Small-diameter beryllium copper microwire for aviation electric connector and preparation method of small-diameter beryllium copper microwire

Abstract

The invention discloses a small-diameter beryllium copper microwire for an aviation electric connector and a preparation method of the small-diameter beryllium copper microwire, and belongs to the technical field of beryllium copper alloy. The small-diameter beryllium copper microwire is manufactured through the working procedures of homogenizing annealing, extrusion, hot rolling, annealing, primary acid pickling, stretching, secondary acid pickling, bright continuous solid solution, multi-mode stretching and the like, an oxidation film on the surface of the beryllium copper microwire is eliminated through the acid pickling and bright continuous solid solution working procedures, and the surface quality of the beryllium copper microwire is remarkably improved; the beryllium copper microwire subjected to finished product stretching is bright in surface, free of cracks, scratches and other surface defects and stable in mechanical property, the hard tensile strength of the beryllium copper microwire can reach 1100 MPa or above, and the product consistency is good.

Description

Technical Field

[0001] The invention belongs to the technical field of beryllium copper alloys, and in particular relates to a thin-diameter beryllium copper microwire for an aviation electrical connector and a preparation method thereof. Background Art

[0002] As core components for power and signal transmission in aircraft, aviation electrical connectors' reliability, lightweight design, and resistance to extreme environments are directly linked to the overall performance of aviation equipment. With the rapid development of avionics systems toward miniaturization, higher frequencies, and higher densities, traditional copper alloys, due to their insufficient strength and poor fatigue resistance, struggle to meet the stringent requirements of the next generation of electrical connectors for miniature contacts and high-precision conductors. In this context, beryllium copper alloy, with its high strength, high elastic modulus, and excellent conductivity, has become the preferred material for microwires in aviation electrical connectors.

[0003] Beryllium copper microwires experience work hardening during conventional multi-pass drawing. Further drawing can affect the surface quality of the microwires, resulting in defects such as ripples and wrinkles. To eliminate work hardening, the beryllium copper microwires must be annealed in conjunction with a heat treatment process. However, during high-temperature annealing, an oxide film forms on the surface of the beryllium copper microwires, which can lead to defects such as wire breakage and surface scratches during subsequent drawing, affecting the surface quality and dimensional tolerances of the beryllium copper microwire products.

[0004] Therefore, developing a method for preparing beryllium copper microwires with bright surface and high dimensional accuracy has become an urgent need in the field of aviation precision manufacturing. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a thin-diameter beryllium copper microwire for aviation electrical connectors and a preparation method thereof. The thin-diameter beryllium copper microwire obtained by the method of the present invention has a bright surface and no cracks, and can be mass-produced.

[0006] A first aspect of the present invention provides a method for preparing a thin-diameter beryllium copper microwire for an aviation electrical connector, the method comprising:

[0007] Step S1, heat the beryllium copper alloy ingot at 760-810° C. for 4-7 hours and then extrude it to obtain a rod blank;

[0008] Step S2, hot rolling the billet at 720-760° C. for 80-120 min, and annealing the billet at 740-780° C. for 30-60 min.

[0009] Step S3, soaking the annealed rod in a first pickling solution at a temperature of not less than 80°C for 3-5 hours, rinsing it, and then soaking it in a second pickling solution at room temperature for 0.5-3 minutes, rinsing it again, and then drying it;

[0010] Step S4, repeatedly drawing and quenching the dried rod blank to obtain a wire blank;

[0011] The quenching temperature is 740-780°C and the holding time is 25-45 minutes;

[0012] Step S5, soaking the wire billet in a first pickling solution at a temperature of not less than 80° C. for 3-5 hours, rinsing it, and then soaking it in a second pickling solution at room temperature for 0.5-3 minutes, rinsing it again, and then drying it;

[0013] Step S6, sequentially subjecting the dried wire blank to a first multi-mode stretching and a first solution treatment;

[0014] The first solution treatment is carried out under nitrogen protection at a temperature of 760-810°C and a wire billet running speed of 20-25m / min;

[0015] Step S7, sequentially subjecting the wire blank that has undergone the first solution treatment to a second multi-mode stretching and a second solution treatment;

[0016] The second solution treatment is carried out under nitrogen protection at a temperature of 720-760°C and a wire billet running speed of 20-25m / min;

[0017] Step S8, the wire blank that has undergone the second solid solution treatment is stretched to obtain a fine-diameter beryllium copper microwire.

