JP2010164430A - Method and apparatus for evaluating creep damage of metallic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal material creep damage evaluation method and a creep damage evaluation apparatus for highly accurately and stably evaluating the appropriateness of the continuous use of metallic materials. <P>SOLUTION: The correlation between the amount of creep strain and a crystal orientation distribution of a test material is previously determined. A crystal orientation distribution of a material to be examined is measured and fitted in the previously determined correlation to estimate the amount of creep strain of the material to be examined. By comparing the estimated amount of creep strain of the material to be examined with the amount of strain at which the test material reaches an accelerating creep stage, the appropriateness of the continuous use of the material to be examined is determined. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a creep damage evaluation method and a creep damage evaluation apparatus for a metal material constituting an equipment component such as a gas turbine, for example.

  Conventionally, heat-resistant steel, Ni-base heat-resistant alloys, and the like have been used as metal materials that constitute equipment parts such as gas turbines. Examples of a method for evaluating the creep damage of such a metal material include, for example, an A-parameter method for evaluating voids on grain boundaries generated in the creep process, a metallographic method for evaluating from precipitate shape change, and an equipment part. There are a mechanical test method in which a creep test piece is collected from a part of the sample and a creep test is performed for evaluation, a hardness method in which the hardness is evaluated from a change in material hardness, an electrical resistance method in which an evaluation is performed from a change in electrical resistance, and the like.

  However, the evaluation method described above has the following problems. The A parameter method can only be applied at the final stage of the lifetime in which creep voids are generated and grow, and cannot be applied to materials that are unlikely to generate creep voids. The metallographic method cannot be applied to materials used in an environment where precipitation changes are unlikely to occur (temperature range where precipitation changes hardly occur). In the case of a material used in a sufficiently high temperature range), the measurement error becomes large, and furthermore, it cannot be applied to a material in which no precipitate is generated. The mechanical test method requires a long time for the test, and the collection of the test piece from the equipment part has many geometric restrictions, and it may be difficult to collect the test piece from the site where the creep damage is most severe. In the hardness method, a measurement error becomes large in a material having a small change in hardness with respect to the deformation amount of the material. The electrical resistance method is sensitive to changes in the resistance value, is susceptible to noise, and tends to increase measurement errors.

  Therefore, in recent years, the following creep damage evaluation method has been proposed. In this evaluation method, first, a material life acceleration test (for example, fatigue test) of a test material of a specific material is performed in advance, and crystal orientation difference data for a certain material life progress is collected in advance. A master curve representing the relationship between the degree of progress and the crystal orientation difference is created. Measure the crystal orientation difference between the test material and the test material of the same kind as the test material where the material life has actually progressed, and assign this value to the master curve to predict the progress of the material life of the test material and break it. The remaining remaining life is predicted (for example, refer to Patent Document 1).

  In this evaluation method, the crystal orientation difference in the crystal grains is measured using an EBSP (Electron Back-Scatter Diffraction Pattern) method, and the KAM (Karnel Average Misorientation) value derived from the value is used as the material. It is a method of associating with the progress of life.

  However, the above evaluation method has the following problems. In other words, the crystal orientation angle difference between any two points in the grain is only about a few degrees even in the material at the end of life, so that not only a sufficient evaluation accuracy can be obtained only at the end of life of the material, but also measurement errors. It is difficult to ensure the stability and reliability of data.

JP 2004-3922 A

  The present invention has been made in response to the above-described conventional circumstances, and an object of the present invention is to evaluate a creep damage of a metal material capable of evaluating whether or not the metal material can be continuously used with high accuracy and stability, and It is to provide a creep damage evaluation apparatus.

  One aspect of the creep damage evaluation method for a metal material according to the present invention is a creep damage evaluation method for a metal material for evaluating the damage degree of a metal material that has undergone creep damage. A step of obtaining a correlation with the orientation distribution in advance, a step of measuring the crystal orientation distribution of the investigation material for creep damage evaluation, and the creep orientation amount and the crystal orientation distribution of the measured crystal orientation distribution of the investigation material. A step of estimating a creep strain amount of the investigation material by applying to the correlation with the step, a step of previously obtaining a correlation between a strain amount reaching the acceleration creep region and a creep test stress using the test material, and the acceleration The investigation material reaches the accelerated creep region from the correlation between the amount of strain reaching the creep region and the creep test stress and the stress that the investigation material receives. A step of estimating the amount of strain, and a step of evaluating the degree of damage of the investigation material by comparing the estimated amount of creep strain of the investigation material with the amount of strain estimated by the investigation material reaching the accelerated creep region It was characterized by comprising.

