Preparation method and application of low-cost ultrahigh-strength high-toughness heterostructure TB18 titanium alloy forged plate

Abstract

The invention belongs to the technical field of non-ferrous metal processing, and particularly relates to a preparation method and application of a low-cost ultrahigh-strength high-toughness heterostructure TB18 titanium alloy forged plate. When the preparation method is adopted, firstly, a TB18 titanium alloy cast ingot to be treated is subjected to single-heating-number cogging forging at the temperature above the phase transformation point temperature, then an obtained blank is subjected to multi-heating-number forging and modified forging, and the TB18 titanium alloy forged plate is obtained. And finally, the obtained forged plate is sequentially subjected to solid solution heat treatment and two times of aging heat treatment, and the heterostructure TB18 titanium alloy forged plate is obtained after cooling. The preparation method is short in period and low in cost, the strength, plasticity and toughness of the obtained titanium alloy forged plate with the heterostructure are all improved, the tensile strength Rm of the TB18 titanium alloy forged plate with the heterostructure is larger than or equal to 1310 MPa, the impact toughness aku of the TB18 titanium alloy forged plate with the heterostructure is larger than or equal to 25 J / cm < 2 >, the fracture toughness KIC of the TB18 titanium alloy forged plate with the heterostructure is larger than or equal to 75 MPa.m < 1 / 2 >, and the use requirements of the service environment of aviation aircrafts are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-ferrous metal processing, and particularly relates to a preparation method and application of a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forging plate. Background Art

[0002] TB18 titanium alloy is a new type of metastable β titanium alloy with a Mo equivalent of 13.8 - 25. The phase transformation point temperature of this alloy is about 800 °C, and it can be used to manufacture key load-bearing components with high strength requirements in aviation equipment. With the development of new-generation aircraft towards high speed, large size, complex structure, and high fuel efficiency, the requirements for structural materials are getting higher and higher. Not only the strength level of titanium alloy needs to be improved, but also higher requirements are put forward for the plasticity and toughness of titanium alloy.

[0003] At present, in order to obtain the high strength and high toughness properties of TB18 titanium alloy forgings, a single-phase region solution + aging process is often used. However, this process is prone to "β brittleness", resulting in poor plasticity of the material. In addition, there are some problems in the existing technology, such as complex preparation process, long cycle, high pressure requirements for forging equipment, and the small size of the prepared titanium alloy forgings, with poor plasticity and toughness of the forgings.

[0004] In view of this, the present invention provides a preparation method and application of a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forging plate to solve the above technical problems. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned disadvantages of the existing technology and propose a preparation method and application of a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forging plate.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] On the one hand, the present invention provides a preparation method of a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forging plate, including the following steps:

[0008] Step 1: Subject the TB18 titanium alloy ingot to be processed to single-pass cogging forging above the phase transformation point temperature, and obtain the first intermediate billet after cooling;

[0009] Step 2: Forge the first intermediate billet 1 - 3 times below the phase transformation point temperature, and obtain the second intermediate billet after cooling;

[0010] Step 3: Redo the forging of the second intermediate billet 1 - 5 times above the phase transformation point temperature, and the redo forging is carried out by upsetting and drawing, and obtain the forging blank after cooling;

[0011] Step 4: Forge the forged blank stock at a temperature above the phase transformation point for 1 - 2 heats to obtain a forged plate;

[0012] Step 5: Perform solution heat treatment and two times of aging heat treatment on the forged plate in sequence, and after cooling, obtain the required heterogeneous structure titanium alloy forged plate.

[0013] Specifically, Step 1 is as follows: First, heat the TB18 titanium alloy ingot to a temperature 300°C - 500°C above the phase transformation point, with a heating rate of 8°C / min - 20°C / min, hold for 10h - 30h, then perform cogging forging in the way of three upsetting and three drawing, control the forging ratio to be 1.5 - 2.5, cool in water after forging to obtain a first intermediate blank with a square cross-section, and finally perform octagonal chamfering on the first intermediate blank.

