Preparation method of TC16 titanium alloy large-piece-weight disc round wire for fastener

Abstract

The invention relates to the technical field of processing of titanium alloy wires for fasteners, in particular to a preparation method of a TC16 titanium alloy large-piece-weight disc round wire for a fastener. Firstly, a TC16 titanium alloy cast ingot is obtained, and the TC16 titanium alloy cast ingot is prepared from, by weight, 2.20%-3.80% of Al, 4.50%-5.50% of Mo, 4.00%-5.00% of V, smaller than or equal to 0.25% of Fe, smaller than or equal to 0.15% of O, smaller than or equal to 0.10% of C, smaller than or equal to 0.05% of N, smaller than or equal to 0.012% of H, smaller than or equal to 0.30% of the sum of impurity elements and the balance Ti; then, the TC16 titanium alloy cast ingot is subjected to cogging forging, rough forging, precision forging and continuous rolling in sequence to be rolled into a large-piece-weight disc round wire with the diameter being 7.5-15 mm; and drawing, annealing, peeling, polishing and coating are carried out. Therefore, the cross section structure of the obtained alloy is a fine and uniform equiaxial alpha + beta double-phase structure, and the alloy has excellent strength and plasticity and meets the requirements of TC16 titanium alloy materials for fasteners.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy wire processing for fasteners, and in particular to a method for preparing a TC16 titanium alloy large single weight round wire for fasteners. Background Art

[0002] TC16 titanium alloy is a martensitic α+β two-phase high-strength titanium alloy, with a β-phase stabilization coefficient of about 0.83, close to the critical composition. It is the main titanium alloy fastener material used by the Russian aerospace sector. TC16 alloy can be heat-treated and strengthened, and the vacuum solution treatment temperature is only 800℃, 150℃ lower than TC4 alloy. After solution aging treatment, the alloy can reach a strength of more than 1030MPa, and is less sensitive to stress concentration caused by notches and deflections.

[0003] TC16 titanium alloy has good mechanical properties, excellent cold forming ability, and the fastener processing process can achieve continuous processing and other obvious advantages, and the future development and application prospects are very broad. However, at present, most of the TC16 titanium alloy wires used for domestic fasteners are processed in small batches, mainly straight strips and small round wires weighing less than 30KG. The consistency of product quality is difficult to guarantee, resulting in large fluctuations in the mechanical properties of the prepared fasteners, 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 TC16 titanium alloy wire (specification Φ3~15mm, single coil weight ≥100kg) to prepare high-quality and high-uniformity large single weight coiled TC16 titanium alloy wire. Summary of the invention

[0005] Based on this, it is necessary to address the above technical problems. The present invention provides a method for preparing TC16 titanium alloy large single weight round wire for fasteners. The prepared TC16 titanium alloy wire 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 TC16 titanium alloy large single weight round wire for fasteners, the specific steps are as follows:

[0008] Step 1, prepare ingot: take TC16 titanium alloy ingot with a diameter of 500-700 mm, and the composition of TC16 titanium alloy ingot is as follows by weight percentage: Al 2.20-3.80%, Mo 4.50-5.50%, V 4.00-5.00%, Fe≤0.25%, O≤0.15%, C≤0.10%, N≤0.05%, H≤0.012%, the total of impurity elements ≤0.30%, 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 warm for 2-3 hours, take out of the furnace and stretch on the forging machine, the diameter of the billet after stretching is 290-310mm, the total deformation is 70-80%, sawing, and grinding surface defects;

[0010] Step 3, rough forging: heat the heating furnace to 800-900℃ to load the billet, raise the temperature to 1000-1100℃, keep it warm for 2-3 hours, 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 it warm for 2-3 hours, 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 after fine forging is obtained, and the surface defects are repaired;

[0012] Step 5, continuous rolling: the bar billet after fine forging is heated to 780-840°C by electromagnetic induction heating, kept at this temperature for 4-6 minutes, and then rolled in a continuous rolling unit, and the diameter of the round wire billet after rolling is 7.5-15 mm;

[0013] Step 6: Drawing: warm drawing the rolled wire blank at a temperature of 700-780°C, with a deformation of 5-20% per drawing pass and a total deformation of 5%-60%;

[0014] Step 7: Annealing: Use a heat treatment furnace to anneal the drawn wire at a temperature of 720-780°C for 1-3 hours, cool the furnace to 550°C, and then air cool.

