Cast rolling method for high-solid-solution high-alloy aluminum alloy plate blank

Abstract

The invention discloses a cast rolling method for a high-solid-solution high-alloy aluminum alloy plate blank. The cast rolling method comprises the steps that S1, aluminum alloy is smelted into aluminum alloy melt; s2, after heat preservation is conducted on the aluminum alloy melt for a period of time, slagging-off is conducted, then the aluminum alloy melt is transferred into a heat preservation furnace to stand for a period of time, degassing is conducted, and then the aluminum alloy melt is conveyed to a front box; s3, the aluminum alloy melt in the front box is conveyed into a casting nozzle through a gutter channel, plate standing is conducted, a grain refiner is added into the gutter channel, and the plate outlet thickness of a cast-rolled plate is not larger than 5 mm by controlling a roll gap; and S4, cast rolling is started, the cast rolling speed is not smaller than 1 m / min, meanwhile, a water spraying cooling device in a roller is started, when the plate blank reaches a certain length, cast rolling is stopped, the plate blank before coiling is forcibly cooled through low-temperature airflow flowing out of the cold air end of the vortex pipe, and the high-solid-solution high-alloy aluminum alloy plate blank is obtained. According to the method, the solid solubility of alloy elements in the aluminum alloy plate blank can be improved, and strip segregation of the surface and the center of the plate blank is effectively avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy casting and rolling, and particularly relates to a casting and rolling method for a high-solid-solution high-alloy aluminum alloy slab. Background Art

[0002] At present, the main methods for supplying industrial aluminum alloy sheets are hot rolling and cast-rolling. The hot rolling process mainly includes semi-continuous ingot casting, homogenization heat treatment, blanking, milling, hot rolling, etc. It has many processes, large one-time investment, and high energy consumption, so the production cost is high and the carbon emissions are high. The cast-rolling method is to pour the liquid aluminum alloy directly into two rollers with cooling water flowing inside, and directly and continuously produce slabs under the action of cooling and pressure. Usually, the thickness of the slab produced by the cast-rolling method is 6-8mm. Compared with the hot rolling method, the cast-rolling method does not need to go through a series of processes such as homogenization heat treatment, blanking, milling, hot rolling, etc., which can effectively reduce carbon emissions in the production process and has the advantages of energy saving and environmental protection. In addition, the cast-rolling method has the advantages of low investment and short process, which greatly reduces production costs.

[0003] High-alloy aluminum alloy sheets, such as the 3xxx, 5xxx, 6xxx, and 7xxx series aluminum alloys, possess excellent strength and ductility and are widely used in high-end manufacturing applications such as aerospace, new energy vehicles, and power battery housings. However, the quality of high-alloy aluminum slabs produced by existing cast-rolling methods remains inferior to that of hot rolling methods. This difficulty stems primarily from the high number of alloying elements added to high-alloy aluminum alloys, which leads to severe macro- and micro-segregation in the cast-rolled slabs. This can cause cracking during subsequent rolling or processing, or result in substandard mechanical properties in the final product.

[0004] High-solution aluminum alloys are expected to address the segregation problem in cast-rolled aluminum alloy slabs by increasing the solubility of alloying elements within aluminum grains. However, the main technical challenge lies in the fact that during the casting and rolling process, the aluminum alloy slab solidifies from the outside inward, which easily forms macrosegregation. Furthermore, as the content of alloying elements such as Mg and Cu increases, the tendency for microsegregation in the aluminum alloy slab also increases significantly. Conventional casting and rolling processes are unable to produce high-solution aluminum alloy slabs. Summary of the Invention

[0005] In view of the above-mentioned defects of the prior art, the present invention provides a casting and rolling method for high solid solution high alloy aluminum alloy slabs, which can improve the solid solubility of alloying elements in the aluminum alloy slabs and effectively avoid band segregation on the surface and center of the slabs.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A casting and rolling method for a high solid solution high alloy aluminum alloy slab comprises the following steps:

[0008] S1. Batching and smelting: an aluminum alloy is batched according to the proportion of each component content, and smelted into an aluminum alloy melt. After sampling the aluminum alloy melt to detect the alloy composition, a master alloy is added to adjust the alloy composition of the aluminum alloy melt to the following mass percentages: Mg 0.5-1.5%, Si 0.8-1.5%, Cu 0.25-0.9%, Mn 0.2-1.2%, Cr 0.05-0.5%, Fe 0.1-0.8%, Ti+V≤0.2%, Zr≤0.25%, Zn≤0.2%, Sc≤0.1%, and the balance is Al;

[0009] S2. Transfer and refining: The aluminum alloy melt is kept warm for a period of time and then slag is removed. The aluminum alloy melt is then transferred to a holding furnace controlled at 700-750°C and allowed to stand for a period of time for degassing. The aluminum alloy melt is then transferred to a head box controlled at 700-750°C through a chute.

[0010] S3. Plate Standing: The aluminum alloy melt in the front box is conveyed into the casting nozzle of the casting and rolling mill through a water trough for plate standing to form a solidified shell of a certain thickness on the surface of the slab. An Al-Ti-VB grain refiner is added to the water trough. The temperature of the aluminum alloy melt when it reaches the casting nozzle inlet is controlled to be no less than 40°C above the liquidus. The gap between the casting rollers in the casting and rolling mill is controlled to ensure that the thickness of the cast plate is no more than 5mm.

