Stress relaxation resistant low beryllium copper alloy and preparation method thereof

Abstract

The invention provides a stress relaxation resistant low beryllium copper alloy and a preparation method thereof, and belongs to the technical field of alloys. The stress relaxation resistant low beryllium copper alloy is prepared from the following components in percentage by mass: 0.1 to 0.5 percent of Be, 0.1 to 0.5 percent of Co, 0.1 to 0.3 percent of Sn and the balance of Cu. The Sn element and the Co element are added, and a Cottrel air mass can be formed by utilizing Sn atoms and Co atoms to hinder dislocation motion, so that the stress relaxation resistance is improved. The result of the embodiment shows that the stress relaxation rate of the low-beryllium copper alloy is kept at about 10% in the whole test period, the low-beryllium copper alloy has excellent stress relaxation resistance, meanwhile, the tensile strength of the alloy can reach 750-800 MPa, the hardness of the alloy is 240-260 HV, the conductivity of the alloy is 52-55% IACS, and the low-beryllium copper alloy has high strength, high conductivity and excellent stress relaxation resistance.

Description

Technical Field

[0001] The invention relates to the technical field of alloys, and in particular to a stress relaxation resistant low-beryllium copper alloy and a preparation method thereof. Background Art

[0002] Beryllium copper alloy, as a typical precipitation-strengthened copper alloy, has good corrosion resistance, wear resistance, fatigue resistance, low temperature resistance and non-magnetic properties. It also has good impact resistance and does not produce sparks. It is widely used in connector contacts in the fields of aerospace, electronic communications, etc. Beryllium copper alloy can be divided into high beryllium copper alloy (1.8-2.0wt% beryllium content) and low beryllium copper alloy (0.2-0.6wt% beryllium content) according to its beryllium content. High beryllium copper alloy usually exhibits excellent mechanical properties, such as high hardness, high modulus, wear resistance, high strength and fatigue resistance. However, since beryllium is expensive and highly toxic, low beryllium copper alloy has the advantages of low cost and is beneficial to environmental protection, and has attracted much attention from researchers. However, although low beryllium copper alloy has the above advantages and usually has excellent electrical and thermal conductivity, the mechanical properties of low beryllium copper alloy are often low, which limits the application of low beryllium copper alloy.

[0003] Moreover, with the advancement of science and technology, more stringent requirements have been put forward for the performance of low beryllium copper alloys, especially in terms of stress relaxation resistance. Stress relaxation resistance is a key measure to ensure reliable contact between connector contacts, and is one of the key performances of connector contact materials in practical applications. Stress relaxation means that when the strain remains unchanged, the stress of an alloy or material decreases with increasing time. Stress relaxation resistance can be a good indicator of the life of connector contact products. However, the current low beryllium copper alloy is not enough to meet this growing demand.

[0004] Therefore, there is an urgent need to provide a low-beryllium copper alloy having high strength, high conductivity and excellent stress relaxation resistance. Summary of the invention

[0005] The object of the present invention is to provide a stress relaxation resistant low-beryllium copper alloy and a preparation method thereof. The low-beryllium copper alloy provided by the present invention has high strength, excellent electrical conductivity and stress relaxation resistance.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides a stress relaxation resistant low-beryllium copper alloy, which comprises, by mass percentage, 0.1-0.5% Be, 0.1-0.5% Co, 0.1-0.3% Sn and the balance Cu.

[0008] The present invention also provides a method for preparing the stress relaxation resistant low-beryllium copper alloy described in the above technical solution, comprising the following steps:

[0009] (1) smelting raw materials of Cu, Co and Be to obtain a Cu-Be-Co melt; mixing a copper-coated Sn raw material with the Cu-Be-Co melt and smelting the mixture to obtain a Cu-Be-Co-Sn alloy melt;

[0010] (2) casting the Cu—Be—Co—Sn alloy melt obtained in step (1) to obtain a Cu—Be—Co—Sn alloy ingot;

[0011] (3) The Cu-Be-Co-Sn alloy ingot obtained in step (2) is subjected to solution treatment, first cooling, first cold rolling, aging treatment, second cooling and second cold rolling in sequence to obtain a stress relaxation resistant low-beryllium copper alloy.

