A high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material, its preparation method, and its application.

Abstract

This invention discloses a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material, its preparation method, and its applications. Based on the Cu-Cr-Zr alloy, elements such as Fe, Si, Mg, Zn, Sn, Nb, Ag, and Ti are added, causing the alloy to form submicron-scale heat-resistant strengthening phases, such as Cr3Si and Cr2Nb, during solidification. This also improves the high-temperature stability of the dispersed nanoscale Cr-rich phase precipitated during aging. Through the combined action of multiple strengthening mechanisms, including multiphase synergistic dispersion strengthening, strain strengthening, subgrain strengthening, and solid solution strengthening, the alloy exhibits high hardness, high strength, high conductivity, high softening temperature, and excellent high-temperature performance, making it suitable for use in resistance spot welding electrodes.

Description

Technical Field

[0001] This invention belongs to the field of new copper alloy materials technology, specifically relating to a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material, its preparation method, and its application. Background Technology

[0002] Cu-Cr-Zr alloys are a class of high-strength, high-conductivity copper alloys that have attracted considerable attention. They can be applied in fields such as integrated circuit lead frames, resistance welding electrodes, overhead conductors for electric locomotives, and thrust chamber wall materials for rocket engines. In various complex environments, Cu-Cr-Zr alloys often play a role in controlling circuit transmission while bearing pressure and resisting wear. This process is often accompanied by a large amount of Joule heating, arc burning, and material transfer, which seriously affects the lifespan and performance of Cu-Cr-Zr alloy materials.

[0003] Taking resistance spot welding electrode materials as an example, the main functions of the electrode during the welding process are to transmit current and pressure, as well as dissipate heat. During welding, the electrode needs to conduct current densities of hundreds or even thousands of amperes per square millimeter, transmit electrode pressures exceeding 100 MPa, and simultaneously conduct the heat generated during welding. This requires not only high electrical and thermal conductivity but also excellent high-temperature softening resistance and high-temperature strength. Currently, most Cu-Cr-Zr electrodes in service have a conductivity of 70–80% IACS, a hardness of 140–170 HV, and a softening temperature of 500℃–550℃. Although their lifespan can reach over 50,000 weld points when spot welding uncoated cold-rolled steel sheets, when welding coated steel sheets or multi-layered steel sheet weldments, Cu-Cr-Zr electrodes are prone to problems such as electrode tip alloying, plastic deformation, and adhesion, reducing their lifespan to only about 1 / 100th that of welding ordinary low-carbon steel sheets, significantly reducing production efficiency. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the first objective of this invention is to provide a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material.

[0005] The second objective of this invention is to provide a method for preparing high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy materials.

[0006] The third objective of this invention is to provide an application of a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material. The Cu-Cr-Zr alloy material, by mass percentage, has the following composition: Cr: 0.8–2.5%, Zr: 0.05–0.2%, Fe: 0–0.2%, Si: 0–0.1%, Mg: 0–0.2%, Zn: 0.05–0.3%, Sn: 0–0.2%, Nb: 0–0.2%, Ag: 0–0.2%, Ti: 0–0.1%, with the balance being Cu. The total mass percentage of Fe, Si, Mg, Zn, Sn, Nb, Ag, and Ti is <0.5%.

[0009] In a preferred embodiment, the Cu-Cr-Zr alloy material has the following composition by mass percentage: Cr: 0.9–2.5%, Zr: 0.05–0.2%, Fe: 0.01–0.2%, Si: 0.01–0.1%, Mg: 0.01–0.2%, Zn: 0.05–0.3%, Sn: 0.01–0.2%, Nb: 0.01–0.2%, Ag: 0.01–0.2%, Ti: 0.01–0.1%, with the balance being Cu.

[0010] This invention provides a Cu-Cr-Zr alloy material for use as a resistance welding electrode. During the welding process, resistance welding electrodes need to conduct currents of hundreds or even thousands of amperes per square millimeter, withstand electrode pressures exceeding 100 MPa, and simultaneously conduct the heat generated during welding. This requires the material to possess not only high electrical and thermal conductivity, but also excellent arc-extinguishing properties, resistance to high-temperature softening, and high-temperature strength. Therefore, this invention first adds a relatively high content of Cr (greater than the maximum solid solubility of Cr in Cu) to improve the arc-quenching performance of the material (Cr has strong gas absorption properties at high temperatures) and the high-temperature deformation resistance (undissolved Cr elements form heat-resistant primary phases that pin grain boundary movement). Furthermore, trace amounts of Fe, Si, Nb, Ti, and Mg elements can precipitate along with Cr atoms during aging and agglomerate within or on the surface of the Cr-rich precipitates, forming more stable coherent precipitates that hinder further growth of the precipitates at high temperatures. This refines the precipitate size and enhances the precipitation strengthening effect of the alloy. While maintaining high conductivity in the Cu-Cr-Zr alloy, this improves the overall strength and heat resistance of the alloy material at both room and high temperatures. The trace amounts of Si and Nb elements can also combine with Cr during solidification to form thermally stable hard phases, such as Cr3Si and Cr2Nb. These hard particles are broken and refined during processing and deformation, becoming the nuclei for recrystallization and further refining the grain size. Furthermore, these fine, hard phase particles distributed around grain boundaries facilitate grain boundary pinning, reduce grain boundary mobility, and thus improve grain boundary stability. This is beneficial for improving the alloy's resistance to deformation and tensile properties at both room and high temperatures. The trace addition of Ag and Zn elements has minimal impact on the electrical conductivity of copper alloys and will not significantly reduce it. The uniform solid solution of Ag and Zn in the copper matrix provides solid solution strengthening without significantly reducing conductivity, and their existence is not easily affected by the aging process. This reduces the stacking fault energy of the alloy, hinders the interaction between dislocations, retains a higher dislocation density and more substructures in the alloy matrix, and improves the alloy's recrystallization temperature and resistance to softening.

[0011] With the synergistic effect of the above components, the Cu-Cr-Zr alloy material of the present invention has high hardness, high strength, high conductivity, high softening temperature, high temperature performance, and excellent arc extinguishing performance, and can be widely used in resistance spot welding electrodes.

[0012] In this invention, the effective synergistic effect is achieved only when the content of each element is controlled within the specified range. For example, insufficient Cr content cannot meet the requirements for arc extinguishing performance and high-temperature deformation resistance of resistance welding electrode materials. Conversely, excessive Cr content leads to an increase in the size of the Cr-rich primary phase in the Cu matrix, which has limited effect on improving material strength and is also detrimental to the finishing process of resistance welding electrode caps (hard particles may detach during the grinding process). Furthermore, Cu alloys with high Cr content are difficult to prepare using existing non-vacuum melting methods and are generally suitable for powder metallurgy. In addition to Cr, Zr has the most significant effect on improving the performance of alloy materials. Adding Zr to Cu-Cr alloys can cause Zr to segregate on the surface of the precipitated Cr phase through aging treatment, inhibiting the coarsening of the Cr phase and further improving the alloy's resistance to high-temperature softening. However, adding too much will reduce the conductivity of the alloy; and Fe, Si, Mg, Zn, Sn, Nb, Ag, and Ti are trace elements and should not be added in excess, especially Fe, Si, and Ti, as excessive amounts will drastically reduce the conductivity of Cu alloys. However, the addition of trace amounts within the scope of this invention can exist in the form of a heat-resistant second phase or precipitate together with the Cr-rich precipitate phase, thereby avoiding solid solution in the Cu matrix (the solid solution form has the greatest impact on the conductivity of Cu alloys).

