A low-carbon, environmentally friendly, high-strength and tough aluminum alloy and its preparation method

Abstract

The present invention discloses a low-carbon, environmentally friendly, high-strength and toughness aluminum alloy and a preparation method thereof. The present invention adds special alloying elements to react, statically filter and remove iron, ceramic filter and remove slag, and electromagnetic iron removal processes to achieve low carbon and environmental protection in the production process of the high-strength and toughness aluminum alloy. At the same time, a reasonable design of Cd promotes the nucleation of second-phase elements, precipitates nano-scale particles, and plays a dispersion strengthening role. Ultimately, a low-carbon, environmentally friendly, high-strength and toughness aluminum alloy material is prepared, which can realize resource recycling and thus reduce carbon emissions.

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. The control of impurity elements such as Fe, Zn, Cu, and Mn in the industrial preparation of this material is extremely strict, making it difficult to choose recycled aluminum as 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 background technology.

[0006] To achieve the above-mentioned objectives, 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 including 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 being 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, and after the melting furnace is dried and preheated, put the prepared raw materials into the furnace in order, melt them, and stir them to obtain aluminum liquid;

[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 melt 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 it 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. The pore size of the ceramic filter plate is 50ppi.

[0022] Preferably, the molding equipment in step S3 is 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 quenching time to 20-40 seconds;

[0026] b3. Dry the aluminum and place it in aging aluminum for aging treatment. Set the aging temperature to 170°C and the aging time to 4.5 hours. The cooling method after aging is furnace cooling at a cooling rate of 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 the protective gas 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 the degassing box along the flow channel, and the degassing box is installed with a dual-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.

[0029] Preferably, in step a5, the aluminum liquid degassing box is set to 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 achieve low carbon and environmental protection in the production process of the high-strength and toughness aluminum alloy by adding special alloy elements to carry out reaction static filtration to remove iron, ceramic filtration to remove slag, and electromagnetic iron removal processes. At the same time, reasonable design of Cd promotes the nucleation of second-phase elements, precipitates nano-scale particles, and plays a dispersion strengthening role. Ultimately, 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 This is a flow chart of the aluminum solution purification process of the present invention. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships 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, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0035] In the description of this patent, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "disposed" should be understood broadly. For example, they can refer to fixed connection or disposition, detachable connection or disposition, or integrated connection or disposition. Those skilled in the art will understand the specific meanings of the above terms in this patent based on the specific circumstances.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "several" means two or more, unless otherwise 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 percentages of each raw material for preparation, and after the drying and preheating of the melting furnace is completed, put the prepared raw materials into the furnace in order, and obtain aluminum melt after heat 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 as follows: recycled aluminum alloy ingot, Cu element, Mg element, Zn element, Si element, and 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. Perform preliminary degassing and impurity removal, introduce protective gas into the alloy melt, the protective gas is selected to be nitrogen or argon, the protective gas introduction rate is set to 36L / min, add RJ-01 refining agent, the refining time is 30min, and the amount of solid refining agent added 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 dual-rotor rotary degasser in the degassing box for full-process 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 it 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 is further purified by a preheated ceramic filter plate with a pore size of 50 ppi. The aluminum solution degassing box is set to 800 mm in depth, 400 mm in width, and 500 mm in length. The temperature is 680-700°C, the operating frequency is 20-50 Hz, the current is 20 A, the voltage is 220 V, the electrode length is 950 mm, and the penetration into the aluminum solution is 600-700 mm.

