JPS6310216B2

JPS6310216B2 -

Info

Publication number: JPS6310216B2
Application number: JP15519785A
Authority: JP
Inventors: Hidehiro Onodera; Toshihiro Yamagata; Michio Yamazaki
Original assignee: KAGAKU GIJUTSUCHO KINZOKU ZAIRYO GIJUTSU KENKYU SHOCHO
Current assignee: KAGAKU GIJUTSUCHO KINZOKU ZAIRYO GIJUTSU KENKYU SHOCHO
Priority date: 1985-07-16
Filing date: 1985-07-16
Publication date: 1988-03-04
Also published as: JPS6217145A

Description

[Detailed description of the invention]

産業上の利用分野本発明は超塑性特性と高温比強度及び延性に優
れた超塑性加工に適した高強度耐熱チタン合金に
関する。従来、Ti合金部品は鍛造または切削加工によ
り製造されてきたが、コンプレツサーローターの
場合には、切削くずが約90％にもなり極めて歩留
りが悪いばかりでなく、作業性も悪い。これを改
善するためには合金の超塑性加工が有利な手段で
ある。超塑性特性は加工温度でα相とβ相の体積比が
１：１に近いTi合金が優れている。また超塑性
加工温度は800〜900℃の温度が適している。900
℃より高温では結晶粒の粗大化及び酸化が生じ易
くなるため、超塑性特性が劣化する。また800℃
より低温では変形応力が高くなるため、超塑性加
工が困難となる。従来技術従来、超塑性加工に適した合金としては、Ti
−6Al−4V合金、Ti−6Al−2Sn−4Zr−2Mo合
金、Ti−6Al−2Sn−4Zr−6Mo合金等が知られ
ている。しかし、これらのチタン合金はいずれも
β型Ti合金と比べて強度が低い欠点があつた。発明の目的本発明は従来の超塑性加工に適したチタン合金
の欠点を改善せんとするものであり、その目的は
超塑性特性が優れ、かつ高温比強度及び延性の優
れた高強度耐熱チタン合金を提供するにある。発明の構成本発明者は前記目的を達成すべく鋭意研究の結
果、ある特定範囲の組成において、800℃におけ
るα相の量が30〜70％になるよう調整すると、超
塑性特性が優れると同時に高温比強度及び延性の
優れた高強度耐熱性チタン合金が得られることを
究明し得た。この知見に基いて本発明を完成し
た。本発明の要旨は、重量％で、Al5.4〜6.6％、
V1.3〜3.1％、Sn0.7〜1.1％、Zr0.7〜5.3％、
Mo2.2〜2.6％、Cr2.4〜3.7％、Fe1.4〜2.8％、
O0.10〜0.16％を含み、残部が実質的にTiよりな
るチタン合金であり、かつ800℃におけるα相の
体積率が30〜70％であることを特徴とする超塑性
加工に適した高強度耐熱チタン合金にある。本発明のチタン合金において、Alは主として
α相に固溶してα相を強化する作用をする。しか
し、Al量が5.4％（％は重量％、以下同じ）未満
であるとα相強化の効果が十分でなく、また6.6
％を超えるとα相量が増加して十分な超塑性特性
が得られなくなるので、Alは5.4〜6.6％の範囲で
あることが必要である。Ｖはα相及びβ相に固溶して、これらの相を強
化する作用をする。しかし、Ｖ量が1.3％未満で
あると強化効果が十分得られなく、また3.1％を
超えるとα相量が減少して十分な超塑性特性が得
られなくなるので、Ｖは1.3〜3.1％の範囲である
ことが必要である。 Sn及びZrはα相及びβ相にほぼ同じ比率で固
溶して、これらの相を強化する作用をする。しかし、Sn量が0.7％未満であると強化効果が
十分得られなく、また1.1％を超えると、比重が
大きくなり、比強度が低下する。また、Zr量が0.7％未満では強化効果が得られ
なく、また、5.3％を超えるとα相量が減少して
十分な超塑性特性が得られなくなる。従つて、
Snは0.7〜1.1％、Zrは0.7〜5.3％の範囲であるこ
とが必要である。 Mo、Cr及びFeは主としてβ相に固溶してβ相
を強化する作用をする。しかし、Mo量が2.2％未
満であると十分な強化効果が得られなく、また
2.6％を超えると比重が大きくなるため比強度が
低下するのでMo量は2.2〜2.6％の範囲であるこ
とが必要である。Cr量が2.4％未満であると十分
な強化効果が得られなくなり、また3.7％を超え
るとα相量が減少して十分な超塑性特性が得られ
なくなるので、Cr量は2.4〜3.7％の範囲であるこ
とが必要である。 Fe量が1.4％未満であると、十分な強化効果が
得られなく、また2.8％を超えるとα相が減少し
て十分な超塑性特性が得られなくなるので、Fe
量は1.4〜2.8％の範囲であることが必要である。Ｏは主としてα相に固溶してα相を強化する作
用をする。しかし、Ｏ量が0.10％未満では強化作
用が十分得られなく、また0.16％を超えるとα相
量が増加して十分な超塑性特性が得られなくなる
ので、Ｏ量は0.10〜0.16％の範囲であることが必
要である。本発明のチタン合金の組成各元素の割合は前記
の通りであるが、この範囲内で、更に800℃でα
相を30〜70％含み残部はβ相であることが必要で
ある。それはα相とβ相は互に結晶粒の成長を妨
げ、超塑性特性を向上させるからである。α相が
30％より少ないとβ相の結晶粒が粗大化し易くな
り超塑性特性が劣化する。またα相が70％を超え
ると、α相の結晶粒子が粗大化し易くなり超塑性
特性が劣化する。 α相とβ相の割合が前記割合にする好ましい各
元素の範囲としては、次の割合が挙げられる。 (1) 重量％で、Al6.0〜6.6％、V2.7〜3.1％、
Sn0.7〜1.1％、Zr0.9〜1.3％、Mo2.2〜2.6％、
Cr2.4〜2.8％、Fe1.4〜1.8％、O0.10〜0.15％を
含み、残部は実質的にTiよりなる合金。 (2) 重量％で、Al5.4〜6.0％、V1.3〜1.7％、
Sn0.7〜1.1％、Zr4.9〜5.3％、Mo2.2〜2.6％、
Cr3.3〜3.7％、Fe2.4〜2.8％、O0.12〜0.16％を
含み、残部は実質的にTiよりなる合金。例えばZr量を多くすると、Ｖ量及びAl量を少
なくする必要がある。実施例本発明の下記表１に示す組成の合金と比較のた
めの既存合金を、アーク溶解、鍛造後、800℃で
約85％の熱間圧延を行い、５mmφ引張試験片及び
超塑性試験片を作製して、各々の試験を行つた。
その結果は表２及び表３に示す通りであつた。なお、高温引張試験片は、750〜800℃で１時間
熱処理した後水冷し、再び550〜600℃で４時間熱
処理した後空冷して試験に供した。高温引張試験
は300℃で３×10^-4S^-1の歪速度で行つた。また、超塑性試験片は、熱間圧延のままの状態
で試験に供した。この試験は800℃で、アルゴン
