1、Designation: A755/A755M 161Standard Specification forSteel Sheet, Metallic Coated by the Hot-Dip Process andPrepainted by the Coil-Coating Process for ExteriorExposed Building Products1This standard is issued under the fixed designation A755/A755M; the number immediately following the designation in
2、dicates 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 agencies
3、of the U.S. Department of Defense.1NOTEText in Note 3 was corrected editorially in June 2016.1. Scope*1.1 This specification covers steel sheet metallic coated bythe hot-dip process and coil-coated with organic films forexterior exposed building products. Sheet of this designation isfurnished in coi
4、ls, cut lengths, and formed cut lengths. Build-ing products include corrugated and various types of roll andbrake-formed configurations.1.2 The substrate is available in several different metallic-coated steel sheet products as enumerated in 4.1, depending onthe requirements of the purchaser.1.3 Coa
5、ting systems supplied under this specification con-sist of a primer coat covered by various types and thicknessesof top coats. The combination of primer and top coat is classedas either a two-coat thin-film system or as a two-coat (or more)thick-film system. Typical top-coating materials are: polyes
6、ter,silicone polyester, acrylic, fluoropolymer, plastisol, or polyure-thane.1.4 This specification is applicable to orders in eitherinch-pound units (as A755) or SI units as A755M. Values ininch-pound units and SI units are not necessarily equivalent.Within the text, SI units are shown in brackets.
7、Each systemshall be used independently of each other.1.5 Unless the order specifies the “M” designation (SI units)the product shall be furnished to inch-pound units.1.6 The text of this specification references notes andfootnotes that provide explanatory material. These notes andfootnotes, excluding
8、 those in tables and figures, shall not beconsidered as requirements of this specification.1.7 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 practi
9、ces and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A463/A463M Specification for Steel Sheet, Aluminum-Coated, by the Hot-Dip ProcessA653/A653M Specification for Steel Sheet, Zinc-Coated(Galvanized) or Zinc-Iron Alloy-Coated (Galvann
10、ealed)by the Hot-Dip ProcessA792/A792M Specification for Steel Sheet, 55 %Aluminum-Zinc Alloy-Coated by the Hot-Dip ProcessA875/A875M Specification for Steel Sheet, Zinc-5 % Alu-minum Alloy-Coated by the Hot-Dip ProcessA902 Terminology Relating to Metallic Coated Steel Prod-uctsA924/A924M Specificat
11、ion for General Requirements forSteel Sheet, Metallic-Coated by the Hot-Dip ProcessA1046/A1046M Specification for Steel Sheet, Zinc-Aluminum-Magnesium Alloy-Coated by the Hot-Dip Pro-cessA1063/A1063M Specification for Steel Sheet, Twin-RollCast, Zinc-Coated (Galvanized) by the Hot-Dip ProcessB117 Pr
12、actice for Operating Salt Spray (Fog) ApparatusD522 Test Methods for Mandrel Bend Test of AttachedOrganic CoatingsD523 Test Method for Specular GlossD659 Method for Evaluating Degree of Chalking of ExteriorPaints (Withdrawn 1990)3D714 Test Method for Evaluating Degree of Blistering ofPaints1This spe
13、cification is under the jurisdiction of ASTM Committee A05 onMetallic-Coated Iron and Steel Products and is the direct responsibility ofSubcommittee A05.11 on Sheet Specifications.Current edition approved May 1, 2016. Published May 2016. Originallyapproved in 1978. Last previous edition approved in
14、2015 as A755/A755M 15.DOI: 10.1520/A0755_A0755M-16E01.2For 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.3The la
15、st approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D822 Practice for Filtered Open-Flame Carbon
16、-Arc Expo-sures of Paint and Related CoatingsD870 Practice for Testing Water Resistance of CoatingsUsing Water ImmersionD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic
17、Coatings Applied toa Ferrous Base (Withdrawn 2006)3D1654 Test Method for Evaluation of Painted or CoatedSpecimens Subjected to Corrosive EnvironmentsD1735 Practice for Testing Water Resistance of CoatingsUsing Water Fog ApparatusD2244 Practice for Calculation of Color Tolerances andColor Differences
18、 from Instrumentally Measured ColorCoordinatesD2247 Practice for Testing Water Resistance of Coatings in100 % Relative HumidityD3359 Test Methods for Measuring Adhesion by Tape TestD3363 Test Method for Film Hardness by Pencil TestD4145 Test Method for Coating Flexibility of PrepaintedSheetD4214 Tes
19、t Methods for Evaluating the Degree of Chalkingof Exterior Paint FilmsD5796 Test Method for Measurement of Dry Film Thicknessof Thin-Film Coil-Coated Systems by Destructive MeansUsing a Boring DeviceG85 Practice for Modified Salt Spray (Fog) Testing3. Terminology3.1 Definitions:3.1.1 SubstrateFor de
