Preparation method and application of a titanium alloy coil wire resistant to 650 °C high temperature

Abstract

The present invention belongs to the technical field of titanium alloy processing, and relates to a preparation method and application of a titanium alloy coil wire capable of withstanding a high temperature of 650 °C. For a prefabricated wire blank with designed chemical composition and microstructure, it is first heated by a combination of an induction heater and a tube furnace, and continuously rolled by a continuous rolling mill arranged horizontally and vertically. By designing pass parameters, induction heating and heat compensation between stands, controlling the reduction per pass and the cumulative reduction, a wire blank A with a ten-sided cross-section whose structure and dimensions meet the requirements is obtained; then it is heated by a combination of an induction heater and a tube furnace, and hot drawn by a two-roll die to obtain a wire blank B with a circular cross-section; then it is heated by a combination of an induction heater and a tube furnace, the heating temperature is controlled, and it is skived with a skiving die to obtain a wire with precise dimensions. Finally, it is polished with a belt polishing machine to obtain the target titanium alloy coil wire. The target titanium alloy coil wire can be applied to high-temperature fasteners in hypersonic aircraft, aeroengines or space engines.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloy processing, relates to high-temperature titanium alloy coil wire, and specifically relates to a preparation method and application of a 650°C high-temperature resistant titanium alloy coil wire. Background Art

[0002] When hypersonic aircraft operate in a thermal environment of 500°C to 650°C, they face severe performance challenges. Not only must the body strength be ensured, the aerodynamic shape be maintained, reusable and lightweight designs be achieved, but also in key parts such as the fuselage skin and aerodynamic leading edge, high-temperature titanium alloys are mostly used instead of superalloys for structural components and fasteners to achieve weight reduction and high-temperature resistance design.

[0003] However, currently, the domestic research on high-temperature resistant titanium alloy fasteners is relatively scarce. For existing mature high-temperature titanium alloy wires, the upper limit of their temperature resistance generally does not exceed 600°C, making it difficult to meet the requirement of 650°C temperature resistance for high-temperature titanium alloy wires used in fasteners of new hypersonic aircraft. Therefore, high-temperature alloys with a greater specific gravity can only be forcedly selected for the wires used in fasteners of new hypersonic aircraft. However, the thermal expansion coefficients of high-temperature alloys and titanium alloys differ by nearly a factor of two, and there are also significant differences in thermal conductivity; under the action of thermal shock, the resulting thermal mismatch stress will seriously affect the service life of the fasteners, leading to premature connection failure and posing a great threat to the service safety of the aircraft. Therefore, it is extremely urgent to develop a wire for high-temperature titanium alloy fasteners with a temperature resistance level of 650°C.

[0004] There are two types of wires for fasteners: straight bars and coils; compared with straight bar wires, coil wires have advantages such as good tissue consistency, high material utilization rate, and high upsetting efficiency. Currently, titanium alloy coil wires are usually prepared by a drawing process; however, for high-temperature titanium alloys with a temperature resistance of 650°C, they have high high-temperature strength and low plasticity. If drawing is carried out with a large deformation amount, surface cracks are extremely likely to occur, resulting in an increase in subsequent surface removal amount and a reduction in the finished product rate of the wire; when using the traditional fixed die hot drawing method, there are problems such as large drawing deformation resistance, easy scratching of the die, and easy cracking of the wire; in addition, high-temperature titanium alloy hot drawing deformation requires a relatively high heating temperature, while the heating efficiency of traditional tube furnaces is relatively low, making it difficult to meet the requirements of high-efficiency production.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide a preparation method and application of a 650°C high-temperature resistant titanium alloy coil wire to solve the problems of surface cracking during drawing, low finished product rate, and large die wear in the processing technology of existing high-temperature titanium alloy coil wires.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A preparation method of a titanium alloy coil wire resistant to high temperature of 650 °C comprises the following steps:

[0009] Step 1: A wire blank A is rolled by a continuous rolling mill arranged horizontally and vertically;

[0010] Step 2: The wire blank A is subjected to hot sizing and rounding treatment by a roll die to obtain a wire blank B;

[0011] Step 3: The wire blank B is subjected to finish hot peeling and polishing treatment to obtain the target titanium alloy coil wire.

