High-strength and high-wear-resistance beryllium-copper alloy for switches and preparation method thereof

Abstract

This invention discloses a high-strength, high-wear-resistant beryllium copper alloy for switches and its preparation method, belonging to the field of electronic component manufacturing technology. The alloy composition, by weight percentage, includes: Be: 1.80%–2.20%, Co: 1.50%–2.00%, Ni: 1.00%–1.60%, Si: 0.05%–0.10%, Cr: 0.05%–0.20%, Mg: 0.060%–0.080%, Y: 0.160%–0.220%, Ti(C,N): 0.30%–0.50%, Mo₂BC: 0.20%–0.40%, SiC: 0.050%–0.100%, Pb ≤ 0.005%, Sn ≤ 0.005%, other unavoidable impurity elements ≤ 0.01%, and the balance being Cu. The preparation method includes pretreatment of the nano-reinforcing phase by chemical copper plating, ultrasonic dispersion during smelting, followed by hot rolling, cold rolling, and secondary aging treatment. This invention significantly improves the alloy's strength and wear resistance through the synergistic effect of high Be strengthening and the nano-ceramic reinforcing phase. The finished product has a yield strength >1200MPa, tensile strength >1390MPa, elongation >3%, Rockwell hardness HRC >50, and wear rate <1.5×10⁻⁶. ‑4 mm 3 / N·m, suitable for high-reliability switching elements.

Description

Technical Field

[0001] This invention relates to the field of electronic component manufacturing technology, specifically to a high-strength, high-wear-resistant beryllium copper alloy for switches and its preparation method. Background Technology

[0002] In fields such as new energy vehicles, low-altitude economy, deep-sea and high-end industrial equipment, the reliability and lifespan of various switches and electrical connectors are crucial to the overall system operation. These devices, under conditions of frequent switching and high insertion / removal cycles, continuously endure mechanical stress and interface friction, posing a severe test to the strength and wear resistance of their core materials. Currently widely used beryllium copper faces significant limitations in long-term service. On the one hand, the material strength is prone to decay under high-frequency stress cycles, leading to plastic deformation or a decrease in resilience in elastic elements, directly affecting the stability of contact pressure and operational accuracy. On the other hand, insufficient surface wear resistance makes the material susceptible to wear, oxidation, or material transfer under the combined effects of mechanical friction and electrical contact, causing increased contact resistance and decreased signal quality, ultimately leading to functional failure. Decreased strength exacerbates surface damage, while surface wear weakens the effective load-bearing cross-section; these two mechanisms reinforce each other, accelerating the overall performance degradation of the components.

[0003] Therefore, to meet the urgent needs of high-reliability switches for long service life, high operational stability, and low failure rate, it is essential to develop novel beryllium copper alloys that combine high strength, high wear resistance, and good conductivity. Simultaneously, a matching and precisely controllable manufacturing process is required to achieve coordinated optimization of material microstructure, mechanical properties, and surface characteristics. This systematic breakthrough from material design to manufacturing process is the fundamental way to improve the mechanical durability and electrical contact reliability of switching devices, and also a crucial foundation for driving the development of high-end electrical systems towards longer lifespans and higher load conditions.

[0004] The patent application CN109706341A discloses a "cobalt-containing high-strength, high-hardness, and wear-resistant copper alloy and its preparation method." The copper alloy contains the following chemical element composition and mass percentages: Al 10.5-11.5%, Fe 5.5-6.5%, Ni 4.5-5.5%, Co 0.8-1.5%, Be 0.08-0.12%, Re 0.05-0.2%, with the balance being copper. This invention achieves a refined microstructure through the rational matching of elements, thereby improving the alloy's comprehensive properties such as strength, hardness, wear resistance, and plasticity. However, the total Al, Fe, and Ni content of this beryllium-containing aluminum bronze exceeds 20%, significantly reducing the alloy's electrical and thermal conductivity. The resulting brittle phase severely impairs the alloy's plasticity, greatly increasing the difficulty of processing.

[0005] The publication CN118006947A discloses a "high-hardness, wear-resistant, low-beryllium copper alloy and its preparation method," wherein the alloy composition is: Be 0.2-0.4 wt.%, Co 0.8-1.2 wt.%, with the remainder being Cu and impurities. This method mainly achieves grain refinement by introducing an externally enhanced ultrasonic field, combined with heat treatment strengthening, ultimately improving the wear resistance of the beryllium copper alloy. However, ultrasonic treatment has inherent technical limitations: the energy of the ultrasonic field in the melt attenuates with distance, making it difficult to achieve a uniform fine-grained effect across the entire surface for large-volume ingots, easily leading to differences in the microstructure and properties between the core and edges; ultrasonic parameters need precise control, and fluctuations in melt temperature and composition can affect the treatment effect, increasing the difficulty of its large-scale industrial production; the investment in high-power ultrasonic equipment and the long-term wear of the amplitude transformer in the high-temperature melt can also increase production costs.

[0006] The publication CN112281020A discloses a "wear-resistant copper alumina composite material and its preparation method." The copper alumina composite material comprises, by weight percentage, 3-5% graphite, 2.8-3.2% alumina particles, 0.8-1.2% alumina fibers, 0.2-0.3% lanthanum powder, with the balance being Cu and unavoidable impurities. This method uses hydrated aluminum sulfate as a raw material and polyethylene glycol as a surfactant to obtain alumina particles; alumina fibers are prepared by electrospinning, followed by mechanical mixing to obtain copper alumina composite powder, which is then sintered at high temperature via spark plasma to obtain the copper alumina composite material. However, the electrospinning preparation of alumina fibers has extremely low yield, is time-consuming, and costly. The stability of the precursor solution, the spinning environment, and the post-treatment process all severely affect the morphology, crystallinity, and defects of the fibers, leading to large batch-to-batch performance fluctuations. While adding up to 3-5% graphite lubricant is beneficial for wear resistance, it drastically disrupts the electrical conductivity continuity of the copper matrix, resulting in a significant decrease in the electrical and thermal conductivity of the composite material.

