5-series aluminum alloy strip for vehicle-mounted backlight plate and preparation method of 5-series aluminum alloy strip

Abstract

The invention relates to a 5-series aluminum alloy strip for a vehicle-mounted backlight plate and a preparation method of the 5-series aluminum alloy strip, and belongs to the technical field of aluminum alloy processing and manufacturing. The aluminum alloy comprises the following components in percentage by mass: less than or equal to 0.12% of Si, 0.2-0.3% of Fe, 0.07-0.09% of Cu, 0.35-0.45% of Mn, 5.05-5.15% of Mg and the balance of Al. Cr: 0.02 to 0.04%; less than or equal to 0.03% of Zn; the content of a single impurity is less than or equal to 0.03%, the total content of the impurities is less than or equal to 0.15%, and the balance is Al. The preparation method comprises the steps of burdening, smelting, refining, casting, saw cutting, surface milling, soaking, hot rolling, cold rolling, pulling, straightening, cleaning and straightening, intermediate annealing, cold rolling, pulling, straightening, cleaning and straightening, stabilizing annealing, pulling, straightening and straightening, finished product pouring and packaging. Through component adjustment, hot rolling optimization, annealing, stabilization, stretch straightening and the like, the product performance meets the strength and plasticity requirements, and the production cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy processing and manufacturing, and specifically relates to a 5 series aluminum alloy strip for a vehicle-mounted backlight panel and a preparation method thereof. Background Art

[0002] In the early days, LCD backlight panels for electronic products such as car tablets and mobile phones mainly used high-strength steel. However, as electronic products develop in the direction of thinness, lightness, easy heat conduction, and functional integration, the shortcomings of steel have gradually become apparent, and the advantages of aluminum alloys have continued to be reflected.

[0003] The use of LCD backlight panels for electronic products such as car tablets and mobile phones requires that high-strength performance be guaranteed while also ensuring that there is no cracking during bending and forming, so that they meet a certain plasticity. However, as the strength of the aluminum alloy increases, the plasticity will decrease, and as the plasticity of the aluminum alloy increases, its strength will decrease. Summary of the invention

[0004] In view of this, the present invention discloses a 5 series aluminum alloy strip for a vehicle backlight panel and a preparation method thereof, so that it can simultaneously meet high strength and high plasticity. The specific scheme is as follows:

[0005] A 5-series aluminum alloy strip for a vehicle backlight panel, wherein the vehicle-use 5-series aluminum alloy comprises, in terms of mass percentage, Si: ≤0.12%, Fe: 0.2-0.3%, Cu: 0.07-0.09%, Mn: 0.35-0.45%, Mg: 5.05-5.15%, Cr: 0.02-0.04%, Zn≤0.03%, Ti: 0.01-0.025%, a single impurity ≤0.03%, a total impurity ≤0.15%, and the balance is Al.

[0006] The present invention also discloses a method for preparing a 5 series aluminum alloy strip for a vehicle-mounted backlight panel, comprising the following steps:

[0007] A. After the aluminum alloy is proportioned according to mass percentage, it is melted and refined in a furnace, and the aluminum liquid is cast into an aluminum alloy ingot;

[0008] B. After the aluminum alloy ingot is cooled, the head and tail are cut off, and the solidified shell layer on the surface of the ingot is removed by milling;

[0009] C. Place the sawn and milled ingot in a pusher heating furnace for uniform heating, with the metal temperature at 480°C to 530°C for 2 to 5 hours;

[0010] D. Take the ingot out of the furnace and hot-roll it, control the final rolling temperature of hot rolling to 310℃~335℃, and the thickness of hot-rolled coil is 2.2mm~2.8mm;

[0011] E. Force the coil to cool to room temperature and then cold roll it;

[0012] F. After cold rolling, it is cleaned, stretched and straightened once, and then coiled and put into a box-type annealing furnace for annealing. During the annealing process, a protective atmosphere is used, and the oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305°C, it is kept warm for 4 hours to achieve a completely O-state structure, and then cooled to room temperature after intermediate annealing;

[0013] G. Cold rolling the coil to the finished thickness;

[0014] H. After cold rolling, it is cleaned, and after coiling, it is put into a box-type annealing furnace for stabilization treatment, and then cooled to room temperature after stabilization; after cold rolling, it is cleaned, stretched and straightened for the second time, and after coiling, it is put into a box-type annealing furnace for stabilization treatment, and then cooled to room temperature after stabilization;

[0015] I. Cut and package the 5 series aluminum alloy strip prepared in step H.

