A high-strength and corrosion-resistant Al-Mg-Mn alloy plate and a short-process processing method thereof

Abstract

This invention belongs to the field of aluminum alloy sheet design and processing, specifically relating to a high-strength, corrosion-resistant Al-Mg-Mn alloy sheet and its short-process processing method. The short-process processing method for this high-strength, corrosion-resistant Al-Mg-Mn alloy sheet combines short-process processing with micro-alloying, and employs continuous casting and rolling combined with two annealing processes. This shortens the processing flow, saves energy and costs, and comprehensively improves the mechanical strength, plasticity, and corrosion resistance of the short-processed Al-Mg-Mn alloy sheet through the synergistic effect of micro-alloying, three-pass continuous cooling rolling, and two annealing processes. The resulting alloy sheet is highly suitable for high-performance special vehicle and marine structural components.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy sheet design and processing, specifically relating to a high-strength and corrosion-resistant Al-Mg-Mn alloy sheet and its short-process processing method. Background Technology

[0002] High-Mg-content 5xxx series aluminum alloys are widely used in the shipbuilding and automotive industries due to their advantages such as low density, high specific strength, and good corrosion resistance. However, with the continuous development of lightweight technology, high-end equipment is placing increasingly stringent requirements on the performance of 5xxx series alloys. At the same time, energy conservation, emission reduction, and green manufacturing have become the development themes of the new era and represent the future development direction of aluminum and aluminum alloys.

[0003] In the aluminum processing industry, short-process processing of aluminum alloy sheets, such as continuous casting and rolling, directly casts molten aluminum into slabs, and then uses residual heat to roll them into sheets. Compared with the traditional casting and rolling process, it eliminates processes such as preheating and edge trimming, significantly saving energy and costs, and is one of the future development directions of aluminum processing. However, in the existing technology, short-process processing of aluminum alloy sheets still has problems such as compositional segregation and low strength and plasticity. This contradiction between high performance and short process has been restricting the large-scale application of short-process processing technology for aluminum alloy sheets.

[0004] Therefore, there is an urgent need to develop a high-strength, corrosion-resistant Al-Mg-Mn alloy and its corresponding short-process processing method that can meet the service requirements of high-end equipment. Summary of the Invention

[0005] The purpose of this invention is to provide a short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates. This method combines short-process processing with micro-alloying, which not only eliminates processes such as rolling, heating, preheating, and edge trimming and milling, thus shortening the processing time and saving energy and costs, but also effectively improves the elongation and corrosion resistance of the aluminum alloy plates while increasing their strength. This solves the problem that short-process processing of Al-Mg-Mn alloy plates results in insufficient strength, toughness, and corrosion resistance, thus hindering their large-scale application.

[0006] Another objective of this invention is to provide a high-strength, corrosion-resistant Al-Mg-Mn alloy sheet, which features high strength, high toughness, and high corrosion resistance, making it suitable for the application requirements of aluminum alloy materials in high-end equipment.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] A short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates includes the following steps:

[0009] (1) Microalloying elements are added to the Al-Mg-Mn basic alloy, and microalloying melting is carried out at 720-750℃, and then casting is performed to obtain a billet; the microalloying elements are selected from two or three of Zr, Sc and Er.

[0010] (2) Cool the billet obtained in step (1) to 400-410℃, and then use the residual heat to perform three consecutive cooling rolling deformation treatment on the billet to obtain a three-rolled plate. Then, anneal the three-rolled plate at 390-410℃ and then cool it. In the three consecutive cooling rolling deformation treatment, the temperature of the first rolling is 400-410℃, the temperature of the second rolling is 280-290℃, and the temperature of the third rolling is 70-85℃.

[0011] (3) The plate after cooling in step (2) is subjected to multiple cold rolling processes, and then subjected to secondary annealing at 170-180℃, followed by cooling, to obtain the high-strength corrosion-resistant Al-Mg-Mn alloy plate.

[0012] The present invention provides a short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates. By introducing microalloying elements (two or three of Zr, Sc, and Er) into the Al-Mg-Mn base alloy for microalloying treatment, the microstructure of the Al-Mg-Mn alloy plates can be refined and homogenized in a short process. In particular, it helps to effectively precipitate nanophases through subsequent secondary annealing processes, thereby improving the strength and toughness of the plates.

