A method for measuring the pore height of submerged arc welded steel pipe

Abstract

The present invention provides a method for measuring the height of pores in a submerged arc welded steel pipe, including preparation before measurement; adjusting the measurement software; using an X-ray machine to detect the weld of the steel pipe and the groove comparison test block, and capturing and acquiring digital images with a flat-panel detector; calibrating the geometric dimensions of the collected images; using an X-ray machine to detect the weld of the steel pipe in real time, and using the measurement software to record the digital imaging of the weld of the steel pipe in real time; using software tools to measure the grayscale uniformity area of ​​the weld of the submerged arc welded steel pipe, the grayscale value of each groove of the groove comparison test block; measuring the maximum grayscale value of the pore to determine whether the pore is a deep hole; and calculating the height of the pore. The present invention has a high measurement accuracy and provides a basis for evaluating whether the submerged arc welding pore is a deep hole. In production and use, it can reduce the cost of pore rework and the cost of cutting off the end of the steel pipe, assist production units in improving welding quality, improve the depth discrimination of other defects, and ensure product quality. It is suitable for popularization and use.

Description

Technical Field

[0001] The invention relates to the field of submerged arc welded steel pipe detection, in particular to a method for measuring pore height of submerged arc welded steel pipe. Background Art

[0002] Since the pores in submerged arc welded steel pipes are directional, when the size of the pores perpendicular to the weld direction is deep, it may cause the possibility of leakage in the submerged arc welded pipe. Therefore, the detection and judgment of deep hole defects is very important. At present, the commonly used detection method for submerged arc welded steel pipe pores is X-ray detection. The pores displayed by traditional film photography technology and digital radiography technology are two-dimensional images, which can only measure their size on the plane, and cannot measure the height perpendicular to the weld direction. The judgment of deep holes is to compare the blackness displayed on the film with the surrounding area. The blackness meter is limited by the size of the measuring hole and cannot accurately measure the subtle blackness changes. The judgment result is affected by personal subjectivity. For the height measurement of the pores of submerged arc welded steel pipes perpendicular to the weld direction, bidirectional inclined ray transillumination is used. The irradiation angle is not easy to control, the geometric unsharpness is large, the measurement data is not accurate enough, and it is not suitable for conventional detection methods. For this reason, we propose a method for measuring the height of pores in submerged arc welded steel pipes to solve the above problems.

[0003] Chinese patent document CN114137009A records a method for judging whether a weld of a spiral submerged arc welded steel pipe has porosity defects. It is concluded that when the total length of MnS inclusions in the longitudinal section of the core of the rolled material is less than 130 μm, the rolled material is not likely to have porosity defects after spiral submerged arc welding. A method for judging whether the total length of MnS inclusions in the longitudinal section of the core of the rolled material is less than 130 μm by using the roughness of the acid-etched surface of a metallographic sample is provided. When the roughness of the metallographic sample to be tested is less than that of the standard metallographic sample, it is obtained that the total length of manganese sulfide inclusions in the longitudinal section of the core of the rolled material to be tested of the metallographic sample to be tested is less than 130 μm, and it is further concluded that the weld of the rolled material to be tested does not have porosity defects. The present invention does not require X-ray flaw detection of the weld after the rolled material is welded to determine whether porosity defects are likely to occur. The method is simple, fast, low-cost, and highly accurate, and is suitable for enterprises with simple production equipment such as steelmaking and continuous casting. However, this method is complicated to operate and requires more auxiliary materials. It is not suitable for large-scale submerged arc welding inspection lines. It is not suitable for submerged arc welding steel pipe porosity inspection on large-scale assembly lines. It has defects in use and needs to be improved. Summary of the invention

[0004] The present invention provides a method for measuring the height of pores in submerged arc welded steel pipes, which solves the problem that the conventional submerged arc welded steel pipe pore detection is a two-dimensional image, which can only measure the size on the plane but cannot measure the height perpendicular to the weld direction; the deep hole is determined by comparing the blackness of the pore displayed on the film with the surrounding area, the blackness meter is limited by the size of the measuring hole, cannot accurately measure subtle blackness changes, and the determination result is affected by personal subjectivity.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for measuring the pore height of a submerged arc welded steel pipe, comprising the following steps:

[0006] S1. Preparation before measurement: determine the detection system, steel pipe specifications, and transillumination parameters;

[0007] S2. Adjust the measurement software: set the number of flat panel detector frame stacking times, frame rate, offset correction, gain correction, and file storage format;

[0008] S3. Static testing, obtaining images of steel pipe welds and groove comparison test blocks: Use an X-ray machine to test the steel pipe welds and groove comparison test blocks, and the flat panel detector captures and obtains digital images;

[0009] S4, calibrating the geometric size of the image collected in S3: converting the image pixels into actual geometric size;

[0010] S5. Use an X-ray machine to perform real-time inspection on the weld of the steel pipe, and use measurement software to record the digital imaging of the weld of the steel pipe in real time;

[0011] S6. Measure grayscale values: Use software tools to change the grayscale range of the image display to achieve the best effect of human eye recognition, and measure the grayscale uniform area of ​​the weld of the submerged arc welded steel pipe, the grayscale uniform area of ​​the parent material, and the grayscale values ​​of each groove of the groove comparison test block;

[0012] S7. Measure the maximum gray value of the pores to determine whether the pores are deep holes; and calculate the height of the pores.

[0013] In a preferred embodiment, a plurality of grooves are provided on the groove comparison test block in S3, and the depth of the grooves increases sequentially from one end to the other end of the groove comparison test block.

[0014] In the preferred scheme, in step S3, static detection is performed to obtain images of the steel pipe weld and the groove comparison test block, the groove comparison test block is located on one side of the steel pipe weld, the steel pipe weld detection position is adjusted to the center area of ​​the detector, and the X-ray passes through the submerged arc welded steel pipe to form a real-time image on the flat-panel detector, and the digital image is obtained using the static image capture function of the software.

[0015] In a preferred solution, the method for calibrating the geometric dimensions in S4 is: collecting the groove comparison test block image, measuring the number of pixels of the test block image size by software, calculating the geometric factor, and calibrating its geometric dimensions.

[0016] In the preferred scheme, the maximum grayscale value of the pore is measured in S7 to determine whether the pore is a deep hole: the maximum grayscale value of the pore is measured by a software tool, and the grayscale value is substituted into the formula to calculate the height value. When the grayscale value is greater than or equal to the grayscale value of the maximum depth groove of the groove comparison test block, it can be determined as a deep hole.

[0017] In a preferred embodiment, the maximum groove depth is the allowable pore height.

[0018] In the preferred solution, the method for determining the pore height in S7 is:

[0019] A1: Calculate the grayscale of pore defect contrast: G 气 -G 母 =-0.434uγ△T / (1+n) Formula (1);

[0020] A2: Calculate the grayscale contrast of the groove test block: G t1 -G t2 =-0.434uγ(T1-T2) / (1+n) formula (2);

[0021] A3: Calculate the pore height H: The pore height H is the ratio of the pore defect contrast grayscale to the groove test block contrast grayscale. Divide formula (1) by formula (2) and arrange them to get:

[0022] H=(G 气 -G 母 )·(T1-T2) / (G t1 -G t2 ) formula (3);

[0023] In the formula, the height is H, the thickness difference with the parent material is △T, the average grayscale at the parent material is Gparent, the maximum grayscale at the pore is Ggas, the grayscales of any two grooves on the groove specimen are Gt1 and Gt2, the depths are T1 and T2, and it is assumed that u, γ, and n in the transillumination area are the same.

[0024] The beneficial effects of the present invention are as follows: the shape and quantity of the pores of the submerged arc welded steel pipe can be intuitively obtained through digital images, and the plane dimensions can be accurately measured by calibrating the geometric dimensions through software. By using a groove comparison test block, the corresponding relationship between the grayscale and the defect height can be measured by software to determine whether the pore is a deep hole.

