ASTM G123-00(2005)
(Test Method)Standard Test Method for Evaluating Stress-Corrosion Cracking of Stainless Alloys with Different Nickel Content in Boiling Acidified Sodium Chloride Solution
Standard Test Method for Evaluating Stress-Corrosion Cracking of Stainless Alloys with Different Nickel Content in Boiling Acidified Sodium Chloride Solution
SIGNIFICANCE AND USE
This test method is designed to compare alloys and may be used as one method of screening materials prior to service. In general, this test method is more useful for stainless steels than the boiling magnesium chloride test of Practice G 36. The boiling magnesium chloride test cracks materials with the nickel levels found in relatively resistant austenitic and duplex stainless steels, thus making comparisons and evaluations for many service environments difficult.
This test method is intended to simulate cracking in water, especially cooling waters that contain chloride. It is not intended to simulate cracking that occurs at high temperatures (greater than 200°C or 390°F) with chloride or hydroxide.
Note 1—The degree of cracking resistance found in full-immersion tests may not be indicative of that for some service conditions comprising exposure to the water-line or in the vapor phase where chlorides may concentrate.
Correlation with service experience should be obtained when possible. Different chloride environments may rank materials in a different order.
In interlaboratory testing, this test method cracked annealed UNS S30400 and S31600 but not more resistant materials, such as annealed duplex stainless steels or higher nickel alloys, for example, UNS N08020 (for example 20Cb-34 stainless). These more resistant materials are expected to crack when exposed to Practice G 36 as U-bends. Materials which withstand this sodium chloride test for a longer period than UNS S30400 or S31600 may be candidates for more severe service applications.
The repeatability and reproducibility data from Section 12 and Appendix X1 must be considered prior to use. Interlaboratory variation in results may be expected as occurs with many corrosion tests. Acceptance criteria are not part of this test method and if needed are to be negotiated by the user and the producer.
SCOPE
1.1 This test method describes a procedure for conducting stress-corrosion cracking tests in an acidified boiling sodium chloride solution. This test method is performed in 25% (by mass ) sodium chloride acidified to pH 1.5 with phosphoric acid. This test method is concerned primarily with the test solution and glassware, although a specific style of U-bend test specimen is suggested.
1.2 This test method is designed to provide better correlation with chemical process industry experience for stainless steels than the more severe boiling magnesium chloride test of Practice G36. Some stainless steels which have provided satisfactory service in many environments readily crack in Practice G36, but have not cracked during interlaboratory testing using this sodium chloride test method.
1.3 This boiling sodium chloride test method was used in an interlaboratory test program to evaluate wrought stainless steels, including duplex (ferrite-austenite) stainless and an alloy with up to about 33% nickel. It may also be employed to evaluate these types of materials in the cast or welded conditions.
1.4 This test method detects major effects of composition, heat treatment, microstructure, and stress on the susceptibility of materials to chloride stress-corrosion cracking. Small differences between samples such as heat-to-heat variations of the same grade are not likely to be detected.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.6 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. For specific hazard statements, see Section 7.
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Standards Content (Sample)
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Designation: G123 – 00 (Reapproved 2005)
Standard Test Method for
Evaluating Stress-Corrosion Cracking of Stainless Alloys
with Different Nickel Content in Boiling Acidified Sodium
Chloride Solution
This standard is issued under the fixed designation G123; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope bility of regulatory limitations prior to use. For specific hazard
statements, see Section 8.
1.1 This test method covers a procedure for conducting
stress-corrosion cracking tests in an acidified boiling sodium
2. Referenced Documents
chloride solution. This test method is performed in 25% (by
2.1 ASTM Standards:
mass) sodium chloride acidified to pH 1.5 with phosphoric
D1193 Specification for Reagent Water
acid. This test method is concerned primarily with the test
E8 Test Methods for Tension Testing of Metallic Materials
solutionandglassware,althoughaspecificstyleofU-bendtest
E691 Practice for Conducting an Interlaboratory Study to
specimen is suggested.
