CN114755300A - Defect positioning quantitative detection method based on ultrasonic nondestructive detection - Google Patents

Defect positioning quantitative detection method based on ultrasonic nondestructive detection Download PDF

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CN114755300A
CN114755300A CN202210396988.2A CN202210396988A CN114755300A CN 114755300 A CN114755300 A CN 114755300A CN 202210396988 A CN202210396988 A CN 202210396988A CN 114755300 A CN114755300 A CN 114755300A
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defect
scanning
signal
longitudinal wave
block
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赵纪元
王琛玮
王磊
韩瑞
颜江涛
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Xian Jiaotong University
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    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/043—Analysing solids in the interior, e.g. by shear waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
    • G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
    • G01N29/4436—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison with a reference signal

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Abstract

The invention discloses a defect positioning quantitative detection method based on ultrasonic nondestructive detection, which comprises the following steps: performing linear B scanning on a block to be tested to obtain B scanning signals comprising n A scanning signals; normalizing the non-defective reference signal and the B-scanning signal to obtain a defective echo signal; respectively extracting defect longitudinal wave echo time in each A-scanning signal from the defect echo signals; establishing a coordinate system by taking the first scanning position as an original point, the scanning direction as an x forward direction and the direction of the inside of the block to be tested, which is vertical to the surface of the block to be tested, as a y forward direction; and obtaining the position and the size of the defect according to the coordinates of the scanning points, the echo time of the longitudinal wave of the defect and the wave speed of the longitudinal wave. The position and the size of the defect can be directly output as a result of the method, the appearance of the defect is drawn in a coordinate system, and the output result is visual. According to the invention, the defect size can be obtained on the basis of the data of the linear B scanning, and compared with a mode of detecting the defects by C scanning, the detection efficiency is obviously improved.

