ASTM_F_1624_-_12.pdf

Designation:F162412Standard Test Method forMeasurement of Hydrogen Embrittlement Threshold in Steelby the Incremental Step Loading Technique1This standard is issued under the fixed designation F1624;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.INTRODUCTIONHydrogen embrittlement is caused by the introduction of hydrogen into steel that can initiatefracture as a result of residual stress or in service when external stress is applied(1).2The hydrogencan be generated during cleaning or plating processes or the exposure of cathodically protected steelparts to a service environment including fluids,cleaning treatments,or maintenance chemicals thatmay contact the surface of steel components.This method can be used to rapidly determine the effectsof residual hydrogen in a part caused by processing or quantify the relative susceptibility of a materialunder a fixed set of hydrogen-charging conditions.The combined residual and applied stress above which time-delayed fracture will occur(finite life)or below which fracture will never occur(infinite life)is called the threshold stress or threshold stressintensity(K)for precracked specimens.Historically,sustained load time-to-failure tests have beenconducted on notched bars to determine the threshold stress for the onset of hydrogen stress cracking.This technique may require 12 to 14 specimens and several high-load capacity machines.Forprecracked specimens,the run-out time can be as long as four to five years per U.S.Navy requirementsfor low-strength steels at 33 to 35 HRC.In Test Method E1681,more than 10 000 h(one year)arespecified for low-strength steel(175 ksi).This standard provides an accelerated method to measure the threshold stress or threshold stressintensity as defined in Test Method E1681 for the onset of hydrogen stress cracking in steel within oneweek on only one machine.The specific application of this standard to hydrogen embrittlement testingof fasteners is described in Annex A1.1.Scope1.1 This test method establishes a procedure to measure thesusceptibility of steel to a time-delayed failure such as thatcaused by hydrogen.It does so by measuring the threshold forthe onset of subcritical crack growth using standard fracturemechanics specimens,irregular-shaped specimens such asnotched round bars,or actual product such as fasteners(2)(threaded or unthreaded)springs or components as identified inSAE J78,J81,and J1237.1.2 This test method is used to evaluate quantitatively:1.2.1 The relative susceptibility of steels of different com-position or a steel with different heat treatments;1.2.2 The effect of residual hydrogen in the steel as a resultof processing,such as melting,thermal mechanical working,surface treatments,coatings,and electroplating;1.2.3 The effect of hydrogen introduced into the steel causedby external environmental sources of hydrogen,such as fluidsand cleaners maintenance chemicals,petrochemical products,and galvanic coupling in an aqueous environment.1.3 The test is performed either in air,to measure the effectif residual hydrogen is in the steel because of the processing(IHE),or in a controlled environment,to measure the effect ofhydrogen introduced into the steel as a result of the externalsources of hydrogen(EHE)as detailed in ASTM STP 543.1.4 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.NOTE1The values stated in metric units may not be exact equivalents.Conversion of the inch-pound units by appropriate conversion factors isrequired to obtain exact equivalence.1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.04 onHydrogen Embrittlement.Current edition approved Aug.1,2012.Published November 2012.Originallyapproved in 1995.Last previous edition approved in 2009 as F1624 09.DOI:10.1520/F1624-12.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 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:3A574 Specification forAlloy Steel Socket-Head Cap ScrewsA490 Specification for Structural Bolts,Alloy Steel,HeatTreated,150 ksi Minimum Tensile StrengthB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsE4 Pract