[0011] S4. Casting and rolling: After the slab is successfully erected, casting and rolling are started. The casting and rolling speed is not less than 1m / min. At the same time, the water spray cooling device in the casting and rolling mill roller is turned on to control the cooling water temperature to be no higher than 35°C. When the slab reaches a certain length, casting and rolling is stopped, and the low-temperature airflow flowing out of the cold air end of the vortex tube is used to force the slab before coiling to be quickly cooled to obtain a high solid solution and high alloy aluminum alloy slab.

[0012] Furthermore, in step S1: the alloy composition of the aluminum alloy melt is adjusted to the following mass percentages: Mg 0.9-1.3%, Si 0.9-1.2%, Cu 0.3-1.1%, Mn 0.7-1.0%, Cr 0.05-0.25%, Fe 0.4-0.7%, Ti+V≤0.2%, Zr≤0.25%, Zn≤0.2%, Sc≤0.1%, and the balance is Al.

[0013] Furthermore, in step S2: the temperature of the front box is controlled at 710-735°C.

[0014] Furthermore, in step S3: the gap between the casting rolls is controlled to be 1-3 mm.

[0015] Furthermore, in step S3: the thickness of the cast plate is controlled to be 2-4 mm.

[0016] Furthermore, in step S4: the thickness of the quenching layer in the obtained high solid solution high alloy aluminum alloy slab accounts for 15-80%, and the thickness of the quenching layer on one side is 0.3-1.1 mm.

[0017] Furthermore, in step S3: the thickness of the cast plate is controlled to be 2-3 mm.

[0018] Furthermore, in step S4: the thickness of the quenching layer in the obtained high solid solution high alloy aluminum alloy slab accounts for 30-100%, and the thickness of the quenching layer on one side is 0.5-1 mm.

[0019] Furthermore, in step S4: the cooling water temperature is controlled at 20-32°C, the casting speed is controlled at 1.5-3m / min, and the temperature of the low-temperature airflow flowing out of the cold air end of the vortex tube is as low as -50°C.

[0020] Furthermore, in step S4: a pulse power supply device is set at the inflow side of the aluminum alloy melt, and the pulse power supply is turned on during the casting process, and the AC frequency is controlled to be 10-40Hz and the current density is 0.1-0.5A / mm 2 .

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] In the present invention, the solidification cooling rate of the upper and lower surfaces of the cast-rolled plate is greater than the cooling rate of the core of the cast-rolled plate, and a quenching layer is formed on the surface. By controlling the gap between the casting rollers in the casting and rolling machine, the thickness of the cast-rolled plate is not more than 5 mm. In this way, by reducing the thickness of the cast-rolled plate, the proportion of the quenching layer in the thickness direction of the high-alloy aluminum alloy slab can be increased, and the solid solubility of the alloy elements in the high-alloy aluminum alloy slab can be increased. The low-temperature airflow flowing out from the cold air end of the vortex tube is forced to cool the slab before coiling, which can also increase the proportion of the quenching layer in the thickness direction of the high-alloy aluminum alloy slab and increase the solid solubility of the alloy elements in the high-alloy aluminum alloy slab. Since the casting speed is not less than 1 m / min and the cooling water temperature is not higher than 35°C, by increasing the casting speed and reducing the cooling water temperature, the cooling rate of the surface of the high-alloy aluminum alloy slab can be increased, and the thickness of the quenching layer can be increased. At the same time, the non-quenching layer in the core of the slab The cooling rate of the region will also be accelerated, which is beneficial to improving the solid solution of alloy elements and reducing segregation; since Al-Ti-VB grain refiner is added to the water trough, it can provide sufficient nucleation particles for the casting and rolling solidification process, reduce the segregation tendency of alloy elements, and realize the refinement of the structure of primary solidified crystals in the water trough; since the temperature of the front box is controlled at 700-750℃, by increasing the temperature of the front box to above 700℃, the temperature of the aluminum alloy melt finally transported into the casting nozzle can be increased, which is beneficial to the flow of the aluminum alloy melt, preventing insufficient fluidity caused by high alloy content, and avoiding the aluminum alloy melt from sticking to the casting nozzle during subsequent casting and rolling production. Moreover, by controlling the temperature of the front box to no more than 750℃, the temperature of the aluminum alloy melt in the front box can be prevented from being too high, thereby avoiding the oxidation of alloy components such as Mg, the excessive thickness of the oxide film on the surface of the aluminum alloy melt, and the increase of the hydrogen content of the aluminum alloy melt. In summary, the present invention successfully produces high-solution high-alloy aluminum alloy slabs using the cast-rolling method by comprehensively controlling process parameters such as cast-rolled plate thickness, casting temperature, cast-rolling speed, roll cooling water temperature, and forced rapid cooling before slab coiling, effectively avoiding banded segregation on the surface and center of the slab.

