CN103789583B - Quick aging response type Al-Mg-Si-Cu-Zn system Alloy And Preparation Method - Google Patents

Abstract

The present invention proposes a novel Al-Mg-Si-Cu-Zn series alloy with fast aging response and a preparation method thereof, which fully utilizes the main strengthening phases of Al-Mg-Si and Al-Zn-Mg-Cu series alloys The synergistic precipitation and synergistic strengthening of Mg ₂ Si, MgZn ₂ and their transition phases make the new Al-Mg-Si-Cu-Zn alloy exhibit excellent rapid aging response characteristics during the aging process. Due to the simultaneous addition of Mg, Si, Cu and Zn elements, especially the addition of element Zn, the natural aging deterioration effect of conventional Al-Mg-Si-Cu alloys is suppressed to a certain extent, and the strength of the alloy is found to be higher after pre-aging treatment at a certain temperature. low temperature and good stability at room temperature, which is beneficial to the subsequent stamping and forming of alloy sheets; the strength of pre-aged alloys can be greatly improved after high-temperature aging treatment, and the maximum strength increment after short-term artificial aging at 185°C for 20 minutes is nearly 150MPa, far Higher than traditional AA6016 and AA6111 alloys. This fast aging response characteristic is not only suitable for the preparation of automobile outer panels, but also suitable for related fields that have specific requirements for the aging precipitation speed of alloy plates.

Description

Rapid aging response type Al-Mg-Si-Cu-Zn alloy and its preparation method

technical field

The invention belongs to the technical field of aluminum alloys, and relates to a novel Al-Mg-Si-Cu-Zn alloy that can be applied industrially and a preparation method thereof, especially developed for the aluminum alloy with fast aging response characteristics urgently needed in the automotive field, and can be used Guarantee the dual requirements of high formability and high paint hardening performance for aluminum alloys for lightweight automotive body panels.

Background technique

In recent years, with the continuous acceleration of the lightweight process of automobiles, the development and related research of aluminum alloy sheets for automobiles have also made great progress, especially because aluminum alloys have the advantages of low density, high strength, corrosion resistance and high formability. , and its application in the lightweight process of automobiles has also increased rapidly. Typical aluminum alloys for automobile body panels include 2xxx, 5xxx and 6xxx alloys, among which the common 6xxx alloys are AA6009, AA6010, AA6016, AA6111 and AA6022.

Although heat-treatable Al-Mg-Si alloys have better comprehensive properties, it has been found in the research and application process that if the alloys are directly subjected to solution quenching at 500-570°C and then stamped, their formability is better. However, in the actual production process, most of the plates need to be transported to the automobile manufacturer for subsequent stamping and forming. During this period, the strength of the alloy plate will increase to a certain extent during the natural placement process, which will reduce the formability of the alloy plate and the subsequent Baking paint hardening performance, this phenomenon is the so-called natural aging deterioration effect. Therefore, the preparation process commonly used in the preparation process of 6xxx series aluminum alloys for automobiles is as follows: alloy smelting and casting → homogenization → hot rolling → cold rolling → solid solution → pre-aging (T4P treatment) → stamping → painting → 170- 185°C baking paint treatment and other processes. Due to the particularity of the preparation of automobile sheets, it is inevitable that the T4P state of the alloy before forming has a lower strength, and the strength of the alloy can be greatly improved during the baking process (that is, the T8X state), which can ensure that the alloy sheet has a higher strength. Good anti-sinking ability, etc., so alloy composition design and heat treatment process development are the key ways to solve this problem.

In the past few years, a lot of research has been done on how to improve the hardening performance of alloy baking paint, no matter from the design of new alloys, such as optimizing the content of Mg/Si and Cu, or optimizing the pre-aging process, such as patents US6267922B1, US6117252, EP1967599A1 and CN818123A. , but the hardening increment of the alloy baking paint is still not ideal, even the baking paint hardening increment of the commercial AA6016 and AA6111 alloys is only about 80MPa. Therefore, greatly improving the aging response speed of alloys is not only of great significance for the further improvement of the hardening performance of aluminum alloy paint for automobiles and the acceleration of the lightweight process of automobiles, but also has important guiding significance for the development of new aluminum alloys.

