Magnesium alloy conical barrel and preparation method and application thereof

Abstract

The invention provides a magnesium alloy conical barrel and a preparation method and application thereof, and belongs to the technical field of magnesium alloy. The preparation method of the magnesium alloy conical barrel comprises the following steps that a magnesium alloy cast ingot is subjected to annealing treatment, and an annealed cast ingot is obtained; the cast ingot subjected to annealing treatment is subjected to multidirectional forging, and a first cast ingot is obtained; the first cast ingot is subjected to bidirectional drawing-out forging, and a second cast ingot is obtained; the second cast ingot is subjected to die forging, and a conical barrel is obtained; and the conical barrel is subjected to T6 heat treatment, and the magnesium alloy conical barrel is obtained. According to the method, the magnesium alloy ingot is subjected to annealing treatment firstly, so that residual stress can be eliminated, cracking of the ingot in the subsequent deformation process is avoided, then multidirectional forging, bidirectional drawing-out forging and die forging are adopted, and the problem that a large-size magnesium alloy ingot blank is prone to cracking due to uneven deformation in the deformation process is solved; the growth of deformed grains in the heat preservation process is effectively inhibited, and the grain size is refined.

Description

Technical Field

[0001] The invention belongs to the technical field of magnesium alloys, and in particular relates to a magnesium alloy conical cylinder and a preparation method and application thereof. Background Art

[0002] The conical tube is a key component on the missile. It has always been made of steel or aluminum alloy. However, in order to meet the requirements of weight reduction and improving fuel efficiency, designers are in urgent need of a lightweight material that can reduce the weight of the missile itself. VW93M magnesium alloy has attracted more and more attention due to its low density, excellent damping performance, high specific strength and specific stiffness. However, most magnesium alloys have a close-packed hexagonal structure with poor plastic deformation energy. They are prone to form strong deformation textures during deformation, which makes subsequent processing deformation difficult and uneven deformation of various parts, which in turn leads to processing cracking. Therefore, the large-size magnesium alloy structural parts currently used are mainly cast magnesium alloys. Therefore, how to prepare a magnesium alloy conical tube with excellent mechanical properties has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0003] The purpose of the present invention is to provide a magnesium alloy conical cylinder and a preparation method and application thereof. The magnesium alloy conical cylinder prepared by the preparation method provided by the present invention has excellent mechanical properties.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing a magnesium alloy tapered cylinder, comprising the following steps:

[0006] (1) annealing the magnesium alloy ingot to obtain an annealed ingot;

[0007] (2) performing multi-directional forging on the annealed ingot obtained in step (1) to obtain a first ingot;

[0008] (3) performing bidirectional drawing forging on the first ingot obtained in step (2) to obtain a second ingot;

[0009] (4) performing die forging on the second ingot obtained in step (3) to obtain a tapered tube;

[0010] (5) The conical tube obtained in step (4) is subjected to T6 heat treatment to obtain a magnesium alloy conical tube.

[0011] Preferably, the multidirectional forging in step (2) comprises the following steps:

[0012] 1) keeping the annealed ingot warm, then forging along the X direction and / or Y direction of the annealed ingot with the height direction of the annealed ingot as the Z direction, and then rolling forging with the Z direction as the axis to obtain a billet;

[0013] 2) Repeat the operation of step 1) to obtain a first ingot.

[0014] Preferably, in step 1), the pressing speed for forging along the X direction and / or Y direction of the annealed ingot is 6-10 mm / s, and the single-pass pressing reduction for forging along the X direction and / or Y direction of the annealed ingot is 20-40%.

[0015] Preferably, the number of rolling forging passes in step 1) is 3 to 6, and the deformation amount of a single rolling forging pass is 10 to 20%.

[0016] Preferably, the bidirectional drawing forging in step (3) comprises the following steps:

[0017] ① The first ingot is kept warm, and then forged along the diameter direction of the first ingot to obtain an ingot blank;

[0018] ② Repeat step ① to obtain a second ingot.

[0019] Preferably, in step ①, the forging reduction speed is 3 to 6 mm / s, the forging reduction amount in a single pass is 5 to 20%, and the number of forging passes is 2 to 8.

[0020] Preferably, the die forging in step (4) includes primary die forging and secondary die forging performed sequentially.

[0021] Preferably, the forging speed of the primary die forging is 2-5 mm / s, and the deformation ratio of the primary die forging is 0.20-0.40; the forging speed of the secondary die forging is 2-5 mm / s, and the deformation ratio of the secondary die forging is 0.75-0.83.

[0022] The present invention also provides a magnesium alloy conical cylinder prepared by the preparation method described in the above technical solution.

[0023] The present invention also provides the application of the magnesium alloy conical tube described in the above technical solution in a missile.

