JP2015072170A - Method of evaluating life of weld member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of evaluating a life of a weld member, which is used in an environment where it is a high temperature and stress is loaded, and is capable of accurately evaluating the life of a weld member damaged by creep.SOLUTION: A method of evaluating a life of a weld member includes first creep damage degree diagnosis S10 including: a hardness detection step S11 of detecting hardness of a specific point of a weld member; a temperature estimation step S12 of acquiring a metal temperature at the specific point from the hardness detected by the hardness detection step on the basis of a preliminarily obtained relation between hardness variation and a softening parameter; a fracture time estimation step S13 of acquiring an estimated fracture time from design stress of the weld member and the metal temperature acquired in the temperature estimation step on the basis of a preliminarily obtained relation between stress and a creep evaluation parameter; and a first damage rate calculation step of acquiring, as a first damage rate, a value obtained by dividing a cumulative use time by the estimated fracture time.

Description

  The present invention relates to a method for evaluating the life of a welded member used in a high temperature and stressed environment.

  Generally, structural members such as piping and turbines of steam power plants are used in high temperature environments (up to about 600 ° C) and stress is applied. Creep damage occurs. In particular, when creep damage progresses, creep voids and microcracks are generated at the crystal grain boundaries of the structural member, and finally they are connected to form a crack, which may lead to damage. Therefore, in order to ensure the reliability of structural members used at high temperatures for stable operation of a power plant or the like, it is important to accurately evaluate creep damage and know the accurate life (creep life).

  As a method of evaluating the life of a structural member in which creep damage has occurred as described above, the structural member is examined for changes in the metal structure, changes in hardness, and the like. There is known a method for evaluating the life in accordance with the relationship between the above-mentioned grasped change amount of the metal structure or hardness change amount and the life.

  For example, in Patent Document 1, a replica method is used to observe a metal structure of a structural member to be evaluated, obtain a number density of voids (creep void number density) generated by creep, and a structure to be evaluated There is disclosed a method for evaluating the life of a member by evaluating the number of creep voids in association with the relationship between the number of creep voids previously determined by experiments in a laboratory or the like and the life of a structural member.

JP 2003-315251 A

  By the way, the structural member mentioned above may be made into the welding member which has a pair of base material and the welded joint which connects these. As a welding member, for example, in a turbine rotor, rotors having blades are joined together by a welded joint. In addition, the piping and the like have a structure joined to the passenger compartment and the valve body by a welded joint. In such a welded joint, there is a risk that the life of the welded heat affected zone near the welded joint may be reduced. However, a method for accurately evaluating the life of the welded member has not been established so far.

  Further, when the life of the welded member is evaluated using the method described in Patent Document 1 or when the life of the welded member is evaluated by a change in hardness, the amount of change depends on the difference in the material of the welded member, applied stress, and the like. May become smaller. That is, unless the end of the life of the welded member is reached, the amount of change cannot be grasped, and the accuracy of the life evaluation when the creep damage is small may be reduced.

  The present invention has been made in view of the above-described circumstances, and is used in a high temperature and stressed environment, and the life of a welded member capable of accurately evaluating the life of a welded member in which creep damage has occurred. The purpose is to provide an evaluation method.

  In order to solve the above-described problems, a welding member life evaluation method according to the present invention includes a pair of base materials and a welded joint connecting them, and is used in a state where high temperature and stress are applied. A method for evaluating the life of the welding member, the hardness detecting step for detecting the hardness of a specific portion of the welded member, and the specificity from the hardness detected by the hardness detecting step based on a relationship between a previously obtained hardness change and a softening parameter Based on the temperature estimation step for obtaining the metal temperature of the location and the relationship between the stress and the creep evaluation parameter obtained in advance, the estimated fracture time is obtained from the design stress of the welding member and the metal temperature obtained by the temperature estimation step. A first damage to damage, and a first damage rate calculation step for obtaining a value obtained by dividing the cumulative use time by the estimated break time as a first damage rate. It is characterized in that it comprises a diagnosis.