[0012] Specifically, the rolling process in Step 1 is as follows:

[0013] First, a prefabricated wire blank is heated by an induction heater combined with a tube furnace, and then the heated prefabricated wire blank is continuously rolled by a continuous rolling mill arranged horizontally and vertically. The cumulative deformation amount during the continuous rolling process is 48.37% - 77.56%; the induction heater is arranged between the stands of the continuous rolling mill to ensure the consistency of the final rolling temperature.

[0014] Further, the induction heater is a high - frequency induction heater, the heating frequency is 20 kHz - 70 kHz, and the heating temperature is 850 °C - 950 °C; the heating temperature of the tube furnace is 900 °C - 1010 °C; the temperature after rolling by each stand of the continuous rolling mill is 900 °C - 1010 °C.

[0015] Specifically, the pass used by the continuous rolling mill is a same - shaped pass; preferably, the pass is a ten - square pass, and the central angle α corresponding to each side of the ten - square pass is 36°. The chamfer of the current pass is (1 / 4 - 1 / 3)d0, where d0 is the diameter of the equivalent circular area after rolling by the current pass. The height H of the current pass can ensure that the cross - sectional area after rolling is approximately equal to the equivalent circular area (the area difference is less than or equal to 8%).

[0016] Further, during the continuous rolling process, the reduction of the last pass is 5% - 14%, and the reduction of each of the remaining passes is 9% - 14%.

[0017] Specifically, the specific process of Step 2 is as follows:

[0018] First, the obtained wire blank A is subjected to induction heating, then heated by a tube furnace after induction heating, and finally drawn by a two - stage roll die (the pass is an ellipse - round pass); among them,

[0019] The induction heating uses a high - frequency induction heater, the heating frequency is 20 kHz - 70 kHz, the induction heating temperature is 850 °C - 910 °C, and the heating temperature of the tube furnace is 950 °C - 1010 °C;

[0020] The reduction per pass of the double-roll die drawing is 12.89% - 19.56%, and the temperature after drawing is greater than or equal to 900 °C.

[0021] Specifically, in step 3, before the hot skin removal of the wire blank B into a finished product, the wire blank B is heated by an induction heater and a tube furnace; where

[0022] The induction heater is a high-frequency induction heater, and the heating frequency of the high-frequency induction heater is 20 kHz - 70 kHz, and the heating temperature is 840 °C - 900 °C; the heating temperature of the tube furnace is 900 °C - 960 °C.

[0023] Furthermore, in step 3, a sand belt polishing machine is used for polishing to ensure that the surface roughness Ra ≤ 1.6 μm.

[0024] Specifically, by mass percentage, the composition of each element in the prefabricated wire blank is as follows: Al: 5.3% - 6.5%, Mo: 0.3% - 0.8%, Nb: 0.2% - 0.7%, Sn: 3.0% - 4.5%, Ta: 0.5% - 3.0%, Zr: 3.2% - 5.2%, W: 0.9% - 2.4%, C: 0.03% - 0.08%, Si: 0.2% - 0.5%, Fe ≤ 0.01%, H ≤ 0.005%, N ≤ 0.02, O: 0.06% - 0.10%, and the rest is Ti and unavoidable impurities; the β transformation temperature of this alloy is 1030 °C - 1060 °C. Among them, to improve the thermal stability and surface oxidation resistance of the alloy, the content of O element is precisely controlled (0.06% - 0.10%); and, the content of W element is 0.9% - 2.4%. Increasing the content of W element can significantly increase the high-temperature yield strength and tensile strength of this alloy. At the same time, the total content of impurity elements such as Fe, Ni, Cr, V, Cu, H, and N is strictly controlled not to exceed 0.1% to improve the creep resistance and endurance performance.

[0025] In addition, the present invention also provides an application of a 650 °C high-temperature resistant titanium alloy coiled wire. The 650 °C high-temperature resistant titanium alloy coiled wire prepared by the above partial or all preparation methods is applied to fasteners in high-temperature parts such as hypersonic aircraft, aero-engines, and space engines.