[0013] Furthermore, this invention directly utilizes the residual heat of the cast billet for three-pass continuous cooling rolling deformation treatment. Compared with conventional processes, on the one hand, it eliminates the preheating process of cooling and then heating the cast billet before rolling, shortening the plate preparation process and saving energy and costs. On the other hand, the use of three-pass continuous cooling rolling can ensure the inheritance of the microalloying effect while meeting the actual production requirements of continuous casting and rolling, thereby achieving the goal of improving the strength, toughness and corrosion resistance of the final Al-Mg-Mn alloy plate in a short process.

[0014] Subsequently, the present invention employs a single annealing process after three consecutive rolling mills, which effectively promotes the precipitation of nano-reinforcing phases, significantly improving the strength of the Al-Mg-Mn alloy sheet while ensuring its elongation and improving its corrosion resistance. Furthermore, the present invention increases the deformation degree of the alloy sheet through cold rolling, further refining the sheet microstructure and increasing the driving force for nano-precipitation. Even further, a second annealing treatment after cold rolling effectively improves the elongation while maintaining the sheet's high strength.

[0015] Therefore, the short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates proposed in this invention has a reasonable design for each step. By combining short-process processing with micro-alloying and using continuous casting and rolling combined with secondary annealing, the mechanical properties and corrosion resistance of the alloy plates can be effectively improved while shortening the processing flow and saving energy and costs. This achieves the goal of improving the overall performance of the alloy plates and greatly meets the application requirements of high-strength and corrosion-resistant aluminum alloy plates for ship and special vehicle structural components.

[0016] As a preferred option, in step (1), the microalloying smelting specifically involves placing the Al-Mg-Mn basic alloy and the intermediate alloy containing microalloying elements in a temperature of 720-750°C for microalloying smelting.

[0017] Preferably, in step (1), the temperature of the cast billet is 500-520℃.

[0018] Further, the mass percentage composition of the billet is: Mg 4.6%–4.7%, Mn 0.6%–0.7%, Cr 0.05%–0.25%, Ti 0.1%–0.15%, Zr 0.2%–0.3%, Sc 0–0.3%, Er 0–0.4%, with the balance being Al.

[0019] Preferably, the mass percentage composition of the billet is: Mg 4.6%–4.7%, Mn 0.6%–0.7%, Cr 0.05%–0.25%, Ti 0.1%–0.15%, Zr 0.2%–0.3%, Sc 0.2%–0.3%, Er 0.1%–0.4%, with the balance being Al.

[0020] More preferably, the mass percentage composition of the billet is: Mg 4.7%, Mn 0.6%, Cr 0.25%, Ti 0.15%, Zr 0.3%, Sc 0.2%, Er 0.1%, with the balance being Al.

[0021] Furthermore, in step (2), the deformation amount in each pass of the three-pass continuous cooling rolling deformation treatment is the same, and the total deformation amount of the three passes relative to the billet is 55% to 65%. This invention employs a three-pass continuous cooling rolling deformation treatment, which can meet the actual production requirements of continuous casting and rolling while ensuring the inheritance of the micro-alloying effect, thereby achieving the goal of improving the strength, toughness, and corrosion resistance of the final Al-Mg-Mn alloy plate through a short-process process.

[0022] Preferably, in step (2), the time for the first annealing process is 5 to 7 hours, more preferably 6 hours.

[0023] Further, in step (3), the number of cold rolling passes in the multi-pass cold rolling process is 5 to 7; the rolling temperature of the multi-pass cold rolling process is 25 to 35°C, and the deformation amount of each cold rolling pass is the same; the total deformation amount of the alloy sheet obtained after the multi-pass cold rolling process relative to the cast billet is 85% to 95%. The present invention uses multi-pass cold rolling process, which can further refine the microstructure of the sheet and increase the driving force for nano-precipitates.

[0024] Preferably, in step (3), the time for the secondary annealing process is 7 to 9 hours, more preferably 8 hours.

[0025] Furthermore, in steps (2) and (3), the cooling is air cooling to room temperature.

[0026] The present invention also provides a high-strength corrosion-resistant Al-Mg-Mn alloy plate obtained by a short-process processing method using the high-strength corrosion-resistant Al-Mg-Mn alloy plate as described above.

