1、Designation: G157 98 (Reapproved 2013)Standard Guide forEvaluating Corrosion Properties of Wrought Iron- andNickel-Based Corrosion Resistant Alloys for ChemicalProcess Industries1This standard is issued under the fixed designation G157; the number immediately following the designation indicates the
2、year oforiginal adoption or, in the case of revision, the year 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 guide covers an evaluation approach that is de-
3、signed to provide information on the corrosion properties ofwrought iron- and nickel-based alloys for the chemical processindustries. This guide incorporates test conditions for generalcorrosion measurements in a variety of environments, crevicecorrosion resistance in chloride environments, and stre
4、ss cor-rosion cracking resistance in chloride environments.1.2 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is therespo
5、nsibility of the user of this standard to establish appro-priate safety and health practices and to determine theapplicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterG1 Practice for Preparing, Cleaning, and Evaluating Co
6、rro-sion Test SpecimensG15 Terminology Relating to Corrosion and Corrosion Test-ing (Withdrawn 2010)3G30 Practice for Making and Using U-Bend Stress-Corrosion Test SpecimensG36 Practice for Evaluating Stress-Corrosion-Cracking Re-sistance of Metals and Alloys in a Boiling MagnesiumChloride SolutionG
7、46 Guide for Examination and Evaluation of Pitting Cor-rosionG48 Test Methods for Pitting and Crevice Corrosion Resis-tance of Stainless Steels and Related Alloys by Use ofFerric Chloride SolutionG123 Test Method for Evaluating Stress-Corrosion Crackingof Stainless Alloys with Different Nickel Conte
8、nt inBoiling Acidified Sodium Chloride Solution3. Terminology3.1 Terms such as crevice corrosion, stress corrosioncracking, and corrosion rate are defined in Terminology G15.4. Significance and Use4.1 This guide is intended to provide a series of evaluationsthat will assist engineers dealing with ch
9、emical environmentsin selecting appropriate alloys (1-3). In chemical environments,an important issue for determining general corrosion resistanceis the temperature at which an alloy transitions from corrosionat a low rate to corrosion at a much higher rate. Otherimportant concerns include the tende
10、ncy towards crevicecorrosion and stress corrosion cracking resistance, especially inhot chloride-containing aqueous environments.4.2 This guide is also intended for alloy developers to assistthem in choosing environments and test methods that are ofparticular interest to the chemical process industr
11、ies.4.3 The use of this approach will allow direct comparisonsto be made among alloys from various suppliers and, thereby,to assist engineers in selecting the most appropriate materialsfor further testing to determine suitability in their application.5. General Corrosion Resistance5.1 The general co
12、rrosion resistance of nickel- and iron-based alloys is determined in 14 test solutions at varioustemperatures to determine the lowest temperature at which thecorrosion rate exceeds 0.13 mm/y (5 mpy). The test solutionsare listed in Table 1. A suggested procedure is provided inAppendix X1. The test i
13、s run on three coupons of metal foreach environment. The tests are run for two 48-h exposureswith one specimen exposed for the total 96 h. Welded speci-mens may be used if results are required on weldments.1This guide is under the jurisdiction of ASTM Committee G01 on Corrosion ofMetals and is the d
14、irect responsibility of Subcommittee G01.05 on LaboratoryCorrosion Tests.Current edition approved May 1, 2013. Published July 2013. Originally approvedin 1998. Last previous edition approved in 2005 as G157 98 (2005). DOI:10.1520/G0157-98R13.2For referenced ASTM standards, visit the ASTM website, ww
15、w.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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 B
16、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 The corrosion rates are based on mass loss measure-ments with appropriate conversion to thickness loss as shownin Appendix X1.5.3 The results of the tests in each solution should bereported on a summary results sheet.
