Method for detecting defects of total cross section of bar

Abstract

The invention relates to a bar total cross-section defect detection method, and belongs to the technical field of metal material physical and chemical detection methods. According to the technical scheme, high-frequency ultrasonic transverse waves are used for detecting defects on the surface and near the surface of a round bar, and then a conventional high-frequency ultrasonic C scanning water immersion flaw detection system is used for detecting the detection result of the defects in the bar. The method has the beneficial effects that the bar total cross-section defect distribution condition can be completely evaluated, the defect that a conventional C scanning water immersion ultrasonic detection system cannot detect near-surface and surface defects of a bar is effectively overcome, and more comprehensive and reliable nondestructive detection data are provided for solving quality problems in production.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of bar full section defect detection method, belong to the physical and chemical detection method technical field of metal material. BACKGROUND

[0002] It is found in the production detection process, using conventional high frequency water immersion ultrasonic C scanning flaw detection system only to bar interior (>8mm) defect detection, cannot effectively detect bar near surface 8mm blind area defect, cause cannot integrity evaluation bar purity's drawbacks, cannot effectively support steelmaking high purity production. SUMMARY

[0003] The present application provides a kind of bar full section defect detection method, by using high frequency ultrasonic transverse wave detection round bar surface and near surface defect, plus conventional high frequency ultrasonic C scanning water immersion flaw detection system to bar interior defect detection result, can integrity evaluation bar full section defect distribution situation, effectively solve the above problems existing in background art.

[0004] The technical scheme of the present application is: a kind of bar full section defect detection method, comprising the following steps:

[0005] (1) prepare the standard sample bar of ultrasonic transverse wave detection;

[0006] (2) prepare the sample to be detected;

[0007] (3) select appropriate high frequency flat probe, according to high frequency flat probe, select appropriate water distance, adjust high frequency flat probe offset position;

[0008] (4) according to standard sample bar, standard distance-amplitude curve, i.e. DAC curve is made;

[0009] (5) ultrasonic transverse wave detection is carried out to the sample to be detected, and the software equipment connected on flaw detection equipment records flaw detection data;

[0010] (6) the amplitude of wave amplitude in flaw detection data is compared with the amplitude of wave amplitude in DAC curve, and the surface blind area defect is judged;

[0011] (7) according to standard, select appropriate flat probe to carry out conventional high frequency water immersion ultrasonic C scanning flaw detection to bar interior defect;

[0012] (8) carry out interior ultrasonic detection to the sample to be detected, and record software equipment flaw detection data;

[0013] (9) according to SEP1927 standard, the defect to be detected in bar interior is judged.

[0014] In the step (1), the standard sample bar for ultrasonic shear wave detection is pre-prepared with defects of different depths, four long transverse holes with a diameter of 1 mm and a length of 8-15 mm are drilled on one end surface of the sample steel bar, and are distributed on the end surface of the sample bar according to a certain rule, and the hole depths are 1 mm, 3 mm, 6 mm and 8 mm respectively from the surface of the steel material.

[0015] In the step (2), the roughness of the surface of the sample is maintained at Ra≤6.3um.

[0016] In the step (3), the angle between the high-frequency flat probe ultrasonic wave incidence position and the round bar is between the first critical angle and the second critical angle, and the refraction angle β of the ultrasonic wave in the steel material is 45°, that is, K=1.

[0017] In the step (4), the DAC detection curve is made, and the maximum gain of the long transverse hole of different depth needs to be found, and the maximum echo of each long transverse hole in the standard sample bar is found by using the probe, and after finding the maximum echo of each long transverse hole, the gain is adjusted to make the echo reach 80% of the screen of the flaw detection equipment, and then the gain value is recorded, and after the four long transverse holes are found, the DAC detection curve is generated, and the DAC detection curve is saved in the software equipment.

[0018] In the step (5), during detection, the sample to be detected is placed on the roller in the water tank, the roller drives the sample to be detected to rotate in place, the water level in the water tank is higher than the distance from the high-frequency flat probe to the bottom of the water tank, the distance from the high-frequency flat probe to the steel material is calculated according to the near-field measurement of the high-frequency flat probe ultrasonic wave, and then the ultrasonic wave emitted by the high-frequency flat probe is irradiated on the sample to be detected according to the parameter setting during the sample bar debugging, and the ultrasonic wave reflected by the sample to be detected is received by the high-frequency flat probe and recorded, and then the near-surface blind area detection of the sample to be detected by the high-frequency flat probe is completed.

[0019] In the step (5), the roller rotates one circle, and the high-frequency flat probe needs to step forward 0.2-0.4 mm, that is, move 0.2-0.4 mm along the axial direction of the sample to be detected, and the speed of the roller rotation is 120 mm / s, and during detection, the standard sample bar is made according to the long transverse hole with a diameter of 1*10 mm, but in order to detect the defects of the flat bottom hole with a diameter of 1 mm equivalent, the detection sensitivity needs to be improved by adjusting the gain.

