CN116219223A - Brass alloy bar and preparation method thereof - Google Patents

Brass alloy bar and preparation method thereof Download PDF

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Publication number
CN116219223A
CN116219223A CN202310004150.9A CN202310004150A CN116219223A CN 116219223 A CN116219223 A CN 116219223A CN 202310004150 A CN202310004150 A CN 202310004150A CN 116219223 A CN116219223 A CN 116219223A
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phase
brass alloy
extrusion
blank
gamma
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刘雄雄
郑恩奇
瞿福水
叶嘉慧
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Ningbo Jintian Copper Group Co Ltd
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Ningbo Jintian Copper Group Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
    • C22C9/04—Alloys based on copper with zinc as the next major constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
    • B21C37/04—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of bars or wire
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • B22D11/004—Copper alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Metal Extraction Processes (AREA)

Abstract

The invention discloses a brass alloy bar, which is characterized in that: the brass alloy comprises the following components in percentage by mass: 64-66%, te:1.0 to 2.0 percent, as:0.1 to 1.0 percent, sn:0.2 to 1.0 percent, X: 0.001-0.1%, X is selected from at least one of Mg, nd and Mo, and the balance is Zn and unavoidable impurities. Te, as, sn, X is added into brass, the addition amount of Cu, te, as, sn, X is controlled, and finally the tensile strength of the brass alloy bar is realized: 400-460 MPa, elongation: 15-25% of the steel with the hardness: 120-150 HV, has good cutting, riveting resistance and corrosion resistance, and the surface roughness of the finished bar is less than 2 mu m after machined into a part, meets the test requirement of 5% neutral salt fog for 72h, and does not generate cracks after the part is subjected to riveting processing with deformation of more than 80%.

Description

Brass alloy bar and preparation method thereof
Technical Field
The invention belongs to the technical field of copper alloy, and particularly relates to a brass alloy bar and a preparation method thereof.
Background
Brass has good cold and hot processing performance, is commonly used for preparing various complex parts, and along with the development of the times, the application field of brass is expanded, and the requirements on the comprehensive performance of brass are increased gradually:
1. good cutting performance is required. The drilling and turning performances are included, so that the high-speed precision lathe machining can be met, the production efficiency of parts is guaranteed, and the dimensional accuracy is good. At present, some special high-precision parts are required to have surface roughness below 2 mu m after being subjected to turning processing so as to have good surface finish.
2. It is required to have good corrosion resistance. Brass, because of containing zinc, forms brittle beta phase that can reduce the corrosion resistance of the material. Especially under the high humidity and high salinity environment, brass is easier to corrode and dezincification, and the service life of the part materials can be greatly reduced due to serious dezincification corrosion. Some brass products applied to severe environments are required to meet the neutral salt spray test for at least 72 hours.
3. Good riveting resistance is required. After the precise turning, part of brass parts are subjected to cold deformation plastic pressure processing, and the riveting resistance performance also shows the cold deformation plastic processing of the parts. If the riveting resistance is general, the part is extremely easy to crack after being riveted. At present, the riveting deformation processing rate of some special parts exceeds 80%, so that the riveting resistance requirement is more severe and important.
Meanwhile, with the improvement of environmental protection consciousness of various countries, lead-free brass becomes a necessary trend of future development, and the Pb content is required to be lower than 0.1 percent according to European RoHS requirements. The mature leadless free-cutting brass in the current market mainly comprises bismuth brass and silicon brass. The cutting performance of other applied lead-free brass cannot meet the machining requirement of a high-speed precise lathe, the surface roughness after the turning is far higher than 2 mu m, and the dimensional accuracy of parts cannot meet the use requirement. The silicon brass has high copper content and good corrosion resistance, but contains a certain amount of silicon element, so that the hard brittleness formed by the silicon element is unfavorable for the riveting resistance of the material, especially, after large-processing riveting processing, the probability of cracking and breaking of parts is extremely high, and the current silicon brass product is mainly applied to the field of hot forging processing, so that the silicon brass existing on the market at present cannot meet the performance requirements. Bismuth brass has cutting performance close to that of lead brass, but bismuth element is easy to form a low-brittleness film phase after high-temperature heat treatment, so that the brittleness of the material is greatly increased, and the riveting processing is not facilitated. Meanwhile, in order to ensure good cutting performance of the bismuth brass, the copper content in the component is generally controlled below 62%, if a high-temperature heat treatment process is not performed, a certain amount of beta phase is reserved in a matrix, the corrosion resistance of the material is generally, the requirement of over 72h of a neutral salt spray test cannot be met stably, and the higher beta phase amount is not beneficial to improving the riveting resistance.
