ASTM G31 - 21 (2025) 金属的实验室浸没腐蚀试验的标准指南

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Designation: NACE TM0169/G31 −21 (Reapproved 2025)
Standard Guide for
Laboratory Immersion Corrosion Testing of Metals
1
This standard is issued under the ﬁxed designation NACE TM0169/G31; 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 guide covers and describes the factors that inﬂu-
ence laboratory immersion corrosion tests, particularly mass
loss tests. These factors include apparatus, sampling, test
specimen, test conditions (test solution composition,
temperature, gas sparging, ﬂuid motion, solution volume,
method of supporting test specimens, duration of test), methods
of cleaning test specimens, interpretation of results, and
calculation of corrosion rates. This guide also emphasizes the
importance of recording all pertinent data and provides a
checklist for reporting test data.
1.2 The speciﬁc evaluation of localized attack, environmen-
tally assisted cracking, and effects of solution ﬂow are not
within the scope of this guide.
1.3 This guide is intended to be used by those designing
laboratory immersion tests who may not be familiar with all of
the variables to consider and the pitfalls that could be encoun-
tered when designing and conducting this kind of testing. It
should be used as a reference to ensure that the test will allow
generation of data relevant to the application with the mini-
mum of interferences.
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 appro-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
2
A262 Practices for Detecting Susceptibility to Intergranular
Attack in Austenitic Stainless Steels
D1193 Speciﬁcation for Reagent Water
E8/E8M Test Methods for Tension Testing of Metallic Ma-
terials
E300 Practice for Sampling Industrial Chemicals
G1 Practice for Preparing, Cleaning, and Evaluating Corro-
sion Test Specimens
G28 Test Methods for Detecting Susceptibility to Inter-
granular Corrosion in Wrought, Nickel-Rich, Chromium-
Bearing Alloys
G34 Test Method for Exfoliation Corrosion Susceptibility in
2XXX and 7XXX Series Aluminum Alloys (EXCO Test)
G46 Guide for Examination and Evaluation of Pitting Cor-
rosion
G48 Test Methods for Pitting and Crevice Corrosion Resis-
tance of Stainless Steels and Related Alloys by Use of
Ferric Chloride Solution
G66 Test Method for Visual Assessment of Exfoliation
Corrosion Susceptibility of 5XXX Series Aluminum Al-
loys (ASSET Test)
G67 Test Method for Determining the Susceptibility to
Intergranular Corrosion of 5XXX Series Aluminum Al-
loys by Mass Loss After Exposure to Nitric Acid (NAMLT
Test)
G71 Guide for Conducting and Evaluating Galvanic Corro-
sion Tests in Electrolytes
G78 Guide for Crevice Corrosion Testing of Iron-Base and
Nickel-Base Stainless Alloys in Seawater and Other
Chloride-Containing Aqueous Environments
G82 Guide for Development and Use of a Galvanic Series
for Predicting Galvanic Corrosion Performance
G107 Guide for Formats for Collection and Compilation of
Corrosion Data for Metals for Computerized Database
Input
1
This guide is under the jurisdiction of NACE/ASTM Committee J01, Joint
Committee on Corrosion, and is the direct responsibility of Subcommittee J01.01,
Working Group on Laboratory Immersion Tests.
Current edition approved May 1, 2025. Published May 2025. Originally
approved in 1972. Last previous ASTM edition approved in 2021 as G31 – 21.
NACE edition originally approved in 1969. Last previous NACE edition approved
in 2021 as TM0169-2021. DOI: 10.1520/G0031-21R25.
2
For referenced ASTM standards, visit the ASTM Web site, www.astm.org, or
contact ASTM Customer Service at www.astm.org/contact. For Annual Book of
ASTM Standards volume information, refer to the standard’s Document Summary
page on the ASTM Web site. For NACE standards, visit the NACE Web site,
www.nace.org, or contact NACE First Service at ﬁrstservice@nace.org.
© NACE International/ASTM International 2025 – All rights reserved
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.
