Preparation method of TB9 titanium alloy large-disc round wire for self-plugging rivet

Abstract

The invention relates to the technical field of machining of titanium alloy wires for self-plugging rivets, in particular to a preparation method of a TB9 titanium alloy large-disc round wire for a self-plugging rivet. The method comprises the following steps: firstly, obtaining a TB9 titanium alloy cast ingot with the diameter of 500-700mm, then cogging and forging the TB9 titanium alloy cast ingot at the temperature of 1100-1200 DEG C to form a bar billet with the diameter of 290-310mm, then roughly forging the TB9 titanium alloy bar billet at the temperature of 1000-1100 DEG C to form a bar billet with the diameter of 130-150mm, then precisely forging the TB9 titanium alloy bar billet at the temperature of 850-950 DEG C to form a bar billet with the diameter of 95-105mm, then continuously rolling the TB9 titanium alloy bar billet at the temperature of 780-900 DEG C, quenching after rolling to obtain a large-disc round wire billet with the diameter of 7.5-15mm, drawing at room temperature, and finally obtaining the large-disc round wire billet. And then carrying out high-temperature solid solution treatment, drawing at room temperature, peeling, polishing and coating treatment. At the moment, the cross section structure of the alloy is a fine and uniform equiaxed structure, the longitudinal section structure of the alloy is an elongated fibrous structure, and after aging treatment, the mechanical property requirements specified by AMS4957F on the TB9 titanium alloy wire are met.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy wire processing for blind rivets, and in particular to a method for preparing a TB9 titanium alloy large coil wire for blind rivets. Background Art

[0002] Titanium alloy bulge-type blind rivets are mainly used for single-sided connection of composite materials. They have excellent performance characteristics, mainly reflected in light weight, high specific strength, corrosion resistance, preload, locking, fatigue resistance, lightning protection, sealing and other aspects; they also solve the problems of potential compatibility, installation damage, low pull-off strength and other problems unique to composite materials. Titanium alloy blind rivets are mainly used for structural connection of materials in aircraft fairings, elevators, ailerons, wingtips, rear end of fuselage, leading and trailing edges, cargo hold floors, landing gear doors, passenger / aircrew doors, cabin doors and other parts, and the single machine consumption is large.

[0003] TB9 alloy is a high-strength metastable β titanium alloy. Through appropriate heat treatment, its room temperature tensile strength can exceed 1500MPa, and it has good corrosion resistance, hardenability and room temperature deformation ability. TB9 alloy also has excellent shear and fatigue properties, making TB9 alloy an ideal material for producing high-strength titanium alloy blind rivet core rods. At present, most of the TB9 titanium alloy wires used for blind rivet core rods in China are processed in small batches, mainly rolled on horizontal rolling mills, and the finished products are mainly small single weight coils (less than 30kg) and straight strips. The consistency of product quality is difficult to guarantee, resulting in large fluctuations in the mechanical properties of the prepared blind rivet core rods, and it is difficult to guarantee the stability of product quality.

[0004] Therefore, it is of great engineering significance to study the preparation process of large single weight coiled TB9 titanium alloy wire (specification Φ2~15mm, single coil weight ≥100kg) to prepare high-quality and high-uniformity large single weight coiled TB9 titanium alloy wire. Summary of the invention

[0005] Based on this, it is necessary to address the above technical problems. The purpose of the present invention is to provide a method for preparing large-scale round wire of TB9 titanium alloy for blind rivets. The TB9 titanium alloy wire prepared by this method has fine and uniform microstructure, good consistency, high strength, good plasticity, and good surface quality and dimensional tolerance.

[0006] The technical solution of the present invention is:

[0007] A method for preparing a large-scale round wire of TB9 titanium alloy for blind rivets, the specific steps are as follows:

[0008] Step 1, prepare ingot: take TB9 titanium alloy ingot with a diameter of 500-700 mm, and the composition of TB9 titanium alloy ingot is as follows by weight percentage: Al 3.00-4.00%, V 7.50-8.50%, Cr 5.50-6.50%, Mo 3.50-4.50%, Zr 3.50-4.50%, Fe≤0.30%, O≤0.14%, C≤0.05%, N≤0.03%, H≤0.03%, Y≤0.005%, the total of impurity elements ≤0.40%, and the balance is Ti;