[0012] Preferably, the smelting temperature in step (1) is 1100-1300°C.

[0013] Preferably, the temperature of the solution treatment in step (3) is 920-950° C., and the time of the solution treatment is 50-60 min.

[0014] Preferably, the first cooling method in step (3) is water cooling.

[0015] Preferably, the second cooling method in step (3) is air cooling.

[0016] Preferably, the total rolling reduction of the first cold rolling treatment in step (3) is 73-75%.

[0017] Preferably, the temperature of the aging treatment in step (3) is 430-450°C.

[0018] Preferably, the aging treatment time in step (3) is 20 minutes to 4 hours.

[0019] Preferably, the total rolling reduction of the second cold rolling process in step (3) is 45-50%.

[0020] The present invention provides a stress relaxation resistant low-beryllium copper alloy, which comprises, by mass percentage, 0.1-0.5% Be, 0.1-0.5% Co, 0.1-0.3% Sn and the balance Cu. The present invention adds Sn and Co elements, and utilizes Sn atoms and Co atoms to form Cottrel gas masses to hinder dislocation movement, thereby improving stress relaxation resistance. The results of the embodiments show that the stress relaxation rate of the low-beryllium copper alloy provided by the present invention is maintained at about 10% during the entire test period, and has excellent stress relaxation resistance. At the same time, the tensile strength of the alloy can reach 750-800MPa, the hardness is 240-260HV, and the conductivity is 52-55%IACS, which has high strength, high conductivity, and excellent stress relaxation resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the treatment of a Cu-Be-Co-Sn alloy ingot according to the present invention;

[0022] Figure 2 The hardness value variation curve of the sample after aging treatment during the process of preparing the stress relaxation resistant low beryllium copper alloy in Examples 1 to 6 of the present invention;

[0023] Figure 3 The conductivity change curve of the sample after aging treatment during the process of preparing the stress relaxation resistant low beryllium copper alloy in Examples 1 to 6 of the present invention;

[0024] Figure 4 The tensile mechanical property curve of the stress relaxation resistant low beryllium copper alloy provided in Example 3 of the present invention;

[0025] Figure 5 This is the stress relaxation resistance performance curve of the stress relaxation resistance low beryllium copper alloy provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0026] The invention provides a stress relaxation resistant low-beryllium copper alloy, which comprises, by mass percentage, 0.1-0.5% of Be, 0.1-0.5% of Co, 0.1-0.3% of Sn and the balance of Cu.

[0027] The stress relaxation resistant low beryllium copper alloy provided by the present invention comprises 0.1-0.5% Be, preferably 0.1-0.3% Be by mass percentage. In an embodiment of the present invention, the mass percentage of Be can be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%. In the present invention, Be can be combined with Cu to increase the strength and hardness of the alloy and improve its corrosion resistance.

[0028] In terms of mass percentage, the stress relaxation resistant low beryllium copper alloy provided by the present invention comprises 0.1-0.5% Co, preferably 0.3-0.5% Co. In an embodiment of the present invention, the mass percentage of Co may be 0.3%, 0.4% or 0.5%.

[0029] The stress relaxation resistant low beryllium copper alloy provided by the present invention comprises Sn 0.1-0.3%, preferably Sn 0.2-0.3%. In an embodiment of the present invention, the mass percentage of Co can be 0.1%, 0.2% or 0.3%. In the present invention, Sn atoms and Co atoms can form Cottrel gas masses to hinder dislocation movement, thereby improving the stress relaxation resistance of the alloy.

[0030] The stress relaxation resistant low beryllium copper alloy provided by the present invention includes a balance of Cu in terms of mass percentage. In the present invention, Cu is used as the base metal of the beryllium copper alloy.

[0031] The invention designs the composition of the low-beryllium copper alloy and controls the contents of the Be element, the Co element and the Sn element in the alloy, thereby improving the stress relaxation resistance of the beryllium copper alloy.

