1、Designation: D 522 93a (Reapproved 2001)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:D 823 Practices
5、for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test Panels2D 1005 Test Methods for Measurement of Dry-Film Thick-ness of Organic Coatings Using Micrometers2D 1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa
6、Ferrous Base2D 1400 Test Method for Nondestructive Measurement ofDry Film Thickness of Nonconductive Coatings Applied toa Nonferrous Metal Base23. 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
7、 or 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 Coat
8、ings 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 evaluatingth
9、e flexibility 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 rat
10、e the 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
11、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 in.) wideand 190 mm (712 in.) long.5.1.4 The surface preparation of the substrate shall beagreed upon between th
12、e purchaser 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, the
13、y must 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
14、elongation is to be measured, a minimumthickness of 1.0 mil is required on 0.8 mm (132 in.) thickcold-rolled steel. Perform a minimum of three determinationsof coating thickness on each of the specimens in accordancewith Test Methods D 1005, D 1186, or D 1400.5.2.2 From precoated sheets cut at least
15、 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 cracking. Measure th
16、e film thickness as in 5.2.1.1These test methods are under the jurisdiction of ASTM Committee D-1 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved Sept. 15, 1993. Pu
17、blished November 1993. Originallypublished as D 522 39. Last previous edition D 522 93.2Annual Book of ASTM Standards, Vol 06.01.1Copyright ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.6. Conditioning and Number of Tests6.1 Condition the test specimens for at least 24
18、 h at 23 62C ( 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 replicate specimens in Test Method Aand at least two replicate specimens in Test Method B at e
19、achmandrel 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 illustrated in Fig. 1.7.1.1 Cone, smooth steel, 8 in. (200 mm) in length, with adiameter
20、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 test specimen between the mandrel and thedrawbar with the finish side towards the drawbar. Rigidlyclamp the specimen in a vertical
21、 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, substrate 30, thoroughly lubricated on each side withtalc, between the specimen and t
22、he 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 elongation, the bend should be 15 s. Todetermine crack resistance under more si
23、mulated 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 specimen immediatelywith the unaided eye for cracking. Having determined andsuitably marked the end of the crack farthest from the
24、 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 the small end of the mandrel. This distance isused to compute the elongation. The mandrel di
25、ameter 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 elongation of the finishfrom the plotted curve in Fig. 2. This curve represents therelationship
26、 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 thecorresponding diameter has also been plotted on this curve.9.2 Adjust the percent elongation value obtained from Fig.2 for coating
27、 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 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
28、 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 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 th
29、e 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 elongation or resistance tocracking values for each specimen,10.1.2 Mean and range of coating film thickness for eachspecimen,10.1.3 Sp
30、ecimen preparation procedures used,10.1.4 Test conditions, and10.1.5 Mean and range of elongation or resistance to crack-ing, and film thickness for the replicate specimens.FIG. 1 Conical Mandrel Test ApparatusFIG. 2 Distance Along Cone and Corresponding Mandrel Sizeversus Percent Elongation for Spe
31、cimens on Cold-Rolled Steel0.8 mm (132 in.) in ThicknessD 522211. Precision and Bias311.1 PrecisionOn the basis of an interlaboratory test oflimited scope3in which two coatings differing in their flexibil-ity were tested at two different times by operators in threelaboratories, the intralaboratory s
32、tandard 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 RepeatabilityTwo deter
33、minations 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 to be suspect if
34、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 MANDRELTEST12. Apparatus12.1 Elongation Test Equip
35、ment, 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. Procedure13.1 Plac
36、e 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 agreedupon between t
37、he 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 smallestdiameter mandre
38、l 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 of the applied c
39、oating, 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.14.2 If the coating thick
40、ness 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:3Supporting data are available from ASTM Headquarters. Request RR:D011069.FIG. 3 Correction for Thicknes
41、s of FilmFIG. 4 An Illustration of a Cylindrical Mandrel Test ApparatusD 5223E 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
42、or resistance tocracking values for each 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. Precis
43、ion and Bias16.1 Results are not available 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(Nonma
44、ndatory Information)X1. RELATIONSHIP BETWEEN 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
45、on the assump-tion that the elastic limits 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.The American Society for Testing and Materials takes no
46、position respecting the validity of any patent rights asserted in connectionwith any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any suchpatent rights, and the risk of infringement of such rights, are entirely their own responsi
47、bility.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
48、 ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsibletechnical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make yourviews known to the ASTM Committee on Standards, at the address shown belo
49、w.This standard is copyrighted by ASTM, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above address or at610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website (www.astm.org).TABLE 1 ElongationMandrel Diameter, in. (mm) Elongation,%1 (25) 3.334 (19) 4.412 (12.7) 6.7538 (9.5) 9.014 (6.4) 14.018 (3.2) 28.0TABLE 2 Correction for Film ThicknessMandrel Diamete
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