A method for producing a beryllium copper alloy

Abstract

The present application relates to a kind of preparation methods of beryllium copper alloy, comprising the following steps: (S1) according to mass accurately take raw material: copper, beryllium, copper yttrium alloy, copper titanium alloy, copper manganese alloy, nano ytterbium powder;(S2) the raw material is added to vacuum induction furnace, under inert atmosphere, temperature is raised to 1400-1600 ℃, after the raw material is all melted, on the molten material, smelting is spread under stirring condition, stationary, slagging, under the condition of 1100-1200 ℃, melt is poured in mould, and beryllium copper alloy ingot is obtained;(S3) beryllium copper alloy ingot is sequentially subjected to face milling treatment, solid solution treatment, cold working deformation treatment, aging treatment, and product beryllium copper alloy is obtained.The present application can significantly inhibit the occurrence of overaging by adding a small amount of metal elements and aging under microwave conditions, and then slowly cooling at a constant cooling rate, improve the hardness of alloy, and also improve the mechanical properties, especially the stress relaxation resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of copper alloy, and particularly relates to a preparation method of beryllium copper alloy. BACKGROUND

[0002] The beryllium copper alloy can be divided into high beryllium alloy (beryllium content 1.5-3%) and low beryllium alloy (beryllium content 0.2-1%) according to the content of beryllium metal. The beryllium copper alloy with high beryllium content has high strength, high hardness, high elasticity, high thermal conductivity, corrosion resistance, wear resistance, fatigue resistance and other excellent comprehensive properties, and plays an important role in many fields, especially in the fields of high technology such as instruments, electronics and aerospace. The beryllium copper alloy with high beryllium content has high strength and elasticity, and has excellent processability, easy casting, easy welding and easy electroplating characteristics, and is widely used in elastic sensitive and conductive devices, such as switch, reed, plug-in components and other elements in electronic instruments. However, due to the limitation of equipment and process, the performance of large-size beryllium copper alloy is inconsistent in the head, tail, surface and interior, especially the grain size is inconsistent, which leads to inconsistent performance, wide distribution of hardness and mechanical properties, and unstable performance. Beryllium exists in the alloy in the form of solid solution, but the current process of solid solution treatment is not sufficient, the phase transition is very fast, the grain is easy to grow during heating, there is a large volume change in the heat treatment process, and weak defects such as cracks and bubbles are formed, and local decomposition is easy to occur during solid solution process, which is very easy to cause overaging phenomenon, so that the grain size is widely dispersed after aging, and the mechanical properties cannot reach the same level of the same beryllium content alloy abroad.

[0003] CN112760521A discloses a preparation method of beryllium copper alloy, comprising the following steps: S1, taking copper raw material accounting for 85%-90% of the total mass of Cu for surface cleaning, and treating in dilute sulfuric acid to remove the oxide scale, putting the Cu treated by the peeling treatment into a vacuum melting furnace for melting treatment, when performing the vacuum melting treatment, the following method is adopted: vacuumizing to 0.005-0.010 Pa of the pressure in the furnace, then filling argon to 0.15-0.20 MPa, adding the Cu treated by the peeling treatment, Ni, Nb and Cr under the argon protection atmosphere, the feeding sequence is Cu, Ni, Cr and Nb, after the materials are completely melted, adding TiB2, Sn, Si and Zn, continuously melting until all the materials are melted, then keeping for 3-8 h, after the melting is completed, pouring to obtain a primary ingot; S2, forging the primary ingot obtained by step S1, when forging, the deformation amount is controlled to be 60-75%; S3, putting the primary ingot treated by step S2 into a vacuum melting furnace for melting treatment, controlling the melting conditions according to the operation mode of step S1 to perform secondary melting, adding the remaining copper raw material during the melting process, continuously melting until all the materials are melted, then closing the arc to cool the melt to complete solidification, turning over the solidified melt, repeating the melting, cooling and turning over steps for 3-4 times, after the melting is completed, pouring to obtain a secondary ingot; S4, forging the secondary ingot obtained by step S3, when forging, the deformation amount is controlled to be 80-90%, then performing solid solution quenching; S5, cold plastic processing the secondary ingot treated by step S4, controlling the single processing rate to be 60-70%, and obtaining a finished product in the material after the cold plastic processing is completed; S6, aging treatment of the finished product in the material after the cold plastic processing is completed, when treating, the aging temperature is controlled to be 350-380℃, after keeping for 3-8 h, air cooling or furnace cooling to obtain the finished product. The patent changes the traditional method of one-time large deformation and large plastic processing, adopts repeated melting and cooling operation to improve the uniformity of grain distribution, ensures that the alloy elements in the copper matrix will not be precipitated, avoids uneven grain size, and enhances the mechanical strength of fine grains. However, the patent needs multiple melting, which is time-consuming and laborious, and is not suitable for industrial large-scale production.