According to the weld member life evaluation method of the present invention, the first creep damage diagnosis is based on a hardness detection step of detecting the hardness of a specific portion of the weld member, and a relationship between a previously obtained hardness change and a softening parameter. The temperature estimation step of acquiring the metal temperature at a specific location from the hardness detected by the above-described hardness detection step can be obtained, so that the metal temperature when the welding member is used can be acquired. Next, the first creep damage level diagnosis is based on the relationship between the stress obtained until the weld member breaks in advance and the creep evaluation parameter, and the fracture time for obtaining the estimated break time from the design stress of the weld member and the aforementioned metal temperature. Therefore, it is possible to obtain the estimated fracture time of the welded member with high accuracy. The first creep damage degree diagnosis includes a first damage rate calculation step of acquiring a value obtained by dividing the cumulative use time of the welded member by the estimated fracture time obtained as described above as the first damage rate. The first damage rate can be obtained.
In this way, by obtaining a highly accurate damage rate, it is possible to accurately evaluate the life of the welded member. In addition, the method for evaluating the life of a welded member according to the present invention is applied to the case where it is difficult to actually measure the welded member because the life is evaluated by evaluating the change in hardness, not by actually measuring the metal temperature. can do.

Here, the design stress is a design stress set in an environment where the welding member is actually used. The metal temperature means the temperature of the welding member.
The softening parameter is a function of temperature and time. Specifically, the softening parameter is a function of the temperature when the welding member is placed in a high temperature environment and the time when the welding member is placed in the high temperature environment.
The creep evaluation parameter is also a function of temperature and time. Specifically, the temperature at which the welding member is placed in a high-temperature environment, and the welding member breaks in a state where a high temperature and a predetermined stress are applied. Is a function of the time until.

Further, the life evaluation method for a welded member according to the present invention includes a void amount detection step for detecting a void amount by conducting a structural investigation of a weld heat affected zone in the weld member, and a relationship between a void amount and a damage rate obtained in advance. Based on this, it is preferable to include a second creep damage degree diagnosis having a second damage rate calculation step of obtaining a second damage rate from the void amount detected by the void amount detection step.
In this case, based on the relationship between the void amount detection step for detecting the void amount in the weld heat affected zone of the welded member and the void amount and the damage rate obtained in advance, the void amount detected by the void amount detection step is secondly calculated. A second creep damage degree diagnosis having a second damage rate calculation step for obtaining a damage rate, and in addition to the first creep damage degree diagnosis, acquiring damage rates by a plurality of evaluation methods, and welding members Thus, the life evaluation accuracy can be further improved.

Moreover, it is preferable that the life evaluation method of the welding member of this invention performs life evaluation using the one with a larger damage rate among said 1st damage rate and said 2nd damage rate.
When evaluating the life of a welded member, the amount of change in hardness or the amount of change in voids may be reduced due to differences in the material of the welded member and applied stress, etc., and the accuracy of damage evaluation in low damage areas may be reduced. However, in this case, since the life evaluation is performed using the larger one of the first damage rate and the second damage rate, the accuracy of the life evaluation in the low damage region can be improved. it can. Further, by performing the life evaluation using the larger damage rate among the damage rates obtained by the plurality of evaluations as described above, a safer determination can be made when using the welded member.

In the welding member life evaluation method of the present invention, the specific portion may be a weld heat affected zone.
In this case, the temperature in the welding heat affected zone when the welding member is used in a high temperature environment can be acquired. Moreover, since the welding heat affected zone has a relatively large change in hardness in a high temperature environment, it is possible to accurately estimate the metal temperature of the welding member.

In the weld member life evaluation method of the present invention, the specific portion may be an evaluation weld metal portion provided in advance on the outer surface of the weld joint.
By adjusting the initial hardness of the weld metal portion for evaluation provided in advance on the outer surface of the weld joint to a predetermined hardness in advance, the temperature of the weld joint portion in a high temperature environment can be estimated more accurately. . For example, welded joints are used after being annealed, etc., with a lower hardness than during welding, but the strength of the weld metal part for evaluation should be set higher than that of the annealed welded joints. Thus, the amount of change in hardness that can be placed in a high-temperature environment can be increased, and the estimation accuracy of the metal temperature can be improved.

