1、Designation: G35 98 (Reapproved 2015)Standard Practice forDetermining the Susceptibility of Stainless Steels andRelated Nickel-Chromium-Iron Alloys to Stress-CorrosionCracking in Polythionic Acids1This standard is issued under the fixed designation G35; the number immediately following the designati
2、on indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers procedures for pre
3、paring and con-ducting the polythionic acid test at room temperature, 22 to25C (72 to 77F), to determine the relative susceptibility ofstainless steels or other related materials (nickel-chromiumironalloys) to intergranular stress corrosion cracking.1.2 This practice can be used to evaluate stainles
4、s steels orother materials in the “as received” condition or after beingsubjected to high-temperature service, 482 to 815C (900 to1500F), for prolonged periods of time.1.3 This practice can be applied to wrought products,castings, and weld metal of stainless steels or other relatedmaterials to be us
5、ed in environments containing sulfur orsulfides. Other materials capable of being sensitized can alsobe tested in accordance with this test.1.4 This practice may be used with a variety of stresscorrosion test specimens, surface finishes, and methods ofapplying stress.1.5 This standard does not purpo
6、rt 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 more specificprecautionary statements, see
7、 Section 7.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterG1 Practice for Preparing, Cleaning, and Evaluating Corro-sion Test SpecimensG15 Terminology Relating to Corrosion and Corrosion Test-ing (Withdrawn 2010)3G30 Practice for Making and Using U-Bend Stress-Corros
8、ion Test Specimens3. Summary of Practice3.1 The stressed specimens are placed in the container alongwith a sensitized and stressedAISI Type 302 (UNS S30200) orType 304 (UNS S30400) stainless steel control specimen. Asufficient amount of the previously prepared polythionic acidsolution is added to th
9、e container to immerse the test speci-mens. A cover is placed on the container and the test is carriedout at room temperature.4. Significance and Use4.1 This environment provides a way of evaluating theresistance of stainless steels and related alloys to intergranularstress corrosion cracking. Failu
10、re is accelerated by the presenceof increasing amounts of intergranular precipitate. Results forthe polythionic acid test have not been correlated exactly withthose of intergranular corrosion tests.Also, this test may not berelevant to stress corrosion cracking in chlorides or causticenvironments.4.
11、2 The polythionic acid environment may produce areas ofshallow intergranular attack in addition to the more localizedand deeper cracking mode of attack. Examination of failedspecimens is necessary to confirm that failure occurred bycracking rather than mechanical failure of reduced sections.5. Appar
12、atus5.1 Any suitable glass or other transparent, inert containercan be used to contain the acid solution and stressed specimensduring the period of test at room temperature, 22 to 25C (72to 77F). The container should be fitted with a removable topto reduce evaporation and to allow access to the stre
13、ssedspecimen (or specimens) for the periodic inspection.1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of Subcommittee G01.06 on Environmen-tally Assisted Cracking.Current edition approved Nov. 1, 2015. Published November 2015. O
14、riginallyapproved in 1988. Last previous edition approved in 2010 as G3598(2010). DOI:10.1520/G0035-98R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standa
15、rds Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Reagents6.1 Purity of ReagentsThe polythionic acid sol
16、ution shallbe prepared using reagent grade sulfurous acid and technicalgrade hydrogen sulfide; or, distilled water, commercial gradesulfur dioxide, and technical grade hydrogen sulfide.6.2 Purity of WaterReagent water Type IV (SpecificationD1193) shall be used to prepare the test solutions.6.3 Wacke
17、nroders or Polythionic Acid Solution (1)4Aslow current of hydrogen sulfide is passed for an hour througha fritted glass tube into a flask containing chilled (0C, 32F)6 % sulfurous acid, after which the liquid is kept in thestoppered flask for 48 h at room temperature. This operation isrepeated until
18、 the liquid no longer gives off the odor of sulfurdioxide after standing at room temperature for a few hours.Note safety precautions in Section 7.6.3.1 In an alternative method (2), the polythionic acidsolution is prepared by passing a slow current of sulfur dioxidegas through a fritted glass bubble
19、r submerged in a container ofdistilled water. This is continued until the solution becomessaturated and then the hydrogen sulfide gas is slowly bubbledinto the sulfurous acid solution.6.3.2 The presence of polythionic acids in the solutionprepared in accordance with 6.3 or 6.3.1 can be checked byeit
20、her of the following methods. Polarography (3) can beemployed to identify the thionic acids, or the percent of acidpresent in the solution can be determined by wet techniques(4). The simplest method of checking the solution for poly-thionic acids is to expose a stressed and sensitized sample ofAISI
