Copper strip preparation process capable of eliminating processing residual stress and copper strip

Abstract

The invention relates to a copper strip preparation technology capable of eliminating machining residual stress and a copper strip, in the preparation process, two times of vibration aging treatment are carried out, the first time is cast ingot vibration aging treatment before cast ingot hot rolling, and the second time is finished strip vibration aging treatment after finished product rolling; the technological parameters of the cast ingot vibration aging treatment are as follows: the excitation frequency is 10-150Hz, the excitation force is less than or equal to 20KN, and the aging time is less than or equal to 60 minutes; the process parameters of the vibration aging treatment of the finished strip are as follows: the excitation frequency is 10-150Hz, the excitation force is less than or equal to 20KN, and the aging time is less than or equal to 60 minutes. The machining residual stress of the copper strip can be effectively reduced through two times of vibration aging treatment, the stamping and etching performance of the material is improved, meanwhile, the tensile strength, the electric conductivity and the like of the strip are not changed, and the final performance requirement of a product is met.

Description

Technical Field

[0001] The invention belongs to the field of nonferrous metal processing, and in particular relates to a copper strip preparation process and a copper strip capable of eliminating processing residual stress. Background Art

[0002] Copper and copper alloys have the characteristics of high electrical conductivity, high thermal conductivity, corrosion resistance, suitable strength, easy processing and forming, etc. Their application range is very wide, involving almost every field of human life. The main uses of copper and copper alloys are connectors for power electronics, integrated circuit lead frames, heat exchanger plates, mechanical structural parts, liquid pipelines, ship guard plates, etc.

[0003] The processing of copper and copper alloy strips involves a variety of processing and forming methods such as casting and rolling. During the processing, there will inevitably be large residual stress. Due to the existence of residual stress, the strip will be deformed due to stress release during stamping, etching and other processes, and qualified integrated circuit lead frames, electronic connectors, mechanical structural parts, etc. cannot be produced.

[0004] Therefore, eliminating or controlling the residual stress of copper and copper alloy strips is crucial for the forming and processing of products such as connectors, lead frames, and structural parts. Summary of the invention

[0005] The purpose of the present invention is to provide a copper strip preparation process and a copper strip capable of eliminating processing residual stress. Through process improvement, on the one hand, cooling stress, solidification stress, chemical stress, etc. formed in the ingot production process are eliminated, the quality of the ingot is improved, the probability of edge cracks and surface cracks in the ingot after hot rolling is reduced, and the heating time of the ingot is reduced; on the other hand, without reducing the tensile strength and electrical conductivity of the material, the copper strip has a lower residual stress, thereby being better suitable for stamping, etching and the like of the material.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: a copper strip preparation process capable of eliminating processing residual stress, wherein two vibration aging treatments are performed during the preparation process, the first being the ingot vibration aging treatment before ingot hot rolling, and the second being the finished strip vibration aging treatment after finished product rolling; The process parameters of the ingot vibration aging treatment are: excitation frequency of 10-150 Hz, excitation force ≤ 20 KN, aging time ≤ 60 minutes; The process parameters of the vibration aging treatment of the finished strip are: the excitation frequency is 10-150 Hz, the excitation force is ≤20 KN, and the aging time is ≤60 minutes.

[0007] The process parameters of the ingot vibration aging treatment are: excitation frequency of 90 Hz, excitation force of 12 KN, and aging time of 25 minutes; the process parameters of the finished strip aging treatment are: excitation frequency of 80 Hz, excitation force of 10 KN, and aging time of 20 minutes.

[0008] The process parameters of the ingot vibration aging treatment are: excitation frequency of 150 Hz, excitation force of 20 KN, and aging time of 60 minutes; the process parameters of the finished strip aging treatment are: excitation frequency of 150 Hz, excitation force of 20 KN, and aging time of 60 minutes.

[0009] The process parameters of the ingot vibration aging treatment are: excitation frequency of 10 Hz, excitation force of 5 KN, and aging time of 10 minutes; the process parameters of the finished strip aging treatment are: excitation frequency of 10 Hz, excitation force of 5 KN, and aging time of 10 minutes.

[0010] Another embodiment of the present invention: A copper strip preparation process capable of eliminating processing residual stress, comprising the following steps: a first step, melting the prepared raw materials, the melt temperature is 1100-1300°C; semi-continuous casting is adopted, borax, carbon black or protective gas is used to cover the melt in the crystallizer, the casting speed is 2-12 m / h; the cooling water flow rate is 100-1000 L / min; The second step is to perform vibration aging treatment on the ingot, using the process parameters of the vibration aging treatment on the ingot in the copper strip preparation process described above; The third step is to heat the ingot after the previous step, the heating temperature is 800-980°C, and the homogenization annealing time is 4-9 hours; the hot rolling is carried out, the total processing rate of the hot-rolled strip is 90%-97%, the total number of passes is 7-13, the hot rolling final rolling temperature is 650-750°C, and the last pass is online solid solution; The fourth step is to perform strip milling and edge milling on the hot-rolled strip coil on a double-sided milling machine, with a milling speed of 8 to 20 m / min and a milling amount of 0.2 to 1.0 mm / face; The fifth step is to perform blank rolling on the milled hot-rolled coil on the rolling mill, with 7 to 12 rolling passes and an average rolling speed of 350 m / min. Step 6: Shear the edges of the rolled strip on a shearing device; The seventh step is to perform aging annealing on the copper strip after edge trimming, the annealing temperature is 400-600°C, and the insulation time is 3-10 hours; The eighth step is to remove the surface oxide scale and passivate the copper strip. Use dilute sulfuric acid to clean the surface oxide scale of the copper strip; use passivation liquid to passivate the surface of the copper strip, and keep the passivation working temperature at 60-80°C; The ninth step is to carry out finished product rolling in a finishing mill at a rolling speed of 80 to 600 m / min; The tenth step is to degrease and passivate the surface of the finished copper strip, use a degreasing agent to clean the surface grease, use a passivation liquid to passivate the surface, and keep the passivation working temperature at 50-80°C; Step 11: vibratory aging treatment of the finished strip, using the process parameters of the vibratory aging treatment of the finished strip in the above copper strip preparation process; The twelfth step is to take samples for performance testing. After passing the test, the finished copper strips are cut, packaged and put into storage.

