Ti575G titanium alloy bar as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of non-ferrous metal material processing, and particularly discloses a Ti575G titanium alloy bar and a preparation method and application thereof.The preparation method comprises the technological route of cogging forging, intermediate forging and forming forging, firstly, a large deformation technology above a phase transformation point is adopted, the thermal diffusivity of atoms under the high-temperature condition is fully utilized, and the thermal diffusivity of the atoms under the high-temperature condition is utilized; according to the method, the component and structure uniformity of a blank is greatly improved, then a repeated upsetting and drawing deformation mode is applied in a two-phase region, and meanwhile, the deformation uniformity of all positions of a bar is effectively improved by strictly controlling the temperature, the heat preservation time, upsetting and drawing deformation parameters and the like of each stage. The Ti575G bar prepared by the preparation method disclosed by the invention is uniform in component and structure, has matched strong plasticity and impact toughness characteristics, can completely meet strict requirements of wings, fuselage frames, undercarriages and weapon barrels of airplanes on the alloy bar, and is very suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous metal material processing, and specifically relates to a Ti575G titanium alloy bar and a preparation method and application thereof. The preparation method is mainly used to prepare a Ti575G titanium alloy bar with a diameter of 60 mm to 100 mm, a length of not less than 1500 mm, and both high plasticity and impact toughness. Background Art

[0002] In the modern industrial field, especially in the aerospace, high-end equipment manufacturing and other industries, the demand for high-performance materials is growing. Titanium alloys have been widely used in many fields such as aviation, aerospace, automobiles, chemicals, weapons and biomedicine due to their excellent properties, such as low density, high specific strength, corrosion resistance, good thermal strength, non-magnetic and good biocompatibility.

[0003] Among them, Ti575 titanium alloy was developed by Timetal Corporation of the United States. Its nominal composition is Ti-5.3Al-7.7V-0.5Si, which is a high-strength α+β alloy. This alloy is a new type of titanium alloy developed on the basis of TC4 titanium alloy. It has more excellent fatigue performance. Its density is equivalent to that of TC4 titanium alloy, but it is significantly better than TC4 in terms of strength and plasticity matching. However, the impact toughness of Ti575 titanium alloy is average in actual use, and it is difficult to meet those fields with high requirements for matching strength and plasticity and impact toughness, such as aircraft wings, fuselage frames, landing gears, and weapon barrels. To this end, researchers added a small amount of Mo and Zr elements to the Ti575 titanium alloy to form Ti575G titanium alloy to improve impact toughness, so that it can meet the high requirements for matching strength and plasticity and impact toughness.

[0004] Taking the weapon barrel as an example, its raw material is usually a bar. In order to make it meet the matching characteristics of good strength, plasticity and impact toughness, it is necessary to improve the composition and organizational uniformity of the bar. Ti575G alloy, as a new type of high-strength titanium alloy, has a large deformation resistance, a narrow hot working window, and is very sensitive to hot working parameters. Improper selection of hot working parameters will lead to uneven local deformation of the alloy and temperature rise, and it is impossible to achieve a reasonable match between the strength, plasticity and impact toughness of the alloy.

[0005] In view of this, the inventors propose a Ti575G titanium alloy bar and a preparation method and application thereof to overcome the defects of the prior art. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a Ti575G titanium alloy bar and its preparation method and application. The Ti575G titanium alloy bar obtained by the preparation method has uniform composition and structure, can meet the high requirements for matching strong plasticity and impact toughness, and the preparation method has a short cycle, a high degree of process stabilization, and a high yield, and is suitable for industrial production.

[0007] The purpose of the present invention is to be solved by the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a Ti575G titanium alloy bar, comprising the following steps:

[0009] Step 1: Forging

[0010] After heating the ingot to 100°C to 250°C above the phase transformation point and keeping the temperature for a set time, 2 to 3 rounds of blank forging are performed to ensure that the large as-cast grains are fully broken to obtain an intermediate blank, the forging method of which is upsetting and drawing, and air cooling after forging;

[0011] Step 2: Intermediate Forging

[0012] The intermediate billet material obtained in step 1 is heated to 10°C to 100°C below the phase transition point, and after heat preservation treatment, 2 to 4 intermediate forgings are performed to further refine and homogenize the billet structure to obtain an intermediate forging billet, wherein the forging method is upsetting and drawing, and air cooling is performed after forging;

[0013] Step 3: Forming and Forging

[0014] The intermediate forging material obtained in step 2 is heated to 30°C to 120°C below the phase transformation point, and is subjected to forming forging after heat preservation treatment. The forming forging method is fine forging, and air cooling is performed after forging to finally obtain the target Ti575G titanium alloy bar.