[0007] The patent application CN119913394A, entitled "A Novel Heat-Resistant and Wear-Resistant Copper Alloy and Its Application," describes a novel heat-resistant and wear-resistant copper alloy with the following composition and mass percentages: zinc: 35%~42%, aluminum: 2%~4%, manganese: 4%~7%, nickel: 0.4%~0.7%, silicon-chromium-iron alloy: 4%~7%, and the remainder being copper. This method improves the wear resistance and strength of the copper alloy by optimizing its composition, proportions, and preparation process. However, the high zinc content (35%~42%) of this alloy is prone to severe component segregation and microstructure inconsistency under high-speed centrifugal force, leading to significant differences in composition, hardness, and wear resistance at different locations in the casting. Simultaneously, zinc's low boiling point exacerbates volatilization and oxidation during casting, easily forming porosity and inclusion defects, damaging the integrity and surface quality of the casting. Furthermore, centrifugal casting is limited to producing symmetrical parts such as cylindrical and annular shapes, resulting in a limited product range that cannot meet the needs of mass production and low-cost manufacturing of complex components.

[0008] Currently, beryllium copper alloys struggle to maintain their high strength and wear resistance under extreme mechanical loads and frictional wear conditions, leading to accelerated degradation of their core properties, a critical challenge that urgently needs to be overcome. This not only directly increases the risk of contact failure but also constitutes a core bottleneck restricting the long-life, high-precision operation of highly reliable switching components. Summary of the Invention

[0009] The purpose of this invention is to provide a novel high-strength and high-wear-resistant beryllium copper alloy. By controlling the precise balance of composition and structure, this alloy ensures good strength and wear resistance under harsh working conditions of strong electrothermal shock and mechanical wear, fundamentally solving the core requirements of high-reliability switches for contact performance and long service life.

[0010] The technical solution of this invention: A high-strength, high-wear-resistant beryllium copper alloy for switches, whose chemical composition by weight percentage includes: Be: 1.80%–2.20%, Co: 1.50%–2.00%, Ni: 1.00%–1.60%, Si: 0.05%–0.10%, Cr: 0.05%–0.20%, Mg: 0.060%–0.080%, Y: 0.160%–0.220%, Ti(C,N): 0.30%–0.50%, Mo2BC: 0.20%–0.40%, SiC: 0.050%–0.100%, Pb≤0.005%, Sn≤0.005%, other unavoidable impurity elements ≤0.01%, and the balance being Cu.

[0011] Furthermore, the beryllium copper alloy is processed into a thin strip with high strength and high wear resistance for switching, and the thickness of the thin strip is 0.5mm to 2.0mm.

[0012] Furthermore, the strip material meets the following performance indicators: yield strength > 1200 MPa, tensile strength > 1390 MPa, elongation > 3%, Rockwell hardness HRC > 50, and wear rate < 1.5 × 10⁻⁶. -4 mm 3 / N·m.

[0013] Furthermore, the raw materials of the chemical composition are as follows: oxygen-free copper, Cu-25%Be master alloy, electrolytic cobalt, electrolytic nickel, electrolytic chromium, Cu-18%Si master alloy, Mg-30%Cu master alloy, Cu-20%Y master alloy, and Ti(C,N), Mo2BC, and SiC are respectively selected as Ti(C,N) nanoparticles with a particle size of 30nm to 50nm, Mo2BC nanoparticles with a particle size of 50nm to 100nm, and SiC nanofibers with a diameter of 200nm to 500nm and an aspect ratio of 10 to 20.

[0014] A method for preparing a high-strength, high-wear-resistant beryllium copper alloy for switches includes the following steps: Step 1: Metallization pretreatment of the reinforcing phase. Ti(C,N) nanoparticles, Mo2BC nanoparticles and SiC nanofibers are chemically plated with copper to form a copper coating layer on the particle surface, thus obtaining metallized reinforced powder. The chemical copper plating process includes the following steps: the particles are sequentially subjected to alkaline washing to remove oil, acid washing to roughen, SnCl2-HCl solution sensitization, palladium chloride solution activation, and then plating is performed in the chemical copper plating solution. During the plating process, mechanical stirring and intermittent ultrasonication are used. The plating solution consists of CuSO4·5H2O, potassium sodium tartrate, formaldehyde, and 2,2'-bipyridine, and the pH of the solution is adjusted with NaOH. Step 2: Batching, weigh the alloy raw materials and the metallized reinforcing powder obtained in Step 1 according to the alloy chemical composition weight percentage of claim 1; Step 3: Melting and Ultrasonic Dispersion: The alloy raw materials are placed in a vacuum induction furnace for melting and refining. The melting is carried out at 1220℃~1250℃ until completely melted. The temperature is then raised to 1450℃~1480℃ for a first refining for 15min~20min. Subsequently, metallized reinforcing powder is added to achieve secondary feeding. A vibrating amplitude transformer is inserted into the melt for ultrasonic treatment. The vibration frequency of the ultrasonic treatment is 30kHz and the treatment time is 10min to make the reinforcing powder uniformly dispersed. Finally, the temperature is lowered to 1120℃~1150℃ and water-cooled to obtain the beryllium copper alloy billet.

[0015] Step 4: Thermomechanical processing and heat treatment. The billet from Step 3 is subjected to homogenization treatment, hot rolling, annealing, solution treatment, cold rolling, and aging treatment in sequence to obtain beryllium copper alloy strip.

[0016] Furthermore, the homogenization treatment in step 4 is carried out at a temperature of 850℃~880℃ for 20h~30h.

[0017] Furthermore, the total processing rate of hot rolling in step 4 is 90% to 95%, wherein the roughing temperature is 880℃ to 900℃ and the finishing temperature is 750℃ to 780℃.

[0018] Furthermore, the annealing process in step 4 involves holding the hot-rolled plate at 800℃~820℃ for 4h~8h and then air-cooling it to obtain the annealed plate.

[0019] Further, the solution treatment in step 4 involves holding the annealed plate at 880℃~900℃ for 1h~2h and then forcibly cooling it. Furthermore, in step 4, the cold rolling includes two cold rolling processes and intermediate annealing. The total processing rate of the first cold rolling is 80% to 90%, the intermediate annealing temperature is 320℃ to 350℃, and the holding time is 2h to 4h. The total processing rate of the second cold rolling is 45% to 65%, the intermediate annealing temperature is 400℃ to 420℃, and the holding time is 6h to 8h.

[0020] Furthermore, the aging treatment described in step 4 is a two-stage aging treatment. The first-stage aging temperature is 320℃~340℃, and the holding time is 2h~4h. The second-stage aging temperature is 380℃~400℃, and the holding time is 6h~8h.

