JP2009036670A - Working temperature estimating method of austenitic steel - Google Patents

Working temperature estimating method of austenitic steel Download PDF

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JP2009036670A
JP2009036670A JP2007202043A JP2007202043A JP2009036670A JP 2009036670 A JP2009036670 A JP 2009036670A JP 2007202043 A JP2007202043 A JP 2007202043A JP 2007202043 A JP2007202043 A JP 2007202043A JP 2009036670 A JP2009036670 A JP 2009036670A
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steel pipe
hardened layer
stainless steel
temperature
hardness
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JP4968734B2 (en
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Masaru Shimizu
大 清水
Motoroku Nakao
元六 仲尾
Yuji Fukuda
祐治 福田
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Mitsubishi Power Ltd
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Babcock Hitachi KK
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a versatile and conventional technique capable of estimating a surface temperature of an austenitic heat-resistant steel pipe. <P>SOLUTION: In a method for estimating an actual working temperature of the austenitic stainless steel pipe used for a power generating boiler, a hardened layer is formed on a surface of a test piece by a cold working process. A relationship between a hardness of the hardened layer shown in Fig. 5 and a LMP (a Larson-Miller parameter) expressed by a function of an operating time and the operating temperature is previously obtained. After the hardened layer is formed on an outer surface or an inner surface of the austenitic stainless steel pipe before it is actually used, the hardness of the hardened layer actually used at a high temperature is measured. The actual operating temperature of the austenitic stainless steel pipe is estimated from the previously-obtained hardness of the hardened layer and a relational expression between the operating time and the LMP. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、火力発電用ボイラやゴミ焼却ボイラの高温部に使用されるオーステナイト系耐熱鋼のメタル温度の測定方法に関する。   The present invention relates to a method for measuring a metal temperature of an austenitic heat-resistant steel used in a high-temperature part of a thermal power generation boiler or a garbage incineration boiler.

近年、火力発電用大型ボイラにおいては、経済性の向上、ＣＯ２ガス排出抑制の観点から、プラント効率を向上させるために蒸気条件が高温高圧化する傾向にあり、材料の使用条件が一層厳しくなってきている。このような背景の下、高温強度と耐食性を向上させたボイラ用耐熱鋼が開発、実用化された。近年は、フェライト系の材料としてはＣｒ含有量８〜１２％の耐熱鋼、またオーステナイト系の材料としてはＣｒ含有量１８〜２５％の耐熱鋼が使用されている。これらの耐熱鋼の中から高温となる過熱器管及び再熱器管への適用の検討及び選定は、メタル温度や石炭性状等に基づき、クリープ寿命や腐食量評価によりなされているが、評価に用いられるメタル温度は過去の実績データや解析で求めた値ベースとなっている。しかしながら、設計メタル温度と実メタル温度がどの程度適合しているかの確認は、稼動中のボイラ炉内で多数の管のメタル温度を簡単に計測する方法がないため、非常に困難であった。このため、クリープや腐食による余寿命診断を高精度に行うためには、実メタル温度を高精度に評価する必要があった。 In recent years, large-scale boilers for thermal power generation tend to increase the steam conditions at high temperature and high pressure in order to improve plant efficiency from the viewpoint of improving economic efficiency and suppressing CO 2 gas emission, and the use conditions of materials have become more severe. It is coming. Against this background, heat-resistant steel for boilers with improved high-temperature strength and corrosion resistance has been developed and put to practical use. In recent years, heat-resistant steel having a Cr content of 8 to 12% is used as a ferrite material, and heat-resistant steel having a Cr content of 18 to 25% is used as an austenitic material. Examination and selection of application to superheater pipes and reheater pipes that become high temperature from among these heat resistant steels has been made based on the evaluation of creep life and corrosion amount based on metal temperature and coal properties. The metal temperature used is based on values obtained from past performance data and analysis. However, it is very difficult to confirm how much the design metal temperature and the actual metal temperature are compatible because there is no simple method for measuring the metal temperature of a large number of tubes in an operating boiler furnace. For this reason, in order to perform the remaining life diagnosis due to creep or corrosion with high accuracy, it is necessary to evaluate the actual metal temperature with high accuracy.