In the welding member life evaluation method of the present invention, the welding member is a turbine rotor in which a plurality of rotors having blades are welded by weld joints, and the specific portion is the rotor in a gap between adjacent blades. It may be a specimen for hardness measurement provided on the surface.
In this case, an accurate metal temperature can be obtained as described above by setting the hardness measurement test body provided on the rotor in the gap between adjacent blades as the above-mentioned specific location.
In addition, in the turbine rotor, the change in hardness and the amount of voids may be small in the low damage region. By evaluating the above-mentioned first damage rate and second damage rate, the life evaluation in the low damage region can be performed. Accuracy can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the lifetime evaluation method of the welding member which can be used in the environment where high temperature and stress were loaded, and can evaluate the lifetime of the welding member which the creep damage generate | occur | produced can be provided accurately.

It is a schematic explanatory drawing of the turbine rotor (welding member) which the evaluation method of the lifetime evaluation of the welding member which concerns on 1st embodiment of this invention makes the object of evaluation. It is a flowchart of the lifetime evaluation method of the turbine rotor (welding member) which concerns on 1st embodiment of this invention. It is a figure which shows the relationship between the hardness and measurement position in the turbine rotor (welding member) which concern on 1st embodiment. It is a figure which shows the relationship between the ratio of the hardness of the HAZ part before and after a creep test, and a softening parameter. It is a figure which shows the relationship between the stress applied to a turbine rotor (welding member) in a creep test, and a creep evaluation parameter. It is a figure which shows the relationship between the void number density and damage rate in a creep test. It is a schematic explanatory drawing of the turbine rotor (welding member) made into the evaluation object by the lifetime evaluation method of the welding member which concerns on 2nd embodiment of this invention. It is a flowchart of the lifetime evaluation method of the turbine rotor (welding member) which concerns on 2nd embodiment of this invention. It is a figure which shows the relationship between the hardness and measurement position in the turbine rotor (welding member) which concern on 2nd embodiment. It is a flowchart of the lifetime evaluation method of the turbine rotor (welding member) which concerns on 3rd embodiment of this invention.

(First embodiment)
Below, the lifetime evaluation method of the welding member which concerns on embodiment of this invention is demonstrated with reference to attached drawing.
First, the turbine rotor 10 (welding member) to be evaluated by the welding member life evaluation method according to the embodiment of the present invention will be described. As shown in FIG. 1, the turbine rotor 10 is configured by welding a plurality of rotors 11 (base materials) having blades (not shown) with welded joints 12 (welded metal portions). As shown in FIG. 1, in the welded portion of the pair of rotors 11 and 11 (base material), a welding heat affected zone 13 (HAZ portion) is formed on the rotor 11 side at the joint interface between the rotor 11 and the welded joint 12. Has been.

The material of the rotor 11 is made of, for example, low alloy steel, high chromium steel, Ni-base superalloy, or the like. In the present embodiment, of the pair of rotors 11, one rotor 11 is made of low alloy steel, and the other rotor 11 is made of high chromium steel.
The material of the welded joint 12 (welded metal part) is the same material as the base material, and is composed of, for example, low alloy steel, high chromium steel, Ni-base superalloy, or the like.

The above-described turbine rotor 10 is a turbine rotor 10 used for, for example, a steam turbine, and is currently used in a high temperature environment of about 600 ° C. at the maximum. Further, since the turbine rotor 10 is rotated and used in a high temperature environment, centrifugal force acts and stress is applied to the turbine rotor 10.
Thus, the turbine rotor 10 that is used in a state of being loaded with high temperature and stress is damaged by creep. The weld member life evaluation method according to the present embodiment is for evaluating the life of the turbine rotor 10 (weld member) in which damage due to creep has occurred.

Next, the welding member life evaluation method according to the first embodiment of the present invention will be described with reference to FIGS.
The weld member life evaluation method according to the first embodiment includes a first creep damage degree diagnosis S10 and a second creep damage degree diagnosis S20, and the life of the turbine rotor 10 (welding member) is grasped based on these results. To do.

  First, the first creep damage diagnosis S10 will be described. The first creep damage degree diagnosis S10 includes a hardness detection step S11, a temperature estimation step S12, a fracture time estimation step S13, and a first damage rate calculation step S14. Details of each step will be described below.

