JP4901135B2 - Titanium alloy member and manufacturing method thereof - Google Patents

Description

  The present invention relates to a titanium alloy member such as a titanium alloy spring and a manufacturing method thereof.

  Titanium is superior to iron in physical properties necessary as a structural member or functional member. Specifically, the density of titanium is lower than that of iron, and the strength such as tensile strength against specific gravity is high. Titanium has a Young's modulus about half that of iron and exhibits excellent elastic properties. For this reason, by using titanium, it is possible to form a structural member or functional member that is light, high in strength, and rich in elasticity. Moreover, it is possible to further improve these characteristics by adding various elements to titanium to form a titanium alloy.

  Despite these advantages, structural members and functional members using titanium or titanium alloys have been used only for special purposes such as aircraft and golf club shafts. This is because the cost of obtaining titanium and titanium alloys has been higher than that of iron.

  However, in recent years, a method for producing a titanium alloy at a low cost has been developed, and cost restrictions when using the titanium alloy as a structural member or a functional member are being solved. For this reason, taking advantage of the above-mentioned titanium, it has been studied to use a titanium alloy for products in various fields.

  In particular, when a spring (hereinafter referred to as a “titanium alloy spring”) is formed using a titanium alloy, the weight per unit length of the wire constituting the spring can be reduced because the density is low. Moreover, since the Young's modulus is small, the number of turns of the spring can be reduced, and the height of the spring necessary for obtaining the same amount of expansion and contraction and the total length of the wire constituting the spring can be shortened. For this reason, the titanium alloy spring has an equivalent function and can reduce the weight by about 60% compared to a spring made of steel (hereinafter referred to as “steel spring”). By using such a light spring for the suspension of the vehicle, it is possible to reduce the weight of the entire vehicle, accelerate the damping of the vibration, and improve the running performance of the vehicle.

  Conventionally, when manufacturing a steel spring, a projecting material such as a cut wire made of steel or a cast steel ball is projected onto the surface of the spring, and the surface is plastically deformed to generate a compressive stress in the vicinity of the spring surface. The process which improves durability of is performed. This process is called shot peening. When compressive stress is generated in the vicinity of the surface of the spring, even if the surface is damaged, the compressive stress acts in a direction in which the scratch does not expand. For this reason, it can suppress that a crack expands and it leads to destruction.

Even when a spring made of a titanium alloy is manufactured, it is known that durability is improved by performing shot peening as disclosed in Patent Documents 1 and 2, for example.
JP-A-5-195175 Japanese Patent Laid-Open No. 5-112857

  However, according to the research of the present inventor, it has been found that a spring having sufficient durability, particularly sufficient fatigue strength, cannot be obtained under the conditions of shot peening as disclosed in the above document.

  This invention is made | formed in view of the above-mentioned problem, The objective is to provide the titanium alloy member excellent in durability, and its manufacturing method.

  The titanium alloy member of the present invention has a compressive stress of 270 MPa or more within a depth of about 100 μm from the surface. This compressive stress is based on the measurement result of the residual stress by the X-ray method using a V tube.

  In a preferred embodiment, the titanium alloy member includes a surface region from the surface to a depth of about 100 μm and an inner region located inside the surface region, and the surface region is altered by having more α phase than the inner region. The ratio of the altered layer in the surface region is 10 vol% or less.

  In a preferred embodiment, the surface has a maximum surface roughness Rt of 20 μm or less.

  In a preferred embodiment, the titanium alloy member contains 50 vol% or more β-phase at room temperature.

  In a preferred embodiment, the titanium alloy member is a spring.

  In a preferred embodiment, the titanium alloy member is a vehicle suspension spring.

  In a preferred embodiment, the titanium alloy member is any one selected from an engine valve spring, an engine connecting rod, and an aircraft structural component.

  The engine according to the present invention includes a titanium alloy member having the above-described configuration.

  A vehicle according to the present invention includes a titanium alloy member having the above-described configuration.

