JPH02262026A - Method and apparatus for nondestructive inspection - Google Patents

Abstract

PURPOSE:To measure internal stress and to make it possible to measure mechanical property highly accurately without destruction by providing a fluxmeter which measures the intrinsic magnetic characteristics of a body under test and the change in characteristics in a stress measuring means. CONSTITUTION:When a measuring probe 22 is brought into contact with a body under test 23, a magnetic circuit 24 is formed. When a current is made to flow through a coil 25, magnetic flux is generated in the magnetic circuit 24. When internal stress is present in the body under test, permeability is changed in response to the magnitude of the internal stress, and the magnitude of the magnetic flux is changed. The difference in magnetic fluxes is obtained by measuring the unbalanced current in a specified bridge circuit. Thus, the internal stress is obtained. Meanwhile, an exciting coil 28 and a fluxmeter 21 provided with a pickup coil 29 are provided in the measuring probe 22. Magnetomotive forces having the different values are sequentially imparted. A magnetic hysteresis curve in an internal-stress measuring region is obtained. The magnetic characteristics are obtained from the curve. The mechanical property can be obtained based on the characteristics.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a non-destructive testing method and apparatus for measuring internal stress existing on the surface of a metal material, and in particular to a non-destructive testing method and apparatus for measuring internal stress existing on the surface of a metal material. The present invention relates to a non-destructive testing method and device capable of measuring mechanical properties without any problems.

[Conventional technology]

Boiler piping and turbine rotors used in high-temperature environments gradually change their mechanical properties, such as the tensile strength of the metal materials that make up them, depending on the usage conditions, so they cannot be used for long periods of time. A material test will be conducted on the product. This material test cannot be performed by collecting test pieces, as is normally done, because the test objects are actual machine parts such as piping and rotors that are in operation. For these reasons, generally only hardness measurements that can be performed with the actual machine parts installed without taking test pieces are carried out as material tests, and tensile strength etc. can be estimated from the obtained hardness data. is being carried out. A hardness measuring device described in Japanese Patent Publication No. 57-84336 has been proposed as a hardness measuring device for the inner wall of a pipe or the inner surface of a rotor center hole. The hardness of a material is a measure of the resistance it exhibits when it is deformed by another object, and various testing methods and testing machines have been devised to quantitatively measure this. (For example, Mechanical Research Vol. 37,
No. 10 (1985), P25) On the other hand, JP-A-62-2
Japanese Patent No. 40851 describes a material testing device equipped with means for applying plastic deformation to a test object with an indenter having a pressurizer or the like and detecting a change in magnetic permeability of the test object using a double coil.

This measures the initial magnetic permeability μ of the specimen, applies plastic deformation to the specimen, then measures the initial magnetic permeability μ2 of the plastically deformed portion, and then calculates the initial magnetic permeability μm and μ2 of the specimen. This is a material testing method that determines the mechanical properties of a specimen. In this method, the initial permeability of the object is influenced by internal stress due to magnetostrictive effects.

Regarding stress measurement devices using magnetostrictive effects, see Nondestructive Testing Vol. 37, No. 9 (1988) PP730-736.
It is described in.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into consideration the influence of plastic deformation that the test object undergoes during measurement, and is unable to non-destructively (without plastic deformation) inspect the material. Therefore, it is not suitable for measuring the mechanical properties of objects that require non-destructive testing, such as actual equipment in nuclear power plants.

In addition, in the technology described in JP-A No. 62-240851, the initial magnetic permeability is affected by the residual stress existing inside the actual machine member, so unless the influence of the residual stress on the initial magnetic permeability can be measured, the initial magnetic permeability cannot be measured. It was not possible to measure the mechanical properties of the actual components based on changes in magnetic permeability.

An object of the present invention is to non-destructively measure the internal stress localized in an object to be examined, and also to measure changes in the mechanical properties of the object non-destructively and with high precision.

[Means to solve the problem]

The above problem is solved by a non-destructive inspection apparatus equipped with a stress measuring means that uses magnetism to detect the internal stress of a test object, and a magnetometer that measures magnetic properties specific to the test object and changes thereof. This can be achieved by having the following.

a stress measuring means that comes into contact with the subject and detects the internal stress of the subject; and a stress measuring means that is provided concentrically with the stress measuring means and that comes into contact with the subject and measures magnetic properties specific to the subject and changes thereof. It is also possible to use a non-destructive testing device equipped with a magnetometer.

