JP2002168853A - Method for evaluating life of metal material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating the life of a metal material capable of predicting the remaining life of even a metal material in which a damage that a plurality of microscopic cracks repeatedly occur and join together inside has occurred. SOLUTION: The surface structure of a high-temperature pipe of a metal material is inspected by a replica method, etc. On the basis of the results of the structure inspection, life consumption in the surface of the high-temperature pipe is obtained. Then a simulation on the development of a microscopic damage is performed. On the basis of the life consumption, the degree of development of the microscopic damage in the high-temperature pipe is computed. On the basis of the computation, the remaining life of the high-temperature pipe is estimated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the life of a metal material, and more particularly, to a welded portion of low alloy steel used as various pipes using a high temperature pressure resistant metal member such as a thermal power plant or a nuclear power plant. The present invention relates to a method for evaluating the life of a metal material, which is suitable for use in diagnosing the life of the metal material by evaluating the degree of progress of microscopic damage such as brittle creep damage occurring in the steel (coalescing and coalescence of grain boundary cracks). Things.

[0002]

2. Description of the Related Art In recent years, in a thermal power plant, as the operation time becomes longer, maintenance taking into account deterioration of equipment due to long-term use, thermal fatigue due to frequent start / stop, rapid load change, and the like is sufficiently considered. Management is becoming increasingly important. For example, in a large-diameter thick-walled pipe using a high-temperature pressure-resistant metal member, a crack such as a crack often occurs inside the welded portion, but the scratch cannot be detected only by inspection of the outer surface. Therefore, early detection of the flaw and development of an accurate measurement method of its size and density of the flaw are required. Therefore, as a method for obtaining a crack height, an edge echo method using an ultrasonic flaw detection method has been used.

However, in this end echo method, it is necessary to read the end echo from a subtle change in the waveform accompanying the scanning of the probe, so that it depends on the skill of the inspector in many cases. Has a problem that individual differences tend to appear, and the TOFD method (Ti
me of Flight Diffraction Technique) has been used as a technique for detecting and quantifying internal defects such as cracks.

FIG. 9 is an explanatory diagram for explaining the measurement principle of the TOFD method, in which a transmission probe 1 for transmitting ultrasonic waves,
The receiving probe 2 for receiving the ultrasonic wave is placed on the surface of the metal material 3 at an equal distance with a crack (defect) 4 generated inside the metal material 3 interposed therebetween. An ultrasonic wave 5 is transmitted into the metal material 3, the diffracted waves 6 from the upper end and the lower end of the crack 4 are detected by the receiving probe 2, the propagation time is measured, and the height of the crack 4 is calculated by the equation (1). Is determined by:
In the drawing, 7 is a surface wave, and 8 is a bottom surface reflected wave.

L = Zb−Zt = √ (tb ² · V ² / 4−S ² ) −√ (tt ² · V ² / 4−S ² ) (1) where L: crack height Zb: Depth of crack tip Zt: Depth of crack bottom D: Distance between transmitting probe 1 and receiving probe 2 S: D / 2 V: Velocity of diffracted wave tt: Propagation of diffracted wave from crack tip Time tb: Diffraction wave propagation time from crack bottom

[0006] In the TOFD method, since a flaw is detected by using a diffracted wave from a defect, the TOFD method is less susceptible to the inclination of the defect than the conventional ultrasonic flaw detection method, and there is a possibility of overlooking a directional defect. Although it has the advantage of decreasing the number of defects and improving the defect detection performance, it is difficult to predict the remaining life of the low alloy steel pipe. The reason is, for example, when evaluating a low alloy steel pipe used for 10 to 20 years, whether the detected defect is due to creep damage caused by aging of the metal material, or whether the detected defect is already in the metal material at the time of manufacture. This is because it cannot be determined whether or not the error has occurred.

