1、Designation: A 153/A 153M 05American Association State Highwayand Transportation Officials StandardAASHTO No. M232Standard Specification forZinc Coating (Hot-Dip) on Iron and Steel Hardware1This standard is issued under the fixed designationA 153/A 153M; the number immediately following the designat
2、ion indicates the yearof 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.This standard has been approved for use by ag
3、encies of the Department of Defense.1. Scope*1.1 This specification covers zinc coatings applied by thehot-dip process on iron and steel hardware. The hot-dipgalvanizing process consists of parts being immersed in moltenzinc for a sufficient time to allow a metallurgical reactionbetween iron from th
4、e steel surface and the molten zinc,resulting in the formation of Zn/Fe alloy layers bonding thecoating to the steel surface.1.2 This specification is intended to be applicable to hard-ware items that are centrifuged or otherwise handled to removeexcess galvanizing bath metal (free zinc). Coating th
5、icknessgrade requirements reflect this.1.3 This specification is applicable to orders in eitherinch-pound units (as A 153) or in SI units (as A 153M).Inch-pound units and SI units are not necessarily exactequivalents. Within the text of this specification and whereappropriate, SI units are shown in
6、brackets. Each system shallbe used independently of the other without combining values inany way. In the case of orders in SI units, all testing andinspection shall be done using the metric equivalent of the testor inspection method as appropriate. In the case of orders in SIunits, such shall be sta
7、ted to the galvanizer when the order isplaced.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regul
8、atory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A 90/A 90M Test Method for Weight of Coating on Zinc-Coated (Galvanized) Iron or Steel ArticlesA 143 Practice for Safeguarding Against Embrittlement ofHot-Dip Galvanized Structural Steel Products and Proce-dure for Detecting E
9、mbrittlementA 780 Practice for Repair of Damaged and Uncoated Areasof Hot-Dip Galvanized CoatingsA 902 Terminology Relating to Metallic Coated Steel Prod-uctsB6 Specification for Zinc (Slab Zinc)B 487 Test Method for Measurement of Metal and OxideCoating Thicknesses by Microscopical Examination of a
10、Cross SectionE 376 Practice for Measuring Coating Thickness byMagnetic-Field or Eddy-Current (Electromagnetic) TestMethodsF 1470 Guide for Fastener Sampling for Specified Mechani-cal Properties and Performance InspectionF 1789 Terminology for F16 Mechanical Fasteners3. Terminology3.1 Definitions:3.1
11、.1 The following terms and definitions are specific to thisspecification. Terminology A 902 contains other terms anddefinitions relating to metallic-coated steel products. Terminol-ogy F 1789 contains other terms and definitions relating tomechanical fasteners.1This specification is under the jurisd
12、iction of ASTM Committee A05 onMetallic-Coated Iron and Steel Products and is the direct responsibility ofSubcommittee A05.13 on Structural Shapes and Hardware Specifications.Current edition approved April 1, 2005. Published May 2005. Originallyapproved in 1933. Last previous edition approved in 200
13、4 as A 153/A 153M - 04.2For 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.1*A Summary of Changes section appears
14、 at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 Definitions of Terms Specific to This Standard:3.2.1 average coating thickness, nthe average of thespecimen coating thickness values for the samples in a
15、ninspection lot.3.2.2 bare spots, nuncoated areas on the surface of thesteel part that contain no measurable zinc coating.3.2.3 dross inclusions, nthe iron/zinc intermetallicspresent in a galvanized coating in a form other than the layergrowth of the coating.3.2.4 individual measurement, nthe readin
16、g from a mag-netic thickness gauge of a single coating spot thickness, or themicroscopic reading of a coating thickness as seen in an opticalmicroscope at one spot.3.2.5 inspection lot, nthe quantity of identical partscleaned, fluxed and galvanized together at one time in anappropriate container tha
17、t is being submitted for acceptance asa group.3.2.6 malleable casting, na steel article that has beensubjected to a prolonged anneal to decarburize or graphitize thepart to remove as much of the carbon as possible or to convertthe carbon to graphite, which permits plastic deformation incompression w
18、ithout rupture.3.2.7 sample, na collection of individual units of productfrom a single inspection lot selected in accordance with Section6 and intended to represent that inspection lot for acceptance.3.2.8 specimen, nan individual test article upon whichthickness measurements or weight determination
