Oxygen-free copper alloy strip and preparation method thereof

Abstract

The invention provides an oxygen-free copper alloy strip and a preparation method thereof, and relates to the technical field of copper alloys. The oxygen-free copper alloy strip provided by the invention comprises the following components in percentage by mass: 20 to 100 ppm of Ni, 10 to 100 ppm of Si, 20 to 80 ppm of La and / or Ce, 10 to 30 ppm of Y and the balance of copper, 0.2 < = mass of Y / (mass of La and Ce) < = 0.6; the total mass ratio of Ni, Si, La, Ce and Y is less than or equal to 300ppm. The oxygen content of a finished product of the oxygen-free copper alloy strip is smaller than or equal to 18 ppm, the average grain size is smaller than or equal to 50 micrometers, the twin crystal boundary proportion is larger than or equal to 58%, the electric conductivity is 98-102.8% IACS, the hardness is 70-105 HV, and after a heat resistance test, the average grain size is smaller than or equal to 100 micrometers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of copper alloy, in particular to a non-oxygen copper alloy strip and a preparation method thereof. BACKGROUND

[0002] At present, the rapid development of high-power power transmission, new energy vehicle motor, 5G communication base station and controllable nuclear fusion device puts forward the integrated demand of "heat resistance-conduction-lightweight" for materials. The heat resistance requirement of non-oxygen copper mainly reflects its ability to keep the grain size stable and the conductivity not to decrease significantly at high temperature. The problems of conductivity attenuation, strength degradation and oxidation sensitivity of traditional non-oxygen copper (OFC) in high temperature environment gradually become prominent, which limits its application in extreme working conditions. Therefore, it is necessary to find a new alloy and its preparation method to solve the technical problem.

[0003] As a new type of high-performance copper-based material, heat-resistant non-oxygen copper can significantly improve its high-temperature stability, softening resistance and oxidation resistance through micro-alloying and precision processing technology, while maintaining the high conductivity (≥99% IACS) and low impurity characteristics of non-oxygen copper, which becomes the key direction to solve the material bottleneck in high temperature and high power scenarios.

[0004] In addition, in the field of new energy vehicles, heat-resistant non-oxygen copper can replace part of silver-based alloys to balance the cost and performance, and can also promote the expansion of copper-based materials to high value-added fields, which has significant economic and strategic value.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The first purpose of the present application is to provide a non-oxygen copper alloy strip to solve the above technical problems.

[0007] The second purpose of the present application is to provide a preparation method of the non-oxygen copper alloy strip.

[0008] In order to achieve the above purposes, the following technical solutions are adopted: In the first aspect, the present application provides a non-oxygen copper alloy strip, which comprises, by mass percentage: Ni 20-100ppm, Si 10-100ppm, La and / or Ce 20-80ppm, Y 10-30ppm, and the balance being copper. 0.2≤Y mass percentage / (La and Ce mass percentage)≤0.6; The total mass percentage of Ni, Si, La, Ce and Y is less than or equal to 300ppm.

[0009] As a further technical solution, it also includes one or more of Te and Mg; The mass percentage of Te in the oxygen-free copper alloy strip is not more than 50 ppm; The mass percentage of Mg in the oxygen-free copper alloy strip is not more than 50 ppm; The total mass percentage of Ni, Si, La, Ce, Y, Mg and Te is less than or equal to 300 ppm.

[0010] In a second aspect, the present application provides a preparation method of the above-mentioned oxygen-free copper alloy strip, comprising the following steps: According to the mass percentage, then sequentially performing melting, semi-continuous casting, hot rolling, cold rolling, recrystallization annealing, cold deformation processing and low-temperature recrystallization annealing cycle treatment, to obtain the oxygen-free copper alloy strip.

[0011] As a further technical solution, the raw materials of the oxygen-free copper alloy strip include: electrolytic copper, pure nickel, nickel-silicon alloy, copper-magnesium alloy, copper-tellurium alloy, copper-lanthanum alloy, copper-yttrium alloy and copper-cerium alloy. The raw materials further include a step of pickling to remove the surface oxide layer and impurities of the raw materials before melting.

[0012] As a further technical solution, the melting temperature is 1200-1230℃. The semi-continuous casting temperature is 1150-1220℃, and the casting speed is 75-85 mm / min.