[0026] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0027] 1) The present invention focuses on the preparation of high-temperature titanium alloy coil wire and the characteristics of microstructure control. A continuous rolling mill arranged horizontally and vertically is selected to carry out the rolling of wire blanks. By designing pass parameters, controlling the rolling heating temperature, controlling the cumulative rolling deformation, controlling the pass deformation, and increasing induction heating, the rolling temperature is effectively controlled. On the one hand, the control of the post-rolling microstructure is achieved, and on the other hand, the problem of rolling cracks caused by low rolling temperature and excessive deformation resistance is avoided.

[0028] 2) The present invention adopts roller die hot drawing. Roller die drawing uses a deformation method combining drawing and rolling, avoiding the problems of easy die scratching and surface cracking of wire caused by large deformation resistance when using traditional fixed die to hot draw high-temperature titanium alloy wire.

[0029] 3) The present invention uses induction heating combined with a tube furnace heating (induction heating has high efficiency, and tube furnace heating is uniform). It not only improves the heating efficiency of high-temperature titanium alloy but also realizes temperature uniformity, effectively reducing the thickness of the surface oxide layer and pollution layer introduced during the heating process, reducing the surface cracking tendency of high-temperature titanium alloy wire caused by the surface oxide layer, and improving the peeling efficiency of high-temperature titanium alloy wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings herein are incorporated into the specification and form a part of this specification, and are used together with the specification to explain the principles of the present invention. To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art.

[0031] Figure 1 It is a flow chart of a method for preparing a 650°C high-temperature resistant titanium alloy coil wire provided by the present invention;

[0032] Figure 2 It is a transverse microstructure diagram of the prefabricated wire blank provided by the present invention;

[0033] Figure 3 It is a rolling pass diagram of the continuous rolling mill provided by the present invention;

[0034] Figure 4 It is a physical diagram of wire blank A during the preparation of the coil wire in Example 1 of the present invention;

[0035] Figure 5 It is a physical diagram of wire blank B during the preparation of the coil wire in Example 1 of the present invention;

[0036] Figure 6 It is a physical photo of the finished product after peeling during the preparation of the coil wire in Example 1 of the present invention;

[0037] Figure 7 It is a high-magnification transverse microstructure diagram of the target titanium alloy coil wire prepared in Example 1 of the present invention;

[0038] Figure 8 It is the transverse high-magnification microstructure diagram of the target titanium alloy coil wire prepared in Example 2 of the present invention;

[0039] Figure 9 It is the transverse high-magnification microstructure diagram of the target titanium alloy coil wire prepared in Example 3 of the present invention

[0040] Figure 10 It is the high-magnification microstructure diagram of the coil wire prepared in Example 1 of the present invention after solution aging heat treatment;

[0041] Figure 11 It is the high-magnification microstructure diagram of the coil wire prepared in Example 2 of the present invention after solution aging heat treatment;

[0042] Figure 12 It is the high-magnification microstructure diagram of the coil wire prepared in Example 3 of the present invention after solution aging heat treatment. Specific embodiments

[0043] Here, the exemplary embodiments will be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. On the contrary, they are merely examples consistent with some aspects of the present invention detailed in the appended claims.

[0044] See Figure 1 , this embodiment provides a method for preparing a 650 °C high-temperature resistant titanium alloy coil wire, which specifically includes the following steps:

[0045] Step 1: Roll the prefabricated wire blank with a horizontal and vertical rolling mill to obtain wire blank A:

[0046] Among them, the prefabricated wire blank is a coiled wire blank obtained by designing the chemical composition and microstructure; by mass percentage, the composition of each element in the prefabricated wire blank is as follows: Al: 5.3% - 6.5%, Mo: 0.3% - 0.8%, Nb: 0.2% - 0.7%, Sn: 3.0% - 4.5%, Ta: 0.5% - 3.0%, Zr: 3.2% - 5.2%, W: 0.9% - 2.4%, C: 0.03 - 0.08%, Si: 0.2% - 0.5%, Fe ≤ 0.01%, H ≤ 0.005%, N ≤ 0.02, O: 0.06% - 0.10%, and the rest is Ti and unavoidable impurities; its transverse structure is a uniform and fine α + β structure, specifically see Figure 2 ;