Accordingly, a method for evaluating the damage of a metal material capable of predicting the remaining life of the metal material has been proposed (Japanese Patent Application No. 11-338672). This method determines whether the scratch inside the metallic material is due to creep damage or not, and determines whether the scratch is due to creep damage caused by aging after manufacturing or caused during manufacturing. Is a method of determining whether
Based on the distribution state of the diffracted waves from the scratch inside the metal material and the damage state of the surface, it is determined whether the scratch is a damage due to creep damage, and the remaining life of the metal material is predicted with high accuracy.

[0008]

In the above-described method for evaluating damage to a metal material, the method for diagnosing the remaining life of a metal material includes a method based on a life consumption rate by a replica collected from the surface of the metal material, A method based on creep crack propagation analysis based on fracture mechanics based on internal flaws detected by the TOFD method is also used, and the shorter of the lives estimated by both methods is replaced by The remaining life is assumed.

However, the above method, especially the latter method, is based on the premise that a single crack grows and propagates. For example, a plurality of microscopic cracks grow while repeating generation and coalescence. In cases such as damage, the remaining life diagnosis by the above method may not correspond to the actual damage state, and as a result, the remaining life diagnosis may be inaccurate. There was a problem. In fact, looking at the damage condition of the welded portion of the pipe described above, it can be seen that a plurality of microscopic cracks are growing while repeating occurrence and coalescence, and the above evaluation method does not correspond to this damaged state of the pipe there is a possibility.

[0010] The present invention has been made in view of the above-mentioned circumstances, and the present invention has been developed in consideration of the above-mentioned problems. It is an object of the present invention to provide a method for evaluating the life of a metal material, which can predict the life of a metal material.

[0011]

In order to solve the above-mentioned problems, the present invention employs the following metal material life evaluation method. That is, in the method for evaluating the life of a metal material according to claim 1, the structure of the surface of the metal material is inspected, and the life consumption on the surface of the metal material is determined based on the result of the structure inspection. And calculating the degree of development of microscopic damage inside the metal material based on the calculation result, and estimating the lifetime of the entire metal material based on the calculation result.

In this method, the structure of the surface of the metal material is inspected using a replica method or the like, and the presence or absence of damage due to creep and the deterioration of the metal structure on the surface are determined.
The life consumption on the surface of this metal material is determined. Then
Based on the life consumption, a simulation of microscopic damage propagation inside the thickness is performed. This simulation is a method of calculating the degree of progress of microscopic damage of a metal material (that is, the occurrence and coalescence of grain boundary cracks). As a result of this simulation, the damage distribution in the thickness direction of the metal material is estimated every moment. The Rukoto. This makes it possible to predict the remaining life of the entire metal material in consideration of the state of damage inside the metal material.

According to a second aspect of the present invention, there is provided the metal material life evaluation method according to the first aspect.
The method is characterized in that a sample is collected from the surface of the metal material and subjected to chemical analysis, the amount of impurities in the sample is quantified, and the rate of progress of microscopic damage of the metal material is estimated based on the amount of impurities.

In this method, a sample is collected from the surface of a metal material and subjected to chemical analysis to determine the amount of impurities in the sample. Since the void number density, which is one of the factors indicating the amount of damage in a metal material, increases with time, and the amount of this increase increases as the content of impurities increases,
When the impurities in the metal material are quantified, the increase in the void number density in the metal material can be determined from the content of the impurities.
Since the increase amount of the void number density is closely related to the damage propagation speed, it is possible to estimate the damage propagation speed from the increase amount of the void number density.

According to a third aspect of the present invention, in the method for evaluating the life of a metal material according to the first or second aspect, the calculation of the degree of progress is performed based on a material characteristic, a stress load characteristic and a current load characteristic of the metal material. A grain boundary model is created based on each data of the damage in the above, and a fracture progress process of each grain boundary when stress is applied to the grain boundary model is calculated based on the life consumption of the surface. .

In this method, first, a grain boundary model is created based on the data on the material characteristics, stress load characteristics, and initial damage of the metal material. The fracture progress characteristic is calculated based on the life consumption obtained separately. This makes it possible to more accurately predict the remaining life of the entire metal material in consideration of the damage progression state inside the metal material.

