Ultrasonic stress detection influence factor correction method suitable for underwater environment

Abstract

The invention provides an ultrasonic stress detection influence factor correction method suitable for an underwater environment, and the method comprises the steps: making an experiment scheme for a tested piece, and determining an experiment scheme of an underwater stress detection device; deploying the underwater stress detection device according to the experimental scheme of the underwater stress detection device; carrying out an underwater stress detection temperature influence sound velocity correction experiment on the tested piece through the underwater stress detection device to obtain ultrasonic sound time values at different temperatures; performing underwater ultrasonic stress detection influence factor analysis according to an experimental result; according to an analysis result, proposing an underwater ultrasonic stress detection influence factor correction formula, and correcting the underwater ultrasonic stress detection influence factor; according to the invention, the ultrasonic stress detection technology is applied to the underwater environment, the temperature influence factors existing in the ultrasonic stress underwater environment detection process are tested, correction parameters are obtained, and the deviation of underwater structure stress detection is reduced, so that the accuracy of underwater environment stress detection is improved.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic stress detection, and particularly to a method for correcting influence factors of ultrasonic stress detection applicable to underwater environments. Background Art

[0002] The ultrasonic stress detection technology is based on the acoustoelastic principle. When the transmitting transducer emits ultrasonic longitudinal waves and obliquely incident on the surface of the material to be inspected at the first critical angle, according to Snell's law, critical refracted longitudinal waves can be generated inside the material to be inspected. The stress in the material will affect the ultrasonic wave propagation speed. When the stress direction is consistent with the ultrasonic wave propagation direction, tensile stress slows down the ultrasonic wave propagation speed or prolongs the propagation time, and compressive stress speeds up the ultrasonic wave propagation speed or shortens the propagation time; Therefore, under the condition that the distance between the transmitting and receiving transducers remains unchanged, the ultrasonic wave propagation time corresponding to zero stress and the ultrasonic wave propagation time corresponding to the workpiece to be inspected are measured, and the absolute value of the stress in the workpiece to be inspected can be obtained; Since the underwater environment is different from the onshore environment, there are problems such as temperature, pressure, and long-distance signal transmission. If the calibration detection is carried out according to the onshore process, there will be certain deviations and the true stress level of the workpiece cannot be reflected; Therefore, the present invention proposes a method for correcting influence factors of ultrasonic stress detection applicable to underwater environments in view of the influence of temperature on ultrasonic stress detection. The ultrasonic stress detection technology is applied to underwater environments, and experiments are carried out on the temperature influence factors existing in the process of ultrasonic stress underwater environment detection to obtain correction parameters, optimize the equipment calibration and detection processes, reduce the deviations occurring in underwater structure stress detection, and thus improve the accuracy of underwater environment stress detection. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for correcting influence factors of ultrasonic stress detection applicable to underwater environments to solve the problems appearing in the above background art.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A method for correcting influence factors of ultrasonic stress detection applicable to underwater environments, including: Step 1: Formulate an experimental plan for the test piece to be tested and determine the experimental plan of the underwater stress detection device; Step 2: Deploy the underwater stress detection device according to the experimental plan of the underwater stress detection device; Step 3: Conduct an experiment on correcting the sound velocity affected by temperature of underwater stress detection for the test piece to be tested through the underwater stress detection device to obtain the ultrasonic wave sound time values at different temperatures; Step 4: Analyze the influence factors of underwater ultrasonic stress detection according to the results of the experiment; Step 5: Based on the analysis results of the influencing factors for underwater ultrasonic stress detection, propose a correction formula for the influencing factors of underwater ultrasonic stress detection and correct the underwater ultrasonic stress value.

[0005] Further, in Step 3, the test piece is a plate specimen of structural steel for ships and ocean engineering; In Step 1, formulating the experimental plan for the test piece includes proposing important influencing factors that may affect underwater ultrasonic stress detection and formulating an experimental plan for correcting the sound velocity affected by the underwater stress detection temperature. The important influencing factor is temperature.

[0006] Further, in Step 2, the underwater stress detection device includes an ultrasonic residual stress detection host, a stress detection probe configured to cooperate with the ultrasonic residual stress detection host, and a signal transmission cable configured to cooperate with the ultrasonic residual stress detection host.