[0047] Furthermore, the β transformation temperature of the high-temperature resistant titanium alloy provided in this embodiment is 1030°C to 1060°C, and the transverse structure is a uniform and fine α+β structure. The prefabricated wire billet used for rolling is heated by a high-frequency induction heater, the heating frequency is 20 kHz to 70 kHz, and the temperature of the induction heater is 850°C to 950°C; after induction heating, it is uniformly heated by a tube furnace, the heating temperature is 900°C to 1010°C, and then the heated prefabricated wire billet is subjected to hot continuous rolling by a hot continuous rolling mill with a flat-vertical arrangement of ten-square pass. See Figure 3 . Among them, the central angle α corresponding to each pass side is 36°, the pass chamfer is (1 / 4 to 1 / 3)d0, d0 is the diameter of the equivalent circular area after rolling of this pass, and the pass height H should ensure that the cross-sectional area after rolling is approximately equal to the equivalent circular area (the area difference does not exceed 8%). Induction heaters are arranged between the hot continuous rolling stands, and the temperature after rolling of each stand is controlled between 900°C and 1010°C by the rolling speed and the induction heating temperature. During the continuous rolling process, the pass reduction of the last pass is 5% to 14%, and the reduction of each of the remaining passes is 9% to 14%. The cumulative reduction of hot continuous rolling is 48.37% to 77.56%, and a wire billet with a ten-square cross-section is obtained after rolling.

[0048] Step 2: Perform roll die hot sizing and rounding on the wire billet A to obtain wire billet B:

[0049] The ten-square cross-section wire billet A obtained in Step 1 is first heated by a high-frequency induction heater, the heating frequency is 20 kHz to 70 kHz, and the heating temperature is 850°C to 910°C; after induction heating, it is uniformly heated by a tube furnace, and the tube furnace heating temperature is 950°C to 1010°C; finally, drawing is performed using a two-pass roll die with an elliptical-round pass, the pass reduction is 12.89% to 19.56%, and the temperature after drawing is greater than or equal to 900°C.

[0050] Step 3: Perform finished product hot skin pass and polishing on the wire billet B to obtain the target high-temperature resistant titanium alloy coil wire:

[0051] The wire billet B is heated by a high-frequency induction heater, the heating frequency is 20 kHz to 70 kHz, and the heating temperature is 840°C to 900°C. After induction heating, it is heated by a tube furnace, and the heating temperature of the tube furnace is 900°C to 960°C. It is skinned with a skin pass die, and after skin passing, it is polished with a sand belt polishing machine, and the surface roughness Ra ≤ 1.6 μm;

[0052] Through the above three steps, a high-temperature resistant titanium alloy coil wire with surface, structure, room temperature performance and high-temperature performance all meeting the requirements can be prepared.

[0053] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0054] Example 1 (Φ8.5mm wire)

[0055] This example provides a method for preparing a titanium alloy coil wire resistant to high temperature of 650 °C, which specifically includes the following steps:

[0056] Step 1: Roll the prefabricated wire blank with a continuous rolling mill arranged horizontally and vertically to obtain wire blank A:

[0057] Among them, the prefabricated wire blank is a coiled wire blank designed by designing the chemical composition and microstructure; by mass percentage, the composition of each element in the prefabricated wire blank is as follows: Al: 5.3%, Mo: 0.3%, Nb: 0.7%, Sn: 4.5%, Ta: 0.5%, Zr: 4.0%, W: 2.4%, C: 0.03 - 0.05%, Si: 0.20 - 0.25%, Fe ≤ 0.01%, H ≤ 0.005%, N ≤ 0.02, O: 0.10%, and the rest is Ti and unavoidable impurities;