19、s are per-formed.3.2.9 specimen coating thickness, nthe average thicknessfrom no less than five test measurements on a specimen, wheneach measurement location is selected to provide the widestdispersion (in all applicable directions) of locations within thespecimen volume.3.2.10 threaded areas, nthe
20、 sections of a steel part thathave threads formed before hot-dip galvanizing.4. Materials and Manufacture4.1 Steel or IronFerrous articles to be hot-dip zinc coatedshall conform to specifications designated by the purchaser.4.2 ZincThe zinc used for the coating shall conform toSpecification B6 and s
21、hall be at least equal to the gradedesignated as “Prime Western.”4.2.1 If a zinc alloy is used as the primary feed for thegalvanizing bath, then the base material used to make that alloyshall conform to Specification B6.4.2.2 The molten metal in the working volume of thegalvanizing bath shall contai
22、n not less than an average value of98.0 % zinc by weight mass.NOTE 1The galvanizer may choose to add trace amounts of certainelements (for example, aluminum, nickel, bismuth, or tin) to the zinc bathto help in the processing of certain reactive steels or to enhance thecosmetic appearance of the fini
23、shed product. The elements can be addedto the galvanizing bath as a master feed alloy, or they can be added to thebath by the galvanizer as individual feeds.4.3 Minimum Coating Weight Mass or Minimum CoatingThicknessThe minimum coating weight mass or the mini-mum coating thickness shall conform to t
24、he requirementsprescribed in Table 1 for the material category and thickness ofmaterial in which the article belongs.4.4 Threaded ArticlesThe zinc coating on threads shallnot be subjected to a cutting, rolling, or finishing-tool opera-tion, unless specifically authorized by the purchaser. In order t
25、omeet overtapping allowances, tapping the threads of nuts ortapped holes after galvanizing is not prohibited.4.5 Touch-up and RepairBare spots that are found onparts after galvanizing shall be renovated by use of the methodsfound in Practice A 780 if the following criteria are met. Thebare spots sha
26、ll have an area totalling not more than 1 % of thesurface area to be coated excluding threaded areas of the pieceand the bare spots shall not include any threaded areas of thepiece. The thickness of the repair shall be equal to thesurrounding galvanized coating except for repairs made bypaints conta
27、ining zinc dust in which case the thickness of therepair shall be 50 % greater than the thickness of the galva-nized coating required for the class of material, but shall not begreater than 4.0 mils 100 m. Repair thickness measurementsTABLE 1 Thickness or Weight Mass of Zinc Coating for Various Clas
28、ses of MaterialNOTE 1 Length of the piece, stated in Classes B-1, B-2, and B-3, refers to the finished dimension of the piece after fabrication.Class of MaterialWeight Mass of Zinc Coating,oz/ft2g/m2 of Surface, MinimumCoating Thickness, milsmicrons, MinimumAverage ofSpecimensTestedAnyIndividualSpec
29、imenAverage ofSpecimensTestedAnyIndividualSpecimenClass ACastingsMalleable Iron, Steel 2.00 610 1.80 550 3.4 86 3.1 79Class BRolled, pressed, and forged articles(except those which would be included under Classes C and D):B-1316 in. 4.76 mm and over in thicknessand over 15 in. 381 mm in length2.00 6
30、10 1.80 550 3.4 86 3.1 79B-2under316 in. 4.76 mm in thickness andover 15 in. 381 mm in length1.50 458 1.25 381 2.6 66 2.1 53B-3any thickness and 15 in. 381 mm and under in length 1.30 397 1.10 336 2.2 56 1.9 48Class CFasteners over38 in. 9.52 mm in diameterand similar articles. Washers316 in. and14
31、in. 4.76 and 6.35mm in thickness1.25 381 1.00 305 2.1 53 1.7 43Class DFasteners38 in. 9.52 mm and under in diameter,rivets, nails and similar articles. Washers under316 in. 4.76mm in thickness1.00 305 0.85 259 1.7 43 1.4 36A 153/A 153M 052shall be made in accordance with Practice A 780. The galva-ni
32、zer shall make repairs unless directed by the purchaser todeliver items unrepaired for subsequent renovation by thepurchaser.5. Workmanship, Finish, and Appearance5.1 The zinc-coated articles shall be free from uncoatedareas, blisters, flux deposits, dross inclusions, and other typesof projections t
33、hat would interfere with the intended use of thearticles, or other defects not consistent with good galvanizingpractice.5.2 The zinc coating shall be smooth and reasonably uni-form in thickness.NOTE 2Smoothness of surface is a relative term. Minor roughnessthat does not interfere with the intended u
34、se of the part, or roughness thatis related to the as-received (ungalvanized) surface condition of the part,shall not be grounds for rejection.NOTE 3Since this specification is applicable to items that are centri-fuged or otherwise handled to remove excess bath metal (see 1.2),irregular coating dist