[0013] In a further preferred embodiment, the Cu-Cr-Zr alloy material has the following composition by mass percentage: Cr: 1.1-1.8%, Zr: 0.05-0.1%, Fe: 0.03-0.05%, Si: 0.01-0.05%, Mg: 0.01-0.05%, Zn: 0.1-0.2%, Sn: 0.01%, Nb: 0.01-0.1%, Ag: 0.01%, Ti: 0.01%, with the balance being Cu.

[0014] This invention provides a method for preparing a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material. The method involves mixing various metal raw materials according to a designed ratio and performing non-vacuum melting to obtain an ingot. The ingot is then homogenized to obtain a billet. The billet is then hot-worked to obtain a bar. The bar is then subjected to solution treatment, pre-aging treatment, a first cold working, a first aging, a second cold working, and a second aging to obtain the Cu-Cr-Zr alloy material.

[0015] The preparation method of this invention first uses non-vacuum melting to obtain Cu-Cr-Zr alloy material with high Cr content. Then, the ingot is homogenized to eliminate as-cast segregation and achieve a certain solid solution effect. After hot working to obtain the bar, solid solution treatment is performed to allow Cr and other micro-alloying elements to fully dissolve in the Cu matrix. Finally, in the subsequent deformation heat treatment process, the process applies the precipitation motive force of alloying elements through processing deformation and aging heat treatment. Through high-frequency forging, high-efficiency strain and other methods, the alloy bar obtains a fiber-reinforced structure along the length direction.

[0016] The above preparation method enables the high-Cr-rich phase to serve as the primary reinforcing second phase, resulting in a multi-scale phase synergistic strengthening effect. On one hand, Cr dissolved in the Cu matrix precipitates during deformation heat treatment, suppressing coarsening at high temperatures and improving the thermal stability of the nanoscale precipitate phase under the influence of additive elements. On the other hand, Cr not dissolved in the Cu matrix forms micron- and submicron-scale heat-resistant primary phases with additive elements, which can exist stably at high temperatures and pin grain boundary movement. Ultimately, the resulting Cu-Cr-Zr alloy material exhibits good elongation, excellent softening resistance, and high-temperature performance. The good elongation corresponds to good processing performance, which is beneficial for the grinding process of resistance welding electrode caps during service. The excellent softening resistance and high-temperature performance enable the Cu-Cr-Zr alloy material to withstand Joule heat generated by high current density, thus improving its service life.

[0017] The preferred method involves preparing pure copper, Cu-Cr master alloy, Cu-Zr master alloy, Cu-Nb master alloy, Cu-Ti master alloy, pure Fe, pure Si, pure Mg, pure Sn, pure Ag, and pure Zn according to the designed proportions. First, the pure copper is melted, and then the temperature is raised to 1200–1300℃. Pure Fe, pure Ag, pure Zn, and pure Sn are added, and the temperature is further raised to 1300–1400℃. Cu-Cr master alloy is added in 3–4 batches, and the mixture is held at this temperature for 2–3 minutes and then stirred for 30–60 seconds. Subsequently, Cu-Nb master alloy, Cu-Ti master alloy, pure Si, pure Mg, and Cu-Zr master alloy are added, and the mixture is held at this temperature for 1–2 minutes. Then, the temperature is lowered to 1100℃–1200℃ while stirring, and finally, the mixture is cast.

[0018] Non-vacuum melting can significantly reduce melting costs and facilitate large-scale industrial production. However, chromium has a solid solubility of only 0.8% in the Cu matrix. In this invention, to improve the arc-quenching performance of the material, more than 0.8% Cr is added. However, Cr exceeding the maximum solid solubility significantly increases the difficulty of melting this alloy, as the melt viscosity increases and slag formation is more likely. Furthermore, the Zr element in this invention is also highly reactive and easily burned off, further complicating non-vacuum melting, making compositional stabilization difficult, and resulting in poor performance consistency. Therefore, this invention… The invention utilizes pure Fe, pure Si, pure Mg, pure Sn, and pure Ag as deoxidizers and refining agents in the non-vacuum melting process of Cu alloys. By generating high-melting-point compounds at high temperatures, these agents remove oxygen, phosphorus, and sulfur elements from the melt, thereby improving melt fluidity, purifying the melt, and ultimately enhancing the quality of Cu alloy billets. More importantly, the invention employs a clever design, adjusting the order of addition of different materials, and adding the Cu-Cr master alloy in batches. Simultaneously, stirring the melt after adding the Cu-Cr master alloy effectively reduces burn-off.

[0019] The inventors discovered that the timing of stirring is crucial. Stirring the melt after adding the Cu-Cr master alloy effectively reduces burn-off. This is because it facilitates thorough stirring and reduces the cooling effect of the added material on the melt, preventing a sudden drop in temperature and ensuring the Cu-Cr master alloy melts completely. Stirring significantly reduces the high-temperature burn-off rate, ultimately resulting in a uniform Cr composition distribution in the ingot, comparable to powder metallurgy products. However, continuous stirring during smelting actually increases the burn-off rate. This is because continuous stirring easily leads to heat loss, making it difficult to maintain the temperature, and it also accelerates the contact between the melt and oxygen, increasing the burn-off rate. This invention, by performing short-term stirring after heat preservation and when the melt has good fluidity, can improve compositional uniformity while ensuring stable composition control and avoiding burn-off.

[0020] In a further preferred embodiment, the mass fraction of Cr in the Cu-Cr master alloy is ≤20%, preferably 10-20%.

[0021] In a further preferred embodiment, the Cu-Zr master alloy has a Zr mass fraction of ≤50%, preferably 30-50%.

[0022] In a further preferred embodiment, the mass fraction of Nb in the Cu-Nb master alloy is ≤5%, preferably 3-5%.

[0023] In a further preferred embodiment, the Cu-Ti master alloy has a Ti mass fraction of ≤60%, preferably 40-60%.

[0024] The inventors discovered that by using an intermediate alloy with the above-mentioned composition, the burn-off rate of each metal can be minimized, and alloy ingots with the designed composition can be obtained.

[0025] Further preferably, the pure copper is electrolytic copper, and the purity of the pure copper is ≥99.95 wt.%, the purity of pure Fe is ≥99.95 wt.%, the purity of pure Si is ≥99.95 wt.%, the purity of pure Mg is ≥99.95 wt.%, the purity of pure Sn is ≥99.95 wt.%, and the purity of pure Ag is ≥99.95 wt.%.

[0026] In a further preferred embodiment, the temperature of the non-vacuum melting is 1200–1500°C. Controlling the temperature of the non-vacuum melting within the above range can completely melt high-melting-point raw materials while avoiding the loss of low-melting-point and easily burnable elements.

