ASTM G37-98(2016)

Standard Practice for Use of Mattsson's Solution of pH 7.2 to Evaluate the Stress-Corrosion Cracking Susceptibility of Copper-Zinc Alloys

SIGNIFICANCE AND USE
4.1 This test environment is believed to give an accelerated ranking of the relative or absolute degree of stress-corrosion cracking susceptibility for different brasses. It has been found to correlate well with the corresponding service ranking in environments that cause stress-corrosion cracking which is thought to be due to the combined presence of traces of moisture and ammonia vapor. The extent to which the accelerated ranking correlates with the ranking obtained after long-term exposure to environments containing corrodents other than ammonia is not at present known. Examples of such environments may be severe marine atmospheres (Cl−), severe industrial atmospheres (predominantly SO2), and super-heated ammonia-free steam.  
4.2 It is not possible at present to specify any particular time to failure (defined on the basis of any particular failure criteria) in pH 7.2 Mattsson's solution that corresponds to a distinction between acceptable and unacceptable stress-corrosion behavior in brass alloys. Such particular correlations must be determined individually.  
4.3 Mattsson's solution of pH 7.2 may also cause stress independent general and intergranular corrosion of brasses to some extent. 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 with small cross section specimens, high applied stress levels, long exposure periods and stress-corrosion resistant alloys. Careful metallographic examination is recommended for correct diagnosis of the cause of failure. Alternatively, unstressed control specimens may be exposed to evaluate the extent to which stress independent corrosion degrades mechanical properties.
SCOPE
1.1 This practice covers the preparation and use of Mattsson's solution of pH 7.2 as an accelerated stress-corrosion cracking test environment for brasses (copper-zinc base alloys). The variables (to the extent that these are known at present) that require control are described together with possible means for controlling and standardizing these variables.  
1.2 This practice is recommended only for brasses (copper-zinc base alloys). The use of this test environment is not recommended for other copper alloys since the results may be erroneous, providing completely misleading rankings. This is particularly true of alloys containing aluminum or nickel as deliberate alloying additions.  
1.3 This practice is intended primarily where the test objective is to determine the relative stress-corrosion cracking susceptibility of different brasses under the same or different stress conditions or to determine the absolute degree of stress corrosion cracking susceptibility, if any, of a particular brass or brass component under one or more specific stress conditions. Other legitimate test objectives for which this test solution may be used do, of course, exist. The tensile stresses present may be known or unknown, applied or residual. The practice may be applied to wrought brass products or components, brass castings, brass weldments, and so forth, and to all brasses. Strict environmental test conditions are stipulated for maximum assurance that apparent variations in stress-corrosion susceptibility are attributable to real variations in the material being tested or in the tensile stress level and not to environmental variations.  
1.4 This practice relates solely to the preparation and control of the test environment. No attempt is made to recommend surface preparation or finish, or both, as this may vary with the test objectives. Similarly, no attempt is made to recommend particular stress-corrosion test specimen configurations or methods of applying the stress. Test specimen configurations that may be used are referenced in Practice G30 and STP 425.2  
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included ...

General Information

• Status: Historical
• Publication Date: 30-Apr-2016
• ICS: 77.060 - Corrosion of metals
• ICS: 77.120.30 - Copper and copper alloys
• 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: G37 − 98 (Reapproved 2016)
Standard Practice for
Use of Mattsson’s Solution of pH 7.2 to Evaluate the Stress-
Corrosion Cracking Susceptibility of Copper-Zinc Alloys
ThisstandardisissuedunderthefixeddesignationG37;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope rations or methods of applying the stress. Test specimen
configurations that may be used are referenced in PracticeG30
1.1 This practice covers the preparation and use of Matts-
and STP425.
son’s solution of pH 7.2 as an accelerated stress-corrosion
1.5 The values stated in SI units are to be regarded as
cracking test environment for brasses (copper-zinc base al-
standard. No other units of measurement are included in this
loys). The variables (to the extent that these are known at
standard.
present) that require control are described together with pos-
sible means for controlling and standardizing these variables.
