Aluminum alloy containing secondary aluminum, preparation method of aluminum alloy and hub

Abstract

The invention belongs to the technical field of metal material engineering, and particularly relates to an aluminum alloy containing secondary aluminum, a preparation method of the aluminum alloy and a hub, and the preparation method comprises the following steps: placing molten aluminum in a tundish, adding the secondary aluminum, melting and stirring, weighing, adding an intermediate alloy, transporting to the front of a low-pressure casting machine holding furnace, then pouring the molten aluminum, casting the hub and carrying out quality inspection. And feeding the qualified hub into a heat treatment furnace for heat treatment to obtain a finished product. According to the invention, the secondary aluminum is added into the primary aluminum, the production cost and the carbon emission are reduced at the same time, and the formation of a coarse iron phase in a structure is controlled by adding the mixed rare earth, so that compared with a primary aluminum material, the mechanical property of the hub provided by the invention is not reduced in a T6 state.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material engineering, and particularly relates to an aluminum alloy containing recycled aluminum, a preparation method thereof, and a wheel hub. Background Art

[0002] Due to its price advantage, recycled aluminum is widely used in the production of automobile and motorcycle castings, and their proportion in the application of all-aluminum alloys has also been increasing year by year. However, because the composition and metallurgical quality control of recycled aluminum far cannot meet the technical requirements of automotive wheel aluminum, almost no manufacturers currently use recycled aluminum to produce automotive wheel hubs, and a large number of waste wheel hubs can only be remelted and downgraded for use. Therefore, if wheel hubs that meet the performance requirements can be produced from waste recycled aluminum, the dependence on primary aluminum can be reduced.

[0003] Compared with primary aluminum, recycled aluminum has a higher impurity content, poorer microstructure and properties, which limits its use to the production of some mid- to low-end castings. Among these impurities, the most influential is the impurity Fe element. Their content in the aluminum alloy, especially their morphological characteristics, has a great impact on the mechanical properties of the alloy. Therefore, studying the morphology of the iron phase and modifying them into a morphology that has a less significant impact on the mechanical properties of the alloy is crucial for improving the quality of recycled aluminum and expanding its application range.

[0004] The improvement effect of rare earths on the properties of aluminum alloys has received extensive attention from scientific research personnel. Rare earth elements have the dual effects of modification and refinement and impurity removal. Among them, lanthanum and cerium have good modification effects in molten aluminum, and their modification time is long, which can last for more than 5 to 7 hours. Moreover, there is still a good modification effect after remelting 2 to 3 times. In addition, the addition of rare earth elements can not only refine α-Al, but also modify the plates of Si in the alloy, and new rare earth phases such as AlSiLa and Al11Ce3 will be formed. These rare earth phases can be used as heterogeneous nucleation sites during the solidification of A356.2 alloy to refine the microstructure and improve the properties of the alloy. If the characteristics of rare earths can be combined, recycled aluminum can be put into the production of aluminum alloys and applied to wheel hub manufacturing, which can reduce the dependence on primary aluminum in wheel hub production and optimize the recycling link of waste wheel hubs while ensuring the quality of wheel hubs. Summary of the Invention

[0005] The present invention provides an aluminum alloy containing recycled aluminum, a preparation method thereof, and a wheel hub to solve the problems in the prior art that waste wheel hubs can only be remelted and downgraded for use, and the aluminum alloy added with recycled aluminum is affected by impurities.

[0006] To achieve the above object, the present invention provides the following technical solutions: An aluminum alloy containing recycled aluminum, wherein the mass percentages of the components of the aluminum alloy are as follows: Si 6.8 - 7.4%, Mg 0.3 - 0.35%, Ti 0.1 - 0.15%, Fe ≤0.12%, Sr 0.01 - 0.02%, Mn < 0.05%, RE 0.05 - 0.1%, impurity elements ≤0.3%, and the balance is Al.

[0007] Preferably, the RE is specifically La and Ce, and the mass ratio is 1:1.

[0008] Preferably, the RE is specifically La and Ce, and the mass ratio is 2:1.

[0009] Preferably, the RE is specifically La and Sm, and the mass ratio is 4:1.

[0010] A preparation method of an aluminum alloy containing recycled aluminum, comprising the following steps; Step 1, place molten aluminum in the tundish; Step 2, add recycled aluminum to the molten aluminum, and stir evenly after melting; Step 3, weigh the Al-Re master alloy according to the target composition, add the weighed Al-Re master alloy to the tundish, stir and then degas, and sprinkle a refining agent on the degassed molten aluminum to obtain the aluminum alloy containing recycled aluminum.