Further, a stress measuring means that contacts the subject and detects the internal stress of the subject, and a stress measuring means that is provided between the stress measuring means and the subject and that contacts the subject and detects the internal stress of the subject, and a magnetic property unique to the subject. and a magnetometer that measures the change thereof.

Further, a magnetometer is provided between the magnetometer and the test object to contact the test object to measure magnetic properties specific to the test object and changes thereof, and a magnetometer is installed between the magnetometer and the test object to contact the test object and measure the internal magnetic properties of the test object. A non-destructive testing device may also be provided, including stress measuring means for detecting stress.

Further, the stress measuring means includes a measurement probe that has a core made of a high magnetic permeability material or a soft magnetic material and has an excitation coil and contacts the subject, a compensation probe that has the same specifications as the measurement probe, and a compensation probe that has the same specifications as the measurement probe. a bridge circuit including a measurement probe and a compensation probe; unbalanced current measuring means for measuring an unbalanced current value of the bridge circuit; The non-destructive testing apparatus according to any one of claims 2 to 4, further comprising: calculation means for calculating internal stress.

Further, the non-destructive testing apparatus according to claim 5, wherein the probe is formed in a U-shape, and both ends of the U-shape are magnetic poles that contact the subject.

The computer also includes a computer that graphs the internal stress value, the coercive force, and the residual magnetic flux density of the object outputted from the calculation means, with the measurement position of the object as one coordinate axis, and a computer that is connected to the computer and displays the graph. The non-destructive inspection apparatus according to claim 5 or 6 may be provided with a display means.

Claim 6 further characterized in that a magnetometer is disposed at the center between the magnetic poles.
It is also possible to use the non-destructive testing device described in .

9. The non-destructive testing according to claims 5, 6 and 8, wherein the contact surface of the measurement probe with the subject is rotatable within the contact surface about a center line of the measurement probe perpendicular to the contact surface. It may also be used as a device.

The non-destructive inspection apparatus according to any one of claims 1 to 9, wherein the test object is an equipment material or an actual machine member of any one of a chemical plant, a thermal power plant, and a nuclear power plant.

The present invention also includes a stress measuring means that contacts the subject and detects the internal stress of the subject, and a magnetizing coil and a detection coil that are provided concentrically with the stress measuring means and measure eddy currents specific to the subject. It is also possible to use a non-destructive inspection device equipped with the following.

Further, a stress measuring means that contacts the subject and detects the internal stress of the subject; an excitation coil and a detection coil for measuring noise;
The non-destructive testing device may include an oscillator that supplies a low frequency voltage to the excitation coil.

Further, the magnetometer includes an excitation means for applying a magnetomotive force to the subject;
The non-destructive testing apparatus according to any one of claims 1 to 1o, further comprising a Hall element that detects magnetic flux induced from the subject by a given magnetomotive force.

Further, the magnetometer includes a superconducting coil that applies magnetomotive force to the subject, and a superconducting pickup coil that detects magnetic flux induced from the subject by the applied magnetomotive force. It may also be used as a non-destructive testing device.

In addition, the above problem is to sequentially apply different values of magnetomotive force to the test object, detect magnetic lines of force induced from the test object by the magnetomotive force, obtain a magnetic hysteresis curve, and calculate the magnetic hysteresis curve. This can also be achieved by a non-destructive testing method that determines the magnetic properties of the object based on the magnetic properties and determines the mechanical properties of the object based on the obtained magnetic properties.

Furthermore, the influence of internal stress on the magnetic properties of the specimen is converted into data in advance, and a closed magnetic circuit passing through the specimen and the measurement probe, and a magnetic circuit passing through the reference specimen and the compensation probe are formed. There is a procedure for detecting the internal stress of a test object based on the difference in magnetic resistance of the circuit, and a magnetic hysteresis method by sequentially applying different values of magnetomotive force to the test object and detecting the lines of magnetic force induced from the test object by the magnetomotive force. a step of obtaining a hysteresis curve and obtaining the magnetic properties of the object based on the magnetic hysteresis curve; correcting the magnetic properties using the internal stress obtained in the previous step; and correcting the magnetic properties based on the corrected magnetic properties. The method may also be a non-destructive testing method for determining the mechanical properties of the object.