[0018] According to the preparation method described in the first aspect of the present invention, in step S3 and step S5, the first pickling solution is composed of sulfuric acid and water in a volume ratio of (7-8):10; the second pickling solution is composed of nitric acid and water in a volume ratio of (5-7):10.

[0019] According to the preparation method described in the first aspect of the present invention, in step S3 and step S5, warm water with a temperature of 30-40° C. is used to rinse the rod blank and the wire blank.

[0020] According to the preparation method described in the first aspect of the present invention, in step S1, the preparation process of the beryllium copper alloy ingot is as follows:

[0021] Weighing baked raw materials according to the chemical composition and mass percentage of the beryllium copper alloy ingot; the raw materials include: beryllium copper master alloy with a beryllium content of 3.4-10% by mass, electrolytic copper, electrolytic nickel and electrolytic cobalt;

[0022] The weighed raw materials are placed in a vacuum induction melting furnace for melting at a temperature of 1250-1350°C for 100-150 minutes. The raw materials are stirred 6-10 times during the melting process.

[0023] The molten alloy is cast into a crystallizer through multi-stage filtration to obtain a beryllium copper alloy ingot by semi-continuous casting.

[0024] According to the preparation method of the first aspect of the present application, in the step S1, the speed of extrusion is 15-20 m / min, and the extrusion ratio is 10-20.

[0025] According to the preparation method of the first aspect of the present application, in the step S2, the speed of hot rolling is 40-50 m / min, the total processing rate is 90-96%, and the pass processing rate is 6-14%.

[0026] According to the preparation method of the first aspect of the present application, in the step S4, the drawing speed of the repeated drawing is 20-25 m / min, the total processing rate is 90-94%, and the pass processing rate is 19-25%.

[0027] According to the preparation method of the first aspect of the present application, in the step S6, the drawing speed of the first multi-mode drawing is 40-60 m / min, and the total processing rate is 92-97%.

[0028] According to the preparation method of the first aspect of the present application, in the step S7, the drawing speed of the second multi-mode drawing is 60-80 m / min, and the total processing rate is 92-97%.

[0029] According to the preparation method of the first aspect of the present application, in the step S8, the drawing speed of the finished product is 40-60 m / min, and the total processing rate is 29-61%.

[0030] The second aspect of the present application provides a fine-diameter beryllium copper micro-wire for an aviation electrical connector, which is prepared by the preparation method described above.

[0031] The scheme provided by the present application has the following technical effects:

[0032] The fine-diameter beryllium copper micro-wire is prepared by the processes of homogenizing annealing, extrusion, hot rolling, annealing, first pickling, drawing, second pickling, bright continuous solid solution, and multi-mode drawing. The pickling and bright continuous solid solution processes eliminate the oxide film on the surface of the beryllium copper micro-wire, significantly improve the surface quality of the beryllium copper micro-wire, and the beryllium copper micro-wire after finished product drawing has a bright surface without surface defects such as cracks and scratches, and stable mechanical properties, and the hard-state tensile strength can reach more than 1100 MPa, and the product has good consistency.

[0033] In addition, the fine-diameter beryllium copper micro-wire prepared by the present application can be applied to the core components of electrical connectors in the fields of aerospace and electronic information, and has good application prospects. DETAILED DESCRIPTION

[0034] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0035] The first aspect of the present embodiment provides a preparation method of a fine-diameter beryllium copper micro-wire for an aviation electrical connector, and the preparation method comprises the following steps:

[0036] In step S1, the beryllium copper alloy ingot is kept at 760-810℃ for 4-7h and then extruded to obtain a rod blank.

[0037] In step S2, the rod blank is kept at 720-760℃ for 80-120min and then hot-rolled, and the hot-rolled rod blank is annealed at an annealing temperature of 740-780℃ for 30-60min.

