ASTM_G_35_-_98_2015.pdf

Designation:G3598(Reapproved 2015)Standard Practice forDetermining the Susceptibility of Stainless Steels andRelated Nickel-Chromium-Iron Alloys to Stress-CorrosionCracking in Polythionic Acids1This standard is issued under the fixed designation G35;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 preparing and con-ducting the polythionic acid test at room temperature,22 to25C(72 to 77F),to determine the relative susceptibility ofstainless steels or other related materials(nickel-chromiumironalloys)to intergranular stress corrosion cracking.1.2 This practice can be used to evaluate stainless steels orother materials in the“as received”condition or after beingsubjected to high-temperature service,482 to 815C(900 to1500F),for prolonged periods of time.1.3 This practice can be applied to wrought products,castings,and weld metal of stainless steels or other relatedmaterials to be used in environments containing sulfur orsulfides.Other materials capable of being sensitized can alsobe tested in accordance with this test.1.4 This practice may be used with a variety of stresscorrosion test specimens,surface finishes,and methods ofapplying stress.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.For more specificprecautionary statements,see Section 7.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterG1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)3G30 Practice for Making and Using U-Bend Stress-Corrosion Test Specimens3.Summary of Practice3.1 The stressed specimens are placed in the container alongwith a sensitized and stressedAISI Type 302(UNS S30200)orType 304(UNS S30400)stainless steel control specimen.Asufficient amount of the previously prepared polythionic acidsolution is added to the container to immerse the test speci-mens.A cover is placed on the container and the test is carriedout at room temperature.4.Significance and Use4.1 This environment provides a way of evaluating theresistance of stainless steels and related alloys to intergranularstress corrosion cracking.Failure is accelerated by the presenceof increasing amounts of intergranular precipitate.Results forthe polythionic acid test have not been correlated exactly withthose of intergranular corrosion tests.Also,this test may not berelevant to stress corrosion cracking in chlorides or causticenvironments.4.2 The polythionic acid environment may produce areas ofshallow intergranular attack in addition to the more localizedand deeper cracking mode of attack.Examination of failedspecimens is necessary to confirm that failure occurred bycracking rather than mechanical failure of reduced sections.5.Apparatus5.1 Any suitable glass or other transparent,inert containercan be used to contain the acid solution and stressed specimensduring the period of test at room temperature,22 to 25C(72to 77F).The container should be fitted with a removable topto reduce evaporation and to allow access to the stressedspecimen(or specimens)for the periodic inspection.1This 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 Nov.1,2015.Published November 2015.Originallyapproved in 1988.Last previous edition approved in 2010 as G3598(2010).DOI:10.1520/G0035-98R15.2For 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 6.Reagents6.1 Purity of ReagentsThe polythionic acid solution shallbe prepared using reagent grade sulfurous acid and technicalgrade hydrogen sulfide;or,distilled water,commercial gradesulfur dioxide,and technical grade hydrogen sulfide.6.2 Purity of WaterReagent water Type IV(SpecificationD1193)shall be used to prepare the test solutions.6.3 Wackenroders or Polythionic Acid Solution(1)4Aslow current of hydrogen sulfide is passed for an hour througha fritted glass tube into a flask containing chilled(0C,32F)6%sulfurous acid,after which the liquid is kept in thestoppered flask for 48 h at room temperature.This operat