CN115491617B - A kind of Si, Er micro-alloying refines the method for aluminum and aluminum alloy crystal grain - Google Patents

Abstract

The invention discloses a method for microalloying Si and Er to refine aluminum and aluminum alloy grains, belonging to the technical field of aluminum alloy materials. The method adopts Si and Er composite microalloying, by adding an appropriate amount of Si and Er microalloying elements in the alloy preparation process, and through subsequent homogenization-hot rolling-solution treatment, the recrystallized grain boundaries of the alloy are precipitated The grain boundary precipitates rich in Er and Si elements hinder the growth of recrystallized grains, making the grains significantly refined.

Description

A kind of Si, Er microalloying refines the method for aluminum and aluminum alloy crystal grain

technical field

The invention relates to a method for refining aluminum alloy crystal grains, mainly relates to the effect of Si and Er microalloying elements on aluminum and aluminum alloy grain refining, and belongs to the technical field of alloy materials.

technical background

Aluminum alloys are widely used in aerospace, automobile manufacturing and other fields due to their excellent properties such as high strength and corrosion resistance. With the continuous development of aluminum alloys and their increasing applications in high-tech fields, higher requirements are placed on the structure and properties of aluminum alloys.

The recrystallization grain size can significantly affect the properties of the alloy. Some scholars have found that inhibiting the recrystallization of the alloy and promoting the dynamic recrystallization of the alloy during thermal processing can make the alloy produce extremely fine grains, improve the performance of the material, and the alloy also has The possibility of superplasticity.

At present, in the research of recrystallization grain refinement, the improvement of the heat treatment process is mainly used to further inhibit the recrystallization of the alloy and play the role of refining the recrystallization grains. The specific processes include solution quenching-overaging-intermediate deformation heat treatment (ITMT) process of solution quenching-overaging-medium temperature deformation-solution recrystallization treatment, recrystallization annealing-predeformation-low temperature annealing-rolling-recrystallization annealing process, and only applicable Solution treatment-rolling deformation-continuous rolling deformation-recrystallization treatment of seven-series alloys. Although the above-mentioned processes can refine the recrystallized grains of the alloy, they have the disadvantages of high energy consumption, difficult operation, complex process, and small application range of the process.

In view of the complexity and limitations of the above heat treatment process, it is particularly important to design a recrystallization grain refinement method that is not limited by the heat treatment process. Many studies have shown that microalloying can have a beneficial effect on the grain structure and mechanical properties of aluminum alloys. Adding trace Si elements to Al-Cu-Mg can inhibit the growth of precipitates in the alloy, making the precipitates in the matrix finer and more stable. The uniform distribution accelerates the aging strengthening of the alloy and improves the mechanical properties of the alloy. At the same time, some studies have shown that adding a small amount of Er to the Al-Mg alloy can effectively refine the as-cast grains of the alloy, increase the thermal stability of the alloy, and increase the recrystallization temperature by about 50 °C. Therefore, it is possible to carry out microalloying by co-addition of Si and Er elements, and explore its influence on the recrystallization grain size of the alloy, thereby improving the overall performance of the alloy.

Based on the above technical background, the present invention adopts the homogenization-rolling heat treatment process through Si and Er microalloying, so that the grain boundary precipitation phase rich in Er and Si elements is precipitated at the recrystallization grain boundary of the final alloy, so that the aluminum alloy The recrystallized structure has been refined, so that the aluminum alloy with better mechanical properties can be obtained, which meets the higher requirements for the structure and performance of the aluminum alloy in the industrial field.

Contents of the invention

The object of the present invention is to invent a method for refining aluminum alloy crystal grains, through the currently widely used microalloying method, adding or compounding Si and Er microalloying elements to aluminum and aluminum alloys, through homogenization -The post-rolling heat treatment process makes the grain boundary precipitation phase rich in Er and Si elements precipitate out at the recrystallization grain boundary of the alloy after rolling, which plays a role in refining the recrystallization grains of the aluminum alloy and at the same time improves the final aluminum alloy. The mechanical properties of the alloy can be improved to prepare an aluminum alloy with excellent comprehensive properties.

