JP2017218661A - Titanium alloy forging material - Google Patents
Titanium alloy forging material Download PDFInfo
- Publication number
- JP2017218661A JP2017218661A JP2016116350A JP2016116350A JP2017218661A JP 2017218661 A JP2017218661 A JP 2017218661A JP 2016116350 A JP2016116350 A JP 2016116350A JP 2016116350 A JP2016116350 A JP 2016116350A JP 2017218661 A JP2017218661 A JP 2017218661A
- Authority
- JP
- Japan
- Prior art keywords
- phase
- less
- titanium alloy
- primary
- forging
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Landscapes
- Forging (AREA)
Abstract
Description
本発明は、チタン合金鍛造材に関し、特に、ニア（ｎｅａｒ）β型チタン合金鍛造材に関する。 The present invention relates to a titanium alloy forging, and more particularly to a near β-type titanium alloy forging.
航空機用部品等には、軽量で高強度であることに加えて、高延性、高靭性等であることが要求されることから、α＋β型チタン合金やニアβ型チタン合金が多く使用されている。α＋β型チタン合金は、主相である稠密六方晶（ｈｃｐ構造）のα相と体心立方晶（ｂｃｃ構造）のβ相とが室温で安定に共存して、強度と延性等のバランスに優れており、また、β変態点（Ｔβ）以上の温度域でβ相単相となる。ニアβ型チタン合金は、α＋β型チタン合金と高強度なβ型チタン合金との中間的な金属組織を有しており、α＋β型チタン合金と同様にα相とβ相とが共存する。これらのチタン合金の鍛造材には、Ｔβ以上の温度に到達しないようにＴβ未満の温度域（α＋β二相域）に加熱して鍛造するα＋β鍛造によるものと、Ｔβ以上の温度域（β単相域）に加熱して鍛造するβ鍛造によるものとがある。α＋β鍛造材とβ鍛造材では、形成される材料組織は全く異なり、それに伴い材料特性が異なることが知られている。 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.
チタン合金の中でも、高強度なニアβ型チタン合金として、Ti-10V-2Fe-3Al合金などが知られている。Ti-10V-2Fe-3Al合金は、その特性をさらに改良するために、いくつかの改良技術が開発されている。例えば、特許文献１には、ニアβ型チタン合金の高強度化特性を維持しつつ冷間加工性を改善する加工前処理方法が開示されている。また、特許文献２には、強度・靭性に優れたニアβ型チタン合金を得るための処理方法が開示されている。 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.
しかしながら、航空機用部品には、更なる強度、延性、靱性等の機械的特性の向上が要求されている。一般に高強度化を図ると、靱性や延性は低下する傾向にある。特許文献１および特許文献２に開示された処理方法は、機械的特性にまだ改良の余地を有するものであった。 However, aircraft parts are required to further improve mechanical properties such as 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 mechanical properties.
さらに、特に大型のチタン合金鍛造材においては、一般的な製造条件では素材内部の加熱速度や冷却速度が低下する等の理由により、優れた機械的特性、特に延性や破壊靭性を達成することが困難であった。そのため、延性や破壊靭性を一定レベルに確保した上で安定して高強度化を達成したいという要望が存在していた。 Furthermore, particularly for large titanium alloy forgings, it is possible to achieve excellent mechanical properties, particularly ductility and fracture toughness, due to reasons such as reduced heating and cooling rates inside the material under general production conditions. It was difficult. For this reason, there has been a demand for achieving high strength stably while ensuring ductility and fracture toughness at a certain level.
本発明は、前記問題点に鑑みてなされたものであり、延性と破壊靭性を保持しつつ、強度に優れたチタン合金鍛造材を提供することを課題とする。 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, maintaining a ductility and fracture toughness.
本発明者らは素材内部の機械的特性を安定して確保する方法について鋭意研究した。その結果、一次α相を微細化し、量を低減させるだけでなく、長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満の細長い形状をした特定のα相を低減させること、二次α相および前記特定のα相の間隔を制御することによって、上記課題を解消し得ることを見出して、本発明に到達したものである。 The present inventors have intensively studied on a method for stably securing the mechanical characteristics inside the material. As a result, not only the primary α phase is refined and the amount is reduced, but also the specific α phase having an elongated shape with a major axis of 2 μm or more, a minor axis of 0.1 μm or more and less than 0.5 μm is reduced, and the secondary α It has been found that the above-mentioned problems can be solved by controlling the phase and the interval between the specific α phases, and the present invention has been achieved.
すなわち、本発明に係るチタン合金鍛造材は、元素Ｘの含有量（質量％）を[Ｘ]としたときに、下記式（１）で表されるＭｏ当量［Ｍｏ］ｅｑが１０以上１３未満であるチタン合金からなるチタン合金鍛造材である。
[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）
本発明に係るチタン合金鍛造材は、α相とβ相の面積率の合計が９９％以上であり、一次α相の面積率が２０％以下であり、一次α相の平均粒径が２．５μｍ以下である。また、本発明に係るチタン合金鍛造材は、長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相の面積率が３％以下である。さらに、本発明に係るチタン合金鍛造材は、二次α相および前記長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相の平均間隔が１００〜２００ｎｍである。
That is, in the titanium alloy forged material 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 It is a titanium alloy forging material 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 titanium alloy forging according to the present invention has a total area ratio of α phase and β phase of 99% or more, a primary α phase area ratio of 20% or less, and an average particle diameter of the primary α phase of 2. 5 μm or less. In the titanium alloy forged material according to the present invention, the area ratio of the α phase having a major axis of 2 μm or more, a minor axis of 0.1 μm or more and less than 0.5 μm is 3% or less. Further, in the titanium alloy forged material according to the present invention, the average interval between the secondary α phase and the α phase having the major axis of 2 μm or more, the minor axis of 0.1 μm or more and less than 0.5 μm is 100 to 200 nm.
かかる構成のチタン合金鍛造材であれば、延性、破壊靭性および強度のいずれにも優れたものとすることができる。 A titanium alloy forged material having such a configuration can be excellent in all of ductility, fracture toughness and strength.
本発明のチタン合金鍛造材は、延性と破壊靭性を保持しつつ、強度に優れたものとすることができる。 The titanium alloy forged material of the present invention can be excellent in strength while maintaining ductility and fracture toughness.
以下、本発明の実施の形態について詳細に説明する。
本発明に係るチタン合金鍛造材は、航空機用部品等に用いられ得るチタン合金鍛造材であって、鍛造や熱処理によって金属組織を制御することで、機械的特性に優れたものとすることができる。
Hereinafter, embodiments of the present invention will be described in detail.
