Low-carbon high-strength die-casting anode aluminum alloy and preparation method and application thereof

Abstract

The invention discloses a low-carbon high-strength die-casting anode aluminum alloy and a preparation method and application thereof, and relates to the field of die-casting aluminum alloys and products thereof. The die-casting anode aluminum alloy is composed of the following components in percentage by mass: 1.61-3.0% of Mn; 0.85 to 4.7 percent of Mg; 0.01 to 3.8 percent of Zn; si < = 0.45%; fe < = 0.55%; cu < = 0.8%; 0.0001% to 0.012% of C; 0.005% to 0.10% of M; 0.002 to 0.6 percent of Ti; 0.001% to 0.4% of B; m is at least one of Nb, Y, La, Er and Sm. The content of impurities is less than or equal to 0.2 wt%; ti, B, C and M are added in the form of an Al-Ti-B-C-M composite fine grain alterant. The die-casting aluminum alloy which is low in cost, uniform in anodic oxidation appearance, free of different colors, excellent in comprehensive performance and capable of forming and machining thin-wall part products can be obtained.

Description

Technical Field

[0001] The present application relates to the field of die-cast aluminum alloys and products thereof, and in particular to a low-carbon, high-strength die-cast anode aluminum alloy and a preparation method and application thereof. Background Art

[0002] Aluminum alloy materials have low density and high strength, and their appearance can be surface-treated through anodizing. After anodizing, they have the characteristics of diverse colors, high brightness, and excellent protective effects. They are widely used in 3C electronic consumer products, automotive interior parts, craft exhibits and other fields.

[0003] Patent publication number CN117144199A discloses a high-strength, high-fluidity, anodizable Al-Mn die-casting alloy and its preparation method. The alloy comprises: Mn 1.2-2.1 wt%, Mg 0.3-4.3 wt%, Zn 0-3.6 wt%, Sm 0.08-1.0%, Nb 0.17-0.6%, Ce 0-0.5 wt%, Si 0-0.15 wt%, Cu 0-0.5%, Fe 0-0.25%, Ti 0-0.1 wt%, and other impurities ≤ 0.2 wt%, with the remainder being Al. The alloy has high fluidity and can be formed into thin-walled products using conventional die-casting processes. The anodized surface is uniform and has no discoloration. However, the Fe and Si contents in this patent are strictly controlled. In actual production, Fe and Si are introduced during the raw material intake, alloying, smelting, and die-casting processes, which can easily lead to a continuous accumulation of Fe and Si in the die-cast aluminum alloy. Therefore, it is necessary to reduce the use of recycled materials in the production process of die-cast aluminum alloy.

[0004] Recycled materials are the unavoidable non-product components produced during the production of die-cast aluminum alloy castings. Their composition is similar to that of the original die-cast aluminum alloy. Therefore, to save costs, recycled materials can generally be used to replace some pure aluminum ingots during die-cast aluminum alloy production, thereby reducing the amount of pure aluminum ingots used. Because recycled materials do not undergo energy-intensive processing such as ore smelting and purification, they have lower carbon emissions and are more environmentally friendly. Therefore, effectively reusing this recycled material will play a significant role in reducing carbon emissions and lowering the cost of aluminum ingot production.

[0005] Therefore, how to obtain a die-cast aluminum alloy with low cost, uniform anodized appearance without discoloration, excellent comprehensive performance, and the ability to form and process thin-walled products has important research significance. Summary of the Invention

[0006] In order to obtain a die-cast aluminum alloy with low cost, uniform anodized appearance without discoloration, excellent comprehensive performance, and the ability to form and process thin-walled products, the present application provides a low-carbon, high-strength die-cast anode aluminum alloy and its preparation method and application.

[0007] In the first aspect, the present application provides a low-carbon, high-strength die-cast anode aluminum alloy and its preparation method and application using the following technical solutions: A low-carbon, high-strength die-cast anode aluminum alloy, the composition of the die-cast anode aluminum alloy is: Mn: 1.61-3.0 wt%; Mg: 0.85-4.7wt%; Zn: 0.01~3.8wt%; Si: ≤0.45wt%; Fe: ≤0.55wt%; Cu: ≤0.8wt%; C: 0.0001~0.012wt%; M: 0.005~0.10wt%; Ti: 0.002-0.6wt%; B: 0.001~0.4wt%; The balance is Al and impurities, wherein the content of impurities is ≤0.2wt%; M is at least one of Nb, Y, La, Er, and Sm; Ti, B, C, and M are added in the form of an Al-Ti-BCM composite fine-grained modifier.

