1、Designation: G162 99 (Reapproved 2010)Standard Practice forConducting and Evaluating Laboratory Corrosion Tests inSoils1This standard is issued under the fixed designation G162; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers procedures for conducting labora-tory corrosion tests in soils to evaluate the corrosive a
3、ttack onengineering materials.1.2 This practice covers specimen selection and preparation,test environments, and evaluation of test results.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport t
4、o 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.2. Referenced Documents2.1 ASTM Standards:2D1193 Sp
5、ecification for Reagent WaterD1654 Test Method for Evaluation of Painted or CoatedSpecimens Subjected to Corrosive EnvironmentsD2570 Test Method for Simulated Service Corrosion Test-ing of Engine CoolantsG1 Practice for Preparing, Cleaning, and Evaluating Corro-sion Test SpecimensG3 Practice for Con
6、ventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG4 Guide for Conducting Corrosion Tests in Field Applica-tionsG16 Guide for Applying Statistics to Analysis of CorrosionDataG31 Practice for Laboratory Immersion Corrosion Testingof MetalsG46 Guide for Examination and Evaluation
7、of PittingCorrosionG51 Test Method for Measuring pH of Soil for Use inCorrosion TestingG57 Test Method for Field Measurement of Soil ResistivityUsing the Wenner Four-Electrode MethodG71 Guide for Conducting and Evaluating Galvanic Corro-sion Tests in ElectrolytesG102 Practice for Calculation of Corr
8、osion Rates andRelated Information from Electrochemical Measurements3. Significance and Use3.1 This practice provides a controlled corrosive environ-ment that has been utilized to produce relative corrosioninformation.3.2 The primary application of the data from this practice isto evaluate metallic
9、materials for use in soil environments.3.3 This practice may not duplicate all field conditions andvariables such as stray currents, microbiologically influencedcorrosion, non-homogeneous conditions, and long cell corro-sion. The reproducibility of results in the practice is highlydependent on the t
10、ype of specimen tested and the evaluationcriteria selected as well as the control of the operatingvariables. In any testing program, sufficient replicates shouldbe included to establish the variability of the results.3.4 Structures and components may be made of severaldifferent metals; therefore, th
11、e practice may be used to evaluategalvanic corrosion effects in soils (see Guide G71).3.5 Structures and components may be coated with sacrifi-cial or noble metal coatings, which may be scratched orotherwise rendered discontinuous (for example, no coating onthe edges of metal strips cut from a wide
12、sheet). This test isuseful to evaluate the effect of defective metallic coatings.3.6 Structures and components may be coated or jacketedwith organic materials (for example, paints and plastics), andthese coatings and jackets may be rendered discontinuous. Thetest is useful to evaluate the effect of
13、defective or incompletelycovering coatings and jackets.3.7 The corrosivity of soils strongly depends on soluble saltcontent (related parameters are soil resistivity, see Test MethodG57, and chemistry), acidity or alkalinity (measured by soilpH, see Test Method G51), and oxygen content (loose, forexa
14、mple, sand, or compact, for example, clay, soils are extremeexamples). The manufacturer, supplier, or user, or combinationthereof, should establish the nature of the expected soil1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of
15、Subcommittee G01.10 on Corrosion inSoils.Current edition approved Feb. 1, 2010. Published March 2010. Originallyapproved in 1999. Last previous edition approved in 2004 as G162-99(2004). DOI:10.1520/G0162-99R10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cust
16、omer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.environment(s) and select the test
17、environment(s) accordingly.Multiple types of soil can be used to determine the effect of thisvariable.4. Test Apparatus and Conditions4.1 ContainerThe container for the soil shall be madefrom a material that is not affected by the soil environment andthat does not affect the soil. Container material
18、s, such as glass,plastic, or corrosion-resistant metal or alloy, can be used;however, electrically conductive containers must be electro-chemically isolated from the specimens. The size of thecontainer is determined by the volume of soil required for thetest. A minimum of 40 cm3should be used for ea
19、ch 1 cm2ofexposed metal surface area (see Fig. 1).4.2 Soil EnvironmentThe container is filled with a soilsample of choice. A soil sample from a specific outdoorlocation may be retrieved for the test, or a soil sample may beprepared with a specific property and chemistry. If necessary,physical and ch
20、emical characteristics of the soil may bedetermined.4.2.1 A field soil sample may be utilized for purposes ofconducting a soil corrosion test in a specific environment.4.2.2 Laboratory soil samples may be prepared by usingwashed sand, (that is, No. 2 silica sand) clean clay (that is,bentonite) or ot
21、her uniform known media.4.2.3 Soil ChemistryThe field soil sample and the labora-tory soil sample are saturated with a known electrolyte chosenfor the test. Typically, the electrolyte is added to the soil ofchoice in the container. A typical electrolyte for use withwashed sand is ASTM corrosive wate
22、r (see Test MethodD2570). With field soil samples, deionized or distilled water(see Test Method D2570) is commonly used. Periodically,deionized or distilled water (see Specification D1193) is addedto maintain the soil in a saturated condition. A non-saturatedcondition can be maintained if desired.4.