[0013] As a further technical solution, the hot rolling opening temperature is 830-900℃. The hot rolling final rolling temperature is 650-830℃. The total processing rate of the hot rolling is 90%-98%.

[0014] As a further technical solution, the cast ingot obtained by semi-continuous casting is heated to 850-1100℃ before the hot rolling.

[0015] As a further technical solution, the cold rolling deformation amount is 74%-85%.

[0016] As a further technical solution, the recrystallization annealing is performed under a protective atmosphere. The recrystallization annealing annealing temperature is 600-650℃, and the holding time is 30-120 min.

[0017] As a further technical solution, the cold deformation processing deformation amount is 15%-30%. The low-temperature recrystallization annealing temperature is 260-370℃, and the holding time is 20-120 min. The cold deformation processing and low-temperature recrystallization annealing cycle treatment cycle number is 4-5 times.

[0018] As a further technical solution, the thickness of the oxygen-free copper alloy strip is 0.2-3 mm, and the width is greater than or equal to 600 mm.

[0019] Compared with the prior art, the present application has the following beneficial effects: The oxygen-free copper alloy strip provided by the present application introduces micro-alloying elements such as Ni, Si, Mg, Te and mixed rare earths, and through the precipitation strengthening of Ni-Si, Mg-Cu and Si-La and the inhibitory effect on grain boundary coarsening and diffusion, the grain size is refined, the alloy strength and high-temperature stability are improved; a small amount of Te addition does not affect the electrical conductivity of the alloy, while La, Mg and other elements improve the mechanical properties of the alloy and improve the cutting performance of the alloy; deep deoxidation of Mg and Y reduces the oxygen content of the alloy; by reasonably controlling the proportion of mixed rare earth elements (La, Y and Ce), the balance between strength, electrical conductivity and thermal conductivity of the copper alloy can be achieved, thereby meeting the demand for high-performance conductive materials. The finished product of the oxygen-free copper alloy strip has an oxygen content of less than or equal to 18 ppm, an average grain size of less than or equal to 50 μm, a twin grain boundary ratio of greater than or equal to 58%, an electrical conductivity of 98-102.8% IACS, and a hardness of 70-105 HV. After heat resistance testing, the average grain size is less than or equal to 100 μm. DETAILED DESCRIPTION

[0020] The embodiments of the present application will be described in detail below with reference to the embodiments and examples, but those skilled in the art will understand that the following embodiments and examples are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. Based on the examples in the present application, all other examples obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application. If the specific conditions are not specified, the conventional conditions or the conditions recommended by the manufacturer are used. If the manufacturer of the reagent or instrument is not specified, it is a conventional product that can be purchased on the market.

[0021] In a first aspect, the present application provides an oxygen-free copper alloy strip mainly composed of Cu, Ni, Si, La, Ce, Y, Mg and Te. For example, the content of Ni can be, but is not limited to, 20 ppm, 60 ppm or 100 ppm; the content of Si can be, but is not limited to, 10 ppm, 60 ppm or 100 ppm; the content of La and / or Ce can be, but is not limited to, 20 ppm, 50 ppm or 80 ppm. It should be noted that "La and / or Ce" in the present application means that it can be La, Ce or La and Ce; the content of Y can be, but is not limited to, 10 ppm, 20 ppm or 30 ppm. The total mass fraction of Ni, Si, La, Ce and Y is less than or equal to 300 ppm.

[0022] In the present application, the elements of Ni and Si are added to form Ni2Si precipitated phase in the crystal and at the grain boundary, which can significantly improve the mechanical properties of the alloy, wherein Si also forms LaSi2 with rare earth La, which has a pinning effect on the grain boundary, inhibiting grain boundary coarsening and expansion; The mixed rare earth elements are added, wherein the rare earth La element can inhibit grain boundary migration to improve the creep resistance of the alloy; the Y element can deeply deoxidize to form solid solution strengthening in the copper matrix to improve the strength and toughness of the alloy; the Ce element has good purification ability to remove impurities in cooperation with the La element to improve the electrical conductivity and ductility of the alloy. The addition of mixed rare earth elements satisfies 0.2≤Y mass percentage / (La and Ce mass percentage)≤0.6, and in this range, the comprehensive performance of the alloy is best. When Y mass percentage / (La and Ce mass percentage)>0.6, Y is excessive, which leads to a sharp drop in electrical conductivity, aggravation of electron scattering, and saturation or even decline of mechanical properties; when Y mass percentage / (La and Ce mass percentage)<0.2, La / Ce dominates the electrical conductivity but the strengthening is insufficient, and the grain refinement effect is weakened. By reasonably controlling the ratio of Y, La and Ce, the balance between the strength and electrical conductivity of the copper alloy can be achieved, thereby meeting the demand for high-performance conductive materials.

