JP2011174894A - Embrittlement evaluation method for heat-resistant steel - Google Patents
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Abstract
Description
本発明は、耐熱鋼の脆化を評価する方法に関するものである。 The present invention relates to a method for evaluating embrittlement of heat resistant steel.
ガスタービンは高温環境で使用されるため、ローターなどの部材には、高Ｃｒ鋼のような耐熱鋼が用いられている。タービンを高温で長時間運転することにより、耐熱鋼ではクリープ、疲労、軟化、酸化や脆化などが生じる。そのため、定期的に点検や検査を行い、それら損傷が進んだ耐熱鋼を修理・交換するメンテナンスが必要となる。 Since the gas turbine is used in a high temperature environment, heat resistant steel such as high Cr steel is used for members such as a rotor. By operating the turbine at a high temperature for a long time, creep, fatigue, softening, oxidation, embrittlement, etc. occur in heat-resistant steel. For this reason, it is necessary to carry out regular inspections and inspections, and maintenance for repairing and replacing the damaged heat-resistant steel.
耐熱鋼の脆化のメカニズムの１つとして、焼き戻し脆化がある。焼き戻し脆化とは、Ｐ、Ｓｎ、Ａｓ、Ｓｂなどの脆化元素が結晶粒界に偏析し、粒界破壊しやすくなることによって生じる脆化である。この焼き戻し脆化は、従来、電気化学的方法（特許文献１及び特許文献２参照）、磁気的方法、超音波を利用した方法、アコースティック・エミッション法（ＡＥ計測法）、内部摩擦法などにより評価されている。また、腐食割れ等の経年的な変化を評価す方法の１つとして、硬さを測定する方法が用いられている（特許文献３参照）。
One of the mechanisms of embrittlement of heat resistant steel is temper embrittlement. Temper embrittlement is embrittlement that occurs when embrittlement elements such as P, Sn, As, and Sb segregate at the grain boundaries and are likely to break the grain boundaries. This temper embrittlement is conventionally performed by an electrochemical method (see
耐熱鋼は、高温環境下で使用すると、析出物が生成され、析出硬化する可能性があることが知られている。そのため、通常、使用前に耐熱鋼を熱処理して、予想される析出物を使用前に析出させて、組織を安定化させるという手法がとられている。しかし、使用中に析出が起きる場合、生成された析出物の量などから、耐熱鋼の寿命などを予測することができる。 When heat-resistant steel is used in a high temperature environment, it is known that precipitates are generated and precipitation hardening may occur. Therefore, usually, a heat-resistant steel is heat-treated before use, and a predicted precipitate is precipitated before use to stabilize the structure. However, when precipitation occurs during use, the life of the heat-resistant steel can be predicted from the amount of the generated precipitate.
しかしながら、析出硬化のメカニズムは、耐熱鋼の組成によって析出物の種類が異なるため、析出硬化の挙動（析出温度等）は耐熱鋼によって異なる。そのため、長時間使用した後に予期せぬ新たな析出物が生成されることもあるが、使用前に、このような使用途中で生成された析出物が耐熱鋼に及ぼす影響まで予測することは困難である。 However, the precipitation hardening mechanism varies depending on the composition of the heat-resistant steel, and therefore the behavior of precipitation hardening (precipitation temperature, etc.) differs depending on the heat-resistant steel. Therefore, unexpected new precipitates may be generated after long-term use, but it is difficult to predict the effect of such precipitates generated during use on heat resistant steel before use. It is.
本発明は、上記問題に鑑みなされたものであり、使用途中に析出物が生成された耐熱鋼の状態を評価する方法を提供することを目的とする。 This invention is made | formed in view of the said problem, and it aims at providing the method of evaluating the state of the heat resistant steel in which the precipitate was produced | generated in the middle of use.
