JPH05172785A - Degradation measuring device - Google Patents

Abstract

PURPOSE:To detect a creep damage with a non-destractive method even at a part difficult to measure and evaluate the result. CONSTITUTION:By using a inspection head 3 easy to insert in a center hole 2 of a turbine rotor 1 which a stress is acting on at high temperature, and to fix at a specified position, measurement is performed at a low temperature and high stress part in the center hole 2 of the turbine rotor 1 and the result in input to a measurement controller 6. The load stress obtained with a calibration curve between the measured value and the stress and the measured value obtained at the object measurement part are applied to a calibration curve (relation between the creep damage and measurement value) obtained experimentally in advance, degradation is measured and creep damage is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for long-term use in a high temperature environment, and a deterioration measuring apparatus for measuring the degree of material deterioration and damage of members.

[0002]

2. Description of the Related Art It is known that equipment and members such as steam turbines that are used in a high temperature state are exposed to a high temperature environment for a long period of time under the stress of heat, so that they are deteriorated and damaged by creep. Has been. During the creep process, which progresses to deterioration and damage, creep voids are generated, grow, coalesce, and further grow into cracks, and eventually break. Therefore, deterioration of material due to creep,
It is extremely important in detecting the degree of damage and determining the degree of damage.

Conventionally, there have been various methods for measuring creep damage, such as creep void measurement and hardness measurement by observing the structure. However, all of these measurement methods have limited application measurement sites, and particularly turbines. It has been difficult to apply to equipment members having circular holes such as the center hole of the rotor.

Also, a method of utilizing a change in magnetic properties of a material as a means of nondestructive measurement has been considered for a long time. As an example, there is a method to measure the intensity of the Barkhausen signal generated in the magnetization process when a magnetic field is applied to the measurement target.However, in this method, the stress acting on the ferromagnetic material and the residual stress during manufacturing are measured. Is associated with the measured value (Japanese Patent Laid-Open No. 59-112257), and at present, there is no evaluation example of creep damage.

[0005]

As described above, according to the conventional method of measuring the creep damage, the creep damage occurs in the equipment or member exposed for a long time in the high temperature environment, for example, the structure having the circular hole such as the central hole of the turbine rotor. When measuring and evaluating the degree of deterioration of creep damage, it was difficult to actually measure the degree of deterioration damage because of the restrictions on the shape, size, and configuration of the creep detector.

The present invention has been made in view of the above points, and provides a deterioration measuring apparatus capable of detecting and evaluating creep damage by a nondestructive method even for a portion having a shape that is difficult to measure. The purpose is to

[0007]

In order to achieve the above object, the present invention provides a magnetizer for applying an alternating magnetic field to a material to be tested which is made of a ferromagnetic material and is used under high temperature and high stress. An inspection head having a detector for detecting a signal periodically generated in the magnetization process of the material to be inspected; a supporting means for supporting the inspection head and moving the measurement head to the measurement site of the material to be inspected; Current supply means for supplying an alternating current to the magnetizer of the inspection head to generate a predetermined alternating magnetic field at the measurement site of the ferromagnetic material, and a detection signal detected by the detector of the inspection head are input. Signal processing means for analyzing and processing the detection signal to measure various parameters,
Stress is measured using various measurement parameters measured by this signal processing means, and an operation means for creating a calibration curve showing a calibration curve showing the relationship between the stress value and the measured value and the measurement parameter and the creep damage degree, and in advance. Memory that stores a calibration curve created based on the measured values and stress values of various parameters measured for known test materials and the measured values of various parameters and creep damage, along with data such as material, temperature, and stress. Means and a calibration curve corresponding to the material, temperature, stress, etc. of the material to be tested are fetched from the storage means and compared and calculated with the calibration curve created by the computing means to measure the creep damage degree of the material to be tested. And deterioration determination means for determining.

[0008]

In the deterioration measuring device having such a structure, the creep damage degree of the test material is measured by the following functions. First, the inspection head is moved to the measurement site of the material to be inspected by the supporting means and installed at that site. When an AC magnetic field is applied to the test material by the magnetizer of the inspection head in this state,
The detector detects the Barkhausen signal generated by the load reverse and discontinuous movement of the domain wall. Ferromagnetic materials are generally called magnetic domains having different spontaneous magnetization vectors. The magnetic domain wall moves irreversibly and discontinuously in the process of domain growth (magnetization process) in response to the application of an external magnetic field, and the Barkhausen signal is generated accordingly, but the domain wall moves due to the difference in the structure of the material or the change in the structure. Is output as a signal having different amplitude values and different pulse numbers.

