Hot rolling method of 7000 series aluminum alloy wire bar

Abstract

The invention discloses a hot rolling method for 7000 series aluminum alloy wires and bars, and relates to the technical field of aluminum alloy machining. The invention aims to solve the problems that the production efficiency of the existing 7000 series aluminum alloy wire rod is low, the weight of a single produced wire rod is small, the structure uniformity is poor, and the prepared wire rod cracks when a rivet is upset. According to the hot rolling method for the 7000 series aluminum alloy wire and bar, 98% of large-deformation reducing can be achieved, and cracking is avoided; compared with a wire rod prepared by an extrusion and drawing process, the weight of the hot-rolled wire prepared by the method can reach 300 kilograms; and meanwhile, the preparation efficiency is high, and production of one coil of 300 kilograms of wire rods or more than 100 bars can be completed within one hour. According to the hot rolling method for the 7000 series aluminum alloy wire bar, the 7000 series aluminum alloy wire bar can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy processing, and in particular to a hot rolling method for 7000 series aluminum alloy wire rods. Background Art

[0002] Steel wire rods are often used in industry. With the demand for lightweight and high strength in aviation, aerospace, shipbuilding, rail transportation and other fields, more and more products using aluminum instead of steel have emerged. Aluminum alloy wire rods have also gained huge demand and are used to prepare aluminum alloy fasteners, aluminum alloy welding wires and conductors.

[0003] Domestically, aluminum alloy wire rods are mostly prepared using the "extrusion + drawing" process. The process is to first prepare aluminum alloy round cast rods through semi-continuous casting technology, and then use an extruder to extrude the cast rods into aluminum rods with a diameter of about 10 mm after sawing them to a fixed length. Then, the wire coils are obtained through multiple drawing passes. This method has a wide adaptability and can basically produce all series of deformed aluminum alloys. However, due to the limitations of the extrusion barrel length and extrusion ratio, as well as the length and weight of a single jointless coil, it cannot meet the needs of modern automatic fastener production equipment and the needs of continuous wire feeding of welding wire. In addition, due to the uneven metal flow and the instability of the extrusion temperature during the extrusion process, the products have problems with uneven organizational properties.

[0004] In order to achieve continuity, a process for continuous casting and rolling of aluminum alloy wire rods has been developed. The process is to produce trapezoidal continuous casting billets through wheel-type continuous casting, and then hot-roll them to bars of about 10 mm. The products of this process are not limited by weight, and theoretically, it is possible to produce unlimited length of jointless aluminum. However, this process can only produce medium and low strength aluminum alloys. Since the crystallization zone of the wheel-type crystallizer is long and arc-shaped, alloys with wide liquid-solid two-phase zones are prone to casting cracks. Due to the limitations of the process characteristics, it is impossible to produce high-strength aluminum alloy discs with a tensile strength of more than 400MPa. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of low production efficiency of existing 7000 series aluminum alloy wire rods, small weight of a single wire rod, poor uniformity of structure, and cracking of the prepared wire rod during upsetting rivets, and to provide a hot rolling method for 7000 series aluminum alloy wire rods.

[0006] A hot rolling method for 7000 series aluminum alloy wire rod is carried out according to the following steps:

[0007] Step S1: Car skin;

[0008] Carrying the cast aluminum alloy ingot into a car body to obtain a car body aluminum alloy ingot;

[0009] Step S2: keeping warm;

[0010] The aluminum alloy ingot after the car body obtained in step S1 is placed in a box-type heating furnace, heated to 400° C. to 470° C., and kept at 400° C. to 470° C. for 1 h to 3 h to obtain the aluminum alloy ingot after keeping warm;

[0011] Step S3: hot rolling;

[0012] The aluminum alloy ingot obtained in step S2 is sequentially hot-rolled by three sets of flat vertical roll mills, eight Y-type stand mills and four straight-diameter Y-type stand mills to obtain aluminum alloy wire rods;

[0013] Step S4: hot finishing rolling;

[0014] The aluminum alloy wire rod obtained in step S3 is uncoiled, and then the rod is heated to 400°C to 470°C by an online heating device. After the heating is completed, it is first reduced in diameter by 4 to 7 Y-type stand rolling mill groups, and then rounded by 3 straightening Y-type stand rolling mill groups to obtain 7000 series aluminum alloy wire rods. The 7000 series aluminum alloy wire rods contain the following elements and mass fractions: Cu is 1.6 to 2.6%, Mg is 1.6 to 2.9%, and Zn is 6.0 to 10.0%, and the balance is Al.