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.2 This practice is recommended only for brasses (copper-
responsibility of the user of this standard to establish appro-
zinc base alloys). The use of this test environment is not
priate safety and health practices and determine the applica-
recommended for other copper alloys since the results may be
bility of regulatory limitations prior to use. (For more specific
erroneous, providing completely misleading rankings. This is
safety hazard statements see Section 8.)
particularly true of alloys containing aluminum or nickel as
deliberate alloying additions.
2. Referenced Documents
1.3 This practice is intended primarily where the test objec-
2.1 ASTM Standards:
tive is to determine the relative stress-corrosion cracking
D1193Specification for Reagent Water
susceptibility of different brasses under the same or different
G30 Practice for Making and Using U-Bend Stress-
stress conditions or to determine the absolute degree of stress
Corrosion Test Specimens
corrosioncrackingsusceptibility,ifany,ofaparticularbrassor
brass component under one or more specific stress conditions.
3. Summary of Practice
Otherlegitimatetestobjectivesforwhichthistestsolutionmay
3.1 The practice consists of completely and continuously
beuseddo,ofcourse,exist.Thetensilestressespresentmaybe
immersing a stressed test specimen in an aqueous solution
known or unknown, applied or residual. The practice may be
++ +
containing 0.05 g-atom/L of Cu and 1 g-mol/L of NH and
applied to wrought brass products or components, brass
+
of pH 7.2. The copper is added as CuSO ·5H O and the NH
4 2 4
castings, brass weldments, and so forth, and to all brasses.
as a mixture of NH OH and (NH ) SO . The ratio of these
4 4 2 4
Strict environmental test conditions are stipulated for maxi-
latter two compounds is adjusted to give the desired pH.
mum assurance that apparent variations in stress-corrosion
Exposure time, criterion of failure, and so forth, are variable
susceptibility are attributable to real variations in the material
and not specifically recommended.
being tested or in the tensile stress level and not to environ-
mental variations.
4. Significance and Use
1.4 This practice relates solely to the preparation and
4.1 This test environment is believed to give an accelerated
control of the test environment. No attempt is made to
ranking of the relative or absolute degree of stress-corrosion
recommend surface preparation or finish, or both, as this may
cracking susceptibility for different brasses. It has been found
vary with the test objectives. Similarly, no attempt is made to
to correlate well with the corresponding service ranking in
recommend particular stress-corrosion test specimen configu-
environments that cause stress-corrosion cracking which is
thought to be due to the combined presence of traces of
This practice is under the jurisdiction ofASTM Committee G01 on Corrosion
of Metals and is the direct responsibility of Subcommittee G01.06 on Environmen- STP425, Stress Corrosion Testing, ASTM International.
tally Assisted Cracking. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2016. Published May 2016. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approvedin1973.Lastpreviouseditionapprovedin2011asG37–98(2011).DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/G0037-98R16. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G37 − 98 (2016)
moisture and ammonia vapor. The extent to which the accel- Committee on Analytical Reagents of the American Chemical
erated ranking correlates with the ranking obtained after Society shall be used.
long-term exposure to environments containing corrodents
6.2 Purity of Water—Reagent water Type IV (Specification
otherthanammoniaisnotatpresentknown.Examplesofsuch
D1193) shall be used to prepare the test solution.
−
environments may be severe marine atmospheres (Cl ), severe
industrial atmospheres (predominantly SO ), and super-heated 7. Test Solution
ammonia-free steam.
