Aluminum alloy for improving pedestrian protection performance, and preparation method and use thereof

Abstract

The present application relates to a kind of aluminum alloy and its preparation method and purposes of improving pedestrian protection performance, the aluminum alloy of improving pedestrian protection performance includes by mass percentage:Si 0.45-0.7%, Mn 0.05-0.15%, Mg 0.45-0.65%, Fe≤0.1%, Cu≤0.1%, Cr≤0.04%, Zn≤0.1%, Ti≤0.1%, impurity element≤0.15%, the balance is Al;The temperature and time of preparation in solid solution treatment satisfy: t (min) =0.0013×Tc 2 -1.4305×Tc+400.29.The aluminum alloy provided by the present application, by adjusting the formula of aluminum alloy, by adopting specific solid solution treatment system, in the case of reducing the yield strength of the obtained aluminum alloy, the elongation of the aluminum alloy is ensured, to ensure that the aluminum alloy meets the requirements when used as automobile sheet.

Description

Technical Field

[0001] This invention relates to the field of vehicle body materials technology, specifically to an aluminum alloy that improves pedestrian protection performance, its preparation method, and its applications. Background Technology

[0002] Currently, the main aluminum alloy sheets used in automotive bodies are 2-series, 5-series, and 6-series. Compared to 2-series and 5-series aluminum alloys, 6-series aluminum alloys have better corrosion resistance and paint hardening properties, making them the mainstream choice for automotive aluminum alloy sheets. For the inner panels of body panels, the most commonly used 6-series aluminum alloy is 6016 aluminum alloy, which has good formability. 6016 aluminum alloy exhibits low yield strength after solution treatment and water quenching, good stamping performance, and its strength is further enhanced during subsequent paint baking. Its excellent stamping formability and strong paint hardening ability perfectly meet the requirements of automotive body sheets.

[0003] For example, CN108385043A discloses a method for preparing 6016 aluminum alloy sheet for automobile body, including the following steps: (1) preparing 6016 aluminum alloy ingot; (2) heating the 6016 aluminum alloy ingot to 440-490℃ and hot rolling it to obtain a hot-rolled sheet; (3) keeping the hot-rolled sheet at 470-550℃ for 2-6 hours and then furnace cooling it to room temperature; (4) cold rolling it to obtain a cold-rolled sheet; (5) performing solution treatment; (6) placing it at room temperature for 5-30 minutes; (7) performing pre-aging treatment; (8) placing the pre-aged sheet at room temperature for more than 4 weeks.

[0004] However, with the continuous upgrading of automotive collision regulations, the requirements for pedestrian protection performance of vehicles are constantly increasing, demanding further reductions in injury values ​​at each impact point. Therefore, continuing to use the currently commonly used 6016 aluminum sheet would significantly increase the complexity of component structural design and front engine compartment layout to meet collision regulations, and in some cases, might ultimately fail to meet the requirements. Consequently, the automotive industry has raised requirements for improved pedestrian protection performance of automotive body panels, especially the inner panel of the hood.

[0005] Improving pedestrian protection performance requires that, upon a collision between a vehicle and a pedestrian, the aluminum alloy automotive sheet should yield quickly without breaking. This necessitates a further reduction in the material's yield strength and a further increase in its elongation, thereby enhancing the pedestrian protection effect of the components. However, existing 6016 series aluminum alloys have relatively high yield strength, which is not conducive to rapid yielding for pedestrian protection. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide an aluminum alloy with improved pedestrian protection performance, its preparation method and application, so as to solve the problem that the current 6016 series aluminum alloy has a high yield strength, which is not conducive to rapid yielding and thus protecting pedestrians.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] This invention provides an aluminum alloy for improving pedestrian protection performance, wherein the aluminum alloy for improving pedestrian protection performance comprises, by weight percentage:

[0009] Si 0.45-0.7%, Mn 0.05-0.15%, Mg 0.45-0.65%, Fe≤0.1%, Cu≤0.1%, Cr≤0.04%, Zn≤0.1%, Ti≤0.1%, impurity elements≤0.15%, balance Al;

[0010] The solution treatment temperature and time in the preparation of the aluminum alloy to improve pedestrian protection performance satisfy: t = 0.0013 × Tc 2 -1.4305×Tc+400.29.