[0009] Step 2, billet forging: heat the heating furnace to 850-950℃ to load the ingot, raise the temperature to 1100-1200℃, keep the temperature for 2-3h, and stretch the billet on the forging machine. After stretching, the diameter of the billet is 290-310mm, the total deformation is 70-80%, and the surface defects are repaired;

[0010] Step 3, rough forging: heat the heating furnace to 800-900℃ to load the billet, raise the temperature to 1000-1100℃, keep it at temperature for 2-3h, take it out of the furnace and stretch it on the forging machine. After stretching, the diameter of the billet is 130-150mm, and the total deformation is 70-90%. The billet is rough forged and the surface defects are repaired;

[0011] Step 4, fine forging: heat the heating furnace to 700-800℃ to load the billet into the furnace, raise the temperature to 850-950℃, keep the temperature for 2-3h, take it out of the furnace and stretch it on the fine forging machine. After stretching, the diameter of the billet is 95-105mm, and the total deformation is 40-60%. The billet is finely forged and the surface defects are repaired;

[0012] Step 5, continuous rolling: the bar billet after fine forging is heated to 840-920°C by electromagnetic induction heating, and the temperature is kept for 5-10 minutes, and then rolled in a continuous rolling unit, and water-cooled to room temperature. The diameter of the round wire billet after rolling is 7.5-15 mm;

[0013] Step 6: Drawing: Drawing the rolled wire blank at room temperature, with each drawing deformation of 5 to 20%;

[0014] Step 7: Solution treatment: subject the drawn wire to high temperature solution treatment at a temperature of 750-880°C for 30-120 minutes, followed by water cooling to room temperature.

[0015] Step 8: Drawing: Drawing the wire after solution treatment at room temperature, with a deformation of 5 to 20% per drawing pass and a total deformation of 20 to 35%;

[0016] Step 9: Stripping: Use a mold to strip the drawn wire, with a stripping amount of more than 0.5 mm;

[0017] Step 10, polishing: polish the peeled wire, the surface roughness Ra of the polished wire is ≤1.2μm, and the out-of-roundness is ≤0.01mm;

[0018] Step 11: Coating: The polished wire is coated with a coating having a thickness of 1 to 15 μm.

[0019] The method for preparing large-disk round wire of TB9 titanium alloy for blind rivets, preferably, in the step 1, the process of preparing the ingot is: sponge titanium, aluminum beans, aluminum-vanadium master alloy, molybdenum-vanadium-aluminum-titanium master alloy, pure chromium particles, sponge zirconium, iron powder and titanium dioxide are mixed and pressed into electrodes, and subjected to vacuum consumable arc melting for not less than 3 times to obtain a cylindrical TB9 titanium alloy ingot with a diameter of 550-650 mm, and an alloy phase transition point of 750±10°C; preferably, the Al element content is controlled at 3.25-3.75wt%, the V element content is controlled at 7.75-8.25wt%, the Cr element content is controlled at 5.75-6.25wt%, the Mo element content is controlled at 3.75-4.25wt%, the Zr element content is controlled at 3.75-4.25wt%, the Fe element content is controlled at 0.08-0.20wt%, and the O element content is controlled at 0.06-0.12wt%.

[0020] In the method for preparing the large-scale round wire of TB9 titanium alloy for blind rivets, preferably, in the step 2, the blank forging is free forging, the holding temperature is 1125-1175° C., and the total deformation is 72-78%.

[0021] In the method for preparing the large-scale round wire of TB9 titanium alloy for blind rivets, preferably, in the step three, the rough forging is free forging, the holding temperature is 1025-1075° C., and the total deformation is 75-85%.

[0022] The method for preparing the TB9 titanium alloy large round wire for blind rivets is preferably such that in step 4, the fine forging temperature is 875-925° C., the total deformation is 45-55%, the cut length is 4500-5500 mm, and the weight is 150-250 kg.

[0023] The method for preparing the large coiled round wire of TB9 titanium alloy for blind rivets is preferably such that in step five, the continuous rolling temperature is 860-900°C, the total deformation is greater than or equal to 97%, the post-rolling cooling method is water cooling to room temperature, and the weight of the coiled round wire blank after rolling is 150-250kg.

[0024] In the method for preparing the TB9 titanium alloy large round wire for blind rivets, preferably, in step six, the amount of drawing deformation in each pass is 5-15%.

[0025] The method for preparing the large-scale round wire of TB9 titanium alloy for blind rivets is preferably such that in step seven, the solution temperature is 770 to 820° C. and the holding time is 60 to 120 min.

