ASTM G1-2003(2011) Standard Practice for Preparing Cleaning and Evaluating Corrosion Test Specimens《腐蚀试样的制备清洁处理和评估用标准操作规程》.pdf

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1、Designation: G1 03 (Reapproved 2011)Standard Practice forPreparing, Cleaning, and Evaluating Corrosion TestSpecimens1This standard is issued under the fixed designation G1; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year o

2、f 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 practice covers suggested procedures for preparingbare, solid metal specimens for tests, for removing corrosion

3、products after the test has been completed, and for evaluatingthe corrosion damage that has occurred. Emphasis is placed onprocedures related to the evaluation of corrosion by mass lossand pitting measurements. (WarningIn many cases thecorrosion product on the reactive metals titanium and zirco-nium

4、 is a hard and tightly bonded oxide that defies removal bychemical or ordinary mechanical means. In many such cases,corrosion rates are established by mass gain rather than massloss.)1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisst

5、andard.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 to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For spe

6、cificwarning statements, see 1.1 and 7.2.2. Referenced Documents2.1 ASTM Standards:2A262 Practices for Detecting Susceptibility to IntergranularAttack in Austenitic Stainless SteelsD1193 Specification for Reagent WaterD1384 Test Method for Corrosion Test for Engine Coolantsin GlasswareD2776 Methods

7、of Test for Corrosivity of Water in theAbsence of Heat Transfer (Electrical Methods)3G15 Terminology Relating to Corrosion and CorrosionTesting3G16 Guide for Applying Statistics to Analysis of CorrosionDataG31 Practice for Laboratory Immersion Corrosion Testingof MetalsG33 Practice for Recording Dat

8、a from Atmospheric Corro-sion Tests of Metallic-Coated Steel SpecimensG46 Guide for Examination and Evaluation of PittingCorrosionG50 Practice for Conducting Atmospheric Corrosion Testson MetalsG78 Guide for Crevice Corrosion Testing of Iron-Base andNickel-Base Stainless Alloys in Seawater and Other

9、Chloride-Containing Aqueous Environments3. Terminology3.1 See Terminology G15 for terms used in this practice.4. Significance and Use4.1 The procedures given are designed to remove corrosionproducts without significant removal of base metal. This allowsan accurate determination of the mass loss of t

10、he metal or alloythat occurred during exposure to the corrosive environment.4.2 These procedures, in some cases, may apply to metalcoatings. However, possible effects from the substrate must beconsidered.5. Reagents and Materials5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests

11、. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society where1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of Subcommitt

12、ee G01.05 on LaboratoryCorrosion Tests.Current edition approved Dec. 1, 2011. Published April 2012. Originallyapproved in 1967. Last previous edition approved in 2003 as G12003. DOI:10.1520/G0001-03R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Serv

13、ice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C70

14、0, West Conshohocken, PA 19428-2959, United States.such specifications are available.4Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.5.2 Purity of WaterUnless otherwise indi

15、cated, referencesto water shall be understood to mean reagent water as definedby Type IV of Specification D1193.6. Methods for Preparing Specimens for Test6.1 For laboratory corrosion tests that simulate exposure toservice environments, a commercial surface, closely resem-bling the one that would be

16、 used in service, will yield the mostmeaningful results.6.2 It is desirable to mark specimens used in corrosion testswith a unique designation during preparation. Several tech-niques may be used depending on the type of specimen andtest.6.2.1 Stencil or StampMost metallic specimens may bemarked by s

17、tenciling, that is, imprinting the designation codeinto the metal surface using hardened steel stencil stamps hitwith a hammer. The resulting imprint will be visible even aftersubstantial corrosion has occurred. However, this procedureintroduces localized strained regions and the possibility ofsuper

18、ficial iron contamination in the marked area.6.2.2 Electric engraving by means of a vibratory markingtool may be used when the extent of corrosion damage isknown to be small. However, this approach to marking is muchmore susceptible to having the marks lost as a result ofcorrosion damage during test

19、ing.6.2.3 Edge notching is especially applicable when extensivecorrosion and accumulation of corrosion products is antici-pated. Long term atmospheric tests and sea water immersiontests on steel alloys are examples where this approach isapplicable. It is necessary to develop a code system when using

