A method for ultrasonic nondestructive testing of residual stress in titanium alloy tubes

Abstract

The present invention discloses a residual stress ultrasonic nondestructive testing method for titanium alloy tubes, which relates to the field of metal detection technology and includes the following steps: performing surface residual stress benchmark measurement, selecting ultrasonic emission frequency, pre-processing the surface of titanium alloy tubes, multi-mode ultrasonic beam focusing scanning, establishing an ultrasonic velocity and stress correlation model, acoustic anomaly identification of asymmetric stress areas, three-dimensional imaging of residual stress, and stress distribution correction. The residual stress ultrasonic nondestructive testing method for titanium alloy tubes overcomes the shortcomings of traditional detection methods in terms of accuracy, adaptability, and non-destructiveness by combining ultrasonic signal processing, complex stress correlation modeling, and acoustic anomaly identification technology. The distribution and concentration of residual stress in titanium alloy tubes can be evaluated efficiently and accurately, effectively improving the reliability and environmental adaptability of the detection results.

Description

Technical Field

[0001] The invention relates to the technical field of metal detection, in particular to a residual stress ultrasonic nondestructive detection method for a titanium alloy tube. Background Art

[0002] Titanium alloy tubes are widely used in aerospace, chemical and medical fields due to their excellent strength-to-weight ratio, corrosion resistance and high temperature performance. However, during the manufacturing, processing and service process, titanium alloy tubes will inevitably produce residual stress, which will affect their mechanical properties, fatigue resistance and service life. Therefore, accurate detection of residual stress in titanium alloy tubes is particularly important. Traditional residual stress detection methods mainly include destructive methods (such as blind hole method) and semi-destructive methods (such as X-ray diffraction method). Although these methods have certain accuracy under specific conditions, they are usually subject to the following limitations:

[0003] Poor adaptability to complex conditions: In the presence of asymmetric stress, existing technologies are difficult to fully reflect the true stress state of the material.

[0004] High sensitivity to environmental interference: Many detection methods are highly sensitive to temperature, changes in material microstructure (such as grain orientation) and acoustic wave coupling conditions, and the stability of detection results is poor.

[0005] Insufficient non-destructiveness: Some detection methods require drilling or abrasion on the material surface, which affects the integrity of the material and cannot meet the needs of certain high-precision application scenarios.

[0006] Ultrasonic nondestructive testing has gradually become the mainstream direction of residual stress detection due to its strong penetration, non-destructiveness and high detection efficiency. However, existing ultrasonic testing technology usually relies on a single acoustic property (such as sound velocity or reflection amplitude), which is still insufficient when dealing with asymmetric areas. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a method for ultrasonic nondestructive testing of residual stress of a titanium alloy tube to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] In a first aspect, an embodiment of the present invention provides a method for ultrasonic nondestructive testing of residual stress of a titanium alloy tube, comprising the following steps:

[0010] S1. Conducting surface residual stress benchmark measurement;

[0011] S2, select the ultrasonic emission frequency;

[0012] S3, pre-treating the surface of the titanium alloy tube;

[0013] S4, performing multi-mode ultrasonic beam focusing scanning to obtain scanned ultrasonic signal data;

[0014] S5, establishing a sound velocity stress correlation model for correlation between ultrasonic velocity and stress in ultrasonic signals;

[0015] S6. Identify acoustic anomalies in the asymmetric stress region, and compare and analyze with the acoustic velocity stress correlation model to identify acoustic anomalies in the asymmetric stress region of the titanium alloy tube;

[0016] S7. Based on the identified acoustic anomalies, three-dimensional imaging of residual stress is performed to restore the stress distribution state;

[0017] S8. Perform stress distribution correction based on residual stress three-dimensional imaging.

[0018] To further optimize the technical solution, in step S1, the benchmark measurement includes the following process:

[0019] Select the measurement point;

[0020] Laser scattering detects initial stress;

[0021] Point ultrasonic measurement assisted verification;

[0022] Correction for temperature effects;

[0023] Data comparison and verification;

[0024] Initial stress distribution diagram drawing;

[0025] Benchmark data storage and annotation;

[0026] Stress deviation range is determined.

