Corrosion-resistant aluminum alloy ingot and method of making

Abstract

The application relates to the technical field of aluminum alloy ingot preparation, and discloses a corrosion-resistant aluminum alloy ingot and a preparation method thereof; first, initial raw materials are weighed according to mass proportions, intermediate alloys are pre-synthesized, and a pre-alloyed melt is prepared by adopting an inert gas gradient melting method; second, a refining agent is prepared, mixed gas is synchronously introduced for rotary injection refining, ultrasonic-plasma coupling treatment is carried out to remove impurities, and a deeply purified melt is obtained; a multi-stage filtering device is further constructed to carry out vacuum membrane separation and impurity removal, and an ultrahigh-purity melt is obtained; finally, the ultrahigh-purity melt is subjected to micro-pressure casting, a pulse magnetic field is set to dynamically control magnetic field parameters, multi-stage heat treatment strengthening is carried out, a whale optimization algorithm is introduced to optimize the magnetic field parameters, and the corrosion-resistant aluminum alloy ingot is formed; the application realizes the purpose of preparing the corrosion-resistant aluminum alloy ingot through gradient melting, cooperative refining, filtering separation and ingot solidification.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy ingot preparation, in particular to a corrosion-resistant aluminum alloy ingot and a preparation method thereof. BACKGROUND

[0002] The corrosion-resistant aluminum alloy ingot refers to an aluminum alloy base material endowed with excellent environmental medium corrosion resistance through specific alloy component proportioning and process control. Such an ingot blank is the basis for manufacturing key corrosion-resistant components such as ships, offshore platforms, chemical containers, automobile parts, aerospace structural parts, etc. through subsequent processing (such as extrusion, rolling, forging). At present, with the development of high-end equipment manufacturing industry and the increasingly harsh service environment, higher requirements are put forward for the corrosion resistance of aluminum alloy materials. Although the existing alloys on the market have certain corrosion resistance, higher comprehensive performance (such as high corrosion resistance, high strength, and good formability) of aluminum alloy ingot materials, as well as stable, efficient, and low-cost production of such ingot materials, are still the goals and challenges pursued in the material field. The existing technology still has room for improvement in terms of product performance uniformity, long-term stability in extreme environments, and cost control.

[0003] The traditional preparation method of corrosion-resistant aluminum alloy ingot first performs raw material pretreatment, performs necessary cleaning and drying on the raw material or intermediate alloy, adds the main raw material into a melting furnace to heat and melt to form an aluminum melt, adds alloying elements or intermediate alloys required for alloying into the melt, removes hydrogen and non-metallic inclusions, performs grain refinement, and finally pours into a metal mold to cool and solidify to form an aluminum alloy ingot blank.

[0004] The traditional preparation method of corrosion-resistant aluminum alloy ingot mainly relies on manual feeding and melt forced stirring convection during the alloying process, and the temperature control and other processes of each step are greatly affected by human factors, which has the risk of high burning loss and uneven element distribution, which may increase the impurity content and increase the micro defects of the final ingot blank, affecting the final corrosion resistance. SUMMARY

[0005] In view of the problems in the related art, the present application provides a corrosion-resistant aluminum alloy ingot and a preparation method thereof to overcome the technical problems existing in the prior art.

[0006] To solve the technical problems, the present application is realized by the following technical scheme:

[0007] The present application is a preparation method of a corrosion-resistant aluminum alloy ingot, comprising the following steps:

[0008] S1, gradient smelting: according to the mass ratio, the initial raw material is weighed, the intermediate alloy is pre-synthesized, the high-purity magnesium ingot is weighed, the inert gas gradient smelting method is used, the intermediate alloy and high-purity aluminum ingot are stepwise heated and smelted, and a pre-alloying melt is obtained;

[0009] S2, synergistic refining: preparing a refining agent, synchronously blowing mixed gas to the pre-alloying melt for rotary injection refining, and then removing impurities by ultrasonic-plasma coupling treatment to obtain a deeply purified melt;

[0010] S3, filtration and separation: constructing a multi-stage filtration device, vacuum membrane separation and impurity removal are performed on the deeply purified melt to obtain an ultrahigh-purity melt;

[0011] S4, ingot solidification: micro-pressure casting is performed on the ultrahigh-purity melt to obtain a shaped melt, a pulse magnetic field is set to dynamically control the magnetic field parameters, the shaped melt is solidified in the pulse magnetic field, and multi-stage heat treatment is performed to strengthen the magnetic field parameters, a whale optimization algorithm is introduced to optimize the magnetic field parameters, and a corrosion-resistant aluminum alloy ingot is formed.

[0012] Preferably, the pre-synthesized intermediate alloy comprises the following steps:

[0013] According to the mass ratio, 99.99wt% high-purity aluminum ingot and Sr foil with Sr content of 20±0.5wt% are weighed and placed in an argon gas protection induction furnace to prepare Al-Sr intermediate alloy;

[0014] According to the mass ratio, 5:1:0.2 of titanium sponge, KBF4 powder and Sc2O3 nano powder are weighed, and then combined with high-purity aluminum ingot to prepare Al-Ti-B-Sc intermediate alloy.

[0015] Preferably, the inert gas gradient smelting method comprises the following steps:

[0016] According to the mass ratio, high-purity magnesium ingot with more than 99.95wt% is placed in a vacuum induction smelting furnace, vacuum is extracted to 10 -2 Pa, and then pure argon gas with a purity of 99.999% is filled;

[0017] The stepwise heating smelting includes first stage, second stage, third stage and fourth stage, the temperature is kept at 700±5℃ in the first stage, Al-Mn and Al-Cr intermediate alloy are added, axial electromagnetic stirring is applied, and the process lasts for 15min, the temperature is kept at 750±5℃ in the second stage, Al-Hf intermediate alloy and Al-Zr intermediate alloy are added, electromagnetic stirring is applied synchronously, and the process lasts for 30min;

[0018] In the third stage, the temperature is kept at 680±5℃, Al-Sr intermediate alloy is added by burying, and high-purity magnesium ingot is put in, and in the fourth stage, the temperature is kept at 640±5℃, Al-Ti-B-Sc intermediate alloy is added, and the temperature is kept for 10 min, to obtain a pre-alloyed melt.

