High-strength large-differential-thickness aluminum alloy differential thickness plate and preparation method and application thereof

Abstract

The application discloses a high-strength large-difference-thickness-ratio aluminum alloy differential thickness plate and a preparation method and application thereof, and belongs to the technical field of rolling. The preparation method comprises the following steps: T6 state aluminum alloy equal-thickness plate with a thickness of 2.5 mm is subjected to first-pass variable-thickness rolling on a cold rolling mill, the roll gap is dynamically adjusted in real time, and aluminum alloy differential thickness plate with a thickness of 1.1 mm in a thin area and a thickness of 2.4 mm in a thick area is obtained; solid solution treatment and pre-aging treatment are carried out; the aluminum alloy differential thickness plate after the pre-aging treatment is subjected to second-pass variable-thickness rolling, the roll gap is dynamically adjusted in real time, and aluminum alloy differential thickness plate with a thin area thickness of 1.0 mm and a thick area thickness of 2.3 mm is obtained; and in sequence, post-aging treatment, pre-tensile strain treatment and simulated baking paint hardening treatment are carried out. The tensile strength is 370 MPa-410 MPa, the elongation after fracture is 14%-21%, the strength is high, the plasticity is excellent, the large-difference-thickness ratio is high, and the structure self weight of automobile parts can be significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of rolling technology, specifically relating to a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio, its preparation method, and its application. Background Technology

[0002] Cold-rolled differential thickness plates have been widely used in the automotive, shipbuilding, and bridge industries, with core advantages including material savings, weight reduction, fewer welds, cost control, and increased production efficiency. These plates have a clearly defined structure, including thin and thick sections, and a transition zone connecting them. Compared to laser-welded plates, cold-rolled differential thickness plates, due to their weld-free structure, offer superior product quality, lower production costs, and higher efficiency. More importantly, the length, slope, and other shape parameters of the transition zone can be customized based on the stress distribution during the actual service life of the stamped parts, achieving "on-demand" material thickness allocation. This maximizes material efficiency and makes them a preferred material for automotive lightweighting due to their superior material-saving and weight-reduction effects, gradually becoming a focus of industry attention. Currently, differential thickness plate technology has been successfully applied to the production of lightweight automotive components both domestically and internationally, capable of processing various key components such as B-pillars, anti-collision beams, and front longitudinal beams. Low-alloy steel differential thickness plates and hot-formed differential thickness plates are the most commonly used, but their thickness ratio is generally less than or equal to 1:2.

[0003] With the rapid development of the new energy vehicle industry, driving range and energy efficiency have become the core competitive focus, and lightweight vehicle body is one of the key paths to solving this problem. As a typical lightweight material, aluminum alloy possesses excellent properties such as high strength, corrosion resistance, and ease of forming. Applying it to the body and chassis components of new energy vehicles can effectively reduce vehicle weight, thereby reducing the load on the powertrain and achieving the dual goals of reducing energy consumption and improving power performance. In recent years, the application rate of aluminum alloy in automotive body and chassis components has been continuously increasing, and compared with traditional steel body bodies, the weight reduction effect of aluminum alloy bodies is more prominent.

[0004] The organic integration of variable thickness rolling technology with aluminum alloy materials to develop high-strength aluminum alloy differential thickness plates is expected to further promote the iterative upgrade of automotive lightweighting technology. From an application prospect perspective, compared to traditional constant thickness aluminum alloy parts, aluminum alloy differential thickness plate parts can achieve a weight reduction of 20%-30%, and the material utilization rate can be increased to over 60%. Its applicable scenarios cover core areas such as automotive chassis components, crossbeams, door components, seat components, and body structural parts. Currently, aluminum alloy differential thickness plates have not yet achieved industrial-scale mass production, especially the research on the preparation process of high-strength aluminum alloy differential thickness plates with a thickness ratio greater than 1:2 is still in the exploratory stage, lacking systematic and in-depth technical accumulation. Against this backdrop, conducting research and development and application of high-strength aluminum alloy differential thickness plates with a large thickness ratio for automotive applications is a new energy-saving and material-saving technology direction with both technical characteristics and application value. Breakthroughs in this technology can not only provide a better lightweighting solution for the new energy vehicle industry, but also have extremely high practical application value and broad market prospects. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a high-strength aluminum alloy differential thickness plate with a large thickness difference ratio and its preparation method. Through double-pass variable thickness rolling, solution treatment, pre-aging, re-aging, pre-tensile strain and simulated baking paint hardening treatment, a high-strength aluminum alloy differential thickness plate with a large thickness difference ratio and excellent plasticity is obtained.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio, comprising the following steps:

