阅读说明：本技术 手机中板用高强度压铸合金材料及其制备方法和应用 (High-strength die-casting alloy material for mobile phone middle plate and preparation method and application thereof ) 是由 周银鹏 汪时宜 陈曦 胡安 罗云斌 赵华 屈雪莲 陈煜� 于 2020-05-30 设计创作，主要内容包括：本发明涉及一种手机中板用高强度压铸合金材料及其制备方法和应用,该合金材料包括Si：4.0wt％-8.0wt％；Mg：4.0wt％-8.0wt％；Mn：0.4wt％-1.0wt％；Cu<4.0wt％；Zn<1.5wt％；Fe<0.5wt％；Ti<0.25wt％；Sc<1.0wt％；Zr<0.5wt％,其余杂质的重量百分比之和控制在1.0wt％以下,余量为Al。采用压铸与挤压铸造结合的方式制成中级中板,与现有技术相比,本发明所述的高强度压铸合金材料及其制备方法,得到的手机中板抗拉强度能达到350-400MPa,屈服强度达到250-300MPa,延伸率2.0-4.0％。(The invention relates to a high-strength die-casting alloy material for a mobile phone middle plate, and a preparation method and application thereof, wherein the alloy material comprises Si: 4.0 wt% -8.0 wt%; mg: 4.0 wt% -8.0 wt%; mn: 0.4 wt% -1.0 wt%; cu <4.0 wt%; zn <1.5 wt%; fe <0.5 wt%; ti <0.25 wt%; sc <1.0 wt%; zr is less than 0.5 wt%, the sum of the weight percentages of the other impurities is controlled to be less than 1.0 wt%, and the balance is Al. Compared with the prior art, the high-strength die-casting alloy material and the preparation method thereof have the advantages that the tensile strength of the obtained mobile phone middle plate can reach 350-400MPa, the yield strength reaches 250-300MPa, and the elongation is 2.0-4.0%.)

1. The high-strength die-casting alloy material for the mobile phone middle plate is characterized by comprising the following components in percentage by weight: 4.0 wt% -8.0 wt%; mg: 4.0 wt% -8.0 wt%; mn: 0.4 wt% -1.0 wt%; cu <4.0 wt%; zn <1.5 wt%; fe <0.5 wt%; ti <0.25 wt%; sc <1.0 wt%; zr is less than 0.5 wt%, the sum of the weight percentages of the other impurities is controlled to be less than 1.0 wt%, and the balance is Al.

2. The high-strength die-cast alloy material for the middle plate of the mobile phone as claimed in claim 1, wherein the alloy material comprises Si: 6.0 wt% -8.0 wt%; mg: 6.0 wt% -8.0 wt%; mn: 0.4 wt% -1.0 wt%; cu <3.0 wt%; zn <1.5 wt%; fe <0.5 wt%; ti <0.25 wt%; sc <1.0 wt%; zr is less than 0.5 wt%, the sum of the weight percentages of the other impurities is controlled to be less than 1.0 wt%, and the balance is Al.

3. The high-strength die-casting alloy material for the mobile phone middle plate as claimed in claim 1 or 2, wherein the Si, Mg, Mn, Fe and Cu are added in the form of simple substances, and the simple substances of Si, Mg, Mn, Fe, Zn and Cu are preprocessed into cubes with the side length of 15cm and then put into molten aluminum.

4. The high-strength die-casting alloy material for the mobile phone middle plate as claimed in claim 1 or 2, wherein the Ti, Sc and Zr are added in the form of intermediate phase alloy, Al-Ti, Al-Sc and Al-Zr intermediate alloy are adopted, and are preprocessed into nano powder.

5. The high-strength die-casting alloy material for the middle plate of the mobile phone as claimed in claim 1 or 2, wherein the Cu and Al form Al₂Cu, Sc, Zr and Al form Al₃Sc and Al₃(Sc_1-xZr_x) Mg forms Mg with Si₂Si, Mn, Sc, Zr and Al form MnAl₆、Al₃Sc and Al₃(Sc_1-xZr_x) Wherein 0 is<x<1。

6. A method for preparing a high-strength die-casting alloy material for a mobile phone middle plate as claimed in claim 1, comprising the steps of:

1) putting the high-purity aluminum element into a heating furnace, heating to 680 ℃, completely melting and preserving heat for 20 min;

2) heating to 760 ℃, and adding Si, Mn, Fe, Zn and Cu elementary substance elements;

3) heating to 790 ℃, and adding Ti, Sc and Zr intermediate phase alloy nano powder;

4) cooling to 700 ℃, and adding pure Mg metal material;

5) fully and uniformly stirring the melted raw materials, and then removing slag and degassing;

6) after deslagging and degassing operation, keeping the temperature of the alloy solution for standing for 20 min;

7) taking a small amount of alloy solution, casting into a material ingot, and detecting whether the alloy components meet the requirements through a spectrometer;

8) and after the components of each element of the alloy solution are qualified, casting an aluminum ingot groove to obtain an aluminum alloy ingot.

