Preparation process of super heavy coiled aluminum alloy disc round rod material

Abstract

The present application relates to a kind of preparation processes of super large volume heavy aluminum alloy disc round rod stock, it includes the following processes: S1, aluminum alloy melt is obtained by using horizontal continuous casting method to be the disc round rod blank of aluminum alloy coil of target rod material diameter 2.5-3.5 times diameter;S2, the disc round rod blank of aluminum alloy coil is heated to homogenization temperature in heat cycle furnace and is kept for 6-12h, after furnace cooling to 220-280 ℃, it is discharged and air-cooled, to obtain the disc round rod blank of aluminum alloy coil of homogenization treatment;S3, the disc round rod blank of aluminum alloy coil is discharged, straightened, after online induction heating, it is sent into hot continuous rolling mill and is continuously rolled into the rod material of target diameter;Hot continuous rolling total reduction is greater than or equal to 85%;S4, is arranged into coil.The present application is more suitable for producing super large volume heavy high-strength, high-performance, difficult deformation aluminum alloy bar compared with prior art, with the characteristics of small investment, simple process, easy operation, production flexibility, high yield, low production cost etc.

Description

Technical Field

[0001] This invention belongs to the field of metal plastic processing technology, and particularly relates to a preparation process for ultra-large coiled aluminum alloy disc rods. Background Technology

[0002] High-strength aluminum alloys of the 2xxx and 7xxx series are widely used in the manufacture of fasteners, mainly bolts, screws, and rivets, due to their excellent shearing and riveting properties. With the increasing demand for high-strength, lightweight aluminum alloy fasteners in my country's aerospace, automotive, and military product manufacturing sectors, the demand for bars and wires used in the manufacture of rivets and bolts is also growing. Currently, domestic methods for preparing aluminum alloy bars and wires include continuous casting and rolling, semi-continuous ingot casting-hot extrusion, and semi-continuous ingot casting-hot continuous rolling.

[0003] While continuous casting and rolling theoretically has no weight limitations and can produce infinitely long, jointless aluminum alloy bars, this process is only suitable for some medium- and low-strength aluminum alloys. Currently, it is mainly used for large-scale production of 1xxx and a small amount of 6xxx series aluminum and aluminum alloy wire rods. Because 2xxx and 7xxx series aluminum alloys are ultra-high strength and difficult-to-deform alloys, exhibiting a narrow hot working range during deformation, continuous casting and rolling is not suitable for, or cannot be used for, the production of high-strength aluminum alloy bars and wires.

[0004] Currently, the mainstream production of 2xxx and 7xxx high-strength aluminum alloy bars is the semi-continuous ingot casting-hot extrusion process. However, due to the extremely low extrusion speed and numerous production steps (including: semi-continuous casting → ingot homogenization → ingot heating → hot extrusion → online quenching → automatic traction → sawing → tension straightening → artificial aging treatment, etc.), production efficiency cannot keep up, which to some extent limits its large-scale application. In addition, the most important point is that the "semi-continuous ingot casting-hot extrusion process" can usually only produce bars and wires with short lengths or small coil weights (the maximum coil weight is about 200Kg). Short bars and wires with small coil weights are not suitable for providing raw materials for supporting equipment / production lines for high-speed automated production of fasteners. In order to ensure the smooth operation and high efficiency of subsequent production processes, aluminum alloy bars and wires with large coil weights or even ultra-large coil weights must be used.

[0005] To address this, the industry has developed a highly efficient semi-continuous casting-hot rolling process in recent years. In this process, semi-continuous casting billets are rolled across multiple stands, with alternating passes pressing down on the width and height of the rolled piece, achieving the transformation from large-diameter billets to small-diameter bars. Compared to the semi-continuous casting-hot extrusion process, which produces shorter lengths of only a few meters, the semi-continuous casting-hot rolling process can process billets up to approximately 10 meters in length. Continuous rolling can then yield high-strength aluminum alloy bars and wires with larger coil weights (up to 300 kg). In actual production, to improve the dendrite segregation of large-diameter semi-continuous casting billets and enhance alloy performance, the equipment costs required for hot rolling are substantial, including large heating furnaces and large hot roughing, intermediate, and finishing mills. Furthermore, the temperature drop (temperature difference) during the hot rolling process significantly affects the performance and uniformity of the aluminum alloy bars and wires. Currently, there are few reports of using hot rolling to produce high-performance, difficult-to-deform aluminum alloy bars. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] In view of the characteristics of current aluminum alloy bar and wire production technology and the many limitations of existing technologies, this invention proposes a preparation process for ultra-large coil weight aluminum alloy disc rods. Compared with existing technologies, the process is more suitable for producing ultra-large coil weight, high strength, high performance, and difficult-to-deform aluminum alloy bars. It has the characteristics of low investment, simple process, convenient operation, flexible production, high yield, and low production cost.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0010] In a first aspect, the present invention provides a process for preparing ultra-large coiled aluminum alloy disc rods, comprising the following steps:

[0011] S1. Horizontal continuous casting of alloy disc rod billets: Aluminum alloy disc rod billets with a diameter of 2.5-3.5 times the target rod diameter are obtained by horizontal continuous casting of aluminum alloy melt.

[0012] S2. Homogenization treatment: The coiled aluminum alloy disc billet is heated to the homogenization temperature in a hot circulating furnace and held for 6-12 hours. Then it is cooled in the furnace to 220-280℃ and then removed from the furnace and air-cooled to obtain the homogenized coiled aluminum alloy disc billet.

[0013] Specifically, when the aluminum alloy is a 2XXX series aluminum alloy, the homogenization temperature is 460-500℃; when the aluminum alloy is a 5XXX series aluminum alloy, the homogenization temperature is 500-550℃; when the aluminum alloy is a 6XXX series aluminum alloy, the homogenization temperature is 520-560℃; and when the aluminum alloy is a 7XXX series aluminum alloy, the homogenization temperature is 460-490℃.

[0014] S3. Online induction heating and hot continuous rolling: The coiled aluminum alloy disc billet is fed into a hot continuous rolling mill for continuous rolling into a rod of the target diameter after being fed into the mill, straightened, and induction heated online; wherein the total reduction of hot continuous rolling is ≥85%; S4. Coiling.

[0015] According to a preferred embodiment of the present invention, in S1, the aluminum alloy melt is used to obtain a coiled aluminum alloy disc rod blank with a diameter of 25-35mm by a horizontal continuous casting method.

[0016] According to a preferred embodiment of the present invention, in S1, the aluminum alloy melt is obtained by batching and melting according to the chemical element composition of 7xxx series high-strength aluminum alloy.

[0017] According to a preferred embodiment of the present invention, in S2, the coiled aluminum alloy disc billet is heated to 470-480°C in a hot circulating furnace and held for 8-10 hours, then cooled to 250-260°C in the furnace before being removed from the furnace and air-cooled.

[0018] According to a preferred embodiment of the present invention, in S3, the target diameter is 8-12 mm.

[0019] According to a preferred embodiment of the present invention, in S3, the starting rolling temperature of the hot strip mill is related to the type of aluminum alloy. When the aluminum alloy is a 7xxx series high-strength aluminum alloy, the starting rolling temperature of the hot strip mill is 430-470℃; when the aluminum alloy is a 6xxx series high-strength aluminum alloy, the starting rolling temperature of the hot strip mill is 480-530℃; when the aluminum alloy is a 2XXX series alloy, the starting rolling temperature of the hot strip mill is 430-480℃; and when the aluminum alloy is a 5XXX series alloy, the starting rolling temperature of the hot strip mill is 450-510℃.

[0020] According to a preferred embodiment of the present invention, in S3, the aluminum alloy is a 7xxx series high-strength aluminum alloy, the hot rolling mill opening temperature is 450-460℃, and the total reduction is ≥85%.

[0021] According to a preferred embodiment of the present invention, in S4, the weight of a single roll of bar stock is ≥1000Kg.

[0022] According to a preferred embodiment of the present invention, in S1, the pouring temperature of the horizontal continuous casting is 680-690°C, and the casting speed is 550-620 mm / min.

[0023] Secondly, the present invention provides an ultra-large coiled aluminum alloy disc rod material, which is prepared using the preparation process of any of the above embodiments.

[0024] (III) Beneficial Effects

[0025] (1) The present invention uses horizontal continuous casting to produce small-diameter aluminum alloy disc rod blanks, and then the small-diameter rod blanks are homogenized, induction heated and hot rolled. Compared with ingots and cast rod blanks, small-diameter rod blanks have the advantages of fast solidification speed, less internal oxide inclusions and low gas content, uniform structure and well-developed dendrites, small interdendritic segregation and large solid solubility of alloying elements. It can effectively shorten the homogenization treatment time of alloy ingots and improve the processing performance and mechanical properties of alloys.

