Production method of aluminum-magnesium alloy cold-rolled sheet strip with high specific strength and good plasticity

Abstract

The invention discloses a production method of an aluminum-magnesium alloy cold-rolled sheet strip with high specific strength and good plasticity. The problem that the aluminum-magnesium alloy cold-rolled sheet strip cannot achieve high strength, high specific strength and good plasticity at the same time through a short technological process can be solved. The production method comprises the following working procedures: casting, saw cutting, surface milling, heating, hot rolling, cold rolling, annealing and flattening, wherein an aluminum magnesium alloy cast ingot comprises the following chemical components in percentage by mass: less than or equal to 0.15% of Si, less than or equal to 0.30% of Fe, less than or equal to 0.10% of Cu, 0.10-0.25% of Mn, 5.7-6.2% of Mg, 0.01-0.08% of Cr, less than or equal to 0.10% of Zn, 0.01-0.05% of Ti, less than or equal to 0.05% of a single impurity element, less than or equal to 0.15% of other impurity elements and the balance of Al. By regulating and controlling the alloy element content, the heating parameters, the hot rolling finishing temperature, the cold rolling total machining rate and the finished product annealing parameters, the tensile strength Rm is larger than or equal to 370 MPa, the specific strength is larger than or equal to 0.14 kNm / g, the specified non-proportional extension strength Rp0.2 is larger than or equal to 260 MPa, the percentage elongation after fracture is larger than or equal to 13%, and the aluminum plate strip is bent by 90 degrees with the thickness being 1 time that of the aluminum plate strip without cracking.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum-magnesium alloy manufacturing, and in particular to a method for producing an aluminum-magnesium alloy cold-rolled sheet strip with high specific strength and good plasticity. Background Art

[0002] Aluminum-magnesium deformed aluminum-magnesium alloys have high strength and good formability, corrosion resistance, welding performance and fatigue strength. Aluminum-magnesium alloy plates and strips in different states are widely used in transportation, machinery manufacturing, electronic appliances, architectural decoration and other fields. With the increasing requirements for energy conservation and emission reduction, high specific strength is required for aluminum-magnesium alloy plates and strips used in transportation and other fields. The subsequent processing methods of aluminum-magnesium alloy plates and strips mainly include bending, biting, deep drawing, bulging, etc. In order to ensure smooth processing and forming, high plasticity indicators of plates and strips are required. Therefore, aluminum-magnesium alloy plates and strips with high specific strength and good plasticity have market demand and engineering value.

[0003] Chinese patent CN116240433A discloses a high-strength aluminum strip and a preparation method thereof, by controlling the addition ratio of elements such as Mg, Mn, Zn, Fe and the upper limit of the content of impurity elements such as Si, the aluminum-magnesium alloy ingot is subjected to hot rolling, cold rolling, intermediate annealing, finished product cold rolling and other processes and reasonable process parameters are matched to obtain high-strength aluminum strip, but the product is not subjected to finished product annealing treatment, and cracking is prone to occur during subsequent forming processing, and the impurity element content is low and the production cost is high. Chinese patent CN105525167A discloses an ultra-high-strength aluminum-magnesium alloy strip for anodizing and a preparation method thereof, by controlling the addition ratio of elements such as Mg, Cu and the upper limit of the content of impurity elements such as Si and Fe, as well as hot rolling, cold rolling, intermediate annealing, finished product cold rolling, finished product annealing and other process parameters, to obtain an aluminum-magnesium alloy strip with higher yield strength and good anodizing effect, but the product has a low impurity element content and a high production cost, and if the intermediate annealing method is adopted for production, there are more processes. Summary of the invention

[0004] In view of the above shortcomings, the present invention provides a method for producing aluminum-magnesium alloy cold-rolled strip with high specific strength and good plasticity. By reasonably matching the alloy element content, hot rolling final rolling temperature, cold rolling total processing rate and annealing process, a method for producing aluminum-magnesium alloy cold-rolled strip with high specific strength, good plasticity and bending performance is provided. The product of the present invention can achieve a tensile strength Rm ≥ 370MPa, a specific strength ≥ 0.14kNm / g, and a non-proportional elongation strength Rp 0.2 ≥260MPa, elongation after fracture ≥13%, can be bent at 90° with a bending radius of 1 times the thickness of the aluminum plate and strip without cracking. The specific technical solution is as follows:

[0005] A cold-rolled aluminum-magnesium alloy strip with high specific strength and good plasticity, the production method of which comprises the following steps: melting and casting→sawing→milling→heating→hot rolling→cold rolling→annealing→leveling.

