A method for preparing an aluminum alloy composite plate with good strength and plasticity

Abstract

The present invention discloses a method for preparing an aluminum alloy composite plate with good strength and plasticity, which specifically comprises the following steps: (1) performing solid solution treatment on 6082 and 2A14 aluminum alloys to obtain solid solution 6082 and 2A14 aluminum plates; (2) stacking the solid solution 6082 and 2A14 aluminum plates to form a "sandwich structure" laminate; wherein the inner layer of the laminate is a solid solution 2A14 aluminum plate, and the outer layer is a solid solution 6082 aluminum plate; (3) performing hot extrusion composite on the laminate, wherein the width direction of the laminate is parallel to the length direction of the die outlet, the extrusion temperature is 300-400°C, the holding time is 10-15 minutes, the extrusion speed is 5-7 mm / s, and the extrusion deformation is 70-83%; (4) performing annealing and aging treatment on the extruded composite plate; the composite plate after heat treatment not only improves the strength and plasticity of the 6082 aluminum alloy, but also has good corrosion resistance.

Description

Technical Field

[0001] The invention relates to a method for preparing an aluminum alloy composite plate with good strength and plasticity, and belongs to the technical field of aluminum alloy processing. Background Art

[0002] Aluminum alloys, with their advantages of light weight, high specific strength, and excellent processing plasticity, hold broad application prospects in aerospace, automotive, construction, and other fields. Numerous aluminum alloy grades exist, but their properties vary significantly due to differences in material elemental composition, processing methods, and heat treatment methods.

[0003] Some researchers have studied the addition of alloying elements (such as Er, Zr, Y, and Sc) to aluminum alloys to improve their strength by refining grains and introducing lattice distortion. However, numerous studies have shown that simply controlling defects often results in increased strength but decreased plasticity. Furthermore, due to differences in smelting processes and material purity, the resulting new alloys exhibit poor stability. Currently, these efforts are still in the laboratory research stage and cannot be achieved in large-scale industrial production.

[0004] 6082 and 2A14 aluminum alloys both belong to the aluminum alloy system that can be heat-treated and strengthened. Among them, 6082 aluminum alloy is mainly composed of elements such as Al, Mg, and Si, and the main strengthening phase is Mg2Si. It has moderate strong plasticity and good corrosion resistance and is mainly used in construction, automobiles, ships and other fields; 2A14 is mainly composed of elements such as Al, Cu, and Mg, and the main strengthening phase is Al2Cu. It has excellent strong plasticity and is mainly used in aerospace and other fields. Due to the different alloy systems, the precipitation temperatures of their respective strengthening phases also have certain differences. Therefore, the heat treatment process of 6082 / 2A14 / 6082 composite plates will have a crucial impact on the performance of layered composite materials; the present invention is based on an extrusion process and adopts a suitable heat treatment process to develop a preparation process for aluminum alloy composite plates, and obtains 6082 / 2A14 / 6082 composite plates with excellent performance. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing an aluminum alloy composite plate with good strength and plasticity, which specifically comprises the following steps:

[0006] (1) Solution treatment of 6082 and 2A14 aluminum plates can dissolve the alloy elements in the plates into the matrix, thereby forming a supersaturated solid solution in the system to achieve the effect of homogenization treatment. After quenching, solid solution 6082 and 2A14 aluminum plates are obtained.

[0007] (2) Solid solution 6082 and 2A14 aluminum sheets are stacked to form a "sandwich structure" laminate, wherein the inner layer of the laminate is solid solution 2A14 aluminum sheet and the outer layer is solid solution 6082 aluminum sheet.

[0008] (3) The laminate is subjected to hot extrusion compounding, wherein the width direction of the laminate is parallel to the length direction of the die outlet, the extrusion temperature is 300-400°C, the holding time is 10-20 min, the extrusion speed is 5-8 mm / s, and the extrusion deformation is 70-83%, which can ensure that the solid solution state 6082 and 2A14 aluminum plates have good processing and formability.

[0009] (4) Annealing and aging treatment are performed on the extruded composite plate.

[0010] Preferably, the solution temperature of the solution treatment in step (1) of the present invention is 500-530° C., the solution time is 1-4 h, and the quenching is carried out at room temperature (10-30° C.).

