CN112795856A - Heat treatment method for cast aluminum alloy casting and cast aluminum alloy casting obtained by heat treatment method - Google Patents
Heat treatment method for cast aluminum alloy casting and cast aluminum alloy casting obtained by heat treatment method Download PDFInfo
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- CN112795856A CN112795856A CN202011562769.4A CN202011562769A CN112795856A CN 112795856 A CN112795856 A CN 112795856A CN 202011562769 A CN202011562769 A CN 202011562769A CN 112795856 A CN112795856 A CN 112795856A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/043—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with silicon as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/026—Alloys based on aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/03—Making non-ferrous alloys by melting using master alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C21/00—Alloys based on aluminium
- C22C21/02—Alloys based on aluminium with silicon as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
Abstract
The invention provides a heat treatment method for a cast aluminum alloy casting and the cast aluminum alloy casting obtained by the heat treatment method. The invention comprises the following steps: 1) performing solution treatment for 1-2 h at 525-535 ℃; heating to 535-545 ℃, carrying out vacuum degassing treatment for 6-8 h, and cooling by water; 2) aging for 3-4 h at 200-210 ℃; 3) performing solution treatment for 1-2 h at 525-535 ℃; heating to 535-545 ℃, carrying out solution treatment for 6-8 h, and cooling by water; 4) carrying out cryogenic treatment for 1-2 h at-110 to-120 ℃; aging at 140-150 ℃ for 5-6 h; carrying out cryogenic treatment for 1-2 h at-110 to-120 ℃; and (3) carrying out aging treatment for 10-12 h at 140-150 ℃, and air cooling. The invention has the advantages of more uniform solute atom distribution, more dispersed and finer precipitated phase and more compact structure, and improves the fatigue property and the comprehensive mechanical property of the casting.
Description
Technical Field
The invention relates to the technical field of aluminum alloy post-treatment, in particular to a heat treatment method for a cast aluminum alloy casting and the cast aluminum alloy casting obtained by the heat treatment method.
Background
Cast aluminum alloy (Cast aluminum alloy) can be directly obtained from an aluminum alloy of a part by a metal casting forming process, has the advantages of small density, high strength, simple production process, low cost and the like, is widely applied to national industry at present, and the application field covers the fields of aviation, aerospace, electronics, ships, weapons, high-speed rails and the like. With the continuous progress of modern industry, the performance requirements of various industries on cast aluminum alloy are higher and higher, especially in the fields of aviation, high-speed iron and high-speed maglev trains, which generally require that the cast aluminum alloy has good reliability, especially fatigue performance.
The performance of the cast aluminum alloy is mainly determined by the chemical components, the smelting process, the pouring conditions, the heat treatment process and the like, wherein the heat treatment is an important way for improving the performance of the cast aluminum alloy. At present, the reliability of the cast aluminum alloy is usually realized by some complex post-treatment processes, the performance of the cast aluminum alloy is not basically improved due to the unreasonable process design of the post-treatment method, and the obtained cast aluminum alloy has poor reliability, low fatigue performance and insufficient mechanical property and can not meet the requirements in the fields of aviation, high-speed rails and high-speed maglev trains.
Disclosure of Invention
The invention aims to provide a heat treatment method of a cast aluminum alloy casting and the cast aluminum alloy casting obtained by the heat treatment method, and aims to solve the problem that the performance of the cast aluminum alloy is basically not improved due to the unreasonable design of the heat treatment process of the cast aluminum alloy in the prior art, so that the cast aluminum alloy has poor reliability, low fatigue performance and insufficient mechanical properties, and thus cannot meet the requirements of the fields of aviation, high-speed trains and high-speed maglevs.
In order to solve the technical problem, the technical scheme of the invention is realized as follows:
in one aspect, the present invention is a heat treatment method for casting an aluminum alloy casting, comprising the steps of: 1) placing a cast aluminum alloy casting to be treated at 525-535 ℃, and carrying out solid solution treatment for 1-2 h; heating to 535-545 ℃, carrying out vacuum degassing treatment for 6-8 h, and carrying out water cooling to obtain a first water quenching casting; 2) placing the first water quenched casting obtained in the step 1) at 200-210 ℃, and performing aging treatment for 3-4 hours to obtain an aged casting; 3) placing the aging casting obtained in the step 2) at 525-535 ℃ again, and carrying out solid solution treatment for 1-2 h; heating to 535-545 ℃, carrying out solution treatment for 6-8 h, and carrying out water cooling to obtain a second water quenching casting; 4) placing the secondary water-quenched casting obtained in the step 3) at-110 to-120 ℃ and carrying out cryogenic treatment for 1 to 2 hours; then, placing the mixture at 140-150 ℃ for aging treatment for 5-6 h; placing the mixture at-110 to-120 ℃ again, and carrying out cryogenic treatment for 1 to 2 hours; and then, placing the aluminum alloy casting at 140-150 ℃, carrying out aging treatment for 10-12 h, and carrying out air cooling to obtain the cast aluminum alloy casting.
According to the heat treatment method for casting the aluminum alloy casting, firstly, the casting is subjected to high-temperature solid solution, and high-temperature pretreatment is set in advance during solid solution, so that destructive influence on the casting caused by furnace temperature impact is avoided; the casting is subjected to solid-state vacuum degassing treatment while carrying out first high-temperature solid solution, and because the hydrogen partial pressure in the vacuum environment is low, the hydrogen atoms dissolved in the casting matrix are gradually diffused to the surface of the casting to form hydrogen gas based on a partial pressure difference diffusion mechanism and are pumped out, so that a large number of vacancies are formed in crystal lattices, and an obvious dehydrogenation effect is also achieved. For aluminum alloy, hydrogen atoms existing in a matrix can diffuse to crystal lattices in the heat treatment process, and grain boundary segregation occurs, so that the grain boundary is weakened, and the fatigue performance of a casting is seriously influenced; the invention reduces the content of hydrogen in the casting and has obvious beneficial effect on improving the fatigue performance and reliability of the casting. Then, the casting is subjected to high-temperature aging treatment after the first water quenching, so that the rapid and full precipitation of precipitated phases is facilitated; during the second high-temperature solid solution treatment, the precipitated phase which is uniformly precipitated can be more fully redissolved to the matrix, and at the moment, solute atoms redissolved to the matrix are more thorough and are more uniformly distributed, so that subsequent time-effect phase dispersion spheroidization precipitation is facilitated. In addition, after the second water quenching, the subzero cryogenic treatment and the subzero aging treatment of the casting are alternately carried out, in the process of the alternate treatment, the casting is influenced by thermal expansion and cold contraction, tensile and compressive stress is generated in the casting to cause the casting to generate micro deformation, the casting releases a large amount of residual stress through the micro deformation, and most of micro defects are compacted to achieve the densification effect of the casting, so that the fatigue property of the casting can be further improved; meanwhile, the matrix is subjected to microscopic deformation in the cryogenic treatment process, so that more uniform dislocation is generated in the matrix, and the dispersion and precipitation of a precipitated phase are facilitated. And finally, performing low-temperature aging treatment on the casting, wherein the low-temperature aging treatment can obviously improve the precipitation power of solute atoms, and in the early stage of low-temperature heat preservation, vacancies and dislocations provide effective initial nucleation positions of precipitated phases, so that the volume fraction of the precipitated phases is greatly improved, and precipitated strengthening phases are more dispersed, the size is finer, the strengthening effect is higher, and the comprehensive mechanical property is better. The heat treatment method for the cast aluminum alloy casting obviously improves the reliability of the casting, improves the fatigue property of the casting, improves the comprehensive mechanical property of the casting, meets the performance requirements of the fields of aviation, high-speed rail and high-speed maglev trains on the cast aluminum alloy casting, expands the application range of the cast aluminum alloy casting, and can be widely applied to the fields of aviation, high-speed rail, high-speed maglev trains and the like.
