ASTM G36-94(2013)
(Practice)Standard Practice for Evaluating Stress-Corrosion-Cracking Resistance of Metals and Alloys in a Boiling Magnesium Chloride Solution
Standard Practice for Evaluating Stress-Corrosion-Cracking Resistance of Metals and Alloys in a Boiling Magnesium Chloride Solution
SIGNIFICANCE AND USE
5.1 For most applications, this environment provides an accelerated method of ranking the relative degree of stress-corrosion cracking susceptibility for stainless steels and related alloys in aqueous chloride-containing environments. Materials that normally provide acceptable resistance in hot chloride service may crack in this test. The test may not be relevant to stress-corrosion cracking in polythionic acid or caustic environments.
5.2 Resistance to stress-corrosion cracking in boiling magnesium chloride (155.0°C (311.0°F)) should, where possible, be correlated to resistance in service for the materials of interest. However, such correlations may not always be possible.
5.3 Boiling magnesium chloride may also cause pitting of many stainless alloys. This leads to the possibility of confusing stress-corrosion failures with mechanical failures induced by corrosion-reduced net cross sections. This danger is particularly great when small cross section samples, high applied stress levels, long exposure periods, stress-corrosion resistant alloys, or a combination thereof are being used. Careful examination is recommended for correct diagnosis of the cause of failure.
SCOPE
1.1 This practice describes a procedure for conducting stress-corrosion cracking tests in a boiling magnesium chloride solution. Although this test may be performed using various concentrations of magnesium chloride, this procedure covers a test solution held at a constant boiling temperature of 155.0 ± 1.0°C (311.0 ± 1.8°F). The boiling points of aqueous magnesium chloride solutions at one atmosphere pressure as a function of concentration are shown graphically in Fig. 1.2 A suggested test apparatus capable of maintaining solution concentration and temperature within the prescribed limits for extended periods of time is also described herein.3
1.2 The boiling magnesium chloride test is applicable to wrought, cast, and welded stainless steels and related alloys. It is a method for detecting the effects of composition, heat treatment, surface finish, microstructure, and stress on the susceptibility of these materials to chloride stress corrosion cracking.4
1.3 This practice is concerned primarily with the test solution, which may be used with a variety of stress corrosion test specimens, surface finishes, and methods of applying stress.
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 Section 7 for specific safety precautions.
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Standards Content (Sample)
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Designation: G36 − 94 (Reapproved 2013)
Standard Practice for
Evaluating Stress-Corrosion-Cracking Resistance of Metals
and Alloys in a Boiling Magnesium Chloride Solution
ThisstandardisissuedunderthefixeddesignationG36;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. See Section 7 for
1.1 This practice describes a procedure for conducting
specific safety precautions.
stress-corrosioncrackingtestsinaboilingmagnesiumchloride
solution. Although this test may be performed using various
2. Referenced Documents
concentrations of magnesium chloride, this procedure covers a
2.1 ASTM Standards:
test solution held at a constant boiling temperature of 155.0 6
D1193Specification for Reagent Water
1.0°C (311.0 6 1.8°F). The boiling points of aqueous magne-
G1Practice for Preparing, Cleaning, and Evaluating Corro-
sium chloride solutions at one atmosphere pressure as a
sion Test Specimens
function of concentration are shown graphically in Fig. 1. A
G15Terminology Relating to Corrosion and CorrosionTest-
suggested test apparatus capable of maintaining solution con-
ing (Withdrawn 2010)
centration and temperature within the prescribed limits for
G30 Practice for Making and Using U-Bend Stress-
extended periods of time is also described herein.
Corrosion Test Specimens
1.2 The boiling magnesium chloride test is applicable to
3. Terminology
wrought, cast, and welded stainless steels and related alloys. It
is a method for detecting the effects of composition, heat
3.1 Definitions—For definitions of terms used in this prac-
treatment, surface finish, microstructure, and stress on the
tice see Terminology G15.
susceptibility of these materials to chloride stress corrosion
4 4. Summary of Practice
cracking.
