High-strength cast aluminum alloy and preparation method thereof
阅读说明：本技术 一种高强度铸造铝合金及其制备方法 (High-strength cast aluminum alloy and preparation method thereof ) 是由 尹文君 赵一钢 陈红伟 王庆云 杨冰儒 向祯晖 何子瑜 常开应 查少雄 白爽 于 2021-06-21 设计创作，主要内容包括：本发明提供一种高强度铸造铝合金及其制备方法,其特征在于由下列质量百分比的组分制成：3.0～6.5% Cu、0.3～1.2% Mn、0.4～1.0% Mg、0.2～1.6%Ag、1.5～3.0%Ti、0.6～1.5%B、0～0.2%稀土元素和余量的Al组成。通过各组分科学、合理的配比,工艺处理,析出强化效果显著的CuAl-(2)相、Al-(2)CuMg过渡相,提高其耐热性,弥散分布的MnAl-(6)相能阻止铝合金的结晶过程和晶粒长大、显著细化晶粒,Ag-Mg原子团的耐热性好,形成非自发核心的TiAl-(2)相,有效细化内部组织,提高铝合金的室温和高温力学性能,使高强度铸造铝合金在室温下的抗拉强度σ-(b)达506MPa,室温硬度HB达147；200℃高温抗拉强度σ-(b)达447MPa,290℃高温抗拉强度σ-(b)达308MPa。(The invention provides a high-strength cast aluminum alloy and a preparation method thereof, which are characterized by being prepared from the following components in percentage by mass: 3.0-6.5% of Cu, 0.3-1.2% of Mn, 0.4-1.0% of Mg, 0.2-1.6% of Ag, 1.5-3.0% of Ti, 0.6-1.5% of B, 0-0.2% of rare earth element and the balance of Al. CuAl with obvious precipitation strengthening effect is separated out through scientific and reasonable proportioning and process treatment of all components 2 Phase, Al 2 CuMg transition phase, improved heat resistance, and dispersed MnAl 6 The phase can prevent the crystallization process and grain growth of the aluminum alloy, obviously refine grains, have good heat resistance of Ag-Mg atomic groups and form TiAl of a non-spontaneous core 2 Effectively refines the internal structure, improves the room-temperature and high-temperature mechanical properties of the aluminum alloy, and ensures that the tensile strength sigma of the high-strength cast aluminum alloy at room temperature b Up to 506MPa, roomThe temperature hardness HB reaches 147; tensile strength sigma at high temperature of 200 DEG C b Reaches 447MPa and high-temperature tensile strength sigma at 290 DEG C b Reaching 308 MPa.)
1. A high-strength cast aluminum alloy is characterized by being prepared from the following components in percentage by mass:
Cu 3.0～6.5%、
Mn 0.3～1.2%、
Mg 0.4～1.0%、
Ag 0.2～1.6%、
Ti 1.5～3.0%、
B 0.6～1.5%、
0 to 0.2 percent of rare earth elements,
The balance of Al,
The sum of the components is 100 percent.
2. The high-strength cast aluminum alloy according to claim 1, wherein the rare earth element is one or any 2 to 3 of Ce, Y, Nd, La, Pr, Er and Sc, and the 2 to 3 elements are mixed in equal proportion.
