Low-carbon environment-friendly high-toughness aluminum alloy and preparation method thereof

Abstract

The invention discloses a low-carbon environment-friendly high-toughness aluminum alloy and a preparation method thereof. According to the method, special alloy elements are added for reaction, standing and filtration for iron removal, ceramic filtration for slag removal and electromagnetic iron removal, low carbon and environmental protection in the preparation and production process of the high-strength and high-toughness aluminum alloy are achieved, meanwhile, reasonable Cd is designed, nucleation of second-phase elements is promoted, nanoscale particles are separated out, the dispersion strengthening effect is achieved, and the high-strength and high-toughness aluminum alloy is obtained. And finally, the low-carbon environment-friendly high-toughness aluminum alloy material is prepared, resource recycling can be achieved, and therefore carbon emission is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a low-carbon, environmentally friendly, high-strength and toughness aluminum alloy and a preparation method thereof. Background Art

[0002] Aluminum alloy has many advantages such as low density, high strength, good heat conduction performance, and small thermal expansion coefficient. It can reduce weight, reduce wear, reduce lubricant consumption, and reduce piston clearance, meeting the conditions for replacing traditional steel materials.

[0003] Deficiencies of existing technology:

[0004] Currently, the high-strength and high-toughness aluminum alloy materials used in automotive structural parts are mostly A356.2. In the industrial preparation of this material, the control of impurity elements such as Fe, Zn, Cu, and Mn is extremely strict, making it difficult to choose recycled aluminum as the raw material for production and preparation. Electrolytic aluminum is refined into pure aluminum by electrolyzing aluminum ore, and the energy consumption and production costs brought about by the preparation process are relatively high. Summary of the invention

[0005] The object of the present invention is to provide a low-carbon, environmentally friendly, high-strength and toughness aluminum alloy and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a low-carbon, environmentally friendly, high-strength and toughness aluminum alloy, the material composition of the aluminum alloy includes 0-0.2wt% Cu, 6.5-8.5wt% Si, 0-0.15wt% Zn, 0.06-0.25wt% Mn, 0.25-0.45wt% Mg, 0-0.25wt% Fe, 0.010-0.025wt% Sr, 0.05-0.2wt% Cr, 0.03-0.15wt% Ti, 0.0040-0.025wt% B, 0.003-0.025wt% Cd, and the balance is Al and 0-0.1wt% impurities.

[0007] Preferably, the mass relationship between Fe, Mn and Cr is:

[0008] 2.5<(Fe+Mn+Cr):10*B<10.5;

[0009] The aluminum alloy has a tensile strength greater than 320 MPa, a yield strength greater than 240 MPa, and an elongation after fracture greater than 6.0%.

[0010] The present invention also provides a method for preparing a low-carbon, environmentally friendly, high-strength and tough aluminum alloy, which specifically comprises the following steps:

[0011] S1. Prepare raw materials according to the aluminum alloy material formula, weigh the corresponding percentages of each raw material for preparation, and after the smelting furnace is dried and preheated, put the prepared raw materials into the furnace in order, and obtain aluminum liquid after hot melting and stirring;

[0012] S2, refining the aluminum melt;

[0013] S3, feeding the aluminum solution into a casting forming device for forming;

[0014] S4. heat-treating the cast sample.

[0015] Preferably, in step S1, the drying preheating temperature is set to 100-450° C., the hot melting temperature is set to 730-800° C., and the stirring time is set to 5-15 minutes.

[0016] Preferably, the step S2 specifically includes the following steps:

[0017] a1. Carry out preliminary degassing and impurity removal;

[0018] a2. Add aluminum rare earth boron master alloy, AlMn, AlCr master alloy, and rotate and stir to form B x (FeMnCr) y High density precipitation phase, and let stand for 25 to 35 minutes;

[0019] a3. Will not contain B x (FeMnCr) y The solution in the furnace of the high-density precipitation phase is discharged into the clean degassing box for GBF rotary online degassing;

[0020] a4. Insert the electrodes into both ends of the degassing box to perform electromagnetic iron removal to remove smaller iron-containing impurities.

[0021] a5. The aluminum solution after rotary degassing flows through the filter box, and the alloy melt is purified again through the preheated ceramic filter plate, and the pore size of the ceramic filter plate is 50ppi.

