JP2013019758A - Damage evaluation method and device for metal member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve early detection of creep damage of a metal member formed of high Cr steel to ensure a time required for maintenance management.SOLUTION: A plurality of measurement projections 10 are formed across a weld zone W on the external surface of a steam piping P of a thermal power plant boiler. A creep damage evaluation device 12 comprises: a storage part 16 for storing a correlation map 14 which is created based on past measured values and indicates a correlation relation between strain of a welding heat affected zone HAZ and a lifetime consumption rate; a creep strain measurement part 18 to which a measured value of an interval 2L between the measurement projections 10 and which calculates creep strain of the external surface of the steam piping P; a first estimation part 20 which calculates creep strain of internal and external surfaces and the board thickness inside of the welding heat affected zone HAZ from the creep strain between the intervals 2L by using a finite element method (FEM); and a second estimation part 22 which estimates lifetime consumption rates of the internal and external surfaces and the board thickness inside of the welding heat affected zone HAZ from the creep strain and the correlation map 14.

Description

  The present invention is, for example, a creep damage evaluation method and an evaluation apparatus suitable for evaluating creep damage occurring in, for example, a welded portion of a steam pipe of a boiler for a thermal power plant and estimating the remaining life until creep rupture. About.

  Ferritic high Cr heat resistant steel that has excellent high temperature characteristics and can be used for a long time under high temperature and high pressure is used for steam piping of boilers for thermal power plants. In piping used under such high temperature and pressure, breakage due to creep phenomenon becomes a problem. Therefore, maintenance management for creep rupture is required. The progress rate of creep damage increases particularly in the weld heat affected zone of the welded part. Creep rupture is that creep voids (holes) generated in the weld heat affected zone etc. repeat growth and coalescence, grow into microcracks, and then macrocracks progress to penetrate the pipe wall thickness, It leads to breakage.

  FIG. 12 shows a crack c generated at a weld W of a steam pipe of a boiler made of 2Cr steel. As shown in FIG. 12, a crack c is generated in the weld heat affected zone HAZ formed between the weld metal w and the base material m of the steam pipe, and the fracture is reached. In addition, the number of creep voids is increased inside the surface of the steam pipe and tends to be the starting point of the crack c.

  As a method for detecting the presence or absence of creep voids on the surface of a metal member, there is a replica method. In the replica method, the surface to be inspected is polished to a mirror surface, the mirror surface is selectively removed by etching, a plastic film for replica is pressed onto the etched surface, and the unevenness of the etched surface is transferred to the plastic film. Next, the presence or absence of creep voids and their distribution are observed using a scanning electron microscope.

  There is also a method for determining the influence of the creep damage progress rate from component analysis of a metal member. In this method, after removing the oxide film on the surface of the metal member, the exposed metal member is ground to collect chips. Component analysis is performed using this chip, the creep embrittlement index (CEF) is determined from the amount of impurities, and the correlation between the creep embrittlement index and the progress rate of creep damage is reflected in future maintenance management procedures. .

  There is a nondestructive inspection method using ultrasonic waves as a method for detecting scratches inside the metal member. This method detects a defect by transmitting an ultrasonic wave inside a metal member and detecting a reflected wave reflected by the defect. As a method using ultrasonic waves, a plurality of ultrasonic waves are transmitted from a plurality of vibration elements so as to form a single wavefront running in an intended direction, and a reflected wave reflected by the defect is detected, thereby detecting the position of the defect. There is a phased array method with high measurement accuracy. In addition, a time difference between a reflected wave reflected from the surface of the metal member and a reflected wave reflected from the defect is provided with a vibration element that transmits ultrasonic waves to the surface of the metal member and a receiving element that reflects the reflected wave from the scratch inside the metal member Therefore, there is a method such as a TOFD method that can accurately detect the “depth” of the defect.