In view of the foregoing, the lead-free brass currently available in the market cannot meet the requirements of good cutting, riveting resistance and corrosion resistance, so that development of a lead-free brass alloy with excellent comprehensive properties is needed to meet the future requirements.
Disclosure of Invention
The first technical problem to be solved by the invention is to provide a brass alloy bar which is free-cutting, corrosion-resistant and excellent in cold workability.
The second technical problem to be solved by the invention is to provide a preparation method of a brass alloy bar.
The invention solves the first technical problem by adopting the technical scheme that: a brass alloy bar, characterized in that: the brass alloy comprises the following components in percentage by mass: 64-66%, te:1.0 to 2.0 percent, as:0.1 to 1.0 percent, sn:0.2 to 1.0 percent, X: 0.001-0.1%, X is selected from at least one of Mg, nd and Mo, and the balance is Zn and unavoidable impurities.
The lower limit of Cu element is controlled at 64%, so as to inhibit the formation of brittle beta phase and improve the riveting resistance and corrosion resistance of the material. When the Cu content in the brass alloy is too low, the Zn content is increased, the beta phase in the material matrix is increased, the beta phase belongs to an easy-to-corrode phase, and a corrosion channel formed by the beta phase is extremely easy to oxidize and corrode in a salt fog environment. Meanwhile, the brittleness of the material is increased, and the plasticity is reduced, so that the risk of riveting cracking is increased. The upper limit of Cu element is controlled at 66 percent, so as to ensure the machinability of the material. If the Cu content is too high, the plasticity of the material is further improved, the viscosity of the material is increased during cutting processing, and chip breakage is not easy to occur. Therefore, the main purpose of controlling the Cu content to be 64-66% is to ensure balance among various performances.
The purpose of the Te element addition is to form a cutting phase to improve the cutting properties of the material. Gamma-Cu formed by Te and Cu, sn and Zn elements 2 Te phase is distributed in matrix in form of soft particles with low melting point, and if Te content is less than 1%, gamma-Cu is formed 2 The Te phase quantity is too small to meet the cutting performance requirement of the invention. If the Te content is higher than 2%, on the one hand, the formed gamma-Cu will be 2 The Te phase is oversized, so that the brittleness of the material is greatly increased, and the riveting is not facilitated; on the other hand, too high Te can increase the hot working plasticity of the material, and the blank is extremely easy to crack in the extrusion process.
The aim of adding As element is to further improve the corrosion resistance of the material, and As can inhibit dezincification corrosion. Under the condition of the invention, if the As content is lower than 0.1%, the thickness of the material dezincification layer is more than 100 mu m easily in an acidic or salt fog environment, and the thicker the material dezincification layer is, the more unfavorable is the passing of salt fog performance test; if the As content is higher than 1%, the heat conduction performance of the alloy becomes low, transverse stress is more easily formed in the casting process when the heat conduction performance is lower, and the risk of cracking after solidification of the cast ingot is increased. Meanwhile, if too high As is added, the cold and hot workability of the material is also unfavorable, so the content of As needs to be controlled within the range of 0.1-1.0 percent.
