ASTM G142-98
(Test Method)Standard Test Method for Determination of Susceptibility of Metals to Embrittlement in Hydrogen Containing Environments at High Pressure, High Temperature, or Both
Standard Test Method for Determination of Susceptibility of Metals to Embrittlement in Hydrogen Containing Environments at High Pressure, High Temperature, or Both
SCOPE
1.1 This test method covers a procedure for determination of tensile properties of metals in high pressure or high temperature, or both, gaseous hydrogen-containing environments. It includes accommodations for the testing of either smooth or notched specimens.
1.2 This applies to all materials and product forms including, but not restricted to, wrought and cast materials.
1.3 The values stated in SI units are to be regarded as the standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See 6.1 for additional information.
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Designation: G 142 – 98
Standard Test Method for
Determination of Susceptibility of Metals to Embrittlement in
Hydrogen Containing Environments at High Pressure, High
Temperature, or Both
This standard is issued under the fixed designation G 142; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope MIL-P-27201B Propellant, Hydrogen
1.1 This test method covers a procedure for determination
3. Terminology
of tensile properties of metals in high pressure or high
3.1 Definitions:
temperature, or both, gaseous hydrogen-containing environ-
3.1.1 control test, n—a mechanical test conducted in an
ments. It includes accommodations for the testing of either
environment that does not produce embrittlement of a test
smooth or notched specimens.
material.
1.2 This applies to all materials and product forms includ-
3.1.2 hydrogen embrittlement, n—hydrogen induced crack-
ing, but not restricted to, wrought and cast materials.
ing or severe loss of ductility caused by the presence of
1.3 The values stated in SI units are to be regarded as the
hydrogen in the metal.
standard.
3.1.3 Other definitions and terminology related to testing
1.4 This standard does not purport to address all of the
can be found in Terminology G 15.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Test Method
priate safety and health practices and determine the applica-
4.1 Specimens of selected materials are exposed to a gas-
bility of regulatory limitations prior to use. See 6.1 for
eous hydrogen containing environment at high pressure or high
additional information.
temperature, or both, while being pulled to failure in uniaxial
tension. The susceptibility to hydrogen embrittlement is evalu-
2. Referenced Documents
ated through the determination of standard mechanical prop-
2.1 ASTM Standards:
2 erties in tension (that is, yield strength, ultimate tensile
D 1193 Specification for Reagent Water
3 strength, notched tensile strength, reduction in area or elonga-
E 4 Practices for Force Verification of Testing Machines
3 tion, or both). Comparison of these mechanical properties
E 8 Test Methods for Tension Testing of Metallic Materials
determined in a hydrogen-containing environment to those
E 691 Practice for Conducting an Interlaboratory Study to
4 determined in a non-embrittling environment (control test)
Determine the Precision of a Test Method
provides a general index of susceptibility to cracking versus the
G 15 Terminology Relating to Corrosion and Corrosion
5 material’s normal mechanical behavior.
Testing
G 111 Guide for Corrosion Tests in High Temperature or
5. Significance and Use
High Pressure Environment, or Both
5.1 This test method provides a reliable prediction of the
G 129 Practice for Slow Strain Rate Testing to Evaluate the
resistance or susceptibility, or both, to loss of material strength
Susceptibility of Metallic Materials to Environmentally
5 and ductility as a result of exposure to hydrogen-containing
Assisted Cracking
gaseous environments. This test method is applicable over a
2.2 Military Standard:
broad range of pressures, temperatures, and gaseous environ-
ments. The results from this test method can be used to
This test method is under the jurisdiction of ASTM Committee G-1 on evaluate the effects of material composition, processing, and
Corrosion of Metals and is the direct responsibility of Subcommittee G01.06 on
heat treatment as well as the effects of changes in environment
Stress Corrosion Cracking and Corrosion Fatigue.
composition, temperature, and pressure. These results may or
Current edition approved April 10, 1998. Published September 1998.
Originally published as G 142–96. Last previous edition G 142–96.
Annual Book of ASTM Standards, Vol 11.01.
Annual Book of ASTM Standards, Vol 03.01.