In a preferable embodiment, in the step 3), the air cooling is performed at an air temperature of 10 to 40 ℃ to room temperature. The air cooling is natural cooling at room temperature, the temperature of the room temperature is usually 10-40 ℃, and the temperature of the casting after the room temperature cooling also reaches 10-40 ℃; the air cooling can realize quick cooling, reduce unnecessary time occupied by the aging furnace and improve the treatment efficiency.
In a preferable embodiment, in the step 2), the temperature of water is 60 to 80 ℃ during water cooling, and the water cooling time is 100 to 160 s. According to the water cooling method, the casting is placed in water for cooling, the casting is immersed in the water, and the crown block controls the casting to move up and down in the water but not to expose out of the water surface, so that the casting is rapidly and fully cooled; the cooling speed of water cooling is high, thereby being beneficial to the rapid change of the internal structure of the casting and the subsequent treatment.
As a preferred embodiment, in the step 2), a temperature-programmed manner is adopted in the temperature-raising process, and the temperature-raising speed is 4-6 ℃/min. The high-temperature solid solution is carried out in two steps, firstly, the solid solution is carried out at low temperature of 525-535 ℃, and then the solid solution is carried out at high temperature of 535-545 ℃; the two-step solid solution method can activate solute atoms in the casting in advance, and then the solute atoms start to move greatly when solid solution is carried out at high temperature, so that the solute atoms move freely, and the damage of the casting structure caused by overhigh temperature is avoided.
As a preferred embodiment, in the step 1), the pressure in the furnace chamber is 10 during the vacuum degassing treatment-4～10-5Pa. The vacuum degassing treatment is carried out while the casting is subjected to the first solid solution, and hydrogen atoms in the casting are removed under the vacuum condition, at the moment, the lower the environmental pressure of the furnace chamber is, the larger the vacuum degree is, the higher the power for extracting the hydrogen atoms is, and the easier the hydrogen atoms are to be extracted; the control of the environmental pressure of the furnace chamber is easy and convenient.
As a preferred embodiment, in the step 1), the temperature of water is 60 to 80 ℃ during water cooling, and the water cooling time is 100 to 160 s. In the invention, the casting is subjected to water cooling treatment twice, namely water quenching; after the casting is subjected to high-temperature solid solution, water quenching is needed, and the operation steps of the water quenching are the same; the water quenching cooling speed is fast, the realization is easy, the cost is low, and the surface of the casting can not be polluted.
As a preferred embodiment, in the step 1), a temperature-programmed manner is adopted in the temperature-raising process, and the temperature-raising speed is 4-6 ℃/min. The casting is subjected to high-temperature solution treatment twice, and the operation of the high-temperature solution treatment twice is the same; in the two-step solid solution process, the solid solution temperature gradually reaches the requirement by adopting a temperature programming method, the temperature is slowly increased by adopting the temperature programming method, the damage to the casting caused by overhigh temperature is avoided, meanwhile, the operation time is effectively controlled, the heat treatment efficiency is improved, and the internal structure of the casting is more stable.
In another aspect, a cast aluminum alloy casting of the present invention is treated according to the heat treatment method for a cast aluminum alloy casting described in any one of the above.
The cast aluminum alloy casting is subjected to high-temperature solid solution twice, water cooling is carried out between the two high-temperature solid solutions, and high-temperature aging is also carried out between the two high-temperature solid solutions; finally, carrying out ultralow temperature subzero treatment and low temperature aging treatment alternately for two times, and air cooling to obtain a cast aluminum alloy casting; in the process of repeated solid solution, water cooling, deep cooling and aging treatment, the internal structure of the casting is obviously changed, the content of hydrogen in the casting is reduced, the integral structure of the casting is more compact, the reliability of the casting is improved, the fatigue property of the casting is improved, and the comprehensive mechanical property of the casting is improved.
As a preferred embodiment, the cast aluminum alloy casting comprises the following components in weight percent: 4.5 to 5.5 percent of Si, 0.3 to 0.4 percent of Mg, 0.05 to 0.20 percent of Sb, 0.08 to 0.13 percent of Ti, 0.006 to 0.06 percent of Zr, the total content of impurities is not more than 0.1 percent, and the balance is aluminum. The cast aluminium alloy casting of the invention is an aluminium-silicon alloy, such aluminiumThe silicon alloy also contains magnesium, antimony, titanium and zirconium elements which are matched with each other, and Sb atoms or Mg-Sb phases are adsorbed on the surface of the silicon phase in the heat treatment process, so that the coarsening and growth of the silicon phase are effectively inhibited; nanoscale Al3Ti and Al3Zr or Al3The (Ti, Zr) precipitated phase can effectively pin the grain boundary and inhibit the growth of grains and sub-grains in the heat treatment process; meanwhile, the precipitated phases can effectively pin dislocation, block dislocation movement, improve the strength of the matrix and improve the thermal stability of the alloy to a certain extent.
As a preferred embodiment, the impurities comprise the following elements in weight percent: fe is less than or equal to 0.07 percent, Sn is less than or equal to 0.02 percent, and Pb is less than or equal to 0.01 percent. The impurities of the invention are mainly derived from raw materials of elements, the content of the impurities is better, and the impurities are iron elements, tin elements and lead elements; in the cast aluminum alloy casting, when the iron content is high, the iron element and aluminum easily form a thick and thick indissolvable strip compound, and a matrix is cut in the stretching process, so that the strength and the elongation of the alloy are reduced; when the content of tin or lead element exceeds 0.05%, tin atoms and lead atoms enter the middle of aluminum atoms, the average atomic distance of the aluminum atoms is increased, stress is generated on the surface layer of the crystal, and the elastic modulus and the elongation of the alloy are also reduced.