[0011] Furthermore, in the fifth step of slab rolling, the processing rate of the last pass is controlled to be 6%, and the rolling coiling tension is 40KN.

[0012] Furthermore, in the eighth step, the concentration of dilute sulfuric acid is 5% to 20%, the passivation solution is benzotriazole, and the concentration of the passivation solution is 3 to 6‰.

[0013] Furthermore, in the tenth step, the concentration of the degreasing agent is 0.5-5%, the passivation solution is benzotriazole, and the concentration of the passivation solution is 3-6‰.

[0014] The present invention also provides a copper strip, which is prepared by the preparation process as described above.

[0015] The technical principle of the present invention is analyzed as follows: The copper strip described in the present invention refers to copper strip or copper alloy strip. Since copper or copper alloy strip products have high tensile strength, the products generally have a large rolling processing rate during processing and production, resulting in a more obvious work hardening phenomenon in the material, which significantly increases the point defects and dislocation density inside the material, causing the residual stress of the material to increase sharply. Therefore, during the processing of copper or copper alloy strip, internal residual stress will inevitably exist. Due to the existence of residual stress, the strip will be deformed due to stress release during stamping, etching and other processing, and qualified integrated circuit lead frames, electronic connectors, mechanical structural parts, etc. cannot be produced.

[0016] Vibration aging is a technology that eliminates and homogenizes the residual stress inside metal materials by vibration, which can effectively reduce the residual internal stress caused by casting or rolling processes. Vibration aging treatment uses equipment such as exciters and control boxes, as well as accessories such as fixtures and sensors, to produce microscopic plastic deformation inside the workpiece under resonance, thereby reducing and homogenizing the internal residual stress.

[0017] From a microscopic perspective, vibration aging can be considered as an additional stress applied to a part in the form of a cyclic load. When the workpiece is vibrated, the alternating stress applied to the part is superimposed on the residual stress in the part. When the result of the stress superposition reaches a certain value, the yield limit of the material will be exceeded at the most serious stress concentration point, and microscopic plastic deformation will occur, causing the distorted lattice to gradually return to a state of equilibrium, and the dislocations will re-slip and pin, thereby eliminating and equalizing the residual stress inside the workpiece.

[0018] The beneficial effect of the present invention is that in the process of preparing copper or copper alloy strips, the present invention mainly performs vibration aging treatment on the cast ingot and the finished strip after rolling, respectively, to eliminate the residual stress in the processed material. The "eliminating" residual stress in the present invention refers to reducing the residual stress in the material so that the residual stress does not affect the subsequent product processing, such as stamping, etching, etc.

[0019] After the ingot casting is completed, the vibration aging treatment can eliminate 30%-60% of the casting residual stress. After the vibration aging treatment of the finished strip after rolling, the residual stress of the strip can be eliminated by 40%-50%. It has lower residual stress, thereby improving the stamping and etching applicability of the material. At the same time, the tensile strength and conductivity of the strip have not changed, meeting the final performance requirements of the product and achieving the expected purpose. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with the embodiments, but they are not intended to limit the invention in any way.

[0021] Example 1: In this example, a C19400 ingot is first produced, with a weight of 10 tons, a hot-rolled thickness of 16 mm, and a state of R. The hot-rolled coil is required to have a tensile strength of more than 280 MPa, a conductivity of more than 20% IACS, no cracks after hot rolling, and qualified quality.

[0022] Then, after the hot-rolled coil is cold-processed, the C19400 strip produced has a specification of 0.2×50mm. The final product has a tensile strength between 430 and 440MPa, a conductivity of 60 to 65%IACS, and a residual stress of less than 60MPa.

[0023] The C19400 strip prepared in this embodiment uses the copper strip preparation process capable of eliminating processing residual stress described in the present invention, and its process flow includes: smelting, semi-continuous casting, vibration aging, heating, hot rolling, strip milling, initial rolling, trimming, annealing, pickling, finished product rolling, cleaning, vibration aging, performance testing, shearing and warehousing.

[0024] The specific steps are as follows: Step 1: Melting and Casting Weigh and place the configured standard cathode copper, old materials of this brand, small metals, etc. into a 10 t melting furnace for non-vacuum melting, and cover them with a mixture of graphite powder and dehydrated charcoal with a thickness of not less than 200 mm. The melting furnace uses electric heating to melt into a molten liquid at 1300°C. In order to ensure the quality of the molten liquid, the raw materials and covering agents used must be dry and oil-free; After melting, the melt is placed in a holding furnace for static standing, which is conducive to the slag of oxides and carbides in the melt to float up. The floating slag is removed to purify the melt. The melt after static standing and slag removal is sampled and analyzed, and the composition is adjusted to ensure that the melt composition is qualified. The main components of the melt are: Cu content 97.21%, Fe content 2.5%, P content 0.135%, Zn content 0.15%, Pb content 0.005%; Semi-continuous casting is adopted, and borax, carbon black, or protective gas is used to cover the melt in the crystallizer during casting; the casting speed is 12m / h; the cooling water flow rate is 900 L / min; The width of the cast ingot is 600mm and the thickness is 260mm. This width-to-thickness ratio is conducive to the stable casting of the ingot and the floating of the slag. When the ingot length required by the strip is reached, the casting is stopped. After sawing, a C19400 ingot weighing 10 tons was obtained; the residual stress of the ingot was between 18 and 22 MPa.

