1、Designation: G 142 98 (Reapproved 2004)Standard Test Method forDetermination of Susceptibility of Metals to Embrittlement inHydrogen Containing Environments at High Pressure, HighTemperature, or Both1This standard is issued under the fixed designation G 142; the number immediately following the desi
2、gnation 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a pro
3、cedure for determinationof tensile properties of metals in high pressure or hightemperature, or both, gaseous hydrogen-containing environ-ments. It includes accommodations for the testing of eithersmooth or notched specimens.1.2 This applies to all materials and product forms includ-ing, but not res
4、tricted to, wrought and cast materials.1.3 The values stated in SI units are to be regarded as thestandard.1.4 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 a
5、nd health practices and determine the applica-bility of regulatory limitations prior to use. See 6.1 foradditional information.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterE4 Practices for Force Verification of Testing MachinesE8 Test Methods for Tension Testing o
6、f Metallic MaterialsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG15 Terminology Relating to Corrosion and CorrosionTestingG 111 Guide for Corrosion Tests in High Temperature orHigh Pressure Environment, or BothG 129 Practice for Slow Strain Rate T
7、esting to Evaluate theSusceptibility of Metallic Materials to EnvironmentallyAssisted Cracking2.2 Military Standard:MIL-P-27201B Propellant, Hydrogen33. Terminology3.1 Definitions:3.1.1 control test, na mechanical test conducted in anenvironment that does not produce embrittlement of a testmaterial.
8、3.1.2 hydrogen embrittlement, nhydrogen induced crack-ing or severe loss of ductility caused by the presence ofhydrogen in the metal.3.1.3 Other definitions and terminology related to testingcan be found in Terminology G15.4. Summary of Test Method4.1 Specimens of selected materials are exposed to a
9、 gas-eous hydrogen containing environment at high pressure or hightemperature, or both, while being pulled to failure in uniaxialtension. The susceptibility to hydrogen embrittlement is evalu-ated through the determination of standard mechanical prop-erties in tension (that is, yield strength, ultim
10、ate tensilestrength, notched tensile strength, reduction in area or elonga-tion, or both). Comparison of these mechanical propertiesdetermined in a hydrogen-containing environment to thosedetermined in a non-embrittling environment (control test)provides a general index of susceptibility to cracking
11、 versus thematerials normal mechanical behavior.5. Significance and Use5.1 This test method provides a reliable prediction of theresistance or susceptibility, or both, to loss of material strengthand ductility as a result of exposure to hydrogen-containinggaseous environments. This test method is ap
12、plicable over abroad range of pressures, temperatures, and gaseous environ-ments. The results from this test method can be used toevaluate the effects of material composition, processing, andheat treatment as well as the effects of changes in environmentcomposition, temperature, and pressure. These
13、results may or1This test method is under the jurisdiction of ASTM Committee G01 onCorrosion of Metals and is the direct responsibility of Subcommittee G01.06 onEnvironmentally Assisted Cracking .Current edition approved May 1, 2004. Published May 2004. Originallyapproved in 1996. Last previous editi
14、on approved in 1998 as G 142 98.2For 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.3Available from Standardizati
15、on Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-50981Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.may not correlate with service experience for particular appli-cations. Furthermore, thi
16、s test method may not be suitable forthe evaluation of high temperature hydrogen attack in steelsunless suitable exposure time at the test conditions has takenplace prior to the initiation of tensile testing to allow for thedevelopment of internal blistering, decarburization or cracking,or both.6. A
17、pparatus6.1 Since this test method is intended to be conducted athigh pressures and may also involve high temperatures, theapparatus must be constructed to safely contain the testenvironment while being resistant to the embrittling effects ofhydrogen. Secondly, the test apparatus must be capable ofa
18、llowing introduction of the test gas, removal of air from thetest cell, and accurate performance of the tension test on thetest specimen. In cases where the tests are conducted atelevated temperatures, the apparatus must provide for heatingof the specimen and the test environment in direct contact w
19、iththe specimen.6.2 Fig. 2 shows a schematic representation of a typical testcell designed to conduct HP/HT gaseous hydrogen embrittle-ment experiments.4The typical components include:6.2.1 Metal Test CellThe test cell should be constructedfrom materials that have proven to have high resistance tohy
20、drogen embrittlement under the conditions. A list of poten-tial materials of construction is shown in Fig. 1.5Materialswith high values of tensile ratios (environment versus a controlenvironment) should be used. Materials with low values of thisparameter should be avoided.6.2.2 Closure and SealTo fa
21、cilitate operation of the testcell and tension testing, the closure should provide for rapidopening and closing of the test cell and reliable sealingcapabilities for hydrogen. This can include either metallic ornon-metallic materials with high resistance to hydrogen em-brittlement and degradation.6.
