High-strength wear-resistant lead-free copper alloy and preparation method and application thereof

Abstract

The invention provides a high-strength wear-resistant lead-free copper alloy and a preparation method and application thereof. The high-strength wear-resistant lead-free copper alloy comprises the following components in percentage by mass: 5 to 15 percent of Al, 2 to 5 percent of Fe, 1 to 3 percent of Ni, 1 to 3 percent of Cr, 0.1 to 0.5 percent of Mn, 0.05 to 0.2 percent of Sn, 0.1 to 0.2 percent of Si, 0.05 to 0.2 percent of Mo and the balance of Cu. According to the high-strength wear-resistant copper alloy, multiple alloy elements are added, a proper heat treatment process is combined, multiple high-hardness phases formed by the alloy elements are synergistically strengthened, and the wear resistance and stability of the alloy are improved. The comprehensive performance of the alloy is that the hardness is larger than or equal to 350 HV, the tensile strength is larger than or equal to 850 MPa, and the ductility is larger than or equal to 1.5%. Under the test conditions of the invention, the friction coefficient is less than or equal to 0.15. The invention further provides a preparation method and application of the high-strength wear-resistant lead-free copper alloy.

Description

Technical Field

[0001] This invention belongs to the field of copper alloy technology, specifically relating to a high-strength, wear-resistant, lead-free copper alloy, its preparation method, and its application. Background Technology

[0002] With the rapid development of the automotive, construction machinery, and nuclear power equipment industries towards higher reliability, longer lifespan, and environmental friendliness, high-strength wear-resistant copper alloys, as core materials for critical transmission and friction components, face increasingly stringent performance requirements. These components include automotive valve guides, floating bearings, worm gears in nuclear power equipment, guide sleeves in high-speed punch presses, and transmission gears in rotary kilns. They not only need excellent mechanical properties to withstand heavy loads and impacts but also high wear resistance to resist long-term frictional losses. Especially under harsh conditions such as high temperatures, high radiation, and corrosive gases, materials must possess even stronger environmental adaptability to meet the demands of equipment upgrades.

[0003] In existing technologies, widely used high-strength, wear-resistant brass (such as grade CuZn37Mn3Al2PbSi) achieves high strength and hardness through solid solution strengthening with aluminum, enhances wear resistance by forming wear-resistant phases with silicon and manganese, and optimizes machinability by adding a small amount of lead. However, with increasingly stringent global environmental regulations, some countries and regions have explicitly restricted the use of harmful elements such as lead. Lead-containing copper alloys easily cause environmental pollution during production and service, and can also harm human health, making them unsuitable for the market demand for lead-free production. Therefore, lead-free improvements have become an inevitable trend in the industry.

[0004] In response to lead-free requirements, some improved solutions have emerged in existing technologies. CN107723505A designs a wear-resistant copper alloy mainly containing elements such as Mn, Al, Si, Sn, Ni, Co, Fe, and Mg. Although it avoids the use of lead and has excellent mechanical properties, the large number of alloying elements increases the difficulty of preparation, and the high prices of elements such as Sn, Ni, and Co increase the cost of the alloy. CN104164589B prepares a lead-free high-strength wear-resistant copper alloy by adding Ni, Sn, and lanthanum-cerium composite rare earth elements, but it also suffers from high costs. In summary, the core technical challenge currently facing the industry is that existing high-strength wear-resistant copper alloys either do not comply with environmental regulations due to lead content, or although they achieve lead-free status, they suffer from high costs and difficult processing, failing to simultaneously meet the comprehensive performance requirements of high strength, high wear resistance, lead-free environmental protection, and low cost. Therefore, developing a low-cost, high-strength, wear-resistant, lead-free copper alloy to fill the existing technological gap and adapt to the upgrading needs of the automotive, construction machinery, and nuclear power industries has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a high-strength, wear-resistant, lead-free copper alloy that simultaneously meets the comprehensive performance requirements of high strength, high wear resistance, lead-free environmental friendliness, and low cost.

[0006] The present invention also provides a method for preparing a high-strength, wear-resistant, lead-free copper alloy.

[0007] This invention also provides the application of high-strength, wear-resistant, lead-free copper alloys in the manufacture of transmission or friction components.

[0008] The first aspect of the present invention provides a high-strength, wear-resistant, lead-free copper alloy, comprising, by weight percentage: Al: 5-15%, Fe: 2-5%, Ni: 1-3%, Cr: 1-3%, Mn: 0.1-0.5%, Sn: 0.05-0.2%, Si: 0.1-0.2%, Mo: 0.05-0.2%, The balance is Cu.

[0009] The high-strength, wear-resistant, lead-free copper alloy of the present invention has at least the following beneficial effects: Lead-free and environmentally friendly, meeting environmental requirements. The copper alloy component of this invention does not contain lead, eliminating the soil and water pollution problems caused by lead leaching during the production, processing, and service of traditional lead-containing copper alloys (such as CuZn37Mn3Al2PbSi). At the same time, it avoids the health hazards of lead to production personnel and end users, fully complying with increasingly stringent environmental protection standards worldwide. It is suitable for fields with extremely high environmental requirements, such as automobiles, nuclear power, and construction machinery, meeting the core needs of the lead-free market.

[0010] Through multi-element synergistic reinforcement, a combination of high strength and high wear resistance is achieved.

[0011] Synergistic enhancement of hardness and strength through strengthening phases: 5-15% Al in the composition can form α phase (copper-based solid solution), β' phase (Cu3Al, stable at 325℃ with high strength and hardness), and γ2 phase (Cu9Al4, microhardness 500-600HV) in the matrix, providing basic strengthening for the alloy; 2-5% Fe can form body-centered cubic FeAl and FeAl3 phases (collectively referred to as κ phase), which not only improves hardness and wear resistance but also refines grains; 1-3% Ni can form NiAl phase with Al, further refining grains and inhibiting the formation of coarse γ2 phase to eliminate alloy brittleness; 1-3% Cr forms fine Cr particles or intermetallic compounds with Fe and Al during the smelting stage; 0.1-0.2% Si can form high-hardness Mn5Si3 wear-resistant phase (high melting point, stable at high temperature) with Mn; 0.05-0.2% Mo can inhibit the coarsening of various wear-resistant phases during heat treatment. The synergistic effect of multiple strengthening phases can make the alloy hardness ≥350HV and tensile strength ≥850MPa, which can meet the high strength requirements of key transmission and friction components such as automotive valve guides and nuclear power equipment worm gears, and withstand heavy loads and impact loads.