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 can have excellent mechanical properties by controlling the metal structure by forging or heat treatment. .
〔チタン合金〕
本発明に係るチタン合金は、元素Ｘの含有量（質量％）を[Ｘ]としたときに、下記式（１）で表されるＭｏ（モリブデン）当量［Ｍｏ］ｅｑが１０以上１３未満である。
[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当量は、チタン合金の各相の安定性を示す指標として、一般的に使用されているものである。Ｍｏ当量の詳細については、G. Lutjering & J. C. Williams, "Titanium", Second Edition, Springer-Verlag, Berlin, 2010, p30または古原、牧, 金属, vol.66（1996）, No.4, p289 等において説明がなされている。
Ｍｏ当量は、強度を確保するために１０以上の値は必要であり、より好ましくは１０．５以上である。一方、熱間鍛造性や延性を良好なものとするために１３未満に制御することが必要であり、より好ましくは１２．５以下である。
[Titanium alloy]
The titanium alloy according to the present invention has a Mo (molybdenum) equivalent [Mo] eq represented by the following formula (1) of 10 or more and less than 13 when the content (mass%) of the element X is [X]. is there.
[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.
上記のＭｏ当量の規定を満足するチタン合金として、ＡＭＳ４９８４に定められたTi-10V-2Fe-3Al合金がある。Ti-10V-2Fe-3Al合金の合金組成は、Ｖ：９．０〜１１．０質量％、Ａｌ：２．６〜３．４質量％、Ｆｅ：１．６〜２．２２質量％を含有し、残部はＴｉおよび不可避的不純物である。不可避的不純物としては、例えば、Ｃ：０．０５質量％以下、Ｎ：０．０５質量％以下、Ｏ：０．１３質量％以下、Ｈ：０．０１５質量％以下、Ｙ：０．００５質量％以下を含有する。ここで、Ｍｏ当量は、式（１）中でTi-10V-2Fe-3Al合金が含有しない元素については、含有量０として計算される。 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).
Ti-10V-2Fe-3Al合金の場合、β相の固溶強化やβ相を安定化させるために、Ｖ：９．０質量％以上、Ｆｅ：１．６質量％以上が必要であり、α相の固溶強化やα相を安定化させるためにＡｌ：２．６質量％以上が必要である。また、過剰な添加は熱間鍛造性や延性を損なう恐れがあるため、Ｖ：１１．０質量％以下、Ａｌ：３．４質量％以下、Ｆｅ：２．２２質量％以下に制御する。また、不可避不純物が増えると素材が脆化する恐れがあるため、上記の通り上限値以下に制御する。 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.
Ｍｏ当量が１０以上１３未満であるチタン合金としては、その他に、Ti-5Al-5V-5Mo-3Cr合金等を例示することができる。 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.
〔金属組織〕
本発明のチタン合金鍛造材はニアβ型チタン合金鍛造材であり、その金属組織は、主にα相とβ相からなり、α相は、一次α相と二次α相からなる。本発明のチタン合金鍛造材の金属組織は、一次α相の面積率が２０％以下であり、一次α相の平均粒径が２．５μｍ以下であり、長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相の面積率が３％以下である。また、本発明のチタン合金鍛造材の金属組織は、二次α相および前記長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相の平均間隔が１００〜２００ｎｍである。
以下、各特性について順次説明する。
[Metal structure]
The titanium alloy forged material of the present invention is a near β-type titanium alloy forged material, and its metal structure is mainly composed of an α phase and a β phase, and the α phase is composed of a primary α phase and a secondary α phase. The metal structure of the forged titanium alloy of the present invention has an area ratio of primary α phase of 20% or less, an average particle size of primary α phase of 2.5 μm or less, a major axis of 2 μm or more, and a minor axis of 0.1 μm or more. In addition, the area ratio of the α phase of less than 0.5 μm is 3% or less. Moreover, the metal structure of the forged titanium alloy of the present invention has an average interval between the secondary α phase and the α phase having the major axis of 2 μm or more, the minor axis of 0.1 μm or more and less than 0.5 μm of 100 to 200 nm.
Hereinafter, each characteristic will be sequentially described.
本発明のチタン合金鍛造材の金属組織は、実質的にα相およびβ相からなり、α相とβ相の面積率の合計は９９％以上である。更にα相は、一次α相と二次α相に分類される。二次α相とは、時効工程において析出してくるα相のことであり、一次α相とは、二次α相以外のα相のことである。α相およびβ相以外の組織としては、炭化物や介在物等を微量含有することがある。 The metal structure of the titanium alloy forged material of the present invention substantially consists of an α phase and a β phase, and the total area ratio of the α phase and the β phase is 99% or more. Furthermore, the α phase is classified into 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.
（一次α相、二次α相）
本発明のチタン合金鍛造材の金属組織において、一次α相と二次α相とは、粒径が異なる。そこで、倍率４００倍の光学顕微鏡を用いて観察したときのα相の粒径によって、一次α相と二次α相とを区別して規定することとする。すなわち、倍率４００倍の光学顕微鏡で観察したときに、粒径が０．５μｍ以上の閉じた領域のα相を一次α相と定義する。一次α相以外の領域は、二次α相およびβ相を含む領域となる。ここで、粒径は、円相当径として求められる。また、α相およびβ相以外の組織は除外している。
(Primary α phase, secondary α phase)
In the metal structure of the titanium alloy forged material of the present invention, the primary α phase and the secondary α phase have different particle sizes. Therefore, the primary α phase and the secondary α phase are distinguished and defined by the particle size of the α phase when observed using an optical microscope with a magnification of 400 times. That is, an α phase in a closed region having a particle size of 0.5 μm or more when observed with an optical microscope having a magnification of 400 times is defined as a primary α phase. The region other than the primary α phase is a region including the secondary α phase and the β phase. Here, the particle diameter is obtained as a circle-equivalent diameter. In addition, tissues other than α phase and β phase are excluded.
次に、上記の一次α相以外の領域を、倍率３万倍のＦＥ−ＳＥＭ（電界放射型走査電子顕微鏡）を用いて観察する。このとき、二次α相とβ相とは、相互に入り組んだ不規則な形状を有しているが、画像の色相から両者を区別して認識することができる。 Next, the region other than the primary α phase is observed using an FE-SEM (field emission scanning electron microscope) with a magnification of 30,000 times. At this time, the secondary α-phase and β-phase have irregular shapes intermingled with each other, but can be distinguished from each other based on the hue of the image.