[0032] The present invention also provides a method for preparing the stress relaxation resistant low-beryllium copper alloy described in the above technical solution, comprising the following steps:

[0033] (1) smelting raw materials of Cu, Co and Be to obtain a Cu-Be-Co melt; mixing a copper-coated Sn raw material with the Cu-Be-Co melt and smelting the mixture to obtain a Cu-Be-Co-Sn alloy melt;

[0034] (2) casting the Cu—Be—Co—Sn alloy melt obtained in step (1) to obtain a Cu—Be—Co—Sn alloy ingot;

[0035] (3) The Cu-Be-Co-Sn alloy ingot obtained in step (2) is subjected to solution treatment, first cooling, first cold rolling, aging treatment, second cooling and second cold rolling in sequence to obtain a stress relaxation resistant low-beryllium copper alloy.

[0036] The present invention melts raw materials of Cu, Co and Be to obtain a Cu-Be-Co melt; and mixes a copper-coated Sn raw material with the Cu-Be-Co melt and then melts the mixture to obtain a Cu-Be-Co-Sn alloy melt.

[0037] In the present invention, the raw materials of Cu, Co and Be preferably include pure Cu, pure Co and copper-beryllium master alloy. The present invention has no special limitation on the specific purity of the pure copper, pure Co and copper-beryllium master alloy, and conventional commercially available pure Cu, pure Co and copper-beryllium master alloy can be used. The present invention can reduce the content of impurities in the alloy by using the above raw materials.

[0038] In the present invention, the smelting temperature is preferably 1100-1300°C, more preferably 1200-1300°C; the present invention has no special limitation on the smelting time, as long as the raw materials of Cu, Co and Be can be completely melted to a molten state. In the present invention, the smelting device is preferably a vacuum induction melting furnace.

[0039] In the present invention, the pressure in the smelting device is preferably 0.03-0.05 MPa, more preferably 0.04-0.05 MPa. The present invention is more conducive to optimizing the melting process, reducing energy consumption and improving production efficiency by controlling the pressure in the smelting device to be within the above range.

[0040] In the present invention, after the raw materials of Cu, Co and Be are completely melted to a molten state, the melt is preferably maintained for 2 to 3 minutes to obtain a Cu-Be-Co melt. In the present invention, by maintaining the melt for a period of time, the components can be mixed more evenly.

[0041] After obtaining the Cu-Be-Co melt, the present invention mixes the copper-coated Sn raw material with the Cu-Be-Co melt and then smelts the mixture to obtain a Cu-Be-Co-Sn alloy melt.

[0042] In the present invention, the copper-coated Sn raw material is preferably Sn particles wrapped in a copper tube. The present invention has no special restrictions on the size and thickness of the copper tube, which can be adjusted as needed. In the present invention, the Sn raw material is preferably Sn particles. The present invention has no special restrictions on the purity of the Sn particles, and conventional commercially available Sn particles can be used. The present invention can prevent the loss of Sn particles during the smelting process and maintain the accuracy of the alloy composition by adding Sn to the copper-coated Sn raw material.

[0043] In the present invention, the method for mixing the copper-coated Sn raw material with the Cu-Be-Co melt is preferably: adding the copper-coated Sn raw material through a built-in rocker arm of a vacuum furnace.

[0044] In the present invention, the smelting temperature is preferably 1100-1300°C, more preferably 1200-1300°C; in the present invention, the smelting time is preferably 3-5 minutes, more preferably 4-5 minutes. The present invention can completely melt the Sn raw material into a molten state by smelting under the above conditions, and because the Sn is added by using a copper-coated Sn raw material, the ignition loss of Sn is small, thereby ensuring the accuracy of the alloy composition and obtaining a high-precision low-beryllium copper alloy ingot. In the present invention, the smelting device is preferably a vacuum induction melting furnace.

[0045] In the present invention, the pressure in the smelting device is preferably 0.03-0.05 MPa, more preferably 0.04-0.05 MPa. The present invention is more conducive to optimizing the melting process, reducing energy consumption and improving production efficiency by controlling the pressure in the smelting device to be within the above range.

[0046] After obtaining the Cu-Be-Co-Sn alloy melt, the present invention casts the Cu-Be-Co-Sn alloy melt to obtain a Cu-Be-Co-Sn alloy ingot.

[0047] The present invention has no special limitation on the casting operation method, and a conventional casting method may be used.

[0048] In the present invention, the Cu-Be-Co-Sn alloy melt is preferably cast and then cooled to room temperature in a furnace to obtain a Cu-Be-Co-Sn alloy ingot.