Considering that reducing the content of solute elements Mg, Si, Cu and Fe can reduce the strength of the T4 state alloy and improve the formability of the alloy, but the reduction of Mg, Si and Cu elements will also reduce the paint hardening ability of the alloy. In addition, considering that the MgZn ₂ strengthening phase can greatly increase the strength of Al-Zn-Mg-Cu alloys, if the two main strengthening phases of Al-Mg-Si and Al-Zn-Mg-Cu alloys can be used simultaneously Mg ₂ Si and MgZn ₂ or their transition phases are used as the strengthening phase of the new Al-Mg-Si alloy to achieve the purpose of multi-phase synergistic precipitation and multi-phase synergistic strengthening. The developed alloy will definitely show excellent rapid aging Responsiveness. The present invention carries out new alloy composition design and process development according to this design idea.

Contents of the invention

In order to overcome the deficiencies of the prior art, the present invention aims at the unsatisfactory characteristics of conventional Al-Mg-Si alloy aging response speed and age hardening performance, and develops a new type of Al-Mg-Si-Cu-Zn with fast aging response characteristics. System alloy, make full use of Mg ₂ Si and MgZn ₂ multi-phase synergistic precipitation and synergistic strengthening so that the overall performance of the alloy is greatly improved. The alloy of the invention is particularly suitable for the manufacture of aluminum alloys for the outer panels of automobile bodies, so that the outer panels of the automobile bodies have excellent baking paint hardening performance after being stamped and formed.

The present invention first selects the composition range of the Al-Mg-Si-Cu-Zn alloy with a multi-phase structure through composition design and optimization, and then prepares the designed alloy through processes such as smelting and casting and studies its aging precipitation behavior. The composition of the new Al-Mg-Si-Cu-Zn alloy with fast aging response was finally determined. The specific preparation process is as follows: FactSage phase diagram calculation→Al-Mg-Si alloy composition selection→alloy preparation and melting and casting→ingot homogenization→hot rolling deformation→intermediate annealing→cold rolling deformation→solution quenching→multi-stage aging deal with.

The first object of the present invention is to propose a novel Al-Mg-Si-Cu-Zn series aluminum alloy with fast aging response characteristics, which is characterized in that the chemical composition and mass percentage content of the alloy are: Zn: 0.10 ～3.7wt%, Mg0.3～1.2wt%, Si0.3～1.2wt%, Cu0.05～0.7wt%, Fe≤0.3wt%, Mn≤0.3wt%, Cr≤0.2wt%, Ti≤0.2 wt%, the balance is Al.

Preferably, the Zn, Si and Cu content ranges of its chemical composition are: Zn0.4-3.5wt%, Si0.8-1.1wt%, Cu0.15-0.35wt%.

Preferably, the Mg/Si mass ratio of the chemical components Mg and Si ranges from 0.5 to 1.

The second object of the present invention is to propose a method for preparing the above-mentioned novel Al-Mg-Si-Cu-Zn series aluminum alloy with fast aging response characteristics, the preparation method comprising the following steps:

Step 1, melting and casting;

Step two, two-stage homogenization;

Step 3, hot rolling deformation;

Step 4, intermediate annealing;

Step five, cold rolling deformation;

Step 6, solution treatment above 540°C;

Step 7, water quenching treatment;

Step eight, multi-stage aging treatment.

Preferably, the two-stage homogenization in the second step is as follows: the alloy sample after smelting and casting is heated from room temperature to 470-485°C at a heating rate of 20-40°C/h for 2-5h, and then heated at a temperature of 20-40°C/h. ~40°C/h continue to heat up to 545~555°C for 14~20h, and finally take it out when the temperature is lowered to 100°C with the furnace at a cooling rate of 20~40°C/h.

