CN110157965B - Free-cutting aluminum-copper alloy extrusion bar and preparation method thereof - Google Patents

Free-cutting aluminum-copper alloy extrusion bar and preparation method thereof Download PDF

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CN110157965B
CN110157965B CN201910550945.3A CN201910550945A CN110157965B CN 110157965 B CN110157965 B CN 110157965B CN 201910550945 A CN201910550945 A CN 201910550945A CN 110157965 B CN110157965 B CN 110157965B
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aluminum
copper alloy
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bar
ingot
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CN110157965A (en
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陈文泗
罗铭强
王顺成
聂德键
易鹏
林丽荧
金娜
郑健全
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Guangdong Xingfa Aluminium Jiangxi Co ltd
Guangdong Xingfa Aluminium Co ltd
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    • 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
    • B21C23/00—Extruding metal; Impact extrusion
    • B21C23/002—Extruding materials of special alloys so far as the composition of the alloy requires or permits special extruding methods of sequences
    • 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
    • C22C1/026—Alloys based on aluminium
    • 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
    • C22C1/03—Making non-ferrous alloys by melting using master 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
    • C22C1/06—Making non-ferrous alloys with the use of special agents for refining or deoxidising
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/12—Alloys based on aluminium with copper as the next major constituent
    • C22C21/14—Alloys based on aluminium with copper as the next major constituent with silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/12—Alloys based on aluminium with copper as the next major constituent
    • C22C21/16—Alloys based on aluminium with copper as the next major constituent with magnesium
    • 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
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/057—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with copper as the next major constituent

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  • Crystallography & Structural Chemistry (AREA)
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Abstract

The invention provides an easy-cutting aluminum-copper alloy extrusion bar and a preparation method thereof, wherein the aluminum-copper alloy extrusion bar comprises the following components in percentage by mass: 3.5-4.5% of Cu, 0.6-0.9% of Mg, 0.6-1.0% of Mn, 0.4-0.6% of Cr, 0.15-0.25% of Ce, 0.06-0.1% of B, 0.01-0.02% of Ti, 0.0004-0.0008% of C, 0.8-1.2% of Sn, 0.3-0.5% of Bi, less than or equal to 0.2% of Fe, less than or equal to 0.1% of Si, and the balance of Al and other impurity elements. The aluminum-copper alloy extrusion bar does not contain heavy metal element lead, meets the requirement of environmental protection, has good mechanical property and excellent cutting processing property, has easy breakage of cutting chips, does not stick to a knife or wind the knife, and is beneficial to improving the production efficiency of cutting processing, the surface smoothness of products and the dimensional precision.

Description

Free-cutting aluminum-copper alloy extrusion bar and preparation method thereof
Technical Field
The invention belongs to the technical field of aluminum alloy preparation, and particularly relates to an easy-cutting aluminum-copper alloy extrusion bar and a preparation method thereof.
Background
The free-cutting aluminum alloy generally refers to aluminum alloy with easily broken chips, no sticking, no winding and convenient chip removal. The free-cutting aluminum alloy can be cut at a higher speed or with a larger feed amount, so that the production efficiency of cutting can be obviously improved, and the precision aluminum alloy parts with good surface smoothness and high dimensional precision can be obtained.
The existing free-cutting aluminum alloy mainly improves the cutting performance of the aluminum alloy by adding low-melting-point metal elements, the temperature of aluminum alloy cutting scraps is increased due to frictional heat generation in the high-speed cutting process of the aluminum alloy, when the temperature of the aluminum alloy cutting scraps at the accessory of the contact point of a cutter is close to or reaches the melting point of the low-melting-point metal elements and the components thereof, the low-melting-point metal elements and the components thereof are softened or melted, the aluminum alloy cutting scraps are broken, and the effects that the cutting scraps are not stuck to the cutter, do not wind the cutter and are convenient to remove scraps are achieved.
The aluminum-copper alloy is an aluminum alloy taking copper as a main alloy element, belongs to an aluminum alloy capable of being strengthened by heat treatment, has the characteristics of high strength and high hardness, and can be widely applied to the fields of electronic appliances, transportation, mechanical equipment, aerospace, weaponry and the like, such as parts of transmission valves, inflation valves, hubs, pistons, air guide wheels, wheel discs, pulleys, bearings, rivets, bolts, screws and the like. These many aluminum-copper alloy parts are generally obtained by subjecting an aluminum-copper alloy extruded bar to a large number of cutting processes such as turning, milling, planing, drilling, tapping, etc., and thus the aluminum-copper alloy extruded bar is required to have excellent cutting processability.
With the development of economic society, the existing free-cutting aluminum-copper alloy extruded bar still has the following problems in the production and use processes:
(1) the existing free-cutting aluminum-copper alloy extrusion bar generally contains lead elements, such as 2005, 2007, 2011, 2030 and other brands of free-cutting aluminum-copper alloys, and lead is a toxic heavy metal element and has harmful and polluting effects on human bodies and the environment. With the improvement of living standard and the enhancement of environmental protection consciousness of people, the lead-containing free-cutting aluminum-copper alloy is forbidden to be produced, sold and used in various countries. A strict technical barrier is set for products containing harmful substances such as lead in many countries internationally, and electronic and electric products containing 6 harmful substances such as lead, cadmium, mercury and the like, including ten major types of electronic and electric products such as household appliances, communication and the like, are prohibited from being sold in the market of the european union. Therefore, there is an urgent need to develop a lead-free-cutting aluminum-copper alloy extruded bar.
(2) With the popularization and application of high-speed numerical control machines such as a numerical control lathe, a numerical control milling machine, a numerical control drilling machine and the like, the cutting performance of the conventional easy-cutting aluminum-copper alloy extruded bar is more and more difficult to meet the high-speed cutting processing requirement of the numerical control machine, and the development of the aluminum-copper alloy extruded bar with more excellent cutting performance is urgently needed.
(3) The existing easy-cutting aluminum-copper alloy extruded bar generally has the problems of low strength, large high-temperature brittleness, poor corrosion resistance and the like.
Therefore, the existing free-cutting aluminum-copper alloy extruded bar and the preparation method thereof still need to be improved and developed.
Disclosure of Invention
In view of the above problems and disadvantages, the present invention aims to provide an easily-cut aluminum-copper alloy extruded bar and a method for manufacturing the same, which improve the cutting performance, strength, high temperature resistance and corrosion resistance of the aluminum-copper alloy extruded bar by optimizing the composition and extrusion process of the aluminum-copper alloy.
The technical scheme of the invention is realized as follows:
the invention provides an easy-cutting aluminum-copper alloy extrusion bar which is characterized by comprising the following components in percentage by mass: 3.5-4.5% of Cu, 0.6-0.9% of Mg, 0.6-1.0% of Mn, 0.4-0.6% of Cr, 0.15-0.25% of Ce, 0.06-0.1% of B, 0.01-0.02% of Ti, 0.0004-0.0008% of C, 0.8-1.2% of Sn, 0.3-0.5% of Bi, less than or equal to 0.2% of Fe, less than or equal to 0.1% of Si, the balance of Al and other impurity elements, the content of single other impurity elements is less than or equal to 0.05%, and the total content is less than or equal to 0.15%.
