TWI870073B - Copper plate with low anisotropy and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a manufacturing method of a copper plate with low anisotropy. The manufacturing method is to subject a high-purity copper blank to a heating process, rolling processes, and heat treatment processes under specific conditions, so as to change the grain size, recrystallization texture and rolling texture of the obtained copper plate. The in-plane anisotropies of the yield stress, tensile strength stress, and elongation of the copper plate obtained by the manufacturing method of the present invention in the three directions of 0°, 45° and 90° are all less than 5%.

Description

Low anisotropy copper plate and manufacturing method thereof

The present invention relates to a low anisotropic copper plate and a method for manufacturing the low anisotropic copper plate. The horizontal anisotropy of the yield strength, tensile strength and elongation of the low anisotropic copper plate of the present invention in the three directions of 0°, 45° and 90° is less than 5%.

Generally, cast, extruded and rolled copper sheets often have obvious anisotropy due to the large differences in mechanical properties (e.g., yield strength, tensile strength and elongation) in the three directions of 0°, 45° and 90°, and therefore cannot be formed smoothly.

Currently, a copper plate made by continuous casting is known. After the high-purity copper raw material is heated, it is directly cast into a cylindrical copper ingot, then sliced into copper plates, and then processed into copper charge liners. However, the grain size of the copper plate obtained by this method is greater than 5000μm, resulting in a considerable difference in mechanical properties in the three directions of 0°, 45° and 90°. For example, the horizontal anisotropy of tensile strength and the horizontal anisotropy of elongation are both greater than 10%. Therefore, the copper plate obtained by this method cannot be formed smoothly, and produces phenomena such as orange peel and cracking.

It is also known that a copper plate is made by forging, in which a copper ingot is forged at a high temperature into a cylindrical copper ingot, which is then sliced into a copper plate and processed into a copper charge liner. However, the size of the copper plate obtained by this method is about 400μm and the grain size distribution is uneven, resulting in a large difference in elongation in the three directions of 0°, 45°, and 90°. For example, the horizontal anisotropy of its elongation is as high as 12%. When this copper plate is formed, it cannot be smoothly formed into a symmetrical shape due to the large difference in elongation in the three directions, and lugs or asymmetric products will be generated.

Therefore, it is urgent to provide a method for manufacturing low anisotropic copper plates to solve the above problems.

One aspect of the present invention is to provide a low anisotropic copper plate, wherein the grain size of the copper plate is less than 70 μm, and has a specific ratio of (100) [001] recrystallized aggregate structure and (110) [112] and (112) [111] rolled aggregate structure. The horizontal anisotropy of various mechanical properties of the copper plate in the three directions of 0°, 45° and 90° is less than 5%, so the low anisotropic copper plate of the present invention can avoid the occurrence of orange peel, cracks and bulges, and can be formed smoothly.

At least one embodiment of the present invention provides a method for manufacturing a low anisotropic copper plate, comprising the following steps. A copper blank is provided. The copper blank is heated. After the heating step, the copper blank is hot-rolled to obtain a hot-rolled copper plate. The hot-rolled copper plate is cold-rolled to obtain a cold-rolled copper plate. The cold-rolled copper plate is annealed to obtain an annealed copper plate. The annealed copper plate is water-cooled to obtain a low anisotropic copper plate. Among them, in the low anisotropic copper plate, the horizontal anisotropy of yield strength is less than 5%, the horizontal anisotropy of tensile strength is less than 5%, and the horizontal anisotropy of elongation is less than 5%.

In at least one embodiment of the present invention, the purity of the copper blank is 99.9% to 99.99%.

In at least one embodiment of the present invention, the heating temperature of the above heating step is 550°C to 650°C. The heating time of the above heating step is 30 minutes to 2 hours.

In at least one embodiment of the present invention, the hot rolling reduction in each pass of the hot rolling step is 5% to 20%. The finishing temperature of the hot rolling step is 500℃ to 550℃.

In at least one embodiment of the present invention, the cold rolling reduction in each pass of the cold rolling step is 5% to 20%.