Preferably, the hot-rolling deformation in step three is specifically: the starting rolling temperature is 545-555°C, the total hot-rolling deformation is >90%, and the finishing rolling temperature is ≥300°C;

Preferably, the intermediate annealing in step 4 specifically includes placing the hot-rolled and deformed alloy sample directly into a heat treatment furnace at 350-450° C. for intermediate annealing for 1-3 hours, and then cooling in air.

Preferably, the cold rolling deformation in the fifth step has a total cold rolling deformation between 50% and 75%, and a pass reduction between 15% and 25%.

Preferably, the solution treatment above 540°C in the step six is specifically: performing solution treatment at 545-555°C/1-6min in a salt bath furnace; the water quenching treatment in the step seven is to dissolve The final alloy samples were directly quenched in water.

Preferably, the multi-stage aging treatment in step 8 is to transfer the alloy sample after water quenching treatment to a pre-aging furnace within 2 to 5 minutes for pre-aging treatment at 70-140°C/9-15h, and then in Place it at room temperature for 14 days, and finally carry out artificial aging at 185°C; or transfer the alloy sample after water quenching to a pre-aging furnace at 70-140°C within 2 to 5 minutes and cool it down at a cooling rate of 1-15°C/h to Take it out at 20-40°C, then place it at room temperature for 14 days, and finally carry out artificial aging at 185°C.

By adopting the above-mentioned technical scheme, the present invention has the following advantages: the novel Al-Mg-Si-Cu-Zn alloy of the present invention can make full use of the interaction between the main alloy elements Mg, Si, Cu and Zn elements in the matrix. Through the appropriate heat treatment regulation, a variety of strengthening phases are precipitated synergistically, and finally a large number of different types of strengthening phases are uniformly dispersed in the alloy matrix, so that the alloy can obtain a relatively large increase in strength within a short aging time, that is, To achieve the so-called fast time response characteristics. The alloy of the present invention is very suitable for the further development and production of aluminum alloy outer plate materials for automobiles, which are more researched at present.

Description of drawings

Fig. 1 The change law of hardness of several new aluminum alloys directly subjected to artificial aging after solution quenching.

Fig. 2 Changes in hardness of several new aluminum alloys after solution quenching and natural aging.

Figure 3 DSC analysis results of several new aluminum alloys after solution quenching and natural aging for 14 days.

Fig. 4 Changes in hardness of several new aluminum alloys after solution quenching, natural aging for 14 days, and then artificial aging at 185°C.

Fig. 5 Changes in hardness of several new aluminum alloys after pre-aging treatment in the natural aging process.

Figure 6 DSC analysis results of several new aluminum alloys after pre-aging + natural aging for 14 days.

Fig. 7 Changes in hardness of several new aluminum alloys after pre-aging + natural aging for 14 days and then aging at 185°C.

Fig. 8 TEM microstructure of 5# alloy in T4P state when the temperature is raised to 250°C at 10°C/min.

detailed description

The present invention will be further supplemented and described below in conjunction with specific embodiments.

The raw materials are 99.9wt% high-purity aluminum, industrial pure Mg, industrial pure Zn, master alloys Al-20wt%Si, Al-50wt%Cu, Al-20wt%Fe, Al-10wt%Mn, etc. The specific smelting process in the resistance furnace is as follows: first add all the pure aluminum to the crucible, set the furnace temperature at 850°C, and add Al-20wt%Si, Al-50wt%Cu, Al-20wt%Fe after the pure aluminum is melted , Al-10wt%Mn master alloy, and add a covering agent (50wt%NaCl+50wt%KCl); continue to heat the melt until the master alloy melts, and stir it after the melt temperature reaches 750°C to mix the solute elements evenly, Then keep the temperature at 750°C for 30 minutes and set the furnace temperature to cool the melt down to 710°C, then add pure Zn and pure Mg into the melt, and stir thoroughly to dissolve them; when the melt temperature reaches 730°C again, take samples for analysis Composition, if the measured value of the composition is lower than the design value, add a certain amount of master alloy appropriately according to the burning loss situation, if the measured value of the composition is higher than the design value, add a certain amount of pure metal aluminum for dilution according to the excess value; continue to wait for the melt After rising to 740°C, remove slag, add refining agent for degassing and refining; then add Al-5wt%Ti-1wt%B grain refiner when the melt temperature is lowered to about 720°C and carry out proper stirring, and finally here After the temperature was kept for 10 minutes, the melt was cast into a steel mold surrounded by water cooling. The specific chemical composition of implementing the invention alloy is shown in Table 1.

