1、Designation: B 895 05Standard Test Methods forEvaluating the Corrosion Resistance of Stainless SteelPowder Metallurgy (P/M) Parts/Specimens by Immersion in aSodium Chloride Solution1This standard is issued under the fixed designation B 895; the number immediately following the designation indicates
2、the 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover a procedure for evalua
3、ting theability of sintered P/M stainless steel parts/specimens to resistcorrosion when immersed in a sodium chloride (NaCl) solu-tion.1.2 Corrosion resistance is evaluated by one of two meth-ods. In Method 1, the stainless steel parts/specimens areexamined periodically and the time to the first app
4、earance ofstaining or rust is used to indicate the end point. In Method 2,continued exposure to the sodium chloride solution is used tomonitor the extent of corrosion as a function of time.1.3 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the re
5、sponsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A 380 Practice for Cleaning, Descaling, and Passivation ofStainless Steel Parts, Equipment, an
6、d SystemsB 243 Terminology of Powder MetallurgyB 528 Test Method for Transverse Rupture Strength ofSintered Metal Powder SpecimensD 610 Test Method for Evaluating Degree of Rusting onPainted Steel SurfacesD 1193 Specification for Reagent WaterG1 Practice for Preparing, Cleaning and Evaluating Corro-
7、sion Test SpecimensG48 Test Method for Pitting and Crevice Corrosion Resis-tance of Stainless Steels and Related Alloys By the Use ofFerric Chloride Solution3. Terminology3.1 DefinitionsUseful definitions of terms for metal pow-ders and powder metallurgy are found in Terminology B 243.4. Summary of
8、Test Method4.1 Method 1 is recommended for evaluating the corrosionresistance of stainless steel powder metallurgy parts/specimensand to verify that proper materials and processing conditionswere used.4.1.1 In this method, parts/specimens are immersed in 5 %(by mass) NaCl solution and examined perio
9、dically until thefirst appearance of staining or rust. A part or specimen isconsidered to have reached the end point when the first sign ofcorrosion occurs.4.2 Method 2 is recommended for evaluating the processingvariables used in producing parts/specimens.4.2.1 In this method, parts/specimens are e
10、xposed further tothe NaCL solution and periodically rated as either A, B, C, orD (A-no corrosion; D-high or extreme corrosion) by compari-son with Fig. 1, a photograph of corroded specimens whichserves as a standard. Additional examples of quantitativeratings may be found in Test Method D 610. Metho
11、d 2 hasbeen found useful in alloy screening and process optimizationstudies.5. Significance and Use5.1 The ability of sintered powder metallurgy stainless steelparts/specimens to resist corrosion when immersed in sodiumchloride solution is important to their end use. Causes ofunacceptable corrosion
12、may be incorrect alloy, contaminationof the parts by iron or some other corrosion-promoting materialor improper sintering of the parts (for example, undesirablecarbide and nitride formations caused by poor lubricant burnoffor improper sintering atmosphere).1These test methods are under the jurisdict
13、ion of Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.05 on Structural Parts.Current edition approved March 1, 2005. Published March 2005. Originallyapproved in 1999. Last previous edition approved in 1999 as B 895 99.2For referenced AST
14、M 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 standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho
15、cken, PA 19428-2959, United States.5.2 This standard may be part of a purchase agreementbetween the P/M parts producer (seller) and the user of theparts (purchaser) (Method 1). It may also be used to optimizepart or specimen production parameters (Method 2).6. Apparatus6.1 Sealable Glass or Plastic
16、Jars, of suitable capacity forspecimens to be completely covered by the NaCl solution.6.2 Glass Beads (4 mm is recommended).6.3 Glass Stirring Rods.6.4 Tongs (Stainless steel or plastic, nonmetallic plated).7. Reagents7.1 A sodium chloride solution consisting of 5 6 0.1 % (bymass) NaCl shall be prep
17、ared using distilled or deionized waterconforming to Specification D 1193 (Type 4) and ACS reagentgrade NaCl solution. The 5 % NaCl solution shall be preparedno less than 16 h before beginning the corrosion testing.7.2 Concentrated HCl.7.3 Distilled or deionized water.8. Test Specimen8.1 Usually tes
18、t parts are sintered parts, but they may also bestandard transverse rupture bars as defined in Test MethodB 528. A minimum of five parts/specimens shall be used foreach test.8.1.1 The density of the parts or specimens as well as anypost sintering treatments, (that is, coining, repressing, machin-ing
19、, etc.) shall be stated. Parts or specimens shall be free of oil,dirt, grease and fingerprints. If they have been cleaned, thecleaning method shall be stated. Refer to Practices A 380 andG1for recommended cleaning practices.8.1.2 The use of tongs or gloves, or both, to preventcontamination in handli