A method for refining aluminum and aluminum alloy grains by Si and Er microalloying, characterized in that an appropriate amount of Si and Er microalloying elements are compounded into the pure aluminum or aluminum alloy matrix, and the alloy ingot is homogenized Heat treatment and rolling are carried out, and then heat treatment is carried out, and the grain growth is hindered by the precipitation of Si and Er at the recrystallization grain boundary.

The aluminum alloy grain refinement method provided by the present invention is characterized in that Si and Er microalloying elements are added, the weight percentage of Si element in the final alloy is 0.15% to 0.3%, and the weight percentage of Er element in the final alloy is The percentage is 0.1% to 0.25%.

Appropriate Si and Er microalloying elements are compounded into pure aluminum, so that the weight percentage of Si element in the final alloy is 0.15%-0.3%, and the weight percentage of Er element in the final alloy is 0.1%-0.25%.

An appropriate amount of Si and Er microalloying elements are compounded into the aluminum alloy matrix, wherein the aluminum alloy matrix is preferably Al-Cu-Mg, Al-Zn-Mg-Cu alloy and the like.

The method for refining grains of aluminum alloy provided by the present invention is characterized in that the aluminum alloy obtained by casting is homogenized at 440° C. to 460° C./6h.

The aluminum alloy grain refinement method provided by the present invention is characterized in that heat treatment and rolling after homogenization treatment: heat treatment at 430°C-460°C for 1-2 hours, and rolling at the heat treatment temperature, the deformation amount is 65 % to 80%, preferably rolling in one pass.

The method for refining aluminum alloy grains provided by the present invention is characterized in that the temperature of the heat treatment after the rolling is 530°C-550°C.

The present invention is realized through the following technical solutions: a method for refining aluminum alloy crystal grains includes (1) designing the composition of the alloy; (2) preparing an ingot alloy by melting in a graphite crucible and casting an iron mold; Carry out homogenization treatment; (4) carry out hot rolling to alloy; (5) carry out heat treatment to alloy again.

Step (1) Design the composition of the prepared aluminum alloy, and select appropriate amount of microalloying elements, namely Si and Er, in order to obtain an aluminum alloy with fine grains and excellent properties.

Step (2) The specific process of preparing the ingot alloy by using graphite crucible melting and iron mold casting is as follows: first put the raw material into the graphite crucible, heat and melt it in a high-temperature melting furnace at 800±5°C, and keep it standing after reaching the temperature, such as When pure Mg needs to be added, it needs to be wrapped with aluminum foil to reduce the burning loss of Mg, and then fully stirred. After it is fully melted, C ₂ Cl ₆ is degassed, stirred, kept warm, and then cast in an iron mold to obtain the aluminum alloy casting ingot.

Step (3) On the basis of step (2), the ingot obtained by casting is placed in a heat treatment furnace, and a homogenization treatment is carried out at a temperature of 440° C. to 460° C. for 6 hours.

Step (4) On the basis of step (3), heat-treat the homogenized sample at 430°C-460°C for 1-2h, and roll the sample at the heat-treatment temperature until the deformation is 65%. ~80%.

Step (5) On the basis of step (4), conduct heat treatment at 530-550° C., raise the temperature from room temperature to 530-550° C., keep it warm for 1 hour, and then water quench to room temperature within 10 seconds.

In the present invention, after adding Er and Si to the aluminum alloy together, through the subsequent homogenization-hot rolling and heat treatment process, the grain boundary precipitation phase rich in Er and Si elements is precipitated at the recrystallization grain boundary of the alloy, and the recrystallization is hindered The grain grows, so that the recrystallization structure of the aluminum alloy is refined, and the aluminum alloy with excellent performance is obtained.

Description of drawings:

Figure 1(a): Metallographic picture of the Al-0.25Er alloy in Example 1 after solution treatment.

Figure 1(b): Metallographic picture of the Al-0.25Er-0.3Si alloy in Example 1 after solution treatment.

Fig. 2(a): metallographic picture of the Al-4Cu-0.5Mg alloy in Example 2 after solution treatment.

Figure 2(b): Metallographic picture of the Al-4Cu-0.5Mg-0.15Si alloy in Example 2 after solution treatment.

Fig. 2(c): metallographic picture of the Al-4Cu-0.5Mg-0.15Si-0.1Er alloy in Example 2 after solution treatment.

Figure 3(a): Metallographic picture of the Al-4.5Zn-1.5Mg-1.0Cu alloy in Example 3 after solution treatment.

