CN113637868B

CN113637868B - Copper alloy capable of being riveted and cut, and preparation method and application thereof

Info

Publication number: CN113637868B
Application number: CN202110906478.0A
Authority: CN
Inventors: 邵海洋; 宋玉波; 徐浩浩; 刘庆; 熊承义; 周文强; 应佳敏; 刘亚丽
Original assignee: Ningbo Powerway Alloy Material Co Ltd
Current assignee: Ningbo Powerway Alloy Material Co Ltd
Priority date: 2021-08-09
Filing date: 2021-08-09
Publication date: 2022-04-26
Anticipated expiration: 2041-08-09
Also published as: CN113637868A

Abstract

The invention discloses a copper alloy capable of being riveted and cut, which comprises the following components in percentage by weight: 59-61% of Cu, 0.005-0.1% of Pb, 0.005-0.15% of X1 element, 0.001-0.05% of X2 element, and the balance of Zn; wherein, the X1 element is one or more than one of Ni, Mn, Fe and Sn elements, and the X2 element is one or more than one of P, Si elements. Compared with the common H62 brass, the copper alloy has the advantages that the cutting processing performance is improved and the cutting efficiency can be improved by more than 30% by controlling the addition of the alloy elements. The copper alloy has the tensile strength of 500-620 MPa, the elongation after fracture of 12-18%, the HV hardness of 140-170, the conductivity of 20-26% IACS, excellent riveting performance, and can be processed into products such as bars, wires, plate strips and the like, and the copper alloy can be widely applied to the fields of electrical plugs, connectors, low-voltage switches and the like due to the characteristics of riveting and cutting processing.

Description

Copper alloy capable of being riveted and cut, and preparation method and application thereof

Technical Field

The invention relates to a copper alloy, in particular to a copper alloy capable of being riveted and cut, a preparation method and application thereof.

Background

The lead brass has very good cutting processing performance, so the lead brass is widely applied to various industries and fields. However, with the rapid development of the times, people have higher and higher requirements on their living environments, and the environmental protection and the green environment have become the inevitable trend of future development.

The early european union RoHS act exempts from lead element in raw materials used in some industries (e.g., processing electrical appliances, medical equipment, toys, entertainment and sports equipment), but does not continue to exempt from lead element after 7/1/2021. Therefore, lead brass in use in some industries will certainly be replaced by lead-free environment-friendly brass in the future. Such as lead pins in the electrical industry, are mostly processed using C3602. The lead content of the product is about 2.2 percent, and the latest RoHS regulation requires that the Pb content is less than 0.1 percent. This means that these industries, if they continue to use C3602 materials, will not comply with the requirements of RoHS legislation. Alternatively, however, the conventional H62 product cannot meet the cutting requirements of customers due to poor machinability, while the H58 product with lower copper content cannot meet the riveting requirements of customers due to relatively poor plasticity.

Based on the above consideration, the invention develops the brass alloy which can not only adapt to the cutting processing of customers, but also meet the riveting requirements of customers, and in addition, the Pb content of the brass alloy can also meet the requirements of the latest RoHS regulation. The alloy is very suitable for being used as an environment-friendly alloy to be popularized in large areas in the industries of cold heading, cutting, drilling, electroplating, riveting, thread rolling, stamping and the like.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a copper alloy capable of being riveted and cut, a preparation method and application thereof aiming at the defects of the prior art, wherein the copper alloy has the advantages of tensile strength of 500-620 MPa, elongation after fracture of 12-18%, HV hardness of 140-170, electric conductivity of 20-26% IACS, excellent riveting performance, cutting efficiency which can be improved by more than 30% compared with that of common H62 brass, and wide application in the fields of electrical plugs, connectors, low-voltage switches and the like.

The technical scheme adopted by the invention for solving the technical problems is as follows: a copper alloy capable of being riveted and cut, which comprises the following components in percentage by weight: 59-61% of Cu, 0.005-0.1% of Pb, 0.005-0.15% of X1 element, 0.001-0.05% of X2 element, and the balance of Zn; wherein, the X1 element is one or more than one of Ni, Mn, Fe and Sn elements, and the X2 element is one or more than one of P, Si elements.