Such a signal is input from the detector of the inspection head to the signal processing means, where the detected signal is analyzed and various parameters are measured and given to the deterioration determining means. The measurement of the degree of creep damage of the material to be inspected by the deterioration determining means is performed by fetching the data stored in advance in the storage means.

The data stored in this storage means includes the measurement parameters (eg, peak voltage value of signal waveform, pulse number, etc.) and deterioration degree by the Barkhausen method with respect to known test materials that have undergone different creep damages in advance. The calibration curve is obtained from the relationship of, and this is used as data. In this case, since it is known that the measured values of the Barkhausen method using the creep test materials having different stress conditions show the values depending on the stress, it is possible to create the calibration curve for each load stress value.

Next, in order to measure the creep damage degree of the test material, first, measurement is performed by the Barkhausen method at a portion to which the same load stress as that of the test material is applied in a low temperature environment, and the measurement parameter is analyzed. The load stress is obtained by applying the measured value obtained by the processing to the stress and the calibration curve of the measured value. Also, the measured values obtained by the measurement of Barkhausen method for the unknown measurement site of creep damage are applied to the calibration curve obtained for the test material, and the calibration curve based on the load stress obtained under the low temperature environment at that time is applied. The creep damage degree is measured by collation and comparison calculation.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a structural example of a deterioration measuring apparatus according to the present invention. In FIG. 1, 3 is an inspection head that is inserted into a central hole in the axial direction of the turbine rotor 1. This inspection head 3 has a magnetizer 31 formed by winding a coil 31b around an iron core 31a, and the inside thereof. Core 32a
A detector 32 formed by winding a detection coil 32b is disposed on the outside of the magnetizer 31. The magnetizer 31 and the detector 32 are covered with magnetic shield boxes 33 and 34, respectively, so that disturbance noise is cut off. ing. Here, the magnetizer 31 applies an alternating magnetic field to the inner surface of the central hole of the turbine rotor 1 in the axial direction, and the detector 32 is guided by the detection coil 32 when the alternating magnetic field is applied to the inner surface of the central hole. The electromagnetic wave is detected.

On the other hand, 6 is a measurement control unit, and this measurement control unit 6 is a microprocessor (CPU) 7 that plays a central role in control.
And a signal generator 8 that generates a signal having a predetermined oscillation waveform (for example, triangular wave) and frequency according to a control command from the CPU 7 as a power supply system of the magnetizer 31, and the output signal of the signal generator 8 is converted into a constant current to magnetize Coil 31 of container 31
b is provided with a constant current source 9 which is provided through a signal cable 51. Further, the detection processing system includes a detection sensor 3
Filter 1 for extracting a high-frequency component as a signal (Barkhausen signal) from the electromagnetic wave induced in the detection coil 32b of
0, an amplifier 11 that amplifies the signal extracted from the filter 10, a CRT 12 and a frequency analyzer 13 for observing the detection signal waveform amplified by the amplifier 11.
And a signal processing circuit 14 for taking in the signal amplified by the amplifier 11 according to a command from the CPU 7. The signal processing circuit 14 measures the peak amplitude value, the number of pulses above the threshold level, the pulse amplitude distribution, the envelope shape of the signal waveform, and the peak pulse generation time of the signal (rise time). Various kinds of signal processing such as measurement are performed, and these measured values are treated as measurement parameters of the Barkhausen method.

Further, the result of signal processing by the signal processing circuit 14 is stored in the storage device 15 as a measurement result and is also guided to the deterioration degree evaluation calculation circuit 16. This deterioration degree evaluation calculation circuit 16 has a database of measurement results of various test materials, and correction curves for stress and measurement values, creep damage degree and measurement values, etc., together with data such as temperature, stress, and material, etc.
The measurement result of the test material and these calibration curves stored in the internal memory are subjected to a comparative calculation process to determine the degree of creep damage of the test material. Further, the deterioration degree determination result of the deterioration degree evaluation calculation circuit 16 and the measurement result of the measurement parameter stored in the storage device 15 can be selectively displayed on the display unit 17. All of these series of measurement and signal processing are managed by commands from the CPU 7. Next, the operation of the deterioration measuring device configured as described above will be described.