[0007] Further, the ultrasonic residual stress detection host includes a host shell, a display screen, a power supply and a probe interface, an operating system and application software. The display screen is used for detection operations and displays the ultrasonic signal amplitude value, the ultrasonic wave propagation time, and the stress value of the workpiece under inspection.

[0008] Further, the stress detection probe includes a transmitting transducer, a receiving transducer configured to cooperate with the transmitting transducer, and a wedge block disposed between the transmitting transducer and the receiving transducer.

[0009] Further, the ultrasonic residual stress detection host, the stress detection probe, and the signal transmission cable are models produced by domestic manufacturers.

[0010] Further, in Step 3, the temperature range is 0°C to 50°C; In Step 3, at least 5 different temperature values are selected and the difference between the highest and lowest temperatures is at least 15°C; The underwater stress detection temperature affecting the sound velocity correction experiment in Step 3 includes: S1. Define the experimental scenario. The experimental scenario should include the experimental site, the environmental water depth, and the environmental temperature. Place the test piece in different temperature environments at the same water depth, and use the ultrasonic residual stress detection host to generate an excitation electrical signal; S2. The electrical signal is transmitted through the signal transmission cable to the transmitting transducer of the stress detection probe. The transmitting transducer excites an ultrasonic critically refracted longitudinal wave. The critically refracted longitudinal wave passes through the test piece and is received by the receiving transducer, and the ultrasonic critically refracted longitudinal wave signal is converted into an excitation electrical signal again; S3. The signal transmission cable transmits the signal back to the ultrasonic residual stress detection host, and the ultrasonic wave travel time in the same water depth and different temperature environments is obtained through the ultrasonic residual stress detection host. Since the propagation distance of the ultrasonic wave in the test piece remains unchanged, the change in the ultrasonic wave velocity can be reflected by the change in the travel time.

[0011] Further, the experimental result in Step 4 is the experimental data obtained from the underwater stress detection temperature influence on sound velocity correction experiment; The analysis of the influencing factors of underwater ultrasonic stress detection in Step 4 is to analyze the change of the ultrasonic wave travel time value under different temperature environments.

[0012] Further, the correction of the influencing factors of underwater ultrasonic stress detection in Step 5 is to propose a correction formula for the influencing factors of underwater ultrasonic stress detection according to the experimental data results under different temperature environments, and correct the underwater ultrasonic stress value.

[0013] Further, the derivation process of the correction formula for the influencing factors of underwater ultrasonic stress detection in Step 5 is as follows: According to the ultrasonic detection principle, when the ultrasonic wave is incident on the surface of the inspected material at the first critical angle, according to Snell's law, a critical refracted longitudinal wave can be generated inside the inspected material. According to the acoustoelastic principle, the residual stress in the material will affect the ultrasonic wave propagation speed. When the residual stress direction is consistent with the ultrasonic wave propagation direction, the tensile stress slows down the ultrasonic wave propagation speed or prolongs the propagation time t and the compressive stress speeds up the ultrasonic wave propagation speed or shortens the propagation time t. Therefore, under the condition that the acoustic path distance remains unchanged, if the ultrasonic wave propagation time σ 0 corresponding to zero stress t 0 and the ultrasonic wave propagation time t corresponding to the inspected workpiece are measured, the residual stress value in the inspected workpiece can be calculated, that is: σ - σ 0 = K(t - t 0 ) Or ∆σ = ΚΔt In the formula: ∆σ —— The change amount of residual stress (stress difference), ∆σ = σ - σ 0 Δt —— The change amount of ultrasonic wave propagation time (time difference of sound), Δt = (t - t 0 ) Κ —— The stress coefficient, which is related to the material to be inspected and the probe spacing, can be obtained through calibration in a tensile test.

