KR20240029059A - High-strength composite modified aluminum alloy parts and manufacturing method thereof - Google Patents

Abstract

The present invention provides a high-strength composite modified aluminum alloy part and a method for manufacturing the same. Here, the manufacturing method includes step S1 of providing an aluminum alloy melt; Step S2 providing a modifier; Step S3 to obtain a modified aluminum alloy melt by adding a modifier to the aluminum alloy melt and melting it under an inert gas atmosphere; Step S4, performing casting using the modified aluminum alloy melt to obtain a cast aluminum alloy blank; and step S5 of performing heat treatment on the modified aluminum alloy blank, where the heat treatment includes the following steps: heating the aluminum alloy blank to 530°C-550°C and maintaining the temperature for 100-300 minutes. embodied processing; Water quenching treatment, in which the aluminum alloy blank after solution treatment is placed in a water bath with a temperature of 60℃-70℃ and water quenching is performed for 2-4 minutes; After the solution treatment, the aluminum alloy blank is placed in a water bath at a temperature of 60°C-70°C, and water quenching is performed; After water quenching treatment, the aluminum alloy blank is subjected to aging treatment of keeping at 150℃-165℃ for 120-280 minutes, then cooling to 110℃-130℃, holding the temperature for 30-120 minutes, and then natural cooling to room temperature to achieve high strength. Obtain composite modified aluminum alloy parts.

Description

High-strength composite modified aluminum alloy parts and manufacturing method thereof

The present invention relates to the field of alloy materials and manufacturing technology, particularly to high-strength composite modified aluminum alloy parts and methods for manufacturing the same.

Aluminum alloy is the most widely used non-ferrous metal structural material in industry and has been widely used in aviation, aerospace, automobile, machinery manufacturing, shipbuilding and chemical industries. Cast aluminum alloy has properties such as casting fluidity, good airtightness, small shrinkage and small thermal crack tendency, and has become the preferred material for lightweight automobile wheel hubs.

However, as people's requirements for aluminum alloy become more and more high, aluminum alloy must not only maintain its original lightweight properties, but also have a certain strength, especially in automobile parts and industrial production. For large cast aluminum alloy parts, high strength and medium toughness are required to solve mechanical property problems.

For this reason, a process of reforming the aluminum alloy with a modifier such as an aluminum-strontium alloy and refining the aluminum alloy with a refining agent has been proposed. However, ideal strength and plasticity still cannot be achieved with existing reforming methods. Based on this, research on heat treatment of cast aluminum alloy is conducted. However, because the composition of aluminum alloy parts is different, the heat treatment steps are also different. Current heat treatment requires high temperatures, consumes a lot of energy, takes a long time, and increases processing costs. Additionally, since the treatment is carried out directly at high temperatures, it is not conducive to phase interconversion and leads to uniform precipitation and, consequently, uneven mechanical properties of the alloy.

Therefore, a preparation process that can further improve the mechanical strength of aluminum alloy parts is urgently needed.

From this perspective, the present invention provides a high-strength composite modified aluminum alloy part and a manufacturing method thereof that can further improve the mechanical strength of the aluminum alloy.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

According to one embodiment of the present invention, a method for manufacturing a high-strength composite modified aluminum alloy part is provided including the following steps:

Step S1, providing an aluminum alloy melt;

Step S2, providing a modifier;

The modifier is a combination of a rare earth aluminum alloy, an aluminum-strontium master alloy, and an aluminum-titanium or aluminum-titanium-boron master alloy, or

The modifier is a combination of a composite rare earth aluminum alloy and an aluminum-titanium or aluminum-titanium-boron master alloy, and the composite rare earth aluminum alloy includes strontium, titanium or titanium boron and a rare earth metal,

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

Step S3, adding a modifier to the aluminum alloy melt under an inert gas atmosphere and melting it to obtain a modified aluminum alloy melt;

Step S4, performing casting using the modified aluminum alloy melt to obtain a modified aluminum alloy blank; and

Step S5, heat treatment is performed on the modified aluminum alloy blank, and the heat treatment includes,

solution heat treatment in which the modified aluminum alloy blank is heated to 530-550° C. and held for 100-300 minutes;

Water quenching treatment in which the modified aluminum alloy blank after the solution treatment is placed in a water bath at 60-70°C and quenched with water for 2-4 minutes; and

After the water quenching treatment, the modified aluminum alloy blank is maintained at 150-165 ℃ for 120-280 minutes, then further cooled to 110-130 ℃, maintained for 30-120 minutes, and then naturally cooled to room temperature to produce high-strength composite modified alloy parts. Aging processing to obtain; includes.

Additionally, the S1 phase includes:

providing an aluminum alloy ingot;

Removing the oxide scale layer on the surface of the aluminum alloy ingot, washing and drying; and

It includes the step of melting the dried aluminum alloy ingot and removing the purification and slag to obtain an aluminum alloy melt,

The composition of the aluminum alloy ingot is hypoeutectic aluminum alloy or eutectic aluminum alloy.

According to some embodiments of the present invention, the modifier is a combination of rare earth aluminum alloy, aluminum-strontium master alloy, aluminum-titanium or aluminum-titanium-boron master alloy,

The aluminum-strontium master alloy and aluminum-titanium or aluminum-titanium-boron master alloy are added at intervals,

The rare earth aluminum alloy is added first, added together with the first added components, or added at an interval between the addition of the aluminum-strontium master alloy and the addition of the aluminum-titanium or aluminum-titanium-boron master alloy.

Additionally, step S3 includes:

Step S301, adding the rare earth aluminum alloy to the aluminum alloy melt and melting it to obtain a first homogeneous mixed melt;

Step S302, adding the aluminum-strontium master alloy to the first homogeneous mixed melt and continuously melting it to obtain a second homogeneous mixed melt; and

Step S303 is a step of adding the aluminum-titanium or aluminum-titanium-boron master alloy to the second homogeneous melt mixture and continuously melting it to obtain a modified aluminum alloy.