[0027] Preferably, the thickness of the high-strength corrosion-resistant Al-Mg-Mn alloy plate is 0.98 to 1.04 mm.

[0028] The high-strength, corrosion-resistant Al-Mg-Mn alloy sheet of this invention is prepared through a short-process machining combined with micro-alloying, and a continuous casting and rolling process combined with secondary annealing. Tests have shown that the high-strength, corrosion-resistant Al-Mg-Mn alloy sheet of this invention exhibits tensile strength and yield strength as high as 513–541 MPa and 426–469 MPa, respectively, a corrosion potential of -0.863–0.816 V, and a corrosion current density of only (1.07–2.67) × 10⁻⁶. -6 A·cm -2 With an elongation of 6.6% to 7.9%, it combines excellent strength, elongation, and corrosion resistance, effectively meeting the application requirements of high-strength and corrosion-resistant aluminum alloy sheets for structural components of ships and special vehicles. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of the short-processing method for the high-strength and corrosion-resistant Al-Mg-Mn alloy sheet of the present invention;

[0030] Figure 2 The figures show the microstructure of the Al-Mg-Mn alloy plates of Example 1 and Comparative Example 1 of the present invention, including the grain structure, the second phase structure, and the nano-precipitated phase, respectively; wherein, figures a, b, and c are the microstructure of the grain structure, the second phase structure, and the nano-precipitated phase of the plate of Comparative Example 1, respectively; and figures d, e, and f are the microstructure of the grain structure, the second phase structure, and the nano-precipitated phase of the plate of Example 1 of the present invention, respectively. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to specific embodiments and accompanying drawings, but the scope of protection of the present invention is not limited thereto.

[0032] The process flow diagrams of the short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates involved in Examples 1-5 are as follows: Figure 1 As shown, the process includes the following steps in sequence: melting, casting into a billet, three-pass continuous cooling rolling deformation, primary annealing, multi-pass cold rolling, and secondary annealing. The process will be described below with reference to specific embodiments.

[0033] Example 1

[0034] The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates in this embodiment includes the following steps:

[0035] (1) The Al-Mg-Mn basic alloy and the intermediate aluminum alloy containing microalloying elements were placed in a resistance furnace at 750℃ for microalloying smelting, and then cast to obtain a billet at 506℃ with a thickness of 10mm.

[0036] The microalloying elements are Zr, Sc, and Er; the mass percentage composition of the billet is: Mg 4.7%, Mn 0.6%, Cr 0.25%, Ti 0.15%, Zr 0.3%, Sc 0.2%, Er 0.1%, with the balance being Al.

[0037] (2) The billet obtained in step (1) is air-cooled to 405°C, and then the billet is subjected to three consecutive cooling rolling deformation treatments using the residual heat. The temperature of the first rolling is 402°C, the temperature of the second rolling is 286°C, and the temperature of the third rolling is 82°C. The deformation amount of each rolling is the same, and the total deformation amount of the three rolling is 60%, resulting in a three-rolled plate.

[0038] The three-rolled sheet was placed in a heat treatment furnace at 400℃ for a first annealing treatment for 6 hours. The nano-reinforcing phase was precipitated through the first annealing. After that, it was air-cooled to room temperature to obtain the cooled three-rolled sheet with a thickness of 4.01 mm.

[0039] (3) The three-rolled sheet after cooling in step (2) is subjected to six cold rolling processes at room temperature (25±5℃). The deformation amount of each cold rolling is the same. After the total deformation of the cold rolled sheet relative to the billet reaches 90%, the cold rolling is stopped to obtain the cold rolled sheet. Then the cold rolled sheet is placed in a heat treatment furnace at a temperature of 175℃ for a second annealing treatment for 8 hours. After that, it is air-cooled to room temperature to obtain the high-strength corrosion-resistant Al-Mg-Mn alloy sheet product of Example 1 with a thickness of 1.04mm.

[0040] Example 2

[0041] The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates in this embodiment includes the following steps:

[0042] (1) The Al-Mg-Mn basic alloy and the intermediate aluminum alloy containing microalloying elements were placed in a resistance furnace at 750℃ for microalloying smelting, and then cast to obtain a billet at 502℃ with a thickness of 10mm.