[0016] As a supplement to the technical solution of the present invention, in the step E, the cold rolling is performed to the intermediate thickness, and the cold rolling processing rate from the intermediate thickness to the finished product thickness is reserved at 50% to 60%.

[0017] As a supplement to the technical solution of the present invention, the center retreat thickness is 0.40 mm to 0.75 mm.

[0018] As a supplement to the technical solution of the present invention, the stabilization treatment system in step H is to keep the core of the coil warm for 4 hours when the temperature reaches 150-200°C.

[0019] As a supplement to the technical solution of the present invention, in the step H, the strip after stabilization treatment is stretched and straightened three times.

[0020] As a supplement to the technical solution of the present invention, in the step H, the secondary stretching straightening stretching rate is 0.4% to 0.6%.

[0021] As a supplement to the technical solution of the present invention, in the step H, the stretching rate of the three-stretching straightening is 0.3% to 0.5%.

[0022] As a supplement to the technical solution of the present invention, in the step F, the stretching rate of the primary stretching straightening is 0.3% to 0.5%.

[0023] Beneficial effect: The 5 series aluminum alloy strip for vehicle backlight panel disclosed in the present invention and its preparation method optimize the alloy composition and the hot rolling, annealing, stabilization, stretching and straightening steps in the preparation method. The prepared aluminum alloy strip has a tensile strength of more than 350 MPa, a yield strength of more than 280 MPa, an elongation after fracture of more than 9.5%, and does not break when bent 180°. DETAILED DESCRIPTION

[0024] A 5 series aluminum alloy strip for a vehicle backlight panel and a preparation method thereof are used to provide an aluminum product that can ensure high strength and can be bent (180 degree 0t bending, i.e. 180 degree bending, r angle is 0) without cracking to replace steel.

[0025] The specific production steps are as follows:

[0026] A. Melting, furnace refining, online degassing, online filtering are carried out according to the following aluminum alloy mass percentage, and then casting into aluminum alloy ingots.

[0027] Si: ≤0.12%, Fe: 0.2~0.3%, Cu: 0.07~0.09%, Mn: 0.35~0.45%, Mg: 5.05~5.15%; Cr: 0.02~0.04%; Zn≤0.03%; Ti: 0.01~0.025%, single impurity ≤0.03%, total impurities ≤0.15%, the balance is Al.

[0028] The specific smelting process is as follows: the ingredients are put into the smelting furnace in turn for smelting, and flux is used for refining and covering. After the materials in the furnace are melted, stirring begins. After refining and slagging, after obtaining qualified chemical composition, Ar gas and Cl2 mixed gas are used to bring hydrogen and fine impurities in the aluminum liquid to the surface of the melt, thereby reducing the gas content of the melt.

[0029] Furthermore, in step A, double-stage filtration is used during the casting process, including but not limited to: plate CFF filtration + plate CFF filtration, plate CFF filtration + deep bed filtration, plate CFF filtration + tubular filtration, thereby reducing the slag content of the melt, ensuring the purity of the melt, and avoiding black threads and black lines in the material structure caused by impure melt, thereby ensuring the surface quality. Al-5Ti-B is used for online refinement treatment to ensure the grain size of the aluminum alloy ingot.

[0030] B. After the aluminum alloy ingot is cooled, the head and tail are cut off, and the solidified shell layer on the surface of the ingot is removed by milling;

[0031] C. Place the sawn and milled ingot in a pusher heating furnace for uniform heating, with the metal temperature at 480°C to 530°C for 2 to 5 hours;

[0032] D. Take the ingot out of the furnace and hot-roll it, control the final rolling temperature of hot rolling to 310℃~335℃, and the thickness of hot-rolled coil is 2.2mm~2.8mm;

[0033] E. Force the coil to cool, and after cooling to room temperature, cold roll it to the middle thickness, where the middle thickness is 50% to 60% of the cold rolling processing rate to the finished product thickness;