[0021] The beneficial effects of this invention: This invention adopts the design concept of "high Be primary strengthening + nickel-cobalt secondary strengthening + microalloying regulation + nano-ceramic reinforcement" to develop a beryllium copper alloy with both high strength and high wear resistance. The purpose of the high Be content design is to endow the alloy with excellent tensile strength and resistance to plastic deformation by precipitating more nano-reinforcing phases. Ni, Co, and Si elements further contribute to the matrix strength through solid solution and precipitation strengthening, while synergistically refining the size of precipitated phases and improving the uniformity of age-hardening response. Cr, Mg, and Y, as multi-element microalloying regulation elements, synergistically improve the matrix strength, toughness, and wear resistance by refining grains, purifying grain boundaries, dispersing high-hardness phases, and promoting the formation of a dense oxide film on the surface. Ti(C,N), Mo2BC ceramic particles, and SiC fibers constitute a nano-ceramic reinforcement system, with a high-hardness load-bearing skeleton resisting abrasive indentation and ploughing, significantly improving the alloy's load-bearing capacity and wear resistance. The present invention discloses a high-strength, high-wear-resistant beryllium copper alloy strip for switches, with the following specifications: thickness: 0.5mm ≤ T ≤ 2mm; yield strength > 1200MPa; tensile strength > 1390MPa; elongation > 3%; Rockwell hardness HRC > 50; and wear rate < 1.5 × 10⁻⁶. -4 mm 3 / N·m. The successful development of the alloy of this invention has achieved a simultaneous leap in alloy strength and wear resistance, fundamentally solving the common problem of premature failure of electrical contact materials under high load conditions, and laying a key material foundation for the long-life design of precision switching devices. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the specific 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.

[0023] Figure 1 This is a design strategy diagram for the beryllium copper alloy of the present invention. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0025] The high-strength, high-wear-resistant beryllium copper alloy for switches described in this invention has the following chemical composition by weight percentage: Be: 1.80%–2.20%, Co: 1.50%–2.00%, Ni: 1.00%–1.60%, Si: 0.05%–0.10%, Cr: 0.05%–0.20%, Mg: 0.060%–0.080%, Y: 0.160%–0.220%, Ti(C,N): 0.30%–0.50%, Mo2BC: 0.20%–0.40%, SiC: 0.050%–0.100%, Pb≤0.005%, Sn≤0.005%, other impurity elements ≤0.01%, balance Cu.

[0026] This invention optimizes the chemical composition of beryllium copper alloy: (1) Be is the most critical strengthening element in copper alloys, playing a decisive role in improving the strength and wear resistance of the alloy. It mainly improves the yield strength and macroscopic hardness of the alloy through solid solution strengthening and the formation of high-hardness Be-Cu intermetallic compound precipitates (mainly γ'', γ' and γ phases), laying a solid foundation for improving wear resistance. These dispersed nanoscale precipitates can effectively hinder dislocation movement, refine grains, and directly resist micro-cutting and plastic deformation of contact components as hard support points. At the same time, during the friction process, Be helps to promote the formation of a denser and more adherent Be-containing oxide film on the alloy surface, which can play the role of solid lubrication and diffusion barrier, thereby reducing the friction coefficient and inhibiting adhesion transfer between metals, significantly improving the ability to resist adhesive wear and fretting wear. However, excessive Be content will lead to coarsening of precipitates and excessive enrichment at grain boundaries, which may induce brittle spalling under cyclic loading or impact, thereby reducing wear resistance and reliability. Therefore, this invention adopts a "high Be" content design, strictly controlled within the range of 1.8% to 2.2%, to ensure that the alloy has sufficient strength and wear resistance, while avoiding the risk of embrittlement caused by excessive content.

[0027] (2) Co, as an important strengthening element in copper alloys, plays a crucial role in optimizing the alloy's strength and wear resistance. It primarily strengthens the matrix through solid solution strengthening and promoting the formation of finer, more stable precipitates. Co atoms dissolved in the copper lattice cause lattice distortion, directly contributing to strength; simultaneously, Co can regulate the diffusion behavior of Be, inhibiting excessive coarsening of the precipitates and making the Be-Cu strengthening phase distribution more dispersed and uniform, thereby significantly improving the age hardening effect and high-temperature microstructure stability of the alloy. These precipitated strengthening phases, together with Co itself, form a hard phase (Co, Cu). x Be y Together, they effectively hinder dislocation movement and resist abrasive indentation and cutting, providing the alloy with higher macroscopic hardness and resistance to plastic deformation. However, too low a Co content has limited effect, while too high a content may lead to the formation of brittle intermetallic compounds, which would impair toughness and increase cost. Therefore, this invention strictly controls the Co content within the range of 1.50% to 2.00%.

[0028] (3) Ni, as a key alloying element in copper alloys, makes a significant contribution to the strength and wear resistance of the alloy. Its strengthening mechanism is similar to that of Co. Ni atoms dissolve in the Cu matrix, producing a significant solid solution strengthening effect, which improves the strength and hardness of the alloy. In addition, Ni can effectively regulate the diffusion rate of Be atoms, inhibit the excessive growth of γ' and γ'' strengthening phases during aging, greatly enhance the precipitation strengthening effect of the alloy, improve the microstructure stability and deformation resistance of the alloy, thereby improving wear resistance. However, if the Ni content is too low, the strengthening effect is limited, while if the content is too high, it will not only impair the cold working performance of the alloy, but may also affect the toughness due to the formation of too many brittle phases, and significantly increase the raw material cost. Therefore, the present invention strictly controls the Ni content within the range of 1.00% to 1.60%.

[0029] (4) Si is a key alloying strengthening element in this invention, and it has a significant effect on improving the strength and wear resistance of copper alloys. In terms of strength, Si can not only dissolve in the Cu matrix to cause lattice distortion, but also combine with Cu and Ni to form fine Cu3Si and Ni2Si strengthening phases respectively. The precipitated phase maintains a specific crystal orientation relationship with the matrix, which can generate an extremely strong coherent strain field, which strongly hinders dislocation movement, thereby providing a better strengthening effect. In terms of wear resistance, Si has the ability to modify the surface in situ. Under the activation of frictional heat, Si will selectively diffuse to the surface and oxidize, dynamically generating a surface layer mainly composed of amorphous SiO2, which effectively isolates the direct contact between the wear part and the matrix, transforming the severe intermetallic adhesive wear into a milder oxide film wear, thereby greatly reducing the wear rate. However, when the Si content is too low, its effect is weak, while when the content is too high, it will lead to excessive growth of the ordered phase, decline of the strengthening effect, and formation of coarse brittle silicides at the grain boundaries, which seriously damages the toughness and fatigue resistance of the alloy. Therefore, the Si content is strictly controlled within the range of 0.05% to 0.10% in this invention.