[0014] According to the thermoelastic theory, within a certain temperature range, the propagation speed (acoustic time) of longitudinal ultrasonic waves in a medium has an approximately linear relationship with temperature. From the above stress formula, it can be seen that stress also has a linear relationship with acoustic time. Therefore, the stress correction formula caused by temperature difference is as follows: σ(T) = C*(T 1 -T 0 ） / K C = (t max -t min ) / (T max -T min ) In the formula: σ(T) is the stress correction value caused by temperature change; T 1 is the temperature of the workpiece to be measured; T 0 is the temperature for zero-stress acoustic time calibration of the zero-stress test block; C is the temperature correction coefficient, which can be obtained through temperature correction experiments; t max and t min are the maximum and minimum acoustic times during the temperature correction experiment; T max and T min are the highest and lowest water temperatures during the temperature correction experiment; K is the stress calibration coefficient of the workpiece to be measured, that is, the slope of the test acoustic time difference and the stress value; Therefore, the actual stress of the workpiece to be measured should be: σ(real) = ΚΔt + σ(T).

[0015] Through the above technical solution, the beneficial effects of the present invention are: The present invention provides a method for correcting influencing factors in ultrasonic stress detection applicable to underwater environments. An experimental plan is formulated for the test piece to determine the experimental plan of the underwater stress detection device; the underwater stress detection device is deployed according to the experimental plan of the underwater stress detection device; an experiment for correcting the influence of temperature on the sound velocity in underwater stress detection is carried out on the test piece through the underwater stress detection device to obtain the ultrasonic sound time values at different temperatures; according to the experimental results, an analysis of the influencing factors in underwater ultrasonic stress detection is carried out; according to the analysis results, a correction formula for the influencing factors in underwater ultrasonic stress detection is proposed to correct the influencing factors in underwater ultrasonic stress detection, obtain correction parameters, optimize the equipment calibration and detection processes, reduce the deviation in underwater structural stress detection, and thus improve the accuracy of underwater environmental stress detection.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0017] The following drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the following specific embodiments to explain the present invention, but the protection scope of the present invention is not limited to the following drawings and specific embodiments. In the drawings: Figure 1 is a flowchart of a method for correcting influencing factors in ultrasonic stress detection applicable to underwater environments according to the present invention; Figure 2 is a schematic diagram of the principle of transmitting and receiving ultrasonic critically refracted longitudinal wave signals; Figure 3 is a schematic diagram of the detection area of the present invention. Specific Embodiments

[0018] The following details the specific embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0019] First of all, it should be noted that in the description of the following technical solutions of the present invention, the orientation terms "inside", "outside", "bottom", "below", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0020] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "connection", "installation", and "fixation" should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium, and can be the connection inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] Referring to the accompanying drawings Figure 1 , an embodiment of the present invention provides a method for correcting influencing factors of ultrasonic stress detection applicable to an underwater environment, including: Step 1: Formulate an experimental plan for the test piece to determine the experimental plan of the underwater stress detection device; Step 2: Deploy the underwater stress detection device according to the experimental plan of the underwater stress detection device; Step 3: Conduct an experiment on correcting the sound velocity affected by temperature for underwater stress detection of the test piece through the underwater stress detection device to obtain the ultrasonic sound time values at different temperatures; Step 4: Analyze the influencing factors of underwater ultrasonic stress detection according to the experimental results; Step 5: According to the analysis results of the influencing factors of underwater ultrasonic stress detection, propose a correction formula for the influencing factors of underwater ultrasonic stress detection and correct the underwater ultrasonic stress value.

[0022] In the present invention, an experimental plan is formulated for the test piece to determine the experimental plan of the underwater stress detection device; the underwater stress detection device is deployed according to the experimental plan of the underwater stress detection device; an experiment on correcting the sound velocity affected by temperature for underwater stress detection of the test piece is conducted through the underwater stress detection device, and according to the experimental results, the influencing factors of underwater ultrasonic stress detection are analyzed; according to the analysis results, a correction formula for the influencing factors of underwater ultrasonic stress detection is proposed, the influencing factors of underwater ultrasonic stress detection are corrected to obtain correction parameters, the equipment calibration and detection process are optimized, and the deviation in underwater structural stress detection is reduced, thereby improving the accuracy of underwater environment stress detection.

