ASTM A967 - A 967M - 25 不锈钢零件化学钝化处理的标准规范

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Designation: A967/A967M −25
Standard Speciﬁcation for
Chemical Passivation Treatments for Stainless Steel Parts
1
This standard is issued under the ﬁxed designation A967/A967M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This speciﬁcation covers several different types of
chemical passivation treatments for stainless steel parts. It
includes recommendations and precautions for descaling,
cleaning, and passivation of stainless steel parts. It includes
several alternative tests, with acceptance criteria, for conﬁrma-
tion of effectiveness of such treatments for stainless steel parts.
1.2 Practices for the mechanical and chemical treatments of
stainless steel surfaces are discussed more thoroughly in
Practice A380/A380M.
1.3 Several alternative chemical treatments are deﬁned for
passivation of stainless steel parts. Appendix X1 and Appendix
X2 give some nonmandatory information and provides some
general guidelines regarding the selection of passivation treat-
ments appropriate to particular grades of stainless steel. This
speciﬁcation makes no recommendations regarding the suit-
ability of any grade, treatment, or acceptance criteria for any
particular application or class of applications.
1.4 The tests in this speciﬁcation are qualitative tests in-
tended to conﬁrm the effectiveness of passivation, particularly
with regard to the removal of contaminant iron and other
exogenous matter. These tests include the following practices:
1.4.1 Practice A—Water Immersion Test,
1.4.2 Practice B—High Humidity Test,
1.4.3 Practice C—Salt Spray Test,
1.4.4 Practice D—Copper Sulfate Test,
1.4.5 Practice E—Potassium Ferricyanide-Nitric Acid Test,
1.4.6 Practice F—Damp Cloth Test, and
1.4.7 Practice G—Boiling Water Immersion Test.
1.5 The values stated in either SI units or inch-pound units
are to be regarded separately as standard. The values stated in
each system are not necessarily exact equivalents; therefore, to
ensure conformance with the standard, each system shall be
used independently of the other, and values from the two
systems shall not be combined.
1.6 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.
1.7 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
A380/A380M Practice for Cleaning, Descaling, Pickling,
and Passivation of Stainless Steel Parts, Equipment, and
Systems
A941 Terminology Relating to Steel, Stainless Steel, Related
Alloys, and Ferroalloys
B117 Practice for Operating Salt Spray (Fog) Apparatus
B600 Guide for Descaling and Cleaning Titanium and Tita-
nium Alloy Surfaces
B912 Speciﬁcation for Passivation of Stainless Steels Using
Electropolishing
D1193 Speciﬁcation for Reagent Water
E2234 Practice for Sampling a Stream of Product by Attri-
butes Indexed by AQL
E2910 Guide for Preferred Methods for Acceptance of
Product
G48 Test Methods for Pitting and Crevice Corrosion Resis-
tance of Stainless Steels and Related Alloys by Use of
Ferric Chloride Solution
G61 Test Method for Conducting Cyclic Potentiodynamic
Polarization Measurements for Localized Corrosion Sus-
ceptibility of Iron-, Nickel-, or Cobalt-Based Alloys
G150 Test Method for Electrochemical Critical Pitting Tem-
perature Testing of Stainless Steels and Related Alloys
1
This speciﬁcation is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
A01.14 on Methods of Corrosion Testing.
Current edition approved Jan. 1, 2025. Published January 2025. Originally
approved in 1996. Last previous edition approved in 2017 as A967/A967M – 17.
DOI: 10.1520/A0967-25.
2
For referenced ASTM standards, visit the ASTM website, 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 website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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

2.2 Federal Speciﬁcation:
3
QQ-P-35C Passivation Treatments for Corrosion-Resistant
Steels
4
3. Terminology
3.1 Deﬁnitions:
3.1.1 For deﬁnitions of terms used in this standard, refer to
Terminology A941.
3.2 Deﬁnitions of Terms Speciﬁc to This Standard:
3.2.1 alloyed iron, n—iron that is inherent to the composi-
tion of the alloy, especially at the metal surface where it is
available to undergo oxidation.