7.1 The concentration of the test solution shall be 0.05
++
g-atom/Lwith respect to Cu and 1.0 g-mol/Lwith respect to
4.2 Itisnotpossibleatpresenttospecifyanyparticulartime
+
tofailure(definedonthebasisofanyparticularfailurecriteria) NH . The pH of the test solution shall be 7.2+0.3,−0.1 pH.
in pH 7.2 Mattsson’s solution that corresponds to a distinction
7.2 The test solution shall be prepared by completely
betweenacceptableandunacceptablestress-corrosionbehavior
dissolving 590.0 6 1.0 g of (NH ) SO in 4 Lof water and by
4 2 4
inbrassalloys.Suchparticularcorrelationsmustbedetermined
completely dissolving 125.0 6 0.5 g of CuSO ·5HOin1Lof
4 2
individually.
water. These two solutions should then be thoroughly mixed
and 71.0 6 0.2 mLof NH OH solution added, preferably with
4.3 Mattsson’s solution of pH 7.2 may also cause stress 4
a buret. Finally, the whole should be diluted to 10.0 6 0.1 L
independent general and intergranular corrosion of brasses to
and allowed to age for 48 to 96 h in the test container prior to
some extent. This leads to the possibility of confusing stress-
use. It is not recommended that the solution be stored for
corrosion failures with mechanical failures induced by
extended periods or used without the specified aging. Smaller
corrosion-reduced net cross sections. This danger is particu-
or larger volumes of solution can be prepared using lesser
larly great with small cross section specimens, high applied
amounts of reagents in the same proportions.
stress levels, long exposure periods and stress-corrosion resis-
tant alloys. Careful metallographic examination is recom-
7.3 After aging, the pH of the test solution should be
mended for correct diagnosis of the cause of failure.
measured. If outside the range specified above, the pH may be
Alternatively, unstressed control specimens may be exposed to
adjusted to within the range 7.1 to 7.5 by the addition of fresh
evaluate the extent to which stress independent corrosion
pH 4 or pH 10 Mattsson’s solution. Addition of NH OH or
degrades mechanical properties.
H SO to adjust pH is not recommended since the concentra-
2 4
tion of the various soluble ions can be considerably altered.
5. Apparatus
7.4 Temperature control of the test solution is not recom-
5.1 Anysuitableinertcontainermaybeusedtoholdthetest
mended.Instead,theroomairtemperatureshouldbecontrolled
solutionandtestspecimensduringexposure.Glassorplasticis at 21 6 3°C and the test solution allowed to reach its
highly recommended. The container should be fitted with a
equilibrium temperature with the air. No room air relative
removable top to reduce evaporation during test, thus prevent- humiditycontrolisrecommendedandtemperaturerecordingis
ing dust and other particulate matter from entering the
not mandatory.
environment, a
...

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: G37 − 98 (Reapproved 2011) G37 − 98 (Reapproved 2016)
Standard Practice for
Use of Mattsson’s Solution of pH 7.2 to Evaluate the Stress-
Corrosion Cracking Susceptibility of Copper-Zinc Alloys
This standard is issued under the fixed designation G37; 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 practice covers the preparation and use of Mattsson’s solution of pH 7.2 as an accelerated stress-corrosion cracking
test environment for brasses (copper-zinc base alloys). The variables (to the extent that these are known at present) that require
control are described together with possible means for controlling and standardizing these variables.
1.2 This practice is recommended only for brasses (copper-zinc base alloys). The use of this test environment is not
recommended for other copper alloys since the results may be erroneous, providing completely misleading rankings. This is
particularly true of alloys containing aluminum or nickel as deliberate alloying additions.
1.3 This practice is intended primarily where the test objective is to determine the relative stress-corrosion cracking
susceptibility of different brasses under the same or different stress conditions or to determine the absolute degree of stress
corrosion cracking susceptibility, if any, of a particular brass or brass component under one or more specific stress conditions.
Other legitimate test objectives for which this test solution may be used do, of course, exist. The tensile stresses present may be
known or unknown, applied or residual. The practice may be applied to wrought brass products or components, brass castings,
brass weldments, and so forth, and to all brasses. Strict environmental test conditions are stipulated for maximum assurance that
apparent variations in stress-corrosion susceptibility are attributable to real variations in the material being tested or in the tensile
stress level and not to environmental variations.
1.4 This practice relates solely to the preparation and control of the test environment. No attempt is made to recommend surface
preparation or finish, or both, as this may vary with the test objectives. Similarly, no attempt is made to recommend particular
stress-corrosion test specimen configurations or methods of applying the stress. Test specimen configurations that may be used are
referenced in Practice G30 and STP 425.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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 more specific safety hazard statements see Section 8.)