[0004] In the preparation of beryllium copper alloy, in order to improve the strength of the alloy, the material after solid solution and quenching treatment also needs to be aged. If the aging treatment is appropriate, it can give the alloy better elasticity, plasticity and fatigue resistance and other properties. The parameters of aging treatment are very important, and the temperature and time of aging treatment need to be reasonably controlled. However, due to the instability of heat treatment process, overaging phenomenon is easy to occur, that is, the grain boundary reaction is serious, which affects the performance of the alloy, which is an important problem that has not been fundamentally solved for domestic beryllium copper alloy. CN118006948A discloses a preparation method of high-strength high-conductivity high-plasticity beryllium copper alloy, wherein the aging treatment is carried out until the first strengthening peak of the alloy appears. The aging treatment has a first strengthening peak and a second strengthening peak, and the traditional aging treatment generally corresponds to the second strengthening peak. The patent aging treatment ends at the first strengthening peak, which improves the comprehensive performance of the alloy and shortens the aging treatment time. However, due to insufficient aging time, the strength and hardness performance is insufficient. CN102719699B discloses a preparation method of low beryllium copper alloy, adding cobalt, nickel, yttrium, or tin, cobalt and nickel can form a strengthening phase with beryllium, inhibit grain growth and improve alloy strength; yttrium can inhibit the discontinuous reaction of the alloy and improve the aging hardening effect of the alloy. The patent carries out two aging treatments, the first aging treatment temperature is 300-400℃ for 1-16h, and the second aging treatment temperature is 450-550℃ for 1-16h, and the second aging treatment temperature is 450-550℃ for 1-16h. However, the alloy obtained by the patent has insufficient stress relaxation and elastic modulus performance. SUMMARY

[0005] In order to solve the problems of the existing beryllium copper alloy preparation process, such as easy overaging and the need to improve the performance of the obtained alloy product, the present application provides a preparation method of beryllium copper alloy, which avoids overaging by adding specific metal elements and carrying out specific parameter microwave treatment during aging process. Specifically, the present application provides the following technical solutions to solve the above technical problems:

[0006] A preparation method of beryllium copper alloy, comprising the following steps:

[0007] (S1) accurately weighing the raw materials: copper, beryllium, copper-yttrium alloy, copper-titanium alloy, copper-manganese alloy, and nanometer ytterbium powder; the amount of raw materials satisfies that beryllium accounts for 1.8-2.6wt% of the raw materials, yttrium accounts for 0.3-0.5wt%, titanium accounts for 1.1-1.8wt%, manganese accounts for 0.2-0.4wt%, and ytterbium accounts for 0.12-0.17wt%;

[0008] (S2) adding the raw materials into a vacuum induction furnace, heating to 1400-1600℃ under inert atmosphere, making the raw materials melt completely, then sprinkling covering agent on the molten material, stirring under stirring condition, standing, skimming, pouring the melt into a mold at 1100-1200℃ to obtain beryllium copper alloy ingot;

[0009] (S3) The beryllium copper alloy ingot is sequentially subjected to face milling treatment, solid solution treatment, cold working deformation treatment and aging treatment to obtain the product beryllium copper alloy.

[0010] The prepared beryllium copper alloy of the present application adds yttrium, titanium, manganese and ytterbium in specific proportions, and the comprehensive performance of the product beryllium copper alloy is improved by the cooperation of each element. In particular, the addition of ytterbium endows the beryllium copper alloy with high yield strength and high stress relaxation resistance. However, the addition amount of ytterbium needs to be strictly controlled, and the alloy performance cannot be effectively improved when the addition amount is too much or too little.

[0011] Further, in step (S1), the purity of each raw material is ≥ 99.9%, and in particular, the content of phosphorus, arsenic and lead elements is ≤ 5ppm. Phosphorus impurities can promote abnormal grain growth of beryllium copper alloy, causing large grains, accelerating the decomposition of solid solution, and generating fusible substances distributed in the grain boundary, thereby reducing the strength of the alloy. Lead and arsenic impurities can promote grain boundary reaction of the alloy, accelerate aging softening, and are not conducive to the mechanical properties of the alloy.

[0012] Further, in step (S1), the yttrium content in the copper-yttrium alloy is 3-5wt%, the titanium content in the copper-titanium alloy is 6-10wt%, and the manganese content in the copper-manganese alloy is 6-10wt%.

[0013] Further, in step (S1), the particle size D90 of the nanometer ytterbium powder is 60-100nm.