According to a fourth aspect of the present invention, in the method for evaluating the life of a metal material according to the first, second, or third aspect, the calculation of the degree of progression of the damage distribution inside the thickness is performed by using the metal material. Calculating the degree of development of microscopic damage at the time of stress loading of the metal material at a plurality of locations inside the metal material by applying external stress to the metal material, and estimating the progress of damage development throughout the metal material. It is characterized by.

In this method, by applying a stress to the metal material from the outside, the degree of development of microscopic damage inside the metal material when the stress is applied to the metal material is calculated. By performing this calculation at a plurality of locations in the thickness direction in the metal material, it is possible to know the progress of damage in the entire metal material.

According to a fifth aspect of the present invention, there is provided the metal material life evaluation method according to the fourth aspect.
It is characterized in that a progress of damage inside the metal material is estimated based on a damage distribution and / or a stress distribution in the metal material.

According to this method, the damage progression inside the metal material is estimated based on the damage distribution and / or the stress distribution in the metal material, so that the damage at each part corresponding to the damage distribution and / or the stress distribution is estimated. Can be estimated, and as a result, the rupture life of each part can be estimated.

According to a sixth aspect of the present invention, in the method for evaluating the life of a metal material according to any one of the first to fifth aspects, a transmission probe for transmitting an ultrasonic wave to a surface of the metal material is provided. A probe and a receiving probe that receives ultrasonic waves are placed with the damaged portion in the metal material interposed therebetween, and ultrasonic waves are transmitted into the metal material by the transmission probe, and the probe from the damaged portion is transmitted. Diffraction waves are detected by the reception probe, damage distribution in the metal material is detected, and a degree of microscopic damage progression of the metal material is calculated based on the detection result.

In this method, ultrasonic waves are transmitted into the metal material by the transmission probe, and diffraction waves from a damaged portion inside the metal material are detected by the reception probe, whereby the inside of the metal material is detected. The micro-scratches that occur are detected, and the size and density of the scars are quantified. As a result, the life of the metal material can be easily and accurately estimated based on the quantified minute flaws inside the metal material and the separately obtained life consumption distribution inside the thickness. It is possible to easily and accurately predict the remaining life of the metal material regardless of the damage state of the metal material.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the method for evaluating the life of a metal material according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a welded portion of a high-temperature pipe, which is an example of a metal material to which the life evaluation method of one embodiment of the present invention is applied,
In the drawing, reference numeral 11 denotes a high-temperature pipe made of a low-alloy steel pipe or the like. Low-alloy steel sheets 12 and 16 are bent into a cylindrical shape, and end faces 12 a and 12 b along the longitudinal direction thereof are joined to each other by a weld metal 13. I have. A flaw 14 to be detected is generated in the weld metal 13. Reference numeral 15 denotes a replica of the surface of the metal material.

The composition of the weld metal 13 is, for example, 2.2.
Impurities composed of 5% Cr-1% Mo-0.12% C-balance Fe and which are greatly related to the rate of creep damage development of the weld metal 13 are, for example, P (phosphorus), As (arsenic), Sn ( Tin) and Sb (antimony). The degree of creep damage (lifetime consumption rate) of the weld metal 13 is shown in FIG.
As shown in (b), it is larger than the surrounding steel plates 12 and 16, which substantially matches the concentration of the impurity Sb obtained by the impurity analysis (chemical analysis) of each part.

Next, the life evaluation method of the metal material of the present embodiment will be described with reference to the high temperature pipe 11 shown in FIG.
Explanation will be made based on FIG. 1. Estimation of Life Consumption by Replica Method (1) Collection of Replica A replica 15 of the surface of the high-temperature pipe 11 is collected by a method of transferring the surface of the high-temperature pipe 11 to a plastic film. For example, rough polishing and fine polishing are sequentially performed on the surface, the surface is finished to a mirror surface, the inspection target portion of the mirror surface is selectively removed by etching, a replica plastic film is pressed on the etched portion, and the etching is performed. The surface irregularities are transferred to a plastic film.

