1、Designation: D522/D522M 13Standard 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD1005 Test Method for M
6、easurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic, Nonconductive Coat-ings Applied to Non-Ferrous Metals3. Summary of Test Method3.1 The coating ma
7、terials 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 the coating isdetermined. In Test Method A the coated panels are bent overa conical mandrel. In Test
8、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 bent during the manufacture of articles or whenthe articles are abused in service. These test methods have beenuseful in r
9、ating attached coatings for their ability to resistcracking when elongated. They have been useful in evaluatingthe 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 subs
10、trate 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 rubber). The thickn
11、ess 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 in. wideand 1
12、90 mm 712 in. long.5.1.4 The surface preparation of the substrate shall beagreed upon between the 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 deter
13、mined for coatings applied tosubstrates other than 0.8 mm 132 in. thick cold-rolled steel, they 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 D823 and a
14、ir dry orbake under conditions mutually agreeable to the purchaser andthe seller. If percent elongation is to be measured, a minimumthickness of 25.4 m 1.0 mil is required on 0.8 mm 132 in.1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, a
15、nd Applications and are the directresponsibility of Subcommittee D01.23 on Physical Properties of Applied PaintFilms.Current edition approved Nov. 1, 2013. Published December 2013. Originallyapproved in 1939. Last previous edition approved in 2008 as D522 93a (2008).DOI: 10.1520/D0522_D0522M-13.2For
16、 referenced ASTM standards, visit the ASTM website, 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,
17、 West Conshohocken, PA 19428-2959. United States1thick 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 given in 5.1.3. Use onl
18、y 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 5.2.1.6. Conditioning and Nu
19、mber 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 replicate specimens in Test Meth
20、od 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 illustrated in Fig. 1.7.1.1
21、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 with the finish side towar
22、ds 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, substrate 30, thoroughly lubri
23、cated 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 elongation, the bend tim
24、e 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 eye for cracking. Having
25、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 the small end of the man
26、drel. 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 elongation of the finishfro
27、m 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.The relation between the distance along the conical mandreland the corresponding diameter has also been plotted on thiscur
28、ve.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 thickness shows thatthe end of the first crack in the coati
29、ng 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 Fig. 3.Ata crack distance of 75 mm 3 in. the correction per 25
30、m 1 mil ofcoating thickness is 0.3 %. If the film thickness in the example is 50 m2 mils, the actual percent elongation is 5.2 + (2 0.3) = 5.8 %.10. Report10.1 Report the following information:FIG. 1 Conical Mandrel Test ApparatusFIG. 2 Distance Along Cone and Corresponding Mandrel Sizeversus Percen
31、t Elongation for Specimens on Cold-Rolled Steel0.8mm132 in. in ThicknessD522/D522M 13210.1.1 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 procedures used,10.1.4 Test
32、 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 in their flexibil-ity we
33、re 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 should be used for at th
34、e 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 each the meanof duplica
35、tes 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 flexibility, bias cannot
36、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 base.An exampleof an acc
37、eptable form of this device is illustrated in Fig. 4.13. 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 at a uniformvel
38、ocity 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 previouslyuntested
39、 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 takenas the mandrel
40、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.3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D01-1069.FIG. 3 Correction
41、 for Thickness of FilmFIG. 4 An Illustration of a Cylindrical Mandrel Test ApparatusD522/D522M 13314. 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.
42、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 e11tc1where:E = total elongation, %,e1= elongation from Table 1,%,t = thickne
43、ss, 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 thickness for eachspecimen,15.1.3 Specimen preparation procedures used,15.1
44、.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 precision ofthese test methods. These test methods have been in use forman
45、y 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 MANDREL SIZEX1.1 In the mandrel test, the specimens are elongatedconsidera
46、bly 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-am
47、eters in Fig. 2 and Fig. 3 of these test methods were obtainedby direct measurements with a special mandrel jig.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advis
48、ed 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 r
49、eapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrig
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