High-strength high-elasticity Cu-Ni-Mn-V alloy and preparation method thereof

Abstract

The application discloses a high-strength and high-elasticity Cu-Ni-Mn-V alloy and a preparation method thereof. The main components of the alloy are as follows in percentage by mass: Ni, 18-22%; Mn, 18-22%; V, 0.1-1.0%; and the balance is copper and inevitable impurities. The application adds the alloy element V, controls the Ni / Mn ratio to be 0.8-1.2, matches the appropriate deformation and heat treatment process, makes the NiMn strengthening phase precipitate, improves the distribution of the aging precipitation phase of the alloy, forms the intermetallic compound Ni3V with V and Ni, suppresses the precipitation of the discontinuous precipitation phase (DP), refines the alloy grains, and obtains the high-strength and high-elasticity Cu-Ni-Mn-V alloy with the tensile strength greater than or equal to 1400 MPa, the elongation greater than or equal to 6%, and the elastic modulus greater than or equal to 130 GPa. The Cu-Ni-Mn-V alloy prepared by the application has the uniform and small structure, high strength, and excellent comprehensive performance of good elasticity and plasticity.

Description

TECHNICAL FIELD

[0001] The application relates to a high-strength and high-elasticity Cu-Ni-Mn-V alloy and a preparation method thereof, and belongs to the technical field of multi-element Cu alloy materials. BACKGROUND

[0002] High-strength and high-elasticity copper alloy generally refers to a copper alloy with a strength of more than 1000 MPa and an elastic modulus of more than 125 GPa; the high-strength and high-elasticity copper alloy is widely applied in fields of sensors, spring tubes, high-reliability connectors, temperature controllers, relays, instruments, automobile parts, electronic appliances, aerospace and marine engineering, etc. due to its high strength, high elasticity, high working temperature, good stress corrosion resistance, good electrical conductivity and thermal conductivity, non-magnetic property and non-toxicity.

[0003] At present, the most widely used high-strength and high-elasticity copper alloy is a Cu-Be alloy, the Cu-Be alloy contains beryllium which is a highly toxic substance, and the stress relaxation rate of the Cu-Be alloy sharply increases at a temperature higher than 150 DEG C, so that the contact pressure of an elastic component in a working state is easily changed, and the working failure of a connector is caused; it is urgent to develop a new type of environmentally-friendly super-high-strength, high-stress relaxation resistance, excellent forming performance and high-reliability conductive elastic copper alloy; the Cu-Ni-Mn-V alloy has good mechanical properties, excellent corrosion resistance and excellent stress relaxation resistance at high temperatures, but the elongation of the Cu-Ni-Mn-V alloy is relatively poor, the alloy disclosed in the application adds vanadium to form intermetallic compounds with nickel, and the alloy grains are refined, so that the strength and plasticity of the alloy are further improved. SUMMARY

[0004] The application aims to provide a high-strength and high-elasticity Cu-Ni-Mn-V alloy, the Cu-Ni-Mn-V alloy comprises Ni: 18-22 wt%, Mn: 18-22 wt%, V: 0.1-1.0 wt%, and the balance is copper, the sum of the mass percentages of the components is 100%; after deformation and heat treatment, the tensile strength of the alloy is greater than or equal to 1400 MPa, the elongation is greater than or equal to 6%, and the elastic modulus is greater than or equal to 130 GPa, so that the alloy can be widely applied in fields of aerospace, marine engineering, medical devices, electronic appliances, automobile parts, etc., and also provides important guiding significance for subsequent engineering application and scientific research.

[0005] Another object of the present application is to provide a preparation method of the high-strength and high-elasticity Cu-Ni-Mn-V alloy, by adding V element, forming a second phase distributed at the grain boundary to occupy the nucleation position of discontinuous precipitated phase or distributed in the matrix to hinder the migration of the grain boundary, inhibiting the precipitation of discontinuous precipitated phase, refining the grain, controlling the Ni / Mn ratio to be 0.8-1.2, precipitating NiMn strengthening phase during aging, improving the strength of the alloy, and obtaining the high-strength and high-elasticity Cu-Ni-Mn-V alloy, which specifically comprises the following steps:

[0006] (1) Billet melting and casting: copper, nickel, manganese and vanadium are weighed according to the mass percentage, melted in a vacuum induction furnace under the protection of argon, and poured into a square alloy ingot in a graphite mold.

[0007] (2) Homogenization: the alloy billet is subjected to homogenization treatment to make the diffusion of Ni and Mn in Cu more uniform, and after milling to remove surface impurities and oxide layers, subsequent deformation treatment is performed.

