ASTM F1941M-05

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Designation: F 1941M – 05
METRIC
Standard Specification for
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Electrodeposited Coatings on Threaded Fasteners [Metric]
This standard is issued under the fixed designation F 1941M; 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.
INTRODUCTION
This specification covers the coating of steel metric screw threaded fasteners by electrodeposition.
The properties of the coatings shall conform to theASTM standards for the individual finishes listed.
Coating thickness values are based on the tolerances for M series metric threads having the
following tolerance positions: 6g and 4g6g for external threads, and 6H for internal 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 B1.13M.
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 2. Referenced Documents
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1.1 This specification covers application, performance and 2.1 ASTM Standards:
dimensional requirements for electrodeposited coatings on B117 Practice for Operating Salt Spray (Fog) Apparatus
threaded fasteners with metric screw threads. It specifies B 487 Test Method for Measurement of Metal and Oxide
coating thickness, supplementary chromate finishes, corrosion Coating Thickness by Miocroscopical Examination of a
resistance, precautions for managing the risk of hydrogen Cross Section
embrittlement and hydrogen embrittlement relief for high- B 499 Test Method for Measurement of Coating Thickness
strength and surface-hardened fasteners. It also highlights the by the Magnetic Method: Nonmagnetic Coatings on Mag-
differences between barrel and rack plating and makes recom- netic Basis Metals
mendations as to the applicability of each process. B 504 Test Method for Measurement of Thickness of Me-
1.2 The following precautionary statement pertains to the tallic Coatings by the Coulometric Method
test method portion only, Section 9, of this specification: This B 567 Test Method for Measurement of Coating Thickness
standard does not purport to address all of the safety concerns, by the Beta Backscatter Method
if any, associated with its use. It is the responsibility of the user B 568 Test Method for Measurement of Coating Thickness
of this standard to establish appropriate safety and health by X-Ray Spectrometry
practices and determine the applicability of regulatory limita- B 659 Guide for Measuring Thickness of Metallic and
tions prior to use. Inorganic Coatings
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This specification is under the jurisdiction of ASTM Committee F16 on
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Fasteners and is the direct responsibility of Subcommittee F16.03 on Coatings on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Fasteners. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved May 1, 2005. Published May 2005. Originally Standards volume information, refer to the standard’s Document Summary page on
approved in 2000. Last previous edition approved in 2000 as F 1941M – 00.
the ASTM website.
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F 1941M – 05
NOTE 1—Black dot (•) indicates test surface.
FIG. 1 Significant surfaces on Externally Threaded Fasteners
E 376 Practice for Measuring Coating Thickness by
Magnetic-FieldorEddy-Current(Electromagnetic)Exami-
nation Methods
F 606 Test Methods for Determining the Mechanical Prop-
erties of Externally and Internally Threaded Fasteners,
Washers, and Rivets NOTE 1—Black dot (•) indicates test surface.
FIG. 2 Significant surfaces on Internally Threaded Fasteners
F 1470 GuideforFastenerSamplingforSpecifiedMechani-
cal Properties and Performance Inspection
TABLE 1 Designation of Common Coating Materials
F 1624 Test Method for Measurement of Hydrogen Em-
brittlement Threshold in Steel by the Incremental Step Coating Designation Coating Type
Loading Technique
Fe/Zn Zinc
Fe/Cd Cadmium
F 1940 Test Method for Process Cont
...