[0038] In step S3, the annealed rod blank is soaked in a first acid pickling solution at a temperature not lower than 80℃ for 3-5h to loosen the oxide film on the surface of the rod blank, washed clean, soaked in a second acid pickling solution at room temperature for 0.5-3min to perform bright treatment on the surface of the rod blank, washed clean again, and then dried.

[0039] In step S4, the dried rod blank is subjected to repeated drawing and quenching in sequence to obtain a wire blank; the quenching temperature is 740-780℃, and the holding time is 25-45min.

[0040] In step S5, the wire blank is soaked in a first acid pickling solution at a temperature not lower than 80℃ for 3-5h to loosen the oxide film on the surface of the wire blank, washed clean, soaked in a second acid pickling solution at room temperature for 0.5-3min to perform bright treatment on the surface of the wire blank, washed clean again, and then dried.

[0041] In step S6, the dried wire blank is subjected to first multi-mode drawing and first solid solution treatment in sequence; the first solid solution treatment is performed under nitrogen protection at a temperature of 760-810℃ and a wire blank running speed of 20-25m / min.

[0042] In step S7, the wire blank subjected to the first solid solution treatment is subjected to second multi-mode drawing and second solid solution treatment in sequence; the second solid solution treatment is performed under nitrogen protection at a temperature of 720-760℃ and a wire blank running speed of 20-25m / min.

[0043] In step S8, the wire blank subjected to the second solid solution treatment is subjected to finished product drawing to obtain a fine-diameter beryllium copper micro-wire.

[0044] In this embodiment, the rod blank is first pickled with different pickling solutions to remove the oxide film formed on the surface of the rod blank during the homogenization treatment, extrusion, hot rolling and annealing treatments. The wire blank is then drawn and quenched to produce a wire blank. The wire blank is pickled again with different pickling solutions to remove the oxide film formed on the surface of the wire blank during the drawing and quenching treatments. The wire blank is then multi-mode stretched. In order to avoid the re-generation of the oxide film on the surface of the wire blank during the subsequent heat treatment, this embodiment uses a bright continuous quenching furnace to perform a first solid solution treatment under the protection of high-purity nitrogen. After stretching again, the bright continuous quenching furnace is continued to be used for a second solid solution treatment under the protection of high-purity nitrogen to relieve work hardening. Finally, the finished product is stretched to obtain a fine-diameter beryllium copper microwire.

[0045] In some embodiments, in step S3 and step S5, the first pickling solution is composed of sulfuric acid and water in a volume ratio of (7-8):10; the second pickling solution is composed of nitric acid and water in a volume ratio of (5-7):10.

[0046] The sulfuric acid and nitric acid in this embodiment are of commercially available specifications.

[0047] In this embodiment, the first pickling solution is used to loosen the oxide film on the surface of the rod and wire billets, making it easier to rinse away. Therefore, a mixture of sulfuric acid and water in a volume ratio of (7-8):10 is used, and the soaking time is relatively long to fully loosen the oxide film on the surface of the rod and wire billets. The second pickling solution is used only to brighten the surface of the rod and wire billets. Therefore, a mixture of nitric acid and water in a volume ratio of (5-7):10 is used, and a longer soaking time of 0.5-3 minutes is sufficient.

[0048] The applicant has found through a large number of experiments that when the concentration of sulfuric acid and / or nitric acid in the pickling solution is too high, pits are easily generated on the surface of the rod and wire billets; when the concentration of sulfuric acid and / or nitric acid in the pickling solution is too low, the oxide film removal effect is too poor.

[0049] In some embodiments, in step S3 and step S5, the rod and wire blanks are rinsed with warm water at a temperature of 30-40°C.

[0050] The applicant has found through extensive testing that the surface oxide film cannot be completely removed by washing rod and wire billets with water at a temperature other than 30-40°C.

[0051] In some embodiments, in step S1, the beryllium copper alloy ingot is prepared as follows:

[0052] The baked raw materials are weighed according to the chemical composition and mass percentage of the beryllium copper alloy ingot; the raw materials include: beryllium copper master alloy with beryllium content of 3.4-10%, electrolytic copper, electrolytic nickel and electrolytic cobalt.

