ASTM_G_150_-_13.pdf

Designation:G15013Standard Test Method forElectrochemical Critical Pitting Temperature Testing ofStainless Steels1This standard is issued under the fixed designation G150;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 covers a procedure for the evaluationof the resistance of stainless steel and related alloys to pittingcorrosion based on the concept of the determination of apotential independent critical pitting temperature(CPT).1.2 This test methods applies to wrought and cast productsincluding but not restricted to plate,sheet,tubing,bar,forgings,and welds,(see Note 1).NOTE1Examples of CPT measurements on sheet,plate,tubing,andwelded specimens for various stainless steels can be found in Ref(1).2Seethe research reports(Section 14).1.3 The standard parameters recommended in this testmethod are suitable for characterizing the CPT of austeniticstainless steels and other related alloys with a corrosionresistance ranging from that corresponding to solution an-nealed UNS S31600(Type 316 stainless steel)to solutionannealed UNS S31254(6%Mo stainless steel).1.4 This test method may be extended to stainless steels andother alloys related to stainless steel that have a CPT outsidethe measurement range given by the standard parametersdescribed in this test method.Appropriate test potential andsolution must then be determined.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 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:3D1193 Specification for Reagent WaterD1293 Test Methods for pH of WaterE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG5 Reference Test Method for Making PotentiodynamicAnodic Polarization MeasurementsG46 Guide for Examination and Evaluation of Pitting Cor-rosionG107 Guide for Formats for Collection and Compilation ofCorrosion Data for Metals for Computerized DatabaseInputG193 Terminology and Acronyms Relating to Corrosion3.Terminology3.1 Definitions:3.1.1 critical pitting temperature(CPT)the lowest tem-perature on the test surface at which stable propagating pittingoccurs under specified test conditions indicated by a rapidincrease beyond a set limit of the measured anodic currentdensity of the specimen.3.1.2 pitting potential rangethe range of measured poten-tials where pitting is initiated.This potential range only existsabove the minimum critical pitting temperature;see alsoAppendix X1.3.1.3 potential dependent CPTthe CPT determined at apotential within the pitting potential range of the testedmaterial;see also Appendix X1.1This test method is under the jurisdiction of G01 on Corrosion of Metals and isthe direct responsibility of Subcommittee G01.11 on Electrochemical Measurementsin Corrosion Testing.Current edition approved May 1,2013.Published May 2013.Originallyapproved in 1997.Last previous edition approved in 2010 as G15099(2010).DOI:10.1520/G0150-13.2The boldface numbers in parenthesis refer to the 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 3.1.4 potential independent CPT the CPT determined at apotential above the pitting potential range,but below thetranspassive potential;see also Appendix X1.3.1.5 temperature rampthe rate(C/min)at which the testtemperature is increased during the test.3.2 sign conventionsthe sign conventions used in thisprocedure are in agreement with Practice G3.3.3 Unless otherwise stated,this test method uses thegeneral terminology relating to corrosion and corrosion testingas defined in Terminology G193.4.Summary of Test Method4.1 The test method determines the potential independentcritical pitting temperature(CPT)by way of a potentiostatictechnique using a temperature scan and a specimen holder thatis designed to eliminate the occurrence of crevice corrosion(see Fig.1).The specimen is exposed,either entirely or in part,depending on te