[0008] Fe and Si easily react with Al to form an AlFeSi phase, which, on the one hand, affects solidification fluidity and thus the uniformity of the structure, resulting in uneven anode color. Furthermore, during the anodization process, insoluble AlFeSi particles easily corrode and fall off from the substrate, forming surface pits, which also affect the anode color. Furthermore, when AlFeS particles are not completely detached, they are encapsulated in the oxide film, further affecting the anode color. Therefore, patent publication number CN117144199A requires strict control of the amount of Fe and Si used.

[0009] In this application, Mn and Mg can improve the basic fluidity of aluminum alloys, while the Al-Ti-BCM composite fine-grain modifier can refine the aluminum alloy structure. The flow-improving effects of Mn and Mg, combined with the refining effect of the Al-Ti-BCM composite fine-grain modifier, can reduce the sensitivity of the aluminum alloy's anodized appearance to Fe and Si content. A uniform anodic color can be achieved when the Si content does not exceed 0.45wt% and the Fe content does not exceed 0.55wt%. Furthermore, since the sensitivity of the aluminum alloy's anodized appearance to Fe and Si content is reduced, the amount of recycled material used in the aluminum alloy can be increased, resulting in low carbon emissions. Furthermore, Mg, Zn, and Cu can form strengthening and solid solution phases with Al, enhancing the strength of the aluminum alloy. Specifically, the combination of Mn, Mg, the Al-Ti-BCM composite fine-grain modifier, and Zn and Cu can produce a low-cost, high-strength aluminum alloy with a uniform anodic color. This alloy can be used in consumer electronics, automotive interiors, craft exhibits, and aviation parts.

[0010] In this application, Ti, B, C, and M are added in the form of an Al-Ti-BCM composite fine-grain modifier. This allows for the full interaction between Al, Ti, B, C, and M during ball milling and sintering, leveraging the advantages of a large powder bonding surface and high sintering temperature. This facilitates alloy microstructure refinement. If M and Al-Ti-BC are added separately to the aluminum liquid, the Al-Ti-BC and M will each pre-form refined particles and will no longer interact, making it difficult to effectively refine the AlFeSi phase and, consequently, failing to effectively reduce the sensitivity of the aluminum alloy's anodized appearance to the Fe and Si content.

[0011] In addition, M specifically adopts at least one of Nb, Y, La, Er, and Sm. Compared with rare earth elements such as Ce and Nd, Nb, Y, La, Er, and Sm have a more significant effect on improving the refinement effect of the AlFeSi phase. In some specific embodiments, the composition of the die-casting anode aluminum alloy is: Mn: 1.65-2.40 wt%; Mg: 0.95-3.7wt%; Zn: 0.01~1.90wt%; Si: ≤0.45wt%; Fe: ≤0.55wt%; Cu: 0.01-0.65wt%; C: 0.0001~0.005wt%; M: 0.01~0.08wt%; Ti: 0.01-0.48wt%; B: 0.01~0.12wt%.

[0012] In the present application, when the content of each of the above elements is within the above range, the coordination of the elements can reduce the sensitivity of the anodized appearance of the aluminum alloy to the Fe and Si contents while further improving the strength and elongation of the aluminum alloy.

[0013] In some specific embodiments, the preparation method of the Al-Ti-BCM composite fine-grained modifier includes the following steps: Step 1: Raw material preparation: Al-Ti, Al-C, Al-B, and Al-M powders are used as raw materials and mixed in specific proportions; Step 2: Refining the mixed material: ball milling the mixed alloy powder; Step 3, alloying: vacuum sintering and alloying the ball-milled alloy powder to obtain the Al-Ti-BCM composite fine-grained modifier.