According to another embodiment of the present invention, the modifier is a combination of a composite rare earth aluminum alloy and an aluminum-titanium or aluminum-titanium-boron master alloy, and step S3 is,

Step S310, adding the composite rare earth aluminum alloy to the aluminum alloy melt and melting it to obtain a fourth homogeneous mixed melt; and

Step S320 is a step of adding the aluminum-titanium or aluminum-titanium-boron master alloy to the fourth homogeneous mixed melt and continuously melting it to obtain a modified aluminum alloy.

Additionally, the production of the composite rare earth aluminum alloy includes:

Step S211, providing the aluminum melt;

Step S212, providing an aluminum-strontium master alloy, an aluminum-titanium or aluminum-titanium-boron master alloy, and a rare earth aluminum master alloy, and the rare earth metal contained in the rare earth aluminum master alloy is selected from lanthanum, cerium, and yttrium. It is one or more types; and

In step S213, under an inert gas atmosphere, the rare earth aluminum alloy, aluminum-strontium master alloy, aluminum-titanium or aluminum-titanium-boron master alloy is sequentially added to the aluminum melt and melted to obtain a composite rare earth aluminum alloy.

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

Additionally, in step S5, the temperature increase rate of the solution treatment is adjusted to 1.5-3 °C/min, and the holding time is adjusted to within 120-180 minutes.

Additionally, solution treatment, water quenching treatment and aging treatment are continuous treatments;

The water bath is a circulating water bath, and the temperature of the cast aluminum alloy blank is maintained above 55°C after the water quenching treatment and before the aging treatment is performed.

Additionally, the aging treatment step cools the temperature from 150-165°C to 110-130°C at a cooling rate of 2-5°C/min.

According to an embodiment of the second aspect of the present invention, a high-strength composite-modified aluminum alloy part is provided, wherein the high-strength composite-modified aluminum alloy part is obtained by the manufacturing method according to the above-described embodiment, and the high-strength composite-modified aluminum alloy part is provided. The tensile strength of alloy parts is more than 300 MPa, the yield strength is more than 230 MPa, and the elongation is more than 6%.

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

According to the manufacturing method of the high-strength composite modified aluminum alloy part of the embodiment of the present invention, the aluminum alloy is modified by introducing rare earth metal, and the casting is processed in combination with a specific heat treatment process, so that the mechanical strength of the composite modified aluminum alloy part is greatly improved. It can be improved to meet the needs of aviation, aerospace and automotive fields, and the toughness of composite modified aluminum alloy parts is simultaneously improved and the occurrence of brittle cracks is reduced.

Figure 1 is a photograph of a high-strength composite modified aluminum alloy part, that is, a wheel hub, manufactured in Example 1.
FIG. 2 is a metal structure image of the rib portion of the wheel hub shown in FIG. 1, where (a) is a low magnification image, (b) is a medium magnification image, and (c) is a high magnification image.

In order to make the objectives, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention are clearly and completely explained below with reference to the embodiments of the present invention. Clearly, the described embodiments are some but not all embodiments of the invention. All other embodiments attainable by a person skilled in the art based on the described embodiments of the present invention fall within the protection scope of the present invention.

Unless otherwise defined, technical or scientific terms used in the present invention have common meanings to those skilled in the art to which the present invention pertains. As used herein, “first,” “second,” and similar words do not indicate order, quantity, or importance, and are used only to distinguish different elements. Likewise, words such as "which" or "one" do not indicate a quantitative limitation, but rather indicate that there is at least one.

First, a method for manufacturing a high-strength composite modified aluminum alloy part according to an embodiment of the present invention will be described in detail below.

The method for manufacturing a high-strength composite modified aluminum alloy part according to an embodiment of the present invention includes the following steps:

Step S1: Prepare aluminum alloy melt.

That is, first, an aluminum alloy melt is prepared.

Here, it should be noted that aluminum alloy melts can be produced by directly heating and melting commercially available high-purity aluminum alloy ingots, or the aluminum alloy ingots can be further refined. For example, purification processing may include the following steps:

Step S11: Prepare an aluminum alloy ingot.

Step S12: Remove the oxide scale layer on the surface of the aluminum alloy ingot.

Step S13: Wash and dry the aluminum alloy ingot from which the oxide scale layer has been removed.

Step S14: Melt the dried aluminum alloy ingot to obtain the initial melt.

Step S15: Purify the initial melt to obtain an aluminum alloy melt.

That is, in the case of an aluminum alloy ingot, the oxide scale layer on the surface of the aluminum alloy ingot is first removed, then the aluminum alloy ingot is washed to remove surface slag, dried, and then melted to purify the melt. The specific purification process will be described in detail later.

After the above purification treatment, unwanted impurities such as Fe and oxides can be removed from the aluminum alloy ingot. It helps to further improve the reforming and refining of rare earth alloys.

It should be further noted that iron and its oxides can be removed, for example, by adding manganese or aluminum-manganese alloys to form surface slag.

The matrix to be modified, ie the aluminum alloy melt, can be, for example, an aluminum-magnesium alloy, an aluminum-silicon alloy and an aluminum-silicon-magnesium alloy. This is not particularly limited in the present invention.

Step 2: Prepare the modifier.

The modifier is a combination of rare earth aluminum alloy, aluminum-strontium master alloy, aluminum-titanium or aluminum-titanium-boron master alloy, or a combination of composite rare earth aluminum alloy, aluminum-titanium or aluminum-titanium-boron master alloy.

Complex rare earth aluminum alloys contain strontium, titanium or titanium boron, rare earth metals.

The rare earth metal in rare earth aluminum alloy and composite rare earth aluminum alloy is one or more of lanthanum, cerium, and yttrium.

That is, there are two implementation methods as follows:

Implementation method 1

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

The aluminum-strontium master alloy is the modifier and the aluminum-titanium master alloy or aluminum-titanium-boron master alloy is the refiner. That is, existing modifiers and purifiers can be used.

Additionally, commercially available materials may be used as the modifier and/or purifier, or the modifier and/or purifier may be prepared by weighing the corresponding metals strontium, titanium, titanium, and boron, and may be dissolved in aluminum melt to form a uniform solution. forms an alloy.

