Method for improving superplasticity of Ti65 high-temperature titanium alloy plate

Abstract

The application discloses a method for improving superplasticity of Ti65 high-temperature titanium alloy plate, which comprises the following steps: firstly, heat treating the Ti65 high-temperature titanium alloy plate in a muffle furnace; and then, hot-rolling the Ti65 high-temperature titanium alloy plate on a rolling mill. The Ti65 high-temperature titanium alloy plate is solid-solution treated in the muffle furnace at a temperature of 1050 DEG C for 120 min, and then water-cooled; then, the Ti65 high-temperature titanium alloy plate is aging treated in the muffle furnace at a temperature of 520 DEG C to 720 DEG C for 60 min to 80 min, and then air-cooled. Finally, the Ti65 high-temperature titanium alloy plate is polished on sandpaper to eliminate surface oxides, and Ti-1 antioxidant is uniformly coated on the surface of the Ti65 high-temperature titanium alloy plate to protect the Ti65 high-temperature titanium alloy plate from high-temperature oxidation. The Ti65 high-temperature titanium alloy plate prepared through the simple rolling and heat treatment process has excellent superplasticity, and the tensile elongation is up to 600% to 700%, so that the Ti65 high-temperature titanium alloy plate can meet the hot working forming requirement of complex-geometric-shape components and can fully realize the hot working forming of the complex-geometric-shape components in an airplane, and has good practicability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of Ti65 high-temperature titanium alloy preparation process, and particularly relates to a method for improving superplasticity of Ti65 high-temperature titanium alloy plate. BACKGROUND

[0002] High-temperature titanium alloys have broad application prospects in the field of aerospace structural lightweight due to their excellent comprehensive mechanical properties, high specific strength, heat resistance and creep resistance. At present, mature high-temperature titanium alloys applied in 600 ℃ environment have been systematically studied at home and abroad, but there are few reports on high-temperature titanium alloys with long-time service temperature of 650 ℃. With the rapid development of new high-performance supersonic / hypersonic aircraft, the forming requirements of high-performance key components with complex geometry in aircraft are becoming higher and higher. However, Ti65 high-temperature titanium alloy cannot get rid of the common shortcomings of titanium alloys, that is, narrow processing window and large deformation resistance, which shows that the poor forming characteristics of Ti65 high-temperature titanium alloy will bring great challenges to the manufacturing of complex geometry of key components.

[0003] Chinese patent CN109750185B provides a preparation method of 650 ℃ high-temperature titanium alloy sheet for superplastic forming. The method adopts hot rolling processing to obtain 650 ℃ titanium alloy sheet with excellent superplasticity. The preparation steps are as follows: (1) after heating, the 650 ℃ titanium alloy ingot is opened and forged to obtain titanium alloy plate blank for rolling; (2) after coating and heating, the obtained plate blank is opened and rolled on a rolling mill; (3) after heating, the plate blank is subjected to second rolling; (4) after heat treatment above the beta phase transition point, the plate blank is rapidly water quenched; (5) after heating, the plate blank is subjected to third hot rolling; (6) after heating, the plate blank is subjected to fourth reversing hot rolling; (7) the obtained blank is subjected to assembly welding to obtain a clad laminated package; (8) after heating, the laminated package is hot rolled to obtain a semi-finished plate; (9) the semi-finished plate is subjected to creep straightening, annealing, acid and alkali washing to obtain a 0.8-2.0 mm thick 650 ℃ titanium alloy sheet product.

[0004] However, the above method can obtain high-temperature titanium alloy sheet for superplastic forming through multiple hot rolling and annealing, which is complex and is not conducive to the hot working forming of key components with complex geometry in aircraft. Therefore, it is an important problem to be solved at present to design an excellent superplastic Ti65 high-temperature titanium alloy and improve the hot working performance of Ti65 high-temperature titanium alloy to meet the requirements of complex geometry manufacturing of key components in aircraft. SUMMARY

[0005] The purpose of the present application is to provide a method for improving the superplasticity of Ti65 high-temperature titanium alloy plate.