Description

Defect positioning quantitative detection method based on ultrasonic nondestructive detection
Technical Field
The invention belongs to a defect detection technology of metal additive parts, and particularly relates to a defect positioning and quantitative detection method based on ultrasonic nondestructive detection.
Background
Under the traction of manufacturing requirements of large-scale, light-weight, integration, reliability and the like of parts in the aerospace field, metal additive manufacturing technology and equipment continuously mature, are subjected to pilot application in the aerospace field at present, and are obviously improved in manufacturing size and manufacturing efficiency compared with the traditional manufacturing process. The metal additive manufacturing method manufactures the solid part by melting and accumulating metal powder or wire layer by layer, greatly reduces the restriction of the structural complexity of the part on the manufacturing process, time and cost, even can manufacture the part which can not be processed by the conventional manufacturing technology, has strategic position in the aerospace field and has very wide application prospect. However, the metal additive manufacturing process is a very complex multi-physical field coupled strong non-equilibrium metallurgical process which simultaneously generates the interactive coupling effect of high energy beams and materials, the crystal growth under the condition of ultrahigh rapid solidification of a micro molten pool, the tissue evolution under the conditions of repeated cyclic heating and cooling, and the like, and has large temperature gradient and high solidification speed of the molten pool in the forming process, and metallurgical defects such as air holes, cracks and the like are easy to occur in a workpiece, thereby seriously affecting the mechanical property of the workpiece. At present, research on a defect detection technology for metal additive parts needs to be developed.
Ultrasonic inspection refers to a nondestructive inspection method for inspecting internal defects of a metal member by using ultrasonic waves. The ultrasonic wave is transmitted to the surface of the member by the coupling agent by using the transmitting probe, and the ultrasonic wave has different echo signals when meeting different interfaces when propagating in the member. The defects in the component can be detected by utilizing the time difference and signal attenuation condition of different reflected signals transmitted to the probe. The size, position and general nature of the defect can be judged according to the amplitude, propagation time and the like of the echo signal. Because the metal material is subjected to repeated cyclic heating and cooling in the additive manufacturing process, pores are easily generated in the workpiece, and therefore, the ultrasonic quantitative detection technology research on the pore defects in the additive workpiece needs to be carried out.
Chinese patent publication No. CN105973992A discloses "ultrasonic wavelet detection method for micro air hole defect of epoxy cast insulation member", which realizes quantitative detection of bottom surface defect of the workpiece, and obtains defect size by difference between bottom surface position and air hole position. But the method has better detection effect and detection precision on the bottom surface defects, and can realize defect positioning and size measurement of the defects for internal defects.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention aims to provide a defect positioning and quantitative detection method based on ultrasonic nondestructive detection, which can effectively improve the defect detection precision and improve the detection efficiency.
In order to achieve the purpose, the invention adopts the technical scheme that:
a defect positioning and quantitative detection method based on ultrasonic nondestructive detection comprises the following steps:
performing linear B scanning on a region to be detected of a block to be detected to obtain a B scanning signal S comprising n A scanning signals;
reference signal S without defectRNormalizing the B scanning signal S to obtain a defect echo signal S';
extracting the defect longitudinal wave echo time t in each A-scanning signal from the defect echo signal Si(ii) a i denotes a reference number of the sweep point;
establishing a coordinate system by taking the first scanning position as an original point, the scanning direction as an x forward direction and the direction of the inside of the block to be tested, which is vertical to the surface of the block to be tested, as a y forward direction;
and obtaining the position and the size of the defect according to the coordinates of the scanning points, the echo time of the longitudinal wave of the defect and the wave speed of the longitudinal wave.
A further development of the invention is that the longitudinal wave speed V is determined on a standard test block of the same material as the test block.
The invention is further improved in that A-scan experiment is carried out on the surface of a standard test block, and the arrival time T of secondary longitudinal wave and quartic longitudinal wave echo signals is extracted from the signals2、T4Based on the arrival time T of the secondary longitudinal wave and the fourth longitudinal wave echo signals2、T4And determining the wave speed of the longitudinal wave.
The invention is further improved in that the longitudinal wave velocity is calculated by the following formula:
Figure BDA0003599417340000021
wherein H is the thickness of the standard test block.
The invention is further improved in that the reference signal S is free of defectsRObtained by performing an a-scan at a defect-free location of the block to be tested.
The invention is further improved in that the defect-free reference signal S is usedRAnd B scanning the signal S to carry out normalization processing, and the specific process of obtaining the defect echo signal S' is as follows: subtracting the defect-free reference signal S from the B-scan signal SRAnd obtaining a defect echo signal S'.
The invention is further improved in that the center of the circle of the defect position is calculated by the following formula:
Figure BDA0003599417340000031
wherein i is 1 to n, D (x)D,yD) Is the center of the defect position.
A further development of the invention consists in that the defect size rDCalculated by the following formula:
Figure BDA0003599417340000032
compared with the prior art, the invention has the following technical effects:
the position and the size of the defect can be directly output as a result of the method, the appearance of the defect is drawn in a coordinate system, and the output result is visual. According to the invention, the defect size can be obtained on the basis of the data of the linear B scanning, and compared with a mode of detecting the defects by C scanning, the detection efficiency is obviously improved. The detection method is simple, and on the basis of B-scanning detection, calculation can be simplified by selecting not less than 3 representative positions and defect echo moments under extreme conditions. The data processing process is simple, the characteristic enhancement of the defect echo signal is not needed by a signal processing method, and only a reference signal is needed to be acquired in a non-defect area and subtracted from the original B-scanning signal.
Drawings
FIG. 1 is a flow chart of an implementation of an embodiment of the present invention;
FIG. 2 is a block diagram of a detection system in an embodiment of the invention;
FIG. 3 is an ultrasonic B-scan signal after normalization processing in an embodiment of the invention;
FIG. 4 shows the results of the treatment according to the invention.
FIG. 5 is a geometric relationship diagram of two scanning points and a defect.
Detailed Description
The method of the present invention is further described below with reference to the accompanying drawings and examples.
Referring to fig. 2, the detection system adopted by the invention comprises an industrial personal computer 1, a scanning device 2, a PLC 3, an ultrasonic transmitting device 4, a signal acquisition card 5 and an ultrasonic probe 6, wherein the scanning device 2, the PLC 3, the ultrasonic transmitting device 4 and the signal acquisition card 5 are all connected with the industrial personal computer 1, the scanning device 2 is connected with the ultrasonic probe 6, the ultrasonic transmitting device 4 is also connected with the ultrasonic probe 6, and the ultrasonic probe 6 is used for testing a test block 7 to be tested.