[0025] The second step is vibration aging The main process parameters involved in vibration aging are: excitation frequency, excitation force, and effective time. When performing vibration aging on C19400 ingots, the excitation frequency is selected as 90HZ, the excitation force is 12KN, and after 25 minutes of effective time, the casting residual stress of the C19400 ingot is between 7.2 and 9.8MPa, and the casting residual stress reduction value is as high as 60%, which provides favorable conditions for the homogenization annealing and hot rolling of the ingot.

[0026] The third step is heating and hot rolling The ingot is heated by a walking-beam heating furnace at a heating temperature of 950°C and homogenized for 6 hours; it is then taken out of the furnace for hot rolling, with a final thickness of 16.0 mm, a total processing rate of 92.6% for the hot-rolled strip, 11 rolling passes, a final hot rolling temperature of 700°C, and an online solution process in the last pass.

[0027] After hot rolling, the tensile strength of the coil is 295MPa, the conductivity is 26%IACS, there is no edge crack on the surface of the coil, the quality is qualified, the lateral tolerance of the coil is within 0.05mm, and the dimensional accuracy is good; the plate shape of the coil is between 90 and 100I, and the plate shape is good.

[0028] The fourth step is milling: the hot-rolled strip is milled on the double-sided milling machine. The milling cutter speed is 900r / min, the milling speed is 20m / min, and there is no missed milling, no oxidation pits, and no sticky chips on the surface.

[0029] The fifth step is the initial rolling: the hot rolled strip coil after milling is subjected to the initial rolling on a four-roll initial rolling mill. The rolling process is 10 times with an average rolling speed of 350 m / min. Emulsion lubrication is used during the rolling process.

[0030] During the rolling process, controlling the last pass processing rate to 6% and the rolling coiling tension to 40KN is one of the effective means to control the strip thickness tolerance and rolled plate shape.

[0031] Step 6, trimming: trim the edges of the rolled strip on the shearing equipment to remove burrs and rough edges. The trimming width is 40mm and the trimming speed is 250m / min. The uncoiling and coiling tension is adjusted by a loop method to avoid surface scratches caused by excessive changes in front and back tension.

[0032] The seventh step is bell annealing: the copper strip is subjected to aging annealing treatment in a bell furnace at a temperature of 600°C and a holding time of 10 hours. After aging treatment, the C19400 alloy fully precipitates the second phase, which greatly improves the strength of the material while also having suitable electrical conductivity.

[0033] The eighth step is pickling: remove the surface oxide scale and passivate the copper strip. Use 20% dilute sulfuric acid to clean the surface oxide scale of the copper strip; use a passivation solution with a concentration of 6‰ to passivate the surface of the copper strip. The passivation working temperature is maintained at 80°C, and the passivation solution is benzotriazole.

[0034] The ninth step is finished product rolling: the thickness of the final rolled product is 0.2mm. To ensure product performance, the finished product processing rate is 40%. The residual stress value of the obtained product is between 80 and 90MPa, the tensile strength of the obtained product is between 430 and 440MPa, and the conductivity of the obtained product is between 60 and 65%IACS.

[0035] The tenth step, cleaning: degrease and passivate the surface of the finished copper strip, use a 5% degreaser to clean the surface grease, use a 6‰ passivation liquid to passivate the surface, the passivation working temperature is maintained at 80°C, and the passivation liquid is benzotriazole.

[0036] Step 11, vibration aging: Use fixtures and connecting wires to connect the wound strip to the vibration aging equipment, select 80HZ for the excitation frequency, 10KN for the excitation force, and 20 minutes for the effective time. The residual stress value of the obtained product is between 40 and 49MPa, the tensile strength of the obtained product is between 430 and 440MPa, and the conductivity of the obtained product is between 60 and 65%IACS. Compared with the finished strip after finished rolling, the residual stress of the final product is greatly reduced after vibration aging, and the residual stress of the strip is eliminated by 50%, while the tensile strength and conductivity do not change.

[0037] Step 12, performance testing and finished product cutting: sampling for performance testing. The material performance indicators meet the user's requirements. After that, the finished copper strip is cut and the strip is cut into 50mm width. The strip width tolerance, roll weight, etc. are implemented according to the contract requirements. After passing the inspection, it is packaged and stored.

[0038] In this embodiment, a vibration aging process for ingots and a vibration aging process for finished strips are added to the process route. After the vibration aging treatment of the ingots, the casting residual stress is eliminated by 60%, so that the shape of the hot-rolled strip coil is improved while meeting the tensile strength and electrical conductivity requirements after hot rolling; after the vibration aging treatment of the finished strip, the tensile strength and electrical conductivity of the material remain unchanged, the residual stress of the copper strip is eliminated by 50%, and the stamping and etching applicability of the material is improved.

