CN109694973B

CN109694973B - Electronic product shell material and manufacturing method thereof

Info

Publication number: CN109694973B
Application number: CN201811483590.2A
Authority: CN
Inventors: 薛烽; 邱馨婷; 陶卫建; 魏明震
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2018-12-05
Filing date: 2018-12-05
Publication date: 2020-10-16
Anticipated expiration: 2038-12-05
Also published as: CN109694973A

Abstract

The invention discloses a shell material for an electronic product and a manufacturing method thereof. The material consists of 0.5 to 4 weight percent of Mg, 5 to 9 weight percent of Zn, 0.1 to 2 weight percent of Cu, and the balance of Al and inevitable impurities, wherein the content of impurity elements is less than 0.1 percent. The manufacturing method comprises the following steps: preheating the furnace temperature, placing pure Al in a smelting furnace, heating to 790-830 ℃, heating to 1100-1200 ℃ after the pure Al is melted, adding pure Zn and pure Cu, cooling to 650-700 ℃ after the pure Al is melted, adding pure Mg, heating to 730-750 ℃ after the pure Al is melted, adding hexachloroethane for refining and deslagging, standing for 15-30 min, and then pouring. After the ingot casting is homogenized, the ingot casting is extruded to form a section material with crystal grains in an isometric crystal form, the crystal grain orientation is isotropic, and a 101 texture is formed in the [010] direction. The section is cold rolled to enable the aluminum alloy to generate internal stress and serve as a driving force for subsequent recrystallization, and then solid solution and aging treatment are carried out, so that the coarse crystal layer can be recovered and recrystallized into fine crystal grains under the condition that the crystal grains are in an isometric crystal state.

Description

Electronic product shell material and manufacturing method thereof

Technical Field

The invention relates to an electronic product shell material and a manufacturing method thereof.

Background

With the rapid development of communication and digital technologies, portable electronic products (such as mobile phones, mobile chargers, etc.) are upgraded and updated several times in a few decades of time, and become an epoch epitome of technological progress. The shell is not only a powerful protective umbrella for the portable electronic product, but also can effectively reduce the invasion of dust, reduce the damage caused by accidental falling, prolong the service life of the portable electronic product, and more importantly, improve the product experience of a user. Therefore, the material for manufacturing the portable electronic product shell is required to have the characteristics of high strength, good heat resistance and thermal conductivity, electromagnetic shielding property, stable size, good appearance and the like, and the formed product is developed towards light weight and thin wall so as to achieve the effects of protection, heat dissipation and beauty, which also puts higher requirements on the forming process.

Materials commonly used to make portable electronic housings fall into the following 5 categories: engineering plastics, metal materials, composite materials, glass materials, wood, ceramics and other materials. With the improvement of science and technology and the aesthetic sense of people, the shell of the portable electronic product is more and more made of metal. The electronic product with the aluminum alloy shell has strong metal texture, can be oxidized into various colors in the natural world, is popular with consumers, and represents the direction of high-end electronic products.

Aluminum-magnesium alloy, i.e., aluminum alloy with Mg as a main additive element, is commonly used for manufacturing the housing. In 2002, the second generation of IPod originally used 5 series aluminum alloy as the outer shell, but the series aluminum alloy was not scratch resistant. From apple 5, apple company began to select 6063 aluminum alloy as the most suitable alloy for deformation processing, and the strength and wear resistance were improved. In 2014, apple 6 still continues to use 6063 aluminum alloy, but with the increase of the screen size of the mobile phone and the reduction of the thickness of the mobile phone shell, the series of aluminum alloys cannot meet the requirement of strength, so that the mobile phone is bent frequently.