Wherein Cu is the main strengthening element of the aluminum-copper alloy extruded bar, has the solid solution strengthening effect and can form CuA with All2The strengthening phase obviously enhances the strength of the aluminum-copper alloy extruded bar. The Cu content is too low, the strength of the aluminum-copper alloy extruded bar is insufficient, the Cu content is too high, the hot cracking tendency of the aluminum-copper alloy extruded bar is large, the corrosion resistance is poor, in addition, the Cu price is higher, the Cu content is too high, and the production cost of the aluminum-copper alloy extruded bar is also obviously increased. The performance requirements and production cost factors of the aluminum-copper alloy extrusion bar are integrated, so that the Cu content is selected to be 3.5-4.5%.
The solid solubility of Mg in the aluminum-copper alloy extruded bar is high, and the strength of the aluminum-copper alloy extruded bar can be improved through solid solution strengthening. Mg and Si may also form Mg2The Si strengthening phase strengthens the strength of the aluminum-copper alloy extruded bar. The higher the Mg content, the higher the strength of the aluminum bronze alloy extruded bar, but too high a Mg content also reduces the plasticity of the aluminum bronze alloy extruded bar. Therefore, the Mg content is selected to be 0.6 to 0.9%.
The Mn and the Cr belong to transition group elements, and the inventor finds that by simultaneously adding Mn and Cr in a composite manner, part of Mn and Cr can be directly dissolved into an aluminum matrix, so that the bonding force between aluminum atoms is increased, the diffusion process of the aluminum atoms and the decomposition speed of solid solution are reduced, and the thermal stability of the aluminum matrix at high temperature is improved. Secondly, MnAl can be formed among Mn, Cr and Al6、CrAl7And MnCrAl12The multiple dispersion strengthening phases are distributed on the aluminum matrix and the crystal boundary, so that the migration and dislocation movement of the crystal boundary and the sub-crystal boundary are hindered, the resistance of the dislocation movement in the aluminum matrix is increased, the rheology of the crystal boundary at high temperature is hindered, and the recrystallization temperature and the high-temperature stability of the aluminum-copper alloy extruded bar are obviously improved. The content of Mn and Cr is too low to achieve the effect, and the content of Mn and Cr is too high to easily form coarse intermetallic compounds to deteriorate the mechanical property of the aluminum-copper alloy. Therefore, the Mn content is selected to be 0.6 to 1.0%, and the Cr content is selected to be 0.4 to 0.6%.
The Ce in the aluminum-copper alloy extrusion bar mainly has the function of refining and modifying thick needlesA ferric rich phase. Fe is generally coarse acicular FeAl in the aluminum-copper alloy due to impurity element3、FeSiAl3The thick needle-like β -Fe iron-rich phases exist in the aluminum-copper alloy matrix, and the thick needle-like β -Fe iron-rich phases are hard brittle phases and can seriously cut the aluminum-copper alloy matrix, so that the thick needle-like β -Fe iron-rich phases become crack sources and crack propagation directions of aluminum-copper alloy fracture and harm the strength and the plasticity of an aluminum-copper alloy extruded bar3、FeSiAl3When the growth front edge of the iron-rich phase is equal, the growth of β -Fe iron-rich phase in needle shape is inhibited, finally the coarse needle-shaped β -Fe iron-rich phase can be converted into fine and uniform granular α -Fe iron-rich phase which is dispersed and distributed in the aluminum matrix, the harm of the coarse needle-shaped β -Fe iron-rich phase to the strength, the plasticity and the corrosion resistance of the aluminum-copper alloy extruded bar is eliminated, the strength, the plasticity and the corrosion resistance of the aluminum-copper alloy extruded bar are improved, in addition, Ce can also form stable CeAl with Al in thermodynamics4The phase is distributed on the crystal boundary to prevent crystal slippage and hinder the crystal boundary rheology at high temperature, thereby improving the high-temperature stability of the aluminum-copper alloy extruded bar. Therefore, 0.15 to 0.25% of Ce is selectively added.
Sn and Bi belong to low-melting-point elements, the melting point of Sn is 231.9 ℃, the melting point of Bi is 271.3 ℃, and the main function is to improve the cutting performance of the aluminum-copper alloy extrusion bar. After a large amount of experimental researches, the inventor discovers that low-melting-point elements such as Sn and Bi are added in a compounding manner, and when the content of Sn is 0.8-1.2% and the content of Bi is 0.3-0.5%, a Sn + Bi low-melting-point eutectic structure with a melting point lower than 200 ℃ can be obtained, so that the cutting performance of the aluminum-copper alloy extrusion bar is remarkably improved, and the aluminum-copper alloy extrusion bar has excellent cutting performance.
The B element mainly plays a role in refining and spheroidizing the Sn + Bi low-melting-point eutectic structure. After a great deal of experimental research, the inventor finds that the Sn + Bi low-melting-point eutectic structure is generally in a coarse continuous net distribution in the aluminum-copper alloy extruded bar, and the cutting performance of the aluminum-copper alloy extruded bar is reduced. And B is a surface active element and can be adsorbed on the grain boundary of the Sn + Bi eutectic structure, the Sn + Bi eutectic structure is refined and spheroidized, so that the Sn + Bi eutectic structure is converted into fine particles and spheres and is dispersed on an aluminum matrix, and the cutting performance of the aluminum-copper alloy extrusion bar is improved. The B content is too low to be effective, but not too high, so that the B content is selected to be 0.06-0.1%.
Ti and C are added into the aluminum-copper alloy liquid on line in the form of AlTi5C0.2 alloy wires, and mainly have the effects of refining grains, improving the uniformity of the structure and improving the strength and the plasticity of the aluminum-copper alloy extrusion bar. When the traditional AlTiB alloy grain refiner meets Mn and Cr transition group elements in an aluminum-copper alloy liquid, the traditional AlTiB alloy grain refiner can be poisoned to lose the grain refining effect. The inventor discovers through a large amount of experimental researches that the AlTi5C0.2 alloy grain refiner has an immunization function on poisoning of Mn and Cr, 0.2-0.4% of AlTi5C0.2 alloy wires are added, 0.01-0.02% of Ti and 0.0004-0.0008% of C are contained in the aluminum-copper alloy extruded bar, the aluminum-copper alloy can be refined into fine and uniform isometric crystals, the structural uniformity of the aluminum-copper alloy is obviously improved, and the strength and the plasticity of the aluminum-copper alloy extruded bar are improved.
