JP2017002373A - Titanium alloy forging material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a titanium alloy forging material excellent in strength, ductility and toughness.SOLUTION: There is provided a titanium alloy forging material consisting of a titanium alloy having Mo equivalent [Mo]represented by the following formula of 10 or more and less than 13, where content of an element X (mass%) is [X], [Mo]=[Mo]+[Ta]/5+[Nb]/3.6+[W]/2.5+[V]/1.5+1.25[Cr]+1.25[Ni]+1.7[Mn]+1.7[Co]+2.5[Fe] and having a particle diameter of 5 μm or more, area percentage of a primary α phase with an aspect ratio of 2 or more of 1% or less, area percentage of a primary α phase with a particle diameter of 0.5 μm or more of over 0% and 20% or less and an aspect ratio of a β phase between primary α phases of 2.0 or more.SELECTED DRAWING: None

Description

  The present invention relates to a titanium alloy forging, and more particularly to a near β-type titanium alloy forging.

  Aircraft parts are required to have high ductility, high toughness, etc. in addition to being lightweight and high in strength, so α + β type titanium alloys and near β type titanium alloys are often used. . α + β-type titanium alloy has excellent balance of strength, ductility, etc. because the α phase of dense hexagonal crystal (hcp structure), which is the main phase, and β phase of body-centered cubic crystal (bcc structure) coexist stably at room temperature. Moreover, it becomes a β phase single phase in a temperature range equal to or higher than the β transformation point (Tβ). The near β-type titanium alloy has an intermediate metal structure between the α + β-type titanium alloy and the high-strength β-type titanium alloy, and the α-phase and the β-phase coexist in the same manner as the α + β-type titanium alloy. These titanium alloy forgings include α + β forging that heats and forges to a temperature range below Tβ (α + β two-phase region) so as not to reach a temperature above Tβ, and a temperature range above Tβ (β single unit). There is a thing by the β forging which heats and forges to a phase region. It is known that the α + β forged material and the β forged material have completely different material structures and have different material properties.

  Among titanium alloys, Ti-10V-2Fe-3Al alloy is known as a high-strength near β-type titanium alloy. In order to further improve the properties of the Ti-10V-2Fe-3Al alloy, several improved techniques have been developed. For example, Patent Document 1 discloses a processing pretreatment method that improves the cold workability while maintaining the high strength properties of the near β-type titanium alloy. Patent Document 2 discloses a treatment method for obtaining a near β-type titanium alloy having excellent strength and toughness.

JP-A-1-96361 Japanese Patent No. 3334354

  However, aircraft parts are required to have further improved strength, ductility and toughness. Generally, when the strength is increased, the toughness and ductility tend to decrease. The processing methods disclosed in Patent Document 1 and Patent Document 2 still have room for improvement in strength, ductility and toughness.

  This invention is made | formed in view of the said problem, and makes it a subject to provide the titanium alloy forging material excellent in intensity | strength, ductility, and toughness.

  As a result of earnest research, the inventors reduced the coarse primary α phase as much as possible, further reduced the area ratio of the primary α phase, and then increased the aspect ratio of the β phase adjacent to the secondary α phase, It was found that the ductility and fracture toughness can be improved while maintaining the strength, and the present invention has been achieved.

That is, in the titanium alloy forging according to the present invention, when the content (mass%) of the element X is [X], the Mo equivalent [Mo] _eq represented by the following formula (1) is 10 or more and less than 13 A titanium alloy forging made of a titanium alloy,
[Mo] _eq = [Mo] + [Ta] / 5 + [Nb] /3.6+ [W] /2.5+ [V] /1.5+1.25 [Cr] +1.25 [Ni] +1.7 [ Mn] +1.7 [Co] +2.5 [Fe] (1)
The area ratio of the primary α phase having a particle diameter of 5 μm or more and an aspect ratio of 2 or more is 1% or less, the area ratio of the primary α phase having a particle diameter of 0.5 μm or more is more than 0% and 20% or less, The aspect ratio of the β phase between the next α phases is 2.0 or more.

  The titanium alloy forging material having such a structure has an α phase and a β phase in a specific manner, and is excellent in strength, ductility and toughness.

  In the titanium alloy forged material according to the present invention, the average interval between the secondary α phases is preferably 250 nm or less. The titanium alloy forging material having such a configuration is further excellent in strength.