[0049] After obtaining the Cu-Be-Co-Sn alloy ingot, the present invention sequentially performs solid solution treatment, first cooling, first cold rolling treatment, aging treatment, second cooling and second cold rolling treatment on the Cu-Be-Co-Sn alloy ingot to obtain a stress relaxation resistant low-beryllium copper alloy.

[0050] The present invention preferably cuts the Cu-Be-Co-Sn alloy ingot into block samples before solution treatment. The present invention is more conducive to controlling subsequent operations by cutting the Cu-Be-Co-Sn alloy ingot into block samples. The present invention does not specifically limit the size of the block sample, which can be adjusted as needed.

[0051] In the present invention, the temperature of the solution treatment is preferably 920-950°C, more preferably 930-950°C; the time of the solution treatment is preferably 50-60 minutes, more preferably 60 minutes. The present invention can improve plasticity and toughness, eliminate stress and refine grains through solution treatment.

[0052] In the present invention, the first cooling method is water cooling, and the terminal temperature of the first cooling is room temperature. The present invention can cool the ingot sample after the solution treatment to room temperature through the first cooling, and cool it by water cooling, which can quickly reduce the temperature of the alloy, thereby ensuring that the alloy can be quickly cooled after the solution treatment, which helps to maintain the stability of the supersaturated solid solution and avoid the precipitation of the second phase; and through rapid cooling, the precipitation of the second phase can be suppressed, the structural uniformity of the alloy is maintained, and the performance of the alloy is improved.

[0053] In the present invention, after the first cooling treatment, the oxide layer on the surface of the sample is preferably brushed off with a wire brush. The present invention can reduce impurities in the alloy by removing the oxide layer on the surface of the sample.

[0054] In the present invention, the total rolling reduction of the first cold rolling process is preferably 73-75%, more preferably 74-75%. The present invention is more conducive to refining grains, improving the strength and hardness of the material, and improving its plasticity and toughness by controlling the total rolling reduction of the first cold rolling process within the above range.

[0055] In the present invention, the roll speed of the first cold rolling process is preferably 20-25 r / min, more preferably 20 r / min; the single pass reduction of the first cold rolling process is preferably 4-6%, more preferably 5%; the first cold rolling process is preferably carried out at room temperature. The present invention is more conducive to improving the plasticity and toughness of the alloy by controlling the parameters of the above cold rolling process.

[0056] In the present invention, the temperature of the aging treatment is preferably 430-450°C, more preferably 430-440°C; the time of the aging treatment is preferably 20min-4h, more preferably 40min-60min. In an embodiment of the present invention, the time of the aging treatment can be 20min, 40min, 60min, 2h or 4h. The present invention can release the internal stress inside the alloy through aging treatment, prevent the casting from deformation or cracking due to stress release during use; stabilize the structure and size, eliminate residual stress, ensure the stability of size and shape; improve the hardness and strength of the casting, while maintaining or improving its plasticity and toughness.

[0057] In the present invention, the second cooling method is air cooling, and the end temperature of the second cooling is room temperature. The present invention can cool the ingot sample after aging treatment to room temperature through the second cooling, ensure the impact toughness of the sample, reduce the risk of temper brittleness, and thus ensure the strength and toughness of the test piece.

[0058] In the present invention, after the second cooling treatment, the oxide layer on the surface of the sample is preferably brushed off with a wire brush. The present invention can reduce impurities in the alloy by removing the oxide layer on the surface of the sample.

[0059] In the present invention, the total rolling reduction of the second cold rolling process is preferably 45-50%, more preferably 50%. The present invention is more conducive to refining grains, improving the strength and hardness of the material, and improving its plasticity and toughness by controlling the total rolling reduction of the second cold rolling process within the above range.

[0060] In the present invention, the roll speed of the second cold rolling process is preferably 20-25 r / min, more preferably 20 r / min; the single pass reduction of the second cold rolling process is preferably 4-6%, more preferably 5%; the second cold rolling process is preferably carried out at room temperature. The present invention is more conducive to improving the plasticity and toughness of the alloy by controlling the parameters of the above cold rolling process.