[0012] Low coefficient of friction ensures high wear resistance: Al element promotes the spontaneous formation of Al2O3-Cu2O composite oxide film on the alloy surface. Al2O3 has extremely high hardness, strong chemical stability and dense structure, which can isolate the metal at the friction interface from direct contact and avoid adhesive wear. Cu2O has a certain degree of lubrication, which can reduce the coefficient of friction. At the same time, the high-hardness phase formed by Fe, Cr and Si can resist long-term frictional wear. Combined with the inhibitory effect of Mo on the coarsening of the wear-resistant phase, the coefficient of friction of the alloy is ≤0.15, which significantly improves the wear resistance, extends the service life of the components and meets the long-term use requirements under harsh conditions such as high temperature and high radiation.

[0013] The composition ratio is scientific, taking into account both performance stability and processing feasibility.

[0014] The limitations on the content of each element in this invention (e.g., Al≤15%, Fe≤5%) can effectively avoid performance shortcomings. Controlling the Al content can prevent excessive coarsening of the γ2 phase, which can lead to brittleness of the alloy. The Fe content ≤5% can prevent the alloy's corrosion resistance from deteriorating. At the same time, Sn (0.05-0.2%) can suppress the high-temperature oxidation tendency of the alloy melt and can also be dissolved into the matrix to enhance the solid solution strengthening effect, improve corrosion resistance and hardness, and further optimize the overall performance of the alloy.

[0015] Adaptable to subsequent processing techniques: The composition design is highly compatible with preparation processes such as hot extrusion and solution aging. Hot extrusion can eliminate casting defects and break up coarse grains, while solution aging can ensure the uniform precipitation of each strengthening phase. The content range of each element in the composition (such as Mn 0.1-0.5%, Si 0.1-0.2%) can ensure that during the heat treatment process, the strengthening phase can be fully precipitated to improve performance, without causing processing cracks due to excessive or coarse phases, thus ensuring the quality of alloy processing and meeting the process requirements for subsequent manufacturing of transmission and friction components.

[0016] This provides a foundation for low-cost preparation while also taking into account economic efficiency.

[0017] In the composition design of this invention, elements such as Fe, Ni, Cr, Mn, Si, Mo, and Sn can be provided from the scraps of tin-plated copper-steel composite strips (e.g., Fe, Ni, and Cr from the stainless steel layer, and Sn from the tin-plated layer on the strip surface). Only a small amount of pure metal or master alloy (e.g., Si with Cu-20Si master alloy, Mo with Cu-10Mo master alloy) needs to be added to adjust the composition, without relying on large amounts of expensive pure metal raw materials (e.g., avoiding the extensive use of high-cost elements such as Co and rare earth elements in traditional lead-free copper alloys). This raw material source design can significantly reduce the cost of alloy raw materials, while solving the problem of recycling scraps from tin-plated copper-steel composite strips, achieving the dual goals of resource recycling and cost control, enabling the alloy to possess excellent performance while maintaining market competitiveness.

[0018] According to some embodiments of the present invention, the components, by mass percentage, include: Al: 12-15%, Fe: 2-4.5%, Ni: 1-2%, Cr: 1-2%, Mn: 0.1-0.2%, Sn: 0.1-0.2%, Si: 0.1-0.15%, Mo: 0.05-0.1%, The balance is Cu.

[0019] A second aspect of the present invention provides a method for preparing a high-strength, wear-resistant, lead-free copper alloy according to the first aspect of the present invention, comprising the following steps: S1: According to the formula, the raw materials are melted, kept at a certain temperature, and then cast to obtain an ingot; S2: The ingot is heated and then hot-extruded. The hot-extruded material is then subjected to solution annealing and aging annealing in sequence.

[0020] One of the technical solutions of this invention for preparing high-strength, wear-resistant, lead-free copper alloys has at least the following beneficial effects: The preparation method of the present invention does not require expensive equipment and complex process control, the reaction conditions are not harsh, the raw materials are readily available, the production cost is low, and it is easy to industrialize.

[0021] In the raw materials for preparing low-cost, high-strength, wear-resistant lead-free copper alloys, Cu is cathode electrolytic copper; Al is added in the form of aluminum ingots. To reduce alloy costs, the Fe, Ni, Cr, Sn, Mn, Si, and Mo elements required in the wear-resistant lead-free copper alloys are obtained from scraps of copper-steel composite strips. Sn originates from the tin plating layer on the surface of the copper-steel composite strip. When adjusting the composition, Fe, Ni, Cr, Sn, and Mn are added in pure metallic form, Si is added in the form of a Cu-20Si master alloy, and Mo is added in the form of a Cu-10Mo master alloy.

[0022] The steel layer of the copper-steel composite strip includes 304 stainless steel, 340 stainless steel, 316 stainless steel, 430 stainless steel, etc. The scraps of the copper-steel composite strip are successively immersed in a degreasing agent solution and then in clean water to remove surface oil. After being removed, they are placed in a hot air drying oven to dry the surface moisture, and then used as raw materials for later use.

[0023] According to some embodiments of the present invention, the melting temperature is 1050-1150°C.

[0024] According to some embodiments of the present invention, the melting temperature is any value among 1050°C, 1060°C, 1070°C, 1080°C, 1090°C, 1100°C, 1110°C, 1120°C, 1130°C, and 1140°C, such as 1080°C, or a range formed by any two, such as 1110°C-1130°C.

[0025] After all the raw materials have melted, a layer of crushed charcoal is placed on the surface of the melt to isolate oxygen and prevent oxidation of the melt.