[0020] In the step (6), if the amplitude of the detection data is greater than the amplitude of the DAC detection curve, the sample to be detected is not qualified, and if the amplitude of the detection data is less than the amplitude of the DAC detection curve, the sample to be detected is qualified.

[0021] The high-frequency flat probe is a 10 MHz high-frequency flat probe, the wafer size is 6 mm, and the flaw detection equipment is a USIP40 software equipment.

[0022] The standard sample bar and the test sample are round bars of the same material and specifications.

[0023] The beneficial effects of this invention are: by using high-frequency ultrasonic shear wave to detect surface and near-surface defects of round bars, and then combining the detection results of internal defects of bars by conventional high-frequency ultrasonic C-scan water immersion testing system, the defect distribution of the entire cross section of the bar can be completely evaluated. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the shear wave standard sample block of the present invention;

[0025] Figure 2 This is a schematic diagram of the test sample of the present invention;

[0026] Figure 3 This is a schematic diagram of the end face of the sample to be tested according to the present invention;

[0027] Figure 4 This is a schematic diagram of the high-frequency water immersion ultrasonic testing method of the present invention;

[0028] Figure 5 This is a schematic diagram of subcutaneous defects in the sample to be tested according to the present invention;

[0029] Figure 6 This is a metallographic diagram of subcutaneous defects in the test sample of the present invention;

[0030] Figure 7 This is a schematic diagram of the energy spectrum of the defect in the test sample of the present invention. Figure 1 ;

[0031] Figure 8 This is a schematic diagram of the energy spectrum of the defect in the test sample of the present invention. Figure 2 ;

[0032] In the diagram: 1. High-frequency flat probe; 2. Focal length; 3. Water surface. Detailed Implementation

[0033] To make the purpose, technical solutions, and advantages of the invention's embodiments clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only a small part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0034] A method for detecting defects across the entire cross-section of a bar stock includes the following steps:

[0035] (1) Prepare a standard sample rod for ultrasonic transverse wave testing;

[0036] (2) Prepare the test sample;

[0037] (3) Select a suitable high-frequency flat probe, select a suitable water distance according to the high-frequency flat probe, and adjust the offset position of the high-frequency flat probe.

[0038] (4) Create a standard distance-amplitude curve, i.e., a DAC curve, based on the standard sample bar;

[0039] (5) Perform ultrasonic transverse wave testing on the test sample and record the flaw detection data with the software connected to the flaw detection equipment.

[0040] (6) Compare the amplitude of the flaw detection data with the amplitude of the DAC curve to determine the surface blind zone defects;

[0041] (7) Select a suitable flat probe according to the standard to perform routine high-frequency water immersion ultrasonic C-scan flaw detection on the internal defects of the bar;

[0042] (8) Perform internal ultrasonic testing on the test sample and record the flaw detection data from the software equipment.

[0043] (9) Determine the defects inside the bar according to the SEP1927 standard.

[0044] In step (1), the standard sample bar for ultrasonic transverse wave testing is prefabricated with defects of different depths. Four long transverse holes with a diameter of 1 mm and an axial length of 8-15 mm are drilled on one end face of the sample steel bar and distributed on the end face of the sample bar according to a certain pattern. The depth of the holes from the surface of the steel is 1 mm, 3 mm, 6 mm and 8 mm respectively.

[0045] In step (2), the surface roughness of the sample is maintained at Ra≤6.3um.

[0046] In step (3), the angle between the incident position of the high-frequency flat probe ultrasonic wave and the round bar is between the first critical angle and the second critical angle, and the refraction angle of the ultrasonic wave in the steel is β = 45°, i.e., K = 1.

[0047] In step (4), to create the DAC detection curve, it is necessary to find the maximum gain of long horizontal holes at different depths. The probe is used to find the maximum echo of each long horizontal hole in the standard sample rod. After finding the maximum echo of each long horizontal hole, the gain is adjusted so that the echo reaches 80% of the screen of the flaw detection device. Then the gain value is recorded. After finding all four long horizontal holes, the DAC detection curve is generated and saved in the software device.

[0048] In step (5), during the test, the sample to be tested is placed on the roller in the water tank. The roller drives the sample to be tested to rotate in place. The water level in the water tank is higher than the distance from the high-frequency flat probe to the bottom of the water tank. The distance from the high-frequency flat probe to the steel is calculated based on the ultrasonic near-field measurement of the high-frequency flat probe. Then, the ultrasonic waves emitted by the high-frequency flat probe are irradiated onto the sample to be tested according to the parameter settings during the sample bar debugging. At the same time, the high-frequency flat probe receives and records the ultrasonic waves reflected back by the sample to be tested, thereby completing the flaw detection of the near-surface blind area of ​​the sample to be tested by the high-frequency flat probe.

