1、Designation: D 522 93a (Reapproved 2008)Standard Test Methods forMandrel Bend Test of Attached Organic Coatings1This standard is issued under the fixed designation D 522; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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. Scope1.1 These test methods cover the determi
3、nation of theresistance to cracking (flexibility) of attached organic coatingson substrates of sheet metal or rubber-type materials.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to addre
4、ss 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 prior to use.2. Referenced Documents2.1 ASTM Standards:2D 823 Practices
5、 for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD 1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD 1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Fe
6、rrous Base3D 1400 Test Method for Nondestructive Measurement ofDry Film Thickness of Nonconductive CoatingsApplied toa Nonferrous Metal Base33. 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
7、 curing the coated panels are bent over amandrel and the resistance to cracking of the 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 Coating
8、s attached to substrates are elongated when thesubstrates are bent during the manufacture of articles or whenthe articles are abused in service. These test methods have beenuseful in rating attached coatings for their ability to resistcracking when elongated. They have been useful in evaluatingthe f
9、lexibility of coatings on flexible substrates.5. Test Specimen5.1 Substrates:5.1.1 If the purpose of the test is to determine the percent ofelongation of the coating material, 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 t
10、he coated materialfor resistance to cracking, the substrate may be any type ofsheet metal or rubber-type material (for example, steel, alumi-num, tinplate, or synthetic rubber). The thickness of the sheetmetal may be less than 0.8 mm (132 in.) and the thickness of therubber-type materials may be as
11、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 in.) wideand 190 mm (712 in.) long.5.1.4 The surface preparation of the substrate shall beagreed upon between the p
12、urchaser and the seller. Prior to theapplication 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 m
13、ust bemeasured with 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 D 823 and air dry orbake under conditions mutually agreeable to the purchaser andthe seller. If percent elo
14、ngation is to be measured, a minimumthickness of 1.0 mil is required on 0.8 mm (132 in.) thick1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.23 on Physical Properties
15、of Applied PaintFilms.Current edition approved Feb. 15, 2008. Published February 2008. Originallyapproved in 1939. Last previous edition approved in 2001 as D 522 93a (2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For
16、Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Copyright by ASTM Intl (all rights reserved); Thu Mar 13 22:3
17、2:46 EST 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.cold-rolled steel. Perform a minimum of three determinationsof coating thickness on each of the specimens in accordancewith Test Methods D 1005, D 1186,orD 1400.5.2.2 From precoated
18、sheets cut at least three specimens ofthe size 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 c
19、racking. Measure the film thickness as in 5.2.1.6. Conditioning and Number of Tests6.1 Condition the test specimens for at least 24 h 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 purchase
20、r and seller.6.2 Test at least three replicate 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 pa
21、nel clamps, all mounted ona metal base as illustrated in Fig. 1.7.1.1 Cone, smooth steel, 8 in. (200 mm) in length, with adiameter of 3 mm (18 in.) at one end and a diameter of 38 mm(112 in.) at the other end.8. Procedure8.1 With the operating lever of the apparatus in a horizontalposition, slip the
22、 test specimen between the mandrel and thedrawbar with 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 t
23、wo sheets of No. 1 brown kraft wrappingpaper, substrate 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 approxi
24、mately 135. If the purpose of thetest is to measure elongation, the bend should be 15 s. Todetermine crack resistance under more simulated use condi-tions, the bend time should be about 1 s unless an alternativetime is agreed upon between the producer and the user.8.3 Examine the bent surface of the
25、 specimen immediatelywith the unaided eye 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 distanc
26、e from the farthest endof the crack to 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. Calculat
27、ion9.1 When required, determine the elongation 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 1.0 mil coating thickness. Therelation between the distance along the conical mandrel and th
28、ecorresponding diameter has also been plotted on this curve.9.2 Adjust the percent elongation value obtained from Fig.2 for coating thickness 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
29、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 determine the percentelongation of the film from the measured crack distance, in this example5.2 %. To correct for coating thickness add the value obtained in Fi
30、g. 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 m(2 mils), the actual percent elongation is 5.2 + (2 3 0.3) = 5.8 %.10. Report10.1 Report the following information:10.1.1 Mean and range of coating elong
31、ation or resistance tocracking values for each specimen,FIG. 1 Conical Mandrel Test ApparatusFIG. 2 Distance Along Cone and Corresponding Mandrel Sizeversus Percent Elongation for Specimens on Cold-Rolled Steel0.8mm(132 in.) in ThicknessD 522 93a (2008)2Copyright by ASTM Intl (all rights reserved);
32、Thu Mar 13 22:32:46 EST 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.10.1.2 Mean and range of coating film thickness for eachspecimen,10.1.3 Specimen preparation procedures used,10.1.4 Test conditions, and10.1.5 Mean and range of elonga
33、tion or resistance to crack-ing, and film thickness for the replicate specimens.11. Precision and Bias411.1 PrecisionOn the basis of an interlaboratory test oflimited scope4in which two coatings differing in their flexibil-ity were tested at two different times by operators in threelaboratories, the
34、 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 should be used for at the 95 %confidence level judging the acceptability of results:11.1.1 Repe
35、atabilityTwo 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 each the meanof duplicates obtained by operators in different laboratoriesshould be considered
36、 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 flexibility, bias cannot be determined.TEST METHOD BCYLINDRICAL MANDREL TEST12. Apparatus12.1 El
37、ongation 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 base.An exampleof an acceptable form of this device is illustrated in Fig. 4.13. P
38、rocedure13.1 Place the test panel over a mandrel with the uncoatedside in contact and with at least 2 in. (50 mm) overhang oneither side. Using a steady pressure of the fingers, bend thepanel approximately 180 around the mandrel at a uniformvelocity in a time of 1 s unless an alternative time is agr
39、eedupon between the producer and the user. Remove and examinethe panel immediately for cracking visible to the unaided eye.If cracking has not occurred, repeat the procedure usingsuccessively smaller diameter mandrels on previously untestedareas of a specimen until failure occurs or until the smalle
40、stdiameter 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 takenas the mandrel diameter at which cracking ceases.13.2 To determine elongation
41、 of the applied coating, followthe procedure given in 13.1, using a bend time of 15 s.14. Calculation14.1 Determine the elongation range of the material fromTable 1 in which the elongation of a 25 m (1 mil) thickcoating on 0.8 mm (132 in.) cold-rolled steel is given for eachmandrel diameter.4Support
42、ing data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D011069.FIG. 3 Correction for Thickness of FilmFIG. 4 An Illustration of a Cylindrical Mandrel Test ApparatusD 522 93a (2008)3Copyright by ASTM Intl (all rights reserved); Thu Mar 13 22:32
43、:46 EST 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.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 tota
44、lelongation of the coating as follows:E 5 e11 tc1where:E = total elongation, %,e1= elongation from Table 1,%,t = thickness, 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
45、 specimen,15.1.2 Mean and range of coating thickness for each speci-men,15.1.3 Specimen preparation procedures used,15.1.4 Test conditions, and15.1.5 Mean and range of elongation, resistance to cracking,and film thickness for the replicate specimens.16. Precision and Bias16.1 Results are not availab
46、le to determine the precision 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 BET
47、WEEN ELONGATION AND MANDREL 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 limi
48、ts of the specimens are not exceeded.X1.2 The elongation values corresponding to mandreldiameters in Fig. 2 and Fig. 3 of these test methods wereobtained by direct measurements with a special mandrel jig.ASTM International takes no position respecting the validity of any patent rights asserted in co
49、nnection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Interna
