A method for producing a low-tin low-nickel low-phosphorus copper alloy strip

Abstract

This application discloses a method for preparing low-tin, low-nickel, and low-phosphorus copper alloy strip, comprising the following steps: (1) batching; (2) smelting and horizontal continuous casting; (3) milling; (4) rough rolling; (5) trimming and rewinding; (6) bell furnace annealing; (7) cleaning; (8) bottom rolling; (9) air cushion furnace annealing; (10) finished product rolling; (11) finished product cleaning; (12) finished product tension bending and straightening; (13) finished product slitting; (14) packaging and shipping. This invention controls the tin, nickel, and phosphorus content in the copper alloy to a low level, and by adjusting the rolling pressure and speed during rough rolling, the rolling speed during bottom rolling, the cleaning parameters during finished product cleaning, and the tension bending and straightening parameters during finished product tension bending and straightening, a copper alloy material with good hardness, tensile strength, and conductivity is prepared that is suitable for use in industries such as switch materials, contactors, connectors, and electromechanical equipment.

Description

Technical Field

[0001] This invention belongs to the field of copper alloy strip processing technology, and particularly relates to a method for preparing low-tin, low-nickel, and low-phosphorus copper alloy strip. Background Technology

[0002] Copper, as a good conductor of electricity and heat, is widely used in relay-related industries. Tin-phosphorus bronze, a ternary alloy formed by adding tin to copper and using phosphorus as a deoxidizer, possesses high strength, excellent elasticity, corrosion resistance, antimagnetism, easy brazing, electroplating, and good processing properties. It is currently the most widely used elastic copper alloy material, used in electronic, communication, and electrical equipment to manufacture various connectors, relays, contactors, terminals, contacts, diaphragms, and springs.

[0003] Due to the scarcity of tin resources, low-tin copper alloys have begun to be used. The traditional preparation process of high-tin phosphorus copper alloys cannot meet the production requirements of low-tin phosphorus copper alloy strips. It is necessary to develop a copper alloy material preparation process that is suitable for low-tin phosphorus copper alloy strips and can be used in industries such as switch materials, contactors, connectors and relays.

[0004] However, due to its lower tin content, the strength and hardness of low-tin phosphorus copper alloy strips are significantly reduced compared to high-tin phosphorus copper alloys. How to improve the strength and hardness of low-tin phosphorus copper alloy strips through copper alloy strengthening is another problem that needs to be solved.

[0005] Shot peening is a widely used surface strengthening process. It involves bombarding the workpiece surface with shot, implanting residual compressive stress, and causing intense plastic deformation. Through microscopic mechanisms such as dislocation movement, this leads to grain refinement, significantly improving the material's surface properties, overall performance, and lifespan. Compared to fine-grained materials produced by traditional deposition and coating techniques, shot peening offers advantages such as lower cost, simpler process, no pollution, identical chemical composition to the matrix, gradual and smooth performance gradients, and less susceptibility to peeling during use. However, the strengthening effect of shot peening varies depending on the workpiece's processing steps. Choosing the appropriate time for shot peening is crucial for effectively improving workpiece performance.

[0006] In summary, how to provide a method for preparing low-tin, low-nickel, and low-phosphorus copper alloy strip that can meet the requirements of industries such as switch materials, contactors, connectors, and relays while reducing the content of tin, nickel, and phosphorus, and also has high strength and hardness, is an urgent problem to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing low-tin, low-nickel, and low-phosphorus copper alloy strip. By adjusting the rolling pressure and speed during rough rolling, the rolling speed during bottom-rolling, the cleaning parameters during finished product cleaning, and the tension-bending parameters during finished product straightening, a copper alloy material with good hardness, tensile strength, and conductivity is prepared, which is suitable for use in industries such as switch materials, contactors, connectors, and relays. Furthermore, this invention introduces shot peening treatment with copper alloy strengthening properties into specific processing steps of the copper alloy strip, which can significantly overcome the strength and hardness defects present in low-tin, low-nickel, and low-phosphorus copper alloy strip.

[0008] The first objective of this invention is to provide a copper alloy strip with a conductivity ≥40% IACS, hardness ≥120HV, tensile strength ≥390MPa, and elongation ≥10% for industries such as switch materials, contactors, connectors, and relays. To achieve this objective, this invention adjusts the rolling pressure and speed during rough rolling, the rolling speed during bottom-feed rolling, the cleaning parameters during finished product cleaning, and the tension-bending straightening parameters for finished product.

[0009] The technical solution of the present invention is as follows:

[0010] The low-tin, low-nickel, and low-phosphorus copper alloy strip to be prepared by the present invention comprises, by mass percentage: 1-4% tin, 0.01-0.06% nickel, 0.01-0.05% phosphorus, with the balance being copper and unavoidable impurities, wherein the unavoidable impurities (especially Pb) are ≤0.05%.