In addition, in addition to existing modifiers and purifiers, rare earth aluminum alloys are additionally introduced to overcome limitations in mechanical properties due to "poisoning" reactions, which are side effects or limitations caused by reactions between modifiers and purifiers. As a rare earth metal in rare earth aluminum alloy, considering strontium in the modifier and titanium and boron in the purifier, group IIIB elements whose electronic structure is between strontium and titanium and boron can be selected. Considering the stability and amount of resources of rare earth metals, it is desirable to use at least one of lanthanum and cerium among yttrium and lanthanide metals. For example, one or more of commercially available Al-10Ce, Al-20Ce, Al-20La, Al-10La, Al-20Y, and Al-10Y can be used as the rare earth aluminum alloy.

Rare earth aluminum alloys can also be prepared, for example, by:

Add rare earth metal or master alloy containing rare earth metal to the aluminum melt in an inert atmosphere and stir while heating until completely melted;

After complete melting, maintain temperature for 10-20 minutes to ensure uniform melt;

The homogenized melt is purified.

To obtain rare earth aluminum alloy, it is purified, left for a certain period of time, and then cast.

In the case of aluminum melt, commercially available high-purity aluminum ingots can be used, and the corresponding treatment can be performed on the high-purity aluminum ingot by referring to the purification treatment of aluminum alloy ingots. Details are not described in this specification.

In addition, in the case of commercially available aluminum-strontium master alloy, aluminum-titanium master alloy, aluminum-titanium-boron master alloy, and rare earth aluminum alloy, scale removal, ultrasonic cleaning, and purification treatment can be performed sequentially, respectively. In this way, further removal of unwanted impurities and oxides helps improve the purification and reforming of complex rare earth alloys as products.

Implementation method 2:

This modifier is a combination of a composite rare earth aluminum alloy and an aluminum-titanium or aluminum-titanium-boron master alloy.

A composite rare earth aluminum alloy can be produced by melting and refining the rare earth aluminum alloy, aluminum-strontium master alloy, aluminum-titanium or aluminum-titanium-boron master alloy, and aluminum melt.

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

Step S211 is a step of providing aluminum melt.

Step S212, providing an aluminum-strontium master alloy, an aluminum-titanium or aluminum-titanium-boron master alloy, and a rare earth aluminum master alloy, and the rare earth metal contained in the rare earth aluminum master alloy is selected from lanthanum, cerium, and yttrium. There is more than one type.

Step S213 is a step of obtaining a composite rare earth aluminum alloy by sequentially adding and melting the rare earth aluminum alloy, aluminum-strontium master alloy, aluminum-titanium or aluminum-titanium-boron master alloy to the aluminum melt under an inert gas atmosphere.

The aluminum-strontium master alloy and the aluminum-titanium or aluminum-titanium-boron master alloy are added at intervals, and the rare earth aluminum alloy is added before the aluminum-strontium master alloy and the aluminum-titanium or aluminum-titanium-boron master alloy, or at the beginning. It is added together with the added components, or is added at an interval between the addition of the aluminum-strontium master alloy and the addition of the aluminum-titanium or aluminum-titanium-boron master alloy.

It is preferable to sequentially add the rare earth aluminum alloy, aluminum-strontium master alloy, aluminum-titanium or aluminum-titanium-boron master alloy to the aluminum melt at intervals.

Step S3, a modifier is added to the aluminum alloy melt in an inert gas atmosphere and melted to obtain a modified aluminum alloy melt.

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

According to the manufacturing method of the embodiment of the present invention, the rare earth metal is introduced into the reforming agent, which greatly overcomes the mutual poisoning effect between the reforming agent and the refining agent, can increase the addition amount of the reforming agent and the refining agent, and achieves the effects of reforming and refining at the same time. It can be improved.

For the above two combinations of modifiers, the following melting is performed respectively.

Regarding the modifier being a combination of rare earth aluminum alloy, aluminum-strontium master alloy, aluminum-titanium or aluminum-titanium-boron master alloy, it is as follows:

Specifically, for each rare earth aluminum alloy, aluminum-strontium master alloy, aluminum-titanium or aluminum-titanium-boron master alloy and pretreatment thereof, step S2 may be referred to.

In this combination, the aluminum-strontium master alloy and the aluminum-titanium or aluminum-titanium-boron master alloy are added at intervals, the rare earth aluminum alloy is added first, added together with the components added first, or the aluminum-strontium master alloy is added first. It is added at intervals between adding the alloy and adding the aluminum-titanium or aluminum-titanium-boron master alloy.

More preferably, step S3 may specifically include the following steps:

Step S301, the rare earth aluminum alloy is added to the aluminum alloy melt and melted to obtain a first homogeneous mixed melt.

Step S302, the aluminum-strontium master alloy is added to the first homogeneous mixed melt and continues to melt to obtain a second homogeneous mixed melt.

Step S303, the aluminum-titanium or aluminum-titanium-boron master alloy is added to the second homogeneous melt mixture and continuously melted to obtain a modified aluminum alloy.

In other words, melting is performed by adding the rare earth aluminum alloy first, and based on this, aluminum-strontium master alloy as a modifier and aluminum-titanium master alloy or aluminum-titanium-boron mother alloy as a refiner are sequentially added at intervals to produce strontium and boron. The poisoning effect of can be well solved and a modified aluminum alloy with more purity, uniformity and better mechanical properties is obtained.

Additionally, with respect to the modifier being a combination of a composite rare earth aluminum alloy and an aluminum-titanium or aluminum-titanium-boron master alloy, step S3 includes:

Step S310, the composite rare earth aluminum alloy is added to the aluminum alloy melt and melted to obtain a fourth homogeneous mixed melt.

Step S320, aluminum-titanium or aluminum-titanium-boron master alloy is added to the fourth homogeneous mixed melt and continued to melt to obtain a modified aluminum alloy.

