ASTM G48-03(2009)
(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
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.
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). 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.
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).
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.
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.
No statement regarding localized corrosion propagation can be made based on the results of Methods A, B, C, D, E or F.
Surface preparation can significantly influence results. Therefore, grinding and pickling of the specimen will mean that the results may not be representative of the conditions of t...
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 G 15) 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 the standard. Other units are given in parentheses for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: G48 – 03 (Reapproved 2009)
Standard Test Methods for
Pitting and Crevice Corrosion Resistance of Stainless
Steels and Related Alloys by Use of Ferric Chloride
Solution
ThisstandardisissuedunderthefixeddesignationG48;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.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.
1.1 These test methods cover procedures for the determina-
tion of the resistance of stainless steels and related alloys to
2. Referenced Documents
pitting and crevice corrosion (see Terminology G15) when
2.1 ASTM Standards:
exposed to oxidizing chloride environments. Six procedures
A262 Practices for Detecting Susceptibility to Intergranular
are described and identified as Methods A, B, C, D, E, and F.
Attack in Austenitic Stainless Steels
1.1.1 Method A—Ferric chloride pitting test.
D1193 Specification for Reagent Water
1.1.2 Method B—Ferric chloride crevice test.
E691 Practice for Conducting an Interlaboratory Study to
1.1.3 Method C—Critical pitting temperature test for
Determine the Precision of a Test Method
nickel-base and chromium-bearing alloys.
E1338 Guide for Identification of Metals and Alloys in
1.1.4 Method D—Critical crevice temperature test for
Computerized Material Property Databases
nickel-base and chromium-bearing alloys.
G1 Practice for Preparing, Cleaning, and Evaluating Corro-
1.1.5 Method E—Critical pitting temperature test for stain-
sion Test Specimens
less steels.
G15 Terminology Relating to Corrosion and Corrosion
1.1.6 Method F—Critical crevice temperature test for stain-
Testing
less steels.
G46 Guide for Examination and Evaluation of Pitting
1.2 Method A is designed to determine the relative pitting
Corrosion
resistance of stainless steels and nickel-base, chromium-
G107 Guide for Formats for Collection and Compilation of
bearing alloys, whereas Method B can be used for determining
Corrosion Data for Metals for Computerized Database
boththepittingandcrevicecorrosionresistanceofthesealloys.
Input
Methods C, D, E and F allow for a ranking of alloys by
minimum (critical) temperature to cause initiation of pitting
3. Terminology
corrosion and crevice corrosion, respectively, of stainless
3.1 Definitions of Terms Specific to This Standard:
steels, nickel-base and chromium-bearing alloys in a standard
3.1.1 critical crevice temperature, n—the minimum tem-
ferric chloride solution.
perature (°C) to produce crevice attack at least 0.025-mm
1.3 These tests may be used to determine the effects of
(0.001-in.) deep on the bold surface of the specimen beneath
alloying additives, heat treatment, and surface finishes on
the crevice washer, edge attack ignored.
pitting and crevice corrosion resistance.
3.1.2 critical pitting temperature, n— the minimum tem-
1.4 The values stated in SI units are to be regarded as the
perature (°C) to produce pitting attack at least 0.025-mm
standard. Other units are given in parentheses for information
(0.001-in.) deep on the bold surface of the specimen, edge
only.
attack ignored.
1.5 This standard does not purport to address all of the
3.2 The terminology used herein, if not specifically defined
safety concerns, if any, associated with its use. It is the
otherwise, shall be in accordance with Terminology G15.
responsibility of the user of this standard to establish appro-
Definitions provided herein and not given in Terminology G15
are limited only to this standard.
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 May 1, 2009. Published May 2009. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1976. Last previous edition approved in 2003 as G48–03. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/G0048-03R09. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G48 – 03 (2009)
4. Significance and Use 5.1.2 Test Tube Requirements, the diameter of the test tube
shall also be about 40 mm (1.6 in.) in diameter. If testing
4.1 These test methods describe laboratory tests for com-
requires use of a condenser (described below), the test tube
paring the resistance of stainless steels and related alloys to the
length shall be about 300 mm (about 12 in.); otherwise, the
initiation of pitting and crevice corrosion. The results may be
length can be about 150 to 200 mm (about 6 in. to 8 in.).