  One aspect of the creep damage evaluation apparatus for a metal material according to the present invention is a creep damage evaluation apparatus for a metal material that evaluates the degree of damage of a metal material that has undergone creep damage, and is quantified as the amount of creep strain in the test material. A database containing first data representing a correlation with the crystal orientation distribution, and containing second data representing a correlation between the amount of strain reaching the accelerated creep region in the test material and the creep test stress; Crystal orientation distribution measurement means for measuring the crystal orientation distribution of the investigation material, crystal orientation distribution quantification means for quantifying the crystal orientation distribution of the investigation material measured by the crystal orientation distribution measurement means, and quantification of the investigation material A creep strain amount estimating means for applying a converted crystal orientation distribution to the first data to estimate a creep strain amount of the investigation material; Accelerated creep region reaching strain amount estimation means for estimating an accelerated creep region reaching strain amount at which the investigation material reaches the accelerated creep region from the second data and the stress received by the investigation material, and the estimated investigation And a judgment means for evaluating the degree of damage of the investigation material by comparing the creep strain amount of the material with the estimated amount of strain reaching the accelerated creep region.

  ADVANTAGE OF THE INVENTION According to this invention, the creep damage evaluation method and creep damage evaluation apparatus of a metal material which can evaluate the possibility of continuous use of a metal material stably with high precision can be provided.

The flowchart which shows the procedure of the creep damage evaluation method of one embodiment of this invention. The graph which shows the relationship between crystal orientation distribution parameter P _{<101>, 15} and a creep life consumption rate. The graph which shows the relationship between a GAM value and a creep life consumption rate. The graph which shows the relationship between crystal orientation distribution parameter P _{<101>, 15} and a creep distortion amount. The graph which shows the relationship between a GAM value and the amount of creep strain. The graph which shows the stress dependence of a creep rate-strain diagram. The schematic diagram which shows the method of estimating the distortion | strain amount which reaches | attains an acceleration creep area on the conditions equivalent to a real machine from experimental data. The block diagram which shows the structure of the creep damage evaluation apparatus of one embodiment of this invention.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a creep damage evaluation method and creep damage evaluation apparatus for a metal material according to the present invention will be described with reference to an example of creep life evaluation of a part mainly made of a solid solution strengthened Ni-base heat-resistant superalloy having a face-centered cubic structure. Will be described with reference to FIG.

  In the present invention, the remaining life (damage degree) of a material is evaluated by correlating the crystal orientation of the material and its change with the amount of damage to the material. The crystal orientation can be measured by the EBSP method. The EBSP method is a method of measuring a crystal orientation at an arbitrary point of a material by analyzing a Kikuchi line pattern in SEM (scanning electron microscope) reflection electron diffraction. A fully automatic analysis system for crystal orientation using this method, OIM (ORIENTATION IMAGING MICROSCOPY, TM) has been developed. Usually, the crystal orientation information of the entire observation surface is obtained as plane information by measuring the crystal orientation at each of a large number of measurement points (usually tens of thousands to hundreds of thousands) regularly arranged at intervals of several μm. be able to. Recently, OIM has been popularized with the improvement of computing power of computers.

The present inventors investigated in detail the relationship between the progress of creep damage and the change in crystal orientation using a solid solution strengthened Ni-base heat-resistant superalloy having a face-centered cubic structure (Hastelloy X: Hastelloy is a registered trademark). That is, the crystal orientations of the new material, the creep interrupted material at an arbitrary time, and the creep rupture material were measured by the OIM system. The relevant part of each test material was cut out, subjected to finish polishing and inserted into the SEM, and the crystal orientation distribution viewed from the stress axis direction was measured by OIM. As a result, the crystal orientation distribution parameter P _{<101>, 15} (hereinafter sometimes abbreviated as “crystal orientation distribution parameter P”) obtained by quantifying the measured crystal orientation distribution is shown in the graph of FIG. Shows a good correlation with the creep life consumption rate (ratio of interruption time to creep rupture time). In FIG. 2, the vertical axis represents the crystal orientation distribution parameter P _{<101>, 15} (%), and the horizontal axis represents the creep life consumption rate (%). Further, the ratio of the number of measurement points where the angle between the stress axis and the specific crystal orientation <uvw> is within x ° to the total number of measurement points was defined as the crystal orientation distribution parameter P _{<uvw>, x} .

