CN114277271B

CN114277271B - High-strength composite modified aluminum alloy product and preparation method thereof

Info

Publication number: CN114277271B
Application number: CN202111611895.9A
Authority: CN
Inventors: 彭以辉; 答建成
Original assignee: Lianyungang Xingyao Material Technology Co ltd
Current assignee: Lianyungang Xingyao Material Technology Co ltd
Priority date: 2021-12-27
Filing date: 2021-12-27
Publication date: 2022-09-30
Anticipated expiration: 2041-12-27
Also published as: CN114277271A; EP4353854A1; WO2023125265A1; KR20240029059A

Abstract

The invention provides a high-strength composite modified aluminum alloy product and a preparation method thereof. The preparation method comprises the following steps: step S1, providing an aluminum alloy melt; step S2, providing a modifier; step S3, adding the modifier into the aluminum alloy melt and smelting the aluminum alloy melt in an inert gas atmosphere to obtain a modified aluminum alloy melt; step S4, casting by using the modified aluminum alloy melt to obtain a casting aluminum alloy biscuit; step S5, performing heat treatment on the modified aluminum alloy biscuit, wherein the heat treatment comprises the following steps: solution treatment, namely heating the aluminum alloy biscuit to the temperature of 530 ℃ and 550 ℃, and preserving heat for 300 min; quenching treatment, namely adding the aluminum alloy biscuit subjected to the solution treatment into a water bath at the temperature of 60-70 ℃ for quenching for 2-4 min; and (3) aging treatment, namely, preserving the heat of the aluminum alloy biscuit subjected to the quenching treatment at the temperature of 150-165 ℃ for 280min, then cooling to the temperature of 110-130 ℃ and preserving the heat for 30-120min, and then naturally cooling to the room temperature to obtain the high-strength composite modified aluminum alloy part.

Description

High-strength composite modified aluminum alloy product and preparation method thereof

Technical Field

The invention relates to the technical field of alloy materials and preparation, in particular to a high-strength composite modified aluminum alloy product and a preparation method thereof.

Background

Aluminum alloys are the most widely used class of non-ferrous structural materials in industry and have found a number of applications in the aerospace, automotive, mechanical manufacturing, marine and chemical industries. The cast aluminum alloy has the characteristics of good casting fluidity, good air tightness, small shrinkage, small hot cracking tendency and the like, and becomes a preferred material for the lightweight of the automobile hub.

However, the demand for aluminum alloys is also increasing, and not only the original light weight characteristics are maintained, but also certain strength is required, especially in the production of automobile parts and industries. For casting large-sized parts of aluminum alloys, high strength and medium toughness are required to solve the mechanical property problem.

For this reason, a process of modifying it with a modifier such as an aluminum strontium alloy and refining it in combination with a refiner has been proposed. However, the conventional modification still cannot obtain the desired strength and plasticity. On the basis of this, studies on heat treatment of cast aluminum alloys have been conducted. However, because of the composition difference of aluminum alloy parts and components, the heat treatment steps are different, the current heat treatment needs high temperature, consumes large energy, is long in time, increases the treatment cost, and is not beneficial to the mutual transformation of various phases and the uniform desolventizing due to the direct adoption of higher temperature for treatment, thereby causing the non-uniform mechanical properties of the alloy.

Therefore, it is highly desirable to provide a preparation process capable of further improving the mechanical strength of the aluminum alloy product.

Disclosure of Invention

In view of this, the present invention provides a high-strength composite modified aluminum alloy product capable of further improving the mechanical strength of the aluminum alloy, and a preparation method thereof.

In order to solve the technical problems, the invention adopts the following technical scheme:

the preparation method of the high-strength composite modified aluminum alloy product according to the embodiment of the first aspect of the invention comprises the following steps:

step S1, providing an aluminum alloy melt;

step S2, providing a modifier;

wherein the modifier is the combination of rare earth aluminum alloy, aluminum strontium intermediate alloy, aluminum titanium or aluminum titanium boron intermediate alloy,

or the modifier is the combination of composite rare earth aluminum alloy, aluminum titanium or aluminum titanium boron intermediate alloy, the composite rare earth aluminum alloy contains strontium, titanium or titanium boron and rare earth metal,

the rare earth metal in the rare earth aluminum alloy and the composite rare earth aluminum alloy is any one or more of lanthanum, cerium and yttrium;

step S3, adding the modifier into the aluminum alloy melt and smelting to obtain a modified aluminum alloy melt in an inert gas atmosphere;

step S4, casting the modified aluminum alloy melt to obtain a modified aluminum alloy biscuit;

step S5, performing heat treatment on the modified aluminum alloy biscuit, wherein the heat treatment comprises the following steps:

solution treatment, namely heating the modified aluminum alloy biscuit to the temperature of 530 ℃ and 550 ℃, and preserving the heat for 300 min;

quenching treatment, namely adding the aluminum alloy biscuit subjected to the solution treatment into a water bath at the temperature of 60-70 ℃ for quenching for 2-4 min;

and (3) aging treatment, namely preserving the heat of the aluminum alloy biscuit subjected to the quenching treatment at the temperature of 150-165 ℃ for 280min, then cooling to the temperature of 110-130 ℃ and preserving the heat for 30-120min, and then naturally cooling to the room temperature to obtain the high-strength composite modified aluminum alloy part.

Further, the step S1 includes:

providing an aluminum alloy mother ingot;

removing the surface oxide layer of the aluminum alloy mother ingot, and cleaning and drying the aluminum alloy mother ingot;

smelting the dried aluminum alloy mother ingot, refining and deslagging to obtain the aluminum alloy melt,

the aluminum alloy mother ingot comprises a hypoeutectic aluminum alloy or a eutectic aluminum alloy.

According to some embodiments of the invention, the modifier is a combination of a rare earth aluminum alloy, an aluminum strontium master alloy, an aluminum titanium or an aluminum titanium boron master alloy, wherein the aluminum strontium master alloy is added spaced apart from the aluminum titanium or aluminum titanium boron master alloy,

the rare earth aluminum alloy is firstly added, or is added together with the firstly added part, or is added in a gap between the aluminum strontium intermediate alloy and the aluminum titanium or aluminum titanium boron intermediate alloy.