[0014] Further, in step (S2), the inert atmosphere is argon, and the covering agent is at least one of graphite flake, borax and calcium fluoride. The melting is carried out under the stirring condition of a graphite stirring rod to uniformly mix the molten material, and the melting time is 3-5h.

[0015] Further, in step (S2), the covering agent is a compound mixture of graphite flake, borax and calcium fluoride in a mass ratio of 3-5:2-3:3-5. After the covering agent is ground and sieved, the particle size is 20-100μm.

[0016] Further, in step (S3), the face milling treatment is to mill off 1-2mm from the surface; the solid solution treatment temperature is 850-930℃, and the treatment time is 1-3h; the deformation amount of the cold working deformation treatment is ≥ 50-80%, such as 60%, 65%, 70% and 75%.

[0017] Further, in step (S3), the aging treatment is carried out under the condition of microwave with a power of 200-500W and a frequency of 600-1500MHz at 300-400℃ for 1-3h, and then slowly cooled at a cooling rate of 1-5℃ / min.

[0018] Further, the aging treatment is performed at 320-380 DEG C for 1-2 h under the microwave condition of 200-450 W power and 600-1000 MHz frequency, and then slowly cooled at a cooling rate of 1-4 DEG C / min.

[0019] In a preferred technical solution of the present application, the aging treatment is performed at 330-350 DEG C for 1-1.5 h under the microwave condition of 300-400 W power and 600-800 MHz frequency, and then slowly cooled at a cooling rate of 2-3 DEG C / min.

[0020] The beryllium copper alloy is sensitive to heat treatment process, especially the aging treatment, and over-aging phenomenon is very easy to occur, which causes serious grain boundary reaction and leads to the decrease of strength. The present application performs the aging treatment under the specific microwave condition, and then cools at the cooling rate, instead of the conventional air cooling, which can significantly inhibit the occurrence of over-aging phenomenon, increase the hardness of the alloy, and improve the mechanical properties, especially the stress relaxation resistance. DETAILED DESCRIPTION

[0021] The technical solutions of the present application are further explained and described below with specific examples.

[0022] The yttrium content in the copper-yttrium alloy used in the embodiment of the present application is 4.1 wt%, the titanium content in the copper-titanium alloy is 7.6 wt%, and the manganese content in the copper-manganese alloy is 8.2 wt%.

[0023] Example 1

[0024] (S1) The raw materials, copper, beryllium, copper-yttrium alloy, copper-titanium alloy, copper-manganese alloy, and nano ytterbium powder (D90=60 nm) are accurately weighed according to the mass. The raw material usage meets the requirements that beryllium accounts for 2.2 wt% of the raw materials, yttrium accounts for 0.42 wt%, titanium accounts for 1.33 wt%, manganese accounts for 0.28 wt%, and ytterbium accounts for 0.14 wt%;

[0025] (S2) The raw materials are added to a vacuum induction furnace, and heated to 1580 DEG C under argon atmosphere, so that the raw materials are completely melted. Then, the covering agent (a mixture of graphite flake, borax and calcium fluoride according to the mass ratio of 5:2:4, and the particle size is 30-60 μm) is spread on the molten material, and the molten material is smelted for 5 h under the stirring condition of graphite rod. After standing, the slag is removed, and the molten material is poured into a mold at 1150 DEG C, and then cooled to obtain a beryllium copper alloy ingot.

[0026] (S3) The beryllium copper alloy ingot is milled to a thickness of 1 mm, and then solid solution treated at 900 DEG C for 1 h. The deformation treatment is performed by cold working with a deformation of 70%, and then aged at 330 DEG C for 1.5 h under the microwave condition of 300 W power and 800 MHz frequency. Then, the product beryllium copper alloy is obtained by cooling to room temperature at a cooling rate of 2 DEG C / min.

[0027] Examples 2-5, Comparative Examples 1-5

[0028] The preparation process of Examples 2-5 and Comparative Examples 1-5 is the same as Example 1, except that the proportion of raw materials in step S1 is different, as shown in Table 1 below. Among them, Comparative Examples 1-5 are based on Example 1, respectively without metal Y, Ti, Mn and Yb content changes.

[0029] Table 1 Metal content (wt%) of alloy raw materials

[0030]

[0031]

[0032] Example 6

[0033] The preparation process is the same as Example 1, except that in step (S1), the D90 of the raw material nanometer ytterbium powder is 100 nm.

[0034] Example 7

[0035] The preparation process is the same as Example 1, except that in step (S3), the aging treatment is at 400W power, frequency 600MHz microwave conditions, aging treatment at 350℃ for 1.5h, and then cooling to room temperature at a rate of 3℃ / min.

