1、Designation: F1624 09Standard 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
2、 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 in
3、itiatefracture 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 chemi
4、cals 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 s
5、tress 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
6、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
7、 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 withi
8、n 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
9、 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
10、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 treatme
11、nts, 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 a
12、ir, to measure the effectif residual hydrogen is in the steel because of the processing(IHE), or in a controlled environment, to measure the effect of1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.04 onH
13、ydrogen Embrittlement.Current edition approved Dec. 1, 2009. Published February 2010. Originallyapproved in 1995. Last previous edition approved in 2006 as F1624 06. DOI:10.1520/F1624-09.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.1Copyright ASTM I
14、nternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.hydrogen 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 acceptable inch-pound units shallbe regarded as the standard.
15、 The values stated in metric unitsmay not be exact equivalents. Conversion of the inch-poundunits by appropriate conversion factors is required to obtainexact equivalence.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility
16、 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 for Alloy Steel Socket-Head CapScrewsA490 Specification for Structural Bolts, Allo
17、y Steel, HeatTreated, 150 ksi Minimum Tensile StrengthB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of MechanicalTestingE8 Test Methods for Tension Testing of Metallic MaterialsE29 Pr
18、actice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE399 Test Method for Linear-Elastic Plane-Strain FractureToughness KIcof Metallic MaterialsE812 Test Method for Crack Strength of Slow-Bend Pre-cracked Charpy Specimens of High-Strength MetallicMaterials4E168
19、1 Test Method for Determining Threshold Stress In-tensity Factor for Environment-Assisted Cracking of Me-tallic MaterialsF519 Test Method for Mechanical Hydrogen EmbrittlementEvaluation of Plating/Coating Processes and Service Envi-ronmentsF606 Test Methods for Determining the Mechanical Prop-erties
20、 of Externally and Internally Threaded Fasteners,Washers, Direct Tension Indicators, and RivetsF2078 Terminology Relating to Hydrogen EmbrittlementTestingG5 Reference Test Method for Making Potentiostatic andPotentiodynamic Anodic Polarization MeasurementsG129 Practice for Slow Strain Rate Testing t
21、o Evaluate theSusceptibility of Metallic Materials to EnvironmentallyAssisted Cracking2.2 SAE Standards:J78 Self-Drilling Tapping Screws5J81 Thread Rolling Screws5J1237 Metric Thread Rolling Screws52.3 ANSI/ASME:B18.18.2M Inspection and Quality Assurance for High-Volume Machine Assembly Fasteners, 1
22、9876B18.18.3M Inspection and Quality Assurance for SpecialPurpose Fasteners, 19876B18.18.4M Inspection and Quality Assurance for Fastenersfor Highly Specialized Engineering Applications, 198762.4 Related Publications:ASTM STP 543, Hydrogen Embrittlement Testing, 19747ASTM STP 962, Hydrogen Embrittle
23、ment: Prevention andControl, 198573. Terminology3.1 SymbolsTerms not defined in this section can be foundin Terminologies F2078 and E6 and shall be considered asapplicable to the terms used in this test method.3.1.1 Papplied load.3.1.2 Pccritical load required to rupture a specimen usinga continuous
24、 loading rate.3.1.3 Picrack initiation load for a given loading andenvironmental condition using an incrementally increasingload under displacement control.3.1.4 Pththe invariant threshold load. Pthis the basis forcalculating the threshold stress or the threshold stress intensity.3.1.5 Pth-nthe thre
25、shold load at a specified loading rate.3.1.6 IHEInternal Hydrogen Embrittlement test con-ducted in air.3.1.7 EHEEnvironmental Hydrogen Embrittlement test conducted in a specified hydrogen-charging environment.3.1.8 ththreshold the lowest load at which subcriticalcracking can be detected.3.2 Irregula
26、r Geometry-Type Specimenstest sample otherthan a fracture mechanics-type specimen; examples include anotched round bar or fastener.3.2.1 s = applied stress.3.2.2 snet= net stress based on area at minimum diameter ofnotched round bar or per Test Method E812 for bend speci-mens.3.2.3 si= stress at cra
27、ck initiation.3.2.4 sth= threshold stress.3.2.5 sth-IHE= IHE threshold stress test conducted in air geometry dependent.3.2.6 sth-EHE= EHE threshold stress test conducted in aspecified hydrogen charging environment geometry depen-dent.3.2.7 Kth-IHE= IHE threshold stress intensity at a specifiedloadin
28、g rate test conducted in air not geometry depen-dent.3.2.8 Kth-EHE= EHE threshold stress intensity at a specifiedloading rate test conducted in a specified hydrogen chargingenvironment not geometry dependent.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custome
29、r Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.5Available from Society of Automotive Engineers (SAE), 400
30、 CommonwealthDr., Warrendale, PA 15096-0001.6Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.7Available from ASTM, 100 Barr Harbor Dr., PO Box C700, West Consho-hocken, PA 19428.F1624 0923.2.9 KISCC= invariant value of the threshold stress in
31、ten-sity for stress corrosion crackingtest conducted under opencircuit corrosion potential or freely corroding conditionsnotgeometry dependent.3.2.10 KIIHE= invariant value of the IHE threshold stressintensity test conducted in air not geometry dependent.3.2.11 KIEHE= invariant value of the EHE thre
