WO2019091029A1 - Phased array ultrasonic testing method for weld seam of housing welded by using aluminum alloy - Google Patents

Abstract

A phased array ultrasonic testing method for a weld seam of a housing welded by using aluminum alloy, which relates to the technical field of weld seams of housings welded by using aluminum alloy and particularly, to quality detection technologies of the weld seams. A linear scanning check is carried out along a weld seam direction of a straight tube by using an phased array probe perpendicular to the weld seam. The present invention provides an optimized testing method for selecting parameters of a corresponding phased array probe according to the maximum thickness of a detected welded tube, thereby achieving the objectives of convenience, rapidness and accuracy and the objective for facilitating subsequent analysis.

Description

Phased array ultrasonic testing method for welded joint of aluminum alloy welded shell Technical field

The invention relates to the technical field of welding of aluminum alloy welded casings, in particular to the quality inspection technology of weld seams.

Background technique

In industrial production, after the material is formed by longitudinal joints, circumferential seams or spiral seams to form the pipe required for design, it is necessary to perform ultrasonic non-destructive testing on the weld of the pipe in time, in order to meet the quality requirements before entering the next process, such as If the inspection does not meet the quality requirements, it must be reworked.

At present, the actual method of inspecting the weld is to place the work on a workbench that can control its movement, and the inspection worker holds a common ultrasonic instrument, and the inspection workman observes the dynamic waveform information through the display screen on the ultrasonic system, if found on it. When the information that is abnormal (ie, does not meet the quality requirements) is reflected, the mark is marked there. Due to the long time of ordinary ultrasonic testing, the influence of human factors is large, and the use of the couplant remover is time consuming and laborious. For example, a 18-meter spiral welded pipe with a weld length of 40 meters and two ordinary ultrasonic sensors are tested at the same time, each requiring 90 minutes. Since ordinary ultrasound is a zigzag scan, the risk of missed detection caused by human factors is very large, and the waveform cannot be stored, and it is not possible to perform a later analysis. In addition, due to the influence of the ordinary ultrasonic system or X-Ray detection on the position of the weld, some defects cannot be detected and missed.

Phased Array Ultrasonic Testing (PAUT) is a method of applying different time delays (or voltages) to each unit of an array probe when transmitting or receiving ultrasonic waves according to a set focusing law, and detecting the movement of the sound beam by beamforming. Ultrasonic inspection imaging technology for functions such as deflection and focusing.

The phased array ultrasound host probe consists of 64 piezoelectric wafers. Each piezoelectric wafer forms a transmitting/receiving array element, and then under the excitation of the transmitting circuit, the phase difference formed by the phase relationship of each transmitting or receiving ultrasonic wave reaching a point in the object is changed by pulse delay to achieve the deflection of the beam. Focus to achieve detection.

However, due to the different thickness of the aluminum alloy welded casing in the actual production process, the ordinary phased array ultrasonic testing method can not achieve the intended purpose, and also causes missed or over-detected.

Summary of the invention

The object of the present invention is to provide a phased array ultrasonic testing method for a weld of an aluminum alloy welded casing which is convenient, fast, accurate and convenient for later analysis.

The invention adopts a phased array probe perpendicular to the weld seam and performs a linear scan along the straight pipe weld direction; the phased array probe is a phased array probe conforming to JB/T 11731.

The parameters of the phased array probe are shown in the following table:

Through repeated research, demonstration and comparison, the present invention proposes a preferred detection scheme for selecting the parameters of the corresponding phased array probe according to the maximum thickness of the welded pipe to be inspected, which is convenient, fast and accurate, and is convenient for later analysis. purpose.

In practical applications, the above phased array ultrasonic method of the present invention can be used to detect the workpiece. For example, a 18-meter spiral welded pipe with a weld length of 40 meters can be completed by using the above phased array ultrasonic method of the present invention for one person for 30 minutes. Since phased array ultrasound is a sector scan, the influence of human factors is small, safe and environmentally friendly, high efficiency, high accuracy, and storable. This saves time and precision and ensures the quality of the product. Then, the defects found are re-examined by ordinary ultrasound and manual dissection.

Advantages of the invention:

1. No ionizing radiation, using water as a coupling agent, harmless to the human body and the environment, is a green detection method.

2. It is sensitive to area defects such as unfused and cracked. Compared with common ultrasonic testing and radiographic detection, the defect detection rate is higher.

3, the detection efficiency can reach 3 to 5 times of ordinary ultrasonic detection and radiation detection; it can also cross-work, there is no specific requirement for environment and time; at the same time, all inspection records are digitally stored for easy traceability and preservation.

Further, the present invention uses two phased array probes for synchronous linear scanning, and two phased array probes are respectively disposed on the same side of the welded pipe weld, and on both sides of the straight pipe weld. Use a mechanism similar to one-dimensional line scanning, so that only one scan can simultaneously obtain the data scanned on both sides of the weld.