この課題を解決するため、特許文献１〜特許文献３に示す使用中のメタル温度を推定する方法が提案されている。
特開２００４−１１６８１０号公報 特開２００６−３００６０１号公報 特開２００３−３４４２６１号公報 In order to solve this problem, methods for estimating a metal temperature in use shown in Patent Documents 1 to 3 have been proposed.
JP 2004-116810 A JP 2006-300601 A JP 2003-344261 A

特許文献１（特開２００４−１１６８１０号公報）では、伝熱管パネルの異常なメタル温度を簡便かつ低コストに検知する方法が提案されているが、排熱回収ボイラの吊り下げ型伝熱管という特定装置・部位を対象としており、汎用性がない。また、特許文献２（特開２００６−３００６０１号公報）では、使用後の鋼材に析出した析出物の含有率変化を利用して、使用温度を推定する方法が提案されているが、析出物の含有率を測定するために、析出物のみをＩＣＰ発光分析およびＸ線回折分析により同定及び定量する方法を用いるので、使用中のメタル温度を推定する方法が簡便でない。   Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-116810) proposes a method for detecting an abnormal metal temperature of a heat transfer tube panel simply and at low cost, but it is specified as a suspended heat transfer tube of an exhaust heat recovery boiler. It is intended for devices and parts and is not versatile. Moreover, in patent document 2 (Unexamined-Japanese-Patent No. 2006-300601), although the method of estimating use temperature is proposed using the content rate change of the deposit deposited on the steel material after use, In order to measure the content rate, a method of identifying and quantifying only the precipitate by ICP emission analysis and X-ray diffraction analysis is used, so that the method of estimating the metal temperature in use is not simple.

汎用性かつ簡便な温度推定手法としては、材料の硬さ変化を利用する方法があり、特許文献３（特開２００３−３４４２６１号公報）では、フェライト系耐熱鋼の時効による硬さ変化を利用した温度推定方法が考案されている。しかし、この手法は温度、時間と共に硬さが単調に低下するフェライト系耐熱鋼には適用できるが、オーステナイト系耐熱鋼の場合には、材料強度を高めるために添加している合金成分の析出等により、使用温度や材質によっては一旦硬さが増加し、その後低下する挙動を示すことがあり、適用できなかった。従って、オーステナイト系耐熱鋼のメタル温度を幅広く簡便に推定する有効な手段はないのが現状である。   As a versatile and simple temperature estimation method, there is a method that uses a change in hardness of a material. In Patent Document 3 (Japanese Patent Laid-Open No. 2003-344261), a change in hardness due to aging of a ferritic heat resistant steel is used. A temperature estimation method has been devised. However, this method can be applied to ferritic heat resistant steels whose hardness decreases monotonically with temperature and time, but in the case of austenitic heat resistant steels, precipitation of alloy components added to increase material strength, etc. Therefore, depending on the operating temperature and material, the hardness once increased and then decreased, and could not be applied. Accordingly, there is currently no effective means for estimating the metal temperature of austenitic heat-resistant steel widely and simply.

本発明の課題は、上述した従来技術の問題を解決し、汎用性のある簡便なオーステナイト系耐熱鋼管の表面温度を推定できる手法を提供することにある。   An object of the present invention is to solve the above-described problems of the prior art and to provide a technique capable of estimating the surface temperature of a versatile and simple austenitic heat-resistant steel pipe.

本発明の上記課題は、以下に示す解決手段により達成される。
請求項１記載の発明は、発電用ボイラステンレス鋼管に用いられるオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法において、試験片の表面に冷間加工処理により硬化層を形成させ、該硬化層の硬さと、使用時間と使用温度との関数で表されるＬＭＰ（ラーソンミラーパラメータ）との関係を予め求めておき、次に実際に使用する前のオーステナイト系ステンレス鋼管の外表面に冷間加工処理により硬化層を形成させた後に、実際に高温で使用した当該硬化層の硬さを測定し、前記予め求めていた硬化層の硬さと、使用時間とＬＭＰとの関係式から当該オーステナイト系ステンレス鋼管の実際の使用温度を推定するオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法である。 The above-described problems of the present invention can be achieved by the following solution means.
The invention according to claim 1 is a method for estimating an actual operating temperature of an austenitic stainless steel pipe used for a boiler stainless steel pipe for power generation, wherein a hardened layer is formed on the surface of a test piece by cold working, and the hardened layer The relationship between the hardness of the steel and the LMP (Larson Miller parameter) expressed as a function of the use time and the use temperature is obtained in advance, and the outer surface of the austenitic stainless steel pipe before the next actual use is cold worked. After forming a hardened layer by treatment, the hardness of the hardened layer actually used at high temperature is measured, and the austenitic stainless steel is obtained from the relational expression between the hardness of the hardened layer obtained in advance and the use time and LMP. This is a method for estimating the actual use temperature of an austenitic stainless steel pipe for estimating the actual use temperature of the steel pipe.

請求項２記載の発明は、前記実際に使用する前のオーステナイト系ステンレス鋼管の外表面に形成した硬化層の表面に保護カバーを設けた請求項１記載のオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法である。   The invention according to claim 2 is the actual use temperature of the austenitic stainless steel pipe according to claim 1, wherein a protective cover is provided on the surface of the hardened layer formed on the outer surface of the austenitic stainless steel pipe before the actual use. This is an estimation method.

