1、Designation: F1941/F1941M 16Standard Specification forElectrodeposited Coatings on Mechanical Fasteners, Inchand Metric1This standard is issued under the fixed designation F1941/F1941M; the number immediately following the designation indicates the yearof original adoption or, in the case of revisio
2、n, 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.INTRODUCTIONThis specification covers the coating of steel unified inch and metric mechanical fasteners byelectrode
3、position. The properties of the coatings shall conform to the ASTM standards for theindividual finishes. This standard shall be used in place of ASTM B633 for mechanical fasteners.Coating thickness values are based on standard tolerances for inch and metric external threads. Thecoating must not caus
4、e the basic thread size to be transgressed by either the internal or externalthreads. The method of designating inch coated threads shall comply withASME B1.1 and ISO 965-1,ISO 965-2, and ISO 965-3 for ISO metric coated threads.With normal methods for depositing metallic coatings from aqueous soluti
5、ons, there is a risk ofdelayed failure due to hydrogen embrittlement for case hardened fasteners and fasteners having ahardness above 39 HRC.Although this risk can be managed by selecting raw materials suitable for theapplication of electrodeposited coatings and by using modern methods of surface tr
6、eatment and postheat-treatment (baking), the risk of hydrogen embrittlement cannot be completely eliminated.Therefore, the application of a metallic coating by electrodeposition is not recommended for suchfasteners.1. Scope*1.1 This specification covers application, performance anddimensional requir
7、ements for electrodeposited coatings onthreaded fasteners with unified inch and metric screw threads,but it may also be applied to other threaded parts andnon-threaded parts such as washers and pins. It specifiescoating thickness, supplementary hexavalent chromate or non-hexavalent conversion coatin
8、gs, corrosion resistance, precau-tions for managing the risk of hydrogen embrittlement andhydrogen embrittlement relief for high-strength and surface-hardened fasteners. It also highlights the differences betweenbarrel and rack plating and makes recommendations as to theapplicability of each process
9、.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith
10、 the standard.1.3 Terms used in this specification are defined in Termi-nology F1789.1.4 The following precautionary statement pertains to thetest method portion only, Section 9, of this specification: Thisstandard does not purport to address all of the safety concerns,if any, associated with its us
11、e. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2. Referenced Documents2.1 ASTM Standards:2B117 Practice for Operating Salt Spray (Fog) ApparatusB487 Test Method for Me
12、asurement of Metal and OxideCoating Thickness by Microscopical Examination ofCross SectionB499 Test Method for Measurement of Coating Thicknessesby the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis MetalsB504 Test Method for Measurement of Thickness of Metal-lic Coatings by the Coulometric
13、Method1This specification is under the jurisdiction of ASTM Committee F16 onFasteners and is the direct responsibility of Subcommittee F16.03 on Coatings onFasteners.Current edition approved Dec. 1, 2016. Published January 2017. Originallyapproved in 1998. Last previous edition approved in 2015 as F
14、1941/F1941M 15.DOI: 10.1520/F1941_F1941M-162For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Chan
15、ges section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Dec
16、ision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1B567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter MethodB568 Test Method for Measurement of Coa
17、ting Thicknessby X-Ray SpectrometryB633 Specification for Electrodeposited Coatings of Zinc onIron and SteelB659 Guide for Measuring Thickness of Metallic and Inor-ganic CoatingsD6492 Practice for Detection of Hexavalent Chromium OnZinc and Zinc/Aluminum Alloy Coated SteelE376 Practice for Measuring
18、 Coating Thickness byMagnetic-Field or Eddy-Current (Electromagnetic) Test-ing MethodsF519 Test Method for Mechanical Hydrogen EmbrittlementEvaluation of Plating/Coating Processes and Service En-vironmentsF606/F606M Test Methods for Determining the MechanicalProperties of Externally and Internally T
19、hreadedFasteners, Washers, Direct Tension Indicators, and RivetsF788 Specification for Surface Discontinuities of Bolts,Screws, and Studs, Inch and Metric SeriesF1470 Practice for Fastener Sampling for Specified Me-chanical Properties and Performance InspectionF1624 Test Method for Measurement of Hy
20、drogen Em-brittlement Threshold in Steel by the Incremental StepLoading TechniqueF1789 Terminology for F16 Mechanical FastenersF1940 Test Method for Process Control Verification toPrevent Hydrogen Embrittlement in Plated or CoatedFastenersF2078 Terminology Relating to Hydrogen EmbrittlementTesting2.