[0015] Step 8: Peeling: peeling the annealed wire;

[0016] Step 9, polishing: polish the peeled wire, the surface roughness Ra of the polished wire is ≤1.2μm, and the out-of-roundness is ≤0.01mm;

[0017] Step 10: Coating: The polished wire is coated with a coating having a thickness of 1 to 15 μm.

[0018] In the step 1, the process of preparing the ingot is: sponge titanium, aluminum beans, molybdenum-vanadium-aluminum-titanium master alloy, aluminum-vanadium master alloy and titanium dioxide are mixed and pressed into electrodes, and subjected to vacuum consumable arc melting for no less than 3 times to obtain a TC16 titanium alloy cylindrical ingot with a diameter of 550 to 650 mm, and the alloy phase transition point is 850±10°C.

[0019] In the step 2, the blank forging is free forging, the holding temperature is 1125-1175° C., and the total deformation is 72-78%.

[0020] In the step 3, the rough forging is free forging, the holding temperature is 1025-1075° C., and the total deformation is 75-85%.

[0021] In the step 4, the finishing forging temperature is 875-925° C., the total deformation is 45-55%, the cut length is 4500-5500 mm, and the weight is 150-200 kg.

[0022] In the step 5, the continuous rolling temperature is 790-830° C., and the total deformation is greater than or equal to 95%.

[0023] In the step six, the warm drawing temperature is 720-760° C., the deformation amount of each drawing pass is 5-15%, and the total deformation amount is 20%-40%.

[0024] In the step seven, the annealing temperature is 740-760° C., and the annealing time is 2-2.5 hours.

[0025] In the step eight, the peeling is performed by a mold, and the peeling amount is greater than 0.5 mm.

[0026] In the step ten, the surface of the wire is coated with a coating made of a mixture of MoS2 and graphite, and the coating thickness after coating is 1 to 15 μm. The obtained TC16 titanium alloy wire weighs 150 to 200 kg and has a diameter of 3 to 15 mm.

[0027] The design concept of the present invention is:

[0028] The method of the present invention first obtains a TC16 titanium alloy ingot with a diameter of 500-700 mm, then forges the TC16 titanium alloy ingot at 1100-1200° C. into a rod blank with a diameter of 290-310 mm, then rough forges the TC16 titanium alloy rod blank at 1000-1100° C. into a rod blank with a diameter of 130-150 mm, then fine forges the TC16 titanium alloy rod blank at 850-950° C. into a rod blank with a diameter of 95-105 mm, and then continuously rolls the TC16 titanium alloy rod blank at 750-850° C. into a large single-weight round wire with a diameter of 7.5-15 mm, and then undergoes drawing, annealing, peeling, polishing and coating. Thus, the cross-sectional structure of the alloy obtained by the overall technical solution of the present invention is a fine, uniform, equiaxed α+β dual-phase structure, which has excellent strength and plasticity and meets the requirements of TC16 titanium alloy materials for fasteners.

[0029] The advantages and beneficial effects of the present invention are:

[0030] (1) In the composition design of the present invention, the Al element content is controlled at 2.80-3.20wt%, the Mo element content is controlled at 4.75-5.25wt%, the V element content is controlled at 4.25-4.75wt%, the O element content is controlled at 0.05-0.15wt%, and the phase transition point is controlled at 850±10°C, which can effectively improve the strength of TC16 titanium alloy while having good plasticity.