  In the titanium alloy forging according to the present invention, the titanium alloy contains V: 9.0 to 11.0% by mass, Al: 2.6 to 3.4% by mass, Fe: 1.6 to 2.22. It is preferable that it contains mass% and the balance is Ti and inevitable impurities. The titanium alloy forged material having such a configuration is further excellent in strength, ductility and toughness.

  The titanium alloy forging according to the present invention is excellent in all of the properties of strength, ductility and toughness.

It is a schematic diagram which shows the method of calculating the average space | interval of a secondary alpha phase.

Hereinafter, embodiments of the present invention will be described in detail.
[Titanium alloy forging]
The titanium alloy forged material according to the present invention is a titanium alloy forged material that can be used for aircraft parts and the like, and has a structure excellent in strength, ductility, and toughness by controlling the metal structure by forging or heat treatment. It is said.

In the titanium alloy forging according to the present invention, when the content (mass%) of the element X is [X], the Mo (molybdenum) equivalent [Mo] _eq represented by the following formula (1) is 10 or more and 13 It is a titanium alloy forging material made of a titanium alloy that is less than.
[Mo] _eq = [Mo] + [Ta] / 5 + [Nb] /3.6+ [W] /2.5+ [V] /1.5+1.25 [Cr] +1.25 [Ni] +1.7 [ Mn] +1.7 [Co] +2.5 [Fe] (1)
Mo equivalent is generally used as an index indicating the stability of each phase of the titanium alloy. For details of Mo equivalent, see G. Lutjering & JC Williams, "Titanium", Second Edition, Springer-Verlag, Berlin, 2010, p30 or Furuhara, Maki, Metal, vol.66 (1996), No.4, p289, etc. Is explained.
The Mo equivalent must have a value of 10 or more, more preferably 10.5 or more, in order to ensure strength. On the other hand, in order to make hot forgeability and ductility favorable, it is necessary to control to less than 13, More preferably, it is 12.5 or less.

[Titanium alloy]
There is a Ti-10V-2Fe-3Al alloy defined in AMS4984 as a titanium alloy satisfying the above-mentioned definition of Mo equivalent. The alloy composition of Ti-10V-2Fe-3Al alloy contains V: 9.0 to 11.0 mass%, Al: 2.6 to 3.4 mass%, Fe: 1.6 to 2.22 mass% The balance is Ti and inevitable impurities. As unavoidable impurities, for example, C: 0.05 mass% or less, N: 0.05 mass% or less, O: 0.13 mass% or less, H: 0.015 mass% or less, Y: 0.005 mass % Or less. Here, the Mo equivalent is calculated as a content of 0 for an element not contained in the Ti-10V-2Fe-3Al alloy in the formula (1).

  In the case of Ti-10V-2Fe-3Al alloy, V: 9.0% by mass or more and Fe: 1.6% by mass or more are necessary for solid solution strengthening of β phase and stabilization of β phase. In order to strengthen the solid solution strengthening of the phase and stabilize the α phase, Al: 2.6% by mass or more is necessary. Moreover, since excessive addition may impair hot forgeability and ductility, it controls to V: 11.0 mass% or less, Al: 3.4 mass% or less, and Fe: 2.22 mass% or less. In addition, if the inevitable impurities increase, the material may become brittle, so the upper limit is controlled as described above.

  Other examples of the titanium alloy having an Mo equivalent of 10 or more and less than 13 include Ti-5Al-5V-5Mo-3Cr alloy.

[Metal structure]
The metal structure of the titanium alloy is generally composed of an α phase and a β phase, and the α phase is further classified into a primary α phase and a secondary α phase. The metal structure of the forged titanium alloy of the present invention has a particle size of 5 μm or more, an area ratio of primary α phase of 2 or more in aspect ratio of 1% or less, and an area ratio of primary α phase of particle diameter of 0.5 μm or more. More than 0% and 20% or less, and the aspect ratio of β phase between secondary α phases is 2.0 or more. Moreover, it is preferable that the average space | interval of a secondary alpha phase is 250 nm or less. Hereinafter, each characteristic will be sequentially described.

  The metal structure of the titanium alloy forged material of the present invention substantially consists of an α phase and a β phase. The α phase is composed of a primary α phase and a secondary α phase. The secondary α phase is an α phase precipitated in the aging process, and the primary α phase is an α phase other than the secondary α phase. The structure other than the α phase and the β phase may contain a small amount of carbides, inclusions, and the like.

