ASTM G116-1999(2004) Standard Practice for Conducting Wire-on-Bolt Test for Atmospheric Galvanic Corrosion《大气电流腐蚀用绕线螺栓试验》.pdf

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1、Designation: G 116 99 (Reapproved 2004)Standard Practice forConducting Wire-on-Bolt Test for Atmospheric GalvanicCorrosion1This standard is issued under the fixed designation G 116; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t

2、he year of 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.1. Scope1.1 This practice covers the evaluation of atmosphericgalvanic corrosion of any anodic material that can be ma

3、de intoa wire when in contact with a cathodic material that can bemade into a threaded rod.1.2 When certain materials are used for the anode andcathode, this practice has been used to rate the corrosivity ofatmospheres.1.3 The wire-on-bolt test was first described in 1955 (1),2and has since been use

4、d extensively with standard materials todetermine corrosivity of atmospheres under the names CLI-MAT Test (CLassify Industrial and Marine ATmospheres) (2-5)and ATCORR (ATmospheric CORRosivity) (6-9).1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its

5、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:3G 1 Practice for Preparing, Cleaning, and Evaluating Cor-rosion Test Spec

6、imensG 3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG 15 Terminology Relating to Corrosion and CorrosionTestingG 16 Guide for Applying Statistics to Analysis of CorrosionDataG 50 Practice for Conducting Atmospheric Corrosion Testson MetalsG 82 Guide for De

7、velopment and Use of a Galvanic Seriesfor Predicting Galvanic Corrosion PerformanceG 84 Practice for Measurement of Time-of-Wetness onSurfaces Exposed to Wetting Conditions as in AtmosphericCorrosion TestingG 91 Practice for Monitoring Atmospheric SO2Using theSulfation Plate TechniqueG 92 Practice f

8、or Characterization of Atmospheric TestSitesG 104 Test Method for Assessing Galvanic CorrosionCaused by the Atmosphere43. Terminology3.1 For definitions of terms used in this practice, refer toTerminology G 15. For conventions related to this method,refer to Practice G 3.4. Summary of Practice4.1 Th

9、e practice consists of wrapping a wire of the anodematerial around the threads of a bolt or threaded rod of thecathode material, exposing the assembly to atmosphere, anddetermining mass loss of the anode wire after exposure.Reference specimens of the anode wire on a threaded, non-conductive, non-por

10、ous rod5are used to separate general andcrevice corrosion effects from galvanic corrosion effects.5. Significance and Use5.1 The small size of the wire compared to the shortgalvanic interaction distance in atmospheric exposures gives alarge cathode-to-anode area ratio which accelerates the gal-vanic

11、 attack. The area between the wire and the threads createsa long, tight crevice, also accelerating the corrosion. For thesereasons, this practice, with a typical exposure period of 90days, is the most rapid atmospheric galvanic corrosion test,particularly compared to Test Method G 104. The short dur

12、a-tion of this test means that seasonal atmospheric variability canbe evaluated. (If average performance over a 1-year period isdesired, several staggered exposures are required with this1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibi

13、lity of Subcommittee G01.04 on AtmosphericCorrosion.Current edition approved Nov 1, 2004. Published November 2004. Originallyapproved in 1993. Last previous edition approved in 1999 as G 116 99.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3For refer

14、enced 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.4Withdrawn.5Nylon 66 has been found suitable for this purpose.1Copyrigh

15、t ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.technique.) Reproducibility of this practice is somewhat betterthan other atmospheric galvanic corrosion tests.5.2 The major disadvantage of this test is that the anodematerial must be available

16、 in wire form and the cathodicmaterial must be available in the form of a threaded rod. Thisshould be compared to Test Method G 104 where plate or sheetmaterial is used exclusively.5.3 An additional limitation is that the more anodic materialof the pair must be known beforehand (from information suc

17、has in Guide G 82) or assemblies must be made with thematerial combinations reversed.5.4 The morphology of the corrosion attack or its effect onmechanical properties of the base materials cannot be assessedby this practice. Test Method G 104 is preferable for thispurpose.5.5 This test has been used

18、under the names CLIMAT andATCORR to determine atmospheric corrosivity by exposingidentical specimens made from 1100 aluminum (UNS A91100)wire wrapped around threaded rods of nylon, 1010 mild steel(UNS G10100 or G10080), and CA110 copper (UNS C11000).Atmospheric corrosivity is a function of the mater

19、ial that iscorroding, however. The relative corrosivity of atmospherescould be quite different if a different combination of materialsis chosen.6. Interferences6.1 The manufacturing process used to make the wire androd may affect their corrosion potentials and polarizationbehavior. Material in these

