CN110687198A - Method for detecting welding seam defect types of friction stir welding by ultrasonic phased array - Google Patents

Method for detecting welding seam defect types of friction stir welding by ultrasonic phased array Download PDF

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Publication number
CN110687198A
CN110687198A CN201910961250.4A CN201910961250A CN110687198A CN 110687198 A CN110687198 A CN 110687198A CN 201910961250 A CN201910961250 A CN 201910961250A CN 110687198 A CN110687198 A CN 110687198A
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phased array
ultrasonic phased
detecting
friction stir
detection
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李成军
杨秋萍
林刚
徐平华
乐洪甜
程欣
程炜
刘钺
张量
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Inspection & Research Institute Of Boiler & Pressure Vessel Of Jiangxi Province
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Inspection & Research Institute Of Boiler & Pressure Vessel Of Jiangxi Province
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    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/26—Scanned objects
    • G01N2291/267—Welds
    • G01N2291/2675—Seam, butt welding

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  • Acoustics & Sound (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
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  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

Abstract

The invention provides a method for detecting the type of a friction stir welding seam defect by using an ultrasonic phased array, and belongs to the technical field of nondestructive detection of a welding joint. The method comprises the steps of using an aluminum alloy as a raw material, obtaining butt welding seams by using FSW, detecting the shapes of the interfaces of defects in the butt welding seams and the defects of the tunnel holes in different shapes, carrying out repeated point research on the characteristics of phased array sector scanning modes in different directions of the interfaces of the tunnel holes by using an ultrasonic phased array, and finally identifying the different shapes of the defects of the tunnel holes and the unsoldered parts by combining texture analysis. The invention has the advantages that: (1) the detection is convenient and easy to operate. (2) The detection efficiency is high, and the reliability is strong. In conclusion, the ultrasonic phased array technology has obvious advantages for FSW weld joint detection, is accurate in tunnel hole positioning, and has good detectable rate even if the orientation of a defect interface is complex in the aspect of detection of fine size defects.