[Effect]

When a measurement probe is applied to the surface of a subject, a closed magnetic circuit is formed. When a current is passed through a coil wound around the measurement probe, a magnetic flux is generated in the magnetic circuit. When internal stress exists in the object.

Due to the magnetostrictive phenomenon, the magnetic permeability of the object changes in accordance with the magnitude of the internal stress, and the magnitude of the magnetic flux changes accordingly. There is a difference in the magnitude of the magnetic flux generated in the compensation probe that contacts a reference specimen with no internal stress to form a magnetic circuit and the magnitude of the magnetic flux generated in the measurement probe, and the magnetic flux generated in the measurement probe is different from that in the measurement probe. Unbalanced currents occur in the bridge circuit formed. Since this unbalanced current corresponds to the magnitude of the internal stress of the subject, the internal stress can be obtained by measuring the unbalanced current.

A magnetometer equipped with an excitation coil and a pickup coil is installed at the center between the magnetic poles of the measurement probe, and magnetomotive force of different values is sequentially applied to the subject, and the magnetic hysteresis curve ( BH curve) is determined. The magnetic properties of the object obtained from this magnetic hysteresis curve are corrected for the magnetostrictive effect due to the previously measured internal stress, thereby obtaining magnetic properties that exclude the effects of internal stress. Since this magnetic property is correlated with the mechanical property of the subject, the mechanical property of the subject can be obtained based on the corrected magnetic property.

Methods for obtaining the magnetic properties of the object include a method using eddy current and a method using Barkhausen noise, and similar effects can be obtained.

The measurement probe, which is the stress measurement means, and the magnetometer (eddy current detection coil, Barkhausen noise detection coil), which measures the magnetic properties, are arranged concentrically, so it is easy to detect the internal stress detection position and the magnetic properties. The positions match and the positional accuracy is high.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a state in which a turbine rotor 1, which is an object to be inspected, is inspected by a nondestructive inspection apparatus that is an embodiment of the present invention. The nondestructive testing device shown in the figure includes a stress measuring device 3 attached to a center hole 2 provided in a turbine rotor 1, and a stress measuring device 3 connected to the stress measuring device 3 to measure the stress on the inner circumferential surface of the center hole 2. An operating rod 5 to be moved, and a feeding device 4 to move the operating rod 5 in the axial direction and rotate it around the axis.
and.

It includes a cable 6 connected to the stress measuring device 3, and a data conversion device 7 and an arithmetic controller 8 connected to the other end of the cable.

FIG. 2 shows an example in which the non-destructive inspection apparatus according to the present invention is applied to the inspection of a nuclear reactor pressure vessel. The non-destructive testing device shown in the figure includes a stress measuring device 3 mounted on the inner wall of a reactor pressure vessel 11, a crane 17 supporting the stress measuring device 3, and a crane 17 connected to the stress measuring device 3. and a controller 18. The specimen may be various thick-walled containers used in chemical plants.

FIG. 3 is a sectional view of a main part of the stress measuring device shown in FIGS. 1 and 2. FIG. The stress measurement device shown in the figure includes a highly sensitive magnetometer 21 that measures the magnetic properties of a subject 23, and a
1, provided so as to be able to contact the subject 23.
A U-shaped probe 22 made of a high magnetic permeability material, a coil 25 wound around the probe 22, and the magnetometer 21.
A pickup coil 26 is provided on a surface facing the subject 23 and connected to the magnetometer, and an excitation coil 28 is provided attached to the magnetometer.

The magnetometer 21 is placed at the center of the U-shape of the probe 22 . The probe 22 and the coil 25 wound around the probe 22 constitute a measurement probe that measures the internal stress of the test object by bringing its U-shaped end into contact with the test object,
Something with a similar configuration.

It is provided as a compensation probe. The measurement probe and the compensation probe are connected to a constant voltage circuit 46° slideac 47. Galvanometer for bridge current measurement 45, complaint fIij
! Together with the galvanometer 44 for current measurement, a bridge circuit is formed to constitute stress needle 1 constant means.