[0031] (2) The total deformation of continuous rolling in the present invention is greater than or equal to 95%, the continuous rolling temperature is controlled, and the continuous rolling large deformation mode is used. The microstructure of the TC16 titanium alloy after rolling is a fine, uniform, equiaxed dual-phase structure.

[0032] (3) The present invention can obtain a large single weight TC16 titanium alloy wire for fasteners with uniform microstructure, excellent surface quality and excellent dimensional tolerance through continuous rolling and warm drawing processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a microstructure photograph of the TC16 titanium alloy rod with a diameter of 7 mm obtained in Example 1.

[0034] Figure 2 This is a microstructure photograph of the TC16 titanium alloy rod with a diameter of Φ8mm obtained in Example 2.

[0035] Figure 3 This is a microstructure photograph of the TC16 titanium alloy rod with a diameter of Φ10 mm obtained in Example 3.

[0036] Figure 4 This is a microstructure photograph of the TC16 titanium alloy rod with a diameter of Φ7mm obtained in Comparative Example 1. DETAILED DESCRIPTION

[0037] In the specific implementation process, the present invention provides a method for preparing a high-quality microstructure TC16 titanium alloy large single weight round wire for fasteners, which is specifically implemented in the following steps:

[0038] Step 1, ingot preparation: Sponge titanium, aluminum beans, molybdenum-vanadium-aluminum-titanium master alloy, aluminum-vanadium master alloy 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 TC16 titanium alloy cylindrical ingot with a diameter of 500-700 mm (preferably 550-650 mm).

[0039] The TC16 titanium alloy ingot is composed of the following elements in weight percentage: Al 2.20-3.80% (preferably 2.80-3.20%), Mo 4.50-5.50% (preferably 4.75-5.25%), V 4.00-5.00% (preferably 4.25-4.75%), Fe≤0.25%, O≤0.15% (preferably 0.08-0.15%), C≤0.10%, N≤0.05%, H≤0.012%, other single impurity elements (including Cu, Mg, Ca, Si, etc.)≤0.10%, the total impurity elements≤0.30%, and the balance is Ti (the alloy phase transition point is 850±10°C);

[0040] 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 250-350°C above the phase change point, preferably 1125-1175°C), keep it warm 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 blank is Φ290-310mm, the forging deformation is 70-80% (preferably 72-78%), sawing, and grinding the surface defects until its surface is bright (without cracks and oxide scale);

[0041] Step 3, rough forging: heat the box-type industrial resistance furnace to 800-900°C, heat it to 1000-1100°C (the holding temperature is 150-250°C above the phase change point, preferably 1025-1075°C), keep it warm for 2-3 hours, take it out of the furnace and stretch it on a free forging machine. After stretching, the diameter of the rod billet is 130-150mm, the rough forging deformation is 70-90% (preferably 75-85%), the weight is 150-200kg, and the surface defects are repaired until the surface is bright (without cracks and oxide scale);

[0042] Step 4, fine forging: heat the box-type industrial resistance furnace to 700-800°C, heat it to 850-950°C (the holding temperature is 0-100°C above the phase change point, preferably 875-925°C), keep it warm for 2-3 hours, take it out of the furnace and stretch it on the fine forging machine, the diameter of the rod after stretching is 95-105mm, the fine forging deformation is 40-60% (preferably 45-55%), cut it into a length of 4500-5500mm, weigh 150-200kg, and grind the surface defects until its surface is bright (without cracks and oxide scale);

[0043] Step 5, continuous rolling: the bar billet after fine forging is heated to 780-840°C by induction heating (the holding temperature is 10-70°C below the phase change point, preferably 790-830°C), kept warm for 4-6 minutes, and then rolled in a continuous rolling mill. After rolling, the weight of the round wire billet is 150-200kg, the diameter is 7.5-15mm, and the deformation is greater than or equal to 95%;

[0044] Step 6, drawing: drawing temperature 700-780°C (holding temperature is 70-150°C below the phase transition point, preferably 720-760°C), each drawing deformation is 5-20% (preferably 5-15%), and the total deformation is 5%-60%;