[0015] Furthermore, in step one, the holding time of a single fire during blank forging is calculated based on the maximum size of the material cross section of the previous time (mm)*(0.6-0.8)min, the upsetting adopts slow hammer upsetting, and the upsetting rate of a single fire is 10mm / s-25mm / s; the drawing feed amount is 100mm-250mm, and the drawing rate is 30mm / s-70mm / s; the single fire upsetting and drawing ratio is controlled at 1.2-2.0, the single-pass upsetting deformation is 30%-50%, and the cumulative deformation of blank forging is 55%-65%.

[0016] Note: “*” represents a multiplication sign throughout the text.

[0017] Furthermore, in step 2, the holding time of a single fire during intermediate forging is calculated based on the maximum size of the material cross section of the previous time (mm)*(0.5-0.8)min, the upsetting adopts slow hammer upsetting, and the upsetting rate of a single fire is 10mm / s-25mm / s; the drawing feed amount is 100mm-200mm, and the drawing rate is 20mm / s-50mm / s; the total forging ratio of single fire upsetting is controlled at 1.2-2.2, the deformation of a single pass upsetting is 25%-50%, and the cumulative deformation of intermediate forging is 65%-75%.

[0018] Furthermore, in step three, the holding time during forming forging is calculated based on the maximum size (mm)*(0.5-0.8)min of the cross section of the intermediate forging blank material obtained in step two, the deformation amount of a single pass is 10%-25%, the feed amount is 10mm-30mm, and the forging rate is 10mm / s-40mm / s.

[0019] Furthermore, the preparation method is used for Ti575G titanium alloy bars with a specification of Φ60mm to Φ100mm and a length greater than or equal to 1500mm.

[0020] In a second aspect, the present invention provides a Ti575G titanium alloy bar obtained by the above-mentioned preparation method, wherein the tensile strength Rm of the Ti575G titanium alloy bar is greater than 1150MPa, and the elongation after fracture A is greater than 20%, the cross-sectional shrinkage Z is greater than 45%, and the impact toughness aku is greater than 40J / cm 2 .

[0021] In a third aspect, the present invention provides an application of the Ti575G titanium alloy rod in aircraft wings, fuselage frames, landing gears and weapon barrels.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The Ti575G titanium alloy bar preparation method provided by the present invention first adopts a large deformation process above the phase transition point, and fully utilizes the thermal diffusion capacity of atoms under high temperature conditions to greatly improve the composition and organizational uniformity of the ingot and the bar blank. At the same time, the two-phase region uses repeated upsetting and drawing deformation methods to effectively improve the deformation uniformity of each position of the blank. And by strictly controlling key factors such as heating temperature, deformation amount and deformation method, the precise control of the organization and performance of the Ti575G alloy bar is finally achieved. The overall uniformity of the Ti575G bar prepared by this processing method is excellent, which can fully meet the strict requirements of the aircraft's wings, fuselage frames, landing gear and weapon barrels for the alloy bar, and is very suitable for industrial large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 It is a flow chart of the method for preparing Ti575G titanium alloy bar of the present invention;

[0027] Figure 2 This is a physical picture of the Ti575G titanium alloy bar (specification: Ф100mm) prepared in Example 1 of the present invention;

[0028] Figure 3 It is a low-magnification microstructure diagram of the Ti575G titanium alloy rod prepared in Example 1 of the present invention, (a) head end face, (b) tail end face;

[0029] Figure 4 The heat treatment microstructure diagram of the Ti575G titanium alloy bar prepared in Example 1 of the present invention, (a) microstructure at 1 / 2R, (b) microstructure at the core;

[0030] Figure 5 It is a low-magnification microstructure diagram of the Ti575G titanium alloy rod prepared in Example 2 of the present invention, (a) head end face, (b) tail end face;

[0031] Figure 6 1 is a heat treatment microstructure diagram of the Ti575G titanium alloy rod prepared in Example 2 of the present invention, (a) microstructure at 1 / 2R, (b) core microstructure. DETAILED DESCRIPTION

[0032] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices consistent with some aspects of the present invention as detailed in the appended claims.