Further, the step S3 includes:

step S301, adding the rare earth aluminum alloy into the aluminum alloy melt and smelting to obtain a first uniform mixed melt;

step S302, adding the aluminum-strontium intermediate alloy into the first uniformly mixed melt and continuously smelting to obtain a second uniformly mixed melt;

step S303, adding the aluminum-titanium or aluminum-titanium-boron intermediate alloy into the second uniformly mixed melt and continuously smelting to obtain the modified aluminum alloy.

According to other embodiments of the present invention, the modifier is a combination of a composite rare earth aluminum alloy, aluminum titanium or an aluminum titanium boron intermediate alloy, and the step S3 includes:

step S310, adding the composite rare earth aluminum alloy into the aluminum alloy melt and smelting to obtain a fourth uniform mixed melt;

step S320, adding the aluminum-titanium or aluminum-titanium-boron intermediate alloy into the fourth uniformly mixed melt and continuously smelting to obtain the modified aluminum alloy.

Further, the preparation of the composite rare earth aluminum alloy comprises the following steps:

step S211, providing the aluminum melt;

step S212, providing an aluminum-strontium intermediate alloy, an aluminum-titanium or aluminum-titanium-boron intermediate alloy and a rare earth-aluminum intermediate alloy, wherein the rare earth metal in the rare earth-aluminum intermediate alloy is one or more selected from lanthanum, cerium and yttrium;

and S213, sequentially adding the rare earth aluminum intermediate alloy, the aluminum strontium intermediate alloy and the aluminum titanium or aluminum titanium boron intermediate alloy into the aluminum melt in an inert gas atmosphere, and smelting to obtain the composite rare earth alloy.

Further, the modifier accounts for 0.4-0.6wt% of the total amount of the modified aluminum alloy melt, and the ratio of the rare earth metal: strontium: the mass ratio of the total amount of titanium or titanium boron is 1 (0.1-1.2): (0.1-1.2).

Further, in the step S5, the temperature rise rate in the solution treatment is controlled to be 1.5-3 ℃/min, and the heat preservation time is controlled to be 120-180 min.

Further, the solution treatment, the quenching treatment, and the aging treatment are continuous treatments, and the water bath is a circulating water bath, and after the quenching treatment, the temperature of the cast aluminum alloy biscuit is maintained at 55 ℃ or higher before the aging treatment.

Further, in the aging treatment stage, the temperature reduction rate from 150-165 ℃ to 110-130 ℃ is controlled at 2-5 ℃/min.

According to the high-strength composite modified aluminum alloy part prepared by the preparation method of any one of the embodiments, the tensile strength of the high-strength aluminum alloy part is more than 300MPa, the yield strength of the high-strength aluminum alloy part is more than 230MPa, and the elongation of the high-strength aluminum alloy part is more than 6%.

The technical scheme of the invention at least has one of the following beneficial effects:

according to the preparation method of the high-strength composite modified aluminum alloy part, rare earth metal is introduced to modify the aluminum alloy, and the casting part is treated by combining a specific heat treatment process, so that the mechanical strength of the casting part can be greatly improved to meet the requirements of the fields of aviation, aerospace, automobiles and the like, the toughness of the casting part can be improved, and the occurrence of brittle fracture and the like can be reduced.

Drawings

FIG. 1 is a photograph of a high strength composite modified aluminum alloy article, a wheel hub, made in accordance with example 1;

fig. 2 is a metallographic image of the rib portion of the hub shown in fig. 1, wherein (a) is a low-power image, (b) is a medium-power image, and (c) is a high-power image.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one.

The method for preparing the high-strength composite modified aluminum alloy product according to the embodiment of the invention is first described in detail.

The preparation method of the high-strength composite modified aluminum alloy part comprises the following steps:

step S1, providing an aluminum alloy melt.

That is, an aluminum alloy melt is first prepared.

Here, it should be noted that a commercially available high-purity aluminum alloy ingot may be directly heated and melted to prepare an aluminum alloy melt, or the aluminum alloy ingot may be further purified. The purification treatment may, for example, comprise the following steps:

step S11, providing an aluminum alloy ingot;

step S12, removing an oxide scale layer on the surface of the aluminum alloy ingot;

step S13, cleaning and drying the aluminum alloy ingot with the oxide scale layer removed;

step S14, smelting the dried aluminum alloy ingot to obtain an initial melt;

and step S15, refining the initial melt to obtain the aluminum alloy melt.

That is, for the aluminum alloy ingot, the scale layer on the surface thereof is first removed, thereafter, cleaning is performed to remove surface floating chips, and after drying, melting is performed, and the melt is refined. Details regarding the specific refining process will be described later.

After the above purification treatment, undesired impurities such as Fe, oxides, etc. can be removed therefrom. Is favorable for further improving the modification and refinement of the rare earth alloy.

It should be noted that, in this case, Fe and its oxide may be removed by adding manganese or an aluminum-manganese alloy to form surface scum, for example.

The modified matrix, i.e., the aluminum alloy melt, may be, for example, an aluminum-magnesium alloy, an aluminum-silicon-magnesium alloy, or the like, and the present invention is not particularly limited thereto.

Step S2, providing a modifier.

Wherein the modifier is the combination of rare earth aluminum alloy, aluminum strontium intermediate alloy, aluminum titanium or aluminum titanium boron intermediate alloy, or the combination of composite rare earth aluminum alloy, aluminum titanium or aluminum titanium boron intermediate alloy,

the composite rare earth aluminum alloy contains strontium, titanium or titanium boron and rare earth metal,

the rare earth aluminum alloy and the rare earth metal in the composite rare earth aluminum alloy are any one or more of lanthanum, cerium and yttrium.

That is, there are two embodiments as follows:

the first implementation mode comprises the following steps:

the modifier is a combination of rare earth aluminum alloy, aluminum-strontium intermediate alloy, aluminum-titanium or aluminum-titanium-boron intermediate alloy.

The aluminum-strontium intermediate alloy is a modifier, and the aluminum-titanium intermediate alloy or the aluminum-titanium-boron intermediate alloy is a refiner. That is, conventional modifiers and refiners may be used.