[0058] Furthermore, the prefabricated wire blank (Φ13.5mm) used for rolling in this example is heated by a high-frequency induction heater, the heating frequency is 20 kHz - 70 kHz, and the heating temperature is 850 °C; after induction heating, it is uniformly heated by a tubular heating furnace, the heating temperature is 900 °C, and the heated prefabricated wire blank is placed on a hot continuous rolling mill arranged horizontally and vertically, and hot continuous rolling is carried out with a ten-square pass. Among them, the central angle α corresponding to each pass side is 36°, the pass chamfer is 1 / 3d0, d0 is the diameter of the equivalent circular area after rolling of this pass, and the pass height H should ensure that the cross-sectional area after rolling and the equivalent circular area are approximately equal (the area difference does not exceed 7%). Induction heaters are arranged between the hot continuous rolling mills, and the temperature after rolling of each mill is controlled between 900 °C and 950 °C by the rolling speed and the induction heating temperature. The deformation amount of each pass (excluding the deformation amount of the last pass of rolling) is controlled within the range of 9% - 14%, the deformation amount of the last pass of continuous rolling is 5%, and the cumulative deformation amount during the hot continuous rolling process is 48.37%. After rolling, a wire blank A with a ten-square cross-section (equivalent circle Φ9.7mm) is obtained.

[0059] Step 2: Perform roller die hot drawing and sizing on the wire blank A to obtain wire blank B:

[0060] The wire blank A with a decagonal cross-section obtained in Step 1 is first heated by a high-frequency induction heater at a heating frequency of 20 kHz to 70 kHz and a heating temperature of 850°C. After induction heating, it is uniformly heated by a tube furnace at a tube furnace heating temperature of 950°C. Finally, it is drawn using a two-stage roll die with an elliptical-round hole profile to obtain a wire blank B with a diameter of Φ8.7 mm, a deformation rate of 19.56%, and the temperature after drawing is greater than or equal to 900°C.

[0061] Step 3: After subjecting the wire blank B to finish hot skin-pass and polishing treatments, the target titanium alloy coil wire is obtained:

[0062] The wire blank B is heated by a high-frequency induction heater at a heating frequency of 20 kHz to 70 kHz and a heating temperature of 840°C. After induction heating, it is heated by a tube furnace with a heating temperature of 900°C. It is skinned to Φ8.5 mm using a skin-pass die, and after skin-passing, it is polished using a belt polishing machine with a surface roughness Ra ≤ 1.6 μm.

[0063] Example 2 (Φ5.0 mm wire)

[0064] This example provides a method for preparing a titanium alloy coil wire resistant to high temperatures of 650°C, which specifically includes the following steps:

[0065] Step 1: The prefabricated wire blank is rolled using a continuous rolling mill arranged horizontally and vertically to obtain a wire blank A:

[0066] Among them, the prefabricated wire blank is a coiled wire blank designed by designing the chemical composition and microstructure. By mass percentage, the composition of each element in the prefabricated wire blank is as follows: Al: 6.0%, Mo: 0.8%, Nb: 0.2%, Sn: 4.0%, Ta: 1.5%, Zr: 3.2%, W: 1.8%, C: 0.06 - 0.08%, Si: 0.30 - 0.35%, Fe ≤ 0.01%, H ≤ 0.005%, N ≤ 0.02, O: 0.08%, and the rest is Ti and unavoidable impurities;

[0067] Further, the prefabricated wire blank (Φ10mm) used for rolling in this embodiment is heated by a high-frequency induction heater with a heating frequency of 20 kHz to 70 kHz and the temperature of the induction heater is 890°C; after induction heating, it is uniformly heated by a tubular heating furnace with a heating temperature of 950°C, and the heated prefabricated wire blank is placed on a hot continuous rolling mill arranged horizontally and vertically, and hot continuous rolling is carried out using a ten-square pass. Among them, the central angle α corresponding to each pass side is 36°, the pass chamfer is 1 / 3d0, where d0 is the diameter of the equivalent circular area after rolling of this pass, and the pass height H should ensure that the cross-sectional area after rolling is approximately equal to the equivalent circular area (the area difference does not exceed 6%). Induction heaters are arranged between the hot continuous rolling stands, and the temperature after rolling of each stand is controlled between 950°C and 980°C by the rolling speed and the induction heating temperature. The deformation amount of each pass (excluding the deformation amount of the last pass) is controlled within the range of 9% to 14%, the deformation amount of the last pass of continuous rolling is 7%, the cumulative deformation amount of hot continuous rolling is 67.51%, and a wire blank A with a ten-square cross-section (equivalent circle Φ5.7mm) is obtained after rolling.

