ASTM G1-03(2017)e1
(Practice)Standard Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens
Standard Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens
SIGNIFICANCE AND USE
4.1 The procedures given are designed to remove corrosion products without significant removal of base metal. This allows an accurate determination of the mass loss of the metal or alloy that occurred during exposure to the corrosive environment.
4.2 These procedures, in some cases, may apply to metal coatings. However, possible effects from the substrate must be considered.
SCOPE
1.1 This practice covers suggested procedures for preparing bare, solid metal specimens for tests, for removing corrosion products after the test has been completed, and for evaluating the corrosion damage that has occurred. Emphasis is placed on procedures related to the evaluation of corrosion by mass loss and pitting measurements. (Warning—In many cases the corrosion product on the reactive metals titanium and zirconium is a hard and tightly bonded oxide that defies removal by chemical or ordinary mechanical means. In many such cases, corrosion rates are established by mass gain rather than mass loss.)
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific warning statements, see 1.1 and 7.2.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: G1 − 03 (Reapproved 2017)
Standard Practice for
Preparing, Cleaning, and Evaluating Corrosion Test
Specimens
ThisstandardisissuedunderthefixeddesignationG1;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorially updated references in Section 2 in December 2017.
1. Scope A262Practices for Detecting Susceptibility to Intergranular
Attack in Austenitic Stainless Steels
1.1 This practice covers suggested procedures for preparing
D1193Specification for Reagent Water
bare, solid metal specimens for tests, for removing corrosion
D1384Test Method for Corrosion Test for Engine Coolants
products after the test has been completed, and for evaluating
in Glassware
thecorrosiondamagethathasoccurred.Emphasisisplacedon
D2776Methods of Test for Corrosivity of Water in the
procedures related to the evaluation of corrosion by mass loss
Absence of Heat Transfer (Electrical Methods) (With-
and pitting measurements. (Warning—In many cases the
drawn 1991)
corrosion product on the reactive metals titanium and zirco-
G16Guide for Applying Statistics to Analysis of Corrosion
nium is a hard and tightly bonded oxide that defies removal by
Data
chemical or ordinary mechanical means. In many such cases,
G31Guide for Laboratory Immersion Corrosion Testing of
corrosion rates are established by mass gain rather than mass
Metals
loss.)
G33Practice for Recording Data from Atmospheric Corro-
1.2 The values stated in SI units are to be regarded as
sion Tests of Metallic-Coated Steel Specimens
standard. No other units of measurement are included in this
G46Guide for Examination and Evaluation of Pitting Cor-
standard.
rosion
1.3 This standard does not purport to address all of the
G50Practice for Conducting Atmospheric Corrosion Tests
safety concerns, if any, associated with its use. It is the on Metals
responsibility of the user of this standard to establish appro-
G78Guide for Crevice Corrosion Testing of Iron-Base and
priate safety, health, and environmental practices and deter-
Nickel-Base Stainless Alloys in Seawater and Other
mine the applicability of regulatory limitations prior to use. Chloride-Containing Aqueous Environments
For specific warning statements, see 1.1 and 7.2.
G193Terminology and Acronyms Relating to Corrosion
1.4 This international standard was developed in accor-
3. Terminology
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the 3.1 See Terminology G193 for terms used in this practice.
Development of International Standards, Guides and Recom-
4. Significance and Use
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 4.1 The procedures given are designed to remove corrosion
productswithoutsignificantremovalofbasemetal.Thisallows
2. Referenced Documents
anaccuratedeterminationofthemasslossofthemetaloralloy
that occurred during exposure to the corrosive environment.
2.1 ASTM Standards:
4.2 These procedures, in some cases, may apply to metal
coatings. However, possible effects from the substrate must be
This practice is under the jurisdiction ofASTM Committee G01 on Corrosion
considered.
of Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory
Corrosion Tests.
5. Reagents and Materials
Current edition approved Nov. 1, 2017. Published December 2017. Originally
approved in 1967. Last previous edition approved in 2011 as G1–03 (2011). DOI: 5.1 Purity of Reagents—Reagent grade chemicals shall be
10.1520/G0001-03R17E01.
used in all tests. Unless otherwise indicated, it is intended that
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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G1 − 03 (2017)
all reagents conform to the specifications of the Committee on 6.3 For more searching tests of either the metal or the
Analytical Reagents of theAmerican Chemical Society where environment, standard surface finishes may be preferred. A
such specifications are available. Other grades may be used, suitable procedure might be:
provided it is first ascertained that the reagent is of sufficiently 6.3.1 Degreaseinanorganicsolventorhotalkalinecleaner.
high purity to permit its use without lessening the accuracy of
(See also Practice G31.)
the determination.