To perform measurement using the stress measuring device with the above configuration, first,
The probe 22 connects its U-shaped end 22A to the subject 23.
The compensating probe is placed with its end in contact with the surface of a reference specimen having no internal stress. The subject 23 and the probe 22 form a closed magnetic circuit 24, and similarly, the compensation probe and the reference sample also form a closed magnetic circuit. Current is passed through the coil 25 and the coil of the compensation probe, and magnetic flux is generated in the magnetic circuits of both. However, if internal stress 27 exists within the stress measurement region 26 of the subject 23, the internal stress will be reduced due to the magnetostrictive phenomenon. According to the size, the stress measurement area 2
6 changes in magnetic permeability.

Therefore, a difference occurs between the magnetic reluctance of the magnetic circuit 24 and the magnetic reluctance of the magnetic circuit of the compensation probe that is in contact with the reference specimen free of internal stress. The difference in magnetic flux density based on this difference in magnetic resistance is converted into an electric signal by a measurement circuit using a bridge circuit shown in Figure 5, and based on the relationship between internal stress and magnetic permeability that has been converted into data in advance, Stress measurement area 26
The internal stress within is calculated and output. By moving the probe 22 along the surface of the subject 23 and measuring stress at a plurality of locations, the stress distribution of the subject 23 can be obtained.

Next, the excitation coil 28 is energized to apply a magnetomotive force to the stress measurement region 26 of the subject 23 . The test object 23 in the stress measurement area 26 generates magnetic lines of force 30 based on the magnetomotive force, but the magnetic properties 2 of the test object 23, such as initial magnetic susceptibility and maximum magnetic susceptibility, are affected by the magnetostrictive effect due to residual stress, and the residual magnetic flux Density and coercive force are not only affected by the magnetostrictive effect, but also
It changes depending on precipitates and foreign phases inside the specimen. The mechanical properties of the material to be tested change depending on the precipitates and different phases, so the strength of the magnetic lines of force generated based on a given magnetomotive force changes with changes in the internal stress and mechanical properties of the test piece. Change. The magnetic lines of force 30 are taken in by the pickup coil 29, their values are measured by the magnetometer 21, and based on the values, values indicating the magnetic properties of the subject are determined. The obtained value was corrected for the influence of the magnetostrictive effect due to residual stress (internal stress), which had been converted into data based on the previously measured internal stress value, and the influence of internal stress was excluded. , the amount of change in magnetic properties can be obtained. Since this magnetic property is related to the mechanical property of the subject, by converting the relationship between the magnetic property and mechanical property into data in advance, the subject 23 can be identified based on the measured magnetic property. The mechanical properties of are determined.

FIG. 4 shows another embodiment of the stress measuring device according to the present invention. In the embodiment shown in the figure, a magnetometer 32 having a pickup coil 31 and an excitation coil 24 for measuring the magnetic properties of an actual component is placed outside a probe 33. A coil 36 that generates magnetic flux in the probe 33 is wound around the legs of the U-shaped probe 33, and has a center line in the center of the probe 33 that is perpendicular to the surface of the probe 33 that contacts the subject. A center hole 34 is provided. The magnetometer 32 is provided concentrically with the center hole 34 with a pickup coil 31 located outside the center hole 34, and the magnetic flux meter 32 is arranged concentrically with the center hole 34, and directs the magnetic field lines 35 emitted by the stress measurement area 26 to the outside of the center hole 34. Since the pickup coil 31 can take in the probe 33, the probe 33 can be made smaller.

In this embodiment, magnetic lines of force 35 from the stress measurement region 26 of the subject 21 are introduced into the pickup coil 31 through the center hole 34 .

Further, the probe 33 is formed to be rotatable around the center line of the center hole 34, and while rotating around the center line, the stress can be measured at multiple positions and the values compared. The direction of stress action within the stress measurement region 26 is also detected.

In addition, in the embodiment shown in FIGS. 3 and 4, the stress measurement area 2
Although a pickup coil is provided to detect lines of magnetic force from 6, a Hall element may be used instead.