雰囲気中で6.7×10^-4S^-1の歪速度で行つた。 INDUSTRIAL APPLICATION FIELD The present invention relates to a high-strength, heat-resistant titanium alloy that is suitable for superplastic working and has excellent superplastic properties, high-temperature specific strength, and ductility. Conventionally, Ti alloy parts have been manufactured by forging or cutting, but in the case of compressor rotors, cutting waste accounts for approximately 90%, resulting in extremely poor yields and poor workability. In order to improve this, superplastic working of alloys is an advantageous means. Ti alloys with excellent superplastic properties have a volume ratio of α phase to β phase close to 1:1 at the processing temperature. In addition, a temperature of 800 to 900°C is suitable for superplastic processing. 900
At temperatures higher than °C, coarsening and oxidation of crystal grains tend to occur, resulting in deterioration of superplastic properties. Also 800℃
At lower temperatures, the deformation stress increases, making superplastic processing difficult. Conventional technology Conventionally, Ti has been used as an alloy suitable for superplastic processing.
-6Al-4V alloy, Ti-6Al-2Sn-4Zr-2Mo alloy, Ti-6Al-2Sn-4Zr-6Mo alloy, etc. are known. However, all of these titanium alloys had the drawback of lower strength than β-type Ti alloys. Purpose of the Invention The present invention aims to improve the drawbacks of conventional titanium alloys suitable for superplastic working, and its purpose is to develop a high-strength, heat-resistant titanium alloy that has excellent superplastic properties, high-temperature specific strength, and ductility. is to provide. Composition of the Invention As a result of intensive research to achieve the above object, the present inventor found that in a certain specific range of composition, when the amount of α phase at 800°C is adjusted to 30 to 70%, superplastic properties are excellent and at the same time It has been found that a high-strength, heat-resistant titanium alloy with excellent high-temperature specific strength and ductility can be obtained. The present invention was completed based on this knowledge. The gist of the present invention is that in weight%, Al5.4-6.6%,
V1.3~3.1%, Sn0.7~1.1%, Zr0.7~5.3%,
Mo2.2~2.6%, Cr2.4~3.7%, Fe1.4~2.8%,
It is a titanium alloy that contains 0.10 to 0.16% O and the remainder is substantially Ti, and has a volume fraction of α phase of 30 to 70% at 800℃. Made of strength and heat-resistant titanium alloy. In the titanium alloy of the present invention, Al mainly acts as a solid solution in the α phase to strengthen the α phase. However, if the Al amount is less than 5.4% (% is weight%, the same applies hereinafter), the effect of α phase strengthening will not be sufficient, and 6.6
If it exceeds 5.4% to 6.6%, the amount of α phase increases and sufficient superplastic properties cannot be obtained, so Al needs to be in the range of 5.4 to 6.6%. V forms a solid solution in the α phase and β phase and acts to strengthen these phases. However, if the V content is less than 1.3%, a sufficient strengthening effect cannot be obtained, and if it exceeds 3.1%, the α phase content decreases and sufficient superplastic properties cannot be obtained. Must be within the range. Sn and Zr form a solid solution in the α phase and the β phase at approximately the same ratio and act to strengthen these phases. However, if the Sn amount is less than 0.7%, a sufficient reinforcing effect cannot be obtained, and if it exceeds 1.1%, the specific gravity increases and the specific strength decreases. Further, if the Zr content is less than 0.7%, no reinforcing effect can be obtained, and if it exceeds 5.3%, the α phase content decreases and sufficient superplastic properties cannot be obtained. Therefore,