[0025] The present invention adopts the technical solution of X-ray digital imaging detection method plus groove comparison test block, which can accurately measure the depth of pores. Traditional technology uses X-ray irradiation, and the size of smaller pores on the film may be 1-2mm, and the size of the pores cannot be judged by the naked eye of the staff. The digital imaging collected by the measurement software used in the present invention can scale the collected pore images, further improving the accuracy of the pore height measurement of submerged arc welded steel pipes. The traditional technology of X-ray irradiation is used to image the pores on the black meter. The black meter is limited by the size of the measuring hole and cannot accurately measure the subtle blackness changes. The judgment result is affected by personal subjectivity; at the same time, the judgment of the black meter requires a deeper non-destructive testing qualification. The staff with a higher non-destructive testing grade certificate need a long time of practical operation and learning and training, while the present invention is simple to operate and can intuitively determine whether the pore is a deep hole by the data size, saving a lot of artificial training costs and reducing the cost of detecting and measuring submerged arc welded steel pipes.

[0026] The present invention can compensate for the inconsistency of the human eye's subjective belief that the blackness is greater than that of the parent material, accurately calculate the height of the pores in the submerged arc welded steel pipe, determine whether it is a deep hole, and determine its severity. To compensate for the limitations of the size of planar defects in X-ray detection, accurately determine whether the pores in the submerged arc welded steel pipe are deep holes, and provide a reliable basis for X-ray detection personnel to make inconsistent judgments. The present invention has a high measurement accuracy and provides a basis for assessing whether the submerged arc welding pores are deep holes. In production and use, it can reduce the cost of pore rework and steel pipe end cutting, assist production units to improve welding quality, verify whether the performance of the digital imaging system and the adopted X-ray detection process parameters meet the standard requirements, improve the depth discrimination of other defects, and ensure product quality. It is suitable for popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments;

[0028] Figure 1 is a front view of a groove comparison test block of the present invention;

[0029] Figure 2 is a top view of a groove comparison test block of the present invention;

[0030] Figure 3 This is a schematic diagram of the grayscale measurement of pores by X-ray digital imaging of the present invention;

[0031] Figure 4 It is a digital image of the steel pipe weld and groove comparison test block captured by the flat panel detector of the present invention; DETAILED DESCRIPTION

[0032] Embodiment 1:

[0033] like Figure 1-4In the test, the X-ray digital imaging detection method plus the groove comparison test block technical solution was adopted. The steps are as follows: preparation before measurement: determine the detection system, determine the steel pipe specifications, determine the penetration parameters, adjust the measurement software: set the number of flat panel detector frame superpositions, frame rate, offset correction, gain correction, and file storage format for the flat panel; before X-ray detection of submerged arc welded steel pipes, set the penetration parameters according to the process card, use the wall thickness micrometer to measure the actual wall thickness and weld excess height of the steel pipe end, and place the self-made groove comparison test block on the 2-5mm parent material on one side of the weld to be inspected. The maximum groove depth is the height of the pores allowed.

[0034] Static detection, obtain the steel pipe weld and groove comparison test block image: use X-ray machine to detect steel pipe weld and groove comparison test block, flat panel detector captures digital image, static detection, obtain steel pipe weld and groove comparison test block image, groove comparison test block is located on one side of the steel pipe weld, steel pipe weld detection part is adjusted to the center area of ​​the detector, X-ray passes through the submerged arc welded steel pipe and forms a real-time image on the flat panel detector, and the software static image capture function is used to obtain the digital image. Calibrate the geometric size of the collected image: convert the image pixels into actual geometric size, collect the groove comparison test block image, and calculate the geometric factor by measuring the number of pixels obtained by the test block image size by the software.

[0035] Use an X-ray machine to detect the steel pipe weld in real time, and use measurement software to record the digital image of the steel pipe weld in real time. Use software tools to change the grayscale range of the image display to achieve the best effect of human eye recognition, and measure the submerged arc weld steel pipe weld, the grayscale uniform area of ​​the parent material, and the grayscale value of each groove of the groove comparison test block.

[0036] Measure the maximum gray value of the pores to determine whether the pores are deep holes; and calculate the height of the pores. Use X-ray digital imaging to detect the welds of submerged arc welded steel pipes, measure the maximum gray value of the pores through software tools, substitute the gray value into the formula to calculate the height value, and when the gray value is greater than or equal to the gray value of the maximum groove, it can be determined as a deep hole.

[0037] According to the film contrast formula, let the pore height be H, the thickness difference with the base material be △T, and the average grayscale of the base material be G. 母 , the maximum gray level at the pore is G 气 , the gray scale of any two grooves on the groove test block is G t1 and G t2 , the depths are T1 and T2, and u, γ, and n are assumed to be the same in the transillumination area.

