JP5868685B2 - Structural member temperature estimation method and structural member maintenance method - Google Patents
Structural member temperature estimation method and structural member maintenance method Download PDFInfo
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本発明は、ガスタービンの動翼をはじめとするＮｉ基耐熱合金で構成された構造部材の温度推定方法及び構造部材の保全方法に関するものである。 The present invention relates to a temperature estimation method for a structural member made of a Ni-base heat-resistant alloy such as a moving blade of a gas turbine, and a maintenance method for the structural member.
一般的に、例えばガスタービンやジェットエンジンの動静翼等の構造部材は、高温環境下で使用され、さらには応力が作用していることから、長期運転に伴ってクリープ損傷をはじめとする各種劣化が避けられない。このような劣化が進行すると構造部材が破損に至るため、高温で使用される構造部材の信頼性を確保するとともに安定運用を図るべく、構造部材の温度を精度良く推定し、適切な保守管理を行うことが重要である。 In general, structural members such as gas turbines and moving blades of jet engines are used in high-temperature environments, and since stress is acting on them, various types of deterioration such as creep damage occur with long-term operation. Is inevitable. If such deterioration progresses, the structural member will be damaged. Therefore, in order to ensure the reliability of the structural member used at high temperatures and to ensure stable operation, the temperature of the structural member is accurately estimated and appropriate maintenance management is performed. It is important to do.
これまでに、構造部材の温度を推定する方法として、構造部材の表面近傍における特定の金属組織を評価することにより、推定する方法が用いられている。その推定方法は、まず予め実験で特定の金属組織と温度及び時間との関係を求めて、温度を推定するための指標を設定しておく。そして、実機の構造部材の金属組織を指標と対応させることにより、温度を推定する。 So far, as a method of estimating the temperature of the structural member, a method of estimating by evaluating a specific metal structure in the vicinity of the surface of the structural member has been used. In the estimation method, first, a relationship between a specific metal structure, temperature, and time is obtained in advance by an experiment, and an index for estimating the temperature is set. Then, the temperature is estimated by associating the metal structure of the structural member of the actual machine with the index.
例えば、特許文献１では、表面に耐熱性のコーティング膜が形成された構造部材において、特定の金属組織として酸化スケール層、析出物の消失深さ、拡散層の厚さを測定することにより、温度を推定することを提案している。
また、特許文献２では、特定の金属組織として、γ’（ガンマプライム、Ｎｉ３（Ａｌ、Ｔｉ））相に着眼し、γ’相の粒径を測定することにより、構造部材の温度を推定することを提案している。
For example, in Patent Document 1, in a structural member having a heat-resistant coating film formed on the surface, the oxide layer, the disappearance depth of the precipitate, and the thickness of the diffusion layer are measured as a specific metal structure, thereby measuring the temperature. It is proposed to estimate
In Patent Document 2, the temperature of the structural member is estimated by focusing on the γ ′ (gamma prime, Ni 3 (Al, Ti)) phase as a specific metal structure and measuring the particle size of the γ ′ phase. Propose to do.
ところで、特許文献１に記載の方法は、構造部材の表面にコーティング膜が形成されている場合にしか適用できず、コーティング膜が形成されていないＮｉ基耐熱合金で構成された構造部材の温度を推定することができない。一般的に、高温環境で使用されるガスタービンの動翼等では表面にコーティング膜が形成されているが、例えば冷却孔等の部位ではコーティング膜は形成されていない。このような部位においては、特許文献１の方法を適用し温度を推定することは不可能である。 By the way, the method described in Patent Document 1 can be applied only when a coating film is formed on the surface of the structural member, and the temperature of the structural member made of a Ni-based heat-resistant alloy with no coating film formed thereon is set. Cannot be estimated. Generally, a coating film is formed on the surface of a moving blade or the like of a gas turbine used in a high-temperature environment, but no coating film is formed at a site such as a cooling hole. In such a part, it is impossible to estimate the temperature by applying the method of Patent Document 1.
また、特許文献２に記載の方法では、特定の金属組織として、γ’相の粒径を測定しているが、このγ’相の粒径の変化は７５０℃以上の高温域で顕著に生じる。そのため、７５０℃未満の温度域においては、γ’相の粒径の変化がほとんど生じないため、構造部材の温度を推定することが困難である。Ｎｉ基耐熱合金で構成された構造部材であっても、使用環境によっては、７５０℃以下の温度域でも劣化が生じて破損に至る場合があり、このような温度域でも温度を推定可能な構造部材の温度推定方法が求められている。 Further, in the method described in Patent Document 2, the particle size of the γ ′ phase is measured as a specific metal structure, but the change in the particle size of the γ ′ phase is significantly generated in a high temperature range of 750 ° C. or higher. . Therefore, in the temperature range below 750 ° C., the change in the particle size of the γ ′ phase hardly occurs, and it is difficult to estimate the temperature of the structural member. Even a structural member made of a Ni-base heat-resistant alloy may be damaged even in a temperature range of 750 ° C. or lower depending on the use environment, and the temperature can be estimated even in such a temperature range. There is a need for a temperature estimation method for members.