[0023] Preferably, referring to the accompanying drawings Figure 1 and Figure 2, in Step 3, the test piece is a plate specimen of ship and ocean engineering structural steel; in Step 1, formulating the experimental plan for the test piece includes identifying the important influencing factors that may affect underwater ultrasonic stress detection and formulating an experimental plan for correcting the sound velocity affected by the temperature of underwater stress detection. The important influencing factor is temperature. More preferably, the test piece is selected with the model number DH36, 310mm×65mm×19mm. In the specific implementation, the change in temperature will cause changes in the elastic modulus and density of the object. When the temperature rises, the elastic modulus and density of the object will decrease, thereby causing changes in the sound velocity. According to the thermoelastic theory, within a certain temperature range, the propagation velocity of ultrasonic longitudinal waves in the medium has an approximate linear relationship with the temperature: V(T) = V 0 (1-α∆T) In the formula V(T) is the longitudinal wave sound velocity at temperature T without stress, V 0 is the longitudinal wave sound velocity at the initial stress-free temperature, α is the sound velocity coefficient of the longitudinal wave varying with temperature, approximately on the order of 10 -4 magnitude, ∆T is the change in temperature. Therefore, an experiment is conducted with temperature as an important influencing factor affecting the accuracy of underwater ultrasonic stress detection, that is, an experiment for correcting the sound velocity affected by the temperature of underwater stress detection is carried out, and finally the experimental plan of the underwater stress detection device is determined.

[0024] Specifically, the underwater stress detection device includes an ultrasonic residual stress detection host, a stress detection probe configured to cooperate with the ultrasonic residual stress detection host, and a signal transmission cable configured to cooperate with the ultrasonic residual stress detection host; More specifically, the ultrasonic residual stress detection host includes a host housing, a display screen, a power supply and a probe interface, an operating system and application software. The display screen is used for detection operations and displays the ultrasonic signal amplitude value, the ultrasonic wave propagation time, and the stress value of the workpiece to be inspected; specifically, the ultrasonic residual stress detection host is the HS1010 ultrasonic residual stress detector produced by Wuhan Zhongke Innovation Technology Co., Ltd., and the detection time accuracy is 1 ns; Preferably, the stress detection probe includes a transmitting transducer, a receiving transducer configured to cooperate with the transmitting transducer, and a sound wedge block disposed between the transmitting transducer and the receiving transducer. Specifically, the stress detection probe indicates the first critical angle and is the ZKCX-PR-45X stress detection probe produced by Wuhan Zhongke Innovation Technology Co., Ltd., and the first critical angle is 23°.

[0025] See the attached drawings Figure 1 、 Figure 2 and Figure 3, specifically, an underwater stress detection temperature influence sound velocity correction experiment is carried out on the test piece by an underwater stress detection device. The ultrasonic residual stress detection host generates an excitation electrical signal, which is transmitted through a signal transmission cable to the transmitting transducer of the stress detection probe. The transmitting transducer excites an ultrasonic critically refracted longitudinal wave, which passes through the test piece and is received by the receiving transducer, and the ultrasonic critically refracted longitudinal wave signal is converted into an excitation electrical signal again, and is transmitted back to the ultrasonic residual stress detection host through the signal transmission cable. The ultrasonic residual stress detection host displays the amplitude value of the ultrasonic signal. Preferably, the amplitude value of the ultrasonic signal is the percentage of the signal peak displayed by the ultrasonic residual stress detection host on the screen; the ultrasonic critically refracted longitudinal wave is a kind of ultrasonic wave that, according to Snell's law, when ultrasonic waves obliquely incident from a medium with a slower sound velocity to a medium with a faster sound velocity, the ultrasonic waves are refracted and the refraction angle of the ultrasonic waves is equal to 90°. When the distance between the transmitting transducer and the receiving transducer is fixed, that is, the ultrasonic path is fixed, combined with the above linear relationship formula between the ultrasonic propagation velocity and temperature, the acoustic time and temperature also show an approximately linear relationship.