  In Patent Document 1, since the ultrasonic flaw detection method cannot determine whether the scratch inside the metal member is caused by creep damage caused by secular change or has already occurred at the time of manufacture, the remaining life of the metal member is predicted. Means for solving the problem of being impossible is disclosed. This means determines whether or not the damage is caused by creep damage by using an ultrasonic flaw detection method in combination with a replica method or a component analysis method for observing the distribution of creep voids on the surface of a metal member.

  Patent Document 2 discloses a creep damage evaluation method that can evaluate the creep damage of the bend portion of the boiler pipe and accurately and simply predict the remaining life of the bend portion. This method measures the amount of deformation of the bend before and after boiler operation, calculates the bending moment acting on the bend after operation from the difference in the amount of deformation, and correlates the bending moment of the bend and the creep damage that has been obtained in advance. From the relationship, the creep damage of the bend portion is predicted.

JP 2001-153865 A JP 2003-232719 A

  Among high Cr steels applied to boiler steam piping, 9-12Cr steel has a higher creep rupture strength than 2Cr steel. However, compared with 2Cr steel, 9-12Cr steel has less structural change when subjected to creep damage. If it is not at the end of its life, crack extension is not observed inside the metal member, and creep voids are generated on the outer surface. Absent. For this reason, the ultrasonic evaluation method disclosed in Patent Document 1 cannot find the creep damage inside the metal member unless it reaches the end of its life. Even on the metal member surface, when the replica method or the component analysis method is used, the creep void cannot be detected unless the end of life is reached.

  For example, in terms of the creep life consumption rate when the time to creep rupture is 100%, in 2Cr steel, the creep life consumption rate is about 60%, and dense creep voids and microcracks can be detected. With 9-12Cr steel, dense creep voids and microcracks cannot be detected unless the creep life consumption rate is about 80%. For this reason, there is a problem that the time from detection of creep damage to creep rupture is short, sufficient time for maintenance management cannot be secured, and sufficient maintenance management cannot be performed.

  The evaluation method disclosed in Patent Document 2 can be applied only to a metal member that significantly receives a bending moment, and its application range is limited.

  In view of the problems of the prior art, the present invention realizes a creep damage evaluation method that enables early detection of creep damage and secures sufficient time for maintenance management even in high Cr steel such as 9-12Cr steel. With the goal.

  In order to achieve such an object, the damage evaluation method for a metal member according to the present invention prepares in advance a correlation map indicating the correlation between the creep strain of the metal member and the life consumption rate due to creep damage from the past measurement values. From the map creation step, the displacement generated on the surface of the metal member, the creep strain measurement step of calculating the creep strain generated on the surface of the metal member from the displacement, and the creep strain measured in the creep strain measurement step, From the first estimation step for estimating the creep strain inside the metal member by an analytical method, the creep strain on the surface of the metal member measured in the strain measurement step, and the creep strain inside the metal member estimated in the first estimation step, to a correlation map And a second estimation step for estimating a life consumption rate due to creep damage of the metal member.

  In the method of the present invention, the creep strain inside the metal member is estimated from the creep strain generated on the surface of the metal member by using an analytical method such as a finite element method (FEM). Based on the correlation map, the creep life consumption rate on the surface and inside of the metal member is estimated from the creep strain on the surface and inside of the metal member. Thus, since creep damage is estimated based on the creep distortion which generate | occur | produces in a metal member, even in 9-12Cr steel, a creep damage degree can be grasped | ascertained early. As a result, a sufficient time for maintenance management of the metal member can be secured, so that maintenance management becomes easy.

  In the method according to the present invention, the creep strain measurement step includes forming two or more measurement projections on the surface of the metal member in advance, and measuring the creep between the measurement projections from the distance between the measurement projections measured before and after the occurrence of creep strain. It is good to calculate distortion. Thus, it becomes easy to measure the creep strain on the surface of the metal member by providing the measurement projections in advance. The measurement protrusions may be arranged in a region where the creep damage progress rate is high and the degree of creep damage is particularly to be monitored.

