CN116043150A - Method for improving copper alloy segregation - Google Patents

Method for improving copper alloy segregation Download PDF

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CN116043150A
CN116043150A CN202310090540.2A CN202310090540A CN116043150A CN 116043150 A CN116043150 A CN 116043150A CN 202310090540 A CN202310090540 A CN 202310090540A CN 116043150 A CN116043150 A CN 116043150A
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segregation
copper alloy
homogenizing annealing
improving
dendrite
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周延军
杨少丹
杨冉
宋克兴
刘东东
郁炎
陈纪东
周菲
彭晓文
张学宾
柳亚辉
张国赏
岳鹏飞
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Henan University of Science and Technology
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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/02—Use of electric or magnetic effects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D7/00—Casting ingots, e.g. from ferrous metals
    • B22D7/005—Casting ingots, e.g. from ferrous metals from non-ferrous metals
    • 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
    • C22C9/00—Alloys based on copper
    • C22C9/06—Alloys based on copper with nickel or cobalt as the next major constituent
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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    • Y02P10/20—Recycling

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Abstract

The invention belongs to the field of casting of copper alloy, and particularly relates to a method for improving segregation of copper alloy. The method for improving the segregation of the copper alloy comprises the steps of carrying out two-stage homogenizing annealing on a copper alloy cast ingot; wherein the temperature of the first-stage homogenizing annealing is 900-950 ℃ for 30-60min, the temperature of the second-stage homogenizing annealing is 800-850 ℃ for 120-360min. According to the method for improving the segregation of the copper alloy, a two-stage homogenizing annealing process is adopted, the first-stage homogenizing annealing is performed at a high temperature for a short time, the rapid solid diffusion of the elements easy to segregate is realized, and coarse grains caused by the high temperature for a long time are avoided; and when the second-stage homogenizing annealing is performed at a low temperature, sufficient solid diffusion is realized, and segregation is further improved. By utilizing the two-stage homogenizing annealing mode, microscopic dendrite segregation can be improved, and tissue and performance homogenization can be realized.

Description

Method for improving copper alloy segregation
Technical Field
The invention belongs to the field of casting of copper alloy, and particularly relates to a method for improving segregation of copper alloy.
Background
The copper alloy has excellent conductivity, mechanical property, processing forming property and wear resistance and corrosion resistance, and is widely applied to the fields of aerospace, electronic information, rail transit, high-voltage electrical appliances, ocean engineering and the like. Common copper alloy systems include red copper (pure copper), brass (Cu-Zn system), white copper (Cu-Ni system), bronze (chrome bronze, tin phosphor bronze, tin bronze, beryllium bronze, etc.).
Among them, in the case of cu—ni—sn alloy containing Sn element, since the melting point of Sn element is low, the solid-liquid two-phase region of the alloy is wide, the crystallization temperature range is wide, the melt fluidity is poor, besides casting defects such as hot cracks and shrinkage porosity are liable to occur, the alloy grows up in dendrite form during solidification, and serious macro-component segregation (such as inverse segregation) and micro dendrite (intra-crystal) segregation are liable to occur, resulting in difficulty in controlling the uniformity of alloy components and the uniformity of structure.
The Chinese patent application with publication number of CN108060326A discloses an ultra-high-strength low-inverse segregation CuNiSn-based elastic copper alloy and a preparation method thereof, wherein dendrite segregation and inverse segregation of Sn are effectively inhibited by the combined addition of three elements of B, V and Sr. Wherein the Sr element pair reduces Sn anti-segregation mainly by regulating and controlling interfacial tension of molten Cu and Sn, and promoting uniform mixing of Sn in copper; B. the V element is added jointly to refine the as-cast structure. The method has a certain improvement effect on the uniformity distribution of Sn elements in the melt, but segregation still occurs due to the difference of melting points of multiple components and inconsistent solidification sequence in the solidification process, and part of coarse grains are caused by subsequent homogenizing annealing for a long time. Therefore, this approach has yet to be further improved in achieving uniformity of the segregation-prone copper alloy composition and uniformity control of the as-cast structure.