(2) Observation of Replica and Estimation of Life Consumption The replica 15 is observed using an optical microscope, and the presence or absence of voids (creep voids) due to creep damage and the distribution state thereof are examined. Here, it is roughly determined whether or not the scratch 14 is due to creep damage. Next, the presence or absence of creep voids and the distribution thereof are precisely observed using a scanning electron microscope (SEM). For example, the number of generated creep voids is measured, the creep void number density is determined based on the measured value, and the life evaluation diagram (creep void number density and creep damage degree (life consumption)) determined in advance in FIG. Is estimated from the graph showing the relationship (1).

2. Estimation of the change in the rate of progress of microscopic damage by chemical component analysis (1) Quantification of impurity content The oxide film on the surface of the sampled area of the weld metal 13 is removed by grinding until a metallic luster is obtained. Then, the exposed metal portion is further ground to collect chips. Next, P, As, Sn, and Sb are analyzed using the chips, and the content of impurities is quantified. The analysis method of each element is as follows. P: Atomic absorption method (Japanese Industrial Standard; JIS G125)
7) As, Sn, Sb: hydride generation ICP emission spectrometry

(2) Estimation of the change in the rate of development of microscopic damage A graph showing the relationship between the void number density and the elapsed time as shown in FIG. Based on the impurity content determined as described above, the amount of change in the void number density is determined from the graph. Since there is a close relationship between the amount of change in the void number density and the amount of change in the speed of the microscopic damage, if the amount of change in the void number density is determined, the change in the speed of the microscopic damage can be obtained. The quantity can be easily estimated. Next, the creep embrittlement coefficient (CEF) is determined from the impurity analysis results based on the following equation (2). This value is used as a parameter representing the impurity content. CEF = P (wt.%) + 2.4As (wt.%) + 3.6Sn (wt.%) + 8.2Sb (wt.%) (2)

3. Detection of Damage Distribution by TOFD Method (1) Ultrasonic Flaw Detection by TOFD Method Ultrasonic flaw detection of the high-temperature pipe 11 is performed by using a metal material damage evaluation apparatus to which the TOFD method is applied.

FIG. 5 is a block diagram showing an apparatus for evaluating the damage of a metal material. In the figure, reference numeral 21 denotes a transmitter for transmitting the transmission probe 1 by ultrasonic waves, and reference numeral 22 denotes a sample taken from the surface of the metal material 3. A creep characteristic estimating unit for estimating the creep characteristic of the metal material 3 based on the result of the chemical analysis of the sample, 23
Is a detecting unit that receives a diffracted wave 24 from a flaw in the metal material 3 detected by the receiving probe 2 and detects a damage distribution of the metal material based on the distribution state of the diffracted wave 24; The control section controls the operation of the probe 1, the receiving probe 2, the transmitter 21, the creep characteristic estimation section 22, and the detection section 23.

In order to perform ultrasonic flaw detection of the high-temperature pipe 11 using the damage evaluation apparatus, the transmission probe 1 and the reception probe 2 are connected to the welding metal 13 along the circumferential direction of the surface of the high-temperature pipe 11. At the sandwiching position, the high-temperature pipe 11 is placed at an equal distance with a scratch 14 generated inside the high-temperature pipe 11 interposed therebetween.
1 transmits an ultrasonic wave 5 and the receiving probe 2
The presence or absence of the flaw 14 in the high temperature pipe 11 is detected by detecting the diffracted wave 24 from. Here, if both the transmission probe 1 and the reception probe 2 are scanned along the welding line, a flaw 1
4 distributions can be detected.