[0045] Step 7, annealing: annealing temperature is 720-780°C (holding temperature is 70-130°C below the phase transition point, preferably 740-760°C), keep warm for 1-3 hours (preferably 2-2.5 hours), furnace cool to 550°C and then air cool;

[0046] Step 8: Peeling: peel the annealed wire, with the peeling amount being greater than 0.5 mm;

[0047] Step 9: Polishing: After polishing, the surface roughness of the wire is Ra≤1.2μm, and the out-of-roundness is ≤0.01mm;

[0048] Step 10: Coating: The polished wire is coated with a coating having a thickness of 1 to 15 μm.

[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 TC16 titanium alloy large single weight round wire for fasteners comprises the following steps:

[0052] Step 1, ingot preparation: Sponge titanium, aluminum beans, molybdenum-vanadium-aluminum-titanium master alloy, aluminum-vanadium master alloy and titanium dioxide are mixed and pressed into 26 electrodes of 100 kg, and after three vacuum consumable arc melting, 2600 kg TC16 titanium alloy ingots are obtained, and the ingot size is about Φ600mm×2000mm. The TC16 titanium alloy ingot is composed of the following elements in weight percentage: Al 3.00, Mo 5.00, V 4.50, Fe 0.10, O 0.10, C 0.003, N 0.002, H 0.001, and the balance is Ti (alloy phase transition point is 850℃);

[0053] Step 2, billet forging: heat the box-type industrial resistance furnace to 900℃, heat it to 1150℃, keep it at 300℃ above the phase change point, keep it for 3 hours, take it out of the furnace and stretch it on a free forging machine (such as 10MN fast hydraulic forging machine). After stretching, the diameter of the billet is Φ300mm, the forging deformation is 75%, sawing, and grinding the surface defects 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 warm for 2.5 hours, take it out of the furnace and stretch it on the free forging machine. After stretching, the diameter of the bar billet is 140mm, the rough forging deformation is 78%, the weight is 196kg, 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 900℃, keep it warm for 2.5 hours, take it out of the furnace and stretch it on the fine forging machine. The diameter of the rod billet after stretching is 100mm, the fine forging deformation is 50%, the length is 5000mm, the weight is 185kg, and the surface defects are repaired until the surface is bright (without cracks and oxide scale);

[0056] Step 5, continuous rolling: the bar billet after fine forging is heated to 800°C by induction heating, kept at this temperature for 5 minutes, and then rolled in a continuous rolling unit. After rolling, the weight of the round wire billet is 180kg, the diameter is 9mm, and the rolling deformation is 99.19%;

[0057] Step 6: Drawing: drawing temperature is 740℃, 110℃ below the phase transition point, three drawing passes, the diameter after drawing is Φ7.6mm, the drawing deformation of each pass is about 10%, and the total deformation is about 29%;

[0058] Step 7: Annealing: 740℃ annealing for 2 hours, furnace cooling to 550℃ and then air cooling;

[0059] Step 8, peeling: peel the annealed wire to obtain a wire with a diameter of Φ7mm and a peeling amount of 0.6mm;

[0060] Step 9: Polishing: After polishing, the surface roughness of the wire is Ra0.4μm and the out-of-roundness is 0.006mm;

[0061] Step 10: Coating: The polished wire is coated with a coating made of a mixture of MoS2 and graphite, with a coating thickness of 10 μm. By weight percentage, MoS2 35%, graphite 40%, and the rest is a resin binder.

[0062] like Figure 1 As shown in the figure, the microstructure photo of TC16 titanium alloy wire with a diameter of Φ7mm shows that the microstructure is a fine and uniform equiaxed dual-phase structure.