この発明は前述した事情に鑑みてなされたものであって、ガスタービンの動翼をはじめとするＮｉ基耐熱合金で構成された構造部材の温度を、広い温度範囲にわたって推定可能な構造部材の温度推定方法、及びこの温度推定方法を用いた構造部材の保全方法を提供することを目的とする。 The present invention has been made in view of the circumstances described above, and the temperature of a structural member that can estimate the temperature of a structural member made of a Ni-base heat-resistant alloy such as a moving blade of a gas turbine over a wide temperature range. It is an object of the present invention to provide an estimation method and a structural member maintenance method using the temperature estimation method.
本発明者らは、上記課題を解決すべく鋭意研究した結果、高温環境で使用されるＮｉ基耐熱合金では、表層近傍において、γ’相が消失した変質層が形成されていることが明らかとなった。そして、さらに検討を進めた結果、このγ’相が消失した変質層は、温度及び時間と相関があることを見出し、本発明を完成させるに至った。
すなわち本発明は、母相及びγ’相を有するＮｉ基耐熱合金で構成された構造部材の温度を推定する温度推定方法であって、前記構造部材の表層のＡｌが空気中の酸素と結合して形成されたアルミナ及び該アルミナの形成による前記母材からの前記Ａｌの減少に伴って前記γ’相が前記母相に固溶した層からなる変質層の厚さと、温度及び時間の関係を示した指標を定め、前記構造部材における前記変質層の厚さを測定し、該測定値を前記指標と対応させて、前記構造部材の推定温度を算出することを特徴としている。
As a result of diligent research to solve the above problems, the inventors of the present invention clearly found that in the Ni-base heat-resistant alloy used in a high-temperature environment, an altered layer in which the γ ′ phase has disappeared is formed in the vicinity of the surface layer. became. As a result of further investigation, the altered layer from which the γ ′ phase disappeared was found to have a correlation with temperature and time, and the present invention was completed.
That is, the present invention is a temperature estimation method for estimating the temperature of a structural member made of a Ni-base heat-resistant alloy having a parent phase and a γ ′ phase , wherein Al on the surface layer of the structural member is combined with oxygen in the air. The relationship between the temperature and time, the thickness of the altered layer composed of the alumina formed in this manner, and the layer of the γ 'phase dissolved in the matrix as the Al decreases from the matrix due to the formation of the alumina , The indicated index is defined, the thickness of the deteriorated layer in the structural member is measured, and the estimated temperature of the structural member is calculated by associating the measured value with the index.
本発明の構造部材の温度推定方法によれば、構造部材のγ’相が消失した変質層の厚さを、予め定めた変質層の厚さと温度及び時間の関係を示した指標に対応させて構造部材の温度を推定する。こうすることにより、構造部材の温度を広い温度範囲にわたって精度良く評価することが可能となる。 According to the temperature estimation method for a structural member of the present invention, the thickness of the altered layer in which the γ ′ phase of the structural member has disappeared is associated with a predetermined index indicating the relationship between the altered layer thickness, temperature, and time. Estimate the temperature of the structural member. By doing so, the temperature of the structural member can be accurately evaluated over a wide temperature range.
また、前記変質層の厚さとして、γ’相の固溶した層の厚さを測定する構成とされても良い。
この場合、Ｎｉ基耐熱合金中に分散しているγ’相の析出の有無により、変質層の厚さを測定するので、容易に変質層の厚さを評価することが可能である。また、γ’相の固溶した層の厚さを測定する構成とされているので、正確に変質層の厚さを測定し、構造部材の温度の推定精度を向上させることができる。
Further, as the thickness of the altered layer, the thickness of the layer in which the γ ′ phase is dissolved may be measured.
In this case, since the thickness of the deteriorated layer is measured based on the presence or absence of precipitation of the γ ′ phase dispersed in the Ni-base heat-resistant alloy, it is possible to easily evaluate the thickness of the deteriorated layer. In addition, since the thickness of the layer in which the γ ′ phase is dissolved is measured, the thickness of the altered layer can be accurately measured to improve the estimation accuracy of the temperature of the structural member.
また、前記指標は、Ｄ＝ｋ０・ｅｘｐ（−Ｑ／ＲＴ）・ｔ１／２、Ｄ：変質層の厚さ、Ｑ：活性化エネルギー、Ｔ：絶対温度、ｔ：時間、ｋ０：定数、として表される式を用いても良い。
このような式に基づいて構造部材の温度を算出する場合、測定した構造部材の変質層の厚さから容易に構造部材の温度を推定することができる。また、上記の式は、熱活性化過程に基づいて算出される式であるので、構造部材の温度の推定精度を向上させることが可能となる。
The index is D = k 0 · exp (−Q / RT) · t 1/2 , D: thickness of the altered layer, Q: activation energy, T: absolute temperature, t: time, k 0 : An expression expressed as a constant may be used.
When calculating the temperature of a structural member based on such an equation, the temperature of the structural member can be easily estimated from the measured thickness of the altered layer of the structural member. Moreover, since said formula is a formula calculated based on a thermal activation process, it becomes possible to improve the estimation accuracy of the temperature of a structural member.