[0024] The present invention provides a method for preparing a magnesium alloy tapered tube, comprising the following steps: annealing a magnesium alloy ingot to obtain an annealed ingot; multi-directional forging the annealed ingot to obtain a first ingot; bidirectional drawing forging the first ingot to obtain a second ingot; die forging the second ingot to obtain a tapered tube; and T6 heat treatment the tapered tube to obtain a magnesium alloy tapered tube. The present invention first anneals the magnesium alloy ingot to eliminate residual stress and avoid cracking of the ingot in the subsequent deformation process. Then, multi-directional forging, bidirectional drawing forging and die forging are used to solve the problem that large-sized magnesium alloy ingots are prone to cracking due to uneven deformation during the deformation process, effectively inhibit the growth of deformed grains during the insulation process, and significantly refine the grain size of the finished product. Experimental results show that the room temperature mechanical properties of the magnesium alloy conical cylinder prepared by the preparation method provided by the present invention are: yield strength 326-331MPa, tensile strength 418-425MPa, elongation 10-11%; 250°C mechanical properties: yield strength 261-267MPa, tensile strength 351-363MPa, elongation 14-15%. DETAILED DESCRIPTION

[0025] The present invention provides a method for preparing a magnesium alloy tapered cylinder, comprising the following steps:

[0026] (1) annealing the magnesium alloy ingot to obtain an annealed ingot;

[0027] (2) performing multi-directional forging on the annealed ingot obtained in step (1) to obtain a first ingot;

[0028] (3) performing bidirectional drawing forging on the first ingot obtained in step (2) to obtain a second ingot;

[0029] (4) performing die forging on the second ingot obtained in step (3) to obtain a tapered tube;

[0030] (5) The conical tube obtained in step (4) is subjected to T6 heat treatment to obtain a magnesium alloy conical tube.

[0031] The present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0032] The present invention performs annealing treatment on the magnesium alloy ingot to obtain the annealed ingot.

[0033] In the present invention, the magnesium alloy ingot is preferably a VW93M magnesium alloy ingot; the chemical composition of the VW93M magnesium alloy ingot is preferably, by mass percentage, Gd 8.0-9.6%, Y 1.8-3.2%, Zr0.3-0.7%, Er 0.02-0.3%, Ag 0.02-0.50% and the balance Mg, further preferably Gd 8.3-9.3%, Y 2.1-2.7%, Zr0.35-0.6%, Er 0.05-0.25%, Ag 0.1-0.40% and the balance Mg, more preferably Gd 8.5-9.0%, Y2.3-2.4%, Zr 0.45-0.55%, Er 0.15-0.20%, Ag 0.2-0.35% and the balance Mg. The present invention can further improve the strength and heat resistance of the magnesium alloy by limiting the chemical component content of the VW93M magnesium alloy ingot within the above range.

[0034] In the present invention, the mass ratio of Gd to Y is preferably: 3≤Gd / Y≤5; the mass ratio of Ag to Er is preferably: 1≤Ag / Er≤3. The present invention can obtain excellent rare earth precipitate phase morphology distribution by controlling the content ratio of Gd to Y and the mass ratio of Ag to Er.

[0035] In the present invention, the magnesium alloy ingot is preferably prepared by electromagnetic semi-continuous casting. The present invention has no special limitation on the specific operation of the electromagnetic semi-continuous casting, and the ingot can be prepared by a preparation method well known to those skilled in the art. The present invention adopts the electromagnetic semi-continuous casting method to prepare the magnesium alloy ingot, which can reduce defects such as inclusions, pores, looseness and center cracks, thereby reducing its cracking tendency in the subsequent deformation process and improving the formability of the magnesium alloy in the subsequent deformation process.

[0036] In the present invention, the diameter of the magnesium alloy ingot is preferably 340-630 mm; the length of the magnesium alloy ingot is preferably ≥2000 mm.

[0037] In the present invention, the annealing treatment preferably includes stress relief annealing and homogenization treatment performed sequentially.

[0038] In the present invention, the holding temperature of the stress relief annealing is preferably 200-300°C; the holding time of the stress relief annealing is preferably 10-15h. As an embodiment, the holding temperature of the stress relief annealing can be 250-280°C; the holding time of the stress relief annealing can be 12-14h. The stress relief annealing of the magnesium alloy ingot by the present invention can eliminate residual stress, avoid cracking of the ingot in the subsequent deformation process, and improve surface accuracy. It can not only avoid excessive holding time, which leads to excessive grain growth and excessive precipitation, aggregation and coarsening of the second phase, resulting in reduced strength, but also avoid too low holding time, which makes it impossible to fully eliminate the residual stress inside the alloy and reduce the strength of the alloy.