[0026] (2) Horizontal continuous casting can continuously cast small-diameter coiled aluminum alloy rod blanks with large coil weights (over 1000 kg per coil). After hot rolling (total hot rolling deformation not less than 85%), high-performance aluminum alloy rod blanks with a single coil weight ≥ 1000 kg can be obtained. Compared with hot extrusion, this invention generally adopts a combination of small-diameter cast rod blanks and continuous hot rolling process, which not only has a faster processing speed, fewer processes, and higher production efficiency, but also produces rod blanks with a large single coil weight, which can provide raw materials for supporting equipment / production lines for high-speed automated production of fasteners (bolts, screws, rivets, etc.).

[0027] (3) The preparation process of the present invention requires little investment. Apart from the hot circulating furnace needing to have the ability to homogenize aluminum alloy disc billets with large coil weights, it does not require the purchase of large hot roughing, intermediate rolling, and finishing rolling mills. Furthermore, since the billets obtained by horizontal continuous casting are small-diameter billets with little dendrite segregation, and combined with the online induction heating process, the temperature distribution of the billets is uniform during hot continuous rolling, effectively avoiding the problem of uneven bar and wire properties caused by uneven temperature distribution during the rolling process.

[0028] (4) The preparation process of the present invention is particularly suitable for producing high-strength, high-performance, and difficult-to-deform aluminum alloy disc rods with ultra-large coil weight (single coil weight ≥ 1000Kg), such as producing 7xxx high-strength aluminum alloy rods with ultra-large coil weight, and can also produce 1xxx and a small amount of 6xxx and other lower strength ultra-large coil weight aluminum and aluminum alloy wire rods. Detailed Implementation

[0029] In view of the characteristics of current aluminum alloy bar and wire production technology and the many limitations of existing technologies, this invention provides a process for preparing ultra-large coil weight aluminum alloy disc rods, including the following steps:

[0030] S1. Horizontal continuous casting of alloy disc rod blanks: The aluminum alloy melt is used to obtain coiled aluminum alloy disc rod blanks with a diameter of 2.5-3.5 times the target rod diameter by horizontal continuous casting.

[0031] Preferably, the aluminum alloy melt is obtained by batching and heating according to the chemical element composition of 7xxx aluminum alloy materials. When the target diameter of the aluminum alloy disc rod product is 8-12mm, a coiled aluminum alloy disc rod blank with a diameter of 25-35mm can be obtained first by horizontal continuous casting, and the rod blank can be used as raw material for subsequent processing.

[0032] S2. Homogenization treatment: The coiled aluminum alloy rod billet is heated to the homogenization temperature in a hot circulating furnace and held for 6-12 hours. Then it is cooled in the furnace to 220-280℃ and air-cooled to obtain the homogenized coiled aluminum alloy rod billet. The homogenization temperature of 2XXX series aluminum alloy is 460-500℃, the homogenization temperature of 5XXX series aluminum alloy is 500-550℃, the homogenization temperature of 6XXX series aluminum alloy is 520-560℃, and the homogenization temperature of 7XXX series aluminum alloy is 460-490℃.

[0033] Trial production experiments were conducted on the four types of aluminum alloy rods. The results showed that the homogenization temperature should be within the above range. Otherwise, if the homogenization temperature is too high, overheating will occur, resulting in poor alloy performance. If the homogenization temperature is too low, the coarse secondary phase in the alloy cannot be dissolved, and the solid solution effect cannot be achieved.

[0034] Regarding the homogenization holding time: Typically, to completely eliminate the coarse secondary phases generated during casting, solution treatment involves using high temperatures and maintaining the treatment for a long time to ensure complete dissolution and improve the alloy's machinability. Therefore, semi-continuous casting produces large-diameter billets with slow cooling rates, resulting in coarser secondary phases and requiring sufficiently long holding times, typically 24-48 hours. Conversely, this invention uses horizontal continuous casting to produce small-diameter billets with very rapid cooling rates, resulting in smaller, more easily dissolved secondary phases. Therefore, the homogenization time can be shortened to 6-12 hours. Excessive holding time is economically unfeasible, while insufficient holding time fails to achieve complete dissolution.

