A high temperature resistant and thermal crack resistant cast aluminum alloy and preparation method thereof

Abstract

The present invention provides a high temperature resistant and hot crack resistant casting aluminum alloy and a preparation method thereof, which solves the technical problems that the mechanical properties of the existing aluminum alloy cannot meet the requirements of high temperature conditions, and the hot crack resistance and the forming performance are poor. The casting aluminum alloy of the present invention contains the following components in mass percentage: Cu content is 5% to 10%, Er content is 0.3% to 5%, Mn content is 0.3% to 2%, Zr content is 0.1% to 1.5%, Ti content is 0.05% to 0.35%, Fe content is ≤0.5%, Si content is ≤0.5%, the total amount of other elements is ≤0.2%, and the balance is Al. The present invention also discloses a preparation method of the above casting aluminum alloy, according to the casting aluminum alloy element ratio, the required proportion of copper-containing material, erbium-containing material, manganese-containing material, zirconium-containing material, titanium-containing material, and aluminum-containing material are weighed, the copper-containing material, erbium-containing material, manganese-containing material, zirconium-containing material, and aluminum-containing material are smelted, and after smelting, titanium-containing material is added for refinement treatment, and then casting molding, solid solution treatment, and aging treatment are performed to obtain the casting aluminum alloy. It can be widely used in the field of metal materials.

Description

Technical Field

[0001] The present application relates to the field of metal materials, and in particular to a high temperature resistant and thermal crack resistant cast aluminum alloy and a preparation method thereof. Background Art

[0002] Aluminum alloy is a lightweight metal with good electrical and thermal conductivity, corrosion resistance, mechanical properties, machinability, formability and recyclability. In recent years, the application of new energy vehicles, especially hydrogen engines, requires higher operating temperatures and working pressures. At the same time, with the rapid development of the aerospace industry, the flight speed of aviation and spacecraft continues to increase, and the friction between the aircraft and the atmosphere generates a lot of heat, causing the external temperature of the aircraft to continue to rise, which puts higher requirements on the heat resistance of aviation and spacecraft structural materials. However, the existing casting aluminum alloys are difficult to meet this demand, and the industry has put forward higher requirements on the working temperature of aluminum alloys.

[0003] At present, high temperature resistant casting aluminum alloys can be roughly divided into two categories. One is based on aluminum silicon, with the addition of copper, zirconium, scandium and other elements. The working temperature of this type of alloy is generally limited to less than 200℃. The other is developed with aluminum copper as the basic components. This type of alloy can work at higher temperatures. The main chemical composition of the relatively successful LA205A aluminum alloy is (4.6~5.3)wt.%Cu, 1.5wt.%Mg, (0.3~0.5)wt.%Mn, (0.05~0.2)wt.%Zr, (0.15~0.35)wt.%Ti, (0.15~0.35)wt.%Cd, Al balance; its tensile strength at 300℃ is 170MPa and its elongation is 3.5%. Another widely used A201 aluminum alloy has the main components of (4.0~5.0)wt.%Cu, (0.15~0.35)wt.%Mg, (0.4~1.0)wt.%Ag, (0.2~0.4)wt.%Mn, (0.05~0.2)wt.%Zr, (0.15~0.35)wt.%Ti, Al as balance; its tensile strength at 300℃ is 140MPa and its elongation is 12%.

[0004] However, there are two main problems with the above materials. First, it is still difficult to meet the current requirements for the mechanical properties of the materials under high temperature conditions. Second, the high temperature performance of the alloy is mainly obtained by the addition of Cu elements. The biggest problem is the poor thermal cracking resistance and poor forming performance of the alloy. Therefore, it is very urgent to develop an aluminum alloy with high temperature performance and thermal cracking resistance. Summary of the invention

[0005] The purpose of the present invention is to solve the above technical problems and provide a high temperature resistant and thermal crack resistant cast aluminum alloy and a preparation method thereof, so that its mechanical properties meet the requirements of high temperature conditions, improve the thermal crack resistance, and improve the forming performance of the alloy.

[0006] To this end, the present invention provides a high temperature resistant and thermal crack resistant cast aluminum alloy, comprising the following components in percentage by mass:

[0007] The Cu content is 5% to 10%, the Er content is 0.3% to 5%, the Mn content is 0.3% to 2%, the Zr content is 0.1% to 1.5%, the Ti content is 0.05% to 0.35%, the Fe content is ≤0.5%, the Si content is ≤0.5%, the total amount of other elements is ≤0.2%, and the balance is Al.