The invention discloses an ultrasonic quantitative detection method for internal pore defects of a workpiece, which comprises the following steps:
step 1: measuring the longitudinal wave velocity V on a standard test block made of the same material as the block to be tested; the method specifically comprises the following steps:
step 1.1, performing A-scan experiment on the surface of a standard test block with the thickness of H through an ultrasonic probe 6, and extracting the arrival time T of longitudinal wave echo signals such as secondary longitudinal wave, fourth longitudinal wave and the like from the signals2、T4Measuring the thickness H of the standard test block;
step 1.2, determining the longitudinal wave velocity
Figure BDA0003599417340000041
Step 2: a scanning is carried out at the defect-free position of the block to be tested to obtain a defect-free reference signal SR；
And step 3: smearing a coupling agent (a type is a Honda CG-98 ultrasonic coupling agent) on an area to be detected of a block to be detected, and performing linear B scanning to obtain a B scanning signal S comprising n A scanning signals;
and 4, step 4: normalization treatment: subtracting the defect-free reference signal S from the B-scan signal SREnhancing the defect echo signal, and inhibiting the bottom echo of the longitudinal wave to obtain a defect echo signal S';
and 5: extracting the defect longitudinal wave echo time t in each A-scanning signal from the defect echo signal Si(ii) a i denotes a reference number of the sweep point;
step 6: establishing a coordinate system by taking the first scanning position as an original point, the scanning direction as the positive x direction and the direction vertical to the upper surface of the block to be tested as the positive y direction, and setting the coordinate of the ith scanning point as (x)i,yi)；
And 7: and solving the position and the size of the defect according to the coordinate of the scanning point, the echo time of the longitudinal wave of the defect and the wave speed of the longitudinal wave: the method comprises the following specific steps:
step 7.1, constructing an equation set
Figure BDA0003599417340000051
Substituting the wave velocity V of the longitudinal wave into the coordinate (x) of the scanning pointi,yi) Time t of longitudinal wave echo of defectiCalculating the center position D (x) of the defect circleD,yD) (ii) a i is 1 to n.
Step 7.2, construct equation
Figure BDA0003599417340000052
Calculating the defect radius rD。
The detection principle of the invention is as follows:
assuming that the defect is a point (ignoring shape and size) which completely reflects the ultrasonic wave, when the ultrasonic wave propagates to the defect, because the probe has both excitation and receiving functions, the defect echo signal collected by the probe is the ultrasonic signal which returns along the original path of the ultrasonic wave propagation path, so that the product of the propagation time t and the wave speed V obtained from the ultrasonic signal is twice the distance from the probe to the defect. When the defect position is unknown, the position of the probe is taken as the center of a circle, the distance from the probe to the defect is taken as the radius to draw a circle, and the point on the circle is the position of the defect (reflection point) (the accurate defect position cannot be obtained from a single signal).
When the defect is an air hole, the section of the defect is circular, and because the ultrasonic wave propagates along the shortest path in the medium, a connecting line from the probe to the reflection point of the defect passes through the center of the defect (namely, the three points of the probe, the reflection point and the center of the defect are on the same straight line).
When there are 2 scanning points (probe positions), as shown in FIG. 5, let A, B be a scanning point, and a dashed line indicates [ < D > as a defect. As indicated by the drawing of a circle having the scanning point a as the center, and a half of the product of the defect echo time and the wave velocity (AM length) as the radius, a defect reflective point was formed as indicated by the curve a. M is a reflection point corresponding to the scanning point A, so that M is not only on ^ A, but also on ^ D, and three points of AMD are on a straight line. Similarly, B is the second scanning point, N is the corresponding reflection point, and the BND three points are on a straight line.
If M is equal to D, then DM is equal to DN, and so is equal to AD-BD, then | MA-NB |. From the above reasoning, when defect | _ D is unknown, the relationship between A, B, M, N indicates that a hyperbola can be drawn with | MA-NB | as a real axis and the center D of the defect located on the hyperbola as shown by the dashed line segment in FIG. 5 with A, B as a focus.
In order to obtain the position of the center of the defect, only three times of scanning is needed, and two hyperbolas are drawn. However, in consideration of the detection accuracy, it is necessary to plot as many hyperbolas as possible (corresponding to the equation set in step 7.1), the intersection point of which is the center of the defect, and after the center of the defect is found, the radius r of the defect is AD-AM BD-BN.
Example 1
The embodiment provides a defect positioning quantitative detection method based on ultrasonic nondestructive testing, and the specific implementation process is shown in fig. 1, and the method comprises the following steps:
1. preparing a standard test block and a defective test block;
two ER2319 aluminum alloy test blocks are prepared by an electric arc welding additive manufacturing technology, the size is 100 multiplied by 10mm, one test block without defects is marked as a standard test block, the other test block is marked as a defect test block, the side face machining radius is 1mm, and a transverse through hole with the depth of 5mm (circle center position) is marked as a defect.
2. Measuring the wave speed of longitudinal waves;
and (3) smearing a coupling agent on the surface of the standard test block, arranging an ultrasonic probe, detecting and acquiring an A-scanning signal. In the signal, the primary longitudinal wave bottom echo appears at 3.4 mu s, the secondary longitudinal wave bottom echo appears at 6.9 mu s, and the longitudinal wave propagation speed is 5840m/s by combining the thickness of a standard test block of 10 mm.
3. Acquiring defect-free reference signals
Performing A-scan experiment at the defect-free position of the defect test block, and performing time domain averaging on the signals after 16 repeated experiments to reduce errors to obtain a reference signal SR. In order to pursue the accuracy of the detection result, the scanning data is selected as much as possible.
4. Acquiring an original ultrasonic signal;
and (3) placing the defect test block on a scanning device, smearing a coupling agent on the area to be detected, and fixing the ultrasonic probe on the scanning device. Scanning parameters are set in a computer: the number of scanning points is 5, the scanning step length is 1mm, the sampling frequency is 20MHz, the time domain average frequency is 16 times, the signal length is 160 points (8 mu s), and the normalized signal is shown in figure 3. The positions of occurrence of longitudinal wave echoes of the defects are 58, 52, 47, 42 and 37, and the corresponding longitudinal wave echo time is 2.9 mus, 2.6 mus, 2.3 mus, 2.1us and 1.85 mus.
5. Substituting the equation for calculation, and solving the defect position;
substituting the coordinates of the scanning points, the echo time and the longitudinal wave velocity into an equation set
Figure BDA0003599417340000071
Wherein i is 1,2,3, 4.
And (3) respectively drawing hyperbolas by taking the first scanned position as a coordinate raw snack according to the 4 equations as shown in fig. 4, marking 5 scanned point positions on the x axis, and taking the intersection point of the four hyperbolas as the center position D of the defect circle (8.008, 5.006).
6. Calculating by substituting equation to solve defect radius
Figure BDA0003599417340000072
5 defect radius values were obtained, and after averaging, the defect radius was obtained at 1.0112mm, which was consistent with the defect size.