[0011] A method for preparing a low-tin, low-nickel, and low-phosphorus copper alloy strip includes the following steps: (1) batching; (2) smelting and horizontal continuous casting; (3) milling; (4) rough rolling; (5) trimming and rewinding; (6) bell furnace annealing; (7) cleaning; (8) bottom rolling; (9) air cushion furnace annealing; (10) finished product rolling; (11) finished product cleaning; (12) finished product tension bending and straightening; (13) finished product slitting; and (14) packaging and shipping.

[0012] Step (4) The rolling speed of the rough rolling is 50-150m / min and the rolling pressure is 4500-5800KN.

[0013] The rolling speed for step (8) of the bottom rolling is 100-150 m / min.

[0014] Step (11) The cleaning medium used for cleaning the finished product is sulfuric acid with a mass percentage of 4.5-6.5%, and the passivation solution used is passivation solution HC-09 with a mass percentage of 0.1-0.2%.

[0015] Step (12) The tension before and after the finished product bending straightening is 16-20 N / mm. 2The speed is 100-200 m / min. Preferably, the speed of the finished product bending straightening is 120-180 m / min.

[0016] Preferably, step (1) specifically involves using nickel blocks, tin ingots, electrolytic copper, and phosphorus copper alloy as raw materials, and mixing them according to the alloy composition ratio.

[0017] Preferably, step (2) specifically involves: adding the prepared material from step (1) into a melting furnace for melting, with a melting temperature of 1100-1200℃ and a traction speed of 10-16mm / s. After the composition is found to be qualified by a spectrometer, the material is transferred to a holding furnace for horizontal continuous casting to produce a billet.

[0018] Preferably, step (3) specifically involves milling the cast billet produced in step (2) using a milling machine at a milling speed of 2-5 m / min.

[0019] Preferably, step (4) specifically involves: performing multiple rough rolling passes on the strip obtained in step (3), with a rolling speed of 50-150 m / min, a rolling pressure of 4500-5800 KN, a total processing rate of 85-92%, and 7-9 rolling passes. After rolling to the target thickness, the strip is rolled into a coil.

[0020] Preferably, step (5) specifically involves: trimming the strip obtained in step (4) at a speed of 20-45 m / min and rewinding tension of 2500-3000 N.

[0021] Preferably, step (6) specifically involves: annealing the strip obtained in step (5) with full hydrogen in a bell furnace at a temperature of 400-500℃ for 6-8 hours, with a furnace exit temperature of ≤65℃, and vacuuming and filling with protective gas before exiting the furnace.

[0022] Preferably, step (7) specifically involves: performing conventional cleaning on the strip obtained in step (6) at a cleaning speed of 20-45 m / min.

[0023] Preferably, step (8) specifically involves: rolling the strip obtained in step (7) with a rolling speed of 100-150 m / min, a rolling pressure of 1500-2500 KN, a total processing rate of 60-85%, and 4-6 rolling passes.

[0024] Preferably, step (9) specifically involves annealing the strip obtained in step (8) in an air cushion furnace at a temperature of 500-700℃ and an annealing rate of 20-50 m / min.

[0025] Preferably, step (10) specifically involves rolling the strip obtained in step (9) into finished product at a rolling speed of 120-180 m / min and a total processing rate of 20-30%.

[0026] Preferably, step (11) specifically involves cleaning the strip obtained in step (10), using dilute sulfuric acid with a concentration of 4.5-6.5% as the cleaning medium, HC-09 passivation solution with a concentration of 0.1-0.2%, a passivation solution temperature of 70-90℃, and a cleaning speed of 20-80m / min.

[0027] The passivation solution HC-09 was purchased from Hangzhou Baimu Surface Technology Co., Ltd., and diluted to the required concentration before use.

[0028] Preferably, step (12) specifically involves: performing tension bending straightening on the strip obtained in step (11), with the tension before and after bending straightening being 16-20 N / mm. 2 The speed is 100-200m / min.

[0029] The second objective of this invention is to overcome the strength and hardness defects caused by the low tin content in copper alloy strips. To achieve this objective, this invention introduces shot peening, which has a copper alloy strengthening effect, into specific processing steps of copper alloy strips.

[0030] The technical solution of the present invention is as follows: before the second and third rolling passes of the bottom rolling in step (8), shot peening is also included. The diameter of the shot is 0.3-1mm, the shot peening pressure is 0.4-0.8MPa, and the shot peening time is 8-20min.

[0031] Preferably, the projectile is a metal projectile or a ceramic projectile.

[0032] Preferably, the processing rate of the second rolling pass is 25-30%, the diameter of the shot during shot peening is 0.6-1mm, the shot peening pressure is 0.65-0.8MPa, and the shot peening time is 8-14min.

[0033] Preferably, the processing rate of the third rolling pass is 15-28%, the diameter of the shot during shot peening is 0.3-0.5 mm, the shot peening pressure is 0.4-0.5 MPa, and the shot peening time is 15-20 min.

[0034] The present invention also provides a low-tin, low-nickel, and low-phosphorus copper alloy strip prepared according to the above-described preparation method.

[0035] The copper alloy strip has a conductivity ≥40% IACS, a hardness ≥120HV, a tensile strength ≥390MPa, and an elongation ≥10%.