The copper alloy of the present invention is a brass alloy. The copper alloy of the invention is added with 0.005-0.1% of Pb element. Pb exists as a free-cutting element in the copper alloy, plays a role of chip breaking in the cutting process, and effectively improves the cutting processability and the cutting efficiency of products. However, since Pb is a great hazard to the environment and human body and is being restricted by more and more industries, the content of Pb in the copper alloy of the present invention is controlled to be less than 0.1%, but if the content of Pb is controlled to be less than 0.005%, the application requirements of the customer in cutting and machining cannot be satisfied. Therefore, the Pb content in the copper alloy is controlled to be 0.005-0.1 percent in comprehensive consideration.

The copper alloy of the invention is added with 0.005-0.15% of X1 element, and the X1 element is one or more of Ni, Mn, Fe and Sn elements. Ni, Mn, Fe and Sn are important strengthening elements in the copper alloy, and the addition of trace Ni, Mn, Fe and Sn elements can obviously improve the strength and hardness of the copper alloy, thereby effectively prolonging the service life of the copper alloy product. The Ni and Sn elements can also improve the corrosion resistance of the copper alloy, thereby improving the reliability of the copper alloy product in moist and corrosive media. If the content of at least one of the elements Ni, Mn, Fe, and Sn is less than 0.005%, the above-mentioned characteristics cannot be exhibited, but if the content of Ni and Sn is increased, the raw material cost of the copper alloy increases, which is not favorable for large-area spread of the copper alloy product, and the excessive amount of Fe and Mn deteriorates the workability of the copper alloy. In the copper alloy, the content of at least one of Ni, Mn, Fe and Sn is controlled to be 0.005-0.15 wt%.

The copper alloy of the invention is added with 0.001-0.05% of X2 element, and the X2 element is one or more than one of P, Si elements. The zinc equivalent coefficient of the Si element in the brass is 10, and the brass has better solid solution strengthening and work hardening effects. Si and P are excellent degasifier and deoxidizer for copper alloy. The P element can be dissolved in the copper matrix in a small amount to play a role in solid solution strengthening. However, excessive Si and P in the copper matrix easily cause the reduction of the conductivity of the alloy, and influence the electrical performance of the electrical brass product. Therefore, the actual control range of the content of at least one of the P, Si elements in the copper alloy of the present invention is 0.001 to 0.05%.

The average grain size of the copper alloy is 5-15 μm. The finer the crystal grain is, the more beneficial the improvement of the alloy yield strength is, and meanwhile, the alloy product has better mobility due to the crystal grain in the riveting process, more uniform deformation and less risk of riveting cracking. However, if the crystal grains are too fine, the stress relaxation resistance of the alloy product is easily reduced, and the service performance of the electrical plug product is affected.

The standard deviation sigma of the grain size of the copper alloy is less than or equal to 3 mu m. When the grain size meets the condition, the grain size distribution is more uniform, the stress concentration can be obviously reduced, and the riveting performance is more favorably improved. Preferably, σ ≦ 2 μm.

The number of Pb particles per unit area of the copper alloy of the present invention is (2 to 100). times.10³Per mm²And the size of the Pb particles is within 200 nm. The size and distribution of Pb can ensure the cutting efficiency of the alloy in the cutting process, and the nano-scale Pb particles are uniformly distributed in the copper matrix and have unit area (mm)²) The number of Pb particles in the lead-free solder paste is (2-100). times.10³Per mm²During the process, on one hand, the effect of further improving the cutting efficiency can be achieved, on the other hand, the rheological uniformity of the alloy in the pressure machining process can be improved, and further the riveting cracking phenomenon of the part after the cutting machining is effectively avoided.

