1、Designation: A90/A90M 11A90/A90M 13Standard Test Method forWeight Mass of Coating on Iron and Steel Articles withZinc or Zinc-Alloy Coatings1This standard is issued under the fixed designation A90/A90M; the number immediately following the designation indicates the yearof original adoption or, in th
2、e 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 of the Department of Defense.1. Scope*1.1 This
3、 test method covers procedures for determining the weight mass of coating on iron or steel sheet, wire, and otherarticles in which the coating is zinc or a zinc alloy, such as zinc-5 % aluminum (including zinc-5 % aluminum-mischmetal andzinc-5 % aluminum-0.1 % magnesium), zinc-aluminum-magnesium (in
4、cluding zinc-5 to 9 % aluminum-magnesium and zinc-9 to13 % aluminum-magnesium) or 55 % aluminum-zinc. In the body of this test method, reference to zinc coating shall be interpretedto also include zinc alloy coating except where specifically stated otherwise.1.2 The final results determined by this
5、test method shall be expressed in inch-pound units or SI units, depending on the unitsused in the material specification to which the results are to be compared. Certain portions of the procedure involving determinationof specimen weight mass have traditionally been performed in SI units, and corres
6、ponding inch-pound units are not included.1.3 For sheet products, the final results are expressed as either coating weight mass total both sides, or coating weight massseparately on each side, depending on the specified requirements.1.4 This standard does not purport to address all of the safety con
7、cerns, 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 regulatorylimitations prior to use. For specific hazards statements see 5.1.2. Referenced Documents2.1 ASTM Standards:2
8、A653/A653M Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by theHot-Dip ProcessA792/A792M Specification for Steel Sheet, 55 % Aluminum-Zinc Alloy-Coated by the Hot-Dip ProcessA875/A875M Specification for Steel Sheet, Zinc-5 % Aluminum Alloy-Coated by
9、 the Hot-Dip ProcessA1046/A1046M Specification for Steel Sheet, Zinc-Aluminum-Magnesium Alloy-Coated by the Hot-Dip ProcessA1057/A1057M Specification for Steel, Structural Tubing, Cold Formed, Welded, Carbon, Zinc-Coated (Galvanized) by theHot-Dip ProcessA1063/A1063M Specification for Steel Sheet, T
10、win-Roll Cast, Zinc-Coated (Galvanized) by the Hot-Dip ProcessA1079/A1079M Specification for Steel Sheet, Complex Phase (CP), Dual Phase (DP) and Transformation Induced Plasticity(TRIP), Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip ProcessD1193 Specification for R
11、eagent WaterE29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications3. Significance and Use3.1 This test method provides a standard method for determining the weight mass of coating for comparison with specificationrequirements. A coating of zinc on iron or
12、 steel articles provides protection against corrosion. As the protection is provided by1 This test method is under the jurisdiction of ASTM Committee A05 on Metallic-Coated Iron and Steel Products and is the direct responsibility of Subcommittee A05.07on Methods of Testing.Current edition approved N
13、ov. 1, 2011April 1, 2013. Published November 2011April 2013. Originally approved in 1923. Last previous edition approved in 20092011 asA90/A90M - 09.A90/A90M - 11. DOI: 10.1520/A0090_A0090M-11.10.1520/A0090_A0090M-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM
14、 Customer 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
15、to the 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 Sum
16、mary 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 States1sacrificial loss of zinc, the degree of protection is proportional to the weight mass of zinc coating. Specifications for zinc-
17、coatedarticles frequently provide for different classes of coating so that the purchaser can select the coating weight mass most suitableto his needs.4. Reagents4.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall
18、 conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available.3 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy
19、 of the determination.4.2 Purity of WaterWater used to prepare chemical solutions shall be reagent water as defined by Type IV of SpecificationD1193.4.3 Antimony Trichloride SolutionDissolve 20 g of Sb2O3 or 32 g of SbCl3 in 1000 mL of HCl (sp gr 1.18 to 1.19).4.4 Hydrochloric Acid (sp gr 1.18 to 1.
