A high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy and preparation method thereof

Abstract

The present invention belongs to the field of aluminum alloy materials, and specifically relates to a high-strength, high-toughness, high-fatigue-resistance cast aluminum alloy and a preparation method thereof. The aluminum alloy matrix includes two or more nano-sized phases, and its elemental composition includes Al and any other one or more elements among Al, Si, Cu, and Mg elements, and one or more of Sn, Ag, Zn, In, and Hf; the alloy also includes two or more submicron-sized phases, and its elemental composition includes Al and any other one or more among Al, Fe, Mn, Cr, V, Zr, Ti, and Mo elements, and any one or more of Cu, Ni, Y, Er, and Nb elements. The preparation method includes non-isothermal + isothermal solution and aging treatment of the aluminum alloy ingot. The cast aluminum alloy and the preparation method of the present invention realize the number density and size control of the nano-sized phase and the submicron-sized strengthening phase, and improve the toughness and fatigue resistance of the alloy.

Description

Technical Field

[0001] The invention belongs to the field of aluminum alloy materials, and specifically relates to a high-strength, high-toughness and high-fatigue-resistance casting aluminum alloy and a preparation method thereof. Background Art

[0002] Cast aluminum alloys are widely used in transportation, aerospace and automobile fields due to their medium strength, good fluidity, low cost and high production efficiency. In the field of lightweight automobiles, cast aluminum alloys are often used in the preparation of automobile bodies, wheels, fuel tanks, aluminum cans, machine covers, motor housings, steering knuckles, push-pull rods and other parts. In order to ensure the safety of parts, cast aluminum alloys are required to have high strength and high fatigue resistance.

[0003] Chinese invention patent CN109266923A discloses a high-strength, high fatigue resistance Al-Cu-Mg-Si-Mn aluminum alloy and its processing method, which achieves effective control of the number density of dispersed phases, the area percentage of coarse phases and the recrystallization area fraction in the alloy through composition design and heat treatment process adjustment, thereby obtaining an aluminum alloy with high strength and high fatigue life.

[0004] Chinese invention patent CN109295355A discloses a fatigue-resistant and corrosion-resistant Al-Mg-Si-Cr aluminum alloy for rail transit and a preparation method thereof, which obtains an aluminum alloy with high fatigue resistance through composition design, heat treatment, and rolling process adjustment.

[0005] However, the aluminum alloy and processing method thereof disclosed in the above-mentioned patents, as well as some other prior arts, are all about improving the fatigue resistance of deformed aluminum alloys such as Al-Cu and Al-Mg-Si series, which require means such as recrystallization caused by plastic deformation processing to achieve fatigue resistance. For cast aluminum alloys that have not undergone plastic deformation processing, how to simultaneously improve their toughness and fatigue resistance is of great significance to the quality improvement of cast aluminum alloy materials for automobiles. Summary of the invention

[0006] The object of the present invention is to provide a high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy and a preparation method thereof, so as to solve one or more technical problems existing in the prior art.

[0007] In order to achieve the above-mentioned invention object, this application provides the following technical solutions:

[0008] The present invention provides a high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy, comprising a matrix, at least two nano-sized phases and at least two submicron-sized phases;

[0009] The size range of the nano-sized phase is 1-50 nm;

[0010] The phase element composition of the nano-sized phase includes Al, element A1 and element A2; the element A1 is selected from one or more of Si, Cu and Mg, and the element A2 is selected from one or more of Sn, Ag, Zn, In and Hf;

[0011] The phase element composition of the submicron-sized phase includes Al, element B1 and element B2; the element B1 is selected from one or more of Fe, Mn, Cr, V, Zr, Ti and Mo, and the element B2 is selected from one or more of Cu, Ni, Y, Er and Nb.

[0012] Preferably, the two-dimensional morphology of the nano-sized phase is selected from one or more of a strip, a polygon and a sphere.

[0013] Preferably, in the high-strength, toughness and high-fatigue-resistance cast aluminum alloy, the nano-sized phase and the matrix are in a completely coherent relationship, and the crystal structure is selected from one or more of a monoclinic structure, a tetragonal structure, a hexagonal structure and a cubic structure.