4 6
Annual Book of ASTM Standards, Vol 14.02. Available from Standardization Documents, Order Desk, Bldg. 4 Section D,
Annual Book of ASTM Standards, Vol 03.02. 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G 142
may not correlate with service experience for particular appli- environment) should be used. Materials with low values of this
cations. Furthermore, this test method may not be suitable for parameter should be avoided.
the evaluation of high temperature hydrogen attack in steels
6.2.2 Closure and Seal—To facilitate operation of the test
unless suitable exposure time at the test conditions has taken
cell and tension testing, the closure should provide for rapid
place prior to the initiation of tensile testing to allow for the
opening and closing of the test cell and reliable sealing
development of internal blistering, decarburization or cracking,
capabilities for hydrogen. This can include either metallic or
or both.
non-metallic materials with high resistance to hydrogen em-
brittlement and degradation.
6. Apparatus
6.2.3 Gas Port(s)—The gas port should be designed to
6.1 Since this test method is intended to be conducted at
promote flow and circulation of the gaseous test environments,
high pressures and may also involve high temperatures, the
inert gas purging and evacuation as required to produce the
apparatus must be constructed to safely contain the test
intended test environment. Usually two ports are used so that
environment while being resistant to the embrittling effects of
flow-through capabilities are attained to facilitate these func-
hydrogen. Secondly, the test apparatus must be capable of
tions.
allowing introduction of the test gas, removal of air from the
6.2.4 Electrical Feed-Throughs—If very high temperature
test cell, and accurate performance of the tension test on the
conditions are required it may be advantageous to utilize an
test specimen. In cases where the tests are conducted at
internal heater to heat the test specimen and the gaseous
elevated temperatures, the apparatus must provide for heating
environment in the immediate vicinity of the specimen. There-
of the specimen and the test environment in direct contact with
the specimen. fore, a feed-through would be needed to reach an internal
resistance or induction heater. These feed-throughs must also
6.2 Fig. 1 shows a schematic representation of a typical test
cell designed to conduct HP/HT gaseous hydrogen embrittle- provide electrical isolation from the test cell and internal
ment experiments. The typical components include: fixtures, and maintain a seal to prevent leakage of the test
6.2.1 Metal Test Cell—The test cell should be constructed
environment. If external heaters are used, no electric feed-
from materials that have proven to have high resistance to
throughs would be required for testing.
hydrogen embrittlement under the conditions. A list of poten-
6.2.5 Tensile Feed-Through(s)—To apply tensile loading to
tial materials of construction is shown in Fig. 2. Materials
the test specimen it is necessary to have feed-through(s) which
with high values of tensile ratios (environment versus a control
provide linear motion and transmission of loads from an
external source. Care must be taken to design such feed-
throughs to have low friction to minimize errors due to friction
losses when using externally applied loads. These are usually
R. D. Kane, “High Temperature and High Pressure”, Corrosion Tests and
Standards, Ed. Robert Baboian, ASTM, West Conshohocken, PA.
designed to incorporate thermoplastic or elastomeric materials,
Metals Handbook, Vol 9, Corrosion, 9th Edition, ASM International, Metals
or both. If elevated temperature tests are being conducted, then
Park, OH, 1987, p. 1104.
FIG. 2 Notched Tensile Strength (NTS) Ratio for Various Alloys in 35 to 69 MPa Gaseous Hydrogen versus Air Tested at Room
Temperature
G 142
6.2.7.2 Internal load cells which are either attached to the
pull rod or grip assembly inside of the autoclave or are
integrated into the pull rod. When using external load cells it is
important to correct load cell readings for frictional forces in
the pressure seal. Additionally, if non-pressure balanced pull
rods are used, compensation for pressure loading of the
specimen must be also performed.
6.2.8 Electric Resistance or Induction Heater(s)—Either
internal or external heaters can be used to obtain elevated
temperature. For lower temperatures and when using test
environments containing reactive constituents in addition to
hydrogen, external heating of the test cell is typically more
convenient. At high temperatures when using non-reactive or
hydrogen gas environments, an internal heater can be used to
heat only the test specimen and the gaseous environment in the
vicinity of the test specimen to limit power requirements and
problems with high temperature sealing and pressure contain-
ment.
6.2.9 Grips—Grips shall provide for efficient and accurate
transfer of load from the pull rods to the test specimen. Grips
should be designed to minimize compliance in the loading
system under the anticipated loads to pull the test specimen.
6.2.10 Loading Fixture—A fixture is used to react the load
used to pull the specimen. An internal fixture is shown
schematically in Fig. 1.
