A method and system for ultrasonic flaw detection of titanium alloy bars

Abstract

The present application relates to the technical field of ultrasonic flaw detection of titanium alloy bars, and specifically to a method and system for ultrasonic flaw detection of titanium alloy bars, the method comprising: obtaining ultrasonic signals at each position; obtaining a reception time sequence at each position; obtaining the true defectivity at each position based on the difference between adjacent peaks in the ultrasonic signal at each position, the degree of dispersion of all peaks, the average level of the reception time sequence, and the difference between the reception time sequences at each position and those at adjacent positions; obtaining a signal anomaly factor at each position based on the degree of dispersion of the amplitude average level of all modal components at each position, the total number of modal components, and the energy concentration and bandwidth of the ultrasonic signal at each position in the frequency domain; obtaining a defect factor at each position, and then determining whether a defect exists at each position. The present application improves the accuracy of ultrasonic flaw detection of titanium alloy bars by analyzing the signal characteristics of true defects within the titanium alloy bars.

Description

Technical Field

[0001] The present application relates to the technical field of ultrasonic flaw detection of titanium alloy bars, and in particular to a method and system for ultrasonic flaw detection of titanium alloy bars. Background Art

[0002] Titanium alloy bars are widely used in aerospace, marine engineering, and petrochemical industries due to their low density, high specific strength, and corrosion resistance. However, metallurgical defects such as segregation and inclusions are prone to occur during the smelting process. During press working and heat treatment during the production of titanium alloy bars, internal cracks and holes can form due to differences in mechanical properties between the metallurgical defects and the matrix.

[0003] Ultrasonic flaw detection technology offers the advantages of high sensitivity, non-destructive testing, and rapid speed, making it effective in detecting defects within titanium alloy bars. Titanium alloy products have complex multiphase and polycrystalline structures, as well as varying grain orientations. These differences in microstructure and structure occur in different parts of the product, leading to abnormal signals during ultrasonic testing, such as increased noise levels and attenuated background wave intensity. These abnormal signals can be misinterpreted as defects, affecting the stability of the ultrasonic detection signal and resulting in inaccurate flaw detection results for titanium alloy bars. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of this application is to provide a method and system for ultrasonic flaw detection of titanium alloy bars. The technical solutions adopted are as follows:

[0005] In a first aspect, an embodiment of the present application provides a method for ultrasonic flaw detection of a titanium alloy bar, the method comprising the following steps:

[0006] Obtain ultrasonic signals at various positions of the titanium alloy bar;

[0007] The reception time sequence of each location is obtained based on the time interval between each signal transmission and reception in the ultrasonic signal at each location; all peaks in each ultrasonic signal are obtained; the anisotropy significance of each location is obtained based on the difference between adjacent peaks in the ultrasonic signal at each location and the degree of dispersion of all peaks, and the actual defectivity of each location is obtained by combining the average level of the reception time sequence of each location and the difference between the reception time sequence of each location and adjacent locations;

[0008] Decompose each ultrasonic signal into multiple modal components; obtain the signal complexity of each position based on the discrete degree of the amplitude average level of all modal components corresponding to the ultrasonic signal at each position, as well as the total number of modal components; and obtain the signal anomaly factor of each position based on the discrete degree of energy corresponding to all high-frequency components in the frequency domain of the ultrasonic signal at each position, as well as the bandwidth difference between each high-frequency component and the non-high-frequency component;

[0009] The defect factor of each position is obtained based on the actual defectivity and signal anomaly factor of each position; and whether there is a defect at each position is determined based on the defect factor of each position.

[0010] Preferably, the reception duration sequence of each position is obtained as follows: the time taken from transmission to reception of each signal in the ultrasonic signal corresponding to each position is used as the reception duration of each signal in the ultrasonic signal corresponding to each position; the reception durations of all signals in the ultrasonic signal corresponding to each position are arranged into a sequence in ascending order, which is recorded as the reception duration sequence of each position.

[0011] Preferably, the calculation formula for the anisotropy significance at each position is: Where, is the anisotropic saliency of the ith position, is the cumulative result of the difference between each peak and the next peak in the peak sequence at the i-th position, is the approximate entropy of the peak sequence at the ith position, and exp( ) is an exponential function with the natural constant e as the base.

[0012] Preferably, the peak sequence at the i-th position refers to a sequence composed of all peak values ​​in the ultrasonic signal at the i-th position in a time sequence.