[0015] Principle of the present invention:

[0016] Compared with traditional extruded wire billets, the hot rolling production method can achieve large deformation of long ingots and produce single wire billets with a weight of more than 300kg. However, extrusion is limited by the length of the extrusion barrel and can only produce single wire billets with a weight of 7kg, which improves the production efficiency of subsequent wire rods and increases the weight of a single finished wire to more than 200kg. During the extrusion process, the ingot is affected by circumferential force and longitudinal force. When the deformation is too large, it is easy to "stuck car", that is, the metal accumulates in the extrusion barrel and cannot be formed. Hot rolling is only subject to longitudinal force, so it can be rolled into shape with a large deformation. Therefore, the deformation of extrusion molding is only about 70%, and the deformation of hot rolling molding can reach 98%. The large deformation of hot rolling makes the grains small and uniform, the difference between the core and the surface is small, and the uniformity of the organization is good, which effectively solves the problem of cracking of wire when upsetting rivets.

[0017] Beneficial effects of the present invention:

[0018] (1) The hot rolling method of the 7000 series aluminum alloy wire rod of the present invention can achieve The preparation of standard wire rods, if further cold drawn, can be prepared Compared with the "continuous casting and rolling" process, the aluminum alloy wire rod produced by this method has a more uniform structure. When preparing fasteners, it can solve the problem of cracking during the cold heading of rivets, threading of bolts and closing of nuts. At the same time, the aluminum alloy wire produced by this method has a better melt quality, and can achieve a hydrogen content of ≤0.12ml / 100gAl. After being prepared into welding wire, it can effectively optimize the porosity problem caused by welding.

[0019] (2) The hot rolling method of the 7000 series aluminum alloy wire rod of the present invention can achieve a large deformation diameter change of 98% without cracking; compared with the wire rod prepared by the "extrusion + drawing" process, the weight of the hot-rolled wire prepared by this method can reach 300 kg; at the same time, the preparation efficiency is high, and the production of 1 coil of 300 kg wire or more than 100 rods can be completed within 1 hour.

[0020] (3) The present invention explores the application of hot rolling technology on 7000 series aluminum alloys, and overcomes the continuous rolling technology of high-strength aluminum alloy wire and bar materials, which can meet the urgent needs of modern high-quality aluminum alloy wire and bar materials.

[0021] The invention can obtain a hot rolling method for 7000 series aluminum alloy wire rods. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The microstructure diagram of the 7000 series aluminum alloy wire rod prepared in Example 1 is shown;

[0023] Figure 2 A physical picture showing the 7000 series aluminum alloy round wire prepared by the present invention;

[0024] Figure 3 A physical picture showing the 7000 series aluminum alloy straight bar prepared by the present invention. DETAILED DESCRIPTION

[0025] Specific implementation method 1: In this implementation method, a hot rolling method of a 7000 series aluminum alloy wire rod is carried out according to the following steps:

[0026] Step S1: Car skin;

[0027] Carrying the cast aluminum alloy ingot into a car body to obtain a car body aluminum alloy ingot;

[0028] Step S2: keeping warm;

[0029] The aluminum alloy ingot after the car body obtained in step S1 is placed in a box-type heating furnace, heated to 400° C. to 470° C., and kept at 400° C. to 470° C. for 1 h to 3 h to obtain the aluminum alloy ingot after keeping warm;

[0030] Step S3: hot rolling;