[0061] In the method for preparing the stress relaxation resistant low beryllium copper alloy provided by the present invention, a schematic diagram of the treatment of the Cu-Be-Co-Sn alloy ingot is shown as follows: Figure 1 As shown. Figure 1 It can be seen that the present invention first performs solid solution treatment, water cooling to room temperature, first cold rolling, aging treatment and second cold rolling on the Cu-Be-Co-Sn alloy ingot in sequence to obtain a low-beryllium copper alloy with stress relaxation resistance. The present invention fully precipitates more fine and dispersed BeCo phases in the alloy through solid solution-first cold rolling-aging heat treatment, and the precipitated phase pins the movable dislocations and hinders the movement of dislocations, thereby achieving the purpose of improving the stress relaxation resistance; finally, through the second cold rolling, more dislocations are introduced into the alloy and the grains are refined, and the pinning effect of the second phase and the grain boundary on the dislocations is combined to reduce the density of movable dislocations in the matrix, thereby improving the stress relaxation resistance of the alloy.

[0062] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] Example 1

[0064] A stress relaxation resistant low beryllium copper alloy, which comprises, by mass percentage, 0.1% Be, 0.3% Co, 0.3% Sn and the balance Cu;

[0065] The preparation method of the stress relaxation resistant low beryllium copper alloy is:

[0066] (1) Pure Cu, pure Co and copper-beryllium master alloy are prepared according to the above alloy composition, and the prepared raw materials are added into a melting crucible of a vacuum melting furnace, the cover of the vacuum induction melting furnace is closed, the air in the furnace is extracted, and then argon gas is introduced into the vacuum induction melting furnace to maintain the pressure in the furnace at 0.04 MPa, and the induction heating device of the vacuum induction furnace is turned on to completely melt the raw materials in the melting crucible into a molten state, and keep it for 2 to 3 minutes to obtain a Cu-Be-Co melt; Sn particles are wrapped in a copper tube, and added into the Cu-Be-Co melt through a built-in rocker arm of the vacuum furnace before being taken out of the furnace, and smelted for 3 to 5 minutes to obtain a Cu-Be-Co-Sn alloy melt;

[0067] (2) pouring the Cu—Be—Co—Sn alloy melt obtained in step (1) into a mold, cooling the mold and taking out the ingot to obtain a Cu—Be—Co—Sn alloy ingot;

[0068] (3) The Cu-Be-Co-Sn alloy ingot obtained in the step (2) is cut into block samples by wire cutting, and the ingot is kept at 930° C. for 60 minutes for solution treatment, and then water-cooled to room temperature for first cooling; the ingot after the first cooling is subjected to a first cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 73%; the alloy obtained by the first cold rolling treatment is kept at 430° C. for 20 minutes for aging treatment; after the aging treatment, the alloy is cooled to room temperature by air cooling for second cooling; the alloy after the second cooling is subjected to a second cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 50%, thereby obtaining a low-beryllium copper alloy with stress relaxation resistance.

[0069] Example 2

[0070] A stress relaxation resistant low beryllium copper alloy, which comprises, by mass percentage, 0.2% Be, 0.4% Co, 0.2% Sn and the balance Cu;

[0071] The preparation method of the stress relaxation resistant low beryllium copper alloy is:

[0072] (1) Pure Cu, pure Co and copper-beryllium master alloy are prepared according to the above alloy composition, and the prepared raw materials are added into a melting crucible of a vacuum melting furnace, the cover of the vacuum induction melting furnace is closed, the air in the furnace is extracted, and then argon gas is introduced into the vacuum induction melting furnace to maintain the pressure in the furnace at 0.04 MPa, and the induction heating device of the vacuum induction furnace is turned on to completely melt the raw materials in the melting crucible into a molten state, and keep it for 2 to 3 minutes to obtain a Cu-Be-Co melt; Sn particles are wrapped in a copper tube, and added into the Cu-Be-Co melt through a built-in rocker arm of the vacuum furnace before being taken out of the furnace, and smelted for 3 to 5 minutes to obtain a Cu-Be-Co-Sn alloy melt;

[0073] (2) pouring the Cu—Be—Co—Sn alloy melt obtained in step (1) into a mold, cooling the mold and taking out the ingot to obtain a Cu—Be—Co—Sn alloy ingot;