  When the area ratio of the primary α phase (hereinafter sometimes referred to as “coarse α phase”) having a particle size of 5 μm or more and an aspect ratio of 2 or more is present in a titanium alloy metal structure exceeding 1%, Ductility decreases. This is presumably because when the α phase particle size is coarse and the aspect ratio is large, strain tends to concentrate on the primary α phase and ductility tends to decrease. Therefore, the metal structure of the forged titanium alloy of the present invention controls the area ratio of the coarse α phase to 1% or less. The area ratio of the coarse α phase is preferably 0.9% or less. Here, the coarse α phase is intended only for the primary α phase and not the secondary α phase. The area ratio of the coarse α phase can be measured by image analysis of an optical micrograph. As a method of controlling the area ratio of the coarse α phase to 1% or less, there is a method of performing forging under predetermined conditions, details of which will be described later.

  When the area ratio of the primary α phase of the titanium alloy having a particle size of 0.5 μm or more is 20% or less, the strength can be increased while ensuring fracture toughness. In order to ensure ductility, a certain amount of the primary α phase is necessary, but if it is contained in an area ratio exceeding 20%, fracture toughness and strength are lowered. Further, when the α phase is 0%, it is difficult to ensure ductility. Therefore, the metal structure of the titanium alloy forged material of the present invention controls the area ratio of the primary α phase having a particle size of 0.5 μm or more to more than 0% and 20% or less. The area ratio of the primary α phase having a particle size of 0.5 μm or more is preferably 3% or more, less than 15%, and more preferably less than 10%. The area ratio of the primary α phase can be measured by image analysis of an optical micrograph. As a method for controlling the area ratio of the primary α phase, there is a method in which the temperature of the solution treatment is performed under a predetermined condition, details of which will be described later. The area ratio of the primary α phase with a particle size of 0.5 μm or more is counted for the primary α phase with a particle size of 5 μm or more and an aspect ratio of 2 or more, and the primary particle size of 5 μm is independent of the aspect ratio. α phase is counted.

  The metal structure of the titanium alloy forged material of the present invention has an aspect ratio of β phase between secondary α phases of 2.0 or more. By setting the aspect ratio of the β phase between the secondary α phases to 2.0 or more, the fracture toughness of the titanium alloy forged material can be improved. This is considered to be because crack growth is suppressed by making the β phase between the secondary α phases into a shape with a large aspect ratio. The aspect ratio of the β phase between the secondary α phases is preferably 2.3 or more. The aspect ratio of the β phase between the secondary α phases can be measured by image analysis of an optical micrograph. As a method for controlling the aspect ratio of the β phase between the secondary α phases, there is a method in which a solution treatment or an aging treatment is performed under predetermined conditions, details of which will be described later.

  The metal structure of the titanium alloy forged material of the present invention preferably has an average interval between secondary α phases of 250 nm or less. By setting the average interval of the secondary α phase to 250 nm or less, the strength can be increased while ensuring the ductility and fracture toughness of the titanium alloy forged material. The average interval between secondary α phases is more preferably 220 nm or less. On the other hand, if the average interval between the secondary α phases is extremely small, the material may be embrittled, so that it is preferably 100 nm or more, and more preferably 120 nm or more. The average interval between secondary α phases can be calculated as described later with reference to SEM photographs. As a method for controlling the average interval of the secondary α phase, there is a method in which the cooling rate after the solution treatment and the aging treatment temperature are performed under predetermined conditions, details of which will be described later.

[Production method of titanium alloy forging]
The titanium alloy forging material having the above-described metal structure can be manufactured by applying the method for manufacturing a titanium alloy forging material described below. The method for producing a titanium alloy forged material of the present invention is characterized in that processing is performed under the specific processing conditions described below in each of the forging step, the solution treatment step, and the aging step.

  The titanium alloy forged material according to the present invention is manufactured into a desired product shape by forging an ingot made of a titanium alloy having the above composition into a billet under the following conditions, followed by solution treatment and aging treatment. In addition, about a manufacturing process and manufacturing conditions other than the manufacturing conditions described below, a titanium alloy forging material can be obtained by performing well-known conditions suitably.