さらに、本発明の構造部材の保全方法は、上述の温度推定方法を、タービンまたはジェットエンジンの動静翼に適用することを特徴としている。
ジェットエンジンやタービンの動静翼は、高温環境において使用され運転中における劣化が生じ破損に至る恐れがある。このような過酷な環境で使用されるタービン動翼等の使用される温度を精度良く評価することによって、保全を効率的に行うことが可能となる。
Furthermore, the structural member maintenance method of the present invention is characterized in that the above-described temperature estimation method is applied to a moving blade and a stationary blade of a turbine or a jet engine.
The moving and stationary blades of a jet engine and a turbine are used in a high temperature environment and may be deteriorated during operation and may be damaged. Maintenance can be efficiently performed by accurately evaluating the temperature at which the turbine rotor blade or the like used in such a harsh environment is used.
本発明によれば、ガスタービンの動翼をはじめとするＮｉ基耐熱合金で構成された構造部材の温度を、広い範囲にわたって推定可能な構造部材の温度推定方法、及びこの温度推定方法を用いた構造部材の保全方法を提供することができる。 According to the present invention, a temperature estimation method for a structural member that can estimate the temperature of a structural member composed of a Ni-base heat-resistant alloy such as a moving blade of a gas turbine over a wide range, and the temperature estimation method are used. A structural member maintenance method can be provided.
以下に、本発明の実施の形態について添付した図面を参照して説明する。
本実施形態は、高温環境で使用されるガスタービンやジェットエンジンの動翼等の構造部材の温度推定方法に関するものである。
Embodiments of the present invention will be described below with reference to the accompanying drawings.
The present embodiment relates to a temperature estimation method for a structural member such as a gas turbine or a moving blade of a jet engine used in a high temperature environment.
本実施形態に係る構造部材は、Ｎｉ基耐熱合金で構成されている。具体的には、ＭＧＡ１４００、ＩＮ７３８ＬＣ、Ｕ５２０、ＭＧＡ２４００等のＡｌ及びＴｉ元素の添加量が多いＮｉ基耐熱合金が挙げられる。これらの合金種は、構造部材に必要な強度、耐熱性、溶接性等に応じて、適宜最適な合金種を選択すれば良い。 The structural member according to the present embodiment is made of a Ni-base heat resistant alloy. Specifically, Ni-based heat-resistant alloys with a large amount of addition of Al and Ti elements such as MGA1400, IN738LC, U520, MGA2400 and the like can be mentioned. These alloy types may be appropriately selected according to the strength, heat resistance, weldability, etc. required for the structural member.
図１（Ａ）は構造部材の初期状態（高温環境に置かれる前）の表層近傍における金属組織の概念図を示している。上述のＮｉ基耐熱合金で構成された構造部材の金属組織は、図１（Ａ）で示すように、母相１０の内部にγ’相１１が析出した金属組織となっている。そして、構造部材の初期状態においては、内部から表層の板厚方向の全領域にわたってγ’相１１が析出している。 FIG. 1A shows a conceptual diagram of the metal structure in the vicinity of the surface layer of the structural member in the initial state (before being placed in a high temperature environment). As shown in FIG. 1A, the metal structure of the structural member made of the above-described Ni-base heat-resistant alloy is a metal structure in which the γ ′ phase 11 is precipitated inside the matrix phase 10. In the initial state of the structural member, the γ ′ phase 11 is deposited from the inside to the entire region in the thickness direction of the surface layer.
γ’相１１の組成は、Ｎｉ３（Ａｌ、Ｔｉ）であり、Ｎｉ基耐熱合金においては、Ａｌ及びＴｉ元素の添加量が多い場合に、γ’相１１が多数析出する。このγ’相１１は高温においても析出状態を維持することができ、Ｎｉ基耐熱合金の高温における高強度化に寄与する析出相となっている。Ｎｉ基耐熱合金においては、このγ’相１１は、数十ｎｍ〜数百ｎｍのサイズで析出している。 The composition of the γ ′ phase 11 is Ni 3 (Al, Ti). In the Ni-based heat-resistant alloy, when the amount of Al and Ti elements added is large, a large number of γ ′ phases 11 are precipitated. This γ ′ phase 11 can maintain a precipitation state even at a high temperature, and is a precipitation phase that contributes to increasing the strength of the Ni-base heat-resistant alloy at a high temperature. In the Ni-base heat-resistant alloy, the γ ′ phase 11 is precipitated with a size of several tens nm to several hundreds nm.
次に、本実施形態の構造部材が高温環境下に曝された後の構造部材の金属組織について説明する。
図１（Ｂ）は、ガスタービンやジェットエンジンの動静翼が長時間運転された後（長時間高温環境に置かれた後）の構造部材の表層近傍における金属組織の概念図を示している。長時間高温環境に曝された構造部材の表層近傍には、図１（Ｂ）で示すように、γ’相１１が消失した変質層（変質層２０）が形成されている。
Next, the metal structure of the structural member after the structural member of this embodiment is exposed to a high temperature environment will be described.
FIG. 1B shows a conceptual diagram of the metal structure in the vicinity of the surface layer of the structural member after the moving and stationary blades of the gas turbine and the jet engine are operated for a long time (after being placed in a high temperature environment for a long time). In the vicinity of the surface layer of the structural member that has been exposed to a high temperature environment for a long time, as shown in FIG. 1B, an altered layer (modified layer 20) from which the γ ′ phase 11 has disappeared is formed.