Description

Method for detecting welding seam defect types of friction stir welding by ultrasonic phased array
Technical Field
The invention belongs to the technical field of nondestructive testing of welding joints, and particularly relates to a method for detecting the type of a friction stir welding seam defect by using an ultrasonic phased array.
Background
Since the advent of the Friction Stir Welding (FSW) technology in the early 90 s of the 20 th century, it was considered to be the most attractive Welding method after self-laser Welding. The appearance of the aluminum alloy welding machine enables the connection technology of non-ferrous metals such as aluminum alloy and the like to be changed greatly, and some high-strength aluminum alloy materials which are considered to be unweldable in the past can be welded by friction stir welding basically, so that a plurality of successful application paradigms are shown in the fields of aerospace, ships, high-speed railway train manufacturing and the like.
In practical application, due to the influence of factors such as welding process parameter deviation, clamping conditions, material surface conditions and operators, the friction stir welding workpiece may have defects, so that the performance of the joint is influenced, and the friction stir welding defects have the characteristics of close attachment, fineness, complex orientation and the like compared with the conventional fusion welding defects, so that the detection difficulty is increased, the popularization and the application of the friction stir welding workpiece are influenced to a certain extent, and the friction stir welding workpiece has great practical significance on the high efficiency, the accuracy and the convenience of the defect detection. At present, nondestructive detection technologies for friction stir welding weld defects mainly include X-ray and ultrasonic detection, X-ray images are clear and can be stored for a long time, but detection sensitivity is relatively low, ultrasonic detection applicability is high, detection sensitivity is high, ultrasonic detection research is mainly focused on defects with regular incidence surfaces at present, research on defect interfaces with variable curvature and variable orientation is few, interface morphology is easy to change due to plastic metal flowing caused by stirring in an FSW process, different from detection of straight interfaces, ultrasonic focusing and scattering characteristics are enhanced by curved interfaces, defect detection is difficult, an oblique incidence mode is usually adopted for incomplete penetration defect detection, and detection angles are difficult to select due to orientation uncertainty.
However, the ultrasonic phased array technology can realize focusing and deflection of an acoustic beam by controlling the time difference of wafer excitation, ultrasonic energy is concentrated, and a single probe can be used for scanning in multiple angles under the condition of unchanged position, many researchers use the ultrasonic phased array detection method for detecting FSW defects, and find that the phased array has good detectable rate and accurate positioning capability on defects with complex orientation, but the defect type is difficult to judge accurately, so that many researchers combine the image processing technology and the ultrasonic phased array, and realize feature extraction and identification of different defect images by methods such as threshold segmentation, boundary extraction, texture analysis and the like, but the research method is rare in the field of FSW, and the correlation between the defect interface form and the interface texture is strong.
Disclosure of Invention
The invention aims to provide a method for detecting the type of a friction stir welding seam defect by using an ultrasonic phased array. The method can detect the type and the size of the defect, extract the characteristics of the defect by adopting a gray level histogram and a gray level co-occurrence matrix algorithm in a texture analysis method, and identify the defect form through the parameter analysis of the gray level co-occurrence matrix.
The method for identifying and separating the incomplete penetration and the tunnel hole signals by utilizing the advantages of the ultrasonic phased array is obtained by analyzing the incomplete penetration and the tunnel hole signals in the phased array sector scanning mode in different directions. Firstly, performing FSW butt joint on aluminum alloy plates to obtain butt weld joints, adopting an ultrasonic phased array sector scanning mode to perform incomplete penetration and tunnel holes in different forms in the weld joints, and analyzing phased array sector scanning images in different directions to obtain a method for identifying and separating signals of the incomplete penetration and the tunnel holes. And the defects of different interface forms are distinguished by combining the detection image and the signal of the fan-shaped scanning mode and the texture analysis of the detection image.
The invention is realized by the following technical scheme:
the method comprises the steps of using an aluminum alloy as a raw material, obtaining butt welding seams by using FSW, researching the influence of interface forms on defects by means of ultrasonic phased arrays on the defects, researching the characteristics of phased array sector scanning modes of different directions of a tunnel hole interface in a repeated mode, and finally identifying different forms of the defects of the unwelded and the tunnel holes by combining texture analysis.
The preparation process of the butt weld comprises the following steps: the aluminum alloy butt-joint plate is processed before welding, and then the aluminum alloy plate with the inclination angle is subjected to FSW butt joint to prepare a butt joint seam welding test plate to be detected. The preparation method comprises the following steps: firstly, milling the butt joint surface of the aluminum alloy plate into a form with an inclination angle, wherein the inclination angle is greater than 0 degree and less than or equal to 90 degrees. And then selecting an FSW welding process, wherein the rotating speed is 300-1500 r/min, and the welding speed is 23.5-150 mm/min.
The preparation and the filling of the aluminum sheath comprise the following steps: the ultrasonic phased array mainly detects incomplete penetration and tunnel holes of a welding test plate, and distinguishes different interface form defects by combining detection images and signals of different scanning modes and texture analysis of the detection images.
Further, the lack of penetration can be vertical lack of penetration, straight lack of penetration, and bent lack of penetration; the tunnel hole may be a curved unwelded tunnel hole, a straight unwelded tunnel hole.
Further, the scanning mode is linear scanning and sector scanning.