[0026] In the method for preparing the large-scale round wire of TB9 titanium alloy for blind rivets, preferably, in the step eight, the amount of deformation in each drawing pass is 5-15%, and the total deformation is 20-30%.

[0027] The method for preparing the large-scale round wire of TB9 titanium alloy for blind rivets, preferably, in the step eleven, the surface of the wire is coated with a coating made of a mixture of MoS2 and graphite, and the TB9 titanium alloy wire obtained after coating weighs 150 to 250 kg and has a diameter of 2.5 to 12.5 mm.

[0028] The design concept of the present invention is:

[0029] The method of the invention first obtains a TB9 titanium alloy ingot with a diameter of 500-700 mm, then forges the TB9 titanium alloy ingot at 1100-1200° C. into a rod blank with a diameter of 290-310 mm, then roughly forges the TB9 titanium alloy rod blank at 1000-1100° C. into a rod blank with a diameter of 130-150 mm, then fine forges the TB9 titanium alloy rod blank at 850-950° C. into a rod blank with a diameter of 95-105 mm, then continuously rolls the TB9 titanium alloy rod blank at 780-900° C., quenches after rolling to obtain a large round wire blank with a diameter of 7.5-15 mm, then draws at room temperature, then performs high-temperature solid solution, then draws again at room temperature, and then performs peeling, polishing and coating treatment. Thus, through the overall technical solution of the present invention, the cross-sectional structure of the alloy is a fine, uniform, equiaxed β-grain structure, the longitudinal section structure is an elongated fibrous structure, the surface is in a lubricating coating state, the wire coil weight is greater than 100kg, and after aging treatment, it has excellent strength and plasticity, meeting the requirements of TB9 titanium alloy materials for blind rivets.

[0030] The advantages and beneficial effects of the present invention are:

[0031] (1) In the composition design of the present invention, the Al element content is controlled at 3.25-3.75wt%, the V element content is controlled at 7.75-8.25wt%, the Cr element content is controlled at 5.75-6.25wt%, the Mo element content is controlled at 3.75-4.25wt%, the Zr element content is controlled at 3.75-4.25wt%, the Fe element content is controlled at 0.08-0.20wt%, the O element content is controlled at 0.06-0.12wt%, and the phase transition point is controlled at 750±10°C, which can effectively improve the strength of the TB9 titanium alloy in the solid solution aged state and have good plasticity.

[0032] (2) The total deformation of continuous rolling in the present invention is greater than or equal to 97%, the continuous rolling temperature is controlled, and the continuous rolling large deformation mode is used. The microstructure of the TB9 titanium alloy after rolling is a fine, uniform, equiaxed β grain structure.

[0033] (3) The present invention can obtain a large single weight TB9 titanium alloy wire for blind rivets with uniform microstructure, excellent surface quality and excellent dimensional tolerance through continuous rolling, room temperature drawing and peeling processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a microstructure photograph of the cross section of the TB9 titanium alloy wire with a diameter of φ6 mm obtained in Example 1.

[0035] Figure 2 This is a microstructure photograph of the longitudinal section of the TB9 titanium alloy wire with a diameter of φ6 mm obtained in Example 1. DETAILED DESCRIPTION

[0036] In the specific implementation process, the present invention provides a method for preparing a high-quality microstructure TB9 titanium alloy large single weight round wire for a blind rivet, which is specifically implemented in the following steps:

[0037] Step 1, ingot preparation: Sponge titanium, aluminum beans, aluminum-vanadium master alloy, molybdenum-vanadium-aluminum-titanium master alloy, pure chromium particles, sponge zirconium, iron powder and titanium dioxide are mixed and pressed into electrodes, and subjected to vacuum consumable arc melting for not less than 3 times to obtain a TB9 titanium alloy cylindrical ingot with a diameter of 500 to 700 mm (preferably 550 to 650 mm);

[0038] The TB9 titanium alloy ingot is composed of the following elements in weight percentage: Al 3.00-4.00% (preferably 3.25-3.75%), V 7.50-8.50% (preferably 7.75-8.25%), Cr 5.50-6.50% (preferably 5.75-6.25%), Mo 3.50-4.50% (preferably 3.75-4.25%), Zr 3.50-4.50% (preferably 3.75-4.25%), Fe≤0.30% (preferably 0.08-0.20%), O≤0.14% (preferably 0.06-0.12%), C≤0.05%, N≤0.03%, H≤0.03%, Y≤0.005%, the total of impurity elements≤0.40%, the balance is Ti (alloy phase transition point is 750±10°C);