1

G108 Test Methods for Electrochemical Reactivation (EPR)
for Detecting Sensitization of AISI Type 304 and 304L
Stainless Steels
G110 Practice for Evaluating Intergranular Corrosion Resis-
tance of Heat Treatable Aluminum Alloys by Immersion
in Sodium Chloride + Hydrogen Peroxide Solution
G112 Guide for Conducting Exfoliation Corrosion Tests in
Aluminum Alloys
G116 Practice for Conducting Wire-on-Bolt Test for Atmo-
spheric Galvanic Corrosion
G135 Guide for Computerized Exchange of Corrosion Data
for Metals (Withdrawn 2023)
3
G170 Guide for Evaluating and Qualifying Oilﬁeld and
Reﬁnery Corrosion Inhibitors in the Laboratory
G184 Practice for Evaluating and Qualifying Oil Field and
Reﬁnery Corrosion Inhibitors Using Rotating Cage
G185 Practice for Evaluating and Qualifying Oil Field and
Reﬁnery Corrosion Inhibitors Using the Rotating Cylinder
Electrode
2.2 NACE/ASTM Standard:
2
G193 Terminology and Acronyms Relating to Corrosion
2.3 NACE International Standard:
2
SP0690 Standard Format for Collection and Compilation of
Data for Computerized Material Corrosion Resistance
Database Input
2.4 International Organization for Standardization (ISO)
Standards:
4
ISO 3651-1 Determination of resistance to intergranular
corrosion of stainless steels – Part 1: Austenitic and
ferritic-austenitic (duplex) stainless steels – Corrosion test
in nitric acid medium by measurement of loss in mass
(Huey test)
ISO 3651-2 Determination of resistance to intergranular
corrosion of stainless steels – Part 2: Ferritic, austenitic
and ferritic-austenitic (duplex) stainless steels – Corrosion
test in media containing sulfuric acid
ISO 6509 Corrosion of metals and alloys – Determination of
dezinciﬁcation resistance of brass
ISO 8407 Corrosion of metals and alloys – Removal of
corrosion products from corrosion test specimens
ISO 8993 Anodizing of aluminum and its alloys – Rating
system for the evaluation of pitting corrosion – Chart
method
ISO 8994 Anodizing of aluminum and its alloys – Rating
system for the evaluation of pitting corrosion – Grid
method
ISO 9400 Nickel-based alloys – Determination of resistance
to intergranular corrosion
ISO 11463 Corrosion of metals and alloys – Guidelines for
the evaluation of pitting corrosion
ISO 11845 Corrosion of metals and alloys – General prin-
ciples for corrosion testing
ISO 11846 Corrosion of metals and alloys – Determination
of resistance to intergranular corrosion of solution heat-
treatable aluminum alloys
ISO 11881 Corrosion of metals and alloys – Exfoliation
corrosion testing of aluminum alloys
3. Terminology
3.1 For deﬁnitions of terms used in this guide, see NACE/
ASTM Terminology G193.
4. Signiﬁcance and Use
4.1 Corrosion testing by its very nature precludes complete
standardization. This standard, rather than a standardized
procedure, is presented as a guide so that some of the pitfalls
of such testing may be avoided.
4.2 Experience has shown that all metals and alloys do not
respond alike to the many factors that affect corrosion and that
accelerated corrosion tests give indicative results only, or may
even be entirely misleading. It is impractical to propose an
inﬂexible standard laboratory corrosion testing procedure for
general use, except for material qualiﬁcation tests where
standardization is required. One purpose for this guide is to
promote better correlation of results in the future and the
reduction of conﬂicting reports through a more detailed record-
ing of meaningful factors and conditions.
4.3 In designing any corrosion test, consideration should be
given to the various factors discussed in this guide, because
these factors have been found to affect the results obtained.
5. Factors Affecting Corrosion Behavior
5.1 The methods and procedures described herein represent
the best current practices for conducting laboratory immersion
corrosion tests as developed by corrosion specialists in the
process industries. For proper interpretation of the results
obtained, the speciﬁc inﬂuence of one or more of the following
variables should be considered.
