JP6976894B2 - Material life evaluation method, evaluation device, and evaluation program - Google Patents

Description

The present invention relates to a material life evaluation method, an evaluation device, and an evaluation program. More specifically, the present invention relates to a technique suitable for use in evaluating the creep life of a welded portion of an improved 9Cr-1Mo steel pipe, for example, as a main steam pipe of a thermal power plant or a high temperature reheat steam pipe.

For 600 ° C class thermal power plants, evaluation of creep life in improved 9Cr-1Mo steel welds in main steam pipes and high temperature reheat steam pipes is an important issue to be examined. There is a large difference (called "heat difference") in the creep life of high temperature structural materials, including the improved 9Cr-1Mo steel, even under the same test conditions (in other words, under the same load conditions). (Non-Patent Document 1 is mentioned as an example of study on the difference between heats of Cr steel).

Fujio Abe, "Difference between heats in creep life of 12% Cr steel and long-term strength deterioration behavior", Materials and Processes (CD-ROM), Vol. 21 No. 2, The Iron and Steel Institute of Japan, 2008

At the design stage, the heat of the material actually used in each structure is unknown, so the difference between the heats of the material is taken into account as part of the safety factor in setting the allowable tensile stress. On the other hand, at the stage of evaluating the remaining life, the heat of the material actually used for the structure to be evaluated is known, so it is considered possible to consider the difference between the heats of the material in principle. Be done. However, little study has been made on the remaining life evaluation technique focusing on this point. In order to estimate the remaining life of high-temperature structures with high accuracy, it is necessary to establish a creep life evaluation method that can take into account the material properties unique to each structure.

Therefore, the present invention relates to a material life evaluation method, an evaluation device, and an evaluation program capable of evaluating creep life in consideration of material properties / creep characteristics (in other words, heat difference) peculiar to each material. The purpose is to provide.

As a result of systematic tests and evaluations by the inventor, it was found that the creep rupture characteristics of welded joints in pipes depend on the creep rupture characteristics of the base metal.

Specifically, as a result of estimating the "initial creep life" of the base metal and the welded joint based on the results of creep tests on multiple long-term use materials related to the improved 9Cr-1Mo steel piping and the history of actual machine operation, As shown in the example shown in FIG. 7, there is a correlation between the creep characteristics of the base metal and the creep characteristics of the welded joint, and it was found that the higher the strength of the base metal, the higher the strength of the welded joint. Was done. Here, the "initial creep life" of the material is defined as the creep rupture time (that is, the above-mentioned actual machine operating conditions) under the conditions (specifically, temperature, circumferential stress) that each material used for a long time is applied during the actual machine operation. The corresponding "remaining creep life") is calculated, and the calculated "remaining creep life" is the value added to the operating time of the actual machine (Masatsugu Yaguchi et al. "Improved 9Cr- in the region over 100,000 hours". 1Mo Steel Welded Joint Creep Strength Estimate ”, High Temperature Strength / Fracture Mechanics Joint Symposium 55th High Temperature Strength Symposium 18th Fracture Mechanics Symposium Proceedings, 118, 119-123, 2017).

In FIG. 7, the horizontal axis indicates the “initial creep life” estimated for each base material at 650 ° C. and 60 MPa, and the “2015 data study group base material (plate material) average characteristics” (K. Kimura et al. "Re-evolution of Long-term Creep Strength of Base Metal of ASME Grade 91 Type Steel", Proc. PVP20166, Vancouver, Vancover, Canada, PVP2016 "Initial creep life" estimated for the actual operating conditions (specifically, temperature, circumferential stress) of each welded joint is "2015 Data Study Group Welded Joint Average Characteristics" (M. Yaguchi et al. "Re" -Evolution of Long-term Creep Strength of Welded Joint of ASME Grade 91 Type Steel ", Proc. PVP20166, Vancouver, Canda, PVP2016-63316, 2016).

From this, a positive correlation is found between the initial creep characteristics of the welded joint and the initial creep characteristics of the base metal, that is, the initial creep characteristics of the welded joint depend on the base metal, and the initial creep characteristics of the base metal It was found that the higher the creep characteristic, the higher the initial creep characteristic of the welded joint. That is, the creep characteristic / heat difference of the welded portion of each pipe depends on the creep characteristic / heat difference of the base material portion of the pipe, and therefore the creep characteristic / heat difference of the base material portion of each pipe is evaluated. It was found that the creep characteristics / heat difference between the welded parts of the pipe can be estimated.

The method for evaluating the material life of the present invention is based on the above-mentioned original knowledge of the inventor, and corresponds to the number density of vanadium-based precipitates and the result of the standard creep test for the sample collected from the base material of chrome steel. Based on this, the precipitate reflection coefficient corresponding to the number density of vanadium-based precipitates in the sample is calculated, and the correspondence between the results of the small punch creep test and the results of the standard creep test for the test piece collected from the base metal portion of the chrome steel is obtained. The long-term behavior reflection coefficient corresponding to the result of the small punch creep test of the test piece is calculated based on the above, and the base metal part characteristic coefficient is specified based on the value of the precipitate reflection coefficient and the value of the long-term behavior reflection coefficient. Based on the correspondence between the result of the standard creep test of the base metal part and the result of the standard creep test of the welded part, the value of the welded part characteristic coefficient corresponding to the value of the base metal part characteristic coefficient is specified, and the welded part characteristic coefficient is specified. The value of is used to calculate the break time of the welded part of chrome steel.

In addition, the material life evaluation device is a precipitation corresponding to the number density of vanadium-based precipitates of the sample based on the correspondence between the number density of vanadium-based precipitates and the result of the standard creep test for the sample collected from the base metal portion of the chrome steel. The result of the small punch creep test of the test piece based on the correspondence between the result of the small punch creep test and the result of the standard creep test for the test piece collected from the base material part of the chrome steel and the means for calculating the object reflection coefficient. A means for calculating the long-term behavior reflection coefficient corresponding to the above, a means for specifying the base metal part characteristic coefficient based on the value of the precipitate reflection coefficient and the value of the long-term behavior reflection coefficient, and the result of the standard creep test of the base material part. And the value of the welded part characteristic coefficient corresponding to the value of the base metal part characteristic coefficient is specified based on the correspondence with the result of the standard creep test of the welded part, and the value of the welded part characteristic coefficient is used to specify the value of the welded part of chrome steel. It has a means to calculate the breaking time of the steel.

In addition, the material life evaluation program is based on the correspondence between the number density of vanadium-based precipitates and the result of the standard creep test for the sample collected from the base metal part of the chrome steel, and the precipitation corresponding to the number density of vanadium-based precipitates of the sample. The result of the small punch creep test of the test piece based on the process of calculating the object reflection coefficient and the correspondence between the result of the small punch creep test and the result of the standard creep test for the test piece collected from the base material of the chrome steel. The process of calculating the long-term behavior reflection coefficient corresponding to the above, the process of specifying the base metal part characteristic coefficient based on the value of the precipitate reflection coefficient and the value of the long-term behavior reflection coefficient, and the result of the standard creep test of the base material part. And the value of the welded part characteristic coefficient corresponding to the value of the base metal part characteristic coefficient is specified based on the correspondence with the result of the standard creep test of the welded part, and the value of the welded part characteristic coefficient is used to specify the value of the welded part of chrome steel. The process of calculating the break time of the steel is performed by the computer.