[0022] Preferably, the molding equipment in step S3 is selected as a gravity casting machine, a low-pressure casting machine or an extrusion casting equipment.

[0023] Preferably, the step S4 specifically includes the following steps:

[0024] b1. Heat in a heat treatment box to 525-535°C and keep warm for 4 hours;

[0025] b2. Perform water quenching, set the water temperature to 50-70°C, and the water quenching time to 20-40s;

[0026] b3. Drying is carried out, and after drying, the aluminum is put into aging aluminum for aging treatment. The aging temperature is set to 170°C, the aging time is 4.5 hours, and the cooling method after aging is furnace cooling, and the cooling rate is 5°C / min.

[0027] Preferably, in the step a1, a protective gas is introduced into the alloy melt, the protective gas is selected from nitrogen or argon, the amount of protective gas introduced is set to 0.15-6 L / min, RJ-01 refining agent is added, the refining time is 20-30 min, and the amount of solid refining agent added is 0.2%-0.5% of the melt mass.

[0028] Preferably, in the step a1, the aluminum alloy melt after standing and removing impurities is placed into a degassing box along the flow channel, and the degassing box is equipped with a double-rotor rotary degasser to perform full-line degassing. The rotor is a graphite turntable, and the rotor speed is set to 400-550r / min. The inert protective gas introduced is argon, the argon pressure is 0.3-0.5MPa, and the flow rate is 18-28L / min.

[0029] Preferably, in step a5, the aluminum liquid degassing box is set to have a depth of 800 mm, a width of 400 mm, a length of 500 mm, a temperature of 680-700° C., an operating frequency of 20-50 Hz, a current of 20 A, a voltage of 220 V, an electrode length of 950 mm, and a depth of 600-700 mm into the aluminum liquid.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The low-carbon, environmentally friendly, high-strength and toughness aluminum alloy and its preparation method realize low carbon and environmental protection in the production process of high-strength and toughness aluminum alloy preparation by adding special alloy elements for reaction static filtration and iron removal, ceramic filtration and slag removal, and electromagnetic iron removal. At the same time, reasonable Cd is designed to promote the nucleation of second phase elements, precipitate nano-scale particles, and play a role in dispersion strengthening. Finally, a low-carbon, environmentally friendly, high-strength and toughness aluminum alloy material is prepared, which can realize resource recycling and thus reduce carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the aluminum solution purification flow chart of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0034] In the description of the present invention, it is necessary to understand that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0035] In the description of this patent, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "setting" should be understood in a broad sense, for example, it can be fixed connection, setting, or detachable connection, setting, or integrated connection, setting. For ordinary technicians in this field, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "several" is two or more, unless otherwise clearly and specifically defined.

[0037] Example 1

[0038] The present invention provides a low-carbon, environmentally friendly, high-strength and toughness aluminum alloy technical solution: the material composition of the aluminum alloy includes 0.1wt% Cu, 7.2wt% Si, 0.08wt% Zn, 0.1wt% Mn, 0.38wt% Mg, 0.15wt% Fe, 0.015wt% Sr, 0.065wt% Cr, 0.042wt% Ti, 0.0075wt% B, 0.004wt% Cd, and the balance is Al and 0.05wt% impurities.

[0039] This preparation method specifically comprises the following steps:

[0040] S1. Prepare raw materials according to the aluminum alloy material formula, weigh the corresponding percentage of each raw material for preparation, and after the smelting furnace is dried and preheated, put the prepared raw materials into the furnace in order, and obtain aluminum liquid after hot melting and stirring. Set the drying and preheating temperature to 350°C and the hot melting temperature to 750°C. The order of adding raw materials is: recycled aluminum alloy ingot, Cu element, Mg element, Zn element, Si element, Mn element. After complete melting, add aluminum rare earth boron alloy and AlCd master alloy, and stir for 5 to 15 minutes;

[0041] S2, refining the aluminum melt;

[0042] a1. Carry out preliminary degassing and impurity removal, introduce protective gas into the alloy melt, the protective gas is selected as nitrogen or argon, the protective gas introduction amount is set to 36L / min, add RJ-01 refining agent, the refining time is 30min, and the addition amount of solid refining agent is 0.38% of the melt mass; put the aluminum alloy melt after static impurity removal into the degassing box along the flow channel, and install a double-rotor rotary degasser in the degassing box for full online degassing. The rotor is a graphite turntable, and the rotor speed is set to 500r / min. The inert protective gas introduced is argon, the argon pressure is 0.4MPa, and the flow rate is 25L / min

