A method for near-isotropic high-beryllium-content beryllium copper slab cooling free forging

Abstract

The application relates to a kind of near-isotropic high-beryllium-content beryllium copper slab cooling free forging methods, and relates to a kind of forging method.The application aims to solve the problems of low beryllium content in the strip prepared by the existing method, obvious edge crack phenomenon of high-beryllium-content beryllium copper strip, reduced processing efficiency and large equipment investment.Method: I, preparation of ingot;II, cooling forging;III, quenching and post-treatment, to obtain high-beryllium-content beryllium copper strip for multiplier pole.The application can realize the preparation of beryllium copper strip for multiplier pole with beryllium content up to 3.5wt.%, and can greatly break the second phase by using cooling multi-directional forging, inhibit the generation of needle-like dynamic precipitation structure, obtain near-isotropic plate, and compared with rolling forming and extrusion forming, can obtain dense structure, large coil weight finished product.The application can obtain a kind of near-isotropic high-beryllium-content beryllium copper slab free forging method.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for forging. BACKGROUND

[0002] High-beryllium-content beryllium copper strip has important application value and broad application prospects in aerospace, transportation, and electrical and electronic fields. Chinese patent CN202210389957.4 uses multi-pass rolling + solid solution to prepare beryllium copper alloy strip with a beryllium content of 1.8-2.1wt.%, however, the strip prepared by this method has the following problems: first, the beryllium content is low, which cannot meet the requirements of the secondary electron emission coefficient of high-performance photomultiplier tubes; second, due to the hard and brittle second phase of beryllium copper alloy, after multi-pass rolling, the edge cracking of beryllium copper strip is very obvious, and it must be milled to trim the edge, which reduces the processing efficiency; third, if large-scale coiled material is to be prepared, a wide hot rolling mill needs to be invested to prepare large-scale heavy coiled material, which leads to large equipment investment; Chinese patent CN201810809226.4 uses extrusion + rolling to prepare 2.5~3.5wt.% beryllium copper alloy strip, but due to the increase of beryllium content, a large amount of hard and brittle second phase is produced, which increases the deformation resistance, which puts higher requirements on the extruder, increases the energy consumption of the extruder, and increases the loss of the extrusion die, which increases the manufacturing cost and reduces the processing efficiency; at the same time, the higher extrusion temperature makes the cooling rate of the billet not enough during quenching, which makes it easy to produce acicular γ phase in the slab, and these acicular γ phases easily lead to deformation cracking during finish rolling, and the anisotropy is serious, which brings difficulties to the high-precision processing of the subsequent large-coiled strip. Therefore, it is of great significance to develop a low-cost, near-isotropic, and acicular γ phase-free large-coiled beryllium copper slab preparation method for the engineering application of such material. SUMMARY

[0003] The purpose of the present application is to solve the problems of low beryllium content in the strip prepared by the existing method, obvious edge cracking of high-beryllium-content beryllium copper strip, reduced processing efficiency, and large equipment investment, and to provide a method for near-isotropic high-beryllium-content beryllium copper slab free forging.

[0004] A method for near-isotropic high-beryllium-content beryllium copper slab free forging by cooling, which is completed according to the following steps:

[0005] I. Preparation of ingot:

[0006] Using pure copper and beryllium copper intermediate alloy as raw materials, the raw materials are sequentially put into a vacuum medium frequency furnace for melting, then refined, slagging, and standing, and finally semi-continuous casting and car skin to obtain a billet;

[0007] II. Forging:

[0008] First, the blank is homogenized, and then temperature reduction multi-directional forging is carried out;

[0009] The temperature reduction multi-directional forging in step two is specifically completed by the following steps:

[0010] ①, pre-forging:

[0011] The homogenized blank is forged for one cycle under the conditions that the temperature is 810 DEG C ~ 830 DEG C and the reduction is 20%~40%, and the pre-forged blank is obtained;

[0012] ②, intermediate forging:

[0013] The pre-forged blank is forged for 4~7 cycles under the conditions that the temperature is 760 DEG C ~ 800 DEG C and the reduction is 20%~40%, and the intermediate forged blank is obtained;

[0014] ③, finish forging:

[0015] The intermediate forged blank is forged for one cycle under the conditions that the temperature is 740 DEG C ~ 760 DEG C and the reduction is 10%~30%, and the beryllium copper plate blank after finish forging is obtained;

[0016] III. Quenching:

[0017] The beryllium copper plate blank after finish forging is quenched, and the quenched beryllium copper plate blank is obtained.