[0031] The aluminum alloy ingot obtained in step S2 is sequentially hot-rolled by three sets of flat vertical roll mills, eight Y-type stand mills and four straight-diameter Y-type stand mills to obtain aluminum alloy wire rods;

[0032] Step S4: hot finishing rolling;

[0033] The aluminum alloy wire rod obtained in step S3 is uncoiled, and then the rod is heated to 400°C to 470°C by an online heating device. After the heating is completed, it is first reduced in diameter by 4 to 7 Y-type stand rolling mill groups, and then rounded by 3 straightening Y-type stand rolling mill groups to obtain 7000 series aluminum alloy wire rods. The 7000 series aluminum alloy wire rods contain the following elements and mass fractions: Cu is 1.6 to 2.6%, Mg is 1.6 to 2.9%, and Zn is 6.0 to 10.0%, and the balance is Al.

[0034] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the specifications of the aluminum alloy ingot after casting described in step S1 are

[0035] The other steps are the same as those in the first specific implementation.

[0036] Specific implementation method three: The difference between this implementation method and specific implementation method one or two is that in step S1, the curvature of the aluminum alloy ingot after the car body is less than 2 mm per meter of the ingot.

[0037] The other steps are the same as those in the first or second embodiment.

[0038] Specific implementation method 4: The difference between this implementation method and specific implementation methods 1 to 3 is that the line speed at the outlet of the wire rod during the hot rolling process in step S3 is 80 to 160 m / min.

[0039] The other steps are the same as those in Specific Embodiments 1 to 3.

[0040] Specific implementation mode five: The difference between this implementation mode and specific implementation modes one to four is that in step S3, each group of flat vertical roller mills is composed of 2 pairs of rollers, and the 2 pairs of rollers are composed of upper and lower rollers and left and right rollers. The upper and lower rollers and the left and right rollers are all semicircular rollers, wherein the arc surfaces of the upper and lower rollers are close to but not in contact with each other, and the arc surfaces of the left and right rollers are close to but not in contact with each other. Specifically, the aluminum alloy ingot is first flattened by the arc surfaces of the upper and lower rollers in front, and then the flattened aluminum alloy ingot is rounded by the arc surfaces of the left and right rollers in the rear.

[0041] The other steps are the same as those in Specific Embodiments 1 to 4.

[0042] Specific implementation method six: The difference between this implementation method and specific implementation methods one to five is that in step S3, the diameter of the rolled ring of each Y-type stand rolling mill group is 370-500 mm, and the diameter of the rolled ring of each full-diameter Y-type stand rolling mill group is 200-300 mm.

[0043] The other steps are the same as those in Specific Embodiments 1 to 5.

[0044] Specific embodiment 7: The difference between this embodiment and specific embodiments 1 to 6 is that the specification of the aluminum alloy wire rod described in step S3 is

[0045] The other steps are the same as those in Specific Embodiments 1 to 6.

[0046] Specific implementation eight: The difference between this implementation and specific implementations one to seven is that in step S4, the diameter of the rolled ring of each Y-type stand rolling mill group is 370-500 mm, and the diameter of the rolled ring of each full-diameter Y-type stand rolling mill group is 200-300 mm.

[0047] The other steps are the same as those in Specific Embodiments 1 to 7.

[0048] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the specification of the 7000 series aluminum alloy wire rod described in step S4 is

[0049] The other steps are the same as those in Specific Embodiments 1 to 8.

[0050] Specific embodiment ten: The present embodiment is different from specific embodiments one to nine in that the total deformation of the 7000 series aluminum alloy wire rod described in step S4 is above 98%.

[0051] The other steps are the same as those in Specific Embodiments 1 to 9.