[0008] First pass of variable thickness rolling:

[0009] A 2.5mm thick T6 aluminum alloy sheet of equal thickness is rolled in the first pass of a cold rolling mill with variable thickness. The roll gap is dynamically adjusted in real time to roll the aluminum alloy sheet of equal thickness into an aluminum alloy sheet of differential thickness. The thicknesses of the thin and thick regions are 1.1mm and 2.4mm, respectively, and the transition curve is a linear dominant transition.

[0010] Solution treatment:

[0011] The aluminum alloy differential thickness plate obtained from the first pass of variable thickness rolling is subjected to solution treatment.

[0012] Pre-aging treatment:

[0013] Pre-aging treatment is performed on aluminum alloy differential thickness plates after solution treatment;

[0014] Second pass variable thickness rolling:

[0015] The aluminum alloy differential thickness plate after pre-aging treatment is subjected to a second pass of variable thickness rolling on a cold rolling mill. The roll gap is dynamically adjusted in real time to obtain the aluminum alloy differential thickness plate after the second pass of variable thickness rolling. The thickness of the thin zone and the thick zone are 1.0 mm and 2.3 mm, respectively, with a thickness difference ratio of 1:2.3. The transition zone curve is a linear dominant transition.

[0016] Re-approval:

[0017] The aluminum alloy differential thickness plate after the second rolling process is subjected to re-aging treatment.

[0018] Pre-stretch strain treatment:

[0019] The aluminum alloy differential thickness plate after reaging was subjected to pre-tensile strain simulation stamping.

[0020] Simulated paint curing process:

[0021] Aluminum alloy differential thickness plates with pre-stretch strain are subjected to simulated baking paint hardening treatment to obtain high-strength aluminum alloy differential thickness plates with large thickness ratio.

[0022] Furthermore, in the first pass of variable thickness rolling, the aluminum alloy constant thickness plate, by mass percentage, comprises the following components: Mg: 1.12%-1.15%, Si: 0.70%-0.75%, Mn: 0.10%-0.12%, Cu: 0.19%-0.21%, Ti: 0.03%-0.04%, Zn: 0.09%-0.10%, Cr: 0.08%-0.09%, Fe: 0.50%-0.55%, with the balance being Al.

[0023] Furthermore, in the solution treatment, the solution temperature is 540℃-550℃, and the solution time is 10min-30min.

[0024] Furthermore, in the pre-aging treatment, the pre-aging temperature is 120℃-130℃, and the pre-aging time is 1h-3h.

[0025] Furthermore, in the re-aging treatment, the re-aging temperature is 120℃-130℃, and the re-aging time is 1h-5h.

[0026] Furthermore, in the pre-stretch strain treatment, the pre-stretch strain is 2%-3%.

[0027] Furthermore, in the simulated paint curing process, the paint curing temperature is 170℃-180℃, and the heating and holding time is 25min-35min.

[0028] Secondly, the present invention provides a high-strength aluminum alloy differential thickness plate with a large thickness ratio, which is prepared by the above-mentioned preparation method of the high-strength aluminum alloy differential thickness plate with a large thickness ratio.

[0029] Furthermore, the thickness of the thick section of the high-strength aluminum alloy plate with a large thickness difference is 2.3 mm, the thickness of the thin section is 1.0 mm, the thickness difference ratio is 1:2.3, and it has a transition zone with a straight-line dominant transition curve; the tensile strength is 370 MPa-410 MPa, and the elongation after fracture is 14%-21%.