That is, when the rare earth aluminum alloy, modifier, refining agent and aluminum are pre-melted to obtain the composite rare earth aluminum alloy, the composite rare earth aluminum alloy is obtained by adding the rare earth aluminum alloy, modifier, refining agent and aluminum to the aluminum melt at once. can be manufactured. Of course, taking into account that abnormal growth of crystal grains tends to occur during high temperature melting, which is not conducive to improving the mechanical properties of composite rare earth aluminum alloy. Preferably, when the composite rare earth aluminum alloy is completely melted and mixed with the aluminum alloy, a purifying agent, i.e. aluminum-titanium master alloy or aluminum-titanium-boron master alloy, is further added to control grain growth.

As a modifier, the additional amount of modifier is appropriately designed according to the usage requirements and various active ingredient contents of the master alloy. For example, when a composite rare earth alloy (mass ratio of the total amount of rare earth elements contained: strontium:titanium or titanium and boron = 1: (0.1-1.2): (0.1-1.2)) is introduced, the modifier is used to It is desirable to account for 0.4-0.6 wt% of the total amount.

In addition, purification in any of the above steps, that is, purification in the process of refining the aluminum melt, purification in the process of producing the rare earth aluminum alloy, and purification of each melt of the composite rare earth aluminum alloy, may be performed in the following manner. You can:

Use inert gas to blow the purifier and hold for 3-10 minutes, then add slag remover and stir for 5-10 minutes to remove surface slag.

Additionally, the amount of refiner added accounts for 0.1-0.3% of the added melt mass, and the added amount of slag remover accounts for 0.1-0.3% of the added melt mass.

The components of the tablet by mass are as follows:

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

The components of the slag remover expressed by mass are as follows:

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

Additionally, the hydrogen content of the melt can be monitored to determine whether purification should continue. In the present invention, the hydrogen content is estimated by testing the density of the melt. The closer the density of the melt is to the theoretical density of the melt (density varies slightly depending on the differences in components contained in the alloy, approximately 2.7 g/cm ³ ). This indicates that the hydrogen content in the melt is low. For example, if the density of the melt is less than 2.65 g/cm ³ , purification treatment may be performed, and if the density of the melt is 2.65 g/cm ³ or more, purification treatment may not be performed or the purification treatment may be terminated.

Step S4, performing casting on the modified aluminum alloy melt to obtain a cast aluminum alloy blank.

That is, the modified aluminum alloy melt obtained after melting is cast in a mold to obtain a cast aluminum alloy blank.

For specific casting processes, conventional casting processes may be used. A detailed description of this is omitted here.

Step S5, heat treatment is performed on the aluminum alloy blank.

That is, in order to further improve the mechanical strength of the aluminum alloy blank after obtaining it by casting, the present inventor developed a heat treatment process based on repeated research.

Specifically, heat treatment includes:

Solution heat treatment, in which the aluminum alloy blank is heated to 530-550 ° C and held for 100-300 minutes;

Water quenching treatment, in which the aluminum alloy blank after solution treatment is placed in a water bath at 60-70℃ and quenched with water for 2-4 minutes; and

After water quenching, the aluminum alloy blank is kept at 150-160 ℃ for 120-280 minutes, then cooled to 110-130 ℃, maintained for 30-120 minutes, and then subjected to aging treatment by cooling to natural room temperature, resulting in high-strength composite modified aluminum. Obtain alloy parts.

That is, the aluminum alloy blank continuously undergoes solution heat treatment, water quenching treatment, and aging treatment.

The solution heat treatment is designed to eliminate stresses caused by the cooling rate of the casting during crystal solidification, such as the structure of the casting (e.g. uneven wall thickness and thick transition), thereby improving the mechanical strength and hardness of the alloy. The metal structure can be improved and the structure can be uniform by eliminating grain boundaries and component separation.

In addition, the above water quenching treatment is designed to cool the casting quickly so that the reinforcing ingredients are dissolved into the alloy as much as possible and then fixed and stored at room temperature.

In addition, by designing the above aging treatment to increase the temperature and extend the time, the atoms in the supersaturated solid solution lattice are recombined and a solute atom-rich region (called G-PI region) is created, and then the G-PI region disappears. The atoms of the second phase are separated according to certain rules, the G-PII region is created, and a metastable second phase (transition phase) is created. By combining a large number of G-PII regions and a small amount of metastable phase, the metastable phase is converted to a stable phase and the second phase particles are aggregated.

In addition, according to the manufacturing method of the present invention, high temperature aging is adopted first, so that more phase transition occurs in the β' region and β'' region, thereby ensuring high strength.

Preferably, the heating rate of solution treatment is controlled to 1.5-3°C/min, and the holding time is controlled to within 120-180 minutes. By controlling the heating rate and holding time of solution treatment, the rose-shaped α-Al phase and the more rounded spherical α-Al phase can be further increased, the primary α-Al phase can be purified, and the number of dendrites can be reduced. there is.

Additionally, solution treatment, water quenching treatment and aging treatment are continuous treatments, and the water tank is a circulating water tank. After water quenching treatment and before performing aging treatment, the temperature of the cast aluminum alloy blank is maintained above 55℃. Continuous processing not only improves production efficiency, but also prevents unnecessary defects due to process interruption. Additionally, the minimum temperature is controlled during the period to prevent defects due to rapid cooling.

Additionally, in the aging treatment step, the temperature is cooled from 150-65 ℃ to 110-130 ℃ at a cooling rate of 2-5 ℃/min. By controlling the cooling rate in the aging treatment step, the introduction of defects can be greatly reduced, which helps improve the mechanical strength of aluminum alloy and maintain a high level of mechanical strength. The manufacturing method according to the present invention will be described in detail below using specific examples.

Example 1

Aluminum alloy: Aluminum-silicon-magnesium alloy (A356) (purchased by: Shandong Weiqiao Aluminum Industry) is used.

High-purity aluminum ingot (purchased from China Aluminum Corporation, composition: Al (99.99%), Fe<0.1%, impurities<0.05%)

Purification agent:

Ingredients: 15 parts potassium chloride, 20 parts sodium chloride, 10 parts CaF ₂ , 20 parts Na ₂ CO ₃ , 10 parts Na ₂ SO ₄ , 15 parts Na ₃ AlF ₆ , 10 parts C ₂ Cl ₆ .