[0013] Preferably, the calculation formula for the true defectivity of each position is: Where, is the true defectivity of the ith position, is the average value of all data in the reception duration sequence of the i-th position, is the cumulative result of the DTW distance between the reception time sequence of the i-th position and the reception time sequences of its neighboring positions, is the anisotropy significance of the ultrasonic signal at the ith position, norm( ) is the normalization function; where the neighborhood positions of each position refer to the two positions closest to each position in the spiral detection trajectory.

[0014] Preferably, the signal complexity of each position is obtained by calculating the variance of the amplitude mean of all modal components corresponding to the ultrasonic signal at each position of the titanium alloy rod, and taking the product of the total number of all modal components corresponding to the ultrasonic signal at the i-th position and the variance as the signal complexity of the i-th position.

[0015] Preferably, the calculation formula for the signal anomaly factor at each position is: Where, is the signal anomaly factor at the ith position, exp( ) is an exponential function with the natural constant e as the base, is the variance of the energy corresponding to all high-frequency components of the ultrasonic signal at the i-th position, is the cumulative difference between each high-frequency component of the ultrasonic signal at the i-th position and the 3dB bandwidth of all other non-high-frequency components. is the signal complexity of the ith position, is a preset constant.

[0016] Preferably, the defect factor of each position is a forward fusion result of the real defectivity and signal abnormality factor of each position.

[0017] Preferably, the specific process of judging whether there are defects at each position is: when the defect factor at a single position of the titanium alloy rod is less than a preset threshold, it is judged that there are no defects inside the titanium alloy rod at that position; otherwise, it is judged that there are defects inside the titanium alloy rod at that position.

[0018] In the second aspect, an embodiment of the present application also provides an ultrasonic flaw detection system for titanium alloy bars, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above-mentioned ultrasonic flaw detection methods for titanium alloy bars are implemented.

[0019] This application has at least the following beneficial effects:

[0020] 1. This application constructs the real defects at each position by analyzing the distinctive features of the ultrasonic signals caused by the anisotropy of the elastic modulus and the real defects inside the titanium alloy bar. It can effectively avoid the disadvantages of abnormal signals such as abnormal ultrasonic propagation speed, increased clutter level and attenuation of background intensity caused by the anisotropy of the elastic modulus inside the titanium alloy bar being misjudged as defect signals, thereby improving the accuracy of ultrasonic flaw detection of titanium alloy bars.

[0021] 2. Compared with traditional ultrasonic detection technology for titanium alloy products, this application does not need to construct complex energy distribution cloud maps. It can quickly analyze and obtain abnormal ultrasonic signal conditions caused by real defects inside titanium alloy bars by relying only on ultrasonic signal characteristics. By constructing defect factors at each position to characterize the degree of defects inside the titanium alloy bar, it can more accurately evaluate the real internal defect conditions at each position of the titanium alloy bar. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 A flowchart of a method for ultrasonic flaw detection of titanium alloy bars provided in one embodiment of the present application;

[0024] Figure 2 A flowchart for obtaining defect factors at various locations is provided for one embodiment of the present application. DETAILED DESCRIPTION

[0025] To further illustrate the technical means and effectiveness of this application's implementation of the intended invention, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail the specific implementation, structure, features, and effectiveness of a method and system for ultrasonic flaw detection of titanium alloy bars proposed in this application. In the following description, references to different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0026] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0027] The following describes in detail a method and system for ultrasonic flaw detection of titanium alloy bars provided by the present application with reference to the accompanying drawings.

[0028] See also Figure 1 , which shows a flowchart of a method for ultrasonic flaw detection of titanium alloy bars provided by one embodiment of the present application, the method comprising the following steps:

[0029] Step 1: Obtain ultrasonic signals at various locations on the titanium alloy bar.

[0030] This embodiment uses a pulse detection method to collect relevant data during the ultrasonic flaw detection process of titanium alloy bars. Specifically, the titanium alloy bar is set to rotate along the bar axis at a linear speed of 10m / min and move horizontally. The titanium alloy bar is spirally detected by the ultrasonic probe of a digital ultrasonic sonicator. The function of the ultrasonic probe is to transmit and receive ultrasonic signals. The ultrasonic probe emits a high-frequency pulse every t seconds, corresponding to an ultrasonic wavelength of 1.2mm. Each time the probe emits a high-frequency pulse, it corresponds to a different position of the titanium alloy bar. After each high-frequency pulse is emitted, the ultrasonic probe is used to receive the ultrasonic signal returned from each titanium alloy bar position (all echo signals of each position of the titanium alloy bar in the depth direction), and the ultrasonic signal of each position of the titanium alloy bar in the spiral detection track is obtained. In this embodiment, t is 0.5.