[0014] Preferably, the size range of the submicron phase is 50-500 nm; wherein the number ratio of the submicron phase in the size range of 100-300 nm is 70-80%, and the number ratio of the submicron phase in the remaining size range is 20-30%.

[0015] Preferably, the submicron-sized phase in the cast aluminum alloy is in a coherent or semi-coherent relationship with the matrix, and its crystal structure is selected from one or more of a simple cubic structure, a complex cubic structure, a tetragonal structure, a monoclinic structure and a close-packed hexagonal structure.

[0016] Preferably, the two-dimensional morphology of the submicron-sized phase is selected from one or more of polygonal, short rod-shaped and spherical.

[0017] Preferably, the number density of the submicron size phase is 10 13 -10 20 / m 3 .

[0018] Preferably, the composition of the high-strength, toughness and high fatigue resistance cast aluminum alloy is as follows, by weight fraction: Si 3~9%, Mg 0.1~0.7%, Fe 0.01~0.3%, Mn 0.01~0.5%, Cr 0.01~0.2%, Zr 0.01~0.3%, Mo 0.01~0.2%, Ti 0.01~0.1%, Cu 1%~4%, Ni 0.01~0.1%, Y 0.01~0.1%, V 0.01~0.1%, Sn 0.01~0.2%, Ag 0.01~0.5%, Zn 0.1~3%, In 0.01~0.1%, Hf 0.01~0.3%, Er 0.01~0.1%, Nb 0.01~0.1%, and the rest is Al.

[0019] The present invention also provides a method for preparing the above-mentioned high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy, comprising the following steps:

[0020] S1: After batching, smelting and casting are performed to obtain an aluminum alloy ingot; the ingredients of the batching are as follows by weight: Si3~9%, Mg 0.1~0.7%, Fe 0.01~0.3%, Mn 0.01~0.5%, Cr 0.01~0.2%, Zr 0.01~0.3%, Mo 0.01~0.2%, Ti 0.01~0.1%, Cu 1%~4%, Ni 0.01~0.1%, Y 0.01~0.1%, V 0.01~0.1%, Sn 0.01~0.2%, Ag 0.01~0.5%, Zn 0.1~3%, In 0.01~0.1%, Hf 0.01~0.3%, Er 0.01~0.1%, Nb 0.01~0.1%, and the rest is Al;

[0021] S2: performing non-isothermal-isothermal solution treatment on the aluminum alloy ingot; the method of the non-isothermal-isothermal solution treatment is: heating the aluminum alloy ingot from room temperature (25±5°C) to 450-500°C at a heating rate of 10-30°C per hour, keeping the temperature for 1-16 hours, and then keeping the temperature at 500-530°C for 1-6 hours, and water quenching or air cooling;

[0022] S3: performing aging treatment on the aluminum alloy ingot after the non-isothermal-isothermal solution treatment in the step S2 to obtain the high-strength, toughness and high fatigue resistance cast aluminum alloy; the aging treatment method is: heating the aluminum alloy ingot after the non-isothermal-isothermal solution treatment in the step S2 at 70-90°C for 1-8 h, heating it to 100-120°C for 1-6 h, and then heating it to 160-200°C for 1-6 h to complete the aging treatment.

[0023] Preferably, in step S1, the casting method is selected from any one of gravity differential pressure casting, high pressure differential pressure casting, extrusion differential pressure casting, low pressure differential pressure casting and differential pressure casting.

[0024] The alloy obtained by the present invention has a yield strength of greater than or equal to 320 MPa, an elongation of greater than or equal to 8%, a tensile strength of greater than or equal to 400 MPa, and a high cycle fatigue strength of greater than or equal to 130 MPa (stress ratio is -1, and the number of cycles is greater than 10). 7 ).