Fe. Si is the main impurity element in the aluminum-copper alloy extruded bar. Fe. Si is an inevitable impurity element in the aluminum ingot, the higher the aluminum content of the aluminum ingot is, namely the higher the purity is, the lower the impurity elements such as Fe and Si are contained, and finally the lower the impurity elements such as Fe and Si in the aluminum-copper alloy extruded bar are, so that the performance of the aluminum-copper alloy extruded bar is ensured. However, the higher the purity of the aluminum ingot, the more expensive the aluminum ingot, which significantly increases the production cost of the aluminum-copper alloy extruded bar. The aluminum ingot with the aluminum content more than or equal to 99.7 percent is selected, so that impurity elements Fe in the aluminum-copper alloy extrusion bar are less than or equal to 0.2 percent, Si is less than or equal to 0.1 percent, the single content of other impurity elements is less than or equal to 0.05 percent, and the total content is less than or equal to 0.15 percent. Considering the performance requirement and production cost of the aluminum-copper alloy extruded bar comprehensively, an aluminum ingot with 99.7 percent of aluminum content is preferred.
The invention relates to a preparation method of a free-cutting aluminum-copper alloy extrusion bar, which is characterized by comprising the following steps of:
s001: according to the composition and mass percentage of the aluminum-copper alloy extrusion bar, selecting an aluminum ingot, a magnesium ingot, a tin ingot, a bismuth ingot, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-chromium alloy, an aluminum-cerium alloy, an aluminum-boron alloy and an aluminum-titanium-carbon alloy wire as raw materials to be proportioned;
s002: heating and melting an aluminum ingot, then adding a magnesium ingot, a tin ingot, a bismuth ingot, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-chromium alloy, an aluminum-cerium alloy and an aluminum-boron alloy, and stirring and melting into an aluminum-copper alloy liquid;
s003: carrying out blowing refining, degassing and impurity removing treatment on the aluminum-copper alloy liquid by adopting inert gas and a refining agent, slagging off and then standing for a period of time;
s004: introducing the aluminum-copper alloy liquid into a launder, and then adding an aluminum-titanium-carbon alloy wire for online refining treatment;
s005: enabling the aluminum-copper alloy liquid to sequentially flow through a degassing machine and a foamed ceramic filter plate which are arranged on a launder to carry out online degassing and filtering treatment;
s006: semi-continuously casting the aluminum-copper alloy liquid into an aluminum-copper alloy cast rod;
s007: carrying out two-stage homogenization treatment on the aluminum-copper alloy cast rod, and then forcibly cooling the aluminum-copper alloy cast rod to room temperature by water mist;
s008: heating the aluminum-copper alloy cast bar, extruding the aluminum-copper alloy cast bar into an aluminum-copper alloy extrusion bar, and then cooling the aluminum-copper alloy extrusion bar to room temperature by water mist;
s009: and carrying out two-stage aging treatment on the aluminum-copper alloy extruded bar, and cooling the aluminum-copper alloy extruded bar to room temperature along with the furnace to obtain the free-cutting aluminum-copper alloy extruded bar.
Preferably, in step S001, the aluminum content of the aluminum ingot is not less than 99.7%, the magnesium content of the magnesium ingot is not less than 99.95%, the tin content of the tin ingot is not less than 99.99%, the bismuth content of the bismuth ingot is not less than 99.99%, the aluminum-copper alloy is AlCu50, the aluminum-manganese alloy is AlMn10, the aluminum-chromium alloy is AlCr10, the aluminum-cerium alloy is AlCe5, the aluminum-boron alloy is AlB3, and the aluminum-titanium-carbon alloy wire is alti5c0.2 wire.
In the step S002, the step of heating and melting the aluminum ingot is to place the aluminum ingot in a furnace with a permanent magnetic stirring device at the bottom for heating and melting, and melt the aluminum ingot into aluminum-copper alloy liquid under the action of permanent magnetic stirring, wherein the melting temperature is 750-760 ℃.
Since Sn and Bi have high densities and have high specific gravities in the aluminum-copper alloy liquid, segregation is likely to occur, and it is generally difficult to prevent the segregation of Sn and Bi by manual stirring. Therefore, in order to prevent the segregation of Sn and Bi, it is preferable to perform melting in a furnace with a permanent magnet stirring at the bottom.
In the step S003, the inert gas is nitrogen or argon with the purity of more than or equal to 99.99 percent, the dosage of the refining agent accounts for 0.2-0.4 percent of the total weight of the raw materials, the blowing refining time is 8-12 minutes, and the standing time is 40-50 minutes.
The nitrogen and the argon are inert gases, the nitrogen or the argon can be used for blowing and refining in the furnace, the degassing and impurity removing effects are the same, but in order to ensure the degassing and impurity removing effects, the purity of the nitrogen or the argon must be more than or equal to 99.99%.
In the step S004, the adding amount of the aluminum-titanium-carbon alloy wire accounts for 0.2-0.4% of the total weight of the raw materials.
In the step S005, the rotation speed of a graphite rotor of the degasser is 445-455 rpm, the flow of inert gas nitrogen or argon is 0.8-1.2 cubic meters per hour, and the porosity of the foamed ceramic filter plate is 30-40 ppi.
The air holes and inclusions are common defects of the aluminum-copper alloy, and the defects are also crack sources for the aluminum-copper alloy to break and starting points of corrosion, which can reduce the mechanical property and the corrosion resistance of the aluminum-copper alloy. In order to improve the cleanliness of the aluminum-copper alloy, the inventor finds that on the basis of blowing, refining, degassing and impurity removal of the aluminum-copper alloy liquid in the furnace, the aluminum-copper alloy liquid sequentially flows through a degassing machine and a foamed ceramic filter plate which are arranged on a launder to carry out online degassing and filtering treatment, the aluminum-copper alloy liquid can be deeply purified, the aluminum-copper alloy with high cleanliness is obtained, and the aluminum-copper alloy is ensured to obtain sufficient mechanical property and corrosion resistance.
In the step S006, the casting temperature of the semi-continuous casting is 690-700 ℃, the casting speed is 90-100 mm/min, and the cooling water pressure is 0.6-0.8 MPa.
Since Sn and Bi have a large specific gravity, segregation is likely to occur during casting. In order to prevent the segregation of Sn and Bi, after repeated experiments, the invention discovers that the segregation of Sn and Bi can be effectively prevented by performing semi-continuous casting under the conditions that the casting temperature is 690-700 ℃, the casting speed is 90-100 mm/min and the pressure of cooling water is 0.6-0.8 MPa, and the aluminum-copper alloy cast rod with uniformly distributed Sn and Bi is obtained.
Preferably, in the step S007, the two-stage homogenization treatment includes heating the aluminum-copper alloy cast rod to 410-420 ℃ and maintaining the temperature for 2-3 hours, and then continuously heating to 440-450 ℃ and maintaining the temperature for 3-4 hours.
The homogenization treatment is intended to eliminate macro-micro segregation of elements such as Cu, Mg, Mn, Cr, etc. in the aluminum-copper alloy cast bar and to melt coarse intermetallic compounds as sufficiently as possible. After carrying out a large number of experimental investigation on the homogenization treatment process of the aluminum-copper alloy cast rod, the inventor finds that the two-stage homogenization treatment process is adopted, the aluminum-copper alloy cast rod is heated to 410-420 ℃ and is kept at the temperature for 2-3 hours, then the temperature is continuously raised to 440-450 ℃ and is kept at the temperature for 3-4 hours, and then the aluminum-copper alloy cast rod is forcibly cooled to room temperature by water mist, so that macro-micro segregation of elements such as Cu, Mg, Mn, Cr and the like in the aluminum-copper alloy cast rod can be eliminated, coarse intermetallic compounds are fully dissolved, and the quality of the aluminum-copper alloy cast rod is ensured.
