JP3533517B2 - Life prediction method for high temperature parts - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for predicting the life of a high temperature member, and particularly to a high temperature member containing a metal material, for example, a turbine rotor used in a steam turbine, a turbine casing and a main valve casing. The present invention relates to a method for predicting the life of a high temperature member suitable for predicting the life of a high temperature member constituting a high temperature device.

[0002]

2. Description of the Related Art High-temperature members used in high-temperature equipment such as thermal power, nuclear power, and chemical plants are subjected to external force at high temperatures, and their life may be damaged or their materials may deteriorate during long-term use. Need to be replaced).

In order to determine the replacement time, it is necessary to obtain the life damage degree of the high temperature equipment used for a long time by some method.

Conventionally, in order to determine the degree of damage to the life of high-temperature equipment, a method has been employed in which a test piece is directly cut out from a member that has been used for a long time and a breaking test is performed. But,
With this method, the degree of life damage cannot be measured nondestructively, and there are drawbacks such as 1) the parts must be broken, and 2) it takes time.

On the other hand, in recent years, large-scale thermal power plants have been frequently started and stopped and the load is changed, and it is necessary to endure more severe operating conditions. When such an operation is performed, in addition to centrifugal force due to high-speed rotation or internal pressure stress due to high-pressure steam, complicated thermal stress acts on the high-temperature member constituting the steam turbine, so that life consumption is accelerated. Therefore, the service life may be shorter than the service life due to the simple design use temperature, time and stress.

Further, more than half of the high-temperature equipment installed in the thermal power plants of Japan have been operated for 100,000 hours or more, and these high-temperature equipment are reaching the end of their useful lives. Therefore, it is important to accurately determine the remaining life of high-temperature equipment that has been operating for a long time and is approaching the end of its useful life. As a method for that, a nondestructive method has been developed in recent years.

As a method of measuring the remaining life of high temperature equipment by a nondestructive and simple method, for example, Japanese Patent Publication No. 2-545
As described in JP-A-14, the hardness of a metal material member used at a high temperature is measured, and the difference between the measured value and the hardness when used in an unloaded state at the operating temperature and time. Has been proposed, and the creep strain damage ratio is calculated based on this difference, and the residual life is calculated from the creep strain damage ratio and the creep time damage ratio.

[0008]

DISCLOSURE OF THE INVENTION In the prior art,
The creep damage rate is calculated from the decrease in hardness of the member used at high temperature, and the residual life is predicted based on this creep damage rate.Therefore, the residual life of high temperature equipment should be calculated by a non-destructive method. You can However, in order to obtain the creep damage rate, it is necessary to measure the initial hardness of the member used at high temperature, and if the initial hardness is not measured during manufacturing, it is possible to estimate the initial hardness. To be forced. Moreover, in equipment such as turbine rotors,
Since the hardness of each part at the time of manufacturing varies, even if the initial hardness is estimated, the accuracy of the estimated value decreases, and it becomes difficult to calculate the creep damage rate with high accuracy.

It is an object of the present invention to provide a method for predicting the life of a high temperature member which can predict the life of the high temperature member with high accuracy without using the initial hardness of the high temperature member.

[0010]

In order to achieve the above object, the present invention provides a method for measuring the hardness of an evaluation portion of a measurement site of a high temperature member containing a metallic material, which is subject to creep damage due to temperature and time passage. Measured a plurality of times, to calculate the hardness decrease amount due to creep damage of the evaluation part after a lapse of a certain time corresponding to the time interval based on the difference of each measurement value related to the evaluation part, and this was calculated. The amount of creep damage accumulated for the time interval is calculated from the hardness decrease amount and the time interval, and from the time ratio of the time corresponding to the end of the time interval and the time interval and the calculated creep damage accumulated amount. The creep damage rate of the evaluation unit is calculated, and a life prediction method for a high temperature member is adopted to predict the life of the high temperature member according to the calculation result.

According to the above-mentioned means, the hardness of the evaluation part is
Measure multiple times at time intervals, calculate the amount of hardness decrease due to creep damage in the evaluation part after a certain time corresponding to the time interval based on the difference between each measured value for the evaluation part, and use this calculated value as the basis. Since the creep damage accumulation amount for the time interval is calculated and the creep damage rate of the evaluation part is calculated based on this calculated value, the creep damage of the evaluation part is not used without using the initial hardness of the evaluation part. According to the calculation result of the rate, the life of the high temperature member can be predicted with high accuracy.

