Ultrasonic testing specimen and method of manufacturing same

Abstract

To provide a test piece for ultrasonic flaw detection that uses a flat-bottomed hole as an artificial flaw when conducting ultrasonic flaw detection upon a round bar, with which it is possible to eliminate the impact of twice reflected echoes and reliably conduct the sensitivity adjustment of an ultrasonic flaw detection device.SOLUTION: Provided is a test piece S for ultrasonic flaw detection that is used when probing with ultrasonic waves a defect existing on the surface or in the surface layer of a round bar. In a circumferential portion of a body 1 of the same material and of the same diameter as the round bar is formed, as an artificial flaw, a cylindrical flat-bottomed hole 2 where its flat bottom face 21 would cross at right angles a direction in which a flaw detection ultrasonic wave enters, and in at least an opening peripheral part on the flat-bottomed hole 2 side that is close to the circumferential surface of the body 1 in the opening periphery of the flat-bottomed hole 2 is formed an extension part 22 that extends from the circumference surface of the body 1 by a prescribed distance to the outside in a direction of the axis m of the flat-bottomed hole 2.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a test piece for ultrasonic testing used when adjusting the sensitivity of an ultrasonic testing device, and a method for manufacturing the same. [Background technology]

[0002] In this type of ultrasonic test piece, a so-called flat-bottom hole is provided as an artificial flaw, and ultrasonic testing waves are emitted toward the flat bottom surface of the flat-bottom hole, and the sensitivity of the ultrasonic testing device is adjusted so that the reflected ultrasonic wave has a defect echo signal strength of a predetermined value or more (for example, Patent Document 1). When detecting surface flaws or surface layer flaws in a round bar material, as shown in Figure 7, a cylindrical flat-bottom hole 2 of a predetermined length is formed in the surface of a cylindrical test piece body 5 of the same material and diameter as the round bar material to be tested. The flat-bottom hole 2 is angled so that its flat bottom surface 21 is perpendicular to the direction in which the ultrasonic testing waves are incident.

[0003] That is, when detecting surface flaws or subsurface flaws in a round bar material, oblique angle testing is performed so that the refraction angle θ of the detection ultrasound is, for example, 45° to 55°. The flat-bottom hole 2 is formed at an angle such that the flat-bottom surface 21 is perpendicular to the detection ultrasound incident on the test piece S from the detection probe 4 at such a refraction angle θ, and the round bar material is rotated to adjust the sensitivity of the ultrasonic testing device so that the defect echo of the reflected ultrasound is equal to or greater than a predetermined value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication 2019-78558 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned conventional ultrasonic test piece S, the reflected ultrasonic waves from the flat-bottomed hole 2 formed in the test piece body 5 include not only a defect echo Ed that is reflected and returned by the flat bottom surface 21 of the flat-bottomed hole 2, but also a double-reflection echo En that is reflected by the peripheral surface of the round bar material and the side surface of the flat-bottomed hole 2 close to it, because the ultrasonic waves for flaw detection have a certain spread.

[0006] In this case, when detecting flaws in a small-diameter round bar material, the test piece S is also made smaller in diameter accordingly. In this case, however, the defect echo Ed from the flat-bottom hole 2 and the double-reflection echo En return to the flaw detection probe 4 close in time, and therefore, as shown in Figure 8, in addition to the defect echo signal Eds, the double-reflection echo signal Ens also appears within the detection window (time width) T of the ultrasonic flaw detection device, and they cannot be distinguished from each other. This creates a problem in that the intended purpose of adjusting the sensitivity of the ultrasonic flaw detection device by rotating the round bar material so that the defect echo signal Eds of the reflected ultrasonic waves is equal to or greater than a predetermined value cannot be achieved.

[0007] The present invention is intended to solve such problems, and provides a method for ultrasonically detecting flaws in a round bar material. Use This enables accurate adjustment of the sensitivity of ultrasonic testing equipment by eliminating the effect of double-reflection echoes in ultrasonic testing test pieces. Providing ultrasonic test pieces The purpose is [Means for solving the problem]

[0008] In order to achieve the above object, the first invention is an ultrasonic test piece used for ultrasonically detecting defects present on the surface or surface layer of a round bar material, The test piece (S) is a columnar body made of the same material as the round bar material, and an artificial flaw (2) is provided on the surface of the test piece (S). The test piece (S) has a main body (1) having a circular cross section with the same diameter as the round bar material, and a protruding portion (11) having a cross section whose contour is a partial arc of the circular cross section, a straight line connecting one end point (c) of the partial arc and a point on a tangent to the one end point (c), and a line connecting the point on the tangent to the other end point of the partial arc and perpendicular to the straight line, and the artificial flaw (2) is a hole formed in a surface (111) of the protruding portion (11) corresponding to the line, the hole penetrates the protruding portion (11), and a part of the hole including a tip (21) is formed in the main body (1). .

