ASTM_A_1084_-_15a.pdf

Designation:A108415aStandard Test Method forDetecting Detrimental Phases in Lean Duplex Austenitic/Ferritic Stainless Steels1This standard is issued under the fixed designation A1084;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 this test method is to allow detection ofthe presence of detrimental chromium-containing phases inselected lean duplex stainless steels to the extent that toughnessor corrosion resistance is affected significantly.Such phasescan form during manufacture and fabrication of lean duplexproducts.This test method does not necessarily detect losses oftoughness nor corrosion resistance attributable to other causes,nor will it identify the exact type of detrimental phases thatcaused any loss of toughness or corrosion resistance.The testresult is a simple pass/fail statement.1.2 Lean duplex(austenitic-ferritic)stainless steels are typi-cally duplex stainless steels composed of 30 to 70%ferritecontent with a typical alloy composition having Cr 17%andMo 1%and with additions of Nickel,Manganese,Nitrogenand controlled low carbon content as well as other alloyingelements.This standard test method applies only to thosealloys listed in Table 1.Similar test methods for some higheralloyed duplex stainless steels are described in Test MethodsA923,but the procedures described in this standard differsignificantly for all three methods from the ones described inTest Methods A923.1.3 Lean duplex stainless steels are susceptible to theformation of detrimental chromium-containing compoundssuch as nitrides and carbides and other undesirable phases.Typically this occurs during exposures in the temperature rangefrom approximately 300 to 955C(570 to 1750F)with amaximum susceptibility in the temperature range around 650 to750C(1200 to 1385F).The speed of these precipitationreactions is a function of composition and the thermal orthermo-mechanical history of each individual piece.The pres-ence of an amount of these phases can be detrimental totoughness and corrosion resistance.1.4 Because of the low molybdenum content,lean duplexstainless steels only exhibit a minor susceptibility to sigma orother types of molybdenum containing intermetallic phases.Heat treatment,that could lead to formation of small amountsof molybdenum containing intermetallics,would result in alarge amount of precipitation of detrimental nitrides orcarbides,long before any signs of sigma and similar phaseswould be observed.1.5 Correct heat treatment of lean duplex stainless steels caneliminate or reduce the amount and alter the characteristics ofthese detrimental phases as well as minimizing Cr-depletion inthe matrix phase in the immediate vicinity of these phases.Adequately rapid cooling of the product from a suitableannealing temperature provides the maximum resistance toformation of detrimental phases by subsequent thermal expo-sures.For details of the proper annealing temperature recom-mendations for the alloy and product in question,the user isreferred to the relevant applicableASTM product specification.1.6 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.1.7 These test methods include the following:1.7.1 Test Method AEtch Method for detecting the pres-ence of potentially detrimental phases in Lean Duplex StainlessSteels1.7.2 Test Method BCharpy V-notch Impact Test fordetermining the presence of detrimental phases in Lean DuplexStainless Steels.1.7.3 Test Method CInhibited Ferric Chloride CorrosionTest for determining the presence of detrimental phases in LeanDuplex Stainless Steels.1.7.4 Examples of the correlation of thermal exposures,theoccurrence of detrimental phases,and the degradation oftoughness and corrosion resistance are given in Appendix X2,Appendix X3,and the References.1.8 Guidelines for the required data needed for subcommit-tee A01.14 to consider listing a lean duplex stainless steel inthis standard test method are given in Annex A1.1.9 The values stated in SI units are to be regarded asstandard.The values given in parentheses are mathematicalconversions to other units that are provided for informationonly and are not considered standard.1This test method is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.14 on Methods of Corrosion Testing.Current edition approved Sept.1,2015.Published September 2015.Originallyapproved in 2013.Last previous edition approved in 2015 as A1084 15.DOI:10.1520/A1084 15A.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Consho