Heat treatment method for improving high-temperature mechanical property of TA15 titanium alloy

Abstract

The invention relates to the technical field of titanium alloy heat treatment, in particular to a heat treatment method for improving the high-temperature mechanical property of TA15 titanium alloy, and the heat treatment method comprises the following steps: 1) cogging, rolling and cooling a TA15 titanium alloy plate blank to obtain a TA15 titanium alloy hot-rolled plate; (2) the TA15 titanium alloy hot-rolled plate is subjected to near-beta heat treatment and quenching cooling, and a TA15 titanium alloy plate subjected to near-beta heat treatment is obtained; (3) the TA15 titanium alloy plate obtained in the step (2) is subjected to two-phase region heat treatment and cooled; according to the method, the TA15 titanium alloy plate blank is subjected to hot rolling treatment, then the near-beta heat treatment and the two-phase region heat treatment are sequentially carried out, the microstructure of the TA15 titanium alloy plate is regulated and controlled through the synergistic effect of the two heat treatment methods, the mechanical property of the TA15 titanium alloy plate at the high temperature is remarkably improved, and the reliability of the TA15 titanium alloy at the high temperature can be effectively improved; and the defect that the high-temperature performance of a traditional annealed structure is relatively low is overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy heat treatment, and in particular to a heat treatment method for improving the high-temperature mechanical properties of TA15 titanium alloy. Background Art

[0002] Titanium alloys, with their excellent lightweight properties, exceptional specific strength, and outstanding creep resistance, have become an indispensable key material in the modern aerospace field. In my country's aerospace field, the most widely used titanium alloy grade is TA15. The nominal composition of TA15 titanium alloy is Ti-6.5Al-2Zr-1Mo-1V, which is a near-α-type titanium alloy. While maintaining the lightweight advantages of titanium alloys, this alloy exhibits unique thermal stability characteristics and can achieve continuous and stable operation for up to thousands of hours in a high-temperature environment of 500°C. Therefore, TA15 titanium alloy can be used to prepare key titanium alloy structural parts that serve for a long time in a high-temperature environment of 500°C. In order to ensure safety and reliability during service, extremely stringent requirements are placed on the mechanical properties of TA15 titanium alloy at high temperatures, which poses a major technical challenge to the microstructure control and heat treatment process optimization of TA15 titanium alloy.

[0003] In the aerospace industry, TA15 titanium alloy sheet is primarily used at relatively high ambient temperatures, placing stringent demands on its mechanical properties at high temperatures. Currently, conventional TA15 titanium alloy sheet production methods typically involve rolling followed by recrystallization annealing, using multiple rolling passes to achieve grain crushing and combined with recrystallization annealing for microstructure control. This often results in an equiaxed or bimodal microstructure. Titanium alloys with this microstructure exhibit relatively low mechanical properties at high temperatures, which can affect the service life of TA15 titanium alloy sheet and place limitations on improving the material's high-temperature performance. Research has shown that a microstructure combining equiaxed and basketweave microstructures (equiaxed α phase + lamellar α phase + β transformation) significantly enhances the high-temperature mechanical properties and thermal stability of TA15 titanium alloy while maintaining strength and toughness. Therefore, new heat treatment processes are needed to manipulate the microstructure of TA15 titanium alloy sheet to improve its mechanical properties and reliability at high temperatures. Summary of the Invention

[0004] In response to the above-mentioned deficiencies in the prior art, the present invention provides a heat treatment method for improving the high-temperature mechanical properties of TA15 titanium alloy. The method comprises hot rolling the TA15 titanium alloy slab, and then sequentially performing a near-β heat treatment and a two-phase zone heat treatment. The two heat treatment methods synergistically achieve the regulation of the microstructure of the TA15 titanium alloy plate, significantly improving its mechanical properties at high temperatures, effectively extending the reliability of the TA15 titanium alloy at high temperatures, and improving the deficiency of relatively low high-temperature performance of the traditional annealed structure.

[0005] In order to achieve the above objectives, in a first aspect, the present invention provides a heat treatment method for improving the high-temperature mechanical properties of TA15 titanium alloy, the heat treatment method comprising: 1) rolling and cooling the TA15 titanium alloy slab to obtain a TA15 titanium alloy hot-rolled plate; 2) performing a near-β heat treatment on the TA15 titanium alloy hot-rolled plate, and quenching and cooling the plate to obtain a near-β heat-treated TA15 titanium alloy plate; 3) The TA15 titanium alloy plate obtained in step 2) is subjected to two-phase zone heat treatment and cooled.

[0006] Preferably, in step 1), the cooling conditions include: a temperature of 15-30°C. Preferably, in step 1), the thickness of the TA15 titanium alloy hot-rolled plate is 40-80 mm.

