JB/T 8467-1996 Ultrasonic flaw detection method for forged steel parts
Some standard content:
JB/T8467—
This standard is not equivalent to ASTMA388
84 "Standard for Ultrasonic Flaw Detection Method of Large Forged Steel Parts". This standard strives to ensure the consistency of flaw detection results by specifying the testing equipment, testing requirements and testing methods. The quality grade classification of large forged steel parts is too different in quality requirements, so it is not appropriate to make unified regulations in this standard. The quality acceptance of forgings shall be negotiated and resolved by the supply and demand parties based on technical requirements. This standard was proposed and managed by the Deyang Large Casting and Forging Research Institute of the Ministry of Machinery Industry. Drafting unit of this standard: Taiyuan Heavy Machinery Group Corporation Main drafter of this standard: Song Shulin
1 Scope
Machinery Industry Standards of the People's Republic of China
Ultrasonic Flaw Detection Method of Forged Steel Parts
This standard specifies the ultrasonic flaw detection method of forged steel parts using the longitudinal or transverse wave contact pulse reflection method. JB/T 8467.-96
This standard is applicable to carbon steel and low alloy steel forgings with a thickness or diameter equal to or greater than 100mm. Ultrasonic flaw detection of austenitic stainless steel forgings can also be implemented as a reference.
Cited Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T12604.190 Nondestructive testing terminology Ultrasonic testing JB4126--84 Manufacture and control of steel test blocks for ultrasonic testing JB4730-94 Nondestructive testing of pressure vessels
ZBY230--84 General technical conditions for A-type pulse reflection ultrasonic flaw detector 7.BY231--84 Test method for the performance of probes for ultrasonic flaw detection 3 Definitions
In addition to the root saw GB/T12604.1, the following definitions are also used in this standard. 3.1 Equivalent diameter
Under the same conditions, the amplitude of the defect echo is equal to the echo amplitude of a flat-bottomed hole of a certain diameter perpendicular to the ultrasonic beam. This diameter is called the defect equivalent diameter, referred to as the equivalent diameter. 3.2 Continuous defect echo
The equivalent diameter of the defect is not less than 2mm at a certain distance, and the fluctuation range of the echo is not greater than 2dB within the spacing of the probe continuous movement distance equal to or greater than 30mm. 3.3 Dense defects
There are five or more defect echoes in a cube with a side length less than or equal to 50mm. Note: Translated from 8.1.3.2 in ASTM A388/A388M--84. 3.4 Bottom reduction Bc/B (dB)
The dB difference between the first bottom wave amplitude B. value of the intact area without defects and the first bottom wave amplitude B value of the defective area. Note: According to 3.2 in JB473094.
3.5 Single defect echobzxZ.net
The defect echo with a spacing greater than 50mm and an equivalent diameter of not less than 2mm. 3.6 Scattered defect echoes
In a square body with a side length of 50mm, the number of defect echoes is less than five, and the equivalent diameter of the defect is not less than 2mm. 3.7 Moving defect echoes
When the probe is moved on the surface of the forging, the front movement distance of the defect echo is equivalent to the defect echo of 25mm or more of the thickness of the forging L. Approved by the Ministry of Machinery Industry of the People's Republic of China on September 3, 1996 and implemented on July 1, 1997
4 Technical requirements
4.1 General requirements
JB/T8467-96
4.1.1 Personnel engaged in ultrasonic flaw detection of large forged steel parts shall have certain basic knowledge of smelting, forging and heat treatment and experience in forging flaw detection, and shall be qualified by the recognized relevant departments and obtain the corresponding grade qualification certificate before they can engage in ultrasonic flaw detection of forgings. 4.1.2 The forging surface to be inspected shall not have any attachments that may affect the sensitivity of the inspection, such as paint, scale, dirt, etc. 4.1.3 The surface roughness Ra value of the forging inspection surface shall not be greater than 6.3um. 4.1.4 Forging inspection shall be carried out on two inspection surfaces perpendicular to each other, and the entire forging shall be scanned as much as possible. For pie-shaped and rectangular forgings, the inspection surfaces shall be selected on two perpendicular surfaces. For shaft forgings, radial inspection shall be carried out on the outer cylindrical surface, and axial inspection shall be carried out on the end face of the shaft when necessary.
4.1.5 The steel comparison test block for forging inspection
shall comply with the provisions of JB4126.
