ASTM G123-00
(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
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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Designation: G 123 – 00
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method describes a procedure for conducting 2.1 ASTM Standards:
stress-corrosion cracking tests in an acidified boiling sodium D1193 Specification for Reagent Water
chloride solution. This test method is performed in 25% (by E8 TestMethodsforTensionTestingofMetallicMaterials
mass) sodium chloride acidified to pH 1.5 with phosphoric E691 Practice for Conducting an Interlaboratory Study to
acid. This test method is concerned primarily with the test Determine the Precision of a Test Method
solutionandglassware,althoughaspecificstyleofU-bendtest G15 Terminology Relating to Corrosion and Corrosion
specimen is suggested. Testing
1.2 This test method is designed to provide better correla- G16 GuideforApplyingStatisticstoAnalysisofCorrosion
tion with chemical process industry experience for stainless Data
steels than the more severe boiling magnesium chloride test of G30 Practice for Making and Using U-Bend Stress Corro-
Practice G36. Some stainless steels which have provided sion Test Specimens
satisfactory service in many environments readily crack in G36 Practice for Evaluating Stress-Corrosion-Cracking
Practice G36, but have not cracked during interlaboratory Resistance of Metals and Alloys in a Boiling Magnesium
testing using this sodium chloride test method. Chloride Solution
1.3 Thisboilingsodiumchloridetestmethodwasusedinan G49 Practice for Preparation and Use of Direct Tension
interlaboratory test program to evaluate wrought stainless Stress Corrosion Test Specimens
steels, including duplex (ferrite-austenite) stainless and an G107 GuideforFormatsforCollectionandCompilationof
alloywithuptoabout33%nickel.Itmayalsobeemployedto Corrosion Data for Metals for Computerized Database
evaluate these types of materials in the cast or welded Input
conditions.
3. Terminology
1.4 This test method detects major effects of composition,
heat treatment, microstructure, and stress on the susceptibility 3.1 Definitions:
3.1.1 For definitions of corrosion-related terms used in this
of materials to chloride stress-corrosion cracking. Small dif-
ferencesbetweensamplessuchasheat-to-heatvariationsofthe test method, see Terminology G15.
same grade are not likely to be detected.
4. Summary of Test Method
1.5 The values stated in SI units are to be regarded as the
4.1 Asolutionof25%sodiumchloride(by mass)inreagent
standard. The values given in parentheses are for information
water is mixed, and the pH is adjusted to 1.5 with phosphoric
only.
acid. The solution is boiled and U-bends (or other stressed
1.6 This standard does not purport to address all of the
specimens) are exposed in fresh solution for successive one-
safety concerns, if any, associated with its use. It is the
week periods.
responsibility of the user of this standard to establish appro-
4.2 The test may be continued for as many weeks as
priate safety and health practices and determine the applica-
necessary, but six weeks (about 1000 h) or less are expected to
bility of regulatory limitations prior to use. For specific hazard
be sufficient to crack susceptible materials. Longer exposures
statements, see Section 7 .
provide greater assurance of resistance for those materials
which do not crack.
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
Stress Corrosion Cracking and Corrosion Fatigue.
Current edition approved Oct. 10, 2000. Published October 2000. Originally Annual Book of ASTM Standards, Vol 11.01.
published as G123–94. Last previous edition G123–96. Annual Book of ASTM Standards, Vol 03.01.
2 5
Interlaboratory test program including UNS S30400, S31600, S32550, and Annual Book of ASTM Standards, Vol 14.02.
N08020. These data are available at ASTM Headquarters. Request RR G01-1013. Annual Book of ASTM Standards, Vol 03.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G123–00
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
thantheboilingmagnesiumchloridetestofPracticeG36.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
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.
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
nickelalloys,forexample,UNSN08020(forexample20Cb-3
stainless).These more resistant materials are expected to crack
when exposed to Practice G36 as U-bends. Materials which
FIG. 1 Apparatus Used for Stress-Corrosion Cracking Test
withstand this sodium chloride test for a longer period than
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
11 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
7.3 Sodium Chloride (NaCl)—Asolution of 25% NaCl (by
in.) long drip tip is used. (ModifiedAllihn condensers with no
mass) acidified to pH 1.5 with phosphoric acid (H PO)is
3 4
drip tip and condensers with longer drip tips may produce
used.Thesolutionmaybepreparedbyadding750gH O(750
different results.These alternateAllihn condenser designs may
be used if control samples of susceptible (for example, UNS
S31600) and resistant (for example, UNS N08020) materials
Reagent Chemicals, American Chemical Society Specifications, American
are included in the study.)
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
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-3 is a registered trademark of CarpenterTechnology Corp., Reading, PA. MD.
G123–00
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.
