ASTM G123-00(2015)

Standard Test Method for Evaluating Stress-Corrosion Cracking of Stainless Alloys with Different Nickel Content in Boiling Acidified Sodium Chloride Solution

SIGNIFICANCE AND USE
5.1 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 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 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 nickel alloys, for example, UNS N08020 (for example 20Cb-34 stainless). These more resistant materials are expected to crack when exposed to Practice G36 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.  
5.5 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 covers 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 (see Section 12) 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 8.

General Information

• Status: Historical
• Publication Date: 31-Oct-2015
• ICS: 77.060 - Corrosion of metals
• Technical Committee: G01 - Corrosion of Metals
• Drafting Committee: G01.06 - Environmentally Assisted Cracking

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:G123 −00 (Reapproved 2015)
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
D1193Specification for Reagent Water
acid. This test method is concerned primarily with the test
E8Test Methods for Tension Testing of Metallic Materials
solutionandglassware,althoughaspecificstyleofU-bendtest
E691Practice 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-
G15TerminologyRelatingtoCorrosionandCorrosionTest-
tion with chemical process industry experience for stainless
ing (Withdrawn 2010)
steels than the more severe boiling magnesium chloride test of
G16Guide for Applying Statistics to Analysis 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
Corrosion Test Specimens
testing(seeSection12)usingthissodiumchloridetestmethod.
G36Practice 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
G49Practice for Preparation and Use of Direct Tension
alloywithuptoabout33%nickel.Itmayalsobeemployedto
Stress-Corrosion Test Specimens
evaluate these types of materials in the cast or welded
G107Guide for Formats for Collection and Compilation of
conditions.
Corrosion Data for Metals for Computerized Database
Input
1.4 This test method detects major effects of composition,
heat treatment, microstructure, and stress on the susceptibility
3. Terminology
of materials to chloride stress-corrosion cracking. Small dif-
ferencesbetweensamplessuchasheat-to-heatvariationsofthe
3.1 Definitions—For definitions of corrosion-related terms
same grade are not likely to be detected.
used in this test method, see Terminology G15.
1.5 The values stated in SI units are to be regarded as the
4. Summary of Test Method
standard. The values given in parentheses are for information
only. 4.1 Asolutionof25%sodiumchloride(by mass)inreagent
water is mixed, and the pH is adjusted to 1.5 with phosphoric
1.6 This standard does not purport to address all of the
acid. The solution is boiled and U-bends (or other stressed
safety concerns, if any, associated with its use. It is the
specimens) are exposed in fresh solution for successive one-
responsibility of the user of this standard to establish appro-
week periods.
priate safety and health practices and determine the applica-
1 2
This test method is under the jurisdiction of ASTM Committee G01 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Corrosion of Metals and is the direct responsibility of Subcommittee G01.06 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Environmentally Assisted Cracking. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2015. Published December 2015. Originally the ASTM website.
approved in 1994. Last previous edition approved in 2011 as G123–00(2011). DOI: The last approved version of this historical standard is referenced on
10.1520/G0123-00R15. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G123−00 (2015)
4.2 The test may be continued for as many weeks as
necessary, but six weeks (about 1000 h) or less are expected to
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
material, for example, UNS S30400 or S31600 (Type 304 or
Type316stainless,respectively),beincludedasacontrolwhen
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.
FIG. 1 Apparatus Used for Stress-Corrosion Cracking Test
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
0.95in.) long drip tip is used. (Modified Allihn condensers
nickelalloys,forexample,UNSN08020(forexample20Cb-3
with no drip tip and condensers with longer drip tips may
stainless).Thesemoreresistantmaterialsareexpectedtocrack
produce different results. These alternate Allihn condenser
when exposed to Practice G36 as U-bends. Materials which
designs may be used if control samples of susceptible (for
withstand this sodium chloride test for a longer period than
example, UNS S31600) and resistant (for example, UNS
UNS S30400 or S31600 may be candidates for more severe
N08020) materials are included in the study.)
service applications.
6.1.3 Hot Plate, capable of maintaining the solution at its
5.5 The repeatability and reproducibility data from Section
boiling point.
12 and Appendix X1 must be considered prior to use. Inter-
laboratory variation in results may be expected as occurs with
7. Reagents
many corrosion tests. Acceptance criteria are not part of this
7.1 Purity of Reagents—Reagent grade chemicals shall be
test method and if needed are to be negotiated by the user and
used in all tests. Unless otherwise indicated, it is intended that
the producer.
all reagents shall conform to the specifications of the Commit-
tee onAnalytical Reagents of theAmerican Chemical Society,
6. Apparatus
where such specifications are available. Other grades may be
6.1 TheglasswareusedforthistestmethodisshowninFig.
used provided it is first ascertained that the reagent is of
1 and is as follows:
sufficiently high purity to permit its use without affecting
6.1.1 Flask—1000-mL Erlenmeyer flask with a 45/50
results.
ground-glass joint.