[0026] According to some embodiments of the present invention, in step S1, after the raw material is melted, a refining agent is added, the mixture is stirred, and the slag is removed. Then, the mixture is kept at a temperature of 1050-1100°C.

[0027] According to some embodiments of the present invention, in step S1, after the raw material is melted, a refining agent is added, the mixture is stirred, and the slag is removed. Then, the material is kept at a temperature of any value among 1050℃, 1060℃, 1070℃, 1080℃, 1090℃, and 1100℃, such as 1080℃, or any range formed by both, such as 1060℃-1090℃.

[0028] According to some embodiments of the present invention, in step S1, after the raw material is melted, a refining agent is added, the mixture is stirred, and the slag is removed. Then, the mixture is kept at a constant temperature for 5-10 minutes.

[0029] According to some embodiments of the present invention, in step S1, after the raw material is melted, a refining agent is added, the mixture is stirred and the slag is removed, and then the mixture is kept at a certain temperature for a time of 5 min, 6 min, 7 min, 8 min, 9 min, or 10 min, such as 8 min, or any range of both, such as 6 min to 9 min.

[0030] After heat preservation, the melt is poured into a graphite mold to obtain a cylindrical ingot, the size of which can be φ145mm×550mm.

[0031] According to some embodiments of the present invention, in step S1, smelting can be carried out in a medium-frequency induction furnace.

[0032] During smelting, the order of adding materials is as follows: first, add electrolytic copper; after the electrolytic copper melts, add scrap copper-steel composite strip; and finally, add aluminum ingots. After refining, test the melt composition. Based on the difference between the test results and the designed composition, supplement elements such as Fe, Ni, Cr, Sn, Mn, Si, and Mo.

[0033] Before hot extrusion, milling is used to remove defects and oxide scale from the surface of the ingot.

[0034] When milling surface defects and oxide scale from ingots, the milling depth should be greater than 2 mm, and the surface after milling should be free of defects such as oxide scale, cold shuts, and micropores. At the same time, the ingot head and tail should be removed.

[0035] According to some embodiments of the present invention, the temperature of the hot extrusion is 850-950°C.

[0036] According to some embodiments of the present invention, the temperature of the hot extrusion is any value among 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, and 950°C, such as 880°C, or any range formed by both, such as 870°C-920°C.

[0037] According to some embodiments of the present invention, the hot extrusion speed is 10-15 mm / s.

[0038] According to some embodiments of the present invention, the hot extrusion speed is any value among 10 mm / s, 11 mm / s, 12 mm / s, 13 mm / s, 14 mm / s, and 15 mm / s, such as 10 mm / s, or any range of two such as 12 mm / s-14 mm / s.

[0039] According to some embodiments of the present invention, the extrusion ratio of the hot extrusion is 50-300.

[0040] According to some embodiments of the present invention, the extrusion ratio of the hot extrusion is any value among 50, 80, 100, 120, 150, 180, 200, 220, 250, 280, and 300, such as 80, or a range of any two, such as 80-150.

[0041] After the ingot is extruded from the die, ensure the surface temperature is between 750-820℃. Before extrusion, apply lubricating oil evenly to the inner wall of the extrusion cylinder to reduce extrusion friction. After hot extrusion, quickly transfer the alloy to an electric resistance furnace for solution annealing, followed by aging annealing.

[0042] The purpose of hot extrusion is to eliminate potential casting defects, such as voids and microcracks. Hot extrusion also breaks down coarse cast grains, allowing for dynamic recrystallization to produce a mixed microstructure where fine equiaxed recrystallized grains coexist with deformed grains. Low hot extrusion temperatures (e.g., below 850°C) and slow extrusion speeds can cause the temperature of the remaining ingot to drop to its brittle temperature range in the later stages of extrusion, leading to cracking of the alloy. Excessive extrusion temperatures can cause the ingot to overheat. When the extrusion ratio is less than 50, the cast microstructure in the central region of the ingot may be preserved. When the extrusion ratio is greater than 300, the required extrusion pressure may exceed the maximum extrusion pressure of the extruder, causing the extrusion process to be interrupted and the ingot to become stuck in the extrusion die. Excessively fast extrusion speeds cause a rapid increase in extrusion pressure and the accumulation of a large amount of deformation heat, which may lead to overheating and cracking of the ingot.

[0043] According to some embodiments of the present invention, the solution annealing temperature is 850-950°C.

[0044] According to some embodiments of the present invention, the solution annealing temperature is any value among 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, and 950°C, such as 850°C, or a range formed by any two, such as 870°C-920°C.

[0045] According to some embodiments of the present invention, the solution annealing time is 0.5-4 hours.

[0046] According to some embodiments of the present invention, the solution annealing time is any value among 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, and 4h, such as 2h, or a range of any two, such as 1h-3h.

[0047] According to some embodiments of the present invention, the aging annealing temperature is 450-550°C.

[0048] According to some embodiments of the present invention, the aging annealing temperature is any value among 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, and 550°C, such as 450°C, or a range formed by any two, such as 470°C-520°C.

[0049] According to some embodiments of the present invention, the aging annealing time is 1-6 hours.

[0050] According to some embodiments of the present invention, the aging annealing time is any value among 1h, 2h, 3h, 4h, 5h, and 6h, such as 2h, or a range of any two, such as 2h-4h.

[0051] Because the grain size and distribution of various phases are uneven in the alloy after hot extrusion, the mechanical properties of the extruded billet are not uniform. Therefore, solution annealing and aging annealing are necessary. The purpose of solution annealing is to allow the unevenly distributed phases formed in the as-cast structure to recrystallize back into the matrix, while recrystallizing to form strain-free equiaxed crystals. The purpose of aging annealing is to allow various dissolved atoms to precipitate again, forming uniformly distributed precipitates, thereby improving the mechanical properties of the alloy. If the solution temperature is too low and the time is too short, the phases in the alloy after hot extrusion may not be fully dissolved, and recrystallization may be incomplete, failing to achieve the desired effect. On the other hand, if the solution temperature is too high and the time is too long, it will lead to coarse grains, severely reducing the strengthening effect of fine grains. The selection of aging temperature and aging time is based on the principle that the precipitates are fully precipitated and finely dispersed.