[0019] Preferably, the synchronous blowing of the mixed gas on the pre-alloyed melt includes the following steps:

[0020] According to the mass ratio, 45±5wt% of MgCl2, 30±2wt% of KCl, 20±2wt% of MgF2 and 5±0.5wt% of CeCl3 are weighed, mixed and pressed into particles to obtain a refining agent, which is then put into a rotary spraying device and continuously supplied with Ar and SF6 mixed gas, and the rotary spraying device is started to obtain a refined alloyed melt.

[0021] Preferably, the ultrasonic-plasma coupling treatment for removing impurities includes the following steps:

[0022] The refined alloyed melt is cooled to 670±5℃, a titanium alloy ultrasonic probe is inserted, and a non-transferred arc plasma beam is applied above the refined alloyed melt to obtain a deeply purified melt.

[0023] Preferably, the vacuum membrane separation and impurity removal of the deeply purified melt include the following steps:

[0024] An alumina ceramic filter tank and a yttrium-stabilized zirconia porous membrane separator are obtained, a multi-stage filtering device is constructed, the deeply purified melt is injected into the alumina ceramic filter tank, and gravity filtration is used to remove inclusions to obtain a filtered melt, and then the filtered melt flows through the yttrium-stabilized zirconia porous membrane separator to obtain an ultrahigh-purity melt.

[0025] Preferably, the multi-stage heat treatment strengthening includes the following steps:

[0026] A pressure crystallizer is configured, a boron nitride coating is sprayed on the inner wall of the pressure crystallizer, the ultrahigh-purity melt is cooled to 655±3℃, and the ultrahigh-purity melt is poured into the pressure crystallizer while a pressure is applied to perform micro-pressure casting to obtain a shaped melt.

[0027] A water-cooled copper coil is arranged in the pressure crystallizer to form a pulsed magnetic field, and the pulsed magnetic field is set to dynamically control the magnetic field parameters, and the peak magnetic field strength, pulse frequency and magnetic field direction are taken as the magnetic field parameters to determine the range of the magnetic field parameters.

[0028] The pulse magnetic field is started at the initial stage of solidification of the forming melt, high-pressure nitrogen gas is introduced to strengthen heat exchange, the pressure is released and the mold is opened when the temperature drops to 150 DEG C, and the primary aluminum alloy ingot is obtained; the primary aluminum alloy ingot is placed at a temperature of 120±2 DEG C for 10h, and then placed at a temperature of 170±2 DEG C for 8h, and the final aluminum alloy ingot is obtained after water cooling.

[0029] Preferably, the forming of the corrosion-resistant aluminum alloy ingot comprises the following steps:

[0030] The grain size, nano-phase size and corrosion resistance time of the final aluminum alloy ingot are detected, and a target function is established;

[0031] The target function is used as a fitness function, the whale optimization algorithm is improved, and a mutation whale optimization algorithm is obtained;

[0032] A whale population is randomly generated, the positions of the whale individuals are uniformly distributed in the magnetic field parameter range, the whale individuals in the whale population represent a group of magnetic field parameters, and the process of optimizing the positions of the whale individuals is regarded as the process of optimizing the magnetic field parameters;

[0033] The dynamic probability is calculated, and the whale population enters different mechanisms to update the positions of the whale individuals;

[0034] The cooperation evolution strategy is introduced, the position of the whale individual corresponding to the minimum fitness function value is selected, the next iteration is entered, the final whale population is obtained, the whale individual corresponding to the best fitness function value is searched, and the optimized magnetic field parameters are obtained;

[0035] According to the optimized magnetic field parameters, the pulse magnetic field is readjusted, the forming melt is solidified in the magnetic field, and multi-stage heat treatment strengthening is carried out, so that the corrosion-resistant aluminum alloy ingot is obtained.

[0036] The present application has the following beneficial effects:

[0037] 1. The present application uses the inert gas gradient melting method to perform stepwise temperature rising melting by pre-synthesizing intermediate alloy, reduces the high activity element burning loss rate and the problem of uneven chemical composition distribution in the process of gradient melting in the inert gas, improves the element utilization rate, avoids that the nano-phase size is too large, and obtains a pre-alloyed melt.

[0038] 2. The present application prepares a refining agent and introduces mixed gas to perform rotary injection refining, removes impurities by ultrasonic-plasma coupling treatment, cooperates to accelerate the migration of inclusions, breaks ≥5 mu inclusions by ultrasonic cavitation effect, ionizes Al2O3 / MgO nano-inclusions by a plasma beam, realizes efficient removal of nano-inclusions, makes the solute distribution segregation index lower than that of a traditional method, and avoids daily operation errors.

[0039] 3. The invention constructs a multi-stage filtering device for vacuum membrane separation and impurity removal, uses an alumina ceramic filter tank to realize molecular-level dehydrogenation, captures various ions, and realizes double-mechanism removal by combining vacuum volatilization, realizes multi-stage interception by gradient pore size design, and further reduces the density of inclusions.

[0040] 4. The invention uses micro-pressure casting, sets up a dynamic control of magnetic field parameters by a pulse magnetic field, uses the pulse magnetic field to generate a spiral Lorentz force, improves the efficiency of dendrite fragmentation, makes the corrosion propagation path tortuous, reduces the size of the nano-strengthening phase, uniformly distributes the nano-phase to effectively inhibit corrosion, and then performs multi-stage heat treatment strengthening, improves the whale optimization algorithm, overcomes the slow convergence speed of the traditional algorithm, balances the global search and local search capabilities, thereby improving the global search performance and convergence speed, locks the best magnetic field parameters, greatly reduces the process cycle and preparation energy consumption, and simultaneously comprehensively improves corrosion resistance and tensile strength.