In yet another aspect, a method of making a cast aluminum alloy casting includes the steps of: a) firstly, heating a smelting furnace to raise the temperature of the furnace to 300-400 ℃, and keeping the temperature for 10-15 min; then, adding a raw material containing an Al element, a raw material containing an Si element, a raw material containing an Sb element, a raw material containing a Ti element and a raw material containing a Zr element, continuously heating and melting, raising the temperature of the melting furnace to 800-830 ℃, preserving the heat for 20-30 min, and stirring for 5-10 min to obtain an aluminum alloy melt; b) cooling, namely cooling the temperature of the smelting furnace to 700-710 ℃, adding a refining agent A, wherein the refining agent A is hexachloroethane, the addition amount of the refining agent A is 0.4-0.6% of the total weight of the aluminum alloy melt, and stirring for 5-10 min; c) keeping the temperature of the smelting furnace at 700-710 ℃, adding a raw material containing Mg, stirring for 3-5 min, and adding a refining agent B, wherein the refining agent B comprises the following components in percentage by weight: 50-55% of hexachloroethane, 18-20% of aluminum oxide, 18-20% of titanium trioxide, 4-5% of zirconium dioxide and 4-5% of calcium oxide, wherein the addition amount of the refining agent B is 0.1-0.2% of the total weight of the aluminum alloy melt, stirring for 5-10 min, standing for 20-30 min, and pouring to obtain the cast aluminum alloy casting to be treated.
The preparation method of the cast aluminum alloy casting comprises the steps of firstly heating a smelting furnace, adding raw materials containing aluminum, silicon, antimony, titanium and zirconium elements, and then heating to melt the raw materials; then, adding a single refining agent A for refining; finally, adding a raw material containing magnesium and a combined refining agent B, refining again, standing and pouring to obtain a cast aluminum alloy casting; the aluminum, silicon, antimony, titanium and zirconium elements are firstly refined under the action of hexachloroethane, then the magnesium element is added for refining, and finally the combined refining agent is added for refining again. When the refining agent A is singly added, the refining agent reacts more violently, bubbles generated by the reaction are large, and oxide inclusions and hydrogen atoms in the melt are brought out to the surface of the melt in the floating process of the bubbles; when the refining agent B is added, the oxide in the refining agent can inhibit the reaction speed of hexachloroethane and slightly increase the viscosity of the melt, bubbles generated by the reaction are slightly small, the rising speed is relatively slow, the refining efficiency is improved, and oxide inclusions and hydrogen atoms with small sizes are further brought out to the surface of the melt in the bubble floating process; the two refining agents are used in a combined way, so that the oxide inclusions and hydrogen in the aluminum melt are further reduced, and the purity of the melt is further improved; in addition, the refining agent A is added and then the magnesium is added, so that the burning loss of the magnesium element is effectively reduced, the refining effect is good, the cost is reduced, and meanwhile, the content of the magnesium element can be accurately controlled; the preparation method of the cast aluminum alloy casting is simple to operate, low in cost, easy to master and easy to realize industrialization.
As a preferred embodiment, in the step 1), the raw material containing the Al element is pure aluminum metal; in the step 3), the raw material containing Mg element is pure magnesium metal. In the invention, the aluminum element is used as a matrix, the content of the aluminum element is the maximum, and the aluminum element is added in a pure metal form; because magnesium metal is easy to obtain and has relatively stable performance, the magnesium element is also added in the form of pure metal; the pure metal has wide source, low price, easy obtaining and convenient use.
As a preferred embodiment, the purity of the pure aluminum metal is not less than 99.993%, and the purity of the pure magnesium metal is not less than 99.95%. The pure metal aluminum is Al99.993, and the element content requirement meets the GB/T8644-2000 requirement; the pure magnesium metal is Mg99.95, and the element content requirement meets the GB/T3499-1995 requirement; the impurity elements of the obtained cast aluminum alloy casting are controlled by strictly controlling the purity of each element raw material, so that the performance of the cast aluminum alloy casting is improved.
In a preferred embodiment, in the step 1), the Si-containing material is a silicon alloy, the Sb-containing material is an antimony alloy, the Ti-containing material is a titanium alloy, and the Zr-containing material is a zirconium alloy. According to the invention, the raw materials of the elements of silicon, antimony, titanium and zirconium are added in the form of the master alloy, and because the content of the elements of silicon, antimony, titanium and zirconium is low, the elements of silicon, antimony, titanium and zirconium added in the form of the master alloy are easy to mix with the raw materials of other elements, so that the mixing uniformity is improved, and further the comprehensive performance of the cast aluminum alloy casting is improved.
In a preferred embodiment, the silicon alloy is AlSi12, the antimony alloy is AlSb4, the titanium alloy is AlTi4, and the zirconium alloy is AlZr 4. The silicon alloy AlSi12 meets the requirement of GB/T27677-2011 on the element content; the antimony alloy AlSb4 meets the requirement of GB/T27677-2011 on element content; the titanium alloy AlTi4 of the invention meets the requirement of GB/T27677-2011 on element content; the zirconium alloy AlZr4 meets the requirement of GB/T27677-2011 on the element content; the silicon intermediate alloy is an aluminum-silicon alloy, the antimony intermediate alloy is an aluminum-antimony alloy, the titanium intermediate alloy is an aluminum-titanium alloy, the zirconium intermediate alloy is an aluminum-zirconium alloy, and the intermediate alloys do not contain elements irrelevant to the cast aluminum alloy casting, so that the purity of the cast aluminum alloy casting is further improved.
Compared with the prior art, the invention has the beneficial effects that: during vacuum degassing treatment, hydrogen atoms dissolved in a casting matrix diffuse to the surface of the casting to form hydrogen gas which is pumped away, and vacancies are formed in crystal lattices, so that the obvious dehydrogenation effect is achieved, the content of hydrogen in the casting is reduced, the fatigue performance of the casting is improved, and the reliability of the casting is improved; the high-temperature solid solution, the high-temperature aging, the cryogenic treatment and the low-temperature aging are organically combined, a precipitated phase is rapidly, fully and uniformly precipitated during the high-temperature aging, the uniformly precipitated phase is fully re-dissolved to a matrix again during the high-temperature solid solution, and solute atoms re-dissolved to the matrix are more uniformly distributed, so that the subsequent aging precipitation is facilitated; the cold and hot temperature are alternately treated, the tensile stress and the compressive stress are generated in the casting to enable the casting to generate micro deformation, most of micro defects are compacted while the casting releases a large amount of residual stress, the casting densification effect is achieved, and the fatigue performance of the casting is further improved; during low-temperature aging treatment, the precipitation power of solute atoms in the matrix is increased, a large number of dislocations and vacancies are used as initial nucleation positions of a precipitated phase, the volume fraction of the precipitated phase is larger, the formed precipitated phase is more dispersed, the size is smaller, the strengthening effect is better, and the comprehensive mechanical property is better. The cast aluminum alloy casting obtained by the invention meets the performance requirements of the fields of aviation, high-speed rail and high-speed maglev trains on the cast aluminum alloy casting, expands the application range of the cast aluminum alloy casting, and can be widely applied to the fields of aviation, high-speed rail, high-speed maglev trains and the like.