21、2 ASME Standards:3B1.1 Unified Inch Screw Threads (UN and UNR ThreadForm)B1.2 Gages and Gaging for Unified Inch Screw ThreadsB1.16M Gages and Gaging for Metric M Screw ThreadsB18.6.3 Machine Screws, Tapping Screws, and MetallicDrive Screws (Inch Series)2.3 National Aerospace Standard (AIA):4NASM-131
22、2-5 Fast Test Method Method 5: Stress Dura-bility2.4 IFI Standard:5IFI-142 Hydrogen Embrittlement Risk Management2.5 ISO Standards:6ISO 965-1 ISO General Purpose Metric Screw Threads Tolerances Part 1: Principles and Basic DataISO 965-2 ISO General Purpose Metric Screw Threads Tolerances Part 2: Lim
23、its of Sizes for General PurposeExternal and Internal Screw ThreadsISO 965-3 ISO General Purpose Metric Screw Threads Tolerances Part 3: Deviations for Construction ScrewThreadsISO 4042 Electroplated Coatings3. Terminology3.1 Definitions:3.1.1 reference areathe area within which a specifiednumber of
24、 single measurements are required to be made.3.1.2 sealantchemical with or without integral lubricantapplied on the substrate which forms a composite layer with aconversion coating in order to improve chemical resistance,corrosion protection, UV resistance, etc.3.1.3 significant surfaceFigs. 1 and 2
25、 illustrate significantsurfaces on standard externally and internally threaded fasten-ers and washers.3.1.4 top coatadditional layer with or without integrallubricant applied on a substrate in order to achieve functionalproperties such as torque-tension control, color, chemicalresistance, etc.4. Cla
26、ssification4.1 Coating MaterialThe coating material shall be se-lected and designated in accordance with Table 1.4.2 Coating ThicknessThe coating thickness shall be se-lected and designated in accordance with Table 2.4.3 Conversion CoatingThe conversion coating shall beselected and designated in acc
27、ordance with Table 3. When notspecified, hexavalent chromium, or hexavalent chromium freepassivation such as trivalent chromium passivation or other3Available from American Society of Mechanical Engineers (ASME), ASMEInternational Headquarters, Three Park Ave., New York, NY 10016-5990, http:/www.asm
28、e.org.4Available from DLA Document Services, Building 4/D, 700 Robbins Ave.,Philadelphia, PA 19111-5094, http:/quicksearch.dla.mil.5Available from Industrial Fasteners Institute (IFI), 1717 East 9th Street, Suite1105, Cleveland, OH 441142879.6Available from American National Standards Institute (ANS
29、I), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.NOTE 1Black dot () indicates test surface.FIG. 1 Significant Surfaces on Externally Threaded FastenersNOTE 1Black dot () indicates test surface.FIG. 2 Significant Surfaces on Internally Threaded Fasteners andWashersF1941/F1941M 162
30、non-chromium passivation finish shall be used at the option ofthe manufacturer and its appearance shall be selected inaccordance with the designation selected in Table 3.4.4 Supplemental Lubricant, Sealants or Top CoatsAdditional sealants or top coats (with or without integrallubricant) may be chose
31、n to increase corrosion resistance andto achieve other specific properties such as torque-tension, UVresistance, etc. The selection of the nature of a sealant or topcoat should be based on desired additional properties. Whensealants or top coats are specified, the classification code inTable 3 shall
32、 be appended by adding the letter “S” (for exampleFe/Zn 5ANS). When specifying a lubricant, the classificationcode in Table 3shall be appended with the letter “L” (forexample Fe/Zn 5ANSL).NOTE 1When using a sealant or top coat, a separate conversioncoating layer and/or lubricant layer may not be req
33、uired to achieve thecorrosion performance or provide lubricity.4.5 Fig. 3 illustrates the basic electroplating coating sys-tems.4.5.1 Only coating material layer(s).4.5.2 Coating material layer(s) plus conversion coating (forexample Fe/Zn 5A).4.5.3 Coating material layer(s) plus conversion coating p
34、lusadditional lubricant (example Fe/Zn 5ANL).4.5.4 Coating material layer(s) plus conversion coating plussealant top coat (example Fe/Zn 5ANS).4.5.5 Coating material layer(s) plus conversion coating plussealant top coat plus additional lubricant (example Fe/Zn5ANSL).5. Ordering Information for Elect
35、roplating5.1 When ordering threaded fasteners to be coated byelectrodeposition in accordance with this specification, thefollowing information shall be supplied to the electroplater:5.1.1 The desired coating, coating thickness, the conversioncoating, the color and appearance (if applicable), or thec