22、2.3 Gas Port(s)The gas port should be designed topromote flow and circulation of the gaseous test environments,inert gas purging and evacuation as required to produce theintended test environment. Usually two ports are used so thatflow-through capabilities are attained to facilitate these func-tions
23、.6.2.4 Electrical Feed-ThroughsIf very high temperatureconditions are required it may be advantageous to utilize aninternal heater to heat the test specimen and the gaseousenvironment in the immediate vicinity of the specimen. There-fore, a feed-through would be needed to reach an internalresistance
24、 or induction heater. These feed-throughs must alsoprovide electrical isolation from the test cell and internalfixtures, and maintain a seal to prevent leakage of the testenvironment. If external heaters are used, no electric feed-throughs would be required for testing.6.2.5 Tensile Feed-Through(s)T
25、o apply tensile loading tothe test specimen it is necessary to have feed-through(s) whichprovide linear motion and transmission of loads from anexternal source. Care must be taken to design such feed-throughs to have low friction to minimize errors due to frictionlosses when using externally applied
26、 loads. These are usuallydesigned to incorporate thermoplastic or elastomeric materials,or both. If elevated temperature tests are being conducted, then4R. D. Kane, “High Temperature and High Pressure,” Corrosion Tests andStandards, Ed. Robert Baboian, ASTM, West Conshohocken, PA.5Metals Handbook, V
27、ol 9, Corrosion, 9th Edition, ASM International, MetalsPark, OH, 1987, p. 1104.FIG. 1 Notched Tensile Strength (NTS) Ratio for Various Alloys in 35 to 69 MPa Gaseous Hydrogen versus Air Tested at RoomTemperatureG 142 98 (2004)2extreme care must be used in the selection of these materials toalso resi
28、st deterioration and loss of mechanical properties at thetest temperature.6.2.6 Pull RodThe pull rod works in combination with thetensile feed-through to provide for loading of the test speci-men. It is usually attached to a tensile testing machine on oneend and the tension specimen on the other. It
29、 should bedesigned to have adequate cross-sectional area to minimizecompliance in the loading system under the anticipated loads tobe used. Also, to minimize frictional forces in the seal andpromote sealing, it should be made with a highly polishedsurfaces 0.25 m (10 in.) RMS. It is possible to obta
30、in pullrod systems that are pressure balanced so specimen loadingfrom the internal pressure in the test cell can be minimized.6.2.7 Load CellLoad cells for conducting high pressuretensile tests may be two configurations:6.2.7.1 External load cells which are attached to the pull rodoutside of the tes
31、t cell, and6.2.7.2 Internal load cells which are either attached to thepull rod or grip assembly inside of the autoclave or areintegrated into the pull rod. When using external load cells it isimportant to correct load cell readings for frictional forces inthe pressure seal. Additionally, if non-pre
32、ssure balanced pullrods are used, compensation for pressure loading of thespecimen must be also performed.6.2.8 Electric Resistance or Induction Heater(s)Eitherinternal or external heaters can be used to obtain elevatedtemperature. For lower temperatures, and when using testenvironments containing r
33、eactive constituents in addition tohydrogen, external heating of the test cell is typically moreconvenient. At high temperatures, when using non-reactive orhydrogen gas environments, an internal heater can be used toheat only the test specimen and the gaseous environment in thevicinity of the test s
34、pecimen to limit power requirements andproblems with high temperature sealing and pressure contain-ment.6.2.9 GripsGrips shall provide for efficient and accuratetransfer of load from the pull rods to the test specimen. Gripsshould be designed to minimize compliance in the loadingsystem under the ant
35、icipated loads to pull the test specimen.6.2.10 Loading FixtureA fixture is used to react the loadused to pull the specimen. An internal fixture is shownschematically in Fig. 2.6.2.11 Testing MachinesTension testing machines usedfor conducting tests according to this test method shall conformto the