[0006] In the melting and casting process, the mass percentages of the chemical components of the aluminum-magnesium alloy are: Si≤0.15%, Fe≤0.30%, Cu≤0.10%, Mn 0.10-0.25%, Mg 5.7-6.2%, Cr 0.01-0.08%, Zn≤0.10%, Ti 0.01-0.05%, other impurity elements individually ≤0.05%, other impurity elements in total ≤0.15%, and the rest is Al.

[0007] In the heating process, the heating temperature of the aluminum-magnesium alloy ingot is 480-520° C., and the insulation time is 2-8 hours.

[0008] In the hot rolling process, the hot rolling final rolling temperature is 320-360° C., and the hot rolled coil thickness is based on the finished product thickness with a reserved cold rolling processing rate of 50-70%.

[0009] In the hot rolling process, the aluminum-magnesium alloy ingot is hot rolled to a thickness of 2.5 to 7.0 mm.

[0010] In the cold rolling process, the hot rolled coil is cold rolled to 0.75-3.5 mm, with a total processing rate of 50-70%.

[0011] In the annealing process, the aluminum coil annealing temperature is 160-200° C., and the heat preservation time is 3-6 hours.

[0012] In the leveling step, the aluminum coil is leveled by a stretch-bending leveler or the aluminum coil is leveled by a cross-cutting machine and then sheared into a plate.

[0013] Aluminum-magnesium alloy is a non-heat-treatable aluminum alloy. Its strength and plasticity are mainly affected by alloy composition, degree of work hardening produced by rolling process, degree of recrystallization produced by annealing process, etc. Adding appropriate proportions of Mn, Mg and Cr to aluminum-magnesium alloy can play a significant role in solid solution strengthening and improve strength without causing excessive decrease in plasticity. During the cold rolling process, aluminum-magnesium alloy will produce work hardening. As the total cold rolling processing rate increases, the strength of aluminum-magnesium alloy sheet and strip increases, but the plasticity and bending properties decrease. Recovery and recrystallization will occur during annealing after cold rolling. Within a certain range, the higher the annealing temperature and the longer the holding time, the higher the degree of recovery and recrystallization, the lower the strength of aluminum sheet and strip, and the plasticity and bending properties increase. Therefore, by reasonably controlling the alloy element content, hot rolling final rolling temperature, total cold rolling processing rate and annealing process, aluminum-magnesium alloy cold-rolled sheet and strip with high strength and specific strength, good plasticity and bending properties can be produced.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention prepares an aluminum-magnesium alloy cold-rolled sheet and strip with high specific strength and good plasticity through a series of processes of melting, sawing, milling, heating, hot rolling, cold rolling, annealing, and leveling. The thickness of the aluminum-magnesium alloy cold-rolled sheet and strip is 0.75 to 3.5 mm. By reasonably controlling the alloy element content, hot rolling final rolling temperature, cold rolling total processing rate, and annealing process, the product tensile strength Rm ≥ 370 MPa, specific strength ≥ 0.14 kNm / g, and the non-proportional elongation strength Rp is specified. 0.2 ≥260MPa, good plasticity and bending properties, elongation after fracture ≥13%, can be bent 90° with a bending radius of 1 times the thickness of the aluminum plate and strip without cracking.

[0016] 2. The present invention controls the optimal ratio of Mn 0.10-0.25%, Mg 5.7-6.2%, and Cr 0.01-0.08%, so that the aluminum-magnesium alloy can achieve high strength and good plasticity, play a significant solid solution strengthening role to improve the strength, and at the same time does not cause excessive decrease in plasticity; the heating temperature of the aluminum-magnesium alloy ingot is controlled at 480-520°C, and the holding time is 2-8 hours, so that the ingot can be fully and evenly heated, avoiding the problems of uneven heating and unstable performance caused by too high or too low heating temperature and improper holding time, and providing good organizational conditions for the hot rolling process; the hot rolling final rolling temperature is controlled at 320-360°C, combined with a total cold rolling processing rate of 50-70%, and then combined with an annealing process with a temperature of 160-200°C and a holding time of 3-6 hours, and the degree of recovery and recrystallization is controlled within a certain range, so that plate and strip products with high strength and specific strength, good plasticity and bending performance can be produced.