請求項３記載の発明は、前記実際に使用する前のオーステナイト系ステンレス鋼管の外表面に形成した硬化層の表面に保護皮膜からなる被覆部を設けた請求項１記載のオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法である。   The invention according to claim 3 is the actual state of the austenitic stainless steel pipe according to claim 1, wherein a covering portion made of a protective film is provided on the surface of the hardened layer formed on the outer surface of the austenitic stainless steel pipe before the actual use. It is a method of estimating the operating temperature of the.

請求項４記載の発明は、発電用ボイラステンレス鋼管に用いられるオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法において、試験片の表面に冷間加工処理により硬化層を形成させ、該硬化層の硬さと、使用時間と使用温度との関数で表されるＬＭＰ（ラーソンミラーパラメータ）との関係を予め求めておき、次に実際に使用する前のオーステナイト系ステンレス鋼管の内表面に冷間加工処理により硬化層を形成させた後に、実際に高温で使用した当該硬化層の硬さを測定し、前記予め求めていた硬化層の硬さと、使用時間とＬＭＰとの関係式から当該オーステナイト系ステンレス鋼管の実際の使用温度を推定するオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法である。   The invention according to claim 4 is a method for estimating an actual operating temperature of an austenitic stainless steel pipe used for a boiler stainless steel pipe for power generation, wherein a hardened layer is formed on the surface of a test piece by cold working, and the hardened layer The relationship between the hardness of the steel and the LMP (Larson Miller parameter) expressed as a function of the use time and the use temperature is obtained in advance, and cold working is then performed on the inner surface of the austenitic stainless steel pipe before actual use. After forming a hardened layer by treatment, the hardness of the hardened layer actually used at high temperature is measured, and the austenitic stainless steel is obtained from the relational expression between the hardness of the hardened layer obtained in advance and the use time and LMP. This is a method for estimating the actual use temperature of an austenitic stainless steel pipe for estimating the actual use temperature of the steel pipe.

請求項５記載の発明は、発電用ボイラステンレス鋼管に用いられるオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法において、試験片の表面に冷間加工処理により硬化層を形成させて該硬化層の硬さと、使用時間と使用温度との関数で表されるＬＭＰ（ラーソンミラーパラメータ）との関係を予め求めておき、次に既運転中のオーステナイト系ステンレス鋼管の外表面または内表面に冷間加工処理により硬化層を形成させた後に、さらに再運転後に実際に高温で使用した当該硬化層の硬さを測定し、前記予め求めていた硬化層の硬さと使用時間とＬＭＰ（ラーソンミラーパラメータ）との関係式から当該オーステナイト系ステンレス鋼管の実際の使用温度を推定するオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法である。   The invention according to claim 5 is a method for estimating an actual operating temperature of an austenitic stainless steel pipe used for a boiler stainless steel pipe for power generation, wherein the hardened layer is formed by forming a hardened layer on the surface of a test piece by cold working. The relationship between the hardness of the steel and the LMP (Larson Miller parameter) expressed as a function of the use time and the use temperature is obtained in advance, and then cold is applied to the outer surface or inner surface of the already operated austenitic stainless steel pipe. After forming a hardened layer by processing, the hardness of the hardened layer actually used at a high temperature after re-operation is measured, and the hardness and operating time of the hardened layer determined in advance and LMP (Larsson mirror parameters) Estimate the actual working temperature of the austenitic stainless steel pipe from the relational expression It is that way.

上記請求項１、４、５記載の発明において、オーステナイト系耐熱鋼の冷間加工処理による硬化層の硬さ上昇は、合金成分の析出等による硬さの変化分に比べると十分大きいため、硬さ変化を利用する温度推定が可能となる。   In the first, fourth, and fifth aspects of the present invention, the hardness increase of the hardened layer due to the cold working of the austenitic heat-resistant steel is sufficiently larger than the change in hardness due to precipitation of alloy components, etc. The temperature can be estimated using the change in height.

また、上記請求項２、３記載の発明のように、高硫黄含有量の重油焚きボイラ又は石炭焚きボイラでは高温腐食性が高く、管外面へのショットなどの冷間加工処理層が、運転中腐食減肉によって消失する可能性がある場合は、硬化層の上に耐食カバーを設ける。   In addition, as in the inventions of claims 2 and 3, high-temperature corrosiveness is high in a heavy oil fired boiler or coal fired boiler having a high sulfur content, and a cold processing layer such as a shot on the pipe outer surface is in operation. If there is a possibility of loss due to corrosion thinning, a corrosion-resistant cover is provided on the hardened layer.