Now, as shown in FIG. 2, the inspection head 3 is inserted into the axial center hole 2 of the turbine rotor 1 via a scanning rod 4, and the axial center and the circumferential direction of the center hole 2 are arbitrarily set. It is assumed to be set to the position.

In such a state, the magnetizer 3 is fed from the constant current source 9.
When an alternating current having a predetermined frequency is applied to the first coil 31b, the load current value changes from negative to positive as shown in FIG.
The measurement portions of are also magnetized in the same direction as the magnetizing current direction. That is, a magnetizing circuit that passes through the magnetizer 31 and the measurement site of the turbine rotor 1 is formed, and the direction of the magnetic flux, that is, the direction of magnetization, changes alternately as shown by arrow S in the figure.
At this time, at the measurement site, the domain wall in the material moves irreversibly and discontinuously under the influence of the magnetic field, and the signal generated by this movement is detected by the detector 32 as an electrical signal waveform.

FIG. 4 (a) is a schematic diagram of the generation state of the magnetizing current and the detection signal, and the detection signal is periodically generated with the change of the magnetizing current. This signal waveform is input to the signal processing circuit 14 through the amplifier 11, where the following analysis processing is performed. That is, as shown in FIG. 4A, the peak voltage V _p having the maximum amplitude of each signal and the magnetic field H = 0.
And the times t ₁ and t ₂ (rise time) between the rising position of the signal and the peak pulse generation position of the signal, the envelope shape of the signal waveform shown in FIG. 7B, and the single signal shown in FIG. The number of pulses above the threshold level in the waveform C ₁ , C ₂ ,
...... C _n , the pulse amplitude distribution of the signal waveform shown in FIG. 7D, etc. are measured and analyzed as the measurement parameters of the Barkhausen method, and this signal waveform corresponds to the structural change in the material. It has been experimentally confirmed to change.

Therefore, a plurality of test materials to which different known stresses are applied in advance are measured by the above-mentioned Barkhausen method, signal processing is performed to measure the measurement parameters, and the measurement parameters and stress values are Create a calibration curve. Next, using a test material with a known degree of creep damage,
The deterioration measurement similar to the above is performed, and the calibration curves of various parameters and the deterioration degree are created as described above.

The calibration curves of the respective measurement parameters and stress values and the calibration curves of the deterioration degrees of the various parameters thus created are stored in the memory in the deterioration degree evaluation arithmetic circuit 16 and stored in a database.

FIG. 5 shows a deterioration degree evaluation flowchart using the apparatus of the above-mentioned embodiment, and its operation will be described below according to this flow. First, the measurement conditions for the measurement site are set. Next, the measurement site for evaluating the degree of creep damage is measured in a low temperature environment at the low temperature and high stress site where the same stress as the site to be evaluated is loaded in the low temperature environment, and the measurement values of each measurement parameter are as described above. Then, the applied stress is measured by applying it to the calibration curve previously obtained from the relationship between the stress and the measured value. In the figure, the peak voltage value is shown as a measured value as an example of the measured parameter, but similar processing is performed for other parameters. Here, the load stress σi obtained by each measurement parameter is subjected to statistical processing or the like to perform a comprehensive evaluation of the load stress value.

Next, following the above measurement, the same measurement as described above is performed for the high temperature and high stress region which is the measurement target region, and the measured value is applied to the calibration curve (A) which has been prepared in advance. As shown in the figure, it is not possible to apply the peak voltage value to the calibration curve (A) because it is recognized that the stress is different and the load stress is unknown. Therefore, using two types of calibration curves that are stored in a database in advance and using the measured value found in relation to the load stress as the reference value (Vref), the measured value (Vi) found for the creep damaged material can be standardized. A simple curve such as the deterioration evaluation curve in the figure is obtained.

Therefore, the creep damage degree φi can be obtained by fitting it to the deterioration evaluation curve using the measured value obtained at the measurement target portion and the load stress σi obtained at the low temperature high stress portion.

Such an operation is performed for other measurement parameters (for example, the pulse number and rise time), and the load stress σi obtained in the same manner is comprehensively evaluated in consideration of statistical processing and the like, whereby creep damage is obtained. You can ask for degrees.