Determine the Precision of a Test Method
1.2 This test method is designed to provide better correla-
G15 Terminology Relating to Corrosion and Corrosion
tion with chemical process industry experience for stainless
Testing
steels than the more severe boiling magnesium chloride test of
G16 Guide forApplying Statistics toAnalysis of Corrosion
Practice G36. Some stainless steels which have provided
Data
satisfactory service in many environments readily crack in
G30 Practice for Making and Using U-Bend Stress-
Practice G36, but have not cracked during interlaboratory
2 Corrosion Test Specimens
testing using this sodium chloride test method.
G36 Practice for Evaluating Stress-Corrosion-Cracking Re-
1.3 Thisboilingsodiumchloridetestmethodwasusedinan
sistance of Metals and Alloys in a Boiling Magnesium
interlaboratory test program to evaluate wrought stainless
Chloride Solution
steels, including duplex (ferrite-austenite) stainless and an
G49 Practice for Preparation and Use of Direct Tension
alloywithuptoabout33%nickel.Itmayalsobeemployedto
Stress-Corrosion Test Specimens
evaluate these types of materials in the cast or welded
G107 Guide for Formats for Collection and Compilation of
conditions.
Corrosion Data for Metals for Computerized Database
1.4 This test method detects major effects of composition,
Input
heat treatment, microstructure, and stress on the susceptibility
of materials to chloride stress-corrosion cracking. Small dif-
3. Terminology
ferencesbetweensamplessuchasheat-to-heatvariationsofthe
3.1 Definitions:
same grade are not likely to be detected.
3.1.1 For definitions of corrosion-related terms used in this
1.5 The values stated in SI units are to be regarded as the
test method, see Terminology G15.
standard. The values given in parentheses are for information
only.
4. Summary of Test Method
1.6 This standard does not purport to address all of the
4.1 Asolutionof25%sodiumchloride(by mass)inreagent
safety concerns, if any, associated with its use. It is the
water is mixed, and the pH is adjusted to 1.5 with phosphoric
responsibility of the user of this standard to establish appro-
acid. The solution is boiled and U-bends (or other stressed
priate safety and health practices and determine the applica-
specimens) are exposed in fresh solution for successive one-
week periods.
4.2 The test may be continued for as many weeks as
This test method is under the jurisdiction of ASTM Committee G01 on
Corrosion of Metals and is the direct responsibility of Subcommittee G01.06 on
necessary, but six weeks (about 1000 h) or less are expected to
Environmentally Assisted Cracking.
Current edition approved Oct. 1, 2005. Published October 2005. Originally
approved in 1994. Last previous edition approved in 2000 as G123–00. DOI:
10.1520/G0123-00R05. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Supporting data (including UNS S30400, S31600, S32550, and N08020) have contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
been filed atASTM International Headquarters and may be obtained by requesting Standards volume information, refer to the standard’s Document Summary page on
Research Report G01-1013. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G123 – 00 (2005)
be sufficient to crack susceptible materials. Longer exposures
provide greater assurance of resistance for those materials
which do not crack.
4.3 It is recommended that samples of a susceptible mate-
rial, for example, UNS S30400 or S31600 (Type 304 or Type
316 stainless, respectively), be included as a control when
more resistant materials are evaluated.
5. Significance and Use
5.1 Thistestmethodisdesignedtocomparealloysandmay
be used as one method of screening materials prior to service.
In general, this test method is more useful for stainless steels
than the boiling magnesium chloride test of Practice G36. The
boiling magnesium chloride test cracks materials with the
nickel levels found in relatively resistant austenitic and duplex
stainless steels, thus making comparisons and evaluations for
many service environments difficult.
5.2 This test method is intended to simulate cracking in
water, especially cooling waters that contain chloride. It is not
intended to simulate cracking that occurs at high temperatures
(greater than 200°C or 390°F) with chloride or hydroxide.
NOTE 1—The degree of cracking resistance found in full-immersion
testsmaynotbeindicativeofthatforsomeserviceconditionscomprising
exposure to the water-line or in the vapor phase where chlorides may
concentrate.
5.3 Correlation with service experience should be obtained
when possible. Different chloride environments may rank
materials in a different order.