[0027] To further optimize the technical solution, in step S2, an ultrasonic emission frequency for residual stress detection is selected based on the density and elastic modulus of the titanium alloy;

[0028] Computational and simulation methods are used to analyze the absorption, scattering and attenuation characteristics of titanium alloy tubes to ultrasonic waves of different frequencies, and the optimal frequency range that can penetrate deep into the material and is not easily affected by surface roughness is selected.

[0029] To further optimize the technical solution, in step S3, the preprocessing includes:

[0030] Treat the surface of the titanium alloy tube inspection area, clean the surface with fine sandpaper or micro-sandblasting technology to remove the oxide layer, stains and tiny protrusions;

[0031] At the same time, in view of the reflection attenuation phenomenon on the surface of titanium alloy, a layer of high-impedance ultrasonic coupling agent or thin film coating is applied to improve the signal coupling effect.

[0032] To further optimize the technical solution, in step S5, the relationship between the ultrasonic sound velocity and the internal stress of the material is utilized, and through the experimental calibration method, the change law of the sound velocity of the titanium alloy under different stress states is curve-fitted to establish a sound velocity-stress correlation model specifically for the titanium alloy tube.

[0033] To further optimize the technical solution, the acoustic velocity stress correlation model includes:

[0034] Assume that the ultrasonic speed in the material is , the stress state is , the temperature is , the grain orientation factor is , the model is as follows:

[0035] ;

[0036] in,

[0037] : No stress, standard temperature Initial sound velocity under

[0038] : current stress value;

[0039] : Yield strength of the material, used to normalize stress effects;

[0040] : correspond to the current temperature and reference temperature respectively;

[0041] : Grain orientation factor, which describes the effect of material microstructure on ultrasonic propagation;

[0042] : The angle between the direction of sound wave propagation and the main orientation of the grain;

[0043] : stress influence coefficients, controlling linear and quadratic stress effects respectively;

[0044] : Temperature effect coefficient, used to correct the deviation of sound velocity with temperature change;

[0045] : Grain orientation influence coefficient, reflecting the modulation of the sound velocity by the internal anisotropy of the material.

[0046] To further optimize the technical solution, in step S6, an identification model is used to identify acoustic anomalies caused by asymmetric stress areas;

[0047] Through time domain and frequency domain analysis, the characteristic values ​​of amplitude change, phase delay and harmonic distortion in the ultrasonic signal are extracted and compared with the sound velocity stress correlation model.

[0048] To further optimize the technical solution, the recognition model includes:

[0049] Assume that the amplitude of the ultrasonic signal at a certain point is , the phase is , the frequency is , the current stress state is , the comprehensive characteristic function of acoustic anomaly caused by asymmetric stress is , the model is as follows:

[0050] ;

[0051] in,

[0052] : Weight coefficient, used to balance the contribution of different features to anomaly recognition;

[0053] : The acceleration of the signal amplitude reflects the dramatic change of sound wave reflection in the asymmetric area;

[0054] : The acceleration of the signal phase, describing the nonlinear change of the acoustic wave phase delay;

[0055] : Normalization of frequency offset reveals the modulation effect of asymmetric regions on the frequency of sound waves;

[0056] : Harmonic energy ratio offset, reflecting the high-order harmonic distortion caused by nonlinear effects;

[0057] : Signal acquisition time range.

[0058] Further optimize this technical solution, in the recognition model, when Exceeding the preset threshold , the current area is judged to be an asymmetric stress anomaly area.

[0059] To further optimize the technical solution, in step S8, based on the three-dimensional imaging of residual stress, the distribution of residual stress is accurately corrected, and the detection accuracy is automatically optimized by continuously adjusting the parameters of the acoustic velocity stress correlation model, and the interference of detection environment factors is eliminated;

[0060] The final correction result will provide a high-precision quantitative characterization of the residual stress, providing a reliable basis for material performance evaluation and defect prediction.