Table 1 The chemical composition of the invention alloy (mass percentage, wt%)

Mg Si Cu Fe mn Zn Cr Ti Al 1# 0.6 0.9 0.2 0.1 0.07 0 ≤0.2wt% ≤0.01wt% margin 2# 0.6 0.9 / 0.1 0.07 3.0 ≤0.2wt% ≤0.01wt% Margin 3 --> 3# 0.6 0.9 0.2 0.1 0.07 0.5 ≤0.2wt% ≤0.01wt% margin 4# 0.6 0.9 0.2 0.1 0.07 1.5 ≤0.2wt% ≤0.01wt% margin 5# 0.6 0.9 0.2 0.1 0.07 3.0 ≤0.2wt% ≤0.01wt% margin

Invented alloy ingots are homogenized in a circulating air furnace. The treatment process is: put the alloy ingots into the circulating air furnace, turn on the power, start heating at a heating rate of 20-70°C/h, and wait until the temperature reaches 460-490 ℃ for 1~7h, then continue to heat up at 20~70℃/h to 540~560℃ for 10~25h, and then take out the sample when cooling down to 100℃ with the furnace at a cooling rate of 20~70℃/h; Then the ingot is subjected to hot-rolled deformation→intermediate annealing→cold-rolled deformation. In order to better optimize the composition, some samples are directly taken from the homogenized state, and some are taken from the cold-rolled state, and then the cut block samples are put into Solid solution treatment for 1-10min in a salt bath furnace at 540-560°C, followed by water quenching. Finally, single-stage or multi-stage aging treatment is performed on the quenched sample, and DSC analysis, microhardness and tensile properties are measured to analyze the changes of alloy precipitation behavior and rapid aging response. The specific implementation is as follows:

Example 1

After the invention alloys 1#, 2# and 5# are smelted and cast, they are subjected to homogenization treatment. The treatment process is: start to heat up at a heating rate of 20-40°C/h, and keep warm for 2~ 5h, then continue to heat up at 20-40°C/h to 545-555°C for 14-20h, and then take out the sample when cooling down to 100°C with the furnace at a cooling rate of 20-40°C/h. Then directly cut the sample from the homogenized bulk material and place it in a salt bath furnace for 545-555°C/1-6min solid solution treatment (i.e., carry out 1-6min in a salt bath furnace at 545-555°C solution treatment) and water quenching treatment, and then directly placed in an aging furnace at 185°C for artificial aging for different times, and the aging precipitation behavior of various alloys was compared (see Figure 1 for details).

Example 2

After the invention alloys 1#, 2#, 3#, 4# and 5# are smelted and cast, they are homogenized. The treatment process is: start to heat up at a heating rate of 20-40°C/h, and wait until the temperature reaches 470 Insulate at ~485°C for 2~5h, then continue to heat up at 20~40°C/h to 545~555°C for 14~20h, and then take out the sample when cooling down to 100°C with the furnace at a cooling rate of 20~40°C/h . Then cut the sample directly from the homogenized bulk material and place it in a salt bath furnace for 545～555℃/1-6min solid solution and water quenching treatment, and then directly perform natural aging at room temperature to measure the alloy The change law of hardness with natural aging time (see Figure 2 for details). In addition, DSC analysis was carried out on the 14-day natural aging sample. The specific implementation plan is: cut out a disc with a diameter of 3mm×1mm and a mass of about 15mg, and use a differential scanning calorimeter Q2000 (DSC) for differential thermal analysis. High-purity Al was used as a standard sample and heated from 20°C to 400°C at a heating rate of 10°C/min. Based on this, the difference in aging precipitation behavior of alloys with different compositions can be further grasped (see Figure 3 for details).