The Sn element is added to improve the cutting performance and corrosion resistance of the material. In the invention, sn forms gamma-Cu with Te, cu and Zn 2 Te free cutting compared with Cu without Sn addition 2 The Te phase material is more brittle and has lower melting point, so that the cutting performance is more excellent. Meanwhile, the gamma phase formed by Sn element in the brass matrix can inhibit dezincification corrosion of the material As the As element, so that the corrosion resistance of the material is further improved. The invention controls the lower limit of Sn element to be 0.2 percent, and aims to ensure gamma-Cu 2 The formation amounts of Te phase and γ phase are thereby effectively attained the above-mentioned free-cutting and corrosion-resistant effects. If the Sn element is too high, the material is further increasedHardness, and reduced plasticity. On one hand, the tensile deformation plasticity of the material can be reduced, and the fracture risk is increased; on the other hand, the hardness and brittleness of the material are increased, and the material is extremely easy to crack after riveting.
The Mg, nd and Mo elements can assist in improving the cutting performance and the riveting resistance of the material. The addition of Mg can improve cutting performance, and simultaneously can effectively remove oxygen in the casting process as a strong reducing agent, thereby further improving the processing plasticity and quality of the material. If the Mg element is excessively added, the improvement of the above properties is not facilitated, but the workability and the riveting resistance of the material are deteriorated. Nd and Mo elements have similar actions, can effectively remove impurities and purify, reduce the phenomenon of weakening grain boundaries by smelting and casting inclusions, reduce the uniformity of material performance if the inclusions exist, and are unfavorable for improving the riveting resistance.
Preferably, the microstructure of the brass alloy has an α -phase as a matrix phase, and the area ratio of the β -phase is 2% or less. If the beta phase is a corrosion-prone brittle phase and the beta phase proportion exceeds 2%, on one hand, the brittleness of the material is increased, and the improvement of the riveting-resistant performance is not facilitated; on the other hand, dezincification corrosion of the material is increased, which is unfavorable for improving corrosion resistance.
Preferably, the microstructure of the brass alloy further comprises a second phase comprising gamma phase, gamma-Cu 2 Te phase, wherein the area ratio of gamma phase is 0.1-1%, gamma-Cu 2 The area ratio of Te phase is 1-5%. The gamma phase is less than 0.1%, the dezincification corrosion inhibition effect of the material is not obvious, the gamma phase exceeds 1%, the brittleness of the material is increased, and particularly, the material is extremely easy to crack when cold deformation processing is carried out. gamma-Cu 2 Te phase is lower than 1%, which is unfavorable for obtaining ideal cutting performance; gamma-Cu 2 Te phase exceeds 5%, which increases brittleness of the material when thermally deformed, and particularly when deformed by extrusion thermal processing, cracks of the extruded material are extremely likely to be formed.
Preferably, the alpha phase size: 10-20 mu m, beta phase size less than or equal to 5 mu m, gamma phase size: 0.1-1 mu m, gamma-Cu 2 Te phase size: 0.01-3 mu m. If the alpha phase size is less than 10 μm, the hardness and strength of the material are increased as a matrix phase, which is disadvantageous in obtaining the desired rivet resistance, and if the alpha phase size exceeds 20 μm, the number of grain boundaries is reduced, indirectly resulting in gamma-Cu distributed in the grain boundaries 2 The Te phase number decreases, thereby affecting cutting performance. The beta phase is used as a harmful phase, the content of the beta phase needs to be strictly controlled, if the size of the beta phase exceeds 5 mu m, the beta phase distributed in the region can increase the brittleness of the material, the riveting resistance is not facilitated, and the corrosion resistance is also affected. The gamma phase mainly improves corrosion resistance, and if the size is less than 0.1 mu m, the improvement effect is not remarkable, and if the size exceeds 1 mu m, the working plasticity of the material is deteriorated, and cold deformation stretching and riveting resistance are not facilitated. gamma-Cu 2 Te phase mainly improves machinability, and if the size is less than 0.01 μm, gamma-Cu distributed on grain boundary 2 The Te phase has insignificant cutting effect, and if the size exceeds 3 μm, on the one hand, the reduction of unit area of gamma-Cu results 2 The distribution quantity of Te phase affects cutting performance and uniformity and stability of material performance.