上記請求項５記載の発明のように、既設運転中のボイラにおいては、定期検査などの停止中に伝熱管の外表面または内表面にショットブラストなどの冷間加工処理を施し、再運転後硬化層の硬さを測定して伝熱管の温度を推定する。   As in the invention described in claim 5 above, in the existing operation boiler, the outer surface or the inner surface of the heat transfer tube is subjected to a cold working process such as shot blasting during the stoppage of the periodic inspection and the like, and is cured after the reoperation. Estimate the temperature of the heat transfer tube by measuring the hardness of the layer.

請求項１〜５記載の本発明によれば、オーステナイト系耐熱鋼の表面温度推定には従来適用困難であった、汎用性のある簡便な伝熱管表面の硬さ変化を利用する温度推定が可能となる。また、本発明の手法は材料の表面の硬さと運転時間のみで評価できるので、ボイラの定期点検時に評価部位の表面硬さの測定結果と運転時間から運転時の実メタル温度を推定することができ、材料の寿命評価に適用できる。さらに、異常な表面温度など不適合がある部位を早期に発見することが可能となり、伝熱管の噴破などのトラブルを未然に防ぐことができ、ボイラの予防保全に貢献できる。また、高価な装置も必要なく、経済的で汎用性がある。   According to the first to fifth aspects of the present invention, it is difficult to apply to the estimation of the surface temperature of the austenitic heat-resistant steel, and it is possible to estimate the temperature using the simple and versatile hardness of the heat transfer tube surface. It becomes. In addition, since the method of the present invention can be evaluated only by the hardness of the surface of the material and the operation time, it is possible to estimate the actual metal temperature during operation from the measurement result of the surface hardness of the evaluation part and the operation time during the periodic inspection of the boiler. It can be applied to material life evaluation. In addition, it is possible to quickly find a site with incompatibility such as an abnormal surface temperature, so that troubles such as blasting of the heat transfer tube can be prevented in advance, thereby contributing to preventive maintenance of the boiler. Moreover, an expensive apparatus is not required, and it is economical and versatile.

請求項２、３記載の本発明によれば、硬化層に保護カバーを設けているので、腐食環境が厳しい部位であっても、高温酸化量は抑制され、温度推定精度を低下させることなく管外面から温度推定できる。   According to the second and third aspects of the present invention, since the protective cover is provided on the hardened layer, the amount of high-temperature oxidation is suppressed even in a part where the corrosive environment is severe, and the tube is not reduced without lowering the temperature estimation accuracy. Temperature can be estimated from the outside.

以下、本発明の原理を図面により説明する。図１に示すようにオーステナイト系耐熱鋼管１の表面にショットブラスト加工等の冷間加工処理を施すと硬化層２が形成される。硬化層２とは材料表面近傍の結晶粒内に冷間加工に伴うすべり変形を多数発生させて生じる硬化部位のことである。なお図１（ａ）はオーステナイト系耐熱鋼管１の表面側の断面図であり、図１（ｂ）は、顕微鏡によるオーステナイト系耐熱鋼管１の表面側の断面写真である。この硬化層２は、ショット用下降ノズル３から小さな鋼片や鋼球を圧縮空気で噴出させて耐熱鋼管１などの材料表面に衝突させる図２に示すようなショットブラスト加工処理により、容易に形成できる。   The principle of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the hardened layer 2 is formed when the surface of the austenitic heat-resistant steel pipe 1 is subjected to cold working such as shot blasting. The hardened layer 2 is a hardened portion that is generated by generating a large number of slip deformations accompanying cold working in crystal grains in the vicinity of the material surface. 1A is a cross-sectional view of the surface side of the austenitic heat-resistant steel pipe 1, and FIG. 1B is a cross-sectional photograph of the surface side of the austenitic heat-resistant steel pipe 1 using a microscope. The hardened layer 2 is easily formed by shot blasting treatment as shown in FIG. 2 in which small steel pieces or steel balls are ejected from the shot lowering nozzle 3 with compressed air and collide with the material surface such as the heat-resistant steel pipe 1. it can.

冷間加工処理したオーステナイト系耐熱鋼管１の表面近傍の硬さを測定した例を図３に示すが、材料表面近傍の硬さは肉厚中央側より２００Ｈｖ以上硬化し、管表面からの深さ８０μｍまでの範囲では硬さはほぼ一定であるのが分かる。従って、評価には硬さがほぼ一定の範囲である管表面からの深さ８０μｍまでの値を用いることが望ましい。   An example of measuring the hardness near the surface of the cold-worked austenitic heat-resistant steel pipe 1 is shown in FIG. 3. The hardness near the surface of the material is hardened by 200 Hv or more from the thickness center side, and the depth from the pipe surface is shown. It can be seen that the hardness is almost constant in the range up to 80 μm. Therefore, it is desirable to use a value up to a depth of 80 μm from the tube surface where the hardness is in a substantially constant range for evaluation.