（中間α相）
さらに、本発明者らの検討によると、粒径が０．５μｍ前後であって、細長い形状をしたα相が存在する。すなわち、光学顕微鏡のようなマクロレベル（例えば倍率４００倍）で確認される一次α相と、ＳＥＭのようなミクロレベル（例えば倍率３万倍）で確認される二次α相との中間付近のサイズ（例えばＦＥ−ＳＥＭにて倍率３千倍）であって、細長い形状をしたα相が存在する。このようなα相として、その代表的な寸法から、「長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相」を定義する。「長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相」を以下、適宜「中間α相」と簡略化して記載する。
(Intermediate α phase)
Further, according to the study by the present inventors, there is an α phase having a particle size of about 0.5 μm and an elongated shape. That is, in the vicinity of the middle between a primary α phase confirmed at a macro level (for example, 400 times magnification) like an optical microscope and a secondary α phase confirmed at a micro level (for example, 30,000 times magnification) like SEM. There is an α phase having a size (for example, a magnification of 3,000 by FE-SEM) and an elongated shape. As such an α phase, “α phase having a major axis of 2 μm or more, a minor axis of 0.1 μm or more and less than 0.5 μm” is defined from its typical dimensions. The “α phase having a major axis of 2 μm or more, a minor axis of 0.1 μm or more and less than 0.5 μm” is hereinafter simply abbreviated as “intermediate α phase”.
ここで、「短径」は、α相のうち、画像解析ソフトの「直径（最小）」として求められる。すなわち「α相の領域の重心を通り、かつα相の領域の外周の２点を結ぶ径のうちで最小のもの」である。一方、「長径」は、α相の領域内で取りうる最大の線分である。 Here, “minor axis” is obtained as “diameter (minimum)” of the image analysis software in the α phase. That is, “the smallest of the diameters passing through the center of gravity of the α phase region and connecting two points on the outer periphery of the α phase region”. On the other hand, the “major axis” is the maximum line segment that can be taken within the α-phase region.
中間α相は、細長い形状をした閉じた領域のα相であり、一次α相か二次α相のいずれかに属するものである。中間α相は、短径（最小直径）が０．５μｍ未満であるが、粒径（円相当径）としては０．５μｍを超えることもある。そのため、中間α相には、粒径から判定すると、一次α相に属するものもあったり、二次α相に属するものもあったりする。 The intermediate α phase is a closed region α phase having an elongated shape, and belongs to either the primary α phase or the secondary α phase. The intermediate α phase has a short diameter (minimum diameter) of less than 0.5 μm, but may have a particle diameter (equivalent circle diameter) of more than 0.5 μm. For this reason, some intermediate α phases belong to the primary α phase and some belong to the secondary α phase when judged from the particle diameter.
（中間α相の面積率）
本発明者らの検討によると、上記の中間α相の面積率が、延性、破壊靭性、強度に関わっていることが判明した。
チタン合金鍛造材の延性と破壊靭性を確保しつつ強度を高めるために、中間α相の面積率を３％以下に制御することが必要である。中間α相の析出を抑制することによって、延性や破壊靭性を確保した上で高強度化が図ることが可能となる。中間α相の面積率は、好ましくは２．５％以下である。中間α相の面積率は、金属組織の倍率３千倍のＦＥ−ＳＥＭによる顕微鏡写真を画像解析することによって求められる。中間α相の面積率を３％以下に制御するには、鍛造工程を所定の条件で行う方法があるが、詳細は後記する。
(Area ratio of intermediate α phase)
According to the study by the present inventors, it has been found that the area ratio of the intermediate α phase is related to ductility, fracture toughness, and strength.
In order to increase the strength while ensuring the ductility and fracture toughness of the titanium alloy forged material, it is necessary to control the area ratio of the intermediate α phase to 3% or less. By suppressing the precipitation of the intermediate α phase, it is possible to increase the strength while ensuring ductility and fracture toughness. The area ratio of the intermediate α phase is preferably 2.5% or less. The area ratio of the intermediate α phase can be determined by image analysis of a microphotograph obtained by FE-SEM with a magnification of 3,000 times of the metal structure. In order to control the area ratio of the intermediate α phase to 3% or less, there is a method in which the forging process is performed under predetermined conditions, but details will be described later.
（一次α相の面積率）
チタン合金鍛造材の破壊靭性を確保しつつ強度を高めるために、一次α相の面積率を２０％以下に制御する。延性を確保する上で一次α相は一定量必要であるが、２０％を超えると破壊靭性や強度が低下する。一次α相の面積率は、好ましくは１５％未満であり、更に好ましくは１０％未満である。一次α相の面積率は、金属組織の倍率４００倍の光学顕微鏡写真を画像解析することによって求められる。一次α相の面積率を２０％以下に制御するには、溶体化工程を所定の条件で行う方法があるが、詳細は後記する。
(Area ratio of primary α phase)
In order to increase the strength while ensuring the fracture toughness of the titanium alloy forged material, the area ratio of the primary α phase is controlled to 20% or less. In order to ensure ductility, a certain amount of the primary α phase is necessary, but when it exceeds 20%, fracture toughness and strength are lowered. The area ratio of the primary α phase is preferably less than 15%, more preferably less than 10%. The area ratio of the primary α phase is obtained by image analysis of an optical micrograph of a metal structure at a magnification of 400 times. In order to control the area ratio of the primary α phase to 20% or less, there is a method in which the solution treatment step is performed under predetermined conditions. Details will be described later.
（一次α相の平均粒径）
チタン合金鍛造材の延性を確保するために、一次α相の平均粒径を２．５μｍ以下に制御する。一次α相の平均粒径が２．５μｍを超えて粗大であると、一次α相に歪みが集中して延性が低下し易いと考えられる。一次α相の平均粒径は、好ましくは２．３μｍ以下である。尚、粒径は、円相当径として求められる。一次α相の平均粒径は、金属組織の倍率４００倍の光学顕微鏡写真を画像解析することによって求められる。一次α相の平均粒径を２．５μｍ以下に制御するには、鍛造工程を所定の条件で行う方法があるが、詳細は後記する。
(Average particle size of primary α phase)
In order to ensure the ductility of the titanium alloy forged material, the average particle size of the primary α phase is controlled to 2.5 μm or less. If the average particle size of the primary α phase exceeds 2.5 μm and is coarse, it is considered that strain concentrates on the primary α phase and the ductility tends to decrease. The average particle diameter of the primary α phase is preferably 2.3 μm or less. In addition, a particle size is calculated | required as a circle equivalent diameter. The average particle diameter of the primary α phase is obtained by image analysis of an optical micrograph of a metal structure at a magnification of 400 times. In order to control the average particle size of the primary α phase to 2.5 μm or less, there is a method in which the forging process is performed under predetermined conditions. Details will be described later.