3. A preparation method of high-strength cast aluminum alloy is characterized by comprising the following steps:
1) preparing materials according to the following mass percent:
Cu 3.0～6.5%、
Mn 0.3～1.2%、
Mg 0.4～1.0%、
Ag 0.2～1.6%、
Ti 1.5～3.0%、
B 0.6～1.5%、
0 to 0.2 percent of rare earth elements,
The balance of Al,
The sum of the components is 100 percent;
the components are aluminum ingot, pure copper, pure manganese, pure magnesium, pure silver, pure titanium, pure boron and rare earth elements;
or Al-Cu intermediate alloy, Al-Mn intermediate alloy, Al-Mg intermediate alloy, Al-Ag intermediate alloy, Al-Ti intermediate alloy, Al-B intermediate alloy;
2) after the aluminum ingot is put into a melting furnace and heated to be melted, adding pure copper, pure manganese, pure silver and rare earth elements in sequence; or adding Al-Cu intermediate alloy, Al-Mn intermediate alloy, Al-Ag intermediate alloy, Al-Ti intermediate alloy and Al-B intermediate alloy, adding a refining agent at the constant temperature of 750-800 ℃, introducing gas, and refining for 5-30 min;
3) when the temperature of the smelting furnace is reduced to 680-720 ℃, adding pure magnesium or Al-Mg intermediate alloy, then heating to 740-780 ℃, adding pure titanium, pure boron or Al-Ti intermediate alloy and Al-B intermediate alloy, and fully stirring for 10-30 min;
4) when the temperature of the smelting furnace is reduced to 680-720 ℃, adding the refining agent again, introducing gas, refining for 5-30 min, and then standing for 5-20 min to obtain an alloy melt;
5) preheating a mould to 150-250 ℃, spraying a release agent on the inner wall of the mould, casting the alloy melt obtained in the step 4) into the mould, and cooling;
6) and 5) cooling the cast formed part in the step 5) to 300-480 ℃, performing three-stage solution treatment, then cooling to 110-140 ℃, performing two-stage aging heat treatment, finally cooling to room temperature along with a furnace, and demolding to obtain the high-strength cast aluminum alloy.
4. The method of claim 3, wherein the aluminum ingot, pure copper, pure manganese, pure magnesium, pure silver, pure titanium, pure boron, and rare earth elements of step 1) are commercially available industrial grade products.
5. The method according to claim 3, wherein the Al-Cu master alloy, the Al-Mn master alloy, the Al-Mg master alloy, the Al-Ag master alloy, the Al-Ti master alloy, and the Al-B master alloy of step 1) are commercially available industrial grade products.
6. The method according to claim 3, wherein the mass ratio of Ag to Mg in the step 1) is controlled to be: Ag/Mg = 0.2-4; controlling the mass ratio of Ti to B as follows: Ti/B =1 ~ 5.
7. The method as claimed in claim 3, wherein the refining agent in the step 2) and the step 4) is hexachloroethane or a chloride salt, and the mass ratio of the hexachloroethane or the chloride salt to the aluminum alloy melt is as follows: the aluminum alloy melt is refined by 400-300: 1.
8. The method of claim 3, wherein the gas introduced in the steps 2) and 4) is argon or nitrogen, and the atmosphere of the furnace is maintained in an argon or nitrogen atmosphere.
9. The method according to claim 3, characterized in that the tertiary solution treatment of step 6) is as follows: preserving heat for 16-24 h at 300-480 ℃, then heating to 500-510 ℃ and preserving heat for 4-16 h, and finally heating to 515-550 ℃ and preserving heat for 4-16 h; through three-stage solution treatment, the quenching temperature of the aluminum alloy can be greatly improved, so that the precipitates in the as-cast aluminum alloy are dissolved in an alpha-Al matrix; meanwhile, the growth of crystal grains is inhibited by controlling the solid solution heating temperature and the heat preservation time.
10. The method according to claim 3, wherein the secondary aging heat treatment of step 6) is specified as follows: preserving heat for 10-20 h at 110-140 ℃, and then heating to 170-200 ℃ and preserving heat for 4-16 h; through secondary aging heat treatment, different strengthening phases are dispersed, precipitated and grown in sequence to form uniformly distributed and multi-scale precipitated phases, and finally the room temperature and high temperature strength of the alloy is improved.
Technical Field
The invention relates to an aluminum alloy and a preparation method thereof, in particular to a high-strength cast aluminum alloy and a preparation method thereof, belonging to the technical field of metallurgical materials.