[0008] Or, containing the following components in percentage by weight:

[0009] The Cu content is 6% to 8%, the Er content is 0.8% to 3%, the Mn content is 0.3% to 1.5%, the Zr content is 0.1% to 1.5%, the Ti content is 0.05% to 0.35%, the Fe content is ≤0.5%, the Si content is ≤0.5%, the total amount of other elements is ≤0.2%, and the balance is Al.

[0010] Preferably, in the cast aluminum alloy, the weight ratio of Er to Cu elements is (0.05-0.84):1.

[0011] The present invention also provides a method for preparing the high temperature resistant and thermal cracking resistant cast aluminum alloy as described in any one of the above, comprising the following steps:

[0012] According to the ratio of elements in the cast aluminum alloy, the required proportion of copper-containing material, erbium-containing material, manganese-containing material, zirconium-containing material, titanium-containing material and aluminum-containing material are weighed, and the copper-containing material, erbium-containing material, manganese-containing material, zirconium-containing material and aluminum-containing material are smelted. After smelting, titanium-containing material is added for refinement treatment, and then casting is carried out, and then one or more stages of solid solution treatment and aging treatment are carried out to obtain the cast aluminum alloy.

[0013] Preferably, the copper-containing material is added in the form of pure copper ingots or Al-Cu master alloys, the erbium-containing material is added in the form of Al-Er master alloys, the manganese-containing material is added in the form of Al-Mn master alloys, the zirconium-containing material is added in the form of Al-Zr master alloys, the titanium-containing material is added in the form of Al-Ti or Al-Ti-B master alloys, and the aluminum-containing material is added in the form of pure aluminum ingots.

[0014] Preferably, the melting temperature is 750°C to 800°C, the refining temperature is 700°C to 750°C, and the casting temperature is 700°C to 730°C.

[0015] Preferably, after the refinement treatment is completed, the temperature is lowered to 700° C. to 730° C. for melt purification and inert gas degassing and refining, and after standing for 2 min to 30 min, the slag is removed and casting is performed.

[0016] Preferably, the solution treatment adopts a one-stage solution treatment process, and the aging treatment adopts a one-stage aging treatment process: first, a solution heat treatment is performed in a temperature range of 450°C to 550°C for no more than 35 hours, and then an aging treatment is performed in a temperature range of 150°C to 220°C for no more than 40 hours.

[0017] Preferably, the solution treatment adopts a two-stage solution heat treatment process: first, a primary solution heat treatment is performed in a temperature range of 440°C to 510°C for no more than 15 hours, and then a secondary solution heat treatment is performed in a temperature range of 510°C to 550°C for no more than 20 hours.

[0018] Preferably, the solution treatment adopts a three-stage solution heat treatment process: keeping at 440°C to 480°C for 0.5h to 10h, then heating to 480°C to 510°C for 0.5h to 15h, and finally heating to 510°C to 550°C for 0.5h to 10h.

[0019] Preferably, the aging treatment adopts a two-stage aging treatment process: first, keep warm at 150°C to 165°C for 1h to 16h, and then keep warm at 180°C to 200°C for 6h to 24h.

[0020] Preferably, the aging treatment adopts a three-stage aging treatment process: first keep warm at 150°C to 165°C for 1h to 10h, then keep warm at 170°C to 190°C for 6h to 15h, and finally increase the temperature to 190°C to 220°C and keep warm for 8h to 15h.

[0021] The present invention provides a high temperature resistant and thermal crack resistant cast aluminum alloy and a preparation method thereof, which mainly has the following beneficial effects:

[0022] (1) The present invention optimizes the alloy composition so that the alloy has good thermal cracking resistance; by optimizing the heat treatment process, a large number of fine dispersed strengthening phases can be obtained, which has good mechanical properties and excellent high-temperature mechanical properties;

[0023] (2) The cast aluminum alloy of the present invention obtains a tensile strength of ≥210 MPa and an elongation of ≥7% at a high temperature of 300°C by adjusting the content, ratio and existence form of Er and Cu elements in the alloy;

[0024] (3) The cast aluminum alloy described in the present invention adjusts the solidus temperature of the alloy through the Er element, shortens the solidification temperature range of the alloy, and improves the thermal cracking resistance of the alloy. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application is further described in detail in conjunction with the embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. The methods used in the present invention are conventional methods unless otherwise specified; the raw materials and devices used are conventional commercial products unless otherwise specified.