3.2.1.1 Discussion—The removal of alloyed iron from the
surface of stainless steel will typically enhance the corrosion
resistance to some degree. “Oxidation” in the above context
refers to both conversion to iron oxide on the surface (corro-
sion) and the removal of iron from the surface by conversion
into ions released into the acid solution (passivation treatment).
3.2.2 contaminant iron, n—iron, especially nonstainless
steel, deposited onto a metal surface from a separate and
external source; also known as free iron.
3.2.2.1 Discussion—Contaminant iron is likely to corrode,
irrespective of the properties of the substrate material. Con-
taminant iron that is deeply embedded in the surface is often
more difficult to remove. Contaminant iron can be introduced
through many routes, including, but not limited to the follow-
ing: atmospheric deposition such as iron dust; use of blasting
media, grinding media, fabrication equipment, or other tooling
that has been used with or was in contact with nonstainless
steels; contact by steel hooks, chains, forks or tools; nearby
grinding or other work on nonstainless steels; residual iron
salts from pickling solutions; iron deposits in welds; embedded
iron; and iron oxide.
3.2.3 passivation, n—the chemical treatment of a stainless
steel with a nitric acid or citric acid solution, or other chemical
solutions or electrochemical treatments capable of producing
similar results, for the purpose of the removal of any combi-
nation of contaminant iron, alloyed iron, and possibly other
foreign matter from the surface, resulting in an increase of the
corrosion resistance of the surface via enabling the formation
of a better passive metal oxide ﬁlm.
3.2.3.1 Discussion—In the broadest sense, passivation is
any process through which a metal surface is rendered passive,
which is to say, inactive and resistant to further chemical
reactions, especially corrosion. The term passivation is com-
monly applied to several distinctly different operations or
processes relating to stainless steels. In order to avoid ambi-
guity in the setting of requirements, it is necessary to deﬁne
precisely the intended meaning of passivation in this standard.
In this speciﬁcation, passivation, unless otherwise speciﬁed, is
deﬁned as above. Some of the other various meanings associ-
ated with the term passivation that are in common usage
include the following:
3.2.3.2 The formation of the protective passive metal oxide
ﬁlm on a stainless steel, also called passivation in a more
general context, will occur spontaneously in air or other
oxygen-containing environments when the stainless steel sur-
face is free of oxide scale and exogenous matter. It was at one
time considered that an oxidizing treatment was necessary to
establish this passive metal oxide ﬁlm, but it is now accepted
that under this deﬁnition, stainless steels are autopassivating.
The presence of exogenous surface contamination, including
dirt, grease, contaminant iron from contact with steel tooling,
and so forth, may interfere with the formation of the passive
metal oxide ﬁlm. The cleaning of these contaminants from the
stainless steel surface will facilitate the spontaneous passiva-
tion by allowing the oxygen uniform access to the surface. The
passive metal oxide ﬁlm may be augmented by chemical
treatments that provide an oxidizing environment for the
stainless steel surface, for example the removal of alloyed iron
from the surface, or providing a rich oxygen source to
accelerate the formation of the passive metal oxide ﬁlm after
iron has been removed from the surface. However, such
chemical treatment is generally not necessary for some forma-
tion of the passive metal oxide ﬁlm.
3.2.3.3 In the case of stainless steels with additions of sulfur
for the purpose of improved machinability, the removal of
sulﬁde inclusions from the surface of the metal should also be
included as part the overall passivation process, such as a
pretreatment cleaning step. (See X2.5).
3.2.3.4 Chemical treatments providing a rich oxygen
source, such as sodium dichromate or peroxide solutions, may
facilitate the more rapid formation of the passive metal oxide
ﬁlm on a stainless steel surface already free of scale or foreign
matter. Such treatments, also sometimes called passivation in
common usage, are designated as post-cleaning treatments in
this speciﬁcation in order to distinguish them from chemical
treatments capable of removing iron from the surface of
stainless steels.