  In the method of the present invention, when a tensile load is applied to the metal member, the creep strain measurement step measures the depth of the recess generated on the surface of the metal member, and the creep strain generated on the surface of the metal member. It is good to use as an index. When the metal member is subjected to a tensile load, a concave portion is generated on the surface of the metal member, particularly in a region where the progress rate of creep damage is large, such as a weld heat affected zone. Therefore, the depth of the concave portion is regarded as a displacement generated on the surface of the metal member, and the creep strain is calculated from this, whereby the creep life consumption rate in this region can be easily obtained.

  Further, a more accurate creep life consumption rate can be estimated by using the creep strain calculation method for forming the measurement protrusion and the creep strain calculation method for detecting the depth of the recess on the metal member surface.

  Furthermore, in addition to the creep damage evaluation method, a structure inspection of the surface of the metal member is performed, and based on the result of the structure inspection, the presence or absence of creep damage on the surface of the metal member is determined. The lifetime consumption rate of the metal member may be estimated comprehensively from the calculated lifetime consumption rate. Thereby, the creep life consumption rate of the metal member can be estimated more accurately.

  The metal member damage evaluation apparatus of the present invention that can be directly used for the implementation of the method of the present invention is created based on past measurement values, and shows the correlation between the creep strain of the metal member and the lifetime consumption rate due to creep damage. A correlation map, a storage means for storing the correlation map, a creep strain measuring means for inputting a displacement generated on the surface of the metal member and calculating a creep strain generated on the surface of the metal member from the displacement; and a creep strain measuring means The first estimation means for estimating the creep strain inside the metal member by an analytical method from the creep strain measured in step 1, the creep strain on the surface of the metal member measured by the creep strain measurement means, and the metal estimated by the first estimation means And second estimation means for estimating a life consumption rate due to creep damage of the metal member based on the correlation map from the creep strain inside the member.

  In the apparatus of the present invention, the creep strain generated on the surface of the metal member is calculated, and the creep strain inside the metal member is estimated from the creep strain using an analytical method such as a finite element method (FEM). Based on the correlation map, the creep life consumption rate on the surface and inside of the metal member is estimated from the creep strain on the surface and inside of the metal member. Thus, since creep damage is estimated based on the creep distortion which generate | occur | produces in a metal member, even in 9-12Cr steel, a creep damage degree can be grasped | ascertained early. This facilitates maintenance management of the metal member.

  In the apparatus of the present invention, two or more measurement protrusions formed in advance on the surface of the metal member are provided, and the distance between the measurement protrusions measured before and after the occurrence of the strain is input to the strain measurement means. It is preferable to calculate the creep strain between the measurement protrusions. Thus, it becomes easy to measure the creep strain on the surface of the metal member by forming the measurement protrusion on the surface of the metal member. The measurement protrusions may be arranged in a region where the creep damage progress rate is high and the degree of creep damage is particularly to be monitored.

  In the device of the present invention, the measurement protrusions may be arranged on both sides of the weld line of the metal member, and the life consumption rate due to creep damage of the heat affected zone of the weld line may be estimated. The progress rate of creep damage in the weld zone is the same for the base metal of the metal member and the weld metal, but the progress rate of creep damage in the weld heat affected zone is larger than these regions. Therefore, in particular, the creep rupture time of the metal member can be accurately estimated by estimating the creep life consumption rate of the weld heat affected zone.

  According to the method of the present invention, a map creation step for creating in advance a correlation map showing a correlation between a creep distortion of a metal member and a life consumption rate due to creep damage from a past measurement value is generated on the surface of the metal member. The creep strain inside the metal member is analyzed by an analytical method from the creep strain measurement step for calculating the creep strain generated on the surface of the metal member from the displacement and the creep strain measured in the creep strain measurement step. Lifetime consumption due to creep damage of metal member based on correlation map from first estimation step to be estimated, creep strain of metal member surface measured in creep strain measurement step and creep strain in metal member estimated in first estimation step A second estimation step for estimating the rate, and creep damage is estimated based on the creep strain generated in the metal member. Oite also, it can grasp the creep damage degree at an early stage. As a result, a sufficient time margin for maintenance management of the metal member can be obtained.