[0041] Of course, implementing any product of the present invention does not necessarily require all the advantages described above to be achieved simultaneously. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, the drawings can also be obtained without creative labor.

[0043] Figure 1 A flowchart of a method for preparing a corrosion-resistant aluminum alloy ingot is provided. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0045] Embodiment 1

[0046] Further, in order to better introduce the technical solutions of the embodiments of the present application, as shown in the drawings, Figure 1 the embodiments of the present application provide a method for preparing a corrosion-resistant aluminum alloy ingot, which specifically includes the following contents:

[0047] S1, gradient melting: the initial raw materials are weighed according to the mass ratio, the intermediate alloy is pre-synthesized, the high-purity magnesium ingot is weighed, the inert gas gradient melting method is used, the intermediate alloy and high-purity aluminum ingot are stepwise heated and melted, and the pre-alloying melt is obtained;

[0048] The S1 comprises the following steps:

[0049] S11, according to the mass ratio, take 99.99wt% high-purity aluminum ingot and Sr content of 20±0.5wt% Sr foil, placed in the argon protection induction furnace, the temperature of the argon protection induction furnace is raised to 780±5℃ for smelting, the oxygen content of the ingot is controlled to be less than or equal to 100ppm, and the electromagnetic stirring is controlled for 10min, then the ingot is poured, and Al-Sr intermediate alloy is obtained;

[0050] According to the mass ratio of 5:1:0.2, the sponge titanium, KBF4 powder and Sc2O3 nano powder are weighed respectively, and then combined with the high-purity aluminum ingot, ignition reaction is carried out at a temperature of 950±10℃, and the reaction product is obtained. After the reaction product is treated by ball milling to a particle size of ≤200nm, an Al-Ti-B-Sc intermediate alloy is obtained.

[0051] According to the mass ratio, take more than 99.95wt% high-purity magnesium ingot, Al-Mn intermediate alloy with Mn content of 10±0.5wt%, Al-Cr intermediate alloy with Cr content of 5±0.2wt%, Al-Hf intermediate alloy with Hf content of 8±0.5wt%, and Al-Zr intermediate alloy with Zr content of 4±0.2wt%;

[0052] S12, according to the mass ratio, take more than 99.95wt% high-purity magnesium ingot, place it in a vacuum induction melting furnace, vacuumize to 10 -2 Pa, then fill in argon with a purity of 99.999%, use inert gas gradient smelting method, stepwise temperature rising smelting of intermediate alloy and high-purity aluminum ingot, get pre-alloying melt, the specific steps are as follows:

[0053] S121, set stepwise temperature rising smelting including first stage, second stage, third stage and fourth stage, keep temperature at 700±5℃ in first stage, add Al-Mn, Al-Cr intermediate alloy, apply axial electromagnetic stirring, last for 15min, enter second stage, keep temperature at 750±5℃, add Al-Hf, Al-Zr intermediate alloy, synchronous electromagnetic stirring is applied, and keep for 30min;

[0054] S122, keep temperature at 680±5℃ in third stage, add Al-Sr intermediate alloy by embedding, and put in high-purity magnesium ingot, enter fourth stage, keep temperature at 640±5℃, add Al-Ti-B-Sc intermediate alloy, keep for 10min, get pre-alloying melt;

[0055] In the embodiment, first, the initial raw material is weighed according to the mass ratio, the intermediate alloy is pre-synthesized, the inert gas gradient melting method is used for stepwise temperature rising melting, and the pre-alloyed melt is obtained; in the method, the intermediate alloy is synthesized by gradient melting in the inert gas, the problems of high active element burning loss rate and uneven chemical composition distribution are reduced, the element utilization rate is improved, and the size of the nano phase is avoided to be too large; specifically, for example, 5 kg of high-purity aluminum ingot (99.99%) + 1.25 kg of Sr foil (99.5%) is melted in an argon protection induction furnace at 780 DEG C, electromagnetic stirring is performed for 10 min, and the oxygen content of the ingot is detected by an inert gas analyzer to be 85 ppm; 4.2 kg of aluminum powder (99.9%), 0.84 kg of sponge titanium (Ti≥99.7%, preheated at 300 DEG C), 0.17 kg of KBF4 powder (200 mesh), and 0.034 kg of Sc2O3 nano powder (30 nm) are used to produce the intermediate alloy; gradient melting: first stage (basic melting), 700±5 DEG C, Al-Mn alloy (Mn: 1.2wt%) is added, second stage (Hf / Zr addition), 750±3 DEG C, Al-Hf (Hf: 5wt%) and Al-Zr (Zr: 4wt%) are added, third stage (Mg / Sr addition), 680±2 DEG C, Al-Sr intermediate alloy + Mg ingot (pure iron foil wrapped) are added, fourth stage (TiB2 addition), 640±3 DEG C, Al-Ti-B-Sc intermediate alloy is added; at this time, the Sr burning loss rate is 2.7%, the composition distribution uniformity deviation obtained by electron probe surface scanning is ≤2wt%, and Sr forms a dense SrAl2O4 oxide film at the grain boundary, which is the basis for building a corrosion-resistant phase;

[0056] S2, synergistic refining: preparing a refining agent, synchronously blowing mixed gas to the pre-alloyed melt for rotary spraying refining, and then removing impurities by ultrasonic-plasma coupling treatment to obtain a deeply purified melt;

[0057] The S2 includes the following steps:

[0058] S21, 45±5wt% of MgCl2, 30±2wt% of KCl, 20±2wt% of MgF2 and 5±0.5wt% of CeCl3 are weighed according to the mass ratio, mixed and pressed into particles to obtain a refining agent; 1.5 kg of the refining agent is put into a rotary spraying device for 1 t of the pre-alloyed melt, Ar and SF6 mixed gas are continuously blown at a gas flow rate of 15 L / min, the rotary spraying device is started and rotated at a speed of 500±20 rpm, the spraying time is 25 min, and the refined alloyed melt is obtained.

