1、Designation NACE TM0169/ G31 12aStandard Guide forLaboratory Immersion Corrosion Testing of Metals1This standard is issued under the fixed designation G31; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.1
2、. Scope1.1 This guide covers and describes the factors that influ-ence laboratory immersion corrosion tests, particularly massloss tests. These factors include apparatus, sampling, testspecimen, test conditions (test solution composition, tempera-ture, gas sparging, fluid motion, solution volume, me
3、thod ofsupporting test specimens, duration of test), methods of clean-ing test specimens, interpretation of results, and calculation ofcorrosion rates. This guide also emphasizes the importance ofrecording all pertinent data and provides a checklist forreporting test data.1.2 The specific evaluation
4、 of localized attack, environmen-tally assisted cracking, and effects of solution flow are notwithin the scope of this guide.1.3 This guide is intended to be used by those designinglaboratory immersion tests who may not be familiar with all ofthe variables to consider and the pitfalls that could be
5、encoun-tered when designing and conducting this kind of testing. Itshould be used as a reference to ensure that the test will allowgeneration of data relevant to the application with the mini-mum of interferences.1.4 The values stated in SI units are to be regarded as thestandard. The values given i
6、n parentheses are for informationonly.1.5 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 li
7、mitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A262 Practices for Detecting Susceptibility to IntergranularAttack in Austenitic Stainless SteelsD1193 Specification for Reagent WaterE8 Test Methods for Tension Testing of Metallic MaterialsE300 Practice for Sampling Industrial Chemi
8、calsG1 Practice for Preparing, Cleaning, and Evaluating Corro-sion Test SpecimensG28 Test Methods for Detecting Susceptibility to Inter-granular Corrosion in Wrought, Nickel-Rich, Chromium-Bearing AlloysG34 Test Method for Exfoliation Corrosion Susceptibilityin 2XXX and 7XXX Series Aluminum Alloys (
9、EXCOTest)G46 Guide for Examination and Evaluation of PittingCorrosionG48 Test Methods for Pitting and Crevice Corrosion Resis-tance of Stainless Steels and Related Alloys by Use ofFerric Chloride SolutionG66 Test Method for Visual Assessment of ExfoliationCorrosion Susceptibility of 5XXX Series Alum
10、inum Al-loys (ASSET Test)G67 Test Method for Determining the Susceptibility toIntergranular Corrosion of 5XXX SeriesAluminumAlloysby Mass Loss After Exposure to Nitric Acid (NAMLTTest)G71 Guide for Conducting and Evaluating Galvanic Corro-sion Tests in ElectrolytesG78 Guide for Crevice Corrosion Tes
11、ting of Iron-Base andNickel-Base Stainless Alloys in Seawater and OtherChloride-Containing Aqueous EnvironmentsG82 Guide for Development and Use of a Galvanic Seriesfor Predicting Galvanic Corrosion PerformanceG107 Guide for Formats for Collection and Compilation ofCorrosion Data for Metals for Comp
12、uterized DatabaseInputG108 Test Method for Electrochemical Reactivation (EPR)for Detecting Sensitization of AISI Type 304 and 304LStainless SteelsG110 Practice for Evaluating Intergranular Corrosion Re-sistance of Heat TreatableAluminumAlloys by Immersionin Sodium Chloride + Hydrogen Peroxide Soluti
13、onG112 Guide for Conducting Exfoliation Corrosion Tests inAluminum AlloysG116 Practice for Conducting Wire-on-Bolt Test for Atmo-spheric Galvanic CorrosionG135 Guide for Computerized Exchange of Corrosion Datafor MetalsG170 Guide for Evaluating and Qualifying Oilfield andRefinery Corrosion Inhibitor
14、s in the LaboratoryG184 Practice for Evaluating and Qualifying Oil Field andRefinery Corrosion Inhibitors Using Rotating CageG185 Practice for Evaluating and Qualifying Oil Field andRefinery Corrosion Inhibitors Using the Rotating CylinderElectrode1This guide is under the jurisdiction of NACE/ASTM C
15、ommittee J01, JointCommittee on Corrosion, and is the direct responsibility of Subcommittee J01.01,Working Group on Laboratory Immersion Tests.Current edition approved July 1, 2012. Published October 2012. Originallyapproved in 1972. Last previousASTM edition approved in 2012 as G3112. NACEedition o
16、riginally approved in 1969. Last previous NACE edition approved in 2000as TM0169-2000. DOI: 10.1520/G0031-12A.2For referenced ASTM standards, visit the ASTM Web site, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the s
17、tandards Document Summary page onthe ASTM Web site. For NACE standards, visit the NACE Web site, www.nace.org,or contact NACE FirstService at firstservicenace.org.1 NACE International/ASTM International 2012 All rights reserved2.2 NACE/ASTM Standards:2G193 Terminology and Acronyms Relating to Corros