In the step S008, the heating temperature of the aluminum-copper alloy cast rod is 460-470 ℃, the temperature of the extrusion die is 410-420 ℃, the temperature of the extrusion cylinder is 400-410 ℃, the extrusion speed is 8-9 m/min, and the extrusion ratio is 10-20.
The extrusion process parameters not only directly affect the extrusion process and production efficiency, but also affect the internal and surface quality of the aluminum-copper alloy extruded bar. The extrusion process parameters are mainly embodied by influencing the heat balance of the aluminum-copper alloy extrusion process, the temperature of the aluminum-copper alloy cast rod, the extrusion die and the extrusion charging barrel is too low, or the extrusion speed is too high or the extrusion ratio is too large, the unreasonable matching can cause too large deformation and tensile strength, the aluminum-copper alloy rod cannot be smoothly extruded, the temperature is too high or the extrusion ratio is too small, the aluminum-copper alloy rod with excellent internal and surface quality cannot be obtained, and the production efficiency is too low if the extrusion speed is too low. After a large number of experiments and researches, the inventor discovers that under the conditions that the heating temperature of an aluminum-copper alloy cast bar is 460-470 ℃, the temperature of an extrusion die is 410-420 ℃, the temperature of an extrusion cylinder is 400-410 ℃, the extrusion speed is 8-9 m/min, and the extrusion ratio is 10-20, the aluminum-copper alloy extruded bar with excellent internal and surface quality can be obtained.
In the step S009, the two-stage aging treatment is to heat the aluminum-copper alloy extruded bar to 125-135 ℃ and preserve the temperature for 5-6 hours, and then continue to heat to 150-160 ℃ and preserve the temperature for 2-3 hours.
The aging process can directly influence CuAl2、Mg2The shape, size and distribution of the Si strengthening phase further influence the strength, plasticity and corrosion resistance of the aluminum-copper alloy extruded bar. The inventor carries out systematic research on the aging process of the aluminum-copper alloy extruded bar, and finds that the aluminum-copper alloy extruded bar can obtain the required strength, plasticity and corrosion resistance by adopting a two-stage aging process, heating the aluminum-copper alloy extruded bar to 125-135 ℃ and preserving the heat for 5-6 hours, and then continuously heating to 150-160 ℃ and preserving the heat for 2-3 hours.
Compared with the prior art, the invention has the following beneficial effects:
(1) the free-cutting aluminum-copper alloy extrusion bar provided by the invention only contains Sn and Bi low-melting-point elements, does not contain lead, does not bring harm and pollution to human health and ecological environment, and belongs to a green and environment-friendly free-cutting aluminum-copper alloy extrusion bar;
(2) according to the invention, the composition of the low-melting-point metal elements Sn and Bi is optimally designed, so that the low-melting-point eutectic phases of Sn and Bi are uniformly dispersed and distributed on an aluminum substrate, the cutting performance of the aluminum-copper alloy extrusion bar is obviously improved, and during high-speed cutting processing, the cutting chips are easy to break, do not stick to a knife, do not wind the knife and are convenient to remove chips;
(3) according to the invention, Mn and Cr are added in a compounding manner to form various dispersion particles distributed on an aluminum matrix, so that the migration and dislocation movement of crystal boundaries and subgrain boundaries are hindered, the rheology of the crystal boundaries at high temperature is prevented, and the recrystallization temperature and the high-temperature stability of the aluminum-copper alloy extrusion bar are improved;
(4) according to the invention, through refining modification treatment, the coarse needle-shaped β -Fe iron-rich phase is converted into fine and uniform particles and is dispersed on the aluminum matrix, so that the influence of the relative strength and corrosion resistance of the coarse needle-shaped β -Fe iron-rich phase is eliminated, and the strength and corrosion resistance of the aluminum-copper alloy extrusion bar are improved;
(5) according to the invention, through optimizing and designing the casting, homogenizing, extruding and aging process parameters of the aluminum-copper alloy, the cleanliness and the structural component uniformity of the aluminum-copper alloy are improved, and the strength, the cutting performance, the high-temperature stability and the corrosion resistance of the aluminum-copper alloy extruded bar are further improved;
(6) the free-cutting aluminum-copper alloy extrusion bar has the room-temperature tensile strength of more than 480MPa, the elongation after fracture of more than 14 percent, the tensile strength at the high temperature of 150 ℃ of more than 400MPa and the elongation after fracture of more than 16 percent, and during high-speed cutting processing, chips are easy to break, do not stick to a knife, do not wind the knife, are convenient to remove chips, and have excellent cutting performance, high-temperature stability and corrosion resistance.
Drawings
FIG. 1 is a process flow chart of the method for preparing the free-cutting aluminum-copper alloy extruded bar of the invention.
FIG. 2 is a map showing the morphology of turnings of an extruded aluminum-copper alloy bar according to example 1.
FIG. 3 is a map showing the morphology of turnings of an extruded aluminum-copper alloy bar in example 2.
FIG. 4 is a map showing the morphology of turnings of an extruded aluminum-copper alloy bar according to example 3.
FIG. 5 is a view showing the appearance of turning chips of an extruded aluminum-copper alloy bar according to comparative example 1.
FIG. 6 is a drawing showing the morphology of turnings of an extruded aluminum bronze alloy bar according to comparative example 2.
FIG. 7 is a map showing the morphology of turnings of an extruded aluminum bronze alloy bar according to comparative example 3.
