1、Designation: A531/A531M 12A531/A531M 13Standard Practice forUltrasonic Examination of Turbine-Generator Steel RetainingRings1This standard is issued under the fixed designation A531/A531M; the number immediately following the designation indicates the yearof original adoption or, in the case of revi
2、sion, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice covers ultrasonic examination of turbine-generator retaining rings produced in accord
3、ance with SpecificationsA288 and A289/A289M with an inside diameter to wall thickness ratio equal to or greater than 5:1 and with wall thicknesses from1 to 4 in. 25 to 102 mm.1.2 Forgings may be inspected by either the contact or the immersion methods, or combinations thereof, as agreed upon between
4、the manufacturer and the purchaser.1.3 Supplementary requirements of an optional nature are provided for use at the option of the purchaser. The supplementaryrequirements shall apply only when specified individually by the purchaser in the purchase order or contract.1.4 This practice is expressed in
5、 inch-pound and SI units; however, unless the purchase order or contract specifies the applicable“M” specification designation (SI units), the inch-pound units shall apply. The values stated in either inch-poundSI units orSIinch-pound units are to be regarded separately as standard. Within the pract
6、ice, the SI units are shown in brackets. The valuesstated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combiningvalues from the two systems may result in nonconformance with the standard.1.5 This standard does not purport to address al
7、l of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A288 Specification for
8、 Carbon and Alloy Steel Forgings for Magnetic Retaining Rings for Turbine GeneratorsA289/A289M Specification for Alloy Steel Forgings for Nonmagnetic Retaining Rings for GeneratorsE127 Practice for Fabricating and Checking Aluminum Alloy Ultrasonic Standard Reference BlocksE317 Practice for Evaluati
9、ng Performance Characteristics of Ultrasonic Pulse-Echo Testing Instruments and Systems without theUse of Electronic Measurement Instruments2.2 Other Documents:ANSI/ASME B46.1 Surface Texture (Surface Roughness, Waviness and Lay)Recommended Practice No. SNT-TC-1A Personnel Qualification and Certific
10、ation in Nondestructive Testing33. Personnel Requirements3.1 Personnel performing ultrasonic examinations to this practice shall be qualified and certified in accordance with a writtenprocedure conforming to Recommended Practice No. SNT-TC-1A or other national standard acceptable to both the purchas
11、er andthe supplier.1 This practice is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloysand is the direct responsibility of Subcommittee A01.06 onSteel Forgings and Billets.Current edition approved March 1, 2012May 1, 2013. Published March 2012June 2013. Origin
12、ally approved in 1965. Last previous edition approved in 20062012 asA531/A531M 91A531/A531M 12. (2006). DOI: 10.1520/A0531_A0531M-12.10.1520/A0531_A0531M-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of AST
13、M Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from theAmerican Society for Nondestructive Testing, 914 ChicagoAve., Evanston, IL60202.Testing (ASNT), P.O. Box 28518, 1711Arlingate Ln., Columbus,OH 43228-0518, http:/www.asnt.org.This docum
14、ent is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as a
15、ppropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United
16、States14. Ordering Information4.1 When this practice is to be applied to an inquiry, contract, or order, the purchaser shall so state and shall also furnish thefollowing information:4.1.1 The method or combination of methods to be used for inspection.4.1.2 The frequency to be used for conducting eac
17、h inspection.4.1.3 Report requirements including C-scan plot, if applicable.4.1.4 Supplementary requirements, if any.5. General Requirements5.1 As far as possible the entire volume of the retaining rings shall be subject to ultrasonic inspection. Circumferential and axialfaces shall be machined flat
18、 and parallel to one another.5.2 The ultrasonic inspection shall be performed after final processing and heat treatment for properties, unless otherwisespecified in the order or contract.5.3 Rings may be tested either stationary (contact) or while rotating (immersion). If not specified by the purcha
19、ser, acombination of methods may be used at the manufacturers option. Scanning speed shall not exceed 6 in./s 15 cm/s, unlessautomatic recording (C-scan) equipment is employed.5.4 To ensure complete coverage (during contact testing), the search unit shall be indexed no more than 75 % of the transduc