Claims (8)

1. A defect positioning quantitative detection method based on ultrasonic nondestructive detection is characterized by comprising the following steps:
performing linear B scanning on a region to be detected of a block to be detected to obtain a B scanning signal S comprising n A scanning signals;
reference signal S without defectRNormalizing the B scanning signal S to obtain a defect echo signal S';
extracting the defect longitudinal wave echo time t in each A-scanning signal from the defect echo signal Si(ii) a i denotes a reference number of the scanning point;
establishing a coordinate system by taking the first scanning position as an original point, the scanning direction as an x forward direction and the direction of the inside of the block to be tested, which is vertical to the surface of the block to be tested, as a y forward direction;
and obtaining the position and the size of the defect according to the coordinates of the scanning points, the echo time of the longitudinal wave of the defect and the wave speed of the longitudinal wave.
2. The method for locating and quantitatively detecting the defects based on the ultrasonic nondestructive testing of claim 1 is characterized in that the longitudinal wave velocity V is obtained by measuring on a standard test block made of the same material as the block to be tested.
3. The method of claim 2, wherein the A-scan test is performed on the surface of a standard test block, and the arrival time T of the secondary longitudinal wave echo signal and the arrival time T of the fourth longitudinal wave echo signal are extracted from the signals2、T4Based on the arrival time T of the secondary longitudinal wave and the fourth longitudinal wave echo signals2、T4And determining the wave speed of the longitudinal wave.
4. The method of claim 3, wherein the longitudinal wave velocity is calculated by the following formula:
Figure FDA0003599417330000011
wherein H is the thickness of the standard test block.
5. The method for defect localization and quantitative detection based on ultrasonic nondestructive detection as claimed in claim 1, wherein the reference signal S without defects isRObtained by performing an a-scan at a defect-free location of the block to be tested.
6. The method for locating and quantitatively detecting the defects based on the ultrasonic nondestructive testing of claim 1 is characterized in that a defect-free reference signal S is usedRAnd B scanning the signal S to carry out normalization processing, and the specific process of obtaining the defect echo signal S' is as follows: subtracting the defect-free reference signal S from the B-scan signal SRAnd obtaining a defect echo signal S'.
7. The method for locating and quantitatively detecting the defects based on the ultrasonic nondestructive testing as claimed in claim 1, wherein the center of the circle of the defect position is calculated by the following formula:
Figure FDA0003599417330000021
wherein i is 1 to n, D (x)D,yD) Is the center of the defect.
8. A hyper-base as in claim 7The method for locating and quantitatively detecting the defect of sound nondestructive detection is characterized in that the defect size rDCalculated by the following formula:
Figure FDA0003599417330000022
CN202210396988.2A 2022-04-15 2022-04-15 Defect positioning quantitative detection method based on ultrasonic nondestructive detection Pending CN114755300A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115343360A (en) * 2022-08-10 2022-11-15 西安交通大学 Laser ultrasonic layered self-adaptive mode scanning method and system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115343360A (en) * 2022-08-10 2022-11-15 西安交通大学 Laser ultrasonic layered self-adaptive mode scanning method and system
CN115343360B (en) * 2022-08-10 2024-05-17 西安交通大学 Laser ultrasonic layering self-adaptive mode scanning method and system

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