ASTM G48-11(2020)e1
(Test Method)Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use of Ferric Chloride Solution
Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use of Ferric Chloride Solution
SIGNIFICANCE AND USE
4.1 These test methods describe laboratory tests for comparing the resistance of stainless steels and related alloys to the initiation of pitting and crevice corrosion. The results may be used for ranking alloys in order of increasing resistance to pitting and crevice corrosion initiation under the specific conditions of these methods. Methods A and B are designed to cause the breakdown of Type 304 at room temperature.
4.2 The use of ferric chloride solutions is justified because it is related to, but not the same as, that within a pit or crevice site on a ferrous alloy in chloride bearing environments (1, 2).3 The presence of an inert crevice former of consistent dimension on a surface is regarded as sufficient specification of crevice geometry to assess relative crevice corrosion susceptibility.
4.3 The relative performance of alloys in ferric chloride solution tests has been correlated to performance in certain real environments, such as natural seawater at ambient temperature (3) and strongly oxidizing, low pH, chloride containing environments (4), but several exceptions have been reported (4-7).
4.4 Methods A, B, C, D, E, and F can be used to rank the relative resistance of stainless steels and nickel base alloys to pitting and crevice corrosion in chloride-containing environments. No statement can be made about resistance of alloys in environments that do not contain chlorides.
4.4.1 Methods A, B, C, D, E, and F were designed to accelerate the time to initiate localized corrosion relative to most natural environments. Consequently, the degree of corrosion damage that occurs during testing will generally be greater than that in natural environments in any similar time period.
4.4.2 No statement regarding localized corrosion propagation can be made based on the results of Methods A, B, C, D, E, or F.
4.4.3 Surface preparation can significantly influence results. Therefore, grinding and pickling of the specimen will mean that the results may not...
SCOPE
1.1 These test methods cover procedures for the determination of the resistance of stainless steels and related alloys to pitting and crevice corrosion (see Terminology G193) when exposed to oxidizing chloride environments. Six procedures are described and identified as Methods A, B, C, D, E, and F.
1.1.1 Method A—Ferric chloride pitting test.
1.1.2 Method B—Ferric chloride crevice test.
1.1.3 Method C—Critical pitting temperature test for nickel-base and chromium-bearing alloys.
1.1.4 Method D—Critical crevice temperature test for nickel-base and chromium-bearing alloys.
1.1.5 Method E—Critical pitting temperature test for stainless steels.
1.1.6 Method F—Critical crevice temperature test for stainless steels.
1.2 Method A is designed to determine the relative pitting resistance of stainless steels and nickel-base, chromium-bearing alloys, whereas Method B can be used for determining both the pitting and crevice corrosion resistance of these alloys. Methods C, D, E, and F allow for a ranking of alloys by minimum (critical) temperature to cause initiation of pitting corrosion and crevice corrosion, respectively, of stainless steels, nickel-base and chromium-bearing alloys in a standard ferric chloride solution.
1.3 These tests may be used to determine the effects of alloying additives, heat treatment, and surface finishes on pitting and crevice corrosion resistance.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.
1.5 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.
1.6 This international standard was developed in a...
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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: G48 − 11 (Reapproved 2020)
Standard Test Methods for
Pitting and Crevice Corrosion Resistance of Stainless
Steels and Related Alloys by Use of Ferric Chloride
Solution
ThisstandardisissuedunderthefixeddesignationG48;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Replaced Terminology G15 with Terminology G193, and other editorial changes made throughout in Dec. 2020.
1. Scope 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 These test methods cover procedures for the determina-
responsibility of the user of this standard to establish appro-
tion of the resistance of stainless steels and related alloys to
priate safety, health, and environmental practices and deter-
pitting and crevice corrosion (see Terminology G193) when
mine the applicability of regulatory limitations prior to use.
exposed to oxidizing chloride environments. Six procedures
1.6 This international standard was developed in accor-
are described and identified as Methods A, B, C, D, E, and F.
dance with internationally recognized principles on standard-
1.1.1 Method A—Ferric chloride pitting test.
ization established in the Decision on Principles for the
1.1.2 Method B—Ferric chloride crevice test.
Development of International Standards, Guides and Recom-
1.1.3 Method C—Criticalpittingtemperaturetestfornickel-
mendations issued by the World Trade Organization Technical
base and chromium-bearing alloys.