[0031] The ultrasonic signals at each position are used as input to the wavelet transform algorithm for denoising, in order to prevent the external environment noise from seriously affecting the subsequent analysis. The wavelet transform algorithm is a well-known technology, and the specific process will not be described in detail.

[0032] At this point, ultrasonic signals at various locations in the titanium alloy rod can be obtained.

[0033] Step 2: Obtain the reception time sequence of each position based on the time interval between the transmission and reception of each signal in the ultrasonic signal of each position; obtain all peaks in each ultrasonic signal; obtain the anisotropy significance of each position based on the difference between adjacent peaks in the ultrasonic signal of each position and the degree of dispersion of all peaks, and combine the average level of the reception time sequence of each position and the difference between the reception time sequence of each position and the adjacent positions to obtain the true defectivity of each position.

[0034] During the ultrasonic flaw detection process of titanium alloy bars, the propagation of ultrasonic signals in the titanium alloy bars is affected by the anisotropy of the elastic modulus of the close-packed hexagonal structure crystal, resulting in different propagation rates of ultrasonic waves in grains with different orientations, and the resulting ultrasonic clutter signals and background attenuation conditions are also different; and real defects such as cracks, pores and inclusions inside the titanium alloy bars will also cause abnormal ultrasonic signals.

[0035] Specifically, real defects inside the titanium alloy rod will cause the energy of the ultrasonic wave to attenuate, thereby slowing down the propagation speed of the ultrasonic signal and increasing the propagation time; and the elastic modulus anisotropy will cause the ultrasonic signal wave velocity to differ with the propagation direction, that is, when the ultrasonic wave propagation direction is aligned with the crystal structure axis of the titanium alloy, the ultrasonic signal propagation speed is faster, and when the ultrasonic wave propagation direction is perpendicular to the crystal structure axis, the wave velocity is lower; the crystal orientation of adjacent positions in the titanium alloy rod changes smoothly, and usually has a continuous crystal orientation.

[0036] Secondly, the real defects inside the titanium alloy will significantly scatter and absorb ultrasonic sound energy, thereby generating sharp and steep main reflection waves, while the elastic modulus anisotropy will produce relatively smooth low-amplitude noise; because the real defect area inside the titanium alloy bar absorbs and scatters ultrasonic energy more strongly than the elastic modulus anisotropy, the ultrasonic signal attenuation rate caused by the real defects inside the titanium alloy bar is higher, and the ultrasonic signal attenuation trend caused by the elastic modulus anisotropy is more stable and slow.

[0037] The two closest locations to each position in the spiral detection trajectory are considered the neighboring locations of each position. The duration from transmission to reception of each signal in the ultrasonic signal corresponding to each position is used as the reception duration of each signal in the ultrasonic signal corresponding to each position (internal defects and grain structure of titanium alloy bars can cause ultrasonic wave scattering and diffraction, resulting in multiple signals being returned). The reception durations of all signals in the ultrasonic signal corresponding to each position are arranged in ascending order and recorded as the reception duration sequence for each position.

[0038] The ultrasonic signal corresponding to each position in the spiral inspection trajectory of titanium alloy bars is taken as input. The AMPD (Automatic Multiscale-based Peak Detection) peak detection algorithm is used to obtain all peaks in each ultrasonic signal. The sequence of all peaks in the ultrasonic signal at each position in time sequence is recorded as the peak sequence at each position.

[0039] As a preferred embodiment, the anisotropy significance of each position is obtained according to the difference between adjacent peaks in the ultrasonic signal at each position and the degree of dispersion of all peaks.

[0040] In this embodiment, the anisotropy significance of the ultrasonic signal at the i-th position in the titanium alloy bar is recorded as , its specific expression is: Where, is the anisotropic saliency of the ith position, is the cumulative result of the difference between each peak and the next peak in the peak sequence at the i-th position (it should be noted that there is no peak after the last peak, so the difference of the last peak is not calculated). is the approximate entropy of the peak sequence at the ith position, and exp( ) is an exponential function with the natural constant e as the base.