Background
The aluminum alloy is used as a light commercial metal engineering structural material, has the advantages of high specific strength, large specific elastic modulus, strong corrosion resistance, good processing formability, easy recycling and the like, and is a non-ferrous metal structural material widely applied to the fields of aviation, aerospace, navigation, automobiles, mechanical manufacturing, chemical industry and the like. The aluminum alloy is based on aluminum, and the strength of the aluminum alloy is obviously improved by adding alloying elements such as copper, magnesium, zinc or manganese and the like. The cast aluminum alloy is filled into a casting cavity with molten metal for cooling and forming, has the advantage of small limitation by the structural design of parts, and can be widely used as structural parts with higher requirements on light weight, such as aerospace vehicle shells, underwater vehicle shells, automobile cylinder covers, gearbox shells, instrument and meter shells and the like. The cast AlCu alloy is a cast aluminum alloy with high strength, has the characteristics of high low-density specific strength, good corrosion resistance and casting manufacturability, has the tensile strength of 200-300 MPa, and has the tensile strength of even 450MPa after T5 heat treatment of ZL204A and ZL205A, but has lower hardness (usually HB is less than or equal to 120), and adopts T5 incomplete artificial aging heat treatment, the internal organization structure is in a metastable state, the tensile strength is obviously reduced at high temperature, the requirement of a high-performance cast aluminum alloy material is difficult to meet, particularly along with the development of industrial technology, the service environment of parts is changed, the performance requirement of the material is higher and higher, the material is required to have higher room temperature performance, and the material is required to maintain sufficient mechanical performance under the higher temperature environment. Therefore, the development of high-strength cast aluminum alloy materials is one of the important targets in aluminum alloy development at present.
Disclosure of Invention
The invention provides a high-strength cast aluminum alloy and a preparation method thereof, aiming at solving the problems of low room-temperature hardness, rapid reduction of tensile strength in a high-temperature environment and the like of the existing aluminum alloy.
The invention is completed by the following technical scheme: a high-strength cast aluminum alloy is characterized by being prepared from the following components in percentage by mass:
Cu 3.0～6.5%、
Mn 0.3～1.2%、
Mg 0.4～1.0%、
Ag 0.2～1.6%、
Ti 1.5～3.0%、
B 0.6～1.5%、
0 to 0.2 percent of rare earth elements,
The balance of Al,
The sum of the components is 100 percent.
The rare earth elements are one or 2-3 of Ce, Y, Nd, La, Pr, Er and Sc, and 2-3 are mixed in equal proportion.
The high-strength cast aluminum alloy provided by the invention is prepared by the following steps:
1) preparing materials according to the following mass percent:
Cu 3.0～6.5%、
Mn 0.3～1.2%、
Mg 0.4～1.0%、
Ag 0.2～1.6%、
Ti 1.5～3.0%、
B 0.6～1.5%、
0 to 0.2 percent of rare earth elements,
The balance of Al,
The sum of the components is 100 percent;
the components are aluminum ingot, pure copper, pure manganese, pure magnesium, pure silver, pure titanium, pure boron and rare earth elements;
or Al-Cu intermediate alloy, Al-Mn intermediate alloy, Al-Mg intermediate alloy, Al-Ag intermediate alloy, Al-Ti intermediate alloy, Al-B intermediate alloy;
2) after the aluminum ingot is put into a melting furnace and heated to be melted, adding pure copper, pure manganese, pure silver and rare earth elements in sequence; or adding Al-Cu intermediate alloy, Al-Mn intermediate alloy, Al-Ag intermediate alloy, Al-Ti intermediate alloy and Al-B intermediate alloy, adding a refining agent at the constant temperature of 750-800 ℃, introducing gas, and refining for 5-30 min;
3) when the temperature of the smelting furnace is reduced to 680-720 ℃, adding pure magnesium or Al-Mg intermediate alloy, then heating to 740-780 ℃, adding pure titanium, pure boron or Al-Ti intermediate alloy and Al-B intermediate alloy, and fully stirring for 10-30 min;
4) when the temperature of the smelting furnace is reduced to 680-720 ℃, adding the refining agent again, introducing gas, refining for 5-30 min, and then standing for 5-20 min to obtain an alloy melt;
5) preheating a mould to 150-250 ℃, spraying a release agent on the inner wall of the mould, casting the alloy melt obtained in the step 4) into the mould, and cooling;
6) and 5) cooling the cast formed part in the step 5) to 300-480 ℃, performing three-stage solution treatment, then cooling to 110-140 ℃, performing two-stage aging heat treatment, finally cooling to room temperature along with a furnace, and demolding to obtain the high-strength cast aluminum alloy.