[0039] Step 2, blank forging: heat the box-type industrial resistance furnace to 850-950°C, heat it to 1100-1200°C (the holding temperature is 350-450°C above the phase change point, preferably 1125-1175°C), keep it for 2-3 hours, take it out of the furnace and stretch it on a free forging machine. After stretching, the diameter of the bar billet is 290-310mm, the total deformation is 70-80% (preferably 72-78%), and the surface defects are repaired;

[0040] Step 3, rough forging: heat the heating furnace to 800-900°C to load the billet, raise the temperature to 1000-1100°C (the holding temperature is 250-350°C above the phase change point, preferably 1025-1075°C), hold for 2-3 hours, take it out of the furnace and stretch it on a free forging machine, the diameter of the billet after stretching is 130-150mm, the total deformation is 70-90% (preferably 75-85%), the weight is 150-250kg, and the billet after rough forging is obtained, and the surface defects are repaired;

[0041] Step 4, fine forging: heat the box-type industrial resistance furnace to 700-800°C to load the bar blank into the furnace, raise the temperature to 850-950°C (the insulation temperature is 100-200°C above the phase change point, preferably 875-925°C), keep the temperature for 2-3h, take it out of the furnace and stretch it on the fine forging machine, the diameter of the bar blank after stretching is 95-105mm, the total deformation is 40-60% (preferably 45-55%), cut it into a length of about 4500-5500mm, and weigh 150-250kg to obtain the bar blank after fine forging, and grind the surface defects;

[0042] Step 5, continuous rolling: using electromagnetic induction heating to heat the fine forged bar billet to 840-920°C (the holding temperature is 90-170°C above the phase transition point, preferably 860-900°C), the holding time is 5-10min, and then rolling in a continuous rolling mill, water cooling to room temperature, the weight of the rolled round wire billet is 150-250kg, the diameter is 7.5-15mm, and the total rolling deformation is greater than or equal to 97%;

[0043] Step 6: Drawing: Drawing the rolled wire blank at room temperature, with each drawing deformation amount being 5-20% (preferably 5-15%);

[0044] Step 7, solid solution: subject the drawn wire to high temperature solid solution for 30 to 120 minutes (preferably 60 to 120 minutes), the solid solution temperature is 750 to 880°C (the insulation temperature is 0 to 130°C above the phase transition point, preferably 770 to 820°C), and then water-cooled to room temperature;

[0045] Step 8, drawing: drawing the wire after solution treatment at room temperature, with each drawing deformation of 5-20% (preferably 5-15%) and a total deformation of 20-35% (preferably 20-30%);

[0046] Step 9: Peeling: Use a mold to peel the annealed wire, and the peeling amount is more than 0.5mm;

[0047] Step 10, polishing: polish the peeled wire, the surface roughness Ra of the polished wire is ≤1.2μm, and the out-of-roundness is ≤0.01mm;

[0048] Step 11: Coating treatment: The polished wire is coated with a coating having a thickness of 1 to 15 μm. The obtained TB9 titanium alloy wire has a weight of 150 to 250 kg and a diameter of 2.5 to 12.5 mm.

[0049] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0050] Example 1

[0051] In this embodiment, a method for preparing a large-scale round wire of TB9 titanium alloy for blind rivets comprises the following steps:

[0052] Step 1: Mix and press titanium sponge, aluminum beans, aluminum-vanadium master alloy, molybdenum-vanadium-aluminum-titanium master alloy, pure chromium particles, zirconium sponge, iron powder and titanium dioxide into 26 electrodes of 100 kg, and then melt them by vacuum consumable arc for three times to obtain 2600 kg TB9 titanium alloy ingots with an ingot size of about φ600mm×1900mm. The composition of the TB9 titanium alloy ingot is as follows (wt%): Al 3.48, V 8.06, Cr 5.92, Mo 4.06, Zr 3.85, Fe 0.13, O 0.082, C 0.010, N0.0084, H 0.016, and the balance is Ti (alloy phase transition point is 750°C);

[0053] Step 2: Forging the blank. Heat the box-type industrial resistance furnace to 900℃ and heat it to 1150℃. Keep the temperature at 400℃ above the phase change point for 3h. Take it out of the furnace and stretch it on a free forging machine (such as a 10MN fast hydraulic forging machine). After stretching, the diameter of the blank is φ300mm, the forging deformation is 75%, and the surface defects are ground until the surface is bright (without cracks and oxide scale).

