A method for preparing aluminum alloy plates in a short process

Abstract

The present invention discloses a short-process method for producing aluminum alloy sheet. The method involves cold rolling a hot-rolled aluminum alloy billet, which undergoes cold rolling from the first to the penultimate pass to obtain a cold-rolled intermediate plate. The intermediate plate is then subjected to a final cold rolling pass to obtain a cold-rolled sheet of target thickness. The cold-rolled sheet is then annealed online, coiled, and cooled to room temperature to obtain the aluminum alloy sheet. This method achieves the desired degree of recovery from the incomplete annealing (H2x) or stabilization annealing (H3x) state of the aluminum alloy through online annealing after the final cold rolling pass and utilizing coil auto-tempering. This significantly shortens the production process, reduces production costs, and improves the uniformity of microstructure and properties at the beginning, middle, and end of the coil.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy processing, and in particular relates to a method for preparing aluminum alloy plates through a short process. Background Art

[0002] Aluminum alloy sheet, due to its low density, excellent mechanical properties, formability, corrosion resistance, and lustrous appearance, is widely used in container panels, color-coated substrates, chassis and cabinets, umbrella ribs, and packaging. Series 1, 3, and 5 aluminum alloys are non-heat-treatable aluminum alloys, and work hardening is a key method for strengthening these alloys. To achieve the required work hardening level while maintaining good ductility, work hardening is typically achieved through cold rolling, where the deformation exceeds the required work hardening level. Incomplete annealing (H2x state) or stabilization annealing (H3x state) is then used to restore the material to a certain degree, reducing its strength and increasing its elongation. Conventional incomplete annealing and stabilization annealing processes for aluminum alloy sheet are typically performed in box-type annealing furnaces. Because box-type annealing furnaces heat the entire coil, the heating rate is slow and production efficiency is low. Furthermore, the cold-rolled coil undergoes a cooling process after leaving the cold rolling mill and then reheating in the box-type furnace, resulting in wasted residual heat and increased energy consumption. On the other hand, the time it takes for the outer and inner rings of the coil to reach the annealing temperature when heated in a box furnace causes large temperature fluctuations and large differences in the holding time of the entire coil, resulting in large fluctuations in the microstructure and properties of the coil head, middle, and tail.

[0003] Currently, aluminum alloy coils in the partially annealed and stabilized annealed states are primarily produced industrially in batches in box furnaces. Existing continuous annealing technology is primarily used in the production of 6- and 5-series automotive sheet metal panels. For example, application number 201510579121.0 discloses a continuous annealing furnace configured to anneal aluminum sheets at a set soaking temperature (TSET) of 450°C-590°C using a convection heat exchanger, thereby enabling the moving aluminum sheets to move substantially horizontally in a floating arrangement. This continuous annealing furnace still uses cooled cold-rolled coils as input, failing to fully utilize the residual heat of the cold-rolled coils. Chinese patent CN104775062B discloses an online solution (annealing) continuous annealing process. However, this process requires online quenching to achieve the solution (annealing) treatment, making it unsuitable for the production of partially annealed (H2x) and stabilized annealed (H3x) aluminum alloy sheets, which require a long hold period.

[0004] In view of this, it is urgent to study a preparation method suitable for the incomplete annealing (H2x) and stabilized annealing (H3x) states of 1 series, 3 series and 5 series aluminum alloy plates, which can not only improve energy utilization and reduce production costs, but also improve the uniformity of the structure and performance of the head, middle and tail of the coil. Summary of the Invention

[0005] In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide a method for preparing aluminum alloy plates in a short process, by online annealing after the final cold rolling and utilizing self-tempering of the coil to achieve the required degree of recovery of the aluminum alloy to the incomplete annealing (H2x) or stabilization annealing (H3x) state, thereby significantly shortening the production process, reducing production costs, and improving the uniformity of the microstructure and performance of the coil head, middle and tail.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing aluminum alloy plates in a short process, comprising: cold rolling an aluminum alloy hot-rolled billet, cold rolling the aluminum alloy hot-rolled billet through a first to a penultimate pass to obtain a cold-rolled intermediate plate, then cold rolling the cold-rolled intermediate plate through a final pass to obtain a cold-rolled plate of a target thickness, and then online annealing, coiling, and cooling the cold-rolled plate to room temperature to obtain an aluminum alloy coil.

