A gradient columnar crystal electromagnetic wire conductor and its preparation method

Abstract

The present invention provides a gradient columnar crystal electromagnetic wire conductor and a preparation method thereof. For the gradient columnar crystal electromagnetic wire conductor of the present invention, the surface layer is a coarse crystal structure and the core is a fine crystal structure along the cross-sectional direction of the conductor, and the columnar crystal structure is along the axial direction of the conductor. The present invention first adopts a drawing and continuous annealing process, controls the drawing deformation amount, annealing temperature and heating time to make the recrystallization degrees of the surface layer and the core different, and obtains a gradient crystal electromagnetic wire conductor; then adopts a directional heat treatment process, controls the drawing rate and temperature gradient to make the grain boundaries migrate directionally, and finally obtains a gradient columnar crystal electromagnetic wire conductor. The present invention prepares a gradient columnar crystal electromagnetic wire conductor for the first time. The special gradient columnar crystal structure can reduce electron scattering and relieve the skin effect. Among them, the conductivity of the copper conductor is increased to 103% IACS and the elongation is increased to 42%. The preparation method can produce a high-power and low-loss electromagnetic wire conductor and be applied to the process production line.

Description

Technical Field

[0001] The present invention belongs to the technical field of material processing, and particularly relates to a gradient columnar crystal electromagnetic wire conductor and a preparation method thereof. Background Art

[0002] Electromagnetic wire is the "heart" of special high-end motors and transformers, and is widely used in fields such as high-voltage power transmission and transformation networks, ship electromagnetic catapults, weapon launches, energy generation, and rail transit. Conductivity is the core index of electromagnetic wire, which directly affects the performance and efficiency of electromagnetic wire.

[0003] The conductivity of the electromagnetic wire conductor is determined by the material structure. The transverse grain boundaries perpendicular to the current direction in the material structure will scatter electrons, thereby reducing the conductivity. In addition, there is a skin effect when alternating current is passed through the conductor, and the current is concentrated on the surface of the conductor, thereby increasing the effective resistance and deteriorating the conductivity. According to Joule's law, the lower the conductivity, the higher the resistance and the more heat loss. Therefore, improving the conductivity of the electromagnetic wire conductor is of great significance for reducing heat loss and improving energy utilization efficiency.

[0004] Taking copper conductors as an example, the currently widely used isometric crystal structure copper conductors produced from low-oxygen or oxygen-free copper rod blanks, and the conductivity cannot be broken through. In addition, single-crystal structure copper conductors have better conductivity. However, the diameter of single-crystal copper blanks is relatively large, and it is necessary to go through multiple drawing processes to reach the final diameter. Drawing will increase crystal defects such as deformation twins in single-crystal copper, and intermediate annealing treatment is required. However, recrystallization will occur when annealing above 400°C, resulting in grain boundaries that significantly reduce the conductivity, and the length of single-crystal copper is limited due to its special preparation process.

[0005] For the above reasons, it is urgent to develop a new structure high-conductivity electromagnetic wire conductor and a preparation method thereof to optimize the design of electromagnetic wire, reduce costs, and reduce energy losses. Summary of the Invention

[0006] The purpose of the present invention is to provide a gradient columnar crystal electromagnetic wire conductor and a preparation method thereof to reduce electron scattering and alleviate the skin effect, and to realize the manufacture of a high-conductivity electromagnetic wire conductor.

[0007] A gradient columnar crystal electromagnetic wire conductor, starting from the center of the conductor, along the cross-sectional direction of the conductor from the inside to the outside, the grain size changes from fine grains to coarse grains in a gradient manner, and the columnar crystal structure is along the axial direction of the conductor.

[0008] Preferably, the electromagnetic wire conductor is divided into a surface layer structure and a core structure along its cross-sectional direction. The interface between the surface layer structure and the core structure is defined by a circle with the center of the conductor as the center, and the radius of the circle where the core structure is located is 30-70% of the radius of the electromagnetic wire conductor.

[0009] Preferably, the average grain size of the surface layer structure is 20-200 μm, the average grain size of the core structure is 2-20 μm, and the maximum aspect ratio of the columnar crystal is 2-7.

[0010] The preparation method of the gradient columnar crystal magnet wire conductor described above specifically includes the following steps:

[0011] Step 1: Perform single-pass drawing on the magnet wire blank.

[0012] Step 2: Repeat the single-pass drawing in Step 1 until a magnet wire conductor with the required diameter is obtained.

