EP4656747A1

EP4656747A1 - Manufacturing method for 5-series aluminum alloy sheet, and aluminum alloy sheet

Info

Publication number: EP4656747A1
Application number: EP24746987.7A
Authority: EP
Inventors: Xini YUAN; Lingyong CAO; Gaohui CAO; Haitong HE; Xiao Hu; Bing Yang
Original assignee: Baoshan Iron and Steel Co Ltd
Current assignee: Baoshan Iron and Steel Co Ltd
Priority date: 2023-01-28
Filing date: 2024-01-26
Publication date: 2025-12-03
Also published as: EP4656747A4; CN118406906A; WO2024156280A1; JP2026508834A; KR20250141705A

Abstract

A manufacturing method for a 5-series aluminum alloy sheet, comprising the steps of: (1) performing smelting and casting; (2) performing hot rolling: controlling a heating temperature to be 500-540°C, maintaining the temperature for 2-10 h, and enabling an initial rolling temperature of rough hot rolling to be 500°C-540°C; (3) performing cold rolling; (4) performing intermediate annealing, so that the average grain size after intermediate annealing is 15 µm-40 µm; and (5) performing secondary cold rolling: controlling the secondary cold rolling reduction to be 6%-20%. Further disclosed is a 5-series aluminum alloy sheet manufactured by using the method, wherein the manufactured 5-series aluminum alloy sheet has high strength and high bending performance.

Description

Technical Field

The present disclosure relates to a metallic material and a method for manufacturing the same, particularly to an aluminum alloy material and a method for manufacturing the same.

Background

The main alloying element of 5 series aluminum alloy sheets is Mg. Since 5 series aluminum alloy sheets have a wide and adjustable strength range, excellent elongation, forming properties and corrosion resistance, they are widely used in applications such as outer panels of buses, chassis and cabinets, hardware, internal components, and power supply housings, etc.
The 5 series aluminum alloys represented by 5052, 5754, etc., are not reinforceable by heat-treatment and are mainly strengthened by solid solution strengthening and work hardening. The 5 series aluminum alloys exhibit excellent formability and bending performance in the fully annealed state (O state), but have relatively low strength. In applications requiring higher strength, alloys in incomplete annealing (H2x) or stabilization annealing (H3x) states are generally used, such as 5052-H32/H22, 5052-H34/H24, 5754-H32/H22, and 5754-H34/H24. These states typically involve first processing the material to increase its work hardening level beyond the specifications for finished products, followed by incomplete annealing to reduce the strength to the specified index (H2x) or subjecting the excessive work-hardened material to low-temperature heat treatment to reduce the strength to the specified index (H3x).
Currently, the research on the process of 5-series aluminum alloys mainly focuses on the process optimization of incomplete annealing H22 and stabilization H32. For example, the Chinese patent document with a publication number of CN109082615A, published on December 25, 2018 , titled "A Stabilization Treatment Process for 5052 Aluminum Alloy," has disclosed that: after a 5052-aluminum alloy ingot was sawed and milled, the sawed and milled 5052 aluminum alloy ingot was sent into a heating furnace and heated at 480-520°C for 3-5 hours. The heated 5052 aluminum alloy ingot was then taken out for hot rolling. After hot rolling, the intermediate sheet was cooled to room temperature and cold rolled, with a cold rolling deformation rate of 30-70%. The cold-rolled aluminum alloy sheet was then subjected to stabilization annealing at a temperature of 180-250°C for a time period of 2-8 hours.
However, the 5 series aluminum alloys produced using H2x and H3x processes undergo excessive work hardening during the cold rolling process, resulting in fibrous deformation structures. In subsequent incomplete annealing (H2x) and stabilization annealing (H3x) processes, fibrous deformation structures still exist, and there remains a high dislocation density within the grains. This leads to poor bending performance, often resulting in cracking when used in parts with stringent bending forming requirements, such as chassis and cabinets, outer panels of buses, and internal components.
Therefore, it is desired to provide a method that can produce 5-series aluminum alloy sheets having both excellent bending performance and high strength.