[0039] Example 2: In this example, a C19400 ingot is first produced, with a weight of 10 tons, a hot-rolled thickness of 16 mm, and a state of R. The hot-rolled coil is required to have a tensile strength of more than 280 MPa, a conductivity of more than 20% IACS, no cracks after hot rolling, and qualified quality.

[0040] Then, after the hot-rolled coil is cold-processed, the C19400 strip produced has a specification of 0.2×50mm. The final product has a tensile strength between 430 and 440MPa, a conductivity of 60 to 65%IACS, and a residual stress of less than 60MPa.

[0041] The C19400 strip prepared in this embodiment uses the copper strip preparation process capable of eliminating processing residual stress described in the present invention, and its process flow includes: smelting, semi-continuous casting, heating, hot rolling, strip coil milling, initial rolling, trimming, annealing, pickling, finished product rolling, cleaning, vibration aging, performance testing, shearing and warehousing.

[0042] The specific steps are as follows: Step 1: Melting and Casting Weigh and place the configured standard cathode copper, old materials of this brand, small metals, etc. into a 10 t melting furnace for non-vacuum melting, and cover them with a mixture of graphite powder and dehydrated charcoal with a thickness of not less than 200 mm. The melting furnace uses electric heating to melt into a molten liquid at 1300°C. In order to ensure the quality of the molten liquid, the raw materials and covering agents used must be dry and oil-free; After melting, the melt is placed in a holding furnace for static standing, which is conducive to the slag of oxides and carbides in the melt to float up. The floating slag is removed to purify the melt. The melt after static standing and slag removal is sampled and analyzed, and the composition is adjusted to ensure that the melt composition is qualified. The main components of the melt are: Cu content 97.21%, Fe content 2.5%, P content 0.135%, Zn content 0.15%, Pb content 0.005%; Semi-continuous casting is adopted, and borax, carbon black, or protective gas is used to cover the melt in the crystallizer during casting; casting speed is 12m / h; cooling water flow rate: 900 L / min; The width of the cast ingot is 600mm and the thickness is 260mm. This width-to-thickness ratio is conducive to the stable casting of the ingot and the floating of the slag. When the ingot length required by the strip is reached, the casting is stopped. After sawing, a C19400 ingot weighing 10 tons was obtained; the residual stress of the ingot was between 18 and 22 MPa.

[0043] The second step is vibration aging The main process parameters involved in vibration aging are: excitation frequency, excitation force, and effective time. When performing vibration aging on C19400 ingots, the excitation frequency is selected as 150HZ, the excitation force is 20KN, and after 60 minutes of effective time, the casting residual stress of the C19400 ingot is between 7.2 and 9.8MPa, and the casting residual stress reduction value is as high as 60%, which provides favorable conditions for the homogenization annealing and hot rolling of the ingot.

[0044] The third step is heating and hot rolling The ingot is heated by a walking-beam heating furnace at a heating temperature of 950°C and homogenized for 6 hours; it is then taken out of the furnace for hot rolling, with a final thickness of 16.0 mm, a total processing rate of 92.6% for the hot-rolled strip, 11 rolling passes, a final hot rolling temperature of 700°C, and an online solution process in the last pass.

[0045] After hot rolling, the tensile strength of the coil is 295MPa, the conductivity is 26%IACS, there is no edge crack on the surface of the coil, the quality is qualified, the lateral tolerance of the coil is within 0.05mm, and the dimensional accuracy is good; the plate shape of the coil is between 90 and 100I, and the plate shape is good.

[0046] The fourth step is milling: the hot-rolled strip is milled on the double-sided milling machine. The milling cutter speed is 900r / min, the milling speed is 20m / min, and there is no missed milling, no oxidation pits, and no sticky chips on the surface.

[0047] The fifth step is the initial rolling: the hot rolled strip coil after milling is subjected to the initial rolling on a four-roll initial rolling mill. The rolling process is 10 times with an average rolling speed of 350 m / min. Emulsion lubrication is used during the rolling process.

[0048] During the rolling process, controlling the last pass processing rate to 6% and the rolling coiling tension to 40KN is one of the effective means to control the strip thickness tolerance and rolled plate shape.

[0049] Step 6, trimming: trim the edges of the rolled strip on the shearing equipment to remove burrs and rough edges. The trimming width is 40mm and the trimming speed is 250m / min. The uncoiling and coiling tension is adjusted by a loop method to avoid surface scratches caused by excessive changes in front and back tension.

[0050] The seventh step is bell annealing: the copper strip is subjected to aging annealing treatment in a bell furnace at a temperature of 600°C and a holding time of 10 hours. After aging treatment, the C19400 alloy fully precipitates the second phase, which greatly improves the strength of the material while also having suitable electrical conductivity.

[0051] The eighth step is pickling: remove the surface oxide scale and passivate the copper strip. Use 20% dilute sulfuric acid to clean the surface oxide scale of the copper strip; use a passivation solution with a concentration of 6‰ to passivate the surface of the copper strip. The passivation working temperature is maintained at 80°C, and the passivation solution is benzotriazole.

[0052] The ninth step is finished product rolling: the thickness of the final rolled product is 0.2mm. To ensure product performance, the finished product processing rate is 40%. The residual stress value of the obtained product is between 80 and 90MPa, the tensile strength of the obtained product is between 430 and 440MPa, and the conductivity of the obtained product is between 60 and 65%IACS.

[0053] The tenth step, cleaning: degrease and passivate the surface of the finished copper strip, use a 5% degreaser to clean the surface grease, use a 6‰ passivation liquid to passivate the surface, the passivation working temperature is maintained at 80°C, and the passivation liquid is benzotriazole.