[0011] Preferably, the solution temperature of the solution treatment in step (1) of the present invention is 500-530° C., and the solution time is 1-4 hours.

[0012] Preferably, in step (1) of the present invention, the thickness ratio of the solid solution 6082 aluminum plate to the 2A14 aluminum plate is 1 to 4:1.

[0013] Preferably, the pretreatment in step (1) of the present invention is: polishing the solid solution 6082 and 2A14 aluminum plates on 600-mesh sandpaper, and then cleaning them in an ultrasonic cleaning machine filled with anhydrous ethanol for 5 to 10 minutes to remove the oxide layer and oil stains on the surface of the sample; then using a hair dryer to blow dry the surface of the solid solution 6082 and 2A14 aluminum plates and set them aside.

[0014] Preferably, after the laminate is extruded and compounded in step (4) of the present invention, the thickness ratio of the 6082 aluminum plate to the 2A14 aluminum plate is 1 to 4:1.

[0015] Preferably, in step (4) of the present invention, the annealing temperature is 500-530° C., the annealing time is 1-4 h, and then water quenching is performed at room temperature, the aging temperature is 150-180° C., and the aging time is 6-24 h.

[0016] Another object of the present invention is to provide a 6082 / 2A14 / 6082 aluminum alloy composite plate with good strength and plasticity obtained by the preparation method.

[0017] The beneficial effects of the present invention are:

[0018] (1) The 6082 / 2A14 / 6082 composite plate produced by the present invention achieves improved performance while the outer layer is protected by the more corrosion-resistant 6082 layer, resulting in the composite plate having excellent corrosion resistance. It can be used in fields requiring both strength and corrosion resistance.

[0019] (2) The interface of the composite plate produced by the present invention achieves metallurgical bonding, indicating that the extrusion process parameters are good and can achieve excellent composite effect; in addition, the heat treatment system can achieve good strengthening effect of the composite plate.

[0020] (3) The composite plate of the present invention is composed of two heat-treatable and strengthenable aluminum alloys with different alloy systems. Therefore, setting reasonable heat treatment parameters can avoid over-aging or under-aging of a certain layer of the composite plate, thereby failing to achieve good strength and plasticity of the composite plate; finally, by adjusting the layer thickness ratio of 6082 and 2A14 layers during extrusion composite, composite plates that meet the requirements of different working conditions can be prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the extrusion composite process of the 6082 / 2A14 / 6082 aluminum alloy composite plate of the present invention.

[0022] Figure 2 Macroscopic morphologies of 6082 / 2A14 / 6082 aluminum alloy composite plates in extruded, aged, and solution-aged states when the 6082 and 2A14 layer thickness ratio of the present invention is 1:1, Comparative Example 1 (E1), Comparative Example 2 (E2), and Example 1 (E3).

[0023] Figure 3 Grain boundary diagrams of 6082 / 2A14 / 6082 aluminum alloy composite plates in extruded, aged, and solution-aged states when the 6082 and 2A14 layer thickness ratio of the present invention is 1:1, Comparative Example 1 (E1), Comparative Example 2 (E2), and Example 1 (E3).

[0024] Figure 4 Matrix hardness diagrams of the 6082 / 2A14 / 6082 aluminum alloy composite plates in extruded, aged, and solution-aged states when the 6082 and 2A14 layer thickness ratio of the present invention is 1:1, (a) macroscopic matrix hardness test diagram; (b) hardness diagram of the extruded 6082 / 2A14 / 6082 aluminum alloy composite plate of Comparative Example 1; hardness diagram of the aged (E2) 6082 / 2A14 / 6082 aluminum alloy composite plate of Comparative Example 2; hardness diagram of the solution-aged (E3) 6082 / 2A14 / 6082 aluminum alloy composite plate of Example 1. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0026] Example 1

[0027] A method for improving the strength and plasticity of 6082 aluminum plate, comprising the following steps:

[0028] (1) The initially 4 mm thick rolled 6082 and 2A14 aluminum sheets were cut into 45 mm × 16 mm sheets. The cut 6082 and 2A14 aluminum sheets were then solution treated at 500 °C for 4 h to remove residual stress and allow the second phase to fully dissolve back into the matrix, and then water quenched at room temperature. The solution-treated 6082 and 2A14 aluminum sheets were then polished on 600 grit sandpaper and then cleaned in an ultrasonic cleaner filled with anhydrous ethanol for 5 min to remove the oxide layer and oil stains on the surface of the samples. Finally, the surface of the solution-treated 6082 and 2A14 aluminum sheets was blown dry with a hair dryer and set aside.