[0018] The advantages of the present application are:

[0019] (1), material organization is dense:

[0020] Compared with constant temperature forging, the present application adopts temperature reduction forging process, increases the pre-forging temperature, reduces the finish forging temperature, the alloy is better forgeable at high temperature, the toughness is stronger, the deformation strength is large, and the alloy is not easy to crack, the low temperature finish forging inhibits the precipitation of hard and brittle second phase, prevents grain growth, and obtains uniform and dense organization, and at the same time, the second phase can be greatly broken in the process of multi-directional forging, and the second phase uniform organization is obtained;

[0021] (2), low production cost:

[0022] Because the high beryllium content beryllium copper alloy produces hard and brittle second phase, if direct rolling + solid solution treatment is carried out, the rolling pass is more, the rolling mill is large, and the processing efficiency is low; compared with extrusion + rolling, the extrusion efficiency is low, the die wear is large, the processing flow of the present application is short, there is no die wear, and the production cost is low;

[0023] (3), the blank size is not limited:

[0024] Compared with the rolling and extrusion process subjected to the die, the free forging blank size is not limited, the ingot length can be freely controlled, and various specifications of heavy plate blanks can be flexibly prepared;

[0025] (4) Good deformation performance:

[0026] The blank is subjected to multi-directional forging by multiple times of turning along the direction perpendicular to the axial direction, the flow of the material along each direction is fully ensured, the nearly isotropic plate is obtained, the possibility of edge cracking of the material in the subsequent deformation process is reduced, and the yield rate is greatly improved;

[0027] (5) The present application can realize the preparation of the beryllium copper strip with the highest beryllium content of 3.5 wt.%, and the second phase can be broken to the greatest extent by using the cooling forging machine, the needle-like dynamic precipitation structure is inhibited, and the nearly isotropic plate is obtained, compared with the rolling and extrusion forming, the nearly isotropic plate with dense structure and heavy finished product can be obtained.

[0028] The present application can obtain a kind of nearly isotropic high beryllium content beryllium copper plate blank cooling free forging method. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a schematic diagram of the cooling multi-directional forging described in the present application;

[0030] Figure 2 It is the optical microstructure diagram of the quenched Cu-3.0Be beryllium copper plate blank obtained in step two of example 2;

[0031] Figure 3 It is the optical microstructure diagram of the quenched Cu-3.0Be beryllium copper plate blank obtained in step two of example 3;

[0032] Figure 4 It is the optical microstructure diagram of the quenched Cu-3.0Be beryllium copper plate blank obtained in step three of example 4. DETAILED DESCRIPTION

[0033] Specific implementation one: a kind of nearly isotropic high beryllium content beryllium copper plate blank cooling free forging method of the present embodiment, specifically is completed according to the following steps:

[0034] I. Preparation of ingot:

[0035] Pure copper, beryllium copper intermediate alloy is used as raw material, the raw material is sequentially put into vacuum medium frequency furnace for melting, then refining, slagging, standing, finally semi-continuous casting, car, to obtain blank;

[0036] II. Forging:

[0037] First, the blank is homogenized, and then subjected to cooling multi-directional forging;

[0038] The temperature-reducing multi-directional forging in step two is specifically completed in the following steps:

[0039] ①, pre-forging:

[0040] Under the conditions of a temperature of 810-830 DEG C and a reduction of 20-40%, the homogenized blank is forged for one cycle to obtain a pre-forged blank;

[0041] ②, intermediate forging:

[0042] Under the conditions of a temperature of 760-800 DEG C and a reduction of 20-40%, the pre-forged blank is forged for 4-7 cycles to obtain an intermediate-forged blank;

[0043] ③, finish forging:

[0044] Under the conditions of a temperature of 740-760 DEG C and a reduction of 10-30%, the intermediate-forged blank is forged for one cycle to obtain a finished beryllium copper plate blank;

[0045] III. Quenching:

[0046] The finished beryllium copper plate blank is quenched to obtain a quenched beryllium copper plate blank.