In at least one embodiment of the present invention, the total cold rolling reduction in the above-mentioned cold rolling step is 50% to 60%.

In at least one embodiment of the present invention, the annealing temperature of the above annealing step is 300°C to 400°C.

In at least one embodiment of the present invention, the annealing time of the above annealing step is 30 minutes to 2 hours.

In at least one embodiment of the present invention, the water cooling time in the water cooling step of the annealed copper plate is within 2 minutes, and the temperature is reduced to room temperature within 2 minutes.

In at least one embodiment of the present invention, the low anisotropic copper plate is manufactured by the above-mentioned manufacturing method, wherein in the low anisotropic copper plate, the horizontal anisotropy of the yield strength is less than 5%, the horizontal anisotropy of the tensile strength is less than 5%, and the horizontal anisotropy of the elongation is less than 5%.

In order to make the above and other purposes, features, advantages and embodiments of the present invention more clearly understood, the detailed description of the attached drawings is as follows.

Figure 1 is a scanning electron microscope image of a low anisotropic copper plate according to an experimental example of the present invention.

The manufacture and use of embodiments of the present invention are discussed in detail below. However, it is understood that the embodiments provide many applicable inventive concepts that can be implemented in a variety of specific contexts. The specific embodiments discussed are for illustration only and are not intended to limit the scope of the present invention.

In this article, the range expressed by "a value to another value" is a summary expression method to avoid listing all the values in the range one by one in the specification. Therefore, the description of a specific numerical range covers any numerical value within the numerical range and the smaller numerical range defined by any numerical value within the numerical range, just as if the arbitrary numerical value and the smaller numerical range were written in the specification. The terms "about", "approximately" or "approximately" used in this article generally refer to the error or range of the numerical value within about 20%, preferably within about 10%, and more preferably within about 5%.

， 其中，X_max代表三個方向的力學性能的最大值，X_mid代表三 個方向的力學性能的中間值，X_min代表三個方向的力學性能的最小值。上述「三個方向」為0°、45°和90°方向。上述「力學性能」包含降伏強度、拉伸強度以及伸長率。 It should be noted that the term "anisotropy" in this article refers to "in-plane anisotropy (IPA)", which is used to quantify the anisotropy of the sheet material. The calculation formula of IPA is

, where X _max represents the maximum value of the mechanical properties in the three directions, X _mid represents the middle value of the mechanical properties in the three directions, and X _min represents the minimum value of the mechanical properties in the three directions. The above-mentioned "three directions" are 0°, 45° and 90° directions. The above-mentioned "mechanical properties" include yield strength, tensile strength and elongation.

The definitions of the above 0°, 45° and 90° directions are well known to those with common knowledge. A brief explanation is as follows: the 0°, 45° and 90° directions are all parallel to the top surface of the plate, and the 0° direction is used as the starting direction. Rotating it 45° and 90° clockwise will respectively give the 45° and 90° directions.

Some embodiments of the present invention provide a method for manufacturing a low anisotropic copper plate. The manufacturing method includes heating and hot rolling a copper blank to obtain a hot rolled copper plate. The hot rolled copper plate is water cooled to obtain a water cooled copper plate. The water cooled copper plate is cold rolled to obtain a cold rolled copper plate. The cold rolled copper plate is annealed to obtain an annealed copper plate. The annealed copper plate is water cooled to obtain the low anisotropic copper plate of the present invention.

In some embodiments, the grain size of the low anisotropic copper plate is less than 70 μm. When the grain size of the copper plate is greater than 70 μm, it will affect the (100)[001] recrystallization structure and the (110)[112] and (112)[111] rolled structures of the copper plate, making the horizontal anisotropy of the various mechanical properties of the copper plate in the three directions of 0°, 45° and 90° greater than 5%, so the copper plate will produce orange peel, cracks and bulges during the forming process.

