1、Designation: G 48 03 (Reapproved 2009)Standard Test Methods forPitting and Crevice Corrosion Resistance of StainlessSteels and Related Alloys by Use of Ferric ChlorideSolution1This standard is issued under the fixed designation G 48; the number immediately following the designation indicates the yea
2、r of originaladoption 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 These test methods cover procedures for the determina-t
3、ion of the resistance of stainless steels and related alloys topitting and crevice corrosion (see Terminology G15) whenexposed to oxidizing chloride environments. Six proceduresare described and identified as Methods A, B, C, D, E, and F.1.1.1 Method AFerric chloride pitting test.1.1.2 Method BFerri
4、c chloride crevice test.1.1.3 Method CCritical pitting temperature test fornickel-base and chromium-bearing alloys.1.1.4 Method DCritical crevice temperature test fornickel-base and chromium-bearing alloys.1.1.5 Method ECritical pitting temperature test for stain-less steels.1.1.6 Method FCritical c
5、revice temperature test for stain-less steels.1.2 Method A is designed to determine the relative pittingresistance of stainless steels and nickel-base, chromium-bearing alloys, whereas Method B can be used for determiningboth the pitting and crevice corrosion resistance of these alloys.Methods C, D,
6、 E and F allow for a ranking of alloys byminimum (critical) temperature to cause initiation of pittingcorrosion and crevice corrosion, respectively, of stainlesssteels, nickel-base and chromium-bearing alloys in a standardferric chloride solution.1.3 These tests may be used to determine the effects
7、ofalloying additives, heat treatment, and surface finishes onpitting and crevice corrosion resistance.1.4 The values stated in SI units are to be regarded as thestandard. Other units are given in parentheses for informationonly.1.5 This standard does not purport to address all of thesafety concerns,
8、 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:2A 262 Practices for Detecting Susceptibility
9、 to Intergranu-lar Attack in Austenitic Stainless SteelsD 1193 Specification for Reagent WaterE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1338 Guide for Identification of Metals and Alloys inComputerized Material Property DatabasesG1 Practice fo
10、r Preparing, Cleaning, and Evaluating Cor-rosion Test SpecimensG15 Terminology Relating to Corrosion and CorrosionTestingG46 Guide for Examination and Evaluation of PittingCorrosionG 107 Guide for Formats for Collection and Compilation ofCorrosion Data for Metals for Computerized DatabaseInput3. Ter
11、minology3.1 Definitions of Terms Specific to This Standard:3.1.1 critical crevice temperature, nthe minimum tem-perature (C) to produce crevice attack at least 0.025-mm(0.001-in.) deep on the bold surface of the specimen beneaththe crevice washer, edge attack ignored.3.1.2 critical pitting temperatu
12、re, n the minimum tem-perature (C) to produce pitting attack at least 0.025-mm(0.001-in.) deep on the bold surface of the specimen, edgeattack ignored.3.2 The terminology used herein, if not specifically definedotherwise, shall be in accordance with Terminology G15.Definitions provided herein and no
13、t given in Terminology G15are limited only to this standard.4. Significance and Use4.1 These test methods describe laboratory tests for com-paring the resistance of stainless steels and related alloys to the1These test methods are under the jurisdiction of ASTM Committee G01 onCorrosion of Metals an
14、d are the direct responsibility of Subcommittee G01.05 onLaboratory Corrosion Tests.Current edition approved May 1, 2009. Published May 2009. Originallyapproved in 1976. Last previous edition approved in 2003 as G 4803.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact A
15、STM Customer 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.initiation of pitting and c
16、revice corrosion. The results may beused for ranking alloys in order of increasing resistance topitting and crevice corrosion initiation under the specificconditions of these methods. Methods A and B are designed tocause the breakdown of Type 304 at room temperature.4.2 The use of ferric chloride so
17、lutions is justified because itis related to, but not the same as, that within a pit or crevice siteon a ferrous alloy in chloride bearing environments (1, 2).3Thepresence of an inert crevice former of consistent dimension ona surface is regarded as sufficient specification of crevicegeometry to ass
18、ess relative crevice corrosion susceptibility.4.3 The relative performance of alloys in ferric chloridesolution tests has been correlated to performance in certain realenvironments, such as natural seawater at ambient temperature(3) and strongly oxidizing, low pH, chloride containing envi-ronments (
19、4), but several exceptions have been reported (4-7).4.4 Methods A, B, C, D, E, and F can be used to rank therelative resistance of stainless steels and nickel base alloys topitting and crevice corrosion in chloride-containing environ-ments. No statement can be made about resistance of alloys inenvir
