ASTM_G_209_-_14.pdf

Designation:G20914Standard Practice forDetecting mu-phase in Wrought Nickel-Rich,Chromium,Molybdenum-Bearing Alloys1This standard is issued under the fixed designation G209;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1This practice incorporates etching and metallographicexaminationofWroughtNickel-Rich,Chromium,Molybdenum-Bearing Alloys such as,but not limited to,UNSN06686 and UNS N10276.1.2Microstructures have a strong influence on propertiesand successful application of metals and alloys.The presenceof mu-phase in the microstructure may significantly reduce thecorrosion resistance of Wrought Nickel-Rich,Chromium,andMolybdenum-Bearing Alloys.1.3 This practice may be used to determine the presence ofmu-phaseinWroughtNickel-Rich,Chromium,andMolybdenum-Bearing Alloys through comparison of micro-structure observed for etched metallographic specimens to aglossary of photomicrographs displaying the presence andabsence of mu-phase in the microstructure.1.4 The values stated in SI units are to be regarded as thestandard.Other units are given in parentheses for informationonly.1.5 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:2D1193 Specification for Reagent WaterE3 Guide for Preparation of Metallographic SpecimensE7 Terminology Relating to MetallographyE1245 Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic ImageAnalysisE1268 Practice for Assessing the Degree of Banding orOrientation of MicrostructuresG193 Terminology and Acronyms Relating to Corrosion3.Terminology3.1 Definitions:3.1.1 The terminology used herein,if not specifically de-fined otherwise,shall be in accordance with TerminologyG193.Definitions provided herein and not given in Terminol-ogy G193 are limited only to this practice.3.1.2 For metallographic definitions used in this practice,refer to Terminology E7.3.1.3 For evaluation of inclusions,secondary phases andbanding,if desired,refer to Practices E1245 and E1268.3.2 Definitions of Terms Specific to This Standard:3.2.1 mu-phase(),nrhombohedral phase which mayoccur in Nickel-Rich,Chromium,Molybdenum-Bearing Al-loys and may occur as coarse,irregular platelets,which form athigh temperature.4.Significance and Use4.1 These test methods describe laboratory tests to deter-mine the presence of mu-phase in Wrought Nickel-Rich,Chromium,and Molybdenum-Bearing Alloys through com-parison of microstructure observed for etched metallographicspecimens to a glossary of photomicrographs displaying thepresence and absence of mu-phase in the microstructure.Thepresence of mu-phase in the microstructure may significantlyreduce the corrosion resistance,strength,toughness and duc-tility of Wrought Nickel-Rich,Chromium,and Molybdenum-Bearing Alloys.5.Sample Preparation and Etching35.1 Sectioning:5.1.1 The selection of test specimens for metallographicexamination is extremely important because,if their interpre-tation is to be of value,the specimens must be representative of1This test method is under the jurisdiction of ASTM Committee G01 onCorrosion of Metals and is the direct responsibility of Subcommittee G01.05 onLaboratory Corrosion Tests.Current edition approved Nov.1,2014.Published November 2014.Originallyapproved in 2012.Last previous edition approved in 2013 as G20913.DOI:10.1520/G0209-14.2For 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.3Manning,Paul E.,Ph.D.,Metallographic Preparation of 686 EtchingSpecimens,Haynes International,Inc.,Kokomo,IN,2011.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 the material that is being studied and shall be per location E(longitudinal section perpendicular to rolled surface)for plateand sheet and per location G(radial longitudinal section)forrod and bar per Fig.1(Guide E3).The intent or purpose of themetallographic examination will usually dictate the location ofthe specimens to be studied.For rod and bar test specimensspecifically,samples are taken from location G as seen in Fig.1.Triplicate test specimens shall be evaluated for determina-tion of the presence of mu-phase.5.1.2 Cut the specimen to a convenient size using any ofvarious types of silicon carbide,diamond,boron carbide orother carbide cutoff blades.Deformation damage can beminimized by using thin cutoff wheel