17、Atypical format is shownin Fig. 1 and Fig. 2.6. Six Percent Ferric Chloride Solution Critical CreviceCorrosion Temperature6.1 The crevice corrosion resistance of each alloy is to beevaluated as described in Test Methods G48, Method D. Thestandard exposure period of 72 h is to be used. Mass lossresul
18、ts are also to be obtained and reported in this environment.6.2 The results of this test are to be reported as discussed inTest Methods G48. The results should also be entered on thesummary results sheet shown in Fig. 3.7. Chloride Stress Corrosion Resistance7.1 The resistance to chloride stress cor
19、rosion cracking is animportant characteristic of alloys used in the chemical processindustries. Two environments are provided to evaluate andreport chloride stress corrosion cracking behavioracidifiedsodium chloride and magnesium chloride. The magnesiumchloride environment is highly acidic and, as a
20、 consequence,tends to cause many suitably resistant alloys to fail. Theacidified sodium chloride environment gives results closer toexperience in cooling water and process water environments.7.2 Acidified Sodium Chloride TestTest Method G123should be used to evaluate all alloys for resistance to chl
21、oridestress corrosion cracking. The specimen design suggested inTest Method G123 should be used, if possible. This design isbased on the Practice G30 U-bend and the tests should becarried out with at least triplicate specimens for a period of1000 h. The results are to be reported as described in Tes
22、tMethod G123 and entered on the summary results sheet. SeeFig. 3.7.3 Magnesium Chloride Test, OptionalAlloys that do notcrack in the acidified sodium chloride environment may beTABLE 1 Fourteen Environments for Evaluating GeneralCorrosion ResistanceCorrodent Formula Concentration, %AHydrochloric Aci
23、d HCl 0.2, 1.0, 5.0Sulfuric Acid H2SO410, 60, 96BNitric Acid HNO310, 70BPhosphoric Acid H3PO485BFormic Acid HCOOH 50Acetic Acid CH3COOH 80Sodium Hydroxide NaOH 50Hydrochloric Acid + HCl + FeCl31.0 HCl + 0.3 FeCl3CFerric ChlorideAcetic Acid + CH3COOH + (CH3CO)2O 50/50Acetic AnhydrideAAll chemicals ar
24、e ACS reagent grade mixed with Specification D1193 Type 4reagent water.BUndiluted reagent grade acid may be used.CFerric chloride concentration calculated on anhydrous basis.FIG. 1 Summary Results Form - Alloy DescriptionFIG. 2 Summary Results Form - General Corrosion ResistanceFIG. 3 Summary Result
25、s Form - Localized Corrosion Perfor-manceG157 98 (2013)2tested in a magnesium chloride test. The test environment isdescribed in Practice G36. U-bend specimens similar to thosesuggested in Test Method G123 should be used with triplicatereplication. The test should be run for 30 days or until crackin
26、gis observed. The specimens should be removed at convenientintervals not to exceed three days during exposure and exam-ined for cracking. The time to first crack is reported. Metallo-graphic sectioning is to be carried out on at least one of eachset of replicates at the end of the exposure to docume
27、nt thecrack morphology or, in the case of surviving specimens, thatno microcracks are present. The result of this test is to bereported on the summary results sheet (Fig. 3).8. Report8.1 The results of these tests are to be reported as specifiedin the test method referenced. The summary results shee
28、tsshown in Figs. 1-3 provide a convenient form to present theresults in a consistent format.9. Keywords9.1 chemical process industry; crevice corrosion; generalcorrosion; iron-base corrosion resistant alloys; nickel-basecorrosion resistant alloys; stress corrosion crackingAPPENDIX(Nonmandatory Infor
29、mation)X1. SUGGESTED LABORATORY TESTING OF IRON- AND NICKEL-BASED ALLOYS FOR CORROSION RESISTANCE INSELECTED MEDIA FOR GENERAL CORROSION PERFORMANCEX1.1 ScopeX1.1.1 This test method describes a suggested procedure forcorrosion tests to determine the relative resistance of wroughtiron- and nickel-bas
30、ed alloys to corrosion in selected media.These tests are intended to provide corrosion data suitable forpreliminary evaluation prior to testing for specific chemicalapplications.X1.1.2 Each alloy is tested in the as-manufactured condi-tion; as-welded specimens may be included. (See X1.3.10.2 forwhen
31、 only the as-welded condition need be tested.)X1.1.3 Specimen evaluation procedures provide for massloss measurements for evaluation of general corrosion and lowpower surface microscopic examination for presence of local-ized corrosion, such as pitting, stress corrosion, intergranularattack, end-gra
32、in corrosion, and preferential weld attack.X1.2 ApparatusX1.2.1 A 1000 mL Erlenmeyer flask equipped with a refluxcondenser, a sparger with a fitted glass disc for deaeratingcertain solutions, a specimen support system, and a means forcontrolling the temperature of the contents of the flask arerecomm
33、ended for all tests.X1.2.2 All components of the apparatus described in X1.2.1which are in contact with the test environment (liquid and gasphases) are to be made of glass or polytetrafluoroethylene(PTFE) or other inert nonconductive material.X1.2.3 The temperature-regulating device used for tests a
34、ttemperatures other than the boiling temperature should becapable of controlling the temperature of the contents of theflask to within 61C of the selected test temperature.X1.2.4 The specimen support system should be designed sothat the specimen is separated from the flask and its internalcomponents
35、. The specimen is to be maintained in a verticalposition, totally immersed in the test solution. One desirablesupport system is to use an individual glass cradle for eachspecimen.X1.2.5 A nitrogen sparging system, which is used for initialdeaeration in tests at temperatures below boiling and innon-o
36、xidizing solutions, should be capable of sparging nitro-gen at the rate of 100 mL/min.Adevice to prevent backflow oftest solution into the gas supply system should be included.X1.3 Test SpecimensX1.3.1 The specimens should be made from sheet, plate, orstrip produced by commercial methods.X1.3.2 Mate
37、rial from which the specimens are made shouldbe in the annealed condition, the final heat treatment beingdone after any cold rolling. Temperature of the final heattreatment and method of cooling should be reported.X1.3.3 Thickness of the sheet materials used for specimensshould be between 1.5 and 4.