[0034] F. After cold rolling, it is cleaned and stretched and straightened once. The stretching rate of the stretching and straightening is 0.3% to 0.5%. Then, it is coiled and put into a box-type annealing furnace for annealing. During the annealing process, a protective atmosphere is used. The oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305°C, it is kept warm for 4 hours to achieve a completely O-state structure. After intermediate annealing, it is cooled to room temperature;

[0035] G. Cold rolling the coil to the finished thickness;

[0036] H. After cold rolling, the coil is cleaned and stretched twice, and the stretching rate of the stretching is 0.4% to 0.6%. Then, the coil is coiled and put into a box-type annealing furnace for stabilization treatment. The stabilization treatment system is that when the core of the coil reaches 150℃ to 200℃, it is kept warm for 4 hours, then cooled to room temperature, and stretched three times, and the stretching rate of the stretching is 0.3% to 0.5%;

[0037] I. Cut and package the 5 series aluminum alloy strip prepared in step H.

[0038] As a supplement to the above technical solution, the alloy state of the 5 series aluminum alloy strip is 5 series-H38, and its thickness is 0.2mm to 0.3mm.

[0039] In the above technical solution, when selecting the alloy components, the alloy components are optimized, and Mg is used as the main alloy element. By increasing the Mg content in the melt and limiting the Mn and Cu contents within a very small range, the prepared aluminum alloy strip can have a higher strength and extremely stable mechanical properties. While the strength is improved, the plasticity will decrease. In this regard, the plasticity will be improved by reducing the post-processing rate to 50% to 60%, adjusting the stabilization annealing temperature to 150°C to 200°C, and extending the annealing time to 4 hours.

[0040] On the basis of the above-mentioned alloy composition optimization, by reducing the thickness of the hot-rolled coil, the thickness of the hot-rolled coil using the traditional process is 5.5 mm, while the present application reduces it to 2.5 mm, reducing two cold rolling passes and one intermediate annealing, reducing the production process, and saving energy consumption while meeting its performance indicators.

[0041] By optimizing the reserved processing rate after annealing and increasing the stabilization annealing system, it is beneficial to obtain high-strength aluminum alloy materials with a tensile strength of more than 350MPa and no cracking under 180°0t bending. Too high a reserved processing rate and a short stabilization time will lead to insufficient plasticity.

[0042] At the same time, by adopting three stretching and straightening, the coil and longitudinal stripping plate shape is qualified, the cut small plate and punching plate surface is not deformed, and the plate shape characteristic use requirements are met; the second stretching and bending straightening (stretching rate is 0.4-0.6%) preliminarily removes the internal stress and reduces the transverse bending; the third stretching and bending straightening (stretching rate is 0.3-0.5%) further removes the internal stress and flattens the transverse bending. The internal stress is mainly caused by the uneven longitudinal rolling deformation of the strip during the rolling process, including the finished product rolling process. If the post-process straightening and internal stress removal treatment is not performed, the subsequent longitudinal stripping and cutting of small plates by customers will be warped and unqualified.

[0043] Embodiment 1:

[0044] A. Melting, furnace refining, online degassing, online filtering are carried out according to the following aluminum alloy mass percentage, and then casting into aluminum alloy ingots.

[0045] Si: 0.071%, Fe: 0.225%, Cu: 0.081%, Mn: 0.385%, Mg: 5.105%, Cr: 0.027%, Zn: 0.018%, Ti: 0.019%, single impurity ≤ 0.03%, total impurities ≤ 0.15%, the balance is Al.

[0046] The specific smelting process is as follows: the ingredients are put into the smelting furnace in turn for smelting, and flux is used for refining and covering. After the materials in the furnace are melted, stirring begins. After refining and slagging, after obtaining qualified chemical composition, Ar gas and Cl2 mixed gas are used to bring hydrogen and fine impurities in the aluminum liquid to the surface of the melt, thereby reducing the gas content of the melt.

[0047] Furthermore, in step A, double-stage filtration is used during the casting process, including but not limited to: plate CFF filtration + plate CFF filtration, plate CFF filtration + deep bed filtration, plate CFF filtration + tubular filtration, thereby reducing the slag content of the melt, ensuring the purity of the melt, and avoiding black threads and black lines in the material structure caused by impure melt, thereby ensuring the surface quality. Al-5Ti-B is used for online refinement treatment to ensure the grain size of the aluminum alloy ingot.