In the microstructure on the copper alloy section, the area percentage of the beta phase is 15-30%, and the beta phase is distributed in an island shape. The beta phase in the brass alloy is more brittle than the alpha phase at normal temperature, and can play a role in assisting chip breaking in the cutting process. Therefore, the copper alloy of the invention can ensure a certain content of beta phase proportion, and can improve the cutting efficiency of the alloy. In addition, the distribution state and morphology of the beta phase also influence the processing characteristics and application performance of the alloy. Such as: when the beta phase is uniformly distributed on the alpha phase matrix, the rheological uniformity of the alloy in the pressure processing process can be improved, and the processing cracking tendency caused by inconsistent tissue rheological is reduced; compared with beta phases distributed in a chain shape, the beta phases distributed in an island shape can block a diffusion channel of zinc atoms in the copper alloy, and the corrosion resistance of the alloy is improved; in addition, when the beta phase is uniformly distributed, the microhardness fluctuation caused by different alpha phase and beta phase hardness in a microscale range can be reduced, the stress uniformity of the cutting tool in the machining process is improved, and the service life of the cutting tool is further prolonged.

The copper alloy achieves the aims of improving the alloy cutting processing performance and meeting the product riveting characteristics by controlling the component content and the morphological characteristics of Pb and beta phases. When the copper alloy is used for cutting and processing electrical plugs, compared with H62 brass, the cutting efficiency can be improved by more than 30%, and riveting is not cracked.

The copper alloy has the tensile strength of 500-620 MPa, the elongation after fracture of 12-18%, the HV hardness of 140-170, the conductivity of 20-26% IACS, excellent riveting performance, machinability and no cracking during riveting.

The preparation method of the copper alloy capable of being riveted and cut comprises the following steps: continuous casting → stretch cogging → primary annealing → cold working → secondary annealing → finished product stretching, wherein the temperature of the primary annealing is 500-650 ℃, and the heat preservation time is 60-300 min; the temperature of the secondary annealing is 400-550 ℃, and the heat preservation time is 30-200 min. The main process comprises the following steps:

1) continuous casting: the casting temperature is 950-1050 ℃, and the casting speed is 1000-1800 mm/min. The control level of the components of the casting blank, the surface quality and the uniformity of the internal structure have important influence on the smooth processing of the alloy to a finished product and the performance of the finished product. In the continuous casting process, parameters such as casting temperature, casting speed and the like are the key control points. The casting temperature is too low or the casting speed is too high, the fluidity of the copper liquid is poor, the micro-structure of the product is uneven, obvious crystal spots appear on the surface of the product, and the cracking and breaking conditions can appear in severe cases. If the casting temperature is too high, the oxidation burning loss of Zn element is accelerated, and the situation of oxidation of the surface of the casting blank or coarse internal structure is generated; if the casting speed is reduced, the casting productivity is reduced, and the manufacturing cost of the product is increased. The casting temperature in the copper alloy continuous casting process is controlled to be 950-1050 ℃, and the casting speed is controlled to be 1000-1800 mm/min, so that the control condition of the component uniformity of the casting blank, the surface and internal structure of the casting blank, the production cost and the subsequent processing problems are integrated.

2) Stretching and cogging: in order to fully eliminate the columnar crystal structure of a casting blank, the processing rate of stretching and cogging should be as large as possible, but the larger the processing rate of stretching and cogging is, the better the processing rate is, the too large processing rate can reduce the plasticity of the material, and further cause the problem of stretching and wire breaking, and the processing rate of stretching and cogging the copper alloy is controlled between 50% and 70%.

3) And (3) graded annealing: the copper alloy adopts a graded annealing process to obtain a specific microstructure appearance. The material is first subjected to an appropriate primary annealing treatment after stretch-cogging. After the primary annealing, cold working is performed at a cold working ratio of 30 to 60%, and then an appropriate secondary annealing treatment is performed. The primary annealing temperature is 500-650 ℃, the heat preservation time is 60-300 min, if the annealing temperature is lower than 500 ℃ or the heat preservation time is less than 60 min, the processed deformed structure is difficult to be fully eliminated, and beta phases of the deformed structure are always distributed in a chain shape, which is not beneficial to the application characteristics of the alloy; if the annealing temperature is higher than 650 ℃ or the holding time exceeds 300 minutes, the crystal grains are too large, and the distribution of beta phase is not uniform. The cold working rate of 30-60% is beneficial to redistribution of crystal grains and improvement of uniformity of crystal grain sizes. Then, the temperature is kept at 400-550 ℃ for 30-200 min for secondary annealing to obtain uniform grain structure, the standard deviation sigma of the grain size is controlled to be not more than 3 mu m, the average grain size is within the range of 5-15 mu m, and the number of Pb particles in unit area is (2-100) multiplied by 10³Per mm²And the size of Pb particles is controlled within 200nm, and the beta phase is distributed in an island shape.

