ASTM_B_858_-_06_2012.pdf

Designation:B85806(Reapproved 2012)Standard Test Method forAmmonia Vapor Test for Determining Susceptibility toStress Corrosion Cracking in Copper Alloys1This standard is issued under the fixed designation B858;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.Scope1.1 This test method describes a procedure to determine thepresence of residual stresses in wrought copper alloy productsthat may lead to stress corrosion cracking.An ammonia vaporatmosphere is used as an accelerated test.1.2 This test method is only suitable for products fabricatedfrom copper alloys that are known to be susceptible to stresscorrosion cracking in ammonia vapor atmospheres.It is in-tended to create an environmental condition of reproducibleseverity.NOTE1It is well known that the critical step in the crackingmechanism is the development of an environment in the condensate filmthat occurs on the surface of the test specimen,and is rich in coppercomplex ions.1.3 The severity of this test method depends upon the pH ofthe corrosive solution.In Annex A1 are given four differentatmospheres to which the product may be exposed,and theappropriate pH of the solution to be used for the test,depending on the risk level associated with the intendedapplication.1.3.1 The appropriate pH value for the test shall be specifiedin the product specification,or as per established agreementbetween the supplier and purchaser,with respect to the alloyand its intended application.1.4 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in thisstandard.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:2B154 Test Method for Mercurous Nitrate Test for CopperAlloysB846 Terminology for Copper and Copper AlloysD1193 Specification for Reagent Water3.Terminology3.1 For definitions of terms related to copper and copperalloys,refer to Terminology B846.3.2 Definitions:3.2.1 applied stress,nstress in a body as a result ofapplication of an external load.4.Summary of Test Method4.1 The prepared test specimen is placed in a closedcontainer and exposed to ammonia vapor with a specific pH atambient temperature for 24 h.Upon removal from the testatmosphere,the test specimen is examined for the presence ofcracks.5.Significance and Use5.1 This test method is an accelerated test to determine if acopper alloy product will be susceptible to stress-corrosioncracking when exposed to a particular atmospheric conditionduring service with the appropriate risk levelsee Annex A1.5.1.1 This test method is generally intended to determine ifa copper alloy product will crack because of internal stresseswhen subjected to the test,and is not intended for testingassemblies under applied stress.If used for this purpose,it shallbe for information only and not a cause for rejection of theassembly,its component parts,or the original mill product.6.Apparatus6.1 pH meter.6.2 Closed vessel,such as a desiccator.1This test method is under the jurisdiction of ASTM Committee B05 on Copperand Copper Alloys and is the direct responsibility of Subcommittee B05.06 onMethods of Test.Current edition approved April 1,2012.Published August 2012.Originallyapproved in 1995.Last previous edition approved in 2006 as B858 06.DOI:10.1520/B0858-06R12.2For 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 States1 6.3 Equipment for examining test pieces at 10 to 15magnification.7.Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.3Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water as definedby Type IV or better,of Specification D1193.7.3 Ammonium Chloride Solution(4N)Dissolve 107 g ofammonium chloride(NH4Cl)in water and dilute to 500 mL.Store the solution i