[0008] Preferably, the preparation process of the aluminum alloy hot-rolled billet is as follows: after smelting according to the composition ratio of 1 series, 3 series or 5 series aluminum alloy, the aluminum alloy hot-rolled billet is obtained by semi-continuous casting and hot rolling.

[0009] Preferably, during the cold rolling process, intermediate annealing is performed between the first pass and the penultimate pass of the cold rolling process.

[0010] Preferably, the annealing temperature is 280-400° C., and the annealing time is 1-5 hours.

[0011] Preferably, during the cold rolling process, the final rolling temperature of the last cold rolling pass is 60-130°C.

[0012] Preferably, during the online annealing process, the cold-rolled sheet is heated online to 90-350° C. and kept warm for 2-5 seconds.

[0013] The present invention also provides an aluminum alloy sheet coil, which is prepared by the short-process method for preparing aluminum alloy sheets. The yield strength of the head, middle and tail of the aluminum alloy sheet coil is greater than 140 MPa, the tensile strength is greater than 161 MPa, and the elongation is greater than 4.9%.

[0014] The beneficial effects of the short-process method for preparing aluminum alloy plates provided by the present invention are as follows:

[0015] 1. The short-process method for preparing aluminum alloy sheets provided by the present invention fully utilizes the heat introduced during the plastic deformation of the final cold rolling pass, then raises the temperature to the required recovery temperature through online annealing, and then completes the recovery process through a slow cooling process of natural cooling, thereby achieving the microstructure and properties required by the H2x incomplete annealing state and H3x stabilized annealing state of 1 series, 3 series, and 5 series aluminum alloy sheets;

[0016] 2. Compared with the conventional cold rolling-cold rolled coil cooling-box furnace annealing process, the short-process method for preparing aluminum alloy sheets provided by the present invention eliminates the natural cooling of the cold rolled coil and the long heating and insulation process of the box furnace coil, thus significantly shortening the process flow.

[0017] 3. The short-process method for preparing aluminum alloy plates provided by the present invention directly performs online annealing on the single-layer cold-rolled plate after the final cold rolling, making the annealing temperature of the aluminum alloy more uniform, thereby ensuring the consistency of the structure and mechanical properties of the head, middle and tail of the entire coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0019] Figure 1 This is a schematic structural diagram of the final cold rolling-online annealing production line in the method for preparing aluminum alloy plates in the short process of the present invention. DETAILED DESCRIPTION

[0020] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below with reference to embodiments.

[0021] The present invention provides a short-process method for preparing aluminum alloy plates, which comprises cold rolling an aluminum alloy hot-rolled billet, cold rolling the aluminum alloy hot-rolled billet through a first to a penultimate pass to obtain a cold-rolled intermediate plate, then cold rolling the cold-rolled intermediate plate through a final pass to obtain a cold-rolled plate of a target thickness, and then annealing the cold-rolled plate online, coiling it, and cooling it to room temperature to obtain the aluminum alloy plate.