[0030] (5) Cr is an effective alloying strengthening element in copper alloys, playing an important role in enhancing the strength, hardness, and wear resistance of the alloy. Cr has extremely low solid solubility in the Cu matrix, and during aging treatment, it precipitates as fine, dispersed chromium-rich phases, which pin dislocations and hinder grain boundary movement, significantly improving the yield strength of the alloy. In terms of wear resistance, these high-hardness precipitates act as strengthening particles, directly resisting the indentation and ploughing of abrasives, effectively reducing adhesive wear. In addition, Cr can promote the formation of a Cr2O3 protective layer on the alloy surface, which is dense, chemically stable, has strong adhesion, and high hardness, serving as an excellent anti-wear and anti-corrosion barrier, significantly reducing the material loss rate during friction. However, excessive Cr can lead to excessive coarsening or agglomeration of the precipitates, not only reducing the strengthening effect but also impairing the toughness of the alloy. Therefore, this invention strictly controls the Cr content within the range of 0.05% to 0.20%.

[0031] (6) Mg is an alloying element in copper alloys that is primarily strengthened by solid solution and also has the function of regulating microstructure. It plays a unique role in improving strength and wear resistance. In terms of strength, Mg dissolves significantly into the Cu matrix due to its atomic size effect, producing strong lattice distortion. Due to its extremely low stacking fault energy, it greatly promotes the formation of nanotwins. These twin boundaries allow the alloy to achieve higher strength while maintaining good plasticity. In addition, Mg can precipitate in the form of fine intermetallic compounds (such as Cu2Mg) during aging. These nano-relatives produce a strong pinning effect on grain boundaries, which can effectively inhibit grain growth during hot working. In terms of wear resistance, Mg can significantly improve the matrix's resistance to indentation and cutting by refining the deformation band and twin bundle size. It can also promote the formation of a continuous, dense, and stable oxide film in the alloy during friction, thereby greatly reducing the tendency of adhesive wear. However, excessive Mg content can easily lead to grain boundary segregation, which can degrade the toughness of the alloy and increase the risk of hot working cracks. Therefore, the Mg content is strictly controlled within the range of 0.060% to 0.080% in this invention.

[0032] (7) Y is an important microalloying element in copper alloys, possessing both grain refinement and surface modification functions. It makes a unique contribution to improving the strength and wear resistance of the alloy. In terms of strength, trace amounts of Y form high-melting-point dispersed particles in the melt, which not only significantly refine the as-cast grains as heterogeneous nucleation nuclei, but also provide a large number of nucleation sites for the Be-Cu strengthening phase during aging, increasing the nucleation rate while refining the size of the precipitated phase. The synergistic effect of the two strengthening mechanisms greatly improves the yield strength and hardness of the alloy. In terms of wear resistance, Y can promote the formation of a dense composite oxide film on the alloy surface with strong adhesion to the matrix, further improving the anti-adhesion and anti-stripping ability. However, excessive Y content will lead to coarsening and agglomeration of Cu2Y or Y2O5 particles, and the formation of a brittle phase enrichment layer at the grain boundaries, which will instead rupture the matrix and induce stress concentration. Therefore, the present invention strictly controls the Y content within the range of 0.160% to 0.220%.

[0033] (8) Ti(C,N) nanoparticles are an important wear-resistant strengthening phase in this invention. Their contribution to improving the strength and wear resistance of copper alloys differs from that of traditional alloying elements, exhibiting heterogeneous phase interface strengthening characteristics. In terms of strength, the core mechanism of Ti(C,N) is not dissolution into the matrix lattice, but rather its existence as dispersed nanoscale hard particles within the grains or at grain boundaries, forming a semi-coherent interface with the Cu matrix. This interface exhibits high bonding strength and excellent thermal stability, effectively undertaking load transfer tasks. Furthermore, nano-Ti(C,N) can also serve as consistent particles in the nucleation process, increasing the nucleation rate during phase transformation / recrystallization and achieving a grain refinement strengthening effect. Simultaneously, when dislocations encounter these non-shearable nanoparticles, they must bypass them, leaving dislocation loops around the particles, thereby significantly increasing the strain hardening rate and yield strength. In terms of wear resistance, the inherent ultra-high hardness of Ti(C,N) nanoparticles allows them to act as a load-bearing skeleton at the friction interface, directly resisting the indentation and ploughing of abrasives, significantly inhibiting micro-cutting wear. Furthermore, under cyclic frictional heat and force, Ti(C,N) particles can promote the formation of a mechanically mixed layer rich in Ti, C, and N elements. This layer has high density and low friction characteristics, effectively isolating direct metal-to-metal contact between the wear pairs, thus transforming adhesive wear into mild oxidation and abrasive wear. Moreover, Ti(C,N) itself has good electrical conductivity, and this is maintained as much as possible while improving the alloy's strength and wear resistance. However, when the Ti(C,N) content is too low, the improvement in wear resistance is limited; when the content is too high, it easily leads to nanoparticle agglomeration, increased tendency for interface debonding, and the formation of a continuous brittle network at the grain boundaries, severely impairing the alloy's plasticity, fracture toughness, and fatigue spalling resistance. Therefore, this invention strictly controls the Ti(C,N) content within the range of 0.30% to 0.50%.

