JP5393829B2 - Single crystal nickel-base superalloy with improved creep properties - Google Patents
Single crystal nickel-base superalloy with improved creep properties Download PDFInfo
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- 239000013078 crystal Substances 0.000 title claims description 25
- 229910000601 superalloy Inorganic materials 0.000 title claims description 20
- 229910045601 alloy Inorganic materials 0.000 claims description 40
- 239000000956 alloy Substances 0.000 claims description 40
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 21
- 229910052759 nickel Inorganic materials 0.000 claims description 9
- 229910052702 rhenium Inorganic materials 0.000 claims description 9
- 229910052721 tungsten Inorganic materials 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 8
- 229910052750 molybdenum Inorganic materials 0.000 claims description 8
- 229910052707 ruthenium Inorganic materials 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 229910052719 titanium Inorganic materials 0.000 claims description 7
- 229910052715 tantalum Inorganic materials 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 4
- 239000011159 matrix material Substances 0.000 claims description 4
- 239000002244 precipitate Substances 0.000 claims description 3
- 239000012071 phase Substances 0.000 description 25
- 239000000463 material Substances 0.000 description 22
- 238000012360 testing method Methods 0.000 description 22
- 239000010936 titanium Substances 0.000 description 22
- 238000005728 strengthening Methods 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 13
- 238000000034 method Methods 0.000 description 9
- 239000006104 solid solution Substances 0.000 description 8
- 239000011651 chromium Substances 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 3
- 238000005275 alloying Methods 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000010248 power generation Methods 0.000 description 3
- WUAPFZMCVAUBPE-UHFFFAOYSA-N rhenium atom Chemical compound [Re] WUAPFZMCVAUBPE-UHFFFAOYSA-N 0.000 description 3
- 238000007711 solidification Methods 0.000 description 3
- 230000008023 solidification Effects 0.000 description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 3
- 239000010937 tungsten Substances 0.000 description 3
- 229910001011 CMSX-4 Inorganic materials 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 208000003351 Melanosis Diseases 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 2
- 101000912561 Bos taurus Fibrinogen gamma-B chain Proteins 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- -1 aluminum Chemical compound 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
- C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
- C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
- C22C19/057—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being less 10%
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Description
本発明は、単結晶ニッケル基合金に関するものである。より詳細には、主な強化相であるガンマプライム(γ′)形成元素の添加量を調節し、高温でクリープ(creep)により変形されることに対する抵抗性、及びクリープによる破断寿命を向上させた単結晶ニッケル基超耐熱合金に関するものである。 The present invention relates to a single crystal nickel base alloy. More specifically, the amount of gamma prime (γ ′) forming element, which is the main strengthening phase, was adjusted to improve the resistance to deformation by creep at high temperatures and the rupture life due to creep. The present invention relates to a single crystal nickel-based superalloy.
航空機のエンジンや発電に使用される産業用ガスタービンの主要部品であるブレード（ｂｌａｄｅ）及びベーン（ｖａｎｅ）などにはニッケル基超耐熱合金が広く使用される。その超耐熱合金の中で単結晶状態の超耐熱合金は、多結晶及び一方向凝固の超耐熱合金に比べ、優れたクリープ特性を示し、また優れた耐熱性を有しているので、ガスタービンの最も極限の環境に置かれているブレード及びベーンの素材に使用されている。 Nickel-based superalloys are widely used for blades and vanes, which are the main components of industrial gas turbines used in aircraft engines and power generation. Among the super heat-resistant alloys, the super heat-resistant alloy in a single crystal state exhibits excellent creep characteristics and excellent heat resistance compared to polycrystalline and unidirectionally solidified super heat-resistant alloys. Used in the most extreme environments of blades and vanes.
そのような単結晶超耐熱合金は、Ａｌ、Ｔｉを添加して基地（ｍａｔｒｉｘ）内に規則格子の強化相であるγ′(Ｌ１2構造）を生成させて高温強度を得て、Ｗ、Ｍｏ、Ｒｅなどの合金元素を添加して基地を強化させて使用する。 Such single-crystal superalloy, Al, to obtain high-temperature strength to generate a strengthening phase γ '(L1 2 structure) of ordered lattice in the added within the base (matrix) Ti, W, Mo , Re and other alloying elements are added to strengthen the base.