Further, in the two-dimensional array measurement data, for the kth crystal grain, the orientation difference between all adjacent two points included in the grain is obtained, and the average of these is obtained as the average orientation difference of the kth grain. B _k is _defined , and the k-th crystal grain area is _defined as A _k , the total crystal grain area in the measurement region is defined as A, and a weighted average value of the crystal grain areas is defined as a GAM value. The GAM value is represented by the following formula (1). In the formula (1), m represents the number of crystal grains.

  At this time, the GAM (Grain Average Misorientation) value showed a good correlation with the creep life consumption rate as shown in the graph of FIG. In FIG. 3, the vertical axis indicates the GAM value (deg), and the horizontal axis indicates the creep life consumption rate (%).

Furthermore, the vertical axis represents the crystal orientation distribution parameter P _{<101>, 15} (%), the horizontal axis represents the creep strain amount (%), the graph of FIG. 4, the vertical axis represents the GAM value (deg), and the horizontal axis represents creep. As shown in the graph of FIG. 5 with the amount of strain (%), the crystal orientation distribution parameter P and the GAM value were also found to have a good correlation with the amount of creep strain. From the change mechanism of the crystal orientation distribution parameter P and GAM, it was confirmed that the crystal orientation distribution parameter P and the GAM value are more directly correlated with the amount of creep strain than the creep time. The present invention is based on such knowledge.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a creep damage evaluation method will be described taking a part exposed to a high temperature of a power generation gas turbine as an example.

  First, an evaluation part of a target power plant component is selected. The evaluation part is the part that dominates the life of the part, and is the part with the most severe environment in terms of material that can be grasped from the trend analysis of damage cases of similar parts and temperature / stress analysis by FEM (finite element method) etc. It is.

  Understand the usage environment (temperature / stress) of this part, use the same material as the part concerned, and under conditions that simulate the environment, creep life consumption rate 0% (new material), creep life consumption rate 100% (Fracture material) and test material (creep test material) in the life consumption rate between them are prepared and measured by the EBSP method, as shown in FIGS. 2 to 5, the crystal orientation distribution parameter P or GAM value And data (master curve) showing a correlation between the creep life consumption rate (%) or the creep strain amount. However, in a test that simulates the actual usage environment of parts, it often takes a long time to break.

  Therefore, when creating the master curve, we considered making the conditions of temperature and stress stricter than the actual conditions and adopting the creep condition that the test is completed in a shorter time. The present inventors conducted a creep test in which the temperature and stress were changed, and investigated how the master curve changed. As a result, in both the crystal orientation distribution parameter P and the GAM value, the shape of the master curve with respect to the creep life consumption rate changed greatly when either the test temperature or the stress was changed. On the other hand, it was confirmed that the master curve with respect to the creep strain amount was small even when either the test temperature or the stress was changed, and hardly changed with respect to the change in stress.

  Further, on the low strain side (for example, 10% or less), which is practically important, the dependence on temperature and stress is particularly small. Therefore, when the creep strain amount is used as an index for evaluating creep damage, the creep test conditions for obtaining the master curve may be different from the actual use environment of the parts. That is, the master curve can be obtained in a shorter time by the acceleration test.

  In this case, a master curve for the creep strain amount can be obtained in a shorter period of time by setting the creep test conditions to be the same as the actual part usage environment and setting the stress to a stricter condition. Can do. Further, the creep test conditions may be set to conditions where the temperature and stress are more severe with respect to the actual use environment of the parts.

  At this time, it is desirable to select the stress under the creep test condition within a range in which the creep deformation mechanism does not change with respect to the stress condition of the actual machine. Since the stress of the actual machine assumed here is small, it is desirable to keep the stress under the accelerated test condition within the low stress range. Specifically, it may be selected from stress within a range in which instantaneous plastic strain does not occur when a load is applied in a creep test. If the actual fracture time does not fall within these conditions, the temperature may be raised within a range in which the rate-determining process of creep deformation does not change. Thus, a master curve can be obtained as data indicating the correlation between the crystal orientation distribution parameter P or GAM value and the creep strain amount in a realistic time.