20、onments that do not contain chlorides.4.4.1 Methods A, B, C, D, E, and F were designed toaccelerate the time to initiate localized corrosion relative tomost natural environments. Consequently, the degree of corro-sion damage that occurs during testing will generally be greaterthan that in natural en
21、vironments in any similar time period.4.4.2 No statement regarding localized corrosion propaga-tion can be made based on the results of Methods A, B, C, D,EorF.4.4.3 Surface preparation can significantly influence results.Therefore, grinding and pickling of the specimen will meanthat the results may
22、 not be representative of the conditions ofthe actual piece from which the sample was taken.NOTE 1Grinding or pickling on stainless steel surfaces may destroythe passive layer. A 24-h air passivation after grinding or pickling issufficient to minimize these differences (8).4.4.4 The procedures in Me
23、thods C, D, E and F formeasuring critical pitting corrosion temperature and criticalcrevice corrosion temperature have no bias because the valuesare defined only in terms of these test methods.5. Apparatus5.1 GlasswareMethods A, B, C, D, E, and F provide anoption to use either wide mouth flasks or s
24、uitable sized testtubes. Condensers are required for elevated temperature testingwhen solution evaporation may occur. Glass cradles or hooksalso may be required.5.1.1 Flask Requirements, 1000-mL wide mouth. Tall formor Erlenmeyer flasks can be used. The mouth of the flask shallhave a diameter of abo
25、ut 40 mm (1.6 in.) to allow passage ofthe test specimen and the support.5.1.2 Test Tube Requirements, the diameter of the test tubeshall also be about 40 mm (1.6 in.) in diameter. If testingrequires use of a condenser (described below), the test tubelength shall be about 300 mm (about 12 in.); other
26、wise, thelength can be about 150 to 200 mm (about 6 in. to 8 in.).5.1.3 Condensers, Vents and Covers:5.1.3.1 A variety of condensers may be used in conjunctionwith the flasks described in 5.1.1. These include the coldfinger-type (see, for example, Practices A 262, Practice C) orAllihn type condenser
27、s having straight tube ends or taperedground joints. Straight end condensers can be inserted througha bored rubber stopper. Likewise, a simple U tube condensercan be fashioned.NOTE 2The use of ground joint condensers requires that the mouth ofthe flask have a corresponding joint.5.1.3.2 U Tube Conde
28、nsers, fitted through holes in anappropriate size rubber stopper can be used in conjunction withthe 300-mm test tube described in 5.1.2.5.1.3.3 When evaporation is not a significant problem,flasks can be covered with a watch glass. Also, flasks as wellas test tubes can be covered with loosely fitted
29、 stoppers orplastic or paraffin type wraps.NOTE 3Venting must always be considered due to the possible buildup of gas pressure that may result from the corrosion process.5.1.4 Specimen Supports:5.1.4.1 One advantage of using test tubes is that specimensupports are not required. However, placement of
30、 the specimendoes create the possible opportunity for crevice corrosion tooccur along the edge.NOTE 4See 14.2 concerning edge attack.5.1.4.2 When using flasks, specimens can be supported oncradles or hooks. Cradles, such as those shown in Fig. 1,eliminate the necessity for drilling a support hole in
31、 the testspecimen. While the use of hooks requires that a specimensupport hole be provided, the hooks, as contrasted to the cradle,are easier to fashion. Moreover, they create only one potentialcrevice site whereas multiple sites are possible with the cradle.NOTE 5A TFE-fluorocarbon cradle may be su
32、bstituted for glass.5.1.4.3 The use of supports for Methods B, D, and F crevicecorrosion specimens is optional.5.2 Water or Oil Bath, constant temperature.5.2.1 For Methods A and B, the recommended test tempera-tures are 22 6 2C or 50 6 2C, or both.5.2.2 For Methods C, D, E, and F, the bath shall ha
33、ve thecapability of providing constant temperature between 0C and85C 6 1C.5.3 Crevice FormersMethod B:5.3.1 Cylindrical TFE-fluorocarbon Blocks, two for eachtest specimen. Each block shall be 12.7-mm (0.5 in.) indiameter and 12.7-mm high, with perpendicular grooves1.6-mm (0.063 in.) wide and 1.6-mm
34、deep cut in the top ofeach cylinder for retention of the O-ring or rubber bands.Blocks can be machined from bar or rod stock.5.3.2 Fluorinated Elastomers O-rings, or Rubber Bands,(low sulfur (0.02 % max), two for each test specimen.NOTE 6It is good practice to use all O-rings or all rubber bands in
35、agiven test program.3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.G 48 03 (2009)25.3.2.1 O-rings shall be 1.75 mm (0.070 in.) in crosssection; one ring with an inside diameter of about 20 mm (0.8in.) and one with an inside diameter of about 30 mm (1.