[0059] S22, cooling the refined alloying melt to 670±5℃, inserting a titanium alloy ultrasonic probe, maintaining a frequency of 40 kHz, and lasting for 20 min; applying a non-transferred arc plasma beam with a current intensity of 80±5 A and a voltage of 150 V above the refined alloying melt to remove impurities and obtain a deeply purified melt;

[0060] In the embodiment, a refining agent is prepared, mixed gas is synchronously introduced for rotary injection refining, and then ultrasonic-plasma coupling treatment is performed to remove impurities, thereby obtaining a deeply purified melt; the method uses rotary injection refining and ultrasonic-plasma coupling to accelerate the migration of inclusions, the ultrasonic cavitation effect breaks ≥5 μm inclusions, the plasma beam ionizes Al2O3 / MgO nano inclusions, thereby realizing efficient removal of nano inclusions, and the solute distribution segregation index is lower than that of the traditional method, while avoiding daily operation errors; specifically, for example, a rotary injection machine is provided, a 40 kHz titanium alloy ultrasonic probe and a non-transferred arc plasma generator are used, the refining agent dosage is 1.5 kg / t, the mixed gas is Ar+0.5% SF6 (total flow rate 15 L / min), the rotor speed is 500 rpm, the treatment time is 25 min, the initial slag phase composition is mainly Al2O3 / MgO, and the slag phase composition at the end of injection is Ce2O3 / Al2O3, which accounts for >60%; the melt is cooled to 670±3℃, the ultrasonic probe is inserted, the immersion depth is 150 mm, ultrasonic treatment (40 kHz) is performed only in 0-10 min, and ultrasonic+plasma synchronous operation is performed in 10-20 min; during the whole process, scanning electron microscopy (SEM) particle size statistics shows that the inclusion density decreases from the initial value of 8.7×10 5 4 cm³ to 3.2×10 4 cm³ (a decrease of 96.3%), and the maximum inclusion size decreases from the initial value of 12.5 μm to 0.38 μm (a decrease of 97.0%);

[0061] S3, filtration separation: constructing a multi-stage filtration device, performing vacuum membrane separation and impurity removal on the deeply purified melt, and obtaining an ultrahigh-purity melt;

[0062] The S3 includes the following steps:

[0063] S31, obtaining an alumina ceramic filter tank with a pore size of 10±0.5 μm, obtaining a yttrium-stabilized zirconia porous membrane separator with a pore size of 0.1±0.02 μm, constructing a multi-stage filtration device, injecting the deeply purified melt into the alumina ceramic filter tank, and filtering inclusions by gravity to obtain a filtered melt;

[0064] S32, flowing the filtered melt through the yttrium-stabilized zirconia porous membrane separator at a flow rate of 1.5±0.2 kg / min, and maintaining a vacuum degree of 10 -3Pa, melt temperature 660±5℃, film surface temperature difference 50±1℃, processing time of melt per ton 12 min, to obtain ultra-high purity melt;

[0065] In this embodiment, a multi-stage filtering device is constructed to perform vacuum membrane separation and impurity removal on the deeply purified melt to obtain an ultra-high purity melt; the method uses an alumina ceramic filter tank to achieve molecular-level dehydrogenation and capture various ions, and combines vacuum evaporation to achieve double-mechanism removal, and gradient-pore-size design to achieve multi-stage interception, so that the inclusion density is further reduced; specifically, for example, the deeply purified melt has a temperature of 665℃ and a weight of 800 kg, the alumina ceramic tank has a pore size of 10 μm and an area of 0.5 m², and the yttrium-stabilized zirconia porous membrane separator has a pore size of 0.1 μm and a CeO2 coating thickness of 200 nm; primary filtration, melt flow rate: 12 kg / min, filtration time: 67 min; vacuum membrane separation, real-time monitoring data mean, to obtain a vacuum degree of 9.8×10 -4 Pa, melt temperature 661.2℃, film surface temperature 608.5℃, melt flow rate 1.48 kg / min, transmembrane pressure difference 0.27 MPa; at the inlet end, the hydrogen content (ml / 100 g Al) is 0.31 measured by a hydrogen analyzer, the Na residue (ppm) is 7.5 and the K residue (ppm) is 2.1 analyzed by inductively coupled plasma mass spectrometry, and the inclusion density is 3.2×10 4 cm³; at the outlet end, the hydrogen content (ml / 100 g Al) is 0.036 (decreased by 88.4%), the Na residue (ppm) is 0.28 (decreased by 96.3%), the K residue (ppm) is 0.09 (decreased by 95.7%), and the inclusion density is 8.2×10 3 cm³ (decreased by 74.3%);

[0066] S4, ingot solidification: micro-pressure casting is performed on the ultra-high purity melt to obtain a shaped melt, a pulse magnetic field is set to dynamically control magnetic field parameters, the shaped melt is solidified in the pulse magnetic field, and multi-stage heat treatment strengthening is performed, a whale optimization algorithm is introduced to optimize the magnetic field parameters, and a corrosion-resistant aluminum alloy ingot is formed;

[0067] The S4 includes the following steps:

[0068] S41, configuring a pressure crystallizer, spraying a boron nitride coating with a thickness of 50 μm on the inner wall of the pressure crystallizer, cooling the ultra-high purity melt to 655±3℃, pouring the ultra-high purity melt into the pressure crystallizer at a flow rate of 20 kg / min, and applying an initial pressure of 2.0±0.2 MPa to perform micro-pressure casting to obtain a shaped melt;