[0011] The aluminum alloy provided by this invention, which improves pedestrian protection performance, combines adjustments to the aluminum alloy formula with a specific solution treatment process. This reduces the yield strength of the resulting aluminum alloy while ensuring its elongation, thus ensuring that the aluminum alloy meets requirements when used as automotive sheet metal.

[0012] As a preferred embodiment of the present invention, the aluminum alloy for improving pedestrian protection performance comprises, by weight percentage:

[0013] Si 0.5-0.6%, Mn 0.08-0.1%, Mg 0.5-0.6%, Fe≤0.1%, Cu≤0.1%, Cr≤0.04%, Zn≤0.1%, Ti≤0.1%, impurity elements≤0.15%, balance Al.

[0014] In a second aspect, the present invention provides a method for preparing an aluminum alloy with improved pedestrian protection performance as described in the first aspect, the method comprising:

[0015] According to the formula, after batching, an aluminum alloy ingot with improved pedestrian protection performance is obtained by semi-continuous casting process. Then, it is subjected to hot rolling, annealing, cold rolling, solution treatment, aging treatment and room temperature standing in sequence to obtain an aluminum alloy with improved pedestrian protection performance.

[0016] As a preferred technical solution of the present invention, the hot rolling is started after the aluminum alloy ingot is held at 435-475℃ for 3-7 hours.

[0017] Preferably, the thickness of the hot-rolled sheet is 3-5 mm.

[0018] As a preferred embodiment of the present invention, the annealing temperature is 460-490℃.

[0019] Preferably, the annealing holding time is 1.5-5 hours.

[0020] As a preferred technical solution of the present invention, the sheet obtained after annealing is cold rolled after being cooled in the furnace.

[0021] Preferably, the thickness of the cold-rolled sheet is 0.7-1.3 mm.

[0022] As a preferred technical solution of the present invention, the solution treatment temperature Tc is 470-550℃.

[0023] Preferably, the solution treatment time t is 3-13 min.

[0024] Preferably, the temperature and time of the solution treatment satisfy: t = 0.0013 × Tc 2 -1.4305×Tc+400.29.

[0025] As a preferred technical solution of the present invention, the aging treatment temperature is 150-175℃.

[0026] Preferably, the aging process takes 1-6 minutes.

[0027] As a preferred embodiment of the present invention, the room temperature for resting is ≤40℃.

[0028] Preferably, the time for standing at room temperature is ≥72 hours.

[0029] Thirdly, the present invention provides an use of an aluminum alloy for improving pedestrian protection performance as described in the first aspect, the use including the use of the aluminum alloy for improving pedestrian protection performance to manufacture an inner panel of a car hood.

[0030] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0031] (1) This invention achieves a certain amount of orderly precipitation of Mg2Si phase rather than complete precipitation by strictly controlling the content of Si and Mg elements in 6-series aluminum alloys, thereby reducing the yield strength to a certain extent.

[0032] (2) By processing the aluminum plate according to the temperature and time parameters determined by the formula for the relationship between solution temperature and solution time proposed in this invention, the aluminum plate can be made to have a lower yield strength while ensuring that the original plasticity is not reduced. This is because in the solution treatment process, a higher solution temperature and a longer solution time allow the solid solute in the solid solution to be fully dissolved in the α matrix, resulting in higher mechanical properties. However, too low a solution temperature and too short a solution time will result in too much solid solute remaining undissolved, leading to a deterioration in the strength, hardness and elongation of the aluminum plate.

[0033] (3) The performance indicators of the aluminum plate for improving pedestrian protection performance of the vehicle body inner panel obtained by the present invention are: R p0.2 ≥65MPa, R m ≥132MPa, A 80mm ≥23.5%, n 4～6 ≥0.29, r 8～12 ≥0.64; The performance index after paint baking treatment is: R p0.2 ≥113MPa, R m ≥175MPa, A 80mm ≥16%.

