1、Designation: B895 05 (Reapproved 2010)1Standard Test Methods forEvaluating the Corrosion Resistance of Stainless SteelPowder Metallurgy (PM) Parts/Specimens by Immersion in aSodium Chloride Solution1This standard is issued under the fixed designation B895; the number immediately following the design
2、ation indicates 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 () indicates an editorial change since the last revision or reapproval.1NOTEUpdated abbreviation for powder metallu
3、rgy throughout editorially in June 2010.1. Scope1.1 These test methods cover a procedure for evaluating theability of sintered PM 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 Me
4、thod 1, the stainless steel parts/specimens areexamined periodically and the time to the first appearance 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 stan
5、dard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof 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 Standar
6、ds:2A380 Practice for Cleaning, Descaling, and Passivation ofStainless Steel Parts, Equipment, and SystemsB243 Terminology of Powder MetallurgyB528 Test Method for Transverse Rupture Strength ofMetal Powder SpecimensD610 Practice for Evaluating Degree of Rusting on PaintedSteel SurfacesD1193 Specifi
7、cation for Reagent WaterG1 Practice for Preparing, Cleaning, and Evaluating Corro-sion Test SpecimensG48 Test Methods for Pitting and Crevice Corrosion Resis-tance of Stainless Steels and Related Alloys by Use ofFerric Chloride Solution3. Terminology3.1 DefinitionsUseful definitions of terms for met
8、al pow-ders and powder metallurgy are found in Terminology B243.4. Summary of 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,
9、 parts/specimens are immersed in 5 %(by mass) NaCl solution and examined periodically 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
10、 used in producing parts/specimens.4.2.1 In this method, parts/specimens are exposed 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. Addit
11、ional examples of quantitativeratings may be found in Test Method D610. Method 2 has beenfound 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 sodiumchlo
12、ride solution is important to their end use. Causes ofunacceptable corrosion may be incorrect alloy, contaminationof the parts by iron or some other corrosion-promoting material1These test methods are under the jurisdiction of Committee B09 on MetalPowders and Metal Powder Products and is the direct
13、 responsibility of Subcom-mittee B09.05 on Structural Parts.Current edition approved May 1, 2010. Published June 2010. Originallyapproved in 1999. Last previous edition approved in 2005 as B895 05. DOI:10.1520/B0895-05R10E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcon
14、tact 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 Conshohocken, PA 19428-2959, United States.or improper sintering
15、 of the parts (for example, undesirablecarbide and nitride formations caused by poor lubricant burnoffor improper sintering atmosphere).5.2 This standard may be part of a purchase agreementbetween the PM parts producer (seller) and the user of the parts(purchaser) (Method 1). It may also be used to
16、optimize part orspecimen production parameters (Method 2).6. Apparatus6.1 Sealable Glass or Plastic 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 p
17、lated).7. Reagents7.1 A sodium chloride solution consisting of 5 6 0.1 % (bymass) NaCl shall be prepared using distilled or deionized waterconforming to Specification D1193 (Type 4) and ACS reagentgrade NaCl solution. The 5 % NaCl solution shall be preparedno less than 16 h before beginning the corr
18、osion testing.7.2 Concentrated HCl.7.3 Distilled or deionized water.8. Test Specimen8.1 Usually test parts are sintered parts, but they may also bestandard transverse rupture bars as defined in Test MethodB528. A minimum of five parts/specimens shall be used foreach test.8.1.1 The density of the par
19、ts or specimens as well as anypost sintering treatments, (that is, coining, repressing, machin-ing, 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 A380 andG1 for recommend
20、ed cleaning practices.8.1.2 The use of tongs or gloves, or both, to preventcontamination in handling 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
21、again and allow to dry.9.1.1 Place the glass beads in the bottom of the beaker. Usea sufficient number of beads to keep the test specimen off thebottom of the jar.FIG. 1 Examples of Ratings for Various Amounts of Rust or Stain (Immersion in Aqueous Solution of 5 % NaCl)B895 05 (2010)1210. Procedure1
22、0.1 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. The distance from the surface of thepart/specimen to the top of the solution shou
23、ld 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 byswirling the solution or moving the specimen with a glassstirring rod. Close the jars. Record the date and
24、 the time of thestart of the test. Store the immersed test specimens at atemperature of 21 to 24 C.10.1.2 Examine 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
25、or stain. The corrosion life of a part orspecimen is the time of the previous examination, that is, thelast 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
26、corrosion and may be evaluated by TestMethod G48.10.2 Method 2:10.2.1 Method 2 follows the procedure of Method 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/
27、specimens are ranked for the degree of staining or corrosionaccording to the following:AThe part/specimen is free from stain or rust.BThe first sign of stain or rust appears or up to1%ofsurface is covered by stain or rust.CMore than 1 and up to 25 % of surface is covered bystain or rust.DMore than 2
28、5 % of surface is covered by stain or rust.10.2.1.1 Examples of ratings exhibiting these conditions areshown 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 ofth
29、is test method. As a part/specimen shows increasing amountsof rust, it may become necessary to use a pair 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
30、observation at theintervals used. Table 1 shows a typical example of a datacollection table.10.2.3 Plot 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. Repo
31、rt11.1 Method 1:11.1.1 Report the individual corrosion lives in hours asdetermined in 10.1.2 and calculate 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 meth
32、ods (if cleaned) shall berecorded.11.2 Method 2:11.2.1 Report the time when 50 % of the parts/specimenshave 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
33、or specimens as well as any post-sintering treatments and cleaning methods (if cleaned) shall berecorded.TABLE 1 Example of Corrosion Rating Chart for a Set of Ten Replicate Specimens 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 4
34、96 696 984 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 BCCCCD10 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 R
35、ating100 90 80 70 40 10ASee Section 10.1.1 for definition of ratings.B895 05 (2010)1312. 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 (PM) parts; sta
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39、STM 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 multiple copies) of this standard may be obtained by contacting ASTM at the ab
40、oveaddress 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 ASTM website (www.astm.org/COPYRIGHT/).FIG. 2 Plot of Percentage of Replicate Specimens with a Given Rating Versus Immersion TimeB895 05 (2010)14
