1、Designation: D522/D522M 17Standard Test Methods forMandrel Bend Test of Attached Organic Coatings1This standard is issued under the fixed designation D522/D522M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revi
2、sion. 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 U.S. Department of Defense.1. Scope1.1 These test methods cover the determinatio
3、n of theresistance to cracking (flexibility) of attached organic coatingson substrates of sheet metal or rubber-type materials.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefor
4、e, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.3 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 t
5、o establish appro-priate safety, health and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Princ
6、iples for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products
7、 on Test PanelsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD2370 Test Method for Tensile Properties of Organic Coat-ingsD7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagneti
8、c, Nonconductive Coat-ings Applied to Non-Ferrous Metals3. Summary of Test Method3.1 The coating materials under test are applied at uniformthickness to panels of sheet metal or rubber-type materials.After drying or curing the coated panels are bent over amandrel and the resistance to cracking of th
9、e coating isdetermined. In Test Method A the coated panels are bent overa conical mandrel. In Test Method B the coated panels are bentover cylindrical mandrels of various diameters.4. Significance and Use4.1 Coatings attached to substrates are elongated when thesubstrates are dimensionally unstable,
10、 or are bent during themanufacture of articles or when the articles are abused inservice. These test methods have been useful in rating attachedcoatings for their ability to resist cracking when elongated.They have been useful in evaluating the flexibility of coatingson flexible substrates. The elon
11、gation of coating films may alsobe tested using Test Method D2370. The correlation betweenelongation determined in accordance with Test Methods D522/D522M and D2370 is unknown.5. Test Specimen5.1 Substrates:5.1.1 If the purpose of the test is to determine the percent ofelongation of the coating mate
12、rial, the substrate shall becold-rolled steel strip 0.8 mm 132 in. (22 gage) thick.5.1.2 If the purpose of the test is to rate the coated materialfor resistance to cracking, the substrate may be any type ofsheet metal or rubber-type material (for example, steel,aluminum, tinplate, or synthetic rubbe
13、r). The thickness of thesheet metal may be less than 0.8 mm 132 in. and the thicknessof the rubber-type materials may be as great as 13 mm 12 in.5.1.3 The recommended panel size is 100 mm 4 in. inwidth and 150 mm 6 in. in length. The maximum size that theconical mandrel can accommodate is 115 mm 412
14、 in. wideand 190 mm 712 in. long.5.1.4 The surface preparation of the substrate shall beagreed upon between the purchaser and the seller. Prior to the1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directrespo
15、nsibility of Subcommittee D01.23 on Physical Properties of Applied PaintFilms.Current edition approved July 1, 2017. Published September 2017. Originallyapproved in 1939. Last previous edition approved in 2013 as D522 13. DOI:10.1520/D0522_D0522M-17.2For referenced ASTM standards, visit the ASTM web
16、site, 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United Stat
17、esThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Tra
18、de (TBT) Committee.1application of the coating, round slightly the edges of metalpanels to remove burrs in order to eliminate anomalous edgeeffects.NOTE 1If elongations are to be determined for coatings applied tosubstrates other than 0.8 mm 132 in. thick cold-rolled steel, they must bemeasured with
19、 a special mandrel jig as described in Appendix X1.2.5.2 Coated Panels:5.2.1 Apply uniform coatings of the materials under test tothe substrates in accordance with Practices D823 and air dry orbake under conditions mutually agreeable to the purchaser andthe seller. If percent elongation is to be mea
20、sured, a minimumthickness of 25.4 m 1.0 mil is required on 0.8 mm 132 in.thick cold-rolled steel. Perform a minimum of three determi-nations of coating thickness on each of the specimens inaccordance with Test Methods D1005 or D7091.5.2.2 From precoated sheets cut at least three specimens ofthe size
21、 given in 5.1.3. Use only plane (flat) sheets and roundthe edges of the panels slightly as in 5.1.4. The coating surfaceshall be free of oil and other foreign matter that might increasethe flexibility of the coating or interfere with the observationfor cracking. Measure the film thickness as in 5.2.