38、8 mm (0.06 and 0.188 in.). Widthof the specimens should be 20 mm (0.8 in.) and the length 50mm (2.0 in.).X1.3.4 Specimens are to be cut to size by a machiningoperation. If sheared specimens are used, the sheared edges areto be removed by grinding or machining; the amount of metalremoved by machining
39、 should equal the thickness of thespecimen.X1.3.5 All specimens should be abraded to provide auniform surface finish free of scale and dirt, and to remove anysharp edges or burrs due to machining or drilling operations.The final step in this abrading operation should be done withwet No. 80 or dry No
40、. 120 grit abrasive paper. Exercise care toavoid overheating the surface. This step should be omittedwhen the intent of the test is to evaluate mill finish or othersurface conditions.X1.3.6 Specimens should be stamped with identifying let-ters and numbers, using clean, hardened steel stamps.X1.3.7 S
41、pecimens should be measured prior to test and thetotal exposed area, including edges, calculated and reported tothe closest 65 mm2(0.1 in.2).G157 98 (2013)3X1.3.8 Following the abrasive treatment, the specimensshould be cleaned with a magnesium oxide paste or detergentsolution to remove any residual
42、 dirt or grease, rinsed in water,and dipped in acetone and air dried.X1.3.9 The dried specimens should be weighed to anaccuracy of at least 60.2 mg. Weighed specimens should bestored in a desiccator for at least 24 h before use.X1.3.10 Two kinds of specimens may be used: (1)asmanufactured specimens
43、and (2) as-welded specimens.X1.3.10.1 As-Manufactured SpecimensThese specimensshould be prepared according to the procedure described inX1.3.1-X1.3.9.X1.3.10.2 As-Welded SpecimensThe principal reason forusing these specimens is to evaluate the corrosion resistance ofthe weld deposit. However, where
44、the corrosion resistance ofthe weld deposit is equal to, or better than, that of the parentmetal, a welded specimen can be used in lieu of the as-manufactured specimen and thus avoid running an additionaltest. The welded specimens should be prepared from materialdescribed in X1.3.1 and X1.3.2. The m
45、inimum thickness ofmaterial for these specimens should be 3.0 mm (0.12 in.). Theweld should be made so that it will be in the center of thespecimen and be parallel to the long direction of the specimen.The weld should be a gas-tungsten arc (GTAW) with fillermetal. The filler metal and welding proced
46、ure should corre-spond to that recommended by the manufacturer for fabricationof process equipment. The weld bead should be ground ormachined flush with the base metal.The final preparation of thespecimen should be as specified in X1.3.3-X1.3.9. Thereshould be no post-weld heat treatment.X1.4 Test S
47、olutionsX1.4.1 Test solution should be prepared accurately fromreagent grade chemicals conforming to the Specifications ofthe Committee onAnalytical Reagents of theAmerican Chemi-cal Society,4and Specification D1193 Type IV reagent water.X1.4.2 The compositions of the various test solutions aregiven
48、 in Table 1.X1.4.3 The sparging gas, employed to deaerate non-oxidizing solutions to be used in tests at temperatures belowthe boiling point, should be nitrogen with a purity of at least99.9 % and with an oxygen content of less than 0.02 %.X1.4.4 Procedure for Preparing Solutions:X1.4.4.1 Hydrochlor
49、ic Acid SolutionUse hydrochloricacid 36.5 to 38 %, specific gravity 1.185 to 1.192. Prepare 1200mL of each solution using the volumes shown as follows:Desired % mL Concentrated HCl mL Reagent H2O0.2 5.4 11971.0 27.2 11845.0 139 1125Add water to a 1.5 L beaker, then carefully and slowly addthe reagent acid to the beaker while stirring the mixture. Whencool, measure 600 mL into each flask for the test.X1.4.4.2 Sulfuric Acid SolutionUse sulfuric acid 95 to98 %, specific gravity 1.84 min. Prepare 800 mL of eachsolution using volumes shown as follows:Desired % mL Concentrated A
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