20、finitions of terms relating to thesubstrate, see Terminology A902.3.1.2 Coatings:3.1.2.1 acrylic, na polymer based on resins prepared froma combination of acrylic and methacrylic esters, acrylic andmethacrylic acids, and styrene; they contain one or morefunctional groups such as amide, hydroxy, or c
21、arboxy and formthermosetting systems on baking by cross-linking withthemselves, or amino or epoxy resins.3.1.2.2 conversion coating, na chemical treatment, nor-mally applied to a metal surface prior to final finishing, whichis designed to react with and modify the metal to produce asurface suitable
22、for painting.3.1.2.3 epoxy, npolymers based on epoxy resins, whichare the reaction product of epichlorohydrin and biphenol-Aandare cross-linked with amino or urea-formaldehyde resins toform thermosetting systems on baking.3.1.2.4 fluorocarbon, npolymers based on fluorocarbonresins made by the polyme
23、rization of vinyl fluoride monomer(PVF) or vinylidene fluoride monomer (PVF2); these resins areformulated into coatings by dispersion of finely divided par-ticles in dispersants and diluents and form thermosettingsystems on baking.3.1.2.5 plastisol, na dispersion of finely divided vinylresin in plas
24、ticizers; during the baking process, the resinparticles are solvated by the plasticizer and fuse into acontinuous film.3.1.2.6 polyester, na polymer based on the condensationproducts of polybasic acids and diols (dihydric alcohols), alsocalled oil-alkyds; they are modified by the addition reaction o
25、fmonomers such as styrene or acrylic esters; polyester resins arecross-linked with amino resins to form thermosetting systemson baking.3.1.2.7 polyurethane, na polymer produced by the addi-tion reaction of an acrylic polyol or polyester polyol with anisocyanate-containing compound to produce thermos
26、ettingsystems on baking.3.1.2.8 primer, nthe first complete layer of paint of acoating system applied to an uncoated surface; the type ofprimer varies with the type of surface and its condition, theintended purpose, and the coating system being used.3.1.2.9 silicone polyester, na polymer which is th
27、e reac-tion product between an organo-siloxane intermediate and analkyd resin, or a cold blend of a silicone resin and a compatiblealkyd resin; these resins are cross-linked with amino resins toform thermosetting systems on baking.3.1.3 Coating Characteristics:3.1.3.1 chalking, vthe formation on a p
28、igmented coatingof a friable powder evolved from the film itself at or justbeneath the surface.3.1.3.2 fade, va loss in color intensity experienced bypigmented organic coatings over time, generally due to theeffect of ultraviolet radiation.3.1.3.3 gloss, nthe luster, shininess, or reflecting ability
29、 ofa surface.3.2 Definitions of Terms Specific to This Standard:3.2.1 bottom side, nthe side of prepainted sheet oppositethe exposed weathering side.3.2.2 coil coating, va continuous process by which paintand other coatings are applied and baked onto a moving stripof steel sheet.3.2.2.1 DiscussionRo
30、lls are used to pick up, meter, anddeposit the liquid coating onto the moving strip and are alsoused to support the strip through the line. The product of thisprocess is called prepainted steel sheet.3.2.3 mil, na unit of length equal to 0.001 in. 25.4 m,used for describing the thickness of paint co
31、atings.3.2.4 paint, n of coil coating, an organic liquid,pigmented/nonpigmented, which is converted to a solid film bybaking.3.2.5 roll former, nan apparatus that forms a continuousstrip of metal into various shapes by a series of contoured steelrolls.3.2.6 top side, nthe side of the prepainted shee
32、t which isexposed to weathering.3.2.7 washcoat, na thin organic coating, usually apolyester, applied to the back or unexposed side of prepaintedsheet (also known as a backercoat).A755/A755M 16123.2.7.1 DiscussionThis pigmented/nonpigmented coatingis applied for such reasons as protection of the topc
33、oat while incoil form, interior appearance, and lubrication during rollforming.4. Classification4.1 The substrate shall conform to all requirements of theappropriate specification for the steel sheet product ordered asfollows:4.1.1 Zinc-Coated (Galvanized)Specifications A653/A653M and A1063/A1063M.4
34、.1.2 Zinc-5 % Aluminum Alloy-CoatedSpecificationA875/A875M.4.1.3 55 % Aluminum-Zinc Alloy-CoatedSpecificationA792/A792M.4.1.4 Aluminum CoatedSpecification A463/A463M.4.1.5 Zinc-Aluminum-Magnesium Alloy-CoatedSpecification A1046/A1046M.4.1.6 Each of the above-listed metallic-coated sheet speci-ficati