Disclosure of Invention
The invention aims to provide a method for improving copper alloy segregation, which solves the problem that the prior method is to be improved in the aspects of realizing the uniformity of easily segregated copper alloy components and the uniformity control of an as-cast structure.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a method for improving copper alloy segregation comprises the steps of carrying out two-stage homogenizing annealing on a copper alloy cast ingot; wherein the temperature of the first-stage homogenizing annealing is 900-950 ℃ for 30-60min, the temperature of the second-stage homogenizing annealing is 800-850 ℃ for 120-360min.
According to the method for improving the segregation of the copper alloy, a two-stage homogenizing annealing process is adopted, the first-stage homogenizing annealing is performed at a high temperature for a short time, the rapid solid diffusion of the elements easy to segregate is realized, and coarse grains caused by the high temperature for a long time are avoided; and when the second-stage homogenizing annealing is performed at a low temperature, sufficient solid diffusion is realized, and segregation is further improved. By utilizing the two-stage homogenizing annealing mode, microscopic dendrite segregation can be improved, and tissue and performance homogenization can be realized.
Preferably, the copper alloy cast ingot is obtained by casting a metal melt, the metal melt is obtained by adding a composite rare earth element into a copper alloy raw material, and the composite rare earth element is composed of Y, ce, eu and Rb, and the weight ratio of Y, ce, eu, rb is (0.02-1.0): (0.02-2.0): (0.01-0.8): (0.01-0.5). The added Y, eu and Rb elements react with oxygen to form Y 2 O 3 、Eu 2 O 3 、Rb 2 O 2 Wherein Eu is 2 O 3 Mainly has degassing effect, rb 2 O 2 Catalytic action in melt reaction and with Y 2 O 3 The alloy acts together with Ce to obviously refine grains, and the functions of deoxidizing, deslagging, refining grains and the like are realized through the synergistic effect of the multi-element composite rare earth.
Further preferably, the mass ratio of the Y element in the molten metal is 0.004-0.5%. By adopting the addition amount, the effect of the composite rare earth element can be realized under the condition of less addition amount, and the cost and the effect are both realized.
In order to further facilitate the addition of the composite rare earth element and ensure the accuracy of the addition amount, preferably, the composite rare earth element is added in the form of a composite rare earth element copper alloy, and the composite rare earth element copper alloy consists of the following components in percentage by mass: 0.02-1.0% of Y, 0.02-2.0% of Ce, 0.01-0.8% of Eu, 0.01-0.5% of Rb and the balance of Cu; the addition amount of the composite rare earth element copper alloy is 0.2-0.5% of the metal melt.
Preferably, the smelting temperature is 1150-1250 ℃. The smelting temperature can ensure that all raw materials are fully and completely smelted.
Preferably, electromagnetic stirring is applied when the molten metal solidifies. After the molten liquid is poured into the casting mould, external force influence is applied to the solidification process of the melt by adjusting the frequency or the current of the electromagnetic field. Under the action of electromagnetic field, dendrite segregation is inhibited, and component uniformity is ensured.
Preferably, the electromagnetic field applied with electromagnetic stirring has a frequency of 10-80Hz and a current of 20-100A. The electromagnetic field is controlled in the above parameter range, which can effectively influence the dendrite formation and growth in the solidification process, thereby improving the component uniformity and inhibiting microscopic dendrite segregation.
Preferably, the copper alloy is a Cu-Ni-Sn alloy. Because the addition amount of the composite rare earth element is small, the copper alloy is the copper alloy with segregation to be improved, and the composite rare earth element is not contained. The Cu-Ni-Sn alloy is used as an easy segregation alloy, and the segregation can be effectively improved by adopting the method provided by the invention, and the consistency and the uniformity of an as-cast structure are improved.
Drawings
FIG. 1 is a macroscopic corrosion structure of a Cu-Ni-Sn alloy prepared in example 1 of the present invention;
FIG. 2 shows the microstructure of the Cu-Ni-Sn alloy prepared in example 1 of the present invention.