Further, the modifier and/or the refiner can be made of commercially available materials, or can be made by weighing the corresponding metals strontium, titanium & boron, respectively, and melting the metals in an aluminum melt to form a uniform alloy.

In addition, rare earth aluminum alloys have been further introduced in addition to conventional modifiers and refiners to overcome the limitation of mechanical properties due to the "poisoning" reaction between the modifier and the refiners. As the rare earth metal in the rare earth aluminum alloy, a group IIIB element having an electronic structure intervening therebetween may be selected in consideration of strontium in the modifier and titanium and boron in the refiner. Considering stability, resources and the like, preferably, one or more of yttrium, lanthanum in lanthanide metals and cerium are adopted. The rare earth aluminum alloy may be one or more of commercially available Al-10Ce, Al-20La, Al-10La and Al-20Y, Al-10Y.

In addition, the rare earth aluminum alloy can be prepared by self, and can be prepared by the following method:

adding the rare earth metal or the intermediate alloy containing the rare earth metal into the aluminum melt under inert atmosphere, and stirring the mixture to be completely molten while heating the mixture;

after the materials are completely melted, continuously preserving the heat for 10 to 20 minutes to homogenize the materials;

refining the homogenized melt;

and standing for a preset time after refining, and pouring to obtain the rare earth aluminum alloy.

The aluminum melt may be a commercially available high-purity aluminum ingot, and the corresponding treatment is performed by referring to the purification treatment of the aluminum alloy ingot, which is not described herein again.

In addition, for the commercial aluminum strontium intermediate alloy, aluminum titanium intermediate alloy or aluminum titanium boron intermediate alloy, rare earth aluminum alloy, respectively, the descaling, ultrasonic cleaning and refining treatment can be sequentially carried out. Thereby, undesirable impurities and oxides can be further removed, and the refining and modification effects of the composite rare earth alloy as a product can be improved.

The second embodiment:

the modifier is a combination of a composite rare earth aluminum alloy, aluminum titanium or an aluminum titanium boron intermediate alloy.

The composite rare earth aluminum alloy can be prepared by smelting and refining the rare earth aluminum alloy, the aluminum-strontium intermediate alloy, the aluminum-titanium or aluminum-titanium-boron intermediate alloy and the aluminum melt.

For example, the preparation of the composite rare earth aluminum alloy may include:

step S211, providing an aluminum melt;

step S212, providing an aluminum-strontium intermediate alloy, an aluminum-titanium or aluminum-titanium-boron intermediate alloy and a rare earth aluminum alloy, wherein the rare earth metal in the rare earth aluminum alloy is one or more selected from lanthanum, cerium and yttrium;

step S213, adding the rare earth aluminum alloy, the aluminum strontium intermediate alloy, the aluminum titanium or the aluminum titanium boron intermediate alloy into the aluminum melt in an inert gas atmosphere, and smelting to obtain the composite rare earth alloy.

The aluminum-strontium intermediate alloy and the aluminum-titanium or aluminum-titanium-boron intermediate alloy are added at intervals, and the rare earth aluminum alloy is added before the aluminum-strontium intermediate alloy and the aluminum-titanium or aluminum-titanium-boron intermediate alloy, or is added together with the first-added intermediate alloy, or is added in a gap between the aluminum-strontium intermediate alloy and the aluminum-titanium or aluminum-titanium-boron intermediate alloy.

Preferably, the rare earth aluminum alloy, the aluminum strontium intermediate alloy, the aluminum titanium or the aluminum titanium boron intermediate alloy are sequentially added into the aluminum melt at intervals.

And step S3, adding the modifier into the aluminum alloy melt and smelting in an inert gas atmosphere to obtain the modified aluminum alloy melt.

That is, after preparing the aluminum melt and the modifier, the modifier is added to the aluminum melt under an inert gas atmosphere for further melting to obtain a modified aluminum alloy melt.

According to the preparation method provided by the embodiment of the invention, the rare earth metal is introduced into the modifier, so that the mutual poisoning effect between the modifier and the refiner is greatly overcome, the addition amounts of the modifier and the refiner can be increased, and the modification and refinement effects can be improved.

The two combined modifiers were melted as follows.

Aiming at the combination that the modifier is rare earth aluminum alloy, aluminum strontium intermediate alloy, aluminum titanium or aluminum titanium boron intermediate alloy:

specifically, each of the rare earth aluminum alloy, the aluminum strontium intermediate alloy, the aluminum titanium or aluminum titanium boron intermediate alloy, and the pretreatment thereof may refer to the above step S2.

In the case of this combination, wherein the aluminum strontium master alloy is added spaced apart from the aluminum titanium or aluminum titanium boron master alloy, the rare earth aluminum alloy is added first, or with the first addition, or in the aluminum strontium master alloy and the aluminum titanium or aluminum titanium boron master alloy.

Further preferably, the step S3 may specifically include:

step S301, adding the rare earth aluminum alloy into the aluminum melt and smelting to obtain a first uniform mixed melt;

step S302, adding the aluminum-strontium intermediate alloy into the first uniform mixed melt and continuously smelting to obtain a second uniform mixed melt;

That is, by adding the rare earth aluminum alloy and smelting, and then sequentially adding the aluminum strontium intermediate alloy as the modifier and the aluminum titanium intermediate alloy or the aluminum titanium boron intermediate alloy as the refiner at intervals on the basis, the poisoning effect of strontium and boron can be better solved, and the modified aluminum alloy which is more refined and uniform and has higher mechanical property can be obtained.

In addition, for the combination of the modifier being a composite rare earth aluminum alloy, aluminum titanium or an aluminum titanium boron intermediate alloy, the step S3 includes:

step S310, adding the composite rare earth aluminum alloy into the aluminum melt and smelting to obtain a fourth uniform mixed melt;

That is, when the rare earth aluminum alloy, the modifier, the refiner and the aluminum are melted in advance to prepare the composite rare earth aluminum alloy, the rare earth aluminum alloy can be added to the aluminum melt at one time for preparation. Of course, considering that abnormal growth of crystal grains is likely to occur in the case of high-temperature melting, which is not favorable for improving the mechanical properties, it is preferable that a refiner, i.e., an aluminum-titanium intermediate alloy or an aluminum-titanium-boron intermediate alloy, be further added to control the crystal grain growth in the case where the composite rare earth aluminum alloy is completely melted and uniformly mixed with the aluminum alloy.