[0061] In a second aspect, an embodiment of the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program instructions are executed by the processor, the steps of a method for ultrasonic nondestructive testing of residual stress of a titanium alloy tube as described in the first aspect of the present invention are implemented.

[0062] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, the steps of a method for ultrasonic nondestructive testing of residual stress of a titanium alloy tube as described in the first aspect of the present invention are implemented.

[0063] Compared with the prior art, the present invention provides a method for ultrasonic nondestructive testing of residual stress of titanium alloy tubes, which has the following beneficial effects:

[0064] The ultrasonic nondestructive testing method for residual stress of titanium alloy tubes overcomes the shortcomings of traditional testing methods in terms of accuracy, adaptability and non-destructiveness by combining ultrasonic signal processing, stress correlation modeling and acoustic anomaly recognition technology. It can efficiently and accurately evaluate the distribution and concentration of residual stress in titanium alloy tubes, effectively improve the reliability and environmental adaptability of the test results, and is suitable for nondestructive testing of residual stress under complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0066] Figure 1 A schematic diagram of the process of ultrasonic nondestructive testing of residual stress of a titanium alloy tube proposed by the present invention;

[0067] Figure 2 A schematic diagram of a flow chart of residual stress reference measurement in a residual stress ultrasonic nondestructive testing method for a titanium alloy tube proposed by the present invention;

[0068] Figure 3 A schematic flow chart of a sonic velocity-stress correlation model in a residual stress ultrasonic nondestructive testing method for a titanium alloy tube proposed by the present invention;

[0069] Figure 4 The present invention provides a schematic flow chart of an identification model in a residual stress ultrasonic nondestructive testing method for a titanium alloy tube. DETAILED DESCRIPTION

[0070] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0071] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0072] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0073] Embodiment 1:

[0074] Reference Figure 1 to Figure 4 , which is the first embodiment of the present invention, provides a method for ultrasonic nondestructive testing of residual stress of a titanium alloy tube, comprising the following steps:

[0075] S1. Conducting surface residual stress benchmark measurement

[0076] This benchmark measurement is used to confirm the uniformity and original stress level during the titanium alloy tube manufacturing process and provide a comparative basis for subsequent residual stress detection. The stability of the surface coupling condition is further verified by comparing the difference in sound velocity changes with the stress-free area.

[0077] In this embodiment, the benchmark measurement includes the following process:

[0078] Select measurement points: According to the geometry and process characteristics of the titanium alloy tube, select multiple measurement points evenly, and select the annular and axial distribution points along the outer surface of the tube wall as reference points. Priority should be given to areas where stress concentration or material property changes may occur (such as welding points or hot processing areas). The distribution of these points must ensure coverage and representativeness in order to form an accurate initial stress distribution map.

[0079] Laser scattering to detect initial stress: Use low-stress laser scattering method to measure stress at selected measurement points. Aim the laser emitting device at the detection point and control the laser incident angle (generally 45 degrees); stimulate tiny elastic deformation on the surface of the material and collect scattered light signals; analyze the frequency shift and scattering pattern changes of the light signal, and deduce the magnitude of the surface stress based on the photoelastic effect.

[0080] Point ultrasonic measurement assisted verification: Use point ultrasonic method to perform auxiliary measurement on the same inspection point.

[0081] Temperature effect correction: During the measurement process, the ambient temperature of the measuring point is monitored in real time to compensate for the measurement deviation caused by thermal expansion or thermal strain. Through accurate temperature compensation, the test results are corrected to the stress value at the standard temperature (such as 25°C) to ensure the comparability of the results.

[0082] Data comparison and verification: Compare and analyze the stress results of each measurement point. If there are abnormal deviations in the measurement results of multiple points in the same area, it is necessary to re-measure or check whether the surface treatment and coupling state are consistent. By comparing the sound velocity and stress of stress-free areas (such as initial reference points or areas with clear design characteristics), the stability and accuracy of the measurement system can be further verified.