Drawings
FIG. 1 is a process flow diagram of a method of heat treating a cast aluminum alloy casting according to the present invention;
FIG. 2 is a photograph of a metallographic structure of a cast aluminum alloy casting used in example one before heat treatment;
FIG. 3 is a photograph of a metallographic structure of a heat-treated cast aluminum alloy casting treated by a conventional heat treatment process as applied to a cast aluminum alloy casting used in example one;
FIG. 4 is a photograph of a metallographic structure of a casting of a heat-treated cast aluminum alloy obtained in accordance with one embodiment;
FIG. 5 is an enlarged view of FIG. 4 at 200 times magnification;
FIG. 6 is an enlarged view of FIG. 4 at 500 times magnification;
FIG. 7 is a photograph of a metallographic structure of a cast aluminum alloy casting used in example five before heat treatment;
FIG. 8 is a photograph of a metallographic structure of a heat-treated cast aluminum alloy casting obtained by treating a cast aluminum alloy casting used in example V with a conventional heat treatment process;
FIG. 9 is a photograph showing the metallographic structure of a casting of heat-treated cast aluminum alloy obtained in example five.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, a heat treatment method for casting an aluminum alloy casting according to the present invention includes the steps of:
1) placing a cast aluminum alloy casting to be treated at 525-535 ℃, and carrying out solid solution treatment for 1-2 h; heating to 535-545 ℃, carrying out vacuum degassing treatment for 6-8 h, and carrying out water cooling to obtain a first water quenching casting;
2) placing the first water quenched casting obtained in the step 1) at 200-210 ℃, and performing aging treatment for 3-4 hours to obtain an aged casting;
3) placing the aging casting obtained in the step 2) at 525-535 ℃ again, and carrying out solid solution treatment for 1-2 h; heating to 535-545 ℃, carrying out solution treatment for 6-8 h, and carrying out water cooling to obtain a second water quenching casting;
4) placing the secondary water-quenched casting obtained in the step 3) at-110 to-120 ℃ and carrying out cryogenic treatment for 1 to 2 hours; then, placing the mixture at 140-150 ℃ for aging treatment for 5-6 h; placing the mixture at-110 to-120 ℃ again, and carrying out cryogenic treatment for 1 to 2 hours; and then, placing the aluminum alloy casting at 140-150 ℃, carrying out aging treatment for 10-12 h, and carrying out air cooling to obtain the cast aluminum alloy casting.
Preferably, in the step 4), during air cooling, the air temperature is 10-40 ℃, and the air cooling is carried out to the room temperature.
Preferably, in the step 3), the temperature of water is 60-80 ℃ during water cooling, and the water cooling time is 100-160 s.
Preferably, in the step 3), a temperature programming mode is adopted in the temperature rising process, and the temperature rising speed is 4-6 ℃/min.
Preferably, in the step 3), the pressure in the furnace chamber is 10 during the vacuum degassing treatment-4～10-5Pa。
Preferably, in the step 1), the temperature of water is 60-80 ℃ during water cooling, and the water cooling time is 100-160 s.
Preferably, in the step 1), a temperature-programmed manner is adopted in the temperature-raising process, and the temperature-raising speed is 4-6 ℃/min.
A cast aluminum alloy casting of the present invention, which is treated according to the heat treatment method for a cast aluminum alloy casting described in any one of the above.
Preferably, the cast aluminum alloy casting comprises the following components in percentage by weight: 4.5 to 5.5 percent of Si, 0.3 to 0.4 percent of Mg, 0.05 to 0.20 percent of Sb, 0.08 to 0.13 percent of Ti, 0.006 to 0.06 percent of Zr, the total content of impurities is not more than 0.1 percent, and the balance is aluminum.
Further, the impurities comprise the following elements in percentage by weight: fe is less than or equal to 0.07 percent, Sn is less than or equal to 0.02 percent, and Pb is less than or equal to 0.01 percent.
A preparation method of a cast aluminum alloy casting comprises the following steps:
a) firstly, heating a smelting furnace to raise the temperature of the furnace to 300-400 ℃, and keeping the temperature for 10-15 min; then, adding a raw material containing an Al element, a raw material containing an Si element, a raw material containing an Sb element, a raw material containing a Ti element and a raw material containing a Zr element, continuously heating and melting, raising the temperature of the melting furnace to 800-830 ℃, preserving the heat for 20-30 min, and stirring for 5-10 min to obtain an aluminum alloy melt;
b) cooling, namely cooling the temperature of the smelting furnace to 700-710 ℃, adding a refining agent A, wherein the refining agent A is hexachloroethane, the addition amount of the refining agent A is 0.4-0.6% of the total weight of the aluminum alloy melt, and stirring for 5-10 min;
c) keeping the temperature of the smelting furnace at 700-710 ℃, adding a raw material containing Mg, stirring for 3-5 min, and adding a refining agent B, wherein the refining agent B comprises the following components in percentage by weight: 50-55% of hexachloroethane, 18-20% of aluminum oxide, 18-20% of titanium trioxide, 4-5% of zirconium dioxide and 4-5% of calcium oxide, wherein the addition amount of the refining agent B is 0.1-0.2% of the total weight of the aluminum alloy melt, stirring for 5-10 min, standing for 20-30 min, and pouring to obtain the cast aluminum alloy casting to be treated.
Preferably, in the step 1), the raw material containing the Al element is pure aluminum metal; in the step 3), the raw material containing Mg element is pure magnesium metal.
Further, the purity of the pure aluminum metal is not less than 99.993%, and the purity of the pure magnesium metal is not less than 99.95%.
Preferably, in the step 1), the Si-containing material is a silicon alloy, the Sb-containing material is an antimony alloy, the Ti-containing material is a titanium alloy, and the Zr-containing material is a zirconium alloy.
Further, the silicon alloy is AlSi12, the antimony alloy is AlSb4, the titanium alloy is AlTi4, and the zirconium alloy is AlZr 4.