[0030] Thirdly, the present invention provides an application of high-strength aluminum alloy differential thickness plate with large differential thickness ratio in automobile manufacturing.

[0031] Advantages and effects of the present invention:

[0032] This invention aims to develop a high-strength aluminum alloy differential thickness plate suitable for automobile manufacturing. This plate exhibits a tensile strength of 370MPa-410MPa and an elongation after fracture of 14%-21%. The prepared differential thickness plate possesses outstanding characteristics of high strength, excellent plasticity, and a large differential thickness ratio, making it a core raw material for lightweight automotive components. It can significantly reduce the structural weight of automotive parts, contributing to energy conservation and emission reduction goals. This invention employs a double-pass variable thickness rolling combined with heat treatment process to prepare the aluminum alloy differential thickness plate, offering advantages such as high production efficiency and low cost, facilitating large-scale industrial mass production. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the variable thickness rolling process for the high-strength aluminum alloy differential thickness plate with a large differential thickness ratio according to the present invention.

[0034] Figure 2 This is a schematic diagram of the variable thickness of the high-strength aluminum alloy differential thickness plate of the present invention with a large differential thickness ratio;

[0035] Figure 3 The stress-strain curve of the high-strength aluminum alloy differential thickness plate with large differential thickness ratio prepared in Example 1 is shown. Detailed Implementation

[0036] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0037] A method for preparing a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio includes the following steps:

[0038] First pass of variable thickness rolling:

[0039] according to Figure 1The rolling schematic diagram shows that a 2.5mm thick T6 state aluminum alloy sheet of uniform thickness is rolled in the first pass of a cold rolling mill with variable thickness. The roll gap is dynamically adjusted in real time to roll the aluminum alloy sheet of uniform thickness into an aluminum alloy sheet of differential thickness. The thicknesses of the thin and thick regions are 1.1mm and 2.4mm, respectively, and the transition curve is a linear dominant transition. The aluminum alloy sheet of uniform thickness includes the following components: Mg: 1.12%-1.15%, Si: 0.70%-0.75%, Mn: 0.10%-0.12%, Cu: 0.19%-0.21%, Ti: 0.03%-0.04%, Zn: 0.09%-0.10%, Cr: 0.08%-0.09%, Fe: 0.50%-0.55%, with the balance being Al.

[0040] Solution treatment:

[0041] The aluminum alloy differential thickness plate obtained by the first pass of variable thickness rolling is solution treated at 540℃-550℃ for 10min-30min.

[0042] Pre-aging treatment:

[0043] The aluminum alloy differential thickness plate after solution treatment is pre-aged at 120℃-130℃ for 1h-3h;

[0044] Second pass variable thickness rolling:

[0045] according to Figure 1 The rolling schematic diagram shows that the pre-aged aluminum alloy differential thickness plate is subjected to a second pass of variable thickness rolling on a cold rolling mill. The roll gap is dynamically adjusted in real time to obtain the aluminum alloy differential thickness plate after the second pass of variable thickness rolling. The thickness of the thin zone and the thick zone are 1.0 mm and 2.3 mm, respectively, with a thickness difference ratio of 1:2.3. The transition zone curve is a linear dominant transition.

[0046] Re-approval:

[0047] The aluminum alloy differential thickness plate after the second rolling is subjected to aging treatment at 120℃-130℃ for 1h-5h.

[0048] Pre-stretch strain treatment:

[0049] The aluminum alloy differential thickness plate after reaging was subjected to pre-stretch strain simulation stamping, with a pre-stretch strain of 2%-3%;

[0050] Simulated paint curing process:

[0051] The pre-stretched aluminum alloy differential thickness plate is heated at 170℃-180℃ for 25min-35min to undergo simulated paint hardening treatment, resulting in a high-strength aluminum alloy differential thickness plate with a large thickness ratio.

[0052] The high-strength, high-aspect-ratio aluminum alloy differential thickness plate prepared by the above method, such as... Figure 2 As shown, the thickness of its thick section is 2.3 mm, the thickness of its thin section is 1.0 mm, the thickness difference ratio is 1:2.3, and it has a transition zone. The transition zone curve is a straight-line dominant transition. Its tensile strength is 370 MPa-410 MPa, and its elongation after fracture is 14%-21%.

