ASTM G66-1999(2018) Standard Test Method for Visual Assessment of Exfoliation Corrosion Susceptibility of 5XXX Series Aluminum Alloys (ASSET Test).pdf

1、Designation: G66 99 (Reapproved 2018)Standard Test Method forVisual Assessment of Exfoliation Corrosion Susceptibility of5XXX Series Aluminum Alloys (ASSET Test)1This standard is issued under the fixed designation G66; the number immediately following the designation indicates the year of originalad

2、option or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a procedure for continuousimmersion exfoliatio

3、n corrosion testing of 5XXX seriesaluminum-magnesium alloys containing 2.0 % or more mag-nesium.1.2 This test method applies only to wrought products.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does no

4、t purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international s

5、tandard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2

6、. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterG15 Terminology Relating to Corrosion and Corrosion Test-ing (Withdrawn 2010)32.2 ASTM Adjuncts:ASSET Tested Specimens (Glossy Prints)43. Terminology3.1 Definitions:3.1.1 exfoliationcorrosion that proceeds laterally from

7、thesites of initiation along planes parallel to the surface, generallyat grain boundaries, forming corrosion products that forcemetal away from the body of the material, giving rise to alayered appearance (see Terminology G15).4. Summary of Test Method4.1 Specimens are immersed for 24 h at 65 6 1C (

8、150 62F) in a solution containing ammonium chloride, ammoniumnitrate, ammonium tartrate, and hydrogen peroxide. The sus-ceptibility to exfoliation is determined by visual examinationusing performance ratings established by reference to standardphotographs.5. Significance and Use5.1 This test method

9、provides a reliable prediction of theexfoliation corrosion behavior of Al-Mg alloys in marineenvironments.5,6,7The test is useful for alloy developmentstudies and quality control of mill products such as sheet andplate.6. Apparatus6.1 Any suitable glass or plastic container can be used tocontain the

10、 solution and specimens during the test period.Depending upon the shape and size of the specimens, rods orracks of glass, plastic, or other inert substance shall be used tosupport the specimens above the bottom of the container. Thecontainer should be fitted with a removable cover to reduceevaporati

11、on.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.1This test method is under the jurisdiction of ASTM Committee G01 onCorrosion of Metals and is the direct responsibility of Subcommittee G01.05 onLaboratory Corrosion Tests. This method was developed by a joint tas

12、k group withThe Aluminum Assoc., Inc.Current edition approved Oct. 1, 2018. Published November 2018. Originallyapproved in 1980. Last previous edition approved in 2013 as G66 99 (2013). DOI:10.1520/G0066-99R18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custo

13、mer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from ASTM International Headquarters. Order Adjunct No.A

14、DJG0066. Original adjunct produced in 1987.5Aluminum Association Technical Report T1, “Exfoliation Corrosion Testing ofAluminum Alloys 5086 and 5456”.6Sprowls, D. O., Walsh, J. D. and Shumaker, M. B., “Simplified ExfoliationTesting ofAluminumAlloys”, Localized CorrosionCause of Metal Failure, ASTMST

15、P 516, ASTM, 1972, pp 3865.7Summerson T. J., Interim Report, Aluminum Association Task Group onExfoliation and Stress Corrosion Cracking of Aluminum Alloys for Boat Stock;Proceedings Tri-Service Corrosion Military Equipment Conference, October 2931,1974; Technical Report AFML-TR-75-42, Vol. II, p. 1

16、93221, February 1, 1975.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for

17、 theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.17.2 Purity of WaterDistilled or deionized water conform-ing to Specification D1193. Type IV shall be used to preparethe test solution except chlo

18、ride ion sodium limits can bedisregarded.8. Test Solution8.1 Preparation of Test Solution:8.1.1 The test solution shall have the following composi-tion:NH4Cl (1.0 M)NH4NO3(0.25 M)(NH4)2C4H4O6(0.01 M)H2O2(0.09 M)8.1.2 Dissolve 53.5 g ammonium chloride (NH4Cl), 20.0 gammonium nitrate (NH4NO3), 1.8 g a