[0054] Step 3, rough forging, heat the box-type industrial resistance furnace to 850℃, heat it to 1050℃, keep it at 300℃ above the phase change point, keep it for 2.5h, take it out of the furnace and stretch it on the free forging machine, the diameter of the rod after stretching is 140mm, the length is about 2800mm, the rough forging deformation is 78%, the weight is 205kg, and the surface defects are ground until the surface is bright (without cracks and oxide scale);

[0055] Step 4, fine forging, heat the box-type industrial resistance furnace to 750℃, heat it to 920℃, keep it at 170℃ above the phase change point, keep it for 2.5h, take it out of the furnace and stretch it on the fine forging machine, the diameter of the rod after stretching is 100mm, the fine forging deformation is 50%, cut it into a length of about 5300mm, weigh 200kg, and grind the surface defects until the surface is bright (without cracks and oxide scale);

[0056] Step 5, continuous rolling, using induction heating to heat the bar billet after fine forging to 880°C, the holding temperature is 130°C above the phase change point, the holding time is 5 minutes, and then rolling in a continuous rolling unit, and water cooling to room temperature after rolling. After rolling, the weight of the round wire billet is 196kg, the diameter is 10mm, and the rolling deformation is 99%;

[0057] Step 6: Drawing: Drawing the rolled wire blank at room temperature for five times, with a diameter of φ7.5 mm after drawing, and a drawing deformation of about 10% in each time, with a total deformation of 43.75%;

[0058] Step 7: Solution treatment: Solution treatment of the drawn wire at 780°C, with the holding temperature being 30°C above the phase transition point, for 120 minutes, and then cooling to room temperature with water;

[0059] Step 8: Drawing: The wire after solutionizing is drawn twice at room temperature, and the diameter after drawing is φ6.5mm. The drawing deformation of each drawing is about 10%, and the total deformation is 25%;

[0060] Step 9: peeling: peel the drawn wire to obtain a wire with a diameter of φ6 mm and a peeling amount of 0.5 mm;

[0061] Step 10: Polishing: after polishing, the surface roughness of the wire is Ra 0.8 μm and the out-of-roundness is 0.001 mm;

[0062] Step 11: coating the polished wire with a coating made of a mixture of MoS2 and graphite, with a coating thickness of 6 μm. The coating composition of this embodiment is as follows by weight percentage: 30% MoS2, 40% graphite, and the rest is a resin binder.

[0063] like Figure 1 As shown in the figure, the cross-section microstructure photo of TB9 titanium alloy wire with a diameter of φ6mm shows that the microstructure is fine and uniform equiaxed β grains.

[0064] like Figure 2 As shown in the figure, the longitudinal section microstructure photo of TB9 titanium alloy wire with a diameter of φ6mm, the microstructure is elongated β grains.

[0065] Example 2

[0066] In this embodiment, a method for preparing a large-scale round wire of TB9 titanium alloy for blind rivets comprises the following steps:

[0067] Step 1: Mix and press titanium sponge, aluminum beans, aluminum-vanadium master alloy, molybdenum-vanadium-aluminum-titanium master alloy, pure chromium particles, zirconium sponge, iron powder and titanium dioxide into 26 electrodes of 100 kg, and then melt them by vacuum consumable arc for three times to obtain 2600 kg TB9 titanium alloy ingots with an ingot size of about φ600mm×1900mm. The composition of the TB9 titanium alloy ingot is as follows (wt%): Al 3.44, V 8.02, Cr 6.04, Mo 4.08, Zr 3.85, Fe 0.08, O 0.079, C 0.0092, N0.0073, H 0.008, and the balance is Ti (alloy phase transition point is 750°C);

[0068] Step 2: Forging the blank. Heat the box-type industrial resistance furnace to 900℃ and heat it to 1150℃. Keep the temperature at 400℃ above the phase change point for 3h. Take it out of the furnace and stretch it on a free forging machine (such as a 10MN fast hydraulic forging machine). After stretching, the diameter of the blank is φ300mm, the forging deformation is 75%, and the surface defects are ground until the surface is bright (without cracks and oxide scale).