[0052] According to some embodiments of the present invention, the cooling method after the aging annealing is air cooling.

[0053] A third aspect of the invention provides the application of high-strength, wear-resistant, lead-free copper alloys in the manufacture of transmission or friction components.

[0054] Transmission and friction components (such as automotive valve guides, nuclear power equipment worm gears, and high-speed punch press guide sleeves) are often subjected to heavy loads, high-frequency friction, high temperatures, or corrosive environments. This high-strength, wear-resistant, lead-free copper alloy, with its multi-element synergistic strengthening system, can provide stable support for these components. On one hand, the synergistic effect of multiple high-hardness and wear-resistant phases, including the α phase (copper-based solid solution), β' phase (Cu3Al, stable at 325℃ with high strength and hardness), γ2 phase (Cu9Al4, microhardness 500-600HV), and κ phase (FeAl / FeAl3), results in a component hardness ≥350HV and tensile strength ≥850M. Pa can withstand heavy loads and impact loads, preventing components from deforming or breaking due to insufficient mechanical properties. On the other hand, the Al element promotes the formation of an Al2O3-Cu2O composite oxide film on the surface of the component. Al2O3 is dense and chemically stable, which can isolate the direct contact between metals at the friction interface to resist adhesive wear. Cu2O has lubricating properties and can reduce the coefficient of friction (≤0.15). At the same time, the Mo element inhibits the coarsening of the wear-resistant phase. Combined with Fe and Cr to form intermetallic compounds, it significantly improves the component's resistance to long-term frictional wear and extends its service life. It is especially suitable for harsh working conditions such as high radiation in the nuclear power field and high temperature and heavy load in engineering machinery.

[0055] Traditional lead-containing copper alloys (such as CuZn37Mn3Al2PbSi) commonly used in transmission / friction components are prone to lead leaching during production, processing, and long-term service. This not only pollutes soil and water sources but also poses health risks to production personnel and end users through wear dust or contact transmission. In contrast, this lead-free copper alloy completely eliminates lead in its composition design. Transmission / friction components made from this alloy meet the limits for harmful elements in mainstream environmental regulations, avoiding secondary environmental pollution and eliminating the potential health risks of lead. It is suitable for fields with extremely high environmental and health requirements, such as automobiles and medical equipment, and helps downstream equipment achieve green upgrades.

[0056] The alloy's composition design is highly compatible with preparation processes such as hot extrusion and solution aging. Hot extrusion can eliminate casting defects and refine grains, ensuring the quality of component forming. Solution aging can cause the strengthening phase to precipitate uniformly, further optimizing the mechanical properties of the component. It can meet the processing requirements of complex shapes of transmission / friction components (such as the hollow structure of guide sleeves and the tooth shape of gears), avoiding processing cracks caused by high material brittleness or insufficient plasticity.

[0057] The alloy can utilize scraps from copper-steel composite strips to provide key elements such as Fe, Ni, Cr, and Mn, eliminating the need for large quantities of expensive pure metal raw materials and significantly reducing raw material costs. Simultaneously, the recycling of these scraps solves the problem of industrial waste disposal, reducing resource waste. This cost advantage makes transmission / friction components made from this alloy more competitive in the market, particularly suitable for mass production in the automotive and construction machinery industries, thus promoting their large-scale application.

[0058] Failures in transmission and friction components often stem from excessive wear or degradation of mechanical properties. Components made from this alloy are not only wear-resistant and high-strength, but also possess excellent environmental adaptability: Mn enhances the alloy's corrosion resistance, protecting components from corrosion and aging in lubricating oil or humid environments; Sn inhibits melt oxidation, ensuring compositional uniformity after component forming and reducing early failures caused by localized weaknesses. Improved long-term service stability reduces maintenance frequency and replacement costs for downstream equipment, minimizing downtime losses and ensuring efficient equipment operation. Detailed Implementation

[0059] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0060] In some embodiments of the present invention, a high-strength, wear-resistant, lead-free copper alloy is provided, comprising, by weight percentage: Al: 5-15%, Fe: 2-5%, Ni: 1-3%, Cr: 1-3%, Mn: 0.1-0.5%, Sn: 0.05-0.2%, Si: 0.1-0.2%, Mo: 0.05-0.2%, The balance is Cu.

[0061] Al: When Al is the main alloying element in copper, the alloy mainly consists of α, β', and γ2 phases. The α phase is a copper-based solid solution. The β' phase, with the chemical formula Cu3Al, is stable at 325℃ and exhibits high strength and hardness. The γ2 phase, with the chemical formula Cu9Al4, is a hard and brittle phase with a hardness far exceeding that of the matrix, reaching a microhardness of 500-600 HV. The α, β', and γ2 phases are key strengthening phases for the wear resistance of Al bronze. However, it is important to note that coarse γ2 phases can make the alloy brittle, and this should be avoided. Furthermore, when Al bronze is used in atmospheric, water, or lubricating oil environments, a dense composite oxide film composed of Al2O3 and a small amount of Cu2O will spontaneously form on its surface. Al2O3 has extremely high hardness, strong chemical stability, and a dense structure (without significant pores), effectively isolating direct metal-metal contact at the friction interface and preventing adhesive wear between metals. Cu2O has low hardness but certain lubricity, which can reduce the coefficient of friction between the oxide film and the mating parts. When the surface oxide film is locally broken due to wear, the exposed fresh surface will quickly react with O2 in the air to regenerate an Al2O3-Cu2O composite film. This self-healing ability ensures the continuous protective effect of the oxide film.

[0062] Fe: When the Fe content in Al bronze exceeds 1 wt%, it will form a body-centered cubic FeAl and FeAl3 phases, collectively referred to as the κ phase. A suitable and uniformly distributed κ phase can improve the strength, hardness, and wear resistance of Al bronze. Additionally, adding Fe can refine the alloy grains, increasing the alloy's strength and hardness. However, when the Fe content exceeds 5 wt%, the alloy's corrosion resistance will significantly deteriorate; therefore, the Fe content is generally controlled within the range of 2-5%.

