JPH0752180B2 - Ultrasonic testing method - Google Patents

Description

Description: [Object of the Invention] (Field of Industrial Application) The present invention relates to an ultrasonic flaw detection test method in which a ceramic member is subjected to an oblique angle method using a standard test piece for ultrasonic flaw detection test.

(Prior Art) Conventionally, an ultrasonic flaw detection test method has been used as a method for nondestructively detecting internal defects such as pores and foreign matters in a ceramics sintered body.

In this method, the ultrasonic wave (transducer) of the ultrasonic flaw detector is moved while being in contact with the surface of the ceramic sintered body via a contact medium such as water or oil, and reflected waves reflected from the defective portion. Is a method of detecting the existence of a defect, its size, its position, and the like. According to this ultrasonic flaw detection test, even a fine internal defect can be detected, so that it has been rapidly put into practical use in recent years as a nondestructive inspection method.

This ultrasonic flaw detection test is roughly classified into a vertical method and an oblique angle method according to the method of injecting ultrasonic waves into the subject. According to the oblique angle method, it is possible to detect a complex-shaped member, Since the width of the insensitive body near the incident surface due to echo is narrowed and flaw detection can be performed up to the vicinity of the incident surface, it is possible to accurately perform non-destructive inspection even on extremely thin members. Has been tried to apply.

In order to perform an ultrasonic flaw detection test by such an oblique angle method, the refraction angle with respect to the incident angle of ultrasonic waves, and the transverse wave is used in the oblique angle method, so the appearance state of the transverse wave and the longitudinal wave with respect to the incident angle is grasped. Is needed. Further, the position of the detected defect cannot be accurately known unless the time axis of the obtained waveform is set accurately, not limited to the bevel method.

By the way, the ultrasonic flaw detection test by the oblique angle method for the current ceramic members is performed by converting the measured value by the standard test piece for steel materials from the density difference of the test object or the sound velocity difference in the test object, and the incident angle as described above. The flaw detection is performed by obtaining the entrance / reflection characteristics and the propagation characteristics determined by the material of the ceramic member, such as the refraction angle with respect to, the appearance state of the transverse wave and the longitudinal wave with respect to the incident angle, the setting of the time axis in the detection waveform, and the like.

(Problems to be solved by the invention) However, in the flaw detection method of the ceramic member using the value obtained by converting the measured value by the standard test piece for steel material as described above, the accurate position of the detected defect cannot be evaluated, The reliability of the ultrasonic flaw detection test was significantly reduced.

In addition, although the incident point of the ultrasonic probe is usually clarified, the incident point may be displaced due to wear of the contact medium with use, etc. The current situation is that there are none.

The present invention has been made to cope with such a current situation,
An object of the present invention is to provide an ultrasonic flaw detection test method that makes it possible to accurately evaluate the position of a defect in an ultrasonic flaw detection test of a ceramic member by the oblique angle method and improve reliability.

[Structure of the Invention] (Means for Solving the Problems) The ultrasonic flaw detection test method of the present invention comprises a homogeneous ceramics sintered body having a predetermined shape and size, and at least a curved surface having a predetermined radius of curvature. An ultrasonic wave is incident on the curved reflecting surface at an incident angle of 16 ° or more from an ultrasonic wave incident surface of an ultrasonic flaw detector standard test piece having a reflecting surface, and the ultrasonic wave in the ultrasonic test specimen standard test piece After clarifying the incident / reflection characteristics and / or the propagation characteristics, ultrasonic waves are incident from the surface of the ceramic member to be inspected at an incident angle of 16 ° or more, and the ultrasonic wave incident / reflection characteristics and / or Alternatively, it is characterized in that the propagation characteristic is measured.

The standard test piece for ultrasonic flaw detection test made of the sintered ceramics of the present invention is most preferably made of the same material as the ceramic member to be inspected. The input / reflection characteristics of an ultrasonic wave in a solid, that is, the refraction angle at the time of incidence on the solid and the propagation characteristics in the solid are determined by the density of the test object and the contact medium between the test object and the probe and the test object and the contact medium. Since it is determined by the speed of sound inside, determining the above characteristics with a standard test piece of the same material as the test subject gives the most reliable test results, but as shown in the table below, Since the difference in sound velocity and the difference in theoretical density between ceramics sintered bodies are much smaller than the difference between these values and steel materials, other ceramics sintered bodies can be diverted depending on the inspection accuracy. .

Further, the ceramic sintered body used as a standard test piece for ultrasonic flaw detection test is preferably one having excellent homogeneity by a hot pressing method or the like because the propagation of ultrasonic waves is stable, and the relative density with respect to the theoretical density is 90% or more. The ones are suitable.