Sn needs to be in the range of 0.7 to 1.1%, and Zr needs to be in the range of 0.7 to 5.3%. Mo, Cr, and Fe mainly act as solid solutions in the β phase to strengthen the β phase. However, if the amount of Mo is less than 2.2%, sufficient strengthening effect cannot be obtained, and
If it exceeds 2.6%, the specific gravity increases and the specific strength decreases, so the amount of Mo needs to be in the range of 2.2 to 2.6%. If the Cr content is less than 2.4%, a sufficient strengthening effect cannot be obtained, and if it exceeds 3.7%, the α phase content decreases and sufficient superplastic properties cannot be obtained. Must be within the range. If the amount of Fe is less than 1.4%, a sufficient strengthening effect cannot be obtained, and if it exceeds 2.8%, the α phase decreases and sufficient superplastic properties cannot be obtained.
The amount should be in the range 1.4-2.8%. O mainly acts as a solid solution in the α phase to strengthen the α phase. However, if the O content is less than 0.10%, a sufficient strengthening effect cannot be obtained, and if it exceeds 0.16%, the α phase content increases and sufficient superplastic properties cannot be obtained, so the O content should be in the range of 0.10 to 0.16%. It is necessary that The composition of the titanium alloy of the present invention The proportions of each element are as described above, but within this range, α
It is necessary to contain 30 to 70% of the phase, with the remainder being β phase. This is because the α phase and β phase mutually inhibit grain growth and improve superplastic properties. α phase
If it is less than 30%, the crystal grains of the β phase tend to become coarser and the superplastic properties deteriorate. Moreover, if the α phase exceeds 70%, the crystal grains of the α phase tend to become coarse, and the superplastic properties deteriorate. Preferred ranges of each element to achieve the above ratio of α phase and β phase include the following ratios. (1) In weight%, Al6.0~6.6%, V2.7~3.1%,
Sn0.7~1.1%, Zr0.9~1.3%, Mo2.2~2.6%,
An alloy containing 2.4 to 2.8% Cr, 1.4 to 1.8% Fe, and 0.10 to 0.15% O, with the balance essentially consisting of Ti. (2) In weight%, Al5.4~6.0%, V1.3~1.7%,
Sn0.7~1.1%, Zr4.9~5.3%, Mo2.2~2.6%,
An alloy containing 3.3 to 3.7% Cr, 2.4 to 2.8% Fe, and 0.12 to 0.16% O, with the remainder essentially consisting of Ti. For example, when increasing the amount of Zr, it is necessary to decrease the amount of V and the amount of Al. Example An alloy of the present invention having the composition shown in Table 1 below and an existing alloy for comparison were arc melted, forged, and then hot rolled at 800°C to approximately 85% to produce a 5 mmφ tensile test piece and a superplastic test piece. were prepared and each test was conducted.
The results were as shown in Tables 2 and 3. The high-temperature tensile test piece was heat-treated at 750-800°C for 1 hour, cooled with water, heat-treated again at 550-600°C for 4 hours, and then air-cooled for testing. High temperature tensile tests were conducted at 300° C. and a strain rate of 3×10 ⁻⁴ S ⁻¹ . In addition, the superplastic test piece was subjected to the test in the hot-rolled state. The test was conducted at 800° C. and a strain rate of 6.7×10 ⁻⁴ S ⁻¹ in an argon atmosphere.