[0026] As a preferred embodiment, the underwater stress detection temperature influence sound velocity correction experimental scheme includes the following: Place the test piece in different temperature environments at the same water depth. Specifically, the temperature is selected from 0 to 50 °C, which is convenient for the experimenter to place the test piece in the water or take it out of the water to prevent being scalded by overheated water or frostbitten by supercooled water. Use the ultrasonic residual stress detection host to generate an excitation electrical signal, which is transmitted through a signal transmission cable to the transmitting transducer of the stress detection probe. The transmitting transducer excites an ultrasonic critically refracted longitudinal wave, which passes through the test piece and is received by the receiving transducer, and the ultrasonic critically refracted longitudinal wave signal is converted into an excitation electrical signal again, and is transmitted back to the ultrasonic residual stress detection host through the signal transmission cable. The ultrasonic residual stress detection host obtains the acoustic time values of ultrasonic waves in different temperature environments at the same water depth. The acoustic time of ultrasonic waves is the propagation time of the critically refracted longitudinal wave in the test piece.

[0027] Specifically, an underwater stress detection temperature influence sound velocity correction experiment is carried out on the test piece by an underwater stress detection device. More specifically, the selected experimental scenario is a bucket made of PVC material, 50 cm high and 40 cm in diameter. The water in the bucket is seawater, which is taken from the vicinity of the SZ36-1WHPB oil production platform in the Liaodong Bay of the Bohai Sea. The water depth of the bucket is 25 cm, the initial water temperature is 5 °C, and after a short heating, the water temperature is 35 °C. The length of the cable selected for the experiment is 50 meters. Let the water temperature cool naturally with the air temperature. Starting from 35 °C, the acoustic time value is recorded every time the water temperature drops 3 °C until it drops to 8 °C. The experimental data that can be obtained through the above experiment are as follows:

[0028] Based on the above basic embodiment of the present invention, an analysis of the influencing factors of underwater ultrasonic stress detection is carried out. Specifically, the variation of the ultrasonic acoustic time value is analyzed under the same water depth and different temperature environments.

[0029] An analysis of the influencing factors of underwater ultrasonic stress detection is carried out according to the data results of the above experiments. For the experiment on the influence of temperature on the correction of sound velocity in underwater stress detection, the acoustic time is relatively sensitive to temperature changes. When the water temperature drops from 35°C to 8°C, the temperature difference is 27°C, the acoustic time difference is 15 ns, and the average change rate of sound velocity with temperature is 15÷27 = 0.56 ns / °C. Therefore, it is necessary to correct the change in sound velocity caused by temperature and the resulting change in the stress displayed by the device. Specifically, according to the analysis results of the influencing factors of underwater ultrasonic stress detection, corrections for the influencing factors of underwater ultrasonic stress detection are made. The relevant principles and formula derivation processes are as follows: According to the ultrasonic detection principle, when ultrasonic waves are incident on the surface of the material to be inspected at the first critical angle, according to Snell's law, a critical refracted longitudinal wave can be generated inside the material to be inspected. According to the acoustoelastic principle, the residual stress in the material will affect the ultrasonic wave propagation speed. When the direction of the residual stress is consistent with the ultrasonic wave propagation direction, tensile stress slows down the ultrasonic wave propagation speed or prolongs the propagation time t t, and compressive stress speeds up the ultrasonic wave propagation speed or shortens the propagation time t. Therefore, under the condition that the distance between the transmitting and receiving probes remains unchanged, if the ultrasonic wave propagation time σ 0 corresponding to zero stress t 0 and the ultrasonic wave propagation time t corresponding to the workpiece to be inspected are measured, the residual stress value in the workpiece to be inspected can be obtained, that is: σ - σ 0 = K(t - t 0 ) Or ∆σ = ΚΔt In the formula: ∆σ —— The change amount of residual stress (stress difference), ∆σ = σ - σ 0 Δt —— The change amount of ultrasonic wave propagation time (acoustic time difference), Δt = (t - t 0 ) Κ —— The stress coefficient, which is related to the material to be inspected and the probe spacing, can be obtained through tensile test calibration.