35、ribution is not normally encountered. Drainageproblems, which manifest themselves as local excess coating thicknessthat would interfere with function or as edge tears or spikes that presenta safety hazard because of their sharpness, are grounds for rejection underthe terms of 5.1.5.3 Embrittlement i
36、s a potential condition of steel that iscold-worked, depending on such factors as the steel type(strength level, aging characteristics), thickness, degree of coldwork, and galvanizing process. The galvanizer, the designerand the fabricator shall take precautions against embrittlement.The precautions
37、 to fabricate properly and prepare the materialfor galvanizing to prevent embrittlement are described inPractice A 143.NOTE 4Low service temperatures increase the risk of brittle failure ofall plain carbon steels including those which have been galvanized. Thistemperature embrittling effect varies w
38、ith type of steel. The expectedservice temperature should thus be taken into account when selectingsteels for galvanizing.5.4 Malleable castings shall be of such composition as willpreclude the possibility that they become embrittled by thegalvanizing process, or they shall be either cooled from the
39、anneal, or subsequently heat-treated so as to immunize themagainst embrittlement.5.5 The zinc coating shall adhere tenaciously to the surfaceof the base metal.5.6 If the galvanized material covered by this specificationis bent or otherwise fabricated to the degree that causes the zinccoatings to str
40、etch or compress beyond the limit of elasticity,any cracking or flaking of the coating resulting from thebending or fabricating shall not be cause for rejection.6. Sampling6.1 Test specimens shall be selected at random from eachinspection lot.6.2 The method of selection and sample size shall be agre
41、edupon between the galvanizer and the purchaser. Otherwise, thesample size selected from each lot shall be as follows:Number of Pieces in Lot Sample Size3 or less all4to500 3501 to 1200 51201 to 3200 83201 to 10 000 1310 001 and over 206.3 Aspecimen that fails to conform to a requirement of thisspec
42、ification shall not be used to determine the conformance toother requirements.6.4 The method of sampling for fasteners that are requiredto meet the standards of the Fastener Quality Act is describedin Guide F 1470. Sample quantities and definitions of termi-nology are included in the referenced spec
43、ification.7. Test Methods7.1 Tests shall be made to ensure that the zinc coating isbeing furnished in accordance with this specification and asspecified for the following:7.1.1 Minimum coating weight mass or minimum coatingthickness in 4.3.7.1.2 Finish and appearance in 5.1 and 5.2.7.1.3 Embrittleme
44、nt in 5.3 and 5.4.7.1.4 Adherence in 5.5.7.2 Average Weight Mass of Coating:7.2.1 The average weight mass of the zinc coating shall bedetermined by weighing specimens after pickling and dryingand again after galvanizing unless the method described in7.2.2 is used. The number of specimens that are us
45、ed todetermine the average of an inspection lot shall be derivedfrom Section 6.NOTE 5This method does not take into account the weight mass ofiron reacted from the article that is incorporated into the coating. It willthus underestimate coating weight mass by up to approximately 10 %.Base metal reac
46、tivity will affect the extent of underestimation.7.2.2 In the case of materials inspected after galvanizing,the average weight mass of coating shall be determined bystripping the number of specimens derived in Section 6 inaccordance with Test Method A 90/A 90M, and averaging theresults of the indivi
47、dual specimens, unless the method de-scribed in 7.2.1 is used.7.3 Average Thickness of Coating:7.3.1 In the case of fasteners such as bolts, nuts, and screws,the determination of the thickness of coating shall be made ona portion of the article that does not include any threads.7.3.2 The average thi
48、ckness of coating shall be determinedby magnetic thickness gage in accordance with Practice E 376unless the method described in 7.3.3 is used. The thicknessshall be measured on at least five widely separated spots on aspecimen. No individual spot measurement shall be cause forrejection. If an indivi
49、dual spot does not provide a coatingthickness reading, this spot must be repaired in accordancewith 4.5. The five or more individual coating thicknessmeasurements on a specimen must be averaged to determinethe specimen average coating thickness. The average coatingthickness for the inspection lot is determined by averaging thespecimen average coating thickness values for the number ofspecimens derived from Section 6.7.3.3 The thickness of coating shall be d
