A aging process for improving the impact resistance of aluminum alloy laminated composite plates

Abstract

The invention discloses an aging process for improving the impact resistance of an aluminum alloy laminated composite plate, belonging to the technical field of nonferrous metals. Two laminated composite plates with large differences in Zn and Mg content are rolled to obtain a laminated composite plate with a total thickness of 5.0 mm, wherein the thickness of the Al-7.0Zn-3.0Mg alloy is 4.07 mm, and the thickness of the Al-4.4Zn-2.3Mg alloy is 0.93 mm. The composite plate is then subjected to a uniform solid solution treatment at 470°C / 1h, and further subjected to a uniform aging treatment, wherein the aging process is heat preservation at 105-110°C for 36-60h. The laminated composite plate obtained by the invention has high impact strength and good impact toughness.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous metals and relates to an aging process for improving the impact resistance of an aluminum alloy laminated composite plate. Background Art

[0002] Al-Zn-Mg-Cu alloys are typical heat-treatable strengthening alloys in the aluminum alloy system. The excellent mechanical properties of the alloys depend on the microstructure of the alloys, especially on the formation, growth and coarsening of nano-level strengthening phases. The aging process is a key link in the entire heat treatment system. Conventional aluminum alloy laminated composite panels use a high-strength aluminum alloy as the panel to resist external damage and a medium-strength and high-toughness aluminum alloy as the back panel to absorb and consume external impact energy. Through the design of hard-soft aluminum alloy laminated composite panels and the reasonable proportion of the layered structure, the material protection ability can be maximized while achieving lightweight.

[0003] Aluminum alloy laminated composite plates require the impact-bearing alloy to have high strength and the back aluminum alloy to have high plasticity during the impact resistance process. Laminated plates have higher impact toughness than single high-strength aluminum alloys, and have greater impact strength than single high-toughness aluminum alloys. The combination of impact strength and impact toughness can provide higher impact performance, so the impact resistance of laminated aluminum alloy plates is better than that of single aluminum alloy plates. However, laminated aluminum alloys are made by hot-rolling and compounding two aluminum alloys with different Zn and Mg contents. Conventional laminated plate aging processes can often only make high-strength aluminum alloys have high-strength characteristics, while high-toughness aluminum alloys cannot obtain the best toughness, and it is impossible to achieve both. How to choose an aging process system that comprehensively matches the high strength and high toughness of aluminum alloy laminated composite plates, so that the high-strength aluminum alloy of the impact-resistant main layer meets the high-strength performance and the high-toughness aluminum alloy has high toughness, is a key issue in the application of laminated composite plates.

[0004] Based on the above considerations, the present invention designs an aging system for aluminum alloy laminated composite plates with impact strength and impact toughness superior to those of conventional aging process laminated plates, so that the laminated composite plates have high impact strength and good impact toughness. Summary of the invention

[0005] The purpose of the present invention is to experimentally obtain the optimal aging process system for laminated composite plates as protective plates to resist external impact. Because the laminated aluminum alloy is made of two aluminum alloys with different Zn and Mg contents by hot rolling, it is necessary to find a process range that comprehensively matches high impact strength and high impact toughness to formulate an aging system for the laminated composite plate, so that it can meet the high strength characteristics of the main impact-resistant layer alloy and the high toughness characteristics of the anti-breakdown layer alloy, so as to maximize the impact resistance of the laminated composite plate.

[0006] The present invention realizes an aging process for improving the impact resistance of Al-7.0Zn-3.0Mg and Al-4.4Zn-2.3Mg laminated composite plates through the following technical scheme. The method comprises the following steps: (1) homogenizing high-strength aluminum alloy Al-7.0Zn-3.0Mg (7.0wt% Zn and 3.0wt% Mg) and high-toughness aluminum alloy Al-4.4Zn-2.3Mg (4.4wt% Zn and 2.3wt% Mg), and then performing composite hot rolling to prepare laminated aluminum alloy composite plates; (2) performing uniform solid solution treatment on the laminated aluminum alloy composite plates; (3) performing uniform aging process on the laminated aluminum alloy composite plates after solid solution treatment.

[0007] Step (1), homogenizing the as-cast high-strength aluminum alloy plate Al-7.0Zn-3.0Mg and the as-cast high-toughness aluminum alloy plate Al-4.4Zn-2.3Mg at 470°C / 24h, wherein the thickness of the high-strength aluminum alloy plate after homogenization is 14mm±2mm, and the thickness of the high-toughness aluminum alloy plate is 4mm±1mm, and the two homogenized plates are physically overlapped and rolled into a laminated aluminum alloy composite plate, the rolling is carried out at 440°C, the deformation of the high-strength aluminum alloy plate is 71%±5%, and the deformation of the high-toughness aluminum alloy plate is 76.7%±5%;

[0008] Step (2), subjecting the laminated aluminum alloy composite plate to a uniform solution treatment at a temperature of 470° C. for 1 h, and then to water quenching.

[0009] Step (3), after the solution treatment is completed, the laminated composite plate aluminum alloy is subjected to a unified aging process, the aging temperature range is 100-120°C, the insulation time is 20-60h, and the aging temperature is further preferably 105-110°C, and the insulation time is 36-60h.

[0010] High strain rate compression tests were carried out using a Hopkinson bar.