20、edge notches.6.2.4 Drilled holes may also be used to identify specimenswhen extensive metal loss, accumulation of corrosion products,or heavy scaling is anticipated. Drilled holes may be simplerand less costly than edge notching. A code system must bedeveloped when using drilled holes. Punched holes

21、 should notbe used as they introduce residual strain.6.2.5 When it is undesirable to deform the surface ofspecimens after preparation procedures, for example, whentesting coated surfaces, tags may be used for specimen identi-fication. A metal or plastic wire can be used to attach the tag tothe speci

22、men and the specimen identification can be stampedon the tag. It is important to ensure that neither the tag nor thewire will corrode or degrade in the test environment. It is alsoimportant to be sure that there are no galvanic interactionsbetween the tag, wire, and specimen.6.3 For more searching t

23、ests of either the metal or theenvironment, standard surface finishes may be preferred. Asuitable procedure might be:6.3.1 Degrease in an organic solvent or hot alkaline cleaner.(See also Practice G31.)NOTE 1Hot alkalies and chlorinated solvents may attack some metals.NOTE 2Ultrasonic cleaning may b

24、e beneficial in both pre-test andpost-test cleaning procedures.6.3.2 Pickle in an appropriate solution if oxides or tarnishare present. In some cases the chemical cleaners described inSection 6 will suffice.NOTE 3Pickling may cause localized corrosion on some materials.6.3.3 Abrade with a slurry of

25、an appropriate abrasive or withan abrasive paper (see Practices A262 and Test MethodD1384). The edges as well as the faces of the specimens shouldbe abraded to remove burrs.6.3.4 Rinse thoroughly, hot air dry, and store in desiccator.6.4 When specimen preparation changes the metallurgicalcondition o

26、f the metal, other methods should be chosen or themetallurgical condition must be corrected by subsequent treat-ment. For example, shearing a specimen to size will cold workand may possibly fracture the edges. Edges should be ma-chined.6.5 The clean, dry specimens should be measured andweighed. Dime

27、nsions determined to the third significant figureand mass determined to the fifth significant figure are sug-gested. When more significant figures are available on themeasuring instruments, they should be recorded.7. Methods for Cleaning After Testing7.1 Corrosion product removal procedures can be d

28、ividedinto three general categories: mechanical, chemical, and elec-trolytic.7.1.1 An ideal procedure should remove only corrosionproducts and not result in removal of any base metal. Todetermine the mass loss of the base metal when removingcorrosion products, replicate uncorroded control specimenss

29、hould be cleaned by the same procedure being used on the testspecimen. By weighing the control specimen before and aftercleaning, the extent of metal loss resulting from cleaning canbe utilized to correct the corrosion mass loss.NOTE 4It is desirable to scrape samples of corrosion products beforeusi

30、ng any chemical techniques to remove them. These scrapings can thenbe subjected to various forms of analyses, including perhaps X-raydiffraction to determine crystal forms as well as chemical analyses to lookfor specific corrodants, such as chlorides. All of the chemical techniquesthat are discussed

31、 in Section 7 tend to destroy the corrosion products andthereby lose the information contained in these corrosion products. Caremay be required so that uncorroded metal is not removed with thecorrosion products.7.1.2 The procedure given in 7.1.1 may not be reliable whenheavily corroded specimens are

32、 to be cleaned. The applicationof replicate cleaning procedures to specimens with corrodedsurfaces will often, even in the absence of corrosion products,result in continuing mass losses. This is because a corrodedsurface, particularly of a multiphase alloy, is often moresusceptible than a freshly ma

33、chined or polished surface tocorrosion by the cleaning procedure. In such cases, the4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for

34、LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.G1 03 (2011)2following method of determining the mass loss due to thecleaning procedure is preferred.7.1.2.1 The cleaning procedure s

35、hould be repeated on speci-mens several times. The mass loss should be determined aftereach cleaning by weighing the specimen.7.1.2.2 The mass loss should be graphed as a function of thenumber of equal cleaning cycles as shown in Fig. 1. Two lineswill be obtained: AB and BC. The latter will correspo

36、nd tocorrosion of the metal after removal of corrosion products. Themass loss due to corrosion will correspond approximately topoint B.7.1.2.3 To minimize uncertainty associated with corrosionof the metal by the cleaning method, a method should bechosen to provide the lowest slope (near to horizonta