（二次α相および中間α相の平均間隔）
チタン合金鍛造材の強度を高めるために、二次α相および中間α相の平均間隔を２００ｎｍ以下に制御する。ここで、二次α相および中間α相の平均間隔とは、二次α相相互の間隔、中間α相相互の間隔、および二次α相と中間α相との間の間隔の３種類の間隔を含んでいる。二次α相および中間α相の平均間隔は、より好ましくは１９０ｎｍ以下である。一方、二次α相および中間α相の平均間隔が著しく小さいと、鍛造材が脆化する恐れがあるため、二次α相および中間α相の平均間隔は、１００ｎｍ以上であり、１１０ｎｍ以上がより好ましい。二次α相および中間α相の平均間隔は、金属組織の倍率３万倍のＦＥ−ＳＥＭによる顕微鏡写真を画像解析することによって求められる。二次α相および中間α相の平均間隔を２００ｎｍ以下に制御する方法として、時効工程を所定の条件で行う方法があるが、詳細は後記する。
(Average interval between secondary α phase and intermediate α phase)
In order to increase the strength of the titanium alloy forging, the average interval between the secondary α phase and the intermediate α phase is controlled to 200 nm or less. Here, the average interval between the secondary α phase and the intermediate α phase includes three types of intervals: the interval between the secondary α phases, the interval between the intermediate α phases, and the interval between the secondary α phase and the intermediate α phase. Includes intervals. The average interval between the secondary α phase and the intermediate α phase is more preferably 190 nm or less. On the other hand, if the average interval between the secondary α phase and the intermediate α phase is extremely small, the forged material may be embrittled. Therefore, the average interval between the secondary α phase and the intermediate α phase is 100 nm or more, and 110 nm or more. More preferred. The average space | interval of a secondary alpha phase and an intermediate | middle alpha phase is calculated | required by image-analyzing the microscope picture by FE-SEM of magnification 30,000 times of a metal structure. As a method for controlling the average interval between the secondary α phase and the intermediate α phase to 200 nm or less, there is a method in which the aging step is performed under predetermined conditions, details of which will be described later.
以上のように、本発明のチタン合金鍛造材は、特定の化学組成を有し、その金属組織を一次α相、二次α相および中間α相によって規定される上記の特性を満足する特定の形態とすることによって、延性、破壊靭性および強度をバランスよく満足したものとすることができる。 As described above, the titanium alloy forged material of the present invention has a specific chemical composition and has a specific microstructure satisfying the above-mentioned characteristics defined by the primary α phase, the secondary α phase, and the intermediate α phase. By adopting the form, the ductility, fracture toughness and strength can be satisfied in a well-balanced manner.
〔チタン合金鍛造材の製造方法〕
次に、本発明で規定する組織を得るための製造方法の一例について説明する。
上記の金属組織を有するチタン合金鍛造材は、以下に記載するチタン合金鍛造材の製造方法を適用することによって、製造することが可能である。本発明のチタン合金鍛造材の製造方法は、鍛造工程、溶体化工程、時効工程の各工程において、以下に記載する特定の加工条件で加工を行うことを特徴としている。
[Production method of titanium alloy forging]
Next, an example of the manufacturing method for obtaining the structure | tissue prescribed | regulated by this invention is demonstrated.
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.
（チタン合金）
本発明のニアβ型チタン合金は、元素Ｘの含有量（質量％）を[Ｘ]としたときに、下記式（１）で表されるＭｏ当量［Ｍｏ］ｅｑが１０以上１３未満であるチタン合金からなる。
[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）
(Titanium alloy)
In the near β-type titanium alloy of the present invention, the Mo equivalent [Mo] eq represented by the following formula (1) is 10 or more and less than 13 when the content (mass%) of the element X is [X]. Made of 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)
本発明に係るチタン合金鍛造材は、前記組成のチタン合金からなるインゴットを下記の条件でビレットに鍛造し、溶体化処理、時効処理を行って所望の製品形状に製造される。尚、下記に記載した製造条件以外の製造工程、製造条件については、公知の条件を適宜適用して行うことによって、チタン合金鍛造材を得ることができる。 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.
（鍛造工程）
鍛造工程では、まず、β変態域に加熱して鍛造を行い、鍛造材としての形状を整える。この際、その後の熱処理の工程で生成される一次α相の粗大化や、中間α相の面積率を抑制するために、β鍛造時の加熱温度は１０００℃未満とする。
(Forging process)
In the forging process, first, forging is performed by heating to the β transformation region, and the shape as a forging material is adjusted. At this time, in order to suppress the coarsening of the primary α phase generated in the subsequent heat treatment step and the area ratio of the intermediate α phase, the heating temperature during β forging is set to less than 1000 ° C.
その後、α＋β温度域に加熱して、α＋β域で鍛造する。この際、中間α相の面積率を抑制するため、累積歪量εを２未満へ制御するとともに、鍛造終了温度を４５０℃以上とする。この中間α相は、β母相の回復が進むとより顕著に発生する傾向にあるため、上記の通り、鍛造歪みを抑え、且つ鍛造温度の低下を防ぐことが好ましい。また、α＋β域での保持時間が長いと粗大なα相が増えるため、トータルの累積加熱時間（７００℃以上での保持時間）は９０ｈｒ以下に制御する。 Then, it heats to (alpha) + (beta) temperature range and forges in (alpha) + (beta) area | region. At this time, in order to suppress the area ratio of the intermediate α phase, the cumulative strain amount ε is controlled to be less than 2, and the forging end temperature is set to 450 ° C. or higher. Since this intermediate α phase tends to be more prominent as the recovery of the β matrix progresses, it is preferable to suppress forging distortion and prevent a forging temperature from decreasing as described above. Further, if the holding time in the α + β region is long, the coarse α phase increases, so the total cumulative heating time (holding time at 700 ° C. or higher) is controlled to 90 hours or shorter.