[0013] Step 3: Continuously anneal the magnet wire conductor obtained in Step 2 to obtain a gradient crystal magnet wire conductor.

[0014] Step 4: Perform directional heat treatment on the gradient crystal magnet wire conductor obtained in Step 3.

[0015] Step 5: Repeat Step 4 until a gradient columnar crystal magnet wire conductor is obtained.

[0016] Preferably, in Step 1, the magnet wire blank is made of a copper rod or an electrician's round aluminum rod, and the single-pass drawing deformation amount is between 20% and 40%.

[0017] Preferably, in Step 2, the number of times of repeating the single-pass drawing in Step 1 is 5-20 times.

[0018] Preferably, in Step 3, when performing continuous annealing, the annealing temperature is 500-800 °C, the heating time is 1-10 s, the protective gas is air or argon, and the cooling method is air cooling or water cooling.

[0019] Preferably, in Step 4, when performing directional heat treatment, the temperature in the hot end area is 700-800 °C, the temperature in the cold end area is room temperature, the length of the hot zone is 30-50 mm, and the drawing rate of the magnet wire conductor is 5-20 mm / s.

[0020] Preferably, in Step 5, the number of repetitions is 1-3 times.

[0021] Compared with the prior art, the present invention has the following remarkable advantages:

[0022] Through the technical solution of the present invention, a magnet wire conductor with a gradient columnar crystal structure is obtained for the first time, the conductivity of the copper conductor is increased to 103% IACS, and the elongation is increased to 42%; the preparation method can be applied to an industrial production line and used for industrial-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of reducing electron scattering and alleviating the skin effect by the gradient columnar crystal structure of the gradient columnar crystal magnet wire conductor of the present invention.

[0024] Figure 2 This is a comparison of the microstructure of the gradient columnar crystal electromagnetic wire conductor (a) of the present invention and the traditional electromagnetic wire conductor (b). Specific Embodiments

[0025] The present invention will be further described in detail below in conjunction with embodiments and drawings.

[0026] Combined with Figure 1 , the principle of the present invention is as follows: First, a single-pass drawing and continuous annealing process is adopted. During the drawing process, the grains in the conductor microstructure are deformed and elongated to form a fibrous structure. Residual stress and lattice distortion stored energy are generated during this deformation process, providing a driving force for the subsequent recrystallization process. Subsequently, continuous annealing occurs, and new grains nucleate and grow to replace the original deformed grains. The surface temperature of the conductor is high and the heating time is long, while the core temperature is low and the heating time is short. According to the kinetics of recrystallization and grain growth, the higher the temperature and the longer the time, the larger the recrystallized grains. By controlling the deformation amount, continuous annealing temperature, and heating time, a gradient crystal electromagnetic wire conductor is obtained. Then, a directional heat treatment process is adopted to control the drawing rate and temperature gradient, so that the grains grow directionally along the axis during the recrystallization process, the grain boundaries migrate directionally, and the transverse grain boundaries become fewer and fewer, and finally a gradient columnar crystal electromagnetic wire conductor is obtained.

[0027] Example 1

[0028] The method of the present invention specifically includes the following steps:

[0029] Step 1: Perform single-pass drawing on a low-oxygen copper rod electromagnetic wire blank with a diameter of 8 mm and a grade of T1M20, and the deformation amount is 30%;

[0030] Step 2: Repeat Step 1 ten times to obtain an electromagnetic wire conductor with a diameter of 1 mm;

[0031] Step 3: Perform continuous annealing on the electromagnetic wire conductor obtained in Step 2, the temperature is 800 °C, the heating time is 1 s, the protective gas is argon, and the cooling method is water cooling to obtain a gradient crystal electromagnetic wire conductor;

[0032] Step 4: Perform directional heat treatment on the gradient crystal electromagnetic wire conductor obtained in Step 3. The temperature in the hot end region is controlled at 750 °C, the temperature in the cold end region is controlled around room temperature, the length of the hot zone is 40 mm, and the drawing rate of the electromagnetic wire conductor is 15 mm / s;

[0033] Step 5: Repeat Step 4 once to obtain a gradient columnar crystal electromagnetic wire conductor. The SEM is as shown in a in Figure 2 . Compared with the microstructure of the traditional electromagnetic wire conductor ( Figure 2 b in

[0034] After testing, the conductivity of the copper conductor of the magnet wire is increased to 103% IACS, and the elongation is increased to 42%; the preparation method can be applied to the process pipeline and used for industrial-scale production.