[0063] Ni: When the Ni content exceeds the solid solubility, it will form the NiAl phase with Ni. This phase has a structure similar to the κ phase and can refine the grains, improving the hardness and wear resistance of Al bronze. Ni can also expand the α phase region and, to a certain extent, suppress the formation of a large number of coarse γ2 phases in the alloy, eliminating alloy brittleness.

[0064] Cr: Cr has low solid solubility in copper, and during the smelting and casting process, it forms fine Cr particles, which are distributed on the grain boundaries or inside the grains. In addition, a small amount of Cr can form fine intermetallic compounds with Fe and Al, which enhance the wear resistance of the alloy.

[0065] Mn: Mn can accumulate in the κ phase, increasing its hardness. Mn also has a solid solution strengthening effect and improves the corrosion resistance of the alloy. Another function of Mn is to form a high-hardness, wear-resistant Mn5Si3 phase with Si.

[0066] Sn: Sn can suppress the oxidation tendency of alloy melts at high temperatures. A small amount of Sn can also dissolve into the matrix, playing a role in solid solution strengthening. The corrosion resistance and hardness of the alloy are both improved.

[0067] Si: Forms hard silicides in alloys, improving their wear resistance. For example, it forms the wear-resistant Mn5Si3 phase with Mn. The lower the residual Si content, the better, provided sufficient silicide formation is achieved. The Mn5Si3 phase, as a primary phase, nucleates and grows during melting, exhibiting a high melting point and high-temperature stability. However, coarse Mn5Si3 phases tend to crack. Excess Si dissolves into the matrix, reducing the α-phase content and decreasing the alloy's plasticity.

[0068] Mo: The main function of adding Mo is to inhibit the coarsening of various wear-resistant phases during heat treatment. A secondary function is that a small amount of Mo can improve the corrosion resistance of the alloy in reducing media (such as dilute sulfuric acid).

[0069] In some embodiments of the present invention, the specific procedure for the friction experiment is as follows: The friction experiment is conducted on a CSM friction and wear testing machine at an environment of 25°C and 50% relative humidity. The test conditions are: the sample undergoes circular motion on the friction pair, with a applied pressure of 5 N, a sliding linear velocity of 1 m / s, and a sliding distance of 1800 m. The friction material is cold-rolled copper sheet with a hardness of approximately 100 HV. The sample used for testing is semi-circular, 5 mm thick, and 12 mm in diameter. The thickness direction of the sample is the same as the direction of the circular motion linear velocity. Each sample is tested 5 times, and the coefficient of friction is taken as the average value.

[0070] Traditional wear-resistant bronze often adds lead to improve machinability and wear resistance, but lead easily leaches during use, polluting soil and water sources and harming human health. Lead-free formulations eliminate lead pollution at the source, meeting various environmental standards. Only electrolytic copper and aluminum ingots, along with very small amounts of virgin Fe, Ni, Cr, Sn, Mn, Si, and Mo, are needed to adjust the composition. Fe, Ni, Cr, Sn, Mn, Si, and Mo are primarily provided by stainless steel scraps and a Sn-plated surface. Furthermore, the latent heat required for scrap smelting is 10%-15% lower than that of pure metals, significantly reducing raw material and production energy costs. It also solves the problem of difficult recycling of copper-steel composite strip scraps from the large connector market.

[0071] The high-strength, wear-resistant copper alloy of this invention incorporates multiple alloying elements and a suitable heat treatment process. These alloying elements form multiple high-hardness phases that synergistically strengthen the alloy, improving its wear resistance and stability. The alloy's overall properties are: hardness ≥350HV, tensile strength ≥850MPa, and elongation ≥1.5%. Under the test conditions of this patent, the coefficient of friction is ≤0.15.

[0072] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0073] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0074] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0075] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0076] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0077] Example 1 A high-strength, wear-resistant, lead-free copper alloy was prepared.

[0078] In this embodiment, the alloy composition is Cu-12Al-2.3Fe-1.3Ni-1.4Cr-0.1Sn-0.1Mn-0.1Si-0.1Mo, and the materials are prepared according to the composition. First, electrolytic copper is added to a medium-frequency induction melting furnace. After the electrolytic copper is completely melted, scrap copper-steel composite strip is added and pressed into the copper melt, and finally aluminum ingots are added. The melting temperature is 1100℃. After all the raw materials are melted, a refining agent is added, stirred, and slag is removed. The melt composition is tested, and based on the difference between the test results and the designed composition, pure Fe, pure Ni, pure Cr, pure Sn, pure Mn, Cu-20Si, and Cu-10Mo are added. The melt is held at 1080℃ for 8 minutes, during which a layer of crushed charcoal is evenly covered on the surface of the melt. After the holding period, the melt is poured into a graphite mold to obtain a cylindrical ingot with a diameter of φ145mm*550mm.

[0079] Milling is performed to remove surface defects and oxide scale from the ingot. The milling amount is 2.5 mm. After milling, there are no casting defects or oxide scale on the surface of the ingot. Finally, the ingot head and tail are removed.

[0080] Before hot extrusion, the ingot is heated to 880℃, the extrusion speed is 10mm / s, the extrusion ratio is 80, and the surface temperature of the ingot is maintained at 800℃ after extrusion. Before extrusion, lubricating oil is evenly applied to the inner wall of the extrusion cylinder to reduce the friction between the ingot and the extrusion cylinder during extrusion.

[0081] After hot extrusion, the alloy is transferred to a resistance furnace for solution annealing within 5 seconds. The solution annealing temperature is 850℃, and the solution time is 2 hours. Oil cooling is used for solution annealing quenching. The aging annealing temperature is 450℃, and the aging time is 2 hours. Air cooling is used for aging annealing quenching.

[0082] The mechanical and tribological properties of the aged alloy samples were tested, and the results are shown in Table 1.

[0083] Example 2 A high-strength, wear-resistant, lead-free copper alloy was prepared.