[0036] The beneficial effects of this invention are as follows:

[0037] 1. This invention provides a method for producing low-tin, low-nickel, and low-phosphorus copper alloy strips and sheets. By appropriately reducing the tin content in the copper alloy strip and controlling the content of nickel and phosphorus elements, the Sn content is reduced, thus minimizing component segregation. At the same time, the presence of an appropriate amount of Sn can improve the tensile strength and hardness of the copper alloy. The appropriate addition of phosphorus can improve the fluidity of the melt and enhance the weldability of the alloy. Ni and Cu can be infinitely miscible to form a continuous solid solution, which can improve the hardness of the copper alloy without significantly affecting its conductivity. Furthermore, the addition of Ni can improve the cold pressure processing performance of the copper alloy strips and sheets.

[0038] 2. In preparing low-tin, low-nickel, and low-phosphorus copper alloy strips, this invention adjusts the rolling force and speed during rough rolling, the rolling speed during bottom rolling, the cleaning parameters during finished product cleaning, and the tension and bending straightening parameters during finished product straightening, thus producing copper alloy materials that are well-suited for use in industries such as switch materials, contactors, connectors, and electromechanical equipment.

[0039] Specifically:

[0040] The optimized step (4) roughing process of this invention uses a larger rolling pressure (the conventional rolling pressure is about 3000KN) and a lower rolling speed compared to the conventional process, in order to ensure the stability of the strip during the rolling process and the more uniform size of the strip after rolling.

[0041] The optimized step (8) of this invention is a bottom-rolling process. Compared with other products of the same specifications, the rolling speed is slower (the conventional rolling speed is about 200m / min). When the product is rolled at 100-150m / min, the surface of the strip can be fully cooled during rolling, ensuring that the strip will not cause thermal scratches and mill resonance due to excessive temperature.

[0042] In the optimized step (11) of the present invention, the cleaning process of the finished product uses a dilute sulfuric acid with a concentration of 4.5-6.5% as the cleaning medium. This medium concentration can ensure that while removing impurities such as oxides, oxide films, and dirt from the surface of copper and its alloys, it can also ensure that the residual acid on the surface of the copper strip is reduced, so that the residual acid on the surface of the copper strip before passivation is cleaned. At the same time, the passivation solution concentration of 0.1-0.2% can ensure that a passivation film is formed on the surface of the copper strip after passivation without producing white ash.

[0043] The optimized step (12) of this invention, the finished product tension bending straightening process, has a tension of approximately 15 N / mm compared to conventional tension bending straightening. 2 The bending speed is approximately 220 m / min. This product uses a larger bending tension and a lower bending speed. With reasonable bending parameters, it can ensure that the strip produced by bending has a better shape and better flatness than conventional products.

[0044] 3. In the bottom rolling step (8) of the present invention, the copper alloy is strengthened by introducing shot peening treatment in a specific rolling pass, which not only improves the strength and hardness of the copper alloy strip, but also significantly imparts better anti-softening properties to the strip. Attached Figure Description

[0045] Figure 1 This is a process flow diagram for preparing the low-tin, low-nickel, and low-phosphorus copper alloy strip of the present invention.

[0046] Figure 2 This is a dimensional qualification chart of the copper alloy strip after rough rolling in Example 1 of the present invention;

[0047] Figure 3 This is a dimensional non-compliance pattern of copper alloy strips prepared according to the comparative example of this invention;

[0048] Figure 4 This is a surface scratch diagram of the copper alloy strip prepared in the comparative example of this invention;

[0049] Figure 5 This is a white-gray surface image of the copper alloy strip prepared in the comparative example of this invention;

[0050] Figure 6 This is a diagram showing the bending and straightening of the copper alloy strip prepared according to the comparative example of this invention. Detailed Implementation

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] Unless otherwise specified, all reagents involved in the embodiments of this invention are commercially available products and can be purchased through commercial channels. Unless otherwise specified, all method steps involved in the embodiments of this invention are performed according to conventional processes. Example 1

[0053] The performance requirements for the 0.5H product in this embodiment are: conductivity ≥40% IACS, hardness ≥120HV, tensile strength ≥390MPa, and elongation ≥10%.

[0054] The preparation process flow for low-tin, low-nickel, and low-phosphorus copper alloy strip is as follows: Figure 1 Specifically:

[0055] (1) Raw material ratio: Nickel ingots + tin ingots + electrolytic copper + phosphorus copper alloy is used as raw material, wherein the electrolytic copper composition should meet the national standard for Class A copper chemical composition (GB / T467—2010). The raw materials are prepared according to the alloy composition ratio, and the alloy composition by mass percentage includes: Sn 3.5%, Ni 0.03%, P 0.03%, Pb 0.001%, and the balance is copper.

[0056] (2) Melting and horizontal continuous casting: The material prepared in step (1) is added to the melting furnace for melting. The melting temperature is 1150℃ and the traction speed is 13mm / s. After the composition is qualified by the spectrometer, it is transferred to the holding furnace for horizontal continuous casting to produce a billet with a thickness of 16mm and a width of 450mm.

