Dynamic sound velocity calibration and defect quantitative correction method for ultrasonic testing of steel structure weld

Abstract

The application discloses a steel structure weld ultrasonic detection method with dynamic sound velocity calibration and defect quantitative correction, and belongs to the technical field of steel structure weld detection. The steel structure weld ultrasonic detection method with dynamic sound velocity calibration and defect quantitative correction comprises identifying a workpiece self reference reflector, dynamic sound velocity calibration and dynamic DAC curve correction. The application fundamentally eliminates positioning system errors caused by material sound velocity differences through dynamic sound velocity calibration. The DAC reference is corrected based on the acoustic characteristics of the workpiece, which can more truly reflect the attenuation of ultrasonic waves in a specific workpiece, so that the defect quantitative result is closer to the actual situation, and the risk of misjudgment and missed judgment is reduced. The application converts the implicit correction depending on personnel experience into an explicit calibration process based on the geometric characteristics of the workpiece, so that the detection process is more standardized and objective, and the repeatability and comparability of detection results of different operators and at different times are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of steel structure weld inspection technology, specifically involving an ultrasonic inspection method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction. Background Technology

[0002] Steel structure engineering is a core structural form in modern architecture, bridges, energy facilities, and other fields, and its safety is of paramount importance. Welds, as the weakest link in a steel structure, directly determine the safety and durability of the overall structure due to their internal quality. Therefore, weld inspection is an indispensable part of engineering quality control.

[0003] Among numerous detection methods, A-mode ultrasonic testing technology has become the mainstream method for detecting internal weld defects (such as porosity, slag inclusions, lack of fusion, incomplete penetration, and cracks) due to its advantages such as large detection depth, accurate defect location, high sensitivity, and relatively low cost. The development of this technology has consistently focused on improving the reliability, accuracy, and standardization of detection. Its key technology lies in:

[0004] Defect location technology: Based on the propagation time (sound path) and probe parameters (K-value, leading edge), the spatial location of the defect is determined through geometric calculations. Its accuracy fundamentally depends on the accuracy of the sound wave propagation speed (sound velocity) within the material.

[0005] Defect quantification technology: The distance-amplitude curve (DAC curve) method is used to compare the echo height of the defect with the echo height of artificial regular reflectors at different depths to evaluate the equivalent size of the defect. The reliability of this technology depends on whether the DAC curve can truly reflect the attenuation law of ultrasonic waves in a specific workpiece material.

[0006] The continuous updates to industry standards (such as GB / T 11345 and NB / T 47013.3) aim to refine and unify operating procedures, but their technical foundation is still based on the two core points mentioned above.

[0007] In existing technologies, people typically follow the conventional manual ultrasonic testing methods specified in the latest national standard GB / T 11345-2023 and industry standard NB / T 47013.3-2023 to inspect the welds of steel structures. The detailed process is as follows:

[0008] Calibration preparation: All calibration work is carried out on standard test blocks (such as CSK-IA, CSK-IIIA). Before testing, the incident point, refraction angle (K value) and leading edge length of the probe must be measured on the standard test block and these parameters must be entered into the ultrasonic flaw detector.

[0009] Parameter presets and calibration:

[0010] Sound velocity preset: Set the material sound velocity in the instrument to a standard value (for example, for ordinary carbon steel, the transverse wave sound velocity is uniformly preset to 3230m / s), which is a fixed input value.

[0011] DAC curve plotting: On a standard test block, measure the echo amplitude of reference transverse holes at different depths (e.g., 10mm, 20mm, 30mm, etc.), and connect these points to form a standard distance-amplitude curve (DAC curve). Based on this, set the evaluation line, quantitative line, and rejection line.

[0012] Workpiece inspection: The calibrated instrument and probe are applied to the actual workpiece. During inspection, the probe moves on both sides of the weld, and the instrument screen displays an A-type waveform.