The aluminum ingot, the pure copper, the pure manganese, the pure magnesium, the pure silver, the pure titanium, the pure boron and the rare earth element obtained in the step 1) are commercial industrial-grade products.
The Al-Cu intermediate alloy, the Al-Mn intermediate alloy, the Al-Mg intermediate alloy, the Al-Ag intermediate alloy, the Al-Ti intermediate alloy and the Al-B intermediate alloy in the step 1) are commercial industrial products.
Preferably, the mass ratio of Ag to Mg in the step 1) is controlled as follows: Ag/Mg = 0.2-4.
Preferably, in the step 1), the mass ratio of Ti to B is controlled as follows: Ti/B =1 ~ 5.
The refining agent in the step 2) and the step 4) is hexachloroethane or chloride salt, and the mass ratio of the hexachloroethane or chloride salt to the aluminum alloy melt is as follows: the aluminum alloy melt is refined by 400-300: 1.
The gas introduced in the step 2) and the step 4) is argon or nitrogen, and the atmosphere of the smelting furnace is kept to be argon or nitrogen.
The three-stage solution treatment is as follows: preserving heat for 16-24 h at 300-480 ℃, then heating to 500-510 ℃ and preserving heat for 4-16 h, and finally heating to 515-550 ℃ and preserving heat for 4-16 h; through three-stage solution treatment, the quenching temperature of the aluminum alloy can be greatly improved, so that the precipitates in the as-cast aluminum alloy are dissolved in an alpha-Al matrix; meanwhile, the growth of crystal grains is inhibited by controlling the solid solution heating temperature and the heat preservation time.
The secondary aging heat treatment is as follows: preserving heat for 10-20 h at 110-140 ℃, and then heating to 170-200 ℃ and preserving heat for 4-16 h; through secondary aging heat treatment, different strengthening phases are dispersed, precipitated and grown in sequence to form uniformly distributed and multi-scale precipitated phases, and finally the room temperature and high temperature strength of the alloy is improved.
The release agent in the step 5) is a conventional product.
The invention comprises the following steps:
3.0-6.5% of Cu in the high-strength cast aluminum alloy can precipitate CuAl through aging2The phase has obvious aging strengthening effect and certain solid solution strengthening effect. Forming GP zone and fine precipitate by aging, strengthening the aluminum alloy and forming Al2The strengthening effect is maximum due to the CuMg transition phase. At the same time, Al2The CuMg transition phase has better heat resistance;
0.3-1.2% of Mn in the high-strength cast aluminum alloy can form dispersed MnAl6The phase can prevent the crystallization process and grain growth of the aluminum alloy and obviously refine grains;
0.2-1.6% of Ag in the high-strength cast aluminum alloy can be segregated at the interface, is easy to react with Mg to form Ag-Mg atomic groups, and has better heat resistance;
1.5-3.0% of Ti and 0.6-1.5% of B in the high-strength cast aluminum alloy, wherein the titanium can form TiAl with aluminum2The phase becomes a non-spontaneous core during crystallization and plays a role in refining internal tissues; in which B is capable of forming tiny TiB2A particle strengthening phase;
0-0.2% of rare earth elements in the high-strength cast aluminum alloy play a role in refining grains and enhancing mechanical properties.
The invention has the following advantages and effects: by adopting the scheme, the CuAl with remarkable strengthening effect is separated out through scientific and reasonable proportioning of all components, especially control of the proportion of Ag/Mg and Ti/B in the alloy, and then three-stage solid solution and two-stage aging heat treatment2Phase, Al2CuMg transition phase, improves the heat resistance of the aluminum alloy, forms MnAl which can prevent the crystallization process and the grain growth of the aluminum alloy and obviously refine the dispersion distribution of the grains6Phase of TiAl, which forms Ag-Mg atomic group with good heat resistance and can become non-spontaneous core when forming crystal2Phase, refining the internal structure, forming tiny TiB2The particle strengthening phase improves the room temperature and high temperature mechanical properties of the aluminum alloy, and leads the tensile strength sigma of the high-strength cast aluminum alloy at room temperatureb506MPa, and the room temperature hardness HB reaches 147; tensile strength sigma at high temperature of 200 DEG CbReaches 447MPa and high-temperature tensile strength sigma at 290 DEG CbReaching 308 MPa.