[0063] Example 2

[0064] In this embodiment, a method for preparing a TC16 titanium alloy large single weight round wire for fasteners comprises the following steps:

[0065] Step 1, ingot preparation: Sponge titanium, aluminum beans, molybdenum-vanadium-aluminum-titanium master alloy, aluminum-vanadium master alloy and titanium dioxide are mixed and pressed into 26 electrodes of 100 kg, and after three vacuum consumable arc melting, 2600 kg TC16 titanium alloy ingots are obtained, and the ingot size is about Φ600mm×2000mm. The TC16 titanium alloy ingot is composed of the following elements in weight percentage: Al 3.00, Mo 5.00, V 4.50, Fe 0.10, O 0.10, C 0.003, N 0.002, H 0.001, and the balance is Ti (alloy phase transition point is 850℃);

[0066] Step 2, billet forging: heat the box-type industrial resistance furnace to 900℃, heat it to 1150℃, keep it at 300℃ above the phase change point, keep it for 3 hours, take it out of the furnace and stretch it on a free forging machine (such as 10MN fast hydraulic forging machine). After stretching, the diameter of the billet is Φ300mm, the forging deformation is 75%, sawing, and grinding the surface defects until the surface is bright (without cracks and oxide scale);

[0067] Step 3, rough forging: heat the box-type industrial resistance furnace to 850℃, heat it to 1050℃, keep it warm for 2.5 hours, take it out of the furnace and stretch it on the free forging machine. After stretching, the diameter of the bar billet is 140mm, the rough forging deformation is 78%, the weight is 194kg, and the surface defects are repaired until the surface is bright (without cracks and oxide scale);

[0068] Step 4, fine forging: heat the box-type industrial resistance furnace to 750℃, heat it to 900℃, keep it warm for 2.5 hours, take it out of the furnace and stretch it on the fine forging machine. The diameter of the rod billet after stretching is 100mm, the fine forging deformation is 50%, the length is 5000mm, the weight is 184kg, and the surface defects are repaired until the surface is bright (without cracks and oxide scale);

[0069] Step 5, continuous rolling: the bar billet after fine forging is heated to 790°C by induction heating, kept at this temperature for 5 minutes, and then rolled in a continuous rolling mill. The weight of the rolled round wire billet is 179kg, the diameter is 10mm, and the rolling deformation is 99%;

[0070] Step 6: Drawing: drawing temperature is 740℃, 110℃ below the phase transition point, three drawing passes, the diameter after drawing is Φ8.6mm, the drawing deformation of each pass is about 10%, and the total deformation is 26%;

[0071] Step 7: Annealing: 740℃ annealing for 2 hours, furnace cooling to 550℃ and then air cooling;

[0072] Step 8, peeling: peel the annealed wire to obtain a wire with a diameter of Φ8mm and a peeling amount of 0.6mm;

[0073] Step 9: Polishing: After polishing, the surface roughness of the wire is Ra0.4μm and the out-of-roundness is 0.006mm;

[0074] Step 10: Coating: The polished wire is coated with a coating made of a mixture of MoS2 and graphite, with a coating thickness of 8 μm. By weight percentage, MoS2 35%, graphite 40%, and the rest is a resin binder.

[0075] like Figure 2 As shown in the figure, the microstructure photo of TC16 titanium alloy wire with a diameter of Φ8mm shows that the microstructure is a fine and uniform equiaxed dual-phase structure.

[0076] Example 3

[0077] In this embodiment, a method for preparing a TC16 titanium alloy large single weight round wire for fasteners comprises the following steps:

[0078] Step 1, ingot preparation: Sponge titanium, aluminum beans, molybdenum-vanadium-aluminum-titanium master alloy, aluminum-vanadium master alloy and titanium dioxide are mixed and pressed into 26 electrodes of 100 kg, and after three vacuum consumable arc melting, 2600 kg TC16 titanium alloy ingots are obtained, and the ingot size is about Φ600mm×2000mm. The TC16 titanium alloy ingot is composed of the following elements in weight percentage: Al 3.00, Mo 5.00, V 4.50, Fe 0.10, O 0.10, C 0.003, N 0.002, H 0.001, and the balance is Ti (alloy phase transition point is 850℃);