[0083] Initial stress distribution diagram drawing: The data of each measurement point is interpolated to generate the initial stress distribution diagram of the titanium alloy tube surface. It intuitively shows the stress difference formed during the manufacturing process and can be used as a calibration reference and comparison basis for subsequent residual stress detection.

[0084] Benchmark data storage and annotation: The measurement data and distribution diagrams are stored in the detection system and clearly annotated with the measurement conditions (temperature, coupling mode, etc.) and equipment parameters for quick recall and comparison in subsequent detection processes.

[0085] Determination of stress deviation range: Based on the measured data, determine the stress deviation range that may be formed during the manufacturing process, and use this range as a reference value for residual stress detection (such as the allowable stress variation range). This value will guide the identification and location of abnormal stress in subsequent detection.

[0086] S2. Select the ultrasonic emission frequency

[0087] In this embodiment, the ultrasonic emission frequency for residual stress detection is selected based on the density and elastic modulus of the titanium alloy;

[0088] Computational and simulation methods are used to analyze the absorption, scattering and attenuation characteristics of titanium alloy tubes to ultrasonic waves of different frequencies, and the optimal frequency range that can penetrate deep into the material and is not easily affected by surface roughness is selected.

[0089] For example, for thicker titanium alloy tubes, low-frequency ultrasound can be selected to achieve deeper penetration, while for thin-walled tubes, high-frequency ultrasound can be selected to improve detection resolution. By dynamically adjusting the ultrasonic frequency to match the material properties, it is ensured that the changing characteristics of residual stress can be effectively captured.

[0090] S3. Pre-treat the surface of the titanium alloy tube

[0091] In this embodiment, the preprocessing includes:

[0092] In order to ensure the stability and accuracy of ultrasonic wave propagation on the surface of titanium alloy tube, the surface of the detection area of ​​titanium alloy tube is treated, and the surface is cleaned by fine sandpaper or micro sandblasting technology to remove the oxide layer, stains and tiny protrusions to ensure that the surface finish meets the requirements of sound wave propagation;

[0093] At the same time, in view of the reflection attenuation phenomenon on the surface of titanium alloy, a layer of high-impedance ultrasonic coupling agent or thin film coating is applied to improve the signal coupling effect, which can effectively reduce the scattering and attenuation of sound waves and improve the reliability and sensitivity of subsequent detection.

[0094] S4, multi-mode ultrasonic beam focusing scanning

[0095] In this embodiment, multi-mode ultrasonic beam technology, including longitudinal waves, shear waves and surface waves, is used to perform all-round scanning of the titanium alloy tube through an array transducer. The focus of the ultrasonic beam is to form a high-energy-density sound field in the detection target area to improve the detection sensitivity of stress distribution. During the scanning process, the excitation angle of the transducer and the delay of the array channel are dynamically controlled to ensure that the sound waves can penetrate into the microstructure areas of different depths and angles.

[0096] This multi-mode scanning method can effectively overcome the limitations of single-mode detection and capture more comprehensive stress information.

[0097] S5. Establishment of ultrasonic velocity and stress correlation model

[0098] In this embodiment, the relationship between ultrasonic sound velocity and internal stress of the material is used, and the change law of sound velocity of titanium alloy under different stress states is curve fitted by experimental calibration method to establish a sound velocity stress correlation model specifically for titanium alloy tubes;

[0099] The acoustic velocity stress correlation model includes:

[0100] Assume that the ultrasonic speed in the material is , the stress state is , the temperature is , the grain orientation factor is , the model is as follows:

[0101] ;

[0102] in,

[0103] : No stress, standard temperature Initial sound velocity under

[0104] : current stress value;

[0105] : Yield strength of the material, used to normalize stress effects;

[0106] : Current temperature and reference temperature;

[0107] : Grain orientation factor, which describes the effect of material microstructure on ultrasonic propagation;

[0108] : The angle between the direction of sound wave propagation and the main orientation of the grain;

[0109] : stress influence coefficients, controlling linear and quadratic stress effects respectively;

[0110] : Temperature effect coefficient, used to correct the deviation of sound velocity with temperature change;

[0111] : Grain orientation influence coefficient, reflecting the modulation of the sound velocity by the internal anisotropy of the material.