Example 3

After the invention alloys 1#, 2#, 3#, 4# and 5# are smelted and cast, they are homogenized. The treatment process is: start to heat up at a heating rate of 20-40°C/h, and wait until the temperature reaches 470 Insulate at ~485°C for 2-5 hours, then continue to heat up at 20-40°C/h to 545-555°C and hold for 14-20 hours, and then take out the sample at a cooling rate of 20-40°C/h to 100°C with the furnace . Then directly cut the sample from the homogenized block material and place it in a salt bath furnace for 545～555℃/1-6min solid solution and water quenching treatment, and then carry out natural aging for 14 days at room temperature (T4 state), and finally the natural aging state samples were subjected to artificial aging treatment at 185°C for different times, and the change law of hardness of the alloy was measured (see Figure 4 for details).

Example 4

After the invention alloys 1#, 2#, 3#, 4# and 5# are smelted and cast, they are homogenized. The treatment process is: start to heat up at a heating rate of 20-40°C/h, and wait until the temperature reaches 470 Insulate at ~485°C for 2~5h, then continue to heat up at 20~40°C/h to 545~555°C for 14~20h, and then take out the sample when cooling down to 100°C with the furnace at a cooling rate of 20~40°C/h . Then cut the sample directly from the homogenized bulk material and place it in a salt bath furnace for solid solution and water quenching treatment at 545-555°C/1-6min, and then ensure that it is transferred to the pre-aging furnace within 2-5min Pre-aging treatment at 70-140°C/9-15h was carried out in the middle, and finally the pre-aged sample was subjected to natural aging at room temperature, and the change law of alloy hardness with natural aging time was measured (as shown in Figure 5). In addition, in order to compare the differences in the precipitation behavior of alloys with different components, corresponding DSC analysis was also carried out. The specific implementation plan is: cut out a disc with a diameter of 3mm×1mm and a mass of about 15mg, and use a differential scanning calorimeter Q2000 (DSC ) for differential thermal analysis, using high-purity Al as a standard sample, heating from 20°C to 400°C at a heating rate of 10°C/min. The corresponding DSC curve is shown in Fig. 6.

Example 5

After the invention alloys 1#, 2#, 3#, 4# and 5# are smelted and cast, they are homogenized. The treatment process is: start to heat up at a heating rate of 20-40°C/h, and wait until the temperature reaches 470 Insulate at ~485°C for 2-5 hours, then continue to heat up at 20-40°C/h to 545-555°C and hold for 14-20 hours, and then take out the sample at a cooling rate of 20-40°C/h to 100°C with the furnace . Then directly cut the sample from the homogenized bulk material and place it in a salt bath furnace for solid solution and water quenching treatment at 545-555°C/1-6min, and then ensure that it is transferred to the pre-aging furnace within 2-5min Pre-aging treatment at 70-140℃/9-15h in the middle, and place the pre-aging sample at room temperature for 14 days to stabilize the performance of the alloy (that is, the T4P(1) state), and finally treat the T4P(1) state sample Artificial aging treatment at 185°C for different times, and the change law of hardness of the alloy was measured (see Figure 7 for details).