36、lassification codes as specified in Tables 1-3 and additionalsealants or top coats (for example, Fe/Zn 5C denotes yellowzinc plated with a minimum thickness of 0.0002 in. or 5 m formetric on significant surfaces).5.1.2 The identification of significant surfaces (optional).5.1.3 The requirement, if a
37、ny, for stress relief beforeelectroplating, in which case the stress-relief conditions mustbe specified.5.1.4 The requirements, if any, for hydrogen embrittlementrelief by heat treatment (baking), other than as required by6.4.1 must be specified. Requirements shall include bakingtime and temperature
38、.5.1.5 The requirements, if any, for embrittlement testingother than as required by 6.4.3 must be specified.NOTE 2Through hardened fasteners with a specified maximumhardness of 39 HRC and below have a low susceptibility to hydrogenembrittlement and do not require baking.5.1.6 The requirements, if an
39、y, for the type of electroplatingprocess (barrel-plating or rack-plating). See Section 10 andAppendix X1.5.1.7 The designation of inch coated thread class shallcomply withASME B1.1 and metric threads shall comply withISO 965-1, ISO 965-2 and ISO 965-3.6. Requirements6.1 Coating RequirementsThe elect
40、rodeposited coating asordered shall cover all surfaces and shall meet the followingrequirements:6.1.1 The coating metal deposit shall be bright or semi-bright unless otherwise specified by the purchaser, smooth, finegrained, adherent and uniform in appearance.6.1.2 The coated fastener shall be free
41、of blisters, pits,nodules, roughness, unplated areas, and other defects that willaffect the function of the coating.TABLE 1 Designation of Common Coating MaterialsCoating Designation Coating TypeFe/Zn ZincFe/Cd CadmiumFe/Zn-Co Zinc Cobalt AlloyFe/Zn-Ni Zinc Nickel AlloyFe/Zn-Fe Zinc Iron AlloyTABLE
42、2 Designation of Coating Thickness Inch and MetricNOTE 1The conversion factor from inch to microns is 2.54 104(forexample, 0.0001 in. = 2.54 m).ThicknessDesignationMinimum Thicknessin. m3 0.0001 35 0.0002 58 0.0003 812 0.0005 12TABLE 3 Designation of Conversion CoatingType Typical AppearanceConversi
43、on DesignationHexavalentChromiumHexavalentChromiumFreeClear Transparent colorless with slightiridescenceAANBlue-bright Transparent with a bluish tingeand slight iridescenceBBNYellow Yellow iridescent C CNOpaque Olive green, shading to brown orbronzeDDBlack Black with slight iridescence E ENFIG. 3 Ba
44、sic Electroplating Coating SystemsF1941/F1941M 1636.1.3 The coating shall not be stained, discolored or exhibitany evidence of corrosion products.6.1.3.1 Slight discoloration that results from baking, drying,or electrode contact during rack-plating, or all of these, as wellas slight staining that re
45、sults from rinsing shall not be cause forrejection.6.2 Corrosion ResistanceCoated fasteners, when tested bycontinuous exposure to neutral salt spray in accordance with9.3, shall show neither corrosion products of coatings nor basismetal corrosion products at the end of the test period. Theappearance
46、 of corrosion products visible to the unaided eye atnormal reading distance shall be cause for rejection, exceptwhen present at the edges of the tested fasteners. Refer toAnnex A1 for neutral salt spray performance requirements forzinc, zinc alloy and cadmium coatings.6.3 ThicknessThe coating thickn
47、ess shall comply withrequirements of Table 2 when measured in accordance with9.1.6.3.1 Restrictions on Coating ThicknessThis specificationimposes minimum local thickness requirements at significantsurfaces in accordance with Table 2. Thick or thin localthickness in a location other than a significan
48、t surface shall notbe a cause for rejection. However the following restrictionsapply:6.3.1.1 Minimum coating thickness at low current densityareas, such as the center of a bolt or recesses, must be sufficientto provide for adequate conversion coating adhesion.6.3.1.2 External ThreadsThe after-coatin
49、g dimensions ofexternal threads must not exceed the threads basic size. Coatedexternal threads must conform to a basic GO gage. Coated inchexternal threads must accept a class 3A GO gage and coatedmetric threads must accept a class h (6h or 4h) GO gage (SeeASME B1.2 and ASME B1.16M respectively). The NOTGOgage size is the same after coating as before coating. If a coatedexternal thread does not freely enter the basic size GO gage,the thread discontinuity torque test in Specification F788 shallbe used to determine thread acceptability.6.3.