21、Type 302 stainless steel. The sample should fail bycracking in less than 1 h.Alternatively, Type 304 sheet (0.07 %carbon) which has been sensitized and exposed as a U-bendshould crack in 1 h (5). Detection of cracks can be facilitatedby closing the legs of the U-bend and examining with a 20binocular
22、 microscope.7. Safety Precautions7.1 Hydrogen sulfide should be handled with extreme cau-tion. The characteristic odor of hydrogen sulfide cannot alwaysbe used as an alarm system because the olfactory nervesbecome deadened when exposed to a concentration of a fewparts per million of this gas. The ma
23、ximum allowable concen-tration in the air for an 8-h work day is 10 ppm, which is wellabove the level detectable by smell. Exposure to high concen-trations of hydrogen sulfide can be fatal. For additionalinformation on the toxicity of hydrogen sulfide, consult Ref(6).7.2 Normal laboratory precaution
24、s should be observed whenhandling the sulfurous or polythionic acid solutions. Hydrogensulfide should only be used in a hood observing the aboveprecautions.8. Test Specimens8.1 Any type of stress corrosion test specimen can be usedwith this test solution. For a comprehensive discussion of thevarious
25、 types of test specimens available, see Ref (7), as wellas Practices G1 and G30, and Terminology G15.8.2 The AISI Type 302 control specimens should be sensi-tized by heating in a furnace for 4 h at 650C (1200F) andthen allowing to air cool. TheAISI Type 304 control specimensshould be sensitized by h
26、eating in a furnace for2hat677C(1250F) and then allowing to air cool.9. Procedure9.1 Prepare the polythionic acid test solution as described in6.3 and 6.3.1.9.2 Prior to usage, filter the acid solution to remove theexcess sulfur and test for the presence of polythionic acids. Thesimplest method of t
27、esting for the acid is to expose a stressedspecimen of sensitized AISI Type 302 or Type 304 stainlesssteel. The specimen should fail by cracking in less than 1 h.9.3 Place the stressed specimens in the container along withthe sensitized and stressedAISI Type 302 or Type 304 stainlesssteel control sa
28、mple. Add a sufficient amount of polythionicacid solution to the container to immerse the test specimens.Close the container and carry out the test at room temperature.Record starting time for the test.10. Report10.1 Record starting time, type of specimen, stress, and typeof exposure. A distinction
29、must be made in the type ofexposure; that is, complete immersion, vapor phase exposure,or a combination of immersion and vapor phase. The timerequired to initiate cracks, the rate of crack growth, and time tofailure may be of importance, depending upon the purpose ofthe test.10.1.1 Periodic removal
30、of specimens from the solutionmay be necessary to determine the time when cracks firstappear and the rate of crack propagation. Microscopicalexamination of polished surfaces is required to detect crackinitiation. All stressed surfaces should be examined at magni-fications up to 20 at the completion
31、of this test. Metallo-graphic examination of exposed surfaces and of polished andetched cross sections at higher magnifications are necessary toestablish the type of cracking.10.1.2 Ruptured specimens should also be examined forevidence of mechanical failure resulting from the action ofapplied stres
32、s on specimens whose cross sections have beenreduced by general or pitting corrosion or both. Such failuresusually show evidence of ductility. Duplicate tests with thickerspecimens should be made in cases of doubt.11. Keywords11.1 accelerated test; nickel-chromium-iron alloys; poly-thionic acids; st
33、ainless steels; stress-corrosion cracking4The boldface numbers in parentheses refer to a list of references at the end ofthis standard.G35 98 (2015)2REFERENCES(1) Debus, H., “Chemical Investigation of Wackenroders Solution,”Journal of the Chemical Society, London, Transactions, Vol 53, 1888,p. 278 (
34、paper XXV).(2) Samans, C. H., “Stress Corrosion Cracking Susceptibility of StainlessSteels and Nickel-Base Alloys in Polythionic Acids and Acid CopperSulfate Solution,” Corrosion, Vol 20, August 1964, pp. 256t262t.(3) Murayama, T., “Polarography of Polythionates,” Journal of ChemicalSociety of Japan
35、, Pure Chemistry Section, Vol 74, No. 5, 1953, pp.349352.(4) Jay, P. R., “Determination of Polythionic Acids,” AnalyticalChemistry, Vol 25, No. 2, 1953, pp. 288290.(5) Crum, J. R., Adkins, M. E., and Lipscomb, W. G., “Performance ofHigh Nickel Alloys in Refinery and Petrochemical Environments,”Mater
36、ials Performance, Vol. 25, No. 7, July, 1986, pp. 2733.(6) Chemical Safety Data Sheet SD-36, Manufacturing ChemistsAssociation, 1825 Connecticut Ave., N.W., Washington, DC 20009.(7) “Stress Corrosion Testing Methods,” Stress Corrosion Testing,ASTMSTP 425, ASTM Testing Mats. (Out of print. Send order
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40、ve not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multipl
41、e copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 98 (2015)3