ところで、地球温暖化のような環境問題が台頭し、ＣＯ2の削減のために、新しい発電方案の研究と共に現在発電方法の効率化の必要性が大きくなっている。このため、ガスタービンの場合作動温度が高まる傾向にある。このような理由で、ガスタービンの部品の中で最も極限の環境で使用されるブレード及びベーンの温度受容性及び高温でのクリープ寿命が重要になっている。したがって、従来より優れた高温クリープ特性を有する単結晶超耐熱合金の開発に対する必要性は高まっている。 By the way, environmental problems such as global warming have emerged, and in order to reduce CO 2 , there is a growing need for efficiency improvement of current power generation methods as well as research on new power generation methods. For this reason, in the case of a gas turbine, the operating temperature tends to increase. For these reasons, the temperature acceptability and creep life at high temperatures of blades and vanes used in the most extreme environments of gas turbine components are important. Therefore, there is an increasing need for the development of a single crystal super heat-resistant alloy having high temperature creep characteristics superior to those of conventional ones.
単結晶超耐熱合金は、合金元素であるＲｅ含量により世代が分類されていて、Ｒｅ含量がない場合は第1世代、３重量％である場合は第２世代、６重量％である場合は第３世代などに分類され、さらにＲｕが添加された第４世代の単結晶合金も開発されている。世代が増加すればするほど温度受容性及び高温クリープ特徴も向上したが、高価な元素であるＲｅ、Ｒｕなどの添加量が増加して合金の価格も上昇した。そのため、現在はＲｅ含量が３％である第２世代の単結晶合金である米国のｃａｎｏｎ ｍｕｓｋｅｇｏｎ社が開発したＣＭＳＸ−４(米国登録特許第４,６４３,７８２号)が商用合金として最も広く使用されている。 Single crystal superalloys are classified according to the Re content, which is an alloying element. If there is no Re content, the first generation is 3% by weight, the second generation is 6% by weight. A fourth generation single crystal alloy, which is classified into three generations and further added with Ru, has also been developed. As the generation increased, the temperature acceptability and high temperature creep characteristics improved, but the amount of expensive elements such as Re and Ru increased and the price of the alloy also increased. Therefore, CMSX-4 (US Patent No. 4,643,782) developed by canon muskegone in the US, which is a second generation single crystal alloy with a Re content of 3%, is the most widely used commercial alloy. Has been.
温度受容性及びクリープ特性に優れた単結晶開発の必要性を満たすため、高価の合金元素の追加的な添加を最大限抑制し、他の合金元素の添加量を調節する方案が効果的な合金設計方法として思われており、高温で使用される部品の場合、先に説明したクリープ破断に到達するクリープ寿命も重要であるが、部品の形態が変わればその本来の用途に持続的な使用が不可能であったり、効率が低くなるため、クリープの変形に対する抵抗性も合金設計に考えなければならない非常に重要な因子であると言える。 In order to meet the need for the development of a single crystal with excellent temperature acceptability and creep properties, an alloy that effectively suppresses the additional addition of expensive alloy elements and adjusts the addition amount of other alloy elements is an effective alloy It is considered as a design method, and in the case of parts used at high temperatures, the creep life to reach the creep rupture described above is also important, but if the form of the part changes, it can be used continuously for its original purpose. Resistance to creep deformation is also a very important factor that must be considered in alloy design because it is impossible or less efficient.
超耐熱合金のクリープ特性を高めるためには、先に説明したように Ｗ、Ｍｏ、Ｒｅなどの固溶強化元素を調節する方法もあるが、基地内に規則格子の強化相であるγ′（Ｌ１2構造）を生成させるＡｌやＴｉ元素の含量を調節して特性を向上させることができる。この場合は、Ｒｅなどの高価の元素を添加させて固溶強化によりクリープを向上させることに比べ、価格上昇を抑える効果があるので、これについて研究が必要な状況である。 In order to improve the creep characteristics of super heat-resistant alloys, there is a method of adjusting solid solution strengthening elements such as W, Mo, Re, etc. as described above, but γ ′ ( The characteristics can be improved by adjusting the content of Al and Ti elements that produce (L1 2 structure). In this case, it is necessary to study this because it has an effect of suppressing the price increase as compared with the case where an expensive element such as Re is added to improve creep by solid solution strengthening.