Slag remover:

Ingredients: 25 parts sodium chloride, 25 parts potassium chloride, 5 parts sodium carbonate, 5 parts sodium sulfate, 5 parts sodium aluminum fluoride, 10 parts sodium fluorosilicate, 10 parts calcium fluoride, 5 parts potassium nitrate, 10 parts potassium fluorosilicate.

1) Preparation of aluminum alloy melt

Melting: Put the preheated aluminum-silicon-magnesium alloy A356 into a preheated melting furnace and heat it within the range of 760 ℃ to melt it with aluminum water.

Degassing and slag removal: After aluminum is dissolved in water, nitrogen (or argon) is injected into aluminum water, then purifier (0.3 wt% purifier) is blown into aluminum water, and ventilation time is controlled to 15 minutes.

Standing: Leave the aluminum water in S3 for 10 minutes, control the temperature to 760℃, and clean the slag impurities on the surface of the aluminum water.

During this period, the aluminum water is collected and sampled to determine its chemical composition and estimate the amount of hydrogen:

The hydrogen content of stagnant aluminum water is estimated using the density method, and the density should be not less than 2.65 g/cm ³ . The higher the density (closer to 2.7 g/cm ³ ), the lower the hydrogen content is considered.

2) Refining treatment of master alloy

2.1) Aluminum-strontium master alloy: purchased from Nantong Angshen Metal Materials Co., Ltd., composition: Al-10Sr, Fe<0.05.

Pretreatment: Use a grinder to clean the oxide scale and surface layer of the aluminum-strontium master alloy.

Ultrasonic cleaning: The pretreated aluminum-strontium master alloy is placed in an ultrasonic cleaning tank and ultrasonicated.

Drying: Place the cleaned aluminum-strontium master alloy in an oven and bake at 60-100°C for 30-60 minutes.

Melting: Place the aluminum-strontium master alloy in a preheated crucible and melt at 760-780°C.

Refining treatment: After melting the aluminum-strontium master alloy, purification treatment is performed. Purification is performed by adding an Ar+graphite automatic degassing stirring rod to the molten high-purity aluminum. The purifier is injected by adding Ar at 730-750°C for 5-10 minutes. The amount of purifier injected is 0.1-0.3% of the melt, and this process is maintained for 3-5 minutes. During the purification process, there should be no boiling bubbles on the upper surface of the aluminum liquid.

Surface slag removal: After 15-20 minutes, add slag remover in an amount equivalent to 0.1-0.3% of the melt and spread evenly to remove surface slag.

Standing: After removing the slag, the aluminum melt is left at 740-760°C for 8-15 minutes.

2.2) Refining agent: Refining treatment of aluminum-titanium-boron master alloy

Aluminum-titanium-boron master alloy: purchased from Nantong Angshen Metal Materials Co., Ltd. (Composition and content: Ti: 5%, B: 1%, remainder: Al)

For the aluminum-titanium-boron master alloy used as a refining agent, the same treatment is performed with reference to the above description.

3) Manufacturing of composite rare earth aluminum alloy

3.1) Melting of high-purity rare earth aluminum master alloy

a) Preparation of high purity aluminum melt

Pretreatment: Use a grinder to clean the scale and surface layer on the surface of the high-purity aluminum ingot.

Ultrasonic cleaning: Pretreated high-purity aluminum ingots are placed in a cleaning agent and treated with ultrasonic waves.

Drying: After ultrasonic cleaning, place the high-purity aluminum ingot in the oven and bake at 60-100℃ for 30-60 minutes.

Melting: Place dried high-purity aluminum in a preheated crucible and melt it by heating at 760-800°C.

Refining treatment: High-purity aluminum is melted and then purified. Specifically: Purification treatment is performed on molten high-purity aluminum using an Ar+graphite automatic degassing stir bar. Argon is injected at 740-760°C for 5-10 minutes to inject the purifier. The amount of purifier injected is 0.1-0.3% of the melt, and this process is maintained for 3-5 minutes. Afterwards, the aluminum melt is left for 10-20 minutes, and a slag remover equivalent to 0.1-0.3% of the melt is added to the aluminum melt and spread evenly to remove surface slag.

Standing: After removing the slag, the aluminum melt is left at 740-760℃ for 8-15 minutes.

b) Melting of rare earth aluminum alloy:

Adjust the temperature of the high-purity aluminum obtained in a) above to 780-820℃, heat to completely melt, and then add rare earth aluminum-lanthanum alloy (purchased from Baotou Rare Earth Research Institute, composition: Al-10La, Fe<0.05) with a set mass ratio. , that is, the lanthanum content of the rare earth aluminum alloy is added according to 0.2±0.02wt%. Heating the rare earth aluminum-lanthanum alloy at 780-820℃ under argon gas atmosphere to completely melt it.

Stirring and warming: Stir the melt for 3-5 minutes to make it uniform, and keep at 760-780°C for 10-20 minutes.

Purification treatment: The entire process is under the protection of argon atmosphere, and purification treatment is carried out after melting the rare earth aluminum-lanthanum alloy. An Ar+graphite automatic degassing stirring rod is introduced to purify the molten rare earth aluminum-lanthanum alloy. The purifier is injected using Ar at 760-780°C for 5-10 minutes, the amount of purifier injected is 0.1-0.3% of the melt, and this process is maintained for 3-5 minutes. During the purification process, there should be no boiling bubbles on the upper surface of the aluminum liquid. Removing slag from the surface of the melt: After 15-20 minutes, add slag remover in an amount equivalent to 0.1-0.3% of the melt and spread evenly to remove slag from the surface.

Standing: After removing the slag, the melt is left at 720-730°C for 10-15 minutes.

3.2) Preparation of composite rare earth alloys

Aluminum melt, rare earth aluminum alloy, aluminum-strontium master alloy and aluminum-titanium-boron master alloy are prepared respectively in the above description, and then mixed and melted to obtain composite rare earth alloy.