  The titanium alloy member manufacturing method of the present invention includes a step (A) of preparing a shaped titanium alloy member, a step (B) of performing shot peening on the shaped titanium alloy member using a first projection material, and the step. A step (C) of mechanically or physically removing at least a part of the altered layer generated in the surface region of the shaped titanium alloy member by (B).

  In a preferred embodiment, the step (C) is performed by projecting a second projection material having a hardness higher than that of the first projection material onto the surface of the shaped titanium alloy member.

  In a preferred embodiment, the second projection material has a Vickers hardness of 1000 or more.

In a preferred embodiment, the second projection material contains SiO ₂ .

  In a preferred embodiment, in the method for producing a titanium alloy member of the present invention, the titanium alloy member is removed from the surface to a depth of about 20 μm to about 40 μm by the step (C).

  In a preferred embodiment, the shaped titanium alloy member has a Vickers hardness of 370 to 470.

  In a preferred embodiment, the step (A) includes a step (A1) of obtaining a formed titanium alloy member having a coil shape by winding a wire made of a titanium alloy, and a step of applying an aging treatment to the formed titanium alloy member ( A2).

  In a preferred embodiment, the step (B) is performed by projecting the first projection material onto the shaped titanium alloy member by any one of centrifugal force, compressed air, and water pressure.

  The titanium alloy member of the present invention hardly includes a deteriorated layer in which a defect serving as a starting point of fracture is generated, and compressive stress is generated in the vicinity of the surface of the titanium alloy member. For this reason, the titanium alloy member of the present invention exhibits high fatigue strength.

  The inventor of the present application examined the cross section of the titanium alloy spring in order to investigate the cause of insufficient fatigue strength even if the conventional shot peening is applied to the titanium alloy spring. Fig.1 (a) is a photograph which shows the cross section of a steel spring, FIG.1 (b) is a photograph which shows the cross section of a titanium alloy spring. Each of the springs is subjected to a conventional shot peening process used to improve fatigue strength.

  As is apparent from a comparison of FIGS. 1A and 1B, a defected region not found in the steel spring is seen near the surface of the titanium alloy spring. As a result of detailed examination of the cross section of the titanium alloy spring, the following findings were obtained.

  Fig.2 (a) has shown typically the cross section of the titanium alloy spring shown in FIG.1 (b). As a result of detailed analysis and examination of the cross section, it was found that a deteriorated layer 2 having defects 3 was formed in the vicinity of the surface of the titanium alloy spring subjected to shot peening.

  A titanium alloy has a hexagonal close-packed (HCP) structure at room temperature, but when it is at a temperature of 885 ° C. or higher, or when it contains Mo, V, Nb, Ta, etc. as an alloy element, body-centered cubic (BCC) Take the structure. The HCP structure and the BCC structure are called an α phase and a β phase, respectively, and an alloy having a BCC structure at room temperature is called a β alloy. In general, since the β phase is more workable, the titanium alloy spring is made of a β alloy.

  When the projection material is projected onto the surface of the titanium alloy spring, the kinetic energy of the projection material is consumed in the form of surface dent formation and surface heat generation. As a result of the analysis, in the altered layer 2, the β phase is transformed into an α phase by the energy (deformation and heat) generated by shot peening, and most of the altered layer 2 is constituted by the α phase of the HCP structure. I understood. The thickness of the altered layer 2 was about 20 μm to about 40 μm. The region 1 existing inside the altered layer 2 is not affected by heat and is made of a β phase or an alloy containing a lot of β phases. That is, the altered layer 2 contains more α phase than the region 1.

  FIG. 2B schematically shows a profile in the depth direction of the internal residual stress in the cross section shown in FIG. As shown in FIG. 2B, the altered layer 2 is formed on the surface, and the compressive residual stress increases as the depth increases. The compressive stress is maximum in the region 1 (about 200 μm) inside the deteriorated layer.