[0043] The microalloying elements are Zr and Sc; the mass percentage composition of the billet is: Mg 4.7%, Mn 0.6%, Cr 0.25%, Ti 0.15%, Zr 0.3%, Sc 0.3%, with the balance being Al.

[0044] (2) The billet obtained in step (1) is air-cooled to 405°C, and then the billet is subjected to three consecutive cooling rolling deformation treatments using the residual heat. The temperature of the first rolling is 402°C, the temperature of the second rolling is 284°C, and the temperature of the third rolling is 78°C. The deformation amount of each rolling is the same, and the total deformation amount of the three rolling is 60%, resulting in a three-rolled plate.

[0045] The three-rolled sheet was placed in a heat treatment furnace at 400℃ for a first annealing treatment for 6 hours. The nano-reinforcing phase was precipitated through the first annealing. After that, it was air-cooled to room temperature to obtain a cooled three-rolled sheet with a thickness of 4.00 mm.

[0046] (3) The three-rolled sheet after cooling in step (2) is subjected to six cold rolling processes at room temperature (25±5℃). The deformation amount of each cold rolling is the same. After the total deformation of the cold rolled sheet relative to the billet reaches 90%, the cold rolling is stopped to obtain the cold rolled sheet. Then the cold rolled sheet is placed in a heat treatment furnace at a temperature of 175℃ for a second annealing treatment for 8 hours. After that, it is air-cooled to room temperature to obtain the high-strength corrosion-resistant Al-Mg-Mn alloy sheet product of Example 2 with a thickness of 0.98mm.

[0047] Example 3

[0048] The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates in this embodiment includes the following steps:

[0049] (1) The Al-Mg-Mn basic alloy and the intermediate aluminum alloy containing microalloying elements were placed in a resistance furnace at 750℃ for microalloying smelting, and then cast to obtain a billet at 506℃ with a thickness of 10mm.

[0050] The microalloying elements are Zr, Sc, and Er; the mass percentage composition of the billet is: Mg 4.7%, Mn 0.6%, Cr 0.25%, Ti 0.15%, Zr 0.3%, Sc 0.1%, Er 0.2%, with the balance being Al.

[0051] (2) The billet obtained in step (1) is air-cooled to 405°C, and then the billet is subjected to three consecutive cooling rolling deformation treatments using the residual heat. The temperature of the first rolling is 400°C, the temperature of the second rolling is 288°C, and the temperature of the third rolling is 75°C. The deformation amount of each rolling is the same, and the total deformation amount of the three rolling is 60%, resulting in a three-rolled plate.

[0052] The three-rolled sheet was placed in a heat treatment furnace at 400℃ for a first annealing treatment for 6 hours. The nano-reinforcing phase was precipitated through the first annealing. After that, it was air-cooled to room temperature to obtain the cooled three-rolled sheet with a thickness of 4.01 mm.

[0053] (3) The three-rolled sheet after cooling in step (2) is subjected to six cold rolling processes at room temperature (25±5℃). The deformation amount of each cold rolling is the same. After the total deformation of the cold rolled sheet relative to the billet reaches 90%, the cold rolling is stopped to obtain the cold rolled sheet. Then the cold rolled sheet is placed in a heat treatment furnace at a temperature of 175℃ for a second annealing treatment for 8 hours. After that, it is air-cooled to room temperature to obtain the high-strength corrosion-resistant Al-Mg-Mn alloy sheet product of Example 3 with a thickness of 1.02mm.

[0054] Example 4

[0055] The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates in this embodiment includes the following steps:

[0056] (1) The Al-Mg-Mn basic alloy and the intermediate aluminum alloy containing microalloying elements were placed in a resistance furnace at 750℃ for microalloying smelting, and then cast to obtain a billet at 506℃ with a thickness of 10mm.

[0057] The microalloying elements are Zr and Er; the mass percentage composition of the billet is: Mg 4.7%, Mn 0.6%, Cr 0.25%, Ti 0.15%, Zr 0.3%, Er 0.3%, with the balance being Al.

[0058] (2) The billet obtained in step (1) is air-cooled to 406°C, and then the billet is subjected to three consecutive cooling rolling deformation treatments using the residual heat. The temperature of the first rolling is 402°C, the temperature of the second rolling is 284°C, and the temperature of the third rolling is 78°C. The deformation amount of each rolling is the same, and the total deformation amount of the three rolling is 60%, thus obtaining a three-rolled plate.