Next, the test piece is cut out from the evaluation part of the target device part, the crystal orientation distribution parameter P _{<u v w>, x} or GAM value is obtained by EBSP measurement, and compared with the master curve, the target part Can be estimated. However, it is not possible to determine whether or not the component can be used continuously (repair or replacement is necessary). Therefore, whether or not the parts can be used continuously (repair / replacement necessity) is determined based on whether or not the evaluation part is in the accelerated creep region.

According to the study by the present inventors, the creep behavior of Hastelloy X is the test stress during the creep test, as shown in the graph of FIG. 6 where the vertical axis represents the creep rate (logarithm) and the horizontal axis represents the amount of creep strain. It varies depending on σ (σ _1-5 ). In FIG. 6, has a _{σ 1 <σ 2 <σ 3} <σ 4 <σ 5. If the amount of strain reaching the accelerated creep region (the amount of strain when showing the minimum creep rate) is ε _a (σ), the relationship between the creep test stress σ and ε _a (σ) is As shown in the graph of FIG. 7, the horizontal axis is ε _a (σ).

Assuming that the stress of the actual machine assumed here is σ ₁ , the relationship between σ and ε _a (σ) on the low stress side at the same temperature as the actual machine is extrapolated to accelerate under the conditions of the actual machine of the member. The amount of strain reaching the creep region can be estimated as ε _a (σ ₁ ). By comparing the estimated ε _a (σ ₁ ) with the creep strain amount of the component evaluated from the master curve, it is possible to determine whether the component can be used continuously (repair / replacement required). It can be performed. That is, for example, when the member has reached the acceleration creep region, continuous use is disabled. FIG. 1 is a flowchart showing the procedure of the creep damage evaluation method for power plant components shown above.

  Next, a more specific example of the creep damage evaluation method according to the present embodiment will be described with reference to FIG.

  The life dominating factors of parts used at high temperatures in actual plants differ depending on the type of parts and the usage environment, so it is necessary to find the part that determines the life for each condition and evaluate the material damage degree at that part. is there. To do so, determine the site where damage should be evaluated by evaluating the actual damage status (e.g., analyzing the tendency of the cracking site) or estimating the temperature / stress distribution obtained from the FEM analysis. (Step S10).

  Next, the temperature / stress condition of the part extracted as a part to be evaluated for damage is specified (step S20). For this purpose, in addition to analysis by FEM or the like, various methods such as evaluation on the degree of change in the metal structure and actual measurement of temperature by a thermocouple are used depending on the situation.

  Next, test conditions for performing a creep test are determined based on the specified temperature / stress conditions (step S31). Then, a creep test is performed according to the test conditions, the crystal orientation distribution of the test material is measured (step S32), the crystal orientation distribution is quantified to obtain the crystal orientation distribution parameter P (step S33), and the crystal orientation distribution A master curve as shown in FIG. 4 is derived as data indicating the correlation between the parameter P and the creep strain amount (step S34). In this case, instead of the crystal orientation distribution parameter P, a master curve based on the GAM value shown in FIG. 5 can be used.

  In order to complete the creep test in a short time when obtaining the master curve, a creep test by an acceleration test can be performed as described above. In general, with respect to the environment in which plant parts are used, the temperature is in the transition creep region, and the stress is in a sufficiently small range relative to the yield strength of the material at that temperature. Therefore, as acceleration test conditions, it is desirable to select the temperature within a range where transition creep occurs, and to select the stress from a low stress range where instantaneous plastic strain does not occur immediately after loading. Needless to say, the material used for the creep test is preferably the same as the material of the target part (composition, manufacturing method, heat treatment conditions, etc.).

  In order to create a master curve, a test piece is cut out from the creep interrupted test material and adjusted as a sample for EBSP measurement. At this time, the cut-out shape may be a cylindrical shape, a rectangular parallelepiped shape, or a wedge shape, but it is desirable that an area of about several mm × several mm is finally obtained as the EBSP measurement surface. This is because if the measurement range is made too small, the number of crystal grains to be measured decreases, and the measurement variation increases. Here, it is desirable to cut out so that the surface perpendicular to the main stress direction becomes the observation surface. However, if this is difficult, the main stress direction should not be lost even after adjustment to the EBSP sample. There is no problem.