[0039] In the present invention, the holding temperature of the homogenization treatment is preferably 480-520°C; the holding time of the homogenization treatment is preferably 18-24h. As an embodiment, the holding temperature of the homogenization treatment can be 490-500°C; the holding time of the homogenization treatment can be 20-22h. In the present invention, limiting the process parameters of the homogenization treatment within the above range can further improve the plasticity of the alloy.

[0040] The present invention has no particular limitation on the heating rates of the stress relief annealing and homogenization treatment, and any rate known to those skilled in the art may be used.

[0041] After the annealing treatment is completed, the present invention preferably sequentially cools, machine-peels and cuts the product obtained by the annealing treatment to obtain an annealed ingot.

[0042] In the present invention, the cooling is preferably air cooling. The present invention has no special limitation on the operation of the air cooling, and air cooling to room temperature can be performed by an operation well known to those skilled in the art.

[0043] The present invention has no special limitation on the machining peeling and blanking operations, and operations well known to those skilled in the art may be adopted.

[0044] In the present invention, the shape of the annealed ingot is preferably cylindrical.

[0045] After obtaining the annealed ingot, the present invention performs multi-directional forging on the annealed ingot to obtain a first ingot.

[0046] In the present invention, the multidirectional forging preferably includes the following steps:

[0047] 1) keeping the annealed ingot warm, then forging along the X direction and / or Y direction of the annealed ingot with the height direction of the annealed ingot as the Z direction, and then rolling forging with the Z direction as the axis to obtain a billet;

[0048] 2) Repeat the operation of step 1) to obtain a first ingot. The present invention maintains the magnesium alloy within a suitable processing temperature range by repeating the heat preservation and forging process, avoids the billet temperature from being too low, and ensures the continuity and high efficiency of production.

[0049] The present invention preferably keeps the annealed ingot warm, then forges the annealed ingot along the X direction and / or Y direction with the height direction of the annealed ingot as the Z direction, and then rolls the ingot with the Z direction as the axis to obtain a billet.

[0050] In the present invention, the insulation temperature is preferably 450-520°C; the insulation time is preferably 10-20 hours. The present invention limits the insulation process parameters within the above range to avoid the danger of overburning caused by too high insulation temperature and ensure the deformation ability of the alloy.

[0051] In the present invention, the forging equipment is preferably preheated before forging, and the preheating temperature is preferably 200-350° C. The present invention has no particular limitation on the preheating time, as long as the equipment is preheated to within the above range.

[0052] In the present invention, the forging equipment is preferably upper and lower flat anvils. The present invention has no special limitation on the model of the upper and lower flat anvils, and the instruments and equipment well known to those skilled in the art can be used. The present invention preheats the upper and lower flat anvils before forging, which can prevent the magnesium alloy billet from cooling down at an extremely fast speed and causing cracking.

[0053] In the present invention, the pressing speed of forging along the X direction and / or Y direction of the annealed ingot is preferably 6-10 mm / s; the single-pass pressing amount of forging along the X direction and / or Y direction of the annealed ingot is preferably 20-40%; the number of passes of forging along the X direction and / or Y direction of the annealed ingot is preferably 2-5. The present invention can press a cylindrical ingot into a hexahedron by forging along the X direction and / or Y direction of the annealed ingot. The present invention limits the forging process parameters within the above range to further improve the mechanical properties and heat resistance of the magnesium alloy.

[0054] As an embodiment, the pressing speed of forging along the X direction and / or Y direction of the annealed ingot can be 7-8 mm / s; the single-pass pressing amount of forging along the X direction and / or Y direction of the annealed ingot can be 25-35%, or 30%; the number of passes of forging along the X direction and / or Y direction of the annealed ingot can be 2-4.

[0055] In the present invention, the number of passes of the rolling forging is preferably 3 to 6; the deformation of a single pass of the rolling forging is preferably 10 to 20%. As an embodiment, the number of passes of the rolling forging can be 4 to 5; the deformation of a single pass of the rolling forging can be 15 to 20%. In the present invention, the rolling forging can compress the edges and corners of the ingot and press the 6-hedron into a 12 to 18-hedron. The present invention limits the process parameters of the rolling forging within the above range to further improve the mechanical properties and heat resistance of the magnesium alloy.

[0056] After obtaining the blank, the present invention preferably repeats the aforementioned heat preservation and forging operations to obtain a first ingot.

[0057] In the present invention, the number of repetitions is preferably 1 to 2 times.

[0058] In the present invention, the diameter of the first ingot is preferably 400-500 mm; the height of the first ingot is preferably 600-800 mm.

[0059] After obtaining the first ingot, the present invention performs bidirectional drawing forging on the first ingot to obtain the second ingot.

[0060] In the present invention, the bidirectional drawing forging preferably includes the following steps:

[0061] ① The first ingot is kept warm, and then forged along the diameter direction of the first ingot to obtain an ingot blank;

[0062] ② Repeat step ① to obtain a second ingot.