変質層２０は、最表層側に形成された酸化層２１と、この酸化層２１の下方に形成されたγ’相の固溶した層２２により構成されている。高温環境に長時間置かれた構造部材の表層には、構造部材の初期状態とは異なり、このような変質層２０が形成されている。この変質層２０は、構造部材の使用される環境の温度及び時間が増加するとともに、その厚みが増加する。 The altered layer 20 includes an oxide layer 21 formed on the outermost layer side, and a γ ′ phase solid solution layer 22 formed below the oxide layer 21. Unlike the initial state of the structural member, such a modified layer 20 is formed on the surface layer of the structural member that has been placed in a high temperature environment for a long time. The deteriorated layer 20 increases in thickness as the temperature and time of the environment in which the structural member is used increases.
変質層２０の厚さは次のように測定される。まず、構造部材の温度推定対象となる箇所からサンプルを採取する。次に、採取したサンプルに樹脂埋め等を施した後に断面の研磨及びエッチングを行い、構造部材の表層近傍断面をＳＥＭ（走査型電子顕微鏡）やＴＥＭ（透過型電子顕微鏡）等により観察する。そして、観察した金属組織写真を用いて、構造部材の表層から、γ’相の固溶した層２２とγ’相が析出した領域の境界までの厚さを測定することにより変質層２０の厚みを測定する。 The thickness of the altered layer 20 is measured as follows. First, a sample is taken from a location that is a temperature estimation target of the structural member. Next, after the collected sample is filled with resin or the like, the cross section is polished and etched, and the cross section near the surface layer of the structural member is observed by SEM (scanning electron microscope), TEM (transmission electron microscope) or the like. Then, using the observed metallographic photograph, the thickness of the altered layer 20 is measured by measuring the thickness from the surface layer of the structural member to the boundary between the layer 22 where the γ ′ phase is dissolved and the region where the γ ′ phase is deposited. Measure.
酸化層２１は、アルミナ（Ａｌ２Ｏ３）で構成されており、Ｎｉ基耐熱合金中のＡｌと構造部材と接する空気中の酸素（Ｏ）とが結合することにより表層に生成される。この酸化層２１は、構造部材が使用される環境の温度及び時間が増加するとともに厚みが増加する。 The oxide layer 21 is made of alumina (Al 2 O 3 ), and is generated on the surface layer by combining Al in the Ni-base heat-resistant alloy and oxygen (O) in the air in contact with the structural member. The oxide layer 21 increases in thickness as the temperature and time of the environment in which the structural member is used increases.
γ’相の固溶した層２２は、構造部材の母相中のγ’相１１が固溶することにより形成される層である。このγ’相の固溶した層２２は、構造部材が使用される環境の温度及び時間が増加するとともに厚みが増加する。Ｎｉ基耐熱合金で構成された構造部材では、上述したように、高温環境下に置かれると、空気中の酸素（Ｏ）と構造部材の表層のＡｌが結合し表層にアルミナが形成される。この際に、構造部材の表層では、酸化層にＡｌが排出されるため母相のＡｌが減少し、母相中に析出していたγ’相１１の析出を維持することができなくなり母相にγ’相１１が固溶する。このようにして、上述のようなγ’相の固溶した層２２が形成されることとなる。 The γ ′ phase solid solution layer 22 is a layer formed by the solid solution of the γ ′ phase 11 in the matrix phase of the structural member. This γ ′ phase solid solution layer 22 increases in thickness as the temperature and time of the environment in which the structural member is used increases. In a structural member made of a Ni-base heat-resistant alloy, as described above, when placed in a high temperature environment, oxygen (O) in the air and Al on the surface layer of the structural member combine to form alumina on the surface layer. At this time, in the surface layer of the structural member, since Al is discharged into the oxide layer, Al in the parent phase is reduced, and the precipitation of the γ ′ phase 11 that has been precipitated in the parent phase cannot be maintained. The γ 'phase 11 is dissolved in the solution. In this way, the layer 22 in which the γ ′ phase is dissolved as described above is formed.
以下に、本実施形態の構造部材の温度推定方法の手順について説明する。本実施形態の構造部材の温度推定方法は図２で示すフロー図の手順に従って、高温環境で使用される構造部材の変質層の厚みを測定することにより、構造部材の温度を推定するものである。構造部材の温度を推定するための手順は、例えば、第一の工程Ｓ１０、第二の工程Ｓ２０、第三の工程を備えている。 Below, the procedure of the temperature estimation method of the structural member of this embodiment is demonstrated. The method for estimating the temperature of the structural member according to the present embodiment estimates the temperature of the structural member by measuring the thickness of the altered layer of the structural member used in a high-temperature environment according to the flow chart shown in FIG. . The procedure for estimating the temperature of the structural member includes, for example, a first step S10, a second step S20, and a third step.
