Contrast reflector for evaluating point defects through ultrasonic flaw detection

Abstract

The utility model discloses a contrast reflector for evaluating point defects by ultrasonic flaw detection, which comprises a plate-shaped reflector body, the neutral surface of the reflector body is trapezoidal, two waists of the reflector body are respectively provided with a plurality of steps, and a detection hole is arranged on the surface of each step parallel to the lower bottom of the reflector body; wherein the detection hole in one waist of the reflector body is a conical hole, and the detection hole in the other waist of the reflector body is a cylindrical hole. According to the utility model, cylinder-like or cone-like point-like defects in the welding seam can be accurately evaluated.

Description

Technical Field

[0001] The utility model belongs to the technical field of construction engineering detection and nondestructive detection, and in particular relates to a contrast reflector for evaluating point defects using ultrasonic flaw detection. Background Art

[0002] In the ultrasonic flaw detection of welds in building steel structures, as shown in Figure 1 (a), there is a defect of lack of fusion or lack of penetration between weld layers during double-sided welding of X-groove. This defect is similar to a cone with two vertices facing each other and is recorded as a conical defect. As shown in Figure 1 (b), for V-groove welds, some of the unfused point defects in the weld are similar to cylinders, such as root unfused or lack of penetration defects or defects that are covered after penetration, which are recorded as cylindrical defects. These defects are quite different from the geometric shape of the Φ3mm transverse hole reflector on the RB test block. If the Φ3mm transverse hole reflector is used to evaluate such defects, a large error will occur. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the purpose of the utility model is to provide a contrast reflector for evaluating point defects by ultrasonic flaw detection. The utility model can more accurately evaluate point defects similar to cylinders or cones in welds.

[0004] The technical solution adopted by the utility model is as follows:

[0005] A contrast reflector for ultrasonic flaw detection and evaluation of point defects includes a plate-shaped reflector body, the neutral surface of the reflector body is trapezoidal, two waists of the reflector body are provided with a plurality of steps, and a detection hole is provided on the surface of each step parallel to the lower bottom of the reflector body; wherein the detection hole on one waist of the reflector body is a conical hole, and the detection hole on the other waist of the reflector body is a cylindrical hole.

[0006] Preferably, the number of steps on each waist of the reflector body is 3 to 6.

[0007] Preferably, the detection hole is arranged at the center of a surface on the step parallel to the lower bottom of the reflector body.

[0008] Preferably, the tolerance grade of the conical hole and the cylindrical hole is the same as the tolerance grade of the reflector hole on the RB test block.

[0009] Preferably, the height of the conical hole is 3 mm and the bottom diameter is 3 mm.

[0010] Preferably, the bottom diameter of the cylindrical hole is 3 mm and the height is 3 mm.

[0011] Preferably, the height of the step is 15-30 mm.

[0012] Preferably, the width of the step is 15-30 mm.

[0013] Preferably, the length of the upper bottom of the reflector body is 120-160 mm.

[0014] Preferably, the length of the lower bottom of the reflector body is 280-320 mm.

[0015] The utility model has the following beneficial effects:

[0016] The utility model ultrasonic flaw detection evaluates the contrast reflector of point defects. Whether the geometric characteristics of the contrast reflector used in the flaw detection are adapted to the type of defect to be detected has a great influence on the evaluation of welding defects. This has been proved by many scholars at home and abroad in this regard. On-site welding of building steel structure projects often encounters complex welding nodes and weld intersections. According to the detection experience, the utility model finds that the point defects formed in the middle of the weld are similar to cones, and the point defects at the root are similar to cylinders. The geometric morphology of the cylindrical hole and the conical hole of the contrast reflector of the utility model is similar to the actual defect geometric morphology. The echo energy of the ultrasonic wave incident on the artificial cylinder and cone reflector is similar to the echo reflection state of the actual flaw detection defect. The difference between the geometric morphology of the defect and the artificial reflector is eliminated to form an energy difference. The echo energy reference value with the known scale cylinder and cone as the reference is used to evaluate the scale error of the cone type in the middle of the weld and the cylinder type defect at the root of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 (a) is a schematic diagram of a conical defect in double-sided welding of an X-groove; Figure 1 (b) is a schematic diagram of a cylindrical defect in a V-groove weld;

[0018] FIG2(a) is a front view of a contrast reflector for evaluating point defects by ultrasonic flaw detection of the present invention; FIG2(b) is a left view of FIG2(a); FIG2(c) is a right view of FIG2(a); and FIG2(d) is a top view of FIG2(a);

[0019] Figure 3 This is a diagram showing the use status of the contrast reflector for ultrasonic flaw detection and evaluation of point defects in the utility model;

[0020] Figure 4 It is the distance-amplitude curve obtained in the embodiment of the utility model.