Barriers to Trade (TBT) Committee.
1.1.4 Method D—Critical crevice temperature test for
nickel-base and chromium-bearing alloys.
2. Referenced Documents
1.1.5 Method E—Critical pitting temperature test for stain-
2.1 ASTM Standards:
less steels.
A262Practices for Detecting Susceptibility to Intergranular
1.1.6 Method F—Critical crevice temperature test for stain-
Attack in Austenitic Stainless Steels
less steels.
D1193Specification for Reagent Water
1.2 Method A is designed to determine the relative pitting
E691Practice for Conducting an Interlaboratory Study to
resistance of stainless steels and nickel-base, chromium-
Determine the Precision of a Test Method
bearing alloys, whereas Method B can be used for determining
E1338Guide for Identification of Metals and Alloys in
boththepittingandcrevicecorrosionresistanceofthesealloys.
Computerized Material Property Databases
Methods C, D, E, and F allow for a ranking of alloys by
G1Practice for Preparing, Cleaning, and Evaluating Corro-
minimum (critical) temperature to cause initiation of pitting
sion Test Specimens
corrosion and crevice corrosion, respectively, of stainless
G46Guide for Examination and Evaluation of Pitting Cor-
steels, nickel-base and chromium-bearing alloys in a standard
rosion
ferric chloride solution.
G107Guide for Formats for Collection and Compilation of
1.3 These tests may be used to determine the effects of
Corrosion Data for Metals for Computerized Database
alloying additives, heat treatment, and surface finishes on
Input
pitting and crevice corrosion resistance.
G193Terminology and Acronyms Relating to Corrosion
1.4 The values stated in SI units are to be regarded as
3. Terminology
standard. The values given in parentheses after SI units are
providedforinformationonlyandarenotconsideredstandard. 3.1 Definitions of Terms Specific to This Standard:
3.1.1 critical crevice temperature, n—the minimum tem-
perature (°C) to produce crevice attack at least 0.025mm
These test methods are under the jurisdiction of ASTM Committee G01 on
Corrosion of Metals and are the direct responsibility of Subcommittee G01.05 on
Laboratory Corrosion Tests. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2020. Published December 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1976. Last previous edition approved in 2015 as G48–11 (2015). DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/G0048-11R20E01. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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G48 − 11 (2020)
NOTE 2—When testing as-welded, cylindrical, or other non-flat
(0.001in.) deep on the bold surface of the specimen beneath
samples, the standard crevice formers will not provide uniform contact.
the crevice washer, edge attack ignored.
The use of contoured crevice formers may be considered in such
3.1.2 critical pitting temperature, n—the minimum tem-
situations, but the use of a pitting test (Practices A, C, or E) should be
considered.
perature (°C) to produce pitting attack at least 0.025mm
(0.001in.) deep on the bold surface of the specimen, edge
5. Apparatus
attack ignored.
5.1 Glassware—Methods A, B, C, D, E, and F provide an
3.2 The terminology used herein, if not specifically defined
option to use either wide mouth flasks or suitable sized test
otherwise, shall be in accordance with Terminology G193.
tubes.Condensersarerequiredforelevatedtemperaturetesting
Definitions provided herein and not given in Terminology
when solution evaporation may occur. Glass cradles or hooks
G193 are limited only to this standard.
also may be required.
5.1.1 Flask Requirements, 1000mL wide mouth. Tall form
4. Significance and Use
or Erlenmeyer flasks can be used. The mouth of the flask shall
4.1 These test methods describe laboratory tests for com-
have a diameter of about 40 mm (1.6 in.) to allow passage of
paringtheresistanceofstainlesssteelsandrelatedalloystothe
the test specimen and the support.
initiation of pitting and crevice corrosion. The results may be
5.1.2 Test Tube Requirements, the diameter of the test tube
used for ranking alloys in order of increasing resistance to
shall also be about 40 mm (1.6 in.) in diameter. If testing
pitting and crevice corrosion initiation under the specific
requires use of a condenser (described below), the test tube
conditions of these methods. MethodsAand B are designed to
length shall be about 300 mm (about 12 in.); otherwise, the
cause the breakdown of Type 304 at room temperature.
length can be about 150mm to 200 mm (about 6 in. to 8 in.).