[0013] Defect assessment: When a defect echo is detected:

[0014] Positioning: The instrument automatically calculates and displays the depth and horizontal position of the defect based on the preset standard sound velocity and probe K value.

[0015] Quantitative analysis: The height of the defect echo is compared with the DAC curve plotted on a standard test block to determine its equivalent magnitude.

[0016] Although the latest standards have standardized the operating procedures and ensured the basic reliability of the tests, the technical solutions described above are based on the following idealized premises, which leads to inherent shortcomings that the standards themselves have not addressed:

[0017] 1. **Uniformly Assuming a Uniform Sound Velocity Leads to Positioning Errors:** Standard methods assume a uniform sound velocity of 3230 m / s for all steels. However, in actual engineering projects, steel's actual sound velocity varies significantly from the standard value due to differences in alloy composition, rolling processes, and heat treatment conditions (deviations can reach ±1% to 3% or higher). This results in unavoidable systematic errors in defect location, particularly in depth calculations. For thick workpieces or applications requiring precise positioning (such as defect rework), this error is unacceptable. Standards such as GB / T 11345-2023 acknowledge material differences but do not provide methods for calibrating the actual sound velocity of the workpiece on-site.

[0018] 2. Distortion of the DAC curve leads to inaccurate quantification: The standard DAC curve is derived from a standard test block, whose material, grain size, and surface condition cannot be exactly the same as the workpiece being inspected. Therefore, the attenuation law of ultrasonic waves in the actual workpiece differs from that in the standard test block. This results in a benchmark deviation in the quantitative assessment of defects based on the standard DAC curve, which may exaggerate small defects or underestimate large defects, affecting the accurate judgment of the hazard of defects.

[0019] 3. The correction of systematic errors relies on human experience and lacks objectivity: The systematic errors introduced by the material itself cannot be automatically eliminated within the framework of standard methods. Experienced testers may make subjective corrections through waveform characteristics, sound path perception, etc., but this lacks a unified standard, is not reproducible, and is difficult to quantify. For different operators, the consistency and reliability of test results are difficult to guarantee, making the test quality overly dependent on the "human" factor rather than the reliability of the "technology" itself. Summary of the Invention

[0020] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction.

[0021] The technical solution adopted to solve the above-mentioned technical problems is: an ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction, comprising the following steps:

[0022] S1. Identify the workpiece's own reference reflector;

[0023] S2. Dynamic sound velocity calibration: Measure and display the sound path Sm, calculate the actual sound path St, and back-calculate and input the actual sound velocity V of the workpiece.

[0024] S3, Dynamic DAC Curve Correction, generates a customized DAC curve using real sound speed and its own reflector;

[0025] S4. Perform standard scanning and evaluation based on actual parameters.

[0026] Furthermore, S2 includes steps S201, S202, and S203. In step S201, the plate thickness T is accurately measured. In step S202, two probes are placed at positions P1 and P2 respectively to find the root wave and record and display the sound path S1m and S2m. In step S203, the actual sound velocity Va is calculated using the sound path calculation formula and the sound velocity calculation formula.

[0027] Through the above technical solution, the staff can use the characteristics of the workpiece itself to back-calculate and establish the detection benchmark parameters specific to the workpiece, thereby obtaining data such as the actual sound velocity of the ultrasonic wave in the workpiece and the comprehensive attenuation coefficient under the detection conditions. The actual sound velocity is then input into the detection instrument to complete dynamic calibration. When the probe is at P1 and P2, the geometric path between its sound beam centerline and the root point R, i.e., its true sound path S1t and S2t, is unique and can be accurately calculated by the plate thickness T and the offset of the probe movement. By establishing the ratio between the true and displayed sound path and using the calculation formula, the unique actual sound velocity Va of the workpiece can be accurately back-calculated.

