Copper alloy for connector and preparation method thereof

Abstract

The invention provides a copper alloy for a connector and a preparation method thereof, and the copper alloy for the connector comprises the following components in percentage by weight: 2.0-4.0% of Ni; 0.4 to 1.2 percent of Si; 0.02 to 0.3 percent of Mg; mn: 0.001 to 0.2%; 0.001 to 0.05 percent of P (phosphorus); 0-0.2% of X, and the balance Cu and inevitable impurities, and the content of the impurities is less than 0.5%; wherein X is one or more of Nb, Zr and Cr. The preparation method of the copper alloy comprises the steps of smelting, casting, extrusion traction, machining, solid solution treatment, heat treatment and finished product stretching, and the microstructure of the copper alloy is regulated and controlled through process design and component adjustment, so that the copper alloy has the comprehensive performance of high strength, high conductivity, good heat resistance and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of copper alloys, and in particular to a copper alloy for a connector and a preparation method thereof. Background Art

[0002] In recent years, with the rapid growth of global demand for electronic products, the semiconductor industry has gradually become the core of the modern electronic industry, and its product technology has developed extremely rapidly. Among them, the PIN pins in semiconductor components are accessories used in connectors to complete the transmission of electrical signals, and their role is particularly critical. Therefore, the material selection, processing, comprehensive performance and precision consistency of the PIN pins are very important for the performance of the entire electronic system. If the PIN pins are bent or deviated during processing or use, it will seriously affect the subsequent assembly and functional performance.

[0003] Currently, the PIN materials for semiconductor connectors on the market are mainly oxygen-free copper products. Although oxygen-free copper has excellent electrical conductivity and processing plasticity, its material strength and high temperature resistance are average. Since some semiconductor products need to work in high temperature environments, the connecting components are required to have good high temperature and high voltage resistance. Although the tin bronze fine wire products have good material mechanical properties, their electrical conductivity cannot meet the requirements. The production cost of brass alloy fine wire products is low, but their electrical conductivity and heat resistance are also average, and they cannot meet the high requirements of PIN processing and use conditions. Summary of the invention

[0004] In view of the above problems, the first object of the present invention is to provide a copper alloy for a connector, which has comprehensive properties such as high strength, high conductivity, and good heat resistance, and meets the current processing and use requirements of semiconductor PIN needle products.

[0005] The second object of the present invention is to provide a method for preparing a copper alloy for a connector, and to control the microstructure of the copper alloy through process design to optimize the comprehensive performance of the copper alloy.

[0006] A first aspect of the present invention provides a copper alloy for a connector. The composition of the copper alloy for a connector is, by mass percentage, Ni: 2.0-4.0%; Si: 0.4-1.2%; Mg: 0.02-0.3%; Mn: 0.001-0.2%; P: 0.001-0.05%; X: 0-0.2%, the remainder being Cu and unavoidable impurities, and the impurities are <0.5%; wherein X is one or more of Nb, Zr, and Cr.

[0007] Preferably, the composition of the copper alloy for the connector is, by weight percentage: Ni: 2.0~4.0%; Si: 0.4~1.2%; Mg: 0.02~0.3%; Mn: 0.001~0.2%; P: 0.001~0.05%; Nb 0.001~0.1%, Zr 1.001~0.1%, Cr 0.001~0.1%, and the remainder is Cu and unavoidable impurities, and the impurities are <0.5%.

[0008] Preferably, the phase structure of the copper alloy for connector includes copper α phase and precipitation strengthening phase, and the precipitation strengthening phase includes: one or more of NiSi phase, MnSi phase, NiP phase, CrSi phase and the like.

[0009] Preferably, the average grain size of the copper alloy for connector is ≤5 μm, the size of precipitated phase is <200 nm, and the distribution number of precipitated phase is 1*10 6 ~6*10 6 Pieces / mm 2 , the NiSi phase accounts for more than 90% of the precipitation strengthening phase.

[0010] In the copper alloy of the present invention, Ni and Si are used as main additive elements to form a NiSi precipitated phase mainly in the form of Ni2Si compound, which can greatly improve the material strength, hardness, electrical conductivity and high temperature resistance. At the same time, Ni can be infinitely dissolved with the Cu matrix to further improve the material strength. However, it is necessary to control the upper limit of Ni addition to 4% to avoid excessive addition causing the material to be hot-processed and plastic, affecting the extrusion processing quality, and also effectively controlling the raw material cost. The solid solubility of Si element in the Cu matrix is ​​relatively low, so under the premise of determining the Ni element range, the Si element content range is effectively controlled. If the Si element addition is low, it is difficult to form a sufficient number of NiSi precipitated phases, and the mechanical properties, electrical conductivity and heat resistance of the material cannot be effectively guaranteed. If the Si element addition is too large, the electrical conductivity of the material will be greatly reduced, and the material plasticity will also deteriorate, which cannot meet the processing quality of PIN needle cold heading, bending, etc.

[0011] The Mg element can gather in the Cu matrix in the form of approximate atomic gas clusters to increase the density of the precipitated phase during the aging process. At the same time, the Mg element can hinder dislocation movement to a certain extent, improve the processing deformation plasticity of the material, and reduce the risk of cracking when the material is subjected to high processing rate cold deformation processing. In the present invention, the amount of Mg added needs to be controlled to an upper limit of 0.3%. If the amount added is too high, on the one hand, the electrical conductivity will be reduced. On the other hand, the solid solubility of Mg in the Cu matrix is ​​extremely low, and excessive Mg is distributed on the grain boundaries to easily form a certain number of brittle phases, which will reduce the mechanical properties and processing plasticity of the material.