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0034] See also Figure 1The present invention provides a method for preparing a Ti575G titanium alloy rod, wherein the raw material is a Ti575G titanium alloy ingot produced by three smelting processes in a vacuum consumable arc furnace, wherein the chemical composition by mass percentage of the ingot is: Al: 4.3% to 5.3%, V: 6.8% to 8.0%, Si: 0.3% to 0.7%, Mo: 0.3% to 0.5%, Zr: 0.2% to 0.5%, and the rest is titanium and unavoidable impurity elements, and the preparation method comprises the following steps;

[0035] Step 1: Forging

[0036] Select qualified ingots, then heat the billet to 100℃~250℃ above the phase transformation point (the phase transformation point of Ti575G titanium alloy is 910℃) for a set time, and then perform 2~3 rounds of open forging to ensure that the large cast grains are fully broken to obtain the intermediate billet. The forging method is upsetting and drawing, and air cooling after forging.

[0037] The blank forging method is upsetting forging, the purpose of which is to break the coarse columnar crystals through deformation and obtain a uniform and controllable recrystallization structure. The specific parameters of blank forging are as follows:

[0038] The holding time of a single fire during billet forging is calculated based on the maximum size of the material cross section in the previous fire (mm)*(0.6~0.8)min. The billet forging is explained below using two fires as an example. The holding time of the first fire is the diameter size of the original ingot*(0.6~0.8)min; the holding time of the second fire is the maximum size of the material cross section after the first fire is completed*(0.6~0.8)min.

[0039] The upsetting adopts slow hammer upsetting, and the upsetting rate of a single fire is 10mm / s~25mm / s; the feed amount of drawing is 100mm~250mm, and the drawing rate is 30mm / s~70mm / s; the upsetting and drawing ratio of a single fire is controlled at 1.2~2.0, the deformation of a single pass upsetting and drawing is 30%~50%, and the cumulative deformation of open forging is 55%~65%.

[0040] Step 2: Intermediate Forging

[0041] The intermediate billet material obtained in step 1 is heated to 10°C to 100°C below the phase transition point, and after heat preservation treatment, 2 to 4 rounds of intermediate forging are performed to further refine and homogenize the billet structure to obtain an intermediate forging billet, which is forged by upsetting and drawing, and air-cooled after forging.

[0042] The parameters of intermediate forging are as follows: The holding time of a single fire during intermediate forging is calculated based on the maximum size of the material cross section of the previous fire (mm)*(0.5~0.8)min. The intermediate forging is explained as follows using 3 fires as an example. The holding time of the first fire is the maximum size of the cross section of the intermediate billet material obtained in step 1*(0.5~0.8)min; the holding time of the second fire is the maximum size of the cross section of the material after the first fire is completed*(0.5~0.8)min; the holding time of the third fire is the maximum size of the cross section of the material after the second fire is completed*(0.5~0.8)min.

[0043] The upsetting is done by slow hammer upsetting, and the upsetting rate of a single fire is 10mm / s~25mm / s; the feeding amount of the drawing is 100mm~200mm, and the drawing rate is 20mm / s~50mm / s; the upsetting-drawing ratio of a single fire is controlled at 1.2~2.2, the deformation of a single pass is 25%~50%, and the cumulative deformation of the intermediate forging is 65%~75%. If the temperature of the adjacent fires is too low, the furnace can be returned to the furnace for heating. After the forging is completed and cooled, the end face of the billet is observed for low-power microstructure. When the low-power microstructure is uniform and fine, it indicates that the billet microstructure has been fully broken and the billet can be subjected to subsequent forming forging.

[0044] Step 3: Forming and Forging

[0045] The intermediate forging material obtained in step 2 is heated to 30°C to 120°C below the phase transformation point, and is subjected to forming forging after heat preservation treatment. The forming forging method is fine forging, and air cooling is performed after forging to finally obtain the target Ti575G titanium alloy bar.