[0057] (3) Milling: The cast billet produced in step (2) is milled using a milling machine. The upper and lower surfaces of the strip are milled by 1 mm each, and the side surfaces are milled by 1.5 mm each. The milling speed is 3 m / min.

[0058] (4) Rough rolling: The 14mm strip obtained in step (3) is rough rolled in multiple passes using a four-roll mill. The rolling passes are 14-11.5-8.5-6.4-4.9-3.75-2.5-2.0, the rolling speed is 100m / min, the rolling pressure is 5000KN, and the strip is rolled to 2.0mm before being coiled.

[0059] (5) Trimming and rewinding: Trim the strip obtained in step (4) by 15mm on each side, control the trimming speed at 30m / min, and control the rewinding tension at 2800N.

[0060] (6) Bell furnace annealing: The strip obtained in step (5) is subjected to full hydrogen annealing in a bell furnace. The annealing temperature is 400℃, the annealing time is 6h, and the furnace exit temperature is ≤65℃. Vacuuming and protective gas filling are required before exiting the furnace.

[0061] (7) Cleaning: The strip obtained in step (6) is cleaned in a conventional manner at a speed of 35 m / min.

[0062] (8) Rolling with a blank: The strip obtained in step (7) is rolled with a blank, with 2.0-1.35-0.97-0.8-0.7-0.64 rolling passes, 120m / min rolling speed, and 2000KN rolling pressure.

[0063] (9) Air cushion furnace annealing: The strip obtained in step (8) is annealed in an air cushion furnace at a temperature of 550°C and a speed of 24 m / min.

[0064] (10) Finished product rolling: The strip obtained in step (9) is rolled into finished product with a rolling pass of 0.64-0.5 and a rolling speed of 150m / min.

[0065] (11) Finished product cleaning: The strip obtained in step (10) is cleaned. The cleaning medium is 5% dilute sulfuric acid, the passivation solution (Hangzhou Baimu Surface Technology Co., Ltd., HC-09) has a concentration of 0.15%, the passivation solution is used at a temperature of 80℃, and the cleaning speed is 60m / min.

[0066] (12) Finished product tension straightening: The strip obtained in step (11) is subjected to tension straightening with a tension of 18 N / mm before tension straightening. 2 The tension after bending straightening is 17 N / mm. 2 The speed is 150m / min, the elongation is 0.3%, and the plate shape after tension straightening is ≤3I.

[0067] (13) Finished product cutting: The strip obtained in step (12) is cut into finished products, and the width of the strip after cutting is 400mm;

[0068] (14) Packaging and shipping: Pack the strip material obtained in step (13) and ship it to the customer. The surface temperature of the product packaging should be ≤35℃ in winter and ≤40℃ in summer. Example 2

[0069] The performance requirements for the 0.27H product in this embodiment are: conductivity ≥40% IACS, hardness ≥120HV, tensile strength ≥390MPa, and elongation ≥10%.

[0070] The preparation steps for low-tin, low-nickel, and low-phosphorus copper alloy strip are as follows:

[0071] (1) Raw material ratio: Nickel blocks + tin ingots + electrolytic copper + phosphorus copper alloy are used as raw materials. The alloy composition is prepared according to the alloy composition ratio. The alloy composition includes Sn 3.5%, Ni 0.02%, P 0.04%, Pb 0.001% by mass percentage, with the balance being copper.

[0072] (2) Smelting and horizontal continuous casting: The prepared material in step (1) is added to the melting furnace for smelting. The smelting temperature is 1100℃ and the traction speed is 10mm / s. After the composition is qualified by the spectrometer, the copper is transferred to the holding furnace for horizontal continuous casting to produce a billet with a thickness of 16mm and a width of 450mm.

[0073] (3) Milling: The cast billet produced in step (2) is milled using a milling machine. The upper and lower surfaces of the strip are milled by 1 mm each, and the side surfaces are milled by 1.5 mm each. The milling speed is 3 m / min.

[0074] (4) Rough rolling: The 14mm strip obtained in step (3) is rough rolled in multiple passes using a four-roll mill. The rolling passes are 14-11.5-8.5-6.4-4.9-3.75-2.5-2.0-1.5-1.2, the rolling speed is 50m / min, the rolling pressure is 5800KN, and the strip is rolled to 2.0mm before being coiled.

[0075] (5) Trimming and rewinding: Trim the strip obtained in step (4) by 15mm on each side, control the trimming speed at 20m / min, and control the rewinding tension at 3000N.

[0076] (6) Bell furnace annealing: The strip obtained in step (5) is subjected to full hydrogen annealing in a bell furnace. The annealing temperature is 480℃, the annealing time is 6h, and the furnace exit temperature is ≤65℃. Vacuuming and protective gas filling are required before exiting the furnace.

[0077] (7) Cleaning: The strip obtained in step (6) is cleaned in a conventional manner at a speed of 35 m / min.

[0078] (8) Rolling with a blank: The strip obtained in step (7) is rolled with a blank, with 1.2-0.75-0.55-0.4-0.35 rolling passes, 100m / min rolling speed, and 2500KN rolling pressure.