Further, texture analysis is to extract and analyze texture features of a defect image obtained by phased array fan scanning detection to obtain image feature values (angle second order distance, entropy value, contrast and correlation).
The invention has the advantages that:
1. the detection is convenient and easy to operate. The ultrasonic phased array detection can realize the flaw detection of test pieces with different thicknesses and defects in different directions.
2. The detection efficiency is high, and the reliability is strong. The ultrasonic phased array detection system is carried out in an electronic flaw detection mode, so that scanning efficiency is improved, and reliability of the ultrasonic phased array detection system is obviously enhanced.
In conclusion, the ultrasonic phased array technology has obvious advantages for FSW weld joint detection, is accurate in tunnel hole positioning, and has good detectable rate even if the orientation of a defect interface is complex in the aspect of detection of fine size defects.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
FIG. 1 is a schematic diagram of FSW butt seam test plate prepared according to the present invention;
FIG. 2 is a macroscopic view of example 1 without penetration of the weld at different lengths;
wherein, the length of the graph (a) is 1.0mm, the length of the graph (b) is 0.85mm, and the length of the graph (c) is 0.38 mm.
FIG. 3 is the detection image and signal of the backward ultrasonic fan scan in example 1;
in the drawings, (a), (b), and (c) correspond to (a), (b), and (c) in fig. 2, respectively.
FIG. 4 is the gray level co-occurrence matrix results of different length incomplete penetration test images of example 1;
in the figure, (a) represents an angular second distance value comparison figure, (b) represents an entropy value comparison figure, (c) represents a contrast figure of contrast, and (d) represents a contrast figure of correlation.
FIG. 5 is a macroscopic view of a tunnel hole in accordance with example 2;
in the figure, 2 indicates the direction 2 and 3 indicates the direction 3.
FIG. 6 is the detection images and signals of the ultrasonic sector scanning of the tunnel hole in different directions in example 2;
in the figure, (a) shows a detection image in the direction 2, and (b) shows a detection image in the direction 3.
FIG. 7 is a gray level co-occurrence matrix result of different tunnel hole interface detection images in example 2.
Detailed Description
Example 1
Three vertical unsoldered butt seam specimens of different lengths were prepared. The method is characterized in that 2A14 aluminum alloy plates with the sizes of 200mm multiplied by 150mm multiplied by 8mm are selected to manufacture butt-joint welding seams, the stirring head is made of H13 steel, the specific size parameters are shaft shoulder diameter phi 26mm, the lengths of the stirring pins are three types, namely 5.5mm, 5.7mm and 6.2mm, the surface threads of the stirring pins are left-handed threads, the rotation speed of the welding parameters is 950r/min, the welding speed is 75mm/min, and the inclination angle of the stirring head is 2 degrees. The inclined angle of the test board butt joint surface is formed by wire cutting and milling machine processing, and the inclined angle of 90 degrees is selected as the vertical butt joint surface in the embodiment. The form of the butt surface and the insertion position of the stirring pin are shown in FIG. 1.
In order to research the influence of vertical incomplete penetration defects with different lengths on detection, stirring heads with left-handed threaded stirring needles (5.5mm, 5.7mm and 6.2mm) with different lengths are adopted to weld the vertical butt joint test plates to obtain welding samples with different lengths and incomplete penetration, and the labeled sample numbers are C respectively1、C2And C3. And (3) using a 5MHz phased array probe with 16 wafers to perform sector scanning on the incomplete penetration and the tunnel holes with different forms, analyzing the influence of the interface length on detection, and distinguishing the tunnel holes with different forms and the incomplete penetration with different forms. And (3) extracting and analyzing the texture features of the typical defect image on the basis of the gray level co-occurrence matrix to obtain the texture features of the image, and extracting 4 characteristic values (angle second-order distance, entropy value, contrast and correlation) in 4 generation directions (0 degrees, 45 degrees, 90 degrees and 135 degrees) of the image.
The results show that: (1) c1、C2And C3The corresponding vertical lack of penetration lengths were 1.0mm, 0.85mm, 0.38mm, respectively (results are shown in FIG. 2); the detection signals of the corresponding receding sides were 83.4%, 73.2%, and 24.3%, respectively (the results are shown in fig. 3). (2) During gray level co-occurrence matrix analysis, for vertical non-penetration interfaces with different lengths, the angular second moment and the non-penetration length are in positive correlation, entropy value is obvious for long non-penetration feedback, contrast and correlation are obvious for short non-penetration feedback, comprehensive analysis can be carried out, different lengths can be identified, and the length difference can be judged to a certain extent (the result is shown in fig. 4).
Example 2
The same materials and FSW process as in example 1 were used, and a welded defect test plate was obtained by FSW butt joint using a 45-degree-of-inclination processed plate and a non-threaded pin. Since the butt surface of the test panels was varied in inclination angle and pin length as compared to example 1, the butt weld was varied in the non-penetration state. Since the plastic flow effect of the non-threaded stirring pin is low, and the prepared non-penetration defect is a straight interface, the backward side molding metal is not enough to fill the instantaneous cavity of the forward side in the welding process, and a tunnel hole appears on the forward side (the side with the welding direction same as the rotation direction of the stirring head) (as shown in fig. 5). Meanwhile, the same ultrasonic phased array as that in the embodiment 1 is adopted to carry out phased array sector scanning mode characteristics in different directions, and finally different forms of tunnel hole defects are identified by combining texture analysis.
The results show that: the tunnel hole is tested for inconsistencies in ultrasonic sector sweep signal strength in the 2 and 3 directions (as shown in figure 6). Meanwhile, for the tunnel hole interfaces with two forms, the angle second moment and the contrast are taken as main components, and entropy value and correlation are taken as supplements, so that the two interface forms can be effectively distinguished (as shown in fig. 7).
Without being limited thereto, any changes or substitutions that are not thought of through the inventive work should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope defined by the claims.