Furthermore, the incident angle of ultrasonic waves used for measurement must be 16 ° or more. This is because the received sound pressure of the reflected wave is stabilized by setting the incident angle to 16 ° or more.

(Operation) By using the above means, it is possible to clarify the ultrasonic wave incident / reflection characteristics and propagation characteristics in the oblique angle method for the ceramic member, and perform ultrasonic flaw detection of the ceramic member by the oblique angle method. It is possible to accurately evaluate the position of the defective portion in case of damage, and the reliability is greatly improved.

(Example) Next, the Example of this invention is described in detail, referring drawings.

FIG. 1 is a perspective view showing an embodiment of a standard test piece for ultrasonic flaw test used in the ultrasonic flaw test method of the present invention. The standard test piece for ultrasonic flaw test 1 is a rectangular parallelepiped having a predetermined size. (In this embodiment, l = 100 mm, w = 17 mm, h = 25 mm
And ), One end face in the longitudinal direction, a silicon nitride sintered body by the hot pressing method in the shape of a curved surface 1c having a radius of curvature of the same dimension as one side of this end face, TSN-02 (trade name, manufactured by Toshiba Corporation, burned The density is 3.2 g / cm ³ ) and the upper surface 1a is the basic ultrasonic wave incident surface and the curved surface 1c is the reflecting surface for determining characteristics. The standard test piece 1 for ultrasonic flaw detection has a re-reflection notch 2 used for determining the incident point on one side surface 1b. The re-reflection notch 2 has a rectangular cross section. It is formed in parallel with the other end surface facing the curved surface 1c and one side of the rectangular cross section on the curved surface 1c side is overlapped with the center of curvature of the curved surface 1c. further,
Through holes 3 are formed in the standard test piece 1 for ultrasonic flaw detection test in parallel to the upper surface 1a from one side surface to the other side surface. The re-reflecting notch 2 and the through hole 3 are formed to have predetermined dimensions, as shown in FIGS. 2 and 3.

FIG. 4 is a perspective view showing a standard test piece for ultrasonic flaw detection test of another embodiment. The standard test piece 4 for ultrasonic flaw detection test is the standard test piece for ultrasonic flaw detection test in the above-mentioned embodiment. A rectangular parallelepiped (l = 100 mm, w = 17 mm, h = 50 mm in this embodiment) having a predetermined size and made of the same material as the piece, and has a basic ultrasonic wave incident surface from one side surface to the other side surface. Through hole 5 with a perfect circular cross section parallel to the upper surface 4a and the end surface
Are formed. The through hole 5 has a predetermined diameter and is formed at a predetermined position, as shown in FIG.

Next, a method of determining the ultrasonic wave input / reflection characteristics and propagation characteristics required when performing an ultrasonic flaw detection test using these standard test pieces for ultrasonic flaw detection tests will be described.

First, measurement is performed using the standard test piece 1 for ultrasonic flaw detection test shown in FIG. A contact type variable angle probe was used as the probe, and measurement was performed at a frequency of 10 MHz. Also, the second
The dimension of the re-reflection notch 2 in the drawings and FIG. 3 is i
= 10 mm, j = 0.5 mm, k = 2 mm.

(Setting of Time Axis) As shown in FIG. 6, the probe 6 is arranged on the upper surface 1a of the standard test piece 1 for ultrasonic flaw detection test so that the incident point is on the center of curvature of the curved surface 1c. Ultrasonic waves are incident on the curved surface 1c at a right angle. This incident ultrasonic wave is reflected by the curved surface 1c and received by the probe 6, but a part thereof is re-reflected by the re-reflection notch 2, and this re-reflected wave is reflected again by the curved surface 1c. The probe 6 receives it as an echo of the re-reflected wave and obtains a detected wave as shown in FIG. In the figure, the first echo 7 is an echo upon incidence, the second echo 8 is an echo of the first reflected wave, and the third echo 9 is an echo of a re-reflected wave. As is clear from the figure, the echo 7 at the time of incidence becomes gentle due to the resistance at the time of incidence, and it is impossible to accurately specify the time of incidence, so the echo 8 and the re-reflected wave due to the first reflected wave An accurate time axis can be set from the time difference t from the echo 9 and the ultrasonic path length and sound velocity determined by the shape of the standard test piece 1 for ultrasonic flaw detection test. If the re-reflection notch 2 is not formed, the first reflected wave is reflected by the upper surface 1a at the same angle as the refraction angle θ ₂ at the time of incidence in the direction opposite to the curved surface, and thus the re-reflection is performed. It is not possible to detect wave echoes.