Example one
The invention discloses a heat treatment method for casting an aluminum alloy casting, which comprises the following steps:
1) placing a cast aluminum alloy casting to be treated at 525 ℃ and carrying out solution treatment for 1 h; heating to 535 deg.C at a temperature-raising speed of 4 deg.C/min by adopting programmed heating method, and controlling the ambient pressure in the furnace chamber to be 10-4Under Pa, carrying out vacuum degassing treatment for 8h, and carrying out water cooling at the temperature of 60 ℃ for 100s to obtain a first water quenching casting;
2) placing the first water quenched casting obtained in the step 1) at 200 ℃ for aging treatment for 3h to obtain an aged casting;
3) placing the aging casting obtained in the step 2) at 525 ℃ again, and carrying out solid solution treatment for 1 h; heating to 535 ℃ in a temperature-rise speed of 4 ℃/min by adopting a temperature-programming mode, carrying out solid solution treatment for 6h, and carrying out water cooling, wherein the temperature of water is 60 ℃ and the water cooling time is 100s, so as to obtain a secondary water-quenched casting;
4) placing the secondary water-quenched casting obtained in the step 3) at-110 ℃ and carrying out cryogenic treatment for 1 h; then, placing the mixture at 140 ℃ for aging treatment for 5 hours; placing at-110 deg.C again, and performing subzero treatment for 1 hr; and then, placing the aluminum alloy casting at 140 ℃, carrying out aging treatment for 10 hours, and carrying out air cooling to room temperature to obtain the cast aluminum alloy casting.
Example two
The invention discloses a heat treatment method for casting an aluminum alloy casting, which comprises the following steps:
1) taking a cast aluminum alloy casting to be treated, wherein the cast aluminum alloy casting to be treated comprises the following components in percentage by weight: 4.5-5.5% of Si, 0.3-0.4% of Mg, 0.05-0.20% of Sb, 0.08-0.13% of Ti, 0.006-0.06% of Zr, the total content of impurities is not more than 0.1%, and the balance of aluminum;
2) placing the cast aluminum alloy casting obtained in the step 1) at 535 ℃ and carrying out solution treatment for 2 h; heating to 545 deg.C at a temperature rising rate of 6 deg.C/min by programmed heating method, and keeping the ambient pressure in the furnace chamber at 10 deg.C-5Carrying out vacuum degassing treatment for 6 hours under Pa, and carrying out water cooling at the water temperature of 80 ℃ for 15min to obtain a first water quenching casting;
3) placing the first water quenched casting obtained in the step 2) at 210 ℃ for aging treatment for 4h to obtain an aged casting;
4) placing the aging casting obtained in the step 3) at 535 ℃ again, and carrying out solid solution treatment for 2 h; heating to 545 ℃ at a heating rate of 6 ℃/min by adopting a temperature programming mode, carrying out solution treatment for 8h, and carrying out water cooling, wherein the temperature of water is 80 ℃ and the water cooling time is 150s, so as to obtain a secondary water-quenched casting;
5) placing the secondary water quenching casting obtained in the step 4) at-105 ℃ and carrying out cryogenic treatment for 2 h; then, placing the mixture at 150 ℃ for aging treatment for 6 h; placing at-105 deg.C again, and performing subzero treatment for 2 hr; and then, placing the aluminum alloy casting at 150 ℃, carrying out aging treatment for 12h, and carrying out air cooling to room temperature to obtain the cast aluminum alloy casting.
EXAMPLE III
The invention discloses a heat treatment method for casting an aluminum alloy casting, which comprises the following steps:
s1 preparation of cast aluminum alloy casting to be treated
a) Weighing 4.5% of Si, 0.3% of Mg, 0.05% of Sb, 0.08% of Ti, 0.006% of Zr, less than or equal to 0.1% of impurities and the balance of Al according to the following weight percentage content of the obtained cast aluminum alloy casting;
wherein, Al and Mg adopt pure metals, the pure metal aluminum is Al99.993, and the element content requirement meets the GB/T8644-2000 requirement; the pure metal magnesium is Mg99.95, and the element content requirement meets the requirement of GB/T3499-; si adopts AlSi12 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement; sb adopts AlSb4 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement; ti adopts AlTi4 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement; zr adopts AlZr4 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement;
b) firstly, heating a smelting furnace to raise the temperature of the furnace to 300 ℃, and preserving the temperature for 10 min; then, adding pure metal Al, AlSi12 intermediate alloy, AlSb4 intermediate alloy, AlTi4 intermediate alloy and AlZr4 intermediate alloy, continuously heating and melting, raising the temperature of the melting furnace to 800 ℃, preserving the heat for 20min, and stirring for 5min to obtain an aluminum alloy melt;
c) cooling to reduce the temperature of the smelting furnace to 700 ℃, adding a refining agent A, wherein the refining agent A is hexachloroethane, the addition amount of the refining agent A is 0.4 percent of the total weight of the aluminum alloy melt, and stirring for 5 min;
c) keeping the temperature of the smelting furnace at 700 ℃, adding pure metal Mg, stirring for 3min, and adding a refining agent B, wherein the refining agent B comprises the following components in percentage by weight: 50% of hexachloroethane, 20% of aluminum oxide, 20% of titanium trioxide, 5% of zirconium dioxide and 5% of calcium oxide, wherein the addition amount of the refining agent B is 0.1% of the total weight of the aluminum alloy melt, stirring for 5min, standing for 20min, and pouring to obtain a cast aluminum alloy casting to be treated;
s2 Heat treatment of cast aluminum alloy castings
1) Placing the cast aluminum alloy casting to be treated obtained in the step S1 at 530 ℃ for solution treatment for 1.5 h; heating to 540 ℃ in a temperature-programmed manner at a heating rate of 5 ℃/min, and keeping the ambient pressure in the furnace chamber at 10 DEG C-4Carrying out vacuum degassing treatment for 7 hours under Pa, and carrying out water cooling, wherein the temperature of water is 70 ℃, and the water cooling time is 120s, so as to obtain a first water quenching casting;
2) placing the first water quenched casting obtained in the step 1) at 205 ℃, and carrying out aging treatment for 3.5h to obtain an aged casting;
3) putting the aging casting obtained in the step 2) at 530 ℃ again, and carrying out solution treatment for 1.5 h; heating to 540 ℃ in a temperature rise speed of 5 ℃/min in a temperature programming manner, carrying out solid solution treatment for 7h, and carrying out water cooling, wherein the temperature of water is 70 ℃, and the water cooling time is 120s, so as to obtain a second water-quenched casting;
4) placing the secondary water-quenched casting obtained in the step 3) at-110 ℃ and carrying out cryogenic treatment for 1.5 h; then, placing the mixture at 145 ℃ for aging treatment for 5.5 h; placing at-110 deg.C again, and performing subzero treatment for 1.5 hr; and then, placing the aluminum alloy casting at 145 ℃, carrying out aging treatment for 11h, and carrying out air cooling to room temperature to obtain the cast aluminum alloy casting.