23、2.4 TemperatureThe test is conducted under laboratoryambient temperature unless the effect of temperature is beingevaluated.4.2.5 Test SpecimenThe test specimen is buried in the soilwithin the container and is prepared as discussed in Section 5.5. Test Specimen5.1 MaterialPrepare the test specimens
24、from the samematerial as that used in the structures or components beingstudied. Alternatively, use test specimens from the actualproducts.5.2 Size and Shape:5.2.1 The size and shape of test specimens are dependent onseveral factors and cannot be rigidly defined. When determin-ing corrosion behavior
25、 of metals in the laboratory, it isadvisable to use the largest specimens permissible within theconstraints of the test equipment. In general, the ratio ofsurface area to metal volume should be large in order to obtainmaximum corrosion loss per specimen weight. However,sufficient thickness should be
26、 employed to minimize thepossibility of perforation of the specimen during the testexposure unless an evaluation of perforation susceptibility is ofinterest. When modeling large structures or components, thesize of the specimens should be as large as practical. Whenmodeling small components, the spe
27、cimen size should be asclose as possible to that of the component modeled. When thestructure or component is made of two or more metals, thesurface area ratio of the test specimen should be similar to thestructure or component being modeled.5.2.2 When modeling service applications, the shapes of the
28、specimens should approximate the shapes in the application.Complex shapes are frequently simplified for testing purposes.For some tests, the specimen may be taken from the manufac-turing line or cut from manufactured pieces (for example, shortsections of pipes, wires, cables).5.3 Specimen Preparatio
29、n:5.3.1 Prepare the edges of the test specimens so as toeliminate all sheared or cold worked metal, except for coldworking introduced by stamping for identification. Shearingcan, in some cases, introduce residual stress that may causeconsiderable attack. Therefore, do not use specimens withsheared e
30、dges unless this effect is being evaluated. Finish theedges by machining or polishing. The slight amount of coldwork resulting from the machining process should not intro-duce serious error.5.3.2 The specimen metallurgical and surface conditionshould be similar to the application being modeled. In a
31、ll cases,remove surface contamination, such as dirt, grease, oil andthick oxides, prior to weighing and exposure to the testenvironment (see Practice G1).5.3.3 The effect of damage areas on coated specimens maybe of interest. In this circumstance, artificially introduceuniform damages, similar in si
32、ze to the expected field damage.Some methods of applying standardized mechanical damage tocoated specimens are presented in Test Method D1654.5.3.4 Introduce a specimen identification system that willendure throughout the test period. Edged notches, drilled holes,stamped numbers, and tags are some o
33、f the methods used foridentification. The identification system must not induce cor-rosion attack in any way.5.4 Number of Specimens:5.4.1 The number of scheduled periodic specimen removalsduring the test should include duplicate and, preferably, tripli-cate specimens for any given test period to de
34、termine thevariability in the corrosion behavior. The effect of the numberof replications on the evaluation of the results is set forth inPractice G16.5.4.2 If the test specimens are made of galvanically coupleddissimilar metals, control specimens should also be tested toFIG. 1 Apparatus for Conduct
35、ing Laboratory Corrosion Tests inSoilsG162 99 (2010)2provide corrosion rates of the individual metals and alloys(without coupling) for comparison. These specimens should beof the same alloys, shapes, sizes, surface, and metallurgicalcondition as the materials in the couple.6. Test Procedure6.1 Test
36、AssemblyIntroduce the test soil into the containerno less than 2 cm from the top of the container. Bury thespecimen (or specimens) within the soil. The specimen shouldnot contact the container and should be completely buriedunless the effect of partial burial is desired (see Fig. 1).6.1.1 The corros