In some embodiments, since the low anisotropic copper plate of the present invention has both (100)[001] recrystallized aggregate structure and (110)[112] and (112)[111] rolled aggregate structures, the horizontal anisotropy of the yield strength, tensile strength and elongation of the low anisotropic copper plate in the three directions of 0°, 45° and 90° is less than 5%. When the horizontal anisotropy of various mechanical properties is greater than 5%, the copper plate cannot be formed smoothly, and the copper plate will produce orange peel, cracks and lugs during the forming process, which is not conducive to subsequent applications.

In some embodiments, the purity of the copper blank is 99.9% to 99.99%. When the purity of the copper blank is within the above range, the grain size of the copper plate formed subsequently can be less than 70μm, and the horizontal anisotropy of various mechanical properties of the copper plate can be less than 5%.

In some embodiments, the heating temperature of the heating step is 550°C to 650°C. In some embodiments, the heating time of the heating step is 30 minutes to 3 hours. When the heating temperature and the heating time are within the above range, it is beneficial to uniformly heat the copper billet and facilitate the subsequent rolling step.

In some embodiments, the hot rolling reduction of each pass in the hot rolling step is 5% to 20%. In some embodiments, the total hot rolling reduction in the hot rolling step is 50% to 90%. In some embodiments, the finishing temperature of the hot rolling step is 500°C to 550°C. Since the hot rolling step needs to achieve a sufficient total reduction and maintain a specific finishing temperature, it is possible to ensure that the copper plate has uniform and fine grains. Therefore, when the hot rolling reduction per pass, the total hot rolling reduction and the finishing temperature are within the above range, the grain size of the copper plate to be formed subsequently can be less than 70μm, and the horizontal anisotropy of various mechanical properties of the copper plate can be less than 5%.

In some embodiments, the water cooling time of the hot-rolled copper plate in the water cooling step is 30 seconds to 20 minutes, and the plate is water-cooled to room temperature. When the water cooling time is within the above range, the copper plate can be prevented from being subjected to high temperature and grain growth, thereby ensuring the fine grain size of the copper plate, thereby strengthening the strength of the copper plate. Therefore, the grain size of the copper plate formed subsequently can be made less than 70 μm, and the horizontal anisotropy of various mechanical properties of the copper plate can be less than 5%.

In some embodiments, the cold rolling reduction in each pass of the cold rolling step is 5% to 20%. In some embodiments, the total cold rolling reduction in the cold rolling step is 50% to 60%. Since the total cold rolling reduction must be more than 50% to ensure the formation of a specific aggregate structure and reduce the anisotropy of the copper plate. Therefore, when the cold rolling reduction in each pass and the total cold rolling reduction are between the above ranges, the grain size of the copper plate formed subsequently can be less than 70μm, and the horizontal anisotropy of various mechanical properties of the copper plate can be less than 5%.

In some embodiments, the annealing temperature of the annealing step is 300°C to 400°C. In some embodiments, the annealing time of the annealing step is 30 minutes to 2 hours. In the annealing step, the copper plate undergoes recrystallization, which promotes the growth of grains. Therefore, when the annealing temperature and annealing time are within the above range, the grain size of the copper plate formed subsequently can be less than 70μm, and the horizontal anisotropy of various mechanical properties of the copper plate is less than 5%.

In some embodiments, the water cooling time in the water cooling step of the annealed copper plate is within 2 minutes, and the temperature is cooled to room temperature within 2 minutes to obtain a low anisotropy copper plate. Water cooling after the annealing step can prevent the copper plate from growing grains due to high temperature, which is beneficial to grain refinement. Therefore, when the water cooling time in the water cooling step is within the above range, the grain size of the subsequently formed copper plate can be less than 70μm, and the horizontal anisotropy of various mechanical properties of the copper plate can be less than 5%.

The following experimental examples are used to illustrate the application of the present invention, but they are not used to limit the present invention. Anyone familiar with this art can make various changes and modifications without departing from the spirit and scope of the present invention.