[0021] In the figure, 1-steel structure, 2-X-type groove double-sided welding, 3-interlayer lack of fusion or incomplete penetration defect, 4-V-type groove weld, 5-root lack of fusion or incomplete penetration defect or penetration covered defect, 6-reflector body, 6-1-step, 6-2-top surface, 6-3-cylindrical hole, 6-4-conical hole, 7-1-first probe, 7-2-second probe. DETAILED DESCRIPTION

[0022] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0023] As shown in Fig. 2 (a)-Fig. 2 (b), the contrast reflector for ultrasonic flaw detection and evaluation of point defects of the utility model comprises a plate-shaped reflector body 6, the neutral plane of the reflector body 6 (i.e., the longitudinal plane in the orientation shown in Fig. 2 (a)) is in the shape of a trapezoid, and the two waists of the reflector body 6 are provided with a plurality of steps 6-1, and a detection hole is provided on the surface (the horizontal surface of the step 6-1 in the orientation shown in Fig. 2 (a)) parallel to the lower bottom of the reflector body 6 (i.e., the relatively longer bottom edge of the reflector body 6) on each step 6-1; wherein, the detection hole on one waist of the reflector body 6 (the left waist in the orientation shown in Fig. 2 (a)) is a conical hole 6-4, and the detection hole on the other waist of the reflector body 6 (the right waist in the orientation shown in Fig. 2 (a)) is a cylindrical hole 6-3.

[0024] As a preferred embodiment of the above scheme of the utility model, the number of steps 6-1 on each waist of the reflector body 6 is 3 to 6. The detection hole is set at the center of the horizontal plane of the step 6-1. The tolerance grade of the conical hole 6-4 and the cylindrical hole 6-3 is the same as the tolerance grade of the reflector hole on the RB test block. The nominal dimensions of the conical hole 6-4 are 3mm in height and 3mm in bottom diameter. The nominal dimensions of the cylindrical hole 6-3 are 3mm in bottom diameter and 3mm in height. The height of the step 6-1 is 15 to 30mm. The width of the step 6-1 is 15 to 30mm. The length of the upper bottom of the reflector body 6 (i.e., the relatively shorter bottom edge of the reflector body 6) is 120 to 160mm. The length of the lower bottom of the reflector body 6 is 280 to 320mm.

[0025] Example

[0026] In this embodiment, the two waists of the reflector body 6 are each provided with four steps 6-1, the detection hole on the left waist of the reflector body 6 is a conical hole 6-4, and the detection hole on the right waist of the reflector body 6 is a cylindrical hole 6-3. The detection hole is set at the center of the horizontal plane of the step 6-1. The tolerance grade of the conical hole 6-4 and the cylindrical hole 6-3 is the same as the tolerance grade of the reflector hole on the RB test block. The nominal dimensions of the conical hole 6-4 are 3mm in height and 3mm in bottom diameter. The nominal dimensions of the cylindrical hole 6-3 are 3mm in bottom diameter and 3mm in height. The height of the step 6-1 is 20mm and the width is 20mm. The length of the upper bottom of the reflector body 6 is 140mm, and the length of the lower bottom is 300mm.

[0027] The contrast reflector for ultrasonic flaw detection and evaluation of point defects in this embodiment is compared with the existing RB test block, and the process is as follows:

[0028] At present, ultrasonic flaw detection of welds in building steel structures uses the Φ3×40mm transverse hole reflector on the RB test block as the reference amplitude for defect assessment. Through practice and experimental comparison, it is found that for unfused point defects similar to cylindrical and conical defects in welds, the use of the Φ3×40mm transverse hole reflector on the RB test block as a reference for defect assessment has a large error. Use 2.5P13×1365°, 2.5P8×1265°, and 5P13×1365° probes to test the energy of cylindrical and cone reflected waves with a diameter and height of 3mm (the echo amplitude on the Φ3×40 reflector on the RB test block is used as the reference distance-amplitude curve, i.e., DAC curve). The test results are shown in Table 1, which shows the dB difference in echo amplitude between cylindrical holes and conical holes and Φ3×40 transverse holes for wafers of different areas:

[0029] Table 1

[0030]

[0031] From the test results in Table 1, we can see that the reflection amplitude of 3×3mm cylinder and 3×3mm cone is much lower than that of Φ3×40mm horizontal through hole. Such defects will be judged as defects that are allowed to exist. For example, according to the A-level inspection quantitative line DAC-10dB in Table 7.3.2 (see Table 2) of GB / T50621-2010 "Technical Standard for Field Inspection of Steel Structures", point defects with amplitudes lower than this line are allowed to exist. According to Table 1, the reflection amplitude of the defect with a hole depth of 20mm is lower than the quantitative line DAC-10dB. Such defects will be judged as defects that are allowed to exist. However, the defects of cylinders and cones are not smooth pore defects. The defects have sharp points (surfaces) and are dangerous point defects.