  When a fatigue test was performed on the titanium alloy spring shown in FIG. 1 (b), it was found that the fatigue strength was lowered. This is because the defect 3 generated in the deteriorated layer 2 reaches the interface 4 with the region 1, so that stress concentrates on the interface 4 between the deteriorated layer 2 and the region 1 where no transformation occurs. It is inferred that the cause is that the fracture spreads into the region 1 as a starting point.

  From these facts, it is considered that by removing the deteriorated layer 2, it is possible to remove the defect 3 that is the starting point of the fracture and to provide a region 1 in which a relatively large compressive stress remains in the vicinity of the surface. Thereby, the fatigue strength of a titanium alloy spring can be improved using the compressive stress near the surface of the spring.

  Hereinafter, the titanium alloy member of the present invention and the manufacturing method thereof will be specifically described.

  Fig.3 (a) has shown typically the structure of the surface vicinity of the titanium alloy member by this invention. FIG. 3B shows a profile in the depth direction of the residual stress in the structure shown in FIG. Titanium alloy member 10 includes a surface region 11b and an internal region 11a located therein. The surface region 11b is a region within a depth of about 100 μm from the surface 11s of the titanium alloy member 10, and has a compressive stress of 270 MPa or more. This compressive stress is caused by the shot peening process, as will be described in detail below. The altered layer generated on the surface by shot peening is removed from the titanium alloy member 10.

  When the inventor of the present application has conducted a detailed study, the fatigue strength of the titanium alloy member 10 is increased because a compressive stress of 270 MPa or more is generated in a region shallower than 100 μm from the surface 11s of the titanium alloy member 10, that is, the surface region 11b. It has been experimentally confirmed that it improves. However, considering the yield point of the titanium alloy member 10, the compressive stress is preferably 1100 MPa or less. The stress referred to here is the β-phase residual stress of the titanium alloy member 10 measured by the X-ray method using a V tube. However, the stress value by the X-ray method does not match the value by the strain gauge method which is a general stress measurement method. For this reason, the stress by the X-ray method is verified using the strain gauge method, and the stress value by the X-ray method is corrected based on the verification.

  FIG. 3B shows the profile of FIG. 2B with a broken line. As apparent from FIG. 3 (b), the stress peak moves closer to the surface than the stress peak obtained by conventional shot peening, and the compressive stress becomes maximum at a depth of about 100 μm. The profile of compressive stress due to shot peening depends on the mass of the projection material and the projection speed. Generally, in order to generate a large compressive stress, it is necessary to use a heavy projecting material, and the energy when the projecting material collides with an object also increases. For this reason, the energy by the projection material propagates deep inside the object, and the stress peak becomes deep. In other words, when shot peening is performed once using a condition that forms a large compressive stress, the maximum value of the stress is located deep from the surface, and a large stress is relatively shallow from the surface as in the present invention. It is difficult to form in.

  In order to define the compressive stress in the vicinity of the surface, a region shallower than 100 μm from the surface of the titanium alloy member 10 is called a surface region 11b. However, the difference in composition and physical properties that separate the surface region 11b and the internal region 11a is as follows. It has not actually occurred. In the example shown in FIG. 3 (b), the compressive stress is greatest near the boundary between the surface region 11b and the inner region 11a, the stress rapidly decreases inside the inner region 11a than the boundary, and thereafter reaches a substantially constant value. Take.

  The entire titanium alloy member 10 including the surface region 11b and the internal region 11a preferably includes 50 vol% or more of the β phase, and the entire titanium alloy member 10 may be configured of the β phase. That is, an α + β alloy or a β alloy containing 50 vol% or more of the β phase may be used. Such an alloy contains one or more elements such as Al, Fe, Mo, Sn, V, Zr, Si, Cr, Nb, and O. Typical compositions include Ti-1.5Al-4.5Fe-6.8Mo-0.15O, Ti-13V-11Cr-3Al, Ti-8Mo-8V-2Fe-3Al, Ti-3Al-8V-6Cr. -4Mo-4Zr, Ti-11.5Mo-6Zr-4.5Sn, Ti-15Mo-5Zr, Ti-15Mo-5Zr-3Al, and the like.