[0017] 3. The requirements for Si, Fe and other impurity elements are wide, the annealing process is simple and the production cost is low. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0019] Example 1

[0020] This embodiment is a method for producing cold-rolled aluminum-magnesium alloy strips with high specific strength and good plasticity, which includes the following production steps: melting and casting → sawing → milling → heating → hot rolling → cold rolling → annealing → leveling.

[0021] (1) Melting and casting: The raw materials are placed in a melting furnace for melting and casting. The mass percentages of chemical elements in the aluminum-magnesium alloy ingot after melting and casting are shown below.

[0022]

[0023] (2) Sawing and milling: The aluminum-magnesium alloy ingot is sawed and milled to obtain a milled aluminum-magnesium alloy ingot.

[0024] (3) Heating: heating the milled aluminum-magnesium alloy ingot to 500° C. and then keeping the temperature for 2 hours.

[0025] (4) Hot rolling: The aluminum-magnesium alloy ingot subjected to the heat treatment is hot rolled, the hot rolling final rolling temperature is 340° C., and the hot rolled billet thickness is 5.0 mm.

[0026] (5) Cold rolling: The hot rolled billet is rolled to 2 mm, with a total processing rate of 60%.

[0027] (6) Annealing: coil temperature 160 ~ 200 ° C, holding time 3 to 6 hours.

[0028] (7) Leveling: Use a straightening machine to level the aluminum coil and then cut it into plates and strips.

[0029]

[0030]

[0031] From the data in the table above, it can be seen that the finished product annealing temperature is within the range of 160-200℃, Rm≥381MPa, Rp 0.2 ≥271MPa, A≥14%, specific strength≥0.144, can be bent 90° with a bending radius of 1 times the thickness of the aluminum plate and strip without cracking.

[0032] Example 2

[0033] This embodiment is a method for producing cold-rolled aluminum-magnesium alloy strips with high specific strength and good plasticity, which includes the following production steps: melting and casting → sawing → milling → heating → hot rolling → cold rolling → annealing → leveling.

[0034] (1) Melting and casting: The raw materials are placed in a melting furnace for melting and casting. The mass percentages of chemical elements in the aluminum-magnesium alloy ingot after melting and casting are shown below.

[0035]

[0036] (2) Sawing and milling: The aluminum-magnesium alloy ingot is sawed and milled to obtain a milled aluminum-magnesium alloy ingot.

[0037] (3) Heating: The milled aluminum-magnesium alloy ingot is heated to 520° C. and then kept at this temperature for 5 hours.

[0038] (4) Hot rolling: The aluminum-magnesium alloy ingot subjected to the heat treatment is hot rolled, the hot rolling final rolling temperature is 320° C., and the hot rolled billet thickness is 2.5 mm.

[0039] (5) Cold rolling: The hot rolled billet is rolled to 0.75 mm, with a total processing rate of 70%.

[0040] (6) Annealing: coil temperature 160 ~ 200 ° C, holding time 3 to 6 hours.

[0041] (7) Leveling: Use a cross-cutting machine to level the aluminum coil and then cut it into plates and strips.

[0042]

[0043]

[0044] From the data in the table above, we can see that the annealing temperature of the finished product is within the range of 160-200℃, Rm≥390MPa, Rp 0.2 ≥283MPa, A≥13%, specific strength≥0.148, can be bent 90° with a bending radius of 1 times the thickness of the aluminum plate and strip without cracking.

[0045] Example 3

[0046] This embodiment is a method for producing a cold-rolled aluminum-magnesium alloy strip with high specific strength and good plasticity, comprising the following production steps: melting and casting → sawing → milling → heating → hot rolling → cold rolling → annealing → leveling;

[0047] (1) Melting and casting: The raw materials are placed in a melting furnace for melting and casting. The mass percentages of chemical elements in the aluminum-magnesium alloy ingot after melting and casting are shown below.

[0048]

[0049] (2) Sawing and milling: sawing and milling the aluminum-magnesium alloy ingot to obtain a milled aluminum-magnesium alloy ingot;

[0050] (3) Heating: heating the milled aluminum-magnesium alloy ingot to 480° C. and then keeping the temperature for 8 hours.