Detailed Description
In order to make the objects, technical solutions and effects of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings by way of examples and comparative examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
An easy-cutting aluminum-copper alloy extrusion bar comprises the following components in percentage by mass: 4.1 percent of Cu, 0.8 percent of Mg0.8 percent of Mn, 0.5 percent of Cr, 0.2 percent of Ce, 0.08 percent of B, 0.015 percent of Ti, 0.0006 percent of C, 1.1 percent of Sn, 0.4 percent of Bi0.4 percent of Bi, less than or equal to 0.2 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and other impurity elements, the single content of other impurity elements is less than or equal to 0.05 percent, and the total content is less than or equal to 0;
the preparation method is shown in figure 1 and comprises the following steps:
s001: according to the composition and mass percentage of the aluminum-copper alloy extrusion bar, selecting an aluminum ingot with 99.7 percent of aluminum content, a magnesium ingot with 99.95 percent of magnesium content, a tin ingot with 99.99 percent of tin content, a bismuth ingot with 99.99 percent of bismuth content, AlCu50 alloy, AlMn10 alloy, AlCr10 alloy, AlFe 5 alloy, AlB3 alloy and AlTi5C0.2 alloy wire as raw materials for proportioning;
s002: placing an aluminum ingot in a furnace with a permanent magnetic stirring device at the bottom, heating and melting at 755 ℃, then adding a magnesium ingot, a tin ingot, a bismuth ingot, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-chromium alloy, an aluminum-cerium alloy and an aluminum-boron alloy, and melting into an aluminum-copper alloy liquid under the action of permanent magnetic stirring;
s003: carrying out blowing refining on the aluminum-copper alloy liquid for 10 minutes by adopting nitrogen with the purity of 99.99 percent and a refining agent accounting for 0.3 percent of the total weight of the raw materials to carry out degassing and impurity removal treatment, and standing for 45 minutes after slagging off;
s004: introducing the aluminum-copper alloy liquid into a launder, and then adding an AlTi5C0.2 alloy wire for online refining treatment;
s005: enabling the aluminum-copper alloy liquid to sequentially flow through a degassing machine with the rotation speed of a graphite rotor being 450 revolutions per minute and the nitrogen flow rate being 0.9 cubic meter per hour and a foamed ceramic filter plate with the porosity being 35ppi, which are arranged on a launder, to carry out online degassing and filtering treatment;
s006: semi-continuously casting the aluminum-copper alloy liquid into an aluminum-copper alloy cast rod under the conditions that the casting temperature of the semi-continuous casting is 695 ℃, the casting speed is 95 mm/min and the pressure of cooling water is 0.7 MPa;
s007: heating the aluminum-copper alloy cast rod to 415 ℃, preserving heat for 2.5 hours, then continuously heating to 445 ℃, preserving heat for 3.5 hours, carrying out two-stage homogenization treatment, and then carrying out forced cooling by water mist to room temperature;
s008: extruding the aluminum-copper alloy cast bar into an aluminum-copper alloy extruded bar under the conditions that the heating temperature of the aluminum-copper alloy cast bar is 465 ℃, the temperature of an extrusion die is 415 ℃, the temperature of an extrusion cylinder is 405 ℃, the extrusion speed is 8.5 m/min and the extrusion ratio is 15, and then cooling the aluminum-copper alloy extruded bar to room temperature by water mist;
s009: heating the aluminum-copper alloy extrusion bar to 130 ℃, preserving heat for 5.5 hours, then continuously heating to 155 ℃, preserving heat for 2.5 hours, carrying out two-stage aging treatment, and cooling to room temperature along with the furnace to obtain the aluminum-copper alloy extrusion bar.
Example 2
An easy-cutting aluminum-copper alloy extrusion bar comprises the following components in percentage by mass: 3.5 percent of Cu, 0.9 percent of Mg0.9 percent, 0.6 percent of Mn, 0.6 percent of Cr, 0.25 percent of Ce, 0.06 percent of B, 0.01 percent of Ti, 0.0004 percent of C, 1.2 percent of Sn, 0.3 percent of Bi0.3 percent, less than or equal to 0.2 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and other impurity elements, the single content of other impurity elements is less than or equal to 0.05 percent, and the total content is less than or;
the preparation method comprises the following steps:
s001: according to the composition and mass percentage of the aluminum-copper alloy extrusion bar, selecting an aluminum ingot with 99.7 percent of aluminum content, a magnesium ingot with 99.95 percent of magnesium content, a tin ingot with 99.99 percent of tin content, a bismuth ingot with 99.99 percent of bismuth content, AlCu50 alloy, AlMn10 alloy, AlCr10 alloy, AlFe 5 alloy, AlB3 alloy and AlTi5C0.2 alloy wire as raw materials for proportioning;
s002: placing an aluminum ingot in a furnace with a permanent magnetic stirring device at the bottom, heating and melting at 760 ℃, then adding a magnesium ingot, a tin ingot, a bismuth ingot, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-chromium alloy, an aluminum-cerium alloy and an aluminum-boron alloy, and melting into an aluminum-copper alloy liquid under the action of permanent magnetic stirring;
s003: argon with the purity of 99.99 percent and a refining agent accounting for 0.4 percent of the total weight of the raw materials are adopted to carry out blowing refining on the aluminum-copper alloy liquid for 8 minutes, degassing and impurity removing treatment is carried out, and the aluminum-copper alloy liquid is kept stand for 50 minutes after slagging off;
s004: introducing the aluminum-copper alloy liquid into a launder, and then adding an AlTi5C0.2 alloy wire for online refining treatment;
s005: enabling the aluminum-copper alloy liquid to sequentially flow through a degassing machine with a graphite rotor rotating speed of 455 revolutions per minute and a nitrogen flow of 0.8 cubic meter per hour and a foamed ceramic filter plate with porosity of 30ppi, and performing online degassing and filtering treatment;
s006: semi-continuously casting the aluminum-copper alloy liquid into an aluminum-copper alloy cast bar under the conditions that the casting temperature of the semi-continuous casting is 700 ℃, the casting speed is 90 mm/min and the cooling water pressure is 0.8 MPa;
s007: heating the aluminum-copper alloy cast rod to 420 ℃ and preserving heat for 2 hours, then continuously heating to 440 ℃ and preserving heat for 4 hours to carry out two-stage homogenization treatment, and then forcibly cooling water mist to room temperature;
s008: extruding the aluminum-copper alloy cast bar into an aluminum-copper alloy extruded bar under the conditions that the heating temperature of the aluminum-copper alloy cast bar is 460 ℃, the temperature of an extrusion die is 420 ℃, the temperature of an extrusion cylinder is 410 ℃, the extrusion speed is 8 m/min and the extrusion ratio is 20, and then cooling the aluminum-copper alloy extruded bar to room temperature by water mist;
s009: heating the aluminum-copper alloy extrusion bar to 135 ℃ and preserving heat for 5 hours, then continuously heating to 150 ℃ and preserving heat for 3 hours to carry out two-stage aging treatment, and cooling to room temperature along with the furnace to obtain the aluminum-copper alloy extrusion bar.