  According to the apparatus of the present invention, a correlation map that is created based on past measurement values and indicates a correlation between the creep strain of the metal member and the life consumption rate due to creep damage, a storage unit that stores the correlation map, and the metal member The creep strain measuring means for calculating the creep strain generated on the surface of the metal member from the displacement generated by the displacement generated on the surface of the metal member, and the creep strain measured by the creep strain measuring means from the inside of the metal member by an analytical method The first estimation means for estimating the creep strain of the metal member, the creep strain on the surface of the metal member measured by the creep strain measurement means, and the creep strain inside the metal member estimated by the first estimation means, based on the correlation map, Since it comprises the second estimating means for estimating the lifetime consumption rate due to creep damage, the same effect as the method of the present invention can be obtained.

It is a perspective view of the steam piping which concerns on 1st Embodiment of this invention and becomes lifetime prediction object. It is an enlarged view of the processus | protrusion for measurement formed in the said steam piping. It is sectional drawing of the welding part of the said steam piping. It is a block diagram of the creep damage evaluation apparatus which concerns on 1st Embodiment of this invention. In the first embodiment, (A) is a diagram showing the creep strain of the weld heat affected zone, and (B) is a diagram for predicting the life consumption rate from the creep strain of the weld heat affected zone. It is a diagram which shows the creep distortion of the welding heat affected zone estimated from the creep distortion between projections for measurement in the first embodiment. It is a diagram which shows the lifetime consumption rate actually estimated from the creep distortion of the welding heat affected zone in 1st Embodiment. In 1st Embodiment, it is the diagram which estimated the lifetime consumption rate of steam piping comprehensively using this invention and the other method together. It is sectional drawing of the steam piping which concerns on 2nd Embodiment of this invention. In relation to the second embodiment, (A) is a diagram showing the creep strain of the weld heat affected zone, and (B) is a diagram for predicting the life consumption rate from the creep strain of the weld heat affected zone. It is a diagram which shows the lifetime consumption rate estimated from the hollow amount of the welding heat affected zone actually estimated in 2nd Embodiment. It is a diagram which shows the crack which generate | occur | produced in the welding part of steam piping, and the creep void surface density which generate | occur | produced in steam piping.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

(Embodiment 1)
1st Embodiment which applied this invention to the steam piping which consists of 9-12Cr steel of the boiler for thermal power plants is described based on FIGS. FIG. 1 shows a steam pipe P that evaluates creep damage and predicts its remaining life. The steam pipe P is, for example, a large-diameter pipe having a diameter of 400 to 700 mm that is disposed between the boiler and the steam turbine and supplies the high-pressure steam S from the boiler to the steam turbine. The steam pipe P has a weld W in the circumferential direction of the pipe. Since the welding heat affected zone formed in the welded portion W has the highest creep damage progression rate, this embodiment evaluates the creep damage of the weld heat affected zone around the welded portion W. Therefore, the measurement projection 10 is formed on the outer peripheral surface of the steam pipe P with the weld W interposed therebetween.

  In the steam pipe P, stress in the radial direction, the circumferential direction, and the axial direction is generated by the high-pressure steam S flowing inside the steam pipe P. In addition, axial stress due to a bending moment is generated in the steam pipe P due to the weight of the steam pipe P and the thermal elongation of the piping system, or due to a load applied from the outside such as a support member. The measurement projection 10 is formed in advance on a portion where these loads are expected to be greatest and on the outer surface of the steam pipe P having a phase difference of 90 ° with the portion. The measurement projections 10 are arranged at equal intervals L from the welded portion W with the welded portion W interposed therebetween, and are arranged at 90 ° intervals at four locations in the circumferential direction.