(Hardness detection step S11)
In the first creep damage degree diagnosis S10, first, a hardness detection step S11 is performed. The hardness detection step S11 is a step of detecting (obtaining) the hardness by measuring the hardness of the turbine rotor 10 before and after operation. In this embodiment, the Vickers hardness on the broken line shown in FIG. Yes. Here, the hardness before and after the operation of the turbine rotor 10 means the hardness before the turbine rotor 10 is used and the hardness after the turbine rotor 10 is operated and creep damage occurs.

  An example of the measurement result is shown in FIG. Note that the hardness measurement results shown in FIG. 3 are the hardness measurement results before the turbine rotor 10 is operated. In the present embodiment, temperature estimation is performed using the hardness at the position indicated by the arrow B in FIG. The location indicated by the arrow B is the position with the highest hardness in the welding heat affected zone 13 (HAZ portion).

(Temperature estimation step S12)
Next, a temperature estimation step S12 is performed. This temperature estimation step S12 is a step of grasping the metal temperature of the turbine rotor 10 when the turbine rotor 10 is operated. Here, the metal temperature means not the atmospheric temperature but the temperature of the turbine rotor 10.
Specifically, the temperature estimation step S12 is detected by the hardness detection step S11 described above based on the relationship between the hardness change obtained in advance and the softening parameter that is a function of temperature and time (curve C in FIG. 4). In this step, the metal temperature at the specific location is obtained from the hardness. The softening parameter is expressed by LMP (Larson-Miller Parameter) and is generally represented by LMP = T * (logt + α) (T: temperature, t: time, α: constant). Here, the constant α may be set to 20, for example.

  Here, the relationship between the hardness change obtained in advance and the softening parameter is obtained in advance by an experiment in a laboratory. For example, in the laboratory, welding similar to that of the turbine rotor 10 to be subjected to life evaluation is performed. A creep test or a long-time heating test is performed using a test piece having a part as a test piece, and can be obtained by a relationship between a change in hardness and a softening parameter that is a function of temperature and time in the test. In FIG. 4, the vertical axis represents the change in hardness, which is the ratio between the hardness HV of the test piece (welded member) after heating and the hardness HV0 before heating. The horizontal axis is a softening parameter that is a function of heating temperature and time.

  The method for estimating the metal temperature will be described in detail. HV / HV0 (Y1) of the turbine rotor 10 at the position indicated by the arrow B is obtained, and the value of X1 is obtained by making Y1 correspond to the curve C. Then, the metal temperature T1 of the turbine rotor 10 is calculated from the relationship between the value of X1 and the softening parameter and the operation time of the turbine rotor 10.

(Breaking time estimation step S13)
Next, a fracture time estimation step S13 is performed. In the fracture time estimation step S13, based on the relationship between the stress obtained in advance and LMP (Larson-Miller Parameter) which is a function of time and temperature as a creep evaluation parameter (curve D in FIG. 5), In this step, an estimated fracture time is obtained from the design stress and the metal temperature obtained in the temperature estimation step S12.

Here, curve D in FIG. 5 shows a test piece having a welded portion similar to that of turbine rotor 10 that is the object of life evaluation, until a fracture occurs when a creep test is performed under various stresses. It can be obtained by calculating the time. The creep evaluation parameter is a function of the temperature at which the aforementioned test piece is subjected to a creep test and the temperature until the test piece breaks.
The method for estimating the fracture time will be described in detail. The design stress Y2 of the turbine rotor 10 is made to correspond to the curve D to obtain the creep evaluation parameter value X2, the relationship between the value of X2 and the creep evaluation parameter, the temperature An estimated fracture time is obtained from the relationship of the metal temperature T1 obtained in the estimation step S12.

(First damage rate calculation step S14)
Next, a first damage rate calculation step S14 is performed. The first damage rate calculation step S14 is a step of acquiring a value obtained by dividing the cumulative use time by the estimated break time as the first damage rate. The first damage rate is a creep damage rate of the turbine rotor 10 when the turbine rotor 10 is damaged by operating.
The first damage rate is calculated as described above.

  Next, the second creep damage degree diagnosis S20 will be described. The second creep damage level diagnosis S20 includes a void amount detection step S21 and a second damage rate calculation step S22. Details of each step will be described below.