[0054] Step 11, vibration aging: Use fixtures and connecting wires to connect the wound strip to the vibration aging equipment, select 150HZ for the excitation frequency, 20KN for the excitation force, and 60 minutes for the aging time. The residual stress value of the obtained product is between 40 and 49MPa, the tensile strength of the obtained product is between 430 and 440MPa, and the conductivity of the obtained product is between 60 and 65%IACS. Compared with the finished strip after finished rolling, after vibration aging, the residual stress of the final product is greatly reduced, and the residual stress of the strip is eliminated by 50%, while the tensile strength and conductivity do not change.

[0055] Step 12, performance testing and finished product cutting: sampling for performance testing. The material performance indicators meet the user's requirements. After that, the finished copper strip is cut and the strip is cut into 50mm width. The strip width tolerance, roll weight, etc. are implemented according to the contract requirements. After passing the inspection, it is packaged and stored.

[0056] In this embodiment, a vibration aging process for ingots and a vibration aging process for finished strips are added to the process route. After the vibration aging treatment of the ingots, the casting residual stress can be eliminated by 60%, so that the shape of the hot-rolled strip coil is improved while meeting the tensile strength and electrical conductivity requirements after hot rolling; after the vibration aging treatment of the finished strip, the tensile strength and electrical conductivity of the material remain unchanged, and the residual stress of the copper strip can be eliminated by 50%, thereby improving the stamping and etching applicability of the material.

[0057] Example 3: In this example, a C19400 ingot is first produced, with a weight of 10 tons, a hot-rolled thickness of 16 mm, and a state of R. The hot-rolled coil is required to have a tensile strength of more than 280 MPa, a conductivity of more than 20% IACS, no cracks after hot rolling, and qualified quality.

[0058] Then, after the hot-rolled coil is cold-processed, the C19400 strip produced has a specification of 0.2×50mm. The final product has a tensile strength between 430 and 440MPa, a conductivity of 60 to 65%IACS, and a residual stress of less than 60MPa.

[0059] The C19400 strip prepared in this embodiment uses the copper strip preparation process capable of eliminating processing residual stress described in the present invention, and its process flow includes: smelting, semi-continuous casting, heating, hot rolling, strip coil milling, initial rolling, trimming, annealing, pickling, finished product rolling, cleaning, vibration aging, performance testing, shearing and warehousing.

[0060] The specific steps are as follows: Step 1: Melting and Casting Weigh and place the configured standard cathode copper, old materials of this brand, small metals, etc. into a 10 t melting furnace for non-vacuum melting, and cover them with a mixture of graphite powder and dehydrated charcoal with a thickness of not less than 200 mm. The melting furnace uses electric heating to melt into a molten liquid at 1300°C. In order to ensure the quality of the molten liquid, the raw materials and covering agents used must be dry and oil-free; After melting, the melt is placed in a holding furnace for static standing, which is conducive to the slag of oxides and carbides in the melt to float up. The floating slag is removed to purify the melt. The melt after static standing and slag removal is sampled and analyzed, and the composition is adjusted to ensure that the melt composition is qualified. The main components of the melt are: Cu content 97.21%, Fe content 2.5%, P content 0.135%, Zn content 0.15%, Pb content 0.005%; Semi-continuous casting is adopted, and borax, carbon black, or protective gas is used to cover the melt in the crystallizer during casting; casting speed is 12m / h; cooling water flow rate: 900 L / min; The width of the cast ingot is 600mm and the thickness is 260mm. This width-to-thickness ratio is conducive to the stable casting of the ingot and the floating of the slag. When the ingot length required by the strip is reached, the casting is stopped. After sawing, a C19400 ingot weighing 10 tons was obtained; the residual stress of the ingot was between 18 and 22 MPa.

[0061] The second step is vibration aging The main process parameters involved in vibration aging are: excitation frequency, excitation force, and aging time. When performing vibration aging on C19400 ingots, the excitation frequency is selected as 10HZ, the excitation force is 5KN, and after aging for 10 minutes, the casting residual stress of the C19400 ingot is between 12 and 15MPa, and the casting residual stress is reduced by about 30%, and the stress value is improved.

[0062] The third step is heating and hot rolling The ingot is heated by a walking-beam heating furnace at a heating temperature of 950°C and homogenized for 6 hours; it is then taken out of the furnace for hot rolling, with a final thickness of 16.0 mm, a total processing rate of 92.6% for the hot-rolled strip, 11 rolling passes, a final hot rolling temperature of 700°C, and an online solution process in the last pass.

[0063] After hot rolling, the tensile strength of the coil is 295MPa, the conductivity is 26%IACS, there is no edge crack on the surface of the coil, the quality is qualified, the lateral tolerance of the coil is within 0.055mm, and the dimensional accuracy is good; the plate shape of the coil is between 98 and 108I, and the plate shape is good.

[0064] The fourth step is milling: the hot-rolled strip is milled on the double-sided milling machine. The milling cutter speed is 900r / min, the milling speed is 20m / min, and there is no missed milling, no oxidation pits, and no sticky chips on the surface.

[0065] The fifth step is the initial rolling: the hot rolled strip coil after milling is subjected to the initial rolling on a four-roll initial rolling mill. The rolling process is 10 times with an average rolling speed of 350 m / min. Emulsion lubrication is used during the rolling process.

[0066] During the rolling process, controlling the last pass processing rate to 6% and the rolling coiling tension to 40KN is one of the effective means to control the strip thickness tolerance and rolled plate shape.