Preferably, the brass alloy bar has a tensile strength: 400-460 MPa, elongation: 15-25% of the steel with the hardness: 120-150 HV.
The invention solves the second technical problem by adopting the technical proposal that: the preparation method of the brass alloy bar is characterized by comprising the following preparation steps:
1) Smelting: batching according to the requirements of the required components, and adding the materials into a smelting furnace for smelting at the smelting temperature of 1000-1080 ℃;
2) Casting: copper water is led out from a crystallizer to be processed into cast ingots, and the casting temperature is 950-1050 ℃;
3) Extruding: the extrusion heating temperature of the cast ingot is 680-740 ℃, and the extrusion heating time is as follows: 2-6 h, extrusion ratio: 100-500 parts; extrusion speed: 10-15 mm/s to obtain an extrusion blank, and cooling the extrusion blank to room temperature with the cooling speed controlled below 50 ℃/min;
4) And (3) disc pulling: pickling the extruded blank, and then placing the pickled extruded blank in a disc drawing device for drawing, wherein the drawing processing rate is 20-40%;
5) Annealing: softening and annealing the coiled blank, and heating up at a rate: 5-30 ℃/min, and the heating time is as follows: 20-120 min, and the heat preservation temperature is as follows: 500-550 ℃, and the heat preservation time is as follows: after the heat preservation is finished, the mixture is rapidly cooled for 150 to 360 minutes, and the cooling speed is 50 to 600 ℃/s;
6) And (3) joint drawing: pickling the annealed blank, and then placing the annealed blank in a combined drawing device for drawing, wherein the drawing processing rate is as follows: 7-15%, drawing rate: 20-100 m/min.
The extrusion heating temperature of the cast ingot is 680-740 ℃, the tissue matrix is transformed from alpha phase to beta phase under the temperature condition, more beta phases are formed under the high temperature condition, and the extrusion heat deformation plasticity is improved. If the temperature is lower than 680 ℃, the heat distortion plasticity of the cast ingot can not meet the extrusion requirement; if the temperature is higher than 740 ℃, the grain growth is unfavorable for the uniformity of the extruded blank structure, and the high temperature is easy to cause gamma-Cu 2 Te phase is gathered to affect the processing plasticity and cutting performance of the material. The lower limit of the extrusion heating time is controlled to be 2 hours, so that the ingot is heated sufficiently and uniformly, and the problems of high temperature of the outer layer of the ingot and low temperature of the inner core are avoided. The extrusion heating time is controlled to be not more than 6 hours, so as to avoid overburning caused by excessive heating of the cast ingot, and if defects are easily formed on the surface of an extrusion blank of the overburning of the cast ingot, surface defects are caused, and the subsequent processing and use are affected.
In the extrusion process, the extrusion ratio is controlled to be 100-500, if the extrusion ratio is too low, the thermal deformation amount is small, the crystal grains are not fully crushed and recrystallized, and a large amount of as-cast structures of the extrusion blank are still reserved. If the extrusion ratio is too large, the extrusion force exceeds the equipment limit, and normal extrusion cannot be performed.
In the extrusion process, the extrusion speed is controlled to be 10-15 mm/s, if the extrusion speed is too low, the total extrusion time is increased, the ingot is cooled in the extrusion process, the temperature of the ingot can not meet the expected requirement when the ingot is extruded to the tail stage, and the extrusion effect and the extrusion tissue performance are directly affected. If the extrusion speed is too high, friction between an extrusion blank and an extrusion die is increased, so that surface scratch of the extrusion blank is easy to occur, and the brass alloy has higher Cu content, higher extrusion heating set temperature than that of common brass, and softer material extrusion processing, so that the probability of occurrence of thermal scratch is higher. Therefore, an appropriate extrusion speed needs to be strictly set.
