High-hardness cast aluminum alloy containing element strontium and preparation method of high-hardness cast aluminum alloy

Abstract

The invention provides a high-hardness cast aluminum alloy containing element strontium and a preparation method of the high-hardness cast aluminum alloy, and belongs to the technical field of aluminum alloy materials. By adding Si, the strength and hardness of the alloy can be improved, the heat treatment effect is improved, and meanwhile the wear resistance and heat resistance of the alloy can be improved; mg is added, so that the strength and the corrosion resistance of the alloy can be improved, and meanwhile, the processability of the alloy can be improved; cu and Mn are added, so that the strength and corrosion resistance of the alloy can be improved; the hardness and strength of the alloy can be improved by adding Fe; and Sr is added, so that the original as-cast structure of the aluminum alloy is refined, a better structure is obtained, and the hardness of the T6-state cast alloy is improved. The result of the embodiment shows that the room-temperature hardness, the wear resistance and the elongation at break of the high-hardness cast aluminum alloy containing the element strontium are obviously higher than those of A356 aluminum alloy and ZL101.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy materials, and in particular to a high-hardness cast aluminum alloy containing the element strontium and a preparation method thereof. Background Art

[0002] Cast aluminum alloys, such as A356 alloy, are aluminum alloys with high strength and good heat resistance. Its main element composition is close to China's aluminum alloy grade ZL101, and it is widely used in aerospace, automobile manufacturing, engineering and construction. The chemical composition of A356 alloy mainly includes aluminum (Al), silicon (Si), magnesium (Mg), copper (Cu), manganese (Mn) and iron (Fe). However, at room temperature, the average hardness of the cast A356 aluminum alloy is 55HB, in which the α-Al phase has a coarse grain size and a disorderly distribution, and the eutectic Si phase precipitated at the grain boundary has a segregation and aggregation phenomenon, resulting in a lower hardness of the cast A356 aluminum alloy.

[0003] Therefore, there is an urgent need to provide a high-hardness cast aluminum alloy to solve the problem of low hardness of the cast aluminum alloy. Summary of the invention

[0004] The object of the present invention is to provide a high-hardness cast aluminum alloy containing the element strontium and a preparation method thereof.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The invention provides a high-hardness cast aluminum alloy containing the element strontium, which comprises, by mass percentage, 6.5-7.5% Si, ≤0.35% Mg, ≤0.2% Fe, ≤0.2% Cu, ≤0.2% Zn, ≤0.1% Mn, ≤0.1% Ti, ≤0.2% Sr, and the balance Al.

[0007] Preferably, the high hardness cast aluminum alloy containing strontium element comprises, by mass percentage: Si 6.6-7%, Mg 0.25-0.35%, Fe 0.1-0.15%, Cu 0.1-0.15%, Zn 0.03-0.07%, Mn 0.04-0.07%, Ti 0.13-0.19%, Sr 0.03-0.07% and the balance Al.

[0008] Preferably, the high hardness cast aluminum alloy containing strontium element comprises, by mass percentage, 6.6% Si, 0.25% Mg, 0.1% Fe, 0.12% Cu, 0.05% Zn, 0.04% Mn, 0.13% Ti, 0.05% Sr and the balance Al.

[0009] Preferably, the high hardness cast aluminum alloy containing strontium element comprises, by mass percentage, 7% Si, 0.15% Mg, 0.15% Fe, 0.1% Cu, 0.07% Zn, 0.05% Mn, 0.17% Ti, 0.03% Sr and the balance Al.

[0010] Preferably, the high hardness cast aluminum alloy containing strontium element comprises, by mass percentage, 6.8% Si, 0.29% Mg, 0.14% Fe, 0.15% Cu, 0.03% Zn, 0.07% Mn, 0.19% Ti, 0.07% Sr and the balance Al.

[0011] The present invention also provides a method for preparing the high-hardness cast aluminum alloy containing the element strontium described in the above technical solution, comprising: vacuum melting the alloy raw materials and then casting to obtain a high-hardness cast aluminum alloy containing the element strontium in a casting.

[0012] Preferably, the vacuum degree of the vacuum melting is 6 to 7×10 -3 Pa.

[0013] Preferably, the insulation temperature of the vacuum melting is 720-740° C.; the insulation time of the vacuum melting is 1-5 min.

[0014] Preferably, the casting speed is 4-5 kg / S.

[0015] Preferably, the casting further includes cooling; the cooling method is air cooling, and the cooling rate is 40-50°C / min.