[0022] Combine Figure 1 As shown, the short-process method for preparing aluminum alloy plates of the present invention specifically includes the following steps:

[0023] (1) Preparation of aluminum alloy hot-rolled billets: Proportioning, smelting, and semi-continuous casting are performed according to the composition of 1 series, 3 series, or 5 series aluminum alloy to obtain alloy ingots, and the alloy ingots are hot-rolled to obtain aluminum alloy hot-rolled billets; with reference to GB / T 3190-2008 standard, typical 1 series, 3 series, and 5 series alloy grades and compositions are shown in Table 1;

[0024] Table 1 Typical 1 series, 3 series or 5 series aluminum alloy composition (wt%)

[0025] Si Fe Cu Mn Mg Cr Zn Ti 1050 aluminum alloy ≤0.25 ≤0.40 ≤0.05 ≤0.05 ≤0.05 - ≤0.05 ≤0.03 3003 aluminum alloy ≤0.6 ≤0.7 0.05-0.20 1.0-1.5 - - ≤0.10 - 3004 aluminum alloy ≤0.30 ≤0.7 ≤0.25 1.0-1.5 0.8-1.3 - ≤0.25 - 5052 aluminum alloy ≤0.25 ≤0.40 ≤0.10 ≤0.10 2.2-2.8 0.15-0.35 ≤0.10 -

[0026] (2) Cold rolling from the first pass to the penultimate pass: The aluminum alloy hot-rolled billet is cold rolled from the first pass to the penultimate pass according to a conventional method to obtain a cold-rolled intermediate plate; during the cold rolling process from the first pass to the penultimate pass, intermediate annealing can also be performed according to actual needs, wherein the annealing temperature is 280-400°C and the annealing time is 1-5 hours.

[0027] (3) Final cold rolling - online annealing: Place the cold rolled intermediate plate on Figure 1 On the left coiler 11 shown in the figure, the final cold rolling is carried out to obtain a cold-rolled plate of target thickness, wherein the final rolling temperature during the cold rolling process is 60-130°C; then, online annealing is carried out in the online heating furnace 16, and the cold-rolled plate is heated online to 90-350°C and kept warm for 2-5s.

[0028] (4) Coiling and cooling: The annealed cold-rolled sheet passes through the right turning roller 17 and is then coiled on the right coiler to obtain an aluminum alloy coil. The aluminum alloy coil is placed naturally so that the aluminum alloy is automatically tempered during the slow cooling process to achieve the desired recovery state of the aluminum alloy, that is, the H2x incomplete annealing state or the H3x stabilized annealing state.

[0029] In the above process, Figure 1 On the final cold rolling-online annealing production line shown, a left coiler 11, a left steering roller 12, a cold rolling mill (cold rolling mill working roller 13, cold rolling mill intermediate roller 14, cold rolling mill support roller 15), an online heating furnace 16, a right steering roller 17 and a right coiler 18 are sequentially arranged along the traveling direction X of the slab. The aluminum alloy is subjected to the final cold rolling and online annealing treatment through the final cold rolling-online annealing production line, making full use of the residual temperature on the surface of the cold-rolled plate and the self-tempering process of the aluminum alloy after heating to achieve the required recovery state of the aluminum alloy; the main reason is that the single-layer aluminum alloy plate is heated during the online annealing process, which not only ensures the temperature uniformity of the head, middle and tail of the aluminum alloy coil, but also greatly reduces the microstructure and performance fluctuations of the entire aluminum alloy coil.

[0030] The short-process method for preparing aluminum alloy plates of the present invention is further introduced below with reference to specific examples.

[0031] Example 1

[0032] In this embodiment, the alloy ingot 1 shown in Table 2 is used, and the alloy ingot 1 is hot-rolled into a 3.5 mm thick aluminum alloy hot-rolled billet according to a conventional hot rolling process, and then cold-rolled in two passes in a cold rolling mill to form a 0.95 mm thick cold-rolled intermediate plate, and then the 0.95 mm thick cold-rolled intermediate plate is rolled on a cold rolling mill. Figure 1The final rolling pass was performed on the cold rolling mill shown in FIG. to produce a 0.6 mm cold-rolled sheet, wherein the cold rolling finish temperature was 89° C. The cold-rolled sheet was then heated to 110° C. in an online heating furnace and held at that temperature for 5 seconds before being taken out of the online heating furnace for coiling. The aluminum alloy coil was then placed at room temperature for 24 hours and then cooled to room temperature to obtain an H36 aluminum alloy coil. The mechanical properties of the aluminum alloy coil at the head, middle, and tail in the 0° direction were tested by tensile tests using an A50 gauge length in accordance with ASTM standards. The results are shown in Table 3.

