ASTM A967-05e1
(Specification)Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts
Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts
ABSTRACT
This specification covers several different types of chemical passivation treatments for stainless steel parts. The treatments are the following: immersion treatment using nitric acid solutions, immersion treatment using citric acid solution, and electrochemical treatment. Immediately after the removal from the passivating solution, the parts shall be thoroughly rinsed, using stagnant, countercurrent, or spray washes, singly or in combination, with or without a separate chemical treatment for neutralization of the passivation media. The chemical reactions of the passivating media on the surface of the stainless steel shall be stopped by rinsing of the stainless steel part, with or without a separate neutralization treatment. A chemical treatment shall be applied which will accelerate the formation of the passive film on a chemically clean stainless steel surface. The passivated parts shall exhibit a chemically clean surface and shall, on visual inspection, show no etching, pitting, or frosting. The following tests shall be performed on each lot of stainless steel parts: water immersion test, high humidity test, salt spray test, copper sulfate test, and potassium ferricyanide-nitric acid test. A free iron test shall be used for the detection of free iron on the surface of stainless steel.
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 confirmation 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 A 380.
1.3 Several alternative chemical treatments are defined for passivation of stainless steel parts. Appendix X1 gives some nonmandatory information and provides some general guidelines regarding the selection of passivation treatment appropriate to particular grades of stainless steel. It makes no recommendations regarding the suitability of any grade, treatment, or acceptance criteria for any particular application or class of applications.
1.4 The tests in this specification are intended to confirm the effectiveness of passivation, particularly with regard to the removal of free 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, and
1.4.6 Practice F - Free Iron Test.
1.5 The values stated in inch-pound units are to be regarded as the standard. The SI units given in parentheses are for information only.
The following precautionary caveat pertains only to the test method portions, Sections 14 through 18 of this specification: 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: A967 – 05
Standard Specification for
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Chemical Passivation Treatments for Stainless Steel Parts
This standard is issued under the fixed designation A967; 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 Department of Defense.
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´ NOTE—Section 6.1.1.1 was editorially corrected in July 2007.
1. Scope* concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and
1.1 This specification covers several different types of
health practices and determine the applicability of regulatory
chemical passivation treatments for stainless steel parts. It
limitations prior to use.
includes recommendations and precautions for descaling,
cleaning, and passivation of stainless steel parts. It includes
2. Referenced Documents
several alternative tests, with acceptance criteria, for confirma-
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2.1 ASTM Standards:
tion of effectiveness of such treatments for stainless steel parts.
A380 Practice for Cleaning, Descaling, and Passivation of
1.2 Practices for the mechanical and chemical treatments of
Stainless Steel Parts, Equipment, and Systems
stainless steel surfaces are discussed more thoroughly in
B117 Practice for Operating Salt Spray (Fog) Apparatus
Practice A380.
B254 Practice for Preparation of and Electroplating on
1.3 Several alternative chemical treatments are defined for
Stainless Steel
passivation of stainless steel parts. Appendix X1 gives some
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2.2 Federal Specification:
nonmandatory information and provides some general guide-
QQ-P-35C Passivation Treatments for Corrosion-Resistant
lines regarding the selection of passivation treatment appropri-
Steels
ate to particular grades of stainless steel. It makes no recom-
mendations regarding the suitability of any grade, treatment, or
3. Terminology
acceptance criteria for any particular application or class of
3.1 Definition of Term Specific to This Standard—It is
applications.
necessary to define which of the several commonly used
1.4 Thetestsinthisspecificationareintendedtoconfirmthe
definitions of the term passivation will be used in this
effectiveness of passivation, particularly with regard to the
specification. (See Discussion.)
removal of free iron and other exogenous matter. These tests
3.1.1 Discussion—Stainlesssteelsareautopassivatinginthe
include the following practices:
sense that the protective passive film is formed spontaneously
1.4.1 Practice A—Water Immersion Test,
on exposure to air or moisture. The presence of exogenous
1.4.2 Practice B—High Humidity Test,
surface contamination, including dirt, grease, free iron from
1.4.3 Practice C—Salt Spray Test,
contact with steel tooling, and so forth, may interfere with the
1.4.4 Practice D—Copper Sulfate Test,
formation of the passive film. The cleaning of these contami-
1.4.5 Practice E—Potassium Ferricyanide–NitricAcidTest,
nants from the stainless steel surface will facilitate the spon-
and
taneous passivation by allowing the oxygen uniform access to
1.4.6 Practice F—Free Iron Test.
the surface. The passive film may be augmented by chemical
1.5 The values stated in inch-pound units are to be regarded
treatments that provide an oxidizing environment for the
as the standard. The SI units given in parentheses are for
stainless steel surface.
information only.
3.1.1.1 In this specification, passivation, unless otherwise
1.6 The following precautionary caveat pertains only to the
specified, is defined as the chemical treatment of a stainless
test method portions, Sections 14 through 18 of this specifica-
steel with a mild oxidant, such as a nitric acid solution, for the
tion: This standard does not purport to address all of the safety
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This specification is under the jurisdiction of ASTM Committee A01 on Steel, For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
A01.14 on Methods of Corrosion Testing. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Sept. 1, 2005. Published September 2005. Originally the ASTM website.
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approved in 1996. Last previous edition approved in 2001 as A967 – 01 . DOI: Available from Superintendent of Documents, U.S. Government Printing
10.1520/A0967-05E01. Office, Washington, DC 20402.
*A Summary of Changes section appears at the end of this standard.
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