[0035] Example 2

[0036] The method described in the present invention specifically includes the following steps:

[0037] Step 1: Perform single-pass drawing on the low-oxygen copper rod magnet wire blank with a diameter of 8 mm and a grade of T1M20, and the deformation amount is 30%;

[0038] Step 2: Repeat Step 1 ten times to obtain a magnet wire conductor with a diameter of 1 mm;

[0039] Step 3: Continuously anneal the magnet wire conductor obtained in Step 2 at a temperature of 500 °C, a heating time of 1 s, an inert gas of argon, and a water cooling method to obtain a gradient crystal magnet wire conductor;

[0040] Step 4: Perform directional heat treatment on the gradient crystal magnet wire conductor obtained in Step 3, control the temperature in the hot end region at 750 °C, control the temperature in the cold end region at about room temperature, the length of the hot zone is 40 mm, and the drawing rate of the magnet wire conductor is 15 mm / s;

[0041] Step 5: Repeat Step 4 once to obtain a gradient columnar crystal magnet wire conductor. The average grain size of the fine crystal structure in the core is 2 μm, the average grain size of the coarse crystal structure on the surface is 20 μm, and the maximum aspect ratio of the columnar crystal is 7. The conductivity of the copper conductor of the magnet wire is increased to 101.5% IACS, and the elongation is increased to 44%.

[0042] Example 3

[0043] The method described in the present invention specifically includes the following steps:

[0044] Step 1: Perform single-pass drawing on the low-oxygen copper rod magnet wire blank with a diameter of 8 mm and a grade of T1M20, and the deformation amount is 30%;

[0045] Step 2: Repeat Step 1 ten times to obtain a magnet wire conductor with a diameter of 1 mm;

[0046] Step 3: Continuously anneal the magnet wire conductor obtained in Step 2 at a temperature of 800 °C, a heating time of 10 s, an inert gas of argon, and a water cooling method to obtain a gradient crystal magnet wire conductor;

[0047] Step 4: Perform directional heat treatment on the gradient crystal magnet wire conductor obtained in Step 3, control the temperature in the hot end region at 750 °C, control the temperature in the cold end region at about room temperature, the length of the hot zone is 40 mm, and the drawing rate of the magnet wire conductor is 15 mm / s;

[0048] Step 5: Repeat Step 4 once to obtain a gradient columnar crystal magnet wire conductor. The average grain size of the fine crystal structure in the core is 20 μm, the average grain size of the coarse crystal structure on the surface is 200 μm, and the maximum aspect ratio of the columnar crystals is 7. The conductivity of the magnet wire copper conductor is increased to 102.4% IACS, and the elongation is increased to 35%.

[0049] Example 4

[0050] The method of the present invention specifically includes the following steps:

[0051] Step 1: Perform single-pass drawing on a low-oxygen copper rod magnet wire blank with a diameter of 8 mm and a grade of T1M20, and the deformation amount is 30%;

[0052] Step 2: Repeat Step 1 ten times to obtain a magnet wire conductor with a diameter of 1 mm;

[0053] Step 3: Continuously anneal the magnet wire conductor obtained in Step 2 at a temperature of 800 °C, a heating time of 1 s, an inert gas of argon, and a water-cooling cooling method to obtain a gradient crystal magnet wire conductor;

[0054] Step 4: Perform directional heat treatment on the gradient crystal magnet wire conductor obtained in Step 3. The temperature in the hot end region is controlled at 750 °C, the temperature in the cold end region is controlled around room temperature, the length of the hot zone is 40 mm, and the drawing rate of the magnet wire conductor is 5 mm / s;

[0055] Step 5: Repeat Step 4 once to obtain a gradient columnar crystal magnet wire conductor. The average grain size of the fine crystal structure in the core is 2 μm, the average grain size of the coarse crystal structure on the surface is 200 μm, and the maximum aspect ratio of the columnar crystals is 2. The conductivity of the magnet wire copper conductor is increased to 102% IACS, and the elongation is increased to 41%.