37、l) of lineBC.7.1.3 Repeated treatment may be required for completeremoval of corrosion products. Removal can often be con-firmed by examination with a low power microscope (forexample, 73 to 303). This is particularly useful with pittedsurfaces when corrosion products may accumulate in pits. Thisrep

38、eated treatment may also be necessary because of therequirements of 7.1.2.1. Following the final treatment, thespecimens should be thoroughly rinsed and immediately dried.7.1.4 All cleaning solutions shall be prepared with waterand reagent grade chemicals.7.2 Chemical procedures involve immersion of

39、 the corro-sion test specimen in a specific solution that is designed toremove the corrosion products with minimal dissolution of anybase metal. Several procedures are listed in Table A1.1. Thechoice of chemical procedure to be used is partly a matter oftrial and error to establish the most effectiv

40、e method for aspecific metal and type of corrosion product scale.(WarningThese methods may be hazardous to personnel).7.2.1 Chemical cleaning is often preceded by light brushing(non metallic bristle) or ultrasonic cleaning of the test speci-men to remove loose, bulky corrosion products.7.2.2 Intermi

41、ttent removal of specimens from the cleaningsolution for light brushing or ultrasonic cleaning can oftenfacilitate the removal of tightly adherent corrosion products.7.2.3 Chemical cleaning is often followed by light brushingor ultrasonic cleaning in reagent water to remove looseproducts.7.3 Electro

42、lytic cleaning can also be utilized for removal ofcorrosion products. Several useful methods for corrosion testspecimens of iron, cast iron, or steel are given in Table A2.1.7.3.1 Electrolytic cleaning should be preceded by brushingor ultrasonic cleaning of the test specimen to remove loose,bulky co

43、rrosion products. Brushing or ultrasonic cleaningshould also follow the electrolytic cleaning to remove anyloose slime or deposits. This will help to minimize anyredeposition of metal from reducible corrosion products thatwould reduce the apparent mass loss.7.4 Mechanical procedures can include scra

44、ping, scrubbing,brushing, ultrasonic cleaning, mechanical shocking, and im-pact blasting (for example, grit blasting, water-jet blasting, andso forth). These methods are often utilized to remove heavilyencrusted corrosion products. Scrubbing with a nonmetallicbristle brush and a mild abrasive-distil

45、led water slurry can alsobe used to remove corrosion products.7.4.1 Vigorous mechanical cleaning may result in the re-moval of some base metal; therefore, care should be exercised.These should be used only when other methods fail to provideadequate removal of corrosion products. As with other meth-o

46、ds, correction for metal loss due to the cleaning method isrecommended. The mechanical forces used in cleaning shouldbe held as nearly constant as possible.8. Assessment of Corrosion Damage8.1 The initial total surface area of the specimen (makingcorrections for the areas associated with mounting ho

47、les) andthe mass lost during the test are determined. The averagecorrosion rate may then be obtained as follows:Corrosion Rate 5 K 3 W!/A 3 T 3 D! (1)where:K = a constant (see 8.1.2),T = time of exposure in hours,A = area in cm2,W = mass loss in grams, andD = density in g/cm3(see Appendix X1).8.1.1

48、Corrosion rates are not necessarily constant with timeof exposure. See Practice G31 for further guidance.8.1.2 Many different units are used to express corrosionrates. Using the units in 7.1 for T, A, W, and D, the corrosionrate can be calculated in a variety of units with the followingappropriate v

49、alue of K:Corrosion Rate Units DesiredConstant (K) in CorrosionRate Equationmils per year (mpy) 3.45 3 106inches per year (ipy) 3.45 3 103inches per month (ipm) 2.87 3 102millimetres per year (mm/y) 8.76 3 104micrometres per year (um/y) 8.76 3 107picometres per second (pm/s) 2.78 3 106grams per square meter per hour (g/m2h) 1.00 3 1043 Dmilligrams per square decimeter per day (mdd) 2.40 3 1063 Dmicrograms per square meter per second (g/m2s) 2.78 3 1063 DFIG. 1 Mass Loss of Corroded Specimens Resulting fromRepetitive Cleaning CyclesG1 03 (2011)3NOTE 5If desired, these