[0047] Specific implementation method two: the difference between this embodiment and specific implementation method one is that the mass fraction of beryllium in the beryllium copper intermediate alloy in step one is 10%. The other steps are the same as specific implementation method one.

[0048] Specific implementation method three: the difference between this embodiment and one of specific implementation method one or two is that the mass fraction of beryllium in the blank in step one is 2.8-3.5%, zinc, lead, tin, bismuth, cobalt, iron, chromium, cadmium are impurities, the total content of impurity elements is not more than 0.3%, and the balance is copper. The other steps are the same as specific implementation method one or two.

[0049] Specific implementation method four: the difference between this embodiment and one of specific implementation method one to three is that the size of the blank in step one is φ 300-600 mm and the height is 2-5 m. The other steps are the same as specific implementation method one to three.

[0050] Specific implementation method five: the difference between this embodiment and one of specific implementation method one to four is that the temperature of the smelting in step one is 1200-1300 DEG C and the smelting time is 30-60 min. The other steps are the same as specific implementation method one to four.

[0051] Specific implementation six: the difference between this embodiment and one of the specific implementations one to five is that the standing time in step one is 3 min to 10 min. The other steps are the same as specific implementations one to five.

[0052] Specific implementation seven: the difference between this embodiment and one of the specific implementations one to six is that the homogenization temperature in step two is 780℃ to 800℃, and the homogenization time is 12h to 20h. The other steps are the same as specific implementations one to six.

[0053] Specific implementation eight: the difference between this embodiment and one of the specific implementations one to seven is that the period in step two is 2 to 3 times of the blank along the vertical axis as one period. The other steps are the same as specific implementations one to seven.

[0054] Specific implementation nine: the difference between this embodiment and one of the specific implementations one to eight is that the thickness of the beryllium copper blank in step two is 5mm to 10mm, and the length is 4m to 7m. The other steps are the same as specific implementations one to eight.

[0055] Specific implementation ten: the difference between this embodiment and one of the specific implementations one to nine is that the beryllium copper blank after quenching is subjected to 7 to 8 passes of high-precision rolling and calendering processing in step three, and a beryllium copper strip with a thickness of 0.1 to 0.2mm for multiplication pole is obtained. The other steps are the same as specific implementations one to nine.

[0056] The following examples are used to verify the beneficial effects of the present application:

[0057] Example 1: The preparation of high beryllium content blank is completed according to the following steps:

[0058] Pure copper, beryllium copper intermediate alloy as raw material, the raw material is put into the vacuum medium frequency furnace in turn for smelting, the smelting temperature is controlled at 1250℃, smelting at 1250℃ for 30min, then refining, slagging, standing for 10min, finally semi-continuous casting, car, get blank, the composition of the blank is shown in table 1, the % in table 1 is mass fraction;

[0059] The mass fraction of beryllium in the beryllium copper intermediate alloy in step one is 10%;

[0060] The size of the blank in step one is φ 550mm.

[0061] Table 1 composition of blank

[0062]

[0063] Zn, Pb, Sn, Bi, Co, Fe, Cr and Cd in table 1 are impurities.