The addition amount of the modifier is designed according to the use requirement and the content of each effective component in the master alloy. As an example, for example, in the case of being introduced by a composite rare earth alloy in which the rare earth element contained is strontium to titanium or titanium boron in a total mass ratio of 1 (0.1 to 1.2) to (0.1 to 1.2), the modifier preferably accounts for 0.4 to 0.6wt% of the total amount of the modified aluminum alloy.

Further, the refining in any one of the above steps, i.e., the refining in the purification process of the aluminum melt, the refining in the preparation process of the rare earth aluminum alloy, and the refining of each melt in the composite rare earth aluminum alloy, may be performed in the following manner:

blowing the refining agent by inert gas and keeping for 3-10 minutes, then adding deslagging agent and stirring for 5-10 minutes, and removing the surface scum.

Furthermore, the adding amount of the refining agent accounts for 0.1-0.3% of the mass of the added melt, and the adding amount of the slag removing agent accounts for 0.1-0.3% of the mass of the added melt;

the refining agent comprises the following components in percentage by mass:

10-15 parts of potassium chloride, 15-25 parts of sodium chloride, 8-15 parts of calcium fluoride, 15-25 parts of sodium carbonate, 8-12 parts of sodium sulfate, 10-20 parts of sodium fluoroaluminate and 8-12 parts of hexachloroethane;

the slag remover comprises the following components in percentage by mass:

25-30 parts of sodium chloride, 25-30 parts of potassium chloride, 5-10 parts of sodium carbonate, 5-10 parts of sodium sulfate, 1-5 parts of sodium fluoroaluminate, 5-10 parts of sodium fluosilicate, 5-10 parts of calcium fluoride, 1-5 parts of potassium nitrate and 5-10 parts of potassium fluosilicate.

Further, it may be determined whether refining continues by monitoring the hydrogen content of the melt. In the present invention, the hydrogen content is estimated by measuring the density of the melt, that is, the closer the melt density is to its theoretical density (slightly different depending on the components contained in the alloy, approximately 2.7 g/cm) ³ Left and right) indicates that the lower the hydrogen content therein. For example, the density of the melt may be set to less than 2.65g/cm ³ If so, carrying out the refining treatment; when the melt density is more than or equal to 2.65g/cm ³ I.e., not performing the refining process or terminating the refining process.

And step S4, casting the modified aluminum alloy melt to obtain a casting aluminum alloy biscuit.

That is, after melting, the resulting modified aluminum alloy melt is cast into a mold to obtain the cast aluminum alloy biscuit.

In the specific casting process, a conventional casting process may be used, and a detailed description thereof is omitted.

And step S5, performing heat treatment on the aluminum alloy biscuit.

That is, after obtaining an aluminum alloy green compact by casting, in order to further improve the mechanical strength thereof, the inventors have developed the following heat treatment process based on repeated studies:

specifically, the heat treatment includes:

solution treatment, namely heating the aluminum alloy biscuit to the temperature of 530 ℃ and 550 ℃, and preserving the heat for 300 min;

Namely, the aluminum alloy biscuit is subjected to solution treatment, quenching treatment and aging treatment in sequence.

By designing the solution treatment, the stress caused by the cooling speed when the casting is crystallized and solidified due to casting structures (such as uneven wall thickness and large thickness of a transition) and the like can be eliminated; the mechanical strength and the hardness of the alloy are improved, and the metallographic structure is improved; eliminate intergranular and compositional segregation and homogenize the structure.

In addition, the quenching treatment is designed to rapidly cool the casting, so that the strengthening component is dissolved in the alloy to the maximum extent and is fixedly stored to the room temperature.

By designing the aging treatment, the temperature rise and the time extension are about to generate a solute atom enrichment region (named as a G-PII region) and a G-PII region to disappear through recombination of atoms in a supersaturated solid solution lattice, second phase atoms are deviated and generate the G-PII region according to a certain rule, a metastable second phase (transition phase) is generated, a large number of G-PII regions are combined with a small number of metastable phases, and the metastable phases are converted into stable phases and second phase particles are aggregated.

In addition, according to the preparation method of the present invention, the high temperature aging treatment is first applied so that the phase transition mainly occurs between the β' region and the β "region, thereby enabling to secure high strength.

Preferably, the temperature rise rate in the solid solution treatment is controlled to be 1.5-3 ℃/min, and the heat preservation time is controlled to be 120-180 min. By controlling the heating rate and the heat preservation time of the solution treatment, the rose-shaped alpha-Al phase and the round spherical alpha-Al phase can be further increased, the primary alpha-Al phase is refined, and the number of dendrites is reduced.

Further, the solution treatment, the quenching treatment, and the aging treatment are continuous treatments, and the water bath is a circulating water bath, and after the quenching treatment, the temperature of the cast aluminum alloy biscuit is maintained at 55 ℃ or higher before the aging treatment. Through continuous processing, not only can the production efficiency be improved, but also unnecessary defects caused by process interruption can be avoided. And the lowest temperature in the period is controlled, so that the defect caused by rapid temperature reduction is avoided.

Further, in the aging treatment stage, the temperature reduction rate from 150-165 ℃ to 110-130 ℃ is controlled at 2-5 ℃/min. By controlling the cooling rate in the aging treatment stage, the introduction of defects can be greatly reduced, the mechanical strength of the alloy can be further improved, and the properties can be kept at a higher level. Hereinafter, the production method according to the present invention is further described in detail by specific examples.

Example 1

Aluminum alloy: adopts aluminum-silicon-magnesium alloy (A356) (from Shandong Weiqiao aluminum industry)

High purity aluminum ingot (purchased from medium aluminum group, composition: Al (99.99%), Fe < 0.1%, impurity < 0.05%)

Refining agent:

the components: 15 parts of potassium chloride, 20 parts of sodium chloride, 210 parts of CaF, 320 parts of Na2CO, 410 parts of Na2SO, 615 parts of Na3AlF and 610 parts of C2 Cl.