Detailed Description
For Cu-Ni-Sn alloy containing Sn element, because the melting point of Sn element is lower, the solid-liquid two-phase area of the alloy is wide, the crystallization temperature range is large, the melt fluidity is poor, besides casting defects such as hot cracks, shrinkage porosity and the like are easy to generate, the alloy grows up in a dendrite mode during solidification, serious macroscopic component segregation (such as inverse segregation) and microscopic dendrite (intragranular) segregation are generated, and the control of the consistency of the components and the structure uniformity of the alloy is difficult.
Macroscopic composition segregation is mainly improved by regulating and controlling process parameters in the alloy casting process, and microscopic dendrite segregation is generally improved by homogenizing annealing. However, the conventional casting process has limited degree of controlling component segregation simply by means of a temperature field and a cooling process, and the homogenizing annealing process can improve dendrite segregation to a certain extent, but has limited degree of improving the influence on dendrite spacing and dendrite orientation distribution. Therefore, how to synergistically improve the segregation through various means has important significance for the ingot quality control and subsequent processing of the alloy.
As a preferable scheme, the general idea of the invention is to add multi-element composite rare earth in the smelting stage and apply strong magnetic field stirring in the casting stage and perform two-stage homogenizing annealing. Wherein, in the smelting stage, composite rare earth elements such as yttrium (Y), cerium (Ce), europium (Eu), rubidium (Rb) and the like are added into the alloy to purify the melt (remove trace impurity elements), improve the fluidity of the melt and refine the size of as-cast crystal grains; in the casting stage, dendrite formation and growth in the solidification process are affected by applying electromagnetic field stirring, so that the component uniformity is improved, and microscopic dendrite segregation is inhibited; on the basis, the microscopic dendrite segregation is further improved by a high-temperature homogenizing annealing process. Under the combined action of the three means, the consistency of the components of the copper alloy easy to segregate and the uniformity control of the cast structure are realized.
The technical scheme of the method for improving copper alloy segregation is as follows:
(1) The added multi-element composite rare earth element copper alloy consists of the following components in percentage by weight: 0.02-1.0% of Y, 0.02-2.0% of Ce, 0.01-0.8% of Eu, 0.01-0.5% of Rb and the balance of Cu.
Preferably, the rare earth element is added in the following amount: y0.6%, ce 0.5%, eu 0.05%, rb 0.05% and the balance Cu.
(2) Smelting: after the copper alloy is melted, adding a plurality of composite rare earth elements, wherein the total addition amount is 0.2-0.5% of the total weight of the melt, the melting temperature is 1150-1250 ℃, the melting process is realized by a charcoal covering layer in the heating and melting process under the micro-oxidation atmosphere, and a graphite stirring rod is adopted for stirring in the melting process. The added Y, eu and Rb elements react with oxygen to form Y 2 O 3 、Eu 2 O 3 、Rb 2 O 2 Wherein Eu is 2 O 3 Mainly has degassing effect, rb 2 O 2 Catalytic action in melt reaction and with Y 2 O 3 The alloy acts together with Ce to obviously refine grains, and the functions of deoxidizing, deslagging, refining grains and the like are realized through the synergistic effect of the multi-element composite rare earth.
(3) Casting: after no scum appears on the surface of the molten liquid, the molten liquid is stirred out to form a mirror surface on the surface of the molten liquid and then is stood for 1-3 minutes, and the molten liquid is directly poured into a casting mold, wherein the pouring temperature is 1200-1300 ℃. At this time, an electromagnetic field is applied to the outside of the metal casting mold, the electromagnetic stirring device is an annular device, the casting mold is arranged in the middle of the annular electromagnetic device, after the molten metal is poured into the casting mold, the external force influence is applied to the solidification process of the molten metal by adjusting the frequency or the current of the electromagnetic field, the frequency application range is 10-80Hz, and the current application range is 20-100A. Under the action of electromagnetic field, dendrite segregation is inhibited, and component uniformity is ensured.