[0053] The beryllium copper alloy ingot is C17200 beryllium copper alloy, and the chemical composition and mass percentage are as follows: beryllium: 1.8-2.1wt%; nickel+ cobalt: 0.2-0.5wt%; nickel+ cobalt+ iron: <0.6wt%; total content of trace impurity elements iron, aluminum, silicon, lead: <0.5wt%, and the balance is copper.

[0054] Preferably, the baking temperature of the raw material is 350℃, and the time is 2-6h, so as to remove the gas impurities in the raw material.

[0055] The weighed raw material is placed in a vacuum induction melting furnace for melting, the melting temperature is 1250-1350℃, the melting time is 100-150min, and the melting process is stirred, and the stirring frequency is 6-10 times.

[0056] The alloy liquid after melting is cast into a crystallizer through multi-stage filtration for semi-continuous casting to obtain a beryllium copper alloy ingot.

[0057] The material of the filter screen for multi-stage filtration is alumina ceramic.

[0058] In some embodiments, in the step S1, the speed of the extrusion is 15-20m / min, and the extrusion ratio is 10-20.

[0059] Preferably, in the extrusion process, the inner wall lubricating material of the extrusion barrel is a mixture of molybdenum disulfide, hydraulic oil and graphite powder, and the ratio of molybdenum disulfide: hydraulic oil: graphite powder is 1-3: 1: 1.

[0060] In some embodiments, in the step S2, the speed of the hot rolling is 40-50m / min, the total processing rate is 90-96%, and the pass processing rate is 6-14%.

[0061] In some embodiments, in the step S4, the drawing speed of the repeated drawing is 20-25m / min, the total processing rate is 90-94%, and the pass processing rate is 19-25%.

[0062] In some embodiments, in the step S6, the drawing speed of the first multi-mode drawing is 40-60m / min, and the total processing rate is 92-97%.

[0063] In some embodiments, in the step S7, the drawing speed of the second multi-mode drawing is 60-80m / min, and the total processing rate is 92-97%.

[0064] In some embodiments, in the step S8, the drawing speed of the finished product drawing is 40-60m / min, and the total processing rate is 29-61%.

[0065] Preferably, a water-soluble lubricant is used throughout the stretching process.

[0066] The second aspect of the embodiment provides a fine-diameter beryllium copper micro-wire for an aviation electrical connector, which is prepared by the preparation method described above.

[0067] Example 1

[0068] In the first step, beryllium copper master alloy containing 3.4 wt% of beryllium, electrolytic copper, electrolytic nickel and electrolytic cobalt were respectively loaded into a box-type drying oven and baked at 350°C for 6 hours.

[0069] In the second step, the raw materials were weighed according to the chemical composition requirements of the beryllium copper alloy with the alloy grade C17200, and then the weighed raw materials were put into a vacuum induction melting furnace for melting, with the melting temperature being 1250°C, the stirring frequency being 6 times, and the melting time being 100 minutes.

[0070] In the third step, the molten alloy was cast into a crystallizer through multi-stage filtration for semi-continuous casting, so as to obtain a beryllium copper alloy ingot with a diameter of 175 mm.

[0071] In the fourth step, the beryllium copper alloy ingot was heat treated at 760°C for 7 hours, and then extruded at an extrusion ratio of 15 and an extrusion speed of 17 m / min, so as to obtain a beryllium copper alloy rod blank with a diameter of 45 mm.

[0072] In the fifth step, the rod blank was heat treated at 760°C for 120 minutes, and then hot-rolled for 27 passes, with a total hot-rolling reduction of 96%, a pass reduction of 6-14%, and a hot-rolling speed of 40 m / min, so as to obtain a hot-rolled beryllium copper rod with a diameter of 9 mm; then the hot-rolled beryllium copper rod was annealed in a box-type resistance furnace at an annealing temperature of 760°C for an annealing time of 60 minutes.

[0073] In the sixth step, the annealed rod blank was immersed in a No. 1 pickling tank for 5 hours in a pickling solution at a temperature not lower than 80°C to loosen the surface oxide film of the rod blank, and then washed with warm water at 30°C, and then immersed in a No. 2 pickling tank for 1 minute in a pickling solution at room temperature for surface brightening treatment, and then washed with hot water and cold water, and then dried. The pickling solution in the No. 1 pickling tank had a proportion of sulfuric acid to water of 7:10, and the pickling solution in the No. 2 pickling tank had a proportion of nitric acid to water of 5:10.