[0007] Preferably, in step 2), the conditions of the near-β heat treatment include: a temperature of (T β -40)~(T β -20)℃, where T β is the temperature of the β phase transition point; the time is 90~120min.

[0008] Preferably, in step 2), the quenching cooling conditions include: using water as a cooling medium and cooling to 15-30°C.

[0009] Preferably, in step 3), the conditions for the two-phase region heat treatment include: a temperature of (T β -100)~(T β -60)℃, where T β is the temperature of the β phase transition point; the time is 100~150min.

[0010] Preferably, in step 3), the cooling conditions include: air cooling to 15-30°C.

[0011] In a second aspect, the present invention provides a TA15 titanium alloy, wherein the interior of the TA15 titanium alloy is composed of an equiaxed α phase, a lamellar α phase, and a β transformation structure; The TA15 titanium alloy is prepared by the heat treatment method described in the first aspect.

[0012] In the above technical scheme, the heat treatment method of the present invention for improving the high-temperature mechanical properties of TA15 titanium alloy is achieved by synergistically treating the TA15 titanium alloy plate with two heat treatment methods to regulate the microstructure of the TA15 titanium alloy plate. The interior of the TA15 titanium alloy plate is composed of equiaxed α phase + lamellar α phase + β transformation structure, which not only makes the high-magnification structure of the TA15 titanium alloy plate have both equiaxed and basketweave characteristics of the microstructure, but also the obtained TA15 titanium alloy plate structure is uniform and fine, without obvious coarse structure; the fine equiaxed α phase plays a role in regulating plastic deformation and ensures the plastic deformation ability; the staggered lamellar α phase will change the crack propagation path, and will also effectively hinder the slip of dislocations and improve the strength of the system; and the β transformation structure improves the mechanical properties of the system at high temperature through the solid solution strengthening effect.

[0013] Furthermore, the high-temperature mechanical properties of TA15 titanium alloy sheets produced using the method of this invention are significantly improved compared to equiaxed structures, which increases their reliability in high-temperature environments. Furthermore, without compromising their room-temperature mechanical properties, the high-temperature mechanical properties and stability at high temperatures are effectively enhanced.

[0014] Furthermore, the heat treatment method of the present invention is simple to operate, easy to control, has relatively low technical difficulty, is suitable for industrial production, and has good application prospects.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 This is a metallographic diagram of the TA15 titanium alloy plate in Example 1 of the present invention; Figure 2 This is a metallographic diagram of the TA15 titanium alloy plate in Example 2 of the present invention; Figure 3 This is a metallographic diagram of the TA15 titanium alloy plate in Example 3 of the present invention; Figure 4 This is a metallographic diagram of the TA15 titanium alloy plate in Comparative Example 1 of the present invention; Figure 5 This is a metallographic diagram of the TA15 titanium alloy plate in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0017] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0018] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0019] In a first aspect, the present invention provides a heat treatment method for improving the high-temperature mechanical properties of TA15 titanium alloy, the heat treatment method comprising: 1) rolling and cooling the TA15 titanium alloy slab to obtain a TA15 titanium alloy hot-rolled plate; 2) performing a near-β heat treatment on the TA15 titanium alloy hot-rolled plate, and quenching and cooling the plate to obtain a near-β heat-treated TA15 titanium alloy plate; 3) The TA15 titanium alloy plate obtained in step 2) is subjected to two-phase zone heat treatment and cooled.

[0020] The heat treatment method for improving the high-temperature mechanical properties of TA15 titanium alloy of the present invention uses two heat treatment methods to synergistically treat the TA15 titanium alloy plate to regulate the microstructure of the TA15 titanium alloy plate. The interior of the TA15 titanium alloy plate is composed of equiaxed α phase + lamellar α phase + β transformation structure, which not only makes the high-magnification structure of the TA15 titanium alloy plate have the microstructure of equiaxed and basketweave characteristics at the same time, but also the obtained TA15 titanium alloy plate structure is uniform and fine, without obvious coarse structure; the fine equiaxed α phase plays a role in regulating plastic deformation and ensures the plastic deformation ability; the staggered lamellar α phase will change the crack propagation path, and will also effectively hinder the slip of dislocations and improve the strength of the system; and the β transformation structure improves the mechanical properties of the system at high temperature through the solid solution strengthening effect.

[0021] In a preferred embodiment of the present invention, in order to ensure that the TA15 titanium alloy slab is fully deformed, in step 1), the slab rolling needs to be repeated multiple times until a TA15 titanium alloy hot-rolled plate with a thickness of 40-80 mm is obtained.

[0022] In a preferred embodiment of the present invention, in step 1), the cooling condition includes: a temperature of 15-30°C.