In 2015, apple 6s first started using its autonomously developed 7003 aluminum alloy as a handset case, improving strength and hardness, but its global supply was only two and the yield was also low. According to earlier researches, the appearance of the existing 7-series aluminum alloy after anodic oxidation does not meet the requirements when the existing aluminum alloy is used for manufacturing a shell of a portable electronic product, and a long-strip-shaped filamentous non-reflective tissue exists, so that the surface is non-uniform in reflection. How to obtain the novel high-strength 7-series aluminum alloy for the portable electronic product shell, which meets the appearance requirement and the mechanical property requirement after anodic oxidation, through the design of the component design and the preparation method is the problem to be solved by the patent of the invention. Meanwhile, the aluminum alloy used for manufacturing the portable electronic product housing is an extruded product, and a coarse-grained layer is usually present on the outermost layer, as shown in fig. 2. The invention reduces coarse crystal layers and reduces cost through a proper processing mode.

Disclosure of Invention

The invention provides an electronic product shell material capable of improving mechanical property and anodic oxidation property and reducing processing waste and a manufacturing method thereof.

The technical scheme for realizing the aim of the invention is as follows:

the electronic product shell material consists of Mg, Zn, Cu, Al and inevitable impurities, wherein the Mg accounts for 0.5-4 wt%, the Zn accounts for 5-9 wt%, the Cu accounts for 0.1-2 wt%, and the balance is the Al and the inevitable impurities, wherein the content of impurity elements is less than 0.1%.

The invention relates to a manufacturing method for an electronic product shell material, which comprises the following steps:

1) preheating the furnace temperature, placing pure Al in a smelting furnace, heating to 790-830 ℃, heating to 1100-1200 ℃ after the pure Al is molten, then adding pure Zn and pure Cu, cooling to 650-700 ℃ after the raw materials are molten for 2-3 min, adding pure Mg, pressing the pure Mg into the bottom of the melt for 2-3 min until the pure Mg is molten, heating to 730-750 ℃ again, simultaneously adding a refining agent hexachloroethane for refining and deslagging, standing for 15-30 min, and then pouring;

2) after the cast ingot is subjected to homogenization treatment of keeping the temperature of 530-570 ℃ for 5 hours, the cast ingot is extruded to form a section with 101 texture, the crystal grains are in an isometric crystal form, the crystal grain orientation is isotropic, and the strength of the section is more than 1.5 in the [010] direction.

Further, cold rolling is carried out on the section by using the reduction of 20-40%, so that internal stress is generated in the aluminum alloy and is used as a driving force for subsequent recrystallization, then solid solution treatment of 450-500 ℃/1h is carried out, 2-stage aging treatment of 100-110 ℃/6h + 150-160 ℃/6h is carried out immediately after quenching, and the coarse crystal layer can be subjected to recovery recrystallization and is converted into fine crystal grains under the condition that the crystal grains are kept in an isometric crystal state.

Compared with the prior art, the invention has the following advantages:

(1) all elements of the formula of the invention are elements which discharge and hinder recrystallization, an isometric crystal structure is formed after smelting and extrusion, simultaneously a 101 texture with the strength exceeding 1.5 exists in the [010] direction (refer to figures 3 and 4), and because the crystal grain orientation is isotropic and a stronger 101 texture exists in the [010] direction, the corrosion resistance of the crystal grains is similar, so that the corrosion is uniform during anodic oxidation, and the better appearance is obtained after anodic oxidation. Zn, Mg and Cu elements are simultaneously used as alloy elements to be added, and are configured according to the specific proportion range in the invention, and the prepared shell material can simultaneously realize high strength and good comprehensive performance after anodic oxidation. The higher Zn/Mg ratio is beneficial to improving the strength of the alloy, and the addition of the Cu element with higher content is beneficial to improving the solid solution strength and the mechanical property.

