ASTM G76-2018 Standard Test Method for Conducting Erosion Tests by Solid Particle Impingement Using Gas Jets.pdf

1、Designation: G76 13G76 18Standard Test Method forConducting Erosion Tests by Solid Particle ImpingementUsing Gas Jets1This standard is issued under the fixed designation G76; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year

2、 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 test method covers the determination of material loss by gas-entrained solid particle impingement erosion withjet

3、nozzle type erosion equipment. This test method may be used in the laboratory to measure the solid particle erosion of differentmaterials and has been used as a screening test for ranking solid particle erosion rates of materials in simulated serviceenvironments (1, 2).2 Actual erosion service invol

4、ves particle sizes, velocities, attack angles, environments, and so forth, that willvary over a wide range (3-5). Hence, any single laboratory test may not be sufficient to evaluate expected service performance.This test method describes one well characterized procedure for solid particle impingemen

5、t erosion measurement for whichinterlaboratory test results are available.1.2 UnitsThe values stated in SI units are to be regarded as standard. No other units of measurement are included in thisstandard (exceptions below).1.2.1 Exceptions: Table 1 uses HRB hardness. Footnote 7 and 11.2 use abrasive

6、 grit designations.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regul

7、atory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organi

8、zation Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot orProcessG40 Terminology Relating to Wear and Erosion2.2 American National Standard

9、:ANSI B74.10 Grading of Abrasive Microgrits41 This test method is under the jurisdiction of ASTM Committee G02 on Wear and Erosion and is the direct responsibility of Subcommittee G02.10 on Erosion by Solidsand Liquids.Current edition approved July 1, 2013Oct. 1, 2018. Published July 2013November 20

10、18. Originally approved in 1983. Last previous edition approved in 20072013 asG76G76 13.07. DOI: 10.1520/G0076-13.10.1520/G0076-18.2 The boldface numbers in parentheses refer to a list of references at the end of this standard.3 For referencedASTM standards, visit theASTM website, www.astm.org, or c

11、ontactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.TABLE 1 Characteristics o

12、f Type 1020 Steel Reference MaterialAnnealed 900 s at 760C, air cooled.Hardness: HRB = 70 2.Chemical Composition:C = 0.20 0.01 wt %Mn = 0.45 0.10S = 0.03 0.01Si = 0.1 0.05P = 0.01 0.01This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of

13、what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered

14、the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:3.1.1 erosionprogressive loss of original material from a solid surface due to mechanical interaction between that surface anda fluid,

15、 a multicomponent fluid, or impinging liquid or solid particles.3.1.2 impingementa process resulting in a continuing succession of impacts between (liquid or solid) particles and a solidsurface.3.2 Definitions of Terms Specific to This Standard:3.2.1 erosion valuethe volume loss of specimen material

16、 divided by the total mass of abrasive particles that impacted thespecimen (mm3g1).3.2.2 Normalized Erosion Rateerosion value (mm3g1) of specimen material divided by erosion value (mm3g1) of referencematerial.4. Summary of Test Method4.1 This test method utilizes a repeated impact erosion approach i

17、nvolving a small nozzle delivering a stream of gas containingabrasive particles which impacts the surface of a test specimen.Astandard set of test conditions is described. However, deviationsfrom some of the standard conditions are permitted if described thoroughly. This allows for laboratory scale

18、erosion measurementsunder a range of conditions. Test methods are described for preparing the specimens, conducting the erosion exposure, andreporting the results.5. Significance and Use5.1 The significance of this test method in any overall measurements program to assess the erosion behavior of mat

19、erials willdepend on many factors concerning the conditions of service applications. The users of this test method should determine thedegree of correlation of the results obtained with those from field performance or results using other test systems and methods.This test method may be used to rank

20、the erosion resistance of materials under the specified conditions of testing.6. Apparatus6.1 The apparatus is capable of eroding material from a test specimen under well controlled exposure conditions. A schematicdrawing of the exit nozzle and the particle-gas supply system is shown in Fig. 1. Devi