[0023] In a preferred embodiment of the present invention, in step 1), the thickness of the TA15 titanium alloy hot-rolled plate is 40-80 mm.

[0024] In a preferred embodiment of the present invention, in order to ensure that the TA15 titanium alloy hot-rolled plate is heated through, in step 2), the conditions of the near-β heat treatment include: a temperature of (T β-40)~(T β -20)℃, where T β is the temperature of the β phase transition point; the time is 90~120min.

[0025] In a preferred embodiment of the present invention, the near-β heat treatment requires the temperature to reach the near-β heat treatment temperature before loading the furnace, and the timing is started after reaching the temperature.

[0026] In a preferred embodiment of the present invention, in step 2), the quenching cooling conditions include: using water as a cooling medium, cooling to 15-30°C, and needing to be performed quickly after the TA15 titanium alloy sheet is taken out of the furnace to prevent the impact of temperature drop.

[0027] In a preferred embodiment of the present invention, in order to ensure that the TA15 titanium alloy sheet is heated through, in step 3), the conditions for the two-phase region heat treatment include: a temperature of (T β -100)~(T β -60)℃, where T β is the temperature of the β phase transition point; the time is 100~150min.

[0028] In a preferred embodiment of the present invention, the two-phase zone heat treatment requires the temperature to reach the two-phase zone heat treatment temperature before loading the furnace, and the timing is started after reaching the temperature.

[0029] In a preferred embodiment of the present invention, in step 3), the cooling conditions include: air cooling to 15-30°C.

[0030] In a second aspect, the present invention provides a TA15 titanium alloy, wherein the interior of the TA15 titanium alloy is composed of an equiaxed α phase, a lamellar α phase, and a β transformation structure; The TA15 titanium alloy is prepared by the heat treatment method described in the first aspect.

[0031] The TA15 titanium alloy plate prepared by the present invention is internally composed of equiaxed α phase + lamellar α phase + β transformation structure, among which the fine equiaxed α phase plays a role in regulating plastic deformation and ensures the plastic deformation ability; the staggered lamellar α phase will change the crack propagation path, and will also effectively hinder the slip of dislocations and improve the strength of the system; and the β transformation structure improves the mechanical properties of the system at high temperature through the solid solution strengthening effect.

[0032] The present invention will be described in detail below by way of examples. In the following examples, the drugs and pharmaceuticals are all conventional commercial products.

[0033] The room temperature mentioned in the present invention is 15~30℃.

[0034] Example 1 (1) A TA15 titanium alloy slab with a size of 280 mm × 1400 mm × 1300 mm was placed on a hot rolling mill for blanking and rolling to obtain a TA15 titanium alloy hot-rolled plate with a thickness of 70 mm, which was then cooled to room temperature (15-30°C) to obtain a TA15 titanium alloy hot-rolled plate; (2) The TA15 titanium alloy hot-rolled plate was subjected to near-β heat treatment at a temperature of 970°C for 100 min, and then placed in water for quenching until cooled to room temperature; (3) The quenched TA15 titanium alloy sheet was subjected to two-phase zone heat treatment at a temperature of 920 °C for 150 min, and then air-cooled to room temperature to obtain a two-step heat-treated TA15 titanium alloy sheet, which was recorded as B1. The temperature T of the β phase transition point of the TA15 titanium alloy hot-rolled plate in this embodiment is β =990℃.

[0035] Example 2 (1) Placing a TA15 titanium alloy slab with a specification of 200 mm × 1000 mm × 1600 mm on a hot rolling mill for blanking and rolling to obtain a TA15 titanium alloy hot-rolled plate with a thickness of 65 mm, and cooling it to room temperature to obtain a TA15 titanium alloy hot-rolled plate; (2) The TA15 titanium alloy hot-rolled plate was subjected to near-β heat treatment at a temperature of 950°C for 90 min, and then placed in water for quenching until cooled to room temperature; (3) The quenched TA15 titanium alloy sheet was subjected to two-phase zone heat treatment at a temperature of 900 °C for 120 min, and then air-cooled to room temperature to obtain a two-step heat-treated TA15 titanium alloy sheet, which was recorded as B2. The temperature T of the β phase transition point of the TA15 titanium alloy hot-rolled plate in this embodiment is β =985℃.

