ASTM_A_923_-_14.pdf

Designation:A92314Standard Test Methods forDetecting Detrimental Intermetallic Phase in DuplexAustenitic/Ferritic Stainless Steels1This standard is issued under the fixed designation A923;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.Scope*1.1 The purpose of these test methods is to allow detectionof the presence of intermetallic phases in duplex stainless steelsto the extent that toughness or corrosion resistance is affectedsignificantly.These test methods will not necessarily detectlosses of toughness or corrosion resistance attributable to othercauses.1.2 Duplex(austenitic-ferritic)stainless steels are suscep-tible to the formation of intermetallic compounds duringexposures in the temperature range from approximately 600 to1750F(320 to 955C).The speed of these precipitationreactions is a function of composition and thermal or thermo-mechanical history of each individual piece.The presence ofthese phases is detrimental to toughness and corrosion resis-tance.1.3 Correct heat treatment of duplex stainless steels caneliminate these detrimental phases.Rapid cooling of theproduct provides the maximum resistance to formation ofdetrimental phases by subsequent thermal exposures.1.4 Compliance with the chemical and mechanical require-ments for the applicable product specification does not neces-sarily indicate the absence of detrimental phases in the product.1.5 These test methods include the following:1.5.1 Test Method ASodium Hydroxide Etch Test forClassification of Etch Structures of Duplex Stainless Steels(Sections 3 7).1.5.2 Test Method BCharpy Impact Test for Classificationof Structures of Duplex Stainless Steels(Sections 8 13).1.5.3 Test Method CFerric Chloride Corrosion Test forClassification of Structures of Duplex Stainless Steels(Sec-tions 14 20).1.6 The presence of detrimental intermetallic phases isreadily detected in all three tests,provided that a sample ofappropriate location and orientation is selected.Because theoccurrence of intermetallic phases is a function of temperatureand cooling rate,it is essential that the tests be applied to theregion of the material experiencing the conditions most likelyto promote the formation of an intermetallic phase.In the caseof common heat treatment,this region will be that whichcooled most slowly.Except for rapidly cooled material,it maybe necessary to sample from a location determined to be themost slowly cooled for the material piece to be characterized.1.7 The tests do not determine the precise nature of thedetrimental phase but rather the presence or absence of anintermetallic phase to the extent that it is detrimental to thetoughness and corrosion resistance of the material.1.8 Examples of the correlation of thermal exposures,theoccurrence of intermetallic phases,and the degradation oftoughness and corrosion resistance are given in Appendix X1and Appendix X2.1.9 The values stated in either inch-pound or SI units are tobe regarded as the standard.The values given in parenthesesare for information only.1.10 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:2A370 Test Methods and Definitions for Mechanical Testingof Steel Products1These test methods are under the jurisdiction of ASTM Committee A01 onSteel,Stainless Steel and Related Alloysand are the direct responsibility ofSubcommittee A01.14 on Methods of Corrosion Testing.Current edition approved March 1,2014.Published March 2014.Originallyapproved in 1994.Last previous edition approved in 2008 as A923 08.DOI:10.1520/A0923-14.2For 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.*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 States1Copyright by ASTM Intl(all rights reserved);G48 Test Methods for Pitting and Crevice Corrosion Resis-tance of Stainless Steels and Related Alloys by Use ofFerric Chloride SolutionTEST METHOD ASODIUM HYDROXIDE ETCHTEST FOR CLASSIFICATION OF ETCHSTRUCTURES OF DUPLEX STAINLESS STEELS3.Scope3.1 The sodium hydroxide etch test may be used for theacceptance of material but not for rejection.This test methodmay be used with other evaluation tests to provide a rapidmethod for identifying those specimens that are free ofdetrimental intermetallic phases as measured in these othertests.3