When the method for predicting the life of the high temperature member is adopted, the hardness decrease amount of the evaluation portion is calculated, and the hardness of the no-load heating material is calculated a plurality of times corresponding to the time interval, Calculate the hardness decrease amount of the no-load heating material after a certain period of time corresponding to the time interval from the difference between the calculated values for the load heating material, and the calculated hardness decrease amount of the evaluation unit and the calculated It is also possible to calculate the amount of creep damage accumulated for the time interval from the amount of decrease in hardness due to creep damage showing the difference from the amount of decrease in hardness of the unloaded heating material and the time interval. In this case, the creep damage accumulation amount for the time interval is calculated based on the hardness decrease amount due to creep damage, which indicates the difference between the hardness decrease amount of the evaluation part and the hardness decrease amount of the unloaded heating material. The accuracy of the calculated value relating to the accumulated amount of creep damage for the time interval can be increased more than when the hardness decrease amount due to creep damage of the evaluation part is calculated based on the difference between the measured hardness values of the evaluation part.

When adopting the method of predicting the life of the high temperature member, the following elements can be added.

(1) A residual life is predicted as a life for the high temperature member from the calculated value relating to the creep damage rate of the evaluation section and the time corresponding to the end of the time interval.

(2) The hardness of the reference portion is measured a plurality of times corresponding to the time intervals, with a reference portion being a portion which is not subject to creep damage due to temperature and elapsed time among the measurement portions of the high temperature member. The hardness decrease amount due to the creep damage is corrected based on the difference between the respective measured values.

Further, according to the present invention, when estimating the initial hardness of the evaluation part, the hardness of the evaluation part which is subject to creep damage due to temperature and the passage of time is selected from the measurement parts of the high temperature member containing the metal material at time intervals. Measured a plurality of times, calculate the hardness decrease amount of the evaluation part after a certain time corresponding to the time interval from the difference between the respective measured values for the evaluation part, and the calculated value and the creep damage of the evaluation part. The life prediction method of the high temperature member for estimating the initial hardness of the evaluation part from the rate is adopted.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of a measurement target to which the present invention is applied. In FIG. 1, a turbine rotor 10
Is provided with a high temperature first stage section 12 and a coupling section 14 as one element of high temperature equipment used in a steam turbine. The turbine rotor 10 has a high temperature, for example, 4
A metal material used in an atmosphere of 50 ° C. or higher, for example,
It is composed of a high-temperature member containing Cr-Mo-V steel. When this turbine rotor 10 is used as a measurement target, an evaluation unit that is subject to creep damage due to temperature and time elapses out of measurement portions of each unit of the turbine rotor 10 is a high pressure first stage unit 12.
Then, a method of predicting the life of this evaluation unit will be described below.

Prior to predicting the life of the high-pressure first stage section (evaluation section) 12, the turbine rotor material Cr is used.
As a no-load heating test for unused Mo-V steel, heat treatment was performed with the temperature and time varied in the heating temperature range of 450 to 600 ° C., and the Vickers hardness (Hvh) of the unused material after heating Was measured. This change in hardness indicates the degree of change in the metallurgical structure during heating at high temperature for a long time. As shown in FIG. 2, the vertical axis represents hardness (Vickers hardness) and the horizontal axis represents heating condition parameter P. [P = T (C +
log t)], the experimental points are plotted and the heating condition parameter P is set regardless of the heating temperature and time.
When the value of exceeds a certain value, it is represented by a curve (no-load heating material master curve). From this curve, the hardness (Hvh) when heated for a long time with no load can be obtained by giving the operating temperature and the operating time.

Next, a method of predicting the life of the high-pressure first stage section 12 after operating the steam turbine will be described with reference to the flowchart of FIG.

First, when a certain time (operating time: t1 hour) has elapsed from the start of operation after the steam turbine was operated at a specified temperature, for example, 525 ° C., the high pressure first stage section (evaluation section) 12 at t1 hour Hardness (Vickers hardness)
To measure. When the hardness at this time is Hvc1, the value of hardness Hvc1 can be plotted in FIG. 2 as the point corresponding to the heating condition parameter P1 from the operating temperature and the operating time. Thereafter, at a time t2 after a lapse of a certain time with a time interval from the time t1, the high pressure first stage unit 1
The hardness of two identical parts is measured. When the hardness (Vickers hardness) at this time is Hvc2, the point of hardness Hvc2 can be plotted in FIG. 2 corresponding to the heating condition parameter P2 from the operating temperature and the operating time (step S).
1).