4. Implementation of Microscopic Damage Propagation Simulation A microscopic damage propagation simulation is performed based on the flowchart shown in FIG. (1) Data input The material characteristics, load characteristics, initial damage, and other data of the high-temperature piping 11 are input. These data are modified as follows. a. Correction of Material Characteristics and Load Characteristics In order to consider the influence of impurities on the material characteristics and load characteristics, the material characteristics and load characteristics of the high-temperature pipe 11 are corrected based on the results of quantification of the content of impurities by chemical composition analysis.

The relationship between the surface damage of the high-temperature pipe 11 and the stress distribution is previously stored in a database.
The stress distribution inside the high-temperature pipe 11 is estimated. Also, TOF
The stress distribution is estimated from the result of the internal damage inspection of the high temperature pipe 11 by the D method. Next, based on these stress distributions, a plurality of models having different material characteristics and load characteristics are created inside the wall thickness, and the material characteristics and / or load characteristics of the high-temperature pipe 11 are corrected based on these models. When creating these models, changes in damage distribution and stress distribution due to the coupling of a plurality of models are considered.

B. Correction of Initial Damage The relation between the surface damage of the high-temperature pipe 11 and the distribution of damage in the thickness direction is previously stored in a database.
1. Estimate the initial damage distribution inside. Further, the initial damage distribution is estimated from the result of the internal damage inspection of the high temperature pipe 11 by the TOFD method. Next, a plurality of models having different initial damages are created based on these initial damage distributions, and the initial damages of the high-temperature pipe 11 are corrected based on these models. When creating these models, changes in damage distribution and stress distribution due to the coupling of a plurality of models are considered.

(2) Microscopic damage propagation simulation Based on FIGS. 6 and 7, a microscopic damage propagation simulation is performed.
carry out. a. Creation of a grain boundary model Based on various data input,
Create a grain boundary model. In this analysis model,
Probability distribution suitable for the boundary length L and the fracture resistance value R of the grain boundary;
Representative values are assumed based on the input data, and the grain boundary
Create a file. For example, if a normal distribution is assumed for L and R,
The average value of L^m, Standard deviation L^s, R average R ^m,standard
Deviation R^sIs assumed.

B. Creating Stress Model and Load Model on High Temperature Pipe 11 A stress is applied to the high temperature pipe 11 and a load model of the high temperature pipe 11 corresponding to the stress load is created. This hot pipe 1
In the case of 1, a crack is generated inside due to stress. At the grain boundary adjacent to the crack, assuming that the driving force for breaking the grain boundary is D, the damage progress rate (dR / dT) is equal to -D (d
R / dT = -D). Negative (R <0)
Then, the grain boundaries break and cracks occur. At the grain boundary adjacent to the crack, the grain boundary fracture driving force D is equal to the sum of the crack generation driving force F and the product of the crack propagation driving force K and the crack length C adjacent to the grain boundary (D = F + CK). In addition, at a grain boundary that is not adjacent to a crack, the breaking driving force D at the grain boundary is equal to the crack generation driving force F (D = F).

C. Investigation of Crack Length, etc. Based on the load model of the high-temperature pipe 11, the length and distribution of the micro-cracks inside the high-temperature pipe 11 generated by stress are investigated.

D. Judgment of Completion of Calculation In the model, the calculation ends when the cracked grain boundaries are united and the macroscopic crack is connected over the entire length of the model. Alternatively, the calculation may be terminated when a calculation end condition (for example, a critical grain boundary crack density, a critical crack length, or the like) given as an input value is reached.

If it is determined that the calculation has been completed, the calculation is terminated, and the remaining life in the high-temperature pipe 11 is estimated based on the calculation result. In addition, when it is determined that the calculation has not been completed, the stress load on the high-temperature pipe 11 and the crack length and the like are again checked, the calculation is determined to be completed, and it is determined that the calculation is completed. In this case, the calculation is terminated, and the remaining life of the high-temperature pipe 11 is estimated based on the calculation result. On the other hand, when it is determined that the calculation is not completed, the stress load to the high-temperature pipe 11 is calculated again. Repeat the end determination. As described above, the determination of the stress load on the high-temperature pipe 11 to the end of the calculation is repeatedly performed until it is determined that the calculation is completed. When it is determined that the calculation is completed, the calculation is completed. The remaining life of the entire high-temperature pipe 11 is estimated based on the result.

