A hot rolling method for aluminum alloy strip

Abstract

The embodiment of the present application provides a hot rolling method for an aluminum alloy strip, comprising: a hot rolling step: rolling a strip billet in multiple passes in sequence through multiple racks, and the final hot rolling temperature is 360°C to 400°C; a cooling step: cooling the aluminum alloy strip after hot rolling through a cooling device to reduce the temperature of the aluminum alloy strip to no more than 320°C; a coiling step: coiling the aluminum alloy strip after the cooling step. In the embodiment of the present application, the aluminum alloy strip after hot rolling is cooled by a cooling device to reduce its temperature to a temperature not exceeding 320°C to avoid subsequent interlayer adhesion, black wire and black spot problems, so that the final hot rolling temperature can be controlled at 360°C to 400°C during the hot rolling process, thereby increasing the recrystallization temperature of the grains and making the grain distribution of the aluminum alloy more uniform, which is beneficial to increasing the proportion of cubic texture of the aluminum alloy and improving the deep drawing property of the material.

Description

Technical Field

[0001] The present application relates to the technical field of metal hot rolling, and in particular to a hot rolling method for an aluminum alloy strip. Background Art

[0002] The hot-rolled aluminum alloy in the prior art is difficult to meet the deep drawing requirements of high-quality aluminum alloys such as can materials, high-voltage anode foils, and 6016 automobile plates. Summary of the invention

[0003] In view of this, an embodiment of the present application hopes to provide a hot rolling method for an aluminum alloy strip, so as to better control the microstructure and recrystallization of the aluminum alloy during the hot rolling process.

[0004] The present application provides a hot rolling method for an aluminum alloy strip, comprising:

[0005] Hot rolling step: the strip billet is rolled in multiple passes in sequence through multiple stands, wherein the final hot rolling temperature is 360°C to 400°C;

[0006] Cooling step: cooling the aluminum alloy strip after hot rolling by a cooling device to reduce the temperature of the aluminum alloy strip to no more than 320° C.

[0007] Coiling step: coiling the aluminum alloy strip after the cooling step.

[0008] In some embodiments, the hot rolling step has a rolling speed of 7 to 8 m / s.

[0009] In some embodiments, the distance between the cooling device and the hot rolling outlet of the end stand is 7 to 8 m.

[0010] In some embodiments, the time interval between the end of the hot rolling step and the cooling step is at least 1 second.

[0011] In some embodiments, the time interval between the end of the hot rolling step and the cooling step is at least 1 to 2 seconds.

[0012] In some embodiments, after the cooling step and before the coiling step, the hot rolling method further comprises:

[0013] The purging step is to purge the residual liquid on the surface of the aluminum alloy strip by using a purging device.

[0014] In some embodiments, the strip blank has a thickness of 38 to 42 mm, and the strip has a thickness of 1.8 to 2.5 mm after hot rolling.

[0015] In some embodiments, the total reduction in the hot rolling step is 4% to 6.5%.

[0016] In some embodiments, in each hot rolling pass of the hot rolling step, the reduction amount of a single pass increases successively from the beginning to the end.

[0017] In some embodiments, the reduction in each pass is 50% to 60%.

[0018] The hot rolling method of the aluminum alloy strip in the embodiment of the present application performs cooling treatment on the aluminum alloy strip after hot rolling by means of a cooling device to reduce its temperature to a temperature not exceeding 320°C, so as to avoid subsequent problems of interlayer adhesion, black wire and black spots. Therefore, during the hot rolling process, the final hot rolling temperature can be controlled at 360°C to 400°C, thereby increasing the recrystallization temperature of the grains and making the grain distribution of the aluminum alloy more uniform, which is beneficial to increasing the proportion of cubic texture of the aluminum alloy and improving the deep drawing performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a hot rolling production line according to an embodiment of the present application;

[0020] Figure 2 Schematic diagram of a hot rolling method for an aluminum alloy strip according to an embodiment of the present application.