Example four
The invention discloses a heat treatment method for casting an aluminum alloy casting, which comprises the following steps:
s1 preparation of cast aluminum alloy casting to be treated
a) Weighing the raw materials according to the following weight percentage of elements contained in the obtained cast aluminum alloy casting, wherein the raw materials comprise 5.5% of Si, 0.4% of Mg, 0.20% of Sb, 0.13% of Ti, 0.06% of Zr, less than or equal to 0.1% of impurities and the balance of Al;
wherein, Al and Mg adopt pure metals, the pure metal aluminum is Al99.993, and the element content requirement meets the GB/T8644-2000 requirement; the pure metal magnesium is Mg99.95, and the element content requirement meets the requirement of GB/T3499-; si adopts AlSi12 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement; sb adopts AlSb4 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement; ti adopts AlTi4 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement; zr adopts AlZr4 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement;
b) firstly, heating a smelting furnace to raise the temperature of the furnace to 400 ℃, and keeping the temperature for 15 min; then, adding pure metal Al, AlSi12 intermediate alloy, AlSb4 intermediate alloy, AlTi4 intermediate alloy and AlZr4 intermediate alloy, continuously heating and melting, raising the temperature of the melting furnace to 830 ℃, keeping the temperature for 30min, and stirring for 10min to obtain an aluminum alloy melt;
c) cooling to reduce the temperature of the smelting furnace to 710 ℃, adding a refining agent A, wherein the refining agent A is hexachloroethane, the addition amount of the refining agent A is 0.6 percent of the total weight of the aluminum alloy melt, and stirring for 10 min;
c) keeping the temperature of the smelting furnace at 710 ℃, adding pure metal Mg, stirring for 5min, and adding a refining agent B, wherein the refining agent B comprises the following components in percentage by weight: 55% of hexachloroethane, 18% of aluminum oxide, 18% of titanium trioxide, 4% of zirconium dioxide and 5% of calcium oxide, wherein the addition amount of the refining agent B is 0.2% of the total weight of the aluminum alloy melt, stirring for 10min, standing for 30min, and pouring to obtain a cast aluminum alloy casting to be treated;
s2 Heat treatment of cast aluminum alloy castings
1) Placing the cast aluminum alloy casting to be treated obtained in the step S1 at 530 ℃ for solution treatment for 1.5 h; heating to 540 ℃ in a temperature-programmed manner at a heating rate of 5 ℃/min, and keeping the ambient pressure in the furnace chamber at 10 DEG C-5Carrying out vacuum degassing treatment for 7 hours under Pa, and carrying out water cooling at the temperature of 70 ℃ for 13min to obtain a first water quenching casting;
2) placing the first water quenched casting obtained in the step 1) at 205 ℃, and carrying out aging treatment for 3.5h to obtain an aged casting;
3) putting the aging casting obtained in the step 2) at 530 ℃ again, and carrying out solution treatment for 1.5 h; heating to 540 ℃ in a temperature rise speed of 5 ℃/min by adopting a temperature programming mode, carrying out solid solution treatment for 7h, and carrying out water cooling, wherein the temperature of water is 70 ℃, and the water cooling time is 13min, so as to obtain a second water-quenched casting;
4) placing the secondary water-quenched casting obtained in the step 3) at-110 ℃ and carrying out cryogenic treatment for 1.5 h; then, placing the mixture at 145 ℃ for aging treatment for 5.5 h; placing at-110 deg.C again, and performing subzero treatment for 1.5 hr; and then, placing the aluminum alloy casting at 145 ℃, carrying out aging treatment for 11h, and carrying out air cooling to room temperature to obtain the cast aluminum alloy casting.
EXAMPLE five
The invention discloses a heat treatment method for casting an aluminum alloy casting, which comprises the following steps:
s1 preparation of cast aluminum alloy casting to be treated
a) Weighing the raw materials according to the following weight percentage of elements contained in the obtained cast aluminum alloy casting, wherein the raw materials comprise 5.00 percent of Si, 0.35 percent of Mg, 0.12 percent of Sb, 0.10 percent of Ti, 0.04 percent of Zr, less than or equal to 0.1 percent of impurities and the balance of Al;
wherein, Al and Mg adopt pure metals, the pure metal aluminum is Al99.993, and the element content requirement meets the GB/T8644-2000 requirement; the pure metal magnesium is Mg99.95, and the element content requirement meets the requirement of GB/T3499-; si adopts AlSi12 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement; sb adopts AlSb4 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement; ti adopts AlTi4 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement; zr adopts AlZr4 intermediate alloy, and the element content requirement meets the GB/T27677-2011 requirement;
b) firstly, heating a smelting furnace to raise the temperature of the furnace to 350 ℃, and keeping the temperature for 12 min; then, adding pure metal Al, AlSi12 intermediate alloy, AlSb4 intermediate alloy, AlTi4 intermediate alloy and AlZr4 intermediate alloy, continuously heating and melting, raising the temperature of the melting furnace to 815 ℃, keeping the temperature for 25min, and stirring for 8min to obtain an aluminum alloy melt;
c) cooling to 705 ℃, adding a refining agent A, wherein the refining agent A is hexachloroethane, the addition amount of the refining agent A is 0.5 percent of the total weight of the aluminum alloy melt, and stirring for 8 min;
c) keeping the temperature of the smelting furnace at 705 ℃, adding pure metal Mg, stirring for 4min, and adding a refining agent B, wherein the refining agent B comprises the following components in percentage by weight: 53 percent of hexachloroethane, 19 percent of aluminum oxide, 19 percent of titanium trioxide, 5 percent of zirconium dioxide and 4 percent of calcium oxide, wherein the addition amount of the refining agent B is 0.15 percent of the total weight of the aluminum alloy melt, the mixture is stirred for 8min, kept stand for 25min and poured to obtain a cast aluminum alloy casting to be treated;
s2 Heat treatment of cast aluminum alloy castings
1) Placing the cast aluminum alloy casting to be treated obtained in the step S1 at 530 ℃ for solution treatment for 1.5 h; heating to 540 ℃ in a temperature-programmed manner at a heating rate of 5 ℃/min, and keeping the ambient pressure in the furnace chamber at 10 DEG C-4Carrying out vacuum degassing treatment for 7 hours under Pa, and carrying out water cooling at the temperature of 70 ℃ for 11min to obtain a first water quenching casting;
2) placing the first water quenched casting obtained in the step 1) at 205 ℃, and carrying out aging treatment for 3.5h to obtain an aged casting;
3) putting the aging casting obtained in the step 2) at 530 ℃ again, and carrying out solution treatment for 1.5 h; heating to 540 ℃ in a temperature rising speed of 5 ℃/min by adopting a temperature programming mode, carrying out solid solution treatment for 7h, and carrying out water cooling, wherein the temperature of water is 70 ℃, and the water cooling time is 11min, so as to obtain a second water-quenched casting;
4) placing the secondary water-quenched casting obtained in the step 3) at-110 ℃ and carrying out cryogenic treatment for 1.5 h; then, placing the mixture at 145 ℃ for aging treatment for 5.5 h; placing at-110 deg.C again, and performing subzero treatment for 1.5 hr; and then, placing the aluminum alloy casting at 145 ℃, carrying out aging treatment for 11h, and carrying out air cooling to room temperature to obtain the cast aluminum alloy casting.