[0063] The present invention preferably keeps the first ingot warm, and then forges it along the diameter direction of the first ingot to obtain an ingot blank.

[0064] In the present invention, the insulation temperature is preferably 430-500°C; the insulation time is preferably 8-18h. The present invention limits the insulation process parameters within the above range to avoid the danger of overburning caused by too high insulation temperature and ensure the deformation ability of the alloy.

[0065] In the present invention, the forging equipment is preferably preheated before forging; the preheating temperature is preferably 200-300° C. The present invention has no particular limitation on the preheating time, as long as the equipment is preheated to within the above range.

[0066] In the present invention, the forging equipment is preferably upper and lower flat anvils. The present invention has no special limitation on the model of the upper and lower flat anvils, and the instruments and equipment well known to those skilled in the art can be used. The present invention preheats the upper and lower flat anvils before forging, which can prevent the magnesium alloy billet from cooling down at an extremely fast speed and causing cracking.

[0067] In the present invention, the forging reduction speed is preferably 3-6 mm / s; the forging reduction in a single pass is preferably 5-20%; and the number of forging passes is preferably 2-8. As an embodiment, the forging reduction speed can be 4-5 mm / s; the forging reduction in a single pass can be 10-15%; and the number of forging passes can be 5-6. The present invention limits the forging process parameters within the above range to further improve the mechanical properties and heat resistance of the magnesium alloy, and can avoid the reduction speed being too fast, resulting in uneven deformation of the material during forging, and the reduction speed being too slow, resulting in the material staying at high temperature for too long, thereby causing grain growth; it can also avoid the reduction in the pass being too low, resulting in the difficulty in eliminating the internal structural heterogeneity of the material, and the reduction in the pass being too high, resulting in excessive stress inside the material, and cracks inside the material.

[0068] After obtaining the ingot, the present invention preferably repeats the aforementioned heat preservation and forging operations to obtain a second ingot.

[0069] In the present invention, the number of repetitions is preferably 2 to 4. As an embodiment, the number of repetitions may be 3.

[0070] In the present invention, the diameter of the second ingot is preferably 250-350 mm; the height of the second ingot is preferably 1000-1400 mm.

[0071] After obtaining the second ingot, the present invention performs die forging on the second ingot to obtain a tapered tube.

[0072] In the present invention, the second ingot is preferably processed and kept warm in sequence before the die forging.

[0073] In the present invention, the processing is preferably to process one end of the second ingot into a conical surface and the center of the other end into a groove. The present invention processes both ends of the second ingot to ensure centering and avoid eccentricity during die forging.

[0074] The present invention has no special limitation on the sizes of the conical surface and the groove, and they can be adjusted according to actual needs.

[0075] As an implementation manner, the height of the cone surface may be ≥60 mm, and the angle of the cone surface may be 8°; the depth of the groove may be ≥10 mm, and the radius of the groove may be 40-80 mm.

[0076] In the present invention, the insulation temperature is preferably 400-480°C; the insulation time is preferably 6-10 hours. The present invention limits the insulation process parameters within the above range to avoid the danger of overburning caused by too high insulation temperature and ensure the deformation ability of the alloy.

[0077] In the present invention, the die forging die is preferably heat-insulated before die forging; the heat-insulating temperature is preferably 350-450°C; the heat-insulating time is preferably 5-15h. In the present invention, heat-insulating the die forging die can prevent the magnesium alloy from cracking during die forging.

[0078] In the present invention, the die forging preferably includes primary die forging and secondary die forging performed sequentially.

[0079] In the present invention, the conical surface of the second ingot is preferably facing downward during the primary die forging; and the upper flat die is preferably used for the primary die forging.

[0080] In the present invention, the forging speed of the single die forging is preferably 2-5 mm / s; the deformation ratio of the single die forging is preferably 0.20-0.40; and the reduction amount of the single die forging is preferably 200-400 mm. As an embodiment, the forging speed of the single die forging can be 3-4 mm / s; the deformation ratio of the single die forging can be 0.25-0.35, or 0.30; and the reduction amount of the single die forging can be 250-300 mm. The present invention limits the forging speed of the single die forging within the above range to ensure uniform deformation of the billet, without cracking and uneven structure, and optimizes the performance of the alloy after deformation.

[0081] In the present invention, the height of the product obtained by the one-time die forging is preferably 800 to 1200 mm.

[0082] In the present invention, the product obtained by the primary die forging is preferably kept warm before the secondary die forging; the temperature of the keeping warm is preferably 400-480°C; and the time of the keeping warm is preferably 4-8 hours. As an embodiment, the temperature of the keeping warm can be 420-460°C, or 450°C; and the time of the keeping warm can be 5-6 hours. The present invention limits the process parameters of the keeping warm to the above range, which not only avoids the danger of overburning caused by too high a keeping warm temperature, but also ensures the deformation ability of the alloy.