したがって、本発明が解決しようとする技術的課題は、単結晶ニッケル基超耐熱合金の主な強化相であるガンマプライム形成元素であるＡ１、Ｔｉ含量を調節して高温特性、特にクリープ寿命だけではなく、クリープ変形に対する抵抗性に優れた単結晶ニッケル基超耐熱合金を提供することである。 Therefore, the technical problem to be solved by the present invention is to adjust the contents of A1 and Ti, which are gamma prime forming elements, which are the main strengthening phases of single crystal nickel-based superalloys, to adjust the high temperature characteristics, particularly the creep life alone. And providing a single crystal nickel-based superalloy having excellent resistance to creep deformation.
前記課題を達成するため、本発明のクリープ特性に優れた単結晶ニッケル基超耐熱合金は、重量％でＣｏ:１１.５〜１３.５％、Ｃｒ:３.０〜５.０％、Ｍｏ:０.７〜２.０％、Ｗ:８.５〜１０.５％、Ａｌ:３.５〜５.５％、Ｔｉ:２.５〜４.５％、Ｔａ:６.０〜８.０％、Ｒｅ:２.０〜４.０％、Ｒｕ:０.１〜２.０％であり、残りはＮｉとその他の不可避不純物からなる。この時、Ａ１/Ｔｉ組成比は０.７〜２.２の値を有する。ここで、前記超耐熱合金はγ基地とγ′析出物の混合組織を有することができる。 In order to achieve the above object, the single crystal nickel-base superalloy having excellent creep characteristics according to the present invention is Co: 11.5 to 13.5% by weight, Cr: 3.0 to 5.0%, Mo : 0.7-2.0%, W: 8.5-10.5%, Al: 3.5-5.5%, Ti: 2.5-4.5%, Ta: 6.0-8 0.0%, Re: 2.0-4.0%, Ru: 0.1-2.0%, and the remainder consists of Ni and other inevitable impurities. At this time, the A1 / Ti composition ratio has a value of 0.7 to 2.2. Here, the super heat-resistant alloy may have a mixed structure of γ matrix and γ ′ precipitate.
本発明によるクリープ特性に優れた単結晶ニッケル基超耐熱合金によれば、重量％でＣｏ:１１.５〜１３.５％、Ｃｒ:３.０〜５.０％、Ｍｏ:０.７〜２.０％、Ｗ:８.５〜１０.５％、Ａｌ:３.５〜５.５％、Ｔｉ:２.５〜３.５％、Ｔａ:６.０〜８.０％、Ｒｅ:２.０〜４.０％、Ｒｕ:０.１〜２.０％であり、残りはＮｉとその他の不可避不純物からなる超耐熱合金を単結晶に製造することにより、γ基地とγ′析出物の間の格子定数の差である不整合（ｍｉｓｆｉｔ）を大きくして積層欠陥エネルギーを減ってクリープの破断寿命が増加するだけではなく、クリープの変形に対する抵抗性を示す１％のクリープ到達寿命が顕著に増加した合金を確保することができる。 According to the single crystal nickel-base superalloy having excellent creep characteristics according to the present invention, Co: 11.5 to 13.5%, Cr: 3.0 to 5.0%, Mo: 0.7 to 2.0%, W: 8.5 to 10.5%, Al: 3.5 to 5.5%, Ti: 2.5 to 3.5%, Ta: 6.0 to 8.0%, Re : 2.0 to 4.0%, Ru: 0.1 to 2.0%, and the remainder is made of a super heat-resistant alloy made of Ni and other inevitable impurities into a single crystal. Increased misfit, which is the difference in lattice constant between precipitates, reduces stacking fault energy and increases creep rupture life, but also reaches 1% creep, indicating resistance to creep deformation An alloy having a significantly increased life can be secured.