[0023] In some preferred embodiments, one or more of Te and Mg are further included; The mass percentage of Te in the oxygen-free copper alloy strip is not more than 50ppm; The mass percentage of Mg in the oxygen-free copper alloy strip is not more than 50ppm; The total mass percentage of Ni, Si, La, Ce, Y, Mg and Te is less than or equal to 300ppm.

[0024] In the present application, the addition of Mg element can further reduce the oxygen content of the alloy, while forming MgCu2 phase to play the role of aging hardening, and can also inhibit grain growth at high temperature to improve the high temperature stability of the material; the addition of Te element does not affect the electrical conductivity of the alloy, disperses to refine the grains, and cooperates with La, Mg and the like to improve the mechanical properties of the alloy and improve the cutting performance of the alloy.

[0025] In a second aspect, the present application provides a preparation method of the above-mentioned oxygen-free copper alloy strip, comprising the following steps: According to the mass percentage, then sequentially performing melting, semi-continuous casting, hot rolling, cold rolling, recrystallization annealing, cold deformation processing and low temperature recrystallization annealing cycle treatment, an oxygen-free copper alloy strip is prepared.

[0026] The preparation method is simple, the alloy strip blank after hot rolling is subjected to cold rolling and a cyclic 'cold deformation processing + low-temperature recrystallization annealing' process, multiple strain-induced grain boundary migration, the average grain size is increased, and the proportion of twin crystal regions is increased (the grain boundary energy of the twin crystal grain boundary is low, and the migration rate of the grain boundary is also low, and the increase of the proportion of the twin crystal grain boundary can improve the material organization stability, and the heat resistance of the alloy is improved).

[0027] In the preparation method, the raw materials are electrolytic copper, pure nickel, 60% Ni-Si intermediate alloy, 10% Cu-Mg intermediate alloy, 20% Cu-Te intermediate alloy, 10% Cu-La intermediate alloy, 20% Cu-Y intermediate alloy, and 15% Cu-Ce intermediate alloy, the surface of the raw materials is subjected to pickling treatment and cleaning and drying, and the treated raw materials are sequentially placed into a smelting furnace. The composite covering agent needs to be baked at 800 DEG C for 4 hours before use to remove moisture; In the pouring process, the mixture of baked and dried deslagging agent and graphite powder is covered in the runner, the composite covering agent is covered in the crystallizer, the converter process is protected by burning natural gas, the ceramic filter screen is installed on the runner to avoid the oxidation slag such as silicon and magnesium from being rolled into the crystallizer to cause slag inclusion, the pouring pipe is buried in the crystallizer to a depth of 3.5-4.5 cm, and the casting machine is started when the melt is about to fill the crystallizer; Recrystallization annealing is used to eliminate the work hardening of the material after cold processing, restore plasticity and deformation ability, and improve the alloy organization and performance; In the application, the 'cold deformation processing and low-temperature recrystallization annealing cyclic treatment' refers to the cyclic 'cold deformation processing + low-temperature recrystallization annealing' process, and the cycle number should not be too high, otherwise the grain size will be coarsened, and the alloy performance will be affected.

[0028] In some preferred embodiments, the raw materials of the oxygen-free copper alloy strip include electrolytic copper, pure nickel, nickel-silicon alloy, copper-magnesium alloy, copper-tellurium alloy, copper-lanthanum alloy, copper-yttrium alloy and copper-cerium alloy. Before smelting, the raw materials also include the step of pickling to remove the oxidation layer and impurities on the surface of the raw materials.

