CN113981269B

CN113981269B - Brass alloy and preparation method thereof

Info

Publication number: CN113981269B
Application number: CN202111267466.4A
Authority: CN
Inventors: 郑恩奇; 叶东皇; 傅杰
Original assignee: Ningbo Jintian Copper Group Co Ltd
Current assignee: Ningbo Jintian Copper Group Co Ltd
Priority date: 2021-10-29
Filing date: 2021-10-29
Publication date: 2022-10-04
Anticipated expiration: 2041-10-29
Also published as: CN113981269A

Abstract

The invention discloses a brass alloy and a preparation method thereof, which are characterized in that: the brass comprises the following components in percentage by mass: 61-65 wt%, pb: < 0.1wt%, in:0.1 to 1.0wt%, sn:0.2 to 0.5wt%, ni:0.1 to 0.5wt%, and the balance of Zn and inevitable impurities. The brass alloy of the invention adopts low tin, the content of tin is 0.2-0.5 wt%, compared with high tin brass, the content of gamma hard phase In the matrix is reduced, the cutter damage condition during turning is reduced, a certain amount of In element is added, the In is similar to Pb, bi and other elements have certain easy cutting ability, and can be combined with Sn element to form gamma-In low melting point brittle phase under a certain condition, the gamma-In low melting point brittle phase is dispersed and distributed on the alpha and beta phase boundary, heat is generated during material cutting, and the gamma-In phase is melted under the heat to play a role of cutting, therefore, the problem of insufficient hard phase generated by low Sn is made up, and the cutting is more facilitated, so that the integral cutting performance of the material is improved.

Description

Brass alloy and preparation method thereof

Technical Field

The invention belongs to the technical field of copper alloys, and particularly relates to a brass alloy and a preparation method thereof.

Background

The brass alloy has good cold and hot processing performance and low use cost, so that the electric appliance plug on the market is prepared by processing brass materials. Taking a fillet plug as an example, the production is mostly processed by a mode of high-speed turning, drilling → electroplating, and the material is required to have good cutting processing performance, cold riveting performance, straightness, electroplating performance and electric conductivity. Brass alloy designations H62 and C3602 are currently commonly used. Among them, lead brass represented by C3602 has good cutting performance, but with the increase of human health consciousness, lead-free brass inevitably becomes a future development trend. The H62 material is low in lead, environment-friendly and good in cold riveting performance, but has poor cutting performance, and cannot be processed and prepared on a large scale by using a high-speed lathe. Other lead-free materials include bismuth-containing brass, silicon brass, tin brass, and the like. The cutting performance of the bismuth-containing brass is close to that of lead brass, but the material has obvious self-cracking tendency, the specification of a common fillet plug is less than phi 5mm, the cold riveting performance of the material after drilling cannot meet the use requirement, the electroplating performance is common, and waste materials are not easy to recycle, so that a plurality of limitations exist. The silicon-containing lead-free brass has the advantages of common cutting performance, poor electroplating performance and easy shedding of a plating layer, and the silicon brass is commonly used for preparing large-specification bars for hot forging. The tin (the tin content is about 0.8wt percent) lead-free brass has good dezincification corrosion resistance, the brass has a large amount of gamma hard phases due to the internal structure, the tool is easy to damage during turning, the hardness can reach more than HV180 when the brass is generally processed to the specification of phi below 5mm, and the cold riveting performance of the material is poor.

The lead-free brass developed and applied in the current market has a plurality of problems, and in order to meet the future market demand, a brass alloy meeting the requirements of bar processing below phi 5mm and having good cutting performance, cold riveting performance, electroplating performance and electric conductivity needs to be developed urgently.

Disclosure of Invention

The invention aims to solve the first technical problem of providing an environment-friendly brass alloy with good cutting performance, cold riveting performance, electroplating performance and electric conductivity.

The technical scheme adopted by the invention for solving the first technical problem is as follows: a brass alloy and a preparation method thereof are characterized in that: the brass comprises the following components in percentage by mass: 61-65 wt%, pb: < 0.1wt%, in:0.1 to 1.0wt%, sn:0.2 to 0.5wt%, ni:0.1 to 0.5wt%, and the balance of Zn and inevitable impurities.