7. The application of the high-strength die-casting alloy material for the mobile phone middle plate as claimed in claim 1, wherein the alloy material is used for manufacturing the mobile phone middle plate, and is subjected to extrusion casting in a vertical feeding mode, and specifically comprises the following steps: pouring the aluminum alloy liquid into a vertical charging basket of a horizontal extrusion casting machine, moving and swinging the charging basket to a position right below a die of the horizontal extrusion casting machine, and injecting and filling the aluminum alloy liquid metal into a die cavity of the die in a vertical upward injection mode through a hydraulic mechanism at an ingate speed of 20-100 m/s to obtain an extrusion casting thin-walled part.

8. The use of the high strength die casting alloy material for the mobile phone middle plate according to claim 7, wherein the vertical cylinder of the horizontal extrusion casting machine is vertical, and after charging, the cylinder is filled to 100%;

the hydraulic mechanism is a vertical injection hydraulic mechanism, and the movement speed of the punch pushed by an injection piston rod of the hydraulic mechanism is designed to be 4-8 m/s.

9. The use of the high strength die-cast alloy material for the middle plate of a mobile phone according to claim 7, wherein the wall thickness of the thin-walled part of the middle plate of a mobile phone manufactured by extrusion casting is 0.3-1.0 mm.

10. The use of the high strength die-casting alloy material for the middle plate of a mobile phone as claimed in claim 7, wherein the tensile strength of the middle plate of a mobile phone can reach 350-400MPa, the yield strength can reach 250-300MPa, and the elongation is 2.0-4.0%.

Technical Field

The invention belongs to the technical field of aluminum alloy high-pressure casting, relates to a high-strength die-casting alloy material, and particularly relates to a preparation method and application of the high-strength die-casting alloy material for a mobile phone middle plate.

Background

Currently, it is the high-speed development phase of the 5G industry. With the development of the 5G technology and the increasing perfection of the matched industrial chain, the 5G mobile phone will become the mainstream of the future mobile phone market. The whole industry looks good at the change tide brought by 5G, and the change of the appearance piece of the mobile phone is from a plastic shell to a metal mobile phone shell before 10 years, and then to the replacement of a non-metal mobile phone shell. The mobile phone middle plate is also required to be advanced as a key part of the mobile phone, and the used material is more important.

The device quantity increases by a wide margin in the 5G cell-phone, and the integration promotes and brings the mainboard and upgrade. The device quantity on the mainboard in the 5G cell-phone will increase by a wide margin, and the integrated level promotes by a wide margin in limited space, and chip I/O number increases, and the size of I/O pitch will also further reduce, leads to pad pitch, diameter to reduce, walks the line density and increases. The effect of this is that the thickness of the midplane decreases and the forces that the midplane needs to withstand are greater.

Therefore, a die-casting aluminum alloy material which is suitable for the thin-wall and high-yield mobile phone middle plate and ensures a certain elongation rate is urgently needed to be developed, so that the high-performance mobile phone middle plate can be rapidly produced and manufactured.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a high-strength die-casting alloy material for a mobile phone middle plate, which can cope with increasingly complex mobile phone structures and can bear larger stress, and a preparation method and application thereof.

The purpose of the invention can be realized by the following technical scheme: a high-strength die-casting alloy material for a mobile phone middle plate comprises Si: 4.0 wt% -8.0 wt%; mg: 4.0 wt% -8.0 wt%; mn: 0.4 wt% -1.0 wt%; cu <4.0 wt%; zn <1.5 wt%; fe <0.5 wt%; ti <0.25 wt%; sc <1.0 wt%; zr is less than 0.5 wt%, the sum of the weight percentages of the other impurities is controlled to be less than 1.0 wt%, and the balance is Al.