19、mmonium tartrate(NH4)2C4H4O6), and 10 mL of 30 % stock solution hydrogenperoxide (H2O2) in a small amount of water. After dissolving,mix the components together thoroughly and adjust the finaldilution to 1 L.NOTE 1If a stock solution of the above chemicals is to be stored, thehydrogen peroxide shoul

20、d not be added until the solution is heated for thetest.8.2 The solution will have a typical pH of 5.2 to 5.4.8.3 The solution shall be used in sufficient quantity toprovide a volume-to-exposed specimen surface area ratio of atleast 100 L/m2(65 mL/in.2).8.4 The temperature of the solution shall be m

21、aintained at65 6 1C (150 6 2F).9. Sampling9.1 The procedure for sampling mill products is covered inproduct specifications, or otherwise, and is considered outsidethe scope of this standard.10. Test Specimen10.1 While this test method can be used with any form ofspecimen or part that can be immersed

22、 in the test solution, it ispreferred that specimens be at least 40 by 100 mm (1.5 by 4.0in.) with the metal working direction in the 40-mm (1.5-in.)dimension.10.2 The specimens should be sawed or machined to mini-mize introducing residual stresses in edges during preparationof the specimens (sheare

23、d edges are allowed only if the edgesare sufficiently dressed or filed down a distance equal to thethickness of the specimen in order to remove metal deformedby shearing).11. Standardization11.1 To provide an indication when some inadvertent de-viation from the correct test conditions occurs, it is

24、necessaryto expose to the test at regular intervals a control specimen ofa material of known susceptibility. This control should exhibitthe same degree of exfoliation each time it is included in thetest.11.2 The control may be any material of the Al-Mg seriesthat has a well-documented susceptibility

25、 to exfoliationcorrosion, preferably one with an intermediate susceptibility.12. Procedure12.1 Degrease the specimens with a suitable solvent. Afterdegreasing, prepare specimens as follows: Etch 1 min in 5 %by weight sodium hydroxide solution at 80C (176F), rinse inwater, desmut 30 s in concentrated

26、 nitric acid at roomtemperature, rinse with distilled or deionized water, air dry.NOTE 2If specimens are not to be immersed in the test solutionimmediately, they should be stored in a desiccator maintained at less than1 % relative humidity (use fresh desiccant such as activated alumina oranhydrous c

27、alcium sulfate).812.2 Use fresh solution at the start of each test.12.3 Immerse the specimens vertically with the top edge ofthe specimens at least 25 mm (1 in.) below the surface of thesolution and the bottom edge at least 25 mm above the bottomof the container.12.4 Immerse the specimens in the tes

28、t solution continu-ously for 24 h.12.5 Rinse the specimens gently in running tap waterimmediately after removal from the solution, then soak inconcentrated nitric acid at room temperature until they appearclean, again rinse in water, and air dry.12.5.1 Air-blast drying is to be avoided in order to p

29、reventmechanical removal of exfoliated metal.13. Rating of Specimens13.1 The following codes and classifications shall be usedfor reporting the visual appearance of corroded specimens.Code ClassificationN No appreciable attackP PittingE Exfoliation13.2 Descriptions of the various classifications, wh

30、ich areillustrated in Figs. 1 and 2,4are as follows:13.2.1 N (no appreciable attack)Surface may be etched ordiscolored.13.2.2 P (Pitting)Includes discrete pitting or pit-blistering. In the latter case, attack results in a slight undercut-ting of the surface. Pitting or pit-blistering is to be expect

31、edand may occur in varying degrees of severity, as shown in Fig.1; it should not be construed as exfoliation.13.2.3 E (Exfoliation)Visible lifting of the surface. Arange of exfoliation can occur in varying degrees of severity, asshown in Fig. 2.13.3 Ratings of different levels of pitting or exfoliat