[0016] The present invention provides a high-hardness cast aluminum alloy containing strontium, which comprises, by mass percentage, Si 6.5-7.5%, Mg≤0.35%, Fe≤0.2%, Cu≤0.2%, Zn≤0.1%, Mn≤0.1%, Ti≤0.2%, Sr≤0.1% and the balance Al. The present invention can improve the strength and hardness of the alloy by adding Si, increase the effect of heat treatment, and also improve the wear resistance and heat resistance of the alloy; adding Mg can improve the strength and corrosion resistance of the alloy, and also improve the processing performance of the alloy; adding Cu and Mn can improve the strength and corrosion resistance of the alloy; adding Fe can improve the hardness and strength of the alloy; adding Sr refines the original cast structure of the aluminum alloy, obtains a better structure, and improves the hardness of the T6 state cast alloy. The results of the embodiment show that the room temperature hardness, wear resistance and elongation at break of the high-hardness cast aluminum alloy containing strontium provided by the present invention are significantly higher than those of A356 aluminum alloy and ZL101. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1The microstructure of the high-hardness cast aluminum alloy containing strontium provided in Example 1 of the present invention;

[0018] Figure 2 The microstructure of the A356 aluminum alloy provided in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The invention provides a high-hardness cast aluminum alloy containing the element strontium, which comprises, by mass percentage, 6.5-7.5% Si, ≤0.35% Mg, ≤0.2% Fe, ≤0.2% Cu, ≤0.2% Zn, ≤0.1% Mn, ≤0.1% Ti, ≤0.2% Sr, and the balance Al.

[0020] The high-hardness cast aluminum alloy containing strontium provided by the present invention includes Si6.5-7.5%, preferably 6.6-7%, by mass percentage. As an embodiment of the present invention, the mass percentage of Si can be 6.6%, 6.8% or 7%. The present invention can improve the strength and hardness of the alloy by adding Si, increase the effect of heat treatment, and also improve the wear resistance and heat resistance of the alloy.

[0021] In terms of mass percentage, the high-hardness cast aluminum alloy containing strontium provided by the present invention includes Mg≤0.35%, preferably 0.25-0.35%. As an embodiment of the present invention, the mass percentage of Mg can be 0.25%, 0.29% or 0.35%. The present invention can improve the strength and corrosion resistance of the alloy by adding Mg, and can also improve the processing performance of the alloy.

[0022] In terms of mass percentage, the high-hardness cast aluminum alloy containing strontium provided by the present invention includes Fe≤0.2%, preferably 0.1-0.15%. As an embodiment of the present invention, the mass percentage of Fe can be 0.1%, 0.14% or 0.15%. The present invention can improve the hardness and strength of the alloy by adding Fe.

[0023] In terms of mass percentage, the high-hardness cast aluminum alloy containing strontium provided by the present invention includes Cu≤0.2%, preferably 0.1-0.15%. As an embodiment of the present invention, the mass percentage of Cu can be 0.1%, 0.12% or 0.15%. The strength and corrosion resistance of the alloy can be improved by adding Cu.

[0024] In terms of mass percentage, the high-hardness cast aluminum alloy containing strontium provided by the present invention includes Zn≤0.1%, preferably 0.03-0.07%. As an embodiment of the present invention, the mass percentage of Zn can be 0.03%, 0.05% or 0.07%. The present invention can improve the strength and corrosion resistance of the alloy by adding Zn.

[0025] In terms of mass percentage, the high-hardness cast aluminum alloy containing strontium provided by the present invention includes Mn≤0.1%, preferably 0.04-0.07%. As an embodiment of the present invention, the mass percentage of Mn can be 0.04%, 0.05% or 0.07%. The present invention can improve the strength and corrosion resistance of the alloy by adding Mn.

[0026] The high-hardness cast aluminum alloy containing strontium provided by the present invention includes Ti≤0.2%, preferably 0.13-0.19%. As an embodiment of the present invention, the mass percentage of Ti can be 0.13%, 0.17% or 0.19%. The present invention can form an Al3Ti phase that is easy to precipitate with aluminum by adding Ti, which can effectively strengthen the aluminum matrix and improve its strength and rigidity.

[0027] In terms of mass percentage, the high-hardness cast aluminum alloy containing strontium provided by the present invention includes Sr≤0.1%, preferably 0.03-0.07%. As an embodiment of the present invention, the mass percentage of Sr can be 0.03%, 0.05% or 0.07%. By adding Sr, the original cast structure of the aluminum alloy can be refined, a better structure can be obtained, and the hardness of the T6 state cast alloy can be improved.