（第一の工程）＜Ｓ１０＞
第一の工程Ｓ１０は、予め実験で構造部材の表層に形成された変質層２０の厚さと、温度及び時間の関係を示した予測式（指標）を作成する工程である。
まず、温度推定の評価の対象となる構造部材と同じ組成のＮｉ基耐熱合金のサンプルを用意し、温度（保持温度）と時間（各保持温度での保持時間）を種々に変えて熱処理を行い、サンプル表層における断面の組織観察を行う。そして、断面組織観察写真から、サンプルの表層に形成された変質層２０を測定する。
変質層２０の厚さＤは、時間ｔの１／２乗に比例し、Ｄ＝ｋ・ｔ１／２（Ｄ：変質層の厚さ、ｋ：変質層成長速度定数、ｔ：時間）のように表される。実験により求めた変質層２０の厚さと、温度及び時間の関係を上記した変質層２０の厚さＤの式に対応させて、各温度における変質層成長速度定数ｋを算出する。
(First step) <S10>
The first step S10 is a step of creating a prediction formula (index) showing the relationship between the thickness of the altered layer 20 previously formed on the surface layer of the structural member by experiment and the temperature and time.
First, prepare a sample of Ni-base heat-resistant alloy with the same composition as the structural member to be evaluated for temperature estimation, and perform heat treatment by changing the temperature (holding temperature) and time (holding time at each holding temperature) in various ways. The structure of the cross section of the sample surface layer is observed. Then, the altered layer 20 formed on the surface layer of the sample is measured from the cross-sectional structure observation photograph.
The thickness D of the altered layer 20 is proportional to the 1/2 power of the time t, and D = k · t 1/2 (D: thickness of the altered layer, k: altered layer growth rate constant, t: time) It is expressed as follows. The relationship between the thickness of the deteriorated layer 20 obtained by the experiment, the temperature and the time is associated with the above-described equation for the thickness D of the deteriorated layer 20 to calculate the deteriorated layer growth rate constant k at each temperature.
ここで変質層成長速度定数ｋは、熱活性化過程を表す式であるアレニウスの式ｋ＝ｋ０・ｅｘｐ（−Ｑ／ＲＴ）（ｋ：変質層成長速度定数、ｋ０：定数、Ｑ：活性化エネルギー（ｋＪ／ｍоｌ）、Ｒ：気体定数（８．３１Ｊ／ｍоｌ・Ｋ）、Ｔ：温度（Ｋ））で表される。このアレニウスの式を対数の式で書き表すと、ｌｎｋ＝ｌｎｋ０−Ｑ／ＲＴとなる。そして、上述のようにして求めた変質層成長速度定数ｋ及び温度Ｔの関係を、縦軸にｌｎｋ、横軸に１／Ｔとして図示すれば、その傾きが−Ｑ／Ｒとなり、Ｑ及びｋ０の値を算出することができる。 Here, the altered layer growth rate constant k is the Arrhenius equation k = k 0 · exp (−Q / RT) (k: altered layer growth rate constant, k 0 : constant, Q: an equation representing the thermal activation process. Activation energy (kJ / mol), R: gas constant (8.31 J / mol · K), T: temperature (K)). When this Arrhenius equation is expressed by a logarithmic equation, lnk = lnk 0 −Q / RT. Then, if the relationship between the deteriorated layer growth rate constant k and the temperature T obtained as described above is illustrated with lnk on the vertical axis and 1 / T on the horizontal axis, the slope becomes −Q / R, and Q and k A value of 0 can be calculated.
変質層２０の厚さＤは、アレニウスの式を用いれば、Ｄ＝ｋ０・ｅｘｐ（−Ｑ／ＲＴ）・ｔ１／２（Ｄ：変質層の厚さ、ｋ０：定数、Ｑ：活性化エネルギー（ｋＪ／ｍоｌ）、Ｒ：気体定数（８．３１Ｊ／ｍоｌ・Ｋ）、Ｔ：温度（Ｋ）、ｔ：時間）のように表される。本実施形態では、上述のようにして、定数ｋ０、活性化エネルギーＱを算出し、変質層２０の厚さＤと、温度Ｔ及び時間ｔの関係を示す予測式（指標）を予め作成しておく構成とされている。 The thickness D of the altered layer 20 can be calculated by using the Arrhenius equation: D = k 0 · exp (−Q / RT) · t 1/2 (D: thickness of the altered layer, k 0 : constant, Q: activity Energy (kJ / mol), R: gas constant (8.31 J / mol · K), T: temperature (K), t: time). In the present embodiment, as described above, the constant k 0 and the activation energy Q are calculated, and a prediction formula (index) indicating the relationship between the thickness D of the altered layer 20, the temperature T, and the time t is created in advance. It is supposed to be configured.
（第二の工程）＜Ｓ２０＞
第二の工程Ｓ２０は、構造部材の表層に形成された変質層２０の厚さを測定する工程である。
本実施形態では、Ｎｉ基耐熱合金で構成されたタービンやジェットエンジン等の動静翼において、コーティング膜が形成されていない所定の位置からサンプルを採取し、変質層２０を測定する。構造部材の表層における断面組織の具体例として、図３にＳＥＭ（走査型電子顕微鏡）により観察された金属組織写真を示す。図３の（Ａ）は、初期状態（高温環境下に曝される前）の構造部材の断面組織写真、図３の（Ｂ）は、長時間構造部材が高温環境に曝された後の構造部材の断面組織写真である。
(Second step) <S20>
The second step S20 is a step of measuring the thickness of the altered layer 20 formed on the surface layer of the structural member.