Example 3
An easy-cutting aluminum-copper alloy extrusion bar comprises the following components in percentage by mass: 4.5 percent of Cu, 0.6 percent of Mg0.6 percent of Mn, 0.4 percent of Cr, 0.15 percent of Ce, 0.1 percent of B, 0.02 percent of Ti, 0.0008 percent of C, 0.8 percent of Sn, 0.5 percent of Bi0.5 percent of Fe, less than or equal to 0.2 percent of Si, less than or equal to 0.1 percent of Si, the balance of Al and other impurity elements, the single content of other impurity elements is less than or equal to 0.05 percent, and the total content is less than or equal to 0;
the preparation method comprises the following steps:
s001: according to the composition and mass percentage of the aluminum-copper alloy extrusion bar, selecting an aluminum ingot with 99.7 percent of aluminum content, a magnesium ingot with 99.95 percent of magnesium content, a tin ingot with 99.99 percent of tin content, a bismuth ingot with 99.99 percent of bismuth content, AlCu50 alloy, AlMn10 alloy, AlCr10 alloy, AlFe 5 alloy, AlB3 alloy and AlTi5C0.2 alloy wire as raw materials for proportioning;
s002: placing an aluminum ingot in a furnace with a permanent magnetic stirring device at the bottom, heating and melting at 750 ℃, then adding a magnesium ingot, a tin ingot, a bismuth ingot, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-chromium alloy, an aluminum-cerium alloy and an aluminum-boron alloy, and melting into an aluminum-copper alloy liquid under the action of permanent magnetic stirring;
s003: carrying out blowing refining on the aluminum-copper alloy liquid for 12 minutes by adopting nitrogen or argon with the purity of 99.99 percent and a refining agent accounting for 0.2 percent of the total weight of the raw materials, degassing and removing impurities, and standing for 40 minutes after slagging off;
s004: introducing the aluminum-copper alloy liquid into a launder, and then adding an AlTi5C0.2 alloy wire for online refining treatment;
s005: enabling the aluminum-copper alloy liquid to sequentially flow through a degassing machine with a graphite rotor rotating speed of 445 revolutions per minute and a nitrogen flow of 1.2 cubic meters per hour and a foamed ceramic filter plate with porosity of 40ppi arranged on a launder to carry out online degassing and filtering treatment;
s006: semi-continuously casting the aluminum-copper alloy liquid into an aluminum-copper alloy cast bar under the conditions that the casting temperature of the semi-continuous casting is 690 ℃, the casting speed is 100 mm/min and the pressure of cooling water is 0.6 MPa;
s007: heating the aluminum-copper alloy cast rod to 410 ℃ and preserving heat for 3 hours, then continuously heating to 450 ℃ and preserving heat for 3 hours to carry out two-stage homogenization treatment, and then forcibly cooling water mist to room temperature;
s008: extruding the aluminum-copper alloy cast bar into an aluminum-copper alloy extruded bar under the conditions that the heating temperature of the aluminum-copper alloy cast bar is 470 ℃, the temperature of an extrusion die is 410 ℃, the temperature of an extrusion cylinder is 400 ℃, the extrusion speed is 9 m/min and the extrusion ratio is 10, and then cooling the aluminum-copper alloy extruded bar to room temperature by water mist;
s009: heating the aluminum-copper alloy extrusion bar to 125 ℃ and preserving heat for 6 hours, then continuously heating to 160 ℃ and preserving heat for 2 hours to carry out two-stage aging treatment, and cooling to room temperature along with the furnace to obtain the aluminum-copper alloy extrusion bar.
Comparative example 1
An aluminum-copper alloy extrusion bar comprises the following components in percentage by mass: 4.1 percent of Cu, 0.8 percent of Mg, 0.9 percent of Mn0.5 percent of Cr, 0.2 percent of Ce, 0.08 percent of B, 0.015 percent of Ti, 0.0006 percent of C, 0.5 percent of Sn, 0.4 percent of Bi, less than or equal to 0.2 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and other impurity elements, the single content of other impurity elements is less than or equal to 0.05 percent, and the total content is less than or equal to 0.15 percent;
the preparation method comprises the following steps:
s001: according to the composition and mass percentage of the aluminum-copper alloy extrusion bar, selecting an aluminum ingot with 99.7 percent of aluminum content, a magnesium ingot with 99.95 percent of magnesium content, a tin ingot with 99.99 percent of tin content, a bismuth ingot with 99.99 percent of bismuth content, AlCu50 alloy, AlMn10 alloy, AlCr10 alloy, AlFe 5 alloy, AlB3 alloy and AlTi5C0.2 alloy wire as raw materials for proportioning;
s002: placing an aluminum ingot in a furnace with a permanent magnetic stirring device at the bottom, heating and melting at 755 ℃, then adding a magnesium ingot, a tin ingot, a bismuth ingot, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-chromium alloy, an aluminum-cerium alloy and an aluminum-boron alloy, and melting into an aluminum-copper alloy liquid under the action of permanent magnetic stirring;
s003: carrying out blowing refining on the aluminum-copper alloy liquid for 10 minutes by adopting nitrogen with the purity of 99.99 percent and a refining agent accounting for 0.3 percent of the total weight of the raw materials to carry out degassing and impurity removal treatment, and standing for 45 minutes after slagging off;
s004: introducing the aluminum-copper alloy liquid into a launder, and then adding an AlTi5C0.2 alloy wire for online refining treatment;
s005: enabling the aluminum-copper alloy liquid to sequentially flow through a degassing machine with the rotation speed of a graphite rotor being 450 revolutions per minute and the nitrogen flow rate being 0.9 cubic meter per hour and a foamed ceramic filter plate with the porosity being 35ppi, which are arranged on a launder, to carry out online degassing and filtering treatment;
s006: semi-continuously casting the aluminum-copper alloy liquid into an aluminum-copper alloy cast rod under the conditions that the casting temperature of the semi-continuous casting is 695 ℃, the casting speed is 95 mm/min and the pressure of cooling water is 0.7 MPa;
s007: heating the aluminum-copper alloy cast rod to 415 ℃, preserving heat for 2.5 hours, then continuously heating to 445 ℃, preserving heat for 3.5 hours, carrying out two-stage homogenization treatment, and then carrying out forced cooling by water mist to room temperature;
s008: extruding the aluminum-copper alloy cast bar into an aluminum-copper alloy extruded bar under the conditions that the heating temperature of the aluminum-copper alloy cast bar is 465 ℃, the temperature of an extrusion die is 415 ℃, the temperature of an extrusion cylinder is 405 ℃, the extrusion speed is 8.5 m/min and the extrusion ratio is 15, and then cooling the aluminum-copper alloy extruded bar to room temperature by water mist;
s009: heating the aluminum-copper alloy extrusion bar to 130 ℃, preserving heat for 5.5 hours, then continuously heating to 155 ℃, preserving heat for 2.5 hours, carrying out two-stage aging treatment, and cooling to room temperature along with the furnace to obtain the aluminum-copper alloy extrusion bar.