3.2.3.5 Passivation does not indicate the separate processes
of descaling or pickling, although descaling or pickling may be
necessary before passivation can be effective (see Practice
A380/A380M). Chemical treatments capable of removing heat
tint or oxide scale from stainless steel and capable of dissolving
the stainless steel itself, typically called pickling, are substan-
tially more aggressive than treatments used for passivation, as
deﬁned in 3.2.3. The surface of stainless steel that has been
pickled is free of scale, contaminant iron, and exogenous
foreign matter, and does not typically require a separate
treatment for passivation as deﬁned in 3.2.3. The passivation
process deﬁned in 3.2.3.2 will occur without further chemical
treatment, but may be augmented and improved by the passi-
vation treatment deﬁned in 3.2.3 or the post-cleaning treat-
ments deﬁned in 3.2.3.4. A combination of pickling and
passivation treatments, especially a nitric acid treatment per
Section 6, can also produce brightening of the surface, but
generally not with the brilliant luster obtained by polishing.
3.2.3.6 Electrochemical treatments, including electropick-
ling and electropolishing capable of removing heat tint or oxide
scale from stainless steel and capable of dissolving the stainless
steel itself, are substantially more aggressive than treatments
3
Available from Superintendent of Documents, U.S. Government Printing
Office, Washington, DC 20402.
4
In accordance with QQ-P-35C Notice 3, September 11, 1998, Speciﬁcation
QQ-P-35C is cancelled and Speciﬁcation A967/A967M should be used in its place
for DoD activities other than aerospace applications.
A967/A967M − 25
2

used for passivation, as deﬁned in 3.2.3. The surface of
stainless steel resulting from these treatments is free of scale,
contaminant iron, and exogenous foreign matter, and does not
require a separate treatment for passivation as deﬁned in 3.2.3.
The passivation process deﬁned in 3.2.3.2 will occur without
further chemical treatment, but may be augmented and im-
proved by the passivation treatment deﬁned in 3.2.3 or the
post-cleaning treatments deﬁned in 3.2.3.4. Statements regard-
ing chemical treatments, unless otherwise speciﬁed, are taken
to include electrochemical treatments.
4. Ordering Information
4.1 This speciﬁcation was written for the purpose of pro-
viding an alternative to United States Federal Speciﬁcation
QQ-P-35C. Determination of the suitability of this speciﬁca-
tion for that purpose is the responsibility of the purchaser.
4.2 Unless speciﬁed by the purchaser, the chemical treat-
ment applied to the stainless steel parts shall be selected by the
supplier from among the listed passivation treatments. (See
5.1.)
4.3 Unless speciﬁed by the purchaser, the test practice(s)
and test frequency or sampling plan applied to the stainless
steel parts shall be selected by the supplier from among the
listed test practices. (See Section 13.)
4.4 The purchaser may also specify additional requirements,
including the following:
4.4.1 Post-cleaning treatments. (See Section 10.)
4.4.2 Availability of reports and records. (See 5.2.2 and
Section 17.)
4.4.3 Inclusion or exemption of areas with identiﬁcation
markings from test requirements (see 14.10.)
5. Materials and Preparation for Passivation Treatments
5.1 The passivation treatments shall be of one or more of the
following types. The effectiveness of a particular treatment for
a particular grade of stainless steel in a particular application is
demonstrated by meeting the speciﬁed testing requirements:
5.1.1 Treatments in nitric acid solutions (see Section 6),
5.1.2 Treatments in citric acid solutions (see Section 7),
5.1.3 Treatments in other chemical solutions, including
electrochemical treatments (see Section 8),
5.1.4 Rinsing and neutralization (see Section 9), and
5.1.5 Post-cleaning treatments (see Section 10).
5.2 Materials:
5.2.1 The chemicals used for passivation treatments shall
produce passivated surfaces that meet the requirements of one
or more of the tests of this speciﬁcation. Attention shall be
given to maintaining adequate volume appropriate to the size
and amount of stainless steel to be treated, as well as
concentration and temperature control appropriate to the se-
lected treatment. (See Note 1.)
NOTE 1—Attention should also be given to maintaining good cleanli-
ness of the passivation solution to ensure the production of acceptable
surfaces that meet the requirements.