[0034] (9) Mo2BC nanoparticles are another key wear-resistant strengthening phase in this invention, and their effect on improving the strength and wear resistance of copper alloys is similar to that of TiC. In terms of strength, since Mo2BC has both high hardness and certain conductivity, the dispersed Mo2BC nanoparticles can form a heterogeneous phase interface with high bonding strength with the Cu matrix. Under load, the stress can be transferred from the soft matrix to the hard phase with high elastic modulus, and a strong pinning effect is generated on grain boundary migration, which significantly refines the copper matrix grains and synergistically improves the tensile properties of the alloy. This is its unique strengthening path. In terms of wear resistance, Mo2BC particles are exposed on the surface of the alloy during sliding friction and are induced to undergo oxidation reaction under the action of contact stress and frictional heat, generating a continuous and dense oxide film. This film can hinder the direct contact and adhesive wear between the metal matrix. At the same time, the particles themselves significantly improve the load-bearing capacity of the matrix and inhibit abrasive indentation and plowing, thereby reducing the coefficient of friction and wear rate. However, excessively high Mo2BC nanoparticle content can easily lead to agglomeration and the formation of brittle particle clusters, which in turn reduces the alloy's toughness, plasticity, and wear resistance. Therefore, this invention strictly controls the Mo2BC content within the range of 0.20% to 0.40%.

[0035] (10) The addition of SiC nanofibers is the key strengthening and toughening method of this invention. Its one-dimensional morphological characteristics and interface regulation synergistic strengthening mechanism play a key role in improving the strength, toughness and wear resistance of copper alloys. In terms of strength and toughness, SiC nanofibers are dispersed in the Cu matrix and form a strong heterogeneous interface with the matrix. When subjected to external force, due to the high strength of SiC itself, the interfacial shear stress can be effectively transferred to the high-hardness fiber body through the matrix. At the same time, the fiber can play a bridging role in the crack propagation process, forming traction force between crack surfaces, consuming crack propagation energy, and inducing multiple energy consumption mechanisms such as fiber pull-out, crack deflection and fiber breakage, thereby simultaneously achieving a synergistic improvement in strength and toughness. In terms of wear resistance, the contribution of SiC nanofibers comes from its anisotropic structure and interface-induced strengthening mechanism. Fibers oriented perpendicular to the sliding interface can form a wear-resistant skeleton. Simultaneously, the surface fibers undergo micro-fracture during continuous friction and mechanically mix with wear debris and matrix materials to form a dense reinforcing layer, blocking metal-to-metal contact between the wear pairs and enhancing the alloy's wear resistance. However, excessively high SiC nanofiber content can easily lead to fiber agglomeration, promote interfacial debonding, and induce micropore aggregation fracture, weakening the alloy's resistance to fatigue spalling. Therefore, this invention strictly controls the SiC content within the range of 0.050% to 0.100%.

[0036] (11) Pb and Sn have a significant detrimental effect on the elasticity and wear resistance of beryllium copper alloys. Pb is almost insoluble in the Cu matrix and is distributed in the form of free soft particles at grain boundaries and within grains. Under stress, it is easy to debond from the matrix to form micropores, which significantly reduces the strength of the alloy. During friction, it is squeezed out and peeled off, transforming into abrasive particles that aggravate wear. Sn, on the other hand, agglomerates at grain boundaries, weakening the interfacial bonding force and inducing intergranular brittle fracture and delamination wear. More fatally, the two can form a low-melting-point eutectic phase at the grain boundary, which undergoes instantaneous liquefaction under friction flash temperature, resulting in a sharp drop in grain boundary strength, grain slippage and rotation, and seepage to the surface to form thermal tearing pits. When the content of Pb and Sn is too high, the low-melting-point eutectic network will penetrate the grain boundary, making the material exhibit hot brittleness and the wear rate will rise sharply. Therefore, this invention strictly limits their content, requiring Pb ≤ 0.005% and Sn ≤ 0.005%.

[0037] (12) In order to ensure the stability and consistency of the microstructure and overall properties of the alloy of the present invention, the total amount of other unavoidable impurity elements should be strictly controlled to ≤0.01%.

[0038] The present invention discloses a method for preparing a high-strength, high-wear-resistant beryllium copper alloy for switches, comprising metallization treatment, batching, special smelting, homogenization treatment, milling, hot rolling, annealing, solution treatment, pickling, cold rolling, pickling and passivation, and aging treatment, specifically including the following steps: (1) Metallization treatment Ti(C,N) nanoparticles with a particle size of 30nm–50nm, Mo2BC nanoparticles with a particle size of 50nm–100nm, and SiC nanofibers with a diameter of 200nm–500nm and an aspect ratio of 10–20 were selected as raw materials and subjected to electroless copper plating. First, the nanoparticles were ultrasonically cleaned in a 10wt% NaOH solution to remove oil, and then roughened in a 25% vol HNO3 solution for 10 min to improve surface activity. Subsequently, the nanoparticles were sensitized by immersion in a SnCl2-HCl solution with a mass ratio of 1:1.2 for 10 min to allow the surface to adsorb reduced Sn. 2 + The powder was then transferred to a palladium chloride (1 g / L) activation solution, and the pH of the solution was adjusted to 2 with hydrochloric acid. The mixture was stirred at room temperature for 8 minutes. Finally, the activated powder was immersed in a 60°C electroless copper plating solution for 30 minutes. The solution composition was CuSO4·5H2O 25 g / L, potassium sodium tartrate 85 g / L, formaldehyde 11 mL / L, and 2,2'-bipyridine 80 ppm. The pH of the solution was adjusted to 12 with NaOH. During the plating process, mechanical stirring and intermittent ultrasonication were used to ensure a continuous and uniform coating. After plating, the powder was sequentially cleaned, passivated with BTA solution (benzotriazole, concentration 2 g / L), and vacuum dried to obtain three types of powder with well-coated copper.

[0039] (2) Ingredients Oxygen-free copper, Cu-25%Be master alloy, electrolytic cobalt, electrolytic nickel, electrolytic chromium, Cu-18%Si master alloy, Mg-30%Cu master alloy, Cu-20%Y master alloy, and metal-treated reinforcing powder were selected as raw materials. Among these, Be, Si, Mg, and Y elements are highly reactive; using master alloys instead of pure metals significantly reduces burn-off during smelting. Subsequently, the raw materials were sandblasted to remove surface impurities and rust, then degreased, cleaned, and dried before use. The raw materials were formulated according to the mass percentages of the chemical composition described in this invention.