[0079] (9) Air cushion furnace annealing: The strip obtained in step (8) is annealed in an air cushion furnace at a temperature of 550°C and a speed of 24 m / min.

[0080] (10) Finished product rolling: The strip obtained in step (9) is rolled into finished product with a rolling pass of 0.35-0.27 and a rolling speed of 120m / min.

[0081] (11) Finished product cleaning: The strip obtained in step (10) is cleaned. The cleaning medium is dilute sulfuric acid with a mass concentration of 4.5%, the passivation solution (Hangzhou Baimu Surface Technology Co., Ltd., HC-09) has a concentration of 0.1%, the passivation solution is used at a temperature of 70℃, and the cleaning speed is 60m / min.

[0082] (12) Finished product tension straightening: The strip obtained in step (11) is subjected to tension straightening with a tension of 16 N / mm before tension straightening. 2 The tension before and after bending straightening is 16 N / mm. 2 The speed is 100m / min, the elongation is 0.35%, and the plate shape after tension straightening is ≤3I.

[0083] (13) Finished product cutting: The strip obtained in step (12) is cut into finished products, and the width of the strip after cutting is 400mm;

[0084] (14) Packaging and shipping: Pack the strip material obtained in step (13) and ship it to the customer. The surface temperature of the product packaging should be ≤35℃ in winter and ≤40℃ in summer. Example 3

[0085] The performance requirements for the 0.18H product in this embodiment are: conductivity ≥40% IACS, hardness ≥120HV, tensile strength ≥390MPa, and elongation ≥10%.

[0086] The preparation steps for low-tin, low-nickel, and low-phosphorus copper alloy strip are as follows:

[0087] (1) Raw material ratio: Nickel blocks + tin ingots + electrolytic copper + phosphorus copper alloy are used as raw materials. The alloy composition is prepared according to the alloy composition ratio. The alloy composition includes Sn 3.0%, Ni 0.04%, P 0.04%, Pb 0.001% by mass percentage, with the balance being copper.

[0088] (2) Smelting and horizontal continuous casting: The prepared material in step (1) is added to the melting furnace for smelting. The smelting temperature is 1200℃ and the traction speed is 16mm / s. After the composition is qualified by the spectrometer, the copper is transferred to the holding furnace for horizontal continuous casting to produce a billet with a thickness of 16mm and a width of 450mm.

[0089] (3) Milling: The cast billet produced in step (2) is milled using a milling machine. The upper and lower surfaces of the strip are milled by 1 mm each, and the side surfaces are milled by 1.5 mm each. The milling speed is 3 m / min.

[0090] (4) Rough rolling: The 14mm strip obtained in step (3) is rough rolled in multiple passes using a four-roll mill. The rolling passes are 14-11.5-8.5-6.4-4.9-3.75-2.5-2.0-1.5-1.2, the rolling speed is 150m / min, the rolling pressure is 4500KN, and the strip is rolled to 2.0mm before being coiled.

[0091] (5) Trimming and rewinding: Trim the strip obtained in step (4) by 15mm on each side, control the trimming speed at 45m / min, and control the rewinding tension at 2500N.

[0092] (6) Bell furnace annealing: The strip obtained in step (5) is subjected to full hydrogen annealing in a bell furnace. The annealing temperature is 480℃, the annealing time is 6h, and the furnace exit temperature is ≤65℃. Vacuuming and protective gas filling are required before exiting the furnace.

[0093] (7) Cleaning: The strip obtained in step (6) is cleaned in a conventional manner at a speed of 35 m / min.

[0094] (8) Rolling with a blank: The strip obtained in step (7) is rolled with a blank, with 1.2-0.75-0.55-0.4-0.32-0.27-0.23 rolling passes, 150m / min rolling speed, and 1500KN rolling pressure.

[0095] (9) Air cushion furnace annealing: The strip obtained in step (8) is annealed in an air cushion furnace at a temperature of 650°C and a speed of 38 m / min.

[0096] (10) Finished product rolling: The strip obtained in step (9) is rolled into finished product with 0.23-0.18 rolling passes and a rolling speed of 180m / min.

[0097] (11) Finished product cleaning: The strip obtained in step (10) is cleaned. The cleaning medium is dilute sulfuric acid with a mass concentration of 6.5%, the passivation solution (Hangzhou Baimu Surface Technology Co., Ltd., HC-09) has a concentration of 0.2%, the passivation solution is used at a temperature of 90℃, and the cleaning speed is 60m / min.

[0098] (12) Finished product tension straightening: The strip obtained in step (11) is subjected to tension straightening with a tension of 20 N / mm before tension straightening. 2 The tension after bending straightening is 20 N / mm. 2 The speed is 200m / min, the elongation is 0.4%, and the plate shape after tension straightening is ≤3I.