[0112] When used, the model includes:

[0113] Step 1: Initial stress-free sound velocity Determination of

[0114] Under laboratory conditions, ultrasonic propagation experiments were carried out on stress-free titanium alloy tubes at standard temperature. Measure the speed of sound , providing initial values ​​for the model's benchmark.

[0115] Step 2: Calibration of stress influencing parameters

[0116] Obtain the sound velocity change data of titanium alloy materials by applying known stress (for example, using a tensile test or a static loading test). Fit the experimental data to determine the stress influence coefficient and .

[0117] : Characterizes the linear effect of stress on the speed of sound and is sensitive to small stress ranges.

[0118] : Characterizes the nonlinear effect of stress on the speed of sound and can capture the significant features of the change in speed of sound under large stress.

[0119] Step 3: Determination of temperature correction factor

[0120] Repeat the stress-free sound velocity measurement at different temperatures to analyze the linear effect of temperature on the sound velocity and determine Through experiments, it was found that the change of sound velocity of titanium alloy materials may be proportional to the temperature sensitivity.

[0121] Step 4: Calculation of grain orientation factor

[0122] The electron backscatter diffraction (EBSD) technique was used to determine the main orientation of the titanium alloy tube grains and calculate By introducing the angle , combined with the cosine modulation of the grains on the speed of sound in the model, can effectively reflect the anisotropic propagation characteristics inside the material.

[0123] Step 5: Real-time stress measurement

[0124] During the test, by measuring the current sound speed and temperature , the residual stress can be deduced :

[0125]

[0126] This formula decomposes the change in sound speed into the combined effects of stress, temperature and grain size through reverse calculation, thereby obtaining the current stress value.

[0127] Step 6: Global stress distribution analysis

[0128] Combined with the model, the stress value of each point is calculated and analyzed.

[0129] Traditional models usually assume that the effect of stress on sound velocity is a linear relationship. However, this model can more accurately describe the change law of sound velocity under larger residual stress by introducing quadratic nonlinear effects.

[0130] The model incorporates the grain orientation factor , combined with the propagation direction angle , which can capture the modulation effect of the inhomogeneity of the microstructure inside the titanium alloy on the sound velocity. At the same time, it improves the applicability of the detection in the actual environment and avoids the measurement error caused by the ambient temperature fluctuation.

[0131] S6. Acoustic anomaly identification in asymmetric stress regions

[0132] In this embodiment, an identification model is used to identify acoustic anomalies caused by asymmetric stress areas;

[0133] Through time domain and frequency domain analysis, the characteristic values ​​of amplitude change, phase delay and harmonic distortion in the ultrasonic signal are extracted and compared with the sound velocity stress correlation model. Asymmetric areas often show obvious acoustic anomaly characteristics, which can be used as an important indicator of potential stress concentration points and further verify the non-uniformity of residual stress distribution.

[0134] Furthermore, the recognition model includes:

[0135] Assume that the amplitude of the ultrasonic signal at a certain point is , the phase is , the frequency is , the current stress state is , the comprehensive characteristic function of acoustic anomaly caused by asymmetric stress is , the model is as follows:

[0136] ;

[0137] in,

[0138] : Weight coefficient, used to balance the contribution of different features to anomaly recognition;

[0139] : The acceleration of the signal amplitude reflects the dramatic change of sound wave reflection in the asymmetric area;

[0140] : The acceleration of the signal phase, describing the nonlinear change of the acoustic wave phase delay;

[0141] : Normalization of frequency offset reveals the modulation effect of asymmetric regions on the frequency of sound waves;

[0142] : Harmonic energy ratio offset, reflecting the high-order harmonic distortion caused by nonlinear effects;

[0143] : Signal acquisition time range;

[0144] when Exceeding the preset threshold , the current area is judged to be an asymmetric stress anomaly area.