(Void amount detection step S21)
In the second creep damage level diagnosis S20, a void amount detection step S21 is first performed. This void amount detection step S21 is a step of detecting the void amount by conducting a structural investigation of the welding heat affected zone 13 of the turbine rotor 10. Specific examples of the void amount include, for example, the number density of voids and the area ratio of voids. In this embodiment, the number density of voids is detected as the void amount.
As the void evaluation method, for example, a replica method can be used. In the replica method, the irregularities corresponding to the metal structure of the surface of the measurement target area that has been exposed after a predetermined treatment are transferred to a film, and the transferred irregularities are observed with a microscope using an optical microscope or a scanning electron microscope. For example, the observed creep voids can be measured as the number of voids per predetermined area.

(Second damage rate calculation step S22)
Next, a second damage rate calculation step S22 is performed. In the second damage rate calculation step S22, the second damage rate is acquired from the void amount detected in the void amount detection step S21 based on the relationship between the void amount and the damage rate (curve E shown in FIG. 6) obtained in advance. It is a process to do.
If the curve E is acquired in advance in a laboratory, for example, by performing a creep test using a specimen having a welded portion similar to that of the turbine rotor 10 to be evaluated for life evaluation, and measuring the void number density. Good.
The calculation method of the second damage rate will be specifically described. The second damage rate X3 is calculated by causing the void number density Y3 obtained in the void amount detection step S21 to correspond to the curve E.

As described above, the first damage rate and the second damage rate can be acquired. In this embodiment, it is set as the structure which selects the larger one among a 1st damage rate and a 2nd damage rate, and grasps | ascertains the lifetime of the turbine rotor 10. FIG.
As described above, the life evaluation method for the turbine rotor 10 (welding member) according to the present embodiment is completed.

According to the method for evaluating the life of the welded member (turbine rotor) according to the present embodiment configured as described above, the first creep damage degree diagnosis S10 includes a hardness detection step S11 and a temperature estimation step S12. Therefore, the metal temperature when the turbine rotor 10 is used can be acquired.
Further, the first creep damage diagnosis S10 includes a rupture time estimation step S13 for obtaining an estimated rupture time from the design stress of the turbine rotor 10 and the above-described metal temperature based on the relationship between the stress obtained in advance and the softening parameter. Therefore, it is possible to obtain an accurate estimated break time. Then, the first creep damage degree diagnosis S10 divides the accumulated usage time of the turbine rotor 10 by the estimated break time obtained as described above, and obtains this value as the first damage rate in a first damage rate calculation step S14. Therefore, the first damage rate which is the creep damage rate can be acquired.
In this way, it is possible to accurately evaluate the life of the turbine rotor 10 (welding member) by acquiring an accurate damage rate.

  Moreover, the lifetime evaluation method of the welding member which concerns on this embodiment is the void amount detection process S21 which detects the void amount of the welding heat affected zone 13 in the welding part of the turbine rotor 10, and the void amount and damage rate which were calculated | required previously. Since the second creep damage degree diagnosis S20 having the second damage rate calculation step S22 for obtaining the second damage rate from the void amount detected by the void amount detection step S21 based on the relationship is provided, the first creep damage is provided. In combination with the degree diagnosis S10, it is possible to acquire damage rates by a plurality of evaluation methods, evaluate the life of the welded member, and further improve the accuracy of the life evaluation.

  When evaluating the life of the turbine rotor 10, the amount of change in hardness or the amount of void becomes small due to the difference in the material of the rotor 11 and the welded joint 12, the applied stress, etc., and the accuracy of damage evaluation in a low damage region May be low. However, the life evaluation method for the welded member according to the present embodiment is configured to perform the life evaluation using the larger damage rate of the first damage rate and the second damage rate. The accuracy of life evaluation in the damaged area can be improved.

  Moreover, in the lifetime evaluation method of the welding member which concerns on this embodiment, since it is set as the structure in which a hardness test is performed to the welding heat influence part 13, the welding heat influence part when the turbine rotor 10 is used in a high temperature environment. The metal temperature at 13 can be obtained. Further, since the welding heat affected zone 13 has a relatively large amount of change in hardness in a high temperature environment, the metal temperature of the turbine rotor 10 can be accurately estimated. Furthermore, in the present embodiment, the welding heat-affected zone 13 is configured to measure the hardness change at the high hardness position shown by B in FIG. 3, so that a relatively large hardness change can be obtained. Metal temperature estimation accuracy is improved.

