ASTM_G_41_-_90_2013.pdf

Designation:G4190(Reapproved 2013)Standard Practice forDetermining Cracking Susceptibility of Metals ExposedUnder Stress to a Hot Salt Environment1This standard is issued under the fixed designation G41;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 testing metals forembrittlement and cracking susceptibility when exposed understress to a hot salt environment.This practice can be used fortesting all metals for which service conditions dictate the needfor such information.The test procedures described herein aregenerally applicable to all metal alloys;required adjustments inenvironmental variables(temperature,stress)to characterize agiven materials system should be made.This practice describesthe environmental conditions and degree of control required,and suggests means for obtaining this desired control.1.2 This practice can be used both for alloy screening fordetermination of relative susceptibility to embrittlement andcracking,and for the determination of time-temperature-stressthreshold levels for onset of embrittlement and cracking.However,certain specimen types are more suitable for each ofthese two types of characterizations.NOTE1This practice relates solely to the performance of the exposuretest.No detailed description concerning preparation and analysis ofspecimen types is offered.However,the optimum sample design may beone that uses the same type of stress encountered in service loadingsituations.Standards describing principal types of stress corrosionspecimens,their preparation,and analysis,include Practices G30,G38,and G39.1.3 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 specificsafety hazard statements see Section 8.)2.Referenced Documents2.1 ASTM Standards:2D1141 Practice for the Preparation of Substitute OceanWaterD1193 Specification for Reagent WaterG1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG30 Practice for Making and Using U-Bend Stress-Corrosion Test SpecimensG38 Practice for Making and Using C-Ring Stress-Corrosion Test SpecimensG39 Practice for Preparation and Use of Bent-Beam Stress-Corrosion Test SpecimensG49 Practice for Preparation and Use of Direct TensionStress-Corrosion Test Specimens3.Summary of Practice3.1 The hot salt test consists of exposing a stressed,salt-coated test specimen to elevated temperature for variouspredetermined lengths of time,depending on the alloy,stresslevel,temperature,and selected damage criterion(that is,embrittlement,cracking,or rupture,or a combination thereof).Exposures are normally carried out in laboratory ovens orfurnaces with associated loading equipment for stressing ofspecimens.3.2 The ovens are provided with facilities to circulate air atvarious flow rates and ambient pressure.However,for certainspecific applications,airflow and pressure may be adjusted toobtain information on material behavior in simulated serviceenvironments.Exposure temperatures and stress levels aregenerally selected on the basis of mechanical property data fora given alloy,or of expected service conditions,or both.4.Significance and Use4.1 The hot salt test as applied to metals is utilized as asecondary design consideration indicator,as cracking has beenshown to occur in laboratory tests simulating possible serviceconditions.Although limited evidence exists linking this phe-nomenon to actual service failures,cracking under stress in ahot salt environment should be recognized as a potential designcontrolling factor.4.2 The hot salt test is not to be misconstrued as beingrelated to the stress corrosion cracking of materials in other1This 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 1974.Last previous edition approved in 2006 as G41 90(2006).DOI:10.1520/G0041-90R13.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 environments.It is considered solely as a test in an environ-ment that might be encountered in service.4.3 Because hot salt cracking under stress is considered asecondary design consideration and service failures have notb