[0048] B. After the aluminum alloy ingot is cooled, the head and tail are cut off, and the solidified shell layer on the surface of the ingot is removed by milling;

[0049] C. Place the sawn and milled ingot in a pusher heating furnace for uniform heating. The metal temperature is 490°C and the temperature is kept for 3.5 hours.

[0050] D. Take the ingot out of the furnace and hot roll it, control the final rolling temperature of hot rolling to 325℃, and the thickness of hot rolled coil is 2.5mm;

[0051] E. Force the coil to cool to room temperature and then cold roll it to a 0.53mm thickness;

[0052] F. After cold rolling, it is cleaned and stretched and straightened. The stretching rate of the stretching and straightening is 0.4%. Then, it is coiled and put into the box annealing furnace for annealing. During the annealing process, the protective atmosphere is treated and the oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305℃, it is kept warm for 4 hours to achieve a completely O-state structure. After intermediate annealing, it is cooled to room temperature;

[0053] G. Cold rolling the coil to a finished product thickness of 0.25 mm;

[0054] H. After cold rolling, the coil is cleaned and stretched and straightened once. The stretching rate of the stretching and straightening is 0.5%. Then, it is coiled and sent to a box-type annealing furnace for stabilization treatment. The stabilization treatment system is that when the core of the coil reaches 180°C, it is kept warm for 4 hours, then cooled to room temperature, and then stretched and straightened twice. The stretching rate of the stretching and straightening is 0.4%.

[0055] I. Cut and package the 5 series aluminum alloy strip prepared in step H.

[0056] Embodiment 2:

[0057] A. Melting, furnace refining, online degassing, online filtering are carried out according to the following aluminum alloy mass percentage, and then casting into aluminum alloy ingots.

[0058] Si: 0.068%, Fe: 0.235%, Cu: 0.087%, Mn: 0.381%, Mg: 5.102%, Cr: 0.025%, Zn: 0.015%, Ti: 0.017%, single impurity ≤ 0.03%, total impurities ≤ 0.15%, the balance is Al.

[0059] The specific smelting process is as follows: the ingredients are put into the smelting furnace in turn for smelting, and flux is used for refining and covering. After the materials in the furnace are melted, stirring begins. After refining and slagging, after obtaining qualified chemical composition, Ar gas and Cl2 mixed gas are used to bring hydrogen and fine impurities in the aluminum liquid to the surface of the melt, thereby reducing the gas content of the melt.

[0060] Furthermore, in step A, double-stage filtration is used during the casting process, including but not limited to: plate CFF filtration + plate CFF filtration, plate CFF filtration + deep bed filtration, plate CFF filtration + tubular filtration, thereby reducing the slag content of the melt, ensuring the purity of the melt, and avoiding black threads and black lines in the material structure caused by impure melt, thereby ensuring the surface quality. Al-5Ti-B is used for online refinement treatment to ensure the grain size of the aluminum alloy ingot.

[0061] B. After the aluminum alloy ingot is cooled, the head and tail are cut off, and the solidified shell layer on the surface of the ingot is removed by milling;

[0062] C. Place the sawn and milled ingot in a pusher heating furnace for uniform heating, with the metal temperature at 500°C for 3 hours;

[0063] D. Take the ingot out of the furnace and hot roll it, control the final rolling temperature of hot rolling to 320°C, and the thickness of hot rolled coil is 2.4mm;

[0064] E. Force the coil to cool to room temperature and then cold roll it to a 0.56 mm thickness;

[0065] F. After cold rolling, it is cleaned and stretched and straightened. The stretching rate of the stretching and straightening is 4.5%. Then, it is coiled and put into the box annealing furnace for annealing. During the annealing process, the protective atmosphere is treated and the oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305℃, it is kept warm for 4 hours to achieve a completely O-state structure. After intermediate annealing, it is cooled to room temperature;

[0066] G. Cold rolling the coil to a finished product thickness of 0.25 mm;

[0067] H. After cold rolling, the coil is cleaned and stretched and straightened for the second time. The stretching rate of the stretching and straightening is 0.45%. Then, the coil is coiled and sent to a box-type annealing furnace for stabilization treatment. The stabilization treatment system is that when the core of the coil reaches 175°C, it is kept warm for 4 hours and then cooled to room temperature. Then, the coil is stretched and straightened for the second time. The stretching rate of the stretching and straightening is 0.35%.