5.4 In interlaboratory testing, this test method cracked
annealed UNS S30400 and S31600 but not more resistant
materials, such as annealed duplex stainless steels or higher
4 FIG. 1 Apparatus Used for Stress-Corrosion Cracking Test
nickelalloys,forexample,UNSN08020(forexample20Cb-3
stainless).Thesemoreresistantmaterialsareexpectedtocrack
when exposed to Practice G36 as U-bends. Materials which
S31600) and resistant (for example, UNS N08020) materials
withstand this sodium chloride test for a longer period than
are included in the study.)
UNS S30400 or S31600 may be candidates for more severe
6.1.3 Hot Plate, capable of maintaining the solution at its
service applications.
boiling point.
5.5 The repeatability and reproducibility data from Section
12 and Appendix X1 must be considered prior to use. Inter-
7. Reagents
laboratory variation in results may be expected as occurs with
7.1 Purity of Reagents—Reagent grade chemicals shall be
many corrosion tests. Acceptance criteria are not part of this
used in all tests. Unless otherwise indicated, it is intended that
test method and if needed are to be negotiated by the user and
all reagents shall conform to the specifications of the Commit-
the producer.
tee onAnalytical Reagents of theAmerican Chemical Society,
where such specifications are available. Other grades may be
6. Apparatus
used provided it is first ascertained that the reagent is of
6.1 TheglasswareusedforthistestmethodisshowninFig.
sufficiently high purity to permit its use without affecting
1 and is as follows:
results.
6.1.1 Flask—1000-mL Erlenmeyer flask with a 45/50
7.2 Purity of Water—Solutions shall be made with water of
ground-glass joint.
purityconformingtoatleastTypeIVreagentwaterasspecified
6.1.2 Condenser, a four-bulbAllihn condenser with a 45/50
in Specification D1193 (except that for this method limits for
ground-glass joint (water-cooled joint suggested), a water
chlorides and sodium may be ignored).
jacket at least 20 cm (8 in.) long anda1to2.5cm (0.4 to 0.95
in.) long drip tip is used. (ModifiedAllihn condensers with no
drip tip and condensers with longer drip tips may produce
Reagent Chemicals, American Chemical Society Specifications, American
different results.These alternateAllihn condenser designs may
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
be used if control samples of susceptible (for example, UNS
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
20Cb-3isaregisteredtrademarkofCarpenterTechnologyCorp.,Reading,PA. MD.
G123 – 00 (2005)
7.3 Sodium Chloride (NaCl)—Asolution of 25% NaCl (by 9.5.3 The metallic fastener must be electrically isolated
mass) acidified to pH 1.5 with phosphoric acid (H PO)is from the specimen by a rigid shoulder washer (that is, zirconia
3 4
used.Thesolutionmaybepreparedbyadding750gH O(750 oranothermaterialthatwillnotbecompressedduringthetest).
mL) to 250 g NaCl, and adjusting to pH 1.5 with H PO . 9.5.4 Theextendedendoftheboltmayrequirecuttingtofit
3 4
Varying quantities of solution may be prepared and larger into the test vessel.
amounts may be stored indefinitely in appropriate glassware.
10. Procedure
The pH must be determined prior to each use.
10.1 Stressthespecimens,examineat203,andreplaceany
8. Hazards
specimens with cracks or other defects.
8.1 Normal precautions for handling boiling liquid should
NOTE 2—The direction and intensity of the incident light may affect
be observed.
crack detection during the 203 examination.
8.2 All heating or boiling of the NaCl solution should be
10.2 Degrease in a halogen-free solvent or laboratory deter-
done in an area where personnel are not likely to accidentally
gent,rinseasnecessary,anddry.Itisbestpracticetostressthe
bump the flask. A hooded area is preferred.
specimens immediately before the beginning of the test. Any
8.3 Minimum personal protective equipment for handling
storage of the specimens should be in a clean enclosure. A
boiling sodium chloride should include safety glasses or
desiccant such as silica gel may be used. The specific level of
goggles, face shield, laboratory coat, and rubber gloves.
relative humidity is not important for the alloys of interest.