In the present embodiment, a sample is taken from a predetermined position where a coating film is not formed in a moving and stationary blade such as a turbine or a jet engine made of a Ni-base heat-resistant alloy, and the altered layer 20 is measured. As a specific example of the cross-sectional structure in the surface layer of the structural member, FIG. 3 shows a metal structure photograph observed with an SEM (scanning electron microscope). 3A is a cross-sectional structure photograph of a structural member in an initial state (before being exposed to a high temperature environment), and FIG. 3B is a structure after the structural member has been exposed to a high temperature environment for a long time. It is a cross-sectional structure | tissue photograph of a member.
構造部材の初期状態は、図３（Ａ）で示されるように、内部から表層までγ’相が析出している（図３（Ａ）の矢印は最表層を示している）。これに対して、図３（Ｂ）で示されるように、長時間高温環境に曝された後の構造部材の内部にはγ’相が多数析出している（図３（Ｂ）の下方）が、表層には、γ’相が消失した変質層が形成されている。第二の工程Ｓ２０では、この変質層の厚さ（図２（Ｂ）の両矢印で示されている厚み）を測定する。 In the initial state of the structural member, as shown in FIG. 3A, a γ ′ phase is precipitated from the inside to the surface layer (the arrow in FIG. 3A indicates the outermost layer). On the other hand, as shown in FIG. 3B, a large number of γ ′ phases are precipitated inside the structural member after being exposed to a high temperature environment for a long time (below in FIG. 3B). However, an altered layer in which the γ ′ phase has disappeared is formed on the surface layer. In the second step S20, the thickness of the deteriorated layer (thickness indicated by a double arrow in FIG. 2B) is measured.
（第三の工程）＜Ｓ３０＞
第三の工程Ｓ３０は、第一の工程Ｓ１０と第一の工程Ｓ２０との関係を対応づけて構造部材の温度を算出する工程である。
第二の工程で測定したγ’相が消失した層（変質層２０）の厚さを、第一の工程で作成した変質層２０の厚さと温度及び時間の関係を示す指標に対応づけて構造部材の温度を算出する。具体的には、第二の工程で測定した変質層２０の厚さと構造部材が高温環境に曝された時間を、第一の工程で作成したＤ＝ｋ０・ｅｘｐ（−Ｑ／ＲＴ）・ｔ１／２に代入することにより、構造部材の温度Ｔを算出することができる。
本実施形態では、上述のようにして構造部材の温度を推定することができるようになっている。
(Third step) <S30>
The third step S30 is a step of calculating the temperature of the structural member by associating the relationship between the first step S10 and the first step S20.
The thickness of the layer (modified layer 20) from which the γ ′ phase disappeared measured in the second step is associated with an index indicating the relationship between the thickness of the modified layer 20 created in the first step, temperature, and time. Calculate the temperature of the member. Specifically, the thickness of the altered layer 20 measured in the second step and the time during which the structural member was exposed to the high temperature environment were determined as D = k 0 · exp (−Q / RT) · By substituting for t 1/2 , the temperature T of the structural member can be calculated.
In the present embodiment, the temperature of the structural member can be estimated as described above.
次に、具体例として測定を行った結果について説明する。
まず、構造部材に用いているＮｉ基耐熱合金と同様の組成のサンプルを用意し、保持温度及び各保持温度における保持時間を変えて熱処理を行った。ここでは、保持温度をａ１〜ａ６（８００Ｋ〜１３００Ｋ）の６条件、保持時間を１０００、３０００、６０００、１００００時間の４条件にて実施した。なお、保持温度は、ａ１＜ａ２＜ａ３＜ａ４＜ａ５＜ａ６、となっている。
Next, the results of measurement as a specific example will be described.
First, a sample having the same composition as that of the Ni-base heat-resistant alloy used for the structural member was prepared, and heat treatment was performed while changing the holding temperature and the holding time at each holding temperature. Here, the holding temperature was 6 conditions of a1 to a6 (800K to 1300K) and the holding time was 1000, 3000, 6000, and 10000 hours. The holding temperature is a1 <a2 <a3 <a4 <a5 <a6.
そして各サンプルの表層における断面観察を行い、変質層２０を測定する。このようにして、変質層２０の厚さと時間（ｈ１／２）の関係を図４に示す。各保持温度における変質層２０の厚さと時間の関係は図４の直線で示すように、直線近似をすることができる。この近似は、例えば、回帰分析等により適宜最適な方法を用いて行えば良い。 And the cross-sectional observation in the surface layer of each sample is performed, and the deteriorated layer 20 is measured. In this way, the relationship between the thickness of the altered layer 20 and time (h 1/2 ) is shown in FIG. The relationship between the thickness of the altered layer 20 and the time at each holding temperature can be approximated by a straight line as shown by the straight line in FIG. This approximation may be performed using an optimum method as appropriate by, for example, regression analysis.