(Second embodiment)
Next, the welding member evaluation method according to the second embodiment of the present invention will be described. In the second embodiment, the same components as those of the welding member evaluation method described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 7, the turbine rotor 110 (welding member) to be evaluated by the welding member life evaluation method according to the second embodiment includes a plurality of rotors 11 (base materials) including welded joints 12 (welded metal). Part). As shown in FIG. 7, in the welded portion of the pair of rotors 11 (base material), a welding heat affected zone 13 is formed on the rotor 11 side at the joint interface between the rotor 11 and the welded joint 12. In the present embodiment, the weld metal portion 114 for evaluation is formed in advance on a part of the outer peripheral surface of the weld joint 12. The welded joint 12 is used after being annealed because of its high hardness after welding, but the evaluation weld metal part 114 is set to have a higher hardness than the welded joint 12.

Next, a method for evaluating the life of a welded member according to a second embodiment of the present invention will be described with reference to FIGS.
The weld member life evaluation method according to the second embodiment includes a first creep damage degree diagnosis S110 and a second creep damage degree diagnosis S20, and the life of the turbine rotor 110 (welding member) is grasped based on these results. To do. The second creep damage level diagnosis S20 has the same configuration as that described in the first embodiment, and thus detailed description thereof is omitted.

  In the second embodiment, the first creep damage degree diagnosis S110 includes a hardness detection step S111, a temperature estimation step S12, a fracture time estimation step S13, and a first damage rate calculation step S14. In addition, processes other than hardness detection process S111 are the structures similar to 1st embodiment.

(Hardness detection step S111)
In the first creep damage degree diagnosis S110, first, a hardness detection step S111 is performed. The hardness detection step S111 is a step of measuring the hardness before and after the operation of the turbine rotor 110 to detect (obtain) the hardness. In the present embodiment, the Vickers hardness on the broken line shown in F of FIG. 7 is measured. Yes.
An example of the measurement result is shown in FIG. The hardness measurement results shown in FIG. 9 are the hardness measurement results before the turbine rotor 110 is operated. In the second embodiment, temperature estimation is performed using the hardness of the weld metal part 114 for evaluation of the turbine rotor 110 in the temperature estimation step S12. As shown in FIG. 9, the evaluation weld metal portion 114 has a higher hardness than the weld joint 12.

  Next, a temperature estimation step S12, a rupture time estimation step S13, and a first damage rate calculation step S14 are sequentially performed to calculate a first damage rate.

Also in the second embodiment, as in the first embodiment, the first damage rate and the second damage rate are acquired, and the larger one of the first damage rate and the second damage rate is selected, and the turbine rotor is selected. Know the life of 110.
As described above, the life evaluation method for the welded member (turbine rotor 110) according to the present embodiment is completed.

  According to the life evaluation method of the welding member (turbine rotor 110) according to the second embodiment configured as described above, the hardness of the weld metal portion 114 for evaluation provided in advance on the outer surface of the weld joint 12 is Since the hardness is set to be higher than that of the welded joint 12, the hardness change due to creep can be increased, and the metal temperature of the turbine rotor 110 can be estimated with higher accuracy. As described above, the estimation accuracy of the metal temperature is improved, so that the lifetime can be evaluated with high accuracy.

(Third embodiment)
Next, a method for evaluating a welded member according to the third embodiment of the present invention will be described. In the third embodiment, the same components as those of the welding member evaluation method described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the turbine rotor (welding member) to be evaluated by the weld member life evaluation method according to the third embodiment, a plurality of rotors (base materials) having blades are welded by a welded joint (welded metal part). It is constituted by. In the welded portion of the pair of rotors (base materials), a weld heat affected zone is formed on the rotor side at the joint interface between the rotor and the welded joint. And in 3rd embodiment, the test body for hardness measurement is previously provided in the rotor (near the welded joint) in the gap | interval of an adjacent blade | wing.

Next, a method for evaluating the life of a welded member according to a third embodiment of the present invention will be described with reference to FIG.
The weld member life evaluation method according to the third embodiment includes a first creep damage degree diagnosis S210 and a second creep damage degree diagnosis S20. Based on these results, the life of the turbine rotor (welding member) is grasped. Is. The second creep damage level diagnosis S20 has the same configuration as that described in the first embodiment, and thus detailed description thereof is omitted.