32、ion maybe indicated PA, PB, PC or EA, EB, EC, ED as shown in Figs.1 and 2.14. Report14.1 Report the following information:14.1.1 Alloy and temper,8Drierite, (a special form of anhydrous calcium sulfate), available from W. A.Hammond Drierite Co., 120 DaytonAve., Xenia, OH 45385, or an equivalent dryi

33、ngagent may be used. If you are aware of alternative suppliers, please provide thisinformation to ASTM International Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee1, whichyou may attend.G66 99 (2018)214.1.2 Product of material tested

34、, including reference toapplicable product specification,14.1.3 Sampling procedure if other than that specified inreferenced product specification,14.1.4 Arating of the test specimens using the code given inSection 13,14.1.5 Notation of any deviation in test procedure from thatset forth in preceding

35、 paragraphs,14.1.6 Size, type, and number of replicate specimens;method of edge preparation, and14.1.7 Solution volume to specimen surface area ratio.15. Precision and Bias15.1 Precision:15.1.1 The precision of the data from this test method wasevaluated by way of an interlaboratory test program usi

36、ng onecommercial and one non-commercial tempers of Alloy 5086with different levels of exfoliation corrosion susceptibility. Sixlaboratories, including experienced and inexperienced users,participated in the round-robin. The laboratories receivedduplicate rough cut panels of each material which theyp

37、repared, exposed, and rated visually according to this testmethod.15.1.2 Raw data from the laboratories are listed in Table 1and plotted as a histogram in Fig. 3. All six laboratories easilydifferentiated between the two materials finding one resistantand one susceptible to exfoliation corrosion.FIG

38、. 1 ASSET Tested Exfoliation Resistant Specimens (NNo appreciable attack; A, B, CThree Degrees of Pittingand Pit-Blistering)FIG. 2 ASSET Tested Exfoliation Susceptible Specimens (A, B, C, DFour Degrees of Exfoliation)G66 99 (2018)315.1.2.1 The data in Table 1 show the ratings were repeat-able within

39、 laboratories. In each case the same rating wasobtained for both panels tested by the individual laboratory.15.1.2.2 The reproducibility of ratings among differentlaboratories was consistent for the resistant material with alllaboratories obtaining pitting ratings. In the case of theexfoliation susc

40、eptible material the ratings between laborato-ries were within one rating category.15.2 Bias:15.2.1 The procedure in Test Method G66 has no biasbecause the exfoliation rating is defined only in terms of thistest method.16. Keywords16.1 aluminum alloys; 5XXX aluminum alloys; exfoliationcorrosion; pit

41、ting corrosion; visual inspectionASTM 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 advised that determination of the validity of any such patent rights, and the riskof

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46、8) 646-2600; http:/ 1 ASSET (Test Method G66) Round Robin ResultsLaboratoryNo.MaterialExfoliationTypeVolume/Area(L/m2)MachinedSpecimens/ContainerVisualRatings1 Resistant 100 Yes 2 PA1 Resistant 100 Yes 2 PA1 Susceptible 100 Yes 2 EC1 Susceptible 100 Yes 2 EC2 Resistant 83 No 1 PA2 Resistant 83 No 1

47、PA2 Susceptible 83 No 1 EC2 Susceptible 83 No 1 EC3 Resistant 118 Yes 2 PA3 Resistant 118 Yes 2 PA3 Susceptible 118 Yes 2 EC3 Susceptible 118 Yes 2 EC4 Resistant 159 No 1 PA4 Resistant 159 No 1 PA4 Susceptible 159 No 1 ED4 Susceptible 159 No 1 ED5 Resistant 115 No 1 PA5 Resistant 115 No 1 PA5 Susceptible 115 No 1 EC5 Susceptible 115 No 1 EC6 Resistant 211 No 4 PB6 Resistant 211 No 4 PB6 Susceptible 211 No 4 ED6 Susceptible 211 No 4 EDFIG. 3 Histogram of Visual Exfoliation Ratings by Six Laborato-ries for Two Tempers of 5086 Plate Tested by ASSET (Data inTable 1)G66 99 (2018)4