  As shown in FIG. 2, the shape of the measurement protrusion 10 is a cylindrical shape, or the lower portion has a cylindrical shape and the upper portion has a frustoconical shape. Before starting the operation of the thermal power plant or during periodic inspection, the operator measures the distance 2L between the measurement projections facing each other with the weld W interposed therebetween using a micrometer or the like. In addition, after the start of operation, the interval 2L is periodically measured in addition to the periodic inspection.

  FIG. 3 is an enlarged cross-sectional view of the welded portion W of the steam pipe P. A weld heat affected zone HAZ is formed between the base material m of the steam pipe P and the weld metal w. The welding heat affected zone HAZ includes a coarse grain region r formed on the weld metal w side and a fine grain region f formed on the base material m side. Usually, creep voids are generated along the line AB in the fine-grained region f, which extends to the crack c and leads to fracture. As shown in FIG. 3, a creep strain that is larger in the interior than the surface of the steam pipe P occurs on the line AB. For this reason, the degree of creep damage is greater on the inside than on the surface.

  FIG. 4 shows a creep damage evaluation apparatus 12 according to this embodiment. Based on the past measurement values, a correlation map 14 indicating the correlation between the creep strain of the welding heat affected zone HAZ of the steam pipe P and the lifetime consumption rate is created in advance. The correlation map 14 is stored in the storage unit 16. In addition, the storage unit 16 stores a measurement value of the interval 2L measured before the start of boiler operation or during periodic inspection. An example of the correlation map 14 is shown in FIG. The creep strain measurement unit 18 receives a measurement value of an interval 2L that is periodically measured after the boiler operation is started. In the creep strain measuring unit 18, the measured value of the interval 2L measured before the start of operation of the boiler or at the periodic inspection is sent from the storage unit 16, and the creep strain of the interval 2L during operation is calculated.

The first estimation unit 20 uses the finite element method (FEM) to calculate the creep strain on the inner and outer surfaces of the welding heat affected zone HAZ and the inside of the plate thickness from the creep strain during the interval 2L. FIG. 5 (A) shows an example of a graph showing the creep strain between the outer surface and the plate thickness inside the weld heat affected zone HAZ thus obtained and the creep strain between the intervals 2L. The second estimator 22 receives the internal and external surfaces of the welding heat affected zone HAZ and the strain inside the plate thickness obtained by the first estimator 20 and the correlation map 14 from the storage unit 16. In the 2nd estimation part 22, the lifetime consumption rate of the inner and outer surfaces of the welding heat affected zone HAZ and the plate thickness is estimated from these input values. Thus, the obtained lifetime consumption rate is displayed on the display unit 24.

  About welded elbow of boiler steam piping (material: modified 9Cr steel, outer diameter / wall thickness: φ568.8 mm × t30 mm, curvature radius of bending portion: R840 mm, steam temperature: 650 ° C., steam pressure: 7.5 MPa) Experimental results obtained by the method of the first embodiment are shown in FIGS. FIG. 6 shows the relationship between the creep strain between the intervals 2L obtained by the first estimation unit 20 and the creep strains in the plate thickness inside and outside of the weld heat affected zone HAZ, and FIG. 7 shows the weld heat affected zone HAZ. It is a diagram which shows the relationship between the creep distortion of and the lifetime consumption rate of the welding heat affected zone HAZ.

  In the first embodiment, in addition to estimating the lifetime consumption rate of the steam pipe P by the method of the present invention, the conventional replica method and ultrasonic flaw detection method (TOFD method) are used in combination. As shown in FIG. 8, the distribution of creep voids on the outer surface of the steam pipe P is periodically observed by the replica method, the degree of creep damage on the outer surface of the steam pipe is determined, and the lifetime consumption rate of the outer surface of the steam pipe Predicted. In addition, the creep damage degree inside the plate thickness of the steam pipe P was determined by the TOFD method before starting the operation of the boiler or at the regular inspection and periodically thereafter, and the lifetime consumption rate inside the plate thickness was predicted. The results of life prediction by these methods are shown in the diagram of FIG.

