1、Designation: G 77 05e1Standard Test Method forRanking Resistance of Materials to Sliding Wear UsingBlock-on-Ring Wear Test1This standard is issued under the fixed designation G 77; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, th
2、e year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEEditorial changes were made throughout in June 2005.1. Scope1.1 This test method covers laboratory procedures for de-
3、termining the resistance of materials to sliding wear. The testutilizes a block-on-ring friction and wear testing machine torank pairs of materials according to their sliding wear charac-teristics under various conditions.1.2 An important attribute of this test is that it is veryflexible.Any materia
4、l that can be fabricated into, or applied to,blocks and rings can be tested. Thus, the potential materialscombinations are endless. However, the interlaboratory testinghas been limited to metals. In addition, the test can be run withvarious lubricants, liquids, or gaseous atmospheres, as desired,to
5、simulate service conditions. Rotational speed and load canalso be varied to better correspond to service requirements.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly. Wear test results are reported as the volume loss in cub
6、icmillimetres for both the block and ring. Materials of higherwear resistance will have lower volume loss.1.4 This standard 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
7、practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 2714 Test Method for Calibration and Operation of theFalex Block-on-Ring Friction and Wear Testing MachineE 122 Practice for Calculating Sample Size to Estimate,Within a Toler
8、able Specified Error, The Average forCharacteristic of a Lot or ProcessE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG40 Terminology Relating to Wear and Erosion3. Terminology
9、3.1 Definition:3.1.1 weardamage to a solid surface, generally involvingprogressive loss of material, due to relative motion betweenthat surface and a contacting substance or substances.3.1.2 For additional definitions pertinent to this test method,see Terminology G40.4. Summary of Test Method4.1 A t
10、est block is loaded against a test ring that rotates at agiven speed for a given number of revolutions. Block scarvolume is calculated from the block scar width, and ring scarvolume is calculated from ring weight loss. The friction forcerequired to keep the block in place is continuously measureddur
11、ing the test with a load cell. These data, combined withnormal force data, are converted to coefficient of frictionvalues and reported.5. Significance and Use5.1 The significance of this test method in any overallmeasurement program directed toward a service applicationwill depend on the relative ma
12、tch of test conditions to theconditions of the service application.5.2 This test method seeks only to prescribe the general testprocedure and method of calculating and reporting data. Thechoice of test operating parameters is left to the user. A fixed1This test method is under the jurisdiction of AS
13、TM Committee G02 on Wearand Erosion and is the direct responsibility of Subcomittee G02.40 on Non-AbrasiveWear.Current edition approved May 1, 2005. Published May 2005. Originallyapproved in 1983. Last previous edition approved in 1998 as G 77 98.2For referenced ASTM standards, visit the ASTM websit
14、e, 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 Conshohocken, PA 19428-2959, United States
15、.amount of sliding distance must be used because wear isusually non-linear with distance in this test.6. Apparatus and Materials6.1 Test SchematicA schematic of one possible block-on-ring wear test geometry is shown in Fig. 1.36.2 Test RingA typical test ring is shown in Fig. 2. Thetest ring must ha
16、ve an outer diameter of 34.99 6 0.025 mm(1.377 6 0.001 in.) with an eccentricity between the inner andouter surface of no greater than 0.00125 mm (0.0005 in.). Forcouples where surface condition is not under study, it isrecommended that the outer diameter be a ground surface witha roughness of 0.152
17、 to 0.305 m (6 to 12 in.) rms or centerline average (CLA), in the direction of motion. However,alternate surface conditions may be evaluated in the test, asdesired. It should be kept in mind that surface condition canhave an effect on sliding wear results.6.3 Test BlockAtest block is shown in Fig. 3
18、. Block widthis 6.35 + 0.000, 0.025 mm (0.250 + 0.000, 0.001 in.). Forcouples where surface condition is not a parameter under study,a ground surface with the grinding marks running parallel tothe long axis of the block and a roughness of 0.102 to 0.203 m(4 to 8 in.) CLA in the direction of motion i