[0027] In a further preferred embodiment, the stirring method is mechanical uniform stirring, with a stirring rate of 60-100 r / min, and the stirring head used for stirring is made of graphite.

[0028] The inventors discovered that controlling the stirring rate within the above range is the most effective way to reduce burn-off. If the stirring rate is too slow, it will not be effective, while if it is too fast, it may cause molten material to splash or damage the graphite stirring head.

[0029] In a preferred embodiment, during the non-vacuum melting process, the melt is coated with graphite. This graphite coating reduces the burn-off rate.

[0030] In a preferred embodiment, the melt temperature is reduced to 1100℃~1200℃, and then poured into a mold preheated to 400℃~500℃ to obtain an ingot.

[0031] Further optimization involves ensuring that the casting time, starting from the Cu-Cr master alloy in the non-vacuum melting process, is ≤10 minutes.

[0032] In a preferred embodiment, the homogenization treatment temperature is 900-1000℃, the homogenization treatment time is 2h-4h, and the billet is obtained by water quenching after the homogenization treatment is completed.

[0033] The homogenization process of this invention employs a higher homogenization temperature compared to conventional Cu-Cr-Zr alloys. The purpose of homogenization is to eliminate as-cast segregation and achieve a certain solid solution effect. The alloy material in this patent inherently possesses good heat resistance, and its Cr content already exceeds the maximum solid solubility, requiring a higher homogenization temperature and a longer homogenization time to achieve microstructure homogenization and solid solution effects. However, if the homogenization temperature is too high and the homogenization time is too long, on the one hand, the alloy grains grow rapidly during homogenization, resulting in a sharp decrease in strength; on the other hand, it also increases the cost of the heat treatment process.

[0034] In actual operation, after homogenization, defects on the surface of the ingot are removed and corrected by machining; after machining, it is necessary to ensure that the surface of the ingot is free of oxide layer, shrinkage cavities and internal holes.

[0035] In a preferred embodiment, the hot working is selected from hot extrusion or hot forging, the holding temperature before hot working is 900-1000℃, the holding time is 1-2h, the hot working deformation is 50%-80%, and the hot working is followed by water quenching.

[0036] In a preferred embodiment, the solution treatment temperature is 940–1000℃, the solution treatment time is 2–4 hours, and water quenching is performed after the solution treatment is completed. The solution temperature is also higher than that used for conventional Cu-Cr-Zr alloys, thereby achieving a better solution treatment effect.

[0037] In a preferred embodiment, the pre-aging temperature is 400-500℃ and the pre-aging time is 30-120 min.

[0038] The inventors discovered that by performing an aging treatment before deformation, the Cr-rich phase can precipitate more fully, resulting in a more significant precipitation strengthening effect. After solution treatment, the material has a certain precipitation motive force, and a pre-aging process can be adopted to allow some of the Cr-rich phase to precipitate in advance. Finally, by combining continuous deformation and aging treatment, a better precipitation effect can be obtained.

[0039] In a preferred embodiment, the primary cold working is cold rotary forging or cold hole rolling, and the deformation amount of the primary cold working is 50% to 80%.

[0040] The inventors discovered that by using rotary forging, high-density dislocations can be introduced through high-frequency forging, which can more effectively break the matrix grains and make the work hardening effect of the material more obvious. Furthermore, the high operability of the roll pass makes it more conducive to improving the efficiency of mass production.

[0041] In a preferred embodiment, the temperature of the first aging is 400℃~500℃, the aging time is 30min~300min, and water quenching is performed after the first aging.

[0042] The inventors discovered that controlling the aging temperature within the aforementioned range results in optimal material performance. If the aging temperature is too low, the precipitation motive force is insufficient, Cr cannot precipitate effectively, and the material's conductivity and strength cannot reach excellent levels after aging. Conversely, if the aging temperature is too high, recrystallization and grain growth occur before the solid solution elements have fully precipitated, leading to a sharp decline in work hardening and grain boundary strengthening effects, which cannot be compensated for by precipitation strengthening.

[0043] In a preferred embodiment, the secondary cold working is cold rotary forging or cold hole rolling, and the deformation amount of the secondary cold working is 50% to 80%.

[0044] In a preferred embodiment, the temperature of the secondary aging is 400℃~500℃, the time of the secondary aging is 30min~300min, and the secondary aging is followed by water quenching.

[0045] The third objective of this invention is to provide an application of a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material, which is used to prepare resistance spot welding electrodes.

[0046] Principles and advantages

[0047] Currently, the automotive industry extensively uses coated steel sheets and aluminum alloy sheets to improve the corrosion resistance of car bodies. A single car body has 4,000-5,000 welding points. If traditional Cu-Cr-Zr electrodes are used for welding, it will inevitably lead to rapid electrode wear and frequent replacement, directly resulting in resource waste and reduced production efficiency. This invention, from the perspectives of improving service performance, simplifying production processes, reducing production costs, saving energy, and reducing pollution, provides a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material to meet the application requirements of new resistance welding electrode materials. This material has high strength, high conductivity, and good heat resistance, which can meet the current application requirements of resistance spot welding electrode materials and extend service life.

[0048] This invention provides a Cu-Cr-Zr alloy material for use as a resistance welding electrode. During the welding process, resistance welding electrodes need to conduct currents of hundreds or even thousands of amperes per square millimeter, withstand electrode pressures exceeding 100 MPa, and simultaneously conduct the heat generated during welding. This requires the material to possess not only high electrical and thermal conductivity, but also excellent arc-extinguishing properties, resistance to high-temperature softening, and high-temperature strength. Therefore, this invention first adds a relatively high content of Cr (greater than the maximum solid solubility of Cr in Cu) to improve the arc-quenching performance of the material (Cr has strong gas absorption properties at high temperatures) and the high-temperature deformation resistance (undissolved Cr elements form heat-resistant primary phases that pin grain boundary movement). Furthermore, trace amounts of Fe, Si, Nb, Ti, and Mg elements can precipitate along with Cr atoms during aging and agglomerate within or on the surface of the Cr-rich precipitates, forming more stable coherent precipitates that hinder further growth of the precipitates at high temperatures. This refines the precipitate size and enhances the precipitation strengthening effect of the alloy. While maintaining high conductivity in the Cu-Cr-Zr alloy, this improves the overall strength and heat resistance of the alloy material at both room and high temperatures. The trace amounts of Si and Nb elements can also combine with Cr during solidification to form thermally stable hard phases, such as Cr3Si and Cr2Nb. These hard particles are broken and refined during processing and deformation, becoming the nuclei for recrystallization and further refining the grain size. Furthermore, these fine, hard phase particles distributed around grain boundaries facilitate grain boundary pinning, reduce grain boundary mobility, and thus improve grain boundary stability. This is beneficial for improving the alloy's resistance to deformation and tensile properties at both room and high temperatures. The trace addition of Ag and Zn elements has minimal impact on the electrical conductivity of copper alloys and will not significantly reduce it. The uniform solid solution of Ag and Zn in the copper matrix can achieve solid solution strengthening without significantly reducing conductivity, and their existence is not easily affected by the aging process. It can reduce the stacking fault energy of the alloy, hinder the interaction between dislocations, retain a higher dislocation density and more substructures in the alloy matrix, and improve the alloy's recrystallization temperature and resistance to softening.