Further, the setting of this time axis is not limited to the reflection by the curved surface 1c as long as it is after the measurement of the refraction angle at the time of incidence of the ultrasonic wave, and the ultrasonic wave incident on another surface, for example, the upper surface 1a and reflected on the lower surface. It is possible because each dimension is also fixed by receiving the.

(Measurement of the incident point) This measurement of the incident point is not usually required because the incident point is clearly defined on the probe, but there may be a deviation due to wear of the contact medium depending on the frequency of use, This is performed for correction in such a case.

The ultrasonic wave with the probe arranged at the same position as described above (setting of the time axis) is incident. At this time, if the incident point is deviated from the center of curvature of the curved surface 1c, the incident ultrasonic wave does not hit the curved surface 1c at a right angle, and even if this reflected wave can be received, the received sound pressure decreases. Therefore, while the probe 6 is being scanned, the incidence and reception of ultrasonic waves are repeated to find the position where the sound pressure is maximum, and this position becomes the incident point. Then, at this position, an echo due to re-reflection of the ultrasonic wave is detected using the re-reflection notch 2 by the same procedure as described above (setting of the time axis), and the time difference from the echo due to the first reflection is detected. Accurately determine the incident point by measuring the distance of the ultrasonic path.

(Detection of Appearance State of Longitudinal Wave and Transverse Wave by Incident Angle) When performing ultrasonic flaw detection test by injecting ultrasonic waves by the oblique angle method, transverse waves are used. Since the appearance states of the longitudinal wave and the transverse wave are determined by the incident angle θ ₁ and the refraction angle θ ₂ at the time of ultrasonic wave incidence, the re-reflected wave at (time axis setting) is received while changing the incident angle θ _1. To avoid this, the same procedure is performed except that light is incident from a position that is not affected by the re-reflection notch 2, and each echo is identified from the difference in sound velocity between the longitudinal wave and the transverse wave from the obtained detected waveform, and Calculated from the sound pressure of. An example of this measurement result is silicon nitride ceramics as a standard test piece 1 for ultrasonic flaw detection test,
Further, an acrylic resin is used as the probe 6, and the incident angle θ ₁
And the received sound pressures of the longitudinal wave and the transverse wave are graphed and shown in FIG.

As is clear from this graph, in this example, the longitudinal wave is attenuated at an incident angle of about 16 degrees, and the transverse wave is incident angle.
Since it stabilizes from around 16 degrees, accurate flaw detection can be performed by using this stable incident angle at which transverse waves appear.

It is possible to measure the refraction angle by using the through hole 3 also in the standard test piece 1 for ultrasonic flaw detection test, but a curved surface having a radius of curvature of a certain degree or more is required for accurate measurement. Therefore, the refraction angle is measured by using the standard test piece for ultrasonic flaw detection test shown in FIG. 4 as another embodiment.

Next, measurement is performed using the standard test piece 4 for ultrasonic flaw detection test shown in FIG. The contact type fixed angle probe (incident angle θ ₁ = 18.6 degrees) was used as the probe, and the ultrasonic frequency was 10 MHz.
The measurement was performed at z. The size of the through hole 5 is 25 mm in diameter.
(= P), and the position was set to m = 35 mm and n = 17.5 mm.

(Measurement of Refraction Angle) As shown in FIG. 9, the probe 6 is placed on the upper surface 4a of the standard test piece 4 for ultrasonic flaw detection, and the probe 6 is placed so that it is perpendicular to the longitudinal direction of the through hole 5. Inject sound waves. At this time, if the ultrasonic wave incident at a constant refraction angle θ ₂ is not incident at a right angle to the circumferential surface of the through hole 5, the reflected wave cannot be received, or even if it can be received. The received sound pressure drops. Therefore, by repeating the incidence and reception of ultrasonic waves while scanning the upper surface 5a under such conditions,
The position where the maximum sound pressure is detected is detected, and the refraction angle θ ₂ is obtained from the distance x from the end face at this position as follows. In this example, the measurement result of x = 52.5 mm was obtained.

Here, the value of m is 35 mm, and the value of y is n = 17.5 mm, which is 35 mm from the measurement result x, so that tan θ ₂ = 35 ÷ 35 = 1 ∴ θ ₂ = 45 degrees.

Although the contact type probe has been described in these examples, it is needless to say that even when the incident angle is changed by the water immersion method, the ultrasonic input / reflection characteristics and the propagation characteristics are similarly set. It is possible to clarify.

As described above, according to these examples, it is necessary as basic data when performing the ultrasonic flaw detection test by the oblique angle method on the silicon nitride sintered body as an example of the ceramic member. It is possible to clarify the setting of the time axis, the refraction angle with respect to the incident angle, the incident point, the appearance state of the longitudinal wave and the transverse wave with respect to the incident angle, and these values accurately evaluate the defect position in the ultrasonic flaw detection test. It becomes possible.

