ASTM F1941-10

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Designation:F1941–07 Designation: F1941 – 10
Standard Specification for
Electrodeposited Coatings on Threaded Fasteners (Unified
1
Inch Screw Threads (UN/UNR))
This standard is issued under the fixed designation F1941; 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.
INTRODUCTION
This specification covers the coating of steel unified inch screw threaded fasteners by electrodepo-
sition. The properties of the coatings shall conform to theASTM standards for the individual finishes
listed.
Coating thickness values are based on the tolerances for 1A and 2A external Unified Inch Screw
Threads. The coating must not cause the basic thread size to be transgressed by either the internal or
external threads. The method of designating coated threads shall comply with ASME B1.1.
With normal methods for depositing metallic coatings from aqueous solutions, there is a risk of
delayed failure due to hydrogen embrittlement for case hardened fasteners and fasteners having a
hardness 40 HRC or above.Although this risk can be managed by selecting raw materials suitable for
the application of electrodeposited coatings and by using modern methods of surface treatment and
post heat-treatment (baking), the risk of hydrogen embrittlement cannot be completely eliminated.
Therefore, the application of a metallic coating by electrodeposition is not recommended for such
fasteners.
1. Scope*
1.1This1.1 This specification covers application, performance and dimensional requirements for electrodeposited coatings on
threaded fasteners with unified inch screw threads. It specifies coating thickness, supplementary hexavalent chromate or trivalent
chromitenon-hexavalent passivate finishes, corrosion resistance, precautions for managing the risk of hydrogen embrittlement and
hydrogen embrittlement relief for high-strength and surface-hardened fasteners. It also highlights the differences between barrel
and rack plating and makes recommendations as to the applicability of each process.
1.2 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3 The following precautionary statement pertains to the test method portion only, Section 9, 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.
2. Referenced Documents
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2.1 ASTM Standards:
B117 Practice for Operating Salt Spray (Fog) Apparatus
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
B567 Test Method for Measurement of Coating Thickness by the Beta Backscatter Method
B568 Test Method for Measurement of Coating Thickness by X-Ray Spectrometry
B659 Guide for Measuring Thickness of Metallic and Inorganic Coatings
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This specification is under the jurisdiction of ASTM Committee F16 on Fasteners and is the direct responsibility of Subcommittee F16.03 on Coatings on Fasteners.
Current edition approved Dec. 1, 2007.15, 2010. Published January 2008.2011. Originally approved in 1998. Last previous edition approved in 20062007 as F1941–00
(2006). F1941 – 07. DOI: 10.1520/F1941-107.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. 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.
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F1941 – 10
NOTE 1—Black dot (•) indicates test surface.
FIG. 1 Significant Surfaces on Externally Threaded Fasteners
D6492 Practice for Detection of Hexavalent Chromium On Zinc and Zinc/Aluminum Alloy Coated Steel
E376 Practice for Measuring Coating Thickness by Magnetic-Field
...