20、19)Concentrated hydrochloric acid (HCl).4.5 Hydrochloric AcidAntimony Trichloride SolutionAdd 5 mL of antimony trichloride solution to 100 mL of HCl (sp gr1.18 to 1.19).4.6 Hydrochloric Acid (1 + 1)Mix 500 mL of HCl (sp gr 1.18 to 1.19) with 500 mL of reagent water and cool to roomtemperature.4.7 Su
21、lfuric Acid (25 + 75)Mix 250 mL of H2SO4 (sp gr 1.84) with 750 mL of reagent water and cool to room temperature.NOTE 1It is advisable to use an inhibitor with acid solution (for example, Hexamethylamine Tetramine or similar) at the concentration level accordingto the manufacturers recommendations to
22、 prevent attack of the substrate.5. Hazards5.1 WarningSmall amounts of the poisonous gas stibine (SbH3) may be evolved during the stripping process using thehydrochloric acid-antimony trichloride method. Hydrochloric acid fumes are present, and hydrogen gas is evolved in the strippingprocess. Theref
23、ore, the test should be performed under conditions of adequate ventilation. A fume hood is recommended for largenumbers of samples or where the test is to be carried out frequently over extended periods of time.5.2 WarningMixing of sulfuric acid with water could result in severe injuries if not prop
24、erly done. Mixing must be done byslowly adding sulfuric acid to water due to the heat generated and possible splashing. Under no circumstances should the waterbe added to the acid. The mixing should be performed under an acid fume hood.6. Sampling6.1 Zinc-Coated SheetsSamples for weight mass of coat
25、ing determination shall be secured in accordance with SpecificationsA653/A653M, A792/A792M, A875/A875M, A1046/A1046M, A1057/A1057Mor, A1063/A1063M, or A1079/A1079M depend-ing on the type of coating.NOTE 2For convenience in calculating test results in inch-pound units, the specimen should have an are
26、a of 5.08 in.2 of sheet (2.25 6 0.01-in. squareor 2.54 6 0.01 in. in diameter). The weight mass of coating in grams on a specimen of that area is numerically equal to the weight mass of coatingin ounces per square foot of sheet. For results to be reported in metric units, the specimen should have an
27、 area of 3330 mm2 of sheet (57.7 6 0.1-mmsquare or 65.1 6 0.1 mm in diameter).6.2 Zinc-Coated WireSamples shall be secured as designated in the appropriate specification. The specimen of wire may beof any length over 12 in. 305 mm, but preferably about 24 in. 609 mm. Where a continuous length is not
28、 available, shorterlengths totaling over 12 in. 300 mm, but preferably about 24 in. 600 mm, shall be used. Since the density of the steel is known0.283 lb/in.3 7830 kg/m3, it is not necessary to use a specific length of specimen.6.3 Zinc-Coated Articles Other Than Sheet or WireSamples for weight mas
29、s of coating determination shall be secured asdesignated in the appropriate specification. Except as otherwise provided, the specimens should have a minimum area of 3 in.2(2000 mm2) of zinc-coated surface. For very small items, several pieces may have to be stripped to obtain the minimum area.6.3.1
30、In the case of threaded articles, such as bolts and screws, the determination shall be made on a portion of the articles thatdoes not include any thread.7. Procedure7.1 Strip the zinc coating from the specimens by using one of the following methods: hydrochloric acid (1 + 1), hydrochloricacid-antimo
31、ny trichloride solution, or sulfuric acid (25 + 75). For zinc alloy coatings containing less than 90 % zinc, the strippingshall be done using hydrochloric acid (1 + 1) or sulfuric acid (25 + 75).3 “Reagent Chemicals, American Chemical Society Specifications,” Am. Chemical Soc., Washington, DC. For s
32、uggestions on the testing of reagents not listed by theAmerican Chemical Society, see “Analar Standards for Laboratory U.K. Chemicals,” BDH Ltd., Poole, Dorset, and the “United States Pharmacopeia.”A90/A90M 1327.2 Clean the specimens by washing with solvent naphtha or other suitable solvent, then ri
33、nse with alcohol, and dry thoroughly.7.3 Determine the weight mass of the specimens individually to the nearest 0.01 g, except for articles other than sheet or wirewith a specimen weight mass greater than 125 g, determine the weight mass to at least the nearest 0.1 g. After determining theweight mas
34、s, immerse each specimen singly in the stripping solution and allow to remain until the violent evolution of hydrogenhas ceased, and only a few bubbles are being evolved. This requires about 15 to 30 s, except in the case of sherardized coatings,which require a somewhat longer time. The same solutio