NOTE1—Hotalkaliesandchlorinatedsolventsmayattacksomemetals.
5.2 Purity of Water—Unless otherwise indicated, references NOTE 2—Ultrasonic cleaning may be beneficial in both pre-test and
post-test cleaning procedures.
to water shall be understood to mean reagent water as defined
by Type IV of Specification D1193.
6.3.2 Pickle in an appropriate solution if oxides or tarnish
are present. In some cases the chemical cleaners described in
6. Methods for Preparing Specimens for Test
Section 6 will suffice.
6.1 For laboratory corrosion tests that simulate exposure to
NOTE 3—Pickling may cause localized corrosion on some materials.
service environments, a commercial surface, closely resem-
6.3.3 Abradewithaslurryofanappropriateabrasiveorwith
blingtheonethatwouldbeusedinservice,willyieldthemost
an abrasive paper (see Practices A262 and Test Method
meaningful results.
D1384).Theedgesaswellasthefacesofthespecimensshould
6.2 It is desirable to mark specimens used in corrosion tests
be abraded to remove burrs.
with a unique designation during preparation. Several tech-
6.3.4 Rinse thoroughly, hot air dry, and store in desiccator.
niques may be used depending on the type of specimen and
6.4 When specimen preparation changes the metallurgical
test.
6.2.1 Stencil or Stamp—Most metallic specimens may be condition of the metal, other methods should be chosen or the
metallurgical condition must be corrected by subsequent treat-
marked by stenciling, that is, imprinting the designation code
into the metal surface using hardened steel stencil stamps hit ment.Forexample,shearingaspecimentosizewillcoldwork
and may possibly fracture the edges. Edges should be ma-
withahammer.Theresultingimprintwillbevisibleevenafter
substantial corrosion has occurred. However, this procedure chined.
introduces localized strained regions and the possibility of
6.5 The clean, dry specimens should be measured and
superficial iron contamination in the marked area.
weighed. Dimensions determined to the third significant figure
6.2.2 Electric engraving by means of a vibratory marking
and mass determined to the fifth significant figure are sug-
tool may be used when the extent of corrosion damage is
gested. When more significant figures are available on the
knowntobesmall.However,thisapproachtomarkingismuch
measuring instruments, they should be recorded.
more susceptible to having the marks lost as a result of
corrosion damage during testing.
7. Methods for Cleaning After Testing
6.2.3 Edgenotchingisespeciallyapplicablewhenextensive
7.1 Corrosion product removal procedures can be divided
corrosion and accumulation of corrosion products is antici-
into three general categories: mechanical, chemical, and elec-
pated. Long term atmospheric tests and sea water immersion
trolytic.
tests on steel alloys are examples where this approach is
7.1.1 An ideal procedure should remove only corrosion
applicable.Itisnecessarytodevelopacodesystemwhenusing
products and not result in removal of any base metal. To
edge notches.
determine the mass loss of the base metal when removing
6.2.4 Drilled holes may also be used to identify specimens
corrosion products, replicate uncorroded control specimens
whenextensivemetalloss,accumulationofcorrosionproducts,
shouldbecleanedbythesameprocedurebeingusedonthetest
or heavy scaling is anticipated. Drilled holes may be simpler
specimen. By weighing the control specimen before and after
and less costly than edge notching. A code system must be
cleaning, the extent of metal loss resulting from cleaning can
developed when using drilled holes. Punched holes should not
be utilized to correct the corrosion mass loss.
be used as they introduce residual strain.
6.2.5 When it is undesirable to deform the surface of
NOTE 4—It is desirable to scrape samples of corrosion products before
specimens after preparation procedures, for example, when
using any chemical techniques to remove them. These scrapings can then
be subjected to various forms of analyses, including perhaps X-ray
testing coated surfaces, tags may be used for specimen identi-
diffractiontodeterminecrystalformsaswellaschemicalanalysestolook
fication.Ametalorplasticwirecanbeusedtoattachthetagto
for specific corrodants, such as chlorides. All of the chemical techniques
the specimen and the specimen identification can be stamped
that are discussed in Section 7 tend to destroy the corrosion products and
on the tag. It is important to ensure that neither the tag nor the
thereby lose the information contained in these corrosion products. Care
wire will corrode or degrade in the test environment. It is also may be required so that uncorroded metal is not removed with the
corrosion products.
important to be sure that there are no galvanic interactions
between the tag, wire, and specimen.