6.2.11 Testing Machines—Tension testing machines used
for conducting tests according to this test method shall conform
to the requirements of Practices E 4. The loads used in tests
shall be within the calibrated load ranges of the testing
machines in accordance with Practices E 4.
7. Reagents
7.1 Purity of Reagents—Reagent grade chemicals and ultra
low oxygen gases (<1 ppm) shall be used in all tests unless the
test environment is derived from a field or plant environment.
If the test is to be conducted for aerospace propulsion appli-
FIG. 1 Hydrogen Tensions Test Autoclave for Various Alloys in
cations, the environment shall consist of hydrogen gas per
Hydrogen versus Air
MIL-P-27201B.
7.2 If water is to be added to any test environment, distilled
or deionized water conforming to Specification D 1193 Type
extreme care must be used in the selection of these materials to
IV shall be used.
also resist deterioration and loss of mechanical properties at the
test temperature.
8. Test Environment
6.2.6 Pull Rod—The pull rod works in combination with the
8.1 Test environments can consist of either field or plant
tensile feed-through to provide for loading of the test speci-
samples or be prepared in the laboratory from chemicals and
men. It is usually attached to a tensile testing machine on one
gases as indicated in Section 7.
end and the tension specimen on the other. It should be
8.2 When testing in hydrogen containing environments,
designed to have adequate cross-sectional area to minimize
susceptibility to hydrogen embrittlement typically increases
compliance in the loading system under the anticipated loads to
with decreasing oxygen content of the test environment.
be used. Also, to minimize frictional forces in the seal and
Therefore, strict procedures for deaeration shall be followed
promote sealing, it should be made with a highly polished
and periodically qualified for oxygen content as discussed in
surfaces [<0.25 μm (10 μin.) RMS]. It is possible to obtain pull
Sections 9 and 11.
rod systems that are pressure balanced so specimen loading
from the internal pressure in the test cell can be minimized. 8.3 For purposes of standardization, suggested standardized
6.2.7 Load Cell—Load cells for conducting high pressure pressures for hydrogen gas testing shall be 7 MPa, 35 MPa, and
tensile tests may be two configurations: 69 MPa. However, for materials evaluation for specific appli-
6.2.7.1 External load cells which are attached to the pull rod cations, the test pressure should be equal to or greater than that
outside of the test cell, and which represents the service conditions.
G 142
9. Sampling
9.1 The procedure for sampling mill products is typically
covered in product or other specifications and is outside the
scope of this document.
9.2 Sampling of the test environment is recommended to
confirm that the test environment is in conformance with this
test method and attains the intended test conditions. Such
sampling shall be conducted immediately prior to and after
testing. The frequency of environmental sampling shall be as
required to cover applicable product, purchase or in-house
testing specifications, or both. As a minimum requirement to be
in compliance with this test method, however, sampling of the
test environment shall be conducted at the start of testing and
again when any element of the test procedure or test system has
been changed or modified.
10. Test Specimens
10.1 Tension specimens shall be used for evaluation of
hydrogen embrittlement. These specimens shall conform to the
dimensions and guidelines provided in Test Methods E 8.
However, in some cases, the material size, configuration and
form or the confines of various test cells may limit the actual
dimensions of the test specimen. In such cases, the specimen
geometry and dimensions shall be fully described. Take care to
only compare the results obtained from similar specimens.
10.2 For purposes of standardizing the evaluation of mate-
rials according to this test method, two standard test specimens
FIG. 3 Standard Tension Specimens (a) Smooth and (b) Notched
shall be used: standard smooth tension specimen, and standard
notched tensile specimen. The dimensions of these specimens
12. Test Procedure
are given in Fig. 3a and Fig. 3 b.
12.1 Follow the basic guidelines for high pressure/high
10.3 Specimens shall be machined to have a minimal
temperature corrosion testing in Guide G 111 where applicable.
amount of cold work on the gage or notch surfaces. Total metal
12.2 Measure the initial specimen dimensions. For smooth
removed in the last two passes shall be limited to a total of 0.05
tensile specimens, the dimensions measured are gage length
mm and have a surface finish of 0.25 μm (10 μin.) or better. The
and diameter. For notched specimens, the dimensions are gage
method of final machining of the gage section should be by
and notch diameter.
grinding (not turning) to avoid localized grooves and cold
12.3 Degrease and clean the specimen. Once cleaned the
worked areas.
specimen shall not be handled with bare hands.
12.4 Mount the specimen in the test cell using suitable grips
11. Standardi
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