35、n may be used repeatedly until the time required for stripping becomesinconveniently long. The temperature of the stripping solution shall at no time exceed 100F 38C. After stripping, wash thespecimens by scrubbing them under running water, dip in hot water, and wipe or blow dry. Determine the weigh
36、t mass of thespecimens again, to the same precision as in the initial determination.7.4 Sheet SpecimensWhen measuring the total coating weight mass on both sides, or the single side coating weight masson each side, determine the area of sheet (one surface) to the nearest 0.01 in.2 5 mm2. If specimen
37、s were prepared to thedimensions as provided in Note 2, they shall be presumed to have an area of 5.08 in.2 3330 mm2. When it is not possible todetermine the area accurately, as in specimens from corrugated sheets, the thickness of the stripped sheet shall be determined tothe nearest 0.001 in. 0.01
38、mm.7.4.1 When determining the coating weight mass on one side of sheet material, use the procedure described in 7.3, except usea “stop-off” to protect one side from the stripping medium. Acid-resistant paints or lacquers, acid-resistant tape, or mechanicaldevices fastened to the test specimen are ex
39、amples of commonly used “stop-off” materials. Apply the “stop-off” to the specimenafter the initial determination of weight mass and remove before the second determination of weight mass. Because of thepossibility of moisture absorption during the stripping process, the “stop-off” must not be on the
40、 specimen during either weightmass determinations. Determine the coating weight mass on the second side subsequently without a “stop-off” on the first side.7.5 Wire SpecimensDetermine the diameter of the stripped wire to the nearest 0.001 in. 0.01 mm by taking the average oftwo measurements at right
41、 angles to each other.7.6 Specimens Other Than Sheet or WireDetermine the total coated area of the original specimen to the nearest 0.01 in.2 5mm2. Alternatively, for specimens of uniform thickness of base metal, such as a piece of plate or pipe, determine the averagethickness of the stripped specim
42、en to the nearest 0.001 in. 0.01 mm.8. Calculation8.1 Zinc-Coated Sheet:8.1.1 Results in Inch-Pound Units:8.1.1.1 When the area of one surface of the sheet is determined, calculate the weight mass of coating as follows:C 5W12W2!/A# 3K (1)where:C = weight mass of coating, oz/ft2 of sheet,W1 = origina
43、l weight mass of specimen, g,W2 = weight mass of stripped specimen, g,A = area of one surface of the sheet, in.2 or mm2, and,K = a constant = 5.08 when A is in in.2, or = 3.28 103 when A is in mm2.NOTE 3If the specimen was prepared to the dimensions as provided in Note 2, having an area of 5.08 in.2
44、, the loss of weight mass in grams isnumerically equal to the weight mass of coating in ounces per square foot of sheet.8.1.1.2 When it is not possible to secure a specimen of measurable area, calculate the weight mass of coating as follows:C 5W12W2!/W2#3T 3K (2)where:C = weight mass of coating, oz/
45、ft2 of sheet,W1 = original weight mass of specimen, g,W2 = weight mass of stripped specimen, g,T = thickness of stripped sheet, in. or mm, andK = a constant = 652 when T is in in., or = 25.7 when T is in mm.8.1.2 Results in Metric Units:8.1.2.1 When the area of sheet is determined, calculate the wei
46、ght mass of coating as follows:C 5W12W2!/A# 3K (3)where:C = weight mass of coating, g/m2 of sheet,W1 = original weight mass of specimen, g,W2 = weight mass of stripped specimen, g,A90/A90M 133A = area of one surface of the sheet, in.2 or mm2, andK = a constant = 1.55 103 when A is in in.2, or = 1 10
47、6 when A is in mm2.NOTE 4If the specimen was prepared to the dimensions as provided in Note 2, having an area of 3330 mm2 of sheet, the factor K/A is approximately300, which may be used in the calculation.8.1.2.2 When it is not possible to obtain a specimen of measurable area, calculate the weight m
48、ass of coating as follows:C 5W12W2!/W2#3T 3K (4)where:C = weight mass of coating, g/m2 of sheetW1 = original weight mass of the specimen, g,W2 = weight mass of the stripped specimen, g,T = thickness of stripped sheet, in. or mm, andK = a constant = 1.99 105 when T is in in., or = 7.83 103 when T is
49、in mm.8.2 Zinc-Coated Wire:8.2.1 Results in Inch-Pound Units:8.2.1.1 Calculate the weight mass of zinc coating as follows:C 5W12W2!/W2#3D 3M (5)where:C = weight mass of coating, oz/ft2 of stripped wire surface,W1 = original weight mass of specimen, g,W2 = weight mass of stripped specimen, g,D = diameter of stripped wire, in. or mm, andM = a constant = 163 when D is in in., or = 6.42 when D is in mm.8.2.2 Results in Metric Un