  As described above, it is preferable that the altered layer generated in the shot peening process is removed, and the altered region is not included in the surface region 11b. However, if the deteriorated layer does not remain in the surface region 11a at a rate exceeding 10 vol%, the defects 3 that cause stress concentration are almost removed from the titanium alloy member 10, and the titanium alloy member 10 has high fatigue strength.

  The surface 11s of the titanium alloy member 10 preferably has a maximum surface roughness Rt of 20 μm or less. By smoothing the surface 11s, stress concentration on the surface 11s can be relaxed, and the fracture of the titanium alloy member 10 due to fatigue can be suppressed. In particular, if even one portion of the surface 11s has a rough portion, stress concentrates on that portion. Therefore, by setting the maximum surface roughness to the above-mentioned value, in addition to the effect of removing the altered layer, relaxation of stress concentration Can be achieved.

  Next, an example of a method for producing a titanium alloy member according to the present invention will be described with reference to FIGS. In the following description, a method for manufacturing a titanium alloy spring will be described.

  First, the wire which comprises a spring is prepared (step 21). Cold drawing or the like is performed in advance so that the wire has a desired diameter. Of the above-described titanium alloy materials, it is preferable to use a β alloy having excellent workability or an α + β alloy having a small α phase. The prepared wire is formed into a desired shape (that is, wound) by a forming method such as coiling, and a formed spring that is a formed titanium alloy member is obtained (step 22). Thereafter, the molded spring is subjected to an aging treatment (step 23).

  Next, a shot peening process is performed to generate a compressive stress near the surface of the molded spring (step 24). As shown to Fig.5 (a), the projection material 31 is projected on the surface 30s of the spring 30, and a hollow is formed in the surface 30s. As the projection material 31, it is preferable to use a cast steel shot ball or a cut wire from the viewpoint of cost. The size, the projection speed, and the projection density of the projection material 31 are appropriately selected according to the size and application of the titanium alloy member to be manufactured and the composition of the alloy constituting the titanium alloy member. The projection material can be projected using a known method such as centrifugal force, compressed air, and water pressure. As shown in FIG. 5A, the altered layer 30b in which the α phase is contained in the vicinity of the surface 30s of the spring 30 in the vicinity of the surface 30s of the spring 30 as compared with the internal region 30a and a defect is generated is formed. In addition, compressive stress is generated in the deteriorated layer 30b and the inner region 30a by the shot peening process. The above conditions may be changed and shot peening may be performed a plurality of times so that the titanium alloy member has an optimal compressive stress profile in the depth direction depending on the application. In general, by performing shot peening using a large projection material 31, a compressive stress can be generated deep inside the titanium alloy member.

  Next, the deteriorated layer 30b is removed (step 25 in FIG. 4). When removing the altered layer 30b, it is preferable to remove the altered layer 30b while further applying compressive stress to the internal region 30a. Moreover, it is preferable that the surface roughness of the surface of the spring 30 is reduced after removing the deteriorated layer 30b. As long as these conditions are satisfied, the altered layer 30b may be removed by any method. However, in order to remove the altered layer 30b while applying compressive stress, it is preferable to remove the altered layer 30b mechanically or physically.

When the altered layer 30b is mechanically removed, it is more preferable to remove the altered layer 30b by shot peening using a projection material having a small particle diameter. Since titanium alloys generally have Vickers hardness of about 370 to 470, it is preferable to use a projection material having a hardness higher than this value and excellent in abrasiveness. For example, it is preferable to use a projection material made of SiO ₂ having a specific gravity of about 2.5 and a Vickers hardness of about 1000 and an average particle diameter of about 50 μm or less. Since such a projection material has a small particle size and specific gravity, energy by collision is small, and projections do not newly form irregularities on the surface of the spring 30, but a certain amount of stress can be applied to the internal region 30a by collision. . Further, since the projection material made of SiO ₂ has a spherical shape but high hardness, it is considered that the polishing ability is high. On the other hand, the projection material made of, for example, cast steel used in the first shot peening has lower hardness than the projection material made of SiO ₂ . For this reason, in shot peening, only the titanium alloy member is plastically deformed, and the deteriorated layer 30b and the inner region 30a are hardly polished.