[0035] After homogenization and heat treatment, the billet is first cooled in the furnace to 220-280℃ and then air-cooled. This ensures that the horizontally continuously cast billet has good plasticity, facilitating subsequent hot rolling processes such as wire feeding, straightening, and hot rolling performance. If it is directly cooled after exiting the furnace, the small diameter and excessively rapid cooling rate may lead to solid solution strengthening, increasing the billet's strength but reducing its plasticity, which is detrimental to subsequent processing steps. Exiting the billet from 220-280℃ and then air-cooling it to room temperature avoids complete solid solution formation, allowing only a small amount of precipitate to escape. Therefore, while the billet's strength is slightly reduced, its plasticity is improved, providing better processing conditions for subsequent wire feeding, straightening, and hot rolling.

[0036] When the aluminum alloy disc / rod billet is made of 7XXX series aluminum alloy, it is preferable to heat the aluminum alloy disc / rod billet to 470-480℃ in a hot circulating furnace and hold it for 8-10 hours, then cool it in the furnace to 250-260℃ before taking it out of the furnace and air cooling.

[0037] S3. Online induction heating and hot continuous rolling: The coiled aluminum alloy disc billet is fed into a hot continuous rolling mill for continuous rolling into a rod with a diameter of 8-12mm after being fed into the coil, straightened, and induction heated online. The total reduction is controlled to be ≥85%.

[0038] The initial rolling temperature of a hot strip mill is related to the type of aluminum alloy. For high-strength 7XXX series alloys, an initial rolling temperature of 430-470℃ (more preferably 450-460℃) provides good plasticity. If the initial rolling temperature is too high, deformation heat will be generated during high-speed rolling, increasing the cumulative deformation temperature and potentially leading to hot cracking. Conversely, if the initial rolling temperature is too low, it will increase the alloy's strength but decrease its plasticity, which is detrimental to rolling deformation. For other aluminum alloys, such as 6XXX series alloys, the initial rolling temperature can be increased to 480-530℃, 2XXX series alloys to 430-480℃, and 5XXX series alloys to 450-510℃.

[0039] Trial production experiments were conducted on four types of aluminum alloy bars. The results showed that, for the four difficult-to-machine alloy systems of 2XXX, 5XXX, 6XXX, and 7XXX, only at the aforementioned rolling temperatures could good plasticity and processing performance be achieved while avoiding hot cracking.

[0040] The material processed in this step is a cast small-diameter aluminum alloy disc billet with well-developed dendrites. Experimental studies have found that when the total reduction is ≥85%, the grain size of the hot-rolled alloy rod is already very fine, reaching 30-50 micrometers. Therefore, the aluminum alloy rod of this invention has good alloy properties, which has been proven in subsequent embodiments.

[0041] S4. Roll up; single roll weight ≥ 1000Kg.

[0042] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to specific embodiments.

[0043] Example 1

[0044] This embodiment uses a typical manufacturing process for high-strength 7075 aluminum alloy coiled rods as an example. Based on the standard chemical composition of 7075 aluminum alloy, 99.7% aluminum ingots, zinc ingots, and magnesium ingots, along with Al-10Cu, Al-5Mn, Al-5Ti, and Al-5Cr master alloys, are used. The aluminum alloy is prepared according to the designed weight ratio and feeding rules, and melted in a dual 1000kg capacity gas-fired melting furnace. After degassing and slag removal refining treatment, the melt is sampled using a direct-reading spectroscopic method for chemical composition analysis. The measured composition is shown in Table 1.

[0045] Table 1: Main chemical composition of 7075 aluminum alloy (weight percentage, %)

[0046] standard ≤0.40 ≤0.50 1.2-2.0 ≤0.3 2.1-2.9 0.18-0.28 5.1-6.1 ≤0.2 Actual measurement 0.051 0.211 1.38 0.003 2.54 0.212 5.51 0.053

