1、Designation: A 531/A 531M 91 (Reapproved 2006)Standard Practice forUltrasonic Examination of Turbine-Generator Steel RetainingRings1This standard is issued under the fixed designationA 531/A 531M; the number immediately following the designation indicates the yearof original adoption or, in the case
2、 of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the procedures to be followed whenperforming ultrasonic shear and long
3、itudinal wave tests onturbine-generator retaining rings with an inside diameter towall thickness ratio equal to or greater than 5:1 and with wallthicknesses from 1 to 4 in. (25 to 102 mm).1.2 Although this practice describes methods of ultrasoni-cally testing retaining rings by either the contact or
4、 immersionmethod, it shall not restrict the use of improved inspectionmethods as they are developed. It is recognized that techniquesfor examination and evaluation may be chosen in order toenhance or improve the results or to accommodate variations inprocedures, equipment, or capabilities. Consideri
5、ng these char-acteristics, forgings may be inspected by a combination of boththe contact and the immersion methods, as mutually agreedupon between the manufacturer and the purchaser.1.3 This practice and the applicable material specificationsare expressed in both inch-pound units and SI units. Howev
6、er,unless the order specifies the applicable “M” specificationdesignation SI units, the material shall be furnished to inch-pound units.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to es
7、tablish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 127 Practice for Fabricating and Checking AluminumAlloy Ultrasonic Standard Reference Blocks2.2 Other Document:Recommended Practice fo
8、r Nondestructive Personnel Quali-fication and Certification SNT-TC-1A, SupplementC-Ultrasonic Testing33. Personnel Requirements3.1 The manufacturer shall be responsible for assigningqualified personnel to perform ultrasonic examination in con-formance with the requirements of this practice.3.2 Perso
9、nnel performing ultrasonic examinations in accor-dance with this practice shall be familiar with the following:3.2.1 Ultrasonic terminology,3.2.2 Instrument calibration,3.2.3 Effect of transducer material, size, frequency, andmode on test results,3.2.4 Effect of material structure (grain size, clean
10、liness,etc.) on test results,3.2.5 Effect of test distance on test results,3.2.6 Effect of nonlinearity on test results,3.2.7 Effect of thickness and orientation of discontinuitieson test results, and3.2.8 Effect of surface roughness on test results.3.3 A qualification record (see Note 1) of personn
11、el consid-ered suitable by the manufacturer to perform examination inaccordance with this practice shall be available upon request.NOTE 1SNT-TC-1 A, Ultrasonic Testing Method, provides a recom-mended procedure for qualifying personnel. Other personnel qualificationrequirement documents may be used w
12、hen agreed upon between thepurchaser and supplier.4. Ordering Information4.1 When this practice is to be applied to an inquiry,contract, or order, the purchaser shall so state and shall alsofurnish the following information:4.1.1 The method or combination of methods to be used forinspection.4.1.2 Th
13、e frequency to be used for conducting each inspec-tion.4.1.3 Report requirements including C-scan plot, if appli-cable.1This practice is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.06 on Steel Forgings a
14、nd Billets.Current edition approved March 1, 2006. Published April 2006. Originallyapproved in 1965. Last previous edition approved in 2001 as A 531/A 531M 91(2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Bo
15、ok of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from the American Society for Nondestructive Testing, 914 ChicagoAve., Evanston, IL 60202.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-
16、2959, United States.5. General Requirements5.1 As far as possible the entire volume of the retainingrings shall be subject to ultrasonic inspection. Circumferentialand axial faces shall be machined flat and parallel to oneanother.5.2 The ultrasonic inspection shall be performed after finalprocessing
17、 and heat treatment for properties, unless otherwisespecified in the order or contract.5.3 Rings may be tested either stationary (contact) or whilerotating (immersion). If not specified by the purchaser, acombination of methods may be used at the manufacturersoption. Scanning speed shall not exceed
18、6 in./s (152 mm/s),unless automatic recording (C-scan) equipment is employed.5.4 To ensure complete coverage (during contact testing),the search unit shall be indexed approximately 75 % of thetransducer width with each pass of the search unit. Duringimmersion testing establish a transducer index adj