[0034] (4) The car hood assembly made of aluminum plate with improved pedestrian protection performance for the inner body panel provided by the present invention was subjected to a pedestrian head impact test. The injury values ​​at each collision point were extracted, summarized and scored. The results showed that after using the aluminum plate with improved pedestrian protection performance for the inner body panel, the pedestrian head injury value was generally significantly reduced. The pedestrian protection score was calculated to show that the pedestrian protection effect was 31.25% higher than that of the traditional 6016 aluminum plate. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the distribution of head injuries to pedestrians obtained in Embodiment 1 of the present invention;

[0036] Figure 2 This is a schematic diagram of the distribution of head injuries to pedestrians obtained from Comparative Example 1 of the present invention.

[0037] In the diagram: 1-Red, 2-Yellow, 3-Green.

[0038] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0039] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0040] This embodiment provides an aluminum alloy for improving pedestrian protection performance, wherein the aluminum alloy for improving pedestrian protection performance comprises, by weight percentage:

[0041] Si 0.45-0.7%, Mn 0.05-0.15%, Mg 0.45-0.65%, Fe≤0.1%, Cu≤0.1%, Cr≤0.04%, Zn≤0.1%, Ti≤0.1%, impurity elements≤0.15%, balance Al.

[0042] In this invention, the Si content in the aluminum alloy that improves pedestrian protection performance is 0.45-0.7% by mass, for example, it can be 0.45%, 0.5%, 0.55%, 0.6%, 0.65% or 0.7%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0043] In this invention, the Mn content in the aluminum alloy that improves pedestrian protection performance is 0.05-0.15% by mass, for example, it can be 0.05%, 0.06%, 0.08%, 0.1%, 0.12%, 0.14% or 0.15%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0044] In this invention, the Mg content in the aluminum alloy that improves pedestrian protection performance is 0.45-0.65% by mass, for example, it can be 0.45%, 0.5%, 0.55%, 0.6% or 0.65%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0045] In this invention, the Fe content in the aluminum alloy that improves pedestrian protection performance is ≤0.1% by mass, for example, it can be 0.1%, 0.08%, 0.06%, 0.04%, 0.02% or 0.01%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0046] In this invention, the Cu content in the aluminum alloy that improves pedestrian protection performance is ≤0.1% by mass, for example, it can be 0.1%, 0.08%, 0.06%, 0.04%, 0.02% or 0.01%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0047] In this invention, the Cr content in the aluminum alloy that improves pedestrian protection performance is ≤0.04% by mass, for example, it can be 0.04%, 0.03%, 0.02% or 0.01%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0048] In this invention, the Zn content in the aluminum alloy that improves pedestrian protection performance is ≤0.1% by mass, for example, it can be 0.1%, 0.08%, 0.06%, 0.04%, 0.02% or 0.01%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0049] In this invention, the Ti content in the aluminum alloy that improves pedestrian protection performance is ≤0.1% by mass, for example, it can be 0.1%, 0.08%, 0.06%, 0.04%, 0.02% or 0.01%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0050] In this invention, the impurity elements in the aluminum alloy that improves pedestrian protection performance are ≤0.15% by mass percentage. For example, they can be 0.15%, 0.14%, 0.13%, 0.12%, 0.11%, or 0.1%, etc., but are not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0051] Specifically, the aluminum alloy that enhances pedestrian protection performance comprises, by weight percentage:

[0052] Si 0.5-0.6%, Mn 0.08-0.1%, Mg 0.5-0.6%, Fe≤0.1%, Cu≤0.1%, Cr≤0.04%, Zn≤0.1%, Ti≤0.1%, impurity elements≤0.15%, balance Al.

[0053] Furthermore, the present invention provides a method for preparing the aforementioned aluminum alloy with improved pedestrian protection performance, the method comprising:

[0054] According to the formula, after batching, an aluminum alloy ingot with improved pedestrian protection performance is obtained by semi-continuous casting process. Then, it is subjected to hot rolling, annealing, cold rolling, solution treatment, aging treatment and room temperature standing in sequence to obtain an aluminum alloy with improved pedestrian protection performance.

[0055] For example, the process of obtaining aluminum alloy ingots with improved pedestrian protection performance using a semi-continuous casting process can be as follows: aluminum alloy raw materials are batched, then smelted in a furnace to obtain a raw material solution; intermediate alloy additives are added, followed by in-furnace refining and online degassing, and then casting after cooling to obtain aluminum alloy ingots.