In the extrusion step, the cooling rate of the extrusion billet is controlled so as to obtain desired extrusion billet performance and texture. The properties of the extrusion billet play a key role in the final finished product properties. The cooling speed of the extrusion blank is controlled below 50 ℃/min, which is favorable for keeping the extrusion blank in a long-time high-temperature phase change condition and promoting the beta-alpha phase change. The beta phase in the extrusion blank is reduced, so that the extension plasticity of the blank can be improved, and the requirement of the subsequent disc drawing processing rate is met. Meanwhile, the reduction of beta phase ratio in the tissue is also beneficial to the improvement of riveting resistance and corrosion resistance. If the cooling rate is too high, a large amount of beta-phase remains in the extrusion billet, and the performance requirement cannot be met. Therefore, the cooling speed of the extrusion billet needs to be strictly controlled below 50 ℃/min.
Through the extrusion process, the obtained extrusion blank has the following main key properties: hardness: 70-100 HV; tensile strength: 360-400 MPa; elongation percentage: 30-50%; alpha phase size: 10-25 mu m; the area ratio of the beta phase is below 5%.
The processing rate is controlled to be 20-40% in the disc drawing procedure, thereby realizing the further breaking of the tissue crystal grains, especially the longitudinal strip alpha phase change is changed into small particles, and meanwhile, gamma-Cu 2 Te phase is more dispersed because of crushing and refining, and is beneficial to improving the cutting performance of the material. If the processing rate is low, on one hand, the work hardening of the material is low, the hardness performance of the obtained final finished product is also low, and if the hardness of the finished product is low, the plasticity of the finished product is high, so that the cutting performance of the material is not facilitated. On the other hand, the crystal grains are not fully crushed, and the extrusion head and tail tissues generally have obvious difference due to temperature loss in the extrusion process, if the disc drawing processing rate after extrusion is low, the head and tail parts of the blank still have larger performance difference after disc drawing, and the difference can not be effectively eliminated after subsequent heat treatment processing, so that the stability of the performance of a finished product is directly influenced. If the processing rate is larger, the tensile deformation exceeds the limit of the plasticity of the material, and the alpha-phase crystal grain size is too small after disc drawing processing, which is not beneficial to improving the riveting resistance. Therefore, the key of the process is to control the size of the alpha phase and the gamma-Cu 2 Te phase size and hardness properties. The alpha phase grain size after disk pulling needs to be controlled to be 5-15 mu m, gamma-Cu 2 Te phase size: 0.01-2 mu m, and the hardness is controlled to be 150-170 HV.
In the annealing process, the heating rate and the heating time are controlled to ensure that the blank is heated uniformly, so that the problems of quick heating of the outer layer and slow heating of the inner layer of the coil material are avoided. If the temperature rising rate is too fast, the corresponding temperature rising time is short, and the maximum difference between the temperature of the inner layer and the temperature of the outer layer in the temperature rising process of the coil stock can reach more than 50 ℃. The uneven blank performance can cause poor drawing straightness of a finished product, and the poor straightness is not beneficial to precise turning processing, so that ideal cutting performance can not be obtained. If the heating rate is too slow, the corresponding heating time is long, and the uniformity of the annealed blank performance is favorable, but the production efficiency is seriously reduced, and the actual production reality condition is not met.
In the annealing process, the purposes of adopting the heat preservation temperature, the time and the cooling speed are to realize blank softening, improve the uniformity of performance and obtain ideal structure performance characteristics of a finished product. If the heat preservation temperature and time are low, blank softening cannot be effectively realized, uniformity is improved, and phase change occurs to obtain expected tissue characteristics of a finished product. If the heat preservation temperature and time are higher, the grains in the tissue grow excessively, and the performance uniformity is improved and the gamma-Cu is reversely acted 2 Te phase also grows up, which is unfavorable for cutting performance and riveting resistance. An extremely fast cooling rate is adopted to realize rapid cooling so that the material retains a high-temperature phase corresponding to the temperature condition. If the cooling rate is low, the annealed blank continues to undergo phase transition at the residual temperature, and the required tissue characteristics cannot be effectively controlled and obtained. The cooling speed is higher, but the limit of the cooling equipment is reached, so the invention controls the cooling speed condition after annealing to be 50-600 ℃/s.