[0011] The preferred aging process is 105-110℃ / 36-60h, the impact strength of the composite board can reach 808-867MPa, and the impact toughness can reach 252.2-284.4MJ / m 3 Compared with the laminated plate under aging treatment at 120℃ / 24h, the impact strength is increased by 10.6%~14.5%, and the impact toughness is increased by 16.3%~29.0%.

[0012] The present invention designs a unified aging system for the laminated composite plate, so that the laminated composite plate can meet both the high-strength characteristics of the impact high-strength aluminum alloy and the high-toughness characteristics of the high-toughness aluminum alloy, thereby maximizing the impact resistance of the laminated aluminum alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1:SHPB impact performance curve of aluminum alloy laminated composite plate after aging treatment

[0014] Figure 2 Comparison of impact resistance between single alloy and laminated composite plate after aging treatment

[0015] Figure 3 Impact resistance of aluminum alloy laminated composite panels after aging treatment DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with examples, but the present invention is not limited to the following examples.

[0017] Comparative Example 1

[0018] Two Al-Zn-Mg alloys were smelted and cast, wherein the contents of Zn and Mg in the first aluminum alloy were 7.0wt% Zn and 3.0wt% Mg, respectively, and the contents of Zn and Mg in the second aluminum alloy were 4.4wt% Zn and 2.3wt% Mg, respectively, and then homogenized at 470℃ / 24h, and further hot rolled at a hot rolling temperature of 440℃ and a total deformation of 90%, to obtain a laminated composite plate with a total thickness of 5.0mm. The thickness of Al-7.0Zn-3.0Mg alloy is 4.07mm, and the thickness of Al-4.4Zn-2.3Mg alloy is 0.93mm. In addition, 5mm Al-7.0Zn-3.0Mg single alloy plate and 5mm Al-4.4Zn-2.3Mg are prepared by hot rolling. After rolling, the single plate and the laminated composite plate are uniformly solution treated at a solution temperature of 470℃ and a holding time of 1h. Then, conventional peak aging treatment is performed at an aging temperature of 120℃ and a holding time of 24h. After the sample is prepared, a split Hopkinson pressure bar is used at a strain rate of 5000s -1 Impact performance test is carried out under the following conditions to obtain the impact performance reference Figure 1 The specific indicator data are shown in Table 1.

[0019] Table 1 Impact resistance of alloy plates under conventional 120℃ / 24h aging treatment

[0020]

[0021] Example 1

[0022] The laminated composite plate of the comparative example was subjected to a solid solution treatment in the same manner as in comparative example 1, and then subjected to a uniform aging heat treatment, wherein the heat treatment processes were: 105°C / 36h, 105°C / 48h, 105°C / 60h, 110°C / 24h, 110°C / 36h, and 110°C / 48h. After the sample preparation was completed, a split Hopkinson pressure bar was used at a strain rate of 5000s-1 Impact performance test was carried out under the condition of Figure 2 .from Figure 2 It can be seen that under the conventional aging system of 120℃×24h, the maximum impact strength and impact toughness of the laminated board are within the linear superposition range of the impact performance of the two single-layer boards. In order to further improve the impact resistance, the aging process range of the laminated board is further optimized with the goal of simultaneously improving the maximum impact strength and impact toughness by more than 10%. After experiments, it is found that the optimal aging range of the laminated board is aging temperature of 105~110℃ and insulation time of 36~60h. It can be seen that the aging process of 105℃ / 36h, 105℃ / 48h, 105℃ / 60h, and 110℃ / 48h is significantly better than the conventional

[0023] Impact resistance under 120℃ / 24h aging process. Hopkinson impact performance index refer to Table 2, impact performance curve is attached for reference Figure 3 After optimizing the process, the maximum impact strength of the composite board is 808-867MPa, and the impact toughness is 252.2-284.4MJ / m 3 Compared with the conventional aging treatment of the laminate at 120℃ / 24h, the impact strength is increased by 10.6% to 14.5%, and the impact toughness is increased by 16.3% to 29.0%.

[0024] Table 2 SHPB impact properties of laminated composite panels

[0025]

Claims

1. An aging process for improving the impact resistance of Al-7.0Zn-3.0Mg and Al-4.4Zn-2.3Mg laminated composite plates, comprising the following steps: (1) homogenizing the cast high-strength aluminum alloy plate Al-7.0Zn-3.0Mg and the cast high-toughness aluminum alloy plate Al-4.4Zn-2.3Mg at 470°C / 24h, wherein the thickness of the high-strength aluminum alloy plate after homogenization is 14mm±2mm, and the thickness of the high-toughness aluminum alloy plate is The thickness of the two homogenized plates is 4 mm ± 1 mm, and the two plates are physically overlapped and rolled into a laminated aluminum alloy composite plate. The rolling is carried out at 440°C, and the deformation of the high-strength aluminum alloy plate is 71% ± 5%, and the deformation of the high-toughness aluminum alloy plate is 76.7% ± 5%; (2) the laminated aluminum alloy composite plate is uniformly solution treated at a temperature of 470°C for 1 h under a solution treatment process, and then water quenched; (3) the laminated aluminum alloy composite plate after the solution treatment is uniformly subjected to an aging process; After the solution treatment is completed, the laminated composite plate aluminum alloy is subjected to a unified aging process, the aging temperature range is 100 to 120°C, and the insulation time is 20 to 60 hours.

2. The process according to claim 1, characterized in that The aging temperature is 105-110°C and the insulation time is 36-60h.

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