[0030] See the attached drawingsFigure 2 and Figure 3 , according to the ultrasonic principle, the change in temperature will affect the propagation speed of ultrasonic longitudinal waves in the material, thereby affecting the detection accuracy of residual stress. To improve the detection accuracy, temperature compensation and correction should be applied to the detected residual stress values. According to the thermoelastic theory, within a certain temperature range, the travel time of ultrasonic longitudinal waves in the medium has an approximately linear relationship with temperature. Combining the above stress and time difference formula for sound velocity, and based on the experimental data of the influence of temperature on sound velocity in the embodiment, the correction formula for stress due to temperature influence is obtained as follows: σ(T) = C*(T 1 -T 0 ） / K C = (t max -t min ) / (T max -T min ) In the formula: σ(T), the stress correction value caused by temperature change; T 1 is the temperature of the workpiece to be measured; T 0 is the temperature for zero-stress sound time calibration of the zero-stress test block; C is the temperature correction coefficient, which can be obtained through temperature correction experiments; t max and t min are the maximum and minimum sound times during temperature correction experiments; T max and T min are the highest and lowest water temperatures during temperature correction experiments; K is the stress calibration coefficient of the workpiece to be measured, that is, the slope of the test time difference and the stress value; Therefore, the actual stress of the workpiece to be measured should be: σ(actual)=ΚΔt+σ(T) For the experimental example of the present invention, σ(actual)=ΚΔt+0.56(T 1 -T 0 ); As can be seen from the above description of the present invention, the present invention applies ultrasonic stress detection technology to the underwater environment, conducts experiments on the temperature influence factors existing in the underwater environment detection of ultrasonic stress, obtains correction parameters, optimizes the equipment calibration and detection processes, reduces the deviation in underwater structure stress detection, and thus improves the accuracy of underwater environment stress detection.

[0031] Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present invention. Those skilled in the art should understand that various equivalent structural or equivalent process modifications or deformations that can be made without creative efforts based on the technical solutions of the present invention, or direct or indirect applications to other related technical fields, are still within the protection scope of the present invention.

Claims

1. A method for correcting the influencing factor of ultrasonic stress detection in an underwater environment, characterized in that: include: Step 1: Formulate an experimental plan for the test piece and determine the experimental plan for the underwater stress detection device; Step 2: deploying the underwater stress detection device according to the underwater stress detection device experimental plan; Step 3: Performing an underwater stress detection temperature effect sound velocity correction experiment on the test piece by using the underwater stress detection device to obtain ultrasonic sound duration values ​​at different temperatures; Step 4: According to the results of the experiment, the influencing factors of underwater ultrasonic stress detection are analyzed; Step 5: According to the analysis results of the underwater ultrasonic stress detection influencing factors, a correction formula for the underwater ultrasonic stress detection influencing factors is proposed, and the underwater ultrasonic stress value is corrected.

2. The method for correcting the influencing factor of ultrasonic stress detection in an underwater environment according to claim 1, characterized in that: The tested piece in step 3 is a plate sample of structural steel for ships and marine engineering; The formulation of the experimental plan for the test piece in step 1 includes proposing important influencing factors that may affect underwater ultrasonic stress detection and formulating an experimental plan for temperature-induced sound velocity correction of underwater stress detection, wherein the important influencing factor is temperature.

3. The method for correcting the influencing factor of ultrasonic stress detection in an underwater environment according to claim 1, characterized in that: The underwater stress detection device in step 2 includes an ultrasonic residual stress detection host, a stress detection probe configured to match the ultrasonic residual stress detection host, and a signal transmission cable configured to match the ultrasonic residual stress detection host.

4. The ultrasonic stress detection influencing factor correction method according to claim 3 is characterized in that: The ultrasonic residual stress detection host includes a host housing, a display screen, a power supply and a probe interface, an operating system and usage software. The display screen is used to perform detection operations and display the ultrasonic signal amplitude value, ultrasonic wave propagation sound time and the stress value of the detected workpiece.

5. The method for correcting the influencing factor of ultrasonic stress detection in an underwater environment according to claim 3, characterized in that: The stress detection probe comprises a transmitting transducer, a receiving transducer arranged in coordination with the transmitting transducer, and an acoustic wedge block arranged between the transmitting transducer and the receiving transducer.

6. The method for correcting the influencing factor of ultrasonic stress detection in an underwater environment according to claim 3, characterized in that: The ultrasonic residual stress detection host, stress detection probe and signal transmission cable are models produced by domestic manufacturers.