Next, heating condition parameters P1 and P2
Corresponding to the hardness of the no-load heating material (Hvh1 and Hvh
2) is calculated based on the curve of FIG. 2 (step S2).

Next, the hardness decrease amount ΔHx = Hvc1−Hvc of the high-pressure first-stage part (evaluation part) 12 after a certain time corresponding to the time interval (time interval from t1 to t2).
2 is calculated (step S3). Then, the hardness decrease amount a = Hvh1− of the unloaded heating material after a certain period of time corresponding to the time interval (time interval from time t1 to t2).
Hvh2 is calculated (step S4).

Thereafter, based on the hardness decrease amount calculated in steps S3 and S4, the hardness decrease amount ΔH'x due to the creep damage accumulated from the operating time t1 to t2.
= ΔHx-a is calculated (step S5).

Next, the creep damage accumulation amount ΔφCL for the time interval (the time interval from the time t1 to t2) is calculated from the time interval from the operation time t1 to t2 and the hardness decrease amount ΔH'x due to the creep damage. Yes (step S6). This creep damage accumulated amount ΔφCL is, as shown in FIG.
Since the hardness decrease amount ΔH′x decreased due to creep damage and the creep damage rate are in direct proportion (see the straight line shown in FIG. 4), the hardness decrease amount ΔH′x due to creep damage is Δt time (operating time t1. To the time t2), the creep damage accumulated amount ΔφCL can be obtained.

Since the creep damage rate φCL is expressed by a time ratio related to the creep damage accumulated amount ΔφCL as shown in the following equation (1), the operation time t2 from the start of the operation of the steam turbine and the time interval (at the time of measurement) ( Δt = t2-t1)
Can be obtained by the time ratio (step S7).

ΦCL = ΔφCL × (t2 / Δt) (1) After the creep damage rate φCL is obtained, the remaining life tx can be obtained according to the following equation (2).

Tx = t (1 / φCL-1) (2) where t: operating time of high temperature member As described above, according to this embodiment, the initial hardness of the high pressure first stage portion 12, that is, at the time of manufacture. Even if the hardness of the high-pressure first-stage portion 12 is unknown, the creep damage rate of the high-pressure first-stage portion 12 can be calculated only by measuring the hardness twice at the same portion of the high-pressure first-stage portion 12, and according to the calculation result, The life can be predicted with high accuracy.

In the above embodiment, the high pressure initial stage section 12
Since the hardness is measured twice, the time interval for measuring the hardness is long, and it is possible that the hardness measuring equipment used is different. Therefore, not only the hardness of the high-pressure first-stage section 12 is measured, The coupling portion 14 is set as a reference portion, that is, a reference portion that is not damaged by creep due to temperature and time is set in the coupling portion 14.
Is measured at the same time intervals as the high-pressure first-stage section 12, and the hardness decrease amount ΔH′x is corrected based on the difference between the measured values.
In addition to being able to correct instrumental differences in hardness measuring equipment,
The measurement accuracy can be improved.

In the above embodiment, when the hardness decrease amount ΔH'x due to creep damage is calculated, the hardness decrease amount aH of the no-load heating material is subtracted from the hardness decrease amount ΔHx of the high pressure first stage section 12. Therefore, the high pressure first stage 12
The accuracy can be improved more than when the creep damage accumulation amount for the Δt time is calculated directly from the hardness decrease amount ΔHx.

When the hardness decrease amount a of the no-load heating material is small (when it is a negligible value), the amount of creep damage accumulated for Δt time is directly calculated from the hardness decrease amount ΔHx of the high-pressure first-stage part 12. Can also be calculated.

In the above embodiment, the hardness of the high-pressure first-stage portion 12 is measured twice, but the hardness of the high-pressure first-stage portion 12 can be measured twice or more.
When performing the measurement more than once, the initial hardness of the high-pressure first-stage portion 12 is unknown by determining the hardness of the high-pressure first-stage portion 12 and the hardness of the unloaded heating material at each measured time interval as in the above embodiment. Even so, the creep damage rate of the high-pressure first-stage portion 12 can be calculated with high accuracy.