[0056] Example 5

[0057] The method of the present invention specifically includes the following steps:

[0058] Step 1: Perform single-pass drawing on a low-oxygen copper rod magnet wire blank with a diameter of 8 mm and a grade of T1M20, and the deformation amount is 30%;

[0059] Step 2: Repeat Step 1 ten times to obtain a magnet wire conductor with a diameter of 1 mm;

[0060] Step 3: Continuously anneal the magnet wire conductor obtained in Step 2 at a temperature of 800 °C, a heating time of 1 s, an inert gas of argon, and a water-cooling cooling method to obtain a gradient crystal magnet wire conductor;

[0061] Step 4: Perform directional heat treatment on the gradient crystal electromagnetic wire conductor obtained in Step 3. The temperature in the hot end region is controlled at 750 °C, the temperature in the cold end region is controlled around room temperature, the length of the hot zone is 40 mm, and the drawing rate of the electromagnetic wire conductor is 20 mm / s;

[0062] Step 5: Repeat Step 4 once to obtain a gradient columnar crystal electromagnetic wire conductor. The average grain size of the fine crystal structure in the core is 2 μm, the average grain size of the coarse crystal structure on the surface is 200 μm, and the maximum aspect ratio of the columnar crystal is 5. The conductivity of the electromagnetic wire copper conductor is increased to 102.6% IACS, and the elongation is increased to 42%.

[0063] Comparative Example 1

[0064] The method described in the present invention specifically includes the following steps:

[0065] Step 1: Perform single-pass drawing on a low-oxygen copper rod electromagnetic wire blank with a diameter of 8 mm and grade T1M20, and the deformation amount is 30%;

[0066] Step 2: Perform continuous annealing on the electromagnetic wire blank after drawing in Step 1. The temperature is 800 °C, the heating time is 20 s, the protective gas is argon, and the cooling method is water cooling;

[0067] Step 3: Repeat Steps 1 to 2 ten times to obtain a gradient crystal electromagnetic wire conductor with a diameter of 1 mm;

[0068] Step 4: Perform directional heat treatment on the gradient crystal electromagnetic wire conductor obtained in Step 3. The regional heating temperature is 750 °C, the length of the hot zone is 40 mm, and the drawing rate of the electromagnetic wire conductor is 15 mm / s;

[0069] Step 5: Repeat Step 4 once to obtain an electromagnetic wire conductor. The average grain size of the fine crystal structure in the core is 50 μm, the average grain size of the coarse crystal structure on the surface is 200 μm, and the maximum aspect ratio of the columnar crystal is 7. The fine crystal structure in the core is too large, the conductivity of the electromagnetic wire copper conductor is 102.5% IACS, and the elongation is reduced to 29%.

[0070] Comparative Example 2

[0071] The method described in the present invention specifically includes the following steps:

[0072] Step 1: Perform single-pass drawing on a low-oxygen copper rod electromagnetic wire blank with a diameter of 8 mm and grade T1M20, and the deformation amount is 30%;

[0073] Step 2: Perform continuous annealing on the electromagnetic wire blank after drawing in Step 1. The temperature is 500 °C, the heating time is 0.5 s, the protective gas is argon, and the cooling method is water cooling;

[0074] Step 3: Repeat Step 1 to Step 2 for 10 times to obtain a gradient crystal electromagnetic wire conductor with a diameter of 1 mm;

[0075] Step 4: Perform directional heat treatment on the gradient crystal electromagnetic wire conductor obtained in Step 3, with a regional heating temperature of 750 °C, a hot zone length of 40 mm, and a drawing rate of the electromagnetic wire conductor of 15 mm / s;

[0076] Step 5: Repeat Step 4 once to obtain an electromagnetic wire conductor. The average grain size of the fine crystal structure in the core is 2 μm, the average grain size of the coarse crystal structure on the surface is 5 μm, and the maximum aspect ratio of the columnar crystal is 7. The coarse crystal structure on the surface is too small, and the conductivity of the electromagnetic wire copper conductor is reduced to 98.7% IACS and the elongation is 44%.