[0033] Example 2

[0034] In this embodiment, the alloy ingot 2 shown in Table 2 is used, and the alloy ingot 2 is hot-rolled into a 2.8 mm thick aluminum alloy hot-rolled billet according to a conventional hot rolling process, and then cold-rolled in two passes in a cold rolling mill into a 1.1 mm thick cold-rolled intermediate plate, and then the 1.1 mm thick cold-rolled intermediate plate is rolled on a cold rolling mill. Figure 1 The final rolling pass was performed on the cold rolling mill shown in FIG. 1 to produce a 0.7 mm cold-rolled sheet, wherein the cold rolling finish temperature was 95° C. The cold-rolled sheet was then heated online to 255° C. in an online heating furnace and held at 255° C. for 2 seconds before being coiled out of the online heating furnace. The aluminum alloy coil was then placed at room temperature for 72 hours and then cooled to room temperature to obtain an aluminum alloy coil. The mechanical properties of the aluminum alloy coil at the head, middle, and tail in the 0° direction were tested by tensile testing using an A50 gauge length in accordance with ASTM standards. The results are shown in Table 3.

[0035] Example 3

[0036] In the embodiment, the alloy ingot 3 as shown in Table 2 is used, and the alloy ingot 3 is hot-rolled into a 5 mm thick aluminum alloy hot-rolled billet according to a conventional hot rolling process, and then cold-rolled in two passes in a cold rolling mill to form a 1.6 mm thick cold-rolled intermediate plate, and then the 1.6 mm thick cold-rolled intermediate plate is rolled on a cold rolling mill. Figure 1 The final rolling pass was performed on the cold rolling mill shown in FIG. 1 to produce a 1.1 mm cold-rolled sheet, wherein the cold rolling finish temperature was 100° C. The cold-rolled sheet was then heated online to 275° C. in an online heating furnace and held at 275° C. for 3 seconds before being coiled out of the online heating furnace. The aluminum alloy coil was then placed at room temperature for 78 hours and then cooled to room temperature to obtain an aluminum alloy coil. The mechanical properties of the aluminum alloy coil at the head, middle, and tail in the 0° direction were tested by tensile testing using an A50 gauge length in accordance with ASTM standards. The results are shown in Table 3.

[0037] Example 4

[0038] In this embodiment, the alloy ingot 1 shown in Table 2 is used. The alloy ingot 1 is hot-rolled into a 5.5 mm thick aluminum alloy hot-rolled billet according to a conventional hot rolling process, and then cold-rolled into a 3 mm thick cold-rolled intermediate coil in two passes on a cold rolling mill. The 3 mm thick cold-rolled intermediate coil is then intermediate annealed at 330°C for 3 h in a box furnace, and then the 3 mm thick cold-rolled intermediate coil is cold-rolled into a 0.95 mm thick cold-rolled intermediate plate in two passes on a conventional cold rolling mill. The 0.95 mm thick cold-rolled intermediate plate is then cold-rolled into a 0.95 mm thick cold-rolled intermediate plate. Figure 1 The final rolling pass was performed on the cold rolling mill shown in FIG. to produce a 0.6 mm cold-rolled sheet, wherein the cold rolling finish temperature was 89° C. The cold-rolled sheet was then heated to 110° C. in an online heating furnace and held at that temperature for 5 seconds before being taken out of the online heating furnace for coiling. The aluminum alloy coil was then placed at room temperature for 24 hours and then cooled to room temperature to obtain an H36 aluminum alloy coil. The mechanical properties of the aluminum alloy coil at the head, middle, and tail in the 0° direction were tested by tensile tests using an A50 gauge length in accordance with ASTM standards. The results are shown in Table 3.