[0038] By G 气 -G 母 =-0.434uγ△T / (1+n) Formula (1)

[0039] G t1-G t2 =-0.434uγ(T1-T2) / (1+n) Formula (2)

[0040] Divide formula (1) by formula (2) and rearrange to obtain:

[0041] H=(G 气 -G 母 )·(T1-T2) / (G t1 -G t2 ) formula (3);

[0042] The height of the pores can be calculated using formula (3). The grayscale is proportional to the logarithm of the exposure. The software can measure the grayscale value of each pixel and can accurately measure the slightest difference in grayscale changes.

[0043] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for measuring the pore height of a submerged arc welded steel pipe, characterized in that: The following steps are involved: S1. Preparation before measurement: determine the detection system, steel pipe specifications, and transillumination parameters; S2. Adjust the measurement software: set the number of flat panel detector frame stacking times, frame rate, offset correction, gain correction, and file storage format; S3. Static testing, obtaining images of steel pipe welds and groove comparison test blocks: Use an X-ray machine to test the steel pipe welds and groove comparison test blocks, and the flat panel detector captures and obtains digital images; S4, calibrating the geometric size of the image collected in S3: converting the image pixels into actual geometric size; S5. Use an X-ray machine to perform real-time inspection on the weld of the steel pipe, and use measurement software to record the digital imaging of the weld of the steel pipe in real time; S6. Measure grayscale values: Use software tools to change the grayscale range of the image display to achieve the best effect of human eye recognition, and measure the grayscale uniform area of ​​the weld of the submerged arc welded steel pipe, the grayscale uniform area of ​​the parent material, and the grayscale values ​​of each groove of the groove comparison test block; S7, measuring the maximum gray value of the pores to determine whether the pores are deep holes; and calculating the pore height; The method for calculating the pore height in S7 is: A1: Calculate the grayscale of pore defect contrast: G 气 -G 母 =-0.434uγ△T / (1+n) formula (1); A2: Calculate the grayscale contrast of the groove test block: G t1 -G t2 =-0.434uγ(T1-T2) / (1+n) formula (2); A3: Calculate the pore height H: The pore height H is the ratio of the pore defect contrast grayscale to the groove test block contrast grayscale. Divide formula (1) by formula (2) and arrange them to get: H = (G 气 -G 母 )·(T1-T2) / (G t1 -G t2 ) formula (3); In the formula, the height is H, the thickness difference with the base material is △T, and the average grayscale at the base material is G 母 , the maximum gray level at the pore is G 气 , the gray scale of any two grooves on the groove test block is G t1 and G t2 , the depths are T1 and T2, and u, γ, and n are assumed to be the same in the transillumination area.

2. The method for measuring the pore height of a submerged arc welded steel pipe according to claim 1, characterized in that: The groove comparison test block in S3 is provided with a plurality of grooves, and the depth of the grooves increases sequentially from one end to the other end of the groove comparison test block.

3. The method for measuring the pore height of a submerged arc welded steel pipe according to claim 1, characterized in that: In step S3, static detection is performed to obtain images of the steel pipe weld and the groove comparison test block. The groove comparison test block is located on one side of the steel pipe weld, and the steel pipe weld detection position is adjusted to the center area of ​​the detector. X-rays pass through the submerged arc welded steel pipe and form an image in real time on the flat-panel detector. The digital image is obtained using the static image capture function of the software.

4. The method for measuring the pore height of a submerged arc welded steel pipe according to claim 1, characterized in that: The method for calibrating the geometric dimensions in S4 is: collecting the groove comparison test block image, measuring the number of pixels obtained by the test block image size by software, calculating the geometric factor, and calibrating its geometric dimensions.

5. The method for measuring the pore height of a submerged arc welded steel pipe according to claim 1, characterized in that: In S7, the maximum gray value of the pore is measured to determine whether the pore is a deep hole: the maximum gray value of the pore is measured by a software tool, and the gray value is substituted into the formula to calculate the height value. When the gray value is greater than or equal to the gray value of the maximum depth groove of the groove comparison block, it can be determined as a deep hole.

6. The method for measuring the pore height of a submerged arc welded steel pipe according to claim 1, characterized in that: The maximum groove depth is the allowable pore height.

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