[0074] In the seventh step, the cleaned beryllium copper rod blank was drawn for 9 passes at a drawing speed of 20 m / min, with a total reduction of 92% and a pass reduction of 19-25%; quenching was performed every 3 passes at a quenching temperature of 740°C for a quenching time of 45 minutes, so as to obtain a beryllium copper wire blank with a diameter of 2.5 mm.

[0075] In the eighth step, the beryllium copper wire blank is cleaned. First, it is put into a No. 1 pickling tank and soaked in a pickling solution at a temperature of not less than 80°C for 3h to loosen the surface oxide film of the blank, then washed with warm water at 30°C, soaked in a pickling solution in a No. 2 pickling tank at room temperature for 2min for surface brightening, washed with hot and cold water and dried. The pickling solution in the No. 1 pickling tank has a proportion of sulfuric acid to water of 7:10, and the pickling solution in the No. 2 pickling tank has a proportion of nitric acid to water of 5:10.

[0076] In the ninth step, the cleaned beryllium copper wire blank is subjected to first multi-mode drawing at a drawing speed of 40m / min and a total processing rate of 96% to obtain a beryllium copper wire blank with a diameter of 0.5mm.

[0077] In the tenth step, the beryllium copper wire blank after the first multi-mode drawing is subjected to first solid solution treatment in a bright continuous quenching furnace under the protection of high-purity nitrogen at a temperature of 780°C and a wire blank running speed of 20m / min.

[0078] In the eleventh step, the beryllium copper wire blank after the first solid solution treatment is subjected to second multi-mode drawing at a drawing speed of 80m / min and a total processing rate of 96.8% to obtain a beryllium copper wire blank with a diameter of 0.089mm.

[0079] In the twelfth step, the beryllium copper wire blank after the second multi-mode drawing is subjected to second solid solution treatment in a bright continuous quenching furnace under the protection of high-purity nitrogen at a temperature of 720°C and a wire blank running speed of 23m / min.

[0080] In the thirteenth step, the beryllium copper wire blank after the second solid solution treatment is subjected to product drawing at a drawing speed of 60m / min and a total processing rate of 29% to obtain a fine-diameter beryllium copper micro-wire with a diameter of 0.075mm.

[0081] The chemical composition detection results of the fine-diameter beryllium copper micro-wire prepared in Example 1 are as follows:

[0082] Be: 1.92wt%; Co: 0.298wt%; Ni: 0.068wt%; Fe: 0.075wt%; Al: 0.072wt%; Si: 0.073wt%; Pb: 0.001wt%; Ni+Co: 0.366wt%; Ni+Co+Fe: 0.441wt%, and the balance is Cu.

[0083] The tensile strength is 1119.5MPa.

[0084] Example 2

[0085] In the first step, beryllium copper master alloy containing 3.8wt% of beryllium, electrolytic copper, electrolytic nickel and electrolytic cobalt and other raw materials are separately put into a box-type drying oven and baked at 350°C for 2h.

[0086] Second step, according to the chemical composition requirements of the alloy grade C17200 beryllium copper, the raw materials are put into the vacuum induction melting furnace for melting, the melting temperature is 1350℃, the stirring frequency is 10 times, and the melting time is 150 min.

[0087] Third step, the molten alloy is cast into the crystallizer through multi-stage filtration for semi-continuous casting to obtain a beryllium copper alloy ingot with a diameter of 175 mm.

[0088] Fourth step, the beryllium copper alloy ingot is heat treated at 810℃ for 4h, then extruded at an extrusion ratio of 20 and an extrusion speed of 20 m / min to obtain a beryllium copper alloy rod blank with a diameter of 39 mm.

[0089] Fifth step, the rod blank is heat treated at 720℃ for 100 min, then hot rolled for 25 passes at a total rolling rate of 92% and a pass rolling rate of 6-14% and a hot rolling speed of 45 m / min to obtain a hot-rolled beryllium copper rod with a diameter of 11 mm, which is then annealed in a box resistance furnace at an annealing temperature of 780℃ for 50 min.