[0014] This application utilizes the advantages of large bonding surface and high sintering temperature of powder during ball milling and sintering, so that Al, Ti, B, C and M fully interact with each other, which is beneficial to improving the refining effect of Al-Ti-BCM composite fine grain modifier.

[0015] In some specific embodiments, in step 2, the particle size of the alloy powder after ball milling is in the range of 5 to 20 μm.

[0016] If the particle size of the alloy powder after ball milling is too small, production efficiency will be reduced. At the same time, impurities such as oxide film may be introduced due to the large surface area. If the particle size of the alloy powder after ball milling is too large, the interaction between the elements will be insufficient, and the refining effect of the Al-Ti-BCM composite fine grain modifier will be reduced.

[0017] In some specific embodiments, in step 3, the sintering temperature is 950-1150° C., the sintering time is 20-50 min, the pressure is 35-70 MPa, and the holding time is 20-40 min.

[0018] Too long a holding time will cause the refined phase to coarsen and reduce the refining efficiency. Too short a holding time will result in insufficient interaction between Al, Ti, B, C and M, which will also reduce the refining effect of the Al-Ti-BCM composite fine grain modifier.

[0019] In some specific embodiments, M includes Nb and at least one of Y, La, Er, and Sm.

[0020] In the present application, M is preferably Nb and at least one of Y, La, Er, and Sm. For example, M is a combination of Nb and Y, or M is a combination of Nb and La, or M is a combination of Nb and Er, or M is a combination of Nb and Sm, which is beneficial to further improve the fluidity and elongation of the aluminum alloy.

[0021] In some specific embodiments, the weight ratio of Nb to Y or Nb to La or Nb to Er or Nb to Sm is 1:(3-4).

[0022] In the present application, M is preferably a combination element with a weight ratio of Nb and Y or Nb and La or Nb and Er or Nb and Sm of 1: (3 to 4), which can effectively improve the fluidity problem caused by excessive Fe and Si content, and can further effectively improve the elongation of the die-cast aluminum alloy.

[0023] In a second aspect, the present application provides a method for preparing a low-carbon, high-strength die-cast anode aluminum alloy using the following technical solutions: A method for preparing a low-carbon, high-strength die-cast anode aluminum alloy comprises the following steps: Step S1, weighing pure Al ingot, recycled material, pure Mg ingot, pure Zn ingot, Al-Cu, Al-Mn, Al-Ti-BCM composite fine grain modifier as raw materials according to the ratio; Step S2: melt the pure Al ingot, keep it warm at 710-730°C for 2h, add pure Zn ingot, Al-Cu, Al-Mn and recycled materials, keep it warm, heat it to 750-770°C, add Al-Ti-CBM composite fine grain modifier, keep it warm, and finally cool it to 710-730°C and press in the pure Mg ingot, keep it warm, degas and filter, then cast and cool to obtain low carbon and high strength die-cast anode aluminum alloy.

[0024] This application combines the Al-Ti-BCM composite fine-grained modifier prepared by the solid powder method, which makes the element distribution more uniform, the refined phase particle size is small, the distribution is uniform, and the impurity content is low. It can reduce the sensitivity of the aluminum alloy anodizing appearance to the Fe and Si content while further improving the strength and elongation of the aluminum alloy.

[0025] In a third aspect, the present application provides an aluminum alloy casting obtained by vacuum die-casting of any one of the above-mentioned low-carbon, high-strength die-cast anode aluminum alloys.

[0026] In a fourth aspect, the present application provides a method for preparing an aluminum alloy casting using the following technical solution: A method for preparing an aluminum alloy casting comprises the following steps: Step 1: heating the low-carbon high-strength die-cast anode aluminum alloy to 730-750° C. and melting to obtain alloy liquid; Step 2: Control the mold temperature to 200-230°C, under the condition of vacuum degree of 30-50 mbar, control the low-speed section injection speed to 0.1-0.5 m / s, and the high-speed section injection speed to 3-4 m / s, inject the alloy liquid into the mold, and then cool and demold to obtain an aluminum alloy casting.

[0027] The present application preferably controls the air pressure in the mold to be between 30 and 50 mbar, which can not only meet the requirements of grain refinement, but also prevent excessive vacuum from causing excessively long vacuuming time and adversely affecting production efficiency.