6.1.2 Condenser, a four-bulbAllihn condenser with a 45/50
Reagent Chemicals, American Chemical Society Specifications, American
ground-glass joint (water-cooled joint suggested), a water
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
jacket at least 20 cm (8 in.) long anda1to2.5cm (0.4 to
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 (2015)
7.2 Purity of Water—Solutions shall be made with water of maximum applied tensile load experienced during fabrication.
purityconformingtoatleastTypeIVreagentwaterasspecified The same method must be used to fabricate all the U-bends in
in Specification D1193 (except that for this method limits for a given study.
chlorides and sodium may be ignored). 9.5.2 The bolt, nut, and flat washer must be made of a
material resistant to general corrosion, pitting, and stress
7.3 Sodium Chloride (NaCl)—Asolution of 25% NaCl (by
corrosion cracking in the environment. UNS N10276 (Alloy
mass) acidified to pH 1.5 with phosphoric acid (H PO)is
3 4
C-276) is recommended because some other materials (for
used. The solution may be prepared by adding 750 g H O
example, titanium or UNS N06600 [Alloy 600]) may be
(750mL) to 250 g NaCl, and adjusting to pH 1.5 with H PO .
3 4
attacked resulting in an increase in solution pH.
Varying quantities of solution may be prepared and larger
9.5.3 The metallic fastener must be electrically isolated
amounts may be stored indefinitely in appropriate glassware.
from the specimen by a rigid shoulder washer (that is, zirconia
The pH must be determined prior to each use.
oranothermaterialthatwillnotbecompressedduringthetest).
9.5.4 Theextendedendoftheboltmayrequirecuttingtofit
8. Hazards
into the test vessel.
8.1 Normal precautions for handling boiling liquid should
10. Procedure
be observed.
10.1 Stress the specimens, examine at 20×, and replace any
8.2 All heating or boiling of the NaCl solution should be
specimens with cracks or other defects.
done in an area where personnel are not likely to accidentally
bump the flask. A hooded area is preferred.
NOTE 2—The direction and intensity of the incident light may affect
crack detection during the 20× examination.
8.3 Minimum personal protective equipment for handling
10.2 Degrease in a halogen-free solvent or laboratory
boiling sodium chloride should include safety glasses or
detergent, rinse as necessary, and dry. It is best practice to
goggles, face shield, laboratory coat, and rubber gloves.
stress the specimens immediately before the beginning of the
(Warning—U-bends (and other highly stressed test speci-
test. Any storage of the specimens should be in a clean
mens) may be susceptible to high rates of crack propagation
enclosure. A desiccant such as silica gel may be used. The
and a specimen containing more than one crack may splinter
specific level of relative humidity is not important for the
into two or more pieces. This may also occur due to a cracked
alloys of interest.
restraining bolt. Due to the highly stressed condition in a
U-bendspecimen,thesepiecesmayleavethespecimenathigh 10.3 Place duplicate specimens in each 1000-mL Erlen-
velocity and can be dangerous.) meyerflask.Duplicateflasks(fourspecimens)arenecessaryto
evaluate a given sample of the specific material, material
9. Test Specimens condition,etc.(Thespecimensmaybeplacedintheflasksafter
the solution has been added, if convenient.)
9.1 U-bends are preferred but other stress corrosion crack-
10.4 The specimens in each flask must be kept separate and
ing specimens may be used with this test solution. The
completely submerged. Tight crevices between the stressed
specimen style chosen should provide sufficient stress to crack
(bend) area and any means of specimen support should be
less resistant materials (for example, UNS S30400 or S31600)
avoided. The stressed area should be free from direct contact
in1000horless).(SeeAnnexA1.)Regardlessofthespecimen
with heated surfaces. Specimens may be supported on glass
style, it is recommended that UNS S30400 or UNS S31600, or
rods or tubes or by glass fixtures.
both, be included as controls.
10.5 Drop boiling chips into the flasks.
9.2 The test specimen must be thick enough so that the
applied stress does not cause mechanical rupture of less 10.6 Add 600 mL of 25% NaCl solution, pH 1.5, to each
resistant materials if the cross section is reduced by pitting or flask. When each flask contains two U-bends as described in
general corrosion. AnnexA1, the solution volume to sample surface area ratio is
2 2
5:1 mL/cm (33 mL/in. ).
9.3 The size of alternate specimens (other than those in
10.7 Placetheflasksonahotplateandinsertthecondenser.
AnnexA1) must allow a solution volume to specimen surface
2 2
Begin recording the test duration when the solution begins
area ratio of at least 5:1 mL/cm (33 mL/in. ).
boiling. The boiling point during interlaboratory testing was
9.4 Aminimumoffourreplicates(twoperflask)isrequired
106 to 110°C (223 to 230°F).
because of the variability typical in stress-corrosion testing.