[0056] Furthermore, aluminum alloy ingots that meet the aforementioned requirements of this invention can also be prepared using other aluminum alloy preparation processes in the field.

[0057] The melting temperature is 700-730℃, for example, it can be 700℃, 705℃, 710℃, 715℃, 720℃, 725℃ or 730℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0058] The refining temperature inside the furnace is 710-725℃, for example, it can be 710℃, 712℃, 714℃, 716℃, 718℃, 720℃, 722℃, 724℃ or 725℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0059] Specifically, the hot rolling process involves holding the aluminum alloy ingot at 435-475℃ for 3-7 hours, for example, at 435℃, 440℃, 445℃, 450℃, 455℃, 460℃, 465℃, 470℃, or 475℃, and for example, for 3 hours, 4 hours, 5 hours, 6 hours, or 7 hours, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0060] Specifically, the thickness of the hot-rolled sheet is 3-5mm, for example, it can be 3mm, 3.5mm, 4mm, 4.5mm or 5mm, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0061] Specifically, the annealing temperature is 460-490℃, for example, it can be 460℃, 470℃, 480℃ or 490℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0062] Specifically, the annealing holding time is 1.5-5 hours, for example, it can be 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0063] In this invention, the sheet obtained after annealing is cold rolled after being cooled in the furnace.

[0064] Specifically, the thickness of the cold-rolled sheet is 0.7-1.3mm, for example, it can be 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm or 1.3mm, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0065] Specifically, the solution treatment temperature Tc is 470-550℃, for example, it can be 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃ or 550℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0066] Specifically, the solution treatment time t is 3-13 min, for example, it can be 3 min, 4 min, 6 min, 8 min, 10 min, 12 min or 13 min, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0067] Specifically, the temperature and time of the solution treatment satisfy: t = 0.0013 × Tc 2 -1.4305×Tc+400.29.

[0068] In this invention, when performing calculations based on the formula, units are not substituted; only numbers are substituted. The value obtained for t is the number of minutes, and Tc is the corresponding temperature value.

[0069] Specifically, the aging treatment temperature is 150-175℃, for example, it can be 150℃, 155℃, 160℃, 165℃, 170℃ or 175℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0070] Specifically, the time for the time-sensitive processing is 1-6 minutes, for example, it can be 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes or 6 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0071] Specifically, the room temperature for standing is ≤40℃, for example, it can be 40℃, 30℃, 20℃, 10℃ or 5℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0072] Specifically, the time for standing at room temperature is ≥72h, for example, it can be 72h, 74h, 76h, 78h, 80h, 85h, 90h or 95h, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0073] To further illustrate the aluminum alloy that enhances pedestrian protection performance provided by the present invention, specific embodiments are provided as follows:

[0074] Example 1

[0075] This embodiment provides an aluminum plate for improving pedestrian protection performance in the inner panel of a vehicle body. The composition and weight percentage of the aluminum alloy are as follows: Si 0.55%, Mn 0.10%, Mg 0.55%, Fe 0.04%, Cu 0.07%, Cr 0.02%, Zn 0.05%, Ti 0.05%, and the remainder is Al.

[0076] The preparation method includes the following steps:

[0077] (1) Melting and casting: The aluminum alloy ingot with improved pedestrian protection performance is obtained by conventional semi-continuous casting process. The specific process steps include: after the aluminum alloy raw materials are batched, they are charged into the furnace and melted at high temperature to obtain raw material solution; after adding intermediate alloy additives, in-furnace refining and online degassing are carried out, and after cooling, the aluminum alloy ingot is cast.

[0078] (2) Hot rolling: The aluminum alloy ingot described in (1) is heated to 455°C, held for 5 hours and then hot rolled to obtain a hot-rolled plate with a thickness of 4.5 mm.

