ASTM B912-00
(Specification)Standard Specification for Passivation of Stainless Steels Using Electropolishing
Standard Specification for Passivation of Stainless Steels Using Electropolishing
SCOPE
1.1 This specification covers the passivation of stainless steel alloys in the 200 (UNS2XXXX), 300 (UNS3XXXX), and 400 (UNS4XXXX) series, and the precipitation-hardened alloys, using electropolishing procedures.
Note 1--Surface passivation occurs simultaneously with electropolishing under proper operating conditions. The quality of passivation will depend on the type of stainless steel, the formulation of the electropolishing solution, and the conditions of operation. Free iron on the surface of the stainless steel is removed resulting in improved corrosion resistance. Surface smoothing obtained by electropolishing will also improve corrosion resistance. Electropolishing will also remove heat tint and oxide scale.
1.2 This specification may involve hazardous materials, operations, and equipment. This specification 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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Standards Content (Sample)
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Designation: B 912 – 00
Standard Specification for
Passivation of Stainless Steels Using Electropolishing
This standard is issued under the fixed designation B 912; 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. Scope Finishes—Sampling Procedures for Inspection by At-
tributes
1.1 This specification covers the passivation of stainless
ISO 9227 Corrosion Tests in Artificial Atmospheres—Salt
steel alloys in the 200 (UNS2XXXX), 300 (UNS3XXXX), and
Spray Tests
400 (UNS4XXXX) series, and the precipitation-hardened al-
ISO/DIS 15730 Metallic and Other Inorganic Coatings—
loys, using electropolishing procedures.
Electropolishing as a Means of Smoothing and Passivat-
6,7
NOTE 1—Surface passivation occurs simultaneously with electropolish-
ing Stainless Steels
ing under proper operating conditions. The quality of passivation will
ISO/DIS 16348 Metallic and Other Inorganic Coatings—
depend on the type of stainless steel, the formulation of the electropol-
Definitions and Conventions Concerning Appearance
ishing solution, and the conditions of operation. Free iron on the surface
of the stainless steel is removed resulting in improved corrosion resis-
3. Terminology
tance. Surface smoothing obtained by electropolishing will also improve
corrosion resistance. Electropolishing will also remove heat tint and oxide
3.1 Definition of terms in this specification can be found in
scale.
Terminology B 374 and ISO 2080.
3.2 Definitions:
1.2 This specification may involve hazardous materials,
3.2.1 passivation, n—The rendering of a stainless steel
operations, and equipment. This specification does not purport
surface into a lower state of chemical reactivity.
to address all of the safety concerns, if any, associated with its
3.2.1.1 Discussion—Passivated surfaces are characterized
use. It is the responsibility of the user of this standard to
by the absence of free iron, as defined by Practice A 380.
establish appropriate safety and health practices and deter-
3.2.2 electropolishing, n—the electrochemical process in
mine the applicability of regulatory limitations prior to use.
which the article(s) to be passivated are treated anodically in a
2. Referenced Documents
suitable acid medium.
2.1 ASTM Standards:
4. Ordering Information
A 380 Practice for Cleaning and Descaling Stainless Steel
4.1 When ordering articles to be electropolished in con-
Parts, Equipment, and Systems
formance with this standard, the purchaser shall state the
A 967 Specification for Chemical Passivation Treatments
following:
for Stainless Steel Parts
4.1.1 Alloy Designation—When ordering articles passivated
B 117 Practice for Operating Salt Spray (Fog) Apparatus
in accordance with this specification, the purchaser shall state,
B 322 Practice for Cleaning Metals Prior to Electroplating
in addition to the ASTM designation number, the date of issue,
B 374 Terminology Relating to Electroplating
the alloy designation number, and the testing method(s) by
B 602 Test Method for Attribute Sampling of Metallic and
which the article will be evaluated (see 5.3).