10.8 After one week remove the flask from the hot plate,
9.5 Methods of fabricating U-bend specimens are provided
determinethefinalpHofthesolutionatroomtemperature,and
inAnnexA1.TheseproceduresarebasedonPracticeG30,but
discard the remaining solution. A final pH over about 2.5
in addition provide a specimen that fits through a 45/50
ground-glass joint. Assurance that the legs are stressed suffi-
ciently by the bolt is also provided. The sole source of supply of amphoteric alundum granules known to the
committee at this time is Hengar Co., Philadelphia, PA. If you are aware of
9.5.1 Other methods of producing U-bends described in
alternative suppliers, please provide this information to ASTM International
Practice G30 may be used; however, during exposure the
Headquarters.Your comments will receive careful consideration at a meeting of the
U-bendsmustbe(1) in the plastic range and (2) stressedtothe responsible technical committee, which you may attend.
G123−00 (2015)
suggests that general corrosion or pitting of the specimen or 12. Precision and Bias
fastening device has occurred.ApH at this level is expected to
12.1 Precision—Variability occurred in both repeatability
reduce the test severity and may delay or preclude failures of
and reproducibility for time-to-fail data developed using UNS
UNS S31600. More rapid cracking of UNS S31600 appears
S30400 and S31600 in an interlaboratory test program (Ap-
likely with a final pH of about 2 or less.
pendix X1). Such variability is typical in time-to-fail data for
10.9 Rinse and dry the specimens.
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: G123 − 00 (Reapproved 2011) G123 − 00 (Reapproved 2015)
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. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers 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 (see Section 12) 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 8.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
E8 Test Methods for Tension Testing of Metallic Materials
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
G15 Terminology Relating to Corrosion and Corrosion Testing (Withdrawn 2010)
G16 Guide for Applying Statistics to Analysis of Corrosion Data
G30 Practice for Making and Using U-Bend Stress-Corrosion Test Specimens
G36 Practice for Evaluating Stress-Corrosion-Cracking Resistance of Metals and Alloys in a Boiling Magnesium Chloride
Solution
G49 Practice for Preparation and Use of Direct Tension Stress-Corrosion Test Specimens
G107 Guide for Formats for Collection and Compilation of Corrosion Data for Metals for Computerized Database Input
3. Terminology
3.1 Definitions—For definitions of corrosion-related terms used in this test method, see Terminology G15.
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 Environmentally
Assisted Cracking.
Current edition approved March 1, 2011Nov. 1, 2015. Published April 2011December 2015. Originally approved in 1994. Last previous edition approved in 20052011
as G123–00(2005).G123–00(2011). DOI: 10.1520/G0123-00R11.10.1520/G0123-00R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G123 − 00 (2015)
4. Summary of Test Method
4.1 A solution of 25 % sodium chloride (by mass) in reagent water is mixed, and the pH is adjusted to 1.5 with phosphoric acid.
The solution is boiled and U-bends (or other stressed specimens) are exposed in fresh solution for successive one-week periods.
4.2 The test may be continued for as many weeks as necessary, but six weeks (about 1000 h) or less are expected to 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 material, 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 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 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 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 nickel alloys, for example, UNS N08020 (for example 20Cb-3 stainless). These more
resistant materials are expected to crack when exposed to Practice G36 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.
5.5 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.
6. Apparatus
6.1 The glassware used for this test method is shown in Fig. 1 and is as follows:
6.1.1 Flask—1000-mL Erlenmeyer flask with a 45/50 ground-glass joint.
6.1.2 Condenser, a four-bulb Allihn condenser with a 45/50 ground-glass joint (water-cooled joint suggested), a water jacket at
least 20 cm (8 in.) long and a 1 to 2.5 cm (0.4 to 0.95 in.) 0.95 in.) long drip tip is used. (Modified Allihn condensers with no drip
tip and condensers with longer drip tips may produce different results. These alternate Allihn condenser designs may be used if
control samples of susceptible (for example, UNS S31600) and resistant (for example, UNS N08020) materials are included in the
study.)
6.1.3 Hot Plate, capable of maintaining the solution at its boiling point.
7. Reagents
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without affecting results.
7.2 Purity of Water—Solutions shall be made with water of purity conforming to at least Type IV reagent water as specified in
Specification D1193 (except that for this method limits for chlorides and sodium may be ignored).
7.3 Sodium Chloride (NaCl)—A solution of 25 % NaCl (by mass) acidified to pH 1.5 with phosphoric acid (H PO ) is used.
3 4
The solution may be prepared by adding 750 g H O (750 mL) (750 mL) to 250 g NaCl, and adjusting to pH 1.5 with H PO .