[0012] The Mn element can form a MnSi precipitate phase with Si to further improve the strength and wear resistance of the material. Among them, the MnSi precipitate phase mainly exists in the form of a Mn5Si3 compound. In the present invention, the upper limit of the amount of Mn element addition needs to be controlled to be 0.2%. If the amount of Mn element addition is too high, on the one hand, the electrical conductivity will be reduced, and on the other hand, the melt viscosity will be increased during the smelting process, and the melt fluidity will be reduced, thereby deteriorating the casting quality of the product.

[0013] The addition of P element improves the melt fluidity during the casting process and improves the casting quality. At the same time, trace P element can form NiP compound with Ni, which plays a certain precipitation strengthening role. In the present invention, the upper limit of the amount of P element added needs to be controlled to 0.05%. If the amount added is too high, the electrical conductivity and mechanical properties of the material will be greatly reduced.

[0014] The addition of Nd element can inhibit the formation of coarse precipitation phase during the aging process, increase the precipitation rate and amount of NiSi precipitation phase, and delay the increase of grains during solid solution, thereby further improving the mechanical properties and heat resistance of the material.

[0015] The addition of Zr element can promote the formation of nucleation points, play a role in grain refinement, improve the uniformity of material structure, and indirectly improve the mechanical properties of the material.

[0016] The addition of Cr element can form Cr3Si compound with Si, which can improve the high temperature stability of the material and obtain good anti-softening performance. At the same time, trace Cr element can also improve the plasticity and conductivity of the material.

[0017] A second aspect of the present invention provides a method for preparing a copper alloy for a connector, and the specific steps of the preparation method are as follows: Step S1: Melting: Mix the ingredients according to the required composition ratio, and put the raw materials or recycled materials into the melting furnace for melting; Step S2: introducing molten copper into a crystallizer for continuous casting of ingots, controlling the temperature of the molten copper when it flows into the crystallizer to be 1220-1300° C., and sawing and surface processing the pulled copper ingots as required; Step S3: extruding the ingot, the extrusion heating temperature is 850-950°C; and performing a solid solution treatment immediately after the extrusion; Step S4: processing the extruded blank with a processing rate of 50-90%; then subjecting the deformed blank to a solid solution treatment to obtain a wire blank, which is rapidly cooled after being taken out of the furnace; and then processing the cooled wire blank with a processing rate of 60-95%; Step S5: heat-treating the blank processed in step S4, and then continuously stretching the blank with a processing rate of 60-95%; and performing online induction annealing heat treatment to obtain the copper alloy for the connector.

[0018] Preferably, the continuous casting method in step S2 is semi-continuous casting or horizontal continuous casting.

[0019] Preferably, in step S2, the specific conditions for traction are: a traction speed of 20-60 mm / min.

[0020] Preferably, in step S3, the properties of the billet produced by extrusion are as follows: elongation ≥ 30%, electrical conductivity ≤ 25% IACS, and average grain size ≤ 0.2 mm.

[0021] The extrusion process of the present invention realizes the simultaneous extrusion and solution treatment processes, and utilizes the residual heat of extrusion heating without the need to reheat and solution treat the blank. On the one hand, it shortens the process and improves production efficiency, and on the other hand, it avoids the appearance of coarse grains in the material caused by multiple heating. The blank produced by the extrusion process can achieve a good solution effect, which is beneficial to the subsequent aging strengthening process. At the same time, the material processing plasticity also meets the requirements of the next high processing rate cold deformation process.

[0022] In order to achieve efficient production and avoid the appearance of coarse grains, the extrusion process of the present invention needs to simultaneously control the conditions of heating temperature, extrusion ratio and extrusion speed. Preferably, in step S3, the specific conditions of the extrusion are: extrusion heating temperature is 850-950°C, extrusion ratio is 30-100:1; extrusion speed is 5-12 mm / s; And / or, in step S3, the conditions of the solution treatment are: controlling the temperature of the blank before entering the water to 700-950°C, and the cooling water temperature to <60°C.

[0023] The inventors found in their research that in the extrusion process, if the extrusion temperature is too low, the deformation plasticity of the alloy during the extrusion process is poor, and it is impossible to achieve a large extrusion ratio, the grains cannot be fully broken, and it is difficult to obtain a uniform organizational morphology; if the extrusion temperature is too high, on the one hand, the grains will grow under long-term heating conditions, and the proportion of extruded organizational non-uniformity will increase. On the other hand, the hot brittleness of elements such as Si and Mg will increase, and transverse cracking is likely to occur during the extrusion process, and the extrusion quality cannot meet the requirements. If the extrusion ratio is too low, the extrusion deformation is too small, and the grains cannot be fully broken and refined; if the extrusion ratio is too high, the resistance to extrusion deformation will increase significantly, and the probability of extrusion cracking or ingot stuffiness will increase significantly. At the same time, if the extrusion speed is too low, the required extrusion time will increase, and the extrusion process will be accompanied by temperature loss, resulting in an increase in the performance difference between the extrusion head and tail; if the extrusion speed is too fast, the difference between the compressive stress and the tensile stress of the inner and outer layers of the extruded billet will further increase, which is prone to the risk of extrusion cracking.