[0053] The application of a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio in automobile manufacturing covers core areas such as automobile chassis components, crossbeams, door components, seat components, and body structural parts.

[0054] Example 1

[0055] A method for preparing a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio includes the following steps:

[0056] First pass of variable thickness rolling:

[0057] A 2.5mm thick T6 state aluminum alloy sheet of uniform thickness is subjected to a first pass of variable thickness rolling on a cold rolling mill. The roll gap is dynamically adjusted in real time to roll the aluminum alloy sheet of uniform thickness into an aluminum alloy sheet of differential thickness. The thicknesses of the thin and thick regions are 1.1mm and 2.4mm, respectively, and the transition curve is a linear dominant transition. The T6 state aluminum alloy sheet of uniform thickness comprises the following components by mass percentage: Mg: 1.13%, Si: 0.73%, Mn: 0.104%, Cu: 0.196%, Ti: 0.037%, Zn: 0.091%, Cr: 0.087%, Fe: 0.51%, with the balance being Al.

[0058] Solution treatment:

[0059] The aluminum alloy differential thickness plate obtained by the first pass of variable thickness rolling was solution treated at 550℃ for 10 min.

[0060] Pre-aging treatment:

[0061] The aluminum alloy differential thickness plate after solution treatment was pre-aged at 120℃ for 1 hour.

[0062] Second pass variable thickness rolling:

[0063] The aluminum alloy differential thickness plate after pre-aging treatment is subjected to a second pass of variable thickness rolling on a cold rolling mill. The roll gap is dynamically adjusted in real time to obtain the aluminum alloy differential thickness plate after the second pass of variable thickness rolling. The thickness of the thin zone and the thick zone are 1.0 mm and 2.3 mm, respectively, with a thickness difference ratio of 1:2.3. The transition zone curve is a linear dominant transition.

[0064] Re-approval:

[0065] The aluminum alloy differential thickness plate after the second rolling is subjected to aging treatment at 120℃ for 3 hours.

[0066] Pre-stretch strain treatment:

[0067] The aluminum alloy differential thickness plate after re-aging was subjected to pre-stretch strain simulation stamping, with a pre-stretch strain of 2%.

[0068] Simulated paint curing process:

[0069] The pre-stretched aluminum alloy differential thickness plate was heated at 180℃ and held for 30 minutes to undergo simulated paint hardening treatment, resulting in a high-strength aluminum alloy differential thickness plate with a large thickness ratio.

[0070] In Example 1, the high-strength aluminum alloy plate with a large thickness difference has a thickness of 2.3 mm in the thick section and 1.0 mm in the thin section, resulting in a thickness difference ratio of 1:2.3. It also includes a transition zone with a linear-dominant transition curve. Mechanical property testing was performed, such as... Figure 3 As shown, the tensile strengths of the thin and thick regions are 400 MPa and 370 MPa, respectively, and the elongation after fracture is 14% and 21%, respectively.

[0071] Example 2

[0072] A method for preparing a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio includes the following steps:

[0073] First pass of variable thickness rolling:

[0074] A 2.5mm thick T6 state aluminum alloy sheet of uniform thickness is subjected to a first pass of variable thickness rolling on a cold rolling mill. The roll gap is dynamically adjusted in real time to roll the aluminum alloy sheet of uniform thickness into an aluminum alloy sheet of differential thickness. The thicknesses of the thin and thick regions are 1.1mm and 2.4mm, respectively, and the transition curve is a linear dominant transition. The T6 state aluminum alloy sheet of uniform thickness comprises the following components by mass percentage: Mg: 1.12%, Si: 0.75%, Mn: 0.10%, Cu: 0.19%, Ti: 0.03%, Zn: 0.10%, Cr: 0.09%, Fe: 0.55%, with the balance being Al.

[0075] Solution treatment:

[0076] The aluminum alloy differential thickness plate obtained by the first pass of variable thickness rolling was solution treated at 545℃ for 20 minutes.