ここで、相当歪量は、相当塑性ひずみ量ともいう。試験片採取位置におけるα＋β域での相当歪量を市販のFEM解析ソフト（例えば、TRANSVALOR社製解析ソフト「FORGE 2011」）を用いて解析することによって測定することができる。累積された相当歪量を「累積歪量ε」と記載する。累積歪量εについても同様に、鍛造を複数回行った際の累積された相当塑性ひずみ量を、市販のFEM解析ソフトを用いて解析することによって測定することができる。 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 2011” manufactured by TRANSVALOR). The accumulated equivalent strain amount is described as “cumulative strain amount ε”. 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.
（溶体化工程）
鍛造後に、溶体化処理を行う。溶体化処理は、（Ｔβ−６０℃）〜（Ｔβ−１０℃）の温度に加熱保持し、保持後に水冷する。（Ｔβ−６０℃）〜（Ｔβ−１０℃）の温度に保持することで、一次α相の面積率を適切に制御することができる。すなわち、一次α相が消失する（０％となる）ことを防ぐために、加熱温度は、（Ｔβ−１０℃）以下とする。一方、一次α相の面積率を２０％以下とするために、加熱温度は、（Ｔβ−６０℃）以上とする。溶体化処理の保持時間は、好ましくは６０〜２４０ｍｉｎである。
(Solution process)
After forging, a solution treatment is performed. In the solution treatment, the solution is heated and held at a temperature of (Tβ-60 ° C.) to (Tβ-10 ° C.), and then cooled with water. By maintaining the temperature at (Tβ-60 ° C.) to (Tβ-10 ° C.), the area ratio of the primary α phase can be appropriately controlled. That is, in order to prevent the primary α phase from disappearing (becomes 0%), the heating temperature is set to (Tβ−10 ° C.) or less. On the other hand, in order to set the area ratio of the primary α phase to 20% or less, the heating temperature is set to (Tβ-60 ° C.) or more. The holding time of the solution treatment is preferably 60 to 240 min.
（時効工程）
溶体化処理後に、時効処理を行う。時効処理は、４８０℃〜５２０℃の温度に保持する。４８０℃〜５２０℃の温度に管理することによって、二次α相および中間α相の平均間隔を適切に制御することができる。時効処理の保持時間は、好ましくは２〜１２ｈｒである。
(Aging process)
An aging treatment is performed after the solution treatment. The aging treatment is maintained at a temperature of 480 ° C to 520 ° C. By managing the temperature between 480 ° C. and 520 ° C., the average interval between the secondary α phase and the intermediate α phase can be appropriately controlled. The holding time of the aging treatment is preferably 2 to 12 hours.
以下に、本発明の効果を確認した実施例を、本発明の要件を満たさない比較例と対比して具体的に説明する。尚、本発明は以下の実施例に限定されるものではない。 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.
〔試験材の作製〕
ＡＭＳ４９８４で規定されるTi-10V-2Fe-3Al合金（Ｔβ：８１０℃、Ｍｏ当量１１．７）からなるビレットを用いて、β変態点以上の温度で鍛造後に、表１に記載の各条件で、仕上げ鍛造、熱処理を行った。表１には、α＋β域での仕上げ鍛造における累積歪量εを示した。
[Production of test materials]
Using a billet made of a Ti-10V-2Fe-3Al alloy (Tβ: 810 ° C., Mo equivalent 11.7) defined by AMS 4984, after forging at a temperature equal to or higher than the β transformation point, each condition described in Table 1 Finished forging and heat treatment were performed. Table 1 shows the cumulative strain amount ε in finish forging in the α + β region.
鍛造後の素材を使って、溶体化処理および時効処理を表１に記載の条件で行った。溶体化の加熱保持後は、水冷した。時効処理は、所定温度に加熱保持後、空冷にて室温まで冷却した。溶体化処理や時効処理の時間は、表１に記載の加熱温度の炉に入れてからの時間とした。 Using the forged material, solution treatment and aging treatment were performed under the conditions shown in Table 1. The solution was cooled with water after heating. In the aging treatment, after heating and holding at a predetermined temperature, it was cooled to room temperature by air cooling. The time for the solution treatment and the aging treatment was the time after being placed in the furnace at the heating temperature shown in Table 1.
〔試験材の評価〕
得られた鍛造材からそれぞれ評価用試験片を切り出して評価に供した。このとき、物性がばらつく端部を避けるため、引張試験用試験片と組織観察用ブロックを切り出す位置は、鍛造材の長さ方向（Ｌ方向、鍛伸方向）の各端部から５０ｍｍ以上内側となる位置で切り出した。さらに、前記範囲内の鍛造材の任意の位置において、鍛造材の幅方向および厚さ方向における断面平面が得られるように、長さ方向と直角方向であって、厚さ方向と平行に切断した。得られた断面において最大内接円が得られる位置で最大内接円を描いた。その最大内接円において３０ｍｍ±１０ｍｍの深さとなる位置が、試験片の中心位置となるように試験片を採取した。
得られた試験材（試験材Ｎｏ.１〜６）について、以下に記載する評価条件によって、各種物性を測定・評価した。評価結果は表２に示した。
尚、試験材Ｎｏ.１〜６はいずれも、ニアβ型チタン合金鍛造材であり、α相とβ相の面積率の合計が９９％以上であった。
[Evaluation of test material]
Test pieces for evaluation were cut out from the obtained forged materials and used for evaluation. At this time, in order to avoid the end portion where the physical properties vary, the position where the tensile test specimen and the structure observation block are cut out is 50 mm or more inside from each end portion in the length direction (L direction, forging direction) of the forging. It cut out at the position. Further, at any position of the forging within the above range, the forging was cut in a direction perpendicular to the length direction and parallel to the thickness direction so as to obtain a cross-sectional plane in the width direction and the thickness direction of the forging. . The maximum inscribed circle was drawn at a position where the maximum inscribed circle was obtained in the obtained cross section. The test piece was sampled so that the position where the depth of 30 mm ± 10 mm in the maximum inscribed circle would be the center position of the test piece.
About the obtained test material (test material No. 1-6), various physical properties were measured and evaluated by the evaluation conditions described below. The evaluation results are shown in Table 2.
Note that all of the test materials No. 1 to 6 were forged near β-type titanium alloys, and the total area ratio of the α phase and the β phase was 99% or more.