[0079] (3) Annealing: The hot-rolled plate described in (2) is kept at 475°C for 3.5 hours and then cooled to room temperature in the furnace to obtain an annealed hot-rolled plate;

[0080] (4) Cold rolling: The annealed hot-rolled plate described in (3) is cold-rolled to obtain a cold-rolled plate with a thickness of 0.8 mm;

[0081] (5) Solution treatment: The cold-rolled sheet described in (4) is subjected to solution treatment. The solution temperature and solution time are related by the formula t(min) = 0.0013 × Tc. 2 -1.4305×Tc+400.29, determined to be: the solution treatment temperature is 520℃, the time is 8min, and finally the solution is cooled to room temperature by water quenching;

[0082] (6) Aging treatment: The rolled plate after solution treatment in (5) is subjected to aging treatment to form an aged rolled plate; the aging treatment temperature is 165℃ and the time is 8min, and finally it is cooled to room temperature by air;

[0083] (7) Room temperature placement: After the pre-aging treatment of (6) is carried out at room temperature of 15°C for 72 hours, the rolled plate can be used for deformation behaviors such as stamping and bending.

[0084] Example 2

[0085] This embodiment provides an aluminum plate for improving pedestrian protection performance in the inner panel of a vehicle body. The composition and weight percentage of the aluminum alloy are as follows: Si 0.55%, Mn 0.10%, Mg 0.55%, Fe 0.04%, Cu 0.07%, Cr 0.02%, Zn 0.05%, Ti 0.05%, and the remainder is Al.

[0086] The preparation method includes the following steps:

[0087] (1) Melting and casting: The aluminum alloy ingot with improved pedestrian protection performance is obtained by conventional semi-continuous casting process. The specific process steps include: after the aluminum alloy raw materials are batched, they are charged into the furnace and melted at high temperature to obtain raw material solution; after adding intermediate alloy additives, in-furnace refining and online degassing are carried out, and after cooling, the aluminum alloy ingot is cast.

[0088] (2) Hot rolling: The aluminum alloy ingot described in (1) is heated to 455°C, held for 5 hours and then hot rolled to obtain a hot-rolled plate with a thickness of 4.5 mm.

[0089] (3) Annealing: The hot-rolled plate described in (2) is kept at 475°C for 3.5 hours and then cooled to room temperature in the furnace to obtain an annealed hot-rolled plate;

[0090] (4) Cold rolling: The annealed hot-rolled plate described in (3) is cold-rolled to obtain a cold-rolled plate with a thickness of 0.8 mm;

[0091] (5) Solution treatment: The cold-rolled sheet described in (4) is subjected to solution treatment. The solution temperature and solution time are related by the formula t(min) = 0.0013 × Tc. 2 -1.4305×Tc+400.29, determined to be: the solution treatment temperature is 500℃, the time is 10min, and finally the solution is cooled to room temperature by water quenching;

[0092] (6) Aging treatment: The rolled plate after solution treatment in (5) is subjected to aging treatment to form an aged rolled plate; the aging treatment temperature is 165℃ and the time is 8min, and finally it is cooled to room temperature by air;

[0093] (7) Room temperature placement: After the pre-aging treatment of (6) is carried out at room temperature of 35°C for 72 hours, the rolled plate can be used for deformation behaviors such as stamping and bending.

[0094] Example 3

[0095] This embodiment provides an aluminum plate for improving pedestrian protection performance in the inner panel of a vehicle body. The composition and weight percentage of the aluminum alloy are as follows: Si 0.45%, Mn 0.15%, Mg 0.45%, Fe 0.02%, Cu 0.05%, Cr 0.04%, Zn 0.03%, Ti 0.03%, and the remainder is Al.

[0096] The preparation method includes the following steps:

[0097] (1) Melting and casting: The aluminum alloy ingot with improved pedestrian protection performance is obtained by conventional semi-continuous casting process. The specific process steps include: after the aluminum alloy raw materials are batched, they are charged into the furnace and melted at high temperature to obtain raw material solution; after adding intermediate alloy additives, in-furnace refining and online degassing are carried out, and after cooling, the aluminum alloy ingot is cast.

[0098] (2) Hot rolling: The aluminum alloy ingot described in (1) is heated to 435°C, held for 7 hours and then hot rolled to obtain a hot-rolled plate with a thickness of 3mm.