It has been studied that the speed of linear scanning is different with respect to different welds of different aluminum alloy casings:

When the weld bead is a longitudinal slit, the linear scanning speed is not more than 100 mm/s along the axis of the pipe. Improve the efficiency of testing and save time for testing.

When the weld bead is a spiral weld, the speed of the straight scan is 1 to 2 m/min along the axial direction of the straight pipe. This not only ensures the work efficiency, but also obtains a stable data for analysis and judgment.

When the weld bead is a circumferential seam, the speed of the linear scanning is 1 to 2 m/min along the direction of the weld of the steel pipe. While ensuring work efficiency, a stable data can be obtained for analysis and judgment.

The 10 ° C ~ 35 ° C water with pure, no bubbles and impurities is used as the coupling agent of the phased array probe. It is coupled with water and has no pollution to the environment. Under the water temperature of 10 °C ~ 35 °C, water transmits better to sound waves, and the obtained data is more accurate.

Detailed ways

First, the detection of pre-processing:

1. Venue:

The test environment should not be carried out at locations that affect the normal operation of ultrasonic instruments and auxiliary electrical equipment, such as strong magnetic, vibration, high frequency, large dust, corrosive gases and noisy locations.

2, temperature and humidity:

The temperature and humidity of the working point should be controlled within the range allowed by the testing equipment, auxiliary electrical equipment and materials.

3. For the movement and coupling of the probe, the surface of the workpiece to be inspected is free from dust, impurities and pollutants, and the surface roughness is ≤ Ra6.3.

Place the workpiece on a console that controls the constant velocity and moves axially along the straight tube. The control movement speed of this example is 80 mm/s.

Second, the detection host:

Use OLYMPUS OmniScan MX2 phased array ultrasound system; instrument data acquisition and scanning device mobile synchronization, with storage and resolution.

Third, the coupling agent:

Use 10 ° C ~ 35 ° C water with pure, no bubbles and impurities.

Fourth, the scanning steps:

According to the thickness of the workpiece, the shape and size of the weld profile, the corresponding standard calibration block and the comparison verification test block are selected for verification.

1. Sensitivity adjustment: The amplitude of the φ2 transverse through hole with a depth of 10 mm on the calibration test block is calibrated to 80%, and the sensitivity calibration is completed. This process uses the above coupling agent.

2, TCG curve production: select the TCG production module on the phased array ultrasound system, adjust the amplitude of the φ2 hole at the depth of 10mm to 80%, adjust the green line to the two red dotted boxes, click OK, add the next One point, adjust the amplitude of the φ2 transverse through hole at depth 20mm to 80%, and adjust the inner green line to the two red dotted lines. Add the first point, click OK, and the TCG curve is completed. The maximum depth of the transverse hole is greater than 2.2 times the thickness of the plate.

3. Probe selection:

The phased array probe is JB/T 11731 compliant. A phased array probe consists of an array of multiple wafers.

The selected phased array probe conforms to JB/T 11731, and the phased array probe consists of multiple wafers. The parameters of the phased array probe are shown in the following table:

In the above table, the wafer pitch refers to the distance between the same side or center of two adjacent wafers.

The deflection direction aperture size refers to the size of a set of wafers used by each probe.

The following is an example of longitudinal seam welding, and the maximum thickness of the straight pipe is 6 mm ≤ T < 15 mm.

Two phased array probes are used for synchronous linear scanning. The two phased array probes are respectively arranged on the same side of the straight pipe weld and on both sides of the weld.

4. Compensation: According to the product quality assurance system, add 6dB compensation to measure. Click the UT button on the phased array ultrasound system to set it. Select Advanced, click Reference dB, click gain +6 to complete the setting of gain.

The time gain correction is to gain correction of the echoes of the same size reflector at different sound paths to achieve the same amplitude.

5, scanning surface preparation:

The scan surface should be marked on the workpiece scan surface before the scan. The mark content includes at least the scan start point and the scan direction.

6, the operation steps:

Two phased array probes are used for synchronous linear scanning. The two phased array probes are respectively arranged on the same side of the steel pipe weld and on both sides of the steel pipe weld. The two phased array probe wafer arrays are oriented perpendicular to the probe's direction of movement or at a stable angle.

The leading edge of the probe leaves a certain distance from the center of the weld and translates along the axis of the weld to obtain information on the weld within the coverage of the sound beam.

The above coupling agent is continuously supplied by a water pump during the scanning process.

After scanning beyond the starting point, stop scanning and press the Save button.

7, measurement:

Store the memory card in the instrument on the computer and open it with OmniPC-4.4R3 software. Combine the B-type display, C-type display, S-type display and A-scan display in the instrument to measure the position, amplitude and length of the defect.