[0064] Example 2: A method for near-isotropic high-beryllium-content beryllium copper plate blank free forging, specifically completed according to the following steps:

[0065] I. Forging:

[0066] The one-segment blank prepared in Example 1 is homogenized, and then subjected to multi-directional forging;

[0067] The homogenization temperature in Step One is 780°C, and the homogenization time is 12 hours;

[0068] The multi-directional forging in Step One is specifically completed according to the following steps:

[0069] The homogenized blank is forged for 8 cycles at a temperature of 830°C and a reduction of 35%, to obtain a beryllium copper plate blank;

[0070] The cycle in Step One is 1 cycle with the blank being flipped 2 times along the vertical direction;

[0071] The thickness of the beryllium copper plate blank in Step One is 7.4 mm, and the length is 6.63 m;

[0072] II. Quenching:

[0073] The beryllium copper plate blank after finish forging is quenched to obtain a quenched Cu-3.0Be beryllium copper plate blank, and the mechanical properties are shown in Table 2.

[0074] Table 2: Properties of Cu-3.0Be beryllium copper plate blank prepared in Example 2

[0075]

[0076] Among them: Anisotropy coefficient = | axial mechanical properties - radial mechanical properties |

[0077] Figure 2 Optical microstructure of the quenched Cu-3.0Be beryllium copper plate blank obtained in Step Two of Example 2;

[0078] From Figure 2 and Table 2, it can be seen that due to the high forging temperature, there are a large number of hard and brittle needle-shaped phases in the quenched structure, which reduces the plasticity of the alloy, and the anisotropy of the alloy may cause cracking, and the subsequent finish rolling performance is poor.

[0079] Example 3: A method for near-isotropic high-beryllium-content beryllium copper plate blank free forging, specifically completed according to the following steps:

[0080] I. Forging:

[0081] The one-segment blank prepared in Example 1 is homogenized, and then subjected to multi-directional forging;

[0082] The temperature of the homogenization is 780℃, and the time of the homogenization is 12h;

[0083] The multi-directional forging in step one is specifically completed by the following steps:

[0084] The homogenized billet is forged for 12 cycles under the conditions of a temperature of 730℃ and a reduction of 20%, to obtain a beryllium copper plate blank;

[0085] The cycle in step one is taken as one cycle with the billet being turned over twice along the vertical direction;

[0086] The thickness of the beryllium copper plate blank in step one is 7.85mm, and the length is 6.32m;

[0087] II. Quenching:

[0088] The beryllium copper plate blank after the final forging is quenched to obtain a quenched Cu-3.0Be beryllium copper plate blank, and the mechanical properties are shown in Table 3.

[0089] Table 3 Properties of the Cu-3.0Be beryllium copper plate blank prepared in Example 3

[0090]

[0091] Wherein: the anisotropy coefficient = | axial mechanical properties - radial mechanical properties |

[0092] Figure 3 An optical microstructure diagram of the quenched Cu-3.0Be beryllium copper plate blank obtained in step two of Example 3;

[0093] From Figure 3 and Table 3, it can be seen that because the forging temperature is low, the plasticity of the alloy is high but the toughness is poor, so more cycles are needed for forging to achieve the desired thickness.

[0094] Example 4: A method for near-isotropic high-beryllium-content beryllium copper plate blank cooling free forging, specifically completed by the following steps:

[0095] I. Forging:

[0096] A section of the billet prepared in Example 1 is homogenized, and then subjected to cooling multi-directional forging;

[0097] The cooling multi-directional forging in step one is specifically completed by the following steps:

[0098] ①. Pre-forging:

[0099] The homogenized billet is forged for one cycle under the conditions of a temperature of 820℃ and a reduction of 30%, to obtain a pre-forged billet;

[0100] ii. intermediate forging:

[0101] The pre-forged blank is forged for 7 cycles at a temperature of 780°C and a reduction of 30% to obtain an intermediate-forged blank;

[0102] iii. final forging:

[0103] The intermediate-forged blank is forged for 1 cycle at a temperature of 750°C and a reduction of 20% to obtain a final-forged beryllium copper plate blank;

[0104] The cycle in step i is 1 cycle for the blank to be flipped 2 times along the vertical direction;

[0105] The beryllium copper plate blank in step i has a thickness of 7.61 mm and a length of 6.55 m, and is a beryllium copper plate blank with a dense structure, excellent deformation performance, and near-isotropy;

[0106] ii. quenching:

[0107] The final-forged beryllium copper plate blank is quenched to obtain a quenched Cu-3.0Be beryllium copper plate blank, and the mechanical properties are shown in Table 4.