[0090] Sixth step, the annealed rod blank is immersed in a No. 1 pickling tank for 3h in an acid pickling solution at a temperature not lower than 80℃ to loosen the surface oxide film of the rod blank, then washed with warm water at 35℃, immersed again in a No. 2 pickling tank for 0.5 min in a room temperature acid pickling solution for surface brightening, washed with hot and cold water, and dried. The acid pickling solution in the No. 1 pickling tank has a proportion of sulfuric acid to water of 8:10, and the acid pickling solution in the No. 2 pickling tank has a proportion of nitric acid to water of 7:10.

[0091] Seventh step, the cleaned beryllium copper rod blank is drawn for 9 passes at a drawing speed of 22 m / min, a total rolling rate of 94%, and a pass rolling rate of 19-25%, quenched every 3 passes at a quenching temperature of 760℃ for 30 min to obtain a beryllium copper wire blank with a diameter of 2.7 mm.

[0092] Eighth step, the beryllium copper wire blank is cleaned, first immersed in a No. 1 pickling tank for 4h in an acid pickling solution at a temperature not lower than 80℃ to loosen the surface oxide film of the rod blank, then washed with warm water at 35℃, immersed again in a No. 2 pickling tank for 1 min in a room temperature acid pickling solution for surface brightening, washed with hot and cold water, and dried. The acid pickling solution in the No. 1 pickling tank has a proportion of sulfuric acid to water of 8:10, and the acid pickling solution in the No. 2 pickling tank has a proportion of nitric acid to water of 7:10.

[0093] In the ninth step, the cleaned beryllium copper wire billet is subjected to the first multi-mode stretching at a stretching rate of 60 m / min and a total processing rate of 94.2%, thereby obtaining a beryllium copper wire billet with a diameter of 0.65 mm.

[0094] In the tenth step, the beryllium copper wire billet after the first multi-mode stretching is subjected to the first solid solution treatment in a bright continuous quenching furnace under the protection of high-purity nitrogen at a temperature of 810°C and a wire billet running speed of 25m / min.

[0095] In the eleventh step, the beryllium copper wire billet after the first solution treatment is subjected to a second multi-mode stretching at a stretching rate of 70 m / min and a total processing rate of 97%, thereby obtaining a beryllium copper wire billet with a diameter of 0.113 mm.

[0096] In the twelfth step, the beryllium copper wire billet after the second multi-mode stretching is subjected to a second solid solution treatment in a bright continuous quenching furnace under the protection of high-purity nitrogen at a temperature of 760°C and a wire billet running speed of 25m / min.

[0097] In the thirteenth step, the beryllium copper wire billet after the second solution treatment is stretched into finished product at a stretching rate of 50 m / min and a total processing rate of 55.9%, thereby obtaining a fine-diameter beryllium copper microwire with a diameter of 0.075 mm.

[0098] The chemical composition test results of the thin-diameter beryllium copper microwires prepared in Example 2 are as follows:

[0099] Be: 1.92wt%; Co: 0.288wt%; Ni: 0.074wt%; Fe: 0.080wt%; Al: 0.075wt%; Si: 0.077wt%; Pb: 0.001wt%; Ni+Co: 0.362wt%; Ni+Co+Fe: 0.442wt%, the remainder is Cu.

[0100] The tensile strength is: 1121.9MPa.

[0101] Example 3

[0102] In the first step, raw materials such as beryllium-copper master alloy containing 10 wt% beryllium, electrolytic copper, electrolytic nickel and electrolytic cobalt are respectively placed in a box-type drying oven and baked at 350° C. for 4 hours.

[0103] In the second step, the ingredients are prepared according to the chemical composition requirements of the alloy grade C17200 beryllium copper, and then the raw materials are placed in a vacuum induction melting furnace for melting at a melting temperature of 1280°C. The melting process is stirred 8 times and the melting time is 120 minutes.

[0104] In the third step, the smelted alloy liquid is cast into a crystallizer through multi-stage filtration and semi-continuous casting is performed to obtain a beryllium copper alloy ingot with a diameter of 153 mm.

[0105] Fourthly, the beryllium copper alloy ingot is kept at 780°C for 6 hours, and then is extruded at an extrusion ratio of 10 and an extrusion speed of 15 m / min to obtain a beryllium copper alloy rod with a diameter of 48 mm.