FIG. 5 shows an example of a circuit configuration for stress measurement. The circuit shown in the figure includes a measurement probe (magnetostrictive tube) 41, a compensation probe 42, a rectification circuit 48 using diodes connected to the measurement probe 41 and the compensation probe 42, and a measurement circuit connected to the rectification circuit 48. 43, a galvanometer 44 for measuring unbalanced current, and a resistor γ0 connected to the rectifier circuit 48. γ2. and a variable resistor γ1, a galvanometer 45 for bridge current measurement connected to the measurement probe 41 and the compensation probe 42, and a constant voltage connected to the galvanometer 45 and the variable resistor γ via a slide duck 47. device 46, the constant voltage device 46 has a 50Hz
, 100V power is supplied. The measurement probe 41 referred to here is the probe 22 (coil 2
(including 5).

This corresponds to the probe 33 (including the coil 36) shown in FIG. 4, and is also called a stress tester.

The measurement probe 41 forms a bridge circuit together with the compensation probe 42, and an unbalanced current based on the difference in magnetism detected by the compensation probe and the measurement probe, that is, the difference in inherent stress, is generated in this bridge circuit. This is measured by the unbalanced current measuring galvanometer 44, and the difference in stress is determined.

The magnetic flux distribution generated by the stress tester 52, whose surface 52A facing the subject is rectangular as a whole, has a shape as shown in FIG. FIG. 6 shows the magnetic flux distribution generated on the surface of the test object during stress measurement, when the distance between the magnetic poles of the stress tester 52 used is 5 cn. In the figure, the magnetic flux density at a position 5G away from the midpoint of the stress tester magnetic pole (the origin of the figure) is 115
It has decreased to ~1/6. FIG. 6 shows a case where the object under test is stress-free, but even when it is under stress, the magnetic field is distorted, but the ratio of strength and weakness depending on the location of the magnetic flux distribution does not differ greatly from the case without stress. Therefore, the stress measured by the stress tester 52 is within a radius of 50 (distance between magnetic poles) centered on the origin in FIG. It represents the average stress of the subject within the circle. Thus according to the invention.

The stress measurement range can be limited.

FIG. 7 is an example of the magnetic characteristics of the turbine rotor inner wall measured by the magnetometer 21. The excitation coil shown in FIG. 3 applies a magnetomotive force H to the inner wall of the turbine rotor, and the pickup coil measures the magnetic flux density B. When the value of the applied magnetomotive force is sequentially changed, the measured value passes through an initial magnetization curve 61 and draws a magnetic hysteresis loop 62.

If residual stress exists on the inner wall of the rotor, the magnetic field is distorted, and due to the so-called magnetostriction effect, the initial magnetic susceptibility 63 and the maximum magnetic susceptibility 64 change compared to the case where there is no stress. In addition, residual magnetic flux density 65. Coercive force 66 is also affected by magnetostrictive effects.

In Figure 8, the stress and magnetic characteristics were determined using the stress measuring device 3 at multiple axial positions on the inner wall of the center hole of the turbine rotor 1, and the horizontal axis represents the axial measurement positions and the vertical axis represents the output value. , stress distribution 71. 7 is a diagram showing a coercive force distribution 72 and a residual magnetic flux density distribution 73. FIG. If you use an unused material of the same material as the turbine rotor to determine the amount of change in magnetic property values due to changes in internal stress, you can calculate the coercive force that has changed due to changes in the material inside the rotor, excluding the magnetostrictive effect. distribution and residual magnetic flux density distribution.

FIG. 9 shows the stress distribution 81 localized on the inner wall of the reactor pressure vessel 11, which was obtained using the device shown in FIG. 2 by attaching an unloaded sample to the compensation probe. The axial position of the reactor pressure vessel 11 is plotted with measured values on the vertical axis. In addition, the coercive force distribution 83 and the residual magnetic flux density distribution 84 are determined by excitation and measurement at a plurality of locations using a magnetometer provided in the stress measuring device 3. Furthermore, as shown in FIG. 10, when the reactor is operating, the reactor pressure vessel lid 91 is attached to the upper part of the reactor pressure vessel 11, so the axial stress before and after the reactor pressure vessel lid 91 is installed is In the vector sum of the increments of τe, radial stress τ, and circumferential stress, if the component in the measurement direction of the stress tester is added to the stress distribution 81 in FIG. 9, the stress distribution correction value 85 is found, It is also possible to estimate the stress distribution at the start of reactor operation (low temperature).