[0028] Furthermore, S3 includes steps S301 and S302. In step S301, the root reflection wave of the weld is used as the reference point for the maximum sound path. The height of the root echo is adjusted to a specified height and the point is recorded. In step S302, the instrument automatically generates a new DAC curve that conforms to the actual sound velocity and material attenuation characteristics of the current workpiece based on this reference point and in combination with the standard attenuation formula or another near-field reference point.

[0029] Through the above technical solution, the standard attenuation formula refers to the physical formula describing the attenuation law of ultrasonic wave amplitude with propagation distance in a material. In the field of ultrasonic testing, commonly used attenuation models include the exponential attenuation model A=A0×e^(-αS) or the logarithmic attenuation model. The attenuation amount (dB) is 20×log10(A0 / A)=k×S, where A is the echo amplitude, A0 is the initial amplitude or reference amplitude, S is the sound path, and α and k are attenuation coefficients related to the material. The instrument can calculate the approximate attenuation coefficient of the current workpiece based on the known S and A values ​​of the reference reflector reference point, combined with the above model, and then deduce the attenuation coefficient. The expected amplitude at other depths is obtained, and a DAC curve is generated. After the sound velocity calibration is completed, the instrument's depth measurement is accurate. Through the above operation of dynamic sound velocity calibration, the positioning system error caused by the difference in sound velocity of materials is fundamentally eliminated. The actual measurement shows that this method can reduce the positioning error by about 60%-80%, and the effect is more significant for deep defects in thick plates. Furthermore, since the DAC curve obtained by the above method is based on the acoustic characteristics of the workpiece itself, it can more realistically reflect the attenuation of ultrasonic waves in a specific workpiece, making the quantitative result of defects closer to the real situation and reducing the risk of misjudgment and omission.

[0030] Furthermore, the sound path calculation formula is S1t=2×√[T²+(offset 1)²] and S1t=2×√[T²+(offset 2)²], and the actual sound velocity calculation formula is Va=Vp×(S1t / S1m), where the offset is the horizontal distance from the probe incident point to the projection point of the reference reflector on the workpiece surface, and Vp is the preset sound velocity.

[0031] Furthermore, in step S1, the preferred reference reflector is the root corner of the weld.

[0032] With the above technical solution, the root of the weld is a feature of the workpiece being inspected. Ultrasonic waves will be reflected at its corners. After the instrument receives the reflected signal, a specific root reflection wave R can be formed on its screen. The inspection instrument can be a pulse reflection flaw detector.

[0033] Furthermore, in step S1, if the weld root cannot be used as a calibration reference body, then a reflector with clear geometric features, such as the inherent process hole, lock, and edge on the workpiece, is used as the calibration reference body. If the workpiece does not have the above structure or the above structure is not available, then a simple reflector of known size (such as a shallow flat-bottom hole) is artificially made in a non-critical area of ​​the workpiece being inspected.

[0034] The above technical solution ensures that weld inspection always has a reliable basis in the calibration process, avoiding the lack of calibration basis due to the inability to use the weld root. Prioritizing reflectors such as inherent process holes and interlocking seams on the workpiece allows for the use of their clear geometric features, reducing additional operations. These reflectors also closely match the actual structure of the workpiece, making the calibration data more consistent with the inspection scenario and reducing errors introduced by external reference bodies. If the inherent structure is unavailable, reflectors of known dimensions, such as shallow flat-bottomed holes, can be manually fabricated in non-critical areas to independently construct a standard reference, ensuring an uninterrupted calibration process. This approach avoids the risk of damage to critical areas and precisely controls calibration accuracy through known dimensions, ensuring the accuracy of subsequent defect detection and quantification. The overall solution balances practicality and rigor, establishing a stable calibration benchmark regardless of the initial conditions of the workpiece, providing crucial support for the reliability and consistency of inspection results, and preventing missed or incorrect judgments due to calibration issues. This flexible and standardized method of selecting calibration reference bodies can also adapt to weld inspection needs under different working conditions.

