1、Designation: B946 11 (Reapproved 2016)Standard Test Method forSurface Finish of Powder Metallurgy (PM) Products1This standard is issued under the fixed designation B946; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast 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 test method covers measuring the surface finish ofpowder metallurgy (PM) products at all stages of manufactur-ing
3、from green compact to fully hardened finished component.1.2 This test method provides the definition and schematicof some common surface finish parameters (Ra,Rt, and RzISO)1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconver
4、sions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport 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
5、 and to determine theapplicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 MPIF Standard:2MPIF Standard 58 Method for Determination of SurfaceFinish of Powder
6、Metallurgy Products3. Significance and Use3.1 The surface finish of a component may be critical forcertain applications, affecting properties such as wearresistance, fatigue strength, and coefficient of friction.3.2 Surface finish may also be critical for componentassembly or system performance. Dim
7、ensional fit and matingsurface interaction may require certain surface finish require-ments to meet performance specifications.4. Interferences4.1 Because many conventional PM materials contain openporosity at the surface, special consideration should be takenwhen measuring surface finish.4.2 The us
8、e of a conical point stylus may result in inaccurateor inconsistent surface finish results because the sharper pointof the stylus may drop into open porosity on the surface of thecomponent.4.3 A chisel point stylus may be used for better accuracyand consistency.4.4 Because the direction of pressing
9、may cause direction-ality in surface finish values, the direction of measurementshould be specified and reported.5. Apparatus5.1 Surface Finish Measuring Instrument.5.2 StylusChisel point, 0.050 in. (1.27 mm) length and0.0004 in. 6 30 % (0.010 mm 6 30 %) tip radius as shown inFig. 1. To limit the po
10、ssibility of the stylus dropping into opensurface porosity, a chisel point stylus is recommended. If acone stylus is used, filtering software shall also be used toremove the influence of open surface porosity.6. Sampling, Test Specimens, and Test Units6.1 The test surface shall be clean and free of
11、any oil, dirt,debris, or foreign material.6.2 Sufficient surface area shall be available to permitmultiple traverses by the measuring instrument.6.3 The test surface shall be flat over a sufficient length (inaccordance with instrument instructions) to allow propermovement of the stylus.7. Procedure7
12、.1 The PM parts manufacturer and purchaser shall agree onthe desired location and direction for surface finish measure-ment.7.2 Place the surface finish instrument in a position suitablefor measuring the test sample.7.3 Zero and verify the instrument over the surface finishrange expected for the tes
13、t sample.1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.05 on Structural Parts.Current edition approved April 1, 2016. Published April 2016. Originallyapproved in 2006. Last previous ed
14、ition approved in 2011 as B946 11. DOI:10.1520/B0946-11R16.2Available from Metal Powder Industries Federation (MPIF), 105 College Rd.East, Princeton, NJ 08540, http:/www.mpif.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17.4 Pla
15、ce the test sample under the stylus and then lower thestylus to the measuring position in accordance with theinstrument instructions.7.5 Measure the surface finish of the test surface. A mini-mum of three traverses at different locations is recommended.8. Report8.1 Report the surface finish to the n
16、earest whole number inmicroinches (micrometres). Unless otherwise indicated, thesurface finish shall be Ra(average surface roughness) (see Fig.2). Depending on the type of instrument being used, othersurface finish measures may also be reported.NOTE 1Rtis the maximum peak-to-valley height over the t
17、estedlength (absolute value between the highest and lowest peaks) as shown inFig. 3. Rzis the ten-point height or the absolute value of the five highestpeaks and five lowest valleys over the evaluation length as shown in Fig.4. Rzis also known as the ISO ten-point height parameter.8.2 If it has been
18、 specified, report the direction of measure-ment with respect to the pressing direction.9. Precision and BiasThe Precision for this standard was developed by the MetalPowder Industries Federation (MPIF) and is used herein withtheir permission.9.1 PrecisionThe precision of this test has been deter-mi
19、ned from an interlaboratory study performed in 2007 inwhich 11 Metal Powder Industries Federation laboratoriesparticipated.9.1.1 The repeatability (r) and reproducibility (R) measure-ments listed in Table 1 were determined according to PracticeE691.9.1.2 FLC2-4808 sinter-hardened transverse rupture
20、testspecimens with a sintered density of 6.94 g/cm3 and anapparent hardness of 45 HRC were used in the study. Eachlaboratory received a single TRS sample from this batch.9.1.3 On the basis of test error alone, the difference inabsolute value of two test results obtained in the samelaboratory will be
21、 expected to exceed (r) only 5% of the time.If such a difference is found to be larger than (r), there is reasonto question one or both results. Similarly, the difference in twotest results obtained in different laboratories will be expected toexceed (R) only 5% of the time. If the difference is fou
22、nd to belarger than (R), there is reason to question one or bothmeasurements.9.1.4 The analysis is based on three measurements persurface using a length of travel that varied from 0.098 inch(2.49 mm) to 0.5 inch (12.7 mm). Some laboratories used therecommended chisel stylus, others used the conventi
23、onal fullradius stylus point and one laboratory provided data using bothtypes of stylus.TABLE 1 Precision of Surface Finish Measurements on Sinter-Hardened FLC2-4808 TRS SpecimensSurfaceTestedType of Stylus SurfaceFinishrRmicroinch (micrometres)Punch Face Chisel 66 (1.65) 8 (0.20) 19 (0.48)Die Face
24、Chisel 26 (0.65) 29 (0.73) 40 (1.00)Punch Face Spherical 70 (1.75) 38 (0.95) 56 (1.40)Die Face Spherical 36 (0.90) 14 (0.35) 52 (1.30)9.2 BiasNo information can be presented on the bias ofthe procedure in Test Method B946 for measuring surfacefinish because no material having an accepted reference v
25、alueis available.10. Keywords10.1 PM; powder metallurgy; powder metallurgy parts;stylus; surface finish; surface roughnessNote 1The stylus is chisel shaped and has a standard radius on the edge andis 0.050 in. (1.27 mm) wide so that it will not drop into the porosity of the P/Msurface and give a fal
26、se reading by measuring the cavities.FIG. 1 Chisel Stylus for Surface Finish MeasurementNote 2The arithmetic average value of filtered roughness profile determinedfrom deviations about the centerline within the evaluation length lm.FIG. 2 RaArithmetic Mean Roughness ValueNote 3The maximum peak-to-va
27、lley height of the filtered profile over theevaluation length lm, irrespective of the sampling lengths le.FIG. 3 RtMaximum Peak-to-Valley HeightB946 11 (2016)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this stand
28、ard. 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 responsible technical committee and must be review
29、ed 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 consideration at a meeting of theresponsible
30、 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 Barr Harbor Drive, PO Box C700, West Cons
31、hohocken, 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). Permission rights to
32、photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 4The average height difference between the five highest peaks and five lowest valleys contained within a chosen evaluation length.FIG. 4 RzISOTen-Point HeightB946 11 (2016)3