(2) The outermost layer of the extruded section or the electronic product shell has a coarse crystal layer which usually needs to be machined and cut off, thus causing processing waste. The single rolling or solution treatment can not solve the problem of a coarse crystal layer, the cold rolling, solution treatment and aging treatment are combined to solve the problem of the coarse crystal layer, the cold rolling with the reduction of 20-40% is firstly carried out on the section, so that the coarse crystal layer generates internal stress firstly to provide a driving force for recrystallization, then the solution treatment at 450-500 ℃/1h is carried out, 2-stage aging treatment at 100-110 ℃/6h + 150-160 ℃/6h is immediately carried out after quenching, recovery recrystallization is completed, and the coarse crystal layer is converted into fine isometric crystal, so that the processing waste is reduced, and the cost is reduced. Meanwhile, the crystal grains still keep the state of isometric crystals, and the good appearance is obtained after anodic oxidation.

Drawings

FIG. 1 is a process flow diagram for reducing the coarse crystalline layer of the outermost aluminum alloy layer of an extruded article.

FIG. 2 shows the coarse crystal layer of the outermost layer of the aluminum alloy of the extruded article.

FIG. 3 is a grain oriented drawing of the aluminum alloy of example 1.

FIG. 4 is a weave pattern in the [010] direction in example 1.

Fig. 5 is a gold phase diagram of example 1.

Fig. 6 is a golden phase diagram of example 2.

Fig. 7 is an example 3 golden phase diagram.

Fig. 8 is an example 4 golden phase diagram.

Detailed Description

1) preheating the furnace temperature, namely placing pure Al in a smelting furnace and heating to 790-830 ℃ (in the embodiment, placing pure Al in the smelting furnace and heating to 800 ℃), after the pure Al is molten, heating to 1100-1200 ℃, then adding pure Zn and pure Cu, after the raw materials are molten, cooling to 650-700 ℃ for 2-3 min, adding pure Mg, pressing the pure Mg into the bottom of the melt for 2-3 min until the pure Mg is molten, heating to 730-750 ℃ again, simultaneously adding a refining agent for refining and deslagging, and after standing for 15-30 min, pouring, wherein the embodiment of the refining agent can be hexachloroethane;

In the embodiment, the profile is subjected to cold rolling by using the reduction of 20-40% so that internal stress is generated in the aluminum alloy and is used as a driving force for subsequent recrystallization, then solid solution treatment is performed at 450-500 ℃/1h, 2-stage aging treatment of 100-110 ℃/6h + 150-160 ℃/6h is performed immediately after quenching, and the coarse crystal layer can be subjected to recovery recrystallization and converted into fine crystal grains under the condition of keeping the crystal grains in an isometric crystal state.

The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary in nature and is not intended to limit the scope of the invention or its application.

In one embodiment, as shown in table 1, an electronic product casing material comprises, by weight, 0.5% to 4% of Mg, 5% to 9% of Zn, 0.1% to 2% of Cu, and the balance Al and inevitable impurities of Si, Fe, and the like, wherein the content of impurity elements is less than 0.1%.

TABLE 1

Mg	0.5％～4％
		Zn	5％～9％
Cu	0.1％～2％
		Other total number	0.1％
Al	Balance of

In one embodiment, a method for manufacturing an electronic product housing material comprises the following steps: preheating the furnace temperature, placing pure Al in a smelting furnace, heating to 790-830 ℃, preferably to 800 ℃, heating to 1100-1200 ℃ after the pure Al is melted, then adding pure Zn and pure Cu, cooling to 650-700 ℃ after the raw materials are melted, adding pure Mg, pressing the pure Mg into the bottom of the melt for 2-3 minutes until the pure Mg is melted, heating to 730-750 ℃ again, adding a refining agent for refining and deslagging, standing for 15-30 minutes, and then pouring. And (3) carrying out homogenization treatment on the cast ingot at 530-570 ℃ for 5 hours, and extruding the cast ingot into a section with the required specification. In order to reduce a coarse grain layer of an aluminum alloy of an extruded product, the section is subjected to cold rolling with the reduction of 20-40%, solid solution treatment is performed at the speed of 450-500 ℃/1h, and then the section is quenched and then subjected to aging treatment at the speed of 100-110 ℃/6h + 150-160 ℃/6 h.