[0074] (3) The Cu-Be-Co-Sn alloy ingot obtained in the step (2) is cut into block samples by wire cutting, and the ingot is kept at 950° C. for 60 minutes for solution treatment, and then water-cooled to room temperature for first cooling; the first cooled ingot is subjected to first cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling treatment, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 75%; the alloy obtained by the first cold rolling treatment is kept at 440° C. for 40 minutes for aging treatment; after the aging treatment, the alloy is cooled to room temperature by air cooling for second cooling; the second cooled alloy is subjected to second cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling treatment, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 50% to obtain a low-beryllium copper alloy with stress relaxation resistance.

[0075] Example 3

[0076] A stress relaxation resistant low beryllium copper alloy, which comprises, by mass percentage, 0.3% Be, 0.5% Co, 0.2% Sn and the balance Cu;

[0077] The preparation method of the stress relaxation resistant low beryllium copper alloy is:

[0078] (1) Pure Cu, pure Co and copper-beryllium master alloy are prepared according to the above alloy composition, and the prepared raw materials are added into a melting crucible of a vacuum melting furnace, the cover of the vacuum induction melting furnace is closed, the air in the furnace is extracted, and then argon gas is introduced into the vacuum induction melting furnace to maintain the pressure in the furnace at 0.04 MPa, and the induction heating device of the vacuum induction furnace is turned on to completely melt the raw materials in the melting crucible into a molten state, and keep it for 2 to 3 minutes to obtain a Cu-Be-Co melt; Sn particles are wrapped in a copper tube, and added into the Cu-Be-Co melt through a built-in rocker arm of the vacuum furnace before being taken out of the furnace, and smelted for 3 to 5 minutes to obtain a Cu-Be-Co-Sn alloy melt;

[0079] (2) pouring the Cu—Be—Co—Sn alloy melt obtained in step (1) into a mold, cooling the mold and taking out the ingot to obtain a Cu—Be—Co—Sn alloy ingot;

[0080] (3) The Cu-Be-Co-Sn alloy ingot obtained in the step (2) is cut into block samples by wire cutting, and the ingot is kept at 950° C. for 60 minutes for solution treatment, and then water-cooled to room temperature for first cooling; the ingot after the first cooling is subjected to a first cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 75%; the alloy obtained by the first cold rolling treatment is kept at 450° C. for 60 minutes for aging treatment; after the aging treatment, the alloy is cooled to room temperature by air cooling for second cooling; the alloy after the second cooling is subjected to a second cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 50% to obtain a low-beryllium copper alloy with stress relaxation resistance.

[0081] Example 4

[0082] A stress relaxation resistant low beryllium copper alloy, which comprises, by mass percentage, 0.5% Be, 0.5% Co, 0.3% Sn and the balance Cu;

[0083] The preparation method of the stress relaxation resistant low beryllium copper alloy is:

[0084] (1) Pure Cu, pure Co and copper-beryllium master alloy are prepared according to the above alloy composition, and the prepared raw materials are added into a melting crucible of a vacuum melting furnace, the cover of the vacuum induction melting furnace is closed, the air in the furnace is extracted, and then argon gas is introduced into the vacuum induction melting furnace to maintain the pressure in the furnace at 0.04 MPa, and the induction heating device of the vacuum induction furnace is turned on to completely melt the raw materials in the melting crucible into a molten state, and keep it for 2 to 3 minutes to obtain a Cu-Be-Co melt; Sn particles are wrapped in a copper tube, and added into the Cu-Be-Co melt through a built-in rocker arm of the vacuum furnace before being taken out of the furnace, and smelted for 3 to 5 minutes to obtain a Cu-Be-Co-Sn alloy melt;

[0085] (2) pouring the Cu—Be—Co—Sn alloy melt obtained in step (1) into a mold, cooling the mold and taking out the ingot to obtain a Cu—Be—Co—Sn alloy ingot;

[0086] (3) The Cu-Be-Co-Sn alloy ingot obtained in the step (2) is cut into block samples by wire cutting, and the ingot is kept at 920° C. for 60 minutes for solution treatment, and then water-cooled to room temperature for first cooling; the ingot after the first cooling is subjected to a first cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 73%; the alloy obtained by the first cold rolling treatment is kept at 430° C. for 40 minutes for aging treatment; after the aging treatment, the alloy is cooled to room temperature by air cooling for second cooling; the alloy after the second cooling is subjected to a second cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 45%, thereby obtaining a low-beryllium copper alloy with stress relaxation resistance.