[0077] Comparative Example 3

[0078] The method of the present invention specifically includes the following steps:

[0079] Step 1: Perform single-pass drawing on a low-oxygen copper rod electromagnetic wire blank with a diameter of 8 mm and a grade of T1M20, with a deformation amount of 30%;

[0080] Step 2: Perform continuous annealing on the electromagnetic wire blank after drawing in Step 1, with a temperature of 800 °C, a heating time of 1 s, an inert gas of argon, and a water cooling method;

[0081] Step 3: Repeat Step 1 to Step 2 for 10 times to obtain a gradient crystal electromagnetic wire conductor with a diameter of 1 mm;

[0082] Step 4: Perform directional heat treatment on the gradient crystal electromagnetic wire conductor obtained in Step 3, with a regional heating temperature of 750 °C, a hot zone length of 40 mm, and a drawing rate of the electromagnetic wire conductor of 3 mm / s;

[0083] Step 5: Repeat Step 4 three times to obtain an electromagnetic wire conductor. The average grain size of the fine crystal structure in the core is 2 μm, the average grain size of the coarse crystal structure on the surface is 200 μm, and the maximum aspect ratio of the columnar crystal is 1, showing an equiaxed crystal. The conductivity of the electromagnetic wire copper conductor is reduced to 100% IACS and the elongation is 42%.

[0084] Comparative Example 4

[0085] The method of the present invention specifically includes the following steps:

[0086] Step 1: Perform single-pass drawing on a low-oxygen copper rod electromagnetic wire blank with a diameter of 8 mm and a grade of T1M20, with a deformation amount of 30%;

[0087] Step 2: Perform continuous annealing on the electromagnetic wire blank after drawing in Step 1, with a temperature of 800 °C, a heating time of 1 s, an inert gas of argon, and a water cooling method;

[0088] Step 3: Repeat Step 1 to Step 2 for 10 times to obtain a gradient crystal electromagnetic wire conductor with a diameter of 1 mm;

[0089] Step 4: Perform directional heat treatment on the gradient crystal electromagnetic wire conductor obtained in Step 3, with a regional heating temperature of 750 °C, a hot zone length of 40 mm, and a drawing rate of the electromagnetic wire conductor of 45 mm / s;

[0090] Step 5: Repeat Step 4 for 3 times to obtain an electromagnetic wire conductor, with an average grain size of 2 μm for the fine crystal structure in the core, an average grain size of 200 μm for the coarse crystal structure on the surface, a maximum aspect ratio of columnar crystals of 1, showing equiaxed crystals. The conductivity of the electromagnetic wire copper conductor is reduced to 100% IACS, and the elongation is 42%.

Claims

1. A gradient columnar crystal electromagnetic wire conductor, characterized in that: Starting from the center of the conductor, along the cross-section of the conductor from the inside to the outside, the grain size changes gradually from fine grains to coarse grains, and along the axial direction of the conductor is a columnar crystal structure; Among them, the electromagnetic wire conductor is divided into a surface tissue and a core tissue along its cross-sectional direction, the interface between the surface tissue and the core tissue is defined by a circle, the center of the circle is the center of the conductor, the average grain size of the surface tissue is 20~200μm, the average grain size of the core tissue is 2~20μm, and the maximum aspect ratio of the columnar crystal is 2~7.

2. The gradient columnar crystal electromagnetic wire conductor according to claim 1, characterized in that: The radius of the circle where the core structure is located is 30~70% of the radius of the electromagnetic wire conductor.

3. The method for preparing a gradient columnar crystal electromagnetic wire conductor according to any one of claims 1 to 2, characterized in that: The following steps are involved: Step 1: single-pass drawing of the electromagnetic wire blank; Step 2: Repeat the single-pass drawing of step 1 until the electromagnetic wire conductor of the required diameter is obtained; Step 3: Continuously annealing the electromagnetic wire conductor obtained in step 2 to obtain a gradient crystal electromagnetic wire conductor; Step 4: performing directional heat treatment on the gradient crystal electromagnetic wire conductor obtained in step 3; Step 5: Repeat step 4 until a gradient columnar crystal electromagnetic wire conductor is obtained.

4. The method according to claim 3, characterized in that In step 1, the electromagnetic wire blank is made of copper rod or electrical round aluminum rod, and the single-pass drawing deformation is between 20% and 40%.

5. The method according to claim 3, characterized in that In step 2, the single-pass drawing of step 1 is repeated 5 to 20 times.

6. The method according to claim 3, characterized in that In step three, when continuous annealing is performed, the annealing temperature is 500-800° C., the heating time is 1-10 seconds, the protective gas is air or argon, and the cooling method is air cooling or water cooling.

7. The method according to claim 3, characterized in that In step 4, when directional heat treatment is performed, the temperature of the hot end area is 700~800°C, the temperature of the cold end area is room temperature, the length of the hot zone is 30~50mm, and the pulling rate of the electromagnetic wire conductor is 5~20mm / s.

8. The method according to claim 3, characterized in that In step 5, repeat 1 to 3 times.

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