A material for electronic product shell and its making method, 4 examples are provided below.

Example 1

Preheating the furnace temperature, placing pure Al in a smelting furnace, heating to 800 ℃, heating to 1100 ℃ after the pure Al is molten, then adding pure Zn and pure Cu, heating for 3 minutes after the raw materials are molten, then cooling to 700 ℃, adding pure Mg, pressing the pure Mg into the bottom of the melt for 3 minutes until the pure Mg is molten, heating to 750 ℃ again, adding a refining agent hexachloroethane for refining and deslagging, standing for 30 minutes, and then pouring. And (5) uniformly casting the ingot at 550 ℃/5h, and extruding the ingot into a section with the required specification. The section is rolled with the rolling reduction of 30 percent, and is subjected to solution treatment at 500 ℃/1h, and then the section is quenched and is subjected to aging treatment at 100 ℃/6h +150 ℃/6 h. According to the weight percentage, the added pure Zn is 6 percent, the added pure Cu is 0.1 percent, and the added pure Mg is 1.5 percent.

Example 2

Preheating the furnace temperature, placing pure Al in a smelting furnace, heating to 800 ℃, heating to 1100 ℃ after the pure Al is molten, then adding pure Zn and pure Cu, heating to 3 minutes after the raw materials are molten, then cooling to 700 ℃, adding pure Mg, pressing the pure Mg into the bottom of the melt for 3 minutes until the pure Mg is molten, heating to 750 ℃ again, adding a refining agent hexachloroethane for refining and deslagging, standing for 20 minutes, and then pouring. And (5) uniformly casting the ingot at 550 ℃/5h, and extruding the ingot into a section with the required specification. The section is rolled with the rolling reduction of 20 percent, and is subjected to solution treatment at 500 ℃/1h, and then the section is quenched and is subjected to aging treatment at 100 ℃/6h +150 ℃/6 h. According to the weight percentage, the added pure Zn is 5.2 percent, the added pure Cu is 0.2 percent, and the added pure Mg is 1.4 percent.

Example 3

Preheating the furnace temperature, placing pure Al in a smelting furnace, heating to 800 ℃, heating to 1100 ℃ after the pure Al is molten, then adding pure Zn and pure Cu, heating for 3 minutes after the raw materials are molten, then cooling to 700 ℃, adding pure Mg, pressing the pure Mg into the bottom of the melt for 3 minutes until the pure Mg is molten, heating to 750 ℃ again, adding a refining agent hexachloroethane for refining and deslagging, standing for 40 minutes, and then pouring. And (5) uniformly casting the ingot at 550 ℃/5h, and extruding the ingot into a section with the required specification. The section is rolled with the rolling reduction of 30 percent, and is subjected to solution treatment at 500 ℃/1h, and then the section is quenched and is subjected to aging treatment at 100 ℃/6h +150 ℃/6 h. According to the weight percentage, the added pure Zn is 8 percent, the added pure Cu is 1.5 percent, and the added pure Mg is 3 percent.

Example 4

Preheating the furnace temperature, placing pure Al in a smelting furnace, heating to 800 ℃, heating to 1100 ℃ after the pure Al is molten, then adding pure Zn and pure Cu, heating for 3 minutes after the raw materials are molten, then cooling to 700 ℃, adding pure Mg, pressing the pure Mg into the bottom of the melt for 3 minutes until the pure Mg is molten, heating to 750 ℃ again, adding a refining agent hexachloroethane for refining and deslagging, standing for 20 minutes, and then pouring. The cast ingot is extruded into a section bar with the required specification after being evenly processed at 550 ℃/5h, and then the aging treatment is carried out at 100 ℃/6h +150 ℃/6 h. According to the weight percentage, the added pure Zn is 8 percent, the added pure Cu is 1.5 percent, and the added pure Mg is 3 percent.

The properties of the Al-Zn-Mg-Cu alloys prepared in examples 1 to 4 are shown in Table 2.