(Forging process)
In the forging process, forging is performed by heating to the β transformation region, and the shape as a forging material is adjusted. Thereafter, the steel is heated to the α + β temperature region and forged so that the equivalent strain amount in the α + β region becomes 2 to 10 (hereinafter, the accumulated equivalent strain amount is referred to as “accumulated strain amount ε”). . By increasing the cumulative strain amount ε to 2 or more, the area ratio of the coarse α phase can be reduced to 1% or less. In order to increase the cumulative strain amount ε, heating and forging may be repeated in a plurality of times. The cumulative strain amount ε may exceed 10, but is set to 2 to 10 because the effect is saturated. The cumulative strain amount ε is preferably 3 to 9. In order to set the cumulative strain amount ε to 2, for example, when uniform deformation is assumed by uniaxial compression, the rolling reduction (working degree) may be about 86%. Similarly, in order to set the cumulative strain amount ε to 10, the reduction rate may be approximately 100%. Here, the cumulative strain amount ε was calculated as ε = ln (t0 / t), to: test piece height before compression, and t: test piece height after compression.

  On the other hand, since the area ratio of the coarse α phase increases as the heating time increases, the total cumulative heating time (holding time at 700 ° C. or higher) is controlled to 90 hours or shorter. The cumulative heating time is preferably 80 hr or less. Thus, forging under the condition that the cumulative strain amount ε is as large as possible and the cumulative heating time is as small as possible, that is, while increasing the cumulative strain amount ε while shortening the cumulative heating time, It is important to suppress the area ratio of the coarse α phase to 1% or less and ensure the elongation as a titanium alloy forged material.

  Here, the equivalent strain amount is also referred to as an equivalent plastic strain amount. The amount of equivalent strain in the α + β region at the specimen collection position can be measured by analysis using commercially available FEM analysis software (for example, analysis software “FORGE” manufactured by TRANSVALOR). Similarly, the accumulated strain amount ε can be measured by analyzing the accumulated equivalent plastic strain amount when forging is performed a plurality of times using commercially available FEM analysis software.

(Solution process)
After forging, the solution treatment is performed by heating and holding in a temperature range of (Tβ-60) ° C. to Tβ ° C. Here, Tβ is a β transformation point. Moreover, the rate of temperature rise when raising the temperature to the solution treatment temperature is controlled to a rate exceeding 0.06 ° C./sec. If the rate of temperature increase is 0.06 ° C./sec or less, or if the solution treatment temperature is less than (Tβ-60) ° C., the area ratio of the primary α phase tends to increase, and the β phase between the secondary α phases Aspect ratio tends to decrease. On the other hand, when the solution treatment temperature exceeds Tβ ° C., defects (freckle) are likely to occur. By maintaining the solution treatment temperature in the temperature range of (Tβ-60) ° C. to Tβ ° C., the area ratio of the primary α phase having a particle size of 0.5 μm or more can be appropriately controlled. The solution treatment temperature is preferably as close to Tβ as possible. The holding time of the solution treatment is preferably 1 to 5 hours. Thus, it is preferable that the solution treatment is performed at a relatively high temperature for a relatively long time by raising the temperature earlier. Furthermore, when the solution treatment temperature is T (° C.) and the treatment time is t (minutes), the heat treatment parameter T × logt is preferably 1400 or more, and more preferably 1500 or more.

  Moreover, the cooling rate after heating and holding at the solution treatment temperature is controlled to 0.5 ° C./sec to 15 ° C./sec. When the cooling rate is slow, the average interval between the secondary α phases tends to be coarse. If the cooling rate is too fast, the aspect ratio of the β phase between the secondary α phases tends to decrease. Therefore, in order to obtain a β phase between secondary α phases having an aspect ratio of 2.0 or more, the cooling rate after heating and holding is controlled within a range of 0.5 ° C./sec to 15 ° C./sec. .

(Aging process)
After cooling in the solution treatment step, aging treatment is performed by heating and holding in a temperature range of 485 ° C to 520 ° C. The aging treatment temperature is preferably 490 to 515 ° C. When the temperature is lower than 485 ° C., the β phase aspect ratio between the secondary α phases tends to decrease, and the average interval between the secondary α phases tends to decrease. When it exceeds 520 ° C., the average interval between secondary α phases tends to increase. The holding time of the aging treatment is 4 to 12 hours. Therefore, in order to obtain a β phase between secondary α phases having an aspect ratio of 2.0 or more, an aging treatment is performed by heating and holding in a temperature range of 485 ° C. to 520 ° C.