Summary

One of the objects of the present disclosure is to provide a manufacturing method for a 5-series aluminum alloy sheet, which can produce an aluminum alloy sheet that has both high strength and excellent bending performance.
As described herein, the 5 series aluminum alloy sheet, also known as Al-Mg series alloy aluminum sheet, is an aluminum alloy with Mg as the main alloying element. The 5 series aluminum alloy grades in the market include but are not limited to: 5005, 5050, 5052, 5056, 5083, 5086, 5154, 5182, 5252, 5254, 5356, 5454, 5456, 5457, 5652, 5657, 5754, 5A02, 5A03, 5A05, 5A06, and 5A12, etc.
To achieve the above purpose, the present disclosure provides a manufacturing method for the 5-series aluminum alloy sheet, which comprises steps of:

(1) smelting and casting;
(2) hot rolling: the heating temperature is controlled at 500-540°C and held for 2-10h, and the initial rolling temperature of hot rough rolling is 500-540°C;
(3) primary cold rolling;
(4) intermediate annealing, so that the average grain size is 15µm-40µm after intermediate annealing;
(5) secondary cold rolling: wherein the deformation rate is controlled to be 6%-20%.

The manufacturing method of the present disclosure optimizes the hot rolling homogenization heating system and regulates the cold rolling and intermediate annealing processes to control the microstructure of the sheet, thereby achieving high strength and high bending performance. In particular:
The hot rolling heating temperature is controlled at 500-540°C with a holding time of 2-10 hours, and the initial rolling temperature of hot rough rolling is simultaneously controlled at 500-540°C, because homogenization can eliminate intragranular segregation during the semi-continuous casting process, eliminate casting internal stresses, and promote the re-dissolution of the soluble iron-rich phase and the β-Al₃Mg₂ phase. If the heating temperature is lower than 500°C, it can lead to insufficient re-dissolution of the iron-rich phase and β-Al₃Mg₂ phase, resulting in coarse iron-rich phase and β-Al₃Mg₂ easily remaining in the grains and at the grain boundaries of the final product, creating stress concentrations and crack sources during bending deformation, which deteriorates the bending performance. If the heating temperature is higher than 540°C, it can easily cause the material to be overheated during the heating process, which worsens the plasticity of the material.
In the present disclosure, the initial rolling temperature of rough rolling is 500-540°C, instead of the conventional process of cooling the slab before exiting the furnace and rolling. The goal is also to suppress the precipitation of β-Al₃Mg₂ at the grain boundaries.
The average grain size after intermediate annealing should be 15µm-40µm, because if the grain size is too small, it can lead to excessively small grain size in a final product, which is detrimental to bending performance; if the grain size is too large, it can result in an uneven grain size distribution.
In addition, the secondary cold rolling deformation rate should be 6%-20%, because if the secondary cold rolling deformation rate is too small, it may lead to insufficient work hardening and low strength; if the secondary cold rolling deformation rate is too large, it may cause intragranular dislocation densities and too many shear bands, worsening the bending performance. In some embodiments, the secondary cold rolling deformation rate is 6.8% to 19%.
Further, in step (2) of the manufacturing method of the present disclosure, the coiling temperature of hot rolling is controlled at 300-350°C.
Controlling the coiling temperature of hot rolling at 300-350°C is to ensure that the hot rolled structure is a completely recrystallized structure, thereby further providing excellent plasticity. If the coiling temperature of hot rolling is below 300°C, it will lead to insufficient recrystallization, resulting in deformation microstructures in the material, which decreases processability; if the coiling temperature exceeds 350°C, it will cause defects such as sticking injuries on the surface of the coils, reducing the surface quality of the material.
Further, in step (3) of the manufacturing method of the present disclosure, the cold rolling deformation rate is controlled at 30%-90%.
Controlling the primary cold rolling deformation rate at 30-90% is to further ensure that the average grain size after intermediate annealing is 15-40µm.
In some embodiments, in step (4), intermediate annealing is conducted by using a continuous annealing line, where the continuous annealing line has an annealing temperature of 400-540°C and a holding time of 5s-60s.
In some further embodiments, in step (4), intermediate annealing is conducted by using a box furnace, wherein the box furnace has an annealing temperature of 300-360°C and a holding time of 2-10h.
In some embodiments, in step (1), melting-semi-continuous casting is adopted to obtain aluminum alloy ingots.
In some embodiments, there is no annealing step after step (5).
Another object of the present disclosure is to provide a 5-series aluminum alloy sheet which has both high strength and excellent bending performance.