20、erwidth with each pass of the search unit. During immersion testing establish a transducer index adjustment which will ensurecomplete coverage with sufficient overlap.5.5 During the testing, a combination of methods and frequencies of 1 MHz, 2 MHz, 214 MHz, and 5 MHz may be used foraccurately locati
21、ng, determining orientation, and defining specific discontinuities detected during overall scanning.5.6 For reporting purpose, location of indications shall be circumferentially defined by clock position. The test notch or a similarlocator, such as a reference line bisecting the serial number, shall
22、 be used to define and identify the 12 oclock position.6. Apparatus6.1 Electronic ApparatusA pulse-echo instrument permitting inspection frequencies of 1, 2.25, and at least 1 to 5 MHz isrequired. The accuracy of discontinuity amplitude analysis using this practice involves a knowledge of the true o
23、perating frequencyof the complete inspection system. One of the best ways to obtain the desired accuracy is by use of a tuned pulser and narrow bandamplifier of known frequency response, with either a broadband transducer, or a narrow-band tuned transducer of known andmatching frequency.6.1.1 Appara
24、tus Qualification and CalibrationBasic qualification of the ultrasonic test instrument shall be performed atintervals not to exceed 12 months or whenever maintenance is performed that affects the equipment function. The date of the lastcalibration and the date of the next required calibration shall
25、be displayed on the test equipment.6.1.2 The horizontal linearity shall be checked on a distance calibration bar using the multiple order technique (see PracticeE317). The horizontal linearity shall be 62 % of the metal path.6.1.3 The accuracy of the linearity shall be checked by ultrasonically veri
26、fying the thickness of the component in at least onelocation beyond the near field of the transducer. If necessary, minor adjustments for differences in the ultrasonic velocities betweenthe calibration bar and the forging shall then be made.6.1.4 When the immersion method of inspection is employed,
27、suitable equipment must be available so that the retaining ringscan be immersed in a liquid coupling agent or can be subject to inspection by the use of a column or stream of the couplant throughan appropriate container attached to the part or transducer. Equipment must also include fixturing for sm
28、ooth mechanical rotationof the part or the transducer during scanning.6.2 AmplifierThe amplifier and display shall provide linear response within 62 %, up to 100 % of full screen height.6.2.1 Amplifier CalibrationAn amplifier vertical linearity check shall be made prior to performing the test by obs
29、erving amultiple order pattern from a calibration block using a 2 or 2.25 MHz transducer (see Practice E317). The first back reflection shallbe set at 100 % of full screen height. The higher order back reflections, 10 % and higher in amplitude, shall also be positionedon the screen and their amplitu
30、des noted. The first back reflection shall be reduced to 50 % and then 25 % of full screen height.The amplitudes of the higher order back reflections shall be noted at each step. The vertical linearity will be considered acceptableif the signal heights of the higher order reflections decrease in pro
31、portion to the decrease set for the first back reflection. Themaximum acceptable error for the decrease of the higher order reflections is the greater of 65 % of the expected back reflectionheight or 62 % of full screen height.6.3 Signal AttenuatorThe instrument shall contain a calibrated gain contr
32、ol or signal attenuator that meets the requirementsof Practice E317 (in each case, accurate within 65 %) that will allow indications beyond the linear range of the instrument to bemeasured. It is recommended that these controls permit signal adjustments up to 25 to 1 (28 dB).6.4 Search Units:A531/A5
33、31M 1326.4.1 Contact Method:6.4.1.1 A 2.25 2.25, 2.0 or 1.0-MHz, 45 angle beam shear wave search unit shall be employed for shear wave testing (2.25(2.0 or 2.25 MHz shall be used unless acoustic attenuation of the material is such that 1 MHz must be employed to obtain adequatepenetration of the ring
34、 section). Adequate penetration is the ability to clearly resolve the calibration notch above resultant noiselevel.6.4.1.2 A5, 2.25, 2.0 or 1-MHz, 34 to 118-in. 19.020 to 28.6-mm30-mm diameter, longitudinal wave transducer shall be usedfor performing the longitudinal wave test.6.4.1.3 Acrylic resin
35、shoes ground to the curvature of the retaining ring may be used to maintain the optimum contact anglebetween the transducer and outside diameter of the ring.6.4.1.4 When agreed upon between the purchaser and supplier, alternative test frequencies may be used to perform the requiredtests.6.4.2 Immers