[0049] With the synergistic effect of the above components, the Cu-Cr-Zr alloy material of the present invention has high hardness, high strength, high conductivity, high softening temperature, high temperature performance, and excellent arc extinguishing performance, and can be widely used in resistance spot welding electrodes.

[0050] The preparation method of this invention first uses non-vacuum melting to obtain Cu-Cr-Zr alloy material with high Cr content. Then, the ingot is homogenized to eliminate as-cast segregation and achieve a certain solid solution effect. After hot working to obtain the bar, solid solution treatment is performed to allow Cr and other micro-alloying elements to fully dissolve in the Cu matrix. Finally, in the subsequent deformation heat treatment process, the process applies the precipitation motive force of alloying elements through processing deformation and aging heat treatment. Through high-frequency forging, high-efficiency strain and other methods, the alloy bar obtains a fiber-reinforced structure along the length direction.

[0051] The preparation method of this invention enables a high-Cr-rich phase to serve as the primary reinforcing second phase, resulting in a multi-scale phase synergistic strengthening effect. On one hand, Cr dissolved in the Cu matrix precipitates during deformation heat treatment, suppressing coarsening at high temperatures under the influence of added elements and improving the thermal stability of the nanoscale precipitated phase. On the other hand, Cr not dissolved in the Cu matrix forms micron- and submicron-scale heat-resistant primary phases with added elements, which can exist stably at high temperatures and pin grain boundary movement. Ultimately, the resulting Cu-Cr-Zr alloy material exhibits good elongation, excellent softening resistance, and high-temperature performance. The good elongation corresponds to good processing performance, which is beneficial for the grinding process of resistance welding electrode caps during service. The excellent softening resistance and high-temperature performance enable the Cu-Cr-Zr alloy material to withstand Joule heat generated by high current density, thus improving its service life.

[0052] Compared with existing technologies, the above solution has the following advantages:

[0053] The high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material of the present invention is composed of trace amounts of one or more of Fe, Si, Mg, Zn, Nb, Ag, and Ti elements added to the traditional Cu-Cr-Zr. It has the characteristics of high hardness, high strength, high conductivity, high softening temperature, and excellent high-temperature performance, and can be widely used in resistance spot welding electrodes.

[0054] In the high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material of this invention, Zr is highly reactive and easily burned off, leading to difficulties in non-vacuum melting, challenges in controlling compositional stabilization, and consequently, poor performance consistency. However, the addition of Fe, Si, Mg, Zn, Nb, Ag, and Ti elements in this invention acts as deoxidizers and refining agents during the non-vacuum melting process of Cu alloys. By generating high-melting-point compounds at high temperatures, these elements remove oxygen, phosphorus, and sulfur from the melt, improving melt flowability, purifying the melt, and thus enhancing the quality of Cu alloy billets.

[0055] In the high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material of this invention, trace amounts of Fe, Si, Nb, Ti, and Mg elements can precipitate together with Cr atoms during the aging process and agglomerate inside or on the surface of the Cr-rich precipitate phase, forming a more stable coherent precipitate phase. This hinders the further growth of the precipitate phase under high temperature, thereby refining the precipitate phase size and enhancing the precipitation strengthening effect of the alloy. It can improve the overall strength and heat resistance of the alloy material at room temperature and high temperature while ensuring the high conductivity of the Cu-Cr-Zr alloy.

[0056] In the high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material of this invention, trace amounts of added Si and Nb elements can combine with Cr during solidification to form hard phases with high thermal stability, such as Cr3Si and Cr2Nb. These hard particles are broken down and refined during processing and deformation, becoming the nuclei for recrystallization and further refining the grains. Furthermore, these fine hard phase particles are distributed around the grain boundaries, which helps to pin the grain boundaries, reduce grain boundary mobility, and thus improve grain boundary stability. This is beneficial for improving the alloy material's resistance to deformation and tensile properties at both room temperature and high temperatures.

[0057] In the high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material of this invention, the trace addition of Ag and Zn elements has minimal impact on the electrical conductivity of the copper alloy and will not significantly reduce the alloy's conductivity. Ag and Zn are uniformly dissolved in the copper matrix, achieving solid solution strengthening without significantly reducing conductivity, and their existence is not easily affected by the aging process. This reduces the stacking fault energy of the alloy, hinders the interaction between dislocations, retains a higher dislocation density and more substructures in the alloy matrix, and improves the alloy's recrystallization temperature and resistance to softening.

[0058] The method for preparing high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy materials of the present invention adopts a non-vacuum melting method, which avoids the disadvantages of vacuum melting, such as high equipment requirements, low efficiency, high cost, and unfavorable conditions for large-scale production. Furthermore, it proposes to use an intermediate alloy as a raw material to add elements with higher melting points, thereby further shortening the melting time and reducing the melting temperature, thus significantly reducing the burn-off of non-vacuum melting.

[0059] The method for preparing high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy materials of the present invention prepares electrode materials for resistance spot welding through a process of homogenization-hot working-solution-cold working-aging. Compared with powder metallurgy methods, it has better production continuity, which is conducive to the preparation of high-performance products through large-scale production. It has the characteristics of high production efficiency and low production cost.

[0060] The high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material of the present invention has a room temperature hardness ≥190HV, a room temperature tensile strength ≥650MPa, a room temperature elongation ≥15%, a room temperature conductivity ≥80%IACS, a softening temperature ≥600℃, and a tensile strength ≥350MPa at 500℃. Attached Figure Description

[0061] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0062] Figure 1 The images show actual photos of high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy bars of different sizes after secondary aging, prepared in Example 1 of this invention.

[0063] Figure 2 The metallographic structure after solution treatment during the alloy preparation process in Example 1 of this invention.

[0064] Figure 3 The metallographic structure after secondary cold forging during the alloy preparation process in Example 1 of this invention.

[0065] Figure 4 The image shows the SEM observation results after secondary aging during the alloy preparation process in Example 1 of this invention.

[0066] Figure 5 The results are TEM observations after secondary aging during the alloy preparation process in Example 1 of this invention.

[0067] Figure 6 The results are TEM observations after secondary aging during the alloy preparation process in Example 1 of this invention.

[0068] Figure 7 The results are TEM observations after testing the alloy softening temperature in Example 1 of this invention. Detailed Implementation

[0069] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0070] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0071] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0072] Example 1

[0073] Example 1 prepared a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material. By mass percentage, the material composition included Cr: 1.1%, Zr: 0.1%, Fe: 0.05%, Si: 0.05%, Mg: 0.05%, Zn: 0.2%, Sn: 0.01%, Nb: 0.01%, Ag: 0.01%, Ti: 0.01%, with the balance being Cu.