[0043] a2. Add aluminum rare earth boron master alloy, AlMn, AlCr master alloy, and rotate and stir to form B x (FeMnCr) y High density precipitation phase, and let stand for 30 minutes;

[0044] a3. Will not contain B x (FeMnCr) y The solution in the furnace of the high-density precipitation phase is discharged into the clean furnace body for GBF rotary online degassing;

[0045] a4. Insert the electrodes into both ends of the degassing box to perform electromagnetic iron removal to remove smaller iron-containing impurities.

[0046] a5. The aluminum solution after rotary degassing flows through the filter box, and the alloy melt is purified again through the preheated ceramic filter plate, the pore size of the ceramic filter plate is 50ppi; the aluminum liquid degassing box is set to have a depth of 800mm, a width of 400mm, a length of 500mm, a temperature of 680-700℃, an operating frequency of 20-50Hz, a current of 20A, a voltage of 220V, an electrode length of 950mm, and a depth of 600-700mm into the aluminum liquid;

[0047] S3, feeding the aluminum solution into a casting forming device for forming, wherein the forming device is selected from a gravity casting machine, a low pressure casting machine or an extrusion casting device;

[0048] S4, heat treating the cast sample;

[0049] b1. Heat in a heat treatment box to 525-535°C and keep warm for 4 hours;

[0050] b2. Perform water quenching, set the water temperature to 50-70°C, and the water quenching time to 10s;

[0051] b3. Drying is carried out, and after drying, the aluminum is put into aging aluminum for aging treatment. The aging temperature is set to 170°C, the aging time is 4.5 hours, and the cooling method after aging is furnace cooling, and the cooling rate is 5°C / min.

[0052] After treatment, the mass fraction ratio of (Fe+Mn+Cr):10*B is 4.2, the total amount of remaining impurities is 0.05wt%, the tensile strength is 338MPa, the yield strength is 253MPa, and the elongation after fracture is 6.5%.

[0053] Example 2

[0054] The present invention provides a low-carbon, environmentally friendly, high-strength and toughness aluminum alloy technical solution: the material composition of the aluminum alloy includes 0.08wt% Cu, 6.8wt% Si, 0.05wt% Zn, 0.18wt% Mn, 0.4wt% Mg, 0.2wt% Fe, 0.018wt% Sr, 0.1wt% Cr, 0.13wt% Ti, 0.0025wt% Ca; 0.015wt% B, 0.005wt% Cd, and the balance is Al and 0.06wt% impurities.

[0055] This preparation method specifically comprises the following steps:

[0056] S1. Prepare raw materials according to the aluminum alloy material formula, weigh the corresponding percentage of each raw material for preparation, and after the smelting furnace is dried and preheated, put the prepared raw materials into the furnace in order, and obtain aluminum liquid after hot melting and stirring. Set the drying and preheating temperature to 350°C and the hot melting temperature to 750°C. The order of adding raw materials is: recycled aluminum alloy ingot, Cu element, Mg element, Zn element, Si element, Mn element. After complete melting, add aluminum rare earth boron alloy and AlCd master alloy, and stir for 5 to 15 minutes;

[0057] S2, refining the aluminum melt;

[0058] a1. Carry out preliminary degassing and impurity removal, introduce protective gas into the alloy melt, the protective gas is selected as nitrogen or argon, the protective gas introduction amount is set to 36L / min, add RJ-01 refining agent, the refining time is 30min, and the addition amount of solid refining agent is 0.38% of the melt mass; put the aluminum alloy melt after static impurity removal into the degassing box along the flow channel, and install a double-rotor rotary degasser in the degassing box for full online degassing. The rotor is a graphite turntable, and the rotor speed is set to 500r / min. The inert protective gas introduced is argon, the argon pressure is 0.4MPa, and the flow rate is 25L / min

[0059] a2. Add aluminum rare earth boron master alloy, AlMn, AlCr master alloy, and rotate and stir to form B x(FeMnCr) y High density precipitation phase, and let stand for 30 minutes;

[0060] a3. Will not contain B x (FeMnCr) y The solution in the furnace of the high-density precipitation phase is discharged into the clean furnace body for GBF rotary online degassing;

[0061] a4. Insert the electrodes into both ends of the degassing box to perform electromagnetic iron removal to remove smaller iron-containing impurities.