[0024] At the same time, in step S3, solution treatment is carried out immediately after extrusion, and the temperature of the blank before entering the water is controlled to be 700~950℃, and the cooling water temperature is less than 60℃, in order to obtain a good solution softening effect for the extruded blank, so as to reduce the formation of precipitation phases in this process, avoid increasing the strength and hardness of the blank and reducing its plasticity, and affect subsequent processing. The temperature of the blank before entering the water is controlled to be slightly lower than the extrusion temperature of the material and not lower than 700℃, in order to achieve a good solution effect. If the temperature before entering the water is lower than 700℃, the material will be accompanied by the formation of some precipitation phases. At the same time, if the cooling temperature is too high, the solution effect will be greatly reduced, and the grains of the extruded blank cannot be fully refined.

[0025] Preferably, the processing in step S4 is cold processing, and the cold processing includes any one of rolling, continuous drawing, and coil drawing. Those skilled in the art can make a selection according to actual production.

[0026] Preferably, the processing in step S4 is at least one processing. If at least two processing steps are used, annealing and softening treatment is performed between each step, with an annealing temperature of 650-800° C. and a holding time of 30-300 min.

[0027] If rolling is used, multi-roll rolling equipment is used to roll the steel sheet to the required specifications online at one time. If continuous drawing is used, continuous drawing equipment is used to stretch the steel sheet to the required specifications online at one time using multiple molds. If coil drawing is used, coil drawing equipment is used for stretching. After the processing rate reaches 30-60%, intermediate softening annealing can be added, and coil drawing can be continued after annealing.

[0028] In step S4 of the present invention, a cold working deformation treatment with a processing rate of 50-90% is first performed to fully refine the grains and form an appropriate amount of dislocations, thereby providing a primary phase and a channel for the subsequent precipitation of the aging strengthening phase, which is beneficial to ultimately obtaining an ideal microstructure. At the same time, deformation with a high processing rate is also beneficial to obtaining ideal mechanical properties.

[0029] Preferably, the conditions for the solution treatment in step S4 are: solution temperature: 700-800°C, holding time 2-60 min; And / or, the cooling rate of the wire embryo after being taken out of the furnace is greater than 200° C. / s.

[0030] In the present invention, solution treatment is one of the important processes, which directly affects the comprehensive performance of the finished product. The present invention controls the solution temperature range to be 700-800°C, which is close to the lower limit temperature range of the material solution. If the temperature is too low, the precipitated phase cannot be fully dissolved in the matrix, and the subsequent aging process cannot fully improve the material strength and conductivity. If the temperature is too high, although the solution effect is more sufficient, the grains are prone to grow, and the uniformity of the organization is general, which is not conducive to the quality of the subsequent PIN needle cold heading processing.

[0031] At the same time, the holding time is controlled to be 2 to 60 minutes. If the holding time is too long, the grains will also grow under the solid solution condition, so the present invention controls the solid solution holding time to be no more than 60 minutes. At the same time, in order to ensure that the blank obtains a good solid solution effect after being heated out of the furnace, the present invention controls the cooling rate of the blank after it is out of the furnace to be no less than 200°C / s.

[0032] The solution treatment described in the present invention can be carried out by online solution treatment or offline solution treatment, which is not specifically limited in the present invention and can be selected by those skilled in the art according to actual production needs.

[0033] Preferably, the heat treatment conditions in step S5 are: aging temperature: 380-500°C, holding time: 30-600min; Preferably, the processing rate of the continuous stretching process in step S5 is 60-95%; the stretching speed is 300-1000 m / min; And / or, the annealing voltage of the online induction annealing heat treatment is 40-60V.

[0034] Heat treatment is also one of the important processes in the preparation method of the present invention. In the present invention, the aging temperature is controlled to be 380~500℃ to ensure that the precipitated phase is fully precipitated from the matrix, so that the electrical conductivity and mechanical properties of the material are fully improved. If the aging temperature is too low, on the one hand, it is difficult to transform the ordered phase into a stable precipitated phase, the amount of precipitated phase cannot reach the ideal value, and the strengthening effect cannot meet the actual performance requirements. On the other hand, the temperature is too low and the recrystallization effect of the material is not sufficient. The residual processed structure in the structure is difficult to be transformed into recrystallized equiaxed grains, and the uniformity of the microstructure also cannot meet the performance requirements. If the aging temperature is too high, although the electrical conductivity can be further improved, the material is prone to softening, and the precipitated phase will also have the problem of excessive growth, which is not conducive to achieving the ideal strengthening effect, and the mechanical properties cannot meet the requirements. This process effectively controls the size of the precipitated phase to be less than 200nm, and the distribution number of the precipitated phase is 1*10 6 ~6*10 6 Pieces / mm 2 .

[0035] In step S5, the desired finished product specifications are obtained through continuous stretching processing, so that the material is further hardened and the strength and hardness are improved. In order to ensure the subsequent cold heading processing of the PIN needle, the material is required to meet the high strength and also obtain high elongation deformation plasticity. Therefore, after the finished product is stretched, an online induction annealing heat treatment is performed to further improve the elongation without significantly reducing the material strength.

[0036] Preferably, the properties of the copper alloy for the connector are as follows: tensile strength ≥500 MPa, elongation ≥15%, electrical conductivity ≥40% IACS, and softening temperature ≥520°C.

[0037] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, by adjusting the composition, controlling the addition of specific elements and the proportion of elements, the copper alloy obtained contains precipitated phases such as NiSi and MnSi, which greatly improves the strength, hardness, conductivity and high temperature resistance of the material. With special process design, the microstructure performance is regulated to make the material have comprehensive properties such as high strength, high conductivity and good heat resistance, which meets the current cold heading and bending processing requirements of semiconductor PIN needle products, and the comprehensive performance is better than the conventional copper, brass and bronze products used in connectors on the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0039] Figure 1 This is the metallographic structure diagram of the copper alloy of Example 1 of the present invention.