[0023] In the present invention, the casting and rolling speed is controlled at 1.5-3m / min. By controlling the casting and rolling speed to no more than 3m / min, the problem of insufficient solidification and formation of tropical defects on the slab surface caused by excessively fast casting and rolling speed can be prevented; the cooling water temperature is controlled at 20-32°C, which does not require complicated cooling equipment and processes and is suitable for actual production; the temperature of the low-temperature air flow flowing out of the cold air end of the vortex tube is as low as -50°C. Due to the effect of forced cooling, the proportion of the quenching layer in the thickness direction of the high-alloy aluminum alloy slab can be significantly increased, and the solid solubility of the alloying elements in the high-alloy aluminum alloy slab can be increased, so as to reduce segregation at the upper surface, lower surface and center position of the aluminum alloy slab.

[0024] In the present invention, a pulse power supply device is set at the inflow side of the aluminum alloy melt, and the pulse power supply is turned on during the casting and rolling process to control the AC frequency to 10-40Hz and the current density to 0.1-0.5A / mm 2 ; In this way, low-frequency alternating current can make the distribution of alloying elements in the cast-rolled aluminum alloy slab more uniform, thereby increasing the solid solution content of alloying elements in the crystal and reducing the macro and micro segregation of alloying elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The metallographic images of an 8 mm thick aluminum alloy slab obtained by a conventional casting and rolling method in the background art at different thickness positions are shown;

[0026] Figure 2 Figure 4 shows metallographic images of a 4 mm thick high solid solution aluminum alloy slab produced by the method of the present invention at different thickness positions, wherein in step S4, the low-temperature airflow that does not flow through the cold air end of the vortex tube forcibly cools the slab before coiling;

[0027] Figure 3 The metallographic diagrams at different thickness positions of a high solid solution aluminum alloy slab with a thickness of 4 mm produced by the method of the present invention are shown, wherein in step S4, the slab before coiling is forcibly cooled by the low-temperature airflow flowing out of the cold air end of the vortex tube. DETAILED DESCRIPTION

[0028] The following is a further detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, and are not intended to limit the present invention.

[0029] A casting and rolling method for a high solid solution high alloy aluminum alloy slab comprises the following steps:

[0030] S1. Batching and smelting: an aluminum alloy is batched according to the proportion of each component content, and smelted into an aluminum alloy melt. After sampling the aluminum alloy melt to detect the alloy composition, a master alloy is added to adjust the alloy composition of the aluminum alloy melt to the following mass percentages: Mg 0.5-1.5%, Si 0.8-1.5%, Cu 0.25-0.9%, Mn 0.2-1.2%, Cr 0.05-0.5%, Fe 0.1-0.8%, Ti+V≤0.2%, Zr≤0.25%, Zn≤0.2%, Sc≤0.1%, and the balance is Al;

[0031] S2, transfer and refining: the aluminum alloy melt in step S1 is kept warm for a period of time, then slag is removed, and then the aluminum alloy melt is transferred to a holding furnace controlled at a temperature of 700-750°C, left to stand for a period of time, and then degassed. The aluminum alloy melt is then transferred to a head box controlled at a temperature of 700-750°C via a chute;

[0032] S3. Plate Standing: The aluminum alloy melt in the front box is conveyed into the casting nozzle of the casting and rolling mill through a water trough for plate standing to form a solidified shell of a certain thickness on the surface of the slab. An Al-Ti-VB grain refiner is added to the water trough. The temperature of the aluminum alloy melt when it reaches the casting nozzle inlet is controlled to be no less than 40°C above the liquidus. The gap between the casting rollers in the casting and rolling mill is controlled to ensure that the thickness of the cast plate is no more than 5mm.

[0033] S4. Casting and rolling: After the slab is successfully erected, start casting and rolling. The casting and rolling speed is not less than 1m / min. At the same time, turn on the water spray cooling device in the casting and rolling mill rolls to control the cooling water temperature to be no higher than 35°C. When the slab reaches a certain length, stop casting and rolling, and force the slab before coiling to cool by the low-temperature airflow flowing out of the cold air end of the vortex tube to obtain a high solid solution and high alloy aluminum alloy slab.

