JPS6158544B2

JPS6158544B2 -

Info

Publication number: JPS6158544B2
Application number: JP10635684A
Authority: JP
Inventors: Hidehiro Onodera; Toshihiro Yamagata; Yoshiichi Ro; Michio Yamazaki
Original assignee: KAGAKU GIJUTSUCHO KINZOKU ZAIRYO GIJUTSU KENKYU SHOCHO
Current assignee: KAGAKU GIJUTSUCHO KINZOKU ZAIRYO GIJUTSU KENKYU SHOCHO
Priority date: 1984-05-28
Filing date: 1984-05-28
Publication date: 1986-12-12
Also published as: JPS60251240A

Description

[Detailed description of the invention]

産業上の利用分野本発明は超塑性加工用高強度チタン合金に関す
る。更に詳しくは900℃でα相を30〜70％含み、
残部はβ相からなり、高温比強度及び延性に優れ
た超塑性加工用チタン合金に関する。従来、Ti合金部品は鍜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
製造の場合には、切削くずが約90％程度にもな
り、極めて歩留りも悪いばかりでなく、作業性も
極めて悪い。これを改善するためには合金の超塑
性加工が有効な手段である。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900℃附近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900℃より
低温では粒界辷りが起きにくくなるため、超塑性
特性が劣化し、また変形応力が高くなるため、超
塑性加工が困難となる。従来技術従来の超塑性加工用チタン合金としては、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用チタン合金の欠点
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、かつ高温強度及び延性の優れた超塑
性加工用チタン合金を提供するにある。発明の構成本発明の超塑性加工用高強度チタン合金は、重
量％でAl 5.2〜6.0％、V0.4〜1.0％、Sn1.2〜2.8
％、Zr3.2〜5.6％、Mo0.5〜1.2％、Cr0.5〜1.4
％、Fe0.8〜1.5％、O₂0.10〜0.15％を含み、残部
は実質的にTiよりなる組成の合金である。この
合金は900℃でα相を30〜70％含み、残部はβ相
からなる合金である。本発明の合金における組成成分の作用ならびに
組成割合、の限定理由は次の通りである。 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。Al量が5.2％（以下％は重量％を
示す）より少いとα相強化の効果が十分得られな
く、その量が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5.2
〜6.0％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。Ｖ量が0.4％より少いと強化
効果が十分得られなく、その量が1.0％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0.4〜1.0％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。Sn
量が1.2％より少いと強化効果が十分得られな
く、その量が2.8％を超えると比重が大きくなり
比強度が低下するのでSnは1.2〜2.8％であること
が必要である。またZr量が3.2％より少いと強化
効果が得られなく、その量が5.6％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、Zr量は3.2〜5.6％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。Mo量が0.5％より少いと
十分な強化効果が得られなく、その量が1.2％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0.5〜1.2％であることが必要であ
る。Cr量が0.5％より少いと十分な強化効果が得
られなく、その量が1.4％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いので、Cr
量は0.5〜1.4％であることが必要である。Fe量が
0.8％より少いと十分な強化効果が得られなく、
その量が1.2％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、Fe量は0.8
〜1.2％であることが必要である。 O₂は主としてα相に固溶してα相を強化する
作用をする。O₂量が0.10％より少いとその強化効
果が十分得られなく、その量が0.15％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O₂量は0.10〜0.15％であることが必要で
ある。以上のような各元素を前記割合に含ませたチタ
ン合金は900℃においてα相が30〜70％で残部が
β相のものとなる。α相とβ相は互に結晶粒の成
長をさまたげ、超塑性特性を向上させる。α相が
30％より少なくなると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相の結晶粒が粗大化し易くなるため超
塑性特性が劣化する。従つて、本発明のチタン合
金は超塑性加工を行うために十分な特性を有し、
かつ高温比強度と延性を有するものである。実施例本発明のチタン合金の２種類と比較合金及び既
存合金をアーク溶解により作り、高温引張試験と
超塑性試験を行つた。各試験した合金の組成は表
１に示す通りであつた。各合金について溶解、鍜
造後、900℃で約85％の熱間圧延後、６mmφ引張
試験片及び５mmφ超塑性試験片を作つた。高温引張試験片は900℃〜850℃で１時間処理し
た後、水冷し、再び500〜600℃で４時間処理した
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。超塑性試験片は900℃で１時間処理した後水冷
して試験に供した。超塑性試験は900℃でアルゴ
ン雰囲気中で6.7×10^-4S^-1の歪速度で行つた。そ
の結果は表２及び表３に示す通りであつた。 INDUSTRIAL APPLICATION FIELD The present invention relates to a high strength titanium alloy for superplastic working. More specifically, it contains 30 to 70% α phase at 900℃,
The remainder consists of the β phase, and the present invention relates to a titanium alloy for superplastic working that has excellent high-temperature specific strength and ductility. Traditionally, Ti alloy parts have been manufactured by forging or cutting, but when manufacturing compressor rotors, cutting waste amounts to approximately 90%, which not only results in extremely low yields but also reduces workability. is also extremely bad. In order to improve this, superplastic working of alloys is an effective 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. Also, a temperature around 900℃ is suitable for superplastic processing temperature. 900℃
At higher temperatures, grain coarsening and oxidation tend to occur, resulting in deterioration of superplastic properties. Furthermore, at temperatures lower than 900°C, grain boundary sliding becomes less likely to occur, resulting in deterioration of superplastic properties and increased deformation stress, making superplastic processing difficult. Conventional technology As a conventional titanium alloy for superplastic working, Ti
-6Al-4V alloy, Ti-6Al-2Sn-4Zr-2Mo alloy, Ti-6Al-2Sn-4Zr-6Mo alloy, etc. are known. However, all of these titanium alloys are β-type