20、ng is suggested.9. Preparation of Apparatus9.1 Soak previously used jars and glass beads in concen-trated HCl for at least 12 h to remove rust stains; rinse withdistilled or deionized water, then rinse again and allow to dry.9.1.1 Place the glass beads in the bottom of the beaker. Usea sufficient nu
21、mber of beads to keep the test specimen off thebottom of the jar.10. Procedure10.1 Method 1:10.1.1 Place one part or specimen per jar on top of the glassbeads. Add the NaCl solution to each jar so that the volume ofsolution, in millilitres, is at least five times the mass of thespecimen in grams. Th
22、e distance from the surface of thepart/specimen to the top of the solution should be at least 25mm. The ratio of the volume of air to the volume of solution ina jar is recommended to be about 1:2 to 1:3. Remove airbubbles attached to the specimen surface and glass beads byFIG. 1 Examples of Ratings
23、for Various Amounts of Rust or Stain (Immersion in Aqueous Solution of 5 % NaCl)B895052swirling the solution or moving the specimen with a glassstirring rod. Close the jars. Record the date and the time of thestart of the test. Store the immersed test specimens at atemperature of 21 to 24C.10.1.2 Ex
24、amine the parts/specimens after12 ,1,2,4,and8h and at 24 h intervals from the onset of the test. Thereafter, theinterval may be lengthened as time progresses until the firstappearance of rust or stain. The corrosion life of a part orspecimen is the time of the previous examination, that is, thelast
25、examination taken before the observation of stain or rust.Do not include corrosion which appears at the interfacebetween a part/specimen and the glass beads. This is consid-ered to be crevice corrosion and may be evaluated by TestMethod G 48.10.2 Method 2:10.2.1 Method 2 follows the procedure of Met
26、hod 1 through10.1.1. It continues with periodic examination as in 10.1.2,except that testing continues beyond the first appearance ofstain or rust. In Method 2, for each examination, the parts/specimens are ranked for the degree of staining or corrosionaccording to the following:AThe part/specimen i
27、s free from stain or rust.BThe first sign of stain or rust appears or up to 1 % ofsurface is covered by stain or rust.CMore than 1 and up to 25 % of surface is covered bystain or rust.DMore than 25 % of surface is covered by stain or rust.10.2.1.1 Examples of ratings exhibiting these conditions ares
28、hown in Fig. 1.10.2.1.2 Do not include corrosion which appears at theinterface between the test specimens and the glass beads. Thisis considered to be crevice corrosion and is not the subject ofthis test method. As a part/specimen shows increasing amountsof rust, it may become necessary to use a pai
29、r of tongs toremove it from the solution so as to distinguish between looseand adherent rust. Rinsing should not be used because looserust may be washed off.10.2.2 Record the results of the timed observation at theintervals used. Table 1 shows a typical example of a datacollection table.10.2.3 Plot
30、the percent of parts/specimens having an A, B,or C class rating for suitable time intervals on a logarithmictime scale.10.2.4 Draw curves to fit the data. A typical plot is shown inFig. 2.11. Report11.1 Method 1:11.1.1 Report the individual corrosion lives in hours asdetermined in 10.1.2 and calcula
31、te the arithmetic average.Acceptance criteria shall be mutually agreed upon betweenpurchaser and seller.11.1.2 Density of parts/specimens as well as any post-sintering treatments and cleaning methods (if cleaned) shall berecorded.11.2 Method 2:11.2.1 Report the time when 50 % of the parts/specimensh
32、ave an A, B, or C class rating.11.2.2 Photographs of tested parts, indicating the test con-ditions and the number of hours tested shall be provided at thecustomers request.11.2.3 Density of parts or specimens as well as any post-sintering treatments and cleaning methods (if cleaned) shall berecorded
33、.12. Precision and Bias12.1 No repeatability and reproducibility data or informa-tion on any bias inherent in these test methods are available atthis time.13. Keywords13.1 corrosion; powder metallurgy (P/M) parts; stainlesssteelTABLE 1 Example of Corrosion Rating Chart for a Set of Ten Replicate Spe
34、cimens of Sintered 316L Stainless SteelASpecimen Hours submersed in 5 % aq. NaCl# 0.5 1 2 4 8 24 31 50 74 104 168 240 336 496 696 984 1368 1804 22821 AAAAAAA A BBB BCCCCDDD2 AA BBCCCD3 AAAAAAA B BBBCCCDDDDD4 A A B BCCCCC5 AAAAAAA BB C6 A A B BCCCCCD7 AAAAAAB B BBB CCCCCD8 A B CCDDDD9 AAAAAA A BBB BC
35、CCCD10 A AB B CCCCCD% Holding 8A Rating100 100 100 100 100 100 90 70 50 10 0% Holding 8B Rating100 90 60 10 0% Holding 8C Rating100 90 80 70 40 10ASee Section 10.1.1 for definition of ratings.B895053ASTM International takes no position respecting the validity of any patent rights asserted in connect
36、ion with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsibl
37、e technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful cons
38、ideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have 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 B
39、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple 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).FIG. 2 Plot of Percentage of Replicate Specimens with a Given Rating Versus Immersion TimeB895054