[0006] The application is mainly realized by the following technical solutions:

[0007] A method for improving the superplasticity of Ti65 high-temperature titanium alloy plate, comprising the following steps:

[0008] Step S1: cutting processing to obtain Ti65 high-temperature titanium alloy plate;

[0009] Step S2: heat treatment of the Ti65 high-temperature titanium alloy plate in a muffle furnace, and then hot rolling on a rolling mill;

[0010] Step S3: solid solution treatment of the Ti65 high-temperature titanium alloy plate in a muffle furnace at a temperature of 1050 DEG C for 120 min, and then water cooling;

[0011] Step S4: aging treatment of the Ti65 high-temperature titanium alloy plate in a muffle furnace at a temperature of 520 DEG C to 720 DEG C for 60 min to 80 min, and then air cooling;

[0012] Step S5: polishing the Ti65 high-temperature titanium alloy plate on sandpaper to eliminate surface oxides, and uniformly coating Ti-1 antioxidant on the surface of the Ti65 high-temperature titanium alloy plate to protect it from high-temperature oxidation.

[0013] In order to better realize the application, further, in the step S1, the as-cast Ti65 high-temperature titanium alloy with a purity of 99.9% is prepared by a vacuum induction levitation melting method.

[0014] In order to better realize the application, further, in the step S1, the Ti65 high-temperature titanium alloy is subjected to slow wire spark machining to obtain a Ti65 high-temperature titanium alloy plate with a thickness of 4.2 mm.

[0015] In order to better realize the application, further, in the step S2, the Ti65 high-temperature titanium alloy plate is kept in a muffle furnace at a temperature of 1150 DEG C for 60 min.

[0016] In order to better realize the application, further, in the step S2, the thickness is reduced by 0.05 mm for each pass of rolling to a final thickness of 1.2 mm.

[0017] In order to better realize the application, further, in the step S4, the Ti65 high-temperature titanium alloy plate is aged in a muffle furnace at a temperature of 600 DEG C for 70 min to 80 min.

[0018] In order to better realize the application, further, in the step S5, the treated Ti65 high-temperature titanium alloy plate has a superplastic elongation of 600% to 700% at 950 DEG C.

[0019] The beneficial effects of the present application are as follows:

[0020] The present application prepares the microstructure of Ti65 high-temperature titanium alloy by combining hot rolling and annealing. The Ti65 high-temperature titanium alloy plate prepared by the simple rolling and heat treatment process exhibits excellent superplasticity, and the tensile elongation is as high as 600% to 700%, which can meet the requirements of hot working forming of complex geometric parts, and the process is simple and efficient. Compared with the existing process, the superplasticity and hot working performance of the Ti65 high-temperature titanium alloy are significantly improved, which shows excellent industrial application value, and can fully realize the hot working forming of complex geometric parts in an airplane, and has good practicality. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic structural diagram of a tensile sample;

[0022] Figure 2 is a morphology diagram of tensile fracture of a sample after aging treatment at 550 DEG C for 60 min in Example 1;

[0023] Figure 3 is a morphology diagram of tensile fracture of a sample after aging treatment at 600 DEG C for 60 min in Example 2;

[0024] Figure 4 is a morphology diagram of tensile fracture of a sample after aging treatment at 600 DEG C for 70 min in Example 3;

[0025] Figure 5 is a morphology diagram of tensile fracture of a sample after aging treatment at 600 DEG C for 80 min in Example 4;

[0026] Figure 6 is a morphology diagram of tensile fracture of a sample after aging treatment at 650 DEG C for 60 min in Example 5;

[0027] Figure 7 is a morphology diagram of tensile fracture of a sample after aging treatment at 700 DEG C for 60 min in Example 6;

[0028] Figure 8 is a morphology diagram of tensile fracture of a sample without treatment in Comparative Example 1;

[0029] Figure 9 is a stress-strain curve of tensile of a sample after aging treatment at 600 DEG C for 70 min in Example 3. DETAILED DESCRIPTION

[0030] Example 1:

[0031] A method for improving the superplasticity of Ti65 high-temperature titanium alloy plate comprises the following steps:

[0032] A cast Ti65 high-temperature titanium alloy was subjected to EDM processing using a slow wire to obtain a plate-shaped sample with a thickness of 4.2 mm;

[0033] The plate was placed in a muffle furnace at a temperature of 1150 °C for 60 min and then hot-rolled on a rolling mill, with a thickness reduction of 0.05 mm per pass. The final thickness of the rolled plate was 1.2 mm.