[0099] (13) Finished product cutting: The strip obtained in step (12) is cut into finished products, and the width of the strip after cutting is 400mm;

[0100] (14) Packaging and shipping: Pack the strip material obtained in step (13) and ship it to the customer. The surface temperature of the product packaging should be ≤35℃ in winter and ≤40℃ in summer. Example 4

[0101] Based on Example 1, this example provides a preparation procedure for a low-tin, low-nickel, and low-phosphorus copper alloy strip. Shot peening is also included before the second and third rolling passes in step (8) of the bottom rolling process. Specifically:

[0102] (1) Raw material ratio: Nickel blocks + tin ingots + electrolytic copper + phosphorus copper alloy are used as raw materials. The alloy composition is prepared according to the alloy composition ratio. The alloy composition includes Sn 3.5%, Ni 0.03%, P 0.03%, Pb 0.001% by mass percentage, with the balance being copper.

[0103] (2) Melting and horizontal continuous casting: The material prepared in step (1) is added to the melting furnace for melting. The melting temperature is 1150℃ and the traction speed is 13mm / s. After the composition is qualified by the spectrometer, it is transferred to the holding furnace for horizontal continuous casting to produce a billet with a thickness of 16mm and a width of 450mm.

[0104] (3) Milling: The cast billet produced in step (2) is milled using a milling machine. The upper and lower surfaces of the strip are milled by 1 mm each, and the side surfaces are milled by 1.5 mm each. The milling speed is 3 m / min.

[0105] (4) Rough rolling: The 14mm strip obtained in step (3) is rough rolled in multiple passes using a four-roll mill. The rolling passes are 14-11.5-8.5-6.4-4.9-3.75-2.5-2.0, the rolling speed is 100m / min, the rolling pressure is 5000KN, and the strip is rolled to 2.0mm before being coiled.

[0106] (5) Trimming and rewinding: Trim the strip obtained in step (4) by 15mm on each side, control the trimming speed at 30m / min, and control the rewinding tension at 2800N.

[0107] (6) Bell furnace annealing: The strip obtained in step (5) is subjected to full hydrogen annealing in a bell furnace. The annealing temperature is 400℃, the annealing time is 6h, and the furnace exit temperature is ≤65℃. Vacuuming and protective gas filling are required before exiting the furnace.

[0108] (7) Cleaning: The strip obtained in step (6) is cleaned in a conventional manner at a speed of 35 m / min.

[0109] (8) Rolling with a blank: The strip obtained in step (7) is rolled with a blank, with 2.0-1.35-0.97-0.8-0.7-0.64 rolling passes, 120m / min rolling speed, and 2000KN rolling pressure.

[0110] Before the second and third rolling passes, shot peening is performed using metal shot. For the shot peening before the second rolling pass, the shot diameter is 0.8 mm, the peening pressure is 0.7 MPa, and the peening time is 10 min. For the shot peening before the third rolling pass, the shot diameter is 0.4 mm, the peening pressure is 0.45 MPa, and the peening time is 18 min.

[0111] (9) Air cushion furnace annealing: The strip obtained in step (8) is annealed in an air cushion furnace at a temperature of 550°C and a speed of 24 m / min.

[0112] (10) Finished product rolling: The strip obtained in step (9) is rolled into finished product with a rolling pass of 0.64-0.5 and a rolling speed of 150m / min.

[0113] (11) Finished product cleaning: The strip obtained in step (10) is cleaned. The cleaning medium is 5% dilute sulfuric acid, the passivation solution (Hangzhou Baimu Surface Technology Co., Ltd., HC-09) has a concentration of 0.15%, the passivation solution is used at a temperature of 80℃, and the cleaning speed is 60m / min.

[0114] (12) Finished product tension straightening: The strip obtained in step (11) is subjected to tension straightening with a tension of 18 N / mm before tension straightening. 2 The tension after bending straightening is 17 N / mm. 2 The speed is 150m / min, the elongation is 0.3%, and the plate shape after tension straightening is ≤3I.

[0115] (13) Finished product cutting: The strip obtained in step (12) is cut into finished products, and the width of the strip after cutting is 400mm;

[0116] (14) Packaging and shipping: Pack the strip material obtained in step (13) and ship it to the customer. The surface temperature of the product packaging should be ≤35℃ in winter and ≤40℃ in summer. Example 5

[0117] This embodiment provides a method for preparing low-tin, low-nickel, and low-phosphorus copper alloy strip. Step (8) of this embodiment includes shot peening before the second and third rolling passes, using metal shot. Before the second rolling pass, the shot diameter is 0.6 mm, the peening pressure is 0.8 MPa, and the peening time is 8 min. Before the third rolling pass, the shot diameter is 0.3 mm, the peening pressure is 0.5 MPa, and the peening time is 15 min.

[0118] The rest is the same as in Example 4. Example 6

[0119] This embodiment provides a preparation process for a low-tin, low-nickel, and low-phosphorus copper alloy strip. Step (8) of this embodiment includes shot peening before the second and third rolling passes, using metal shot. Before the second rolling pass, the shot diameter is 1 mm, the peening pressure is 0.65 MPa, and the peening time is 14 min. Before the third rolling pass, the shot diameter is 0.5 mm, the peening pressure is 0.4 MPa, and the peening time is 20 min.

[0120] The rest is the same as in Example 4.

[0121] Comparative Example 1

[0122] The difference between this comparative example and Example 1 is that the rolling pressure of the rough rolling in step (4) is 3000KN.