[0028] In summary, this application has at least the following beneficial technical effects: (1) In the present application, Ti, B, C, and M are added in the form of an Al-Ti-BCM composite fine-grain modifier. During the ball milling and sintering process, the advantages of a large powder bonding surface and a high sintering temperature can be utilized to fully interact with each other among Al, Ti, B, C, and M, which is beneficial to improving the alloy structure refinement effect.

[0029] (2) Mn and Mg can improve the basic fluidity of aluminum alloys. Al-Ti-BCM composite fine-grained modifier can refine the structure of aluminum alloys. The flow improvement effect of Mn and Mg combined with the refining effect of Al-Ti-BCM composite fine-grained modifier can reduce the sensitivity of aluminum alloy anodized appearance to Fe and Si content. When the Si content does not exceed 0.45wt% and the Fe content does not exceed 0.55wt%, aluminum alloys with uniform anodic color can be obtained. Moreover, since the sensitivity of aluminum alloy anodized appearance to Fe and Si content is reduced, the amount of recycled materials used in aluminum alloys can be increased, which has the advantage of low carbon emissions. At the same time, Mg, Zn, and Cu can form strengthening phases and solid solution phases with Al, which can improve the strength of aluminum alloys. That is, by combining Mn, Mg, Al-Ti-BCM composite fine-grained modifier and Zn and Cu, aluminum alloys with low cost, uniform anodic appearance color, and high strength can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a picture of the mobile phone frame made of the anodic aluminum alloy in Example 2 of the present application after anodizing treatment.

[0031] Figure 2 This is a picture of the mobile phone frame made of the anodized aluminum alloy in Comparative Example 1 of the present application after anodizing treatment.

[0032] Figure 3 This is the metallographic structure diagram of the anode aluminum alloy in Example 2 of the present application.

[0033] Figure 4 This is the metallographic structure diagram of the anode aluminum alloy in Comparative Example 1 of this application. DETAILED DESCRIPTION

[0034] The present application is further described below in conjunction with specific experiments.

[0035] The present application discloses a low-carbon, high-strength die-cast anode aluminum alloy. The weight percentages of the elements in the low-carbon, high-strength die-cast anode aluminum alloy in Examples 1-3 are shown in Table 1 below: Table 1 [Example 1] In the low-carbon, high-strength die-cast anode aluminum alloy of Example 1, M is specifically La, and Ti, C, B, and La are added in the form of an Al-Ti-CB-La composite fine-grained modifier. Furthermore, the preparation method of the Al-Ti-CB-La composite fine-grained modifier in Example 1 includes the following steps: Step 1, raw material preparation: Al-10Ti, Al-2C, Al-5B, Al-10La powders are used as raw materials, with a powder particle size of ≤50 μm. Al-10Ti, Al-2C, Al-5B, Al-10La powders are weighed according to the amounts of Ti, C, B, and La in Example 1, and mixed uniformly to obtain alloy powder; Step 2: Mixing and refining: ball mill the alloy powder. During the ball milling process, control the gas pressure in the furnace to 10 － 3 Pa grade, ball-to-material ratio of 20:1, rotation speed of 200r / min, ball milling time of 12h, the particle size range of the alloy powder after ball milling is 5-20μm; Step 3, alloying: the ball-milled alloy powder is placed in a vacuum hot pressing furnace for sintering and alloying. The sintering temperature is controlled to be 700°C, the sintering time is 50 min, the pressure is 35 MPa, and the holding time is 40 min to obtain an Al-Ti-BC-La composite fine-grained modifier.

[0036] In this embodiment, the method for preparing a low-carbon high-strength die-cast anode aluminum alloy comprises the following steps: Step S1, weighing pure Al ingot, recycled material, pure Mg ingot, pure Zn ingot, Al-Cu, Al-Mn, Al-Ti-BC-La composite fine-grained modifier as raw materials according to the ratio of each element in Example 1; Step S2: melt the pure Al ingot, keep it at 710°C for 2.5h, add pure Zn ingot, Al-Cu, Al-Mn and recycled materials, keep it warm for 20min, raise the temperature to 750°C, add Al-Ti-CB-La composite fine grain modifier, keep it warm for 20min, and finally cool it to 710°C and press in the pure Mg ingot, keep it warm for 20min, degas and filter, then cast and cool to obtain low carbon and high strength die-cast anode aluminum alloy.

