Non-contact x-ray diffraction-based steel pipe circumferential hardness uniformity detection method and seamless steel pipe

Abstract

The application discloses a seamless steel pipe and a steel pipe circumferential hardness uniformity detection method based on non-contact X-ray diffraction, and relates to the technical field of seamless steel pipe detection. The method comprises the following steps: synchronously irradiating the circumferential equidivided positions of the steel pipe with an X-ray beam at a fixed incident angle, and simultaneously collecting the surface layer diffraction spectrum of each circumferential position; combining a dislocation density model to convert the diffraction peak shape deformation parameters into micro residual stress gradient values; dynamically generating a hardness distribution function according to the obtained residual stress gradient values of each circumferential position, and calculating the relative deviation rate of the hardness values of adjacent regions; based on the circumferential full-cycle hardness distribution function, an isocurve topological map is drawn, when the relative deviation rate of the hardness of adjacent regions exceeds a set threshold value, the circumferential hardness non-uniform section is marked, and a hardness uniformity evaluation report and a defect position coordinate are output. The application realizes non-contact rapid measurement of the circumferential hardness of the steel pipe, greatly improves the efficiency and precision, and automatically marks the defect region.

Description

Technical Field

[0001] This invention relates to the field of steel pipe quality inspection technology, and in particular to a method for detecting the circumferential hardness uniformity of steel pipes based on non-contact X-ray diffraction and a seamless steel pipe. Background Technology

[0002] As a core component in energy transmission, high-voltage equipment, and precision machinery, the circumferential hardness uniformity of steel pipes is a key indicator for evaluating material performance consistency and product reliability. Uneven circumferential hardness distribution can easily lead to localized stress concentration, premature failure, or fatigue damage; therefore, efficient and comprehensive testing is essential.

[0003] Currently, the industry primarily relies on contact hardness testers, such as Brinell or Rockwell hardness testers, to test the circumferential hardness of steel pipes. This method requires the probe to be stably pressed against specific points on the pipe wall for measurement. The operation process necessitates manual point-by-point positioning and pressure application or reliance on complex automated equipment to move the probe. This method is significantly time-consuming for single-point measurements, resulting in low efficiency for multi-point circumferential testing of a single steel pipe, making it difficult to meet the needs of large-scale production or rapid online testing. More importantly, due to limitations in probe contact methods and the curvature of the steel pipe, existing methods struggle to achieve a high-density, continuous, and comprehensive deployment of test points along the circumference of the steel pipe. Blind spots or sparsely populated areas often exist, making it difficult for the obtained data to fully and accurately represent the uniformity of hardness across the entire circumference. Although attempts have been made to improve efficiency through multi-probe arrays, the high cost and the unresolved issue of full circumferential coverage remain. The core bottleneck lies in the requirements of physical contact and stable loading for contact measurements, fundamentally limiting the improvement of testing speed and coverage.

[0004] Therefore, developing a new non-contact, highly efficient method that can achieve seamless and comprehensive testing of the circumferential hardness of steel pipes has become an urgent technical challenge. Summary of the Invention

[0005] In view of this, the present invention proposes a method for detecting the circumferential hardness uniformity of steel pipes based on non-contact X-ray diffraction and a seamless steel pipe, so as to solve the problems of low efficiency and incomplete coverage in the existing technology for detecting the circumferential hardness of steel pipes.

[0006] The specific technical solution of this invention is as follows:

[0007] A method for detecting the circumferential hardness uniformity of steel pipes based on non-contact X-ray diffraction includes: Step 1: Multiple independently rotatable X-ray sources and detector arrays are arranged in a ring around the periphery of the steel pipe so that the X-ray beam synchronously irradiates the equally divided positions around the periphery of the steel pipe at a fixed incident angle, and the surface diffraction patterns of each position are collected simultaneously without contacting the pipe body. Step 2: Analyze the full width at half maximum (FWHM) and peak position offset of diffraction peaks in diffraction patterns at each position in real time. Quantify the degree of crystal distortion by calculating the integral width. Combine the dislocation density model to convert the diffraction peak deformation parameters into microscopic residual stress gradient values. Step 3: Establish a nonlinear mapping correlation model between residual stress gradient and microhardness. Based on the residual stress gradient values ​​at each circumferential position obtained in Step 2, dynamically generate the hardness distribution function and calculate the relative deviation rate of hardness values ​​in adjacent regions. Step 4: Draw a contour map based on the circumferential full-cycle hardness distribution function. When the relative hardness deviation rate of adjacent areas exceeds the set threshold, it is marked as a circumferential hardness non-uniform segment. Output a hardness uniformity evaluation report and defect location coordinates.