[0040] (3) Smelting The prepared alloy raw materials are placed in a vacuum induction furnace and melted at a temperature of 1220℃~1250℃ until the alloy raw materials are completely melted. The temperature is then increased to 1450℃~1480℃ for refining, and the refining time is controlled at 15min~20min. Then, the metal-treated reinforcing powder is added to the alloy liquid through a secondary feeding device. At the same time, a preheated vibrating amplitude rod is inserted into the alloy melt for ultrasonic treatment to make the nano powder uniformly dispersed in the alloy liquid. The amplitude rod is made of zirconia toughened alumina (ZTA) material, the vibration frequency is 30kHz, and the treatment time is 10min. Then, the temperature is reduced to 1120℃~1150℃, the amplitude rod is quickly pulled out, and the alloy liquid is poured into a water-cooled mold to obtain a beryllium copper alloy billet.

[0041] (4) Homogenization treatment The beryllium copper alloy billet is placed in the homogenization zone of a heat treatment furnace for homogenization treatment. The temperature is raised to 850℃~880℃ and held for 20h~30h. Then the billet is placed in a quenching solution for forced cooling. After the billet temperature drops to room temperature, it is taken out for use.

[0042] (5) Milling After homogenization, the billet is milled to remove oxide scale and defects from its surface, resulting in a clean and dimensionally accurate billet for rolling, thus ensuring quality for subsequent rolling operations.

[0043] (6) Hot rolling The billet is placed in a heating furnace at 900±20℃ and held for 40 to 80 minutes to ensure that both the inside and outside of the billet reach the set temperature. It is then removed from the furnace and hot-rolled. The roughing temperature is 880℃ to 900℃, the finishing temperature is 750℃ to 780℃, and the total hot rolling rate is 90% to 95%. It is then cooled to room temperature in air.

[0044] (7) Annealing treatment The hot-rolled copper plate is placed in the homogenization zone of the heat treatment furnace for annealing. The temperature is raised to 800℃~820℃ and held for 4h~8h. Then the copper plate is air-cooled to room temperature.

[0045] (8) Solution treatment After annealing, the copper plate is placed in the homogenization zone of the heat treatment furnace for solution treatment. The temperature is raised to 880℃~900℃ and held for 1h~2h. The copper plate is then placed in the quenching solution for forced cooling. After the copper plate temperature drops to room temperature, it is taken out for use.

[0046] (9) Pickling After solution treatment, the copper plate was placed in a 2% sodium carbonate cleaning solution for degreasing and cleaning at a temperature of 65°C. Subsequently, it was immersed in a 2.5% dilute sulfuric acid solution for 10 minutes, followed by cleaning to remove the oxide scale. Finally, the copper plate surface was thoroughly cleaned with an ethanol-water solution.

[0047] (10) Cold rolling The pickled copper plates are cold-rolled using a two-stage cold rolling process followed by intermediate annealing. The first cold rolling stage achieves a total processing yield of 80%–90%, with an annealing temperature of 320℃–350℃ and a holding time of 2–4 hours. The second cold rolling stage achieves a total processing yield of 45%–65%, with an annealing temperature of 400℃–420℃ and a holding time of 6–8 hours.

[0048] (11) Pickling and passivation The cold-rolled copper strip undergoes pickling and passivation treatment. First, the copper strip is placed in a 2% sodium carbonate cleaning solution for degreasing and cleaning at 65℃. Then, it is immersed in a 2.5% dilute sulfuric acid solution for 10 minutes, followed by cleaning of the copper strip surface. Finally, passivation treatment is performed by spraying a 0.2% BTA aqueous solution onto the copper strip surface, allowing the Cu... + After the reaction with BTA molecules is complete, a surface passivation layer is obtained. The copper strip surface is then cleaned and dried for later use.

[0049] (12) Timeliness processing The passivated copper strip is placed in the homogenization zone of a heat treatment furnace for aging treatment, which adopts a two-stage aging process. The first-stage aging temperature is 320℃~340℃, and the holding time is 2h~4h. The second-stage aging temperature is 380℃~400℃, and the holding time is 6h~8h. The copper strip is then air-cooled to room temperature to obtain the finished copper strip.

[0050] This invention measures the tensile properties of beryllium copper alloys using an electronic universal testing machine, based on the national standard GB / T 34505-2017 "Tension Test Method for Copper and Copper Alloys at Room Temperature".

[0051] This invention measures the Rockwell hardness of beryllium copper alloys using a Rockwell hardness tester, based on the national standard GB / T 230.1-2018 "Metallic materials - Rockwell hardness test - Part 1: Test method".

[0052] This invention measures the wear rate of beryllium copper alloy using a metal friction and wear testing machine, based on the national standard GB / T 12444-2006 "Metallic Materials Wear Test Method - Test Ring-Block Sliding Wear Test".

[0053] Example 1: Refer to Figure 1 A method for preparing a high-strength, high-wear-resistant beryllium copper alloy for switches includes the following steps: Step 1: Metallization pretreatment of the reinforcing phase. Ti(C,N) nanoparticles with a particle size of 30nm-50nm, Mo2BC nanoparticles with a particle size of 50nm-100nm, and SiC nanofibers with a diameter of 200nm-500nm and an aspect ratio of 10-20 were selected and subjected to electroless copper plating. The specific process includes: alkaline washing to remove oil, acid washing to roughen, SnCl2-HCl solution sensitization, palladium chloride solution activation, and then plating in a plating solution with the composition of CuSO4·5H2O 25g / L, potassium sodium tartrate 85g / L, formaldehyde 11mL / L, 2,2'-bipyridine 80ppm, and pH=12 for 30min, supplemented by mechanical stirring and intermittent ultrasonication. After plating, the powder was cleaned, passivated, and dried to obtain copper-coated metallized reinforcing powder.

[0054] Step 2: Batching. The alloy chemical composition, by weight percentage, is: Be: 1.81%, Co: 1.53%, Ni: 1.03%, Si: 0.06%, Cr: 0.05%, Mg: 0.062%, Y: 0.163%, Ti(C,N): 0.31%, Mo2BC: 0.20%, SiC: 0.052%, Pb: 0.004%, Sn: 0.005%, with other unavoidable impurities ≤0.01%, and the balance being Cu. Oxygen-free copper, Cu-25%Be master alloy, electrolytic cobalt, electrolytic nickel, electrolytic chromium, Cu-18%Si master alloy, Mg-30%Cu master alloy, Cu-20%Y master alloy, and the aforementioned metallized reinforcing powders are selected as raw materials. The raw materials are sandblasted and degreased before being weighed according to the specified proportions.