[0034] Subsequently, as shown in FIG. 2, a tensile specimen was cut from the rolled plate, with a gauge length of 42.5 mm x 12.5 mm. The tensile specimen was then subjected to solution treatment at a temperature of 1050 °C for 120 min, followed by water cooling. Next, the solution-treated tensile specimen was aged at a temperature of 550 °C for 60 min, followed by air cooling. Figure 1

[0035] The aged tensile specimen was polished on sandpaper to remove surface oxides, and a Ti-1 antioxidant was uniformly applied to the surface of the specimen to protect it from high-temperature oxidation. Finally, the tensile specimen was subjected to high-temperature tensile testing at 950 °C on a universal high-temperature tensile testing machine, with a tensile strain rate of 1 x 10 -2 s -1 .

[0036] As shown in FIG. 3, the superplastic elongation of the Ti65 high-temperature titanium alloy plate prepared in this embodiment was 341% at 950 °C.

[0037] Example 2:

[0038] A method for improving the superplasticity of a Ti65 high-temperature titanium alloy plate, comprising the following steps:

[0039] A cast Ti65 high-temperature titanium alloy was subjected to EDM processing using a slow wire to obtain a plate-shaped sample with a thickness of 4.2 mm;

[0040] The plate was placed in a muffle furnace at a temperature of 1150 °C for 60 min and then hot-rolled on a rolling mill, with a thickness reduction of 0.05 mm per pass. The final thickness of the rolled plate was 1.2 mm.

[0041] Subsequently, as shown in FIG. 2, a tensile specimen was cut from the rolled plate, with a gauge length of 42.5 mm x 12.5 mm. The tensile specimen was then subjected to solution treatment at a temperature of 1050 °C for 120 min, followed by water cooling. Next, the solution-treated tensile specimen was aged at a temperature of 550 °C for 60 min, followed by air cooling. Figure 1 The aged tensile specimen was polished on sandpaper to remove surface oxides, and a Ti-1 antioxidant was uniformly applied to the surface of the specimen to protect it from high-temperature oxidation. Finally, the tensile specimen was subjected to high-temperature tensile testing at 950 °C on a universal high-temperature tensile testing machine, with a tensile strain rate of 1 x 10​​

[0042] After aging treatment, the tensile specimens were sanded on sandpaper to remove surface oxides, and Ti-1 antioxidant was uniformly coated on the specimen surface to protect them from high-temperature oxidation. Finally, the tensile specimens were subjected to a high-temperature tensile test at 950 °C on a universal high-temperature tensile testing machine, with a tensile strain rate of 1×10⁻⁶. -2 s -1 .

[0043] like Figure 3 As shown, the Ti65 high-temperature titanium alloy sheet prepared in this embodiment has a superplastic elongation of 488% when stretched at 950 °C.

[0044] Example 3:

[0045] A method for improving the superplasticity of Ti65 high-temperature titanium alloy sheets includes the following steps:

[0046] A plate-shaped sample with a thickness of 4.2 mm was obtained by electrical discharge machining of cast Ti65 high-temperature titanium alloy using a slow wire EDM.

[0047] The sheet metal was placed in a muffle furnace at 1150 ℃ and held for 60 min before being hot rolled on a rolling mill. The thickness reduction per pass was 0.05 mm, and the final thickness of the rolled sheet metal was 1.2 mm.

[0048] Subsequently, as Figure 1 As shown, tensile specimens were cut from the rolled sheet, with gauge lengths of 42.5 mm × 12.5 mm. The tensile specimens were then solution-treated in a muffle furnace at 1050 ℃ for 120 min and then water-cooled. Next, the solution-treated tensile specimens were aged in a muffle furnace at 600 ℃ for 70 min and then air-cooled.

[0049] After aging treatment, the tensile specimens were sanded on sandpaper to remove surface oxides, and Ti-1 antioxidant was uniformly coated on the specimen surface to protect them from high-temperature oxidation. Finally, the tensile specimens were subjected to a high-temperature tensile test at 950 °C on a universal high-temperature tensile testing machine, with a tensile strain rate of 1×10⁻⁶. -2 s -1 .