OmniPC-4.4R3 Software Description:

The software should have at least A, S, B, and C display functions, and have the function of positioning, addressing, and analyzing defects on the scanned image.

It can store and recall A, S, B, and C images, and can copy stored detection data to external storage space.

The software should have the Focus Rule function A, CG calibration function, and TCG (or DAC) calibration function.

The instrument should be capable of storing and resolving information about the relative position of each A-scan signal, such as the encoder position.

The off-line analysis software should be able to view the key parameters of the test.

8, the determination of the length of the defect:

If the maximum amplitude of the defect does not exceed 100% of the full screen and is greater than 20%, the maximum length of the A-scan echo amplitude reduced by 6 dB at different angles of the defect is found as the length of the defect. If the maximum amplitude of the defect is less than 20% higher than 10%, then the defect is found at different angles. The A-scan echo amplitude is reduced to 10% to measure the defect indication length by the 10% absolute sensitivity method.

If the maximum amplitude of the defect exceeds 100% of the full screen, the maximum length of the defect at which the A-scan echo amplitude is reduced to 50% of the full screen is found as the length of the defect.

Two defects adjacent in the length direction of the defect have a lengthwise spacing smaller than the smaller defect length and the distance between the two defects in the direction perpendicular to the length of the defect is less than 5 mm, and should be treated as a defect, and the sum of the two defect lengths is taken as Indicate the length (interval count). If the two defects are overlapped in the longitudinal direction projection, the distance between the left and right end points of the two defects projected in the longitudinal direction is taken as the indicated length.

9. Defect identification: marking the defect location of the inspected part;

According to the evaluation record, the measurement of the weld defect is carried out using a tape measure, and the surface of the product is marked with information including the length, depth and grade of the defect.

10. Judgment: The weld quality requirements of the tested parts meet the technical requirements of the customer.

Weld joints are not allowed to have defects such as cracks, unfused and incomplete penetration;

Defects with amplitudes below 10% are rated as Class I;

The quality classification of welded joints shall be determined according to the provisions of Table 2 below, such as in accordance with Class I standards:

11, the comparison results:

A total of 41 defects were found by phased array ultrasonic inspection, of which 15 were grade I and 26 were grade III.

15 Class I defects:

Five of them were sampled by ordinary ultrasound, three of which were Class I defects and two were not found. A defect was sampled by manual cutting.

26 Class III defects:

Sixteen were sampled by ordinary ultrasound, 11 of which were grade III and 5 were not found.

Eight were randomly selected by manual cut-off, and defects were found.

The phased array ultrasonic testing speed is faster than other detection methods, such as 18 m workpiece, phased array ultrasonic testing takes 30 minutes, and ordinary ultrasonic testing takes 90 minutes.

At the same time, it has been found that phased array ultrasonic testing is less affected by artificial factors, while ordinary ultrasonic testing and X-ray testing are greatly affected by the level of artificial defects.

Through the detection and verification comparison, not only the method of phased array ultrasonic detection is preliminarily grasped, but also the depth of the accuracy and the detection speed are relatively large compared with the traditional X-ray detection and ordinary ultrasonic detection. The advantage of the product should be said to be applied to the actual inspection, which will definitely improve the quality of the product.

Claims (6)

A phased array ultrasonic testing method for a welded joint of an aluminum alloy welded shell is characterized in that: a phased array probe is used perpendicular to the weld, and a straight line scan is performed along the straight pipe weld direction; the phased array probe conforms to JB/T In 11731, the phased array probe is composed of a plurality of wafers. The method of phased array ultrasonic testing for a welded joint of an aluminum alloy welded shell according to claim 1, characterized in that: two phased array probes are used for synchronous linear scanning, and two phased array probes are respectively arranged in straight tube welding. The same side of the seam, and on both sides of the straight pipe weld. The phased array ultrasonic testing method for a welded joint of an aluminum alloy welded shell according to claim 1 or 2, wherein when the welded joint is a longitudinal slit, the speed of the linear scanning is an axis of the aluminum alloy welded shell The direction is not more than 100mm/s. The phased array ultrasonic testing method for a welded joint of an aluminum alloy welded shell according to claim 1 or 2, wherein when the welded joint is a spiral welded joint, the speed of the linear scanning is along the axis of the spiral welded pipe 1 to 2 m/min. The phased array ultrasonic testing method for a weld of an aluminum alloy welded casing according to claim 1 or 2, wherein when the weld bead is a circumferential seam, the speed of the linear scanning is in the direction of the weld of the outer casing 1 ~2m/min. The method for phased array ultrasonic testing of a welded joint of an aluminum alloy welded shell according to claim 1 or 2, characterized in that: 10 ° C ~ 35 ° C water with pure, no bubbles and impurities is used as a phased array probe during scanning Coupling agent.