Preferably, the microstructure of the brass contains an α phase, a trace β phase, and a γ -In phase, wherein the α phase is 85 to 95% by area and the γ -In phase is 4 to 10% by area. The lower limit of the gamma-In phase is controlled to be 4%, the material is guaranteed to have good cutting performance, the upper limit of the gamma-In phase is controlled to be 10%, and the situation that the brittleness of the material is increased, and the cold riveting performance and the cold machining performance of a finished product are affected is avoided.

Preferably, the average size of the gamma-In phase is less than or equal to 5 μm, and the average size of the alpha phase is less than or equal to 10 μm. The size is controlled, so that the gamma-In phase is dispersed and distributed, the large-area aggregation of the gamma-In phase is avoided, and the cold riveting performance of the material is reduced. Meanwhile, the control of the alpha-phase grain size is beneficial to forming more gamma-In phase particles distributed In the grain boundary, thereby improving the cutting performance of the material

Preferably, the alloy also comprises at least one of La, ce, mg, mn and Zr, and the total amount is 0.01-0.2 wt%.

Other trace beneficial elements such as La and Ce are added, so that the crystal grains are favorably refined, the impurity removal and purification effects are achieved, and the inclusion weakening of crystal boundaries is reduced. The Mg and Mn elements are added, so that the deoxidizing and reducing effects are mainly achieved in the smelting process, and a proper amount of Mg element is beneficial to improving the cutting performance of the material. The proper amount of Mn element is beneficial to improving the wear resistance of the material and reducing the resistance of the fillet plug in the plugging and unplugging process, thereby improving the deformation resistance. And a proper amount of Zr element is added, so that the high-temperature softening resistance of the material can be improved, and the service life of the round-corner plug is indirectly prolonged.

Preferably, the brass has a tensile strength of 500 to 550MPa, a hardness HV5 of 140 to 170, an elongation of 5 to 18%, and an electric conductivity of not less than 27% IACS.

Preferably, the brass has a cutting rate of 80% or more of C3600, a compression ratio at the time of cold rivet cracking of 80% or more, and a surface roughness Ra of 1 μm or less after turning.

The second technical problem to be solved by the invention is a preparation method of the brass alloy.

The technical scheme adopted by the invention for solving the second technical problem is as follows: a preparation method of a brass alloy is characterized by comprising the following steps: the preparation method comprises the following preparation steps:

1) Smelting: mixing the materials according to the required components, and controlling the smelting temperature to be 950-1000 ℃;

2) Casting: horizontal continuous casting is adopted, wherein the drawing pitch: 35-40 mm; reverse thrust pitch: 1-3 mm; traction speed: 10-20 mm/s; the reverse thrust speed is 1-3 mm/s;

3) Extruding: the extrusion temperature is 650-750 ℃, the ingot casting extrusion ratio is 350-600: 1; extruding the cast ingot to obtain a blank;

4) Coiling: controlling the machining rate of the blank to be 40-65% to obtain a wire blank;

5) Annealing: the annealing temperature is 300-420 ℃, and the heating time is 60-150 min.

6) Combined drawing: and (3) placing the wire blank in a combined drawing machine for drawing, wherein the drawing speed is 40-80 m/min, and the processing rate is controlled at 8-20%.

The quality of the cast ingot indirectly affects the quality of the finished product, the traction pitch, the reverse thrust pitch, the traction speed and the reverse thrust speed are controlled, the columnar crystal grains can be eliminated to a certain degree, the equiaxed crystal grain area is enlarged, the equiaxed crystal grain area accounts for 60-90%, and the average crystal grain size is in the range of 0.1-0.5 mm. The small grain size is controlled to ensure that the In element is distributed more uniformly and dispersedly, and the cutting performance is improved to a certain extent.

The extrusion ratio is controlled to be 350-600, and the extrusion temperature range is 650-750 ℃. The larger extrusion ratio is favorable for controlling the grain size of the alpha phase of the extrusion structure to be 10-30 mu m, the reasonable extrusion temperature is favorable for normal extrusion discharging of the wire blank, and simultaneously, the alpha phase ratio is controlled to be 75-90 percent, so that the plasticity and the processing performance of the material are improved.

The machining rate of the disc drawing process is controlled to be 40-65%, the relatively high machining rate is beneficial to crushing crystal grains, a good fine crystal effect is achieved, and the average size of the obtained alpha-phase crystal grains is 5-20 mu m.

The annealing temperature is set at 300-420 ℃, the beta phase ratio of the structure is reduced, and the alpha phase ratio is increased to 85-98%. The plasticity of the material is improved, and the cold riveting performance of the material is improved.