以下、添付図面を参照して、本発明の好ましい実施例を詳細に説明する。下記に説明する実施例は他の様々な形態に変形でき、本発明の範囲は下記に説明する実施例に限定されるものではない。本発明の実施例は当分野で通常の知識を有する者に、本発明をより完全に説明するため提供するものである。 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below can be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.
以下の実施例では、クリープ特性に優れた単結晶ニッケル基超耐熱合金を説明する。ここで、クリープ特性というのは、超耐熱合金を高温で使用するために必須のクリープ寿命だけではなく、クリープ変形に対する抵抗性とする。前記ニッケル基超耐熱合金は次のような主要な特徴を有する。 In the following examples, a single crystal nickel-based superalloy having excellent creep characteristics will be described. Here, the creep property is not only the creep life essential for using the super heat-resistant alloy at a high temperature, but also resistance to creep deformation. The nickel-base superalloy has the following main features.
本発明によるクリープ特性に優れた単結晶ニッケル基超耐熱合金は、Ａｌ、Ｔｉを添加して規則格子の強化相であるγ′(Ｌ１2構造）をγ相の基地に生成させて高温強度を得て、Ｗ、Ｍｏ、Ｒｅ、Ｒｕなどの合金元素を添加して基地を強化させて得る。特にＴｉ含量を高めてＡｌ含量を低くして積層欠陥エネルギーを変化させてクリープ特性を極大化させ、商用合金に比べて向上したクリープ特性を有することを特徴とする。 Single crystal nickel-base superalloy having excellent creep characteristics according to the present invention, Al, high-temperature strength to produce a strengthening phase gamma 'the (L1 2 structure) to the base of the gamma phase of ordered lattice by the addition of Ti And obtained by strengthening the matrix by adding alloying elements such as W, Mo, Re, and Ru. In particular, the Ti content is increased and the Al content is decreased to change the stacking fault energy to maximize the creep characteristics, which is improved in comparison with commercial alloys.
本発明によるニッケル基超耐熱合金は、まず、通常の真空誘導溶解方法により母合金を製作する。その後、製作した母合金の各々に対し、一方向凝固炉を利用してブリッジマン（ｂｒｉｄｇｍａｎ）方法により単結晶の試料を製作する。その試料を熱処理してγとγ′の２つの相からなる微細組織を得ることができる。 In the nickel-base superalloy according to the present invention, first, a mother alloy is manufactured by a normal vacuum induction melting method. Thereafter, a single crystal sample is manufactured for each of the manufactured master alloys by a bridgman method using a unidirectional solidification furnace. The sample can be heat-treated to obtain a microstructure composed of two phases γ and γ ′.
[合金の組成]
本発明のニッケル基超耐熱合金は、重量％で次のような組成を有していて、ここではそれぞれの組成による数値限定の理由も説明する。下記の重量％はニッケル基合金の全体を100とした時、添加される量を重量で換算したものである。説明の便宜のために、ニッケル基とその他の不可避不純物に対する説明は省略する。
[Alloy composition]
The nickel-base superalloy according to the present invention has the following composition in weight%, and here, the reason for numerical limitation by each composition will also be explained. The weight% below is calculated by converting the amount added to the nickel-base alloy as 100. For convenience of explanation, explanation of nickel base and other inevitable impurities is omitted.
(１)コバルト（Ｃｏ）: １１.５〜１３.５％
Ｃｏは、固溶強化の役割をすると共にニッケル基超耐熱合金の主な強化相であるγ′の固相線と基地であるγの固相線を変化させ、溶体化処理が可能な温度に影響を与える。また、高温耐蝕性を向上させる。Ｃｏ含量が１１.５％より低ければクリープ特性が低くなり、１３.５％以上を超えると溶体化処理が可能な温度領域が小さくなり、熱処理の条件を決定することが難しくなる。
(1) Cobalt (Co): 11.5 to 13.5%
Co plays a role in solid solution strengthening and changes the solid phase line of γ ′, which is the main strengthening phase of nickel-base superalloys, and the solid phase line of γ, which is the base, to a temperature at which solution treatment is possible. Influence. It also improves high temperature corrosion resistance. When the Co content is lower than 11.5%, the creep characteristics are lowered. When the Co content exceeds 13.5%, the temperature range in which the solution treatment can be performed becomes small, and it becomes difficult to determine the conditions for the heat treatment.