4.1.5.1 The plane comparison test block of the longitudinal wave straight probe shall use CS-1 and CS-2 test blocks, or it can be processed by itself. Its shape and size shall comply with the provisions of the relevant standards. When inspecting curved surfaces, the curved surface comparison test block used is shown in Figure 1. R5mm
Note: R is 0.9～1.5 of the radius of the curved surface of the T piece. murs
Curved surface comparison test block
4.1.5.2 The comparison test block of the shear wave oblique probe shall be made of forgings with the same or similar chemical composition, heat treatment conditions, surface roughness, curvature, etc. as the forgings to be tested.
4.1.5.3 The inner wall of the comparison test block for hollow forgings shall be cut into a rectangular or 60V-shaped groove parallel to the axis, with a length of 25mml. The test block with a groove depth of 3% of the forging thickness is recommended. The test block with a maximum groove depth of no more than 6mm. 4.2 Flaw detection equipment and probe
4.2.1 The flaw detection equipment shall comply with the provisions of ZBY230. 4.2.1.1 The working frequency of the flaw detector shall be at least 1~5MHz, and the accuracy of the attenuator shall be within any adjacent 12dB, and the error shall be within ±］dB. The total adjustment amount shall be greater than 60dB.
4.2.1.2 The vertical linearity of the flaw detector shall be at least within 75% of the screen height, and its error shall be less than 5%. The horizontal linearity error shall not be greater than 2%
4.2.1.3 When the longitudinal wave straight probe detects a flaw with a depth of 200nm and a flat bottom hole, the sensitivity margin shall not be less than 40d13, and the far field resolution shall be greater than or equal to 30dB.
4.2.2 The probe shall comply with the provisions of ZBY231. 4.2.2.1 The chip diameter of the longitudinal wave straight probe is 12~28mm, and the maximum effective area of the inclined probe chip is 25mm×25mm. All probes shall be used at the nominal frequency, and the frequency error shall not exceed ±10% of the nominal value. 324
JB/T 8467-96
4.2.2.2 The remaining parameters of the probe shall comply with the provisions of ZBY231. 4.3 The coupling agent is recommended to be oil, glycerin, and organic paste. Other coupling agents may also be used without affecting the sensitivity of the flaw detection. 5 Flaw detection requirements
5.1 In principle, forgings should be ultrasonically inspected after the final heat treatment. If the forgings are to be drilled, grooved, tapered, and other processing steps before the heat treatment, which affects the flaw detection, the forgings can also be ultrasonically inspected before this processing step. After the heat treatment, all detectable parts must be 100% re-inspected.
5.2 The scanning speed of the probe should not exceed 150mm/s. 5.3 The probe movement should overlap and cover at least 15% of the wafer width each time. 5.4 When re-inspecting or re-evaluating the forgings, comparable flaw detection conditions should be selected. 6 Flaw detection method
6.1 Longitudinal wave flaw detection
6.1.1 The flaw detection frequency is usually 1~~5MHz, and the recommended flaw detection frequency for general forgings is 2~2.5MHz. 6.1.2 In principle, the adjustment of flaw detection sensitivity is recommended by the bottom echo reflection method. Due to the limitations of the geometric shape and size of the forging, the comparison test block method can also be used for adjustment.
6.1.3 Adjustment by bottom echo reflection method
Place the probe on the flaw detection surface where the incident surface and the reflection surface of the forging are parallel, and there are no defects and boundary reflection waves. Adjust the sensitivity knob of the flaw detector to adjust the bottom echo to 40% to 80% of the screen height, and then adjust the gain value of the forging according to the following calculation formula: a) Gain value of solid forgings
Where: AdB. Gain value to be increased, dB; AdB = 20lg
T Detection thickness or diameter of forging, mm;
—Required flaw detection sensitivity flat bottom hole diameter, mm: ^—Wavelength, mm.
b) Gain value of forgings with center holes
AdB = 20lg
Where: D-Outer diameter of the forging part to be detected, mm; d
-Inner diameter of the forging part to be detected, mm.