18、ion2.3 NACE International Standards:2SP0690 Standard Format for Collection and Compilation ofData for Computerized Material Corrosion ResistanceDatabase Input2.4 International Organization for Standardization (ISO)Standards:3ISO 3651-1 Austenitic Stainless Steels Determination ofresistance to interg
19、ranular corrosion of stainless steels Part I: Austenitic and ferritic-austenitic (duplex) stainlesssteels Corrosion test in nitric acid medium by measure-ment of loss in mass (Huey test)ISO 3651-2 Determination of resistance to intergranularcorrosion of stainless steels Part 2: Ferritic, austenitica
20、nd ferritic-austenitic (duplex) stainless steels corrosiontest in media containing sulfuric acidISO 6509 Corrosion of metals and alloys Determinationof dezincification resistance of brassISO 8407 Corrosion of metals and alloys Removal ofcorrosion products from corrosion test specimensISO 8993 Anodiz
21、ed aluminum and aluminum alloys Rating system for the evaluation of pitting corrosion Chart methodISO 8994 Anodized aluminum and aluminum alloys Rating system for the evaluation of pitting corrosion Grid methodISO 9400 Nickel-based alloys Determination of resistanceto intergranular corrosionISO 1146
22、3 Corrosion of metals and alloys Evaluation ofpitting corrosionISO 11845 Corrosion of metals and alloys General prin-ciples for corrosion testingISO 11846 Corrosion of metals and alloys Determinationof resistance to intergranular corrosion of solution heat-treatable aluminum alloysISO 11881 Corrosio
23、n of metals and alloys Exfoliationcorrosion testing of aluminum alloys3. Terminology3.1 For definitions of terms used in this guide, see NACE/ASTM Terminology G193.4. Significance and Use4.1 Corrosion testing by its very nature precludes completestandardization. This standard, rather than a standard
24、izedprocedure, is presented as a guide so that some of the pitfallsof such testing may be avoided.4.2 Experience has shown that all metals and alloys do notrespond alike to the many factors that affect corrosion and thataccelerated corrosion tests give indicative results only, or mayeven be entirely
25、 misleading. It is impractical to propose aninflexible standard laboratory corrosion testing procedure forgeneral use, except for material qualification tests wherestandardization is required. One purpose for this guide is topromote better correlation of results in the future and thereduction of con
26、flicting reports through a more detailed record-ing of meaningful factors and conditions.4.3 In designing any corrosion test, consideration should begiven to the various factors discussed in this guide, becausethese factors have been found to affect the results obtained.5. Factors Affecting Corrosio
27、n Behavior5.1 The methods and procedures described herein representthe best current practices for conducting laboratory immersioncorrosion tests as developed by corrosion specialists in theprocess industries. For proper interpretation of the resultsobtained, the specific influence of one or more of
28、the followingvariables should be considered.5.1.1 Metal specimens immersed in a specific hot liquidmay not corrode at the same rate or in the same manner as inequipment where the metal acts as a heat transfer medium inheating or cooling the liquid. If the influence of heat transfereffects is specifi
29、cally of interest, specialized procedures (inwhich the corrosion specimen serves as a heat transfer agent)shall be employed.5.1.2 In laboratory immersion tests, the motion of theenvironment relative to the specimens will normally be pro-vided by convection currents, gas sparging, or boiling. If thes
30、pecific effects of fluid flow are to be studied, special tech-niques shall be employed to create and control the relativemotion between the environment and the test specimens. Thismay be accomplished by either moving the environment asthrough a tube or mechanical stirrer or by moving the speci-mens
31、as by rotation.5.1.3 The behavior of certain metals and alloys may beprofoundly influenced by the presence of dissolved oxygen. Ifthis is a factor to be considered in a specific test, the solutionshould be air saturated at 1 atm or de-aerated, as appropriate.5.1.4 In some cases, the rate of corrosio
32、n may be governedby other minor constituents in the solution, in which case theywill have to be continually or intermittently replenished bychanging the solution in the test.5.1.5 Corrosion products may have undesirable effects on achemical product. The amount of possible contamination cansometimes
33、be estimated from the loss in mass of the specimenor from the changes in the chemical composition of the testenvironment. This is discussed in more detail in 9.8.3.5.1.6 Corrosion products from the specimen may influencethe corrosion rate of the metal itself or of different metalsexposed at the same
34、 time. For example, the accumulation ofcupric ions in the testing of copper alloys in intermediatestrengths of sulfuric acid will accelerate the corrosion ofcopper alloys, as compared to the rates that would be obtainedif the corrosion products were continually removed. It may benecessary to expose