22、1.6. Conditioning and Number of Tests6.1 Condition the test specimens for at least 24 hours at 236 2C 73.5 6 3.5F and 50 6 5 % relative humidity, and testin the same environment or immediately on removal therefromunless otherwise specified by the purchaser and seller.6.2 Test at least three replicat
23、e specimens in Test Method Aand at least two replicate specimens in Test Method B at eachmandrel diameter of interest.TEST METHOD ACONICAL MANDREL TEST7. Apparatus7.1 Conical Mandrel Tester, consisting of a metal cone, arotating panel-bending arm, and panel clamps, all mounted ona metal base as illu
24、strated in Fig. 1.7.1.1 Cone, smooth steel, 200 mm 8 in. in length, with adiameter of 3 mm 18 in. at one end and a diameter of 38 mm112 in. at the other end.8. Procedure8.1 With the operating lever of the apparatus in a horizontalposition, slip the test specimen between the mandrel and thedrawbar wi
25、th the finish side towards the drawbar. Rigidlyclamp the specimen in a vertical position adjacent to themandrel by placing the long edge behind the clamping bar insuch a manner that the panel is always set up to the narrow endof the mandrel. Slip two sheets of No. 1 brown Kraft wrappingpaper, substr
26、ate 30, thoroughly lubricated on each side withtalc, between the specimen and the drawbar and hold inposition only by the pressure of the drawbar against the paper.8.2 Move the lever through about 180 at uniform velocityto bend the specimen approximately 135. If the purpose of thetest is to measure
27、elongation, the bend time should be 15seconds. To determine crack resistance under more simulateduse conditions, the bend time should be about 1 second unlessan alternative time is agreed upon between the producer andthe user.8.3 Examine the bent surface of the specimen immediatelywith the unaided e
28、ye for cracking. Having determined andsuitably marked the end of the crack farthest from the smallend of the mandrel, which shall be considered as the end point,bring the drawbar to the starting position and remove the panelfrom the mandrel. Measure the distance from the farthest endof the crack to
29、the small end of the mandrel. This distance isused to compute the elongation. The mandrel diameter atwhich cracking ceased is taken as the resistance to crackingvalue.NOTE 2In some cases, the measured distance is used as a measure ofcrack resistance.9. Calculation9.1 When required, determine the elo
30、ngation of the finishfrom the plotted curve in Fig. 2. This curve represents therelationship between the percent elongation and the diameter ofthe conical mandrel for a 25.4 m 1.0 mil coating thickness.FIG. 1 Conical Mandrel Test ApparatusFIG. 2 Distance Along Cone and Corresponding Mandrel Sizevers
31、us Percent Elongation for Specimens on Cold-Rolled Steel0.8mm132 in. in ThicknessD522/D522M 172The relation between the distance along the conical mandreland the corresponding diameter has also been plotted on thiscurve.9.2 Adjust the percent elongation value obtained from Fig.2 for coating thicknes
32、s by adding the correction obtained fromFig. 3.NOTE 3ExampleSuppose visual examination of the finish on thebent cold-rolled steel specimens 0.8 mm 132 in. in thickness shows thatthe end of the first crack in the coating is at a distance of 75 mm 3 in.from the small end of the cone. From Fig. 2 deter
33、mine the percentelongation of the film from the measured crack distance, in this example5.2 %. To correct for coating thickness add the value obtained in Fig. 3.Ata crack distance of 75 mm 3 in. the correction per 25 m 1 mil ofcoating thickness is 0.3 %. If the film thickness in the example is 50 m2
34、 mils, the actual percent elongation is 5.2 + (2 0.3) = 5.8 %.10. Report10.1 Report the following information:10.1.1 Mean and range of coating elongation or resistance tocracking values for each specimen,10.1.2 Mean and range of coating film thickness for eachspecimen,10.1.3 Specimen preparation pro
35、cedures used,10.1.4 Test conditions,10.1.5 Mean and range of elongation or resistance tocracking, and film thickness for the replicate specimens, and10.1.6 Substrate material.11. Precision and Bias311.1 PrecisionOn the basis of an interlaboratory test oflimited scope3in which two coatings differing