[0108] Table 4 Properties of the Cu-3.0Be beryllium copper plate blank prepared in Example 4

[0109]

[0110] Among them: anisotropy coefficient = | axial mechanical properties - radial mechanical properties |

[0111] Figure 4 An optical microstructure diagram of the quenched Cu-3.0Be beryllium copper plate blank obtained in step iii of Example 4;

[0112] From Figure 4 and Table 4, it can be seen that the grain size is uniformly distributed in the temperature-reducing forging, the structure is fine, the alloy has good strength and toughness, good isotropy, good deformation capacity, and a short forging process.

Claims

1. A method of near-isotropic high-beryllium-content beryllium copper slab cooling free forging, characterized by The method is specifically completed in the following steps: I. Preparation of ingot: Taking pure copper and beryllium copper intermediate alloy as raw materials, the raw materials are sequentially put into a vacuum medium frequency furnace for melting, then refining, slagging, and standing, and finally semi-continuous casting and car skin to obtain a blank; II. Forging: First, homogenize the blank, and then perform temperature reduction multi-directional forging; The temperature reduction multi-directional forging in step two is specifically completed in the following steps: ①, pre-forging: Under the conditions of a temperature of 810-830 DEG C and a reduction of 20-40%, the homogenized blank is forged for 1 cycle to obtain a pre-forged blank; ②, intermediate forging: Under the conditions of a temperature of 760-800 DEG C and a reduction of 20-40%, the pre-forged blank is forged for 4-7 cycles to obtain an intermediate-forged blank; ③, finish forging: Under the conditions of a temperature of 740-760 DEG C and a reduction of 10-30%, the intermediate-forged blank is forged for 1 cycle to obtain a finished beryllium copper plate blank; III. Quenching: Quenching the finished beryllium copper plate blank to obtain a quenched beryllium copper plate blank.

2. A method of near-isotropic high-beryllium-content beryllium copper slab cooling free forging according to claim 1, characterized in that The mass fraction of beryllium in the beryllium copper intermediate alloy in step one is 10%.

3. A method of near-isotropic high-beryllium-content beryllium copper slab cooling free forging according to claim 1, characterized in that The mass fraction of beryllium in the blank in step one is 2.8-3.5%, zinc, lead, tin, bismuth, cobalt, iron, chromium, cadmium are impurities, the total content of impurity elements is not more than 0.3%, and the balance is copper.

4. The method of claim 1, wherein the near-isotropic high-beryllium-content beryllium copper slab is cooled at a temperature of 600 to 800°C. The size of the blank in step one is φ 300-600 mm and height 2-5 m.

5. A method of near-isotropic high-beryllium-content beryllium copper slab cooling free forging according to claim 1, characterized in that The temperature of the melting in step one is 1200-1300 DEG C, and the melting time is 30-60 min.

6. A method of near-isotropic high-beryllium-content beryllium copper slab cooling free forging according to claim 1, characterized in that The standing time in step one is 3-10 min.

7. A method of near-isotropic high-beryllium-content beryllium copper slab cooling free forging according to claim 1, characterized in that The homogenization temperature in step two is 780-800 DEG C, and the homogenization time is 12-20 h.

8. The method of near-isotropic high-beryllium-content beryllium copper slab cooling free forging according to claim 1, characterized in that The cycle in step two is 2-3 times of turning the blank vertically along the axial direction as one cycle.

9. A method of near-isotropic high-beryllium-content beryllium copper slab cooling free forging according to claim 1, characterized in that The thickness of the beryllium copper plate blank in step two is 5-10 mm, and the length is 4-7 m.

10. The method of near-isotropic high-beryllium-content beryllium copper slab cooling free forging according to claim 1, characterized in that In step three, the quenched beryllium copper plate blank is subjected to 7-8 passes of high-precision rolling and calendering to obtain a beryllium copper strip for a doubler with a thickness of 0.1-0.2 mm.

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