[0067] Step 6, trimming: trim the edges of the rolled strip on the shearing equipment to remove burrs and rough edges. The trimming width is 40mm and the trimming speed is 250m / min. The uncoiling and coiling tension is adjusted by a loop method to avoid surface scratches caused by excessive changes in front and back tension.

[0068] The seventh step is bell annealing: the copper strip is subjected to aging annealing treatment in a bell furnace at a temperature of 600°C and a holding time of 10 hours. After aging treatment, the C19400 alloy fully precipitates the second phase, which greatly improves the strength of the material while also having suitable electrical conductivity.

[0069] The eighth step is pickling: remove the surface oxide scale and passivate the copper strip. Use 20% dilute sulfuric acid to clean the surface oxide scale of the copper strip; use a passivation solution with a concentration of 6‰ to passivate the surface of the copper strip. The passivation working temperature is maintained at 80°C, and the passivation solution is benzotriazole.

[0070] The ninth step is finished product rolling: the thickness of the final rolled product is 0.2mm. To ensure product performance, the finished product processing rate is 40%. The residual stress value of the obtained product is between 80 and 90MPa, the tensile strength of the obtained product is between 430 and 440MPa, and the conductivity of the obtained product is between 60 and 65%IACS.

[0071] The tenth step, cleaning: degrease and passivate the surface of the finished copper strip, use a 5% degreaser to clean the surface grease, use a 6‰ passivation liquid to passivate the surface, the passivation working temperature is maintained at 80°C, and the passivation liquid is benzotriazole.

[0072] The eleventh step, vibration aging: use the fixture and connecting wire to connect the wound strip to the vibration aging equipment, select the excitation frequency of 10HZ, the excitation force of 5KN, and the aging time of 10 minutes. The residual stress value of the obtained product is between 48 and 53MPa, the tensile strength of the obtained product is between 430 and 440MPa, and the conductivity of the obtained product is between 60 and 65%IACS. Compared with the finished strip after finished rolling, the residual stress of the final product is greatly reduced after vibration aging, and the residual stress of the strip is eliminated by 40%, while the tensile strength and conductivity do not change.

[0073] Step 12, performance testing and finished product cutting: sampling for performance testing. The material performance indicators meet the user's requirements. After that, the finished copper strip is cut and the strip is cut into 50mm width. The strip width tolerance, roll weight, etc. are implemented according to the contract requirements. After passing the inspection, it is packaged and stored.

[0074] In this embodiment, a vibration aging process for ingots and a vibration aging process for finished strips are added to the process route. After the vibration aging treatment of the ingots, the casting residual stress can be eliminated by 30%, so that the shape of the hot-rolled strip coil is improved while meeting the tensile strength and electrical conductivity requirements after hot rolling; after the vibration aging treatment of the finished strip, the tensile strength and electrical conductivity of the material remain unchanged, and the residual stress of the copper strip can be eliminated by 40%, thereby improving the stamping and etching applicability of the material.

[0075] Analysis of Examples 1-3: In Example 1, the technical parameters used for vibration aging of ingots are: the excitation frequency is 90HZ, the excitation force is 12KN, and the aging time is 25 minutes; the technical parameters used for vibration aging of rolled strips are: the excitation frequency is 80HZ, the excitation force is 10KN, and the aging time is 20 minutes.

[0076] It can be seen from the specific embodiments that after adding vibration aging to the ingot, the casting stress reduction value reaches 60%, the hot rolling quality is improved after homogenization annealing of the ingot, the rolled plate shape value is between 90 and 100I, and the plate shape is good; after multiple processing steps, after adding vibration aging to the rolled strip, the residual stress of the final finished strip is eliminated by 50%, the residual stress improvement effect is obvious, and the strength and conductivity of the product will not be reduced, the stamping and etching forming properties of the material are improved, and the purpose of better eliminating residual stress is achieved. In Example 2, the technical parameters used for the vibration aging of the ingot are: the excitation frequency is 150HZ, the excitation force is 20KN, and the aging time is 60 minutes, so that the casting stress reduction value is 60%; the technical parameters used for the vibration aging of the rolled strip are: the excitation frequency is 150HZ, the excitation force is 20KN, and the aging time is 60 minutes, so that the residual stress reduction value of the finished strip is 50%, which is consistent with the effect obtained in Example 1, but considering the operation time, etc., Example 1 is more suitable.

[0077] In Example 3, the technical parameters used for the vibration aging of the ingot are: the excitation frequency is 10 Hz, the excitation force is 5 KN, and the aging time is 10 minutes, so that the casting stress reduction value is more than 30%; the technical parameters used for the vibration aging of the rolled strip are: the excitation frequency is 10 Hz, the excitation force is 5 KN, and the aging time is 10 minutes, so that the residual stress of the finished strip is reduced by more than 40%, and the residual stress is significantly reduced, which can meet the needs of subsequent continuous stamping and etching forming.

[0078] Example 4: Based on Example 1, in addition to the process parameters of two vibration aging treatments, the process parameters of other treatments are as follows: (1) In the first step, the melt temperature is 1100°C; the casting speed of the semi-continuous casting is 2 m / h, and the cooling water flow rate is 100 L / min; (2) In the third step, the heating temperature in hot rolling is 800°C, the homogenization annealing time is 9 hours, the hot rolling strip processing rate is 97%, the rolling passes are 7, and the hot rolling final rolling temperature is 750°C; (3) In the fourth step, the milling speed is 8 m / min and the milling amount is 1.0 mm / face; (4) In the fifth step, the number of rolling passes for the initial rolling of the slab is 7; (5) In the seventh step, the aging annealing temperature is 400°C and the holding time is 3 hours; (6) In the eighth step, the concentration of dilute sulfuric acid used for pickling is 5%, and the concentration of benzotriazole passivation solution is 3‰; (7) In the tenth step, the concentration of the degreasing agent used for degreasing cleaning is 0.5%, and the concentration of the benzotriazole passivation solution is 3‰.