[0077] Pre-aging treatment:

[0078] The aluminum alloy differential thickness plate after solution treatment was pre-aged at 125℃ for 2 hours.

[0079] Second pass variable thickness rolling:

[0080] The aluminum alloy differential thickness plate after pre-aging treatment is subjected to a second pass of variable thickness rolling on a cold rolling mill. The roll gap is dynamically adjusted in real time to obtain the aluminum alloy differential thickness plate after the second pass of variable thickness rolling. The thickness of the thin zone and the thick zone are 1.0 mm and 2.3 mm, respectively, with a thickness difference ratio of 1:2.3. The transition zone curve is a linear dominant transition.

[0081] Re-approval:

[0082] The aluminum alloy differential thickness plate after the second rolling is subjected to aging treatment at 125℃ for 5 hours.

[0083] Pre-stretch strain treatment:

[0084] The aluminum alloy differential thickness plate after re-aging was subjected to pre-stretch strain simulation stamping, with a pre-stretch strain of 3%.

[0085] Simulated paint curing process:

[0086] The pre-stretched aluminum alloy differential thickness plate was heated at 170℃ and held for 35 minutes to undergo simulated paint hardening treatment, resulting in a high-strength aluminum alloy differential thickness plate with a large thickness ratio.

[0087] The high-strength aluminum alloy plate with a large thickness difference ratio prepared in Example 2 has a thickness of 2.3 mm in the thick section and 1.0 mm in the thin section, with a thickness difference ratio of 1:2.3, and includes a transition zone. The transition zone curve is a linear-dominant type. Mechanical property testing was conducted, and the tensile strengths of the thin and thick sections were measured to be 410 MPa and 380 MPa, respectively, with elongation after fracture of 14% and 20%, respectively.

[0088] Example 3

[0089] A method for preparing a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio includes the following steps:

[0090] First pass of variable thickness rolling:

[0091] A 2.5mm thick T6 state aluminum alloy sheet of uniform thickness is subjected to a first pass of variable thickness rolling on a cold rolling mill. The roll gap is dynamically adjusted in real time to roll the aluminum alloy sheet of uniform thickness into an aluminum alloy sheet of differential thickness. The thicknesses of the thin and thick regions are 1.1mm and 2.4mm, respectively, and the transition curve is a linear dominant transition. The T6 state aluminum alloy sheet of uniform thickness comprises the following components by mass percentage: Mg: 1.15%, Si: 0.70%, Mn: 0.12%, Cu: 0.21%, Ti: 0.04%, Zn: 0.09%, Cr: 0.08%, Fe: 0.50%, with the balance being Al.

[0092] Solution treatment:

[0093] The aluminum alloy differential thickness plate obtained by the first pass of variable thickness rolling was solution treated at 540℃ for 30 minutes.

[0094] Pre-aging treatment:

[0095] The aluminum alloy differential thickness plate after solution treatment was pre-aged at 130℃ for 3 hours.

[0096] Second pass variable thickness rolling:

[0097] The aluminum alloy differential thickness plate after pre-aging treatment is subjected to a second pass of variable thickness rolling on a cold rolling mill. The roll gap is dynamically adjusted in real time to obtain the aluminum alloy differential thickness plate after the second pass of variable thickness rolling. The thickness of the thin zone and the thick zone are 1.0 mm and 2.3 mm, respectively, with a thickness difference ratio of 1:2.3. The transition zone curve is a linear dominant transition.

[0098] Re-approval:

[0099] The aluminum alloy differential thickness plate after the second rolling is subjected to aging treatment at 130℃ for 1 hour.

[0100] Pre-stretch strain treatment:

[0101] The aluminum alloy differential thickness plate after re-aging was subjected to pre-stretch strain simulation stamping, with a pre-stretch strain of 2%.

[0102] Simulated paint curing process:

[0103] The pre-stretched aluminum alloy differential thickness plate was heated at 175℃ for 25 minutes and subjected to simulated paint hardening treatment to obtain a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio.