Therefore, by incorporating the program according to the flow chart shown in FIG. 5 into the apparatus of the above embodiment and performing a series of measurement, analysis and evaluation, the creep damage degree of the target measurement site can be easily detected and the measurement site can be easily measured. It is possible to measure the stress of.

As described above, in this embodiment, the inspection head which is easy to put in and out of the central hole 2 of the turbine rotor 1 at high temperature and under stress and fixedly installed at a predetermined position is used. It measures creep damage and evaluates the degree of deterioration. That is, the measurement value measured at the low temperature and high stress portion of the center hole 2 of the turbine rotor 1, the load stress obtained from the calibration curve of this measurement value and the stress value, and the measurement value obtained at the target measurement portion are obtained in advance by experiments. By applying the calibration curve (relationship between creep damage and measured value) to measure the degree of deterioration, it is possible to detect creep damage.

Therefore, it is possible to detect and evaluate the creep damage by the nondestructive method even for a portion having a shape that is difficult to measure. Further, it becomes possible to measure the load stress in the low temperature and high stress region as well, and it becomes possible to measure with high accuracy like the center hole 2 of the turbine rotor 1 and to measure the center hole 2 of the turbine rotor 1 with higher accuracy. Therefore, it has a great effect on the soundness evaluation and the life evaluation of the device members, and thus the proper inspection can be performed.

In the above embodiment, the case where the degree of deterioration of a circular structure such as the central hole of the turbine rotor 1 is measured has been described, but the present invention is not limited to this and the inspection head If the shape is transformed into an appropriate shape and applied, the degree of deterioration and evaluation of the material to be inspected can be performed in the same manner as described above even for a structure having various shapes such as a flat surface and a curved surface.

[0029]

As described above, according to the present invention, it is possible to provide a deterioration measuring device capable of detecting and evaluating creep damage by a nondestructive method even for a portion having a shape which is difficult to measure.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of a deterioration measuring device according to the present invention.

FIG. 2 is a diagram showing a state in which an inspection head is inserted into a center hole of a turbine rotor in the embodiment.

FIG. 3 is an operation explanatory view when an inspection head detects an electromagnetic wave in the embodiment.

FIG. 4 is an explanatory diagram of each measurement parameter of a detection signal according to the same embodiment.

FIG. 5 is a view showing a flowchart for performing deterioration evaluation of the same embodiment.

[Explanation of symbols]

1 ... Turbine rotor, 2 ... Center hole, 3 ... Inspection head, 4 ... Operation rod, 51 ... Cable, 6 ... Measurement controller, 7 ... Microprocessor, 8 ... Signal generator, 9 ... constant current source, 10 ... filter, 11 ... amplifier, 12 ... CRT, 13 ... frequency analyzer, 14 ...
Signal processing circuit, 15 ... Degradation degree evaluation arithmetic circuit, 17 ...
display.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Furumura 2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Keihin Plant (72) Inventor Satoshi Nagai 2-cue, Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Address inside Toshiba Keihin office

Claims (1)

[Claims] 1. A magnetizer for applying an alternating magnetic field to a material to be tested made of a ferromagnetic material used under high temperature and high stress, and a signal generated periodically during the magnetization process of the material to be tested by the magnetizer is detected. An inspection head having a detector for supporting the inspection head, supporting means for supporting the inspection head and moving the measurement head to a measurement site of the material to be installed, and supplying an alternating current to the magnetizer of the inspection head to increase the strength. A current supply means for generating a predetermined AC magnetic field at a measurement site of a magnetic material and a detection signal detected by the detector of the inspection head are input, and signal processing means for analyzing and processing the detection signal to measure various parameters. And a calculation means for measuring stress using various measurement parameters measured by the signal processing means, and creating a calibration curve showing the relationship between the stress value and the measured value and the measurement parameter and the creep damage degree, and Therefore, a calibration curve created based on the measured values and stress values of various parameters measured on known test materials and the measured values of various parameters and creep damage was stored together with data such as material, temperature, and stress. The storage device and the calibration curve corresponding to the material, temperature, stress, etc. of the test material are fetched from the storage means and are compared and calculated with the calibration curve created by the calculation means to determine the creep damage degree of the test material. A deterioration measuring device, comprising: deterioration determining means for measuring and judging.