The pH must be determined prior to each use. 10. Procedure
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
bump the flask. A hooded area is preferred. gent, rinse as necessary, and dry. It is best practice to stress the
specimens immediately before the beginning of the test. Any
8.3 Minimum personal protective equipment for handling
boiling sodium chloride should include safety glasses or storage of the specimens should be in a clean enclosure. A
desiccant such as silica gel may be used. The specific level of
goggles, face shield, laboratory coat, and rubber gloves.
(Warning—U-bends (and other highly stressed test speci- relative humidity is not important for the alloys of interest.
10.3 Place duplicate specimens in each 1000-mL Erlenm-
mens) may be susceptible to high rates of crack propagation
and a specimen containing more than one crack may splinter eyer flask. Duplicate flasks (four specimens) are necessary to
evaluate a given sample of the specific material, material
into two or more pieces. This may also occur due to a cracked
restraining bolt. Due to the highly stressed condition in a condition,etc.(Thespecimensmaybeplacedintheflasksafter
the solution has been added, if convenient.)
U-bendspecimen,thesepiecesmayleavethespecimenathigh
velocity and can be dangerous.) 10.4 The specimens in each flask must be kept separate and
completely submerged. Tight crevices between the stressed
9. Test Specimens
(bend) area and any means of specimen support should be
9.1 U-bends are preferred but other stress corrosion crack- avoided. The stressed area should be free from direct contact
ing specimens may be used with this test solution. The with heated surfaces. Specimens may be supported on glass
specimen style chosen should provide sufficient stress to crack rods or tubes or by glass fixtures.
less resistant materials (for example, UNS S30400 or S31600) 10.5 Drop boiling chips into the flasks.
in1000horless).(SeeAnnexA1.)Regardlessofthespecimen
10.6 Add 600 mL of 25% NaCl solution, pH 1.5 to each
style, it is recommended that UNS S30400 or UNS S31600, or flask. When each flask contains two U-bends as described in
both, be included as controls.
AnnexA1, the solution volume to sample surface area ratio is
2 2
9.2 The test specimen must be thick enough so that the 5:1 mL/cm (33 mL/in ).
applied stress does not cause mechanical rupture of less
10.7 Placetheflasksonahotplateandinsertthecondenser.
resistant materials if the cross section is reduced by pitting or Begin recording the test duration when the solution begins
general corrosion.
boiling. The boiling point during interlaboratory testing was
9.3 The size of alternate specimens (other than those in 106 to 110°C (223 to 230°F).
AnnexA1) must allow a solution volume to specimen surface
10.8 After one week remove the flask from the hot plate,
2 2
area ratio of at least 5:1 mL/cm (33 mL/in. ). determinethefinalpHofthesolutionatroomtemperature,and
9.4 Aminimumoffourreplicates(twoperflask)isrequired
discard the remaining solution. A final pH over about 2.5
because of the variability typical in stress-corrosion testing. suggests that general corrosion or pitting of the specimen or
9.5 Methods of fabricating U-bend specimens are provided
fastening device has occurred.ApH at this level is expected to
inAnnexA1.TheseproceduresarebasedonPracticeG30,but reduce the test severity and may delay or preclude failures of
in addition provide a specimen that fits through a 45/50 UNS S31600. More rapid cracking of UNS S31600 appears
ground-glass joint. Assurance that the legs are stressed suffi- likely with a final pH of about 2 or less.
ciently by the bolt is also provided. 10.9 Rinse and dry the specimens. Examine the bend area,
9.5.1 Other methods of producing U-bends described in legs, and area adjacent to the crevice (at the fastener) at 203
Practice G30 may be used; however, during exposure the forcracking.SeeNote3.Recordlocationofcracks.Additional
U-bends must be (a) in the plastic range and (b) stressed to the
exposures or metallographic evaluation may be used to deter-
maximum applied tensile load experienced during fabrication. mine if questionable indications are, in fact, stress-corrosion
The same methodmust be used to fabricate all the U-bends in
cracks.
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
stressesandmoreaggressivesolutionwhichmaybeformedincrevices.If
material resistant to general corrosion, pitting, and stress
crevices are expected in service (due to design of service equipment or
corrosion cracking in the environment. UNS N10276 (Alloy
C-276) is recommended because some other materials (for
example, titanium or UNS N06600 [Alloy 600]) may be
The sole source of supply of amphoteric alundum granules known to the
attacked resulting in an increase in solution pH.
committee at this time is Hengar Co., Philadelphia, PA. If you are aware of
9.5.3 The metallic fastener must be electrically isolated
alternative suppliers, please provide this information toASTM Headquarters. Your
fromthespecimenbyarigidshoulderwasher,(thatis,zirconia
comments will receive careful consideration at a meeting of the responsible
oranothermaterialthatwillnotbecompressedduringthetest).
...
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