used for ranking alloys in order of increasing resistance to
5.1.3 Condensers, Vents and Covers:
pitting and crevice corrosion initiation under the specific
5.1.3.1 Avariety of condensers may be used in conjunction
conditions of these methods. MethodsAand B are designed to
with the flasks described in 5.1.1. These include the cold
cause the breakdown of Type 304 at room temperature.
finger-type (see, for example, Practices A262, Practice C) or
4.2 Theuseofferricchloridesolutionsisjustifiedbecauseit
Allihn type condensers having straight tube ends or tapered
isrelatedto,butnotthesameas,thatwithinapitorcrevicesite
ground joints. Straight end condensers can be inserted through
onaferrousalloyinchloridebearingenvironments(1,2). The
a bored rubber stopper. Likewise, a simple U tube condenser
presence of an inert crevice former of consistent dimension on
can be fashioned.
a surface is regarded as sufficient specification of crevice
geometry to assess relative crevice corrosion susceptibility.
NOTE 2—The use of ground joint condensers requires that the mouth of
4.3 The relative performance of alloys in ferric chloride
the flask have a corresponding joint.
solution tests has been correlated to performance in certain real
5.1.3.2 U Tube Condensers, fitted through holes in an
environments, such as natural seawater at ambient temperature
appropriatesizerubberstoppercanbeusedinconjunctionwith
(3) and strongly oxidizing, low pH, chloride containing envi-
the 300-mm test tube described in 5.1.2.
ronments (4), but several exceptions have been reported (4-7).
5.1.3.3 When evaporation is not a significant problem,
4.4 Methods A, B, C, D, E, and F can be used to rank the
flasks can be covered with a watch glass. Also, flasks as well
relative resistance of stainless steels and nickel base alloys to
as test tubes can be covered with loosely fitted stoppers or
pitting and crevice corrosion in chloride-containing environ-
plastic or paraffin type wraps.
ments. No statement can be made about resistance of alloys in
environments that do not contain chlorides.
NOTE 3—Venting must always be considered due to the possible build
up of gas pressure that may result from the corrosion process.
4.4.1 Methods A, B, C, D, E, and F were designed to
accelerate the time to initiate localized corrosion relative to
5.1.4 Specimen Supports:
most natural environments. Consequently, the degree of corro-
5.1.4.1 One advantage of using test tubes is that specimen
siondamagethatoccursduringtestingwillgenerallybegreater
supports are not required. However, placement of the specimen
than that in natural environments in any similar time period.
does create the possible opportunity for crevice corrosion to
4.4.2 No statement regarding localized corrosion propaga-
occur along the edge.
tion can be made based on the results of Methods A, B, C, D,
EorF. NOTE 4—See 14.2 concerning edge attack.
4.4.3 Surface preparation can significantly influence results.
5.1.4.2 When using flasks, specimens can be supported on
Therefore, grinding and pickling of the specimen will mean
cradles or hooks. Cradles, such as those shown in Fig. 1,
that the results may not be representative of the conditions of
eliminate the necessity for drilling a support hole in the test
the actual piece from which the sample was taken.
specimen. While the use of hooks requires that a specimen
NOTE 1—Grinding or pickling on stainless steel surfaces may destroy supportholebeprovided,thehooks,ascontrastedtothecradle,
the passive layer. A 24-h air passivation after grinding or pickling is
are easier to fashion. Moreover, they create only one potential
sufficient to minimize these differences (8).
crevice site whereas multiple sites are possible with the cradle.
4.4.4 The procedures in Methods C, D, E and F for
NOTE 5—A TFE-fluorocarbon cradle may be substituted for glass.
measuring critical pitting corrosion temperature and critical
5.1.4.3 The use of supports for Methods B, D, and F crevice
crevice corrosion temperature have no bias because the values
corrosion specimens is optional.
are defined only in terms of these test methods.
5.2 Water or Oil Bath, constant temperature.
5. Apparatus 5.2.1 For MethodsAand B, the recommended test tempera-
tures are 22 6 2°C or 50 6 2°C, or both.
5.1 Glassware—Methods A, B, C, D, E, and F provide an
5.2.2 For Methods C, D, E, and F, the bath shall have the
option to use either wide mouth flasks or suitable sized test
capability of providing constant temperature between 0°C and
tubes. Condensers are required for elevated temperature testing
85°C 6 1°C.
when solution evaporation may occur. Glass cradles or hooks
5.3 Crevice Formers—Method B:
also may be required.
