1、Designation: F1624 09 F1624 12Standard 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 o
2、r, 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 th
3、at can initiatefracture as a result of residual stress or in service when external stress is applied (1).2 The hydrogencan be generated during cleaning or plating processes or the exposure of cathodically protected steelparts to a service environment including fluids, cleaning treatments, or mainten
4、ance 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
5、 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 notche
6、d 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 a
7、t 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 s
8、teel 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 the susceptibility of steel to a time-delayed failure such as that causedby hydrog
9、en. It does so by measuring the threshold for the onset of subcritical crack growth using standard fracture mechanicsspecimens, irregular-shaped specimens such as notched round bars, or actual product such as fasteners (2) (threaded or unthreaded)springs or components as identified in SAE J78, J81,
10、and J1237.1.2 This test method is used to evaluate quantitatively:1.2.1 The relative susceptibility of steels of different composition or a steel with different heat treatments;1.2.2 The effect of residual hydrogen in the steel as a result of processing, such as melting, thermal mechanical working,
11、surfacetreatments, coatings, and electroplating;1.2.3 The effect of hydrogen introduced into the steel caused by external environmental sources of hydrogen, such as fluids andcleaners maintenance chemicals, petrochemical products, and galvanic coupling in an aqueous environment.1.3 The test is perfo
12、rmed either in air, to measure the effect if residual hydrogen is in the steel because of the processing (IHE),or in a controlled environment, to measure the effect of hydrogen introduced into the steel as a result of the external sources ofhydrogen (EHE) as detailed in ASTM STP 543.1 This test meth
13、od is under the jurisdiction of ASTM Committee F07 on Aerospace and Aircraft and is the direct responsibility of Subcommittee F07.04 on HydrogenEmbrittlement.Current edition approved Dec. 1, 2009Aug. 1, 2012. Published February 2010 November 2012. Originally approved in 1995. Last previous edition a
14、pproved in 20062009as F1624 06.F1624 09. DOI: 10.1520/F1624-09.10.1520/F1624-12.2 The boldface numbers in parentheses refer to the list of references at the end of this standard.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what c
15、hanges have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the of
16、ficial document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.4 The values stated in acceptable inch-pound units shall are to be regarded as the standard. The values stated in metric unitsmay not be exact equivalents. Conversion o
17、f the inch-pound units by appropriate conversion factors is required to obtain exactequivalence. given in parentheses are mathematical conversions to SI units that are provided for information only and are notconsidered standard.NOTE 1The values stated in metric units may not be exact equivalents. C
18、onversion of the inch-pound units by appropriate conversion factors isrequired to obtain exact equivalence.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety a
19、nd health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3A574 Specification for Alloy Steel Socket-Head Cap ScrewsA490 Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile StrengthB602 Test
20、Method for Attribute Sampling of Metallic and Inorganic CoatingsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE8 Test Methods for Tension Testing of Metallic MaterialsE29 Practice for Using Significant Digits in Test Data to Determine
21、Conformance with SpecificationsE399 Test Method for Linear-Elastic Plane-Strain Fracture Toughness KIc of Metallic MaterialsE812 Test Method for Crack Strength of Slow-Bend Precracked Charpy Specimens of High-Strength Metallic Materials(Withdrawn 2005)4E1681 Test Method for Determining Threshold Str
22、ess Intensity Factor for Environment-Assisted Cracking of Metallic MaterialsF519 Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Service EnvironmentsF606 Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fastene
23、rs, Washers, DirectTension Indicators, and RivetsF2078 Terminology Relating to Hydrogen Embrittlement TestingG5 Reference Test Method for Making Potentiostatic and Potentiodynamic Anodic Polarization MeasurementsG129 Practice for Slow Strain Rate Testing to Evaluate the Susceptibility of Metallic Ma
24、terials to Environmentally AssistedCracking2.2 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, 19876B18.18.3M Inspection and Quality Assura
25、nce for Special Purpose Fasteners, 19876B18.18.4M Inspection and Quality Assurance for Fasteners for Highly Specialized Engineering Applications, 198762.4 Related Publications:ASTM STP 543, Hydrogen Embrittlement Testing, 19747ASTM STP 962, Hydrogen Embrittlement: Prevention and Control, 198573. Ter
26、minology3.1 SymbolsTerms not defined in this section can be found in 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 using a continuous loading rate.3.1.3 Picrack initiation
27、 load for a given loading and environmental condition using an incrementally increasing load underdisplacement control.3.1.4 Pththe invariant threshold load. Pth is the basis for calculating the threshold stress or the threshold stress intensity.3.1.5 Pth-nthe threshold load at a specified loading r
28、ate.3 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 The last approved version of this historical standar
29、d is referenced on www.astm.org.5 Available from Society of Automotive Engineers (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001.6 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.7 Available from ASTM, 100 Barr Harbor Dr., PO Box C700
