ASTM_G_49_-_85_2011.pdf

Designation:G4985(Reapproved 2011)Standard Practice forPreparation and Use of Direct Tension Stress-CorrosionTest Specimens1This standard is issued under the fixed designation G49;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers procedures for designing,prepar-ing,and using ASTM standard tension test specimens forinvestigating susceptibility to stress-corrosion cracking.Axi-ally loaded specimens may be stressed quantitatively withequipment for application of either a constant load,constantstrain,or with a continuously increasing strain.1.2 Tension test specimens are adaptable for testing a widevariety of product forms as well as parts joined by welding,riveting,or various other methods.1.3 The exposure of specimens in a corrosive environmentis treated only briefly because other standards are beingprepared to deal with this aspect.Meanwhile,the investigatoris referred to Practices G35,G36,G37,and G44,and toASTMSpecial Technical Publication 425(1).22.Referenced Documents2.1 ASTM Standards:3E8 Test Methods for Tension Testing of Metallic MaterialsG35 Practice for Determining the Susceptibility of StainlessSteels and Related Nickel-Chromium-Iron Alloys toStress-Corrosion Cracking in Polythionic AcidsG36 Practice for Evaluating Stress-Corrosion-Cracking Re-sistance of Metals and Alloys in a Boiling MagnesiumChloride SolutionG37 Practice for Use of Mattssons Solution of pH 7.2 toEvaluate the Stress-Corrosion Cracking Susceptibility ofCopper-Zinc AlloysG44 Practice for Exposure of Metals andAlloys byAlternateImmersion in Neutral 3.5%Sodium Chloride Solution3.Summary of Practice3.1 This practice covers the use of axially loaded,quantita-tively stressed ASTM standard tension test specimens forinvestigating the resistance to stress-corrosion cracking ofmetallic materials in all types of product forms.Considerationis given to important factors in the selection of appropriatespecimens,the design of loading equipment,and the effects ofthese factors on the state of stress in the specimen as corrosionoccurs.4.Significance and Use4.1 Axially loaded tension specimens provide one of themost versatile methods of performing a stress-corrosion testbecause of the flexibility permitted in the choice of type andsize of test specimen,stressing procedures,and range of stresslevels.4.2 The uniaxial stress system is simple;hence,this testmethod is often used for studies of stress-corrosion mecha-nisms.This type of test is amenable to the simultaneousexposure of unstressed specimens(no applied load)withstressed specimens and subsequent tension testing to distin-guish between the effects of true stress corrosion and mechani-cal overload(2).Additional considerations in regard to thesignificance of the test results and their interpretation are givenin Sections 6 and 10.4.3 Wide variations in test results may be obtained for agiven material and specimen orientation with different speci-men sizes and stressing procedures.This consideration issignificant especially in the standardization of a test procedurefor interlaboratory comparisons or quality control.5.Test Specimens5.1 Whenever possible,tension test specimens used inevaluating susceptibility to stress-corrosion cracking shouldconform to the dimensions of standard tension test specimensspecified in Test Methods E8,which contain details forspecimens machined from various product forms.5.2 A wide range of sizes for tension test specimens ispossible,depending primarily upon the dimensions of theproduct to be tested.Because the stress-corrosion test resultscan be markedly influenced by the cross section of the test1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of Subcommittee G01.06 on Environmen-tally Assisted Cracking.Current edition approved March 1,2011.Published April 2011.Originallyapproved in 1976.Last previous edition approved in 2005 as G4985(2005).DOI:10.1520/G0049-85R11.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 specimen,this factor should be given careful considerationwith regard to the object of the investigation.Although largerspecimens may be more representative of most actual struc-tures,they often cannot be machined from product forms to beevaluated;and they present more difficulties in stressing andhandling in the laboratory.Also,larger specimens