[0040] Figure 2 This is a SEM image of the copper alloy of Example 1 of the present invention.

[0041] Figure 3 This is the metallographic structure diagram of the copper alloy of Comparative Example 1 of the present invention.

[0042] Figure 4 This is the metallographic structure diagram of the copper alloy of Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0043] Those skilled in the art can refer to the content of this article and appropriately replace and / or modify the process parameters to achieve the same. However, it should be particularly noted that all similar replacements and / or modifications are obvious to those skilled in the art and are considered to be included in the present invention. The products and preparation methods described in the present invention have been described through preferred examples. It is obvious that relevant personnel can modify or appropriately change and combine the products and preparation methods described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0044] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. The present invention uses the methods and materials described herein; however, other suitable methods and materials known in the art may also be used. The materials, methods, and examples described herein are illustrative only and are not intended to be limiting. All publications, patent applications, patents, provisional applications, database entries, and other references mentioned herein are incorporated herein by reference in their entirety. In the event of a conflict, the present specification, including definitions, shall prevail.

[0045] Unless otherwise specified, all percentages, parts, ratios, etc. are by weight; otherwise specified, including but not limited to, "wt%" means weight percentage, "mol%" means molar percentage, and "vol%" means volume percentage.

[0046] When a quantity, concentration or other numerical value or parameter is given as a range, a preferred range or a series of upper preferred values ​​and lower preferred values, it should be understood that it specifically discloses all ranges formed by any pair of numerical values ​​of any larger range limit or preferred value and any smaller range limit or preferred value, regardless of whether the range is disclosed separately. For example, when describing a range of "1 to 5 (1~5)", the described range should be understood to include a range of "1 to 4 (1~4)", "1 to 3 (1~3)", "1 to 2 (1~2)", "1 to 2 (1~2) and 4 to 5 (4~5)", "1 to 3 (1~3) and 5" and the like. Unless otherwise stated, where a numerical range is described herein, the range is intended to include the range end values ​​and all integers and fractions within the range.

[0047] When the term "about" is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to.

[0048] In addition, unless expressly stated to the contrary, "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following conditions applies to condition A "or" B: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist).

[0049] In addition, the indefinite articles "a" and "an" before the elements or components of the present invention are intended to indicate that the number of occurrences (i.e., occurrences) of the elements or components is not limited. Therefore, "a" or "an" should be understood to include one or at least one, and unless it is clearly indicated that the number is singular, the elements or components in the singular form also include the plural case.

[0050] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions. The sentence "includes an element defined by ...... does not exclude the existence of other identical elements in the process, method, article or device including the element".

[0051] Unless specifically stated, the materials, methods, and examples described herein are illustrative only and not limiting. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are still described herein.

[0052] The contents of the present invention are described in detail below.

[0053] According to one embodiment of the present invention, a copper alloy for a connector, the raw material composition of the copper alloy for the connector, measured by weight percentage, is: Ni: 2.0~4.0%; Si: 0.4~1.2%; Mg: 0.02~0.3%; Mn: 0.001~0.2%; P: 0.001~0.05%; X: 0~0.2%, the remainder is Cu and unavoidable impurities, and the impurities are <0.5%; wherein X is one or more of Nb, Zr, and Cr.

[0054] The phase structure of the copper alloy for connectors includes copper α phase and precipitation strengthening phase, and the precipitation strengthening phase includes one or more of NiSi phase, MnSi phase, NiP phase, CrSi phase, etc. The average grain size of the copper alloy is ≤5μm, the precipitation phase size is <200nm, and the precipitation phase distribution number is 1*10 6 ~6*10 6 Pieces / mm 2 , the NiSi phase accounts for more than 90% of the precipitation strengthening phase.

[0055] According to a preferred embodiment of the present invention, the composition of the connector copper alloy is as follows by weight percentage: Ni: 2.0~4.0%; Si: 0.4~1.2%; Mg: 0.02~0.3%; Mn: 0.001~0.2%; P: 0.001~0.05%; Nb0.001~0.1%, Zr 0.001~0.1%, Cr 0.001~0.1%, the remainder is Cu and unavoidable impurities, and the impurities are less than 0.5%. The phase structure of the copper alloy includes copper α phase and precipitation strengthening phase, and the precipitation strengthening phase includes: one or more of NiSi phase, MnSi phase, NiP phase, CrSi phase, etc.

[0056] The average grain size of copper alloy is ≤5μm, the precipitate size is <200nm, and the precipitate distribution number is 1*10 6 ~6*10 6 Pieces / mm 2 , the NiSi phase accounts for more than 90% of the precipitation strengthening phase.

[0057] According to one embodiment of the present invention, a method for preparing a copper alloy for a connector comprises the following specific steps: (1) Melting: The raw materials or recycled materials are placed in the melting furnace for melting according to the required proportion of ingredients.

[0058] (2) Casting: The ingots are cast by semi-continuous casting or horizontal continuous casting. The molten copper is introduced into the crystallizer for continuous casting. The temperature of the molten copper when it flows into the crystallizer is controlled to be 1220~1300℃, and the pulling speed is 20~60mm / min. The pulled copper ingots are sawed and surface processed as required.