The processing rate of the combined drawing process is controlled to be 8-20%. The relatively low processing rate can control the hardness of the finished product to be in the range of 140-170 HV, and the elongation is 5-18%. On one hand, the hardness of the finished bar is effectively controlled, the cold riveting performance of the material can be guaranteed to meet the use requirement, meanwhile, the finished bar is not required to be annealed at low temperature subsequently, the straightness of the finished bar is guaranteed to be good, the high-speed machining requirement of a lathe is met, and deformation and bending caused by annealing softening are avoided.

Preferably, in the step 3), the ingot is heated before extrusion, the heating process is carried out in three stages, and the preheating stage is as follows: the temperature is controlled between 200 and 300 ℃, and the heating time is 20 to 30min; a heating stage: the temperature is controlled to be 400-600 ℃, and the heating time is 10-30 min; and (3) a heat preservation stage: 650-750 ℃ and heating time of 10-30 min.

The extrusion heating is carried out in three stages, the first stage mainly plays a role in ingot preheating, and the temperature is controlled to be 200-300 ℃. Compared with the traditional mode of directly heating to high temperature, the method can maintain the original structure appearance and size as much as possible and avoid crystal grain growth caused by overheating. The second stage plays a role in temperature rise transition, if the temperature is set to be too high, the temperature of the cast ingot is too fast, the temperature of the inner layer and the outer layer of the cast ingot is inconsistent (the surface is high, the core part is low), and the uniformity of the structure is reduced. If the temperature is set to be too low, the temperature is heated to the third stage, and the temperature rise range is too large, so that the ingot discharging temperature is not easy to accurately control. Therefore, the temperature of the second stage is controlled to be 400-600 ℃, the temperature of the core part of the ingot is kept consistent with the surface temperature, and the temperature deviation of the ingot after discharging is indirectly and effectively controlled to be within 5-15 ℃. The third stage mainly plays a role in ingot heat preservation, and the heating temperature of the ingot is controlled within a set extrusion temperature range.

Preferably, in the step 5), the annealing process is performed in two stages, and the preheating stage: controlling the temperature at 150-250 ℃ and raising the temperature for 5-20 min; and (3) a heat preservation stage: the temperature is controlled at 300-420 ℃, and the heating time is 60-150 min.

The annealing process adopts step annealing, the annealing temperature of the first stage is set to be 150-250 ℃, and because the previous-stage stretching processing rate is high, the material begins to recover in a dislocation way and has a recrystallization trend, and the internal organization structure basically does not change. The annealing temperature of the second stage is set at 300-420 ℃, the beta phase ratio of the structure is reduced, and the alpha phase ratio is increased to 85-98%. The plasticity of the material is improved, and the cold riveting performance of the material is improved. Meanwhile, the grain size of the structure is basically unchanged after the first-stage low-temperature recovery annealing, and the average grain size of alpha-phase grains is increased by less than 5 mu m.

Compared with the prior art, the invention has the advantages that:

1) The brass alloy of the invention adopts low tin, the content of tin is 0.2-0.5 wt%, compared with high-tin brass, the content of gamma hard phase In the matrix is reduced, the cutter damage condition during turning is reduced, a certain amount of In element is added, the In is similar to Pb, the Bi and other elements have certain easy cutting ability, and can be combined with the Sn element to form gamma-In low-melting-point brittle phase under a certain condition, the gamma-In low-melting-point brittle phase is dispersed and distributed on the boundary of alpha and beta phases, heat is generated during material cutting, and the gamma-In phase is melted under the heat to play a role of cutting, so that the problem of insufficient hard phase generated by low Sn is made up, and the cutting is facilitated, and the integral machinability of the material is improved; in addition, the content of the gamma hard phase is reduced, the plasticity of the material is increased, and the riveting performance of the material is improved; meanwhile, the In element can increase the critical current density of the material, thereby improving the conductivity.

2) The brass alloy of the present invention has a tensile strength of 500 to 550MPa, a hardness HV5 of 140 to 170, an elongation of 5 to 18%, an electric conductivity of not less than 27% IACS; the cutting rate is more than 80% of C3600, the compression ratio is more than 80% when the cold riveting cracks, and after turning, the surface roughness Ra of the brass is less than 1 mu m, so that the brass has good cutting, wear-resisting, conductive and electroplating performances, and meets the requirements of processing and using fillet plugs.

Drawings

FIG. 1 shows the morphology of the turning chips of example 1 of the present invention.