Respectively measuring the metallographic structures of the cast aluminum alloy casting to be treated in the first embodiment of the invention, the cast aluminum alloy casting treated by the heat treatment method in the first embodiment of the invention, the cast aluminum alloy casting to be treated in the fifth embodiment of the invention and the cast aluminum alloy casting treated by the heat treatment method in the fifth embodiment of the invention; the cast aluminum alloy casting to be treated used in the first embodiment of the invention and the cast aluminum alloy casting to be treated used in the fifth embodiment of the invention are respectively treated according to the heat treatment process specified in the GB/T1173-2013 standard to obtain a comparison sample, and then the metallographic structure of the comparison sample is measured according to the method.
As can be seen from the attached figure 2, fine spherical eutectic silicon structures are uniformly distributed in the metallographic structure of the obtained as-cast aluminum alloy, which is benefited by the effective modification effect of Sb and Ti elements; it can also be seen that there are distinct holes in the metallographic structure, see the circled portion in fig. 2, with a hole size of about 50 μm. As can be seen from FIG. 3, the holes of the cast aluminum alloy castings treated by the heat treatment process specified in GB/T1173-2013 standard are still existed, which is shown in the circular frame part in FIG. 3. As can be seen from the attached drawings 4, 5 and 6, the cast aluminum alloy casting treated by the heat treatment process of the invention has no obvious holes in the metallographic structure, which shows that the internal structure of the casting is compact in the vacuum degassing and cryogenic treatment processes; in addition, as can be seen from FIG. 4, the crystal grains of the cast aluminum alloy casting treated by the heat treatment process of the present inventionThe size has no obvious change, which shows that the nano-scale Al in the alloy of the invention3Ti and Al3Zr or Al3The (Ti, Zr) precipitates have a pinning effect with respect to the grain boundary.
As can be seen from fig. 7, 8 and 9, the cast aluminum alloy casting to be treated in the fifth embodiment of the present invention, the cast aluminum alloy casting treated by the heat treatment method in the fifth embodiment, and the control sample treated by the heat treatment process specified in the GB/T1173-2013 standard show the same rule, that is, the cast aluminum alloy casting treated by the heat treatment process of the present invention has no obvious holes in the metallographic structure and no obvious change in the grain size, as shown in fig. 9; however, the holes of the control are still present, see the circled portions in fig. 7 and 8, respectively. The results show that the heat treatment method of the invention has stable treatment effect on the cast aluminum alloy castings and reliable treatment results.
Cutting off partial samples from the five heat-treated cast aluminum alloy castings obtained in the first to fifth examples and the cast aluminum alloy castings to be treated before the heat treatment of the five cast aluminum alloy castings, and measuring the tensile strength and the elongation according to the measuring method of GB/T228-2010 for the tensile strength and the elongation of the alloy; and the cast aluminum alloy castings to be treated before the heat treatment are respectively treated by the existing heat treatment process to obtain five reference samples, the reference samples are also used for measuring the tensile strength and the elongation of the alloy according to the measuring method of GB/T228-.
TABLE 1 mechanical Properties of cast aluminum alloys
As can be seen from Table 1, the tensile strength of the cast aluminum alloy castings treated by the heat treatment method is 319-332MPa, which is obviously higher than the tensile strength before heat treatment and is also obviously higher than the tensile strength of the comparison sample; the elongation of the cast aluminum alloy casting treated by the heat treatment method is between 13.6 and 16.1 percent and is obviously higher than that of a control sample; therefore, the cast aluminum alloy casting treated by the heat treatment method has better tensile strength and elongation, both the tensile strength and the elongation exceed the mechanical properties of ZL101A specified in GB/T1173-2013 (ZL 101A-T6 in GB/T1173-2013 requires that the tensile strength is more than or equal to 295 and the elongation is more than or equal to 3%); therefore, the mechanical property of the cast aluminum alloy casting treated by the heat treatment method exceeds the index specified by the technical requirement, the quality consistency of the casting is good, and the production efficiency is increased.
Carrying out fatigue performance test experiments on five parts of the heat-treated cast aluminum alloy castings obtained in the first to fifth embodiments, the to-be-treated cast aluminum alloy castings of the five parts of the cast aluminum alloy castings before the heat treatment, and five parts of control samples obtained after the to-be-treated cast aluminum alloy castings before the heat treatment are respectively treated by the heat treatment process specified in the GB/T1173-2013 standard; the fatigue test conditions were: sigmamax100MPa, R-1, frequency 120 Hz; the results are shown in Table 2.
TABLE 2 fatigue Performance test results for cast aluminum alloys
| Sample name | After heat treatment (second time) | Control sample (second) |
| Example one | 3.0×107 | 4.2×105 |
| Example two | 2.8×107 | 6.1×105 |
| EXAMPLE III | 1.6×107 | 1.0×106 |
| Example four | 2.0×107 | 1.5×105 |
| EXAMPLE five | 2.9×107 | 3.3×105 |
As can be seen from Table 2, the tensile high frequency fatigue properties of the cast aluminum alloy castings treated by the heat treatment method of the present invention are 1.6X 107-3.0×107This is significantly higher than the tensile high frequency fatigue properties of the control.