4) And (3) finished product stretching: and (3) stretching the finished product at a finished product stretching rate of 10-40% to obtain a smooth material surface and a specific microstructure and performance. Because the copper alloy of the invention needs to be prepared into a final electrical product by various processing means such as cutting, drilling, riveting, injection molding and the like, the performance requirements of the copper alloy of the invention are complex, and the copper alloy not only needs specific tensile strength, elongation after fracture, hardness and conductivity, but also needs uniformity on a microstructure. The size and distribution of grains, the size and density of Pb particles, the appearance and distribution of beta phases and the like can be effectively controlled by combining the heat treatment process of graded annealing, the control of cold working rate and the control of finished product elongation rate, and finally the tensile strength of the copper alloy is controlled to be 500-620 MPa, the elongation after fracture is controlled to be 12-18%, the HV hardness is controlled to be 140-170, the conductivity is controlled to be 20-26% IACS, and the copper alloy has excellent riveting performance.

The copper alloy capable of being riveted and cut can be applied to the fields of electrical plugs, connectors, low-voltage switches and the like.

Compared with the prior art, the invention has the beneficial effects that:

(1) compared with the common H62 brass, the copper alloy has the advantages that the cutting processing performance is improved and the cutting efficiency can be improved by more than 30% by controlling the addition of the alloy elements.

(2) The copper alloy has the tensile strength of 500-620 MPa, the elongation after fracture of 12-18%, the HV hardness of 140-170, the conductivity of 20-26% IACS, and excellent riveting performance.

(3) The copper alloy can be processed into products such as bars, wires, plate strips and the like, and is widely applied to the fields of electrical plugs, connectors, low-voltage switches and the like due to the characteristics of riveting and cutting processing.

Drawings

FIG. 1 is a metallographic microstructure micrograph of a cross section of a copper alloy according to example 7.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

The copper alloy components in the embodiments 1-16 of the invention listed in table 1 are proportioned, and the raw materials are fully old materials or a way of matching new materials with old materials in a certain proportion. Carrying out component assay after smelting, and carrying out component assay according to component assay resultPerforming dilution or compensation, introducing the copper liquid into a heat preservation furnace after the components are qualified, and casting by an upward introduction mode, wherein the specification of the casting blank is

The casting temperature is 950-1050 ℃, and the drawing speed is 1000-1800 mm/min. Stretching and cogging by adopting a single-pass interval stretching or multi-mode continuous stretching mode to

Then annealing heat treatment is carried out, more than two times of stretching and annealing treatment can be carried out according to the specification requirement of a finished product, wherein the processing rate of stretching and cogging is controlled to be 30-70%, the temperature of primary annealing is 500-650 ℃, and the heat preservation time is 60-300 min; the temperature of the secondary annealing is 400-550 ℃, and the heat preservation time is 30-200 min. The annealing process is preferably bright annealing with protective gas, or aerobic annealing combined with acid cleaning, and final product stretching with the specification of the finished product

2 comparative examples of ordinary H58 and H62 brass

Wire samples.

The copper alloy of each embodiment and comparative example is tested according to the method specified by related national and industrial standards

The tensile strength, elongation after break, hardness and conductivity of the wire samples were measured and the results are shown in Table 2.

Tensile test at room temperature according to GB/T228.1-2010 Metal Material tensile test part 1: room temperature test method is carried out on an electronic universal mechanical property tester.

Conductivity test according to GB/T3048-2007 electric wire and cable electric performance test method part 2: resistivity test of metallic material, expressed in% IACS.