(4) Homogenization stage: copper alloy cast ingot prepared under the combined action of rare earth alloying and electromagnetic field stirring is heated to a temperature slightly lower than the solidus temperature range for long-time heat preservation, so that microscopic dendrite segregation is further improved, and tissue and performance homogenization is realized. Adopting a two-stage homogenizing annealing process, wherein the first-stage homogenizing annealing is performed at 900-950 ℃ for 30-60min when the high temperature is short, so that the rapid solid diffusion of the easily segregated elements is realized, and coarse grains caused by the high temperature for a long time are avoided; and when the second-stage homogenizing annealing is carried out at a low temperature of 800-850 ℃ for 120-360min, the full solid diffusion is realized, and the segregation is further improved.
In the method, in the smelting stage, composite rare earth elements Y, ce, eu, rb and the like are added into the alloy to purify the melt (remove trace impurity elements), improve the fluidity of the melt and refine the size of as-cast grains; in the casting stage, dendrite formation and growth in the solidification process are affected by applying electromagnetic field stirring, so that the component uniformity is improved, and microscopic dendrite segregation is inhibited; on the basis, the microscopic dendrite segregation is further improved by a high-temperature homogenizing annealing process.
The following effects can be achieved by using the method:
(1) The alloy has uniform components and trace impurity elements controlled at lower level: o is less than or equal to 5ppm, S is less than or equal to 3ppm, and P is less than or equal to 3ppm;
(2) Eliminating shrinkage porosity, air holes and other as-cast defects;
(3) The grain size of an as-cast structure is thinned, and the average size is controlled below 20 mu m;
(4) The microscopic dendrite segregation is obviously inhibited, the dendrite spacing is controlled within 2 mu m, and dendrite distribution is uniform and orientation arrangement is consistent.
The method is particularly suitable for preparing Cu-Ni-Sn and other easily segregated copper alloy materials. Generally, the Cu-Ni-Sn alloy has a Ni content of 8-16% by mass and a Sn content of 3-9% by mass. The Cu-Ni-Sn alloy may further contain an alloying element such as Pb, for example, the Cu-Ni-Sn alloy further contains Pb, the mass content of Pb being 2 to 4%.
The following describes the practice of the invention in detail with reference to specific examples.
1. Specific examples of the method for improving segregation of copper alloy of the present invention
Example 1
The method for improving the segregation of the copper alloy in the embodiment selects a multi-element complex Cu-10Ni-4Sn-3Pb tin bronze alloy, which comprises the following components in percentage by weight: 9-11% of Ni, 3-5% of Sn, 2-4% of Pb and the balance of Cu; the method for improving the segregation of the Cu-10Ni-4Sn-3Pb tin bronze alloy comprises the following steps:
(1) Smelting: firstly, adding an electrolytic copper plate into a smelting furnace, heating to melt the electrolytic copper plate, adding a pure nickel plate after the electrolytic copper plate is completely melted, then adding multi-element composite rare earth, and finally adding pure tin and pure lead. The added multielement composite rare earth element consists of the following components in percentage by weight: y0.02%, ce 0.02%, eu 0.01%, rb 0.01% and the balance Cu. The total addition was 0.2% of the total weight of the melt. The smelting temperature is 1150 ℃, the smelting process is carried out under the micro-oxidation atmosphere by the charcoal covering layer in the heating and smelting process, and the graphite stirring rod is adopted for stirring in the smelting process.
(2) Casting: after no scum appears on the surface of the molten liquid, the molten liquid is stirred out to form a mirror surface on the surface of the molten liquid and then is stood for 1 minute, and the molten liquid is directly poured into a casting mold, wherein the pouring temperature is 1200 ℃. At this time, an electromagnetic field is applied to the outside of the metal casting mold, the electromagnetic stirring device is an annular device, the casting mold is arranged in the middle of the annular electromagnetic device, and after the molten metal is poured into the casting mold, the external force influence is applied to the solidification process of the molten metal by adjusting the frequency or the current of the electromagnetic field, the frequency application range is 10Hz, and the current application range is 20A. Under the action of electromagnetic field, dendrite segregation is inhibited, and component uniformity is provided.