[0029] In some preferred embodiments, the acid solution for pickling can be, but is not limited to, dilute sulfuric acid (solute mass fraction 5%-20%), dilute hydrochloric acid (solute mass fraction 5%-20%) or a mixed solution of dilute sulfuric acid and hydrogen peroxide (solute mass fraction 3%-10%), and the pickling time is 1-20 minutes (determined according to the thickness of the oxide skin).

[0030] In some preferred embodiments, the smelting temperature can be, but is not limited to, 1200 DEG C, 1210 DEG C or 1230 DEG C.

[0031] In some preferred embodiments, the semi-continuous casting temperature can be, but is not limited to, 1150°C, 1180°C or 1220°C, and the casting speed can be, but is not limited to, 75 mm / min, 80 mm / min or 85 mm / min.

[0032] In some preferred embodiments, the hot rolling starting temperature can be, but is not limited to, 830°C, 860°C or 900°C. The hot rolling finishing temperature can be, but is not limited to, 650°C, 750°C or 830°C. The total reduction ratio of the hot rolling can be, but is not limited to, 90%, 94% or 98%.

[0033] In some preferred embodiments, the hot rolling is performed after the cast ingot obtained by semi-continuous casting is heated to 850-1100°C.

[0034] In some preferred embodiments, the cold rolling deformation can be, but is not limited to, 74%, 80% or 85%.

[0035] In some preferred embodiments, the recrystallization annealing is performed in a protective atmosphere. The recrystallization annealing temperature can be, but is not limited to, 600°C, 630°C or 650°C, and the holding time can be, but is not limited to, 30 min, 70 min or 120 min.

[0036] In some preferred embodiments, the cold deformation processing deformation can be, but is not limited to, 15%, 25% or 30%. The low-temperature recrystallization annealing temperature can be, but is not limited to, 260°C, 320°C or 370°C, and the holding time can be, but is not limited to, 20 min, 70 min or 120 min. The cold deformation processing and low-temperature recrystallization annealing cycle number is 4-5 times.

[0037] In some preferred embodiments, the oxygen-free copper alloy strip has a thickness of 0.2-3 mm and a width of ≥600 mm.

[0038] The present application is further illustrated by the following specific examples and comparative examples, but it should be understood that these examples are merely used for more detailed illustration and should not be understood as limiting the present application in any form.

[0039] In the following examples and comparative examples, the raw materials are all acid-washed to remove the surface oxide layer, unless otherwise specified.

[0040] Example 1: 1. Melting: Weigh the raw materials according to the alloy composition ratio and place them in a vacuum melting furnace for melting. Melting temperature: 1210℃, furnace pressure ≤10. -3 Pa, after the metal raw material is melted, argon gas is introduced and the mixture is allowed to stand for 5 minutes; 2. Semi-continuous casting: Under argon protection, the alloy melt flows out from the overflow port of the vacuum melting furnace and is poured into the crystallizer. The alloy melt solidifies under indirect cooling by circulating water and is drawn out of the crystallizer to form an ingot. The casting temperature is 1200℃ and the casting speed is 80mm / min. 3. Hot rolling: The ingot is heated in a walking beam furnace at a temperature range of 1000℃ and a speed of 11℃ / min. The initial rolling temperature is 880℃ and the final rolling temperature is 760℃, with a total processing rate of 92%. After hot rolling, the ingot is cooled by argon air and milled. The specific operation method is not limited and any method known to those skilled in the art can be used. 4. Cold rolling: The hot-rolled sheet obtained in step 3 is subjected to cold deformation processing, with a deformation amount of 82%; 5. Recrystallization annealing: Under argon protection, the cold-rolled alloy strip is subjected to recrystallization annealing at a temperature of 620℃ and a holding time of 60min; 6. Small deformation + low temperature recrystallization annealing: Under argon protection, the "small deformation + low temperature recrystallization annealing" process is carried out repeatedly. The small deformation is cold deformation processing with a deformation amount of 20%. The low temperature recrystallization annealing temperature is 300℃, the holding time is 60min, and the number of cycles is 4. Example 2: 1. Melting: Weigh the raw materials according to the alloy composition ratio and place them in a vacuum melting furnace for melting. Melting temperature: 1200℃, furnace pressure ≤10. -3 Pa, after the metal raw material is melted, argon gas is introduced and the mixture is allowed to stand for 5 minutes; 2. Semi-continuous casting: Under argon protection, the alloy melt flows out from the overflow port of the vacuum melting furnace and is poured into the crystallizer. The alloy melt solidifies under indirect cooling by circulating water and is drawn out of the crystallizer to form an ingot. The casting temperature is 1150℃ and the casting speed is 75mm / min. 3. Hot rolling: The ingot is heated in a walking beam furnace at a temperature range of 1100℃ and a speed of 12℃ / min. The initial rolling temperature is 900℃ and the final rolling temperature is 830℃, with a total processing rate of 98%. After hot rolling, the ingot is cooled by argon air and milled. The specific operation method is not limited and any method known to those skilled in the art can be used. 4. Cold rolling: The hot-rolled sheet obtained in step 3 is subjected to cold deformation processing, with a deformation amount of 85%; 5. Recrystallization annealing: Under argon protection, the cold-rolled alloy strip is subjected to recrystallization annealing at a temperature of 650℃ for 30 minutes. 6. Small deformation + low temperature recrystallization annealing: under argon protection, a cyclic "small deformation + low temperature recrystallization annealing" process is carried out, wherein the small deformation is cold deformation processing, the deformation amount is 30%, the low temperature recrystallization annealing temperature is 370℃, the holding time is 20min, and the cycle number is 4 times.