次に、変質層成長速度定数ｋ及び活性化エネルギーＱを算出するために、縦軸にｌｎｋ、横軸に１／Ｋをとり、図５で示すように、図４の各直線の傾きをプロットする。そして各プロットに対して、図５の直線３０で示すように、直線近似を行い、傾き（−Ｑ／ＲＴ）を算出してＱ及びｋ０を決定する。なお、この近似は、例えば、回帰分析等により適宜最適な方法を用いて行えば良い。
このようにして、γ’相が消失した変質層２０の生成予測式（指標）を作成した（Ｓ１０）。
Next, in order to calculate the altered layer growth rate constant k and the activation energy Q, the vertical axis is lnk, the horizontal axis is 1 / K, and the slope of each straight line in FIG. 4 is plotted as shown in FIG. To do. Then, as shown by a straight line 30 in FIG. 5, linear approximation is performed on each plot, and a slope (−Q / RT) is calculated to determine Q and k 0 . This approximation may be performed using an optimal method as appropriate by, for example, regression analysis.
Thus, the production | generation prediction formula (index) of the deteriorated layer 20 from which the γ ′ phase disappeared was created (S10).
次に、本実施形態の温度の推定対象である高温環境に長時間曝された構造部材の所定の位置からサンプルを採取し、構造部材の表層における断面の組織観察を行い、変質層２０の厚さを測定した（Ｓ２０）。
そして、この変質層２０の厚さと構造部材が高温環境に曝された時間とを、上記の式に代入して構造部材の温度を算出する（Ｓ３０）。
Next, a sample is taken from a predetermined position of the structural member that has been exposed to a high-temperature environment, which is a temperature estimation target of the present embodiment, for a long period of time, and a cross-sectional structure observation is performed on the surface layer of the structural member. The thickness was measured (S20).
Then, the temperature of the structural member is calculated by substituting the thickness of the altered layer 20 and the time during which the structural member has been exposed to a high temperature environment into the above formula (S30).
構造部材の算出された温度と実験で求めた温度との対応関係を示したものを図６に示す。図６の縦軸には、上記のようにしてγ’相が消失した変質層２０から算出した構造部材の推定温度、横軸には実際に加熱した温度をとり、評価した２６点について図６にプロットしている。 FIG. 6 shows a correspondence relationship between the calculated temperature of the structural member and the temperature obtained by the experiment. The vertical axis of FIG. 6 represents the estimated temperature of the structural member calculated from the altered layer 20 from which the γ ′ phase has disappeared as described above, and the horizontal axis represents the actually heated temperature. Is plotted.
図６の直線４０は、各プロット点を近似したものであり、構造部材の変質層２０の厚さから推定した構造部材の温度と、実際に加熱した温度とは、良い一致を示していることが分かる。上述した方法を用いることにより、構造部材の温度を推定することができるようになっている。 A straight line 40 in FIG. 6 is an approximation of each plot point, and the temperature of the structural member estimated from the thickness of the altered layer 20 of the structural member shows a good agreement with the actually heated temperature. I understand. By using the method described above, the temperature of the structural member can be estimated.
本実施形態に係る構造部材の温度推定方法によれば、構造部材の変質層２０の厚さを、予め定めた変質層２０の厚さと温度及び時間の関係を示した予測式（指標）に対応させて構造部材の温度を推定する。変質層２０の厚さから予測式に基づいて温度を推定するので、広い温度範囲にわたって構造部材の温度を精度良く評価することが可能となる。そして、構造部材の温度を精度良く評価することにより、構造部材の保全を適切に行うことができ、構造部材の信頼性を向上させたり、メンテナンスにかかるコストを低減したりすることができる。例えば、ガスタービンの動翼を構成する構造部材の推定温度が、設計よりも高温と推定される場合には、早めに構造部材を交換することにより、ガスタービンの動翼が破損に至ることを予防することが可能である。 According to the temperature estimation method for a structural member according to the present embodiment, the thickness of the altered layer 20 of the structural member corresponds to a prediction formula (index) that indicates the relationship between the thickness of the altered layer 20 and the temperature and time. To estimate the temperature of the structural member. Since the temperature is estimated from the thickness of the altered layer 20 based on the prediction formula, the temperature of the structural member can be accurately evaluated over a wide temperature range. Then, by accurately evaluating the temperature of the structural member, the structural member can be properly maintained, the reliability of the structural member can be improved, and the cost for maintenance can be reduced. For example, if the estimated temperature of the structural members that make up the moving blades of the gas turbine is estimated to be higher than the design, replace the structural members early to prevent damage to the moving blades of the gas turbine. It is possible to prevent.
また、本実施形態では、変質層２０の厚さを測定する構成とされているので、構造部材の表層における断面観察を行いγ’相の固溶している領域と析出している領域の境界を判断することにより、変質層の厚さを容易かつ正確に把握することが可能である。 In the present embodiment, since the thickness of the altered layer 20 is measured, the cross-section of the surface layer of the structural member is observed, and the boundary between the solid solution region of the γ ′ phase and the deposited region is observed. By determining the above, it is possible to easily and accurately grasp the thickness of the deteriorated layer.