5.3.1 Cylindrical TFE-fluorocarbon Blocks, two for each
5.1.1 Flask Requirements, 1000-mL wide mouth. Tall form
test specimen. Each block shall be 12.7-mm (0.5 in.) in
or Erlenmeyer flasks can be used. The mouth of the flask shall
diameter and 12.7-mm high, with perpendicular grooves
have a diameter of about 40 mm (1.6 in.) to allow passage of
1.6-mm (0.063 in.) wide and 1.6-mm deep cut in the top of
the test specimen and the support.
each cylinder for retention of the O-ring or rubber bands.
Blocks can be machined from bar or rod stock.
5.3.2 Fluorinated Elastomers O-rings, or Rubber Bands,
The boldface numbers in parentheses refer to the list of references at the end of
this standard. (low sulfur (0.02 % max)), two for each test specimen.
G48 – 03 (2009)
FIG. 1 Examples of Glass Cradles that Can Be Used to Support the Specimen
NOTE 6—It is good practice to use all O-rings or all rubber bands in a
multiple crevice assembly that is in use and commercially
given test program.
available.
5.4.2 Reuse of Multiple Crevice Assemblies, when as-
5.3.2.1 O-rings shall be 1.75 mm (0.070 in.) in cross
sembled to the specified torque, the TFE-fluorocarbon seg-
section; one ring with an inside diameter of about 20 mm (0.8
mented washers should not deform during testing. Before
in.) and one with an inside diameter of about 30 mm (1.1 in.).
reuse, each washer should be inspected for evidence of
Rubber bands shall be one No. 12 (38-mm (1.5-in.) long) and
distortion and other damage. If so affected, they should be
one No. 14 (51-mm (2-in.) long).
discarded. In some cases, the crevice formers may become
stained with corrosion products from the tested alloy. Gener-
NOTE 7—Rubber bands or O-rings can be boiled in water prior to use
to ensure the removal of water-soluble ingredients that might affect
ally, this staining can be removed by immersion in dilute HCl
corrosion.
(for example, 5-10% by volume) at room temperature, fol-
lowed by brushing with mild detergent and through rinsing
5.4 Crevice Formers—Methods D and F:
with water.
5.4.1 A Multiple Crevice Assembly (MCA), consisting of
5.4.3 Fasteners, one alloy UNS N10276 (or similarly resis-
two TFE-fluorocarbon segmented washers, each having a
tant alloy) fastener is required for each assembly. Each
number of grooves and plateaus, shall be used. The crevice
assembly comprises a threaded bolt and nut plus two washers.
design shown in Fig. 2 is one of a number of variations of the
The bolt length shall be sized to allow passage through the
mouth of the glassware described in 5.1.
5.5 Tools and Instruments:
5.5.1 A 6.35-mm ( ⁄4-in.) torque limiting nut driver is
required for assembly of the Methods D and F crevice test
specimen.
5.5.2 Low Power Microscope, (for example, 203 magnifi-
cation) for pit detection.
5.5.3 Needle Point Dial Depth Indicator or Focusing Mi-
croscope, to determine the depth of pitting or crevice corro-
sion, or both.
5.5.4 Electronic Balance (optional), to determine specimen
mass to the nearest 0.0001 g.
5.5.5 Camera (optional), to photographically record the
mode and extent of any localized corrosion.
The sole source of supply of the apparatus known to the committee at this time
is Metal Samples Co., Inc., P.O. Box 8, Route 1 Box 152, Munford, AL 36268. If
you are aware of alternative suppliers, please provide this information to ASTM
Headquarters.Your comments will receive careful consideration at a meeting of the
FIG. 2 TFE-fluorocarbon Crevice Washers responsible technical committee, which you may attend.
G48 – 03 (2009)
6. Ferric Chloride Test Solution a constant temperature bath and allow the test solution to come
to the equilibrium temperature of interest. Recommended
6.1 For Methods A and B, dissolve 100 g of reagent grade
temperatures for evaluation are 22 6 2°C and 50 6 2°C.
ferric chloride, FeCl ·6H O, in 900 mL of Type IV reagent
3 2
8.1.2 Place the specimen in a glass cradle and immerse in
water (Specification D1193) (about 6 % FeCl by mass). Filter
the test solution after it has reached the desired temperature.
through glass wool or filter paper to remove insoluble particles
Maintain test solution temperature throughout the test.
if present.