[0036] Example 8

[0037] The preparation process is the same as Example 1, except that in step (S3), the aging treatment temperature is 370℃ and the aging treatment time is 1.5h.

[0038] Example 9

[0039] The preparation process is the same as Example 1, except that in step (S3), the aging treatment temperature is 320℃.

[0040] Comparative Example 6

[0041] The preparation process is the same as Example 1, except that in step 3, the aging treatment is not carried out under microwave conditions.

[0042] Comparative Example 7

[0043] The preparation process is the same as Example 1, except that in step 3, after aging treatment, air cooling instead of slow and smooth cooling rate of 2℃ / min.

[0044] Application Example

[0045] The beryllium copper alloy prepared in the above examples and comparative examples was tested for performance, and the results are shown in Table 2 below.

[0046] Tensile strength, yield strength test method: GB / T 228.1-2021;

[0047] Test method of elongation: GB / T 34505-2017;

[0048] Test method of elastic modulus: GB / T 22315-2008;

[0049] Test method of hardness: GB / T 4340.1-2024;

[0050] Test method of stress relaxation resistance: GB / T 39152-2020, after 500h treatment at 200℃.

[0051] Table 2 Properties of beryllium copper alloy

[0052]

[0053]

[0054] From the data in Table 2, it can be seen that the beryllium copper alloy prepared by the preparation method has excellent performance. Through the optimization of the proportion of each metal component, the aging treatment under the condition of microwave assistance and the slow cooling step after the aging treatment, the performance indicators of the beryllium copper alloy are improved.

Claims

1. A method for preparing a beryllium copper alloy, characterized in that, Includes the following steps: (S1) Accurately weigh the following raw materials according to their weight: copper, beryllium, copper-yttrium alloy, copper-titanium alloy, copper-manganese alloy, and nano-ytterbium powder; the raw material amounts should meet the following requirements: beryllium accounts for 1.8-2.6 wt%, yttrium 0.3-0.5 wt%, titanium 1.1-1.8 wt%, manganese 0.2-0.4 wt%, and ytterbium 0.12-0.17 wt%. (S2) Add the raw materials to a vacuum induction furnace and heat them to 1400-1600℃ under an inert atmosphere. After the raw materials are completely melted, spread a covering agent on the melt, melt under stirring, let stand, remove slag, and pour the melt into a mold at 1100-1200℃ to obtain beryllium copper alloy ingots. (S3) The beryllium copper alloy ingot is successively subjected to milling treatment, solution treatment, cold working deformation treatment and aging treatment to obtain the product beryllium copper alloy. The aging treatment is carried out at 320-380℃ for 1-2 hours under microwave conditions with a power of 200-450W and a frequency of 600-1000MHz, and then slowly cooled to room temperature at a cooling rate of 1-4℃ / min.

2. The preparation method according to claim 1, characterized in that, In step (S1), the purity of each raw material is ≥99.9%, and the content of phosphorus, arsenic and lead is ≤5ppm.

3. The preparation method according to claim 1, characterized in that, In step (S1), the yttrium content in the copper-yttrium alloy is 3-5 wt%, the titanium content in the copper-titanium alloy is 6-10 wt%, and the manganese content in the copper-manganese alloy is 6-10 wt%.

4. The preparation method according to claim 1, characterized in that, In step (S1), the particle size D90 of the nano-ytterbium powder is 60-100 nm.

5. The preparation method according to claim 1, characterized in that, In step (S2), the inert atmosphere is argon, and the covering agent is at least one of graphite flakes, borax, and calcium fluoride; the melting is carried out under the stirring condition of a graphite stirring rod to make the melt uniformly mixed, and the melting time is 3-5 hours.

6. The preparation method according to claim 5, characterized in that, In step (S2), the covering agent is a compound mixture of graphite flakes, borax, and calcium fluoride in a mass ratio of 3-5:2-3:3-5; the particle size of the covering agent is 20-100 μm.

7. The preparation method according to claim 1, characterized in that, In step (S3), the milling process involves milling off 1-2 mm from the surface; the solution treatment temperature is 850-930℃, and the treatment time is 1-3 hours; the deformation amount of the cold working deformation process is 50-80%.

8. The preparation method according to claim 1, characterized in that, In step (S3), the aging treatment is carried out at 300-400℃ for 1-3 hours under microwave conditions with a power of 200-500W and a frequency of 600-1500MHz, followed by slow cooling to room temperature at a cooling rate of 1-5℃ / min.

9. The preparation method according to claim 1, characterized in that, The aging process involves treating the food at 330-350℃ for 1-1.5 hours under microwave conditions with a power of 300-400W and a frequency of 600-800MHz, followed by slow cooling to room temperature at a rate of 2-3℃ / min.

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