Deslagging agent:

the components: 25 parts of sodium chloride, 25 parts of potassium chloride, 5 parts of sodium carbonate, 5 parts of sodium sulfate, 5 parts of sodium fluoroaluminate, 10 parts of sodium fluosilicate, 10 parts of calcium fluoride, 5 parts of potassium nitrate and 10 parts of potassium fluosilicate.

1) Preparation of an aluminium alloy melt

Melting: firstly, preheated Al-Si-Mg alloy A356 is added into a smelting furnace with a temperature rise in advance, and is heated and melted into molten aluminum within the range of 760 ℃.

Degassing and deslagging: after melting into molten aluminum, nitrogen (or argon) was introduced, and then a refining agent (0.3 wt% refining agent) was blown into the molten aluminum, with the period of 15 minutes.

Standing: and (4) standing the molten aluminum in the step S3 for 10 minutes, controlling the temperature to be 760 ℃, and fishing out slag impurities on the surface layer of the molten aluminum.

During the period, the chemical composition is measured and the hydrogen amount is estimated by taking a sample of the aluminum water which is standing:

estimating the hydrogen content by a density method, wherein the density requirement is as follows: greater than or equal to 2.65g/cm 3. The greater the density (closer to 2.7g/cm3), the lower the hydrogen content therein.

2) Purification treatment of master alloy

2.1) aluminum-strontium master alloy: purchased from nan tong ang shen metals materials ltd, ingredients: al-10Sr, Fe < 0.05.

Pretreatment: and (3) cleaning the oxide skin and the surface layer of the aluminum-strontium intermediate alloy by using a grinding wheel machine.

Ultrasonic cleaning: and putting the pretreated aluminum-strontium intermediate alloy into an ultrasonic cleaning tank for ultrasonic treatment.

Drying: and (3) putting the cleaned aluminum-strontium intermediate alloy into an oven furnace, and baking for 30-60 minutes at the temperature of 60-100 ℃.

Smelting: the aluminum-strontium intermediate alloy is put into a preheated crucible to be melted at 760-780 ℃.

Refining treatment: and refining after the aluminum-strontium intermediate alloy is melted. And introducing an Ar + graphite automatic degassing stirring rod to refine the molten high-purity aluminum. Blowing Ar into the molten aluminum for refining at the temperature of 730-750 ℃ for 5-10 minutes, wherein the blowing refining dose is 0.1-0.3 percent of the melt, and keeping the melt for 3-5 minutes, and no boiling bubbles can be formed on the upper surface of the molten aluminum in the refining process.

Removing the surface scum: and (3) putting 0.1-0.3% of deslagging agent into the mixture for 15-20 minutes, uniformly dispersing, and removing the scum on the surface.

Standing: standing for 8-15 minutes at 740-760 ℃ after slagging off.

2.2) refiner: refining treatment of Al-Ti-B intermediate alloy

Aluminum titanium boron intermediate alloy: from Nantong Angshen Metal materials Co., Ltd (composition and content: Ti: 5%, B: 1%, remainder: Al)

The aluminum titanium boron intermediate alloy as the refiner was treated in the same manner as described above.

3) Preparation of composite rare earth aluminum alloy

3.1) melting of high-purity rare-earth aluminum intermediate alloy

a) Preparation of high purity aluminum melt

Pretreatment: and (4) cleaning the oxide skin and the surface layer on the surface of the high-purity aluminum ingot by using a grinding wheel machine.

Ultrasonic cleaning: and (4) putting the pretreated high-purity aluminum ingot into a cleaning agent for ultrasonic treatment.

Drying: and (3) placing the high-purity aluminum ingot subjected to ultrasonic cleaning into a baking oven furnace, and baking for 30-60 minutes at the temperature of 60-100 ℃.

Smelting: and putting the dried high-purity aluminum into a preheated crucible, and heating and melting at the temperature of 760-800 ℃.

Refining treatment: and refining after the high-purity aluminum is melted. Specifically, the method comprises the following steps: and refining the molten high-purity aluminum by using an Ar + graphite automatic degassing stirring rod. Blowing Ar into the melt for refining at 740-760 ℃ for 5-10 min, wherein the refining dose is 0.1-0.3%, and keeping the temperature for 3-5 min. And standing for 10-20 minutes, and adding 0.1-0.3% of deslagging agent into the mixture to uniformly disperse the deslagging agent, and removing the surface scum.

Standing: standing for 8-15 minutes at 740-760 ℃ after slagging off.

b) Smelting of rare earth aluminum alloy:

adjusting the temperature of the high-purity aluminum obtained in the step a) to 780-820 ℃, heating to completely melt the high-purity aluminum, and adding rare earth aluminum-lanthanum alloy (purchased from Baotou rare earth research institute, components: al-10La, Fe < 0.05). Heating at 780-820 ℃ under the protection of argon atmosphere to completely melt the alloy.

Stirring and heat preservation: stirring the melted melt for 3-5 min to homogenize the melt, and maintaining the temperature of the melt at 760-780 ℃ for 10-20 min.

Refining treatment: the whole process is carried out under the protection of argon atmosphere, and refining treatment is carried out after the rare earth aluminum lanthanum alloy is melted. And introducing an Ar + graphite automatic degassing stirring rod to refine the molten graphite. Blowing Ar into the molten aluminum for refining at 760-780 ℃ for 5-10 minutes, wherein the blowing amount of the melt is 0.1-0.3%, and the melt is kept for 3-5 minutes, and no boiling bubbles can exist on the upper surface of the molten aluminum in the refining process. Removing scum on the surface of the melt: and (3) putting 0.1-0.3% of deslagging agent into the mixture for 15-20 minutes, uniformly dispersing, and removing the scum on the surface.

Standing: standing for 10-15 minutes at 720-730 ℃ after slag removal.

3.2) preparation of composite rare earth alloy

Respectively preparing an aluminum melt, a rare earth aluminum alloy, an aluminum strontium intermediate alloy and an aluminum titanium boron intermediate alloy, and then mixing and smelting the aluminum melt, the rare earth aluminum alloy, the aluminum strontium intermediate alloy and the aluminum titanium boron intermediate alloy to obtain the composite rare earth alloy.