[0011] Preferably, the molten aluminum in Step 1 is primary A356 molten aluminum.

[0012] Preferably, the mass of the recycled aluminum in Step 2 accounts for 50 - 70% of the molten aluminum in Step 1.

[0013] Preferably, the Al-Re master alloy in Step 3 includes Al-Ce master alloy, Al-La master alloy and Al-Sm master alloy.

[0014] A wheel hub, which is prepared from the aluminum alloy containing recycled aluminum described above.

[0015] The beneficial effects of the present invention are as follows: The present invention provides an aluminum alloy containing recycled aluminum. By adding recycled aluminum to primary aluminum, the production cost and carbon emissions are reduced. Moreover, by adding mixed rare earths to control the formation of coarse iron phases in the structure, compared with primary aluminum materials, the mechanical properties of the products made of the aluminum alloy proposed by the present invention will not decrease in the T6 state. Description of the Drawings

[0016] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a flow chart of a preparation method of an aluminum alloy containing recycled aluminum; Figure 2 It is a metallographic structure picture of the outer rim of the wheel hub in Example 1; Figure 3 It is a metallographic structure picture of the outer rim of the wheel hub in Example 2; Figure 4 It is a metallographic structure picture of the outer rim of the wheel hub in Example 3. Detailed implementation manners

[0017] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0018] The following detailed descriptions are all exemplary descriptions, aiming to provide further detailed descriptions of the present invention. Unless otherwise specified, all technical terms adopted by the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the present invention are only for describing specific implementation manners, and are not intended to limit the exemplary embodiments according to the present invention.

[0019] The present invention provides an aluminum alloy containing recycled aluminum, and a wheel hub is produced by a low-pressure casting process. The mass percentages of its various components are: Si 6.8 - 7.4%, Mg 0.3 - 0.35%, Ti 0.1 - 0.15%, Fe ≤ 0.12%, Sr 0.01 - 0.02%, Mn < 0.05%, RE 0.05 - 0.1%, impurity elements ≤ 0.3%, and the balance is Al.

[0020] After adding rare earth to the aluminum alloy, the yield strength of the outer rim after T6 heat treatment of the wheel produced by low-pressure casting is ≥ 180 MPa, and the elongation is ≥ 13%.

[0021] The recycled aluminum is obtained after front-end material selection. The mass percentages of its various components are: Si 6.5 - 7.5%, Mg ≤ 0.35%, Ti 0.1 - 0.15%, Fe < 0.16%, Sr < 0.03%, Mn < 0.05%, impurity elements ≤ 0.3%, and the balance is Al.

[0022] In a specific implementation manner, for the aluminum alloy, the mass ratio of the recycled aluminum added on the basis of the primary A356 is 50% - 70%.

[0023] In a specific implementation manner, the rare earth RE includes La and Ce, and the ratio is 1:1.

[0024] In a specific implementation manner, the rare earth RE includes La and Sm, and the ratio is 2:1.

[0025] In a specific embodiment, the rare earth RE includes Ce and Sm, and the ratio is 4:1.

[0026] The present invention also provides a method for preparing an aluminum alloy containing recycled aluminum, as Figure 1 shown, which includes the following steps: Step 1, prepare primary A356 aluminum liquid in a tundish; Step 2, add recycled aluminum with a mass ratio of 50-70% relative to the original component content to the components selected in Step 1, melt and stir evenly, and skim the surface scum; Step 3, weigh the Al-Re master alloy according to the target composition, add the weighed Al-Re master alloy to the tundish in a set ratio, stir for 5-10 minutes and then degas, and then sprinkle a refining agent on the surface of the degassed material to obtain an aluminum alloy containing recycled aluminum.

[0027] After adding the weighed rare earth elements in Step 3, the AlFeSiRe phase is generated, controlling the formation of coarse iron phases in the structure.

[0028] In a specific embodiment, the Al-Re master alloy in Step 3 includes an Al-Ce master alloy, an Al-La master alloy, and an Al-Sm master alloy.

[0029] The present invention also provides a wheel hub, which is prepared from the above aluminum alloy containing recycled aluminum.

[0030] In a specific embodiment, the specific preparation method of the wheel hub is based on the preparation method of the aluminum alloy containing recycled aluminum, and the following steps are added: Step 4, transfer the tundish to the front of the holding furnace of the low-pressure casting machine, then pour the aluminum liquid, and start the low-pressure casting machine to complete the low-pressure casting process of the wheel hub.