上記問題を解決するために、本発明は、検査対象の耐熱鋼に生成した微細析出物を検出し、該検出した微細析出物の面積率を算出し、該算出した微細析出物の面積率の値を、予め作成された脆化指標と耐熱鋼に生成した微細析出物の面積率との相関を表すマスターカーブと照合して、前記算出した微細析出物の面積率に対する脆化指標を取得する耐熱鋼の脆化評価方法を提供する。 In order to solve the above problem, the present invention detects fine precipitates generated in the heat-resistant steel to be inspected, calculates the area ratio of the detected fine precipitates, and calculates the area ratio of the calculated fine precipitates. The value is collated with a master curve representing the correlation between the embrittlement index prepared in advance and the area ratio of the fine precipitates generated in the heat resistant steel, and the embrittlement index for the calculated area ratio of the fine precipitates is obtained. A method for evaluating embrittlement of heat resistant steel is provided.
本発明者らは、耐熱鋼を用いたガスタービンのローターにおいて、３００℃〜４５０℃の高温環境で長時間使用した後に、新たな微細析出物が生じることを発見し、且つ、この微細析出物の析出量が耐熱鋼の硬化をともなう脆化と相関していることを見出した。従って、検査対象の耐熱鋼に生成した微細析出物の面積率を算出し、予め作成されたマスターカーブと照合することで、耐熱鋼の脆化度合いを評価することができる。 The inventors of the present invention have discovered that a new fine precipitate is generated after a long time use in a high temperature environment of 300 ° C. to 450 ° C. in a gas turbine rotor using heat-resistant steel, and this fine precipitate It was found that the amount of precipitation was correlated with embrittlement accompanied by hardening of heat-resistant steel. Therefore, the degree of embrittlement of the heat-resistant steel can be evaluated by calculating the area ratio of fine precipitates generated in the heat-resistant steel to be inspected and comparing it with a master curve prepared in advance.
上記の微細析出物は、Ｍ２Ｘ型炭窒化物であり、大きさが１００ｎｍより小さく，更に４０ｎｍ未満であることが好ましい。
Ｍ２Ｘ型炭窒化物の析出量は、耐熱鋼の硬化をともう脆化と相関する。
耐熱鋼には、使用前に熱処理した際に、大きさが数百μｍ程度の別の析出物が生成される。Ｍ２Ｘ型炭窒化物の大きさが４０ｎｍ未満であれば、別の析出物と区別しやすいため、Ｍ２Ｘ型炭窒化物のみを検出することが容易となる。
The fine precipitate is an M 2 X-type carbonitride and preferably has a size smaller than 100 nm and further smaller than 40 nm.
The amount of precipitation of the M 2 X-type carbonitride correlates with the embrittlement of the heat-resistant steel.
When heat-treated steel is heat-treated before use, another precipitate having a size of about several hundred μm is generated. If the size of the M 2 X-type carbonitride is less than 40 nm, it is easy to distinguish from other precipitates, and therefore it becomes easy to detect only the M 2 X-type carbonitride.
上記の脆化指標は、延性脆性遷移温度とすることができる。脆化指標は、検査対象の使用前の延性脆性遷移温度と、検査対象の評価時の延性脆性遷移温度との差とすることが好ましい。
延性脆性遷移温度は、簡便な脆化評価手法であるシャルピー衝撃試験により得られるため、短時間で耐熱鋼の脆性の度合いを評価することが可能となる。
The embrittlement index may be a ductile brittle transition temperature. The embrittlement index is preferably the difference between the ductile brittle transition temperature before use of the test object and the ductile brittle transition temperature at the time of evaluation of the test object.
Since the ductile brittle transition temperature is obtained by a Charpy impact test, which is a simple brittleness evaluation method, the degree of brittleness of the heat-resistant steel can be evaluated in a short time.