30、, West Conshohocken, PA 19428.F1624 1223.1.6 IHEInternal Hydrogen Embrittlement test conducted 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 subcritical cracking can be detected.3.2 Irregula
31、r Geometry-Type Specimenstest sample other than a fracture mechanics-type specimen; examples include anotched round bar or fastener.3.2.1 = applied stress.3.2.2 net = net stress based on area at minimum diameter of notched round bar or per Test Method E812 for bend specimens.3.2.3 i = stress at crac
32、k initiation.3.2.4 th = threshold stress.3.2.5 th-IHE = IHE threshold stress test conducted in air geometry dependent.3.2.6 th-EHE = EHE threshold stress test conducted in a specified hydrogen charging environment geometry dependent.3.2.7 Kth-IHE = IHE threshold stress intensity at a specified loadi
33、ng rate test conducted in air not geometry dependent.3.2.8 Kth-EHE = EHE threshold stress intensity at a specified loading rate test conducted in a specified hydrogen chargingenvironment not geometry dependent.3.2.9 KISCC = invariant value of the threshold stress intensity for stress corrosion crack
34、ingtest conducted under open circuitcorrosion potential or freely corroding conditionsnot geometry dependent.3.2.10 KIIHE = invariant value of the IHE threshold stress intensity test conducted in air not geometry dependent.3.2.11 KIEHE = invariant value of the EHE threshold stress intensity test con
35、ducted in a specified hydrogen chargingenvironment not geometry dependent equivalent to KIEAC.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 of subcritical crack growth with a step modified, inc
36、rementally increasing,slow strain rate test (Practice G129) under displacement control (3), (4), (5).4.2 This test method measures the load necessary to initiate a subcritical crack in the steel at progressively decreasing loadingrates, for specimens of different geometry and different environmental
37、 conditions.4.2.1 By progressively decreasing the loading rate, the threshold stress can be determined.4.3 Four-point bending is used to maintain a constant moment along the specimen. This condition is used to simplify thecalculation of stress or stress intensity for an irregular cross section.4.4 T
38、he minimum or invariant value of the stress intensity (KISCC, KIIHE, or KIEHE) or stress for a given geometry with regardto the loading rate, is the threshold for the onset of crack growth due to hydrogen embrittlement.4.5 In tension (T) and bending (B), the onset of SCG as a result of hydrogen in s
39、teel is identified by a concave decrease in loadwhile holding the displacement constant. At net section yielding or above, a convex load drop is also observed.4.6 The displacement is incrementally increased in tension or four-point bending and the resulting load is monitored. While thedisplacement i
40、s held constant, the onset of subcritical crack growth is detected when the load decreases.4.7 The loading rate must be sufficiently slow to permit hydrogen to diffuse and induce cracking that manifests itself as adegradation in strength (see Pollock (6) and (7).5. Significance and Use5.1 This test
41、method is used for research, design, service evaluation, manufacturing control, and development. This test methodquantitatively measures stress parameters that are used in a design or failure analysis that takes into account the effects ofenvironmental exposure including that which occurs during pro
42、cessing, such as plating (8) (ASTM STP 962).5.2 For plating processes, the value of th-IHE is used to specify quantitatively the maximum operating stress for a givenstructure or product.5.3 For quality control purposes, an accelerated test is devised that uses a specified loading rate, which is equa
43、l to or lower thanthe loading rate necessary to determine the threshold stress (see 8.1).5.4 For fasteners, the value of th-IHE is used to specify quantitatively the maximum stress during installation and in service toavoid premature failure caused by residual hydrogen in the steel as a result of pr
44、ocessing.5.5 For fasteners, the value of th-EHE is used to specify quantitatively the maximum stress during installation and in serviceto avoid failure from hydrogen absorbed during exposure to a specific environment.5.6 To measure the relative susceptibility of steels to hydrogen pickup from variou
45、s fabrication processes, a single, selected,discriminating rate is used to rank the resistance of various materials to hydrogen embrittlement.5.7 Annex A1 describes the application of this standard test method to hydrogen embrittlement testing of fasteners.F1624 1236. Apparatus6.1 Testing MachineTes
46、ting machines shall be within the guidelines of calibration, force range, resolution, and verification ofPractices E4.6.2 Gripping DevicesVarious types of gripping devices shall be used in either tension or four-point bending to transmit themeasured load applied by the testing machine to the test sp
47、ecimen.6.3 Test EnvironmentThe test shall be conducted in air or any other suitable controlled environment using an appropriate inertcontainer.6.3.1 Potentiostatic ControlThe corrosion potential of the specimen can be controlled with a reference saturated calomelelectrode (SCE) or equivalent referen
48、ce electrode such as Ag/AgCl in accordance with Test Method G5. The imposed potential istypically cathodic, ranging from 0.0 to 1.2 V versus SCE (VSCE) in a 3.5 weight percent NaCl solution (9).6.4 Equipment, such as RSLRSL (trademarked),8, for determining the onset of SCG with a step modified, incr
49、ementallyincreasing, slow strain rate test under displacement control.7. Sampling and Test Specimens7.1 SamplingFor research, design, and service evaluation and development, the sampling size depends on the specificrequirements of the investigator. For manufacturing control, loading rates shall be fixed, but statistically significant sampling sizesare used such as Test Methods F606, ANSI/ASME B18.18.2M, B18.18.3M, or B18.18.4M and Test Method B602 for fasteners.For other quality assurance tests, the sampling size s