[0021] Description of Reference Numerals

[0022] F1 / F2 / F3 / F4 / F5, frame; 10, aluminum alloy strip; 20, cooling device; 30, winding mechanism. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] The various specific technical features described in the specific embodiments can be combined in any suitable manner without contradiction, for example, different embodiments and technical solutions can be formed by combining different specific technical features. In order to avoid unnecessary repetition, various possible combinations of the specific technical features in the present invention will not be described separately.

[0025] In the following description, the terms "first\second\..." are only used to distinguish different objects, and do not mean that the objects have the same or related points. It should be understood that the directions "above", "below", "outside" and "inside" are all directions in normal use, and the directions "left" and "right" refer to the left and right directions shown in the specific corresponding schematic diagrams, which may be the left and right directions in normal use or not.

[0026] It should be noted that the terms "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element. "Multiple" means greater than or equal to two.

[0027] For some high-quality aluminum alloys, such as can materials, high-voltage anode foils, 6016 automotive plates and other high-quality aluminum alloys, the quality requirements for aluminum alloys are relatively high.

[0028] As for can body materials, they are aluminum alloy products used for deep drawing can making, which require good deep drawing performance. Otherwise, there will be problems such as deep drawing cracking, high ear making rate, can jamming and difficulty in thinning. However, the premise of deep drawing performance is that the texture of aluminum alloy materials must be well controlled.

[0029] When using 6016 aluminum alloy to produce automobile outer panels, a very difficult problem to solve is the ribbing defect on the surface during deep drawing, which seriously affects the appearance of the product.

[0030] The main means of controlling the ribbed grains is to make the grains small and uniform, which requires sufficient recrystallization during hot rolling, otherwise the grains will grow unevenly and the ribbed grains will appear.

[0031] Among them, 6016 aluminum alloy belongs to the 6xxx series, and its mass percentage composition is: silicon Si: 1.0~1.5, iron Fe: ≤0.50, copper Cu: ≤0.20, manganese Mn: ≤0.20, magnesium Mg: 0.25~0.6, chromium Cr: ≤0.10, zinc Zn: ≤0.20, titanium Ti: ≤0.15, unspecified other elements: each: ≤0.05. Total: ≤0.15, the balance is aluminum Al.

[0032] A hot rolling method for an aluminum alloy strip 10 is provided, wherein the hot rolling method is used to hot roll a strip-shaped blank after hot rough rolling, and the hot rolling can also be understood as hot finish rolling.

[0033] In the embodiment of the present application, the alloy composition of the aluminum alloy strip 10 is not limited, and the application scenario is not limited. In addition to being used for the above-mentioned can materials, high-voltage anode foils, 6016 automobile plates and other products, it can also be used in other products.

[0034] Here, hot rolling refers to rolling performed above the metal recrystallization temperature.

[0035] Before introducing the hot rolling method of the aluminum alloy strip according to the embodiment of the present application, the hot rolling production line according to the embodiment of the present application is briefly introduced.

[0036] See also Figure 1 The hot rolling production line includes multiple stands F1 / F2 / F3 / F4 / F5, a cooling device 20, and a winding mechanism 30.

[0037] A plurality of stands F1 / F2 / F3 / F4 / F5 are sequentially arranged along the moving direction of the aluminum alloy strip 10 , and each stand performs one pass rolling on the strip billet.

[0038] The winding mechanism is used to wind the aluminum alloy strip 10 after rolling.

[0039] The cooling device 20 is located between the end frame F5 and the winding mechanism 30 and is used to cool the aluminum alloy strip 10 after hot rolling. The cooling method is not limited, for example, spraying liquid on the surface of the aluminum alloy strip 10.

[0040] See also Figure 2 The hot rolling method of the aluminum alloy strip 10 according to the embodiment of the present application includes the following steps.