[0055] Step 3: Melting and Ultrasonic Dispersion. The alloy raw material is placed in a vacuum induction furnace and melted completely at 1220℃. The temperature is then raised to 1450℃ for a first refining process of 15 minutes. Subsequently, metallized reinforcing powder is added for a second feeding, and a vibrating amplitude transformer is inserted into the melt for ultrasonic treatment at a vibration frequency of 30kHz for 10 minutes to ensure uniform dispersion of the reinforcing powder. Finally, the temperature is lowered to 1120℃ and cast into a water-cooled mold to obtain a beryllium copper alloy billet.

[0056] Step 4: Homogenization treatment, after holding the billet at 850℃ for 20 hours, quench it to room temperature.

[0057] Step 5: Hot rolling. After holding the billet in a heating furnace at 880℃ for 40 minutes, hot rolling is carried out. The roughing temperature is 880℃, the finishing temperature is 750℃, the total hot rolling rate is 90%, and then air-cooled to room temperature.

[0058] Step 6: Annealing and solution treatment. The hot-rolled plate is annealed at 800℃ for 4 hours and then air-cooled, followed by solution treatment at 880℃ for 1 hour and forced cooling.

[0059] Step 7: Cold rolling. The pickled sheet is subjected to two cold rolling processes and intermediate annealing. The total processing rate of the first cold rolling is 80%, followed by annealing at 320℃ for 2 hours; the total processing rate of the second cold rolling is 45%, followed by annealing at 400℃ for 6 hours.

[0060] Step 8: Pickling and passivation. After degreasing and pickling, the cold-rolled copper strip is sprayed with a 0.2% benzotriazole (BTA) aqueous solution for passivation treatment, and then cleaned and dried.

[0061] Step 9: Aging treatment. The passivated copper strip is subjected to a two-stage aging treatment. The first-stage aging temperature is 320℃ and held for 2 hours, and the second-stage aging temperature is 380℃ and held for 6 hours. It is then air-cooled to room temperature to obtain the finished copper strip.

[0062] The beryllium copper alloy strip prepared in this embodiment has a thickness of 0.5 mm to 2.0 mm. Testing showed a yield strength of 1204 MPa, a tensile strength of 1393 MPa, an elongation after fracture of 3.88%, a Rockwell hardness of HRC 52, and a wear rate of 1.35 × 10⁻⁶. -4 mm 3 / (N·m).

[0063] The methods and steps in Examples 2-8 are the same as those in Example 1, and the specific parameters are shown in Tables 1-6.

[0064] Comparative Example 1 QBe1.9: This comparative example was prepared using the existing grade QBe1.9 beryllium copper alloy, with the following chemical composition: Be: 2.02%, Ni: 0.35%, Si: 0.02%, Al: 0.06%, Ti: 0.22%, Fe: 0.04%, Pb: 0.004%, and the total amount of other unavoidable impurity elements ≤0.10%, with the balance being Cu.

[0065] The preparation method includes the following steps: Step 1: Ingredient preparation. Weigh the raw materials according to the above chemical composition and use conventional beryllium copper alloy raw materials for preparation.

[0066] Step 2: Melting and casting. The raw material is placed in a vacuum induction furnace and melted at 1200℃ until completely melted. Then, the temperature is raised to 1350℃ for a refining process for 10 minutes. Finally, it is cast into a water-cooled mold at 1130℃ to obtain a beryllium copper alloy billet.

[0067] Step 3: Homogenization treatment. Place the billet in the homogenization zone of the heat treatment furnace, heat it to 750℃ and hold it for 8 hours, then quench it to room temperature.

[0068] Step 4: Hot rolling. The billet is held in a heating furnace at 850℃ for 30 minutes, and then hot rolled at 820℃ for roughing and 700℃ for finishing. The total hot rolling rate is 80%, and the billet is air-cooled to room temperature.

[0069] Step 5: Annealing and solution treatment. The hot-rolled plate is annealed at 500℃ for 4 hours and then air-cooled. Then it is solution treated at 850℃ for 2 hours and then quenched.

[0070] Step 6: Cold rolling. After pickling to remove oxide scale, the product undergoes two cold rolling processes. The first cold rolling process yields a total processing rate of 75%, followed by annealing at 300℃ for 1 hour. The second cold rolling process yields a total processing rate of 45%, followed by annealing at 380℃ for 4 hours.

[0071] Step 7: Aging treatment. The cold-rolled copper strip is aged at 310℃ for 3 hours and then air-cooled to room temperature to obtain the finished copper strip.

[0072] The beryllium copper alloy strip prepared in this comparative example was tested and found to have a yield strength of 1158 MPa, a tensile strength of 1325 MPa, an elongation after fracture of 3.92%, a Rockwell hardness of HRC 45, and a wear rate of 2.44 × 10⁻⁶. -4 mm 3 / (N·m).

[0073] The procedure for comparative example C17200 is the same as that for comparative example 1QBe1.9. Specific parameters are shown in Tables 1-6.

[0074] Table 1. Chemical composition and content (wt%) of beryllium copper alloy in the embodiments of the present invention.

[0075] Table 2 Smelting process parameters of beryllium copper alloy in the embodiments of the present invention

[0076] Table 3 Hot rolling process parameters of beryllium copper alloy in the embodiments of the present invention

[0077] Table 4 Cold rolling process parameters of beryllium copper alloy in the embodiments of the present invention

[0078] Table 5 Heat treatment process parameters of beryllium copper alloy in the embodiments of the present invention

[0079] Table 6 Mechanical properties of beryllium copper alloys in the embodiments of the present invention

[0080] Referring to Table 6, this invention employs a matrix design of "high Be (1.80%~2.20%) + Ni, Co synergistic reinforcement," combined with a two-stage aging process, achieving a yield strength of 1204 MPa and a tensile strength of 1393 MPa, which are improvements over the traditional QBe1.9 alloy. The Rockwell hardness also jumps from 45 HRC to 52 HRC. This enhanced matrix strength provides strong support against plastic deformation and micro-cutting during friction. Furthermore, by introducing Ti(C,N), Mo2BC nanoparticles and SiC nanofibers treated with electroless copper plating, and supplementing the melting process with ultrasonic dispersion, uniform distribution of the nano-reinforcing phases in the copper matrix is ​​achieved. These high-hardness reinforcing phases act as a load-bearing skeleton, effectively suppressing abrasive indentation and ploughing, reducing the wear rate from 2.44 × 10⁻⁶. -4 mm 3 / N·m decreased to 1.35×10 -4 mm 3 / N·m, wear resistance is improved. While the strength and hardness are significantly improved, the elongation after fracture is still maintained, indicating that the present invention significantly strengthens the alloy without sacrificing plasticity, thus ensuring the comprehensive service performance of the material under dynamic working conditions.