[0008] (3) Deformation process: the alloy billet is subjected to hot rolling deformation with a total deformation of 70-80%; after hot rolling, cold rolling deformation with a total deformation of 70-90% is performed. After uniformizing the ingot structure, homogenization treatment is performed, and then hot rolling is performed, which can reduce deformation cracking caused by uneven composition, and hot rolling can also break up the coarse grains in the alloy; further breaking up the grains of the alloy through large deformation cold rolling forms a fibrous deformation structure, improves the alloy performance, and shortens the aging incubation period.

[0009] (4) Solid solution treatment: the cold-rolled alloy plate is heated to 600-750℃, and held for 1-2h, and then water quenched.

[0010] (5) Aging treatment: the alloy plate after solid solution treatment is heated to 350-450℃, held for 8-16h, and air cooled to room temperature; after solid solution treatment, aging treatment can make the alloy precipitate a large amount of nanoscale NiMn strengthening phase and Ni3V strengthening phase, and the strength of the alloy is doubled, from about 700 MPa to about 1400 MPa after aging.

[0011] Preferably, the content of Ni and Mn solute atoms in the present application is greater than 10 wt.%, and the ratio of Ni and Mn solute atoms is 0.8-1.2.

[0012] Preferably, when melting, the pressure of the argon filled should be greater than the equilibrium vapor pressure of manganese 0.13x10 3 Pa, to prevent the volatilization of manganese element.

[0013] Preferably, in step (1) of the present invention, the melting temperature is higher than 1250℃, and the temperature is kept at 1200-1300℃ for 15-20 minutes before casting, so as to ensure that the solute atoms are fully dissolved and diffused evenly.

[0014] Preferably, the homogenization treatment temperature in step (2) of the present invention is 900-950℃, the holding time is 4-8h, and slow cooling with the furnace is adopted to obtain an alloy ingot with uniform solute element distribution.

[0015] Preferably, in step (3) of the present invention, the alloy billet is heated to 850-900°C and held for 20 minutes, and then hot-rolled at this temperature for 8-12 passes of hot rolling deformation; and cold-rolled at room temperature for 10-15 passes of cold rolling deformation.

[0016] Based on the phase diagram and strengthening mechanism of Cu-Ni-Mn alloys, this invention improves the size and distribution of aging precipitates in Cu-Ni-Mn alloys and suppresses the precipitation of discontinuous precipitates by adding microalloying element V and matching appropriate heat treatment processes, controlling the content of Ni and Mn solute atoms to be greater than 10 wt.% and the ratio of Ni to Mn solute atoms to be approximately 1:1. This results in a high-strength and high-elasticity copper alloy with superior performance, which can then replace beryllium copper.

[0017] Advantages of this invention:

[0018] (1) By adding V element, the mixing enthalpy of Ni and V is −18 kJ / mol. The mixing enthalpy is negative, indicating that the atoms are compatible and can easily combine to form Ni3V intermetallic compounds. These compounds are distributed at the grain boundaries to occupy the nucleation sites of discontinuous precipitates or distributed in the matrix to hinder the migration of grain boundaries, suppress the precipitation of discontinuous precipitates, and refine the grains. By controlling the Ni / Mn ratio to be about 1, NiMn strengthening phases are precipitated during aging, which improves the strength of the alloy and obtains a high-strength and high-elasticity Cu-Ni-Mn-V alloy.

[0019] (2) By designing the alloy composition and micro-alloying and matching it with appropriate deformation and heat treatment processes, the microstructure, grain size and distribution of precipitates of the alloy can be further controlled, the aging incubation period can be shortened, the aging cycle can be reduced, and the overall performance of the alloy can be improved.

[0020] (3) The high-strength and high-elasticity Cu-Ni-Mn-V alloy involved in this invention has a simple preparation process, a short process flow, does not contain any elements that are harmful to the human body and the environment, and has excellent comprehensive performance. It is an excellent substitute for traditional elastic alloys such as beryllium bronze.

[0021] Based on the inherent high strength and elastic modulus and low cost of Cu-Ni-Mn alloy, this invention further improves its mechanical properties by microalloying to control the microstructure and precipitates, and significantly shortens its aging time, reducing the difficulty of its heat treatment process. The process is simple and has obvious technical advantages. Attached Figure Description

[0022] Figure 1 This is a process flow diagram for preparing the ultra-high strength and high elasticity Cu-Ni-Mn-V alloy of the present invention.

[0023] Figure 2 These are microstructure diagrams of the as-cast Cu-Ni-Mn-V alloys in Examples 1-3;

[0024] Figure 3 These are microstructure diagrams of the Cu-Ni-Mn-V alloys after solution treatment in Examples 1 and 3;

[0025] Figure 4 This is the engineering stress-strain curve of the Cu-Ni-Mn-V alloy in Example 3. Detailed Implementation

[0026] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, and the raw materials mentioned can be obtained commercially.