[0041] S1, hot rolling step: multiple passes of rolling are performed on the strip billet in sequence through multiple stands F1 / F2 / F3 / F4 / F5, wherein the final hot rolling temperature of the last pass is 360°C to 400°C. For example, 360°C, 370°C, 375°C, 380°C, 384°C, 387°C, 390°C, 393°C, 395°C, 398°C, 400°C, etc. The hot rolling temperature of each pass of the hot rolling step can be the same or different. The hot rolling temperature can be a dynamic temperature range.

[0042] In the embodiments of the present application, multiple times refers to no less than twice.

[0043] S2, cooling step: cooling the aluminum alloy strip 10 after hot rolling by the cooling device 20 to reduce the temperature of the aluminum alloy strip 10 to no more than 320° C. That is, the aluminum alloy strip 10 after the hot rolling step will be cooled by the cooling step.

[0044] S3, coiling step: coiling the aluminum alloy strip 10 after the cooling step.

[0045] It should be noted that when a metal undergoes plastic deformation, the grain orientation inside the metal becomes ordered to a certain extent. This preferred grain orientation directly produced in the deformed metal due to cold deformation becomes the deformation texture, and new crystallization cores are also obtained during the deformation process.

[0046] Metals with deformation texture undergo annealing and recrystallization, and new grains continue to grow until the original deformed structure disappears, and the properties of the metal or alloy also change significantly. This process is called recrystallization. The temperature at which the alloy material generates new grains is called the recrystallization temperature, and the temperature at which the microstructure is completely occupied by new grains is called the final recrystallization temperature. After recrystallization, the grains inside the metal material still have a preferred orientation, which becomes a recrystallization texture.

[0047] Texture directly affects the physical and mechanical properties of metal materials. Whether the presence of texture in metal materials is beneficial or harmful depends on the performance requirements of the material. For example, for aluminum alloy sheets that require deep drawing, cubic texture is beneficial to improve its deep drawing performance.

[0048] The inventors of the present application have discovered that in the related art, if the temperature of the aluminum alloy strip after the last hot rolling (i.e., final rolling) is too high, interlayer adhesion will occur, resulting in black silk and black lines on the surface of the coil, causing waste. Therefore, the final recrystallization temperature in the related art is around 320-340°C, which makes it difficult to achieve the crystallization effect of high-quality aluminum alloy, and it is also difficult to meet the high quality requirements of aluminum alloy.

[0049] The hot rolling method of the aluminum alloy strip 10 in the embodiment of the present application performs cooling treatment on the aluminum alloy strip 10 after hot rolling by means of a cooling device 20, so as to reduce its temperature to a temperature not exceeding 320°C, so as to avoid subsequent interlayer adhesion, black wire and black spot problems. Therefore, during the hot rolling process, the final hot rolling temperature can be controlled at 360°C to 400°C, thereby increasing the recrystallization temperature of the grains, making the grain distribution of the aluminum alloy more uniform, and being beneficial to increasing the proportion of cubic texture of the aluminum alloy, and improving the deep drawing property of the material.

[0050] Exemplarily, the rolling speed of the hot rolling step is 7 to 8 m / s (meters per second), for example, 7 m / s, 7.2 m / s, 7.3 m / s, 7.4 m / s, 7.5 m / s, 7.6 m / s, 7.7 m / s, 7.8 m / s, 7.9 m / s, 8 m / s, etc. In other words, the moving speed of the strip is 7 to 8 m / s. In this embodiment, by increasing the rolling speed, it is beneficial to increase the temperature of the deformation zone of the strip, thereby facilitating the increase of the final hot rolling end temperature.

[0051] Exemplarily, the time interval from the end of the hot rolling step to the cooling step is at least 1 second. That is, after the strip blank undergoes the last hot rolling, the cooling device 20 cools it down at least 1 second later, so that the aluminum alloy strip 10 has sufficient time to recrystallize at high temperature (the inventor has found that in the embodiment of the present application, when the recrystallization time is 1 second, the requirements of the recrystallization texture are met).