8.1.3 Cover the test vessel with a watch glass.Areasonable
6.2 For Methods C, D, E, and F, dissolve 68.72 g of reagent
test period is 72 h, although variations may be used at the
grade ferric chloride, FeCl ·6H O in 600 mL of reagent water
3 2
discretionoftheinvestigatoranddependonthematerialsbeing
and add 16 mL of reagent grade concentrated (36.5–38.0 %)
evaluated.
hydrochloric acid (HCl). This will produce a solution contain-
8.1.4 Remove the specimens, rinse with water and scrub
ing about 6 % FeCl by mass and 1 % HCl resulting in a pH
with a nylon bristle brush under running water to remove
controlled environment over the test temperatures (9).
corrosion products, dip in acetone or methanol, and air-dry.
7. Test Specimens
Ultrasonic cleaning may be used as a substitute method in
cases in which it is difficult to remove corrosion products fr
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:G48–00 Designation: G 48 – 03 (Reapproved 2009)
Standard Test Methods for
Pitting and Crevice Corrosion Resistance of Stainless
Steels and Related Alloys by Use of Ferric Chloride
Solution
ThisstandardisissuedunderthefixeddesignationG 48;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 These test methods cover procedures for the determination of the resistance of stainless steels and related alloys to pitting
andcrevicecorrosion(seeTerminologyG 15)whenexposedtooxidizingchlorideenvironments.FourSixproceduresaredescribed
and identified as Methods A, B, C, D, E, and D. 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. —Critical pitting temperature test for nickel-base and chromium-bearing
alloys.
1.1.4 Method D—Critical crevice temperature test.
1.2MethodAisdesignedtodeterminetherelativepittingresistanceofstainlesssteelsandnickel-base,chromium-bearingalloys,
whereas Method B can be used for determining both the pitting and crevice corrosion resistance of these alloys. Methods C and
D allow for a ranking of alloys by minimum (critical) temperature to cause initiation of pitting corrosion and crevice corrosion,
respectively, of stainless steels and nickel-base, chromium-bearing alloys in a standard ferric chloride solution. —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 the standard. Other units are given in parentheses for information only.
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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
A 262 Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels
D 1193 Specification for Reagent Water
E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E 1338 Guide for the Identification of Metals and Alloys in Computerized Material Property Databases
G1 Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens
G15 Terminology Relating to Corrosion and Corrosion Testing
G46 Guide for Examination and Evaluation of Pitting Corrosion
G 107 Guide for Formats for Collection and Compilation of Corrosion Data for Metals for Computerized Database Input
These test methods are under the jurisdiction of ASTM Committee G01 on Corrosion of Metals,Metals and are the direct responsibility of Subcommittee G01.05 on
Laboratory Corrosion Tests.
Current edition approved May 10, 2000. Published June 2000. Originally published as G48–76. Last previous edition G48–99a.
Current edition approved May 1, 2009. Published May 2009. Originally approved in 1976. Last previous edition approved in 2003 as G 48–03.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book ofASTM Standards
, Vol 01.03.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.
G 48 – 03 (2009)
3. Terminology
3.1 DefinitionDefinitions of Terms Specific to This Standard:
3.1.1 critical crevice temperature, n—the minimum temperature (°C) to produce crevice attack at least 0.025-mm (0.001-in.)
deep on the bold surface of the specimen beneath the crevice washer, edge attack ignored.
3.1.2 critical pitting temperature, n— the minimum temperature (°C) to produce pitting attack at least 0.025-mm (0.001-in.)
deep on the bold surface of the specimen, edge attack ignored.
3.2 The terminology used herein, if not specifically defined otherwise, shall be in accordance with Terminology G 15.
Definitions provided herein and not given in Terminology G 15 are limited only to this standard.
4. 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). 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 MethodsA, B, C, D, E, and DF 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 MethodsA, B, C, D, E, and DF were designed to accelerate the time to initiate localized corrosion relative to most natural
environments.Consequently,thedegreeofcorrosiondamagethatoccursduringtestingwillgenerallybegreaterthanthatinnatural
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
D. F.
4.4.3 Surface preparation can significantly influence results. Therefore, grinding and pickling of the specimen will mean that
the results may not be representative of the conditions of the actual piece from which the sample was taken.
NOTE 1—Grinding or pickling on stainless steel surfaces may destroy the passive layer. A 24-h air passivation after grinding or pickling is sufficient
to minimize these differences (8).