次に使用時間及び使用温度が明確な冷間加工処理が施された１８Ｃｒ８Ｎｉオーステナイト系耐熱鋼管１の試験片表面近傍の硬さを測定し、式（１）に示す温度と時間の関数で表されるＬＭＰ（ラーソンミラーパラメータ）と測定硬さをプロットした結果を図４に示す。
ＬＭＰ＝Ｔ×（ｌｏｇｔ＋Ｃ） （１）
ここで、Ｔは温度（Ｋ）、ｔは時間（ｈ）、Ｃは定数である。
なお、上記の定数Ｃは一般的に２０とされるが、必ずしも２０である必要はない。 Next, the hardness in the vicinity of the test piece surface of the 18Cr8Ni austenitic heat-resistant steel pipe 1 subjected to the cold working treatment with a clear use time and use temperature is measured, and is expressed as a function of temperature and time shown in Equation (1). FIG. 4 shows the results of plotting LMP (Larsson mirror parameters) and measured hardness.
LMP = T × (logt + C) (1)
Here, T is temperature (K), t is time (h), and C is a constant.
The constant C is generally 20 but need not necessarily be 20.

図４で示した関係を３次関数で近似すると、下式で表される。
ＬＭＰ＝８．２８×１０3−５．９６×１０2・Ｈｖ＋１．９６・Ｈｖ2−２．１８×１０-3・Ｈｖ3 （２）
ここで、Ｈｖは管表面から深さ４０〜６０μｍの位置の硬さ（Ｈｖ）である。 When the relationship shown in FIG. 4 is approximated by a cubic function, it is expressed by the following equation.
LMP = 8.28 × 10 3 −5.96 × 10 2 · Hv + 1.96 · Hv 2 −2.18 × 10 −3 · Hv 3 (2)
Here, Hv is the hardness (Hv) at a position 40 to 60 μm deep from the tube surface.

本結果では、ＬＭＰと硬さの関係は３次式で表すと最も良い相関を示したので採用したが、対象となるオーステナイト系耐熱鋼により関係式が変化する可能性があるので、３次直線に限定するものではなく、直線や２次直線等の他の関数を使用してもよい。（２）式で示される硬化層２の硬さとＬＭＰの関係式を、各オーステナイト系耐熱鋼管１で作成しておくことで、実機での使用時間と使用後の鋼管１の硬化層２の硬さから、温度を推定することができる。   In this result, the relationship between the LMP and the hardness was adopted because it showed the best correlation when expressed by a cubic equation. However, the relational equation may change depending on the target austenitic heat-resistant steel. However, other functions such as a straight line and a quadratic line may be used. (2) The relationship between the hardness of the hardened layer 2 represented by the formula and the LMP is prepared for each austenitic heat-resistant steel pipe 1 so that the working time in the actual machine and the hardness of the hardened layer 2 of the steel pipe 1 after use are as follows. From this, the temperature can be estimated.

推定方法としては、温度推定したいオーステナイト系耐熱鋼管１の表面にショットブラスト加工処理により硬化層２を形成させる。次にこの硬化層２を形成させた鋼管１を実機の高温部である期間使用し、使用後に鋼管１の硬化層２の硬さを測定する。実機での使用時間を５０，０００ｈ、使用後の硬化層２の硬さを２５０Ｈｖとした場合、（１）及び（２）式を用いて温度を推定すると、図５に示すように管表面の温度は６２６℃と推定できる。９５％信頼区間上限値は６５５℃となり平均値より２９℃高い値を示すが、この信頼範囲については、硬さとＬＭＰの関係式（２）式をデータ数を増加させて改良することにより、小さくすることも可能である。   As an estimation method, the hardened layer 2 is formed on the surface of the austenitic heat-resistant steel pipe 1 whose temperature is to be estimated by shot blasting. Next, the steel pipe 1 on which the hardened layer 2 is formed is used for a period that is a high temperature part of an actual machine, and the hardness of the hardened layer 2 of the steel pipe 1 is measured after use. When the use time in the actual machine is 50,000 h and the hardness of the hardened layer 2 after use is 250 Hv, the temperature is estimated using the equations (1) and (2), as shown in FIG. The temperature can be estimated at 626 ° C. The upper limit of the 95% confidence interval is 655 ° C., which is 29 ° C. higher than the average value, but this confidence range is reduced by improving the equation (2) of hardness and LMP by increasing the number of data. It is also possible to do.

このようにして、本発明により、使用時間と硬さから実機の伝熱管表面の温度を推定することができる。なお、温度と時間の関数にＬＭＰ（ラーソンミラーパラメータ）を使用して説明したが、特にこれに限定するものではなく、例えばＯＳＤ（Ｏｒｒ−Ｓｈｅｒｂｙ−Ｄｏｒｎ）パラメータやＭＨ（Ｍｎｓｏｎ−Ｈａｆｅｒｄ）パラメータを使用してもよい。   In this way, according to the present invention, the temperature of the actual heat transfer tube surface can be estimated from the use time and hardness. In addition, although it demonstrated using LMP (Larson mirror parameter) for the function of temperature and time, it does not specifically limit to this, For example, OSD (Orr-Shelby-Dorn) parameter and MH (Mnson-Haferd) parameter are used. May be used.