（引張試験）
試験材の長さ方向と引張試験片の荷重軸方向が平行になるように、各試験材毎に２個ずつ試験片を採取した。引張試験ではＡＳＴＭ規格のＥ８に準拠して実施した。試験片サイズはＡＳＴＭ規格のＥ８のSpecimen2とした。測定の結果、強度（引張強さ、ＴＳ）は１２５０ＭＰａ以上、延性（伸び、ＥＬ）は８％以上のとき、合格と判定した。
(Tensile test)
Two test pieces were collected for each test material so that the length direction of the test material and the load axis direction of the tensile test piece were parallel. The tensile test was performed in accordance with ASTM standard E8. The specimen size was ASTM standard E8 Specimen2. As a result of the measurement, when the strength (tensile strength, TS) was 1250 MPa or more and the ductility (elongation, EL) was 8% or more, it was determined to be acceptable.
（破壊靭性試験（ＫＩＣ））
ＡＳＴＭのＥ３９９に準拠して実施した。試験片はＳ−Ｌ方向の向きに各試験材毎に２個ずつ採取し、試験片の厚みは１９ｍｍとした。得られた結果は、破壊靱性値ＫＩＣ（ＭＰａ・ｍ１／２）として算出した。ＫＩＣが４０以上のとき合格と判定した。
(Fracture toughness test (KIC))
The test was conducted in accordance with ASTM E399. Two test pieces were sampled for each test material 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 40 or more, it was determined to be acceptable.
（組織観察）
＜試料調製＞
鍛造材のＬ方向（光学顕微鏡で観察した際にβ結晶粒の伸張方向で判別できる）に平行な断面が観察できるように、引張試験片採取位置のすぐ隣の深さが同等の位置から、各試験材毎に２試験片ずつ組織観察用のブロックを切出した。
樹脂包埋、研磨および腐食（フッ硝酸溶液）を実施し組織観察用のサンプルとし、光学顕微鏡（OLYMPUS社製、GX71）観察、ＦＥ−ＳＥＭ（日立製作所社製、SU-70））観察を実施した。
(Tissue observation)
<Sample preparation>
From the position where the depth immediately next to the tensile specimen collection position is the same so that a cross section parallel to the L direction of the forged material (which can be discriminated by the β crystal grain extension direction when observed with an optical microscope) can be observed. Two test pieces for each specimen were cut out for observing the structure.
Resin embedding, polishing, and corrosion (fluoric nitric acid solution) were performed to obtain a sample for tissue observation, observation with an optical microscope (OLYMPUS, GX71), FE-SEM (Hitachi, SU-70)) did.
＜一次α相の粒径、面積率の測定＞
各試験材の各試験片毎に、倍率４００倍の光学顕微鏡により観察した。粒径が０．５μｍ以上と判別された領域を「一次α相」とし、一次α相以外の領域は「一次α相以外の相」とした。各試験片において、各５枚の写真をランダムに取得し、各写真毎に一次α相と判別された領域の個々の面積から、一次α相の平均粒径（＝円相当径）および面積率（個々の面積の合計の比率）を画像解析（画像解析ソフトウェア；日本ローパー社製、Image-Pro Plus、ver.7.0）により求めた。
<Measurement of primary α phase particle size and area ratio>
Each test piece of each test material was observed with an optical microscope having a magnification of 400 times. The region where the particle size was determined to be 0.5 μm or more was designated as “primary α phase”, and the region other than the primary α phase was designated as “phase other than primary α phase”. For each test piece, five photographs were randomly obtained, and the average particle diameter (= equivalent circle diameter) and area ratio of the primary α phase were determined from the individual areas of the regions identified as the primary α phase for each photo. (Total ratio of individual areas) was determined by image analysis (image analysis software; manufactured by Nippon Roper, Image-Pro Plus, ver. 7.0).
尚、一次α相は鍛造や熱処理によって徐々にくびれ（凹み）が生じ、更には分断されていくが、くびれが生じていても互いに重なっている一次α相については一つの一次α相としてカウントした。 The primary α phase gradually narrows (dents) due to forging or heat treatment, and is further divided. However, even if constriction occurs, the primary α phases that overlap each other are counted as one primary α phase. .
解析結果から、一次α相の平均粒径（各試験材毎に２試験片×５枚の写真の平均）、平均面積率（各試験材毎に２試験片×５枚の写真の平均）を算出した。 From the analysis results, the average particle size of the primary α phase (average of 2 test pieces x 5 photos for each test material) and average area ratio (average of 2 test pieces x 5 photos for each test material) Calculated.
＜中間α相の面積率の測定＞
各試験材の各試験片毎に、倍率３千倍のＦＥ−ＳＥＭにより観察を行い、各試験片において、各５枚の写真をランダムに撮影した。各写真毎に画像解析によって、長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相（中間α相）を特定した。
<Measurement of area ratio of intermediate α phase>
Each test piece of each test material was observed with an FE-SEM at a magnification of 3,000 times, and five photographs were taken at random for each test piece. An α phase (intermediate α phase) having a major axis of 2 μm or more, a minor axis of 0.1 μm or more and less than 0.5 μm was identified by image analysis for each photograph.
ここで、短径とは、画像解析ソフトの測定項目：「直径（最小）」により求めた。すなわち「α相の領域の重心を通り、かつα相の領域の外周の２点を結ぶ径のうちで最小のもの」を短径とした。なお、まれに、重心がα相の領域の外の場合があるが、その場合は、重心を中心にしてα相の領域に接する最小の円が接する点を定め、重心と接点を結ぶ直線がα相の領域を横切った長さをもって、短径とした。但し、横切る線分が複数存在する場合は、重心から最も近い線分を短径とした。 Here, the minor axis was obtained from the measurement item of the image analysis software: “diameter (minimum)”. That is, “the smallest diameter among the diameters passing through the center of gravity of the α-phase region and connecting two points on the outer periphery of the α-phase region” was defined as the minor axis. In rare cases, the center of gravity may be outside the α-phase region. In this case, the point where the smallest circle in contact with the α-phase region touches the center of gravity is defined, and a straight line connecting the center of gravity and the contact point is formed. The length across the α phase region was taken as the minor axis. However, when there are a plurality of crossing line segments, the line segment closest to the center of gravity is defined as the minor axis.
また、長径については、α相の領域内で取りうる最大の線分により求めた。長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相の各領域について、それぞれの面積を求めた。そして、それらの面積の合計をもって「長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相（中間α相）の面積率」とした。
解析結果から、中間α相の平均面積率（各試験材毎に２試験片×５枚の写真の平均）を算出した。
Further, the major axis was obtained from the maximum line segment that can be taken in the region of the α phase. The area of each α phase region having a major axis of 2 μm or more, a minor axis of 0.1 μm or more and less than 0.5 μm was determined. The total of these areas was defined as “the area ratio of the α phase (intermediate α phase) having a major axis of 2 μm or more, a minor axis of 0.1 μm or more and less than 0.5 μm”.