[0123] Comparative Example 2

[0124] The difference between this comparative example and Example 1 is that the rolling pressure of the rough rolling in step (4) is 6000KN.

[0125] Comparative Example 3

[0126] The difference between this comparative example and Example 1 is that the rolling speed of the rough rolling in step (4) is 30 m / min.

[0127] Comparative Example 4

[0128] The difference between this comparative example and Example 1 is that the rolling speed of the rough rolling in step (4) is 200 m / min.

[0129] Comparative Example 5

[0130] The difference between this comparative example and Example 1 is that the rolling speed of the bottom rolling in step (8) is 80m / min.

[0131] Comparative Example 6

[0132] The difference between this comparative example and Example 1 is that the rolling speed of the bottom rolling in step (8) is 200m / min.

[0133] Comparative Example 7

[0134] The difference between this comparative example and Example 1 is that the cleaning medium used in step (11) of cleaning the finished product is sulfuric acid with a mass percentage of 3%.

[0135] Comparative Example 8

[0136] The difference between this comparative example and Example 1 is that the cleaning medium used in step (11) of cleaning the finished product is sulfuric acid with a mass percentage of 8%.

[0137] Comparative Example 9

[0138] The difference between this comparative example and Example 1 is that the passivation solution used for cleaning the finished product in step (11) is passivation solution HC-09 with a mass percentage of 0.08%.

[0139] Comparative Example 10

[0140] The difference between this comparative example and Example 1 is that the passivation solution used for cleaning the finished product in step (11) is passivation solution HC-09 with a mass percentage of 0.25%.

[0141] Comparative Example 11

[0142] The difference between this comparative example and Example 1 is that the tension before and after the bending straightening of the finished product in step (12) is 15 N / mm. 2 .

[0143] Comparative Example 12

[0144] The difference between this comparative example and Example 1 is that the tension before and after the bending straightening of the finished product in step (12) is 22 N / mm. 2 .

[0145] Comparative Example 13

[0146] The difference between this comparative example and Example 1 is that the bending speed of the finished product in step (12) is 80m / min.

[0147] Comparative Example 14

[0148] The difference between this comparative example and Example 1 is that the bending speed of the finished product in step (12) is 220m / min.

[0149] Comparative Example 15

[0150] The difference between this comparative example and Example 4 is that shot peening is performed before the second and third rolling passes in the rough rolling step (4), and the shot peening steps are the same as in Example 4.

[0151] Comparative Example 16

[0152] The difference between this comparative example and Example 4 is that shot peening is performed before the first rolling pass in step (10) of finished product rolling. The shot peening process is as follows: the diameter of the shot is 0.8 mm, the shot peening pressure is 0.7 MPa, and the shot peening time is 10 min.

[0153] Comparative Example 17

[0154] The difference between this comparative example and Example 4 is that shot peening is performed before the first and second rolling passes in the (8) bottom rolling step. The shot peening steps are the same as those in Example 4.

[0155] Comparative Example 18

[0156] The difference between this comparative example and Example 4 is that, in the bottom rolling step (8), the diameter of the shot during the shot peening treatment before the second rolling pass is 0.4 mm, the shot peening pressure is 0.5 MPa, and the shot peening time is 6 min.

[0157] Comparative Example 19

[0158] The difference between this comparative example and Example 4 is that, in the bottom rolling step (8), the diameter of the shot during the shot peening treatment before the second rolling pass is 1.2 mm, the shot peening pressure is 1.0 MPa, and the shot peening time is 25 min.

[0159] Comparative Example 20

[0160] The difference between this comparative example and Example 4 is that, in the bottom rolling step (8), the diameter of the shot is 0.2 mm, the shot peening pressure is 0.2 MPa, and the shot peening time is 12 min before the third rolling pass.

[0161] Comparative Example 21

[0162] The difference between this comparative example and Example 4 is that, in the bottom rolling step (8), the diameter of the shot is 0.7 mm, the shot peening pressure is 0.7 MPa, and the shot peening time is 22 min before the third rolling pass.

[0163] I. Product Appearance

[0164] Copper alloy strip products were prepared according to the methods of Examples 1-6 and Comparative Examples 1-14 of this invention, and their appearance was observed. The results are as follows:

[0165] The copper alloy strip products obtained in Examples 1-6 have normal appearances and no abnormalities, and the thickness dimensions of the products after rough rolling are qualified. Taking Example 1 as an example, the thickness dimension map of the product after rough rolling is shown. Figure 2 As can be seen, the product thickness curve (light-colored line) is within the allowable range (black layer).

[0166] The copper alloy strip products obtained in Comparative Examples 1-4 had normal appearances, but the thickness of the products after rough rolling was unqualified, such as... Figure 3 As shown, the product thickness curve (light-colored line) exceeds the allowable range (black layer), indicating poor product dimensions.

[0167] The copper alloy strip products prepared in Comparative Examples 5-6 showed thermal scratches on their surface, such as... Figure 4 As shown, some scratches are visible.