[0069] Step 3, rough forging, heat the box-type industrial resistance furnace to 850℃, heat it to 1050℃, keep it at 300℃ above the phase change point, keep it for 2.5h, take it out of the furnace and stretch it on the free forging machine, the diameter of the rod after stretching is 140mm, the length is about 2800mm, the rough forging deformation is 78%, the weight is 205kg, and the surface defects are ground until the surface is bright (without cracks and oxide scale);

[0070] Step 4, fine forging, heat the box-type industrial resistance furnace to 750℃, heat it to 890℃, keep it at 140℃ above the phase change point, keep it for 2.5h, take it out of the furnace and stretch it on the fine forging machine, the diameter of the rod after stretching is 100mm, the fine forging deformation is 50%, cut it into a length of about 5300mm, weigh 200kg, and grind the surface defects until the surface is bright (without cracks and oxide scale);

[0071] Step 5, continuous rolling, using induction heating to heat the bar billet after fine forging to 880°C, the holding temperature is 130°C above the phase change point, the holding time is 5 minutes, and then rolling in a continuous rolling unit, and water cooling to room temperature after rolling. After rolling, the weight of the round wire billet is 196kg, the diameter is 10mm, and the rolling deformation is 99%;

[0072] Step 6: Drawing: Drawing the rolled wire blank at room temperature for five times, with a diameter of φ7.5 mm after drawing, and a drawing deformation of about 10% in each time, with a total deformation of 43.75%;

[0073] Step 7: Solution treatment: Solution treatment of the drawn wire at 780°C, with the holding temperature being 30°C above the phase transition point, for 120 minutes, and then cooling to room temperature with water;

[0074] Step 8: Drawing: The wire after solutionizing is drawn twice at room temperature, and the diameter after drawing is φ6.5mm. The drawing deformation of each drawing is about 10%, and the total deformation is 25%;

[0075] Step 9: peeling: peel the drawn wire to obtain a wire with a diameter of φ6 mm and a peeling amount of 0.5 mm;

[0076] Step 10: Polishing: after polishing, the surface roughness of the wire is Ra 0.8 μm and the out-of-roundness is 0.001 mm;

[0077] Step 11: coating the polished wire with a coating made of a mixture of MoS2 and graphite, with a coating thickness of 6 μm. The coating composition of this embodiment is as follows by weight percentage: 30% MoS2, 40% graphite, and the rest is a resin binder.

[0078] The AMS4957F standard requires that the mechanical properties of TB9 titanium alloy wire should be 1276-1413MPa after aging at 482-566°C for 6-10 hours, the elongation should be greater than 10%, and the cross-sectional shrinkage should be greater than 20%. The TB9 titanium alloy wire obtained in Examples 1-2 was subjected to aging heat treatment at 550°C / 10h / AC (air cooling to room temperature), and the mechanical properties of the TB9 titanium alloy obtained in Examples 1-2 after aging were measured with reference to the national standard GB / T 228.1-2021 "Metallic Materials-Tensile Tests, Part I, Room Temperature Test Methods", and the test results are shown in Table 1.

[0079] Table 1

[0080]

[0081] From the mechanical property test results of Examples 1 and 2 after aging in Table 1, it can be seen that the yield strength can reach 1174-1201MPa, the tensile strength can reach 1291-1317MPa, the elongation can reach 16.5-17.5%, and the cross-sectional shrinkage can reach 33-39%. Therefore, the mechanical properties of Examples 1 and 2 after aging meet the performance requirements of the TB9 titanium alloy in the AMS4957F standard.