[0049] In step (5), for each rotation of the roller, the high-frequency flat probe needs to advance 0.2-0.4 mm, that is, move 0.2-0.4 mm along the axial direction of the test sample. The roller rotates at a speed of 120 mm / s. When the high-frequency flat probe is used for testing, since the standard sample bar is made with a long horizontal hole with a diameter of 1*10 mm, in order to detect flat bottom hole defects with a diameter equivalent of 1 mm, the detection sensitivity needs to be improved by adjusting the increment.

[0050] In step (6), if the amplitude of the wave in the flaw detection data is greater than the amplitude of the wave in the DAC detection curve, the sample to be inspected is unqualified; if the amplitude of the wave in the flaw detection data is less than the amplitude of the wave in the DAC detection curve, the sample to be inspected is qualified.

[0051] The high-frequency flat probe is a 10MHz high-frequency flat probe with a chip size of 6mm, and the flaw detection equipment is the USIP40 software device.

[0052] The standard sample bar and the test sample are round bars of the same material and specifications.

[0053] Example:

[0054] Step 1: High-frequency water immersion ultrasonic transverse wave detection of surface defects:

[0055] (1) Prepare a standard sample bar and a sample to be tested. The surface of the sample bar is processed by fine grinding, and the surface roughness is maintained at Ra≤6.3um;

[0056] (2) The standard sample bar is a 60mm section of round bar. Four long horizontal holes with a diameter of 1mm and an axial length of 10mm are drilled on one end face of the sample bar. They are distributed on the end face of the sample bar according to a certain pattern. The depth of the holes from the surface of the steel is 1mm, 3mm, 6mm and 8mm respectively.

[0057] (3) The water level in the tank is higher than the distance from the high-frequency flat probe to the bottom of the tank. The distance from the probe to the steel is calculated based on the ultrasonic near-field measurement of the high-frequency flat probe. The offset position of the high-frequency flat probe is adjusted so that the angle between the ultrasonic incident position and the round bar is between the first critical angle and the second critical angle. The ultrasonic wave in the steel is at a refraction angle β = 45°, i.e., K = 1.

[0058] (4) Create a DAC curve for the standard sample bar, find the maximum gain of the long horizontal holes at different depths, and use a high-frequency flat probe to find the maximum echo of each long horizontal hole in the standard sample bar. After finding the maximum echo of each long horizontal hole, adjust the gain so that the echo reaches 80% of the screen of the flaw detection equipment, and then record the gain value. After finding all four long horizontal holes, generate the DAC detection curve and save the DAC detection curve in the software device.

[0059] (5) Place the sample to be tested on the roller in the water tank. The roller drives the sample to be tested to rotate in place. For every 360° rotation of the roller, the high-frequency flat probe needs to move forward 0.4mm (the forward step here refers to moving 0.4mm along the axial direction of the sample to be tested). The speed of the roller rotation is 120mm / s.

[0060] (6) According to the parameter settings during the test bar debugging, the high-frequency ultrasonic transverse wave test is performed on the test sample. At the same time, the high-frequency flat probe receives and records the ultrasonic waves reflected back by the test sample, thereby completing the flaw detection of the near-surface blind area of ​​the test sample by the high-frequency flat probe.

[0061] (7) Compare the amplitude of the flaw detection data with the amplitude of the DAC curve to determine the surface blind zone defects. If the amplitude of the flaw detection data is greater than the amplitude of the DAC curve, the test sample is unqualified; if the amplitude of the flaw detection data is less than the amplitude of the DAC curve, the test sample is qualified.

[0062] (8) When using a high-frequency flat probe for testing, the standard sample rod is made with a long horizontal hole of 1*10mm in diameter. However, to detect flat-bottomed hole defects equivalent to a 1mm diameter, the decibel level needs to be increased by 2dB based on the DAC detection curve to improve detection sensitivity. The theoretical formula is: Flat-bottomed hole echo sound pressure P f For: P f =P0F S F f / λ 2 χ 2 Long transverse aperture echo sound pressure

[0063] (9) The high-frequency flat probe for ultrasonic transverse wave detection is a 10MHz high-frequency flat probe with a crystal size of 6mm, and the flaw detection equipment is a USIP40 software device.

[0064] The second step is to perform routine high-frequency water immersion ultrasonic testing.

[0065] (1) Select a suitable flat probe according to the standard to perform conventional C-scan high-frequency water immersion ultrasonic testing on the internal defects of the bar. In this example, a 10MHz high-frequency flat probe with a wafer size of 6mm is used.

[0066] (2) Select a suitable sample bar according to the specifications and size of the bar, adjust the flat probe, and set the detection parameters.