[0079] Step 2, billet forging: heat the box-type industrial resistance furnace to 900℃, heat it to 1150℃, keep it at 300℃ above the phase change point, keep it for 3 hours, take it out of the furnace and stretch it on a free forging machine (such as 10MN fast hydraulic forging machine). After stretching, the diameter of the billet is Φ300mm, the forging deformation is 75%, sawing, and grinding the surface defects until the surface is bright (without cracks and oxide scale);

[0080] Step 3, rough forging: heat the box-type industrial resistance furnace to 850℃, heat it to 1050℃, keep it warm for 2.5 hours, take it out of the furnace and stretch it on the free forging machine. After stretching, the diameter of the rod billet is 140mm, the rough forging deformation is 78%, the weight is 192kg, and the surface defects are ground until the surface is bright (without cracks and oxide scale);

[0081] Step 4, fine forging: heat the box-type industrial resistance furnace to 750℃, heat it to 900℃, keep it warm for 2.5 hours, take it out of the furnace and stretch it on the fine forging machine. The diameter of the rod billet after stretching is 100mm, the fine forging deformation is 50%, the length is 5000mm, the weight is 182kg, and the surface defects are ground until the surface is bright (without cracks and oxide scale);

[0082] Step 5, continuous rolling: the bar billet after fine forging is heated to 810°C by induction heating, kept at this temperature for 5 minutes, and then rolled in a continuous rolling unit. The weight of the rolled round wire billet is 178kg, the diameter is 12mm, and the rolling deformation is 98.56%;

[0083] Step 6: Drawing: drawing temperature 740℃, 110℃ below the phase transition point, three drawing passes, diameter after drawing Φ10.6mm, each drawing deformation is about 7%, and the total deformation is 22%;

[0084] Step 7: Annealing: 740℃ annealing for 2 hours, furnace cooling to 550℃ and then air cooling;

[0085] Step 8, peeling: peel the annealed wire to obtain a wire with a diameter of Φ10mm and a peeling amount of 0.6mm;

[0086] Step 9: Polishing: After polishing, the surface roughness of the wire is Ra0.4μm and the out-of-roundness is 0.006mm;

[0087] Step 10: Coating: The polished wire is coated with a coating made of a mixture of MoS2 and graphite, with a coating thickness of 6 μm. By weight percentage, MoS2 35%, graphite 40%, and the rest is a resin binder.

[0088] like Figure 3 As shown in the figure, the microstructure photo of TC16 titanium alloy wire with a diameter of Φ10mm shows that the microstructure is a fine and uniform equiaxed dual-phase structure.

[0089] Comparative Example 1

[0090] Compared with Example 2, the difference between Comparative Example 2 and Example 2 is that the annealing temperature of Comparative Example 1 in step 7 is 900° C., and the rest of the process and conditions are the same as those of Example 1.

[0091] like Figure 4 As shown in the microstructure photo of the TC16 titanium alloy rod with a diameter of Φ7mm obtained in Comparative Example 1, Figure 4 It can be seen that the microstructure has grain boundary α phase, coarse grains, and lamellar structure inside. The microstructure does not meet the requirements of "TC16 titanium alloy rod and wire for cold heading 11-CL-145A" for the microstructure of TC16 titanium alloy.

[0092] With reference to the national standard GB / T 228.1-2010 “Metallic materials - Tensile tests, Part 1, Room temperature test methods”, the mechanical properties of the TC16 titanium alloy bars obtained in Examples 1 to 3 were measured respectively. The test results are shown in Table 1.