(3) Homogenization stage: copper alloy cast ingot prepared under the combined action of rare earth alloying and electromagnetic field stirring is heated to a temperature slightly lower than the solidus temperature range for long-time heat preservation, so that microscopic dendrite segregation is further improved, and tissue and performance homogenization is realized. Adopting a two-stage homogenizing annealing process, wherein the first-stage homogenizing annealing is performed at a high temperature of 900 ℃ for a short time, the heating speed is 20 ℃/min, the heat preservation time is 60min, the cooling mode is air cooling, the rapid solid diffusion of the easily segregated elements is realized, and coarse grains caused by the high temperature for a long time are avoided; and when the second-stage homogenizing annealing is carried out at a low temperature, the temperature is 800 ℃, the heating speed is 10 ℃ per minute, the heat preservation time is 360 minutes, and the cooling mode is cooling along with the furnace, so that sufficient solid diffusion is realized, and the segregation is further improved.
The complex Cu-10Ni-4Sn-3Pb tin bronze alloy prepared in the embodiment: (1) The alloy has uniform components and trace impurity elements controlled at lower level: o content 4ppm, S content 3ppm, P content 3ppm; (2) eliminating shrinkage porosity, air holes and other as-cast defects; (3) The grain size of an as-cast structure is thinned, and the average grain size is controlled to be 18 mu m; (4) The microscopic dendrite segregation is obviously inhibited, the dendrite spacing is controlled within 2 mu m, and dendrite distribution is uniform and orientation arrangement is consistent.
Example 2
The method for improving the segregation of the copper alloy in the embodiment selects a multi-element complex Cu-9Ni-6Sn alloy, which consists of the following components in percentage by weight: 8-10% of Ni, 5-7% of Sn and the balance of Cu; the specific method comprises the following steps:
(1) Smelting: firstly, adding an electrolytic copper plate into a smelting furnace, heating to melt the electrolytic copper plate, adding a pure nickel plate after the electrolytic copper plate is completely melted, then adding multi-element composite rare earth, and finally adding pure tin and pure lead. The added multielement composite rare earth element mainly comprises the following components in percentage by weight: y1.0%, ce 2.0%, eu 0.8%, rb 0.5%, and the balance Cu. The total addition was 0.5% of the total weight of the melt. The smelting temperature is 1250 ℃, the melting process is realized by a charcoal covering layer in the heating and melting process, and the graphite stirring rod is adopted for stirring in the smelting process.
(2) Casting: after no scum appears on the surface of the molten liquid, the molten liquid is stirred out to form a mirror surface on the surface of the molten liquid and then is stood for 2 minutes, and the molten liquid is directly poured into a casting mold, wherein the pouring temperature is 1300 ℃. At this time, an electromagnetic field is applied to the outside of the metal casting mold, the electromagnetic stirring device is an annular device, the casting mold is arranged in the middle of the annular electromagnetic device, and after the molten metal is poured into the casting mold, the external force influence is applied to the solidification process of the molten metal by adjusting the frequency or the current of the electromagnetic field, the frequency application range is 80Hz, and the current application range is 100A. Under the action of electromagnetic field, dendrite segregation is inhibited, and component uniformity is provided.
(3) Homogenization stage: copper alloy cast ingot prepared under the combined action of rare earth alloying and electromagnetic field stirring is heated to a temperature slightly lower than the solidus temperature range for long-time heat preservation, so that microscopic dendrite segregation is further improved, and tissue and performance homogenization is realized. Adopting a two-stage homogenizing annealing process, wherein the first-stage homogenizing annealing is performed at a high temperature of 950 ℃ for a short time, the temperature rising speed is 20 ℃/min, the heat preservation time is 30min, the cooling mode is air cooling, the rapid solid diffusion of the easily segregated elements is realized, and coarse grains caused by the high temperature for a long time are avoided; and when the second-stage homogenizing annealing is carried out at a low temperature, the temperature is 850 ℃, the heating speed is 10 ℃ per minute, the heat preservation time is 120 minutes, and the cooling mode is cooling along with the furnace, so that sufficient solid diffusion is realized, and the segregation is further improved.