[0036] Example 3 (1) Placing a TA15 titanium alloy slab with a specification of 230 mm × 1400 mm × 1000 mm on a hot rolling mill for blanking and rolling to obtain a TA15 titanium alloy hot-rolled plate with a thickness of 45 mm, and cooling it to room temperature to obtain a TA15 titanium alloy hot-rolled plate; (2) The TA15 titanium alloy hot-rolled plate was subjected to near-β heat treatment at a temperature of 945°C for 90 min, and then placed in water for quenching until cooled to room temperature; (3) The quenched TA15 titanium alloy sheet was subjected to two-phase zone heat treatment at a temperature of 890 °C for 100 min, and then air-cooled to room temperature to obtain a two-step heat-treated TA15 titanium alloy sheet, which was designated as B3. The temperature T of the β phase transition point of the TA15 titanium alloy hot-rolled plate in this embodiment is β =985℃.

[0037] Comparative Example 1 A TA15 titanium alloy slab with a specification of 280 mm × 1400 mm × 1300 mm was placed on a hot rolling mill for blanking and rolling to obtain a TA15 titanium alloy hot-rolled plate with a thickness of 70 mm. The TA15 titanium alloy plate was annealed at 830°C for 110 min and then air-cooled to room temperature to obtain a TA15 titanium alloy plate, which was recorded as D1.

[0038] Comparative Example 2 A TA15 titanium alloy slab with a specification of 230 mm × 1400 mm × 1000 mm was placed on a hot rolling mill for blanking and rolling to obtain a TA15 titanium alloy hot-rolled plate with a thickness of 45 mm. The TA15 titanium alloy plate was annealed at 760°C for 90 min and air-cooled to room temperature to obtain a TA15 titanium alloy plate, which was recorded as D2.

[0039] Test Example 1 The TA15 titanium alloy plates prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention were subjected to metallographic analysis. The metallographic organization diagrams of the plates are shown in FIG. Figure 1-Figure 5 shown.

[0040] Depend on Figure 1-Figure 3 It can be seen that the TA15 titanium alloy plate obtained after the two-step heat treatment in Examples 1-3 of the present invention has a uniform and fine structure, and has the characteristics of equiaxed and basketweave structures; while the TA15 titanium alloy plate obtained after only annealing treatment in Comparative Examples 1-2 has only equiaxed structure, and the structure is relatively uniform.

[0041] Test Example 2 At 500° C., high-temperature mechanical properties of the TA15 titanium alloy plates prepared in Examples 1-3 of the present invention and Comparative Examples 1-2 were tested. The high-temperature mechanical properties of the plates are shown in Table 1.

[0042] Table 1

[0043] It can be seen from the data in Table 1 that the tensile strength of the TA15 titanium alloy plates obtained in Examples 1-3 of the present invention at high temperatures is significantly improved compared to the TA15 titanium alloy plates obtained in Comparative Examples 1-2, while the yield strength is slightly improved. Compared with the conventional process, the TA15 titanium alloy plates prepared by the method of the present invention have the characteristics of both equiaxed and basketweave structures. In terms of high-temperature mechanical properties, while ensuring that the yield strength is not reduced, the tensile strength is greatly improved, thereby achieving an improvement in the high-temperature mechanical properties of the TA15 titanium alloy plates and increasing their reliability in high-temperature environments.

[0044] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0045] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0046] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A heat treatment method for improving the high temperature mechanical properties of TA15 titanium alloy, characterized in that: The heat treatment method comprises: 1) rolling and cooling the TA15 titanium alloy slab to obtain a TA15 titanium alloy hot-rolled plate; 2) performing a near-β heat treatment on the TA15 titanium alloy hot-rolled plate, and quenching and cooling the plate to obtain a near-β heat-treated TA15 titanium alloy plate; 3) The TA15 titanium alloy plate obtained in step 2) is subjected to two-phase zone heat treatment and cooled.

2. The heat treatment method according to claim 1, characterized in that In step 1), the cooling conditions include: a temperature of 15-30°C.

3. The heat treatment method according to claim 1 or 2, characterized in that In step 1), the thickness of the TA15 titanium alloy hot-rolled plate is 40-80 mm.

4. The heat treatment method according to claim 1, wherein in step 2), the conditions of the near-β heat treatment include: Temperature (T β -40)~(T β -20)℃, where T β is the temperature of the β phase transition point; the time is 90~120min.

5. The heat treatment method according to claim 1, wherein In step 2), the quenching cooling conditions include: using water as a cooling medium and cooling to 15-30°C.

6. The heat treatment method according to claim 1, characterized in that In step 3), the conditions for the two-phase region heat treatment include: a temperature of (T β -100)~(T β -60)℃, where T β is the temperature of the β phase transition point; the time is 100~150min.

7. The heat treatment method according to claim 1, characterized in that In step 3), the cooling conditions include: air cooling to 15-30°C.

8. A TA15 titanium alloy, characterized in that: The interior of the TA15 titanium alloy is composed of equiaxed α phase, lamellar α phase and β transformation structure; The TA15 titanium alloy is prepared by the heat treatment method according to any one of claims 1 to 7.

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