[0074] Example 1 describes the preparation method of the high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material. The preparation process includes:

[0075] Step (1): Non-vacuum melting is carried out in a medium-frequency induction melting furnace to obtain ingots. The raw materials added for melting include electrolytic copper (99.95wt.%), Cu-10wt.%Cr master alloy, Cu-40wt.%Zr master alloy, Cu-5wt.%Nb master alloy, Cu-60wt.%Ti master alloy, pure Fe (99.95wt.%), pure Si (99.95wt.%), pure Mg (99.95wt.%), pure Zn (99.95wt.%), pure Sn (99.95wt.%), and pure Ag (99.95wt.%). Before melting, the raw materials, crucible, and mold are dried. The smelting process begins by melting pure copper (1083℃). When the melt temperature reaches 1250℃, pure Fe, pure Ag, pure Zn, and pure Sn are added. Once the temperature rises to 1350℃, a Cu-Cr master alloy is added in four batches. After holding the mixture at this temperature for 2.5 minutes, mechanical stirring is performed for 30 seconds at a stirring speed of 80 r / min. Subsequently, Cu-Nb master alloy, Cu-Ti master alloy, pure Si, pure Mg, and Cu-Zr master alloy are added. After holding the mixture at this temperature for another 1.5 minutes, mechanical stirring is performed while the induction furnace power is reduced (this process lasts for 60 seconds) to lower the melt temperature to 1200℃ before casting begins.

[0076] Step (2) Homogenize the ingot at a temperature of 960℃ for 3 hours and water quenching. Then, machine the ingot to remove and correct surface defects to ensure that the ingot surface is free of oxide layer, shrinkage cavities and internal holes.

[0077] Step (3) Hot processing is carried out on the homogenized billet. Hot extrusion is used with a hot extrusion ratio of 5:1. The billet is kept at a temperature of 960℃ for 1 hour before hot extrusion. The extrusion die is kept at a temperature of 500℃ for 500 hours. The average pressure of the press during extrusion is 600MPa and the maximum pressure is 700MPa. After hot extrusion, the billet is water quenched.

[0078] Step (4) The billet is subjected to solution treatment at a temperature of 960℃ for 2 hours and water quenching.

[0079] Step (5) pre-aging of the solution-treated bar at a temperature of 450°C for 45 minutes and water quenching.

[0080] Step (6) The bar after pre-aging treatment is cold-worked. The cold working method is cold rotary forging. The final state of rotary forging is achieved through multiple passes. The total rotary forging deformation is 80%. The bar after cold working is aged at a temperature of 450℃ for 120 minutes and cooled by water quenching.

[0081] Step (7) is to perform secondary cold working, the processing method is cold rotary forging, the final state of rotary forging is achieved through multiple passes, the total rotary forging deformation is 50%, the bar after secondary cold working is subjected to aging treatment, the aging temperature is 400℃, the aging time is 60min, and the cooling method is water quenching.

[0082] Step (8) involves machining the bar stock after secondary aging to obtain the finished product.

[0083] Figure 1 The images show actual photos of high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy bars of different sizes after secondary aging, prepared in Example 1 of this invention.

[0084] Figure 2 The image shows the metallographic structure after solution treatment during the alloy preparation process in Example 1 of this invention. It can be seen that the matrix after solution treatment contains distinct equiaxed grains with a grain size of approximately 100–200 μm. This effectively improves the uneven grain size distribution after hot working, forming a saturated solid solution, which prepares the alloy for solution strengthening and subsequent aging precipitation.

[0085] Figure 3 The metallographic structure after secondary cold forging during the alloy preparation process in Example 1 of this invention is shown. It can be seen that the matrix contains elongated fibrous structures with lengths along the rotation axis. This fibrous structure can effectively improve the axial tensile strength and electrical conductivity of the material.

[0086] Figure 4This is a scanning electron microscope (SEM) image of the alloy after secondary aging during the preparation process of Example 1 of the present invention. It can be seen that micron- and submicron-sized Cr-rich primary phases are uniformly distributed in the alloy matrix. On the one hand, this enhances the arc-extinguishing performance of the resistance spot welding electrode; on the other hand, it acts as a pinning agent for grain boundary movement at high temperatures, thereby improving the high-temperature performance of the alloy material.

[0087] Figure 5 The TEM observation results are shown in Example 1 of this invention after secondary aging during alloy preparation. It can be seen that a large number of entangled dislocation lines exist in the alloy matrix after aging. Through the interaction between nanoscale precipitates and high-density dislocations, the strength and conductivity of the alloy are improved.

[0088] Figure 6 The TEM observation results of the precipitates after secondary aging during the alloy preparation process in Example 1 of this invention are shown. It can be seen that fine and dispersed nanoscale Cr-rich precipitates are distributed in the alloy matrix, which can effectively pin dislocation migration, refine grains, and greatly improve the strength and toughness of the material.

[0089] The physical properties of the high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material prepared in Example 1 were tested, and the test results are shown in Table 1.

[0090] Table 1

[0091]

[0092]

[0093] Figure 7 The results are TEM observations after testing the softening temperature of the alloy in Example 1 of this invention. Uniformly distributed recrystallized equiaxed grains with a size of 250 nm-550 nm were observed. Submicron-sized Cr3Si particles were also observed at grain boundaries and grain boundary corners, which pinned the grain boundaries and hindered the rapid migration of grain boundaries and subgrain boundaries at high temperatures, thus improving the material's high-temperature softening resistance and high-temperature strength.

[0094] Example 2

[0095] Example 2 prepared a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material. By mass percentage, the material composition included Cr: 1.8%, Zr: 0.05%, Fe: 0.03%, Si: 0.01%, Mg: 0.01%, Zn: 0.1%, Sn: 0.01%, Nb: 0.1%, Ag: 0.01%, Ti: 0.01%, with the balance being Cu.

[0096] Example 2 describes the preparation method of the high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material. The preparation process includes:

[0097] Step (1): Non-vacuum melting is carried out in a medium-frequency induction melting furnace to obtain ingots. The raw materials added during melting include electrolytic copper (99.95 wt.%), Cu-15 wt.% Cr master alloy, Cu-35 wt.% Zr master alloy, Cu-4 wt.% Nb master alloy, Cu-50 wt.% Ti master alloy, pure Si (99.95 wt.%), pure Mg (99.95 wt.%), pure Zn (99.95 wt.%), pure Sn (99.95 wt.%), and pure Ag (99.95 wt.%). Before smelting, the raw materials, crucible, and mold are dried. During the smelting process, pure copper is first melted (1083℃). When the melt temperature is 1260℃, pure Fe, pure Ag, pure Zn, and pure Sn are added. When the temperature rises to 1400℃, Cu-Cr master alloy is added in three batches. After holding for 2 minutes, mechanical stirring is performed for 45 seconds at a stirring speed of 60 r / min. Then, Cu-Nb master alloy, Cu-Ti master alloy, pure Si, pure Mg, and Cu-Zr master alloy are added. After holding for another 2 minutes, mechanical stirring is performed while the power of the induction furnace is reduced (the process lasts for 45 seconds) to lower the melt temperature to 1215℃, at which point casting can begin.

[0098] Step (2) Homogenize the ingot at a temperature of 940℃ for 2 hours and water quenching. Then, machine the ingot surface defects to ensure that there are no oxide layers, shrinkage cavities, or internal holes on the ingot surface.