[0008] Specifically, in step 1, the central axis of the annular mounting bracket coincides with the central axis of the steel pipe, and the number of detection units is dynamically adjusted according to the circumferential detection angle resolution requirements; when the resolution requirement does not exceed 5 degrees, the number of detection units is not less than 72 groups; when the outer diameter of the steel pipe exceeds 500 mm, the number of detection units is increased to ensure detection coverage.

[0009] Specifically, in step 1, the incident angle of the X-ray source is selected according to the type of steel pipe material: for ferritic steel pipes, the incident angle is 20 to 30 degrees; for austenitic steel pipes, the incident angle is 30 to 40 degrees; the incident angle is adjusted by an electric rotary table, and the control accuracy is not less than 0.1 degrees.

[0010] Specifically, before step 1, a standard test block with known hardness is used for calibration. The standard test block includes three hardness levels: low, medium, and high, and the material is the same as that of the steel pipe being tested. After calibration, a verification test block is used to confirm that the deviation does not exceed ±3%; otherwise, the parameters are readjusted.

[0011] Specifically, in step 2, real-time analysis of the diffraction pattern includes: removing background noise and generating a background curve by fitting the peakless region with a polynomial; performing Savitzky-Golay filtering on the background-removed pattern with a filtering window of 5 to 11 points; and fitting at least two characteristic diffraction peaks with a Lorentz function or a Gaussian function and taking the average value as the final characteristic parameter.

[0012] Specifically, in step 2, the dislocation density model adopts the Williamson-Hall model, and the dislocation density is calculated by separating the grain size and the contribution of micro-strain; the micro-residual stress gradient value is obtained by fitting the penetration depth data under different X-ray energies.

[0013] Specifically, in step 3, the nonlinear mapping correlation model is constructed based on the corresponding data of residual stress gradient and microhardness, using multinomial regression, support vector regression or neural network algorithm.

[0014] Specifically, in step 1, if multiple axial sections need to be inspected, after one section is inspected, the load-bearing fixture is controlled to move the steel pipe axially in steps of 10 mm to 100 mm, and steps 1 to 4 are repeated.

[0015] Specifically, in step 3, the hardness distribution function is generated using spline interpolation; the formula for calculating the relative hardness deviation rate between adjacent regions is: Relative deviation rate = |H1 - H2| / [(H1 + H2) / 2] × 100%; Where H1 and H2 are the hardness values ​​of adjacent regions.

[0016] A seamless steel pipe is obtained by processing the aforementioned method for detecting the circumferential hardness uniformity of steel pipes based on non-contact X-ray diffraction.

[0017] The beneficial effects of this invention are as follows: 1. Through the ring synchronous detection design, efficient parallel acquisition of the circumferential hardness distribution of steel pipes is achieved, significantly shortening the single detection cycle; combined with multi-position synchronous diffraction analysis, the cumulative error of traditional point-by-point detection is eliminated, and the integrity and reliability of circumferential hardness distribution data are comprehensively improved.

[0018] 2. Based on real-time analysis of diffraction pattern characteristic parameters, the degree of crystal distortion on the surface of the material is accurately quantified; through the mapping relationship between the dislocation density model and the residual stress gradient, the micromechanical state is characterized non-destructively, providing a theoretical basis for hardness uniformity.

[0019] 3. Establish a nonlinear correlation model between residual stress gradient and microhardness to generate a continuous circumferential hardness distribution function; through hardness deviation analysis of adjacent regions, automatically identify local non-uniform sections to achieve rapid and accurate location of defects.

[0020] 4. Generate contour map based on circumferential hardness distribution function to intuitively present hardness gradient changes; automatically mark abnormal sections with preset thresholds and output quantitative evaluation report containing defect coordinates to improve the objectivity and operability of quality judgment. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic flowchart of the method for detecting the circumferential hardness uniformity of steel pipes based on non-contact X-ray diffraction according to the present invention. Detailed Implementation

[0023] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0024] This invention proposes a method for detecting the circumferential hardness uniformity of steel pipes based on non-contact X-ray diffraction, and a seamless steel pipe thereof. The seamless steel pipe is processed using this method. This method is particularly suitable for high-precision, non-contact online detection of surface hardness uniformity after annealing. This invention achieves simultaneous detection at multiple locations along the circumference of the steel pipe using a ring-shaped array of X-ray sources and detectors. Combined with diffraction pattern analysis and a stress-hardness mapping model, the circumferential hardness distribution is rapidly obtained, significantly improving both detection efficiency and accuracy. Figure 1 As shown, the method of the present invention includes the following steps: Step 1: Multiple independently rotatable X-ray sources and detector arrays are arranged in a ring around the circumference of the steel pipe, so that the X-ray beams synchronously irradiate equally divided positions around the circumference of the steel pipe at a fixed incident angle, and the surface diffraction patterns of each circumferential position are collected simultaneously without contacting the pipe body.