[0031] Step 5, the produced wheel hub is sent to the next process by a conveyor belt. After confirming that there are no obvious casting defects on the surface, it is sent to the X-ray room for flaw detection, and the wheel hubs that do not meet the requirements are removed; Step 6, send the wheel hub obtained in Step 5 to the heat treatment furnace by a conveyor belt, and perform heat treatment at a set heat treatment temperature to obtain the wheel hub. Example

[0032] An aluminum alloy containing recycled aluminum, the mass percentages of its components are selected as: Si 6.8%, Mg 0.32%, Ti 0.12%, Fe 0.09%, Sr 0.011%, La 0.045%, Ce 0.048%, and the balance is Al.

[0033] In this embodiment, the aluminum alloy of recycled aluminum is used to prepare a wheel hub, and the preparation method of the aluminum alloy containing recycled aluminum is specifically as follows: Step 1: Prepare 1.0 ton of primary A356 aluminum liquid in a tundish.

[0034] Step 2: Pour 50% recycled aluminum into the tundish, stir evenly after melting, and skim the surface scum with a ladle.

[0035] Step 3: Weigh the Al-Ce master alloy and Al-La master alloy according to the target alloy composition to obtain the weighed Al-20La and Al-20Ce master alloys. Add the weighed Al-20La and Al-20Ce master alloys to the tundish according to the set ratio, stir for 5 - 10 min, then degas, and then sprinkle with a refining agent to remove impurities, thus completing the preparation of the aluminum alloy.

[0036] Furthermore, for preparing the wheel hub: After skimming the slag, transfer the tundish to in front of the holding furnace of the die-casting machine, pour the aluminum liquid, start the low-pressure casting machine to complete the low-pressure casting, and obtain the cast wheel hub. Conduct quality inspection on the cast wheel hub, reject the wheel hubs that do not meet the requirements, and obtain qualified wheel hubs. Conduct heat treatment on the qualified wheel hubs to complete the casting and obtain the wheel hubs.

[0037] The metallographic structure picture obtained by sampling the outer rim of the wheel hub is as Figure 2 shown.

[0038] In a specific embodiment, the quality inspection in Step 5 includes checking whether there are obvious defects on the surface of the wheel hub and sending the wheel hub into an X-ray chamber for flaw detection. Embodiment

[0039] For an aluminum alloy containing recycled aluminum, the mass percentages of its various components are selected as: Si 6.8%, Mg 0.32%, Ti 0.12%, Fe 0.09%, Sr 0.011%, La 0.061%, Ce 0.032%, and the balance is Al.

[0040] The preparation method of the aluminum alloy containing recycled aluminum is specifically as follows: Step 1: Prepare 1.0 ton of primary A356 aluminum liquid in a tundish.

[0041] Step 2: Pour 50% recycled aluminum into the tundish, stir evenly after melting, and skim the surface scum with a ladle.

[0042] Step 3: Weigh the Al-Ce master alloy and Al-La master alloy according to the target alloy composition to obtain the weighed Al-20La and Al-20Ce master alloys. Add the weighed Al-20La and Al-20Ce master alloys to the tundish according to the set ratio, stir for 5 - 10 minutes, then degas, and then sprinkle with a refining agent to remove impurities, thus completing the preparation of the aluminum alloy.

[0043] Further, prepare the wheel hub: After skimming the slag, transfer the tundish to the front of the holding furnace of the die-casting machine, pour in the molten aluminum, start the low-pressure casting machine to complete the low-pressure casting, and obtain the cast wheel hub. Inspect the quality of the cast wheel hub, reject the non-conforming wheel hubs, and obtain qualified wheel hubs. Perform heat treatment on the qualified wheel hubs to complete the casting and obtain the wheel hubs.

[0044] The metallographic structure pictures obtained by sampling the outer rim of the said wheel hub are as Figure 2 shown.

[0045] In a specific embodiment, the quality inspection in Step 5 includes checking whether there are obvious defects on the surface of the wheel hub and sending the wheel hub into the X-ray room for flaw detection. Example

[0046] An aluminum alloy containing recycled aluminum, the mass percentages of its various components are selected as: Si 7.4%, Mg 0.32%, Ti 0.10%, Fe 0.089%, Sr 0.012%, La 0.048%, Sm 0.050%, and the balance is Al.

[0047] The preparation method of the said aluminum alloy containing recycled aluminum is specifically as follows: Step 1: Prepare 1.0 ton of primary A356 molten aluminum in the tundish.

[0048] Step 2: Charge 70% of recycled aluminum into the tundish, melt and stir evenly, and skim the surface scum with a ladle.

