UT detection process for 9Ni steel full penetration welding joint

Abstract

The invention discloses a UT detection process for a 9Ni steel full penetration welding joint, which comprises the following steps of: selecting a probe and a wedge block; detecting a base material: selecting a single or bicrystal normal probe with the frequency of 2-5MHz, and controlling the diameter of a wafer to be phi 10mm-phi 25mm; for the steel plate with the nominal thickness less than 35mm, using a double-crystal probe, and adjusting a focusing area to adapt to the thickness of the plate to be inspected; a longitudinal wave bicrystal focusing angle probe in direct contact with high-damping narrow pulses is adopted, and the angles of the probe are 70 degrees, 60 degrees and 45 degrees; the method has the beneficial effects that by optimizing the steps of probe selection, coupling agent use, test block manufacturing and the like, the detection precision and efficiency are remarkably improved; meanwhile, the technology has the advantages of being easy and convenient to operate, wide in application range and the like, and powerful guarantee is provided for quality control of the 9Ni steel welded joint; the UT detection requirements of classification societies on the 9Ni steel full penetration welding joints are met, and the blank of the UT detection technology for the 9Ni steel full penetration welding joints at home and abroad is filled.

Description

Technical Field

[0001] The invention belongs to the technical field of detection technology, and in particular relates to a UT detection technology for a 9Ni steel full penetration welded joint. Background Art

[0002] As a single austenitic material, the 9Ni steel full penetration welded joint uses face-centered cubic austenite as the matrix from room temperature to high temperature. Unlike ordinary carbon steel and alloy steel, which can undergo phase transformation through heat treatment, the grain size cannot be adjusted through heat treatment, resulting in coarse grains after performance heat treatment, and the grains are coarse and uneven. During UT detection, the wave is scattered greatly, causing serious signal attenuation and low signal-to-noise ratio, which is not conducive to the location of defects.

[0003] At present, the testing standard system specifically for 9Ni has not been established and improved. There are no clear regulations on equipment, probes, coupling agents, scanning methods, standard test blocks, comparison test blocks, sensitivity adjustment methods, etc. Some literature materials propose that the sensitivity can be adjusted by using comparison test blocks with the same material and state as the workpiece to be tested or artificial holes on the workpiece, but there is no requirement for the size of the hole. Summary of the invention

[0004] The purpose of the present invention is to provide a UT detection process for a 9Ni steel full penetration welded joint, which meets the UT detection requirements of a classification society for a 9Ni steel full penetration welded joint.

[0005] To achieve the above object, the present invention provides the following technical solution: UT detection process of 9Ni steel full penetration welded joint, comprising the following steps:

[0006] Probe and Wedge Selection:

[0007] Parent material inspection: Use a single or dual crystal straight probe with a frequency between 2-5MHz and a crystal diameter of 10mm to 25mm. For steel plates with a nominal thickness of less than 35mm, use a dual crystal probe and adjust the focus area to suit the thickness of the plate to be inspected.

[0008] Weld detection: Use a high-damping narrow pulse direct contact longitudinal wave double crystal focusing oblique probe with probe angles of 70°, 60° and 45°; select the best probe angle based on the lack of fusion between the weld and the base material to ensure that the incident wave is perpendicular to the weld bevel;

[0009] Gap control between test surface and probe:

[0010] The gap does not exceed 0.5mm; for cylindrical or spherical surfaces, according to the formula g = a 2 / D adjustment, where D is the diameter of the component and a is the size of the probe wedge in the scanning direction;

[0011] Choice of coupling agent:

[0012] The coupling medium performance meets the requirements of EN583-1 and can be fluid or paste-like oil, fat, glycerin or paste; the coupling agent used for calibration of the instrument is the same as that used for on-site testing, and the sulfur content does not exceed 1% by weight;

[0013] Test block production and requirements:

[0014] IIW-V2 test block or CSK-IA test block is made of nickel-based alloy steel with the same acoustic properties as the test object material, which is used for straight / oblique probe range calibration, oblique probe angle measurement and probe-instrument combination performance test;

[0015] The thickness deviation between the comparison test block and the inspected workpiece shall not exceed 10% of the thickness of the inspected workpiece or 3mm;

[0016] Drill side holes of different depths on the comparison test block, establish the DAC curve, and determine the transmission correction value;

[0017] Testing process technical requirements:

[0018] The inspection range includes the weld and the width of the base material or heat-affected zone within at least 10mm on both sides of the weld;

[0019] The inspection surface is flat, with no foreign matter affecting the probe coupling, and the corrugation does not exceed 0.5mm;

[0020] When evaluating the test results, the maximum allowable gap of the test surface is 0.5mm;

[0021] Testing process:

[0022] Parent material inspection: Use a straight probe to inspect the parent material in the detection area before and after welding to calibrate sensitivity; report defects with a cross-section larger than the beam and measure the defect range using the 6dB method;

[0023] Weld inspection: Select the probe and scanning method according to the weld type to detect transverse and longitudinal defects;

[0024] Detection range and sensitivity settings:

[0025] Range and sensitivity settings were performed before and after each test;

[0026] The DAC curve made with the 3mm horizontal hole on the comparison test block is used as the reference standard, and the evaluation level is the reference level -14dB;

[0027] Show results of the evaluation:

[0028] All display positions are defined by a coordinate system, and a point on the test surface is selected as the measurement origin; for multiple surface tests, reference points are established and positional relationships are determined;

[0029] For girth welds, determine the inner and outer reference points.

[0030] As a preferred technical solution of the present invention, the best probe angle is selected according to the lack of fusion between the weld and the base material to ensure that the incident wave is perpendicular to the weld bevel; if the calculated angle does not meet the standard probe angle, the nearest large angle is selected.

[0031] As a preferred technical solution of the present invention, according to the formula g=a 2 / D adjustment, where D is the component diameter and a is the size of the probe wedge in the scanning direction; if g>0.5mm, the probe wedge needs to be trimmed to adapt to the surface, and the detection sensitivity and scanning range need to be adjusted.

[0032] As a preferred technical solution of the present invention, the comparison test block includes a weld of thickness, material, welding process, weld shape and structure, and the thickness deviation from the inspected workpiece is no more than 10% or 3 mm of the thickness of the inspected workpiece.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] By optimizing the steps of probe selection, coupling agent use, test block preparation, etc., the detection accuracy and efficiency are significantly improved; at the same time, the process has the advantages of simple operation and wide application range, which provides a strong guarantee for the quality control of 9Ni steel welded joints; it meets the classification society's UT detection requirements for 9Ni steel full penetration welded joints, and fills the gap in UT detection technology for 9Ni steel full penetration welded joints at home and abroad. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The probe angle diagram selected for detecting the lack of fusion of the side wall according to the present invention, α=90°-β, wherein α is the probe angle and β is the groove angle;

[0036] Figure 2 A comparative test block of the present invention is made of a 9Ni base material with a thickness of 40 mm, and side horizontal holes with a diameter of 3 mm are drilled at different depths;

[0037] Figure 3 The invention measures the attenuation difference between the echo of the transverse hole of different depths passing only through the base material and passing through the base material plus the weld on the weld comparison test block, and takes the maximum value as the transmission correction value and adds it to the gain. Figure 1 ;

[0038] Figure 4The invention measures the attenuation difference between the echo of the horizontal hole of different depths passing only through the base material and passing through the base material plus the weld on the weld comparison test block, and takes the maximum value as the transmission correction value and adds it to the gain. Figure 2 ;

[0039] Figure 5 The invention measures the attenuation difference between the echo of the horizontal hole of different depths passing only through the base material and passing through the base material plus the weld on the weld comparison test block, and takes the maximum value as the transmission correction value and adds it to the gain. Figure 3 ;