FIG. 2 shows the morphology of the turning chips of the comparative example of the present invention.

Detailed Description

The invention is described in further detail below with reference to the following examples of the drawings.

The invention provides 4 examples and 1 comparative example, the specific components are shown in table 1.

Example 1

1) Smelting: the raw materials include electrolytic plate, indium ingot, tin ingot, pure nickel, zinc ingot and lanthanum-cerium alloy. The raw materials are sequentially added into a power frequency furnace to be heated, and the smelting temperature is controlled at 990 ℃.

2) Casting: producing an ingot by adopting a horizontal continuous casting process, wherein the traction pitch is as follows: 35mm; reverse thrust pitch: 2mm; traction speed: 12mm/s; the reverse thrust speed is 2mm/s. The specification of the cast ingot is as follows: phi 145mm.

3) Extruding: heating the cast ingot before extrusion, wherein the heating process is carried out in three stages. A preheating stage: controlling the temperature at 300 ℃, and heating for 25min; a heating stage: controlling the temperature at 600 ℃, and heating for 30min; and (3) a heat preservation stage: heating at 710 deg.C for 30min. An 1800t extruder was used to extrude a billet having a gauge of 8 mm.

4) Coiling: and (3) after pickling, the blank is stretched by using an inverted disc drawing machine, and the processing rate is 60%. The specification of the wire blank after stretching is phi 5mm

5) Annealing: annealing the stretched wire blank in a pit furnace, wherein the annealing process is carried out in two stages: controlling the temperature at 150 ℃, and raising the temperature for 15min; and (3) a heat preservation stage: the temperature is controlled at 380 ℃ and the heating time is 120min.

6) And (3) combined drawing: the blank is placed in a 2T combined drawing machine for drawing. The drawing rate is 60m/min, the processing rate is 9 percent, and the specification of a finished product is phi 4.77mm.

7) Straightening and sizing: and (5) straightening, sizing, packaging and warehousing the finished bar.

Example 2

1) Smelting: the raw materials used include electrolytic plate, indium ingot, tin ingot, pure nickel, zinc ingot and metal magnesium. The raw materials are sequentially added into a power frequency furnace to be heated, and the smelting temperature is controlled at 980 ℃.

2) Casting: producing an ingot by adopting a horizontal continuous casting process, wherein the traction pitch is as follows: 36mm; reverse pitch: 2mm; traction speed: 14mm/s; the reverse thrust speed is 2mm/s. The specification of the cast ingot is as follows: phi 145mm.

3) Extruding: heating the cast ingot before extrusion, wherein the heating process is carried out in three stages. A preheating stage: controlling the temperature at 280 ℃, and heating for 25min; a heating stage: controlling the temperature at 580 deg.C, and heating for 30min; and (3) a heat preservation stage: heating at 680 deg.C for 20min. An 1800t extruder was used to extrude a 7.5mm diameter billet.

4) Coiling: and (3) after pickling, stretching the blank by using an inverted disc drawing machine, wherein the processing rate is 52%. The specification of the wire blank after stretching is phi 5.2mm

5) Annealing: annealing the stretched wire blank in a pit furnace, wherein the annealing process is carried out in two stages: controlling the temperature at 160 ℃, and raising the temperature for 20min; and (3) a heat preservation stage: the temperature is controlled at 400 ℃ and the heating time is 90min.

6) And (3) combined drawing: the blank is placed in a 2T combined drawing machine for drawing. The drawing rate is 50m/min, the processing rate is 16 percent, and the specification of a finished product is phi 4.77mm.

Example 3

1) Smelting: the raw materials comprise an electrolytic plate, an indium ingot, a tin ingot, pure nickel, a zinc ingot, metal manganese and copper-zirconium alloy according to the required component proportion. The raw materials are sequentially added into a power frequency furnace to be heated, and the melting temperature is controlled to be 1000 ℃.

2) Casting: producing an ingot by adopting a horizontal continuous casting process, wherein the traction pitch is as follows: 38mm; reverse pitch: 2mm; traction speed: 12mm/s; the reverse thrust speed is 2mm/s. The specification of the cast ingot is as follows: phi 145mm.

3) Extruding: heating the cast ingot before extrusion, wherein the heating process is carried out in three stages. A preheating stage: controlling the temperature at 300 ℃, and heating for 30min; a heating stage: controlling the temperature at 580 deg.C, and heating for 20min; and (3) a heat preservation stage: heating at 680 deg.C for 25min. An 1800t extruder was used to extrude a 7.8mm diameter billet.