[0035] Furthermore, in steps S2 and S4, the inspection method for the weld strictly follows the scanning method specified in GB / T 11345-2023 or NB / T 47013.3-2023.

[0036] By employing the aforementioned technical solutions and strictly adhering to the scanning methods specified in GB / T 11345-2023 or NB / T 47013.3-2023, the quality and reliability of weld inspection can be significantly improved. Standardized line scanning, sector scanning, and hybrid scanning methods can accurately cover the weld bevel and heat-affected zone. Through fixed-angle or multi-angle beam combinations, key defects such as incomplete fusion and cracks can be effectively detected, reducing the risk of missed detections from single-angle scanning and ensuring consistency in the inspection process. Regardless of differences in personnel or equipment, reproducible results can be obtained through standardized calibration and scanning procedures, providing a unified basis for quality assessment. For critical scenarios such as pressure equipment, standard scanning methods combined with technologies such as full-focusing can achieve accurate defect location and quantification, with deviations controlled within stringent limits. This also meets industry defect acceptance threshold requirements, avoiding misjudgments. This not only ensures the safety of welded structures but also makes the inspection results authoritative and mutually recognized, supporting compliance audits and quality traceability.

[0037] Furthermore, in step S4, when a defect is detected, the instrument performs defect location calculations based on the actual sound velocity Va, and compares the echo amplitude of the defect with the corrected customized DAC curve for quantitative evaluation.

[0038] Through the above technical solution, since the instrument calculates the defect location based on the actual sound velocity of ultrasound within the workpiece under test, its positioning accuracy is significantly improved. Furthermore, since the instrument uses a corrected DAC curve for comparison, the quantitative results are more reliable. Through these steps, this method can perform dynamic sound velocity calibration and quantitative defect correction for each workpiece under test, effectively avoiding systematic errors caused by the difference between the preset sound velocity and the actual sound velocity. It also avoids the reference deviation caused by the difference between the attenuation law of ultrasound in the actual workpiece and the attenuation law of ultrasound in the standard test block, effectively improving detection accuracy. Moreover, it eliminates the need for testing personnel to correct the results based on experience and subjective feelings, reducing the dependence on the technical skills and experience of testing personnel.

[0039] Furthermore, in step S3, when calculating the speed of sound in step S2, an iterative method or a least squares method can also be used for fitting.

[0040] By using the above technical solution, the displayed sound path at multiple points on the reference body is measured and fitted with the actual geometric sound path to directly calculate the optimal actual sound speed value. This method has stronger anti-interference capabilities.

[0041] Furthermore, in step S3, the standard DAC curve may be subjected to an overall translation or slope correction of the path-amplitude relationship.

[0042] The above technical solution is a simplified but still effective method of correction.

[0043] The overall inventive concept of this invention lies in the creative construction of a dynamic calibration closed-loop system based on the geometric characteristics of the workpiece itself. The core technological contribution of this system is to innovate the traditional open-loop detection process that relies on standard test blocks and preset parameters into a closed-loop intelligent detection process that matches the acoustic characteristics of each individual workpiece in real time.

[0044] The various technical steps of this invention form a close synergistic relationship:

[0045] The step of identifying the workpiece's own reference reflector provides a reliable geometric benchmark for the entire calibration system;

[0046] The dynamic sound velocity calibration step calculates the actual sound velocity unique to the workpiece based on this geometric datum, thus solving the positioning system error.

[0047] The dynamic DAC curve correction step establishes a quantitative benchmark that conforms to the actual attenuation characteristics of the workpiece based on the accurate sound velocity and using the same reference reflector.

[0048] The standard scanning and evaluation steps utilize the aforementioned customized parameters for high-precision detection.

[0049] These four steps are interconnected and functionally coupled: the output of the previous step is the input prerequisite for the next step, and together they serve the unified purpose of achieving high-precision detection that matches the individual characteristics of the inspected workpiece. This synergistic relationship enables this method, as a whole technical solution, to produce significant technical effects that are superior to the simple superposition of the individual steps.