[0059] The three-rolled sheet was placed in a heat treatment furnace at 400℃ for a first annealing treatment for 6 hours. The nano-reinforcing phase was precipitated through the first annealing. After that, it was air-cooled to room temperature to obtain a cooled three-rolled sheet with a thickness of 4.00 mm.

[0060] (3) The three-rolled sheet after cooling in step (2) is subjected to six cold rolling processes at room temperature (25±5℃). The deformation amount of each cold rolling is the same. After the total deformation of the cold rolled sheet relative to the billet reaches 90%, the cold rolling is stopped to obtain the cold rolled sheet. Then the cold rolled sheet is placed in a heat treatment furnace at a temperature of 175℃ for a second annealing treatment for 8 hours. After that, it is air-cooled to room temperature to obtain the high-strength corrosion-resistant Al-Mg-Mn alloy sheet product of Example 4 with a thickness of 0.98mm.

[0061] Example 5

[0062] The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates in this embodiment includes the following steps:

[0063] (1) The Al-Mg-Mn basic alloy and the intermediate aluminum alloy containing microalloying elements were placed in a resistance furnace at 750℃ for microalloying smelting, and then cast to obtain a billet at 506℃ with a thickness of 10mm.

[0064] The microalloying elements are Zr and Er; the mass percentage composition of the billet is: Mg 4.7%, Mn 0.6%, Cr 0.25%, Ti 0.15%, Zr 0.2%, Er 0.4%, with the balance being Al.

[0065] (2) The billet obtained in step (1) is air-cooled to 405°C, and then the billet is subjected to three consecutive cooling rolling deformation treatments using the residual heat. The temperature of the first rolling is 403°C, the temperature of the second rolling is 287°C, and the temperature of the third rolling is 74°C. The deformation amount of each rolling is the same, and the total deformation amount of the three rolling is 60%, thus obtaining a three-rolled plate.

[0066] The three-rolled sheet was placed in a heat treatment furnace at 400℃ for a first annealing treatment for 6 hours. The nano-reinforcing phase was precipitated through the first annealing. After that, it was air-cooled to room temperature to obtain a cooled three-rolled sheet with a thickness of 4.00 mm.

[0067] (3) The three-rolled sheet after cooling in step (2) is subjected to six cold rolling processes at room temperature (25±5℃). The deformation amount of each cold rolling is the same. After the total deformation of the cold rolled sheet relative to the billet reaches 90%, the cold rolling is stopped to obtain the cold rolled sheet. Then the cold rolled sheet is placed in a heat treatment furnace at a temperature of 175℃ for a second annealing treatment for 8 hours. After that, it is air-cooled to room temperature to obtain the high-strength corrosion-resistant Al-Mg-Mn alloy sheet product of Example 5 with a thickness of 0.98mm.

[0068] Comparative Example 1

[0069] The preparation method of the Al-Mg-Mn alloy plate in this comparative example differs from that in Example 1 in that: in step (1): an Al-Mg-Mn basic alloy (composed of 4.7% Mg, 0.6% Mn, 0.25% Cr, 0.15% Ti, with the balance being Al) is used without adding microalloying elements. The alloy is directly smelted in a resistance furnace at 750°C and then cast to obtain a billet at 506°C; other steps and operations are the same as in Example 1.

[0070] Comparative Example 2

[0071] The preparation method of the Al-Mg-Mn alloy sheet in this comparative example differs from that in Example 1 in that: in step (2), an annealing process is omitted, and the three-rolled sheet is directly air-cooled to room temperature; other steps and operations are the same as in Example 1.

[0072] Comparative Example 3

[0073] The preparation method of the Al-Mg-Mn alloy plate in this comparative example differs from that in Example 1 in the following ways: In step (1), an Al-Mg-Mn basic alloy (composed of 4.7% Mg, 0.6% Mn, 0.25% Cr, 0.15% Ti, with the balance being Al) is used. No microalloying elements are added. The alloy is directly melted in a resistance furnace at 750°C and then cast to obtain a billet at 506°C. In step (2), an annealing process is omitted, and the three-rolled plate is directly air-cooled to room temperature. Other steps and operations are the same as in Example 1.

