An aluminum alloy strip for a lightweight and high-strength shield and a preparation method thereof

Abstract

The present invention discloses an aluminum alloy strip for a lightweight high-strength shield and a preparation method thereof. Its composition is by mass percentage: Si 0.01 - 0.10%, Fe 0.03 - 0.18%, Cu 0.02 - 0.20%, Mn 0.12 - 0.55%, Mg 5.5 - 6.1%, Cr 0.01 - 0.10%, Zn 0.01 - 0.02% and Ti 0.01 - 0.03%, the balance being Al and unavoidable impurities, and the total content of Cu and Mn elements should not be less than 0.22%. By controlling the hot rolling production process, the cold rolling reduction rate, and the finished product tension leveling process, an aluminum alloy strip for a lightweight high-strength shield with high strength and good formability is obtained, which can replace the existing steel shields and carbon fiber shields, and realize the lightweight and low-cost development of shield products.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-ferrous metals, and particularly relates to an aluminum alloy strip for a lightweight high-strength shield and a preparation method thereof. Background Art

[0002] In the security systems of major public places such as schools, hospitals, communities, apartments, and work units, protective devices such as security guards, protective clothing, and shields are generally equipped, and riot shields are one of them.

[0003] Currently, to meet the usage requirements of shield products, steel or carbon fiber materials are generally used, mainly because of their high strength, which can effectively resist the impact, puncture, strike, machete attack, etc. of foreign objects. However, steel has a large density and weight, which is inconvenient for users to hold for a long time. Carbon fiber has the characteristics of light weight and super strength, which can better avoid the above disadvantages of steel, but carbon fiber belongs to a high molecular synthetic compound, with high production costs and is not easy to recycle and use.

[0004] Using aluminum alloy materials as riot shields has the advantages of light weight, strong impact resistance, durability, the ability to resist projectiles and sharp instruments other than guns and cannons, the ability to prevent acid attacks, and reliable installation and fixation and convenient operation, making it an excellent protective equipment.

[0005] To ensure the realization of the functions of the shield and good appearance quality, the production process of shield products requires processing such as stamping, grinding, baking paint, and drying of the materials used for the shield, and realizing functions such as drilling and adding handles. Therefore, it is necessary to not only ensure the initial strength requirements of the aluminum alloy material used for the shield, but also maintain the stability of the product size and performance during the subsequent processing process. Summary of the Invention

[0006] The purpose of the present invention is to provide an aluminum alloy strip for a lightweight high-strength shield with high strength and high formability and a preparation method thereof in view of the deficiencies of the prior art, so as to replace materials such as stainless steel and carbon fiber, reduce the production cost of products, and facilitate wide application and promotion.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] An aluminum alloy strip for a lightweight high-strength shield and a preparation method thereof, comprising the following steps:

[0009] 1) The chemical composition of the aluminum alloy strip for lightweight high-strength shields, by mass percentage, is as follows: Si 0.01 - 0.10%, Fe 0.03 - 0.18%, Cu 0.02 - 0.20%, Mn 0.12 - 0.55%, Mg 5.5 - 6.1%, Cr 0.01 - 0.10%, Zn 0.01 - 0.02%, and Ti 0.01 - 0.03%. The balance is Al and unavoidable impurities, and the total content of Cu and Mn elements should not be less than 0.22%. Prepare the aluminum alloy ingot according to this chemical composition.

[0010] 2) After sawing and milling the surface of the aluminum alloy ingot, perform homogenization treatment on it. The homogenization temperature is 400 - 500°C. Then arrange hot rolling production. During the production of the last hot rolling pass, the thickness is controlled at 4.8 mm ± 0.5 mm, and the final rolling temperature is controlled above 300°C.

[0011] 3) Subsequently, perform cold rolling production. After cold rolling to 1.75 - 2.20 mm, correct the plate shape through stretch-bending straightening. During the stretch-bending straightening process, control the drying temperature after cleaning at 80 - 150°C, and ensure that the aluminum alloy strip passes through this temperature for no less than 30 s. The straightening elongation rate should not be less than 0.3%.