[0084] In this embodiment, the alloy composition is Cu-15Al-4.2Fe-1.4Ni-1.6Cr-0.1Sn-0.1Mn-0.15Si-0.1Mo, and the materials are prepared according to the composition. First, electrolytic copper is added to a medium-frequency induction melting furnace. After the electrolytic copper is completely melted, scrap copper-steel composite strip is added and pressed into the copper melt, and finally aluminum ingots are added. The melting temperature is 1100℃. After all the raw materials are melted, a refining agent is added, stirred, and slag is removed. The melt composition is tested, and based on the difference between the test results and the designed composition, pure Fe, pure Ni, pure Cr, pure Sn, pure Mn, Cu-20Si, and Cu-10Mo are added. The melt is held at 1080℃ for 8 minutes, during which a layer of crushed charcoal is evenly covered on the surface of the melt. After the holding period, the melt is poured into a graphite mold to obtain a cylindrical ingot with a diameter of φ145mm*550mm.

[0085] Milling is performed to remove surface defects and oxide scale from the ingot. The milling amount is 2.5 mm. After milling, there are no casting defects or oxide scale on the surface of the ingot. Finally, the ingot head and tail are removed.

[0086] Before hot extrusion, the ingot is heated to 880℃, the extrusion speed is 10mm / s, the extrusion ratio is 80, and the surface temperature of the ingot is maintained at 800℃ after extrusion. Before extrusion, lubricating oil is evenly applied to the inner wall of the extrusion cylinder to reduce the friction between the ingot and the extrusion cylinder during extrusion.

[0087] After hot extrusion, the alloy is transferred to a resistance furnace for solution annealing within 5 seconds. The solution annealing temperature is 850℃, and the solution time is 2 hours. Oil cooling is used for solution annealing quenching. The aging annealing temperature is 450℃, and the aging time is 2 hours. Air cooling is used for aging annealing quenching.

[0088] The mechanical and tribological properties of the aged alloy samples were tested, and the results are shown in Table 1.

[0089] Example 3 A high-strength, wear-resistant, lead-free copper alloy was prepared.

[0090] In this embodiment, the alloy composition is Cu-12Al-2.3Fe-1.3Ni-1.4Cr-0.2Sn-0.1Mn-0.1Si-0.1Mo, and the materials are prepared according to the composition. First, electrolytic copper is added to a medium-frequency induction melting furnace. After the electrolytic copper is completely melted, scrap copper-steel composite strip is added and pressed into the copper melt, and finally aluminum ingots are added. The melting temperature is 1100℃. After all the raw materials are melted, a refining agent is added, stirred, and slag is removed. The melt composition is tested, and based on the difference between the test results and the designed composition, pure Fe, pure Ni, pure Cr, pure Sn, pure Mn, Cu-20Si, and Cu-10Mo are added. The melt is held at 1080℃ for 8 minutes, during which a layer of crushed charcoal is evenly covered on the surface of the melt. After the holding period, the melt is poured into a graphite mold to obtain a cylindrical ingot with a diameter of φ145mm*550mm.

[0091] Milling is performed to remove surface defects and oxide scale from the ingot. The milling amount is 2.5 mm. After milling, there are no casting defects or oxide scale on the surface of the ingot. Finally, the ingot head and tail are removed.

[0092] Before hot extrusion, the ingot is heated to 880℃, the extrusion speed is 12mm / s, and the extrusion ratio is 150. After extrusion, the surface temperature of the ingot is maintained at 800℃. Before extrusion, lubricating oil is evenly applied to the inner wall of the extrusion cylinder to reduce the friction between the ingot and the extrusion cylinder during extrusion.

[0093] After hot extrusion, the alloy is transferred to a resistance furnace for solution annealing within 5 seconds. The solution annealing temperature is 850℃, and the solution time is 2 hours. Oil cooling is used for solution annealing quenching. The aging annealing temperature is 450℃, and the aging time is 2 hours. Air cooling is used for aging annealing quenching.

[0094] The mechanical and tribological properties of the aged alloy samples were tested, and the results are shown in Table 1.

[0095] Example 4 A high-strength, wear-resistant, lead-free copper alloy was prepared.

[0096] In this embodiment, the alloy composition is Cu-12Al-2.3Fe-1.3Ni-1.4Cr-0.2Sn-0.1Mn-0.1Si-0.1Mo, and the materials are prepared according to the composition. First, electrolytic copper is added to a medium-frequency induction melting furnace. After the electrolytic copper is completely melted, scrap copper-steel composite strip is added and pressed into the copper melt, and finally aluminum ingots are added. The melting temperature is 1100℃. After all the raw materials are melted, a refining agent is added, stirred, and slag is removed. The melt composition is tested, and based on the difference between the test results and the designed composition, pure Fe, pure Ni, pure Cr, pure Sn, pure Mn, Cu-20Si, and Cu-10Mo are added. The melt is held at 1080℃ for 8 minutes, during which a layer of crushed charcoal is evenly covered on the surface of the melt. After the holding period, the melt is poured into a graphite mold to obtain a cylindrical ingot with a diameter of φ145mm*550mm.

[0097] Milling is performed to remove surface defects and oxide scale from the ingot. The milling amount is 2.5 mm. After milling, there are no casting defects or oxide scale on the surface of the ingot. Finally, the ingot head and tail are removed.

[0098] Before hot extrusion, the ingot is heated to 880℃, the extrusion speed is 10mm / s, the extrusion ratio is 80, and the surface temperature of the ingot is maintained at 800℃ after extrusion. Before extrusion, lubricating oil is evenly applied to the inner wall of the extrusion cylinder to reduce the friction between the ingot and the extrusion cylinder during extrusion.

[0099] After hot extrusion, the alloy is transferred to a resistance furnace for solution annealing within 5 seconds. The solution annealing temperature is 850℃, and the solution time is 2 hours. Oil cooling is used for solution annealing quenching. The aging annealing temperature is 475℃, and the aging time is 2 hours. Air cooling is used for aging annealing quenching.