[0040] Figure 6 It is a schematic diagram of the probe angle and focal length of the present invention;

[0041] Figure 7 The invention uses an oblique probe to scan the weld from two sides;

[0042] Figure 8 The invention uses an oblique probe to scan from one side of two sides of the weld, and uses a straight probe to scan from the panel;

[0043] Fig. 9 It is a coordinate system diagram of the present invention. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Example 1

[0046] See also Figure 1-Figure 9 , which is the first embodiment of the present invention, provides a UT detection process for a full penetration welded joint of 9Ni steel, comprising the following steps:

[0047] Personnel qualification requirements:

[0048] Personnel who conduct non-destructive testing must obtain a certificate issued by a nationally recognized non-destructive testing training system, including CCS, China General Administration of Quality Supervision, Inspection and Quarantine, and PCN. Personnel who conduct non-destructive testing should be familiar with the welding process of related components, understand the organizational characteristics of nickel-steel welds, master the propagation characteristics of ultrasonic waves in nickel-steel welds, and be able to give correct analysis and judgment of various signals that may appear during testing.

[0049] Technical requirements of the equipment:

[0050] The instrument used for ultrasonic testing must comply with the requirements of ISO 22232;

[0051] Probes and Wedges

[0052] For parent material testing: generally use a single or dual crystal straight probe with a frequency between 2-5Mz, and a crystal diameter of 10mm to 25mm; when testing steel plates with a nominal thickness of less than 35mm, a dual crystal probe should be used; the focusing area of ​​the dual crystal probe should be adapted to the thickness of the plate to be inspected;

[0053] Weld detection: A high-damping narrow pulse direct contact longitudinal wave dual crystal focusing oblique probe should be used, with probe angles of 70°, 60° and 45°; when detecting the lack of fusion between the weld and the base material, the best probe angle is the angle that makes the incident wave perpendicular to the weld bevel; the best angle for V-shaped groove welds is given and calculated by the groove geometry, such as Figure 1 As shown; If the calculated angle does not conform to any standard probe angle, the nearest larger probe angle should be selected, provided that there is no other reason to select a smaller probe angle; When two or more angle probes are specified, the difference between the nominal beam angles should be 10° or greater; The frequency of the probe is usually between 2.0 and 4.0 MHz; In the case of short sound path, a small probe is used, and the diameter of the chip is 6 to 12 mm (or a rectangle of equivalent area); For long sound paths, such as straight probe sound paths greater than 100 mm or oblique probe sound paths greater than 200 mm, a large probe is used, and the diameter of the chip is 12 to 24 mm (or a rectangle of equivalent area);

[0054] For rectangular wafer sizes, it is recommended to select the wafer sizes related to material thickness described in Table 1;

[0055] Table 1: Material thickness and related wafer dimensions

[0056] Material thickness t[mm] <![CDATA[Chip size [mm 2 > 10 to 15 60～100 15 to 35 100～200

[0057] The gap between the test surface and the probe cannot exceed 0.5mm; if it is a cylindrical or spherical surface, it generally needs to meet the following formula:

[0058] g = a 2 / D

[0059] Where: D = diameter of the component, in mm;

[0060] a = the size of the probe wedge in the scanning direction;

[0061] When g>0.5mm, the probe wedge should be trimmed to adapt to the surface, and the detection sensitivity and scanning range should also be adjusted accordingly;

[0062] Couplant:

[0063] The performance of the coupling medium meets the requirements of EN583-1 and can be fluid or paste-like oils, fats, glycerin or pastes; the coupling agent used when calibrating the instrument should be the same as the coupling agent used in on-site testing; if different coupling agents are used, a comparative verification should be carried out to determine the coupling difference between the two, and the dB value should be increased (or decreased) during the test; the sulfur content of the coupling medium should not exceed 1% by weight;

[0064] Test block:

[0065] IIW-V2 test blocks or CSK-IA test blocks made of nickel-based alloy steel with the same acoustic properties as the test object material can be used for calibration of straight / oblique probe range and determination of oblique probe angle, as well as testing of probe-instrument combination performance.