[0050] The beneficial effects of this invention are as follows:

[0051] 1. This invention fundamentally eliminates positioning system errors caused by material sound velocity differences through dynamic sound velocity calibration. By using a DAC reference corrected based on the acoustic characteristics of the workpiece itself, it can more realistically reflect the attenuation of ultrasonic waves in a specific workpiece, making the quantitative results of defects closer to the real situation and reducing the risk of misjudgment and omission.

[0052] 2. This invention transforms implicit corrections that rely on human experience into explicit calibration processes based on workpiece geometric features, making the inspection process more standardized and objective, and significantly improving the repeatability and comparability of inspection results from different operators and at different times.

[0053] To verify the technical effects of the present invention, the applicant conducted a systematic comparative experiment:

[0054] Experimental design: Five groups of steel plates of different materials (Q235, Q345, 16Mn, etc.) and different thicknesses (20mm, 40mm, 60mm) were selected, and weld test plates containing standard artificial defects (horizontal holes, flat bottom holes) were processed.

[0055] Experimental group setup:

[0056] Group A: Tested entirely according to the GB / T 11345-2023 standard method (preset sound velocity 3230m / s, standard test block DAC).

[0057] Group B: Only dynamic sound velocity calibration is performed, and quantification is carried out using standard DAC curves;

[0058] Group C: Uses a preset standard sound velocity, but uses the echo at the root of the workpiece to correct the amplitude of the DAC curve;

[0059] Group D: Adopting the complete solution of this invention (dynamic sound velocity calibration + dynamic DAC correction).

[0060] Experimental results:

[0061] Positioning accuracy: The average depth positioning error of Group D (the present invention) is only 18%-25% of that of Group A (the standard method), which is about 40% higher than that of Group B (sound velocity calibration only);

[0062] Quantitative accuracy: The defect equivalent assessment error in Group D was 65%-75% lower than that in Group A, and approximately 35% higher than that in Group C (DAC correction only);

[0063] Consistency of Results: When the test results were operated by three testers with different experience levels, the coefficient of variation (CV) of the test results in group D was only 30% of that in group A, which significantly improved the objectivity and repeatability of the test results.

[0064] The experimental data above show that there is a significant synergistic effect between the "dynamic sound velocity calibration" and "dynamic DAC correction" steps of the present invention. The overall accuracy improvement produced by the combination of the two is far greater than the effect of either step alone, which verifies the superiority of the overall technical solution of the present invention. Attached Figure Description

[0065] Figure 1 This is a flowchart illustrating an ultrasonic testing method for steel structure welds based on dynamic sound velocity calibration and quantitative defect correction according to an embodiment of the present invention.

[0066] Figure 2 yes Figure 1 A flowchart illustrating step S2;

[0067] Figure 3 yes Figure 1 A flowchart illustrating step S3. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0069] In this invention, unless otherwise stated, the following terms have the following meanings:

[0070] "Offset": refers to the horizontal distance from the incident point of the probe to the projection point of the reference reflector on the workpiece surface;

[0071] "Display sound path": refers to the ultrasonic propagation distance calculated and displayed by the ultrasonic flaw detector based on the preset sound velocity;

[0072] "True sound path": refers to the actual propagation path length of the ultrasonic wave calculated based on the workpiece geometry and probe position;

[0073] "Customized DAC curve": refers to a distance-amplitude evaluation benchmark curve specifically generated for a given workpiece based on its actual sound velocity and material attenuation characteristics.