[0026] The embodiment of the present invention provides a high temperature resistant and thermal crack resistant cast aluminum alloy, comprising the following components in percentage by mass:

[0027] The Cu content is 5% to 10%, the Er content is 0.3% to 5%, the Mn content is 0.3% to 2%, the Zr content is 0.1% to 1.5%, the Ti content is 0.05% to 0.35%, the Fe content is ≤0.5%, the Si content is ≤0.5%, the total amount of other elements is ≤0.2%, and the balance is Al.

[0028] In some embodiments, the cast aluminum alloy contains the following components in percentage by weight:

[0029] The Cu content is 6% to 8%, the Er content is 0.8% to 3%, the Mn content is 0.3% to 1.5%, the Zr content is 0.1% to 1.5%, the Ti content is 0.05% to 0.35%, the Fe content is ≤0.5%, the Si content is ≤0.5%, the total amount of other elements is ≤0.2%, and the balance is Al.

[0030] In some embodiments, in the cast aluminum alloy, the weight ratio of Er to Cu elements is (0.05-0.84):1.

[0031] It should be noted that, among the elements involved in the present invention, their corresponding contents are obtained through specific experimental tests and principle analysis. When the content of each element is within the above range, a high-temperature resistant and thermal crack resistant cast aluminum alloy with excellent comprehensive performance can be obtained, and its tensile strength at a high temperature of 300°C is ≥210MPa, and its elongation is ≥7%. At the same time, it has good thermal crack resistance and can meet industrial needs.

[0032] In the description of the present invention, "other elements" refer to other elements other than the elements in the cast aluminum alloy components provided by the present invention, which may be metal elements or non-metal elements. Generally, "other elements" exist as impurities, generally derived from impurities contained in the raw materials when preparing the cast aluminum alloy. The cast aluminum alloy provided by the present invention is allowed to maintain higher mechanical properties in the presence of a certain amount of other elements, for example, the total amount of other elements is ≤0.2%. Too many other elements can easily lead to problems such as decreased elongation, product cracking, and poor corrosion resistance in the cast aluminum alloy.

[0033] The embodiment of the present invention further provides a method for preparing the high temperature resistant and thermal cracking resistant cast aluminum alloy as described in any one of the above, comprising the following steps:

[0034] According to the ratio of elements in the cast aluminum alloy, the required proportion of copper-containing material, erbium-containing material, manganese-containing material, zirconium-containing material, titanium-containing material and aluminum-containing material are weighed, and the copper-containing material, erbium-containing material, manganese-containing material, zirconium-containing material and aluminum-containing material are smelted. After smelting, titanium-containing material is added for refinement treatment, and then casting is carried out, and then one or more stages of solid solution treatment and aging treatment are carried out to obtain the cast aluminum alloy.

[0035] The copper-containing material, erbium-containing material, manganese-containing material, zirconium-containing material, titanium-containing material, and aluminum-containing material can be materials that can provide the various elements required for preparing the cast aluminum alloy of the present invention, and can be alloys or pure metals containing the above elements, as long as the composition of the cast aluminum alloy obtained after smelting the added magnesium alloy raw material is within the above range.

[0036] In some embodiments, the copper-containing material is added in the form of pure copper ingots or Al-Cu master alloys, the erbium-containing material is added in the form of Al-Er master alloys, the manganese-containing material is added in the form of Al-Mn master alloys, the zirconium-containing material is added in the form of Al-Zr master alloys, the titanium-containing material is added in the form of Al-Ti or Al-Ti-B master alloys, and the aluminum-containing material is added in the form of pure aluminum ingots.

[0037] In some embodiments, the melting temperature is 750°C to 800°C, the refining temperature is 700°C to 750°C, and the casting temperature is 700°C to 730°C.

[0038] In order to dissolve the uneven alloy precipitation phase precipitated during the cooling process into the α (Al) solid solution matrix, eliminate the element segregation occurring during the solidification process of the alloy, and prevent overburning, the present invention can adopt a single-stage or multi-stage solution treatment, and the multi-stage solution treatment can be a two-stage solution treatment or a three-stage solution treatment.

[0039] In some embodiments, a solution heat treatment is first performed at a temperature range of 450° C. to 550° C. for no more than 35 hours, and then an aging treatment is performed at a temperature range of 150° C. to 220° C. for no more than 40 hours.