[0041] Example 3: 1. Melting: according to the proportioning of alloy composition, raw materials are weighed and put into a vacuum melting furnace for melting, the melting temperature is 1230℃, the furnace pressure is ≤10 -3 Pa, after the metal raw materials are melted, argon is introduced and kept for 5min; 2. Semi-continuous casting: under argon protection, the alloy melt is flowed out from the overflow outlet of the vacuum melting furnace and poured into a crystallizer, the alloy melt is condensed under indirect cooling of circulating water, and the ingot is formed after being pulled out of the crystallizer, the casting temperature is 1220℃, and the casting speed is 85mm / min; 3. Hot rolling: the ingot is heated by using a step furnace, the temperature range is 850℃, the rate is 10~12℃ / min, the opening rolling temperature is 830℃, the final rolling temperature is 650℃, and the total processing rate is 90%, after the hot rolling is completed, argon air cooling and milling are carried out, the specific operation method is not limited, and methods well known to those skilled in the art can be used; 4. Cold rolling: the hot-rolled plate obtained in step 3 is subjected to cold deformation processing, and the deformation amount is 74%; 5. Recrystallization annealing: under argon protection, the cold-rolled alloy strip is subjected to recrystallization annealing, the annealing temperature is 600℃, and the holding time is 120min; 6. Small deformation + low temperature recrystallization annealing: under argon protection, a cyclic "small deformation + low temperature recrystallization annealing" process is carried out, wherein the small deformation is cold deformation processing, the deformation amount is 15%, the low temperature recrystallization annealing temperature is 260℃, the holding time is 120min, and the cycle number is 4 times.

[0042] Example 4: Compared with example 1, the difference lies in that the content of main micro-alloying elements is different, as shown in table 1, and the cycle number of the "small deformation + low temperature recrystallization annealing" process is 5 times.

[0043] Example 5: Compared with example 1, the difference lies in that the content of main micro-alloying elements is different, as shown in table 1.

[0044] Comparative example 1: The difference from example 2 is that Y / (La+Ce) > 0.6.

[0045] Comparative example 2: The difference from example 3 is that Y / (La+Ce) < 0.2.

[0046] Comparative Example 3: The difference from Example 1 is that no Ni element is added.

[0047] Comparative Example 4: The difference from Example 1 is that no Si element is added.

[0048] Comparative Example 5: The difference from Example 1 is that the Mg element is added too much.

[0049] Comparative Example 6: The difference from Example 1 is that the Te element is added too much.

[0050] Comparative Example 7: The difference from Example 5 is that the total amount of added elements is too much.

[0051] Comparative Example 8: The difference from Example 2 is that the Ni element is added too much.

[0052] Comparative Example 9: The difference from Example 4 is that the Si element is added too much.

[0053] Comparative Example 10: The difference from Example 4 is that the raw material is not subjected to pickling treatment.