It had the disadvantage of lower strength than Ti alloys. Purpose of the Invention The present invention aims to improve the drawbacks of conventional titanium alloys for superplastic working, and its purpose is to provide a titanium alloy for superplastic working that has excellent superplastic properties, high-temperature strength, and ductility. There is something to do. Structure of the Invention The high-strength titanium alloy for superplastic working of the present invention contains Al 5.2 to 6.0%, V 0.4 to 1.0%, and Sn 1.2 to 2.8% by weight.
%, Zr3.2~5.6%, Mo0.5~1.2%, Cr0.5~1.4
%, Fe 0.8 to 1.5%, O ₂ 0.10 to 0.15%, and the balance essentially consists of Ti. This alloy contains 30 to 70% α phase at 900°C, with the remainder consisting of β phase. The reasons for limiting the effects and composition ratios of the compositional components in the alloy of the present invention are as follows. Al mainly forms a solid solution in the α phase and acts to strengthen the α phase. If the amount of Al is less than 5.2% (hereinafter % indicates weight%), the effect of α phase strengthening cannot be obtained sufficiently, and if the amount exceeds 6%, the amount of α phase increases and sufficient superplastic properties cannot be obtained. Al is 5.2.
~6.0% is required. V forms a solid solution in the α phase and β phase and acts to strengthen these phases. If the amount of V is less than 0.4%, sufficient strengthening effect will not be obtained, and if the amount exceeds 1.0%, the amount of α phase will decrease and sufficient superplastic properties will not be obtained, so V should be between 0.4 and 1.0%. is necessary. 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. Sn
If the amount is less than 1.2%, a sufficient reinforcing effect will not be obtained, and if the amount exceeds 2.8%, the specific gravity will increase and the specific strength will decrease, so the Sn content must be 1.2 to 2.8%. Also, if the amount of Zr is less than 3.2%, no strengthening effect can be obtained, and if the amount exceeds 5.6%, α
The amount of Zr needs to be 3.2 to 5.6% because the phase amount decreases and sufficient superplastic properties cannot be obtained. Mo, Cr, and Fe mainly act as solid solutions in the β phase to strengthen the β phase. If the amount of Mo is less than 0.5%, a sufficient strengthening effect will not be obtained, and if the amount exceeds 1.2%, the specific gravity will increase and the specific strength will decrease, so the amount of Mo needs to be between 0.5 and 1.2%. be. If the amount of Cr is less than 0.5%, a sufficient strengthening effect cannot be obtained, and if the amount exceeds 1.4%, the amount of α phase decreases and sufficient superplastic properties cannot be obtained.
The amount should be 0.5-1.4%. The amount of Fe
If it is less than 0.8%, sufficient strengthening effect will not be obtained,
If the amount exceeds 1.2%, the amount of α phase decreases and sufficient superplastic properties cannot be obtained, so the amount of Fe is 0.8%.
~1.2% is required. O ₂ mainly acts as a solid solution in the α phase to strengthen the α phase. If the amount of O ₂ is less than 0.10%, the strengthening effect will not be sufficiently obtained, and if the amount exceeds 0.15%, the amount of α phase will increase and sufficient superplastic properties will not be obtained, so the amount of O ₂ should be 0.10 to 0.15. %. A titanium alloy containing the above-mentioned elements in the proportions described above has 30 to 70% α phase and the remainder β phase at 900°C. 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. Furthermore, if the α phase exceeds 70%, the crystal grains of the α phase tend to become coarse, resulting in deterioration of superplastic properties. Therefore, the titanium alloy of the present invention has sufficient properties to perform superplastic processing,
It also has high-temperature specific strength and ductility. Examples Two types of titanium alloys of the present invention, a comparative alloy, and an existing alloy were made by arc melting and subjected to high-temperature tensile tests and superplasticity tests. The composition of each tested alloy was as shown in Table 1. For each alloy, after melting, forging, and hot rolling at 900°C to approximately 85%, 6 mmφ tensile test pieces and 5 mmφ superplastic test pieces were prepared. The high-temperature tensile test piece was treated at 900°C to 850°C for 1 hour, cooled with water, treated again at 500°C to 600°C for 4 hours, cooled in air, and subjected to the test. High temperature tensile test is 300
It was carried out at a strain rate of 3×10 ⁻⁴ S ⁻¹ at ℃. The superplastic test piece was treated at 900°C for 1 hour, then cooled with water and subjected to the test. Superplasticity tests were conducted at 900°C in an argon atmosphere at a strain rate of 6.7×10 ^-4 S ^-1 . The results were as shown in Tables 2 and 3.

