ASTM_G_168_-_00_2013.pdf

Designation:G16800(Reapproved 2013)Standard Practice forMaking and Using Precracked Double Beam StressCorrosion Specimens1This standard is issued under the fixed designation G168;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 practice covers procedures for fabricating,preparing,and using precracked double beam stress corrosiontest specimens.This specimen configuration was formerlydesignated the double cantilever beam(DCB)specimen.Guidelines are given for methods of exposure and inspection.1.2 The precracked double beam specimen,as described inthis practice,is applicable for evaluation of a wide variety ofmetals exposed to corrosive environments.It is particularlysuited to evaluation of products having a highly directionalgrain structure,such as rolled plate,forgings,and extrusions,when stressed in the short transverse direction.1.3 The precracked double beam specimen may be stressedin constant displacement by bolt or wedge loading or inconstant load by use of proof rings or dead weight loading.Theprecracked double beam specimen is amenable to exposure toaqueous or other liquid solutions by specimen immersion or byperiodic dropwise addition of solution to the crack tip,orexposure to the atmosphere.1.4 This practice is concerned only with precracked doublebeam specimen and not with the detailed environmentalaspects of stress corrosion testing,which are covered inPractices G35,G36,G37,G41,G44,and G50.1.5 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 WaterE399 Test Method for Linear-Elastic Plane-Strain FractureToughness KIcof Metallic MaterialsE1823 Terminology Relating to Fatigue and Fracture TestingG15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)3G35 Practice for Determining the Susceptibility of StainlessSteels and Related Nickel-Chromium-Iron Alloys toStress-Corrosion Cracking in Polythionic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 AlloysG41 Practice for Determining Cracking Susceptibility ofMetals Exposed Under Stress to a Hot Salt EnvironmentG44 Practice for Exposure of Metals andAlloys byAlternateImmersion in Neutral 3.5%Sodium Chloride SolutionG49 Practice for Preparation and Use of Direct TensionStress-Corrosion Test SpecimensG50 Practice for Conducting Atmospheric Corrosion Testson Metals3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 stress corrosion cracking(SCC)threshold stressintensity,KIsccthe stress intensity level below which stresscorrosion cracking does not occur for a specific combination ofmaterial and environment when plane strain conditions aresatisfied.3.1.1.1 DiscussionTerms relative to this subject mattercan be found in Terminologies G15 and E1823.4.Summary of Practice4.1 This practice covers the preparation and testing ofprecracked double beam specimens for investigating the resis-tance to SCC(see Terminology G15)of metallic materials invarious product forms.Precracking by fatigue loading and bymechanical overload are described.Procedures for stressing1This 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 May 1,2013.Published July 2013.Originally approvedin 2000.Last previous edition approved in 2006 as G168 00(2006).DOI:10.1520/G0168-00R13.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 specimens in constant displacement with loading bolts aredescribed,and expressions are given for specimen stressintensity and crack mouth opening displacement.Guidance isgiven for methods of exposure and inspection of precrackeddouble beam specimens.5.Significance and Use5.1 Precracked specimens offer the opportunity to use theprinciples of linear elastic fracture mechanics(1)4to evaluateresistance to stress corrosion cracking in the presence of apre-existing crack.T