[0034] In the present invention, the solidification cooling rate of the upper and lower surfaces of the cast-rolled plate is greater than the cooling rate of the core of the cast-rolled plate, and a quenching layer is formed on the surface. By controlling the gap between the casting rollers in the casting and rolling mill, the thickness of the cast-rolled plate is made not more than 5 mm. In this way, by reducing the thickness of the cast-rolled plate, the proportion of the quenching layer in the thickness direction of the high-alloy aluminum alloy slab can be increased, and the solid solubility of the alloying elements in the high-alloy aluminum alloy slab can be increased. The low-temperature airflow flowing out of the cold air end of the vortex tube is forced to cool the slab before coiling, which can also increase the Increase the proportion of the quench layer in the thickness direction of the high-alloy aluminum alloy slab and increase the solid solubility of the alloying elements in the high-alloy aluminum alloy slab; since the casting and rolling speed is not less than 1m / min and the cooling water temperature is not higher than 35°C, by increasing the casting and rolling speed and lowering the cooling water temperature, the cooling rate of the surface of the high-alloy aluminum alloy slab can be increased, and the thickness of the quench layer can be increased. At the same time, the cooling rate of the non-quench layer area in the core of the slab will also be accelerated, which is beneficial to improve the solid solubility of the alloying elements and reduce segregation; due to the addition of Al-Ti- VB grain refiner can provide sufficient nucleation points for the casting and rolling solidification process, reduce the segregation tendency of alloy elements, and realize the refinement of the structure of the primary solidified crystal in the water trough. Specifically, during the process of the aluminum alloy melt being transported from the front box through the water trough to the casting nozzle, the temperature will slowly drop and solidify and precipitate relatively coarse grains. By adding Al-Ti-VB grain refiner in the water trough, it is beneficial to refine the grains, thereby improving the performance of the cast and rolled plate; since the temperature of the front box is controlled at 700-750℃, Increasing the temperature of the front box to above 700°C can increase the temperature of the aluminum alloy melt that is finally transported into the casting nozzle, which is beneficial to the flow of the aluminum alloy melt, prevents insufficient fluidity due to high alloy content, and avoids the aluminum alloy melt from sticking to the casting nozzle during the subsequent casting and rolling production process. Moreover, by controlling the temperature of the front box to no more than 750°C, the temperature of the aluminum alloy melt in the front box can be prevented from being too high, thereby avoiding the oxidation of alloy components such as Mg, the excessive thickness of the oxide film on the surface of the aluminum alloy melt, and the increase in the hydrogen content of the aluminum alloy melt. In summary, the present invention successfully produces high-solution high-alloy aluminum alloy slabs using the casting and rolling method by comprehensively regulating process parameters such as the thickness of the cast-rolled plate, the casting temperature, the casting and rolling speed, the temperature of the cooling water of the rolls, and the forced rapid cooling before the slab is coiled, effectively avoiding banded segregation on the surface and center of the slab.

[0035] Wherein, in step S1: the alloy composition of the aluminum alloy melt is adjusted to the following mass percentages: Mg 0.9-1.3%, Si 0.9-1.2%, Cu 0.3-1.1%, Mn 0.7-1.0%, Cr 0.05-0.25%, Fe 0.4-0.7%, Ti+V≤0.2%, Zr≤0.25%, Zn≤0.2%, Sc≤0.1%, and the balance is Al.

[0036] Since the macro- and micro-segregation caused by high alloy can be avoided by enhancing the solid solubility of alloying elements in the aluminum alloy slab, a higher content of alloying elements such as Mg, Si, Cu, Mn, and Cr can be achieved in the aluminum alloy slab produced by this method; at the same time, by enhancing the solid solubility of alloying elements in the aluminum alloy slab, the solid solution strengthening effect of elements such as Mg and Mn, as well as the aging strengthening effect of elements such as Mg, Si, and Cu can be enhanced.

[0037] In aluminum alloy slabs, high contents of Mn and Cr can improve the Fe phase morphology, increase the upper limit of Fe content, and thus increase the proportion of waste in the raw materials. Therefore, in step S1, the proportion of waste can reach 60%, and the rest is industrial pure aluminum ingots or electrolytic aluminum liquid. Increasing the proportion of waste can reduce carbon emissions and make casting and rolling production more environmentally friendly.

[0038] In step S2, the temperature of the front box is controlled at 710-735°C. This not only helps to ensure the fluidity of the aluminum alloy melt, but also better avoids the oxidation of alloy components such as Mg, excessively thick oxide film on the surface of the aluminum alloy melt, and excessive hydrogen content in the aluminum alloy melt caused by excessive front box temperature.

[0039] in,

[0040] In step S3: the thickness of the cast plate is controlled to be 2-4 mm.

[0041] In step S4: the thickness of the quenching layer in the obtained high solid solution high alloy aluminum alloy slab accounts for 15-80%, and the thickness of the quenching layer on one side is 0.3-1.1 mm.

[0042] or,

[0043] In step S3: the thickness of the cast plate is controlled at 2-3 mm.

[0044] In step S4: the thickness of the quenching layer in the obtained high solid solution high alloy aluminum alloy slab accounts for 30-100%, and the thickness of the quenching layer on one side is 0.5-1 mm.

[0045] Among them, since the aluminum alloy slab will bounce when passing through the roll gap, causing the actual slab thickness to be greater than the roll gap, in step S3, the roll gap of the casting roll is controlled to be 1-3 mm.

[0046] Among them, in step S4: the cooling water temperature is controlled at 20-32°C, and the casting and rolling speed is controlled at 1.5-3m / min. By controlling the casting and rolling speed to no more than 3m / min, the casting and rolling speed can be prevented from being too fast, resulting in insufficient solidification and the formation of tropical defects on the slab surface; by controlling the cooling water temperature at 20-32°C, no complicated cooling equipment and process are required, which is suitable for actual production; the temperature of the low-temperature air flow flowing out of the cold air end of the vortex tube is as low as -50°C. Due to the effect of forced cooling, the proportion of the quenching layer in the thickness direction of the high-alloy aluminum alloy slab can be significantly increased, and the solid solubility of the alloying elements in the high-alloy aluminum alloy slab can be increased to reduce the segregation at the upper surface, lower surface and center position of the aluminum alloy slab.

[0047] In step S4, a pulse power supply device is set at the inflow side of the aluminum alloy melt, and the pulse power supply is turned on during the casting process, and the AC frequency is controlled to be 10-40Hz and the current density is 0.1-0.5A / mm 2 In this way, low-frequency alternating current can make the distribution of alloying elements in the cast-rolled aluminum alloy slab more uniform, thereby increasing the solid solution content of alloying elements in aluminum grains and reducing the macro- and micro-segregation of alloying elements.