[0100] The mechanical and tribological properties of the aged alloy samples were tested, and the results are shown in Table 1.

[0101] Example 5 A high-strength, wear-resistant, lead-free copper alloy was prepared.

[0102] In this embodiment, the alloy composition is Cu-12Al-2.3Fe-1.3Ni-1.4Cr-0.2Sn-0.1Mn-0.1Si-0.1Mo, and the materials are prepared according to the composition. First, electrolytic copper is added to a medium-frequency induction melting furnace. After the electrolytic copper is completely melted, scrap copper-steel composite strip is added and pressed into the copper melt, and finally aluminum ingots are added. The melting temperature is 1100℃. After all the raw materials are melted, a refining agent is added, stirred, and slag is removed. The melt composition is tested, and based on the difference between the test results and the designed composition, pure Fe, pure Ni, pure Cr, pure Sn, pure Mn, Cu-20Si, and Cu-10Mo are added. The melt is held at 1080℃ for 8 minutes, during which a layer of crushed charcoal is evenly covered on the surface of the melt. After the holding period, the melt is poured into a graphite mold to obtain a cylindrical ingot with a diameter of φ145mm*550mm.

[0103] Milling is performed to remove surface defects and oxide scale from the ingot. The milling amount is 2.5 mm. After milling, there are no casting defects or oxide scale on the surface of the ingot. Finally, the ingot head and tail are removed.

[0104] Before hot extrusion, the ingot is heated to 880℃, the extrusion speed is 10mm / s, the extrusion ratio is 80, and the surface temperature of the ingot is maintained at 800℃ after extrusion. Before extrusion, lubricating oil is evenly applied to the inner wall of the extrusion cylinder to reduce the friction between the ingot and the extrusion cylinder during extrusion.

[0105] After hot extrusion, the alloy is transferred to a resistance furnace for solution annealing within 5 seconds. The solution annealing temperature is 850℃, and the solution time is 2 hours. Oil cooling is used for solution annealing quenching. The aging annealing temperature is 550℃, and the aging time is 2 hours. Air cooling is used for aging annealing quenching.

[0106] The mechanical and tribological properties of the aged alloy samples were tested, and the results are shown in Table 1.

[0107] Table 1 Mechanical and tribological properties of wear-resistant copper alloys

[0108] As can be seen from Table 1, the performance data of all five embodiments meet or exceed the core indicators of the invention design (hardness ≥350HV, tensile strength ≥850MPa, elongation ≥1.5%, coefficient of friction ≤0.15), specifically as follows: Regarding hardness: the range is 357-396 HV, with the lowest value (Example 5, 357 HV) being higher than the 350 HV standard, and the highest value (Example 2, 396 HV) being 13.1% higher than the standard; Regarding tensile strength: the range is 877-967 MPa, with the lowest value (Example 5, 877 MPa) exceeding the 850 MPa standard, and the highest value (Example 2, 967 MPa) being 13.8% higher than the standard; Regarding elongation: the range is 1.5-2.7%, and the lowest value (Example 4, 1.5%) just meets the lower limit requirement of ≥1.5%, with no risk of fracture or plastic failure; Regarding the coefficient of friction: the range is 0.121-0.145, all of which are lower than the standard of 0.15. The lowest value (Example 2, 0.121) is 19.3% lower than the standard.

[0109] This indicates that the composition design (lead-free multi-element synergy) and preparation process (hot extrusion + solution aging) of the present invention are stable and can stably produce copper alloys that meet the requirements of high strength and wear resistance, providing performance support for transmission / friction component applications.

[0110] By combining the differences in composition and process among the five embodiments (such as Al content, Sn content, extrusion ratio, and aging temperature), the specific impact of these variables on performance can be further observed: First, the increased Al content significantly enhances hardness and tensile strength, but slightly reduces elongation.

[0111] Comparing Example 1 (Al=12%) and Example 2 (Al=15%): The processes for both are completely identical (extrusion ratio 80, aging temperature 450℃), with the only difference being the Al content; Hardness: 362 HV with 12% Al → 396 HV with 15% Al, an increase of 9.4%; Tensile strength: 896 MPa with 12% Al → 967 MPa with 15% Al, an increase of 8.1%; Elongation: 2.6% at 12% Al → 1.8% at 15% Al, a decrease of 30.8%.

[0112] Principle: Al is the core forming element of β' phase and γ2 phase (Cu9Al4, microhardness 500-600HV) in alloys. Increasing the Al content will increase the precipitation of high hardness strengthening phase, thereby enhancing hardness and strength; however, excessive Al will lead to an increase in the number of γ2 phase (hard and brittle phase), slightly sacrificing plasticity (elongation).

[0113] Secondly, increasing the extrusion ratio can slightly enhance hardness and tensile strength, while having little impact on elongation.

[0114] Comparing Example 3 (extrusion ratio 150) and Example 1 (extrusion ratio 80): the two have similar compositions (Al=12%, Sn=0.2%) and the same aging temperature (450℃), with the only difference being the extrusion ratio; Hardness: 362 HV at an extrusion ratio of 80 → 395 HV at an extrusion ratio of 150, an increase of 9.1%; Tensile strength: 896 MPa at an extrusion ratio of 80 → 956 MPa at an extrusion ratio of 150, an increase of 6.7%; Elongation: 2.6% at an extrusion ratio of 80 → 1.6% at an extrusion ratio of 150, a decrease of 38.5% (but still meets the ≥1.5% standard).

[0115] Principle: The higher the extrusion ratio, the more significant the effect of hot extrusion on breaking up coarse grains and eliminating casting defects (voids / microcracks) in the ingot, and the finer equiaxed grain structure can be formed; the strengthening effect of fine grains combined with the uniform distribution of strengthening phase further improves hardness and strength; the slight decrease in elongation is due to the increased deformation under high extrusion ratio, high residual dislocation density, and decreased plasticity, but it is still within the acceptable range.

[0116] Furthermore, as the aging temperature increases, the hardness and tensile strength tend to stabilize first and then decrease, while the elongation tends to decrease first and then increase.