[0068] I. Cut and package the 5 series aluminum alloy strip prepared in step H.

[0069] Embodiment 3:

[0070] A. Melting, furnace refining, online degassing, online filtering are carried out according to the following aluminum alloy mass percentage, and then casting into aluminum alloy ingots.

[0071] Si: 0.074%, Fe: 0.215%, Cu: 0.088%, Mn: 0.391%, Mg: 5.095%, Cr: 0.032%, Zn: 0.016%, Ti: 0.020%, single impurity ≤ 0.03%, total impurities ≤ 0.15%, the balance is Al.

[0072] The specific smelting process is as follows: the ingredients are put into the smelting furnace in turn for smelting, and flux is used for refining and covering. After the materials in the furnace are melted, stirring begins. After refining and slagging, after obtaining qualified chemical composition, Ar gas and Cl2 mixed gas are used to bring hydrogen and fine impurities in the aluminum liquid to the surface of the melt, thereby reducing the gas content of the melt.

[0073] Furthermore, in step A, double-stage filtration is used during the casting process, including but not limited to: plate CFF filtration + plate CFF filtration, plate CFF filtration + deep bed filtration, plate CFF filtration + tubular filtration, thereby reducing the slag content of the melt, ensuring the purity of the melt, and avoiding black threads and black lines in the material structure caused by impure melt, thereby ensuring the surface quality. Al-5Ti-B is used for online refinement treatment to ensure the grain size of the aluminum alloy ingot.

[0074] B. After the aluminum alloy ingot is cooled, the head and tail are cut off, and the solidified shell layer on the surface of the ingot is removed by milling;

[0075] C. Place the sawn and milled ingot in a pusher heating furnace for uniform heating, with the metal temperature at 510°C for 3.5 hours;

[0076] D. Take the ingot out of the furnace and hot roll it, control the final rolling temperature of hot rolling to 330°C, and the thickness of hot rolled coil is 2.6mm;

[0077] E. Force the coil to cool to room temperature and then cold roll it to a mid-roll thickness of 0.58 mm;

[0078] F. After cold rolling, it is cleaned and stretched and straightened. The stretching rate of the stretching and straightening is 0.5%. Then, after coiling, it enters the box-type annealing furnace for annealing. During the annealing process, a protective atmosphere is used. The oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305°C, it is kept warm for 4 hours to achieve a completely O-state structure. After intermediate annealing, it is cooled to room temperature;

[0079] G. Cold rolling the coil to a finished product thickness of 0.25 mm;

[0080] H. After cold rolling, the steel sheet is cleaned and stretched and straightened for the second time. The stretching rate of the stretching and straightening is 0.55%. Then, the steel sheet is coiled and sent to a box-type annealing furnace for stabilization treatment. The stabilization treatment system is that when the core of the steel sheet reaches 185°C, it is kept warm for 4 hours, then cooled to room temperature, and then stretched and straightened for the second time. The stretching rate of the stretching and straightening is 0.45%.

[0081] I. Cut and package the 5 series aluminum alloy strip prepared in step H.

[0082] Comparative Example 1: Conventional 5182 aluminum alloy strip production process

[0083] A. Melting, furnace refining, online degassing, online filtering are carried out according to the following aluminum alloy mass percentage, and then casting into aluminum alloy ingots.

[0084] Si: 0.078%, Fe: 0.233%, Cu: 0.03%, Mn: 0.312%, Mg: 4.52%, Cr: 0.032%, Zn: 0.018%, Ti: 0.025%, single impurity ≤ 0.05%, total impurities ≤ 0.15%, the balance is Al.

[0085] The specific smelting process is as follows: the ingredients are put into the smelting furnace in turn for smelting, and flux is used for refining and covering. After the materials in the furnace are melted, stirring begins. After refining and slagging, after obtaining qualified chemical composition, Ar gas and Cl2 mixed gas are used to bring hydrogen and fine impurities in the aluminum liquid to the surface of the melt, thereby reducing the gas content of the melt.