4.1 A predetermined quantity of reagent grade magnesium
1.3 This practice is concerned primarily with the test
chloride and some distilled water are added to a container.The
solution, which may be used with a variety of stress corrosion
container and contents, with thermometer and condenser
test specimens, surface finishes, and methods of applying
affixed, are placed on a source of heat. When the magnesium
stress.
chloride solution boils, it is adjusted to maintain the desired
1.4 This standard does not purport to address all of the
concentration and boiling point through the addition of small
safety concerns, if any, associated with its use. It is the
quantities of either water or salt.
responsibility of the user of this standard to establish appro-
4.2 After the solution has stabilized at the desired boiling
pointforthetest,thestressedspecimensareadded.Depending
This practice is under the jurisdiction ofASTM Committee G01 on Corrosion
upon the intent of the test, the specimens should be given
of Metals and is the direct responsibility of Subcommittee G01.06 on Environmen-
periodic inspections. If the duration of test exceeds 7 days, the
tally Assisted Cracking.
solution should either be changed or the suggested or similar
CurrenteditionapprovedMay1,2013.PublishedJuly2013.Originallyapproved
in 1973. Last previous edition approved in 2006 as G36–94 (2006). DOI:
test apparatus used.
10.1520/G0036-94R13.
Available data on the relationship of concentrations and boiling points of
5. Significance and Use
magnesium chloride solutions are critically reviewed and supplemented by I. B.
5.1 For most applications, this environment provides an
Casale in “Boiling Points of Magnesium Chloride Solutions—TheirApplication in
Stress Corrosion Studies,” Corrosion , Vol 23, 1967, pp. 314–17.
accelerated method of ranking the relative degree of stress-
The apparatus and test procedures for maintaining constant boiling tempera-
corrosioncrackingsusceptibilityforstainlesssteelsandrelated
tures of magnesium chloride solutions for stress corrosion tests are described by M.
A. Streicher and A. J. Sweet in Corrosion, Vol 25, 1969, pp. 1–6.
4 5
The use of concentrated magnesium chloride solutions for determining the For referenced ASTM standards, visit the ASTM website, www.astm.org, or
susceptibility to stress corrosion cracking of austenitic and ferritic stainless steels contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
and related nickel-base alloys was first described by M. A. Scheil, Symposium on Standards volume information, refer to the standard’s Document Summary page on
Stress Corrosion Cracking of Metals, ASTM STP 64, ASTM, 1945, p. 395. the ASTM website.
(Although currently out of print, copies may be obtained from University Micro- The last approved version of this historical standard is referenced on
films, Inc., 300 North Zeeb Rd., Ann Arbor, MI 48106.) www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G36 − 94 (2013)
stresscorrosioncracking.Asuggestedapparatus,showninFig.
X1.1, meets these requirements. Design details of this appara-
tus are given in Appendix X1.
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 Commit-
tee onAnalytical Reagents of theAmerican 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 lessening the
accuracy of the determination.
7.2 Purity of Water—Reagent water Type IV (Specification
D1193) shall be used to prepare the test solutions.
7.3 Magnesium Chloride(MgCl ·6H O)—A solution of
2 2
magnesium chloride that boils at 155.0 6 1.0°C (311.0 6
1.8°F) is used in this test.Asecond 25 weight percent solution
of magnesium chloride is required for the trap if the test
duration exceeds seven days without a solution change and the
suggested apparatus is used.