Experimental example

First, a copper blank with a purity of 99.99% is placed in a high-temperature furnace and heated at 650°C for 3 hours. Then, the heated copper blank is subjected to a hot rolling step, wherein the total hot rolling reduction of the hot rolling step is 80%, and the final rolling temperature is controlled below 550°C to obtain a hot rolled copper plate. Next, the hot rolled copper plate is subjected to a water cooling step, and the hot rolled copper plate is cooled to room temperature within 2 minutes to obtain a water-cooled copper plate. Then, the water-cooled copper plate is subjected to a cold rolling step, wherein the total cold rolling reduction is 55%, to obtain a cold rolled copper plate. After obtaining the cold-rolled copper plate, a water cooling step is performed again. Then, the cold-rolled copper plate is annealed, and the cold-rolled copper plate is heat treated at 400°C for 1 hour to obtain an annealed copper plate. Then, the annealed copper plate is water-cooled to obtain the low anisotropy copper plate of the present invention.

Please refer to Figure 1 for the metallographic structure of the copper plate produced in the experimental example. The grain size of the copper plate produced in the experimental example was measured by the following evaluation methods, as well as the yield stress (YS), tensile strength (TS), elongation (EL) and the above-mentioned IPA in the three directions of 0°, 45° and 90°. The results are shown in Table 1.

Comparison example

First, a copper blank with a purity of 99.99% is placed in a high-temperature furnace and heated at 950°C for 3 hours. Then, the heated copper blank is subjected to a hot rolling step, wherein the total hot rolling reduction of the hot rolling step is 90%, and the finishing temperature is controlled below 800°C to obtain a hot rolled copper plate. Next, the hot rolled copper plate is subjected to an annealing step and heat treated at 700°C for 1 hour to obtain an annealed copper plate. Then, the annealed copper plate is subjected to a water cooling step to obtain a copper plate.

The copper plate produced in the comparative example was evaluated using the following evaluation methods to measure the grain size of the copper plate, as well as the yield strength, tensile strength, elongation and the above-mentioned IPA in the three directions of 0°, 45° and 90°. The results are shown in Table 1.

Evaluation method 1. Grain size

The grain size of the present invention is measured by scanning electron microscope images, and the average grain size obtained by the diagonal, horizontal and vertical line measurement method of standard method ASTM E8 is used as the evaluation result. Table 1 shows that the grain size of the experimental example is less than 70μm, and its scanning electron microscope image is shown in Figure 1, where the grain distribution in Figure 1 is uniform. The grain size of the comparative example is 350μm to 400μm.

2. Yield strength (YS)

The yield strength referred to herein in the present invention is tested according to the standard method ASTM E8 to measure the yield strength of the copper plates of the experimental examples and comparative examples in three directions of 0°, 45° and 90°, and the unit is MPa. Table 1 shows that the yield strength of the copper plates of the experimental examples in each direction is about 68MPa, while the yield strength of the copper plates of the comparative examples in each direction ranges from about 79MPa to about 101MPa.

3. Tensile strength (TS)

The tensile strength referred to herein in the present invention is tested according to the standard method ASTM E8 to measure the tensile strength of the copper plates of the experimental examples and comparative examples in three directions of 0°, 45° and 90°, and the unit is MPa. Table 1 shows that the tensile strength of the copper plates of the experimental examples in each direction is about 224MPa, while the yield strength of the copper plates of the comparative examples in each direction ranges from about 200MPa to about 203MPa.

4. Elongation

The elongation referred to herein in the present invention is tested according to the standard method ASTM E8 to measure the elongation of the copper plates of the experimental examples and the comparative examples in three directions of 0°, 45° and 90°. Table 1 shows that the elongation of the copper plates of the experimental examples in each direction ranges from about 57% to about 61%, while the elongation of the copper plates of the comparative examples in each direction ranges from about 51% to about 57%.

5.IPA

The above IPA calculation formula is used to calculate the above IPA of yield strength, tensile strength and elongation. The IPA of various mechanical properties of the experimental example is less than 5%, while the IPA of yield strength and elongation of the comparative example are greater than 5%.

By analyzing the structure of the copper plate obtained in the above experimental example, it can be seen that the (100)[001] recrystallized structure accounts for 5.8%, the (110)[112] rolled structure accounts for 11.6%, and the (112)[111] rolled structure accounts for 8.4%.