[0025] Before testing, the testing system must first be debugged according to the specifications of the steel pipe being tested. These specifications include the pipe's outer diameter, wall thickness, material grade, and processing technology. First, the steel pipe is fixed onto a rotatable support fixture, ensuring that the pipe's central axis is perfectly aligned with the fixture's rotation axis. The fixture's rotation accuracy is controlled within ±0.5 degrees to prevent radial runout during rotation, which could affect the accuracy of the test results. Next, an annular mounting bracket is installed around the steel pipe, with its central axis aligned with the pipe's central axis. The diameter of the bracket is adjusted according to the pipe's outer diameter to ensure the distance between the X-ray source and the pipe's outer surface is within a preset range. Multiple detection units are arranged at equal intervals along the circumference of the ring-shaped mounting bracket. Each detection unit includes an independently rotatable X-ray source and a corresponding X-ray detector. The number of detection units is determined according to the circumferential detection resolution requirements of the steel pipe. When the required circumferential detection angle resolution is no more than 5 degrees, the number of detection units should be no less than 72. When the outer diameter of the steel pipe exceeds 500 mm, the number of detection units can be appropriately increased to ensure that the detection coverage meets the requirements. The initial emission angle of the X-ray source of each detection unit can be adjusted by an electric rotary table. The angle control accuracy of the electric rotary table is no less than 0.1 degrees. Adjusting the emission angle of the X-ray source ensures that the center line of the X-ray beam irradiates the surface detection point of the steel pipe at a fixed incident angle. The incident angle ranges from 15 degrees to 45 degrees. The specific value is selected according to the crystal structure of the steel pipe being tested. For ferritic steel pipes, the incident angle is selected between 20 degrees and 30 degrees, and for austenitic steel pipes, the incident angle is selected between 30 degrees and 40 degrees. A beam-limiting aperture is installed at the exit port of each X-ray source. The size of the exit window of the beam-limiting aperture is adjusted according to the size requirements of the detection point to ensure that the diameter of the X-ray beam irradiating the steel tube surface is controlled between 1 mm and 5 mm. This avoids the beam being too large and covering multiple different tissue areas, which would affect the representativeness of the detection results. The position and angle of the X-ray detector are adjusted so that the receiving surface of the detector is directly facing the diffraction direction of the X-ray beam on the steel tube surface, ensuring that the reception efficiency of the diffraction signal is maximized. The energy resolution of each detector is not less than 100 eV, and the acquisition frame rate is not less than 10 frames per second to meet the requirements of rapid detection.

[0026] After the testing system is deployed, it needs to be calibrated to ensure the accuracy of the test results. First, standard test blocks of the same material and known hardness as the steel pipe being tested are used for calibration. The hardness values ​​of the standard test blocks cover the expected hardness range of the steel pipe being tested, and include at least three different hardness levels: low, medium, and high. The standard test blocks are fixed at the installation position of the steel pipe, the X-ray source is activated, and diffraction patterns of test blocks with different hardness are acquired. Characteristic parameters such as the full width at half maximum (FWHM) and peak position shift corresponding to different hardnesses are recorded to establish the correspondence between diffraction characteristic parameters and residual stress and microhardness. For each standard test block, multiple acquisitions are required at multiple different locations, and the average value of the characteristic parameters is taken as the standard value corresponding to that hardness to reduce the influence of random errors. After calibration, a verification test block with known hardness is used for verification. If the deviation between the test result and the actual hardness value does not exceed ±3%, the system calibration is considered qualified. If the deviation exceeds this range, the incident angle of the X-ray source, the position of the detector, and other parameters need to be readjusted, and calibration is performed again until the verification result meets the requirements.