19、ustmentwhich will ensure complete coverage with sufficient overlap.5.5 During the testing, a combination of methods andfrequencies of 1 MHz, 214 MHz, and 5 MHz may be used foraccurately locating, determining orientation, and defining spe-cific discontinuities detected during overall scanning.5.6 For
20、 reporting purpose, location of indications shall becircumferentially defined by clock position. The test notch or asimilar locator, such as a reference line bisecting the serialnumber, shall be used to define and identify the 12 oclockposition.6. Apparatus6.1 Ultrasonic, Pulsed, Reflection Type of
21、Instrument, shallbe used for the examination. The system shall have a minimumcapability for examining at frequencies from 1 to 5 MHz.6.1.1 The amplifier and the cathode ray tube shall providelinear response (within 5 %) for at least 75 % of the screenheight (sweep line to top of screen).6.1.2 The in
22、strument shall contain a calibrated gain controlor signal attenuator (in each case, accurate within 65 %) thatwill allow indications beyond the linear range of the instrumentto be measured.6.1.3 When the immersion method of inspection is em-ployed, suitable equipment must be available so that theret
23、aining rings can be immersed in a liquid coupling agent orcan be subject to inspection by the use of a column or streamof the couplant through an appropriate container attached to thepart or transducer. Equipment must also include fixturing forsmooth mechanical rotation of the part or the transducer
24、 duringscanning.6.2 Search Units:6.2.1 Contact Method:6.2.1.1 A 2.25 or 1.0-MHz, 45 angle beam shear wavesearch unit shall be employed for shear wave testing (2.25MHz shall be used unless acoustic attenuation of the materialis such that 1 MHz must be employed to obtain adequatepenetration of the rin
25、g section). Adequate penetration is theability to clearly resolve the calibration notch above resultantnoise level.6.2.1.2 A5, 2.25, or 1-MHz,34 to 118-in. (19.0 to 28.6-mm)diameter, longitudinal wave transducer shall be used forperforming the longitudinal wave test.6.2.1.3 Acrylic resin shoes groun
26、d to the curvature of theretaining ring may be used to maintain the optimum contactangle between the transducer and outside diameter of the ring.6.2.1.4 When agreed upon between the purchaser and sup-plier, alternative test frequencies may be used to perform therequired tests.6.2.2 Immersion Method:
27、6.2.2.1 A 5, 2.25, or 1-MHz transducer,34 to 1 in. (19.0 to25.4 mm) in diameter, suitable for water immersion, shall beused for performing the required test.6.2.2.2 The manipulator (holder) for the search tube ortransducer, or both, shall provide for angular manipulation ofthe transducer for optimum
28、 response from the internal discon-tinuities. The tolerance or play present in the manipulation andin the traversing unit should not be excessive so as to preventultrasonic examination at the required sensitivity level.6.2.2.3 When agreed upon between the purchaser and sup-plier, alternative test fr
29、equencies may be used to perform therequired tests.6.2.2.4 Accessory EquipmentCoaxial cables and searchtubes used in conjunction with the electronic apparatus capableof conducting the electrical pulses while immersed in a liquid,and collimators for shaping the sound beam may be used.6.3 Recording in
30、struments or alarm systems, or both, maybe used, provided sufficient range and sensitivity are availableto properly monitor the test.7. Preparation of the Forging for Ultrasonic Examination7.1 Surface roughness on the outside and inside diameterand radical face surfaces of the ring shall not exceed
31、125 in.(3.18 m) and waviness shall not exceed 0.001 in. (0.02 mm)measured in both the axial and circumferential directions. Theradical faces of the ring shall be sufficiently perpendicular tothe axis of the forging to permit axial tests.7.2 All surfaces of the ring to be examined shall be free ofext
32、raneous material such as surface tears, loose scale, machin-ing or grinding particles, paint, and other foreign matter.8. Ultrasonic Couplants8.1 For contact testing, a suitable couplant, such as cleanSAE 20 motor oil, shall be used to couple the transducer to testsurfaces.8.2 For immersion testing,
33、 a liquid such as water, oil,glycerin, etc., capable of conducting ultrasonic vibrations fromthe transducer to the material being tested shall be used. Rustinhibitors, softeners, and wetting agents may be added to thecouplant. The couplant liquid with all additives should not bedetrimental to the su
34、rface condition of the test specimen or thecontainer, and it should wet the surface of the material toprovide an intimate contact. Couplant may be heated to acomfortable working temperature and must be free of airbubbles.9. Method for Shear Wave Testing9.1 Calibration Reference:A 531/A 531M 91 (2006