[0039] Comparative Example 1

[0040] In this comparative example, the alloy ingot 1 shown in Table 2 was used and hot-rolled into a 3.5 mm thick aluminum alloy hot-rolled billet according to a conventional hot rolling process. The billet was then cold-rolled in two passes on a cold rolling mill to form a 0.95 mm thick cold-rolled intermediate plate. The 0.95 mm thick cold-rolled intermediate plate was then Figure 1 The final rolling pass was carried out on the cold rolling mill shown in the figure to produce a 0.6 mm cold-rolled sheet, wherein the cold rolling finishing temperature was 85°C. The sheet was then heated to 110°C in a box furnace and kept at that temperature for 3 hours before being taken out of the furnace. After cooling to room temperature, the mechanical properties of the aluminum alloy coil in the 0° direction at the head, middle, and tail of the coil were tested by tensile tests using the A50 gauge length in accordance with the ASTM standard. The results are shown in Table 3.

[0041] Comparative Example 2

[0042] In this comparative example, the alloy ingot 2 shown in Table 2 was used and hot-rolled into a 2.8 mm thick aluminum alloy hot-rolled billet according to a conventional hot rolling process. The billet was then cold-rolled in two passes on a cold rolling mill to form a 1.1 mm thick cold-rolled intermediate plate. The 1.1 mm thick cold-rolled intermediate plate was then Figure 1 The final rolling pass was carried out on the cold rolling mill shown in the figure to produce a 0.7 mm cold-rolled sheet, wherein the cold rolling finishing temperature was 92°C. The sheet was then heated to 250°C in a box furnace and kept at that temperature for 3 h. The sheet was then cooled to 150°C in the furnace and then taken out of the furnace. After cooling to room temperature, the mechanical properties of the aluminum alloy coil in the 0° direction at the head, middle, and tail of the coil were tested by tensile tests using an A50 gauge length. The results are shown in Table 3.

[0043] Comparative Example 3

[0044] In this comparative example, the alloy ingot 3 shown in Table 2 was used and hot-rolled into a 5 mm thick aluminum alloy hot-rolled billet according to a conventional hot rolling process. The billet was then cold-rolled in two passes on a cold rolling mill to form a 1.6 mm thick cold-rolled intermediate plate. The 1.6 mm thick cold-rolled intermediate plate was then Figure 1 The final rolling pass was carried out on the cold rolling mill shown in the figure to produce a 1.1 mm cold-rolled sheet, wherein the cold rolling finishing temperature was 100°C. The sheet was then heated to 250°C in a box furnace and kept at that temperature for 3 h. The sheet was then cooled to 150°C in the furnace and then taken out of the furnace. After cooling to room temperature, the mechanical properties of the aluminum alloy coil in the 0° direction at the head, middle, and tail of the coil were tested by tensile tests using an A50 gauge length. The results are shown in Table 3.

[0045] Table 2 Chemical composition of alloys of Examples and Comparative Examples (wt%)

[0046] Si Fe Cu Mn Mg Cr Zn Ti Al Alloy ingot 1 0.13 0.26 0.03 0.06 2.65 0.19 0.004 0.014 margin Alloy ingot 2 0.10 0.32 0.096 1.0 1.2 <0.05 0.009 0.016 margin Alloy ingot 3 0.17 0.55 0.10 1.0 <0.05 <0.05 0.008 0.022 margin

[0047] Table 3 Mechanical properties of the aluminum alloy coil head, middle and tail at 0° in the examples and comparative examples

[0048]

[0049]

[0050] As shown in Table 3, compared with Comparative Examples 1-3, the yield strength (YS), tensile strength (TS), and elongation (EL) of the head, middle, and tail of the aluminum alloy coil in the embodiment of the present invention have less fluctuation, and the consistency of mechanical properties is better than the mechanical properties of the plates produced by conventional box furnace annealing in Comparative Examples 1-3.