Observing and counting the grain size through an optical microscope, and calculating the average value of the grain size; the standard deviation σ value of the grain size was statistically calculated using the EBSD module.

The cutting machining performance and the cutting efficiency are evaluated by adopting a drilling test method, and under the same drilling condition, the method adopts

The drill bit drills holes, the machining number per minute of each copper alloy sample of the embodiment and the comparative example is measured, and the larger the drilling number in the same time, the better the cutting machining performance is, and the higher the cutting efficiency is.

And (3) carrying out flattening test after drilling, flattening the drilling sample by using pressure equipment, and observing whether the sample is cracked or not and the cracking degree after flattening, thereby judging the quality of the riveting performance of the copper alloy.

FIG. 1 is a metallographic microstructure micrograph of a cross section of a copper alloy according to example 7. It is obvious from the figure that the beta phase is distributed in an island shape, and the Pb particles of nanometer level are uniformly distributed in the copper matrix.

The detection finds that the copper alloy disclosed by the invention realizes the following performances: the average grain size is 5-15 μm, the standard deviation sigma value of the grain size is within 3 μm, the area ratio of beta phase is 15-30%, the tensile strength is 500-620 MPa, the elongation after fracture is 12-18%, the HV hardness is 140-170, the electric conductivity is 20-26% IACS, and the cutting processing and riveting can be carried out. In addition, compared with the comparative alloy, the specific preparation method provided by the invention has the advantages that the specific preparation method is adopted, the grain size, the Pb and beta phase component content, the morphology distribution and the like are reasonably controlled, the performance of the brass alloy is better than that of the common H58 and H62 brass alloys, the riveting performance is obviously improved compared with H58, the cutting machining performance is obviously improved compared with H62, and the cutting efficiency is improved by more than 30%.

The compositions and performance test results of the example and comparative alloys are shown in tables 1 and 2, respectively.

Table 1: composition (wt%) of alloy of examples and comparative examples

Claims

1. A copper alloy capable of being riveted and cut is characterized by comprising the following components in percentage by weight: 59-61% of Cu, 0.005-0.1% of Pb, 0.005-0.15% of X1 element, 0.001-0.05% of X2 element, and the balance of Zn; wherein, the X1 element is one or more than one of Ni, Mn, Fe and Sn elements, and the X2 element is one or more than one of P, Si elements; the preparation method of the copper alloy comprises the following steps: continuous casting → stretch cogging → primary annealing → cold working → secondary annealing → finished product stretching, wherein the temperature of the primary annealing is 500-650 ℃, and the heat preservation time is 60-300 min; the temperature of the secondary annealing is 400-550 ℃, and the heat preservation time is 30-200 min.

2. The copper alloy as claimed in claim 1, wherein the average grain size of the copper alloy is 5 to 15 μm.

3. A copper alloy according to claim 2, wherein the standard deviation σ of the grain size of the copper alloy is 3 μm or less.

4. The copper alloy as claimed in claim 1, wherein the number of Pb particles per unit area of the copper alloy is (2-100). times.10³Per mm²And the size of the Pb particles is within 200 nm.

5. The copper alloy according to claim 1, wherein the microstructure of the copper alloy cross section has a beta phase area ratio of 15 to 30%, and the beta phase is distributed in an isolated island form.

6. The copper alloy of claim 1, wherein the cutting efficiency of the copper alloy is improved by more than 30% compared to H62 brass.

7. The copper alloy according to claim 1, wherein the copper alloy has a tensile strength of 500 to 620MPa, an elongation after fracture of 12 to 18%, an HV hardness of 140 to 170, an electric conductivity of 20 to 26% IACS, and an excellent caulking property.

8. The copper alloy according to claim 1, wherein the copper alloy is produced by drawing and cogging at a working ratio of 50 to 70%, the cold working ratio after primary annealing is 30 to 60%, and the final product is produced at a drawing ratio of 10 to 40%.

9. Use of the copper alloy of any one of claims 1 to 7 in the field of electrical plugs, connectors and low-voltage switches.