Example 6

After the invention alloys 1#, 2#, 3#, 4# and 5# are smelted and cast, they are homogenized. The treatment process is: start to heat up at a heating rate of 20-40°C/h, and wait until the temperature reaches 470 Insulate at ~485°C for 2~5h, then continue to heat up at 20~40°C/h to 545~555°C for 14~20h, and then take out the sample when cooling down to 100°C with the furnace at a cooling rate of 20~40°C/h . Then directly cut the sample from the homogenized bulk material and place it in a salt bath furnace for solid solution and water quenching treatment at 545~555°C/1-6min, and then ensure that it is transferred to 70-140°C within 2~5min. ℃ in the pre-aging furnace at a cooling rate of 1-15°C/h to 20-40°C and take it out, and place the pre-aging sample at room temperature for 14 days to stabilize the alloy performance (that is, the T4P(2) state), and finally The T4P(2) state sample was subjected to artificial aging treatment at 185°C/20min, and the hardness increment of the alloy was measured (see Table 2 for details).

Example 7

After the alloys 1# and 5# of the invention are smelted and cast, they are homogenized. The treatment process is: start to heat up at a heating rate of 20-40°C/h, wait for the temperature to reach 470-485°C for 2-5 hours, and then Continue to heat up at 20-40°C/h to 545-555°C for 14-20h, and then take out the sample when the temperature is lowered to 100°C with the furnace at a rate of 20-40°C/h. After homogenization, the ingot is cut and milled, reheated to 545-555°C for hot rolling, the total deformation of hot rolling is >90%, the final rolling temperature is ≥300°C, and the final hot rolling thickness is 4.0mm; The finished sheet is annealed at 350-450°C/1-3h, and then cold-rolled to a thickness of 1mm, the pass reduction is 15-25%, and the total deformation is 75%; the cold-rolled sheet is 545～555℃/1-6min solid solution and water quenching treatment, and then ensure that it is transferred to a 70-140℃ pre-aging furnace within 2～5min and cooled to 20～40℃ at a cooling rate of 1-15℃/h. And the pre-aging state sample was placed at room temperature for 14 days to stabilize the alloy performance (that is, the T4P(2) state), and finally the T4P(2) state sample was artificially aged at 185°C/20min, and the T4P(2) Tensile properties of as-cast and high-temperature artificially aged alloys (see Table 3 for details).

Table 2 Hardness increment of alloys in different states after aging treatment at 185 °C for 20 min

Table 3 Mechanical properties of alloy plates in T4P(2) state and high temperature artificial aging state

Since the alloy composition, microstructure and heat treatment system all have an influence on the precipitation behavior of the Al-Mg-Si alloy, in order to eliminate the influence of the deformed structure formed in the process of hot working and cold working on the precipitation behavior of the alloy, so as to ensure a better A new type of Al-Mg-Si-Cu-Zn alloy composition with fast aging response was optimized, and the alloys used in different heat treatment states were all taken from ingot samples after homogenization treatment. The hardness changes and corresponding DSC curves of Al-Mg-Si-Cu-Zn alloys in Examples 1-6 after different heat treatment processes are shown in Figures 1-7. It can be seen from Figure 1 that, compared with the 1# alloy not containing Zn, regardless of the 2# alloy not containing Cu or the 5# alloy containing Cu, artificial aging at 185°C for different times is directly carried out after solid solution quenching, and the aging precipitates The speed is faster than that of 1# alloy without Zn, and the peak hardness is also higher than that of 1# alloy. It can be seen from Figure 2 that no matter whether it contains Zn or does not contain Al-Mg-Si alloys, the solution-quenched samples will have a certain degree of hardness increase and finally stabilize when they are placed at room temperature. The 4# alloy with %Zn has a smaller increase. Corresponding DSC analysis of several typical alloys shows that the low-temperature precipitation peak and resolubility peak of Al-Mg-Si-Cu-Zn alloys with a certain amount of Zn added obviously change, especially when the Zn content is added to At 3.0wt%, the precipitation of the β″ phase with a peak temperature of 250 °C shifts significantly forward, indicating that even after natural aging treatment, adding a certain amount of element Zn also has a certain effect on the precipitation of the main strengthening phase—β″ phase. promotion. According to Example 3, if several naturally-aged alloys are subjected to corresponding 185°C high-temperature artificial aging treatment, it can be seen from Figure 4 that the high-temperature aging precipitation rate of the Al-Mg-Si-Cu alloy after adding the element Zn is obvious However, with the change of Zn content, the aging precipitation rate varies greatly, which is mainly due to the influence of the change of the content of each main alloying element on its interaction. Although adding a certain amount of element Zn can speed up the precipitation rate of T4 state alloys during high temperature aging, the precipitation rate is still not ideal. If the invention alloy is subjected to corresponding pre-aging treatment (Example 4), the properties of several alloys are relatively stable during room temperature storage, and similar to the 1# alloy without Zn, there will be no natural aging of the solid solution quenched alloy The phenomenon of hardness increase during the process (as shown in Figure 5), and the DSC analysis of the T4P state sample shows that the low-temperature precipitation peaks all disappear, and after the addition of element Zn, the β″ phase precipitation peak with a peak temperature of 250 ° C also occurs Obvious forward movement. If the pre-aging state alloy plus 14 days of natural aging is placed on the sample for high-temperature artificial aging (embodiment 5), it can be seen from Figure 7 that the high-temperature aging precipitation speed of the alloy after the addition of element Zn is relatively high. A large increase, especially 2#, 3# and 5# alloys, and Zn-containing alloys are easy to precipitate a large number of spherical precipitates under the transmission electron microscope (as shown in Figure 8).