(２)クロム（Ｃｒ）: ３.５〜５.０％
クロムは、超耐熱合金で耐蝕性を向上させる役割をする一方、炭化物やＴＣＰ（Ｔｏｐｏｌｏｇｉｃａｌｌｙ Ｃｌｏｓｅ Ｐａｃｋｅｄ）相を生成し得、耐熱性には寄与できないために量が制限される。３.５％より少なく添加すれば耐蝕性に問題が発生し、５.０％以上添加すればクリープ特性が低下し、高温で長時間露出時、機械的な特性に悪影響を与えるＴＣＰ相が生成され得る。
(2) Chromium (Cr): 3.5-5.0%
Chromium plays a role in improving corrosion resistance in a super heat-resistant alloy, but can generate carbides and TCP (Topologically Closed Packed) phases, and its amount is limited because it cannot contribute to heat resistance. Addition of less than 3.5% causes a problem in corrosion resistance, and addition of 5.0% or more deteriorates creep characteristics, producing a TCP phase that adversely affects mechanical properties when exposed at high temperatures for long periods of time. Can be done.
(３)モリブデン(Ｍｏ): ０.７〜２.０％
モリブデンは固溶強化の元素で、超耐熱合金の高温特性を向上させる役割をする。しかし、多量に添加すれば密度が高くなり、ＴＣＰ相が生成され得る。０.７％以下では固溶強化の効果を期待しにくく、２.０％以上添加すれば密度が増加する。
(3) Molybdenum (Mo): 0.7 to 2.0%
Molybdenum is a solid solution strengthening element that plays a role in improving the high temperature characteristics of superalloys. However, if added in a large amount, the density increases and a TCP phase can be generated. If it is 0.7% or less, it is difficult to expect the effect of solid solution strengthening, and if 2.0% or more is added, the density increases.
(４)タングステン(Ｗ): ８.５〜１０.５％
タングステンは、固溶強化によりクリープ強度を高める元素である。しかし、多量に添加すれば密度が高くなり、靱性及び耐蝕性が低下し、相安定性が低下する。また、単結晶及び一方向凝固時、フレックル（ｆｒｅｃｋｌｅ）のような鋳造欠陥が発生する可能性が増加する。したがって、高温強度のために８.５％以上のタングステンを添加し、多量に添加する場合に生じる望ましくない効果を抑制するために１０.５％に含量を制限する。
(4) Tungsten (W): 8.5 to 10.5%
Tungsten is an element that increases the creep strength by solid solution strengthening. However, if added in a large amount, the density becomes high, the toughness and the corrosion resistance are lowered, and the phase stability is lowered. Also, during single crystal and unidirectional solidification, the likelihood of casting defects such as freckle increases. Therefore, 8.5% or more of tungsten is added for high temperature strength, and the content is limited to 10.5% in order to suppress an undesirable effect that occurs when a large amount is added.
(５)アルミニウム（Ａｌ）: ３.５〜５.５％
アルミニウムは、ニッケル基超耐熱合金の主な強化相であるγ′の構成元素であるから、高温のクリープ特性の向上に必ず必要な元素である。また、耐酸化性の向上にも寄与する。しかし、３.５％以下ではクリープ強度が低下し、５.５％以上添加する場合は過度なγ′相の析出により機械的な特性を低下し得る。Ａｌの場合、組成の絶対量も重要であるが、他のγ′相の生成元素であるＴｉ含量との関係も重要である。
(5) Aluminum (Al): 3.5 to 5.5%
Since aluminum is a constituent element of γ ′, which is the main strengthening phase of nickel-base superalloys, it is an essential element for improving high temperature creep characteristics. It also contributes to the improvement of oxidation resistance. However, if it is 3.5% or less, the creep strength is lowered, and if it is added 5.5% or more, mechanical properties can be lowered due to excessive precipitation of the γ 'phase. In the case of Al, the absolute amount of the composition is also important, but the relationship with the Ti content which is another element forming the γ ′ phase is also important.