Therefore, according to these material life evaluation methods, material life evaluation devices, and material life evaluation programs, the creep characteristics of the base material are evaluated using samples collected from the base material of chrome steel. Based on the evaluation result, the creep life (in other words, creep rupture characteristics) of the welded portion of the chrome steel is evaluated. Therefore, the creep rupture characteristics (in other words, the difference between heats) peculiar to each material / member are taken into consideration in the life evaluation of the welded part of the material / member, so that the welded part of each material / member has the peculiarity. The life is evaluated to reflect the creep rupture characteristics of.

Further, in the material life evaluation method, the material life evaluation device, and the material life evaluation program of the present invention, the chromium steel may be an improved 9Cr-1Mo steel. In this case, the above-mentioned action is exhibited in the life evaluation of the welded portion of the improved 9Cr-1Mo steel.

According to the material life evaluation method, the material life evaluation device, and the material life evaluation program of the present invention, the creep rupture characteristics (in other words, the difference between heats) peculiar to each material / member are determined for the material / member. Since it is taken into consideration in the life evaluation of the welded part, it is possible to perform the life evaluation that reflects the creep rupture characteristics of the welded part of each material / member, and the life of each material / member is in line with the substance. It is possible to improve the estimation accuracy of the life evaluation by performing the evaluation, and it is possible to improve the reliability of the life evaluation. In particular, in the conventional evaluation of remaining life, 99% reliability lower limit characteristics are uniformly used for all pipes, which tends to give conservative results, whereas in the present invention, each material / member is actually used. Since the material properties corresponding to the strength of the above are used, it becomes possible to give more rational evaluation results.

When the material life evaluation method, the material life evaluation device, and the material life evaluation program of the present invention are applied to the improved 9Cr-1Mo steel, the life of the welded portion of the improved 9Cr-1Mo steel is applied. In the evaluation, it becomes possible to exert the above-mentioned action and effect.

It is a flowchart explaining an example of embodiment of the material life evaluation method which concerns on this invention. It is a functional block diagram of the material life evaluation apparatus realized by the program when the material life evaluation method of an embodiment is carried out using a material life evaluation program. It is a figure which shows an example of the relationship between the number density of the precipitate, and the normalized life of the base metal part of a pipe. It is a figure which shows an example of the apparatus used in a small punch creep test. It is a figure which shows an example of the relationship between breaking time and stress. It is a cross-sectional view orthogonal to the pipe axis direction of the base material part of the pipe explaining the position of sampling. It is a figure which shows an example of the relationship between the creep property of a base material of a pipe, and the creep property of a welded joint.

Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings. In the following explanation, in order to clarify that a predetermined symbol or phrase is a unit, the symbol or phrase used as a unit may be enclosed in [].

In FIGS. 1 to 6, the material life evaluation method, the material life evaluation device, and the material life evaluation program according to the present invention are described as improved 9Cr-1Mo steel in an actual machine (note that it is also referred to as “fire SCMV28” as a kind symbol. An example of an embodiment when applied to the evaluation of the creep life of a welded portion / welded joint of a pipe is shown.

The method for evaluating the material life of the present embodiment corresponds to the number density of vanadium-based precipitates in the sample collected from the base metal portion of the chrome steel based on the correspondence between the number density of vanadium-based precipitates and the result of the standard creep test. (S1, S2, S3) and the test pieces collected from the base material of chrome steel are tested based on the correspondence between the results of the small punch creep test and the results of the standard creep test. The long-term behavior reflection coefficient corresponding to the result of the small punch creep test of one piece is calculated (S1, S4, S5), and the base metal part characteristic coefficient is specified based on the value of the precipitate reflection coefficient and the value of the long-term behavior reflection coefficient. (S6), the value of the welded portion characteristic coefficient corresponding to the value of the base metal portion characteristic coefficient is specified based on the correspondence between the result of the standard creep test of the base metal portion and the result of the standard creep test of the welded portion. The value of the welded portion characteristic coefficient is used to calculate the breaking time of the welded portion of chrome steel (S7) (see FIG. 1).

The material life evaluation method may be carried out by the material life evaluation device according to the present invention. The material life evaluation device of the present embodiment corresponds to the number density of vanadium-based precipitates of the sample collected from the base metal portion of the chrome steel based on the correspondence between the number density of vanadium-based precipitates and the result of the standard creep test. Small punch creep test of the test piece based on the correspondence between the result of the small punch creep test and the result of the standard creep test for the test piece collected from the base metal part of the chrome steel and the means for calculating the precipitate reflection coefficient. A means for calculating the long-term behavior reflection coefficient corresponding to the result of The value of the welded part characteristic coefficient corresponding to the value of the base metal part characteristic coefficient is specified based on the correspondence between the result of It has a means for calculating the breaking time of the welded portion.

The material life evaluation method and the material life evaluation device can also be implemented and realized by executing the material life evaluation program on a computer. Here, a case where the material life evaluation method is implemented and the material life evaluation device is realized by executing the material life evaluation program on a computer will be described.

FIG. 2 shows the overall configuration of the computer 10 (also the material life evaluation device 10 in the present embodiment) for executing the material life evaluation program 17 of the present embodiment.

The computer 10 (material life evaluation device 10) includes a control unit 11, a storage unit 12, an input unit 13, a display unit 14, and a memory 15, which are connected to each other by a signal line such as a bus.

The control unit 11 controls the entire computer 10 and performs calculations related to the evaluation of the material life according to the material life evaluation program 17 stored in the storage unit 12, and is, for example, a CPU (Central Processing Unit).

The storage unit 12 is a device capable of storing at least data and programs, and is, for example, a hard disk.

The input unit 13 is an interface (that is, an information input mechanism) for giving at least a worker's command and various information to the control unit 11, and is, for example, a keyboard or a mouse. It should be noted that a plurality of types of interfaces such as both a keyboard and a mouse may be provided as the input unit 13.

The display unit 14 draws and displays characters, figures, images, and the like under the control of the control unit 11, and is, for example, a display.

The memory 15 is a memory space that is a work area when the control unit 11 executes various controls and operations, and is, for example, a RAM (abbreviation of Random Access Memory).

Further, a signal line such as a bus or a wide area network line is used so that the computer 10 can send and receive signals such as data and control commands (that is, input / output) to and from the computer 10 as needed. The data server 20 may be connected. Further, the computer 10 may be able to access a cloud server (not shown) via a network such as the Internet, if necessary.