Comparative example 2
An aluminum-copper alloy extrusion bar comprises the following components in percentage by mass: 3.5 percent of Cu, 0.9 percent of Mg, 0.6 percent of Mn0.6 percent of Cr, 0.25 percent of Ce, 0.03 percent of B, 0.01 percent of Ti, 0.0004 percent of C, 1.2 percent of Sn, 0.3 percent of Bi, less than or equal to 0.2 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and other impurity elements, the single content of other impurity elements is less than or equal to 0.05 percent, and the total content is less than or equal to 0.15 percent;
the preparation method comprises the following steps:
s001: according to the composition and mass percentage of the aluminum-copper alloy extrusion bar, selecting an aluminum ingot with 99.7 percent of aluminum content, a magnesium ingot with 99.95 percent of magnesium content, a tin ingot with 99.99 percent of tin content, a bismuth ingot with 99.99 percent of bismuth content, AlCu50 alloy, AlMn10 alloy, AlCr10 alloy, AlFe 5 alloy, AlB3 alloy and AlTi5C0.2 alloy wire as raw materials for proportioning;
s002: placing an aluminum ingot in a furnace with a permanent magnetic stirring device at the bottom, heating and melting at 760 ℃, then adding a magnesium ingot, a tin ingot, a bismuth ingot, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-chromium alloy, an aluminum-cerium alloy and an aluminum-boron alloy, and melting into an aluminum-copper alloy liquid under the action of permanent magnetic stirring;
s003: argon with the purity of 99.99 percent and a refining agent accounting for 0.4 percent of the total weight of the raw materials are adopted to carry out blowing refining on the aluminum-copper alloy liquid for 8 minutes, degassing and impurity removing treatment is carried out, and the aluminum-copper alloy liquid is kept stand for 50 minutes after slagging off;
s004: introducing the aluminum-copper alloy liquid into a launder, and then adding an AlTi5C0.2 alloy wire for online refining treatment;
s005: enabling the aluminum-copper alloy liquid to sequentially flow through a degassing machine with a graphite rotor rotating speed of 455 revolutions per minute and a nitrogen flow of 0.8 cubic meter per hour and a foamed ceramic filter plate with porosity of 30ppi, and performing online degassing and filtering treatment;
s006: semi-continuously casting the aluminum-copper alloy liquid into an aluminum-copper alloy cast bar under the conditions that the casting temperature of the semi-continuous casting is 700 ℃, the casting speed is 90 mm/min and the cooling water pressure is 0.8 MPa;
s007: heating the aluminum-copper alloy cast rod to 420 ℃ and preserving heat for 2 hours, then continuously heating to 440 ℃ and preserving heat for 4 hours to carry out two-stage homogenization treatment, and then forcibly cooling water mist to room temperature;
s008: extruding the aluminum-copper alloy cast bar into an aluminum-copper alloy extruded bar under the conditions that the heating temperature of the aluminum-copper alloy cast bar is 460 ℃, the temperature of an extrusion die is 420 ℃, the temperature of an extrusion cylinder is 410 ℃, the extrusion speed is 8 m/min and the extrusion ratio is 20, and then cooling the aluminum-copper alloy extruded bar to room temperature by water mist;
s009: heating the aluminum-copper alloy extrusion bar to 135 ℃ and preserving heat for 5 hours, then continuously heating to 150 ℃ and preserving heat for 3 hours to carry out two-stage aging treatment, and cooling to room temperature along with the furnace to obtain the aluminum-copper alloy extrusion bar.
Comparative example 3
An aluminum-copper alloy extrusion bar comprises the following components in percentage by mass: 4.5 percent of Cu, 0.6 percent of Mg, 1.0 percent of Mn1, 0.4 percent of Cr, 0.05 percent of Ce, 0.1 percent of B, 0.02 percent of Ti, 0.0008 percent of C, 0.8 percent of Sn, 0.5 percent of Bi, less than or equal to 0.2 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and other impurity elements, the single content of other impurity elements is less than or equal to 0.05 percent, and the total content is less than or equal to 0.15 percent;
the preparation method comprises the following steps:
s001: according to the composition and mass percentage of the aluminum-copper alloy extrusion bar, selecting an aluminum ingot with 99.7 percent of aluminum content, a magnesium ingot with 99.95 percent of magnesium content, a tin ingot with 99.99 percent of tin content, a bismuth ingot with 99.99 percent of bismuth content, AlCu50 alloy, AlMn10 alloy, AlCr10 alloy, AlFe 5 alloy, AlB3 alloy and AlTi5C0.2 alloy wire as raw materials for proportioning;
s002: placing an aluminum ingot in a furnace with a permanent magnetic stirring device at the bottom, heating and melting at 750 ℃, then adding a magnesium ingot, a tin ingot, a bismuth ingot, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-chromium alloy, an aluminum-cerium alloy and an aluminum-boron alloy, and melting into an aluminum-copper alloy liquid under the action of permanent magnetic stirring;
s003: carrying out blowing refining on the aluminum-copper alloy liquid for 12 minutes by adopting nitrogen or argon with the purity of 99.99 percent and a refining agent accounting for 0.2 percent of the total weight of the raw materials, degassing and removing impurities, and standing for 40 minutes after slagging off;
s004: introducing the aluminum-copper alloy liquid into a launder, and then adding an AlTi5C0.2 alloy wire for online refining treatment;
s005: enabling the aluminum-copper alloy liquid to sequentially flow through a degassing machine with a graphite rotor rotating speed of 445 revolutions per minute and a nitrogen flow of 1.2 cubic meters per hour and a foamed ceramic filter plate with porosity of 40ppi arranged on a launder to carry out online degassing and filtering treatment;
s006: semi-continuously casting the aluminum-copper alloy liquid into an aluminum-copper alloy cast bar under the conditions that the casting temperature of the semi-continuous casting is 690 ℃, the casting speed is 100 mm/min and the pressure of cooling water is 0.6 MPa;
s007: heating the aluminum-copper alloy cast rod to 410 ℃ and preserving heat for 3 hours, then continuously heating to 450 ℃ and preserving heat for 3 hours to carry out two-stage homogenization treatment, and then forcibly cooling water mist to room temperature;
s008: extruding the aluminum-copper alloy cast bar into an aluminum-copper alloy extruded bar under the conditions that the heating temperature of the aluminum-copper alloy cast bar is 470 ℃, the temperature of an extrusion die is 410 ℃, the temperature of an extrusion cylinder is 400 ℃, the extrusion speed is 9 m/min and the extrusion ratio is 10, and then cooling the aluminum-copper alloy extruded bar to room temperature by water mist;
s009: heating the aluminum-copper alloy extrusion bar to 125 ℃ and preserving heat for 6 hours, then continuously heating to 160 ℃ and preserving heat for 2 hours to carry out two-stage aging treatment, and cooling to room temperature along with the furnace to obtain the aluminum-copper alloy extrusion bar.
According to the national standard GB/T16865-2013 sample and method for tensile test of wrought aluminum, magnesium and alloy processing products thereof, the aluminum-copper alloy extruded bars of examples 1-3 and comparative examples 1-3 are processed into standard tensile samples, the standard tensile samples are stretched at room temperature of 25 ℃ and high temperature of 150 ℃ on an INSTRON-200 type electronic tensile testing machine, the stretching rate is 2 mm/min, the room temperature tensile strength, the high temperature tensile strength and the elongation after fracture of the aluminum-copper alloy extruded bars are detected, and the detection results are respectively shown in Table 1.
TABLE 1 room temperature and high temperature tensile mechanical properties of the extruded bars of the examples and comparative examples of aluminum-copper alloys
Figure BDA0002105403870000211
Figure BDA0002105403870000221
In order to examine the cutting performance of the aluminum-copper alloy extruded bars of the examples and the comparative examples, samples were taken from the aluminum-copper alloy extruded bars of the examples 1 to 3 and the comparative examples 1 to 3, respectively, and a high-speed turning test was performed on a CTN3500 lathe, where the tool material was YG8 hard alloy, the tool feed rate was 0.5 mm, the rotational speed was 3000 rpm, the cutting performance of the aluminum-copper alloy extruded bars was evaluated by observing the morphology of the turnings, fig. 2 to 4 are the morphology of the turnings of the aluminum-copper alloy extruded bars of the examples 1 to 3, respectively, and fig. 5 to 7 are the morphology of the turnings of the aluminum-copper alloy extruded bars of the comparative examples 1 to 3, respectively.