[0051] (4) Hot rolling: The aluminum-magnesium alloy ingot subjected to the heat treatment is hot rolled, the hot rolling final rolling temperature is 360° C., and the hot rolled billet thickness is 7.0 mm.

[0052] (5) Cold rolling: The hot rolled billet is rolled to 3.5 mm, with a total processing rate of 50%.

[0053] (6) Annealing: coil temperature 160 ~ 200 ° C, holding time 3 to 6 hours.

[0054] (7) Leveling: Use a straightening machine to level the aluminum coil and then cut it into plates and strips.

[0055]

[0056]

[0057] From the data in the table above, it can be seen that the finished product annealing temperature is within the range of 160-200℃, Rm≥374MPa, Rp 0.2 ≥262MPa, A≥15%, specific strength≥0.142, and can be bent at 90° with a bending radius of 1 times the thickness of the aluminum plate and strip without cracking.

[0058] On the basis of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 tests are added. The difference between Comparative Example 1, Comparative Example 2 and Comparative Example 3 and Example 1 is only that the contents of Mn, Mg and Cr are changed, and other processes and parameters remain unchanged. The mass percentages of chemical elements of the aluminum-magnesium alloy ingot after melting and casting are shown in the following table.

[0059]

[0060] The test results of Comparative Example 1 are shown in the following table:

[0061]

[0062] From the above table and the experimental results of Example 1, it can be seen that the comparative examples Rm and Rp 0.2 Both increase, the product strength increases, but the elongation after fracture decreases, the plasticity decreases, and the production cost also increases.

[0063] The test results of Comparative Example 2 are shown in the following table:

[0064]

[0065] The test results of Comparative Example 3 are shown in the following table:

[0066]

[0067]

[0068] From the above table and the experimental results of Example 1, it can be seen that the Rm and Rp of Comparative Examples 2 and 3 are 0.2 The solid solution strengthening effect of the product is reduced, the strength is reduced, the elongation after fracture of Example 2 is reduced, and the elongation after fracture of Example 3 remains unchanged. It can be seen that the content ratio of Mn, Mg and Cr in Example 1 is the best.

[0069] Comparative Example 4

[0070] This embodiment is a method for producing cold-rolled aluminum-magnesium alloy strips with high specific strength and good plasticity, which includes the following production steps: melting and casting → sawing → milling → heating → hot rolling → cold rolling → annealing → leveling.

[0071] (1) Melting and casting: The raw materials are placed in a melting furnace for melting and casting. The mass percentages of the chemical elements of the aluminum-magnesium alloy ingot after melting and casting are as follows.

[0072]

[0073] (2) Sawing and milling: The aluminum-magnesium alloy ingot is sawed and milled to obtain a milled aluminum-magnesium alloy ingot.

[0074] (3) Heating: heating the milled aluminum-magnesium alloy ingot to 500° C. and then keeping the temperature for 2 hours.

[0075] (4) Hot rolling: The aluminum-magnesium alloy ingot subjected to the heat treatment is hot rolled, the hot rolling final rolling temperature is 300° C., and the hot rolled billet thickness is 5.0 mm.

[0076] (5) Cold rolling: The hot rolled billet is rolled to 2 mm, with a total processing rate of 80%.

[0077] (6) Annealing: coil temperature 120 ~ 160 ° C, holding time 3 ~ 6 hours.

[0078] (7) Leveling: Use a tension and bending straightening machine to level the aluminum coil to the required straightness and then cut it into plates and strips.

[0079]

[0080]

[0081] Comparative Example 5

[0082] This embodiment is a method for producing cold-rolled aluminum-magnesium alloy strips with high specific strength and good plasticity, which includes the following production steps: melting and casting → sawing → milling → heating → hot rolling → cold rolling → annealing → leveling.

[0083] (2) Melting and casting: The raw materials are placed in a melting furnace for melting and casting. The mass percentages of the chemical elements of the aluminum-magnesium alloy ingot after melting and casting are as follows.

[0084]

[0085] (2) Sawing and milling: The aluminum-magnesium alloy ingot is sawed and milled to obtain a milled aluminum-magnesium alloy ingot.

[0086] (3) Heating: heating the milled aluminum-magnesium alloy ingot to 500° C. and then keeping the temperature for 2 hours.

[0087] (4) Hot rolling: The aluminum-magnesium alloy ingot subjected to the heat treatment is hot rolled, the hot rolling final rolling temperature is 380° C., and the hot rolled billet thickness is 5.0 mm.

