ASTM G59-97e1

Standard Test Method for Conducting Potentiodynamic Polarization Resistance Measurements

SCOPE
1.1 This test method describes an experimental procedure for polarization resistance measurements which can be used for the calibration of equipment and verification of experimental technique. The test method can provide reproducible corrosion potentials and potentiodynamic polarization resistance measurements.
1.2 This test method 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.

General Information

• Status: Historical
• Publication Date: 09-Dec-1997
• Technical Committee: G01 - Corrosion of Metals
• Drafting Committee: G01.11 - Electrochemical Measurements in Corrosion Testing

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: G 59 – 97
Standard Test Method for
Conducting Potentiodynamic Polarization Resistance
1
Measurements
This standard is issued under the fixed designation G 59; 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 (e) indicates an editorial change since the last revision or reapproval.
1
e NOTE—Note 2 in Section 6.4 was updated editorially August 2002.
1. Scope 3.2 Polarization resistance can be related to the rate of
general corrosion for metals at or near their corrosion potential,
1.1 This test method describes an experimental procedure
E . Polarization resistance measurements are an accurate and
corr
for polarization resistance measurements which can be used for
rapid way to measure the general corrosion rate. Real time
the calibration of equipment and verification of experimental
corrosion monitoring is a common application. The technique
technique. The test method can provide reproducible corrosion
can also be used as a way to rank alloys, inhibitors, and so forth
potentials and potentiodynamic polarization resistance mea-
in order of resistance to general corrosion.
surements.
3.3 In this test method, a small potential scan, DE(t), defined
1.2 This test method does not purport to address all of the
with respect to the corrosion potential (DE=E–E ), is
safety concerns, if any, associated with its use. It is the corr
applied to a metal sample. The resultant currents are recorded.
responsibility of the user of this standard to establish appro-
The polarization resistance, R , of a corroding electrode is
priate safety and health practices and determine the applica- P
defined from Eq 1 as the slope of a potential versus current
bility of regulatory limitations prior to use.
4
density plot at i =0 (1-4):
2. Referenced Documents
]DE
R 5 (1)
S D
p
] i
2.1 ASTM Standards:
i50, dE/dt→0
G 3 Practice for Conventions Applicable to Electrochemical
The current density is given by i. The corrosion current
2
Measurements in Corrosion Testing
density, i , is related to the polarization resistance by the
corr
G 5 Test Method for Making Potentiostatic and Potentiody-
Stern-Geary coefficient, B. (3),
2
namic Anodic Polarization Measurements
B
6
G 102 Practice for Calculation of Corrosion Rates and
i 5 10 (2)
corr
R
2 p
Related Information from Electrochemical Measurements
2 2
The dimension of R is ohm-cm , i is muA/cm , and B is
2.2 Adjunct: p corr
in V. The Stern-Geary coefficient is related to the anodic, b ,
a
Samples of the Standard AISI Type 430 Stainless Steel (UNS
3
and cathodic, b , Tafel slopes as per Eq 3.
S43000) c
b b
a c
3. Significance and Use B 5 (3)
2.303~b 1 b !
a c
3.1 This test method can be utilized to verify the perfor-
The units of the Tafel slopes are V. The corrosion rate, CR,
mance of polarization resistance measurement equipment in-
in mm per year can be determined from Eq 4 in which EW is
cluding reference electrodes, electrochemical cells, poten-
the equivalent weight of the corroding species in grams and r
tiostats, scan generators, measuring and recording devices. The 3
is the density of the corroding material in g/cm .
test method is also useful for training operators in sample
i EW
corr
–3
preparation and experimental techniques for polarization resis-
CR 5 3.27 3 10 (4)
r
tance measurements.
Refer to Practice G 102 for derivations of the above equa-
tions and methods for estimating Tafel slopes.
1
This practice is under the jurisdiction of ASTM Committee G–1 on Corrosion
3.4 The test method may not be appropriate to measure
of Metals, and is the direct responsibility of Subcommittee G 01.11 on Electro-
polarization resistance on all materials or in all environments.
chemical Measurements in Corrosion Testing.
Current edition approved Dec. 10, 1997. Published February 1998. Originally
published as G 59 – 78. Last previous edition G 59 – 91.
2 4
Annual Book of ASTM Standards, Vol 03.02. The boldface numbers in parentheses refer to the list of references at the end of
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Available from ASTM Headquarters. Order PCN 12-700050-00. this standard.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
G59–97
See 8.2 for a discussion of method biases arising from solution started at least 30 min before specimen immersion. The purge
resistance and electrode capacitance. continues throughout the test.
6.3 The working electrode should be prepared as detailed in
4. A
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