[0048] The casting rolls are made of copper sleeves. Since the thermal conductivity of copper is several times that of steel, the use of copper sleeves can significantly increase the solidification and cooling speed of cast aluminum alloy slabs.

[0049] Wherein, in step S3: the Al-Ti-VB grain refiner is specifically Al-1.25%Ti-1wt%V-1wt%B grain refiner.

[0050] The high-alloy aluminum slab produced by this method features a high solid solution fraction, with the total volume percentage of the eutectic phase within the aluminum alloy slab being no greater than 5%. These eutectic phases primarily include Mg2Si, AlFeSi, Al3Mn, and other components, and their volume fractions can be measured using metallographic methods. This high solid solution fraction results in a lower eutectic phase volume fraction, less segregation, and shortened subsequent solution treatment time.

[0051] The high solid solution high alloy aluminum alloy slab produced by this method has a yield strength of 80-150 MPa and an elongation of 10-30%. The yield strength is relatively low in the high solid solution state and is suitable for direct cold rolling. At the same time, since this method can effectively reduce macro and micro segregation, the elongation of the aluminum alloy slab can be effectively improved.

[0052] Figure 1 The metallographic diagrams of the aluminum alloy slab with a thickness of 8 mm obtained by the conventional casting and rolling method in the background art at different thickness positions are shown. Figure 1 (a) shows the metallographic image of the upper surface of the aluminum alloy slab. Figure 1(b) shows the metallographic image at a position 1 / 4 of the thickness from the upper surface of the aluminum alloy slab. Figure 1 (c) shows the metallographic image at the center of the aluminum alloy slab. Figure 1 (d) represents the metallographic image at a position 1 / 4 of the thickness from the lower surface of the aluminum alloy slab. Figure 1 (e) represents the metallographic image of the lower surface of the aluminum alloy slab. Figure 1 There is segregation at the positions indicated by arrows in (a), (b) and (e). Figure 1 There is segregation at the circled position in (c). Figure 1 It can be seen that segregation exists on the upper surface of the aluminum alloy slab, at a position 1 / 4 of the thickness from the upper surface of the aluminum alloy slab, at the center of the aluminum alloy slab, and at the lower surface of the aluminum alloy slab.

[0053] Figure 2 The metallographic images of the high solid solution aluminum alloy slab with a thickness of 4 mm produced by the method of the present invention at different thickness positions are shown, wherein in step S4, the low-temperature airflow that does not flow out of the cold air end of the vortex tube is forced to cool the slab before coiling, wherein Figure 2 (a) shows the metallographic image of the upper surface of the aluminum alloy slab. Figure 2 (b) shows the metallographic image at a position 1 / 4 of the thickness from the upper surface of the aluminum alloy slab. Figure 2 (c) shows the metallographic image at the center of the aluminum alloy slab. Figure 2 (d) represents the metallographic image at a position 1 / 4 of the thickness from the lower surface of the aluminum alloy slab. Figure 2 (e) represents the metallographic image of the lower surface of the aluminum alloy slab. Figure 2 There is segregation at the circled position in (c). Figure 2 It can be seen that segregation exists at the center of the aluminum alloy slab.

[0054] Figure 3 The metallographic images of the high solid solution aluminum alloy slab with a thickness of 4 mm prepared by the method of the present invention at different thickness positions are shown, wherein in step S4, the slab before coiling is forcedly cooled by the low-temperature air flow flowing out of the cold air end of the vortex tube, wherein Figure 3 (a) shows the metallographic image of the upper surface of the aluminum alloy slab. Figure 3 (b) shows the metallographic image at a position 1 / 4 of the thickness from the upper surface of the aluminum alloy slab. Figure 3 (c) shows the metallographic image at the center of the aluminum alloy slab. Figure 3 (d) represents the metallographic image at a position 1 / 4 of the thickness from the lower surface of the aluminum alloy slab. Figure 3 (e) shows the metallographic diagram of the lower surface of the aluminum alloy slab. Figure 3It can be seen that due to the effect of forced cooling, the segregation on the upper surface, lower surface and center of the aluminum alloy slab is significantly reduced.

[0055] Example 1

[0056] A method for casting and rolling a 6xxx aluminum alloy slab having a slab thickness of 2.5 mm comprises the following steps:

[0057] S1. Batch smelting: melt industrial pure aluminum ingots and scrap at 750°C to form an aluminum alloy melt, wherein the scrap accounts for 60%. After sampling the aluminum alloy melt to test the alloy composition, add the master alloy to adjust the alloy composition of the aluminum alloy melt to the following percentage by mass: Mg 0.9%, Si 1.0%, Cu 0.6%, Mn 0.6%, Cr 0.1%, Fe 0.5%, Ti+V≤0.15%, Zn≤0.2%, and the balance is Al;

[0058] S2, transfer and refining: the aluminum alloy melt in step S1 is kept warm for 2 hours and then deslagging is performed, and then the aluminum alloy melt is transferred to a holding furnace and allowed to stand for 2 hours for degassing, and then the aluminum alloy melt is transferred to a head box through a chute, wherein the temperature of the aluminum alloy melt upon reaching the head box is controlled at 735±2°C;

[0059] S3. Plate Standing: The aluminum alloy melt in the front box is conveyed into the casting nozzle of the casting mill through a water trough for plate standing to form a solidified shell of a certain thickness on the surface of the slab. An Al-Ti-VB grain refiner is added to the water trough. The temperature of the aluminum alloy melt is controlled to be 710-720°C when it reaches the casting nozzle inlet. The casting rolls of the casting mill use copper roller sleeves, the gap between the casting rolls is controlled to be 1mm, and the thickness of the cast plate is controlled to be 2.5mm.