Figure 3(b): Metallographic picture of the Al-4.5Zn-1.5Mg-1.0Cu-0.35Si alloy in Example 3 after solution treatment.

Figure 3(c): Metallographic picture of the Al-4.5Zn-1.5Mg-1.0Cu-0.35Si-0.1Er alloy in Example 3 after solution treatment.

Figure 4: TEM image of the alloy after the co-addition of Er and Si elements

Detailed ways:

The present invention will be further described below in conjunction with the examples, but the present invention is not limited to the following examples.

Example 1: Two aluminum alloy ingots with different compositions were prepared by graphite crucible smelting and iron mold casting, and the raw materials used were high-purity aluminum, Al-24%Si, and Al-6%Er intermediate alloys. First, calculate the quality of the required experimental raw materials according to the designed alloy composition, put high-purity aluminum into a graphite crucible, heat and melt it in a high-temperature melting furnace at 800±5°C, and then add Al-24 after the pure aluminum is completely melted %Si, Al-6% Er intermediate alloy, fully stirred, after it is fully melted, C ₂ Cl ₆ degassed, stirred, kept warm, and then cast in an iron mold, and the alloy was air-cooled to obtain an ingot. Two alloy materials, Al-0.25Er and Al-0.25Er-0.3Si, were prepared. The two as-cast alloys were homogenized at 450°C for 6 hours, and hot rolled at 450°C with a deformation of 80%. After heat preservation at 540°C for 1h, water cooling was carried out for solid solution treatment. The final treated sample was polished with sandpaper, and then the surface of the sample sample was polished with polishing paste, and then Keller reagent (95% H ₂ O + 2.5% HNO ₃ +1.5 %HCl+1.0%HF) to corrode the sample, and finally in a dry environment, use a metallographic microscope to observe the grain size of the sample after the solution treatment process. As shown in Figure 1(a), it is the metallographic picture of Al-0.25Er after solid solution treatment, compared with the metallographic picture of Al-0.25Er-0.3Si alloy shown in Figure 1(b), and the average Particle size, table 1 is obtained:

Table 1: Average grain size of the alloy

It is obvious that the compound addition of Si and Er reduces the average grain size of the alloy, and the effect of recrystallization grain refinement is obvious, indicating that the microalloying effect of Si and Er has a significant effect on grain refinement of aluminum alloy. As shown in Figure 4, it is a TEM image of the grain boundary of Al-0.25Er-0.3Si alloy. It can be clearly observed in the figure that there are black precipitates containing Si and Er elements in the grain boundary. The existence of these precipitates hinders The growth of the recrystallized grains is prevented, and the recrystallized grains of the alloy are refined.

Example 2: Two aluminum alloy ingots with different components were prepared by graphite crucible smelting and iron mold casting. The raw materials used were high-purity aluminum, pure magnesium, Al-50% Cu, Al-24% Si, Al-6% Er master alloy. First, calculate the quality of the required experimental raw materials according to the designed alloy composition, first put high-purity aluminum into a graphite crucible, heat and melt it in a high-temperature melting furnace at 800±5°C, and then add Al- 50%Cu, Al-24%Si, Al-6%Er intermediate alloys, after all the furnace materials are melted, add Mg wrapped in aluminum foil, keep warm for about 10min, then fully stir, after it is fully melted, C ₂ Cl ₆ Degassing, stirring, heat preservation and standing, then iron mold casting, and the alloy is air-cooled to obtain an ingot. Al-4Cu-0.5Mg, Al-4Cu-0.5Mg-0.15Si, Al-4Cu-0.5Mg-0.15Si-0.1Er three alloy materials were prepared, and the three as-cast alloys were homogenized at 450°C for 6 hours and then heated Rolling, the deformation amount is 80%, and then the alloy is kept at 540 ° C for 12 hours and then water-cooled for solution treatment. The experimental sample is cut into a small sample of 10 mm × 10 mm × 5 mm, and after grinding with sandpaper, the polished sample is then treated with polishing paste. The surface of the sample was polished, then corroded with Keller reagent (95% H ₂ O + 2.5% HNO ₃ + 1.5% HCl + 1.0% HF), and finally in a dry environment, use a metallographic microscope to analyze the solid solution treatment process The grain size of the samples was then observed. As shown in Figure 2(a), 2(b) and 2(c), Al-4Cu-0.5Mg, Al-4Cu-0.5Mg-0.15Si, Al-4Cu-0.5Mg-0.15Si-0.1Er The metallographic pictures of the alloys after solid solution treatment, and the average grain size of the three alloys are counted, and Table 2 is obtained:

Table 2: Alloy average grain size

By comparing the average grain size of the three alloys, the addition of Si alone reduced the recrystallization grain size of the alloy, while the compound addition of Si and Er made the recrystallization grain size of the alloy significantly refined, indicating that Si, Er The effect of compound addition of Er on the recrystallization grain refinement of the alloy is remarkable.