[0083] In the present invention, the die forging die is preferably heat-insulated before the secondary die forging; the heat-insulating temperature is preferably 350-450°C; the heat-insulating time is preferably 5-15 hours. The present invention heat-insulates the die forging die to prevent the magnesium alloy from cracking during die forging.

[0084] In the present invention, during the secondary die forging, the conical surface of the product obtained by the primary die forging is preferably facing downward; during the secondary die forging, an upper conical die is preferably used for die forging.

[0085] In the present invention, the forging speed of the secondary die forging is preferably 2-5 mm / s; the deformation ratio of the secondary die forging is preferably 0.75-0.83; and the reduction amount of the secondary die forging is preferably 600-1000 mm. As an embodiment, the forging speed of the secondary die forging can be 3-4 mm / s; the deformation ratio of the secondary die forging can be 0.78-0.80; and the reduction amount of the secondary die forging can be 600-800 mm. The present invention limits the forging speed of the secondary die forging within the above range to ensure uniform deformation of the billet, without cracking and uneven structure, and optimizes the performance of the alloy after deformation.

[0086] In the present invention, the height of the conical cylinder is preferably 1000-1200 mm; the top diameter of the conical cylinder is preferably 200-250 mm; the bottom outer diameter of the conical cylinder is preferably 500-600 mm; the cone barrel depth of the conical cylinder is preferably 800-1000 mm; and the wall thickness of the conical cylinder is preferably 80-100 mm.

[0087] After obtaining the conical cylinder, the present invention performs T6 heat treatment on the conical cylinder to obtain a magnesium alloy conical cylinder.

[0088] In the present invention, the T6 heat treatment preferably includes solution treatment and aging treatment performed in sequence. The present invention adopts T6 heat treatment to make the comprehensive mechanical properties of the tapered tube more excellent.

[0089] In the present invention, the holding temperature of the solution treatment is preferably 380-450°C; the holding time of the solution treatment is preferably 30-120 min. As an embodiment, the holding temperature of the solution treatment can be 400-420°C, and the holding time of the solution treatment can be 60-100 min. The present invention limits the process parameters of the solution treatment within the above range, which can effectively eliminate internal stress concentration and non-uniformity, is conducive to grain refinement and uniform distribution of the second phase, thereby improving the mechanical properties of the alloy.

[0090] After the solution treatment is completed, the present invention preferably performs water quenching on the product obtained by the solution treatment; the temperature of the water quenching is preferably 60-70° C. The present invention performs water quenching after the solution treatment to prevent surface cracking.

[0091] In the present invention, the holding temperature of the aging treatment is preferably 200-250°C; the holding time of the aging treatment is preferably 12-40h. As an embodiment, the holding temperature of the aging treatment can be 220-240°C, and the holding time of the aging treatment can be 16-20h. The present invention limits the process parameters of the aging treatment within the above range, which can effectively eliminate internal stress concentration and non-uniformity, is conducive to grain refinement and uniform distribution of the second phase, thereby improving the mechanical properties of the alloy.

[0092] After the T6 heat treatment is completed, the present invention preferably cools the product obtained by the T6 heat treatment to obtain a magnesium alloy conical cylinder.

[0093] In the present invention, the cooling is preferably air cooling. The present invention has no special limitation on the operation of the air cooling, and air cooling to room temperature can be performed by an operation well known to those skilled in the art.

[0094] Aiming at the actual demand of large-size magnesium alloy conical parts for missiles in the aerospace field, the present invention designs the forming process of VW93M magnesium alloy conical barrel die forgings for the first time based on VW93M alloy by adopting a process combining multi-directional forging, bidirectional drawing and die forging, and prepares magnesium alloy conical parts with a top diameter of φ200-250mm, a bottom outer diameter of φ500-600mm, a height of 1000-1200mm, a wall thickness of 80-100mm, and a cone barrel depth of 800-1000mm. This process is of great significance to promoting the wide application of magnesium alloys in the aerospace field.

[0095] The present invention adopts a flat anvil to perform a primary die forging and then a cone head to perform a secondary die forging during die forging, and after bidirectional drawing, a cone surface is processed at one end of the ingot, and a central groove at the other end is used for positioning the lower cone die and the cone head. The die forging effectively solves the problem of instability that is easy to occur during deformation of a large-size variable-section magnesium alloy ingot with a height-to-diameter ratio greater than 3, avoids the problem of eccentricity that is easy to occur during the deformation of the cone tube, and further ensures uniform deformation in the wall thickness direction of the cone tube.