【表】【table】

【表】この試験結果が示すように、本発明のTi合金
は、既存のTi−6Al−4V、Ti−6Al−2Sn−4Zr
−2Mo及びTi−6Al−2Sn−4Zr−6Mo合金に比
べて、延性及び比強度において著しく優れてい
る。すなわち、本発明Ti合金では、比強度が28.7
〜29.7Kgｆ／mm²／ｇ／cm³の値を示す条件で、12.1
〜13.5％の伸びが確保されているのに対して、Ti
−6Al−4V及びTi−6Al−2Sn−4Zr−2Mo合金
では、このような高比強度は得られない。また、Ti−6Al−2Sn−4Zr−6Mo合金の場合
は、比強度が29.9Kgｆ／mm²／ｇ／cm³まで増大する
と、伸びは5.2％まで低下する。また、本発明のTi合金は、410〜680％の超塑
性伸びを有し、最大変形応力も2.9〜3.3Kgｆ／mm²
と十分低いので、超塑性加工に適した合金であ
る。この特性は既存のTi−6Al−2Sn−4Zr−
6Mo合金に比べて著しく優れている。発明の効果本発明のTi合金は、超塑性加工が可能であり、
かつ高温比強度及び延性に優れた特性を有する。
従つて、超塑性加工を適用することにより、切削
加工なしに、しかも優れた特性を持つ例えばコン
プレツサーローター等の部品を安価に、容易に製
造することができる。また、これを使用すること
により、ジエツトエンジンや発電設備などの各種
ガスタービンの軽量化及び高効率化が可能になる
等の優れた効果が得られる。[Table] As this test result shows, the Ti alloy of the present invention
-2Mo and Ti-6Al-2Sn-4Zr-6Mo alloys are significantly superior in ductility and specific strength. In other words, the Ti alloy of the present invention has a specific strength of 28.7.
12.1 under conditions showing a value of ~29.7Kgf/mm ² /g/cm ³
~13.5% elongation is ensured, whereas Ti
Such high specific strength cannot be obtained with -6Al-4V and Ti-6Al-2Sn-4Zr-2Mo alloys. Further, in the case of Ti-6Al-2Sn-4Zr-6Mo alloy, when the specific strength increases to 29.9 Kgf/mm ² /g/cm ³ , the elongation decreases to 5.2%. In addition, the Ti alloy of the present invention has a superplastic elongation of 410 to 680%, and a maximum deformation stress of 2.9 to 3.3 Kgf/mm ²
This alloy is suitable for superplastic processing. This property is similar to the existing Ti−6Al−2Sn−4Zr−
Significantly superior to 6Mo alloy. Effects of the invention The Ti alloy of the present invention can be subjected to superplastic processing,
It also has excellent high-temperature specific strength and ductility.
Therefore, by applying superplastic working, parts such as compressor rotors, for example, having excellent properties can be easily manufactured at low cost without cutting work. Moreover, by using this, excellent effects such as making it possible to reduce the weight and increase the efficiency of various gas turbines such as jet engines and power generation equipment can be obtained.

Claims

[Claims]

1% by weight, Al5.4~6.6%, V1.3~3.1%,
Sn0.7~1.1%, Zr0.7~5.3%, Mo2.2~2.6%,
A titanium alloy containing 2.4 to 3.7% Cr, 1.4 to 2.8% Fe, and 0.10 to 0.16% O, with the remainder substantially consisting of Ti, and the volume fraction of the α phase at 800°C is 30 to 70%.
A high-strength, heat-resistant titanium alloy suitable for superplastic processing.