[0086] Furthermore, in step A, double-stage filtration is used during the casting process, including but not limited to: plate CFF filtration + plate CFF filtration, plate CFF filtration + deep bed filtration, plate CFF filtration + tubular filtration, thereby reducing the slag content of the melt, ensuring the purity of the melt, and avoiding black threads and black lines in the material structure caused by impure melt, thereby ensuring the surface quality. Al-5Ti-B is used for online refinement treatment to ensure the grain size of the aluminum alloy ingot.

[0087] B. After the aluminum alloy ingot is cooled, the head and tail are cut off, and the solidified shell layer on the surface of the ingot is removed by milling;

[0088] C. Place the sawn and milled ingot in a pusher heating furnace for uniform heating. The metal temperature is 480°C and kept warm for 3 hours.

[0089] D. Take the ingot out of the furnace and hot roll it, control the final rolling temperature of hot rolling to 325℃, and the thickness of hot rolled coil is 5.5mm;

[0090] E. Force the coil to cool to room temperature and then cold-roll it to a first intermediate thickness of 2.0 mm;

[0091] F. After cold rolling, it is cleaned, and then coiled and put into the box annealing furnace for annealing. During the annealing process, the protective atmosphere is treated, and the oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305℃, it is kept warm for 4 hours to achieve a completely O-state structure, and then cooled to room temperature after intermediate annealing;

[0092] G is cooled to room temperature and then cold rolled to a second intermediate annealing thickness of 0.83 mm;

[0093] H. After cold rolling, it is cleaned, and then coiled and put into a box-type annealing furnace for annealing. During the annealing process, a protective atmosphere is used, and the oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305°C, it is kept warm for 4 hours to achieve a completely O-state structure, and then cooled to room temperature after intermediate annealing;

[0094] I. Cold rolling the coil to a finished product thickness of 0.25 mm;

[0095] J. After cold rolling, the steel sheet is cleaned and then coiled into a box-type annealing furnace for stabilization. The stabilization treatment system is that when the core of the steel sheet reaches 140°C, it is kept warm for 3 hours, then cooled to room temperature, and then stretched and straightened for the second time. The stretching rate of the stretching and straightening is 0.4%.

[0096] K. Cut and package the 5 series aluminum alloy strip prepared in step J.

[0097] Comparative Example 2: Using the alloy composition of the present invention + traditional production process

[0098] A. Melting, furnace refining, online degassing, online filtering are carried out according to the following aluminum alloy mass percentage, and then casting into aluminum alloy ingots.

[0099] Si: 0.067%, Fe: 0.228%, Cu: 0.083%, Mn: 0.395%, Mg: 5.11%, Cr: 0.026%, Zn: 0.015%, Ti: 0.018%, single impurity ≤ 0.03%, total impurities ≤ 0.15%, the balance is Al.

[0100] The specific smelting process is as follows: the ingredients are put into the smelting furnace in turn for smelting, and flux is used for refining and covering. After the materials in the furnace are melted, stirring begins. After refining and slagging, after obtaining qualified chemical composition, Ar gas and Cl2 mixed gas are used to bring hydrogen and fine impurities in the aluminum liquid to the surface of the melt, thereby reducing the gas content of the melt.

[0101] Furthermore, in step A, double-stage filtration is used during the casting process, including but not limited to: plate CFF filtration + plate CFF filtration, plate CFF filtration + deep bed filtration, plate CFF filtration + tubular filtration, thereby reducing the slag content of the melt, ensuring the purity of the melt, and avoiding black threads and black lines in the material structure caused by impure melt, thereby ensuring the surface quality. Al-5Ti-B is used for online refinement treatment to ensure the grain size of the aluminum alloy ingot.

[0102] B. After the aluminum alloy ingot is cooled, the head and tail are cut off, and the solidified shell layer on the surface of the ingot is removed by milling;

[0103] C. Place the sawn and milled ingot in a pusher heating furnace for uniform heating. The metal temperature is 480°C and kept warm for 3 hours.