4) Coiling: and (3) after pickling, the blank is stretched by using an inverted disc drawing machine, and the processing rate is controlled at 54%. The specification of the wire blank after stretching is phi 5.3mm

5) Annealing: annealing the stretched wire blank in a pit furnace, wherein the annealing process is carried out in two stages: controlling the temperature at 180 ℃ and raising the temperature for 12min; and (3) a heat preservation stage: the temperature is controlled at 360 deg.C, and the heating time is 150min.

6) Combined drawing: and (3) placing the blank in a 2T combined drawing machine for drawing. The drawing speed is 50m/min, the processing rate is controlled at 19 percent, and the specification of a finished product is phi 4.77mm.

Example 4

1) Smelting: the raw materials include electrolytic plate, indium ingot, tin ingot, pure nickel and zinc ingot. The raw materials are sequentially added into a power frequency furnace to be heated, and the smelting temperature is controlled at 990 ℃.

2) Casting: and (3) producing an ingot casting by using an electromagnetic stirring device in an auxiliary manner and adopting a horizontal continuous casting process, wherein the traction pitch is as follows: 35mm; reverse pitch: 2mm; traction speed: 12mm/s; the reverse thrust speed is 2mm/s. The specification of the cast ingot is as follows: phi 145mm.

3) Extruding: heating the cast ingot before extrusion, wherein the heating process is carried out in three stages. A preheating stage: controlling the temperature at 300 ℃, and heating for 30min; a heating stage: controlling the temperature at 600 ℃, and heating for 30min; and (3) a heat preservation stage: heating at 700 deg.C for 20min. An 1800t extruder was used to extrude a billet having a gauge of 8 mm.

4) Coiling: and (3) after pickling, stretching the blank by using an inverted disc drawing machine, wherein the processing rate is 61%. The specification of the wire blank after stretching is phi 5.0mm

5) Annealing: annealing the stretched wire blank in a pit furnace, wherein the annealing process is carried out in two stages: controlling the temperature at 220 ℃, and raising the temperature for 16min; and (3) a heat preservation stage: the temperature is controlled at 390 ℃, and the heating time is 120min.

Comparative example

1) Smelting: the raw materials comprise brass scraps, red copper scraps, brass tinning scraps, brass nickel plating scraps, copper-iron intermediate alloy, metal silicon and copper-phosphorus alloy according to the required component proportion. The raw materials are sequentially added into a power frequency furnace to be heated, and the smelting temperature is 1020 ℃.

2) Casting: adopting semi-continuous casting process, the casting temperature is 1000 ℃. The specification of the obtained cast ingot is as follows: phi 145mm.

3) Extruding: a1800 t extruder was used to extrude billets of 6.4mm gauge. The extrusion temperature was 600 ℃.

4) Homogenizing and annealing: and (3) carrying out homogenization annealing on the extrusion blank, wherein the annealing temperature is 500 ℃, and the heat preservation time is 3h.

5) Coiling: and (3) after pickling, the blank is stretched by using an inverted disc drawing machine, and the processing rate is 31%. The specification of the wire blank after stretching is phi 5.3mm.

6) Annealing: and softening and annealing the wire blank at 400 ℃, heating for 30min, and keeping the temperature for 240min.

7) And (3) finished product stretching: and (4) after pickling, stretching the blank by using a 2T combined drawing machine. The drawing rate is 50m/min, the processing rate is 20 percent, and the specification of a finished product is phi 4.77mm.

8) Straightening and sizing: and (5) straightening, sizing, packaging and warehousing the finished bar.

The obtained examples and comparative examples are subjected to relevant tests, and are specifically shown in tables 2 and 3.

And (3) mechanical property detection: 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 testing machine, and a tape head test sample with the width of 12.5mm is adopted, and the tensile speed is 5mm/min.

Conductivity detection: according to the GB/T3048.2-2007 electric wire and cable electric property test method part 2: resistivity test of metal material, the tester is ZFD microcomputer bridge DC resistance tester, sample width is 20mm, length is 500mm.

And (3) detecting the microstructure: the microstructure properties of the material were evaluated according to YS/T347-2004, method for measuring the average grain size of copper and copper alloys, and YS/T449-2002, method for examining the microstructure of cast and worked copper and copper alloys. The former is mainly used for the evaluation of average grain size, and the latter is mainly used for the evaluation of phase area content

Cutting index: the cutting performance is evaluated according to a cutting performance detection method in appendix B of YS-T647-2007 copper zinc bismuth tellurium alloy bars, and the cutting index of C36000 (HPb 63-3) is set as 100%.