[0047] After heat preservation, multi-stage filtration, and composite degassing and slag removal, the aluminum alloy coiled rods are cast into 35mm diameter coiled rods using an 8-strand horizontal continuous casting process. The pouring temperature is 680-690℃, and the casting speed is 550mm / min. The aluminum alloy coiled rods obtained by the horizontal continuous casting method are heated to 485℃ in a 110KW box-type hot circulating resistance furnace and held for 10 hours. After being cooled to 260℃ in the furnace, they are air-cooled for homogenization treatment. The homogenized aluminum alloy coiled rods are then fed into a hot continuous rolling mill for continuous rolling into 10mm diameter coiled rods. The initial rolling temperature is 470℃, and the total reduction should be guaranteed to be 91.8%. The rods are then rolled into 8 coils, each weighing between 1016-1127Kg. Samples were taken from the head and tail of the hot-rolled bar and subjected to annealing treatment of holding at 415℃ for 2 hours and then air cooling after removal from the furnace, and water quenching at 475℃ for 1 hour followed by T6 heat treatment at 120℃ for 24 hours. The average values ​​of the annealed and T6 mechanical properties of the 7075 aluminum alloy bar are shown in Table 2.

[0048] Table 2: Test results of mechanical properties of 7075 aluminum alloy coils in Example 1

[0049]

[0050]

[0051] As shown in Table 2, the 7075 representative high-strength aluminum alloy coils produced using the high-strength aluminum alloy coil preparation process of this invention exhibit excellent mechanical properties, exceeding the requirements of currently published standards, after standard annealing and T6 heat treatment on samples taken from the head and tail of coils weighing over a ton. Furthermore, after stretching and annealing, the above alloy coils, when cold-headed into screws and shoe nails, ensure good tooth and nail formation with excellent dimensional accuracy and surface quality, achieving a yield rate of over 90%.

[0052] Example 2

[0053] This embodiment is used to produce 7075 aluminum alloy disc rods. The only difference between this embodiment and Example 1 is that the 7075 aluminum alloy disc rod blank obtained by the horizontal continuous casting method is heated to 460°C and held for 6 hours in a 110KW box-type thermal circulation resistance furnace, then cooled to 260°C in the furnace and air-cooled for homogenization. Other production conditions are the same as in Example 1.

[0054] Example 3

[0055] This embodiment is used to produce 7075 aluminum alloy disc rods. The only difference between this embodiment and Example 1 is that the 7075 aluminum alloy disc rod blank obtained by the horizontal continuous casting method is heated to 480°C and held for 8 hours in a 110KW box-type thermal circulation resistance furnace, then cooled to 260°C in the furnace and air-cooled for homogenization. Other production conditions are the same as in Example 1.

[0056] Example 4

[0057] This embodiment is used to produce 7075 aluminum alloy disc rods. The only difference between this embodiment and Example 1 is that the 7075 aluminum alloy disc rod blank obtained by the horizontal continuous casting method is heated to 470°C and held for 10 hours in a 110KW box-type thermal circulation resistance furnace, then cooled to 260°C in the furnace and air-cooled for homogenization. Other production conditions are the same as in Example 1.

[0058] Samples were taken from the head and tail of the hot-rolled bar material coiled in Examples 2-4. The samples were subjected to annealing treatment of holding at 415℃ for 2 hours and then air cooling, and water quenching at 475℃ for 1 hour followed by T6 heat treatment at 120℃ for 24 hours. The average values ​​of the annealed and T6 mechanical properties of the 7075 aluminum alloy bar material are shown in Table 3.

[0059] Table 3

[0060]

[0061] As can be seen from Examples 1-4, the better conditions for homogenizing the 7075 aluminum alloy disc rod blanks obtained by the horizontal continuous casting method are: heating to 470-480℃ in a hot circulating furnace and holding for 8-10 hours, then cooling to 250-260℃ in the furnace and air cooling. The aluminum alloy rods obtained under these process conditions can achieve both good elongation and high strength.

[0062] Example 5

[0063] This embodiment is used to produce 7075 aluminum alloy coiled rods. The only difference between this embodiment and Example 1 is that when continuously rolling the coiled rods to a diameter of 10mm using a hot strip mill, the initial rolling temperature is 430℃, and the total reduction should be guaranteed to be 91.8%. Other production conditions are the same as in Example 1.

[0064] Example 6

[0065] This embodiment is used to produce 7075 aluminum alloy coiled rods. The only difference between this embodiment and the one in embodiment 1 is that when the coiled rods are continuously rolled into 10mm diameter coiled rods using a hot rolling mill, the initial rolling temperature is 460℃ and the total reduction should be 91.8%.

[0066] Samples were taken from the head and tail of the hot-rolled bar material from Examples 5-6 and subjected to annealing treatment of holding at 415℃ for 2 hours and then air cooling after removal from the furnace, and water quenching at 475℃ for 1 hour followed by T6 heat treatment at 120℃ for 24 hours. The average values ​​of the annealed and T6 mechanical properties of the 7075 aluminum alloy bar material are shown in Table 4.