上記発明において、前記検査対象の耐熱鋼の硬さ変化量を計測し、該計測した硬さ変化量を、予め作成された脆化指標と耐熱鋼の硬さ変化量との相関を表すマスターカーブと照合して、前記計測した硬さ変化量に対する脆化指標を読み取り、該読み取った脆化指標を、前記微細析出物の面積率に対する脆化指標と合算して平均値を取得することが好ましい。
上記の微細析出物は、耐熱鋼の硬化をともなう脆化と相関しているため、耐熱鋼の硬さと合わせて評価することで、評価精度を向上させることができる。
In the above invention, a master curve representing a correlation between a preliminarily created embrittlement index and a hardness change amount of the heat-resistant steel, by measuring a hardness change amount of the heat-resistant steel to be inspected. It is preferable to read the embrittlement index with respect to the measured hardness change amount, and add the read embrittlement index with the embrittlement index with respect to the area ratio of the fine precipitates to obtain an average value. .
Since the fine precipitates described above correlate with embrittlement accompanied by hardening of the heat resistant steel, the evaluation accuracy can be improved by evaluating together with the hardness of the heat resistant steel.
本発明によれば、硬化をともなって耐熱鋼を脆化させる析出物が使用途中に生成された耐熱鋼の脆化を非破壊で評価することができる。 According to the present invention, it is possible to evaluate non-destructively the embrittlement of a heat-resistant steel in which precipitates that embrittle the heat-resistant steel with hardening are generated during use.
３００℃〜４５０℃の高温環境で長時間使用した後に微細析出物が生成される耐熱鋼としては、高Ｃｒ鋼、例えば、１０Ｃｒ−６Ｃｏ鋼が挙げられる。このような高Ｃｒ鋼は、多くの元素を含有しているために、長時間使用すると、微細析出物が析出する場合がある。 Examples of the heat resistant steel in which fine precipitates are generated after use for a long time in a high temperature environment of 300 ° C. to 450 ° C. include high Cr steel, for example, 10Cr-6Co steel. Since such high Cr steel contains many elements, fine precipitates may precipitate when used for a long time.
図１に、使用途中に耐熱鋼に生成された微細析出物の電子顕微鏡写真を示す。図１（ａ）は使用前に熱処理を施した耐熱鋼である。図１（ｂ）は３００℃〜４５０℃の高温環境下で、１５万時間程度使用した後の耐熱鋼である。図１（ｃ）及び図１（ｄ）は、図１（ａ）及び図１（ｂ）の一部を拡大した写真である。図１（ａ）では、粗大な析出物１が観察された。一方、図１（ｂ）では、粗大な析出物１とともに、新たに別の微細な析出物２が観察された。
図１（ａ）及び図１（ｂ）の耐熱鋼の硬さを測定したところ、１５万時間程度使用した後の耐熱鋼の硬さは、使用前よりも５０ＨＶ程度増加していた。
In FIG. 1, the electron micrograph of the fine precipitate produced | generated on the heat resistant steel in the middle of use is shown. FIG. 1 (a) shows a heat-resistant steel that has been heat-treated before use. FIG. 1 (b) shows the heat resistant steel after being used for about 150,000 hours in a high temperature environment of 300 ° C. to 450 ° C. FIG.1 (c) and FIG.1 (d) are the photographs which expanded a part of FIG.1 (a) and FIG.1 (b). In FIG. 1 (a),
When the hardness of the heat resistant steel shown in FIGS. 1 (a) and 1 (b) was measured, the hardness of the heat resistant steel after about 150,000 hours of use was increased by about 50 HV than before use.
微細析出物は、一般式Ｍ２Ｘ（Ｍ：Ｃｒ、Ｆｅ、Ｍｏ等、Ｘ：Ｃ、Ｎ）で表される炭窒化物であることを確認した。この微細析出物は、大きさが４０ｎｍ未満であって、主に３００℃〜４５０℃で長時間使用された耐熱鋼に生成される。 The fine precipitate was confirmed to be a carbonitride represented by the general formula M 2 X (M: Cr, Fe, Mo, etc., X: C, N). This fine precipitate is produced in heat-resistant steel having a size of less than 40 nm and mainly used at 300 ° C. to 450 ° C. for a long time.