Surface roughness test conditions: and (3) measuring the surface of the turned bar by using a surface roughness measuring instrument by referring to GB/T1031-2009 surface structure contour method surface roughness parameters and values thereof.

The lower the measured surface roughness Ra value is, the smoother the surface of the sample is, the excellent cutting performance of the material is indirectly shown, and meanwhile, the electroplating performance of the material is also favorably improved.

Cold riveting test conditions: machining a phi 4.77mm bar on a numerical control lathe to a terminal with the length of 30mm, drilling a hole with the inner diameter phi 3.0mm and the depth of 6mm at a riveting end of the terminal, slowly applying 1-3 KN pressure to the riveting end in a terminal riveting tester until cracks appear on the wall of the phi 3.0 hole, stopping applying the pressure, and recording the compression ratio of Kong Waijing change when the riveting cracks. Under the same cold riveting test condition, the larger the compression ratio is when the cold riveting cracks, which indicates that the cold riveting performance of the material is better.

Turning test conditions: the process is carried out on a numerical control lathe, wherein the rotating speed of the lathe is 2000r/min, the feed rate is 0.2mm, and the feed speed is 50mm/min.

TABLE 1 compositions/wt% of inventive and comparative examples

Numbering	Cu	In	Sn	Ni	Pb	Zn	Others
								Example 1	62.5	0.66	0.32	0.11	0.08	Surplus	0.03La+0.03Ce
Example 2	61.8	0.57	0.29	0.22	0.09	Surplus	0.04Mg
								Example 3	62.4	0.74	0.35	0.18	0.07	Surplus	0.05Zr+0.02Mn
Example 4	63.1	0.76	0.33	0.10	0.07	Surplus
								Comparative example	58.6	/	0.82	0.043	0.06	Surplus	0.01Fe+0.31Si+0.1P

TABLE 2 microstructure and mechanical properties of inventive and comparative examples

TABLE 3 Properties of inventive and comparative examples

Claims

1. A brass alloy characterized by: the brass comprises the following components in percentage by mass: 61-65 wt%, pb: < 0.1wt%, in:0.1 to 1.0wt%, sn:0.2 to 0.5wt%, ni:0.1 to 0.5wt%, and the balance of Zn and inevitable impurities; the microstructure of the brass contains an alpha phase, a beta phase and a gamma-In phase, wherein the area content of the alpha phase is 85-98%, and the area content of the gamma-In phase is 4-10%; the average size of the gamma-In phase is less than or equal to 5 mu m, and the average size of the alpha phase is less than or equal to 10 mu m.

2. A brass alloy in accordance with claim 1, wherein: and at least one of La, ce, mg, mn and Zr, the total amount is 0.01-0.2 wt%.

3. A brass alloy in accordance with any one of claims 1 to 2, wherein: the brass has a tensile strength of 500 to 550MPa, a hardness HV5 of 140 to 170, an elongation of 5 to 18%, and an electric conductivity of not less than 27% IACS.

4. A brass alloy in accordance with any one of claims 1 to 2, wherein: the cutting rate of the brass is more than 80% of C3600, the compression ratio during cold riveting cracking is more than 80%, and the surface roughness Ra of the brass after turning is less than 1 mu m.

5. A method of manufacturing a brass alloy in accordance with any one of claims 1 to 2, wherein: the preparation method comprises the following preparation steps:

6. A method of making a brass alloy in accordance with claim 5, wherein: in the step 3), the ingot is heated before extrusion, the heating process is carried out in three stages, and the preheating stage is as follows: the temperature is controlled between 200 and 300 ℃, and the heating time is 20 to 30min; a heating stage: the temperature is controlled to be 400-600 ℃, and the heating time is 10-30 min; and (3) a heat preservation stage: 650-750 ℃ and heating time of 10-30 min.

7. A method of making a brass alloy in accordance with claim 5, wherein: in the step 5), the annealing process is carried out in two stages, and the preheating stage is as follows: the temperature is controlled between 150 ℃ and 250 ℃, and the temperature rise time is 5min to 20min; and (3) a heat preservation stage: the temperature is controlled at 300-420 ℃, and the heating time is 60-150 min.