[0009] The first invention According to the data, Because the reflection path of the flaw detection ultrasonic wave is made longer than the reflection path from the artificial flaw, the defect echo and the double-reflected echo return to the flaw detection probe with a sufficient time separation between them. Therefore, the ultrasonic flaw detection device can reliably distinguish between the defect echo and the double-reflected echo, and the sensitivity of the ultrasonic flaw detection device can be reliably adjusted so that the defect echo signal is equal to or greater than a predetermined value without being affected by the double-reflected echo.

[0010] The second invention In the embodiment, the hole (2) is a cylindrical flat-bottom hole, and an extension (22) of a constant cross-sectional thickness is formed between the straight line of the protrusion (11) and the side surface of the flat-bottom hole (2). .

[0011] According to the second invention, by forming the extension, the defect echo of the flaw detection ultrasonic wave is reflected back by the flat bottom surface of the flat bottom hole, and the double reflected echo is reflected back by the tip of the extension that is sufficiently far away from the flat bottom surface. Therefore, the defect echo and the double reflected echo return to the flaw detection probe with a sufficient time difference between them, so that the ultrasonic flaw detection device can reliably distinguish between them and reliably adjust the sensitivity of the ultrasonic flaw detection device so that the defect echo signal is equal to or greater than a predetermined value without being affected by the double reflected echo.

[0012] In the third invention, the radius (r) of the main body, the diameter (D) of the flat-bottom hole, and the thickness (W) of the extension portion have the following relationship: W = r-(rsinθ+D / 2) Here, W>λ, λ is the wavelength of the ultrasonic wave, and θ is the refraction angle of the ultrasonic wave.

[0015] The reference characters in parentheses indicate, for reference, the correspondence with specific means described in the embodiments described later. Effect of the Invention

[0016] As described above, according to the ultrasonic testing test piece and the manufacturing method thereof of the present invention, in an ultrasonic testing test piece in which a flat-bottom hole is used as an artificial flaw when performing ultrasonic testing on a round bar material, the influence of double-reflection echoes can be eliminated and the sensitivity of the ultrasonic testing device can be reliably adjusted. [Brief description of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of a test piece for ultrasonic flaw detection, showing one embodiment of the present invention. [Diagram 2] FIG. 2 is an overall perspective view of a test piece body used in manufacturing a test piece for ultrasonic flaw detection. [Diagram 3] FIG. 2 is a side view and an end view of the test specimen body. [Figure 4] FIG. 2 is a partially enlarged side view of a test piece body having a flat-bottom hole formed therein. [Diagram 5] 4 is a diagram showing changes over time in a reflected ultrasonic signal received by an ultrasonic flaw detector. FIG. [Figure 6] FIG. 4 is a cross-sectional view of a test piece for ultrasonic inspection showing another embodiment of the present invention. [Figure 7] FIG. 1 is a cross-sectional view of a conventional ultrasonic testing specimen. [Figure 8] FIG. 2 is a diagram showing changes over time in a reflected ultrasonic signal received by an ultrasonic flaw detector. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] It should be noted that the embodiment described below is merely an example, and various design improvements made by those skilled in the art without departing from the gist of the present invention are also included in the scope of the present invention.

[0019] Fig. 1 shows an example of a cross section of the ultrasonic test piece S of the present invention. In Fig. 1, the body 1 of the ultrasonic test piece S is columnar and has a circular cross section with the same diameter as the round bar material to be tested. A cylindrical flat-bottom hole 2 is formed as an artificial flaw such that its flat bottom surface 21 is perpendicular to the direction of incidence of the ultrasonic wave, which is incident on a point a on the circumferential surface of the test piece body 1 from a flaw detection probe (not shown) and propagates through the body 1 at a refraction angle θ.

[0020] In this embodiment, the flat-bottom hole 2 is drilled in a protruding portion 11 formed on a part of the circumferential surface of the test piece body 1. Circumferential surface (virtual) An extension 22 is formed on the upper edge of the opening on the side closest to the test piece body 1. Circumferential surface It extends outward from the axis m of the flat-bottom hole 2 with a constant thickness W, and its tip 221 is flat.

[0021] In addition, the symbols r, D, W, and H in FIG. 1 indicate the dimensions of the following parts. r: radius of specimen body D: Flat bottom hole diameter W: Thickness of extension H: Extending amount (= flat bottom hole depth)

[0022] Here, there is a relationship of W=r-(rsinθ+D / 2), and the larger W is made, the smaller the effect of the double reflected echo can be, but D becomes smaller accordingly, and the defect echo reflected by the flat bottom surface 21 becomes weaker. Therefore, taking this into consideration, it is necessary to appropriately adjust the sizes of W and D. Note that, when the wavelength of the flaw detection ultrasonic wave is λ, W must be greater than λ.