Then, the control unit 11 of the computer 10 (hereinafter referred to as "material life evaluation device 10") is executed with the material life evaluation program 17, and the sample collected from the base material portion of the chrome steel is executed. The precipitate reflection unit 11a that performs the process of calculating the precipitate reflection coefficient corresponding to the number density of the vanadium-based precipitate of the sample based on the correspondence between the number density of the vanadium-based precipitate and the result of the standard creep test, and the mother of the chrome steel. A process is performed to calculate the long-term behavior reflection coefficient corresponding to the result of the small punch creep test of the test piece based on the correspondence between the result of the small punch creep test and the result of the standard creep test for the test piece collected from the material part. Results of standard creep test of long-term behavior reflection unit 11b, characteristic evaluation unit 11c that performs processing to specify the characteristic coefficient of the base metal part based on the value of the precipitation reflection coefficient and the value of the long-term behavior reflection coefficient, and the standard creep test of the base material part. And the value of the welded part characteristic coefficient corresponding to the value of the base metal part characteristic coefficient is specified based on the correspondence with the result of the standard creep test of the welded part, and the value of the welded part characteristic coefficient is used to specify the value of the welded part of chrome steel. It is configured with a life calculation unit 11d that performs a process of calculating the breaking time of the steel.

The procedure according to the present invention largely includes processing related to the base metal portion (S1 to S6) and processing related to the welded portion (S7) after the database is prepared.

When implementing the material life evaluation method, a database of microstructures, a database of creep tests, and a database of creep rupture characteristics are prepared and prepared (referred to as "S0" for convenience).

<< Database of microscopic tissue >>
The microstructure database stores data on the relationship between the microstructure and long-term creep properties (in other words, creep rupture properties) for the improved 9Cr-1Mo steel.

Specifically, various improved 9Cr-1Mo in a state of being used for a long time (specifically, for example, about 50,000 to 150,000 hours; the same applies to the "long time" in the following) in a 600 ° C. class thermal power plant, for example. The base metal of the steel pipe is used as the sample for analysis, and the microscopic structure is observed and analyzed, and the creep test is performed. A database is constructed by accumulating combination data of the number density of precipitates obtained as a result of observation and analysis and the creep characteristics obtained as a result of a creep test.

Specifically, for observation and analysis of the microscopic tissue, for example, a transmission electron microscope (also referred to as “TEM”) is used to measure the number density of the precipitate.

Here, the target material has a hierarchical structure such as an old austenite grain boundary, a packet boundary / block boundary, and a lath, and the state of the microstructure differs significantly depending on the location. Therefore, in order to reduce the influence of the observation location on the analysis results, a predetermined observation area is targeted according to each precipitate, and high resolution (specifically, high resolution (specifically,) so that there is no omission of analysis of fine precipitates). For example, it is preferable to measure the number density of the precipitate at (about 4 nm).

As the creep test, a creep test is performed using a standard test piece in accordance with Japanese Industrial Standards JIS Z2271 "Creep and creep rupture test method for metal materials". In the description of the present invention, the creep test performed by using the standard test piece is also referred to as "standard creep test".

FIG. 3 shows an example of the relationship between the number density of precipitates and the initial creep life of the base material of the improved 9Cr-1Mo steel pipe. The "initial creep life" of the material is the same as that described in relation to FIG. 7 above (Masatsugu Yaguchi et al., "Creep strength of the improved 9Cr-1Mo steel welded joint in the region exceeding 100,000 hours". Estimate "(supra)).

From FIG. 3, the number densities of chromium (Cr) -based precipitates (mainly M ₂₃ C ₆ : however, M = Cr, Fe) and molybdenum (Mo) -based precipitates (mainly Rabes phase) and the base material portion. Vanadium (V) -based precipitates (mainly MX: but M = V, Nb, and X = C, N; especially vanadium knights; while no correlation was found with the initial creep lifetime of It is confirmed that a positive correlation is observed between the number density of the ride (VN)) and the initial creep life of the base metal.

From the results shown in FIG. 3, by measuring the number density of vanadium-based precipitates in the base material of each of the improved 9Cr-1Mo steel pipes, the unique creep rupture characteristics of each material / member (in other words, the difference between heats). It is confirmed that the creep life reflecting the above can be evaluated.

^{In this embodiment, the number density [μm -2} ] of vanadium-based precipitates for each base material of the improved 9Cr-1Mo steel pipe (particularly the material used) as a sample for analysis and the result of the standard creep test (specifically, the test). A data file in which a plurality of combined data such as temperature, test stress, breaking time, etc. are accumulated is stored in the data server 20 as a database 21 of the microstructure.

In addition, information on the operating conditions (specifically, operating temperature [° C], operating stress [MPa], etc.) and usage time [time] of each of the above analysis samples in the actual machine is information on each of the above combination data. It is maintained in association with.

《Creep test database》
The creep test database stores data on the relationship between the results of the creep test in the short time domain and the creep properties (in other words, creep rupture properties) in the long time domain for the improved 9Cr-1Mo steel. Will be done.

Specifically, for example, a plurality of improved 9Cr-1Mo steel pipe base materials that have been used for a long time in a 600 ° C class thermal power plant are used as analysis samples, and a creep test is performed by a small punch and standard. A creep test with a test piece (ie, a standard creep test) is performed, and combined data of creep characteristics obtained as a result of two types of creep tests for two analytical samples taken from the same base material are accumulated. The database is configured.

As the creep test by the small punch (SP), for example, the apparatus shown in FIG. 4 is used, and a test piece having the following specifications (referred to as “SP test piece”) is used in accordance with the following test conditions. A creep test is performed.
<Specifications of SP test piece>
Diameter: 8 mm
Plate thickness: 0.5 mm ± 0.005 mm
Polishing: Wet alumina mirror polishing finish <Creep test conditions>
Temperature: 650 ° C
Load: 190,230,300 N
Atmosphere: High-purity argon (Ar) gas (99.99%), 150 ml / min

As the creep test using the standard test piece, a creep test (that is, a standard creep test) is performed using the standard test piece in accordance with Japanese Industrial Standards JIS Z2271 "Creep and creep rupture test method for metal materials".

The results of a creep test using a small punch (specifically, for example, a test according to the above specifications and conditions) and a creep test using a standard test piece (specifically, a test according to the above specifications and conditions) for two analytical samples collected from the same base material. , JIS Z2271 (test according to JIS Z2271), an example of the relationship with the result is shown in FIG. The white plots in the figure are the results of the creep test using the standard test piece, and the black plots are the results of the creep test using the small punch.

From the results shown in FIG. 5, the order of the heat difference is the same between the result of the creep test by the small punch and the result of the creep test by the standard test piece, and therefore the creep test by the small punch can be performed in a relatively short time. It can be confirmed that the order of the difference between heats in the long-term region of the standard test piece can be reproduced well, and the creep characteristics in the long-term region can be evaluated from the results of the short-term test. Is confirmed.