[0099] Step (3) Hot processing is performed on the homogenized billet. Hot forging is used, and the final state of forging is achieved through multiple passes. The total deformation is 70%. The billet is kept at 940℃ before hot forging for 1 hour. The average pressure of the press during forging is 600MPa and the maximum pressure is 700MPa. After hot forging, the billet is water quenched.

[0100] Step (4) The billet is subjected to solution treatment at a temperature of 940℃ for 1.5 hours and cooled by water quenching.

[0101] Step (5) Pre-aging of the solution-treated bar at 430℃ for 60 min, using water quenching as the cooling method. Step (6) Cold working of the solution-treated bar using cold rolling, achieving the final state through multiple passes with a total rolling deformation of 70%. Aging treatment of the bar after cold working at 400℃ for 180 min, using water quenching as the cooling method.

[0102] Step (7) is to perform secondary cold working, the processing method is cold hole rolling, the final state of hole rolling is achieved through multiple passes, the total rolling deformation is 60%, the bar after secondary cold working is subjected to aging treatment, the aging temperature is 400℃, the aging time is 100min, and the cooling method is water quenching.

[0103] Step (8) involves machining the bar stock after secondary aging to obtain the finished product.

[0104] The physical properties of the high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material prepared in Example 2 were tested, and the test results are shown in Table 2.

[0105] Table 2

[0106] project Test Results Test methods room temperature hardness 180HV YS / T 471-2004 room temperature tensile strength 662MPa GB / T 34505-2017 room temperature elongation 15.6％ GB / T 34505-2017 Room temperature conductivity 83.1% IACS GB / T 32791-2016 softening temperature 607℃ GB / T 33370-2016 Tensile strength at 500℃ 352MPa GB / T 228.2-2015

[0107] Comparative Example 1

[0108] The composition of the Cu-Cr-Zr alloy material prepared in Comparative Example 1 was the same as that in Example 1.

[0109] The preparation method of the Cu-Cr-Zr alloy material selected in Comparative Example 1 includes:

[0110] Step (1): Non-vacuum melting is carried out in a medium-frequency induction melting furnace to obtain ingots. The raw materials added during melting include electrolytic copper (99.95 wt.%), Cu-16 wt.% Cr master alloy, Cu-38 wt.% Zr master alloy, Cu-4 wt.% Nb master alloy, Cu-51 wt.% Ti master alloy, pure Fe (99.95 wt.%), pure Si (99.95 wt.%), pure Mg (99.95 wt.%), pure Zn (99.95 wt.%), pure Sn (99.95 wt.%), and pure Ag (99.95 wt.%). Before smelting, the raw materials, crucible, and mold are dried. In the smelting process, pure copper is first melted (1083℃). When the melt temperature is 1260℃, pure Fe, pure Ag, pure Zn, and pure Sn are added. When the temperature rises to 1400℃, Cu-Cr master alloy is added in three batches. Then, Cu-Nb master alloy, Cu-Ti master alloy, pure Si, pure Mg, and Cu-Zr master alloy are added. After holding at this temperature for 2 minutes, the power of the induction furnace is reduced (the process lasts for 45 seconds) so that the melt temperature drops to 1215℃, at which point casting can begin. During this smelting process, the mechanical stirring process is carried out continuously, and the stirring rotor speed is 125 r / min.

[0111] In the preparation method of Comparative Example 1, except for the raw material preparation and non-vacuum melting process, the remaining deformation heat treatment process is the same as that of Example 1.

[0112] The physical properties of the Cu-Cr-Zr alloy material prepared in Comparative Example 1 were tested, and the test results are shown in Table 3.

[0113] Table 3

[0114] project Test Results Test methods room temperature hardness 177HV YS / T 471-2004 room temperature tensile strength 592MPa GB / T 34505-2017 room temperature elongation 12.3％ GB / T 34505-2017 Room temperature conductivity 80.1% IACS GB / T 32791-2016 softening temperature 534℃ GB / T 33370-2016 Tensile strength at 500℃ 204MPa GB / T 228.2-2015

[0115] A comparison of the test results of Example 1 and Comparative Example 1 shows that the softening temperature and high-temperature tensile strength of Comparative Example 1 are significantly lower. Composition analysis of the material obtained in Comparative Example 1 revealed that the Cr content was 0.36 wt.%, while the contents of several easily burnable alloying elements (Zr, Mg, etc.) were all below 0.01 wt.%. It can be seen that continuous stirring increases the burn-off rate and oxygen content, which is also detrimental to the dissolution of Cr. This indicates that only by controlling the timing of stirring can the alloy composition designed in this patent be obtained.

[0116] Comparative Example 2

[0117] The composition of the Cu-Cr-Zr alloy material prepared in Comparative Example 2 was the same as that in Example 1.

[0118] The preparation method of the Cu-Cr-Zr alloy material selected in Comparative Example 2 includes:

[0119] Step (1): Non-vacuum melting is carried out in a medium-frequency induction melting furnace to obtain ingots. The raw materials added during melting include electrolytic copper (99.95 wt.%), Cu-60 wt.% Cr master alloy, Cu-38 wt.% Zr master alloy, Cu-4 wt.% Nb master alloy, Cu-51 wt.% Ti master alloy, pure Fe (99.95 wt.%), pure Si (99.95 wt.%), pure Mg (99.95 wt.%), pure Zn (99.95 wt.%), pure Sn (99.95 wt.%), and pure Ag (99.95 wt.%). Before smelting, the raw materials, crucible, and mold are dried. During the smelting process, pure copper is first melted (1083℃). When the melt temperature reaches 1271℃, pure Ag, pure Zn, and pure Sn are added. Once the temperature rises to 1388℃, a Cu-Cr master alloy is added in three batches. After holding at this temperature for 3 minutes, mechanical stirring is performed for 47 seconds at a stirring speed of 60 r / min. Subsequently, Cu-Nb, Cu-Ti, pure Si, pure Mg, and Cu-Zr master alloys are added. After holding at this temperature for another 2 minutes, mechanical stirring is performed while simultaneously reducing the induction furnace power (this process lasts 43 seconds), lowering the melt temperature to 1211℃, at which point casting can begin.

[0120] In the preparation method of Comparative Example 2, except for the raw material preparation and non-vacuum melting process, the remaining deformation heat treatment process is the same as that of Example 1.

[0121] The physical properties of the Cu-Cr-Zr alloy material prepared in Comparative Example 2 were tested, and the test results are shown in Table 4.

[0122] Table 4

[0123] project Test Results Test methods room temperature hardness 154HV YS / T 471-2004 room temperature tensile strength 478MPa GB / T 34505-2017 Room temperature elongation 19.2％ GB / T 34505-2017 Room temperature conductivity 88.2% IACS GB / T 32791-2016 softening temperature 509℃ GB / T 33370-2016 Tensile strength at 500℃ 195MPa GB / T 228.2-2015

[0124] A comparison of the test results of Example 1 and Comparative Example 2 shows that the overall strength and high-temperature resistance of Comparative Example 2 are significantly reduced. Composition analysis of the material obtained in Comparative Example 2 revealed that the Cr content was less than 0.05 wt.%. This analysis indicates that the Cu-60 wt.% Cr master alloy used in Comparative Example 2 is not suitable for the non-vacuum melting process restricted by this patent. Only by using a Cu-Cr master alloy with an appropriate mass fraction can burn-off be effectively reduced.