4.4.4 The procedures in Methods C, D, E and DF for measuring critical pitting corrosion temperature and critical crevice
corrosion temperature have no bias because the values are defined only in terms of these test methods.
5. Apparatus
5.1 Glassware—MethodsA, B, C, D, E, and DF provide an option to use either wide mouth flasks or suitable sized test tubes.
Condensers are required for elevated temperature testing when solution evaporation may occur. Glass cradles or hooks also may
be required.
5.1.1 Flask Requirements, 1000-mLwide mouth. Tall form or Erlenmeyer flasks can be used. The mouth of the flask shall have
a diameter of about 40 mm (1.6 in.) to allow passage of the test specimen and the support.
5.1.2 Test Tube Requirements, the diameter of the test tube shall also be about 40 mm (1.6 in.) in diameter. If testing requires
use of a condenser (described below), the test tube length shall be about 300 mm (about 12 in.); otherwise, the length can be about
150 to 200 mm (about 6 in. to 8 in.).
5.1.3 Condensers, Vents and Covers :
5.1.3.1 Avarietyofcondensersmaybeusedinconjunctionwiththeflasksdescribedin5.1.1.Theseincludethecoldfinger-type
(see, for example, Practices A 262, Practice C) or Allihn type condensers having straight tube ends or tapered ground joints.
Straight end condensers can be inserted through a bored rubber stopper. Likewise, a simple U tube condenser can be fashioned.
NOTE 2—The use of ground joint condensers requires that the mouth of the flask have a corresponding joint.
5.1.3.2 U Tube Condensers, fitted through holes in an appropriate size rubber stopper can be used in conjunction with the
300-mm test tube described in 5.1.2.
5.1.3.3 Whenevaporationisnotasignificantproblem,flaskscanbecoveredwithawatchglass.Also,flasksaswellastesttubes
can be covered with loosely fitted stoppers or plastic or paraffin type wraps.
Annual Book of ASTM Standards, Vol 11.01.
The boldface numbers in parentheses refer to the list of references at the end of this standard.
G 48 – 03 (2009)
NOTE 3—Venting must always be considered due to the possible build up of gas pressure that may result from the corrosion process.
5.1.4 Specimen Supports:
5.1.4.1 One advantage of using test tubes is that specimen supports are not required. However, placement of the specimen does
create the possible opportunity for crevice corrosion to occur along the edge.
NOTE 4—See 12.2 14.2 concerning edge attack.
5.1.4.2 When using flasks, specimens can be supported on cradles or hooks. Cradles, such as those shown in Fig. 1, eliminate
the necessity for drilling a support hole in the test specimen. While the use of hooks requires that a specimen support hole be
provided, the hooks, as contrasted to the cradle, are easier to fashion. Moreover, they create only one potential crevice site whereas
multiple sites are possible with the cradle.
NOTE 5—A TFE-fluorocarbon cradle may be substituted for glass.
5.1.4.3 The use of supports for Methods B, D, and DF crevice corrosion specimens is optional.
5.2 Water or Oil Bath, constant temperature.
5.2.1 For Methods A and B, the recommended test temperatures are 22 6 2°C or 50 6 2°C, or both.
5.2.2 For Methods C, D, E, and D,F, the bath shall have the capability of providing constant temperature between 0°C and 85°C
6 1°C.
5.3 Crevice Formers—Method B:
5.3.1 Cylindrical TFE-fluorocarbon Blocks, two for each test specimen. Each block shall be 12.7-mm (0.5 in.) in diameter and
12.7-mm high, with perpendicular grooves 1.6-mm (0.063 in.) wide and 1.6-mm deep cut in the top of each cylinder for retention
of the O-ring or rubber bands. Blocks can be machined from bar or rod stock.
5.3.2 Fluorinated Elastomers O-rings, or Rubber Bands, (low sulfur (0.02 % max)), two for each test specimen.
NOTE 6—It is good practice to use all O-rings or all rubber bands in a given test program.
5.3.2.1 O-rings shall be 1.75 mm (0.070 in.) in cross section; one ring with an inside diameter of about 20 mm (0.8 in.) and
one with an inside diameter of about 30 mm (1.1 in.). Rubber bands shall be one No. 12 (38-mm (1.5-in.) long) and one No. 14
(51-mm (2-in.) long).