19、s recommended.However, other surface conditions may be evaluated as de-sired.6.4 Analytical Balance, capable of measuring to the nearest0.1 mg.6.5 Optical device (or equivalent), with metric or inch-pound unit calibration, is also necessary so that scar width canbe measured with a precision of 0.005
20、 mm (0.0002 in.) orequivalent.7. Reagents7.1 Methanol.8. Preparation and Calibration of Apparatus8.1 Run the calibration procedure that is in Test MethodD 2714 to ensure good mechanical operation of the testequipment.9. Procedure9.1 Clean the block and ring using a procedure that willremove any scal
21、e, oil film, or residue without damaging thesurface.9.1.1 For metals, the following procedure is recommended:clean the block and ring in a non-chlorine containing solvent,ultrasonically, if possible; a methanol rinse may be used toremove any traces of solvent residue. Allow the blocks andrings to dr
22、y completely. Handle the block and ring with clean,lint-free cotton gloves from this point on.9.2 Make surface texture and surface roughness measure-ments across the width of the block and the ring, as necessary.Note that a surface profile does not completely describe asurface topology. Scanning ele
23、ctron micrographs may be used,as desired, to augment the description of the wear surfaces.Clean the block and the ring if necessary as in 9.1.9.3 Demagnetize the metal specimens and ferrous assembly.Weigh the block and ring to the nearest 0.1 mg.9.4 Measure the block width and ring diameter to thene
24、arest 0.025 mm (0.001 in.).9.5 Clean the self-aligning block holder, ring shaft, andlubricant reservoir with solvent.9.6 Put the self-aligning block holder on the block.9.7 Place the block in position on the machine and, whileholding the block in position, place the ring on the shaft andlock the rin
25、g in place, using a test method in accordance withthe requirements of the specific machine design.9.8 Center the block on the ring while placing a lightmanual pressure on the lever arm to bring the block and ringinto contact. Be sure the edge of the block is parallel to theedge of the ring and that
26、the mating surfaces are perfectlyaligned. This is accomplished by making sure the specimenholder is free during mounting so that the self-aligning blockholder can properly seat itself. Release the pressure on thelever arm.9.9 One may choose either a preloading or a step-loadingprocedure. Generally,
27、preloading is chosen for variable speedmachines, while step-loading is chosen for fixed speed ma-chines in order to avoid an initial high wear transient. Thedifferences in the two procedures are indicated in 9.10-9.22.9.10 Place the required weights on the load bale and adjustthe lever arm in accord
28、ance with the requirements of thespecific machine design. Then remove the load by raising theweights, if using the preloading procedure, or by removing theweights if using the step-loading procedure.3Several machines have been found satisfactory for the purposes of this test.These models may differ
29、in lever arm ratio, load range, speed control (variable orfixed), speed range, and type of friction measuring device.FIG. 1 Test SchematicG7705e129.11 If running a lubricated test, clean all components thatwill come in contact with lubricant; fill the lubricant reservoirwith lubricant to 6.4 mm (0.2
30、5 in.) above the lower surface ofthe ring; rotate the ring several times.9.12 Set the revolution counter to zero.9.13 Gently lower the weights, applying the required load, ifusing the preloading procedure.9.14 If using a variable speed machine, turn on the machineand slowly increase the power to the
31、 drive motor until the ringstarts to rotate, recording the “static” friction force. Continue toincrease the rate of rotation to the desired rate. If using a fixedspeed machine, simply turn on the machine.9.15 If using step-loading, start the machine with noweights, then gently add a 133-N (30-lbf) l
32、oad every 200 revuntil the required test load is reached. Adjust the rate ofrotation as needed. If the required load is less than 133 N, applythe load in one step.9.16 During the test, record the friction force, lubricant orblock temperature, as required, and, if desired, the verticaldisplacement of
33、 the block.NOTEThe outer diameter and concentricity with the inner diameter are the only critical parameters. The inner diameter is optional depending onmachine design. The inside diameter taper shown fits a number of standard machines.FIG. 2 Test RingFIG. 3 Test BlockG7705e139.17 Stop the test manu
34、ally or automatically after thedesired number of revolutions.49.18 A final “static” friction force may be measured with avariable speed machine. Leaving on the full load, wait 3 min 610 s, then turn on the machine and slowly increase the powerto the drive motor until the ring starts to rotate, recor