FIG. 11 is an example of a method of displaying the measured values shown in FIGS. 8 and 9. The data conversion device 7 and the arithmetic controller 8 shown in FIG. 1 are connected to a computer 100, which has a display 101 as a display means.
It is equipped with A sectional view 102 representing the measurement position of the object is displayed at the bottom of the display screen of the display 101, and above it, an X-axis representing the position of the measurement point in the axial direction of the object is displayed parallel to the axis of the sectional view. ing. A Y-axis representing the output value measured perpendicular to the X-axis is set, and the measured stress distribution 7 is placed on the X-axis corresponding to the display position of the cross-sectional view.
1 and coercive force distribution 72 are drawn. Furthermore, an X-Y plotter 105 is connected to the computer 100, and the diagram drawn on the display screen of the display 101 is displayed on the X-Y plotter 105.
05, it is output as a hard copy. In this way, this embodiment has the effect that the stress distribution and magnetic property distribution measured by the stress measuring device are visualized in correspondence with the parts of the subject.

FIG. 12 shows an embodiment in which a detection coil for Barkhausen noise measurement is attached to the stress measurement means.

Barkhausen noise is stress (loaded stress + residual stress)
There is a close relationship between the stress and the microstructure of the material, and if the stress is known, changes in the microstructure can be horizontally compared using Barkhausen noise.

The device of this embodiment has a sensor 100 arranged at the center of the magnetic pole of a stress tester 120, and a device body 104 connected to the sensor 100 outside the stress tester 120. The stress tester 120 and the attached bridge circuit, arithmetic unit, etc. are the same as those in the embodiments shown in FIGS. 3 to 5, so illustration and description thereof will be omitted. sensor 100
includes an excitation section in which an excitation coil 102 is wound around a yoke 101, and a detection coil 103 wound in a high magnetic permeability material. Further, the sensor 100 is connected to the measuring device main body 104 by a signal cable 105, and the measuring device main body 104
It includes an oscillator 106 connected to the input side of the sensor 100, a bandpass filter 107 connected to the output side of the sensor 100, and a display 109 connected to the bandpass filter 107 via a rectifier 108.

The oscillator 106 generates a low frequency sine wave or triangular wave (several 7 to
oscillates at a frequency of several tens of Hz), which is power amplified and sent to the sensor 10.
0 to the excitation coil 102.

Barkhausen noise from the subject 110 received by the detection coil 103 passes through the bandpass filter 107, is rectified, and is displayed on the display 109. Parameters such as the maximum amplitude, average amplitude, and pulse height analysis two-frequency spectrum are extracted from the original waveform of the received Barkhausen noise. FIG. 13 shows the relationship between the hardness of the object and Barkhausen noise as a representative example of microstructural parameters.

FIG. 14 shows an embodiment in which the stress measuring means is provided with a detection coil for measuring eddy current. In this embodiment as well, the stress tester is the same as that described in FIGS. 3 to 5, so
Description and illustration will be omitted.

In the figure, a magnetizing coil 111 is placed at the center between the magnetic poles of the stress tester with its center line perpendicular to the surface of the test object, and a detection coil 112 is placed concentrically with the magnetizing coil 111. There is. An alternating current voltage of a constant amplitude is applied to the magnetizing coil 111 to apply a magnetic field 11 to the subject 113.
4, an eddy current 115 is generated in the subject 113.

A voltage induced in the detection coil 112 by this eddy current 115 is detected by the detection coil 112 . As shown in FIG. 15, this voltage is in a proportional relationship with the initial magnetic permeability of the subject 113, so the initial magnetic permeability can be determined from the voltage command value detected by the detection coil 112. The obtained initial magnetic permeability is corrected by the internal stress measured with a stress tester,
Using a reference specimen made of the same material as the specimen, the mechanical properties of the specimen are determined based on the initial magnetic permeability and mechanical property data created in advance.