32、shold stressintensity test conducted in a specified hydrogen chargingenvironment not geometry dependent equivalent toKIEAC.3.2.12 FFS = Fast Fracture Strength.3.2.13 SCG = Subcritical Crack Growth.4. Summary of Test Method4.1 The test method is based on determining the onset ofsubcritical crack grow
33、th with a step modified, incrementallyincreasing, slow strain rate test (Practice G129) under displace-ment control (3), (4), (5).4.2 This test method measures the load necessary to initiatea subcritical crack in the steel at progressively decreasingloading rates, for specimens of different geometry
34、 and differentenvironmental conditions.4.2.1 By progressively decreasing the loading rate, thethreshold stress can be determined.4.3 Four-point bending is used to maintain a constantmoment along the specimen. This condition is used to simplifythe calculation of stress or stress intensity for an irre
35、gular crosssection.4.4 The minimum or invariant value of the stress intensity(KISCC,KIIHE,orKIEHE) or stress for a given geometry withregard to the loading rate, is the threshold for the onset of crackgrowth due to hydrogen embrittlement.4.5 In tension (T) and bending (B), the onset of SCG as aresul
36、t of hydrogen in steel is identified by a concave decreasein load while holding the displacement constant.At net sectionyielding or above, a convex load drop is also observed.4.6 The displacement is incrementally increased in tensionor four-point bending and the resulting load is monitored.While the
37、 displacement is held constant, the onset of subcriti-cal crack growth is detected when the load decreases.4.7 The loading rate must be sufficiently slow to permithydrogen to diffuse and induce cracking that manifests itself asa degradation in strength (see Pollock (6) and (7).5. Significance and Us
38、e5.1 This test method is used for research, design, serviceevaluation, manufacturing control, and development. This testmethod quantitatively measures stress parameters that are usedin a design or failure analysis that takes into account the effectsof environmental exposure including that which occu
39、rs duringprocessing, such as plating (8) (ASTM STP 962).5.2 For plating processes, the value of sth-IHEis used tospecify quantitatively the maximum operating stress for agiven structure or product.5.3 For quality control purposes, an accelerated test isdevised that uses a specified loading rate, whi
40、ch is equal to orlower than the loading rate necessary to determine the thresh-old stress (see 8.1).5.4 For fasteners, the value of sth-IHEis used to specifyquantitatively the maximum stress during installation and inservice to avoid premature failure caused by residual hydrogenin the steel as a res
41、ult of processing.5.5 For fasteners, the value of sth-EHEis used to specifyquantitatively the maximum stress during installation and inservice to avoid failure from hydrogen absorbed during expo-sure to a specific environment.5.6 To measure the relative susceptibility of steels to hydro-gen pickup f
42、rom various fabrication processes, a single,selected, discriminating rate is used to rank the resistance ofvarious materials to hydrogen embrittlement.5.7 Annex A1 describes the application of this standard testmethod to hydrogen embrittlement testing of fasteners.6. Apparatus6.1 Testing MachineTest
43、ing machines shall be within theguidelines of calibration, force range, resolution, and verifica-tion of Practices E4.6.2 Gripping DevicesVarious types of gripping devicesshall be used in either tension or four-point bending to transmitthe measured load applied by the testing machine to the testspec
44、imen.6.3 Test EnvironmentThe test shall be conducted in air orany other suitable controlled environment using an appropriateinert container.6.3.1 Potentiostatic ControlThe corrosion potential of thespecimen can be controlled with a reference saturated calomelelectrode (SCE) or equivalent reference e
45、lectrode such asAg/AgCl in accordance with Test Method G5. The imposedpotential is typically cathodic, ranging from 0.0 to 1.2 Vversus SCE (VSCE) in a 3.5 weight percent NaCl solution (9).6.4 Equipment, such as RSLy8, for determining the onsetof SCG with a step modified, incrementally increasing, sl
46、owstrain rate test under displacement control.7. Sampling and Test Specimens7.1 SamplingFor research, design, and service evaluationand development, the sampling size depends on the specificrequirements of the investigator. For manufacturing control,loading rates shall be fixed, but statistically si
47、gnificant sam-pling sizes are used such as Test Methods F606, ANSI/ASMEB18.18.2M, B18.18.3M, or B18.18.4M and Test Method B602for fasteners. For other quality assurance tests, the samplingsize shall be in compliance with the requirements of thespecification.7.2 Test SpecimensThe test specimen should
48、 be classifiedas either fracture mechanics-type specimens or irregular-shaped specimens (10).7.2.1 Fracture mechanics-type specimens are defined instandards such as Test Method E399.NOTE 1The maximum stress used during fatigue precracking must beless than 60 % of any measured value of load for crack
49、 initiation for thedata to be valid.8Equipment specifically designed to conduct this test method is available atwww.fdi.nu/F1624 0937.2.2 Irregular geometry-type specimens shall be eitherspecimens as defined in standards such as Test Method F519 orspecimens from product. The product shall be tested eithersubstantially full size or as a machined specimen.8. Procedure8.1 Determination of Threshold Load (Pth):8.1.1 This test protocol requires that a minimum of threesamples be tested to establish the threshold load, Pth. Load onesampl