[0168] The copper alloy strip products prepared in Comparative Examples 7-10 showed a white-gray surface, such as... Figure 5 As shown, the finished product was not thoroughly cleaned.

[0169] The copper alloy strip products obtained in Comparative Examples 11-14 could not be straightened by tensile bending straightening, such as... Figure 6 As shown, the surface of the product after bending and straightening is uneven and cannot be straightened.

[0170] II. Product Performance Testing

[0171] 1. Basic performance

[0172] The copper alloy strip products obtained in Examples 1-6 of this invention were subjected to basic performance tests, and the results are shown in Table 1 below.

[0173] Table 1

[0174]

[0175] As shown in Table 1, the copper alloy strip products obtained in embodiments 1-6 of this invention all meet the basic performance requirements of conductivity ≥40% IACS, hardness ≥120HV, tensile strength ≥390MPa, and elongation ≥10%.

[0176] Comparing Examples 1 and 4, it can be seen that the specific shot peening treatment performed in the bottom rolling step of Example 4 of the present invention can significantly improve the strength and hardness of the product.

[0177] 2. Softening resistance

[0178] The copper alloy strip products obtained in Examples 1 and 4 and Comparative Examples 15-21 of this invention were subjected to softening resistance tests. The high-temperature softening temperature of the products was specifically tested, and the results are shown in Table 2.

[0179] Table 2

[0180]

[0181] As shown in Table 2, compared with the previous embodiment, after performing a specific shot peening treatment in the bottom rolling step of the present invention, the softening temperature of the product can be increased and the softening resistance is improved.

[0182] Compared with Example 4, Comparative Examples 15-21 changed the shot peening process, resulting in a decrease in the resistance to softening.

[0183] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of producing a low-tin, low-nickel, low-phosphorus copper alloy strip, characterized by: Includes the following steps: (1) Batching; (2) Smelting and horizontal continuous casting; (3) Milling; (4) Rough rolling; (5) Trimming and rewinding; (6) Bell furnace annealing; (7) Cleaning; (8) Rolling with bottom residue; (9) Air cushion furnace annealing; (10) Finished product rolling; (11) Finished product cleaning; (12) Finished product stretching and straightening; (13) Finished product slitting; (14) Packaging and shipping; Step (4) The rolling speed of the rough rolling is 50-150 m / min, and the rolling pressure is 4500-5800 KN; The rolling speed for step (8) of the bottom rolling is 100-150 m / min; Step (11) The cleaning medium used for cleaning the finished product is sulfuric acid with a mass percentage of 4.5-6.5%, and the passivation solution used is passivation solution HC-09 with a mass percentage of 0.1-0.2%. Step (12) The tension before and after the finished product bending straightening is 16-20 N / mm. 2 The speed is 100-200 m / min; The composition of the copper alloy strip, by mass percentage, includes: 1-4% tin, 0.01-0.06% nickel, 0.01-0.05% phosphorus, with the balance being copper and unavoidable impurities, wherein unavoidable impurities are ≤0.05%. Step (8) The total processing rate of the bottom rolling is 60-85%, the rolling passes are 4-6, and the second and third rolling passes are shot peening. The diameter of the shot is 0.3-1mm, the shot peening pressure is 0.4-0.8MPa, and the shot peening time is 8-20min.

2. The method for preparing low-tin, low-nickel, and low-phosphorus copper alloy strip according to claim 1, characterized in that: Step (4) The total processing rate of rough rolling is 85-92%, and the number of rolling passes is 7-9.

3. The method of producing low-tin, low-nickel, low-phosphorus copper alloy strip according to claim 1, characterized by: The total processing rate of the finished product rolling in step (10) is 20-30%.

4. The method of producing low-tin, low-nickel, low-phosphorus copper alloy strip of claim 1, wherein: Step (2) The melting temperature is 1100-1200℃ and the traction speed is 10-16mm / s; Step (5) The cutting speed for edge cutting and rewinding is 20-45 m / min, and the rewinding tension is 2500-3000 N; Step (6) The annealing temperature of the bell furnace is 400-500℃ and the annealing time is 6-8h; Step (9) The annealing temperature of the air cushion furnace is 500-700℃, and the annealing speed is 20-50 m / min; The rolling speed for step (10) of finished product rolling is 120-180 m / min; The cleaning speed of the finished product in step (11) is 20-80 m / min.

5. The method of producing low-tin, low-nickel, low-phosphorus copper alloy strip of claim 1, wherein: Step (8) The processing rate of the second rolling pass of the bottom rolling is 25-30%. The diameter of the shot during shot peening is 0.6-1mm, the shot peening pressure is 0.65-0.8MPa, and the shot peening time is 8-14min.

6. The method for preparing low-tin, low-nickel, and low-phosphorus copper alloy strip according to claim 1, characterized in that: Step (8) The processing rate of the third rolling pass of the bottom rolling is 15-28%. The diameter of the shot during shot peening is 0.3-0.5mm, the shot peening pressure is 0.4-0.5MPa, and the shot peening time is 15-20min.

7. A low-tin, low-nickel, and low-phosphorus copper alloy strip prepared by the preparation method according to any one of claims 1-6.

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