上記の実施例１では、材料表面近傍の硬さを用いた温度推定原理と方法について説明した。実際に実機のオーステナイト系耐熱鋼管１の外面から温度を推定する場合、図６に示すように、温度を測定したい鋼管１の管外面に冷間加工による硬化層２を形成させ、温度推定に適用する。管外面の場合、燃焼ガスや付着灰による高温酸化が生じるため、ブラシや脱スケール溶液などにより管表面の酸化物を除去した後、ポータブル硬度計を用いて硬さを測定する。   In the first embodiment, the temperature estimation principle and method using the hardness in the vicinity of the material surface have been described. When the temperature is actually estimated from the outer surface of the actual austenitic heat-resistant steel pipe 1, as shown in FIG. 6, a hardened layer 2 is formed by cold working on the outer surface of the steel pipe 1 whose temperature is to be measured, and applied to the temperature estimation. To do. In the case of the outer surface of the tube, high temperature oxidation due to combustion gas or adhering ash occurs. Therefore, after removing the oxide on the surface of the tube with a brush or descaling solution, the hardness is measured using a portable hardness meter.

ただし、より高温で使用期間が長い場合には高温酸化量が増加するため、硬さ測定の推奨範囲である表面からの深さ８０μｍ以上減肉し、推定精度が著しく低下する可能性がある。従って、腐食環境が厳しい部位には図７に示すように、硬化層２を高耐食性のステンレス製の保護カバー４で覆うことが望ましい。保護カバー４により高温酸化量は抑制され、温度推定精度を低下させることなく管外面から温度推定できる。鋼管表面の酸化防止についてはステンレス製の酸化防止保護カバー４に限定するものでなく、例えば耐熱塗料などの皮膜を使用してもよい。
なお、管外面への硬化層形成は定期点検期間中に新たに形成することが可能であり、既存のボイラのオーステナイト系耐熱鋼管１にも適用できる。 However, since the amount of high-temperature oxidation increases when the use period is longer at a higher temperature, there is a possibility that the estimation accuracy will be significantly reduced by reducing the thickness by 80 μm or more from the surface, which is the recommended range of hardness measurement. Therefore, as shown in FIG. 7, it is desirable to cover the hardened layer 2 with a protective cover 4 made of stainless steel having high corrosion resistance at a site where the corrosive environment is severe. The amount of high-temperature oxidation is suppressed by the protective cover 4, and the temperature can be estimated from the outer surface of the pipe without reducing the temperature estimation accuracy. The oxidation prevention on the surface of the steel pipe is not limited to the oxidation protection protective cover 4 made of stainless steel. For example, a film such as a heat resistant paint may be used.
In addition, the hardened layer formation on the pipe outer surface can be newly formed during the periodic inspection period, and can also be applied to the austenitic heat resistant steel pipe 1 of an existing boiler.

上記の実施例１，２では鋼管外表面から温度推定する適用例を示したが、オーステナイト系耐熱鋼管１の管内表面に硬化層２を形成させて、温度推定に使用してもよい。管内表面の硬さ測定は鋼管１を切断・抜管し、断面で硬さを測定する必要があるが、切断・復旧工事は定期点検期間中に比較的容易に行うことができるため、可能である。また、管内表面への硬化層２の形成は、図８に示すように管内面の水蒸気酸化抑制用にショット加工を施す装置があり、容易に施工可能である。   In the first and second embodiments, the application example in which the temperature is estimated from the outer surface of the steel pipe is shown. However, the hardened layer 2 may be formed on the inner surface of the austenitic heat-resistant steel pipe 1 and used for temperature estimation. It is necessary to measure the hardness of the inner surface of the pipe by cutting / extracting the steel pipe 1 and measuring the hardness at the cross section, but it is possible because cutting and restoration work can be performed relatively easily during the regular inspection period. . Further, the formation of the hardened layer 2 on the inner surface of the pipe can be easily performed by a device that performs shot processing for suppressing water vapor oxidation on the inner surface of the pipe as shown in FIG.

上記の実施例１〜３ではボイラ管への適用例を示したが、高温で使用される機器であれば、化学装置に使用されるオーステナイト系耐熱鋼等にも広く適用できる。   In Examples 1 to 3 described above, an example of application to a boiler tube has been shown. However, as long as the equipment is used at a high temperature, it can be widely applied to austenitic heat-resisting steels used in chemical equipment.