36、requirements of Practices E4. The loads used in testsshall be within the calibrated load ranges of the testingmachines in accordance with Practices E4.7. Reagents7.1 Purity of ReagentsReagent grade chemicals and ultralow oxygen gases (1 ppm) shall be used in all tests unless thetest environment is d
37、erived from a field or plant environment.If the test is to be conducted for aerospace propulsion appli-cations, the environment shall consist of hydrogen gas perMIL-P-27201B.7.2 If water is to be added to any test environment, distilledor deionized water conforming to Specification D 1193 TypeIV sha
38、ll be used.8. Test Environment8.1 Test environments can consist of either field or plantsamples or be prepared in the laboratory from chemicals andgases as indicated in Section 7.8.2 When testing in hydrogen containing environments,susceptibility to hydrogen embrittlement typically increaseswith dec
39、reasing oxygen content of the test environment.Therefore, strict procedures for deaeration shall be followedand periodically qualified for oxygen content as discussed inSections 9 and 11.8.3 For purposes of standardization, suggested standardizedpressures for hydrogen gas testing shall be 7 MPa, 35
40、MPa, and69 MPa. However, for materials evaluation for specific appli-cations, the test pressure should be equal to or greater than thatwhich represents the service conditions.FIG. 2 Hydrogen Tensions Test Autoclave for Various Alloys inHydrogen versus AirG 142 98 (2004)39. Sampling9.1 The procedure
41、for sampling mill products is typicallycovered in product or other specifications and is outside thescope of this document.9.2 Sampling of the test environment is recommended toconfirm that the test environment is in conformance with thistest method and attains the intended test conditions. Suchsamp
42、ling shall be conducted immediately prior to and aftertesting. The frequency of environmental sampling shall be asrequired to cover applicable product, purchase or in-housetesting specifications, or both.As a minimum requirement to bein compliance with this test method, however, sampling of thetest
43、environment shall be conducted at the start of testing andagain when any element of the test procedure or test system hasbeen changed or modified.10. Test Specimens10.1 Tension specimens shall be used for evaluation ofhydrogen embrittlement. These specimens shall conform to thedimensions and guideli
44、nes provided in Test Methods E8.However, in some cases, the material size, configuration, andform or the confines of various test cells may limit the actualdimensions of the test specimen. In such cases, the specimengeometry and dimensions shall be fully described. Take care toonly compare the resul
45、ts obtained from similar specimens.10.2 For purposes of standardizing the evaluation of mate-rials according to this test method, two standard test specimensshall be used: standard smooth tension specimen, and standardnotched tensile specimen. The dimensions of these specimensare given in Fig. 3a an
46、d Fig. 3b.10.3 Specimens shall be machined to have a minimalamount of cold work on the gage or notch surfaces. Total metalremoved in the last two passes shall be limited to a total of 0.05mm and have a surface finish of 0.25 m (10 in.) or better. Themethod of final machining of the gage section shou
47、ld be bygrinding (not turning) to avoid localized grooves and coldworked areas.11. Standardization11.1 To provide an indication when some inadvertent de-viation from the correct test conditions occurs, it is necessaryto test a control specimen of a material of known susceptibilityto hydrogen embritt
48、lement using the procedures given herein.This control material should exhibit an easily reproducibledegree of embrittlement.11.2 The control materials for tests conducted in a hydrogencontaining environment shall be as given below:11.2.1 Low ResistanceLow Alloy Steel: UNS G43400(austenitize at 900C
49、for 1 h plus water quench and temper at454C for 2 h).11.2.2 Intermediate ResistanceNickel Base Alloy: UNSN07718 (solution annealed at 954C for 1 h plus air cool; ageat 718C for 8 h plus furnace cool to 620C hold for 8 h plusair cool).11.2.3 High ResistanceStainless Steels: A 286AMS5737 (solution annealed at 893C for 1 h plus water quench andaged at 721C for 16 h plus air cool).12. Test Procedure12.1 Follow the basic guidelines for high pressure/hightemperature corrosion testing in Guide G 111 where applicable.12.2 Measure the initial specimen dimensi