[0074] like Figure 1 and Figure 2 As shown, an ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction includes the following steps:

[0075] S1: Identify the workpiece's own reference reflector;

[0076] S2: Dynamic sound velocity calibration, measuring and displaying the sound path Sm, calculating the true sound path St, and back-calculating and inputting the actual sound velocity V of the workpiece. S2 includes steps S201, S202, and S203. In step S201, the plate thickness T is accurately measured. In step S202, two probes are placed at positions P1 and P2 respectively to find the root wave, and the sound paths S1m and S2m are recorded and displayed. In step S203, the actual sound velocity Va is calculated using the sound path calculation formula and the sound velocity calculation formula. The operator can use the characteristics of the inspected workpiece itself to back-calculate the sound velocity. The detection reference parameters specific to the workpiece are calculated and established to obtain data such as the actual sound velocity of the ultrasonic wave in the workpiece under test and the comprehensive attenuation coefficient under the test conditions. The actual sound velocity is then input into the detection instrument to complete dynamic calibration. When the probe is at P1 and P2, the geometric path between its sound beam centerline and the root point R, i.e., its true sound path S1t and S2t, is unique and can be accurately calculated by the plate thickness T and the offset of the probe movement. By establishing the ratio between the true and displayed sound path and using the calculation formula, the unique actual sound velocity Va of the workpiece can be accurately calculated.

[0077] It should be noted that the calculation of the actual sound velocity in the above dynamic sound velocity calibration steps is not limited to a single proportional calculation method. As a better alternative, the displayed sound path of the reference reflector at multiple (three or more) different probe positions can be measured, and the corresponding true geometric sound path can be calculated for each. The optimal actual sound velocity value can then be obtained by fitting the results using an iterative method or the least squares method. For example, the equation system Smi = (Vp / Va) × Sti (where i = 1, 2, 3…) can be established, and Va can be solved using the least squares method. This method can effectively reduce the impact of single measurement errors and improve calibration accuracy and anti-interference capability.

[0078] like Figure 1 and Figure 3As shown, S3: Dynamic DAC curve correction. A customized DAC curve is generated using the actual sound velocity and its own reflector. S3 includes steps S301 and S302. In step S301, the root echo of the weld is used as the reference point for the maximum sound path. The root echo height is adjusted to a specified height and recorded. In step S302, the instrument automatically generates a new DAC curve that conforms to the actual sound velocity and material attenuation characteristics of the current workpiece, based on this reference point and combined with the standard attenuation formula or another near-field reference point. The standard attenuation formula is a physical formula describing the attenuation law of ultrasonic amplitude with propagation distance in a material. In the field of ultrasonic testing, commonly used attenuation models include the exponential attenuation model A=A0×e^(-αS) or the logarithmic attenuation model. Attenuation (dB) = 20×log10(A0 / A) = k×S, where A is the echo... Wave amplitude, A0 is the initial or reference amplitude, S is the sound path, and α and k are material-related attenuation coefficients. The instrument can calculate the approximate attenuation coefficient of the current workpiece based on the known S and A values ​​of the reference reflector reference point and the above model, and then deduce the expected wave amplitude at other depths to generate a DAC curve. After the sound velocity calibration is completed, the instrument's depth measurement is accurate. Through the above operation of dynamic sound velocity calibration, the positioning system error caused by the difference in sound velocity of materials is fundamentally eliminated. The actual measurement shows that this method can reduce the positioning error by about 60%-80%, especially for deep defects in thick plates. Moreover, since the DAC curve obtained by the above method is based on the acoustic characteristics of the workpiece itself, it can more realistically reflect the attenuation of ultrasonic waves in a specific workpiece, making the quantitative result of defects closer to the real situation and reducing the risk of misjudgment and omission.

[0079] Furthermore, a simplified implementation can be used to generate customized DAC curves in the dynamic DAC curve correction step. This involves shifting or correcting the slope of the original DAC curve drawn based on the standard test block after sound velocity calibration, ensuring that key points (such as the maximum path point) match the measured echo height of the reference reflector. While this simplified method is slightly less accurate than the complete generation method based on attenuation formulas, it is more convenient and suitable for applications requiring high efficiency.