NOTE 7—Rubber bands or O-rings can be boiled in water prior to use to ensure the removal of water-soluble ingredients that might affect corrosion.
5.4 Crevice Formers—Method DCrevice Formers—Methods D and F:
5.4.1 A Multiple Crevice Assembly (MCA), consisting of two TFE-fluorocarbon segmented washers, each having a number of
grooves and plateaus, shall be used. The crevice design shown in Fig. 2 is one of a number of variations of the multiple crevice
assembly that is in use and commercially available.
Annual Book of ASTM Standards, Vol 14.02.
The sole source of supply of the apparatus known to the committee at this time is Metal Samples Co., Inc., P.O. Box 8, Route 1 Box 152, Munford, AL 36268. If you
are aware of alternative suppliers, please provide this information toASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible
technical committee, which you may attend.
FIG. 1 Examples of Glass Cradles that Can Be Used to Support the Specimen
G 48 – 03 (2009)
FIG. 2 TFE-fluorocarbon Crevice Washers
5.4.2 Reuse of Multiple Crevice Assemblies, when assembled to the specified torque, the TFE-fluorocarbon segmented washers
should not deform during testing. Before reuse, each washer should be inspected for evidence of distortion and other damage. If
so affected, they should be discarded. In some cases, the crevice formers may become stained with corrosion products from the
tested alloy. Generally, this staining can be removed by immersion in dilute HCl (for example, 5-10% by volume) at room
temperature, followed by brushing with mild detergent and through rinsing with water.
5.4.3 Fasteners, one alloy UNS N10276 (or similarly resistant alloy) fastener is required for each assembly. Each assembly
comprises a threaded bolt and nut plus two washers. The bolt length shall be sized to allow passage through the mouth of the
glassware described in 5.1.
5.5 Tools and Instruments:
5.5.1 A 6.35-mm ( ⁄4-in.) torque limiting nut driver is required for assembly of the Methods D and F crevice test specimen.
5.5.2 Low Power Microscope, (for example, 203 magnification) for pit detection.
5.5.3 NeedlePointDialDepthIndicatororFocusingMicroscope,todeterminethedepthofpittingorcrevicecorrosion,orboth.
5.5.4 Electronic Balance (optional), to determine specimen mass to the nearest 0.0001 g.
5.5.5 Camera (optional), to photographically record the mode and extent of any localized corrosion.
6. Ferric Chloride Test Solution
6.1 For Methods A and B, dissolve 100 g of reagent grade ferric chloride, FeCl ·6H O, in 900 mL of Type IV reagent water
3 2
(SpecificationD 1193)(about6 %FeCl bymass).Filterthroughglasswoolorfilterpapertoremoveinsolubleparticlesifpresent.
6.2 For Methods C, D, E, and D,F, dissolve 68.72 g of reagent grade ferric chloride, FeCl ·6H O in 600 mL of reagent water
3 2
andadd16mLofreagentgradeconcentrate
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:G48–03 Designation: G 48 – 03 (Reapproved 2009)
Standard Test Methods for
Pitting and Crevice Corrosion Resistance of Stainless
Steels and Related Alloys by Use of Ferric Chloride
Solution
ThisstandardisissuedunderthefixeddesignationG 48;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. 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 (seeTerminology G 15) 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 the standard. Other units are given in parentheses for information only.
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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
A 262 Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels
D 1193 Specification for Reagent Water
E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E 1338 Guide for the Identification of Metals and Alloys in Computerized Material Property Databases
G1 Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens
G15 Terminology Relating to Corrosion and Corrosion Testing
G46 Guide for Examination and Evaluation of Pitting Corrosion
G 107 Guide for Formats for Collection and Compilation of Corrosion Data for Metals for Computerized Database Input
3. Terminology
3.1 DefinitionDefinitions of Terms Specific to This Standard:
3.1.1 critical crevice temperature, n—the minimum temperature (°C) to produce crevice attack at least 0.025-mm (0.001-in.)
deep on the bold surface of the specimen beneath the crevice washer, edge attack ignored.
3.1.2 critical pitting temperature, n— the minimum temperature (°C) to produce pitting attack at least 0.025-mm (0.001-in.)
These test methods are under the jurisdiction of ASTM Committee G01 on Corrosion of Metals,Metals and are the direct responsibility of Subcommittee G01.05 on
Laboratory Corrosion Tests.