[0014] Specifically, in Step 2, each heat forging is as follows: First, heat the first intermediate blank to a temperature 20°C - 60°C below the phase transformation point, with a heating rate of 8°C / min - 20°C / min, hold for 8h - 12h, then perform square upsetting and drawing, control the forging ratio to be 1.2 - 2.2, cool in water after forging to obtain a second intermediate blank with a square cross-section.

[0015] Specifically, in Step 3, each heat remanufacturing is as follows: First, heat the second intermediate blank to a temperature 30°C - 200°C above the phase transformation point, with a heating rate of 8°C / min - 20°C / min, hold for 8h - 12h, then select reverse upsetting and drawing, control the forging ratio to be 1.5 - 2.5, cool in air after forging to obtain a forged blank stock with a square cross-section.

[0016] Specifically, in Step 4, each heat forging is as follows: First, heat the forged blank stock to a temperature 30°C - 150°C above the phase transformation point, with a heating rate of 8°C / min - 20°C / min, hold for 4h - 8h, then perform forging, control the forging ratio to be 1.2 - 2.5, cool in air after forging to obtain a forged plate with a rectangular cross-section.

[0017] Specifically, in Step 5, first heat the forged plate from room temperature to a temperature 30°C - 150°C above the phase transformation point for solution heat treatment, with a heating rate of 8°C / min - 20°C / min, hold for 2h - 5h and then cool in air to obtain a solution-state forged plate, and then perform two times of aging heat treatment on the solution-state forged plate.

[0018] Specifically, in Step 5, the two times of aging heat treatment include primary aging heat treatment and secondary aging heat treatment;

[0019] The primary aging heat treatment is specifically as follows: Heat the forged plate obtained after solution heat treatment from room temperature to 550°C - 650°C, with a heating rate of 8°C / min - 20°C / min, hold for 0.5h - 4h and then quench in water to obtain a primary aging-state forged plate;

[0020] The secondary aging heat treatment is specifically as follows: heating the primary aging state forged plate from room temperature to 450°C - 550°C at a heating rate of 8°C / min - 20°C / min, holding for 0.5 h - 4 h, and then air cooling to obtain the corresponding heterogeneous structure titanium alloy forged plate.

[0021] On the other hand, the heterogeneous structure titanium alloy forged plate prepared by the preparation method of a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forged plate, after testing, its tensile strength ≥ 1310 MPa, impact toughness ≥ 25 J / cm 2 , fracture toughness ≥ 75 MPa·m 1 / 2 .

[0022] On yet another aspect, the present invention provides an application of the preparation method of a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forged plate, which is applied to the preparation of load-bearing components in the aerospace field.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] In this preparation method, after forging the billet in the α+β phase region, heat treatment is carried out above the phase transformation point temperature. By using deformation + recrystallization heating, recrystallization of the billet is realized to obtain an intermediate billet with initially uniform structure. Then, multi-pass forging is carried out above the phase transformation point temperature. After β annealing and solution treatment, the combination of dynamic and static recrystallization is used to finally ensure the consistency of the structure and properties at different positions of the forged plate. At the same time, after β annealing and solution treatment, the primary α phase dissolves back into the β matrix, reducing the stability of the β matrix, which is beneficial to subsequent aging precipitation and realizes aging strengthening;

[0025] Furthermore, in this preparation method, the primary aging state forged plate of the present preparation method first precipitates intermediate transition phases (β` and β`` phases) through spinodal decomposition of the composition, and then the secondary α phase precipitates in the way of β→β`→α during the secondary aging heat treatment process. The secondary α phase is finer and more dispersed, improving the strength of the alloy. At the same time, due to the lower temperature of the secondary aging heat treatment, it is difficult to realize β``→α, and the β`` phase, as a soft phase that can coordinate deformation, still exists in the structure after the secondary aging heat treatment, thereby improving the plasticity and fracture toughness of the alloy;

[0026] Furthermore, in this preparation method, two-stage aging heat treatment from high temperature to low temperature is carried out to form a microstructure mainly composed of β single-phase heterogeneous structure and fine needle-like α s phase. Compared with the existing homogeneous structure titanium alloy process, this preparation method has a short cycle and low cost, and the strength, plasticity and toughness of the obtained titanium alloy forged plate are all improved;