  As described above, creep damage of the metal member proceeds faster inside than the surface. As shown in FIG. 8, the method of the present invention and the TOFD method that can determine the creep damage degree inside the thickness of the steam pipe P are determined in comparison with the replica method that can determine the creep damage degree of the surface of the steam pipe P. The remaining lifetime tends to be shortened.

  According to the present embodiment, the strain on the outer surface of the steam pipe P is measured, and the life consumption rate of the steam pipe P is estimated from the measured value. Therefore, the steam pipe made of 9-12Cr steel with less structural change due to creep damage. Even with P, the remaining life of the steam pipe P can be accurately estimated from the initial stage of the boiler operation. Moreover, since creep damage inside the plate thickness can also be estimated, the lifetime consumption rate can be determined more accurately than in the replica method or the like in which only the surface can be observed. Therefore, sufficient maintenance management time can be secured, and appropriate maintenance management can be performed.

  On the other hand, as shown in FIG. 8, the ultrasonic flaw detection method such as the TOFD method can determine the degree of creep damage only from the last stage where creep damage has progressed, so there is no time for maintenance management and appropriate maintenance management cannot be performed. There is a problem.

(Embodiment 2)
2nd Embodiment which applied this invention method and this invention apparatus to the steam piping which consists of 9-12Cr steel of the boiler for thermal power plants similar to 1st Embodiment is described based on FIGS. The creep damage evaluation apparatus of the present embodiment is the same as the creep damage evaluation apparatus 12 of the first embodiment. A tensile load F acts on the steam pipe P due to the high-pressure steam S flowing inside. The creep damage progression rate of the steam pipe P is substantially the same for the base material m and the weld metal w, and the weld heat affected zone HAZ is larger than these. Therefore, as the operation time becomes longer, the deformation of the welding heat affected zone HAZ becomes larger, and the dent δ is generated in the welding heat affected zone HAZ in the latter half of the life.

  The operator measures the indent δ and inputs the measured value to the strain measuring unit 18. As a method for measuring the indentation δ, for example, there is a measurement method using a micrometer or the like measured with a clay mold, or a measurement method using a laser microscope. The creep strain measuring unit 18 calculates the creep strain (indentation amount / thickness t of the steam pipe P) of the inner and outer surfaces of the welding heat affected zone HAZ from the measured value of the indentation amount of the indentation δ. The first estimation unit 20 calculates the creep strain inside and outside the weld heat affected zone HAZ and the inside of the plate thickness from the creep strain calculated by the creep strain measurement unit 18 using a finite element method (FEM). FIG. 10A shows an example of a graph showing the relationship between the indentation δ of the welding heat affected zone HAZ and the creep strain inside the outer surface of the welding heat affected zone HAZ and the plate thickness.

  The second estimation unit 22 receives the creep strain inside and outside the weld heat-affected zone HAZ obtained by the first estimation unit 20 and the creep thickness inside the plate thickness, and creates from the storage unit 16 based on the past measurement values. The correlation map 14 indicating the correlation between the creep strain of the weld heat affected zone HAZ of the steam pipe P and the life consumption rate is input in advance. FIG. 10B shows an example of the correlation map 14. In the 2nd estimation part 22, the lifetime consumption rate of the inner and outer surfaces of the welding heat affected zone HAZ and the plate thickness is estimated from these input values. Thus, the obtained lifetime consumption rate is displayed on the display unit 24.

  FIG. 11 shows the experimental results obtained by the method of the second embodiment for the welded elbow of the steam pipe for boiler. FIG. 11 shows the relationship between the indentation amount of the welding heat affected zone HAZ and the lifetime consumption rate obtained in the experiment. This lifetime consumption rate is predicted by the method of the second embodiment.

  According to the present embodiment, the amount of indentation on the outer surface of the weld heat affected zone HAZ of the steam pipe P is measured, and the life consumption rate of the steam pipe P is estimated from this measured value, so that there is little structural change due to creep damage. Even with the steam pipe P made of ˜12Cr steel, the remaining life of the steam pipe P can be accurately estimated from the initial stage of the operation start of the boiler. Therefore, sufficient maintenance management time can be secured, and appropriate maintenance management can be performed.