In this embodiment, the result of a creep test by a small punch for each base material of the improved 9Cr-1Mo steel pipe (particularly, the material used) as a sample for analysis (specifically, test temperature, test stress, rupture time, etc.). A data file in which a plurality of combination data of the creep test result (specifically, test temperature, test stress, rupture time, etc.) and the result of the creep test using the standard test piece are accumulated is stored in the data server 20 as the creep test database 22. ..

In addition, information on the operating conditions (specifically, operating temperature [° C], operating stress [MPa], etc.) and usage time [time] of each of the above analysis samples in the actual machine is information on each of the above combination data. It is maintained in association with.

<< Database of creep rupture characteristics >>
The database of creep rupture properties stores data on the relationship between the results of the standard creep test of the base metal and the results of the standard creep test of the weld for the improved 9Cr-1Mo steel.

Specifically, for example, a creep test is performed using a plurality of base materials and welded joints of improved 9Cr-1Mo steel pipes that have been used for a long time in a 600 ° C class thermal power plant as analysis samples, and the same. A database is constructed by accumulating combination data of creep characteristics obtained as a result of two creep tests relating to two analytical samples collected from each of the base metal part and the welded joint part of the pipe.

As the creep test, a creep test (that is, a standard creep test) is performed using a standard test piece in accordance with Japanese Industrial Standards JIS Z2271 "Creep and creep rupture test method for metal materials".

In this embodiment, the result of the standard creep test of the base metal portion for each improved 9Cr-1Mo steel pipe (particularly, the material used) as a sample for analysis (specifically, test temperature, test stress, rupture time, etc.). A data file containing a plurality of combination data of the standard creep test results (specifically, test temperature, test stress, rupture time, etc.) of the welded joint is stored in the data server 20 as the creep rupture characteristic database 23. Will be done.

In addition, information on the operating conditions (specifically, operating temperature [° C], operating stress [MPa], etc.) and usage time [time] of each of the above analysis samples in the actual machine is information on each of the above combination data. It is maintained in association with.

In the above-mentioned three databases used in the present invention, existing data may be used / collected and maintained, or data may be newly acquired and maintained, and further. Speaking of which, existing data and new data may be combined and maintained. In addition, the above three databases may be treated as fixed once they are maintained, or they may be updated in a timely manner by adding new data as needed after they are maintained. You may do so.

Then, as a procedure related to the processing related to the base material portion when the material life evaluation method is implemented, first, a sample is collected from the base material portion of the actual machine piping (S1).

Specifically, for example, a sample is taken from a position near the outer surface of the base material of the actual machine piping (FIG. 6). In the present invention, the sample collected from the base material of the actual machine piping does not affect the strength and soundness of the piping after the sample is collected, and therefore affects the use and operation of the piping after sampling. A sample that is small enough to never occur and has a size that can be called a minute sample is used.

Here, if creep damage progresses in the piping, damage distribution generally occurs in the wall thickness direction, but large-diameter pipes of actual machines such as improved 9Cr-1Mo steel pipes (specifically, the diameter is about 400 to 1000 mm). In the case of (Piping), as long as the material and operation are within the normal range, it is considered that creep damage may progress in the welded part, but creep damage hardly progresses in the base metal part. Therefore, in the case of the base material of the pipe, the creep characteristics are generally uniform in the wall thickness direction, and the creep characteristics of the entire pipe should be evaluated by analyzing and testing the sample collected from the vicinity of the outer surface. Is considered possible. However, it is considered that the creep characteristics are different from other places due to decarburization etc. just below the outer surface of the pipe.

In relation to the above, the inventor observed the structure of samples collected from the base material of various improved 9Cr-1Mo steel pipes (particularly large diameter pipes) that were used for a long time in 600 ° C class thermal power plants. As a result of conducting chemical composition, hardness measurement, void observation, and standard creep test in the wall thickness direction, an altered layer is formed within a range of about 0.2 mm from the surface, but inside it, the mother of the pipe is formed. It was found that the creep characteristics of the material are almost constant.

From the above, for example, for the main steam pipes and high-temperature reheat steam pipes (particularly large-diameter pipes) of thermal power plants, samples taken from the part excluding the area of about 1 mm from the outer surface of the base material of the pipes. It is preferable that microscopic structure analysis (treatment of S2 described below) and small punch creep test (treatment of S4 described below) are performed using the above, thereby appropriately evaluating the creep characteristics of the base metal of the pipe. It is possible to do.

In the treatment of S1, a disk-shaped sample having a diameter of 3 mm and a thickness of 0.15 mm is collected from the base material of the actual machine piping as a sample for microstructure analysis in the treatment of S2. As a test piece (that is, SP test piece) for the small punch creep test in the treatment of S4, for example, a disk-shaped sample having a diameter of 8 mm and a thickness of 0.5 mm is collected.

In the processing of S1 of the material life evaluation method, further, as a procedure when the material life evaluation program 17 is executed, in other words, as a processing in the material life evaluation device 10, the base material of the pipe from which the sample is taken is taken. The value Tu [° C.] of the operating temperature and the value σu [MPa] of the operating stress in the actual machine and the value tu [hour] of the time used for the operating temperature and the operating stress are input via the input unit 13. The input value is stored in the memory 15.

Next, the microstructure of the sample collected in the treatment of S1 is analyzed (S2).

In the treatment of S2, the microstructure of the sample for microstructure analysis collected in the treatment of S1 is analyzed, and the number density [μm- ² ] of the vanadium-based precipitate is measured.

Specifically, for example, a transmission electron microscope (TEM) is used to analyze the microscopic tissue, and the number density [μm- ² ] of the vanadium-based precipitate of the sample is measured.

In the present embodiment, the value of the number density of vanadium-based precipitates ρu [μm ^-2 ] for the sample for microstructure analysis collected in the treatment of S1 is input via the input unit 13, and the input value is input. It is stored in the memory 15.

Subsequently, the creep characteristics are evaluated based on the result of the analysis of the microstructure in the treatment of S2 (S3).

In the treatment of S3, the creep characteristics (in other words, creep rupture characteristics) in the long-term region of the base material sample having the properties found by the treatment of S2 are estimated by referring to the database 21 of the microstructure. Will be done.

Specifically, first, as a preparation for evaluation, an analysis sample related to the data accumulated in the microstructure database 21 (specifically, the base material of the improved 9Cr-1Mo steel pipe used for a long time). ) The initial creep life is estimated for each (S3-1).

The initial creep life of the sample for analysis is estimated by, for example, the following procedure (referred to as "Procedure A") (Masatsugu Yaguchi et al. "Creep strength of improved 9Cr-1Mo steel welded joint in the region over 100,000 hours". ,, Joint Symposium on High Temperature Intensity and Fracture Mechanics, 55th Symposium on High Temperature Intensity, 18th Symposium on Fracture Mechanics, Proceedings, 118, pp. 119-123, 2017).

<Procedure A-1>
Regression is performed by the Larson Miller parameter method for the data of the standard creep test for each analytical sample, and the coefficients and constants in the regression equation are determined.

