1、Designation: A1072/A1072M 11Standard Specification forZinc-5 % Aluminum (Hot-Dip) Coatings on Iron and SteelProducts1This standard is issued under the fixed designation A1072/A1072M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision,
2、the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the requirements for zinc-5 %aluminum coated, by the hot-dip process on iron and
3、 steelproducts. The coating may also contain small amounts ofelements other than zinc and aluminum that are intended toimprove processing and the characteristics of the coatedproduct. These metallic coatings include zinc- 5 %-aluminum(Zn-5Al), zinc-5 %-aluminum-mischmetal (Zn-5Al-MM) andzinc-5 %-alu
4、minum-magnesium (Zn- %Al-Mg).1.2 This specification covers both un-fabricated productsand fabricated products, for example, assembled steel products,structural steel fabrications, large tubes already bent or weldedbefore hot-dip coating, and wire work fabricated from un-coated steel wire. This speci
5、fication, also, covers steel forgingsand iron castings incorporated into pieces fabricated, beforehot-dip coating or which are too large to be centrifuged (orotherwise handled to remove excess molten bath metal).1.3 Fabricated reinforcing steel bar assemblies are coveredby the present specification.
6、1.4 This specification is applicable to orders in eitherinch-pound units (as A1072) or SI units (as A1072M). Inch-pound units and SI units are not necessarily exact equivalents.Within the text of this specification and where appropriate, SIunits are shown in parentheses. Each system shall be usedind
7、ependently of the other without combining values in anyway. In the case of orders in SI units, all testing and inspectionshall be done using the metric equivalent of the test orinspection method as appropriate. In the case of orders in SIunits, such shall be stated to the hot-dip coater when the ord
8、eris placed.2. Referenced Documents2.1 ASTM Standards:2A47/A47M Specification for Ferritic Malleable Iron Cast-ingsA90/A90M Test Method for Weight Mass of Coating onIron and Steel Articles with Zinc or Zinc-Alloy CoatingsA143/A143M Practice for Safeguarding Against Embrittle-ment of Hot-Dip Galvaniz
9、ed Structural Steel Products andProcedure for Detecting EmbrittlementA384/A384M Practice for Safeguarding Against Warpageand Distortion During Hot-Dip Galvanizing of Steel As-sembliesA385 Practice for Providing High-Quality Zinc Coatings(Hot-Dip)A780 Practice for Repair of Damaged and Uncoated Areas
10、of Hot-Dip Galvanized CoatingsA902 Terminology Relating to Metallic Coated Steel Prod-uctsB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of CrossSectionB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB750 Specification for G
11、ALFAN (Zinc-5 % Aluminum-Mischmetal) Alloy in Ingot Form for Hot-Dip CoatingsE376 Practice for Measuring Coating Thickness byMagnetic-Field or Eddy-Current (Electromagnetic) TestingMethods1This specification is under the jurisdiction of ASTM Committee A05 onMetallic-Coated Iron and Steel Products an
12、d is the direct responsibility ofSubcommittee A05.13 on Structural Shapes and Hardware Specifications.Current edition approved Nov. 15, 2011. Published December 2011.DOI:10.1520/A1072_A1072M-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at s
13、erviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3. Terminology3.1 DefinitionsThe following terms and
14、 definitions arespecific to this specification. Terminology A902 contains otherterms and definitions relating to metallic-coated steel products.3.2 Definitions of Terms Specific to This Standard:3.2.1 average coating thickness, nthe average of threespecimen coating thicknesses.3.2.2 black, adjdenote
15、s the condition of not galvanized orotherwise coated. For purposes of this specification the word“black” does not refer to the color or condition of surface, or toa surface deposit or contamination.3.2.3 coating thickness grade, nthe numerical value fromTable 1 at the intersection of a material cate
16、gory and athickness range.3.2.4 gross dross inclusions, nthe iron/aluminum interme-tallics present in a galvanized coating in a form other thanfinely dispersed pimples.3.2.4.1 DiscussionThese inclusions would create an ex-posed steel spot if they were removed from the coating. Theseinclusions are ra
17、ised surfaces and are easily knocked offthrough contact with lifting straps or chains, tools, fixtures, orother galvanized parts.3.2.5 material category, nthe general class or type ofmaterial or process of manufacture, or both, that nominallydescribes a unit of product, or from which a unit of produ
18、ct ismade. For example, bar grating belongs to the category “strip,”handrail belongs to the category “pipe,” etc.3.2.6 multi-specimen article, na unit of product whosesurface area is greater than 160 in.2100 000 mm2. Forthickness testing purposes, articles whose surface area isgreater than 160 in.2a
19、re subdivided into three continuous localsections, nominally equal in surface area, each of whichconstitutes a specimen. In the case of any such local sectioncontaining more than one material category or steel thicknessrange as delineated in Table 1, that section will contain morethan one specimen (