[0082] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing TB9 titanium alloy large round wire for blind rivets, characterized in that: The specific steps are as follows: Step 1, prepare ingot: take TB9 titanium alloy ingot with a diameter of 500-700 mm, and the composition of TB9 titanium alloy ingot is as follows by weight percentage: Al 3.00-4.00%, V 7.50-8.50%, Cr 5.50-6.50%, Mo 3.50-4.50%, Zr 3.50-4.50%, Fe≤0.30%, O≤0.14%, C≤0.05%, N≤0.03%, H≤0.03%, Y≤0.005%, the total of impurity elements ≤0.40%, and the balance is Ti; Step 2, billet forging: heat the heating furnace to 850-950℃ to load the ingot, raise the temperature to 1100-1200℃, keep the temperature for 2-3h, and stretch the billet on the forging machine. After stretching, the diameter of the billet is 290-310mm, the total deformation is 70-80%, and the surface defects are repaired; Step 3, rough forging: heat the heating furnace to 800-900℃ to load the billet, raise the temperature to 1000-1100℃, keep it at temperature for 2-3h, take it out of the furnace and stretch it on the forging machine. After stretching, the diameter of the billet is 130-150mm, and the total deformation is 70-90%. The billet is rough forged and the surface defects are repaired; Step 4, fine forging: heat the heating furnace to 700-800℃ to load the billet into the furnace, raise the temperature to 850-950℃, keep the temperature for 2-3h, take it out of the furnace and stretch it on the fine forging machine. After stretching, the diameter of the billet is 95-105mm, and the total deformation is 40-60%. The billet is finely forged and the surface defects are repaired; Step 5, continuous rolling: the bar billet after fine forging is heated to 840-920°C by electromagnetic induction heating, and the temperature is kept for 5-10 minutes, and then rolled in a continuous rolling unit, and water-cooled to room temperature. The diameter of the round wire billet after rolling is 7.5-15 mm; Step 6: Drawing: Drawing the rolled wire blank at room temperature, with each drawing deformation of 5 to 20%; Step 7: Solution treatment: subject the drawn wire to high temperature solution treatment at a temperature of 750-880°C for 30-120 minutes, followed by water cooling to room temperature. Step 8: Drawing: Drawing the wire after solution treatment at room temperature, with a deformation of 5 to 20% per drawing pass and a total deformation of 20 to 35%; Step 9: Stripping: Use a mold to strip the drawn wire, with a stripping amount of more than 0.5 mm; Step 10, polishing: polish the peeled wire, the surface roughness Ra of the polished wire is ≤1.2μm, and the out-of-roundness is ≤0.01mm; Step 11: Coating: The polished wire is coated with a coating having a thickness of 1 to 15 μm.

2. The preparation method according to claim 1, characterized in that: Preferably, in the step one, the process of preparing the ingot is: sponge titanium, aluminum beans, aluminum-vanadium master alloy, molybdenum-vanadium-aluminum-titanium master alloy, pure chromium particles, sponge zirconium, iron powder and titanium dioxide are mixed and pressed into electrodes, and subjected to vacuum consumable arc melting for not less than 3 times to obtain a cylindrical TB9 titanium alloy ingot with a diameter of 550 to 650 mm, and an alloy phase transition point of 750 ± 10 ° C; preferably, the Al element content is controlled at 3.25 to 3.75wt%, the V element content is controlled at 7.75 to 8.25wt%, the Cr element content is controlled at 5.75 to 6.25wt%, the Mo element content is controlled at 3.75 to 4.25wt%, the Zr element content is controlled at 3.75 to 4.25wt%, the Fe element content is controlled at 0.08 to 0.20wt%, and the O element content is controlled at 0.06 to 0.12wt%.

3. The preparation method according to claim 1, characterized in that: Preferably, in the step 2, the blank forging is free forging, the holding temperature is 1125-1175° C., and the total deformation is 72-78%.

4. The preparation method according to claim 1, characterized in that: Preferably, in step three, the rough forging is free forging, the holding temperature is 1025-1075° C., and the total deformation is 75-85%.

5. The preparation method according to claim 1, characterized in that: Preferably, in step 4, the fine forging temperature is 875-925° C., the total deformation is 45-55%, the cut length is 4500-5500 mm, and the weight is 150-250 kg.

6. The preparation method according to claim 1, characterized in that: Preferably, in step five, the continuous rolling temperature is 860-900° C., the total deformation is greater than or equal to 97%, the cooling method after rolling is water cooling to room temperature, and the weight of the coil round wire billet after rolling is 150-250 kg.

7. The preparation method according to claim 1, characterized in that: Preferably, in step six, the amount of deformation in each drawing pass is 5-15%.

8. The preparation method according to claim 1, characterized in that: Preferably, in step seven, the solution temperature is 770-820° C., and the holding time is 60-120 min.

9. The preparation method according to claim 1, characterized in that: Preferably, in step eight, the amount of deformation in each drawing pass is 5-15%, and the total deformation is 20-30%.

10. The preparation method according to claim 1, characterized in that: Preferably, in the step eleven, the surface of the wire is coated with a coating made of a mixture of MoS2 and graphite, and the TB9 titanium alloy wire obtained after coating weighs 150 to 250 kg and has a diameter of 2.5 to 12.5 mm.

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