  In addition, this invention is applicable also to the creep damage evaluation of the metal member which consists of Cr steel with comparatively little Cr content, such as 2Cr steel.

  ADVANTAGE OF THE INVENTION According to this invention, the early detection of the creep damage of the metal member which consists of high Cr steels, such as 9-12Cr steel, is attained, and sufficient time for maintenance management can be ensured.

DESCRIPTION OF SYMBOLS 10 Measurement protrusion 12 Creep damage evaluation apparatus 14 Correlation map 16 Memory | storage part 18 Strain measurement part 20 1st estimation part 22 2nd estimation part 24 Display part F Tensile load HAZ Welding heat influence part P Steam piping S High pressure steam W Welding part c Crack f Fine grain region m Base material r Coarse grain region t Plate thickness w Weld metal δ Depression ε Creep strain

Claims (8)

From a past measurement value, a map creation step of creating a correlation map indicating the correlation between the creep strain of the metal member and the lifetime consumption rate due to creep damage;
A creep strain measuring step of measuring a displacement generated on the surface of the metal member and calculating a creep strain generated on the surface of the metal member from the displacement;
A first estimation step of estimating a creep strain inside the metal member by an analytical method from the creep strain measured in the creep strain measurement step;
A life consumption rate due to creep damage of the metal member is estimated based on the correlation map from the creep strain of the metal member surface measured in the creep strain measurement step and the creep strain inside the metal member estimated in the first estimation step. 2. A method for evaluating damage of a metal member, comprising: an estimation step.   In the creep strain measurement step, two or more measurement projections are formed in advance on the surface of the metal member, and the creep strain between the measurement projections is calculated from the distance between the measurement projections measured before and after the occurrence of the creep strain. The damage evaluation method for a metal member according to claim 1, wherein the damage evaluation method is used.   When a tensile load is applied to the metal member, the creep strain measurement step measures the depth of the recess generated on the surface of the metal member, and this measured value is an index of creep strain generated on the surface of the metal member. The damage evaluation method for a metal member according to claim 1.   A damage evaluation method for a metal member, wherein the damage evaluation method for a metal member according to claim 2 and claim 3 is used in combination.   In addition to the metal member damage evaluation method according to claim 1, a structure inspection of the surface of the metal member is performed, and the presence or absence of creep damage on the surface of the metal member is determined based on a result of the structure inspection. A damage evaluation method for a metal member, wherein the life consumption rate of the metal member is estimated from the life consumption rate estimated by the damage evaluation method according to 1. A correlation map created on the basis of past measurement values and showing a correlation between the creep strain of the metal member and the life consumption rate due to creep damage, and storage means for storing the correlation map;
A creep strain measuring means for inputting a displacement generated on the surface of the metal member and calculating a creep strain generated on the surface of the metal member from the displacement;
First estimation means for estimating the creep strain inside the metal member by an analytical method from the creep strain measured by the creep strain measurement means;
From the creep strain on the surface of the metal member measured by the creep strain measuring means and the creep strain inside the metal member estimated by the first estimating means, the lifetime consumption rate due to creep damage of the metal member is estimated based on the correlation map. A metal member damage evaluation apparatus comprising: a second estimation unit.   Provided with two or more measurement protrusions formed in advance on the surface of the metal member, and the distance between the measurement protrusions measured before and after the occurrence of the strain is input to the strain measurement means, and between the measurement protrusions by the strain measurement means 7. The damage evaluation apparatus for a metal member according to claim 6, wherein the creep strain is calculated.   The metal according to claim 6 or 7, wherein the measurement protrusions are arranged on both sides of the weld line of the metal member, and the life consumption rate due to creep damage of the heat affected zone of the weld line is estimated. Member damage evaluation device.

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