【表】【table】

【表】この試験結果が示すように、GT−10及びGT−
15合金はAl量が5.2％より少いため比強度が低
く、またGT−16合金は900℃におけるα相量が25
％と少いため、超塑性特性が悪い。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。また、本発明Ti合金は300％以上の超塑性伸び
を有し、最大変形応力も2.0と十分低いので、超
塑性加工に適した合金である。発明の効果以上のように本発明のTi合金は超塑性加工が
可能で、かつ高温比強度及び延性に優れた合金で
ある。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、コンプレツサーローター等
の部品を安価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を有する。[Table] As this test result shows, GT-10 and GT-
15 alloy has a low specific strength because the Al content is less than 5.2%, and the GT-16 alloy has an α phase content of 25% at 900℃.
%, the superplastic properties are poor. The Ti alloy of the present invention is the existing Ti-6Al-4V, Ti-
6Al−2Sn−4Zr−2Mo and Ti−6Al−2Sn−4Zr−
It has significantly superior ductility and specific strength compared to 6Mo alloy. Furthermore, the Ti alloy of the present invention has a superplastic elongation of 300% or more and a sufficiently low maximum deformation stress of 2.0, so it is an alloy suitable for superplastic working. Effects of the Invention As described above, the Ti alloy of the present invention is an alloy that can be subjected to superplastic processing and has excellent high-temperature specific strength and ductility. Therefore, by applying superplastic working, parts such as compressor rotors can be manufactured at low cost without cutting work. Further, by using this, it has 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.

Claims

[Claims]

1% by weight, Al 5.2-6.0%, V0.4-1.0%,
Sn1.2~2.8%, Zr3.2~5.6%, Mo0.5~1.2%,
A high-strength titanium alloy for superplastic processing, containing 0.5-1.4% Cr, 0.8-1.5% Fe, 0.10-0.15% _O2 , and the remainder essentially consisting of Ti.