[0067] (3) Perform internal conventional C-scan high-frequency water immersion ultrasonic testing on the test sample according to the calibrated settings, and record the flaw detection data.

[0068] (4) Determine the defects to be inspected inside the bar stock, generally referring to SEP1927.

Claims

1. A method for detecting defects across the entire cross-section of a bar, characterized in that... Includes the following steps: (1) Prepare a standard sample rod for ultrasonic transverse wave testing; (2) Prepare the test sample; (3) Select a suitable high-frequency flat probe, select a suitable water distance according to the high-frequency flat probe, and adjust the offset position of the high-frequency flat probe; (4) Create a standard distance-amplitude curve, i.e., a DAC curve, based on the standard sample bar; (5) Perform ultrasonic transverse wave testing on the test sample and record the flaw detection data with the software connected to the flaw detection equipment; (6) Compare the amplitude of the flaw detection data with the amplitude of the DAC curve to determine the surface blind zone defects; (7) Select a suitable flat probe according to the standard to perform conventional high-frequency water immersion ultrasonic C-scan flaw detection on the internal defects of the bar; (8) Perform internal ultrasonic testing on the test sample and record the flaw detection data from the software equipment; (9) Determine the defects inside the bar according to the SEP1927 standard.

2. The method for detecting defects across the entire cross-section of a bar according to claim 1, characterized in that: In step (1), the standard sample bar for ultrasonic transverse wave testing is prefabricated with defects of different depths. Four long transverse holes with a diameter of 1 mm and an axial length of 8-15 mm are drilled on one end face of the sample steel bar and distributed on the end face of the sample bar according to a certain pattern. The depth of the holes from the surface of the steel is 1 mm, 3 mm, 6 mm and 8 mm respectively.

3. The method for detecting defects across the entire cross-section of a bar according to claim 1, characterized in that: In step (2), the surface roughness of the sample is maintained at Ra≤6.3um.

4. The method for detecting defects across the entire cross-section of a bar according to claim 1, characterized in that: In step (3), the angle between the incident position of the high-frequency flat probe ultrasonic wave and the round bar is between the first critical angle and the second critical angle, and the refraction angle of the ultrasonic wave in the steel is β=45°, i.e., K=1.

5. The method for detecting defects across the entire cross-section of a bar according to claim 1, characterized in that: In step (4), to create the DAC detection curve, it is necessary to find the maximum gain of long horizontal holes at different depths. The probe is used to find the maximum echo of each long horizontal hole in the standard sample rod. After finding the maximum echo of each long horizontal hole, the gain is adjusted so that the echo reaches 80% of the screen of the flaw detection device. Then the gain value is recorded. After finding all four long horizontal holes, the DAC detection curve is generated and the DAC detection curve is saved in the software device.

6. The method for detecting defects across the entire cross-section of a bar according to claim 1, characterized in that: In step (5), during the test, the sample to be tested is placed on the roller in the water tank. The roller drives the sample to be tested to rotate in place. The water level in the water tank is higher than the distance from the high-frequency flat probe to the bottom of the water tank. The distance from the high-frequency flat probe to the steel is calculated based on the ultrasonic near-field measurement of the high-frequency flat probe. Then, the ultrasonic waves emitted by the high-frequency flat probe are irradiated onto the sample to be tested according to the parameter settings during the sample bar debugging. At the same time, the high-frequency flat probe receives and records the ultrasonic waves reflected back by the sample to be tested, thereby completing the flaw detection of the near-surface blind area of ​​the sample to be tested by the high-frequency flat probe.

7. The method for detecting defects across the entire cross-section of a bar according to claim 1, characterized in that: In step (5), for each rotation of the roller, the high-frequency flat probe needs to advance 0.2-0.4 mm, that is, move 0.2-0.4 mm along the axial direction of the test sample. The roller rotates at a speed of 120 mm / s. When the high-frequency flat probe is used for testing, since the standard sample bar is made with a long horizontal hole with a diameter of 1*10 mm, in order to detect flat bottom hole defects with a diameter of 1 mm, the detection sensitivity needs to be improved by adjusting the increment.

8. The method for detecting defects across the entire cross-section of a bar according to claim 1, characterized in that: In step (6), if the amplitude of the wave in the flaw detection data is greater than the amplitude of the wave in the DAC detection curve, the sample to be inspected is unqualified; if the amplitude of the wave in the flaw detection data is less than the amplitude of the wave in the DAC detection curve, the sample to be inspected is qualified.

9. The method for detecting defects across the entire cross-section of a bar according to claim 1, characterized in that: The high-frequency flat probe is a 10MHz high-frequency flat probe with a chip size of 6mm, and the flaw detection equipment is the USIP40 software device.

10. The method for detecting defects across the entire cross-section of a bar according to claim 1, characterized in that: The standard sample bar and the test sample are round bars of the same material and specifications.

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