ASTM_E_2985_-_E_2985M_-_14.pdf

Designation:E2985/E2985M14Standard Practice forDetermination of Metal Purity Based on Elastic ConstantMeasurements Derived from Resonant UltrasoundSpectroscopy1This standard is issued under the fixed designation E2985/E2985M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,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.Scope1.1 This practice is intended for use with resonant ultra-sound spectrometers capable of exciting,measuring,recordingand analyzing multiple whole body mechanical vibrationresonant frequencies within parts exhibiting acoustical ringingin the acoustic or ultrasonic,or both,resonant frequencyranges.1.2 This practice uses Resonant Ultrasound Spectroscopy(RUS)to distinguish conforming parts,as determined fromqualified training sets,from those containing significantanomalies in their elastic properties.1.3 The basic functions of a RUS monitoring system are todetect and classify resonance phenomena.Solid structureresonances are governed by the parts dimensions,density andelastic properties.When a material substitution occurs in aprecious metal,the chosen metals have almost identical den-sities and unchanged dimensions,leaving only the elasticproperties to affect the resonances.1.4 This practice can be used to replace destructivemethods,which damage the test object through drilling ormelting,or both.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.6 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 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E543 Specification for Agencies Performing NondestructiveTestingE1316 Terminology for Nondestructive ExaminationsE2001 Guide for Resonant Ultrasound Spectroscopy forDefect Detection in Both Metallic and Non-metallic Parts2.2 Other Referenced DocumentsANSI/ASNT CP-189 Standard for Qualification and Certifi-cation of Nondestructive Testing Personnel3NAS-410 NDT Certification4SNT-TC-1A Personnel Qualification and Certification inNondestructive Testing53.Terminology3.1 DefinitionsThe definitions of terms relating to conven-tional ultrasonic examination can be found in TerminologyE1316.3.2 Resonant ultrasound spectroscopy(RUS)Basic RUSwas originally applied in fundamental research applications inphysics and materials science.A few other recognizable namesinclude acoustic resonance spectroscopy,acoustic resonantinspection,and resonant inspection.Guide E2001 documentsRUS extensively.A nondestructive examination method whichemploys the measurement and analysis of acoustic or ultra-sound resonance patterns,or both,for the identification ofacceptable variations in the physical characteristics of test partsin production environments.In this procedure an isolated,rigidpart is caused to resonate.Certain resonances are measured andcompared to a previously defined acceptable pattern combina-tion of resonances.Based on this comparison the part is judged1This test method is under the jurisdiction of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.06 onUltrasonic Method.Current edition approved Oct.1,2014.Published October 2014.DOI:10.1520/E2985_E2985M-142For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.4Available from Aerospace Industries Association of America,Inc.(AIA),1000Wilson Blvd.,Suite 1700,Arlington,VA22209-3928,http:/www.aia-aerospace.org.5Available fromAmerican Society for Nondestructive Testing(ASNT),P.O.Box28518,1711 Arlingate Ln.,Columbus,OH 43228-0518,http:/www.asnt.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 to be acceptable or,if it does not conform to the establishedpattern,to be unacceptable.4.Summary of Practice4.1 Reports indicating that gold bullion is being physicallyhollowed and replaced with similar density metals,such astungsten,are surfacing.While not a huge concern for theoriginal manufacturer,the secondary exchange market canexperience disruption if the integrity of the asset comes intoquestion.Verifying the sample purity is critical and must beperformed q