In this example, the addition order is that the rare earth aluminum alloy is added to the aluminum melt first, then the aluminum strontium alloy, and finally the aluminum titanium boron alloy. Details are as follows:

Level 1. Material preparation: Weigh high-purity aluminum, aluminum-titanium-boron master alloy, aluminum-strontium master alloy, and rare earth aluminum alloy according to the required mass ratio and preheat.

Based on a total of 100 parts by weight, high purity aluminum: 4.8 parts by weight, aluminum-titanium-boron master alloy: 0.2 parts by weight, aluminum-strontium master alloy: 60 parts by weight, and rare earth aluminum alloy: 35 parts by weight.

Step 2. Rare earth aluminum alloy addition and melting: For the above aluminum melt, the above purified rare earth aluminum alloy is first heated to 780-820℃ to soften it before melting, and then the overall temperature of the aluminum melt is controlled to 760-780℃ and heat preservation. For this purpose, rare earth aluminum alloy is added to the aluminum melt.

The entire process is protected by argon atmosphere and the rare earth aluminum alloy is melted.

Step 3. After the rare earth aluminum alloy is completely melted, adjust the temperature to 750-770℃ and stir for 5-10 minutes.

The entire process is protected by argon atmosphere, and the stirring rod is made of graphite material and preheated to 400-500℃ before stirring.

In other words, after the rare earth aluminum alloy is completely melted, the temperature can be slightly lowered to prevent subsequent grain roughening due to overheating.

Step 4. The molten mass is maintained at 740-760°C, and the holding time is controlled within 5-20 minutes for thermal insulation treatment. At this stage, an alloying reaction occurs.

Step 5. Refining: After completion of heat preservation, purification, degassing and slag removal are carried out. Use argon to blow 0.3 wt% refining agent into the melt, control the ventilation time within 3-8 minutes, then add 0.2 wt% deslagging agent further into the melt, stir for 5 minutes, and leave the melt to dry on the melt surface. Removes slag and impurities. The entire process is protected by an argon atmosphere.

Sampling of the aluminum melt before and during refining is performed and the density of the aluminum melt is determined to estimate the hydrogen content. The measurement method adopts the density method (2.70 g/cm ³ , which is the theoretical value of aluminum), and if the density of the measured sample is close to 2.7 g/cm ³ , it indicates that the internal hydrogen content of aluminum is low. In general, the density of the sample generally cannot reach 2.7 g/cm ³ . The hydrogen content can be estimated if the density of the tested sample is approximately equal to 2.65 g/cm ³ . Vacuum treatment is always performed in the process of estimating the hydrogen content. If the hydrogen content is inadequate, further purification is performed, that is, by repeated addition of refining agent and slag remover.

Step 6. Standing: Rare earth aluminum alloy and purified melt are left standing for 3-5 minutes, the temperature is adjusted to 740-760 ℃.

Step 7. Addition and use of aluminum-strontium master alloy: Add the purified aluminum-strontium master alloy to the melt in step 6 and control the temperature to 780-820 ℃ to completely melt the aluminum-strontium master alloy. The entire process is protected by an argon atmosphere and the aluminum-stenetium master alloy melts.

Step 8. After the aluminum-strontium master alloy is melted, control the temperature to 740-760°C and stir for 3-8 minutes to achieve homogenization. The whole process is protected by argon atmosphere, the stirring rod is made of graphite material, and is preheated to 400-500℃ before stirring.

Step 9. Next, warming is carried out at 725-750 ° C. The warming time is controlled within 15-30 minutes.

Step 10. Purification, degassing and slag removal: After the warming of the melt is completed, argon is introduced, then 0.3 wt% purifier is blown into the aluminum-rare earth composite melt, the ventilation time is controlled to 5-10 minutes, and 0.2 wt% slag remover is added. Add it to the aluminum melt and stir for 5 minutes to remove slag and impurities from the surface of the aluminum-rare earth composite melt. The entire process is protected by an argon atmosphere.

Sampling of the aluminum melt is performed before and during refining to determine the hydrogen content. (Hydrogen content must be more than 2.65 g/cm ³ ;) Vacuum treatment must be performed during the hydrogen measurement process. If the hydrogen content is rejected, further purification is carried out, that is, by repeatedly adding purifier and slag remover.

Step 11. Add aluminum-titanium-boron master alloy: Add the aluminum-titanium-boron master alloy to the melt treated in step 10 above, heat to completely melt, and stir evenly for 3-5 minutes to make the melt homogeneous.

Step 12. Heat preservation: After stirring, keep the melt temperature for 8-12 minutes and adjust the temperature at 715-725℃.

Step 13. Purification, degassing and slag removal: After the warming of the melt is completed, argon is introduced, then 0.3 wt% purifier is blown into the aluminum-rare earth composite melt, the ventilation time is controlled within 5-10 minutes, and 0.2 wt% slag remover is added. Add it to the aluminum melt and stir for 5 minutes to remove slag and impurities from the surface of the aluminum rare earth composite melt. The entire process is protected by an argon atmosphere.

Sampling of the aluminum melt is performed before and during refining to determine the hydrogen content. (Hydrogen content must be more than 2.65 g/cm ³ ;) Vacuum treatment must be performed during the hydrogen measurement process. If the hydrogen content is inadequate, further purification is performed. That is, refiners and slag removers are added repeatedly for further purification until the hydrogen content is acceptable.

Step 14. Casting: Preheat the mold to 300-400℃. Casting is performed after controlling the temperature of the composite rare earth alloy melt obtained in step 13 above to 715-725°C.

Preferably, during casting, oxides on the surface of the aluminum-rare-earth composite melt are filtered through a glass fiber filter, and filtration is performed on the surface of the aluminum-rare-earth composite melt before each casting, followed by casting.

To control cooling of the casting mold, a water cooling method is preferably used to cool the aluminum-rare earth composite melt cast in the mold. During the cooling process, the solidification rate of aluminum melt is controlled to 50-100 ℃/s, and the solidification method is sequential solidification.

