ASTM F1941-00
(Specification)Standard Specification for Electrodeposited Coatings on Threaded Fasteners (Unified Inch Screw Threads (UN/UNR))
Standard Specification for Electrodeposited Coatings on Threaded Fasteners (Unified Inch Screw Threads (UN/UNR))
SCOPE
1.1 This specification covers application, performance and dimensional requirements for electrodeposited coatings on threaded fasteners with unified inch screw threads. It specifies coating thickness, supplementary chromate 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 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.
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Designation: F 1941 – 00
Standard Specification for
Electrodeposited Coatings on Threaded Fasteners (Unified
1
Inch Screw Threads (UN/UNR))
This standard is issued under the fixed designation F 1941; 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 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 2. Referenced Documents
1.1 This specification covers application, performance and 2.1 ASTM Standards:
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dimensional requirements for electrodeposited coatings on B 117 Practice for Operating Salt Spray (Fog) Apparatus
threaded fasteners with unified inch screw threads. It specifies B 487 Test Method for Measurement of Metal and Oxide
coating thickness, supplementary chromate finishes, corrosion Coating Thickness by Microscopical Examination of a
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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-
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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-
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1.2 The values stated in SI units are to be regarded as the tallic Coatings by the Coulometric Method
standard. The values given in parentheses are for information B 567 Test Method for Measurement of Coating Thickness
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only. by the Beta Backscatter Method
1.3 The following precautionary statement pertains to the B 568 Test Method for Measurement of Coating Thickness
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test method portion only, Section 9, of this specification: This by X-Ray Spectrometry
standard does not purport to address all of the safety concerns, B 633 Specification for Electrodeposited Coatings of Zinc
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if any, associated with its use. It is the responsibility of the user on Iron and Steel
of this standard to establish appropriate safety and health B 659 Guide for Measuring Thickness of Metallic and
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practices and determine the applicability of regulatory limita- Inorganic Coatings
tions prior to use. B 766 Specification for Electrodeposited Coatings of Cad-
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mium
B 840 Specification for Electrodeposited Coatings of Zinc
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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.
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Current edition approved Jan. 10, 2000. Published March 2000. Originally Annual Book of ASTM Standards, Vol 03.02.
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published as F 1941–98. Last previous edition F 1941–98. Annual Book of ASTM Standards, Vol 02.05.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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F1941–00
NOTE 1—Black dot (•) indicates test surface.
FIG. 1 Significant Surfaces on Externally Threaded Fasteners
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Cobalt Alloy Deposits which are essential to the appearance or serviceability of the
B 841 Specification for Electrodeposited Coatings of Zinc fastener when assembled in normal position, or which can be
3
Nickel Alloy Deposits the source of corrosion products that deface visible surfaces on
B 842 Specification for Electrodeposited Coatings of Zinc the assembled fastener. Figs. 1 and 2 illustrate significant
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Iron Alloy Deposits surfaces on standard externally threaded and internally
E 376 Practice for Measuring Coating Thickness by threaded fasteners.
Magnetic-Field or Eddy-Current (Electromagnet
...
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