[0027] Furthermore, through testing, for the heterogeneous structure TB18 titanium alloy forging plates prepared by the preparation method of the present invention, their tensile strength is all ≥1310 MPa, yield strength is all ≥1200 MPa, impact toughness is all ≥25 J / cm 2 , fracture toughness is all ≥75 MPa·m 1 / 2 , meeting the usage requirements of the service environment of aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings here are incorporated into the specification and constitute a part of this specification, and are used together with the specification to explain the principles of the present invention.

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 is a flowchart of the preparation method of the present invention;

[0031] Figure 2 is a macrostructure micrograph of the heterogeneous structure titanium alloy forging plate A in Example 1 of the present invention;

[0032] Figure 3 is a microstructure micrograph at high magnification of the heterogeneous structure titanium alloy forging plate A in Example 1 of the present invention;

[0033] Figure 4 is a scanning electron microstructure micrograph of the heterogeneous structure titanium alloy forging plate A in Example 1 of the present invention;

[0034] Figure 5 is a macrostructure micrograph of the heterogeneous structure titanium alloy forging plate B in Example 2 of the present invention;

[0035] Figure 6 is a microstructure micrograph at high magnification of the heterogeneous structure titanium alloy forging plate B in Example 2 of the present invention;

[0036] Figure 7 is a scanning electron microstructure micrograph of the heterogeneous structure titanium alloy forging plate B in Example 2 of the present invention;

[0037] Figure 8 is a macrostructure micrograph of the heterogeneous structure titanium alloy forging plate C in Example 3 of the present invention;

[0038] Figure 9 is a microstructure micrograph at high magnification of the heterogeneous structure titanium alloy forging plate C in Example 3 of the present invention;

[0039] Figure 10This is the scanning electron micrograph of the heterogeneous structure titanium alloy forging plate C in Embodiment 3 of the present invention. Detailed implementation manners

[0040] Here, the exemplary embodiments will be described in detail. The implementation manners described in the following exemplary embodiments do not represent all implementation manners 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.

[0041] The present invention provides a method for preparing a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forging plate, including the following steps:

[0042] Step 1: Perform single-pass cogging forging on the to-be-treated TB18 titanium alloy ingot above the phase transformation point temperature, and obtain the first intermediate blank after cooling.

[0043] Step 2: Forge the first intermediate blank 1 to 3 times below the phase transformation point temperature, and obtain the second intermediate blank after cooling.

[0044] Step 3: Redraw the second intermediate blank 1 to 5 times above the phase transformation point temperature. The redrawing is carried out by upsetting and drawing, and obtain the forging blank after cooling.

[0045] Step 4: Forge the forging blank 1 to 2 times above the phase transformation point temperature to obtain the forging plate.

[0046] Step 5: Perform solution heat treatment and two aging heat treatments on the forging plate in sequence, and obtain the required heterogeneous structure titanium alloy forging plate after cooling.

[0047] Further, Step 1 is specifically: first heat the TB18 titanium alloy ingot to 300°C to 500°C above the phase transformation point temperature, with a heating rate of 8°C / min to 20°C / min, hold for 10h to 30h, then perform cogging forging in the way of three-upsetting and three-drawing, control the forging ratio to be 1.5 to 2.5, perform water cooling after forging, obtain the first intermediate blank with a square cross-section, and finally perform octagonal chamfering on the first intermediate blank.

[0048] Further, in Step 2, each forging is specifically: first heat the first intermediate blank to 20°C to 60°C below the phase transformation point temperature, with a heating rate of 8°C / min to 20°C / min, hold for 8h to 12h, then perform square upsetting and drawing, control the forging ratio to be 1.2 to 2.2, perform water cooling after forging, and obtain the second intermediate blank with a square cross-section.