The specific amounts of rare earth metals: strontium: titanium or titanium boron in the composite rare earth aluminum alloy are not limited by the above examples. For example, the mass ratio of the total amount of rare earth metals: strontium: titanium or titanium boron may be 1: (0.1-1.2): (0.1-1.2).

4) Preparing modified aluminum alloy blank

Aluminum-silicon-magnesium alloy, composite rare earth aluminum alloy, and aluminum-titanium-boron master alloy have a mass ratio of 99.4:0.4:0.2 for aluminum-silicon-magnesium alloy: composite rare earth aluminum alloy:aluminum-titanium-boron master alloy. It is manufactured.

Melting is then carried out as follows.

Mixing: In the aluminum-silicon-magnesium alloy melt treated in 1) above according to the above ratio, when the temperature is controlled to 740 ± 5 degrees, the composite rare earth aluminum alloy obtained in 3) is first added.

Stirring: Graphite stirrers are used to stir the melt by adding complex rare earth aluminum alloy. During the stirring process, uniform stirring is required and stirring must be continued for 8 minutes;

Keeping warm: After stirring, adjust the temperature to 735℃ for keeping warm, and adjust the keeping time to 20 minutes;

Refining: After warming, add argon, then blow slag remover into the aluminum water, and control the ventilation time to 15 minutes;

Addition of refining agent: Add 0.2% aluminum-titanium-boron master alloy to purified aluminum water, stir when dissolved, and continuously carry out purification;

Warming and standing: After purification, the aluminum water is introduced into the warming pool, the temperature is controlled at 710±3℃, left for 10±2 minutes, and then the slag and impurities on the surface of the aluminum water are removed;

Casting: Preheat the mold at 250-400 ℃, the above temperature is controlled at 700 ± 5 ℃, the refined modified aluminum alloy is cast into the mold, and after cooling, the modified aluminum alloy blank is obtained. The thickness of the modified aluminum alloy blank is 30 mm.

5) Heat treatment

Solution heat treatment: The deformed aluminum alloy blank is placed in a heating furnace and heated to 540°C at a heating rate of 2°C per minute and maintained for 120 minutes.

Water quenching treatment: After the above solution quenching treatment, the modified aluminum alloy blank is placed in a circulating water bath at a temperature of 65°C and water quenched for 3 minutes.

Aging treatment: After water quenching, the modified aluminum alloy blank is kept at 150 ℃ for 120 minutes, then cooled to 110 ℃ at a cooling rate of 2 ℃/min, maintained for 30 minutes, and then naturally cooled to room temperature to produce high-strength composite modified aluminum alloy parts. get

Figure 1 is a photograph of a high-strength composite modified aluminum alloy part, that is, a wheel hub, manufactured in Example 1. FIG. 2 is an image of the metal structure of the rib portion of the wheel hub shown in FIG. 1, where (a) is a low magnification image, (b) is a medium magnification image, and (c) is a high magnification image. From Figure 2, it can be seen that for the metal structure of the aluminum alloy modified and heat treated in this example, the rounder spherical α-Al phase further increases, and the primary α-Al phase and dendrites are basically invisible. That is, the particles are more homogenized and the microstructure is more uniform. Additionally, the spherical α-Al phase is uniformly distributed at the grain boundaries.

Additionally, the mechanical properties of the A356 aluminum alloy (before modification), the blank after modification (modified alloy 1), and the product after heat treatment (Example 1) were evaluated. The evaluation results are shown in Table 1 below.

Table 1 shows the mechanical property evaluation results of the high-strength composite modified aluminum alloy part of Example 1.

mechanical properties Before reformation 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

Table 1 shows that the strength can be greatly improved through the heat treatment of Example 1 even without heat treatment. By combining heat treatment, the yield strength and tensile strength are significantly improved (compared to the undeformed and unheated aluminum alloy ingot, the yield strength and tensile strength are increased by almost 4 times and almost 3 times, respectively) and a high level of elongation (untreated aluminum alloy ingot) (more than a 4-fold increase compared to

Example 2

In this example, compared to Example 1, except that the modifier uses a combination of rare earth aluminum alloy, aluminum-strontium master alloy, and aluminum-titanium or aluminum-titanium-boron master alloy, the remaining contents are as in Example 1. Same as 1.

Below, only other parts related to the processing of deformed aluminum alloy melts are described as follows:

4) Preparing modified aluminum alloy blank

Aluminum-silicon-magnesium alloy, rare earth aluminum alloy, aluminum-strontium alloy and aluminum-titanium-boron master alloy are: Aluminum-silicon-magnesium alloy: Rare earth aluminum alloy (purification treatment of rare earth aluminum alloy is the same as that of Example 1) Aluminum-strontium alloy: It is manufactured according to the mass ratio of aluminum-titanium-boron master alloy of 99.4:0.2:0.2:0.2.

Melting is then carried out as follows.

Mixing: In the aluminum-silicon-magnesium alloy melt after the treatment in 1) above according to the above ratio, the rare earth aluminum alloy is added first when the temperature is controlled at 740±5℃.

Stirring: The graphite stirrer is used to stir the molten melt added with rare earth aluminum alloy, and the stirring process requires uniform stirring and needs to be continuously stirred for 8 minutes;

Keeping warm: After stirring, adjust the temperature to 735℃ for keeping warm, and adjust the keeping time to 20 minutes;

Refining: After warming, add argon, then blow slag remover into the aluminum water, and control the ventilation time to 15 minutes;

Addition of aluminum-strontium master alloy: Add 0.2% aluminum-strontium master alloy to purified aluminum water, stir when dissolved, and continuously carry out purification;

Homogenization: After the aluminum-strontium master alloy is completely melted, adjust the temperature to 740-760℃ and stir for 3-8 minutes to achieve homogenization;

Insulating: Next, the insulating treatment is carried out at 725-750℃, and the insulating time is adjusted to 15-30 minutes;

Addition of refining agent: Add 0.2% aluminum-titanium-boron master alloy to purified aluminum water, stir when dissolved, and continuously carry out purification;

Insulating and standing: After purification, the aluminum water flows into the insulating pool, and the temperature is controlled at 710±3℃, after the aluminum water stands for 10±2 minutes, the slag and impurities on the surface of the aluminum water are removed;

Casting: Preheat the mold at 250-400 ℃, the above temperature is controlled at 700 ± 5 ℃, cast the refined modified aluminum alloy into the mold, and after cooling, obtain the modified aluminum alloy blank.