[0104] D. Take the ingot out of the furnace and hot roll it, control the final rolling temperature of hot rolling to 325℃, and the thickness of hot rolled coil is 5.5mm;

[0105] E. Force the coil to cool to room temperature and then cold-roll it to a first intermediate thickness of 2.0 mm;

[0106] F. After cold rolling, it is cleaned, and then coiled and put into the box annealing furnace for annealing. During the annealing process, the protective atmosphere is treated, and the oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305℃, it is kept warm for 4 hours to achieve a completely O-state structure, and then cooled to room temperature after intermediate annealing;

[0107] G is cooled to room temperature and then cold rolled to a second intermediate annealing thickness of 0.83 mm;

[0108] H. After cold rolling, it is cleaned, and then coiled and put into a box-type annealing furnace for annealing. During the annealing process, a protective atmosphere is used, and the oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305°C, it is kept warm for 4 hours to achieve a completely O-state structure, and then cooled to room temperature after intermediate annealing;

[0109] I. Cold rolling the coil to a finished product thickness of 0.25 mm;

[0110] J. After cold rolling, the steel sheet is cleaned and then coiled into a box-type annealing furnace for stabilization. The stabilization treatment system is that when the core of the steel sheet reaches 140°C, it is kept warm for 3 hours, then cooled to room temperature, and then stretched and straightened for the second time. The stretching rate of the stretching and straightening is 0.4%.

[0111] K. Cut and package the 5 series aluminum alloy strip prepared in step J.

[0112] Comparative Example 3: Conventional 5182 aluminum alloy composition + production process of the present invention

[0113] A. Melting, furnace refining, online degassing, online filtering are carried out according to the following aluminum alloy mass percentage, and then casting into aluminum alloy ingots.

[0114] Si: 0.075%, Fe: 0.239%, Cu: 0.035%, Mn: 0.331%, Mg: 4.55%, Cr: 0.033%, Zn: 0.019%, Ti: 0.024%, single impurity ≤ 0.05%, total impurities ≤ 0.15%, the balance is Al.

[0115] The specific smelting process is as follows: the ingredients are put into the smelting furnace in turn for smelting, and flux is used for refining and covering. After the materials in the furnace are melted, stirring begins. After refining and slagging, after obtaining qualified chemical composition, Ar gas and Cl2 mixed gas are used to bring hydrogen and fine impurities in the aluminum liquid to the surface of the melt, thereby reducing the gas content of the melt.

[0116] Furthermore, in step A, double-stage filtration is used during the casting process, including but not limited to: plate CFF filtration + plate CFF filtration, plate CFF filtration + deep bed filtration, plate CFF filtration + tubular filtration, thereby reducing the slag content of the melt, ensuring the purity of the melt, and avoiding black threads and black lines in the material structure caused by impure melt, thereby ensuring the surface quality. Al-5Ti-B is used for online refinement treatment to ensure the grain size of the aluminum alloy ingot.

[0117] B. After the aluminum alloy ingot is cooled, the head and tail are cut off, and the solidified shell layer on the surface of the ingot is removed by milling;

[0118] C. Place the sawn and milled ingot in a pusher heating furnace for uniform heating, with the metal temperature at 510°C for 3.5 hours;

[0119] D. Take the ingot out of the furnace and hot roll it, control the final rolling temperature of hot rolling to 330°C, and the thickness of hot rolled coil is 2.6mm;

[0120] E. Force the coil to cool to room temperature and then cold roll it to a mid-roll thickness of 0.58 mm;

[0121] F. After cold rolling, it is cleaned and stretched and straightened once. The stretching rate of the stretching and straightening is 0.5%. Then, it is coiled and put into the box annealing furnace for annealing. During the annealing process, the protective atmosphere is treated and the oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305℃, it is kept warm for 4 hours to achieve a completely O-state structure. After intermediate annealing, it is cooled to room temperature;

[0122] G. Cold rolling the coil to a finished product thickness of 0.25 mm;

[0123] H. After cold rolling, the steel sheet is cleaned and straightened twice, the elongation rate of the straightening is 0.55%, and then coiled and put into a box-type annealing furnace for stabilization treatment. The stabilization treatment system is that when the core of the coil reaches 185°C, it is kept warm for 4 hours, then cooled to room temperature, and then straightened three times, the elongation rate of the straightening is 0.45%;

[0124] I. Cut and package the 5 series aluminum alloy strip prepared in step H.

[0125] The performance test results of the 5 series-H38 aluminum alloy strip produced in Examples 1 to 3 are shown in Table 1.