[0066] Comparison test block requirements:

[0067] The comparison block used for sensitivity setting must contain a weld with typical thickness, material, welding process, weld shape and structure, and surface condition;

[0068] The deviation between the thickness of the comparison test block and the thickness of the workpiece under test shall not exceed 10% of the thickness of the workpiece under test or 3 mm, whichever is greater;

[0069] Drill 3mm diameter side holes at the center of the weld at 1 / 4T, 1 / 2T, 3 / 4T and 2mm from the bottom of the test block. If necessary, add 3mm diameter side holes at other depths.

[0070] A 40mm thick 9Ni base material was used to make a comparison test block. Side holes with a diameter of 3mm were drilled at different depths. Figure 2 ; Use this test block to establish a DAC curve, and measure the attenuation difference between the cross hole echo of different depths passing only through the base material and passing through the base material plus the weld on the weld comparison test block. Take the maximum value as the transmission correction value and add it to the gain. Figure 3 , 4 , 5;

[0071] Testing process technical requirements:

[0072] The inspection range includes the weld and the parent material within a range of at least 10 mm on both sides of the weld, or refers to the width of the heat-affected zone, whichever is larger;

[0073] Regardless of the conditions, the entire inspection range should be inspected; if individual areas within the range cannot be inspected by more than one inspection angle, other ultrasonic inspection techniques or other non-destructive methods can be used to supplement them; therefore, in some cases, it is necessary to remove excess parent material;

[0074] Supplementary methods may require testing with dual crystal angled detectors, waveform detectors, more ultrasonic techniques, or other appropriate methods (e.g., liquid penetrant, magnetic particle inspection, radiometric testing); when selecting alternative or compensatory methods, the weld type and the detection location of the defect to be detected must be considered;

[0075] The inspection surface should be wide enough to ensure that the entire inspection range can be fully covered; if the inspection can be carried out from the upper and lower planes of the weld, and the inspection coverage is equivalent to the inspection range, the width of the inspection surface can also be reduced;

[0076] The inspection surface must be flat and free of any foreign matter that may affect probe coupling (such as rust, scale, welding spatter, notches and grooves, etc.); the waviness of the inspection surface must not cause the gap between the probe and the test surface to be greater than 0.5 mm. If necessary, it can be polished as required. Local changes in the inspection surface (such as along the edge of the weld) will cause the gap under the probe to expand to 1 mm, but local changes are allowed if and only if there are more than one other probe angle from the affected side of the weld; these additional inspection angles can compensate for the reduction in weld coverage due to the expansion of the gap;

[0077] In any case, the maximum allowable gap of the test surface for evaluation of the test results is 0.5mm; if the surface finish Ra of the machined surface is not greater than 6.3μm, or the surface finish of the shot peening treatment is not greater than 12.5μm, it can be considered that the surface of the flaw detection surface and the surface with good beam reflection effect meet the requirements;

[0078] Testing process:

[0079] Parent material testing requirements:

[0080] Before or after welding, the parent material in the detection area should be detected with a straight probe, unless it can be shown that material defects or high attenuation will not affect the detection of the probe (such as detection during the manufacturing process); sensitivity calibration should be performed on the parent material without defects; the secondary back echo should be adjusted to 75% of the full screen height FSH; defects with a cross-section larger than the beam (bottom wave disappearance) should be reported; when the bottom wave disappears completely, the range of the defect is measured using the 6dB-method;

[0081] Once a defect occurs, its impact on the angled ultrasonic beam test must be estimated, and if necessary, the technical process must be adjusted accordingly; if the coverage of ultrasonic flaw detection is seriously affected, other detection methods (such as X-ray detection) can also be considered through consultation;

[0082] Detection range and sensitivity settings:

[0083] Range and sensitivity settings should be made before each test and should be checked at least every 4 hours and after the test. These settings should also be checked if there is any suspicion that system parameters or equivalent settings have changed.