20、 forms may not behave galvanicallythe same as material in the form of interest, such as fastenersin sheet roofing for example. Although unlikely, this may evenlead to a situation where reversing the materials may alsoreverse their anode-cathode relationship, resulting in attackduring service of a ma

21、terial which was resistant during testingas a wire.7. Procedure7.1 Components:7.1.1 The components used to construct the specimen as-semblies for this test are shown in Fig. 1.7.1.2 Prepare a 1-m length of 0.875 + 0.002-mm diameterwire of the anode material for each assembly. Other diametersmay be u

22、sed, however, the diameter of the wire may affect thetest results, so that tests may only be compared if they use wireof similar diameters. In selecting material for the wire, considerthe cold work and heat treatment of a wire may be significantlydifferent than for the component that the exposure is

23、 modeling.7.1.3 Make the cathode material into M12 3 1.75 (12 -13-UNC threaded rods or bolts, 100-mm long. Either metric orEnglish threads may be used, but results may only be comparedbetween assemblies with similar thread types.57.2 Making the Assemblies:7.2.1 Thoroughly clean and degrease all part

24、s before assem-bly in accordance with Practice G 1.7.2.2 Determine the mass of the wire to the nearest 0.0001g.7.2.3 Secure one end of the wire to a threaded rod usingsmall screws and nuts of the rod material, if possible, or ofnylon, stainless steel insulated with nylon, acetal resin, orTFE-fluoroc

25、arbon. Plastic washers are usually used under theheads of the screws. The wire may instead be secured to the rodby means of a tight O-ring wrapped around the threaded rodand the wire together.7.2.4 Wrap the wire tightly around the rod so that it liesinside the threads using a jig such as that shown

26、in Fig. 2. Thisjig is used to keep constant tension on the wire while it is beingwound. While using this jig, wear clean cotton gloves toprevent contamination of the surfaces of the wire or rod. If it isFIG. 1 Components for Making Wire-on-Bolt ExposureAssembliesFIG. 2 Constant Tension Coil Winder f

27、or Wrapping Wire orThreaded RodsG 116 99 (2004)2felt that the wire tension is not critical for the particularapplication being tested, replace the use of the jig withhand-winding.7.2.5 Wind the wire until it is in contact with roughly anaxial distance of 50 mm of threaded rod.7.2.6 Secure the free w

28、ire end to the rod by means of smallscrews and nuts made of the rod material, if possible, or ofnylon, stainless steel insulated with nylon, acetal resin, orTFE-fluorocarbon. Plastic washers are usually used under theheads of screws. The wire may instead be secured to the rod bymeans of a tight O-ri

29、ng wrapped around the threaded rod andthe wire together.7.2.7 Clip off the excess wire, if any, and determine themass of the removed piece.7.2.8 Prepare a minimum of 3 test assemblies using rods ofthe cathode material and 3 reference assemblies using anonconductive (nylon) rod for each material comb

30、ination to bestudied.7.3 Mounting and Exposure:7.3.1 Hold the assemblies vertically by screwing the rodends furthest from the wire into plastic plates. Fig. 3 shows aschematic of a completed assembly, and Fig. 4 is a photographof an actual completed assembly just before exposure.7.3.2 Mount the plat

31、es horizontally on racks such as de-scribed in Practice G 50.7.3.3 Expose the assemblies for roughly 90 days in theatmospheric site of interest.8. Measurements8.1 It is desirable to characterize or monitor the atmosphericsite during test by using one or more of the following PracticesG 84, G 91, or

32、G 92.8.2 After exposure visually inspect the specimens and notethe condition of the wires. If any sections of wire aresufficiently corroded to have dropped out of the assembly, thenthe test is invalid and a shorter duration of exposure should bechosen for a retest.8.3 Remove and clean the specimens

33、according to theprocedures specified in Practice G 1 for the material involved.8.4 Determine the final mass of the wires.9. Calculation and Interpretation of Results9.1 The wires exposed on the nonconductive rods are usedfor reference since they will have experienced no galvaniceffects, while the te

34、st wires on the cathode rods will haveexperienced additional galvanic action. It is the differencebetween the mass loss of the wires on the cathode rods andthose on the plastic rods which is an indication of galvaniccorrosion.9.2 Since the length of wire actually exposed will be slightlydifferent fo

35、r each assembly, the length differences must becorrected for. The mass loss of the wire is corrected to that fora standard 1-m length by using the mass of the wire removedas in 9.3.9.3 Calculate the mass loss per unit length of wire for eachtest and reference assembly as follows:initial mass 5 origi