[0049] Step 3: Weigh the Al-La master alloy and Al-Sm master alloy according to the target alloy composition to obtain the weighed Al-20La and Al-20Sm master alloys. Add the weighed Al-20La and Al-20Sm master alloys to the tundish according to the set ratio, stir for 5 - 10 minutes, then degas, and then sprinkle with a refining agent to remove impurities, thus completing the preparation of the aluminum alloy.

[0050] Further, prepare the wheel hub: After skimming the slag, transfer the tundish to the front of the holding furnace of the die-casting machine, pour in the molten aluminum, start the low-pressure casting machine to complete the low-pressure casting, and obtain the cast wheel hub. Inspect the quality of the cast wheel hub, reject the non-conforming wheel hubs, and obtain qualified wheel hubs. Perform heat treatment on the qualified wheel hubs to complete the casting and obtain the wheel hubs.

[0051] The metallographic structure pictures obtained by sampling the outer rim of the wheel hub are as Figure 2 shown.

[0052] In a specific embodiment, the quality inspection in step 5 includes checking whether there are obvious defects on the surface of the wheel hub and sending the wheel hub into an X-ray chamber for flaw detection.

[0053] In the above embodiment, the specific component specifications of the wheel hub are shown in Table 1: Composition (wt.%) Average yield strength (MPa) Average elongation (%) 0.045La + 0.048Ce 192.15 13.7 0.061La + 0.032Ce 197.63 14.8 0.048La + 0.050Sm 196.58 14.5 Table 1 It can be seen that the yield strength of the wheel hub in the present invention is ≥180 MPa and the elongation is ≥13%.

[0054] The present invention proposes to prepare aluminum alloy by adding 50-70% recycled aluminum into primary A356 for the production of wheel hubs, which reduces production costs and carbon emissions. And by adding mixed rare earth Re (La, Ce and Sm) to form AlFeSiRe phase to control the formation of coarse iron phase in the structure, and optimize and screen out the best proportion of mixed rare earth. Compared with the original aluminum material, the rare earth aluminum alloy wheel hub (containing recycled aluminum) prepared by low-pressure casting has its mechanical properties not reduced in the T6 state.

[0055] As is known by common technical knowledge, the present invention can be implemented by other embodiments without departing from its spiritual essence or essential features. Therefore, the above-disclosed embodiments are illustrative in all aspects and not exclusive. All changes within the scope of the present invention or equivalent to the present invention are encompassed by the present invention.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific embodiments of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement without departing from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. An aluminum alloy containing recycled aluminum, characterized in that, The mass percentages of the components of the aluminum alloy are as follows: Si 6.8 - 7.4%, Mg 0.3 - 0.35%, Ti 0.1 - 0.15%, Fe ≤0.12%, Sr 0.01 - 0.02%, Mn < 0.05%, RE 0.05 - 0.1%, impurity elements ≤0.3%, and the balance is Al.

2. The aluminum alloy containing recycled aluminum according to claim 1, characterized in that, The specific RE is La and Ce, and the mass ratio is 1:

1.

3. The aluminum alloy containing recycled aluminum according to claim 1, wherein, The specific RE is La and Ce, and the mass ratio is 2:

1.

4. The aluminum alloy containing recycled aluminum according to claim 1, characterized in that, The specific RE is La and Sm, and the mass ratio is 4:

1.

5. A preparation method of an aluminum alloy containing recycled aluminum, characterized in that, It includes the following steps; Step 1, place molten aluminum in the tundish; Step 2, add recycled aluminum to the molten aluminum, stir evenly after melting; Step 3, weigh the Al-Re master alloy according to the target composition, add the weighed Al-Re master alloy to the tundish, stir and then degas, and sprinkle a refining agent on the degassed molten aluminum to obtain the aluminum alloy containing recycled aluminum described in any one of claims 1 - 4.

6. The preparation method of an aluminum alloy containing recycled aluminum according to claim 5, characterized in that, The molten aluminum in Step 1 is primary A356 molten aluminum.

7. The preparation method of an aluminum alloy containing recycled aluminum according to claim 5, characterized in that, The mass of the recycled aluminum in Step 2 accounts for 50 - 70% of the molten aluminum in Step 1.

8. The preparation method of an aluminum alloy containing recycled aluminum according to claim 5, characterized in that, The Al-Re master alloy in Step 3 includes Al-Ce master alloy, Al-La master alloy and Al-Sm master alloy.

9. A hub, characterized in that, The wheel hub is prepared from an aluminum alloy containing recycled aluminum described in any one of claims 1 - 4.

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