1、Designation: A755/A755M 11A755/A755M 15Standard 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 de
2、signation 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
3、by agencies of the U.S. Department of Defense.1. Scope*1.1 This specification covers steel sheet metallic coated by the hot-dip process and coil-coated with organic films for exteriorexposed building products. Sheet of this designation is furnished in coils, cut lengths, and formed cut lengths. Buil
4、ding productsinclude corrugated and various types of roll and brake-formed configurations.1.2 The substrate is available in several different metallic-coated steel sheet products as enumerated in 4.1, depending on therequirements of the purchaser.1.3 Coating systems supplied under this specification
5、 consist of a primer coat covered by various types and thicknesses of topcoats. The combination of primer and top coat is classed as either a two-coat thin-film system or as a two-coat (or more) thick-filmsystem. Typical top-coating materials are: polyester, silicone polyester, acrylic, fluoropolyme
6、r, plastisol, or polyurethane.1.4 This specification is applicable to orders in either inch-pound units (as A755) or SI units as A755M. Values in inch-poundunits and SI units are not necessarily equivalent. Within the text, SI units are shown in brackets. Each system shall be usedindependently of ea
7、ch 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 and footnotes that provide explanatory material. These notes and footnotes,excluding those in tables and figures, shall not be
8、 considered as requirements of this specification.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of re
9、gulatorylimitations 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 (Galvannealed) by theHot-Dip ProcessA792/A792M Spe
10、cification for Steel Sheet, 55 % Aluminum-Zinc Alloy-Coated by the Hot-Dip ProcessA875/A875M Specification for Steel Sheet, Zinc-5 % Aluminum Alloy-Coated by the Hot-Dip ProcessA902 Terminology Relating to Metallic Coated Steel ProductsA924/A924M Specification for General Requirements for Steel Shee
11、t, Metallic-Coated by the Hot-Dip ProcessA1046/A1046M Specification for Steel Sheet, Zinc-Aluminum-Magnesium Alloy-Coated by the Hot-Dip ProcessA1063/A1063M Specification for Steel Sheet, Twin-Roll Cast, Zinc-Coated (Galvanized) by the Hot-Dip ProcessB117 Practice for Operating Salt Spray (Fog) Appa
12、ratusD522 Test Methods for Mandrel Bend Test of Attached Organic Coatings1 This specification is under the jurisdiction ofASTM Committee A05 on Metallic-Coated Iron and Steel Products and is the direct responsibility of Subcommittee A05.11on Sheet Specifications.Current edition approved Nov. 1, 2011
13、Jan. 1, 2015. Published November 2011January 2015. Originally approved in 1978. Last previous edition approved in 20082011as A755/A755M 03A755/A755M 11.(2008). DOI: 10.1520/A0755_A0755M-11.10.1520/A0755_A0755M-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Cus
14、tomer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to t
15、he previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary
16、 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 States1D523 Test Method for Specular GlossD659 Method for Evaluating Degree of Chalking of Exterior Paints (Withdrawn 1990)3D714 Test Meth
17、od for Evaluating Degree of Blistering of PaintsD822 Practice for Filtered Open-Flame Carbon-Arc Exposures of Paint and Related CoatingsD870 Practice for Testing Water Resistance of Coatings Using Water ImmersionD1005 Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Microm
18、etersD1186 Test Methods for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to a FerrousBase (Withdrawn 2006)3D1654 Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive EnvironmentsD1735 Practice for Testing Water Resistance of Coatings Us
19、ing Water Fog ApparatusD2240 Test Method for Rubber PropertyDurometer HardnessD2244 Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color CoordinatesD2247 Practice for Testing Water Resistance of Coatings in 100 % Relative HumidityD2370 Test Method for
20、 Tensile Properties of Organic CoatingsD3359 Test Methods for Measuring Adhesion by Tape TestD3363 Test Method for Film Hardness by Pencil TestD4145 Test Method for Coating Flexibility of Prepainted SheetD4214 Test Methods for Evaluating the Degree of Chalking of Exterior Paint FilmsD5796 Test Metho
21、d for Measurement of Dry Film Thickness of Thin-Film Coil-Coated Systems by Destructive Means Usinga Boring DeviceG85 Practice for Modified Salt Spray (Fog) Testing3. Terminology3.1 Definitions:3.1.1 SubstrateFor definitions of terms relating to the substrate, see Terminology A902.3.1.2 Coatings:3.1
22、.2.1 acrylic, na polymer based on resins prepared from a combination of acrylic and methacrylic esters, acrylic andmethacrylic acids, and styrene; they contain one or more functional groups such as amide, hydroxy, or carboxy and formthermosetting systems on baking by cross-linking with themselves, o
23、r amino or epoxy resins.3.1.2.2 conversion coating, na chemical treatment, normally applied to a metal surface prior to final finishing, which isdesigned to react with and modify the metal to produce a surface suitable for painting.3.1.2.3 epoxy, npolymers based on epoxy resins, which are the reacti
24、on product of epichlorohydrin and biphenol-A and arecross-linked with amino or urea-formaldehyde resins to form thermosetting systems on baking.3.1.2.4 fluorocarbon, npolymers based on fluorocarbon resins made by the polymerization of vinyl fluoride monomer (PVF)or vinylidene fluoride monomer (PVF2)
25、; these resins are formulated into coatings by dispersion of finely divided particles indispersants and diluents and form thermosetting systems on baking.3.1.2.5 plastisol, na dispersion of finely divided vinyl resin in plasticizers; during the baking process, the resin particles aresolvated by the