[0041] The sharp and steep reflection waves of ultrasonic signals caused by real internal defects and the smooth attenuation of ultrasonic signals are characterized. The larger the value of , the more likely the ultrasonic signal at the i-th position is a signal caused by elastic modulus anisotropy.

[0042] Furthermore, as a preferred embodiment, based on the anisotropy significance of each position, combined with the average level of the reception time sequence of each position, and the difference between the reception time sequence of each position and the adjacent positions, the real defectivity of each position is obtained, which is used to characterize the possibility that the signal in each time period of the ultrasonic signal is caused by a real defect inside the titanium alloy bar.

[0043] In this embodiment, the true defectivity of the i-th position in the titanium alloy bar is recorded as , its specific expression is: Where, is the true defectivity of the ith position, is the average value of all data in the reception duration sequence of the i-th position, is the cumulative result of the DTW distance between the reception time sequence of the i-th position and the reception time sequences of its neighboring positions, is the anisotropy significance of the ultrasonic signal at the ith position, norm( ) is the normalization function, so that The value range of is between [0, 1]. In this embodiment, the sigmoid function is used for normalization.

[0044] It reflects the slowness of the ultrasonic signal of titanium alloy bar; reflects the orientation difference between the i-th position and the adjacent positions, The larger the value is, the more likely it is that there is a defect at the i-th position. The larger the value of , the slower the ultrasonic signal velocity at the i-th position, the greater the difference in ultrasonic velocity caused by the continuous crystal orientation at adjacent positions, the more significant the difference in ultrasonic detection signal peaks, and the worse the stability of the ultrasonic peak value change. In this case, the abnormal ultrasonic signal at this position is more likely to be caused by a real defect inside the titanium alloy bar.

[0045] At this point, the true defectivity of each position in the spiral inspection trajectory of the titanium alloy bar can be obtained through the above method.

[0046] Step 3: Decompose each ultrasonic signal into multiple modal components; obtain the signal complexity of each position based on the discrete degree of the amplitude average level of all modal components corresponding to the ultrasonic signal at each position, as well as the total number of modal components, and combine the discrete degree of energy corresponding to all high-frequency components of the ultrasonic signal at each position in the frequency domain, as well as the bandwidth difference between each high-frequency component and the non-high-frequency component, to obtain the signal anomaly factor at each position.

[0047] During the ultrasonic flaw detection process of titanium alloy bars, the difference in acoustic impedance of the internal component segregation area (such as hard α defects) of the titanium alloy bars will cause the transmission loss of sound energy. In addition, the difference in acoustic impedance between the real defects inside the product and the matrix structure is large, which will cause the ultrasonic waves to be strongly reflected at the defects. Not only will high-amplitude reflected echoes be generated, but the scattering and diffraction of ultrasonic waves at the internal defects of the titanium alloy will cause more reflection paths, and will also aggravate the distribution complexity of the ultrasonic signal in different frequency components.

[0048] Specifically, real defects inside titanium alloys will cause the energy distribution of all frequency components in the ultrasonic echo signal to be more complex, and there are a large number of high-frequency components in the ultrasonic signal generated by real defects. These high-frequency components show higher energy concentration and wider frequency spectrum characteristics in the frequency domain; in addition, the increase in ultrasonic scattering and diffraction paths will further aggravate the signal distribution complexity of the ultrasonic signal, that is, the more obvious the difference between the various modal components after the decomposition of the ultrasonic signal of the titanium alloy bar, the stronger the discreteness of the energy distribution in each modal component.

[0049] Based on the above analysis, this application constructs a signal anomaly factor to characterize the degree of ultrasonic signal anomaly caused by internal defects in titanium alloy bars. The ultrasonic signal corresponding to each position in the spiral detection trajectory of the titanium alloy bar is used as input, and the FFT fast Fourier transform and EMD (Empirical Mode Decomposition) empirical mode decomposition algorithms are used to obtain the frequency domain representation of the ultrasonic signal at each position and the various modal components corresponding to the ultrasonic signal. The frequencies of all frequency components of the ultrasonic signal in the frequency domain representation are sorted in descending order, and the first p frequency components are selected and recorded as the high-frequency components of the ultrasonic signal (p is 10 in this embodiment). The 3dB bandwidth of the ultrasonic signal at each position corresponding to all frequency components in the frequency domain is calculated.