In the combined drawing process, the drawing processing rate is controlled to be 7-15%, and the purpose is to control and obtain the mechanical properties of the required finished product. If the working rate is low, the plasticity of the finished product is high, so that on one hand, the straightness requirement of the finished product is affected, and on the other hand, the viscosity of the material during cutting is increased, and further, the cutting resistance is too high, so that good cutting performance cannot be realized. If the working ratio is too high, the work deformation hardening of the material is more remarkable, the strength and hardness are further improved, and the plasticity is further reduced. Although the cutting performance meets the requirements, the riveting resistance is not good. Therefore, in order to realize the balance between the cutting performance and the riveting resistance, the drawing processing rate of the finished product needs to be strictly controlled.
In the combined drawing step, the drawing rate is controlled to be 20-100 m/min. The purpose is to realize that the straightness of the finished bar meets the use requirement. Too high and too low a drawing rate are detrimental to obtaining the desired linearity requirement below 0.2 mm/m. If the straightness of the finished product is higher than 0.2mm/m, the bar is easy to centrifugally rotate during cutting, and high-speed turning cannot be performed, so that the surface roughness after turning is high, and the surface finish is seriously reduced.
Preferably, in the step 2), a horizontal continuous casting process is used to produce the ingot, and the specific casting method is as follows: traction-thrust-dwell, wherein the traction pitch: 20-60 mm, reverse pitch: 1-5 mm, traction speed: 5-20 mm/s, and the reverse thrust speed is as follows: the time ratio of traction, reverse thrust and pause is 1.0-3.0 at 1-5 mm/s: 1.
in the casting process, a traction mode of traction, back thrust and pause is adopted to promote nucleation, form more grains to effectively refine the grains, and prevent coarse grains from causing gamma-Cu distributed in grain boundaries 2 Te phase aggregation, if gamma-Cu in cast ingot 2 Te phase is aggregated in a large area, so that instability of ingot casting performance can be increased, and poor quality such as ingot casting cracking is easy to cause. In the subsequent extrusion process, if gamma-Cu 2 Te phase is distributed in an aggregation state, and can cause cracking during extrusion processing, so that a special traction mode and parameters are needed to obtain good ingot quality. And under the setting of the casting parameters, the cast ingot has good quality and is free of defect and cracking. Wherein gamma-Cu 2 The Te phase size is controlled to be 0.01-3 mu m, and the long alpha phase area accounts for less than 40% of the total alpha phase area. gamma-Cu 2 The Te phase size well ensures that the cast ingot meets the normal use of subsequent extrusion, and simultaneously controls the proportion of the strip-shaped alpha phase of the cast ingot, so that spherical equiaxed grains are easier to obtain after extrusion, and the uniform stability of the extruded billet structure is improved.
Compared with the prior art, the invention has the advantages that: te, as, sn, X is added into brass, the addition amount of Cu, te, as, sn, X is controlled, and finally the tensile strength of the brass alloy bar is realized: 400-460 MPa, elongation: 15-25% of the steel with the hardness: 120-150 HV, has good cutting, riveting resistance and corrosion resistance, and the surface roughness of the finished bar is less than 2 mu m after machined into a part, meets the test requirement of 5% neutral salt fog for 72h, and does not generate cracks after the part is subjected to riveting processing with deformation of more than 80%.
Detailed Description
The present invention is described in further detail below with reference to examples.
The invention provides 5 examples and 2 comparative examples, the specific compositions are shown in Table 1.