36、ion Method:6.4.2.1 A 5, 2.25, 2.0 or 1-MHz transducer, 34 to 1 in. 19.020 to 25.430 mm in diameter, suitable for water immersion, shallbe used for performing the required test.6.4.2.2 The manipulator (holder) for the search tube or transducer, or both, shall provide for angular manipulation of thetr
37、ansducer for optimum response from the internal discontinuities. The tolerance or play present in the manipulation and in thetraversing unit should not be excessive so as to prevent ultrasonic examination at the required sensitivity level.6.4.2.3 When agreed upon between the purchaser and supplier,
38、alternative test frequencies may be used to perform the requiredtests.6.4.2.4 Accessory EquipmentCoaxial cables and search tubes used in conjunction with the electronic apparatus capable ofconducting the electrical pulses while immersed in a liquid, and collimators for shaping the sound beam may be
39、used.6.5 Recording instruments or alarm systems, or both, may be used, provided sufficient range and sensitivity are available toproperly monitor the test.7. Preparation of the Forging for Ultrasonic Examination7.1 Surface roughness on the outside and inside diameter and radical face surfaces of the
40、 ring shall not exceed an Ra of 125in. 3.18 m (Ra is defined in ANSI/ASME B46.1), and waviness shall not exceed 0.001 in. 0.02 mm measured in both theaxial and circumferential directions. The radical faces of the ring shall be sufficiently perpendicular to the axis of the forging topermit axial test
41、s.7.2 All surfaces of the ring to be examined shall be free of extraneous material such as surface tears, loose scale, machiningor grinding particles, paint, and other foreign matter.8. Ultrasonic Couplants8.1 For contact testing, a suitable couplant, such as clean SAE 20 motor oil, shall be used to
42、 couple the transducer to testsurfaces.8.2 For immersion testing, a liquid such as water, oil, glycerin, etc., capable of conducting ultrasonic vibrations from thetransducer to the material being tested shall be used. Rust inhibitors, softeners, and wetting agents may be added to the couplant.The co
43、uplant liquid with all additives should not be detrimental to the surface condition of the test specimen or the container, andit should wet the surface of the material to provide an intimate contact. Couplant may be heated to a comfortable workingtemperature and must be free of air bubbles.9. Method
44、 for Shear Wave Testing9.1 Calibration Reference:9.1.1 Place a calibration V-shaped notch, with an included angle of 60 to 90 and 14 in. 6.35 mm long, in the outside diametersurface of the ring at a sufficient distance from the end of the ring to eliminate side wall interference. Determine the locat
45、ion ofthe notch by scanning the ring at a sensitivity high enough to show the material structure and with the shear wave beam directedcircumferentially. Using this procedure, then locate the notch in an area representative of the ring material.9.1.2 Place the notch axially in the ring to a depth of
46、1 % of the wall thickness or 0.020 in. 0.51 mm, whichever is greater.Make the depth measurement after removal of the upset material adjacent to the notch.9.1.3 For the inspection of finish machined rings, an outside reference block of the same alloy, wall thickness, and curvatureas the ring being te
47、sted may be used. The block must be at least 4 in. 10 cm wide and long enough to permit three bounces fromthe reference notch.9.1.4 For axial shear wave examination by the immersion method, place a circumferentially oriented notch into the outsidediameter surface of the ring at a sufficient distance
48、 from the end of the ring so that it can be clearly resolved from the outsidediameter corner reflection. Dimensions of notch shall be the same as described in 9.1.1.9.2 Contact Method for Equipment Calibration:A531/A531M 1339.2.1 Connect the 2.25-MHz 2.25-MHz, 2.0-MHz or 1-MHz angle beam search unit
49、 to the test instrument and place it directlyover the calibration notch with the crystal directed circumferentially. Move the search unit circumferentially, directing the soundbeam toward the notch until an indication from the notch appears. Continue to move the search unit in the same direction untila maximized second bounce indication appears.9.2.2 Adjust the sweep length so that the first and second bound indications from the notch are about 112 in. 38 mm apart.Mark and designate the first and second bounce positions on the sweep li
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