[0029] (2) Two 4mm thick solid solution 6082 aluminum plates and two 4mm thick solid solution 2A14 aluminum plates are stacked to form a "sandwich structure" laminate. The inner layer of the laminate is a solid solution 2A14 aluminum plate, and the outer layer is a solid solution 6082 aluminum plate. The width direction of the stacked laminate is parallel to the length direction of the mold outlet. The inner layer of the laminate is a solid solution 2A14 aluminum plate, and the outer layer is a solid solution 6082 aluminum plate. The total thickness of the stacked laminate is about 16mm. Figure 1 The extrusion die shown compounds the laminate.

[0030] (3) Before extrusion, the extrusion inner mold is first sprayed with graphite liquid for lubrication. When spraying, the graphite liquid needs to be evenly sprayed around the inner mold; then the mold is preheated at a temperature of 400°C. After the temperature stabilizes, the laminate is placed in the mold and kept warm for 10 minutes; then the laminate is extruded and composited at an extrusion speed of 5 mm / s and an extrusion deformation of 82%, obtaining a 6082 / 2A14 / 6082 composite plate with a thickness of about 3 mm.

[0031] (4) The extruded composite plate was annealed and aged at a temperature of 505°C for 2 h, and then water quenched at room temperature at a temperature of 160°C for 12 h.

[0032] The 6082 / 2A14 / 6082 composite plate prepared in this embodiment has a yield strength of 290 MPa, a tensile strength of 390 MPa, and an elongation at break of 23.4% at room temperature.

[0033] Depend on Figure 3It can be seen from Figure E3 that the 6082 / 2A14 / 6082 composite plate treated with solution aging (SS+A8) has a greater driving force for recrystallization due to its higher solution temperature and longer holding time. At the same time, the second phase in the organization can be fully melted back into the matrix, indicating that the pinning effect of the precipitation on the grain boundary is significantly weakened, which greatly improves the movement activity of the grain boundary. At a higher temperature, the recrystallized grains are prone to grain boundary migration, which causes the grains to swallow each other and grow. In addition, the 6082 in the composite plate There is a certain difference in the grain boundary movement activity between the 2A14 side and the 6082 side, resulting in the composite plate treated with SS+A8 showing a double-peak grain feature consisting of coarse grains on the 6082 side and fine grains on the 2A14 side, which in turn produces additional strengthening and work hardening effects; Moreover, after solution treatment, supersaturated solid solutions are formed on both the 6082 side and the 2A14 side of the composite plate. During the subsequent aging treatment, the precipitation behavior of the two layers is also significantly different due to the difference in alloy systems, resulting in a significant difference in hardness between the inner and outer layers; Figure 4 As shown in the results, the matrix hardness of the extruded (E1), aged (E2), and solution-aged (E3) composite plates exhibits a trend of high in the center and low on both sides, further suggesting that the composite plates possess properties different from those of conventional plates. The hardness distribution of the extruded and aged composite plates is essentially the same; however, the composite plates treated with solution-aging exhibit a significant increase in hardness due to the precipitation of a large amount of second phase within their microstructure. Tensile test results reveal significant pinning of dislocations by the second phase, and a significant coordination effect between the coarse and fine grains (between the soft and hard layers). Ultimately, the solution-aged 6082 / 2A14 / 6082 composite plates demonstrates the superior performance of synergistically improved strength and ductility.