[0087] Example 5

[0088] A stress relaxation resistant low beryllium copper alloy, which comprises, by mass percentage, 0.4% Be, 0.5% Co, 0.2% Sn and the balance Cu;

[0089] The preparation method of the stress relaxation resistant low beryllium copper alloy is:

[0090] (1) Pure Cu, pure Co and copper-beryllium master alloy are prepared according to the above alloy composition, and the prepared raw materials are added into a melting crucible of a vacuum melting furnace, the cover of the vacuum induction melting furnace is closed, the air in the furnace is extracted, and then argon gas is introduced into the vacuum induction melting furnace to maintain the pressure in the furnace at 0.04 MPa, and the induction heating device of the vacuum induction furnace is turned on to completely melt the raw materials in the melting crucible into a molten state, and keep it for 2 to 3 minutes to obtain a Cu-Be-Co melt; Sn particles are wrapped in a copper tube, and added into the Cu-Be-Co melt through a built-in rocker arm of the vacuum furnace before being taken out of the furnace, and smelted for 3 to 5 minutes to obtain a Cu-Be-Co-Sn alloy melt;

[0091] (2) pouring the Cu—Be—Co—Sn alloy melt obtained in step (1) into a mold, cooling the mold and taking out the ingot to obtain a Cu—Be—Co—Sn alloy ingot;

[0092] (3) The Cu-Be-Co-Sn alloy ingot obtained in the step (2) is cut into block samples by wire cutting, and the ingot is kept at 950° C. for 60 minutes for solution treatment, and then water-cooled to room temperature for first cooling; the ingot after the first cooling is subjected to a first cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 75%; the alloy obtained by the first cold rolling treatment is kept at 440° C. for 2 hours for aging treatment; after the aging treatment, the alloy is cooled to room temperature by air cooling for second cooling; the alloy after the second cooling is subjected to a second cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 50%, thereby obtaining a low-beryllium copper alloy with stress relaxation resistance.

[0093] Example 6

[0094] A stress relaxation resistant low beryllium copper alloy, which comprises, by mass percentage, 0.2% Be, 0.2% Co, 0.3% Sn and the balance Cu;

[0095] The preparation method of the stress relaxation resistant low beryllium copper alloy is:

[0096] (1) Pure Cu, pure Co and copper-beryllium master alloy are prepared according to the above alloy composition, and the prepared raw materials are added into a melting crucible of a vacuum melting furnace, the cover of the vacuum induction melting furnace is closed, the air in the furnace is extracted, and then argon gas is introduced into the vacuum induction melting furnace to maintain the pressure in the furnace at 0.04 MPa, and the induction heating device of the vacuum induction furnace is turned on to completely melt the raw materials in the melting crucible into a molten state, and keep it for 2 to 3 minutes to obtain a Cu-Be-Co melt; Sn particles are wrapped in a copper tube, and added into the Cu-Be-Co melt through a built-in rocker arm of the vacuum furnace before being taken out of the furnace, and smelted for 3 to 5 minutes to obtain a Cu-Be-Co-Sn alloy melt;

[0097] (2) pouring the Cu—Be—Co—Sn alloy melt obtained in step (1) into a mold, cooling the mold and taking out the ingot to obtain a Cu—Be—Co—Sn alloy ingot;

[0098] (3) The Cu-Be-Co-Sn alloy ingot obtained in the step (2) is cut into block samples by wire cutting, and the ingot is kept at 940° C. for 60 minutes for solution treatment, and then water-cooled to room temperature for first cooling; the first cooled ingot is subjected to first cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling treatment, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 75%; the alloy obtained by the first cold rolling treatment is kept at 430° C. for 4 hours for aging treatment; after the aging treatment, the alloy is cooled to room temperature by air cooling for second cooling; the second cooled alloy is subjected to second cold rolling treatment, and the oxide layer on the surface of the sample is brushed off with a wire brush before rolling treatment, and then the ingot is rolled down by 5% in a single pass at room temperature and a rolling speed of 20 r / min, and the total rolling reduction is 50% to obtain a low-beryllium copper alloy with stress relaxation resistance.