The complex Cu-9Ni-6Sn alloy prepared in the embodiment: (1) The alloy has uniform components and trace impurity elements controlled at lower level: o content 4ppm, S content 3ppm, P content 3ppm; (2) eliminating shrinkage porosity, air holes and other as-cast defects; (3) The grain size of an as-cast structure is thinned, and the average grain size is controlled to be 17 mu m; (4) The microscopic dendrite segregation is obviously inhibited, the dendrite spacing is controlled within 2 mu m, and dendrite distribution is uniform and orientation arrangement is consistent.
Example 3
The method for improving the segregation of the copper alloy in the embodiment selects a multi-element complex Cu-15Ni-8Sn alloy, which consists of the following components in percentage by weight: 14-16% of Ni, 7-9% of Sn and the balance of Cu. The segregation improvement method for the copper alloy comprises the following steps:
(1) Smelting: firstly, adding an electrolytic copper plate into a smelting furnace, heating to melt the electrolytic copper plate, adding a pure nickel plate after the electrolytic copper plate is completely melted, then adding multi-element composite rare earth, and finally adding pure tin and pure lead. The added multielement composite rare earth element mainly comprises the following components in percentage by weight: y0.6%, ce 0.5%, eu 0.05%, rb 0.05% and the balance Cu. The total addition was 0.3% of the total weight of the melt. The smelting temperature is 1200 ℃, the melting process is realized by a charcoal covering layer in the heating and melting process, and the graphite stirring rod is adopted for stirring in the smelting process.
(2) Casting: after no scum appears on the surface of the molten liquid, the molten liquid is stirred out to form a mirror surface on the surface of the molten liquid and then is stood for 3 minutes, and the molten liquid is directly poured into a casting mold, wherein the pouring temperature is 1250 ℃. At this time, an electromagnetic field is applied to the outside of the metal casting mold, the electromagnetic stirring device is an annular device, the casting mold is arranged in the middle of the annular electromagnetic device, and after the molten metal is poured into the casting mold, the external force influence is applied to the solidification process of the molten metal by adjusting the frequency or the current of the electromagnetic field, the frequency application range is 40Hz, and the current application range is 50A. Under the action of electromagnetic field, dendrite segregation is inhibited, and component uniformity is provided.
(3) Homogenization stage: copper alloy cast ingot prepared under the combined action of rare earth alloying and electromagnetic field stirring is heated to a temperature slightly lower than the solidus temperature range for long-time heat preservation, so that microscopic dendrite segregation is further improved, and tissue and performance homogenization is realized. Adopting a two-stage homogenizing annealing process, wherein the first-stage homogenizing annealing is performed at a high temperature of 920 ℃ for a short time, the temperature rising speed is 20 ℃/min, the heat preservation time is 35min, the cooling mode is air cooling, the rapid solid diffusion of the easily segregated elements is realized, and coarse grains caused by the high temperature for a long time are avoided; and when the second-stage homogenizing annealing is carried out at a low temperature, the temperature is 820 ℃, the heating speed is 10 ℃ per minute, the heat preservation time is 240 minutes, and the cooling mode is cooling along with the furnace, so that sufficient solid diffusion is realized, and the segregation is further improved.
Cu-15Ni-8Sn alloy prepared in this example: (1) The alloy has uniform components and trace impurity elements controlled at lower level: 3ppm of O, 3ppm of S and 3ppm of P; (2) eliminating shrinkage porosity, air holes and other as-cast defects; (3) The grain size of an as-cast structure is thinned, and the average grain size is controlled to be 15 mu m; (4) The microscopic dendrite segregation is obviously inhibited, the dendrite spacing is controlled within 1.5 mu m, and dendrite distribution is uniform and orientation arrangement is consistent.