(Warning—U-bends (and other highly stressed test speci-
10.3 Place duplicate specimens in each 1000-mL Erlenm-
mens) may be susceptible to high rates of crack propagation
eyer flask. Duplicate flasks (four specimens) are necessary to
and a specimen containing more than one crack may splinter
evaluate a given sample of the specific material, material
into two or more pieces. This may also occur due to a cracked
condition,etc.(Thespecimensmaybeplacedintheflasksafter
restraining bolt. Due to the highly stressed condition in a
the solution has been added, if convenient.)
U-bendspecimen,thesepiecesmayleavethespecimenathigh
10.4 The specimens in each flask must be kept separate and
velocity and can be dangerous.)
completely submerged. Tight crevices between the stressed
9. Test Specimens (bend) area and any means of specimen support should be
avoided. The stressed area should be free from direct contact
9.1 U-bends are preferred but other stress corrosion crack-
with heated surfaces. Specimens may be supported on glass
ing specimens may be used with this test solution. The
rods or tubes or by glass fixtures.
specimen style chosen should provide sufficient stress to crack
10.5 Drop boiling chips into the flasks.
less resistant materials (for example, UNS S30400 or S31600)
10.6 Add 600 mL of 25% NaCl solution, pH 1.5, to each
in1000horless).(SeeAnnexA1.)Regardlessofthespecimen
flask. When each flask contains two U-bends as described in
style, it is recommended that UNS S30400 or UNS S31600, or
AnnexA1, the solution volume to sample surface area ratio is
both, be included as controls.
2 2
5:1 mL/cm (33 mL/in. ).
9.2 The test specimen must be thick enough so that the
10.7 Placetheflasksonahotplateandinsertthecondenser.
applied stress does not cause mechanical rupture of less
Begin recording the test duration when the solution begins
resistant materials if the cross section is reduced by pitting or
boiling. The boiling point during interlaboratory testing was
general corrosion.
106 to 110°C (223 to 230°F).
9.3 The size of alternate specimens (other than those in
10.8 After one week remove the flask from the hot plate,
AnnexA1) must allow a solution volume to specimen surface
2 2
determinethefinalpHofthesolutionatroomtemperature,and
area ratio of at least 5:1 mL/cm (33 mL/in. ).
discard the remaining solution. A final pH over about 2.5
9.4 Aminimumoffourreplicates(twoperflask)isrequired
suggests that general corrosion or pitting of the specimen or
because of the variability typical in stress-corrosion testing.
fastening device has occurred.ApH at this level is expected to
9.5 Methods of fabricating U-bend specimens are provided
reduce the test severity and may delay or preclude failures of
inAnnexA1.These procedures are based on Practice G30, but
UNS S31600. More rapid cracking of UNS S31600 appears
in addition provide a specimen that fits through a 45/50
likely with a final pH of about 2 or less.
ground-glass joint. Assurance that the legs are stressed suffi-
10.9 Rinse and dry the specimens. Examine the bend area,
ciently by the bolt is also provided.
legs, and area adjacent to the crevice (at the fastener) at 203
9.5.1 Other methods of producing U-bends described in
forcracking.SeeNote3.Recordlocationofcracks.Additional
Practice G30 may be used; however, during exposure the
exposures or metallographic evaluation may be used to deter-
U-bendsmustbe(1) in the plastic range and (2) stressedtothe
mine if questionable indications are, in fact, stress-corrosion
maximum applied tensile load experienced during fabrication.
cracks.
The same method must be used to fabricate all the U-bends in
a given study.
NOTE 3—Any cracking at the fastener is very likely due to residual
9.5.2 The bolt, nut, and flat washer must be made of a
material resistant to general corrosion, pitting, and stress
The sole source of supply of amphoteric alundum granules known to the
corrosion cracking in the environment. UNS N10276 (Alloy
committee at this time is Hengar Co., Philadelphia, PA. If you are aware of
C-276) is recommended because some other materials (for
alternative suppliers, please provide this information to ASTM International
example, titanium or UNS N06600 [Alloy 600]) may be
Headquarters.Your comments will receive careful consideration at a meeting of the
attacked resulting in an increase in
...
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