[0079] The residual stress of the final finished strip is 40~46Mpa, the tensile strength is 430~440Mpa, and the conductivity is 60~65%IACS, which can meet the forming and processing needs of connectors, lead frames, structural parts and other products.

[0080] Example 5: Based on Example 1, in addition to the process parameters of two vibration aging treatments, the process parameters of other treatments are as follows: (1) In the first step, the melt temperature is 1200°C; the casting speed of the semi-continuous casting is 8 m / h, and the cooling water flow rate is 600 L / min; (2) In the third step, the heating temperature in hot rolling is 900°C, the homogenization annealing time is 4 hours, the hot rolling strip processing rate is 90%, the rolling passes are 13, and the hot rolling final rolling temperature is 650°C; (3) In the fourth step, the milling speed is 15 m / min and the milling amount is 0.2 mm / face; (4) In the fifth step, the number of rolling passes for the slab initial rolling is 12 times; (5) In the seventh step, the aging annealing temperature is 500°C and the holding time is 7 hours; (6) In the eighth step, the concentration of dilute sulfuric acid used for pickling is 10%, and the concentration of benzotriazole passivation solution is 4‰; (7) In the tenth step, the concentration of the degreasing agent used for degreasing cleaning is 3%, and the concentration of the benzotriazole passivation solution is 5‰.

[0081] The residual stress of the final finished strip is 43~48Mpa, the tensile strength is 430~440Mpa, and the conductivity is 60~65%IACS, which can meet the forming and processing needs of connectors, lead frames, structural parts and other products.

[0082] The effect and importance of vibration aging in the present invention are illustrated by several comparative examples.

[0083] Comparative Example 1: This comparative example is different from Example 1 in that: no vibration aging treatment is performed on the ingots and finished strips during the preparation process, and other process parameters are the same.

[0084] During the preparation process, the tensile strength of the coil after hot rolling of the ingot is 296MPa, the conductivity is 25.5%IACS, the surface quality after rolling is qualified, the lateral tolerance of the coil is within 0.06mm, and the dimensional accuracy is general; the coil plate shape is 105-118I, the plate shape is worse than that of Example 1, and the residual stress of the ingot is 18-22Mpa, which has not decreased. Although the tensile strength of the prepared copper alloy C19400 strip is 430-440Mpa, and the conductivity of the product is 60-65%IACS, the final residual stress value of the product is 80-90MPa, and there is no sign of elimination. The residual stress of the strip is large, which is not conducive to subsequent stamping and etching.

[0085] Comparative Example 2: Compared with Example 1, this comparative example differs in that the finished strip after rolling is not subjected to vibration aging treatment, and other process parameters are the same.

[0086] In this comparative example, before hot rolling, a vibration aging process is added to the ingot, and the residual stress of the ingot is 7.2-9.8Mpa, the residual stress is eliminated by 60%, and the lateral tolerance is 0.05mm. The strip shape after hot rolling is 90-100I, and the plate shape is good. However, after the finished product is rolled, the vibration aging process of the finished strip described in the present invention is not performed, so that the residual stress value of the final finished strip is between 70-80MPa, and the residual stress of the strip is only reduced by 11%-12.5%. Although the tensile strength of the obtained product is between 430-440MPa, and the product conductivity is between 60-65%IACS, which meets the use requirements, the residual stress of the final product is still large, which is not conducive to subsequent stamping and etching.

[0087] Comparative Example 3: This comparative example is different from Example 1 in that the ingot is not subjected to vibration aging treatment before hot rolling, and other process parameters are the same.

[0088] In this comparative example, the ingot was not subjected to vibration aging treatment before hot rolling, so the residual stress of the ingot was 18-22Mpa, which did not decrease; the transverse tolerance of the coil after hot rolling was within 0.06mm, the dimensional accuracy was general, the coil shape was 105-118I, and the shape was worse than that of Example 1. After the finished product was rolled, the vibration aging treatment was carried out, and the final residual stress value of the prepared C19400 strip was between 55 and 63MPa, the residual stress elimination value was more than 30%, the tensile strength of the obtained product was between 430 and 440MPa, and the conductivity of the obtained product was 60-65%IACS, and the strength and conductivity of the strip were not reduced. After vibration aging, the residual stress of the finished strip was improved, but the improvement effect was limited, and the residual stress was still large, which was not conducive to subsequent stamping and etching.

[0089] It can be seen from Comparative Examples 1-3 that vibration aging treatment of the ingot before hot rolling and vibration aging treatment of the strip after finished rolling are indispensable. Even if aging treatment is performed separately, the residual stress in the final strip product is difficult to reach the ideal value, and it is difficult to meet the needs of subsequent continuous stamping and etching.

[0090] Comparative Example 4: Compared with Example 1, the difference between this comparative example and Example 1 is that: (1) the technical parameters used for vibration aging of the ingot are: the excitation frequency is selected as 180HZ, the excitation force is 30KN, the aging time is 80 minutes, and the casting stress of the ingot after vibration aging is 25MPa, and the casting stress begins to increase.