As shown in FIG. 5B, the altered layer 30 b is removed by projecting the projecting material 32 made of SiO ₂ onto the spring 30. At this time, the altered layer 30b may be completely removed, and a part of the inner region 30a may be removed. Further, even if a part of the deteriorated layer 30b remains, the ratio of the deteriorated layer 30b in the surface region having a predetermined depth from the surface may be equal to or less than the above-described value. The projecting material 32 selectively collides with the large convex portion of the surface 30s of the spring 30 and is polished. Thereby, the surface roughness of the surface 30s becomes small. As a result, as shown in FIG. 5C, the altered layer 30b is removed, and a spring 30 ′ in which the inner region 30a is exposed on the surface 30s ′ is obtained (step 26 in FIG. 4).

  In the titanium alloy spring manufactured in this way, the deteriorated layer in which the defect that causes fracture is generated is removed, and compressive stress is generated in the vicinity of the surface of the spring. Moreover, since the surface roughness is small, the stress concentration is alleviated. For this reason, high fatigue strength is shown.

  In the above embodiment, the titanium alloy member of the present invention has been described by taking a spring as an example. The titanium alloy spring of the present invention can be suitably used for suspension springs for vehicles such as two-wheeled vehicles and four-wheeled vehicles. The titanium alloy spring of the present invention is also suitable for engine valve springs. Moreover, since the titanium alloy member of the present invention is excellent in fatigue strength, it can be suitably used for elastic members and structural members other than springs that receive repeated stress. For example, it can be suitably used as an aircraft structural component such as a connecting rod for connecting an engine piston and a crankshaft, an engine valve, and the like.

  Hereafter, the titanium alloy member by this invention is created and a part of result of having evaluated the characteristic etc. is shown. In the example shown below, a titanium alloy having a composition of Ti-1.5Al-4.5Fe-6.8Mo-0.15O is used for a motorcycle having a coil diameter of 100 mm and a height of 150 mm using a wire having a diameter of 12 mm. A suspension spring was produced.

  The spring was subjected to aging treatment at 520 ° C. for 3 hours, and then shot peening treatment and removal of the deteriorated layer were performed under the following conditions. Moreover, as a comparative example, a spring was produced by the same procedure and only the shot peening process was performed. In this embodiment, the shot peening process is performed twice by changing the projection material. This is to apply the internal stress more evenly.

  FIGS. 6A and 6B are photographs showing cross sections of the spring of the present invention and the spring of the comparative example. As is clear from FIG. 6A, the spring of the present invention has a uniform structure from the surface to the inside. On the other hand, it can be seen from FIG. 6B that a deteriorated layer having many defects is formed in the vicinity of the surface in the spring of the comparative example. Further, the surface roughness of the spring of the present invention is smaller than that of the spring of the comparative example.

  FIG. 7 is a graph showing the results of measuring the stress in the depth direction of the spring of the present invention and the spring of the comparative example. The stress was measured by measuring the β-phase residual stress by the X-ray method using a V tube. As a measuring device, an X-ray stress measuring device PSPC-MSF type manufactured by Rigaku Corporation was used. As described above, correction by the strain gauge method is performed.

  As shown in FIG. 7, in the spring of the present invention, a compressive stress is suddenly generated from the surface, and a compressive stress of about 290 MPa is generated at a depth of about 100 μm from the surface. In a deeper portion, the compressive stress is gradually relaxed, and in a region deeper than about 400 μm, a constant value of 220 MPa is taken. This is considered to be the precipitation stress of α phase.