5.1.1 Metal specimens immersed in a speciﬁc hot liquid
may not corrode at the same rate or in the same manner as in
equipment where the metal acts as a heat transfer medium in
heating or cooling the liquid. If the inﬂuence of heat transfer
effects is speciﬁcally of interest, specialized procedures (in
which the corrosion specimen serves as a heat transfer agent)
shall be employed.
5.1.2 In laboratory immersion tests, the motion of the
environment relative to the specimens will normally be pro-
vided by convection currents, gas sparging, or boiling. If the
speciﬁc effects of ﬂuid ﬂow are to be studied, special tech-
niques shall be employed to create and control the relative
motion between the environment and the test specimens. This
may be accomplished by either moving the environment as
through a tube or mechanical stirrer or by moving the speci-
mens as by rotation.
5.1.3 The behavior of certain metals and alloys may be
profoundly inﬂuenced by the presence of dissolved oxygen. If
this is a factor to be considered in a speciﬁc test, the solution
should be air saturated at 1 atm or de-aerated, as appropriate.
5.1.4 In some cases, the rate of corrosion may be governed
by other minor constituents in the solution, in which case they
3
The last approved version of this historical standard is referenced on
www.astm.org.
4
Available from International Organization for Standardization (ISO), ISO
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
Geneva, Switzerland, http://www.iso.org.
NACE TM0169/G31 − 21 (2025)
2© NACE International/ASTM International 2025 – All rights reserved

will have to be continually or intermittently replenished by
changing the solution in the test.
5.1.5 Corrosion products may have undesirable effects on a
chemical product. The amount of possible contamination can
sometimes be estimated from the loss in mass of the specimen
or from the changes in the chemical composition of the test
environment. This is discussed in more detail in 9.8.3.
5.1.6 Corrosion products from the specimen may inﬂuence
the corrosion rate of the metal itself or of different metals
exposed at the same time. For example, the accumulation of
cupric ions in the testing of copper alloys in intermediate
strengths of sulfuric acid will accelerate the corrosion of
copper alloys, as compared to the rates that would be obtained
if the corrosion products were continually removed. It may be
necessary to expose only alloys of the same general type in the
same testing apparatus unless it is known that no interactions
will occur.
5.1.7 Specimen corrosion testing is frequently designed to
investigate general corrosion only. There are a number of other
forms of corrosion of which one shall be aware in the design
and interpretation of corrosion tests.
5.1.7.1 Galvanic corrosion may be investigated by special
devices that couple one specimen to another in electrical
contact. The behavior of the specimens in this galvanic couple
is compared with that of insulated specimens exposed on the
same holder. It should be observed, however, that galvanic
corrosion can be greatly affected by the area ratios of the
respective metals, the separation between the metals, and the
conductivity of the electrolyte. The coupling of corrosion
specimens then yields only qualitative results, as a particular
specimen reﬂects only the relationship between these two
metals at the particular area ratio involved. Galvanic corrosion
testing is further discussed in ASTM Guide G71, ASTM Guide
G82, and ASTM Practice G116.
5.1.7.2 Crevice corrosion or concentration cell corrosion
may occur where the metal surface is partially blocked from
the corroding liquid as under a spacer or supporting hook. It is
necessary to evaluate this localized corrosion separately from
the overall mass loss. Crevice corrosion testing is further
discussed in ASTM Test Methods G48 and ASTM Guide G78.
5.1.7.3 Selective corrosion at the grain boundaries (for
example, intergranular corrosion of sensitized austenitic stain-
less steels) will not be readily observable in mass loss
measurements unless the attack is severe enough to cause grain
dropping, and often requires microscopic examination of the
specimens after exposure. This type of corrosion may also
result in loss of strength or ductility of materials. Such losses
can be evaluated by mechanical property determinations before
and after exposure to the test environment. Testing for selective
corrosion is further discussed in ASTM Practices A262 and
G110, ASTM Test Methods G28,G34,G66,G67,G108, and
ASTM Guide G112 and ISO 3651-1, ISO 3651-2, ISO 9400,
ISO 11846, and ISO 11881.