[0062] a5. The aluminum solution after rotary degassing flows through the filter box, and the alloy melt is purified again through the preheated ceramic filter plate, the pore size of the ceramic filter plate is 50ppi; the aluminum solution box is set to have a depth of 800mm, a width of 400mm, a length of 500mm, a temperature of 680-700℃, an operating frequency of 20-50Hz, a current of 20A, a voltage of 220V, an electrode length of 950mm, and a depth of 600-700mm into the aluminum liquid;

[0063] S3, feeding the aluminum solution into a casting forming device for forming, wherein the forming device is selected from a gravity casting machine, a low pressure casting machine or an extrusion casting device;

[0064] S4, heat treating the cast sample;

[0065] b1. Heat in a heat treatment box to 525-535°C and keep warm for 4 hours;

[0066] b2. Perform water quenching, set the water temperature to 50-70°C, and the water quenching time to 10s;

[0067] b3. Drying is carried out, and after drying, the aluminum is put into aging aluminum for aging treatment. The aging temperature is set to 170°C, the aging time is 4.5 hours, and the cooling method after aging is furnace cooling, and the cooling rate is 5°C / min.

[0068] After treatment, the mass fraction ratio of (Fe+Mn+Cr):10*B is 3.2, the total amount of remaining impurities is 0.06wt%, the tensile strength is 340MPa, the yield strength is 250MPa, and the elongation after fracture is 7.0%.

[0069] Example 3

[0070] The present invention provides a low-carbon, environmentally friendly, high-strength and toughness aluminum alloy technical solution: the material composition of the aluminum alloy includes 0.05wt% Cu, 7.4wt% Si, 0.03wt% Zn, 0.06wt% Mn, 0.33wt% Mg, 0.13wt% Fe, 0.015wt% Sr, 0.13wt% Cr, 0.1wt% Ti, 0.0015wt% Ca; 0.0065wt% B, 0.0065wt% Cd, and the balance is Al and 0.03wt% impurities.

[0071] This preparation method specifically comprises the following steps:

[0072] S1. Prepare raw materials according to the aluminum alloy material formula, weigh the corresponding percentage of each raw material for preparation, and after the smelting furnace is dried and preheated, put the prepared raw materials into the furnace in order, and obtain aluminum liquid after hot melting and stirring. Set the drying and preheating temperature to 350°C and the hot melting temperature to 750°C. The order of adding raw materials is: recycled aluminum alloy ingot, Cu element, Mg element, Zn element, Si element, Mn element. After complete melting, add aluminum rare earth boron alloy and AlCd master alloy, and stir for 5 to 15 minutes;

[0073] S2, refining the aluminum melt;

[0074] a1. Carry out preliminary degassing and impurity removal, introduce protective gas into the alloy melt, the protective gas is selected as nitrogen or argon, the protective gas introduction amount is set to 36L / min, add RJ-01 refining agent, the refining time is 30min, and the addition amount of solid refining agent is 0.38% of the melt mass; put the aluminum alloy melt after static impurity removal into the degassing box along the flow channel, and install a double-rotor rotary degasser in the degassing box for full online degassing. The rotor is a graphite turntable, and the rotor speed is set to 500r / min. The inert protective gas introduced is argon, the argon pressure is 0.4MPa, and the flow rate is 25L / min

[0075] a2. Add aluminum rare earth boron master alloy, AlMn, AlCr master alloy, and rotate and stir to form B x (FeMnCr) y High density precipitation phase, and let stand for 30 minutes;

[0076] a3. Will not contain B x (FeMnCr) y The solution in the furnace of the high-density precipitation phase is discharged into the clean furnace body for GBF rotary online degassing;

[0077] a4. Insert the electrodes into both ends of the degassing box to perform electromagnetic iron removal to remove smaller iron-containing impurities.