[0081] The above provides a detailed description of a high-strength, high-wear-resistant beryllium copper alloy for switches and its preparation method. Specific examples have been used to illustrate the structure and working principle of the invention. The descriptions of these embodiments are merely for the purpose of helping to understand the method and core ideas of the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A high-strength, high-wear-resistant beryllium copper alloy for switches, characterized in that: The chemical composition by weight percentage includes: Be: 1.80%–2.20%, Co: 1.50%–2.00%, Ni: 1.00%–1.60%, Si: 0.05%–0.10%, Cr: 0.05%–0.20%, Mg: 0.060%–0.080%, Y: 0.160%–0.220%, Ti(C,N): 0.30%–0.50%, Mo2BC: 0.20%–0.40%, SiC: 0.050%–0.100%, Pb≤0.005%, Sn≤0.005%, other unavoidable impurity elements ≤0.01%, and the balance being Cu.

2. The high-strength, high-wear-resistant beryllium copper alloy for switches according to claim 1, characterized in that: The beryllium copper alloy is processed into a thin strip with high strength and high wear resistance for switches, and the thickness of the thin strip is 0.5mm to 2.0mm.

3. The high-strength, high-wear-resistant beryllium copper alloy for switches according to claim 2, characterized in that: The strip material meets the following performance indicators: yield strength > 1200 MPa, tensile strength > 1390 MPa, elongation > 3%, Rockwell hardness HRC > 50, and wear rate < 1.5 × 10⁻⁶. -4 mm 3 / N·m.

4. The high-strength, high-wear-resistant beryllium copper alloy for switches according to claim 1, characterized in that: The raw materials for the chemical composition are as follows: oxygen-free copper, Cu-25%Be master alloy, electrolytic cobalt, electrolytic nickel, electrolytic chromium, Cu-18%Si master alloy, Mg-30%Cu master alloy, Cu-20%Y master alloy, and Ti(C,N), Mo2BC, and SiC are respectively selected from Ti(C,N) nanoparticles with a particle size of 30nm to 50nm, Mo2BC nanoparticles with a particle size of 50nm to 100nm, and SiC nanofibers with a diameter of 200nm to 500nm and an aspect ratio of 10 to 20.

5. A method for preparing the high-strength, high-wear-resistant beryllium copper alloy for switches according to any one of claims 1 to 4, characterized in that: Includes the following steps, Step 1: Metallization pretreatment of the reinforcing phase. Ti(C,N) nanoparticles, Mo2BC nanoparticles and SiC nanofibers are chemically plated with copper to form a copper coating layer on the particle surface, thus obtaining metallized reinforced powder. The chemical copper plating process includes the following steps: the particles are sequentially subjected to alkaline washing to remove oil, acid washing to roughen, SnCl2-HCl solution sensitization, and palladium chloride solution activation. Then, they are plated in the chemical copper plating solution. During the plating process, mechanical stirring and intermittent ultrasonication are used. The composition of the plating solution is CuSO4·5H2O, potassium sodium tartrate, formaldehyde, and 2,2'-bipyridine. The pH of the solution is adjusted with NaOH. Step 2: Batching. Weigh the alloy raw materials and the metallized reinforcing powder obtained in Step 1 according to the required alloy chemical composition by weight percentage. Step 3: Melting and Ultrasonic Dispersion: The alloy raw materials are placed in a vacuum induction furnace for melting and refining. The melting is carried out at 1220℃~1250℃ until completely melted. The temperature is then raised to 1450℃~1480℃ for a first refining for 15min~20min. Subsequently, metallized reinforcing powder is added to achieve secondary feeding. A vibrating amplitude transformer is inserted into the melt for ultrasonic treatment. The vibration frequency of the ultrasonic treatment is 30kHz and the treatment time is 10min to uniformly disperse the reinforcing powder. Finally, the temperature is lowered to 1120℃~1150℃ and water-cooled for casting to obtain a beryllium copper alloy billet. Step 4: Thermomechanical processing and heat treatment. The billet from Step 3 is subjected to homogenization treatment, hot rolling, annealing, solution treatment, cold rolling, and aging treatment in sequence to obtain beryllium copper alloy strip.

6. The method for preparing a high-strength, high-wear-resistant beryllium copper alloy for switches according to claim 5, characterized in that: The homogenization treatment in step 4 is carried out at a temperature of 850℃~880℃ for 20h~30h.

7. The method for preparing a high-strength, high-wear-resistant beryllium copper alloy for switches according to claim 5, characterized in that: The total processing rate of hot rolling in step 4 is 90% to 95%, wherein the rough rolling temperature is 880℃ to 900℃ and the finish rolling temperature is 750℃ to 780℃.

8. The method for preparing a high-strength, high-wear-resistant beryllium copper alloy for switches according to claim 5, characterized in that: The annealing process in step 4 involves holding the hot-rolled plate at 800℃~820℃ for 4h~8h and then air-cooling it to obtain an annealed plate; the solution treatment involves holding the annealed plate at 880℃~900℃ for 1h~2h and then forcibly cooling it.

9. The method for preparing a high-strength, high-wear-resistant beryllium copper alloy for switches according to claim 5, characterized in that: Step 4 cold rolling includes two cold rolling processes and intermediate annealing. The total processing rate of the first cold rolling is 80% to 90%, the intermediate annealing temperature is 320℃ to 350℃, and the holding time is 2h to 4h. The total processing rate of the second cold rolling is 45% to 65%, the intermediate annealing temperature is 400℃ to 420℃, and the holding time is 6h to 8h.

10. The method for preparing a high-strength, high-wear-resistant beryllium copper alloy for switches according to claim 5, characterized in that: The aging treatment described in step 4 is a two-stage aging treatment. The first-stage aging temperature is 320℃~340℃, and the holding time is 2h~4h. The second-stage aging temperature is 380℃~400℃, and the holding time is 6h~8h.

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