Based on the above purpose, the present disclosure also provides a 5-series aluminum alloy sheet prepared by the aforementioned manufacturing method.
Further, the 5-series aluminum alloy sheet of the present disclosure has an average grain aspect ratio of 1-4, with no obvious shear bands within the grains. Further, the area proportion of shear bands within the grains of the 5-series aluminum alloy sheet of the present disclosure is ≤5%, preferably ≤3%, more preferably ≤1%.
Further, the thickness of the 5-series aluminum alloy sheet of the present disclosure is 0.2-3mm.
Further, for the 5-series aluminum alloy sheet of the present disclosure with a thickness t that meets 0.2≤t<0.5mm, when the bend radius is 0t, there is no cracking at 90° bending; for the 5 series aluminum alloy sheet with a thickness t that meets 0.5≤t<1mm, when the bending radius is 0.5t, there is no cracking at 90° bending; for the 5 series aluminum alloy sheet with a thickness of 1mm-3mm, when the bending radius is ≤0.5mm, there is no cracking at 90° bending, where t represents thickness.
Further, the 5-series aluminum alloy sheet of the present disclosure has a yield strength of 130-210MPa, a tensile strength of 210-270 MPa, and an elongation of ≥8%. In some embodiments, the 5-series aluminum alloy sheet of the present disclosure has an elongation of ≥8%, such as 10~16%.
Further, the 5-series aluminum alloy sheet of the present disclosure comprises Al and unavoidable impurities. In addition, it also comprises each chemical element in mass percentage as follows: Si≤0.15%, Fe≤0.5%, Cu≤0.2%, Mn≤0.5%, Mg: 2.0~5.0%, Cr≤0.5%, Zn≤0.05%, Ti: 0.01~0.05%.
Further, the 5-series aluminum alloy sheet of the present disclosure comprises Al and unavoidable impurities. In addition, it also comprises each chemical element in mass percentage as follows:
Si≤0.15%, Fe≤0.5%, Cu≤0.2%, Mn≤0.5%, Mg: 2.0~4.0%, Cr≤0.5%, Zn≤0.05%, Ti: 0.01~0.05%.
Still further, the mass percentages of the chemical elements of the 5-series aluminum alloy sheet of the present disclosure are as follows: Si≤0.15%, Fe≤0.5%, Cu≤0.2%, Mn≤0.5%, Mg: 2.0~5.0%, Cr≤0.5%, Zn≤0.05%, Ti: 0.01~0.05%; with a balance of Al and unavoidable impurities.
Still further, the mass percentages of the chemical elements of the 5-series aluminum alloy sheet of the present disclosure are as follows: Si≤0.15%, Fe≤0.5%, Cu≤0.2%, Mn≤0.5%, Mg: 2.0~4.0%, Cr≤0.5%, Zn≤0.05%, Ti: 0.01~0.05%; with a balance of Al and unavoidable impurities.
Among the unavoidable impurities, the content of a single impurity is ≤ 0.05%, and the total content of impurities ≤ 0.15%.
In some embodiments, in the 5-series aluminum alloy sheet of the present disclosure, the Si content is 0.08~0.15%; the Fe content is 0.15~0.50%; the Cu content is 0.04~0.20%; the Mn content is 0.01~0.5%; the Cr content is 0.01~0.5%; and the Zn content is 0.01~0.05%.
The manufacturing method for the 5-series aluminum alloy sheet of the present disclosure has the following advantages and beneficial effects:
The manufacturing method for the 5-series aluminum alloy sheet of the present disclosure is a short-process preparation method, so it can greatly reduce the production cost.
The process path provided by the present disclosure only needs intermediate complete annealing once, which is different from the prior technology that adopts annealing twice. Conventional 5052/5754-H32 products need to be subjected to primary cold rolling- intermediate annealing-secondary cold rolling, and final product annealing, that is, double annealing is required, wherein the secondary annealing process window is narrow. Moreover, because the conventional 5052/5754-H22 products have a narrow process window when the final product undergoes an incomplete annealing and the annealing processes of products with different deformation rates are different, it is not conducive to batch production. In contrast, the present disclosure only needs to carry out intermediate annealing treatment, so coils with different thickness specifications, different coil diameter and width can be produced in batches with low cost and wide process window. Therefore, the production and manufacturing cost in the technical solution of the present disclosure is greatly reduced compared with the 5052/5754-H32 products.
The 5 series aluminum alloy made by the present disclosure has both high strength and excellent elongation, especially excellent bending performance. It is especially suitable for the application fields such as outer panels of buses, chassis and cabinets, internal components and other applications that require particularly strict bending performance.
In some embodiments, the 5 series aluminum alloy sheet of the present disclosure has a yield strength of 130-210MPa, a tensile strength of 210-270MPa, an elongation of ≥8%, no cracking in a sheet with a thickness of 0.2-0.5mm at 90° bending when the bending radius is 0t, no cracking in a sheet with a thickness of 0.5-1mm at 90° bending when the bending radius is 0.5t, and no cracking in a sheet with a thickness of 1-3mm at 90° bending when the bending radius is ≤0.5mm.