上記の実施例１〜３では新設ボイラ管への適用例を示したが、高温で使用される機器であれば、既設運転中のプラントに使用されているオーステナイト系耐熱鋼等にも広く適用できる。この場合は、定期点検などの停止中に管の外表面又は内表面にショットブラストなどの冷間加工処理を施し、再運転後にその部分の硬さ測定結果とその間の運転時間から伝熱管温度が推定できる。   In Examples 1 to 3 described above, an example of application to a new boiler pipe has been shown. However, as long as the equipment is used at a high temperature, it can be widely applied to austenitic heat-resistant steel and the like used in existing plants. . In this case, cold work such as shot blasting is performed on the outer or inner surface of the pipe during periodic inspections, etc., and after re-operation, the heat transfer tube temperature is determined from the hardness measurement result of that part and the operating time during that time. Can be estimated.

発電プラントの発電効率向上のため、ボイラ蒸気条件はさらなる高温・高圧化が予想され、高温部過熱器管や再熱器管の実温度推定は材料寿命評価に不可欠であり、本発明はより一層重要となる。   In order to improve the power generation efficiency of power plants, boiler steam conditions are expected to be further increased in temperature and pressure, and estimation of actual temperatures of high-temperature superheater tubes and reheater tubes is indispensable for material life evaluation. It becomes important.

本発明になる実施例に用いたオーステナイト系耐熱鋼管の硬化層形成分部の断面図（図１（ａ））と断面写真（図１（ｂ））である。It is sectional drawing (FIG. 1 (a)) and sectional photograph (FIG.1 (b)) of the hardened layer formation part of the austenitic heat-resistant steel pipe used for the Example which becomes this invention. 本発明になる実施例に用いたオーステナイト系耐熱鋼管へのショット加工方法の説明図である。It is explanatory drawing of the shot processing method to the austenitic heat-resistant steel pipe used for the Example which becomes this invention. 本発明になる実施例に用いたオーステナイト系耐熱鋼管の表面からの距離と表面の硬さの関係を示す図である。It is a figure which shows the relationship between the distance from the surface of the austenitic heat-resistant steel pipe used for the Example which becomes this invention, and the hardness of the surface. 本発明の効果を説明するためのＬＭＰとオーステナイト系耐熱鋼管の表面の硬さの関係を示す図である。It is a figure which shows the relationship between the hardness of LMP and the surface of an austenitic heat-resistant steel pipe for demonstrating the effect of this invention. 本発明の効果を説明するための使用時間及び使用後の管表面硬さからの温度推定するショット層の硬さと温度の関係を示す図である。It is a figure which shows the relationship between the use time for explaining the effect of this invention, and the hardness of the shot layer which estimates the temperature from the tube surface hardness after use, and temperature. 本発明になる実施例に用いたオーステナイト系耐熱鋼管外面へのショット加工方法を説明する図である。It is a figure explaining the shot processing method to the austenitic heat-resistant steel pipe outer surface used for the example used as the present invention. 本発明になる実施例に用いた管外面にショット加工を施した後、保護カバーを設置したオーステナイト系耐熱鋼管の斜視図である。It is a perspective view of the austenitic heat-resistant steel pipe which installed the protective cover after giving shot processing to the pipe outer surface used for the example used as the present invention. 本発明になる実施例に用いたオーステナイト系耐熱鋼管内面へのショット加工方法を説明する図である。It is a figure explaining the shot processing method to the austenitic heat-resistant steel pipe inner surface used for the Example which becomes this invention.

符号の説明Explanation of symbols

１ オーステナイト系耐熱鋼管
２ ショット加工による硬化層
３ ショット加工用ノズル
４ 酸化防止保護カバー 1 Austenitic heat-resistant steel pipe 2 Hardened layer by shot processing 3 Nozzle for shot processing 4 Antioxidation protective cover

Claims (5)