[0025] The technical solution of the present invention has the following advantages over the prior art:

[0026] The cast aluminum alloy and preparation method of the present invention regulate the number density and size of nano-sized phases and submicron phases by controlling the alloy composition and ratio, as well as the temperature and time of heat treatment during the preparation process, so that one or more nano-sized phases and submicron phases with a certain density, number, size and crystal structure are formed in the crystal of the aluminum alloy, so that the aluminum alloy has both high strength and toughness and high fatigue performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the alloy structure of Example 1 of the present invention;

[0028] Figure 2 is a schematic diagram of the alloy structure of Example 2 of the present invention;

[0029] Figure 3 Schematic diagram of the alloy structure of Example 3 of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0031] The following are references to the test standards for the mechanical properties (yield strength, elongation, tensile strength, etc.) of the metal materials described in the following embodiments:

[0032] GB / T 228.1-2021 Tensile test of metallic materials Part 1: Room temperature test method;

[0033] Fatigue performance test standard reference:

[0034] "GB / T3075-2020 Axial force control method for fatigue test of metal materials".

[0035] The elemental composition of the nano- and submicron-sized phases described in the following embodiments is determined using transmission electron microscopy (TEM) X-ray energy spectroscopy (EDS), electron energy loss spectroscopy (EELS) or scanning transmission electron microscopy high angle annular dark field imaging (HAADF-STEM, High Angle Angular Dark Field-Scanning Transmission Electron Microscopy) to determine the phase composition. Example 1

[0036] The present embodiment discloses a high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy and a preparation method thereof, wherein the components of the aluminum alloy and the weight percentages of the components are: Si 4%, Mg 0.22%, Fe 0.21%, Mn 0.01%, Cr 0.18%, Zr 0.24%, Mo 0.07%, Ti 0.10%, Cu 1%, Ni 0.01%, Y 0.01%, V 0.07%, Sn 0.01%, Ag 0.01%, Zn 0.1%, In 0.01%, Hf 0.15%, Er 0.01%, Nb 0.01%, and the rest is Al.

[0037] The method for preparing a high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy based on the above composition in this embodiment comprises the following steps:

[0038] (1) preparing and melting the aluminum alloy with the above-mentioned components, and obtaining an ingot by gravity casting;

[0039] (2) performing a non-isothermal + isothermal solution treatment on the aluminum alloy ingot, comprising:

[0040] The aluminum alloy ingot is placed in a heat treatment furnace, the ingot is heated from room temperature to 500°C at a rate of 10°C per hour, then kept at 500°C for 1 hour, and then kept at 520°C for 3 hours, and then water quenched;

[0041] The alloy ingot after solution treatment was kept at 70°C for 8 hours, then heated to 100°C for 6 hours, and then continued to be heated to 190°C for 2 hours for aging treatment to obtain the final high-strength, toughness and high fatigue resistance cast aluminum alloy.

[0042] The alloy structure obtained in this embodiment is as follows Figure 1As shown, through organizational observation, it is found that there are a large number of nano-sized phases and submicron-sized phases in the alloy matrix of this embodiment, wherein the size range of the nano-sized phase is 1-50 nm, the phase element composition includes Al, Si, Cu, Mg, Sn, Ag, Zn, In and Hf elements, the two-dimensional morphology includes long strips, polygons and spheres, and the crystal structure includes monoclinic structure, tetragonal structure, hexagonal structure and cubic structure; the element composition of the submicron-sized phase includes Al, Fe, Mn, Cr, V, Zr, Ti, Mo and Cu, Ni, Y, Er and Nb elements; the submicron-sized phase size range is 50-500 nm, wherein the number ratio of the submicron phase in the size range of 100-300 nm is 70%, and the number ratio of the submicron phase in the remaining size range is 30%; the submicron-sized phase is in a coherent or semi-coherent relationship with the matrix, and its crystal structure includes simple cubic structure, complex cubic structure, tetragonal structure, monoclinic structure and close-packed hexagonal structure. The two-dimensional morphology of the submicron-sized phase includes polygons, short rods and spheres. The statistical result shows that the number density of submicron size phase in the alloy is 10 14 / m 3 ;