  In general, as an EBSP sample, the sample is embedded in a resin and the sample is adjusted by polishing. However, in the EBSP method, it is desirable to use a conductive SEM observation resin in order to measure information on the extreme surface layer of the sample. . This is because it is not necessary to deposit a conductive film (C, Ag, etc.) on the observation surface, which is performed in general SEM observation.

  In addition, since introduction of strain into the surface by polishing causes a slight shift in crystal orientation in the crystal grains, the GAM value and the like are greatly affected. Therefore, it is desirable to perform treatment such as elution of the strained layer on the sample surface using an acid or the like after mirror polishing. However, even if such processing is performed, the GAM value or the like is likely to cause measurement errors due to sample adjustment. Therefore, it is desirable to keep the amount of noise between samples constant by managing to keep the surface pressure and time in polishing constant. On the other hand, in the case of the crystal orientation distribution parameter P, it indicates the ratio of crystal grains in the range of about 15 ° from the specific orientation, which is much higher than an index that measures an angular difference of about 1 ° in general such as a GAM value. Errors and variations are unlikely to occur.

Next, stress dependence evaluation of the creep characteristics of the test material is performed (step S41). The temperature and stress identified in the evaluation region of the plant component, respectively T _1, the sigma _1. The temperature was fixed at T _1, the creep test was carried out in a plurality of stress conditions, determine the amount of strain when reaching the respective acceleration creep zone epsilon _a a _(sigma). Since σ ₁ is generally a small value, this creep test is selected from a larger stress. However, if the stress is too large, the creep test causes instantaneous plastic strain immediately after the load is applied, and the phenomenon occurring in the part no longer reflects (the two points on the high stress side in FIG. 7 are on straight lines with different slopes). is there). That is, in this creep test, it is necessary to set the stress to a value sufficiently smaller than the yield strength of the material at temperature T _{1 so} that instantaneous plastic strain does not occur immediately after loading. Needless to say, the material used for the creep test is preferably the same as the material of the part (composition, manufacturing method, heat treatment condition, etc.).

Based on the correlation between the creep test stress obtained as described above and the amount of strain reaching the accelerated creep region (see FIG. 7), the accelerated creep region is reached under the conditions of temperature T ₁ and stress σ _1. estimating the amount of strain as ε _a (σ ₁₎ (step S42).

  Next, the crystal orientation distribution of the target part is measured (step S51). In the measurement of the crystal orientation distribution, first, a test piece (investigation material) for EBSP measurement is collected from the evaluation part of the target part. At this time, unlike a mechanical test or the like, the test piece may be very small and can be easily collected by a focused ion beam method, electric discharge machining or the like in addition to a cutting grindstone and a grinder. In addition, since the sample collection trace is very small, backfilling by welding and continuous use of the parts are possible depending on the parts. Note that the change in crystal orientation distribution can also be measured by the X-ray diffraction method, and therefore, it is considered possible to perform nondestructive evaluation. In this case, it is desirable to prepare the master curve by measurement using the X-ray diffraction method under the same conditions.

Next, the measured crystal orientation distribution is quantified (step S52). The quantification of the crystal orientation distribution is performed by the crystal orientation distribution parameter P _{<u v w>, x as} described above. Further, as described above, a GAM value can be used instead of the crystal orientation distribution.

Next, the deformation amount (creep strain amount) of the target part is estimated (step S53). Here, by comparing the already obtained master curve with the crystal orientation distribution parameters P _{<u v w>, x} (GAM value when using the GAM value) obtained for the evaluation part, the creep of the part Estimate the amount of strain.

Finally, it is determined whether or not the target part can be continuously used (step S60). In the determination of whether or not continuous use is possible, the creep strain amount of the target part estimated as described above is set as ε _b , which is the strain amount ε _a that reaches the accelerated creep region under the conditions of the temperature T ₁ and the stress σ _1. Compare with (σ ₁ ). At this time, if ε _b <ε _a (σ ₁ ), it is determined that the target part can be used continuously. Conversely, if ε _b ≧ ε _a (σ ₁ ), it is determined that the target part cannot be used continuously. . That is, when the part has reached the acceleration creep region, it is determined that continuous use is not possible, and the member is repaired or replaced.

  Next, a configuration of the creep damage evaluation apparatus 100 according to the present embodiment will be described with reference to FIG.