Further preferably, the alloy material includes Si: 6.0 wt% -8.0 wt%; mg: 6.0 wt% -8.0 wt%; mn: 0.6 wt% -0.8 wt%; cu <3.0 wt%; zn <1.0 wt%; fe <0.5 wt%; ti <0.25 wt%; sc <1.0 wt%; zr is less than 0.5 wt%, the sum of the weight percentages of the other impurities is controlled to be less than 1.0 wt%, and the balance is Al.

The Si, Mg, Mn, Fe and Cu are added in a simple substance form, wherein the simple substances of the Si, the Mg, the Mn, the Fe and the Cu are preprocessed into cubes with the side length of 15cm, and then the cubes are put into aluminum liquid.

The Ti, Sc and Zr are added in the form of intermediate phase alloy, Al-Ti, Al-Sc and Al-Zr intermediate alloy is adopted, and the intermediate alloy is preprocessed into nano powder.

The Cu and Al form Al₂Cu, Sc, Zr and Al form Al₃Sc and Al₃(Sc_1-xZr_x) Mg forms Mg with Si₂Si, Mn, Sc, Zr and Al form MnAl₆、Al₃Sc and Al₃(Sc_1-xZr_x) Wherein 0 is<x<1。

The invention also aims to provide a preparation method of the high-strength die-casting alloy material for the middle plate of the mobile phone, which comprises the following steps:

1) putting the high-purity aluminum element into a heating furnace, heating to 680 ℃, completely melting and preserving heat for 20 min;

2) heating to 760 ℃, and adding Si, Mn, Fe, Zn and Cu elementary substance elements;

3) heating to 790 ℃, and adding Ti, Sc and Zr intermediate phase alloy nano powder;

4) cooling to 700 ℃, and adding pure Mg metal material;

5) fully and uniformly stirring the melted raw materials, and then removing slag and degassing;

6) after deslagging and degassing operation, keeping the temperature of the alloy solution for standing for 20 min;

7) taking a small amount of alloy solution, casting into a material ingot, and detecting whether the alloy components meet the requirements through a spectrometer;

8) and after the components of each element of the alloy solution are qualified, casting an aluminum ingot groove to obtain an aluminum alloy ingot.

The preparation method of the mobile phone middle plate provided by the invention is novel extrusion casting, and adopts a working mode of closing a die in a vertical extrusion bedroom to carry out high-speed and high-pressure casting, so that the mobile phone middle plate with good performance is obtained. The extrusion casting method is different from the traditional extrusion casting, the injection speed of the traditional extrusion casting is 0.01-1 m/s, the extrusion casting speed of the preparation method is equivalent to that of die casting, the air injection can be realized at 4-8 m/s, the filling speed of a thin-walled part can be completely met, and the high-speed vertical injection is realized.

The application method of the high-strength die-casting alloy material for the mobile phone middle plate comprises the following specific preparation characteristics that the alloy material is used for manufacturing the mobile phone middle plate: the method comprises the steps of smelting an aluminum alloy cast ingot to obtain aluminum alloy liquid metal, pouring the aluminum alloy liquid metal into a charging barrel of a horizontal extrusion casting machine, carrying out horizontal die assembly on a die, enabling the charging barrel to move and swing to the position right below the die, and carrying out injection filling on the aluminum alloy liquid metal into a die cavity of the die at an ingate speed of 20-100 m/s in a vertical upward injection mode through a hydraulic mechanism to obtain an extrusion casting thin-wall part. The method for preparing the mobile phone middle plate is different from the traditional die-casting method, the traditional mobile phone middle plate die-casting method adopts a horizontal feeding mode to perform die filling and injection molding, the air above the charging barrel is moved by the aluminum alloy liquid through uniform acceleration of the punch, the aluminum liquid is slowly discharged from the inner pouring gate through a mode that the punch pushes the aluminum liquid, and the traditional die-casting middle plate charging barrel is horizontal, so that the fullness of the aluminum alloy liquid in the charging barrel is only 15-30 percent, the charging barrel structure is easy to draw gas into a casting, the problem of air holes cannot be fundamentally solved, the preparation method adopts vertical feeding, the fullness of the charging barrel is 100 percent, the problem of air entrainment is fundamentally solved, and the high-pressure casting performance of the mobile phone.