[0059] (3) Extrusion: The ingot is extruded, the extrusion heating temperature is 850~950℃, the extrusion ratio is 30~100:1; the extrusion speed is 5~12mm / s; the solid solution treatment is carried out immediately after the extrusion, and the temperature of the blank before entering the water is controlled to be: 700~950℃, and the cooling water temperature is <60℃; the properties of the billet obtained by extrusion are: elongation ≥30%, conductivity ≤25%IACS, and average grain size ≤0.2mm.

[0060] (4) Processing: The billet obtained by extrusion is subjected to rolling or stretching deformation, with a processing rate of 50~90%; if multiple passes are performed, the intermediate annealing and softening process is controlled as follows: annealing temperature: 650~800℃, holding time 30~300min.

[0061] (5) Solution treatment: The processed billet is subjected to solution treatment to obtain a wire blank. The solution temperature is 700-800°C and the holding time is 2-60 min. After the wire blank is taken out of the furnace, it is rapidly cooled at a cooling rate of >200°C / s.

[0062] (6) Deformation after bottom solution treatment: The wire embryo after bottom solution treatment is subjected to rolling or continuous stretching deformation, with a processing rate of 60~95%.

[0063] (7) Heat treatment: The billet after bottom processing and deformation is subjected to aging heat treatment, the aging temperature is 380~500℃, and the holding time is 30~600min.

[0064] (8) Finished product stretching: The heat-treated blank is continuously stretched, with a processing rate of 60-95%. The stretching speed is 300-1000 m / min, and online induction annealing heat treatment is performed, with an annealing voltage of 40-60 V.

[0065] The present invention will be described below in conjunction with the embodiments of the accompanying drawings. However, the present invention can be implemented in various different ways and is not limited to the embodiments described herein.

[0066] The raw material proportions of the copper alloys of Examples 1-6 and Comparative Examples 1-7 are shown in Tables 1 and 2 below.

[0067] Table 1

[0068] Table 2

[0069] Example 1 This embodiment provides a method for preparing a copper alloy for a connector, and the specific steps are as follows: (1) Melting: Prepare the ingredients according to the composition ratio requirements in Table 1 and place the raw materials into a melting furnace for melting; the melting temperature is 1300°C.

[0070] (2) Casting: The semi-continuous casting process is used to cast ingots. The molten copper is introduced into the crystallizer for continuous casting. The temperature of the molten copper when it flows into the crystallizer is controlled to be 1240°C, and the pulling speed is 55 mm / min. The pulled copper ingots are sawed and surface processed as required to obtain φ250 mm specification ingot blanks.

[0071] (3) Extrusion: The ingot is extruded, the extrusion heating temperature is 860°C, the extrusion ratio is 78:1, the extrusion speed is 12 mm / s, and the solid solution treatment is immediately carried out after the extrusion. The temperature of the blank before entering the water is controlled to be 730°C, and the cooling water temperature is <60°C. A φ20 mm extruded blank is obtained.

[0072] (4) Processing: The extruded billet is rolled online once using an 8-roll rolling machine with a processing rate of 84% to obtain a φ8 mm billet.

[0073] (5) Solution treatment: The cold-deformed billet is solution treated to obtain a wire blank. The solution temperature is 720°C and the holding time is 6 minutes. After the wire blank is taken out of the furnace, it is quickly cooled by water.

[0074] (6) Deformation after bottom solution treatment: The blank after bottom solution treatment is subjected to continuous stretching deformation with a processing rate of 86%.

[0075] (7) Heat treatment: The billet after bottom processing and deformation is subjected to aging heat treatment, aging temperature: 390°C, holding time: 180 min.

[0076] (8) Finished product stretching: The heat-treated blank is subjected to continuous stretching processing with a processing rate of 84%; the stretching speed is 500 m / min, and an online induction annealing heat treatment is performed with an annealing voltage of 45 V to obtain a φ1.2 mm finished product.

[0077] Depend on Figure 1 and Figure 2 It can be seen that the copper alloy obtained has fine grains and good uniformity.

[0078] Example 2 This embodiment provides a method for preparing a copper alloy for a connector, and the specific steps are as follows: (1) Melting: Prepare the ingredients according to the composition ratio requirements in Table 1 and place the raw materials into a melting furnace for melting; the melting temperature is 1350°C.

[0079] (2) Casting: The semi-continuous casting process is used to cast ingots. The molten copper is introduced into the crystallizer for continuous casting. The temperature of the molten copper when it flows into the crystallizer is controlled to be 1260°C, and the pulling speed is 50 mm / min. The pulled copper ingots are sawed and surface processed as required to obtain φ250 mm specification ingot blanks.

[0080] (3) Extrusion: The ingot is extruded, the extrusion heating temperature is 900°C, the extrusion ratio is 78:1, the extrusion speed is 8 mm / s, and the solid solution treatment is immediately carried out after the extrusion. The temperature of the blank before entering the water is controlled to be 770°C, and the cooling water temperature is <60°C. A φ20 mm extruded blank is obtained.

[0081] (4) Processing: The extruded billet is rolled online once using an 8-roll rolling machine with a processing rate of 84% to obtain a φ8 mm billet.

[0082] (5) Solution treatment: The cold-deformed billet is solution treated to obtain a wire blank. The solution temperature is 710°C and the holding time is 30 minutes. After the wire blank is taken out of the furnace, it is quickly cooled by water.

[0083] (6) Deformation after bottom solution treatment: The blank after bottom solution treatment is subjected to continuous stretching deformation with a processing rate of 86%.