In addition, if it is permissible to apply a small amount of plastic deformation to the subject 113, an indenter 116 that can move up and down through the inside of both coils is provided on the center line of the magnetization coil 111 and the detection coil. After the initial magnetic permeability of the subject is measured, the indenter 116 is pressed down, for example, by hydraulic pressure to form an indentation on the surface of the subject. Thereafter, the indenter 116 is raised again, and the initial magnetic permeability of the subject is measured in the same manner.

There is a relationship shown in FIG. 16 between the amount of change in the initial magnetic permeability measured in this way and the hardness. In other words, by determining the amount of change in initial magnetic permeability using the above method,
You can know the hardness of 13. The graph shown in FIG. 16 may be obtained in advance for materials having the same composition and the same treatment as the subject. Since internal stress measurement and eddy current measurement are performed at the same location on the test object, the relationship between the tensile strength and internal stress of the test object can also be investigated in the same way.

Furthermore, in the embodiment shown in FIG. 3, a superconducting quantum interference element magnetic sensor in which a superconducting coil is used as an excitation coil and a superconducting pickup coil is disposed may be provided instead of the magnetometer (including a pickup coil). The same effects as the embodiment shown in the figure can be obtained.

〔Effect of the invention〕

According to the present invention, it is possible to limit the stress measurement area of the object to be measured and to detect other magnetic property values and electrical property values from the same area. In equipment where internal stress is localized such as on the inner wall of a container, the other characteristic values mentioned above at the stress measurement position are
This has the effect of being able to be measured using itu.

Also, according to the In-8 itu calculation of the stress and other properties mentioned above,
This has the effect of increasing the reliability of defect inspection and strength evaluation of the object to be measured.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of the non-destructive inspection device according to the present invention applied to a turbine rotor, and FIG. 2 is a side view showing an embodiment of the non-destructive inspection device according to the present invention applied to a reactor pressure vessel. A side view showing an applied example, FIG. 3 is a sectional view showing the main structure of the stress measuring device shown in FIGS. 1 and 2, and FIG.
5 is a sectional view showing another example of the stress measuring device shown in the figure; FIG. 5 is a circuit diagram showing an example of the circuit configuration of the stress measuring device according to the present invention;
0 is a plan view showing an example of magnetic flux distribution when stress is measured using the stress measuring device shown in FIG. 3 or 4. FIG. The figure is a conceptual diagram showing an example of the magnetic properties and stress distribution of the test object measured by the stress measuring device shown in Fig. 3 or 4. Fig. 10 is a front view showing changes in stress of the test object. The figure is a perspective view showing an example of displaying measured values, Fig. 12 is a sectional view showing an embodiment in which a detection coil and an excitation coil for Barkhausen noise are attached to a stress measuring device, and Fig. 13 is an example of displaying Barkhausen noise. FIG. 14 is a perspective view illustrating the configuration of the eddy current detection coil, FIG. 15 is a graph showing an example of the relationship between the initial permeability and the voltage induced in the eddy current detection coil, and FIG.
The figure is a graph showing an example of the relationship between the hardness of the object and the amount of change in initial magnetic permeability. 3... Stress measuring means (stress measuring device) equipped with a magnetometer, 21.32... Magnetometer, 22.33... Probe, 23... Subject, 24... Magnetic circuit, 25・・・
- Coil, 27... Internal stress, 28.36... Excitation coil, 29.31... Pick-up coil, 30.
35... Lines of magnetic force, 41... Measurement probe, 42.
... Compensation probe, 44... Unbalanced current measuring means,
62...Magnetic hysteresis loop, 71...Stress distribution, 72... Coercive force distribution, 73...Residual magnetic flux density distribution, 85...
Stress distribution correction value, 100...computer, 101
...Display means, 102... Excitation coil, 103...
- Detection coil, 106... Oscillator, 111... Magnetic coil, 112... Detection coil.