[0052] The following examples are used to verify the beneficial effects of the present invention:

[0053] Embodiment 1: A hot rolling method for 7000 series aluminum alloy wire rod is carried out according to the following steps:

[0054] Step S1: Car skin;

[0055] The casting specifications are The aluminum alloy ingot is subjected to car skinning, the purpose of which is to remove the oxide layer on the surface of the ingot and ensure that the curvature of the ingot per meter is less than 2mm, so as to obtain the aluminum alloy ingot after car skinning;

[0056] The length of the aluminum alloy ingot is 6000 mm, and the curvature of the ingot per meter is less than 2 mm;

[0057] Step S2: keeping warm;

[0058] The aluminum alloy ingot after the car body obtained in step S1 is placed in a box-type heating furnace, heated to 440° C., and kept at 440° C. for 1 hour to obtain the aluminum alloy ingot after keeping the temperature, and then hot continuous rolling is started after the ingot is taken out of the furnace;

[0059] Step S3: hot rolling;

[0060] The aluminum alloy ingot after insulation obtained in step S2 is first passed through 3 groups of flat vertical roller mills, each group of flat vertical roller mills consists of 2 pairs of rollers, the 2 pairs of rollers consist of upper and lower rollers and left and right rollers, the upper and lower rollers and the left and right rollers are all semicircular rollers, wherein the arc surfaces of the upper and lower rollers are close to but not in contact with each other, and the arc surfaces of the left and right rollers are close to but not in contact with each other, specifically, the aluminum alloy ingot is first flattened by the arc surfaces of the upper and lower rollers in front, and then the flattened aluminum alloy ingot is rounded by the arc surfaces of the left and right rollers in the back; then, large-size diameter reduction is achieved by 8 Y-type frame rolling mills, and then the wire rod is rounded by 4 straightening Y-type frame rolling mills, and the specification is obtained. Aluminum alloy wire and rod;

[0061] In step S3, each Y-shaped roller stand is composed of a rolling ring and a jacket, and the diameter of the rolling ring is 400 mm; the diameter of the rolling ring of each straight-diameter Y-shaped stand rolling mill group is 270 mm; the line speed at the outlet of the wire rod during the hot rolling process is 80-160 m / min;

[0062] Step S4: hot finishing rolling;

[0063] The aluminum alloy wire rod obtained in step S3 is uncoiled, and then heated to 440°C by an online heating device. After the heating is completed, the rod enters the rolling roller and first passes through 4 to 7 Y-type stand rolling mill groups for diameter reduction, and then passes through 3 straightening Y-type stand rolling mill groups for rounding to obtain a specification of 7000 series aluminum alloy wire and rod; the elements and mass fractions contained in the 7000 series aluminum alloy wire and rod are: Cu is 1.6%, Mg is 2.6%, Zn is 6.6% and Zr is 0.09%, and the balance is Al.

[0064] In this embodiment, hot rolling can achieve hot rolling from a diameter of 170 mm to a diameter of 20 mm, and the deformation is 98.62%, which is calculated as follows (ingot specifications 2 - Specifications of hot rolled wire rods 2 ) / Ingot Specifications 2 ×100%.

[0065] In step S4, the diameter of the rolled ring of each Y-type stand rolling mill group is 400 mm, and the diameter of the rolled ring of each full-diameter Y-type stand rolling mill group is 270 mm.

[0066] The hot rolling method of this embodiment is also suitable for preparing straight aluminum alloy bars (specifications are Length is about 3 to 10 meters) and round aluminum alloy wire (specifications are The length is about 2000 meters); when preparing straight aluminum alloy bars, the flying shear at the tail end of the equipment is used for shearing and segmenting; when preparing round aluminum alloy wires, one end of the finished wire is rotated around the wire-taking device to achieve winding.

[0067] Figure 1 : represents the microstructure of the 7000 series aluminum alloy wire rod prepared in Example 1; Figure 1 As shown, the aluminum alloy wire rod prepared by hot continuous rolling has a fine and uniform structure, which can effectively improve the rivet upsetting forming rate.

[0068] The 7000 series aluminum alloy round wire prepared in this example is as follows Figure 2 As shown, the weight of a single roll can reach more than 300Kg, and after heat treatment, the tensile strength can reach 600MPa and above, and the shear strength can reach 350MPa and above.