[0084] (7) Heat treatment: The billet after bottom processing and deformation is subjected to aging heat treatment, aging temperature: 420°C, holding time: 440min.

[0085] (8) Finished product stretching: The heat-treated blank is subjected to continuous stretching processing with a processing rate of 93% and a stretching speed of 800 m / min. It is also subjected to online induction annealing heat treatment with an annealing voltage of 42 V to obtain a φ0.8 mm finished product.

[0086] Example 3 This embodiment provides a method for preparing a copper alloy for a connector, and the specific steps are as follows: (1) Melting: Prepare the ingredients according to the composition ratio requirements in Table 1 and place the raw materials into a melting furnace for melting; the melting temperature is 1340°C.

[0087] (2) Casting: The semi-continuous casting process is used to cast ingots. The molten copper is introduced into the crystallizer for continuous casting. The temperature of the molten copper when it flows into the crystallizer is controlled to be 1260°C, and the pulling speed is 40 mm / min. The pulled copper ingots are sawed and surface processed as required to obtain φ250 mm specification ingot blanks.

[0088] (3) Extrusion: The ingot is extruded, the extrusion heating temperature is 930°C, the extrusion ratio is 78:1, the extrusion speed is 5 mm / s, and the solid solution treatment is immediately carried out after the extrusion. The temperature of the blank before entering the water is controlled to be 820°C, and the cooling water temperature is <60°C. A φ20 mm extruded blank is obtained.

[0089] (4) Processing: The extruded billet is rolled online once using an 8-roll rolling machine with a processing rate of 84% to obtain a φ8 mm billet.

[0090] (5) Solution treatment: The cold-deformed billet is solution treated to obtain a wire blank. The solution temperature is 740°C and the holding time is 10 min. After the wire blank is taken out of the furnace, it is quickly cooled by water.

[0091] (6) Deformation by bottoming: The blank after solution treatment is subjected to continuous stretching deformation with a processing rate of 81% to obtain a φ3.5 mm blank.

[0092] (7) Heat treatment: The billet after bottom processing and deformation is subjected to aging heat treatment, aging temperature: 430°C, holding time: 300 min.

[0093] (8) Finished product stretching: The heat-treated blank is subjected to continuous stretching processing with a processing rate of 92% and a stretching speed of 700 m / min. It is also subjected to online induction annealing heat treatment with an annealing voltage of 45 V to obtain a φ1 mm finished product.

[0094] Example 4 This embodiment provides a method for preparing a copper alloy for a connector, and the specific steps are as follows: (1) Melting: Prepare the ingredients according to the composition ratio requirements in Table 1 and place the raw materials into a melting furnace for melting; the melting temperature is 1380°C.

[0095] (2) Casting: The semi-continuous casting process is used to cast ingots. The molten copper is introduced into the crystallizer for continuous casting. The temperature of the molten copper when it flows into the crystallizer is controlled to be 1280°C, and the pulling speed is 30 mm / min. The pulled copper ingots are sawed and surface processed as required to obtain φ150 mm ingot blanks.

[0096] (3) Extrusion: The ingot is extruded, the extrusion heating temperature is 880°C, the extrusion ratio is 67:1, the extrusion speed is 10 mm / s, and the solid solution treatment is immediately carried out after the extrusion. The temperature of the blank before entering the water is controlled to be 800°C, and the cooling water temperature is <60°C. A φ13 mm extruded blank is obtained.

[0097] (4) Processing: The extruded billet is stretched and formed online by a 9-die continuous drawing device with a processing rate of 71% to obtain a φ7 mm billet.

[0098] (5) Solution treatment: The cold-deformed billet is solution treated to obtain a wire blank. The solution temperature is 750°C and the holding time is 5 minutes. After the wire blank is taken out of the furnace, it is quickly cooled by water.

[0099] (6) Deformation by bottoming: The blank after solution treatment is subjected to continuous stretching deformation with a processing rate of 75% to obtain a φ3.5 mm blank.

[0100] (7) Heat treatment: The billet after bottom processing and deformation is subjected to aging heat treatment, aging temperature: 450°C, holding time: 400 min.

[0101] (8) Finished product stretching: The heat-treated blank is continuously stretched at a processing rate of 932% at a stretching speed of 600 m / min, and an online induction annealing heat treatment is performed at an annealing voltage of 45 V to obtain a φ1 mm finished product.

[0102] Example 5 This embodiment provides a method for preparing a copper alloy for a connector, and the specific steps are as follows: (1) Melting: Prepare the ingredients according to the composition ratio requirements in Table 1 and place the raw materials into a melting furnace for melting; the melting temperature is 1400°C.

[0103] (2) Casting: The semi-continuous casting process is used to cast ingots. The molten copper is introduced into the crystallizer for continuous casting. The temperature of the molten copper when it flows into the crystallizer is controlled to be 1280°C, and the pulling speed is 35 mm / min. The pulled copper ingots are sawed and surface processed as required to obtain φ150 mm ingot blanks.

[0104] (3) Extrusion: The ingot is extruded, the extrusion heating temperature is 910°C, the extrusion ratio is 78:1, the extrusion speed is 7 mm / s, and the solid solution treatment is immediately carried out after the extrusion. The temperature of the blank before entering the water is controlled to be 800°C, and the cooling water temperature is <60°C. A φ12 mm extruded blank is obtained.

[0105] (4) Processing: The extruded billet is stretched and formed online by a 9-die continuous drawing device with a processing rate of 75% to obtain a φ6 mm billet.