Description of the drawings

Fig. 1 shows the microstructure photograph of the 5 series aluminum alloy sheet of Example 1 of the present disclosure sampled along the longitudinal section observed under a polarized microscope after burnishing, polishing, and anodic coating.
Fig. 2 shows the microstructure photograph of the aluminum alloy sheet of Comparative Example 1 sampled along the longitudinal section observed under a polarized microscope after burnishing, polishing, and anodic coating.

Detailed Description

The 5 series aluminum alloy sheet and the manufacturing method thereof of the present disclosure will be further explained and interpreted below in conjunction with the specific examples of the description, but the explanation and interpretation do not constitute an undue limitation to the technical solution of the present disclosure.
The technical solution and technical effects of the present disclosure are illustrated with reference to the following Examples 1-6 and Comparative Examples 1-3.
The 5 series aluminum alloy sheets of Examples 1-6 and Comparative Examples 1-3 were prepared by the following steps, wherein the specific process parameters of each example and comparative example are listed in Table 2:

(1) aluminum alloy casting ingots were obtained by conventional melting-semi-continuous casting, wherein the chemical composition and the percentages thereof are listed in Table 1 below;
(2) hot rolling: the heating temperature was controlled at 500-540°C and held for 2-10h, and the initial rolling temperature of hot rough rolling was 500-540°C, the coiling temperature of hot rolling was 300-350°C;
(3) primary cold rolling: wherein the deformation rate was controlled at 30%-90%;
(4) intermediate annealing: wherein intermediate annealing was conducted by using a continuous annealing line or box furnace, so that the average grain size was 15µm-40µm after intermediate annealing; when the continuous annealing line was adopted for intermediate annealing, the annealing temperature of the continuous annealing line was 400-540°C with a holding time of 5s-60s; when the box furnace was adopted for intermediate annealing, the annealing temperature of the box furnace was 300-360°C with a holding time of 2-10h;
(5) secondary cold rolling: wherein the deformation rate was controlled to be 6%-20%.

In order to verify the influence of the manufacturing process parameters in each Example of the present disclosure on the implementation effect, the composition of 5 series aluminum alloy and the percentage thereof were adopted for Comparative Examples 1-3, but its manufacturing process parameters did not meet the present disclosure.