[0145] When used, the model includes:

[0146] Step 1: Signal acquisition and preprocessing

[0147] The ultrasonic transducer is used to collect the acoustic wave signals at each measuring point of the titanium alloy tube to obtain the amplitude , Phase ,frequency Harmonic Energy . Background noise is removed by filtering, and the signal is normalized to unify the feature dimension.

[0148] Step 2: Amplitude and phase feature extraction

[0149] By calculation and , analyze the drastic changes of the signal.

[0150] Step 3: Frequency offset detection

[0151] Calculate the actual signal frequency With reference frequency The Difference :

[0152]

[0153] Step 4: Harmonic Distortion Analysis

[0154] Calculate the offset of the high-order harmonic energy ratio:

[0155]

[0156] Step 5: Calculate the comprehensive abnormal characteristics

[0157] The absolute values ​​of all features are weighted integral to obtain the comprehensive abnormal features By adjusting the weights , the best feature combination is determined experimentally to maximize recognition accuracy.

[0158] Step 6: Identify and mark abnormal areas

[0159] For each measuring point Values ​​and Thresholds For comparison, if , then mark the point as an asymmetric stress anomaly area. Threshold It can be determined based on statistical analysis of the experimental data distribution.

[0160] Traditional methods may rely on a single feature (such as amplitude change or frequency drift). This model significantly improves the sensitivity and accuracy of anomaly identification through multi-dimensional analysis of amplitude, phase, frequency and harmonics.

[0161] By calculating high-order derivatives and harmonic energy, subtle changes that cannot be revealed by traditional linear models can be captured.

[0162] This allows the acoustic anomalies in the asymmetric stress area of ​​the titanium alloy tube to be identified efficiently and accurately, providing a solid foundation for subsequent residual stress distribution analysis and tube quality assessment.

[0163] S7. Perform three-dimensional imaging of residual stress

[0164] In this embodiment, based on the acoustic anomaly of the asymmetric stress region of the titanium alloy tube, a three-dimensional reconstruction algorithm is used to generate a three-dimensional image of the residual stress in the titanium alloy tube, and the image is compared with the initial stress distribution map to restore the stress distribution state.

[0165] S8. Stress distribution correction

[0166] In this embodiment, based on the three-dimensional imaging of residual stress, the distribution of residual stress is accurately corrected, and the detection accuracy is automatically optimized by continuously adjusting the parameters of the acoustic velocity stress correlation model, and the interference of detection environment factors is eliminated;

[0167] The final correction result will provide a high-precision quantitative characterization of the residual stress, providing a reliable basis for material performance evaluation and defect prediction.

[0168] Embodiment 2:

[0169] This embodiment also provides a computer device, which is suitable for a residual stress ultrasonic nondestructive testing method for a titanium alloy tube, and includes a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the residual stress ultrasonic nondestructive testing method proposed in the above embodiment.

[0170] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the residual stress ultrasonic nondestructive testing method proposed in the above embodiment is implemented.