〔第１実施形態〕
以下、本発明の第１実施形態について説明する。
本実施形態に係る耐熱鋼の脆化評価方法は、マスターカーブ作成工程と、検査工程と、評価工程とを備えている。
[First Embodiment]
The first embodiment of the present invention will be described below.
The heat-resistant steel embrittlement evaluation method according to the present embodiment includes a master curve creation step, an inspection step, and an evaluation step.
マスターカーブ作成工程では、脆化指標と微細析出物の面積率とを相関させてマスターカーブを作成する。
具体的には、まず、耐熱鋼を３００〜４５０℃で最大１５万時間まで使用された様々な脆化度合いの試験片を準備する。次に、準備した試験片の脆化指標および微細析出物の面積率を算出する。
In the master curve creation step, a master curve is created by correlating the embrittlement index and the area ratio of fine precipitates.
Specifically, first, test pieces having various degrees of embrittlement using heat-resistant steel at 300 to 450 ° C. for a maximum of 150,000 hours are prepared. Next, the embrittlement index of the prepared test piece and the area ratio of fine precipitates are calculated.
脆化は、例えば、シャルピー衝撃試験によって測定することができる。本実施形態では、シャルピー衝撃試験で得られた延性脆性破面率が５０％になる温度の使用前からの変化量（以下「ΔＦＡＴＴ」と称する）を脆化指標とする。 The embrittlement can be measured by, for example, a Charpy impact test. In the present embodiment, the amount of change from before use (hereinafter referred to as “ΔFATT”) at which the ductile brittle fracture surface ratio obtained by the Charpy impact test becomes 50% is used as the brittleness index.
検査対象となる耐熱鋼表面の微細析出物の面積率は、例えば、ＴＥＭレプリカ法によって測定することができる。レプリカ法を用いる場合、エッチングの状態が気温などの周辺環境に影響されるため、検査対象物から直接レプリカを採取すると、レプリカに採取される微細析出物量が変化し、定量精度が低下してしまう。そのため、検査対象となる耐熱鋼表面から微小のサンプルを削り取るなどして採取し、そのサンプルを用いてレプリカを採取することが好ましい。 The area ratio of fine precipitates on the surface of the heat-resistant steel to be inspected can be measured by, for example, the TEM replica method. When the replica method is used, the etching state is affected by the surrounding environment such as the temperature. Therefore, if a replica is collected directly from the inspection object, the amount of fine precipitates collected in the replica changes, resulting in a decrease in quantitative accuracy. . For this reason, it is preferable to collect a small sample from the surface of the heat-resistant steel to be inspected, for example, and collect a replica using the sample.
採取したサンプルは、エッチング液にてエッチングし、アセチルセルロース等のレプリカフィルムに転写してレプリカを採取する。エッチング条件（時間、温度等）は、適宜選定する。エッチング時間は、長すぎると微細析出物が定着し難くなるが、短すぎるとエッチング不足により微細析出物が現出しない。また、エッチング温度が低いと、エッチング時間が同じであっても、よりエッチング時間を長くしないと微細析出物が現出しない。このように、エッチング条件は、得られる微細析出物量に影響する。従って、エッチングによる計測のばらつきを小さくするために、エッチング標準サンプルを用いて、電子顕微鏡等でエッチング状態を確認することが好ましい。そうすることにより、ΔＦＡＴＴの推定精度を向上させることができる。 The collected sample is etched with an etching solution and transferred to a replica film such as acetylcellulose to collect a replica. Etching conditions (time, temperature, etc.) are appropriately selected. If the etching time is too long, fine precipitates are difficult to fix, but if it is too short, fine precipitates do not appear due to insufficient etching. Moreover, if the etching temperature is low, even if the etching time is the same, fine precipitates will not appear unless the etching time is increased. Thus, etching conditions influence the amount of fine precipitates obtained. Therefore, in order to reduce measurement variations due to etching, it is preferable to check the etching state with an electron microscope or the like using an etching standard sample. By doing so, the estimation accuracy of ΔFATT can be improved.
