1、Designation: A755/A755M 11Standard 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 ind
2、icates 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 o
3、f the Department of Defense.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 coils, cut lengths, and formed cut lengths. Build-ing products inclu
4、de 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 Coating systems supplied under this specification con-sist of a prim
5、er 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: polyester,silicone polyester, acrylic, fluoropolymer, plastisol, or pol
6、yure-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. Each systemshall be used independently of each other.1.5 Unless t
7、he 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 those in tables and figures, shall not beconsidered as requireme
8、nts 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 practices and determine the applica-bility of regulatory limitations pr
9、ior 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 (Galvannealed)by the Hot-Dip ProcessA792/A792M Specification for Steel Sh
10、eet, 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 Specification for General Requirements forSteel Sheet, Metallic-Coated by t
11、he 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 Practice for Operating Salt Spray (Fog) ApparatusD522 Test Methods
12、for Mandrel Bend Test of AttachedOrganic CoatingsD523 Test Method for Specular GlossD659 Method for Evaluating Degree of Chalking of Exte-rior Paints3D714 Test Method for Evaluating Degree of Blistering ofPaintsD822 Practice for Filtered Open-Flame Carbon-Arc Expo-sures of Paint and Related Coatings
13、D870 Practice for Testing Water Resistance of CoatingsUsing Water Immersion1This specification 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 Nov. 1, 201
14、1. Published November 2011. Originallyapproved in 1978. Last previous edition approved in 2008 as A755/A755M 03(2008). DOI: 10.1520/A0755_A0755M-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandar
15、ds volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive
16、, PO Box C700, West Conshohocken, PA 19428-2959, United States.D1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1654 Test Method for Evaluation of Painted or CoatedSpecimens Subjected to Corrosive EnvironmentsD1735 Practice for Testing Water Resistance o
17、f CoatingsUsing Water Fog ApparatusD2240 Test Method for Rubber PropertyDurometerHardnessD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD2247 Practice for Testing Water Resistance of Coatings in100 % Relative HumidityD2370 Test Me
18、thod for Tensile Properties of Organic Coat-ingsD3359 Test Methods for Measuring Adhesion by Tape TestD3363 Test Method for Film Hardness by Pencil TestD4145 Test Method for Coating Flexibility of PrepaintedSheetD4214 Test Methods for Evaluating the Degree of Chalkingof Exterior Paint FilmsG85 Pract
19、ice for Modified Salt Spray (Fog) Testing3. Terminology3.1 Definitions:3.1.1 SubstrateFor definitions 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 andmethacryli
20、c acids, and styrene; they contain one or morefunctional groups such as amide, hydroxy, or carboxy and formthermosetting systems on baking by cross-linking with them-selves, or amino or epoxy resins.3.1.2.2 conversion coating, na chemical treatment, nor-mally applied to a metal surface prior to fina
21、l finishing, whichis designed to react with and modify the metal to produce asurface suitable 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 sy
22、stems on baking.3.1.2.4 fluorocarbon, npolymers based on fluorocarbonresins made by the polymerization 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 thermo
23、settingsystems on baking.3.1.2.5 plastisol, na dispersion of finely divided vinylresin in plasticizers; 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
24、diols (dihydric alcohols), alsocalled oil-alkyds; they are modified by the addition reaction ofmonomers 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
25、an acrylic polyol or polyester polyol with anisocyanate-containing compound to produce thermosettingsystems 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
26、 purpose, and the coating system being used.3.1.2.9 silicone polyester, na polymer which is the 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 thermos
27、etting systems on baking.3.1.3 Coating Characteristics:3.1.3.1 chalking, vthe formation on a pigmented 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 t
28、heeffect of ultraviolet radiation.3.1.3.3 gloss, nthe luster, shininess, or reflecting ability 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 painta
29、nd other coatings are applied and baked onto a moving stripof steel sheet.3.2.2.1 DiscussionRolls 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
30、mil, na unit of length equal to 0.001 in. 25.4 m,used for describing the thickness of paint coatings.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 vario
31、us shapes by a series of contoured steelrolls.3.2.6 top side, nthe side of the prepainted sheet which isexposed to weathering.3.2.7 washcoat, na thin organic coating, usually a poly-ester, applied to the back or unexposed side of prepainted sheet(also known as a backercoat).3.2.7.1 DiscussionThis pi
32、gmented/nonpigmented coatingis applied for such reasons as protection of the topcoat 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 asf
33、ollows:4.1.1 Zinc-Coated (Galvanized)Specifications A653/A653M and A1063/A1063M.4.1.2 Zinc-5 % Aluminum Alloy-CoatedSpecificationA875/A875M.A755/A755M 1124.1.3 55 % Aluminum-Zinc Alloy-CoatedSpecificationA792/A792M.4.1.4 Aluminum CoatedSpecification A463/A463M.4.1.5 Zinc-Aluminum-Magnesium Alloy-Coa
34、tedSpecification A1046/A1046M.4.1.6 Each of the above-listed metallic-coated sheet speci-fications 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
35、based on the type of environmentwhere the building is erected, the recommended minimumcoating mass designations for use in exterior exposed buildingapplications are:Metallic Coating Minimum Recommended CoatingA653/A653M Zinc-Coated (Galvanized) G90 Z275A875/A875M Zinc-5 % Aluminum Alloy-Coated GF75
36、ZGF225A792/A792M 55 % Aluminum-Zinc Alloy-Coated AZ50 AZM150A463/A463M Aluminum Coated T2 65 T2 200A1046/A1046M Zinc-Aluminum-Magnesium Coated ZM75 ZMM220A1063/A1063M Zinc-Coated (Galvanized) G90 Z275These minimum coating weight mass designations areimportant to attain the normally expected long-ter
37、m productlife in the application. Exceptions to these minimum designa-tions can be considered when 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 corrosiv
38、e environ-ments, the user should consider specifying a coating designa-tion with a heavier coating weight 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 P
39、rimers: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 Polyester.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 wil
40、l be specified if agreed upon betweenthe producer and the purchaser (see Note 2).5. Ordering Information5.1 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 thi
41、ckness of the organic system is in addition tothe substrate (base steel and metallic coating).5.2 Orders 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 desi
42、gnation and year of issue, as A755 forinch-pound units or A755M for SI units,5.2.3 ASTM specification number of metallic coated sub-strate, 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
43、.2.6 Metallic coating finish (such as regular, minimizedspangle, extra smooth, or minimized spangle-extra 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 w
44、ill consist of a primer and a washcoat, or thesame coating as the topside) (see 7.4.2),5.2.9 Protection 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.5.2.1
45、1 Coil size requirement: maximum outside diameter,acceptable inside diameter, and maximum weight mass,5.2.12 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 Supplement
46、ary Require-ments section in Specification A924/A924M), this requirementshall be specified in the order 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, AS
47、TM A653/A653M, SS, Grade 40 with G90 coating, extrasmooth, Top Side Primer, 0.25 mil thickness plus Gold 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 ou
48、tside diameter, 20 000 pound max weightcoil for roll-formed exterior building siding.Prepainted steel sheet, 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 Fluoro
49、polymer, 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,instead of using the generic terms listed in 4.2, it is permissible tosubstitute trade name terminology as published by various coating andprepainted sheet suppliers. These trade name coatings are brand