(６)チタニウム（Ｔｉ）:２.５〜４.５％
チタニウムはアルミニウムと同様にγ′相の構成元素で、クリープ強度の向上を助ける。特にＴｉ添加により不整合（ｍｉｓｆｉｔ）が大きくなり積層欠陥エネルギーが小さくなるので、２.５％以上添加してクリープ特性を向上させるようにする。しかし、過度に添加する場合には耐酸化性が減少されて相安定性が低下されるので４.５％に制限する。
(6) Titanium (Ti): 2.5-4.5%
Titanium, like aluminum, is a constituent element of the γ 'phase and helps improve creep strength. In particular, the addition of Ti increases the misfit and decreases the stacking fault energy, so 2.5% or more is added to improve the creep characteristics. However, when it is added excessively, the oxidation resistance is reduced and the phase stability is lowered, so it is limited to 4.5%.
(７)タンタル（Ｔａ）: ６.０〜８.０％
タンタルは、主な強化相であるγ′相に固溶されてγ′相を強化させる役割をし、クリープ強度の向上に寄与する。また、樹枝状間領域に偏析されてこの領域の密度を高めるので、鋳造欠陥であるフレックル生成を抑制することもする。したがって、６.０％以上の含量が必要である。しかし、８.０％以上添加する場合、δ相が析出されることがあり特性を低下させる。
(7) Tantalum (Ta): 6.0-8.0%
Tantalum serves to strengthen the γ ′ phase by being dissolved in the γ ′ phase, which is the main strengthening phase, and contributes to the improvement of the creep strength. Moreover, since it is segregated in the region between dendrites and the density of this region is increased, the generation of freckle which is a casting defect is also suppressed. Therefore, a content of 6.0% or more is necessary. However, when added in an amount of 8.0% or more, the δ phase may be precipitated, deteriorating the characteristics.
(８)レニウム（Ｒｅ）: ２.０〜４.０％
レニウムは固溶強化の元素で、拡散速度が非常に遅いために、クリープ特性の向上に大きく寄与する。言い換えて、レニウムを添加することにより、超耐熱合金は高温で使用するために必須のクリープ寿命だけではなく、クリープ変形に対する抵抗性が大きく向上される。しかし、多量に含有すれば、相安定性が低下して密度が大きくなり、価格も高いので、本発明では２.０〜４.０％の範囲を有するように制限する。
(8) Rhenium (Re): 2.0-4.0%
Rhenium is a solid solution strengthening element, and its diffusion rate is very slow, so it greatly contributes to the improvement of creep characteristics. In other words, the addition of rhenium greatly improves the resistance to creep deformation as well as the creep life essential for the super heat resistant alloy to be used at high temperatures. However, if it is contained in a large amount, the phase stability is lowered, the density is increased, and the price is high. Therefore, in the present invention, the content is limited to 2.0 to 4.0%.
(９)ルテニウム（Ｒｕ）: ０.１〜２.０％
ルテニウムは固溶強化の元素で作用して基地を強化させる。γ′相が固溶され得る領域を広めて偏析の均質化に寄与し、ＴＣＰ相の生成を抑制するなど、高温特性を改善させる。これにより、本発明では超耐熱合金を高温で使用するために必須のクリープ寿命だけではなく、クリープ変形に対する抵抗性を高めるためにこれを添加する。しかし、ルテニウムが多量に含有すれば、合金の価格も高くなり、密度が増加するので０.１〜２.０％の範囲で添加する。
(9) Ruthenium (Ru): 0.1-2.0%
Ruthenium works with solid solution strengthening elements to strengthen the base. Widens the region where the γ ′ phase can be dissolved, contributes to homogenization of segregation, and improves high temperature characteristics such as suppressing the generation of TCP phase. Accordingly, in the present invention, not only the creep life essential for using the super heat-resistant alloy at a high temperature but also the resistance to creep deformation is added to increase the resistance. However, if a large amount of ruthenium is contained, the price of the alloy increases, and the density increases. Therefore, it is added in the range of 0.1 to 2.0%.
以下、実施例を通して本発明をより詳細に説明する。 Hereinafter, the present invention will be described in more detail through examples.