[0078] a5. The aluminum solution after rotary degassing flows through the filter box, and the alloy melt is purified again through the preheated ceramic filter plate, the pore size of the ceramic filter plate is 50ppi; the aluminum solution box is set to have a depth of 800mm, a width of 400mm, a length of 500mm, a temperature of 680-700℃, an operating frequency of 20-50Hz, a current of 20A, a voltage of 220V, an electrode length of 950mm, and a depth of 600-700mm into the aluminum liquid;

[0079] S3, feeding the aluminum solution into a casting forming device for forming, wherein the forming device is selected from a gravity casting machine, a low pressure casting machine or an extrusion casting device;

[0080] S4, heat treating the cast sample;

[0081] b1. Heat in a heat treatment box to 525-535°C and keep warm for 4 hours;

[0082] b2. Perform water quenching, set the water temperature to 50-70°C, and the water quenching time to 10s;

[0083] b3. Drying is carried out, and after drying, the aluminum is put into aging aluminum for aging treatment. The aging temperature is set to 170°C, the aging time is 4.5 hours, and the cooling method after aging is furnace cooling, and the cooling rate is 5°C / min.

[0084] After treatment, the mass fraction ratio of (Fe+Mn+Cr):10*B is 4.92, the total amount of remaining impurities is 0.04wt%, the tensile strength is 334MPa, the yield strength is 245MPa, and the elongation after fracture is 6.6%.

[0085] Comparative Example 1

[0086] S1. Prepare raw materials according to the aluminum alloy material formula, 0.05wt% Cu, 7.4wt% Si, 0.03wt% Zn, 0.06wt% Mn, 0.33wt% Mg, 0.18wt% Fe, 0.015wt% Sr, 0.13wt% Cr, 0.1wt% Ti, 0.0020wt% Ca; 0.0055wt% B, the balance is Al and 0.03wt% impurities, weigh the corresponding percentages of each raw material for preparation, after the smelting furnace is dried and preheated, put the prepared raw materials into the furnace in sequence, and obtain aluminum liquid after hot melting and stirring. Set the drying and preheating temperature to 350℃, the hot melting temperature to 750℃, and the order of adding raw materials is: recycled aluminum alloy ingot, Cu element, Mg element, Zn element, Si element, Mn element. After complete melting, add aluminum rare earth boron alloy and AlCd master alloy, and the stirring time is 5 to 15 minutes;

[0087] S2, refining the aluminum melt;

[0088] a1. Carry out preliminary degassing and impurity removal, introduce protective gas into the alloy melt, the protective gas is selected as nitrogen or argon, the protective gas introduction amount is set to 36L / min, add RJ-01 refining agent, the refining time is 30min, and the addition amount of solid refining agent is 0.38% of the melt mass; put the aluminum alloy melt after static impurity removal into the degassing box along the flow channel, and install a double-rotor rotary degasser in the degassing box for full online degassing. The rotor is a graphite turntable, and the rotor speed is set to 500r / min. The inert protective gas introduced is argon, the argon pressure is 0.4MPa, and the flow rate is 25L / min

[0089] a2. Add aluminum rare earth boron master alloy, AlMn, AlCr master alloy, and rotate and stir to form B x (FeMnCr) y High density precipitation phase, and let stand for 30 minutes;

[0090] a3. Will not contain B x (FeMnCr) y The solution in the furnace of the high-density precipitation phase is discharged into the clean furnace body for GBF rotary online degassing;

[0091] a4. Insert the electrodes into both ends of the degassing box to perform electromagnetic iron removal to remove smaller iron-containing impurities.

[0092] a5. The aluminum solution after rotary degassing flows through the filter box, and the alloy melt is purified again through the preheated ceramic filter plate, the pore size of the ceramic filter plate is 50ppi; the aluminum solution box is set to have a depth of 800mm, a width of 400mm, a length of 500mm, a temperature of 680-700℃, an operating frequency of 20-50Hz, a current of 20A, a voltage of 220V, an electrode length of 950mm, and a depth of 600-700mm into the aluminum liquid;

[0093] S3, feeding the aluminum solution into a casting forming device for forming, wherein the forming device is selected from a gravity casting machine, a low pressure casting machine or an extrusion casting device;

[0094] S4, heat treating the cast sample;

[0095] b1. Heat in a heat treatment box to 525-535°C and keep warm for 4 hours;

[0096] b2. Perform water quenching, set the water temperature to 50-70°C, and the water quenching time to 10s;

[0097] b3. Drying is carried out, and after drying, the aluminum is put into aging aluminum for aging treatment. The aging temperature is set to 170°C, the aging time is 4.5 hours, and the cooling method after aging is furnace cooling, and the cooling rate is 5°C / min.