4.2 Theuseofferricchloridesolutionsisjustifiedbecauseit
5.1.3 Condensers, Vents and Covers:
isrelatedto,butnotthesameas,thatwithinapitorcrevicesite
5.1.3.1 Avariety of condensers may be used in conjunction
onaferrousalloyinchloridebearingenvironments (1, 2). The
with the flasks described in 5.1.1. These include the cold
presence of an inert crevice former of consistent dimension on
finger-type (see, for example, Practices A262, Practice C) or
a surface is regarded as sufficient specification of crevice
Allihn type condensers having straight tube ends or tapered
geometry to assess relative crevice corrosion susceptibility.
ground joints. Straight end condensers can be inserted through
a bored rubber stopper. Likewise, a simple U tube condenser
4.3 The relative performance of alloys in ferric chloride
can be fashioned.
solutiontestshasbeencorrelatedtoperformanceincertainreal
environments, such as natural seawater at ambient temperature
NOTE3—Theuseofgroundjointcondensersrequiresthatthemouthof
(3) and strongly oxidizing, low pH, chloride containing envi-
the flask have a corresponding joint.
ronments (4), but several exceptions have been reported (4-7).
5.1.3.2 U Tube Condensers, fitted through holes in an
4.4 Methods A, B, C, D, E, and F can be used to rank the appropriatesizerubberstoppercanbeusedinconjunctionwith
relative resistance of stainless steels and nickel base alloys to the 300mm test tube described in 5.1.2.
pitting and crevice corrosion in chloride-containing environ- 5.1.3.3 When evaporation is not a significant problem,
ments. No statement can be made about resistance of alloys in flasks can be covered with a watch glass. Also, flasks as well
environments that do not contain chlorides. as test tubes can be covered with loosely fitted stoppers or
4.4.1 Methods A, B, C, D, E, and F were designed to plastic or paraffin type wraps.
accelerate the time to initiate localized corrosion relative to
NOTE 4—Venting must always be considered due to the possible build
most natural environments. Consequently, the degree of corro-
up of gas pressure that may result from the corrosion process.
siondamagethatoccursduringtestingwillgenerallybegreater
5.1.4 Specimen Supports:
than that in natural environments in any similar time period.
5.1.4.1 One advantage of using test tubes is that specimen
4.4.2 No statement regarding localized corrosion propaga-
supportsarenotrequired.However,placementofthespecimen
tion can be made based on the results of MethodsA, B, C, D,
does create the possible opportunity for crevice corrosion to
E, or F.
occur along the edge.
4.4.3 Surfacepreparationcansignificantlyinfluenceresults.
Therefore, grinding and pickling of the specimen will mean NOTE 5—See 14.2 concerning edge attack.
that the results may not be representative of the conditions of
5.1.4.2 When using flasks, specimens can be supported on
the actual piece from which the sample was taken.
cradles or hooks. Cradles, such as those shown in Fig. 1,
eliminate the necessity for drilling a support hole in the test
NOTE 1—Grinding or pickling on stainless steel surfaces may destroy
the passive layer. A 24h air passivation after grinding or pickling is specimen. While the use of hooks requires that a specimen
sufficient to minimize these differences (8).
supportholebeprovided,thehooks,ascontrastedtothecradle,
are easier to fashion. Moreover, they create only one potential
4.4.4 The procedures in Methods C, D, E, and F for
crevice site whereas multiple sites are possible with the cradle.
measuring critical pitting corrosion temperature and critical
crevice corrosion temperature have no bias because the values
NOTE 6—A TFE-fluorocarbon cradle may be substituted for glass.
are defined only in terms of these test methods.
5.1.4.3 TheuseofsupportsforMethodsB,D,andFcrevice
corrosion specimens is optional.
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard. 5.2 Water or Oil Bath, constant temperature.