When the creep damage rate of the high-pressure first-stage section 12 is obtained by the life prediction method of the above-described embodiment, or when the creep damage rate of the high-pressure first-stage section 12 is obtained by the resistance measurement method, the high-pressure first-stage section 12 is obtained. Hardness is measured a plurality of times at time intervals, and the hardness decrease amount of the high-pressure first-stage part 12 after a lapse of a fixed time corresponding to the time interval is calculated from the difference between the measured values, and the calculated value and the high-pressure first-stage part are calculated. It is also possible to estimate the initial hardness of the high-pressure first-stage part 12 from the creep damage rate of 12.

[0033]

As described above, according to the present invention,
The hardness of the evaluation part is measured multiple times at time intervals, and the amount of decrease in hardness due to creep damage of the evaluation part after a lapse of a certain time corresponding to the time interval is calculated based on the difference of each measurement value related to the evaluation part. However, since the creep damage accumulation amount for the time interval is calculated based on this calculated value, and the creep damage rate of the evaluation part is calculated based on this calculated value, the initial hardness of the evaluation part should be used. Instead, the life of the high temperature member can be predicted with high accuracy according to the calculation result of the creep damage rate of the evaluation unit.

[Brief description of drawings]

FIG. 1 is a front view of a turbine rotor to which the present invention is applied.

FIG. 2 is a characteristic diagram showing a relationship between hardness and heating condition parameters.

FIG. 3 is a flowchart for explaining a life prediction method according to the present invention.

FIG. 4 is a characteristic diagram showing a relationship between a hardness decrease amount due to creep damage and a creep damage rate.

[Explanation of symbols]

10 turbine rotor 12 High pressure first stage 14 Coupling part

Continuation of the front page (56) Reference JP-A-58-92952 (JP, A) JP-A-7-128328 (JP, A) JP-A-9-159582 (JP, A) JP-B 2-54514 (JP , B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01M 19/00 G01N 33/20

Claims (5)

(57) [Claims] 1. The hardness of an evaluation portion that is subject to creep damage due to temperature and the passage of time in a measurement portion of a high-temperature member containing a metal material is measured a plurality of times at time intervals, and each of the measured values of the evaluation portion is measured. Based on the difference, the hardness decrease amount due to creep damage of the evaluation part after a certain time corresponding to the time interval is calculated, and the creep for the time interval is calculated from the calculated hardness decrease amount and the time interval. The damage accumulation amount is calculated, and the creep damage rate of the evaluation unit is calculated from the time ratio between the time corresponding to the end of the time interval and the time interval and the calculated creep damage accumulation amount. A method for predicting the life of a high temperature member, which predicts the life of the high temperature member. 2. The hardness of an evaluation portion of a measurement site of a high temperature member containing a metal material, which is subject to creep damage due to temperature and the passage of time, is measured a plurality of times at time intervals, and each of the measured values of the evaluation portion is measured. Calculate the hardness decrease amount of the evaluation part after a certain time corresponding to the time interval from the difference, and calculate the hardness of the no-load heating material a plurality of times corresponding to the time interval, the no-load heating Calculate the hardness decrease amount of the unloaded heating material after a lapse of a certain time corresponding to the time interval from the difference between the calculated values for the material, the calculated hardness decrease amount of the evaluation unit and the calculated Calculate the amount of creep damage accumulated for the time interval from the amount of decrease in hardness due to creep damage showing the difference between the hardness decrease amount of the load heating material and the time interval, and the time corresponding to the end of the time interval and the Time ratio with time interval Calculate the creep damage rate of the evaluation unit from the rate and the calculated creep damage accumulation amount,
A method for predicting the life of a high temperature member, which predicts the life of the high temperature member according to the calculation result. 3. The residual life as a life for the high temperature member is predicted from the calculated value of the creep damage rate of the evaluation unit and the time corresponding to the end of the time interval. Life Prediction Method for High Temperature Parts. 4. The hardness of the reference portion is measured a plurality of times corresponding to the time interval, using a portion of the measurement portion of the high temperature member that is not damaged by creep due to temperature and time as a reference portion. The life prediction method for a high temperature member according to claim 1, wherein the hardness decrease amount due to the creep damage is corrected based on the difference between the measured values. 5. The hardness of an evaluation portion that is subject to creep damage due to temperature and the passage of time among a measurement portion of a high temperature member containing a metal material is measured a plurality of times at time intervals, and the hardness of each measurement value of the evaluation portion is measured. A high temperature member that calculates the hardness decrease amount of the evaluation part after a certain time corresponding to the time interval from the difference, and estimates the initial hardness of the evaluation part from the calculated value and the creep damage rate of the evaluation part. Life prediction method.