[0040] In some embodiments, the solution treatment adopts a two-stage solution heat treatment process: first, a primary solution heat treatment is performed in a temperature range of 440°C to 510°C for no more than 15 hours, and then a secondary solution heat treatment is performed in a temperature range of 510°C to 550°C for no more than 20 hours.

[0041] In some embodiments, the solution treatment adopts a three-stage solution heat treatment process: keeping at 440℃~480℃ for 0.5h~10h, then heating to 480℃~510℃ for 0.5h~15h, and finally heating to 510℃~550℃ for 0.5h~10h.

[0042] The present invention adopts a multi-stage solution treatment process, which can effectively prevent the occurrence of overburning and increase the quenching temperature of the alloy, so that the precipitated phase generated in the casting process of the alloy can be dissolved into the alloy solid solution as much as possible.

[0043] In some embodiments, the aging treatment adopts a double-stage aging treatment process: first, keep it at 150° C. to 165° C. for 1 hour to 16 hours, and then keep it at 180° C. to 200° C. for 6 hours to 24 hours.

[0044] In some embodiments, the aging treatment adopts a three-stage aging treatment process: first keep at 150°C to 165°C for 1h to 10h, then keep at 170°C to 190°C for 6h to 15h, and finally increase the temperature to 190°C to 220°C for 8h to 15h.

[0045] The present invention regulates the alloy strengthening phase mainly from the following two aspects: (1) controlling the precipitation of the strengthening phase by adjusting the alloy composition; (2) controlling the precipitation of the strengthening phase by a multi-stage aging heat treatment process. Through the above regulation of the precipitation of the alloy strengthening phase, the present invention obtains a fine dispersed precipitation strengthening phase.

[0046] In some embodiments, after finishing the refinement treatment, the temperature is lowered to 700°C to 730°C for melt purification and inert gas degassing and refining, and after standing for 2min to 30min, the slag is removed and then casting is performed. In the actual production process, the alloy composition, density index (gas content) and oxide content need to be tested after the slag is removed, and casting is performed after passing the test.

[0047] As a preferred technical solution, the quality control of the melt needs to include gas content control, melt purification, control of oxide and impurity content, use of refiners, etc. Among them:

[0048] The control of gas content is mainly the control of hydrogen content. Generally, the density index of the melt is controlled to be less than 1%, preferably less than 0.5%. If the gas content in the melt is high, it is necessary to use inert gas such as nitrogen, argon, etc. for degassing.

[0049] Melt purification, oxide and impurity content control are mainly achieved by adding trace elements. For example, adding trace rare earth elements can purify aluminum alloy melts, and adding trace amounts of chlorine or boron oxide can remove slag. The rare earth element is a single rare earth element or more than one mixed rare earth element, preferably one or more of La, Ce, Pr, Nd, Y, and Sc.

[0050] The refiner used in the refinement treatment includes one or more of the commonly used titanium-boron alloy or special trace elements such as zirconium, vanadium, chromium, etc. The addition amount of these elements is generally less than 0.15wt.%.

[0051] Specifically, the relevant elements of the cast aluminum alloy of the present invention, their functions, and the preparation process are analyzed as follows:

[0052] The present invention adds Er element to the Al-Cu alloy system. First, Er element and Cu element form a high melting point Cu2Er intermetallic compound, which has very good high temperature stability, so the high temperature strength of the alloy can be significantly improved. Secondly, after the high melting point Er element is added, the solidus temperature of the alloy is increased and the solidification temperature range of the alloy is reduced, so the thermal cracking resistance of the alloy can be greatly improved. However, if Er is added in excess, the plasticity of the alloy will be significantly reduced and the manufacturing cost of the alloy will be increased. Therefore, the amount of Er added should be appropriate.

[0053] In addition, the appropriate addition of alloying elements Ti and Zr can refine the grain size of the cast alloy. The alloy also contains some inevitable alloying elements Fe and Si. In order to reduce the harm of Fe, Mn is appropriately added.

[0054] In order to obtain better high-temperature strength and plasticity comprehensive mechanical properties, it is necessary to control the morphology and distribution of Er-Cu intermetallic compounds in the alloy to obtain fine and dispersed organizational characteristics. To this end, it is necessary to convert the coarse Er-Cu intermetallic compounds formed during the casting solidification process into a fine and dispersed second phase. First, the Er-containing and Cu-containing phases are completely dissolved in the aluminum matrix by solution treatment. Secondly, the Er-Cu second phase is precipitated in the alloy as fine particles by aging treatment to obtain the best strength and plasticity matching.