[0050] The mean of all amplitudes corresponding to each modal component obtained after decomposing the ultrasonic signal is used as the mean amplitude value of each modal component. The greater the difference in the mean amplitude values ​​between the modal components, the greater the discreteness of the ultrasonic signal's energy distribution across all modal components.

[0051] Calculate the variance of the mean amplitude of all modal components corresponding to the ultrasonic signal at the i-th position in the titanium alloy bar. Multiply the total number of modal components corresponding to the ultrasonic signal at the i-th position by the variance to determine the signal complexity at that position. Signal complexity represents the degree of signal complexity caused by real defects within the titanium alloy.

[0052] As a preferred embodiment, based on the signal complexity of each position, combined with the discrete degree of energy corresponding to all high-frequency components of the ultrasonic signal at each position in the frequency domain, and the bandwidth difference between each high-frequency component and the non-high-frequency component, the signal anomaly factor at each position is obtained to characterize the abnormal condition of the ultrasonic signal caused by the real defects inside the titanium alloy bar and the complexity of the signal distribution.

[0053] In this embodiment, the signal anomaly factor at the i-th position in the titanium alloy bar is recorded as , its specific expression is: Where, is the signal anomaly factor at the ith position, exp( ) is an exponential function with the natural constant e as the base, is the variance of the energy corresponding to all high-frequency components of the ultrasonic signal at the i-th position, is the cumulative difference between each high-frequency component of the ultrasonic signal at the i-th position and the 3dB bandwidth of all other non-high-frequency components. is the signal complexity of the ith position, is a preset constant used to prevent the denominator from being 0. In this embodiment, it is set to 0.01;

[0054] and They respectively reflect the high-frequency component energy concentration and bandwidth caused by the internal defects of the titanium alloy bar; when the real defects inside the titanium alloy bar are more serious, the high-frequency component energy concentration of the ultrasonic signal is stronger, that is, the index The smaller it is, the larger the spectrum bandwidth of the high-frequency component is, that is, the index The larger the value, the more complex the ultrasonic signal components are, the larger the total number of modal components is, and the more uneven the energy distribution of the frequency components corresponding to each modal component is. Get bigger.

[0055] Step 4: Obtain the defect factor of each position based on the actual defectivity and signal anomaly factor of each position; determine whether there is a defect at each position based on the defect factor of each position.

[0056] The more likely the ultrasonic signals at various locations in the titanium alloy bar are to be caused by real defects rather than elastic modulus anisotropy, and the greater the abnormality of the ultrasonic signals, the more obvious the real defects inside the titanium alloy bar are, and the more serious the impact on the quality of the titanium alloy bar is.

[0057] As a preferred embodiment, the defect factor of each position is obtained based on the real defectivity and signal abnormality factor of each position, which is used to characterize the internal defect conditions at each position of the titanium alloy bar. The acquisition process of the defect factor of each position is as follows: Figure 2 shown.

[0058] In this embodiment, the normalized result of the product of the signal abnormality factor and the actual defectivity at the i-th position is used as the defect factor at the i-th position.

[0059] In another embodiment, a normalized result of the cumulative sum of the signal anomaly factor and the actual defectivity at the i-th position is used as the defect factor at the i-th position.

[0060] When the defect factor at the i-th position is larger, it means that the ultrasonic signal at this position is more likely to be caused by a real defect inside the titanium alloy bar rather than anisotropy of the elastic modulus, and the more obvious the abnormal condition of the ultrasonic signal caused by the internal defect of the titanium alloy bar is, the more serious the real internal defect of the titanium alloy bar at the i-th position is.

[0061] Furthermore, when the defect factor at a single location on the titanium alloy bar is less than a preset threshold, the titanium alloy bar at that location is judged to be free of defects; otherwise, the titanium alloy bar at that location is judged to have defects. In this embodiment, the preset threshold is 0.6, and the implementer can adjust the preset threshold value according to actual conditions.

[0062] The presence of defects at all locations on the titanium alloy bar is determined. If the total number of locations with defects in the titanium alloy bar is greater than or equal to a preset proportion of the total number of locations, the titanium alloy bar is judged to be unqualified, and a marking unit sprays an unqualified mark on the surface of the titanium alloy bar. Otherwise, the titanium alloy bar is judged to be qualified. In this embodiment, the preset ratio is 1 / 3, and the implementer can set the preset ratio according to actual conditions.

[0063] Thus, a method for ultrasonic flaw detection of titanium alloy bars can be realized.