[0037] [Example 2] In the low-carbon, high-strength die-cast anode aluminum alloy of Example 2, M is specifically Nb, and Ti, C, B, and Nb are added in the form of an Al-Ti-CB-Nb composite fine-grained modifier. Furthermore, the preparation method of the Al-Ti-CB-Nb composite fine-grained modifier in Example 2 includes the following steps: Step 1, raw material preparation: Al-10Ti, Al-2C, Al-5B, Al-5Nb powders are used as raw materials, with a powder particle size of ≤50 μm. Al-10Ti, Al-2C, Al-5B, Al-5Nb powders are weighed according to the amounts of Ti, C, B, and Nb in Example 1, and mixed uniformly to obtain alloy powder; Step 2: Mixing and refining: ball mill the alloy powder. During the ball milling process, control the gas pressure in the furnace to 10 － 3 Pa level, ball-to-material ratio of 20:1, rotation speed of 250r / min, ball milling time of 10h, the particle size range of the alloy powder after ball milling is 5-20μm; Step 3, alloying: the ball-milled alloy powder is placed in a vacuum hot pressing furnace for sintering and alloying. The sintering temperature is controlled to be 950°C, the sintering time is 50 min, the pressure is 50 MPa, and the holding time is 30 min to obtain an Al-Ti-BC-Nb composite fine-grained modifier.

[0038] In this embodiment, the method for preparing a low-carbon high-strength die-cast anode aluminum alloy comprises the following steps: Step S1, weighing pure Al ingot, recycled material, pure Mg ingot, pure Zn ingot, Al-Cu, Al-Mn, Al-Ti-BC-Nb composite fine-grained modifier as raw materials according to the ratio of each element in Example 2; Step S2: melt the pure Al ingot, keep it at 720°C for 2h, add pure Zn ingot, Al-Cu, Al-Mn and recycled materials, keep it warm for 20min, raise the temperature to 760°C, add Al-Ti-CB-Nb composite fine grain modifier, keep it warm for 20min, finally cool it to 720°C and press in the pure Mg ingot, keep it warm for 20min, degas and filter, then cast and cool to obtain low carbon and high strength die-cast anode aluminum alloy.

[0039] [Example 3] In the low-carbon, high-strength die-cast anode aluminum alloy of Example 3, M is specifically Sm, and Ti, C, B, and La are added in the form of an Al-Ti-CB-Sm composite fine-grained modifier. Furthermore, the preparation method of the Al-Ti-CB-Sm composite fine-grained modifier in Example 3 includes the following steps: Step 1, raw material preparation: Al-10Ti, Al-2C, Al-5B, Al-5Sm powders are used as raw materials, with a powder particle size of ≤50 μm. Al-10Ti, Al-2C, Al-5B, Al-5Sm powders are weighed according to the amounts of Ti, C, B, and Sm in Example 1, and mixed uniformly to obtain alloy powder; Step 2: Mixing and refining: ball mill the alloy powder. During the ball milling process, control the gas pressure in the furnace to 10 － 3 Pa grade, ball-to-material ratio of 20:1, rotation speed of 300r / min, ball milling time of 8h, the particle size range of the alloy powder after ball milling is 5-20μm; Step 3, alloying: the ball-milled alloy powder is placed in a vacuum hot pressing furnace for sintering and alloying, the sintering temperature is controlled to be 1150°C, the sintering time is 20 min, the pressure is 70 MPa, and the holding time is 20 min to obtain an Al-Ti-BC--Sm composite fine-grained modifier.