[0067] Table 4

[0068]

[0069] As can be seen from Examples 1 and 5-6, the optimal conditions for hot continuous rolling of aluminum alloy billets are: an initial rolling temperature of 450-460℃ and a total reduction of ≥85%; aluminum alloy billets obtained under these process conditions can achieve both good elongation and high strength.

[0070] Example 7

[0071] In this embodiment, based on the 2024 standard chemical composition of aluminum alloy, 99.7% aluminum ingots and magnesium ingots, as well as Al-10Cu, Al-5Mn and Al-5Ti master alloys, were used to prepare the aluminum alloy according to the designed weight ratio and feeding rules. The alloy was melted in a dual 1000Kg capacity gas-fired melting furnace. After degassing and slag removal refining treatment, the melt was sampled and chemically analyzed using a direct-reading spectral method. The measured composition is shown in Table 5.

[0072] Table 5: Main Chemical Composition of 2024 Aluminum Alloy (Weight Percentage, %)

[0073] standard ≤0.5 ≤0.5 3.8-4.9 0.3-0.9 1.2-1.8 ≤0.1 ≤0.25 ≤0.15 Actual measurement 0.098 0.192 4.26 0.636 1.58 0.017 0.052 0.079

[0074] After heat preservation, multi-stage filtration, and composite degassing and slag removal, the aluminum alloy coiled rods are cast into 35mm diameter coiled rods using an 8-strand horizontal continuous casting process. The pouring temperature is 690-700℃, and the casting speed is 650mm / min. The aluminum alloy coiled rods obtained by the horizontal continuous casting method are heated to 485℃ and held for 10 hours in a 110KW box-type hot circulating resistance furnace. After being cooled to 260℃ in the furnace, they are then air-cooled for homogenization treatment. The homogenized aluminum alloy coiled rods are then fed, straightened, and induction heated online before being continuously rolled into 10mm diameter coiled rods on a hot continuous rolling mill. The initial rolling temperature is 470℃, and the total reduction should be guaranteed to be 91.8%. The rods are then rolled into 8 coils, each weighing between 1008-1123Kg. Samples were taken from the head and tail of the hot-rolled bar and subjected to annealing treatment of holding at 415℃ for 2 hours and then air cooling after removal from the furnace, and water quenching at 490℃ for 1 hour followed by T6 heat treatment at 190℃ for 12 hours. The average values ​​of the annealed and T6 mechanical properties of the 2024 aluminum alloy bar are shown in Table 6.

[0075] Table 6: Test results of mechanical properties of 2024 aluminum alloy coils in Example 7

[0076]

[0077] As can be seen from Table 6, the representative high-strength aluminum alloy coils of 2024 produced by the high-strength aluminum alloy coil preparation process of the present invention, after standard annealing and T6 heat treatment of the head and tail of the coils of ton size and above, were found to have excellent mechanical properties, exceeding the requirements of the currently published standards.

[0078] Example 8

[0079] Using 99.7% aluminum ingots, fast-melting Si, magnesium ingots, and Al-5Cr and Al-10Cu master alloys, the weight ratio of each alloy added was calculated based on the chemical composition range of 6061 aluminum alloy. The materials were prepared according to this ratio, and after melting, refining, holding and online filtration in a dual 1000Kg capacity gas-fired melting furnace, samples were taken for alloy chemical composition analysis, as shown in Table 7.

[0080] Table 7. Main chemical composition (weight percentage, %) of the 6061 aluminum alloy of this invention

[0081] standard 0.40-0.8 ≤0.7 0.15-0.40 ≤0.15 0.8-1.2 0.04-0.35 — ≤0.25 Actual measurement 0.623 0.169 0.311 0.021 0.932 0.243 0.021 0.035