[0034] Example 2

[0035] A method for improving the strength and plasticity of 6082 aluminum plate, comprising the following steps:

[0036] (1) The initially 4 mm thick rolled 6082 and 2A14 aluminum sheets were cut into 45 mm × 16 mm sheets. The cut 6082 and 2A14 aluminum sheets were then solution treated at 510 °C for 2 h to remove residual stress and allow the second phase to fully dissolve back into the matrix, and then water quenched at room temperature. The solution-treated 6082 and 2A14 aluminum sheets were then polished on 600 grit sandpaper and then cleaned in an ultrasonic cleaner filled with anhydrous ethanol for 10 min to remove the oxide layer and oil stains on the surface of the samples. Finally, the surface of the solution-treated 6082 and 2A14 aluminum sheets was blown dry with a hair dryer and set aside.

[0037] (2) Two 4mm thick solid solution 6082 aluminum plates and two 4mm thick solid solution 2A14 aluminum plates are stacked to form a "sandwich structure" laminate. The inner layer of the laminate is a solid solution 2A14 aluminum plate, and the outer layer is a solid solution 6082 aluminum plate. The width direction of the stacked laminate is parallel to the length direction of the mold outlet. The inner layer of the laminate is a solid solution 2A14 aluminum plate, and the outer layer is a solid solution 6082 aluminum plate. The total thickness of the stacked laminate is about 16mm. Figure 1 The extrusion die shown compounds the laminate.

[0038] (3) Before extrusion, the extrusion inner mold is first sprayed with graphite liquid for lubrication. When spraying, the graphite liquid needs to be evenly sprayed around the inner mold; then the mold is preheated at a temperature of 350°C. After the temperature stabilizes, the laminate is placed in the mold and kept warm for 20 minutes; then the laminate is extruded and composited at an extrusion speed of 6 mm / s and an extrusion deformation of 70%, obtaining a 6082 / 2A14 / 6082 composite plate with a thickness of about 3 mm.

[0039] (4) The extruded composite plate was annealed and aged at a temperature of 530°C for 4 h, and then water quenched at room temperature at a temperature of 180°C for 6 h.

[0040] The 6082 / 2A14 / 6082 composite plate prepared in this embodiment has a yield strength of 284 MPa, a tensile strength of 375 MPa, and an elongation at break of 21.4% at room temperature.

[0041] Example 3

[0042] A method for improving the strength and plasticity of 6082 aluminum plate, comprising the following steps:

[0043] (1) The initially 4.0 mm thick rolled 6082 and 2A14 aluminum sheets were cut into 45 mm × 16 mm sheets. The cut 6082 and 2A14 aluminum sheets were then solution treated at 530 °C for 1 h to remove residual stress and allow the second phase to fully dissolve back into the matrix, and then water quenched at room temperature. The solution-treated 6082 and 2A14 aluminum sheets were then polished on 600-grit sandpaper and then cleaned in an ultrasonic cleaner filled with anhydrous ethanol for 8 min to remove the oxide layer and oil stains on the sample surface. Finally, the surface of the solution-treated 6082 and 2A14 aluminum sheets was blown dry with a hair dryer and set aside.

[0044] (2) Two 4mm thick solid solution 6082 aluminum plates and two 4mm thick solid solution 2A14 aluminum plates are stacked into a "sandwich structure" laminate, the inner layer of the laminate is the solid solution 2A14 aluminum plate, and the outer layer is the solid solution 6082 aluminum plate; the width direction of the stacked laminate is parallel to the length direction of the mold outlet, the inner layer of the laminate is the solid solution 2A14 aluminum plate, and the outer layer is the solid solution 6082 aluminum plate, and the total thickness of the stacked laminate is about 16mm; using Figure 1 The extrusion die shown compounds the laminate.

[0045] (3) Before extrusion, the extrusion inner mold is first sprayed with graphite liquid for lubrication. When spraying, the graphite liquid needs to be evenly sprayed around the inner mold; then the mold is preheated at a temperature of 300°C. After the temperature stabilizes, the laminate is placed in the mold and kept warm for 15 minutes; then the laminate is extruded and composited at an extrusion speed of 8 mm / s and an extrusion deformation of 78%, obtaining a 6082 / 2A14 / 6082 composite plate with a thickness of about 3 mm.

[0046] (4) The extruded composite plate was annealed and aged at 520°C for 3 h, and then water quenched at room temperature at 150°C for 24 h.