[0054] Comparative Example 11: The difference from Example 4 is that the recrystallization temperature in Step 5 is high, being 550°C.

[0055] Comparative Example 12: The difference from Example 4 is that the Step 6 process of "small deformation + low-temperature recrystallization annealing" is performed once.

[0056] Comparative Example 13: The difference from Example 1 is that the Mg, Te, and La elements are not added in combination, the total amount of the three is the same, but no Te is added.

[0057] Comparative Example 14: The difference from Example 1 is that the Mg, Te, and La elements are not added in combination, the total amount of the three is the same, but no Mg is added.

[0058] Table 1 Alloy composition formula (wt. ppm) of Examples and Comparative Examples

[0059] Test Example 1 The ingot oxygen content of the oxygen-free copper provided in the examples and comparative examples, the thickness, conductivity, hardness, twin grain boundary ratio, average grain size and heat resistance of the finished product of the micro-alloyed oxygen-free copper were detected, wherein the heat resistance detection was the average grain size detection of the oxygen-free copper after high temperature heat treatment (800℃x90min) treatment (the oxygen-free copper is mainly applied to sintered ceramic copper-clad plate, and the grain is required not to grow significantly after high temperature treatment). The results are shown in Table 2.

[0060] Table 2 Alloy properties and microstructure of examples and comparative examples .

[0061] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the examples of the present application.

Claims

1. An oxygen-free copper alloy strip, characterized by, comprises, in mass percentage: Ni 20-100 ppm, Si 10-100 ppm, La and / or Ce 20-80 ppm, Y 10-30 ppm, and the balance being copper; 0.2≤mass percentage of Y / (mass percentage of La and Ce)≤0.6; The total mass percentage of the Ni, Si, La, Ce and Y is less than or equal to 300 ppm.

2. The oxygen-free copper alloy strip according to claim 1, characterized in that, Further comprising one or more of Te and Mg; The mass percentage of Te in the oxygen-free copper alloy strip is not more than 50 ppm; The mass percentage of Mg in the oxygen-free copper alloy strip is not more than 50 ppm; The total mass percentage of the Ni, Si, La, Ce, Y, Mg and Te is less than or equal to 300 ppm.

3. The method of producing the oxygen-free copper alloy strip as claimed in claim 1 or 2, characterized in that, comprises the following steps: The oxygen-free copper alloy strip is prepared by the following steps: batching according to mass percentage, then sequentially performing smelting, semi-continuous casting, hot rolling, cold rolling, recrystallization annealing, and cold deformation processing and low-temperature recrystallization annealing cycle treatment.

4. The production method according to claim 3, characterized by, The raw materials of the oxygen-free copper alloy strip comprise: electrolytic copper, pure nickel, nickel-silicon alloy, copper-magnesium alloy, copper-tellurium alloy, copper-lanthanum alloy, copper-yttrium alloy and copper-cerium alloy. The raw materials further comprise the step of pickling to remove the surface oxide layer and impurities of the raw materials before smelting.

5. The preparation method according to claim 3, characterized in that, The temperature of the smelting is 1200-1230℃. The temperature of the semi-continuous casting is 1150-1220℃, and the casting speed is 75-85 mm / min.

6. The preparation method according to claim 3, characterized in that, The opening rolling temperature of the hot rolling is 830-900℃. The final rolling temperature of the hot rolling is 650-830℃. The total processing rate of the hot rolling is 90%-98%.

7. The preparation method according to claim 6, characterized in that, The cast ingot obtained by semi-continuous casting is heated to 850-1100℃ before the hot rolling.

8. The preparation method according to claim 3, characterized in that, The deformation amount of the cold rolling is 74%-85%.

9. The preparation method according to claim 3, characterized in that, The recrystallization annealing is performed under a protective atmosphere. The annealing temperature of the recrystallization annealing is 600-650℃, and the holding time is 30-120 min.

10. The method of claim 3, wherein, The deformation amount of the cold deformation processing is 15%-30%. The temperature of the low-temperature recrystallization annealing is 260-370℃, and the holding time is 20-120 min. The cycle number of the cold deformation processing and low-temperature recrystallization annealing cycle treatment is 4-5.

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