2. Experimental example
The Cu-10Ni-4Sn-3Pb tin bronze alloy prepared in example 1 was subjected to a corrosion test, and the corrosion method was as follows: sequentially polishing the selected samples with sand paper with different granularity of 600 meshes, 800 meshes, 1000 meshes and 1500 meshes, polishing the surfaces of the samples on a polishing machine until the surfaces of the samples are mirror surfaces and have no scratch sundries, and then corroding the samples, wherein FeCl is adopted as a corrosive agent 3 (10g)+HCl(10ml)+H 2 O (100 ml), and a macroscopic corrosion structure view of the corroded sample is shown in FIG. 1. As can be seen from FIG. 1, the structure grains are obviously thinned in the mode, and the whole section structure consists of uniform and fine equiaxed grains, and the grain size grade reaches the grade 10 of superfine grains.
The microstructure of the Cu-10Ni-4Sn-3Pb tin bronze alloy prepared in example 1 was observed, and the results are shown in FIG. 2. As can be seen from fig. 2, primary dendrite arms in the alloy microstructure are obviously broken, the orientation distribution is more uniform, the secondary dendrite arm distance is finer, the distribution of elemental lead quality points is more uniformly dispersed, and the overall segregation condition is obviously improved.
3. Comparative example
Comparative examples 1 to 3 are comparative examples corresponding to examples 1 to 3, respectively, to which different composite rare earth elements were added. Unless otherwise specified, only the addition form of the composite rare earth element is different.
Comparative example 1
The multielement complex Cu-10Ni-4Sn-3Pb tin bronze alloy prepared in the comparative example comprises the following components in percentage by weight: eu 0.01%, rb 0.01%, and the balance Cu. The total addition was 0.2% of the total weight of the melt.
In contrast to example 1, the alloy prepared in this comparative example: (1) trace impurity elements: o content 10ppm, S content 8ppm, P content 8ppm; (2) The grain size of the cast structure is obviously increased due to the deficiency of Y and Ce, and the average grain size is 65 mu m; (3) The macro-component segregation and the micro dendrite segregation are serious, the primary dendrite arms are continuously distributed, and the dendrite spacing of the secondary dendrite arms is more than 10 mu m.
Comparative example 2
The multielement complex Cu-9Ni-6Sn alloy prepared in the comparative example comprises the following components in percentage by weight: y1.0%, ce 2.0%, rb 0.5%, and Cu in balance. The total addition was 0.5% of the total weight of the melt.
In contrast to example 2, the alloy prepared in this comparative example: (1) trace impurity elements: o content 7ppm, S content 5ppm, P content 5ppm; (2) Due to the loss of Eu element, more shrinkage porosity, air holes and other as-cast defects exist; (3) The size of the crystal grains of the cast structure is increased, and the average crystal grain size is 25 mu m; (4) The macro-component segregation and the micro dendrite segregation are serious, the primary dendrite arms are continuously distributed, and the dendrite spacing of the secondary dendrite arms is larger than 6 mu m.
Comparative example 3
The multielement complex Cu-15Ni-8Sn alloy prepared in the comparative example comprises the following components in percentage by weight: y0.6%, ce 0.5%, eu 0.05%, and the balance Cu. The total addition was 0.3% of the total weight of the melt.
In contrast to example 3, the alloy prepared in this comparative example: (1) trace impurity elements: o content 10ppm, S content 8ppm, P content 8ppm; (2) As Rb element is absent, more as-cast defects such as inclusion exist; (3) The size of the crystal grain of the cast structure is increased, and the average crystal grain size is 36 mu m; (4) The macro-component segregation and the micro dendrite segregation are serious, the primary dendrite arms are continuously distributed, and the dendrite spacing of the secondary dendrite arms is larger than 8 mu m.
Comparative examples 4 to 6 are comparative examples of different homogenization annealing systems corresponding to examples 1 to 3, respectively. Unless otherwise indicated, only the homogenization annealing regime is different.