[0012] The aluminum alloy strip prepared according to the above steps has a tensile strength of more than 450 Mpa, a yield strength of more than 380 Mpa, and can be formed into a shield product through subsequent stamping and meet the relevant requirements of the shield product.

[0013] To ensure the preparation of the aluminum alloy strip for lightweight high-strength shields, in step 1), the Si element content is controlled at 0.01 - 0.10%, and the Fe element content is controlled at 0.03 - 0.18%. If the Si and Fe contents are too low, the production cost is high and it is not conducive to industrialized popularization and use. If the Si and Fe contents are too high, it will affect the forming performance of the material. The Cu element content is controlled at 0.02 - 0.20%, and the Mn element content is controlled at 0.12% - 0.55%. When the Cu and Mn contents are too low, it is not conducive to improving the strength of the material, and it is more difficult to ensure the subsequent baking resistance and puncture resistance of the shield product. When the Cu and Mn contents are too high, the processing performance of the material is poor and it is not conducive to the preparation and production of the material. More importantly, it is necessary to ensure that the total content of Cu and Mn elements should be controlled above 0.22%. This is mainly based on the need to ensure the total production of AL-Cu-Mg and Al-Fe-Mn during the ingot production process, improve the stability of the material, and avoid the phenomenon of strength reduction after long-term storage and use.

[0014] In step 2), during the last pass of hot rolling, the thickness is controlled at 4.8mm±0.5mm, and the final rolling temperature is controlled at above 300℃. In order to ensure the uniformity and stability of the performance of the final product, the final thickness of hot rolling must be within this range to ensure that the strength requirements and forming performance requirements of the final shield product are met. Below this thickness range, the cold rolling processing rate will be insufficient, the tensile and yield strength of the finished product will be low, and further performance will be reduced after baking; above this thickness range, it is difficult to ensure the stability and consistency of the subsequent stamping process, and wrinkling and rebound will occur during the stamping process. In order to ensure the uniformity and stability of the excellent internal structure, the final rolling temperature must be greater than 300℃. Below this temperature, not only will hot rolling production be difficult, but it will also easily lead to problems such as cracked edges and broken belts during the cold rolling process, and there will be large fluctuations in the performance of the final product.

[0015] In step 3), during the bending and straightening process, the drying temperature after cleaning is controlled at 80~150℃, and the aluminum alloy strip is kept at this temperature for no less than 30s, and the straightening elongation should be no less than 0.3%. Only when the strip is kept at this temperature for no less than 30s can the aluminum alloy material maintain the stability of its performance during the shield product processing, especially during the grinding and painting process, and ensure that the strength of the final product meets the requirements. Otherwise, the shield product is prone to performance degradation and scrapping as the use time continues. The straightening elongation should be no less than 0.3% to ensure the stability of the stamping process and avoid stamping wrinkling.

[0016] Only by strictly following the above steps and control methods can we ensure that we can obtain lightweight and high-strength aluminum alloy strips for shields and produce lightweight and low-cost aluminum alloy shield products, making them have great industrial promotion value.

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

[0018] A method for preparing an aluminum alloy strip for a light and high-strength shield is provided. By controlling the composition of the aluminum alloy strip, the hot rolling and cold rolling processes, the drying temperature and the passing time during the stretching, bending and straightening production process, and the elongation of the straightening machine, the shield product can be made light in weight and low in cost, easy to use and promote, and more competitive. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The high-power microscopic image of the internal structure of the aluminum alloy product prepared in Example 1 of the present invention shows the synergistic effect of the Cu and Mn elements. DETAILED DESCRIPTION

[0020] In order to make the above features and advantages of the present invention more clearly understood, the following embodiments are given for detailed description. The methods of the present invention are all conventional methods in the art unless otherwise specified.

[0021] Example 1:

[0022] An aluminum alloy strip for a lightweight high-strength shield and its preparation method, specifically including the following steps:

[0023] 1) Its chemical composition by mass percentage is: Si 0.08%, Fe 0.15%, Cu 0.12%, Mn 0.30%, Mg 5.8%, Cr 0.06%, Zn 0.015% and Ti 0.02%, the balance being Al and unavoidable impurities, and the total content of Cu and Mn elements is 0.42%. Prepare an aluminum alloy ingot according to this chemical composition.