Claims (1)

[Scope of Claims] 1. In a non-destructive testing apparatus equipped with a stress measuring means for detecting internal stress of a subject using magnetism, the stress measuring means measures magnetic properties specific to the subject and changes thereof. A non-destructive testing device characterized by being equipped with a magnetometer. 2. A stress measuring means that comes into contact with the subject and detects the internal stress of the subject, and a stress measuring means that is provided concentrically with the stress measuring means and that comes into contact with the subject and measures the magnetic properties specific to the subject and changes thereof. A non-destructive testing device equipped with a magnetometer for measurement. 3. Stress measuring means that comes into contact with the subject and detects the internal stress of the subject, and a stress measuring means that is provided between the stress measuring means and the subject and that comes into contact with the subject and measures the unique magnetic properties of the subject. and a magnetometer that measures the change thereof. 4. A magnetometer that comes into contact with the object to measure the magnetic properties and changes thereof unique to the object; A non-destructive testing device equipped with a stress measuring means for detecting stress. 5. The stress measurement means includes a measurement probe that has a core made of a high magnetic permeability material or a soft magnetic material and has an excitation coil and comes into contact with the test object, a compensation probe that has the same specifications as the measurement probe, and the a bridge circuit including a measurement probe and a compensation probe; unbalanced current measuring means for measuring an unbalanced current value of the bridge circuit; Claim 2, further comprising: calculation means for calculating internal stress.
5. The non-destructive testing device according to 4. 6. The nondestructive testing device according to claim 5, wherein the probe is formed in a U-shape, and both ends of the U-shape are magnetic poles that contact the subject. 7. A computer that graphs the internal stress value, coercive force and residual magnetic flux density of the subject outputted from the calculation means, with the measurement position of the subject as one coordinate axis, and a computer that is connected to the computer and displays the graph. 7. The non-destructive testing apparatus according to claim 5, further comprising a display means. 8. The non-destructive testing device according to claim 6, characterized in that a magnetometer is disposed at the center between the magnetic poles. 9. Claims 5, 6, and 8, characterized in that the contact surface of the measurement probe with the subject is rotatable within the contact surface about a center line of the measurement probe perpendicular to the contact surface. non-destructive testing equipment. 10. The non-destructive inspection apparatus according to any one of claims 1 to 9, wherein the object to be inspected is an equipment material or an actual machine member of any one of a chemical plant, a thermal power plant, and a nuclear power plant. 11. A stress measuring means that contacts the subject and detects the internal stress of the subject, and a magnetization coil and a detection coil that are provided concentrically with the stress measuring means and measure eddy currents specific to the subject. Equipped with non-destructive testing equipment. 12. Stress measuring means that comes into contact with the subject and detects the internal stress of the subject, and a Barkhausen device that is provided between the stress measuring means and the subject and that comes into contact with the subject and is unique to the subject. an excitation coil and a detection coil for measuring noise;
A non-destructive testing device comprising: an oscillator that supplies a low frequency voltage to the excitation coil. 13. Excitation means in which the magnetometer applies magnetomotive force to the subject;
11. The nondestructive testing apparatus according to claim 1, further comprising a Hall element that detects magnetic flux induced from the object by an applied magnetomotive force. 14. Claim characterized in that the magnetometer includes a superconducting coil that applies magnetomotive force to the subject, and a superconducting pickup coil that detects magnetic flux induced from the subject by the applied magnetomotive force. 11. The non-destructive testing device according to items 1 to 10. 15. Sequentially apply different values of magnetomotive force to the test object, detect magnetic lines of force induced from the test object by the magnetomotive force to obtain a magnetic hysteresis curve, and determine the magnetic properties of the test object based on the magnetic hysteresis curve. A non-destructive testing method for determining the mechanical properties of the object based on the obtained magnetic properties. 16. The influence of internal stress on the magnetic properties of the specimen is converted into data in advance, and a closed magnetic circuit passing through the specimen and the measurement probe, and a magnetic circuit passing through the reference specimen and the compensation probe are formed, and both magnetic There is a procedure for detecting the internal stress of a test object based on the difference in magnetic resistance of the circuit, and a magnetic hysteresis method by sequentially applying different values of magnetomotive force to the test object and detecting the lines of magnetic force induced from the test object by the magnetomotive force. a step of obtaining a hysteresis curve and obtaining the magnetic properties of the object based on the magnetic hysteresis curve; correcting the magnetic properties using the internal stress obtained in the previous step; and correcting the magnetic properties based on the corrected magnetic properties. A non-destructive testing method for determining the mechanical properties of the object.