[0171] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covered on the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0172] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0173] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0174] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk case (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0175] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit with a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit with a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0176] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for ultrasonic nondestructive testing of residual stress of titanium alloy tubes, characterized in that: The following steps are involved: S1. Conducting surface residual stress benchmark measurement; S2, select the ultrasonic emission frequency; S3, pre-treating the surface of the titanium alloy tube; S4, performing multi-mode ultrasonic beam focusing scanning to obtain scanned ultrasonic signal data; S5, establishing a sound velocity stress correlation model for correlation between ultrasonic velocity and stress in ultrasonic signals; By using the relationship between ultrasonic sound velocity and internal stress of materials and experimental calibration method, the change law of sound velocity of titanium alloy under different stress states is fitted by curve fitting, and a sound velocity stress correlation model specifically for titanium alloy tubes is established; The acoustic velocity stress correlation model includes: Assume that the ultrasonic speed in the material is , the model is as follows: ； in, : Reference temperature Initial sound velocity under : stress state; : Yield strength of the material, used to normalize stress effects; : Current temperature; : reference temperature; : Grain orientation factor, which describes the effect of material microstructure on ultrasonic propagation; : The angle between the direction of sound wave propagation and the main orientation of the grain; : Control linear stress influence coefficient; : stress influence coefficient controlling the secondary stress effect; : Temperature effect coefficient, used to correct the deviation of sound velocity with temperature change; : Grain orientation influence coefficient, reflecting the modulation of the internal anisotropy of the material on the sound velocity; S6. Identify acoustic anomalies in the asymmetric stress region, and compare and analyze with the acoustic velocity stress correlation model to identify acoustic anomalies in the asymmetric stress region of the titanium alloy tube; Using identification models to identify acoustic anomalies caused by asymmetric stress areas; Through time domain and frequency domain analysis, the characteristic values ​​of amplitude change, phase delay and harmonic distortion in the ultrasonic signal are extracted and compared with the sound velocity stress correlation model; The recognition model includes: Assume that the amplitude of the ultrasonic signal at a certain point is , the phase is , the frequency is , the comprehensive characteristic function of acoustic anomaly caused by asymmetric stress is , the model is as follows: ； in, : Weight coefficient, used to balance the contribution of different features to anomaly recognition; : The acceleration of the signal amplitude reflects the dramatic change of sound wave reflection in the asymmetric area; : The acceleration of the signal phase, describing the nonlinear change of the acoustic wave phase delay; : Normalization of frequency offset reveals the modulation effect of asymmetric regions on the frequency of sound waves; : Harmonic energy ratio offset, reflecting the high-order harmonic distortion caused by nonlinear effects; : Signal acquisition time range; S7. Based on the identified acoustic anomalies, three-dimensional imaging of residual stress is performed, and compared with the surface residual stress benchmark to restore the stress distribution state; S8. Perform stress distribution correction based on residual stress three-dimensional imaging.

2. The method for ultrasonic nondestructive testing of residual stress of a titanium alloy tube according to claim 1, characterized in that: In step S1, the benchmark measurement includes the following process: Select the measurement point; Laser scattering detects initial stress; Point ultrasonic measurement to assist verification; Correction for temperature effects; Data comparison and verification; Initial stress distribution diagram drawing; Benchmark data storage and annotation; Stress deviation range is determined.

3. The method for ultrasonic nondestructive testing of residual stress of a titanium alloy tube according to claim 1, characterized in that: In the step S2, based on the density and elastic modulus of the titanium alloy, an ultrasonic emission frequency for residual stress detection is selected; Computational and simulation methods are used to analyze the absorption, scattering and attenuation characteristics of titanium alloy tubes to ultrasonic waves of different frequencies, and the optimal frequency range that can penetrate deep into the material and is not easily affected by surface roughness is selected.

4. The method for ultrasonic nondestructive testing of residual stress of a titanium alloy tube according to claim 1, characterized in that: In step S3, the preprocessing includes: Treat the surface of the titanium alloy tube inspection area, clean the surface with fine sandpaper or micro-sandblasting technology to remove the oxide layer, stains and tiny protrusions; At the same time, in view of the reflection attenuation phenomenon on the surface of titanium alloy, a layer of high-impedance ultrasonic coupling agent or thin film coating is applied to improve the signal coupling effect.

5. The method for ultrasonic nondestructive testing of residual stress of a titanium alloy tube according to claim 1, characterized in that: In the identification model, when Exceeding the preset threshold , the current area is judged to be an asymmetric stress anomaly area.

6. The method for ultrasonic nondestructive testing of residual stress of a titanium alloy tube according to claim 1, characterized in that: In the step S8, based on the three-dimensional imaging of residual stress, the distribution of residual stress is accurately corrected, and the detection accuracy is automatically optimized by continuously adjusting the parameters of the acoustic velocity stress correlation model, and the interference of detection environment factors is eliminated; The final correction result will provide a high-precision quantitative characterization of the residual stress, providing a reliable basis for material performance evaluation and defect prediction.

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