[0069] S42, arrange 6 groups of water-cooled copper coils in the pressure crystallizer to form a pulsed magnetic field, set the peak magnetic field strength of the pulsed magnetic field to be 5.0±1T, the pulse frequency of the pulsed magnetic field to be 20±5Hz, and the magnetic field direction to be 0°-90°, take the peak magnetic field strength, the pulse frequency, and the magnetic field direction as the magnetic field parameters, and determine the magnetic field parameter range;

[0070] The pulsed magnetic field is started at the initial stage of solidification of the forming melt, vortex convection is generated in the melt to refine the grain size, high-pressure nitrogen gas is then introduced to strengthen heat exchange, the cooling rate is 80℃ / min in the temperature range of 580℃-400℃, the cooling rate is 30℃ / min in the temperature range of 400℃-200℃, the pressure is released and the mold is opened when the temperature drops to 150℃, and a primary aluminum alloy ingot is obtained; the primary aluminum alloy ingot is placed at a temperature of 120±2℃ for 10h, and then placed at a temperature of 170±2℃ for 8h, and finally an aluminum alloy ingot is obtained after water cooling;

[0071] S43, detect the grain size of the final aluminum alloy ingot using a high-temperature ultrasonic probe, detect the nano-phase size of the final aluminum alloy ingot using in-situ X-ray diffraction, and perform a salt spray corrosion resistance experiment on the final aluminum alloy ingot, record the corrosion resistance time, and the nano-phase size is the Al3(Sc,Zr) phase size; give the grain size, the nano-phase size, and the corrosion resistance time a weight coefficient respectively, and establish a target function wherein , and represent the weight coefficients, P represents the grain size, Q represents the nano-phase size, T represents the corrosion resistance time;

[0072] Take the target function as a fitness function, introduce a dynamic probability balance strategy and a cooperative evolution strategy to improve the whale optimization algorithm, obtain a mutated whale optimization algorithm, use the mutated whale optimization algorithm to optimize the magnetic field parameters, take the best fitness function value as the optimization target, and obtain the optimized magnetic field parameters, and the specific steps are as follows:

[0073] S431, set a search space according to the magnetic field parameter range, randomly generate a whale population, ensure that the positions of whale individuals are uniformly distributed in the magnetic field parameter range, set a whale individual in the whale population to represent a group of magnetic field parameters, and regard the process of optimizing the positions of whale individuals as the process of optimizing the magnetic field parameters;

[0074] set the current iteration number as t , the maximum iteration number as , adopt a dynamic probability balance strategy, set and represent random numbers between the interval [0, 1], and calculate a dynamic probability ;

[0075] S432、when the dynamic probability , at this time the whale population implements the contraction encirclement mechanism, the convergence factor is set and represent random numbers between the interval [0, 1], the encirclement coefficient and are calculated; the best whale individual position at the first iteration is t , the position of the i-th whale individual at the second iteration is , the distance between the whale individual position t and the best whale individual position i is calculated, the position of the i-th whale individual at the third iteration is , the distance between the whale individual position and the best whale individual position is calculated, and the position of the i-th whale individual at the fourth iteration is ; t i ;

[0076] when the dynamic probability , at this time the whale population implements the bubble net predation mechanism, the spiral shape parameter is set to , the distance between the current i-th whale individual position and the best whale individual position is i , represent random numbers between the interval [-1, 1], the whale individual position is updated again, and the position of the i-th whale individual at the fourth iteration is t ; i ;

[0077] S433, the whale population implements the random search target mechanism, introduces the cooperative evolution strategy, and sets the Levy flight distribution random vector using the Levy flight at this time, the first whale individual position is obtained by updating the whale individual position ; set represent random numbers between the interval [-1, 1], represent the sign function, represent the step scaling factor, the whale individual position is updated to obtain the second whale individual position , wherein represents element-wise multiplication;

[0078] the first whale individual position, the second whale individual position, and the i-th whale individual position at the third iteration are calculated i ​​​​The fitness function value corresponding to the position of each whale individual is selected, the position of the whale individual corresponding to the minimum fitness function value is selected, and the next iteration is entered until the current iteration number reaches the maximum iteration number, and a final whale population is obtained; the whale individual corresponding to the best fitness function value in the final whale population is found, and the optimized magnetic field parameters are obtained;

[0079] S44, the optimized magnetic field parameters include an optimized peak magnetic field strength, an optimized pulse frequency and an optimized magnetic field direction, the pulse magnetic field is readjusted, the melt is solidified in the magnetic field, and multi-stage heat treatment strengthening is performed, to obtain a corrosion-resistant aluminum alloy ingot;