[0050] like Figure 4 As shown, the Ti65 high-temperature titanium alloy sheet prepared in this embodiment has a superplastic elongation of 680% when stretched at 950 °C.

[0051] Example 4:

[0052] A method for improving the superplasticity of Ti65 high-temperature titanium alloy sheets includes the following steps:

[0053] The cast Ti65 high-temperature titanium alloy was processed by electro-discharge machining to obtain a plate-shaped sample with a thickness of 4.2 mm; the plate was placed in a muffle furnace at a temperature of 1150 ℃ for 60 min and then hot-rolled on a rolling mill, with a thickness reduction of 0.05 mm per pass, and the final thickness of the rolled plate was 1.2 mm;

[0054] Subsequently, as shown in Figure 1 , a tensile specimen was cut from the rolled plate, with a gauge length of 42.5 mm x 12.5 mm, and the tensile specimen was placed in a muffle furnace at a temperature of 1050 ℃ for solid solution treatment for 120 min and then water-cooled; secondly, the solid-solution-treated tensile specimen was placed in a muffle furnace at 600 ℃ for aging treatment for 80 min and then air-cooled;

[0055] The aged tensile specimen was polished on sandpaper to remove surface oxides, and Ti-1 antioxidant was uniformly coated on the surface of the specimen to protect the tensile specimen from high-temperature oxidation; finally, the tensile specimen was subjected to high-temperature tensile testing at 950 ℃ on a universal high-temperature tensile testing machine, with a tensile strain rate of 1 x 10 -2 s -1 .

[0056] As shown in Figure 5 , the superplastic elongation of the Ti65 high-temperature titanium alloy plate prepared in this embodiment was 600% at 950 ℃.

[0057] Example 5:

[0058] A method for improving the superplasticity of a Ti65 high-temperature titanium alloy plate, comprising the following steps:

[0059] The cast Ti65 high-temperature titanium alloy was processed by electro-discharge machining to obtain a plate-shaped sample with a thickness of 4.2 mm;

[0060] The plate was placed in a muffle furnace at a temperature of 1150 ℃ for 60 min and then hot-rolled on a rolling mill, with a thickness reduction of 0.05 mm per pass, and the final thickness of the rolled plate was 1.2 mm;

[0061] Subsequently, as shown in Figure 1 , a tensile specimen was cut from the rolled plate, with a gauge length of 42.5 mm x 12.5 mm, and the tensile specimen was placed in a muffle furnace at a temperature of 1050 ℃ for solid solution treatment for 120 min and then water-cooled; secondly, the solid-solution-treated tensile specimen was placed in a muffle furnace at 650 ℃ for aging treatment for 60 min and then air-cooled;

[0062] After aging treatment, the tensile specimens were sanded on sandpaper to remove surface oxides, and Ti-1 antioxidant was uniformly coated on the specimen surface to protect them from high-temperature oxidation. Finally, the tensile specimens were subjected to a high-temperature tensile test at 950 °C on a universal high-temperature tensile testing machine, with a tensile strain rate of 1×10⁻⁶. -2 s -1 .

[0063] like Figure 6 As shown, the Ti65 high-temperature titanium alloy sheet prepared in this embodiment has a superplastic elongation of 585% when stretched at 950 °C.

[0064] Example 6:

[0065] A method for improving the superplasticity of Ti65 high-temperature titanium alloy sheets includes the following steps:

[0066] A plate-shaped sample with a thickness of 4.2 mm was obtained by electrical discharge machining of cast Ti65 high-temperature titanium alloy using a slow wire EDM.

[0067] The sheet metal was placed in a muffle furnace at 1150 ℃ and held for 60 min before being hot rolled on a rolling mill. The thickness reduction per pass was 0.05 mm, and the final thickness of the rolled sheet metal was 1.2 mm.

[0068] Subsequently, as Figure 1 As shown, tensile specimens were cut from the rolled sheet, with gauge lengths of 42.5 mm × 12.5 mm. The tensile specimens were then solution-treated in a muffle furnace at 1050 ℃ for 120 min and then water-cooled. Next, the solution-treated tensile specimens were aged in a muffle furnace at 700 ℃ for 60 min and then air-cooled.