Therefore, compared with the prior art, the invention has the beneficial effects that: during vacuum degassing treatment, hydrogen atoms dissolved in the casting matrix diffuse to the surface of the casting to form hydrogen gas which is pumped away, and vacancies are formed in crystal lattices, so that the obvious dehydrogenation effect is achieved, the content of hydrogen in the casting is reduced, the fatigue performance of the casting is improved, and the reliability of the casting is improved; high-temperature solid solution, high-temperature aging, cryogenic treatment and low-temperature aging are organically combined, and a precipitated phase is rapidly, fully and uniformly precipitated during high-temperature aging; when solid solution is carried out at high temperature, the precipitated phase is fully dissolved back to the matrix again, and solute atoms dissolved back to the matrix are distributed more uniformly, so that subsequent aging precipitation is facilitated; the cold and hot temperature are alternately treated, the tensile stress and the compressive stress are generated in the casting, so that the casting is subjected to uniform micro deformation, the internal stress of the casting is eliminated, and meanwhile, the micro deformation promotes dislocation to be generated in the casting and used as a nucleation position of a precipitated phase, so that a large amount of precipitated phases are promoted to be precipitated; meanwhile, due to the alternate treatment of cold and hot temperatures, micro defects can be compacted, the density of the casting is improved, and the fatigue performance of the casting is further improved; the low-temperature aging treatment can obviously improve the precipitation power of solute atoms, and the volume fraction of a precipitated phase is gradually increased in the aging process, so that the formed strengthening phase has smaller size, more dispersive distribution, better strengthening effect and better comprehensive mechanical property. The cast aluminum alloy casting obtained by the invention meets the performance requirements of the fields of aviation, high-speed rail and high-speed maglev trains on the cast aluminum alloy casting, expands the application range of the cast aluminum alloy casting, and can be widely applied to the fields of aviation, high-speed rail, high-speed maglev trains and the like.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A heat treatment method for casting an aluminum alloy casting, characterized by comprising the steps of:
1) placing a cast aluminum alloy casting to be treated at 525-535 ℃, and carrying out solid solution treatment for 1-2 h; heating to 535-545 ℃, carrying out vacuum degassing treatment for 6-8 h, and carrying out water cooling to obtain a first water quenching casting;
2) placing the first water quenched casting obtained in the step 1) at 200-210 ℃, and performing aging treatment for 3-4 hours to obtain an aged casting;
3) placing the aging casting obtained in the step 2) at 525-535 ℃ again, and carrying out solid solution treatment for 1-2 h; heating to 535-545 ℃, carrying out solution treatment for 6-8 h, and carrying out water cooling to obtain a second water quenching casting;
4) placing the secondary water-quenched casting obtained in the step 3) at-110 to-120 ℃ and carrying out cryogenic treatment for 1 to 2 hours; then, placing the mixture at 140-150 ℃ for aging treatment for 5-6 h; placing the mixture at-110 to-120 ℃ again, and carrying out cryogenic treatment for 1 to 2 hours; and then, placing the aluminum alloy casting at 140-150 ℃, carrying out aging treatment for 10-12 h, and carrying out air cooling to obtain the cast aluminum alloy casting.
2. A heat treatment method for casting aluminum alloy castings according to claim 1, characterized in that:
and in the step 4), air cooling is carried out at the air temperature of 10-40 ℃ to room temperature.
3. A heat treatment method for casting aluminum alloy castings according to claim 1, characterized in that:
in the step 3), during water cooling, the temperature of water is 60-80 ℃, and the water cooling time is 100-160 s;
preferably, in the step 3), a temperature programming mode is adopted in the temperature rising process, and the temperature rising speed is 4-6 ℃/min.
4. A heat treatment method for casting aluminum alloy castings according to claim 1, characterized in that:
in the step 1), the pressure of the furnace chamber environment is 10 during vacuum degassing treatment-4～10-5Pa；
Preferably, in the step 1), during water cooling, the temperature of water is 60-80 ℃, and the water cooling time is 100-160 s;
preferably, in the step 1), a temperature-programmed manner is adopted in the temperature-raising process, and the temperature-raising speed is 4-6 ℃/min.
5. A cast aluminum alloy casting characterized by: the cast aluminum alloy casting treated by the heat treatment method for a cast aluminum alloy casting according to any one of claims 1 to 4.
6. The cast aluminum alloy casting of claim 5, comprising the following composition in weight percent:
4.5 to 5.5 percent of Si, 0.3 to 0.4 percent of Mg, 0.05 to 0.20 percent of Sb, 0.08 to 0.13 percent of Ti, 0.006 to 0.06 percent of Zr, the total content of impurities is not more than 0.1 percent, and the balance is aluminum.
7. A cast aluminum alloy casting according to claim 6, wherein the impurities comprise the following elements in weight percent:
Fe≤0.07％，Sn≤0.02％，Pb≤0.01％。
8. a method of making a cast aluminum alloy casting according to claim 6, comprising the steps of:
a) firstly, heating a smelting furnace to raise the temperature of the furnace to 300-400 ℃, and keeping the temperature for 10-15 min; then, adding a raw material containing an Al element, a raw material containing an Si element, a raw material containing an Sb element, a raw material containing a Ti element and a raw material containing a Zr element, continuously heating and melting, raising the temperature of the melting furnace to 800-830 ℃, preserving the heat for 20-30 min, and stirring for 5-10 min to obtain an aluminum alloy melt;
b) cooling, namely cooling the temperature of the smelting furnace to 700-710 ℃, adding a refining agent A, wherein the refining agent A is hexachloroethane, the addition amount of the refining agent A is 0.4-0.6% of the total weight of the aluminum alloy melt, and stirring for 5-10 min;
c) keeping the temperature of the smelting furnace at 700-710 ℃, adding a raw material containing Mg, stirring for 3-5 min, and adding a refining agent B, wherein the refining agent B comprises the following components in percentage by weight: 50-55% of hexachloroethane, 18-20% of aluminum oxide, 18-20% of titanium trioxide, 4-5% of zirconium dioxide and 4-5% of calcium oxide, wherein the addition amount of the refining agent B is 0.1-0.2% of the total weight of the aluminum alloy melt, stirring for 5-10 min, standing for 20-30 min, and pouring to obtain the cast aluminum alloy casting to be treated.
9. The method of producing a cast aluminum alloy according to claim 8, characterized in that:
in the step 1), the raw material containing Al element is pure aluminum metal; in the step 3), the raw material containing Mg element is pure magnesium metal;
preferably, the purity of the pure aluminum metal is not less than 99.993%, and the purity of the pure magnesium metal is not less than 99.95%.
10. The method of producing a cast aluminum alloy according to claim 8, characterized in that:
in the step 1), the raw material containing Si element is silicon alloy, the raw material containing Sb element is antimony alloy, the raw material containing Ti element is titanium alloy, and the raw material containing Zr element is zirconium alloy;
preferably, the silicon alloy is AlSi12, the antimony alloy is AlSb4, the titanium alloy is AlTi4, and the zirconium alloy is AlZr 4.
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