35、)29.1.1 Place a calibration V-shaped notch, with an includedangle of 60 to 90 and14 in. (6.35 mm) long, in the outsidediameter surface of the ring at a sufficient distance from the endof the ring to eliminate side wall interference. Determine thelocation of the notch by scanning the ring at a sensit
36、ivity highenough to show the material structure and with the shear wavebeam directed circumferentially. Using this procedure, thenlocate the notch in an area representative of the ring material.9.1.2 Place the notch axially in the ring to a depth of 1 % ofthe wall thickness or 0.020 in. (0.51 mm), w
37、hichever is greater.Make the depth measurement after removal of the upsetmaterial adjacent to the notch.9.1.3 For the inspection of finish machined rings, an outsidereference block of the same alloy, wall thickness, and curvatureas the ring being tested may be used. The block must be at least4 in. (
38、102 mm) wide and long enough to permit three bouncesfrom the reference notch.9.1.4 For axial shear wave examination by the immersionmethod, place a circumferentially oriented notch into theoutside diameter surface of the ring at a sufficient distance fromthe end of the ring so that it can be clearly
39、 resolved from theoutside diameter corner reflection. Dimensions of notch shallbe the same as described in 9.1.1.9.2 Contact Method for Equipment Calibration:9.2.1 Connect the 2.25-MHz or 1-MHz angle beam searchunit to the test instrument and place it directly over thecalibration notch with the crys
40、tal directed circumferentially.Move the search unit circumferentially, directing the soundbeam toward the notch until an indication from the notchappears. Continue to move the search unit in the same directionuntil a maximized second bounce indication appears.9.2.2 Adjust the sweep length so that th
41、e first and secondbound indications from the notch are about 112 in. (38 mm)apart. Mark and designate the first and second bounce positionson the sweep line.9.2.3 Adjust the gain until the first bounce indication has asweep-to-peak amplitude of 1.5 in. (38 mm). Mark the uppertip of this indication a
42、nd the point midway between the tip andthe sweep line. Check the notch in the reverse direction; if amarked difference in amplitude is found, make a new notch.9.2.4 In a similar manner, locate and mark the position ofthe tip and point midway between the tip and sweep line of thesecond bounce notch i
43、ndication. Draw a line connecting thetwo points designating the amplitudes of the first and secondnotch indications. Likewise, draw a line through the half-amplitude points. Refer to these lines as the amplitude andhalf-amplitude reference lines.9.3 Immersion Method for Equipment Calibration:9.3.1 C
44、ircumferential:9.3.1.1 With the transducer located perpendicular to theoutside diameter so as to obtain a 3 614-in. (76 6 6.35-mm)water path, adjust the sweep delay and sweep length to positionthe water steel interface reflection at the left of the screen, andthe first back reflection from the outsi
45、de diameter of the ringslightly to the left of center of the screen, so that at least twoangular passes through the ring will be visible on the screen.Position the transducer over the calibration reference andadjust the angle and horizontal position to maximize theindication from the reference notch
46、. Check the notch in thereverse direction; if a marked difference in amplitude is noted,make a new notch.9.3.1.2 Adjust the gain until the first bounce indication hasa sweep-to-peak amplitude of 1.5 in. (38 mm). Mark the uppertip of this indication and the point midway between the tip andthe sweep l
47、ine.9.3.1.3 In a similar manner, locate and mark the position ofthe tip and point midway between the tip and sweep line of thesecond bounce notch indication. Draw a line connecting thetwo points designating the amplitudes of the first and secondnotch indications. Likewise, draw a line through the ha
48、lf-amplitude points. Refer to these lines as the amplitude andhalf-amplitude reference lines.9.3.2 Axial:9.3.2.1 With the transducer located perpendicular to theoutside diameter so as to obtain a 3 614-in. (76 6 6.35-mm)water path as previously described in 9.3.1.1, position thetransducer over the c
49、ircumferential reference notch, and adjustthe angle and horizontal position to maximize the indicationfrom the reference notch while directing the ultrasonic beamtoward the nearest end face of the ring.9.3.2.2 Adjust the gain until the first bounce indication hasa sweep-to-peak amplitude of 1.5 in. (38 mm). Mark the uppertip of this indication and the point midway between the tip andthe sweep line.9.3.2.3 In a similar manner, locate and mark the position ofthe tip and point midway between the tip and sweep line of thesecond bounce notch indication. Draw a line connect
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