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G48 − 11 (2020)
FIG. 1 Examples of Glass Cradles that Can Be Used to Support the Specimen
5.2.1 ForMethodsAandB,therecommendedtesttempera- design shown in Fig. 2 is one of a number of variations of the
tures are 22°C 62°Cor50°C 6 2°C, or both. multiple crevice assembly that is in use and commercially
5.2.2 For Methods C, D, E, and F, the bath shall have the available.
capability of providing constant temperature between 0°C and
NOTE 10—When testing as-welded, cylindrical, or other non-flat
85°C 6 1°C.
samples, the standard crevice formers will not provide uniform contact.
The use of contoured crevice formers may be considered in such
5.3 Crevice Formers—Method B:
situations, but the use of pitting tests (Practices C or E) should be
5.3.1 Cylindrical TFE-fluorocarbon Blocks, two for each
considered. The problem of matching the crevice former to the sample
test specimen. Each block shall be 12.7mm (0.5 in.) in
surface becomes more difficult as the radius of the surface becomes
diameter and 12.7mm high, with perpendicular grooves smaller.
1.6mm(0.063in.)wideand1.6mmdeepcutinthetopofeach
5.4.2 Reuse of Multiple Crevice Assemblies, when as-
cylinderforretentionoftheO-ringorrubberbands.Blockscan
sembled to the specified torque, the TFE-fluorocarbon seg-
be machined from bar or rod stock.
mented washers should not deform during testing. Before
reuse, each washer should be inspected for evidence of
NOTE 7—When testing as-welded, cylindrical, or other non-flat
samples, the standard crevice formers will not provide uniform contact. distortion and other damage. If so affected, they should be
The use of contoured crevice formers may be considered in such
discarded. In some cases, the crevice formers may become
situations,buttheuseofthepittingtest(PracticeA)shouldbeconsidered.
stained with corrosion products from the tested alloy.
The problem of matching the crevice former to the sample surface
Generally,thisstainingcanberemovedbyimmersionindilute
becomes more difficult as the radius of the surface becomes smaller.
HCl (for example, 5 % to 10 % by volume) at room
5.3.2 Fluorinated Elastomers O-rings, or Rubber Bands,
temperature, followed by brushing with mild detergent and
(low sulfur (0.02% max)), two for each test specimen.
through rinsing with water.
NOTE 8—It is good practice to use all O-rings or all rubber bands in a 5.4.3 Fasteners, one alloy UNS N10276 (or similarly resis-
given test program.
tant alloy) fastener is required for each assembly. Each
assembly comprises a threaded bolt and nut plus two washers.
5.3.2.1 O-rings shall be 1.75 mm (0.070 in.) in cross
The bolt length shall be sized to allow passage through the
section; one ring with an inside diameter of about 20 mm
mouth of the glassware described in 5.1.
(0.8in.) and one with an inside diameter of about 30 mm (1.1
in.). Rubber bands shall be one No. 12 (38mm (1.5in.) long)
5.5 Tools and Instruments:
and one No. 14 (51mm (2in.) long). 1
5.5.1 A 6.35mm ( ⁄4in.) torque limiting nut driver is re-
quired for assembly of the Methods D and F crevice test
NOTE 9—Rubber bands or O-rings can be boiled in water prior to use
specimen.
to ensure the removal of water-soluble ingredients that might affect
corrosion.
The sole source of supply of the apparatus known to the committee at this time
5.4 Crevice Formers—Methods D and F:
is Metal Samples Co., Inc., P.O. Box 8, Route 1 Box 152, Munford, AL 36268. If
5.4.1 A Multiple Crevice Assembly (MCA), consisting of
you are aware of alternative suppliers, please provide this information to ASTM
two TFE-fluorocarbon segmented washers, each having a
Headquarters.Your comments will receive careful consideration at a meeting of the
number of grooves and plateaus, shall be used. The crevice responsible technical committee, which you may attend.
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G48 − 11 (2020)
7.2 When specimens are cut by shearing, the deformed
material should be removed by machining or grinding prior to
testing unless the corrosion resistance of the sheared edges is
being evaluated. It is good practice to remove deformed edges
to the thickness of the material.
7.3 For Methods D and F, a sufficient
...
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