[0069] After aging treatment, the tensile specimens were sanded on sandpaper to remove surface oxides, and Ti-1 antioxidant was uniformly coated on the specimen surface to protect them from high-temperature oxidation. Finally, the tensile specimens were subjected to a high-temperature tensile test at 950 °C on a universal high-temperature tensile testing machine, with a tensile strain rate of 1×10⁻⁶. -2 s -1 .

[0070] like Figure 7 As shown, the Ti65 high-temperature titanium alloy sheet prepared in this embodiment has a superplastic elongation of 594% when stretched at 950 °C.

[0071] Comparative Example 1:

[0072] A method for improving the superplasticity of Ti65 high-temperature titanium alloy sheets includes the following steps:

[0073] A 1.2 mm-thick plate-shaped sample was obtained by electro-discharge machining of as-cast Ti65 high-temperature titanium alloy using a slow wire;

[0074] Subsequently, as shown in Figure 1 , a tensile sample was cut out of the plate-shaped sample, the tensile sample gauge length section was 42.5 mm x 12.5 mm, and Ti-1 antioxidant was uniformly coated on the sample surface to protect the tensile sample from high-temperature oxidation;

[0075] Finally, the tensile sample was subjected to high-temperature tensile test at 950 ℃ on a universal high-temperature tensile machine, and the tensile strain rate was 1 x 10 -2 s -1 . As shown in Figure 8 , the comparative example was a Ti65 high-temperature titanium alloy plate without treatment, and the superplastic elongation of the plate when stretched at 950 ℃ was 245%.

[0076] Table 1

[0077]

[0078] As shown in Table 1, compared with the untreated comparative example 1, the high-temperature tensile elongation of the Ti65 high-temperature titanium alloy after hot rolling and annealing treatment was greatly improved, showing excellent superplasticity. As shown in Figure 9 , after 600 ℃ aging treatment for 70 min, the sample obtained a superplastic elongation of up to 680%, which was 435% higher than that of comparative example 1, and the process was simple and efficient, which made the Ti65 high-temperature titanium alloy suitable for hot working and forming of complex geometric parts in aircraft, and widened the field of view of the research on superplastic materials, and had good practicability.

[0079] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change made according to the technical essence of the present application to the above embodiment falls within the protection scope of the present application.

Claims

1. A method for improving superplasticity of Ti65 high temperature titanium alloy sheet material, characterized in that, The method comprises the following steps: Step S1: cutting to obtain Ti65 high-temperature titanium alloy plate; Step S2: heat treating the Ti65 high-temperature titanium alloy plate in a muffle furnace, and then hot rolling on a rolling mill; Step S3: solid solution treating the Ti65 high-temperature titanium alloy plate in a muffle furnace at a temperature of 1050 DEG C for 120 min, and then water cooling; Step S4: aging treating the Ti65 high-temperature titanium alloy plate in a muffle furnace at 600 DEG C for 70 min to 80 min, and then air cooling; Step S5: polishing the Ti65 high-temperature titanium alloy plate on sandpaper to eliminate surface oxides, and uniformly coating Ti-1 antioxidant on the surface of the Ti65 high-temperature titanium alloy plate to protect it from high-temperature oxidation, wherein the superplastic elongation of the treated Ti65 high-temperature titanium alloy plate at 950 DEG C is 600% to 700%.

2. The method for improving superplasticity of Ti65 high-temperature titanium alloy plate according to claim 1, characterized in that, In the step S1, the as-cast Ti65 high-temperature titanium alloy with a purity of 99.9% is prepared by using a vacuum induction levitation melting method.

3. The method for improving superplasticity of Ti65 high-temperature titanium alloy plate according to claim 2, characterized in that, In the step S1, the Ti65 high-temperature titanium alloy is subjected to slow wire electro-discharge machining to obtain the Ti65 high-temperature titanium alloy plate with a thickness of 4.2 mm.

4. The method for improving superplasticity of Ti65 high-temperature titanium alloy plate according to claim 1, characterized in that, In the step S2, the Ti65 high-temperature titanium alloy plate is kept in a muffle furnace at a temperature of 1150 DEG C for 60 min.

5. The method for improving superplasticity of Ti65 high-temperature titanium alloy sheet according to claim 4, characterized in that, In the step S2, the thickness is reduced by 0.05 mm in each pass, and the rolling is performed to a final thickness of 1.2 mm.

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