36、nal wire mass 2 excess wire mass removedmass loss 5 initial mass 2 final mass after exposure!mass loss/m 5 mass loss 3 original wire mass/initial massThis mass loss should be normalized to a 90-day period bydividing by the actual number of days of exposure andmultiplying by 90.9.4 Galvanic effects a

37、re calculated as the percent differencesin the mass loss per metre between wires in the test andreference assemblies as follows:galvanic effect %!5test mass loss/m 2 reference mass loss/mreference mass loss/m3 1009.5 The average and standard deviation should be calculatedfor mass loss per unit lengt

38、h of test specimens and referencespecimens. The Students t test should be done to determine ifthese mass losses are significant at the 95 % confidence level.If the difference is not significant, the galvanic effect should bereported as zero. Statistical analyses of the results should bedone in accor

39、dance with Guide G 16.9.6 If it is found after exposure that the wire on the cathoderod lost significantly less mass than the reference (negativegalvanic effect) as determined by the t test, then it is likely thatthe wrong material was assumed to be the anode at the outset,FIG. 3 Schematic Completed

40、 Wire-on-Bolt Assemblies Mountedfor ExposureFIG. 4 Completed WireonBolt Assemblies Ready for ExposureG 116 99 (2004)3and another exposure with the roles of the two materialsreversed must be conducted. If the relationship between thetwo materials is in doubt and time is limited, dual exposuresshould

41、be conducted.9.7 Depending on the material combinations selected andcorrosivity of the atmosphere, longer or shorter exposuredurations may be needed to get measurable mass loss or toprevent loss of the wire during exposure.10. Report10.1 Report the following information:10.1.1 anode material and for

42、m, including wire diameter,10.1.2 cathode material and form, including thread typeused,10.1.3 all wire masses,10.1.4 exposure site location,10.1.5 any atmospheric conditions monitored,10.1.6 exposure duration,10.1.7 results and calculations,10.1.8 any unusual occurrences during the test,10.1.9 any u

43、nusual post exposure appearance, and10.1.10 statistical analyses of results if performed.11. Precision and Bias11.1 Intralaboratory Variability (Repeatability)Standarddeviation of the % mass loss of 6 specimens of magnesiumwire on each of 14 different bolt materials ranged from 0.26 to1.81 in a 100-

44、day exposure in a New York industrial atmo-sphere (1). For these same samples, the coefficient of variationranged from 0.059 to 0.266 %. Typical variability betweentriplicate specimens made from the CLIMAT materials is beingdeveloped in an ongoing round-robin within ASTM CommitteeG01 on Corrosion of

45、 Metals, Subcommittees G1.04 on Atmo-spheric Corrosion.11.2 Interlaboratory Variability (Reproducibility)Typicalvariability between results of identical specimens prepared bydifferent laboratories and exposed at the same location is beingdeveloped in an ongoing round-robin within ASTM CommitteeG01 o

46、n Corrosion of Metals, Subcommittees G1.04 on Atmo-spheric Corrosion.12. Keywords12.1 aluminum; architectural materials; ATCORR test; at-mospheric corrosion; atmospheric corrosivity; bolts; CLIMATtest; copper; corrosion; corrosion test; corrosivity; galvaniccorrosion; rod; wire; wire-on-bolt testREF

47、ERENCES(1) Compton, K. G., and Mendizza, A., “Galvanic Couple CorrosionStudies by Means of the Threaded Bolt and Wire Test,” Symposium onAtmospheric Corrosion of Non-Ferrous Metals, STP 175, ASTM, pp.116125, 1955.(2) Compton, K. G., Mendizza, A., and Bradley, W. W., “AtmosphericGalvanic Couple Corro

48、sion,” Corrosion, Vol 11, p. 383t, 1955.(3) Doyle, D. P., and Godard, H. G.,“ A Rapid Method for Determining theCorrosivity of the Atmosphere at Any Location,” Nature, Vol 200, No.4912, December 1963, pp. 11671168.(4) Doyle, D. P., and Godard, H. G., “Rapid Determination of Corrosivityof an Atmosphe

49、re to Aluminum,” Proceedings of the Third Interna-tional Congress on Metallic Corrosion, Vol 4, pp. 429437, MIRPublishers, Moscow, USSR, 1969.(5) Doyle, D. P., and Wright, T. E., “A Rapid Method for PredictingAdequate Service Lives for Overhead Conductors in Marine Atmo-spheres,” Paper No. 71 CP 172-PWR, presented at the IEEE WinterPower Meeting, NY, JanFeb 1971.(6) King, G. A., and Gibbs, P., “Corrosivity Mapping Around a PointSource of Pollution,” Corrosion Australasia, Vol. 11, No. 6, December1986, pp. 59.(7) King, G. A., “Assessment of the Corrosivity of the Atmosp