[0027] A method for preparing a high-strength, high-elasticity Cu-Ni-Mn-V alloy, specifically including the following steps:

[0028] (1) Billet casting: Weigh copper, nickel, manganese, and vanadium according to the mass percentages in Table 1, wherein the content of Ni and Mn solute atoms is greater than 10 wt.% and the ratio of Ni to Mn solute atoms is 1. Melt under the protection of argon in a vacuum induction melting furnace. During melting, the pressure of the argon gas should be greater than the equilibrium vapor pressure of manganese by 0.13 × 10⁻⁶. 3 Pa prevents the volatilization of manganese; the melting temperature is above 1250℃ and held at 1200℃ for 15 minutes, and then cast into a square alloy ingot in a graphite mold.

[0029] (2) Homogenization: The alloy billet is homogenized at a temperature of 900℃ and a holding time of 8h to make the diffusion of Ni and Mn in Cu more uniform. Slow cooling in the furnace is adopted, and the surface impurities and oxide layer are removed by milling before subsequent deformation treatment.

[0030] (3) Deformation process: the alloy blank is heated to 850℃ and kept for 20 min, then hot rolling is carried out at the temperature to deform 8 passes, and the total deformation is 70%; after hot rolling, cold rolling is carried out at room temperature to deform 10 passes, and the total deformation is 70%.

[0031] (4) Solution treatment: the alloy plate after cold rolling is heated to 600℃, kept for 2 h, and water quenched.

[0032] (5) Aging treatment: the alloy plate after solution treatment is heated to 450℃, kept for 16 h, and air cooled to room temperature to obtain the Cu-Ni-Mn-V alloy, and the mechanical properties are shown in Table 2.

[0033] Table 1 Content of alloying elements in examples

[0034]

[0035] Table 2 Mechanical properties of alloys in examples

[0036]

[0037] As can be seen from Table 2, compared with Examples 1-3 and Comparative Example 1, it can be seen that the addition of V can significantly improve the strength and elongation of the alloy. By adding V element, the intermediate compound Ni3V is distributed at the grain boundary to occupy the nucleation position of discontinuous precipitates or distributed in the matrix to hinder the migration of grain boundary, thereby inhibiting the precipitation of discontinuous precipitates and refining the grain.

[0038] By comparing Examples 2, 4 and 5, it can be seen that the higher the content of nickel and manganese, the higher the strength of the alloy, because more NiMn phase will precipitate, and NiMn phase has a large contribution to the strength of the alloy. Controlling the content of nickel and manganese to 20wt% is mainly considered from the cost, because the price of nickel is higher than that of copper. Example 6

[0039] A preparation method of a high-strength and high-elasticity Cu-20Ni-20Mn-0.6V alloy, specifically comprising the following steps:

[0040] (1) Blank casting: copper, nickel, manganese and vanadium are weighed according to the mass percentage of Cu-20Ni-20Mn-0.6V, wherein the content of Ni and Mn solute atoms is greater than 10wt.%, and the ratio of Ni and Mn solute atoms is 1. The melting is carried out in the protection of argon in a vacuum induction melting furnace, and the pressure of the filled argon should be greater than the equilibrium vapor pressure of manganese 0.13x10 3 Pa to prevent the volatilization of manganese element; the melting temperature is higher than 1250℃, and the temperature is kept at 1300℃ for 20 min, and then the square alloy ingot is cast in a graphite mold.

[0041] (2) homogenization: the alloy blank is subjected to homogenization treatment, the homogenization treatment temperature is 950℃, the holding time is 4h, the diffusion of Ni and Mn in Cu is more uniform, slow cooling in the furnace is adopted, after milling to remove surface impurities and oxide layer, subsequent deformation treatment is carried out.

[0042] (3) deformation process: the alloy blank is heated to 900℃ and held for 20min, then hot rolling is carried out at the temperature, 12 passes of hot rolling deformation are carried out, the total deformation is 80%; after hot rolling, 15 passes of cold rolling deformation are carried out at room temperature, the total deformation is 90%.

[0043] (4) solid solution treatment: the cold-rolled alloy plate is heated to 750℃, held for 1h, and water quenched.

[0044] (5) aging treatment: the alloy plate after solid solution treatment is heated to 350℃, held for 8h, and air cooled to room temperature, to obtain a Cu-Ni-Mn-V alloy, the mechanical properties are shown in Table 3.

[0045] Comparative Example 2

[0046] The conditions of this example and Example 6 are the same, except that only hot rolling is carried out without cold rolling, and the mechanical properties are shown in Table 3.