Drawings
FIG. 1 is a graph of the high temperature performance of the high strength cast aluminum alloy of example 1.
FIG. 2 is a microstructure of the high strength cast aluminum alloy of example 1.
FIG. 3 is a microstructure of the high strength cast aluminum alloy of example 2.
Detailed Description
The present invention is further described below by way of examples, but the technical solution of the present invention is not limited to the examples listed below, and includes any combination between the specific embodiments.
The apparatuses not specifically described in the present invention are conventional apparatuses.
Example 1
A method for preparing a high strength cast aluminum alloy comprising the steps of:
1. preparing the following raw materials in percentage by mass: 6.5% Cu, 1.2% Mn, 0.4% Mg, 1.6% Ag, 3.0% Ti, 0.6% B, 0.2% Ce and 86.5% Al; wherein the raw materials are as follows: aluminum ingot, pure copper, pure magnesium, pure silver, rare earth element cerium, Al-Mn intermediate alloy, Al-Ti intermediate alloy and Al-B intermediate alloy; and the mass ratio of Ag to Mg is Ag/Mg-4; the mass ratio of Ti to B is that Ti/B is 5;
2. putting an aluminum ingot into a furnace, heating to melt, sequentially adding pure copper, pure silver, rare earth element cerium and Al-Mn intermediate alloy, adding hexachloroethane and introducing argon, keeping the furnace in an argon atmosphere, and refining at 750 ℃ for 30min, wherein: the mass ratio of hexachloroethane to the aluminum alloy solution is as follows: aluminum alloy melt, refining agent =300: 1;
3. reducing the temperature of the smelting furnace to 720 ℃, adding pure magnesium, subsequently heating to 740 ℃, adding Al-Ti intermediate alloy and Al-B intermediate alloy, and fully stirring for 30 min;
4. when the temperature of the smelting furnace is reduced to 680 ℃, adding hexachloroethane again, introducing argon, keeping the smelting furnace in an argon atmosphere, refining for 30min, synchronizing the mass ratio of hexachloroethane to the alloy melt in step 2, and then standing for 20min to obtain an alloy melt;
5. preheating a mould to 250 ℃, spraying a conventional release agent on the inner wall of the mould, casting the alloy melt obtained in the step 4) into the mould, and cooling;
6. cooling the casting to 450 ℃, preserving heat for 16h, then heating to 510 ℃, preserving heat for 4h, and finally heating to 550 ℃, preserving heat for 4 h;
7. and (3) cooling the casting to 140 ℃, preserving heat for 10h, then heating to 195 ℃, preserving heat for 4h, finally cooling to room temperature along with the furnace, and demolding to obtain the high-strength cast aluminum alloy, wherein the room temperature mechanical properties are as follows: tensile Strength σb=506MPa, yield strength sigma0.2=467MPa, E =77.2GPa, HB =147 hardness, and delta elongation5= 4.2%. High temperature performance: tensile strength sigma at high temperature of 200 DEG Cb=447MPa, 290 ℃ high temperature tensile strength sigmab=308MPa, as shown in fig. 1, and the microstructure is shown in fig. 2.