From the analysis results, the average area ratio of the intermediate α phase (average of 2 test pieces × 5 photographs for each test material) was calculated.
＜二次α相および中間α相の平均間隔の測定＞
各試験材の各試験片毎に、倍率３万倍のＦＥ−ＳＥＭにより観察を行い、一次α相以外の相から各５枚の写真をランダムに撮影した。
写真を元に、二次α相を例に取って測定方法を以下に説明する。水平方向及び垂直方向に写真の端から端まで線分を各５本、等間隔に引き、線分が二次α相と交わる点をカウントした。その後、（線分長さの合算）÷（カウント数の総数）から、二次α相の平均間隔を算出した。図１に二次α相の平均間隔を算出する方法を示す模式図を示した。線分ｌと二次α相Ｐとの交点Ｘ１〜Ｘ５をカウントした。
尚、測定の際、まれに極端に微細なα相や極端に微細なβ相の領域が存在する場合があるが、画像解析ソフトにて円相当径が５ｎｍ以上とカウントされるα相・β相をカウント対象とした。ここで、円相当径の算出にあたっては、図１の交点Ｘ４、Ｘ５を通る二次α相のような場合、二次α相の中に含まれるβ相（白色）の領域は円相当径を算出する際の計算対象としていない（つまり黒色の領域のみの面積から円相当径を求めた。）
ここで、二次α相および中間α相の平均間隔の測定においては、二次α相の領域が大部分を占めるが、二次α相および中間α相の両者を含めた平均間隔として求めた。
解析結果から、二次α相および中間α相の平均間隔（各試験材毎に２試験片×５枚の写真の平均）を算出した。
<Measurement of average interval between secondary α phase and intermediate α phase>
Each test piece of each test material was observed with an FE-SEM at a magnification of 30,000, and five photographs were randomly taken from phases other than the primary α phase.
The measurement method will be described below based on the photograph and taking the secondary α phase as an example. Five line segments were drawn at equal intervals in the horizontal and vertical directions from end to end of the photograph, 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 rare cases, there may be an extremely fine α phase or extremely fine β phase region at the time of measurement, but the equivalent phase 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)
Here, in the measurement of the average interval between the secondary α phase and the intermediate α phase, the region of the secondary α phase occupies most, but was determined as the average interval including both the secondary α phase and the intermediate α phase. .
From the analysis results, the average interval between the secondary α phase and the intermediate α phase (average of 2 test pieces × 5 photographs for each test material) was calculated.
試験材Ｎｏ．３〜５は、いずれも本発明のＭｏ当量を満足し、前記の特定の製造条件を用いて製造されたものである。試験材Ｎｏ．３〜５は、一次α相の面積率、一次α相の平均粒径および中間α相の面積率において、本発明の規定を満足するものである。そのため、いずれの試験材も、延性と破壊靭性に優れ、強度においても優れたものであった。 Test material No. Nos. 3 to 5 all satisfy the Mo equivalent of the present invention and are manufactured using the specific manufacturing conditions described above. Test material No. 3 to 5 satisfy the definition of the present invention in the area ratio of the primary α phase, the average particle diameter of the primary α phase, and the area ratio of the intermediate α phase. Therefore, all the test materials were excellent in ductility and fracture toughness and in strength.
試験材Ｎｏ．１は、α＋β域鍛造工程における累積歪量εが大きいため、中間α相の面積率が３％を超えており、破壊靭性と強度において劣るものであった。
試験材Ｎｏ．２は、β鍛造の温度がやや高く、α＋β域鍛造における鍛造終了温度が好ましい温度に比べて低いため、一次α相の平均粒径が２．５μｍを超え、中間α相の面積率が３％を超えており、破壊靭性、延性および強度において劣るものであった。
試験材Ｎｏ．６は、β鍛造の温度がやや高く、α＋β域鍛造における累積加熱時間が９０ｈｒを超えているため、一次α相の平均粒径が２．５μｍを超えており、延性において劣るものであった。
Test material No. No. 1 had a large cumulative strain amount ε in the α + β region forging process, so that the area ratio of the intermediate α phase exceeded 3%, and the fracture toughness and strength were inferior.
Test material No. No. 2 has a slightly higher β forging temperature and a lower forging end temperature in α + β region forging than the preferred temperature, so that the average particle size of the primary α phase exceeds 2.5 μm and the area ratio of the intermediate α phase is 3%. The fracture toughness, ductility and strength were inferior.
Test material No. No. 6 was slightly inferior in ductility because the temperature of β forging was slightly high and the cumulative heating time in α + β region forging exceeded 90 hr, so the average particle size of the primary α phase exceeded 2.5 μm.