[0068] Step 2: Perform roll die hot sizing and rounding on the wire blank A to obtain wire blank B:

[0069] The wire blank A with a ten-square cross-section obtained in Step 1 is first heated by a high-frequency induction heater with a frequency of 20 kHz to 70 kHz and an induction heating temperature of 890°C; after induction heating, it is uniformly heated by a tubular heating furnace with a tubular heating temperature of 990°C; finally, it is drawn using a two-pass roll die with an elliptical-round pass to obtain a wire blank B with a diameter of Φ5.2mm, the deformation amount is 16.77%, and the temperature after drawing is greater than or equal to 900°C.

[0070] Step 3: Perform finish hot skin pass and polishing on the wire blank B to obtain the target titanium alloy coil wire:

[0071] The wire blank B is heated by a high-frequency induction heater with a frequency of 20 kHz to 70 kHz and an induction heating temperature of 880°C. After induction heating, it is heated by a tubular heating furnace with a heating temperature of 940°C. It is skinned to Φ5.0mm using a skin pass die, and after skin pass, it is polished using a belt polishing machine with a surface roughness Ra ≤ 1.6μm.

[0072] Example 3 (Φ4.0mm wire)

[0073] This embodiment provides a method for preparing a titanium alloy coil wire resistant to high temperature of 650°C, which specifically includes the following steps:

[0074] Step 1: Roll the prefabricated wire blank using a continuous rolling mill arranged horizontally and vertically to obtain wire blank A:

[0075] Among them, the prefabricated wire blank is a coiled wire blank obtained by designing the chemical composition and microstructure. By mass percentage, the elemental composition of the prefabricated wire blank is as follows: Al: 6.5%, Mo: 0.5%, Nb: 0.5%, Sn: 3.0%, Ta: 3.0%, Zr: 5.2%, W: 0.9%, C: 0.05 - 0.07%, Si: 0.45 - 0.5%, Fe ≤ 0.01%, H ≤ 0.005%, N ≤ 0.02, O: 0.06%, and the rest is Ti and unavoidable impurities;

[0076] Furthermore, the prefabricated wire blank (Φ9.5mm) used for rolling in this embodiment is heated by a high-frequency induction heater, the heating frequency is 20kHz - 70kHz, and the temperature of the induction heater is 950°C; after induction heating, it is uniformly heated by a tube furnace, the heating temperature is 1010°C, and the heated prefabricated wire blank is placed on a hot continuous rolling mill stand arranged horizontally and vertically, and hot continuous rolling is carried out with a ten-square pass. Among them, the central angle α corresponding to each pass side is 36°, the pass chamfer is 1 / 4d0, d0 is the diameter of the equivalent circular area after rolling of this pass, and the pass height H should ensure that the cross-sectional area after rolling is approximately equal to the equivalent circular area (the area difference does not exceed 5%). Induction heaters are arranged between the hot continuous rolling mill stands, the temperature after rolling of each stand is between 980°C and 1000°C, the deformation amount of each pass (excluding the deformation amount of the last pass) is controlled within the range of 9% - 14%, the deformation amount of the last pass of continuous rolling is 10%, the cumulative deformation amount of hot continuous rolling is 77.56%, and a wire blank A with a ten-square cross-section (equivalent circle Φ4.5mm) is obtained after rolling.

[0077] Step 2: Perform roll die hot sizing on the wire blank A to obtain wire blank B:

[0078] The wire blank A with a ten-square cross-section obtained in Step 1 is first heated by a high-frequency induction heater, the frequency is 20kHZ - 70kHZ, and the induction heating temperature is 910°C; after induction heating, it is uniformly heated by a tube furnace, and the tube furnace heating temperature is 1010°C; finally, a two-pass roll die with an elliptical-round pass is used for drawing to obtain a wire blank B with a diameter of Φ4.2mm, the pass deformation amount is 12.89%, and the temperature after drawing is greater than or equal to 900°C.