[0055] In addition, the use of a multi-stage solution treatment process can effectively prevent the occurrence of overburning and increase the quenching temperature of the alloy, so that the precipitated phase produced during the casting process can be dissolved into the alloy solid solution as much as possible.

[0056] The present invention is further described below by way of examples and comparative examples.

[0057] Table 1 Alloy composition (mass percentage)

[0058] Cu Er Mn Zr Ti Fe Si other Al Example 1 5.0 1.5 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Example 2 6.0 1.5 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Example 3 7.0 1.5 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Example 4 8.0 1.5 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Example 5 9.0 1.5 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Example 6 10.0 1.5 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Example 7 6.0 0.3 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Example 8 6.0 0.8 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Example 9 6.0 2.0 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Example 10 6.0 3.0 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Embodiment 11 6.0 5.0 0.3 0.5 0.2 0.4 0.4 ≤0.2 margin Example 12 5.0 1.2 0.5 0.1 0.35 0.3 0.4 ≤0.2 margin Embodiment 13 5.0 1.2 1.5 0.3 0.30 0.5 0.2 ≤0.2 margin Embodiment 14 5.0 1.2 2.0 1.5 0.05 0.4 0.5 ≤0.2 margin Comparative Example 1 4.8 - 0.4 0.1 0.15 - - 1.0Mg, 0.2Cd margin Comparative Example 2 4.5 - 0.3 0.1 0.20 - - 0.2Mg, 0.5Ag margin

[0059] Examples 1 to 14

[0060] Examples 1 to 14 are used to illustrate the high temperature resistant and thermal cracking resistant cast aluminum alloy and the preparation method thereof disclosed in the present invention, respectively, and include the following operating steps:

[0061] 1) According to the casting aluminum alloy compositions shown in Examples 1 to 14 in Table 1 above, single substances and master alloys containing various elements are prepared respectively;

[0062] 2) Firstly, pure aluminum ingots are melted, and when the temperature reaches 750-800°C, pure copper ingots or Al-Cu master alloy, Al-Er master alloy, Al-Mn master alloy, Al-Zr master alloy are added, and the temperature is kept at 700-800°C;

[0063] 3) Add Al-Ti or Al-Ti-B master alloy at 700℃~750℃ for refinement treatment;

[0064] 4) The temperature is reduced to 700℃~730℃ for melt purification and inert gas degassing and refining. After standing for 2~30min, slag is removed, and the composition, density index (gas content) and oxide content are tested. After passing the test, pouring is performed;

[0065] 5) performing a solution heat treatment at 450°C for 12 hours and an aging treatment at 170°C for 10 hours to finally obtain a cast aluminum alloy.

[0066] Comparative Examples 1-2

[0067] Comparative Examples 1 and 2 are used to compare and illustrate the high temperature resistant and thermal cracking resistant cast aluminum alloy and the preparation method thereof disclosed in the present invention, including most of the operation steps in Example 1, and the difference is that: the single substance and alloy of each element are calculated according to the element components of the cast aluminum alloy shown in Comparative Examples 1 and 2 in Table 1, and the single substance and alloy raw materials of each element are added to the melting furnace for melting. The other operations are consistent with Example 1, and the cast aluminum alloys of Comparative Examples 1 and 2 are obtained.

[0068] Performance Testing:

[0069] The cast aluminum alloys prepared in the above-mentioned Examples 1 to 14 and Comparative Examples 1 to 2 were subjected to the following performance tests, wherein:

[0070] Room temperature mechanical properties test: Tested according to the method in GB / T 228.1-2021 "Metallic material tensile specimens Part 1: Room temperature test methods";

[0071] 300℃ mechanical properties test: Tested according to the method in GB / T 4338-2006 "High-temperature tensile test method for metallic materials";

[0072] Hot cracking tendency test: refer to the method in JB / T4022.2-1999 "Alloy casting performance test method - determination of hot cracking tendency", and select hot cracking force under the same casting conditions as the evaluation standard. The smaller the hot cracking force, the more obvious the hot cracking tendency; the larger the hot cracking force, the smaller the hot cracking tendency, indicating that the alloy has a stronger resistance to hot cracking.

[0073] The relevant test results of the cast aluminum alloy samples prepared in the above Examples 1 to 14 and Comparative Examples 1 to 2 are shown in Table 2 below.