The preparation steps of the brass alloy bar of the example are as follows:
1) Smelting: batching according to the requirements of the required components, and adding the materials into a smelting furnace for smelting at the smelting temperature of 1000-1080 ℃;
2) Casting: copper water is led out from a crystallizer to be processed into cast ingots, and the casting temperature is 950-1050 ℃; the horizontal continuous casting process is adopted to produce cast ingots, and the concrete casting mode is as follows: traction-thrust-dwell, wherein the traction pitch: 20-60 mm, reverse pitch: 1-5 mm, traction speed: 5-20 mm/s, and the reverse thrust speed is as follows: the time ratio of traction, reverse thrust and pause is 2.0:1.
3) Extruding: the extrusion heating temperature of the cast ingot is 680-740 ℃, and the extrusion heating time is as follows: 2-6 h, extrusion ratio: 100-500: 1, a step of; extrusion speed: 10-15 mm/s to obtain an extrusion blank, and cooling the extrusion blank to room temperature with the cooling speed controlled below 50 ℃/min;
4) And (3) disc pulling: pickling the extruded blank, and then placing the pickled extruded blank in a disc drawing device for drawing, wherein the drawing processing rate is 20-40%;
5) Annealing: softening and annealing the blank after disc drawing, wherein the heating rate is 5-30 ℃/min, and the heating time is as follows: 20-120 min, and the heat preservation temperature is as follows: 500-550 ℃, and the heat preservation time is as follows: after the heat preservation is finished, the mixture is rapidly cooled for 150 to 360 minutes, and the cooling speed is 50 to 600 ℃/s;
6) And (3) joint drawing: pickling the annealed blank, and then placing the annealed blank in a combined drawing device for drawing, wherein the drawing processing rate is as follows: 7-15%, drawing rate: 20-100 m/min.
The key parameter control is shown in table 2 and table 3.
Comparative example 1 is H65.
Comparative example 2 is HBi59-1.
The following tests were performed on the microstructure of the example obtained:
1) Metallographic microscopic test: method for microstructure inspection of YS/T449-2002 copper and copper alloy cast and processed articles.
2) The second phase size and area ratio were photographed and measured by a scanning electron microscope.
The detection results are shown in Table 4.
The following performance tests were performed on the obtained examples and comparative examples:
1) Tensile strength detection: according to GB/T228.1-2021 section 1, metal tensile test: room temperature test methods 10, 20. Tensile strength was measured.
2) Hardness testing: GB/T4340.1-2009 Vickers hardness test section 1: test methods.
3) Turning test conditions: the process is carried out on a numerical control lathe, wherein the rotating speed of the lathe is 4000r/min, the feed amount is 0.2mm, and the feed speed is 50mm/min.
Under the same turning condition, the finer the appearance of the turning scraps, the better the cutting performance of the material is.
4) Surface roughness test conditions: and measuring the surface of the bar after turning by using a surface roughness measuring instrument with reference to GB/T1031-2009 surface roughness parameters and values thereof by a surface structure contour method.
The lower the measured surface roughness Ra value is, the smoother the sample surface is, the excellent cutting performance of the material is indirectly indicated, and the material electroplating performance is improved.
5) Cold riveting test conditions: the bar is processed on a numerical control lathe until a terminal with the length of 30mm and a terminal riveting end drills a hole with the inner diameter phi of 4.0mm and the depth of 6mm, the riveting end slowly applies pressure of 1-5 KN until the hole wall phi of 4.0 is cracked, the pressure application is stopped, and the compression ratio of Kong Waijing change during riveting cracking is recorded.
Under the same cold riveting test condition, the larger the compression ratio is during cold riveting cracking, the better the cold riveting performance of the material is shown.
6) Cutting index: the cutting performance was evaluated according to the method for measuring cutting performance in appendix B of YS-T647-2007 copper zinc bismuth tellurium alloy rod, and the cutting index of C36000 (HPb 63-3) was set to 100%.
7) Salt spray corrosion resistance: GB/T10125-2021 artificial atmosphere corrosion test salt spray test.
The detection results are shown in Table 5.