[0079] Step 3: After performing finished product hot skinning and polishing on the wire blank B, the target titanium alloy coil wire is obtained:

[0080] The wire blank B is heated by a high-frequency induction heater, the frequency is 20kHz - 70kHz, the induction heating temperature is 900°C, after induction heating, it is heated by a tube furnace, the heating temperature of the tube furnace is 960°C, it is skinned to Φ4.0mm with a skinning die, and after skinning, it is polished with a sand belt polishing machine, and the surface roughness Ra ≤ 1.6μm.

[0081] Through analysis, it can be seen that in the above Examples 1-3, the rolled wire blank A, the drawn wire blank B, and the target titanium alloy coil wire obtained by peeling and polishing are all highly efficient, stable, and free of cracking, and can meet the preparation requirements of the titanium alloy coil wire resistant to 650°C high temperature, with good process applicability. Taking Example 1 as an example, during the preparation process of the coil wire in Example 1 of the present invention, the physical pictures of the wire blank A, the wire blank B, and the finished product after peeling are corresponding Figure 4 , Figure 5 , Figure 6 as shown

[0082] To further verify whether the internal structures and properties of the titanium alloy wires resistant to 650°C high temperature prepared in the above Examples 1-3 meet the usage requirements of high temperature titanium alloys, specimens were cut from the wires of Φ8.5mm, Φ5.0mm, and Φ4.0mm respectively, and the room temperature and high temperature properties of the corresponding wires were tested:

[0083] ① Specimens were cut from the Φ8.5mm wire to test its room temperature and high temperature properties. After solution aging treatment, the test results are as follows: Its room temperature tensile strength is 1120MPa - 1185MPa, yield strength is 1022MPa - 1049MPa, elongation after fracture is 9.0% - 16.5%, reduction of area is 16% - 30%, and shear strength is 652MPa - 694MPa. At 650°C high temperature, its tensile strength is 630MPa - 675MPa, yield strength is 508MPa - 542MPa, elongation after fracture is 23.0% - 28.5%, and reduction of area is 26% - 48%. The residual strain measured at 650°C, 100MPa, and 100h is 0.137% - 0.187%; at 650°C, 200MPa, it did not fracture after 101h or more. After hot exposure of the 650°C blank at room temperature, the elongation is 5.7% - 8.3%, and the reduction of area is 7% - 16%.

[0084] ② Specimens were cut from the Φ5.0mm wire to test its room temperature and high temperature properties. After solution aging treatment, the test results are as follows: Its room temperature tensile strength is 1130MPa - 1192MPa, yield strength is 1019MPa - 1055MPa, elongation after fracture is 9.5% - 18.5%, reduction of area is 23% - 36%, and shear strength is 666MPa - 704MPa. At 650°C high temperature, its tensile strength is 633MPa - 684MPa, yield strength is 515MPa - 548MPa, elongation after fracture is 23.2% - 32.5%, and reduction of area is 28% - 45%. The residual strain measured at 650°C, 100MPa, and 100h is 0.148% - 0.192%; at 650°C, 200MPa, it did not fracture after 101h or more.

[0085] ③Samples were cut from Φ4.0mm wire rods to test their room temperature and high temperature properties. After solution aging treatment, the test results are as follows: The room temperature tensile strength is 1135MPa - 1196MPa, the yield strength is 1033MPa - 1059MPa, the elongation after fracture is 9.0% - 17.5%, the reduction of area is 18% - 32%, and the shear strength is 663MPa - 695MPa. At 650°C high temperature, the tensile strength is 642MPa - 687MPa, the yield strength is 512MPa - 563MPa, the elongation after fracture is 25.7% - 33.5%, and the reduction of area is 32% - 56%. The residual strain measured at 650°C, 100MPa, and 100h is 0.143% - 0.188%; at 650°C and 200MPa, it did not fracture after 101h or more.

[0086] Figures 7 - 9 They respectively correspond to the transverse high-magnification microstructures of the 650°C high-temperature resistant titanium alloy wire rods prepared in Example 1, Example 2, and Example 3 of the present invention; Figures 10 - 12 They respectively correspond to the high-magnification microstructures of the coiled wire rods prepared in Example 1, Example 2, and Example 3 of the present invention after solution aging heat treatment. It can be Figures 7 - 12 seen that for the target titanium alloy coiled wire rods prepared by the preparation method provided by the present invention, their grains are fine and evenly distributed, the phase distribution is uniform, and there are no obvious defects.