Comparative example 4
The multi-element complex Cu-10Ni-4Sn-3Pb tin bronze alloy prepared in comparative example 1 adopts a conventional homogenizing annealing process: the homogenizing annealing temperature is 850 ℃, the heating speed is 15 ℃/min, the heat preservation time is 480min, and the cooling mode is air cooling.
In contrast to example 1, the alloy prepared in this comparative example: (1) The size of the crystal grain of the cast structure is obviously increased, and the average crystal grain size is 70 mu m; (2) The macro-component segregation and the micro dendrite segregation are serious, the primary dendrite arms are continuously distributed and are disordered in orientation, and the dendrite spacing of the secondary dendrite arms is larger than 12 mu m.
Comparative example 5
The multi-element complex Cu-9Ni-6Sn alloy prepared in comparative example 2 adopts a conventional homogenizing annealing process: the homogenizing annealing temperature is 900 ℃, the heating speed is 20 ℃/min, the heat preservation time is 360min, and the cooling mode is air cooling.
In contrast to example 2, the alloy prepared in this comparative example: (1) The size of the crystal grain of the cast structure is obviously increased, and the average crystal grain size is 85 mu m; (2) The macro-component segregation and the micro dendrite segregation are serious, the primary dendrite arms are continuously distributed and are disordered in orientation, and the dendrite spacing of the secondary dendrite arms is larger than 11 mu m.
Comparative example 6
The multi-element complex Cu-15Ni-8Sn alloy prepared in comparative example 3 adopts a conventional homogenizing annealing process: the homogenizing annealing temperature is 820 ℃, the heating speed is 10 ℃/min, the heat preservation time is 600min, and the cooling mode is air cooling.
In contrast to example 3, the alloy prepared in this comparative example: (1) The size of the crystal grain of the cast structure is obviously increased, and the average crystal grain size is 65 mu m; (2) The macro-component segregation and the micro dendrite segregation are serious, the primary dendrite arms are continuously distributed and are disordered in orientation, and the dendrite spacing of the secondary dendrite arms is larger than 10 mu m.

Claims (8)

1. A method for improving copper alloy segregation, which is characterized by comprising the step of carrying out two-stage homogenizing annealing on a copper alloy cast ingot; wherein the temperature of the first-stage homogenizing annealing is 900-950 ℃ for 30-60min, the temperature of the second-stage homogenizing annealing is 800-850 ℃ for 120-360min.
2. The method for improving copper alloy segregation according to claim 1, wherein the copper alloy ingot is cast from a molten metal, the molten metal is obtained by adding a composite rare earth element to a copper alloy raw material, and the composite rare earth element is formed by smelting Y, ce, eu and Rb, and the weight ratio of Y, ce, eu, rb is (0.02-1.0): (0.02-2.0): (0.01-0.8): (0.01-0.5).
3. The method for improving segregation of copper alloy according to claim 2, wherein the mass ratio of the Y element in the molten metal is 0.004-0.5%.
4. The method for improving copper alloy segregation according to claim 2, wherein the composite rare earth element is added in the form of a composite rare earth element copper alloy composed of the following components in mass fraction: 0.02-1.0% of Y, 0.02-2.0% of Ce, 0.01-0.8% of Eu, 0.01-0.5% of Rb and the balance of Cu; the addition amount of the composite rare earth element copper alloy is 0.2-0.5% of the metal melt.
5. The method for improving copper alloy segregation according to any one of claims 2 to 4, wherein the smelting temperature is 1150 ℃ to 1250 ℃.
6. The method for improving segregation of copper alloy according to claim 1, wherein electromagnetic stirring is applied when the molten metal is solidified.
7. The method for improving segregation of copper alloy according to claim 6, wherein the electromagnetic field applied with electromagnetic stirring has a frequency of 10 to 80Hz and a current of 20 to 100A.
8. The method for improving segregation of a copper alloy according to claim 1, 2 or 6, wherein the copper alloy is a Cu-Ni-Sn alloy.
CN202310090540.2A 2023-02-09 2023-02-09 Method for improving copper alloy segregation Pending CN116043150A (en)

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