[0024] 2) After sawing and milling the aluminum alloy ingot, perform homogenization treatment on it. The homogenization temperature is 480 °C, and then arrange hot rolling production. During the production of the last hot rolling pass, the thickness is controlled at 4.9 mm, and the final rolling temperature is controlled at 310 °C.

[0025] 3) Subsequently, perform cold rolling production. After cold rolling to 1.98 mm, correct the plate shape through stretch-bending straightening. During the stretch-bending straightening process, control the drying temperature after cleaning at 100 °C, and ensure that the aluminum alloy strip passes through this temperature for 50 s, and the straightening elongation is 0.5%.

[0026] The mechanical properties under this scheme are A1, and the properties after baking at 170 °C for 10 min are A2.

[0027] Comparative Example 2:

[0028] An aluminum alloy strip for a lightweight high-strength shield and its preparation method, specifically including the following steps:

[0029] 1) Its chemical composition by mass percentage is: Si 0.08%, Fe 0.15%, Cu 0.12%, Mn 0.30%, Mg 5.8%, Cr 0.06%, Zn 0.015% and Ti 0.02%, the balance being Al and unavoidable impurities, and the total content of Cu and Mn elements is 0.42%. Prepare an aluminum alloy ingot according to this chemical composition.

[0030] 2) After sawing and milling the aluminum alloy ingot, perform homogenization treatment on it. The homogenization temperature is 480 °C, and then arrange hot rolling production. During the production of the last hot rolling pass, the thickness is controlled at 4.9 mm, and the final rolling temperature is controlled at 310 °C.

[0031] 3) Subsequently, perform cold rolling production. After cold rolling to 1.98 mm, correct the plate shape through stretch-bending straightening. During the stretch-bending straightening process, control the drying temperature after cleaning at 50 °C. To improve production efficiency, the strip passes through this temperature for 15 s, and the straightening elongation is 0.5%.

[0032] The mechanical properties under this scheme are B1, and the properties after baking at 170 °C for 10 min are B2.

[0033] Comparative Example 3:

[0034] An aluminum alloy strip for a lightweight high-strength shield and its preparation method, specifically including the following steps:

[0035] 1) Its chemical composition by mass percentage is: Si 0.08%, Fe 0.15%, Cu 0.01%, Mn 0.19%, Mg 5.8%, Cr 0.06%, Zn 0.015%, and Ti 0.02%, with the balance being Al and unavoidable impurities, and the total content of Cu and Mn elements being 0.20%. Prepare an aluminum alloy ingot according to this chemical composition.

[0036] 2) After sawing and milling the aluminum alloy ingot, perform homogenization treatment on it. The homogenization temperature is 480 °C, and then arrange hot rolling production. During the last pass of hot rolling, control the thickness at 4.9 mm and the final rolling temperature at 310 °C.

[0037] 3) Subsequently, perform cold rolling production. After cold rolling to 1.98 mm, straighten the plate shape through tension leveling. During the tension leveling process, control the drying temperature after cleaning at 100 °C, ensure that the aluminum alloy strip passes through this temperature for 50 s, and the straightening elongation is 0.5%.

[0038] The mechanical properties under this scheme are C1, and the properties after baking at 170 °C for 10 min are C2.

[0039] Comparative Example 4:

[0040] An aluminum alloy strip for a lightweight high-strength shield and its preparation method, specifically including the following steps:

[0041] 1) Its chemical composition by mass percentage is: Si 0.08%, Fe 0.15%, Cu 0.12%, Mn 0.30%, Mg 5.8%, Cr 0.06%, Zn 0.015%, and Ti 0.02%, with the balance being Al and unavoidable impurities, and the total content of Cu and Mn elements being 0.42%. Prepare an aluminum alloy ingot according to this chemical composition.

[0042] 2) After sawing and milling the aluminum alloy ingot, perform homogenization treatment on it. The homogenization temperature is 480 °C, and then arrange hot rolling production. During the last pass of hot rolling, control the thickness at 4.9 mm and the final rolling temperature at 270 °C.