The aluminum alloy liquid is poured in the vertical charging barrel, the aluminum alloy skin inside the charging barrel is quickly oxidized, the oxide layer is brought into a slag ladle in a vertical injection mode, impurities such as punch oil at the bottom of the charging barrel are pressed into the charging handle, the obtained middle plate casting is the purest material, the performance is optimal, and the method is different from the traditional die-casting method. The traditional middle plate die casting is to form the oxide skin and the aluminum liquid after mixing at high pressure, and the obtained mobile phone middle plate is mixed with more impurities and is not beneficial to the mechanical property and the heat conducting property of the material.

Pouring the aluminum alloy liquid metal into a charging barrel of an extruder, closing the die, moving and swinging the charging barrel to the position right below the die, and instantly injecting the aluminum alloy liquid metal into a die cavity of the die in a vertical injection mode through a hydraulic mechanism to obtain an extrusion casting thin-wall part.

And the hydraulic mechanism is used for injecting a piston rod to push the punch to move at a speed of 4-8 m/s.

And the gate speed of the hydraulic mechanism for spraying the aluminum alloy liquid metal into the mold cavity is 20-100 m/s.

The wall thickness of the extrusion casting thin-wall part is 0.3-1.0 mm.

The tensile strength of the mobile phone middle plate can reach 350-400MPa, the yield strength reaches 250-300MPa, and the elongation is 2.0-4.0%.

The injection part of the preparation method is different from the traditional die-casting and extrusion casting, the high-speed and high-pressure performance of the die-casting is utilized, the moving speed of a punch can reach 8m/s under the high-pressure action of a hydraulic mechanism, the injection speed can be adjusted by adjusting the flow of the hydraulic mechanism, and the vertical exhaust scheme of the extrusion casting is combined.

According to the preparation method, the aluminum alloy middle plate with medium strength and medium heat conductivity is obtained by carrying out component proportioning, smelting, stirring, solidifying, cooling, high-speed extrusion casting and molding.

Furthermore, the preparation mode of the mobile phone middle plate adopts a vertical injection manufacturing mode, which is beneficial to mold filling and mold exhaust.

Furthermore, the preparation method of the mobile phone middle plate adopts a high-speed and high-pressure mode to carry out pressure casting, and the casting specific pressure is far greater than that of a common die casting.

Furthermore, the preparation method of the mobile phone middle plate has the advantages that the injection speed can reach 8m/s at most, and the high-speed filling requirement of thin-wall parts is met.

Furthermore, the preparation method of the mobile phone middle plate adopts a local pressurization method (instantaneous local extrusion is carried out by adopting the extrusion pin and the belleville spring), the local extrusion casting pressure can reach 150-200 MPa, the solidification feeding is increased, the grain structure is refined, the product is more compact, and the mechanical property is enhanced.

Compared with the prior art, the invention has the following beneficial effects:

1) cu, Mn and Fe are added into the aluminum alloy, and a strengthening phase MnAl is introduced₆And Al₂And Cu, which obviously improves the yield strength of the material.

2) Simultaneous addition of Mg and Si phases to aluminium to produce Mg₂The Si strengthening phase improves the yield strength of the material.

3) Al precipitation of Sc during alloy solidification₃The Sc second phase can become an effective grain core of the aluminum matrix, refine the as-cast grains of the alloy and simultaneously precipitate secondary Al through aging₃The Sc dispersed particles have a direct precipitation strengthening effect on the alloy, and meanwhile, the Sc and Zr composite microalloying can enable Al to be in a micro-alloy state₃Evolution of Sc phase to form Al₃(Sc_1-xZr_x) Composite particles. Has stronger grain refinement effect, and has more obvious effects of substructure strengthening and precipitation strengthening of the raw phase particles.

4) The alloying effect of trace Zr in the Al-Si alloy is researched through mechanical property test and microstructure observation. The results show that the addition of Zr refines the primary crystal Si, eutectic Si and dendrites of the alloy.

5) The preparation method of the mobile phone middle plate adopts a method combining die casting and extrusion casting, completely solves the problem of air entrainment of a charging barrel of a die casting piece by changing the injection speed of the extrusion casting, reduces the air hole content of the middle plate casting piece to a great extent, improves the mechanical property, and simultaneously the casting of the extrusion casting is larger than that of the extrusion casting, so that the prepared middle plate has higher density.

Drawings

Fig. 1 is a metallographic photograph of 50 times of the edge cross section of the plate in the mobile phone;

FIG. 2 is an enlarged view of a portion of FIG. 1;

figure 3 stretches the sheet size.

Detailed Description

The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.