[0082] Aluminum alloy rods with a diameter of 35mm are continuously cast using a horizontal continuous casting method. The continuous casting temperature is controlled at 710-720℃, and the casting speed is set at 1000mm / min. The aluminum alloy rods obtained by the horizontal continuous casting method are heated to 540℃ and held for 10 hours in a 110KW box-type hot circulating resistance furnace. After being cooled to 260℃ in the furnace, they are air-cooled for homogenization treatment. The aluminum alloy rods obtained after homogenization treatment are fed, straightened, and induction heated online before being sent to a hot continuous rolling mill for continuous rolling into rods with a diameter of 10mm. The initial rolling temperature is 520℃, and the total reduction should be guaranteed to be 91.8%. The rods are then rolled into 8 coils with a single coil weight of 1018-1201Kg. Samples were taken from the head and tail of the hot-rolled bar and subjected to annealing treatment of holding at 415℃ for 2 hours and then air cooling after removal from the furnace, and water quenching at 540℃ for 1 hour followed by T6 heat treatment at 175℃ for 8 hours. The average values ​​of the annealed and T6 mechanical properties of the 6061 aluminum alloy bar are shown in Table 8.

[0083] Table 8: Test results of mechanical properties of 6061 aluminum alloy coils in Example 8

[0084]

[0085] As can be seen from Table 8, the 6061 representative high-strength aluminum alloy coil produced by the high-strength aluminum alloy disc rod preparation process of the present invention, after sampling the head and tail of the coils of ton size and above and performing standard annealing and T6 heat treatment, was found to have excellent mechanical properties, exceeding the requirements of the currently published standards.

[0086] In summary, the manufacturing process of this invention requires minimal investment, needing only one hot finishing mill to directly roll horizontally continuously cast small-diameter coiled rods into high-strength aluminum alloy large-coil weight bars of commonly used specifications (diameter 8-12mm). This provides a new near-forming production process for the research, development, and production of ultra-large coil weight (ton-level products) aluminum alloy coiled rods from 6-series, 5-series, and / or 2-series and / or 7-series aluminum alloys. Furthermore, it features low investment, simple process, convenient operation, flexible production, high yield, and low production cost.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing ultra-large coiled aluminum alloy disc rods used as raw materials for fastener production, characterized in that, The process includes the following steps: S1. Horizontal continuous casting of alloy disc rod blanks: Aluminum alloy melt is used to obtain coiled aluminum alloy disc rod blanks with a diameter of 25-35mm by horizontal continuous casting. S2. Homogenization treatment: The coiled aluminum alloy disc billet is heated to the homogenization temperature in a hot circulating furnace and held for 6-12 hours. Then it is cooled in the furnace to 220-280℃ and then removed from the furnace and air-cooled to obtain the homogenized coiled aluminum alloy disc billet. Wherein, when the aluminum alloy is a 2XXX series aluminum alloy, the homogenization temperature is 460-500℃; when the aluminum alloy is a 6XXX series aluminum alloy, the homogenization temperature is 520-560℃; when the aluminum alloy is a 7XXX series aluminum alloy, the homogenization temperature is 460-490℃. S3. Online Induction Heating and Hot Continuous Rolling: The coiled aluminum alloy disc billet is fed into a hot continuous rolling mill after being straightened, induction heated online, and continuously rolled into a rod with a target diameter of 8-12mm; wherein the total reduction in hot continuous rolling is ≥85%; When the aluminum alloy is a 7xxx series high-strength aluminum alloy, the starting rolling temperature of the hot strip mill is 430-470℃; when the aluminum alloy is a 6xxx series high-strength aluminum alloy, the starting rolling temperature of the hot strip mill is 480-530℃; when the aluminum alloy is a 2XXX series alloy, the starting rolling temperature of the hot strip mill is 430-480℃. S4. Collect and roll up.

2. The preparation process according to claim 1, characterized in that, In S1, the aluminum alloy melt is obtained by batching and melting according to the chemical element composition of 7xxx series high-strength aluminum alloy.

3. The preparation process according to claim 1, characterized in that, In S2, when the aluminum alloy is a 7XXX series aluminum alloy, the coiled aluminum alloy disc billet is heated to 470-480℃ in a hot circulating furnace and held for 8-10 hours. After being cooled to 250-260℃ in the furnace, it is taken out of the furnace and air-cooled.

4. The preparation process according to claim 1, characterized in that, In S3, the aluminum alloy is a 7xxx series high-strength aluminum alloy, the hot rolling mill opening temperature is 450-460℃, and the total reduction is ≥85%.

5. The preparation process according to claim 1, characterized in that, In S4, the weight of a single coil of bar stock is ≥1000Kg.

6. An ultra-large coiled aluminum alloy disc rod material for use as a raw material in fastener production, which is prepared by the preparation process described in any one of claims 1-5.

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