[0028] Measured by mass percentage, the high hardness cast aluminum alloy containing element strontium provided by the present invention includes a balance of Al.

[0029] The invention can improve the strength and hardness of the alloy by controlling the type and amount of each component in the aluminum alloy.

[0030] The present invention also provides a method for preparing the high-hardness cast aluminum alloy containing the element strontium described in the above technical solution, comprising: vacuum melting the alloy raw materials and then casting to obtain a high-hardness cast aluminum alloy containing the element strontium in a casting.

[0031] In the present invention, the alloy raw materials preferably include Si, Mg, Fe, Cu, Zn, Mn, Ti, Sr and Al. In the present invention, the purity of the alloy raw materials is preferably 98% to 99% independently. The present invention has no particular limitation on the specific source of the alloy raw materials, and commercial products well known to those skilled in the art can be used.

[0032] In the present invention, the vacuum degree of the vacuum melting is preferably 6 to 7×10 -3 Pa, more preferably 6.67×10 - 3Pa; the atmosphere of the vacuum melting is preferably argon; the insulation temperature of the vacuum melting is preferably 720-740°C, more preferably 730°C; the insulation time of the vacuum melting is preferably 1-5 minutes, more preferably 2-5 minutes. The present invention has no special limitation on the device of the vacuum melting, and any conventional vacuum melting device can be used. The present invention controls the parameters of the vacuum melting within the above range, which can ensure that the added alloy elements are fully melted.

[0033] In the present invention, the vacuum melting method preferably includes: heating the raw materials of Si, Mg, Fe, Cu, Zn, Mn, Ti and Al to the insulation temperature of vacuum melting in a vacuum melting device, keeping the temperature for 1 to 5 minutes, preferably keeping the temperature for 5 minutes, adding the raw material of Sr, and then continuing to keep the temperature for 5 to 10 minutes, preferably keeping the temperature for 10 minutes, to obtain a mixed melt; adding a refining agent to the mixed melt, refining and slagging, to obtain a casting liquid.

[0034] In the present invention, the refining agent is preferably an inorganic refining agent, and the inorganic refining agent preferably includes NaCl, NaCl-KCl or NaCl-KCl-Na3AlF6. In an embodiment of the present invention, the NaCl-KCl is composed of NaCl and KCl, and the mass ratio of NaCl to KCl in the NaCl-KCl can be 7:2. In an embodiment of the present invention, the NaCl-KCl-Na3AlF6 is composed of NaCl, KCl and Na3AlF6, and the mass ratio of NaCl, KCl and Na3AlF6 in the NaCl-KCl-Na3AlF6 can be 10:13:11.

[0035] In the present invention, the inorganic refining agent preferably accounts for 0.2-0.4% by mass of the mixed melt, and more preferably 0.3%. In the present invention, impurities can be removed by adding the refining agent for refining.

[0036] In the present invention, the refining time is preferably 8 to 12 minutes, more preferably 10 minutes.

[0037] The present invention has no special limitation on the refining and slag skimming operation methods, and conventional refining and slag skimming operation methods may be used.

[0038] The present invention preferably cools the molten metal obtained by the refining and slagging to obtain a casting liquid. In the present invention, the temperature of the casting liquid is preferably 700-720° C., more preferably 710° C. The present invention is more conducive to controlling the alloy to have a better microstructure after casting by cooling.

[0039] In the present invention, the casting method is preferably: casting the casting liquid into a preheated mold.

[0040] In the present invention, the casting speed is preferably 4-6 kg / S, more preferably 5 kg / S. In the present invention, the temperature of the preheating mold is preferably 150-250° C., more preferably 200° C. The present invention controls the casting speed and the temperature of the preheating mold within the above range, which is more conducive to improving production efficiency and alloy quality.

[0041] In the present invention, cooling is further performed after casting; the cooling method is air cooling, and the cooling rate is preferably 40-50°C / min, more preferably 50°C / min. The present invention adopts the above cooling method, which is more conducive to improving the uniformity of the alloy structure.

[0042] The method provided by the present invention is simple to operate, can improve the uniformity of alloy composition and structure, and is beneficial to improving the structural uniformity of the alloy.