Current edition approved May 10, 2003.1, 2009. Published July 2003.May 2009. Originally approved in 1976. Last previous edition approved in 20002003 as G48–00.
G 48–03.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 01.03.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.
G 48 – 03 (2009)
deep on the bold surface of the specimen, edge attack ignored.
3.2 The terminology used herein, if not specifically defined otherwise, shall be in accordance with Terminology G 15.
Definitions provided herein and not given in Terminology G 15 are limited only to this standard.
4. 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). 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 MethodsA, 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 MethodsA, B, C, D, E, and F were designed to accelerate the time to initiate localized corrosion relative to most natural
environments.Consequently,thedegreeofcorrosiondamagethatoccursduringtestingwillgenerallybegreaterthanthatinnatural
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 be representative of the conditions of the actual piece from which the sample was taken.
NOTE 1—Grinding or pickling on stainless steel surfaces may destroy the passive layer. A 24-h air passivation after grinding or pickling is sufficient
to minimize these differences (8).
4.4.4 The procedures in Methods C, D, E and F for measuring critical pitting corrosion temperature and critical crevice
corrosion temperature have no bias because the values are defined only in terms of these test methods.
5. Apparatus
5.1 Glassware—Methods A, B, C, D, E, and F provide an option to use either wide mouth flasks or suitable sized test tubes.
Condensers are required for elevated temperature testing when solution evaporation may occur. Glass cradles or hooks also may
be required.
5.1.1 Flask Requirements, 1000-mLwide mouth. Tall form or Erlenmeyer flasks can be used. The mouth of the flask shall have
a diameter of about 40 mm (1.6 in.) to allow passage of the test specimen and the support.
5.1.2 Test Tube Requirements, the diameter of the test tube shall also be about 40 mm (1.6 in.) in diameter. If testing requires
use of a condenser (described below), the test tube length shall be about 300 mm (about 12 in.); otherwise, the length can be about
150 to 200 mm (about 6 in. to 8 in.).
5.1.3 Condensers, Vents and Covers :
5.1.3.1 Avarietyofcondensersmaybeusedinconjunctionwiththeflasksdescribedin5.1.1.Theseincludethecoldfinger-type
(see, for example, Practices A 262, Practice C) or Allihn type condensers having straight tube ends or tapered ground joints.
Straight end condensers can be inserted through a bored rubber stopper. Likewise, a simple U tube condenser can be fashioned.
NOTE 2—The use of ground joint condensers requires that the mouth of the flask have a corresponding joint.
5.1.3.2 U Tube Condensers, fitted through holes in an appropriate size rubber stopper can be used in conjunction with the
300-mm test tube described in 5.1.2.
5.1.3.3 Whenevaporationisnotasignificantproblem,flaskscanbecoveredwithawatchglass.Also,flasksaswellastesttubes
can be covered with loosely fitted stoppers or plastic or paraffin type wraps.
NOTE 3—Venting must always be considered due to the possible build up of gas pressure that may result from the corrosion process.
5.1.4 Specimen Supports:
5.1.4.1 One advantage of using test tubes is that specimen supports are not required. However, placement of the specimen does
create the possible opportunity for crevice corrosion to occur along the edge.
NOTE 4—See 14.2 concerning edge attack.
Annual Book of ASTM Standards, Vol 11.01.
The boldface numbers in parentheses refer to the list of references at the end of this standard.
G 48 – 03 (2009)
5.1.4.2 When using flasks, specimens can be supported on cradles or hooks. Cradles, such as those shown in Fig. 1, eliminate
the necessity for drilling a support hole in the test specimen. While the use of hooks requires that a specimen support hole be
provided, the hooks, as contrasted to the cradle, are easier to fashion. Moreover, they create only one potential crevice site whereas
multiple sites are possible with the cradle.
NOTE 5—A TFE-fluorocarbon cradle may be substituted for glass.
5.1.4.3 The use of supports for Methods B, D, and F crevice corrosion specimens is optional.
5.2 Water or Oil Bath, constant temperature.
5.2.1 For Methods A and B, the recommended test temperatures are 22 6 2°C or 50 6 2°C, or both.
5.2.2 For Methods C, D, E, and F, the bath shall have the capability of providing constant temperature between 0°C and 85°C
6 1°C.