35、ding the“static” final friction force. Then turn off the motor.9.19 Remove the block and ring, clean, and reweigh to thenearest 0.1 mg.9.20 Make surface roughness measurements and profilome-ter traces across the width of the block and the ring as desired.Atrace along the long axis of the block, thro
36、ugh the wear scar,is also useful to verify the scar depth and shape.59.21 Measure the scar width on the test block in the centerand ;1 mm (0.04 in.) away from each edge. These measure-ments shall be to the nearest 0.025 mm (0.001 in.). Record theaverage of the three readings. Sometimes oxidation deb
37、ris or alip of plastically deformed material will extend over the edgeof the wear scar (Fig. 4). When measuring scar width, try tovisually ignore this material or measure the scar width in anarea where this is not a problem.9.22 Tapered scars indicate improper block alignment dur-ing testing. If the
38、 three width measurements on a given scarhave a coefficient of variation of greater than 10 %, the testshall be declared invalid.10. Calculation10.1 Calculation of Block Scar Volume:10.1.1 Block scar volume may be derived from block scarwidth by using Table 1 (applicable only when ring diameter is34
39、.99 6 0.025 mm (1.377 6 0.001 in.) and scar length (blockwidth) is 6.35 + 0.000, 0.025 mm (0.250 + 0.000, 0.001in.).45400 and 10 800 revolutions have been used for metals in interlaboratory testprograms.5On some of the old test machines, it is possible for the block to move back andforth slightly, i
40、ncreasing the apparent size of the wear scar. If this problem issuspected, a profilometer trace through the wear scar will verify whether or not thescar shape corresponds to the curvature of the ring.A. A good rectangular scar with straight edges.B. The center of the scar is curved because the block
41、 was crowned. Also, debris covers the center left edge of the scar. Ordinarily, the debris should be visually ig-nored, but in this case scar curvature makes this too difficult. The test should be rerun.C. Severe galling resulted in jagged scar edges and a lip of plastically deformed material along
42、the right side of the scar. The raised lip of material is excluded fromthe scar measurement. The cross hair should be run to a visual average of the jagged edge, not to the point of a zigzag.D. Tapered scar with jagged edges. This scar is too tapered (coefficient of variation 10 %); therefore, the t
43、est should be rerun.FIG. 4 Block ScarsG7705e1410.1.2 The preferred method of calculating block scarvolume is by using the formula shown in Fig. 5. This formulamay be programmed on a calculator or computer.10.1.3 Block scar volume is not calculated generally fromblock mass loss because block mass is
44、subject to effects ofmaterials transfer, generation of oxide films, or penetration ofthe material by the lubricant. Keeping in mind the abovefactors, block mass loss may be interpreted semiquantitativelyin a comparative evaluation of various material couples. If theblock scar cannot be accurately me
45、asured following 9.21 andthe guidance in Fig. 4, a scar volume should not be calculated,but a notation made of the problem; for example, materialtransfer, plastic deformation, and so forth.10.2 Calculate coefficient of friction values from frictionforce values as follows:f 5 F/W (1)where:f = coeffic
46、ient of frictionF = measured friction force, N (lbf), andW = normal force, N (lbf).10.3 Calculate ring volume loss as follows:volume loss 5ring mass lossring density(2)NOTE 1If the ring gains mass during the test, the volume loss isreported as zero with a notation that weight gain occurred. Mass los
47、s iseffected by material transfer from one component to another, by genera-tion of oxide films, or by infiltration into porous material by the lubricant,or combinations thereof. If material transfer to the ring is obvious, then aring scar volume should not be calculated from the weight loss measure-
48、ment, but a notation should be made that material transfer occurred.11. Report11.1 Report any unusual event or an overload shutoff of themachine (on some machines it is possible to have an automaticshutoff at a preset frictional load). If the machine malfunctionsor a test block has a tapered scar, t
49、he data shall not be used, andthe test shall be rerun.11.2 Report the following:11.2.1 Test Parameters:11.2.1.1 Block material and hardness (whenever appli-cable),11.2.1.2 Ring material and hardness (whenever applicable),11.2.1.3 Ring and block initial and final surface roughness,11.2.1.4 Ring rpm,11.2.1.5 Lubricant,11.2.1.6 Test load,11.2.1.7 Test distance (see 14.1), and11.2.1.8 Number of duplicates run for each test condition.TABLE 1 Block Scar Widths and Volumes for Blocks 6.35-mm Wide Mated Against Rings 34.99 mm in DiameterBlock Scar Width(mm)Volume(mm3)Width(m