[0046] The precision forging uses small deformation and multiple passes to ensure uniform deformation of the metal in all directions during the forging process, and finally obtains the target Ti575G titanium alloy bar with uniform composition and organization. The parameters of the forming forging are as follows:

[0047] The holding time during forming forging is calculated based on the maximum size of the cross section of the intermediate forging billet material obtained in step 2 (mm)*(0.5~0.8)min;

[0048] The deformation amount of a single pass is 10% to 25%, the feed amount is 10mm to 30mm, and the forging rate is 10mm / s to 40mm / s.

[0049] Example 1 (Ø100mm×2800mm bar)

[0050] 1) Forging (2 times)

[0051] Select qualified Φ440mm Ti575G titanium alloy ingots, heat them to 1160℃ and keep them warm for 330min, and perform two rounds of open forging. The open forging method is upsetting and drawing, as follows:

[0052] During the first fire forging, slow hammer upsetting is used for upsetting, the upsetting rate is 10mm / s, the feed amount during drawing is 200mm, the drawing rate is 60mm / s, the upsetting-drawing ratio is controlled at 1.8, the deformation per pass is 30%, and the specification of the billet after forging is □350mm (□ in the text represents square material).

[0053] Subsequently, the billet after the first forging was polished and cleaned, and then returned to the furnace for heating to 1010℃ and kept warm for 240min before the second forging. The second upsetting also adopted slow hammer upsetting, the upsetting rate was 12mm / s, the feed amount during drawing was 150mm, the drawing rate was 50mm / , the upsetting-drawing ratio was controlled at 2.0, the single-pass deformation was 30%, the cumulative deformation was 55%, the billet size after forging was □300mm, and it was air-cooled after forging.

[0054] 2) Intermediate forging (2 times)

[0055] The billet after the blanking forging in step 1) is heated to 900°C and kept warm for 200 minutes, and then the first upsetting and drawing forging is carried out. The upsetting is carried out by slow hammer upsetting, the upsetting rate is 15mm / s, the drawing feed is 180mm, the drawing rate is 30mm / s, the upsetting and drawing ratio is controlled at 1.5, the single-pass deformation is 25%, and the size after forging is □180mm.

[0056] After the first upsetting and drawing forging, the billet is polished and cleaned, then returned to the furnace and heated to 820°C, kept warm for 120 minutes, and then upsetting and drawing forging for the second time is carried out. The upsetting is also done by slow hammer upsetting, the upsetting rate is 20mm / s, the drawing feed is 150mm, the drawing rate is 25mm / s, the upsetting and drawing ratio is controlled at 1.6, the single-pass deformation is 30%, the cumulative deformation is 65%, the size after forging is Φ160mm, and air cooling is performed after forging is completed.

[0057] 3) Forming forging

[0058] After grinding and cleaning the intermediate billet obtained in step 2, it is heated to 810°C and kept warm for 100 minutes for fine forging. The deformation of the fine forging single pass is 15%, the feed amount is 20 mm, the forging rate is 25 mm / s, and the billet is Ф105 mm after forging, and air-cooled after forging.

[0059] The bar blank formed by the above forging is subsequently machined into a 100mm Φ finished bar. Figure 2 shown.

[0060] in, Figure 3 This is a macroscopic microstructure diagram of the Ti575G titanium alloy rod prepared by the preparation method of the present invention in Example 1. It can be seen that the macroscopic microstructures at the head and tail of the rod have no obvious metallurgical defects, are uniform in structure, and are fuzzy crystals. Figure 4The microstructure of the heat-treated bar is shown in Table 1. The bar microstructure is equiaxed or short rod-shaped, and the microstructures at different positions are uniform. To further verify the mechanical properties of the Ti575G titanium alloy bar prepared in this example, the bar was tested, and the room temperature tensile properties are shown in Table 1.

[0061] Table 1 Room temperature tensile properties of Ti575G titanium alloy bars with a diameter of 100 mm × 2800 mm

[0062]

[0063] Example 2 (Ø60mm×3500mm bar)

[0064] 1) Forging (2 times)

[0065] Select qualified Φ440mm Ti575G titanium alloy ingots, heat them to 1150℃ and keep them warm for 290min, and perform two rounds of open forging. The open forging method is upsetting and drawing, as follows:

[0066] During the first fire forging, slow hammer upsetting is used for upsetting, the upsetting rate is 15mm / s, the feed amount during drawing is 250mm, the drawing rate is 30mm / s, the upsetting-drawing ratio is controlled at 1.6, the deformation per pass is 35%, and the specification of the billet after forging is □350mm.