[0088] (5) Cold rolling: The hot rolled billet is rolled to 2 mm, with a total processing rate of 80%.

[0089] (6) Annealing: coil temperature 160 ~ 200 ° C, holding time 1 to 4 hours.

[0090] (7) Leveling: Use a tension and bending straightening machine to level the aluminum coil to the required straightness and then cut it into plates and strips.

[0091]

[0092]

[0093] It can be seen from the experimental results of Comparative Example 4, Comparative Example 5 and Example 1 that the aluminum-magnesium alloy will produce work hardening during the cold rolling process. As the total cold rolling processing rate increases, the strength of the aluminum-magnesium alloy sheet and strip increases, but the plasticity and bending properties decrease. Recovery and recrystallization will occur during annealing after cold rolling. Within a certain range, the higher the annealing temperature and the longer the holding time, the greater the degree of recovery and recrystallization, the lower the strength of the aluminum sheet and strip, and the better the plasticity and bending properties. However, the lower the annealing temperature and the shorter the holding time does not necessarily mean the higher the strength of the aluminum sheet and strip. The annealing process needs to be coordinated with the hot rolling final rolling temperature to achieve the best performance effect under the best cost-effective conditions.

[0094] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for producing cold-rolled aluminum-magnesium alloy strip with high specific strength and good plasticity, characterized in that: The method comprises the following steps: melting and casting → sawing → milling → heating → hot rolling → cold rolling → annealing → leveling; the aluminum-magnesium alloy ingot obtained by melting and casting the metal raw material is subjected to sawing and milling treatment, and then subjected to heating treatment, and then hot rolling to obtain a hot-rolled coil, and the hot-rolled coil is cold-rolled to make an aluminum-magnesium alloy coil, and then annealed and leveled and then sheared into a plate and strip to obtain an aluminum-magnesium alloy plate and strip finished product; In the melting and casting process, the mass percentages of the chemical components of the aluminum-magnesium alloy ingot are: Si≤0.15%, Fe≤0.30%, Cu≤0.10%, Mn 0.10-0.25%, Mg 5.7-6.2%, Cr 0.01-0.08%, Zn≤0.10%, Ti0.01-0.05%, other impurity elements individually ≤0.05%, other impurity elements in total ≤0.15%, and the rest is Al.

2. The method for producing cold-rolled aluminum-magnesium alloy strip with high specific strength and good plasticity according to claim 1, characterized in that: In the heating process, the heating temperature of the aluminum-magnesium alloy ingot is 480-520° C., and the insulation time is 2-8 hours.

3. The method for producing cold-rolled aluminum-magnesium alloy strip with high specific strength and good plasticity according to claim 1, characterized in that: In the hot rolling process, the hot rolling finishing temperature is 320-360°C.

4. The method for producing cold-rolled aluminum-magnesium alloy strip with high specific strength and good plasticity according to claim 1, characterized in that: In the cold rolling process, the hot rolled coil is cold rolled to 0.75-3.5 mm, and the total cold rolling processing rate is 50-70%.

5. The method for producing cold-rolled aluminum-magnesium alloy strip with high specific strength and good plasticity according to claim 1, characterized in that: In the annealing process, the annealing temperature of the aluminum-magnesium alloy coil is 160-200° C., and the insulation time is 3-6 hours.

6. The method for producing cold-rolled aluminum-magnesium alloy strip with high specific strength and good plasticity according to claim 1, characterized in that: In the leveling step, the aluminum-magnesium alloy coil is leveled by a stretch-bending leveler or the aluminum-magnesium alloy coil is leveled by a cross-cutting machine and then sheared into plates and strips.

7. The method for producing cold-rolled aluminum-magnesium alloy strip with high specific strength and good plasticity according to claim 2, characterized in that: In the heating process, the heating and heat preservation time of the aluminum-magnesium alloy ingot is 2 to 8 hours.

8. The method for producing cold-rolled aluminum-magnesium alloy strip with high specific strength and good plasticity according to claim 3, characterized in that: In the hot rolling process, the aluminum-magnesium alloy ingot is hot rolled to a thickness of 2.5 to 7.0 mm.

9. A cold-rolled aluminum-magnesium alloy sheet or strip with high specific strength and good plasticity produced by the production method as claimed in any one of claims 1 to 8.

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