表１は、本発明の実施例が適用された単結晶超耐熱合金と前記超耐熱合金、また比較合金の化学組成を示したものである。 Table 1 shows the chemical compositions of the single crystal super heat resistant alloy to which the examples of the present invention were applied, the super heat resistant alloy, and the comparative alloy.
表１によれば、試験材１はＡ１とＴｉ がそれぞれ４.５重量％、３.０重量％添加されたニッケル基合金の組成を示したものであり、試験材２は Ａ１とＴｉがそれぞれ５.０重量％、２.５重量％である場合を示したものである。一方、比較試験材１は Ａ１とＴｉ がそれぞれ５.５重量％、１.０重量％添加した合金であり、比較試験材２は現在最も広く使用されている商用の単結晶合金のＣＭＳＸ-４である。 According to Table 1, test material 1 shows the composition of a nickel-based alloy to which A1 and Ti are added by 4.5% by weight and 3.0% by weight, respectively, and test material 2 has A1 and Ti respectively. The case of 5.0% by weight and 2.5% by weight is shown. On the other hand, the comparative test material 1 is an alloy to which A1 and Ti are added in an amount of 5.5% by weight and 1.0% by weight, respectively, and the comparative test material 2 is the most widely used commercial single crystal alloy CMSX-4. It is.
前記試験材と比較試験材は、まず、通常の真空誘導溶解方法により母合金を製作した後、製作した母合金の各々に対し、一方向凝固炉を利用してブリッジマン方法により、一つのモールドに直径１５ｍｍ、長さ１８０ｍｍの棒状の試料が６個付いている単結晶のモールドを利用し、４.０ｍｍ／ｍｉｎの速度で引き出して単結晶の試料を製作した。その試料を熱処理によりγとγ′の２つの相からなる微細組織を得た。 The test material and the comparative test material are prepared by first manufacturing a mother alloy by a normal vacuum induction melting method, and then by using a unidirectional solidification furnace for each of the manufactured mother alloys, one mold by a Bridgeman method. Using a single crystal mold with six rod-shaped samples having a diameter of 15 mm and a length of 180 mm, a single crystal sample was produced by pulling out at a speed of 4.0 mm / min. The sample was heat-treated to obtain a microstructure composed of two phases γ and γ ′.
表２は、前記合金を９５０℃で３５５ＭＰａの応力を加えてクリープ試験を行った時、クリープ寿命と１％のクリープ延伸に到達する時までの寿命を示したものである。図１は、表２で示した条件でクリープ試験を行った場合、時間によるクリープ変形量の変化とクリープ寿命を示すグラフである。 Table 2 shows the creep life and the life until reaching the 1% creep extension when the alloy was subjected to a creep test by applying a stress of 355 MPa at 950 ° C. FIG. 1 is a graph showing the change in creep deformation with time and the creep life when a creep test is performed under the conditions shown in Table 2.
表２と図１から分かるように、ニッケル基合金のクリープ特性はガンマプライム形成元素であるＡ１、Ｔｉ含量に大きく依存する。すなわち、Ｔｉ含量 は相対的に高くてＡ１含量は相対的に低い試験材１は、他の試験材や比較試験材よりクリープ破断時間と１％のクリープ変形到達時間が顕著に大きいということが分かる。もちろん、このようなガンマプライム形成元素の含量を調節してクリープ特性を向上させるためには、他の合金元素の含量を最適化する過程が必要である。 As can be seen from Table 2 and FIG. 1, the creep characteristics of the nickel-base alloy greatly depend on the contents of A1 and Ti which are gamma prime forming elements. That is, it can be seen that the test material 1 having a relatively high Ti content and a relatively low A1 content has a significantly longer creep rupture time and 1% creep deformation arrival time than other test materials and comparative test materials. . Of course, in order to improve the creep characteristics by adjusting the content of such a gamma prime forming element, a process for optimizing the content of other alloy elements is required.