5.3 Crevice Formers—Method B:
5.3.1 Cylindrical TFE-fluorocarbon Blocks, two for each test specimen. Each block shall be 12.7-mm (0.5 in.) in diameter and
12.7-mm high, with perpendicular grooves 1.6-mm (0.063 in.) wide and 1.6-mm deep cut in the top of each cylinder for retention
of the O-ring or rubber bands. Blocks can be machined from bar or rod stock.
5.3.2 Fluorinated Elastomers O-rings, or Rubber Bands, (low sulfur (0.02 % max)), two for each test specimen.
NOTE 6—It is good practice to use all O-rings or all rubber bands in a given test program.
5.3.2.1 O-rings shall be 1.75 mm (0.070 in.) in cross section; one ring with an inside diameter of about 20 mm (0.8 in.) and
one with an inside diameter of about 30 mm (1.1 in.). Rubber bands shall be one No. 12 (38-mm (1.5-in.) long) and one No. 14
(51-mm (2-in.) long).
NOTE 7—Rubber bands or O-rings can be boiled in water prior to use to ensure the removal of water-soluble ingredients that might affect corrosion.
5.4 Crevice Formers—Methods D and F:
5.4.1 A Multiple Crevice Assembly (MCA), consisting of two TFE-fluorocarbon segmented washers, each having a number of
grooves and plateaus, shall be used. The crevice design shown in Fig. 2 is one of a number of variations of the multiple crevice
assembly that is in use and commercially available.
5.4.2 Reuse of Multiple Crevice Assemblies, when assembled to the specified torque, the TFE-fluorocarbon segmented washers
should not deform during testing. Before reuse, each washer should be inspected for evidence of distortion and other damage. If
so affected, they should be discarded. In some cases, the crevice formers may become stained with corrosion products from the
tested alloy. Generally, this staining can be removed by immersion in dilute HCl (for example, 5-10% by volume) at room
temperature, followed by brushing with mild detergent and through rinsing with water.
Annual Book of ASTM Standards, Vol 14.02.
The sole source of supply of the apparatus known to the committee at this time is Metal Samples Co., Inc., P.O. Box 8, Route 1 Box 152, Munford, AL 36268. If you
are aware of alternative suppliers, please provide this information toASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible
technical committee, which you may attend.
FIG. 1 Examples of Glass Cradles that Can Be Used to Support the Specimen
G 48 – 03 (2009)
FIG. 2 TFE-fluorocarbon Crevice Washers
5.4.3 Fasteners, one alloy UNS N10276 (or similarly resistant alloy) fastener is required for each assembly. Each assembly
comprises a threaded bolt and nut plus two washers. The bolt length shall be sized to allow passage through the mouth of the
glassware described in 5.1.
5.5 Tools and Instruments:
5.5.1 A 6.35-mm ( ⁄4-in.) torque limiting nut driver is required for assembly of the Methods D and F crevice test specimen.
5.5.2 Low Power Microscope, (for example, 203 magnification) for pit detection.
5.5.3 NeedlePointDialDepthIndicatororFocusingMicroscope,todeterminethedepthofpittingorcrevicecorrosion,orboth.
5.5.4 Electronic Balance (optional), to determine specimen mass to the nearest 0.0001 g.
5.5.5 Camera (optional), to photographically record the mode and extent of any localized corrosion.
6. Ferric Chloride Test Solution
6.1 For Methods A and B, dissolve 100 g of reagent grade ferric chloride, FeCl ·6H O, in 900 mL of Type IV reagent water
3 2
(Specification D 1193) (about 6 % FeCl by mass). Filter through glass wool or filter paper to remove insoluble particles if present.
6.2 For Methods C, D, E, and F, dissolve 68.72 g of reagent grade ferric chloride, FeCl ·6H O in 600 mLof reagent water and
3 2
add 16 mL of reagent grade concentrated (36.5–38.0 %) hydrochloric acid (HCl). This will produce a solution containing about
6 % FeCl by mass and 1 % HCl resulting in a pH controlled environment over the test temperatures (9).
7. Test Specimens
7.1 Atestspecimen25by50mm(1by2in.)isrecommendedasastandardsize,althoughvariousshapesandsizescanbetested
bythismethod.Allspecimensinatestseriesshouldhavethesamedimensionswhencomparisonsaretobemade.Unlessend-grain
pitting is an integral part of the evaluation, the proportion of end-grain surface to specimen surface should be kept as small as
possible given the limitations of specimen sizes because of the susceptibility of end-grain surfaces to pitti
...
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