20、see Fig. 1).3.2.7 sample, na collection of individual units of productfrom a single lot selected in accordance with Section 7, andintended to represent that lot for acceptance. If a sample istaken as representing the lot for acceptance, the sample shall betaken at random from the lot without regard
21、to the perceivedquality or appearance of any individual unit in the lot beingsampled. The sample consists of one or more test articles.3.2.8 single-specimen article, na unit of product whosesurface area is equal to or less than 160 in.2100 000 mm2orthat is centrifuged or otherwise similarly handled
22、in thegalvanizing process to remove excess galvanizing bath metal(free zinc). For thickness testing purposes, the entire surfacearea of each unit of product constitutes a specimen. In the caseof any such article containing more than one material categoryor steel thickness, that article will contain
23、more than onespecimen (see Fig. 1).3.2.9 specimen, nthe surface of an individual test articleor a portion of a test article, upon which thickness measure-ments are to be performed, which is a member of a lot, or amember of a sample representing that lot. For magneticthickness measurements, specimen
24、excludes any area of thesurface which is subject to processes (such as flame cutting,machining, threading, etc.) that can be expected to result insurface conditions not representative of the general surfacecondition of the test article, or is disqualified by the measure-ment method. For a unit of pr
25、oduct whose surface area is equalto or less than 160 in.2100 000 mm2, the entire surface areaof each test article constitutes a specimen. In the case of anarticle containing more than one material category or steel, thatarticle will contain more than one specimen, as appropriate(see Fig. 1).3.2.10 s
26、pecimen coating thickness, nthe average thick-ness from no less than five test measurements on a specimen,when each measurement location is selected to provide thewidest dispersion (in all applicable directions) of locations forthe steel category of the test article within the confines of thespecime
27、n volume.3.2.11 test article, nan individual unit of product that is amember of the sample and that is examined for conformance toa part of this specification.4. Ordering Information4.1 Orders for coatings provided under this specificationshall include the following:4.1.1 Quantity (number of pieces
28、to be galvanized) and totalweight.4.1.2 Description (type and size of products) and weight.4.1.3 ASTM specification designation and year of issue.4.1.4 Material identification (see 5.1) and surface conditionor contamination.4.1.5 Sampling plan, if different from 7.3.4.1.6 Special test requirements (
29、see 8.1).4.1.7 Special requirements (special stacking, heavier coat-ing weight, etc.).4.1.8 Tagging or piece identification method.5. Materials and Manufacture5.1 Steel or IronThe specification, grade, or designationand type and degree of surface contamination of the iron orsteel in articles to be h
30、ot-dip coated shall be supplied by thepurchaser to the hot-dip coater prior to coating.5.2 FabricationThe design and fabrication of the productto be hot-dip coated are the responsibilities of the designer andthe fabricator. Practices A143/A143M, A384/A384M, andA385 provide guidance for steel fabrica
31、tion for optimum hotdip coating and shall be complied with in both design andfabrication. Consultation between the designer, fabricator, andcoater at appropriate stages in the design and fabricationprocess will reduce future problems.TABLE 1 Guide to Conversion Between Coating Weight Massand Thickne
32、ssA875/A875M Zinc-5 % Aluminum Alloy-Coated Sheet(Assume 1.00 oz/ft2= 305 g/m2= 1.75 mils)Coating Weight Mass Coating Thicknessoz/ft2g/m2milm1.00 305 1.75 44.60.00328 1.00 0.00574 0.1460.570 174 1.00 25.40.0224 6.83 0.0394 1.00A1072/A1072M 1125.3 CastingsThe composition and heat treatment of ironand
33、 steel castings shall conform to specifications designated bythe purchaser. Some types of castings have been known toshow potential problems with predisposition to being em-brittled during the normal thermal cycle of hot-dip coating. Itis the responsibility of the purchaser to heat treat or otherwis
34、eallow for the possibility of such embrittling phenomena. Therequirements for malleable iron castings to be hot-dip coatedshall be as stated in Specification A47/A47M.5.4 ZincThe zinc-aluminum alloy used in the hot-dipcoating bath shall conform to Specification B750. If a zinc-aluminum alloy is used
35、 as the primary feed to the molten bath,then the base material used to make that alloy shall conform toSpecification B750.5.5 Coating Bath AnalysisThe molten metal in the work-ing volume of the galvanizing bath shall contain not less thanan average value of 93 % zinc by weight.FIG. 1 Single- and Mul
36、ti-Specimen ArticlesA1072/A1072M 1135.5.1 Bath Metal used in bath hot-dip Zn-5Al-MM alloycoating shall meet the chemical composition limits specified inSpecification B750.5.5.2 The determination of chemical composition shall be inaccordance with suitable chemical, ICP spectrometric, or othermethods.