[0080] In the embodiment, micro-pressure casting is carried out, a pulse magnetic field is set to dynamically control magnetic field parameters, multi-stage heat treatment strengthening is carried out, and a whale optimization algorithm is introduced to optimize the magnetic field parameters, so as to form a corrosion-resistant aluminum alloy ingot; the method utilizes a spiral Lorentz force generated by the pulse magnetic field to improve the efficiency of dendrite fragmentation, makes the corrosion propagation path tortuous, reduces the size of the nano-strengthening phase, and uniformly distributes the nano phase to effectively inhibit corrosion; a dynamic probability balance strategy and a cooperative evolution strategy are introduced to improve the whale optimization algorithm, so as to overcome the slow convergence speed of the traditional algorithm, balance the global search and local search capabilities, improve the global search performance and convergence speed, lock the optimal magnetic field parameters, greatly reduce the process cycle and preparation energy consumption, and comprehensively improve the corrosion resistance and tensile strength; specifically, for example, an ultrahigh-purity melt (temperature 665℃, hydrogen content ≤0.05ml / 100gAl), the ingot size is Φ300mm×1200mm, and a 50μm boron nitride coating is sprayed on the inner wall of the pressure crystallizer; during the pouring process, the average data is measured in real time, the melt temperature is 654.2℃, the pouring flow rate is 19.8kg / min, the initial pressure is 2.15MPa, the pressure holding time is 82min, and micro-pressure casting is carried out; the magnetic field parameters (before optimization) are as follows: peak magnetic field strength 5.0T, pulse frequency 20Hz, magnetic field direction 0° (axial direction), the pulse magnetic field is started, the melt vortex convection is controlled, and dynamic solidification is controlled until the pressure is released and the mold is opened at 150℃, and then multi-stage aging is carried out: first-stage aging: 120±2℃×10h, second-stage aging: 170±2℃×8h; the corrosion-resistant aluminum alloy ingot sample is weighed, the contribution rates of the grain size, nano phase size and corrosion resistance time to the yield strength and corrosion resistance are analyzed by regression analysis, the weight priorities are 0.4, 0.4 and 0.2 respectively, and the weight coefficients are obtained; the dynamic probability balance strategy and the cooperative evolution strategy are introduced to improve the whale optimization algorithm, the whale population is initialized, 50 whale individuals (magnetic field parameter combinations) are generated, and are uniformly distributed in [3.0-7.0T, 15-25Hz, 0°-90°]; each group of parameters is used to cast a Φ30mm small test sample, the fitness function value is calculated, the maximum iteration number is 30, the surrounding, predation and random search mechanisms are implemented, the Levy flight step length is 0.5, and the optimized magnetic field parameters are output: the optimized peak magnetic field strength is 6.3T, the optimized pulse frequency is 23.5Hz, and the optimized magnetic field direction is 52°; the main ingot solidification is controlled, and the corrosion-resistant aluminum alloy ingot is obtained; the grain size (μm) is measured by electron backscatter diffraction and is reduced from 92±15 before optimization to 63±8 after optimization (reduced by 31.5%); the Al3(Sc,Zr) phase size is detected by the half-height width of the diffraction peak in the X-ray diffraction spectrum and is reduced from 12.3nm before optimization to 7.8nm after optimization (reduced by 36.6%); the salt spray corrosion resistance time is increased from 1650h before optimization to 2280h after optimization (increased by 38.2%), and the corrosion speed can be effectively inhibited.

[0081] Embodiment 2

[0082] On the basis of example 1, different from example 1 is that the peak magnetic field strength of the pulsed magnetic field is optimized, and the pulse frequency and the magnetic field direction of the pulsed magnetic field are fixed; specifically, the peak magnetic field strength of the pulsed magnetic field is initially 5.7T, the pulse frequency of the pulsed magnetic field is fixed at 20Hz, and the magnetic field direction is fixed at 45°; using the mutation whale optimization algorithm, the search space is the pulse frequency range (3.0-7.0T), and the weight coefficients are 0.4, 0.4 and 0.2 respectively, and the search space is iteratively searched, and through the surrounding, predation, and random search mechanism, until 30 iterations, the algorithm converges to the optimized pulse frequency of 18Hz; control the main ingot solidification to obtain a corrosion-resistant aluminum alloy ingot, the grain size (μm) measured by electron backscatter diffraction is reduced from 92±15 before optimization to 82±12 after optimization (decreased by 10.9%), the Al3(Sc,Zr) phase size detected by the half-height width of the diffraction peak in the X-ray diffraction spectrum is reduced from 12.3nm before optimization to 10.3nm after optimization (decreased by 16.3%), and the salt spray corrosion resistance time is increased from 1650h before optimization to 1900h after optimization (increased by 15.1%); compared with example 1, the generated electromagnetic stirring force action time is shorter, which leads to limited grain refinement effect, resulting in larger Al3(Sc,Zr) phase size, uneven distribution, and reduced salt spray corrosion resistance.

[0083] Example 3

[0084] On the basis of example 1, different from example 1 is that the pulse frequency of the pulsed magnetic field is optimized, and the peak magnetic field strength and the magnetic field direction of the pulsed magnetic field are fixed; specifically, the pulse frequency of the pulsed magnetic field is initially 20Hz, the peak magnetic field strength of the pulsed magnetic field is fixed at 5.0T, and the magnetic field direction is fixed at 45°; using the mutation whale optimization algorithm, the search space is the peak magnetic field strength range (15-25Hz), and the weight coefficients are 0.4, 0.4 and 0.2 respectively, and the search space is iteratively searched, and through the surrounding, predation, and random search mechanism, until 30 iterations, the algorithm converges to the optimized pulse frequency of 18Hz; control the main ingot solidification to obtain a corrosion-resistant aluminum alloy ingot, the grain size (μm) measured by electron backscatter diffraction is reduced from 92±15 before optimization to 85±12 after optimization (decreased by 7.6%), the Al3(Sc,Zr) phase size detected by the half-height width of the diffraction peak in the X-ray diffraction spectrum is reduced from 12.3nm before optimization to 10.1nm after optimization (decreased by 17.9%), and the salt spray corrosion resistance time is increased from 1650h before optimization to 1880h after optimization (increased by 13.6%); compared with example 1, the grains are larger, forming more corrosion channels, accelerating the expansion of pitting corrosion, the Al3(Sc,Zr) phase size is larger, and the nano-phase is prone to coarsening.

[0085] Example 4

[0086] On the basis of example 1, different from example 1 is that the magnetic field direction is optimized, the peak magnetic field strength of the pulsed magnetic field and the pulse frequency of the pulsed magnetic field are fixed; specifically, the magnetic field direction is initially 45°, the peak magnetic field strength of the pulsed magnetic field is fixed at 5.0T, and the pulse frequency of the pulsed magnetic field is fixed at 20Hz; using the mutation whale optimization algorithm, the search space is the magnetic field direction range (0°-90°), the weight coefficients are 0.4, 0.4 and 0.2 respectively, and the search space is iteratively searched, and through the surrounding, predation and random search mechanism, until 30 iterations, the optimized magnetic field direction is 60°. The algorithm converges. Control the main ingot solidification to obtain a corrosion-resistant aluminum alloy ingot, and use electron backscatter diffraction to measure the grain size (μm) to reduce from 92±15 before optimization to 86±12 after optimization (4.3% reduction), use the half-height width of the diffraction peak in the X-ray diffraction spectrum to detect the Al3(Sc,Zr) phase size to reduce from 12.3nm before optimization to 11.0nm after optimization (10.6% reduction), and the salt spray corrosion resistance time increases from 1650h before optimization to 1780h after optimization (7.9% increase); compared with example 1, the grains are relatively coarse and locally enriched, resulting in coarsening of the nano-phase, adjusting the Lorentz force direction to strengthen the level of vortex convection and layered stirring, and only the magnetic field direction optimization effect is weaker than the peak strength or frequency optimization.