[0067] Subsequently, the billet after the first forging was polished and cleaned, and then returned to the furnace for heating to 1010℃ and kept warm for 240min before the second forging. The second upsetting also adopted slow hammer upsetting, the upsetting rate was 15mm / s, the feed amount during drawing was 200mm, the drawing rate was 50mm / , the upsetting-drawing ratio was controlled at 1.8, the single-pass deformation was 40%, the cumulative deformation was 60%, the billet size after forging was □300mm, and air cooling was performed after forging.

[0068] 2) Intermediate forging (3 times)

[0069] The billet after the blanking forging in step 1) is heated to 900°C and kept warm for 200 minutes, and then the first upsetting and drawing forging is carried out. The upsetting is carried out by slow hammer upsetting, the upsetting rate is 10mm / s, the drawing feed is 150mm, the drawing rate is 35mm / s, the upsetting and drawing ratio is controlled at 1.6, the single-pass deformation is 30%, and the size after forging is □180mm.

[0070] After the first upsetting and drawing forging, the blank is polished and cleaned, then returned to the furnace and heated to 850℃, kept warm for 120min, and then the second upsetting and drawing forging is carried out. The upsetting is also done by slow hammer upsetting, the upsetting rate is 15mm / s, the drawing feed is 120mm, the drawing rate is 30mm / s, the upsetting and drawing ratio is controlled at 1.8, the single-pass deformation is 30%, and the size after forging is □150mm.

[0071] After the second upsetting and drawing forging, the billet was polished and cleaned, then returned to the furnace and heated to 820℃, kept warm for 110 minutes, and then upsetting and drawing forging was carried out for the third time. The upsetting was also done by slow hammer upsetting, the upsetting rate was 20mm / s, the drawing feed was 150mm, the drawing rate was 25mm / s, the upsetting and drawing ratio was controlled at 1.2, the single-pass deformation was 25%, the cumulative deformation was 70%, the size after forging was Φ120mm, and air cooling was performed after forging was completed.

[0072] 3) Forming forging

[0073] After the intermediate forging is completed, the billet is ground to remove surface cracks and then fine forging is carried out at 820°C for 90 minutes. The deformation of a single pass of fine forging is 10%, the feed amount is 30 mm, the forging rate is 10 mm / s, the size after forging is Ф63 mm bar billet, and air cooling is performed after forging.

[0074] The bar blank formed by the above forging is subsequently machined into a 60mm Φ finished bar.

[0075] in, Figure 5 This is a macroscopic microstructure diagram of the Ti575G titanium alloy rod prepared by the preparation method of the present invention in Example 2. It can be seen that the macroscopic microstructures at the head and tail of the rod have no obvious metallurgical defects, are uniform in structure, and are fuzzy crystals. Figure 6 The microstructure of the heat-treated bar is shown in Table 2. The bar microstructure is equiaxed or short rod-shaped, and the microstructures at different positions are uniform. To further verify the mechanical properties of the Ti575G titanium alloy bar prepared in this example, the bar was tested, and the room temperature tensile properties are shown in Table 2 below.

[0076] Table 2 Room temperature tensile properties of Ф60mm×3500mm Ti575G titanium alloy bars

[0077]

[0078] Example 3 (Ø80mm×3100mm rod)

[0079] 1) Forging (3 times)

[0080] Select qualified Φ440mm Ti575G titanium alloy ingots, heat them to 1150℃ and keep them warm for 290min, and perform three rounds of open forging. The open forging methods are upsetting and drawing, as follows:

[0081] During the first fire forging, slow hammer upsetting is used for upsetting, the upsetting rate is 15mm / s, the feed amount during drawing is 200mm, the drawing rate is 55mm / s, the upsetting-drawing ratio is controlled at 1.6, the deformation per pass is 40%, and the specification of the billet after forging is □350mm.