[0047] The 6082 / 2A14 / 6082 composite plate prepared in this embodiment has a yield strength of 271 MPa, a tensile strength of 369 MPa, and an elongation at break of 22.8% at room temperature.

[0048] Comparative Example 1

[0049] Compared with Example 1, this embodiment has the same specific steps and parameters, except that the extruded composite plate is not subjected to annealing and aging treatment.

[0050] The extruded 6082 / 2A14 / 6082 composite plate was air-cooled at room temperature; the resulting sample had a yield strength of 122 MPa, a tensile strength of 216 MPa, and an elongation at break of 15.6% at room temperature.

[0051] pass Figure 1 Comparison of E1 and E3 shows that, compared with Example 1, due to the smaller grain size of the extruded 6082 / 2A14 / 6082 composite plate, a large number of dislocations remain in its structure during the extrusion and composite process; and the number of dislocations that can be accommodated in the grains is certain. During the subsequent tensile process, the dislocations further proliferate and entangle, resulting in earlier stress concentration in the grains, thereby affecting their elongation; and the limited second phase in the grains also shows that its ability to pin grain boundaries and hinder dislocation movement is low, thus exhibiting poor strength.

[0052] Comparative Example 2

[0053] Compared with Example 1, this embodiment has the same specific steps and parameters, except that the extruded composite plate is subjected to aging treatment but not annealing treatment.

[0054] The extruded 6082 / 2A14 / 6082 composite plate was air-cooled at room temperature; the resulting sample had a yield strength of 131 MPa, a tensile strength of 234 MPa, and an elongation at break of 16.3% at room temperature.

[0055] By comparison Figure 3 The differences between E2, E1, and E3 indicate that the grain size of the plate treated with aging (A8) is not significantly different from that of the extruded 6082 / 2A14 / 6082 composite plate, but still shows significant differences from the solution-aged 6082 / 2A14 / 6082 composite plate. This suggests that the lower aging temperature does not provide sufficient energy for grain boundaries to migrate across potential barriers, resulting in a large number of residual dislocations remaining in the microstructure. However, despite the significant difference between the aging temperature and the recrystallization temperature, it can still reduce the dislocation density within the microstructure to a certain extent, accompanied by a certain amount of second phase precipitation. Therefore, the aged 6082 / 2A14 / 6082 composite plate shows a slight improvement in hardness and mechanical properties.

[0056] Comparative Example 3

[0057] Compared with Example 1, the specific steps and parameters of this embodiment are the same, except that only solid solution 6082 aluminum plates are used, that is, the inner and outer layers of the prepared laminate are both 6082 aluminum plates, a 6082 / 6082 / 6082 composite plate.

[0058] The composite plate obtained in this embodiment has a yield strength of 244 MPa, a tensile strength of 289 MPa, and an elongation at break of 11.0% at room temperature.

[0059] By comparison with Example 1, it can be seen that the composite plate prepared using only a single solid solution state 6082 plate only shows the effect of interface strengthening in the system, and the effect of interface strengthening is limited and insufficient to significantly improve its mechanical properties.

[0060] Comparative Example 4

[0061] Compared with Example 1, this embodiment has the same specific steps and parameters, except that only solid solution 2A14 aluminum plates are used, that is, the inner and outer layers of the prepared laminate are both 2A14 aluminum plates, and the composite plate is 2A14 / 2A14 / 2A14.

[0062] The composite plate obtained in this embodiment has a yield strength of 282 MPa, a tensile strength of 450 MPa, and an elongation at break of 29.1% at room temperature.

[0063] Comparison with Example 1 shows that the 2A14 plate after solution aging treatment exhibits the best mechanical properties, with both high tensile strength and good elongation at break. This shows that the 2A14 layer contributes significantly to the strength and plasticity of the 6082 / 2A14 / 6082 composite plate.

[0064] The results of Example 1, Comparative Examples 3, and Comparative Examples 4 show that the composite plate produced by stacking using a "sandwich structure" has excellent mechanical properties, significantly improving the mechanical properties of 6082 plates. By adding an aluminum alloy plate (hard layer) with excellent strength and plasticity for extrusion lamination, the composite plate produced, after undergoing appropriate heat treatment, has significant heterogeneous structural differences and second-phase strengthening differences between the soft and hard layers, which can greatly improve the strength and plasticity of the 6082 plate. Figure 2 The results show that although aluminum alloys with different chemical compositions were used for extrusion composite, they belonged to the same aluminum alloy sequence; the interface of the composite plate was well bonded, and no cracking or other defects affecting the mechanical properties of the plate were observed.