[0051] In summary, the short-process method for preparing aluminum alloy plates provided by the present invention fully utilizes the heat introduced during the plastic deformation of the final cold rolling pass, and then raises the temperature to the required recovery temperature through online annealing, and then completes the recovery process through a slow cooling process of natural cooling, thereby achieving the microstructure and properties required for the H2x incomplete annealing state and H3x stabilized annealing state of 1 series, 3 series and 5 series aluminum alloy plates; compared with the conventional cold rolling-cold rolled coil cooling-box furnace annealing process, the short-process method for preparing aluminum alloy plates of the present invention omits the natural cooling of the cold rolled coil and the long-term heating and insulation process of the box furnace coil, thereby greatly shortening the process flow; the short-process method for preparing aluminum alloy plates provided by the present invention directly performs online annealing on the single-layer cold rolled plate after the final cold rolling pass, so that the annealing temperature of the prepared aluminum alloy is uniform, thereby ensuring the consistency of the structure and performance of the head, middle and tail of the entire coil.

[0052] Those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present invention and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A short-process preparation method suitable for 1 series, 3 series or 5 series aluminum alloy plates in H2x incomplete annealing state or H3x stabilized annealing state, characterized in that: The aluminum alloy hot-rolled billet is cold rolled, and the aluminum alloy hot-rolled billet is cold rolled from the first pass to the second to the last pass to obtain a cold-rolled intermediate plate, and the cold-rolled intermediate plate is cold rolled in the final pass to obtain a cold-rolled plate of target thickness, and the cold-rolled plate is annealed online, coiled, and cooled to room temperature to obtain an aluminum alloy sheet coil. The preparation process of the aluminum alloy hot-rolled billet is as follows: after smelting according to the composition ratio of 1 series, 3 series or 5 series aluminum alloy, the aluminum alloy hot-rolled billet is obtained by semi-continuous casting and hot rolling. During the cold rolling process, the final cold rolling temperature is 60-130°C. During the coiling and cooling process, the annealed cold-rolled sheet passes through the right turning roller and is then coiled on the right coiler to obtain an aluminum alloy coil. The aluminum alloy coil is left to stand naturally so that the aluminum alloy is automatically tempered during the slow cooling process to achieve the desired recovery state of the aluminum alloy, i.e., the H2x incomplete annealing state or the H3x stabilized annealing state. The aluminum alloy plate coil prepared by the short-process method for preparing aluminum alloy plates has a yield strength greater than 140 MPa at the head, middle and tail, a tensile strength greater than 161 MPa, and an elongation greater than 4.9%.

2. The short-process preparation method for 1 series, 3 series or 5 series aluminum alloy plates in H2x incomplete annealing state or H3x stabilized annealing state according to claim 1, characterized in that: During the cold rolling process, intermediate annealing is performed between the first pass and the penultimate pass of the cold rolling process.

3. The short-process preparation method for 1 series, 3 series or 5 series aluminum alloy plates in H2x incomplete annealing state or H3x stabilized annealing state according to claim 2, characterized in that: The annealing temperature of the intermediate annealing is 280-400° C., and the annealing time is 1-5 hours.

4. The short-process preparation method for 1 series, 3 series or 5 series aluminum alloy plates in H2x incomplete annealing state or H3x stabilized annealing state according to claim 1, characterized in that: During the online annealing process, the cold-rolled sheet is heated online to 90-350° C. and kept at this temperature for 2-5 seconds.

5. An aluminum alloy sheet coil, characterized in that: The aluminum alloy sheet coil is prepared by the short-process preparation method applicable to the H2x incomplete annealing state or H3x stabilized annealing state of 1 series, 3 series or 5 series aluminum alloy sheets as described in one of claims 1-4. The yield strength of the head, middle and tail of the aluminum alloy sheet coil is greater than 140 MPa, the tensile strength is greater than 161 MPa, and the elongation is greater than 4.9%.

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