  The creep damage evaluation apparatus 100 is configured by a computer or the like that executes a program stored in the program database 120 by the control means 130.

  The control means 130 is composed of arithmetic means such as a CPU that executes various arithmetic processes inside, a non-volatile memory such as a ROM that stores system information and the like, and a semiconductor memory such as a RAM that stores information that can be updated. Storage means, and various control operations inside and control means for exchanging information with the outside. The control means 130 executes various information processing in accordance with the input from the input / output interface 140, the contents of the installed program, and the like. , Responsible for controlling each component.

  Further, the creep damage evaluation apparatus 100 includes an input / output interface 140. The input / output interface 140 is configured by a keyboard or a pointing device that is generally provided in a computer or the like. The input / output interface 140 receives character input or selection input by a user or the like and supplies it to the control means 130 or the like. Furthermore, the creep damage evaluation apparatus 100 includes a display unit 160 configured to display predetermined information under the control of the control unit 130, which includes a liquid crystal display, a CRT display, or the like. Moreover, the creep damage evaluation apparatus 100 includes a program database 120, a calculation database 150, and the like that are configured by storage means such as a hard disk.

The calculation database 150 stores data necessary for executing calculations related to creep damage evaluation. For example, data related to various master curves derived by the master curve deriving unit 124 described later (for example, crystal orientation distribution parameter P _{<uvw>, 15} and data _indicating the correlation between the creep deformation amount and the like). Further, the calculation database 150 stores data representing the correlation between the amount of strain reaching the accelerated creep region in the test material and the creep test stress as shown in FIG.

  Each component described above is connected by a system bus 170.

  Next, various functional means stored in the program database 120 will be described.

  The program database 120 includes, as functional means, a crystal orientation distribution measuring means 121, a crystal orientation distribution quantifying means 122, a master curve deriving means 123, a creep strain amount estimating means 124, an accelerated creep region reaching strain amount estimating means 125, and a determining means. 126 is stored.

  The crystal orientation distribution measuring means 121 measures the crystal orientation distribution of the test material and the investigation material, and includes an OIM system using the EBSP method. And based on the crystal orientation information of the whole observation surface acquired by SEM, crystal orientation distribution is measured about the specific crystal orientation <uvw> seen from the stress axis direction.

The crystal orientation distribution quantifying means 122 quantifies the crystal orientation distribution measured by the crystal orientation distribution measuring means 121 using, for example, crystal orientation distribution parameters P _{<uvw>, 15} .

The master curve deriving unit 123 derives a master curve based on the crystal orientation distribution parameter P _{<uvw>, 15} quantified by the crystal orientation distribution quantifying unit 122, and the crystal orientation distribution parameter P _{<uvw> derives} a master curve indicating the correlation between the ₁₅ and the creep deformation amount. The master curve derived by the master curve deriving means 123 is stored in the calculation database 150.

The creep strain amount estimation means 124 _derives the crystal orientation distribution parameter P _{<uvw>, 15} of the investigation material quantified by the crystal orientation distribution quantification means 122 by the master curve derivation means 123 and stores it in the calculation database 150. By applying to the master curve, the creep strain amount of the investigation material is estimated.

  The acceleration creep region reaching strain amount estimation means 125 applies the stress received by the investigation material to data representing the correlation between the strain amount reaching the acceleration creep region and the creep test stress in the test material stored in the calculation database 150. Estimate the amount of strain that reaches the accelerated creep region of the investigation material.

  The determination unit 126 compares the creep strain amount of the investigation material estimated by the creep strain amount estimation unit 124 with the accelerated creep region arrival strain amount estimated by the acceleration creep region arrival strain amount estimation unit 125. If the creep strain amount of the investigation material is equal to or greater than the amount of strain that reaches the accelerated creep region, it is determined that continuous use of the target part including the investigation material is impossible, and the creep strain amount of the investigation material is less than the amount of strain that reaches the accelerated creep region In the case of, it is determined that the target part including the investigation material can be used continuously.

  Note that the various functional means in the creep damage evaluation apparatus 100 described above may be realized as a program stored in a storage device such as an appropriate program database 120 such as a memory or HDD (Hard Disk Drive), as described above. It may be realized as hardware. When implemented as a program, the control means 130 of the remaining life evaluation apparatus 100 reads the corresponding program from the program database 120 into the memory of the control means 130 in accordance with the program execution, and executes it.