また、本実施形態では、Ｄ＝ｋ０・ｅｘｐ（−Ｑ／ＲＴ）・ｔ１／２（Ｄ：変質層の厚さ、Ｑ：活性化エネルギー、Ｔ：絶対温度、ｔ：時間、ｋ０：定数）で表される予測式に、構造部材の変質層２０の厚さを対応させて構造部材の温度を推定している。この予測式は、熱活性化過程を表すアレニウスの式に基づいて算出されているので、構造部材の温度の推定精度を向上させることができる。また、予測式に基づいて変質層２０の厚さから温度を推定するので容易に構造部材の温度を推定することが可能である。 In this embodiment, D = k 0 · exp (−Q / RT) · t 1/2 (D: thickness of the altered layer, Q: activation energy, T: absolute temperature, t: time, k 0 The temperature of the structural member is estimated by associating the thickness of the altered layer 20 of the structural member with the prediction formula expressed by: constant). Since this prediction equation is calculated based on the Arrhenius equation representing the thermal activation process, the estimation accuracy of the temperature of the structural member can be improved. Further, since the temperature is estimated from the thickness of the altered layer 20 based on the prediction formula, the temperature of the structural member can be easily estimated.
以上、本発明の一実施形態である、タービンやジェットエンジンの動静翼等に用いられるＮｉ基耐熱合金で構成された構造部材の温度推定方法について説明したが、本発明はこれに限定されることはなく、この発明の技術的思想を逸脱しない範囲で適宜変更可能である。 As mentioned above, although the temperature estimation method of the structural member comprised with the Ni-base heat-resistant alloy used for the moving blades and stationary blades of a turbine or a jet engine which is one embodiment of the present invention has been described, the present invention is limited to this. The present invention can be modified as appropriate without departing from the technical idea of the present invention.
上記実施の形態では、予め構造部材の変質層と温度及び時間の関係を示す指標を作成しておく構成について説明したが、この指標は構造部材が高温環境に置かれる前に作成しておく必要はなく、構造部材が高温環境に置かれている間や、高温環境に置かれた後に指標を作成する構成としても良い。 In the above-described embodiment, the configuration in which the index indicating the relationship between the deteriorated layer of the structural member and the temperature and time has been described in advance, but this index needs to be generated before the structural member is placed in a high temperature environment. Instead, the index may be created while the structural member is placed in a high temperature environment or after being placed in a high temperature environment.
また、上記実施の形態では、構造部材の変質層と温度及び時間の関係を示す指標が、Ｄ＝ｋ０・ｅｘｐ（−Ｑ／ＲＴ）・ｔ１／２（Ｄ：変質層の厚さ、Ｑ：活性化エネルギー、Ｔ：絶対温度、ｔ：時間、ｋ０：定数）で表される構成について説明したが、この指標に限定するものではなく、例えば、経験的に定めた構造部材の変質層と温度及び時間の関係等、変質層の厚さが温度及び時間の関係で表される指標であれば良い。 In the above embodiment, the index indicating the relationship between the altered layer of the structural member and the temperature and time is D = k 0 · exp (−Q / RT) · t 1/2 (D: thickness of the altered layer, The structure represented by Q: activation energy, T: absolute temperature, t: time, k 0 : constant) has been described. However, the structure is not limited to this index. Any index may be used as long as the thickness of the altered layer is represented by the relationship between temperature and time, such as the relationship between the layer and temperature and time.
また、上記実施の形態では、変質層は、酸化層とγ’相の固溶した層で構成される場合について説明したが、変質層はγ’相の固溶した層のみで構成されても良い。この場合においても、上述した方法と同様にして、構造部材の温度を推定することが可能である。 Further, in the above-described embodiment, the case where the altered layer is composed of an oxide layer and a layer in which the γ ′ phase is dissolved is described. However, the altered layer may be composed only of a layer in which the γ ′ phase is dissolved. good. Even in this case, the temperature of the structural member can be estimated in the same manner as described above.
２０ 変質層
２２ γ’相の固溶した層
20 Altered layer 22 γ ′ phase solid solution layer
Claims (4)
前記構造部材の表層のＡｌが空気中の酸素と結合して形成されたアルミナ及び該アルミナの形成による前記母材からの前記Ａｌの減少に伴って前記γ’相が前記母相に固溶した層からなる変質層の厚さと、温度及び時間の関係を示した指標を定め、
前記構造部材における前記変質層の厚さを測定し、該測定値を前記指標と対応させて、前記構造部材の温度を算出することを特徴とする構造部材の温度推定方法。 A temperature estimation method for estimating the temperature of a structural member composed of a Ni-base heat-resistant alloy having a parent phase and a γ ′ phase ,
The alumina formed by combining Al in the surface layer of the structural member with oxygen in the air, and the γ ′ phase dissolved in the matrix as the Al decreased from the matrix due to the formation of the alumina. Establishing an index showing the relationship between the thickness of the altered layer consisting of layers and the temperature and time,
A method for estimating the temperature of a structural member, comprising: measuring a thickness of the deteriorated layer in the structural member; and calculating a temperature of the structural member by associating the measured value with the index.
Ｄ：変質層の厚さ、Ｑ：活性化エネルギー、Ｔ：絶対温度、ｔ：時間、ｋ：速度定数
で表されることを特徴とする請求項１または請求項２に記載の構造部材の温度推定方法。 The index is D = k 0 · exp (−Q / RT) · t 1/2
The temperature of the structural member according to claim 1 or 2, wherein D: thickness of the altered layer, Q: activation energy, T: absolute temperature, t: time, k: rate constant Estimation method.
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