<Procedure A-2>
The creep rupture time (that is, the above-mentioned actual machine operating conditions) under the conditions (specifically, temperature, circumferential stress) in which each analytical sample is subjected to the actual machine operation using the determined regression coefficient / constant corresponds to the actual machine operating conditions. "Remaining creep life") is calculated. The circumferential stress is calculated by using an average diameter formula corresponding to a pipe shape such as a straight pipe or an elbow, based on the dimensions of the pipe and the operating stress during actual operation. In addition, the operating temperature and operating stress in the actual machine are known as information associated with each of the combination data for each analysis sample.

<Procedure A-3>
The value obtained by adding the calculated "remaining creep life" to the usage time of the actual machine is defined as the "initial creep life" of each analytical sample under the operating conditions of the actual machine. The usage time in the actual machine is known as information associated with each of the combination data for each analysis sample.

In the above estimation method, it is a precondition that the Robinson's rule and the linear damage rule are satisfied. According to the above estimation method, the time required for the standard creep test is shortened by the amount of damage accumulated in the actual machine.

Here, if the standard creep test is not performed at the stress level applied during actual machine operation and the stress conditions applied during actual machine operation are targeted for regression, excessive stress extrapolation results in inappropriate regression. It may end up. In such a case, in order to ensure the accuracy of the regression, the initial creep life under the conditions provided during the actual operation may be estimated by the following procedure (referred to as "procedure B") (referred to as "procedure B"). Masatsugu Yaguchi et al. "Estimation of creep strength of improved 9Cr-1Mo steel welded joints in the region over 100,000 hours" (supra).

<Procedure B-1>
For each analytical sample, the residual creep life corresponding to the temperature To [° C.] and the stress σo [MPa] is specified (specifically, for example, the temperature To = 650 [° C.] and the stress σo = 60 [MPa]. ] Etc.). Specifically, for each sample for analysis, the experimental value is used for those with experimental data at stress σo, and for those without experimental data at stress σo, the stress is converted to stress σo by regression by the Larson Miller parameter method. The corresponding residual creep life is calculated.

<Procedure B-2>
Assuming that the linear damage rule holds, the following equation 1 holds.
(Number 1) tx / X + ty / Y = 1
Here,
X: Operating temperature in the actual machine, initial life of the sample for analysis under operating stress,
Y: Initial life of the sample for analysis at temperature To [° C], stress σo [MPa],
tx: Usage time of the sample for analysis on the actual machine,
ty: Represents the remaining life of the analytical sample corresponding to the temperature To [° C] and the stress σo [MPa], respectively.

Regarding Equation 1, the usage time tx in the actual machine is known as information associated with each of the combination data for each analysis sample, and the remaining life ty is known as a result of the processing in the above <Procedure B-1>. be.

<Procedure B-3>
The creep life due to the average characteristics of the base material portion of the new material is used as the values of X and Y, and the ratio k of X: Y in Equation 1 (that is, k = X / Y) is calculated. The operating temperature and operating stress in the actual machine are known as information associated with each of the combination data for each analysis sample.

The creep life depending on the average characteristics of the base metal part of the new material is, specifically, for example, "2015 Data Study Group Base Metal (Plate) Average Characteristics" (K. Kimura et al. "Re-evaluation of Long-term". Values based on Creep Strength of Base Metal of ASME Grade 91 Type Steel, Proc. PVP20166, Vancouver, Canada, PVP2016-63355, 2016) can be used.

<Procedure B-4>
By substituting X = kY into Equation 1, Y, which is the initial creep life of the sample for analysis at a temperature To [° C.] and a stress σo [MPa], is calculated.

According to the above <Procedure B-1> to <Procedure B-4>, the creep life initially possessed by the analysis sample is calculated in consideration of the influence during use of the actual machine.

In the present embodiment, the precipitate reflecting unit 11a of the control unit 11 determines the number density of vanadium-based precipitates for each base material as an analysis sample from the database 21 of the microstructure of the data server 20 and the result of the standard creep test. The combination data is read and the initial creep lifetime for each analytical sample is estimated by the above procedure A or B.

At this time, if necessary, an appropriate temperature range (in other words, a temperature division) is taken into consideration when evaluating the creep characteristics / creep life of the material, and then stored in the memory 15 in the processing of S1. The operating temperature value Tu [° C.] in the actual machine is referred to, and only the combination data corresponding to the operating temperature value Tu [° C.] in the actual machine is used among the combination data stored in the database 21 of the microstructure. You may do so.

Then, the number density, temperature, stress of the vanadium-based precipitate, and the initial creep life (estimated value) at the temperature and stress for each analysis sample related to the data accumulated in the microstructure database 21 by the precipitate reflection unit 11a. ) Is stored in the memory 15.

Subsequently, as a preparation for evaluation, the correlation between the number density of vanadium-based precipitates and the creep characteristics (specifically, the precipitate reflection coefficient in this case) is calculated (S3-2).

Specifically, the precipitate reflecting unit 11a reads the combination data of the number density of vanadium-based precipitates stored in the memory 15 and the initial creep lifetime (estimated value) in the processing of S3-1.

At this time, if necessary, an appropriate stress range (in other words, stress classification) is taken into consideration when evaluating the creep characteristics / creep life of the material, and then stored in the memory 15 in the processing of S1. The working stress value σu [MPa] in the actual machine is referred to, and only the combination data corresponding to the working stress value σu [MPa] in the actual machine is used among the combination data stored in the memory 15. Is also good.

Subsequently, the precipitate reflection unit 11a calculates the precipitate reflection coefficient K by dividing the initial creep life (estimated value) read from the memory 15 by the basic value of the creep life for the base material portion of the new material. As a result, combination data of the number density of vanadium-based precipitates and the precipitate reflection coefficient K is generated.

As the basic value of the creep life of the base material of the new material, the creep life of the base material based on the average characteristics is used without considering the amount of vanadium-based precipitates. As the basic value of the creep life of the base material portion of the new material, for example, a value based on "2015 Data Study Group Base Material (Plate) Average Characteristics" (supra) can be used.

Further, the precipitate reflection unit 11a calculates the correlation between the number density of the vanadium-based precipitate and the precipitate reflection coefficient K by using the combination data generated as described above.

For the calculation of the correlation between the two, a regression equation such as the following equation 2 is assumed, and the regression coefficient / constant (specifically, a and b in the equation 2) is, for example, regression analysis. It is done by being estimated by.

(Number 2) K = a × ρ + b
Here, K: precipitate reflection coefficient (however, K ≧ 0),
ρ: Number density of vanadium-based precipitates [μm ^-2 ],
a, b: Regression coefficients and constants, respectively.

The correlation between the number density of the vanadium-based precipitate and the precipitate reflection coefficient K is the value of the number density ρ after the range of the value of the number density ρ of the vanadium-based precipitate (in other words, the division) is set. It may be calculated for each range / division of, or when the value of the number density ρ is in a predetermined range, the precipitate reflection coefficient K may be a constant value.