[0106] Fifthly, the rod is kept at 740°C for 80 min, and then is hot-rolled in 22 passes at a total hot-rolling rate of 92% and a pass rate of 6-14% and a hot-rolling speed of 50 m / min to obtain a hot-rolled beryllium copper rod with a diameter of 15 mm, which is then annealed in a box resistance furnace at an annealing temperature of 740°C for 30 min.

[0107] Sixthly, the annealed rod is immersed in a No. 1 pickling tank at a temperature of not less than 80°C for 4 h to loosen the surface oxide film of the rod, and then is washed with warm water at 40°C, and then is immersed in a No. 2 pickling tank at room temperature for 3 min for surface brightening treatment, and then is washed with cold and hot water and dried. The pickling solution in the No. 1 pickling tank has a proportion of sulfuric acid to water of 7:10, and the pickling solution in the No. 2 pickling tank has a proportion of nitric acid to water of 6:10.

[0108] Seventhly, the cleaned beryllium copper rod is drawn in 9 passes at a drawing speed of 25 m / min and a total drawing rate of 94% and a pass rate of 19-25%, and is quenched every 3 passes at a quenching temperature of 780°C for 25 min to obtain a beryllium copper wire blank with a diameter of 3.7 mm.

[0109] Eighthly, the beryllium copper wire blank is cleaned, and is first immersed in a No. 1 pickling tank at a temperature of not less than 80°C for 5 h to loosen the surface oxide film of the rod, and then is washed with warm water at 40°C, and then is immersed in a No. 2 pickling tank at room temperature for 2 min for surface brightening treatment, and then is washed with hot and cold water and dried. The pickling solution in the No. 1 pickling tank has a proportion of sulfuric acid to water of 7:10, and the pickling solution in the No. 2 pickling tank has a proportion of nitric acid to water of 6:10.

[0110] Ninthly, the cleaned beryllium copper wire blank is drawn in a first multi-mode drawing at a drawing speed of 50 m / min and a total drawing rate of 97% to obtain a beryllium copper wire blank with a diameter of 0.64 mm.

[0111] Tenthly, the beryllium copper wire blank after the first multi-mode drawing is subjected to a first solid solution treatment in a bright continuous quenching furnace under the protection of high-purity nitrogen at a temperature of 780°C and a wire blank running speed of 20 m / min.

[0112] The beryllium copper wire blank after the first solution treatment is subjected to a second multi-mode drawing at a drawing speed of 80 m / min, and the total processing rate is 96.5%, so as to obtain a beryllium copper wire blank with a diameter of 0.12 mm.

[0113] In the twelfth step, the beryllium copper wire blank after the second multi-mode drawing is subjected to a second solution treatment by a bright continuous quenching furnace under the protection of high-purity nitrogen, the temperature is 740 DEG C, and the wire blank running speed is 24 m / min.

[0114] In the thirteenth step, the beryllium copper wire blank after the second solution treatment is subjected to a finished product drawing at a drawing speed of 40 m / min, and the total processing rate is 61%, so as to obtain a fine-diameter beryllium copper micro-wire with a diameter of 0.075 mm.

[0115] The chemical composition detection result of the fine-diameter beryllium copper micro-wire prepared in the embodiment 3 is as follows:

[0116] Be: 1.90wt%; Co: 0.273wt%; Ni: 0.071wt%; Fe: 0.069wt%; Al: 0.054wt%; Si: 0.073wt%; Pb: 0.001wt%; Ni+Co: 0.344wt%; Ni+Co+Fe: 0.413wt%, and the balance is copper.

[0117] The tensile strength is 1157.4 MPa.

[0118] In summary, the scheme provided in the application has the following technical effects:

[0119] The fine-diameter beryllium copper micro-wire is prepared through the processes of homogenizing annealing, extrusion, hot rolling, annealing, first pickling, drawing, second pickling, bright continuous solution, multi-mode drawing, etc. The pickling and bright continuous solution processes eliminate the oxide film on the surface of the beryllium copper micro-wire, significantly improve the surface quality of the beryllium copper micro-wire, and the beryllium copper micro-wire after the finished product drawing has a bright surface without surface defects such as cracks and scratches, and the mechanical properties are stable, the hard-state tensile strength can reach more than 1100 MPa, and the consistency of the product is good.

