acid solution sprayed by the flow stirring members 32 on the first stirring roller 3 washes its upper surface from bottom to top. In the stage where the strip passes through the first lower conveying roller 2 and the upper conveying roller 2, the acid solution sprayed by the flow stirring members 32 on the first stirring roller 3 washes its upper surface from top to bottom. In the stage where the strip passes through the first lower conveying roller 2 and the upper conveying roller 2, the acid solution sprayed by the flow stirring members 32 on the second stirring roller 3 washes its lower surface from bottom to top. In the stage where the strip passes through the upper conveying roller 2 and the second lower conveying roller 2, the acid solution sprayed by the flow stirring members 32 on the second stirring roller 3 washes its upper and lower surfaces from top to bottom, improving the pickling effect and pickling rate and improving the performance of the strip.

[0039] Using the pickling device improved in this embodiment and producing copper alloy according to the method of Embodiment 1, it is found that the pickling efficiency is increased by 6.3%, the tensile strength is only reduced by 1.06%, and the yield strength is only reduced by 0.97%, meeting the requirements. The stress relaxation resistance rate at 100 °C for 1000 h is increased to 91.6%. Stress corrosion cracking of the strip is observed at 92 h.

[0040] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-strength copper alloy strip, characterized in that: By mass percentage of the copper alloy strip, the copper alloy strip comprises 1-2.2% of Sn, 0.03-0.15% of P, 0.5-1.0% of Ni, ≤0.5% of Zn, ≤0.3% of Fe, and the balance is Cu.

2. The high-strength copper alloy strip according to claim 1, wherein: The thickness of the copper strip is 0.1-0.6 mm; the width is 10-400 mm.

3. The high-strength copper alloy strip according to claim 1, wherein: The tensile strength of the copper alloy strip is 550-750 MPa, and the conductivity is ≥30% IACS.

4. A production process of the high-strength copper alloy strip according to any one of claims 1-3, characterized in that: It includes the following steps: batching → melting → horizontal continuous casting → facing → rough rolling and blooming → homogenization annealing → rough rolling → washing and trimming → second annealing → surface deoxidation pickling → first finish rolling or 20-high mill rolling → third annealing → surface deoxidation pickling → second finish rolling or 20-high mill rolling → fourth annealing → surface deoxidation pickling → third finish rolling → stretch-bending straightening → low-temperature stress annealing → stretch-bending straightening → surface pickling and passivation → finished product shearing, inspection and warehousing.

5. The production process of a high-strength copper alloy strip according to claim 4, characterized in that: The melting temperature is 1270-1290 °C.

6. The production process of a high-strength copper alloy strip according to claim 4, characterized in that: Facing is to mill off 0.7-0.75 mm from both the upper and lower surfaces.

7. The production process of a high-strength copper alloy strip according to claim 4, characterized in that: The rough rolling and blooming after melting is to roll the material from 14.5 mm to 8 mm; the rough rolling after homogenization annealing is to roll the material from 8 mm to 1.5 mm.

8. The production process of a high-strength copper alloy strip according to claim 4, characterized in that: The homogenization annealing temperature is 700 °C and the time is 11 h; the second annealing temperature is 540 °C and the time is 5 h; the third annealing temperature is 520 °C and the time is 5 h; the fourth annealing temperature is 510 °C and the time is 5 h; The low-temperature stress annealing temperature is 260 °C and the time is 4 h.

9. The production process of a high-strength copper alloy strip according to claim 4, characterized in that: The first finish rolling or 20-high mill rolling is to roll the material to 0.5 mm; the second finish rolling or 20-high mill rolling is to roll the material to 0.195 mm.

10. The production process of a high-strength copper alloy strip according to claim 4, characterized in that: The third finish rolling is to roll the material to 0.102-0.112.

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