具体的に、Ｔｉ含量を高めてＡ１含量を低くした試験材１と試験材２のクリープ破断時間は２７０.２〜３０１.８時間であり、１％のクリープ変形到達時間は１５１.９〜１９７.０時間であった。一方、Ｔｉ含量が低くてＡ１含量が高い比較試験材１〜２はクリープ破断時間が１２３.１〜２１１.７時間であり、１％のクリープ変形到達時間は５７.０〜１１２.０時間であった。したがって、本発明の試験材１は、比較試験材１、２よりクリープ破断時間とクリープ変形到達時間が増加したことが分かった。 Specifically, the creep rupture time of Test Material 1 and Test Material 2 in which the Ti content is increased and the A1 content is decreased is 270.2-301.8 hours, and the creep deformation arrival time of 1% is 151.9-197. It was 0.0 hours. On the other hand, the comparative test materials 1 and 2 having a low Ti content and a high A1 content have a creep rupture time of 123.1 to 211.7 hours, and a 1% creep deformation arrival time of 57.0 to 112.0 hours. there were. Therefore, it was found that the test material 1 of the present invention increased the creep rupture time and the creep deformation arrival time compared to the comparative test materials 1 and 2.
図２は、本発明の試験材１と比較材１及び比較材２のクリープ試験後、ＴＥＭ（Ｔｒａｎｓｍｉｓｓｉｏｎ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ）で観察した微細組織を示した写真である。 FIG. 2 is a photograph showing the microstructure observed by TEM (Transmission Electron Microscope) after the creep test of the test material 1, the comparative material 1 and the comparative material 2 of the present invention.
図２によれば、比較材１と比較材２の場合、クリープ試験後、強化相である γ′内部に主に超転位（ｓｕｐｅｒｄｉｓｌｏｃａｔｉｏｎ）が観察されているが、試験材１の場合、積層欠陥が観察される。これは、Ｔｉ含量増加により積層欠陥エネルギーが低くなって積層欠陥が生成されやすくなったためである。この時、完全転位(ｐｅｒｆｅｃｔ ｄｉｓｌｏｃａｔｉｏｎ)が部分転位（ｐａｒｔｉａｌ ｄｉｓｌｏｃａｔｉｏｎ）と、これで囲まれた積層欠陥に分解されるので転位が移動しにくくなり、クリープ変形に対する抵抗性が大きくなる。したがって、Ｔｉ含量の増加によりクリープ特性が改善されることが分かる。 According to FIG. 2, in the case of the comparative material 1 and the comparative material 2, after the creep test, superdislocation is mainly observed inside the strengthening phase γ ′. Is observed. This is because a stacking fault energy is easily generated due to a decrease in stacking fault energy due to an increase in Ti content. At this time, the perfect dislocation is decomposed into the partial dislocation and the stacking fault surrounded by the dislocation, so that the dislocation is difficult to move and resistance to creep deformation is increased. Therefore, it can be seen that the creep characteristics are improved by increasing the Ti content.
以上、本発明は好ましい実施例を挙げて詳細に説明したが、本発明は前記実施例に限定されず、本発明の技術思想の範囲内で当分野で通常の知識を有する者により様々な変形が可能である。 The present invention has been described in detail with reference to the preferred embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications may be made by those having ordinary knowledge in the art within the scope of the technical idea of the present invention. Is possible.
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| KR102114253B1 (en) * | 2018-02-26 | 2020-05-22 | 한국기계연구원 | Ni based superalloy with high creep strength and manufacturing method thereof |
| CN111027198B (en) * | 2019-12-03 | 2022-07-19 | 西北工业大学 | A creep-life prediction method for nickel-based single crystal alloys considering topologically close-packed phase evolution |
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| US6007645A (en) * | 1996-12-11 | 1999-12-28 | United Technologies Corporation | Advanced high strength, highly oxidation resistant single crystal superalloy compositions having low chromium content |
| JPH11310839A (en) * | 1998-04-28 | 1999-11-09 | Hitachi Ltd | High-strength Ni-base superalloy directionally solidified casting |
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| JP3944582B2 (en) * | 2003-09-22 | 2007-07-11 | 独立行政法人物質・材料研究機構 | Ni-base superalloy |
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| SE528807C2 (en) * | 2004-12-23 | 2007-02-20 | Siemens Ag | Component of a superalloy containing palladium for use in a high temperature environment and use of palladium for resistance to hydrogen embrittlement |
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