[0040] In this embodiment, the method for preparing a low-carbon high-strength die-cast anode aluminum alloy comprises the following steps: Step S1, weighing pure Al ingot, recycled material, pure Mg ingot, pure Zn ingot, Al-Cu, Al-Mn, Al-Ti-BC-Sm composite fine-grained modifier as raw materials according to the ratio of each element in Example 3; Step S2: melt the pure Al ingot, keep it at 730°C for 1.5h, add pure Zn ingot, Al-Cu, Al-Mn and recycled materials, keep it warm for 20min, raise the temperature to 760°C, add Al-Ti-CB-Sm composite fine grain modifier, keep it warm for 20min, finally cool it to 730°C and press in the pure Mg ingot, keep it warm for 20min, degas and filter, then cast and cool to obtain low carbon and high strength die-cast anode aluminum alloy.

[0041] [Example 4] The difference between Example 4 and Example 2 is that M specifically uses La element, wherein the La element is added to the raw materials of the composite fine-grained modifier in the form of Al-10La powder.

[0042] [Example 5] The difference between Example 5 and Example 2 is that M specifically uses Er element, wherein the Er element is added to the raw materials of the composite fine-grained modifier in the form of Al-5Er powder.

[0043] [Example 6] The difference between Example 6 and Example 2 is that M specifically adopts Y element, wherein Y element is added to the raw materials of the composite fine-grained modifier in the form of Al-10Y powder.

[0044] [Example 7] The difference between Example 7 and Example 2 is that M specifically uses Sm element, wherein the Sm element is added to the raw materials of the composite fine-grained modifier in the form of Al-5Sm powder.

[0045] [Example 8] Example 8 differs from Example 2 in that M is a combination of Nb and La, with a weight ratio of Nb to La of 1:4. The Nb element is added to the raw materials of the composite fine-grained modifier in the form of Al-5Nb powder, and the La element is added to the raw materials of the composite fine-grained modifier in the form of Al-10La powder.

[0046] [Example 9] Example 9 differs from Example 2 in that M is a combination of Nb and La, with a weight ratio of Nb to La of 1:9. The Nb element is added to the raw materials of the composite fine-grain modifier in the form of Al-5Nb powder, and the La element is added to the raw materials of the composite fine-grain modifier in the form of Al-10La powder.

[0047] [Example 10] Example 10 differs from Example 2 in that M is a combination of La and Er, with a weight ratio of La to Er of 1:4. The La element is added to the raw materials of the composite fine-grained modifier in the form of Al-10La powder, and the Er element is added to the raw materials of the composite fine-grained modifier in the form of Al-5Er powder.

[0048] [Example 11] Example 11 differs from Example 2 in that M is a combination of Er and Sm, with a weight ratio of Er to Sm of 1:4. The Er element is added to the raw materials of the composite fine-grained modifier in the form of Al-5Er powder, and the Sm element is added to the raw materials of the composite fine-grained modifier in the form of Al-5Sm powder.

[0049] [Example 12] Example 12 differs from Example 2 in that M is a combination of Er and Y, with a weight ratio of Er to Y of 1:4. The Er element is added to the raw materials of the composite fine-grained modifier in the form of Al-5Er powder, and the Y element is added to the raw materials of the composite fine-grained modifier in the form of Al-10Y powder.

[0050] Comparative Example The weight percentages of the various elements in the low carbon high strength die-cast anode aluminum alloys of Comparative Examples 1-6 are shown in Table 2 below: Table 2 element Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Mn 2.12 0 4.55 2.12 2.12 2.12 Mg 2.43 4.55 0 2.43 2.43 2.43 Si 0.45 0.45 0.45 0.45 0.45 0.71 Fe 0.55 0.55 0.55 0.55 0.55 0.65 M 0 0.042 0.042 0.042 0.042 0.042 Zn 0.85 0.85 0.85 0.85 0.85 0.85 Cu 0.25 0.25 0.25 0.25 0.25 0.25 C 0.0004 0.0004 0.0004 0.0004 0.0004 0.0004 Ti 0.28 0.28 0.28 0.36 0 0.28 B 0.08 0.08 0.08 0 0.36 0.08 Al margin margin margin margin margin margin [Comparative Example 1] The difference between Comparative Example 1 and Example 2 is that Ti, C, and B are added in the form of Al-Ti-CB composite fine-grained modifier, and Nb is added in the form of Al-5Nb.

[0051] [Comparative Example 2] The difference between Comparative Example 2 and Example 2 is that the Mn element is replaced by an equal mass of Mg element.