[0125] Comparative Example 3

[0126] Comparative Example 3 prepared a Cu-Cr-Zr alloy material. By mass percentage, the material composition included Cr: 1.5%, Zr: 0.1%, Fe: 1.0%, Si: 0.5%, Mg: 0.01%, Zn: 0.1%, Sn: 0.5%, Nb: 0.01%, Ag: 0.5%, Ti: 0.01%, with the balance being Cu.

[0127] The preparation method of the high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material selected in Comparative Example 3 is the same as that in Example 1.

[0128] The physical properties of the Cu-Cr-Zr alloy material prepared in Comparative Example 3 were tested, and the test results are shown in Table 5.

[0129] Table 5

[0130] project Test Results Test methods room temperature hardness 181HV YS / T 471-2004 room temperature tensile strength 572MPa GB / T 34505-2017 room temperature elongation 9.3％ GB / T 34505-2017 Room temperature conductivity 61.1% IACS GB / T 32791-2016 softening temperature 606℃ GB / T 33370-2016 Tensile strength at 500℃ 346MPa GB / T 228.2-2015

[0131] A comparison of the test results of Example 1 and Comparative Example 3 shows that increasing the amount of Fe, Si, Sn, and Ag elements, which should have been added in trace amounts to the material composition, resulted in a significant decrease in the room temperature elongation and room temperature conductivity of Comparative Example 1. This may be because the excessive addition of these elements leads to more alloying elements dissolving in the Cu matrix and failing to fully precipitate during the aging process, thus reducing the degree of conductivity improvement during aging. Furthermore, the excessive addition of Ag increases the brittleness of the material, resulting in a decrease in elongation at fracture.

[0132] Comparative Example 4

[0133] The composition of the Cu-Cr-Zr alloy material prepared in Comparative Example 4 was the same as that in Example 1.

[0134] The preparation method of the Cu-Cr-Zr alloy material selected in Comparative Example 4 includes:

[0135] Step (1): Ingots are obtained by non-vacuum melting in a medium-frequency induction melting furnace. The raw materials and non-vacuum melting process are the same as in Example 1.

[0136] Step (2) Homogenize the ingot at a temperature of 800℃ for 3 hours and water quenching. Then, machine the ingot surface to remove and correct defects, ensuring that the ingot surface is free of oxide layer, shrinkage cavities and internal holes.

[0137] Step (3) Hot processing is carried out on the homogenized billet. Hot extrusion is used with a hot extrusion ratio of 5:1. The billet is kept at a temperature of 960℃ for 1 hour before hot extrusion. The extrusion die is kept at a temperature of 500℃ for 500 hours. The average pressure of the press during extrusion is 600MPa and the maximum pressure is 700MPa. After hot extrusion, the billet is water quenched.

[0138] Step (4) The billet is subjected to solution treatment at a temperature of 800℃ for 2 hours and cooled by water quenching.

[0139] Step (5) The bar after solution treatment is subjected to a cold working. The cold working method is cold rotary forging. The final state of rotary forging is achieved through multiple passes. The total rotary forging deformation is 80%. The bar after the first cold working is subjected to aging treatment. The aging temperature is 450℃ and the aging time is 120min. The cooling method is water quenching.

[0140] Step (6) is to perform secondary cold working. The cold working method is cold rotary forging. The final state of rotary forging is achieved through multiple passes. The total rotary forging deformation is 80%. The bar after the first cold working is subjected to aging treatment. The aging temperature is 400℃ and the aging time is 100min. The cooling method is water quenching.

[0141] Step (7) involves machining the bar stock after secondary aging to obtain the finished product.

[0142] The physical properties of the Cu-Cr-Zr alloy material prepared in Comparative Example 4 were tested, and the test results are shown in Table 6.

[0143] Table 6

[0144] project Test Results Test methods room temperature hardness 160HV YS / T 471-2004 room temperature tensile strength 433MPa GB / T 34505-2017 Room temperature elongation 15.5％ GB / T 34505-2017 Room temperature conductivity 84.9% IACS GB / T 32791-2016 softening temperature 539℃ GB / T 33370-2016 Tensile strength at 500℃ 248MPa GB / T 228.2-2015

[0145] A comparison of the test results from Example 1 and Comparative Example 4 shows that the decrease in heat treatment temperature during material preparation leads to a significant reduction in the material's room temperature hardness, tensile strength, and high-temperature performance. This may be because, on the one hand, the excessively low homogenization temperature prevents the effective elimination of dendrites in the material matrix during homogenization, resulting in poor compositional homogenization; on the other hand, the excessively low solution temperature primarily prevents Cr from fully dissolving in the Cu matrix, thus hindering the formation of a supersaturated solid solution after quenching. Consequently, a large amount of fine, dispersed strengthening phases cannot be generated in the matrix during aging. These factors combined result in a decrease in the overall strength and hardness of the material.

[0146] Comparative Example 5

[0147] The composition of the Cu-Cr-Zr alloy material prepared in Comparative Example 5 was the same as that in Example 2.

[0148] The preparation method of the Cu-Cr-Zr alloy material selected in Comparative Example 5 includes:

[0149] Step (1): Ingots are obtained by non-vacuum melting in a medium-frequency induction furnace. The raw materials and non-vacuum melting process are the same as in Example 2.

[0150] Step (2) Homogenize the ingot at a temperature of 940℃ for 2 hours and water quenching. Then, machine the ingot surface defects to ensure that there are no oxide layers, shrinkage cavities, or internal holes on the ingot surface.

[0151] Step (3) Hot processing is performed on the homogenized billet. Hot forging is used, and the final state of forging is achieved through multiple passes. The total deformation is 30%. The billet is kept at 940℃ before hot forging for 1 hour. The average pressure of the press during forging is 600MPa and the maximum pressure is 700MPa. After hot forging, the billet is quenched in water.

[0152] Step (4) The billet is subjected to solution treatment at a temperature of 940℃ for 1.5 hours and cooled by water quenching.

[0153] Step (5) The bar after solution treatment is subjected to a cold working process. The cold working method is cold hole rolling. The final state of the hole rolling is achieved through multiple passes. The total rolling deformation is 30%. The bar after the first cold working is subjected to aging treatment. The aging temperature is 400℃ and the aging time is 180min. The cooling method is water quenching.

[0154] Step (6) involves secondary cold working, which is cold hole rolling. The final state of the hole rolling is achieved through multiple passes, with a total rolling deformation of 20%. The bar after secondary cold working is then subjected to aging treatment at a temperature of 350°C for 120 minutes, and water quenching is used for cooling.

[0155] After aging in step (7), the bar stock is machined to obtain the finished product.