(Ultrasonic flaw detection test of specimen) 140 × 1 made of silicon nitride sintered body by hot press method
A 40 × 10 mm flat plate was produced. A contact type fixed-angle probe was used as a contactor on this flat plate, and scanning was performed on the surface of the flat plate while injecting an ultrasonic wave of 18.6 degrees and a frequency of 10 MHz.
As a result, the defect echo was detected and its position was known. The height of the echo also revealed the size of the defect. Moreover, when the site where this defect echo was observed was cut, it was found to be a vacancy.

The shape of the standard test piece for ultrasonic flaw detection test of the present invention is
The present invention is not limited to these examples, and various shapes can be considered as long as the same effect can be obtained. Further, in the above-mentioned examples, the standard test piece for ultrasonic flaw detection test using the silicon nitride sintered body as the ceramic sintered body was described, but other ceramic sintered bodies are similarly subjected to the ultrasonic flaw detection test. It is possible to clarify the characteristics by making a standard test piece.

[Effects of the Invention] As is clear from the above examples, according to the ultrasonic flaw detection test method of the present invention, the ultrasonic wave entrance / reflection characteristics and the propagation characteristics of the ceramic member by the oblique angle method are measured. It is possible to obtain numerical values, and by using these numerical values, it is possible to accurately evaluate the defect position in the ultrasonic flaw detection test by the bevel method, and the reliability as a nondestructive inspection is significantly improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a standard test piece for ultrasonic flaw detection test according to an embodiment of the present invention, FIGS. 2 and 3 are top and side views thereof, and FIG. 4 is another embodiment of the present invention. FIG. 5 is a perspective view showing a standard test piece for ultrasonic flaw detection test, FIG. 5 is a side view thereof, and FIG. 6 is a schematic view showing a characteristic determining method using the standard test piece for ultrasonic flaw detection test shown in FIG. FIG. 7, FIG. 7 is a diagram showing a detected waveform as an example of the measurement result, FIG. 8 is a graph showing an example of the measurement result as a function of incident angle and received sound pressure of longitudinal wave and transverse wave, and FIG. It is a figure which shows roughly the characteristic determination method using the standard test piece for an ultrasonic flaw detection test shown in FIG. 1, 4 ... Standard test piece for ultrasonic flaw detection 2 ... Notch for re-reflection 3, 5 ... Through hole

Claims (7)

[Claims] 1. A standard test piece for ultrasonic flaw detection test, which is made of a homogeneous ceramics sintered body having a predetermined shape and size, and has a curved reflecting surface having at least a predetermined radius of curvature. After the ultrasonic waves are incident on the curved reflecting surface at the above incident angles to clarify the ultrasonic wave input / reflection characteristics and / or propagation characteristics in the standard test piece for ultrasonic flaw detection test, a ceramic to be an object to be inspected An ultrasonic flaw detection test method, which comprises injecting ultrasonic waves at an incident angle of 16 ° or more from the surface of a member and measuring the ultrasonic wave incident / reflection characteristics and / or propagation characteristics of the subject. 2. The ultrasonic flaw detection test method according to claim 1, wherein an ultrasonic wave incident point is determined when clarifying the entrance / reflection characteristics and / or propagation characteristics of a standard test piece for ultrasonic flaw detection test. . 3. The ultrasonic flaw detection test method according to claim 1 or 2, wherein the standard specimen for ultrasonic flaw detection test is made of the same material as the ceramic member to be inspected. 4. The ultrasonic flaw detection according to any one of claims 1 to 3, wherein the standard test piece for ultrasonic flaw detection has a relative density of 90% or more with respect to the theoretical density of the ceramic sintered body. Test method. 5. A standard test piece for ultrasonic flaw detection is made of a ceramic sintered body in which one end face in the longitudinal direction of a rectangular parallelepiped having a predetermined size is a curved surface which becomes a reflecting surface having a radius of curvature having the same size as one side of this end face. The ultrasonic flaw detection test method according to any one of claims 1 to 4. 6. A standard test piece for ultrasonic flaw detection has a cutout portion having a rectangular cross section on a side surface adjacent to a curved surface, and the cutout portion is parallel to the other end surface facing the curved surface and has a rectangular cross section. The ultrasonic flaw detection test method according to claim 5, wherein one side of the curved surface is formed so as to overlap the center of curvature of the curved surface. 7. A standard test piece for ultrasonic flaw detection test is made of a rectangular parallelepiped-shaped ceramics sintered body having a through-hole having a circular cross-section forming a curved reflecting surface, and the through-hole is the through-hole. The ultrasonic flaw detection test method according to any one of claims 1 to 4, which is parallel to a surface other than the formation surface.