Table 1. (wt%, the balance is Fe and other unavoidable impurities)

	Si	Fe	Cu	Mn	Mg	Cr	Zn	Ti
Ex.1	0.09	0.5	0.05	0.29	2	0.4	0.01	0.05
Ex.2	0.15	0.37	0.2	0.18	2.94	0.08	0.02	0.02
Ex.3	0.07	0.25	0.15	0.09	2.35	0.17	0.03	0.01
Ex.4	0.09	0.19	0.11	0.5	2.95	0.01	0.02	0.04
Ex.5	0.12	0.2	0.06	0.03	3.5	0.5	0.03	0.02
Ex.6	0.08	0.15	0.04	0.01	4	0.16	0.05	0.03
CEx.1	0.1	0.2	0.06	0.03	2.4	0.4	0.02	0.01
CEx.2	0.09	0.2	0.06	0.03	2.4	0.4	0.02	0.03
CEx.3	0.09	0.2	0.06	0.03	3.5	0.4	0.01	0.02

Table 2 lists the specific manufacture process parameters for the 5-series aluminum alloy sheets of Examples 1-6 and the5-series aluminum alloy sheets of Comparative Examples 1-3.

Table 2.

	Heating temperature (°C) and holding time (h)	Initial rolling temperature of hot rough rolling (°C)	Coiling temperature of hot rolling (°C)	Slab thickness for hot rolling (mm)	Intermediate sheet thickness for cold rolling (mm)	Primary cold rolling deformation rate (%)	Intermediate annealing	Average grain size after intermediate annealing (µm)	Final product thickness /mm	Secondary cold rolling deformation rate /%	Total deformation rate of cold rolling	Final product annealing
Ex. 1	500°C× 10h	500	330	4.5	2.9	35.56	Continuous annealing line: temperature 540°C holding time 5s	40	2.7	6.9	-	-
Ex. 2	520°C× 4h	520	300	6	3.7	38.33	Continuous annealing line: temperature 410°C holding time 57s	28	3	18.9	-	-
Ex. 3	540°C× 2h	540	340	3	1.2	60.00	Box furnace: temperature 360°C holding time 2h	30	1	16.7	-	-
Ex. 4	520°C× 6h	520	330	4	2	50.00	Continuous annealing line: temperature 470°C holding time 10s	25	1.8	10.0	-	-
Ex. 5	510°C× 3h	510	340	3	0.85	71.67	Box furnace: temperature 300°C holding time 10h	20	0.7	17.6	-	-
Ex. 6	530°C× 7h	530	350	3	0.35	88.33	Box furnace: temperature 330°C holding time 6h	16	0.3	14.3	-	-
CE x.1	*480°C× 2h*	*480*	320	7	3.8	45.70	Box furnace: temperature 330°C holding time 3h	13	2.9	*23.7*	-	-
CE x.2	*490°C× 4h*	*490*	330	6	-	-	-	-	2.7	-	55	250°C ×4h
CE x.3	*480°C× 6h*	*480*	330	6	-	-	-	-	3	-	50	240°C ×3h

Note: Comparative Example 2 and 3 in the table did not involve the relevant data for primary cold rolling and secondary cold rolling due to the absence of an intermediate annealing step, but involved the total cold rolling deformation rate.

Fig. 1 shows the microstructure photograph of the 5 series aluminum alloy sheet of Example 1 of the present disclosure sampled along the longitudinal section observed under a polarized microscope after burnishing, polishing, and anodic coating.
As can be seen from Fig. 1, the average aspect ratio of the grain was 3, and there was no obvious shear band in the grain.
Fig. 2 shows the microstructure photograph of the 5 series aluminum alloy sheet of Comparative Example 1 sampled along the longitudinal section observed under a polarized microscope after burnishing, polishing, and anodic coating.
As can be seen from Fig. 2, the average aspect ratio of the grain was 10, and there were a large number of obvious shear bands in the grain.

In addition, with reference to the ASTM standard, the mechanical properties (tensile properties) along 0° direction of the aluminum alloy sheets of Examples and Comparative Examples produced by each preparation process were tested by tensile test with A50 gauge. With reference to GBT 232-2010, the 90-degree bending performance of the sample was tested with different bending radii at 90-degree, to obtain the minimal bending radius. The results of the tensile performance and bending performance are listed in Table 3.

Table 3.