[0087] Example 5

[0088] On the basis of example 1, different from example 1 is that the inert gas gradient melting method is not used, and the temperature is directly raised to 950℃ for melting, and the Al-Sr intermediate alloy is not buried for adding, and the purity 99.999% argon is not filled; specifically, high-purity magnesium ingots with a mass fraction of more than 99.95wt% are weighed and placed in a vacuum induction melting furnace, and argon with a purity of 99.9% is filled as a protective gas. The intermediate alloy and high-purity aluminum ingots are directly heated to 950℃ for melting, and the Al-Sr intermediate alloy is directly added for melting to obtain a pre-alloyed melt; since there is no purity 99.999% argon protection to block the reaction of Sr with oxygen (4Sr + O2→ 2SrO), and 950℃ direct melting, without buried addition, the volatilization caused by the vapor pressure (Sr boiling point 1380℃, high temperature oxidation accelerates loss), makes Sr foil rapidly oxidized and burned, resulting in the failure of modification effect; compared with example 1, the Sr burnout rate is 30.2% at this time, the composition distribution uniformity deviation obtained by electron probe face scanning is ≥15wt%, SrO dross is generated on the surface, resulting in larger Al3(Sc,Zr) phase size and uneven distribution, and the corrosion resistance decreases.

[0089] Example 6

[0090] On the basis of embodiment 1, different from embodiment 1, no rotary injection refining and ultrasonic-plasma coupling treatment are used to remove impurities; specifically, 45wt% of MgCl2, 30wt% of KCl, 20wt% of MgF2 and 5wt% of CeCl3 are weighed according to the mass ratio, mixed and pressed into particles to obtain a refining agent, 1.5kg of the refining agent is directly put into the pre-alloyed melt at a usage of 1t of the pre-alloyed melt to obtain a refined pre-alloyed melt; Ar and SF6 mixed gas is uniformly dispersed under the action of centrifugal force to adsorb and float the inclusions, no rotary injection refining is used so that Al2O3 in the melt cannot float and gather into clusters, at the same time, a titanium alloy ultrasonic probe and a non-transferred arc plasma beam are inserted, cavitation effect is used to break inclusions below 10μm, arc ionizes gas, evaporates dross, and no ultrasonic-plasma coupling treatment is used so that submicron Al2O3 becomes a crack source; compared with embodiment 1, according to the particle size statistics of a scanning electron microscope (SEM), the inclusion density decreases from an initial value of 8.7×10 5 / cm³ to 3.3×10 5 / cm³ (a decrease of 62.1%), and the maximum inclusion size decreases from an initial value of 12.5μm to 12.0μm (a decrease of 4%); the existence of large Al2O3 clusters in the melt causes the maximum inclusion size to remain basically unchanged, the inclusions cause brittle fracture, and affect the mechanical properties of the corrosion-resistant aluminum alloy ingot.

[0091] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the invention. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0092] The preferred embodiments of the above disclosed invention are only used to help explain the invention. The preferred embodiments do not describe all the details and limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of the present specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the invention, so that those skilled in the art can well understand and utilize the invention.

Claims

1. A method for preparing a corrosion-resistant aluminum alloy ingot, characterized by comprising the following steps: S1. Gradient melting: Weigh the initial raw materials according to the mass ratio, pre-synthesize the intermediate alloy, weigh the high-purity magnesium ingot, and use the inert gas gradient melting method to melt the intermediate alloy and the high-purity magnesium ingot in a stepwise heating process to obtain the pre-alloyed melt. S2. Co-refining: Prepare a refining agent, simultaneously introduce mixed gas to perform rotary spray refining on the pre-alloyed melt, and then perform ultrasonic-plasma coupling treatment to remove impurities to obtain a deeply purified melt. S3. Filtration and separation: Construct a multi-stage filtration device to perform vacuum membrane separation and impurity removal on the deep-purified melt to obtain an ultra-high purity melt. S4. Ingot solidification: The ultra-high purity melt is micro-pressure cast to obtain a shaped melt. The magnetic field parameters are dynamically controlled by a pulse magnetic field. The shaped melt is solidified in the pulse magnetic field and then subjected to multi-stage heat treatment to strengthen it and obtain the final aluminum alloy ingot. The magnetic field parameters are optimized by introducing a whale optimization algorithm to form a corrosion-resistant aluminum alloy ingot. The process of introducing the whale optimization algorithm to optimize magnetic field parameters and form corrosion-resistant aluminum alloy ingots includes the following steps: The grain size, nanophase size, and corrosion resistance time of the final aluminum alloy ingot were detected, and an objective function was established. Using the objective function as the fitness function, the whale optimization algorithm is improved to obtain the mutant whale optimization algorithm; A whale population is randomly generated to ensure that the positions of individual whales are evenly distributed within the range of magnetic field parameters. Each individual whale in the population is defined as a set of magnetic field parameters, and the process of optimizing the position of individual whales is regarded as the process of optimizing magnetic field parameters. Calculate dynamic probabilities and update individual whale positions by different mechanisms when whale populations enter; By introducing a cooperative evolution strategy, the position of the whale individual corresponding to the minimum fitness function value is selected to enter the next iteration, resulting in the final whale population. The whale individual corresponding to the optimal fitness function value is then found to obtain the optimized magnetic field parameters. The pulsed magnetic field is readjusted according to the optimized magnetic field parameters. The molten material is solidified in the adjusted pulsed magnetic field and then subjected to multi-stage heat treatment to strengthen it, resulting in a corrosion-resistant aluminum alloy ingot. The raw materials for preparing the corrosion-resistant aluminum alloy ingot include: Al-Sr master alloy, Al-Ti-B-Sc master alloy, high-purity magnesium ingot, Al-Mn master alloy, Al-Cr master alloy, Al-Hf master alloy and Al-Zr master alloy.