[0032] Table 2

[0033]

[0034] The reflector hole size of the comparative reflector for ultrasonic flaw detection and assessment of point defects in this embodiment is similar to the Φ3×40mm reflector hole cross-section on the RB test block. The comparative reflector of the utility model is designed as a 3×3mm cylinder (i.e., a cylindrical hole with a height and bottom radius of 3mm) and a 3×3mm cone (i.e., a conical hole with a height and bottom radius of 3mm), which is close to the current standard and similar to the geometric shape of the actual defect in flaw detection.

[0035] The method of using the contrast reflector for ultrasonic flaw detection and evaluation of point defects in this embodiment is as follows:

[0036] The distance-amplitude curve of the primary reflection wave is prepared as follows: Figure 3 As shown, the oblique probe is used to evaluate the top surface of the contrast reflector of the point defect in ultrasonic flaw detection in this embodiment ( Figure 3The reflected wave values ​​of 3×3mm cylinders and 3×3mm cones with different depths are found as the DAC reference line. The quantitative line and the evaluation line are determined by referring to the corresponding standards (such as Table 7.3.2 (i.e., Table 2 above) in GB / T50621-2010 Technical Standard for Field Inspection of Steel Structures). The distance-amplitude curve is shown in Figure 4 As shown, this curve reflects the echo energy of ultrasonic waves incident on cylindrical or conical reflectors at different distances. The scrap line is the baseline made by the reflector of the utility model. The evaluation line and the quantitative line are drawn with reference to the corresponding standards. The curve is used to detect point defects similar to cylindrical or conical defects. Since the energy difference between the defect and the geometric morphology of the reflector is eliminated, during actual flaw detection, the area (zone I, zone II, zone III) in the figure where the echo energy of the defect falls can be more accurately compared with the artificial reflector. If the defect reflection wave falls above the scrap line, it is more accurately explained that the defect scale is larger than the artificial cylindrical or conical reflector of the utility model.

Claims

1. A contrast reflector for ultrasonic flaw detection and evaluation of point defects, characterized in that: The invention comprises a plate-shaped reflector body (6), wherein the neutral surface of the reflector body (6) is in the shape of a trapezoid, and the two waists of the reflector body (6) are each provided with a plurality of steps (6-1), and a detection hole is provided on a surface of each step (6-1) parallel to the lower bottom of the reflector body (6); wherein the detection hole on one waist of the reflector body (6) is a conical hole (6-4), and the detection hole on the other waist of the reflector body (6) is a cylindrical hole (6-3).

2. The contrast reflector for ultrasonic flaw detection and evaluation of point defects according to claim 1, characterized in that: The number of steps (6-1) on each waist of the reflector body (6) is 3 to 6.

3. The contrast reflector for ultrasonic flaw detection and evaluation of point defects according to claim 1, characterized in that: The detection hole is arranged at the center of a surface on the step (6-1) that is parallel to the lower bottom of the reflector body (6).

4. The contrast reflector for ultrasonic flaw detection and evaluation of point defects according to claim 1, characterized in that: The tolerance grade of the conical hole (6-4) and the cylindrical hole (6-3) is the same as the tolerance grade of the reflector hole on the RB test block.

5. A contrast reflector for ultrasonic flaw detection and evaluation of point defects according to claim 1 or 4, characterized in that: The conical hole (6-4) has a height of 3 mm and a bottom diameter of 3 mm.

6. A contrast reflector for ultrasonic flaw detection and evaluation of point defects according to claim 1 or 4, characterized in that: The bottom diameter of the cylindrical hole (6-3) is 3 mm and the height is 3 mm.

7. The contrast reflector for ultrasonic flaw detection and evaluation of point defects according to claim 1, characterized in that: The height of the step (6-1) is 15~30mm.

8. The contrast reflector for ultrasonic flaw detection and evaluation of point defects according to claim 1, characterized in that: The width of the step (6-1) is 15~30mm.

9. The contrast reflector for ultrasonic flaw detection and evaluation of point defects according to claim 1, characterized in that: The length of the upper bottom of the reflector body (6) is 120-160 mm.

10. The contrast reflector for ultrasonic flaw detection and evaluation of point defects according to claim 1, characterized in that: The length of the lower bottom of the reflector body (6) is 280-320 mm.

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