[0082] Subsequently, the billet after the first forging was polished and cleaned, and then returned to the furnace for heating to 1010℃ and kept warm for 240 minutes before the second forging. The second upsetting also adopted slow hammer upsetting, the upsetting rate was 22mm / s, the feed amount during drawing was 150mm, the drawing rate was 60mm / s, the upsetting-drawing ratio was controlled at 2.0, the single-pass deformation was 40%, and the billet size after forging was □300mm.

[0083] Subsequently, the billet after the second forging was polished and cleaned, and then returned to the furnace for heating to 1000℃ and kept warm for 240min before the third forging. The third upsetting also adopted slow hammer upsetting, the upsetting rate was 18mm / s, the feed amount during drawing was 160mm, the drawing rate was 45mm / , the upsetting-drawing ratio was controlled at 1.2, the single-pass deformation was 50%, the cumulative deformation was 65%, the billet size after forging was □300mm, and it was air-cooled after forging.

[0084] 3) Intermediate forging (4 times)

[0085] The billet after the blanking forging in step 1) is heated to 900°C and kept warm for 200 minutes, and then the first upsetting and drawing forging is carried out. The upsetting is carried out by slow hammer upsetting, the upsetting rate is 15mm / s, the drawing feed amount is 150mm, the drawing rate is 35mm / s, the upsetting and drawing ratio is controlled at 1.6, the single-pass deformation is 32%, and the size after forging is □250mm.

[0086] After the first upsetting and drawing forging, the blank is polished and cleaned, then returned to the furnace and heated to 850℃, kept warm for 170 minutes, and then the second upsetting and drawing forging is carried out. The upsetting is also done by slow hammer upsetting, the upsetting rate is 20mm / s, the drawing feed is 160mm, the drawing rate is 30mm / s, the upsetting and drawing ratio is controlled at 1.8, the single-pass deformation is 35%, and the size after forging is □250mm.

[0087] After the second upsetting and drawing forging, the blank is ground and cleaned, then returned to the furnace and heated to 820°C, kept warm for 150 minutes, and then the third upsetting and drawing forging is carried out. The upsetting is also done by slow hammer upsetting, the upsetting rate is 25mm / s, the drawing feed is 100mm, the drawing rate is 50mm / s, the upsetting and drawing ratio is controlled at 1.2, and the deformation of a single pass is 40%.

[0088] After the third upsetting and drawing forging, the billet was polished and cleaned, then returned to the furnace and heated to 810℃, kept warm for 130min, and then the fourth upsetting and drawing forging was carried out. The upsetting was also done by slow hammer upsetting, the upsetting rate was 15mm / s, the drawing feed was 200mm, the drawing rate was 20mm / s, the upsetting and drawing ratio was controlled at 2.2, the single-pass deformation was 50%, the cumulative deformation was 75%, the size after forging was Φ120mm, and air cooling was performed after forging was completed.

[0089] 3) Forming forging

[0090] After the intermediate forging is completed, the billet is ground and the surface cracks are removed, and then fine forging is carried out at 790℃ for 85 minutes. The deformation of the fine forging is 25%, the feed amount is 10mm, the forging rate is 40mm / s, the size after forging is Ф88mm bar billet, and air cooling is performed after forging.

[0091] The bar blank formed by the above forging is subsequently machined into a Ø80mm finished bar.

[0092] In order to verify the mechanical properties of the Ti575G titanium alloy rod prepared in this example, the rod was tested, and the room temperature tensile performance results are shown in Table 2 below.

[0093] Table 3 Room temperature tensile properties of Ф80mm×3100mm Ti575G titanium alloy bars

[0094]

[0095] In summary, it can be seen from the data in Tables 1 to 3 that the Ti575G titanium alloy bar prepared by the preparation method of the present invention has good matching characteristics of strength and plasticity and impact toughness, with a tensile strength Rm greater than 1150MPa, a post-fracture elongation A greater than 20%, a cross-sectional shrinkage Z greater than 45%, and an impact toughness aku greater than 40J / cm 2 That is, both the strength and plasticity meet the standard requirements with sufficient surplus, so it can fully meet the aircraft wings, fuselage frames, landing gears, weapon barrels and other areas that have high requirements for matching strength, plasticity and impact toughness.