[0093] Yield strength / MPa Tensile strength / MPa Elongation / % Sectional shrinkage / % Example 1 837 860 27 67 Example 2 791 825 25 65 Example 3 788 822 24.5 69 Comparative Example 1 777 886 11.5 29

[0094] As can be seen from the results of Examples 1 to 3 in Table 1, the yield strength can reach 788 to 837 MPa, the tensile strength can reach 822 to 860 MPa, the elongation can reach 24.5 to 27%, and the cross-sectional shrinkage can reach 65 to 69%. Therefore, the mechanical properties of Examples 1 to 3 are within the performance requirements of the TC16 titanium alloy in the standard "TC16 titanium alloy rod and wire for cold heading 11-CL-145A", that is, the tensile strength is 815 to 930 MPa, the elongation is ≥14%, and the cross-sectional shrinkage is ≥65%, which meets the requirements of the TC16 titanium alloy for fasteners.

[0095] The above description is only an implementation mode of the present invention, and does not limit the protection scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the protection scope of the present invention.

Claims

1. A method for preparing a TC16 titanium alloy large single weight round wire for fasteners, characterized in that: The specific steps are as follows: Step 1, prepare ingot: take TC16 titanium alloy ingot with a diameter of 500-700 mm, and the composition of TC16 titanium alloy ingot is as follows by weight percentage: Al 2.20-3.80%, Mo 4.50-5.50%, V 4.00-5.00%, Fe≤0.25%, O≤0.15%, C≤0.10%, N≤0.05%, H≤0.012%, the total of impurity elements ≤0.30%, 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 warm for 2-3 hours, take out of the furnace and stretch on the forging machine, the diameter of the billet after stretching is 290-310mm, the total deformation is 70-80%, sawing, and grinding surface defects; Step 3, rough forging: heat the heating furnace to 800-900℃ to load the billet, raise the temperature to 1000-1100℃, keep it warm for 2-3 hours, 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 it warm for 2-3 hours, 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 after fine forging is obtained, and the surface defects are repaired; Step 5, continuous rolling: the bar billet after fine forging is heated to 780-840°C by electromagnetic induction heating, kept at this temperature for 4-6 minutes, and then rolled in a continuous rolling unit, and the diameter of the round wire billet after rolling is 7.5-15 mm; Step 6: Drawing: warm drawing the rolled wire blank at a temperature of 700-780°C, with a deformation of 5-20% per drawing pass and a total deformation of 5%-60%; Step 7: Annealing: Use a heat treatment furnace to anneal the drawn wire at a temperature of 720-780°C for 1-3 hours, cool the furnace to 550°C, and then air cool. Step 8: Peeling: peeling the annealed wire; Step 9, 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 10: 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 step one, the process of preparing the ingot is: sponge titanium, aluminum beans, molybdenum-vanadium-aluminum-titanium intermediate alloy, aluminum-vanadium intermediate alloy and titanium dioxide are mixed and pressed into electrodes, and subjected to vacuum consumable arc melting for no less than 3 times to obtain a TC16 titanium alloy cylindrical ingot with a diameter of 550 to 650 mm, and the alloy phase transition point is 850±10°C.

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 150-200 kg.

6. The preparation method according to claim 1, characterized in that: Preferably, in step five, the continuous rolling temperature is 790-830° C., and the total deformation is greater than or equal to 95%.

7. The preparation method according to claim 1, characterized in that: Preferably, in step six, the warm drawing temperature is 720-760° C., the deformation amount of each drawing pass is 5-15%, and the total deformation amount is 20%-40%.

8. The preparation method according to claim 1, characterized in that: Preferably, in step seven, the annealing temperature is 740-760° C., and the annealing time is 2-2.5 hours.

9. The preparation method according to claim 1, characterized in that: Preferably, in step eight, the peeling is performed by mold peeling, and the peeling amount is greater than 0.5 mm.

10. The preparation method according to claim 1, characterized in that: Preferably, in the step ten, the surface of the wire is coated with a coating made of a mixture of MoS2 and graphite, the coating thickness after coating is 1 to 15 μm, and the obtained TC16 titanium alloy wire weighs 150 to 200 kg and has a diameter of 3 to 15 mm.

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