[0043] The alloy was tested to have a yield strength of 345 MPa, an elongation of 10.9%, a tensile strength of 418 MPa, and a high-cycle fatigue strength of 131 MPa (stress ratio of -1, cycles greater than 10). 7 ). Example 2

[0044] The present embodiment discloses a high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy and a preparation method thereof, wherein the components and weight percentages are: Si 7%, Mg 0.1%, Fe 0.15%, Mn 0.25%, Cr 0.2%, Zr 0.3%, Mo 0.01%, Ti 0.05%, Cu 1.7%, Ni 0.1%, Y 0.023%, V 0.1%, Sn 0.07%, Ag 0.37%, Zn 1.65%, In 0.051%, Hf0.01%, Er 0.053%, Nb 0.049%, and the rest is Al.

[0045] The method for preparing a high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy based on the above composition in this embodiment comprises the following steps:

[0046] (1) preparing and smelting the aluminum alloy, and obtaining an ingot by extrusion casting;

[0047] (2) performing a non-isothermal + isothermal solution treatment on the aluminum alloy ingot, comprising:

[0048] The aluminum alloy ingot is placed in a heat treatment furnace, and the ingot is heated from room temperature 25°C to 450°C at a rate of 14°C per hour, and then kept at 450°C for 8 hours, and then kept at 525°C for 6 hours, and then air-cooled;

[0049] The alloy ingot after solution treatment was kept at 90°C for 1 h, then heated to 105°C for 4.5 h, and then continued to be heated to 160°C for 6 h for aging treatment to obtain the final high-strength, high-toughness and high-fatigue resistance cast aluminum alloy.

[0050] The alloy structure obtained in this embodiment is as follows Figure 2 As shown, through organizational observation, it is found that there are a large number of nano-sized phases and submicron-sized phases in the alloy matrix of this embodiment, wherein the size range of the nano-sized phase is 1-50 nm, the phase element composition includes Al, Si, Cu, Mg, Sn, Ag, Zn, In and Hf elements, the two-dimensional morphology includes long strips, polygons and spheres, and the crystal structure includes monoclinic structure, tetragonal structure, hexagonal structure and cubic structure; the element composition of the submicron-sized phase includes Al, Fe, Mn, Cr, V, Zr, Ti, Mo and Cu, Ni, Y, Er and Nb elements; the submicron-sized phase size range is 50-500 nm, wherein the number of submicron phases in the size range of 100-300nm accounts for 75%, and the number of submicron phases in the remaining size ranges accounts for 25%; the submicron-sized phase is in a coherent or semi-coherent relationship with the matrix, and its crystal structure includes simple cubic structure, complex cubic structure, tetragonal structure, monoclinic structure and close-packed hexagonal structure. The two-dimensional morphology of the submicron-sized phase includes polygons, short rods and spheres. The statistical result shows that the number density of submicron size phase in the alloy is 10 16 / m 3 ;

[0051] The alloy was tested to have a yield strength of 350 MPa, an elongation of 10%, a tensile strength of 421 MPa, and a high-cycle fatigue strength of 135 MPa (stress ratio of -1, cycles greater than 10). 7 ). Example 3

[0052] The present embodiment discloses a high-strength, high-toughness and high-fatigue resistance cast aluminum alloy and a preparation method thereof, wherein the components and weight percentages are: Si 9%, Mg 0.33%, Fe 0.25%, Mn 0.12%, Cr 0.15%, Zr 0.21%, Mo 0.16%, Ti0.06%, Cu 2.6%, Ni 0.02%, Y 0.71%, V 0.01%, Sn 0.16%, Ag 0.13%, Zn 0.91%, In 0.03%, Hf0.05%, Er 0.025%, Nb 0.31%, and the rest is Al.

[0053] The method for preparing a high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy based on the above composition in this embodiment comprises the following steps:

[0054] (1) preparing and smelting the aluminum alloy, and obtaining an ingot by high pressure casting;

[0055] (2) performing a non-isothermal + isothermal solution treatment on the aluminum alloy ingot, comprising:

[0056] The aluminum alloy ingot is placed in a heat treatment furnace, the ingot is heated from room temperature to 460°C at a rate of 20°C per hour, then kept at 460°C for 4 hours, and then kept at 510°C for 4 hours, and then water quenched;

[0057] The alloy ingot after solution treatment was kept at 76°C for 6 h, then heated to 120°C for 1 h, and then continued to be heated to 175°C for 5 h for aging treatment to obtain the final high-strength, toughness and high fatigue resistance cast aluminum alloy.