[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 quenching time to 10 seconds;

[0051] b3. Dry the aluminum and place it in aging aluminum for aging treatment. Set the aging temperature to 170°C and the aging time to 4.5 hours. The cooling method after aging is furnace cooling at a cooling rate of 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 percentages of each raw material for preparation, and after the drying and preheating of the melting furnace is completed, put the prepared raw materials into the furnace in order, and obtain aluminum melt after heat 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 as follows: recycled aluminum alloy ingot, Cu element, Mg element, Zn element, Si element, and 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. Perform preliminary degassing and impurity removal, introduce protective gas into the alloy melt, the protective gas is selected to be nitrogen or argon, the protective gas introduction rate is set to 36L / min, add RJ-01 refining agent, the refining time is 30min, and the amount of solid refining agent added 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 dual-rotor rotary degasser in the degassing box for full-process 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 it 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 is further purified by a preheated ceramic filter plate with a pore size of 50 ppi. The aluminum solution box is set to 800 mm in depth, 400 mm in width, and 500 mm in length. The temperature is 680-700°C, the operating frequency is 20-50 Hz, the current is 20 A, the voltage is 220 V, the electrode length is 950 mm, and the penetration into the aluminum solution is 600-700 mm.

[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 quenching time to 10 seconds;

[0067] b3. Dry the aluminum and place it in aging aluminum for aging treatment. Set the aging temperature to 170°C and the aging time to 4.5 hours. The cooling method after aging is furnace cooling at a cooling rate of 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 percentages of each raw material for preparation, and after the drying and preheating of the melting furnace is completed, put the prepared raw materials into the furnace in order, and obtain aluminum melt after heat 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 as follows: recycled aluminum alloy ingot, Cu element, Mg element, Zn element, Si element, and 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. Perform preliminary degassing and impurity removal, introduce protective gas into the alloy melt, the protective gas is selected to be nitrogen or argon, the protective gas introduction rate is set to 36L / min, add RJ-01 refining agent, the refining time is 30min, and the amount of solid refining agent added 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 dual-rotor rotary degasser in the degassing box for full-process 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 it 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 is further purified by a preheated ceramic filter plate with a pore size of 50 ppi. The aluminum solution box is set to 800 mm in depth, 400 mm in width, and 500 mm in length. The temperature is 680-700°C, the operating frequency is 20-50 Hz, the current is 20 A, the voltage is 220 V, the electrode length is 950 mm, and the penetration into the aluminum solution is 600-700 mm.

[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 quenching time to 10 seconds;

[0083] b3. Dry the aluminum and place it in aging aluminum for aging treatment. Set the aging temperature to 170°C and the aging time to 4.5 hours. The cooling method after aging is furnace cooling at a cooling rate of 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 melt after hot melting and stirring. Set the drying and preheating temperature to 350℃ and the hot melting temperature to 750℃. 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;

[0087] S2, refining the aluminum melt;

[0088] a1. Perform preliminary degassing and impurity removal, introduce protective gas into the alloy melt, the protective gas is selected to be nitrogen or argon, the protective gas introduction rate is set to 36L / min, add RJ-01 refining agent, the refining time is 30min, and the amount of solid refining agent added 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 dual-rotor rotary degasser in the degassing box for full-process 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 it 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 is further purified by a preheated ceramic filter plate with a pore size of 50 ppi. The aluminum solution box is set to 800 mm in depth, 400 mm in width, and 500 mm in length. The temperature is 680-700°C, the operating frequency is 20-50 Hz, the current is 20 A, the voltage is 220 V, the electrode length is 950 mm, and the penetration into the aluminum solution is 600-700 mm.

[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 quenching time to 10 seconds;

[0097] b3. Dry the aluminum and place it in aging aluminum for aging treatment. Set the aging temperature to 170°C and the aging time to 4.5 hours. The cooling method after aging is furnace cooling at a cooling rate of 5°C / min.