Example 2
The preparation method of the high-strength cast aluminum alloy comprises the following steps:
1. preparing the following raw materials in percentage by mass: 3.0% Cu, 0.3% Mn, 1.0% Mg, 0.2% Ag, 3.0% Ti, 1.5% B, and 91% Al; wherein the raw materials are as follows: aluminum ingot, pure magnesium, pure silver, pure titanium, pure boron and Al-Cu master alloy, Al-Mn master alloy, Al-Ti master alloy, Al-B master alloy; and the mass ratio of Ag to Mg is Ag/Mg-0.2; the mass ratio of Ti to B is that Ti/B is 1;
2. putting an aluminum ingot into a melting furnace, heating to melt, sequentially adding pure silver, pure titanium, pure boron, Al-Cu intermediate alloy and Al-Mn intermediate alloy, adding hexachloroethane, introducing nitrogen, and refining at 800 ℃ for 5min, wherein: the mass ratio of hexachloroethane to the alloy solution is 400: 1;
3. cooling the furnace to 700 ℃, adding pure magnesium, subsequently heating to 780 ℃, adding Al-Ti intermediate alloy and Al-B intermediate alloy, and fully stirring for 10 min;
4. when the temperature of the smelting furnace is reduced to 720 ℃, adding hexachloroethane again, introducing nitrogen, refining for 5min, wherein the mass ratio of hexachloroethane to the alloy melt is 400:1, and then standing for 5min to obtain an alloy melt;
5. preheating a mould to 150 ℃, spraying a conventional release agent on the inner wall of the mould, casting the alloy melt obtained in the step 4) into the mould, and cooling;
6. cooling the casting to 300 ℃, preserving heat for 24h, then heating to 500 ℃, preserving heat for 16h, and finally heating to 515 ℃, preserving heat for 16 h;
7. and (3) cooling the casting to 110 ℃, preserving heat for 20h, then heating to 170 ℃, preserving heat for 16h, finally cooling to room temperature along with the furnace, and demolding to obtain the high-strength cast aluminum alloy, wherein the room temperature mechanical properties are as follows: tensile Strength σb=477MPa, yield strength sigma0.2=454MPa, elastic modulus E =72.2GPa, hardness HB =146, elongation δ5= 2.0%. High temperature performance: tensile strength sigma at high temperature of 200 DEG Cb=345MPa, 290 ℃ high temperature tensile strength sigmab=264MPa, and the microstructure is shown in FIG. 3.
Example 3
The preparation method of the high-strength cast aluminum alloy comprises the following steps:
1. preparing the following raw materials in percentage by mass: 4.8% Cu, 0.5% Mn, 0.8% Mg, 0.6% Ag, 2.5% Ti, 1.0% B, 0.2% Y, 0.2% Nd, and 89.4% Al; wherein the raw materials are as follows: aluminum ingot, pure copper, pure manganese, pure magnesium, pure silver, pure titanium, pure boron, rare earth elements yttrium and neodymium; the mass ratio of Ag to Mg is that Ag/Mg is 0.75; the mass ratio of Ti to B is 2.5;
2. putting an aluminum ingot into a melting furnace, heating to melt, sequentially adding pure copper, pure manganese, pure silver, rare earth elements of yttrium and neodymium, preserving heat at 780 ℃, adding hexachloroethane, introducing argon, and refining for 15min, wherein: the mass ratio of hexachloroethane to the alloy solution is 350: 1;
3. reducing the temperature of the smelting furnace to 710 ℃, adding pure magnesium, subsequently heating to 750 ℃, adding pure titanium and pure boron, and fully stirring for 20 min;
4. when the temperature of the smelting furnace is reduced to 700 ℃, adding hexachloroethane again, introducing argon, and refining for 15min, wherein: the mass ratio of hexachloroethane to the alloy melt is 350:1, and then standing for 15min to obtain an alloy melt;
5. preheating a mould to 200 ℃, spraying a conventional release agent on the inner wall of the mould, casting the alloy melt obtained in the step 4) into the mould, and cooling;
6. cooling the casting to 400 ℃, preserving heat for 20h, then heating to 505 ℃, preserving heat for 10h, and finally heating to 525 ℃ and preserving heat for 10 h;
7. when the casting is cooled to 130 ℃, the temperature is kept 1And 4h, heating to 185 ℃, preserving heat for 8h, cooling to room temperature along with the furnace, and demolding to obtain the high-strength cast aluminum alloy, wherein the room temperature mechanical properties are as follows: tensile Strength σb=492MPa, yield strength sigma0.2=456MPa, modulus of elasticity E =73.6GPa, hardness HB =144, elongation delta5= 4.4%. High temperature performance: tensile strength sigma at high temperature of 200 DEG CbTensile strength sigma at high temperature of 290 ℃ of =360MPab=277MPa。