5.1.7.4 Dealloying or “parting” corrosion is a condition in
which one constituent is selectively removed from an alloy, as
in the dezinciﬁcation of brass or the graphitization of cast iron.
Close attention and a more sophisticated evaluation than a
simple mass loss measurement are required to detect this
phenomenon. Dealloying testing is further discussed in ISO
6509.
5.1.7.5 Certain metals and alloys are subject to a highly
localized type of attack called pitting corrosion. This cannot be
evaluated by mass loss alone. Pitting is a statistical phenom-
enon and the incidence of pitting may be directly related to the
area of metal exposed. For example, a small specimen is not as
prone to exhibit pitting as a large one and it is possible to miss
the phenomenon altogether in the corrosion testing of certain
alloys, such as the AISI Type 300 series stainless steels in
chloride-containing environments. Pitting testing is further
discussed in ASTM Guide G46, ASTM Test Methods G48, and
ISO 8993, ISO 8994, and ISO 11463.
5.1.7.6 Most metals and alloys are subject to environmen-
tally assisted cracking under some circumstances. This crack-
ing occurs under conditions of applied or residual tensile stress,
and it may or may not be visible to the unaided eye or upon
casual inspection. A metallographic examination may conﬁrm
the presence of environmentally assisted cracking. This usually
occurs with no signiﬁcant loss in mass of the test specimen,
although certain refractory metals are an exception to these
observations. Generally, if cracking is observed on the
specimen, it can be taken as positive indication of
susceptibility, whereas failure to exhibit this phenomenon
means that it did not occur under the duration and speciﬁc
conditions of the test. Separate and special techniques are
employed for the speciﬁc evaluation of the susceptibility of
metals and alloys to environmentally assisted cracking. Mul-
tiple standards from many different organizations are available
to describe stress-corrosion cracking tests.
5.2 The use of welded specimens is sometimes desirable,
because some welds may be cathodic or anodic to the parent
metal and may affect the corrosion rate.
5.2.1 The heat-affected zone is also of importance but
should be studied separately because welds on test specimens
may not adequately reproduce heat input or size effects of
full-size vessels.
5.2.2 Corrosion of a welded specimen is normally localized
and not representative of the entire surface and therefore
separate thickness losses should be determined in the weld
metal, heat-affected zone, and base metal.
5.2.3 A complete discussion of corrosion testing of welded
specimens or the effect of heat treatment on the corrosion
resistance of a metal is not within the scope of this guide.
However, important factors to be considered include the
welding technique to be used, the ﬁller metal chemistry, and
whether the weld will be ground smooth, cleaned, passivated,
or left as-welded.
5.3 Cast and wrought alloys considered equivalent often
have somewhat different chemical composition and metallur-
gical structure, resulting in different corrosion resistances in
identical service conditions. Therefore, caution should be used
in selecting representative test materials.
5.4 Additional discussion of testing considerations is con-
tained in ISO 11845.
NACE TM0169/G31 − 21 (2025)
3
© NACE International/ASTM International 2025 – All rights reserved

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摘要：

ASTM G31 - 21 (2025) 是国际公认的金属实验室浸没腐蚀试验标准指南，为在实验室条件下通过全浸或部分浸没方式评估金属材料耐腐蚀性能提供统一、可重复的操作框架。该指南详细规定了试验装置设计、试样制备与尺寸要求、溶液体积与成分控制、浸泡周期选择、温度与通气条件管理、试验后清洗与质量损失测定方法，以及腐蚀速率计算和结果报告规范。其核心价值在于通过标准化流程减少变量干扰，使不同实验室或不同批次间的腐蚀数据具有可比性，适用于材料筛选、工艺质量评估、腐蚀机理研究及寿命预测等场景。标准同时强调

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