35、ons describes the range of available coating designations.The particular designation selected is related to the expectedperformance of the exterior exposed building product. Al-though there are exceptions based on the type of environmentwhere the building is erected, the recommended minimumcoating m
36、ass designations for use in exterior exposed buildingapplications are:Metallic Coating Minimum RecommendedCoatingA653/A653M Zinc-Coated (Galvanized) G90 Z275A875/A875M Zinc-5 % Aluminum Alloy-Coated GF75 ZGF225A792/A792M 55 % Aluminum-Zinc Alloy-Coated AZ50 AZM150A463/A463M Aluminum Coated T2 65 T2
37、200A1046/A1046M Zinc-Aluminum-MagnesiumCoatedZM75 ZMM220A1063/A1063M Zinc-Coated (Galvanized) G90 Z275These minimum coating weight mass designations areimportant to attain the normally expected long-term productlife in the application. Exceptions to these minimum designa-tions can be considered when
38、 the environmental conditions areof low corrosive potential, such as a very dry climate. In thesecases, a lower coating weight mass, for example, G60 Z180may be appropriate. Similarly, for very corrosiveenvironments, the user should consider specifying a coatingdesignation with a heavier coating wei
39、ght mass.4.2 The organic coating typically consists of a primer and atopcoat on the top (exposed) side and washcoat on the bottom(unexposed) side. Typical primers and topcoats are as follows:4.2.1 Primers:4.2.1.1 Epoxy.4.2.1.2 Acrylic.4.2.1.3 Polyurethane.4.2.1.4 Polyester4.2.2 Top Coats:4.2.2.1 Pol
40、yester.4.2.2.2 Silicone polyester.4.2.2.3 Acrylic.4.2.2.4 Fluoropolymer.4.2.2.5 Plastisol.4.2.2.6 Polyurethane.4.2.3 Washcoats or Backercoats:4.2.3.1 Polyester.4.2.3.2 Acrylic.4.3 Other coatings will be specified if agreed upon betweenthe producer and the purchaser (see Note 2).5. Ordering Informati
41、on5.1 The coated flat sheet covered by this specification isproduced on continuous lines to decimal thickness only. Thethickness of the sheet includes the base steel and the metalliccoating. The thickness of the organic system is in addition tothe substrate (base steel and metallic coating).5.2 Orde
42、rs for material under this specification shall includethe following information, as applicable, to describe therequired product adequately:5.2.1 Product name (prepainted steel sheet),5.2.2 ASTM designation and year of issue, as A755 forinch-pound units or A755M for SI units,5.2.3 ASTM specification
43、number of metallic coatedsubstrate, steel sheet designation, and, if applicable, type (andgrade, if required),5.2.4 Metallic coating type (see 4.1),5.2.5 Metallic coating weight mass designation,5.2.6 Metallic coating finish (such as regular, minimizedspangle, extra smooth, or minimized spangle-extr
44、a smooth),5.2.7 Organic coating system designation (see 4.2 or 4.3),5.2.8 Dry organic film thickness top side and bottom side(the top side will consist of a primer and topcoat and thebottom side will consist of a primer and a washcoat, or thesame coating as the topside) (see 7.4.2),5.2.9 Protection
45、required (waxed or strippable coating),5.2.10 Dimensions (thickness, width, either flat or formed(overall or cover) and length (if cut length) and, if applicable,type of formed configuration.5.2.11 Coil size requirement: maximum outside diameter,acceptable inside diameter, and maximum weight mass,5.
46、2.12 Cut length requirement: maximum lift weight mass,5.2.13 Special requirements, if any, and5.2.13.1 When the purchaser requires thickness tolerancesfor38-in. 10-mm edge distance (see Supplementary Require-ments section in Specification A924/A924M), this requirementshall be specified in the order
47、of contract.5.2.14 Application (part identification and description).NOTE 1A typical ordering description is as follows:Prepainted steel sheet, ASTM A755 _ on zinc-coated (galvanized)substrate, ASTM A653/A653M, SS, Grade 40 with G90 coating, extrasmooth, Top Side Primer, 0.25 mil thickness plus Gold
48、 Silicone-Polyester,0.8 mil thickness, Bottom Side Primer, 0.25 mil thickness plus Washcoat,0.3 mil thickness, 0.019 in. min thickness by 42 in. width by Coil, 24 in.inside diameter, 52 in. max outside diameter, 20 000 pound max weightcoil for roll-formed exterior building siding.Prepainted steel sh
49、eet, ASTM A755M _ on 55 % aluminum-zincalloy-coated substrate, ASTM A792/A792M, CS Type A with AZM150aluminum-zinc alloy coating, extra smooth, Top Side Primer, 0.006 mmthickness plus White Fluoropolymer, 0.020 mm thickness, Bottom SidePrimer, 0.006 mm thickness plus Washcoat, 0.008 mm thickness, 0.80 mmthickness by 1000 mm width by Coil, 600 mm inside diameter, 1320 mmmax outside diameter, 4500 kg max coil for roll-formed exterior siding.NOTE 2When specifying the organic coating system designation,ins