[0080] like Figure 1 and Figure 2 As shown, S4: Standard scanning and evaluation are performed based on actual parameters. The sound path calculation formula is S1t=2×√[T²+(offset 1)²] and S1t=2×√[T²+(offset 2)²]. The actual sound velocity calculation formula is Va=Vp×(S1t / S1m), where the offset is the horizontal distance from the probe incident point to the projection point of the reference reflector on the workpiece surface, and Vp is the preset sound velocity.

[0081] like Figure 1As shown, in step S1, the preferred reference reflector is the corner of the weld root. The weld root is a feature of the workpiece being inspected. Ultrasonic waves will be reflected when passing through its corner. After the instrument receives the reflected signal, a specific root reflection wave R can be formed on its screen. The inspection instrument can be a pulse reflection flaw detector.

[0082] like Figure 1 As shown, in step S1, if the weld root cannot be used as a calibration reference body, then reflectors with clear geometric features, such as inherent process holes, interlocks, and edges on the workpiece, are used as calibration reference bodies. If the workpiece does not have the above structures or none of the above structures are usable, then a simple reflector of known size (such as a shallow flat-bottomed hole) is artificially made in a non-critical area of ​​the workpiece being inspected. This ensures that weld inspection always has a reliable basis in the calibration process, avoiding the lack of calibration basis due to the inability to use the weld root. Preferentially using reflectors such as inherent process holes and interlocks on the workpiece can rely on their clear geometric features, reduce additional operations, and at the same time fit the actual structure of the workpiece, making the calibration data more consistent with the inspection field. This approach reduces errors introduced by external reference bodies. If the inherent structure is unavailable, shallow flat-bottomed holes or other reflectors of known dimensions can be artificially fabricated in non-critical areas to autonomously construct a standard reference, ensuring uninterrupted calibration. This not only avoids the risk of damage to critical areas but also precisely controls calibration accuracy through known dimensions, ensuring the accuracy of subsequent defect detection and quantification. The overall solution balances practicality and rigor, establishing a stable calibration benchmark regardless of the initial conditions of the workpiece. This provides crucial support for the reliability and consistency of test results, avoiding missed or incorrect judgments due to calibration issues. This flexible and standardized method of selecting calibration reference bodies can also adapt to weld inspection needs under different working conditions.

[0083] like Figure 1 As shown, in steps S2 and S4, the inspection method for the weld strictly follows the scanning method specified in GB / T 11345-2023 or NB / T 47013.3-2023. The scanning methods specified in 47013.3-2023 can significantly improve the quality and reliability of weld inspection. The clearly defined line scanning, sector scanning, and hybrid scanning methods can accurately cover the weld bevel and heat-affected zone. By combining fixed-angle or multi-angle sound beams, key defects such as incomplete fusion and cracks can be effectively detected, reducing the risk of missed detection by single-angle scanning and ensuring the consistency of the inspection process. Regardless of differences in inspection personnel or equipment, reproducible results can be obtained through standardized calibration and scanning procedures, providing a unified basis for quality assessment. For critical scenarios such as pressure equipment, the standard scanning methods combined with technologies such as full focusing can achieve accurate defect location and quantification, with deviations controlled within a strict range. At the same time, it meets the industry's defect acceptance threshold requirements, avoiding misjudgments. This not only ensures the safety of welded structures but also makes the inspection results authoritative and mutually recognized, supporting compliance audits and quality traceability.

[0084] like Figure 1 As shown, in step S4, when a defect is detected, the instrument performs defect location calculation based on the actual sound velocity Va. The echo amplitude of the defect is compared with the corrected customized DAC curve for quantitative evaluation. Since the instrument performs defect location calculation based on the actual sound velocity of the ultrasonic wave within the workpiece under test, its location accuracy is significantly improved. Because the instrument uses the corrected DAC curve for comparison at this time, the quantitative result is also more reliable. Through the above steps, this method can perform dynamic sound velocity calibration and quantitative correction of defects for each workpiece under test, thereby effectively avoiding the systematic error caused by the difference between the preset sound velocity and the actual sound velocity, and avoiding the reference deviation caused by the difference between the attenuation law of ultrasonic waves in the actual workpiece and the attenuation law of ultrasonic waves in the standard test block. This effectively improves the detection accuracy and eliminates the need for inspectors to correct the results based on experience and subjective feelings, reducing the dependence on the inspectors' skills and experience during the inspection.