Here, a more specific example of the microscopic damage propagation simulation will be described with reference to FIG. Consider a case in which a stress having a stress distribution as shown in FIG. 8A is applied to the weld interface (HAZ) of the high temperature pipe 11.
Here, the magnitude of the stress is examined at, for example, three points in the thickness direction of the welded portion, and the stress is defined as stress σ _{1 to} σ ₃ . Next, a simulation is performed for each of the stresses σ _{1 to} σ ₃ based on the material characteristics of the welded portion of the high-temperature pipe 11, and a load corresponding to each of the stresses σ _{1 to} σ ₃ as shown in FIG. Create a model.

Next, based on these three load models,
Damage Dc ₁ to DC ₃ corresponding to the respective stress σ ₁ ~σ ₃ calculates, calculated every moment the thickness direction of the damage distribution as shown in Figure 8 (c). Thereby, the life until the fracture of the entire welded joint as shown in FIG. 8D is estimated.

As described above, according to the metal material life evaluation method of the present embodiment, the life consumption of the high-temperature pipe 11 is estimated by the replica method, and the rate of development of microscopic damage by chemical composition analysis. And the damage distribution is detected by the TOFD method, and the microscopic damage propagation simulation is performed using these results. Even in the case where a large crack grows while repeating generation and coalescence, the remaining life of the high-temperature pipe 11 can be easily and accurately predicted.

The embodiments of the metal material damage evaluation method and apparatus of the present invention have been described above with reference to the drawings. However, the specific structure is not limited to the above embodiments, and the gist of the present invention is as follows. The design can be changed without departing from the range.

[0044]

As described above, according to the method for evaluating the life of a metal material according to the first aspect of the present invention, the life consumption on the surface of the metal material is determined based on the result of the microstructure inspection on the surface of the metal material. Then, the degree of progress of the microscopic damage of the metal material is calculated based on the life consumption, so that it is possible to easily and accurately predict the remaining life of the metal material regardless of the state of damage inside the metal material. it can.

According to the method for evaluating the life of a metal material according to the second aspect, a sample is collected from the surface of the metal material and subjected to chemical analysis to quantify the amount of impurities in the sample. Since the amount of change in the rate of progress of the microscopic damage of the metal material is estimated based on this, the remaining life of the metal material can be more accurately predicted.

According to the method for evaluating the life of a metal material according to the third aspect, a grain boundary model is created on the basis of the data on the material characteristics, stress load characteristics, and initial damage of the metal material, and based on the life consumption. Calculates the fracture characteristics of each grain boundary when a stress load is applied to the grain boundary model, making it easy to calculate the degree of microscopic damage of the metal material and more accurately predicting the remaining life of the metal material can do.

According to the method for evaluating the life of a metal material according to the fourth aspect of the present invention, a stress is applied to the metal material from the outside to determine the degree of microscopic damage progression when the metal material is subjected to a stress. Since the calculation is performed at a plurality of locations inside and the progress of the damage inside the metal material is estimated, the progress of the damage inside the metal material can be known.

According to the method for evaluating the life of a metal material according to the fifth aspect, the progress of damage inside the metal material is estimated based on the damage distribution and / or the stress distribution in the metal material. Can be estimated, and the ultimate rupture life of the metal material can be estimated.

According to the method for evaluating the life of a metal material according to the sixth aspect, an ultrasonic wave is transmitted into the metal material by the transmission probe and a diffraction wave from the damaged portion is detected by the reception probe.
Since the damage distribution in the metal material is detected and the degree of microscopic damage of the metal material is calculated based on the detection result, the life of the metal material can be easily and accurately estimated.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a welded portion of a high-temperature pipe to which a life evaluation method according to an embodiment of the present invention is applied.