In this embodiment, as the order of addition, the rare earth aluminum alloy is added to the aluminum melt, then the aluminum-strontium alloy is added, and finally the aluminum-titanium-boron alloy is added. The method comprises the following specific steps:

step 1, batching: weighing the obtained high-purity aluminum, the aluminum-titanium-boron intermediate alloy, the aluminum-strontium intermediate alloy and the rare earth aluminum alloy according to the required mass percentage, and then preheating.

Based on 100 parts of total weight, high-purity aluminum: 4.8 parts of aluminum-titanium-boron intermediate alloy: 0.2 part of aluminum-strontium intermediate alloy: 60 parts of rare earth aluminum alloy: 35 parts of (A).

Step 2, adding and melting rare earth aluminum alloy: for the aluminum melt, firstly heating the purified rare earth aluminum alloy to 780-820 ℃ to soften the rare earth aluminum alloy before melting, then controlling the overall temperature of the aluminum melt to 760-780 ℃, and adding the rare earth aluminum alloy into the aluminum melt for heat preservation.

The whole process adopts argon atmosphere protection to melt rare earth aluminum alloy.

And 3, after the rare earth aluminum alloy is completely melted, controlling the temperature to be 750-770 ℃, and stirring for 5-10 minutes.

The whole process adopts argon atmosphere for protection, and the stirring rod adopts graphite material and is preheated to 400-plus-500 ℃ before stirring.

That is, after the rare earth aluminum alloy is completely melted, the temperature is slightly lowered, and it is possible to prevent subsequent grain coarsening and the like due to overheating.

And 4, performing heat preservation treatment on the melted melt at 740-760 ℃ for 5-20 minutes. In this stage, an alloying reaction occurs.

Step 5, refining: after the heat preservation is finished, refining, degassing and deslagging are carried out. Blowing 0.3% of refining agent into the melt through argon, and controlling the ventilation time to be 3-8 minutes; then, the mixture was further added to 0.2% of a slag removing agent, stirred for 5 minutes, left to stand and the slag and impurities on the surface layer of the melt were removed. The whole process adopts argon atmosphere protection.

The aluminum melt was sampled before and during refining and its density was measured to estimate the hydrogen content. The measurement method used a density method (comparing with the theoretical value of aluminum of 2.70g/cm 3), and the closer the measured sample is to 2.7g/cm3, the lower the internal hydrogen content of aluminum. Normally, the concentration of the active carbon can not reach 2.7g/cm 3; the density test of the sample is about equal to 2.65g/cm3, namely, the vacuum treatment is needed in the process of estimating the hydrogen content, and if the hydrogen content is not qualified, the refining is further carried out, namely, the refining agent is repeatedly added, and the deslagging agent is refined again.

Step 6, standing: and standing the melt which is added with the rare earth aluminum alloy and refined for 3-5 minutes, and controlling the temperature at 740-760 ℃.

And 7, adding and melting an aluminum-strontium intermediate alloy: and (3) adding the refined aluminum-strontium intermediate alloy into the melt obtained in the step (6), and controlling the temperature to be 780-820 ℃ so that the aluminum-strontium intermediate alloy is completely melted. The whole process adopts argon atmosphere protection to melt the aluminum-strontium intermediate alloy.

And 8, after the aluminum-strontium intermediate alloy is melted, controlling the temperature to be 740-760 ℃, and stirring for 3-8 minutes to realize homogenization. The whole process adopts argon atmosphere for protection, the stirring rod adopts graphite material, and the stirring rod is preheated to 400-plus-500 ℃ before stirring.

And 9, performing heat preservation treatment at 725-750 ℃. The heat preservation time is controlled to be 15-30 minutes.

Step 10, refining, degassing and deslagging: after the heat preservation of the melt is finished, blowing argon gas into the melt, and then blowing 0.3% of refining agent into the aluminum-rare earth composite melt, wherein the ventilation time is controlled to be 5-10 minutes; adding 0.2% of slag skimming agent into the aluminum melt, stirring for 5 minutes and fishing out slag and impurities on the surface layer of the aluminum-rare earth composite melt. The whole process adopts argon atmosphere protection.

The aluminum melt was sampled before and during refining to determine the hydrogen content. (hydrogen content required: 2.65g/cm or more ³ (ii) a ) And (3) vacuumizing in the hydrogen measuring process, and further refining if the hydrogen content is unqualified, namely, repeatedly adding a refining agent and a deslagging agent for refining again.

Step 11, adding an aluminum-titanium-boron intermediate alloy: and (3) adding an aluminum-titanium-boron intermediate alloy into the melt treated in the step (10), heating to completely melt the aluminum-titanium-boron intermediate alloy, and uniformly stirring for 3-5 minutes to homogenize the aluminum-titanium-boron intermediate alloy.

Step 12, heat preservation: after stirring, the melt is kept at the temperature of 715-725 ℃ for 8-12 minutes.

Step 13, refining, degassing and deslagging: after the heat preservation of the melt is finished, blowing in argon gas, and then blowing in 0.3% of refining agent to the aluminum-rare earth composite melt, wherein the ventilation time is controlled to be 5-10 minutes; adding 0.2% of slag skimming agent into the aluminum melt, stirring for 5 minutes and fishing out slag and impurities on the surface layer of the aluminum-rare earth composite melt. The whole process adopts argon atmosphere protection.

The aluminum melt was sampled before and during refining to determine the hydrogen content. (hydrogen content required: 2.65g/cm or more) ³ (ii) a ) And (3) vacuumizing in the hydrogen measuring process, and if the hydrogen content is unqualified, further refining, namely repeatedly adding a refining agent and a deslagging agent, and refining again until the hydrogen content is qualified.

Step 14, casting: the mold was preheated at 300 ℃ to 400 ℃. And (3) controlling the temperature of the composite rare earth alloy melt obtained in the step (13) to be 715-725 ℃ for casting.

Preferably, during casting, the oxide on the surface layer of the aluminum-rare earth composite melt is filtered by a filter screen of glass fiber; and filtering the surface layer of the aluminum-rare earth composite melt before each casting, and then casting.