Claims (9)

1. A detection method for detecting the type of a friction stir welding seam defect by an ultrasonic phased array is characterized by comprising the following steps: the method comprises the steps of taking aluminum alloy as a raw material, preparing a butt weld test plate by using FSW (free space beam), detecting incomplete penetration and tunnel hole weld defects by using an ultrasonic phased array, and distinguishing different interface morphological defects by combining detection images and signals of a linear scanning/sector scanning mode and texture analysis of the detection images so as to detect a defect interface.
2. The method for detecting the defect type of the friction stir welding seam by the ultrasonic phased array according to claim 1, characterized by comprising the following steps: the aluminum alloy butt-joint plate is processed before welding, and then the aluminum alloy plate with the inclination angle is subjected to FSW butt joint to prepare a butt joint seam welding test plate to be detected.
3. The method for detecting the defect type of the friction stir welding seam by the ultrasonic phased array according to claim 1, characterized by comprising the following steps: the ultrasonic phased array mainly detects incomplete penetration and tunnel holes of a welding test plate, and distinguishes different interface form defects by combining detection images and signals obtained in different scanning modes and texture analysis of the detection images.
4. The method for detecting the defect type of the friction stir welding seam by the ultrasonic phased array according to claim 2, characterized by comprising the following steps: and milling the butt joint surface of the butt joint welding test plate to be detected into a form with an inclination angle, wherein the inclination angle is greater than 0 degree and less than or equal to 90 degrees.
5. The method for detecting the defect type of the friction stir welding seam by the ultrasonic phased array according to claim 2, characterized by comprising the following steps: the FSW process has the rotating speed of 300-1500 r/min and the welding speed of 23.5-150 mm/min.
6. The method for detecting the defect type of the friction stir welding seam by the ultrasonic phased array according to claim 2, characterized by comprising the following steps: the aluminum alloy is from 1 series to 7 series aluminum alloy, the thickness is 1-10 mm, the material of the stirring head is H13 steel, high temperature alloy, directional solidification and tungsten-rhenium alloy, and the length of the stirring needle is smaller than the thickness of the plate.
7. The method for detecting the defect type of the friction stir welding seam by the ultrasonic phased array according to claim 3, characterized by comprising the following steps: the lack of penetration is vertical lack of penetration, straight lack of penetration and bending lack of penetration; the tunnel holes are bent non-welded through tunnel holes and straight non-welded through tunnel holes.
8. The method for detecting the defect type of the friction stir welding seam by the ultrasonic phased array according to claim 3, characterized by comprising the following steps: the scanning modes are linear scanning and sector scanning.
9. The method for detecting the defect type of the friction stir welding seam by the ultrasonic phased array according to claim 3, characterized by comprising the following steps: the texture analysis is that the defect image obtained by phased array sector scanning detection is subjected to texture feature extraction and analysis to obtain an image feature value, and the image feature value comprises: angular second order distance, entropy value, contrast, correlation.
CN201910961250.4A 2019-10-11 2019-10-11 Method for detecting welding seam defect types of friction stir welding by ultrasonic phased array Pending CN110687198A (en)

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
CN111983030A (en) * 2020-08-20 2020-11-24 南京中车浦镇城轨车辆有限责任公司 Friction welding seam defect quantitative detection method and system based on ultrasonic phased array

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CN106353410A (en) * 2016-08-22 2017-01-25 南京越辰智能科技有限公司 Ultrasonic phased array imaging detection device for aluminum alloy friction stir weldment

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Publication number Priority date Publication date Assignee Title
CN103268491A (en) * 2013-05-30 2013-08-28 哈尔滨工业大学 Weld defect ultrasound phased array sector scanned image feature extraction method
CN106353410A (en) * 2016-08-22 2017-01-25 南京越辰智能科技有限公司 Ultrasonic phased array imaging detection device for aluminum alloy friction stir weldment

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胡博文: "铝合金搅拌摩擦焊缺陷超声相控阵检测及其图像特征识别", 《中国优秀博硕士学位论文全文数据库工程科技I辑》 *

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111983030A (en) * 2020-08-20 2020-11-24 南京中车浦镇城轨车辆有限责任公司 Friction welding seam defect quantitative detection method and system based on ultrasonic phased array

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Application publication date: 20200114