[0126] Table 1 Strip performance test results

[0127]

[0128] The performance test results of the 5 series-H38 aluminum alloy strips produced in Comparative Examples 1 to 3 are shown in Table 2.

[0129] Table 2 Strip performance test results

[0130]

[0131]

[0132] It can be seen from Table 1 that the strip samples produced in Examples 1 to 3 have stable mechanical properties, high elongation and good bending properties. The above is only a preferred specific implementation of the invention, but the protection scope of the invention is not limited thereto. Any technician familiar with the technical field within the technical scope disclosed by the invention, according to the technical solution and inventive concept of the invention, shall be equivalently replaced or changed, and shall be covered within the protection scope of the invention.

Claims

1. A 5 series aluminum alloy strip for a vehicle backlight panel, characterized in that: The automotive 5 series aluminum alloy has the following composition by mass percentage: Si: ≤0.12%, Fe: 0.2-0.3%, Cu: 0.07-0.09%, Mn: 0.35-0.45%, Mg: 5.05-5.15%; Cr: 0.02-0.04%; Zn≤0.03%; Ti: 0.01-0.025%, single impurity ≤0.03%, total impurities ≤0.15%, and the balance is Al.

2. A method for preparing the 5 series aluminum alloy strip for vehicle backlight panel according to claim 1, characterized in that: The following steps are involved: A. After the aluminum alloy is proportioned according to mass percentage, it is melted and refined in a furnace, and the aluminum liquid is cast into an aluminum alloy ingot; B. After the aluminum alloy ingot is cooled, the head and tail are cut off, and the solidified shell layer on the surface of the ingot is removed by milling; C. Place the sawn and milled ingot in a pusher heating furnace for uniform heating, with the metal temperature at 480°C to 530°C for 2 to 5 hours; D. Take the ingot out of the furnace and hot-roll it, control the final rolling temperature of hot rolling to 310℃~335℃, and the thickness of hot-rolled coil is 2.2mm~2.8mm; E. Force the coil to cool to room temperature and then cold roll it; F. After cold rolling, it is cleaned, stretched and straightened once, and then coiled and put into a box-type annealing furnace for annealing. During the annealing process, a protective atmosphere is used, and the oxygen content is ≤0.3%. The annealing system is that when the core of the coil reaches 305°C, it is kept warm for 4 hours to achieve a completely O-state structure, and then cooled to room temperature after intermediate annealing; G. Cold rolling the coil to the finished thickness; H. After cold rolling, it is cleaned, and after coiling, it is put into a box-type annealing furnace for stabilization treatment, and then cooled to room temperature after stabilization; after cold rolling, it is cleaned, stretched and straightened for the second time, and after coiling, it is put into a box-type annealing furnace for stabilization treatment, and then cooled to room temperature after stabilization; I. Cut and package the 5 series aluminum alloy strip prepared in step H.

3. The method for preparing a 5 series aluminum alloy strip for a vehicle backlight panel according to claim 2, characterized in that: In the step E, the cold rolling is performed to the intermediate thickness, and the cold rolling processing rate from the intermediate thickness to the finished product thickness is reserved at 50% to 60%.

4. The method for preparing a 5 series aluminum alloy strip for a vehicle backlight panel according to claim 3, characterized in that: The center retreat thickness is 0.40 mm to 0.75 mm.

5. The method for preparing a 5 series aluminum alloy strip for a vehicle backlight panel according to claim 2, characterized in that: The stabilization treatment system in step H is to keep the core of the coil at 150-200° C. for 4 hours.

6. The method for preparing a 5 series aluminum alloy strip for a vehicle backlight panel according to claim 2, characterized in that: In the step H, the strip after stabilization treatment is stretched and straightened three times.

7. The method for preparing a 5 series aluminum alloy strip for a vehicle backlight panel according to claim 6, characterized in that: In the step H, the secondary stretching straightening stretching ratio is 0.4% to 0.6%.

8. The method for preparing a 5 series aluminum alloy strip for a vehicle backlight panel according to claim 6, characterized in that: In the step H, the stretching ratio of the three-stretching straightening is 0.3% to 0.5%.

9. The method for preparing a 5 series aluminum alloy strip for a vehicle backlight panel according to claim 1, characterized in that: In the step F, the stretching rate of the primary stretching straightening is 0.3% to 0.5%.

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