[0043] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Example 1

[0045] A high-hardness cast aluminum alloy containing the element strontium, which comprises, by mass percentage, 6.5% Si, 0.25% Mg, 0.1% Fe, 0.12% Cu, 0.05% Zn, 0.04% Mn, 0.13% Ti, 0.03% Sr and the balance Al;

[0046] The preparation method of the high-hardness cast aluminum alloy containing strontium element is as follows: the alloy is smelted by vacuum metallurgy with a vacuum degree of 6.67×10 -3pa, argon protection, heat the alloy raw materials of Si, Mg, Fe, Cu, Zn, Mn, Ti and Al to 730℃, keep warm for 5 minutes, then add 0.03% Sr, keep warm for 10 minutes and stir, add inorganic salt refining agent (NaCl-KCl-Na3AlF6, wherein the mass ratio of NaCl, KCl and Na3AlF6 is 10:13:11, and the amount is 0.3% of the weight of the aluminum liquid) and refine for 10 minutes, let it stand for 5 minutes, and then remove the slag. When removing the slag, first ultrasonically stir the melt for 2 minutes to make the slag fully float, and then use a high-temperature resistant ceramic slag spoon to remove the slag, and repeat this operation three to five times to make the solution surface free of slag. After slag removal, the temperature is lowered to 710℃, kept warm for 5 minutes, and then cast. The casting mold is made of cast steel, the casting speed is 5kg / S, the cooling method is air cooling, the cooling rate is 50℃ / min, and the mold needs to be preheated at 200℃ for no less than 2h.

[0047] Example 2

[0048] A high-hardness cast aluminum alloy containing the element strontium, which comprises, by mass percentage, 7% Si, 0.35% Mg, 0.15% Fe, 0.1% Cu, 0.07% Zn, 0.05% Mn, 0.17% Ti, 0.05% Sr and the balance Al;

[0049] The preparation method of the high-hardness cast aluminum alloy containing strontium element is as follows: the alloy is smelted by vacuum metallurgy with a vacuum degree of 6.67×10 -3 pa, argon protection, heat the alloy raw materials of Si, Mg, Fe, Cu, Zn, Mn, Ti and Al to 730℃, keep warm for 5 minutes, then add 0.05% Sr, keep warm for 10 minutes and stir, add inorganic salt refining agent (NaCl-KCl-Na3AlF6, wherein the mass ratio of NaCl, KCl and Na3AlF6 is 10:13:11, and the amount is 0.3% of the weight of the aluminum liquid) and refine for 10 minutes, let it stand for 5 minutes, and then remove the slag. When removing the slag, first ultrasonically stir the melt for 2 minutes to make the slag fully float, and then use a high-temperature resistant ceramic slag spoon to remove the slag, and repeat this operation three to five times to make the solution surface free of slag. After slag removal, the temperature is lowered to 710℃, kept warm for 5 minutes, and then cast. The casting mold is made of cast steel, the casting speed is 5kg / S, the cooling method is air cooling, the cooling rate is 50℃ / min, and the mold needs to be preheated at 200℃ for no less than 2h.

[0050] Example 3

[0051] A high-hardness cast aluminum alloy containing the element strontium, which comprises, by mass percentage, 6.8% Si, 0.29% Mg, 0.14% Fe, 0.15% Cu, 0.03% Zn, 0.07% Mn, 0.19% Ti, 0.07% Sr and the balance Al;

[0052] The preparation method of the high-hardness cast aluminum alloy containing strontium element is as follows: the alloy is smelted by vacuum metallurgy with a vacuum degree of 6.67×10 -3 pa, argon protection, heat the alloy raw materials of Si, Mg, Fe, Cu, Zn, Mn, Ti and Al to 730℃, keep warm for 5 minutes, then add 0.07% Sr, keep warm for 10 minutes and stir, add inorganic salt refining agent (NaCl-KCl-Na3AlF6, wherein the mass ratio of NaCl, KCl and Na3AlF6 is 10:13:11, and the amount is 0.3% of the weight of the aluminum liquid) and refine for 10 minutes, let it stand for 5 minutes, and then remove the slag. When removing the slag, first ultrasonically stir the melt for 2 minutes to make the slag fully float, and then use a high-temperature resistant ceramic slag spoon to remove the slag, and repeat this operation three to five times to make the solution surface free of slag. After slag removal, the temperature is lowered to 710℃, kept warm for 5 minutes, and then cast. The casting mold is made of cast steel, the casting speed is 5kg / S, the cooling method is air cooling, the cooling rate is 50℃ / min, and the mold needs to be preheated at 200℃ for no less than 2h.