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
G30 Practice for Making and Using U-Bend Stress-Corrosion Test Specimens
3. Summary of Practice
3.1 The practice consists of completely and continuously immersing a stressed test specimen in an aqueous solution containing
++ + +
0.05 g-atom/L of Cu and 1 g-mol/L of NH and of pH 7.2. The copper is added as CuSO ·5H O and the NH as a mixture
4 4 2 4
of NH OH and (NH ) SO . The ratio of these latter two compounds is adjusted to give the desired pH. Exposure time, criterion
4 4 2 4
of failure, and so forth, are variable and not specifically recommended.
This practice 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 Feb. 1, 2011May 1, 2016. Published March 2011May 2016. Originally approved in 1973. Last previous edition approved in 20042011 as
G37–98(2004).G37 – 98 (2011). DOI: 10.1520/G0037-98R11.10.1520/G0037-98R16.
STP425, Stress Corrosion Testing, ASTM International.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G37 − 98 (2016)
4. Significance and Use
4.1 This test environment is believed to give an accelerated ranking of the relative or absolute degree of stress-corrosion
cracking susceptibility for different brasses. It has been found to correlate well with the corresponding service ranking in
environments that cause stress-corrosion cracking which is thought to be due to the combined presence of traces of moisture and
ammonia vapor. The extent to which the accelerated ranking correlates with the ranking obtained after long-term exposure to
environments containing corrodents other than ammonia is not at present known. Examples of such environments may be severe
−
marine atmospheres (Cl ), severe industrial atmospheres (predominantly SO ), and super-heated ammonia-free steam.
4.2 It is not possible at present to specify any particular time to failure (defined on the basis of any particular failure criteria)
in pH 7.2 Mattsson’s solution that corresponds to a distinction between acceptable and unacceptable stress-corrosion behavior in
brass alloys. Such particular correlations must be determined individually.
4.3 Mattsson’s solution of pH 7.2 may also cause stress independent general and intergranular corrosion of brasses to some
extent. 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 with small cross section specimens, high applied stress levels, long exposure
periods and stress-corrosion resistant alloys. Careful metallographic examination is recommended for correct diagnosis of the
cause of failure. Alternatively, unstressed control specimens may be exposed to evaluate the extent to which stress independent
corrosion degrades mechanical properties.
5. Apparatus
5.1 Any suitable inert container may be used to hold the test solution and test specimens during exposure. Glass or plastic is
highly recommended. The container should be fitted with a removable top to reduce evaporation during test, thus preventing dust
and other particulate matter from entering the environment, and facilitating periodic inspection of the specimens. The top should
not, however, be airtight, but instead should permit reasonably free access of laboratory air to the surface of the environment. The
container and top should not be transparent and should be fully opaque to light.
5.2 Specimen Holders, should be designed to insulate electrically the test specimens from each other and from any other bare
metal. They should also be completely inert to the test environment so that leaching of soluble components or direct reaction with
the test environment will not interfere with the test. The shape and form of the specimen holders and supports should be such that
they do not interfere with free access to the test environment to the test specimen and its stressed surfaces.
6. Reagents and Materials
6.1 Reagent grade copper sulfate crystals (CuSO ·5H O), ammonium sulfate crystals ((NH ) SO ), and concentrated
4 2 4 2 4
ammonium hydroxide solution (NH OH) (28 to 30 % NH assayed and 0.90 sp gr) conforming to the specifications of the
4 3
Committee on Analytical Reagents of the American Chemical Society shall be used.
6.2 Purity of Water—Reagent water Type IV (Specification D1193) shall be used to prepare the test solution.
7. Test Solution
++ +
7.1 The concentration of the test solution shall be 0.05 g-atom/L with respect to Cu and 1.0 g-mol/L with respect to NH .
The pH of the test solution shall be 7.2 + 0.3, −0.1 pH.
7.2 The test solution shall be prepared by completely dissolving 590.0 6 1.0 g
...