  In the third embodiment, the first creep damage degree diagnosis S210 includes a hardness detection step S211, a temperature estimation step S12, a fracture time estimation step S13, and a first damage rate calculation step S14. Details of the hardness detection step S211 will be described below.

(Hardness detection step S211)
In the first creep damage level diagnosis S210, first, a hardness detection step S211 is performed. The hardness detection step S211 is a step of measuring the hardness of the turbine rotor before and after operation and detecting (obtaining) the hardness. In the third embodiment, the hardness change of a specimen for hardness measurement provided in advance is acquired. To do.
Next, a temperature estimation step S12, a rupture time estimation step S13, and a first damage rate calculation step S14 are sequentially performed to calculate a first damage rate.

In the third embodiment, as in the first embodiment, the first damage rate and the second damage rate are acquired, and the larger one of the first damage rate and the second damage rate is selected, and the turbine rotor Know life.
As described above, the life evaluation method for the welding member (turbine rotor) according to the present embodiment is completed.

  According to the method for evaluating the life of the welded member (turbine rotor) according to the third embodiment having the above-described configuration, the hardness measurement specimen is provided in advance in the rotor. By measuring, a precise metal temperature can be obtained.

  As mentioned above, although the lifetime evaluation method of the welding member which is embodiment of this invention was demonstrated, this invention is not limited to this, In the range which does not deviate from the technical idea of this invention, it can change suitably.

In the said embodiment, although the lifetime evaluation method of the welding member demonstrated the structure provided with a 1st creep damage degree diagnosis and a 2nd creep damage degree diagnosis, it is not limited to this, The life of a welding member The evaluation method may be configured to include only the first creep damage degree diagnosis.
In addition, the life evaluation method of the welded member has been described for the case where the first damage rate and the second damage rate are calculated and the life is evaluated using the one with the larger damage rate, but is not limited thereto. For example, according to a predetermined standard, it is good also as a structure which selects either damage rate and evaluates a lifetime.

10, 110 Turbine rotor 11 Rotor 12 Welded joint (welded metal part)
13 Welding heat affected zone 114 Weld metal parts for evaluation S10, S110, S210 First creep damage degree diagnosis S11, S111, S211 Hardness detection step S12 Temperature estimation step S13 Break time estimation step S14 First damage rate calculation step S20 Second creep Damage degree diagnosis S21 Void amount detection step S22 Second damage rate calculation step

Claims (6)

It has a pair of base materials and a welded joint that connects them, and is a life evaluation method for a welded member that is used in a state in which high temperature and stress are applied,
A hardness detection step of detecting the hardness of the specific location of the weld member;
Based on the relationship between the hardness change obtained in advance and the softening parameter, a temperature estimation step of obtaining the metal temperature of the specific location from the hardness detected by the hardness detection step;
Based on the relationship between the stress obtained in advance and the creep evaluation parameter, a fracture time estimation step for obtaining an estimated fracture time from the design temperature of the weld member and the metal temperature obtained by the temperature estimation step;
A first creep damage degree diagnosis method comprising: a first damage rate calculation step of acquiring a value obtained by dividing a cumulative use time by the estimated breakage time as a first damage rate. Conducting a structure survey of the weld heat affected zone in the welded member, and detecting a void amount,
A second damage rate calculation step of acquiring a second damage rate from the void amount detected by the void amount detection step based on a relationship between a void amount and a damage rate obtained in advance, and a second creep damage degree diagnosis having The life evaluation method of the welding member according to claim 1, comprising:   The life evaluation method for a welded member according to claim 2, wherein the life evaluation is performed using the larger one of the first damage rate and the second damage rate.   The said specific location is a welding heat affected zone, The lifetime evaluation method of the welding member as described in any one of Claims 1-3 characterized by the above-mentioned.   The method for evaluating the life of a welded member according to any one of claims 1 to 3, wherein the specific location is an evaluation weld metal portion provided in advance on an outer surface of the weld joint. The welding member is a turbine rotor in which a plurality of rotors having blades are welded by weld joints,
The lifetime of the welding member according to any one of claims 1 to 3, wherein the specific location is a hardness measurement specimen provided in the rotor in a gap between adjacent blades. Evaluation method.

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