35、only alloys of the same general type in thesame testing apparatus unless it is known that no interactionswill occur.5.1.7 Specimen corrosion testing is frequently designed toinvestigate general corrosion only. There are a number of other3Available from International Organization for Standardization
36、(ISO), 1, ch. dela Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.NACE TM0169/G31 12a2 NACE International/ASTM International 2012 All rights reservedforms of corrosion of which one shall be aware in the designand interpretation of corrosion tests.5.1.7.1 Galvanic cor
37、rosion may be investigated by specialdevices that couple one specimen to another in electricalcontact. The behavior of the specimens in this galvanic coupleis compared with that of insulated specimens exposed on thesame holder. It should be observed, however, that galvaniccorrosion can be greatly af
38、fected by the area ratios of therespective metals, the separation between the metals, and theconductivity of the electrolyte. The coupling of corrosionspecimens then yields only qualitative results, as a particularspecimen reflects only the relationship between these twometals at the particular area
39、 ratio involved. Galvanic corrosiontesting is further discussed in ASTM Guide G71, ASTM GuideG82, and ASTM Practice G116.5.1.7.2 Crevice corrosion or concentration cell corrosionmay occur where the metal surface is partially blocked fromthe corroding liquid as under a spacer or supporting hook. It i
40、snecessary to evaluate this localized corrosion separately fromthe overall mass loss. Crevice corrosion testing is furtherdiscussed in ASTM Test Methods G48 and ASTM Guide G78.5.1.7.3 Selective corrosion at the grain boundaries (forexample, intergranular corrosion of sensitized austenitic stain-less
41、 steels) will not be readily observable in mass lossmeasurements unless the attack is severe enough to cause graindropping, and often requires microscopic examination of thespecimens after exposure. This type of corrosion may alsoresult in loss of strength or ductility of materials. Such lossescan b
42、e evaluated by mechanical property determinations beforeand after exposure to the test environment. Testing for selectivecorrosion is further discussed inASTM PracticesA262,ASTMTest Methods G28, G34, G66, G67, G108, G110, and ASTMGuide G112 and ISO 3651-1, ISO 3651-2, ISO 9400,ISO 11846, and ISO 118
43、81.5.1.7.4 Dealloying or “parting” corrosion is a condition inwhich one constituent is selectively removed from an alloy, asin the dezincification of brass or the graphitization of cast iron.Close attention and a more sophisticated evaluation than asimple mass loss measurement are required to detect
44、 thisphenomenon. Dealloying testing is further discussed inISO 6509.5.1.7.5 Certain metals and alloys are subject to a highlylocalized type of attack called pitting corrosion. This cannot beevaluated by mass loss alone. Pitting is a statistical phenom-enon and the incidence of pitting may be directl
45、y related to thearea of metal exposed. For example, a small specimen is not asprone to exhibit pitting as a large one and it is possible to missthe phenomenon altogether in the corrosion testing of certainalloys, such as the AISI Type 300 series stainless steels inchloride-containing environments. P
46、itting testing is furtherdiscussed inASTM Guide G46,ASTM Test Methods G48, andISO 8993, ISO 8994, and ISO 11463.5.1.7.6 Most metals and alloys are subject to environmen-tally assisted cracking under some circumstances. This crack-ing occurs under conditions of applied or residual tensile stress,and
47、it may or may not be visible to the unaided eye or uponcasual inspection. A metallographic examination may confirmthe presence of environmentally assisted cracking. This usuallyoccurs with no significant loss in mass of the test specimen,although certain refractory metals are an exception to theseob
48、servations. Generally, if cracking is observed on the speci-men, it can be taken as positive indication of susceptibility,whereas failure to exhibit this phenomenon means that it didnot occur under the duration and specific conditions of the test.Separate and special techniques are employed for the
49、specificevaluation of the susceptibility of metals and alloys to envi-ronmentally assisted cracking. Multiple standards from manydifferent organizations are available to describe stress-corrosion cracking tests.5.2 The use of welded specimens is sometimes desirable,because some welds may be cathodic or anodic to the parentmetal and may affect the corrosion rate.5.2.1 The heat-affected zone is also of importance butshould be studied separately because welds on test specimensmay not adequately reproduce heat input or size effects offull-size vessels.5.2.