[0027] During formal testing, all X-ray sources are first activated, irradiating the steel pipe circumferentially at pre-set fixed incident angles to the equally spaced detection points. The operating voltage of the X-ray sources is set between 30kV and 50kV, and the operating current between 10mA and 50mA. Specific parameters are adjusted according to the material and wall thickness of the steel pipe. For thicker steel pipes, the operating voltage and current are appropriately increased to ensure the intensity of the diffraction signal meets the testing requirements. The irradiation time of each X-ray source is kept consistent, set between 0.1 seconds and 1 second, and adjusted according to the intensity of the diffraction signal to ensure the signal-to-noise ratio of the diffraction pattern is not less than 10:1. Simultaneously with the X-ray irradiation, the corresponding detectors synchronously acquire the surface diffraction patterns at each circumferential position. The acquired diffraction pattern data is transmitted in real time to the data processing unit for subsequent analysis. If it is necessary to test multiple axial sections of the steel pipe, after completing the test of one section, control the bearing fixture to move the steel pipe axially by a preset distance, repeat the above testing steps, and complete the circumferential hardness test of multiple axial sections. The step length of axial movement is determined according to the axial detection resolution requirements, and the range is between 10mm and 100mm.

[0028] Step 2: Analyze the full width at half maximum (FWHM) and peak position offset of diffraction peaks in the diffraction patterns at each position in real time. Quantify the degree of crystal distortion by calculating the integral width. Combine the dislocation density model to convert the diffraction peak deformation parameters into microscopic residual stress gradient values.

[0029] After receiving the diffraction patterns from various locations, the data processing unit first performs preprocessing operations on the diffraction patterns. These preprocessing operations include background noise subtraction, smoothing filtering, and peak position fitting. First, background noise is subtracted from the diffraction pattern using a polynomial fitting method. The peakless regions on either side of the diffraction peaks are selected as the fitting interval, and a 3rd or 5th order polynomial is used to obtain the background noise curve. The original diffraction pattern is then subtracted from the background noise curve to obtain the background-subtracted diffraction pattern. Next, the background-subtracted diffraction pattern undergoes smoothing filtering using the Savitzky-Golay filtering algorithm. The filtering window size is set between 5 and 11 points to remove high-frequency noise interference while preserving the diffraction peak characteristics. After smoothing, the diffraction peaks are fitted using a Lorentz function or a Gaussian function to obtain the precise peak position, full width at half maximum (FWHM), and integral intensity of the diffraction peaks. For each diffraction pattern, at least two characteristic diffraction peaks are selected for analysis, and the average of the calculated results from multiple diffraction peaks is taken as the final characteristic parameter for that location, improving the reliability of the detection results.

[0030] After obtaining the characteristic parameters of the diffraction peaks at each position, the full width at half maximum (FWHM) and peak position shift of the diffraction peaks are first calculated. The peak position shift refers to the difference between the measured diffraction peak position and the standard diffraction peak position under stress-free conditions. The standard diffraction peak position under stress-free conditions is pre-determined using a stress-free standard specimen of the same material. Then, the degree of crystal distortion is quantified by calculating the integral width of the diffraction peak. The integral width is the width obtained by dividing the integral intensity of the diffraction peak by the peak intensity. Compared to FWHM, the integral width more comprehensively reflects the degree of deformation of the diffraction peak. The integral width is then substituted into the dislocation density model to calculate the dislocation density at that position. The Williamson-Hall dislocation density model is used, which considers the combined influence of grain size and microstrain on diffraction peak broadening. By linearly fitting the diffraction peak broadening data of multiple different crystal planes, the contributions of grain size and microstrain are separated, and the dislocation density is then calculated. The microscopic residual stress gradient at this location was then calculated based on the microscopic strain value. The residual stress was calculated using the sin²ψ method, and the residual stress value was obtained by calculating the diffraction peak position shift at different tilt angles. The residual stress gradient refers to the rate of change of residual stress along the depth direction of the steel pipe surface. It was calculated by collecting diffraction signals at different penetration depths. The X-ray penetration depth was controlled by adjusting the X-ray energy. For iron-based materials, the penetration depth was approximately 5 μm when the X-ray energy was 8 kV and approximately 20 μm when the energy was 15 kV. By collecting diffraction signals at multiple different energies, the residual stress values ​​at different depths were obtained, and then the residual stress gradient value was obtained by fitting.

[0031] Step 3: Establish a nonlinear mapping correlation model between residual stress gradient and microhardness. Based on the residual stress gradient values ​​at each circumferential position obtained in Step 2, dynamically generate the hardness distribution function and calculate the relative deviation rate of hardness values ​​in adjacent regions.