[0065] Comparative Example 5

[0066] Compared with Example 1, this embodiment has the same specific steps and parameters, except that: solid solution 6082 and 2A14 aluminum plates are used without surface treatment.

[0067] The composite plate obtained in this embodiment has a yield strength of 260 MPa, a tensile strength of 350 MPa, and an elongation at break of 16.3% at room temperature.

[0068] Comparison with Example 1 shows that for untreated solid solution 6082 and 2A14 sheets, the surface oxide scale and oil contamination during extrusion will inevitably affect the interfacial bonding of the composite sheet. Defects at the interface will inevitably lead to significant stress concentration during subsequent tensile testing, causing premature cracking and interfacial cracking in the composite sheet, severely impacting the composite sheet's composite quality and resulting in poor mechanical properties.

[0069] It can be seen that the present invention compounds two heat-treatable and strengthened 6082 and 2A14 aluminum plates through an extrusion process or a rolling process, and achieves excellent strength and plasticity through subsequent heat treatment.

[0070] Finally, it should be noted that the above embodiments only use 6082 and 2A14 aluminum alloys as examples to illustrate the technical solution of the present invention. Although the present invention has been described in detail through the above preferred embodiments, it should be noted that the solution is applicable to other series of aluminum alloy extruded plates or rolled plates by changing relevant process parameters, such as layer thickness ratio, extrusion ratio, multi-stage aging treatment process, etc.; those skilled in the art should understand that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum alloy composite plate with good strength and plasticity, characterized in that: The specific steps include: (1) Solution treatment is performed on 6082 and 2A14 aluminum plates, and solid solution 6082 and 2A14 aluminum plates are obtained after quenching; and then the surface of the solid solution aluminum plates is pretreated for standby use; (2) Two solid solution 6082 aluminum plates and two 2A14 aluminum plates are stacked to form a "sandwich structure" laminate; wherein the inner layer of the laminate is the solid solution 2A14 aluminum plate and the outer layer is the solid solution 6082 aluminum plate; (3) The laminate is hot extruded, wherein the width direction of the laminate is parallel to the length direction of the die outlet, the extrusion temperature is 300-400 °C, the holding time is 10-20 min, the extrusion speed is 5-8 mm / s, and the extrusion deformation is 70-83%; (4) Annealing and aging treatment of the extruded composite plate; In the step (4), the annealing temperature is 500-530°C, the annealing time is 1-4 h, and then the steel is water quenched at room temperature, the aging temperature is 150-180°C, and the aging time is 6-24 h.

2. The method for preparing an aluminum alloy composite plate with good strength and plasticity according to claim 1, wherein: The solution treatment temperature in step (1) is 500-530°C, and the solution treatment time is 1-4 h.

3. The method for preparing an aluminum alloy composite plate with good strength and plasticity according to claim 1, wherein: In step (1), the thickness ratio of the solid solution 6082 aluminum plate and the 2A14 aluminum plate is 1 to 4:

1.

4. The method for preparing an aluminum alloy composite plate with good strength and plasticity according to claim 1, wherein: The pretreatment in step (1) is as follows: the solid solution 6082 and 2A14 aluminum plates are polished on 600-grit sandpaper, and then cleaned in an ultrasonic cleaning machine filled with anhydrous ethanol for 5 to 10 minutes to remove the oxide layer and oil stains on the surface of the sample; then the surface of the solid solution 6082 and 2A14 aluminum plates are blown dry with a hair dryer and set aside.

5. The method for preparing an aluminum alloy composite plate with good strength and plasticity according to claim 1, wherein: After the laminate is extruded and laminated in step (4), the thickness ratio of the 6082 aluminum plate to the 2A14 aluminum plate is 1 to 4:

1.

6. A 6082 / 2A14 / 6082 aluminum alloy composite plate having good strength and plasticity, prepared by the preparation method according to any one of claims 1 to 5.

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