[0074] Comparative Example 4

[0075] The preparation method of the Al-Mg-Mn alloy plate in this comparative example differs from that in Example 1 in that: in step (2), the billet obtained in step (1) is first air-cooled to room temperature (25°C), and then the billet is directly subjected to three cold rolling passes. The deformation amount of each rolling pass is the same, and the total deformation amount of the three rolling passes is 60%, thus obtaining a three-rolled plate; other steps and operations are the same as in Example 1.

[0076] Comparative Example 5

[0077] The preparation method of the Al-Mg-Mn alloy sheet in this comparative example differs from that in Example 1 in that: in step (2): the billet obtained in step (1) is not air-cooled, but directly subjected to three consecutive cooling rolling deformation treatments using residual heat (506℃). The temperature of the first rolling pass is 503℃, the temperature of the second rolling pass is 454℃, and the temperature of the third rolling pass is 282℃. The deformation amount of each rolling pass is the same, and the total deformation amount of the three rolling passes is 60%, resulting in a three-rolled sheet. Other steps and operations are the same as in Example 1.

[0078] Comparative Example 6

[0079] The preparation method of the Al-Mg-Mn alloy plate in this comparative example differs from that in Example 1 in that: in step (2), the billet obtained in step (1) is air-cooled to 305°C, and then the billet is subjected to three consecutive cooling rolling deformation treatments using the residual heat. The temperature of the first rolling pass is 301°C, the temperature of the second rolling pass is 186°C, and the temperature of the third rolling pass is 51°C. The deformation amount of each rolling pass is the same, and the total deformation amount of the three rolling passes is 60%, resulting in a three-rolled plate. Other steps and operations are the same as in Example 1.

[0080] Comparative Example 7

[0081] The preparation method of the Al-Mg-Mn alloy sheet in this comparative example differs from that in Example 1 in that: in step (2): the temperature of the second rolling pass is 242°C and the temperature of the third rolling pass is 56°C; other steps and operations are the same as in Example 1.

[0082] Experimental Example 1

[0083] The microstructure of the Al-Mg-Mn alloy plates obtained in Example 1 and Comparative Example 1 of this invention was analyzed using polarized light microscopy, scanning electron microscopy, and transmission electron microscopy. Figure 2 The images show the grain structure, second phase structure, and nano-precipitated phase microstructure of the Al-Mg-Mn alloy plates of Example 1 and Comparative Example 1 of this invention; wherein, images a and d are polarized light microscope images; images b and e are SEM (scanning electron microscope) images; and images c and f are TEM (transmission electron microscope) images. Figure 2 In the diagram, a, b, and c are the microstructure diagrams of the grain structure, second phase structure, and nano-precipitated phase of the plate material of Comparative Example 1, respectively; d, e, and f are the microstructure diagrams of the grain structure, second phase structure, and nano-precipitated phase of the plate material of Example 1 of the present invention, respectively.

[0084] Depend on Figure 2It can be seen that the grain width in Figure d of Example 1 is significantly smaller than the grain size in Figure a of Comparative Example 1; the area ratio of white second phase particles in Figure e of Example 1 is significantly increased compared with that in Figure b of Comparative Example 1; in Figure f of Example 1, after two annealing processes, some second phases are spheroidized and a large number of nano-reinforcing phases are precipitated, while in Figure c of Comparative Example 1, only some second phases are spheroidized and no nano-reinforcing phases are precipitated.

[0085] Experimental Example 2

[0086] The Al-Mg-Mn alloy plates prepared in Examples 1-5 and Comparative Examples 1-7 of this invention were used to design specimens and conduct tensile property tests according to the national standard GB / T 228-2002 "Metallic Materials - Tensile Testing at Room Temperature". Three parallel tests were performed, and the electrochemical corrosion potential and corrosion current density were tested in a 3.5% NaCl solution. The performance test results of the plates from Examples 1-5 and Comparative Examples 1-7 are shown in Table 1.

[0087] Table 1. Performance test results of Al-Mg-Mn alloy plates obtained in Examples 1-5 and Comparative Examples 1-7

[0088]

[0089] As shown in Table 1, the high-strength and corrosion-resistant Al-Mg-Mn alloy sheet obtained by the preparation method of this invention has a tensile strength and yield strength as high as 513-541 MPa and 426-469 MPa, respectively, a corrosion potential of -0.863-0.816 V, and a corrosion current density of only (1.07-2.67) × 10⁻⁶. -6 A·cm -2 The elongation is 6.6%–7.9%, exhibiting excellent strength, elongation, and corrosion resistance. In contrast, the Al-Mg-Mn alloy plates prepared in Comparative Examples 1–7 exhibit problems such as low strength, low plasticity, and poor corrosion resistance, failing to achieve a balance of strength, plasticity, and corrosion resistance.