  In the above embodiment, the case of a material having a face-centered cubic structure has been described. However, not only the face-centered cubic structure but also a body-centered cubic structure or a hexagonal close-packed structure is similarly created and focused. The present invention can be similarly applied by appropriately selecting the power crystal orientation.

  DESCRIPTION OF SYMBOLS 100 ... Creep damage evaluation apparatus, 120 ... Program database, 130 ... Control means, 140 ... Input / output interface, 150 ... Calculation database, 160 ... Display means, 170 ... System bus.

Claims (11)

A creep damage evaluation method for a metal material for evaluating the degree of damage of a metal material that has undergone creep damage,
Using a test material, obtaining a correlation between the amount of creep strain and the crystal orientation distribution in advance,
A process of measuring the crystal orientation distribution of the investigation material for creep damage evaluation;
Applying the measured crystal orientation distribution of the investigation material to the correlation between the creep strain amount and the crystal orientation distribution to estimate the creep strain amount of the investigation material;
Using the test material, the step of obtaining a correlation between the amount of strain reaching the accelerated creep region and the creep test stress in advance,
Estimating the amount of strain that the investigation material reaches the acceleration creep region from the correlation between the amount of strain reaching the acceleration creep region and the creep test stress, and the stress that the investigation material receives;
Comparing the estimated creep strain amount of the investigation material with the estimated strain amount of the investigation material reaching the accelerated creep region, and evaluating the damage degree of the investigation material. Of creep damage evaluation of metallic materials.   2. The creep damage evaluation method for a metal material according to claim 1, wherein an EBSP (Electron Back-Scatter Diffraction Pattern) method is used as the means for measuring the crystal orientation distribution.   2. The method for evaluating creep damage of a metal material according to claim 1, wherein an X-ray diffraction method is used as means for measuring the crystal orientation distribution.   The condition of the creep test performed in the step of obtaining the correlation between the creep strain amount and the crystal orientation distribution in advance using the test material is different from the condition to which the investigation material was exposed. The creep damage evaluation method for a metal material according to any one of the preceding claims.   5. The creep damage evaluation method for a metal material according to claim 4, wherein the creep test is performed under the same temperature and high stress as compared with the condition in which the investigation material was exposed.   5. The creep damage evaluation method for a metal material according to claim 4, wherein the creep test conditions are higher in temperature and stress than the condition in which the investigation material was exposed.   7. The method for evaluating creep damage of a metal material according to claim 5, wherein the stress condition of the creep test is in a range in which instantaneous plastic strain does not occur immediately after loading.   The method for evaluating creep damage of a metal material according to claim 6, wherein the temperature condition of the creep test is in a range in which the rate-determining process does not change from the rate-determining process of creep deformation under the condition where the investigation part is exposed.   In the step of evaluating the damage degree of the investigation material, when the estimated creep strain amount of the investigation material is equal to or larger than the estimated amount of strain that the investigation material reaches the accelerated creep region, the component including the investigation material The creep damage evaluation method for a metal material according to any one of claims 1 to 8, wherein the continuous use of the metal material is evaluated as being impossible.   The method for evaluating creep damage of a metal material according to any one of claims 1 to 9, wherein a GAM (Grain Average Misorientation) value is used instead of the crystal orientation distribution. A creep damage evaluation apparatus for a metal material that evaluates the degree of damage of a metal material that has undergone creep damage,
The first data representing the correlation between the amount of creep strain in the test material and the quantified crystal orientation distribution is accommodated, and the correlation between the amount of strain reaching the accelerated creep region in the test material and the creep test stress is represented. A database containing second data;
Crystal orientation distribution measuring means for measuring the crystal orientation distribution of the investigation material;
Crystal orientation distribution quantifying means for quantifying the crystal orientation distribution of the investigation material measured by the crystal orientation distribution measuring means;
A creep strain amount estimating means for applying a quantified crystal orientation distribution of the survey material to the first data to estimate a creep strain amount of the survey material;
An accelerated creep region reaching strain amount estimating means for estimating an accelerated creep region reaching strain amount at which the investigation material reaches the accelerated creep region from the second data and the stress received by the investigation material;
A judgment means for evaluating the degree of damage of the investigation material by comparing the estimated creep strain amount of the investigation material and the estimated amount of strain reaching the accelerated creep region. Creep damage evaluation device.

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