Then, the precipitate reflection coefficient is calculated using the result of the analysis of the microstructure in the treatment of S2 and the correlation calculated in the treatment of S3-2 (S3-3).

Specifically, the precipitate reflecting unit 11a applies the value ρu of the number density of the vanadium-based precipitates stored in the memory 15 in the processing of S2 to Equation 2 (in other words, substitutes), and the precipitates. The value Ku of the reflection coefficient is calculated.

Then, the value Ku of the calculated precipitate reflection coefficient is stored in the memory 15 by the precipitate reflection unit 11a.

Further, a small punch creep test is performed using the SP test piece collected in the treatment of S1 (S4).

In the treatment of S4, an SP test piece collected together with a sample for microstructure analysis in the treatment of S1 is used to perform a creep test by a small punch, and the creep characteristics by the small punch creep test are grasped.

In the creep test using the small punch (SP), after confirming the operating temperature value Tu [° C] and the operating stress value σu [MPa] in the actual machine, for example, the device shown in FIG. 4 is used and the following test is performed. It is done according to the conditions.
<Conditions for creep test>
Temperature: Tu ℃
Load: σu MPa
Atmosphere: High-purity argon (Ar) gas (99.99%), 150 ml / min

Then, the values (specifically, test temperature, test stress, rupture time, etc.) related to the result of the creep test by the small punch for the SP test piece collected in the processing of S1 are input via the input unit 13, and the said The input value is stored in the memory 15.

Subsequently, the creep characteristics are evaluated based on the result of the small punch creep test in the treatment of S4 (S5).

In the treatment of S5, the creep characteristics (in other words, creep rupture characteristics) in the long-term region of the base metal test piece having the properties found by the treatment of S4 are estimated by referring to the database 22 of the creep test. Will be done.

Specifically, first, as a preparation for evaluation, the estimation formula of the remaining life based on the result of the creep test by the small punch is calculated (S5-1).

Specifically, the long-term behavior reflection unit 11b of the control unit 11 reads the data of the result of the creep test by the small punch stored in the memory 15 in the processing of S4.

At this time, if necessary, an appropriate temperature range (in other words, a temperature division) is taken into consideration when evaluating the creep characteristics / creep life of the material, and then stored in the memory 15 in the processing of S1. The operating temperature value Tu [° C.] in the actual machine is referred to, and only the data corresponding to the operating temperature value Tu [° C.] in the actual machine is used among the data of the small punch creep test results stored in the memory 15. You may do so.

At this time, if necessary, an appropriate stress range (in other words, stress classification) is taken into consideration when evaluating the creep characteristics / creep life of the material, and then stored in the memory 15 in the processing of S1. The working stress value σu [MPa] in the actual machine is referred to, and only the data corresponding to the working stress value σu [MPa] in the actual machine is used among the data of the small punch creep test results stored in the memory 15. You may do so.

Subsequently, the long-term behavior reflection unit 11b calculates the estimation formula of the remaining life using the data of the result of the small punch creep test read by the above.

For the calculation of the remaining life estimation formula, a regression formula such as the following formula 3 is assumed, and the regression coefficient / constant (specifically, in formula 3, a ₀ , a ₁ , a ₂ , C) is estimated, for example, by multiple regression analysis.

ここに、
ｔr：余寿命の推定値〔時間〕
Ｔ：温度〔℃〕，
σ：応力〔ＭＰａ〕，
ａ₀，ａ₁，ａ₂，Ｃ：回帰係数・定数 をそれぞれ表す。

Here,
tr: Estimated remaining life [time]
T: Temperature [° C],
σ: Stress [MPa],
a ₀ , a ₁ , a ₂ , C: Regression coefficient / constant.

Subsequently, as a preparation for evaluation, the estimated value of the initial creep life is further calculated using the estimation formula of the remaining life calculated in the process of S5-1 (S5-2).

Specifically, the long-term behavior reflection unit 11b applies the operating temperature value Tu [° C.] and the operating stress value σu [MPa] stored in the memory 15 in the memory 15 in the processing of S1 to Equation 3 (). In other words, it is substituted), and the estimated value tr of the remaining life is calculated.

The estimated remaining life tr calculated by Equation 3, that is, the remaining life when the operating temperature is Tu [° C] and the operating stress is σu [MPa] based on the result of the creep test by the small punch. Is.

Subsequently, the long-term behavior reflection unit 11b substitutes the calculated estimated value tr of the remaining life into the following mathematical formula 4, and calculates the estimated value ti of the initial creep life of the base material portion of the material used. The time value tu [time] used at the operating temperature Tu [° C.] and the operating stress σu [MPa] in the actual machine is known as information associated with each of the combination data for each analysis sample.

(Number 4) ti = tu + tr
Here,
ti: Estimated initial creep life of the base material used [time],
tu: Time used at operating temperature Tu [° C] and operating stress σu [MPa],
tr: Estimated remaining life calculated by formula 3 [time]
Represents each.

Then, the long-term behavior reflection coefficient is calculated using the estimated value of the initial creep life of the base material portion of the base material used in the process of S5-2 (S5-3).

Specifically, the long-term behavior reflection unit 11b applies the estimated value ti of the initial creep life calculated by the processing of S5-2 to the following equation 5 (in other words, it is substituted), and the long-term behavior. The value Lu of the reflection coefficient is calculated.

(Number 5) L = ti / ts
Here, L: long-term behavior reflection coefficient,
ti: Estimated initial creep life of the base material used [time],
ts: Basic value of creep life for the base material of the new material [time]
Represents each.

As the basic value ts of the creep life of the base material portion of the new material in Equation 5, the creep life of the base material portion based on the average characteristics is used. As the basic value ts of the creep life for the base material portion of the new material, for example, a value based on "2015 Data Study Group Base Material (Plate) Average Characteristics" (supra) can be used.

Then, the value Lu of the calculated long-term behavior reflection coefficient is stored in the memory 15 by the long-term behavior reflection unit 11b.

Next, the creep characteristics of the base metal portion are evaluated based on the results of the evaluation of the creep characteristics related to the precipitate in the treatment of S3 and the results of the evaluation of the creep characteristics related to the long-term behavior in the treatment of S5 (S6). ..

In the treatment of S6, a coefficient representing the creep characteristic of the base material portion of the actual machine piping is specified based on the precipitate reflection coefficient calculated by the treatment of S3 and the long-term behavior reflection coefficient calculated by the treatment of S5.

Specifically, the characteristic evaluation unit 11c of the control unit 11 reads the value Ku of the precipitate reflection coefficient stored in the memory 15 in the processing of S3, and reflects the long-term behavior stored in the memory 15 in the processing of S5. The coefficient value Lu is read.

Subsequently, the characteristic evaluation unit 11c specifies the smaller value of the read precipitate reflection coefficient value Ku and the long-term behavior reflection coefficient value Lu.

Then, the characteristic evaluation unit 11c stores the value specified by the above in the memory 15 as the value Xu of the base material portion characteristic coefficient.