[0060] S4. Casting and rolling: After the slab is successfully erected, when the length of the cast slab rolling zone exceeds 100mm, casting and rolling begins. The casting and rolling speed is set to 2.5m / min. At the same time, the water spray cooling device in the roll of the casting and rolling mill is turned on, and the cooling water temperature is controlled to 23℃. The pressure in the direction of the billet is sprayed to 0.4MPa. A pulse power supply device is set on the side where the aluminum alloy melt flows in. The pulse power supply is turned on during the casting and rolling process, and the AC frequency is controlled to 20Hz and the current density is 0.2A / mm 2 When the slab reaches a certain length, the casting and rolling is stopped, and the low-temperature air flow with a temperature as low as -50°C flowing out from the cold air end of the vortex tube is forced to cool the slab before coiling to obtain a high solid solution high alloy aluminum alloy slab.

[0061] The 6xxx aluminum alloy slab prepared by the casting and rolling method of the present invention has a total volume percentage of the eutectic phase of 2.3%, no central band segregation, and a total thickness of the upper and lower sides of the quench layer of 1.7 mm. The thickness of the quench layer in the obtained high solid solution high alloy aluminum alloy slab accounts for 68%, and the yield strength of the obtained high solid solution high alloy aluminum alloy slab is 93 MPa, and the elongation is 26%.

[0062] Example 2

[0063] A method for casting and rolling a 6xxx aluminum alloy slab having a slab thickness of 3 mm comprises the following steps:

[0064] S1. Batch smelting: melt industrial pure aluminum ingots and scrap at 750°C to form an aluminum alloy melt, wherein the scrap accounts for 60%. After sampling the aluminum alloy melt to test the alloy composition, add the master alloy to adjust the alloy composition of the aluminum alloy melt to the following percentage by mass: Mg 0.8%, Si 1.0%, Cu 0.7%, Mn 0.4%, Cr 0.07%, Fe 0.4%, Ti+V≤0.1%, Zn≤0.15%, and the balance is Al;

[0065] S2, transfer and refining: the aluminum alloy melt in step S1 is kept warm for 2 hours and then deslagging is performed, and then the aluminum alloy melt is transferred to a holding furnace and allowed to stand for 2 hours for degassing, and then the aluminum alloy melt is transferred to a head box through a chute, wherein the temperature of the aluminum alloy melt upon reaching the head box is controlled at 725±2°C;

[0066] S3. Plate Standing: The aluminum alloy melt in the front box is conveyed into the casting nozzle of the casting mill through a water trough for plate standing to form a solidified shell of a certain thickness on the surface of the slab. An Al-Ti-VB grain refiner is added to the water trough. The temperature of the aluminum alloy melt is controlled to be 710-720°C when it reaches the casting nozzle inlet. The casting rolls of the casting mill use copper roller sleeves, the gap between the casting rolls is controlled to be 1.5mm, and the thickness of the cast plate is controlled to be 3mm.

[0067] S4. Casting and rolling: After the slab is successfully erected, when the length of the cast slab rolling zone exceeds 100mm, casting and rolling begins. The casting and rolling speed is set to 2m / min. At the same time, the water spray cooling device in the casting and rolling mill roll is turned on, and the cooling water temperature is controlled to 27℃. The pressure in the billet-out direction is 0.3MPa. A pulse power supply device is set on the side where the aluminum alloy melt flows in. The pulse power supply is turned on during the casting and rolling process, and the AC frequency is controlled to 30Hz and the current density is 0.1A / mm 2 When the slab reaches a certain length, the casting and rolling is stopped, and the low-temperature air flow with a temperature as low as -50°C flowing out from the cold air end of the vortex tube is forced to cool the slab before coiling to obtain a high solid solution high alloy aluminum alloy slab.

[0068] The 6xxx aluminum alloy slab prepared by the casting and rolling method of the present invention has a total volume percentage of the eutectic phase of 2.8%, no central band segregation, and a total thickness of the upper and lower sides of the quench layer of 1.7 mm. The thickness of the quench layer in the obtained high solid solution high alloy aluminum alloy slab accounts for 57%, and the yield strength of the obtained high solid solution high alloy aluminum alloy slab is 102 MPa, and the elongation is 25%.