[0052] It can be understood that, taking the rolling speed of 7 to 8 m / s as an example, in this embodiment, the distance L between the cooling device 20 and the hot rolling outlet of the last-pass stand F1 / F2 / F3 / F4 / F5 is 7 to 8 m.

[0053] For example, the time interval between the end of the hot rolling step and the cooling step is at least 1 to 2 seconds. In this way, the efficiency of hot rolling can be taken into account while allowing the strip to have sufficient time to recrystallize at high temperature.

[0054] Exemplarily, after the cooling step and before the coiling step, the hot rolling method further includes: a purging step, in which the residual liquid on the surface of the aluminum alloy strip 10 is purged by a purging device. The residual liquid on the strip surface can be the coolant in the hot rolling process or the spray liquid sprayed in the cooling step. This is conducive to keeping the surface of the aluminum alloy strip 10 dry and clean, and reducing the probability of corrosion and impurities adhering to the surface of the aluminum alloy strip 10.

[0055] Exemplarily, the total reduction d of the hot rolling step is 4% to 6.5%. The total reduction d is the ratio of the thickness d1 of the strip after the last hot rolling to the thickness d0 of the strip before entering the hot rolling step, that is, d=d1 / d0. In this embodiment, the strip has a suitable total reduction.

[0056] Exemplarily, the thickness of the strip blank is 38 to 42 mm, for example, 38 mm, 38.5 mm, 39 mm, 39.4 mm, 40 mm, 40.6 mm, 41 mm, 42 mm, etc.; the thickness of the strip blank after hot rolling is 1.8 to 2.5 mm, for example, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, etc. The hot rough rolling step controls the thickness of the strip blank to 38 to 42 mm, so that the strip blank in the hot rolling step has a suitable initial thickness. The entire hot rolling step will roll the thickness of the strip blank from 38 to 42 mm to 1.8 to 2.5 mm.

[0057] The specific number of passes in the hot rolling step is not limited, for example, it can be three times or more, for example, three times, four times, five times, six times, etc.

[0058] It is understood that each rolling through a stand F1 / F2 / F3 / F4 / F5 can be referred to as a pass. The number of passes is consistent with the number of stands F1 / F2 / F3 / F4 / F5.

[0059] Exemplarily, in each hot rolling pass of the hot rolling step, the reduction amount of a single pass increases successively from the beginning to the end.

[0060] For example, in an embodiment where there are five passes in the hot rolling step, the reduction amount of the first pass < the reduction amount of the second pass < the reduction amount of the third pass < the reduction amount of the fourth pass < the reduction amount of the fifth pass. Among them, the fifth pass can be called the last pass.

[0061] In this embodiment, the reduction amount in a single pass is getting larger and larger, which is beneficial to increasing the reduction amount in the final pass, thereby facilitating controlling the final hot rolling temperature of the aluminum alloy strip 10 in the final pass at 360°C to 400°C.

[0062] Exemplarily, the reduction in the last pass is 50% to 60%, for example, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, etc. In this embodiment, the reduction is conducive to controlling the final hot rolling temperature of the aluminum alloy strip 10 in the last pass to 360° C. to 400° C.

[0063] For example, during the hot rolling process, the emulsion is sprayed onto the strip in each pass. Since the rolling end temperature needs to be increased, the flow rate and pressure of the sprayed emulsion can be reduced. For example, the spray pressure can be adjusted to 4 to 4.8 bar (bar, a unit of pressure, 1 bar = 0.1 MPa).

[0064] During the hot rolling process, the emulsion spraying mode was set to the Centre Buckle mode.

[0065] A specific embodiment of the present application is introduced below by taking 3104 grade aluminum alloy as an example.

[0066] The composition of 3104 aluminum alloy is as follows (mass percentage): silicon Si: ≤0.50%, iron Fe: ≤0.7%, copper Cu: ≤0.10%, manganese Mn: 0.9%~1.5%, magnesium Mg: ≤0.30%, chromium Cr: ≤0.10%, and the balance is aluminum and unavoidable impurities.