26、plasticizer and fuse into a continuous film.3.1.2.6 polyester, na polymer based on the condensation products of polybasic acids and diols (dihydric alcohols), also calledoil-alkyds; they are modified by the addition reaction of monomers such as styrene or acrylic esters; polyester resins arecross-li
27、nked with amino resins to form thermosetting systems on baking.3.1.2.7 polyurethane, na polymer produced by the addition reaction of an acrylic polyol or polyester polyol with anisocyanate-containing compound to produce thermosetting systems on baking.3.1.2.8 primer, nthe first complete layer of pai
28、nt of a coating system applied to an uncoated surface; the type of primer varieswith the type of surface and its condition, the intended purpose, and the coating system being used.3.1.2.9 silicone polyester, na polymer which is the reaction product between an organo-siloxane intermediate and an alky
29、dresin, or a cold blend of a silicone resin and a compatible alkyd resin; these resins are cross-linked with amino resins to formthermosetting systems on baking.3.1.3 Coating Characteristics:3.1.3.1 chalking, vthe formation on a pigmented coating of a friable powder evolved from the film itself at o
30、r just beneaththe surface.3.1.3.2 fade, va loss in color intensity experienced by pigmented organic coatings over time, generally due to the effect ofultraviolet radiation.3 The last approved version of this historical standard is referenced on www.astm.org.A755/A755M 1523.1.3.3 gloss, nthe luster,
31、shininess, or reflecting ability of a surface.3.2 Definitions of Terms Specific to This Standard:3.2.1 bottom side, nthe side of prepainted sheet opposite the exposed weathering side.3.2.2 coil coating, va continuous process by which paint and other coatings are applied and baked onto a moving strip
32、 of steelsheet.3.2.2.1 DiscussionRolls are used to pick up, meter, and deposit the liquid coating onto the moving strip and are also used to support the strip throughthe line. The product of this process is called prepainted steel sheet.3.2.3 mil, na unit of length equal to 0.001 in. 25.4 m, used fo
33、r 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 by baking.3.2.5 roll former, nan apparatus that forms a continuous strip of metal into various shapes by a series of contoured steel rolls.3.2.6
34、top side, nthe side of the prepainted sheet which is exposed to weathering.3.2.7 washcoat, na thin organic coating, usually a polyester, applied to the back or unexposed side of prepainted sheet (alsoknown as a backercoat).3.2.7.1 DiscussionThis pigmented/nonpigmented coating is applied for such rea
35、sons as protection of the topcoat while in coil form, interiorappearance, and lubrication during roll forming.4. Classification4.1 The substrate shall conform to all requirements of the appropriate specification for the steel sheet product ordered as follows:4.1.1 Zinc-Coated (Galvanized)Specificati
36、ons A653/A653M and A1063/A1063M.4.1.2 Zinc-5 % Aluminum Alloy-CoatedSpecification A875/A875M.4.1.3 55 % Aluminum-Zinc Alloy-CoatedSpecification A792/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
37、 metallic-coated sheet specifications describes the range of available coating designations. Theparticular designation selected is related to the expected performance of the exterior exposed building product. Although there areexceptions based on the type of environment where the building is erected
38、, the recommended minimum coating mass designationsfor use in exterior exposed building applications are:Metallic Coating Minimum Recommended CoatingA653/A653M Zinc-Coated (Galvanized) G90 Z275A875/A875M Zinc-5 % Aluminum Alloy-Coated GF75 ZGF225A792/A792M 55 % Aluminum-Zinc Alloy-Coated AZ50 AZM150
39、A463/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 are important to attain the normally expected long-term product life in theapplication. Exceptions to these minim
40、um designations can be considered when the environmental conditions are of low corrosivepotential, such as a very dry climate. In these cases, a lower coating weight mass, for example, G60 Z180 may be appropriate.Similarly, for very corrosive environments, the user should consider specifying a coati
41、ng designation with a heavier coating weightmass.4.2 The organic coating typically consists of a primer and a topcoat 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
42、.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.A755/A755M 1534.2.2.5 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 between the produ
43、cer and the purchaser (see Note 2).5. Ordering Information5.1 The coated flat sheet covered by this specification is produced on continuous lines to decimal thickness only. The thicknessof the sheet includes the base steel and the metallic coating. The thickness of the organic system is in addition
44、to the substrate (basesteel and metallic coating).5.2 Orders for material under this specification shall include the following information, as applicable, to describe the requiredproduct adequately:5.2.1 Product name (prepainted steel sheet),5.2.2 ASTM designation and year of issue, as A755 for inch
45、-pound units or A755M for SI units,5.2.3 ASTM specification number of metallic coated substrate, steel sheet designation, and, if applicable, type (and grade, ifrequired),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 regul
46、ar, minimized spangle, 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 the bottom sidewill consist of a primer and a washcoat, o
47、r the same 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, typeof formed configuration.5.2.11 Coil size requirement: maximum outsid
48、e 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 tolerances for 38-in. 10-mm edge distance (see Supplementary Requirementssection in Specifica
49、tion A924/A924M), this requirement shall 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, ASTM A653/A653M, SS, Grade 40 with G90 coating, extra smooth,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 milthickness, 0.019 in. min thickness by 42 i