[0074] Table 2 Mechanical properties and thermal cracking resistance of cast aluminum alloy samples

[0075]

[0076]

[0077] From the test results in Table 2 above, we can see that:

[0078] Comparative Examples 1 and 2 contain Cu elements, and the cast aluminum alloy can obtain very good high-temperature performance. The tensile strength at 300°C reaches 170MPa and 140MPa respectively, and the elongation reaches 3.5% and 12%. However, the hot cracking stress is only 8.6kN and 9.0kN, which is very easy to cause hot cracking, affecting the use of the castings.

[0079] Compared with comparative examples 1 to 2, the addition of Er element to the cast aluminum alloy effectively increases the solidus temperature of the alloy, thereby significantly increasing the hot cracking stress. The alloy's resistance to hot cracking is significantly increased. With the increase of Cu element in the alloy, the room temperature tensile strength of the alloy increases, but the elongation decreases, and with the increase of Cu element in the alloy, the hot cracking stress decreases, and the alloy's resistance to hot cracking decreases. However, the high temperature performance of the alloy increases.

[0080] As the Er content in cast aluminum alloy increases, the high temperature performance of the alloy increases, and the thermal cracking resistance also increases. However, it is necessary to keep the Er to Cu weight percentage ratio within the range of (0.05-0.84):1 to obtain the best strength and thermal cracking resistance. Too much Er will increase the liquidus temperature of the alloy and increase the content of oxidized impurities, which is not conducive to alloy casting.

[0081] The Ti and Zr elements in cast aluminum alloys are mainly used to refine the grain size of the cast alloy and obtain better room temperature mechanical properties. Fe and Si elements are inevitable alloying elements in the alloy. As long as they are controlled within the limit, good performance can be obtained. The addition of Mn elements is to eliminate the content of Fe elements in the alloy, which is generally controlled at 1 to 3 times the maximum content of Fe elements.

[0082] Embodiments 15 to 44

[0083] Examples 15 to 44 are used to further illustrate the high temperature resistant and thermal crack resistant cast aluminum alloy and its preparation method disclosed in the present invention. The alloy composition is the same as the cast aluminum alloy described in Example 3. The preparation method includes most of the operating steps in Example 3. The difference lies in the solution treatment and aging treatment to test the influence of the alloy heat treatment system on the mechanical properties of the cast aluminum alloy. Please see Table 3 below for details; other operations are consistent with Example 3, and the cast aluminum alloy is finally obtained.

[0084] Comparative Examples 3-4

[0085] Comparative Examples 3 to 4 are used to further compare and illustrate the cast aluminum alloy and the preparation method thereof disclosed in the present invention. The alloy composition is the same as that of the cast aluminum alloy described in Example 3. The preparation method includes most of the operating steps in Example 3, and the difference lies in the solution treatment and aging treatment to test the influence of the alloy heat treatment system on the mechanical properties of the cast aluminum alloy. Please see Table 3 below for details; other operations are consistent with Example 3, and the cast aluminum alloy is finally obtained.

[0086] Performance Testing:

[0087] The cast aluminum alloys prepared in the above-mentioned Examples 15 to 44 and Comparative Examples 3 to 4 were subjected to the following performance tests, wherein:

[0088] Room temperature mechanical properties test: Tested according to the method in GB / T 228.1-2021 "Metallic material tensile specimens Part 1: Room temperature test methods";

[0089] 300℃ mechanical properties test: Tested according to the method in GB / T 4338-2006 "High-temperature tensile test method for metallic materials";

[0090] The relevant test results of the cast aluminum alloy samples prepared in the above Examples 15 to 44 and Comparative Examples 3 to 4 are shown in Table 3 below.

[0091] Table 3 Effect of heat treatment system on mechanical properties of cast aluminum alloy samples

[0092]

[0093]

[0094]

[0095]

[0096]

[0097] From the test results in Table 3 above, we can see that:

[0098] In comparative example 3, the temperature during solution treatment is lower than the set solution temperature, and the solution time is less than the set solution time, resulting in the coarse Cu2Er of the alloy not being completely dissolved, and thus failing to exert the effect of second phase dispersion strengthening. Similarly, in comparative example 4, the aging temperature is lower than 150°C, and the Cu2Er phase cannot be precipitated, resulting in failure to achieve the effect of dispersion strengthening. Therefore, compared with examples 3 and 15 to 17, the mechanical properties of comparative documents 3 to 4 are poor.