[0099] Test Case

[0100] (1) In the process of preparing the stress relaxation resistant low beryllium copper alloy in Examples 1 to 6, the hardness value change curve of the sample after aging treatment is as follows: Figure 2 As shown. Figure 2 It can be seen that the hardness values ​​of the samples after aging treatment in Examples 1 to 6 are 240 to 260 HV. This is because when preparing the stress relaxation resistant low beryllium copper alloy, the hardness value of the beryllium copper alloy can be increased by adding the aging process.

[0101] (2) In the process of preparing the stress relaxation-resistant low-beryllium copper alloy provided in Examples 1 to 6, the conductivity change curve of the sample after aging treatment is as follows: Figure 3 As shown. Figure 3 It can be seen that the conductivity of the samples in Examples 1 to 6 after aging treatment is 52 to 55% IACS, which has a relatively high conductivity.

[0102] (3) The tensile mechanical property curve of the stress relaxation resistant low beryllium copper alloy provided in Example 3 is as follows: Figure 4 As shown. Figure 4 It can be seen that the tensile strength of the stress relaxation resistant low beryllium copper alloy provided in Example 3 can reach 750-800 MPa.

[0103] (4) The stress relaxation resistance performance curve of the low beryllium copper alloy provided in Example 3 is as follows: Figure 5 As shown. Figure 5 It can be seen that the stress relaxation rate of the stress relaxation-resistant low-beryllium copper provided in Example 3 is maintained at about 10% during the entire test period, and has excellent stress relaxation resistance.

[0104] It can be seen from the above results that the stress relaxation resistant low beryllium copper alloy provided by the present invention has high strength, high conductivity and excellent stress relaxation resistance. This is because the present invention obtains a high-strength, high-conductivity, low beryllium copper alloy with excellent stress relaxation resistance by designing the composition of the low beryllium copper alloy (controlling the content of Be, Co and Sn elements in the alloy) and optimizing the heat treatment and rolling deformation (setting the solid solution, aging heat treatment parameters and rolling deformation parameters).

[0105] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A stress relaxation resistant low beryllium copper alloy, comprising, by mass percentage: Be 0.1-0.5%, Co 0.1-0.5%, Sn 0.1-0.3% and the balance Cu.

2. The method for preparing the stress relaxation resistant low beryllium copper alloy according to claim 1, comprising the following steps: (1) smelting raw materials of Cu, Co and Be to obtain a Cu-Be-Co melt; mixing a copper-coated Sn raw material with the Cu-Be-Co melt and smelting the mixture to obtain a Cu-Be-Co-Sn alloy melt; (2) casting the Cu—Be—Co—Sn alloy melt obtained in step (1) to obtain a Cu—Be—Co—Sn alloy ingot; (3) The Cu-Be-Co-Sn alloy ingot obtained in step (2) is subjected to solution treatment, first cooling, first cold rolling, aging treatment, second cooling and second cold rolling in sequence to obtain a high-strength, high-conductivity, stress-relaxation-resistant, low-beryllium copper alloy.

3. The preparation method according to claim 2, characterized in that: The smelting temperature in the step (1) is 1100-1300°C.

4. The preparation method according to claim 2, characterized in that: The temperature of the solution treatment in step (3) is 920-950° C. and the time of the solution treatment is 50-60 min.

5. The preparation method according to claim 2, characterized in that: The first cooling method in step (3) is water cooling.

6. The preparation method according to claim 2 or 5, characterized in that: The second cooling method in step (3) is air cooling.

7. The preparation method according to claim 2, characterized in that: The total rolling reduction in the first cold rolling process in step (3) is 73-75%.

8. The preparation method according to claim 2, characterized in that: The temperature of the aging treatment in step (3) is 430-450°C.

9. The preparation method according to claim 2 or 8, characterized in that: The time of aging treatment in step (3) is 20 minutes to 4 hours.

10. The preparation method according to claim 2, characterized in that: The total rolling reduction of the second cold rolling process in step (3) is 45 to 50%.

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