[0067] Table 1 shows the hot rolling process parameters of 3104 aluminum alloy

[0068]

[0069] The hot rolling parameters are shown in Table 1. The rolling process corresponding to the first pass is: rolling from 40 mm to 26.4 mm, and the reduction is 26.4 / 40=34%. The explanation of the parameters of the rolling process from the second to the fifth pass is the same as that of the first pass.

[0070] Table 2 shows the emulsion injection parameters of 3104 aluminum alloy in the hot rolling process.

[0071]

[0072] Among them, the existing flow rate level of the comparative example is level 1, and the corresponding injection pressure is 5-6 bar. The flow rate level in Table 2 is reduced to level 2. The flow rate level is related to the injection pressure. The smaller the injection pressure, the smaller the flow rate of the emulsion, and the heat taken away by the emulsion is relatively reduced, which is conducive to increasing the final hot rolling end temperature.

[0073] Table 3 is the process parameters of the comparative example

[0074]

[0075] Table 4 shows the process parameters of some embodiments of the present application.

[0076]

[0077] In Tables 3 and 4, the composition of the aluminum alloy with alloy grade 3104 refers to the composition of the above-mentioned 3104 aluminum alloy. F represents the free processing state, that is, after the last hot rolling, no annealing is performed. The final rolling temperature refers to the final temperature of the last hot rolling. In Tables 3 and 4, the direction refers to the direction during the mechanical property test, wherein 0° refers to the direction during the mechanical property test along the rolling direction, that is, the longitudinal direction (also the length direction) of the alloy strip, and 90° refers to the direction during the mechanical property test perpendicular to the rolling direction, that is, the transverse direction of the alloy strip.

[0078] In Table 3 and Table 4, samples D1 to D12 and samples Y1 to Y12 are samples produced from different batches of aluminum alloy billets with the same alloy composition.

[0079] It can be seen from Table 3 and Table 4 that in some embodiments of the present application, the tensile strength of the aluminum alloy after final rolling can be reduced, which is beneficial to improving the subsequent processing performance of the aluminum alloy, for example, having excellent deep drawing performance.

[0080] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present application, the schematic representation of the above terms is not necessarily for the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine different embodiments or examples described in the present application and the features of different embodiments or examples without contradiction.

[0081] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hot rolling method for an aluminum alloy strip, characterized in that: include: Hot rolling step: the strip billet is rolled in multiple passes in sequence through multiple stands, wherein the final hot rolling temperature is 380°C to 400°C, so as to increase the recrystallization temperature of the grains, make the grain distribution of the aluminum alloy more uniform, and help to increase the proportion of cubic texture of the aluminum alloy, wherein in each hot rolling pass of the hot rolling step, the reduction amount of a single pass increases in sequence from the beginning to the end, so as to help to increase the reduction amount of the final pass and control the final hot rolling temperature of the final pass; Wherein, the hot rolling step is hot finish rolling; Cooling step: cooling the aluminum alloy strip after hot rolling by a cooling device to reduce the temperature of the aluminum alloy strip to no more than 320° C. Coiling step: coiling the aluminum alloy strip after the cooling step; Wherein, the rolling speed of the hot rolling step is 7-8 m / s; The distance between the cooling device and the hot rolling outlet of the end frame is 7-8m; the time interval between the end of the hot rolling step and the cooling step is 1-2 seconds; The thickness of the strip blank is 38-42 mm, and the thickness of the strip blank after hot rolling is 1.8-2.5 mm; the total reduction in the hot rolling step is 4%-6.5%; and the reduction in the last pass is 50%-60%.

2. The hot rolling method of the aluminum alloy strip according to claim 1, characterized in that: After the cooling step and before the coiling step, the hot rolling method further comprises: The purging step is to purge the residual liquid on the surface of the aluminum alloy strip by using a purging device.

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