Inorganic Coatings
4.1.2 Appearance—The purchaser shall specify the appear-
D 3951 Practice for Commercial Packaging
ance required, for example, bright or dull. Unless otherwise
2.2 ISO Standards:
specified by the purchaser, a bright luster shall be acceptable.
ISO 2080 Electroplating and Related Processes—
Alternatively, samples showing the required finish, or range of
Vocabulary
finish, shall be supplied or approved by the purchaser. When
ISO 4519 Electrodeposited Metallic Coatings and Related
required, the basis material may be subjected, before elec-
tropolishing, to such mechanical polishing as may be required
This specification is under the jurisdiction of ASTM Committee B08 on
to yield the desired final surface characteristics.
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
4.1.3 Contact Marks—Visible contact marks may occur.
B.08.07on Chromate Conversion Coatings.
The location of electrical contact marks shall be agreed upon
Current edition approved Oct. 10, 2000. Published January 2001.
Annual Book of ASTM Standards, Vol 01.03. between purchaser and supplier.
Annual Book of ASTM Standards, Vol 03.02.
Annual Book of ASTM Standards, Vol 02.05.
Annual Book of ASTM Standards, Vol 15.09.
6 7
Available from American National Standards Institute, 11 W. 42nd St., 13th This standard is not a requirement but can be referenced for additional
Floor, New York, NY 10036. information.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
B 912
4.1.4 Metal Removal—Some metal is removed from the one or more of the following test methods (see Section 6 for
surface of the article during electropolishing, typically 5 to 10 test procedures):
μm. As much as 50 μm may be removed for additional 5.3.1.1 Water immersion test,
smoothing. The ordering document shall include the maximum 5.3.1.2 Humidity test,
amount of metal to be removed. 5.3.1.3 Salt spray test,
4.1.5 Any requirement for certification—See Section 9. 5.3.1.4 Copper sulfate test, and
4.1.6 Any requirement for packaging—See Section 10. 5.3.1.5 Modified “ferroxyl” test for free iron.
6. Test Procedures
5. Product Requirements
6.1 Water Immersion Test (Specification A 967)—The ar-
5.1 Visual Defects—When specified, the significant surfaces
ticle(s) shall be alternately immersed in distilled water for 1 h,
of the article to be passivated by electropolishing shall be free
then allowed to dry for 1 h for twelve wet-dry cycles (24 h
of clearly visible defects such as pits, roughness, striations, or
total). Failure is indicated by the presence of red rust or
discoloration when examined with 20/20 eyesight at a distance
staining as a result of the presence of free iron on the surface.
of approximately 0.5 m.
6.2 Humidity Test (Practice A 380, Specification A 967)—
NOTE 2—Defects in the surface of the basis material such as scratches,
The article(s) shall be subjected to 100 % humidity at 38 6
porosity, inclusions, and so forth, may adversely affect the appearance and
2°C in a suitable humidity cabinet for a period of 24 h. Failure
performance of the article. Visible examination shall include wearing
is indicated by the presence of red rust or staining as a result of
correctional glasses if the inspector normally wears them.
the presence of free iron on the surface.
5.2 Process:
6.3 Salt Spray (Fog) Testing (Practice B 117 (ISO 9227))—
5.2.1 Surface Preparation—Preparatory procedures and
The article(s) shall be subjected to the prescribed test for a
cleaning of the basis material may be necessary; see Practices
minimum of2hinan accredited cabinet. Failure is indicated
A 380 and B 322.
by the presence of red rust or staining as a result of the
5.2.2 Electropolishing—Following the preparatory opera-
presence of free iron on the surface.
tions, the articles are introduced into the electropolishing
6.4 Copper Sulfate Test (Practice A 380, Specification
solution for a period of time at the current density and
A 967)—See Appendix X2. The article is swabbed with an
temperature required to produce the passive surface and
acidified solution of copper sulfate. Failure is indicated by the
required surface finish, if any.
presence of a copper-colored deposit or copper-colored spots,
or both. This test is not to be used on martensitic 400 series
NOTE 3—A typical electropolishing solution and operating conditions
suitable for many st
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