[0106] (5) Solution treatment: The cold-deformed billet is solution treated to obtain a wire blank. The solution temperature is 760°C and the holding time is 10 min. After the wire blank is taken out of the furnace, it is quickly cooled by water.

[0107] (6) Deformation by processing with bottom retention: The blank after solution treatment is subjected to continuous stretching deformation with a processing rate of 75% to obtain a φ3 mm blank.

[0108] (7) Heat treatment: The billet after bottom processing and deformation is subjected to aging heat treatment, aging temperature: 450°C, holding time: 480min.

[0109] (8) Finished product stretching: The heat-treated blank is subjected to continuous stretching processing with a processing rate of 89%; the stretching speed is 500 m / min, and an online induction annealing heat treatment is performed with an annealing voltage of 50 V to obtain a φ1 mm finished product.

[0110] Example 6 This embodiment provides a method for preparing a copper alloy for a connector, and the specific steps are as follows: (1) Melting: Prepare the ingredients according to the composition ratio requirements in Table 1 and place the raw materials into a melting furnace for melting; the melting temperature is 1400°C.

[0111] (2) Casting: The semi-continuous casting process is used to cast ingots. The molten copper is introduced into the crystallizer for continuous casting. The temperature of the molten copper when it flows into the crystallizer is controlled to be 1300°C, and the pulling speed is 25 mm / min. The pulled copper ingots are sawed and surface processed as required to obtain φ150 mm ingot blanks.

[0112] (3) Extrusion: The ingot is extruded, the extrusion heating temperature is 940°C, the extrusion ratio is 57:1, the extrusion speed is 5 mm / s, and the solid solution treatment is immediately carried out after the extrusion. The temperature of the blank before entering the water is controlled to be 830°C, and the cooling water temperature is <60°C. A φ14 mm extruded blank is obtained.

[0113] (4) Processing: The billet obtained by extrusion is deformed by coiling, and coiled to φ11 specification, and then subjected to softening annealing treatment at 680°C and kept warm for 180 min. The total coiling processing rate is 67%; a φ8 mm billet is obtained.

[0114] (5) Solution treatment: The cold-deformed billet is solution treated to obtain a wire blank. The solution temperature is 780°C and the holding time is 5 minutes. After the wire blank is taken out of the furnace, it is quickly cooled by water cooling.

[0115] (6) Deformation by processing with bottom retention: The blank after solution treatment is subjected to continuous stretching deformation with a processing rate of 86% to obtain a φ3 mm blank.

[0116] (7) Heat treatment: The billet after bottom processing and deformation is subjected to aging heat treatment, aging temperature: 440°C, holding time: 480min.

[0117] (8) Finished product stretching: The heat-treated blank is subjected to continuous stretching processing with a processing rate of 75%; the stretching speed is 700 m / min, and online induction annealing heat treatment is performed with an annealing voltage of 55 V to obtain a φ1.5 mm finished product.

[0118] Comparative Example 1 This comparative example provides a method for preparing a copper alloy, and the specific preparation steps are the same as those in Example 1.

[0119] Comparative Example 2 This comparative example provides a method for preparing a copper alloy. The preparation steps are basically the same as those in Example 1. The difference from Example 1 is that in step (3), solid solution treatment is not performed immediately after extrusion. Instead, a new offline solid solution method is adopted. The offline solid solution temperature is 780° C. and the temperature is kept for 60 minutes.

[0120] Comparative Example 3 This comparative example provides a method for preparing a copper alloy. The preparation steps are basically the same as those of Example 1. The difference from Example 1 is that in step (7), the aging temperature of the heat treatment is 320° C. and the holding time is 180 min.

[0121] Comparative Example 4 This comparative example provides a method for preparing a copper alloy. The preparation steps are basically the same as those of Example 1. The difference from Example 1 is that in step (8), the finished product is not subjected to online induction annealing heat treatment after stretching.

[0122] Comparative Example 5 This comparative example provides an oxygen-free TU2 copper φ1.2 mm thin wire product.

[0123] Comparative Example 6 This comparative example provides a common H65 brass φ1.2mm thin wire product.

[0124] Comparative Example 7 This comparative example provides a common CuSn5 tin phosphor bronze φ1.2mm fine wire product.

[0125] Performance Testing 1. Tensile strength and elongation test: GB / T 228.1-2010 Tensile test of metallic materials Part 1: Room temperature tensile test method.

[0126] 2. Metallographic microscopic test: YS / T 449-2002 Microstructure inspection method for copper and copper alloy castings and processed products.

[0127] 3. Electrical conductivity: GB / T 351-2019 Measurement method of resistivity of metal materials.

[0128] The copper alloys of Examples 1-6 and Comparative Examples 1-7 were subjected to the above performance tests, and the test results are shown in Table 3. The copper alloys of Examples 1-6 and Comparative Examples 1-7 were processed into PIN pins, and their cold heading quality and bending quality were tested. The test results are shown in Table 4.

[0129] Table 3

[0130] Table 4

[0131] It can be seen from the test data in Table 1 and Table 2 that the quantity and size of the strengthening precipitation phase of Comparative Example 1 have no obvious advantages over those of the embodiment, and the strength, high temperature softening resistance and elongation plasticity under the same process conditions are not as good as those of the embodiment. At the same time, the grain size is large, the uniformity of the organization is general, and the cold heading surface quality is not as good as that of the embodiment.