[0099] (3) Annealing: The hot-rolled plate described in (2) is kept at 460°C for 5 hours and then cooled to room temperature in the furnace to obtain an annealed hot-rolled plate;

[0100] (4) Cold rolling: The annealed hot-rolled plate described in (3) is cold-rolled to obtain a cold-rolled plate with a thickness of 1.3 mm;

[0101] (5) Solution treatment: The cold-rolled sheet described in (4) is subjected to solution treatment. The solution temperature and solution time are related by the formula t(min) = 0.0013 × Tc. 2 -1.4305×Tc+400.29, determined to be: the solution treatment temperature is 490℃, the time is 11.5min, and finally the solution is cooled to room temperature by water quenching;

[0102] (6) Aging treatment: The rolled plate after solution treatment in (5) is subjected to aging treatment to form an aged rolled plate; the aging treatment temperature is 150℃ and the time is 6min, and finally it is cooled to room temperature by air;

[0103] (7) Room temperature placement: After the pre-aging treatment of (6) is carried out at room temperature of 30°C for 72 hours, the rolled plate can be used for deformation behaviors such as stamping and bending.

[0104] Example 4

[0105] This embodiment provides an aluminum plate for improving pedestrian protection performance in the inner panel of a vehicle body. The composition and weight percentage of the aluminum alloy are as follows: Si 0.7%, Mn 0.05%, Mg 0.65%, Fe 0.03%, Cu 0.02%, Cr 0.01%, Zn 0.08%, Ti 0.08%, and the remainder is Al.

[0106] The preparation method includes the following steps:

[0107] (1) Melting and casting: The aluminum alloy ingot with improved pedestrian protection performance is obtained by conventional semi-continuous casting process. The specific process steps include: after the aluminum alloy raw materials are batched, they are charged into the furnace and melted at high temperature to obtain raw material solution; after adding intermediate alloy additives, in-furnace refining and online degassing are carried out, and after cooling, the aluminum alloy ingot is cast.

[0108] (2) Hot rolling: The aluminum alloy ingot described in (1) is heated to 475°C, held for 3 hours and then hot rolled to obtain a hot-rolled plate with a thickness of 5mm.

[0109] (3) Annealing: The hot-rolled plate described in (2) is kept at 490°C for 1.5 hours and then cooled to room temperature in the furnace to obtain an annealed hot-rolled plate;

[0110] (4) Cold rolling: The annealed hot-rolled plate described in (3) is cold-rolled to obtain a cold-rolled plate with a thickness of 1 mm;

[0111] (5) Solution treatment: The cold-rolled sheet described in (4) is subjected to solution treatment. The solution temperature and solution time are related by the formula t(min) = 0.0013 × Tc. 2 -1.4305×Tc+400.29, determined to be: the solution treatment temperature is 510℃, the time is 8.9min, and finally the solution is cooled to room temperature by water quenching;

[0112] (6) Aging treatment: The rolled plate after solution treatment in (5) is subjected to aging treatment to form an aged rolled plate; the aging treatment temperature is 175℃ and the time is 1min, and finally it is cooled to room temperature by air;

[0113] (7) Room temperature placement: After the pre-aging treatment of (6) is carried out at room temperature of 25°C for 72 hours, the rolled plate can be used for deformation behaviors such as stamping and bending.

[0114] Comparative Example 1

[0115] This embodiment provides a commonly used 6016 aluminum sheet for car bodies. The composition and weight percentage of the aluminum alloy are as follows: Si: 1.04%, Mn: 0.10%, Mg: 0.60%, Zr: 0.15%, Fe: 0.04%, Cu: 0.07%, Cr: 0.02%, Zn: 0.05%, and the remainder is Al.

[0116] Includes the following steps:

[0117] (1) Melting and casting: The aluminum alloy ingot with improved pedestrian protection performance is obtained by conventional semi-continuous casting process. The specific process steps include: after the aluminum alloy raw materials are batched, they are charged into the furnace and melted at high temperature to obtain raw material solution; after adding intermediate alloy additives, in-furnace refining and online degassing are carried out, and after cooling, the aluminum alloy ingot is cast.

[0118] (2) Hot rolling: The aluminum alloy ingot described in (1) is heated to 455°C, held for 5 hours and then hot rolled to obtain a hot-rolled plate with a thickness of 4.5 mm.

[0119] (3) Annealing: The hot-rolled plate described in (2) is kept at 475°C for 3.5 hours and then cooled to room temperature in the furnace to obtain an annealed hot-rolled plate;

[0120] (4) Cold rolling: The annealed hot-rolled plate described in (3) is cold-rolled to obtain a cold-rolled plate with a thickness of 0.8 mm;

[0121] (5) Solution treatment: The cold-rolled sheet described in (4) is subjected to solution treatment at a temperature of 535°C for 14 minutes, and is finally cooled to room temperature by water quenching.