In addition, considering that the new Al-Mg-Si-Cu-Zn alloy with fast aging response characteristics is more suitable for the manufacture of outer plate alloys for automobile bodies, it is possible to further compare the T4 state and T4P state of several alloys at 185 ℃ aging for 20min hardness increment (as shown in Table 2). It can be seen from the table that the 1# alloy in the T4 state has a serious deterioration effect due to natural aging, and even has a decrease in hardness after aging at 185°C/20min, but this phenomenon can be completely avoided after adding element Zn. In addition, for several alloys after the addition of Zn, except for 4# alloy, the hardness increment of several other T4P state alloys after aging at 185°C for 20 minutes is higher than that of the T4P state 1# alloy, especially the hardness increment of the T4P state 1# alloy. The sample after treatment in Example 6 further illustrates that several strengthening phases in the matrix of the new Al-Mg-Si-Cu-Zn alloy can achieve better synergistic precipitation and rapidly strengthen the matrix after being treated by a suitable heat treatment process. According to the above results, some alloys (1# and 5#) were selected for further comparison in Example 7. From Table 3, it can be found that the yield strength increment of 5# alloy is nearly 150MPa after short-time artificial aging treatment at 185℃/20min , this increment is much higher than the increment of about 80MPa for AA6016 and AA6111 alloys commonly used in automobile outer panels.

In summary, the present invention, through compositional design and processing heat treatment process optimization, has carried out very well the interaction between each main alloying element Mg, Si, Cu and Zn in the novel Al-Mg-Si-Cu-Zn series alloy. The alloys in this series have more excellent rapid aging response characteristics than conventional Al-Mg-Si alloys. In addition, the newly developed preparation process can not only accelerate the aging response of the alloy, but also inhibit the natural aging deterioration effect of the solution-quenched Al-Mg-Si alloy, so that the alloy sheet has excellent formability and paint hardening performance. Therefore, the invented alloy and process are not only very suitable for the manufacture of aluminum alloys for lightweight automobile body panels, but also have certain guiding significance for the development, processing and application of new aluminum alloys with fast aging response in other fields. Automobile manufacturers and aluminum alloy companies pay attention to the invention of alloys and related preparation processes, so that they can be promoted and applied in this field as soon as possible.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (9)