The copper plate obtained in the above comparative example has relatively coarse grains (350μm to 400μm), and because the copper plate has completed recrystallization, the recrystallized aggregate structure strength is high, and the rolled aggregate structure strength is relatively low, resulting in a large anisotropy of the copper plate. Therefore, the copper plate has a relatively high yield strength IPA and elongation IPA in the three directions of 0°, 45°, and 90°.

The grain size of the low anisotropic copper plate of the present invention is less than 70μm, and has a specific ratio of (100)[001] recrystallized aggregate structure and (110)[112] and (112)[111] rolled aggregate structure. Secondly, the horizontal anisotropy of various mechanical properties of the copper plate in the three directions of 0°, 45° and 90° is less than 5%, so the low anisotropic copper plate of the present invention can avoid the occurrence of orange peel, cracks and bulges during forming, so it can be formed smoothly.

It is understandable that although the present invention uses a specific manufacturing method and a specific evaluation method as examples to illustrate the manufacturing method of the low anisotropic copper plate of the present invention, anyone with common knowledge in the technical field to which the present invention belongs can know that the present invention is not limited to this. Without departing from the spirit and scope of the present invention, the present invention can also be carried out using other manufacturing methods or other evaluation methods.

Although the present invention has been disclosed in the form of implementation as above, it is not intended to limit the present invention. Anyone with common knowledge in the technical field to which the present invention belongs can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of the patent application attached hereto.

Claims (8)

A method for manufacturing a low anisotropic copper plate comprises: providing a copper blank, wherein the purity of the copper blank is 99.9% to 99.99%; performing a heating step on the copper blank; after the heating step, performing a hot rolling step on the copper blank to obtain a hot rolled copper plate, wherein a total heat reduction in the hot rolling step is 50% to 90%, and a finishing temperature in the hot rolling step is 500°C to 550°C; performing a cold rolling step on the hot rolled copper plate to obtain a cold rolled copper plate, wherein each of the cold rolling steps is 100°C to 150°C. The cold rolling reduction in one pass is 5% to 20%, and the total cold rolling reduction in the cold rolling step is more than 50%; the cold rolled copper plate is subjected to an annealing step to obtain an annealed copper plate; the annealed copper plate is subjected to a water cooling step to obtain the low anisotropy copper plate, wherein a grain size of the low anisotropy copper plate is less than 70 μm, wherein in the low anisotropy copper plate, the horizontal anisotropy of the yield strength is less than 5%, the horizontal anisotropy of the tensile strength is less than 5%, and the horizontal anisotropy of the elongation is less than 5%. The method for manufacturing a low anisotropic copper plate as described in claim 1, wherein: a heating temperature of the heating step is 550°C to 650°C; and a heating time of the heating step is 30 minutes to 3 hours. A method for manufacturing a low anisotropic copper plate as described in claim 1, wherein: The hot rolling reduction in each pass of the hot rolling step is 5% to 20%. The method for manufacturing a low anisotropic copper plate as described in claim 1, wherein the total cold rolling reduction in the cold rolling step is 50% to 60%. The method for manufacturing a low anisotropic copper plate as described in claim 1, wherein an annealing temperature of the annealing step is 300°C to 400°C. The method for manufacturing a low anisotropic copper plate as described in claim 1, wherein the annealing time of the annealing step is 30 minutes to 2 hours. The method for manufacturing a low anisotropic copper plate as described in claim 1, wherein the water cooling time of the annealed copper plate in the water cooling step is within 2 minutes, and the temperature is lowered to room temperature within 2 minutes. A low anisotropic copper plate is produced by the method for producing a low anisotropic copper plate as described in any one of claims 1 to 7, wherein in the low anisotropic copper plate, the horizontal anisotropy of the yield strength is less than 5%, the horizontal anisotropy of the tensile strength is less than 5%, the horizontal anisotropy of the elongation is less than 5%, the (100)[001] recrystallized aggregate structure accounts for 5.8%, the (110)[112] rolled aggregate structure accounts for 11.6%, and the (112)[111] rolled aggregate structure accounts for 8.4%.