2. The method for preparing a corrosion-resistant aluminum alloy ingot according to claim 1, characterized in that, The pre-synthesized intermediate alloy includes the following steps: Weigh out high-purity aluminum ingots with a purity of 99.99 wt% and Sr foil with a purity of 99.5 wt% according to the mass ratio, and place them in an argon-protected induction furnace to prepare an Al-Sr master alloy. Titanium sponge, KBF4 powder, and Sc2O3 nanoparticles were weighed out according to a mass ratio of 5:1:0.2, and then combined with high-purity aluminum ingots to prepare an Al-Ti-B-Sc master alloy.

3. The method for preparing a corrosion-resistant aluminum alloy ingot according to claim 2, characterized in that, The inert gas gradient melting method includes the following steps: Weigh out high-purity magnesium ingots with a purity higher than 99.95 wt% according to the specified mass ratio, place them in a vacuum induction melting furnace, and evacuate to 10 ppm. -2 After Pa, argon gas with a purity of 99.999% is introduced. The stepped heating melting process is set to include a first stage, a second stage, a third stage, and a fourth stage. In the first stage, the temperature is maintained at 700±5℃, Al-Mn and Al-Cr master alloys are added, axial electromagnetic stirring is applied, and the process is continued for 15 minutes. In the second stage, the temperature is maintained at 750±5℃, Al-Hf and Al-Zr master alloys are added, electromagnetic stirring is applied simultaneously, and the process is held for 30 minutes. In the third stage, the temperature is maintained at 680±5℃, Al-Sr master alloy is added by embedding, and high-purity magnesium ingots are added. In the fourth stage, the temperature is maintained at 640±5℃, Al-Ti-B-Sc master alloy is added, and the temperature is held for 10 minutes to obtain a pre-alloyed melt.

4. The method for preparing a corrosion-resistant aluminum alloy ingot according to claim 3, characterized in that, The preparation of the refining agent, and the simultaneous introduction of mixed gas to perform rotary blowing refining of the pre-alloyed melt, includes the following steps: Weigh out 45±5wt% MgCl2, 30±2wt% KCl, 20±2wt% MgF2 and 5±0.5wt% CeCl3 according to the mass ratio, mix them and press them into granules to obtain a refining agent, then put it into a rotary jetting device and continuously introduce a mixture of Ar and SF6 gas. The rotary jetting device is started to obtain a refined alloying melt.

5. The method for preparing a corrosion-resistant aluminum alloy ingot according to claim 4, characterized in that, The process of removing impurities by ultrasonic-plasma coupling includes the following steps: The refined alloying melt is cooled to 670±5℃, a titanium alloy ultrasonic probe is inserted, and a non-transfer arc plasma beam is applied above the refined alloying melt to obtain a deeply purified melt.

6. The method for preparing a corrosion-resistant aluminum alloy ingot according to claim 5, characterized in that, The vacuum membrane separation and impurity removal of the deeply purified melt includes the following steps: An alumina ceramic filter tank and a yttrium-stabilized zirconia porous membrane separator are obtained to construct a multi-stage filtration device. The deep-purified melt is injected into the alumina ceramic filter tank, and impurities are filtered by gravity to obtain a filtered melt. The melt then flows through the yttrium-stabilized zirconia porous membrane separator to obtain an ultra-high purity melt.

7. The method for preparing a corrosion-resistant aluminum alloy ingot according to claim 6, characterized in that, The process of micro-compression casting the ultra-high purity melt to obtain a shaped melt, setting a pulsed magnetic field to dynamically control the magnetic field parameters, solidifying the shaped melt in the pulsed magnetic field, and then performing multi-stage heat treatment to strengthen it and obtain the final aluminum alloy ingot includes the following steps: A pressure crystallizer is configured, and a boron nitride coating is sprayed onto the inner wall of the pressure crystallizer. The ultra-high purity melt is cooled to 655±3℃, and the ultra-high purity melt is poured into the pressure crystallizer while applying pressure to perform micro-pressure casting to obtain a shaped melt. A water-cooled copper coil is arranged in the pressure crystallizer to form a pulsed magnetic field. The magnetic field parameters are dynamically controlled by setting the pulsed magnetic field parameters, and the peak magnetic field strength, pulse frequency and magnetic field direction are used as magnetic field parameters to determine the range of magnetic field parameters. The pulsed magnetic field is activated at the initial stage of solidification of the molten metal. High-pressure nitrogen is introduced to enhance heat exchange. When the temperature drops to 150℃, the pressure is released and the mold is opened to obtain a primary aluminum alloy ingot. The primary aluminum alloy ingot is placed at a temperature of 120±2℃ for 10 hours, then placed at a temperature of 170±2℃ for 8 hours, and finally water-cooled to obtain the final aluminum alloy ingot.

8. The method for preparing a corrosion-resistant aluminum alloy ingot according to claim 7, characterized in that, The raw materials for preparation include Al-Sr master alloy with Sr content of 20±0.5wt%, high-purity magnesium ingot with purity higher than 99.95wt%, Al-Mn master alloy with Mn content of 10±0.5wt%, Al-Cr master alloy with Cr content of 5±0.2wt%, Al-Hf master alloy with Hf content of 8±0.5wt%, and Al-Zr master alloy with Zr content of 4±0.2wt%.

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