[0084] If any deviation is detected, it should be corrected according to Table 2;

[0085] Table 2: Sensitivity and range corrections

[0086]

[0087] Reference level:

[0088] The distance amplitude curve (DAC curve) made with the 3mm horizontal hole on the comparison test block specified in the test block regulations is used as the reference standard;

[0089] Rating:

[0090] The rating level is the reference level -14dB;

[0091] Transmission correction:

[0092] Since the longitudinal wave angle probe can only be used for 1 / 2 span, it is impossible to make transmission corrections; therefore, the calibration block must have a surface processing state similar to that of the production material;

[0093] Show results of the evaluation:

[0094] Display location:

[0095] All displayed positions are represented by a coordinate system (such as Fig. 9 As shown in the figure, a point on the test surface is selected as the original point of measurement;

[0096] If testing is to be done on more than one surface, then reference points should be established on each surface; in this case, care should be taken to establish a positional relationship between all reference points used, so that the absolute position of all indications can be determined with respect to any given reference point;

[0097] For circumferential welds, it is required to determine the inner and outer reference points before welding assembly.

[0098] Example 2

[0099] See also Figure 1-Figure 9 , which is the second embodiment of the present invention, is based on the previous embodiment, except that:

[0100] Detection range and scanning technology:

[0101] The selection of probe angle and focal length is based on Figure 6As shown;

[0102] Detection of longitudinal defects:

[0103] For butt welds, if possible, use an angle probe to scan from both sides of the weld, such as Figure 7 As shown in the figure, if the weld can only be scanned from one side due to conditions, the weld excess height needs to be ground flat and the weld should be scanned using a straight probe;

[0104] For T-type welds, use an angled probe to scan from one side of the weld and a straight probe to scan from the panel. Figure 8 Shown

[0105] Detecting transverse imperfections using an angle probe:

[0106] If the surface of the weld joint is smooth enough, the probe can be placed on the surface to detect transverse defects along the center line of the joint; or the probe can be scanned along both sides of the weld joint with the beam forming a small angle with the center line. In all cases, the scan should be performed in both directions on both sides of the weld.

[0107] Show results of the assessment:

[0108] The evaluation of all relevant display results above the evaluation standard shall be carried out in accordance with the provisions of the maximum echo amplitude and display length;

[0109] Maximum echo amplitude:

[0110] The echo amplitude can be maximized based on the movement of the probe and recorded against an agreed reference standard;

[0111] Display Length:

[0112] Whenever possible, the displayed length (either longitudinally or transversely) should be determined using an absolute sensitivity technique above the rating level;

[0113] Acceptance criteria:

[0114] For example, if the acceptance criteria refer to ISO 11666 level 2;

[0115] All defect echoes exceeding the assessment line must be qualitatively characterized. If the defect is characterized as a surface defect (such as cracks, lack of fusion and lack of penetration), it is unqualified;

[0116]

[0117]