  On the other hand, in the comparative example, a compressive stress is gradually generated from the surface, and a compressive stress of about 310 MPa is generated at a depth of about 200 μm. In a deeper portion, the compressive stress is gradually relaxed, and in a region deeper than about 400 μm, a constant value of 260 MPa is taken.

  As is apparent from FIG. 7, the spring of the present invention generates a greater compressive stress near the surface.

  FIG. 8 shows the results of a rotating bending fatigue test performed on the spring of the present invention and the spring of the comparative example. As is apparent from FIG. 8, it can be seen that the number of repetitions until the spring of the present invention breaks is about 10 times that of the comparative example, and the fatigue strength is improved.

  Thus, in the spring of the present invention, compared with the spring of the comparative example, the deteriorated layer is completely removed, the surface is free of defects, the surface roughness is small, and a large compressive stress is suddenly generated from the surface. It has the feature of being. Such characteristics are thought to contribute to the improvement of fatigue strength.

  Table 2 below shows the results of a durability evaluation test performed by changing the maximum compressive stress within a depth of about 100 μm from the surface. As can be seen from Table 2, excellent durability can be obtained by generating a compressive stress of 270 MPa or more within a depth of about 100 μm from the surface.

  FIG. 9 shows a motorcycle 100 equipped with a titanium alloy spring according to the present invention as a suspension spring.

  In the motorcycle 100, a head pipe 102 is provided at the front end of the main body frame 101. A front fork 103 is attached to the head pipe 102 so as to be able to swing in the left-right direction of the vehicle. A front wheel 104 is rotatably supported at the lower end of the front fork 103.

  A seat rail 106 is attached so as to extend rearward from the upper rear end of the main body frame 101. A seat 107 is provided on the seat rail 106.

  An engine (internal combustion engine) 109 is held at the center of the main body frame 101. An exhaust pipe 110 is connected to the exhaust port of the engine 109, and a muffler 111 is attached to the rear end of the exhaust pipe 110.

  A pair of rear arms 113 extending rearward are attached to the rear end of the main body frame 101. The rear arm 113 is pivotally supported by the seat pillar 114. A rear wheel 115 is rotatably supported at the rear end of the rear arm 113.

  A rear arm 113 arranged on the left side of the motorcycle 100 and a rear arm (not shown here) arranged on the right side are connected to each other by a connecting member 116 extending in the width direction of the vehicle.

  The connecting member 116 and the seat rail 106 are connected by a shock absorber 120, and the rear arm 113 and the rear wheel 115 are suspended from the vehicle body by the shock absorber 120.

  The shock absorber 120 is enlarged and shown in FIG. The shock absorber 120 includes a hydraulic cylinder 121 and a spring 122 that is externally fitted to the cylinder 121. The shock and vibration transmitted from the rear wheel 115 are attenuated by the shock absorber 120 including the spring 122.

  Since the motorcycle 100 includes the titanium alloy spring according to the present invention having excellent fatigue strength as the spring 122 of the shock absorber 120, suitable performance can be obtained.

  Although the motorcycle 100 provided with the titanium alloy spring according to the present invention as a suspension spring is illustrated here, suitable performance can be obtained even when the titanium alloy spring according to the present invention is used as an engine valve spring. Moreover, even if the titanium alloy member according to the present invention is used as a connecting rod for an engine, suitable performance can be obtained. These suspension springs, engine valve springs, connecting rods and the like are also collectively referred to as components for internal combustion engines.

  The titanium alloy member and the manufacturing method thereof according to the present invention can be applied to various fields as an elastic member such as a spring or a structural member. In particular, since it is lightweight, high in strength, and excellent in durability, it is suitably used in the fields of transportation equipment such as vehicles and aircraft, and construction.