例えば、本発明者らは、エッチング液やエッチング時間は所定の条件とし、エッチング時間を９０秒、１２０秒、１５０秒、１８０秒、２４０秒と変化させて試験片を作製した。エッチング時間を１８０秒とした試験片において、微細析出物の定着が最適となることを電子顕微鏡にて確認した。この場合、所定の観察倍率で、この１８０秒の試験片の析出物の電子顕微鏡写真を撮影し、エッチングの標準条件とすることができる。 For example, the present inventors made test pieces by changing the etching time and the etching time to 90 seconds, 120 seconds, 150 seconds, 180 seconds, and 240 seconds under predetermined conditions. In the test piece with an etching time of 180 seconds, it was confirmed with an electron microscope that the fine precipitates were optimally fixed. In this case, an electron micrograph of the 180-second test piece deposit can be taken at a predetermined observation magnification to obtain the standard etching conditions.
上記のように採取したレプリカを透過型電子顕微鏡にて観察し、所定の観察倍率における一定視野に対する微細析出物の面積の割合を面積率として算出する。 The replica collected as described above is observed with a transmission electron microscope, and the ratio of the area of fine precipitates to a fixed visual field at a predetermined observation magnification is calculated as an area ratio.
次に、上記で得られた脆化指標および微細析出物の面積率を用いて、マスターカーブを作成する。作成したマスターカーブは、相関係数が０．７以上のものを採用とする。図２に、脆化指標と微細析出物の面積率とを相関させたマスターカーブの一例を示す。同図において、横軸を微細析出物の面積率、縦軸を脆化指標（ΔＦＡＴＴ）とする。 Next, a master curve is created using the embrittlement index obtained above and the area ratio of fine precipitates. The created master curve has a correlation coefficient of 0.7 or more. FIG. 2 shows an example of a master curve in which the embrittlement index and the area ratio of fine precipitates are correlated. In the figure, the horizontal axis represents the area ratio of fine precipitates, and the vertical axis represents the embrittlement index (ΔFATT).
検査工程では、マスターカーブ作成工程と同様に、検査対象の耐熱鋼の調査位置から微小のサンプルを採取して、そのサンプルからレプリカを採取する。そうすることで、微細析出物の定量精度が向上するだけでなく、再試も可能となる。
採取したレプリカを透過型電子顕微鏡にて所定倍率で観察し、微細析出物の面積率を算出する。
In the inspection process, as in the master curve creation process, a small sample is collected from the investigation position of the heat-resistant steel to be inspected, and a replica is collected from the sample. By doing so, not only the quantitative accuracy of fine precipitates is improved, but also retrial is possible.
The collected replica is observed with a transmission electron microscope at a predetermined magnification, and the area ratio of fine precipitates is calculated.
評価工程では、検査工程で得られた微細析出物の面積率の値と、マスターカーブとを照合し、その面積率に対するΔＦＡＴＴの値を読み取る。このΔＦＡＴＴの値を、検査対象の耐熱鋼の脆化度合いとし、耐熱鋼の脆化を評価する。
例えば、微細析出物の面積率が５０％であった場合、この値を図２のマスターカーブに挿入すると、ΔＦＡＴＴは１１２℃であることが読み取れる。
In the evaluation process, the area ratio value of the fine precipitates obtained in the inspection process is compared with the master curve, and the value of ΔFATT with respect to the area ratio is read. The value of ΔFATT is used as the degree of embrittlement of the heat resistant steel to be inspected, and the embrittlement of the heat resistant steel is evaluated.
For example, when the area ratio of fine precipitates is 50%, when this value is inserted into the master curve of FIG. 2, it can be read that ΔFATT is 112 ° C.
〔第２実施形態〕
本実施形態では、脆化指標と微細析出物の面積率とを相関させたマスターカーブの他に、脆化指標と耐熱鋼の硬さ変化量とを相関させた別のマスターカーブを作成して耐熱鋼の脆化を評価する。
[Second Embodiment]
In this embodiment, in addition to the master curve that correlates the embrittlement index and the area ratio of fine precipitates, another master curve that correlates the embrittlement index and the hardness change of the heat-resistant steel is created. Evaluate embrittlement of heat-resistant steel.