発電用ボイラステンレス鋼管に用いられるオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法において、
試験片の表面に冷間加工処理により硬化層を形成させ、
該硬化層の硬さと、使用時間と使用温度との関数で表されるＬＭＰ（ラーソンミラーパラメータ）との関係を予め求めておき、
次に実際に使用する前のオーステナイト系ステンレス鋼管の外表面に冷間加工処理により硬化層を形成させた後に、実際に高温で使用した当該硬化層の硬さを測定し、前記予め求めていた硬化層の硬さと、使用時間とＬＭＰとの関係式から当該オーステナイト系ステンレス鋼管の実際の使用温度を推定することを特徴とするオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法。 In the method of estimating the actual operating temperature of the austenitic stainless steel pipe used for the boiler stainless steel pipe for power generation,
A hardened layer is formed on the surface of the test piece by cold working,
The relationship between the hardness of the hardened layer and the LMP (Larsson mirror parameter) expressed as a function of the use time and the use temperature is obtained in advance.
Next, after forming a hardened layer by cold working on the outer surface of the austenitic stainless steel pipe before actual use, the hardness of the hardened layer actually used at a high temperature was measured and determined in advance. A method for estimating an actual use temperature of an austenitic stainless steel pipe, characterized by estimating an actual use temperature of the austenitic stainless steel pipe from a relational expression of hardness of a hardened layer, use time, and LMP. 前記実際に使用する前のオーステナイト系ステンレス鋼管の外表面に形成した硬化層の表面に保護カバーを設けたことを特徴とする請求項１記載のオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法。   2. A method for estimating an actual use temperature of an austenitic stainless steel pipe according to claim 1, wherein a protective cover is provided on the surface of the hardened layer formed on the outer surface of the austenitic stainless steel pipe before the actual use. . 前記実際に使用する前のオーステナイト系ステンレス鋼管の外表面に形成した硬化層の表面に保護皮膜からなる被覆部を設けたことを特徴とする請求項１記載のオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法。   The actual operating temperature of the austenitic stainless steel pipe according to claim 1, wherein a coating portion made of a protective film is provided on the surface of the hardened layer formed on the outer surface of the austenitic stainless steel pipe before the actual use. How to estimate. 発電用ボイラステンレス鋼管に用いられるオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法において、
試験片の表面に冷間加工処理により硬化層を形成させ、
該硬化層の硬さと、使用時間と使用温度との関数で表されるＬＭＰ（ラーソンミラーパラメータ）との関係を予め求めておき、
次に実際に使用する前のオーステナイト系ステンレス鋼管の内表面に冷間加工処理により硬化層を形成させた後に、実際に高温で使用した当該硬化層の硬さを測定し、前記予め求めていた硬化層の硬さと、使用時間とＬＭＰとの関係式から当該オーステナイト系ステンレス鋼管の実際の使用温度を推定することを特徴とするオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法。 In the method of estimating the actual operating temperature of the austenitic stainless steel pipe used for the boiler stainless steel pipe for power generation,
A hardened layer is formed on the surface of the test piece by cold working,
The relationship between the hardness of the hardened layer and the LMP (Larsson mirror parameter) expressed as a function of the use time and the use temperature is obtained in advance.
Next, after forming a hardened layer by cold working on the inner surface of the austenitic stainless steel pipe before actual use, the hardness of the hardened layer actually used at a high temperature was measured and determined in advance. A method for estimating an actual use temperature of an austenitic stainless steel pipe, characterized by estimating an actual use temperature of the austenitic stainless steel pipe from a relational expression of hardness of a hardened layer, use time, and LMP. 発電用ボイラステンレス鋼管に用いられるオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法において、試験片の表面に冷間加工処理により硬化層を形成させて該硬化層の硬さと、使用時間と使用温度との関数で表されるＬＭＰ（ラーソンミラーパラメータ）との関係を予め求めておき、次に既運転中のオーステナイト系ステンレス鋼管の外表面または内表面に冷間加工処理により硬化層を形成させた後に、さらに再運転後に実際に高温で使用した当該硬化層の硬さを測定し、前記予め求めていた硬化層の硬さと、使用時間とＬＭＰとの関係式から当該オーステナイト系ステンレス鋼管の実際の使用温度を推定することを特徴とするオーステナイト系ステンレス鋼管の実際の使用温度を推定する方法。   In a method for estimating the actual operating temperature of an austenitic stainless steel pipe used for boiler stainless steel pipes for power generation, a hardened layer is formed on the surface of the test piece by cold working, and the hardness of the hardened layer, the usage time, and the usage A relationship with LMP (Larson Miller parameter) expressed as a function of temperature is obtained in advance, and then a hardened layer is formed by cold working on the outer surface or inner surface of an already operated austenitic stainless steel pipe. After that, the hardness of the hardened layer actually used at a high temperature after re-operation is measured, and the actual condition of the austenitic stainless steel pipe is calculated from the relationship between the hardness of the hardened layer determined in advance and the use time and LMP. A method for estimating the actual use temperature of an austenitic stainless steel pipe, characterized by estimating the use temperature of the austenitic stainless steel pipe.
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JP2006208214A (en) * 2005-01-28 2006-08-10 Babcock Hitachi Kk Thermal history estimating method of heat-resistant member
WO2007057946A1 (en) * 2005-11-15 2007-05-24 Nittan Valve Co., Ltd. Coolant-containing hollow poppet valve and process for producing the same

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012137385A (en) * 2010-12-27 2012-07-19 Mitsubishi Heavy Ind Ltd Temperature estimation method of high temperature member and lifetime determination method of high temperature member
CN103267683A (en) * 2013-04-28 2013-08-28 扬州大学 Method for determining remaining life of heat-resisting metal material
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