7. The method for correcting the influencing factor of ultrasonic stress detection in an underwater environment according to claim 1, characterized in that: The temperature in step 3 ranges from 0°C to 50°C; The number of different temperature values ​​selected in step 3 is at least 5 and the difference between the highest and lowest temperatures is at least 15°C; The underwater stress detection temperature effect sound velocity correction experiment in step 3 includes: S1. Specify the experimental scenario, which should include the experimental site, environmental water depth, and environmental temperature. The tested piece is placed in different temperature environments at the same water depth, and the ultrasonic residual stress detection host is used to generate an excitation electrical signal. S2, the electrical signal is transmitted through the signal transmission cable to the transmitting transducer of the stress detection probe, the transmitting transducer excites the ultrasonic critical refracted longitudinal wave, the critical refracted longitudinal wave passes through the test piece and is received by the receiving transducer, and the ultrasonic critical refracted longitudinal wave signal is converted into an excitation electrical signal again; S3. The signal transmission cable is transmitted back to the ultrasonic residual stress detection host. When the ultrasonic residual stress detection host obtains the ultrasonic sound under the same water depth and different temperature environment, since the propagation distance of the ultrasonic wave in the test piece remains unchanged, the change of the ultrasonic wave velocity can be reflected by the change of the sound time.

8. The method for correcting the influencing factor of ultrasonic stress detection in an underwater environment according to claim 1, characterized in that: The experimental result in step 4 is the experimental data obtained from the underwater stress detection temperature effect sound velocity correction experiment; The underwater ultrasonic stress detection influencing factor analysis in step 4 is to analyze the change of the ultrasonic sound duration under the different temperature environments.

9. The method for correcting the influencing factor of ultrasonic stress detection in an underwater environment according to claim 1, characterized in that: In the step 5, the underwater ultrasonic stress detection influencing factor is corrected under different temperature environments. According to the experimental data results, a correction formula for the underwater ultrasonic stress detection influencing factor is proposed, and the underwater ultrasonic stress value is corrected.

10. The method for correcting the influencing factor of ultrasonic stress detection in an underwater environment according to claim 9, characterized in that: The derivation process of the correction formula for the underwater ultrasonic stress detection influencing factor is as follows: According to the ultrasonic testing principle, when ultrasonic waves are incident on the surface of the material being tested at the first critical angle, a critical refracted longitudinal wave can be generated inside the material being tested according to Snell's law. According to the principle of acoustic elasticity, the residual stress in the material will affect the propagation speed of ultrasound. When the direction of the residual stress is consistent with the propagation direction of ultrasound, the tensile stress will slow down the propagation speed of ultrasound or the propagation time. t Extension, compression stress makes the ultrasonic wave propagation speed faster or the propagation time t shorter. Therefore, under the condition that the sound path distance remains unchanged, if zero stress is measured σ 0 corresponds to the ultrasonic propagation time t 0 and the ultrasonic propagation time corresponding to the workpiece being inspected t , the residual stress value in the inspected workpiece can be calculated, that is: σ-σ 0 =K(t- t 0 ) or ∆σ=ΚΔt Where: ∆σ—— The change in residual stress (stress difference), ∆σ=σ-σ 0 Δt—— The change in ultrasonic propagation time (acoustic time difference), Δt= (t- t 0 ) K—— The stress coefficient, which is related to the material being tested and the probe spacing, can be obtained through tensile test calibration. According to the thermoelastic theory, within a certain temperature range, the propagation speed of ultrasonic longitudinal waves in the medium (acoustic time) is approximately linearly related to the temperature. From the stress formula above, it can be seen that the stress is also linearly related to the acoustic time. Therefore, the stress correction formula generated by the temperature difference is as follows: σ(T)=C*(T 1 -T 0 ） / K C=(t max -t min ) / (T max -T min ) Where: σ(T), stress correction value caused by temperature change; T1 is the temperature of the workpiece being measured; T0 is the temperature at which the zero stress test block is calibrated for zero stress sound; C is the temperature correction coefficient, which can be obtained through temperature correction experiments; t max and t min The maximum and minimum sound times during the temperature correction experiment; T max and T min The highest and lowest water temperatures during the temperature correction experiment; K is the stress calibration coefficient of the workpiece under test, that is, the slope of the test sound time difference and the stress value; Therefore, the actual stress of the workpiece being measured should be: σ(real)=ΚΔt+σ(T) .

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