[0132] Comparative Example 2 adds an offline solid solution process after pressing. After the material is heated for the second time, the grains grow. The mechanical properties, high temperature softening resistance and cold heading quality of the material are not as good as those of the embodiment. Figure 3 It can be seen that due to the additional offline solution treatment after extrusion and the different composition design from the embodiment, the grain effect of Comparative Example 2 is poor, and the coarse grains and uneven distribution cause its cold heading effect to be poor.

[0133] The aging treatment effect of comparative example 3 is insufficient, the amount of strengthening phase precipitation is obviously insufficient, the material strength, high temperature softening resistance and plasticity are not as good as those of the embodiment, and cracks appear in the cold heading and bending process. The comprehensive processing effect is not as good as that of the embodiment. Figure 4 It can be seen that due to the low aging treatment temperature, the grain structure did not recrystallize, and the processed structure morphology was retained, which is not conducive to cold heading processing.

[0134] In Comparative Example 4, the finished product was not subjected to induction annealing after stretching, resulting in high material strength and seriously low plasticity. The material was severely cracked during cold heading and bending processing, and the low plasticity caused great loss of cold heading mold.

[0135] Comparative Example 5: Although the oxygen-free copper product on the market has excellent electrical conductivity, its strength and resistance to high-temperature softening are inferior to those of the embodiment.

[0136] Comparative Examples 6 and 7 are common brass and tin-phosphor bronze products on the market. Although the material strength is close to that of the embodiment, their electrical conductivity and resistance to high-temperature softening are inferior to those of the embodiment.

[0137] The present invention can be implemented in various ways and is not limited to the above-mentioned embodiments and / or examples. A person skilled in the art can understand that the present invention can be implemented in other specific ways without changing the technical concept or essential features of the present invention. Therefore, it should be understood that the above-mentioned embodiments and / or examples are exemplary and are not intended to limit the present invention.

Claims

1. A copper alloy for a connector, characterized in that: In terms of mass percentage, the composition of the copper alloy for the connector is: Ni: 2.0-4.0%; Si: 0.4~1.2%; Mg: 0.02~0.3%; Mn: 0.001~0.2%; P: 0.001~0.05%; X: 0~0.2%, the balance is Cu and unavoidable impurities, and the impurities are less than 0.5%; wherein X is one or more of Nb, Zr, and Cr.

2. The copper alloy for connector according to claim 1, characterized in that: The phase structure of the copper alloy for connector includes copper α phase and precipitation strengthening phase, and the precipitation strengthening phase includes one or more of NiSi phase, MnSi phase, NiP phase and CrSi phase.

3. The copper alloy for connector according to claim 1, characterized in that: The average grain size of the copper alloy for the connector is ≤5 μm, the size of the precipitated phase is <200 nm, and the distribution number of the precipitated phase is 1*10 6 ~6*10 6 Pieces / mm 2 , the NiSi phase accounts for more than 90% of the precipitation strengthening phase.

4. The method for preparing the copper alloy for connector according to any one of claims 1 to 3, characterized in that: The specific steps of the preparation method are as follows: Step S1: Melting: Mix the ingredients according to the required composition ratio, and put the raw materials or recycled materials into the melting furnace for melting; Step S2: introducing molten copper into a crystallizer for continuous casting of ingots, controlling the temperature of the molten copper when it flows into the crystallizer to be 1220-1300° C., and sawing and surface processing the pulled copper ingots as required; Step S3: extruding the ingot, the extrusion heating temperature is 850-950°C; and performing a solid solution treatment immediately after the extrusion; Step S4: processing the extruded blank with a processing rate of 50-90%; then subjecting the deformed blank to a solid solution treatment to obtain a wire blank, which is rapidly cooled after being taken out of the furnace; and then processing the cooled wire blank with a processing rate of 60-95%; Step S5: heat-treating the blank processed in step S4, and then continuously stretching the blank with a processing rate of 60-95%; and performing online induction annealing heat treatment to obtain the copper alloy for the connector.

5. The method for preparing the copper alloy for connector according to claim 4, characterized in that: In step S2, the continuous casting method is semi-continuous casting or horizontal continuous casting; And / or, the specific condition of the traction is: the traction speed is 20~60mm / min.

6. The method for preparing the copper alloy for connector according to claim 4, characterized in that: In step S3, the properties of the billet produced by extrusion are as follows: elongation ≥ 30%, electrical conductivity ≤ 25% IACS, and average grain size ≤ 0.2 mm.

7. The method for preparing the copper alloy for connector according to claim 4, characterized in that: In step S3, the specific conditions of the extrusion are: the extrusion heating temperature is 850-950°C, the extrusion ratio is 30-100:1; the extrusion speed is 5-12 mm / s; And / or, in step S3, the conditions of the solution treatment are: controlling the temperature of the blank before entering the water to 700-950°C, and the cooling water temperature to <60°C.

8. The method for preparing the copper alloy for connector according to claim 4, characterized in that: The conditions of the solution treatment in step S4 are: solution temperature: 700-800°C, holding time 2-60 min; and / or the cooling rate of the wire embryo after being taken out of the furnace is greater than 200°C / s.

9. The method for preparing the copper alloy for connector according to claim 4, characterized in that: The heat treatment conditions in step S5 are: aging temperature: 380-500° C., and holding time: 30-600 min.

10. The method for preparing the copper alloy for connector according to claim 4, characterized in that: The processing rate of the continuous stretching process in step S5 is 60-95%; the stretching speed is 300-1000 m / min; And / or, the annealing voltage of the online induction annealing heat treatment is 40-60V.

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