[0099] It can be seen from the above examples 1 to 44 that the heat treatment system of the cast aluminum alloy affects the room temperature mechanical properties and high temperature mechanical properties of the alloy. As long as the solution temperature and time, as well as the aging temperature and time are controlled within the designed range, very good room temperature and high temperature mechanical properties can be obtained. Therefore, multi-stage heat treatment can achieve the same high strength effect while avoiding the risk of overburning.

[0100] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A high temperature resistant and thermal crack resistant cast aluminum alloy, characterized in that: Contains the following components in percentage by mass: The Cu content is 5% to 10%, the Er content is 0.3% to 5%, the Mn content is 0.3% to 2%, the Zr content is 0.1% to 1.5%, the Ti content is 0.05% to 0.35%, the Fe content is ≤0.5%, the Si content is ≤0.5%, the total amount of other elements is ≤0.2%, and the balance is Al; wherein, the mass ratio of Er to Cu elements is 0.05 to 0.84:1, and the Er element and the Cu element form a high-melting-point Cu2Er intermetallic compound with very good high-temperature stability; when the content of each element is within the above range, a high-temperature resistant and thermal cracking resistant cast aluminum alloy with excellent comprehensive performance can be obtained, wherein the tensile strength at a high temperature of 300°C is ≥210 MPa, the elongation is ≥7%, and the alloy has good thermal cracking resistance.

2. The high temperature resistant and thermal crack resistant cast aluminum alloy according to claim 1, characterized in that: Contains the following components in percentage by mass: The Cu content is 6% to 8%, the Er content is 0.8% to 3%, the Mn content is 0.3% to 1.5%, the Zr content is 0.1% to 1.5%, the Ti content is 0.05% to 0.35%, the Fe content is ≤0.5%, the Si content is ≤0.5%, the total amount of other elements is ≤0.2%, and the balance is Al.

3. A method for preparing a high temperature resistant and thermal cracking resistant cast aluminum alloy as claimed in claim 1 or 2, characterized in that: The steps include: Weighing the required proportions of copper-containing material, erbium-containing material, manganese-containing material, zirconium-containing material, titanium-containing material, and aluminum-containing material according to the element ratio in the casting aluminum alloy, smelting the copper-containing material, erbium-containing material, manganese-containing material, zirconium-containing material, and aluminum-containing material, adding the titanium-containing material after smelting for refinement treatment, and then casting and forming, and then performing one or more stages of solid solution treatment and aging treatment to obtain the casting aluminum alloy; After the refinement treatment is completed, the temperature is lowered to 700°C to 730°C for melt purification and inert gas degassing and refining, and after standing for 2min to 30min, the slag is removed and casting is performed; First, a solution heat treatment is carried out at a temperature range of 450°C to 550°C for no more than 35 hours, and then an aging treatment is carried out at a temperature range of 150°C to 220°C for no more than 40 hours.

4. The method for preparing the high temperature resistant and thermal cracking resistant cast aluminum alloy according to claim 3, characterized in that: The solution treatment adopts a two-stage solution heat treatment process: first, a primary solution heat treatment is performed in a temperature range of 440°C to 510°C for no more than 15 hours, and then a secondary solution heat treatment is performed in a temperature range of 510°C to 550°C for no more than 20 hours.

5. The method for preparing the high temperature resistant and thermal cracking resistant cast aluminum alloy according to claim 3, characterized in that: The solution treatment adopts a three-stage solution heat treatment process: keeping the temperature at 440°C to 480°C for 0.5h to 10h, then heating to 480°C to 510°C for 0.5h to 15h, and finally heating to 510°C to 550°C for 0.5h to 10h.

6. The method for preparing the high temperature resistant and thermal cracking resistant cast aluminum alloy according to claim 3, characterized in that: The aging treatment adopts a double-stage aging treatment process: first, keeping the temperature at 150°C to 165°C for 1 h to 16 h, and then keeping the temperature at 180°C to 200°C for 6 h to 24 h.

7. The method for preparing the high temperature resistant and thermal cracking resistant cast aluminum alloy as claimed in claim 3, characterized in that: The aging treatment adopts a three-stage aging treatment process: first, keep the temperature at 150°C to 165°C for 1h to 10h, then keep the temperature at 170°C to 190°C for 6h to 15h, and finally increase the temperature to 190°C to 220°C for 8h to 15h.

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