[0043] 3) Subsequently, cold rolling production is carried out. After cold rolling to 1.98 mm, the sheet shape is corrected by tension levelling. During the tension levelling process, the drying temperature after cleaning is controlled at 100 °C, and it is ensured that the aluminium alloy strip passes through this temperature for 50 s, with a levelling elongation of 0.5%.

[0044] The mechanical properties under this scheme are D1, and the properties after baking at 170 °C for 10 min are D2.

[0045] Comparative Example 5:

[0046] An aluminium alloy strip for a lightweight high-strength shield and its preparation method specifically include the following steps:

[0047] 1) Its chemical composition is by mass percentage: Si 0.08%, Fe 0.15%, Cu 0.12%, Mn 0.30%, Mg 5.8%, Cr 0.06%, Zn 0.015% and Ti 0.02%, with the balance being Al and unavoidable impurities, and the total content of Cu and Mn elements being 0.42%. An aluminium alloy ingot is prepared according to this chemical composition.

[0048] 2) After sawing and milling the aluminium alloy ingot, it is subjected to homogenization treatment at a homogenization temperature of 480 °C. Then, hot rolling production is arranged. During the production of the last hot rolling pass, the thickness is controlled at 6.0 mm, and the final rolling temperature is controlled at 310 °C.

[0049] 3) Subsequently, cold rolling production is carried out. After cold rolling to 1.98 mm, the sheet shape is corrected by tension levelling. During the tension levelling process, the drying temperature after cleaning is controlled at 100 °C, and it is ensured that the aluminium alloy strip passes through this temperature for 50 s, with a levelling elongation of 0.5%.

[0050] The mechanical properties under this scheme are E1, and the properties after baking at 170 °C for 10 min are E2.

[0051] Compare the properties before and after baking under different comparative examples as shown in the following table:

[0052]

[0053] Combined with the action principles of each process factor, the results in Table 1 are compared and analyzed.

[0054] In Comparative Example 2, due to insufficient straightening and drying temperature and time, the internal structure is not stable enough. Although the initial performance meets the requirements, the strength decreases significantly after baking. In Comparative Example 3, due to the low content of Cu element and the total content of Cu / Mn, the purpose of improving strength, especially the baking resistance, cannot be achieved, and the initial and baking yield strengths are low. In Comparative Example 4, due to the low finish rolling temperature of hot rolling, the cold rolling work hardening is obvious. The initial strength is high, but the strength decreases more seriously after baking. This is mainly due to the increase in internal energy storage and insufficient baking resistance. In Comparative Example 5, the hot rolling thickness is too thick, and the actual work hardening strength is large, which is similar to the result in Comparative Example 4, and the performance decreases after baking.

[0055] In Example 1, the lightweight high-strength aluminum alloy strip for shields with high initial strength and good baking resistance was obtained by preparing according to this method.

[0056] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A preparation method of an aluminum alloy strip for a light high-strength shield, characterized in that, The chemical composition of the aluminum alloy strip for lightweight high-strength shields is by mass percentage: Si 0.01 - 0.10%, Fe 0.03 - 0.18%, Cu 0.02 - 0.20%, Mn 0.12 - 0.55%, Mg 5.5 - 6.1%, Cr 0.01 - 0.10%, Zn 0.01 - 0.02%, and Ti 0.01 - 0.03%, with the balance being Al and unavoidable impurities, and the total content of Cu and Mn elements being not less than 0.22%; A preparation method of the aluminum alloy strip for lightweight high-strength shields specifically includes the following steps: 1) Prepare an aluminum alloy ingot according to the chemical composition; 2) After sawing and milling the surface of the aluminum alloy ingot, perform homogenization treatment on it. The homogenization temperature is 400 - 500 °C, and then arrange hot rolling production. During the production of the last hot rolling pass, the thickness is controlled at 4.8 mm ± 0.5 mm, and the final rolling temperature is controlled above 300 °C; 3) Subsequently, perform cold rolling production. After cold rolling to 1.75 - 2.20 mm, correct the plate shape through tension leveling. During the tension leveling process, control the drying temperature after cleaning at 80 - 150 °C, and ensure that the aluminum alloy strip passes through this temperature for not less than 30 s, and the leveling elongation is not less than 0.3%.

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