	Tensile performance			Bending performance
	Rp0.2/MPa	Rm/MPa	A50/%	90° minimal bending radius/mm
Ex.1	139	211	16	0.45
Ex.2	180	235	10	0.5
Ex.3	170	219	11	0.3
Ex.4	185	232	13	0.4
Ex.5	192	245	10	0.2
Ex.6	209	265	12	0
CEx.1	205	244	8	*4.5*
CEx.2	165	224	15	*4.1*
CEx.3	170	235	14	6

As can be seen from Table 3, the 5 series aluminum alloy sheets of Example 1-6 of the present disclosure had a yield strength of 139-209MPa, a tensile strength of 211-265MPa and an elongation of ≥8%. In addition, they also had excellent bending performance. Among them, the sheet thicknesses of Examples 1-4 were ≥ 1mm, and it can be seen that they all met no cracking when the bending radius was ≤ 0.5mm at 90° bending.
In addition, Example 5 had a sheet thickness of 0.7mm and satisfied that there was no cracking at 90° bending when the bending radius was 0.5t; Example 6 had a sheet thickness of 0.3mm and satisfied that there was no cracking at 90° bending when the bending radius was 0t.
Different from the Examples of the present disclosure, the deformation rate of secondary cold rolling of Comparative Example 1 was too high, which resulted in too high degree of work hardening. The grain was significantly elongated and the intragranular dislocation density was significantly increased so that shear bands were formed, resulting in a significantly reduced bending performance of Comparative Example 1 compared with Example 1.
Comparative Example 2 and 3 adopted the conventional H22 preparation process, where an over-hardened cold-rolled coil was obtained by cold-rolling work hardening, and then the cold-rolled coil was incompletely annealed. The bending performance was also greatly reduced compared with the Examples.
It should be noted that combinations of the various technical features in this case are not limited to the combinations described in the claims of this case or the combinations described in the specific examples. All technical features recorded in this case can be combined freely or associated in any way unless a contradiction occurs.
It should also be noted that the examples listed above are only specific embodiments of the present disclosure. Obviously, the present disclosure is not limited to the above examples, and changes or modifications made thereto can be directly derived from the present disclosure or easily conceived of by those skilled in the art, all of which fall within the protection scope of the present disclosure.

Claims

A 5-series aluminum alloy sheet, wherein the 5-series aluminum alloy sheet has an average grain aspect ratio of 1-4, with no obvious shear bands within the grains.
The 5-series aluminum alloy sheet according to claim 1, wherein the 5-series aluminum alloy sheet further comprises each chemical element in mass percentage as follows: Si≤0.15%, Fe≤0.5%, Cu≤0.2%, Mn≤0.5%, Mg: 2.0~5.0% or 2.0~4.0%, Cr≤0.5%, Zn≤0.05%, Ti: 0.01~0.05%; or the mass percentages of the chemical elements of the 5-series aluminum alloy sheet are as follows: Si≤0.15%, Fe≤0.5%, Cu≤0.2%, Mn≤0.5%, Mg: 2.0~5.0% or 2.0~4.0%, Cr≤0.5%, Zn≤0.05%, Ti: 0.01~0.05%; with a balance of Al and unavoidable impurities.
The 5-series aluminum alloy sheet according to claim 1, wherein the mass percentages of the chemical elements of the 5-series aluminum alloy sheet are as follows: Si, 0.08~0.15%; Fe, 0.15~0.50%; Cu, 0.04~0.20%; Mn, 0.01~0.5%; Mg, 2.0~4.0%; Cr, 0.01~0.5%; Zn, 0.01~0.05%; Ti: 0.01~0.05%; with a balance of Al and unavoidable impurities.
The 5-series aluminum alloy sheet according to any one of claims 1-3, wherein the 5-series aluminum alloy sheet has a thickness of 0.2-3mm.
The 5-series aluminum alloy sheet according to any one of claims 1-4, wherein the 5-series aluminum alloy sheet has the following features: for the 5-series aluminum alloy sheet with a thickness t that meets 0.2≤t<0.5mm, when the bend radius is 0t, there is no cracking at 90° bending; for the 5 series aluminum alloy sheet with a thickness t that meets 0.5≤t<1mm, when the bend radius is 0.5t, there is no cracking at 90° bending; for the 5 series aluminum alloy sheet with a thickness of 1mm-3mm, when the bending radius is ≤0.5mm, there is no cracking at 90° bending, where t represents thickness.
The 5-series aluminum alloy sheet according to any one of claims 1-5, wherein the 5-series aluminum alloy sheet has a yield strength of 130-210MPa, a tensile strength of 210-270 MPa, and an elongation of ≥8%.
A manufacturing method for the 5-series aluminum alloy sheet, which comprises steps of:
(1) smelting and casting;