[0098] After treatment, the tensile strength is 317MPa, the yield strength is 228MPa, and the elongation at 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 melt after hot melting and stirring. Set the drying and preheating temperature to 350℃ and the hot melting temperature to 750℃. 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;

[0101] S2, refining the aluminum melt;

[0102] a1. Perform preliminary degassing and impurity removal, introduce protective gas into the alloy melt, the protective gas is selected to be nitrogen or argon, the protective gas introduction rate is set to 36L / min, add RJ-01 refining agent, the refining time is 30min, and the amount of solid refining agent added 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 dual-rotor rotary degasser in the degassing box for full-process 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 it 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 is further purified by a preheated ceramic filter plate with a pore size of 50 ppi. The aluminum solution box is set to 800 mm in depth, 400 mm in width, and 500 mm in length. The temperature is 680-700°C, the operating frequency is 20-50 Hz, the current is 20 A, the voltage is 220 V, the electrode length is 950 mm, and the penetration into the aluminum solution is 600-700 mm.

[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 quenching time to 10 seconds;

[0111] b3. Dry the steel and place it in aged aluminum for aging treatment at a temperature of 170°C for 4.5 hours. Cool the steel in the furnace at a rate of 5°C / min. After treatment, the (Fe+Mn+Cr):10*B mass fraction ratio was 4.92, the total residual impurities were 0.04wt%, the tensile strength was 340 MPa, the yield strength was 230 MPa, and the elongation was 4.5%.

[0112] It can be seen from Comparative Example 1 that the addition of an appropriate amount of Cd can precipitate during the aging process, play a dispersion strengthening role, and significantly improve the mechanical properties of the material. It can be seen from Comparative Example 2 that the aluminum liquid without electromagnetic iron removal will lead to 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 to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended 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 0.05-0.2wt% Cu, 6.5-8.5wt% Si, 0.03-0.15wt% Zn, 0.06-0.25wt% Mn, 0.25-0.45wt% Mg, 0.13-0.25wt% 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; The preparation method of the aluminum alloy specifically comprises the following steps: S1. Prepare raw materials according to the aluminum alloy material formula, weigh the corresponding percentages of each raw material, and after the melting furnace is dried and preheated, put the prepared raw materials into the furnace in order, melt them, and stir them to obtain aluminum liquid; S2, refining the aluminum melt; S3, feeding the aluminum solution into a casting forming device for forming; S4, heat treating the cast sample; 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 it stand for 25-35 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; a5. The aluminum solution flows through the filter box and the alloy melt is purified again through the preheated ceramic filter plate with a pore size of 50ppi; The step S4 specifically includes the following steps: b1. Heat in a heat treatment box to 525~535℃ and keep warm for 4 hours; b2. Perform water quenching, set the water temperature to 50~70℃, and the quenching time to 20~40s; b3. Dry the steel sheet and place it in an aging furnace for aging treatment. Set the aging temperature to 170°C and the aging time to 4.5 hours. After aging, the cooling method is furnace cooling at a cooling rate of 5°C / min.

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. The low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 1, characterized in that: In step S1, the drying preheating temperature is set to 100-450° C., the thermal melting temperature is set to 730-800° C., and the stirring time is set to 5-15 minutes.

4. The low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 1, characterized in that: In step S3, the forming equipment is selected as a gravity casting machine, a low-pressure casting machine or an extrusion casting equipment.

5. The low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 1, characterized in that: In the step a1, a protective gas is introduced into the alloy melt, wherein the protective gas is selected from nitrogen or argon, and the protective gas introduction rate is set to 0.15-6 L / min. RJ-01 refining agent is added, and the refining time is 20-30 min. The amount of solid RJ-01 refining agent added is 0.2%-0.5% of the melt mass.

6. A low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 1, characterized in that: In the step a1, the aluminum alloy melt after standing and removing impurities is placed into a degassing box along the flow channel. The degassing box is installed with a dual-rotor rotary degasser for full-line degassing. The rotor is a graphite turntable, and the rotor speed is set to 400~550r / min. Inert protective gas argon is introduced, and the argon pressure is 0.3~0.5MPa and the flow rate is 18~28L / min.

7. The low-carbon, environmentally friendly, high-strength and tough aluminum alloy according to claim 1, characterized in that: In step a5, the aluminum melt tank is set to 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 melt.

Images