[0058] The alloy structure obtained in this embodiment is as follows Figure 3 As shown, through organizational observation, it is found that there are a large number of nano-sized phases and submicron-sized phases in the alloy matrix of this embodiment, wherein the size range of the nano-sized phase is 1-50 nm, the phase element composition includes Al, Si, Cu, Mg, Sn, Ag, Zn, In and Hf elements, the two-dimensional morphology includes long strips, polygons and spheres, and the crystal structure includes monoclinic structure, tetragonal structure, hexagonal structure and cubic structure; the element composition of the submicron-sized phase includes Al, Fe, Mn, Cr, V, Zr, Ti, Mo and Cu, Ni, Y, Er and Nb elements; the size range of the submicron phase is 50-500 nm, wherein the number ratio of the submicron phase in the size range of 100-300 nm is 80%, and the number ratio of the submicron phase in the remaining size range is 20%; the submicron-sized phase is in a coherent or semi-coherent relationship with the matrix, and its crystal structure includes simple cubic structure, complex cubic structure, tetragonal structure, monoclinic structure and close-packed hexagonal structure. The two-dimensional morphology of the submicron-sized phase includes polygons, short rods and spheres. The statistical result shows that the number density of submicron size phase in the alloy is 10 18 / m 3 ;

[0059] The alloy was tested to have a yield strength of 320 MPa, an elongation of 12%, a tensile strength of 400 MPa, and a high-cycle fatigue strength of 134 MPa (stress ratio of -1, cycles greater than 10). 7 ).

[0060] Comparative Example 1

[0061] Compared with the conventional Al-Si-Cu-Mg casting alloy, its components and weight percentages are: Si 7%, Mg 0.5%, Fe0.1%, Cu 3.0%, and the rest is Al.

[0062] The conventional casting aluminum alloy preparation method of the above composition comprises the following steps:

[0063] (1) preparing and smelting the aluminum alloy, and obtaining an ingot by differential pressure casting;

[0064] (2) performing isothermal solution treatment and aging treatment on the aluminum alloy ingot, comprising:

[0065] Placing the aluminum alloy ingot in a heat treatment furnace, keeping the ingot at 490° C. for 12 hours, and then performing water quenching treatment;

[0066] The alloy ingot after solution treatment was kept at 1800°C for 11 h for aging treatment to obtain a cast aluminum alloy in an artificially aged state.

[0067] The alloy was tested to have a yield strength of 340 MPa, an elongation of 5.6%, a tensile strength of 380 MPa, and a high-cycle fatigue strength of 105 MPa (stress ratio of -1, cycles greater than 10). 7 ).

[0068] Effect evaluation 1

[0069] It can be seen from the performance results of Example 1, Example 2 and Example 3 compared with the comparative example that the alloy and process design of this patent can significantly improve the strength and fatigue resistance of the cast aluminum alloy material, and has obvious innovative effects.

[0070] The technical contents and technical features of the present invention have been disclosed as above. However, those skilled in the art may still make various substitutions and modifications based on the teachings and disclosures of the present invention without departing from the spirit of the present invention. Therefore, the protection scope of the present invention should not be limited to the contents disclosed in the embodiments, but should include various substitutions and modifications that do not depart from the present invention and are covered by the claims of this patent application.