2 3 4
Varying quantities of solution may be prepared and larger amounts may be stored indefinitely in appropriate glassware. The pH
must be determined prior to each use.
8. Hazards
8.1 Normal precautions for handling boiling liquid should be observed.
20Cb-3 is a registered trademark of Carpenter Technology Corp., Reading, PA.
Reagent Chemicals, American Chemical Society Specifications, American 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, MD.
G123 − 00 (2015)
FIG. 1 Apparatus Used for Stress-Corrosion Cracking Test
8.2 All heating or boiling of the NaCl solution should be done in an area where personnel are not likely to accidentally bump
the flask. A hooded area is preferred.
8.3 Minimum personal protective equipment for handling boiling sodium chloride should include safety glasses or goggles, face
shield, laboratory coat, and rubber gloves. (Warning—U-bends (and other highly stressed test specimens) may be susceptible to
high rates of crack propagation and a specimen containing more than one crack may splinter into two or more pieces. This may
also occur due to a cracked restraining bolt. Due to the highly stressed condition in a U-bend specimen, these pieces may leave
the specimen at high velocity and can be dangerous.)
9. Test Specimens
9.1 U-bends are preferred but other stress corrosion cracking specimens may be used with this test solution. The specimen style
chosen should provide sufficient stress to crack less resistant materials (for example, UNS S30400 or S31600) in 1000 h or less).
(See Annex A1.) Regardless of the specimen style, it is recommended that UNS S30400 or UNS S31600, or both, be included as
controls.
9.2 The test specimen must be thick enough so that the applied stress does not cause mechanical rupture of less resistant
materials if the cross section is reduced by pitting or general corrosion.
9.3 The size of alternate specimens (other than those in Annex A1) must allow a solution volume to specimen surface area ratio
2 2
of at least 5:1 mL/cm (33 mL/in. ).
9.4 A minimum of four replicates (two per flask) is required because of the variability typical in stress-corrosion testing.
9.5 Methods of fabricating U-bend specimens are provided in Annex A1. These procedures are based on Practice G30, but in
addition provide a specimen that fits through a 45/50 ground-glass joint. Assurance that the legs are stressed sufficiently by the bolt
is also provided.
9.5.1 Other methods of producing U-bends described in Practice G30 may be used; however, during exposure the U-bends must
be (1) in the plastic range and (2) stressed to the maximum applied tensile load experienced during fabrication. The same method
must be used to fabricate all the U-bends in a given study.
G123 − 00 (2015)
9.5.2 The bolt, nut, and flat washer must be made of a material resistant to general corrosion, pitting, and stress 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 attacked resulting in an increase in solution pH.
9.5.3 The metallic fastener must be electrically isolated from the specimen by a rigid shoulder washer (that is, zirconia or
another material that will not be compressed during the test).
9.5.4 The extended end of the bolt may require cutting to fit into the test vessel.
10. Procedure
10.1 Stress the specimens, examine at 20×, and replace any specimens with cracks or other defects.
NOTE 2—The direction and intensity of the incident light may affect crack detection during the 20× examination.
10.2 Degrease in a halogen-free solvent or laboratory detergent, rinse as necessary, and dry. It is best practice to stress the
specimens immediately before the beginning of the test. Any storage of the specimens should be in a clean enclosure. A desiccant
such as silica gel may be used. The specific level of relative humidity is not important for the alloys of interest.
10.3 Place duplicate specimens in each 1000-mL Erlenmeyer flask. Duplicate flasks (four specimens) are necessary to evaluate
a given sample of the specific material, material condition, etc. (The specimens may be placed in the flasks after the solution has
been added, if convenient.)
10.4 The specimens in each flask must be kept separate and completely submerged. Tight crevices between the stressed (bend)
area and any means of specimen support should be avoided. The stressed area should be free from direct contact with heated
surfaces. Specimens may be supported on glass rods or tubes or by glass fixtures.
10.5 Drop boiling chips into the flasks.
10.6 Add 600 mL of 25 % NaCl solution, pH 1.5, to each flask. When each flask contains two U-bends as described in Annex
2 2
A1, the solution volume to sample surface area ratio is 5:1 mL/cm (33 mL/in. ).
10.7 Place the flasks on a hot plate and insert the condenser. Begin recording the test duration when the solution begins boiling.
The boiling point during interlaboratory testing was 106 to 110°C (223 to 230°F).
10.8 After one week remove the flask from the hot plate, determine the final pH of the solution at room temperature, and discard
the remaining solution. A final pH over about 2.5 suggests that general corrosion or pitting of the specimen or fastening device
has occurred. A pH at this level is expected to reduce the test severity and may delay or preclude failures of UNS S31600. More
rapid cracking of UNS S31600 appears likely with a final pH of about 2 or less.
10.9 Rinse and dry the specimens. E
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