[0032] Next, a nonlinear mapping correlation model between residual stress gradient and microhardness is established. This model is constructed using preliminary calibration test data. Specifically, a large amount of measured microhardness data corresponding to different residual stress gradients is obtained. The residual stress gradient is determined by X-ray diffraction, and the microhardness is measured using a Vickers hardness tester. The data sample size is no less than 1000 sets, covering all possible residual stress and hardness ranges of the tested material. The residual stress gradient is used as the input variable, and the corresponding microhardness as the output variable. Algorithms such as multinomial regression, support vector regression, or neural networks are used for fitting to obtain the nonlinear mapping correlation model. For steel pipes of different materials, corresponding mapping models need to be constructed separately to ensure the accuracy of the model. After the model is constructed, it is validated using a validation dataset. If the model's prediction error does not exceed ±3%, it can be used for hardness calculation in actual testing. The residual stress gradient values ​​at each circumferential position obtained in step 2 are input into this mapping correlation model to calculate the microhardness value at each position. Then, based on the hardness values ​​at all circumferential positions, a hardness distribution function for the entire circumferential period is generated using spline interpolation. This hardness distribution function can be represented as a continuous function of hardness values ​​varying with the circumferential angle. Next, the relative deviation rate of hardness values ​​between adjacent circumferential regions is calculated. The formula for calculating the relative deviation rate is: .

[0033] Step 4: Draw a contour map based on the circumferential full-cycle hardness distribution function. When the relative hardness deviation rate of adjacent areas exceeds the set threshold, it is marked as a circumferential hardness non-uniform segment. Output a hardness uniformity evaluation report and defect location coordinates.

[0034] After obtaining the circumferential hardness distribution function and the relative hardness deviation rate of each adjacent region, a hardness contour map is first drawn based on the circumferential full-cycle hardness distribution function. The interval of the contour lines is set according to the hardness testing accuracy requirements, ranging from 5HV10 to 20HV10. The contour map provides a clear view of the circumferential hardness distribution of the steel pipe, clearly distinguishing between areas with higher and lower hardness. Next, a threshold for the relative hardness deviation rate is pre-set. The threshold value is determined based on the application scenario and quality requirements of the steel pipe. For ordinary structural steel pipes, the threshold is set between 10% and 15%; for high-pressure oil and gas transmission steel pipes, the threshold is set between 5% and 8%; and for high-end aerospace steel pipes, the threshold is set between 3% and 5%. The calculated relative hardness deviation rate of each adjacent region is compared with the set threshold. When the relative hardness deviation rate of an adjacent region exceeds the set threshold, that region is marked as a circumferential hardness non-uniform segment, and the corresponding circumferential angle range is recorded as the defect location coordinates. Finally, a hardness uniformity evaluation report is output. The report includes basic information about the tested steel pipe, testing time, testing environment parameters, hardness values ​​at each circumferential position, circumferential hardness distribution curve, contour map, location and deviation rate of non-uniform sections, and comprehensive evaluation conclusions on hardness uniformity. If abnormalities such as low diffraction signal intensity or insufficient signal-to-noise ratio occur during the testing process, this should be noted in the report, and a retest should be requested.

[0035] This invention is not only applicable to the circumferential hardness uniformity testing of steel pipes, but can also be extended to the hardness uniformity testing of other cylindrical metal components, such as round steel, aluminum pipes, and copper pipes. It only requires adjusting the corresponding mapping model and testing parameters according to different materials.

[0036] The beneficial effects of this invention are as follows: 1. By using non-contact synchronous testing of multiple circumferential positions on steel pipes, the efficiency bottleneck of traditional single-point testing is broken through, while avoiding measurement errors caused by contact, thus fully ensuring the accuracy of the test results.

[0037] 2. Based on real-time analysis of diffraction pattern characteristic parameters, the degree of material crystal distortion can be accurately characterized, and non-destructive quantitative assessment of microscopic residual stress gradient can be achieved, providing a reliable basis for hardness analysis.

[0038] 3. Establish a nonlinear correlation model between residual stress and hardness, dynamically construct a continuous distribution function of circumferential hardness, automatically identify the degree of hardness difference between adjacent regions, and accurately locate non-uniform defect sections.