マスターカーブ作成工程では、脆化指標と微細析出物の面積率とを相関させたマスターカーブ（以下「第１マスターカーブ」と称する。）と、脆化指標と耐熱鋼の硬さ変化量とを相関させた別のマスターカーブ（以下「第２マスターカーブ」と称する。）と、を作成する。
試験片は、第１実施形態と同様に準備する。試験片の脆化指標と、微細析出物の面積率と硬さ変化量とをそれぞれ測定する。第１マスターカーブの作成方法は、第１実施形態と同様とする。
硬さは、例えば、市販のポータブルビッカース硬度計を使用して非破壊硬さを測定する。上記で得られた試験片の脆化指標の値と硬さ変化量の値を用いて、マスターカーブを作成する。
In the master curve creation step, a master curve (hereinafter referred to as “first master curve”) in which the embrittlement index and the area ratio of the fine precipitates are correlated, and the embrittlement index and the hardness change amount of the heat-resistant steel are obtained. Another correlated master curve (hereinafter referred to as “second master curve”) is created.
The test piece is prepared in the same manner as in the first embodiment. The embrittlement index of the test piece, the area ratio of fine precipitates, and the amount of change in hardness are measured. The method for creating the first master curve is the same as in the first embodiment.
For the hardness, for example, a non-destructive hardness is measured using a commercially available portable Vickers hardness tester. A master curve is created using the embrittlement index value and the hardness change value of the test piece obtained above.
図３に、脆化指標と耐熱鋼の硬さ変化量とを相関させた第２マスターカーブの一例を示す。同図において、横軸を硬さ変化量、縦軸を脆化指標（ΔＦＡＴＴ）とする。 FIG. 3 shows an example of the second master curve in which the embrittlement index and the hardness change amount of the heat resistant steel are correlated. In the figure, the horizontal axis is the amount of change in hardness, and the vertical axis is the embrittlement index (ΔFATT).
検査工程では、まず、検査対象の耐熱鋼の調査位置の硬さ変化量をマスターカーブ作成工程と同様の方法にて測定する。次に、同位置からマスターカーブ作成工程と同様の方法にて微小のサンプルを採取して、そのサンプルからレプリカを採取する。
採取したレプリカを透過型電子顕微鏡にて所定倍率で観察し、微細析出物の面積率を算出する。
In the inspection process, first, the amount of change in hardness at the inspection position of the heat-resistant steel to be inspected is measured by the same method as in the master curve creation process. Next, a minute sample is collected from the same position by the same method as the master curve creating step, and a replica is collected from the sample.
The collected replica is observed with a transmission electron microscope at a predetermined magnification, and the area ratio of fine precipitates is calculated.
評価工程では、検査工程で得られた微細析出物の面積率の値及び耐熱鋼の硬さ変化量を、それぞれ第１マスターカーブ及び第２マスターカーブと照合し、その面積率及び硬さ変化量に対するΔＦＡＴＴの値を読み取る。第１マスターカーブと第２マスターカーブから読み取った値を平均化し、得られたΔＦＡＴＴの値を、検査対象の耐熱鋼の脆化度合いとして、耐熱鋼の脆化を評価する。
例えば、微細析出物の面積率が５０％、硬さ変化量が３０ＨＶであった場合、これらの値を第１マスターカーブ及び第２マスターカーブ（図２及び図３）に挿入すると、それぞれのΔＦＡＴＴは１１２℃、１２９℃であることが読み取れる。上記結果から、この耐熱鋼のΔＦＡＴＴは１２１℃となる。
In the evaluation process, the area ratio value of the fine precipitate obtained in the inspection process and the hardness change amount of the heat-resistant steel are collated with the first master curve and the second master curve, respectively, and the area ratio and the hardness change amount thereof. Read the value of ΔFATT for. The values read from the first master curve and the second master curve are averaged, and the obtained ΔFATT value is used as the degree of embrittlement of the heat resistant steel to be inspected to evaluate the embrittlement of the heat resistant steel.