[0096] The room temperature mechanical properties of the magnesium alloy conical cylinder prepared by the preparation method provided by the present invention are: tensile strength ≥415MPa, yield strength ≥325MPa, elongation ≥10%; the mechanical properties at 250°C are: tensile strength ≥350MPa, yield strength ≥260MPa, elongation ≥14.0%.

[0097] The magnesium alloy conical cylinder prepared by the present invention has the characteristics of large size, no cracks, ultra-high room temperature strength and excellent heat resistance, and can provide qualified magnesium alloy conical cylinder parts for the fields of aerospace and aviation.

[0098] The present invention also provides a magnesium alloy conical cylinder prepared by the preparation method described in the above technical solution.

[0099] The present invention also provides the application of the magnesium alloy conical tube described in the above technical solution in a missile.

[0100] The present invention has no special limitation on the operation of applying the magnesium alloy conical tube in the missile, and the application operation well known to those skilled in the art can be adopted.

[0101] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0102] Example 1

[0103] The preparation method of the magnesium alloy conical cylinder comprises the following steps:

[0104] (1) A magnesium alloy ingot with a diameter of 410 mm and a length of 3000 mm is prepared by an electromagnetic semi-continuous casting method, and then stress relief annealing is performed at 250° C. for 12 h, followed by homogenization treatment at 500° C. for 20 h, followed by air cooling to room temperature, and then machining, peeling and blanking to obtain an annealed ingot; wherein the mass percentage composition of the magnesium alloy ingot is: Mg-9.07Gd-2.18Y-0.33Zr-0.21Ag-0.23Er;

[0105] (2) The annealed ingot was kept at 510°C for 11 hours, the upper and lower flat anvils were preheated to 350°C, and then forged in two passes along the X direction of the annealed ingot on a 3000-ton vertical hydraulic press with the height direction of the annealed ingot as the Z direction at a speed of 6 mm / s and a pass reduction of 40%. Then, the annealed ingot was forged in two passes along the Y direction at a speed of 6 mm / s and a pass reduction of 40% to press the cylinder into a hexahedron, and then the hexahedron was rolled forged six times with the Z direction as the axis to press the hexahedron into a dodecahedron to obtain a blank; wherein the deformation of a single pass of the rolling forging was 20%;

[0106] (3) Repeat step (2) twice to obtain a cylindrical first ingot with a diameter of 500 mm and a height of 620 mm;

[0107] (4) The first ingot obtained in step (3) is kept at 500° C. for 8 h, the upper and lower flat anvils are preheated to 300° C., and forged along the diameter direction of the first ingot on a vertical hydraulic press to obtain an ingot blank; wherein the forging pressing speed is 4 mm / s, the single pass pressing amount is 5%, and the number of passes is 6;

[0108] (5) Repeat step (4) 4 times to obtain a second cylindrical ingot with a diameter of 300 mm and a height of 1300 mm;

[0109] (6) One end of the second ingot obtained in step (5) is processed into a 60 mm high conical surface with an angle of 8°, and the center of the other end is processed into a groove with a depth of 10 mm and R80 mm, and then the ingot is kept at 480° C. for 10 h, and the mold is kept at 450° C. for 15 h. Subsequently, the conical surface of the second ingot is facing downward in a 12,500-ton hydraulic press, and a die forging is performed with an upper flat die. The forging speed is 3 mm / s, the pressing amount is 300 mm, and the deformation ratio is 0.4, so as to obtain a high 1000mm conical magnesium alloy ingot; then keep it at 480℃ for 5h, keep the mold at 450℃ for 5h, put the magnesium alloy ingot with the cone surface facing down in a 12500-ton hydraulic press, and use the upper cone die for secondary die forging, the forging speed is 3mm / s, the pressing amount is 600mm, the deformation ratio is 0.83, and a conical barrel with a top diameter of 250mm, a bottom outer diameter of 530mm, a height of 1000mm, a wall thickness of 86mm, and a cone barrel depth of 800mm is obtained;

[0110] (7) The conical tube obtained in step (6) is subjected to solution treatment at a temperature of 420° C. for 120 min, then quenched with 70° C. hot water, and then subjected to aging treatment at a temperature of 220° C. for 16 h, and air-cooled to room temperature to obtain a magnesium alloy conical tube.

[0111] The magnesium alloy conical cylinder prepared in Example 1 was subjected to a performance test. The test standard was GBT 16865-2013 Specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products. The test results were: room temperature mechanical properties: tensile strength 419 MPa, yield strength 328 MPa, elongation 10%; 250°C mechanical properties: tensile strength 351 MPa, yield strength 262 MPa, elongation 15.0%.