[0090] In summary, the short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates provided by this invention eliminates the need for pre-cooling and post-heating of the cast billet, significantly shortening the preparation process and saving energy and costs. Furthermore, the synergistic effect of microalloying, three-pass continuous cooling rolling, and two annealing processes promotes the precipitation of nano-reinforcing phases, effectively improving the mechanical and corrosion resistance properties of the alloy plates and endowing them with excellent comprehensive performance. This greatly satisfies the application requirements of high-strength and corrosion-resistant aluminum alloy plates for structural components in ships and special vehicles.

Claims

1. A short-process processing method for high-strength, corrosion-resistant Al-Mg-Mn alloy plates, characterized in that, Includes the following steps: (1) Microalloying elements are added to the Al-Mg-Mn basic alloy, and microalloying melting is carried out at 720-750℃, followed by casting to obtain a billet; the microalloying elements are selected from two or three of Zr, Sc, and Er; the mass percentage composition of the billet is: Mg 4.6%-4.7%, Mn 0.6%-0.7%, Cr 0.05%-0.25%, Ti 0.1%-0.15%, Zr 0.2%-0.3%, Sc 0-0.3%, Er 0-0.4%, with the balance being Al; (2) Cool the billet obtained in step (1) to 400-410℃, and then use the residual heat to perform three consecutive cooling rolling deformation treatment on the billet to obtain a three-rolled plate. Then, anneal the three-rolled plate at 390-410℃ and then cool it. In the three consecutive cooling rolling deformation treatment, the temperature of the first rolling is 400-410℃, the temperature of the second rolling is 280-290℃, and the temperature of the third rolling is 70-85℃. (3) The plate after cooling in step (2) is subjected to multiple cold rolling processes, and then subjected to secondary annealing at 170-180℃, followed by cooling, to obtain the high-strength corrosion-resistant Al-Mg-Mn alloy plate.

2. The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates as described in claim 1, characterized in that, In step (1), the microalloying smelting specifically involves placing the Al-Mg-Mn basic alloy and the intermediate alloy containing microalloying elements in a temperature of 720-750℃ for microalloying smelting.

3. The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates as described in claim 1, characterized in that, The mass percentage composition of the billet is: Mg 4.7%, Mn 0.6%, Cr 0.25%, Ti 0.15%, Zr 0.3%, Sc 0.2%, Er 0.1%, with the balance being Al.

4. The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates as described in claim 1, characterized in that, In step (2), the deformation amount of each pass of the three-pass continuous cooling rolling deformation treatment is the same, and the total deformation amount of the three passes relative to the billet is 55% to 65%.

5. The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates as described in claim 1, characterized in that, In step (2), the annealing process takes 5 to 7 hours.

6. The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates as described in claim 1, characterized in that, In step (3), the number of cold rolling passes in the multi-pass cold rolling process is 5 to 7; the rolling temperature of the multi-pass cold rolling process is 20 to 30°C, and the deformation amount of each cold rolling pass is the same; the total deformation amount of the alloy plate obtained after the multi-pass cold rolling process relative to the cast billet is 85% to 95%.

7. The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates as described in claim 1, characterized in that, In step (3), the secondary annealing process takes 7 to 9 hours.

8. The short-process processing method for high-strength and corrosion-resistant Al-Mg-Mn alloy plates as described in claim 1, characterized in that, In steps (2) and (3), the cooling is air cooling to room temperature.

9. A high-strength, corrosion-resistant Al-Mg-Mn alloy sheet obtained by a short-process processing method using the high-strength, corrosion-resistant Al-Mg-Mn alloy sheet as described in any one of claims 1 to 8.

10. The high-strength, corrosion-resistant Al-Mg-Mn alloy plate as described in claim 9, characterized in that, The thickness of the high-strength and corrosion-resistant Al-Mg-Mn alloy plate is 0.98–1.04 mm.

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