  Examples in which the effects of the present invention have been confirmed will be specifically described below in comparison with comparative examples that do not satisfy the requirements of the present invention. In addition, this invention is not limited to a following example.

[Production of test materials]
Using a billet made of a Ti-10V-2Fe-3Al alloy (Tβ: 810 ° C., Mo equivalent of 11.7) defined by AMS 4984, after forging at a temperature of 810 ° C. or higher of the β transformation point, listed in Table 1 Under each condition, heating holding and hot working assuming finish forging in the α + β region were performed. Table 1 shows the cumulative strain amount ε in finish forging in the α + β region.

  Using the forged material, solution treatment and aging treatment were performed under the conditions shown in Table 1. After heating and holding the solution, the cooling rate was changed as shown in Table 1 by adjusting the cooling method (water cooling, air cooling, air cooling) and the specimen collection position. The heating rate and cooling rate were measured by inserting a thermocouple at the same depth as the specimen collection position. On the other hand, in the aging treatment, after heating and holding at a predetermined temperature, all were cooled to room temperature by air cooling. The time for solution heat treatment and aging treatment was the time after placing in the furnace at the heating temperature shown in the table.

[Evaluation of test material]
About the obtained test material, various physical properties were measured and evaluated under the evaluation conditions described below.
(Tensile test)
The test piece was collected so that the forging direction and the load axis direction of the tensile test piece were parallel. Four test pieces were collected per condition. At this time, each test piece was sampled from a position where the distance from the forged material surface to the test piece sampling position was equivalent in order to equalize the strain amount and the cooling rate at the four test piece positions. The tensile test was performed in accordance with ASTM standard E8. The specimen size was ASTM E8 Specimen2. From the test results, those having a 0.2% proof stress exceeding 1050 MPa and an elongation exceeding 10% were regarded as acceptable.

(Fracture toughness test)
Conducted in accordance with ASTM E399. The test piece was collected in the S-L direction, and the thickness of the test piece was 19 mm. The obtained result was calculated as a fracture toughness value KIC (MPa · m ^1/2 ). When KIC was 30 or more, it was determined to be acceptable.

(Tissue observation)
(1) Average interval between secondary α phases Immediately after the tensile specimen is collected so that a cross-section parallel to the L direction of the forged material (which can be identified by the direction of β crystal grain extension when observed with an optical microscope) can be observed. A block for tissue observation was cut out from the adjacent location. Resin embedding, polishing, and corrosion (fluoric nitric acid solution) were performed to obtain a sample for SEM observation. Thereafter, observation was performed at a magnification of 400 times, and the grains determined to have an equivalent circle diameter of 0.5 μm or more were defined as the primary α phase, and the regions of less than 0.5 μm were defined as other regions such as the secondary α phase and β phase. Magnified photograph (magnification) using FE-SEM (Field Emission Scanning Electron Microscope) (Hitachi, Ltd., SU-70) in the region containing only β phase and secondary α phase (region not including primary α phase) 30,000 times) was obtained per condition. Based on the photograph, five line segments were drawn at equal intervals from the end of the photograph in the horizontal and vertical directions, and the points where the line segments intersected the secondary α phase were counted. Thereafter, the average interval of the secondary α phase was calculated from (total length of line segments) ÷ (total number of counts). FIG. 1 is a schematic diagram showing a method for calculating the average interval between secondary α phases. The intersection points X1 to X5 between the line segment 1 and the secondary α phase P were counted. In addition, in FIG. 1, the state about one of the line segments drawn five is shown.

  In rare cases, there may be an extremely fine α phase or an extremely fine β phase region at the time of measurement. However, the α phase / β whose equivalent circle diameter is counted as 5 nm or more by image analysis software. Phases were counted. Here, in calculating the equivalent circle diameter, in the case of a secondary α phase passing through the intersections X4 and X5 in FIG. 1, the region of the β phase (white) included in the secondary α phase has an equivalent circle diameter. Not calculated (ie, the equivalent circle diameter was determined from the area of the black region only)

(2) Measurement of area ratio of coarse α phase The forged material sample was observed with an optical microscope (OLYMPUS, GX71). In the observation, 10 photographs were taken at random with 400 times magnification under each condition. Thereafter, the particle size and aspect ratio of each primary α phase contained in 10 photographs were determined by image analysis (image analysis software; Image-Pro Plus, manufactured by Nippon Roper). The primary α phase is gradually constricted (dented) and further divided by forging and heat treatment, but the primary α phases that overlap each other even if constricted are counted as one primary α phase. By this count, it was determined whether or not the area ratio of the primary α phase having a particle diameter of 5 μm or more and an aspect ratio of 2 or more was 1% or less.