[0112] Example 2

[0113] The preparation method of the magnesium alloy conical cylinder comprises the following steps:

[0114] (1) A magnesium alloy ingot with a diameter of 420 mm and a length of 3000 mm is prepared by an electromagnetic semi-continuous casting method, and then stress relief annealing is performed at 250° C. for 12 h, followed by homogenization treatment at 500° C. for 20 h, followed by air cooling to room temperature, and then machining, peeling and blanking to obtain an annealed ingot; wherein the mass percentage composition of the magnesium alloy ingot is: Mg-8.95Gd-2.76Y-0.40Zr-0.21Ag-0.14Er;

[0115] (2) The annealed ingot was kept at 510°C for 12 hours, the upper and lower flat anvils were preheated to 350°C, and then forged in two passes along the X direction of the annealed ingot on a 3000-ton vertical hydraulic press with the height direction of the annealed ingot as the Z direction at a speed of 8 mm / s and a pass reduction of 30%, and then forged in two passes along the Y direction of the annealed ingot at a speed of 6 mm / s and a pass reduction of 40%, to press the cylinder into a hexahedron, and then roll forging was performed four times with the Z direction as the axis to press the hexahedron into a dodecahedron to obtain a billet; wherein the deformation of a single pass of the rolling forging is 15%;

[0116] (3) Repeat step (2) twice to obtain a cylindrical first ingot with a diameter of 500 mm and a height of 610 mm;

[0117] (4) The first ingot obtained in step (3) is kept at 500° C. for 8 h, the upper and lower flat anvils are preheated to 250° C., and forged along the diameter direction of the first ingot on a vertical hydraulic press to obtain an ingot blank; wherein the forging pressing speed is 5 mm / s, the single pass pressing amount is 5%, and the number of passes is 6;

[0118] (5) Repeat step (4) 4 times to obtain a second cylindrical ingot with a diameter of 290 mm and a height of 1320 mm;

[0119] (6) One end of the second ingot obtained in step (5) is processed into a 60 mm high conical surface with an angle of 8°, and the center of the other end is processed into a groove with a depth of 10 mm and R80 mm, and then the ingot is kept at 480° C. for 11 h, and the mold is kept at 450° C. for 15 h. Subsequently, the second ingot is placed with the conical surface facing downward in a 12,500 ton hydraulic press and forged once with an upper flat die. The forging speed is 4 mm / s, the pressing amount is 300 mm, and the deformation ratio is 0.2 to obtain a high 1000mm conical magnesium alloy ingot; then keep it at 480℃ for 4h, keep the mold at 450℃ for 5h, put the magnesium alloy ingot with the cone surface facing down in a 12500-ton hydraulic press, and use the upper cone die for secondary die forging, the forging speed is 4mm / s, the pressing amount is 600mm, the deformation ratio is 0.75, and a conical barrel with a top diameter of 250mm, a bottom outer diameter of 540mm, a height of 1000mm, a wall thickness of 90mm, and a cone barrel depth of 800mm is obtained;

[0120] (7) The conical tube obtained in step (6) is subjected to solution treatment at a temperature of 420° C. for 120 min, then quenched with 70° C. hot water, and then subjected to aging treatment at a temperature of 220° C. for 16 h, and air-cooled to room temperature to obtain a magnesium alloy conical tube.

[0121] The magnesium alloy tapered cylinder prepared in Example 2 was subjected to a performance test. The test standard was GBT 16865-2013 Specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products. The test results were as follows: room temperature mechanical properties: tensile strength 418 MPa, yield strength 326 MPa, elongation 10%; 250°C mechanical properties: tensile strength 363 MPa, yield strength 267 MPa, elongation 14.0%.

[0122] Example 3

[0123] The preparation method of the magnesium alloy conical cylinder comprises the following steps:

[0124] (1) A magnesium alloy ingot with a diameter of 410 mm and a length of 3000 mm is prepared by an electromagnetic semi-continuous casting method, and then stress relief annealing is performed at 250° C. for 12 h, followed by homogenization treatment at 500° C. for 20 h, followed by air cooling to room temperature, and then machining, peeling and blanking to obtain an annealed ingot; wherein the mass percentage composition of the magnesium alloy ingot is: Mg-8.85Gd-2.66Y-0.40Zr-0.20Ag-0.15Er;

[0125] (2) The annealed ingot was kept at 510°C for 12 hours, the upper and lower flat anvils were preheated to 350°C, and then forged in two passes along the X direction of the annealed ingot on a 3000-ton vertical hydraulic press with the height direction of the annealed ingot as the Z direction at a speed of 10 mm / s and a pass reduction of 30%, and then forged in two passes along the Y direction of the annealed ingot at a speed of 10 mm / s and a pass reduction of 40%, to press the cylinder into a hexahedron, and then roll forging was performed four times with the Z direction as the axis to press the hexahedron into a dodecahedron to obtain a billet; wherein the deformation of a single pass of the rolling forging is 10%;

[0126] (3) Repeat step (2) twice to obtain a cylindrical first ingot with a diameter of 500 mm and a height of 610 mm;