Next, based on the result of the evaluation of the creep characteristic of the base metal portion in the treatment of S6, the creep characteristic of the welded portion is evaluated as a procedure related to the treatment related to the welded portion (S7).

In the processing of S7, the creep rupture characteristics of the welded portion in the actual machine piping having the value Xu of the base material portion characteristic coefficient specified by the processing of S6 for the base metal portion are estimated by referring to the database 23 of the creep rupture characteristics. Will be done.

Specifically, first, as a preparation for evaluation, an analysis sample related to the data accumulated in the creep break property database 23 (specifically, the base material of the improved 9Cr-1Mo steel pipe used for a long time). And the welded joint), the initial creep life is estimated (S7-1).

The initial creep lifetime of the analytical sample is estimated by "Procedure A" or "Procedure B" described in connection with the treatment of S3-1.

Specifically, the result of the standard creep test of the base metal part for each pipe as an analysis sample and the standard creep of the welded joint part are obtained from the creep break characteristic database 23 of the data server 20 by the life calculation unit 11d of the control unit 11. Combined data with the test results is read and procedure A or procedure B estimates the initial creep life for each analytical sample (ie, the base metal and welded joint of the same pipe).

At this time, if necessary, an appropriate temperature range (in other words, a temperature division) is taken into consideration when evaluating the creep characteristics / creep life of the material, and then stored in the memory 15 in the processing of S1. The operating temperature value Tu [° C.] in the actual machine is referred to, and only the combination data corresponding to the operating temperature value Tu [° C.] in the actual machine is used among the combination data stored in the creep break characteristic database 23. You may do so.

Then, by the life calculation unit 11d, the temperature, stress, and the base material portion at the temperature and stress for each analysis sample (in other words, related to the same pipe) related to the data accumulated in the creep rupture characteristic database 23. The combination data of the initial creep life (estimated value) and the initial creep life (estimated value) of the welded portion is stored in the memory 15.

Subsequently, as a preparation for evaluation, the correlation between the initial creep life of the base metal portion and the initial creep life of the welded portion is further calculated (S7-2).

Specifically, the life calculation unit 11d provides combined data of the initial creep life (estimated value) of the base metal portion and the initial creep life (estimated value) of the welded portion stored in the memory 15 in the processing of S7-1. Loaded.

At this time, if necessary, an appropriate stress range (in other words, stress classification) is taken into consideration when evaluating the creep characteristics / creep life of the material, and then stored in the memory 15 in the processing of S1. The working stress value σu [MPa] in the actual machine is referred to, and only the combination data corresponding to the working stress value σu [MPa] in the actual machine is used among the combination data stored in the memory 15. Is also good.

Subsequently, the life calculation unit 11d divides the initial creep life (estimated value) of the base metal portion read from the memory 15 by the basic value of the creep life of the base metal portion of the new material, and the initial creep life of the welded portion. (Estimated value) is divided by the basic value of creep life for the weld of the new material, which produces combined data of the normalized initial creep life of the base metal and the initial creep life of the weld.

As the basic value of the creep life of the base material portion of the new material, the creep life of the base metal portion based on the average characteristics is used. As the basic value of the creep life of the base material portion of the new material, for example, a value based on "2015 Data Study Group Base Material (Plate) Average Characteristics" (supra) can be used.

Further, as the basic value of the creep life of the welded portion of the new material, the creep life of the welded portion depending on the average characteristic is used. Specific examples of the basic value of creep life for welded parts of new materials include, for example, "2015 Data Study Group Welded Joint Average Characteristics" (M. Yaguchi et al., "Re-evaluation of Long-term Creep Steel of Welded Joint of ASME". Values based on "Grade 91 Type Steel", Proc. PVP20166, Vancouver, Canda, PVP2016-63316, 2016) can be used.

Further, the life calculation unit 11d calculates the correlation between the initial creep life of the base metal portion and the initial creep life of the welded portion by using the combination data generated as described above.

For the calculation of the correlation between the two, a regression equation such as the following equation 6 is assumed, and the regression coefficient / constant (specifically, p, q, r in the equation 6) is, for example. It is done by estimating by regression analysis.

(Number 6) Y = pX ² + qX + r
Here, Y: Initial creep life of the normalized weld (where Y ≧ 0),
X: Initial creep life of standardized base metal,
p, q, r: Regression coefficient / constant.

The correlation between the initial creep life of the base metal part and the initial creep life of the welded part is the range / classification of the value of X after the range of the value of X (in other words, the classification) is set. It may be calculated separately, or Y may be a constant value when the value of X is in a predetermined range.

Equation 6 is a formula that expresses the relationship between the life of the base metal portion and the welded portion in the same pipe in a standardized state, in other words, the creep characteristics of the base metal portion and the welded portion in the same pipe. It can be said that it is an equation expressing the relationship with the creep characteristic, and therefore, it is an equation that converts the characteristic coefficient of the base metal portion into the characteristic coefficient of the welded portion. For this reason, Y in Equation 6 is referred to as a "welded portion characteristic coefficient".

Then, the rupture time of the welded portion of the actual piping is estimated by using the result of the evaluation of the creep characteristic of the base metal portion in the treatment of S6 and the correlation calculated in the treatment of S7-2 (S7-3). ).

Specifically, the life calculation unit 11d applies the value Xu of the base material part characteristic coefficient stored in the memory 15 in the processing of S6 to the initial creep life X of the base material part of the equation 6 (in other words, another word). , Substituted), and the value Yu of the weld characteristic coefficient is calculated as the initial creep life Y of the weld.

Further, the life calculation unit 11d substitutes the value Yu of the weld characteristic coefficient calculated above into the following mathematical formula 7 to estimate the fracture time of the weld.

(Number 7) twj = Y × t
Here, twj: breaking time [time] of the welded part,
Y: Welded part characteristic coefficient,
t: Basic value of creep life for welded parts of new material [time]
Represents each.

As the basic value of the creep life of the welded portion of the new material in Equation 7, the creep life of the welded portion based on the average characteristic is used. As the basic value of the creep life of the welded portion of the new material, for example, a value based on "2015 Data Study Group Welded Joint Average Characteristics" (supra; formula 8 below) can be used.

ここに、 ｔ：新材の溶接部に関するクリープ寿命の基本値〔時間〕，
Ｔ：温度〔℃〕，
σ：応力〔ＭＰａ〕 をそれぞれ表す。

Here, t: the basic value of creep life for the welded part of the new material [time],
T: Temperature [° C],
σ: Represents stress [MPa].

In the processing of S1, the operating temperature value Tu [° C.] and the operating stress value σu [MPa] stored in the memory 15 are referred to, and the operating temperature value Tu is substituted into T of the equation 8 and σ. By substituting the working stress value σu, the creep life of the welded portion of the new material with respect to these working temperatures and working stresses is calculated.