The metallurgical structure image of the product obtained in this example is similar to the image in Example 1. Details are not described in this specification.

Table 2 shows the mechanical property evaluation results of the high-strength composite modified aluminum alloy part of Example 2.

mechanical properties Before reformation 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

Modified alloy 2 represents the blank after modification without heat treatment.

Table 2 shows that similar results to Example 1 can be obtained even if the heat treatment of Example 2 is used.

At the same time, compared with Example 2, the composite rare earth aluminum alloy was prepared by first melting the rare earth aluminum alloy and the aluminum-strontium master alloy, and the composite modified aluminum alloy portion obtained by modifying the composite rare earth aluminum alloy had higher comprehensive mechanical properties. It can be seen that it has .

Example 3

In this embodiment, compared to Example 1, the rest of the contents are the same except for using ZL111 instead of A356.

For specific preparation, please refer to Example 1. Detailed information is omitted from this specification.

Additionally, the mechanical properties of the ZL111 aluminum alloy (before modification), the blank after modification (Reformed Alloy 3), and the part after heat treatment (Example 3) were evaluated. The evaluation results are shown in Table 3 below.

Table 3 shows the mechanical property evaluation results of the high-strength composite modified aluminum alloy part of Example 3.

mechanical properties Before reformation 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

Table 3 shows that similar results to Examples 1 and 2 can be obtained by using the heat treatment of Examples 1 and 2 and by using the heat treatment of Example 3. That is, the manufacturing process of the present invention is also applicable to eutectic aluminum alloy, and better strength and higher toughness can be obtained. The above description is a preferred embodiment of the present invention. Those skilled in the art should note that various improvements and modifications can be made without departing from the principles disclosed in the present invention, and such improvements and modifications should also be considered within the protection scope of the present invention.

Claims (7)

Step S1, providing an aluminum alloy melt;
Step S2, providing a modifier, the modifier accounts for 0.4-0.6 wt% of the total modified aluminum alloy melt, and the modifier is a composite rare earth aluminum alloy and aluminum-titanium master alloy or a composite rare earth aluminum alloy and aluminum-titanium- It is a combination of a boron master alloy, and the composite rare earth aluminum alloy includes strontium, titanium or titanium boron and a rare earth metal, and the mass ratio of the total amount of rare earth metal:strontium:titanium or titanium boron in the composite rare earth aluminum alloy is 1:(0.1 -1.2):(0.1-1.2),
The rare earth metal of the composite rare earth aluminum alloy is any one or more of lanthanum, cerium, and yttrium;
The step of manufacturing the composite rare earth aluminum alloy is,
Step S211, providing the aluminum melt;
Step S212, providing an aluminum-strontium master alloy, an aluminum-titanium or aluminum-titanium-boron master alloy, and a rare earth aluminum master alloy, and the rare earth metal contained in the rare earth aluminum master alloy is selected from lanthanum, cerium, and yttrium. It is one or more types; and
Step S213, under an inert gas atmosphere, sequentially adding and melting the rare earth aluminum alloy, aluminum-strontium master alloy, aluminum-titanium or aluminum-titanium-boron mother alloy to the aluminum melt to obtain a composite rare earth aluminum alloy; do,
Step S3, adding a modifier to the aluminum alloy melt under an inert gas atmosphere and melting it to obtain a modified aluminum alloy melt;
Step S4, performing casting using the modified aluminum alloy melt to obtain a modified aluminum alloy blank; and
Step S5, heat treatment is performed on the modified aluminum alloy blank, and the heat treatment includes,
solution heat treatment in which the modified aluminum alloy blank is heated to 530-550° C. and held for 100-300 minutes;
Water quenching treatment in which the modified aluminum alloy blank after the solution treatment is placed in a water bath at 60-70°C and quenched with water for 2-4 minutes; and
After the water quenching treatment, the modified aluminum alloy blank is maintained at 150-165 ℃ for 120-280 minutes, then further cooled to 110-130 ℃, maintained for 30-120 minutes, and then naturally cooled to room temperature to produce high-strength composite modified alloy parts. Aging treatment to obtain a method for manufacturing high-strength composite modified aluminum alloy parts, including: The method of claim 1, wherein step S1,
providing an aluminum alloy ingot;
Removing the oxide scale layer on the surface of the aluminum alloy ingot, washing and drying; and
It includes the step of melting the dried aluminum alloy ingot and removing the purification and slag to obtain an aluminum alloy melt,
A method of manufacturing a high-strength composite modified aluminum alloy part, wherein the composition of the aluminum alloy ingot is hypoeutectic aluminum alloy or eutectic aluminum alloy. The method of claim 1, wherein step S3,
Step S310, adding the composite rare earth aluminum alloy to the aluminum alloy melt and melting it to obtain a fourth homogeneous mixed melt; and
Step S320, adding the aluminum-titanium or aluminum-titanium-boron master alloy to the fourth homogeneous mixed melt and continuing to melt to obtain a modified aluminum alloy. A method of producing a high-strength composite modified aluminum alloy part. The method of claim 1, wherein the temperature increase rate of the solution treatment in step S5 is adjusted to 1.5-3 °C/min, and the holding time is adjusted to within 120-180 minutes. The method according to claim 1, wherein the solution treatment, water quenching treatment and aging treatment are continuous treatments,
The water bath is a circulating water bath, and the temperature of the cast aluminum alloy blank is maintained above 55°C after the water quenching treatment and before the aging treatment is performed. The method of claim 1, wherein the aging treatment step cools the temperature from 150-165° C. to 110-130° C. at a cooling rate of 2-5° C./min. A high-strength composite modified aluminum alloy part obtained by the manufacturing method according to any one of claims 1 to 6, and having a tensile strength of 300 MPa or more, a yield strength of 230 MPa or more, and an elongation of 6% or more.