[0039] 4. The hardness distribution topology map visually presents the circumferential hardness variation trend, automatically marks abnormal areas and generates a comprehensive evaluation report including the location of defects, greatly improving the efficiency and reliability of quality judgment.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for detecting the circumferential hardness uniformity of steel pipes based on non-contact X-ray diffraction, characterized in that, include: Step 1: Multiple independently rotatable X-ray sources and detector arrays are arranged in a ring around the periphery of the steel pipe so that the X-ray beam synchronously irradiates the equally divided positions around the periphery of the steel pipe at a fixed incident angle, and the surface diffraction patterns of each position are collected simultaneously without contacting the pipe body. Step 2: Analyze the full width at half maximum (FWHM) and peak position offset of diffraction peaks in diffraction patterns at each position in real time. Quantify the degree of crystal distortion by calculating the integral width. Combine the dislocation density model to convert the diffraction peak deformation parameters into microscopic residual stress gradient values. Step 3: Establish a nonlinear mapping correlation model between residual stress gradient and microhardness. Based on the residual stress gradient values ​​at each circumferential position obtained in Step 2, dynamically generate the hardness distribution function and calculate the relative deviation rate of hardness values ​​in adjacent regions. Step 4: Draw a contour map based on the circumferential full-cycle hardness distribution function. When the relative hardness deviation rate of adjacent areas exceeds the set threshold, it is marked as a circumferential hardness non-uniform segment. Output a hardness uniformity evaluation report and defect location coordinates.

2. The method for detecting the circumferential hardness uniformity of steel pipes as described in claim 1, characterized in that, In step 1, the central axis of the annular mounting bracket coincides with the central axis of the steel pipe, and the number of detection units is dynamically adjusted according to the circumferential detection angle resolution requirements; when the resolution requirement does not exceed 5 degrees, the number of detection units is not less than 72 sets; when the outer diameter of the steel pipe exceeds 500 mm, the number of detection units is increased to ensure detection coverage.

3. The method for detecting the circumferential hardness uniformity of steel pipes as described in claim 1, characterized in that, In step 1, the incident angle of the X-ray source is selected according to the type of steel pipe material: for ferritic steel pipes, the incident angle is 20 to 30 degrees; for austenitic steel pipes, the incident angle is 30 to 40 degrees; the incident angle is adjusted by an electric rotary table, and the control accuracy is not less than 0.1 degrees.

4. The method for detecting the circumferential hardness uniformity of steel pipes as described in claim 1, characterized in that, Before step 1, calibration is performed using a standard test block with known hardness. The standard test block includes three hardness levels: low, medium, and high, and the material is the same as that of the steel pipe being tested. After calibration, a verification test block is used to confirm that the deviation does not exceed ±3%; otherwise, the parameters are readjusted.

5. The method for detecting the circumferential hardness uniformity of steel pipes as described in claim 1, characterized in that, In step 2, the real-time analysis of the diffraction pattern includes: removing background noise, generating a background curve by fitting the peakless region with a polynomial; performing Savitzky-Golay filtering on the background-removed pattern with a filtering window of 5 to 11 points; fitting at least two characteristic diffraction peaks with a Lorentz function or a Gaussian function, and taking the average value as the final characteristic parameter.

6. The method for detecting the circumferential hardness uniformity of steel pipes as described in claim 1, characterized in that, In step 2, the dislocation density model adopts the Williamson-Hall model, and the dislocation density is calculated by separating the grain size and the contribution of micro-strain; the micro-residual stress gradient value is obtained by fitting the penetration depth data under different X-ray energies.

7. The method for detecting the circumferential hardness uniformity of steel pipes as described in claim 1, characterized in that, In step 3, the nonlinear mapping correlation model is constructed based on the corresponding data of residual stress gradient and microhardness, and adopts multinomial regression, support vector regression or neural network algorithm.

8. The method for detecting the circumferential hardness uniformity of steel pipes as described in claim 1, characterized in that, In step 1, if multiple axial sections need to be inspected, after one section is inspected, the load-bearing fixture is controlled to move the steel pipe axially in steps of 10 mm to 100 mm, and steps 1 to 4 are repeated.

9. The method for detecting the circumferential hardness uniformity of steel pipes as described in claim 1, characterized in that, In step 3, the hardness distribution function is generated using spline interpolation; the formula for calculating the relative hardness deviation rate between adjacent regions is: Relative deviation rate = |H1 - H2| / [(H1 + H2) / 2] × 100%; H1 and H2 are the hardness values ​​of adjacent regions.

10. A seamless steel pipe, characterized in that, The seamless steel pipe is obtained by processing the steel pipe circumferential hardness uniformity detection method based on non-contact X-ray diffraction as described in any one of claims 1 to 9.

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