37、6. Coating Properties6.1 Coating ThicknessThe minimum average thickness ofcoating for all specimens tested shall be a minimum of 0.39 mil10 m. The minimum average thickness of coating for anyindividual specimen shall be 0.3 mil 8 m.6.2 FinishThe coating shall be continuous (except asprovided below),
38、 and as reasonably smooth and uniform inthickness as the weight, size, shape of the item, and necessaryhandling of the item during the dipping and draining operationsat the hot-dip coating kettle will permit. Except for local excesscoating thickness which would interfere with the use of theproduct,
39、or make it dangerous to handle (edge tears or spikes),rejection for nonuniform coating shall be made only for plainlyvisible excess coating not related to design factors such asholes, joints, or special drainage problems (see Note 6). Sincesurface smoothness is a relative term, minor roughness thatd
40、oes not interfere with the intended use of the product, orroughness that is related to the as-received (ungalvanized)surface condition, steel chemistry, or steel reactivity to zincshall not be grounds for rejection (see Note 7). Surfaceconditions related to deficiencies related to design, detailing,
41、 orfabrication as addressed by Practice A385 shall not be groundsfor rejection. Surfaces that remain uncoated after galvanizingshall be renovated in accordance with the methods in PracticeA780 unless directed by the purchaser to leave the uncoatedareas untreated for subsequent renovation by the purc
42、haser.6.2.1 Each area subject to renovation shall be 1 in. 25 mmor less in its narrowest dimension.6.2.2 The total area subject to renovation on each articleshall be no more than12 of 1 % of the accessible surface areato be coated on that article, or 36 in.2per short ton 256 cm2permetric ton of piec
43、e weight, whichever is less.NOTE 1Inaccessible surface areas are those which cannot be reachedfor appropriate surface preparation and application of repair materials asdescribed in Practice A780. Such inaccessible areas, for example, wouldbe the internal surfaces of certain tanks, poles, pipes, tube
44、s, and so forth.6.2.3 The thickness of renovation shall be a minimum of 0.3mil 8 m, except that for renovation using zinc rich paints,the thickness of renovation shall be at least 1 mil 25 m.6.2.4 When areas requiring renovation exceed the criteriapreviously provided, or are inaccessible for repair,
45、 the coatingshall be rejected.NOTE 2The requirements for the finish of a zinc aluminum coatedproduct address themselves to a visual type of inspection. They do notaddress the matter of measured coating thickness variations that can beencountered because of different steels or different thicknesses o
46、f a givensteel being used in an assembly.NOTE 3Items which are prepared for hot-dip coating by abrasivecleaning will generally develop a thicker coating with a moderatelyrougher surface.6.3 Threaded Components in AssembliesThe zinc coatingon external threads shall not be subjected to a cutting, roll
47、ing,or finishing tool operation, unless specifically authorized by thepurchaser. Internal threads are not prohibited from beingtapped or re-tapped after hot-dip coating.6.4 AppearanceUpon shipment from the galvanizing fa-cility, galvanized articles shall be free from uncoated areas,blisters, flux de
48、posits, and gross dross inclusions. Lumps,projections, globules, or heavy deposits of zinc which willinterfere with the intended use of the material will not bepermitted. Plain holes of12-in. 12.5-mm diameter or moreshall be clean and reasonably free from excess zinc-aluminummetal. Marks in the coat
49、ing caused by tongs or other items usedin handling the article during the hot-dip coating operationshall not be cause for rejection unless such marks have exposedthe base metal and the bare metal areas exceed allowablemaximums from 6.2.1 and 6.2.2. The pieces shall be handledso that after hot-dip coating they will not freeze together oncooling.NOTE 4Depending upon product design or material thickness, orboth, filming or excess zinc-aluminum buildup in plain holes of less than12-in. 12.5-mm diameter may occur that requir