[0085] like Figure 1 and Figure 3 As shown, in step S3, when calculating the sound speed in step S2, an iterative method or least squares method can also be used for fitting. By measuring the displayed sound path at multiple points on the reference body and fitting it with the actual geometric sound path, the optimal actual sound speed value can be directly calculated. This method has stronger anti-interference ability.

[0086] like Figure 1 and Figure 3 As shown, in step S3, the standard DAC curve can also be shifted as a whole or its slope corrected by adjusting the path-amplitude relationship. This is a simplified but still effective correction method.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. An ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction, characterized in that: Includes the following steps: S1. Identify the workpiece's own reference reflector; S2. Dynamic sound velocity calibration: Measure and display the sound path Sm, calculate the actual sound path St, and back-calculate and input the actual sound velocity V of the workpiece. S3, Dynamic DAC Curve Correction, generates a customized DAC curve using real sound speed and its own reflector; S4. Perform standard scanning and evaluation based on actual parameters.

2. The ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction according to claim 1, characterized in that, The S2 includes steps S201, S202, and S203. In step S201, the plate thickness T is accurately measured. In step S202, two probes are placed at positions P1 and P2 respectively to find the root wave and record and display the sound path S1m and S2m. In step S203, the actual sound velocity Va is calculated using the sound path calculation formula and the sound velocity calculation formula.

3. The ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction according to claim 1, characterized in that, S3 includes steps S301 and S302. In step S301, the root reflection wave of the weld is used as the reference point for the maximum sound path. The height of the root echo is adjusted to a specified height and the point is recorded. In step S302, the instrument automatically generates a new DAC curve that conforms to the actual sound velocity and material attenuation characteristics of the current workpiece based on this reference point and in combination with the standard attenuation formula or another near-field reference point.

4. The ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction according to claim 2, characterized in that, The sound path calculation formula is S1t=2×√[T²+(offset 1)²] and S1t=2×√[T²+(offset 2)²], and the actual sound velocity calculation formula is Va=Vp×(S1t / S1m), where the offset is the horizontal distance from the incident point of the probe to the projection point of the reference reflector on the workpiece surface, and Vp is the preset sound velocity.

5. The ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction according to claim 1, characterized in that, In step S1, the preferred reference reflector is the root corner of the weld.

6. The ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction according to claim 4, characterized in that, In step S1, if the weld root cannot be used as a calibration reference body, then reflectors with clear geometric features, such as process holes, locks, and edges inherent on the workpiece, are used as calibration reference bodies. If the workpiece does not have the above structure or the above structure is not available, then a simple reflector of known size (such as a shallow flat-bottomed hole) is artificially made in a non-critical area of ​​the workpiece being inspected.

7. The ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction according to claim 1, characterized in that, In steps S2 and S4, the inspection method for the weld strictly follows the scanning method specified in GB / T 11345-2023 or NB / T 47013.3-2023.

8. The ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction according to claim 1, characterized in that, In step S4, when a defect is detected, the instrument performs defect location calculations based on the actual sound velocity Va, and compares the echo amplitude of the defect with the corrected customized DAC curve for quantitative evaluation.

9. The ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction according to claim 1, characterized in that, When calculating the speed of sound in step S2, an iterative method or a least squares method can also be used for fitting.

10. The ultrasonic testing method for steel structure welds with dynamic sound velocity calibration and quantitative defect correction according to claim 1, characterized in that, In step S3, the standard DAC curve may also be subjected to an overall translation or slope correction of the path-amplitude relationship.

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