[0047] Comparative Example 3

[0048] The conditions of this example and Example 6 are the same, except that only cold rolling is carried out without hot rolling, and the mechanical properties are shown in Table 3.

[0049] Comparative Example 4

[0050] The conditions of this example and Example 6 are the same, except that no solid solution treatment is carried out, and the mechanical properties are shown in Table 3.

[0051] Comparative Example 5

[0052] The conditions of this example and Example 6 are the same, except that no aging treatment is carried out, and no hot rolling is carried out, and the mechanical properties are shown in Table 3.

[0053] Table 3 Mechanical properties of alloys in examples

[0054] Tensile strength (MPa) Elongation (%) Example 6 1545 3.8 Comparative Example 2 762.8 31 Comparative Example 3 1031 7.5 Comparative Example 4 1379 2.9 Comparative Example 5 589.3 38.2

[0055] As can be seen from Table 3, by comparing Example 6 and Comparative Example 2, it can be seen that cold rolling can greatly improve the strength of the alloy, cold rolling can further break the grains of the alloy, forming a fibrous deformation structure, and improving the performance of the alloy.

[0056] Compared with Example 6 and Comparative Example 3, it can be seen that the strength of the alloy without hot rolling is relatively low, and the hot rolling can reduce the composition unevenness and defects generated during casting, avoid cracking during deformation, and also can break the coarse grains in the alloy and cause dynamic recrystallization to improve the performance of the alloy.

[0057] Compared with Example 6 and Comparative Example 4, it can be seen that the alloy has poor elongation, and the alloy is not subjected to solid solution treatment, has large residual stress, high dislocation density, and difficult grain deformation, resulting in poor plasticity.

[0058] Compared with Example 6 and Comparative Example 5, it can be seen that the alloy without aging treatment has low strength and good plasticity, and the main strengthening mechanism of the alloy is aging precipitation strengthening, and a large amount of NiMn phase is precipitated from the matrix during aging process, and no strengthening phase is precipitated without aging treatment.

[0059] Figure 2 is a microstructure diagram of the as-cast Cu-Ni-Mn-V alloy in Examples 1-3, and it can be seen from the diagram that the as-cast structure of the Cu-Ni-Mn-V alloy is composed of columnar dendrites, which is due to the difficulty of diffusion of high content of alloying elements during solidification and slow cooling speed, thereby forming dendritic structure grains.

[0060] Figure 3 is a microstructure diagram of the Cu-Ni-Mn-V alloy after solid solution treatment in Examples 1 and 3, and it can be seen from the diagram that the broken grains after solid solution treatment of the alloy have recrystallization and grain growth, and the as-cast dendritic structure of the alloy is eliminated.

Claims

1. A high-strength, high-elasticity Cu-Ni-Mn-V alloy, characterized in that, The Cu-Ni-Mn-V alloy comprises Ni: 18-22wt%, Mn: 18-22wt%, V: 0.1-1.0wt%, with the balance being copper, and the sum of the mass percentages of each component is 100%. The content of Ni and Mn solute atoms is greater than 10 wt.%, and the ratio of Ni to Mn solute atoms is 0.8~1.2; The preparation method of the Cu-Ni-Mn-V alloy specifically includes the following steps: (1) Billet casting: Weigh copper, nickel, manganese and vanadium by mass percentage, melt them in a vacuum induction melting furnace under the protection of argon, and cast them into square alloy ingots in a graphite mold. (2) Homogenization: The alloy billet is homogenized to make the diffusion of Ni and Mn in Cu more uniform. After milling to remove surface impurities and oxide layer, subsequent deformation treatment is carried out. (3) Deformation process: hot rolling deformation of the alloy billet with a total deformation of 70-80%; cold rolling deformation of 70-90% after hot rolling. (4) Solution treatment: Heat the cold-rolled alloy plate to 600-750℃, hold for 1-2 hours, and then water quench; (5) Aging treatment: Heat the solution-treated alloy plate to 350-450℃, hold for 8-16 hours, and air cool to room temperature; During smelting, the pressure of the argon gas should be greater than the equilibrium vapor pressure of manganese by 0.13 × 10⁻⁶. 3 Pa, to prevent the volatilization of manganese; In step (1), the melting temperature is higher than 1250℃, and the temperature is held at 1200-1300℃ for 15-20 minutes before casting; In step (2), the homogenization treatment temperature is 900-950℃, the holding time is 4-8h, and slow cooling with the furnace is adopted to obtain an alloy ingot with uniform solute element distribution. The alloy billet described in step (3) is heated to 850-900℃ and held for 20 minutes. Then, it is hot rolled at this temperature and subjected to 8-12 passes of hot rolling deformation. After hot rolling, it is cold rolled for 10-15 passes at room temperature.

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