[0118] Although the embodiments of the present invention have been shown and described, as detailed above, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. 9 UT testing process for full penetration welded joints of Ni steel, characterized by: The steps include: Probe and Wedge Selection: Parent material inspection: Use a single or dual crystal straight probe with a frequency between 2-5MHz and a crystal diameter of 10mm to 25mm. For steel plates with a nominal thickness of less than 35mm, use a dual crystal probe and adjust the focus area to suit the thickness of the plate to be inspected. Weld detection: Use a high-damping narrow pulse direct contact longitudinal wave double crystal focusing oblique probe with probe angles of 70°, 60° and 45°; select the best probe angle based on the lack of fusion between the weld and the base material to ensure that the incident wave is perpendicular to the weld bevel; Gap control between test surface and probe: The gap does not exceed 0.5mm; for cylindrical or spherical surfaces, according to the formula g = a 2 / D adjustment, where D is the diameter of the component and a is the size of the probe wedge in the scanning direction; Choice of coupling agent: The coupling medium performance meets the requirements of EN583-1 and can be fluid or paste-like oil, fat, glycerin or paste; the coupling agent used for calibration of the instrument is the same as that used for on-site testing, and the sulfur content does not exceed 1% by weight; Test block production and requirements: IIW-V2 test block or CSK-IA test block is made of nickel-based alloy steel with the same acoustic properties as the test object material, which is used for straight / oblique probe range calibration, oblique probe angle measurement and probe-instrument combination performance test; The thickness deviation between the comparison test block and the inspected workpiece shall not exceed 10% of the thickness of the inspected workpiece or 3mm; Drill side holes of different depths on the comparison test block, establish the DAC curve, and determine the transmission correction value; Testing process technical requirements: The inspection range includes the weld and the width of the base material or heat-affected zone within at least 10mm on both sides of the weld; The inspection surface is flat, with no foreign matter affecting the probe coupling, and the corrugation does not exceed 0.5mm; When evaluating the test results, the maximum allowable gap of the test surface is 0.5mm; Testing process: Parent material inspection: Use a straight probe to inspect the parent material in the detection area before and after welding to calibrate sensitivity; report defects with a cross-section larger than the beam and measure the defect range using the 6dB method; Weld inspection: Select the probe and scanning method according to the weld type to detect transverse and longitudinal defects; Detection range and sensitivity settings: Range and sensitivity settings were performed before and after each test; The DAC curve made with the 3mm horizontal hole on the comparison test block is used as the reference standard, and the evaluation level is the reference level -14dB; Show results of the assessment: All display positions are defined by a coordinate system, and a point on the test surface is selected as the measurement origin; for multiple surface tests, reference points are established and positional relationships are determined; For girth welds, determine the inner and outer reference points.

2. The UT detection process of 9Ni steel full penetration welded joint according to claim 1 is characterized in that: According to the lack of fusion between the weld and the base material, select the best probe angle to ensure that the incident wave is perpendicular to the weld bevel; if the calculated angle does not meet the standard probe angle, select the nearest large angle.

3. The UT testing process for 9Ni steel full penetration welded joints according to claim 1 is characterized in that: According to the formula g = a 2 / D adjustment, where D is the component diameter and a is the size of the probe wedge in the scanning direction; if g>0.5mm, the probe wedge needs to be trimmed to adapt to the surface, and the detection sensitivity and scanning range need to be adjusted.

4. The UT testing process for 9Ni steel full penetration welded joints according to claim 1, characterized in that: The comparison test block includes the weld of thickness, material, welding process, weld shape and structure, and the thickness deviation from the inspected workpiece is not greater than 10% of the thickness of the inspected workpiece or 3mm.

5. The UT testing process for 9Ni steel full penetration welded joints according to claim 1, characterized in that: The weld types include butt welds and T-welds.

6. The UT testing process for 9Ni steel full penetration welded joints according to claim 1, characterized in that: For the comparison test block, side transverse holes with a diameter of 3 mm were drilled at 1 / 4T, 1 / 2T, 3 / 4T and the center of the weld 2 mm away from the bottom surface.

7. The UT testing process for 9Ni steel full penetration welded joints according to claim 1, characterized in that: Before and after welding, the straight probe is used to detect the parent material in the detection area for sensitivity calibration; the secondary back echo is adjusted to 75% of the full screen height FSH, and defects with a cross-section larger than the beam are reported.

8. The UT testing process for 9Ni steel full penetration welded joints according to claim 1 is characterized in that: Set the range and sensitivity before and after each test and check these settings at least every 4 hours and after the test.

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