[0052] [Comparative Example 3] The difference between Comparative Example 3 and Example 2 is that the Mg element is replaced by an equal mass of Mn element.

[0053] [Comparative Example 4] The difference between Comparative Example 4 and Example 2 is that the B element is replaced by an equal mass of Ti element.

[0054] [Comparative Example 5] The difference between Comparative Example 5 and Example 2 is that the Ti element is replaced by an equal mass of the B element.

[0055] [Comparative Example 6] The difference between Comparative Example 6 and Example 2 is that the amount of recycled material is controlled so that the weight percentage of Si is 0.71 wt % and the weight percentage of Fe is 0.65 wt %.

[0056] Application Examples The low-carbon, high-strength die-cast anode aluminum alloy of each embodiment is used to prepare aluminum alloy castings with a thickness of less than 0.6 mm according to the following method. Among them, the preferred method for preparing the aluminum alloy castings is as follows: Step 1: heating the low-carbon high-strength die-cast anode aluminum alloy to 730-750° C. and melting to obtain alloy liquid; Step 2: Control the mold temperature to 200-230°C, under the condition of vacuum degree of 30-50 mbar, control the low-speed section injection speed to 0.1-0.5 m / s, and the high-speed section injection speed to 3-4 m / s, inject the alloy liquid into the mold, and then cool and demold to obtain an aluminum alloy casting.

[0057] Performance testing (1) Die-cast yield strength: The die-casting mold and the size of the tensile rod were designed with reference to the national standard GB / T 13822-2017. The diameter of the tensile rod was Φ6.4 mm. Then, the low-carbon, high-strength die-cast anode aluminum alloys prepared in each embodiment and comparative example were used to prepare test specimens according to the following method. The test specimens were prepared as follows: Step 1: heating the low-carbon high-strength die-cast anode aluminum alloy to 740° C. and melting it to obtain a molten alloy; Step 2: Control the mold temperature to 220°C, under the condition of a vacuum degree of 45 mbar, control the low-speed section injection speed to 0.3 m / s, and the high-speed section injection speed to 3.5 m / s, inject the alloy liquid into the mold, and then cool and demold to obtain a test sample.

[0058] The die-casting yield strength and elongation of the test specimens prepared in each embodiment and comparative example were tested, and the results are recorded in Table 1 below.

[0059] (2) Anodized appearance: The low-carbon, high-strength die-cast anode aluminum alloys prepared in the Examples and Comparative Examples were used to prepare mobile phone frames with a thickness of 0.45 mm. The test samples were prepared as follows: Step 1: heating the low-carbon high-strength die-cast anode aluminum alloy to 740° C. and melting it to obtain a molten alloy; Step 2: Control the mold temperature to 220°C, and under the condition of a vacuum degree of 45 mbar, control the low-speed section injection speed to 0.3 m / s and the high-speed section injection speed to 3.5 m / s, inject the alloy liquid into the mold, and then cool and demold to obtain the mobile phone frame.

[0060] Perform anodizing on the 0.2mm thick mobile phone frame and observe whether the anodized appearance color is uniform and has no different colors.

[0061] Table 3 In addition, see Figure 1 and Figure 2 , this application Figure 1 The anodic oxidation appearance of the mobile phone frame prepared in Example 2 in a vacuum environment with a vacuum degree of 45 mbar after anodizing is shown. Figure 2 The anodized appearance of the mobile phone frame produced in Comparative Example 1 in a vacuum environment with a vacuum degree of 45 mbar is shown. The anodized appearance of the mobile phone frame produced in Example 2 is uniform in color and has no discoloration. The anodized appearance of the mobile phone frame produced in Comparative Example 1 exhibits obvious flow marks and uneven color at the corners.

[0062] See Figure 3 and Figure 4 , this application Figure 3 The metallographic structure diagram of the anode aluminum alloy in Example 2 is shown. Figure 4 The metallographic structure of the anodized aluminum alloy in Comparative Example 1 is shown. The metallographic structure in Example 2 is fine and uniform, with evenly distributed strengthening phases. The metallographic structure in Comparative Example 1 is coarse, with a large number of precipitated phases and large sizes, failing to meet the requirements for uniform anodized appearance.