[0049] Further, in step three, the forging and re-forging for each heat are specifically as follows: First, heat the second intermediate billet to 30°C to 200°C above the phase transformation point temperature at a heating rate of 8°C / min to 20°C / min, hold for 8h to 12h, then select cross upsetting and drawing out, control the forging ratio to be 1.5 to 2.5, and air cool after forging to obtain a forged blank with a square cross-section.

[0050] Further, in step four, the forging for each heat is specifically as follows: First, heat the forged blank to 30°C to 150°C above the phase transformation point temperature at a heating rate of 8°C / min to 20°C / min, hold for 4h to 8h, then perform forging, control the forging ratio to be 1.2 to 2.5, and air cool after forging to obtain a forged plate with a rectangular cross-section.

[0051] Further, in step five, first heat the forged plate from room temperature to 30°C to 150°C above the phase transformation point temperature for solution heat treatment at a heating rate of 8°C / min to 20°C / min, hold for 2h to 5h and then air cool to obtain a solution-state forged plate, and then perform two-step aging heat treatment on the solution-state forged plate.

[0052] Further, in step five, the two-step aging heat treatment includes primary aging heat treatment and secondary aging heat treatment;

[0053] The primary aging heat treatment is specifically as follows: Heat the forged plate obtained after solution heat treatment from room temperature to 550°C to 650°C at a heating rate of 8°C / min to 20°C / min, hold for 0.5h to 4h and then water quench to obtain a primary aging-state forged plate;

[0054] The secondary aging heat treatment is specifically as follows: Heat the primary aging-state forged plate from room temperature to 450°C to 550°C at a heating rate of 8°C / min to 20°C / min, hold for 0.5h to 4h and then air cool to obtain the required heterogeneous structure titanium alloy forged plate.

[0055] In order to further verify the efficacy of the preparation method of the present invention, the inventor carried out the following specific examples:

[0056] Example 1

[0057] See Figure 1 As shown, this example provides a preparation method for a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forged plate, including the following steps:

[0058] Step 1: First, heat the ingot to 1170°C at a heating rate of 20°C / min, hold for 20h, then perform cogging forging in the way of three upsetting and three drawing out, with a forging ratio of 2.2, water cool after forging to obtain a first intermediate billet with a square cross-section, and then perform octagonal chamfering on the first intermediate billet;

[0059] Step 2: Forge the first intermediate blank in 2 heating passes. Each heating pass is as follows: First, heat the first intermediate blank to 60°C below the phase transformation point temperature at a heating rate of 20°C / min, hold for 8 h, then perform square upsetting and drawing, with a forging ratio of 1.7, and water-cool after forging to obtain a second intermediate blank with a square cross-section;

[0060] Step 3: Redo the forging of the second intermediate blank in 5 heating passes. Each heating pass for re-forging is as follows: First, heat the second intermediate blank to 100°C above the phase transformation point temperature at a heating rate of 20°C / min, hold for 9 h, then perform upsetting and drawing, control the forging ratio to 2.2, and air-cool after forging to obtain a forging blank with a square cross-section; It should be noted that for adjacent heating passes, reverse upsetting and drawing are required;

[0061] Step 4: First, heat the forging blank to 40°C above the phase transformation point temperature at a heating rate of 20°C / min, hold for 7 h, then perform 1 heating pass of forming forging, with a forging ratio of 2.2, and air-cool after forging to obtain a forged plate with specifications of 800 mm (length) × 450 mm (width) × 250 mm (thickness);

[0062] Step 5: First, heat the forged plate from room temperature to 30°C above the phase transformation point temperature at a heating rate of 20°C / min, hold for 3 h, perform solution heat treatment, and then air-cool to obtain a solution-state forged plate;

[0063] Heat the solution-state forged plate from room temperature to 600°C at a heating rate of 20°C / min, water-quench after holding for 3 h to obtain a first-stage aged forged plate; Then heat the first-stage aged forged plate from room temperature to 520°C at a heating rate of 20°C / min, air-cool after holding for 3 h to obtain a heterogeneous structure titanium alloy forged plate A.