Example 3: Two kinds of aluminum alloy ingots with different components were prepared by graphite crucible smelting and iron mold casting. The raw materials used were high-purity aluminum, pure magnesium, pure zinc, Al-50% Cu, Al-24% Si, Al- 6% Er master alloy. First, calculate the quality of the required experimental raw materials according to the designed alloy composition, first put high-purity aluminum into a graphite crucible, heat and melt it in a high-temperature melting furnace at 800±5°C, and then add Al- 50%Cu, Al-24%Si, Al-6%Er intermediate alloys, after all the furnace materials are melted, add pure magnesium and pure zinc wrapped in aluminum foil, keep warm for about 10min, and then fully stir until they are fully melted , C ₂ Cl ₆ degassing, stirring, heat preservation and standing, then iron mold casting, and the alloy is air-cooled to obtain an ingot. Al-4.5Zn-1.5Mg-1.0Cu, Al-4.5Zn-1.5Mg-1.0Cu-0.35Si, Al-4.5Zn-1.5Mg-1.0Cu-0.35Si-0.1Er three alloy materials were prepared. After the as-cast alloy was homogenized at 450°C for 15 hours, it was hot-rolled at 450°C with a deformation of 80%. The alloy was kept at 540°C for 1 hour and then water-cooled for solid solution treatment. The treated alloy was polished with sandpaper. A good sample is then polished with polishing paste, then corroded with Keller reagent (95% H ₂ O + 2.5% HNO ₃ + 1.5% HCl + 1.0% HF), and finally in a dry environment, use A metallographic microscope was used to observe the grain size of the sample after the solid solution treatment process. As shown in Figure 3(a), 3(b) and 3(c), Al-4.5Zn-1.5Mg-1.0Cu, Al-4.5Zn-1.5Mg-1.0Cu-0.35Si, Al-4.5Zn- The metallographic pictures of the three alloys of 1.5Mg-1.0Cu-0.35Si-0.1Er after solid solution treatment, by comparing the metallographic pictures, it can be clearly observed that the addition of Si and Er elements reduces the recrystallization grain size of the alloy, And similar to the results of Example 2, the addition of a small amount of Si makes the recrystallized grains of the alloy finer, and the grain refinement effect is more significant after the compound addition of Si and Er.

Claims (2)

1. A method for refining aluminum and aluminum alloy grains by micro-alloying Si and Er is characterized in that a proper amount of micro-alloying elements Si and Er are added into a pure aluminum or aluminum alloy matrix in a compounding way, an alloy ingot is subjected to heat treatment and rolling after homogenization, and then heat treatment is performed, and the grains are prevented from growing by precipitation of Si and Er at a recrystallization grain boundary;

adding Si and Er microalloying elements, wherein the weight percentage of the Si element in the final alloy is 0.15-0.3%, and the weight percentage of the Er element in the final alloy is 0.1-0.25%;

carrying out homogenization treatment at 440-460 ℃/6h on the aluminum alloy obtained by casting;

heat treatment and rolling after homogenization treatment: heat treatment is carried out for 1-2 h at 430-460 ℃, rolling is carried out at the heat treatment temperature, the deformation is 65-80%, and 1-pass rolling is carried out;

the temperature of the heat treatment after rolling is 530-550 ℃;

the aluminum alloy matrix is Al-Cu-Mg or Al-Zn-Mg-Cu alloy.

2. The method for refining aluminum and aluminum alloy grains by micro-alloying of Si and Er according to claim 1, wherein the heat treatment is carried out at 530-550 ℃, the temperature is raised from room temperature to 530-550 ℃, the heat is preserved for 1h, and then the water quenching is carried out for 10s to room temperature.

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