[0122] (6) Aging treatment: The rolled plate after solution treatment in (5) is subjected to aging treatment to form an aged rolled plate; the aging treatment temperature is 165℃ and the time is 8min, and finally it is cooled to room temperature by air;

[0123] (7) Room temperature placement: After the pre-aging treatment of (6) is carried out at room temperature for 72 hours, the rolled plate can be used for deformation behaviors such as stamping and bending.

[0124] Comparative Example 2

[0125] The only difference from Example 1 is that the silicon content is 1% by mass.

[0126] Comparative Example 3

[0127] The only difference from Example 1 is that the silicon content is 0.3% by mass.

[0128] Comparative Example 4

[0129] The only difference from Example 1 is that the solution treatment time is 20 minutes.

[0130] Comparative Example 5

[0131] The only difference from Example 1 is that the solution treatment temperature is 550°C.

[0132] Comparative Example 6

[0133] The only difference from Example 1 is that the solution treatment time is 3 minutes.

[0134] Mechanical property comparison tests were conducted on the aluminum alloy sheets obtained from each embodiment and comparative example. The room temperature mechanical property test method was in accordance with "GB / T 228.1 Metallic materials - Tensile testing - Part 1: Room temperature test method 1", and the bake hardening performance test method was in accordance with "GB / T 33227 Aluminum and aluminum alloy sheet and strip for automobiles". The specimens were selected according to "GB / T 16865 Deformed aluminum, magnesium alloys and their alloy processed products - Specimens and methods for tensile testing", and the gauge length rectangular P003 type specimens were selected. The results of the room temperature mechanical property test are shown in Table 1, and the results of the bake hardening performance test are shown in Table 2.

[0135] Table 1

[0136] tensile strength Yield strength Elongation after fracture n4～6 R8～12 Example 1 132MPa 66MPa 23.5％ 0.30 0.66 Example 2 134MPa 65MPa 24.0％ 0.29 0.65 Example 3 133MPa 66MPa 24.0％ 0.29 0.64 Example 4 135MPa 67MPa 23.5％ 0.30 0.65 Comparative Example 1 188MPa 91MPa 24.0％ 0.29 0.67 Comparative Example 2 140MPa 75MPa 13.5％ 0.24 0.49 Comparative Example 3 110MPa 55MPa 9.5％ 0.23 0.43 Comparative Example 4 155MPa 83MPa 20.5％ 0.27 0.59 Comparative Example 5 140MPa 79MPa 19.5％ 0.26 0.60 Comparative Example 6 90MPa 55MPa 15.5％ 0.23 0.51

[0137] Table 2

[0138] plan tensile strength Yield strength Elongation after fracture Example 1 175MPa 114MPa 16.5％ Example 2 178MPa 119MPa 16.0％ Example 3 175MPa 113MPa 16.0％ Example 4 177MPa 116MPa 16.5％ Comparative Example 1 240MPa 174MPa 17.0％ Comparative Example 2 183MPa 127MPa 6.5％ Comparative Example 3 135MPa 84MPa 3.5％ Comparative Example 4 195MPa 131MPa 11.5％ Comparative Example 5 179MPa 118MPa 12.0％ Comparative Example 6 110MPa 68MPa 9.5％

[0139] As can be seen from Tables 1 and 2, compared with the comparative example, the embodiment obtained by adjusting the solution temperature and solution time parameters scientifically and quantitatively has a significantly lower yield strength, while the plasticity-related indicators, such as elongation after fracture, n value and r value, remain at a comparable level and do not decrease.

[0140] The aluminum alloy sheets obtained in Example 1 and Comparative Example 1 were used to manufacture the inner panels of the front hood assembly for a certain vehicle model. The inner panels had identical structures and were ultimately assembled with other parts into the front hood assembly. Pedestrian head protection tests were then conducted on each panel. The test method was simplified according to the latest Euro NCAP requirements. The injury values ​​at 48 points were statistically analyzed and colored to form injury distribution maps, as shown below. Figure 1 and Figure 2 As shown in the figure, 1 is red, 2 is yellow, and 3 is green. Each red area scores 0 points, each yellow area scores 1 point, and each green area scores 2 points. The final statistical analysis results are shown in Table 3.