TABLE 1 Components of inventive examples and comparative examples/wt%
Figure BDA0004035479880000081
TABLE 2 casting and extrusion process parameters according to the examples of the invention
Figure BDA0004035479880000082
TABLE 3 parameters of the disk drawing, annealing, and combined drawing processes according to the embodiments of the invention
Figure BDA0004035479880000091
TABLE 4 microstructure of examples of the invention
Figure BDA0004035479880000092
TABLE 5 Properties of examples and comparative examples of the invention
Figure BDA0004035479880000101
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Claims (7)

1. A brass alloy bar, characterized in that: the brass alloy comprises the following components in percentage by mass: 64-66%, te:1.0 to 2.0 percent, as:0.1 to 1.0 percent, sn:0.2 to 1.0 percent, X: 0.001-0.1%, X is selected from at least one of Mg, nd and Mo, and the balance is Zn and unavoidable impurities.
2. A brass alloy bar as claimed in claim 1, wherein: the microstructure of the brass alloy takes an alpha phase as a matrix phase, and the area ratio of a beta phase is below 2 percent.
3. A brass alloy bar as claimed in claim 2, wherein: the microstructure of the brass alloy also comprises a second phase, wherein the second phase comprises gamma phase and gamma-Cu phase 2 Te phase, wherein the area ratio of gamma phase is 0.1-1%, gamma-Cu 2 The area ratio of Te phase is 1-5%.
4. A brass alloy bar as claimed in claim 3, wherein: the alpha phase size: 10-20 mu m, beta phase size less than or equal to 5 mu m, gamma phase size: 0.1-1 mu m, gamma-Cu 2 Te phase size: 0.01-3 mu m.
5. A brass alloy bar according to any of claims 1 to 4, wherein: tensile strength of the brass alloy bar: 400-460 MPa, elongation: 15-25% of the steel with the hardness: 120-150 HV.
6. A method of producing a brass alloy bar according to any one of claims 1 to 5, comprising the steps of:
1) Smelting: batching according to the requirements of the required components, and adding the materials into a smelting furnace for smelting at the smelting temperature of 1000-1080 ℃;
2) Casting: copper water is led out from a crystallizer to be processed into cast ingots, and the casting temperature is 950-1050 ℃;
3) Extruding: the extrusion heating temperature of the cast ingot is 680-740 ℃, and the extrusion heating time is as follows: 2-6 h, extrusion ratio: 100-500 parts; extrusion speed: 10-15 mm/s to obtain an extrusion blank, and cooling the extrusion blank to room temperature with the cooling speed controlled below 50 ℃/min;
4) And (3) disc pulling: pickling the extruded blank, and then placing the pickled extruded blank in a disc drawing device for drawing, wherein the drawing processing rate is 20-40%;
5) Annealing: softening and annealing the coiled blank, and heating up at a rate: 5-30 ℃/min, and the heating time is as follows: 20-120 min, and the heat preservation temperature is as follows: 500-550 ℃, and the heat preservation time is as follows: after the heat preservation is finished, the mixture is rapidly cooled for 150 to 360 minutes, and the cooling speed is 50 to 600 ℃/s;
6) And (3) joint drawing: pickling the annealed blank, and then placing the annealed blank in a combined drawing device for drawing, wherein the drawing processing rate is as follows: 7-15%, drawing rate: 20-100 m/min.
7. The method for producing a brass alloy bar according to claim 6, wherein: in the step 2), a horizontal continuous casting process is adopted to produce cast ingots, and the concrete casting mode is as follows: traction-thrust-dwell, wherein the traction pitch: 20-60 mm, reverse pitch: 1-5 mm, traction speed: 5-20 mm/s, and the reverse thrust speed is as follows: the time ratio of traction, reverse thrust and pause is 1.0-3.0 at 1-5 mm/s: 1.
CN202310004150.9A 2023-01-03 2023-01-03 Brass alloy bar and preparation method thereof Pending CN116219223A (en)

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