7.3.1 Toprepareabout400mLofthetestsolutionforusein
a 1-L Erlenmeyer flask or other container, weigh 600 g of
reagentgradeMgCl ·6H Oandaddthistotheflaskcontaining
2 2
FIG. 1 Boiling Points of Aqueous Magnesium Chloride Solutions
a thermometer along with 15 mL of reagent water.
at One Atmosphere as a Function of Concentration
7.3.2 Add 10 to 15 boiling chips or other boiling aids.
7.3.3 Heat by placing the flask on a hot plate or other
suitable source of heat and put the condenser in place, leaving
alloys in aqueous chloride-containing environments. Materials
offthetrap.Hookupthecoolingwatersupplytothecondenser.
that normally provide acceptable resistance in hot chloride
7.3.4 When the solution boils vigorously and there is no
service may crack in this test. The test may not be relevant to
more dripping of condensate, slowly add small quantities (4 to
stress-corrosion cracking in polythionic acid or caustic envi-
5mL)ofreagentwateratthetopofthecondensertoreducethe
ronments.
temperature to 155.0°C (311.0°F). Use extreme caution when
5.2 Resistance to stress-corrosion cracking in boiling mag-
adding the water to the boiling magnesium chloride solution.
nesium chloride (155.0°C (311.0°F)) should, where possible,
Coolwatercanformalayerontopofthemagnesiumchloride,
be correlated to resistance in service for the materials of
andwhenitreachesthebottomoftheflask,bumpingcanoccur.
interest. However, such correlations may not always be pos-
Use a protective shield.
sible.
NOTE 1—If too much water has been added, add some crystals of
5.3 Boiling magnesium chloride may also cause pitting of
MgCl ·6H O through the condenser until a temperature of 155.0°C
2 2
manystainlessalloys.Thisleadstothepossibilityofconfusing
(311.0°F) is attained.
stress-corrosion failures with mechanical failures induced by
7.4 To prepare the 25 weight percent solution for the trap
corrosion-reduced net cross sections. This danger is particu-
(Fig. X1.3), place 53.4 g of MgCl ·6H O and 46.6 mL of
2 2
larly great when small cross section samples, high applied
reagent water in a flask and allow the crystals to dissolve at
stress levels, long exposure periods, stress-corrosion resistant
room temperature.
alloys, or a combination thereof are being used. Careful
examinationisrecommendedforcorrectdiagnosisofthecause
8. Safety Precautions
of failure.
8.1 When cold, magnesium chloride can be handled with
the minimum protective equipment of rubber gloves and
6. Apparatus
goggles. Maximum protective measures should be taken to
6.1 Any inert, transparent apparatus with provisions for a
prevent boiling magnesium chloride from coming into contact
thermometer and water-cooled condenser can be used, pro-
with the skin. Severe burns can result as the hot magnesium
videdthatithasbeendesignedtocontainthestressedspecimen
while maintaining a constant temperature and concentration of
the magnesium chloride solution by minimizing or preventing
Reagent Chemicals, American Chemical Society Specifications , American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
lossesofcondensateandwatervaporduringprolongedperiods
listed by the American Chemical Society, see Analar Standards for Laboratory
of test. Small losses of water from a solution of magnesium
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
chloride will lead to large increases in the boiling point of the
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
solutionwithareductioninthetimetofailureofaspecimenby MD.
G36 − 94 (2013)
chloride adheres to the skin forming a crust which causes deep rods or tubes. The design for two types of test specimens that
burns. The severity of the burns can be reduced by taking can be used with the suggested apparatus can be found in
proper and immediate first aid measures and by contacting a footnote 3.
physician.
10. Procedure
8.1.1 Intheadventofaspilloraccident, the hot magnesium
10.1 Collecttheapparatusandtestspecimensinpreparation
chloride should be quickly flushed from the skin with large
for the test. If the suggested test apparatus is used, assemble as
quantities of cold water to minimize the burning, followed by
outlined in Appendix X1.
immediate first aid and medical attention.
8.1.2 All heating or boiling of magnesium chloride should
10.2 Preparethetestsolutionbyaddingaknownquantityof
bedoneinashieldedareawithprotectionbyhoodorshield,or reagent grade MgCl ·6H O, reagent water, and some boiling
2 2
both.
aids to the container fitted with a thermometer and water-
8.1.3 Minimum personal protective equipment for handling cooledcondenser.Afterapplyingheat,adjusttheconcentration
boiling magne
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