[0141] Depend on Figure 1 and Figure 2 The comparison shows that by using aluminum plates with improved pedestrian protection performance in the inner body panels, the distribution of head injury values ​​for pedestrian protection is significantly improved due to their lower yield strength.

[0142] Table 3

[0143]

[0144] As can be quantitatively seen from Table 3, the damage score of the parts made of aluminum plates with improved pedestrian protection performance in the vehicle body inner panel is 63 points, which is 31.25% higher than the damage reduction effect of ordinary aluminum plate solutions.

[0145] The present invention is described above through the embodiments to illustrate its detailed structural features, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0146] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0147] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0148] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. An aluminum alloy for improving pedestrian protection performance, characterized in that, The aluminum alloy used to enhance pedestrian protection performance comprises, by weight percentage: Si 0.45-0.7%, Mn 0.05-0.15%, Mg 0.45-0.65%, Fe≤0.1%, Cu≤0.1%, Cr≤0.04%, Zn≤0.1%, Ti≤0.1%, impurity elements≤0.15%, balance Al; The performance indicators of the aluminum alloy are: R p0.2 For 65-67 MPa, R m For 132-135 MPa, A 80mm ≥23.5%, n 4~6 ≥0.29, r 8~12 ≥0.64; The performance index after paint baking treatment is: R p0.2 For 113-119 MPa, R m For 175-178 MPa, A 80mm ≥16%; The solution treatment temperature and time in the preparation of the aluminum alloy for improving pedestrian protection performance satisfy: t = 0.0013 × Tc 2 -1.4305×Tc+400.29; the solution treatment temperature Tc is 470-550℃; the solution treatment time t is 3-13min.

2. The aluminum alloy for improving pedestrian protection performance as described in claim 1, characterized in that, The aluminum alloy used to enhance pedestrian protection performance comprises, by weight percentage: Si 0.5-0.6%, Mn 0.08-0.1%, Mg 0.5-0.6%, Fe≤0.1%, Cu≤0.1%, Cr≤0.04%, Zn≤0.1%, Ti≤0.1%, impurity elements≤0.15%, balance Al.

3. A method for preparing an aluminum alloy with improved pedestrian protection performance as described in claim 1 or 2, characterized in that, The preparation method includes: According to the formula, after batching, an aluminum alloy ingot with improved pedestrian protection performance is obtained by semi-continuous casting process. Then, it is subjected to hot rolling, annealing, cold rolling, solution treatment, aging treatment and room temperature standing in sequence to obtain an aluminum alloy with improved pedestrian protection performance.

4. The preparation method according to claim 3, characterized in that, The hot rolling process begins after the aluminum alloy ingot is held at 435-475℃ for 3-7 hours.

5. The preparation method according to claim 3, characterized in that, The thickness of the hot-rolled sheet is 3-5 mm.

6. The preparation method according to claim 3, characterized in that, The annealing temperature is 460-490℃.

7. The preparation method according to claim 3, characterized in that, The annealing holding time is 1.5-5 hours.

8. The preparation method according to claim 3, characterized in that, The annealed sheet material is then cold-rolled after being cooled in the furnace.

9. The preparation method according to claim 3, characterized in that, The thickness of the cold-rolled sheet is 0.7-1.3 mm.

10. The preparation method according to claim 3, characterized in that, The temperature and time of the solution treatment satisfy: t = 0.0013 × Tc 2 -1.4305×Tc+400.

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11. The preparation method according to claim 3, characterized in that, The aging treatment temperature is 150-175℃.

12. The preparation method according to claim 3, characterized in that, The time for the time-sensitive processing is 1-6 minutes.

13. The preparation method according to claim 3, characterized in that, The room temperature for resting is ≤40℃.

14. The preparation method according to claim 3, characterized in that, The time for standing at room temperature is ≥72 hours.

15. The use of an aluminum alloy as described in claim 1 or 2 to improve pedestrian protection performance, characterized in that, The applications include using the aluminum alloy described above, which enhances pedestrian protection, to manufacture the inner panel of a car hood.

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