[0117] Comparative Example 1 (aging at 450℃), Example 4 (aging at 475℃), and Example 5 (aging at 550℃): The three have the same composition (Al=12%, Sn=0.2%) and the same extrusion ratio (80), with only the aging temperature being different; Hardness: 362 HV at 450℃ → 386 HV at 475℃ (increase of 6.6%) → 357 HV at 550℃ (decrease of 7.5%); Tensile strength: 896MPa at 450℃ → 941MPa at 475℃ (increase of 5.0%) → 877MPa at 550℃ (decrease of 6.8%). Elongation: 2.6% at 450℃ → 1.5% at 475℃ (decreased by 42.3%) → 2.7% at 550℃ (increased by 80.0%).

[0118] Principle: The core of aging annealing is to allow atoms in the solid solution to precipitate and form fine and dispersed strengthening phases. At 450-475℃, the strengthening phases (β', γ2, κ phases) are fully precipitated and small in size, resulting in the best strengthening effect. At 550℃, which exceeds the optimal aging temperature, the precipitated strengthening phases begin to coarsen (dispersion decreases), the strengthening effect weakens, and the hardness and strength decrease. At the same time, high-temperature aging will alleviate the stress concentration inside the alloy and reduce the dislocation density, causing the plasticity (elongation) to recover, forming an inverse correlation of decreasing strength and increasing plasticity.

[0119] It can also be seen that the core role of Sn content is to assist in optimization.

[0120] Comparing Example 1 (Sn=0.1%) and Example 3 (Sn=0.2%): Both have the same Al content (12%) and aging temperature (450℃), only the Sn content and extrusion ratio differ (Example 3 has a higher extrusion ratio). If the effect of extrusion ratio is ignored, after Sn increases from 0.1% to 0.2%, the increase in hardness (362HV→395HV) and tensile strength (896MPa→956MPa) is mainly due to the increase in extrusion ratio. The auxiliary effect of Sn (inhibition of oxidation, slight solid solution strengthening) does not show significant performance differences. Principle: The designed content of Sn in the alloy is 0.05-0.2%, which is a trace auxiliary element. Its core function is to inhibit the high-temperature oxidation of the melt and ensure the uniformity of composition, rather than a major strengthening element. Therefore, it has a weak effect on macroscopic mechanical properties and frictional properties.

[0121] In summary, the following conclusions can be drawn: Synergy between composition and process is key to achieving high strength and wear resistance: Al content (12-15%) is the core regulating factor for hardness and tensile strength, extrusion ratio (80-150) can further improve performance through fine grain strengthening, and aging temperature (450-475℃) is the key window to ensure that the strengthening phase is fine and dispersed. The synergy of the three can make the alloy performance optimal (e.g., Example 2: Al=15%, extrusion ratio 80, aging 450℃, hardness 396HV, tensile strength 967MPa, friction coefficient 0.121, with the best comprehensive performance).

[0122] The performance-balanced design meets the needs of practical applications. The alloy achieves a balance between high strength and high wear resistance and basic plasticity. Even in Example 2 (high strength and high hardness), which has the best performance, the elongation is still 1.8% (higher than the lower limit of 1.5%), with no risk of brittle fracture. The coefficient of friction is below 0.15 for all components, which can effectively resist long-term wear of transmission / friction components and is suitable for the use of automotive valve guides, nuclear power worm gears and other applications.

[0123] The adjustability of process parameters provides room for personalized needs. If it is necessary to prioritize improving strength and wear resistance, a high Al content (15%) + a higher extrusion ratio (80-150) + a medium-low aging temperature (450-475℃) can be selected (as in Examples 2, 3, and 4); if it is necessary to improve plasticity (to facilitate subsequent processing) while ensuring basic strength, a medium Al content (12%) + a low extrusion ratio (80) + a high aging temperature (550℃) can be selected (as in Example 5). The flexibility of process parameters can be adapted to the performance preferences of different components.

[0124] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A high-strength, wear-resistant, lead-free copper alloy, characterized in that, By mass percentage, the components include: Al：5-15%， Fe: 2-5%, Ni: 1-3%, Cr：1-3%， Mn: 0.1-0.5%, Sn: 0.05-0.2%, Si: 0.1-0.2%, Mo: 0.05-0.2%, The balance is Cu.

2. The high-strength, wear-resistant, lead-free copper alloy according to claim 1, characterized in that, By mass percentage, the components include: Al：12-15%， Fe: 2-4.5%, Ni: 1-2%, Cr：1-2%， Mn: 0.1-0.2%, Sn: 0.1-0.2%, Si: 0.1-0.15%, Mo: 0.05-0.1%, The balance is Cu.

3. A method for preparing the high-strength, wear-resistant, lead-free copper alloy as described in claim 1 or 2, characterized in that, Includes the following steps: S1: According to the formula, the raw materials are melted, kept at a certain temperature, and then cast to obtain an ingot; S2: The ingot is heated and then hot-extruded. The hot-extruded material is then subjected to solution annealing and aging annealing in sequence.

4. The method according to claim 3, characterized in that, The melting temperature is 1050-1150℃.

5. The method according to claim 3, characterized in that, In step S1, after the raw materials are melted, a refining agent is added, the mixture is stirred, and the slag is removed. Then, the mixture is kept at a temperature of 1050-1100℃ for 5-10 minutes.

6. The method according to claim 3, characterized in that, The hot extrusion temperature is 850-950℃; and / or the hot extrusion speed is 10-15mm / s; and / or the hot extrusion ratio is 50-300.

7. The method according to claim 3, characterized in that, The solution annealing temperature is 850-950℃; and / or the solution annealing time is 0.5-4h.

8. The method according to claim 3, characterized in that, The aging annealing temperature is 450-550℃; and / or the aging annealing time is 1-6h.

9. The method according to claim 3, characterized in that, The cooling method after the aging annealing is air cooling.

10. The application of the high-strength, wear-resistant, lead-free copper alloy as described in claim 1 or 2 in the manufacture of transmission or friction components.

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