37、ion behavior of metals in soil is influencedby the compaction of the soil around the metal and the effect ofpore structure of the soil on the oxygen transport to the metalsurface. Therefore, when simulating site conditions, the testsoil shall be compacted appropriately.6.1.2 Space the specimens (if
38、more than one is buried withina container) such that a minimum of 40 cm3of test soilsurrounds each square centimetre of exposed surface area.6.1.3 The appropriate electrolyte is introduced to the con-tainer such that the soil is saturated and the level of liquid is atthe same height as the level of
39、the soil within the container.Deionized or distilled water (see Specification D1193) is addedperiodically to maintain saturation in the soil. The containermay be loosely covered to minimize evaporation.6.1.4 To simulate conditions in which soil is not watersaturated, the distilled or deionized water
40、 is added periodicallyto maintain a water level below the test specimen.6.2 Test Duration:6.2.1 The duration of the exposure to the test environmentshould be sufficient to allow prediction of the corrosionbehavior for the entire service duration. Measure corrosiondata as a function of time until a c
41、urve is developed that onecan extrapolate to the service duration, provided that steady-state conditions have been reached and that no transientenvironmental conditions are expected in service to affect thissteady state.6.2.2 If the exposure time is extensive, some of the impor-tant constituents of
42、the test medium may be depleted. There-fore, the test environment may be altered and provide resultsthat are not representative.6.2.3 Remove test specimens based on a preplanned sched-ule.7. Evaluation of Test Specimens7.1 Measurements During ExposureData recorded duringexposure may include potentia
43、l measurements of the testspecimens and galvanic current measurements in galvaniccouples. Measure the potentials against a suitable referencehalf-cell as recommended in Practice G3. Current data can beconverted into corrosion rate based on Faradays law when allof the current is due to the corrosion
44、reaction (see PracticeG102).7.2 Measurements After Removal:7.2.1 After removal, take samples of corrosion products forchemical and physical analysis. Record visual observationsafter taking color photographs of each specimen. Clean thespecimens in accordance with Practice G1, and weigh thespecimens t
45、o determine the corrosion mass loss, which can beconverted to corrosion rate as set forth in Practice G31.Additional recommendations for specimen cleaning are inGuide G4 and Practice G31.7.2.2 Some examples in which mass loss measurements arenot always possible or meaningful are (1) specimens withor
46、ganic coating and jacketing, (2) specimens made of solderedassemblies, and (3) specimens subject only to localized corro-sion (for example, pitting or cracking). In these cases, base thecorrosion evaluation on visual assessment, loss of tensilestrength, loss of thickness, or on other measurement tec
47、h-niques. Analyze localized corrosion, such as pitting, using themethods described in Guide G46. Analyze specimens under-going crevice corrosion with depth of attack measurements andwith detailed description, including changes taking place at theedges as well as on the surfaces. In addition, measure
48、 changesin physical properties, such as tensile strength and loss ofductility. In some cases, metallographic examination of speci-men cross sections can be used to determine the depth ofcorrosion.7.2.3 Compare the behavior of galvanic test specimens tothat of exposed uncoupled controls of the indivi
49、dual anode andcathode materials. Subtracting the results found on the controlsamples from the values of the coupled specimens yields thecorrosion behavior of anode and cathode materials due tocoupling.7.2.4 Where replicate specimens are exposed, apply statis-tical analysis of the data, as set forth in Practice G16,togenerate confidence intervals for predictive purposes.8. Report8.1 Report the Following Information:8.1.1 A detailed description of the exposed specimen, in-cluding alloy and temper, metallurgical history, chemicalcomposition, processing parameters for formed part
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