[0064] See Figures 2 to 4 shown in Figure 2 is the macrostructure micrograph of the heterogeneous structure titanium alloy forged plate A. It can be concluded that there are no delamination, cracks, pores, segregation, metal and non-metal inclusions, and other visible metallurgical defects on the surface of the heterogeneous structure titanium alloy forged plate A, and the structure is uniform. Figure 3 and Figure 4 are respectively the high-magnification microstructure micrograph and scanning electron microstructure micrograph of the heat-treated heterogeneous structure titanium alloy forged plate A. The heat-treated microstructure mainly consists of equiaxed β grains, lamellar secondary α s phase, and β single-phase heterogeneous structure; Through observation, the size of the equiaxed β grains is 100 μm - 300 μm, the thickness size of the secondary α s phase is 50 nm - 300 nm, and the size of the β single-phase heterogeneous structure is 40 μm - 300 μm.

[0065] Example 2

[0066] See Figure 1As shown in the figure, this embodiment provides a method for preparing a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forging plate, including the following steps:

[0067] Step 1: First, heat the ingot to 1100 °C at a heating rate of 15 °C / min, hold for 20 h, then perform cogging forging in the way of three upsetting and three drawing, with a forging ratio of 2.4, and water cool after forging to obtain a first intermediate blank with a square cross-section, and then perform octagonal chamfering on the first intermediate blank;

[0068] Step 2: Perform forging on the first intermediate blank for 3 heating passes. Each heating pass of forging is as follows: First, heat the first intermediate blank to 40 °C below the phase transformation point temperature at a heating rate of 15 °C / min, hold for 10 h, then perform square upsetting and drawing, with a forging ratio of 1.9, and water cool after forging to obtain a second intermediate blank with a square cross-section;

[0069] Step 3: Perform remolding forging on the second intermediate blank for 4 heating passes. Each heating pass of remolding forging is as follows: First, heat the second intermediate blank to 120 °C above the phase transformation point temperature at a heating rate of 15 °C / min, hold for 9 h, then perform upsetting and drawing, with a forging ratio of 2.0, and air cool after forging to obtain a forging blank with a square cross-section;

[0070] Step 4: First, heat the forging blank to 50 °C above the phase transformation point temperature at a heating rate of 15 °C / min, hold for 6 h, then perform forming forging for 2 heating passes, with a forging ratio of 1.8, and air cool after forging to obtain a forging plate with the specifications of 900 mm (length) × 750 mm (width) × 240 mm (thickness);

[0071] Step 5: First, heat the forging plate from room temperature to 70 °C above the phase transformation point temperature at a heating rate of 15 °C / min, hold for 3 h, perform solution heat treatment, and then air cool to obtain a solution-state forging plate;

[0072] Then, heat the solution-state forging plate from room temperature to 600 °C at a heating rate of 15 °C / min, quench after holding for 0.5 h to obtain a first-stage aged forging plate; then place the first-stage aged forging plate in an aging furnace, heat it to 520 °C at a heating rate of 15 °C / min, air cool after holding for 1.5 h to obtain a heterogeneous structure titanium alloy forging plate B.

[0073] See Figures 5 to 7 as shown Figure 5 is the macrostructure micrograph of the heterogeneous structure titanium alloy forging plate B. It can be concluded that the surface of the heterogeneous structure titanium alloy forging plate B has no delamination, cracks, pores, segregation, metal and non-metal inclusions and other metallurgical defects visible to the naked eye, and the macrostructure is uniform. Figure 6 、 Figure 7 are respectively the high-magnification microstructure micrograph and scanning electron microstructure micrograph of the heat-treated state of the heterogeneous structure titanium alloy forging plate B. The microstructure in the heat-treated state mainly consists of equiaxed β grains and lamellar secondary αs It is composed of an α phase and a β single-phase heterogeneous structure; through observation, it is obtained that the equiaxed β grain size is 100μm to 250μm, and the thickness of the secondary α phase is 50nm to 200nm, and the size of the β single-phase heterogeneous structure is 40μm to 250μm. s

[0074] Example 3

[0075] See Figure 1 As shown, this example provides a preparation method for a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forging plate, including the following steps:

[0076] Step 1: First, heat the ingot to 1250°C at a heating rate of 10°C / min, hold for 15h, then use the method of three upsetting and three drawing to perform cogging forging, with a forging ratio of 1.7, and water cool after forging to obtain a first intermediate blank with a square cross-section, and then perform an octagonal treatment on the first intermediate blank;

[0077] Step 2: Perform forging on the first intermediate blank in 2 heating passes. Each heating pass of forging is as follows: First, heat the first intermediate blank to 65°C below the phase transformation point temperature at a heating rate of 10°C / min, hold for 12h, then perform square upsetting and drawing on it, with a forging ratio of 1.7, and water cool after forging to obtain a second intermediate blank with a square cross-section;

[0078] Step 3: Perform secondary forging on the second intermediate blank in 2 heating passes. Each heating pass of secondary forging is as follows: First, heat the second intermediate blank to 40°C above the phase transformation point temperature at a heating rate of 10°C / min, hold for 8h, then perform upsetting and drawing, with a forging ratio of 1.9, and air cool after forging to obtain a forging blank with a square cross-section; It should be noted that adjacent heating passes need to change the direction of upsetting and drawing:

[0079] Step 4: First, heat the forging blank to 50°C above the phase transformation point temperature at a heating rate of 10°C / min, hold for 7h, then perform 1 heating pass of forming forging, with a forging ratio of 2.2, and air cool after forging to obtain a forging plate with specifications of: 800mm (length) × 650mm (width) × 150mm (thickness);

[0080] Step 5: First, heat the forging plate from room temperature to 100°C above the phase transformation point temperature at a heating rate of 10°C / min, hold for 2h, perform solution heat treatment, and then air cool to obtain a solution-state forging plate;

[0081] Then heat the solution-state forging plate from room temperature to 550°C at a heating rate of 10°C / min, hold for 3h and then water quench to obtain a first-stage aged forging plate; Then heat the first-stage aged forging plate from room temperature to 450°C at a heating rate of 10°C / min, hold for 4h and then air cool to obtain a heterogeneous structure titanium alloy forging plate C.

[0082] SeeFigures 8 to 10 As shown Figure 8 is the macrostructure diagram of the heterogeneous structure titanium alloy forging plate C. It can be concluded that there are no delamination, cracks, pores, segregation, metal and non-metal inclusions and other visible metallurgical defects in the macrostructure of the heterogeneous structure titanium alloy forging plate C, and the macrostructure is uniform. Figure 9 、 Figure 10 are respectively the heat-treated microstructure diagram and the scanning electron microstructure diagram of the heterogeneous structure titanium alloy forging plate C. The heat-treated microstructure is mainly composed of equiaxed β grains, lamellar secondary α s phase, and β single-phase heterogeneous structure; Through observation, the size of the equiaxed β grains is 100μm - 280μm, and the thickness of the secondary α s phase is 50μm - 300nm, and the size of the β single-phase heterogeneous structure is 40μm - 280μm.

[0083] To further verify the effectiveness of the technical solution provided by the present invention, cut specimens were respectively taken from the titanium alloy forging plate A, the titanium alloy forging plate B, and the titanium alloy forging plate C, and the following mechanical property tests were carried out in the LT direction, ST direction, and L direction:

[0084] Tensile strength, yield strength, elongation, impact toughness, fracture toughness, and the test results are shown in Table 1.

[0085] Table 1

[0086]

[0087] In summary, it can be seen from Table 1 that for the heterogeneous structure titanium alloy forging plates prepared by the preparation method of the present invention, their tensile strength is ≥1310MPa, yield strength is ≥1200MPa, impact toughness is ≥25J / cm 2 , and fracture toughness is ≥75MPa·m 1 / 2 , which can fully meet the service environment requirements of aircraft.