[0156] The physical properties of the Cu-Cr-Zr alloy material prepared in Comparative Example 5 were tested, and the test results are shown in Table 7.

[0157] Table 7

[0158] project Test Results Test methods room temperature hardness 155HV YS / T 471-2004 room temperature tensile strength 425MPa GB / T 34505-2017 room temperature elongation 19.6％ GB / T 34505-2017 Room temperature conductivity 85.1% IACS GB / T 32791-2016 softening temperature 550℃ GB / T 33370-2016 Tensile strength at 500℃ 198MPa GB / T 228.2-2015

[0159] A comparison of the test results of Example 2 and Comparative Example 5 shows that the reduction in processing deformation during material preparation leads to a significant decrease in the material's room temperature hardness, tensile strength, and high-temperature performance. Hot and cold working processes can introduce a large number of dislocations and substructures into the material matrix, thereby achieving work hardening and enabling the formation of finer grains during recrystallization, resulting in grain refinement strengthening. Comparative Example 5, due to its lower processing amount, exhibits a weaker strengthening effect and naturally cannot achieve the same effect as Example 2.

[0160] Comparative Example 6

[0161] The composition of the Cu-Cr-Zr alloy material prepared in Comparative Example 6 was the same as that in Example 2.

[0162] In the preparation method of the high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material selected in Comparative Example 6, pre-aging was not performed, and other processes were the same as in Example 2.

[0163] The physical properties of the Cu-Cr-Zr alloy material prepared in Comparative Example 6 were tested, and the test results are shown in Table 8.

[0164] Table 8

[0165] project Test Results Test methods room temperature hardness 176HV YS / T 471-2004 room temperature tensile strength 619MPa GB / T 34505-2017 room temperature elongation 15.9％ GB / T 34505-2017 Room temperature conductivity 81.3% IACS GB / T 32791-2016 softening temperature 603℃ GB / T 33370-2016 Tensile strength at 500℃ 329MPa GB / T 228.2-2015

[0166] A comparison of the test results from Example 2 and Comparative Example 6 shows that pre-aging treatment can improve the overall strength of Cu-Cr-Zr alloy materials to a certain extent. This is because aging treatment before deformation allows for more complete precipitation of the Cr-rich phase, resulting in a more significant precipitation strengthening effect. After solution treatment, the material has a certain precipitation motive force, allowing for the pre-aging process to induce the early precipitation of some Cr elements. Each deformation also provides precipitation motive force for subsequent aging treatments, and three aging processes result in a better precipitation effect than two aging processes.

[0167] As can be seen from Examples 1, 2, 1, 2, 3, 4, 5, and 6, the Cu-Cr-Zr alloy material prepared by the present invention has the characteristics of high hardness, high strength, high conductivity, high softening temperature, and excellent high-temperature performance. There is a synergistic effect between the various processes and conditions in the present invention. When a certain parameter or process step is not within the protection scope of the present invention, the performance of the product obtained is far inferior to that of the present invention.

[0168] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material, characterized in that: According to the design ratio, each metal raw material is mixed and non-vacuum smelted to obtain ingots. The ingots are homogenized to obtain billets. The billets are hot-worked to obtain bars. The bars are sequentially subjected to solution treatment, pre-aging treatment, first cold working, first aging, second cold working, and second aging to obtain Cu-Cr-Zr alloy materials. The specific steps for preparing each metal raw material according to the design ratio are as follows: Prepare pure copper, Cu-Cr master alloy, Cu-Zr master alloy, Cu-Nb master alloy, Cu-Ti master alloy, pure Fe, pure Si, pure Mg, pure Sn, pure Ag, and pure Zn according to the design ratio. In the Cu-Cr master alloy, the mass fraction of Cr is ≤20%. First, pure copper is melted, then heated to 1200~1300℃, and pure Fe, pure Ag, pure Zn, and pure Sn are added. The temperature is then raised to 1300~1400℃, and Cu-Cr master alloy is added in 3~4 batches. After holding at this temperature for 2~3 minutes, the mixture is stirred for 30~60 seconds. Then, Cu-Nb master alloy, Cu-Ti master alloy, pure Si, pure Mg, and Cu-Zr master alloy are added. After holding at this temperature for 1~2 minutes, the temperature is lowered to 1100℃~1200℃ while stirring, and then the mixture is cast to obtain an ingot. All stirring is done using mechanical uniform stirring at a speed of 60~100 r / min. The homogenization treatment temperature is 900~1000℃, the homogenization treatment time is 2-4h, and the billet is obtained by water quenching after the homogenization treatment is completed. The deformation during hot working is 50%~80%. The solution treatment temperature is 940~1000℃. The pre-aging temperature is 400-500℃, and the pre-aging time is 30-120 min; The first cold working is cold rotary forging, and the deformation amount of the first cold working is 50%~80%; The temperature of the first aging is 400℃~500℃, the time of the first aging is 30min~300min, and the water quenching is performed after the first aging. The secondary cold working is cold rotary forging, and the deformation amount of the secondary cold working is 50%~80%; The temperature of the secondary aging is 400℃~500℃, the time of the secondary aging is 30min~300min, and the second aging is followed by water quenching. The Cu-Cr-Zr alloy material, by mass percentage, has the following composition: Cr: 1.1~1.8%, Zr: 0.05~0.1%, Fe: 0.03~0.05%, Si: 0.01~0.05%, Mg: 0.01~0.05%, Zn: 0.1~0.2%, Sn: 0.01%, Nb: 0.01~0.1%, Ag: 0.01% of the total mass of Si, Mg, Zn, Sn, Nb, Ag, and Ti is less than 0.5%.

2. The method for preparing a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material according to claim 1, characterized in that: The Cu-Zr master alloy has a Zr mass fraction ≤50%. The Cu-Nb master alloy has an Nb mass fraction ≤ 5%. The Cu-Ti master alloy has a Ti mass fraction ≤60%. The pure copper is electrolytic copper, and the purity of the pure copper is ≥99.95 wt.%, the purity of pure Fe is ≥99.95 wt.%, the purity of pure Si is ≥99.95 wt.%, the purity of pure Mg is ≥99.95 wt.%, the purity of pure Sn is ≥99.95 wt.%, and the purity of pure Ag is ≥99.95 wt.%.

3. The method for preparing a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material according to claim 1, characterized in that: The stirring head used for stirring is made of graphite. During the non-vacuum melting process, the melt is covered with graphite; The ingot is obtained by pouring it into a mold that has been preheated to 400℃~500℃; The time from adding the Cu-Cr master alloy during the non-vacuum melting process to casting is ≤10 minutes.

4. The preparation method of a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material according to claim 1, characterized in that: The hot working is selected from hot extrusion or hot forging. The holding temperature before hot working is 900~1000℃ and the holding time is 1~2h. After hot working, the water is quenched. The solution treatment time is 2-4 hours, followed by water quenching after the solution treatment is completed.

5. The application of a high-strength, high-conductivity, and heat-resistant Cu-Cr-Zr alloy material prepared by the preparation method according to any one of claims 1-4, characterized in that: Cu-Cr-Zr alloy materials are used to prepare resistance spot welding electrodes.

Images