[0053] Comparative Example 1

[0054] The compositions of commercially available aluminum alloys A356 aluminum alloy and ZL101 aluminum alloy are shown in Table 1:

[0055] Table 1 Composition of commercially available aluminum alloys

[0056] alloy Si Mg Fe Cu Zn Mn Ti Al A356 6.5～7.5％ ≤0.15％ ≤0.2％ ≤0.2％ ≤0.1％ ≤0.1％ ≤0.2％ margin ZL101 6.5～7.5％ 0.25～0.45％ ≤0.9％ ≤0.2％ ≤0.3％ ≤0.35％ ≤0.25 margin

[0057] Test Case

[0058] (1) The microstructure of the high-hardness cast aluminum alloy containing strontium provided in Example 1 is as follows: Figure 1 As shown, the microstructure of the A356 aluminum alloy provided in Comparative Example 1 is as follows Figure 2 As shown. Figure 1 and Figure 2 It can be seen that the high-hardness cast aluminum alloy containing strontium element provided by the present invention has a better organizational structure.

[0059] (2) The hardness, elongation at break, wear rate and corrosion depth of the high hardness cast aluminum alloy containing strontium provided in Examples 1 to 3 of the present invention and the T6 alloy of the aluminum alloy of the comparative example are shown in Table 2:

[0060] Table 2 Performance test results of T6 alloys of different aluminum alloys

[0061] alloy Hardness (HB) Elongation at break Wear rate (mg / min) Corrosion depth (μm) A356 80 3.5％ 8 305 ZL101 81 3％ 8.3 301 Example 1 88 7％ 7.4 216 Example 2 93 9％ 6.5 192 Example 3 84 8％ 7.6 203

[0062] It can be seen from Table 2 that the hardness, elongation at break, wear rate and corrosion depth of the high-hardness cast aluminum alloy containing strontium provided by the present invention are better than those of the commercially available aluminum alloys A356 aluminum alloy and ZL101 aluminum alloy. This is because the present invention refines the original cast structure of the aluminum alloy by adding the Sr element, obtains a better structure, and improves the hardness, elongation at break, wear rate and corrosion depth of the T6 state cast alloy.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-hardness cast aluminum alloy containing the element strontium, comprising, by mass percentage: Si 6.5-7.5%, Mg≤0.35%, Fe≤0.2%, Cu≤0.2%, Zn≤0.1%, Mn≤0.1%, Ti≤0.2%, Sr≤0.1% and the balance Al.

2. The high-hardness cast aluminum alloy containing strontium according to claim 1, characterized in that: Calculated by mass percentage, the high-hardness cast aluminum alloy containing strontium element includes: Si 6.6-7%, Mg 0.25-0.35%, Fe 0.1-0.15%, Cu 0.1-0.15%, Zn 0.03-0.07%, Mn 0.04-0.07%, Ti 0.13-0.19%, Sr 0.03-0.07% and the balance Al.

3. The high-hardness cast aluminum alloy containing strontium according to claim 1, characterized in that: Calculated by mass percentage, the high-hardness cast aluminum alloy containing strontium element includes: Si 6.6%, Mg 0.25%, Fe 0.1%, Cu 0.12%, Zn 0.05%, Mn 0.04%, Ti 0.13%, Sr 0.05% and the balance Al.

4. The high-hardness cast aluminum alloy containing strontium according to claim 1, characterized in that: Calculated by mass percentage, the high-hardness cast aluminum alloy containing strontium element includes: Si 7%, Mg 0.15%, Fe 0.15%, Cu 0.1%, Zn 0.07%, Mn 0.05%, Ti 0.17%, Sr 0.03% and the balance Al.

5. The high-hardness cast aluminum alloy containing strontium element according to claim 1, characterized in that: Calculated by mass percentage, the high-hardness cast aluminum alloy containing strontium element includes: Si 6.8%, Mg 0.29%, Fe 0.14%, Cu 0.15%, Zn 0.03%, Mn 0.07%, Ti 0.19%, Sr 0.07% and the balance Al.

6. The method for preparing the high-hardness cast aluminum alloy containing strontium as claimed in any one of claims 1 to 5, comprising: The alloy raw materials are vacuum melted and then cast to obtain a high-hardness cast aluminum alloy containing strontium in a casting.

7. The preparation method according to claim 6, characterized in that: The vacuum degree of the vacuum melting is 6 to 7 × 10 - 3 Pa.

8. The preparation method according to claim 6, characterized in that: The insulation temperature of the vacuum melting is 720-740° C.; the insulation time of the vacuum melting is 1-5 minutes.

9. The preparation method according to claim 6, characterized in that: The casting speed is 4-5 kg / S.

10. The preparation method according to claim 6, characterized in that: The method further includes cooling after casting; the cooling method is air cooling, and the cooling rate is 40-50°C / min.

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