TABLE 2

	Example 1	Example 2	Example 3	Example 4
					Mg	1.5	1.4	3	3
Zn	6	5.2	8	8
					Cu	0.1	0.2	1.5	1.5
Anodizable oxidizability	Is preferably used	Is preferably used	Is preferably used	Is preferably used
					hardness/HV	150	143	181	165
Tensile strength/MPa	458	441	499	487

As can be seen from Table 2, the material for the electronic product housing of the present invention can obtain a good anodized high quality appearance and a high mechanical property requirement by controlling the alloy composition and the processing technology. Meanwhile, the strength of the alloy can be improved by properly increasing the content of the alloy elements.

From the EBSD results of example 1 in fig. 3 and 4, it can be seen that the grain distribution of the novel 7-series aluminum alloy is uniform, and a stronger 101 texture exists in the [010] direction, which may be related to uniform corrosion resistance, so that the subsequent anodization effect is good, and the EBSD results of examples 2-4 are the same as those of example 1.

As can be seen from fig. 5 to 8, in examples 1 to 3, the outermost coarse crystal layer was effectively removed due to the processing technique of the rolling heat treatment, while in example 4, the outermost coarse crystal layer still existed due to the absence of the rolling heat treatment, which illustrates that the outermost coarse crystal layer could be effectively removed by the processing technique of the present invention.

In conclusion, the invention realizes the combination of higher mechanical property, high hardness and anodic oxidation effect by adding reasonably optimized alloy components, reducing trace elements and controlling the process, and is an ideal material for manufacturing electronic product appearance parts with higher requirements on strength and anodic oxidation effect. Meanwhile, the relationship between the crystal grain orientation of the equiaxed crystals and the effect after anodic oxidation was observed by EBSD. Finally, the processing technology of proper rolling, solution treatment and aging is adopted, so that the coarse crystal layer at the outermost layer of the aluminum alloy of the extruded product is subjected to recovery recrystallization, and the cost is reduced. At the same time. The crystal grains are still kept in the form of isometric crystals, and the appearance is excellent after anodic oxidation.

The above is only a specific application example of the present invention, and the protection scope of the present invention is not limited in any way. All technical solutions formed by using equivalent transformations or equivalent replacements fall within the protection scope of the present invention.

Claims

1. A manufacturing method of an electronic product shell material is characterized by comprising the following steps:

1) preheating the furnace temperature, namely placing pure Al in a smelting furnace, heating to 790-830 ℃, heating to 1100-1200 ℃ after the pure Al is molten, then adding pure Zn and pure Cu, cooling to 650-700 ℃ after the raw materials are molten for 2-3 min, adding pure Mg, pressing the pure Mg into the bottom of the melt for 2-3 min until the pure Mg is molten, heating to 730-750 ℃ again, simultaneously adding a refining agent for refining and deslagging, standing for 15-30 min, and then pouring;

2) after the cast ingot is subjected to homogenization treatment of keeping the temperature at 530-570 ℃ for 5 hours, the cast ingot is extruded to form a section bar with crystal grains in an isometric crystal form, the crystal grain orientation is isotropic, and the 101-texture with the strength exceeding 1.5 is formed in the [010] direction;

the method comprises the steps of cold rolling the section by using the reduction of 20-40%, enabling internal stress to be generated inside the aluminum alloy and used as a driving force for subsequent recrystallization, then carrying out solid solution treatment at the speed of 450-500 ℃/1h, immediately carrying out 2-stage aging treatment at the speed of 100-110 ℃/6h + 150-160 ℃/6h after quenching, and enabling a coarse crystal layer to recover and recrystallize and be converted into fine crystal grains under the condition that the crystal grains are kept in an isometric crystal state.

2. The method of claim 1, wherein the pure Al is heated to 800 ℃ in a melting furnace.

3. The method of claim 1, wherein the refining agent is hexachloroethane.