[0088] The above are only specific embodiments of the present invention, enabling 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 content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A preparation method of a low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forging plate, characterized in that, It includes the following steps: Step 1: Subject the TB18 titanium alloy ingot to be processed to cogging forging in a single heat treatment above the phase transition point temperature, and obtain the first intermediate blank after cooling; Step 2: Forge the first intermediate blank 1 to 3 times below the phase transition point temperature, and obtain the second intermediate blank after cooling; Step 3: Perform 1 to 5 times of sizing forging on the second intermediate blank above the phase transition point temperature. The sizing forging is carried out by upsetting and drawing, and obtain the forged blank after cooling; Step 4: Forge the forged blank 1 to 2 times above the phase transition point temperature to obtain a forged plate; Step 5: Successively perform solution heat treatment and two times of aging heat treatment on the forged plate, and obtain the required heterogeneous structure titanium alloy forged plate after cooling.

2. The preparation method according to claim 1, characterized in that, Specifically, Step 1 is as follows: First, heat the TB18 titanium alloy ingot to 300°C to 500°C above the phase transition point temperature, with a heating rate of 8°C / min to 20°C / min, hold for 10h to 30h, then carry out cogging forging by the method of three upsetting and three drawing, control the forging ratio to 1.5 to 2.5, water-cool after forging, obtain the first intermediate blank with a square cross-section, and finally perform octagonal chamfering on the first intermediate blank.

3. The preparation method according to claim 1, wherein In Step 2, each forging is specifically as follows: First, heat the first intermediate blank to 20°C to 60°C below the phase transition point temperature, with a heating rate of 8°C / min to 20°C / min, hold for 8h to 12h, then carry out square upsetting and drawing, control the forging ratio to 1.2 to 2.2, water-cool after forging, and obtain the second intermediate blank with a square cross-section.

4. The preparation method according to claim 1, characterized in that, In Step 3, each sizing forging is specifically as follows: First, heat the second intermediate blank to 30°C to 200°C above the phase transition point temperature, with a heating rate of 8°C / min to 20°C / min, hold for 8h to 12h, then carry out upsetting and drawing, control the forging ratio to 1.5 to 2.5, air-cool after forging, and obtain the forged blank with a square cross-section.

5. The preparation method according to claim 1, characterized in that, In Step 4, each forging is specifically as follows: First, heat the forged blank to 30°C to 150°C above the phase transition point temperature, with a heating rate of 8°C / min to 20°C / min, hold for 4h to 8h, then carry out forging, control the forging ratio to 1.2 to 2.5, air-cool after forging, and obtain the forged plate with a rectangular cross-section.

6. The preparation method according to claim 1, characterized in that, In Step 5, first heat the forged plate from room temperature to 30°C to 150°C above the phase transition point temperature for solution heat treatment, with a heating rate of 8°C / min to 20°C / min, air-cool after holding for 2h to 5h to obtain the solution-state forged plate, and then perform two times of aging heat treatment on the solution-state forged plate.

7. The preparation method according to claim 1, wherein In Step 5, the two times of aging heat treatment include primary aging heat treatment and secondary aging heat treatment; Specifically, the primary aging heat treatment is as follows: Heat the forged plate obtained after solution heat treatment from room temperature to 550°C to 650°C, with a heating rate of 8°C / min to 20°C / min, water-quench after holding for 0.5h to 4h to obtain the primary aging-state forged plate; Specifically, the secondary aging heat treatment is as follows: Heat the primary aging-state forged plate from room temperature to 450°C to 550°C, with a heating rate of 8°C / min to 20°C / min, air-cool after holding for 0.5h to 4h to obtain the corresponding heterogeneous structure titanium alloy forged plate.

8. The heterogeneous structure titanium alloy forging plate prepared by the preparation method of the low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forging plate according to any one of claims 1 to 7, characterized in that, After testing, its tensile strength ≥ 1310 MPa, impact toughness ≥ 25 J / cm 2 , fracture toughness ≥ 75 MPa·m 1 / 2 .

9. Use of the preparation method of the low-cost ultra-high strength and high toughness heterogeneous structure TB18 titanium alloy forging plate according to any one of claims 1 to 7, characterized in that, It is applied to the preparation of load-bearing components in the aerospace field.

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