21、ations from this design are permitted;however, adequate system characterization and control of critical parameters are required. Deviations in nozzle design anddimensions must be documented. Nozzle length to diameter ratio should be 25:1 or greater in order to achieve an acceptableparticle velocity

22、distribution in the stream. The recommended nozzle5 consists of a tube about 1.5 mm inner diameter, 50 mm long,manufactured from an erosion resistant material such as WC, A12O3, and so forth. Erosion of the nozzle during service shall bemonitored and shall not exceed 10 % increase in the initial dia

23、meter.5 The sole source of supply of the recommended nozzle (tungsten carbide) known to the committee at this time is Kennametal Inc., 1600 Technology Way, PO Box 231,Latrobe, PA 15650-0231. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters

24、. Your comments will receive carefulconsideration at a meeting of the responsible technical committee,1 which you may attend.where:a = gas jet nozzle,b = nozzle length,c = mixing chamber,d = abrasive hopper,e = gas source,f = test specimen,g = nozzle-to-specimen distance, and = impingement angle.FIG

25、. 1 Schematic Drawing of Solid Particle Erosion Equipmentof Test RigG76 1826.2 Necessary features of the apparatus shall include a means of controlling and adjusting the particle impact velocity, particleflux, and the specimen location and orientation relative to the impinging stream.stream (impinge

26、ment angle).6.3 Various means can be provided for introducing particles into the gas stream, including a vibrator-controlled hopper or ascrew-feed system. It is required that the system provide a uniform particle feed and that it be adjustable to accommodate desiredparticle flow values.6.4 Amethod t

27、o measure the particle velocity shall be available for use with the erosion equipment (6-9). Examples of acceptedmethods are high-speed photography (7), rotating double-disk (6),(8), and laser velocimeter (9). Particle velocity shall be measuredat the location to be occupied by the specimen and unde

28、r the conditions of the test.7. Test Materials and Sampling7.1 This test method can be used over a range of specimen sizes and configurations. One convenient specimen configurationis a rectangular strip approximately 10 by 30 by 2 mm thick. Larger specimens and other shapes can be used where necessa

29、ry, butmust be documented.7.2 The abrasive material to be used shall be uniform in essential characteristics such as particle size, moisture, chemicalcomposition, and so forth.7.3 Sampling of material for the purpose of obtaining representative test specimens shall be done in accordance with accepta

30、blestatistical practice. Practice E122 shall be consulted.8. Calibration of Apparatus8.1 Specimens fabricated from Type 1020 steel (see Table 1 and Fig. 2) equivalent to that used in the interlaboratory test series6shall be tested periodically using specified (see Section 9) 50 m A12O3 particles to

31、verify the satisfactory performance of theapparatus. It is recommended that performance be verified using this reference material every 50 tests during a measurement series,and also at the beginning of each new test series whenever the apparatus has been idle for some time. The recommendedcompositio

32、n, heat treatment, and hardness range for this steel are listed in Table 1. The use of a steel of different composition maylead to different erosion results.Aphotomicrograph of the specifiedA12O3 particles is shown in Fig. 3. The range of erosion resultsto be expected for this steel under the standa

33、rd test conditions specified in Section 9 is shown in Table 2 and is based oninterlaboratory test results.68.2 Calibration at standard test conditions is recommended even if the apparatus is operated at other test conditions.8.3 In any test program the particle velocity and particle feed rate shall

34、be measured at frequent intervals, typically every tentests, to ensure constancy of conditions.6 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:G02-1003.FIG. 2 Microstructure of 1020 Steel Reference MaterialASTM Grain Size 9G76

35、 1839. Standard Test Conditions9.1 This test method defines the following standard conditions.9.1.1 The nozzle tube shall be 1.5 mm 6 0.075 mm inner diameter at least 50 mm long.9.1.2 The test gas shall be nominally dry air. The test report shall indicate the amount of water present in the test gas,