[0120] In addition, the fine-diameter beryllium copper micro-wire prepared in the application can be applied to the core components of electrical connectors in the fields of aerospace and electronic information, and has a good application prospect.

[0121] The above embodiments only express several embodiments of the application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, some modifications and improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. A method for preparing thin-diameter beryllium copper microwires for aviation electrical connectors, characterized in that: The preparation method comprises: Step S1, heat the beryllium copper alloy ingot at 760-810° C. for 4-7 hours and then extrude it to obtain a rod blank; Step S2, hot rolling the billet at 720-760° C. for 80-120 min, and annealing the billet at 740-780° C. for 30-60 min. Step S3, soaking the annealed rod in a first pickling solution at a temperature of not less than 80°C for 3-5 hours, rinsing it, and then soaking it in a second pickling solution at room temperature for 0.5-3 minutes, rinsing it again, and then drying it; Step S4, repeatedly drawing and quenching the dried rod blank to obtain a wire blank; The quenching temperature is 740-780°C and the holding time is 25-45 minutes; Step S5, soaking the wire billet in a first pickling solution at a temperature of not less than 80° C. for 3-5 hours, rinsing it, and then soaking it in a second pickling solution at room temperature for 0.5-3 minutes, rinsing it again, and then drying it; Step S6, sequentially subjecting the dried wire blank to a first multi-mode stretching and a first solution treatment; The first solution treatment is carried out under nitrogen protection at a temperature of 760-810°C and a wire billet running speed of 20-25m / min; Step S7, sequentially subjecting the wire blank that has undergone the first solution treatment to a second multi-mode stretching and a second solution treatment; The second solution treatment is carried out under nitrogen protection at a temperature of 720-760°C and a wire billet running speed of 20-25m / min; Step S8, the wire blank that has undergone the second solid solution treatment is stretched to obtain a fine-diameter beryllium copper microwire.

2. The preparation method according to claim 1, characterized in that In step S3 and step S5, the first pickling solution is composed of sulfuric acid and water in a volume ratio of (7-8):10; the second pickling solution is composed of nitric acid and water in a volume ratio of (5-7):

10.

3. The preparation method according to claim 1, characterized in that In the steps S3 and S5, the rod and wire blanks are rinsed with warm water at a temperature of 30-40°C.

4. The preparation method according to claim 1, characterized in that In step S1, the preparation process of the beryllium copper alloy ingot is as follows: Weighing baked raw materials according to the chemical composition and mass percentage of the beryllium copper alloy ingot; the raw materials include: beryllium copper master alloy with a beryllium content of 3.4-10% by mass, electrolytic copper, electrolytic nickel and electrolytic cobalt; The weighed raw materials are placed in a vacuum induction melting furnace for melting at a temperature of 1250-1350°C for 100-150 minutes. The raw materials are stirred 6-10 times during the melting process. The smelted alloy liquid is cast into a crystallizer through multi-stage filtration and semi-continuous casting is performed to obtain a beryllium copper alloy ingot.

5. The preparation method according to claim 1, characterized in that In the step S1, the extrusion speed is 15-20 m / min, and the extrusion ratio is 10-20.

6. The preparation method according to claim 1, characterized in that In step S2, the hot rolling speed is 40-50 m / min, the total processing rate is 90-96%, and the pass processing rate is 6-14%.

7. The preparation method according to claim 1, characterized in that In the step S4, the stretching rate of the repeated drawing is 20-25 m / min, the total processing rate is 90-94%, and the pass processing rate is 19-25%.

8. The preparation method according to claim 1, characterized in that In the step S6, the stretching rate of the first multimode stretching is 40-60 m / min, and the total processing rate is 92-97%.

9. The preparation method according to claim 1, characterized in that In the step S7, the stretching rate of the second multimode stretching is 60-80 m / min, and the total processing rate is 92-97%.

10. The preparation method according to claim 1, characterized in that In the step S8, the stretching rate of the finished product is 40-60 m / min, and the total processing rate is 29-61%.