[0096] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent 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.

[0097] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing a Ti575G titanium alloy bar, characterized in that: The raw material of the Ti575G titanium alloy rod is a Ti575G titanium alloy ingot produced by three smelting in a vacuum consumable arc furnace. The chemical composition of the ingot is as follows: Al: 4.3% to 5.3%, V: 6.8% to 8.0%, Si: 0.3% to 0.7%, Mo: 0.3% to 0.5%, Zr: 0.2% to 0.5%, and the rest is titanium and unavoidable impurity elements. The preparation method comprises the following steps: Step 1: Forging After heating the ingot to 100°C to 250°C above the phase transformation point and keeping the temperature for a set time, 2 to 3 rounds of blank forging are performed to ensure that the large as-cast grains are fully broken to obtain an intermediate blank, the forging method of which is upsetting and drawing, and air cooling after forging; Step 2: Intermediate Forging The intermediate billet material obtained in step 1 is heated to 10°C to 100°C below the phase transition point, and after heat preservation treatment, 2 to 4 intermediate forgings are performed to further refine and homogenize the billet structure to obtain an intermediate forging billet, wherein the forging method is upsetting and drawing, and air cooling is performed after forging; Step 3: Forming and Forging The intermediate forging material obtained in step 2 is heated to 30°C to 120°C below the phase transformation point, and is subjected to forming forging after heat preservation treatment. The forming forging method is fine forging, and air cooling is performed after forging to finally obtain the target Ti575G titanium alloy bar.

2. The method for preparing the Ti575G titanium alloy bar according to claim 1, characterized in that: In step 1, the holding time of a single fire during billet forging is calculated based on the maximum size of the previous material cross section (mm)*(0.6-0.8)min.

3. The method for preparing the Ti575G titanium alloy bar according to claim 1, characterized in that: In step 1, the parameters of billet forging are as follows: The upsetting adopts slow hammer upsetting, and the upsetting rate of a single fire is 10mm / s~25mm / s; the feed amount of drawing is 100mm~250mm, and the drawing rate is 30mm / s~70mm / s; the upsetting and drawing ratio of a single fire is controlled at 1.2~2.0, the deformation of a single pass upsetting and drawing is 30%~50%, and the cumulative deformation of open forging is 55%~65%.

4. The method for preparing the Ti575G titanium alloy bar according to claim 1, characterized in that: In step 2, the holding time of a single fire during intermediate forging is calculated based on the maximum size of the previous material cross section (mm)*(0.5-0.8)min.

5. The method for preparing the Ti575G titanium alloy bar according to claim 1, characterized in that: In step 2, the parameters of the intermediate forging are as follows: The upsetting adopts slow hammer upsetting, and the upsetting rate of a single fire is 10mm / s~25mm / s; the feed amount of drawing is 100mm~200mm, and the drawing rate is 20mm / s~50mm / s; the total forging ratio of single fire upsetting is controlled at 1.2~2.2, the deformation of a single pass upsetting is 25%~50%, and the cumulative deformation of intermediate forging is 65%~75%.

6. The method for preparing the Ti575G titanium alloy bar according to claim 1, characterized in that: In step three, the holding time during forming forging is calculated based on the maximum size (mm)*(0.5-0.8)min of the cross section of the intermediate forging blank material obtained in step two.

7. The method for preparing the Ti575G titanium alloy bar according to claim 1, characterized in that: In step 3, the parameters of the forming forging are as follows: The deformation amount of a single pass is 10% to 25%, the feed amount is 10mm to 30mm, and the forging rate is 10mm / s to 40mm / s.

8. The method for preparing the Ti575G titanium alloy bar according to claim 1, characterized in that: The preparation method is used for Ti575G titanium alloy bars with specifications of 60 mm to 100 mm and a length greater than or equal to 1500 mm.

9. A Ti575G titanium alloy bar prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The tensile strength Rm of the Ti575G titanium alloy bar is greater than 1150MPa, while the elongation after fracture A is greater than 20%, the cross-sectional shrinkage Z is greater than 45%, and the impact toughness aku is greater than 40J / cm 2 .

10. An application of the Ti575G titanium alloy rod according to claim 9 in aircraft wings, fuselage frames, landing gears and weapon barrels.

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