[0023] Furthermore, the larger H is, the better the separation of defect echoes and double-reflection echoes can be achieved. The magnitude of H must be set to be greater than or equal to the pulse duration of the flaw detection ultrasonic wave. For example, if the sound speed of the flaw detection ultrasonic wave is 3000 m / s, the frequency is 10 MHz, and the wave number is 3, the magnitude of H must be secured to be 0.9 mm or greater.

[0024] The test piece S with the extension 22 formed thereon is manufactured, for example, as follows. That is, a columnar body of a certain length X made of the same material as the round bar is formed by machining or the like into a test piece body 1 as shown in a perspective view in Fig. 2 and in a side view and an end view in Fig. 3(1) and (2), respectively. The length X of the test piece body 1 need only be longer than the length of the flaw detection probe 4 used (the length perpendicular to the paper surface in Fig. 1).

[0025] The test piece body 1 has a circular cross section with the same diameter as the round bar material for the most part, and a protruding portion 11 protruding radially outward at a part of the circumference. The cross section of this protruding portion 11 is bounded by a tangent line from a point c on the circumference above the circular cross section and a line perpendicular to the tangent line extending from the point c on the circumference below the circular cross section. Then, at one point in the longitudinal direction of this protruding portion 11, a cylindrical flat-bottomed hole 2 is drilled in the lower inclined surface 111 of the protruding portion 11 in parallel with the upper inclined surface 112, as shown in FIG. 4. This forms the above-mentioned extension portion 22 of a predetermined thickness W at the upper edge of the opening of the flat-bottomed hole 2.

[0026] By forming such an extension 22, as shown in Fig. 1, a defect echo Ed of the flaw detection ultrasonic wave is generated by reflection on the flat bottom surface 21 of the flat-bottom hole 2, while a double-reflection echo En is generated by reflection on the flat surface of the tip 221 of the extension 22, which is separated from the flat bottom surface 21. Therefore, the defect echo Ed and the double-reflection echo En return to the flaw detection probe with a sufficient time separation, and only the defect echo signal Eds appears within the detection window T of the reflected ultrasonic signal received by the ultrasonic flaw detection device, as shown in Fig. 5. This makes it possible to reliably adjust the sensitivity of the ultrasonic flaw detection device so that the defect echo signal Eds of the reflected ultrasonic wave is equal to or greater than a predetermined value.

[0027] The protrusion formed on the test piece body does not necessarily have to have the cross section as described above, and the method of forming the extension around the opening edge of the flat-bottom hole of the test piece is not limited to the method described above. In this case, depending on the formation method, the extension amount of the extension may not be the same as the depth of the flat-bottom hole, unlike the above embodiment. The thickness of the extension does not necessarily have to be constant, and it may be one that gradually increases in thickness toward the tip. Furthermore, the tip of the extension does not necessarily have to be flat. More specifically, for example, an artificial flaw 6 that does not have a flat bottom as shown in Figure 6(1) may be formed. or, For an artificial flaw 7 formed at a certain depth from the surface as shown in Fig. 6(2), the same effect as in the above embodiment can be obtained by forming the extensions 61, 71 as shown in the figure. Also, the test piece of the present invention can be used with either a single transducer or a phased array type flaw detection probe. [Explanation of symbols]

[0028] 1...Main body, 11...Protruding part, 2...Flat bottom hole, 21...Flat bottom surface, 22...Extending part, S...Test piece for ultrasonic flaw detection.

Claims

1. An ultrasonic test piece used for ultrasonically detecting defects on the surface or surface layer of a round bar material, The test piece is a columnar body made of the same material as the round bar material, An artificial flaw is provided on the surface of the test piece, The test piece is A main body having a circular cross section with the same diameter as the round bar material; a protrusion having a cross section defined by a contour of a partial arc of the circular cross section, a straight line connecting one end point of the partial arc and a point on a tangent to the one end point, and a line connecting the point on the tangent to the other end point of the partial arc and perpendicular to the straight line; having The artificial flaw is a hole formed in a surface corresponding to the line of the protrusion; The hole penetrates the protrusion, and a portion of the hole, including the tip, is formed in the main body.

2. An ultrasonic flaw detection test piece as described in claim 1, wherein the hole is a cylindrical flat-bottom hole, and an extension portion of a constant cross-sectional thickness is formed between the straight line of the protrusion and the side of the flat-bottom hole.

3. 3. The ultrasonic test piece according to claim 2, wherein the radius (r) of the body, the diameter (D) of the flat-bottom hole, and the thickness (W) of the extension portion have the following relationship: W=r-(rsinθ+D / 2) Here, W>λ, λ is the wavelength of the ultrasonic wave for flaw detection, and θ is the refraction angle of the ultrasonic wave for flaw detection.

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