As can be seen from Table 1, the tensile strength at room temperature of the aluminum-copper alloy extruded bar of the embodiment of the present invention is greater than 480MPa, the elongation after fracture is greater than 14%, the tensile strength at 150 ℃ of the aluminum-copper alloy extruded bar is greater than 400MPa, and the elongation after fracture is greater than 16%. As can be seen from fig. 2 to 4, the aluminum-copper alloy extruded bars of examples 1 to 3 of the present invention have fine and uniform turning chips, and no long turning chips are observed, indicating that the aluminum-copper alloy extruded bars of the present invention have excellent cutting performance, and the cutting chips are easily broken during high-speed cutting.
As can be seen from fig. 5 and 6, the aluminum bronze alloy extruded rod of comparative example 1 has a Sn content of less than 0.8%, the aluminum bronze alloy extruded rod of comparative example 2 has a B content of less than 0.06%, and the shavings of the aluminum bronze alloy extruded rod are in a long strip shape, indicating that the aluminum bronze alloy extruded rods of comparative examples 1 and 2 have poor cutting workability and the shavings are not easily broken during high-speed cutting. As can be seen from Table 1, the aluminum-copper alloy extruded bar of comparative example 3 has a room-temperature tensile strength of less than 480MPa, a post-fracture elongation of less than 14%, a tensile strength at a high temperature of 150 ℃ of less than 400MPa, and a post-fracture elongation of less than 16% due to a Ce content of less than 0.15%.
As can be seen from the comparison of the aluminum-copper alloy extruded bars in the above examples and comparative examples, the strength, cutting performance and high temperature resistance of the aluminum-copper alloy can be remarkably improved by optimally designing the component compositions of Sn and Bi, carrying out refinement modification treatment on a coarse acicular Fe-rich phase and carrying out refinement spheroidization treatment on a Sn + Bi eutectic structure by adding B elements, and the free-cutting aluminum-copper alloy does not contain heavy metal elements such as lead and the like, and belongs to the green and environment-friendly free-cutting aluminum-copper alloy.

Claims (4)

1. The free-cutting aluminum-copper alloy extruded bar is characterized in that: the aluminum-copper alloy extrusion bar comprises the following components in percentage by mass: 3.5-4.5% of Cu, 0.6-0.9% of Mg, 0.6-1.0% of Mn, 0.4-0.6% of Cr, 0.15-0.25% of Ce0.06-0.1% of B, 0.01-0.02% of Ti, 0.0004-0.0008% of C, 0.8-1.2% of Sn, 0.3-0.5% of Bi, less than or equal to 0.2% of Fe, less than or equal to 0.1% of Si, the balance of Al and other impurity elements, the content of single other impurity elements is less than or equal to 0.05%, and the total content is less than or equal to 0.15%; the preparation method of the aluminum-copper alloy extrusion bar comprises the following steps:
s001: according to the composition and mass percentage of the aluminum-copper alloy extrusion bar, selecting an aluminum ingot, a magnesium ingot, a tin ingot, a bismuth ingot, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-chromium alloy, an aluminum-cerium alloy, an aluminum-boron alloy and an aluminum-titanium-carbon alloy wire as raw materials to be proportioned, wherein the aluminum-titanium-carbon alloy wire is an AlTi5C0.2 wire;
s002: placing an aluminum ingot in a furnace with a permanent magnetic stirring device at the bottom for heating and melting, then adding a magnesium ingot, a tin ingot, a bismuth ingot, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-chromium alloy, an aluminum-cerium alloy and an aluminum-boron alloy, and melting into an aluminum-copper alloy liquid under the action of permanent magnetic stirring, wherein the melting temperature is 750-760 ℃;
s003: carrying out blowing refining, degassing and impurity removing treatment on the aluminum-copper alloy liquid by adopting inert gas and a refining agent, slagging off and then standing for a period of time;
s004: introducing the aluminum-copper alloy liquid into a launder, and then adding an aluminum-titanium-carbon alloy wire for online refining treatment;
s005: enabling the aluminum-copper alloy liquid to sequentially flow through a degassing machine and a foamed ceramic filter plate which are arranged on a launder to carry out online degassing and filtering treatment;
s006: the aluminum-copper alloy liquid is semi-continuously cast into an aluminum-copper alloy cast rod, the casting temperature of the semi-continuous casting is 690-700 ℃, the casting speed is 90-100 mm/min, and the pressure of cooling water is 0.6-0.8 MPa;
s007: heating the aluminum-copper alloy cast rod to 410-420 ℃ and preserving heat for 2-3 hours, then continuously heating to 440-450 ℃ and preserving heat for 3-4 hours to perform two-stage homogenization treatment, and then forcibly cooling water mist to room temperature;
s008: heating the aluminum-copper alloy cast bar, extruding the aluminum-copper alloy cast bar into an aluminum-copper alloy extrusion bar, wherein the heating temperature of the aluminum-copper alloy cast bar is 460-470 ℃, the temperature of an extrusion die is 410-420 ℃, the temperature of an extrusion cylinder is 400-410 ℃, the extrusion speed is 8-9 m/min, the extrusion ratio is 10-20, and then cooling the aluminum-copper alloy extrusion bar to room temperature by water mist;
s009: heating the aluminum-copper alloy extrusion bar to 125-135 ℃ and preserving heat for 5-6 hours, then continuously heating to 150-160 ℃ and preserving heat for 2-3 hours to carry out two-stage aging treatment, and cooling to room temperature along with the furnace to obtain the free-cutting aluminum-copper alloy extrusion bar.
2. The free-cutting aluminum bronze alloy extruded bar according to claim 1, wherein: in the step S001, the aluminum content of the aluminum ingot is more than or equal to 99.7%, the magnesium content of the magnesium ingot is more than or equal to 99.95%, the tin content of the tin ingot is more than or equal to 99.99%, the bismuth content of the bismuth ingot is more than or equal to 99.99%, the aluminum-copper alloy is AlCu50, the aluminum-manganese alloy is AlMn10, the aluminum-chromium alloy is AlCr10, the aluminum-cerium alloy is AlCe5, the aluminum-boron alloy is AlB3, and the aluminum-titanium-carbon alloy wire is AlTi5C0.2 wire.
3. The free-cutting aluminum bronze alloy extruded bar according to claim 1, wherein: in the step S003, the inert gas is nitrogen or argon with the purity of more than or equal to 99.99 percent; the amount of the refining agent accounts for 0.2-0.4% of the total weight of the raw materials; the blowing refining time is 8-12 minutes, and the standing time is 40-50 minutes.
4. The free-cutting aluminum bronze alloy extruded bar according to claim 1, wherein: in the step S005, the rotation speed of a graphite rotor of the degasser is 445-455 rpm, the flow of inert gas nitrogen or argon is 0.8-1.2 cubic meters per hour, and the porosity of the foamed ceramic filter plate is 30-40 ppi.
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