Ｐ 二次α相
Ｘ１、Ｘ２、Ｘ３、Ｘ４、Ｘ５ 交点
ｌ 線分
P Secondary α phase X1, X2, X3, X4, X5 Intersection l Line segment
Claims (1)
[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）
α相とβ相の面積率の合計が９９％以上であり、
一次α相の面積率が２０％以下であり、
一次α相の平均粒径が２．５μｍ以下であり、
長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相の面積率が３％以下であり、
二次α相および前記長径２μｍ以上、短径０．１μｍ以上かつ０．５μｍ未満のα相の平均間隔が１００〜２００ｎｍであることを特徴とするチタン合金鍛造材。 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 of 10 or more and less than 13 represented by the following formula (1). 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 total area ratio of α phase and β phase is 99% or more,
The area ratio of the primary α phase is 20% or less,
The average particle size of the primary α phase is 2.5 μm or less,
The area ratio of the α phase having a major axis of 2 μm or more, a minor axis of 0.1 μm or more and less than 0.5 μm is 3% or less,
The titanium alloy forging material, wherein an average interval between the secondary α phase and the α phase having a major axis of 2 μm or more, a minor axis of 0.1 μm or more and less than 0.5 μm is 100 to 200 nm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2016116350A JP2017218661A (en) | 2016-06-10 | 2016-06-10 | Titanium alloy forging material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2016116350A JP2017218661A (en) | 2016-06-10 | 2016-06-10 | Titanium alloy forging material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2017218661A true JP2017218661A (en) | 2017-12-14 |
Family
ID=60658821
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2016116350A Pending JP2017218661A (en) | 2016-06-10 | 2016-06-10 | Titanium alloy forging material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2017218661A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020045536A (en) * | 2018-09-20 | 2020-03-26 | Ntn株式会社 | Machine component |
| CN112642976A (en) * | 2020-12-01 | 2021-04-13 | 太原理工大学 | Two-stage non-isothermal forging method for controlling titanium alloy beta forging texture |
| CN112974700A (en) * | 2021-02-19 | 2021-06-18 | 西北工业大学 | Forming method for realizing grain refining of near-beta type titanium alloy thin-wall structural member structure |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62267438A (en) * | 1986-05-13 | 1987-11-20 | Mitsubishi Metal Corp | High-strength ti alloy material excellent in workability and its production |
| JPH03240939A (en) * | 1990-02-19 | 1991-10-28 | Sumitomo Metal Ind Ltd | Manufacture of high ductility and high toughness titanium alloy |
| JPH07150316A (en) * | 1993-12-01 | 1995-06-13 | Nkk Corp | Manufacture of (alpha+beta) type ti alloy forged material |
| JPH07252617A (en) * | 1994-03-11 | 1995-10-03 | Sumitomo Metal Ind Ltd | Production of titanium alloy having high strength and high toughness |
| JPH08158028A (en) * | 1994-12-07 | 1996-06-18 | Sumitomo Metal Ind Ltd | Toughening of titanium alloy |
| JP2012528932A (en) * | 2009-05-29 | 2012-11-15 | テイタニウム メタルス コーポレイシヨン | High-strength near β-type titanium alloy and method for producing the same |
| WO2016084980A1 (en) * | 2014-11-28 | 2016-06-02 | 新日鐵住金株式会社 | Titanium alloy member and method of manufacturing titanium alloy member |
| JP2017002390A (en) * | 2015-06-16 | 2017-01-05 | 株式会社神戸製鋼所 | Titanium alloy forging material |
-
2016
- 2016-06-10 JP JP2016116350A patent/JP2017218661A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62267438A (en) * | 1986-05-13 | 1987-11-20 | Mitsubishi Metal Corp | High-strength ti alloy material excellent in workability and its production |
| JPH03240939A (en) * | 1990-02-19 | 1991-10-28 | Sumitomo Metal Ind Ltd | Manufacture of high ductility and high toughness titanium alloy |
| JPH07150316A (en) * | 1993-12-01 | 1995-06-13 | Nkk Corp | Manufacture of (alpha+beta) type ti alloy forged material |
| JPH07252617A (en) * | 1994-03-11 | 1995-10-03 | Sumitomo Metal Ind Ltd | Production of titanium alloy having high strength and high toughness |
| JPH08158028A (en) * | 1994-12-07 | 1996-06-18 | Sumitomo Metal Ind Ltd | Toughening of titanium alloy |
| JP2012528932A (en) * | 2009-05-29 | 2012-11-15 | テイタニウム メタルス コーポレイシヨン | High-strength near β-type titanium alloy and method for producing the same |
| WO2016084980A1 (en) * | 2014-11-28 | 2016-06-02 | 新日鐵住金株式会社 | Titanium alloy member and method of manufacturing titanium alloy member |
| JP2017002390A (en) * | 2015-06-16 | 2017-01-05 | 株式会社神戸製鋼所 | Titanium alloy forging material |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020045536A (en) * | 2018-09-20 | 2020-03-26 | Ntn株式会社 | Machine component |
| JP7154083B2 (en) | 2018-09-20 | 2022-10-17 | Ntn株式会社 | machine parts |
| CN112642976A (en) * | 2020-12-01 | 2021-04-13 | 太原理工大学 | Two-stage non-isothermal forging method for controlling titanium alloy beta forging texture |
| CN112974700A (en) * | 2021-02-19 | 2021-06-18 | 西北工业大学 | Forming method for realizing grain refining of near-beta type titanium alloy thin-wall structural member structure |
| CN112974700B (en) * | 2021-02-19 | 2022-07-26 | 西北工业大学 | Forming method for realizing grain refining of near-beta type titanium alloy thin-wall structural member structure |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP7024861B2 (en) | Titanium alloy wire rod and titanium alloy wire rod manufacturing method | |
| US12000021B2 (en) | α+β type titanium alloy wire and manufacturing method of α+β type titanium alloy wire | |
| JP6889418B2 (en) | Manufacturing method of Ni-based super heat-resistant alloy and Ni-based super heat-resistant alloy | |
| JP4493029B2 (en) | Α-β type titanium alloy with excellent machinability and hot workability | |
| JP5592818B2 (en) | Α-β type titanium alloy extruded material excellent in fatigue strength and method for producing the α-β type titanium alloy extruded material | |
| JP6823827B2 (en) | Heat-resistant Ti alloy and its manufacturing method | |
| JP6705508B2 (en) | NiCrFe alloy | |
| JP5885169B2 (en) | Ti-Mo alloy and manufacturing method thereof | |
| WO2014042160A1 (en) | Cu-al-mn based alloy material exhibiting stable superelasticity and manufacturing process therefor | |
| WO2015008689A1 (en) | Expanded member comprising cu-al-mn alloy material and exhibiting superior anti-stress corrosion properties, and use therefor | |
| KR20130134014A (en) | Beta type titanium alloy with low elastic modulus and high strength | |
| WO2018193810A1 (en) | High strength and low thermal expansion alloy wire | |
| JP6315319B2 (en) | Method for producing Fe-Ni base superalloy | |
| JP5477519B1 (en) | Resource-saving titanium alloy member excellent in strength and toughness and manufacturing method thereof | |
| JP6696202B2 (en) | α + β type titanium alloy member and manufacturing method thereof | |
| JP2022037155A (en) | High temperature titanium alloys | |
| JP2017218661A (en) | Titanium alloy forging material | |
| JP6269836B2 (en) | Titanium alloy member having shape change characteristic in the same direction as the machining direction | |
| JP2019112686A (en) | Ni-BASED HEAT RESISTANT ALLOY | |
| JP2017036477A (en) | Austenitic heat resistant alloy member and manufacturing method therefor | |
| Siahboumi et al. | Effect of hafnium addition on microstructure and room temperature mechanical properties of the Ti-48Al-2Cr-2Nb intermetallic alloy | |
| JP6851147B2 (en) | Titanium alloy forged material | |
| JP2017002390A (en) | Titanium alloy forging material | |
| JP6432328B2 (en) | High strength titanium plate and manufacturing method thereof | |
| JP2017179478A (en) | Austenitic heat resistant alloy member and manufacturing method therefor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20190530 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20200124 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20200218 |
|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20200811 |