(A) And (b) is a photograph which shows the cross-sectional structure of a steel spring, and the cross-sectional structure of the conventional titanium alloy spring, respectively. (A) is a schematic diagram explaining the cross-sectional structure | tissue of the conventional titanium alloy spring, (b) has shown the stress distribution of the depth direction. (A) is a schematic diagram explaining the cross-sectional structure | tissue of the titanium alloy spring of this invention, (b) has shown the stress distribution of the depth direction. It is a flowchart which shows the manufacturing method of a titanium alloy spring. (A)-(c) is process sectional drawing which shows the manufacturing method of a titanium alloy spring. (A) And (b) is a photograph which shows the cross-sectional structure | tissue of the titanium alloy spring of this invention, and a comparative example, respectively. It is a graph which shows the stress distribution of the depth direction of the titanium alloy spring of this invention, and a comparative example. It is a graph which shows the result of the rotation bending fatigue test of the titanium alloy spring of this invention, and a comparative example. 1 is a side view schematically showing a motorcycle provided with a titanium alloy spring of the present invention. Fig. 10 is an enlarged view of a shock absorber provided in the motorcycle shown in Fig. 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Titanium alloy member 11a Internal region 11b Surface region 11s Titanium alloy member surface 30, 30 'Spring 30a Internal region 30b Alteration layer 30s, 30s' Spring surface 31, 32 Projection material 100 Motorcycle 120 Shock absorber

Claims (17)

A titanium alloy member having a maximum compressive stress of 270 MPa or more in a β phase within a depth of 100 μm from the surface. A surface region from the surface to a depth of 100 μm and an internal region located inside the surface region, the surface region including a modified layer having more α phase than the internal region, and the modified layer in the surface region The titanium alloy member according to claim 1, wherein the ratio is 10 vol% or less.   The titanium alloy member according to claim 1, wherein the surface has a maximum surface roughness Rt of 20 μm or less.   The titanium alloy member according to any one of claims 1 to 3, wherein the titanium alloy member includes a β phase of 50 vol% or more at room temperature.   The titanium alloy member according to any one of claims 1 to 4, wherein the titanium alloy member is a spring.   The titanium alloy member according to any one of claims 1 to 4, wherein the titanium alloy member is a suspension spring for a vehicle.   The titanium alloy member according to any one of claims 1 to 4, wherein the titanium alloy member is any one selected from an engine valve spring, an engine connecting rod, and an aircraft structural component.   An engine comprising the titanium alloy member according to any one of claims 1 to 4.   A vehicle comprising the titanium alloy member according to any one of claims 1 to 4. A step of preparing a formed titanium alloy member (A);
A step (B) of performing shot peening on the formed titanium alloy member using a first projecting material;
A step (C) of mechanically or physically removing at least a part of the altered layer generated in the surface region of the shaped titanium alloy member by the step (B);
The manufacturing method of the titanium alloy member containing this.   The said process (C) is a titanium alloy member manufacturing method of Claim 10 performed by projecting the 2nd projection material which has higher hardness than the said 1st projection material on the surface of the said shaping | molding titanium alloy member. .   The method for producing a titanium alloy member according to claim 11, wherein the second projection material has a Vickers hardness of 1000 or more. The second shot material, manufacturing method of the titanium alloy member according to claim 11 or 12 made of SiO _2. The method for producing a titanium alloy member according to any one of claims 10 to 13, wherein the formed titanium alloy member is removed from the surface to a depth of 20 µm to 40 µm by the step (C).   The method for manufacturing a titanium alloy member according to any one of claims 10 to 14, wherein the formed titanium alloy member has a Vickers hardness of 370 to 470. The step (A)
Winding a wire made of a titanium alloy to obtain a formed titanium alloy member having a coil shape (A1);
A step (A2) of performing an aging treatment on the shaped titanium alloy member;
The manufacturing method of the titanium alloy member in any one of Claim 10 to 15 containing.   The titanium alloy according to any one of claims 10 to 16, wherein the step (B) is performed by projecting the first projecting material onto the formed titanium alloy member by any one of centrifugal force, compressed air, and water pressure. Manufacturing method of member.