[0069] Example 3

[0070] A method for casting and rolling a 6xxx aluminum alloy slab having a slab thickness of 3.5 mm comprises the following steps:

[0071] S1. Batch smelting: melt industrial pure aluminum ingots and scrap at 750°C to form an aluminum alloy melt, wherein the scrap accounts for 60%. After sampling the aluminum alloy melt to test the alloy composition, add the master alloy to adjust the alloy composition of the aluminum alloy melt to the following percentage by mass: Mg 0.8%, Si 0.9%, Cu 0.3%, Mn 0.3%, Cr 0.06%, Fe 0.3%, Ti+V≤0.1%, Zn≤0.15%, and the balance is Al;

[0072] S2, transfer and refining: the aluminum alloy melt in step S1 is kept warm for 2 hours and then deslagging is performed, and then the aluminum alloy melt is transferred to a holding furnace and allowed to stand for 2 hours for degassing, and then the aluminum alloy melt is transferred to a head box through a chute, wherein the temperature of the aluminum alloy melt arriving at the head box is controlled at 715±2°C;

[0073] S3. Plate Standing: The aluminum alloy melt in the front box is conveyed into the casting nozzle of the casting mill through a water trough for plate standing to form a solidified shell of a certain thickness on the surface of the slab. An Al-Ti-VB grain refiner is added to the water trough, and the temperature of the aluminum alloy melt is controlled to be 710-720°C when it reaches the casting nozzle inlet. The casting rolls of the casting mill use copper roller sleeves, the gap between the casting rolls is controlled to be 1.9mm, and the thickness of the cast plate is controlled to be 3.5mm.

[0074] S4. Casting and rolling: After the slab is successfully erected, when the length of the cast and rolled slab out of the rolling zone exceeds 100 mm, casting and rolling is started, and the casting and rolling speed is set to 2.5 m / min. At the same time, the water spray cooling device in the roll of the casting and rolling machine is turned on, and the cooling water temperature is controlled to 30 ° C. The pressure sprayed in the direction of the billet is 0.35 MPa. No pulse power supply device is set on the side where the aluminum alloy melt flows in. When the slab reaches a certain length, casting and rolling is stopped, and the low-temperature air flow with a temperature as low as -50 ° C flowing out from the cold air end of the vortex tube is forced to cool the slab before coiling to obtain a high solid solution and high alloy aluminum alloy slab.

[0075] The 6xxx aluminum alloy slab prepared by the casting and rolling method of the present invention has a total volume percentage of the eutectic phase of 2.7%, no central band segregation, and a total thickness of the upper and lower sides of the quench layer of 1.5 mm. The thickness of the quench layer in the obtained high solid solution high alloy aluminum alloy slab accounts for 43%, and the obtained high solid solution high alloy aluminum alloy slab has a yield strength of 103 MPa and an elongation of 24%.

[0076] Example 4

[0077] A casting and rolling method for a non-standard grade aluminum alloy slab having a slab thickness of 3.5 mm comprises the following steps:

[0078] S1. Smelting of ingredients: melt industrial pure aluminum ingots and scrap at 750°C to form an aluminum alloy melt, wherein the scrap accounts for 60%. After sampling the aluminum alloy melt to test the alloy composition, add the master alloy to adjust the alloy composition of the aluminum alloy melt to the mass percentage shown in Table 1, with the remainder being Al;

[0079] Table 1

[0080] Mg Si Cu Mn Cr Fe Ti+V Zn Alloy 1 1.2％ 0.9％ 0.4％ 0.5％ 0.1％ 0.4％ ≤0.2％ ≤0.15％ Alloy 2 1.2％ 1.0％ 0.6％ 0.6％ 0.1％ 0.6％ ≤0.2％ ≤0.15％ Alloy 3 1.3％ 1.1％ 0.8％ 0.9％ 0.2％ 0.6％ ≤0.2％ ≤0.15％

[0081] S2, transfer and refining: each aluminum alloy melt in step S1 is kept warm for 2 hours and then deslagging is performed. Then, each aluminum alloy melt is transferred to a holding furnace and allowed to stand for 2 hours for degassing. After that, each aluminum alloy melt is transferred to a head box through a chute. The temperature of each aluminum alloy melt upon arrival at the head box is controlled at 735±2°C.

[0082] S3. Plate Standing: Each aluminum alloy melt in the front box is conveyed into the casting nozzle of the casting mill through a water trough, and plate standing is performed to form a solidified shell of a certain thickness on the surface of the slab. An Al-Ti-VB grain refiner is added to the water trough, and the temperature of each aluminum alloy melt is controlled to be 720-725°C when it reaches the casting nozzle inlet. The casting rolls of the casting mill use copper roller sleeves, the gap between the casting rolls is controlled to be 1.9mm, and the plate thickness of each cast plate is controlled to be 3.5mm;

[0083] S4. Casting and rolling: After the slab is successfully erected, when the length of the rolling zone of each cast slab exceeds 100mm, casting and rolling begins. The casting and rolling speed is set to 2.8m / min. At the same time, the water spray cooling device in the roll of the casting and rolling mill is turned on, and the cooling water temperature is controlled to 22℃. The pressure in the direction of the billet is sprayed to 0.4MPa. A pulse power supply device is set on the side where the aluminum alloy melt flows in. The pulse power supply is turned on during the casting and rolling process, and the AC frequency is controlled to 10Hz and the current density is 0.5A / mm 2 When the slab reaches a certain length, the casting and rolling is stopped, and the low-temperature air flow with a temperature as low as -50°C flowing out from the cold air end of the vortex tube is forced to cool each slab before coiling to obtain each high solid solution high alloy aluminum alloy slab.