36、1 in.).Rubber bands shall be one No. 12 (38-mm (1.5-in.) long) andone No. 14 (51-mm (2-in.) long).NOTE 7Rubber bands or O-rings can be boiled in water prior to useto ensure the removal of water-soluble ingredients that might affectcorrosion.5.4 Crevice FormersMethods D and F:5.4.1 A Multiple Crevice
37、 Assembly (MCA), consisting oftwo TFE-fluorocarbon segmented washers, each having anumber of grooves and plateaus, shall be used. The crevicedesign shown in Fig. 2 is one of a number of variations of themultiple crevice assembly that is in use and commerciallyavailable.45.4.2 Reuse of Multiple Crevi
38、ce Assemblies, when as-sembled to the specified torque, the TFE-fluorocarbon seg-mented washers should not deform during testing. Beforereuse, each washer should be inspected for evidence ofdistortion and other damage. If so affected, they should bediscarded. In some cases, the crevice formers may b
39、ecomestained with corrosion products from the tested alloy. Gener-ally, this staining can be removed by immersion in dilute HCl(for example, 5-10% by volume) at room temperature, fol-lowed by brushing with mild detergent and through rinsingwith water.5.4.3 Fasteners, one alloy UNS N10276 (or similar
40、ly resis-tant alloy) fastener is required for each assembly. Eachassembly comprises a threaded bolt and nut plus two washers.The bolt length shall be sized to allow passage through themouth of the glassware described in 5.1.5.5 Tools and Instruments:5.5.1 A 6.35-mm (14-in.) torque limiting nut drive
41、r isrequired for assembly of the Methods D and F crevice testspecimen.5.5.2 Low Power Microscope, (for example, 203 magnifi-cation) for pit detection.5.5.3 Needle Point Dial Depth Indicator or Focusing Mi-croscope, to determine the depth of pitting or crevice corro-sion, or both.4The sole source of
42、supply of the apparatus known to the committee at this timeis Metal Samples Co., Inc., P.O. Box 8, Route 1 Box 152, Munford, AL 36268. Ifyou are aware of alternative suppliers, please provide this information to ASTMHeadquarters. Your comments will receive careful consideration at a meeting of there
43、sponsible technical committee,1which you may attend.FIG. 1 Examples of Glass Cradles that Can Be Used to Support the SpecimenFIG. 2 TFE-fluorocarbon Crevice WashersG 48 03 (2009)35.5.4 Electronic Balance (optional), to determine specimenmass to the nearest 0.0001 g.5.5.5 Camera (optional), to photog
44、raphically record themode and extent of any localized corrosion.6. Ferric Chloride Test Solution6.1 For Methods A and B, dissolve 100 g of reagent gradeferric chloride, FeCl36H2O, in 900 mL of Type IV reagentwater (Specification D 1193) (about 6 % FeCl3by mass). Filterthrough glass wool or filter pa
45、per to remove insoluble particlesif present.6.2 For Methods C, D, E, and F, dissolve 68.72 g of reagentgrade ferric chloride, FeCl36H2O in 600 mL of reagent waterand add 16 mL of reagent grade concentrated (36.538.0 %)hydrochloric acid (HCl). This will produce a solution contain-ing about 6 % FeCl b
46、y mass and 1 % HCl resulting in a pHcontrolled environment over the test temperatures (9).7. Test Specimens7.1 A test specimen 25 by 50 mm (1 by 2 in.) is recom-mended as a standard size, although various shapes and sizescan be tested by this method. All specimens in a test seriesshould have the sam
47、e dimensions when comparisons are to bemade. Unless end-grain pitting is an integral part of theevaluation, the proportion of end-grain surface to specimensurface should be kept as small as possible given the limita-tions of specimen sizes because of the susceptibility ofend-grain surfaces to pittin
48、g.NOTE 8The thickness of the specimen in Method B can influence thetightness of the crevice and the test results.NOTE 9End-grain attack in Methods C, D, E, and F may not be asprevalent in a test in which low test temperatures are anticipated.7.2 When specimens are cut by shearing, the deformedmateri
49、al should be removed by machining or grinding prior totesting unless the corrosion resistance of the sheared edges isbeing evaluated. It is good practice to remove deformed edgesto the thickness of the material.7.3 For Methods D and F, a sufficient hole should be drilledand chamfered in the center of the specimen to accommodatethe bolt and insulating sleeve used to attach the crevice device.7.4 All surfaces of the specimen should be polished to auniform finish. A120-grit abrasive paper has been found toprovide a satisfactory standard finish. Wet poli