Preferably, the cooling control of the cast mould is that the aluminum rare earth composite melt cast into the mould is cooled in a water cooling mode, the solidification speed of the aluminum melt is controlled at 50-100 ℃/s in the cooling process, and the solidification mode is sequentially solidified.

The specific rare earth metals in the composite rare earth aluminum alloy are as follows: strontium: the amount by weight of titanium or titanium boron is not limited by the above examples, for example, the rare earth metals: strontium: the mass ratio of the titanium or the titanium boron can be 1 (0.1-1.2): (0.1-1.2).

4) Preparation of modified aluminum alloy biscuit

The method comprises the following steps of (1) preparing an aluminum alloy: compounding rare earth aluminum alloy: the mass ratio of the aluminum-titanium-boron intermediate alloy is 99.4: 0.4: 0.2 of the above aluminum-silicon-magnesium alloy, composite rare earth aluminum alloy, and aluminum-titanium-boron intermediate alloy.

Thereafter, melting was performed as follows.

Mixing: according to the proportion, when the temperature is controlled to be 740 +/-5 ℃ in the aluminum-silicon-magnesium alloy melt treated by the step 1), the composite rare earth aluminum alloy obtained by the step 3) is added firstly.

Stirring: stirring the melt which is added with the composite rare earth aluminum alloy and melted by a graphite stirrer, wherein uniform stirring is required in the stirring process, and the stirring is continuously carried out for 8 minutes;

preserving heat: after stirring, controlling the temperature at 735 ℃ and keeping the temperature for 20 minutes;

refining: after the heat preservation is finished, argon is introduced, then a slag remover is blown into the molten aluminum, and the ventilation time is controlled to be 15 minutes;

adding a refiner: adding 0.2% of aluminum-titanium-boron intermediate alloy into refined molten aluminum, and continuously refining after the intermediate alloy is melted and stirred;

and (3) heat preservation and standing: after refining is finished, after the molten aluminum flows into a heat preservation pool, when the temperature is controlled to be 710 +/-3 ℃, standing for 10 +/-2 minutes, and removing slag and impurities on the surface layer of the molten aluminum;

casting: and when the preheating mould is at the temperature of 250-400 ℃, casting the refined modified aluminum alloy with the temperature controlled at 700 +/-5 into the mould, and cooling to obtain the modified aluminum alloy biscuit. Wherein the thickness of the modified aluminum alloy biscuit is 30 mm.

5) Thermal treatment

Solution treatment: and (3) placing the modified aluminum alloy biscuit into a heating furnace, heating to 540 ℃ at the heating rate of 2 ℃/min, and preserving the heat for 120 min.

And (3) quenching treatment, namely adding the modified aluminum alloy biscuit subjected to the solution treatment into a circulating water bath at the temperature of 65 ℃ for quenching for 3 min.

And (3) aging treatment, namely preserving the heat of the modified aluminum alloy biscuit subjected to quenching treatment at 150 ℃ for 120min, then cooling to 110 ℃ at a cooling rate of 2 ℃/min, preserving the heat for 30min, and then naturally cooling to room temperature to obtain the high-strength composite modified aluminum alloy product.

FIG. 1 is a photograph of a high strength composite modified aluminum alloy article, a wheel hub, made in example 1. Fig. 2 is a metallographic image of the rib portion of the hub shown in fig. 1, wherein (a) is a low-power image, (b) is a medium-power image, and (c) is a high-power image. As can be seen from FIG. 2, the metallographic structure of the modified and heat-treated aluminum alloy of this example was further increased as compared with the rounded spherical α -Al phase, and the primary α -Al phase and dendrites were substantially not observed. That is, the grains are further homogenized, and the microstructure is more uniform. In addition, the spherical alpha-Al phase is uniformly distributed at the grain boundary.

The mechanical properties of the A356 aluminum alloy (referred to as "before modification"), the biscuit (referred to as "modified alloy 1") after modification, and the article after heat treatment (referred to as "example 1") were evaluated. The evaluation results are shown in table 1 below.

Table 1 evaluation results of mechanical properties of high-strength composite modified aluminum alloy articles of example 1

Mechanical Properties	Before modification	Modified alloy 1	Example 1
				Tensile strength (MPa)	130±3.5	220±5	320±5
Yield strength (MPa)	65±5.5	108±6	220±5
				Elongation (%)	3±0.25	20±0.6	13±0.35

As is clear from table 1, the strength of the heat-treated steel sheet of example 1 was greatly improved even when the heat treatment was performed. On the basis of combining with the heat treatment, the yield strength and the tensile strength of the aluminum alloy ingot are greatly improved (compared with the aluminum alloy ingot which is not modified and is not subjected to the heat treatment, the yield strength and the tensile strength are respectively increased by nearly 4 times and nearly 3 times), meanwhile, the higher-level elongation is kept (compared with the aluminum alloy ingot which is not treated, the elongation is increased by more than 4 times), and the comprehensive mechanical property is greatly improved.

Example 2

In this example, the same as example 1 was used except that a combination of a rare earth aluminum alloy, an aluminum strontium master alloy, aluminum titanium or an aluminum titanium boron master alloy was used as a modifier as compared with example 1.

In the following, only the parts involved in the processing of the modified aluminium alloy melt are described as follows:

4) preparation of modified aluminum alloy biscuit

The method comprises the following steps of (1) preparing an aluminum alloy: rare earth aluminum alloy (purification treatment of rare earth aluminum alloy same as in example 1): aluminum-strontium alloy: the mass ratio of the aluminum-titanium-boron intermediate alloy is 99.4: 0.2: 0.2: 0.2 of the above aluminum-silicon-magnesium alloy, rare earth aluminum alloy, aluminum-strontium intermediate alloy, and aluminum-titanium-boron intermediate alloy.

Thereafter, melting was performed as follows.

Mixing: according to the proportion, when the temperature of the aluminum-silicon-magnesium alloy melt treated in the step 1) is controlled to be 740 +/-5 ℃, the rare earth aluminum alloy is firstly added.