6.1.4 Sensitivity adjustment by comparison test block method
6.1.4.1 The material, surface roughness and heat treatment conditions of the comparison test block used should be the same or similar to those of the forging to be tested. 6.1.4.2 Use CS-1 or CS-2 comparison test blocks or other test blocks with equivalent effects to make adjustments. (1)
6.1.4.3 Adjust the reflected wave of the flat-bottom hole of the CS test block selected in 6.1.4.2 to 40%~80% of the screen height, 6.1.5 When calculating the defect equivalent, if the material attenuation of the forging exceeds 4dB/m, correction should be made. The attenuation coefficient is determined according to formula (3): α(BB2) 6 dB
Where: B, dB value of the secondary bottom echo
B dB value of the secondary bottom echo;
T-thickness of the forging, mm;
Attenuation coefficient, dB/mm.
6.1.6 When inspecting forgings, pay attention to the parts where the bottom echo is significantly reduced, and find out the reasons for the reduction of the bottom echo. Any area where the bottom echo is significantly reduced should be re-inspected.
6.2 Shear wave flaw detection
JB/T 8467 -— 96
6.2.1 Shear wave flaw detection is mainly used for annular or hollow forgings, whose axial length should be greater than 50mm and the ratio of outer diameter to inner diameter should be less than 2:16.2.2 If the ratio of outer diameter to inner diameter of the forging or the geometric shape of the forging does not affect the required flaw detection sensitivity, an oblique probe with a refraction angle of 45 is used for flaw detection. In order to use an oblique probe to detect hollow forgings with an outer diameter to inner diameter ratio of 2:1, a curved wedge or contact block can be added to the probe to form the required waveform and angle to achieve the required sensitivity. 6.2.3 Calibration of shear wave flaw detection sensitivity
From the outer circle, detect the rectangular or 60° V-shaped groove on the inner wall parallel to the axial direction of the forging to obtain a full screen height of 60%. It can also be calibrated using a separate comparison test block. The production and selection of the comparison test block should meet the requirements of 4.1.5. If the forgings are produced in batches, one of them is taken to make a reference piece for calibration. A groove is cut on its inner wall. The groove depth is 3% of the maximum thickness of the workpiece, but the maximum depth shall not exceed 6mm. The groove length is 25mm. The thickness of the reference piece should be the same as that of the tested piece. Under the same instrument conditions, a reflection echo is obtained from a similar groove on the outer circle. A comparison amplitude line is drawn through the peak of the inner and outer grooves. If possible, it is best to cut the groove directly on the test piece or the remaining material. In actual flaw detection, the groove on the outer circle may not be detected from the outer circle surface. If feasible (some forgings have a small inner diameter and cannot be flawed), flaw detection should be carried out from the inner and outer surfaces, and the groove on the inner surface is detected on the outer surface, and the groove on the outer surface is detected on the inner surface. When necessary and possible, curved wedges or contact blocks can also be used for flaw detection.
6.3 Readjustment of flaw detection sensitivity
6.3.1 During the flaw detection of forgings, if there is any change in the probe, coupling agent, or instrument setting value, the flaw detection sensitivity must be readjusted. 6.3.2 The sensitivity of forgings should be checked at least once during the flaw detection process. The sensitivity of flaw detection should be checked after the flaw detection is completed. When the flaw detection sensitivity changes by more than 2dB, the flaw detection sensitivity should be readjusted. Forgings tested before this should be retested. 7 Measurement and Recording
7.1 The quantification of longitudinal wave defects adopts the equivalent method, and the shear wave adopts the percentage method. 7.2 When the single or scattered defect echo has an equivalent diameter greater than or equal to the flaw detection sensitivity, it should be recorded. 7.3 Record the dense defect echo according to the technical requirements, and mark the location and distribution range of the defect. 7.4 Record the equivalent diameter, location and distribution range of the floating defect echo. 7.5 Record the location and distribution range where the bottom echo is severely reduced or disappears. 7.6 For shear wave flaw detection, record the location and distribution range of the defect echo that is not less than 60% of the bat amplitude of the comparison slot echo. 8. Detection report
The detection report shall include the following contents:
8.1 Name, material, dimension diagram, detection position, and roughness of the detection surface of the forging. 8.2 Date of commission, commissioning unit, and commission number. 8.3 Detection conditions: model of the flaw detector, frequency of the probe, size of the wafer, K value and β value of the oblique probe. 8.4 Detection sensitivity, name of the coupling agent, and model of the comparison test block. 8.5 Detection results and evaluation level.
8.6 Name, qualification certificate, and qualification level of the detector, and name, qualification certificate number, level, and date of the reviewer.
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