[0069] The 7000 series aluminum alloy straight bars prepared in this example are as follows: Figure 3 As shown, rods with lengths ranging from 3 to 10 meters can be prepared with high preparation efficiency. More than 100 rods can be produced within 1 hour, and the strength is equivalent to that of wire rods.

[0070] The aluminum alloy wire rod obtained by the hot rolling method of this embodiment can be subsequently cold drawn to obtain the desired cold drawn wire or cold drawn rod.

[0071] The wire prepared by the method of this embodiment can be used for the preparation of welding wires, conductive wires and fasteners. The straight bars can be used directly on large aircraft or used to prepare fastener bolts or nuts. It has huge application potential and can be used in multiple fields such as aerospace and transportation.

Claims

1. A hot rolling method for 7000 series aluminum alloy wire rod, characterized in that The preparation method is carried out according to the following steps: Step S1: Car skin; Carrying the cast aluminum alloy ingot into a car body to obtain a car body aluminum alloy ingot; Step S2: keeping warm; The aluminum alloy ingot after the car body obtained in step S1 is placed in a box-type heating furnace, heated to 400° C. to 470° C., and kept at 400° C. to 470° C. for 1 h to 3 h to obtain the aluminum alloy ingot after keeping warm; Step S3: hot rolling; The aluminum alloy ingot obtained in step S2 is sequentially hot-rolled by three sets of flat vertical roll mills, eight Y-type stand mills and four straight-diameter Y-type stand mills to obtain aluminum alloy wire rods; Step S4: hot finishing rolling; The aluminum alloy wire rod obtained in step S3 is uncoiled, and then the rod is heated to 400°C to 470°C by an online heating device. After the heating is completed, it is first reduced in diameter by 4 to 7 Y-type stand rolling mill groups, and then rounded by 3 straightening Y-type stand rolling mill groups to obtain 7000 series aluminum alloy wire rods. The 7000 series aluminum alloy wire rods contain the following elements and mass fractions: Cu is 1.6 to 2.6%, Mg is 1.6 to 2.9%, and Zn is 6.0 to 10.0%, and the balance is Al.

2. The hot rolling method of a 7000 series aluminum alloy wire rod according to claim 1, characterized in that The specification of the aluminum alloy ingot after casting in step S1 is φ140 mm to φ190 mm.

3. The hot rolling method of a 7000 series aluminum alloy wire rod according to claim 1, characterized in that In step S1, the curvature of the aluminum alloy ingot after the car body is less than 2 mm per meter of the ingot.

4. The hot rolling method of a 7000 series aluminum alloy wire rod according to claim 1, characterized in that The line speed at the wire rod outlet during the hot rolling process in step S3 is 80-160 m / min.

5. The hot rolling method of 7000 series aluminum alloy wire rod according to claim 1, characterized in that In step S3, each set of flat vertical rolling mills consists of two pairs of rolls.

6. The hot rolling method of 7000 series aluminum alloy wire rod according to claim 1, characterized in that In step S3, the diameter of the rolled ring of each Y-type stand rolling mill group is 370-500 mm, and the diameter of the rolled ring of each full-diameter Y-type stand rolling mill group is 200-300 mm.

7. The hot rolling method of 7000 series aluminum alloy wire rod according to claim 1, characterized in that The specification of the aluminum alloy wire rod described in step S3 is φ20mm~φ35mm.

8. The hot rolling method of 7000 series aluminum alloy wire rod according to claim 1, characterized in that In step S4, the diameter of the rolled ring of each Y-type stand rolling mill group is 370-500 mm, and the diameter of the rolled ring of each full-diameter Y-type stand rolling mill group is 200-300 mm.

9. The hot rolling method of 7000 series aluminum alloy wire rod according to claim 1, characterized in that The specification of the 7000 series aluminum alloy wire rod described in step S4 is φ8mm to φ13.8mm.

10. The hot rolling method of 7000 series aluminum alloy wire rod according to claim 1, characterized in that The total deformation of the 7000 series aluminum alloy wire rod described in step S4 is above 98%.

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