Stirring: stirring the melt which is added with the rare earth aluminum alloy and melted by a graphite stirrer, wherein uniform stirring is required in the stirring process, and the stirring is continuously carried out for 8 minutes;

adding an aluminum-strontium intermediate alloy: adding 0.2% of aluminum-strontium intermediate alloy into refined molten aluminum, and continuously refining after the aluminum-strontium intermediate alloy is melted and stirred;

homogenizing: after the aluminum-strontium intermediate alloy is completely melted, controlling the temperature to be 740-760 ℃, and stirring for 3-8 minutes to realize homogenization;

and (3) heat preservation: then, carrying out heat preservation treatment at 725-750 ℃, wherein the heat preservation time is controlled to be 15-30 minutes;

and (3) heat preservation and standing: after refining is finished, after the molten aluminum flows into a heat-preserving tank, when the temperature is controlled at 710 +/-3 ℃, standing for 10 +/-2 minutes, and removing slag and impurities on the surface layer of the molten aluminum;

casting: and when the mold is preheated to the temperature of 250-400 ℃, casting the refined modified aluminum alloy with the temperature controlled at 700 +/-5 into the mold, and cooling to obtain the modified aluminum alloy biscuit.

The metallographic structure image of the product obtained in this example was similar to that of example 1 and will not be described in detail here.

Table 2 evaluation results of mechanical properties of high-strength composite modified aluminum alloy articles of example 2

Mechanical Properties	Before modification	Modified alloy 2	Example 2
				Tensile strength (MPa)	130±3.5	200±5.5	300±5
Yield strength (MPa)	65±5.5	95±4.2	235±5
				Elongation (%)	3±0.25	16.6±0.35	8.4±0.35

The modified alloy 2 is a modified green body, and is not subjected to heat treatment.

As is clear from table 2, similar results to those of example 1 were obtained by the heat treatment of example 2.

Meanwhile, compared with the embodiment 2, the rare earth aluminum alloy and the aluminum-strontium intermediate alloy are firstly smelted to prepare the composite rare earth aluminum alloy, and the composite modified aluminum alloy product obtained by modifying the composite rare earth aluminum alloy has higher comprehensive mechanical properties.

Example 3

In this example, the same as in example 1 was repeated except that ZL111 was used in place of A356.

The specific preparation is as in example 1, and a detailed description thereof is omitted.

Further, the mechanical properties of ZL111 aluminum alloy (referred to as "before modification"), the biscuit (referred to as "modified alloy 3") after modification, and the article after heat treatment (referred to as "example 3") were evaluated. The evaluation results are shown in table 3 below.

Table 3 evaluation results of mechanical properties of high strength composite modified aluminum alloy article of example 3

Mechanical Properties	Before modification	Modified alloy 3	Example 3
				Tensile strength (MPa)	160±4.5	240±5	350±5
Yield strength (MPa)	75±4.5	120±5	240±5
				Elongation (%)	3±0.25	15±0.5	10±0.35

As is clear from table 3, similar results to those of examples 1 and 2 were obtained by the heat treatment of example 3. That is, the preparation process of the invention is also suitable for eutectic aluminum alloy, and can obtain better strength and higher toughness.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. The preparation method of the high-strength composite modified aluminum alloy product is characterized by comprising the following steps of:

step S1, providing an aluminum alloy melt;

step S2, providing a modifier;

the modifier is a combination of a composite rare earth aluminum alloy and an aluminum-titanium intermediate alloy or a combination of a composite rare earth aluminum alloy and an aluminum-titanium-boron intermediate alloy, the composite rare earth aluminum alloy contains strontium, titanium or titanium-boron and rare earth metals, and the rare earth metals in the composite rare earth aluminum alloy are as follows: strontium: the mass ratio of the total amount of titanium or titanium boron is 1: (0.1-1.2): (0.1-1.2);

the rare earth metal in the composite rare earth aluminum alloy is any one or more of lanthanum, cerium and yttrium;

the preparation of the composite rare earth aluminum alloy comprises the following steps:

step S211, providing an aluminum melt;

step S213, sequentially adding the rare earth intermediate aluminum alloy, the aluminum-strontium intermediate alloy and the aluminum-titanium or aluminum-titanium-boron intermediate alloy into the aluminum melt in an inert gas atmosphere, and smelting to obtain the composite rare earth aluminum alloy;

step S3, adding the modifier into the aluminum alloy melt and smelting to obtain a modified aluminum alloy melt under an inert gas atmosphere, wherein the modifier accounts for 0.4-0.6wt% of the total amount of the modified aluminum alloy melt;

quenching treatment, namely adding the modified aluminum alloy biscuit subjected to the solution treatment into a water bath at the temperature of 60-70 ℃ for quenching for 2-4 min;

and (3) aging treatment, namely preserving the modified aluminum alloy biscuit subjected to quenching treatment at the temperature of 150-165 ℃ for 280min, then cooling to the temperature of 110-130 ℃ and preserving the heat for 30-120min, and then naturally cooling to room temperature to obtain the high-strength composite modified aluminum alloy part.

2. The method for preparing a composite material according to claim 1, wherein the step S1 includes:

providing an aluminum alloy mother ingot;

3. The method for preparing a composite material according to claim 1, wherein the step S3 includes:

step S320, adding the aluminum-titanium or aluminum-titanium-boron intermediate alloy into the fourth uniformly mixed melt and continuously smelting to obtain the modified aluminum alloy melt.

4. The method as claimed in claim 1, wherein in step S5, the temperature increase rate in the solution treatment is controlled to be 1.5-3 ℃/min, and the temperature holding time is controlled to be 180 min.

5. The production method according to claim 1, wherein the solution treatment, the quenching treatment, and the aging treatment are continuous treatments,

and the water bath is a circulating water bath, and after the quenching treatment, the temperature of the modified aluminum alloy biscuit is kept above 55 ℃ before the aging treatment.

6. The method as claimed in claim 1, wherein the aging treatment stage is performed at a temperature decreasing rate of 2-5 ℃/min from 150-165 ℃ to 110-130 ℃.

7. A high-strength composite modified aluminum alloy product, which is prepared by the preparation method according to any one of claims 1 to 6, and has a tensile strength of 300MPa or more, a yield strength of 230MPa or more, and an elongation of 6% or more.