1. A method for preparing an Al-Mg-Si-Cu-Zn series aluminum alloy with fast aging response characteristics, the chemical composition and composition of the Al-Mg-Si-Cu-Zn series aluminum alloy with fast aging response characteristics Its mass percent content is: Zn: 3.0-3.7wt%, Mg0.3-1.2wt%, Si0.3-1.2wt%, Cu0.05-0.7wt%, Fe≤0.3wt%, Mn≤0.3wt%, Cr≤0.2wt%, Ti≤0.2wt%, and the balance is Al; it is characterized in that: the preparation method comprises the following steps: Step 1, melting and casting; Step 2, two-stage homogenization; Step 3, hot rolling deformation; Step 4, intermediate annealing; Step five, cold rolling deformation; Step 6, solution treatment above 540°C; Step 7, water quenching treatment; Step eight, multi-level aging treatment. 2. The preparation method of the Al-Mg-Si-Cu-Zn series aluminum alloy with fast aging response characteristics as claimed in claim 1, characterized in that: the Al-Mg-Si-Cu with fast aging response characteristics - The Zn, Si and Cu content ranges of the chemical components of the Zn series aluminum alloy are: Zn3.0-3.5wt%, Si0.8-0.9wt%, Cu0.15-0.35wt%. 3. The preparation method of the Al-Mg-Si-Cu-Zn series aluminum alloy with fast aging response characteristics as claimed in claim 1, characterized in that: the Al-Mg-Si-Cu with fast aging response characteristics - The range of the Mg/Si mass ratio of Mg and Si in the chemical composition of the Zn series aluminum alloy is 0.5-0.67. 4. The method for preparing Al-Mg-Si-Cu-Zn series aluminum alloys with fast aging response characteristics as claimed in any one of claims 1-3, characterized in that: the two-stage homogenization in the second step is specifically It is: start to heat up the alloy sample after smelting and casting from room temperature to 470-485°C at a heating rate of 20-40°C/h and keep it for 2-5 hours, and then continue to heat it up to 545-555°C at a rate of 20-40°C/h. 14~20h, and finally take it out when the temperature is lowered to 100℃ with the furnace at a cooling rate of 20~40℃/h. 5. The method for preparing Al-Mg-Si-Cu-Zn series aluminum alloys with fast aging response characteristics according to any one of claims 1-3, characterized in that: the hot rolling deformation in step 3 is specifically : The starting rolling temperature is 545-555°C, the total deformation of hot rolling is >90%, and the finishing rolling temperature is ≥300°C. 6. The method for preparing Al-Mg-Si-Cu-Zn series aluminum alloys with fast aging response characteristics according to any one of claims 1-3, characterized in that: the intermediate annealing in step 4 is specifically: Put the hot-rolled and deformed alloy sample directly into a heat treatment furnace at 350-450° C. for intermediate annealing for 1-3 hours, and then air-cool. 7. The method for preparing Al-Mg-Si-Cu-Zn series aluminum alloys with fast aging response characteristics as claimed in any one of claims 1-3, characterized in that: the cold rolling deformation of the step five The total rolling deformation is between 50% and 75%, and the pass reduction is between 15% and 25%. 8. The method for preparing Al-Mg-Si-Cu-Zn series aluminum alloys with fast aging response characteristics according to any one of claims 1-3, characterized in that: the solid temperature above 540°C in step 6 Specifically, the solution treatment is: performing solution treatment at 545-555°C/1-6min in a salt bath furnace; the water quenching treatment in step 7 is to directly perform water quenching on the alloy sample after solution treatment. 9. The method for preparing Al-Mg-Si-Cu-Zn series aluminum alloys with fast aging response characteristics as claimed in claim 4, characterized in that: the multi-stage aging treatment in the eighth step is water quenching The alloy sample is transferred to the pre-aging furnace within 2 to 5 minutes for 70-140°C/9-15h pre-aging treatment, then placed at room temperature for 14 days, and finally artificially aged at 185°C; or water quenching The final alloy sample is transferred to a pre-aging furnace at 70-140°C within 2 to 5 minutes, cooled to 20 to 40°C at a cooling rate of 1-15°C/h, taken out, and then placed at room temperature for 14 days, and finally 185°C Artificial aging.