[0127] (4) The first ingot obtained in step (3) is kept at 500° C. for 8 h, the upper and lower flat anvils are preheated to 250° C., and forged along the diameter direction of the first ingot on a vertical hydraulic press to obtain an ingot blank; wherein the forging pressing speed is 5 mm / s, the single pass pressing amount is 20%, and the number of passes is 8;

[0128] (5) Repeat step (4) 4 times to obtain a second cylindrical ingot with a diameter of 290 mm and a height of 1320 mm;

[0129] (6) One end of the second ingot obtained in step (5) is processed into a 60 mm high conical surface with an angle of 8°, and the center of the other end is processed into a groove with a depth of 10 mm and R80 mm, and then the ingot is kept at 480° C. for 11 h, and the mold is kept at 450° C. for 15 h. Subsequently, the second ingot is placed with the conical surface facing downward in a 12,500 ton hydraulic press and forged once with an upper flat die. The forging speed is 4 mm / s, the pressing amount is 300 mm, and the deformation ratio is 0.2 to obtain a high 1000mm conical magnesium alloy ingot; then keep it at 480℃ for 4h, keep the mold at 450℃ for 5h, put the magnesium alloy ingot with the cone surface facing down in a 12500-ton hydraulic press, and use the upper cone die for secondary die forging, the forging speed is 4mm / s, the pressing amount is 600mm, the deformation ratio is 0.75, and a conical barrel with a top diameter of 250mm, a bottom outer diameter of 540mm, a height of 1000mm, a wall thickness of 90mm, and a cone barrel depth of 800mm is obtained;

[0130] (7) The conical tube obtained in step (6) is subjected to solution treatment at a temperature of 420° C. for 120 min, then quenched with 70° C. hot water, and then subjected to aging treatment at a temperature of 220° C. for 16 h, and air-cooled to room temperature to obtain a magnesium alloy conical tube.

[0131] The magnesium alloy conical cylinder prepared in Example 3 was subjected to performance testing. The test standard was GBT 16865-2013 Specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products. The test results were: room temperature mechanical properties: tensile strength 425 MPa, yield strength 331 MPa, elongation 11%; 250°C mechanical properties: tensile strength 360 MPa, yield strength 261 MPa, elongation 14.0%.

[0132] It can be seen from the above embodiments that the magnesium alloy conical cylinder prepared by the preparation method provided by the present invention has excellent mechanical properties.

[0133] 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 modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a magnesium alloy tapered cylinder, comprising the following steps: (1) annealing the magnesium alloy ingot to obtain an annealed ingot; (2) performing multi-directional forging on the annealed ingot obtained in step (1) to obtain a first ingot; (3) performing bidirectional drawing forging on the first ingot obtained in step (2) to obtain a second ingot; (4) performing die forging on the second ingot obtained in step (3) to obtain a tapered tube; (5) The conical tube obtained in step (4) is subjected to T6 heat treatment to obtain a magnesium alloy conical tube.

2. The preparation method according to claim 1, characterized in that: The multidirectional forging in step (2) comprises the following steps: 1) keeping the annealed ingot warm, then forging along the X direction and / or Y direction of the annealed ingot with the height direction of the annealed ingot as the Z direction, and then rolling forging with the Z direction as the axis to obtain a billet; 2) Repeat the operation of step 1) to obtain a first ingot.

3. The preparation method according to claim 2, characterized in that: In the step 1), the pressing speed for forging along the X direction and / or Y direction of the annealed ingot is 6-10 mm / s, and the single pass pressing amount forging along the X direction and / or Y direction of the annealed ingot is 20-40%.

4. The preparation method according to claim 2, characterized in that: The number of rolling forging passes in step 1) is 3 to 6, and the deformation amount of a single rolling forging pass is 10 to 20%.

5. The preparation method according to claim 1, characterized in that: The bidirectional drawing forging in step (3) comprises the following steps: ① The first ingot is kept warm, and then forged along the diameter direction of the first ingot to obtain an ingot blank; ② Repeat step ① to obtain a second ingot.

6. The preparation method according to claim 5, characterized in that: In the step ①, the forging reduction speed is 3-6 mm / s, the forging reduction amount in a single pass is 5-20%, and the number of forging passes is 2-8.

7. The preparation method according to claim 1, characterized in that: The die forging in step (4) includes primary die forging and secondary die forging performed sequentially.

8. The preparation method according to claim 7, characterized in that: The forging speed of the primary die forging is 2-5 mm / s, and the deformation ratio of the primary die forging is 0.20-0.40; the forging speed of the secondary die forging is 2-5 mm / s, and the deformation ratio of the secondary die forging is 0.75-0.

83.

9. The magnesium alloy tapered cylinder prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the magnesium alloy conical tube according to claim 9 in missiles.