36、 at whatpressure, and how the measurement was conducted.NOTE 1In the interlaboratory testing, one laboratory utilized cylinder-type compressed air having a water content amount described as “-50C dewpoint” by the manufacturer. Whatever gas source is used in testing, a comparable level of dryness to

37、that is recommended.9.1.3 The abrasive particles shall be nominal 50-m angular A12O3,7 equivalent to those used in the interlaboratory test series(see Fig. 3). Abrasive shall be used only once.NOTE 2Typical size distribution (determined by sedimentation): 100 % between 20 to 83 m, 50 % between 42 to

38、 57 m, 50 % coarser than 48 m.9.1.4 The abrasive particle velocity shall be 30 6 2 ms1, measured at the specimen location.At this velocity the gas flow ratewill be approximately 0.13 L/s and the system pressure will be approximately 140 kPa although the pressure will depend on thespecific system des

39、ign.9.1.5 The test time shall be 600 s to achieve steady state conditions. Longer times are permissible so long as the final erosioncrater is no deeper than 1 mm.9.1.6 The angle between the nozzle axis and the specimen surface shall be 90 6 2.9.1.7 The test temperature shall be the normal ambient va

40、lue (typically between 18C to 28C).9.1.8 The particle feed rate shall be 0.033 6 0.008 g/s. This corresponds to a particle flux at the specimen surface of about 2mgmm2s1 under standard conditions. Particle flux determination requires measurement of the eroded area on the specimen andis subject to co

41、nsiderable error.Ameasured width and depth profile of an erosion crater produced using stated conditions is shownin Fig. 4 and indicates a typical eroded width/depth relation.9.1.9 The distance from specimen surface to nozzle end shall be 10 6 1 mm.10. Optional Test Conditions10.1 When test conditio

42、ns or materials other than those given in Section 9 are used, reference to this test method shall clearlyspecify all test conditions and materials. It should be noted that other conditions, for example, larger particle velocities, mayadversely affect measurement precision.7 The sole source of supply

43、 of the aluminum oxide particlesobtained as grade 240-grit alundum powder knownaluminum oxide powderknown to the committeeat this time is Norton Co., 1 New Bond St, Worcester, MA 01606. If you are aware of alternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your

44、 comments will receive careful consideration at a meeting of the responsible technical committee,1 which you may attend.FIG. 3 Photomicrograph of 50 m A12O3 Particles Used in Interlaboratory TestingG76 18411. Test Procedure11.1 Establish and measure the particle velocity and particle flow specified.

45、Adjust equipment controls to obtain proper velocityand flow conditions before inserting test specimens. Particle flow rate values are determined by collecting (see Note 3) andsubsequently weighing the abrasive exiting from the nozzle for a measured time period.NOTE 3Particles may be collected by dir

46、ecting the flow from the nozzle into a large vented container. Care must be taken to avoid causing anysignificant back pressure on the nozzle as this will disturb the system flow conditions.11.2 Prepare the specimen surface if required to achieve uniformity and adequate finish. Grinding through a se

47、ries of abrasivepapers to 400 grit is usually adequate so long as all surface scale is removed.Asurface roughness of 1 m (40 in.) rms or smalleris recommended. Clean the specimen surface carefully (see Note 4). Weigh on an analytical balance to 60.01 mg (see Note 5).NOTE 4Important considerations in

48、 cleaning include surface oils or greases, surface rust or corrosion, adhering abrasive particles, etc.NOTE 5Erosion weight loss determinations to 60.1 mg may be sufficient for particle velocities above 70 ms1 or sufficiently long exposure timeswhich lead to weight losses greater than 10 mg.11.3 Mou

49、nt the specimen in proper location and orientation in the apparatus. Subject the specimen to particle impingement fora selected time interval, measured to an accuracy of 5 s. Remove the specimen, clean carefully (see Note 4), reweigh and calculatethe mass loss.11.4 Repeat this process utilizing a new specimen each time to determine at least four points for a total time of at least 600 sand plot those values as mass loss versus elapsed time. Suitable times would be 120, 240, 480, and 960 s for a material such asType 1020 stee