[0064] Based on the same inventive concept as the above-mentioned method, an embodiment of the present application also provides an ultrasonic flaw detection system for titanium alloy bars, comprising a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of any one of the above-mentioned ultrasonic flaw detection methods for titanium alloy bars are implemented.

[0065] It should be noted that the order in which the embodiments of the present application are presented is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. Furthermore, the foregoing descriptions of specific embodiments of this specification are provided. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential sequence shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0066] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0067] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for ultrasonic flaw detection of titanium alloy bars, characterized in that: The method comprises the following steps: Obtain ultrasonic signals at various positions of the titanium alloy bar; The reception time sequence of each position is obtained based on the time interval between the transmission and reception of each signal in the ultrasonic signal at each position; all peaks in each ultrasonic signal are obtained; the anisotropy significance of each position is obtained based on the difference between adjacent peaks in the ultrasonic signal at each position and the degree of dispersion of all peaks, and the actual defectivity of each position is obtained by combining the average level of the reception time sequence of each position and the difference between the reception time sequence of each position and the adjacent positions; the calculation formula of the anisotropy significance of each position is: Where, is the anisotropic saliency of the i-th position, is the cumulative result of the difference between each peak and the next peak in the peak sequence at the i-th position, is the approximate entropy of the peak sequence at the ith position, exp( ) is an exponential function with the natural constant e as the base; the calculation formula for the true defectivity at each position is: Where, is the true defectivity of the ith position, is the average value of all data in the reception duration sequence of the i-th position, is the cumulative result of the DTW distance between the reception time sequence of the i-th position and the reception time sequences of its neighboring positions, is the anisotropy significance of the ultrasonic signal at the i-th position, norm( ) is the normalization function; where the neighborhood positions of each position refer to the two positions closest to each position in the spiral detection trajectory; Each ultrasonic signal is decomposed into multiple modal components; the signal complexity of each position is obtained based on the discrete degree of the amplitude average level of all modal components corresponding to the ultrasonic signal at each position and the total number of modal components, and the signal anomaly factor of each position is obtained by combining the discrete degree of the energy corresponding to all high-frequency components of the ultrasonic signal at each position in the frequency domain and the bandwidth difference between each high-frequency component and the non-high-frequency component; the signal complexity of each position is obtained by calculating the variance of the amplitude mean of all modal components corresponding to the ultrasonic signal at each position of the titanium alloy bar, and taking the product of the total number of all modal components corresponding to the ultrasonic signal at the i-th position and the variance as the signal complexity of the i-th position; the calculation formula of the signal anomaly factor at each position is: Where, is the signal anomaly factor at the ith position, exp( ) is an exponential function with the natural constant e as the base, is the variance of the energy corresponding to all high-frequency components of the ultrasonic signal at the i-th position, is the cumulative difference between each high-frequency component of the ultrasonic signal at the i-th position and the 3dB bandwidth of all other non-high-frequency components. is the signal complexity of the ith position, is a preset constant; The defect factor of each position is obtained based on the actual defectivity and signal anomaly factor of each position. The defect factor of each position is the forward fusion result of the actual defectivity and signal anomaly factor of each position. The presence of a defect at each position is determined based on the defect factor of each position.

2. The ultrasonic flaw detection method for titanium alloy bars according to claim 1, characterized in that: The method for obtaining the reception duration sequence of each position is as follows: the time taken from transmission to reception of each signal in the ultrasonic signal corresponding to each position is used as the reception duration of each signal in the ultrasonic signal corresponding to each position; the reception durations of all signals in the ultrasonic signal corresponding to each position are arranged into a sequence in ascending order, which is recorded as the reception duration sequence of each position.

3. The ultrasonic flaw detection method for titanium alloy bars according to claim 1, characterized in that: The peak sequence at the i-th position refers to a sequence consisting of all peak values ​​in the ultrasonic signal at the i-th position in a time sequence.

4. The ultrasonic flaw detection method for titanium alloy bars according to claim 1, characterized in that: The specific process of judging whether there are defects at each position is as follows: when the defect factor at a single position of the titanium alloy rod is less than a preset threshold, it is judged that there are no defects inside the titanium alloy rod at that position; otherwise, it is judged that there are defects inside the titanium alloy rod at that position.

5. A titanium alloy bar ultrasonic flaw detection system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the titanium alloy bar ultrasonic flaw detection method according to any one of claims 1 to 4 are implemented.

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