5.2.2 The supplier shall maintain a record with regard to
concentration and temperature of the passivation solution
sufficient to demonstrate that the speciﬁed passivation condi-
tions were maintained for each lot of stainless steel parts
processed. Such records shall be available for inspection when
speciﬁed in the purchase order. The supplier is not required by
this speciﬁcation to reveal the precise composition of propri-
etary chemical mixtures but shall maintain a unique identiﬁ-
cation of the mixture that will ensure its accurate representation
for subsequent use.
5.2.3 The supplier shall be responsible for the safe disposal
of all material generated by this process.
5.3 Preparation for Passivation Treatments:
5.3.1 Any pretreatment methods and procedures used prior
to the passivation treatment, including mechanical and chemi-
cal methods, singly or in combination, for descaling and
pickling, shall be in accordance with Practice A380/A380M.
5.3.2 The resulting pretreated surface shall be substantially
free of oil, grease, rust, scale, and other foreign matter.
5.3.3 When the ﬁnal pretreatment of a part includes pickling
of the entire surface of the part, no further passivation
treatment is required prior to testing of the surface unless
speciﬁed by the purchaser.
6. Treatments in Nitric Acid Solutions
6.1 Passivation Treatment:
6.1.1 Stainless steel parts shall be treated in one of the
following aqueous solutions and maintained within the speci-
ﬁed temperature range for the speciﬁed time. Where immersion
is impractical, other methods of maintaining contact between
the stainless steel surface and the solution within the speciﬁed
temperature range for the speciﬁed time may be used.
6.1.1.1 Nitric 1—The solution shall contain 20 to 25 volume
percent of nitric acid and 2.5 60.5 weight percent of sodium
dichromate dihydrate. The parts shall be immersed for a
minimum of 20 min at a temperature in the range from 50 °C
to 55 °C [120 °F to 130 °F].
6.1.1.2 Nitric 2—The solution shall contain 20 to 45 volume
percent of nitric acid. The parts shall be immersed for a
minimum of 30 min at a temperature in the range from 20 °C
to 30 °C [70 °F to 90 °F].
6.1.1.3 Nitric 3—The solution shall contain 20 to 25 volume
percent of nitric acid. The parts shall be immersed for a
minimum of 20 min at a temperature in the range from 50 °C
to 60 °C [120 °F to 140 °F].
6.1.1.4 Nitric 4—The solution shall contain 45 to 55 volume
percent of nitric acid. The parts shall be immersed for a
minimum of 30 min at a temperature in the range from 50 °C
to 55 °C [120 °F to 130 °F].
6.1.1.5 Nitric 5—Other combinations of temperature, time,
and concentration of nitric acid, with or without other
chemicals, including accelerants, inhibitors, or proprietary
solutions, capable of producing parts that pass the speciﬁed test
requirements.
6.1.1.6 Nitric acid to be used in the formulations described
above shall be the typical commercially available concentrated
aqueous solution of nitric acid containing 61.0 to 68.2 weight
percent of HNO
3
(also referred to as 42° Baumé).
6.2 Water Rinse—Immediately after removal from the pas-
sivating solution, the parts shall be thoroughly rinsed, using
stagnant, countercurrent, or spray washes, singly or in
A967/A967M − 25
3

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摘要：

ASTM A967 - A 967M - 25 是全球广泛引用的不锈钢零件化学钝化处理标准规范，最新版本于2025年发布。该标准详细规定了通过化学方法去除不锈钢表面游离铁、其他污染物及焊接氧化层，从而形成均匀、耐腐蚀钝化膜的技术要求与测试方法。适用于奥氏体、铁素体、马氏体及沉淀硬化型不锈钢零件的钝化处理，涵盖硝酸基与柠檬酸基两大类化学溶液工艺，并明确了浸泡时间、温度、后续清洗及中和步骤。本标准还提供了多种验收测试程序，包括水浸测试、硫酸铜测试、铁氰化钾测试及高湿度暴露测试，确保钝化层完整且无残留

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