(3) Measurement of area ratio of primary α-phase The area ratio of the primary α-phase was determined by image analysis (image analysis software; Image-Pro Plus, manufactured by Nippon Roper Co., Ltd.) for the 400 × optical micrograph. The primary α phase was targeted for those with an equivalent circle diameter of 0.5 μm or more. By this image analysis, it was determined whether or not the area ratio of the primary α phase having a particle size of 0.5 μm or more was more than 0% and 20% or less.
As described above, the primary α phase has an equivalent circle diameter of 0.5 μm or more in an optical micrograph at a magnification of 400 times.

(4) Aspect ratio of β phase between secondary α phases The average aspect ratio of β phases was determined by image analysis using the above five SEM photographs. Depending on the observation field, an extremely fine β phase or an extremely coarse β phase is rarely observed, but a β phase having an equivalent circle diameter of 0.01 μm to 1.0 μm was analyzed.

In an actual forging product, at the thickest place of the forged product (that is, the place where the maximum inscribed circle is drawn), the surface layer side of the inscribed circle (position 10mm to 20mm deep from the outermost layer of the test piece) And the central part must be evaluated and both must satisfy the provisions of the present invention. That is, since the mechanical characteristics and material structure may vary from the surface layer side to the center of the maximum inscribed circle, the surface layer side and the center part are evaluated and judged.
The evaluation results are shown in Table 2.

Test material No. 1 to 3, 6, 8, and 10 all satisfy the Mo equivalent of the present invention, and are manufactured using the above preferable manufacturing conditions. It satisfied the provisions of the present invention and was excellent in strength, ductility and toughness.
However, the test material No. In No. 8, since the heating temperature of the aging treatment is higher than the preferable temperature range, the average interval of the secondary α phase exceeds 250 nm, and the 0.2% proof stress is slightly lower than other test materials. became.

Test material No. In No. 4, since the heating temperature of the aging treatment was lower than the preferable temperature range, the aspect ratio of the β phase between the secondary α phases was less than 2.0, and the elongation and fracture toughness were inferior.
Test material No. No. 5 had a lower temperature rise rate in the solution treatment than the preferred speed range, so the β phase aspect ratio between the secondary α phases was less than 2.0, and the fracture toughness was poor.
Test material No. No. 7, since the cumulative strain amount ε in the forging process was small, the area ratio of the coarse α phase exceeded 1%, and the elongation was inferior.
Test material No. No. 9 has a lower heating temperature in the solution treatment than the preferred temperature range, and the cooling rate after the solution treatment is larger than the preferred speed range, so that the area ratio of the primary α phase exceeds 20%, and the secondary α The aspect ratio of the β phase between the phases was less than 2.0, and the fracture toughness was poor.

P Secondary α phase X1, X2, X3, X4, X5 Intersection l Line segment

Claims (3)

When the content (mass%) of the element X is [X], it is a titanium alloy forging made of a titanium alloy having a Mo equivalent [Mo] _eq represented by the following formula (1) of 10 or more and less than 13. And
[Mo] _eq = [Mo] + [Ta] / 5 + [Nb] /3.6+ [W] /2.5+ [V] /1.5+1.25 [Cr] +1.25 [Ni] +1.7 [ Mn] +1.7 [Co] +2.5 [Fe] (1)
The area ratio of the primary α phase having a particle size of 5 μm or more and an aspect ratio of 2 or more is 1% or less,
The area ratio of the primary α phase having a particle size of 0.5 μm or more is more than 0% and 20% or less,
A titanium alloy forging material, wherein the aspect ratio of β phase between secondary α phases is 2.0 or more.   The titanium alloy forging according to claim 1, wherein an average interval between the secondary α phases is 250 nm or less.   The titanium alloy contains V: 9.0 to 11.0% by mass, Al: 2.6 to 3.4% by mass, Fe: 1.6 to 2.22% by mass, the balance being Ti and inevitable The titanium alloy forging material according to claim 1 or 2, wherein the titanium alloy forging material is an impurity.

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