[0091] (2) The technical parameters used for vibration aging of rolled strip are: the excitation frequency is 170HZ, the excitation force is 25KN, the aging time is 70 minutes, and the residual stress of the finished strip is 95MPa. The residual stress tends to increase, and the effect of eliminating the residual stress is not achieved.

[0092] When the excitation frequency and excitation force used in vibration aging treatment are too large, the resonance will be too strong or the amplitude will be too large, which will cause the defects inside the material (such as cracks, shrinkage, etc.) to tend to expand. If the vibration time is too long, this situation will be aggravated. Therefore, the residual stress of the material will increase after treatment.

[0093] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Those skilled in the art should understand that the specific implementation modes of the present invention may be modified or replaced by equivalents with reference to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the pending claims.

Claims

1. A copper strip preparation process capable of eliminating processing residual stress, characterized in that: Two vibration aging treatments are carried out during the preparation process, the first is the vibration aging treatment of the ingot before hot rolling of the ingot, and the second is the vibration aging treatment of the finished strip after the finished product is rolled; The process parameters of the ingot vibration aging treatment are: excitation frequency of 10-150 Hz, excitation force ≤ 20 KN, aging time ≤ 60 minutes; The process parameters of the vibration aging treatment of the finished strip are: the excitation frequency is 10-150 Hz, the excitation force is ≤20 KN, and the aging time is ≤60 minutes.

2. The copper strip preparation process according to claim 1, characterized in that: The process parameters of the ingot vibration aging treatment are: excitation frequency of 90 Hz, excitation force of 12 KN, and aging time of 25 minutes; the process parameters of the finished strip aging treatment are: excitation frequency of 80 Hz, excitation force of 10 KN, and aging time of 20 minutes.

3. The copper strip preparation process according to claim 1, characterized in that: The process parameters of the ingot vibration aging treatment are: excitation frequency of 150 Hz, excitation force of 20 KN, and aging time of 60 minutes; the process parameters of the finished strip aging treatment are: excitation frequency of 150 Hz, excitation force of 20 KN, and aging time of 60 minutes.

4. The copper strip preparation process according to claim 1, characterized in that: The process parameters of the ingot vibration aging treatment are: excitation frequency of 10 Hz, excitation force of 5 KN, and aging time of 10 minutes; the process parameters of the finished strip aging treatment are: excitation frequency of 10 Hz, excitation force of 5 KN, and aging time of 10 minutes.

5. A copper strip preparation process capable of eliminating processing residual stress, characterized in that: The method comprises the following steps: first, melting the prepared raw materials, the melt temperature is 1100-1300°C; semi-continuous casting is adopted, borax, carbon black or protective gas is used to cover the melt in the crystallizer, the casting speed is 2-12 m / h; the cooling water flow rate is 100-1000 L / min; The second step is to perform vibration aging treatment on the ingot, using the process parameters for vibration aging treatment on the ingot in the process for preparing copper and copper alloy strips as described in any one of claims 1 to 4; The third step is to heat the ingot after the previous step, the heating temperature is 800-980°C, and the homogenization annealing time is 4-9 hours; the hot rolling is carried out, the total processing rate of the hot-rolled strip is 90%-97%, the total number of passes is 7-13, the hot rolling final rolling temperature is 650-750°C, and the last pass is online solid solution; The fourth step is to perform strip milling and edge milling on the hot-rolled strip coil on a double-sided milling machine, with a milling speed of 8 to 20 m / min and a milling amount of 0.2 to 1.0 mm / face; The fifth step is to perform blank rolling on the milled hot-rolled coil on the rolling mill, with 7 to 12 rolling passes and an average rolling speed of 350 m / min. Step 6: Shear the edges of the rolled strip on a shearing device; The seventh step is to perform aging annealing on the copper strip after edge trimming, the annealing temperature is 400-600°C, and the insulation time is 3-10 hours; The eighth step is to remove the surface oxide scale and passivate the copper strip. Use dilute sulfuric acid to clean the surface oxide scale of the copper strip; use passivation liquid to passivate the surface of the copper strip, and keep the passivation working temperature at 60-80°C; The ninth step is to carry out finished product rolling in a finishing mill at a rolling speed of 80 to 600 m / min; The tenth step is to degrease and passivate the surface of the finished copper strip, use a degreasing agent to clean the surface grease, use a passivation liquid to passivate the surface, and keep the passivation working temperature at 50-80°C; Step 11: vibratory aging treatment of the finished strip, using the process parameters of vibratory aging treatment of the finished strip in the process for preparing copper and copper alloy strips according to any one of claims 1 to 4; The twelfth step is to take samples for performance testing. After passing the test, the finished copper and copper alloy strips are cut, packaged and stored.

6. The copper strip preparation process according to claim 5, characterized in that: In the fifth step of slab rolling, the processing rate of the last pass is controlled to be 6%, and the rolling coiling tension is 40KN.

7. The copper strip preparation process according to claim 5, characterized in that: In the eighth step, the concentration of dilute sulfuric acid is 5% to 20%, the passivation solution is benzotriazole, and the concentration of the passivation solution is 3 to 6‰.

8. The copper strip preparation process according to claim 5, characterized in that: In the tenth step, the concentration of the degreasing agent is 0.5-5%, the passivation solution is benzotriazole, and the concentration of the passivation solution is 3-6‰.

9. A copper strip, characterized in that: The copper strip is prepared by the copper strip preparation process as described in any one of claims 1 to 8.