[0084] The aluminum alloy slabs prepared by the casting and rolling method of the present invention have no central band segregation. The total thickness of the upper and lower sides of the quench layer in each aluminum alloy slab, the thickness ratio of the quench layer in each aluminum alloy slab, the yield strength and elongation of each aluminum alloy slab are shown in Table 2 respectively.

[0085] Table 2

[0086] Total thickness of upper and lower sides of quench layer / mm Thickness of quench layer / % Yield strength / MPa Elongation / % Alloy 1 2.1 60％ 107 25 Alloy 2 2.2 63％ 111 26 Alloy 3 2.1 60％ 120 23

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A casting and rolling method for high solid solution high alloy aluminum alloy slab, characterized in that: The following steps are involved: S1. Batching and smelting: an aluminum alloy is batched according to the proportion of each component content, and smelted into an aluminum alloy melt. After sampling the aluminum alloy melt to detect the alloy composition, a master alloy is added to adjust the alloy composition of the aluminum alloy melt to the following mass percentages: Mg 0.5-1.5%, Si 0.8-1.5%, Cu 0.25-0.9%, Mn 0.2-1.2%, Cr 0.05-0.5%, Fe 0.1-0.8%, Ti+V≤0.2%, Zr≤0.25%, Zn≤0.2%, Sc≤0.1%, and the balance is Al; S2. Transfer and refining: The aluminum alloy melt is kept warm for a period of time and then slag is removed. The aluminum alloy melt is then transferred to a holding furnace controlled at 700-750°C and allowed to stand for a period of time for degassing. The aluminum alloy melt is then transferred to a head box controlled at 700-750°C through a chute. S3. Plate Standing: The aluminum alloy melt in the front box is conveyed into the casting nozzle of the casting and rolling mill through a water trough for plate standing to form a solidified shell of a certain thickness on the surface of the slab. An Al-Ti-VB grain refiner is added to the water trough. The temperature of the aluminum alloy melt when it reaches the casting nozzle inlet is controlled to be no less than 40°C above the liquidus. The gap between the casting rollers in the casting and rolling mill is controlled to ensure that the thickness of the cast plate is no more than 5mm. S4. Casting and rolling: After the slab is successfully erected, start casting and rolling. The casting and rolling speed is not less than 1m / min. At the same time, turn on the water spray cooling device in the casting and rolling mill rolls to control the cooling water temperature to be no higher than 35°C. When the slab reaches a certain length, stop casting and rolling, and force the slab before coiling to cool by the low-temperature airflow flowing out of the cold air end of the vortex tube to obtain a high solid solution and high alloy aluminum alloy slab.

2. The casting and rolling method of a high solid solution high alloy aluminum alloy slab according to claim 1, characterized in that: In step S1, the alloy composition of the aluminum alloy melt is adjusted to the following mass percentages: Mg 0.9-1.3%, Si 0.9-1.2%, Cu 0.3-1.1%, Mn 0.7-1.0%, Cr 0.05-0.25%, Fe 0.4-0.7%, Ti+V≤0.2%, Zr≤0.25%, Zn≤0.2%, Sc≤0.1%, and the balance is Al.

3. The casting and rolling method of a high solid solution high alloy aluminum alloy slab according to claim 1, characterized in that: In step S2: the temperature of the front box is controlled at 710-735°C.

4. The casting and rolling method of a high solid solution high alloy aluminum alloy slab according to claim 1, characterized in that: In step S3: the gap between the casting rolls is controlled to be 1-3 mm.

5. The casting and rolling method of a high solid solution high alloy aluminum alloy slab according to claim 4, characterized in that: In step S3: the thickness of the cast plate is controlled to be 2-4 mm.

6. The method for casting and rolling a high solid solution high alloy aluminum alloy slab according to claim 5, characterized in that: In step S4: the thickness of the quenching layer in the obtained high solid solution high alloy aluminum alloy slab accounts for 15-80%, and the thickness of the quenching layer on one side is 0.3-1.1 mm.

7. The method for casting and rolling a high solid solution high alloy aluminum alloy slab according to claim 4, characterized in that: In step S3: the thickness of the cast plate is controlled at 2-3 mm.

8. The method for casting and rolling a high solid solution high alloy aluminum alloy slab according to claim 7, characterized in that: In step S4: the thickness of the quenching layer in the obtained high solid solution high alloy aluminum alloy slab accounts for 30-100%, and the thickness of the quenching layer on one side is 0.5-1 mm.

9. The method for casting and rolling a high solid solution high alloy aluminum alloy slab according to claim 1, characterized in that: In step S4: the cooling water temperature is controlled at 20-32°C, the casting speed is controlled at 1.5-3m / min, and the temperature of the low-temperature air flow flowing out of the cold air end of the vortex tube is as low as -50°C.

10. The method for casting and rolling a high solid solution high alloy aluminum alloy slab according to claim 1, characterized in that: In step S4: a pulse power supply device is set at the inflow side of the aluminum alloy melt, and the pulse power supply is turned on during the casting process, and the AC frequency is controlled to be 10-40Hz and the current density is 0.1-0.5A / mm 2 .

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