1、Designation: A 153/A 153M 09American 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 () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by age
3、ncies 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 the
4、 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 thi
5、cknessgrade 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 b
6、rackets. 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 stat
7、ed 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 regula
8、tory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A 90/A 90M Test Method for Weight Mass of Coating onIron and Steel Articles with Zinc or Zinc-Alloy CoatingsA 143/A 143M Practice for Safeguarding Against Em-brittlement of Hot-Dip Galvanized Structural Steel Prod-ucts and Proc
9、edure for Detecting EmbrittlementA 780 Practice for Repair of Damaged and Uncoated Areasof Hot-Dip Galvanized CoatingsA 902 Terminology Relating to Metallic Coated Steel Prod-uctsB6 Specification for ZincB 487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examinati
10、on of CrossSectionB 960 Specification for Prime Western Grade-Recycled(PWG-R) ZincE 376 Practice for Measuring Coating Thickness byMagnetic-Field or Eddy-Current (Electromagnetic) Exami-nation MethodsF 1470 Practice for Fastener Sampling for Specified Me-chanical Properties and Performance Inspectio
11、nF 1789 Terminology for F16 Mechanical Fasteners3. Terminology3.1 Definitions:1This specification is under the jurisdiction 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
12、edition approved May 1, 2009. Published May 2009. Originallyapproved in 1933. Last previous edition approved in 2005 as A 153/A 153M - 05.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
13、information, refer to the standards Document Summary page onthe ASTM website.1*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.3.1.1 The following terms and definitions
14、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.3.2 Definitions of Terms Specific to This Standard:3.2.1 average coating thick
15、ness, nthe average of thespecimen coating thickness values for the samples in aninspection 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 othe
16、r than the layergrowth of the coating.3.2.4 individual measurement, nthe reading 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 partscle
17、aned, fluxed and galvanized together at one time in anappropriate container that 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 c
18、onvertthe carbon to graphite, which permits plastic deformation incompression without 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 i
19、ndividual test article upon whichthickness measurements or weight determinations 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
20、 directions) of locations within thespecimen volume.3.2.10 threaded areas, nthe 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 purchas
21、er.4.2 ZincThe zinc used for the coating shall conform toSpecification B6, or Specification B 960, or both, and shall beat least equal to the grade designated 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 alloys
22、hall conform to Specification B6or Specification B 960,orboth.4.2.2 The molten metal in the working volume of thegalvanizing bath shall contain 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,
23、nickel, bismuth, or tin) to the zinc bathto help in the processing of certain reactive steels or to enhance thecosmetic appearance of the finished 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
24、.3 Minimum Coating Weight Mass or Minimum CoatingThicknessThe minimum coating weight mass or the mini-mum coating thickness shall conform to the requirementsprescribed in Table 1 for the material category and thickness ofmaterial in which the article belongs.4.4 Threaded ArticlesThe zinc coating on
25、threads shallnot be subjected to a cutting, rolling, or finishing-tool opera-tion, unless specifically authorized by the purchaser. In order tomeet overtapping allowances, tapping the threads of nuts ortapped holes after galvanizing is not prohibited.4.5 Touch-up and RepairBare spots that are found
26、onparts after galvanizing shall be renovated by use of the methodsfound in Practice A 780 if the following criteria are met. Thebare spots shall 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 thre
27、aded areas of theTABLE 1 Thickness or Weight Mass of Zinc Coating for Various Classes 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, Minimu
28、mCoating Thickness, milsmicrons, MinimumAverage ofSpecimensTestedAnyIndividualSpecimenAverage 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
29、 D):B-1316 in. 4.76 mm and over in thicknessand over 15 in. 381 mm in length2.00 610 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 CF
30、asteners over38 in. 9.52 mm in diameterand similar articles. Washers316 in. and14 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
31、.4 36A 153/A 153M 092piece. The thickness of the repair shall be equal to thesurrounding galvanized coating except for repairs made bypaints containing 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 mat
32、erial, but shall not begreater than 4.0 mils 100 m. Repair thickness measurementsshall be made in accordance with Practice A 780. The galva-nizer shall make repairs unless directed by the purchaser todeliver items unrepaired for subsequent renovation by thepurchaser.5. Workmanship, Finish, and Appea
33、rance5.1 The zinc-coated articles shall be free from uncoatedareas, blisters, flux deposits, dross inclusions, and other typesof projections that would interfere with the intended use of thearticles, or other defects not consistent with good galvanizingpractice.5.2 The zinc coating shall be smooth a
34、nd reasonably uni-form in thickness.NOTE 2Smoothness of surface is a relative term. Minor roughnessthat does not interfere with the intended use 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 thi
35、s specification is applicable to items that are centri-fuged or otherwise handled to remove excess bath metal (see 1.2),irregular coating distribution is not normally encountered. Drainageproblems, which manifest themselves as local excess coating thicknessthat would interfere with function or as ed
36、ge tears or spikes that presenta safety hazard because of their sharpness, are grounds for rejection underthe terms of 5.1.5.3 Embrittlement is a potential condition of steel that iscold-worked, depending on such factors as the steel type(strength level, aging characteristics), thickness, degree of
37、coldwork, and galvanizing process. The galvanizer, the designerand the fabricator shall take precautions against embrittlement.The precautions to fabricate properly and prepare the materialfor galvanizing to prevent embrittlement are described inPractice A 143/A 143M.NOTE 4Low service temperatures i
38、ncrease the risk of brittle failure ofall plain carbon steels including those which have been galvanized. Thistemperature embrittling effect varies with type of steel. The expectedservice temperature should thus be taken into account when selectingsteels for galvanizing.5.4 Malleable castings shall
39、be of such composition as willpreclude the possibility that they become embrittled by thegalvanizing process, or they shall be either cooled from theanneal, or subsequently heat-treated so as to immunize themagainst embrittlement.5.5 The zinc coating shall adhere tenaciously to the surfaceof the bas
40、e metal.5.6 If the galvanized material covered by this specificationis bent or otherwise fabricated to the degree that causes the zinccoatings to stretch or compress beyond the limit of elasticity,any cracking or flaking of the coating resulting from thebending or fabricating shall not be cause for
41、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 agreedupon between the galvanizer and the purchaser. Otherwise, thesample size selected from each lot shall be as follows:Number of Pieces in Lot Sample Si
42、ze3 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 thisspecification shall not be used to determine the conformance toother requirements.6.4 The method of sampling for fasteners that are requiredto meet the sta
43、ndards of the Fastener Quality Act is describedin Guide F 1470. Sample quantities and definitions of termi-nology are included in the referenced specification.7. Test Methods7.1 Tests shall be made to ensure that the zinc coating isbeing furnished in accordance with this specification and asspecifie
44、d 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 Embrittlement 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 wei
45、ghing specimens after pickling and dryingand again after galvanizing unless the method described in7.2.2 is used. The number of specimens that are used todetermine the average of an inspection lot shall be derivedfrom Section 6.NOTE 5This method does not take into account the weight mass ofiron reac
46、ted from the article that is incorporated into the coating. It willthus underestimate coating weight mass by up to approximately 10 %.Base metal reactivity 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
47、 determined bystripping the number of specimens derived in Section 6 inaccordance with Test Method A 90/A 90M, and averaging theresults of the individual 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
48、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 thickness of coating shall be determinedby magnetic thickness gage in accordance with Practice E 376unless the method described in 7.3.3 is used. The thic
49、knessshall be measured on at least five widely separated spots on aspecimen. No individual spot measurement shall be cause forrejection. If an individual 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 determin