[0104] The high-strength aluminum alloy plate with a large thickness difference ratio prepared in Example 3 has a thickness of 2.3 mm in the thick section and 1.0 mm in the thin section, with a thickness difference ratio of 1:2.3, and includes a transition zone. The transition zone curve is a linear-dominant type. Mechanical property testing was conducted, and the tensile strengths of the thin and thick sections were measured to be 403 MPa and 378 MPa, respectively, with elongation after fracture of 15% and 21%, respectively.

Claims

1. A method for preparing a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio, characterized in that, Includes the following steps: First pass of variable thickness rolling: A 2.5mm thick T6 state aluminum alloy sheet of uniform thickness is subjected to a first pass of variable thickness rolling on a cold rolling mill. The roll gap is dynamically adjusted in real time to roll the aluminum alloy sheet of uniform thickness into an aluminum alloy sheet of differential thickness. The thicknesses of the thin and thick regions are 1.1mm and 2.4mm, respectively, and the transition curve is a linear dominant transition. The aluminum alloy sheet of uniform thickness comprises the following components by mass percentage: Mg: 1.12%-1.15%, Si: 0.70%-0.75%, Mn: 0.10%-0.12%, Cu: 0.19%-0.21%, Ti: 0.03%-0.04%, Zn: 0.09%-0.10%, Cr: 0.08%-0.09%, Fe: 0.50%-0.55%, with the balance being Al. Solution treatment: The aluminum alloy differential thickness plate obtained from the first pass of variable thickness rolling is subjected to solution treatment. Pre-aging treatment: The aluminum alloy differential thickness plate after solution treatment is subjected to a pre-aging treatment of 1h-3h; Second pass variable thickness rolling: The aluminum alloy differential thickness plate after pre-aging treatment is subjected to a second pass of variable thickness rolling on a cold rolling mill. The roll gap is dynamically adjusted in real time to obtain the aluminum alloy differential thickness plate after the second pass of variable thickness rolling. The thickness of the thin zone and the thick zone are 1.0 mm and 2.3 mm, respectively, with a thickness difference ratio of 1:2.

3. The transition zone curve is a linear dominant transition. Re-approval: The aluminum alloy differential thickness plate after the second rolling is subjected to a re-aging treatment of 1h-5h. Pre-stretch strain treatment: The re-aged aluminum alloy differential thickness plate was subjected to pre-tensile strain simulation stamping; the pre-tensile strain was 2%-3%; Simulated paint curing process: Aluminum alloy differential thickness plates with pre-stretch strain are subjected to simulated baking paint hardening treatment to obtain high-strength aluminum alloy differential thickness plates with large thickness ratio.

2. The method for preparing a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio as described in claim 1, characterized in that, During the solution treatment, the solution temperature is 540℃-550℃ and the solution time is 10min-30min.

3. The method for preparing a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio as described in claim 1, characterized in that, During the pre-aging treatment, the pre-aging temperature is 120℃-130℃.

4. The method for preparing a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio as described in claim 1, characterized in that, During the re-aging process, the re-aging temperature is 120℃-130℃.

5. The method for preparing a high-strength aluminum alloy differential thickness plate with a large differential thickness ratio as described in claim 1, characterized in that, In the simulated paint curing process, the paint curing temperature is 170℃-180℃, and the heating and holding time is 25min-35min.

6. A high-strength aluminum alloy plate with a large thickness difference ratio, characterized in that, The high-strength aluminum alloy differential thickness plate with a large differential thickness ratio is prepared by the preparation method of any one of claims 1-5.

7. A high-strength aluminum alloy plate with a large thickness difference ratio as described in claim 6, characterized in that, The thickness of the thick section of the high-strength aluminum alloy plate with a large thickness difference is 2.3 mm, the thickness of the thin section is 1.0 mm, the thickness difference ratio is 1:2.3, and it has a transition zone with a straight-line dominant transition curve; the tensile strength is 370MPa-410MPa, and the elongation after fracture is 14%-21%.

8. The application of the high-strength, high-thickness-ratio aluminum alloy differential plate as described in claim 6 in automobile manufacturing.

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