For example, when the area ratio of fine precipitates is 50% and the amount of change in hardness is 30 HV, when these values are inserted into the first master curve and the second master curve (FIGS. 2 and 3), each ΔFATT Is 112 ° C. and 129 ° C. From the above results, ΔFATT of this heat resistant steel is 121 ° C.
硬さは、ビッカース硬度計などの携帯式測定器を用いることで、現場で実機の硬さを測定できる利点を有する。しかしながら、硬度の測定値のばらつきがあるため、ΔＦＡＴＴの推定精度が低くなる可能性がある。また、実機の脆化を評価するには、実機の運転を停止させなくてはならない上、再度同じ場所を測定することは困難である。本実施形態では、第１マスターカーブと第２マスターカーブの２つのマスターカーブを用いることで、ＦＡＴＴの推定精度を向上させることができる。なお、第２マスターカーブから得られたΔＦＡＴＴの値が第１マスターカーブから得られたΔＦＡＴＴの値とかけ離れている場合、第１マスターカーブから読み取ったΔＦＡＴＴの値のみを用いて脆化を評価することもできる。 Hardness has an advantage that the hardness of an actual machine can be measured on site by using a portable measuring instrument such as a Vickers hardness tester. However, there is a possibility that the estimation accuracy of ΔFATT may be lowered due to variations in hardness measurement values. Moreover, in order to evaluate the embrittlement of the actual machine, it is necessary to stop the operation of the actual machine and it is difficult to measure the same place again. In the present embodiment, the FATT estimation accuracy can be improved by using two master curves of the first master curve and the second master curve. When the ΔFATT value obtained from the second master curve is far from the ΔFATT value obtained from the first master curve, the embrittlement is evaluated using only the ΔFATT value read from the first master curve. You can also.
なお、本発明は、上記実施形態に限定されるものではない。上記実施形態は例示であり、本発明の特許請求の範囲に記載された技術的思想と実質的に同一な構成を有し、同様な作用効果を奏するものは、いかなるものであっても本発明の技術的範囲に包含される。 The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.
１ 粗大析出物
２ 微細析出物
1 Coarse precipitate 2 Fine precipitate
Claims (4)
該検出した微細析出物の面積率を算出し、
該算出した微細析出物の面積率の値を、予め作成された脆化指標と耐熱鋼に生成した微細析出物の面積率との相関を表すマスターカーブと照合して、前記算出した微細析出物の面積率に対する脆化指標を取得する耐熱鋼の脆化評価方法。 Detects fine precipitates generated in the heat-resistant steel to be inspected,
Calculate the area ratio of the detected fine precipitates,
The calculated fine precipitate area value is collated with a master curve representing the correlation between the embrittlement index prepared in advance and the fine precipitate area ratio generated in the heat-resistant steel, and the calculated fine precipitate value is The embrittlement evaluation method of heat-resistant steel which acquires the embrittlement index | exponent with respect to the area ratio.
該計測した硬さ変化量を、予め作成された脆化指標と耐熱鋼の硬さ変化量との相関を表すマスターカーブと照合して、前記計測した硬さ変化量に対する脆化指標を読み取り、
該読み取った脆化指標を、前記微細析出物の面積率に対する脆化指標と合算して平均値を取得する請求項１乃至請求項３のいずれかに記載の耐熱鋼の脆化評価方法。 Measure the amount of change in hardness of the heat-resistant steel to be inspected,
The measured change in hardness is collated with a master curve representing a correlation between the embrittlement index prepared in advance and the hardness change in heat-resistant steel, and the embrittlement index with respect to the measured change in hardness is read.
The embrittlement evaluation method for heat-resistant steel according to any one of claims 1 to 3, wherein the read embrittlement index is added to the embrittlement index for the area ratio of the fine precipitates to obtain an average value.
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