(2) hot rolling: wherein the heating temperature is controlled at 500-540°C and held for 2-10h, and the initial rolling temperature of hot rough rolling is 500-540°C;

(3) primary cold rolling;

(4) intermediate annealing, so that the average grain size is 15µm-40µm after intermediate annealing;

(5) secondary cold rolling: wherein the deformation rate is controlled to be 6%-20%.
The manufacturing method according to claim 7, wherein in step (2), the coiling temperature of hot rolling is controlled at 300-350°C.
The manufacturing method according to claim 7, wherein in step (3), the primary cold rolling deformation rate is controlled at 30%-90%.
The manufacturing method according to claim 7, wherein in step (4), a continuous annealing line is adopted for intermediate annealing, wherein the annealing temperature of the continuous annealing line was 400-540°C with a holding time of 5s-60s.
The manufacturing method according to claim 7, wherein in step (4), a box furnace is adopted for intermediate annealing, wherein the annealing temperature of the box furnace is 300-360°C with a holding time of 2-10h.
The manufacturing method according to claim 7, wherein there is no annealing step after step (5).
The manufacturing method according to claim 7, wherein the 5-series aluminum alloy sheet comprises Al and unavoidable impurities, wherein the 5-series aluminum alloy sheet also comprises each chemical element in mass percentage as follows: Si≤0.15%, Fe≤0.5%, Cu≤0.2%, Mn≤0.5%, Mg: 2.0~4.0%, Cr≤0.5%, Zn≤0.05%, Ti: 0.01~0.05%.
The manufacturing method according to claim 7, wherein the mass percentages of the chemical elements of the 5-series aluminum alloy sheet are as follows: Si≤0.15%, Fe≤0.5%, Cu≤0.2%, Mn≤0.5%, Mg: 2.0~4.0%, Cr≤0.5%, Zn≤0.05%, Ti: 0.01~0.05%; with a balance of Al and unavoidable impurities.
The manufacturing method according to claim 7, wherein the mass percentages of the chemical elements of the 5-series aluminum alloy sheet are as follows: Si, 0.08~0.15%; Fe, 0.15~0.50%; Cu, 0.04~0.20%; Mn, 0.01~0.5%; Mg, 2.0~4.0%; Cr, 0.01~0.5%; Zn, 0.01~0.05%; Ti: 0.01 ~0.05%; with a balance of Al and unavoidable impurities.
A 5-series aluminum alloy sheet which produced by the manufacturing method according to any one of claims 7-15.
The 5-series aluminum alloy sheet according to claim 16, wherein it has an average grain aspect ratio of 1-4, with no obvious shear bands within the grains.
The 5-series aluminum alloy sheet according to claim 16, wherein the thickness is 0.2-3mm.
The 5-series aluminum alloy sheet according to claim 16, wherein for the 5-series aluminum alloy sheet with a thickness t that meets 0.2≤t<0.5mm, when the bend radius is 0t, there is no cracking at 90° bending; for the 5 series aluminum alloy sheet with a thickness t that meets 0.5≤t<1mm, when the bend radius is 0.5t, there is no cracking at 90° bending; for the 5 series aluminum alloy sheet with a thickness of 1mm-3mm, when the bending radius is ≤0.5mm, there is no cracking at 90° bending, where t represents thickness.
The 5-series aluminum alloy sheet according to any one of claims 16-19, wherein it has a yield strength of 130-21OMPa, a tensile strength of 210-270 MPa, and an elongation of ≥8%.