[0098] After treatment, the tensile strength is 317MPa, the yield strength is 228MPa, and the elongation after break is 6.5%.

[0099] Comparative Example 2

[0100] S1. Prepare raw materials according to the aluminum alloy material formula, 0.05wt% Cu, 7.4wt% Si, 0.03wt% Zn, 0.06wt% Mn, 0.33wt% Mg, 0.35wt% Fe, 0.015wt% Sr, 0.13wt% Cr, 0.1wt% Ti, 0.0015wt% Ca, 0.0065wt% Cd, 0.1wt% B, the balance is Al and 0.03wt% impurities, weigh the corresponding percentages of each raw material for preparation, after the smelting furnace is dried and preheated, put the prepared raw materials into the furnace in sequence, and obtain aluminum liquid after hot melting and stirring. Set the drying and preheating temperature to 350℃, the hot melting temperature to 750℃, and the order of adding raw materials is: recycled aluminum alloy ingot, Cu element, Mg element, Zn element, Si element, Mn element. After complete melting, add aluminum rare earth boron alloy and AlCd master alloy, and the stirring time is 5 to 15 minutes;

[0101] S2, refining the aluminum melt;

[0102] a1. Carry out preliminary degassing and impurity removal, introduce protective gas into the alloy melt, the protective gas is selected as nitrogen or argon, the protective gas introduction amount is set to 36L / min, add RJ-01 refining agent, the refining time is 30min, and the addition amount of solid refining agent is 0.38% of the melt mass; put the aluminum alloy melt after static impurity removal into the degassing box along the flow channel, and install a double-rotor rotary degasser in the degassing box for full online degassing. The rotor is a graphite turntable, and the rotor speed is set to 500r / min. The inert protective gas introduced is argon, the argon pressure is 0.4MPa, and the flow rate is 25L / min

[0103] a2. Add aluminum rare earth boron master alloy, AlMn, AlCr master alloy, and rotate and stir to form B x (FeMnCr) y High density precipitation phase, and let stand for 30 minutes;

[0104] a3. Will not contain B x (FeMnCr) y The solution in the furnace of the high-density precipitation phase is discharged into the clean furnace body for GBF rotary online degassing;

[0105] a4. Insert the electrodes into both ends of the degassing box to perform electromagnetic iron removal to remove smaller iron-containing impurities.

[0106] a5. The aluminum solution after rotary degassing flows through the filter box, and the alloy melt is purified again through the preheated ceramic filter plate, the pore size of the ceramic filter plate is 50ppi; the aluminum solution box is set to have a depth of 800mm, a width of 400mm, a length of 500mm, a temperature of 680-700℃, an operating frequency of 20-50Hz, a current of 20A, a voltage of 220V, an electrode length of 950mm, and a depth of 600-700mm into the aluminum liquid;

[0107] S3, feeding the aluminum solution into a casting forming device for forming, wherein the forming device is selected from a gravity casting machine, a low pressure casting machine or an extrusion casting device;

[0108] S4, heat treating the cast sample;

[0109] b1. Heat in a heat treatment box to 525-535°C and keep warm for 4 hours;

[0110] b2. Perform water quenching, set the water temperature to 50-70°C, and the water quenching time to 10s;

[0111] b3. Drying, after drying, put it into aging aluminum for aging treatment, set the aging temperature to 170℃, the aging time to 4.5 hours, the cooling method after aging is furnace cooling, and the cooling rate is 5℃ / min. After treatment, the mass fraction ratio of (Fe+Mn+Cr):10*B is 4.92, the total amount of remaining impurities is 0.04wt%, the tensile strength is 340MPa, the yield strength is 230MPa, and the elongation after fracture is 4.5%.

[0112] It can be seen from Comparative Example 1 that adding an appropriate amount of Cd can precipitate during the aging process, play a role in dispersion strengthening, and significantly improve the mechanical properties of the material. It can be seen from Comparative Example 2 that aluminum liquid that has not been subjected to electromagnetic iron removal will result in a high Fe content in the aluminum alloy, forming a needle-shaped AlFeMnCr phase, splitting the matrix, and seriously affecting the toughness of the material. Compared with the existing A356 using pure electrolytic aluminum, the raw materials used in the present invention are wider, and resource recycling can be achieved, thereby reducing carbon emissions.