[0087] In summary, the applicant combined the above tests and analyzed the test results, and found that the 650°C high-temperature resistant titanium alloy coiled wire rods prepared by the present invention have good room temperature and high temperature properties, can meet the preparation requirements of 650°C high-temperature resistant titanium alloy fasteners, and have good application prospects.

[0088] The above are only specific embodiments of the present invention, which enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0089] It should be understood that the present invention is not limited to the above-described content and can be modified and changed without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A method for preparing a 650°C high temperature resistant titanium alloy coil wire, characterized in that: The following steps are involved: Step 1: rolling the prefabricated wire billet using a horizontal and vertical continuous rolling mill to obtain wire billet A; Step 2, performing roller die hot drawing and rounding treatment on the wire blank A to obtain wire blank B; Step 3, hot stripping and polishing the wire blank B to obtain the target titanium alloy coil wire; The rolling process of step 1 is as follows: firstly, the prefabricated wire billet is induction heated by an induction heater, then uniformly heated by a tubular heating furnace, and then the heated prefabricated wire billet is continuously rolled by a horizontally arranged continuous rolling mill, wherein the cumulative deformation during the continuous rolling process is 48.37% to 77.56%, and the hole type adopted by the continuous rolling mill is a ten-square hole type, and the central angle α corresponding to each ten-square hole type side is 36°; the induction heater is arranged between the racks of the continuous rolling mill; the induction heater adopts a high-frequency induction heater, the heating frequency is 20kHz to 70kHz, and the heating temperature is 850°C to 950°C; the heating temperature of the tubular heating furnace is 900°C to 1010°C; The specific process of step 2 is: firstly induction heating the obtained wire blank A, then heating it with a tubular heating furnace, and finally drawing it with a two-continuous roller die; wherein the induction heating adopts a high-frequency induction heater, the heating frequency is 20kHz to 70kHz, and the heating temperature is 850°C to 910°C; the heating temperature of the tubular heating furnace is 950°C to 1010°C; the deformation of the two-continuous roller die drawing pass is 12.89% to 19.56%, and the temperature after drawing is greater than or equal to 900°C; In step 3, before hot peeling the wire blank B, the wire blank B is first induction heated by an induction heater and then heated by a tubular heating furnace; wherein the induction heater is a high-frequency induction heater, and the heating frequency of the high-frequency induction heater is 20kHz to 70kHz, and the heating temperature is 840°C to 900°C; the heating temperature of the tubular heating furnace is 900°C to 960°C.

2. The method for preparing the 650°C high temperature resistant titanium alloy coil wire according to claim 1, characterized in that: The temperature of each stand of the continuous rolling mill after rolling is 900℃~1010℃.

3. The method for preparing the 650°C high temperature resistant titanium alloy coil wire according to claim 1, characterized in that: During the continuous rolling process, the deformation of the last pass is 5% to 14%, and the deformation of each of the remaining passes is 9% to 14%.

4. The method for preparing the 650°C high temperature resistant titanium alloy coil wire according to claim 1, characterized in that: In step 3, a belt polisher is used for polishing to ensure that the surface roughness Ra is ≤ 1.6 μm.

5. The method for preparing the 650°C high temperature resistant titanium alloy coil wire according to claim 1, characterized in that: In step 1, the composition of each element in the prefabricated wire blank is as follows, calculated by mass percentage: Al: 5.3% to 6.5%, Mo: 0.3% to 0.8%, Nb: 0.2% to 0.7%, Sn: 3.0% to 4.5%, Ta: 0.5% to 3.0%, Zr: 3.2% to 5.2%, W: 0.9% to 2.4%, C: 0.03% to 0.08%, Si: 0.2% to 0.5%, Fe≤0.01%, H≤0.005%, N≤0.02, O: 0.06% to 0.10%, and the rest is Ti and unavoidable impurities.

6. An application of a 650°C high temperature resistant titanium alloy coil wire, characterized in that: Application of 650°C high temperature resistant titanium alloy coil wire prepared by the preparation method according to any one of claims 1 to 5 in fasteners for hypersonic aircraft, aeroengines or aerospace engines.

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