The value of the fracture time twj of the welded portion calculated by Equation 7 is the fracture time [time] of the welded joint of the pipe in the actual machine in which the sample was taken from the base metal portion in the processing of S1, and the fracture time in the actual machine is used. By subtracting the time (tu [hour]) used for the operating temperature (Tu [° C.]) and the operating stress (σu [MPa]), the above-mentioned operating temperature (Tu [° C.]) and operating stress (σu [σu]). The remaining life [time] of the welded joint of the pipe in the actual machine corresponding to MPa]) is calculated.

Then, the calculated breaking time [time] of the welded joint of the pipe in the actual machine and the remaining life [time] of the welded joint are displayed on the display unit 14 or stored in the storage unit 12 as a data file. Then, the control unit 11 ends the evaluation of the life of the pipe from which the sample was taken in the processing of S1.

According to the material life evaluation method, material life evaluation device, and material life evaluation program configured as described above, the creep characteristics of the base material are determined by using the sample collected from the base material of chrome steel. Since the creep life (in other words, creep breaking characteristics) of the welded portion of the chrome steel is evaluated based on the evaluation results, the creep breaking characteristics (in other words, heat) peculiar to each material / member are evaluated. By considering the difference) in the life evaluation of the welded portion of the material / member, it is possible to evaluate the life reflecting the unique creep breakage characteristics of the welded portion of each material / member. Therefore, it is possible to improve the estimation accuracy of the life evaluation by performing the life evaluation according to the substance of each material / member, and it is possible to improve the reliability of the life evaluation. In particular, in the conventional evaluation of remaining life, 99% reliability lower limit characteristics are uniformly used for all pipes, which tends to give conservative results, whereas in the present invention, each material / member is actually used. Since the material properties corresponding to the strength of the above are used, it becomes possible to give more rational evaluation results.

Although the above-described embodiment is an example of a preferred embodiment of the present invention, the embodiment of the present invention is not limited to the above-mentioned embodiment, and the present invention is not limited to the above-mentioned embodiment and does not deviate from the gist of the present invention. The invention can be modified in various ways.

For example, in the above-described embodiment, the material life evaluation method, the material life evaluation device, and the material life evaluation program according to the present invention are applied to the evaluation of the creep life of the welded portion / welded joint of the improved 9Cr-1Mo steel pipe. However, the application of the present invention is not limited to the welded joint of the improved 9Cr-1Mo steel pipe. The present invention can be widely applied to general chromium steel materials / members containing, for example, about 9 to 12 mol% of chromium (Cr) and having a base material portion and a welded portion.

Further, in the above-described embodiment, in the treatment of S6, the smaller of the value Ku of the precipitate reflection coefficient and the value Lu of the long-term behavior reflection coefficient is used as the value Xu of the base material portion characteristic coefficient. The method for determining the value Xu of the base material characteristic coefficient based on the value Ku of the material reflection coefficient and the value Lu of the long-term behavior reflection coefficient is not limited to that in the above-described embodiment, and is, for example, the value Ku of the precipitate reflection coefficient. And the average value of the value Lu of the long-term behavior reflection coefficient may be used as the value Xu of the base material part characteristic coefficient, and further, the value Xu of the base material part characteristic coefficient is the value Ku of the precipitate reflection coefficient. It may be determined in any way as long as it is in the range between the value of the long-term behavior reflection coefficient Lu and the value Lu.

The material life evaluation method, the material life evaluation device, and the material life evaluation program according to the present invention can accurately evaluate the material life, and therefore, for example, material engineering, structural engineering, and structure design practice. High utility value in fields such as maintenance and management practices.

10 Computer / material life evaluation device 11 Control unit 11a Precipitate reflection unit 11b Long-term behavior reflection unit 11c Characteristic evaluation unit 11d Life calculation unit 12 Storage unit 13 Input unit 14 Display unit 15 Memory 17 Evaluation program 20 Data server 21 Microscopic organization Database 22 Creep test database 23 Creep rupture characteristics database

Claims (6)

For the sample collected from the base material of chrome steel, the precipitate reflection coefficient corresponding to the number density of vanadium-based precipitates in the sample is calculated based on the correspondence between the number density of vanadium-based precipitates and the result of the standard creep test. The long-term behavior reflection coefficient corresponding to the result of the small punch creep test of the test piece is based on the correspondence between the result of the small punch creep test and the result of the standard creep test for the test piece collected from the base material portion of the chrome steel. Calculated, the base metal part characteristic coefficient is specified based on the value of the precipitate reflection coefficient and the value of the long-term behavior reflection coefficient, and the result of the standard creep test of the base material part and the result of the standard creep test of the welded part. The value of the welded portion characteristic coefficient corresponding to the value of the base metal portion characteristic coefficient is specified based on the correspondence of the above, and the break time of the welded portion of the chrome steel is calculated using the value of the welded portion characteristic coefficient. A method for evaluating material life, which is characterized by the fact that. The method for evaluating a material life according to claim 1, wherein the chromium steel is an improved 9Cr-1Mo steel. A means for calculating the precipitate reflection coefficient corresponding to the number density of vanadium-based precipitates in the sample based on the correspondence between the number density of vanadium-based precipitates and the result of the standard creep test for the sample collected from the base metal portion of the chrome steel. Long-term behavior reflection coefficient corresponding to the result of the small punch creep test of the test piece based on the correspondence between the result of the small punch creep test and the result of the standard creep test for the test piece collected from the base material portion of the chrome steel. A means for calculating the base metal part characteristic coefficient based on the value of the precipitate reflection coefficient and the value of the long-term behavior reflection coefficient, a standard creep test result of the base metal part, and a standard of the welded part. Based on the correspondence with the result of the creep test, the value of the welded portion characteristic coefficient corresponding to the value of the base metal portion characteristic coefficient is specified, and the break time of the welded portion of the chrome steel is specified by using the value of the welded portion characteristic coefficient. A material life evaluation device characterized by having a means for calculating. The material life evaluation device according to claim 3, wherein the chromium steel is an improved 9Cr-1Mo steel. A process of calculating the precipitation reflection coefficient corresponding to the number density of vanadium-based precipitates in the sample based on the correspondence between the number density of vanadium-based precipitates and the result of the standard creep test for the sample collected from the base metal part of the chrome steel. Long-term behavior reflection coefficient corresponding to the result of the small punch creep test of the test piece based on the correspondence between the result of the small punch creep test and the result of the standard creep test for the test piece collected from the base material portion of the chrome steel. The process of calculating the base metal part characteristic coefficient based on the value of the precipitate reflection coefficient and the value of the long-term behavior reflection coefficient, the process of specifying the base metal part characteristic coefficient, the result of the standard creep test of the base material part, and the standard of the welded part. Based on the correspondence with the result of the creep test, the value of the welded portion characteristic coefficient corresponding to the value of the base metal portion characteristic coefficient is specified, and the break time of the welded portion of the chrome steel is specified by using the value of the welded portion characteristic coefficient. A material life evaluation program characterized by having a computer perform the process of calculating. The material life evaluation program according to claim 5, wherein the chromium steel is an improved 9Cr-1Mo steel.

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