7.1.2 Theproceduregivenin7.1.1maynotbereliablewhen
heavily corroded specimens are to be cleaned. The application
of replicate cleaning procedures to specimens with corroded
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
surfaces will often, even in the absence of corrosion products,
listed by the American Chemical Society, see Annual Standards for Laboratory
result in continuing mass losses. This is because a corroded
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
surface, particularly of a multiphase alloy, is often more
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. susceptible than a freshly machined or polished surface to
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G1 − 03 (2017)
corrosion by the cleaning procedure. In such cases, the 7.2.2 Intermittent removal of specimens from the cleaning
following method of determining the mass loss due to the solution for light brushing or ultrasonic cleaning can often
cleaning procedure is preferred. facilitate the removal of tightly adherent corrosion products.
7.1.2.1 Thecleaningprocedureshouldberepeatedonspeci- 7.2.3 Chemical cleaning is often followed by light brushing
mens several times. The mass loss should be determined after or ultrasonic cleaning in reagent water to remove loose
each cleaning by weighing the specimen. products.
7.1.2.2 Themasslossshouldbegraphedasafunctionofthe
7.3 Electrolytic cleaning can also be utilized for removal of
number of equal cleaning cycles as shown in Fig. 1.Two lines
corrosion products. Several useful methods for corrosion test
will be obtained: AB and BC. The latter will correspond to
specimens of iron, cast iron, or steel are given in Table A2.1.
corrosionofthemetalafterremovalofcorrosionproducts.The
7.3.1 Electrolytic cleaning should be preceded by brushing
mass loss due to corrosion will correspond approximately to
or ultrasonic cleaning of the test specimen to remove loose,
point B.
bulky corrosion products. Brushing or ultrasonic cleaning
7.1.2.3 To minimize uncertainty associated with corrosion
should also follow the electrolytic cleaning to remove any
of the metal by the cleaning method, a method should be
loose slime or deposits. This will help to minimize any
chosen to provide the lowest slope (near to horizontal) of line
redeposition of metal from reducible corrosion products that
BC.
would reduce the apparent mass loss.
7.1.3 Repeated treatment may be required for complete
7.4 Mechanicalprocedurescanincludescraping,scrubbing,
removal of corrosion products. Removal can often be con-
brushing, ultrasonic cleaning, mechanical shocking, and im-
firmed by examination with a low power microscope (for
pactblasting(forexample,gritblasting,water-jetblasting,and
example, 7× to 30×). This is particularly useful with pitted
so forth). These methods are often utilized to remove heavily
surfaceswhencorrosionproductsmayaccumulateinpits.This
encrusted corrosion products. Scrubbing with a nonmetallic
repeated treatment may also be necessary because of the
bristlebrushandamildabrasive-distilledwaterslurrycanalso
requirements of 7.1.2.1. Following the final treatment, the
be used to remove corrosion products.
specimensshouldbethoroughlyrinsedandimmediatelydried.
7.4.1 Vigorous mechanical cleaning may result in the re-
7.1.4 All cleaning solutions shall be prepared with water
movalofsomebasemetal;therefore,careshouldbeexercised.
and reagent grade chemicals.
These should be used only when other methods fail to provide
7.2 Chemical procedures involve immersion of the corro-
adequate removal of corrosion products. As with other
sion test specimen in a specific solution that is designed to
methods, correction for metal loss due to the cleaning method
removethecorrosionproductswithminimaldissolutionofany
is recommended. The mechanical forces used in cleaning
base metal. Several procedures are listed in Table A1.1. The
should be held as nearly constant as possible.
choice of chemical procedure to be used is partly a matter of
8. Assessment of Corrosion Damage
trial and error to establish the most effective method for a
specific metal and type of corrosion product scale.
8.1 The initial total surface area of the specimen (making
(Warning—These methods may be hazardous to personnel).
corrections for the areas associated with mounting holes) and
7.2.1 Chemical cleaning is often preceded by light brushing
the mass lost during the test are determined. The average
(non metallic bristle) or ultrasonic cleaning of the test speci-
corrosion rate may then be obtained as follows:
men to remove loose, bulky corrosion products.
CorrosionRate 5 K 3 W / A 3 T 3 D (1)
~ ! ~ !
where:
K = a constant (see 8.1.2),
T = time of exposure in hours,
A = area in cm ,
W = mass loss in grams, and
D = density in g/cm (see Appendix X1).
8.1.1 Corrosion rates are not necessarily constant
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