[0063] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A low-carbon, high-strength die-cast anode aluminum alloy, characterized by: The composition of the die-cast anode aluminum alloy is: Mn: 1.61~3.0wt%; Mg: 0.85~4.7wt%; Zn: 0.01~3.8wt%; Si: ≤0.45wt%; Fe: ≤0.55wt%; Cu: ≤0.8wt%; C: 0.0001~0.012wt%; M: 0.005~0.10wt%; Ti: 0.002~0.6wt%; B: 0.001~0.4wt%; The balance is Al and impurities, wherein the content of impurities is ≤0.2wt%; M is at least one of Nb, Y, La, Er, and Sm; Ti, B, C, and M are added in the form of an Al-Ti-BCM composite fine-grained modifier.

2. The low-carbon, high-strength die-cast anode aluminum alloy according to claim 1, characterized in that: The composition of the die-cast anode aluminum alloy is: Mn: 1.65~2.40wt%; Mg: 0.95~3.7wt%; Zn: 0.01~1.90wt%; Si: ≤0.45wt%; Fe: ≤0.55wt%; Cu: 0.01~0.65wt%; C: 0.0001~0.005wt%; M: 0.01~0.08wt%; Ti: 0.01~0.48wt%; B: 0.01~0.12wt%.

3. The low-carbon, high-strength die-cast anode aluminum alloy according to claim 1, characterized in that: The preparation method of the Al-Ti-BCM composite fine-grained modifier comprises the following steps: Step 1: Raw material preparation: Al-Ti, Al-C, Al-B, and Al-M powders are used as raw materials and mixed in specific proportions; Step 2: Refining the mixed material: ball milling the mixed alloy powder; Step 3, alloying: performing vacuum sintering and alloying on the ball-milled alloy powder to obtain the Al-Ti-BCM composite fine-grained modifier.

4. The low-carbon, high-strength die-cast anode aluminum alloy according to claim 1, characterized in that: In step 2, the particle size of the alloy powder after ball milling is in the range of 5 to 20 μm.

5. The low-carbon, high-strength die-cast anode aluminum alloy according to claim 1, characterized in that: In step 3, the sintering temperature is 950-1150° C., the sintering time is 20-50 min, the pressure is 35-70 MPa, and the holding time is 20-40 min.

6. The low-carbon, high-strength die-cast anode aluminum alloy according to claim 1, characterized in that: M includes Nb and at least one of Y, La, Er, and Sm.

7. The low-carbon, high-strength die-cast anode aluminum alloy according to claim 1, characterized in that: The weight ratio of Nb to Y or Nb to La or Nb to Er or Nb to Sm is 1:(3-4).

8. A method for preparing a low-carbon, high-strength die-cast anode aluminum alloy according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step S1, weighing pure Al ingot, recycled material, pure Mg ingot, pure Zn ingot, Al-Cu, Al-Mn, Al-Ti-BCM composite fine grain modifier as raw materials according to the ratio; Step S2: melt the pure Al ingot, keep it warm at 710-730°C, add pure Zn ingot, Al-Cu, Al-Mn and recycled materials, keep it warm, heat it to 750-770°C, add Al-Ti-CBM composite fine grain modifier, keep it warm, and finally cool it to 710-730°C, press in the pure Mg ingot, keep it warm, degas and filter, then cast and cool to obtain low carbon and high strength die-cast anode aluminum alloy.

9. An aluminum alloy casting, characterized in that: The low-carbon high-strength die-casting anode aluminum alloy according to any one of claims 1 to 7 is obtained by vacuum die-casting.

10. The method for preparing an aluminum alloy casting according to claim 9, characterized in that: The following steps are involved: Step 1: heating the low-carbon high-strength die-cast anode aluminum alloy to 730-750° C. and melting to obtain alloy liquid; Step 2: Control the mold temperature to 200-230°C, under the condition of vacuum degree of 30-50 mbar, control the low-speed section injection speed to 0.1-0.5 m / s, and the high-speed section injection speed to 3-4 m / s, inject the alloy liquid into the mold, and then cool and demold to obtain an aluminum alloy casting.

Images