Claims

1. A high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy, characterized in that: comprising a matrix, at least two nanometer-sized phases, and at least two submicrometer-sized phases; The size range of the nano-sized phase is 1-50 nm; The phase element composition of the nano-sized phase includes Al, element A1 and element A2; the element A1 is selected from one or more of Si, Cu and Mg, and the element A2 is selected from one or more of Sn, Ag, Zn, In and Hf; The phase element composition of the submicron size phase includes Al, element B1 and element B2; the element B1 is selected from one or more of Fe, Mn, Cr, V, Zr, Ti and Mo, and the element B2 is selected from one or more of Cu, Ni, Y, Er and Nb; In the high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy, the nano-sized phase is in a completely coherent relationship with the matrix, and the crystal structure is selected from one or more of a monoclinic structure, a tetragonal structure, a hexagonal structure and a cubic structure; the size range of the submicron-sized phase is 50-500 nm; Among them, the number proportion of submicron-sized phases in the size range of 100-300 nm is 70-80%; The composition of the high-strength, toughness and high fatigue resistance cast aluminum alloy is as follows, by weight fraction: Si 3-9%, Mg 0.1-0.7%, Fe 0.01-0.3%, Mn 0.01-0.5%, Cr 0.01-0.2%, Zr 0.01-0.3%, Mo 0.01-0.2%, Ti 0.01-0.1%, Cu 1%-4%, Ni 0.01-0.1%, Y 0.01-0.1%, V 0.01-0.1%, Sn 0.01-0.2%, Ag 0.01-0.5%, Zn 0.1-3%, In 0.01-0.1%, Hf 0.01-0.3%, Er 0.01-0.1%, Nb 0.01-0.1%, and the rest is Al.

2. The high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy according to claim 1, characterized in that: The two-dimensional morphology of the nano-sized phase is selected from one or more of a strip, a polygon and a sphere.

3. The high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy according to claim 1, characterized in that: The submicron-sized phase in the cast aluminum alloy is in a coherent or semi-coherent relationship with the matrix, and its crystal structure is selected from one or more of a simple cubic structure, a complex cubic structure, a tetragonal structure, a monoclinic structure and a close-packed hexagonal structure.

4. The high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy according to claim 1, characterized in that: The two-dimensional morphology of the submicron-sized phase is selected from one or more of polygonal, short rod-shaped and spherical.

5. The high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy according to claim 1, characterized in that: The number density of the submicron-sized phase is 10 13 -10 20 / m 3 .

6. A method for preparing the high-strength, high-toughness and high-fatigue-resistance cast aluminum alloy according to any one of claims 1 to 5, characterized in that: The steps include: S1: After batching, smelting and casting are performed to obtain an aluminum alloy ingot; the ingredients of the batching are as follows by weight: Si 3-9%, Mg 0.1-0.7%, Fe 0.01-0.3%, Mn 0.01-0.5%, Cr 0.01-0.2%, Zr 0.01-0.3%, Mo 0.01-0.2%, Ti 0.01-0.1%, Cu 1%-4%, Ni 0.01-0.1%, Y 0.01-0.1%, V 0.01-0.1%, Sn 0.01-0.2%, Ag 0.01-0.5%, Zn 0.1-3%, In 0.01-0.1%, Hf 0.01-0.3%, Er 0.01-0.1%, Nb 0.01-0.1%, and the rest is Al; S2: performing non-isothermal-isothermal solution treatment on the aluminum alloy ingot; the method of the non-isothermal-isothermal solution treatment is: heating the aluminum alloy ingot from room temperature to 450-500°C at a heating rate of 10-30°C per hour, keeping the temperature for 1-16 hours, and then keeping the temperature at 500-530°C for 1-6 hours, and water quenching or air cooling; S3: performing aging treatment on the aluminum alloy ingot after the non-isothermal-isothermal solution treatment in the step S2 to obtain the high-strength, toughness and high fatigue resistance cast aluminum alloy; the aging treatment method is: heating the aluminum alloy ingot after the non-isothermal-isothermal solution treatment in the step S2 at 70-90°C for 1-8 h, heating it to 100-120°C for 1-6 h, and then heating it to 160-200°C for 1-6 h to complete the aging treatment.

7. The preparation method according to claim 6, characterized in that: In the step S1, the casting method is selected from any one of gravity differential pressure casting, high pressure differential pressure casting, extrusion differential pressure casting, low pressure differential pressure casting and differential pressure casting.

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