36、in their flexibil-ity were tested at two different times by operators in threelaboratories, the intralaboratory standard deviation was foundto be 1.5 % elongation, and the interlaboratory standard devia-tion was found to be 4.0 % elongation. Based on these standarddeviations, the following criteria
37、should be used for at the 95 %confidence level judging the acceptability of results:11.1.1 RepeatabilityTwo determinations each the mean ofduplicates obtained by a single operator should be consideredto be suspect if they differ by more than 6 % in elongation.11.1.2 ReproducibilityTwo determinations
38、 each the meanof duplicates obtained by operators in different laboratoriesshould be considered to be suspect if they differ by more than15 % in elongation.11.1.3 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure in these testmethods for measuring f
39、lexibility, bias cannot be determined.TEST METHOD BCYLINDRICAL MANDREL TEST12. Apparatus12.1 Elongation Test Equipment, consisting of rods orsurfaces, including cylindrical steel diameters of 25 mm 1 in,19 mm 34 in., 12.7 mm 12 in., 9.5 mm 38 in., 6.4 mm 14in., and 3.2 mm 18 in., mounted on a metal
40、base.An exampleof an acceptable form of this device is illustrated in Fig. 4.3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D01-1069. ContactASTM CustomerService at serviceastm.org.FIG. 3 Correction for Thickness of FilmFIG. 4
41、An Illustration of a Cylindrical Mandrel Test ApparatusD522/D522M 17313. Procedure13.1 Place the test panel over a mandrel with the uncoatedside in contact and with at least 50 mm 2 in. overhang oneither side. Using a steady pressure of the fingers, bend thepanel approximately 180 around the mandrel
42、 at a uniformvelocity in a time of 1 second unless an alternative time isagreed upon between the producer and the user. Remove andexamine the panel immediately for cracking visible to theunaided eye. If cracking has not occurred, repeat the procedureusing successively smaller diameter mandrels on pr
43、eviouslyuntested areas of a specimen until failure occurs or until thesmallest diameter mandrel has been used.13.1.1 This procedure can be applied as a “pass/fail” test bydetermining whether cracking is produced by a specifiedmandrel size.13.1.2 The resistance to cracking value for a coating is take
44、nas the mandrel diameter at which cracking ceases.13.2 To determine elongation of the applied coating, followthe procedure given in 13.1, using a bend time of 15 seconds.14. Calculation14.1 Determine the elongation range of the material fromTable 1 in which the elongation of a 25 m 1 mil thickcoatin
45、g on 0.8 mm 132 in. cold-rolled steel is given for eachmandrel diameter.14.2 If the coating thickness exceeds 25 m 1 mil, correctthe determined elongation for film thickness using the factorsfor each mandrel diameter given in Table 2. Calculate the totalelongation of the coating as follows:E 5 e11tc
46、1where:E = total elongation, %,e1= elongation from Table 1,%,t = thickness, m mils, andc1= correction factor from Table 2.15. Report15.1 Report the following information:15.1.1 Mean and range of coating elongation or resistance tocracking values for each specimen,15.1.2 Mean and range of coating thi
47、ckness for eachspecimen,15.1.3 Specimen preparation procedures used,15.1.4 Test conditions,15.1.5 Mean and range of elongation, resistance to cracking,and film thickness for the replicate specimens, and15.1.6 Substrate material.16. Precision and Bias16.1 Results are not available to determine the pr
48、ecision ofthese test methods. These test methods have been in use formany years and are considered acceptable for evaluating thecrack resistance of attached coatings.17. Keywords17.1 cracking; flexibility; resistancecrackingAPPENDIX(Nonmandatory Information)X1. RELATIONSHIP BETWEEN ELONGATION AND MA
49、NDREL SIZEX1.1 In the mandrel test, the specimens are elongatedconsiderably past their elastic limit. Therefore, the elongationsobtained are considerably higher than elongation values calcu-lated from a theoretical equation that is based on the assump-tion that the elastic limits of the specimens are not exceeded.X1.2 The elongation values corresponding to mandrel di-ameters in Fig. 2 and Fig. 3 of these test methods were obtainedby direct measurements with a special mandrel
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