ASTM B840-22

Standard Specification for Electrodeposited Coatings of Zinc Cobalt Alloy Deposits

ABSTRACT
This specification covers the requirements for electrodeposited zinc cobalt alloy coatings on metals. The coating class is Class 1 and five coating types are Type a, Type b, Type c, Type d, and Type e. The metal to be plated shall be subjected to such cleaning, pickling, and electroplating procedures. Coating requirements include: substrate, nature of coating, appearance, thickness, adhesion, corrosion resistance, and pre- and post-coating treatments of iron and steel for reducing the risk of hydrogen embrittlement. Adhesion, porosity, corrosion resistance, or appearance tests shall be made.
SCOPE
1.1 This specification covers the requirements for electrodeposited zinc cobalt alloy coatings on metals.  
1.2 The following precautionary caveat pertains to the test method portion only, Section 8, 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.3 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.

General Information

• Status: Published
• Publication Date: 14-Nov-2022
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.06 - Soft Metals

Standards Content (Sample)

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.
Designation:B840 −22
Standard Specification for
1
Electrodeposited Coatings of Zinc Cobalt Alloy Deposits
This standard is issued under the fixed designation B840; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* B504Test Method for Measurement of Thickness of Metal-
lic Coatings by the Coulometric Method
1.1 Thisspecificationcoverstherequirementsforelectrode-
B507Practice for Design ofArticles to Be Electroplated on
posited zinc cobalt alloy coatings on metals.
Racks
1.2 The following precautionary caveat pertains to the test
B568Test Method for Measurement of Coating Thickness
method portion only, Section 8, of this specification: This
by X-Ray Spectrometry
standard does not purport to address all of the safety concerns,
B571Practice for Qualitative Adhesion Testing of Metallic
if any, associated with its use. It is the responsibility of the user
Coatings
of this standard to establish appropriate safety, health, and
B602Guide for Attribute Sampling of Metallic and Inor-
environmental practices and determine the applicability of
ganic Coatings
regulatory limitations prior to use.
B697Guide for Selection of Sampling Plans for Inspection
1.3 This international standard was developed in accor-
of Electrodeposited Metallic and Inorganic Coatings
dance with internationally recognized principles on standard-
B762GuideofVariablesSamplingofMetallicandInorganic
ization established in the Decision on Principles for the
Coatings
Development of International Standards, Guides and Recom-
B849Specification for Pre-Treatments of Iron or Steel for
mendations issued by the World Trade Organization Technical
Reducing Risk of Hydrogen Embrittlement
Barriers to Trade (TBT) Committee.
B850GuideforPost-CoatingTreatmentsofSteelforReduc-
ing the Risk of Hydrogen Embrittlement
2. Referenced Documents
D3951Practice for Commercial Packaging
2
2.1 ASTM Standards:
B117Practice for Operating Salt Spray (Fog) Apparatus
3. Terminology
B183Practice for Preparation of Low-Carbon Steel for
3.1 Definitions—Many terms used in this specification are
Electroplating
defined in Terminology B374.
B242Guide for Preparation of High-Carbon Steel for Elec-
troplating 3.2 Definitions of Terms Specific to This Standard:
3.2.1 significant surface, n—that portion of a coated arti-
B320Practice for Preparation of Iron Castings for Electro-
cle’s surface where the coating is required to meet all the
plating
requirements of the coating specification for that article.
B322Guide for Cleaning Metals Prior to Electroplating
Significant surfaces are usually those that are essential to the
B374Terminology Relating to Electroplating
serviceability or function of the article or can be a source of
B487Test Method for Measurement of Metal and Oxide
corrosion products or tarnish films that interfere with the
Coating Thickness by Microscopical Examination of
function or desirable appearance of the article. Significant
Cross Section
surfaces are those surfaces that are identified by the purchaser
B499Test Method for Measurement of CoatingThicknesses
by, for example, indicating them on an engineering drawing of
by the Magnetic Method: Nonmagnetic Coatings on
the product or marking a sample item of the product.
Magnetic Basis Metals
4. Classification
1
This specification is under the jurisdiction of ASTM Committee B08 on
4.1 There is one coating class, and it is defined as Class
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
B08.06 on Soft Metals.
1—azinccobaltalloythatisapproximately99%bymasszinc
Current edition approved Nov. 15, 2022. Published December 2022. Originally
and at minimum 0.5% by mass cobalt.
approved in 1993. Last previous edition approved in 2015 as B840–15. DOI:
10.1520/B0840-22.
4.2 There are five coating types and they are defined as
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
follows:
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
4.2.1 Type A—With colorless (blue bright) chromate con-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. version coatings.
*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
1

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B840−22
ASTMpracticesforcleaning,whereappropriate,beused:PracticesB183,
4.2.2
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B840 − 15 B840 − 22
Standard Specification for
1
Electrodeposited Coatings of Zinc Cobalt Alloy Deposits
This standard is issued under the fixed designation B840; 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 Scope*
1.1 This specification covers the requirements for electrodeposited zinc cobalt alloy coatings on metals.
1.2 The following precautionary caveat pertains to the test method portion only, Section 8, 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 safety, health, and healthenvironmental practices and determine the applicability of
regulatory limitations prior to use.
1.3 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.
2. Referenced Documents
2
2.1 ASTM Standards:
B117 Practice for Operating Salt Spray (Fog) Apparatus
B183 Practice for Preparation of Low-Carbon Steel for Electroplating
B242 Guide for Preparation of High-Carbon Steel for Electroplating
B320 Practice for Preparation of Iron Castings for Electroplating
B322 Guide for Cleaning Metals Prior to Electroplating
B374 Terminology Relating to Electroplating
B487 Test Method for Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of Cross Section
B499 Test Method for Measurement of Coating Thicknesses by the Magnetic Method: Nonmagnetic Coatings on Magnetic Basis
Metals
B504 Test Method for Measurement of Thickness of Metallic Coatings by the Coulometric Method
B507 Practice for Design of Articles to Be Electroplated on Racks
B568 Test Method for Measurement of Coating Thickness by X-Ray Spectrometry
B571 Practice for Qualitative Adhesion Testing of Metallic Coatings
B602 Guide for Attribute Sampling of Metallic and Inorganic Coatings
B697 Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings
B762 Guide of Variables Sampling of Metallic and Inorganic Coatings
B849 Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement
B850 Guide for Post-Coating Treatments of Steel for Reducing the Risk of Hydrogen Embrittlement
D3951 Practice for Commercial Packaging
1
This specification is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.06 on Soft
Metals.
Current edition approved May 1, 2015Nov. 15, 2022. Published June 2015December 2022. Originally approved in 1993. Last previous edition approved in 20092015 as
B840 – 99B840 – 15.(2009). DOI: 10.1520/B0840-15.10.1520/B0840-22.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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
1

---------------------- Page: 1 ----------------------
B840 − 22
3. Terminology
3.1 Definitions—Many terms used in this specification are defined in Terminology B374.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 significant surface, n—that portion of a coated article’s surface where the coating is required to meet all the requirements
of the coating specification for that article. Significant surfaces are usually those that are essential to the serviceability or function
of the article or can be a source of corrosion products or tarnish films that interfere with the function or desirable appearance of
the article. Significant surfaces are those surfaces that are identified by the purchaser by, for example, indicating them on an
engineering drawing of the product or marking a sample item of the product.
4. Classification
4.1 There is one coating class, and it is defined as Class 1—a zinc cobalt alloy that is approximately 99%99 % by mas
...