[0113] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A low-carbon, environmentally friendly, high-strength and tough aluminum alloy, characterized by: The material composition of the aluminum alloy includes 0-0.2wt% Cu, 6.5-8.5wt% Si, 0-0.15wt% Zn, 0.06-0.25wt% Mn, 0.25-0.45wt% Mg, 0-0.25wt% Fe, 0.010-0.025wt% Sr, 0.05-0.2wt% Cr, 0.03-0.15wt% Ti, 0.0040-0.025wt% B, 0.003-0.025wt% Cd, and the balance is Al and 0-0.1wt% impurities.

2. The low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 1, characterized in that: The mass relationship between Fe, Mn and Cr is: 2.5<(Fe+Mn+Cr):10*B<10.5; The aluminum alloy has a tensile strength greater than 320 MPa, a yield strength greater than 240 MPa, and an elongation after fracture greater than 6.0%.

3. A method for preparing a low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to any one of claims 1-2, characterized in that: This preparation method specifically comprises the following steps: S1. Prepare raw materials according to the aluminum alloy material formula, weigh the corresponding percentages of each raw material for preparation, and after the smelting furnace is dried and preheated, put the prepared raw materials into the furnace in order, and obtain aluminum liquid after hot melting and stirring; S2, refining the aluminum melt; S3, feeding the aluminum solution into a casting forming device for forming; S4. heat-treating the cast sample.

4. The method for preparing a low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 3, characterized in that: In step S1, the drying preheating temperature is set to 100-450° C., the hot melting temperature is set to 730-800° C., and the stirring time is set to 5-15 minutes.

5. The method for preparing a low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 3, characterized in that: The step S2 specifically includes the following steps: a1. Carry out preliminary degassing and impurity removal; a2. Add aluminum rare earth boron master alloy, AlMn, AlCr master alloy, and rotate and stir to form B x (FeMnCr) y High density precipitation phase, and let stand for 25 to 35 minutes; a3. Will not contain B x (FeMnCr) y The solution in the furnace of the high-density precipitation phase is discharged into the clean degassing box for GBF rotary online degassing; a4. Insert the electrodes into both ends of the degassing box to perform electromagnetic iron removal to remove smaller iron-containing impurities. a5. The aluminum solution after rotary degassing flows through the filter box, and the alloy melt is purified again through the preheated ceramic filter plate, and the pore size of the ceramic filter plate is 50ppi.

6. The method for preparing a low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 3, characterized in that: In step S3, the molding equipment is selected as a gravity casting machine, a low-pressure casting machine or an extrusion casting equipment.

7. The method for preparing a low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 3, characterized in that: The step S4 specifically comprises the following steps: b1. Heat in a heat treatment box to 525-535°C and keep warm for 4 hours; b2. Perform water quenching, set the water temperature to 50-70°C, and the water quenching time to 20-40s; b3. Drying is carried out, and after drying, the aluminum is put into aging aluminum for aging treatment. The aging temperature is set to 170°C, the aging time is 4.5 hours, and the cooling method after aging is furnace cooling, and the cooling rate is 5°C / min.

8. The method for preparing a low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 5, characterized in that: In the step a1, a protective gas is introduced into the alloy melt, the protective gas is selected to be nitrogen or argon, the amount of the protective gas introduced is set to 0.15-6 L / min, RJ-01 refining agent is added, the refining time is 20-30 min, and the amount of solid refining agent added is 0.2%-0.5% of the melt mass.

9. The method for preparing a low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 5, characterized in that: In the step a1, the aluminum alloy melt after static impurity removal is placed into a degassing box along the flow channel. The degassing box is equipped with a double-rotor rotary degasser for full-line degassing. The rotor is a graphite turntable, and the rotor speed is set to 400-550r / min. The inert protective gas introduced is argon, the argon pressure is 0.3-0.5MPa, and the flow rate is 18-28L / min.

10. The method for preparing a low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 5, characterized in that: In step a5, the aluminum liquid degassing box is set to have a depth of 800 mm, a width of 400 mm, a length of 500 mm, a temperature of 680-700° C., an operating frequency of 20-50 Hz, a current of 20 A, a voltage of 220 V, an electrode length of 950 mm, and a depth of 600-700 mm into the aluminum liquid.

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