FIG. 2 is a flowchart showing a life evaluation method according to an embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the creep void number density and the degree of creep damage (lifetime consumption).

FIG. 4 is a diagram showing a relationship between void number density and elapsed time when the content of impurities is used as a parameter.

FIG. 5 is a block diagram showing a metal damage evaluation apparatus according to an embodiment of the present invention.

FIG. 6 is a flowchart showing a microscopic damage propagation simulation according to one embodiment of the present invention.

FIG. 7 is a schematic diagram showing a grain boundary fracture resistance distribution model for microscopic damage propagation simulation according to one embodiment of the present invention.

FIG. 8 is a schematic diagram showing a specific example of a microscopic damage propagation simulation according to one embodiment of the present invention.

FIG. 9 is an explanatory diagram for explaining the measurement principle of the TOFD method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission probe 2 Receiving probe 3 Metal material 4 Crack (defect) 5 Ultrasonic wave 6 Diffracted wave 7 Surface wave 8 Bottom reflected wave 11 High-temperature piping 12 Low alloy steel plate 12a, 12b End face 13 Weld metal 14 Scratches 15 Replica 21 Transmitter 22 Creep characteristic estimating unit 23 Detecting unit 24 Diffracted wave 25 Control unit

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshihide Inokari 5-7-17-1 Fukahori-cho, Nagasaki-shi, Nagasaki Sanishi Heavy Industries Co., Ltd. Nagasaki Research Institute (72) Inventor Nobuhiko Nishimura 5-717, Fukahori-cho, Nagasaki-shi, Nagasaki No. 1 Inside the Nagasaki Research Laboratory of Mitsubishi Heavy Industries, Ltd. (72) Inventor Masaaki Fujita 1-1, Akunouramachi, Nagasaki City, Nagasaki Prefecture F-term in the Nagasaki Shipyard, Mitsubishi Heavy Industries, Ltd.

Claims (6)

[Claims] 1. A structure inspection of a surface of a metal material is performed, a life consumption amount on a surface of the metal material is obtained based on a result of the structure inspection, and a microscopic damage inside the metal material is determined based on the life consumption amount. Calculating the degree of progress of the metal material, and estimating the life of the entire metal material based on the calculation result. 2. A method according to claim 1, wherein a sample is collected from the surface of said metal material and subjected to chemical analysis to quantify the amount of impurities in said sample, and to estimate a rate of development of microscopic damage of said metal material based on said amount of impurities. The method for evaluating the life of a metal material according to claim 1, wherein: 3. The calculation of the degree of progress is performed by creating a grain boundary model based on data of material properties, stress load properties, and damage at the present time of the metal material, and calculating the grain boundary based on the life consumption of the surface. 3. The method according to claim 1, wherein a fracture progress process of each grain boundary when a stress is applied to the boundary model is calculated. 4. The method according to claim 1, wherein the step of calculating the degree of progress of the damage distribution inside the thickness includes applying an external stress to the metal material to determine the degree of microscopic damage during stress loading of the metal material. The method for evaluating the life of a metal material according to claim 1, wherein the calculation is performed at a plurality of locations, and the progress of the damage inside the metal material is estimated. 5. The method for evaluating the life of a metal material according to claim 4, wherein the progress of the damage inside the metal material is estimated based on the damage distribution and / or the stress distribution in the metal material. 6. A transmitting probe for transmitting an ultrasonic wave and a receiving probe for receiving an ultrasonic wave are placed on a surface of the metal material with a damaged portion in the metal material interposed therebetween. An ultrasonic wave is transmitted into the metal material by a probe, a diffraction wave from the damaged portion is detected by the reception probe, and a damage distribution in the metal material is detected. Based on the detection result, the metal material is detected. The method for evaluating the life of a metal material according to any one of claims 1 to 5, wherein a degree of progress of the microscopic damage is calculated.